I wouldn't normally consider using a different driver for a specific enclosure design but as the Alpair 6 and Jordan JXR6HD specs are so close ...
Does Jim or anyone consider the two driver close enough to use the JXR6 in this MLTL design and if so which parameters (if any) will need adjusting?
Specs on the JXR6 pair I have are:
FO Hz - 65 Hz
Qm - 1.634
Qe - 0.71
Qt - 0.495
Re ohms - 4.498
Vas - 3.051 litres
Xmax p-p - 6.00 mm
SPL 1m 1w - 85.38
These are the standard specs for the last batch made by Mark - the F0 was measured for this pair by Ted. I initially thought the JXR6 would be unsuitable a it lacks a rear spider but I think the Alpair is the same. Is this correct?
Does Jim or anyone consider the two driver close enough to use the JXR6 in this MLTL design and if so which parameters (if any) will need adjusting?
Specs on the JXR6 pair I have are:
FO Hz - 65 Hz
Qm - 1.634
Qe - 0.71
Qt - 0.495
Re ohms - 4.498
Vas - 3.051 litres
Xmax p-p - 6.00 mm
SPL 1m 1w - 85.38
These are the standard specs for the last batch made by Mark - the F0 was measured for this pair by Ted. I initially thought the JXR6 would be unsuitable a it lacks a rear spider but I think the Alpair is the same. Is this correct?
Use of Generation 2 Alpair 6 Drivers
I recently did a little study to determine the functionality of Alpair 6.2 drivers in my Alpair 6.1 MLTL design. My original design used the first generation metal cone Alpair 6 drivers but only second generation drivers are currently available. The second generation drivers are the Alpair 6.2P (paper cone) and 6.2MA (metal cone).
In my simulations I use Martin King’s excellent worksheets to derive performance plots of the driver within the enclosure. In the Martin King simulations you enter the T/S specifications for the specific driver you plan to use. Next you enter an enclosure model which consists of the box length and cross-sectional area, driver location, port location, port length and diameter, and stuffing density. You then vary the box parameters and iterate until you achieve acceptable results. I usually aim to have flat frequency response down to the 3 dB corner frequency. Then I check the other performance curves to verify adequate results for impedance, phase, deflection, etc.
I re-ran my simulation model with the 6.1 driver and then plugged in Thiel/Smalle parameters for the 6.2P and 6.2MA drivers. I retained the same enclosure model for all three cases so only the T/S specs were changed for each driver. All T/S specs used were the values given on the Mark Audio and Madisound websites. For the MLTL enclosure entries I used the dimensions that I gave in the first message in this thread. Now if you compare the T/S specs for the 6.1, 6.2P, and 6.2MA drivers, there are minor differences between the three drivers. The question I had was whether the different drivers would yield similar performance results.
My MLTL Alpair 6.1 design yielded a 3 dB down point (F3) at 44 Hz with a port length of 4”. When I compared the performance curves of the three drivers, the SPL response vs. frequency plots were nearly complete overlays. The 6.1 and 6.2P drivers differ only by width of the ink lines on thier plots while the 6.2MA driver seems to have a shift of less than 0.5 dB higher SPL level vs. the other two drivers.
Thus I concluded that any of these three drivers will perform the same in my MLTL box. Of course T/S specs may differ across the production of these drivers so it is always best to measure your own drivers and rerun the simulation model to ascertain the expected results. Fortunately, most of the Mark Audio drivers are built in a single manufacturing lot so differences should be very small.
I recently did a little study to determine the functionality of Alpair 6.2 drivers in my Alpair 6.1 MLTL design. My original design used the first generation metal cone Alpair 6 drivers but only second generation drivers are currently available. The second generation drivers are the Alpair 6.2P (paper cone) and 6.2MA (metal cone).
In my simulations I use Martin King’s excellent worksheets to derive performance plots of the driver within the enclosure. In the Martin King simulations you enter the T/S specifications for the specific driver you plan to use. Next you enter an enclosure model which consists of the box length and cross-sectional area, driver location, port location, port length and diameter, and stuffing density. You then vary the box parameters and iterate until you achieve acceptable results. I usually aim to have flat frequency response down to the 3 dB corner frequency. Then I check the other performance curves to verify adequate results for impedance, phase, deflection, etc.
