The BaSSlines (was High Sensitivity Design)

[dlneubec]

I only need the impedance to determine the precise transfer function of the passive elements. Once I have that I just calculate excursion vs frequency for the input voltage across this transfer function combined with the system parameters. You can easily do this now using my PCD and saving the midrange filter response as an frd file. Then model the driver in the Woofer and Box Designer and click the button to import the external filter (and make sure it is turned on with the other button). However, I would be glad to do this myself today for this driver using a simulated impedance (which will be close enough, since it is free air anyway) and I will use the same filter I had in the speaker you heard. I will send you the results later. I can't see any reason why it shouldn't work OK though.

What is your target sensitivity, Dan? There may even be other options too, but this should be a good mid for the design.

For Tweeters you might consider the Peerless HDS as an option.

Jeff

Sounds good Jeff. I'd like to see how the B&C mid looks in your simulation. As far as target sensitivity, at this point I see now reason not to try an approach what you were able to do (93db, I believe) in the Salk design. A little more might be better, a little less ok also.

Yes the Peerless HDS was one of the three tweeters I initially identified as candidates early in the thread (you might have missed that). They included:

Seas 29TFF/W (H1318, 92.5db: $44
Peerless HDS 810921, 93db: $78
Peerless DX25TG05-04, 93.5db: $28

http://www.madisound.com/catalog/product_info.php?manufacturers_id=149&products_id=1591

http://www.madisound.com/catalog/product_info.php?manufacturers_id=143&products_id=1744

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-578

These are well known and well tested, low distortion tweeters. All seem to be able to cross fairly low with Fs's below 1000Hz.

Here are a couple of long shot possibilies in the dome arena that Zaph has on his bench to test and are also high sensitivity with Fs around 1350hz. These are very inexpensive neo tweeters, so I don't have much hope for them though the rated sensitivity is quite high. Perhaps Zaphs testing will tell us the a bigger part of the story on these.

Vifa BC25SC06-04, 96db, $11.90
Vifa DQ25SC05-04, 94db, $15.60

http://www.madisound.com/catalog/product_info.php?products_id=8354

http://www.madisound.com/catalog/product_info.php?products_id=8352

[Mark Seaton]

Yes, I agree. The Audax is a very robust driver, and a very dynamic midrange. They rate it at 100dB, but in reality once the response is flattened it is only about 95dB, but hey, that's still very high. However, here's why it wouldn't work in my speaker, and it was the same reason for the B&C (at least the one I was going to use).

I made a really cool tool. I built together some aspects of my "Passive Crossover Designer" and my "Woofer and Box Designer" programs. This allowed me to model any driver; woofer, midrange, or tweeter by entering the T/S parameters, including Xmax, and the system parameters and model the T/S based transfer function. Then using the actual measured impedance I model the passive crossover circuit to get the transfer function of the crossover terminated by the impedance. Then I load this transfer function into the T/S model and enter the target power level. This allows me to see exactly how much power and at what frequency the driver will reach Xmax - whether it is a woofer, a midrange, or even a tweeter, based on the crossover it is used with.

The crossover I ended up with for this speaker was fairly demanding on the low end due to the dipole roll-off of the open baffle configuration. The listed Xmax of the Audax is only 0.5mm. My program showed that I reach this amount of travel with only 25 Watts of input. I realized from the simulations that I needed a driver that had at least 2mm of Xmax available if I wanted to remain linear to higher power level and avoid the distortion that comes with driving the coil out of the gap. The PHL was the only driver I could find that gave me the combination of linear, high resolution midrange reproduction, relatively low distortion, fairly decent sensitivity, and high enough excursion to meet demands. The PHL will not exceed its Xmax in this speaker until very high power levels. High enough that it probably won't matter at that point ;-)

Hi Jeff,

That's great you have extended the capability of your free design software to accomodate this modeling. LspCAD does this directly, and it is an immensely valueable feature. The observations you noted about the midrange are what I've been harping on for a few years now. The same problem extends even up into the tweeter realm when we explore lower crossover frequencies. Some lower frequency at some SPL will push the linear travel limits of most any driver, and the crossover and filtering have effects on this which can be both good and bad.

