Mengyue/Music Angel Mini tube amp 6P1 pp

[assendor]

Oh forgot to mention,

IT would be OK if they where only horrid to get out.

Like mentioned, one did survive to be fit into the socket, other I tried Broke the tube,
glass all over me and all over the room, WONDERFUL!!!
They where aligned as well as I was capable of anyway.

EWRRREWR#("(

It's never easy, NEVER.. these tubes must be good, most of things almost impossible to get
working ARE!! HA HA HA!!.
IT's not supposed to be "just like that!"

-Jonas

[ian444]

Those flat ceramic sockets look much easier to use, thanks for the link. The caged ones look like trouble to me...

Ian.

[assendor]

Hello Ian,

Yes those flat sockets looks to be more convenient to play with.

Just assuming here, you are thinking of biasing them GU-50's with LED's ??

Just got my Blue LED's 0.5W 10mm 3.2v-3.6volt 100mA. 465-475nm.
They could be perfect for biasing something like the GU-50's.

Would be funny to try it out.
Just have to be aware of the lower resistor value from Grid to ground.
There is a higher risk of a Runaway of the tube when having fixed bias. Maybe this was mentioned before, but still important
not to forget.

Just thinking about other places LED's can find they're way into Audio Usage.
--- later..

-Jonas

[ian444]

Hi Jonas,

LED's are a constant voltage source more or less (500mV rms on the cathodes at full power 6W on the Mengyue), so maybe similar thing as fixed bias except the cathode voltage is raised above ground. I was thinking of going fixed bias with GU50, if I put a fuse in the right place then if the bias fails the tube may be saved, if not, the fireworks would be more scary than the price of a new tube. The reason for thinking fixed bias is all my amps have been self-bias or CCS under the cathode of the outputs, and the LED's were a pleasant surprise. With self-bias, all the AC flowing through a big electro, but with fixed bias - no caps. Something I have to find out in due course.

I really like the sound of the LED's in the Mengyue, but it may depend on the LED characteristic or maybe not. George Tubelab tried some high power LED's in a prototype "Simple Push-pull" and reported favourably on the sound. It's definitely worth trying, but as I said before you need a biasing scheme to make it work, in my case it was fiddle with the screen voltages in pentode mode, then when I added the mosfet source followers I put in "fixed bias" so it was adjustable for each tube. I was amazed by the strong effect of mosfet source followers, or maybe it is just in this amp. I am listening to it now, I love the sound, the kick drum, the vocals, the hi freq's, its all here and so close, no veiling. This amp is running OPT's from the year 1956 at the moment, so nothing special there. The man who sold them to me said don't expect much from them, good for a beginner...hahaha...if this is just the beginning then this is very good! It can only get better! I want to fit the source followers to another PP amp but haven't worked out ways to power the mosfet yet. I want to fit it to every amp I build or modify from now on, it's that good, until/unless I find out otherwise.

I'm not sure what to do with GU50. I don't need that much power. But at the price they go for it's crazy for me not to buy a few now for future use. A PP 80W guitar amp would be nice, or a SE, or a PP hifi amp 20W class A. I would like to build another guitar amp now with what I have learned from hifi, that is, strip out all the background noise and let the sound come through as clean as possible. It is only through listening to music through half-decent gear that I could understand this lately. All wonderful stuff, Jimi Hendrix sounds great through 1956 OPT's, I wonder what Edcors or Electra-Prints or Hashimotos might sound like

Ian.

[assendor]

Hello Ian,

OPT's from 1956, yes there is something with the 50-50's.
One or more of the engineers making TDA1545A must be a lover of the 50's or something.
He must be one of those few still hanging on to those old things like Tunes, Alnico's, paper cones,
and generally old stuff.

I just love most of the things from the 50's, it is just unbelievable how they performed back then.
It has to be because they back then made everything to last forever, to be the best, never be replaced,
to ALWAYS be the best.
Nowadays everything is made to last MAXIMUM 1.year, if it lasts longer than two years,
well then someone in the engineering department, or ALL for that matter, has to be FIRED!!!

Recycle, Recycle, If everything was made like they did it in the 50's, THEN THERE WOULD BE NO NEED
FOR ANY RECYCLE OF ANYTHING, Just Inheritance.

Sorry about that.. HA HA!!

The combo's of Monica technology, LED's, Paul Hynes, Fet's, Tubes, BG's,OS CONS, SO ON,
With the OLD stuff from the 50's seem to be A fantastic MATCH.

Biasing with LED's, Yes the fact that Pentodes here seem to be a very good combination is not to be forgotten.
It is fantastic to be able to regulate this with the applied voltage to g2.
At least this is a easy and convenient way.

-Jonas

[ian444]

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