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The BMS group buy thread!!! - Page 6

post #151 of 492
Quote:
Originally Posted by Raul GS View Post

What are the advantages (if any) of using BMS 4550 16 ohm vs 8 ohm with the AE TD15M 8 Ohm driver?

The sensitivity of the 16 ohm CD will be closer to the woofer then the 8 ohm CD therefore it requires less padding to level match the drivers.
post #152 of 492
Quote:
Originally Posted by mtg90 View Post

When I have the drivers here for Jake's SEOSR design I was planning on dropping a TD15M into the Sentinel enclosure I have and design a crossover for it and the SEOS-12/DNA-360. If you want you can ship a 4550 over here and I can pop that CD in and design a crossover around that one as well. Unless someone closer has a 4550 they would not mind sending over for design purposes.

I would be more than happy to ship the 4550 over to you. I'm thinking the TD15m/SEOS12/4550 combo is going to be a killer.
post #153 of 492
Thread Starter 
Sounds like another nice way to go with these combos.

Matt, how do you think the TD15/4550 combo will compare to the Sentinel design??
post #154 of 492
Quote:
Originally Posted by mtg90 View Post

The sensitivity of the 16 ohm CD will be closer to the woofer then the 8 ohm CD therefore it requires less padding to level match the drivers.
Would the 4550 16 ohm work better with the TD12X than the 8 ohm?
Thanks
Chris
post #155 of 492
Given that the sensitivity of the TD12X is lower then that of the TD15M, I would say yes.
post #156 of 492
Quote:
Originally Posted by ChopShop1 View Post

Sounds like another nice way to go with these combos.

Matt, how do you think the TD15/4550 combo will compare to the Sentinel design??


I am not sure, the TD15 is no doubt a better driver then the B&C used in the sentinel however so was the JBL 2226 and I had a hard time hearing much of a difference between them. I will be really interested to hear how the 4550 sounds compares to the 360.
post #157 of 492
What makes the 4550 better than the DE250? It appears to go lower, but that could simply be based on the horn it was attached to for the measurements. If you put a DE250 on a deeper horn, it will look like it could be crossed over lower as well.

From what I've read and tested, higher power ratings (for the same general diaphragm size) normally get into material that can handle more heat or use thicker material. Those materials can give more 'listener fatigue' as you go up the chart. Mylar, phenolic, Kapton polyimide films, other polyesters....titanium, etc.

Power handling on any of these similar CD's isn't worth comparing for home audio because it's never going to be maxed. Even differences of 100hz aren't worth comparing on these CD's. Instead of looking at going up in power handling or down 100hz on a deeper horn, I would think it makes the most sense to be going down to a lighter diaphragm material that might sacrifice power handling for over all sound quality in a home environment.

Personally I think most would prefer the sound of a beefed up DE10 that used a mylar diaphragm, could safely be crossed around 1000hz, and with a modest power rating. Basically something between the DE10 and the DE250 that blends things from both. I'd be looking to get a smoother sound, not more power handling with possibly harsher materials.
Edited by Erich H - 2/26/13 at 12:17pm
post #158 of 492
Quote:
Originally Posted by Jack Arnott View Post

I think the reason for the drop below 800hz on the product page is due to the horn, not the driver. I have used these drivers to 800hz with good results.
I have some customers who have used them lower, but I know they may not meet power or distortion specs below this point.
This is also the case with the 4552. It is rated to 1Kz, not 800hz, even though they both have the same VC (voice coil) and membrane. The reason is that the 4552 is a smaller driver (neo vs. ceramic magnets) and the 4552 opens up faster to get to the 1" throat size.
So it has more distortion below 1Khz.

In answer to your last question. All BMS drivers are a ring radiator diaphragm design, the B&C is a full dome diaphragm.
As such, the VC on the BMS only has to control a very small length of diaphragm at any one point.
It also gives less room on the BMS diaphragm for break up, or standing modes. Also, since the VC is in the center of the diaphragm, and not ringing the outside, even though they both have 1.75" VCs, the BMS will have more diaphragm surface area.

So you will get better transient response, less over ring, and higher sensitivity from the BMS.

