Why do my 288-8Ks sound like cr@p?

I just ordered two new GPA diaphragms.

They were a bit hesitant to sell them to me, assuming I did not like the 288 character. Kudos to that attitude, wich I think is a good customer relation is all about!
In hindsight I think reports on people not liking the 288-k has more to with faulty diaphragms than with an alnico or a circumferential-slotted phaseplug preference. Those will matter in the end, but are in the realm of "288-k ok, good but not my thing" rather than "dude switch off immediately".

Which brings me to an offer to you. i will off course measure again with the new dias but I wondered is there anyone who would like to measure my distortion makers in their units?

There is off course a tiny risk that the new dias don't work out and the cause is elsewere....

Coen

I would, but I don't have the darn locater sleeves. Talked to GPA this afternoon and they said to center them with a 200Hz tone at 2V. That's how they do it. Sure wish I had the sleeves, it would be much faster and easier.

Coen,

I wish I had posted my thoughts before you ordered those diaphragms ( maybe it's not too late to get GPA to do the following ) .

Thought :

• Whether you agree ( or realize it ) , GPAs current pricing for a 288 diaphragm is a steal . So ;
• Offer them a $50.00 premium over the going rate ( for each diaphragm ) to test each for performance ( FR & Distortion, obviously ) / as well as matching specs to each other ( which is fairly critical for HiFi based listening, unless you are a whiz at creating passive EQ correction ) .
• This extra $100.00 is well spent towards avoiding the head-aches ( & nastiness ) of a getting a mediocre performing diaphragm, due to some liberal QC standards.
• This "Insurance Premium" would nicely address GPA's ( very real ) concerns about selling components to those of us who actually measure things for their expected performance traits ( & don't just readily accept the Kool-Aid of "How Great It Was In The Past" ) .

That was my main thought ( for the day ) that I wanted to share .



<> :)

I sure hope it works, But if it doesn't at least you'll know it's not the phrams.

Quote:

---

Originally Posted by Coendert2011

Nice work!

Those pics are unfortunately awefully small. Left of 1kHz is hi passed away?
Interesting peaks on 10 and 12kHz. So these could be related to the 802-g radial phase plug that is in our 288-ks as well....

Did you use any compensation for the bumps/nothces?

Coen

---

That was with 15uF capacitor. No compensation.

Here is 802 with hf compensation
Attachment 1346


BTW Why don't you try to align the diaphragms in those 288s?

Quote:

---

Originally Posted by Panomaniac

I would, but I don't have the darn locater sleeves. Talked to GPA this afternoon and they said to center them with a 200Hz tone at 2V. That's how they do it. Sure wish I had the sleeves, it would be much faster and easier.

---

That's acoustically unloaded? And what do they look for? I only have the replacement instruction using the spider shims for centering.

Gpa siad that the jigs/shims are supplied with the new phragms.

Coen

Quote:

---

Originally Posted by Earl K

Coen,

I wish I had posted my thoughts before you ordered those diaphragms ( maybe it's not too late to get GPA to do the following ) .

Thought :

• Whether you agree ( or realize it ) , GPAs current pricing for a 288 diaphragm is a steal . So ;
• Offer them a $50.00 premium over the going rate ( for each diaphragm ) to test each for performance ( FR & Distortion, obviously ) / as well as matching specs to each other ( which is fairly critical for HiFi based listening, unless you are a whiz at creating passive EQ correction ) .
• This extra $100.00 is well spent towards avoiding the head-aches ( & nastiness ) of a getting a mediocre performing diaphragm, due to some liberal QC standards.
• This "Insurance Premium" would nicely address GPA's ( very real ) concerns about selling components to those of us who actually measure things for their expected performance traits ( & don't just readily accept the Kool-Aid of "How Great It Was In The Past" ) .

That was my main thought ( for the day ) that I wanted to share .

<> :)

---

Thanks a lot cor the advice. I hardly crossed my mind that the new GPA dias could have the same problem. I was actually counting on a good reference. I have a pair of new small format gpa dias that are very close. Thats the one I measured I few posts back. Distortion is under the noise floor.

I followed your suggestions and asked for the testing/matching on a price premium. I hoped the units aren't shipped allready.

Coen

Quote:

---

Originally Posted by Coendert2011

That's acoustically unloaded? And what do they look for? I only have the replacement instruction using the spider shims for centering.