The modeling of the passive crossover WITH the modeled enclosure/driver is a further step of *system* engineering which not enough DIYers take a look at. A driver which looks great in isolation of a raw enclosure model might be a nightmare to get a working crossover with acceptable impedance and response or sensitivity. There are also some fun trade offs which can be made if you have a limited bandwidth application making non-obvious drivers very strong candidates... once the passive crossover is in place. I my designs I have the luxury of going one step further to actually specify the characteristics of the driver I'm after and have it built or find something close. In the few full range designs I have been working on this has afforded me the option of much lower crossover component counts and much fewer problems with impedance minimums. Anyone who has tried to passively cross a woofer over below 300Hz has probably run into this problem, but the same issues crop up with a midrange where you have the same relative proximity to the low frequency corner. This is most significant difference encountered when designing a passive vs. an active system, and is one reason I often recommend DIYers execute 3 way speakers with an active bass-midrange crossover. The likelihood of getting what you are after is much higher.

If you are ever feeling really ambitious (assuming your tool doesn't already allow this), add the ability to "drive" the physical parameters of the driver by way of cross calculating the according T/S parameter changes as you change Mms, Cms, Re & BL and even Sd. While LspCAD has its own quirks, this is one of its strong suits.

[Dennis H]

Dan in the newest version of SE in the enclosure designer is new feature that can apply generic filters to the box model. I use it to see the excursion of say, a 6" woofer that is crossed to a sub at 60hz or whatever. This is not precisely the same as Jeff's method I don't think. but it works well. It also helps to visualize how said 6" driver will sum with a woofer using the typical HT reciever bass managements settings.

WinISD Pro will do that too, add active filters. It won't give you accurate SPL curves for a dipole but it will give you accurate excursion curves if you know the transfer function and can cobble it together with active filters. As a first approximation for a dipole mid with 6dB baffle rolloff on the low end, you could try an electrical filter one order lower than the desired acoustical response -- 1st order filter for a 2nd order response.

[Mark Seaton]

WinISD Pro will do that too, add active filters. It won't give you accurate SPL curves for a dipole but it will give you accurate excursion curves if you know the transfer function and can cobble it together with active filters. As a first approximation for a dipole mid with 6dB baffle rolloff on the low end, you could try an electrical filter one order lower than the desired acoustical response -- 1st order filter for a 2nd order response.

Actually... That only gives you an approximation for the response. The excursion profile generally matches that of the driver in free-air or a huge sealed box for modeling purposes. You can then look at the excursion as it relates to Voltage input, and then work out the transfer function of IB frequency response to dipole.

[Dennis H]

Actually... That only gives you an approximation for the response.

Yeah, I think I said that.

[Mark Seaton]

Yeah, I think I said that.

Oops... I guess is mis-interpreted. It wasn't clear (to me ops: ) if you were suggesting that the 1st order high pass was intended to model the excursion and not the frequency response. I see now I just mis-read. :T

[Dennis H]

No problem, I confuse myself all the time. Here's a pic for anyone else I've confused.

[nickmckinney]

Electrovoice used to say....without high efficiency there is no accuracy. I still remember their marketing quote from the 70's. I guess that dates me a little.

I have to jump on John J.'s bandwagon here - the Lambda woofers he is making are very special drivers, capable of doing things that most drivers can not begin to touch. For example their ability to reach deep in the bass with a good Xmax, and at the same time maintain extremely low non-linear distortion values into the midrange are pretty much unprecedented. The 12" I used had the Le of 4" driver and had a flat response on-axis to 2.5kHz. The Lambda will give you bass slam and a low distortion mid that can cross effectively to a dedicated midrange that you will not get with hardly any other woofer.

Funny thing you bring up Electrovoice, I used to rebuild them frequently and used what I learned from their cone shape for the TD driver design.

The first Lambda driver started life as a Kicker extended pole motor, solid copper tube idea came from an early Scanspeak, and a cone profile shape like the EV18 (just smaller) all mixed together - without the dustcap of course. Every woofer I tested sounded a LOT better before the cap was glued on so I decided to find a way to do without. It became an amazing heatsink as well when the solid phase plug was cooked up.

After working around so many different variations of the same basic design, for it to sound like real music it has to be efficient IMHO.

Back to your regularly scheduled debate...................

