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ATC active monitors, are you using a pre amp? Monitor Controllers
Old 19th February 2012
  #1
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tun's Avatar
ATC active monitors, are you using a pre amp?

Guys,
I've been using my SCM50ASL Pro with SH Equinox, however the general consensus on the UK hi-fi boards seems to be that ATC's SCA2 pre amp is needed to get the best out of the large ATC actives. I considered the SCA2 to be hi-fi gear so thought it unsuitable for pro applications, however the UK ATC dealer has already advised me that a passive pre will not get the best out of the active 50's or 100's, so this leads me to asking what pre amp (if any) studios are using with these speakers. I'm really interested what pro guys are using with their 50's or 100's and would be very grateful for any input.
Old 19th February 2012
  #2
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Actives do not need a pre amp full stop. That is the point of being active
Old 19th February 2012
  #3
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Marcocet's Avatar
For studio duties I don't see what good a preamp would do, assuming you're happy with your monitor control situation.
Old 20th February 2012
  #4
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Fleaman's Avatar
 

Quote:
Originally Posted by tun View Post
Guys,
I've been using my SCM50ASL Pro with SH Equinox, however the general consensus on the UK hi-fi boards seems to be that ATC's SCA2 pre amp is needed to get the best out of the large ATC actives.
I don't own an ATC, but a few observations:

I think the SCM50ASL has ONLY a XLR balanced input, correct? Perhaps this is also a +4 input? All consumer gear is unbalanced -10 levels, so it wouldn't interface well with this speaker, with the exception of some higher level hifi stuff that does have a fully balanced +4 output.

This would be the reason a 'hi-fi forum' would mentioned that the SCA2 pre-amp should be used with this monitor (and I would agree, if being used with unbalanced -10 consumer gear).
Old 20th February 2012
  #5
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I find it more a question of philosophy. Why would you want to add extra coloration with more circuitry at the monitoring stage? Adding a preamp will only make the monitors less accurate. In the HiFi world, things are a bit different in that people are in search of a more euphonic listening experience which explains some of the equipment choices (tube amplifiers, preamps, etc.). However, since that circuitry is not being applied to the actual recording you're making, it makes little sense to color your monitor path further .

That being said however, there are definitely exceptions. I do know of engineers making specific monitoring choices as to their listening preference (like power amplifiers for example) but usually it's out of habit and familiarity, or in the case of NS-10s, being able to listen to them for more than 5 minutes without stabbing yourself in the ear.
Old 20th February 2012
  #6
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Fleaman's Avatar
 

Quote:
Originally Posted by nlc201 View Post
Adding a preamp will only make the monitors less accurate. In the HiFi world, things are a bit different in that people are in search of a more euphonic listening experience which explains some of the equipment choices (tube amplifiers, preamps, etc.).
A 'preamp' in the hifi world is a different animal than a preamp in the pro world.

'preamp' in consumer hifi is just a line level device with volume control. For most things connected to it (CD player, tape player, etc.), it's really just acting as volume control. The only thing it would actually 'pre-amplify' would be the phono cartridge.

'preamp' in the pro world is essentially a mic amplifier, to bring a mic level signal up to line level.

The OP was talking about a consumer preamp to pre-amplify a consumer line level (-4) to a pro balanced level (+10) that the ATC monitors in question ideally would want to see.
Old 20th February 2012
  #7
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Quote:
Originally Posted by tun View Post
Guys,
I've been using my SCM50ASL Pro with SH Equinox, however the general consensus on the UK hi-fi boards seems to be that ATC's SCA2 pre amp is needed to get the best out of the large ATC actives. I considered the SCA2 to be hi-fi gear so thought it unsuitable for pro applications, however the UK ATC dealer has already advised me that a passive pre will not get the best out of the active 50's or 100's, so this leads me to asking what pre amp (if any) studios are using with these speakers. I'm really interested what pro guys are using with their 50's or 100's and would be very grateful for any input.
hi tun
i run the 50's with a hig-hend preamp. it improves everything! liveness, 3d imaging, transparence, transients... but of course, it has to be a very good pre.
try "mark levinson" pre's for example and just listen you will be surprised!

michael
Old 20th February 2012
  #8
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tun's Avatar
Thanks for your replies guys.

Since posting this topic I've learned that ATC's acronym 'SCA' actually stands for 'studio control amp'.

I'm well aware of colouration issues regarding hi-fi gear, however I'm not sure the ATC SCA2 falls into this category.

