New Design QLS-1

[wwiztab]

I'm ready to begin building a modified version of the QLS-1. I have the original Watkins woofers, the original rear Emits and the original passive crossovers. Here is what I propose for the tweeters and mids.

Instead of the original rectangle emits I have 6 of the regular round emits per side (not emit K's).

Instead of the original soft domes I plan to use 6 or 4 per side of these: http://www.parts-express.com/pe/showdetl.cfm?partnumber=287-025

Instead of the original midbass coupler I plan to use these: http://www.parts-express.com/pe/showdetl.cfm?partnumber=287-032

I will add pictures of my drawings of the enclosure as I will model the front panel after the IRS, just with a woofer and mid bass and not as big. I will build the enclosure so the woofer has the same cubic feet as the QLS-1.

Any thoughts or suggestions is very much welcome. I have not purchased the mid-range or mid bass speakers yet. Please let me know if you think I should use something else. I don't have an endless supply of cash for these either, so please keep that in mind. Thanks

 

[wwiztab]

Here's a picture of the emits wired to keep them around 5 ohms. Can somebody let me know which crossover software is easiest to use. Since I'll have to rebuild 3 parts of the original x-over for the new drivers.

 

[elnaldo]

Speaker workshop is a very complete speaker design suite. But you need the freq response and impedance graphs for the drivers to do accurate calculations.

To do measurements, I think ARTA suite is quite easy to use. You can measure frequency and impedance easily with some basic measurement tools

If you just want to approximate or shift some crossover point of your actual crossovers, you can use some on-line calculators.

But looking at the kind of work you are facing, I would download and start learning to use that Speaker Workshop and Arta software at least...

For the mid-bass coupler, I'd get an used one and keep it original... 1 thing less to modify..

 

[wwiztab]

Thanks Enaldo.

Now since I have not seen a pair in person, can someone explain the mid bass coupler port? Is it just a direct front to back port that surrounds the driver? Cardboard I would assume. A picture of the inside would help explain the design of it.

Also, I have 167cm/65.75" x 38cm/15" x 45cm/17.75". Which one is the width and depth? Is it 1" material or 3/4"?

Just purchased a pair of the Dahlquist mid bass on the bay.

 

[cdfac]

if you can, put the midbass higher than in the original QLS1. i always thought that the sound changed too much from sitting down to standing up.

 

[elnaldo]

http://www.infinity-classics.de/mod...ne-Source-QLS-1/body_quantum_line_source.html

Looking at the pict , from the woofer width you can deduce the size...

 

[tubed]

When I listen to the QLS-1, I always wonder what it would sound like with a nice larger driver for the midbass coupler. Perhaps something along the lines of this 5.5" SEAS...or perhaps something even larger around 6.5"
http://www.madisoundspeakerstore.co...ige-mca15rcy-h1262-5.5-coated-paper-midrange/

 

[StimpyWan]

Maybe even try the RS 2.5" DOME, used in the 3A/B, 4B, 5/B, and 6B. Keep everything in the Infinity 'Family'. Plus, you could model your crossovers from those speakers. Schematics are available on infinity.classics.de

http://infinity-classics.de/models/Reference-series-1+b-2-10+A+B-1981-86/index-Reference.htm

And I agree with the others, use a larger midbass coupler. Even consider mounting it centered, to the inside of the mid/tweeter array...

Good Luck!

 

[jimreeves]

My main concern is the Morel middomes you're suggesting, 90db sensitivity is quite high and would probably require some padding to bring the output down to match the midbass and bass output.
Cabinets are 15" deep and 18" wide, 1" thick, except for the 7" high, 18" x 18" base that houses the crossover.
The midbass transmission tube is approx. 5 1/2" diameter cardboard and vents straight out the back. It's stuffed with fiberglass or polyfil to suit.

 

[wwiztab]

Jim, when you say padding, what do you mean? Would a potentiometer help with that? I see the Dayton and Tang Band are also close to 90db sensitivity.


If I did use the Infinity Poly domes like StimpyWan suggested, does anyone know what the sensitivity is of those? I do have an extra pair in storage. I just don't have the software yet to take that measurement.

Does anybody else know of another company building a soft dome mid?

 

[jimreeves]

I mean a fixed L-Pad. Since I don't think anyone knows for sure what the sensitivity of the original Peerless middomes is (anyone?), you would likely have to try several different L-Pad configurations during the 'voicing' phase of your build. Non-inductive resistors are pretty cheap at partsexpress.

http://ccs.exl.info/calc_cr.html

Plus we can't say what the sensitivity of the Emits you'll be using is either, and you'll be using 6 in front instead of 8 per cabinet, so the series~parallel impedance will be different.

