Too much gain

[Slawts]

This has been something that has been bugging me slightly for a while but became more apparent when my pre came back from repair. In its absence I have been using an Audiolab Q Dac as a pre with my XTC Pow1 power amp and it is absolutely quiet when on.

Putting back my VTL 2.5 pre there is audible hiss when no music is playing and it is not on mute.

I only use the volume control between 7 and 9 o'clock as that is at 9 it is extremely loud so am thinking the pre is too high gain.

I am looking for a cheap solution and have thought about trying some attentuators (Rothwell?) but am concerned it degrades the sound.

Would changing valves in the line section help? They are ecc82's feeding in to 6350's and I was thinking about trying a lower gain version of an ecc82 equivalent.

Steve

[Stryder5]

This has been something that has been bugging me slightly for a while but became more apparent when my pre came back from repair. In its absence I have been using an Audiolab Q Dac as a pre with my XTC Pow1 power amp and it is absolutely quiet when on.

Putting back my VTL 2.5 pre there is audible hiss when no music is playing and it is not on mute.

I only use the volume control between 7 and 9 o'clock as that is at 9 it is extremely loud so am thinking the pre is too high gain.

I am looking for a cheap solution and have thought about trying some attentuators (Rothwell?) but am concerned it degrades the sound.

Would changing valves in the line section help? They are ecc82's feeding in to 6350's and I was thinking about trying a lower gain version of an ecc82 equivalent.

Steve

I tried attenuators both home made and from various branded suppliers, and found degradation of sound. I only speak from my opinion on my system.

Did your VTL exhibit this hiss before repair, assuming it was working at that time.

What was the issue before repair, and what was done?

Gary

[Slawts]

I tried attenuators both home made and from various branded suppliers, and found degradation of sound. I only speak from my opinion on my system.

Did your VTL exhibit this hiss before repair, assuming it was working at that time.

What was the issue before repair, and what was done?

Gary

Yes always hiss with the XTC. I used a VTL ST85 power before and no issue but it couldn't drive my speakers the way the XTC does.

The repair was replace the selector switch and clean the balance and volume. Well worth it as it sounds better except for the hiss.

I have heard similar about the attentuators that's why I'm not so keen.

[Stryder5]

Yes always hiss with the XTC. I used a VTL ST85 power before and no issue but it couldn't drive my speakers the way the XTC does.

The repair was replace the selector switch and clean the balance and volume. Well worth it as it sounds boetter except for the hiss.

I have heard similar about the attentuators that's why I'm not so keen.

Just maybe one of those mismatches that appear occasionally.

Perhaps someone else will comment on their opinions?

I have some named attenuators that I can send to you to try, if they work we can come to some arrangement, if not send them back :)

Gary

[Firebottle]

20dB gain is rather high for a line preamp IMO.
It is unlikely to affect the gain with a valve substitute as the gain level is set via a feedback network.

Personally I would modify the circuit values to lower the gain.

[Slawts]

Just maybe one of those mismatches that appear occasionally.

Perhaps someone else will comment on their opinions?

I have some named attenuators that I can send to you to try, if they work we can come to some arrangement, if not send them back :)

Gary

Very kind. I will hold off at the moment. I tried swapping valves but the set I have in sound the best. The hiss isn't too bad so I'll live with it a while.

Alan are you sure it is as much as 20db gain? The new ones are adjustable but have 8/14db. You are right 20 does seem high.

[Mike Reed]

Don't know your kit, but f.w.i.w., I suffered far too much gain from my Lector CDP (circa 3.4V). When I had the Naim 552 it didn't bother too much, though compressed CDs sounded awful and vol. range was low (akin to yours). When I moved to E.A.R. valved pre with meters, it REALLY bugged me to see those needles hitting the stops on peaks.

I put a thread on another forum and got lots of advice re. the value of attenuators I required; all, as it transpired, wrong, but diagnosis from afar can be fraught. Science/ mathematics helps, but not, it seems, in this case. A friend lent me a -15 dB and -10 dB. The former showed too much attenuation and I thought it restricted s.q. a bit. The -10dB was better, but still a bit o.t.t.

I then took a punt and bought a Goldenjacks -6dB. Perfect ! No discernible deterioration in s.q. and they kept the needles and vol. control within tolerable range.

Attenuation is attenuation, so I hope the foregoing may have a bearing. Whereas there've been lots of negative comment about s.q. suffering from attenuation, my opinion is now that the less attenuation you have, the less s.q. interference. Logical, I s'pose, with hindsight. Below -10 dB, I think you'd be hard pressed to suffer, but try a low number first; say, -6 or -8dB.

[Slawts]

Hi Mike,

Goldenjacks seems to be no longer operating but I think I will look in to it.

There seems to be quite a debate about whether attentuators spoil the sound or not but I guess the only way to know is try it.

[Slawts]

Just maybe one of those mismatches that appear occasionally.

Perhaps someone else will comment on their opinions?

