The SOHA II Tube Thread
May 5, 2010 at 7:28 AM Post #91 of 99

Nevohteeb

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Hello everyone,

I finished my SOHA II amp two days ago, using them with a pair of 12at7 from Telefunken that I got for free at work and a Sennheiser HD535 that I own for 16 years now and still work perfectly. Nevertheless, I'm not really happy with those tubes, so I'm looking for another pair.

Quote:

Originally Posted by holland /img/forum/go_quote.gif
eh 12au7 nice well rounded sound, aggressive, yet behaved. works great with my choice of music, primarily death and black metal.


Quote:

Originally Posted by bmwpowere36m3 /img/forum/go_quote.gif
I've used:

* Electro-Harmonix 12AU7's

Listened with Senn HD580's and to music ranging from Pink Floyd, Led Zeppelin to Metallica, Alice in Chains, In Flames, AC/DC, to some classical. The EH tubes at first were a little harsh and very in your face, forward soundstage. As they burned in they've settled back, but still have a forward presentation. They have clear, defined highs, good midrange punch, and bass detail. I'd say the only thing they lack is maybe some more bass slam and midrange bloom, however like Holland has mentioned they sound wonderful paired with "Metal".



Metal (Death, Black, "extreme"), classical (operas and symphonies) and Pink Floyd are what I listen to the most. So, according to the comments above, I should try to find a pair of EH 12au7.

There are some on ebay, for reasonable prices, but there are several versions : black box, gold box... Which ones would you recommend?

Moreover, as I said, metal is not the only kind of music I listen to, so will those tubes match my other tastes?

Thank you very much for you answers.
 
May 5, 2010 at 12:58 PM Post #93 of 99

Nevohteeb

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Hello,

Quote:

Originally Posted by regal /img/forum/go_quote.gif
There is a SOhaII tube rolling thread here


I read the 6 pages, and it seems that both Holland and bmwpowere36m3 enjoyed the EHs for metal music.

Did I miss another rolling tube thread?
 
May 7, 2010 at 9:00 AM Post #94 of 99

regal

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Quote:
Hello,

Code:

Code:
[left] [/left]

I read the 6 pages, and it seems that both Holland and bmwpowere36m3 enjoyed the EHs for metal music.

Did I miss another rolling tube thread?



No I just wanted to make sure you knew about the thread to be an educated consumer :)  Actually thought I was posting on the SOHAII builders thread,  with the chaos of the format change I'm all confused.
 
May 8, 2010 at 4:16 AM Post #95 of 99

Nevohteeb

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Quote:
No I just wanted to make sure you knew about the thread to be an educated consumer :)  Actually thought I was posting on the SOHAII builders thread,  with the chaos of the format change I'm all confused.


No worry. :)
I always read as much thread as I can before I ask something. Here, I read two people saying that the EH 12au7 are good for Metal music, but I wanted to have a little more feedback.
 
I bought a brand new pair of EH 12au7 for a very good price, so we'll see :)
 
May 22, 2010 at 11:40 AM Post #97 of 99

regal

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Yea I think Alex didn't put it on his website because it can be more difficult to setup.  I recommend you plug in a space heater to the outlet you intent on using the SOHAII and checking mains AC voltage at that receptale,  to see if the voltage drops more than 10V's,   Some old houses and rural power company's have this problem and you fight E12 dropouts,  the cure is just to lower B+.  The mod is worth it IMO.
 
Quote:
Luv it!  Wish I would have read this thread about the mod first though...it would have been a lot easier...



 
Mar 17, 2012 at 2:03 AM Post #99 of 99

Navyblue

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Quote:
Here's how to get the most of your tubes on the SOHA II. The issue I was hearing on some of the 12AU7s and 6DJ8's was a slight weakness or thinness. So here is how you can safely get more current thru the tube:

1. Set B+ to 85V
2. Add another 18k ohm resistor on top (parallel) of R4L&R (makes it 9k ohm)
3. Add another 200 ohm resistor on top (parallel) of R6L&R (makes it 100 ohm)

Adjust P1L&R to give .550 V across R6L&R

Check to make sure you have at least a 19V drop across the top CCS (adjust P1 until you do)

This gives 2.75 mA thru each tube section.

Now the Mullard 12AU7's has pulled ahead of the 8416's. All the tubes I have been working with are sounding better.

I think the original design of 1 mA per tube section is too low and a remnant of the old (pre TL783) PS design. The amp is competing with what I breifly remember my Stacker II sounding like. The biggest improvement is in bass definition (i.e. telling the difference between the bass drum and the bass guitar.)

.


Can anyone tell me, if I just install half of the value for R4 and R6 right from the start, would 1/8W resistor be sufficient? Or would I need to for 1/4W? This would be a mild problem since the board is so cramped.
 
Thanks.
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