Would someone assist me with a calculation?

[homebuilder]

I'm looking for help from someone who has modeling software. I dont' have any capability to do that. I have a pair of Madisound Oak cabinets, with net about 3cf, sealed. They have the NHT 1259 woofer. I'd like to buy a couple of Jack Hidleys AR woofer he has one sale for $30. FS 19.8, QMS 4.09, Qes 0.216, QTS 0.205, VAS 269, CMS .000736, mms 87.8, BL 13.4, SPL 95.2, ZMAX 70.8, Sd 0.05070, XMAX 5.0, Hg 8.0, Hvc 18.0 Jack says they share the same frame, so should be a direct swap for the 1259. I'd like to know what performance I could get out of that. Also, what would result if you added a second AR woofer to each box to cancel out vibration from the other woofer?

I appreciate anyone who would take the time to answer this. I'm laid up right now with a couple of torn vertabrae, and need something to distract me from the injury. This sounds easy and fun.

[Richard Ellis]

I got some really small figures for a sealed system .87 cubic feet for .707 (Ideal), but your three cubic foot enclosure drives down the Qtc to less than .5 Toward the so-called "transient perfect" zone. (correction, the value in the calculation is in cubic feet)

_________________________________________________R ick....

[c2cthomas]

As JH sez on his website - they won't go as low.............

WinISD seems to agree

[homebuilder]

Thanks guys. What I'm looking for out of this idea is to be able to play the woofer higher than the 1259 goes. I'd like to get up to 300-400 hz. That 1259 in that Madisound cabinet is not bad sounding, but I'd rather build a new sub with a much larger (15" or 18") driver, or just sell the 1259s.

The AR woofers are so cheap I was hoping to use them with that box. What happens if I add the second woofer? I was thinking back to back.

Thanks!

[c2cthomas]

Donno about how high it goes - why not email JH??

Here is a link to his page - if you look below the AR12 he has a document linked but it only addresses the bass response........
NHT drivers and electronics surplus sale

[MCPete]

Originally Posted by homebuilder

I Also, what would result if you added a second AR woofer to each box to cancel out vibration from the other woofer?

Even though I'm fairly familiar with sealed systems, I haven't heard of the technique that you refer to for "canceling vibration". Would the AR woofer be active or passive? If active, driven in phase or out of phase with the other woofer? An isobaric arrangement reduces harmonic distortion, but not vibration, per se. Are you referring to vibration of the enclosure?

Originally Posted by homebuilder

What happens if I add the second woofer? I was thinking back to back.

Can you explain what you mean by back to back?

Sorry if I'm just an ignoramus.

-Pete

[Soundminded]

Originally Posted by homebuilder

I'm looking for help from someone who has modeling software. I dont' have any capability to do that. I have a pair of Madisound Oak cabinets, with net about 3cf, sealed. They have the NHT 1259 woofer. I'd like to buy a couple of Jack Hidleys AR woofer he has one sale for $30. FS 19.8, QMS 4.09, Qes 0.216, QTS 0.205, VAS 269, CMS .000736, mms 87.8, BL 13.4, SPL 95.2, ZMAX 70.8, Sd 0.05070, XMAX 5.0, Hg 8.0, Hvc 18.0 Jack says they share the same frame, so should be a direct swap for the 1259. I'd like to know what performance I could get out of that. Also, what would result if you added a second AR woofer to each box to cancel out vibration from the other woofer?

I appreciate anyone who would take the time to answer this. I'm laid up right now with a couple of torn vertabrae, and need something to distract me from the injury. This sounds easy and fun.

