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In Reply to: RE: BD-Design Orphean posted by Johno on July 24, 2023 at 19:05:08
I use BD Design Oris 150 horns driven by AER BD3 drivers with Fostex t900a bullet tweeters above Bill Fitzmaurice HT Tuba folded corner horn woofers. A little over a year ago the foam went bad on the AERs. I asked Bert what was the very best drivers for the Oris 150 horns. He recommended the addition of an adapter to convert the Oris 150s to accept 2" exit drivers and using the BMS 4592 ND coaxial compression driver. He stated that that was what he listened to in his system.
As you might know the AER BD3s are pricey and highly respected drivers. At that time I had the AERs rebuilt by AER, but I've not been able to get the BMS coaxial cmpression drivers out of my mind. I still might buy new 150 horns with the extensions and the BMS drivers in hopes that they will sound better than what I presently have.
I hope you get good response on this thread to help me decide.
I dream of an America where a chicken can cross the road without having it's motives questioned.
Follow Ups:
hi don!
i also have a pair of oris 150's. i was also considering a driver upgrade. can you tell me more about this recommended addition of an adapter to convert the Oris 150's to accept 2" exit drivers? i'm not sure how that would work - completely different shape - do the new drivers sit in the rear of the tube before the throat, or they get moved forward, or??? also, i was considering using the celestion axi2050's which i've read about.
my present system is an active quad-amped set-up, w/the oris' running 175hz-7khz, beryllium tweeters > 7khz, beefed up lascala bass bins w/pro audio drivers from 60hz-175hz, and four vmps larger subs <60hz (it's a big room; the 2nd pair of vmps are 19' behind the listening area against the wall.)
thanks!
doug s.
I have Oris 150 horns with AER BD-1 drivers, and their foam also needs replacing. The cost of AER doing the job (plus shipping to/back from Germany) is prohibitive for me. Did you explore other options? I have thought about trying cheaper drivers (Lii, Tang Band, etc.) but hard to imagine they would be anywhere near as good. I have Lowther DX-3 but found them much too peaky and annoying.
You mention both adapters for the coax drivers and new horns. Are the former a thing that Bert offers or would one need new horns to make the change?
I had a pair of Lowther DX4 drivers and their foam deteriorated. I looked around at replacement foam for the surround and spider and found Zenwoodaudio sells repair parts. I purchased the repair parts from him and after the repair, I thought that the drivers sounded even better than the original, although this is impossible to confirm without A/B testing. I don't know if the parts would work with AER drivers, but it would be worth looking into.
Zenwoodaudio has a youtube video showing how to make the repair, and it is very doable for a first time speaker repair.
A tragic story, but I was trying out different diffusers and a homemade rubber washer got twisted and blew out the former of one of my DX4 drivers - yikes!
So I purchased DX65 Lowther cones for replacements, and this has worked out really well for me. I use the DX65s in front waveguides.
I find the 15 ohm variety of Lowther drivers to have fewer issues in the treble. I ordered the 15 ohm, DX65 drivers with straight whizzer cones - based on a modification suggested by a long time Lowther user, in which I cut the end of the rolled edge of the DX4 whizzer cone and unfolded the whizzer - and found the high frequencies to be better.
Last comment, it is worth trying out different diffuser shapes with these wide range drivers - I have the Lowther bullet, holey doorknob and light bulb diffusers, but in my homemade waveguides, I found the Par light bulbs to work the best - the light bulb is the plastic variety with rounded edges and diffuser essentially covers the entire face of the cone, not the surround. If you want to see a different version of what I use, see the Beauhorn Virtuoso website for their diffuser.
Retsel
According to Bert he crosses the BMS compression drivers over at 180 Hz with them in the Oris 150 horn configuration I described above. I presently cross over to the HT Tubas at 200 Hz using a DEQX DSP to accomplish a 96 dB/octave crossover. Bert modifies the BMS drivers loosing 3 dB of sensitivity in the process. I'm guessing his modification allows a lower crossover point. I wouldn't play the HT Tubas as high as 200 Hz without the 96 dB crossover.
I didn't really consider alternatives to having AER rebuild the drivers. Mr. Keller at AER completely rebuilds the drivers reusing nothing but magnets and baskets. Including shipping to Germany from Georgia, USA and back the rebuild cost a hair under $4,000.00. The AER BD3s were originally great drivers, the rebuilt ones they are even greater.
I dream of an America where a chicken can cross the road without having it's motives questioned.
Unfortunately, $4,000 is not possible for me. The AER drivers look like they could use the same replacement surrounds that are offered for the Lowthers, but I am sure AER would say that is ridiculous. I read the comments somewhere online of a (presumably) professional re-coner in England who said repairing them was ridiculously difficult, and he would not do it again.