Tbh, I find the sound of the speakers a bit 'lacklustre' on some material, just using the (passive) monitor controller section of the Equinox.

I'm inclined to agree with Michael's observations regarding how a high quality pre amp can improve the sound (and of course I'm not talking about mic pres) of an active monitoring system.

The ATC actives have balanced XLR ins only, so for the monitoring chain I'm thinking as follows:
DA>SH Equinox monitor out or main 2 buss out>ATC SCA2 aux in (balanced XLR)>SCM50ASL Pro

The ATC SCA2 also comes with an optional (very good quality) phono stage, which for me would be killing 2 birds with 1 stone.
Old 20th February 2012
  #9
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Fleaman's Avatar
 

Quote:
Originally Posted by tun View Post
The ATC actives have balanced XLR ins only, so for the monitoring chain I'm thinking as follows:
DA>SH Equinox monitor out or main 2 buss out>ATC SCA2 aux in (balanced XLR)>SCM50ASL Pro
Are you using these monitors in a hifi setup or studio set up? Sounds like a studio...what's your main 2 buss?

The Equinox should be a very hi-end line level pre-amp (as good or better than the SCA2) IF you're using the correct inputs, which would be the external inputs or the DAW 1-2 in's (I don't think there's a circuit difference between them?).

It's shouldn't matter that the line level pre is passive or active as long as you are getting enough level into the monitors. In fact, in theory a high end passive pre (like the equinox--using the correct inputs) should be better than an active pre (again, assuming you have a +4 level going into the passive pre in the first place). IF you're DA isn't outputting +4 balanced, then that is what I would be looking at.
Old 23rd February 2012
  #10
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tun's Avatar
Quote:
Originally Posted by Fleaman View Post
Are you using these monitors in a hifi setup or studio set up? Sounds like a studio...what's your main 2 buss?

The Equinox should be a very hi-end line level pre-amp (as good or better than the SCA2) IF you're using the correct inputs, which would be the external inputs or the DAW 1-2 in's (I don't think there's a circuit difference between them?).

It's shouldn't matter that the line level pre is passive or active as long as you are getting enough level into the monitors. In fact, in theory a high end passive pre (like the equinox--using the correct inputs) should be better than an active pre (again, assuming you have a +4 level going into the passive pre in the first place). IF you're DA isn't outputting +4 balanced, then that is what I would be looking at.
Hi Fleaman,

It's a studio setup and my D/A is +4 going into the Equinox. I'm not enquiring about the active ATC pre because I'm using consumer gear. My question is solely about getting the best sound out of the speakers.

Whether for studio use or not, I've been advised that the SCA2 was made by ATC to be the perfect partner for the large ATC actives. The UK ATC dealer has said on numerous occasions that an active pre (ie: the SCA2) is essential to get the very best out of the speakers. According to him, a passive pre (like the Equinox) will not. His opinion is echoed by many others over on the UK ATC forum.

However, I realise that most of the guys dishing out advice are hi-fi enthusiasts, with little understanding of pro monitoring requirements, so that's why I'd really like to know what pro studios are using with their large ATC actives such as the SCM50ASL, SCM100ASL, SCM150ASL etc.

Just a few examples... Doug Sax, Gavin Lurssen, Abbey Road, Kaiser Sound, Blackbird Studio (Nashville), Great Divide Studios (Aspen), British Grove Studios, all using ATC. I'd love to know whether they're using the SCA2 in the studio.

Cheers
Old 23rd February 2012
  #11
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Fleaman's Avatar
 

Quote:
Originally Posted by tun View Post
Hi Fleaman,

It's a studio setup and my D/A is +4 going into the Equinox. I'm not enquiring about the active ATC pre because I'm using consumer gear. My question is solely about getting the best sound out of the speakers.
Ok, sounds like you're setup is good, assuming you're using the correct inputs on the Equinox (i.e. NOT the mic pre inputs), and you have all the tranny options bypassed, etc.

Quote:
Whether for studio use or not, I've been advised that the SCA2 was made by ATC to be the perfect partner for the large ATC actives. The UK ATC dealer has said on numerous occasions that an active pre (ie: the SCA2) is essential to get the very best out of the speakers. According to him, a passive pre (like the Equinox) will not. His opinion is echoed by many others over on the UK ATC forum.
I don't understand the logic or reasoning behind this. Unless I'm missing something, it sounds like BS. Ask him to technically explain the reasoning behind this? And post it here.
As I mentioned, as long as you're getting a good balanced level into the active ATC monitor, and there's no strange impedance mismatch, it shouldn't matter if you have an active or passive pre, in fact, IF you're getting a good level into the monitors (which you should with a +4 input into the Equinox), as passive pre is theoretically better than an active pre.

