diytube.com

soundbrigade wrote:Don't drop it because I wrote something negatively, I've got 3-5 other disgns that are less "complicated". I can fix schematics for you tomorrow.

Thanks for the schematics. It will be fun to swap 12B4 with1626 using some DIY socket adapters.

Is that the EL84 board you have been talking about, Shannon? It will be fun build. I plan to make it 8BQ5/10BQ5 SET..with appropriate heater windings tx. It will be awesome to make use of some cheap NOS 8BQ5/10BQ5.

katabatic wrote:I've now completed my version of the 6bm8 amp (Ed's one on the right). I used a Hammond 369x power transformer, Edcor GSXE 10-8-5k output transformers, and Soviet-era 6f3p tubes. Coupling caps are Russian K40-Y-9's.

That's some very professional looking point to point wiring you've got there. I wish I could lay out an amp like that, but alas it still hasn't clicked for me. I finally did finish my 6BM8 amp, but it looks more like the poster child for what not to do when building a tube amp.



I assure you it does play, despite my sloppy solder slinging. I finished it up just a few hours ago, and only a few years from when I started. Maybe I'll spend some time listening to it this week and develop some impressions. I was able to grab a few quick voltage measurements at a slightly reduced line voltage. Feeding it 115VAC, the B+ landed at 207 VDC. B+ supply for the AF section came in at 184 VDC. The front end cathodes measure 1.2/1.3 VDC, and the pentodes' cathodes were at 15.1/15.0 volts.

I'll try it again a little later with "normal" line voltage and see how it goes.

Ty_Bower wrote:
I finally did finish my 6BM8 amp, but it looks more like the poster child for what not to do when building a tube amp.

I assure you it does play, despite my sloppy solder slinging. I finished it up just a few hours ago, and only a few years from when I started.

Ty,

That all looks OCD perfect. It takes an artist and a surgeon to work a layout like that.

I don't know what's worse, taking 2 years to complete a build or 2 years to get started, as I did. And mine looks like everyone's 2 day old, dried out, pot of leftover spaghetti.

Thanks. :)

Here's a shot of it running, just so you know I'm not making it up. Kids, mind the exposed high voltage on the tops of those transformers, if you please. I really ought to cover that up.

Just use some shrink tubing on the primary's solder tabs, that is sufficient to insulate the HV out of the way of curious little fingers, and inquisitive pets.


I started another compact sized amp, physically very similar to the12B4A SET on the left side of the photo:





The main differences is that it will use EL84s and a 12AT7, in a mutant variant of the "RH84" design.
Power trannie is the Antek 05T-240, I used the 220V tap for an approx 325VDC B+. Filter caps are 270 uF and 390 uF, with MUR4100A s in the FWB rectifier.
Got the power supply in the "tub" completed, and tested, and finished all the drilling and punching for the top cover, and mounted the OPTs, speaker binding posts, RCA inputs and volume control - and then, right on schdule, my back went "out" on me again, so it's all on hold until I can feel better and more able to work at the bench...

The other difference is that I mounted the round neon-illuminated power switch on the front of the "tub", rather than on the back as with the 12B4A, with the LED plot lite on the front. Just using what I have handy in the junque box.

/ed B

Hey, Ty, your amp is beautiful, top and bottom! Sounds good too, doesn't it? Love the big power tranny; I remember when you originally posted pictures of the work-in-progress, how awesome it looked. And let me again thank you (and Ed) for posting the schematic and construction information. Couldn't have built mine without you guys!

https://picasaweb.google.com/1095707775 ... 7274292898
SE 1625 & C3g & EDCOR 20 w, 3 kohm, 8 ohm.
Very special and awesome sound. Today I finished it.

azazello wrote:https://picasaweb.google.com/109570777566485968551/Amplifiers#5864139187274292898
SE 1625 & C3g & EDCOR 20 w, 3 kohm, 8 ohm.
Very special and awesome sound. Today I finished it.

I love seeing 1625 amps. Thanks for the pic and report.

Shannon

Amazing tubes C3g are gift from Magnus.....I think, they are from the best pretubes. Tanks, Magnus!
/1625 in UL, C3g - in triode mode. I something don't like black box, I had very short time to make this SE for Bulgarian audiophill meeting after week, where I want to demonstrate this amazing sound/.

6AQ5s and 6HG5s are basically slightly whimpy 6V6GTs, in a smaller package, same operating characteristics, slightly lower max plate voltage and dissipation. Also available in 12V and 5V filament versions, as with the 6V6GT family.

12AB5 is another 12V6GT / 12AQ5 equivalent, just in a 9 pin miniature with the same pinout as a 6973, and the 6CM6 is the 6.3 volt filament version of 12AB5..
The "industrial" version of the 6AQ5 is the 6005.

In the days of the metal 6V6s, there were some of the "lesser" tube manufacturers, who would rather sneakily hide a 6AQ5 inside of a metal 6V6 octal package,
it had a 7 pin to octal adapter built in.

The somewhat unique Russian 6P1P / 6П1П has similar op-chars to 6V6 / 6AQ5, but there is no direct USA produced plug-in replacement. Don't know if there is an
ELXX version

/ed B

Das versione europico della 6AQ5 sont EL90, to speek multilinguage. It's, electrically and pinoutly 100% compatible.

...

My little bit more than low wats projects, finished 2 years ago:
https://picasaweb.google.com/1095707775 ... 4731452706 - SE 6S33S
https://picasaweb.google.com/1095707775 ... 0803460258 - SE 6S33S

My best sounding Amplifier OTL, OCL 6AS7G General Electric /direct coupled to speakers/ in front. Band is 5 - more 50000 Hz with the same amplitude +-0 db. /PS is in black box/.
Small tubes are ECC88 - pretube and ECC81 - phase inverter.
Now outputs are for about 12 ohm, I will add one 6AS7G in every channel for about 8 ohm and will change 4 chocks for more current.
Speakers are Fostex 206E in hornes.
I think, I never will back to listen music with SE with OT.

My new SE-UL project with the best tubes E84L and E80CC Siemens and Telefunken and EDCOR:
https://picasaweb.google.com/1095707775 ... 4705642738
Kenotron EZ81 is in the black box on left. Cathode shunts - ELNA Cerafine, Nichicon. Caps in PSU - Rubycon. Interstage caps - Russian ФТ3 - 0.22 uF.