Solupeak RC-11 Review (Passive Volume Control)

[Ra1zel]

I was shoked for a second, then I saw the dB scale on the left
So basically, this thing is about high end worthy when your amp has too much sensivity/gain - as a last resort for attenuation.

Oh, and wanna have a laugh? I wanted to see a measurement of this thing because I thought of getting one for "throttling" the input to my Hypex amps to match the Topping PA5 with about 10dB less gain, but now I see this thing isn't really available in Germany.

View attachment 210534

People here will preach about 120 SINAD and <1 uV noise and high-res audio, mqa bullshit but apparently 1dB rolloff at 20kHz is fine... OK

 

[anphex]

People here will preach about 120 SINAD and <1 uV noise and high-res audio, mqa bullshit but apparently 1dB rolloff at 20kHz is fine... OK

Some will do that, but most people in here are just looking for trustworthy independent data, and then putting it into ratio to the price everyone reaches its own personal verdict.

 

[Rja4000]

People here will preach about 120 SINAD and <1 uV noise and high-res audio, mqa bullshit but apparently 1dB rolloff at 20kHz is fine... OK

Not sure if that was clear: The one I measured above is a different device than the one Amir is reviewing.

 

[Ra1zel]

Not sure if that was clear: The one I measured above is a different device than the one Amir is reviewing.

Yes I know, but it would certainly be the same here with typical impedance and longer cable.

 

[soundwave76]

These smaller various audio accessory measurements are great, keep them coming!

 

[Jim777]

At last! The perfect ampli ...... Oh damn

Perfect amp is a "wire with gain" - just forgot to specify *positive* gain

 

[mhardy6647]

The L/R tracking is impressive for such a cheap little gizmo, actually.
One has to wonder if the (pretty respectable) performance of this particular unit is typical for any randomly-chosen unit? That's (potentially) the rub, you know?

 

[Lambda]

Would be interesting to see what kind of potentiometer they are using.
Seems like its a good one and for the price i don't think its a Alps,Bourns or Vishay.

Also is there a balanced version?

Edit:
But if the Product photos show 2 different versions and what they send out us is third version, its not very confidence inspiring.

Since they seam to uses what ever Screws and knobs are available at the moment i would not count to musch on the reliable quality of the potentiometer

 

[raindance]

Schiit Sys is very similar and works well.

 

[sergeauckland]

The input impedance of the AP is 100k along with a wide bandwidth.

A typical power amp will be ~25k with significant capacitance and various RC filters. The frequency response when driving a typical real world amplifier will not be remotely flat at typical volume positions (attenutated).

Would you like to estimate how 'remotely' ? I've used passive volume controls on several amplifiers/active loudspeakers and never measured any significant change in audio frequency response with 5m of RG59 cable or shorter lengths of any old bits of coax. It may vary a bit above 20kHz, but then who cares?

S.

 

[Lambda]

A typical power amp will be ~25k with significant capacitance and various RC filters. The frequency response when driving a typical real world amplifier will not be remotely flat at typical volume positions (attenutated).

This is one of this cases/reviews that shuld include a "worst case" trace.
Just to communicate how mush (if at all of a difference it makes).

This test scenario is easy and very reproducible but it's also way more ideal than many real world setups.
I would also include a way less then ideal setup to show how mush the whole system can influence the device under test test results.
Surly "every cases" cases cant be practical tested but some sort of non standard "worst case" can be easily made up.

 

[Loathecliff]

Perfect amp is a "wire with gain" - just forgot to specify *positive* gain

A certain Mr. Walker wasn't it?
His company had the left hand side of the editorial in HFN for many years.
(A pity their switch to stereo was such a bodge with everything powered off one transformer. The amp still sold)

 

[DSJR]

The II's were mono and in all honesty, by the time of the 33/303 (I have a lovely set here with FM3 which are stored for posterity), I'm going to stick me neck out and say the DIN connectors were more of an issue - probably my own issue but there ya go ).