In my opinion, generally speaking, the B&C drivers will have a flatter frequency response, the BMS will have better dynamics, and a more detailed and smoother sound.

Regards, Jack Arnott
Assistance Audio
This was the quote when asked what the 4550 offers over the 250 or 360. Specifically the part that starts with "in answer to your last question".
Chris
post #159 of 492
Quote:
Originally Posted by Erich H View Post

What makes the 4550 better than the DE250? It appears to go lower, but that could simply be based on the horn it was attached to for the measurements. If you put a DE250 on a deeper horn, it will look like it could be crossed over lower as well.

From what I've read and tested, higher power ratings (for the same general diaphragm size) normally get into material that can handle more heat or use thicker material. Those materials can give more 'listener fatigue' as you go up the chart. Mylar, phenolic, Kapton polyimide films, other polyesters....titanium, etc.

Power handling on any of these similar CD's isn't worth comparing for home audio because it's never going to be maxed. Even differences of 100hz aren't worth comparing on these CD's. Instead of looking at going up in power handling or down 100hz on a deeper horn, I would think it makes the most sense to be going down to a lighter diaphragm material that might sacrifice power handling for over all sound quality in a home environment.

Personally I think most would prefer the sound of a beefed up DE10 that used a mylar diaphragm, could safely be crossed around 1000hz, and with a modest power rating. Basically something between the DE10 and the DE250 that blends things from both. I'd be looking to get a smoother sound, not more power handling with possibly harsher materials.

Erich,

These sentiments were taken from another forum.
Quote:
How do you feel 4550 and DE250 compare, assuming you've tried them on the same horns/WG?
Quote:
The DE250 is smoother, the 4550 has more extension. I am not sure if I have any measurements comparing them on the same WG. I will look.

Another thing is that the 4550 can have a sharp resonance spike at c. 19hHz. I found it doesn't appear on every waveguide.
Quote:
Blue trace = mini Smith horn
Red trace = ~3kHz wood conical horn with OS-throat (has constant directivity AFAICT)
Green trace = K-Tube


That being said, most have recommended crossing the 4550 up higher at around 1k-1.2k. They mention the TD15m sounds much better up in this range than the 4550 does.
post #160 of 492
Thread Starter 
Quote:
Originally Posted by bass addict View Post

Erich,

These sentiments were taken from another forum.




That being said, most have recommended crossing the 4550 up higher at around 1k-1.2k. They mention the TD15m sounds much better up in this range than the 4550 does.

That's pretty interesting. It seems like most of these designs have plenty of extension, and smooth is certainly sought after.
post #161 of 492
I have a question for the group.
Why is the 4550 the only 1" driver by BMS that is ever mentioned on this forum?

I much prefer the 4552 myself.
And the 4538 and 4540 have advantages also.

But again, 4550 is the only one mentioned.
post #162 of 492
I don't know for sure...but I think it has to do with that it is a good match for the seos 12. Bolt pattern, exit angle, etc.
post #163 of 492
I also think it's the exit angle. My understanding is the SEOS 12/15 (not sure about other sizes) was designed for 14 deg. Based on some info I found on another site it looks like the 4550 and the 4540 have 14 deg exit angles which match up with the SEOS. What's the preference between those two and why?

Here is some info I found on another site. Not sure how accurate it is.
4524 20º
4538 21.8º
4544 20.6º
4550 14º
4554 26.7º
4555 30º
4590/4590p 1º
4591 1º
4540nd 14º
4552nd 24º
4592nd 10º
4594nd 3º
4595nd 10.8º
post #164 of 492
Thanks.
Did you switch 4592 and 4594?
The 4594 and 4595 should be almost identical.

The difference between the 4540 and 4550 is the first has a 1.5"/60W Voice Coil (VC) and the second has a 1.75"/80W VC.
The 4540 is neo magnet, and the 4550 is ceramic magnet. The 4540 is a single wound VC, and the 4550 is double wound (both inside and outside the former).

The 4540 goes down about an octave higher than the 4550, but is much lighter and also goes 1/2 octave higher.
The 4540 has a higher flux density, and stabler flux variation due to the neo magnet.

