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Upgrading QLS-1 crossover to version 2.

I finally got around to borrowing a friend's LCR meter and measured the inductance of the new and original coils. All measurements were made at 120Hz. Resistance is measured for AC.

New coils:
20 mH measured 20.2 mH, 0.88 Ohms
6.5 mH measured 6.61 mH, 0.48 Ohms
5.0 measured 5.05 mH, 0.59 Ohms

Original coils (had a stickers with values hand written on each)
21.37 mH measured 16.89 mH, 0.98 Ohms
4,33 mH measured 3.62 mH, 0.37 Ohms
6.37 mH measured 4.44 mH, 0.52 Ohms

The originals are way out of spec, I'd be cool with 10% but these are way off! How do coils wear out?

The AC resistance is similar however, I guess that's not what's making the bass so much louder in the right speaker (the one with the original coils.)

The originals have louder bass but do they sound better? Hard to say, If I turn the balance it effects the high end as wall. Maybe time to vertically bi amp these speakers (like Infinity suggests), and just turn down the bass on the right.
 
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Well folks this whole trip is driving me crazy!

I have been listening to these two speakers for a month now and I still can't tell which sounds "better". I've listened to a bunch of different music in mono, (which BTW, sounds great!), one night I was convinced by the stand up bass on Nora Jones' Come Away With Me CD, that the new coils sound so much better, clearer and cleaner, but then the next night I'm certain that Phil's bass sounds much more "present" on Dicks Picks # 10 through the original coils.

I listened to the woofers alone and found that the crossover point is much higher with the original coils, there's a big difference between the original 3.6 mH (labeled 4.3) and the new 6.5 mH.

I listened to just the tweeters/domes/mid bass and found that the change from a 4.4 mH (labeled 6.37) to a 5.0 mH is noticeable too. But why would they change the crossover between the mid bass and the domes if the problem was woofers bottoming out?

Does anyone know what the original specs were? I only know what was in my speakers. With these "improved" Watkins woofers I could built new original spec crossovers if I knew what they were...
 
When I updated my QLS crossover I used what was original to that speaker which in turn matched the diagram.
As to original woofers, I once talked to Watkins who stated all his woofers would be identical electronically, the difference be power handling capabilities by way of the different magnets.
I would think his new woofers would also be made to be "identical"?

As far as the woofer rolloff, matching the woofer to the midbass with a different coil value would seem tricky.
http://www.infinity-classics.de/mod...ource-QLS-1/QLS_1_crossover_schematics_02.jpg
QLS_1_crossover_schematics_02.jpg
 
I have the older, black face QLS-1, it has a 1600 uF in place of the 1100 as in this Feb, '78 schematic, the 5.0 mH was a 6.4 mH coil and the 6.5 on vc1 was marked 4.3.

The current Watkins woofers definitely sound better than my originals, Bill Jr. told me that they "bumped out" the magnet so the woofers wouldn't bottom out. Bill Jr. was surprised that I thought they sounded better.
 
Out of curiosity, which of the two original woofers were installed on your early QLS, bigger or smaller magnet?
 
The reason I asked was Infinity changed the cabinet
and the crossover so I thought perhaps the woofer was also changed to a bigger magnet.
That being said I've only come across the smaller magnet in the smaller Quantums like the Q3 and Q4.
 
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That's interesting fact that I will keep in mind. I've been told that the two magnet structures and the two types of cone material are totally interchangeable but I would want my woofers to match exactly. I sure wish an original crossover schematic would turn up!

BTW, last night Jason Isabell's Something More Than Free CD sounded better on the new coils. The original coils sound like the loudness is on, which is great for older recordings but sounds boomy on modern, full-range recordings.
 
chef free said:
I sure wish an original crossover schematic would turn up!
Click to expand...

So, the crossover schematics on Infinity-Classics aren't correct, or are a later version? Just curious...

http://infinity-classics.de/technik/manuals/Quantum_Line_Source_1_technical_sheet.pdf

QLS_1_crossover_schematics_01.jpg
 
That's the Feb. '78 revision of the crossover, it's correct for QLS-1 speakers with a serial numbers higher than 7001000; the "veneer baffle" model. The original, "black baffle" model featured a 1600 uF on vc-2 instead of the 1100 shown on the diagram. Apparently the originals would bottom out the woofers on stuff like the heart beat intro to Dark Side of the Moon. Also the coils were different; mine had a coil marked 4.33 mH (measured 3.62 mH @ 120 Hz) where the diagram shows a 6.5 and a 6.37 mH (measured 4.44 mH) where the diagram shows a 5.0.
 
