ML sub specs

Hi all. I have reviewed the specs in the lit. and pdf manuals.

I see reference to excurtion but no specs.

I don't suppose anyone of you knows what the xmax or maximum excursion is for the 8" woofers in the Depth and Depth i, and the 10" woofers in the Descent and Descent i, do you?

Also what is potentially, the total volume of air displaced by these by the 10's and the 8's when they are going through their max excursion?

Or do I need to contact ML to get this info.

Thanks

Bruce

Maybe a test would satisfied your curiosity.

http://www.avtalk.co.uk/forum/index.php?t=msg&th=18352&start=0&rid=14&SQ=1147288566

Specs - and peak to peak excursion

Daniel,

Thank you. :rocker: This is first real world test results I have seen. I need to examine them in more detail.

Did I miss it or did they not include data on peak to peak travel on the woofers?

Thanks again for a great reference.

Bruce

NO Xmax specs

OK. No one stepped up and provided the specs.

I emailed ML tonight. We will see what they have to say.

All the above is probably moot. I pulled the trigger!

I will have a Behringer DSP1124P tomorrow. And........

My two new Depths should be here Monday or Tuesday!

This is exciting!

Unpublished information

OK. I took the bull by the horns, and got trampled.

I email ML with my question about xmax on the Depth.

After a few days with no reply I called ML.

I spoke to a very pleasant gentleman who did not know the answer, but put me on hold to go get the answer.

When he returned he said he had spoken with an engineer and the answer was "That information is unpublished." The engineer would not give the info to Brian. I guess for fear that he might tell me.

So, I guess I have my answer. Xmax is unpubished and not for public consumption.

I suppose a close estimate could be calculated based on the the air volume moved, that is quoted in some of test reports.

ML responds

Brian told me if there was an email floating around ML they would find it and respond.

They did and maintained the party line.

Hi Mr. Weiland,

I apologize for the delayed response, but thank you for your inquiry regarding Martin Logan Products. The delay in responding to your question was due to the fact that we do not have the excursion information on the depth subwoofer published. Because it is not published, after consulting our engineers and product development team, they are not at liberty to divulge this information. They hesitated to publish this information as physical and mechanical excursion varies, and we pride ourselves on real world application with no “marketing mark up.”

I apologize again for the inconvenience, but if there is any other specific information I can assist you with we would love to do so in a promptly manner. We do feel very strongly that the combination of your Prodigy with a Depth subwoofer would be a great combination. If we can be of any further assistance at all please don’t hesitate. Thank you very much for your passion and dedication to Martin Logan.

Sincerely,

Jake Mooney


I haven't been able to find the test report that I ran across that gave the max amount of air volume moved.

Why is this such a significant specification for you? I'm not trying to be a smartass, I really want to know. An earlier response gave a detailed series of graphed test results of response, harmonics, etc. Other than potential maximum volume, the air moved and/or driver excursion seems less significant in comparison to response rates, THD, tracking, etc. For good or ill, Martin Logan has historically always refused to give additional specifications beyond those shown in their marketing materials. Members here have previously sought impedance graphs and other data. ML generally politely declines. I find it somewhat refreshing to find an audio company that is not trying to sell their products through specsmanship. They prefer that you listen and decide for yourself.

FWIW, I have two Depths and like them alot. My room doesn't warrant a Descent - probably not even two Depths - I just wanted to get the second Depth since they had been replaced by the "i" series which I don't particularly like the looks of. The fact that they were deeply discounted after being discontinued didn't hurt either.

SteveInNC said:

Why is this such a significant specification for you? I'm not trying to be a smartass, I really want to know. An earlier response gave a detailed series of graphed test results of response, harmonics, etc. Other than potential maximum volume, the air moved and/or driver excursion seems less significant in comparison to response rates, THD, tracking, etc. For good or ill, Martin Logan has historically always refused to give additional specifications beyond those shown in their marketing materials. Members here have previously sought impedance graphs and other data. ML generally politely declines. I find it somewhat refreshing to find an audio company that is not trying to sell their products through specsmanship. They prefer that you listen and decide for yourself.

FWIW, I have two Depths and like them alot. My room doesn't warrant a Descent - probably not even two Depths - I just wanted to get the second Depth since they had been replaced by the "i" series which I don't particularly like the looks of. The fact that they were deeply discounted after being discontinued didn't hurt either.

Click to expand...

Well, besides that there is a lot of information that as a manufacturer you simply don't want to disclose in general. We have a number of "Trade Secrets" in my business that if published would give our competition a better understanding of how our products function and perform. We would of course prefer to keep such things to ourselves. I am certain Martin Logan has similar reasons for not choosing to publish these types of specifications.

Why I "wanted" to know

Steve and Tim,

Firstly, I did not/don’t take offense to your questions. I, probably naively, thought that comparing xmax or what I was really after, total air volume moved, would give me a parameter that I could use to compare subs, to assist in my buying decision.

I suppose the frequency response against output and the dynamic compression graphs really tell me all I need to know. However, those test have not been done by the group who’s link was provided on all the subs I was considering.

Secondly, I certainly understand ML’s “published spec” stance. It was just the first time I have had a company give me that type of answer. I guess in the past I just haven’t asked about information that a company considered proprietary.

Thirdly, I was in no way trying to besmirch ML by “publishing” our interaction. I thought they handled it well. I was just letting others know what I found out about the requested spec.

Finally, as Steve pointed out, the Depth is deeply discounted. My two new Depths will be here Tuesday. I already have the Behringer DSP1124P to use with them.

Hey guys, thanks for the interest in the this thread. I hope this clears up any confusion.

