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Coolest looking stepped attenuator


Decky
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  • 2 weeks later...
There is an interesting review in the new Tone Audio (issue 51) of Takumi K-10 preamp. What caught my eye was the volume control. Looks amazing!

 

a little beauty . wonder what resistors they used ? any one know?

 

Cheers

Duc

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What is the big deal about this attenuator?

 

Even Tone audio who generally have nothing negative to say in their advertorials complained about the lack of fine gradation in the attenuator steps. No mention anywhere what the steps are. Hopefully not something ludicrous like 3db that I have seen on so called highly regarded line stages.

Edited by turntable
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a little beauty . wonder what resistors they used ? any one know?

 

 

They are Amtrans AMRG but without the black anodised aluminium tube and potting compound.

 

If you look at the link I posted you can see the attenuation curve that they steps correspond to.

 

 

Edit: that wasn't very helpful of me! This is the data sheet: http://www.amtrans.co.jp/online/attenuator/UATS_M_J.pdf

There are three graphs, the left most one is the curve dB against steps.

Edited by nattonrice
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What is the big deal about this attenuator?

I don't know what fascination all pots have, they all have contacts of different materials and contact pressures, this is why they all sound different, they are all flawed in my view for passing a complex audio signal through.

Even a quality gold to gold rca contact which is much more solid and larger area will sound better if cleaned with contact cleaner.

What hope does the dissimilar (materials) metal wiper and carbon/plastic resistance track of a potentiometer with a pin point wiper light contact have. Something to think about!

 

Cheers George  

Edited by georgehifi
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You want the best that has contacts in the signal path? here it is, roller bearings and the works  http://www.khozmo.com/products_dale_shunt.html

 

Cheers George

 

This may be newer onto the market than when the late, great Bob Crump was sourcing cost-no-object (but must sound the best!) components for his / John Curl's "Blowtorch" preamp - so he never had a chance to evaluate it - but he chose the TKD stepped attenuator for the Blowtorch.  Then he added some series resistors to it, to make it sound even better! :D

 

Regards,

 

Andy

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Flawed as in they distort the complex audio signal passing through them?

Search and do some reading on diode effect of light contacts or dissimilar metals or materials. You will find they act like diodes trying to rectify the ac music signal.

Herve Delaratz of Dart'Zeel  with his big bucks preamp found the same thing, and uses the same system I do, the $25k Dart"Zeel NHB-18NS has no potentiometer contacts in the signal path.

 

Quote: Herve Delaratz

The volume controls do use potentiometers for convenience but the signal does not go through it. We do use a resistor ladder, but not in a conventional way.

Q: What is wrong with conventional volume controls?

A: You lose something. I use a system that varies resistance with light. However, until all the patents are in place, I would prefer not to specify the details.Quote:

http://www.6moons.com/audioreviews/dartzeel2/preamp.html

 

This is what I found way back in 1979 about pots, no matter how good they are all comprimised.

 

Cheers George

Edited by georgehifi
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Flawed as in they distort the complex audio signal passing through them?

 

Depends whether you call "degradation" a flaw, Ken! ;)

 

I agree with George - every attenuator degrades the signal ... so the trick is to find the one that degrades the signal the least. :P   Likewise any cap used for coupling duties - caps never "improve" - they only degrade! :)

 

 

Regards,

 

Andy

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Search and do some reading on diode effect of light contacts or dissimilar metals or materials. You will find they act like diodes trying to rectify the ac music signal.

 

Which would be a bad thing I would suspect and obviously something that would distort the signal.

 

Would I be wrong?

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Depends whether you call "degradation" a flaw, Ken! ;)

 

I agree with George - every attenuator degrades the signal ... so the trick is to find the one that degrades the signal the least. :P   Likewise any cap used for coupling duties - caps never "improve" - they only degrade! :)

 

 

Regards,

 

Andy

 

George has the best idea Andy,  as you probably know if it wasnt for the M51 digital volume control that totally elimimates the preamp I would have gone and utilised George's LightSpeed attenuator, if George (no offense to him but would like to point out...) has not already done so, I do recommend that he incorporates a remote control for his product and this will sell faster,  I migh even buy one to experiment.

 

I experimented with pots when I started to go DIY and the difference in coloration not only from different make and brand, even from the same batch, all sounded different.  I played with carbon, plastic film, wirewound, Alps, Allen Bradley etc.  I  discovered no matter what materials used its like George have said, they begin to deteriorate from the first turn.  I f()&^*(^n hate them with an a passion, I have no objections of people using them, even the stepped resistor that are relay switched, I personally go all out to eliminate them in my rig.

 

 

 

 

This one is not for the faint hearted if you want the best, comes in 2 values, 50&100K

 

Also being approved by the Stax Mafia at Head fi:

 

http://www.alps.com/WebObjects/catalog.woa/E/HTML/Potentiometer/RotaryPotentiometers/RK501/RK501_list.html

 

 http://www.diyaudio.com/forums/parts/43416-alps-rk50-best-volume-pot-world.html

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George has the best idea Andy,  as you probably know if it wasnt for the M51 digital volume control that totally elimimates the preamp I would have gone and utilised George's LightSpeed attenuator, if George (no offense to him but would like to point out...) has not already done so, I do recommend that he incorporates a remote control for his product and this will sell faster,  I migh even buy one to experiment.

You have to watch out when using digital domain volume controls in cdp's/dac's, yes they are the best most transparent/dynamic way of getting the music to the poweramp in fact this is what I model the sound of the Lightspeed Attenuator on.

