Identifying Legitimately High Fidelity Loudspeaker: The Drivers

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admin

Audioholics Robot
Staff member
This article focuses attention on loudspeaker drivers while continuing the series on Identifying Legitimately High Fidelity Loudspeakers. We take you on a tour of all the various aspects in driver design and the trade-offs associated with each type. We discuss why budget minded designs often employ stamped frame baskets as opposed to better but more costly cast frame alternatives. We also go into more detail on driver mechanics to gain a better understanding of what's inside the loudspeaker driver to make it work. Getting a peek at the guts inside a speaker system you are considering purchasing can tell you a lot about the budget allocated towards the drivers in the design. If the manufacturer doesn't supply such images, it doesn't hurt to ask. Better parts truly can yield better performance in the hands of a competent designer which are more common these days with the advent of inexpensive measurement equipment and knowledge of the basics in loudspeaker mechanics 101.


Discuss "Identifying Legitimately High Fidelity Loudspeaker: The Drivers" here. Read the article.
 
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S

shadyJ

Speaker of the House
Terrific article! Very informative, thanks for writing it. So far in the series for "Identifying Legitimately High Fidelity Loudspeakers", we have articles on cabinets, cross overs, drivers, and cost-cutting, will there be more in this series? Drivers, cross overs, and cabinets are mostly what a loud speakers is composed of. Whatever the case, I enjoy these articles and am looking forward to more like them.

I have a question though, pertaining to the tweeters, what is the mechanical difference between the compression drivers used in high sensitivity speakers and normal tweeters. I take it it is a matter of design more than material?
 
gene

gene

Audioholics Master Chief
Administrator
Terrific article! Very informative, thanks for writing it. So far in the series for "Identifying Legitimately High Fidelity Loudspeakers", we have articles on cabinets, cross overs, drivers, and cost-cutting, will there be more in this series? Drivers, cross overs, and cabinets are mostly what a loud speakers is composed of. Whatever the case, I enjoy these articles and am looking forward to more like them.

I have a question though, pertaining to the tweeters, what is the mechanical difference between the compression drivers used in high sensitivity speakers and normal tweeters. I take it it is a matter of design more than material?
thanks. As you could imagine, these articles take quite a lot of effort and time to write. Each time it went through a peer process from the folks I selectively chose to peer it based on their expertise, it caused me to refine and add stuff. Designers all have their own preferences, and biases (myself included). I tried my best to find a happy medium for all. I plan on writing 2 more articles in the series (one dealing with audio theories, and the other as a wrap up). Don't hold you're breath as I have a lot on my plate and I don't particularly look forward to writing about such a broad topic like this.

I didn't get too into detail on various tweeter types such as horns but the principles are still the same. A horn basically provides a passive method of providing a more efficient coupling path between the speaker and air. It's also useful in controlling both vertical and horizontal directivity. I may expand on this Driver article in the future or get one of our writers to do it for me if I can't find the energy to do so myself :D
 
P

PENG

Audioholic Slumlord
thanks. Each time it went through a peer process from the folks I selectively chose to peer it based on their expertise, it caused me to refine and add stuff. Designers all have their own preferences, and biases (myself included). I tried my best to find a happy medium for all.
I think peer process is great, for reasons you cited. Sometimes we see forum members quoting things they read on the www as though they are facts while quite often those are opinions expressed/regurgitated by others, often mixed with some facts and many are naturally biased. Peer review process certain helps to present a more balanced view and minimize the chance of misunderstood, or over exaggerated "facts and opinions.

I plan on writing 2 more articles in the series (one dealing with audio theories, and the other as a wrap up). Don't hold you're breath as I have a lot on my plate and I don't particularly look forward to writing about such a broad topic like this.
I hope it will still be more on loudspeakers as aside from the quality of the media source itself they are the weak link of today's hifi equipment in my opinion.
 
gtpsuper24

gtpsuper24

Full Audioholic
Both drivers are 5.25" the one on the left is a more expensive speaker and the cast alloy driver on the right is a cheaper speakers. I think when some say theres no difference in stamped or cast, I think that has to do more with the driver technology not being good enough to take advantage of cast baskets. The top frame on the stamped basket actually bent as I was screwing it back in to place with just a hand screwdriver :eek: Not very good for a $500 bookshelf.
 

