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Post by sq225917 on Mar 7, 2019 21:27:08 GMT
Building this one for Tim of Velvet Vortex record cleaner fame. He managed to score a set of main boards and I've provided all the mods, PSU parts and the matched transistors, of course. It's a pretty standard build with a few tweaks. It has Texas Components laser trimmed naked foil resistors for the RIAA  and input stage bridge.  I've started doing hand wound solid silver coils for the output stage inductors, cos why not, everyone loves a bit of silver.  The power supply is the usual deal, quad rail, choke regulated, common mode input chokes and snubbers measured for the transformers.  Usual jfet substitution on the shunt and a few stability mods.  It's all going into two narrower than usual cases and Tim's asked for a front panel mounted power switch - the fucking heathen, and I'll be mounting one LED from each of the CCS for each voltage rail through the base of the main chassis so that he can see as the individual rails power up by their feint and delicate glow. |
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Post by Deleted on Mar 8, 2019 0:02:25 GMT
Always impressed with your work Simon. It's always tidy and not a spot of solder spit anywhere.
I really must get a listen to one of these at some point.
How accurate is the RIAA? 😆😆 I'm kidding btw.
Thanks for sharing your build.
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Post by antonio on Mar 8, 2019 6:31:19 GMT
Can only agree with Biggy  , your work always looks super neat. |
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Post by Deleted on Mar 8, 2019 8:53:22 GMT
My background, albeit a long time ago, is in electronics and, agreed, that's some fine looking work!
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Post by Deleted on Mar 8, 2019 9:41:54 GMT
That indeed is the work of a craftsman, well done.
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Post by sq225917 on Mar 8, 2019 14:25:37 GMT
Cheers Boys, I do like to take my time with them.
Oli +0.3db c 20hz and 17khz
It's what the punters want
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Post by Deleted on Mar 8, 2019 16:09:58 GMT
Cheers Boys, I do like to take my time with them. Oli +0.3db c 20hz and 17khz It's what the punters want Ha! Fair enough. The more accurate, the better IMO 😉 |
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Post by karma67 on Mar 8, 2019 16:41:57 GMT
as an owner of a recently built paradise i cant praise simon enough,brilliant work and attention to detail and delivered it too.(sheffield to brighton).
as for how it sounds well what can i say,its a reference phono stage. end game for me.
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Post by sq225917 on Mar 19, 2019 20:41:11 GMT
The next one nears completion. There's a good reason I hate putting these in smaller cases, the psu is a bugger to wire up, especially when providing a front panel power switch. And to top it all it only allowed for fitting small heatsinks on the Calvins which necessitated stupid amounts of hand trimming to the cascode to get them running with as much current through them as possible while staying on the right side of thermal meltdown. Job done anyway. PSU all done and dusted, Main boards to finish casing up tomorrow.  |
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Post by Bigman80 on Mar 19, 2019 20:50:00 GMT
The next one nears completion. There's a good reason I hate putting these in smaller cases, the psu is a bugger to wire up, especially when providing a front panel power switch. And to top it all it only allowed for fitting small heatsinks on the Calvins which necessitated stupid amounts of hand trimming to the cascode to get them running with as much current through them as possible while staying on the right side of thermal meltdown. Job done anyway. PSU all done and dusted, Main boards to finish casing up tomorrow. I must admit I really like the smaller case. Looks extremely slick. |
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Post by Deleted on Mar 19, 2019 21:01:29 GMT
Does putting them in smaller casework means sacrificing some performance?
I'd rather go big and ensure the performance bis maximum!!
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Post by Deleted on Mar 19, 2019 21:53:22 GMT
Are they coins of the realm? Off to the tower with you :-) :-)
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Post by sq225917 on Mar 20, 2019 15:23:32 GMT
Putting the psu in a smaller case just means having the chokes 20mm closer to each other. all other things being equal I like them spaced a minimum of 50mm.
For the main boards though, yes. I can't fit the bigger heat sinks on the output boards with the narrower cases and that means I have to drop the current driving the output devices by a smidge.
