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JR-150 Speakers found in poor health - WWYD?


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It's not often a trip to the tip shop yields anything worth posting about, but, today, I found these:

 

PXL_20231106_223838244sml.jpg.23cd69def98ca9b7697714c6e9733eda.jpg

 

$20 later I got them up on the bench to figure out why they had been tossed, and the answer was pretty straight forward. While one unit of the pair seems to be functioning normally, the second had a crackling woofer. Pulling both woofers from the cabinet (tube?) I found one the one that more or less works has a slash in the rubber surround, a somewhat rough impedance curve according to my DATS (maybe normal resonances for these drivers?), and a job sticker on the back that suggests it had gone open at some point and was repaired. The second unit (Mr Crackles), had a DATS impedance sweep that was completely borked, and what looked to be a bit of a rough glue job on part of the surround. Also, the tweeters on both units, while functional, both have some grit on them that looks like it was attracted by some kind of oily residue on the tweeter dome itself. It's maybe nothing, but maybe not.

 

Here's where it gets really annoying - the woofers? They're not your standard 8 ohm KEF B110s or IMF equivalents - they're actually Audax HD13 B25H 16(!) ohm units. Extremely rare birds.

 

So, I see four paths forward:

 

1) send the drivers to someone for repair and hope they do a better job than the last, and that is doesn't cost more than fully functional JR150s are worth

2) replace all 4 drivers with Monacor SPH-135TCs, which are a dual 8ohm coil 5.25" that is pretty much the only thing similar that can be bought new (and wired in series for 16 ohm)

3) punt the whole thing on to someone else better equipped to deal with this sort of last-chance repair work, and wish them luck with their new project

4) return them whence they came

 

NB: I would check and likely replace the NP electrolytic caps on the crossover for options 1 and 2 as a matter of course, as I suspect that may be what fried the woofers in the first place.

 

I'm inclined to go for option 2, as I'm not a purist, and don't like to leave once-nice things broken. I appreciate this means that some of the notch filters and Audax driver specific elements of the crossover may lead to a few unwanted wrinkles in the frequency response, but I honestly wonder if that's any worse than trucking on with wonky old drivers with repairs on top of repairs, that may not actually behave as the crossover expects anyway. I've been down the path of driver repair before with other fixer-uppers, and while a Tannoy may warrant it, I honestly don't know if these do? It's great work that the specialist do, and worth more than what they typically ask, but, I don't even know if I'd like these once they're fixed.

 

What would you do?

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Having 149’s as a curiosity along with the matching separate bass driver, your description of what the enclosures contain indicates no original drivers as such so option 4 would be my choice. $20 is still $20.

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3 minutes ago, klm said:

Having 149’s as a curiosity along with the matching separate bass driver, your description of what the enclosures contain indicates no original drivers as such so option 4 would be my choice. $20 is still $20.

 

I had the same thought about sunk loses, although tbh I read all sorts of different accounts of which drivers were used depending on time of manufacture and model. Some KEF, some IMF, some Audax but 12 ohm rather than 16. I know that the woofers in the 150s are wired in parallel rather than 2.5, so it's possible higher than 8ohm is normal for them in order to keep the overall impedance above a certain level, which wouldn't have been a concern with the 149. I honestly don't know.

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10 hours ago, Cope said:

It's not often a trip to the tip shop yields anything worth posting about, but, today, I found these:

 

PXL_20231106_223838244sml.jpg.23cd69def98ca9b7697714c6e9733eda.jpg

 

$20 later I got them up on the bench to figure out why they had been tossed, and the answer was pretty straight forward. While one unit of the pair seems to be functioning normally, the second had a crackling woofer. Pulling both woofers from the cabinet (tube?) I found one the one that more or less works has a slash in the rubber surround, a somewhat rough impedance curve according to my DATS (maybe normal resonances for these drivers?), and a job sticker on the back that suggests it had gone open at some point and was repaired. The second unit (Mr Crackles), had a DATS impedance sweep that was completely borked, and what looked to be a bit of a rough glue job on part of the surround. Also, the tweeters on both units, while functional, both have some grit on them that looks like it was attracted by some kind of oily residue on the tweeter dome itself. It's maybe nothing, but maybe not.

 

Here's where it gets really annoying - the woofers? They're not your standard 8 ohm KEF B110s or IMF equivalents - they're actually Audax HD13 B25H 16(!) ohm units. Extremely rare birds.

 

So, I see four paths forward:

 

1) send the drivers to someone for repair and hope they do a better job than the last, and that is doesn't cost more than fully functional JR150s are worth

2) replace all 4 drivers with Monacor SPH-135TCs, which are a dual 8ohm coil 5.25" that is pretty much the only thing similar that can be bought new (and wired in series for 16 ohm)

3) punt the whole thing on to someone else better equipped to deal with this sort of last-chance repair work, and wish them luck with their new project

4) return them whence they came

 

NB: I would check and likely replace the NP electrolytic caps on the crossover for options 1 and 2 as a matter of course, as I suspect that may be what fried the woofers in the first place.

 

I'm inclined to go for option 2, as I'm not a purist, and don't like to leave once-nice things broken. I appreciate this means that some of the notch filters and Audax driver specific elements of the crossover may lead to a few unwanted wrinkles in the frequency response, but I honestly wonder if that's any worse than trucking on with wonky old drivers with repairs on top of repairs, that may not actually behave as the crossover expects anyway. I've been down the path of driver repair before with other fixer-uppers, and while a Tannoy may warrant it, I honestly don't know if these do? It's great work that the specialist do, and worth more than what they typically ask, but, I don't even know if I'd like these once they're fixed.

 

What would you do?

Monacors @ 16 ohm are a better driver than the Kef b110's IMO , having fitted a pair to JR149's - you have a bargain check dimensions first for fitting the Monacors  , but looks relatively straight forward 

keep at it 

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3 hours ago, stereo coffee said:

Monacors @ 16 ohm are a better driver than the Kef b110's IMO , having fitted a pair to JR149's - you have a bargain check dimensions first for fitting the Monacors  , but looks relatively straight forward 

keep at it 

Thank you - good to know someone has had experience with doing basically the same thing. Did the bolt holes line up for your 149s, or did you have to rotate 45 degrees and drill new ones?

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7 minutes ago, Cope said:

Thank you - good to know someone has had experience with doing basically the same thing. Did the bolt holes line up for your 149s, or did you have to rotate 45 degrees and drill new ones?

No bolt holes did not line up , and needed drilling new ones.  Might be different though for the Audax being replaced with Monacors  Mine are SPH 135TC

DSCF1262.JPG

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17 minutes ago, Cope said:

Do you happen to know the bolt hole distance centre to centre? Monacor don't seem to list it. The Audax are 134mm across, +/- 0.5 ish

Monacors are 138mm centre of hole to centre of hole   but hole width in the frame  is 8mm , so  likely will be close to fit depending on bolt dimension and head width of the bolt. With a steady hand and a drill press another 3mm is possible inward to move inward the width of the frame hole , which might be the best option

and its all flat as well. 

  

Edited by stereo coffee
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