Gpa siad that the jigs/shims are supplied with the new phragms.

Coen

---

You can even do it by ear - listen for the cleanest tone - with the least amount of harmonics. Of course you can check it with ARTA - on the spectrum analizer look for the smallest amount of harmonics.

Quote:

---

Originally Posted by vuki

That was with 15uF capacitor. No compensation.

Here is 802 with hf compensation
Attachment 1346


BTW Why don't you try to align the diaphragms in those 288s?

---

Nice! So this is inclusiding the hi pas isn't it? You removed the bump with a low q notch filter?

Aligning is next on the list, need to find an appropriate method.

Coen

Quote:

---

Originally Posted by cradeldorf

I sure hope it works, But if it doesn't at least you'll know it's not the phrams.

---

If I can count on the quality of GPA....

Coen

Quote:

---

Originally Posted by Coendert2011

Nice! So this is inclusiding the hi pas isn't it? You removed the bump with a low q notch filter?

Aligning is next on the list, need to find an appropriate method.

Coen

---

No notch filter, just 12db/oct highpass + attenuation & hf compensation.

The easiest method would be to take off rear cover from the driver, slightly loose the screws that hold diaphragm (so much that it still sits firm, but that you can also move it by gentle tap with some heavier tool eg. screwdriver handle) attach 200-500hz sine tone signal to the driver and listen the tone. By gently taping the side of the diaphragm you'll be able to move and align or misalign it and you will hear the tone changes from clear/soft when aligned to sharp/dirty when misaligned. You can control it via ARTA spl function - just watch for the lowest amount of harmonics. When you find the best position slowly tighten the screws paying attention not to disturb aligment (by listening or measureing while tightening).
Driver doesn't have to be loaded to do it - so you can do it on the table. :)

Quote:

---

Originally Posted by Coen

I followed your suggestions and asked for the testing/matching on a price premium. I hoped the units aren't shipped allready.

Quote:

---

Originally Posted by cradeldorf

I sure hope it works, But if it doesn't at least you'll know it's not the phrams.

Quote:

---

Originally Posted by Coendert2011

If I can count on the quality of GPA....

Coen

---

---

---

I feel it's best to think of this request ( for matching & testing ) as a request to "blueprint" the diaphragms to original OEM spec.

That's a common term used in the world of engine re-builders and warrants a premium price point for the necessary extra work .

:)

Quote:

---

Originally Posted by Coendert2011

That's acoustically unloaded? And what do they look for?

---

I don't think unloaded, but I didn't ask. Listen for any buzzes or the cleanest tone. That's what they said. (I think I was talking to Bill). Use 3 screws just slightly snug then add the other 3.

Quote:

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I only have the replacement instruction using the spider shims for centering.

---

Yep. And to do that, you need the alignment sleeves, which I do not have. The paper shims come with the 'frams. If you don't have the alignment sleeves (or whatever they are called) then you can't hold the position of the diaphragm once it's removed to take the shim out.

Quote:

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Gpa siad that the jigs/shims are supplied with the new phragms.

---

Paper spider shims, yes. The driver is supposed to have the sleeves, mine did not.

------------------------------------------------------------------------------------------------------------------------------------------
"THE ALTEC USER BOARD" IS "PRO GPA" ! FOR A REASON ! THEY PRODUCE ORIGINAL ALTEC PARTS !
.

Quote:

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Originally Posted by Coendert2011

If I can count on the quality of GPA....

Coen

---

And you CAN ! I've been dealing with Bill/GPA for a longtime and have yet to have a problem.Oh wait a minute. I had one issue Bill forgot to add a few washers in a hardware kit I bought for some 288's,(Studs,nuts,washers,gaskets) so he sent me double for the mistake. :cool: GPA will stand behind any of their products.You won't find better for Altec parts or diaphragms anywhere else IMHO...

You seem to be doing a great job investigating the issue yourself !! Listen to your own opinion, it won't steer you in the wrong direction.

The best advice I can give you here is go with your instincts... Do your own investigation... It will be the best advice for your application !! Graphs will only get you so far (For Building Crossovers & Enclosures).In the end it is how it sounds to you that is important. :smile2:

@Vuki,

Thanks for the instruction. I guess GPA is driving the driver into serious distortion anyhow with 200Hz @2V unloaded. I am curious to the experience of moving the diaphragm around and hearing the distortion vary.

