New SongTower QWT launch

jsalk · « **on:** 21 Jul 2007, 04:59 pm »

Well, we've tossed around what seemed like hundreds of names http://www.audiocircle.com/index.php?topic=40820.0 and we're finally ready to launch Dennis Murphy's latest design - the SongTower QWT.

Here are some pictures of the first production pair shipped...

Here they are with the grills installed...

And a close-up of the baffle area...

For those not familiar with the project, here is some information previously posted...

The SongTower QWT is an MTM design using a MLQW Transmission Line cabinet based on the pioneering work of Martin King. This transmission line cabinet allows the floor-standing speaker to exhibit greater bass extension than a ported design would normally allow.

This design is the end result of a year-long project to develop a very affordable (under $1500) speaker that
1) is wide range, with useful bass response to at least 40 Hz;
2) has a small enough footprint to allow cabinet dimensions with high SAF; and,
3) is sensitive enough to be compatible with a wide range of amplifiers.

Traditional 3-ways would almost certainly fail at least one of the last two requirements. Traditional 2-way bookshelf designs would require a large woofer that might not produce the best possible performance in the upper midrange, and would also require stand-mounting (low SAF).

The solution was to use two high quality 5" drivers optimally suited to Martin King's MLQW transmission line cabinet design, mated to a high quality tweeter.

The Seas CA15 woofers were an obvious choice to perform bass duties, due to their appropriate electrical and mechanical parameters and extremely smooth and extended response at higher frequencies.

The Hiquphon 0W2, which is a more sensitive version of the 0W1 used in Dennis' CA0W1 2-way design, was perfectly suited for the design, since it is sensitive enough to keep up with twin CA15 woofers and provides almost ruler-flat response and extremely broad dispersion. In addition, this tweeter is rugged enough to allow a fairly low crossover frequency with room to spare.

Since the 0W2 is so expensive, an alternative crossover was also developed using the Vifa dx19 3/4" tweeter. Although this unit is not quite as smooth as the 0W2, it too can operate safely at low crossover frequencies and sounds very much like the 0W2.

In either configuration, the sensitivity of the MTM is conservatively rated at 88 dB, and can play a 38 Hz tone at high enough drive levels to set off rattles from loose objects in a typical room.

The MLQW transmission line cabinets are a sleek 8" wide, 11.25" deep and 44.5" tall (not counting plinths and spikes) and are rear ported.

Here is a frequency response plot showing its near ruler-flat response...

Many speaker companies publish FR plots that are 15-degrees off-axis. Here's one that shows the designs response at 60 degrees off-axis!

We feel these speakers set a new sound quality standard for a speaker system priced under $1500 and are now ready to accept orders for this new design.

The SongTower QWT's are priced at $1495 per pair and are available in walnut, cherry, maple and black satin finishes. And for a limited time, the honey locust finish shown in the above photos will also be available (until our current stock of that veneer is exhausted.

In the very near future, a "SongCenter," "SongSurrounds" and a "SongSub" will also be available to round out this series of speakers.

Thanks to everyone who provided input into this project. Your help. support and encouragement are greatly appreciated by Dennis and me.

- Jim

PS: Orders submitted during the remainder of July and all of August will recieve a free SongTower t-shirt (not much, but it is free) as our way of saying thanks for helping us launch this new model.

fsimms · « **Reply #1 on:** 21 Jul 2007, 05:28 pm »

These are coming to me!

DHL says they will arrive Tuesday. I will let you know how they compare to my HT1's after I have had a chance to play with them.

Toka · « **Reply #2 on:** 21 Jul 2007, 05:48 pm »

Looks even better than before! Good choice on the name as well. Man oh man, why do I live in a condo...

jsalk · « **Reply #3 on:** 21 Jul 2007, 06:44 pm »

I am guilty of the sin of omission. In my haste to post this information, I forgot to acknowledge one very important contribution to the SongTower's design effort.

As indicated above, the cabinet design is based on the pioneering work of Martin King. But Martin King's worksheets are of little value without proper implementation.

Paul Kittinger has mastered the use of Martin King's Mathcad worksheets to design numerous TL cabinets. His specific cabinet design for this model was instrumental in obtaining the SongTower's bass response. Without his contributions, Dennis Murphy could not have designed such a wonderful speaker.

Thanks, Paul. Sorry for the unintended omission.

- Jim

Big Red Machine · « **Reply #4 on:** 21 Jul 2007, 08:19 pm »

Who's the weiner of the "name the speaker" contest?

Got an extra pair for me to evaluate?

Nels Ferre · « **Reply #5 on:** 21 Jul 2007, 08:24 pm »

Quote from: Toka on 21 Jul 2007, 05:48 pm

Looks even better than before! Good choice on the name as well. Man oh man, why do I live in a condo...

I live in a condo...I'm not seeing the problem. My condo has cement subfloors and block construction behind the drywall though, so it is nearly soundproof. I never hear my neighbors, and they never hear me.

As an aside, Jim has promised me a review sample, so keep an eye out for that. The review pair will be finished in Honey Locust.