 

[digicidal]

People here will preach about 120 SINAD and <1 uV noise and high-res audio, mqa bullshit but apparently 1dB rolloff at 20kHz is fine... OK

Not speaking for anyone other than myself here... but at my age I'm fine with a 5dB rolloff at 20kHz... since my ears already perform nearly a 120dB rolloff around 17kHz.

I do understand your point... but I think (regardless of age) most people have a different level of criticism for something as cheap and singular of purpose like this. Maybe?

 

[shrimp_dude]

Schiit Sys is very similar and works well.

I think these quick looks at passive pots are focused on how cheap they are. You can buy basically 3 of these shipped for 1 SYS before shipping costs.

 

[KSTR]

Stupid question maybe : Is there any higher voltage limit for those ?
I mean: Is THD or IMD increasing suddenly when you push more Volts at the input, as when an amp is saturating ?

At some point you will run into limits and distortion will increase:

• with log pots the wiper track is not homogenuous and will have different voltage coefficients for different sections of the track. Once the delta is large enough and large enough voltages are applied, it will affect distortion
• the thermal coefficient may also be non-uniform and even if it were uniform there still will be different thermal time constants along the track. Again, at some point, at low frequencies this will induce additional distortion when the currents are large enough (small pots, low values, high voltages)
• loading down the wiper with an input impedance will give rise to the same effects, for the same reasons. Plus it will cause additional 1/f current noise in the top section of the pot (notably if it is carbon)

That said, with a standard 10k log pot loaded with some typical 47k (for AC) I don't remember to have ever seen an issue in -120dB realms (other than added noise), matching your results in post #19

 

[sarumbear]

At some point you will run into limits and distortion will increase:

• with log pots the wiper track is not homogenuous and will have different voltage coefficients for different sections of the track. Once the delta is large enough and large enough voltages are applied, it will affect distortion
• the thermal coefficient may also be non-uniform and even if it were, uniform there still will be different thermal time constants along the track. Again, at some point, at low frequencies this will induce additional distortion when the currents are large enough (small pots, low values, high voltages)
• loading down the wiper with an input impedance will give rise to the same effects, for the same reasons. Plus it will cause additional 1/f current noise in the top section of the pot (notably if it is carbon)

That said, with a standard 10k log pot loaded with some typical 47k (for AC) I don't remember to have ever seen an issue in -120dB realms (other than added noise), matching your results in post #19

Aren’t all those limits exist on any analogue volume control of a pre or integrated amplifier? Should we criticise almost every analogue amplifier ever built?

 

[KSTR]

Aren’t all those limits exist on any analogue volume control of a pre or integrated amplifier?

Depends on the circuit.
If they are using the same potentiometric approach (voltage divider) with a logarithmic pot being buffered by a buffer or gain stage, then yes.
If the pot is linear and establishes the feedback path of an inverting gain stage, also drawing zero wiper current, then most of the limits have much lesser impact, if any at all.

 

[fastfreddy666]

Output impedance? Input impedance? Does it kill the dynamics by not being able to drive downstream components properly? This stuff does actually matter. I have used active and passive preamps and I prefer active all day every day.

nominal levels.

The decibel volt reference voltage is 1 VRMS = 0 dBV. The decibel unloaded reference voltage, 0 dBu, is the AC voltage required to produce 1 mW of power across a 600 Ω impedance (approximately 0.7746 VRMS. The DBu level is awkard because it's an holdover from the early telephone standards, which used 600 Ω sources and loads, and measured dissipated power in decibel-milliwatts (dBm). Modern audio equipment does not use 600 Ω matched loads, hence dBm unloaded (dBu).

A typical line out connection has an output impedance from 100 to 600 Ω, with lower values being more common in newer equipment. Line inputs present a much higher impedance, typically 10 kΩ or more. Impedance matching is not necessary because the cables used are relatively short. (1)

But with professional equipment it's more likely that balanced (in most cases: differential signaling) connections are used. Not all balanced connections are created equal though.

(1) https://www.ranecommercial.com/legacy/note126.html

 

[Nango]

".....same performance of as without the unit" .... and "being passive" .....is it empty inside?