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slipperybidness

slipperybidness

Audioholic Spartan
Good article. I really would have liked some info on ribbon tweeters, planar transducers, maybe even electro-stats. Perhaps an update to the article down the line.
 
GranteedEV

GranteedEV

Audioholic Ninja
Nice article. Would have liked a little bit more on flux modulation and also the benefits on custom-woven diaphragm materials, if you ever do update it :D

I have a question though, pertaining to the tweeters, what is the mechanical difference between the compression drivers used in high sensitivity speakers and normal tweeters. I take it it is a matter of design more than material?
Think of a compression tweeter, as being basically a large dome (or even a ring radiator) with an oversized magnet / voice coil with all the output being "compressed" into a smaller exit along with a phase plug (when I say phase plug, think of KEF's "tangerine waveguide", not seas' copper pokey thing)

Because a 1" exit compression tweeter uses a larger, probably 1.75" or 2" diaphragm, it's a lot more prone to audible issues from diaphragm material highlighted in this article. The few smaller diaphragm compression tweeters (IE 1.4" diaphragm) don't normally play well below ~1.8khz or so but might be cleaner in the upper treble; all else the same.

A 1.5" exit compression tweeter will often have a 3" diaphragm... Likewise, a 2" exit compression tweeter will probably use a 4" dome. As you probably can figure, a 4" dome is probably not going to be pistonic up to tweeter frequencies (with the exception of TAD or JBL's beryllium stuff). So these are best used with a crossover to a super tweeter! But having one driver cover 300hz to 8khz, does have its advantages.

The horn in front of the compression tweeter will be a big contributor in terms of impulse response and sound power response. There're horns optimized for high SPLs, and others that provide little "boost" but plenty of directivity control.

Basically - compression drivers are probably more sensitive than 1" domes to the material used simply because they're bigger. what's more, many are made strictly for pro audio use, so diaphragm durability can be favored over sound quality. Custom versions of these drivers for home use IMO is a lot of untapped potential.
 
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GranteedEV

GranteedEV

Audioholic Ninja
Gene, I just read the last page on tweeters, and I'm a bit unclear on something.

However, there are no free lunches and the designer needs to be mindful that doing so does NOT lower the resonance frequency of the tweeter. Thus, care must be taken NOT to lower the crossover point within the region of the drivers Fs.

The tweeter resonance frequency is a critical metric in determining where to set a loudspeaker’s crossover frequency.
It seems to me that the argument being made here, is that the resonant frequency in and of itself, is "bad".

As far as I can tell, a tweeter that is 8db down in level at resonance acoustically, would "physically" only be asked to be "18db" down assuming, say, the waveguide/horn adds 10db of acoustic gain. So you're not really compromising power handling or linearity.

It seems to me, that the resonance frequency, assuming the driver has a sufficiently low Q at resonance, does not contribute negatively in such a manner that "avoiding it" is the goal. I think using the tweeter fs to determine crossover frequency is flawed... the fs is almost an arbritrary number as far as I see, as far as the final loudspeaker is concerned. I'd say the article itself showed how you can "artificially" lower fs of a sub-par tweeter. While there's some correlation, i think it's a red herring to imply causation of the idea that fs is itself the source of distortion.
 
gene

gene

Audioholics Master Chief
Administrator
Gene, I just read the last page on tweeters, and I'm a bit unclear on something.



It seems to me that the argument being made here, is that the resonant frequency in and of itself, is "bad".

As far as I can tell, a tweeter that is 8db down in level at resonance acoustically, would "physically" only be asked to be "18db" down assuming, say, the waveguide/horn adds 10db of acoustic gain. So you're not really compromising power handling or linearity.

It seems to me, that the resonance frequency, assuming the driver has a sufficiently low Q at resonance, does not contribute negatively in such a manner that "avoiding it" is the goal. I think using the tweeter fs to determine crossover frequency is flawed... the fs is almost an arbritrary number as far as I see, as far as the final loudspeaker is concerned. I'd say the article itself showed how you can "artificially" lower fs of a sub-par tweeter. While there's some correlation, i think it's a red herring to imply causation of the idea that fs is itself the source of distortion.
Every major loudspeaker engineer that has peer reviewed this article have all agreed that you typically want to crossover a tweeter one octave above Fs. Using a shallow horn does add efficiency, but it doesn't change Fs so you would still have to cross it over pretty close to the same frequency you would have had to without the horn loading. I am sure there are designers successfully using the Fs bump as part of their crossover design, but now you're operating a tweeter down to its lowest usable limit and potentially straining it and increasing distortion while lowering power handling.

