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Unexpected project...Infinty IRS Beta

The woofers in the Betas are all single-voice coil units, not Watkins double-coil units, AFAIK. One woofer has the accelerometer attached in each tower, which makes the servo work.

Skip the following if you're already familiar with the Beta's quirks:

I noticed that you're running a Threshold amp. Which model is it? My first pair of Betas was bought new, along with a Threshold SA-4e for the tops and S-550e for the bottoms. Great sound, but having more choices to experiment with today, I prefer McIntosh (autoformers) or tubes for the tops. EMITs, EMIMs and L-EMIMs just seem to like tubes and autoformers better than any regular SS design.

The bass towers just need low-impedance watts, the more the better. Be careful what amp you use for the bass, as the wrong amp choice or gain setting on the servo can generate an unbelievably loud howling noise from the bass towers, in a runaway feedback loop. While you're going deaf, the poor amp is going into overload. Also, IIRC, the amp has to be non-inverting. Read the manual, as my 58-yr-old memory is definitely not reliable... although I'll NEVER forget that howling noise.
 
Negotiableterms said:
The woofers in the Betas are all single-voice coil units, not Watkins double-coil units, AFAIK. One woofer has the accelerometer attached in each tower, which makes the servo work.

Skip the following if you're already familiar with the Beta's quirks:

I noticed that you're running a Threshold amp. Which model is it? My first pair of Betas was bought new, along with a Threshold SA-4e for the tops and S-550e for the bottoms. Great sound, but having more choices to experiment with today, I prefer McIntosh (autoformers) or tubes for the tops. EMITs, EMIMs and L-EMIMs just seem to like tubes and autoformers better than any regular SS design.

The bass towers just need low-impedance watts, the more the better. Be careful what amp you use for the bass, as the wrong amp choice or gain setting on the servo can generate an unbelievably loud howling noise from the bass towers, in a runaway feedback loop. While you're going deaf, the poor amp is going into overload. Also, IIRC, the amp has to be non-inverting. Read the manual, as my 58-yr-old memory is definitely not reliable... although I'll NEVER forget that howling noise.
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Yes, I've heard about the howling noise. Numbdiver experienced it and his testimonial sounds about like yours, NT. I hope I'm not on here in the next few weeks making my own testimonial.

As far as amplification goes, here's what I have on the shelf....

Threshold S-300 (with a second one available to me for loan w/option to buy)
Aragon 8008
Soundcraftsmen MA5002 (x2)
Hafler 500
Phase Linear 700B

I have others, but don't think they'd work as well as what I listed above...including an ST-70.

My plan is start off with the Threshold on the planar panel and the Aragon on the LF towers as it's not quite as nice sounding an amp as the Threshold but does put out 400w at 4 ohms with a heaping helping of current.

Preamp is a Dared SL2000a.

Thanks for the tip on checking the wiring, BTW. And as far as relocating to the Infinity forum...I think I'll keep it here as the all the Infinity guys find their way over here anyway but non-Infinity guys tend not to drift to the Infinity forum and I'd like to share what's goin' on here with everyone. Thanks for offering, though.

- Michael
 
tomlinmgt said:
And as far as relocating to the Infinity forum...I think I'll keep it here as the all the Infinity guys find their way over here anyway but non-Infinity guys tend not to drift to the Infinity forum and I'd like to share what's goin' on here with everyone. Thanks for offering, though.

- Michael
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This is the reason many here do not want any more manufacturer forums. If its a good thread people will find it. Just a comment about the recent suggestions for multiple new manufacturer forms.

Now that there is an open invitation to drop by for a listen...watch out for the parties that may get started when a couple guys tell their friends and your house fills up with AKers.
 
tomlinmgt said:
I dont think the IMG woofers were Watkins. I was under the impression all of Watkins designs used by Infinity are DVC and the IMG woofers are not DVC. And I don't think I've ever heard of Watkins having any servo designs. What Doug was measuring that he thought was a second voice coil were the terminals for the servo cable. They're positioned on the side of the magnet opposite where the voice coil input terminals are so it looks a lot like a DVC design.

And it's not the frame that sags, Ken. It's the spider.
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I always thought that what people called the spider was the spokes in the basket because they kind of looked like the legs of spider with the motor being the body, but now I know better, thanks!
 
