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SOHA II - Super SE Hybrid - Page 2

post #16 of 707
Runelight for my education what is the downside to a tube with non-matching triodes? I imagine that the current thru both sections has to be the same but the resting p-k voltage will be different, what does this lead to ?
post #17 of 707
Quote:
Originally Posted by regal View Post
Runelight for my education what is the downside to a tube with non-matching triodes? I imagine that the current thru both sections has to be the same but the resting p-k voltage will be different, what does this lead to ?
The real question is how to test the tubes for matched operation in this specific circuit. I've had a fair number of conversations with various tube vendors over the years and those whom I trust most have almost always advised against any sort of matching service (to their own financial detriment, I might add). Their reasoning is this, most tube testers that do matching are going to test the tubes at radically different operating points compared to how the end user might. And given that tubes are not a linear device there is no guarantee that tubes that test as "matched" will perform as such in-circuit. Of course this means that the converse is also true, tubes that don't test as matched might very well perform just fine in a particular circuit.

At least that's the layman's explanation that I've put together, I'd love to hear from more knowledgeable folks.
post #18 of 707
Thread Starter 
n_maher, this is is all quite true. In this case, even more so as tubes are not likley to be tested at 40V on the plates.

I probably shouldn't have even commented on this because the TUBES DON'T HAVE TO BE MATCHED IN THE FRONT END.

regal, i am happy to answer this at a later time. Digi01 (why he keeps following me around I cannot figure out) has posted to the Headwize thread offering to make boards. So far I have not posted any schematics so he can't do that and I was about to post some further circuit information to explain some of the amp's innards.

Because of Digi's post, no further explanations for a while. Sorry.

Now perhaps some of you guys can get Digi out of my hair by insisting that you won't buy boards from him if he once again hijacks my work.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #19 of 707
I didn't realize there was such a fiasco with the original SOHA boards, sorry to hear that.
post #20 of 707
Is SOHA II == Stacker II?
post #21 of 707
No SOHA II SE is a completely new amp, it uses a low voltage power supply and is all incorporated onto a single board with a compact footprint. Stacker II is a modular HV hybrid that is propotionally more complex..dB
post #22 of 707
Quote:
Originally Posted by runeight View Post

Now perhaps some of you guys can get Digi out of my hair by insisting that you won't buy boards from him if he once again hijacks my work.

count me in to only buy "real" boards, from designers or authorized sellers...
post #23 of 707
Quote:
Originally Posted by vixr View Post
count me in to only buy "real" boards, from designers or authorized sellers...
I double that.
If there qill be a GB for the "official" boards, I'll definitely use that opportunity just so it wont be necessary to get Digi's boards on a later time. Although I still don't consider my current SOHA 100% ready, I can't miss by any means the building of SOHA II.
post #24 of 707
Quote:
Originally Posted by runeight View Post
regal, i am happy to answer this at a later time. Digi01 (why he keeps following me around I cannot figure out) has posted to the Headwize thread offering to make boards.
digi still doesn't seem to realize, or accept, that what he did was unacceptable behaviour. I think it would be fantastic if everyone would post that if they are going to build this board, they will only use boards officially sanctioned by runeight.
post #25 of 707
Runeight, does this have a similar sound sig to the original soha + Jisbos?

I have just wired up my jisbos and the difference in sound (fuller, more powerful) is fantastic, even over a good opamp (2107)
post #26 of 707
I will only build with an official board, from a sanctioned seller.
post #27 of 707
runeight & dBel84, thanks for sharing this new amp!

I have noticed that there are 3 OpAmps on the SOHA II board. The one on the front belongs to the ε12 circuit (?), then there are 2 other OpAmps on the left and the right of the board, does it means that the output buffers included an OpAmp based DC servo circuit, similar to the one used in the CK²III ?
Btw, where is the relay of the ε12 circuit mounted? (arggg... I can't find it on your pic , dB).
post #28 of 707
I'm not even done with my SOHA + JISBOS, can't you guys slow down?!

I will respect the wishes of the designer (who is, after all, kind enough to share his designs) and only use approved boards.
post #29 of 707
Quote:
Originally Posted by Ferrari View Post
Btw, where is the relay of the ε12 circuit mounted? (arggg... I can't find it on your pic , dB).
my bad for not taking new images after I had it all tested and working. These were earlier images and had not been fully stuffed. So yes, relay and then some is missing. Interestingly, this amp does not suffer the start up / shut down transients that we have experienced with other hybrids. I think the e12 circuit is still a good idea as it will protect the headphones in case of failure or behaviour different from this build and it is a small price to pay in terms of additional components. The opamps are not in the signal path and are indeed part of the servo/e12..dB
post #30 of 707
Thread Starter 
adamus, I don't know about the sound compared to the SOHA/JISBOS. Only dBel84 has a version of the amp at this moment. I guess one or two of you intrepid builders might have to build one and then compare.

But, there is no surprise that putting a discrete buffer on the SOHA significantly improves the sound. This was my next step before the amp was hijacked.

Ferrari, the other two opamps are indeed for the output stages. But they are isolated from the AC signal paths by 1M resistors. They will not influence the signal. In the picture that dBel84 has posted, the relay is not mounted yet.

MoodySteve, I've got even more designs lined up behind this one.

Many thanks to each of you who has agreed not to buy "unauthorized" boards.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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