Nick McKinney
TD papa

[nickmckinney]

A few things you will see different in the future. We measure parameters using 1/3 of the surround, so you will see the Sd and as a result the 1w/1m efficiency be spec'd a little lower than in the past. Regarding Xmax, Nick previously published just the physical overhang as Xmax. This was back when DUMAX testing became the craze and before the 70% rest Bl point became significant. The TDM for example has 3.3mm physical overhang. It however has a very tall 3/4" thick gap plate. If you look at the BL curve of the driver you have over 6mm of travel before you get to that 70% value. The S, H, and X all have just over 10mm physical overhang and again looking at a BL curve they have over 14mm before the Bl drops to 70%. As these numbers based on BL curves are basically the standard now days, we will be publishing those now.

John

What he said. If anything I shortchanged many of the specs to be conservative back in the day.............

[Jeff B.]

Hi Jeff,

That's great you have extended the capability of your free design software to accomodate this modeling. LspCAD does this directly, and it is an immensely valueable feature. The observations you noted about the midrange are what I've been harping on for a few years now. The same problem extends even up into the tweeter realm when we explore lower crossover frequencies. Some lower frequency at some SPL will push the linear travel limits of most any driver, and the crossover and filtering have effects on this which can be both good and bad.

The modeling of the passive crossover WITH the modeled enclosure/driver is a further step of *system* engineering which not enough DIYers take a look at. A driver which looks great in isolation of a raw enclosure model might be a nightmare to get a working crossover with acceptable impedance and response or sensitivity. There are also some fun trade offs which can be made if you have a limited bandwidth application making non-obvious drivers very strong candidates... once the passive crossover is in place. I my designs I have the luxury of going one step further to actually specify the characteristics of the driver I'm after and have it built or find something close. In the few full range designs I have been working on this has afforded me the option of much lower crossover component counts and much fewer problems with impedance minimums. Anyone who has tried to passively cross a woofer over below 300Hz has probably run into this problem, but the same issues crop up with a midrange where you have the same relative proximity to the low frequency corner. This is most significant difference encountered when designing a passive vs. an active system, and is one reason I often recommend DIYers execute 3 way speakers with an active bass-midrange crossover. The likelihood of getting what you are after is much higher.

If you are ever feeling really ambitious (assuming your tool doesn't already allow this), add the ability to "drive" the physical parameters of the driver by way of cross calculating the according T/S parameter changes as you change Mms, Cms, Re & BL and even Sd. While LspCAD has its own quirks, this is one of its strong suits.

Thanks for the thumbs up. Yes, I can manually change those parameters in my version if I need to. However, most of us are usually modeling known drivers.
Jeff B.

[Jeff B.]

Funny thing you bring up Electrovoice, I used to rebuild them frequently and used what I learned from their cone shape for the TD driver design.

The first Lambda driver started life as a Kicker extended pole motor, solid copper tube idea came from an early Scanspeak, and a cone profile shape like the EV18 (just smaller) all mixed together - without the dustcap of course. Every woofer I tested sounded a LOT better before the cap was glued on so I decided to find a way to do without. It became an amazing heatsink as well when the solid phase plug was cooked up.

After working around so many different variations of the same basic design, for it to sound like real music it has to be efficient IMHO.

Back to your regularly scheduled debate...................

Nick McKinney
TD papa

Nick, allow me to be one of the guys that says "Good job!" on the driver design. It allowed me to produce a truly stellar performer for Jim Salk. Thanks.
Jeff B.

[Jeff B.]

Sounds good Jeff. I'd like to see how the B&C mid looks in your simulation. As far as target sensitivity, at this point I see now reason not to try an approach what you were able to do (93db, I believe) in the Salk design. A little more might be better, a little less ok also.

Yes the Peerless HDS was one of the three tweeters I initially identified as candidates early in the thread (you might have missed that). They included:

Seas 29TFF/W (H1318, 92.5db: $44
Peerless HDS 810921, 93db: $78
Peerless DX25TG05-04, 93.5db: $28

http://www.madisound.com/catalog/product_info.php?manufacturers_id=149&products_id=1591

http://www.madisound.com/catalog/product_info.php?manufacturers_id=143&products_id=1744

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-578

These are well known and well tested, low distortion tweeters. All seem to be able to cross fairly low with Fs's below 1000Hz.

Here are a couple of long shot possibilies in the dome arena that Zaph has on his bench to test and are also high sensitivity with Fs around 1350hz. These are very inexpensive neo tweeters, so I don't have much hope for them though the rated sensitivity is quite high. Perhaps Zaphs testing will tell us the a bigger part of the story on these.