The 4540 is thread mount, and the 4550 is two bolt mount.

It is interesting to me what details are picked up on, and others not so much.
And also what is focused on in certain threads or projects.
Throat angle is not mentioned much in most of my dealings. But then, most casual users don't have access or control of the throat angle of their horns.
Usually this is something asked by only the most detailed and proprietary horn builders.

I once lent a person a 4550 and a 4552. I later told him the reason they had different frequency responses was because of the different throat angles.
He argued with me that they were the same. And you point out the differences. Thanks again.
post #165 of 492
Quote:
Originally Posted by mtg90 View Post

When I have the drivers here for Jake's SEOSR design I was planning on dropping a TD15M into the Sentinel enclosure I have and design a crossover for it and the SEOS-12/DNA-360. If you want you can ship a 4550 over here and I can pop that CD in and design a crossover around that one as well. Unless someone closer has a 4550 they would not mind sending over for design purposes.

If I send you a 4552 would you also design a crossover for that?

Also, if Bass Addict is waiting for his 4550 with this shipment, I will supply one of those. I doubt I am any closer to you than he is.

Regards, Jack
post #166 of 492
Quote:
Originally Posted by Jack Arnott View Post

If I send you a 4552 would you also design a crossover for that?

Also, if Bass Addict is waiting for his 4550 with this shipment, I will supply one of those. I doubt I am any closer to you than he is.

Regards, Jack

That would be awesome. If the 4552 is worth the price difference in sound quality, I'd jump on it instead.
post #167 of 492
Jack, what do you prefer about the 4552? They have almost identical FR's and the 2nd and 3rd harmonics are pretty close. My understanding is that they are pretty close to the same short of the neo magnet. Of course I'd generally prefer neo for pro use, but it doesn't matter much in the home.

My experience (and that of a few others who are well respected)is that two non-titanium CDs, on the same horn, both playing over their comfortable range, EQd to identical targets are nearly indiscernible. Of course people rarely compare them like that and instead it is in different rooms or with different horns or with crossovers designed by different people.

The SEOS12/15 was originally designed for the DE250 because it is the most widely available, moderately priced and well tested CD used in home speakers. We also knew the 4550 had an almost identical throat exit angle so that gave us two very high quality CDs for people to choose from (IIRC the Beyma CP380 and Radian 465 also match well). Obviously, people can use any 1" 2 bolt CD they want. The key is that part of the SEOS premise is to have a CD exit to throat transition that minimizes diffraction and transitions smoothly into the SEOS profile. How much this matters is debatable.

The other BMS options were not considered because they either didn't play low enough or they were thread-on style.

I don't know what exit angles the SEOS-24 or smaller SEOS horns are designed for. You really only have the 4594nd and 4593nd to choose from anyway.
post #168 of 492
Has anybody tried the 4547nd? Neo motor, 1" throat, 1.75" vc and BMS rates it down to 1.2k. They're priced about the same as the 4550. I've Googled them but the only documented experience I've found is a pro sound guy in England......I'd imagine they'd play down to 1k just fine for all but the most hardcore SPL guys. Nice thing is they're damn small (less than 3.5" dia) if you need something with a small form factor like I do.
post #169 of 492
Quote:
Originally Posted by coctostan View Post

Jack, what do you prefer about the 4552? They have almost identical FR's and the 2nd and 3rd harmonics are pretty close. My understanding is that they are pretty close to the same short of the neo magnet. Of course I'd generally prefer neo for pro use, but it doesn't matter much in the home.

agreed.... sound quality for home use rules the day. If there is an audible difference between the two and it's for the better on the neo version, then it might justify their $101 premium per driver ($148 vs. $249 MSRP prices). Otherwise, the ceramic magnet weight difference won't matter to me on a speaker that won't be moved around a lot. I'm happy to pay if it results in better sound to my ear when 1-2 good watts get applied (as with their efficiency and my listening levels, I doubt the CD would ever see more than 2 watts).... The key for me is finding detail without introducing harshness and ringing. I can flavor with the electronics and cables if it comes to that...

