You're right about the power supply - you're trying to get +-24v when the power supply is hooked up to the preamp or phono stage. A dual 18v transformer is what you need.
I took your photo of your new phono stage and circled in red the caps that you should think about replacing. It's what I did in mine.
---Gary
Attachments
Hi Gary,
We have discussed a lot about my Fet-10He upgrades and we have exchange a few photos, as I own 2 of these babies.
The first one has been upgraded exactly as described here: Threshold Lovers - Threshold - Fet-10 HE 'competition upgrade' Level 1
including Goldpoint attenuators.
The second one has been upgraded in exactly the same way, except that the power supply is built around one hundred Nichicon Muse KZ capacitors instead of 2 big Nichicon Fine Gold.
There are 4 capacitor cards hosting the Nichicon KZ.
The transformer is exactly the same, the rest too.
But the internal Power Supply cables are NOT Teflon insulated, whereas they are Teflon insulated in the first version of the Power Supply presented on the thresholdlovers.com website.
The common point between these 2 upgraded Fet-10He is that they sound very very similar. The improvement over the commercial version is more than impressive, unbelievable, and the 2 preamps become much much better in every domain.
The question is: is there a difference between the both, provided that the 2nd P.S. upgrade is more costly than the 1st one ?
The answer is no, and if I had to chose one of the two, I would chose the less costly, although I cannot really define the sonic differences.
As I expected the 2nd upgrade to be better than the first one, I will soon slightly modify the second upgraded P.S., and the primary target is the cabling, that will be changed for Teflon insulated with UP-OCC copper.
The reason that pushes me to bring this slight modification, is that I have experimented in all my recent upgrades that the Teflon insulated cables provide better results over PVC insultaed cable (the core of the cable being of course exactly the same) in the power supplies (not talking about the ignal path). It seems a bit surprising to me, but this is what my ears said to me.
So changing the cables will be the first change.
The second step will be a change of the transformer.
I am not 100% sure, but based on my recent experimentations on other preamplifiers, I believe I will get an improvement. And if I get it, then the second Fet-10He will be better than the first one.
Hope this helps,
Nounours
Nounours,
It's good to hear from you; it's been quite a while. It's interesting that the expensive bank of many, many small capacitors is no better than a single large capacitor. But it does seem to be a reasonable result. The only advantage of many paralleled capacitors would be lower parasitic resistance/inductance. But this is a remote power supply and the resistance and inductance of the umbilical cord probably dominates over that of the capacitors. Nonetheless, I look forward to hearing about your experiments with internal wiring.
You also mention changing the transformer. I presume that you want to try an even bigger VA rating? If so, my experience has been that I continue to hear improvement up to 300VA but I haven't tried any bigger. What are you going to try?
All the best,
---Gary
Hi Gary,
You are probably right regarding the resistance/inductance of the umbelical cord, and I have already built a new one (but not yet installed) using OHNO (equivalent of the OCC) cables. I have not tried yet, but the ones who have tried to replaced the umbelical cord on the Counterpoint preamps have reported a huge improvement...
By the way, i am looking for a skilled fan (member of our forum) , who could help me with the optimization of my power supply design: if somebody is OK, just contact me by P.M.
No I do not plan to go to a transformer bigger than 300VA as it is already really big for a preamplifier.
But I plan to move from a toroidal transformer to a cubic one based on a EI circuit, and using high quality plates. I do not know how to translated this in English, but the plates are said to be heated and to have their "grains" oriented.
i have already compared such cubic transformers with high quality toroidal transformers from PLITRON in my reference DAC. Although the VA rating of the PLITRON toroidal transformers is higher than the VA of the cubic ones, the cubic ones provide much better musical results !
So my next experiment will be to replace the 300VA toroidal transformer by a very high quality Cubic one. I know a small French manufacturer that manufactures such very high quality transformers on custom specifications. I have been using many of their cubic transformers and they are stunning and pure beauties at a reasonnable cost !
Just need to find a higher cabinet for my Power Supply because a cubic transformer is bigger than a toroidal one for the same VA.
Nounours
You are probably right regarding the resistance/inductance of the umbelical cord, and I have already built a new one (but not yet installed) using OHNO (equivalent of the OCC) cables. I have not tried yet, but the ones who have tried to replaced the umbelical cord on the Counterpoint preamps have reported a huge improvement...
By the way, i am looking for a skilled fan (member of our forum) , who could help me with the optimization of my power supply design: if somebody is OK, just contact me by P.M.
No I do not plan to go to a transformer bigger than 300VA as it is already really big for a preamplifier.
But I plan to move from a toroidal transformer to a cubic one based on a EI circuit, and using high quality plates. I do not know how to translated this in English, but the plates are said to be heated and to have their "grains" oriented.
i have already compared such cubic transformers with high quality toroidal transformers from PLITRON in my reference DAC. Although the VA rating of the PLITRON toroidal transformers is higher than the VA of the cubic ones, the cubic ones provide much better musical results !
