I’m in sonic heaven with my new amp now!

Wait!

I don’t know about you but I’m certainly not like this. I know most folks would be satisfied with their tube amp after the first build but not me. I’m not like the 95% here. I’m an Alpha Diyer, I’m the top dog 5%.

But first of all, forgive me for I’m an uncouth fella. No, I don’t spout Byron, I don’t drink red wine or whatever the fancies that elitism hobbyists like audiophiles like to engage in. Instead, let me confess. I’m a pot bellied, hair receding, foul mouthed dude. Led Zep is my type of music and I love my brew of common man stout. In this regard, I’m the 95% Sir. Why heck, I even pick my nose in public. [*facepalm*]

An Alpha Diyer is always exploring ways to improve on his system. So much so that in the back of his mind, a trip to a hardware store, departmental store, IKEA etc is always an audio excursion.

And so, I’ll illustrate what an Alpha Diyer will do once he built his amp. And it’s certainly no lounging around.

But first of all, let me introduce you to the Expletive Factor. You know the reaction when the sound improved by so much that you JUMP (standing up doesn’t count) up from your seat and start spouting swear words, expletives… so bad that I can’t even write them here? (I still want this site to be family friendly, okay?)

What we are looking for is BIG XXXXing improvement in sonics. Not subtle changes that you have to A-B like hell, until your face looks like you are constipating to hear the difference. Imagine an improvement so great that you leap out off your listening chair and spew the most colourful language known to mankind!

Better still, if you swear words that aren’t in your daily vocabulary. That can only mean the sonic improvement is HUGE!

Okay, here’s what an Alpha Diyer will start off with.

Build the best power supply you have heard — Very High Expletive Factor
I mean it. The best power supply you have built, heard and optimized. Not because some dude (like me) said so. We all value different things in audio so it’s best to go back to your experience.

For me, I like choke input, lots of chokes, not too high capacitance and 100 Hz hum reduction via tuned choke.

I arrived at this supply after years of building tube amps. The 47uF caps are Solen metalized polypropylenes but the 20uFs are oil capacitors. Oh yes, the supply is HUGE, HEAVY and screams ALPHA all around. Notice there’s no electrolytics anywhere.

Move beyond simple self bias stage — Very High Expletive Factor
Initially I had a simple self bias stage at the cathode. However, you can’t move earth if you stop here. You got to experiment.

On another amp I built years ago, I used LED at the cathode and didn’t quite like the sound. The bass got too boomy. Looking back, it could be the speakers’ issue rather than the amp.

Anyway, for this mod, I’m using Cree Schottky diodes here, as illustrated by Maxamillion on Audio Asylum. 3 diodes gave me the cathode bias I need.

Optimize parafeed — High Expletive Factor
In my first build, I was using a 5k:8 parallel feed output transformer from Magnequest. The 4.7uF parafeed cap was optimized for bass response. A huge improvement over the initial 3.3uF.

As I was using 16 ohm speakers and I need a bit more gain from the tube, so I went for 3k:16 ohm trans also from Magnequest. Now the 4.7uF cap just doesn’t give me enough impact.

I don’t have any 6.8uF or larger caps. The next larger I have is a GE 17.5uF oiler so this went in and the bass impact came back after some running in.

Less Gain Stages — High Expletive Factor
Every gain stage somehow changes the signal. So if you could get by with less, do it! The 6E5P could actually put out 1-2W of power but as my DAC only outputs ~2V, the output power delivered to the speakers is now only ~0.3W.

By right, I should put in another gain stage to squeeze out more power from the 6E5P but since my speakers don’t need much power, I could get away with this. So what’s wrong with 0.3W?

Optimize signal/return path — High Expletive Factor
This makes hell lotta difference! If you ever worked on PCB layouts on high speed digital designs, the phrases “short signal path”, “return path”, “ground plane” etc all carry significant meaning to you. I’m not smart so I suffered and learned the hard way before I learned all this and I’m still learning.

Okay, that’s all I have done so far. In the spirit of this article, I’m not done yet! To be tried in the near future…

WE coupling

Try other spud tubes
Top of my head, 417, 5842, 6C45pi, 7788… Actually I have all these tubes in hand…

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Okay, here’s just a few things I have done over the past few weeks (or is it months) to improve the sonics of my system.

First thing first. Monica!
Even though I specified 220uF in the Mojo power supply for TDA1545, I had only 100uF when I tried her out. Thus with Black Gates Super E, total capacitance is 200uF. But the PCB was designed for 220uF Super E, so that’s 440uF capacitance in total.

So after finally ordering these caps, put them in and.. Wow! Lower noise floor! By my dummy ears, I’ll say around 2.7896dB quieter. Okay! I made that up! But it’s at least 2dB quieter as I have to crank an additional 3dB setting to hear hiss coming out of the speakers. Err, mind you, these are ~100dB speakers…

The above pic shows Mojo integrated with Monica3. You may notice there are a few additional modules there… Blame the 2 Pauls (Needs and Hynes!)

Paul Needs told me about these modules he got from Paul Hynes. According to him, major improvement to Monica’s sonics! Well, you know me, if anything could milk more honey out of my lady (err I mean ma dac), I’ll go for it!

So after I got the 5V and 0.83V regs from Paul Hynes, incorporated them into Monica + mojo. The 5V reg is actually a “super shunt” so it still needs a constant current source, and what better CCS than Paul Hynes’ CCS2? The 0.83V reg is fed off the 5V reg. So what we have is this :

With these mods, Monica + mojo improved a whole new level! If before, you have been stunned by this combo, now you’ll be peeing in your pants! Well, assuming you haven’t done so. Hee hee…

Both the 5V and 0.83V regs should be in stock couple weeks later.