I've now wired up a bunch of different iterations of seos12 designs using the DE250/DNA360/etc. drivers (as well as played a little bit with a couple active cross implementations) and have a feel for the strengths in the sound they produce. I've not heard the BMS stuff before and am curious to hear how it compares. So I paid my money for some 4550s in addition to the big coaxial CDs I'm ordering for my big horn project and we'll see if they produce a sound I like more, less, or I don't notice a difference at all... Reading opinions about it on the internet unfortunately won't replicate actually hearing them in my room with my electronics. So rather than try to line up auditions elsewhere, I'll put the money up and play with it here. I'll either be happy or will take a bath selling nearly new stuff later on smile.gif
post #170 of 492
Doc, you lost me on "cables". smile.gif

Take a look at the measurements of the two drivers. I don't think my ear is golden enough to distinguish.

Like I said before, same room, same horn, EQ'd to same exact response with DBT and I'd put money on nobody knowing the difference. You can even swap in ultra low inductance silver cables. biggrin.gif
post #171 of 492
Quote:
Originally Posted by Jack Arnott View Post

If I send you a 4552 would you also design a crossover for that?

Also, if Bass Addict is waiting for his 4550 with this shipment, I will supply one of those. I doubt I am any closer to you than he is.

Regards, Jack


Sure I don't mind doing one for that CD too, it may be interesting to see what differences the exit angle makes on the SEOS-12 and how noticeable I find them.
post #172 of 492
Quote:
Originally Posted by coctostan View Post

Doc, you lost me on "cables". smile.gif

Take a look at the measurements of the two drivers. I don't think my ear is golden enough to distinguish.

Like I said before, same room, same horn, EQ'd to same exact response with DBT and I'd put money on nobody knowing the difference. You can even swap in ultra low inductance silver cables. biggrin.gif

I'm wondering if the same can be said in regards to the DNA360 vs 4550. For me it's not so much of a price difference, but an availability issue. Erich likes to sell the SEOS12's with the 360's so getting just a SEOS would probably take a lot more time.
post #173 of 492
Quote:
Originally Posted by coctostan View Post

...Like I said before, same room, same horn, EQ'd to same exact response with DBT and I'd put money on nobody knowing the difference. You can even swap in ultra low inductance silver cables. biggrin.gif

I agree, how about this acronym? "MDLW"... lol. I mentioned I used Lynk silver hookup cable on my xo's and bwaslo rolled his eyes, but I swear that's all I had! tongue.gif I'll have to admit though, there was some "wank" factor using it! Anyway...

I've got the 360 and 4550 on hand and plan to test both with the seos-12 and seos-at1. I'll do 3 measurement method and summed response for the overlay feature in PCD for the final xo optimization, but will ultimately have accurate acoustic measurements for each CD. I'll be using OM and DATS, I may dabble a bit in lspCAD, but more comfy with PCD at the moment. My guess is the response will be nearly identical, but there will be some differences in shaping between the two (this may or may not be the audible part). I'm planning to build a passive for the final speaker, but for testing between the two, active in box measurements would be easier to compare the two and less costly for development. I don't have the seos-at1 yet, but have the enclosure, cd's, and seos-12's ready. Spring can't come soon enough!
post #174 of 492
Quote:
Originally Posted by Nate Hansen View Post

Has anybody tried the 4547nd? Neo motor, 1" throat, 1.75" vc and BMS rates it down to 1.2k. They're priced about the same as the 4550. I've Googled them but the only documented experience I've found is a pro sound guy in England......I'd imagine they'd play down to 1k just fine for all but the most hardcore SPL guys. Nice thing is they're damn small (less than 3.5" dia) if you need something with a small form factor like I do.

Ohh, I had kind of forgotten about these. And the 4545.

OK, I am going to make a bold prediction. That is the 4545 is going to be close to the 14 degree exit angle.

Alright, not that bold. I was surprised at first to see that the 4540 has such a less steep angle than the 4538, then realized that the 4540 is much longer, with the thread mount front.

Depth of drivers and their exit angles: (remember the 4540 and 4538 are a smaller Voice Coil, so they are perhaps expanding from a different place.)

