Timeline of the SCM 50

[Mariner]

Does anyone know if there is a timeline of the SCM50 with all their changes in units and amps over the time since their first appearance?
And if there is none, isn't it a interesting task for us to use our swarm knowledge to make such a timeline?

[darrenyeats]

I think these are the two most recent changes:

• 2015 - new in-house S-spec tweeter introduced http://atcloudspeakers.co.uk/2015/06...-spec-tweeter/
• Phased in "mid-noughties" - Mk 4 amps in the Pro/Classic/Tower models

[Mariner]

Hi darrenyeats,
Thanks a lot for the first dates of the SCM50!
Do you know if there is a exact year for the amp pack change.
Do you think that the change from non SL bass unit to the ASL might be not that important than the HT-unit change?
Was there a change in the legendary mid-unit over the whole time?

[darrenyeats]

Hi Mariner, I don't have a more accurate date for the amp. Note some domestic models sold into Europe like FF anyway have the "anniversary" amps, not the Mk 4.

The SL is worth having.

Tweeter, depends where you start. If you have the previous unit (SEAS) and it has had a kind life, then the ferrofluid will not have dried and the difference will be smaller. If it's had hard use, then that's different. Sorry for being vague!

For specific info, e.g. if you have serial numbers, contact ATC by phone or Facebook Messenger (I would avoid email).

[AlastairH]

Hi both,

Also have a look at the website here

http://atcloudspeakers.co.uk/about-atc/timeline/

I forget at times just how long the 50s have been around, 1985!

[Mariner]

Thanks a lot Alastair !!!!
That´s exactly what i´m looking for !

[Mariner]

I have tried to extract the SCM50 dates from the ATC timeline
and that is what i have found:

1985 - Creation of the SCM50A because of an request from the danish radio for a compact high performance loudspeaker
1992 - Upgrade to the MK11 ampack
1996 - Upgrade to the SL ( super linear magnetic material) version. Now named SCM50ASL
2005 - ATC launched a anniversary tower version SCM50ATSL
2013 - Upgrade to the new ATC (SH25S) tweeter
2016 - Lauching of a SE Version of the SCM50ASL

What i asked myself... i think i have heard of a revision of the 3" soft dome mid unit during the timeline.
Or am i wrong ?
And i can´t find the date of the upgrade to the MK4 amp from which darrenyeats is writing!
So maybe there is a further need of completing or improving the timeline!

[AlastairH]

I have tried to extract the SCM50 dates from the ATC timeline
and that is what i have found:

1985 - Creation of the SCM50A because of an request from the danish radio for a compact high performance loudspeaker
1992 - Upgrade to the MK11 ampack
1996 - Upgrade to the SL ( super linear magnetic material) version. Now named SCM50ASL
2005 - ATC launched a anniversary tower version SCM50ATSL
2013 - Upgrade to the new ATC (SH25S) tweeter
2016 - Lauching of a SE Version of the SCM50ASL

What i asked myself... i think i have heard of a revision of the 3" soft dome mid unit during the timeline.
Or am i wrong ?
And i can´t find the date of the upgrade to the MK4 amp from which darrenyeats is writing!
So maybe there is a further need of completing or improving the timeline!

Hi,

I think it is a case of following up on Facebook or similar on the ATC group page. Ben has been there a bit and if the questions are short and simple, he should get back.

I am not sure on the two questions, my active centre has a Mk 4 amp pack from 2013. When my 100s went for servicing they definitely coated the mid domes differently. The original ones (from the mid 90s) had more of a matte looking finish, newer ones today tend to look more shiny. As to the real technical differences over the last 35 years, that really is a direct question to ATC.

[Antifon]

Just to add a little more info, this is what Pete at ATC told me a few months ago:

07/10/1987 first active version with Mk1 amppack and Audax tweeter "standard" middome, and 9" studio bass driver
1988/1989 Vifa tweeter introduced
10/05/1991 first "super" middome fitted
13/11/1991 Mk2 amppacks introduced
09/04/1992 Mk2 amppacks start to be installed
04/11/1996 introduction of Pro series
1998 introduction of SEAS tweeter
10/12/1996 introduction of SL bassdriver.
27/06/2001 Mk4 Proamp introduced
02/07/2014 introduction of ATC tweeter

Amppack board date markings:

Mk1: 01/12/85 01/12/1985
Mk2: 08 920217 17/02/1992
Mk2: 09 920929 29/09/1992 (LP filter option on vero terminal pins)
Mk3: 10 960717 17/09/1996 pro and Hifi versions built.
Mk4: 11 020501 02/05/2001 (fixed bias) (shortlived!)
Mk4: 12 020501 02/05/2001 (no filter option jumpers on BP filter)
Mk4: 13 020501 02/05/2001 (filter option jumpers on BP filter) August 2005 onwards

He did also point out that there were a lot of "specials" and custom jobs, and a fair bit of overlap during the changes - plus the Mk1 packs were made for Wilmslow for a long time after they stopped being used in their own production.

There are quite a lot of small differences between his view and the timeline higher up in the thread, but that's quite likely because of the delay from original design to the unit going into full production, I would think.

[Mariner]

Perfect Antifon !!!
Thanks a lot for that informations.

