Scanspeak? I always worry about the longevity of paper drivers. I've seen them literally disintegrate in vintage speakers
Sure. I trust you are familiar with HiFiCompass and their driver testing. Bliesmas come out as outstanding performers, like Purifi and some others. Measurements only don't tell the full story, hence I went for a listen. This is still not the full story as you still have to implement them, but it’s as far as I can go without spending the money.
Believe me, some significant soul searching going on before I cough out that much dough!
Oddly enough the Electro Voice 15W with a paper cone lived in South Louisiana for 40 years before moving to Denver Colorado. Original cone and surround about to play once it is beer time.
Where did you happen apon this chance? Someone nearby with a set already implemented?
I emailed Bliesma to ask some questions. Eventually asked if there would be DIYers that wouldn't mind me getting in touch. They noticed I was from Argentina and came back with a name that happened to be in my city - kind of odd! - and I went for a visit and heard what he assembled. A top-notch system. Serendipity happens!!
Wow. Very impressive. So, so expensive. Though perhaps worth it.
Interesting @LewinskiH01 , I went with the M74Ts, but the M142s (A or T not B! 🙂) again drifted into my thoughts this morning and I had a twinge of regret for not ponying up for them. I suppose it comes down to where we want the crossover. ~250Hz and 1.3-1.5K with the M142 and T34 v 500 and a bit higher with the M74.
My current research is trying to find a solution for 500hz and down.
Bill
I think one problem that quite often occurs with very old paper cone drivers is related to a moisture/climate situation
where the moisture actually leads to the corrosion of the 'flexible wires' that connect between the terminals and voice coil 🙁
One 'handy hint' I give to people using old woofers, is to gently coat these flexible wires with engine oil. [ not a thin WD40 spray ]
I heard the M74B and liked them very much. Didn't hear the A or T, but HiFiCompass provides comparisons in terms of measurements and his listening. Not sure if the difference from T to B is worth the extra money, but then again I didn't hear both.
The owner of the system I heard mentioned BluesMa was planning a M142B but issue in the B supply chain lead to canceling that plan. It would be a lot more expensive too - much more than the M142T! What I heard was the M142P. The owner is moving into M142T, which is the same one I'm thinking through.
I asked Bliesma and they aren't planning an intermediate sized dome between M74 and M142. So it's down to required xo and SPL needs. HiFiCompass shows 500Hz is lowest xo suitable for M74, and preferably 600Hz. M142 down to 250Hz.
My midbass is a SLOB with 8x 6.5" per side like xrk971' XSD but with different drivers. It goes naturally to 470Hz where it drops. I could push them to 550Hz, maybe 600Hz, but I need to test how they would sound. The M142 starting at 250Hz sounded very good but I don't really need to xo that low. But M74 needs a xo that might be too high for me.
FWIW, xrk971 SLOB work amazingly well. You could look into a similar setup with smaller drivers and achieve 550Hz xo. I just happen to have built with 6.5" already. Even with 6.5" it does get easily to 470Hz and probably to 500Hz too.
You are dead on right: I checked their prices and the M74B is more expensive than the M142T, at €1200 vs. 1100 approx! Beryllium has gotten very expensive!!
That's probably one of the reasons I cross over lower with my active crossovers without problems. You have the full dampening of the amp at the resonance frequency. The passive crossover goes high impedance exactly where the driver resonates the most.
Just for all - you can cross an M74 for sure lower as 500Hz! Here is the THD curve of an M74A at 100dBSpl and different crossovers:
At 600Hz I had a dip in the FR (baffle), so this THD peak is more pronounced as the driver produces it. It was the test setup to compare midranges, not a finished speaker.
I did a passive crossover 2nd order with 470Hz crossover frequency - and this speaker get's tortured (measurement speaker, loud sine sweeps all day). No problem.
At 600Hz I had a dip in the FR (baffle), so this THD peak is more pronounced as the driver produces it. It was the test setup to compare midranges, not a finished speaker.
I did a passive crossover 2nd order with 470Hz crossover frequency - and this speaker get's tortured (measurement speaker, loud sine sweeps all day). No problem.
I did measurements from a lot of PA 8" and most of them have high THD at low levels - 8NMB420 is especially bad. I have posted the measurements a few times but can look after them later the day. So do your testing with the B&C when using them!
Satori MW19 should be an easy ride - I would even go one bigger with WO24. These drivers are not a point in space - there is a radiating area and these rules are not hard borders, there is a wide transition. I would still use at least 2 of them but preferable as a 3.5 way (+ sub).
The measurements:
18Sound 8NMB420, THD over frequency at different levels:
PHL 2460:
Which one would you use for HiFi?
18Sound 8NMB420, THD over frequency at different levels:
PHL 2460:
Which one would you use for HiFi?