Vifa BC25SC06-04, 96db, $11.90
Vifa DQ25SC05-04, 94db, $15.60

http://www.madisound.com/catalog/product_info.php?products_id=8354

http://www.madisound.com/catalog/pro...oducts_id=8352

Dan, the B&C model you are thinking about looks very good in the simulation. I will send you an email with a graph in it later. If you don't already have it I will include a pdf of the driver's specs and response. I will also check with Jim and see how much info he is comfortable with me sharing with you. After all, he really liked your Soundrounds and might want some omni assistance down the road. :W

[Dennis H]

Wow, Nick's back! I'm glad your legacy is living on with John building the drivers. :T

[dlneubec]

Dan, the B&C model you are thinking about looks very good in the simulation. I will send you an email with a graph in it later. If you don't already have it I will include a pdf of the driver's specs and response. I will also check with Jim and see how much info he is comfortable with me sharing with you. After all, he really liked your Soundrounds and might want some omni assistance down the road. :W

Hi Jeff,

That's good to hear that there is potentially another workable midrange option. We'll have to discuss it more after I see your results. Earlier today I emailed you pdf's of 3 different 6.5" B&C mids to look at, so I probably already have it. Are you still getting email at your Insight mailing address? I know they have changed over to Comcast and some mailing addresses have changed.

When you talk with Jim, be sure to tell him I'd be thrilled to help in any way I can if he decides to do something with an omni. I wish he could have heard me HOSS design as well. I know Dennis liked it very much at Iowa.

[Dennis H]

I just found the K&T test of the 1120 on AVS. Distortion at 105dB looks pretty nice.

Image not available

[nickmckinney]

Guys, honestly tell me how much you are willing to pay for a high end midrange these days. I was working on making a new version of the Western Electric/Altec 8" some time back but the truth is it costs as much to build an 8" as it does a 12" especially since the quantity is much lower. Few people thought it was viable at $250 a pop so I shelved it........

[Mark K]

Guys, honestly tell me how much you are willing to pay for a high end midrange these days. I was working on making a new version of the Western Electric/Altec 8" some time back but the truth is it costs as much to build an 8" as it does a 12" especially since the quantity is much lower. Few people thought it was viable at $250 a pop so I shelved it........

Well,

I think once you go north of ~$200 you start losing buyers. However, a genuinely high end mid, 7-8" with extremely good construction, sensitivity and on/off axis specs would fill a niche. You could always test the waters with a group buy...

[looneybomber]

Guys, honestly tell me how much you are willing to pay for a high end midrange these days.

There are quite a few capable mids for not too much over 100.00 and you can always use more than one. But for an equally capable tweeter, you have to spend quite a bit and you can't use multiples. If you could develop a (non compression) tweeter capable of 120db@1m (with low distortion) for around 200-250 it'd sell!

[John_E_Janowitz]

It's funny that Nick and I had similar plans/goals for introducing similar drivers just at different periods in time and arrived at them for different reasons. One midrange driver that interested me was the Davis Acoustics 20TK8 8" Kevlar Alnico Driver.

http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=297-574

http://www.partsexpress.com/imageslarge/297-574L.jpg Image is still here.

Quite a nice driver, low inductance, high efficiency, well behaved cone/surround, etc, but at the $415 price range wasn't a viable option. I started thinking about what I could do that would be similar but have the characteristics of the Lambda TD woofers. I actually got as far as to get pricing quotes on a few grades of alnico, machine some T-yokes and top plates, and even sample a coil.

Then someone had come to me asking about a replacement/upgrade/redesign of something like the WE/Altec 755C. The goal was to do something with similar qualities, but make it low distortion, higher xmax, and higher sensitivity. The initial goal was actually for an underhung design, 3/8" thick gap and 1/8" long coil. About 3.3mm Xmax. Some issues with miscommunication brought that venture to a halt, but the parts are still here.... hmmmm

John

[dlneubec]

Jeff has taken a look at 3 of the B&C 6.5" midrange drivers, the 6ndl38 (neo), 6mdn44 (neo) and the 6md38 and it looks like the best candidate to replace the PHL 1120 might just be the 6md38 at $88.79 at Parts Express. That is a substantial savings over the PHL at $159.50, if indeed it does not result in a significant loss in performance.
6md38

At this point I'm leaning toward trying B&C 6md38 with the Lambda TD12H or TD12X. I'm not sure which, but leaning toward the TD12X since it has a little higher sensitivity without seemingly sacrifincing much at the low end.
lambda drivers
John J., do you have any thoughts about which driver I should go with?

