ATC PA-65

ATC & other makes of Hi-Fi equipment
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Re: ATC PA-65

Postby MattSPL » Wed Oct 12, 2016 7:38 pm

Hi David,

I hope your neighbors have similar tastes in music :)

Cheers
Matt
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: ATC PA-65

Postby studioman » Wed Oct 12, 2016 8:54 pm

Mr. Gilmour in studio....With HIS specially modified ATC SCM150s in the background.... They probably don't have names, though....

https://s-media-cache-ak0.pinimg.com/or ... b21c10.png
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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Re: ATC PA-65

Postby Lemen » Wed Oct 12, 2016 11:48 pm

studioman wrote:Hi Lemen.

Might be able to help....

The guy who did my stainless lathe work is a guy on eBay who custom turns anything of a reasonable size. He has done a number of parts for me, and has become a 'distance' friend and work colleague.
As my strength in particular is Computer Aided Design, he can program his lathe to my specs. If you are serious about it, I don't mind doing a bit of Pro-Bono CADwork for you, then you can send him the file and deal with him direct. The outrigger bars were laser cut by a different company, and were very basic when they arrived (not drilled or given their brushed finish). Let me know, and also if you do want to think about going ahead with it, I could message you privately to tell you how much they cost.

My design on my speakers allows me to move the speakers with the outriggers fitted, using a set of four 10mm threaded castors screwed in place of the spikes, to get them finally into place, then the plan is to tip them, remove the castors and replace them with the spikes and adjusters.

Your other alternative would be to make (or have made for you) a thick base of plywood or pdf or even acrylic (much more expensive) either cut by hand or laser cut, maybe painted black, , and have the spikes and locknuts screwed into this. So you're actually making a platform which, as you say, you could slide your speakers onto. I would put some sticky back felt on top of it so the speakers don't get scratched. I could also help you design that.


Hello studioman

Thank you for your very kind offer of help with CAD. I have been watching a lot of CNC machines in action over the last few months on youtube. It's utterly "gobsmacking" to see what is achievable with these machines and I'm currently rather mesmerised by them. Of course some CAD software is shown - it's fascinating to see the design process of a part and the steps/paths that the various tools will follow.

Unfortunately, I'm currently overtaken with house maintenance duties and can't yet spend a great deal of time on the ATC's. I have designed and built my own speaker stands in the past. These were made from 10mm thick aluminium plate for the bases and 5mm for the top plates. Inbetween were two pillars of ¼ inch thick wall aluminium tubes of 2 inch diameter. They worked very well with SCM7's (which the stands were designed to suit). Cutting the 10mm plate was quite a chore but a router machines it up VERY well indeed, as long as lots of lube is used! The edge could then be finished off with sandpaper and wet sand to rub out the machining marks and to apply the "brushed" finish if desired. I even bevelled the top edge with a 45°. I could easily cut a rectangle of 10mm alum plate again to suit the 50's but I'd like to make something much more "designed" than a simple rectangular plate. I have found Track Audio http://www.trackaudio.co.uk/ who make a very nice stand and base, on which I would like to base my design. I may attempt a speculative approach to them to see if they may be willing to make a version of their base to my design. It's probable that they may not be too receptive to this approach as companies may be worried about design theft etc. Anyway, we will see.

When I have the spare time to really concentrate on the ATC's, (and the other 'alf allows) I'd like to get the base supports sorted aswell as the midrange waveguide. In the meantime, watching the progress of your build is great to see. I do like your spikes/adjusters VERY much. May I ask, have you fixed the knurled top adjuster to the thread with adhesive? It would seem that if the knurled "knob" is screwed on tightly without adhesive that it may come loose when turned anti-clockwise in situ? The knurled ring that sits below the height adjuster knob is a thin locking ring? They are a superb design and very nicely made. Thank you again for your offer of help, I may well get back to you on that :-)

Lemen
ATC SCM50 ASLT Anniversary (gloss white)

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Re: ATC PA-65

Postby studioman » Thu Oct 13, 2016 11:09 am

Hi Lemen

Thanks for the compliments!

