keeping another pair of QLS1's alive

[Nikkoholic]

Can I ask how you were able to remove the bottom section of your cabinets? I'll be needing to replace the cabinet bases on mine but didn't see the fasteners where the two section meet? Maybe mine are set up differently.

When you remove the Woofer and push the insulation out of the way you can see down into the crossover area. At the top of the opening on the tall speaker section (not the bottom crossover section) you will see 6 phillips screws around the perimeter or lip that forms the rectangular opening. Remove these and GENTLY bump the lower section. Mine have a black material that spaces the upper and lower section of the box. This black material has a bit of glue on it. It broke away pretty clean but I'd excercise caution to keep it in tack. All the wires are long enough to turn the crossover section at 90 degrees when disassembled. Also lay the speaker on its back prior to removing these screws!!
Hope this helps.

 

[cdfac]

i thought about accessing the XOs that way (mine are set up like yours), but i decided it would be more problematic than just pulling everything out through the woofer hole. glad to hear it worked for you, though! when you put the base back on, i'd recommend caulking the joint if that wasn't already in your plans.

 

[jimreeves]

Thanks Nikkoholic, I wondered about that. My pair have 3/4" by 3/4" stripwood stapled over that joint, probably obscuring the screws.

Finished the crossover rebuild yesterday and OMG!, what a difference it made for the better. Well worth the time and relatively low cost involved. I kept the existing coils, replaced all caps and resistors and disassembled and cleaned the pots. I did not replace the wiring and don't foresee a need to. Many thanks to you Chris for the incentive and advice to help get the job done. These are keepers!

Jim

 

[cdfac]

Definitely sounds like something on the XO plate then. Hm... The loose cap could be making more noise than you think. Not sure, though.

Right now I'm not biamping at all. Don't feel like I'm missing anything. When I get the other two amps back from their recap, I will probably give it a try though. And of course if I got hold of a big tube amp, then I'd try putting it on the top end though. As it is, I find that the speakers (mine, at least) are very well balanced with one amp, whereas with biamping the impedances subtly change when the straps come off and I have to work harder to dial the proper response in.

I'm not sure why you're missing midrange, since I've never noticed that at all. What sort of instruments are affected? Could be something set wrong, but more likely it's a wiring/XO component issue. I'm assuming all your domes are working properly?

Thanks cdfac, I'll check those other vibration things out. I don't intend on rebuilding the crossovers but I did use a silicone based cement so if I change my mind I should cut away fairly easy (I think).

I did find a loose capacitor and also glued that, but seem small to create the significant vibration I've been experiencing. FYI I run the the low frequency amp only with balance to the right, so I am only hearing low frequency in the right speaker and that is were the rattle is occuring. If I push on the plastic control panel I can minimize it but not completely eliminate it. Just want to cover all my bases while it's open, I hate removing the Watkins any more than necessary.

Also am replacing the hex screws fot the Watkins with equivalent phillip pan head screws (painted black of course). The hex head screws are very difficult to get a driver / socket around when installing them and puts way too much pressure on the surround ring trim (not sure what is is actually called).


Was reading through the history of this post and couldn't find if you were vertical biamping or horizontal at this time. Can you please tell me your preference if you have done both? I am currently Horizontal with an active crossover. Just makes sense to me to not make both amp channels produce unused frequencies. I assume you still have those Monster Yamaha's. I am running 2 Nikko Alpha 650's at 330w/ch each (plenty of head room now).

Thanks for your comments on the Kappa's, I have to say I think the QLS-1 has wonderful sound but on some music (and it varies) they are really weak on the midrange. This doesn't bother me too much because I don't really like strong mid's but, if you listen to other speakers (RS IIIB's in my case) I find that I am missing out on some sound occassionally. Have any of you QLS people experienced this? Or do I just have something set wrong.

 

[Nikkoholic]

I'm not sure why you're missing midrange, since I've never noticed that at all. What sort of instruments are affected? Could be something set wrong, but more likely it's a wiring/XO component issue. I'm assuming all your domes are working properly?

All domes are working right, I do get an occasional pair of ribbon tweeter dropping out, but I'm going to resolder those while I have the speaker on it's back. Also noticed the ribbon tweeter connector (spade terminal) in the crossover area was not pressed on all the way. That likely dates back to 1978 mfg. date. I deoxidized all the connections on the spade terminal strips.