@Pano:

You are referring to the 'adjustable Dowel Locating Pins' wich can move a little to center the phragm and be clamped afterwards by a screw. Won't GPA be kind enough to deliver a pair of those for you to get the job done right for once and for all?

So I take it you have a set of permanently misaligned 288s. I saw no distortionlines in your measurementgraph with the 1005 horn (post 48). Does thie misalignment result in bad sound or in "could be better" sound.


@Altec Best

My experience so far has been excellent too. Your confidence is reassuring!

Coen

If you ask GPA for the Dowel locating pins, they may be able to send some. They did not come with my GPA frams as they are supposed to be with the driver. Apparently, they tend to stick in the fram surround and get thrown away at change out time. That most have happened to mine before I got the drivers.

Although it's supposed to be easy to align by ear, I had a devil of a time with it. Sure wish I had the dowels. Maybe you have more finesse than I and will have no trouble.

http://www.hostboard.com/forums/atta...p-288-1005.png

Below are Pano(s) distortion sweeps from a couple of years back for one of his ill-fitted 288 diaphragms from GPA ( one can see from the first pic [which is more recent] that he has achieved a somewhat better fitup compared to a couple of years back ) .

http://www.diyaudio.com/forums/attac...fram_steps.png

Above was made with STEPS , while below was made with HolmImpulse .
.

http://www.diyaudio.com/forums/attac...8-bad_holm.png

vs his 291 diaphragm .

http://www.diyaudio.com/forums/attac...distortion.png

http://www.diyaudio.com/forums/attac...e-backside.jpg

<> :)

Thanks Earl, I could not find that 291 measurement file. At least you've found the chart! I see that the symbiotic also has the 8.3K hole.

Earl,

For some rason I only see the top graph in Chrome and none of the graphs in Explorer.
Does anyone know what setting to change?

Coen

Quote:

---

Originally Posted by Coen

For some rason I only see the top graph in Chrome and none of the graphs in Explorer.

---

Quote:

---

Originally Posted by Coen

Does anyone know what setting to change?

---

The bottom 4 pics are hosted over at diyAudio . I'm now thinking that one needs to be registered there to see them .

3 are .png files while the other is a .jpg / so I doubt it's a browser setting .

:)

PS : The simplest solution ( I guess ) is to simply register at diyAudio ( unless Pano wants to retrieve the pics & then host them somewhere that will retain their original size ) .

@ Earl, I will logon DIYaudio to get the cookie.

Just a little note from the centering activity of tonight.

The 288-Ks don't have the dowel pins. There are the two little bolts that have an oversized washer around them that is part of the diaphragm. I think the adea is to get audibly rid of the nasty resonance caused by the scraping of the voicecoil against the sides of the gap and then fix um.

I had a little rattle on one unit (the measured one) and the other is 'totally' clean. 200Hz at 2V works fine, you have a lot of movement in the diaphragm and any misalignment is easily observed (heard).
It was a hell of a job to get rid of the rattle, there is only one position that the rattle disappears (almost). I have the impression that the gap isn't evenly distributed, iow the phaseplug isn't totally in the centre. I have to measure to be shure.

Sorry no measurements yet of the recentered unit with the horn in place, next week more results in this theatre.

At last, I checked the other 802 and it exibited a higher distortion. After a lot of searching it turned out that the metal strips on the diaphragm (where the Voice Coil is soldered to) stuck out a little. I carfeully scraped the excess away with a watchmakers tool. Putting it back it didn't work out completely satisfactory. A definite improvement yet I discovered that I had to play with the pressure on the fixing screws to make distortion disappear. Thia was also the case with the better diaphragm of the other unit when inserted this one, so this is an imperfection of the unit itself (I should check the gap here too!).

A very instructive night!

Coen

Good work Coen! Waiting for the new graphs :)

When you go Back to the 288's.You should really try fixing/replacing the locating dowel pins on those 288-8K's.As Pano & GM have said you need those to center the diaphragm easily and in a timely fashion.Once you have the pins you will make quick work of it before it drives you crazy or just takes too much of your time.. My point is it can become tedious.. :wink2: But your doing a great job ! Keep up the great work Coen.