[AlastairH]

Also to note on the today’s interview with Terry and Ben on YouTube, there is an image of the SCM50 timeline, in a word document. I was listening/watching on my phone so it was not so easy to tell just how detailed this is, compared to the above comments.

[jophill]

Also to note on the today’s interview with Terry and Ben on YouTube, there is an image of the SCM50 timeline, in a word document. I was listening/watching on my phone so it was not so easy to tell just how detailed this is, compared to the above comments.

Here is a transcription of the document displayed on the YouTube video (any errors are mine):

1977/78 – S50 launched, the first 3-way ATC using a 9” bass driver in combination with the 3” ATC Soft Dome.

1985 – 3-way ATC active amp pack developed.

1987 - Gramophone Magazine reviews the SCM50A (later to become a Gramophone Magazine all-time audio classic). This review was ATC’s true entry into the hi-fi market.

1991/2 – SCM50 I updated with the SM75-150S ‘Superdome’, a revised version of ATC 3” mid-range dome employing a larger motor assembly. The results were higher efficiency, extended high frequency response and lower distortion over its operating band.

1992 - ATC develops the MK11 Amp Pack in which the output devices in the midrange amplifier were doubled, thus reducing the distortion floor by 6 dB. The ICs were changed from TL072s to NE5532s and 5534s also improving performance. These enhancements are incorporated into the active SCM range, including the SCM50.

1996 - ATC develops a new magnet design for the reduction of harmonic distortion generated in loudspeaker magnets by incorporating a “super linear magnetic material” This technology is incorporated into the SCM50 (and other models) and reduces harmonic distortion by between 12-15 dB in the lower midrange region. The port is also revised to include a flared opening for lower port noise and distortion.

2002 – Following the release of the SCM70 in 1999, the tweeter used in the SCM50 is upgraded from the Vifa D27 to a newer part manufactured by Seas in Norway. The updated part features lower distortion and an extended high frequency response.

2005 – To celebrate 30 years in business, ATC launch the SCM50 Anniversary tower. This limited edition model features exotic veneers, polished metal inlay, high-gloss lacquer and, in active guise, the all-discrete amp pack originally developed for the SCM70.

2006 – SCM50 Tower launces as a standard model. The new cabinet design extends to the floor to provide a cleaner, more modern aesthetic. The “Classic” stand mount SCM50 continues to be available.

2013 – ATC launches the eagerly-awaited SH75-76S S-Spec tweeter and the SCM50 is updated with the new component.

2014 - S50 30-way loudspeaker celebrating the company’s 40th anniversary is launched. Production is strictly limited to ten exclusive pairs.

2016 – SCM50SE is launched, featuring a new curved cabinet design inspired by Jakob Bengel and the Art-Deco movement. Cabinet construction is also improved by using multiple layers of material, laminated together.

BSL. 5^th Sept 2016.

There are some differences (e.g. the Seas tweeter date - but maybe it was introduced into the SCM70 in 1998 as per Antifon's list from Pete at ATC, and the SCM50 at the later date here).

[Mariner]

I would say .... mission completed successfully. Many thanks to all who have helped!

[Antifon]

Certainly a few minor mismatches between the different accounts, but I guess in such a low-volume (in relative terms) environment it's not unusual.

One of the things that is surprising is that the SCM70 appears twice in that last version - odd because it was such a short-lived model. I've never seen a pair, and in fact the only reason I know what they look like is because a scammer regularly advertises a pair on Ebay!

[jophill]

One thing I might add just for the record is a comment on serial numbers.

I see in the February 2020 WHF article "The making of: ATC SCM50" that Ben Lilly is quoted: "Ben reckons that since their 1985 introduction, around 3,500 pairs of SCM50s have been made to order". So I assume that's serial numbers from 1 to 7,000 at that date.

I assume also that active and passive consumer Classic and Tower models, and the active professional models share the same serial number sequence. I have seen evidence (e.g. from "For Sale" notices that quote serial number and date of production or delivery) which is consistent with that but I am not perfectly sure. I wonder if the special editions are also included. I assume so too.

That seems to be a production rate of close to 100 pairs a year.

[Mariner]

Thanks for that idea !
So you might think that a pair of SCM50 which has the serial number (for exaple) 536+537 might be from 1987, and a pair with 3652+3653 is from 1998 ?
But that will indicate that they sell 100 pairs every year! To get an "almost production year" that might be helpful, but i can´t believe that they sell the same amount of SCM50s every year. So maybe the sell only 50 pairs in 1988, but almost 300 in 1995 ?? Who knows ??
But alt last.. it might be helpful !

[Mariner]

By the way...
If i look at this offer https://www.ebay.de/itm/154387425576
jophill´s method is very precise!
SerialNr.1559+1560 and the year 1993(May) ( 8 years x 2 x 100=1600 ) fits almost perfect !

[jophill]

Adding that example to the short list I have: That's an average rate of 102 pairs per year fitting well to a constant rate. However there are significant gaps in the data. So it's plausible to estimate the date of production from the serial number but only ATC will have the real data.

[Mariner]

Respect for your effort!👍

[jophill]

Respect for your effort!👍

Thanks but it's really trivial to put a list of dates and serial numbers into a spreadsheet and ask it to draw a graph. The idea that maybe a serial number could be turned into an estimate of production date on the SCM50 timeline was yours - I was originally just thinking of numbers produced per year.