I re-ran my simulation model with the 6.1 driver and then plugged in Thiel/Smalle parameters for the 6.2P and 6.2MA drivers. I retained the same enclosure model for all three cases so only the T/S specs were changed for each driver. All T/S specs used were the values given on the Mark Audio and Madisound websites. For the MLTL enclosure entries I used the dimensions that I gave in the first message in this thread. Now if you compare the T/S specs for the 6.1, 6.2P, and 6.2MA drivers, there are minor differences between the three drivers. The question I had was whether the different drivers would yield similar performance results.
My MLTL Alpair 6.1 design yielded a 3 dB down point (F3) at 44 Hz with a port length of 4”. When I compared the performance curves of the three drivers, the SPL response vs. frequency plots were nearly complete overlays. The 6.1 and 6.2P drivers differ only by width of the ink lines on thier plots while the 6.2MA driver seems to have a shift of less than 0.5 dB higher SPL level vs. the other two drivers.
Thus I concluded that any of these three drivers will perform the same in my MLTL box. Of course T/S specs may differ across the production of these drivers so it is always best to measure your own drivers and rerun the simulation model to ascertain the expected results. Fortunately, most of the Mark Audio drivers are built in a single manufacturing lot so differences should be very small.
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So, I have had a pair of original Alpair 6's hanging around since they first came out. I have tried them in three different boxes with results from nothing special to okay. About 3 weeks ago I was cleaning up and saw them in the last cabinet I tried, I think they were Needles.
I got the bug to make something so decided on Jim Griffin's MLTL. I had the wood and it would be a quick build. That was about 3 weeks ago.
I think Mr. Griffin is being quite modest, these speakers sing in this enclosure. This is my first MLTL so am late to the party but now that I am here plan to stay for awhile.
The reproduction is very good from top to bottom, even and balanced sound. They don't draw any particular attention to any specific frequency range, they just sound "right".
I have them in large room, 16 X 40 just putting time on them, about 2 feet from the rear wall and 3 feet from the side walls but I dare say in a smaller room these things are going to truly shine.
Although I seem to going for smaller speakers of late, based on the strength of this speaker from Mr. Griffin I may just try the Alpair 10 design he has shared with us.
Thanks for sharing Mr. Griffin.
Andrew
I got the bug to make something so decided on Jim Griffin's MLTL. I had the wood and it would be a quick build. That was about 3 weeks ago.
I think Mr. Griffin is being quite modest, these speakers sing in this enclosure. This is my first MLTL so am late to the party but now that I am here plan to stay for awhile.
The reproduction is very good from top to bottom, even and balanced sound. They don't draw any particular attention to any specific frequency range, they just sound "right".
I have them in large room, 16 X 40 just putting time on them, about 2 feet from the rear wall and 3 feet from the side walls but I dare say in a smaller room these things are going to truly shine.
Although I seem to going for smaller speakers of late, based on the strength of this speaker from Mr. Griffin I may just try the Alpair 10 design he has shared with us.
Thanks for sharing Mr. Griffin.
Andrew
Like all the 2nd+ generation drivers (when Mark really started adding his own touch to the drivers) the A6.2 are quite a bit better than the 1st gen A6 which are quite close to the Jordans which Mark was doing for Ted for the previous 5 years.
I could not live with the A6.1, i really like the A6.2x
dave
Hi Dave,
Please elaborate. Better with regards to ?
I am really smitten by the 6.1 in these MLTL's.
I have always been a fan of the FE103 but not sure if its because my taste is changing but the Alpairs I have sound better in just about everyway.
The FE103 shines in the midrange, a bit coloured but I like it.
The Alpair 6 shines throughout but I would not call them coloured.
Would the A7 be a similar upgrade over 6.2 in your opinion?
With the UK pound in a slump I might spring for a pair of Jordan Eikona and put them down for later. Always wanted a pair of Jordans.
Andrew
Please elaborate. Better with regards to ?
I am really smitten by the 6.1 in these MLTL's.