So my next experiment will be to replace the 300VA toroidal transformer by a very high quality Cubic one. I know a small French manufacturer that manufactures such very high quality transformers on custom specifications. I have been using many of their cubic transformers and they are stunning and pure beauties at a reasonnable cost !
Just need to find a higher cabinet for my Power Supply because a cubic transformer is bigger than a toroidal one for the same VA.
Nounours
Last edited:
trick question :
what is main characteristic and gain , when using high quality iron for EI cored xformers? say for output ones ?
help from a friend - main benefit , when using EI xformer instead of toroid one , is decreased bandwidth ......
so , conclusion is ...... what sort of iron you need , to maximize difference between EI and toroid xformer ?
Hello everyone. To refresh this thread...
I want to ask GaryB why he did not keep for the 10He the same design of the PSW he used for 10Hl with CLC filter?
The reason I am asking as I got lovely 10He and plan to refresh and tune it based on the DIYA advises.
Would appreciate your input.
Regards, Konstantin
I want to ask GaryB why he did not keep for the 10He the same design of the PSW he used for 10Hl with CLC filter?
The reason I am asking as I got lovely 10He and plan to refresh and tune it based on the DIYA advises.
Would appreciate your input.
Regards, Konstantin
Konstantin,
I described what I did and why I did it in the following posts from many years ago.
http://www.diyaudio.com/forums/pass-labs/193194-restoring-threshold-fet-10e-few-questions-5.html#post3626195
http://www.diyaudio.com/forums/pass-labs/193194-restoring-threshold-fet-10e-few-questions-2.html#post2722831
Feel free to experiment with different varations - perhaps you'll come up with something that sounds even better. That's what this hobby is all about. Please share the results with us if you go do.
---Gary
Gary,
Thank you very much for the feedback. But my level of competence do not allow my to create, but to do some refresh work or reproduce someone's ideas. Unfortunately....
That is why I am here looking for your clarifiction ))
I read these two topics but looks like I overlooked this statment:
"The final supply is the 300VA toroid 18v/18v to separate Fairchild soft recovery bridges (one for plus and one for minus) to 4700uf + 22000uf. I included snubbers on the transformer secondaries to damp out any diode reverse recovery noise. And I bypassed the electrolytics with 10uf, 1uf, and 0.2uf Russian military caps".
If based on you experience, the above scheme makes the best sound improvement I will follow it, only based on sottkey diodes for the bridge, and generally I do not like bypass caps.
Actually, I was lucky to buy simultaneously a Threshold DAC 1/e which arrived already, and impressed me with its natural sound.
And Fet 10He which is on the way, and I will definitely refresh it.
Also I am thinking to build a new PSU forthe both preamp and DAC, as I belive the DAC will benefit from the better supply for the analog, and separate transformer and clear supply for the digital.
That is in the plans, and I will open separate discussion for the DAC 1/e
Thank you very much for the feedback. But my level of competence do not allow my to create, but to do some refresh work or reproduce someone's ideas. Unfortunately....
That is why I am here looking for your clarifiction ))
I read these two topics but looks like I overlooked this statment:
"The final supply is the 300VA toroid 18v/18v to separate Fairchild soft recovery bridges (one for plus and one for minus) to 4700uf + 22000uf. I included snubbers on the transformer secondaries to damp out any diode reverse recovery noise. And I bypassed the electrolytics with 10uf, 1uf, and 0.2uf Russian military caps".
If based on you experience, the above scheme makes the best sound improvement I will follow it, only based on sottkey diodes for the bridge, and generally I do not like bypass caps.
Actually, I was lucky to buy simultaneously a Threshold DAC 1/e which arrived already, and impressed me with its natural sound.
And Fet 10He which is on the way, and I will definitely refresh it.
Also I am thinking to build a new PSU forthe both preamp and DAC, as I belive the DAC will benefit from the better supply for the analog, and separate transformer and clear supply for the digital.
That is in the plans, and I will open separate discussion for the DAC 1/e
FET ten/e phonostage mods and curiosities
Hi Gary,
Found a Fet Ten/e phonostage, for a fair price.
I was satisfied with the one I had (a Boozhound Lab based on the French design of l'Audiophile by Mr. Walter, Le Pacific), but the Threshold beats it easily.
It is right now 100% original, but I will make some mods, starting with the power supply, probably in a larger case with a quite bigger tranny, more capacity (I have plenty of Mundorf 6800uF) and of course fast recovery diodes.
Next step would the stage itself. Beside the mods you made (tantalum, electrolytes), I'll replace the 10uF coupling caps, which Nelson liked to use in other electronics (I have a Threshold Fet One series II preamp, which had the same).
I've got excellent results with the Mundorf EVO Silver.Gold.Oil.