This tweeter for example is arguably one of the best 1" domes ever made and used in countless high end designs:
http://www.scan-speak.dk/datasheet/pdf/d2905-950000.pdf

It's Fs is 550Hz and nobody would ever use it down that low. Most speakers I've seen implementing this tweeter, cross it over at 2kHz (2 octaves above Fs).
 
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AmFuzzy

AmFuzzy

Audiophyte
ScanSpeak

Every major loudspeaker engineer that has peer reviewed this article have all agreed that you typically want to crossover a tweeter one octave above Fs. Using a shallow horn does add efficiency, but it doesn't change Fs so you would still have to cross it over pretty close to the same frequency you would have had to without the horn loading. I am sure there are designers successfully using the Fs bump as part of their crossover design, but now you're operating a tweeter down to its lowest usable limit and potentially straining it and increasing distortion while lowering power handling.

This tweeter for example is arguably one of the best 1" domes ever made and used in countless high end designs:


It's Fs is 550Hz and nobody would ever use it down that low. Most speakers I've seen implementing this tweeter, cross it over at 2kHz (2 octaves above Fs).

Thanks for pointing out Scan-Speak. I have a couple of speakers using this tweeter and it's phenomenal. I'm amazed at how many "high-end" speaker companies use inferior actual drivers and use bizarre cabinet designs to offset their inability to build proper drivers or buy from Scan-Speak or Vifa. I'd love to see real world tests of drivers in some of these so called "high-end" speakers. Driver vs. driver capabilities. I know crossovers and cabinet design all come to play here...but with simpler designs and high quality drivers can a more budget speaker compete with some of these ridiculous high priced speakers? Here's a good example of quality without the price. norh_com/Norh_Loudspeaker/Norh_9.html
 
D

DS-21

Full Audioholic
Nice article. Would have liked a little bit more on flux modulation and also the benefits on custom-woven diaphragm materials, if you ever do update it :D
Also, less misinformation on those pointy polepiece extensions the article erroneously calls phase plugs would have been nice.

Here's a post by Andrew Jones (KEF/Infinity/TAD-Pioneer) about those things with actual information.
Andrew Jones said:
With regard to phase plugs on bass/mid drivers, I was always very sceptical regarding claimed improvements in off axis performance. So I did the experiment!
I measured a typical polypropylene cone/dustcap driver, both on axis and at 15 deg off axis increments out to 60 deg.
I then plotted the change in response at each angle compared to on axis. This is then a measure of the directivity response of the driver.
Next I removed the dustcap and re-measured the on axis response. Of course, this was messed up because without the dustcap, we have a cavity resonance formed by the tubular well formed by the voice coid former and top of the pole piece.
Next I fashioned a fixed "phase plug" to fill this cavity, the top end of the plug sitting level with the start of the cone.
I then remeasured all the on and off axis responses. The on axis response was now much closer to that of the driver with the dustcap, reduced in level almost 1dB due to the lower effective area having removed the dustcap, but the basic response was quite simliar to the one with dustcap.
However, the change between off axis and on axis was identical, within closer than 0.5dB, to the dustcap version out to beyond 7 or 8kHz.
Extending the phase plug even further out made no noticable changes to the directivity response, and only marginal changes to the on-axis response.
The conclusion is that a so-called phase plug has no real effect on driver directivity, especially so for a midrange driver that will be crossed over to a tweeter.
Source.
David Smith (JBL, KEF, Snell) also commented on that thread to the same effect, but without providing empirical evidence.

To be a phase plug, it would have to cover substantially all of the radiating surface. Here's an example of a real phase plug for a cone driver, by EAW.


Every major loudspeaker engineer that has peer reviewed this article have all agreed that you typically want to crossover a tweeter one octave above Fs.
Yet many top-tier designs don't do that. Fact of the matter is, the way to choose a crossover point is by matching directivity of the woofer in the intended crossover region. A smart designer picks parts according to that. (See Linkwitz Labs for a discussion on why he chose his various HF drivers.) A dumb designer tries to shoehorn parts together without thinking about the things that are actually important.

