The PM6 drivers in my Lowther Acousta cabinets are faulty and attempts at local repairs (South Africa) were unsuccessful.😡
Any suggestions for a drop-in replacement; TangBan 1772 perhaps ?
Any suggestions for a drop-in replacement; TangBan 1772 perhaps ?
These might interest you.
PAIR of 8" fullrange drivers + copper pole piece for Lowther horn speakers or OB | eBay
I had the cheaper ones he used to sell and they were actually very good. Have not tried these.
PAIR of 8" fullrange drivers + copper pole piece for Lowther horn speakers or OB | eBay
I had the cheaper ones he used to sell and they were actually very good. Have not tried these.
TB1772 is a great performer, but I doubt requires as elaborate a BLH enclosure as the Acoutsa, and even without the asymmetrical flange pattern if rebated, I think there are few truly drop-in replacements for a PM6.
You could try exchanging your drive units. If you click on "drive units" and exchange upgrade scheme, take a view. The fall in the GB Pound might help a bit.
Lowther Loudspeakers
Lowther Loudspeakers
Thank you but I'm looking for alternatives cheaper and more reliable (ie. bigger magnetic gap and not foam surrounds.....).
I think you need to look further than just whether the driver will physically fit and has comparable sensitivity, Fs etc. From the few occasions in which I've heard Lowthers, replicating their characteristic tonality will be the tricky part.
I usually trust 3rd party measurements more than manufacturer's measurements.
The best 3rd party measurements I've seen for Lowther are here, but only for the DX units:
Preliminary Measurements of the Lowther DX Series of Drivers
The PM6 is advertised as 1.75 Tesla. The DX2 is probably the most similar of the DX units (1.7 Tesla).
Note that all three DX drivers measured have relatively high Fs and small Vas.
...so I'd recommend hunting through other 3rd party info for the 8" drivers which have similarly high Fs and small VAS, as being the most likely to work with an existing cabinet.
This is a good place to start:
Loudspeaker Raw Driver Measurements
Based on this guesswork & Rutcho's info, the ebay (GUI Sound?) driver is a better match than the TangBand 1772.
DX2 ---GUI ---TB1772
55.6 - 57.3 - 42.0 Fs
45.1 - 32.0 - 87.0 VAS
95.6 - 96.0 - 95.0 SPL
The best 3rd party measurements I've seen for Lowther are here, but only for the DX units:
Preliminary Measurements of the Lowther DX Series of Drivers
The PM6 is advertised as 1.75 Tesla. The DX2 is probably the most similar of the DX units (1.7 Tesla).
Note that all three DX drivers measured have relatively high Fs and small Vas.
...so I'd recommend hunting through other 3rd party info for the 8" drivers which have similarly high Fs and small VAS, as being the most likely to work with an existing cabinet.
This is a good place to start:
Loudspeaker Raw Driver Measurements
Based on this guesswork & Rutcho's info, the ebay (GUI Sound?) driver is a better match than the TangBand 1772.
DX2 ---GUI ---TB1772
55.6 - 57.3 - 42.0 Fs
45.1 - 32.0 - 87.0 VAS
95.6 - 96.0 - 95.0 SPL
Many thanks for the links.
The Lowther Acousta cabinet has a magnet cavity cut-out of 103 mm diameter which means the GUI unit will not fit at 145 mm whereas the TB 1772 is 95 mm.
The Lowther Acousta cabinet has a magnet cavity cut-out of 103 mm diameter which means the GUI unit will not fit at 145 mm whereas the TB 1772 is 95 mm.
You are unlikely to find a drop-in replacement. You're basically asking for a unit that isn't a Lowther but possesses the same Fs, Qt and Vas (necessary for it to be a drop-in replacement, acoustically), which also possesses the same basket and magnet dimensions, topped off with a lower price & more robust construction. That's not going to happen. I can't think of anything, off-hand, that will suit, and I'm fairly familiar with the wideband driver market. If you're willing to do a bit of DIY work, you might make a Fostex FE206En go in, but if you're wanting a straight swap, the only thing that's likely to do is another Lowther of the same variety.
One further point for consideration: the Acousta cabinet is not exactly the most distinguished example of a back-horn under the sun. So, to be brutally honest, unless you have an emotional attachment to the cabinets for xyz reason (fair enough if that's the case) then you may well be better off taking this as a sign that the time has come for a change, sell off the Acoustas (with or without the shot drivers) and building, or having someone build for you, a new pair of speakers for your preferred drive units. There are a lot of good projects out there, and a lot of good drivers. It may be a bit of a financial hit initially, but long-term is probably going to work out as the more practical option.
