Lundahl Sound VC2361 6-Channel Volume Control Review

[amirm]

This is a review and detailed measurements of the Lundahl Sound Systems VC2361 Balanced Multichannel Volume Control. It was sent to me by the Swedish company and I am told it represents final production. Cost is 12kSEK + VAT or US $1,110 plus shipping.

I must say I was expecting a "Pro" looking device, not an attractive consumer looking packaging. Turning the nice feeling rotary control is accompanies by relays clicking indicating stepped relay control. Considering how many channels they have to control, this is likely an expensive implementation but assures precision channel matching. And availability of remote control:

A Meanwell external power supply is provided. In this class of product, I would have wished an internal power supply.

Lundahl Volume Control Measurements
Let's start with a reference of my Audio Precision APx555 looping using its internal relay from input to output:

Now we loop through the Lundahl:

Max gain is not 0 dB translating to the output being slightly less than 4 volts. That likely caused a corresponding hit on SNR reducing SINAD by a negligible 1 dB.

I was a bit disappointed that the frequency response was not more extended and matched between channels:

Won't impact audibility though.

I was pleasantly surprised that I could not make the Lundahl clip even with the maximum 26 volt output that my generator can output:

There is a small noise penalty at lower levels but we are still talking transparency. Lowering the volume setting has no impact.

There is no frequency dependency with performance being state of the art:

IMD shows a bit more distortion at higher output levels but still excellent:

Finally, crosstalk is superb whether we are looking at adjacent channels or far:

Conclusions
The market offering for multi-channel volume controls is limited. I remember having a Pro one at Microsoft years ago and it was fairly noisy. The Lundahl volume control on the other hand delivers superb performance with just a tiny bit of room left for improvement. It is also a very attractive product with nice functionality of a remote control.

I am happy to recommend the Lundahl Sound Systems VC2361 6-channel balanced Volume Control.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[OctoEmu]

Very nice product, hopefully the price is reasonable!

 

[bachatero]

Does this use a ADC+DSP+DAC chain or a straight up analog one? Because it looks suspiciously distortion-free for anything digital.

 

[amirm]

Purely analog. Volume control is digital but the path is analog.

 

[amirm]

Just read that it is passive. No wonder it doesn't care about input voltage. Here is the impedance range:

Input Impedance
6kOhm is @ 0dB attenuation.
360kOhm is @ -64dB attenuation.

 

[pseudoid]

Thank you for the review, @amirm,
Internal power supply would have probably added to the cost and may have caused 'bumps'.

I remember having a Pro one at Microsoft years ago and it was fairly noisy.

Part of me wants to ask what you used it for but it was outvoted.

 

[amirm]

Part of me wants to ask what you used it for but it was outvoted.

It was a switcher and master volume control. We used to make comparisons of two different multichannel systems playing the content.

 

[bachatero]

Purely analog. Volume control is digital but the path is analog.

If the path is 100% analog but the volume control part is digital, how does it control the volume in an analog manner using digital components, unless it's physically moving some potentiometer?

 

[georgehifi]

Input Impedance
6kOhm is @ 0dB attenuation.

Pity it's not higher, as it may not suit everyone.
If a source component has a capacitor coupled output (like most tubes have), and using say a .5uf polypropylene coupling cap, then the bass roll off will already be -3db down at 53hz! Not good for low bass on full range speakers.

Cheers George

 

[amirm]

If the path is 100% analog but the volume control part is digital, how does it control the volume in an analog manner using digital components, unless it's physically moving some potentiometer?

It switches between different sets of resistors using relay. The resistors act like voltage dividers and hence, adjust the gain. The drawback is that the impedance of the device changes as volume is changed.

 

[DVDdoug]

If the path is 100% analog but the volume control part is digital, how does it control the volume in an analog manner using digital components, unless it's physically moving some potentiometer?

Relays switching resistors in & out of the circuit.

A Meanwell external power supply is provided. In this class of product, I would have wished an internal power supply.

The engineering-side of my brain says keep it external for noise isolation. The marketing & consumer-side of my brain says internal power supply is "more professional" and looks "less cheap".

 

[pma]

Please correct the typo, it is Lundahl, not Lundalh.

 

[bachatero]

It switches between different sets of resistors using relay. The resistors act like voltage dividers and hence, adjust the gain. The drawback is that the impedance of the device changes as volume is changed.

I don't want to sound like a complainer, but that sounds like the worst thing ever, because you don't know what's on the other end of that impedance, and the figures you gave are basically in impedance mismatch territory. Who engineered this?

 

[Blumlein 88]

Whether I approve depends upon pricing. Good performance for sure. Are these the transformer guys? Surprised they didn't use them.

 

[amirm]

Lundahl makes audio transformers some of which are stepped "Autoformers" so the relays are probably clicking between taps on the autoformer.

They transformer would have made quite an impact on the measurements. Here is a quote from spec sheet:

"The VC2361 is a high-performance multi-channel volume control that enables up to six audio channels to be simultaneously attenuated in the analogue domain. The audio circuits are entirely passive and fully balanced to provide maximum performance and transparency. An extraordinarily high precision in channel-balance is enabled by a relay-based design, where discrete metal film resistors with ultra-low variance are utilized to provide the required attenuation."

 

[amirm]

How many volume steps were there ?

64 steps in 1 dB increments.

 

[amirm]

Are these the transformer guys? Surprised they didn't use them.

No, a different company: https://www.lundahlsoundsystems.com/#optimizer_front_text-4

 

[amirm]

I don't want to sound like a complainer, but that sounds like the worst thing ever, because you don't know what's on the other end of that impedance, and the figures you gave are basically in impedance mismatch territory. Who engineered this?

We don't match impedances in audio. It is the nature of passive volume controls to change impedance. You need to look at the rest of your system and figure out what the impact is.

 

[Blumlein 88]

They transformer would have made quite an impact on the measurements. Here is a quote from spec sheet:

"The VC2361 is a high-performance multi-channel volume control that enables up to six audio channels to be simultaneously attenuated in the analogue domain. The audio circuits are entirely passive and fully balanced to provide maximum performance and transparency. An extraordinarily high precision in channel-balance is enabled by a relay-based design, where discrete metal film resistors with ultra-low variance are utilized to provide the required attenuation."

Any info on the resisters used? Vishay foil are the best I am aware of being available. Precise, I think a 1 ppm temp coeffiicent.

 

[amirm]

I don't see anything about that in the spec sheet. Speaking of that, here are the specs: