JBL D-130s & Altec 511b horns...
- Thread starter Redboy
- Start date
These are 8-Ohm to match with your crossover.Redboy said:
Mounting is metric bolts, so you'll have to make a run to the hardware store. They're not the M6 specified in the data sheet, tho, I don't believe. Tell everyone here what they are once you make the determination, please.
Also, while there, get the right size Fastons. Do NOT solder to the driver terminals, as they are only supported mechanically by the plastic of the diaphragm back cap. Heat that up very much, and they'll pull out. :nono:
Just hook 'em up to your crossover, and you'll get the first FR curve, above. That's quite listenable, actually. Just a little more I want to try on the compensation, and I'll post the details here.... :thmbsp:
Do some comparative listening with the Altec drivers and let us know your findings. Also, do you have to pad the BMS down significantly more (as the specs would suggest) to achieve acoustic "balance" with your woofers?
Try both "phase" options on the driver connection. Pick whichever sounds best to you. I'm running in-phase here, but that may not be optimum for your setup.
The threads on the BMS4550 are indeed relatively common 6mm dia. Specifically, they're designated as M6-1.00 X (length). I verified this with my handy-dandy Mitutoyo thread gage. Considering the typical Altec horn mtg flange thickness, the 12mm std length is really too short esp if you use a flat washer and lock washer. The next std length is 16mm. This length REQUIRES the use of both flat washer AND lock washer to avoid bottoming out on the driver magnet. I expect that a forceful bottoming will prove disasterous so it should be avoided.
I was able to find locally some nice, non-magnetic SS hardware that should work out nicely. Next step: install and quick listen prior to crude meas and subsequent Xover mods.
I was able to find locally some nice, non-magnetic SS hardware that should work out nicely. Next step: install and quick listen prior to crude meas and subsequent Xover mods.
Close Enough for Rock 'n' Roll.
O.K., I'm done, probably. :thmbsp:
Network is Eminence U-pxb2-800 with added notch filters:
1) Parallel trap C4, R1, L3, the basic compensation, substitues for LB1
2) Serial notch C5, R2, L4 flattens about 3 kHz
3) Serial notch C6, R3, L5 lowers the spike at 19 kHz
Inductor DCRs are provided.
Somebody with network optimization software can probably do better, but this will get you started using what you have.
I'm showing the final check I do to verify that the compensation is not significantly influenced by the L-Pad attenuation:
O.K., I'm done, probably. :thmbsp:
Network is Eminence U-pxb2-800 with added notch filters:
1) Parallel trap C4, R1, L3, the basic compensation, substitues for LB1
2) Serial notch C5, R2, L4 flattens about 3 kHz
3) Serial notch C6, R3, L5 lowers the spike at 19 kHz
Inductor DCRs are provided.
Somebody with network optimization software can probably do better, but this will get you started using what you have.
I'm showing the final check I do to verify that the compensation is not significantly influenced by the L-Pad attenuation:
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Redboy
a few good watts
Okay Zilch, can I use that as a parts shopping list? I'm thinking to get everything from PE. Mills resistors, the Dayton precision caps, and Jantzen inductors. Based on the values, I'm guessing these are what you've used. Oh, and Fastons - I assume they sell those, too. What size?
I haven't been able to get through to Assistance Audio - it keeps rolling into voicemail. Any experience with the other outfit?
I haven't been able to get through to Assistance Audio - it keeps rolling into voicemail. Any experience with the other outfit?
A search on eBay will bring up Assistance's store, and their BMS 4550 listing. No experience with the other outfit, but AA may give the same price upon inquiry.Redboy said:
Yes. I prototyped with Jantzen air core inductors, Mills wirewound non-inductive resistors, and Solen capacitors, all from Parts Express. Precision caps aren't required. C4 is 2 x 3 uF here, but 6.2 uF would likely work fine. DCR tells the inductor gauges I used.Redboy said:
It's an easy mod of that crossover, tying into the HF filter input in lieu of the overdrive protection light bulb(s), and onto the HF output for the rest. Simple to biwire with separate amps, as well. :thmbsp:
Mod's ~$42 per crossover, including their best (100W) L-Pad.
0.25" Fastons, looks like.
Note: Just added total system impedance measurement, above....
******
Anybody else heard these drivers on Altec 811B or 511A/B horns yet?
Flip the FR curve to view the requisite compensation. Compare to my voltage drive sim for this mod (the black one,) above.
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Redboy
a few good watts
At long last...