Driver depth exit angle
4538 40mm 21,8º
4540 45mm 14º
4544 47mm 20.6º
4545 48mm
4547 35mm
4550 52mm 14º
4552 36mm 24º

So based on this i am going to SWAG 16.5º for the 4545, and 25º for the 4547.

The 4547 has a three bolt pattern. The 4545 has a thread mount, and of course the 4550 and 4552 have the same two bolt pattern that the horns were built for.
And the 4545 is more money than the 4547. (tradeoffs, tradeoffs, tradeoffs.)

So to go with the 4545 or 4547, you would need to get an OK from Erich, and make the horns different.
(It is conceivable that you could drill your own holes for the 4547.)
post #175 of 492
Quote:
Originally Posted by Nate Hansen View Post

Has anybody tried the 4547nd? Neo motor, 1" throat, 1.75" vc and BMS rates it down to 1.2k.

And why is it rated to only 1.2Khz?

With the 4552, it is easy to see the spike in distortion at 900hz vs. the 4550. I don't see any such things on the 4545/47.
post #176 of 492
Quote:
Originally Posted by coctostan View Post

Jack, what do you prefer about the 4552? They have almost identical FR's and the 2nd and 3rd harmonics are pretty close. My understanding is that they are pretty close to the same short of the neo magnet. Of course I'd generally prefer neo for pro use, but it doesn't matter much in the home.

My experience (and that of a few others who are well respected)is that two non-titanium CDs, on the same horn, both playing over their comfortable range, EQd to identical targets are nearly indiscernible. Of course people rarely compare them like that and instead it is in different rooms or with different horns or with crossovers designed by different people.

Short answer, the 4552 has a higher flux density.

This is because with neo you can focus the power in the gap more. But there is a bit more than that to it.
As mentioned with the coax drivers, neo has the potential to have less flux variation over the power band.
And this is how one of the design engineers at BMS use it. So I am told. There is really no data, or sheets to show it.

I do know that I sent some drivers to a guy to measure and listen to. It turns out that he was using EV drivers.
He said the neo and ceramic from EV sounded identical. I am guessing EV voiced them the same (flux density), so that they could sell replacements, to people that were using their vintage gear.
Just a guess, no real knowledge.

For me the difference is dynamics. In a listening test we did over 12 years ago, I had just purchased some td-1's. We tried the 4548 vs the driver in them.
(This was before neo magnet BMS, or double wound Voice Coils.)
One of the most revealing things was pointed out by a drummer that was there. (I tend to listen to vocals first.)
He showed that with the BMS you could hear the drum stick hit the ride cymbal, and with the stock driver you couldn't. The frequency response had nothing to do with it.
post #177 of 492
So here's what I propose.
I have already had a couple of emails asking if it is too late to upgrade to the 4552.
And it is kind of on my word that this would be happening. A lot of decisions, without a lot to go on. (It was kind of an idle question I threw out yesterday, not a challenge.)
I think it would better serve us all if we keep with the 4550, with the possibility to upgrade. Here is how it would work.
I picture fewer people going with the 4552.45, or 47, in the end. So we ship all the 4550s to Erich as planned.
In the mean time, have the passives built, and get the first impressions from MTG90.
I'm guessing that if people wanted to, after that, they could have the demo crossovers and drivers shipped to them to listen.
I can send a 4552, 4545, and 4547 to MTG90, along with an adapter that will get them to two bolt pattern. (These are over $20ea, and available, but I'm guessing you can get them cheaper else where, I sell virtually none of these.)

Then, if people want to upgrade, they can. And I will pay Erich to send the left over 4550 to me.
The down side for me is that I will be making extra shipments. The up side is that I forgot I have to order 1" drivers in quantities that the boxes come in, so there might be extra 4550 anyway.
And you all (potentially) get exactly what you want/need/can afford.

I need to run, I will finish this out more later, or better answer any questions that might be left dangling.
post #178 of 492
Quote:
Originally Posted by Jack Arnott View Post

And why is it rated to only 1.2Khz?