In fact, hi-fi enthusiasts actually will use a passive attenuator (resister based) between a CD player and a power amp (or active monitor) over an active pre amp due to the minimal amount of electronics in the pathway. Like these: Goldpoint Level Controls

Quote:
However, I realise that most of the guys dishing out advice are hi-fi enthusiasts, with little understanding of pro monitoring requirements
Yes, as I mentioned, this is the most likely reason. A +4 balanced input of the active ATC monitor isn't normal in the hifi world. Since most hifi gear is -10 unbalanced, an active pre IS needed to interface with a +4 balanced ATC monitor.

So, ask whoever advised you to get the 'active pre' to explain how it is superior over a passive pre when you can already output +4 balanced from your passive pre.

I would also call shadow hills and ask them if there is any difference between the 'external inputs' and the '1-2 daw' inputs circuit wise. And which would be the cleanest (if there's a difference). Tell them how you're using the unit and see what they say. You can also ask them about the 'active pre' theory posed by the hifi ATC dealer.
Old 24th February 2012
  #12
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tun's Avatar
Thanks Fleaman, will post my findings.
Old 24th February 2012
  #13
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Quote:
Originally Posted by tun View Post
Hi Fleaman,

It's a studio setup and my D/A is +4 going into the Equinox. I'm not enquiring about the active ATC pre because I'm using consumer gear. My question is solely about getting the best sound out of the speakers.

Whether for studio use or not, I've been advised that the SCA2 was made by ATC to be the perfect partner for the large ATC actives. The UK ATC dealer has said on numerous occasions that an active pre (ie: the SCA2) is essential to get the very best out of the speakers. According to him, a passive pre (like the Equinox) will not. His opinion is echoed by many others over on the UK ATC forum.

However, I realise that most of the guys dishing out advice are hi-fi enthusiasts, with little understanding of pro monitoring requirements, so that's why I'd really like to know what pro studios are using with their large ATC actives such as the SCM50ASL, SCM100ASL, SCM150ASL etc.

Just a few examples... Doug Sax, Gavin Lurssen, Abbey Road, Kaiser Sound, Blackbird Studio (Nashville), Great Divide Studios (Aspen), British Grove Studios, all using ATC. I'd love to know whether they're using the SCA2 in the studio.

Cheers
Hi Tun:
I have supplied the speakers to most of the folks you mention above, the US ones anyway. I think you are confusing pro and consumer worlds. ATC builds a preamp for hi fi customers, who need a preamp as place to select and control multiple sources. ATC does not need to build a preamp for pro, pro customers feed the speakers from only a few sources, sources they control through a console for example. So the point that ATC builds a preamp to get the most of your ATC speakers addresses the fact that most consumer preamp sources are not so great, and the ATC SCA2 is very good. If the preamps are poor, it ruins sources before they ever get to the speakers.

This addresses your question, yes?
Brad
Old 8th October 2013
  #14
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Crazy Drummer69's Avatar
 

Quote:
Originally Posted by nlc201 View Post
I do know of engineers making specific monitoring choices as to their listening preference (like power amplifiers for example) but usually it's out of habit and familiarity, or in the case of NS-10s, being able to listen to them for more than 5 minutes without stabbing yourself in the ear.
I LOLed so hard at this that I just had to comment (researching ATC SCM150ASL)
Old 8th October 2013
  #15
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Steve Honest's Avatar
 

HAd a pre went back

Hi
I have 2 pairs of active 100slm s and one pair i bought came with a pre, the ATC one.

Tried it, didn't like it, went back to the speakers connected to the desk in both rooms, sold the pre.
sounds amazing

steve
Old 8th October 2013
  #16
This is the answer:

Quote:
Originally Posted by Brad Lunde View Post
Hi Tun:
I have supplied the speakers to most of the folks you mention above, the US ones anyway. I think you are confusing pro and consumer worlds. ATC builds a preamp for hi fi customers, who need a preamp as place to select and control multiple sources. ATC does not need to build a preamp for pro, pro customers feed the speakers from only a few sources, sources they control through a console for example. So the point that ATC builds a preamp to get the most of your ATC speakers addresses the fact that most consumer preamp sources are not so great, and the ATC SCA2 is very good. If the preamps are poor, it ruins sources before they ever get to the speakers.

