MPP

The beayty of the current feedback of the monster is the fact that you inject the feedback in the same devices thta works with the signal....the gem is af very traditional design with a ltp input/feedback configuratio. I am100% confident that the monster current feedback type holds much greater potential....it has simply much less smear and far greater clarity..
 
Ricardo, the relays are for switching between the driven cascode and conventional ground refferenced cascode. We found that the driven cascode has more slamm and definition in the bass. Well, inside of the 8W it can throw around.
I find the GEM unusual, but honest i do not get the point.
MiiB. one advantage of current feedback is that when a heavy signal hits the feedback node it is not limitted by the constant current of a long tail pair, hence the slew rate is much higher.
 
........... I even had designed a SUSY amp based on power Opas. I have given that circuit to Brianco but again karma struck, preventing Brianco from finishing it..............

:eek::eek::eek:

I think Moira is a better word!

Pleased to say that I can walk again and that my heart is working normally (for me). I have most of the parts for the OPA amp in the house now and just as soon as the few remaining parts, including a power transformer, arrive I will hope to be able to get the amp built.:) I have a very simple but enormously strong box now drilled and tapped awaiting a front panel and final polishing + anodising! I also need to build a buffer pre into the case.

Like Joachim I too had early power amp mishaps - with a hybrid Radford TT-100 in my case , and again later with a 211 SET amp. (I sometimes wonder if the shock I received then [:xeye:] was responsible for my arrhythmia problem).

@Joachim,

What is the power requirement for the Sonics speakers which I have? [The room is about 140M3, and is not too live.]
 
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I think 2 x 10W can be very loud, even with normal sensitivity speakers like yours.
What counts more is speed and resolution. Current delivery into complex impedance and independence ( well that is not that easy ) of the feedback loop from back EMf is also important. Some amps perform very poor when you connect a speaker although they measure great on the bench. Your OPA SUSY should be quite capable because of the double diffential feedback structure. Earth disturbance is also not intruding much because of the topology. My problem is that i lost the original schematic because my I-Book was stolen during High End in Munich. I hope you have a hard coppy, Brian.
 
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Thank you Joachim, I was a little afraid of low power in such a big room, but some SETs I had in London would make a LOT of very clean sound. I have the schematics for the OPA Susy and will send them to you now.....in fact I thought that I sent them a few days ago.

The house is a converted farm building - the 'listening' room is very big and the whole thing is a headache because the original architect 'forgot' to get correct permissions to turn it into a house. But the room sounds quite good compared to the small house we had in London! And the salmon fishing near here is the best in the UK...and that is my major outdoor sport. The other main advantage is that houses are not expensive.