One further point for consideration: the Acousta cabinet is not exactly the most distinguished example of a back-horn under the sun. So, to be brutally honest, unless you have an emotional attachment to the cabinets for xyz reason (fair enough if that's the case) then you may well be better off taking this as a sign that the time has come for a change, sell off the Acoustas (with or without the shot drivers) and building, or having someone build for you, a new pair of speakers for your preferred drive units. There are a lot of good projects out there, and a lot of good drivers. It may be a bit of a financial hit initially, but long-term is probably going to work out as the more practical option.
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I was thinking this, but didn't have enough confidence in my knowledge to deliver that bad news 🙁
I was also wondering about this.
The only Acoustas I've heard looked cheaply made and were in pretty ratty condition. They had hand-made Lowther clones in them - but they sounded surprisingly good, on a brief (loud!) demo.
If the OP's Acoustas are also in poor shape, and if (s)he isn't wedded to what he had, another possibility could be to do a hackjob on them.
1) Drill out the interior panels; convert the Acoustas to a standard ported enclosure.
2) Mount an adaptor plate to use a 6.5" of appropriate specs, in the 8" hole
3) Hack the interior panel to allow mounting of a deeper driver.
...or some combo of these.
I'd be tempted to use an Eminence BETA-8CX. It ticks all the boxes, being an 8", mass-produced, robust and cheap, with specs that look like a good match. I think lower efficiency is the penalty for all that.
Eminence Beta 8CX coaxial speaker. The Eminence Beta 8CX is a 8" 8 ohm coaxial speaker.
DX2 ---8CX
55.6 - 54.0 Fs
45.1 - 34.9 VAS
0.30 - 0.31 Qts
95.6 - 92.0 SPL
The depth is 89mm. There are two 'problems':
- to also fit the compression driver, you'd have to cut a hole, and mount a little cup or recess into the panel behind the driver.
- being a coaxial rather than an 8" using a whizzer, you might accidentally get fairly smooth response, nothing like the original.
Attachments
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Pardon me but I'm totally mystified how you can expect to choose a replacement driver without trying it out to see if you like it's 'sound characteristics' particularly in comparison to the faulty Lowthers?
Surely the bottom line is all about the sound, yes?
Surely the bottom line is all about the sound, yes?
I'd like to experiment with an extended whizzer - is there a non-destructive way to attach the extension, get good enough coupling, yet have it removable without damaging the main whizzer's paper? What's a good paper to use for the extension?
FWIW I had 1772 in the little BK20 and subjectively was decent- don't think it was peaking on the bottom but didn't bother to measure things.
FWIW I had 1772 in the little BK20 and subjectively was decent- don't think it was peaking on the bottom but didn't bother to measure things.
I just looked up the story of the Acoustas and now understand. These things have a very long history. One of the comments though was how the later models were cheaply constructed out of MDF and that you should stick to the plywood models. Maybe the MDF was what you saw/heard.
Given their history it may or may not be worth trying to replace the drivers with something modern, but the whole point of them was the original drivers.
Unfortunately true.
Leaving cabinet material aside, the Acousta horn design isn't going to win many awards; top that off with questionable build? Ejecting niceties, I'd get shot of them, along with the clapped-out drivers, and move on. Life's too short, especially since there are a large number of quality alternatives out there that would likely provide a performance upgrade also.
Leaving cabinet material aside, the Acousta horn design isn't going to win many awards; top that off with questionable build? Ejecting niceties, I'd get shot of them, along with the clapped-out drivers, and move on. Life's too short, especially since there are a large number of quality alternatives out there that would likely provide a performance upgrade also.
Ding.
Good question also for attaching accelerometers, etc. Any answers like glue that releases when put in freezer? Or self-destructs in 3 days? Or adheres only above (or below) 75F? Or that resists decomposing as long as tweeted news?
B.
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As far as attaching accelerometers to a wideband driver's cone is concerned, I would say that's the least of the problems. Since all wideband MC drivers generate the majority of their BW through resonance, and both the accelerometer and the adhesive have mass, as far as I can see by physically attaching it you have immediately added mass-damping to that part of the substrate, altering its resonant profile away from what was intended, and invalidating the results since it is no longer operating as designed.
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