HT Units

[Mariner]

I studied the ATC webside and took pictures of the HT-units from the SCM 20 pro and classic.
At both speakers the specification says :
Pro: Drive unit – High Frequency (HF): 1”/25mm dual suspension Soft Dome (SH25-76S 6 Ohm)
Classic:Drivers: LF 6.5”/150mm SL (SB75-150SL 8 Ohm), HF 1”/25mm dual suspension Soft Dome (SH25-76S 6 Ohm)
so they seem to be the same, but at the pictures they look different ( sorry for the quality):
Pro:

Classic:


Is someone able to explain ?
Is it only the " baseplate" that is different ?
I know that there ars two different versions of the HT-unit, are these the different versions?

[Black Johnny]

I suspect the bottom pic is an old one, with the previous VIFA tweeter. The top photo is with the newer ATC-built one

[Mariner]

I have a pair of SCM20( classic) with the Vifa-tweeter, and they look more than the new pro version ( with 3 screws)
Both pictures are taken from the ATC webside today, so there is probably no old version on the pics.

[Black Johnny]

The tweeters on my Anniversary 100s look like the same as the bottom picture with four screws. Hopefully, they will shortly be upgraded to the new ones.

[Mariner]

Mmmmmmmhhhh???
So you have a 100 Anniversary with a Vifa tweeter with four scews.
There is every time something new to learn!
That means that all the pictures on the ATC website, in the CLASSIC speaker section, have pictures of speakers with the old tweeter! I never thought that!

[jophill]

My belief is that the recent ATC tweeter sequence goes:

• A Vifa tweeter with a three-screw mounting plate. Example here.
• Then a SEAS tweeter with a four-screw mounting plate. Example here comparing Vifa and SEAS.
• Now the ATC tweeter with a three-screw mounting plate (on models that can take it - not all, I think).

The ATC tweeter comes in two flavours which differ in magnet size. The "S" version has a stronger magnetic field and a higher sensitivity.

Regards
John

[Mariner]

Thanks jophill and Black Johnny for explantion!
So it seems that you are right and the pictures of the "Classic" series on the ATC website are old ones !

[SolarMusic]

The new Classic Series and Tower Series have the S-Specification Tweeter, as the Pro Series have that Tweeter.
Scm7 to 40(a) have the non S tweeter and the Scm12 pro has it (scm25 has another tweeter)

[Mariner]

Thanks for explaining, but what I ask myself....are there visual differences?
And I hoped I would find them on the ATC website.
But now it seems that they used old pictures.

[SolarMusic]

i think there is no optical difference on the front (between S an non-S), maybe for an expert
they have differt sized magnets in the back

look here, a lot infos

https://pinkfishmedia.net/forum/threads/atc-reviews-at-musicraft-derby.75474/page-13

[Mariner]

Thanks for the link!
Funny that also there in a lot of pictures the old Seas tweeter is seen.:-)

[Tobes]

Thanks jophill and Black Johnny for explantion!
So it seems that you are right and the pictures of the "Classic" series on the ATC website are old ones !

Yes, that's correct.
ATC have been pretty tardy in updating the pictures for the Classic series as the new ATC tweeter has been fitted for many years.
Maybe they think no-one looks at details like that - but clearly it does cause confusion for customers so they ought to update the pictures.

[Mariner]

That´s what ATC answered to my question:

Apologies about the confusion here. In actual fact both the SCM20 Classic and Pro use our in-house built ATC SH25-76S tweeter. I'm afraid the photo of the SCM20 Classic on our website is yet to be updated.