Another QLS-1 thread

A nice journey for sure.

My son has them in a bi-amped audio research setup. To me, I just think they love a big tube amp for those mids. It really changes everything and like you said...you can sit back and hear the benefits of the line array compared to a 3 way crossover system. I can imagine these being far less impressive if Arnie had not gone with that line array decision. But that sound does hit you in the chest all the while.

And your correct---Eddie Vedder sounds like he's right there, doesn't he? What a voice, at least back then.

And they do handle tough loads w/ bass and percussion heavy electronic music. That stuff is real tough on systems and amps and everything, really. Just try cranking up Chemical Brothers stuff to other speakers and see what happens. 140 to 160 beats per minute with all that emphasis down low is murder on bass and low midrange. But you capture that and the subtle goings on in the upper midrange. Like Nudell said, that's the toughest thing for a speaker designer; powerful dynamics and then handling soft and subtle. Almost always, what you get is 1 or the other. Then again, that is exactly why I love infinites.

The only other thing I can say is that they sure do seem to respond to MIT cables well. Big open room.

It's nice knowing you are set for a while, isn't it? How many other electronic products can you say that about? So so many have come and gone. And you are sitting there with what, another 15 years? Think about that---55 year old speakers and still extracting those sounds in the year 2030. What a design and build quality. How many 2015 speakers are going to be pulling that off by 2070?
 
Thanks for the reply. Yes, ARC tube gear is great on Ifinity speakers. I have a D115 which is 100wpc. It will be tried on the mid and tweeters soon. I setup the Philips amp and Pre amp a while ago to make sure it functioned properly with thoughts of flipping them and have not had a good reason to remove them.
Jim
 
Room size and shape is probably just as important for the QLS-1s to perform well, perhaps more so than having the "best" amplifier.
IMHO:)
 
You are probably right about room size but...I would love someone to tell me what would sound better in my small room after they listen to the QLS for under a grand. They are amazing. My brother who loves this stuff too was simply blown away. He's had (and has) a lot of gear (including my RSII on loan) and agrees they are very special and puts them up in the category of about the best he has heard. Until we get a bigger house this room will have to do.

I have a setup in the basement (IIB down there) which is a bigger room. Nothing ever sounds as good as it does in my designated room. May be the open rafters. Someday I may try to make that space better and place the QLS down there.

Another thing that I feel makes a big difference is having a giant stack of gear, albums, whatever, between the speakers. My rack was against the wall and the speaker baffles were well in front of it. After I moved my stuff to rear side of the room a few years back it was like a revelation. I will never have anything between my speakers again as long as I can help it.
Jim
 
Jim, This is one heck of a nice thread ! I was wondering if new pots are available, mine are in really poor condition. And as far as updating the crossover I would not have a clue where to start !. I have so much to learn but I am up for it. I can not believe you got them up and running for under a grand. That is crazy good !! Do you have a complete wiring diagram ? I will try not to be to much of a pest here. Thanks
 
no on the pots....they come apart and can be cleaned up, unless they were like mine (badly corroded )
 
Larry, I did not rebuild the crossovers. They are fine. I did have to remove the pots to clean them. Just unsoldered one at a time, cleaned it and soldered it back in. Mine were filled with blue corrosion and are like new now. Hardest part was removing the back plate and sealing it back up. The xo is nice because you can unplug the wires (that's all nice tinned copper wire btw) and remove the back plate from the cabinet without unsoldering anything. Here's a schematic from a very fine website.
http://www.infinity-classics.de/models/Quantum-series-1976/index-Quantum.htm
http://www.infinity-classics.de/technik/manuals/Quantum_Line_Source_1_technical_sheet.pdf
The new pots that value are not hard to find. These may work if they will fit on the board. May need to move some components around.
http://www.ebay.com/itm/25W-5-OHM-H...eter-Rheostat-Variable-Resistor-/130697071117
I finished my speakers at just under a grand. Price, gas, tolls, and rebuilt woofers, everything. They are not a perfect looking pair but are working properly and are very presentable. Well worth the time and effort.
Jim
 