The knurled adjusting handles and the M10x1.5 threads are all in one piece.
The spikes themselves are separate items, which the adjuster threads into.
I did wonder about aralditing but to be honest, by the time the adjusters are tightened into the spikes, they 'bottom out' and are fixed together firmly enough.
It also means I can remove the spikes when necessary from the outriggers, to replace them with castors for easy movement.

The castors I got were cheap enough, and have are M10 with a 1.5mm pitch thread.
These are known as 'coarse M10'....be careful because there is also a finer M10 thread with a 1mm pitch between the threads, and these would not be compatible.
I standardised on M10 x 1.5 throughout.

The locking rings are knurled stainless, 2mm thick. You can also see specially made nylon washers and 6mm thick pure wool felt to damp any vibration in the outriggers.

Cheers, David

Image

Image
Last edited by studioman on Sat Oct 15, 2016 5:32 pm, edited 2 times in total.
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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Re: ATC PA-65

Postby Lemen » Fri Oct 14, 2016 10:25 am

Ah, thanks for the new photos David, I see now precisely how you've produced them. As you could obviously tell, I'd wrongly assumed that the thread was machined as part of the spike. Nice to see the rounded-off edges and the brushed effect applied on the bars aswell!
Much thanks for the info on M10 thread pitch.

Lee.
ATC SCM50 ASLT Anniversary (gloss white)

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Re: ATC PA-65

Postby studioman » Sat Oct 15, 2016 5:32 pm

Lemen wrote:Ah, thanks for the new photos David, I see now precisely how you've produced them. As you could obviously tell, I'd wrongly assumed that the thread was machined as part of the spike. Nice to see the rounded-off edges and the brushed effect applied on the bars aswell!
Much thanks for the info on M10 thread pitch.

Lee.



The whole story of my DIY speakers is here (below) on Pinterest. Very worth joining for all the info on there....

https://uk.pinterest.com/TheTrike/pride-joy-my-diy-atc-loudspeaker-project-pa65-atc-/
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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Re: ATC PA-65

Postby Lemen » Thu Oct 20, 2016 12:27 pm


Ahh, highly pinteresting stuff indeed, thanks for the link. I like your cat Billie, it looks like she is good company
when you're hard at work. If ever you were to hear a strange noise emanating from one of your speakers, and
Billie could not be found :-)

What a great idea to add those loops of ribbon for easy removal of the bass drivers whilst you fine tune the
internals for best sound quality etc.

BTW, the pair of white SCM50ASLT anniversary you have saved are my very speakers - serials 141/142!
If you look carefully you can see that the dust-cap of the bass-driver of the right cabinet is damaged.
The dust-cap has been pushed in at some point and is "soft". It could be coated with Oppanol to stiffen it up
again, but it doesn't really matter as I have a new unit ready to exchange it out when I get to doing all the
other work I want to do on the speakers.

It sounds as though you are quite near to a first proper test?
ATC SCM50 ASLT Anniversary (gloss white)

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Re: ATC PA-65

Postby studioman » Sat Oct 22, 2016 8:53 pm

Lemen wrote:

Ahh, highly pinteresting stuff indeed, thanks for the link. I like your cat Billie, it looks like she is good company
when you're hard at work. If ever you were to hear a strange noise emanating from one of your speakers, and
Billie could not be found :-)

What a great idea to add those loops of ribbon for easy removal of the bass drivers whilst you fine tune the
internals for best sound quality etc.

BTW, the pair of white SCM50ASLT anniversary you have saved are my very speakers - serials 141/142!
If you look carefully you can see that the dust-cap of the bass-driver of the right cabinet is damaged.
The dust-cap has been pushed in at some point and is "soft". It could be coated with Oppanol to stiffen it up
again, but it doesn't really matter as I have a new unit ready to exchange it out when I get to doing all the
other work I want to do on the speakers.

It sounds as though you are quite near to a first proper test?


Billie appreciates the compliment and says Hi.:-)

I did think the white ones were yours - I hadn't seen white ones before! Very, very nice.

