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Your thoughts on stepped attenuators, please...

post #1 of 23
10/8/10 at 11:36am
Thread Starter 

I've been looking at a Goldpoint Mini-V stereo SA, since the ALPS pot in my Woo sometimes makes scratchy noises (and I also suspect channel imbalance sometimes).  I have ZERO interest in building my own, or in a "cheap" replacement, so I'm curious about what people think regarding the sonic improvements a good SA can make in an amp.  Is it worth the $150 price bump, given my system (see sig below), or are they just a little to boutiquey to merit the price?  For those that have used them, what have you noticed about them, soundwise...aside from the channel balance, do they significantly impact SQ?  Thanks for any/all input!

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post #2 of 23
10/8/10 at 12:57pm

They make quite a difference, you will notice it immediately. The clarity is much improved over something like an Alps Blue Velvet. Whether that difference is worth $150 has a lot to do with how much you're willing to invest in your system.

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post #3 of 23
10/8/10 at 2:23pm



 

Quote:
Originally Posted by HiGHFLYiN9 View Post

They make quite a difference, you will notice it immediately. The clarity is much improved over something like an Alps Blue Velvet. Whether that difference is worth $150 has a lot to do with how much you're willing to invest in your system.



 A volume control/pot/variable resistor/rhesostat call it what you like simply alters the resistance in a circuit and thus the voltage applied to the output amplification, they are not in the signal path as such are they ? , therefore how do they change "clarity" or other audio parameters apart from volume ?

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post #4 of 23
10/8/10 at 2:58pm

My vintage stereo receiver has 50 clicks. Now, due to age, the first 5 clicks have imbalance issues. Yes I DeoxIt-ed the pots.

Thing is, if the change between clicks are not so great, and you have a good range of clicks, you'll be fine. Unlike my receiver, which is able to drive a freakin' 300 ohm phone to unlistenably loud levels at 22 clicks.

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post #5 of 23
10/8/10 at 3:07pm

searching helps: http://www.head-fi.org/forum/thread/149217/stepped-attenuator-really-worth-it

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post #6 of 23
10/8/10 at 3:59pm
Thread Starter 

Yeah, thanks Ace...read that already.  In two pages of replies there were exactly TWO responses from people that a) had a good amount of actual hands-on experience with them, and b) actually discussed their opinions on the sound quality differences, which is what I was asking.  I'm looking for a few more opinions than that.  99% of the replies involved either building one or using them in a DIY amp, which is just superflous and useless info for me.  Your reply on the other hand was immensely useful to me, thanks.

 

It's not like I was asking "what amp is best for my HD650's" for the millionth time.


Edited by Golden Monkey - 10/8/10 at 4:16pm
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post #7 of 23
10/8/10 at 4:05pm
Thread Starter 
Quote:
Originally Posted by nick_charles View Post



 



 A volume control/pot/variable resistor/rhesostat call it what you like simply alters the resistance in a circuit and thus the voltage applied to the output amplification, they are not in the signal path as such are they ? , therefore how do they change "clarity" or other audio parameters apart from volume ?



That's what I wonder as well...if it WAS in the signal path then I could see it having an impact on the sound quality.  I would think that anything in the signal path would.  But if it's just adjusting voltage by adding/subtracting resistance, it is outside of the signal path...at least as I understand it...confoozled.

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post #8 of 23
10/8/10 at 4:11pm
Quote:
Originally Posted by nick_charles View Post

 A volume control/pot/variable resistor/rhesostat call it what you like simply alters the resistance in a circuit and thus the voltage applied to the output amplification, they are not in the signal path as such are they ? , therefore how do they change "clarity" or other audio parameters apart from volume ?


It depends on the application, but in the case of a typical headphone amplifier, yes, they are directly in the signal path. Take a look at this Bottlehead amp I built. You'll notice the RCAs wire directly to the potentiometer, in this case a stepped attenuator by DACT.

 

Crack-Inside.jpg

 

 

Typically a potentiometer is made from a carbon/graphite wheel, if you have discreet resistors, like in a stepped attenuator, it usually sounds preferable. We can then get into different resistors and stepped attenuator types. There are series, ladder and shunt stepped attenuators with the resistors wired in different configurations, and they can be wired with carbon comp, carbon film and metal film resistors to name a few. These all have various effects on sound quality, although not as pronounced as upgrades in iron or coupling capacitors.

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post #9 of 23
10/8/10 at 4:30pm
Thread Starter 

In that particular amp, I can definitely see that it would make a difference, since it is between the line-level signal and the rest of the circuit, if I'm reading that correctly...