Jim, You did a super job on them, And looks really do not matter to me. It is that distinctive sound reproduction they have is all that matters to me anyway! I find it odd that no one make a pot that will work with them. I am in the process of just getting subs I need. I for sure need at least on tweeter and the movers smashed up the grills beyond repair. Jerks! I have so many different things going on. I am repairing Motorcycles for income and getting my race bike ready so I may have to put the speakers on hold for a bit. But none the less I will bring them back! I can not tell you how much I appreciate yours and everyone else's help here. A really great bunch of people! I can't wait to hear the speakers again. Nothing I have ever listened to even comes close to the sound reproduction from them. Everything is so tight when they are working properly. I hope I can achieve the same results. And I will send the subs to Miller for sure. He did a fine job on yours, they look beautiful! Before purchasing the subs I will make sure that they are rebuild able. And I will try my best to save the pots!. Take care--
 
I wonder how many QLS owners listen with the rear EMIT in circuit.
Engaged the impedance should be double the 2.9 ohm array, give or take, and perhaps reduce output from the front tweeters?
I never measured the rear tweeter impedance and don't know what it should be.
Maybe other QLS owners will see this post and comment.
 
After a few weeks of listening the woofers were starting to bottom out on heavy bass. Not all the time but enough to make me mad. These are the older series with the 1600uf capacitor on the 4 ohm coil. I assume the surrounds are breaking in and now allow this. Maybe this was why the previous owner had those super thick upside down surrounds on the woofers. After talking to Chef free about this and seeing his work on his I decided to change out the 1600uf group of caps and replace them with 1100uf like the second series xo's. While doing this I noticed the inductor is 4.5 instead of 6 like on the schematic.

After changing those caps the woofers only bottom out at very very heavy bass at extreme volume so it is much better. Other than that they sound about the same as far as I can tell. While I was at it I replaced the mid bass coupler cap and the 1400uf caps on the 2ohm coil as well. Question is should I change out that inductor to 6.5? I do not know enough about a crossover circuit to know what the difference would be.

By the way the old caps measured fine...probably could have just clipped two 200uf caps out of the circuit for the same result.

Any help on the inductor question would be great!

Btw while apart I measured the impedance of my rear emits. Both 6 ohm.
Jim
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I wonder how many QLS owners listen with the rear EMIT in circuit.
Engaged the impedance should be double the 2.9 ohm array, give or take, and perhaps reduce output from the front tweeters?
I never measured the rear tweeter impedance and don't know what it should be.
Maybe other QLS owners will see this post and comment.

I go back and forth on the rear tweeters. With them on the sound stage is wider but the center image is less focused. I've had them off for the last few months. I measured their impedance and found 6.1 ohms on the right and 11.8 on the left! So I pried the cover off and opened the tweeter up without even removing it from the cabinet! It was easy with the rear tweeter design, just remove four of the cover screws, insert a pair of longer, 1 1/2", 6-32 screws in, remove the last two cover screws and it was open with the diaphragm exposed. I touched a hot, well tinned iron to each solder point until it just gave a little. Viola! 6.1 ohms!

After a few weeks of listening the woofers were starting to bottom out on heavy bass. Not all the time but enough to make me mad. These are the older series with the 1600uf capacitor on the 4 ohm coil. I assume the surrounds are breaking in and now allow this. Maybe this was why the previous owner had those super thick upside down surrounds on the woofers. After talking to Chef free about this and seeing his work on his I decided to change out the 1600uf group of caps and replace them with 1100uf like the second series xo's. While doing this I noticed the inductor is 4.5 instead of 6 like on the schematic.

After changing those caps the woofers only bottom out at very very heavy bass at extreme volume so it is much better. Other than that they sound about the same as far as I can tell. While I was at it I replaced the mid bass coupler cap and the 1400uf caps on the 2ohm coil as well. Question is should I change out that inductor to 6.5? I do not know enough about a crossover circuit to know what the difference would be.

By the way the old caps measured fine...probably could have just clipped two 200uf caps out of the circuit for the same result.

Any help on the inductor question would be great!

Btw while apart I measured the impedance of my rear emits. Both 6 ohm.
Jim
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I've been noticing that my right speaker's louder than my left so I opened them up and measures the tweeter array. Sure enough, the right is at 3.2 ohms but the left measures 4.2. I guess it's time to refresh all the tweeter soldier points. That looks like a lot of work to do a simple fix! While I was in there I noticed that my speakers have that 4.5 mH inductor too. I wonder if we should change them out. It would be a lot easier than doing the tweeters!

My old, bulging, cracked, leaking, crusty caps measured fine with a DMM too, actually closer to their stated values than my new, replacement, 5% tolerance caps. However a DMM does not have an ESR tester, that it the only way to know if the cap has the correct value through the whole audio range. As I understand it, the cap might test perfect at 1 kHz but be far out of spec at 20 Hz or 20 kHz. I'd bet serious $ that they were dried out. Those red and black caps have a bad reputation!
 