By analysing the schematic that you attached in the beginning of your thread I realised that the balanced output isn't a real balanced one... pin 3 is connected to the ground via a 10uF and two 220 ohms resistors. Guess I don't to replace this 10uF which is the same polyester type than the one where the signal goes through (C113).
But it's curious design: two EQ networks in parallel, then summed through R108 and R116, then through a single coupling cap.
This "balanced" output: what benefit would it have. I'm not using it, because my preamp doesn't have a balanced input, just curious.
Another curious thing was that I set the four gain switches to MC... and had very little gain with my low output cartridge, when switched to MM the gain was there?!?
Anyway, if you have a couple of minutes to comment on my comments, it would be nice. Via PM as well if you wish.
Best purchase I made the last years, amazing sound but the best thing is its fantastic sound stage which goes incredibly deep. Orchestras are big as they should be (the Pacific didn't make this).
Thanks Nelson!
Hi Gary,
Found a Fet Ten/e phonostage, for a fair price.
I was satisfied with the one I had (a Boozhound Lab based on the French design of l'Audiophile by Mr. Walter, Le Pacific), but the Threshold beats it easily.
It is right now 100% original, but I will make some mods, starting with the power supply, probably in a larger case with a quite bigger tranny, more capacity (I have plenty of Mundorf 6800uF) and of course fast recovery diodes.
Next step would the stage itself. Beside the mods you made (tantalum, electrolytes), I'll replace the 10uF coupling caps, which Nelson liked to use in other electronics (I have a Threshold Fet One series II preamp, which had the same).
I've got excellent results with the Mundorf EVO Silver.Gold.Oil.
By analysing the schematic that you attached in the beginning of your thread I realised that the balanced output isn't a real balanced one... pin 3 is connected to the ground via a 10uF and two 220 ohms resistors. Guess I don't to replace this 10uF which is the same polyester type than the one where the signal goes through (C113).
But it's curious design: two EQ networks in parallel, then summed through R108 and R116, then through a single coupling cap.
This "balanced" output: what benefit would it have. I'm not using it, because my preamp doesn't have a balanced input, just curious.
Another curious thing was that I set the four gain switches to MC... and had very little gain with my low output cartridge, when switched to MM the gain was there?!?
Anyway, if you have a couple of minutes to comment on my comments, it would be nice. Via PM as well if you wish.
Best purchase I made the last years, amazing sound but the best thing is its fantastic sound stage which goes incredibly deep. Orchestras are big as they should be (the Pacific didn't make this).
Thanks Nelson!
One doesn't see too many of these on the used market, so congratulations on finding one.
I haven't experimented with the output caps in this unit but I did play around with them in an FET ten/hl line stage. I got results that I liked bypassing the existing 10uf caps with a 1uf polypro cap and .1uf paper in oil cap. Everyone has an opinion on the best sounding caps, so I'd suggest doing some experiments if you've got the patience. I also found that the orientation of the caps mattered, with one orientation being lower noise. I used clip leads for my experiments, making it easy to do quick comparisons.
Nelson should probably answer but I could imagine two benefits. First by providing an AC ground to the negative balanced input, it lets one use balanced cables which will avoid any chance for ground loops. Second, I'm sure that it had marketing benefit with some thinking that balanced designs are inherently superior.
Am I anywhere near correct in thinking this would work as a solution for a power supply for these units? I don't have a FET Ten but I do have a Forte 40 which used a very similar factory power supply. Sadly my 40 does not have a power supply at all and has sat silent for too long!
Universal Power Supply – diyAudio Store
In particular, using this board to build a PSU that would otherwise be intended for an Aleph J, F4, F5, F6, as stated here on their Aleph J page:
"PSU REQUIREMENTS
A Bipolar power supply of (+/- 24V) is required. This will require an 18V+18V (or 36V Center Tapped) transformer from 300-500VA, and PSU capacitance of 60,000uF per rail or more. A PSU for the F4, F5, or similar will be appropriate."
Can anyone confirm if I'm going down a decent path here?
Universal Power Supply – diyAudio Store
In particular, using this board to build a PSU that would otherwise be intended for an Aleph J, F4, F5, F6, as stated here on their Aleph J page:
"PSU REQUIREMENTS
A Bipolar power supply of (+/- 24V) is required. This will require an 18V+18V (or 36V Center Tapped) transformer from 300-500VA, and PSU capacitance of 60,000uF per rail or more. A PSU for the F4, F5, or similar will be appropriate."
Can anyone confirm if I'm going down a decent path here?
care to post some pictures, so we can see what's exactly in question?
ggl for "Forte 40" is giving me bunch of medical info, but none about your gadget
universal power supply is intended for power amps, but I'm somehow having impression that you're asking about preamp
so - that pcb is overkill for your needs, and we will find something more adequate
ggl for "Forte 40" is giving me bunch of medical info, but none about your gadget
universal power supply is intended for power amps, but I'm somehow having impression that you're asking about preamp
so - that pcb is overkill for your needs, and we will find something more adequate