technical question using SCM40A with 'pro' audio interface

ATC & other manufacturers design parameters, technical queries etc
Posts: 4
Joined: Mon Jan 06, 2020 10:54 pm

technical question using SCM40A with 'pro' audio interface

Postby TomCallens » Tue Jan 07, 2020 7:34 pm

Hello and greetings,

I am hoping somebody here could help me. I've sent this query also to ATC customer service but might as well try here.

I am a happy owner of a couple of second hand SCM40A's and have been driving them for a few months with a studio audio interface from Audient the id44.

I wasn't aware that I might have partnered the 40A's wrongly with a product that might have a too 'hot' output as it comes from the studio world. I thought the 40A's can be fed like any other studio active speakers (such as with the SCM50ASL's which are used in a studio of friends of mine), but perhaps I am wrong in supposing this as they are marketed in ATC's hifi line?
Am I thinking correct by supposing the SCM40A's are a 'consumer' product so should be driven with the consumer line level -10dBV and not +4dBu?

Might I hear a different sound if I would change to consumer preamp? Thus far I'm not hearing anything strange, perhaps overall a bit lack of bass/lo-mid and a bit too much high-mids. It can be quite fatiguing when listening at a louder level.

I'm confused when reading the specifications of both the SCM40's (input sensitivity 1V) and my audio interface. Could you perhaps have a look at the specs of the Audient id44?
It says maximum output level +18dBu

Audient id44:
DAC OUTPUTS (1-4):(measured from optical input under AES-17)
MAXIMUM OUTPUT LEVEL: +18dBu
DIGITAL REFERENCE LEVEL: 0dBFS = +18dBu
OUTPUT IMPEDANCE: <100Ω Balanced
FREQUENCY RESPONSE: +/-0.5dB 10Hz to Fs/2
CROSSTALK: -118dBu @ 1kHz & 10kHz
THD+N @ -1dBFS (1kHz): <0.0006% (-104dB)
DYNAMIC RANGE: 126dB A-weighted
1/4” JACK: TIP (Hot), RING (Cold) & SLEEVE (Shield)

I know this interface is in fact not good enough for these speakers but it was a temporal solution until I can muster the funds to buy better preamp/dac.

Many thanks in advance,
Tom Callens

Posts: 475
Joined: Wed Dec 21, 2011 7:01 pm
Location: Las Vegas, Nevada, USA

Re: technical question using SCM40A with 'pro' audio interface

Postby Brad Lunde » Tue Jan 07, 2020 10:00 pm

There is no reason the active 40s won't work with your Audient interface. The 40s are like a 25 with a sealed bass instead of ported bass, the new ATC tweeter instead of an VIFA model. I like the 40s for home better than the 25s. That's what I have myself.

Brad
Brad Lunde
Lone Mountain Audio, part of TransAudio Group
ATC Importers USA

Posts: 4
Joined: Mon Jan 06, 2020 10:54 pm

Re: technical question using SCM40A with 'pro' audio interface

Postby TomCallens » Tue Jan 07, 2020 10:54 pm

Hey thanks for your answer. So you are sure that electrically there's nothing wrong going on (I'm unsure how to interpet the specs of both products)?
The sound is right in many aspects but sometimes I doubt if there's not a bit too much high-mid slight harshness.
This is a quality of the speakers/preamp combo and not a mismatching?
thanks
Tom

Posts: 308
Joined: Sat Nov 30, 2013 2:29 pm

Re: technical question using SCM40A with 'pro' audio interface

Postby darrenyeats » Tue Jan 07, 2020 11:03 pm

What's the room like and what's the speaker and listener positioning? This is usually where there's an opportunity to make the biggest difference.

Posts: 4
Joined: Mon Jan 06, 2020 10:54 pm

Re: technical question using SCM40A with 'pro' audio interface

Postby TomCallens » Wed Jan 08, 2020 1:31 am

speakers/listening position in equilateral triangle, distance between speakers about 3m (10ft)
Room is a mezzanine appartment divided assymmetrically under a reversed V-roof,
speakers are under one side of the V-roof standing about 1m (3ft) from the wall, playing in the length of this side of the apartment which is 7m (23ft), to the left of L speaker is the vinyl record collection and wall about 3ft away, to the right of R speaker is no wall but a lower level part of the apartment.
Floor is wooden planks, there's wood everywhere be it piano, closet, stairs, bureau etc. Carpet, plants, couch..
It sounds fairly dry here and not bass heavy. I am mostly happy with the setup but want to make sure I'm not unintentionally coloring the experience with bad connections.
Could it be that the wood/reflections makes the sound go a bit harsher in upper mid range?

Posts: 87
Joined: Tue Sep 11, 2012 2:07 pm

Re: technical question using SCM40A with 'pro' audio interface

Postby tw99 » Wed Jan 08, 2020 12:21 pm

TomCallens wrote:Could it be that the wood/reflections makes the sound go a bit harsher in upper mid range?


I would say so. Try buying some rugs...
NACD3.5 | SBT / DSpeaker anti-mode 2.0 / SIA2-150 / SCM40 + C1

Posts: 4
Joined: Mon Jan 06, 2020 10:54 pm

Re: technical question using SCM40A with 'pro' audio interface

Postby TomCallens » Wed Jan 08, 2020 12:43 pm

I've got a reply from ATC customer service by Charlie Slee, Analogue Design Engineer,
and am posting this here for people who could have a similar question:

"Hello Tom,

You should not have any issues using your SCM40As with the id44. To drive the speakers full input sensitivity will only take 2.2dBu so you may not want to go over -18dB on your controller, bear in mind that the SCM40A have limiters so any level over 2.2dBu will be driving the amplifiers into clipping.

I believe that a lot of interfaces like the id44 have the option to change the output level via software, so you may be able to set your dBFS to 0dBu internally, and then use the full scale of your LED VU – however it is not clear from the id44 manual if this is possible."

Return to Technical area

Who is online

Users browsing this forum: No registered users and 1 guest