Fitting old drill bits in the holes and then cutting them to size is a great idea as GM posted.If not GPA should be able to provide them for you. :smile2:

Quote:

---

Originally Posted by jOHN

Back to the 288's.You should really work on fixing the locating dowel pins on those 288-8K's.As Pano & GM have said you need those to center the diaphragm easily and in a timely fashion.Once you have the pins you will make quick work of it before it drives you crazy or just takes too much of your time.. My point is it can become tedious.. :wink2: But your doing a great job ! Keep up the great work Coen.

Fitting old drill bits in the holes and then cutting them to size is a great idea as GM posted.If not GPA should be able to provide them for you.:smile2:

---

Sheesh AB,

The newer series 288s include a 2-piece dowel system ( which includes a hollow over-sized sleeve & a small bolt that holds that sleeve in place ) .

It is not, a solid metal pin that can be simply replaced by a small piece of metal rod ( cut to length and stuck in the threaded hole as you & GM suggest ) .

BTW, Pano is missing the 2 over-sized sleeves that are snugged-up inside the 2 locator holes within the diaphragm & held there by the set-screw . ( Look at the picture I posted of Panos open-backed driver to see the set-screws ) .

The center "hole" in the sleeve is larger than the diameter of set-screw, essentially allowing the sleeve to "float" or slop around a bit ( when the set-screw is loose ). This "play" when used in conjunction with the spider shim is what allows for an accurate fitup in the new system .

http://www.hostboard.com/forums/hbmc.../2012/06/1.png


Coen's description of what he has seen in his 288s suggests he might have a fully functional ( adjustable dowel ) system ( compare to the pic above ) .

He simply needs to read the instructions on how to use it ( along with the included spider shims coming from GPA ) .

DownLoad & Read ;Altec Lg-Format Driver Diaphragm Replacement Instructions

:)

Quote:

---

Originally Posted by Earl K

It is not, a solid metal pin that can be simply replaced by a small piece of metal rod ( cut to length and stuck in the threaded hole as you & GM suggest ) .

---

Just to be clear, I was responding solely to Pano's post and did not say nor imply cutting the drill bits to suit [though of course one can do so when appropriate if they have the means to cut such a hard material!], but merely to use them to quickly align the VC for fine tuning as I've found that while the positioning may be geometrically correct, it isn't necessarily the best performing location IME with small format drivers.

Note too that my Altec large format driver 'hands on' experience is limited to just the 288B and even that was at a time when I assumed that the factory assembly was already 'optimized', so in retrospect shouldn't have posted on this thread and have deleted my misleading post.

GM

Thank-you GM ! for deleting your misleading post ( now maybe AB will follow suit ) .

:)

Since Coen is going to use drivers for home listening, once he determines and fixes position of the diaphragms, the drivers will be good for the next few decades. So, adjustable dowels, although nice and convenient detail, are not indispensable in this case.

Quote:

---

Originally Posted by Earl K

Sheesh AB,

---

Quote:

---

If not GPA should be able to provide them for you

---

Are you kidding ? I was only talking as a temporary means to align the diaphragm while he is tighten the diaphragm screws to help keep the diaphragm centered and from shifting.My advice as you know is to always Contact GPA first for obvious missing parts.! As I will always recommend buying original replacement Altec parts first... Bill/GPA I'm sure probably has these laying around. At the end of my post I said to call GPA for the missing pins...


BTW - As I previously posted I think Coen is doing pretty darn well himself IMHO ! Keep up the Good Work Coen ! Just keep measuring everything you can,practice will make perfect.I'm pretty sure you have a good handle on things. :wink2:

Quote:

---

Originally Posted by Coendert2011

I have the impression that the gap isn't evenly distributed, iow the phaseplug isn't totally in the centre. I have to measure to be shure.

---

On mine, it was the result of an impact, and the site was clearly externally noticable.
Of course, if it impacted the cover, the cover could be switched around, but only in so many possible orientations.

But of course maybe there are other reasons, pole pieces shift? idk.

* Ahh - and editing. I see you mention the phase plug specifically. I am sure we have seen mention of them coming loose/regluing in other posts, but I have not experienced this myself.

Quote:

---

Originally Posted by Altec Best

Bill/GPA I'm sure probably has these laying around. At the end of my post I said to call GPA for the missing pins..