Err, just realized the CCS2 has been obscured by the 0.83V reg in above pic…

Next comes Charlize!
First thing I did was change the power supply. Have been so happy using this Hitachi battery which out of all the batteries I tested, gave me the widest grin. I actually got a Paul Hynes PR3 earlier and did the power supply for Gabriel, but I never got to listen to it in my system as Gabriel liked it so much he wouldn’t let me take it back!

Couple months ago, bought this Stillpoints ERS fabric. The sales copy is very interesting. An average of 50dB attenuation from 10MHz to 17GHz! Wow!

Of course, I can’t test this figure but I could use my crummy ears and see if I could hear any difference. After all, whatever spec means moot if I can’t hear any sonic improvement.

Tried inserting strips in the center of the air core inductors, but couldn’t hear any difference. Wrapped around the inductors… Yes! Not surprising as the inductors are coiled such that the fields radiate outwards. Improvement isn’t as huge as all the previous tweaks on this page, but worth your time and effort! Certain instruments like cymbals gain “body” and “definition”, if it was a mash of splishy-splashy noise earlier.

And the tweak is so easy to apply! Definitely reversible. Just be careful not to come into contact with any solder joints or component leads as the ERS paper could be conductive.

But we are not done yet! Last but not least, installed 2 pieces of this wood diffusor behind my horns.

Few months ago, visited an audiophile friend about 300km away and had quite an epiphany listening to his system. You see, I kind of regard many of the audio “tweaks/accessories” as snake oil – at least those that I can’t understand. Usually will just attribute any sonic improvement as psychological rather than real improvement. So imagine our surprise to come across this audiophile who has almost ALL the tweaks one could think of.

And listening was a revelation! The host was kind enough to let us listen with and without some of the tweaks. After just few seconds of listening, I was shocked. Gabriel was shocked.

From now onwards, we only regard the hyper inflated price as snake oil, but not the sonic improvement!

For starters, I’ll start with something I could understand and believe. Yes, no snake oil here. Just a simple diffusor. Will progress and experiment with other stuffs later.

All in all, it has been a fun journey but you know with audio, this journey never ends!

The post What I’ve done over the past few months to improve my system… appeared first on diyparadise.

Okay, actually building this integrated amp is a piece of cake. But I took so longggggg…

Chassis
I was determined to make a nice amp as my previous attempts all have a “frankensteinian flair”. So I took extra trouble to get the chassis done up really nice. Got hold of a nice piece of 1mm aluminium chassis. 1mm sounds too thin right? But it’s holding up almost 20kg of iron pretty well right now. Anyway, took me 1 day to drill all the holes I need. 1 day to paint and… an eternity for it to dry!

I used hammertone paint here. Was told that “they’ll dry within an hour”. Really? Okay. Applied first coat (diluted with thinner of course) and left it under the sun to dry. An hour later, was happily applying second coat when I noticed the previous coat was “moving”! Dang! Needless to say, third coat was many hours later. Still not fully dried. Got fed up. Became desperate. Left chassis under the sun. Left it in the car parked under the sun… I thought this should be okay right? But as I grabbed the chassis, I left my fingerprints everywhere! Grrrrr!

Wiring
Seriously, watching paint dry has never been this interesting. Okay, enough talk about the chassis. Made me mad! Wiring is straight forward. Was determined to do it nicely this time as well, but my attention span only lasted a few solder joints. After that was sloppy, sloppy, sloppy job again… Now you know me. But when I rebuilt the power supply circuitry (to kill hum) I rebuilt the signal circuitry as well, using tagboards. Everything looks neater now, but this is relative.

Testing
Testing is easy. Just make sure all voltages are pretty close to that on schematics and you are fine. Sometimes you get a big difference and it could be either your incoming VAC or your heater voltage being out of whack. So check your incoming VAC and heater voltages as well.
Does the power supply circuitry look different? Does the 1.1uF cap bother you? Without the 1.1uF, the ripple on the power supply is about 40mV. With this cap, it went down to single digits. You can read more about it here.

First build
My first build gave me bleeding highs. My ears bled when I hear the highs. Even violins are horrible. What’s wrong? Guru YH suggested the phase splitting isn’t up to mark. Basic electronics tell you that you can improve the phase splitter performance quite easily… but that is another article…

Anyway, as I attempted to kill whatever hum that I was still having, I rebuilt the power supply AND rebuilt the signal circuitry. The layout looks cleaner now. Fired it up and… the highs are okay! Whatever I did wrong previously, I must have done it right this time.

Listening
Critical listening revealed several flaws. The sound is veiled, muddied. The highs are okay but the bass is quite rolled off. Also, you need to crank your volume pot quite high… Hmm…

Complicating the Simple EL84.

diyparadise.com

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Some Frequenty Asked Questions. (actually most of it I thought of myself)

How does it sound?

Oh the sound! It’s very transparent. Doesn’t have a strong character. For those looking for transparency in their system, this is highly recommended! However, if you are looking for a sweet sound, then I recommend the 5965 in a different configuration. Will post this on my Projects page later.

Why does it sound kind of “edgy” in my system?

A friend did describe my preamp as “edgy” too (though my tin ears can’t tell). Solder grid stopper resistor of 120-150 ohm on grid of both channels and it worked great!

I don’t like your power supply filter and would prefer 100H-100uF-100H-100uF.

Of course! This is a DIY project remember? So do it anyway you like. I opt for a low capacitance high inductance power supply filter circuit but you can do it anyway you like. You could build it as capacitor input power supply. No problemo.

I finished building it, and proceeded to power on without tubes…

Oh no! Don’t do that! Without tubes, the transformer is not being “loaded”. The voltage can get very high! If it gets higher than the voltage rating of your capacitor, your electrolytic cap might explode! Always power on with tubes installed.

I hooked it up to the rest of my system but it hums… can play music though.

Hum is good. It means you are almost there. (this doesn’t sound comforting heh?) Write to me and we’ll try to work out how to reduce hum.

