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Hifi preamp vs passive monitor controllers

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Hifi preamp vs passive monitor controllers

Postby Dan B » Thu Mar 08, 2018 11:49 am

I'm wondering whether it's worth replacing my current "monitor controller" - a Cambridge Audio C500 hifi preamp - with a (probably passive) monitor controller, like the M-Patch SM 2 or Mackie Big Knob passive. Is that likely to result in an appreciable improvement in fidelity? If so, what controller would you recommend (without spending a fortune...!)

I would have thought, perhaps naively, that a dedicated passive monitor controller ought to outperform the C500... Yet I see from Gregory Scott - ubk: "Passive 'systems' have the elegance of simplicity, but they present impedance issues both to the device feeding them and the device they feed, with the latter being much more susceptible to shifts in tone and transient response as a result."

Current setup:
- RME UCX via fairly long (maybe 8m) unbalanced cable run to C500 as a source selector and volume controller. Those could be switched to a balanced run with a passive monitor controller.
- Outputs to (via a c.1m cable): (a) Flying Mole DAD 100 Pro amps and PMC TB2+ (and passive XB1 sub); (b) Pioneer A400 amp and Rega Kyte speakers.
- Room is fairly small (c. 3m x 5m) but very well treated.
- I have various other sources (e.g. CD player, other sound cards, etc) connected either directly (or via a Mackie VLZ mixer) into the C500. The proposal here would be to connect the RME to channel one of the monitor controller (as that's the priority for clean audio - it's the output for mixing), and then take the recording out of the C500 into channel 2 of the monitor controller to preserve the input selection options.

The C500:
- Supposedly one of the better budget hifi preamps. E.g. http://www.audioreview.com/product/amplification/preamplifiers/cambridge-audio/c500.html
- From the manual:
"The C500 design adheres to the principles of true hi-fi.
High precision, low noise, shielded pre-amplifier circuits,
utilising stabilised power supplies, result in an amplifier
with a staggering price performance ratio. Signal paths
within the amplifier are all as short as possible and together
with a direct switch that bypasses the tone controls, the
topology is fully optimised to give a great sound stage and
dynamic, freely flowing sound.
Inclusions such as a custom designed high efficiency audio
grade transformer, metal film resistors, multiple audio
grade capacitors and a high quality, unity gain, low noise
output buffer further reinforce this amplifiers audiophile
identity.
Completing its impressive specification, the C500 has a
specially selected high quality volume potentiometer, bass
and treble controls, five line-level inputs and a tape monitor
function.

Input Sensitivity for 750mV Output: Input Sensitivity for 750mV Output:
MD/Tuner/CD/AV/Aux/Tape: 300mV
Phono (optional board): 1.75mV
Input Impedance: Input Impedance: 47k Input Impedance: Ω
Gain: (x2.5) 8dB
Frequency Response: Frequency Response:
<10Hz to 120kHz (-0.5dB points)
Tone Controls: one Controls: Bass ±6dB @100Hz
Treble ±6dB @10kHz
Channel Separation: Channel Separation:
At 1kHz better than 72dB
Distortion: Distortion: Less than 0.01%
Signal Noise Ratio (A weighted): Signal Noise Ratio (A weighted):
92dB @ full output power
Dimensions(mm): Dimensions(mm):
90(h)x430(w)x300(d)
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Re: Hifi preamp vs passive monitor controllers

Postby Forum Admin » Thu Mar 08, 2018 12:41 pm

Hi Dan,

I use an SM Pro M-Patch 2 monitor controller, which I replaced my non-passive Mackie Big Knob with when I upgraded my monitors. I use it free-standing on the desk, so I can press its hardware Mute switch to kill all audio should howl round etc happen. Mostly I mute in my DAW's main stereo bus.

Having a Mute to hand in my opinion is an advantage over using a hi-fi amp, since they tend not IME to have them, and rely on you turning down to mute (which makes returning to your exact previous monitoring level more difficult). The M-Patch 2 offers two calibrated volume knobs -- one for main Stereo Volume and one for Aux Volume. Since I calibrated my listening level and never change the rear-panel volume settings on any of my monitors (once they've been set up), I personally like this arrangement.

So +1 for the M-Patch 2 from me - though I recall they'd stopped making them and JBL bought the rights and do their version of it, which is visually and functionally and technically identical apart from the logo difference.

The PDF manual for the JBL version is here.