I always found that a vacuum cleaner tube worked wonders when trying to reshape dust caps! I have only heard of Opanol quite recently. I have always used PVA, slightly watered down, as a doping agent for fibre cones and fibre dust caps.

So far I have successfully tested the separate drivers in ONE speaker using a signal generator app on my iPad connected direct to one driver at a time. I then connected the AmpPack up and all was good (just briefly). I must find time in the next few days to finish rigging up and checking the second speaker out....

THEN.... they're going into the lounge to be positioned and have the spikes fitted.....Ready for Roger Waters 'The Wall' film on Bluray. I've been saving that from last Christmas for this purpose.:-)
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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Re: ATC PA-65

Postby MattSPL » Sat Oct 22, 2016 11:08 pm

That's going to be a grand christening of that disc and your speakers :D
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: ATC PA-65

Postby Lemen » Tue Oct 25, 2016 12:21 am

studioman wrote:I did think the white ones were yours - I hadn't seen white ones before! Very, very nice.

Thank you.

studioman wrote:I always found that a vacuum cleaner tube worked wonders when trying to reshape dust caps!

Yes I have found that to work very well in the past. Some 30 years ago, one of our 3 remaining Tervueren
puppies pushed in the dust-cap of one of my speakers, I was devastated at the time, especially as these were
Realistic speakers from Tandy (I've come a very long way since then!).
I had the idea to use the vacuum cleaner, starting on very weak suction, slowly increasing the suction until
it was just sufficient to pop out the dust-cap again.

The dust-cap on the 50's still has its correct convex shape but is simply soft from where it has been pushed in,
and I assume, pulled out again. It doesn't appear to affect sound quality at all. As I say, I have the new
replacement unit anyway so . . . .
Look out for the old unit on eBay . . . . eventually.

studioman wrote:THEN.... they're going into the lounge to be positioned and have the spikes fitted.....Ready for Roger Waters 'The Wall' film on Bluray. I've been saving that from last Christmas for this purpose.:-)

Wehey, should be superb. Looking forward to your thoughts.
ATC SCM50 ASLT Anniversary (gloss white)

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Re: ATC PA-65

Postby studioman » Wed Oct 26, 2016 8:28 pm

That's the trouble with a Triplicity of Tervuerens...
you know, one eggs the other ones on....
Kids, eh?!
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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Re: ATC PA-65

Postby studioman » Mon Oct 31, 2016 10:21 am

I had a fantastic boost today in a PM message that was from one of you, complimenting me on my work converting a pair of PA65s to a pair of SCM150ASLT cabs....
It really made my day. I have already thanked that particular guy!

It is so nice that folk on here generally are much more positive, accepting and encouraging than I find on other forums where I often come across posts which are argumentative, narrow minded and unsupportive, and sometimes show arrogance which is very off-putting.

Long may the ATC Forums attract decent, friendly folk.
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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Re: ATC PA-65

Postby MattSPL » Mon Oct 31, 2016 5:35 pm

Hi David,

You are right, this is a great forum full of knowledgeable, friendly people :)

ATC themselves are also a one of a kind company, happy to help ATC enthusiasts out where they can.

Cheers
Matt
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: ATC PA-65

Postby AlmaataKZ » Tue Nov 01, 2016 6:52 pm

studioman wrote:I had a fantastic boost today in a PM message that was from one of you, complimenting me on my work converting a pair of PA65s to a pair of SCM150ASLT cabs....
It really made my day. I have already thanked that particular guy!

It is so nice that folk on here generally are much more positive, accepting and encouraging than I find on other forums where I often come across posts which are argumentative, narrow minded and unsupportive, and sometimes show arrogance which is very off-putting.

Long may the ATC Forums attract decent, friendly folk.


Your project indeed is a special one. I envy your skills and thorooghness and quality.
I do not understand the rationale for the supertweeter though. Can you explain?
iMac/Bluray/PVR - Marantz SR7008 - 7.1 ATC SCM50SLAT fronts, C1C centre, SCM7 rears, MonitoAudio M3 rear surr, C4 sub
Airplay multiroom (aex to genelec 6010, b&w mm1, avi dm10)
System here: http://atcforums.co.uk/viewtopic.php?f=16&t=667

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Re: ATC PA-65

Postby studioman » Tue Nov 01, 2016 8:07 pm

Hi AlmaataKZ...