I don’t like your choice of parts. I would prefer tantalum resistors, Black Gate capacitors, Jensen copper foil capacitors, silver wire, teflon socket…

Be sensible. Start off with something cheap and move on. The sound you get is a combination of the various “sounds” of all the parts you put in. Splurging on parts without knowing for sure how they will sound TOGETHER in a circuit is not very smart. Get it working first, then (if you wish) break your bank with all the audiophile parts in the world. Don’t be suprised if some of the expensive ones don’t suit your taste.

Your ground wire looks so puny. You are not macho at all.

Yikes! You are right. Definitely not macho at all. I was lazy. You could use a thicker gauge wire, or parallel a few strands to get a lower impedance ground.

Are you offering a kit?

I prefer to concentrate on just parts. Look, I have given the transformer winder info. (so no middle man charge here!) I have even given the wiring diagram, step-by-step. The rest is up to you. You can find someone in your area to do your chassis, to my (oops, your) liking. Time is scarce and for all my trouble asking someone to do the chassis etc, I will need to charge you. Definitely no more “value for money”.

I heard that running one tube for each channel sounds better than utilizing both triodes in one tube.

I haven’t tried this as the other tubes I have been familiar with are all run both channels in one glass but if you DIY it, you can do it any way you like. Do let me know how it sounds. If it really sounds better this way, everyone should know. On an unrelated note, thank God I’m not offering kits. Otherwise, can you imagine how much work I have to bear to have all chassis reworked?

I actually prefer integrated amps. Never like the idea of preamp-power amp.

Ditto here. But then everyone has his/her own opinion. And my way is no superior to your way, vice versa. If you use power hungry speakers, solid state power amps is a must without breaking the bank. Tube preamps offer the opportunity to get tube sound at a lower cost. Alternatively, use this preamp circuit as your CD player output stage!

How many 5687/6X4 do you expect to sell?

I’m not expecting to sell many. The whole idea of doing this is to show you that building tube amps (or preamps) is very simple. There’s nothing magical inside. There’s nothing to “tweak here and there otherwise it won’t work”. You know, that kind of nonsense some folks spew to fool you into thinking DIY tube amps is only for electrical engineers. Once you understand this and start your first DIY project, trust me, this is going to be your most rewarding journey.

Okay, will stop here. Let me know if you have more queries.

The post How to build your own tube preamp FAQ appeared first on diyparadise.

by Graham Woods and Denise Oh, Cottle Bridge, Australia

Read the follow up report here!

For serious listening, my partner Denise and I power our primary system from an inverter fed by a Trojan J185G 12 volt battery, so the obvious 12 volt source for our Monica 2 was the same battery.

Fitted with a 2200mF cap and fed by the Trojan, our Monica sounds beguiling (see my Love Letter of 20.04.2007). There’s a drop in sound quality when Monica is on the battery and the rest of the system is on the mains, but that’s not Monica’s fault: blame relatively crappy mains power (which, of course, is why we prefer the inverter).

Monica 2 on our battery sounds great and, given our set-up, a battery is the most convenient power source and costs us nothing extra, so we’d never considered an alternative. Until recently.

A few weeks ago I read Clive Walker’s Love Letter [15.1.2007]. Clive had tried a battery with his Monica 2, but had decided that his own PSU sounded better (for details see his L.L).

I knew Clive’s experience wasn’t unique; other reviewers have praised battery power for some of its qualities but have also had some reservations. The main short-comings of a battery, compared with a PSU (I’m referring here to any active PS), seem to be diminished bass and treble extension and (as a consequence?) some loss of body and slam and of ‘PRAT’. Clive added another: some loss of low-level detail. I haven’t seen this reported by anyone else and it might be the result of Clive’s choice of battery; more on that later.

Despite its reported shortcomings, it seems to be almost universally agreed that battery power – for Monica 2 and for at least most other NOS dacs – offers blacker silences between notes and more transparency and ‘air’. When you’ve heard these qualities it’s hard to give them up: in fact they’re the qualities that make our ‘inverter power’ superior to our mains.

So, should we use a PSU or continue to use a battery? Is the choice inevitably a trade-off? These were the questions that prompted Denise and me to do a comparison. Before I talk about what we found though, I want to mention the results of an earlier test.

Big Battery vs Bigger Battery
A few months ago Denise and I had experimented with a standard car battery (90 RC, 460 CCA) in place of the 140 AH Trojan (both fully charged). For powering a Monica 2 most people would call the car battery big; we certainly thought it would be big enough to match the Trojan, and in fact our main interest was in the difference that might come from having a power supply for Monica that was separate from the –battery – power supply that fed the rest of the system.

We pitted the car battery against the Trojan in two configurations: the Trojan powering just the Monica (the rest of the system on mains power); and the Trojan powering Monica PLUS the rest of the system. (We didn’t use the car battery to power Monica plus the rest of the system. Compared with the Trojan it’s small, and it’s not a deep-cycle battery: it’s definitely not designed for powering an inverter.)

We’d expected that a separate, though smaller, battery for Monica would at least hold its own against a larger battery that she had to share with an inverter, but we were wrong. The bigger battery produced indistinguishable results in each configuration and in each case it outperformed the smaller one. It wasn’t a case of night versus day but the differences were quite obvious. Compared with the Trojan the car battery offered about the same (certainly not more) bass and treble extension and the same ‘battery qualities’ of black silences, transparency and air; however there was slightly less low-level detail and the presentation definitely lacked the body and slam produced by the bigger battery – qualities often associated with a good LP.

Big Battery vs PSU
Our battery for this comparison was the one I’ve mentioned: a Trojan J185G, conservatively rated at 140AH for 5 hours. Our PSU was the unit whose regular job is to charge the Trojan. It’s a laboratory PSU from ‘Powertech’, a Jaycar house brand (although I’ve seen the identical unit in other electronics shops, just with THEIR badge on it): reasonably large and heavy; variable 3-15V; analogue volt and amp meters; ripple and noise < 10mV (RMS). It was fairly easy to re-jig this so that it was fed from the inverter and could thus be used as an active power source for Monica.

