• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

XRT20 Speaker System Restoration (and questions)

w1jim said:
In replacing the foams is there some sort of a treatment I should use on these? Perhaps whip up some brushable latex and apply it?
Click to expand...

You're probably on the right track, but I'd do a straight refoam and give them a listen first.

These were originally installed by Gordon Gow and he mounted the tweeter columns on the wall about 1 foot from the corners.
The manual (which came with it) specify that the wall should be divide into thirds and the columns mounted 1/3 of the way from each corner. Any thoughts on how I should mount these?
Click to expand...

It'll sound like a cop out but that's really room dependent. The 1/3 thing will minimize room interaction but that might not be what's best in your room. You'll have to play with them.

Lastly (for now) since my anticipated mounting location precludes the flush mounting I plan on building some brackets that will closely mimic the original CS20 brackets which position the rear of the tweeter columns and woofer/midrange boxes on the same mounting plane.
Would there be a problem / loss of imaging/soundstage if I position the tweeters forward about 6-8 inches?
Click to expand...

It looks like the combination of spacing between the modules and putting the backs on a plane is their route to time aligning the tweeter and woofer modules. If the crossover is designed around that spacing then it is probably the best way to go. If it's not part of the design then some experimentation might give a better result in your room. Not much of an answer, huh?
 
We got the second pair from the factory, must have been fall of '79 or spring of '80, and introduced them to the Midwest. The first pair was shown at McQuires in the DC area and John sent us a lighting and draping system to hide them and then allow a reveal of the speaker system with a lighting change.

I placed the tweeter columns at a distance of just less than the height of the listening triangle, which was about 40% of the room width. I always found that for maximum sound stage outside the speakers the 8 inch driver was the most critical for placement, too far apart and a listening hole would open up. Back then we only had a MQ104 available and the tweeter column gave little issue but the 2-12s would really excite the room nodes.

When Gordon Gow flew in the next week to make the presentation I had the chance to introduce him to Crystal Clear's new Direct Disc recording of Copland's Fanfare for the Comman Man which became the intro piece for all further demonstations. (He bought 3 copies and insisted on paying retail)

Gordon had done a quick listen...checked and confirmed my work with the MQ104 and AA2, then insisted we pull the demo turntable and do a complete recalibration to make sure "his speakers" had the chance to sound as best as they could. This was the first time I set up a table with him and he was very particular, paying very close attention to maximising the cartridge's crosstalk. The hoot was with a group of 50 or so there (including dealers from Chicago and Detroit) to hear the speakers, how long he made them wait for the chance to hear them, while he explained our time spent calibrating the table and my voicing the speakers.

Went on to install a dozen or so pairs over the next few years and the one thing about them that was for sure... they would certainly own the room.
 
Last edited:
Wow, I let that one sit a percolate a little before I hit send and missed most of the thread. Forget what I said. :D
 
Own the room? I'd go with that!

Got them all set up and running.

First impression (after "wow") is that these are not wanting for bass - I went DSOTM on them and I could feel body parts moving that usually need intervention to move.
I'm talking earth shaking bass, the kind of bass that make my modded Klipsch Fortes sound like computer speakers.
And not boomy excessive bass - just plenty of it and it goes down low.
The sound stage on these is similarly impressive - wide and deep.
So far I've played the DSOTM, MFSL American Beauty and the "For Duke" LPs.
Next will be some acoustic stuff and experiment with repositioning them.

After I get used to them I'll do some frequency measurements and see if the EQ is necessary.

Oh, I need a bigger house!


attachment.php
 

Attachments

  • xrt20A.jpg
    xrt20A.jpg
    74.7 KB · Views: 1,961
Under almost all circumstnces the speakers DO NOT NEED eq even the bottom octave, but almost always a customer's room did. In other words few could have us design a room to accomadate these speakers, we always had to correct the issues the room inflicted on the speakers.

What are your room demensions?
 
