Single Driver Center Channel

[fuzz092888]

Cool! But, did you work out?

For 20 whole minutes

Not really a workout, but at least I can cross it off the list.

 

[TLS Guy]

Well I got it assembled today and I just got it hooked up. So I'm doing my demoing as I type this. So far so good. It sure is ugly, but hopefully I'll figure out how to use my HVLP guns and get it painted.

You need to make a speaker grill right away, or that fragile cone will be a gonner in no time.

 

[fuzz092888]

What do you think about a metal grill, or should I stick with a cloth grill?

 

[lsiberian]

A cloth grill should be easier to make and would match your side speakers better, but if you have cats then definitely don't go that route. I'd hate to see anything hurt that driver.

 

[Adam]

I'd hate to see anything hurt that driver.

Well, when a cat gets close to it - stop watching the webcam.

 

[lsiberian]

Well, when a cat gets close to it - stop watching the webcam.

Thankfully my cat hasn't taken to my speakers, but there is a fear. A fear that leads to an opportunity to upgrade, but a fear nonetheless.

 

[fuzz092888]

No cats, no nothing to really damage the driver except humans. I'm still trying to figure out a paint booth, or least get a sunny, non-windy day. This weekend might be that time where I can at least do a test spray.

So far I've been watching TV all day and I watched most of The Hobbit last night to do some testing. I have to say that to my ears, it sounds as good as the SongCenter. Even if I don't get around to test spraying this weekend, I'm going to hook up my Adcom speaker selector so that I can A/B them.

This driver is really something else. $100 for the driver, a cabinet made from scrap MDF, and $10 for binding posts and so far it is holding its own against the $1800 Salk made Songcenter with custom RAAL tweeter. Nothing for nothing, but I came in heavily biased as well. I love my Songcenter and the quality of the construction combined with high quality drivers just tickles me the right way. Plus it was made with a few custom tweaks that I asked for. I'm a mediocre wood worker, so the other speaker obviously looks rough, but I'll be darned if it doesn't sound excellent.

 

[TLS Guy]

What do you think about a metal grill, or should I stick with a cloth grill?

A cloth grill for sure. Metal grills can resonate.

 

[TLS Guy]

No cats, no nothing to really damage the driver except humans. I'm still trying to figure out a paint booth, or least get a sunny, non-windy day. This weekend might be that time where I can at least do a test spray.

So far I've been watching TV all day and I watched most of The Hobbit last night to do some testing. I have to say that to my ears, it sounds as good as the SongCenter. Even if I don't get around to test spraying this weekend, I'm going to hook up my Adcom speaker selector so that I can A/B them.

This driver is really something else. $100 for the driver, a cabinet made from scrap MDF, and $10 for binding posts and so far it is holding its own against the $1800 Salk made Songcenter with custom RAAL tweeter. Nothing for nothing, but I came in heavily biased as well. I love my Songcenter and the quality of the construction combined with high quality drivers just tickles me the right way. Plus it was made with a few custom tweaks that I asked for. I'm a mediocre wood worker, so the other speaker obviously looks rough, but I'll be darned if it doesn't sound excellent.

Yes, they are an incredible driver. Overall I think they are the only full range driver that is really any good. You have yours in a small box. Loaded in a TL, the bass output from these little drivers is astonishing. They have a deep bass down into the low forties in a TL, that is non resonant and they are capable of truly coherent transparent reproduction.

I sold you that driver at 25% above selling price in the early seventies. In today's dollars that driver would cost $410.

 

[fuzz092888]

Yes, they are an incredible driver. Overall I think they are the only full range driver that is really any good. You have yours in a small box. Loaded in a TL, the bass output from these little drivers is astonishing. They have a deep bass down into the low forties in a TL, that is non resonant and they are capable of truly coherent transparent reproduction.

I sold you that driver at 25% above selling price in the early seventies. In today's dollars that driver would cost $410.

That makes sense. I actually found a build someone did where they had the JX92S in a TL and said it sounded really good. I have no doubt the original would sound at least as good. That's a pretty hefty sum and the new ones aren't exactly cheap either, especially after shipping. I'd love to see more builds using these drivers in a variety of configurations.

 

[fuzz092888]

I haven't done a proper A/B scenario yet, but I at least got it setup with the speaker selector. I've been bouncing back and forth all night and definitely detect some differences.

 

[STRONGBADF1]

How's the efficiency? I would think it would struggle to keep up with your mains if pushed too hard.

Oh yea, Those bears are killing me...and is that your knee or should you be wearing a hat?

 

[TLS Guy]

How's the efficiency? I would think it would struggle to keep up with your mains if pushed too hard.

Oh yea, Those bears are killing me...and is that your knee or should you be wearing a hat?

I sent him a 4 ohm driver, the sensitivity is 92 db 2.83 volts 1 meter. There are no crossover components, so that is what he will get.

Much to my surprise, the little JW module keeps up with the mains very well in my Eagan rig. I have to say somewhat to my surprise. But crossed over at 90 Hz it is capable of pretty high output. It is an under slung voice coil deep in a large magnet gap and the cone being aluminum also gets the heat away. The suspension gives it a large linear xmax.