But, and it's a BIG but, if the digital domain volume controls are not used in their top 25% of full output, you run the risk of "bit stripping" that is the lower you go from 75% of full output the less resolution you get, ie: 16bit redbook cd at full volume no problems, at half volume (50%) with digital domain volume controls it can have only 14bit or less resolution.

I'm lucky with my cdp digital volume control as it runs at about 85-90% of full output at good level for my system, this is why I A/B the Lightspeeds against it, to show there is almost no difference in sound quality either way, except for an extra pair of interconnects when the Lightspeed is used compared to direct out of the cdp.

 

BTW there is only one cdp that I know of that lets you set the amount of full output from it's digital domain volume control by setting internal gain pins/links so you set it for your system. So that full up on the digital domain volume becomes just too loud for comfort, that way it's always used in the top 25% of full output.

And that player is the best thing Mark Levinson has ever made the multibit (no delta sigma rubbish) the ML No39 cdp 4 X old school PCM1704 dac chips and a PMD-100 hdcd filter.   

 

Cheers George     

Edited by georgehifi
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I would like to give this volume control a try in a pre-amp:

 

  http://www.diysoundlab.com/index.php/vc-03-volume-control

 

I so wish I had enough electronics knowledge/skill to follow the instructions (see bottom of page). Can anyone suggest a short course or certificate I could take which would enable me to undertake such a project, or similar projects, safely and with confidence?

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@George,

It may not be as ideal as your light speed, the the M51 truncates at -66db, 35 bit( as per the NAD hype) even using the Stax Lambda Pro with a SRM-1 MK2, this is possibly as ideal a digital attenuator gets, the balance is near perfect, I listen to mostly 16/44, and I swear some recordings on red book are more enjoyable than some 24/192. I also listen to this @ -56-52db 5.00am in the morning on Mon-Fri there is almost little deviation on detail reduction, apart from what has been low in amplitude to begin with.

Eliminating the preamp altogether makes this device an unbeatable combo, and it's stable for the life of the unit, no degradation due to wear or tear. I no longer use a preamp, The transparency and smoothness and detail extraction in the main rig just prove to me the more parts count in the signal path the worst it gets!

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@George,

 I listen to mostly 16/44, and I swear some recordings on red book are more enjoyable than some 24/192.

I definately go along with that, I have yet to hear downloaded HD played back through a laptop with flawed software whatever it is, or server, sound to me better than what great Red Book replay can achieve through a cdp or dac through good old multibit R2R dac chips.

Cheers George 

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I heard the PCM 1704 via the Audio gd Ref 7.1, stunningly musical, less detail extraction compared to the M51, the M51 was analytical not as musical, one day I'm going to budget for it

I would like to give this volume control a try in a pre-amp:

 

  http://www.diysoundlab.com/index.php/vc-03-volume-control

 

I so wish I had enough electronics knowledge/skill to follow the instructions (see bottom of page). Can anyone suggest a short course or certificate I could take which would enable me to undertake such a project, or similar projects, safely and with confidence?

In the PDF supplied with this project, it is quite straight forward, the hard yards are done for you all you do is place it in a preamp and wired it in and program the remote control that you buy separately, however there are other projects that similar without the nice digital display that is a fraction of the cost

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Hi all,

Not wanting to get "drawn into" the pro's and cons of various attenuators I'll throw in my 2 cents anyway. When we first started to import Sun Audio amps I started tinkering and tweaking to get more out of what was already one of the sweetest sounding 2a3 amps I've heard. Among cables, caps, connectors and tubes I also tried LOTS of various attenuators. Some cheap others stupidly expensive. I did not find anything that matched the bog standard looking "cosmos" branded carbon pot that they came with. The amps run 2 mono pots and I was trying 2 attenuators using one channel each. The Cosmos are Japanese made and are quite a big manufacturer in terms of product lines. When I relayed my findings to Mr Uchida from Sun Audio he simply replied "I know, we can't beat them either" !

I have not tried any of the 2 shown on this post and I have been curious about George's lightspeed ever since Sam mentioned them in Stereophile. Maybe one day I'll give you a call George.

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Depends whether you call "degradation" a flaw, Ken! ;)

 

I agree with George - every attenuator degrades the signal ... so the trick is to find the one that degrades the signal the least. :P   Likewise any cap used for coupling duties - caps never "improve" - they only degrade! :)

 

 

Regards,

 

Andy

 

Hi Andy.

since we talk about degrading the signal then let me add this .

the trick is to build or buy the system that have the right gain structure so that you can use your pots or your attenuator as open as they have to be without attenuating to much of the signal. most of the system have too much gain .

 

cheers

Duc

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A Quote from the master Nelson Pass

 

Hi Andy.

since we talk about degrading the signal then let me add this .

the trick is to build or buy the system that have the right gain structure so that you can use your pots or your attenuator as open as they have to be without attenuating to much of the signal. most of the system have too much gain .

 

cheers

Duc

Exactly right, these days there are no need for pre-amplifiers (that add more gain) all one needs is an attenuator. 

A quote from god himself.

 

 

A Quote from the master Nelson Pass

 

Nelson Pass,

We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.

Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.

Routinely DIYers opt to make themselves a “passive preamp†- just an input selector and a volume control.

What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.

And yet there are guys out there who don’t care for the result. “It sucks the life out of the musicâ€, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.

 

 

Cheers George

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