Bruce

XMAX is calculated differently by different manufacturers as well. Some calculate linear BL Xmax while others use hard lock-up xmax. Being servo-controlled...the xmax isn't as important, since the servo's going to prevent you from ever really reaching it. You can reverse engineer the XMAX though using something like unibox, and looking at the rate at which the bass is rolling off at higher power levels.

XMAX will tell you a "little" bit, but it takes twice as much excursion to play 3db louder, so you either need multiple drivers, bigger drivers, or a different alignment to give yourself greater output...as any reasonable guess at the XMAX of the depth would likely give you just a very small change in the output characteristics. So, take a guess at around 20MM or so, and you should be in the ballpark.

The main advantages of the depth, imo, are the alignment, which causes mechanical distortion to cancel, and servo, which lowers distortion, and prevents overexcursion. Comparing the depth to something else that doesn't have that, would be like comparing cars based on horsepower alone...

I appreciate you posting all this...thought it was very informative...(and I think the other two were just giving advice/perspective as well.) It certainly does make sense they they wouldn't publish the specs...though you could test the drivers themselves similarly to how they're tested by zaph-audio...to find the true T/S parameters of the drivers.

IWalker said:

...though you could test the drivers themselves similarly to how they're tested by zaph-audio...to find the true T/S parameters of the drivers.

Click to expand...

Thanks for the Zaph reference. I hadn't been to this site before.

Now that I have made by purchasing decision I really don't care about xmax.

Now it is just about dialing in the bass in my room.

Again thans for the reference.

Bruce

Ther subs are here

They arrived Tuesday. I have had a little time to play with them.

I can tell I am going to be very pleased with the final result.

More than enough output and can go below 20 Hz before any drop off.

Beating a dead horse

OK, as you know I have a pair of Depths to go with my Prodigy. And I absolutely love them.

I have since had a very nice email discussion with Peter Soderberg, MartinLogan International Sales Mgr.

The speaker level/high level input makes a better match in my system than line level. Peter mentioned that ML's experience is that using the speaker level input tends to cause the internal amps to take on the characteristics of the "Main" amp, and therefore a better blending. Thus the current choice of high level input only, on the current top two models, for their internal amps.

Now to the dead horse;

As you also know I asked for an unpublished spec. (xmax). ML's position is that, that spec could be very misleading given the way other manufacturer use it.

As an example, the following website publishes the spec I was looking for, however it is for the older Descent.

http://www.listening.co.nz/index.asp?PageID=2145839495

“Each of Descent's 10-inch aluminum-cone drivers weighs 8 pounds and has a maximum peak-to-peak excursion of 1.2 inches. That works out to a total displacement of 30 cubic inches - typical for most high-quality subwoofers. Descent has three of these drivers, however, yielding the equivalent acoustic power of a 24-pound driver with a maximum peak-to-peak excursion of 3.6 inches and a total displacement of 90 cubic inches. Moreover, each of these drivers is individually servo controlled for absolute minimum distortion. The single-driver alternative would be an extraordinarily robust 18-inch unit, which by virtue of its size and very long excursion would inevitably generate considerably higher distortion. Descent enjoys all the advantages of the smaller, more refined drivers while achieving the output capability of a huge 18-inch driver.”

Using the above numbers this would make an effective radiating diameter of 9.77” from this 10” driver.

http://www.sunfire.com/TrueSubwooferEQPR.htm

Sunfire published specs for their number two sub (true subwoofer eq) which according to them has an 8” “bore” and a 2.35” stroke and moves 235 cu. inches of air!

{I am using these examples because Daniel referred me to this wonderful website that tested the Sunfire EQ and the Depth http://www.avtalk.co.uk/forum/index.php?t=msg&th=18352&start=0&rid=14&SQ=1147288566 )

My calculations put the active driver at about 118 cu. inch. so they must be getting another 117 from the passive radiator (assuming the same stroke) – at the frequencies at which they are in phase with each other.

So here comes the logic. According to Sunfire the True Subwoofer EQ moves 2.6 times more air, at max than the old Descent as listed on the website from New Zealand.

OK the Depth is in a 30% smaller cabinet than a Descent. Next the three 8” drivers have approximately 33% less driving area then the 3 – 10” drivers in the Depth. Therefore the Depth, given the same maximum “stroke” should move about 30% less air than the Descent or about 60 cu. inches.

That would mean that the Sunfire moves almost (3.91) four times the air as the Depth.

If one opens two browser windows and compares the graphs of the Sunfire to the Depth one will see that the Depth is equal to or out performs the Sunfire in almost ever test.

http://www.avtalk.co.uk/forum/index.php?t=msg&th=18352&start=0&rid=14&SQ=1147288566

http://www.avtalk.co.uk/forum/index.php?t=msg&th=22062&start=0&rid=14&SQ=1178745521

I guess that is why it is an unpublished spec for Martin Logan. It is one of those “All things being equal…..” and they never are.

Bruce

question

Bruce, you posted "Thus the current choice of high level input only, on the current top two models, for their internal amps." Last time I checked (about two minutes ago ;--) both the Depth and Descent manuals showed both speaker and line level inputs (and line level outputs) Or were you referring to their Summit and Vantage speakers?

clearing it up

nsgarch said:

...... Or were you referring to their Summit and Vantage speakers?

Click to expand...

Thanks for pointing out my potentially confusing post. Yes, I was referring to the Summit and Vantage.

ML has left multiple choices on the subs to allow one to best integrate them with one's main speakers.

Hey Bruce, it's nice to see another Koetsu owner on the forum!