It has always been loud bass that is the destroyer of these drivers.

I have put together huge auditorium rigs in years past with these drivers. Crossed at 400 or 500 Hz to 15" drivers in huge back loaded horns. I used to use 8 or 16 drivers a side above the bass horns as a vertical array line source. Very high spl was possible. Better than Altec horns of the day.

Quite honestly I have never heard better fidelity in large spaces than those rigs. They really were astonishing.

The one driver keeps up well in this rig and Audyssey sets the level of the 4" driver 5.5 db below the mains!

 

[fuzz092888]

How's the efficiency? I would think it would struggle to keep up with your mains if pushed too hard.

Oh yea, Those bears are killing me...and is that your knee or should you be wearing a hat?

Surprisingly, I measured the songcenter as 2db louder than the Jordan Watts driver, which doesn't make sense based on the sensitivity Dr. Mark just gave. The songcenter is rated at 88db, but that might be with the dome tweeter version. However, I wouldn't expect it to gain 6db in sensitivity with the RAAL.

As for keeping up, I have it crossed at 120Hz and it keeps up just fine at just about any volume I care to listen to.

It gets worse. The mouths are magnetic and when you pull them apart and put them back together there's a little heart that glows.

 

[fuzz092888]

Mic-UMIK
Distance-1m
Smoothing-1/12
JW Module-Yellow
Salk-Green



Mic-ECM8000
Distance-1m
Smoothing-1/12
JW Module-Purple
Salk-Green

 

[TLS Guy]

Surprisingly, I measured the songcenter as 2db louder than the Jordan Watts driver, which doesn't make sense based on the sensitivity Dr. Mark just gave. The songcenter is rated at 88db, but that might be with the dome tweeter version. However, I wouldn't expect it to gain 6db in sensitivity with the RAAL.

As for keeping up, I have it crossed at 120Hz and it keeps up just fine at just about any volume I care to listen to.

It gets worse. The mouths are magnetic and when you pull them apart and put them back together there's a little heart that glows.

Sensitivities are always imprecise.

The sensitivity of those SEAS drivers is 87.5 db 2.83 Volts 1 meter. So two should have a sensitivity of 90.3 db. There will be loss from the crossover of probably a couple of db at the most, more likely 1.5 db. The sensitivity of the song towers should be at least 88.5 db 2.83 volts 1 meter.

The impedance curve of those woofers would make them 3 ohm for two woofers over a good deal of the midband.

I am using a four ohm module, sensitivity 88.75 db 2.83 volts 1 meter, and the four ohm should increase that by 3db. However the impedance rises for those modules at 500 Hz, so I almost certainly have over estimated the sensitivity of the 4 ohm module. So the four and eight ohm modules are likely quite close.

My main speakers have a sensitivity of 85 db 2.83 volts 1 meter. In the previous post I said that the JW was set at 5.5 db below the mains. I have just back to Eagan and checked the data, they are in fact set at 4 db below the mains, which would put an 8 ohm module at 89 db 1 watt 1 meter. So that agrees with measurements.

Where does Audyssey set your main/center levels?

 

[TLS Guy]

Mic-UMIK
Distance-1m
Smoothing-1/12
JW Module-Yellow
Salk-Green



Mic-ECM8000
Distance-1m
Smoothing-1/12
JW Module-Purple
Salk-Green

I can't believe how close those measurements are for a couple of speakers poles apart in design and concept.

By the way if you cross the JW at 90 Hz, you should have a perfect fourth order composite roll off at 90 Hz.

 

[fuzz092888]

I haven't run it with the JW module, but it sets the left/right at -5/-4 and the center at -2.5 with the Salk Center.

I changed the cross to 90, Audyssey originally set it to full range, and I had adjusted it to 120 I think.

I was really surprised at how similarly they measured. I'm just trying to figure out the roll off above 10Khz and what's causing it. Theoretically neither mic should be rolling off like that. Perhaps it's the soundcard in my computer.

 

[TLS Guy]

I haven't run it with the JW module, but it sets the left/right at -5/-4 and the center at -2.5 with the Salk Center.

I changed the cross to 90, Audyssey originally set it to full range, and I had adjusted it to 120 I think.

I was really surprised at how similarly they measured. I'm just trying to figure out the roll off above 10Khz and what's causing it. Theoretically neither mic should be rolling off like that. Perhaps it's the soundcard in my computer.

The JW does roll off on the top end, about 6db per octave starting just above 6 kHz. Better to roll off than rise.

 

[fuzz092888]

The JW does roll off on the top end, about 6db per octave starting just above 6 kHz. Better to roll off than rise.

Very true.

I just rechecked the measurements and the measurement is telling me that from 6khz-12khz it is down 13db. From 12-20 the measurement is down 31db.

The Songcenter measurement is definitely off, since Dennis Murphy checked it and made sure it was pretty darn close to spec before I received it. I guess I have some experimentation to do.