Thanks for the compliment!

Yeah....re: the super tweeter....this might be difficult but I'll try to explain my thought process....

It's like this....electrical current, synapses and ganglions, blah blah blah.....ending up with 'I think, therefore I AM a loudspeaker designer.' :lol:

OK....serious now...get tech. Here goes....

Firstly, I already had my Townshend supertweeters. I had bought them used, but in perfect condition. I used them in my Office system on top of some old Rega Xels. At first there was very little coming from them and I couldn't understand why. Then I tried the tightness of some of the external casing screws and found they were loose. I assumed therfore that the internal ones might be loose too. I dismantled them and found LOADS of play in everything. Once I had tightened everything up, they worked a treat. Lovely metallic sheen to cymbals, etc.....you could REALLY hear the breathing clearly on some close-miked voices, etc....
I also have a pair of wonderful old Celef RT-1 speakers with ATC bass units, KEF B200 used in an open backed format as a midrange, and with unbelievable Decca Ribbon Tweeters. So you can see that I am quite enamoured with a ribbon here and there. Including on thighs, but that's another story. :oops:

When I bought my PA65s, for a short while before I dismantled them for the parts, I tried the PA65s without and with the supertweeters. And they did make a small but noticeable and worthwhile difference.
I was lucky that my PA65s were in good condition, driver and amp wise, and they had been serviced and updated regularly by ATC. The drive units all had stickers on showing the dates that they had been installed, replaced, modded etc. The same went for the AmpPack.

The tweeters, I was overjoyed to find, were the new (in 2011) 'ATC made' SH34-76 models. So they were very worthwhile having.
However, if you check the spec of some of the current range of 'larger' ATC speakers, like the SCM150 ASLT, you will find the following:

SCM150SE: (with 25mm SH25-76S), Freq Response +/- 2dB is 60Hz to 17kHz, Freq Response +/- 6dB is from 25Hz to 25kHz
SCM150ASLT: (with 25mm SH25-76), Freq Response +/- 2dB is 60Hz to 17kHz, Freq Response +/- 6dB is from 25Hz to 22kHz
PA65: (with original SEAS or VIFA tweeter) Freq Response +/- 2dB is 60Hz to 12kHz, Freq Response +/- 6dB is from 25Hz to 22kHz
The difference between the original PA65's high frequency response and that of the Studio designs is largely down to the difference in the choice of tweeter. But in the case of the PA65 which was designed for nightclub use (ie high volume & high quality), the reduced range of linearity in the frequency response curve was not a major issue. In fact it was the efficiency of the tweeter that was more important in that application. Otherwise folk would believing nightclubs not only pissed and naked, but also with tinnitus.

HOWEVER.... mine had been re-fitted with the SH34-76 model tweeters in 2011. Lucky, eh? Larger domes such as a 34mm dome are known to not 'go' as high as smaller (25mm or 19mm) domes. But these were efficient and had to be reliable in a nightclub. You couldn't have tweeter domes falling out all over the place. They proved to be both efficient AND reliable, as well as having great clarity. So they were perfect for nightclub use.

When I had my amp-packs re-capped, I asked ATC's advice about setting up the levels on the amp-pack (using the internal trimmers), and was told it would be best to set up the bass for a 150 litre cabinet instead of a 65 litre one, and to set the mid and treble levels to match the bass output. So the levels were going to be ok, but the frequency response would fall a little short as the 34mm tweeter only goes up to 18kHz compared to the SH25-76 which goes to 22kHz and the SH25-76S which reaches the dizzying heights of 25kHz.

So my supertweeter is positioned to supplement the SH34-76 where its response starts to fall off, and bring the overall response closer to that of the studio models that my design aspires to be.

I asked for and received advice about this from Max Townshend and from two of the ATC staff, which gave me the confidence to proceed.

I hope that all sounds sensible!
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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