How to deal with a line preamp with too much voltage gain.

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ginetto61

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Hi !  i am posting here but feel free to move my lamentation where it belongs. 
I have had always issues with voltage gain in line preamps ... it is often too much.  Even like 6 times. 
With the result that even a small rotation of the volume zero provides already a quite loud sound.
Is there a way to attenuate the incoming signal before the preamp with some sort of resistors network/divider ?
assuming that my preamp has a low 10k input impedance which values are the best ?  an attenuation of 2-3 times should be enough. 
Or would it be better to put the same attenuator after the preamp ?  i am very confused. 
I love those preamps who come with a selectable voltage gain. 
Thanks a lot, gino

FredT300B

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I've used a Harrison Labs attenuator between the preamp and the amp. https://www.hlabs.com/products/attenuators/

ginetto61

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I've used a Harrison Labs attenuator between the preamp and the amp. https://www.hlabs.com/products/attenuators/
Hi ! thank you very much indeed for your valuable advice.  And are you happy with the sonic result ?  are there requirements for the pre out impedance or the power amp input impedance ? 
I looked at the product page but i have not understood very well
Thanks again, gino

Speedskater

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Re: How to deal with a line preamp with too much voltage gain.
« Reply #3 on: 13 Jul 2020, 12:56 pm »
Harrison Labs products at PartsXpress:
https://www.parts-express.com/brand/harrison-labs/265

There are no special impedance requirements when used with solid-state pres and amplifiers.

ginetto61

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Re: How to deal with a line preamp with too much voltage gain.
« Reply #4 on: 13 Jul 2020, 01:06 pm »
Harrison Labs products at PartsXpress:
https://www.parts-express.com/brand/harrison-labs/265 
There are no special impedance requirements when used with solid-state pres and amplifiers. 

Hi ! thanks a lot for the very helpful advice.  I asked because i read something about impedance matching issues in passive preamps that can have indeed a great potential for clean sound but only if the impedance is kept low.  Most of them have input impedances around 10kohm. 
Quote
https://www.stereophile.com/content/placette-audio-remote-volume-control-passive-preamplifier-specifications

Elizabeth

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Re: How to deal with a line preamp with too much voltage gain.
« Reply #5 on: 13 Jul 2020, 01:47 pm »
total heresy and I have been thoroughly insulted hated and put down for it but I use two preamps. the very first time the hatred was like a tsunami of vile responses. Since then I have come to regard two preamps as my signature (with a big kiss my === to the haters,) . if you cant get past the use of two devices together, then you clearly live in specs and theory, and not actually listening.. is my take on it.
Anyway yes i use two preamps. I own a pile of them, and use two together at all times.
Usually the Byrston BP-26 and a Threshold FET TEN' or the BP-26 and a ARC Sp-15 or the BP26 and a VAC Standard,or the BP26 and an Audible Illusionsorthe BP-26 and a Conrad Johnson Act 2
It solves the too much gain with two vol controls. and sounds great.

Stercom

Re: How to deal with a line preamp with too much voltage gain.
« Reply #6 on: 13 Jul 2020, 02:23 pm »
I've used this in the past with good results.  http://www.rothwellaudioproducts.co.uk/html/attenuators.html

ginetto61

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Re: How to deal with a line preamp with too much voltage gain.
« Reply #7 on: 13 Jul 2020, 02:40 pm »
total heresy and I have been thoroughly insulted hated and put down for it but I use two preamps. the very first time the hatred was like a tsunami of vile responses. Since then I have come to regard two preamps as my signature (with a big kiss my === to the haters,) .
if you cant get past the use of two devices together, then you clearly live in specs and theory, and not actually listening.. is my take on it.
Anyway yes i use two preamps. I own a pile of them, and use two together at all times.   Usually the Byrston BP-26 and a Threshold FET TEN' or the BP-26 and a ARC Sp-15 or the BP26 and a VAC Standard,or the BP26 and an Audible Illusionsorthe BP-26 and a Conrad Johnson Act 2
It solves the too much gain with two vol controls.   and sounds great.   

