Angela EL34 opinions please

[losacco]

Finishing up some mods to my 300b but can't stop thinking about my next rig.

I’m considering the Angela EL34. The schematic seems straight forward but requires both sections of the 6SL7 to be connected in parallel. This detail is not shown on the schematic and I’m unsure on how the circuit should look in this area.

Any info on the 6SL7 parallel connection and any observation on the entire schematic would be helpful.

losacco
opinions

[DougL]

You are talking about this, correct?
Stereo Single-Ended EL34 Hi-Fi Amplifier

The pins to be paralleled are labeled on the schematic.
Looks like 2 and 5, 3 and 6, 1 and ? (probably 8) A data sheet would quickly answer that.

Looks straightforward. I would not think it would compete with a 300b, but you may have an application.

Doug

[boywonder]

FWIW, I'm helping a friend build this amp presently. We have a 375V power supply on a separate chassis, and another matching chassis with 4 octal sockets (both organ donors from an old console), so this one looked like a good fit; easy cathode bias also.

The only thing I'm wondering about on the schema is the 25W 880R cathode R's........25W seems like overkill.

[HollowState]

Originally Posted by boywonder

The only thing I'm wondering about on the schema is the 25W 880R cathode R's........25W seems like overkill.

That presentation is so poorly drawn that even with a magnifying glass I can't be sure, but it looks like 7.5 watts.

[OneyedK]

This looks like a truly great guitar power amp...

Did a little simulation with TubeCAD.
Used the Hammond T1627SE instead of the 125ESE, wich is, imho not a hifi transformer.

Cathode resistor on the schematic is 680 Ohm and dissipates 2W, at least a 6 Watt resistor is advisable.
I would run the EL34 a tad hotter, using a 560 Ohm resistor.
Idle current (max dissipation) is around 50mA.
The 100µF cathode bypass is ok.

When the output of the powerstage is at 8 Watt, you already have 10% 2nd order distortion. At 2.5 Watt, it still is 5%.
--> without driver stage, without any form of feedback
--> this could be lower with a 3.5k or 5k transformer

This said, that's more than enough disto for an entire amp.
If you really want to build this amp, choose a different and better driverstage or you end up with a great guitar power amplifier instead of a hifi amp.

If one wants simple and SE, one should be thinking Tubelab Simple SE.

btw, a parallel connected 6SL7 could do the trick as a driver, but with more current running through its innards and anode loaded with a CCS.
64Vpp output at a nice low impedance would be nice, make sure to include some headroom...
And of course a feedback loop should be added.

Just my 2 cents...

[rock4016]

I heard this amp with KT88 (slightly modified). It did sound good enough for hi-fi, especially if you have forward sounding speakers.

It had a relaxed presentation.

You can read about the build here.
Audio Addiction: Success is Thick and Juicy!

[leadbelly]

It's always best to search; it's the best way to avoid comments from "experts in their own mind"

SE EL34 schematic HELP: from two 6SL7's to One?

Note that Tubes4e4 has built it, and he's no lightweight.

[rumad]

I have built this amplifier, only making a few changes of my own mostly in the power supply, the power cathode resistor and I used bigger iron than required. I also built it as a power amp, with no volume control, and only 1 set of inputs. I use a 12BH7 linestage preamp of my own design before it. When first built I had it hooked up to a set of 10" Tannoys. I just couldn't believe how beautiful it sounded. And this is not my first amp build. I have since made a few minor changes, such as making it switchable from triode to ultra linear. Also I have now hooked it up to a set of DIY speakers I designed as well. Two-way front slot ported small cabs, and this thing is worth its weight in gold. At this point I'm running a Sovtek 5U4G, 2 6SL7's also Sovtek, and NOS RCA 6CA7 fat bottle power tubes. My opinion? Do not hesitate, build this amp!
I can upload pics later, from home, if you wish and answer any questions I possibly can.
Good luck!
Regards, A

[fp2000]

can this amp be built with solid state rectification? and what difference would it make in the sound?

[brians7]

I love the one that Tom McNally built for me Tom McNally's Amps On his web page it is the 5 JE Labs EL-34 Single Ended Stereo Amp. He is on #9. I like it as much my Decware Mini Torri and cost half as much. Brian