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Upgrading QLS-1 crossover to version 2.

chef free

chef free

Super Member
There are two versions of the QLS-1. Serial numbers over 7001000 are version two and have a different circuit on the the Watkins woofer. I replaced the 1400/1600 uf capacitors in my version one QLS with the newer 1400/1100 uf but I left the original 4.3 mH inductor. So I decided to change the woofer circuit to match the version two circuit and replace the original coil with a 6.5 mH.

Then a recent thread here indicated that many of the inductors used by Infinity were out of spec by half of the intended value to one tenth of the intended value. Do they wear out? Can all the vibrations inside a speaker wear through the insulation making the coil effectively shorter? I don't know but I decided to replace all the inductors in the crossovers.

I have ordered six new iron core ERSE inductors from PE. I intend to replace the coils in one speaker, measure the originals and report back my findings.

Stay tuned!
 
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:lurk: I've been reading that thread with concern as well...the erse look like the most reasonable replacement. There is some others but are pretty expensive.
Jim
 
chef free said:
Then a recent thread here indicated that many of the inductors used by Infinity were out of spec by half of the intended value to one tenth of the intended value.
Click to expand...

I hope you guys are not spending money because of what I measured, without doing some measuring and drawing your own conclusions first.

I have a sneaking suspicion that those inductors may have been measured at rated current. I may be way off base on this, but between this assumption and the fact they may have also been measured at a different frequency than what my devices are using, may yield some very different results. And, my inductor replacement is quite selective. I am not replacing everything in the crossover, only ones where I can identify a need/benefit. Remember, don't just look at individual inductors; think about them in the context of the entire circuit. Both rs-1b and myself have components that are quite a ways off spec as measured. But, in the context of the circuit, they come very close to the desired performance. So it demands very careful decisions.

Geoff
 
Coils arrived this afternoon. They are big and heavy! They sure won't fit where the originals are. A friend of mine is the lead tech at a company that tests test equipment, he has a nice LCR meter that I can borrow.

So tomorrow evening, step one, test the values of the new coils.
 
Tested the new coils at 120 Hz, here's the results:
5.0mH #1: 5.05mH, #2: 5.06mH
6.5mH #1: 6.61mH, #2: 6.61mH
20mH #1: 20.0mH, #2: 20.4mH

I also tested resistance, both AC and DC, which are the important ones?

I have opened up one cabinet and read the values off the coils:
The midbass circuit is marked 6.37mH. the version 2 crossover calls for a 5.0mH.
The Watkins vc-1 (4 ohm) is marked 4.33mH, the version 2 crossover calls for 6.5mH.
The Watkins vc-2 (2 ohm) is marked 21.36mH, the version 2 crossover calls for 20.0mH.

I had no idea that they changed the midbass circuit! Hopefully this will be an upgrade since I've always felt that there is something wrong with the way the midbass integrated with the rest of the drivers.

I'm going to swap out the 4.33 for the new 6.5 and have a listen.
 
I swapped out all three coils in one of my QLS-1. I played music and listened to just the woofers, just the mid bass and all the drivers at once.

I immediately noticed a reduction in upper bass response of the Watkins, which I found disappointing. Then I listened to some bass heavy music, Charlie Hayden, Grateful Dead drums, Charles Mingus, Nora Jones version of Hank's Cold Cold Heart and I found that the new coils made the bass and drums sound more realistic. I'm going to measure the original coils for L and R later tonight. I suspect that the newer coils may have higher resistance. The original coils seem well built, heavy with laminated steel cores, nothing cheap here.

The mid bass circuit sounds the same even though the new coil is rated 50% higher than the original. There sure is a lot of musical information between 200Hz and 600Hz!

The woofer was re-coned before I bought the speakers, inside the speaker I found what looked like cat damaged speaker cone bits. I'm assuming that the other original woofer has the 35 grams of mass that Arnie Nudell added to the speaker to get his 18Hz spec. This, along with changes to the LC circuit, is what, according to Bill Watkins, caused the speakers to dip to 1 3/4 ohms at certain frequencies and cause lesser amps to shut down.

I wonder what would happen if I swapped the two original coils on the mid bass circuit and the vc-1 woofer circuit...
 
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tubed said:
I forget where I read it, that the QLS-1s were individually fine tuned one way or another?
Click to expand...

According to Bill Watkins, Arnie Nudell added 35 grams of mass under the dust cover of the woofers to get the bass response down to 18Hz. Bill said that this is why the impedance dips to 1 3/4 ohms and puts lesser amps into protection mode, or worse.

I have one original woofer, with the black magnet, and a re-coned woofer with a silver magnet. The two look exactly the same other than the paint but I'm pretty sure whom ever re-coned the silver one did not include 35 grams of mass under the dust cover. The re-coned woofer, which is in the right side speaker, has always been louder than the original and this is still true now that I replaced the inductors in the left speaker but the difference remains.

Tonight I plan on swapping the woofers to see if the problem is with the woofer or the crossover. I'm also going to measure the impedance of all the driver arrays.
 
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I removed the woofers and measured all the driver array impedances. Here's what I found:

Left Right
EMIT array: 3.1, 3.1
Rear EMIT: 6.5, 6.5
Domes: 5.1, 5.0
Midbass: 6.7, 6.4
Woofer vc-1: 5.0, 2.0
Woofer vc-2: open 2.0

When I first got these speakers, I measured the woofers and everything was right; vc-1 5.0 ohms, vc-2 2.0 ohms, I'm not sure how the voice coil could fail. I played with the wires and got it to show 2 ohms for a second. I've thought that the right speaker was louder, sometimes even adjusting the balance control, then I would think I was wrong and turn the balance back to center. I can't imagine that changing the coils would do something like this! The original measured 21.37 and the new one was 20.00,

I'm going to remove the dust cover and see if there's some way to re-solder the coil wire but I'm wondering if I should get a new pair of woofers from Bill Watkins, they aren't cheap, $750 a pair!

