Well, its about a year later, thought I would post an update on this amp. It now has Russian 6P6S (6V6) output tubes. They are really nice, the bass and detail are very good. The extra (lower) bass from these tubes was a shock, but a good one  The Chinese OPT's were refitted. I measured them as 8 ohm to 6600 ohm but run them with 4 ohm speakers, so the primary Z is 3300 ohms. This does not seem to be a problem and sounds great. The circuit was modified slightly to run on 240V mains power instead of the stepped-down 220V. One LED array failed after fitting the 6P6S so it got converted to fixed bias. So how does it sound now, compared to my other 2 amps with Hashimoto OPT's, one with EL84 and the other with 6V6? Well its not quite as detailed, the sound is not as much 3-D, but, it's very sweet and enjoyable, and not so fussy on source quality, which the other 2 amps are. It gets used the most, but I rotate the amps sometimes and its always a pleasure to hear the music slightly differently through the other amps. My missus votes the Meng #1. For those looking for an EL84 PP amp with no sand, the Simple PP from tubelab.com would have to be the winner there (that is one of my other amps). The PCB layout is well designed, really quiet, and great stereo seperation. Anyway, cheers, catch you all later.

Ooops, a pic, hope you like it... here

That is interesting    I have never cared one hoot about which channel is left or right. My left ear and right ear never complained to me which channel they get to hear either  What happens when one is facing away from the speakers, the channels get crossed over again...oh well. Am I the only one who doesn't care? The only downside is if one speaker stopped making music, I would have no idea which amp channel had failed 

Looks fantastic Yeo, good price too. Just excellent. Black Crow should be a winner too.

You are so lucky living nearby. Give them a reasonably gentle break-in 20 or 30 hours, they don't sound very good for the first few hours. After 100 hours they are nearly there. Keep cone excursion below 3 to 4mm each way (i.e. 6 to 8mm total). There is also a paper cone version which I have heard in same boxes and they sound good too, hard to pick the difference, except the paper cone ones I heard were barely broken in. I don't think you will be disappointed.

I love them, the CHR70. I built the planet 10 Lotus speakers, great with 6W to 15W per channel. Can't say enough good things, but I never had good speakers before. Any change to the amp is easily detectable, they have good detail.

Sounds great Yeo, thanks!

> so what's your beef with silver plating? i'm all ears.

I find the easiest PCB's to solder have the HASL (lead) finish on the pads. Silver and gold basically need to be tinned and sucked dry first to ensure an easy solder job, in my experience. I know you like lead-free soldering, but the medical and aviation fields refuse to use it on reliability grounds. Lead-free is only used for consumer devices as far as I know. I dislike it (lead-free) in our hobby simply because I believe we are so small in contaminating the environment, compared to large corporations destroying the environment to make themselves some big money. Somehow, the politicians want the peasants to feel responsible for all the environmental damage, while the big companies strangle our resources for corporate profit. I am almost 50 years old, I can see through all the smoke screens now. When I was young, I used to wonder why my parents were so cynical....

Hi Yeo,

The 18VL reg is missing a track. I don't understand the pin-out of the various regs, the CCS makes sense but then the CCS output feeds the centre pin of the 5V reg, a bit confusing without knowing each reg's pinout. It looks like they are all the same, input/output/gnd for pins 1/2/3, or other way around?

I can look at checking the rest including the Paul N mod but need a fresh brain and that won't happen for another 3 days, my day job uses up most of my brain cells during the week...

Do you think there is enough room to squeeze in the 4th mounting hole?

Is it worth increasing the PCB size by say 10% to make it easier to build? And 10% bigger pads to make future mods easier?

Any chance of not being silver plated? Me and that silver plating do not get along very well

All looks good.

Ian.

Your posts are always a great read Jonas, good to hear from you again!

More food for thought....great article the sweet spot...

Ian

Hi Yeo,

You are the creator of the Simple EL84, have you forgotten its a Class A amp?

I think you have been working on a secret 20W EL84 and not telling us about it?

Am I right?

Ian.

I may be wrong but it looks like you have pin1 and pin2 reversed on the new connector.

Ian.

Excellent!

Anything is worth a try. Impedance matching is the big deal in my humble and limited experience. I am using the Mojo, then Lightspeed clone volume control, then Hypnotize to drive long audio lines to the amp.

Good luck fumbles, I haven't got round to it yet, been playing with other stuff, this time its a hybrid tube amp and a guitar amp for the young niece.

Ian.

Hi fumbles,

Its a bit of a brain teaser trying to work it out. I did the mod with BC type transistors, but I have the ZTX trannies now and need to fit them instead. When I do it, I'll draw a diagram or take pics or both. Don't hold your breath waiting, I've been pretty busy lately. The audioslave regulator is a big improvement too, its fairly easy to wire in. There are some pics on page 3 of this thread of doing the transistors that may help. I haven't added the extra diode or changed the resistor either, yet.

Ian.

Yeah, it sure is a good setup. The Audioslave (in the shop) and the recent Mojo mod using extra transistors both give even more good improvement. No-one knows when the improvements/mods will, if ever, stop