I've finally cobbled together the compensation. Tonight I had the chance to listen to these in my second listening room (the garage...) and I can already tell they are going to give my Forte's a run. It's hard to tell just how good it is in a crappy space like the garage, powered by an old Marantz with poor radio reception, but there were a few minutes during a piece on the local jazz station where I lost track of where the speakers were in the room. Sitting there with my eyes closed, I could swear there were instruments playing directly in front of me!
There is a bigger, broader, more enveloping tone to these giant horns that brings me in to the music in a way that my Forte's are always trying to. I know this is worth fine tuning.
It's not all good yet, though. I get some congested sounding stuff coming through at times. I'm hoping it can be resolved with better amplification, better space, more damping material and some final tweaking on the L-pads.
Here's a crummy picture of the crossover with compensation, taken in crummy light. What you're seeing is an Eminence 800hz crossover with HF compensation as spec'ed by Zilch a couple of posts back in this thread:
I've finally cobbled together the compensation. Tonight I had the chance to listen to these in my second listening room (the garage...) and I can already tell they are going to give my Forte's a run. It's hard to tell just how good it is in a crappy space like the garage, powered by an old Marantz with poor radio reception, but there were a few minutes during a piece on the local jazz station where I lost track of where the speakers were in the room. Sitting there with my eyes closed, I could swear there were instruments playing directly in front of me!
There is a bigger, broader, more enveloping tone to these giant horns that brings me in to the music in a way that my Forte's are always trying to. I know this is worth fine tuning.
It's not all good yet, though. I get some congested sounding stuff coming through at times. I'm hoping it can be resolved with better amplification, better space, more damping material and some final tweaking on the L-pads.
Here's a crummy picture of the crossover with compensation, taken in crummy light. What you're seeing is an Eminence 800hz crossover with HF compensation as spec'ed by Zilch a couple of posts back in this thread:
:thmbsp:
From what I can see, it looks right.
Having listened to these previously without the compensation, if the HF has now risen to the surface and floats effortlessly on top of the mids, it is working correctly.
Anybody have an RTA nearby? Best way to know is to measure.... :yes:
From what I can see, it looks right.
Having listened to these previously without the compensation, if the HF has now risen to the surface and floats effortlessly on top of the mids, it is working correctly.
Anybody have an RTA nearby? Best way to know is to measure.... :yes:
HEY!
That looks just like ZILCHLAB!
[And JackLab, and a bunch of other labs, too, I betcha....
: ]
Of potential interest and on topic, I found this reference recently:
http://db.audioasylum.com/cgi/m.mpl?forum=hug&n=82503&highlight=BMS+4550&r=&session=
Not sure, but I *THINK* we're in good company with the approach here.... :yes:
That looks just like ZILCHLAB!
[And JackLab, and a bunch of other labs, too, I betcha....
: ]Of potential interest and on topic, I found this reference recently:
Tom Danley said:
http://db.audioasylum.com/cgi/m.mpl?forum=hug&n=82503&highlight=BMS+4550&r=&session=
Not sure, but I *THINK* we're in good company with the approach here.... :yes:
Six of you eack kick in $50, y'all'll have one like Jackgiff's to share.... :yes:
Hey Redboy!
Looks to me you're working on home/reverse engineering a pair of M19's....
HF is definitely improved! I'll have to check with the local boys to see if there are any RTA's around. I'm guessing no.
Check it out...
Looks to me you're working on home/reverse engineering a pair of M19's....
Redboy
a few good watts
You'll have to ask Zilch about that... I'm just following directions!Looks to me you're working on home/reverse engineering a pair of M19's....
Zilch worked his magic, drew up a schematic, and I just cobbled the parts together. Things are sounding downright tasty! Boxes still need some extra damping I think, but it's hard to tell in the garage. Problem is I've got to rearrange the whole family room to make them fit in the system proper.
I assume you re-installed the loose port.... :yes:
Valencia on steroids.... :thmbsp:Looks to me you're working on home/reverse engineering a pair of M19's....
No wimpy-weenie 811B horns in THIS project, nope.... :nono:
:lmao:
Redboy
a few good watts
Oh yeah. I also cut the ports down to tune them properly.
I'm pretty sure that "congested" sound I referred to earlier is coming from the box, not the horn, so I'm hoping a little additional damping material will help.
These things are so sensitive that I'm only barely touching the very lowest end of the volume pot's travel on this 2275. I can hear that the two channels are a little unmatched in that range, and any extra noise coming through the receiver is very noticeable. That's good, as far as I'm concerned - I won't ever be driving them with much power.