Using a shallow horn does add efficiency, but it doesn't change Fs so you would still have to cross it over pretty close to the same frequency you would have had to without the horn loading.
Nope. The relevant physical factor here is not Fs, but excursion. A loaded driver has to move less for a given SPL at a given frequency than an unloaded driver. And a 1" dome just doesn't have much radiating area. Soft domes like the Scan also suffer from lower excursion limits, because the diaphragm will deform if pushed further. (That's why most modern domes are rigid.)

But it can be done, if excursion is kept in check, even with a soft dome. For example, David Smith's big Snells used the old Audax neo soft dome, with an Fs of aroudn 1500Hz) down to ~2.5kHz. (He also used a bespoke annular phase plug - again, note that a real phase plug covers substantially all of the drive unit's radiating surface.) The crossover point was chosen, as in all competently-designed speakers, based on directivity concerns. And he couldn't do those speakers (per his Stereophile interview) until that tweeter came out. Why? Nothing else prior to the little Audax was compact enough for his innovative "eXpanding Array" configuration with sufficient volume displacement for the design.


(As an aside, Dan Wiggins also went gaga over those Audax tweeters when they came out ca. 1999 or so.)

This tweeter for example is arguably one of the best 1" domes ever made and used in countless high end designs:
http://www.scan-speak.dk/datasheet/pdf/d2905-950000.pdf

It's Fs is 550Hz and nobody would ever use it down that low. Most speakers I've seen implementing this tweeter, cross it over at 2kHz (2 octaves above Fs).
First, nothing special about that old ScanSpeak part, especially by modern standards. Second, the reason it's not typically crossed over low is because of excursion concerns. Fs is not a major factor.

It's simple math: in the case of the old Scan 9500, what's the volume displacement of a driver with 8.5 cm^2 Sd and 0.4mm xmax?
 
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Send Margaritas

Send Margaritas

Audioholic
Great article Gene. I truly enjoyed that, and pinned it to my favorites to read again a time or two.

Thanks very much!
 
gene

gene

Audioholics Master Chief
Administrator
Also, less misinformation on those pointy polepiece extensions the article erroneously calls phase plugs would have been nice.

Here's a post by Andrew Jones (KEF/Infinity/TAD-Pioneer) about those things with actual information.

Source.
David Smith (JBL, KEF, Snell) also commented on that thread to the same effect, but without providing empirical evidence.

To be a phase plug, it would have to cover substantially all of the radiating surface. Here's an example of a real phase plug for a cone driver, by EAW.




Yet many top-tier designs don't do that. Fact of the matter is, the way to choose a crossover point is by matching directivity of the woofer in the intended crossover region. A smart designer picks parts according to that. (See Linkwitz Labs for a discussion on why he chose his various HF drivers.) A dumb designer tries to shoehorn parts together without thinking about the things that are actually important.



Nope. The relevant physical factor here is not Fs, but excursion. A loaded driver has to move less for a given SPL at a given frequency than an unloaded driver. And a 1" dome just doesn't have much radiating area. Soft domes like the Scan also suffer from lower excursion limits, because the diaphragm will deform if pushed further. (That's why most modern domes are rigid.)

But it can be done, if excursion is kept in check, even with a soft dome. For example, David Smith's big Snells used the old Audax neo soft dome, with an Fs of aroudn 1500Hz) down to ~2.5kHz. (He also used a bespoke annular phase plug - again, note that a real phase plug covers substantially all of the drive unit's radiating surface.) The crossover point was chosen, as in all competently-designed speakers, based on directivity concerns. And he couldn't do those speakers (per his Stereophile interview) until that tweeter came out. Why? Nothing else prior to the little Audax was compact enough for his innovative "eXpanding Array" configuration with sufficient volume displacement for the design.


(As an aside, Dan Wiggins also went gaga over those Audax tweeters when they came out ca. 1999 or so.)



First, nothing special about that old ScanSpeak part, especially by modern standards. Second, the reason it's not typically crossed over low is because of excursion concerns. Fs is not a major factor.

It's simple math: in the case of the old Scan 9500, what's the volume displacement of a driver with 8.5 cm^2 Sd and 0.4mm xmax?
I know Andrew Jones very well and he's a great engineer. Not all loudspeaker designs agree on all aspects of speaker design. Hence why there is such a diversity of product options and driver technologies on the market. There can be many benefits of phase plug drivers,not just off-axis but as a way to reduce turbulence as I mentioned in the article.

