Wanted. Simple EL34 Push Pull Design

[revintage]

0.2% second is not (IMO) a huge problem. Open loop, that's pretty darn good

I totally agree. But is there anything but open loop to consider😉?

But remember, Zout is 510k so loading might have been a problem!

 

[SY]

Without meaning to offend, this is why cathode followers exist!

In any event, cascode, no measurable odd order. Time to revisit your prejudice. 😉

 

[revintage]

Without meaning to offend, this is why cathode followers exist!

You don´t think it is offending to fingerpoint the obvious?

Without meaning to offend, aren´t you making things overly complicated.

The threadstarter asked about a simple amp!

About prejudice I have earlier mentioned that I use a patentable variation of cascode+CF(ECC88+half ECC83), called TULP) in my guitaramps. They works wonders there and have given me good reviews in Swedish magazines.

No matter how they measure it doesn´t tell if they sound good!

As much as you like cascodes I don´t like them nor CFs in HiFI equipment.

It´s a matter of opinions, not about predjudice😉 .

 

[revintage]

SY,
Just joking about offending etc., but if you want to argue more feel free to E-mail me.

Came to the insight that we are ruining Jacks thread if we go on with this discussion here.

 

[Doug Kim]

Searching for the simplest PP possible, transformer input must be the way to go!

If using a transformer-balanced out preamp the input transformer should be eliminated.

This adds a cost of up to £100 depending on transformers choosen. As this is a British request from the beginning, Sowter might be the choice.

I have almost everything for this design lying around. Has anyone tried this design, or has any opinion on it?

 

[kmtang]

Simplified Williamson EL34 PP

I built a pair of EL34 PP based on Williamson W5M design. It has no NFB and now using Lundahl LL1620AM-PP OPT. It has excellent sound that I ever heard with highs and mids matches with my SE amps.

Johnny😀

p.s. the two resistors at EL34's cathode should be 5-ohm instead of 50 ohm.

 

[tinitus]

It has excellent sound .....

with expencive NOS tubes, or...?

 

[rmyauck]

Johnny,

Thanks for posting that!

What did you use for driver tubes? 6SN7?

 

[roline]

I did a simple single sided toner transfer PCB using 6JT8 driver tubes and 6L6-KT88 output tubes. It was a joint project with Kegger, he asked if I would be interested in this project, his idea for the driver tube being low cost and available. I spent over 6 months playing with different tubes, caps and output iron and B+ combinations.......
The lowest cost was 6P3S Russian tubes with 8K-8 20watt output iron. B+ was about 360V for the 6P3S tubes. The final experiment used 6550 Svetlana outputs with 480V B+ and Hammond 60watt 4.3K iron. This is what was build up in the final amp.
The objective was an amp that could be built by a beginner, low cost. The PCB allows for jumpers in the B+ string if caps do not need to be stacked. That helps to keep the cost down on the lower voltage B+ 6P3S version.

 

[kmtang]

I use two 6J5 as driver and EH EL34 for power. You may use 6SN7 for the driver and phase splitter stage.

Johnny

 

[kmtang]

First I use the Peerless output transformer came with the W5M kit. Unfortunately, it wasn't sound right to me. Then, I put the Lundahl LL1620-PP and it had much better performance. However, the vocal wasn't sweet at all unless I play with some latest CD music. I use Lundahl's amorphous core OPT for my single ended amps and I thought how would it make the difference with amorphous core OPT in PP amp. Then, I persuade my very best friend to buy a pair of the LL1620AM-PP for each of us. After I got the AM-PP OPT, I put that in, and wowhhhh, it sound so lovely with very finite details like SE amp and slamming punch bass.

The Williamson design of the power stage bias helps in reducing the distortion and balancing of the two tubes.

 

[kmtang]

Photo

this is the one I am listening.