This addresses your question, yes?
Brad
I have a pair of custom built 110asl's. specced for my room by ATC. No preamp. No need.
Old 7th November 2013
  #17
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tun's Avatar
Guys
I just saw the thread had been resurrected.
I stopped worrying about pre amp issues long ago and am more than happy with the Equinox & SCM50ASL Pro!
Thanks all for the input, and especially for your contribution Brad.
Old 7th November 2013
  #18
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Quote:
Originally Posted by DannyMac View Post
Actives do not need a pre amp full stop. That is the point of being active
Actually the point of being active means they don't need an AMP. They will still need some sort of preamp or attenuator for volume control.
Old 17th July 2014
  #19
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robertopisa's Avatar
Impedance problem

Quote:
Originally Posted by Fleaman View Post
...
As I mentioned, as long as you're getting a good balanced level into the active ATC monitor, and there's no strange impedance mismatch, it shouldn't matter if you have an active or passive pre, in fact, IF you're getting a good level into the monitors (which you should with a +4 input into the Equinox), as passive pre is theoretically better than an active pre.

In fact, hi-fi enthusiasts actually will use a passive attenuator (resister based) between a CD player and a power amp (or active monitor) over an active pre amp due to the minimal amount of electronics in the pathway. Like these: Goldpoint Level Controls


Yes, as I mentioned, this is the most likely reason. A +4 balanced input of the active ATC monitor isn't normal in the hifi world. Since most hifi gear is -10 unbalanced, an active pre IS needed to interface with a +4 balanced ATC monitor.

So, ask whoever advised you to get the 'active pre' to explain how it is superior over a passive pre when you can already output +4 balanced from your passive pre.
...


I revived this 3d to emphasize the impedance mismatch problem when using a passive volume control.

I tried to connect directly my Forssell DAC (5 ohm balanced output impedance) to the ATC SCM50ASL (10 kohm balanced input impedance) using a passive volume control (whose impedance can be regulated to 5 - 10 - 20 - 50 kohm).

Well, the sound is somehow better but at the price of loosing dynamics and punch. It is better to add an active output buffer to lower the impedance of the volume control to 10 - 20 ohms. I think an output transformer of 600 ohm cannot exploit the ATC SCM50ASLs at their best as the active output better does. Some transparency is lost but greater dynamics is obtained.

Lesson learned: I am not aware of any passive volume control with a good impedance match for ATC SCM50ASL... better to use an active volume control with < 200 ohm output impedance.

Last edited by robertopisa; 17th July 2014 at 03:30 PM.. Reason: Quoted a previous post
Old 17th July 2014
  #20
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Hi
Eventually, hopefully before hell freezes over, people will learn that a PASSIVE preamp (apart from being technically incorrect terminology) is a BAD idea.
If you wish to connect any pieces of gear with cables longer than a few metres, then there should be an AMPLIFIER 'driving the signal into the cable.
The root of the problem is a technical impossibility to have a LOW impedance 'attenuator' that does not heavily load the output stage of the signal you are monitoring.
Most 'pro' gear will be happy 'driving' a load down to say 600 Ohms (historical throwback) however for best 'fidelity' when driving a cable it should really be a lower impedance than that, say 50 Ohms as a reasonable, practical estimate. Very few pieces of gear can manage to 'drive' this low an impedance.
If gear COULD manage to 'drive' say 50 Ohms then a 50 Ohm Goldpoint attenuator would be a good choice of 'passive' preamp as variation in frequency response would be minimal. Notice I say 50 Ohms and not 50K Ohms which is obviously a thousand times higher resistance and would be a VERY inferior control UNLESS it has an AMPLIFIER stage connected with a few centimetres (inches) of wire ONLY. The variation in frequency response with differing PASSIVE control positions is due to the fact the 'sending' impedance changes depending on the setting of the control with the 'worst' position being 6dB 'down'. Thus in effect as you approach the '-6dB' position you may effectively be introducing HF 'cut'
Regarding the issue of balanced or unbalanced. The QUALITY of the required signal can and usually is, THE SAME whether balanced or unbalanced. What is different is that a balanced connection usually ensures that unwanted HUM does not intrude. A balanced connection might also help keep interference out.
As long as your setup does not suffer from HUM or interference then a balanced or unbalanced signal should be identical.
Matt S
Old 17th July 2014
  #21
Gear Nut
 

I have SCM-50 ASL's in a listening room. Various sources to a PASS preamp (XLRs). When PASS didn't a service on the pre-amp the improvement was substantial (and prior to that the sound was excellent....) so don't overlook your monitor controller, volume pot (quality), or preamp. ATCs tell the story.
Old 17th July 2014
  #22
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robertopisa's Avatar
@Matt S.: Is the output impedance of volume control in desks low in the order of few ohms? Are output buffers or trafos employed there?

