[jaspal kallar]

Hi

My Altmann Dac and amp combination results in too much gain (my speaker are Kef 103/4, 91 db efficiency). By too much gain I mean at lowish volumes the sound is already too loud.

Charles Altmann suggested that:

"For reducing the gain, you have to insert 2x 25kOhm resistors into your RCA connection cables (one per channel).
The resistors are inserted into the hot wire inside the RCA plug (amplifier side)."

OK I'm no DIY cable person so I was wondering if this is something that a competent hifi repair person can do (quite easily and hopefully cheaply)?

    jaspal

PS. I tried Rothwells in-line attenuators and I didn't like them (at all!).

[BobM]

The correct way to do this is by using a voltage divider network. That's 2 resistors, not one. The second one is shunted to ground. Here's a link to more info and a calculator to help you decide which resistor values you should use. Since these are directly in the signal path you should also use good quality resistors.

http://www.raltron.com/cust/tools/voltage_divider.asp

Enjoy,
Bob

[Steve Eddy]

Altmann's website says that he offers the BYOB in both high gain (standard) and low gain versions. Which one is yours? If it's the high gain version, the preferable solution would be to go with the low gain version.

se

[jaspal kallar]

Altmann's website says that he offers the BYOB in both high gain (standard) and low gain versions. Which one is yours? If it's the high gain version, the preferable solution would be to go with the low gain version.

se

Hello,

Mine is high gain (bought it  used) but I want to able experiment trying different speakers (for now). Later when I've decided on a speaker can like you say, get can the appropriate version.

Thanks,
     jaspal.

[G.Michael]

Jaspal,

A few years ago I had a conrad-johnson preamp that had too much gain for my setup.  I went about putting voltage dividers at the preamp inputs, with good success. 

As I recall, the input impedance of the preamp was 50k, and I went about choosing the resistor values so that the input impedance with the resistors installed would still be 50k.  It involves using some old-fashioned high school algebra.  Basically, you choose the two resistor values to satisfy two specifications:  1.  desired attenuation, like 0.5 for a 6dB voltage attenuation    2. input impedance with resistors installed, e.g., 50k.  So, all this leads to two equations and two unknowns (the resistor values), and then the solution is the formulas for the resistor values.  The actual calculations, at that point, are no big deal.  (I think I still have my notes.)

ALL THAT SAID... there's a good chance that Mr. Altmann took into account the input impedance of your amplifier and the output impedance of your DAC when he suggested the single 25k resistor.  The resistor + input impedance effectively forms a voltage divider that creates the attenuation.  Not a big deal for a technician to solder a resistor into an interconnect cable.  Make sure that you use very high quality resistors, and good solder, too.  You may need to provide those things if the tech isn't familiar with the audiophile stuff.

Gary

[tanchiro58]

Altmann's website says that he offers the BYOB in both high gain (standard) and low gain versions. Which one is yours? If it's the high gain version, the preferable solution would be to go with the low gain version.

se

Hello,

Mine is high gain (bought it  used) but I want to able experiment trying different speakers (for now). Later when I've decided on a speaker can like you say, get can the appropriate version.

Thanks,
     jaspal.

Jaspal and Steve,

My BYOB amp had high gain to and I just replaced the stock volume pod(10K) with a Goldpoint 100K stepped attenuator. Now I am able to crank up the volume to 12 o'clock without the irritation of loudness (high pitch). The solution of changing speakers does not sound good to me since you have to spend more money. The stepped attenuator costs only $150-$200. However, that is your choice. Good luck.



Tan

[jaspal kallar]

Jaspal,
ALL THAT SAID... there's a good chance that Mr. Altmann took into account the input impedance of your amplifier and the output impedance of your DAC when he suggested the single 25k resistor.  The resistor + input impedance effectively forms a voltage divider that creates the attenuation.  Not a big deal for a technician to solder a resistor into an interconnect cable.  Make sure that you use very high quality resistors, and good solder, too.  You may need to provide those things if the tech isn't familiar with the audiophile stuff.

Gary

Cheers Gary.  Yes that is one of my concerns about the quality of the resisters (I had not thought about the solder ... good point). However, I wouldn't know a good resister if it reared up and bit me on the nose    Then what kind of resister should I use; carbon or metal film - I've no idea.


Gary, if I'm not mistaken doesn't Charles Altmann mean 2x25k per RCA plug? That's what he confirmed to me today.

Another suggested solution to me was of having a quality step attenuator (dact or similar) between the Dac and the amp. Charles said this solution was also good alternative. Of course it's more expensive.

 
I've contacted Paul Speltz about buying one of his anti-cables and said he could insert the resisters but I've not asked him about quality (yet).

 

My BYOB amp had high gain to and I just replaced the stock volume pod(10K) with a Goldpoint 100K stepped attenuator. Now I am able to crank up the volume to 12 o'clock without the irritation of loudness (high pitch). The solution of changing speakers does not sound good to me since you have to spend more money. The stepped attenuator costs only $150-$200. However, that is your choice. Good luck.

Tan, nice work!  Pity I've no DIY skills. So changing the volume pot is a non starter for me.  Btw. I'm not thinking of changing to new speakers to solve this problem.  What wanted to say is that I perhaps one day I would like to try others speakers but I would like to keep the high gain version of the BYOB I have now. So Charles solution and the step attenuator between the Dac & Amp would allow this.

So far, here in Stockholm (Sweden) the hifi repair/cable people who could do the resister insertion work have declined. They said that perhaps there would not be enough space. Others doubted the suggested resister values. So I have to look elsewhere.  That's why I posted this thread to see if it is possible. 