Since there would be some substantial savings on the mid with this combination, it may be apropriate to go for a little nicer tweeter, which maybe pushes the Peerless HDS to the front of the pack. These are listed at $78 each, but out of staock at Madisound and at $59.50 at Meniscus, but I'm not sure if it is in stock there or not. The total driver cost with this combination comes out just over $765 for the pair (using Meniscus HDS price). Not too bad, IMO and could be a VERY high bang for the buck system.
Peerless HDS@Mad
Meniscus

Any thoughts?

[dlneubec]

Then someone had come to me asking about a replacement/upgrade/redesign of something like the WE/Altec 755C. The goal was to do something with similar qualities, but make it low distortion, higher xmax, and higher sensitivity. The initial goal was actually for an underhung design, 3/8" thick gap and 1/8" long coil. About 3.3mm Xmax. Some issues with miscommunication brought that venture to a halt, but the parts are still here.... hmmmm

John

Sounds like and interesting driver John. Are you considering pursuing it?

[Jonasz]

Dan, why not go with a MTM with something like the Seas ER18? Should give you a sensitivity around 94dB and a lot more area, xmax and along with that more freedom with crossover to the 12". They're of course not dedicated mids but...

[JoshK]

You could always do the B&C 6MD38 in MTM too for the ~ same price as the PHL 1120 for MT.

[dlneubec]

Hi Jonasz,

That solution would certainly work, but it would be a completely different speaker than the one I heard that inspired this design, the Bagby/Salk design. That is the typical HiFi driver solution and brings with it both the benefits and drawback of the two mid driver concept. The Bagby/Salk concept, using a pro mid, did not lack anything in the midrange to any HiFi speaker I've heard, many with 2 mids.

Also of great importance to me is the size of the speaker. An open baffle mtm solution would require making the speaker much taller to fit the second M. It would have to be wider on the top section, since the wider open baffle width would have extend up past the top M and could not be tapered as in my conceptual design. The taper is intended to reduce the visual impact of the speaker's mass in the room, by making it larger on the bottom and smaller on the top.

[augerpro]

Still going to use a waveguide?

[dlneubec]

Not sure about the waveguide, but if I do it will be a shallow 1/2" to 3/4" deep one like Zaph proposed for the D26 and I used in my Duo designs. It will probably come down to which tweeter I end up with and how it tests it in the WG.

[ttan98]

Jeff, Dan or anyone who may want to comment the following:

The AE 12" woofer maybe out of reach for most people as the price I believe is little high even though it has the quality that may attach to it. I came across an alternative from Beyma which may act as a substitute.


Beyma 12BR70

T&S parameters are:

Resonant Frequency (fs) 35Hz
Impedance (Re) 5.6 ohms
Coil Inductance (Le) 1.0 mH
Mechanical Q (Qms) 1.89
Electrical Factor(Qes) .44
Total Q (Qts) .36
Comp. Equivelant Vol. (Vas) 4.77 ft3 / 135 Liters
Voice Coil Overhang (Xmax) 6.0 mm
Reference Efficiency 1.2%
Displacement Volume 340 cm3

[ttan98]

Further to my previous post,

1. Price=$125 from US speakers
2. Initial design Bass Reflex, Vb=90l, Fb=38hz

Has very low distortion, visit this site for more info.

http://www.usspeaker.com/beyma%2012BR70-1.htm

view under Beyma, 12BR70.

any comments welcome.

[John_E_Janowitz]

The Beyma could be a viable option if you are on a budget. It really depends on what your goals are for the system, how loud and low you wish for it to play. Response wise in the 90L 38hz enclosure it looks similar to the TD12X, but that is about where I would end the similarities.

You would need 2 of the Beyma to reach the same levels as from one of the TD12X while operating within Xmax. I don't see any mention of shorting rings in the Beyma driver which is a huge part of what makes the Lambda non-linear distortion so low. The Beyma is half the price of a TD12X, but also less than half the Xmax, about 1/4 the power handling, less useable bandwidth, etc. With the dustcap and rubber surround you can expect some kind of resonance lower in frequency than with the Lambda's phase plug and hand treated foam surround.

