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SOHA II Builders Thread - Page 11

post #151 of 1688
I just finished the mods to allow the use of 12v 300ma heater tubes. Replaced transformer, moved the heater regulator off board and mounted it directly on the case. and jumpered out R3P.
Amp sounds great, I really like the 12BH7A tubes I am using now. Much better than the Sylvania 5963's.
I wish I had built the beefier power supply first time around, would have saved me about $50.
post #152 of 1688
If we want to use 2SC2238 output transistors do we just put them (reversed) in Q6 and Q7 and keep the other transistors the same as shown in the schematic?
post #153 of 1688
Thread Starter 
Yes.
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 #154 of 1688
Thread Starter 
Quote:
Originally Posted by grendel23 View Post
I just finished the mods to allow the use of 12v 300ma heater tubes. Replaced transformer, moved the heater regulator off board and mounted it directly on the case. and jumpered out R3P.
Amp sounds great, I really like the 12BH7A tubes I am using now. Much better than the Sylvania 5963's.
I wish I had built the beefier power supply first time around, would have saved me about $50.
Glad you got that working ok grendel. You can roll almost anything now as long as the pinouts are correct.
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 #155 of 1688
Hi,

I experimented some more with the amp, and decided to put the zeners back in. I still can't hear any increase in noise with them, and I seem to hear a slight improvement (though I may be just imagining it).

Other than that, I noticed that one pair of my RCA 5963 tubes is insanely microphonic—the other pair is only slightly so, and works much better. I've also tried Electro-Harmonix 12AU7's and Channel Master 12AU7A's, both of which I like. Surprisingly the cheap Channel Masters may even be slightly better… As I'm also testing the SOHA II as a pre-amp, the least noisy Channel Masters are now my tubes of choice for that use. I may prefer the 5963's for headphones.

I don't have any other tubes at the moment, but eventually I will test more types. I even built my power supply to be ready for the high current heaters (using heatsinks much larger than those specified, 1.6 A transformer and installed a switch to bypass R3P)… Any suggestions for tubes to try? =)
post #156 of 1688
[QUOTE=Arkku;4998811
Other than that, I noticed that one pair of my RCA 5963 tubes is insanely microphonic—the other pair is only slightly so, and works much better. [/QUOTE]

I have the same issue with 5963s - I also have two sets, one of which is definitely 'insanely microphonic' (however the microphonics reduced with burn in, but not significantly.) I have another set, nicer, matched closely and not bought of flEabay that are much better.

I have switched back to Amperex 8416 for the month, and am quite enjoying them...
post #157 of 1688
I have tried a pair of RCA 5963 (black plate) a while back too. These are indeed very microphonic.
Now I’m using a pair of GE 5963 (grey plate) in my GF’s amp and these are very good, much less (or non) microphonic.

Arkku, when you have your power supply modified to support high current heaters, you might try 6N1P-EB (black plate, double getter supporters). This is a very good sounding tube at a fraction of the cost.
post #158 of 1688
Quote:
Originally Posted by Ferrari View Post
Arkku, when you have your power supply modified to support high current heaters, you might try 6N1P-EB (black plate, double getter supporters). This is a very good sounding tube at a fraction of the cost.
Thanks for the tip, I'll be on the lookout for those. My power supply already supports the high current heaters, it's just a matter of flicking a switch to get R3P out of the way. (I installed it just to keep the regulator from running unnecessarily hot with the tubes I currently have. =)
post #159 of 1688
Quote:
Originally Posted by Arkku View Post
Thanks for the tip, I'll be on the lookout for those. My power supply already supports the high current heaters, it's just a matter of flicking a switch to get R3P out of the way. (I installed it just to keep the regulator from running unnecessarily hot with the tubes I currently have. =)
In one or other way, I have missed your post some page back.
It seems to be that you are the first person around here who has built the whole amp on perfboard.
You must have lots of patience. Enjoy the results!
post #160 of 1688
Quote:
Originally Posted by Ferrari View Post
It seems to be that you are the first person around here who has built the whole amp on perfboard.
You must have lots of patience.
Mostly I chose perfboard because I don't build things like this at all that often (indeed, this is my first DIY amp) and I wanted to put in some of my own additions while at it. I also feel a bit like an assembly worker when using pre-made PCBs… =)


P. S. I posted a shot of the cased amp in the build-pics thread. Now it's suitably finished to remain on the desk while I ponder what to do about the front panel text.
post #161 of 1688
Dude. that is seriously in a different league... quite impressive.
post #162 of 1688
Wow... very impressive indeed.
post #163 of 1688
Where can I buy a board and how much is it ?! I guess it's gonna be cheaper with the group buy ... when ?

Glassjar Audio ?!

Any help would be appreciated. Thank you!
post #164 of 1688
Thread Starter 
Yes, the boards and kits will be available from Glass Jar. Please contact Jeff Rossel.

Jeff is currently pulling things together to offer the kits. I believe they will be available towards the end of the month.
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 #165 of 1688
Just in case anyone was wondering what was happening with my build...

Finally got the extra parts I needed and finished installing everything tonight (apart from the tube sockets - still haven't made a decision about that). Decided it was too late to do any testing so that will have to wait until tomorrow.
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