So why is there, or how do you identify, the need to rebuild a crossover. Do you just not like the components Infinity used? Do they degrade over time? If all compenents are working and you rebuild is there truley an audible difference? I just hate to fix something that is seemingly not broken.

Thanks

 

[jimreeves]

So why is there, or how do you identify, the need to rebuild a crossover. Do you just not like the components Infinity used? Do they degrade over time? If all compenents are working and you rebuild is there truley an audible difference? I just hate to fix something that is seemingly not broken.

Thanks

Unless you are the original owner you can't be sure what shape your crossovers are in. If yours were anything like mine, someone before you had a "better" idea how to make these speakers work and modified the crossovers. While your box is open, compare your component wiring to the schematic I posted earlier in this thread.
http://www.audiokarma.org/forums/showpost.php?p=2870713&postcount=115

To your question, yes, crossover components degrade over time, particularly capacitors, so there is a benefit to heard with the change. Cdfac went over his refurb in this thread....
http://www.audiokarma.org/forums/showthread.php?t=215773

 

[Nikkoholic]

Unless you are the original owner you can't be sure what shape your crossovers are in. If yours were anything like mine, someone before you had a "better" idea how to make these speakers work and modified the crossovers. While your box is open, compare your component wiring to the schematic I posted earlier in this thread.

I bought these speakers from a local audio salesman, he only had them 6 months. I am positive there was no altering done. My crossover matches the schematic. And when I removed the lower section of the speaker it was evident this had neve been done before.

I think I may save the rebuild for a slower time in my life. Right now I have to get rid of the rattles and intermitent tweeter operations. Once I get the basics cleared out I may tackle more detailed refinements such as the rebuild. Good to hear it makes a difference, that take the experimenting out of the equation.

 

[cdfac]

Figured out the imaging problem with the unbalanced mids. Whew! The midrange pot on one speaker for some reason has a noticeably higher resistance at the same setting. After I balanced them out, everything is back to good :thmbsp:

 

[jimreeves]

Figured out the imaging problem with the unbalanced mids. Whew! The midrange pot on one speaker for some reason has a noticeably higher resistance at the same setting. After I balanced them out, everything is back to good :thmbsp:

Congrats on the sleuthing and the fix Chris! Please elaborate on your method for measuring the pots, or do you adjust them as you measure at the speaker terminals?

Any idea how a fixed coil in the pot could change resistence over time?

 

[cdfac]

i had the woofers out, and i just hooked up the multimeter leads across the taps on the pot. no idea how this really could've happened.

 

[jimreeves]

Here are some pics of the base section of my right channel QLS1 as I start the process of replacing them. If you can't tell by viewing them, when I removed the 3/4" pine stripwood that was stapled in place to hold the upper and lower cabinet sections together I found only 3 screws poorly attaching a 1" thick particle board "coupler" section to the base. The 3rd photo shows the edge profile which allows the 3/4" reveal between upper and lower sections of the cabinet and the 1/4" inset portion of the coupler at the front of the cabinet below the baffle. The 3 other sides of the coupler fall inside the upper cabinet only that 1/4 inch! Apparently the stripwood held everything together.

I plan to build new bases with 7 ply birch with walnut veneer but that will have to wait for the weekend. In the meantime I'll use some plywood strips to put this back together. I can't wait til Saturday to listen to these!

Any suggestions on a good source for walnut veneer?

Jim

 

[cdfac]

looking good, jim! i see your crossovers turned out very similar to mine. i look forward to hearing your impressions :yes: hopefully you like the new sound as much as i did. no idea about new veneer though.

 

[jimreeves]

Mine are sounding better than I could have imagined was possible. Amazing what good quality symmetrical crossovers can do for a pair of speakers! BTW, the caps worked out great. I'm down to cosmetic issues at this point.
As I said in Barter Town, I'm very grateful for your advice in getting mine up to snuff. I would've never gotten this far without it. Best of luck with your sale and your new investment!

Jim

 

[Nikkoholic]

jimreeves, you can get the veneer at Rockler they sell veneer on line and any supplies you may need. Here's the link to pressure sensitive veneer http://www.rockler.com/product.cfm?page=2213&filter=veneer
You want the "plain sliced Walnut". That's what our QLS-1's are made of. Coloration will be off since these have a 30+ year patina that is difficult to reproduce. You may experiment with some of the scrap pcs you'll have left over. Try various dyes and light stains to get the patina. Our speakers do not have simply have a very light oil finish on them. You can try mineral oils with some tint in them. But if the finish match is critical you may just call on a local finisher for advice or help.

