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SOHA II Builders Thread - Page 20

post #286 of 1686
Quote:
Originally Posted by FallenAngel View Post
As promised, a few comments on SOHA+JISBOS vs SOHA2 (both with GE 6680 tubes).

I'm been listening to the SOHA+JISBOS at work for hours on end and the SOHA2 at home. Tonight I have them side by side, both fed off a simple diyMod (Sonicap Gen1 output) and listening using MarkL modded D5000 headphones. I chose these headphones because they're very detailed and the "brightest" I have to try to catch all the nuances and faults of my music. I listen to a lot of music from French R&B (Jenifer, Koxie, Kenza Farah) to Rap (WuTang, 2Pac, Immortal Technique, Eminem - non-radio stuff, that stuff sucks) to rock (Linkin Park, Korn, System of a Down) to pop/dance (Kelly Clarkson, No Doubt, and even threw on Britney Spears for good measure).

Both amps sound great and I really enjoy them both, but having them this close together and listening to the same song with both, the differences are clear.

As some of you you know, I've been dealing with some background noise issues on the SOHA2 prototypes (yes, it's actually on both and when I let the amps warm up for a good 30 minutes, the noise is almost non-existent but still just barely there - definitely not something I notice when listening to music, even through the quiet parts).

So on to sound comparison.

First off, I have to say the SOHA2 is a speed demon! The bass (where it's most noticeable) is sharp, hard-hitting and very precise. The SOHA+JISBOS is a little slower and "mellower".

Bass (continued): More prominent in SOHA2, just a very good quality punch or rumble (when the song has it) instead of what I hear in the SOHA+JOSBOS which is a more mellower drawn out bass line. Certain victory for SOHA2 for my music taste, and I love strong bass, I just don't want to be overwhelmed.

Mids : Again the mids on the SOHA2 come out to the front a little, more in-your-face than the SOHA+JISBOS. You might say that SOHA2 is more analytical in the mids and it's easiest for me to think of SOHA2 as a strong classical singer while the SOHA+JISBOS is a more of a sultry jazz voice. Depends on mood to which I would prefer at the time; I would usually go for SOHA2.

Highs : The highs seem more sweet in the SOHA+JISBOS. I would not say the SOHA2 is less detailed, it's not, but the top end does sound sharp (I am trying to avoid using the world "clear" because there is no muddying of the highs at all in the SOHA+JISBOS, the SOHA2 is just more "sharp", perhaps even leaning to shrill with some instruments).

Note separation: SOHA2, no question. I'm pretty much note-deaf and I hear the instruments with this amp, not just a generalization of which notes they produce. The only other amp I hear that with is the Beta22.

How everything works together : Both amps have their (as I learned only today) distinct sound signatures. I think both are really great amps and I am enjoying both; choosing one isn't something I would want to do.

I will not have a final answer to which is better/worse, nor will I write a "conclusion". I like both, I'm very likely to keep both and use both regularly.

I will leave this note though: for Sennheiser HD600 & HD650, the SOHA2 is a clear winner.
Thanks FA for the nice review. What transistor did you installed on your SOHAII output stage? Stock BD139 or else?

I think they have their own color like tubes. Would be interesting to know if you have the same installed on your SOHA's JISBOS.
post #287 of 1686
Thread Starter 
Let me add my thanks to FA for the review.

One thought about the HF of the SOHA II. This feature of my amp is quite dependent on the tube. The 5963 have crystal clear highs whereas the 8416 (a 12V 6922) have a totally different character. OTOH the 5963 are very microphonic and the 8416 are not.

If you have time to roll some tubes you might (or might not) see similar changes.

One thing about the SOHA II is that you can roll different tube types, not just different versions of the same tube.
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 #288 of 1686
BTW I just ordered yesterday a kit from Jeff @ Glass Jar Audio. I'm eager to start it.
I will customize it a bit by changing the default PS+Audio channels electrolytic caps and buffer stage BJTs.

I just wish there would be more interest to runeight's custom front and rear panels (from FPE) that fit the recommended hammond case.
post #289 of 1686
Thread Starter 
Just to check one more time, is there anyone else interested in these FPE panels?
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 #290 of 1686
I like the idea of the panels, but I didn't get around to ordering the kit yet, so I didn't want to say yes yet...that, and I'm not thrilled about them costing >$50. How much interest has there been in them so far?
post #291 of 1686
Thread Starter 
There has not been that much interest. Less than 5 people so far. I'm not, by any means, trying to push these on anyone. I am just trying to help those who may not want to do the casework. My panels were very easy to install and use, particularly the rear panel that has the power inlet, switch, and input jacks.

But I think we need at lest 10 individuals to express interest before we order these so that we can at get the volume discount for 10 items.

Anyone else?
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 #292 of 1686
I might be interested.
post #293 of 1686
So the kits are around 200 + over $50 for the face plates? So $250 USD to build a SOHA II? That is not so good with the current exchange rate to Aus $. Wish I had bought a prototype kit earlier!
post #294 of 1686
runeight:

i'm trying to build this out of parts I have on hand. I think the 18K plate resistor is probably the one value I cannot substitute for, per your excellent write-up.. perhaps I can use a zener here instead? I have 15K resistors though. can I use 15K for R16? Also, R5 and R11 can vary slightly, such as 2.7K and 680 for R7? If so, yay for me.
post #295 of 1686
Thread Starter 
Quote:
Originally Posted by luvdunhill View Post
runeight:

i'm trying to build this out of parts I have on hand. I think the 18K plate resistor is probably the one value I cannot substitute for, per your excellent write-up.. perhaps I can use a zener here instead? I have 15K resistors though. can I use 15K for R16? Also, R5 and R11 can vary slightly, such as 2.7K and 680 for R7? If so, yay for me.
Yes on all counts. The zener will introduce a bit more noise, but you may not hear it. The only other possibility is that you might not be able to dial up 2mA tail current with 2k7. But, I'm pretty sure that that won't happen.
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 #296 of 1686
The build has begun...







post #297 of 1686
Nice start! I love these red Wimas. Will you use some boutique parts? I don't know if I'll replace C1s.
post #298 of 1686
your workspace...it's sooo clean. wow.

Good start. You're going to really enjoy this amp. It's very nice.
post #299 of 1686
Quote:
Originally Posted by wolf18t View Post
Nice start! I love these red Wimas. Will you use some boutique parts? I don't know if I'll replace C1s.
For C1L/R I'm going to use a VitQ .22uF and C5L/R a Muse ES 470uF and then I replaced all the original BOM amp film caps with Wima's. For the PS section I went with all Nichicon UHE, UFW, UPW wherever possible.
post #300 of 1686
Looks like you are using Vishay Dale RN60D for R7L/R (620Ω). Was it not available as RN55D? or resistors from other brands (BC, Panasonic, Xicon) with the same size as RN55D? Nice start, BTW.
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