Restoring a Threshold FET 10e - a few questions - Page 7 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th September 2013, 06:42 PM   #61
GaryB is offline GaryB  United States
diyAudio Member
 
Join Date: Sep 2002
Location: Silicon Valley
Quote:
Originally Posted by Etnier View Post
In case of interest to anyone: an image of my phono pre: arrived Friday
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
Attached Images
File Type: jpg etnier_fetphono_marked.jpg (552.2 KB, 227 views)
  Reply With Quote
Old 15th September 2013, 06:54 PM   #62
diyAudio Member
 
Join Date: May 2011
Thank you, Gary! I would have been replacing a lot more caps in there!
  Reply With Quote
Old 15th September 2013, 06:54 PM   #63
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
Talked to Wayne, he verified +/- 24v

18+18v transformer is great
  Reply With Quote
Old 15th September 2013, 07:01 PM   #64
diyAudio Member
 
Join Date: May 2011
Thanks very much, 6L.
  Reply With Quote
Old 15th September 2013, 07:36 PM   #65
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Quote:
Originally Posted by 6L6 View Post
Talked to Wayne, he verified +/- 24v

18+18v transformer is great
it is , if 24Vdc is voltage needed before regs
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 15th September 2013, 10:22 PM   #66
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
Quote:
Originally Posted by Zen Mod View Post
it is , if 24Vdc is voltage needed before regs
Yes.
  Reply With Quote
Old 21st January 2015, 06:44 PM   #67
diyAudio Member
 
Join Date: Jan 2004
Location: GRASSE (France)
Quote:
Nounours,
I look forward to your experiments in this regard. Your experience upgrading your 10e seems to match mine, so I'd be very interested the results if you have time to experiment with battery supplies.

By the way, I think it's time for me to replace the volume/balance control in my 10e. I thought the preamp was sounding good but I did a quick experiment that tells me there is still a lot of room for improvement. I swapped out the 10e for a passive preamp using optocouplers. It's based on the Warpspeed modules that Blues mentioned in post #3. While I still think that an active preamp has a drive that passive preamps miss, there is no question that the optocoupler passive preamp had much greater transparency and detail. So I'm going to try putting better volume controls in the Threshold. And I'll add a buffer to the Warpspeed - perhaps that will give the best of both worlds.

---Gary
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
  Reply With Quote
Old 2nd February 2015, 11:44 PM   #68
GaryB is offline GaryB  United States
diyAudio Member
 
Join Date: Sep 2002
Location: Silicon Valley
Quote:
Originally Posted by Nounours18200 View Post
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 . . . built around one hundred Nichicon Muse KZ capacitors instead of 2 big Nichicon Fine Gold.

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 . . .

The common point between these 2 upgraded Fet-10He is that they sound very very similar.

. . . I have experimented in all my recent upgrades that the Teflon insulated cables provide better results over PVC insulated cable (the core of the cable being of course exactly the same) in the power supplies (not talking about the signal 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
  Reply With Quote
Old 3rd February 2015, 12:54 AM   #69
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
no need to go in Gargantua size direction with xformer

if one is already willing to try old ways , better to invest in choke input primary filter
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 18th March 2015, 07:49 PM   #70
diyAudio Member
 
Join Date: Jan 2004
Location: GRASSE (France)
Hi Gary,

Quote:
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 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.

Quote:
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?
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 by Nounours18200; 18th March 2015 at 07:53 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Restoring a Threshold SL10 GaryB Pass Labs 6 13th March 2013 10:18 AM
Fuse replacement for Threshold SA/10e turbogti Pass Labs 2 15th June 2011 03:40 AM
Threshold FET 10e Manual hifi-hospital Solid State 3 12th April 2009 03:24 PM
Threshold FET 10/pc Phono Stage Preamp Schematics aka FET 10pc, FET-10pc, fet ten/pc krellkraver Solid State 1 8th February 2007 03:05 PM
threshold fet-9 coffin Solid State 0 17th March 2004 05:51 AM


New To Site? Need Help?

All times are GMT. The time now is 02:06 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2