I have to say I did prefer the angled desktop layout of my old Big Knob, but when I needed to change Mackie didn't offer a true passive design. Unless I missed them, we haven't yet reviewed any of their new range in SOS and I do believe the passive non-interface model is attractively priced.

A PreSonus Monitor Station V2 is an alternative consideration. It handles 3 sets of monitors (M-Patch2 covers only two stereo pairs). They go for around £260 new, and there are always some bargains on eBay.
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Re: Hifi preamp vs passive monitor controllers

Postby Hugh Robjohns » Thu Mar 08, 2018 12:44 pm

Dan B wrote:Is that likely to result in an appreciable improvement in fidelity?

Possibly -- but mostly because you'd be removing 8m-long unbalanced connections! :o

... "Passive 'systems' have the elegance of simplicity, but they present impedance issues both to the device feeding them and the device they feed, with the latter being much more susceptible to shifts in tone and transient response as a result."

It's all true. Passive controllers have their place, but if they are not well-designed and carefully matched to the connected equipment (in terms of impedances, particularly) the performance can suffer -- and sometimes quite dramatically. A good quality active controller will always out-perform a passive design, as well as being a lot more flexible. However, a lot of budget active 'monitor controllers' aren't 'well-designed'... :(

Cambridge Audio make some good stuff, and I'm sure the C500 is a great hifi preamp... but it's not a 'monitor controller', and by the sound of it you're using it just as a source selector and volume knob.

A 'monitor controller' should do much more than that. It should allow you to analyse the signal, mute or dim the monitoring signal, check mono compatibility, check the stereo difference signal, check channel polarity, check each channel individually, work reliably at a reference listening level, route the signal to alternative 'grot-box' speakers, and so on... and the better ones will also allow matching of different input source levels for meaningful comparison purposes, and balance the levels to different speakers, too.

If you don't want or need any of that (or if you rely on your DAW's facilities for much of it), and you don't have any ground-loop hum or interference issues with your current set up, my recommendation would be to stick with what you've got.

But if you want a real, high-quality monitor controller without breaking the bank, I'd consider one of the excellent designs on offer from Drawmer. Eg:

Image

https://www.soundonsound.com/reviews/drawmer-cmc2

http://www.drawmer.com/products/monitor_controller/cmc2_compact_monitor_controller.php?sort=series&series=moncon
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Re: Hifi preamp vs passive monitor controllers

Postby Dan B » Thu Mar 08, 2018 1:00 pm

Many thanks for the replies so far.

Hugh - yes, I really only need a source selector and volume control with 2 sets of outputs for the two sets of speakers. I can "mono" things in software, and don't think I'd benefit from the other monitor controller features (though might be wrong!).

Ideally I'd get rid of the unbalanced cable run, but I'm not suffering any noise from that (although no doubt some degradation).

There do seem to be concerns about reliability and the impact on signal of the M Patch, and I'm loathe to spend money for a system that won't lead to a sonic improvement or won't last long. That said, some of the better solutions - e.g. Goldpoint SA2x, Drawmer MC21 or SPL 2 Level - are in the £400 to £650 territory. For that sort of money I'd probably rather save it towards upgrading monitors (which I suspect would make a bigger difference) and/or simply plugging directly into the power amps (ideally using balanced cables) for really critical mixing...
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Re: Hifi preamp vs passive monitor controllers

Postby James Perrett » Thu Mar 08, 2018 2:35 pm

The Drawmer that Hugh showed is only about £200 and would probably be a better choice than a passive controller.
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Re: Hifi preamp vs passive monitor controllers

Postby Dan B » Thu Mar 08, 2018 3:08 pm

James Perrett wrote:The Drawmer that Hugh showed is only about £200 and would probably be a better choice than a passive controller.

Thanks James - good spot. I was looking at the 2.1, but the CMC2 would be perfect and is half the price. That's kinda tempting... Anything else I should be considering? Sonic performance is the priority (well, balanced against price!). I'm guessing the CMC2 is a fair bit more transparent than something like the M Patch.
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Re: Hifi preamp vs passive monitor controllers

Postby Forum Admin » Thu Mar 08, 2018 3:17 pm

Dan B wrote:I'm guessing the CMC2 is a fair bit more transparent than something like the M Patch.

