Goal: Create a center channel speaker that compliments/matches my ESS AMT-1D main spe

[Actinade]

Please help me! I am serious and want to build my own center channel. I have wanted to do this for years and realize that there will not be what I want created - I have to create it. 😀

Goal: Create a center channel speaker that compliments/matches my ESS AMT-1D main speakers. 😱

Question: does my goal make practical sense? Can I do it?
Question: if so, I can use 1 or 2 AMT tweeter and I would guess that I would have 1 or 2 woofers added to make the center channel speaker. What woofer should I use? If I wanted only 1 woofer could I use a Fostex speaker in a sealed box? (please see attached images)

First of all, I have never tried to make any home HIFI components so please bear with me as I learn

the terminology, etc. The most I have done is to make out of MDF some basic sealed boxes for automotive apps 🙂 I am a bit

better with circuit layout and implementation etc. but my knowledge is most definitely not current and lacking for AC stuff.

I know that I over spec things but I try to make complete SOW for work projects so now I am compelled

to give information overload, so I will separate this into two posts! This one is the high level with pictures 🙂

The 2nd post will have more excruciating details!!!!!!!~

Here is a mockup of style MTM with the HEIL in the middle and 2x4" or maybe 5" speakers are inline horizontally... I understand that the 2 mid speakers could cancel out each other some, so...

This mockup is showing TMT config, is there a reason that this would be very very wrong? I just dont see this config anywhere... the 'M' would have to be a nice little driver to handle all the chores of mid voice/center channel info from movies, etc. Cost would be something to look at vhere the HEILs sell for $400 a pop without xovers, etc but I think I could just buy another set of AMT-1 series speakers in bad shape and grab the HEIL's and their xover systems?

This mockup is perhaps more ideal... but for one, I am unsure that it would fit in the space inbetween my AV rack and TV which is no more than 12"

What do you think? Please provide critical feedback and tell me where I am off!

😀😀😀😀😀​

Here are my current 3 front speaker config (AMT 1-D)
(I have raised up the AMT's and evened them since this photo)

 

[Actinade]

Goal: Create a center channel speaker that compliments/matches my ESS AMT-1D main speakers (post 2 details)

From my best understanding, this means matching the higher end characteristics of these ESS speakers, therefore I need to make a center channel around the GREAT HEIL / AMT (Tweeter)

From the ESS site:"The AMT ... range of 500 to 20,000 Hz. ...Crossover frequency is 800 Hz at 12db/octave or more. Impedance is 4 ohms nominal, 3.5 ohms minimum. Maximum sustained RMS power is 400 watts RMS band limited pink noise, 160 watts maximum peak. Sensitivity is 92db for 1Watt @ 1 Meter."

When I went to ESS and worked with Ricky to restore these speakers (I have bookshelf PS-820's as well)

Every cone and radiator, every surround were shot; Ricky recommended paper for the cones as he said paper is very light and therefore paper speaker cones has the best chance to try and keep up with the AMT's speed...


Therefore, my Desires:
1) fast speaker performance for the woofer
2) sealed box for the midrange-woofers
3) The Heil AMT(s) will be out in the free air as I will match the 1D's in how they fire front and back


Constraints:
1) The ESS 1D's are rated at 4ohms... So should the new center channel match this as well?
Specs on this speaker are included here
http://www.essspeakersusa.com/ESS_FINAL.pdf


2) Expected power I will have available for the center channel should be at least near 90 watts RMS


3) I do have an absolute maximum of 12" of height between my TV and my AV rack.
What I mean is that right at that 12" mark, it is physically touching the bezel of my plasma TV

3b) I am unsure what a heil would do close to my plasma anyway, BTW it is a Samsung 60F5300, I hear that unshielded speakers do not affect plasmas but I don't know this from 1st hand experience


In summary, HELP ME I DONT KNOW WHAT I'M DOING AT ALL - ONLY WHAT I HOPE TO MAKE! Where do I go from here? I got specs, desire and some finance... and a professional woodworking friend (he has not made speaker boxes before but he is really talented) please lend me your wisdom

 

[xrk971]

I made a 2-way with an AMT and a 5in sub driver W5-876SE (discontinued) but any 6.5in Peerless woofer would work. Use a sealed box and make it an WTW and XO at about 700Hz. That way the AMT handles the main telephone band for awesome vocal clarity and audibility. Don't do the TWT - you would get bad comb interference that way.

http://www.diyaudio.com/forums/full-range/265915-hyperfast-hypercube-based-2-way-11.html#post4156111

Here is the FR I got:

Impulse:

Minimum Phase:

This was just a quick prototype:

It sounds very nice and I think would make a great center channel.

 

[Actinade]

I made a 2-way with an AMT and a 5in sub driver W5-876SE (discontinued) but any 6.5in Peerless woofer would work. Use a sealed box and make it an WTW and XO at about 700Hz. That way the AMT handles the main telephone band for awesome vocal clarity and audibility. Don't do the TWT - you would get bad comb interference that way. ...

Thank you very much for the response. I see that the prototype is like my 3rd image/config. Is that how it ended up? Do you have a pic of the finished product 🙂
OK roger on the kabash of the TMT, however would I not also get some interference with MTM (just not as much?)

Oh yes - one more question: did you have to add a potentiometer or something to adjust the sound/loudness between the AMT and the woofer? Thanks again!