Fs is an important factor when determining the crossover frequency of a system and nobody will play a tweeter down to Fs but how it handles an octave above it does matter. As for nothing being special about the Scan Speak 9500 tweeter, I am sure literally dozens of pro designers and DIY types would disagree as to this day, it's still revered as one of the best soft dome tweeters ever produced. Incidentally some of the top loudspeaker designs still use this tweeter in their products.

The content in my article is solid and I know you enjoy sparring with folks in the forum but it's not something I have the time or desire to do with you, especially seeing how you often misquote people's research. Recall the most recent case regarding Dr. Floyd Toole and how he had to correct you in the Velodyne thread about measurement resolution and averaging frequency response curves.
 
monkish54

monkish54

Audioholic General
I know Andrew Jones very well
Dr. Floyd Toole and how he had to correct you in the Velodyne thread
MAAAAN! Why don't I get to call up Toole and Jones (I do have his phone number, as he gave me his card, but I'm not actually gonna call and bug him). I'm very very jealous Gene! Ask Dr. Toole if he wants to give me a tour of Harman in Northridge. :p I live so close...yet still so far (since I can't actually go in.). :(

Oh, also, tell Dr. Toole Monkish54 says "You're the ****!" LOL :D
 
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D

DS-21

Full Audioholic
I know Andrew Jones very well and he's a great engineer. Not all loudspeaker designs agree on all aspects of speaker design.
This isn't a matter of "agreement," it's a matter of conclusory assertions - which, you may recall, I called you on in my comments on the pre-release article - being utterly destroyed by data.

Speaking of data, may I post the relevant section of the email you sent me when I called you on this point while you still had a chance to get rid of the misinformation due to my feedback on the article prior to release?

Hence why there is such a diversity of product options and driver technologies on the market. There can be many benefits of phase plug drivers,not just off-axis but as a way to reduce turbulence as I mentioned in the article.
That's silly. Heat-sinking, maybe. Styling, definitely. Anything else? A big fat no. ("Turbulence?" Please!)

And, as Mr. Jones showed, pointy pole-piece extensions - I won't mislabel them "phase plugs," just as I won't call the phase plugs used to change the shape of the tweeter wavefront in Tannoy and KEF concentric drivers "waveguides," even though both firms' propaganda departments use that word rather than the correct term. Words mean things. - reduce efficiency by lowering radiating area.

The content in my article is solid
It has some interesting historical tidbits, like the stuff about stamped frames bending due to the weight of bucking magnets not accounted for in their original design. But there isn't much there there beyond the historical color. I mean, to spend as much time as you do on demonstrably false claims about silly polepiece extensions and not even mention Faraday shielding?

and I know you enjoy sparring with folks in the forum but it's not something I have the time or desire to do with you, especially seeing how you often misquote people's research.
One can't "misquote' when one's quote consists of the quote in full and provides a source the the original discussion.

Your implication that I misquoted Mr. Jones is simple intellectual dishonesty, Gene. And the record is cited in my post, for anyone who believes my interpretation is wrong.

For that matter, please give us one example of me "misquoting" someone's research.

Recall the most recent case regarding Dr. Floyd Toole and how he had to correct you in the Velodyne thread about measurement resolution and averaging frequency response curves.
I see that exchange quite differently from the way you characterize it, but I'll leave that point at that.
 
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gene

gene

Audioholics Master Chief
Administrator
This isn't a matter of "agreement," it's a matter of conclusory assertions - which, you may recall, I called you on in my comments on the pre-release article - being utterly destroyed by data.

Speaking of data, may I post the relevant section of the email you sent me when I called you on this point while you still had a chance to get rid of the misinformation due to my feedback on the article prior to release?



That's silly. Heat-sinking, maybe. Styling, definitely. Anything else? A big fat no. ("Turbulence?" Please!)

And, as Mr. Jones showed, pointy pole-piece extensions - I won't mislabel them "phase plugs," just as I won't call the phase plugs used to change the shape of the tweeter wavefront in Tannoy and KEF concentric drivers "waveguides," even though both firms' propaganda departments use that word rather than the correct term. Words mean things. - reduce efficiency by lowering radiating area.



