M25/sissysit construction
I am a scrounger and dumpster diver. Have used many recycled parts in my builds including an ACA amp enclosue made of only recycled heat sinks(pic). After following this thread and seeing the mighty ZM' s t-bed example, I was inspired. Thru the years I have accumulated a lot of stuff, mostly good stuff. So I dug thru the pile. Found what is a possible donor for reviving. A AR D-52 and a set of Zelman CPU cooling sink fans.
Two issues yet to be resolved. The original beautiful copper shielded bifilar transformer will deliver a solid +-21v using the 240v primary wiring on 120v. Is that going to be enough to get operation on track, or what is the consequences. Secondly, the distance to the input transformers to this power transformer center is, I expect about 8in/20cms. Is this distance great enough to reduce hum interference?
I am a scrounger and dumpster diver. Have used many recycled parts in my builds including an ACA amp enclosue made of only recycled heat sinks(pic). After following this thread and seeing the mighty ZM' s t-bed example, I was inspired. Thru the years I have accumulated a lot of stuff, mostly good stuff. So I dug thru the pile. Found what is a possible donor for reviving. A AR D-52 and a set of Zelman CPU cooling sink fans.
Two issues yet to be resolved. The original beautiful copper shielded bifilar transformer will deliver a solid +-21v using the 240v primary wiring on 120v. Is that going to be enough to get operation on track, or what is the consequences. Secondly, the distance to the input transformers to this power transformer center is, I expect about 8in/20cms. Is this distance great enough to reduce hum interference?
Attachments
I expect input xformers are going to be too close to beastie ...... however , let's hope that 240Vac primary , fed with 120Vac will work in our interest , so ...... cunning plan to try it
ook the zalmans , ,they're small
use 2 pcs of 12cm fans , scavenged from newer PS PSUs , or bought surplus
with two ditto on heatsink , maybe you can manage even with 5 or 7V on them
and , oh yeah - great destiny for AR chassis
ook the zalmans , ,they're small
use 2 pcs of 12cm fans , scavenged from newer PS PSUs , or bought surplus
with two ditto on heatsink , maybe you can manage even with 5 or 7V on them
and , oh yeah - great destiny for AR chassis
Highly appreciated useful audio test's !
Look forward Chromenuts on your music reproduction discoveries
Fans
Ok, I dug thru the pile, more fans. The plan was to remove the black fin segments of the heat sink(8 segments are screw to the back plate) and install a Zelman speed controlled fan heat sink to the back of each mosfet, heat transfered thru the back plate to the bottom pad of the Zelman. Each Zelman was rated at 95 watts max, fan running. There is speed controls for the fans allowing some type of temp control. Is there an optimum operating temp for the mosfets?
Is there a way to cover/shield the input transformer? Could those transformers be bypassed if the preamp has 25-30 db gain(audible Illusions)?
Ok, I dug thru the pile, more fans. The plan was to remove the black fin segments of the heat sink(8 segments are screw to the back plate) and install a Zelman speed controlled fan heat sink to the back of each mosfet, heat transfered thru the back plate to the bottom pad of the Zelman. Each Zelman was rated at 95 watts max, fan running. There is speed controls for the fans allowing some type of temp control. Is there an optimum operating temp for the mosfets?
Is there a way to cover/shield the input transformer? Could those transformers be bypassed if the preamp has 25-30 db gain(audible Illusions)?
Attachments
first of all - I believe you're familiar wit saying - there is no replacement for displacement ... in other words , dozen of sissy fans are hardly going to replace two proper biguns
or - they will , but your ears gonna bleed , not mine
second - Audible Illusions's 25-30 db of gain are utter drek , comparing to Cinemag's 12db
you'll get better sound with 10K pot in front of SissySIT , than with that .....
they should better call them Audible Delusions .........
or - they will , but your ears gonna bleed , not mine
second - Audible Illusions's 25-30 db of gain are utter drek , comparing to Cinemag's 12db
you'll get better sound with 10K pot in front of SissySIT , than with that .....
they should better call them Audible Delusions .........
sissysit
Fortunately I'm not a Hemophiliac, and the red you see in the AI is not blood but biasing leds.
