Custom ESL using quest panels

[Brandon Hartwick]

As some of you know, for the last several months I've been developing a hybrid ESL speaker around Quest panels, I decided to move this to its own thread going forward. This speaker will fit somewhere in between the 13A and 15A for size and use the same panel over woofer design.

Construction
The main construction of this speaker will be laser cut 3/16" steel, including the woofer enclosure. The woofer enclosure is 2 cubic feet sealed, it uses 5 internal ribs that wrap all 4 sides for bracing. The ESL panel is supported by steel uprights that are tied together at the top, the panel itself actually adds quite a bit of strength to the whole part.

Drivers & Components
The ESL panels are from the original Martin Logan Quest, these are only a little bit smaller than those used in the new 15A speakers.

For the bass sections I will be using the Sovereign Pro 12-500 pro audio woofers from Fane Audio. I chose these for their low moving mass and very good frequency response in the 100-500HZ range, they also cost under $350 Canadian for the pair.

I'm using the original OEM power supplies with a pair of MULTICOMP PRO VTX-146-050-106 toroidal transformers wired together to get the correct winding ratio. Original transformers from Martin Logan are no longer available for this panel. Below is the wiring instructions courtesy of Jazzman here on the forum, he also was the one to suggest using these trannies so all credit goes to him.

Crossovers
The entire speaker will be ran off a Dayton 4X8 DSP unit, I will not be using any form of passive crossovers on the woofer or the panel. I will probably be crossing the ELS panel over with a 350HZ highpass @ 24BD/octave and the woofer will be bandpassed at 350hz and 60hz. The lower bass extension from 60hz and down will be handled by a corner loaded line array of 12" subwoofers.

Testing and development
I brought the panels and power supplies home to give everything a thorough test run with real power and real music. I wanted to do this since I got these panels second hand and wanted to be 100% confident there were no hidden issues. I hooked them up to my Jeff Rowland Model 1 (50W & stable into 2 ohm) and played music throughout the evening while using the Aerius 8" woofers for a little bass support. The panels worked flawlessly as expected and the aftermarket transformers worked great.

With a solid test run successful I'll get the rest of the parts sent to the laser cutter to complete the metalwork of the speaker. The rest of the steel might take a little while because I won't be sending it to the laser cutter until I have another large order from work to go at the same time.

I'll continue to update this in the coming weeks. Right now I'm extremely busy with work so I'm not sure when more progress will be made. If anyone has questions ask away, we're all here to learn.

 

[Jazzman53]

Brandon,
Congrats on a great project!

I have no reservations about recommending the tandem pair of those inexpensive 50VA toroidal transformers. I've been using them for many years, driving them with multi-hundred watt amps with no problems. I especially like the pristine highs.

I should point out that the tandem 50VA toroid setup is great for hybrid panels operating above 250Hz but there isn't enough iron in there to accommodate full range use. Feeding them a full range signal at high power would likely drive them into saturation and possibly smoke the amplifier. Most ML's are hybrids anyway so there would be no problem!

Nice work, sir!

 

[Brandon Hartwick]

Brandon,
Congrats on a great project!

I have no reservations about recommending the tandem pair of those inexpensive 50VA toroidal transformers. I've been using them for many years, driving them with multi-hundred watt amps with no problems. I especially like the pristine highs.

I should point out that the tandem 50VA toroid setup is great for hybrid panels operating above 250Hz but there isn't enough iron in there to accommodate full range use. Feeding them a full range signal at high power would likely drive them into saturation and possibly smoke the amplifier. Most ML's are hybrids anyway so there would be no problem!

Nice work, sir!

I owe you many cases of beer good sir, without transformer options like this the project wouldn't have been possible.

I plan on an X-over point of around 350hz so killing transformers and amps shouldn't be an issue. But let's say someone happens to come across a large full range panel like the CLS, could you just up size the transformers? Just curious...

Anyway, I appreciate the kind words. I think this will be a very cool project when it's done. It's funny because I actually have no need for these speakers, they actually might not even fit into my apartment very well. But due to interesting circumstances I got a 2yr old set of Quest panels and electronics for cheap. I love unique audio gear and decided these needed to be used for something cool, here we are.

 

[Jazzman53]

I owe you many cases of beer good sir, without transformer options like this the project wouldn't have been possible.

I plan on an X-over point of around 350hz so killing transformers and amps shouldn't be an issue. But let's say someone happens to come across a large full range panel like the CLS, could you just up size the transformers? Just curious...

Anyway, I appreciate the kind words. I think this will be a very cool project when it's done. It's funny because I actually have no need for these speakers, they actually might not even fit into my apartment very well. But due to interesting circumstances I got a 2yr old set of Quest panels and electronics for cheap. I love unique audio gear and decided these needed to be used for something cool, here we are.

