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Alps RK50

post #1 of 14
12/11/09 at 7:31pm
Thread Starter 
I recently bought a KGSS here on the FS forums but one of the decks of the attenuator (made by Singlepower incidentally) is acting up. Basically, occasionally it doesn't attenuate.

I'm considering replacing it with am alps RK50. Is this overkill for a KGSS? Is it really that much better than (say) a DACT?

Also, are there any other highend alternatives?
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post #2 of 14
12/11/09 at 8:06pm
I think any reasonably well-designed attenuator will outperform even an RK50 in channel balance and other measurements. I haven't heard anything with an RK50, so no further comments.
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post #3 of 14
12/11/09 at 9:04pm
With anything Single Power has touched, check the soldering. It's usually ranging from quite bad to horrible. The problem could be elsewhere though since I doubt Headamp ever used SP attenuators so it could be an after market mod.

As for the RK50, I would pick it over any stepper but there are some issues with it. The sheer size of the thing, cost and that you either need to modify any knob you are going to use with it or find one for the 8mm shaft.
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post #4 of 14
12/11/09 at 11:25pm
Thread Starter 
Quote:
Originally Posted by spritzer View Post
With anything Single Power has touched, check the soldering. It's usually ranging from quite bad to horrible. The problem could be elsewhere though since I doubt Headamp ever used SP attenuators so it could be an after market mod.
Actually my KGSS is not built by headamp.

Quote:
Originally Posted by spritzer View Post
As for the RK50, I would pick it over any stepper but there are some issues with it. The sheer size of the thing, cost and that you either need to modify any knob you are going to use with it or find one for the 8mm shaft.
[/QUOTE]

Is the reason you'd pick the RK50 because of sound quality or build quality? Wow, 8mm would definitely cause some problems though!
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post #5 of 14
12/12/09 at 12:10am
Quote:
Originally Posted by XXII View Post
Also, are there any other highend alternatives?
Penny & Giles RF-15.



Every bit as good as the RK50 in my opinion (though personally I think the RK50 looks sexier).

Mike LeFevre at MagneQuest has some 10k stereo units he's selling for $200.

se
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post #6 of 14
12/12/09 at 12:52am
Thread Starter 
Quote:
Originally Posted by Koyaan I. Sqatsi View Post
Penny & Giles RF-15.



Every bit as good as the RK50 in my opinion (though personally I think the RK50 looks sexier).

Mike LeFevre at MagneQuest has some 10k stereo units he's selling for $200.

se
Thanks! I might try this. I think I need a 50k pot and from the datasheet, it only seems to go up to 10k. Sorry for the newb question, but what happens if I use a 10k pot instead of a 50k pot?

Also, I need a balanced one. Any suggestions on where I can get one?
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post #7 of 14
12/12/09 at 2:13am
Quote:
Originally Posted by XXII View Post
Thanks! I might try this. I think I need a 50k pot and from the datasheet, it only seems to go up to 10k. Sorry for the newb question, but what happens if I use a 10k pot instead of a 50k pot?
Shouldn't have any issues going from 50k to 10k.

Quote:
Also, I need a balanced one. Any suggestions on where I can get one?
According to P&G, these guys:

Control Devices

se
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post #8 of 14
12/12/09 at 7:31am
Quote:
Originally Posted by XXII View Post
Actually my KGSS is not built by headamp.
Ahhh I missed Rockhopper part in your sig. It's very well built amp but I would remove the attenuator and look for bad solder joints. The exact same attenuators made by Goldpoint are very reliable and well made but with SP, the odds are stacked against it.

Quote:
Originally Posted by XXII View Post
Is the reason you'd pick the RK50 because of sound quality or build quality? Wow, 8mm would definitely cause some problems though!
Well I loath steppers because I can never get the right volume level. I also prefer the sound of pots in general (the good ones are more neutral to my ears) but the limited range of impedance available in 4 gang units is indeed a problem so now I'm waiting for my 100 custom made 4-gang 50k pots.

The RF15 is also a good choice but again the max 10K impedance can be a problem. It all really depends on what source you are using since its output impedance should be 1/10th or less of the pots impedance. Very few sources are 5K or more so most manufacturers use 50K pots with the penalty of adding a bit of noise.
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post #9 of 14
12/12/09 at 7:42am
Quote:
Originally Posted by Koyaan I. Sqatsi View Post
Shouldn't have any issues going from 50k to 10k.
Not to step on any toes, but the OP should make sure that any source equipment that he intends to use with a 10k pot has a sufficiently low output impedance (ie. < 1k) and also if it is cap coupled on the output, that the values are sufficient for a 10K load, with which they will form a high pass filter.
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post #10 of 14
12/12/09 at 1:32pm
Quote:
Originally Posted by Parafeed View Post
Not to step on any toes, but the OP should make sure that any source equipment that he intends to use with a 10k pot has a sufficiently low output impedance (ie. < 1k) and also if it is cap coupled on the output, that the values are sufficient for a 10K load, with which they will form a high pass filter.
Yes, I'm aware of that. And that the tube folks often shriek in horror when they hear "10k."

But keep in mind that he'll be using it balanced, so the load in question is 20k, not 10k. Of course that may be cold comfort for particularly asthmatic tube output stages, but shouldn't present any problems with the SFD-2. Particularly if it's the Mk. II version.

se
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post #11 of 14
12/12/09 at 2:04pm
Quote:
Originally Posted by Koyaan I. Sqatsi View Post
Yes, I'm aware of that.
I know you are!

Quote:
Originally Posted by Koyaan I. Sqatsi View Post
And that the tube folks often shriek in horror when they hear "10k."
Exactly! Without mentioning any names there are a few high end tube dacs and phono stages that have what could be considered (by me at least) to have too high a output impedance and too small coupling caps for driving a 10k load or even 20k balanced.
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post #12 of 14
12/12/09 at 4:04pm
Quote:
Originally Posted by Parafeed View Post
I know you are!
And I know you knew I am.

Quote:
Exactly! Without mentioning any names there are a few high end tube dacs and phono stages that have what could be considered (by me at least) to have too high a output impedance and too small coupling caps for driving a 10k load or even 20k balanced.
Yes. Though they generally don't have balanced outputs.

se
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post #13 of 14
12/15/09 at 11:48pm
Thread Starter 
Thanks for the answers. It turns out that the output impedence goes up to 8 kOhms so if you follow the 1:10 rule, 20k isn't enough which excludes the P&G.

I found a local place that has a discount on DACTs so I'm just going to go with that for the mean time. In the future, I'm probably gonna go for a DIY attenuator based on a SG Seiden switch:

SEIDEN Products

I need to wait until I have LOTS of time on my hands though!
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post #14 of 14
12/23/09 at 3:05pm
i would go with koyaan
he seems knowledgeable
hehe
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