None of that means they won't work or sound good, they'll just be different.

The overall sensitivity of the QLS is listed as 81db/1W/1M on Claus's website.

 

[dumptruck]

That's a pretty advanced crossover design task you've set out for yourself, to say the least.

 

[elnaldo]

Some more options in this 2010 thread:


Substitute Mids for Quantum series

 

[wwiztab]

So I ended up taking your advice Stimpy Wan. I've got 2 pairs of polydomes coming from the bay. I already have a pair so I just need another pair and I'm set. Somebody on the bay has a pair but wants way too much, I'll wait it out.

I should be able to put two each in series then parallel the two pair together and use the crossover design from one of those "B" series speakers.

 

[wwiztab]

Can somebody give me the measurement from the floor to the center of the woofer on their QLS-1 please. I thought about moving it up a little higher any thoughts about why I should or shouldn't?

Thanks for everyone's thoughts and suggestions so far.

 

[jimreeves]

My older, black baffle QLS's have the woofer mounted 16 1/2" above the floor to center. It may be different with later models with veneer baffles. Shouldn't make much difference how high you mount yours. Mine also have the 1 1/4" baffle extensions, later models have less.

 

[audiomagnate]

I'm ready to begin building a modified version of the QLS-1. I have the original Watkins woofers, the original rear Emits and the original passive crossovers. Here is what I propose for the tweeters and mids.

Instead of the original rectangle emits I have 6 of the regular round emits per side (not emit K's).

Instead of the original soft domes I plan to use 6 or 4 per side of these: http://www.parts-express.com/pe/showdetl.cfm?partnumber=287-025

Instead of the original midbass coupler I plan to use these: http://www.parts-express.com/pe/showdetl.cfm?partnumber=287-032

I will add pictures of my drawings of the enclosure as I will model the front panel after the IRS, just with a woofer and mid bass and not as big. I will build the enclosure so the woofer has the same cubic feet as the QLS-1.

Any thoughts or suggestions is very much welcome. I have not purchased the mid-range or mid bass speakers yet. Please let me know if you think I should use something else. I don't have an endless supply of cash for these either, so please keep that in mind. Thanks

Do you have the original cabinets or are you starting from scratch with just a few odds and ends from the originals?

 

[wwiztab]

No I DO NOT have the original cabinets. I now have original Watkins in gray poly, the original midbass (Dahlquist), and the original crossover system. I will now be using 8 of the round emits from the majority of the other models (not kappa series) and 6 of the Infinity polydome soft dome midrange drivers (not the kappa series).

 

[StimpyWan]

Cool! Thanks. But, now it's my fault, if the design doesn't work!

Also, 3 polydomes in each cabinet? Just curious if you're still trying to do a QLS-1 in spirit, or something a bit simpler? With what you have now, you could already bang out a Quantum 2.

Maybe build a bass (midbass) enclosure, and use that for a foundation. Build a dome/tweeter wing, and expand it as you go, adding additional domes as required/desired. Maybe similar to the original RS II.

http://infinity-classics.de/models/Reference-series-1+b-2-10+A+B-1981-86/index-Reference.htm

Since the domes and tweeters don't really need an enclosure, you could build a wing, like the RS II, and mount it to your bass module, so that it could be removable for design upgrades. Heck, mount the Watkins woofer, and midbass one above the other, then the wing could house the 3 dome mids, side by side with 3 emits. And a 4th emit facing the rear, for added ambiance...

I even saw a custom RS II, that had the center cone mid replaced with a RS dome. The original upper and lower cone mids were still in place. And due to the staggered crossover points used in the RS II, crossover tweaks probably weren't even needed. You could do something like that, with a single Watkins woofers in place of the dual 10" woofers... Just depends on you, and how much of a line-source you want your design to be...

Good Luck! :thmbsp:

So I ended up taking your advice Stimpy Wan. I've got 2 pairs of polydomes coming from the bay. I already have a pair so I just need another pair and I'm set. Somebody on the bay has a pair but wants way too much, I'll wait it out.

I should be able to put two each in series then parallel the two pair together and use the crossover design from one of those "B" series speakers.

 

[wwiztab]

Here's my first rough drawing. As you can see I will be using 8 emits and 6 polydomes per side. Once I build the cabinets I'll play with the location of the drivers to make it look symmetrical, but this gives everyone the idea.

The front will actually be wider than the enclosure and I'll probably use rosewood to build it. This keeps me from having to veneer the entire cabinet yet makes it look more like a nice piece of furniture.

The bottom rectangle is the fuse and all driver adjustment pots and rear tweeter on and off. I could never figure out why they put those on the back. Kind of a pain to have to reach behind to adjust them. I have a pair of RS Monitors and like the front location.