We agreed to feed the PSU to Monica with her 2200mF reservoir cap still in the circuit. I wasn’t keen to cut the cap out of the circuit for the sake of a short-term trial and in any case Denise and I didn’t think it would affect the PSU’s performance. Others might disagree however, or, regardless, might want to experiment.

We warmed the system thoroughly, on mains power; switched to the inverter; played a disc for about another 20 minutes; then began the audition. It’s hard to hide the switch-over from one source to another so at all times both Denise and I knew which source was which.

We listened first using the battery. Then we switched to the PSU, which was also taking its power from the inverter, not the mains. I made sure that the voltage from the PSU was the same as that currently being delivered by the battery, now under load from the rest of the entire system via the inverter. At intervals of a few minutes I switched back to the battery, then back to the PSU, then once more back to the battery. Denise and I took notes independently; the same tracks of a single CD comprised all listening samples.

Our Conclusions
In most respects our conclusions were very similar. The PSU sounds nice, perhaps you could say ‘slightly warm’, but compared with the battery it’s muddy, and yet, in Denise’s opinion, actually produces a ‘thinner’ sound. What I think she’s getting at is that it actually has less body and slam than the battery, but with the muddiness masquerading as ‘body’.

I didn’t notice the thinness that Denise reported. What I did notice was what a lot of commentators have already remarked on: the battery produced dramatically blacker spaces between the musical notes. The result is significantly more transparency and air, a spaciousness and lightness that the PSU just couldn’t match. Along with that, though, the battery produced at least as much treble and bass extension, a larger sound stage and more detail, and more slam and emotional involvement. In these areas Denise’s conclusions were the same as mine. Putting it all together, there was no parameter on which the PSU was superior.

Having Your Cake and Eating it too
Our experiments suggest that you CAN have the best of both worlds: i.e. the virtues of both a PSU and a battery. However, you can’t get them all unless you use a fairly big battery. Even a standard car battery isn’t really enough, although it does seem to deliver most of the goodies of its larger cousins. I’m reasonably sure, now, that as the size of the battery goes down, more and more of the virtues of battery power are lost; if you plan to use nicads, or lithium cells (as Clive did), or even a small SLA, you’ll definitely be in the compromise zone, where the merits and demerits of the two power sources will need to be carefully weighed up.

Passing the Baton (Passing the Buck?)
Our experiments comprise not much more than a couple of case-studies, so it would be premature to assume that our results are universally valid. I’d like to see the results of more experiments, using different amplification, different sized reservoir caps (and perhaps different brands), various types and qualities of PSU, perhaps a battery even larger than the one we use. On this last point: Denise and I are considering a 500AH 12 V battery bank. If we go ahead with that we’ll definitely want to see whether even 140AH is too small a battery to get the most out of Monica 2.

The post Batts vs PSU appeared first on diyparadise.

by Graham Woods and Denise Oh, Cottle Bridge, Australia

A few months ago I reported on the results of some comparisons Denise and I had made between batteries of different sizes and between a large battery and a good quality PSU (see ‘Batteries and PSUs’). I mentioned then that we were considering buying a 500AH battery bank. We recently did, and we were keen to see how the new battery bank performed against our existing Trojan J185G. The fairly hefty Trojan had outperformed a standard car battery and we expected that an even heftier battery bank would either outperform the Trojan or produce no audible difference. However, read on!

The Trojan J185G is a deep cycle 12V battery rated at 140AH for 5 hours. Our new battery bank comprises six Century Yuasa VCI8C 2V cells linked by lengths of 30mm X 6.5mm thick copper bus bar. The cells are clustered (2 X 3) so as to keep the buses as short as possible. These cells are rated at around 600AH (5 hours).

We began our tests by running everything from the new battery bank: i.e. an inverter to provide 240V for our Rega Planet 2000, a VTL Super Deluxe preamp and a VTL 90/90 power amp; and a direct feed from the battery bank to our Monica. Our ‘test disk’ was our usual: Simon and Garfunkel’s ‘Old Friends: Live On Stage (2005)’. The presentation had the same slam as usual, but compared with our memory of how the system had sounded only two nights before – on the Trojan – it sounded hard and aggressive, though clean and detailed.

We get variations in sound quality that seem to depend on the weather, and at first we attributed the degradation in sound quality to that. However the same sound signature was apparent the next night, and two nights after that; this couldn’t be just the weather!

On the fourth listening evening we bit the bullet. During the day (a Sunday) I’d connected our Monica to the Trojan, leaving the rest of the system to be powered by the new battery bank – from now on I’ll call it ‘the Century’. Denise deliberately didn’t know whether Monica was connected to the Trojan or the Century, though she did know that the 240V supply would come from the new arrival.

We played the first two tracks of our test CD; then I switched Monica to the Century and we played the tracks again. Finally I switched Monica back to the Trojan and we listened to the same tracks. As usual we made separate notes and didn’t discuss our impressions during the auditions.

Before these tests I was hoping to hear, at worst, no difference between the two power sources. I certainly didn’t want the Trojan to outperform the new battery bank: the whole idea was to obtain a longer-lasting power supply and, as a bonus, to sell the Trojan to offset some of the cost of the changeover. Just before we began this phase of our tests Denise confided that she, too, was hoping to hear no difference.

However there was no way we could avoid the facts. Though our words were sometimes different, our opinion was the same. Fed by the Trojan our Monica returned to what we were used to; the hardness, the clinical ‘dryness’, the ‘CD’ edge of the music disappeared.