Just going on what BMS says in their specs. FWIW I'm using the 4524's now way lower than the spec'd 1.9khz and at sane (avg 65-70dB) apartment levels they're fine. Can't say I'd like to push them though.

The BMS site shows a 2-bolt version of the 4547nd as well.
post #179 of 492
Quote:
Originally Posted by robotbunny View Post

I agree, how about this acronym? "MDLW"... lol. I mentioned I used Lynk silver hookup cable on my xo's and bwaslo rolled his eyes, but I swear that's all I had! tongue.gif I'll have to admit though, there was some "wank" factor using it! Anyway...

I've got the 360 and 4550 on hand and plan to test both with the seos-12 and seos-at1. I'll do 3 measurement method and summed response for the overlay feature in PCD for the final xo optimization, but will ultimately have accurate acoustic measurements for each CD. I'll be using OM and DATS, I may dabble a bit in lspCAD, but more comfy with PCD at the moment. My guess is the response will be nearly identical, but there will be some differences in shaping between the two (this may or may not be the audible part). I'm planning to build a passive for the final speaker, but for testing between the two, active in box measurements would be easier to compare the two and less costly for development. I don't have the seos-at1 yet, but have the enclosure, cd's, and seos-12's ready. Spring can't come soon enough!

With a passive it is harder to get them quite as exact in response. To do a comparison I would want to use a DSP so they can be a closer match. I'd still say the differences will be small enough that telling which is which will be tough let alone which is better.
Quote:
Originally Posted by bass addict View Post

I'm wondering if the same can be said in regards to the DNA360 vs 4550. For me it's not so much of a price difference, but an availability issue. Erich likes to sell the SEOS12's with the 360's so getting just a SEOS would probably take a lot more time.

I don't think Erich sells the SEOS-12 contingent upon buying a DNA-360.
Quote:
Originally Posted by Jack Arnott View Post

Ohh, I had kind of forgotten about these. And the 4545.

OK, I am going to make a bold prediction. That is the 4545 is going to be close to the 14 degree exit angle.

Alright, not that bold. I was surprised at first to see that the 4540 has such a less steep angle than the 4538, then realized that the 4540 is much longer, with the thread mount front.

Depth of drivers and their exit angles: (remember the 4540 and 4538 are a smaller Voice Coil, so they are perhaps expanding from a different place.)

Driver depth exit angle
4538 40mm 21,8º
4540 45mm 14º
4544 47mm 20.6º
4545 48mm
4547 35mm
4550 52mm 14º
4552 36mm 24º

So based on this i am going to SWAG 16.5º for the 4545, and 25º for the 4547.

The 4547 has a three bolt pattern. The 4545 has a thread mount, and of course the 4550 and 4552 have the same two bolt pattern that the horns were built for.
And the 4545 is more money than the 4547. (tradeoffs, tradeoffs, tradeoffs.)

So to go with the 4545 or 4547, you would need to get an OK from Erich, and make the horns different.
(It is conceivable that you could drill your own holes for the 4547.)

I don't see the point of going with either driver over the 4550.
Quote:
Originally Posted by Jack Arnott View Post

And why is it rated to only 1.2Khz?

With the 4552, it is easy to see the spike in distortion at 900hz vs. the 4550. I don't see any such things on the 4545/47.

If I had to guess it would be due to how each driver's diaphragm handles excursion. It looks like the 4550, whether due to the different motor or a different diaphragm can handle the demands below 1khz better thus the lower distortion. It looks like the 4545 is similar. It likely just has less xmax.
post #180 of 492
Quote:
Originally Posted by coctostan View Post

...I don't know what exit angles the SEOS-24 or smaller SEOS horns are designed for. You really only have the 4594nd and 4593nd to choose from anyway.

Here it is...SEOS-24 angle is 14 degrees, jzagaja posted the angle: http://www.diyaudio.com/forums/group-buys/166312-waveguides-horns-111.html#post3016740 Great thread, lots of good Auto-Tech with various CD experimentation.

Here's another post from jzagaja, measurements with SEOS-15 and 4550: http://www.diyaudio.com/forums/group-buys/166312-waveguides-horns-84.html#post2777955
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