DMurphy · « **Reply #6 on:** 21 Jul 2007, 09:13 pm »

Let me just underscore Paul Kittinger's contribution. This speaker started out with a different transmission line design that was not based on Martin King's optimization procedure. All who heard it at DCDIY2006 loved the midrange and also thought the bass was impressive. But Paul was convinced we were only about half way there in the bass department, and insisted that much more was to be had if we followed Martin's calculations using mass loading (which is the "port" in re rear). I was dubious at first because the existing design seemed to be doing so well, but Paul, who is an expert with Martin's program, cranked the numbers and finally convinced me to have another cabinet made built to Paul's specs. Both my measurements and ears told me Paul was very right, and that's the cabinet Jim hopefully will be selling a lot of. One other point. I'm not sure Jim has settled on a price for the dx19 version, but it definitely will be even more affordable. This tweeter does require a little more crossover equalization than the 0W2, but I had a hard time telling them apart when I compared the final two versions of the speaker. So if money is tight, don't think the dx19 is a big or even little step down. It's a very tiny step.

DMurphy · « **Reply #7 on:** 21 Jul 2007, 09:16 pm »

Quote from: fsimms on 21 Jul 2007, 05:28 pm

These are coming to me! DHL says they will arrive Tuesday. I will let you know how they compare to my HT1's after I have had a chance to play with them.

That should make an interesting comparison. I've never been able to do it. My guess is that the midbass may seem a little more pronounced on the HT1. But play some music with real content in the low end, and I think you'll find the towers keeping up with the 7" Seas woofer, and perhaps delivering even cleaner deep bass.

jsalk · « **Reply #8 on:** 21 Jul 2007, 11:06 pm »

BRM -

Quote from: Big Red Machine on 21 Jul 2007, 08:19 pm

Who's the weiner of the "name the speaker" contest?

db Cooper came up with the name we eventually selected. However, everyone was a winner! Anyone who suggested a name qualifies for a free SongTower t-shirt as our way of saying thanks.

Quote

Got an extra pair for me to evaluate?

Not today. But we'll be cranking them out in the next couple of weeks and as soon as we have a pair to spare, you are welcome to give them a spin.

- Jim

avahifi · « **Reply #9 on:** 22 Jul 2007, 02:09 am »

Obvious question: How do they compare to the Veracity QWs that are twice as expensive?

Regards,

Frank Van Alstine.

P.S. I love both sets of my HT3s.

DMurphy · « **Reply #10 on:** 22 Jul 2007, 02:56 am »

"Obvious question: How do they compare to the Veracity QWs that are twice as expensive?"

I wish I could answer that one. Unfortunately, if I had to keep every design I've done in inventory, I would have to buy another house in area code 20816. And that's not going to happen on a government economist's salary. My best guess is that the Veracity will go about 6 Hz lower in the bass departent, and will have a slightly airier sound at the very top. The midrange is anyone's guess. It's hard to beat the W18, but the smaller diameter of the CA15's might provide a slightly more focused sound. But I'm not sure. Perhaps Frank would like to purchase both designs and report back? That's the ticket--everyone knows you've sold a $billion worth of those amps. Or should have. Cheers.

marvda1 · « **Reply #11 on:** 22 Jul 2007, 03:04 am »

dennis, i'll keep some of them for ya!!

Paul K. · « **Reply #12 on:** 22 Jul 2007, 02:09 pm »

I want to thank both Jim Salk and Dennis Murphy for their kind comments and recognition of my contribution to the SongTowers. I'm not entirely comfortable with the "expert" label Dennis gave me but it's nice he thinks that much of my input. Of course my part in the project was rather small when compared to the years of work Martin King has devoted to providing hobbyists with his marvelous worksheets for designing and modeling TLs, taking all of the mystery out and debunking the many myths. And, no speaker system is going to be very good unless the crossover is properly designed, and Dennis is simply an exceptional crossover designer. Now if we could just get him to build his own cabinets!

Jim and Dennis, thanks a bunch

ctviggen · « **Reply #13 on:** 22 Jul 2007, 02:37 pm »

Quote from: DMurphy on 22 Jul 2007, 02:56 am

"Obvious question: How do they compare to the Veracity QWs that are twice as expensive?"

I wish I could answer that one. Unfortunately, if I had to keep every design I've done in inventory, I would have to buy another house in area code 20816. And that's not going to happen on a government economist's salary.

You're a government economist and a crossover designer? Is the former your "day job"?

DMurphy · « **Reply #14 on:** 22 Jul 2007, 03:21 pm »

I sure hope so. Not going to make it as a crossover designer, at least not at my current charge, which is zero. The only exception is the new MTM, which I do have a financial stake in. So better sprinkle on a few more grains of salt whenever I say anything positive about it.

Boybees · « **Reply #15 on:** 24 Jul 2007, 08:23 pm »

Congratulations - beautiful design. Would it be possible to post some pix of the back of the speaker?

jsalk · « **Reply #16 on:** 24 Jul 2007, 09:01 pm »

Boybees -

Quote from: Boybees on 24 Jul 2007, 08:23 pm

Congratulations - beautiful design. Would it be possible to post some pix of the back of the speaker?

I'll try and remember to take some pics as we finish the next pair.

- Jim

tvyankee · « **Reply #17 on:** 25 Jul 2007, 01:24 pm »

Hello

If they are rear ported how far off the wall behind them do they need to be or does this not effect the sound that much?

Thanks

prpixel · « **Reply #18 on:** 25 Jul 2007, 06:22 pm »

Jim,

Are you manufacturing the cabinets yourself or outsourcing?

Thanks,

DMurphy · « **Reply #19 on:** 25 Jul 2007, 07:18 pm »

Jim is probably building cabinets, so I'll answer. We're not outsourcing--Jim has been working on a more efficient method of building cabnets in general, and the ST MTM in particular. So that's all Jim's handiwork. As for how far out they have to be placed, I would say 1-2 feet.