[ServinginEcuador]

Dreamslacker,

Do you mind sharing exactly how, and what you used, to bias those op amps into class "A"?? I am looking at doing the same for my AD843 and 825 op amps. I have looked at doing the resistor across pins 4 & 6, but didn't like that idea too much.

 

[Dreamslacker]

Quote:

Originally posted by ServinginEcuador Dreamslacker, Do you mind sharing exactly how, and what you used, to bias those op amps into class "A"?? I am looking at doing the same for my AD843 and 825 op amps. I have looked at doing the resistor across pins 4 & 6, but didn't like that idea too much.

Using the cascode JFET configuration as stated in Tangent's META42 article.

http://tangentsoft.net/audio/meta42/tweaks.html

You might want to download the schematic for the META42 to get the idea of where to put the 2 JFET's and resistor.

You'll still need to hook the resistor + 2 Jfets between the pin 6 and 4 of your opamp (I'm assuming single opamp IC). This configuration would be much better than just a resistor alone though.

I used 2N5457 & 2N5459 N-JFETs as the 5484 & 5486 are not available in Singapore. (Or at least the shops I buy from)

I might also be changing the EL2001CN buffers in my amp to stacked HA3-5002 buffers (2 per channel). Hehehee...

 

[ServinginEcuador]

SCHWEET!! Thanks for all the info and part numbers. Now I just have to figure how I can incorporate this into my CDP!!! I already modded it with some IC sockets to play with the sound thru chiprolling it, now I would like to see what all the hype is about when it comes to bias changing those same op amps!!

Thanks again guys for making this site worthwhile and a community eager to help each other out!!!

 

[daycart1]

Quote:

Originally posted by Hirsch IMO the MicroZOTL is a stunning accomplishment. It's very dependent on getting a good tube set to hear what this amp can do. However, once you've got the tubes, it's simply fantastic. If Berning had put it in a fancy case, he could have charged double the price, and it would still be a great value

What?? It *IS* a fancy case. Or maybe it just grew on me...

 

[markl]

Xtop,
I just loved my ZOTL, but I found it a bit dull with HD600 (but, then again, to me the HD600 is a bit dull inherently). Nevertheless, it was clean and pleasant but not as lush or as dynamic as in combination with the Earmax Pro.

OTOH, once I got my hands on a pair of Sony CD3000s, those really really loved that ZOTL. That's one fantastic combo and worth considering as a mate for your ZOTL if you too find it too reserved with the HD600.

Congrats on the ZOTL, it's a great amp!

Mark