Ken Boyd said:
I always thought that what people called the spider was the spokes in the basket because they kind of looked like the legs of spider with the motor being the body, but now I know better, thanks!
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I know, right? And the pleated membrane that is the spider looks nothing like one!
 
progress report

I've finally reached a point where I can start moving things ahead at a faster pace with the Beta restoration. I had several ducks I needed to get in a row before I could even think of setting up the Betas, so until I got those items marked off the list I didn't even bother with working on the speakers themselves as I have plenty of other, non-audio related irons in the fire at all times.

First thing was to increase the size of the listening space. I had a usable 14'x18' of floor space which I felt would not be sufficiently wide enough to accommodate the four towers. I was able to increased the floor space to 16'x20' by removing and relocating some utility shelves and moving a faux wall two feet to increase the width of the room which in turn necessitated a relocation of all acoustic treatments. Of course, this was a bit time consuming since the room response changed with the relocation of boundary layers so the room had to be measured again and a trial and error with the placement of treatments ensued. I'm still in the process of treating but I'm probably 70% of the way there. What this really became was a total listening space renovation and since my listening space is the garage where I still store stuff and have a work area it was rather time consuming to get it all sorted out with maximum efficiency. Completion of this step was the biggest hurdle and I'm very glad it's now, by and large, behind me.

I also needed to get my electronics in order as I decided I wasn't going to attempt to feed these things with any electronics that weren't fairly new or totally restored. This meant the pair of Threshold S/300's got a total recap (and a little bit of hot roddin' with higher value main caps and some other tweaks), the Infinity Servo Control Unit got a total recap and inspection, and I decided to replace the Dared SL2000a preamp with an Audio Research LS2B Mkii. I got all the parts to make up the bass tower servo cables and am having Blue Jeans cable make up unbalanced interconnects to run between the balanced outputs (XLR) of the ARC pre into the unbalanced inputs (RCA) of the pair of Thresholds.

So this past weekend I had some time to start cleaning and testing the mid/high planar panels. These things were incredibly dusty so a deep cleaning took me a few hours for just one mid/high planar panel. All drivers and level pots are working and seem to sound like they're operating normally. There is some delamination of the nickel plating on the EMIMs so I suppose I'll need to address this sooner than later. I "popped the hood" to take a look at the networks and was impressed to find all poly Solens and Wonder Caps used throughout....so I shouldn't have to worry about any cap replacement. The proverbial ball is finally rolling!

- Michael
 

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Well, you're certainly thorough if nothing else. Glad to hear you've had some progress. I'm going to be waiting for the next installment.
 
Spectacular set up and gear you have! Would love to hear those someday. Or any of the other Infinity's you have. I have RSIIIa's and love them. I can only imagine (and drool) at what those must sound like!
 
halo71 said:
Spectacular set up and gear you have! Would love to hear those someday. Or any of the other Infinity's you have. I have RSIIIa's and love them. I can only imagine (and drool) at what those must sound like!
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Thanks halo. The QLS-1's indeed set a pretty high bar. But true dipoles they ain't, and there's a magic with dipoles I truly appreciate (I own Maggies as well). The Betas have it and I can't wait to get it back in my rig. :yes:
 
Yep, no awards here for expediency! I've commited myself to providing an optimum acoustic environment for the Betas, so a good chunk of my free time has been diverted from the Betas to build diffusers for the front wall...five of them to be exact. At about five hours build time per unit it's been a slow go. I'm over half-way done with the last one. After that it's back to the Betas. I can see the finish line!

Here's the diffuser build....

http://www.audiokarma.org/forums/showthread.php?t=535105
 
Unfortunately this is the living room.
I'm also afraid that I may not ever be able to get rid of the Bozak's now that my wife has fallen in love with them.:sigh:
 
EWizard said:
Unfortunately this is the living room.
I'm also afraid that I may not ever be able to get rid of the Bozak's now that my wife has fallen in love with them.:sigh:
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Is that a bad thing? I've never heard a pair, but lotsa' luv 'round here for Bozaks. Are they the big 'uns? I remember I bought some JBL L100t's (back a few years ago when I was new to this audio thing) from a guy who was unloading them to make room for some big Bozaks...Concert Grands, I think. He was an older cat...x-JBL employee and (small) recording studio owner and he was pretty excited about getting the Bozaks.
 
Not a bad thing at all actually. They sound sublime.
I'm just the type, like you, that likes to change things around.
It just means that if I want to put in anything else, I'll have to make it look just as nice as the Bozak's.
There are worse problems...
:D
 
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