For the sake of completeness Denise and I then compared the Trojan with the Century as a source for our inverter-generated 240V supply, with Monica taking her power consistently from the Trojan. Here the differences were more subtle, and there was no clear winner. The Trojan offered a more mellow sound, with a slightly rolled off top end; the Century offered a sound that was more detailed and had a little more air and transparency, and which, probably as a result of that, conveyed the ambience of the performance a little more convincingly. Denise and I agreed that the Trojan would be kinder to hard, ‘edgy’ CDs, whereas the Century would be the winner with top quality sources. On balance, on the night of our tests, I preferred the Century; for Denise it was a dead heat. The bottom line, however, is that, even going through an inverter, these batteries didn’t produce the same sound.

Putting it all together, I believe we have to revise our earlier conclusion (in ‘Batteries and PSUs’). When it comes to powering Monica 2, it’s possible that the SIZE of the battery is not very important at all; it could well be that it’s the BRAND of battery that’s most important. Although we haven’t put them head-to-head, our recollection of the sound of the car battery (not a Century Yuasa and not a Trojan) is that, as a power source for Monica, it was actually superior to the sound produced by the 600AH Century, despite being only about half the size of the Trojan and an eighth the size of the newcomer.

There’s probably only one way to decide the issue: to do a series of tests using batteries of, say, three different sizes and, say, five different brands. That could be expensive, and would certainly be time-consuming (and it won’t be us who’ll be doing it!). In the meantime, however, Denise and I would put brand ahead of size, and, when our Trojan finally dies, we’ll be buying a – smaller – TROJAN replacement to power our Monica.

[yeo’s comments : yes, battery makes to me is more important than capacity. i have been very happy with a yokohama rechargeable sealed lead acid until i tried a hitachi one day at an insistence of a customer. oh my! never going back to the yokohama now. call it their secret sauce if you which but the chemical composition of the battery definitely affects its performance.]

FURTHER THOUGHTS
It might be speculated that the new battery bank needs to be run in: after all, its six cells are linked by copper buses that might be likened to interconnect cables, and these, at least, might need to be broken in. I doubt that this is an important factor though, because the Trojan also outperformed a well run-in standard car battery (see ‘Batteries and PSUs’). Nevertheless, Denise and I will do some more tests after the Century has racked up a couple of hundred hours. Long before that we’ll clean all contacts between cells and apply a contact enhancer, to see if that makes a difference.

Perhaps the copper buses that link the cells are acting like small antennae for RFI or other grunge, but, having done extensive tests in this respect on other aspects of our system, I believe that can be ruled out.

Is the superior performance of the Trojan with Monica the result of its being a SEPARATE power supply for her? I would say no: in our earlier comparison of the Trojan and a car battery the Trojan outperformed the smaller battery even though it (the Trojan) was also powering the rest of the system.

CONCLUSION
Before our tests I would have smirked if someone had suggested that the SORT of 12V battery you use could make a difference to how Monica sounds. I recall now that Yeo has reported just this possibility, as a result of the experience of a few DIYers, and I remember that I was sceptical when I read that. After all, the battery just supplies 12V DC, ultimately to be massaged by Monica’s circuitry anyway, and above a possible minimum why should even size make a difference, let alone brand? I’m not willing to speculate as to why, but our tests suggest that brand certainly DOES make a difference. Our most recent tests and the earlier ones, taken together, also suggest that size related differences – if they exist at all – might be so subtle that they can be disregarded.

In addition to brand, perhaps battery TYPE makes a difference: nicad (or nickel hydride or lithium) versus lead acid; or even SLA versus the more traditional flooded lead acid battery. It’s quite possible that a certain sort of active PSU, in a particular system, will sound better than ANY battery. And does a particular battery type, or brand, sound equally good in all systems? Possibly not. A rich playing field awaits the dedicated experimenter and tweaker …

The post Monica2 and Batteries appeared first on diyparadise.

Experiments with powering Charlize (and then Charlize2) showed what a big sonic improvement different power supplies could bring.

Thus, I was trying the same with Monica3. Tried various switching power supplies, built a linear supply, built/evaluated/listened-till-ears-bled up to 3 types of regulators but I’m still unhappy.

Sure, Monica3 never fails to bring a smile to my face but I want More! More! And More!

Just when I thought I should build more regulators and listen and evaluate some more (and in the process lose my sanity as well), a DIY friend showed me this link. MT Audio Design’s MF-2001".

Now from time to time, I’m always exposed to some really interesting ideas, thanks to the wonderful World Wide Web, but never had the luxury of time to build/execute/listen to these wonderful ideas. But since I’m working on Monica3’s power supply, I thought why not give it a try. After all, the idea is so simple yet makes so much sense!

Thus I got the trans wound. Note that this is a double bobbin design. More on this later.

And built a linear 24VDC supply for Monica3. I’m aware that the caps on Monica3 is only rated for 25VDC but my own Monica3 I have let her run at 25VDC for more than 6 months now and she’s still singing happily. The LM317 chip deserves a bigger heatsink though.

Now, this time, did I jive? More than that!

I was totally taken aback by how good this thing is! Flabbergasted! Smoking Catfish, this thing smokes!

Not only it expectedly cleaned up noise in the background, now I could play much louder than before and the system does not struggle with complex music any more. For example, when listening to choirs, with many voices singing simultaneously, it used to be hard to follow every individual voice, but not now! I even dared demo Carmina Burana’s "O Fortuna"!

This is so powerful I could even "see" into the details. When listening to one choir, I found myself saying,
"Hey you, kid in third row, fifth from left. I could hear you skipping two syllables. And when you sing, stand still! Quit swaying around!"

Ok, ok. This is what I built. Note that I didn’t even install any EMI/RFI filter at the input. There’s no regulation for 24VDC so I’m relying on the onboard regulators to work its magic. Both trans are specified as 30VA.

The key here is the first transfomer, the isolation transformer with a center-tapped secondary. I asked for 3 magic spells from the trans winder genie and this is what she gave me.

First, the trans took up any DC current prevalent in the mains supply, thus shielding it from the second trans.