To power a full range ESL you could just size up the VA rating but a better option would be to use six of the 50VA toroids per speaker, wired parallel on the input side and series/parallel on the output side, as opposed to two larger transformer wired in series on the output side. The series/parallel arrangement on the output side would cancel some of the winding capacitance that you would get with two transformers in series/only. Also; you would need to choose appropriate voltage ratings -- maybe 230V/9V or 230/12V rather than 230V/6V or whatever adds up to a step up ratio around 115:1 to 130:1. Higher ratios (150:1) would give higher output but lower ratio's give better treble response.

 

[JonFo]

Excellent work Brandon! Good to see them operational.

I hope the rest of it comes together well. Tuning the XO is fun, and I'll chime in more during that phase. If not already familiar with using REW, might want to start watching how-to videos and playing around with it. To me, REW is the audio equivalent of a carpenter's tape measure, can't do a build without it.

 

[Brandon Hartwick]

Excellent work Brandon! Good to see them operational.

I hope the rest of it comes together well. Tuning the XO is fun, and I'll chime in more during that phase. If not already familiar with using REW, might want to start watching how-to videos and playing around with it. To me, REW is the audio equivalent of a carpenter's tape measure, can't do a build without it.

I haven't actually played with REW yet to setup DSP. When I went Active on my Aerius speakers i didn't really need DSP, but I'm sure with these larger speakers I will. I'll have to watch some YouTube videos, I already have a microphone and I think I just need an XLR cable and I can take some measurements.

 

[Brandon Hartwick]

All the metalwork has been sent out to the laser cutter this afternoon for quote so I should have all the parts in 3 weeks or so. I plan on starting the construction on this over Christmas, maybe I'll bring a welder home with me lol.

Lots of cool stuff to come shortly!

 

[Brad225]

Excellent work Brandon. I can't wait to hear your comments when they are complete.

 

[Brandon Hartwick]

Excellent work Brandon. I can't wait to hear your comments when they are complete.

If this all works out well I will make a simplified version of the cut files available to the public. Then anyone with a welder should be able to make something like this.

 

[Brandon Hartwick]

FINALLY, I have an update for everyone.

It looks like Christmas came early and all my parts have arrived from the laser cutter. I have done a rough test fit of the woofer enclosures and the fitment is spot on. There's a ton of bracing that needs to go inside these boxes but that's a job for next week I think.

Many more updates to come in the next few weeks.

 

[Russr]

How thick are those plates? What are your plans for bracing?
Oh, and "cool as hell", BTW!!!

 

[Brandon Hartwick]

How thick are those plates? What are your plans for bracing?
Oh, and "cool as hell", BTW!!!

For bracing, each enclosure has 5 plates that are evenly spaced down the length of them, the front most set of bracing has a larger center opening to accomodate the huge magnets on the woofers. The body of the enclosure is made of 3/16" plates with a doubled up front baffle, each speaker will probably weigh north of 200lb I'd guestimate.

 

[JonFo]

each speaker will probably weigh north of 200lb I'd guestimate

Truly "Heavy Metal" speakers.

Nice progress Brandon.

 

[Brandon Hartwick]

OH BABY

This is starting to get very exciting. So far everything fits great other than my internal cabinet bracing, it looks like I messed up the size of the slots so a little modification will be required before going further. That's next week's job since I have some off time after Christmas.

 

[Duke]

Pretty

 

[Jazzman53]

Just wondering if you're a heavy metal fan

 

[Russr]

It's really taking me a while to wrap my head around this - not the idea or the amazing execution of your project.. I spent years around folks who would analyze & build enclosures, tune environments, etc. My love for MLs started at that time when I got my mitts on a client's pair in the late 80's. At the time, we were working on all kinds of cool equipment, and I got into thing like Linn Isobariks, Klipschhorns, Bose 901's, etc. While I haven't done anything like your project in a long, long time, all my "instincts" are based on simple, 3-D "chunks" of material (like wood, MDF, Resins, etc.). I'm having difficulty thinking about an enclosure with walls/baffles/bracing that is relative so thin (though rigid). Really fascinated to see how this turns out. Do you have the ability to generate response curves once you have them up & running?

And Happy Holidays! Hope you don't spend TOO much time in the shop instead of around the tree!

 

[lowheat]

OH BABY

This is starting to get very exciting. So far everything fits great other than my internal cabinet bracing, it looks like I messed up the size of the slots so a little modification will be required before going further. That's next week's job since I have some off time after Christmas.

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So, how much to ship?
Just kidding.
Nice work.

 

[ih82lose]

I’d love to learn more about the aftermarket transformers you used. I have a spare pair of quests with one panel having a bad transformer. ML no longer supplies the part, so I need to go DIY with it to repair it, but have not seen any documentation on how. Would love to learn how you are driving the panels with aftermarket electronics if you’d be willing to share. Thanks for the inspiration!

 

[Brandon Hartwick]

Just wondering if you're a heavy metal fan

Funny you mention that, I'm a huge metal/metalcore fan, even some deathcore such as Lorna Shore has really got my attention lately. Electrostatic speakers just show off technical side of extreme music so well it just grabs me and sucks me right in, just close your eyes and you're surrounded by an assault of sound.