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The new coils make TV/movie dialogue much clearer. I used to have to turn the 150 Hz tone control down to understand what the actors were saying.
 
I FINALLY replaced the original coils in the right speaker tonight. I started this project in June! But I'm like that, it takes me a long time to make decisions (but I usually make good ones).

The original coils were labeled 18.37, 4.48 and 5.78. Compared to the left speaker which were labeled 21.37, 4.33 and 6.37. That makes me think the original specs were 20.0, 4.3 or 4.5 and 6.0.

So tonight I listen! I'll report back in a few weeks...
 
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Sturgill Simpson's A Sailor's Guide to Earth, Vieux Farka Toure LIVE, King Crimson's Lark's Tongues in Aspic, Patricia Barber's Blue Cafe', and Drive by Trucker's American Band have convinced me that these coils sound great! These are now the best speakers I've ever had!

With each repair and improvement they get a little better. I also found and fixed an air leak around the left mid bass coupler and I found that annoyingly intermittent buzz, it was the square plastic face plate on the lowest right dome. They have new woofers, reflowed soldier on all the EMITs, fresh caps and coils and clean pots. And the rosewood has been cleaned and oiled with Howard's Restore a Finish and some fine steel wool. They look and sound as good as they did when they were new!
 
chef free said:
Sturgill Simpson's A Sailor's Guide to Earth, Vieux Farka Toure LIVE, King Crimson's Lark's Tongues in Aspic, Patricia Barber's Blue Cafe', and Drive by Trucker's American Band have convinced me that these coils sound great! These are now the best speakers I've ever had!

With each repair and improvement they get a little better. I also found and fixed an air leak around the left mid bass coupler and I found that annoyingly intermittent buzz, it was the square plastic face plate on the lowest right dome. They have new woofers, reflowed soldier on all the EMITs, fresh caps and coils and clean pots. And the rosewood has been cleaned and oiled with Howard's Restore a Finish and some fine steel wool. They look and sound as good as they did when they were new!
Click to expand...

That sounds like it was a lot of work, but very much worth it in the end! And with the musicians and bands that you like, the effort is definitely warranted.

Also, when you mentioned "fresh caps", did you recap the whole speaker, or just the bass circuit? I'm always curious about recaps. Especially brands and any changes in sound? What you liked and the improvements heard? Just trying to pick some decent brands of caps to use for personal recaps, and like feedback from owners that have updated their speakers. Reinforce my own choices, if possible?

Thanks!

Almost forgot - Did you add any mass to the new Watkins woofers, to match what Arnie did with the originals?
 
StimpyWan said:
That sounds like it was a lot of work, but very much worth it in the end! And with the musicians and bands that you like, the effort is definitely warranted.

Also, when you mentioned "fresh caps", did you recap the whole speaker, or just the bass circuit? I'm always curious about recaps. Especially brands and any changes in sound? What you liked and the improvements heard? Just trying to pick some decent brands of caps to use for personal recaps, and like feedback from owners that have updated their speakers. Reinforce my own choices, if possible?

Thanks!

Almost forgot - Did you add any mass to the new Watkins woofers, to match what Arnie did with the originals?
Click to expand...

Yes, I continue to be impressed as I work my way through different music. It was worth all the effort and I documented as much as I could so that the info is in one place.

I used 5% Parts Express caps and replaced only the electrolytic ones, they were on the bass and "midbass coupler" circuits, they were those Made in Mexico, red and black ones from the '70's, all swollen and leaking. I left all the film caps as many folks told me that they last forever and I've found that they are part of the "Infinity Sound".

I did not add any mass to the new Watkins woofers for several reasons. My original woofers did not have any mass under their dust caps. I changed the woofer circuit to match the second version of the QLS-1, the veneer baffle model, woofer circuit. Infinity changed the circuit because QLS owners complained of the woofers bottoming out on heavy bass passages. And I would not have the slightest idea how to choose the amount of mass, nor do I have the test equipment or ability to use it, to do it right.
 
Bad news everyone! The left speaker mid dome pot has failed! It won't turn or pass signal. :confused:

So I removed the woofer and de-soldiered the pot, then I attempted to remove the nut from the back of the pot but it is melted or smashed into the plastic and it will not turn. It is a replacement pot that is identical to the original except that it has a flush cut shaft with a screwdriver slot in it. I'd like to get it out without removing the pedestal, maybe I'll cut the nut off with a Dremal tool.
 
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