It has some interesting historical tidbits, like the stuff about stamped frames bending due to the weight of bucking magnets not accounted for in their original design. But there isn't much there there beyond the historical color. I mean, to spend as much time as you do on demonstrably false claims about silly polepiece extensions and not even mention Faraday shielding?



One can't "misquote' when one's quote consists of the quote in full and provides a source the the original discussion.

Your implication that I misquoted Mr. Jones is simple intellectual dishonesty, Gene. And the record is cited in my post, for anyone who believes my interpretation is wrong.

For that matter, please give us one example of me "misquoting" someone's research.



I see that exchange quite differently from the way you characterize it, but I'll leave that point at that.
As I said in my last post, I don't have the time or desire to debate your misinformed opinions.

Here is an example where you had to be shot down by the source himself Dr. Floyd Toole for misquoting him.

http://forums.audioholics.com/forums/851537-post94.html

I think a week break from our forums is in order for you.

Next time bring your concerns to me in a PM rather than trying to publicly discredit my work or those that have peer reviewed my work.

BTW, I sent my article to Andrew Jones for a read over and asked him to provide any comments he felt were incorrect about how I represented phase plugs.

His preliminary response was to let me know that phase plug drivers do in fact offer benefits though his findings didn't indicate they did so to control directivity. Since he is a person of authority (like the others that peer reviewed my article) and not a keyboard commando, I will happily make alterations to the article if he brings me any points needing to be changed.
 
W

wzort

Audiophyte
great article. I have a question...and I just can't find an answer....

I am a speakeraholic. I have 4 JBL 4311s stacked 2 per side..WTTW. I have 4 Original Advents, stacked WTTW, I have recapped pair of stock DQ10s and a second pair which has been modified, and is a test bed....ribbon tweeters, new midwoofers, etc. Frankenspeakers. I am an Advent masointe-surround woofer refoamer. Same driver as the DQ10, yes. I tinker. Here is my issue. Every Advent woofer i have come across has had a felted cone and dustcap. Sealed...for a sealed box speaker. Kinda makes sense. I just picked up a pair of these Advent woofers with see thru, porous fabric dust caps. I thought this material was only used in open box, bass reflex designs, and that it would be inappropriate for a sealed box cabinet. So......, maybe someone refoamed these a decade back, and unknowinglyput on a larger than stock, wrong material dust cap....Or did Advent help out a VC overheating problem by "front venting" by a design modification to a breathable fabric cap ? Should I remove this cap and replace it with a felt one ? leave it be ? I want to restore and improve the sound of these old speakers ( recapping, etc)...not degrade it. I have 2 pairs...one pair with felt DC, the other with fabric? What should I do ? Thanks.
 
L

Lvnsnfnatk

Audiophyte
This was a well written article. I'm glad I found it. There is so much to understand in design. I have a question regarding my home setup and I hope this is the place to ask such a question.

I need some help with my Mirage M1Si's. They're a bipolar design incorporating what was once considered a unique tweeter design "Si". They're 20 years old and I can hear something is wrong with them - perhaps a bad voice coil that can be heard on certain pieces of music at a certain volume level.

I opened the bottom of this tall speaker to look inside. It isn't easy to get to the guts of this speaker but what I could see inside made me pause. I saw cheap, zip cord type wiring running from the crossover to the back of the speakers. The connection to the individual speakers (there are approx 6 drivers in each enclosure) was also shoddy. The speaker units themselves also looked like Radio Shack cheepo models, the type you'd see inside the door panel of a given factory car system. Small magnets on the back of each driver, even the woofers! These speakers were not inexpensive. At the time they were selling for $6,600/pair. I'm thankful I didn't pay that amount. I have them bi-wired using old MIT MH-770 Bi-wire as well. There is a Linkwitz-Reilly crossover inside that appears to be passive (no power). I'm not a speaker designer, just an audiophile. BTW, the Linkwitz-Reilly guys are still in the business of designing x-overs.

After seeing how crummy the guts of this was and not wanting to take out a second mortgage, I had considered replacing the individual speaker units themselves with more robust components that would include rewiring them with quality OFC wire that is shielded, replacing the cheap looking crossover with more worthy board material. There has to be someone who can do that job. I'd then somehow reassemble the speaker so it will maintain its structural integrity - rigidity. Your article helped me to understand that this might be a difficult job locating the right speakers for the design of this monitor and then combining them to sound right using the speaker's stock range considering the science you described. I knew going in it wasn't going to be a simple R&R, but now i'm having second thoughts.