 

[xrk971]

I never went with a final build because I used the AMT for another project. But I can see how I would have really enjoyed it simply as a two way in a top/bottom type box. It has wide dispersion so you don't want to block its sides. I used biamp with TPA3116D2 amp and miniDSP so I could easily dial in the relative balance. The AMT is very sensitive to you need a sensitive woofer or two if you want to keep up with it.

 

[Actinade]

you have nailed down my question

Thank you again. You have really nailed down my question:

-I do wish to employ a sealed box for the woofer
-I also think that I need a speedy/sensitive woofer (how do I find selection criteria? How would I fine likely candidates?)

-How would I dial in the 'relative balance' between the woofer and the heil/amt if I am running off a standard center channel output?

-Finally would the old rule of thumb to make a sealed box in proportions of 0.6:1:1.62 still hold true for this application

Thanks for your help!!!

 

[Finnogangela]

2 articles might be of help:

Vertical vs Horizontal Center Speaker Designs | Audioholics

https://www.yumpu.com/en/document/v...-in-practise-dapolitto-duelund-coherent-audio

 

[xrk971]

Thank you again. You have really nailed down my question:

-I do wish to employ a sealed box for the woofer

Sealed gives best transient response​

-I also think that I need a speedy/sensitive woofer (how do I find selection criteria? How would I fine likely candidates?)

High sensitivity, large xmax, higher Qts for hitting lower 80Hz with sealed box, look for fs well below 80Hz - say 50Hz fs, Qts of at least 0.5, and at least 6mm of xmax.​

A good esxample is this driver Peerless SDS-160F25PR01-08 6-1/2" Paper Cone Woofer Speaker​

-How would I dial in the 'relative balance' between the woofer and the heil/amt if I am running off a standard center channel output?

You need a 700Hz XO which is not easy to come by with passive components. You need a XO and an L-pad (variable resistor) to adjust the balance. If you go with a higher XO, you are throwing away the special and unique ability of the Heil AMT to cover from 700Hz up to 20kHz for a truly special sounding phase coherent speaker.​

-Finally would the old rule of thumb to make a sealed box in proportions of 0.6:1:1.62 still hold true for this application

I think you are talking about golden ratio boxes to avoid standing waves - don't worry about as you will be using quite a bit of stuffing​

 

[Actinade]

Thank you so much for your help and expertise... I am appriciative that your experiance is giving me a shortcut on what to look for...
I spent a few hours lookin online for a passive crossover 12 or 18 db/octave @ 700 Hz, could not find, not to mention a L pad or variable resistor to control the sound... not sure where to go now...
Here is one of my AMT-1D crossover network that had melted.. when I got them all battered from my buddy

But I did finally find a speaker in the configuration that I actually want to make AND get this: they did intent its use for a center channel!
B&W Nautilus HTM2 (well I dont want bass reflex I want acoustic suspension but it is close)

As far as controlling something with an adjustable resistor I remembered my use of a Variac, a variable potentiometer that could handle decent current I used this to help built a photo resist dipper for our thin-film lab, we used the Variac pot to control the speed of the motor in turn controlling the removal of a substrate from photo-resist... lol maybe *MAYBE* overkill for this application but I am stumped on what do actually do

I will just keep plugging away. After I get a plan and find parts I will have the spec on the cabinet and where what electronics will be mounted as far as x-over and balance control. Therefore before I can do anything I must discover a speaker as the #1 first thing then the means to control said speaker!

 

[xrk971]

I can't help you with passive XO solution as I only know how to do active miniDSP bi-amp. It will cost you between $150 to $170 depending on what amp you get but will be competitively priced with the expenses of a passive XO that can handle 700Hz, and it is infinitely reusable for other projects.

Here is what I did:

You may want to look at pro-audio high sensitivity mid drivers that will cover you from 100Hz up the 700Hz XO in order to get the high sensitivity needed to match the Heil AMT. For example:
PRV Audio 6MB250-NDY Neodymium 6-1/2" Midbass Woofer 8 Ohm

 

[Actinade]

Thank you I will look into that, meanwhile late last night I found some items of possible interest...?

Would this work for a x-over for the Heil? Is it good enough or should I try to build my own out of componentry?
XO3W-700/5.6K 3-Way Crossover 700/5,600 Hz
DAYTON AUDIO

Dayton Audio XO3W-700/5.6K 3-Way Crossover 700/5,600 Hz

Or there is this:
3-Way Crossover Network - 12db/Octave 700hz/3khz 60w Rms
by MCM
Amazon.com: 3-Way Crossover Network - 12db/Octave 700hz/3khz 60w Rms: Electronics


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Maybe Instead of an L-Pad
Fostex R100T Transformer Type Attenuator

Amazon.com: Fostex R100T Attenuator: Electronics

http://www.fostexspeaker.de/accessories/att.pdf

Well, actually every L-Pad and this Attenuator as well cite 8Ω whereas the Heil and the speakers I am looking at are are 4Ω

 

[Actinade]

Thanks again ... however I think I will go for this project, but I want to start with a
T
M
configuration (like yours) but I am space constrained to 12" total
the heil is 6 3/8" tall
meaning that 4.5" woofer is on the outsize
4" is more like it... so I am on the lookout for a 4" that fits your criteria if i can 😀