Bad news - two of the tweeters on one panel are blown out / Good news, there's a seller on ebay offering them right now. I bought 4 of them.
In the interim I put in a 15 ohm / 25 watt resistor to replace the 2 of them (which are together / in series).
Even with 2 bad tweets it sounds most impressive.

c_dk said:
Under almost all circumstnces the speakers DO NOT NEED eq even the bottom octave, but almost always a customer's room did. In other words few could have us design a room to accomadate these speakers, we always had to correct the issues the room inflicted on the speakers.
What are your room demensions?
Click to expand...
Sounds like a matter of semantics - the room, speakers and electronics all create the sonic environment. To correct the room would require major construction and treatments whereas it is easier to use an equalizer to compensate. Also my ears aren't "flat" either so equalization will be to a certain extent personal to me.

Room dimensions to follow shortly.
 
Those are some of the most ridiculous speakers I have had the pleasure of listening to. DSOTM was pure insanity.

So. much. bass. They sound great. Would be interesting to hook those up outdoors in a field or something!

:)
 
nate86 said:
Those are some of the most ridiculous speakers I have had the pleasure of listening to. DSOTM was pure insanity.
So. much. bass. They sound great. Would be interesting to hook those up outdoors in a field or something!
:)
Click to expand...
I think I ruined Nate for those spiffy Allisons he just got :scratch2:.
I had my audiophile friend Walter over today - even he was impressed as to the smoothness (he figured with all those tweeters they would be shrill) and effortlessness to which they reproduce at a ariety of volume levels.
What I apparently need is a bigger room to really let these sing - not that they suck now.
Still - :banana::banana:.
 
I got my 2 replacement tweeters today and got them installed - and a perfect opportunity to show off the guts of one of the 4 tweeter panels. You can also see the single power resistor that substitutes for tweeter #25. There is a total of 24 tweeters per side in groups of 5 each; the resistor is #25.

How do they sound - well simply awesome! The bass response is substantial and the line arrays of tweeters present an impressive image.
I've been playing my Telarc digital 1812 overture - the canons are just so intense!


attachment.php



attachment.php
 

Attachments

  • tw1.jpg
    tw1.jpg
    49.5 KB · Views: 406
  • tw2.jpg
    tw2.jpg
    44.7 KB · Views: 340
Can relate...imagine openig up these huge boxes and setting them up in 1979!!! You need to listen to Crystal Clears Fanfare to make it back to the future.
 
c_dk said:
Still can not believe any of these tweeters would fail. Did the flexible lead fail?
Click to expand...
No, the flexible lead into the coil was intact - I was hoping I could fix it. There was a break somewhere in the coil or where the flex lead met the coil.
The 2 bad ones where on 2 different series "strings".
Important thing is that I was fortunate to find replacements cheaply and the system is working nicely.

After listening for a while it appears that the speaker/room combination is a little weak in the midrange so I've put my SG-9500 into the system and am starting to play around with it a bit.
 
From your picture is RH speaker close to a corner? The LH speaker will have a very different bass curve with the open dooway. See the white paper on Mac speakers I posted in the Mac tech sticky.
 
The response of each speaker pair is definitely going to be different. The right speaker is adjacent to an open doorway which then abuts a wall.
So it's almost in a corner - with a doorway in the way.

Almost every audio system is going to be in an imperfect environment.
I'll have to live with it unless I get a new house which isn't in the plans.

I had some AKers over today and the consensus is that the system sounds "big" before it sounds loud. Not to say it doesn't go loud.
 
What we would do with a AA2 and MQ107 is adjust each speakers response to each other, that is duplicate each other for the best imaging and to minimize bass issues.
 
Did you check the electrolytic caps while you had the woofers out? In a previous thread I documented the correction of crossover issues in similar vintage Mac speakers caused by tired caps which caused driver blending problems. Could easily be your midrange issue.
 
You must log in or register to reply here.
Back
Top Bottom