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Post by Deleted on Mar 20, 2019 20:16:26 GMT
Putting the psu in a smaller case just means having the chokes 20mm closer to each other. all other things being equal I like them spaced a minimum of 50mm. For the main boards though, yes. I can't fit the bigger heat sinks on the output boards with the narrower cases and that means I have to drop the current driving the output devices by a smidge. Nah, it would have to have the bigger case IMO. Why spend all that money and have it hand built to then nobble the performance a smidge, even if it was a microbe level. My OCD would be off the charts knowing that. |
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Post by sq225917 on Mar 20, 2019 22:34:01 GMT
They are still at the original spec as advised by the designer of the output boards, I just like them run hotter. and as you know with your B1 a lotter hotter is better.
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Post by Deleted on Mar 20, 2019 23:01:31 GMT
They are still at the original spec as advised by the designer of the output boards, I just like them run hotter. and as you know with your B1 a lotter hotter is better. Ah ok, i wasn't aware of that but yes, you are absolutely right. Hotter the better indeed. The DCB1 benefitted on every step up the mA range we went. 1.2A is as good as i can get because of the build. I'd love to see what happens at 2.5A!  |
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Post by sq225917 on Mar 21, 2019 9:30:57 GMT
It probably melts
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Post by Deleted on Mar 21, 2019 12:03:08 GMT
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Post by sq225917 on Mar 22, 2019 19:58:56 GMT
and the finished item, lid still off.  and the undercarriage lighting for each of the four psu rails.  |
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Post by Deleted on Mar 22, 2019 22:11:56 GMT
and the finished item, lid still off. and the undercarriage lighting for each of the four psu rails. Is copying the highest form of flattery? Superb work. I love those leds. Superb. |
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Post by sq225917 on Mar 22, 2019 23:00:48 GMT
They were a total pita because I left adding the trailing wires until last, literally no way to solder them in from above. Had to solder them below then reassemble. Lesson learnt for next time...
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Post by Deleted on Mar 24, 2019 8:38:57 GMT
They were a total pita because I left adding the trailing wires until last, literally no way to solder them in from above. Had to solder them below then reassemble. Lesson learnt for next time... Did you just relocate an Led from the board rather than add them additionally? I know you can pinch the feed from elsewhere but that seems like the easiest option? |
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Post by Deleted on Mar 24, 2019 8:47:03 GMT
What is the purpose of the leds inside the case?
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Post by sq225917 on Mar 24, 2019 19:37:59 GMT
I relocated one led from each side of each pcb.
The leds are all used as constant current sources, the six under the heatsink provide a constant current reference for the front end of each +/- rail on the shunt and the long strings of six either side of the heatsink provide the same, but at 2.5x the current for the back end. The CCS could have been made in a number of different ways but multiple LEDs are quieter then even the best zener voltage reference and allow you to stack them to get an optimum value.
The fact that the four that are used to illuminate the under-carriage come from the back end of the shunt means that once these are lit it's safe to drop the needle. They slowly illuminate as ther shunt regs come up to full power, so once they're lit you're good to go.
and yes, that particular brand of green led are the quietest. There's a red that's just as good but consumes lower current so needs and extra LED in the string, for which there's no provision on the pcb and some adjustment of resistors in the front end of the shunt.
After all that I'm waiting on a couple of 30r 30 watt caddock T220 case power resistors to drop the PSu down to the optimum 26.5v. SO it's unlikely to be completely finished until Wed/Thursday.
Still, all good things....
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Post by Deleted on Mar 24, 2019 22:00:04 GMT
Thanks for that, quieter than other methods hadn't occurred to me.
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Post by sq225917 on Mar 27, 2019 22:05:12 GMT
And she's off to her new home.
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Post by Deleted on Mar 27, 2019 22:31:32 GMT
And she's off to her new home. Another owner will be satisfied I'm sure. Any more on the horizon? |
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Post by sq225917 on Mar 28, 2019 11:15:45 GMT
I have one with 95% populated boards, just needs the RIAA resistors selecting and fitting. It'll need a PSU as well.
I've got two potential buyers interested in it, I think it's probably a case of whoever demo's it first will take it, that's usually the way of things.
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Post by Deleted on Mar 28, 2019 17:59:26 GMT
I have one with 95% populated boards, just needs the RIAA resistors selecting and fitting. It'll need a PSU as well. I've got two potential buyers interested in it, I think it's probably a case of whoever demo's it first will take it, that's usually the way of things. Good luck with it! Not that you'll need it. They do seem to get snapped up pretty quickly. |
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Post by Deleted on Mar 31, 2019 12:16:58 GMT
I've heard one of these a couple of times and always remarked on how lovely they sound.
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, your work always looks super neat.