I have some named attenuators that I can send to you to try, if they work we can come to some arrangement, if not send them back :)

Gary

Gary is that offer still open and what db level are they?

[Edward]

I have a pair of RCA Goldenjacks and a pair of XLR Rothwells somewhere you can try and return. Each I think at 10db attenuation.

I'd need to find them if you are interested. :eyebrows:

[Stryder5]

Gary is that offer still open and what db level are they?

Yes offer still open 10dB

Just PM me your address.

Gary

[Slawts]

I have a pair of RCA Goldenjacks and a pair of XLR Rothwells somewhere you can try and return. Each I think at 10db attenuation.

I'd need to find them if you are interested. :eyebrows:

Hi Edward,

The rca Goldenjacks would be interesting but I don't have balanced sockets so the Rothwells are out. I think 10db is the max I would want to try. If you are in N2 I can pick up as I am just in W3 off the North Circular.

[Edward]

Cool. Yes I'm familiar with the North Circular (unfortunately). :)

Let me find them. I'll send you a PM. Gary may have a better quality pair so try both.

If 10db attenuation works for you I'd recommend you go with Alan's suggestion of changing the gain in the pre.

[Slawts]

Cool. Yes I'm familiar with the North Circular (unfortunately). :)

Let me find them. I'll send you a PM. Gary may have a better quality pair so try both.

If 10db attenuation works for you I'd recommend you go with Alan's suggestion of changing the gain in the pre.

Yes, I'm going to try Gary's as well. If either a success :eek:

If not, I'll be able to bore for Britain on the subject.

[Slawts]

I have had a chance to borrow a set of Rothwell and Golden Jacks and been trying them in my system between the pre and power and plugged in to the power end. Listening has been vinyl, CD and high res via a Fiio plugged in to an Audiolab Q Dac.

Firstly my extreme thanks to both Stryder5 and Edward of this parish for the loans and the latter for a listen to his magnificent Tannoys via two flavours of valve amplification.

The Rothwell and Golden Jacks are both 10db attenuation although the latter are a little louder and listening volume is now moved from around 8 o'clock to a little past 9. The Golden Jacks are larger and a bit blingy. The Rothwells are more refined looking and smaller but plugging the interconnect in to the female is more difficult as there is a lip around which stops my interconnect fully engaging. I would consider this a design fault.

I used a sound meter app on my phone to try and set levels but all figures should be judged as approximate.

Full rig switched on with the pre on mute gave a level of 24db with the phone next to the tweeter/mid dual concentric unit. Pre mute off without attenuators gave a reading of 29db and I could hear audible hiss standing next to the speaker.

Fitting either pair brought the level down to 24db and no hiss unless you put your ear right to the speaker. Even then it was very faint. Result.

Listening levels were between 60 and 80db.

Listening commenced with the Golden Jacks and I tried prolonged listening then swapped.

I noticed that they need to be in for a little while to warm up before they come on song. An example of this, having changed over to the Rothwells I put on Running on Empty by Jackson Browne. The first couple of tracks sounded ok but then the sound seemed to grow and Jackson was singing about Rosie there in my room. It was unreal and so transparent!

I swapped between them over the days and it was extremely difficult to judge one better over the other. I can only give a flavour to each. The Golden Jacks seemed slighty better in the bass but treble seemed slighty rolled off. The Rothwells at one stage seemed slightly less transparent and harsh and then more transparent with a touch more air. I can really only say with certainty if I owned the Golden Jacks I wouldn't change them and vice versa.

The improvements that both bring are a lower noise floor so darker background. There is a lack of hard edge and the music relaxes. Acoustic instruments sound more authentic. Dynamics are unchanged but transparency increased and I heard the occasional detail which I had never noticed before. This even happened on a vinyl copy of Something/Anything by Todd Rundgren which I bought new circa 1974 and have on 24/96 download as well. I thought I had heard everything on that album!

For me, a pair of attenuators is a must buy. As the volume control is only now around 9 I wonder if purchasing 15db or 20db will bring more benefits. There are only two other manufacturers I can find as alternatives, Russ Andrews at an eye watering £101 or Harrison Labs about £30+ but need to be ordered from the States. I would love to know if anyone has tried and compared these to the Rothwells or Golden Jacks.

I hope this useful to those with the same problem. It has stopped me wanting to buy a new pre (for now!!!) so that's a financial relief.

[Edward]

Interesting and glad the loan of the attentuators proved useful Steve.

As per our PMs I'm still confused if it is your pre giving out too much voltage or your power amp being too sensitive - or a bit of both?

I forget now, but did you try a different pre or power to see if you can track down where the issue is?

Perhaps Alan (Firebottle) can knock up some attenuators for you? Surely they are simply in line resistors? So male and female phono connectors, a bit of cable, resistors and heatsink I'd imagine?

[graham67]

Hi Steve, i had a similar problem with a Canary Audio Pre amp. I took it to Henry Durrant Toprepairman near Leatherhead so not too far from you. Henry made some simple modifications to the circuit to significantly reduce gain which worked perfectly, increasing usable volume range and reducing noise.