 

HiGHFLYiN, in the thread Mr. Helpful linked, you said "Now SAs don't always work well in all amps, for example the WooAudio3 was not receptive to either one as the volume range didn't go across the whole spectrum"...what did you mean by this exactly?  If the SA was turned all the way down, you could still hear the signal, and all the up wasn't full volume?


Edited by Golden Monkey - 10/8/10 at 4:32pm
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post #10 of 23
10/8/10 at 5:05pm
Quote:
Originally Posted by HiGHFLYiN9 View Post


It depends on the application, but in the case of a typical headphone amplifier, yes, they are directly in the signal path. Take a look at this Bottlehead amp I built. You'll notice the RCAs wire directly to the potentiometer, in this case a stepped attenuator by DACT.

 

Crack-Inside.jpg

 



Ah, thanks for that explanation , I miisunderstood the architecture

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post #11 of 23
10/9/10 at 9:02am
Quote:
Originally Posted by Golden Monkey View Post

In that particular amp, I can definitely see that it would make a difference, since it is between the line-level signal and the rest of the circuit, if I'm reading that correctly...

 

HiGHFLYiN, in the thread Mr. Helpful linked, you said "Now SAs don't always work well in all amps, for example the WooAudio3 was not receptive to either one as the volume range didn't go across the whole spectrum"...what did you mean by this exactly?  If the SA was turned all the way down, you could still hear the signal, and all the up wasn't full volume?


Right, I tried the DACT and a chinese stepper in the WooAudio3 and didn't really care for the results as it was difficult to get the volume at a suitable listening level with the 24 steps. Basically the gain is high enough that you really only get to play with a few different steps around 9 o'clock. If you built one on a logarithmic scale (rather than linear) this issue would disappear, or you could investigate a higher quality potentiometer like the TKD. Partsconnexion sells them for ~$75 and they should be a nice step up from the blue velvet. 

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post #12 of 23
10/10/10 at 11:37am

 

Originally Posted by Golden Monkey View Post

 

Your reply on the other hand was immensely useful to me, thanks.


You're most welcome I'll give you that the search engine has become pointless since the switch...some links you might fancy:

 

http://diyaudio.co.kr/wwwboard1/data/board1/compare.pdf

 

http://www.dact.com/html/attenuator_data_sheet.html


Edited by leeperry - 10/10/10 at 11:38am
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post #13 of 23
10/10/10 at 3:10pm
Thread Starter 
Quote:
Originally Posted by HiGHFLYiN9 View Post


Right, I tried the DACT and a chinese stepper in the WooAudio3 and didn't really care for the results as it was difficult to get the volume at a suitable listening level with the 24 steps. Basically the gain is high enough that you really only get to play with a few different steps around 9 o'clock. If you built one on a logarithmic scale (rather than linear) this issue would disappear, or you could investigate a higher quality potentiometer like the TKD. Partsconnexion sells them for ~$75 and they should be a nice step up from the blue velvet. 

 

Do you think the issue may have been an incorrect resistance value for the attenuators?  What resistance value did you use (and related to that question, what value would you recommend in a WA3+)?
 

Quote:
Originally Posted by leeperry View Post

 


You're most welcome I'll give you that the search engine has become pointless since the switch...some links you might fancy:

 

http://diyaudio.co.kr/wwwboard1/data/board1/compare.pdf

 

http://www.dact.com/html/attenuator_data_sheet.html


Lol...thanks, those are both really helpful, much appreciated. 

 

Looks like the DACT CT2 is the way to go, but I wonder how they compare to the Goldpoint models...I doubt there's much info out there comparing the two (at least nothing I could find...).
 

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post #14 of 23
10/10/10 at 6:11pm
It's 100k if I recall correctly, it's what the circuit had in it initially.
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post #15 of 23
10/10/10 at 6:28pm

My Builder (chrisIvanaudio.com) has showed me, Why Daven is the only POT he builds with....They're BIG But built to last and the feel of the sweep lets you know you're dealing with the Rolls Royce of Vol. Controlled potentiometers... I've never had any issues with noise, glitches etc with the Four he's used on my gear! (2 on my Pre-amp and 2 on my new Headphone/Pre-amp)!!!! But I did find this guy's opinion on Daven Pots on a different forum, He answers this guy!                       Question " > Is the Daven or Shallco (or equivalent) better than building your own?

His reply: If you'd ever opened a Daven, you wouldn't ask that. He goes on to explain, below.

It is the difference between a 1939 John Deere farm tractor, and a $99 PepBoys lawnmower. Both cut grass, but everything about the Deere (or Daven) is 10 times bigger and will last 100 times as long, without buzzes and rattles and pieces falling off.  I found that to be an interesting (But Truthful statement).......................................google Daven Pots, if you want more info ....PS now these aren't "little itty bitty"vol.pots......
 

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