Until my hard drive crashed a while back, I had a speaker company willing to take on the job, but I lost their information with their approach and since cannot find a company via a Google search since I don't know anyone around here to tackle it. High end audio is on the decline since the CD is being forced out. I really love the 360º sound and large sound stage of this speaker (in a bright room with just a throw rug) that at times can be very detailed through my Levinson with tight, accurate bass and a nice midrange.

You are a knowledgeable guy and have a great style of writing - I laughed while reading some of your comments. Thanks for taking the time to write this informative piece, you really inspired me to try this again.
 
Swerd

Swerd

Audioholic Spartan
My general advice to you is If It Ain’t Broke, Don’t Fix It. Leave the individual drivers, the internal wiring, and the crossovers as they were built. If something is wrong, it should be identified as much as possible, and repaired. Otherwise, listen to your speakers. Don’t judge their sound by looking at them – especially inside.
I need some help with my Mirage M1Si's. They're a bipolar design incorporating what was once considered a unique tweeter design "Si". They're 20 years old and I can hear something is wrong with them – perhaps a bad voice coil that can be heard on certain pieces of music at a certain volume level.
If you hear “something wrong” only on certain pieces of music and at a certain volume level, it probably isn’t a bad voice coil. Can you describe this noise better? High or low frequency? High or low volume? Something may really have broken or failed, or this is inherent to the original design. So far, I can't say which it might be.
I opened the bottom of this tall speaker to look inside. It isn't easy to get to the guts of this speaker but what I could see inside made me pause. I saw cheap, zip cord type wiring running from the crossover to the back of the speakers. The connection to the individual speakers (there are approx 6 drivers in each enclosure) was also shoddy.
The existence of “cheap zip cord type wiring” inside an expensive speaker should reveal something important to you. Although many speaker manufacturers pay lip service to customer use of expensive or boutique speaker cables outside the cabinet, they ignore that inside the cabinet. Ignore your audiophile instincts here. Copper zip cord of reasonable thickness (18 gauge is alright for short lengths) is all that is required. Shielded wires are unnecessary. Resist the urge to “upgrade” the internal wiring. If It Ain’t Broke, Don’t Fix It.

Those connections between the wires and individual drivers may also look shoddy to you, but if they have survived 20 years, how bad can they be? Again… If It Ain’t Broke, Don’t Fix It.
The speaker units themselves also looked like Radio Shack cheepo models, the type you'd see inside the door panel of a given factory car system. Small magnets on the back of each driver, even the woofers! These speakers were not inexpensive. At the time they were selling for $6,600/pair. I'm thankful I didn't pay that amount.
The article linked at the top of this thread did talk about the advantages of drivers with cast instead of stamped metal baskets. However, it was meant as a shopping guide for people buying new speakers. While it is true that cast metal baskets are a sign of better quality drivers, it isn’t true that drivers with stamped metal baskets can’t also sound good. The same is true for the magnet size.

In your case, you already own speakers that I think you like. Mirage selected the original drivers and designed the cabinet and the crossover for them. If you replace the original drivers, you might as well get all new speakers because the cabinets and crossovers will have to change as well. You may not approve how your speakers look on the inside, but you do seem to like how they sound.

Yet again… If It Ain’t Broke, Don’t Fix It. I hope by now, you are seeing a pattern here.
There is a Linkwitz-Reilly crossover inside that appears to be passive (no power). I'm not a speaker designer, just an audiophile. BTW, the Linkwitz-Reilly guys are still in the business of designing x-overs.
Linkwitz-Riley is a type of crossover filter design that can provide better frequency response across the crossover frequencies than other designs. It isn’t a crossover manufacturer. In your speakers, Mirage probably designed and built the second order L-R crossovers.
… [this] article helped me to understand that [what I described above] might be a difficult job locating the right speakers for the design of this monitor and then combining them to sound right using the speaker's stock range considering the science you described. I knew going in it wasn't going to be a simple R&R, but now I'm having second thoughts.
Now you are making good sense :). Give Mirage some credit for designing what seems to be a good speaker. Many other people besides you have imagined they can “upgrade” their speakers by rewiring them or buying different drivers or crossovers and simply dropping them in place. While speaker design isn’t quite rocket science, it isn’t as simple as child’s play either.
 