Then with its lousy bandwidth (EI cores using "normal" grade iron), it is a noise filter. The fact that it is a double bobbin helps out even more. You see, usually the secondary windings are wound on top of the primary winding in a trans, usually separated by paper, but you can’t discount the possibility of mains stray noise coupling to the secondary.

With a double bobbin design, the primary is wound on one section of the bobbin, while the secondary is wound on another. Noise coupling between the two is greatly minimized. See how good an idea this is? I went the whole nine yards and had both trans wound double bobbin.

Thirdly, and this is the most important feature here. Common mode noise is filtered away due to the center tapped secondary. Now noise is, to some extent, easily filtered via capacitors and inductors etc but common mode noise is tough to beat as it’s "common", meaning it’s "everywhere". It’s prevalent at both legs of the transformer secondaries you see. Thus with the center tapped there, they both see a low impedance path to IEC Earth and thus "filters away".

Have I lost you yet? I hope not!

Anyway, this idea isn’t new. A search on Google shows many variations of this scheme with fancy names like "Balanced Power Supply" etc. As you can see, it’s nothing more fancy than just an isolation trans with a center tapped secondary. Well, add some EMI/RFI filters if you like.

What? Can’t find such trans? Well, the below version uses off-the-shelf transformers wired back-to-back. You could use 9-0-9 or even 12-0-12 as long as both trans’ are the SAME. The principle is just as sound but may work better due to even more levels of filtering. The optional capacitor provides an even lower impedance path for noise. Read this somewhere ago.

There you have it! Some simple and yet so effective. If you are macho, you should build one each for every gear in your system. One for CDP, one for DAC, one for preamp… Need to size the VA accordingly.

Feel free to build one yourself but if you can’t, let us build for you!

We even thought of a good name for this product. In line with our penchant for naming minor products after rock bands, you can’t go wrong with AC/DC!

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Match Made in Heaven: Batteries and Non-OS DACs

2 things make my knees wobble these days. Monica Bellucci and Battery Powered DACs.

“Hi yeo, Can I come over your place to listen to your battery powered DAC…”

Battery Powered DACs… Ahh…. Like Monica, How can anyone resist?

It makes lots of sense to battery power your DAC. Think of your signal chain. First you get digital ones-zeroes-ones-zeroes from reading the CD, then this digital information is fed to various processing IC till it finally reaches your Digital Analog Converter IC. It is from here that you finally get your analog signal, which is then fed to the preamp, power amp and so on.

Now, if you think about it, analog signal first appears at the output of the DAC, and it is low level, usually in milivolt range. At this level (1 milivolt is 0.001V), your analog signal is most susceptible to pollution – power supply noise. And this is where our old friend, the plain vanilla battery comes in. Of course, parallely speaking, battery powered phono preamps should be good too, right? ; )

Batteries, by virtue of it already being a constant DC voltage, should be a perfect power source right? Err, not quite actually. Read on.

Here’s the schematic. TDA1545 (and TDA1545A) accepts only EIAJ input format (I learned this the hard way), and not I2S so CS8412 needs to be configured to output EIAJ. CS8412 datasheet says it needs to be configured for Mode 5, thus only M2 and M0 are tied to 5V. The string of diodes is to give 2/3*Vcc reference to L/R output and Reference pin. Idea given by Thorsten Loesch on diyaudio.com/forums. You could use 3 pcs of AA cells as well, if you wish.

As you can see, I got lazy in the power supply department, and forgo the usage of shunt regulators like TL431. Hey, at least I used an inductor okay? Please note that M2 and M0 are tied to VD+ and not VA+.

Err, I just remembered I didn’t mention anything about the sonics of battery power. Well, apart from the OBVIOUS lower noise floor, music flows easier, more relaxed, more natural. One of the biggest benefits of battery power is a smoooooooth mids+highs, so distinct that whenever you listen to conventional AC-DC powered DACs, you’ll have “HARSH HIGHS” written all over the place (your friends’ place). But you could easily screw up! One of the DACs I built, I forgot to wire in a capacitor before the regulators. If you look at the schematic, that’s the capacitor just closest to the battery. Without this battery, I get a slight veil, particularly noticeable in the midrange. With this cap in, the veil is gone! But why oh why? Aren’t batteries perfect DC voltage sources?

Apparently, at static conditions, batteries are perfect but music is ANYTHING but static! Under dynamic conditions, probably chemical reaction inside the battery isn’t fast enough to cope. This plot here, by DIYer ALW, is very interesting.

Oh well, I guess battery + caps + regulator will have better noise plot?

Ok! Ok! The sound! TDA1543 should be familiar to you, unless you haven’t built anything yet. (Shame! Shame!)
Aside from the common “darkness” associated with non-os DAC, here’s a (very) brief summary of general impressions. All these with batteries of course.
Single TDA1543 – Good midrange. Good highs but lumpy bass.
8x TDA1543 – Midrange loses out to Single 1543. Midrange has less prescence. But highs and bass better than single 1543.
1x TDA1545 – Best Midrange here. Best overall sonic. Makes you scream “Mama Mia”! And this is the DAC I’m going to share with Monica Bellucci.

Arrivederci!

PS: If you have two left thumbs, but still want to have a taste of… “mama mia”, contact me.

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Non-Oversampling DAC saga continues with…

8x TDA1543

First of all, my apologies for so few updates on this website. I’ve been up to my neck with my day job, and spending most of my time living out of a suitcase. I don’t have to tell you this isn’t my idea of fun at all, or do I!? That said, in the short time that I had access to some solder fumes, I’ve revisited the non-os dac as I feel it’s the current weak link in the system.

What do you do if you think your DAC is the weakest link? Build another DAC? Play around with the circuitry? Add a tube output stage? Or breakdown and plough big money for some commercial design? Fortunately or unfortunately, yours truly is also a cheapskate so the last option will always be the LAST option.