As for your "bottom" assembly it is completely different than mine. When assembled the gap between the top and lower section is only 1/4". There is a 1/4" black spacer set in about 1/4" leaving a small reveal around the base of the speaker. When I disassemble the 2 the bottom of the upper section is a mirror image of the top of the lower section. In other words there is a rectangular opening in both the top and bottom section. Sorry if my instruction were confusing; who would have thought they built the boxes different. Also see the face of your speakers are black. I've got an old stereo review article when these speakers came out. They also showed the black face on their units. I've only seen the walnut versions. Yours must be an early serial number.

As for my "rattle". Put everything back together and it is still there. Just like before if I push in the middle of the rear control panel the rattle stops. Guess I should have dismounted it and re-glued and reattached. Very dissappointed. Other problem is I "upgraded" the hex head screws that hold the Watkins in with a pan head phillips. The head must be slightly larger so when the screws went in the really pushed their way past the fiber trim ring that is over the foam ring glue line. Not sure if they are going to come back out without tearing that fiber trim up. Any advice? Is this fiber ring replaceable or is this part of the foam suspension ring assemble? Obviously I've got to get the woofer back out.

On a good note. I noticed the speaker I worked on sounded significantly brighter. I deoxided the pots while it was open and cleaned all the spade connections. Could this really have made an audible difference? If so can't wait the do the other. The "cleaned" speaker also seems a little louder too. Can anyone explain that?

 

[jimreeves]

Nikko,
as soon as I took my cabinet apart I knew this was a different animal than yours....I think I'm getting cabinet envy now.
Your trim rings are probably tack glued to the woofer basket and the foam surround, so replacement would be tricky. Nevertheless, you'll have to remove the screws sometime and see what happens as you said. My watkins have foam trim rings rather than fiber, I have no idea why. I used #10 x 2" stainless pan head screws to hold mine in, with the heads painted black.

You might try stuffing some fiberglass or polyfill or rockwood against the inside of the terminal board, or you could pack some modeling clay against it. Or just cover the entire crossover section with a sheet of fiberglass insulation which should absorb the woofer back wave and vibration.

Cleaning the pots probably lowered the resistence between the signal and the drivers, making them louder and clearer, that sounds reasonable.

 

[Nikkoholic]

I used the same screws you stated. However these are new Watkins and the clearance around the screw openings is actually a little undersized. I thought by going to phillip head it would improve, since the hex head required a socket to be around the outside while installing. With the hex head screws I has to really push against the fiber ring to get the screws in all the way.

Any way I'll try to take them out. I may call Watkins to see if Bill has any advice. Not sure if I'll "upgrade" the screws when I deox the other speaker.

 

[jimreeves]

I've seen nylon spacers in the hardware section at Home Depot / Lowes that might work in your situation. Just slide the spacer on the screw and let it fill the depth of the fiber ring.

Does anyone recommend feet or spikes for these speakers or is floor coupling a good thing?

 

[cdfac]

if you have carpet, it might not hurt to have some sort of foot. OTOH, they're so heavy. maybe if you just used four small furniture sliders?

 

[jimreeves]

if you have carpet, it might not hurt to have some sort of foot. OTOH, they're so heavy. maybe if you just used four small furniture sliders?

On parquet (sp?) here, over concrete. I might try some sliders as you suggest. They're cheap and if it thins the bass too much I can chuck 'em.

Found some flat-cut, book matched walnut 2'x8' veneer for $20 bucks a sheet on closeout and ordered them today, we'll see why they're so cheap when they arrive :scratch2:.

Jim

 

[jimreeves]

I was reading through the owners manual for these last night and came across the attached paragraph. Since I always listen to my Q's without the grilles, it got me wondering what I'm missing (if anything). I looked over my grille frames and can't see anything like a "quarter wave plate". The description of a masonite "plate" to be provided in lieu of grilles is too vague for me to understand where it would be mounted.

Does anyone have grilles with this "quarter wave plate" installed? Can you explain where it mounts relative to the emits???