carpenter said:Hey Morten, I'm off topic, but this is about your speciality, so it's OK...
Tell me more about your big chokes--you know, the pretty ones. How much do they cost to make? Resistance, inductance? Please brag, cause from what I remember, you deserve too.
They're bifilar wound, right?
I'm learning that with my choke loaded, differential follower arrangement, a neg power supply can push current through any resistance. Just have to keep that resistance low in order to keep the neg power low and the choke cool.
And best of all: current sounds good through a mosfet--lots of current!
All these years, I have not been running enough current, not nearly enough!
Slightly intoxicated Magura:
They have become cheaper to make, as the copper price has gone down. As is, I would guess they're like 500usd a piece.
The resistance is according to my intoxicated memory 2R4 DCR.
2 x 90 mH a piece.
Yes, they're bifilar wound.
Before you get too excited about them, I just want to mention, that they're +40 lb a piece, and about the size of the wheel of a beetle.
Magura
And the fact that your hands will be pretty sore for a few days after winding them
Thanks, you too.
Last picture I built the Drek into an old Luxman 2x80 watt'er integrated, and used the heatsink from it. By bolting too small pieces of alu (heatsinks actually) underneath it, created an area to mount the fets to. Worked out pretty well, regarding the heat. The supplies are for now two Twisted BosoZ supplies, set up for +/-36V.
Last picture
I built the Drek into an old Luxman 2x80 watt'er integrated, and used the heatsink from it. By bolting too small pieces of alu (heatsinks actually) underneath it, created an area to mount the fets to. Worked out pretty well, regarding the heat. The supplies are for now two Twisted BosoZ supplies, set up for +/-36V.Attachments
steenoe said:Thanks, you too.
Last picture
ya see - what's good for someone's amp , is barely enough for crazy Metaldanske preamp
well - you certainly deserve even heavier and crazier Drek .
Attachments
Magura said:
...and about the size of the wheel of a beetle.
Magura
And the fact that your hands will be pretty sore for a few days after winding them
Good Lord; I remember, now. Perhaps there's a way to wind up a choke on a quality metal core? Not to mention, I don't have a thousand bucks to spend on an amplifier.
Way off topic: Earlier, I mentioned current... my fourteen gauge feed wires get warm after three songs. I'm going to get larger wire.
Just a little off topic: Know where a guy can get his hands on some good laminations?
Got a foot of snow, yesterday and today. Pretty crazy stuff for my neck of the woods. Normally we're lucky to get more than an inch or two.
carpenter said:
In your place, I'd look for an electro-mechanic workshop gone south. There you can get the copper for reasonable money.
Alternatively I would guess that you're not getting a much better iron core choke, than your toroid transformers.
carpenter said:
Unless you're talking about insanely lousy wire, heat is not an issue. A 14g is good for much more than you will ever need.
carpenter said:
Any transformer manufacturer will happily sell you a core.
Magura
steenoe said:Thanks, you too.
Last picture
So Steenoe, did you trip over the LAN cable?
Magura
It sounds fantastic There is still some things to modify, like rebuilding the supply to Shuntreg's and so on, but this preamp has more potential than I would have though. The dynamic's are simply tremendous, and soundstage , details and so on, are the usual Toshiba J-fet business Simply great stuff. The outputswing and gain are much too much for my U.P's so I lowered the gain to about the half, which is still too much. ZM, what are the possibilies to run this thing at lower rail voltages to give it some more relaxed working conditions? Without any penalties, soundwise ofcourse.
There is some noise with the gainsetting used in the schematic, it was less when I lowered the gain. (Sort of hissing, windy noise)
There is still some things to modify, like rebuilding the supply to Shuntreg's and so on, but this preamp has more potential than I would have though. The dynamic's are simply tremendous, and soundstage , details and so on, are the usual Toshiba J-fet business Simply great stuff. The outputswing and gain are much too much for my U.P's so I lowered the gain to about the half, which is still too much. ZM, what are the possibilies to run this thing at lower rail voltages to give it some more relaxed working conditions? Without any penalties, soundwise ofcourse.There is some noise with the gainsetting used in the schematic, it was less when I lowered the gain. (Sort of hissing, windy noise)
steenoe said:It sounds fantastic
There is some noise with the gainsetting used in the schematic, it was less when I lowered the gain. (Sort of hissing, windy noise)
naah .......
I can see from what you wrote that you have doubts .......
anyway - it have worse CMRR and ripple rejection than
, because Pumpie is more symmetric ....... and Drek's chokes are perfect path from hiss flowing from supply to output , collecting it also to gates ;put some chokes somewhere in both neg and pos supplies and find what's difference .
I can bet that his is solely from PSU's
regarding voltage - I think that you can go down to +/- 20V , and to half current through outputs , comparing to what you are using now .
double increase source resistors for outputs (22E) for that , and re-set .
another one - to increase stability - put 22k to 33k ditto from both 369 gates to gnd .
you can do that easily from copper side .
you can also try BC546B as cascode elements , instead of 170s ; Metaldanske was responsible for that ........
" I have fets in my junk , but I don't have small bjts ....... can I put 2N3773 there ...?"etc.
I told you - that was really b-day present !
not ordinary one .
blame Metaldanske .
seems that he really luv ya .
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