ATC SCM7 v.3 loudspeaker Associated Equipment

Sidebar 2: Associated Equipment

The associated equipment consisted of Parasound's Halo CD 1, used as both CD player and transport; Nordost's Silver Shadow digital cable; Bricasti's M1 DAC (since sent back); and Grace Design's full-size m905 studio Monitor Controller (the Grace m903's larger sibling, so to speak; report in thr April 2014 issue); and Cardas Clear Rev.2 interconnects and Clear speaker cables.

I did most of my listening with Lindell's AMPX class-A power amplifier. However, while the Lindell was going forth and back to John Atkinson for measuring (see January 2014, p.155), a friend dropped off a Miniwatt 2.5Wpc tubed integrated amplifier. To my surprise, the Miniwatt was able to drive the ATCs well enough to completely involve me in the music.—John Marks

ATC Loudspeaker Technology Ltd.
US distributor: Lone Mountain Audio
7340 Smoke Ranch Road, Suite A
Las Vegas, NV 89128
(702) 307-2727

Supperconductor's picture

Headline typo.

John Atkinson's picture

Thanks - JA

audiolab's picture

I know you are right in that low c on a piano is 27.5hz, I will not argue that low c on a bass guitar is 41hz (I do not know of such things), but who decided low c on an organ is 32hz. Any half decent sized organ in a cathedral or concert hall will have a 32ft stop that yields a low c of 16hz. Some people would point you to two organs in the world that have a 64ft stop that yields a low c of 8hz, some would even point out that technically one of those two could play a resultant tone of a 128ft stop resulting in a almost purely accademic low c 4hz. I am quite happy to settle with it at 16hz and what a wonderful note it is to !

John Atkinson's picture

audiolab wrote:
I will not argue that low c on a bass guitar is 41hz

The low E string (not C) on a bass guitar or double bass is tuned to 41.2Hz, but most of the energy lies an octave higher, at 82.4Hz. See fig.3 at

John Atkinson
Editor, Stereophile

jmsent's picture

In the absence of enclosure resonance as an explanation, that fairly substantial dip in the measurement between 600 and 1 kHz might be the result of a woofer "edge resonance". Surprising, given the pedigree of the company.

John Atkinson's picture

jmsent wrote:
that fairly substantial dip in the measurement between 600 and 1 kHz might be the result of a woofer "edge resonance".

I had wondered if that were the problem, but I thought that cone/surround termination problems occurred a little higher in frequency, between 1kHz and 3kHz.

John Atkinson

Editor, Stereophile

jmsent's picture

I would normally take place a bit higher up in frequency on a driver this size. But certain cone/surround combinations can push it down. But whatever the cause, that sharp dip is fairly severe, and I'm still surprised they'd let it go to market with this flaw.

RoryB's picture

Looking at the magnitude of the peak/dip couplet, which does look like a surround resonance (probably due to the relatively wide surround; a Klippel scanning laser vibrometer could reveal the true cause), it is visible in the graph but at +3/-3dB in magnitude, it is not terribly severe. At the lower frequency where it occurs, you are less likely to notice it. You might notice it more as a coloration if it occurred at 2-3 kHz, and more would need to be done to correct it. A thicker surround or a variable thickness surround could correct this problem, but it would reduce broadband sensitivity of the driver.

Bob Loblaw's picture

In the article the term active and powered to describe speakers with built-in amplification is used interchangably. They are not the same thing. An active speaker has an active crossover and 1 amplifier for each driver, such as with ATC's active speakers.

A powered speaker is a passive speaker with an amplifier built in. The Audioengine A5+ is a powered passive speaker.

Active speakers have several advantages over passive and powered passive speakers and it's a disservice to your readership not to acknowledge the difference when there are those out there who may not know better.

ryder's picture

I am well aware that small monitors cannot go too loud or too deep in the bass. Having said that, can this SCM7 v3 go loud without losing control at moderate to high volume levels? Can it go louder than say the Harbeth P3ESR?