Nice job guys.
I agree with testing for high ESR as from what I've read, too much will hinder the caps performance radically even though the capacitor measures within uf specs.
 
After doing some reading and calculating this is what I've figured.
Vc1 5ohm 1600uf and 4.5 coil low pass around 182hz high pass is 20hz (original qls1)
Vc1 5ohm 1100uf and 4.5 coil low pass the same high pass is 29hz (what I have now)
Vc1 5ohm 1100uf and 6.5 coil low pass around 122.43 high pass 29hz (updated qls1)
Changing to a 6.5mh coil would change the low pass from 182 to around 122htz. So it would make sense to change out that coil to be closer to what the newer qls1 are. When I get a chance I will do this. Looks like all that is available is the Erse iron core inductors in 6.5mh from parts express.
Any thoughts on this would be helpful as I am in no way an expert on this stuff...
Jim
 
You mentioned the woofers were "bottoming out".
Do you mean the voice coil was banging on the magnet?
My ears would protest before that happened to me or perhaps you have a larger room than mine?

As to lowering the Iow pass to 122Hz, I don't think that mid bass couple does do too well below 200hz?
 
On very fast low bass it will bottom out. Like in the song Burning down the house by talking heads. (Though now they don't bottom out on that song with the 1100 caps in place) As chef free says in this thread it sounds like crickets. If you have the newer version with the 1100uf cap and 6.5mh coil than the low pass is 122htz. This is at a constant 5ohm load. The load will go up and down as the speakers are been used so the xo point may acually be 200htz as on the brochure for these speakers.
Jim
 
I am not trying to alter these from what the qls1 is. Just trying to figure out what is different in the xo from the older ones (black front) to the newer (walnut front) and make those changes. As far as I can tell this cap and choke difference on the 4ohm woofer coil is all. The woofers bottom out very easy with the way they were and I don't think I could put up with it. Others have noted this problem on this and other sites. The last thing I want to do when I am relaxing is worry about what my stereo is doing. The way they are now they will still occasionally bottom out before I think they should. My rs2.5 never bottoms out and will loosen the joint compound the walls. They have superior bass as far as I can tell. Not as low but tighter and it will hit you in the chest harder. The qls1 is superior in every other way though. Like many have said the cabinet volume may be too big for that single woofer. I have took out the pink insulation and replaced it with poly fill. This seemed to help as well. When I replace the 6.5 coils I will touch base again here.
Jim
 
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If all the drivers are the same as well as the interior cabinet volume, I see no reason not to update the xover as you want to do.
I have the 2.5s and the bass is very good but i think the QLS-1 is better:)
I must add that I'm using the 2.5 type Watkins in my QLS:idea:
How much polyfill did you put in ,as you know, the more polyfill added will increase the cabinet volume(from what I've read).
 
Thanks for your help and responses tubed. I have tried my other woofers in the qls1 while the others were getting fixed and they sound about the same. The poly fill was used because the pink insulation got pretty funky. I measured it out and put equal amounts in both. Stuffed pretty good like the other Infinitys I have but not jammed I'm not saying the qls1 lacks bass. It has it in spades. I think I need a little more time in front of them and maybe move them around a little. When I hook my real time analyzer to them they have the flatest response I ever got do to the adjustability of the qls1 crossover. It's really nice how you can turn the tweeters, mids and coupler off. You can just listen to say the tweeters or just the mids and listen for problems in their response.

I'd say where I like the rs2.5 better in the bass department is electronic type music like Frou Frou and the like. Rock and roll is a lot of fun with them as well.

Since I had that problem develope maybe I'm a little more critical of the bass in the qls1. Right now I have Chicago Transit Authority at near concert level and they are just cruising along as if they aren't even there. Truly an amazing speaker system.
Jim
 
When I hook my real time analyzer to them they have the flatest response I ever got do to the adjustability of the qls1 crossover. It's really nice how you can turn the tweeters, mids and coupler off. You can just listen to say the tweeters or just the mids and listen for problems in their response.Jim

What do you have the pots set to? Rears on or off? What about the high, mid, low tweeter crossover?
 
When the response is the flattest the tweeters are set around 3 o'clock, mids around 2, mid bass around 2 as well. Rear tweeters on. Tweeter crossover plug is on the middle setting. While this is flat I still turn the mids to around twelve to my liking. Midrange always seems a little hot in my room.
Jim
 
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