[graham67]

Btw, i agree with your assessment of the Rothwell and GoldenJack attenuators. I have had both and consider the Goldenjacks are more transparent and made a firmer connection at both ends.

[Slawts]

Interesting and glad the loan of the attentuators proved useful Steve.

As per our PMs I'm still confused if it is your pre giving out too much voltage or your power amp being too sensitive - or a bit of both?

I forget now, but did you try a different pre or power to see if you can track down where the issue is?

Perhaps Alan (Firebottle) can knock up some attenuators for you? Surely they are simply in line resistors? So male and female phono connectors, a bit of cable, resistors and heatsink I'd imagine?

Hi Edward,

I think it is the pre has too much gain.

I tried it with an Audiolab Q dac as a pre and it was absolutely silent.

I have bought the Rothwells so will keep with them in the system which is now happily quiet.

"Btw, i agree with your assessment of the Rothwell and GoldenJack attenuators. I have had both and consider the Goldenjacks are more transparent and made a firmer connection at both ends."

Hi Graham I actually thought the Rothwells were slightly more transparent although the Golden Jacks have the better connections. There's really not much between them. The Golden Jacks seem better value but the guy who makes them seems to have disappeared so I don't think they are made anymore. Shame.

[Mike Reed]

As you are using the attenuators before the power, you might be successful with -15dB ones, though I'm quite convinced that the greater the attenuation the more impairment to dynamics; stands to reason (i.m.o.). My G/jacks (-6dB) were used between CDP and pre. at the pre. end, as it was only the CDP which had too much gain. Nicely made, G/jacks. Maybe the R.A. ones use silver wire for that price ! :lol:

[Slawts]

As you are using the attenuators before the power, you might be successful with -15dB ones, though I'm quite convinced that the greater the attenuation the more impairment to dynamics; stands to reason (i.m.o.). My G/jacks (-6dB) were used between CDP and pre. at the pre. end, as it was only the CDP which had too much gain. Nicely made, G/jacks. Maybe the R.A. ones use silver wire for that price ! :lol:

Hi Mike,

Yes they are plugged in the the power which seems to be the recommended spot and they really have improved the sound.

I have been wondering whether greater attenuation might have a negative effect or not.

At the moment I'm in the if it ain't broke camp :)

[Edward]

At the moment I'm in the if it ain't broke camp :)

I find that feeling wears off after about 72 hours replaced with 'how can I improve things?' :lol:

By the way here is a snapshot (https://web.archive.org/web/20120210101256/http://www.goldenjacks.com/) of the old goldenjacks website. Interesting read.

[montesquieu]

I would be tempted to use attenuators to figure out the exact amount of attenuation I needed, and then have someone technical solder in a voltage divider (which is what the attenuators have, inside the plug), using really high quality resistors, hard wired to the input sockets of the power amp. You can always have them removed if you ever switch to a preamp with less (or no) gain.

[struth]

It's an odd thing, and technically shouldn't be but I've found external ones do kill dynamics a bit.
I free with Tom find what you need and get it fitted into circuit.

[walpurgis]

It's an odd thing, and technically shouldn't be but I've found external ones do kill dynamics a bit.

Me too.

[Slawts]

I would be tempted to use attenuators to figure out the exact amount of attenuation I needed, and then have someone technical solder in a voltage divider (which is what the attenuators have, inside the plug), using really high quality resistors, hard wired to the input sockets of the power amp. You can always have them removed if you ever switch to a preamp with less (or no) gain.

I am surprised it is the power amp as I would have thought lowering the output from the pre more logical. Or is it the same principal as used for where you put the attenuators?

It is a thought and maybe consider 15 or 20db.

[Slawts]

I find that feeling wears off after about 72 hours replaced with 'how can I improve things?' :lol:

By the way here is a snapshot (https://web.archive.org/web/20120210101256/http://www.goldenjacks.com/) of the old goldenjacks website. Interesting read.

Fascinating site and you may be right :stalks:

[anubisgrau]

I would be tempted to use attenuators to figure out the exact amount of attenuation I needed, and then have someone technical solder in a voltage divider (which is what the attenuators have, inside the plug), using really high quality resistors, hard wired to the input sockets of the power amp. You can always have them removed if you ever switch to a preamp with less (or no) gain.

probably the best advice here, except for a definitive solution - sell the current pre, analyze your system to find what gain you need, buy an appropriate new pre.

[Slawts]

I thought i would just revive this as it is now a month since I had the Rothwell attenuators in.

I have now forgotten about them but my albums and stereo are much happier.

I have a quiet soundfloor and the detail is much much better.

The only downside is I have put the Koetsu back in preference to the Ortofon Jubilee and it sounds spectacular.

I am trying not to develop a love of high end cartridges and especially Koetsus (that way penury) but it is proving difficult.

Be careful what you wish for.