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Old 4th October 2006, 07:14 AM   #101
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Hi Cheff
Quote:
Originally posted by CheffDeGaar
Thanks Rob

Do you have a schematic of the supply for your pre ?



I still wonder at what point of the circuit the input emotion is leaking,
cancelled or created...
It's the firs time I did a review about sound and maybe the last time because its very difficult to describe what you hear.
Build the amp and you hear what I mean.
I'm not bashing your amp and always looking for some improvement because building something is a part from the hobby.

Rob
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Old 4th October 2006, 07:48 AM   #102
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Very interesting listening tests
and good work from you who have designed and built the UGS module! Hats off.

Now,
to get the most out of the UGS module I think that some issues have not been dealt with.

I am thinking about the PS and the passive component quality.
IMHO - the UGS module is worth the best passive components one can afford and the best internal wiring and connectors and so on.

Dynamcs can be related to the capacitors used in the PS. Resolution has not been mentioned but resistors show different degrees of resolution.

Just to use standard metal film resistors and a simple PS is not going to give the best performance from the UGS module.

Dual mono setup is of course mandatory as are good transformers and excellent rectifying diodes. and active ground.

A regulated PS like this


Click the image to open in full size.

or like this

Click the image to open in full size.
is what I would use per channel.

And a setup like this for the transformers and AC mains filter

Click the image to open in full size.

or like this
Click the image to open in full size.

using this rectifying scheme (big caps not shown):

Click the image to open in full size.



Just my 2 cents.



Sigurd
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Old 4th October 2006, 08:36 AM   #103
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by Rob Dingen
Hi Cheff

It's the firs time I did a review about sound and maybe the last time because its very difficult to describe what you hear.
Build the amp and you hear what I mean.
I'm not bashing your amp and always looking for some improvement because building something is a part from the hobby.

Rob
I have impression that nobody criticize you,especially not your fast work;
and especially not me-just because you use tube preamp VS UGS one;
besides-I don't agree that tubes and 3 legged fuses are apples and oranges;
good gadget is good,doesn't matter with what is constructed;

what I say,and most of others replies on your test is that you didn't probably used best setup for UGS....you can freely disregard comparison with tube preamp......

develop tube preamp further
do the same with UGS
I'm sure that you have more than one room-to fill with music producing devices

and ,please,keep telling us your impressions
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Old 4th October 2006, 04:12 PM   #104
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Hi

Today I changed the feedback resistors from 56k to 150k so that I have a gain of 10x.
Also the 1k resistor to ground is now 10k.
The problems I have now is that itís not so stable anymore and offset is wandering around.
Also with the higher gain I get overshoot and I compensate it with a 10pf cap over the 150k feedback resistor and limited the bandwidth to 100Khz.
I think it sound better now with more dynamics and itís more musical.
Maybe Cheff has some more spare boards so that he can switch between the 2 and tell his listening impressions.
I donít now what causes the difference in the sound but I think the feedback resistors.
When I have time I change the 10k to ground to 4k7 or 2k2.
And maybe later change the Jfets to types with lower input capacitane.

Rob
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Old 4th October 2006, 04:14 PM   #105
Phill is offline Phill  France
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Sigurd Ruschkow,

I like much the cases of your electronic!
a little relativity in this world of perfection



Phill
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Old 4th October 2006, 04:28 PM   #106
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Hi Rob
Quote:
Originally posted by Rob Dingen
Hi Cheff

It's the firs time I did a review about sound and maybe the last time because its very difficult to describe what you hear.
Build the amp and you hear what I mean.
I'm not bashing your amp and always looking for some improvement because building something is a part from the hobby.

Rob
No problemo. I wasn't thinking your were bashing the pre, but rather
feeling that you were honestly reporting what you felt.
And you happen to prefer your tube pre, that's life

Anyone should thank you for a) building it so quickly, b) performing the tests,
and c) reporting . So many threads suddenly stop when it comes to
reporting listening results...

And I perfectly understand that it could be difficult to describe what
you're hearing. And the same goes for me, except it was just the
opposite global sensations I think nobody's wrong or right here,
it's just a matter of taste... Can we explain why some people only
swear by tubes, or class D and so on ? Surely no

I just hope it won't stop anybody to try this pre, experiment and report,
would it be good or bad...That's what this forum is for, and where
the fun is.

As far as I know, there's been only 3 ugs built using this schematic
and listened to. Too few to get a global picture, so we're waiting for
you, gentlemen. And the first ones I built were not top notch (single
supply, unshielded everywhere, etc...) but I already felt something
unusual

So I'll stick to ugs... until I build your pre

Cheers
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Old 4th October 2006, 04:36 PM   #107
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Rob,

Sorry, I was writing while you posted

Thanks for experimenting, and for this report.

I don't think you need to have a 10K Rout. Just leave it 1K, and keep
the 150K FB resistor. These 10K do not help stabilizing the offset (x10)
and the CL gain won't be much affected if you go back to 1K.

I've no spare boards with current mirrors, but I'll have soon, so I'll compare.

Just tell us how it goes, but thanks again for keeping it up.
I guess it's still less musical than tubes, but how does it improved ?

Regards
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Old 4th October 2006, 04:55 PM   #108
Buhl is offline Buhl  Denmark
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I have followed this thread with great interest - and desire to build a UGS - But I have a problem I think I share with a lot of people around the world - and that is the availability of the double Jfets 109/389 - I have found the 389 in UK @ 5 GBP a piece !! - thats something like 10 USD.....and then they are not in stock...

I think that if anyone who live in a part of the world where these part are easily available would like to start up a "helpline" supplying these small devices, many more UGS would be build.

So - if anyone knows any good, reliable places to buy them - please do tell me

Cheers !
Buhl
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Old 4th October 2006, 05:36 PM   #109
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Buhl -
I ordered some SK389V and SJ109V from Borbely Audio last week, and he still have some - in stock.
Price is good and service excellent

http://www.borbelyaudio.com/pics/Compprice.pdf




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Old 4th October 2006, 05:57 PM   #110
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Default 2SK389/2SJ109

I got mine here in the US from Dan Gardner (dan@djgardner.com), whom I hope doesn't mind my listing him here. They weren't too cheap (~$5-$6 US). I don't know if he has any more available for sale, but I sure appreciate his sale to me.
-willus
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