Of particular interest to me is choice number one and the TDA1541 naturally calls for attention. Also, I just heard a good implementation using the PCM63. A wonderful chip too! But the added complexity, power supply requirement and additional gain stage… make this more than a weekend affair. Yes, more stuffs to play but with so little time before I hit the road again, I’m better off with something easier…

Carsten from Germany pointed me to Doede Douma’s excellent website, where he described in good detail his 8xTDA1543 non-os dac. Now Mr Douma even claims that this DAC sounds like SACD! Wait a minute, 8 pieces of dirt cheap DAC chips (hey! it rhymes) sound like SACD?! Woo hoo! This I got to try!

The circuit is so simple you can whip up in half an hour but as with all DIY projects, it’s a good idea to factor in 3x that amount, for time wasted looking for parts, soldering/desoldring a wrong orientated part, shit-happenings, Murphy’s Law… get the idea? And sorry, I’m not going to draw the schematic. It’s so simple it’s better to describe in words.

3 I2S input lines for pins 1/2/3.

Power supply connections across pins 4/5. Pin 4 is ground.

Left output through pin 6, with 249 ohm resistor to ground.

A pot to pin 7.

Right output through pin 8, with 249 ohm resistor to ground.

Mr Douma suggests a 2kohm pot for pin 7 but I can’t find this at home so I salvaged a 10kohm pot and paralleled a 1kohm resistor. In the end, settled for about 150ohm on this pin. For I/V conversion, Mr Douma suggests 270ohm but I could only find 249ohm, so just use it. And that’s all to it!

Tower of music! The I/V resistors are all mounted underneath for shorter signal path. The power supply comes in through those ferrite beads. Those components on the right were a failed attempt with the TDA1545 DAC. Will revisit this some day… Those on the left is the single chip TDA1543 DAC.

 

 

Though I took Mr Douma’s advice to leave some air gap in between DAC chips, I didn’t use a heatsink. Waily has built this DAC too and stressed the importance of keeping this DAC cool but I wanted to live on the edge! (Actually I’m lazy.) In this arrangement, I could only play for half an hour before the DAC starts to distort. Will HAVE to incorporate some form of cooling.

 

Okay, how does it sound? Way way better than the single chip version! I remember trying 4xTDA1543 a longgggg time ago and it didn’t appeal to me, so much so that I simply prefered the single chip but this time, with so many changes to my system, 8x smokes! Forget about “one chip to rule them all”, eight is the magic number here. And the strangest thing to me is that both Waily and I don’t notice any lackings in the highs at all. This despite the sin(x)/x mumbo jumbo and abscence of the parallel resonant filter circuit so crucial for the single chip version. Huh? Maybe we need to dig out those dastard ear wax… Never mind.

 

 

But improvement in sonics is a big leap. It simply sounds more fuller and more bodied. It images better too. Now Waily has found that choice of DC blocking cap to be very very critical to the final sound. We both like the Cerafines for a more natural/musical presentation but Waily has found the non-polarized Black Gates to be even better. I guess you know what I’ll do one day… Here, read Waily’s mail to me. His enthusiasm is infectious!

> Hi Yeo,

>

> Just some updates from me:-)…

> Tried out the dddac 1543, 8 pcs tda1543 piggyback cct.

> Switched on power and fine tune the Vref to 3.85V

> according to the site. Then MUSIC…

> Headroom:- Plenty of gain and it solves my needs of

> another gain stage:-).

> Smoothness,naturality:- Lost to single chip version,

> but it’s dynamic and bit hi-fi sound:-(

> Distortion:-Wow, everything improves, the slight

> roughness of single dac gone completly, clarity and

> definition is another level that single dac can’t

> attain.

> High frequency handling: This dac wins hands down and

> all those highs is MAGIC! guess what he mentioned that

> it is close to SACD is not unfounded, nevertheless I

> haven’t really got the real chance to listen to SACD

> setup so I can’t really compare, but the high is damn

> good!

> Low frequency handling:- It wins again and the bass is

> much tighter and register better.

> Mids:- Lose out to single dac as the voice is a bit

> thinner and not as sultry as before.

> Soundstaging and seperation:- It wins again against

> the single dac, now every instrument can be heard

> individually much cleaner and won’t muddied up when

> singer voice is in even in complex passage.

> Soundstaging is wonderful, I am totally immersed in

> the music and much improves over the single dac.

>

> Summarised, it is a bit HI-FI sound but it clearly has

> more advantage over the single dac, except is does not

> feel very natural and smooth over the predessor.

>

> The dac’s last only for 10 mins as overheating

> occurs:-(!!!, Found out that my regulator

> overheats(7808), quickly whip out DIY large heat sink

> over the regulator and problem is solved..(have to

> takecare the extra current of the 8 pcs tda1543). Also

> tried out the stacked dacs without cooling, no problem

> except realised that the Vref will drift once the

> temperature increase. Whipped out another tower with

> some stupid looking antenna like heat sink over the

> dacs, and it works better as the Vref will not drift

> much..Again these dacs really can cook HOT!!!

>

> After enough listening, still found that it lacks the

> smoothness, intimacy sound of single dac…!@#@#%#*

> looks like I have to do something, agak agak my

> coupling cap, the BG PK has something to do with it(no

> doubt I prefer BG in single dac, I guess a new

> matching caps has to be in in order to match

> perfectly).

>

> And in the cerafines, $#@*&!! ha ha now this dac is

> shinning!!At last, the smoothness is back plus all the

> plus point of the 8 dacs..Now it sounds not Hi-Fi

> anymore and I really have to let the single dac to

> go:-( as this dacs is way much better(IMHO and YMMV).

> It is very relax to listen to and it brings the music

> to another level that I may put a full stop to this

> dac selection/mods:-)

>

> No doubt the single dac is good! but this 8 dacs can

> proves it’s authority and improvement over it.Guess

> what will happens with 16/32 dacs:-)..

