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Old 3rd October 2006, 05:25 PM   #91
philbyx is offline philbyx  France
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Quote:
Originally posted by Zen Mod



in case that you have unbalanced input to ugs ,then entire virtues of susy weren't present

I don't agree

Suzy effect is present if output is balanced, no matter about input : the thd born in the preamp is nulled between out+ and out-.

Philippe
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Old 3rd October 2006, 05:50 PM   #92
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Hi

I don't have a balanced source sorry.

Cheff I don't hate it and nothing is missing.
But there is better out there.
You hear inmediatly the difference.
And like transistors net every tube amp is good.
The only reason to build this preamp and other things is to improve my system.
The gain from my tube pre 10x and bandtwidht the same as the UGS 750Khz.
So the bandwidht is not the problem but maybe the input capacitane from the Jfets I don't no.
But maybe we can get it better.
Build my preamp and compare it to yours to find out.

Rob
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Old 3rd October 2006, 06:18 PM   #93
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Hi Rob,

Do you have a schematic of your tube pre ? And I know music is not
numbers (although Bach could be the exception ), but could you post
the same measurements results on your pre than you did on
the UGS (distortion, output Z, etc...) ?
Just to compare, not to compete

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Old 3rd October 2006, 07:35 PM   #94
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Hi Cheff

Ok I measure everything with 2V RMS.
Bandwidht 650Khz.
Gain Unbal in Unbal out 5x.
Gain Unball in Bal out 10x.
output imp 80 Ohm (but when the amplitude increase the output imp increase).
THD 0.02% one side not balanced and only 2e harmonics.
If you can make time and want to spend some money on parts build the tube preamp I think you would like it.
And no music are not numbers but emotion and one amp has it and the other not

Rob
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Old 3rd October 2006, 10:13 PM   #95
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Thanks Rob

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

Quote:
And no music are not numbers but emotion and one amp has it and the other not
I still wonder at what point of the circuit the input emotion is leaking,
cancelled or created...
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Old 3rd October 2006, 10:14 PM   #96
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by philbyx


I don't agree

Suzy effect is present if output is balanced, no matter about input : the thd born in the preamp is nulled between out+ and out-.

Philippe

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Old 4th October 2006, 03:41 AM   #97
spencer is offline spencer  Hong Kong
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Very interesting!

I shall report my listening test soon but it will be Oct 8 as I am too busy these few days.

I only feel 50k volume is a bit high for the UGS.

Rob, I shall also build your pre-amp for comparison in my my system. Thanks for sharing the design and it look like a NP Aleph P plus a source follower. Yes we need your power supply schematic also.

Valve amp is tasteful and what output cap you use? Do you use any expensive resistor also?

Cheers,
Spencer
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Old 4th October 2006, 04:45 AM   #98
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Rob, what kind of power supply design are you using for your UGS module? – what your pic shows seems a bit emaciated. Cheff was using isolated dual-mono power supplies with nice regulation and capacitance, and yours looks more like a linear regulator with input from a shared small, laminated core transformer. Your tub pre looked to have a more developed supply. Not that this is everything (I don’t know), but it could explain the lack of dynamics or, at least, separation. Can you post the supply schematic for your tub design to help in the compare? And what transformer are you using? Oh, and what make of tubes do you use?

I think THD should be lower for the UGS if the volume attenuation is at its input, while it may be more susceptible to noise before the JFET input. I noted Cheff had his attenuation at the output, a minor difference.

Quote:
Gain Unbal in Unbal out 5x.
Gain Unball in Bal out 10x
Did you short the negative output to GND for the unbal out case?

While any comparison is fair, and desired, I wonder if comparing a tub pre to solid-state is a bit like comparing apples to pears – or some other crunchy fruit. I’d be interested in a comparison of the UGS with other “top-class” solid state amps. Were the highs lacking in clarity and “seamlessness” on the tub pre as compared to UGS?
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Old 4th October 2006, 06:43 AM   #99
philbyx is offline philbyx  France
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Quote:
Originally posted by Zen Mod



Hello Zen Mod

I read again this post from Henrik this morning, about X on a bosoz, and...I was wrong... He explains how X works on a Bosoz, and the conclusion is : "XSOZ should not be driven unbalanced!".

http://www.diyaudio.com/forums/showt...410#post107410

Sorry

Philippe
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Old 4th October 2006, 07:02 AM   #100
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Hi

I attach the schematics of the power supply but there is one modification.
Between the 7806 GND pin and GND is a diode the Bat43.

It’s possible that the 50k pot is the problem indeed.
I’m building a 7 bit ladder volume at the moment and the print boards are ordered so I have to wait.
I build the same power supply as Cheff with maybe a small difference in capacitane see the picture on the previous pages.
I did short the negative input to ground.
Don’t think this comparison is apples to pears they both are a part of a music system and I don’t care what’s inside of it.
If you read my story before the Theta Casablanca with SixShooter sounded better on a couple of things as the Tube Preamp and it sounds better than the UGS module for sure.
But like the UGS and the Tube Pre are both in their development stage and for both can made changes that maybe bring some improvement to the sound.
Like I said lower feedback and increase output resistor to ground and for the Tube I want to make a current source for the followers.
The Tubes I used are Philips and the Caps at the moment from Audin Cap.

Rob
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