I already used a 5K Poti in my previous preamp and according to the text from Nelson Pass in Bosoz it gives the best performance and the best frequency response.
One question:
what kind of transformer do we need here?
The 2 secondaries are not symmetric.
I will be using these trafos with double screaning, isolation between secondary and primary, magnetic and electrostatic screaning.
If we order more than 5 pieces we can order them custom made.
They are from www.schuro.de and cost 33,00 Euro for 65VA.
One question:
what kind of transformer do we need here?
The 2 secondaries are not symmetric.
I will be using these trafos with double screaning, isolation between secondary and primary, magnetic and electrostatic screaning.
If we order more than 5 pieces we can order them custom made.
They are from www.schuro.de and cost 33,00 Euro for 65VA.
Attachments
My negative supply rail is -20V DC, but it isn't necessary to go that high. I wouldn't go any less than -10V DC, and suggest -12 to -15V DC as a reasonable range for great performance.
I wanted to play with various power supply configurations and see what results I could get, so I left my self with extra voltage to play with just in case I needed it. I am currently running dual mono supplies, with separate discrete soft recovery diode bridges for each rail, followed by a CRC filter with 10,000uF per rail, plus a discrete voltage regulation stage. That then feeds into the RC filter in the gain circuit. The result: absolute dead silence with the volume control at maximum, and fantastic channel separation. This supply is just plain silly overkill, but for me it was kinda like climbing Everest, it did it because it could be done.
I must admit, now that I have seen Kari's boards, I wish I'd got in on the GB so I could rebuild it all pretty like, instead of the perfboard version I have now.
Cheers, Terry
I wanted to play with various power supply configurations and see what results I could get, so I left my self with extra voltage to play with just in case I needed it. I am currently running dual mono supplies, with separate discrete soft recovery diode bridges for each rail, followed by a CRC filter with 10,000uF per rail, plus a discrete voltage regulation stage. That then feeds into the RC filter in the gain circuit. The result: absolute dead silence with the volume control at maximum, and fantastic channel separation. This supply is just plain silly overkill, but for me it was kinda like climbing Everest, it did it because it could be done.
I must admit, now that I have seen Kari's boards, I wish I'd got in on the GB so I could rebuild it all pretty like, instead of the perfboard version I have now.
Cheers, Terry
Yes, if you include the cascode, you have the circuit I used, which I can't rave about enough although I suspect I am somewhat biased towards my own creation. However, I have had a few friends audition it in their systems where it displaced units costing a few thousand dollars, and had quite a time getting mine back. A couple of those people have hounded me since to build one for them, but I told them they'd either have to go buy a Pass Labs preamp or build one themselves. I am within striking distance now of having my Aleph-X's finished and I can't wait to see how they integrate with my preamp.
steenoe said:We are in the same boat, TerryJust finished the mechanical work on mine. I did mount all the hardware also, so only the connections are missing. Take a look at these monstrous things
Steen
Hello Steen, those look good for about 120 Watts Class A each in Mono config, is that about right?
Regards
Anthony
Thats about right, Anthony. I go for 2x100 watt's, biased as hard as my wall-outlet will permit
I am getting tired, dragging those amps around My back is starting to hurt Hope to finish them soon. I have to admit that the A-x's isnt excactly the easiest amp I have built
I almost thought they were gonna kill me, arrgh
Steen
DaveM said:
Well, Dave, I'm finding myself very, very busy these days, most likely too busy to take care of the GB myself, at the moment. However, Mikkel is a very articulate and seemingly reasonable man which assures me that anyone willing to set up the GB will have no problem dealing with him, he seemed very willing to help when I made the initial inquiry. Also, Mikkel has been volunteerily checking in on my project's progress. One of only a handfull of people I've ever dealt with to check in on their customers after the sale.
BTW, I've recently tested the kits I've received from Mikkel (basically, the kits form a complete, passive pre-amplifier) and everything works as it should, I'm a little tempted to keep it as a passive pre based on its current performance but the Zen-aleph needs more gain for full out rock sessions
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