>

> Going to try using SLA battery to drives the dac once

> I got it…Must really see why people keeps using

> battery as power supplies over the normal heavy

> regulated supply..

>

> Pics is attached..

> Yeo, try it and see how this dacs goes in your system,

> hopefully u will like it too..:-)..

>

> Regards,

> waily.

 

Waily’s DAC.

As you can see, all the credit goes to Mr. Douma and Waily for their excellent work! I’m just a “reporter” here. : )

Now Waily has moved on. He’s now using batteries to power his DAC and absolutely love it! One day, one day…

 

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It’s a Mod Mod Mod Mod World

Hello folks. This time, your fearless diehard tube fan has been approached by a customer friend to “salvage” a horrendous sounding amp, of which the commercial make will be left unknown to you, in order to avoid blushes and embarassment (and flames and a lawsuit and many unhappy faces..). The challenge is simple: do what it takes to get good sound.

Interesting challenge? Lesser souls would have wilthered under the pressure and expectation of “good sound”. But not your fearless intrepid “solder slinger” from the Not So Wild Boleh Land of Malaysia. How to go about this? We could go about “upgrading” components to boutique parts but I need to keep an eye on the cost side (customer request). Furthermore, how much mileage can you get from a leaky car? Let’s check out the design first.

Taking a peek
At first look, the circuit is terribly complicated. 3 stages! A SRPP-ed 12AX7 followed by 6922 gain stage, then only the 5881 output tube. Of course, you could imagine the 12AX7 gain of 100x and 6922 gain of 30+ makes for some terrifying gain ! All this gain and we only need a gain of 20x to drive the 5881 to full power? Doesn’t make sense right? And then of course, snobbish folks at diyparadise look down on pretenders like 12AX7 and 6922! Sheesh!

Making sense in a senseless world
Now all this gain is necessary as the amp uses some judicious amount of negative feedback to correct its errors. As we know “negative” feedback means reducing gain, thus we need more gain. More feedback, more gain. More gain, more feedback. But all this gain is, in the end, burned off in the feedback circuitry. But why use feedback? Well, to correct for errors/distortion generated by the driver stages. All this is well but I believe we are starting off on the wrong foot! I believe in what is fundamentally right. Start off right and you have a higher chance of success. Start of wrong and you need to do lots of work to get it right. So why start off wrong?

If you think I’m bullshitting “all that gain” stuff, well, try disconnecting the feedback circuitry. With gain in the thousands, this thing is more alive than you think! It’s humming very loudly as every little noise/ripple on your power supply is amplified thousand times! It’s also damn microphonic. Just touching the chassis and you can hear it! Didn’t I tell you it’s alive? Damn cranky as well. Touch the chassis and it goes “bo-ee-iingggggg”. I don’t want to insult your intelligence but what do you think the chances of feedback reducing ALL this power supply dirt, microphony noise down to the minimum? Very good? Think again. How often does stuffs that work so well in theory work well in reality?

So out goes the feedback circuitry!
Now we don’t need so many gain stages anymore. I’ll say out with the 6922 stage. Bypassed all of it and now we have a SRPP 12AX7 driving 5881. How’s the sound? Nah. Still not up to my usual “high” (don’t laugh!) standards. OK. Took out the 12AX7 and put in my favourite 5965. Ah! Much better! More life, more immediacy. But highs are terribly rolled off. Wait a minute. BIG resistors as grid stoppers? I always feel that grid stopper should be inserted AFTER listening rather than BEFORE, but who gives a shit to what I think? Took them out and the highs are back! Soundstage, imaging all improved! Grrrr!

But still there’s a veil. Checked the circuitry. No, no, no. It’s running too low a current. I have had quite an experience playing with 5965 and to me, it sounds better with a bit more current. Say 5mA. Changed the cathode resistors and… It does sound better! But there’s still a veil. It’s warm and sweet but ultimate clarity is still not there. Hmm… I have played with 5965 before so I’m pretty sure it could do better. Could the Solen coupling cap be the culprit? Replaced it with Auricap and even non-audiophile friends could hear the difference! Yeah! But but but. Still the veil is there. I’m getting cranky now. Very very cranky.

Talking ’bout a revolution
I think I want to forego the SRPP 5965 and go for something totally different. Got to do something drastic. This just isn’t the way. I know 5965 sounds better so could it be the SRPP is not letting it “sing” Or is that the 5881 is not a nice tube? Consulted my customer friend and his words… “change the driver tube if you want to”. Cool! That’s the word I need! Why not use a medium mu linear tube like our favourite 5687? Since the B+ is 500V, we could use a sized up plate load resistor for even better loading on it. Note that the Simple 5687 uses only 10kohm. This, at 5x the plate resistance of the 5687, is already considered very good. But we are going to go macho here with 20kohm! That’s 10x plate resistance!

Wired in 5687 and attendant circuitry. It’s a breeze actually as it involves taking out more components than putting them in. Took this opportunity to install better parts as well. Using Welwyn wirewound for plate load (yes they are inductive but what is the problem when our resistor is 20kohm?), metal film for cathode and Elna Cerafine for cathode bypass.

Played music… jaw dropped, tongue rolled out, mouth agape, speechless, motionless, listening like an idiot, staring into the distance. I’m stunned. Everyone is stunned. Makes me think. WHAT THE HECK DO I EVEN WANT TO LOOK AT 12A*7 SHIT ANYMORE? WHEN MUCH MUCH SUPERIOR 5687s ARE READILY AVAILABLE?

Here’s ~10W of SE Class A power. Cheap to build too. Who needs 300Bs?

Right now, the amp is dead quiet. No hum, no microphony problems anymore. Leave these problems to 12AX7 fans. : ) With further mods changing from self bias to fixed bias, we could make provisions to cater for other octal based power tubes like EL34, KT88, 6L6 etc.

Life is good when you have many choices.

diyparadise.com

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