As I said earlier, I ditched my MkI Mackie Big Knob (an active unit) because it did colour the monitoring signal. I didn't notice it so much on my KRK Rokit and NS10M monitors at the time, but when I got my larger PreSonus Sceptre 8s, I could hear it. Martin Walker and others recommended the M-Patch2, and so I opted for it.

I cannot hear any colouration on either its stereo 1 (main) or stereo 2 (aux) outputs, and I run them balanced in and out, fed by my PreSonus Studio 192 interface's main outs.
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Re: Hifi preamp vs passive monitor controllers

Postby Hugh Robjohns » Thu Mar 08, 2018 3:17 pm

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Re: Hifi preamp vs passive monitor controllers

Postby Hugh Robjohns » Thu Mar 08, 2018 3:27 pm

Forum Admin wrote:As I said earlier, I ditched my MkI Mackie Big Knob (an active unit) because it did colour the monitoring signal. I didn't notice it so much on my KRK Rokit and NS10M monitors at the time, but when I got my larger PreSonus Sceptre 8s, I could hear it.

I never understood why the Big-Knob seemed so popular. I know it has lots of facilities but it is/was both noisy and coloured -- and quite obviously so to my ears. But as you say, in the context of budget project studio monitoring perhaps its weaknesses still weren't the weakest link for many. ;)

Martin Walker and others recommended the M-Patch2, and so I opted for it. I cannot hear any colouration on either its stereo 1 (main) or stereo 2 (aux) outputs, and I run them balanced in and out, fed by my PreSonus Studio 192 interface's main outs.

The M-Patch is a good product, and in the right situations will perform very well... With short connecting cables and active speakers (or power amps) with a pretty high input impedance it will do the job well.

...but I'd still go for one of the Drawmer actives. The tech specs are top-notch excellent and the performance isn't dependent on what it's connected to, or how long the cables are.

And it lets you check the mono sum on a dedicated speaker, check channel phasing, and listen to the Stereo-Difference signal, all at the touch of a button -- things I genuinely couldn't work without! The M-Patch can't do any of those things....

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Re: Hifi preamp vs passive monitor controllers

Postby Luke W » Thu Mar 08, 2018 4:32 pm

The Drawmer units look really interesting. I've been doing a bit of monitor controller research recently, and it's surprising how many simple features are missing from so many controllers, even in a lot of the high end products.
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Re: Hifi preamp vs passive monitor controllers

Postby Dan B » Thu Mar 08, 2018 4:42 pm

Very tempted by the CMC2. The form factor of the 2.1 would suit my space much better, but since I don't need the extra features, that's quite a premium to pay. It'd be interesting to see how it compares to the C500. I guess that'd be a case of recording the same thing looped through the CMC2 and the C500 and seeing what the difference is (?). There's probably a more scientific approach...! It'd be good to know what the C500 specs are, but I've not been able to find anything beyond what I've posted above and doubt Cambridge Audio will be able to provide anything now, given that it was discontinued some years ago (I've asked them all the same though...!).
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Re: Hifi preamp vs passive monitor controllers

Postby Matt Houghton » Thu Mar 08, 2018 4:51 pm

Hugh Robjohns wrote:I never understood why the Big-Knob seemed so popular. I know it has lots of facilities but it is/was both noisy and coloured -- and quite obviously so to my ears.

I like to think it was down to the profusion of nob gags in Mike Senior's review... but it's probably because Mackie had such a good reputation in the project studio market at the time, with much less by way of competition than today... In particular, the 8 Buss consoles were popular in that market... and I don't think it's a coincidence that the Big Knob came out when a lot of people were ditching their 24/32:8 Buss desks and extenders in favour of a more compact arrangement!
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Re: Hifi preamp vs passive monitor controllers

Postby Forum Admin » Thu Mar 08, 2018 5:46 pm

Matt, Mike didn't review it -- it was Paul White:

https://www.soundonsound.com/reviews/mackie-big-knob

I bought it 'cos a) Paul White had one and rated it... b) my ears aren't as good as Hugh's... c) there was very little competition back in 2005 and Big Knob, as you say, piggy-backed on the popularity at the time of Mackie's CR and VLZ and 8-buss mixers.
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Re: Hifi preamp vs passive monitor controllers

Postby Forum Admin » Thu Mar 08, 2018 6:01 pm

Hugh Robjohns wrote:
...but I'd still go for one of the Drawmer actives. The tech specs are top-notch excellent and the performance isn't dependent on what it's connected to, or how long the cables are.