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L

Lvnsnfnatk

Audiophyte
My general advice to you is If It Ain’t Broke, Don’t Fix It. Leave the individual drivers, the internal wiring, and the crossovers as they were built. If something is wrong, it should be identified as much as possible, and repaired. Otherwise, listen to your speakers. Don’t judge their sound by looking at them – especially inside.
If you hear “something wrong” only on certain pieces of music and at a certain volume level, it probably isn’t a bad voice coil. Can you describe this noise better? High or low frequency? High or low volume? Something may really have broken or failed, or this is inherent to the original design. So far, I can't say which it might be.
The existence of “cheap zip cord type wiring” inside an expensive speaker should reveal something important to you. Although many speaker manufacturers pay lip service to customer use of expensive or boutique speaker cables outside the cabinet, they ignore that inside the cabinet. Ignore your audiophile instincts here. Copper zip cord of reasonable thickness (18 gauge is alright for short lengths) is all that is required. Shielded wires are unnecessary. Resist the urge to “upgrade” the internal wiring. If It Ain’t Broke, Don’t Fix It.

Those connections between the wires and individual drivers may also look shoddy to you, but if they have survived 20 years, how bad can they be? Again… If It Ain’t Broke, Don’t Fix It.
The article linked at the top of this thread did talk about the advantages of drivers with cast instead of stamped metal baskets. However, it was meant as a shopping guide for people buying new speakers. While it is true that cast metal baskets are a sign of better quality drivers, it isn’t true that drivers with stamped metal baskets can’t also sound good. The same is true for the magnet size.

In your case, you already own speakers that I think you like. Mirage selected the original drivers and designed the cabinet and the crossover for them. If you replace the original drivers, you might as well get all new speakers because the cabinets and crossovers will have to change as well. You may not approve how your speakers look on the inside, but you do seem to like how they sound.

Yet again… If It Ain’t Broke, Don’t Fix It. I hope by now, you are seeing a pattern here.

Linkwitz-Riley is a type of crossover filter design that can provide better frequency response across the crossover frequencies than other designs. It isn’t a crossover manufacturer. In your speakers, Mirage probably designed and built the second order L-R crossovers.
Now you are making good sense :). Give Mirage some credit for designing what seems to be a good speaker. Many other people besides you have imagined they can “upgrade” their speakers by rewiring them or buying different drivers or crossovers and simply dropping them in place. While speaker design isn’t quite rocket science, it isn’t as simple as child’s play either.
Thanks for getting back to me so quickly!

My Levinson No. 37 just expired last month (@18 yrs old) after I had written this post, and I was without music until this week.

**On the advice of some audiophiles, I picked up an Emotiva ERC-3 Cd player. It's breaking in.

I'm going to leave the Mirage's alone for the time being. Thanks for the time worn advice! I forgot to mention that my Levinson No. 336 had its crappy Phillips/Chemicon capacitors replaced 2x in the past. The amp is probably 15 years old. Knowing the amp displayed a similar buzzing in my Mirages before, I suspect it might be the culprit instead of my speakers. I just got the Emotiva running so i'm going to listen for the issues that my tinnitus-ridden ears originally picked up.

For the record, I got the idea to rebuild my speakers from a guy named Gary Reber who was editor for a magazine called, "Widescreen Review." He replaced his internal wiring on his M1Si's with Monster cabling and seemed to like the results. Not sure if that mag is still out there.

I was once an audiophile fanatic. I'd guess due to my personality traits, the quest for music perfection was emptying my bank account faster than I could refill it. I feel the need to tweak most things I obtain including my exterior home remodel that I finished last year (i'm a carpenter). I'm rarely satisfied with anything but when it came to Levinson and Mirage, I stayed with them for all these years and still love their sound. The Emotiva is the first non-Levinson product i've purchased in 13 years beside the Ref Chang Lightspeed, which I no longer use.

Speaking of the 336, Cornell Dubilier makes a killer 50kuF/125v capacitor that is better than the original Chinese caps in my Levinson. The original caps caused problems/noise that I could hear in my Mirages (shipping the amp was a bear). I'm gonna look into replacing what I suspect is the problem and along the way, my amp will sound better than it did when new.
 
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