I agree with active xover, as the amp is more in control over dampening. The problem is still there depending on how hard and long the mid is run that way. It will eventually wear the suspension harder than with a higher xover. How much wear can it deal with over time? No one knows yet (at least no one is mentioning anything).
The suspension on these M74 is textile with some sort of treatment, so not much different than other mid domes. The Visaton DSM50FFL has a supronyl suspension. It may be more tolerant, but its a 2' dome, so can't be crossed as low.
Between the other 2" domes I have, Morel MDM55, Visaton DSM50FFL, Dynaudio D52AF and 3", SS D7608, Bliesma M74A, the only ones with non textile suspension are the DSM50FFL. These have a wide suspension that is very compliant. I have used them at 700 hz 2nd order but they don't go as loud. For more SPL, I'd run these above 900 hz 2nd order, but they will do 800 hz much cleaner with an LCR @ Fs. 105 dB isn't an issue under those circumstances.
The prohibitive thing crossing low with LCRs is the cost it adds with passive xovers. At those lower frequencies, the parts are bigger and more expensive. You can integrate Rmin into the coil with thinner wire, which can substantially lower the cost. You are looking at 4mH or more at those frequencies, so Rdc needs to be around 6 ohms for a single 8 ohm mid and about 4 ohms for 6 ohm mid. This may vary a little and will be up to some fudging afterwards. With 20 guage wire you can get close with a single M74A.
If you've never heard the difference (THD measurements aside) with or without a physical LCR at lower xover on these domes, you're in for an eye opener. The output capability at lower crossover is substantially cleaner and more linear. With higher capacity, multi driver setups using 2 or 3 x MDM55s with an LCR, it surpasses a single 3" mid, even with a 600 hz 2nd order HP. This is with shading one or two drivers going the full distance of 600 hz - F max and only 1 or 2 domes playing the partial range of 600 to 900 hz, rolling off 1st order past that point. With slimmer baffles, the low end assistance will need to increase out of obvious reasons.
The M74A is substantially more capable going lower, but still needs an LCR if you're using a single one past 500 hz at higher output past 105 dB. I have tried a 10" and 12" with a single M74A @ 500 hz LR2. It definitely needs an LCR, otherwise you risk smacking the dome into the front grille without the notch @ Fs. The baffle width greatly affects this, so if you want wide dispersion down low, you'll for sure need to deal with a passive LCR. The low xover is substantial enough to force the M74A into over excursion past 3mm peak when playing it really loud with a capable woofer. It can keep up with at least a single 12" crossed around 500 hz 2nd order. Both the Eminence KL3012LF and SB34NRXL can do the job. Im still torn between 2 x KL3012LF, SB34NRXL or CB3010N-8 with 2 of my M74A per side.
The SB34NRXL can definitely do 500 hz 2nd order with the M74A. It will push the M74A hard post those points. My 2nd option is multiple smaller midbass in the coincidental arrangement I posted in another thread, but some have cited an issue with acoustic center and phase / timing at crossover of 500 hz.
The suspension on these M74 is textile with some sort of treatment, so not much different than other mid domes. The Visaton DSM50FFL has a supronyl suspension. It may be more tolerant, but its a 2' dome, so can't be crossed as low.
Between the other 2" domes I have, Morel MDM55, Visaton DSM50FFL, Dynaudio D52AF and 3", SS D7608, Bliesma M74A, the only ones with non textile suspension are the DSM50FFL. These have a wide suspension that is very compliant. I have used them at 700 hz 2nd order but they don't go as loud. For more SPL, I'd run these above 900 hz 2nd order, but they will do 800 hz much cleaner with an LCR @ Fs. 105 dB isn't an issue under those circumstances.
The prohibitive thing crossing low with LCRs is the cost it adds with passive xovers. At those lower frequencies, the parts are bigger and more expensive. You can integrate Rmin into the coil with thinner wire, which can substantially lower the cost. You are looking at 4mH or more at those frequencies, so Rdc needs to be around 6 ohms for a single 8 ohm mid and about 4 ohms for 6 ohm mid. This may vary a little and will be up to some fudging afterwards. With 20 guage wire you can get close with a single M74A.
If you've never heard the difference (THD measurements aside) with or without a physical LCR at lower xover on these domes, you're in for an eye opener. The output capability at lower crossover is substantially cleaner and more linear. With higher capacity, multi driver setups using 2 or 3 x MDM55s with an LCR, it surpasses a single 3" mid, even with a 600 hz 2nd order HP. This is with shading one or two drivers going the full distance of 600 hz - F max and only 1 or 2 domes playing the partial range of 600 to 900 hz, rolling off 1st order past that point. With slimmer baffles, the low end assistance will need to increase out of obvious reasons.
