Goldpoint SA2X - Nobsound NS-05P passive attenuator comparison technical measurements

PSA: Nobsound NS-05P specifications on Amazon were updated and now show impedance as 10K.

So another was acquired and measured for DC resistance. Unfortunately the unit received measures approximately 50K. My guess is there is a bit of stock to be sold (flushed) before the change takes effect. Unit returned.

Buyer beware.

 

I wonder if there's any with 10k yet I would order one ...

 

I was thinking about grabbing a Nobsound from Amazon as well, but not sure about the 50k pot issue. I’m not clear from previous posts (sorry if I missed it) but I assume there is no way to just eyeball whether you have the 10k pot version based on a number or something on the pot? It has to be measured to determine it? The pic from @atomicbob from the top of the inside of the unit doesn’t seem to show it...

 

Amazon spec has been returned to 50K. I suspect there is backstock to sell before implementing a change. No simple way to verify other than use a DMM. You can get one for $10 US here:
https://www.amazon.com/AstroAI-Digital-Multimeter-Voltage-Tester/dp/B01ISAMUA6/

Measure input XLR to see the following (approximate) readings:
Pins 1 - 2 10K
Pins 1 - 3 10K
Pins 2 - 3 20K

 

Got the nobsound for my LP. So nice to have more than 2 degrees available on the dial for the Clears.
Both pots at 10 0'clockish. FWIW, a lil slip of paper says 20K, but it's 50K

 

atomicbob,

I’m currently using a Nobsound 50k. I need a lot of attenuation, so I normally set the pot at 9 o’clock. I’m guessing this is around 30db. You mentioned that at more than 20db, frequency rolloff should not be an issue with the Nobsound. That’s good.

However, I’m not totally clear on all the other differences (gain linearity, crosstalk, residual noise, transient response, channel imbalance).

Could you say if these are dependent on:

1) The level of attenuation
2) Size of the pot
3) Quality of the pot

I don’t really have a choice on the size of the pot, or the level of attenuation. However, I would be happy to change it for a higher quality 50k pot if It addresses these differences.

 

atomicbob/anyone:

I'm trying to measure the resistance as you described in post #25 above, and am getting different numbers. I'm getting:

Pins 1 - 2 9K
Pins 1 - 3 8.32K
Pins 2 - 3 17.59K

I tried taking the Nobsound apart, but after I remove all the screws, can't figure out how to get the case apart.
Any suggestions on that as well?

Thanks.

 

Level of attenuation has first order effect on frequency response only. The others aren't worth worrying about. Quality of pot has effect on channel imbalance but to reduce channel imbalance requires stepped attenuator with precision resistors. Size of pot matters only if you are planning to run power through the pot which doesn't apply in this situation. The real issue is the pot should be 10K not 50K for best performance between 6 and 20 dB of attenuation.

It appears you are either measuring the output connectors rather than the input connectors or have something connected to the output while measuring. Measurements should be made with the Nobsound disconnected from everything.

 

atomicbob:

Thanks for your reply. I'm definintely measuring the input connectors. Is there something wrong with the POT in my unit?

 

I currently have the nobsound SA2X, which I love, though I am curious about the "At least 20dB" part with the nobsound. And how this applies to the SA2X.

My chain is currently: Holo May (54ohm Output impedance) --> Goldpoint SA2X --> Benchmark AHB2 (50kOhm Input impedance)

With susvara I am typically listening at 4-8 positions from max (so 6-12dB on the 47 step version).
My cables are 0.5m long.

is there any reason to assume this configuration would cause an issue? I'm a little unclear on why it would be "at least" 20dB instead of "less than". Wouldn't less attenuation be more ideal? (Not in any way arguing, just interested to learn more myself as I don't fully understand it)

Thank you for the fantastic measurements though!

 

Also, in case anyone might find it interesting, Goldpoint provided me with this sheet showing the resistor values, the sa*X series is 10k 1.5dB on the 47 step version by default

 

Hello,
what cable length and type would you advise to use between DAC and Passive Attenuator? Does lower capacitance short cable is better too?
Thanks.

 

The shortest length that allows you to connect your components is the correct length. Less than 3 meters is preferable. Above 6 meters enters the area where high frequency loss MAY become an issue.

 

Thanks!

 

atomicbob, at your opinion, if I purchase SAS2X-47 not with 1,5 dB step (-67.5bB up to 0dB) attenuation but with 1dB step (-45dB to 0 db) - will it affect some way the high frequency roll off in the range -20 to 0 dB? I think it should be the same, right?

Thanks.

 

I am not @atomicbob but as far as I understand as long as the impedance is 10 k in both cases whether you go to 6 dB attenuation in four or six steps should not make a difference in regards to the high frequency roll off.

@GoldenOne

The higher the impedance of the attenuator for the given input impedance of your amplifier the more pronounced the roll off will be. The impedance is maximum for 6 dB attenuation, with more attenuation the impedance will be lower and the roll off less pronounced.

 

@mitochondrium answer is correct. There will be no difference other than the gain step size unless you change the stepped attenuator from the default 10K input.

 

Thanks for the info. The input impedance of my active monitors is the same, 10 kOhms. So, it should be ok I think

 

If I would need to use SAS2X (with 2 inputs and 1 output) with 0 dB attenuation, just like an input switcher - will it make high frequency roll off at 0 attenuation? Or does the roll off start when attenuation is applied (~ -1 dB to -20dB)?
Thanks.