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Old 27th October 2010, 08:24 PM   #51
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Just want to correct error. After reading the tech notes, this mod reduces gain by 6 db from +24 to +18.

Now to the soldering iron

Maybe I have a bit of DIY gene after all. The Audio Note kits look quite interesting.
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Old 27th October 2010, 08:30 PM   #52
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Quote:
Originally Posted by GeneJazz View Post
.... The Audio Note kits look quite interesting.



correct thinking ....
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Old 28th October 2010, 07:28 PM   #53
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Just want to correct error. After reading the tech notes, this mod reduces gain by 6 db from +24 to +18.

Now to the soldering iron

Let me guess: this involves raising R9 from 1.5k to above 4k or thereabouts, right? It seems the only place you can reduce gain and not make S/N worse.

Unless it involves reducing the 15.4k resistors Basically it's either attenuating the output or increasing the NFB. If i were doing it it would take a lot of auditions to decide which is the lesser evil.

Last edited by analog_sa; 28th October 2010 at 07:37 PM.
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Old 28th October 2010, 07:39 PM   #54
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I understood that gain lowering is for amp?
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Old 28th October 2010, 09:43 PM   #55
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Originally Posted by analog_sa View Post
Let me guess: this involves raising R9 from 1.5k to above 4k or thereabouts, right? It seems the only place you can reduce gain and not make S/N worse.

Unless it involves reducing the 15.4k resistors Basically it's either attenuating the output or increasing the NFB. If i were doing it it would take a lot of auditions to decide which is the lesser evil.
The mod from ARC is to take out R9. First of all, their tech note states 1.82k resistor. It's 1.5k and this did nothing for the noise.
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Old 28th October 2010, 09:45 PM   #56
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I understood that gain lowering is for amp?
For the LS25 mk II preamp. The mod reduced the gain but the noise was just the same.

I suppose if I lower the gain on the VS60 power amp, it'll lower noise. I think I will accept that the SE output on LS25 is just not that great.
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Old 28th October 2010, 09:59 PM   #57
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Quote:
Originally Posted by GeneJazz View Post
For the LS25 mk II preamp. The mod reduced the gain but the noise was just the same.

....
completely logical ;


Quote:
Originally Posted by GeneJazz View Post
...

I suppose if I lower the gain on the VS60 power amp, it'll lower noise. I think I will accept that the SE output on LS25 is just not that great.
that will lower noise , and that is a way how I understood you in first place , just because gain lowering in preamp doesn't have anything with noise in amplification chain

ask that tech how to lower gain of amp itself

or give us schmtc and we will tell you
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Old 28th October 2010, 10:07 PM   #58
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I am considering balanced to unbalanced transformer converter. The thing is the ones you can buy might work in a recording studio for instruments but I believe it will detract from the sound in a Hifi system. Do you know of a good hifi balanced to unbalanced transformer converter? The balanced out on the LS25 is very quiet.

I don't have a schematic for VS60. I'll have to get one.
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Old 28th October 2010, 10:45 PM   #59
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even if I really like xformers in my audio chain ( now I'm running ancient repeater coils 600:1200 , connected as 1+4 autoformers ; it's between heavily changed Pioneer PD8500CD player (I/V xformer +buffer) and Papa's Koan F4 ; no volume between ) .......

anyway - even if I really like them - I'm using them in place of something , not as cure for something

are your sources balanced , so you have benefits from running balanced up to preamp output ?

edit :

give us few high res pics of VS from inside , and maybe we can figure out something regarding gain
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Last edited by Zen Mod; 28th October 2010 at 10:47 PM.
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Old 28th October 2010, 11:26 PM   #60
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even if I really like xformers in my audio chain ( now I'm running ancient repeater coils 600:1200 , connected as 1+4 autoformers ; it's between heavily changed Pioneer PD8500CD player (I/V xformer +buffer) and Papa's Koan F4 ; no volume between ) .......

anyway - even if I really like them - I'm using them in place of something , not as cure for something

are your sources balanced , so you have benefits from running balanced up to preamp output ?

edit :

give us few high res pics of VS from inside , and maybe we can figure out something regarding gain
My Cd player is balanced. The others are SE.

I've nixed out any mod to the VS60. It will void the warranty and I have a feeling, I will sell the amp sooner or later.

Looking into Lundahl transformers for now.
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