The M74A is substantially more capable going lower, but still needs an LCR if you're using a single one past 500 hz at higher output past 105 dB. I have tried a 10" and 12" with a single M74A @ 500 hz LR2. It definitely needs an LCR, otherwise you risk smacking the dome into the front grille without the notch @ Fs. The baffle width greatly affects this, so if you want wide dispersion down low, you'll for sure need to deal with a passive LCR. The low xover is substantial enough to force the M74A into over excursion past 3mm peak when playing it really loud with a capable woofer. It can keep up with at least a single 12" crossed around 500 hz 2nd order. Both the Eminence KL3012LF and SB34NRXL can do the job. Im still torn between 2 x KL3012LF, SB34NRXL or CB3010N-8 with 2 of my M74A per side.
The SB34NRXL can definitely do 500 hz 2nd order with the M74A. It will push the M74A hard post those points. My 2nd option is multiple smaller midbass in the coincidental arrangement I posted in another thread, but some have cited an issue with acoustic center and phase / timing at crossover of 500 hz.
For example, the B&C 8NDL51 is a fabulous midbass. It has very low distortion but the motor noise is something to watch out for. If you put this driver in a small sealed box, it will beat almost anything in terms of HD and other categories. You wouldn't be able to use this driver in a dipole due to the motor.
Trying various tweeters with dome mids, I'd say there isn't a tweeter out of the picture below that wouldn't blend well with any of the dome mids I'm aware of.
The easiest to deal with dome mids are the smaller Morel MDM55 (CAM558) and Visaton DSM50FFL.You can cross them almost anywhere up to 5k and even higher.
If some of the Hivi and Dayton dome mids were consistent enough, they'd be on the list as well. For their cost, they don't compare.
If you compare the cone mids which are in a similar league, thosee are just a handful which could compete at a similar price to performance ratio. Among those are the Peerless 830870, NE123W, NE149W, P13WH-00-08, Vifa 10MD39. The ScanSpeak 10F8424G is a great one, but it pushes the price performance ratio boundary like many other higher end cone mids.
I'm going to be measuring the above tweeters with the following dome mids - Bliesma M74A, Morel MDM55(CAM558), SS D7608, Visaton DSM50FFL, Dynaudio D52AF and SB MD60N.
The easiest to deal with dome mids are the smaller Morel MDM55 (CAM558) and Visaton DSM50FFL.You can cross them almost anywhere up to 5k and even higher.
If some of the Hivi and Dayton dome mids were consistent enough, they'd be on the list as well. For their cost, they don't compare.
If you compare the cone mids which are in a similar league, thosee are just a handful which could compete at a similar price to performance ratio. Among those are the Peerless 830870, NE123W, NE149W, P13WH-00-08, Vifa 10MD39. The ScanSpeak 10F8424G is a great one, but it pushes the price performance ratio boundary like many other higher end cone mids.
I'm going to be measuring the above tweeters with the following dome mids - Bliesma M74A, Morel MDM55(CAM558), SS D7608, Visaton DSM50FFL, Dynaudio D52AF and SB MD60N.
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The 8NMB420 is better behave all around than the PHL. They both however have their own issues which will need attention that passive filters won't be able to tackle sufficiently. I'd rather use the B&C 8NDL51 or SB 6MW150D.
Better yet, the WO24TX would be better if funds allow it. The SB34NRXL is IMO the best price to performance ratio but realistically restricted to 400 hz. The Eminence KL3012LF and CB3010N-8 are better candidates due to higher sensitivity. The Beta-8A could be a lower end, bandwidth limited option.
Thank you, @profiguy and @IamJF for your continued words of wisdom.
I have been looking at the WO24TX and read the review on @HiFiCompass . Looks great for up to 500Hz other than the little resonance found at 400Hz. I wonder about its significance, if any.
https://hificompass.com/en/reviews/satori-wo24tx-8-95-textreme-cone-woofer
Though it wouldn't go as deep as the Purifi PTT10 or WO24, this driver looks interesting. The sensitivity v the others is appealing. Would love to see HiFiCompass-level measurements:
https://www.kartesian-acoustic.com/product/wom265_vki-6
Though perhaps I should just reconcile myself to the low sensitivity of the PTT10 and get a more powerful amp, it otherwise seems perfect for the job.
Bill
I have been looking at the WO24TX and read the review on @HiFiCompass . Looks great for up to 500Hz other than the little resonance found at 400Hz. I wonder about its significance, if any.
https://hificompass.com/en/reviews/satori-wo24tx-8-95-textreme-cone-woofer
Though it wouldn't go as deep as the Purifi PTT10 or WO24, this driver looks interesting. The sensitivity v the others is appealing. Would love to see HiFiCompass-level measurements:
https://www.kartesian-acoustic.com/product/wom265_vki-6
Though perhaps I should just reconcile myself to the low sensitivity of the PTT10 and get a more powerful amp, it otherwise seems perfect for the job.
Bill