OK, here's a new point to point layout for the 40db folded version.
Should get started this week. I plan on using 20 AA batteries initially, then go to a Salas shunt or super reg once I know it's working.
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When there is a go I'll probably follow you. Just as a test to fill my time
I had a quick look but I'm not the designer so I let him speak.Regards
Thanks Salas. I will look at getting C6 closer to the input stage.
So, using R12 as a pot...what Iam I looking for when adjusting? Just even voltage between channels after the trimpot? Would 1/2W 200R or 500R pot be OK here?
Thanks!
Another FSP goes live
I finished a temporarily boxed test of my FSP today and all seems well so far. I only let the smoke out once in the process, so trust me on this, never hook up raw B+ backwards (despite checking it 3 or 4 times). It definitely kills an LED or two ;-)
My line voltage is regularly ~121-122vac so I used the Antek AS-1232 instead of AS-1236, yielding ~45V raw DC, 36V at the rails when adjusted for 3.6v TP2-TP1. I had plenty of adjustment range.
This version is set up for maximum gain for my fairly low output Soundsmith Hyperion CL moving iron cartridge, and I used fixed loading with a 1k TX-2575. This is the unique cartridge Peter Ledermann builds with the cactus needle cantilever (naturally tapered). Normal loading is 1k-2k, which is a bit unusual for most phono stages. I've found 1k works quite well. The 2SK369BL's are running about 9.3ma on 5.1 ohm R2/3 and 12ma IDSS. I used the 2SA970BL's for Q3z. Caps are Clarity MR 2.2uf output coupling, ESA 4.7uf Zobel, and V-Cap CuTf 47nf interstage coupling, though I may still opt for a 100nf CuTf with more listening. I trimmed the C2/C2y RIAA to 15.2nf with styrenes, using a DE-5000 LCR to match them. The rest is mostly Tea-Bag's very nice mini-kit.
I bought a 2U Slimline - Chassis on the DIYAudio store and planned to mount the main boards in there. My test box is about the same size and even with the PS and toroid in the same box, I can't hear any noise when cranked up. I planned to case the raw dc supply separately, but now I'm wondering if I should just put it all in the new case and be done with it. I did note that it took almost 2 hours to stabilize in this big non vented case, even with the lid on. Once TP2-TP1 reached 3.6-3.7v, it pretty much stayed put.
It's too early to make meaningful comments about the sound, though it obviously provides fine detail, plenty of body, and is very clean sounding. My previous phono stage was the Zesto Andros PS1 tube preamp, which received consistently great reviews and performed quite well here. Unfortunately it's long gone now, so I can't compare other than from memory, but I have no doubt the FSP could at least hold it's own with it.
My system:
- Trans-Fi Salvation rim drive TT, T3Pro air bearing linear tonearm, slate plinth, magnetic bearing update, silver direct wiring from cart clips to male RCA's
- Soundsmith Hyperion II CL cartridge (~0.3mv)
- Bent Audio Tap-X balanced preamp (uses 4 SlagleFormer autoformers)
- Acoustic Imagery Atsah monoblock amps (Hypex NCore 1200)
- TAD Evolution One speakers (Andrew Jones coax design)
Many thanks to Salas for developing this and sharing so freely and to Tea-Bag for PCB's and putting all the hard to get bits together. He runs the best group buys I know of anywhere, always responsive to my many questions. I'm looking forward to a more stylish and functional re-box and much more vinyl listening pleasure ahead.
John Scofield and Pat Metheny "I Can See Your House From Here" on Blue Note is playing now...
Tom
I finished a temporarily boxed test of my FSP today and all seems well so far. I only let the smoke out once in the process, so trust me on this, never hook up raw B+ backwards (despite checking it 3 or 4 times). It definitely kills an LED or two ;-)
My line voltage is regularly ~121-122vac so I used the Antek AS-1232 instead of AS-1236, yielding ~45V raw DC, 36V at the rails when adjusted for 3.6v TP2-TP1. I had plenty of adjustment range.
