[tomb]

Interest check on Steinchen's discrete buffers for the SOHA:
http://headwize.com/ubb/showpage.php?fnum=5&tid=2362

Although not strictly analogous, this should be the SOHA version of the Millett DB's in terms of the ultimate sound quality option for the SOHA. There are several circuit options, including a couple that will drop-in to the small space on the Digi board. He has some suggestions on tweaking the Digi board/SOHA design as well.

Highly recommended - so, please cast a vote for your preferences.

 

[FallenAngel]

Nice! Just posted, thanks tomb.

By the way does anybody know where to get the 2SK170 and 2SJ74 transistors in Canada? 2SJ74 is on 90+ day backorder from Newark.

Oops, sorry, didn't read the original thread, 2N3819/2N3820 are available from Newark.

 

[makasin]

Thanks for the post!
I am going to go spend more money $$$, thanks headfi!

 

[steinchen]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif By the way does anybody know where to get the 2SK170 and 2SJ74 transistors in Canada? 2SJ74 is on 90+ day backorder from Newark. Oops, sorry, didn't read the original thread, 2N3819/2N3820 are available from Newark.

please note the pinouts:
2n3819 SGD (turn 180°)
2n3820 DGS
2sk170 DGS
2sj74 DGS

 

[headphonejunkie]

Great!! Now I can get the best there is out of my soon to be SOHA.

 

[bhjazz]

Aw geez, more? (haha) Yeah, I'm in. I have so many projects backed up now, I might as well plan just a little more for the Soha. I do find it interesting that many amps discussed here later get an option for some kind of upgraded buffer. Neato!

 

[tomb]

Yep. If you've ever heard Steinchen's Millett DB's, though - worth every penny and effort.

By the way, these buffers can be used pretty much in any amp where a unity gain output stage can be used.

 

[bhjazz]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Yep. If you've ever heard Steinchen's Millett DB's, though -

Are you referring to the DB group buy that Nate did last summer? If so, then I have a couple of those boards ready to be built...

 

[mb3k]

Steinchen noted that the dDB's should only be used with the CCS in Mu-follower mode only. I would assume more people have their SOHA's with MOSFETs in the standard CCS config, so I guess the Jisbos buffers is better suited...

 

[tomb]

Quote:

Originally Posted by mb3k /img/forum/go_quote.gif Steinchen noted that the dDB's should only be used with the CCS in Mu-follower mode only. I would assume more people have their SOHA's with MOSFETs in the standard CCS config, so I guess the Jisbos buffers is better suited...

That is certainly true, but there may be many boards yet unbuilt. Also, it's only adding a couple of jumpers, then unsoldering 4 resistors and the LND150's.

Perhaps what should be considered: if the current demands are the cause for "outrunning" the current to the tube, thereby requiring the mu-follower, then the DB option is the raging bull choice.

I will no doubt buy a few of each, regardless, but am already disappointed that the SMD DB has lost.

 

[headphonejunkie]

I just purchased mosfets. Do you mean I cannot use these now? or do I have to set them up differently?

 

[tomb]

No. The MOSFET's (LND150) are best for both versions of the CCS supply. It's simply a rearrangement of the CCS circuit for higher current-demanding output stages. Refer to the Library article and Digi's walkthrough - it's highly documented. Before Steinchen's buffers, the only occasion to use this was for BJT opamps, which are not stable in many of the traditional DIY amps. It seems most are not even unity-gain stable - such as the AD8397.

None of this applied to the typical FET opamps such as OPA2134/32, OPA627, OPA551, AD8610, etc. So, with a couple of exceptions, the subject has not come up very much.

 

[headphonejunkie]

Phewww! I will have to do some research before I start the build.

Thanks

 

[FallenAngel]

I thought there is a simple jumper on Digi's board for CSS choice.

 

[headphonejunkie]

I just read that a lot of peole had to wait a while to receive their boards. Does that mean I am going to have a bit of a wait for mine?