I have always been a fan of the FE103 but not sure if its because my taste is changing but the Alpairs I have sound better in just about everyway.
The FE103 shines in the midrange, a bit coloured but I like it.
The Alpair 6 shines throughout but I would not call them coloured.
Would the A7 be a similar upgrade over 6.2 in your opinion?
With the UK pound in a slump I might spring for a pair of Jordan Eikona and put them down for later. Always wanted a pair of Jordans.
Andrew
Except for possibly bass extension, they do almost everything better. In particular they do not have the annoying problems in the top (which doesn't seem to bother some, it is not as bad as in the JX92) and better ability to allow the passing of low level information (DDR).
Me too, but the latest FE103En are not really my cup of tea. The FE103 SOL is considerably better, a shame they have all gone.
A7.3 is the best driver that MA produces in my opinion. In my experience it is a toss-up between A7.3eN and the ultra rare A7 MOAP.
I'd love to try a pair too but they are so expensive and they would have to be considerably improved over the JX92 (which people say they are) to outperform the Mark Audios. I've had 3 sets of JX92 those i could not live with. The Eikona is comparable size wise to the MA A10.x, the latest ones coming much closer to the A7.3 in what they do, and with the extra bass extention probably making them a better driver for most (where their systems would not pass the low level information that sets the A7.3 ahead).
Worth noting that before Ted sold Jordan to the Swedes (and then took it back because he wasn't happy with what they were doing), Mark Fenlon was doing all the Jordans.
dave
Port question
I found a pair of the first generation drivers and have decided to build this design. The wood is already cut and I am now thinking about binding cups and ports.
Could someone provide with a link to an appropriate port for this MLTL in Europe? Jim, did you use a straight or a flared port? I found this port at parts express.
Also, I am interested in sourcing a binding post similar to this one or this one in Europe. Any help would be appreciated! I used to use Speakon but it is not very practical for adding a baffle step correction circuit...
I found a pair of the first generation drivers and have decided to build this design. The wood is already cut and I am now thinking about binding cups and ports.
Could someone provide with a link to an appropriate port for this MLTL in Europe? Jim, did you use a straight or a flared port? I found this port at parts express.
Also, I am interested in sourcing a binding post similar to this one or this one in Europe. Any help would be appreciated! I used to use Speakon but it is not very practical for adding a baffle step correction circuit...
Yje 2nd set of binding posts with th eplastic nuts are better sounding. The easiest way to deal w ith the vent is to use a piece of plumbing pipe. Correct size adjustment can be calculated using this: http://p10hifi.net/FAL/downloads/ChangingPortSize.pdf
Or what i would do is convert to a slot vent.
dave
Or what i would do is convert to a slot vent.
dave
Yeah, I like that one also but the shipping and customs charges (mandatory with PE for some reason even on orders that don't require them) are way too high. Haven't seen anything comparable on this side of the pond.
As for the slot vent, I was worried it would not be accurate enough with these small dimensions (1,11cm x 10,2 cm). It seems that even a few mm would change the area quite a lot.
I have found some 40mm pvc pipe in the local hardware store but without the flange a nice finish on the front may be beyond my skills. On my tabaq build I hid such a port on the back but wish I hadn't because now I can't shove them up against the back wall.
FWIW, I've been building a series of boxes designed by Dave and Scott for years (decades? 
) that primarily use slot ports - some with quite a high aspect ratio - i.e. very short / wide or tall/narrow, depending on the orientation. They offer a lot of construction advantages, particularly when located at the end of enclosure - not the least of which is the ability to fine tune by the use of filler strips.
Just take a look at many of the mini-onken family, for both Fostex and Mark Audio drivers - in some cases the distinguishing factor between models is the net amount of CSA of the often divided slot ports.
) that primarily use slot ports - some with quite a high aspect ratio - i.e. very short / wide or tall/narrow, depending on the orientation. They offer a lot of construction advantages, particularly when located at the end of enclosure - not the least of which is the ability to fine tune by the use of filler strips. Just take a look at many of the mini-onken family, for both Fostex and Mark Audio drivers - in some cases the distinguishing factor between models is the net amount of CSA of the often divided slot ports.
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