I have an extra pair of midbass couplers, they are 8 ohm, if the originals are 8 ohm, maybe I'll swap them in. The spares measure 6.8 and 6.9 ohms.
 
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I hope you can get the woofer working properly. The new Watkins are a temptation even at the $750.00 price tag. I had mine rebuilt by millersound for way less than half that. Not sure if he replaced the 35gram mass in each. Maybe I'll email him tonight. They are very good. He also added a little bit of dynamat (?sp) to the underside of each cone so maybe that is it. They both measure around 5 and 2 ohm on the voice coils.

Others which have the new Watkins woofer say they do not suffer from bottoming out like the originals. I bet they are pretty freakin awesome. Since I changed the caps on mine to the version 2 values I have not had them bottom out.

You can be very thankful your tweeter arrays are measuring good....
Jim
 
I removed the dust cover and found that voice coil 2 has failed somewhere inside the bobbin. I scraped the insulation off the leads and tested continuity from every different point. I can't understand how this could happen but the speakers ARE 40 years old...

However I put the good woofer in the cabinet with the new coils and it sounds fantastic!

Not sure if this woof can even be fixed. Magicmarksey has one on Ebay with the same magnet structure and there's Bill with a pair of matching brand new woofers for three times the price. Not sure what to do next...
 
slimpikkins said:
You can be very thankful your tweeter arrays are measuring good....
Jim
Click to expand...

When I first got these speakers 9 of the 18 tweeters were quieter than the rest. I took each tweeter apart, on the speaker, and reflowed the solder from the rivet side. That;s what made the sound stage image so sharp!
 
Auction seller "donleesam" is parting out a pair of Quantum 3's (not mine). He has a Watkins woofer, as well as Quantum Emits. Maybe keep an eye out on his auctions too? There's two of those poly Watkins woofers available. Have a pair of each! See which sounds best?
 
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I called Watkins Audio today and had a very nice chat with Bill Watkins Jr. We spoke about the QLS-1, he told a funny story about trying out a new Infinity amp, he accidently dropped the needle on the record, not knowing that Arnie had delivered the thing with no limiter. He told me that the woofer blew it's self right out of the QLS-1! He also told me about how James Bongiorno from GAS called him and tried to say "Your woofers are destroying our amps!."

He told me that they could "look at" my broken woofer and see what, if anything could be done to repair it. After discussing everything I decided to buy a new pair.

I have to go on "vacation" to my in-laws next week so the woofers will be arriving Aug. 5th, stay tuned!
 
Ew! "Vacation" with the in-laws was much worse than I imagined! You'd think after 35 years I'd know what to expect!

Anyways, I came home to a pair of brand new Watkins woofers and they looked great. They are slightly deeper than the originals and have vented pole pieces. They come with color coded stickers so theres no reasonable way to hook them up out of phase. They have black poly cones and grey surrounds, I like the way they look, it's better than the clear poly. They measured 4.5 and 2.0 ohms exactly, my originals were 5.0 and 2.0.

I installed them last night and gave them a little listen. They sound really good, a little louder than the originals. I really can't notice any difference between the speaker with the newer coils and the one with the original coils. The one with the new coils does seem to have a little more mid/high, but it's subtle. The new coils may have higher resistance, I haven't measured the old coils yet.

Either way it's way too soon to tell which I like better. More listening later today!
 
Hmmmm... I'm liking these new Watkins woofers. I just listened to The Lamb Lies Down on Broadway, there's lots of Taurus bass pedals on that album and they're hard to reproduce. It never sounded better on these speakers, they seem to have a nicer tonal quality with no frequency of bass seeming significantly louder or softer. Also I found that I wanted the "midbass coupler" louder, going from 9 o'clock to 12 for now.
 
These new Watkins woofers sound so much better than the originals! Greater clarity and detail which really add to the "effortless" quality of the QLS-1. Everything sounds much more accurate and realistic. I'm really surprised but the more different music I listen to, the more improvements I hear.

I have had to completely change the crossover settings, mid bass up and domes down, rear tweeters ON.

Oddly enough, I can't tell any difference (so far) between the old coils and the new ones.
 
Five hours of serious listening with an audiofool friend yesterday. DVD remasters of Jethro Tull's Aqualung and Yes' The Yes Album, the latest Tedeschi Trucks band album, recorded on all analog equipment, The Grateful Dead's One from the Vault, a multi track recording and Yo-yo Ma, Edgar Meyer and Mark O'Conner's Appalachian Journey. That's a lot of great bass players!

Chris Squire's bass sounded very Rickenbacker like, Phil Lesh plays the whole bass, each note had the same tonal quality and volume, no peaks or valleys here! But the shock of the day was Edgar Meyer's acoustic bass battle with Yo-yo Ma's cello, whether plucked or bowed, each sounded so realistic, it was "like they were in the room with us".

I'm so glad I took the plunge and got these new Watkins woofers!
 
I would think that a Zappa fan would have tried some Bozzio, Levin, Stevens too. Tony Levin ain't too shabby on the bass either! But, you played YES, and Mark O'Conner, so I can't complain too loudly!

Oh yea, glad to hear that the new Watkins woofers have worked out so well. It's a shame that they're so pricey. Though, apparently worth it! :rockon:
 
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