After visiting @Audio Elite in 2017 I knew I wanted to build speakers like that. Slowly but surely I gathered parts. 2nd hand or discounted. Since Stuart was not allowed to share the crossover schematic I had to find something else. But I saw something that was similar to the frequencies I "needed" to cover. I copied that and did a mod for the different tap on the Crites 3636 autoformer. I've posted the crossover pic but here is the complete system schematic.
I also decided on open baffle mid-bass. Because I could go active/dsp.
I also decided on open baffle mid-bass. Because I could go active/dsp.
My workshop is my back 'yard'
Jigsaw was hell in the 2.7cm oak. Luckily the horns mask that. Because I was in a hurry...the 4525 is not 100 straight...(Can still fix)
Jigsaw was hell in the 2.7cm oak. Luckily the horns mask that. Because I was in a hurry...the 4525 is not 100 straight...(Can still fix)
The crossovers pic is from before I asked chatgpt to calculate the value for first cap because the BMS is on a different tap than the design I copied. So with values seen the high pass was 1250 Hz. You can imagine my dissapointment.
Still have to make stands. Now leaning against my Bastanis OB.
I'm very happy. Some tracks like Manu Katché live drum solo... Had me.... Whaaaaaat!.. So dynamics are great. Voices. Piano and strings all good imo. Lots of Detail. All types of music sound good as well.
Listening at the moment. I cannot imagine anything better. Never heard better. Even with this 4535 horn that is I think the bottleneck. Very exciting to know there are better horns, caps and coils I can upgrade.
Just shows one what persistence and patience sometimes can lead to. I bought the BMS 2nd hand in August 2017. Probably abused all their life at concerts.
Some tlc and elbow grease.
Some tlc and elbow grease.
Also did the mod on the design flaw for the coax versions. For the hf part the bind posts need a recess. They cnc ed right through. Used a nylon washers sealed with pva glue. Put it in and add a new layer of wood glue.
Attachments
The 15” OB midbass was a great choice. When you build your stands/supports, consider some deeper ‘wings’ to increase the path length to cancellation with the front wave…..you’ll get a more tactile experience in the 100-120hz range where drums will really present like the real thing……it’s all about moving air.
My next OB midbass venture will be an 18” woofer heading up to 400hz where I can meet up with an 8” cone midrange driver.
My next OB midbass venture will be an 18” woofer heading up to 400hz where I can meet up with an 8” cone midrange driver.
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208. (RIP 2016 @ 102 Years Old).
I know Bert Doppenberg started to do this mod (for a premium) when he started to sell these drivers. I have and still use a early pair (bought at the distributor), with handwritten serial numbers. I never bothered to open the casing to do this mod as I appearently do not hear a problem myself, or the early ones did not have this design flaw yet, don't know. What would be the benefit to seal the openings, soundwise?
That's the problem if you don't compare before and after. I don't know if it truly was an issue. I just did it before I even implemented them. Just believed what I read on the Internet.
If it would be an issue, the professionals who use them full throttle in PA systems and studio's would certainly complain, I think. And BMS would correct the issue but they did not. It may sound better after the mod, because you know there is a mod (bias thing). But it can't harm to do it, so why not.
To remove the resulting and measureable cavity resonance.
It is there to function as a relief for the HF section leadout wires.
Why you also have to do a correction there to make it work.
What I found when doing the mod is that the binding posts connect to the voice coil via ferrous bolts. Typically 10 times more resistance than a brass bolt. They probably have a resistance of a couple tenths of ohms dwarfing the esr of capacitors. So I might replace those as well on the mid section. Already did it on the hf...(but not using the hf at the moment)
Out with the old in with the new. I was just too scared to do it on the mid driver...is it hard to put the voice coil in easily? The hf is childs play because the whole assembly comes off as a unit.
Out with the old in with the new. I was just too scared to do it on the mid driver...is it hard to put the voice coil in easily? The hf is childs play because the whole assembly comes off as a unit.
Last edited:
Just adding some tags/search terms
PAUDIO 4525, BMS 4592, HF10AK, 15PR400, JBL 4525, STH100, BMS 18N850
PAUDIO 4525, BMS 4592, HF10AK, 15PR400, JBL 4525, STH100, BMS 18N850