This version is set up for maximum gain for my fairly low output Soundsmith Hyperion CL moving iron cartridge, and I used fixed loading with a 1k TX-2575. This is the unique cartridge Peter Ledermann builds with the cactus needle cantilever (naturally tapered). Normal loading is 1k-2k, which is a bit unusual for most phono stages. I've found 1k works quite well. The 2SK369BL's are running about 9.3ma on 5.1 ohm R2/3 and 12ma IDSS. I used the 2SA970BL's for Q3z. Caps are Clarity MR 2.2uf output coupling, ESA 4.7uf Zobel, and V-Cap CuTf 47nf interstage coupling, though I may still opt for a 100nf CuTf with more listening. I trimmed the C2/C2y RIAA to 15.2nf with styrenes, using a DE-5000 LCR to match them. The rest is mostly Tea-Bag's very nice mini-kit.
I bought a 2U Slimline - Chassis on the DIYAudio store and planned to mount the main boards in there. My test box is about the same size and even with the PS and toroid in the same box, I can't hear any noise when cranked up. I planned to case the raw dc supply separately, but now I'm wondering if I should just put it all in the new case and be done with it. I did note that it took almost 2 hours to stabilize in this big non vented case, even with the lid on. Once TP2-TP1 reached 3.6-3.7v, it pretty much stayed put.
It's too early to make meaningful comments about the sound, though it obviously provides fine detail, plenty of body, and is very clean sounding. My previous phono stage was the Zesto Andros PS1 tube preamp, which received consistently great reviews and performed quite well here. Unfortunately it's long gone now, so I can't compare other than from memory, but I have no doubt the FSP could at least hold it's own with it.
My system:
- Trans-Fi Salvation rim drive TT, T3Pro air bearing linear tonearm, slate plinth, magnetic bearing update, silver direct wiring from cart clips to male RCA's
- Soundsmith Hyperion II CL cartridge (~0.3mv)
- Bent Audio Tap-X balanced preamp (uses 4 SlagleFormer autoformers)
- Acoustic Imagery Atsah monoblock amps (Hypex NCore 1200)
- TAD Evolution One speakers (Andrew Jones coax design)
Many thanks to Salas for developing this and sharing so freely and to Tea-Bag for PCB's and putting all the hard to get bits together. He runs the best group buys I know of anywhere, always responsive to my many questions. I'm looking forward to a more stylish and functional re-box and much more vinyl listening pleasure ahead.
John Scofield and Pat Metheny "I Can See Your House From Here" on Blue Note is playing now...
Tom
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Hey Tom that's a nice build and thanks for the informative post with thorough breakdown of the build and system details. Congratulations.
Those Antek trafos have magnetic shield so if there is no hum in a large box its OK having it there. Do a simple test of moving it half a meter outside on some wooden plank along all AC wiring while focusing on resolution level before you decide there will be no second box nonetheless. But let it play for 48 hours meanwhile.
Also good to see that the standard grounding scheme embedded in the PCBs works for you too.
That is a high resolution home system in the pics situated in a pleasant room with some acoustic treatment. Let us know your final phono tweaks with time.
Those Antek trafos have magnetic shield so if there is no hum in a large box its OK having it there. Do a simple test of moving it half a meter outside on some wooden plank along all AC wiring while focusing on resolution level before you decide there will be no second box nonetheless. But let it play for 48 hours meanwhile.
Also good to see that the standard grounding scheme embedded in the PCBs works for you too.
That is a high resolution home system in the pics situated in a pleasant room with some acoustic treatment. Let us know your final phono tweaks with time.
The jung reg, boards from the diyaudio store. Ive built it before....thats why Iam considering it vs. The Salas shunt. It would be easy for me to build.
It has begun. Hopefully I dont screw it up too badly...
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The other day I finished replacing R1, R2, R13 to lower the gain slightly, Monday night I got the bias settled, and last night I had a brief listen (had some work to do so couldn't give it a long session). The gain is certainly still adequate. In terms of sound quality I can't say much yet, there may be no difference, but I certainly liked what I heard. My first impression was a slight improvement, better channel balance, and a sense of improved "solidity". I'll give it a better evaluation later.
My first impression was a slight improvement, better channel balance, and a sense of improved "solidity". I'll give it a better evaluation later.
Salas,
I have said this a few times over the past few months.
Can you provide corroboration?
or have you discovered this for yourself and your own measurements?
I thought it was a bit easier, slightly less thermal effect. On the other hand, Sunday night was warm, and I roughly set the bias. Then checked it again on Monday, when the weather was cooler, and it only got up to about 3.2V (vs 3.6+). So it still takes a couple of hours to stabilize, but I think it's a little more stable. It does not drop to <0V when cold like it did before, but then it's not as cold as it was when I built it back in the winter.