What would be a good distance separating the power transformer and the input transformers. I could lengthen the side panels to increase the seperation.
Fortunately I'm not a Hemophiliac, and the red you see in the AI is not blood but biasing leds.
What would be a good distance separating the power transformer and the input transformers. I could lengthen the side panels to increase the seperation.
better to try with actual channel pcbs in , then moving things apriori
we can't predict how big/strong magnetic field you'll have with that thing on full throttle
regarding Audible preamp ..... I sorta got carried away , hope you didn't took it personally 🙂
though , still thinking the same ........ simply because tube line stage with ECC88 can sound way better than that , besides being much better adjusted to nowadays sources and power amps , regarding gain etc.
we can't predict how big/strong magnetic field you'll have with that thing on full throttle
regarding Audible preamp ..... I sorta got carried away , hope you didn't took it personally 🙂
though , still thinking the same ........ simply because tube line stage with ECC88 can sound way better than that , besides being much better adjusted to nowadays sources and power amps , regarding gain etc.
thanks
No worries, the AI has had many surgeries. I would have to put it back to where it started from to get that gain back anyway. I do have a Elma 10k attenuator, and will give it a try!
It's all for fun!
No worries, the AI has had many surgeries. I would have to put it back to where it started from to get that gain back anyway. I do have a Elma 10k attenuator, and will give it a try!
It's all for fun!
What I heard is that Nickel is better for sensitive small signal but opposite for bigger signal swing. So the price of BMCF version is high... 🙂
ZM & friends, would it be possible to drive the autoformer directly from something like a DCG3, bypassing the jfet buffer?
I was watching Nelson Pass BAF talks, and he seems to imply this might be the case, as long as the pre has the current capability to drive the autoformer circuit.
I'm interested in trying it out at some point, since i'll most likely use the DCG3 as a preamp(and to drive HPs). I think i'd have to switch the jfet buffer out of the circuit, probably at the transformer, right?
I was watching Nelson Pass BAF talks, and he seems to imply this might be the case, as long as the pre has the current capability to drive the autoformer circuit.
I'm interested in trying it out at some point, since i'll most likely use the DCG3 as a preamp(and to drive HPs). I think i'd have to switch the jfet buffer out of the circuit, probably at the transformer, right?
yes, omit input buffer , if you have enough Cojones in preceding stage
just take care of practically zero DC going in xformer ....... meaning - preceding stage must have minimal DC offset , stable in time
it is extremely convenient , in fact , on Babelfish M25/SissySIT pcb - there is a 2pin jumper header , intended for exact purpose of measuring/setting input JFet buffer offset , having them (buffer and xformer) connected after setting said offset
so , remove jumper , connect your signal route on second jumper pin , ditto to xformer
just take care of practically zero DC going in xformer ....... meaning - preceding stage must have minimal DC offset , stable in time
it is extremely convenient , in fact , on Babelfish M25/SissySIT pcb - there is a 2pin jumper header , intended for exact purpose of measuring/setting input JFet buffer offset , having them (buffer and xformer) connected after setting said offset
so , remove jumper , connect your signal route on second jumper pin , ditto to xformer
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I believe that I'll start next weekend building one complete SissySIT , followed with proper photo-strip and some explanations ....... so pretty much everything will be covered
Interesting that AI came up. I have a 2D. To demonstrate how much of a bottom feeder and audiofool I am, it is a piece of equipment I would strive to best. A “reference” as the wordy golden ear experts would put it. In combination with an old used Counterpoint SA12 and KEF 104/2 speakers it has been one of the best all around sounds for me. Yes, it did not do things my DCB1 with gainclone or ACAs can do with full range front horns...but it was nice.
it is nice , when made by Greedy Boy , while learning all things , including toobz
however , it is not nice when actually bought for not peanuts money
but ...... situation is that there are much more mediocre tube preamps around , than good ones
however , it is not nice when actually bought for not peanuts money
but ...... situation is that there are much more mediocre tube preamps around , than good ones