Yes, I recall that posting by John Pinnegar. I looked it up and I am reposting it below. It does seem that replacing the surround and spiders on AER drivers is very difficult, although not impossible. At that very high cost that AER charges, it seems that they likely just send new cones so you can mount your magnets to them.
Maybe AER should be honest up front that the future maintenance of their drivers is so pricey - Lowthers are more easily repairable, however they have a poor reputation due to the "Lowther Shout," which can largely be avoided, with a lot of shopping skill, and tweaking.
It was John who convinced me to cut the edge of the rolled edge of the whizzer cone and unfurl it - yes the higher frequencies were better and there was less out of phase cancellation between the whizzer and main cone.
Retsel
John Pinnegar old post:
"For many years I've repaired Lowther units, refoaming and sometimes repairing broken lead-in wires and voice coils.
I've had the unfortunate experience of refoaming a pair of AER BD2 units. Unlike a pair of MD units which I refoamed which had a wide magnet gap, the BD2 units have the Lowther style 1mm voice coil gap and which therefore requires very precise circularity of the voice coil.
This caused unexpected complications. When preparing a voice coil after refoaming for reinsertion into such a gap, it has to be precisely circular to within less than 1/4mm. The way of doing this is with a Lowther jig, a tapered mandrel upon which you force the voice coil down as far as it will go to stretch all give arising from non-circularity so as to ensure that it's as precisely circular as it can be. For good measure, I reverse the cone on the mandrel ensuring the whole voice coil tube is precise.
Using an aluminium mandrel the problem is that this can leave grey or black marks on the paper.
When the bloke saw this, even though it's hidden by a phase plug in normal use, he accused me of devaluing his units. There was a history to his dissatisfaction as the units had presented other problems, worse.
Another problem of refoaming units is that when the foam is really old and brittle, it snaps away from the paper crisply and gives little problem in cleaning. But when the foam is just on the point, it goes like a toffee goo and is a right beast to clean. And you have to clean it perfectly as you can't stick new foam on top of goo. So I use meths to dissolve it. The problem is that once dissolved, it can be carried by the meths on one's fingers and I accidentally left a dark finger-smudge on the cone from the meths in handling the cone whilst cleaning.
Oh dear. As far as I'm concerned speakers are to be heard, to sound, to sound perfect, and visual matters especially of old refurbished units are of secondary importance.
Of course the bloke could have sent them to AER to have them done at four or five times the cost . . . . but I really wonder if when you send a unit to AER for refoaming whether they really do send you back the original cone rather than simply inserting a freshly made one. The problems of removing goo, to say nothing of glue, and get perfect results make me wonder.
In handling a number of Lowther units and seeing how AER have copied them, clearly doing enough to avoid Lowther being hot under the collar, I really wonder what's necessary sonically and what's necessary simply not to be like Lowther, and when I see that claim that AER reproduce up to 80,000Hz when frequency graphs put it at around 20kHz top, I really wonder about everything.
Lowther units don't all have the "Lowther Shout". I think the reputation has been unfairly attributed. The C units which have Ferrite magnets can produce resonant frequencies in the region of the sound of cymbals - but this isn't necessarily because of the magnets. It's because there's a short paper cylinder connecting the voice coil to the cone, and resonances between one end of the paper and the other are not damped. This is cured by the A series and DX and EX with Alnico or Neodimium magnets. It's not the magnet that cures the shout but the longer length of paper cylinder connecting the two units and this provides enough disconnexion to interrupt any travelling waves. The paper is a treated paper like the rest of the cone. The foam spider used to be glued on with a brown glue, possibly shellac, which is brittle and often snaps away from the paper. I use Copydex, a latex glue for gluing the spider, which in future will always simply peel away from the paper.
It was coming to the gluing of the spider on the AER that I ran into real trouble. AER use some sort of glue possibly like silicone which can't be peeled off the paper without danger of tearing the paper. Unlike Lowther treated paper, the AER voice coil is on an untreated paper of the consistency of photocopy paper. Not only could I not remove the original glue, and can't imagine how AER can either, upon gluing on the new spider the water content of the Copydex glue simply disintegrated the paper. Inserting it onto the mandrel as a former to keep shape, it simply tore off. This was a surprise and a nightmare beyond contemplation.
Upon consulting an old friend who used to work for Lowther he said that they had this sort of problem from time to time and it was possible simply (not actually) to glue a new slither of paper inside to reconnect the voice coil to the cone and resolder the wires, and which even to my surprise I did successfully. So the unit was in working order again and working well, with no audible difference between the sound of the two newly refoamed units, the other one on which I'd used a thin silicone as glue.
