Twisted X Overture

[Russ White]

Hi Max,

It will not be long now, but I am still doing some experimenting with another version of this circuit that I think (well actually know, as I am listening to it now!) will be very, very, cooool

Look for a new thread soon...


Cheers!
Russ

[cjd]

Geeze Russ... do you slow down? Can you lend me some of your project/play time?!

Do me a favor and continue using a "basic" circuit around the chips themselves, and I will be able to try your variants very quickly indeed (once I source parts) since I went the modular approach... Yet another reason to have done that!

C

[Carl_Huff]

Russ,

I really like the simple elegance of your circuit. My only concern is the imput impedance. 2.2k seems awfully low to me. Has that been a problem? Do you know what the power out is into 8 ohms?

[Russ White]

Carl,

Yes the input impedance is 2.2K, and no it has not been an issue for me, but I am using a preamp which can easily drive a load down to say 500ohms or so. I am using my Twisted Sibling preamp. I also have it DC coupled since I know there is no DC on my source.

Alternately you could simply take a good opamp such as the AD8620 and use it as an instrumentation amp in front of the THS4131. That will get you very high input impedance.

You can read about Twisted Sibling here:
Twisted Sibling - THS4131 based preamp/buffer/SE-BAL converter


Cheers!
Russ

[Carl_Huff]

Russ,

Have you thought about what it would take to double up on the LM3886's to double the power output?

[Russ White]

Originally posted by Carl_Huff
Russ,

Have you thought about what it would take to double up on the LM3886's to double the power output?

Carl,

Stay tuned. I have thought it through extensively. I have something I will post soon. For now you may enjoy reading this:

http://www.diyaudio.com/forums/showt...344#post940344

That should do 100-150W into 8ohms without any problem.

Cheers!
Russ

[cjd]

It won't like my speakers though. 2.9ohm nominal.

C

[Russ White]

Which one?

The 4702 circuit I linked to a couple posts ago would handle that without a blink.

[tiltedhalo]

Am I missing something?? this looks like a balanced line driver circuit , you know a "A typical bridged amp" not super symmetrical looks to have a common feedback loop to the LM and the THS/OPA? if not please explain how it works???

[Russ White]

Originally posted by tiltedhalo
Am I missing something?? this looks like a balanced line driver circuit , you know a "A typical bridged amp" not super symmetrical looks to have a common feedback loop to the LM and the THS/OPA? if not please explain how it works???

TI Licenced Nelson's Super Symmetry patent in there design of the THS4131. By nesting the feedback of the output stage with the fully differential input stage I gain all the benefits of the Super Symmetry.

Search the forums for more info on Super Symmetry. It is pretty cool stuff.

The results so far have been very very pleasing.

Cheers!
Russ