Thanks for the answers so far!

   jaspal

[G.Michael]

Jaspal,

I'm thinkin' that Paul Speltz will have no trouble doing this.  If you need to provide Paul with resistors, PM me.  A buddy of mine probably has good resistors in the 25k range.  (I'd refer you to Michael Percy Audio, but I believe that Michael requires a $25 minimum order.)

So, for each cable: One 25k resistor would go inline on the + wire.  The other 25k resistor would go between the + and - wires.

Gary

[Bemopti123]

had the same problem with an overtly high gain preamp....While people were telling me what I needed to do, I went the easy route and plunge some money on a pair of naked EVS attenuators.  They solved my problem outright and, I have the choice of changing master attenuation to different settings on the flight.  Definitely not cheap, but excellent results without all the fuzz.

[SET Man]

Hey!

   I also have this problem and still do!

   I put a pair 100K step ladder type attenuator in my pre and the steps is too coarse... especially with my TT. 

   I did solved the problem by making a -10dB pre-attenuation before the attenuators according to Goldpoint... 



http://www.goldpt.com/mods.html



  I took the picture above shows the Vishay "nude" S102 and Caddock TF020.

  Even with that it ain't over. The reason is that every resistors I put in, I could hear the change. I've gone through couple of resistors already including some good one like...

  Caddock MK132 and TF020. I do hear some roll off top from these. Currently I have Vishay nude S102 this doesn't seem to rolled off much very close to without resistor. But! it seems to take away the roundness and make things sound cooler and thinner in the mid. Still not good. 

   I still have this problem and it could be annoying especially with LP playback. All the resistor I've tried so far have some downside and I can't seem to get over it! 

  So, I guess I have to put up with this. With some LPs I have to either listen to lower level than I would want to or louder than I would want too Well, I have to see if I there is another way to fix this. 

Take care,
Buddy

   

[tanchiro58]

SETman,

I did really replace the stock 10K volume pod in my BYOB amp with a goldpoint 100k stepped attenuator and it comes out an excellent result. The BYOB amp sounds more lively from the position of 9 o'clock to 2 o'clock like Goldpoint suggested.

Tan

[SET Man]

SETman,

I did really replace the stock 10K volume pod in my BYOB amp with a goldpoint 100k stepped attenuator and it comes out an excellent result. The BYOB amp sounds more lively from the position of 9 o'clock to 2 o'clock like Goldpoint suggested.

Tan

Hey!

    Well, it ain't going to easy for me. My pre of which is Audio Note M1 Phono came with 100K Noble pot. Back than I didn't have this problem with my previous speaker with much less sensitivity than what I have now (85dB vs 94dB) So, when I replaced the Noble I went with a pair of 100K Ladder step attenuator kit from Welborne Lab with Gray Hill switches and Holco resistors (older one without magnetic cap) It was fun building them... just kidding, not really

    If I only knew that I will be using speaker with 94dB I would have gone with the 250K kit.

   Anyway, maybe I need to rebuilt it to make it 250K. But that's mean buying a new set of resistors. It will harder to rebuilt them because I have to de-soldering and remove those resistors and put in new ones. Hmmm... maybe I could just build a new pair of 250K attenuators than. 

Take care,
Buddy

[jaspal kallar]

had the same problem with an overtly high gain preamp....While people were telling me what I needed to do, I went the easy route and plunge some money on a pair of naked EVS attenuators.  They solved my problem outright and, I have the choice of changing master attenuation to different settings on the flight.  Definitely not cheap, but excellent results without all the fuzz.

Hi Bemopti123,

I did think about this but instead with the Scott Endler attenuators (http://mysite.verizon.net/vze4c5pt/id2.html) but I wasn't sure they would fit easily on the already cramped BYOB amp.  I don't think EVS attenuators are sold any longer but I could be wrong.

edit: does anybody have any opinions on the scott endlers attenuators as solution?

Anyway, thanks for the tip!

  jaspal

[Bemopti123]

I was able to manage to put the EVS attenuators in different amplifiers...Always plugging in in the amplifier end and not the source end.  If worse gets to worse, you might have to get a sort of RCA extender either a cable or something to provide you more clearance...But seeing the amp, it will fit.  You can spin the volume knobs to different directions so they are opposed and not kissing each other.  You will be fine.

Although Ric stopped production once, he is back at it.  Everyone needs some extra $$$.  They go for about $300 a pair....I have not heard the endler attenuators, but many seem to like it. 

The best thing about the EVS attenuators is that you can really experience this passive amplification sound with ANY amplifiers that you choose, in case that you decide to swap out of thr BYOB amplifier.  Funny to think that I felt it provided 90% of what my First Sound Paramount does.  Of course, it is source dependent....If source is bad, that you will have 90% of that bad sound going into the amplifier.   

I have had my pair for a good 3 years and eventhough they are not in use now, they are most helpful when you decide to tweak the gain into ANYTHING.   

[audiotone]

FWIW:
two simple resistors per channel and half an hour work by some one who can handle a soldering gun...
1-3 dollar for the finest resistors you can find, times 4 makes about 12 dollar...

a stepped attenuator ala Dact or Goldpoint would be 20-25 times more expensive = 200-300 Dollar.

I would suggest to go for the resistors and find somebody who can handle a soldering gun...a pay him a nice dinner in your favorite Italian, French or Japanese restaurant.

I like the French Cuisine...

hope you find a good solution...

[anubisgrau]

jaspal, do you use any preamps?

if so i would assume it would be better to fully bypass the BYOB pot (that anyway looks like a weak link) and use your preamp volume control.

at least that's what i would try first before adding any elements to signal path.

my new speakers have 114db eff and i plan to use them with the BYOB. most likely i won't be allowed to touch the pot.