---

Well they were hesitant to send me some, so suggested I try the 200Hz tone. If that didn't work, I think they'll see some. I'd be happy to buy a set and pay all postage, so I'll let GPA know that. I really don't know if they have a bunch of them hanging around. I think they were afraid of charging me too much postage for a few little pins. :)

Quote:

---

Originally Posted by Earl K

Sheesh AB,

The newer series 288s include a 2-piece dowel system ( which includes a hollow over-sized sleeve & a small bolt that holds that sleeve in place ) .

It is not, a solid metal pin that can be simply replaced by a small piece of metal rod ( cut to length and stuck in the threaded hole as you & GM suggest ) .

BTW, Pano is missing the 2 over-sized sleeves that are snugged-up inside the 2 locator holes within the diaphragm & held there by the set-screw . ( Look at the picture I posted of Panos open-backed driver to see the set-screws ) .

The center "hole" in the sleeve is larger than the diameter of set-screw, essentially allowing the sleeve to "float" or slop around a bit ( when the set-screw is loose ). This "play" when used in conjunction with the spider shim is what allows for an accurate fitup in the new system .

http://www.hostboard.com/forums/hbmc.../2012/06/1.png


Coen's description of what he has seen in his 288s suggests he might have a fully functional ( adjustable dowel ) system ( compare to the pic above ) .

He simply needs to read the instructions on how to use it ( along with the included spider shims coming from GPA ) .

DownLoad & Read ;Altec Lg-Format Driver Diaphragm Replacement Instructions

:)

---

I'm a bit shocked that Earl had to post this as i thought it was fairly common knowledge here.

I've never seen it, Never knew there was such a thing as adjustable locating pins. It does make great sense to do it that way.

Quote:

---

Originally Posted by Panomaniac

Well they were hesitant to send me some, so suggested I try the 200Hz tone. If that didn't work, I think they'll see some. I'd be happy to buy a set and pay all postage, so I'll let GPA know that. I really don't know if they have a bunch of them hanging around. I think they were afraid of charging me too much postage for a few little pins. :)

---

I don't know why they would be hesitant to sell them to you.It makes it much harder to align them without them.Agree with the last part probable don't want to charge you too much.Just ask for a dozen make it worthwhile.

Quote:

---

Originally Posted by bowtie427ss

I'm a bit shocked that Earl had to post this as i thought it was fairly common knowledge here.

---

And it is !!! When you don't have them in front of you it is easy to make a mistake..

I'm glad you guys zero'd in on the alignmentof the VC in the gap.
When I swapped the OEM frams out of my 904 duplex (symbiotic) to new GPA frams, the speaks just sounded bad. So I set up my spectrum analyzer with tracking gen and a mike and looked at the response. Huge suckouts. I put the original frams back in and they were gone. So just because this later model uses the od of the fram assembly to center, I tried loosenig the screws and guess what, suckouts gone! These speakers actually had a thin gasket between the fram and the hf driver body. Anyway, I ended up moving the fram around a bit and found the sweet spot and simply tightened the screws just enough to keep it that way.
It about drives you nuts listening to the thing sweep, but the results were worthwhile.
I am fortunate to have the test setup. a Tek 7L5 Sa withtracking Generator option. My mike is simply a Radio shack SLM with an output that feeds the SA. Not accurate for sure, but for this it worked perfectly.

Ron

Quote:

---

Originally Posted by RonSSS

I'm glad you guys zero'd in on the alignmentof the VC in the gap.
When I swapped the OEM frams out of my 904 duplex (symbiotic) to new GPA frams, the speaks just sounded bad. So I set up my spectrum analyzer with tracking gen and a mike and looked at the response. Huge suckouts. I put the original frams back in and they were gone. So just because this later model uses the od of the fram assembly to center, I tried loosenig the screws and guess what, suckouts gone! These speakers actually had a thin gasket between the fram and the hf driver body. Anyway, I ended up moving the fram around a bit and found the sweet spot and simply tightened the screws just enough to keep it that way.
It about drives you nuts listening to the thing sweep, but the results were worthwhile.
I am fortunate to have the test setup. a Tek 7L5 Sa withtracking Generator option. My mike is simply a Radio shack SLM with an output that feeds the SA. Not accurate for sure, but for this it worked perfectly.

Ron

---

Hi Ronn,

This matches exactly my findings. For the small formats and 604's don't tighten the new GPAs!