It's funny because we're offering a driver that is really different than almost everything out there. It's somewhat in a price point where there aren't a lot of other drivers. It's a little high for many of the DIY guys. Then there are the guys who are using the the woofers to replace $1000 TAD woofers who can't believe a woofer 1/3 the price can be anywhere near as good or better. That is until they hear them anyway. I will say that a large part of our cost is materials though. Nearly every part is sourced from in the US to control the quality and repeatability of parts. That isn't always cheap.

John

[nickmckinney]

Jeff, Dan or anyone who may want to comment the following:

Beyma 12BR70

Coil Inductance (Le) 1.0 mH

And that is where the similarities really end. It will sound like any other cheap woofer in the midbass compared to a TD driver. Very few people seem to understand that having a large internal filter creates phase shift in the operating range, then understand that this inductance spec is taken at low levels for the test and at high levels it is most likely highly non linear.

[dlneubec]

ttan98,

I did look at all the Beyma woofers and the one you mention just did not come close to meeting the design goals in this case. It requires a considerably larger box than the Lambda TD12H, which was a non-starter for me.

For a less expensive alternative, according to my research, I'd look next at the Ciare 12.00 ndw1 at $174 each or perhaps a pair of Dayton ST-255 10" series 2 woofers at about $123 for a pair. The Beyma 10BR60 is not too bad at $99 for a less sensitive option.

[dlneubec]

The Beyma could be a viable option if you are on a budget. It really depends on what your goals are for the system, how loud and low you wish for it to play. Response wise in the 90L 38hz enclosure it looks similar to the TD12X, but that is about where I would end the similarities.

You would need 2 of the Beyma to reach the same levels as from one of the TD12X while operating within Xmax. I don't see any mention of shorting rings in the Beyma driver which is a huge part of what makes the Lambda non-linear distortion so low. The Beyma is half the price of a TD12X, but also less than half the Xmax, about 1/4 the power handling, less useable bandwidth, etc. With the dustcap and rubber surround you can expect some kind of resonance lower in frequency than with the Lambda's phase plug and hand treated foam surround.

It's funny because we're offering a driver that is really different than almost everything out there. It's somewhat in a price point where there aren't a lot of other drivers. It's a little high for many of the DIY guys. Then there are the guys who are using the the woofers to replace $1000 TAD woofers who can't believe a woofer 1/3 the price can be anywhere near as good or better. That is until they hear them anyway. I will say that a large part of our cost is materials though. Nearly every part is sourced from in the US to control the quality and repeatability of parts. That isn't always cheap.

John

Hey John or Nick,

What is the easiest way to get a pair of TD12H (4ohm version) ordered? Do you accept PayPal by any chance?

Dan

[Kevin Haskins]

Just for kicks and VSAC I'm doing a Eminence Alpha 6 build along with a B&C compression driver on a horn. The bottom-end is active so the entire project is designed to work with 300Bs, and a set of Class D amps driving the bass cabinet.

The only high efficiency 6.5" drivers I've measured are the Eminence prototype (it has a different cone than the stock Alpha) and the B&C 6PEV13. The B&C was more efficient, but had a much more ragged response than the Eminence and the distortion numbers climbed quickly on the low-end. Not surprising because they don't really have much of a surround.

I like the Eminence better and it's half the price.

[augerpro]

Dan did madisound give you an ETA on the 810921? I need to order a couple to finish my 5.1 setup

[dlneubec]

Brandon,

I ordered mine from Meniscus, because they still had a limited number in stock at only $59.50 versus $78 at Madisound.

[dlneubec]

Just for kicks and VSAC I'm doing a Eminence Alpha 6 build along with a B&C compression driver on a horn. The bottom-end is active so the entire project is designed to work with 300Bs, and a set of Class D amps driving the bass cabinet.

The only high efficiency 6.5" drivers I've measured are the Eminence prototype (it has a different cone than the stock Alpha) and the B&C 6PEV13. The B&C was more efficient, but had a much more ragged response than the Eminence and the distortion numbers climbed quickly on the low-end. Not surprising because they don't really have much of a surround.

I like the Eminence better and it's half the price.

