SE 20W. What tube?

[ErikdeBest]

a little threadjacking

As further contribution I can suggest that 6080's in parallel A1 ultrafeed and paracoupled can sound mighty good and can be set up without paying full fare for an expensive outoput xfmer like a Lundal. I am slowly working on just such a 20+ watt design on the bench now which employs four bottles per channel (8 triodes in parallel) and it sounds fabulous although only the output stage has been prototyped so far.

RCAvictim, can you post a schematic of the prototype? Many thanks!

Erik

[rcavictim]

Originally posted by agent.5
i am currently building one with eimac 250tl

also you may consider using gm70 tube and take a look at the site gm70



http://groups.yahoo.com/group/GM70/

Thanx, that was the Euro version of the 813 without the plate cap I couldn't recall the name of.

[rcavictim]

Originally posted by ErikdeBest
a little threadjacking





RCAvictim, can you post a schematic of the prototype? Many thanks!

Erik

Sorry, nothing drawn up yet.

[ErikdeBest]

Sorry, nothing drawn up yet.

Then there is no other option than waiting a bit

[rdf]

Isn't the GM70 a near-845 equiv? It's a triode. The only 813 sub I recall was the Russian GU-13, another top cap tube and now unobtanium.

[rcavictim]

Originally posted by ErikdeBest


Then there is no other option than waiting a bit

Don't wait for me if you want an amp in your lifetime. I started this amp project with a fury about three years ago, even making my own output toroids. I got a circuit breadboarded after much trial, change, trial, etc. Then the working prototype has sat abandoned tying up a entire workbench in the lab now for almost three years. I have too much on my plate.

[rcavictim]

Originally posted by rdf
Isn't the GM70 a near-845 equiv? It's a triode. The only 813 sub I recall was the Russian GU-13, another top cap tube and now unobtanium.

RDF,

You are probably right and I was mistaken apparently about this one.

I had a quad of 813's and have been looking for them now since the last move almost ten years ago without success. I am looking for some good used 813's if anyone has spares they will part with free or cheap please let me know. They won't be re-sold, I just wanna play.

[Hojvaelde]

Hello

Thanks friends. I got a lot of input to my brainstorming.

I think it must be a 813 based amplifier. 845 need 1500 Volts and a lot of driving power.
The EL509 based amplifier is to small. Sorry.

What about PSE screen dreven EL509. Is that a problem?

Regards and thanks

Benny

[rcavictim]

Originally posted by Hojvaelde
Hello

Thanks friends. I got a lot of input to my brainstorming.

I think it must be a 813 based amplifier. 845 need 1500 Volts and a lot of driving power.
The EL509 based amplifier is to small. Sorry.

What about PSE screen dreven EL509. Is that a problem?

Regards and thanks

Benny

Is the reason he wants you to build him an amp because you offered to save him $$$$ that way? The reason I ask is because for in the $1500.00 range you can now get very sweet SE triode integrated stereo amps from China that use the 845 and also the more powerful 805.

I have just such an 805 amp and although heavily modified in the power supply it retains the original audio circuit. I absolutely love the sound, and the command of the bass that comes from the big reserve of power on tap (40 watts/ch.).

The 813 SE ultralinear amp design I mentioned is not a triode and as a pentode will have a different harmonic signature to a pure triode with higher levels of higher odd order harmonics. The UL config makes it look electronically more like a triode than a pure pentode but there is still a difference. This sound may not be to your friends liking. It would be a shame to go to all the trouble to build something and end up with less than what is desired. I really like the simple implementation offered by a SE UL 813, but have not yet had the chance to build and evaluate one for myself. Some folks have and there are various articles about it on the internet.

Having said this, the much loved 6BQ5/EL84 is also a pentode and in SE can sound quite fabulous when matched to the right speaker, so like anything else in the end you may have to just try it and see. If there is one thing I know that is an absolute fact, in tube audio one cannot merely grab an amp at random, and a speaker system at random based on wattage or efficiency ratings and expect the best sound, but as happens often a synergistic combo may be found that is a match made in heaven and the results are magical. This is what drives us tube-o-philes, me anyway.

[Hojvaelde]

Hello Bob

No not to save money. I am very interrested in tubes.
I am working 9 to 5 with microprocessores and components in size 0402 and 0603.

To build tube amplifiers is relaxing for me. I have build 3 RIAA and a Dynaco Mk III clone.

I know I want to build a 813 based SE amplifier to my self. My only problem is now to designe a chassis i wood/alu I am satisfied with.

Regards

Benny