Coen

[EDIT]

The first unit had the most problems with getting centered. As you may observe the other unit does not have the remnant H2 distortion arount 1KHz, but has a higher H3 distortion:

Right unit:
http://www.hostboard.com/forums/hbmc.../2012/06/2.png

Left Unit (better):
http://www.hostboard.com/forums/hbmc.../2012/06/3.png

Peaks and valleys are also due to the location of the microphone and reflections within the horn. I can see some move and disappear when I move the mic.

Hi All,

Here are some fresh results!

I've done a FR STEPS measurement on both 'aligned' 288-8K drivers. Unit1 is the one that has been the mother of all previous 288 graphs.

Unit1:
http://www.hostboard.com/forums/hbmc.../2012/06/4.png

Unit2:
http://www.hostboard.com/forums/hbmc.../2012/06/5.png

Looks much better now, with some rising distortion after 3kHz (mass loading?!). No Gremlins in here anymore.

Though the units match quite good on FR, distortion is similar with odd peaks on unit1:

Unit1:
http://www.hostboard.com/forums/hbmc.../2012/06/6.png

Unit2:
http://www.hostboard.com/forums/hbmc.../2012/06/7.png


Not much goin on here. Unfortunately :Sad no:.

I dug a little deeper. See the next post:

Coen

Ok,

Here's some more.

I have another hunch that the harshness may have to do with the 12k peak. For this purpose I made seperate FFTs of a 12.5kHz sine and ones with both a 12.5kHz and a 2kHz tone.

Unit1 @12.5kHz:
http://www.hostboard.com/forums/hbmc.../2012/06/8.png

The above gives rise to some elbrows. There is actually a new peak at 1/2 the fundamental, that is also echoed at the other side of the 12.5kHz. This one is not there in unit2, so is not related to the sound of -both- units. This must be some side effect of my imperfected centering capabilities.

Unit2:
http://www.hostboard.com/forums/hbmc.../2012/06/9.png

In the dual tone test this doesn't show up, I think because both tones are much lower in amplitude individually.

Unit1:
http://www.hostboard.com/forums/hbmc...2012/06/10.png

Unit2:
http://www.hostboard.com/forums/hbmc...2012/06/11.png

No real surprises here I'd say. With a lot of midrange in the music I can get a little crowded around the 12.5Khz though...

Well, I'm still waiting for the new GPA diaphragms. In the meanwhile I will do an impedance measurement. I might be that the highish output impedance of my favourite tube amps doesn't match well with the impedance peak likely to be associated with the 12.5KHz peak (amps increase output with rising impedance). Favourable for LF response, yet with an allready firm 12kHz bump, it can be too much on the HF.

Thanks all for the support. The story continues...

Coen

Coen, the 12kHz bump is what you get with the 288's - that's normal. The bump goes away off-axis, so the power response is usually quite smooth. I think that the response of your realigned 288's is very acceptable. I suspect that GPA diaphragms won't bring anything much better.

288-8k on Lecleach 450Hz horn
Attachment 1368

same with hf correction
Attachment 1369

at 30 deg off-axis
Attachment 1370

Quote:

---

Originally Posted by vuki

Coen, the 12kHz bump is what you get with the 288's - that's normal. The bump goes away off-axis, so the power response is usually quite smooth. I think that the response of your realigned 288's is very acceptable. I suspect that GPA diaphragms won't bring anything much better.

---

Hi Vuki, maybe I was a little overconfident that the new diaphragms would cure the harshness and a little too fast in ordering for shure. Well they are paid for and on the road so let's wait and see for the final verdict.
Anyhow, even if these do not make the desired difference I really would like to proceed to get to the bottom of this and make them sing in my setup. Your off axis graph for instance makes a lot if sense to me.

I noticed the 12k bump in the other 288-k graphs before. Save for what the diaphragms may bring this is suspect nr 1 next on the list. Furthermore I'm interested in your opinion on the 288-8k, do you like them all theway up, or do you consider a seperate (super) tweeter like gm suggested?

Coen

I'm using them without supertweeter. They sound (to my ears) better than 902s on 511 or even tractrix. BTW those were GPA dias in the 288k's that were measured.
I suggest you to measure 902 on 511 with the crossover than the 288, keeping the exactly same measuring conditions (distance, mic placement, amp gain etc). Using ARTA's overlay function you'll probably find out more about sound difference between those drivers.