Hi ! i have been insulted many times also myself ... often in my case for good reasons  :)
I think that all boils down to power amps input Sensitivity for Full Rated Output ... usually 2Volts.  It is too high.  Line preamps have absolutely no problems in putting out 10 and even 20Volts noise and distortion free.  An example here
https://www.stereophile.com/content/bryston-bp-173-line-preamplifier-measurements


the sweet spot is around 10V and that could be the input standard sensitivity for a power amp.  I have been told that would be better to place more of the gain of the chain in the unit with the lowest distortion and noise (so the preamp). 
Using an active preamp with a knob that cannot reach 12' o clock position is frustrating.   
However considering that solid state preamps, what i use, usually have no problems even with 600ohm load i would use a resistor based voltage divider with an input impedance of 1-2 kohm and so a very low Zout just at the power amp inputs.

Stercom

Re: How to deal with a line preamp with too much voltage gain.
« Reply #8 on: 13 Jul 2020, 03:14 pm »
You have too much voltage gain from your preamp. This is a common problem in pro and audiophile applications. Read the link I provided from Rothwell. I assume the Harrison Labs version that others told you about is fine too. Don't worry about impedance mismatches from passive preamps. My final 2 cents.....and I'm out of here!

Speedskater

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Re: How to deal with a line preamp with too much voltage gain.
« Reply #9 on: 13 Jul 2020, 10:06 pm »
A passive pre-amp is nothing more than an adjustable attenuator.
But if you need both, but the fixed attenuator near the amplifier input.

mick wolfe

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Re: How to deal with a line preamp with too much voltage gain.
« Reply #10 on: 13 Jul 2020, 10:53 pm »
total heresy and I have been thoroughly insulted hated and put down for it but I use two preamps. the very first time the hatred was like a tsunami of vile responses. Since then I have come to regard two preamps as my signature (with a big kiss my === to the haters,) . if you cant get past the use of two devices together, then you clearly live in specs and theory, and not actually listening.. is my take on it.
Anyway yes i use two preamps. I own a pile of them, and use two together at all times.
Usually the Byrston BP-26 and a Threshold FET TEN' or the BP-26 and a ARC Sp-15 or the BP26 and a VAC Standard,or the BP26 and an Audible Illusionsorthe BP-26 and a Conrad Johnson Act 2
It solves the too much gain with two vol controls. and sounds great.

I've done the same (2 line pre-amps back to back) with excellent results for years. Shindo Aurieges MM into a LM 218ia. Even had a friend tell me he was demoed an Aurieges/LM218ia combo in a back/back configuration. This at an uber pricy hi-end shop years ago. He too used this same set-up for a year or so. In this case the Aurieges's vol. control is set at roughly 11 o'clock and the final volume setting is done on the LM.

ginetto61

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Re: How to deal with a line preamp with too much voltage gain.
« Reply #11 on: 14 Jul 2020, 06:30 am »
You have too much voltage gain from your preamp. This is a common problem in pro and audiophile applications. Read the link I provided from Rothwell. I assume the Harrison Labs version that others told you about is fine too. Don't worry about impedance mismatches from passive preamps. My final 2 cents.....and I'm out of here!

A passive pre-amp is nothing more than an adjustable attenuator.  But if you need both, but the fixed attenuator near the amplifier input.

Hi ! thanks to all for the very valuable advice and i think i may have found a solution.  I have at hand a tube buffer with volume pot.  This one

https://www.amazon.it/FX-Audio-TUBE-01-Buffer-Amplifier/dp/B06XCT2ZGS


I could place it after the preamp and before the power amp and so reducing the voltage to the power amp.  Being a buffer it should not have particular issues to drive the power amp.  In this way i could use more of the gain of the preamps and have a better control of the volume. 
Moreover the tubes can add some warm to the sound that is often a good thing with digital sources. 
I am shocked by the difference a good preamp can do.  Often in the press reviews of decent commercial pre and power amp combinations (i am talking about solid state units only)  the preamp comes out as the worse of the two.  I remember in particular a review of a pre and power amp made by Rotel.  Replacing the Rotel pre with a tube one made the sound quite phenomenal.  How can this be i really do not understand.
Why tube preamps sound always at least very good and instead good solid state preamps are so rare ?   
Thanks a lot again. 
Have a nice day
gino   

P.S.  i have been advised to replace the stock tubes in the buffer.  I will be trying these soon ...
https://www.ebay.com/itm/112773986676