@leadpalyer: sorry, I did not get what you want to say... are you referring to Nelson Pass' B1? In that case, it has an (active?) output buffer even if the rest is passive.
Old 18th July 2014
  #23
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Hi
Yes there is almost always an output amplifier following the volume pot. This is physically close to the pot in 'good' designs.
Transformers are a different aspect altogether, but you would not use a transformer directly on a pot to provide an OUTPUT circuit. I suppose you could, but it would need to be 20dB step DOWN to make the impedance change worthwhile so severely limiting output capability.
Matt S
Old 18th July 2014
  #24
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robertopisa's Avatar
Thanks, this is good to know as I am following that path.
-R

Quote:
Originally Posted by Matt Syson View Post
Hi
Yes there is almost always an output amplifier following the volume pot. This is physically close to the pot in 'good' designs.
Transformers are a different aspect altogether, but you would not use a transformer directly on a pot to provide an OUTPUT circuit. I suppose you could, but it would need to be 20dB step DOWN to make the impedance change worthwhile so severely limiting output capability.
Matt S
Old 18th July 2014
  #25
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Hi
The conundrum surrounding a passive attenuator/pot while feeding cables to an active monitor/power amp while retaining maximum fidelity is something akin to wanting a sports car that will travel at 150 miles per hour but expecting it to do that with only 1 gallon of fuel to travel all 150 miles. Nice idea but can't be done.
Matt S
Old 18th July 2014
  #26
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robertopisa's Avatar
Well I have the gallon of fuel but not yet the sport car
-R

Quote:
Originally Posted by Matt Syson View Post
Hi
The conundrum surrounding a passive attenuator/pot while feeding cables to an active monitor/power amp while retaining maximum fidelity is something akin to wanting a sports car that will travel at 150 miles per hour but expecting it to do that with only 1 gallon of fuel to travel all 150 miles. Nice idea but can't be done.
Matt S
Old 12th November 2015
  #27
Reviving this thread...here I am with my old ATC SCM50A at full volume and my TC Konnekt 48 DIGITALLY LOWERING THE VOLUME before sending it to spdif and my DAD 2402. I was using it at VERY low digital level, multiple digital faders down, to keep the SCM to be too loud...and I just read it's not good, and there is loss.

So I just plugged my Revox C279 board with full digital volumes up, and the console doing the reduction. I might have gained dynamics or space, it seems. but it's supposed to be 5ohms and I also heard very different and roll off highs, or compressed.

Is there an ideal impédance matching the SCM50A inputs ( mkII amps from 1992! ) ? any advice on an active box ?

EDIT: luckily I just found an old ATC CA2 mki, supposed to be used with my very SCM50A, do you think it'd be a good match ??

Last edited by DownSideUp; 12th November 2015 at 01:31 AM..
Old 12th November 2015
  #28
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Sounds like you actually want a monitor controller? E.g. Crane song Avocet, Dangerous Source, New Old Sound MCOne etc.
Old 12th November 2015
  #29
I do ! but which one? you mentioned passive ones too...( i had the Big Knob and it was just a joke)


Also the ATC CA2 could do just fine as a monitor controller, but I wonder if it's the perfect match.

In the end I just need an attenuator for my ATC SCM50A, as I still have my digital remote to slightly vary the volume for working.

Last edited by DownSideUp; 12th November 2015 at 10:59 AM..
Old 12th November 2015
  #30
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I'm using a SoundSkulptor MC624 stepped-ladder attenuator. Sounds great. I can't hear any difference with it in and out of circuit, and the distortion is way lower than my converters (to the point where I can't measure any difference with Fuzz Measure).

I had a passive controller for a while - TC electronic level pilot. Works well with short cable runs as said above, but it still impacts the dynamics and soundstage depth.
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