The NHT 1259 was actually manufactured by Tonegen. Tonegen became an outsource supplier to AR for its 12" acoustic suspension woofer late in the life of that driver's production which lasted about 30 years. The same basic design and performance of that woofer was the original version introduced with AR1 and AR1W in the mid 1950s and was used in AR3, 3a, 10pi, 11, 303, 58 and Teledyne 9 among others. It can be easily identified by its truncated (flat) sides although the cone and surround remain round so some call it an 11 inch woofer. If that is the woofer you are looking at, you're in luck. The only thing to be careful about is that if they are not early production units which used cloth surrounds but have foam surrounds those surrounds needed replacement at some time so be sure it has been done. The Xmax for that driver is much more than 5mm, more like 10 or 12, it was a long throw woofer. It also needs a tightly sealed enclosure line the 1259 and an amplifier that supplies a lot of power and is very stable with loads well below 4 ohms. If you wire two in parallel, you will need to take steps to keep the impedence high enough so that you don't blow up your amplifier. The Tonegen 1259 was sold by Madisound for about 160 dollars. Later there was a variant called the Madisound 1259 which they claimed was sufficiently different to merit a new model number. That driver was available as both 4 and 8 ohm versions with the 4 ohm version performing slightly better, at least on paper.

Luckily if the standard 12" AR driver is the driver you are talking about, all of the work has been done for you already and documented. It can be found in the library of The Classic Speaker Pages web site. All drawings and specifications for speakers like AR3a, how to repair and restore them are there for you, all you have to do is copy them. The speaker has the advantage of having a paper cone, not a plastic one like Tonegen's which allows it to be crossed over without problem at 525 or 575 hz in AR3a and about half the Vas of Tonegen1259. BTW, Stereophile's review of NHT 3.3 designed by Ken Kantor who worked for AR (he designed the 303, a modernized version of AR3a) showed it to produce bass second to none. It can be used in a 3 way system if it is crossed over low enough. 3.3 probably refers to the internal volume in cubic feet. The AR 12" woofer requires something like 1 1/2 cu feet and about 1 1/2 pounds of fiberglass stuffing (don't know what amount of the synthetic stuff that corresponds to.) The amount of stuffing is critical. Two AR 12" woofers were mounted facing outward on each side in AR9 producing outstanding bass at least as good as NHT 3.3. They are wired in parallel and in phase. These speakers fall off at only 12 db per octave and so their output is equalizable for at least an octave. If you use the parallel arrangement, be sure to copy the woofer section of the crossover network or use two amplifiers so you don't blow your amplifier up. The crossover network in AR9 keeps them at 4 ohms or more. They will still cause a typical 6 ohm HT receiver to shut down to protect itself so a cheapo amplifier is not in the cards for it.

The standard AR 12" woofer has a system F3 of 42 hz, AR9 of 28 hz. Both have a Q of .707 as their design goal. Both have exceptionally low THD generally in the range of 5% or less down to their lowest frequencies.

Good luck on your project.

[homebuilder]

Soundminded: thank you for that information. It is very helpful. First, the 1259 I have are the Tonegen 1259 you describe. I live close to Madisound, and recently went to see Larry to see if they had a couple of the older style ones laying around. They do not. As you said, the new one is different, but pretty similar.

The AR woofer that Jack is selling was for the AR9, if I recall from the many posts made for that article. Here is my dilemma...I have a bunch of stuff laying around; I want to use that Madisound cabinet if possible, because it is a mediocre sub. The cabinet should be braced better. For my experiments, I need it to go to at least 300hz, but 400-500 would be better.

According to Jack, the one he is selling is the same frame, but has less extension. It does have 6 db more output than the 1259, but not much xmax. My thought was to remove the 1259, and sell them. Put in the AR woofer, and while I had the cabinet open, glue in some braces. I thought about routing out the back, and adding a second AR, facing out. (Back to back) I don't know what would happen in terms of cabinet size, extension, etc. I am not trying to make a subwoofer here...more of a bass cabinet. It is net about 3 cf, and is currently sealed. I prefer sealed, but could add a vent if necessary. Larry at Madisound said that the guy who used to make those cabinets for him no longer does so. I wish he did, because I would just order a couple of new ones to play around with.

As far as amps and such, I have no constaints there. This would be active all the way. I have amps that can handle the different loads.

Does this make it any easier to quanitfy what is being attempted here? Thank you very much.

[homebuilder]

Sorry...typo on that AR woofer...Jack says it was designed for the Model 3 Limited, not the Model 9.

[homebuilder]

And, it has a poly cone, not paper.