As soon as I had the problem I confessed to the owner and this put him into the blackest of moods.
I'd loaned him a pair of the 97dB Lowther Challenge units available on ebay, which are rather good. (Perhaps I might talk about those on another thread) When he arrived to collect his AER units I asked him if he had brought my Chinese units back. He hadn't and from which I deduced that the bloke had come merely to haul me over the coals and give me grief.
He complained that I'd devalued his units, but the reality was that I handed back to him two perfectly serviceable newly refoamed working units.
AER charge 560eu each for refoaming (if in the light of what I've seen whether that's really possible) or 1500eu each for reconing and upgrading. So for anyone really wanting the latest most improved AER experience an upgrade should be the way to go and to ensure top value is kept in the units.
As he was extremely dissatisfied with the quality of my work, with a mark on one and the other with a repaired voice coil assembly, I didn't charge and I'll be surprised to see my Chinese units back again.
I wouldn't be surprised were he to have intended keeping and using my Chinese units, as they're good, and expecting to sell the refoamed AER units for top whack.
He told me that he'd seen on YouTube how simple it was to replace Lowther foams. Ha ha! I responded that if he'd done his AERs himself he'd have got into a worse mess than I had found myself in, and then not have been able to repair them at all.
Having looked at the AER and the Lowther units, for a number of reasons I know which I'd choose for myself. The roll back surround to the whizzer on the Lowthers needs to be flipped forward to restored to the original vintage format and then the A, DX and EX series are superb.
And for anyone wanting a cosmetic as well as a functional restoration of AER units, please do go to AER. I don't want to be in a situation of dissatisfaction ever again.
Best wishes
David P"
Thankyou,
typically, what life expectancy does the foam have on AER & Lowther drivers.
Cheers Johno
According to Mr. Keller at AER the foam he is currently using is good for twenty years or more. Since I will be seventy-five next month the foam will likely last the remainder of my life.
The old post by John Pimegar about the difficulty of a recone of AER drivers lends credence to Mr. Keller's claim that he reuses nothing except the magnets and baskets.
I dream of an America where a chicken can cross the road without having it's motives questioned.
I had my AER MD2 re-foamed (surround and spider) by ZenWood Audio. Great job. Highly recommended. Infinitely more affordable. Parts IRC were less than $50. Labor for both units (done in 2020) less than $300. Contact Sai KoHo of ZenWood Audio for current prices.
SMathews
That is great to know. My AER drivers need reforming, and I can't afford to send them back to Germany. Does Zenwood Audio have any other contact besides Facebook?
Thanks Don for the feedback the BMS compression drivers appear to have good longevity but that rebuild cost for the AER drivers is ridiculous.
Cheers Johno
But would your Tuba be good to 300Hz?
I have two Table Tuba 'Longs' doing Sub work for my Edgar Horns but doubt they would be ideal all the way up to 300Hz?
"Reality cannot exist because it cannot keep up with the lies on the Internet."
If you look at the attached URL under download they sho curves and what the response looks like at 110db with a passive crossover, and the driver roll off at around 700Hz. At 300Hz it appears to be 15db down, so some sort of EQ would be required to fill that hole.
Cheers
Remember the horn length is a major controller of how low the horn will load the driver. Figure it has to be 1/4 wl minimum and efficient operation begins about 1/2wl.
I have use this driver in products and also the B&C coax driver which is actually easier to make an ideal crossover between mid and high with than the BMS coax. Both can get down to 300Hz but takes a big exponential (curved wall) horn.
On the chart I downloaded it doesn't even show 300 Hz, has an impedance peak at 350 Hz and the graph stops at 400 Hz at about 8dB down from the 110dB marked on the chart?But...
They claim 300Hz to 7000 Hz for the mid compression driver.
They don't say what SIZE horn only 90 deg x 60 deg.?
Would Bert's HUGE horn make a difference?
"Reality cannot exist because it cannot keep up with the lies on the Internet."
Edits: 07/26/23 07/26/23
It has to the horn design - both a lower expansion of the throat, and size of the mouth, or else Cut-Throat would not get 115 db out of them, and a cutoff at 270 hz.
Retsel
As their specifications say 300Hz and the graph shows nothing after 400Hz and that down 15dB (if the y axis is 2dB per line?)
"Reality cannot exist because it cannot keep up with the lies on the Internet."
Attached image.
Cheers
I have no problem crossing this driver with my Orphean Horn to 270 Hz... Bert Of Oris says that you can go as low as 242 Hz., if you want to.
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