[Sathimas]

How big should the inside of a Standard SOHA II case be? (in cm please)

I payed mine today and hope that it won't need much longer
than one week to get to Germany (think I'll have to collect it from the customs anyway.)

But I could allready start building the case, material will be wood.

 

[holland]

Is anyone running this amp with 4mA tail current? I'm curious as to how it affects the sound.

 

[wiatrob]

Quote:

Originally Posted by Sathimas /img/forum/go_quote.gif How big should the inside of a Standard SOHA II case be? (in cm please) SNIP But I could allready start building the case, material will be wood.

Depends on if you want the transformer inside the case or not. The 'Enclosure' page on the website has some PDF's you can use to plan sizing:

The SOHA II Headphone Amplifier

Or you could start with the dimensions of the recommended Hammond 1455T2201BK case:

Hammond Mfg. - Extruded Aluminum (Metal End Panels) - 1455 Series Enclosures

 

[wiatrob]

Quote:

Originally Posted by holland /img/forum/go_quote.gif Is anyone running this amp with 4mA tail current? I'm curious as to how it affects the sound.

I've cranked my original build up to at least 3-4mA, but my tin ears did not detect a difference - can't recall which tubes though...

May try again with the build on my bench awaiting casing...

 

[kostalex]

Please, advice tubes-rolling for SOHA II > Denon D2000.

Music are jazz, blues, old rock and rock-n-roll. Ears are 60 old.

 

[runeight]

I have tried quite a few tubes. My favorite so far is an RCA 5963. If you like a more mellow sound the Amperex 8416 is my next choice. It is a 12V 6922.

 

[holland]

I've tried a few tubes too. I agree with runeight, depending on your preferences (and headphones used). I use black plate RCA 5963, very microphonic so you have to find a pair that isn't.

5814A may do well also.

 

[kostalex]

Is matching pair necessary?

 

[Hayduke]

@Kosta

My favorites so far have been the 6DJ8's but I'm not done trying out my 6 different tubes I ordered

Also I'm using HD650's so I can't really say for sure how they will sound with your Dennons.

In regards to matching tubes, I believe Alex has said it's not necessary with this design.

 

[mdabro]

Another Soha

All is almost ok, sounds very nice, but I have one question: I can set only 120-210mV on R10L and R10R. Is it enough?

 

[Ferrari]

Quote:

Originally Posted by mdabro /img/forum/go_quote.gif Another Soha All is almost ok, sounds very nice, but I have one question: I can set only 120-210mV on R10L and R10R. Is it enough?

Congrat with your successful build!

Probably parts tolerances are playing a role in this case, however… 120mV - 210mV across R10L and R10R correspondent to approximately 55mA – 95mA quiescent current at the output devices. This should be sufficient for (almost) any kind of headphones!

 

[mdabro]

Ferrari, can I use E88CC instead 5963 ?

 

[Sathimas]

Started my build today with the case ... the Amp itself went on his way today from Jeff.
Hope it arrives until the beginning of next week so that I can finish it until sunday, my fathers birthday.

 

[runeight]

Quote:

Originally Posted by mdabro /img/forum/go_quote.gif Another Soha All is almost ok, sounds very nice, but I have one question: I can set only 120-210mV on R10L and R10R. Is it enough?

I think that Ferrari is right. It may just be component tolerances that all went in one direction.

But there are a few things you should check. Are the rails +/-15V?? Are all of the resistors in buffers the correct values? Are you using the stock BD transistors or something else?

210mV is enough for almost anything that you'll want to do. I'd just like to see you have more range on the high side of the setting.

 

[TimJo]

I'm about to order parts for my build and have a couple of questions.

Mouser is backordered on a couple of parts.

One is the high voltage regulator. I took a quick look through the catalog and it looks like TI is the only one making this part - is that right Alex, or does Mouser have an alternative selection that I missed? I may need to order it from Digikey I guess. It will be my only Digikey part.

The other one is the UF4004 diode. I am going to use this one instead - unless you think I shouldn't. UF4004-E3/54

Also, I noticed that on the SOHA II bom, C3E is a polar cap, but on the CTH bom, it is bipolar. Can it be bipolar here as well?