Drat! More GAS... just re-read your review, Hugh, and now I'm going to have to get one. Couldn't see it mentioned in the review but does the CMC2 have a stepped Volume knob?

And it lets you check the mono sum on a dedicated speaker, check channel phasing, and listen to the Stereo-Difference signal, all at the touch of a button -- things I genuinely couldn't work without! The M-Patch can't do any of those things....

True... it would be nice. I currently botch a workaround using one of the Studio 192 outs to feed a mono speaker and a dedicated Bus set to mono in Studio One DAW, which feeds that output.

But the CMC2 sounds perfect for my needs. Anyone wanna buy my M-Patch2?
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Re: Hifi preamp vs passive monitor controllers

Postby Forum Admin » Thu Mar 08, 2018 6:24 pm

Hmmm... one odd thing on the CMC2 is that its Dim button does not dim the main stereo outs -- it only works on the Headphones.

"The polarity, mono and dim buttons all affect the headphone output, but not the mute or the main volume control. There are pros and cons for this arrangement. For example, you’re able to mute the main speakers but use the headphones while recording, but you have to unplug or turn down the headphones when using the main monitors — but there’s no perfect arrangement for all situations, and overall I found this configuration works well enough for me."

I find this strange, because 99% of your usage of the Dim button would be to dim surely the main speakers when the phone rings, or someone steps into your studio, or you are playing a session to familiarise yourself with the song and don't want it to be your main focus whilst you do some paperwork, restring a guitar, set up a mic, etc. Yes, you can turn down the main volume, but that defeats in my mind the benefit of being able to return accurately to your chosen calibrated monitoring level.

Or am I fussing over nothing?
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Re: Hifi preamp vs passive monitor controllers

Postby Hugh Robjohns » Thu Mar 08, 2018 6:35 pm

Forum Admin wrote:Couldn't see it mentioned in the review but does the CMC2 have a stepped Volume knob?

To be honest, I can't remember... but I don't think so, no. I think it is a standard pot.

I currently botch a workaround using one of the Studio 192 outs to feed a mono speaker and a dedicated Bus set to mono in Studio One DAW, which feeds that output.

Not a bodge -- perfectly valid way of working. Most if not all of a full monitor controller's functions can be performed in the computer pretty easily these days.

But I still like a separate monitor controller for several reasons:

1. It's not reliant on the computer, so if the computer locks up or does something daft I can still mute the speakers and save my ears.

2. I can listen to other sources without needing to boot up the computer.

3. I like having a physical volume control and selection switches within easy reach.

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Re: Hifi preamp vs passive monitor controllers

Postby Hugh Robjohns » Thu Mar 08, 2018 6:38 pm

Forum Admin wrote:Hmmm... one odd thing on the CMC2 is that its Dim button does not dim the main stereo outs -- it only works on the Headphones.

I think you mis-understood, Ian. The polarity, mono and dim buttons all affect both the main and headphone outputs, but the mute and main volume controls only affect the main outputs and not the headphones.

99% of your usage of the Dim button would be to dim surely the main speakers when the phone rings, or someone steps into your studio...

Yes, and it lets you do that.

Or am I fussing over nothing?

No, I must learn to write better reviews... :-)

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Re: Hifi preamp vs passive monitor controllers

Postby Forum Admin » Thu Mar 08, 2018 6:53 pm

Thanks for clarifying Hugh. So now I'm not put off buying one. :-)

The original review is potentially misleading (I, for one, misunderstood), so if you wish to edit the article to clarify the points you made, go ahead -- that, after all, is one of the major strengths of the t'interweb; we can change things and nobody need ever know (except the sites like Wayback that archive the original web-published version; useful when you wish to locate the original version of the NASA website prior to them removing the video footage of 'sound' on the Moon... and other uses). ;)
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Re: Hifi preamp vs passive monitor controllers

Postby Matt Houghton » Thu Mar 08, 2018 8:06 pm

Forum Admin wrote:Matt, Mike didn't review it -- it was Paul White

Sorry, my bad. Though... I sense the smirking work of a sub-editor in there too :thumbup:

I was recalling this one only the other day, when writing a (forthcoming) review of the Nob Control Nob. Don't worry. I resisted the temptation...
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Re: Hifi preamp vs passive monitor controllers

Postby Forum Admin » Thu Mar 08, 2018 8:19 pm

No problemo.

Glad their new versions are getting some attention. Look forward to reading it. Is it in April issue?
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