Kevin, I have ordered my Peerless HDS and I'm in the process of ordering the Lambda's, but the mid is still something I can change. What is this Eminence prototype you mention and where did you see it?

I looked at the B&C 6PEV13 and it did not look to good as a match to the other drivers and had very little Xmax, as I recall. I expect to need around 2mm as a minimum. The B&C 6MD38 has all the right specs and the FR doesn't look too bad, but I'm willing to check out any other pro mids, that is until I place an order :B

[nickmckinney]

Hey John or Nick,

What is the easiest way to get a pair of TD12H (4ohm version) ordered? Do you accept PayPal by any chance?

Dan

Did John get a hold of you yet?

[nickmckinney]

Sounds like and interesting driver John. Are you considering pursuing it?

I can answer that since I am talking with the person that owns the cone mold:

YES

I have guinea pigged my original Altec 755A cone to be analyzed for the material by the cone maker that made it 50 years ago and still has the mold on the shelf. Translation to that it I have just spent the first $400+ since the driver was worth at least that much from what I see lately and is now about worthless without a cone.............

The original 755 covered about 60-12Khz give or take, I don't see why we can't duplicate that with more excursion, power handling, and sensitivity. This is a design I have been wanting to do for years now as it solves the issues of what to mate to a TD driver.

[dlneubec]

Did John get a hold of you yet?

Yes.

[Kevin Haskins]

Kevin, I have ordered my Peerless HDS and I'm in the process of ordering the Lambda's, but the mid is still something I can change. What is this Eminence prototype you mention and where did you see it?

I looked at the B&C 6PEV13 and it did not look to good as a match to the other drivers and had very little Xmax, as I recall. I expect to need around 2mm as a minimum. The B&C 6MD38 has all the right specs and the FR doesn't look too bad, but I'm willing to check out any other pro mids, that is until I place an order :B

It's an OEM product but it shouldn't be much different than the standard Alpha 6A that you can buy at Parts Express.

[FlorianO]

PHL 1120 alternative ?

Hello all,

Does anyone know (or venture a comment) on how the new 6.5'' ScanSpeak Illuminator compares with the PHL 1120 ?

That driver really looks to be "born for OB" . Details here

TIA,

Florian

[A9X]

Hello all,

Does anyone know (or venture a comment) on how the new 6.5'' ScanSpeak Illuminator compares with the PHL 1120 ?

That driver really looks to be "born for OB" . Details here

TIA,

Florian

Efficiency is very low, about 86dB across most of it's operating band based on the published curves. I see no advantage to this driver as an OB MR over several of the Pro drivers or the PHL.

[mayhem13]

Really the question of tweeters to mte with looms in my mind. I've aquired 4 B&C 8NDL51s for an MTM design and the only tweeters that really have my thoughts are the Ciares, particularly the PT383. Could someone take a look on the Ciare site and give some informative feedback- i unfortunatley am not bilingual.

[dlneubec]

Mayhem,

Wow, I hope you can find something with a better looking FR. Their published data shows a very broad, 5-6db dip from about 3khz to 10khz.

[terryj]

Hi Dan

first off, thanks for the luvverly pic of how the speakers may look, I might steal some of that look if it's OK with you!! (tho would you mind redoing it so I can see how to make a box with an 18 inch woofer in it look nice?? heh heh)

I understand the attraction of the sound you heard, I too run PHLs in an active system, the dynamics are great. One thing on the 'to try' list is running the mids open baffle, my current PHL mids (1660) are probably not suited for OB (don't go low enough) but I also have a set of 1360's that should be able to handle it.

I cross to sealed PHL 18's.

Anyway, I didn't jump into your thread to talk about mine (other than indicate I understand your quest) but rather I have a practical question to ask all of you.

It's all well and good to read manufacturers specs on sensitivity etc, but surely (depending on the x-over chosen etc) the final product sensitivity can be a bit hard to calculate?

So, just how does one go about finding out the actual final sensitivity of the speakers in the room?

Do many people actually do this? or just rely on some 'rule of thumb' calculations based on published specs.

I guess I'm asking (and would love to find out the actual sensitivity of mine as well) how will you see if you have achieved your goal of a high sensitivity design unless you measure the sensitivity, and could someone enlighten me as to the procedure.

Maybe it is a bit more tricky in a tri amped system??