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preliminary design for Allied 15" 615HC "Triaxial" drivers

doucanoe

doucanoe

Registered Audio Abuser
I've been messing around with a pair of Allied 615HC (EV 15TRX) drivers in the basement set-up. They are currently in the @ 4.5/5 cu-ft Barzilay cabs they came in.

The 615HC's were re-capped a week or so ago and am thinking that they might prove interesting in a larger but manageable BR cab around 8 cu-ft net internal after driver and bracing is subtracted.. I'm curious to hear other opinions regarding volume and box tuning for these drivers.

I haven't been able to locate any consistent parameters (Fs for example) for these relics. I'll be running them through WT to see what I come up with soon enough but for the moment they are buttoned up and playing away downstairs.

Here is what I came up with so far.


RC
 

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Redboy said:
Not bookshelf speakers, those...

I like 'em, though. Even the blue.
Click to expand...

Yea, they're going to be big but I would like to keep it reasonable. Thats about as large as I can comfortably go in my room without eating up too much real estate.

The blue is going to stay in some fashion or another. It's an ash veneer that had been stained blue to comply with an architectural color spec and ordered as such. Somewhere along the line prior to application, it must have been changed or it was possibly miss-ordered. Very nice looking stuff IMO. I'll have to bring a sheet over and show you sometime :yes:

RC
 
Ron, you do need to build bigger speakers.

I've always used you as my "No, honey... see, those are big speakers!" point of reference and that line isn't as effective as it used to be around here. :sigh:
 
Dang Ron, I have a set of boxes that could be yours for a 12 pack, if you were just a bit closer. Now that I think of it I have a pair of 15 TRX's in the same room as the boxes, Hmm
 
brainsmasher said:
Dang Ron, I have a set of boxes that could be yours for a 12 pack, if you were just a bit closer. Now that I think of it I have a pair of 15 TRX's in the same room as the boxes, Hmm
Click to expand...


Hey thanks for the offer anyway :yes: This is the way it aways works, Brian. The perfect solution is usually available for peanuts (beer in this case) but it ends up being a few states away :D

Unless something ideal shows up in my backyard I'm going to build anyway. If I play my cards right I should be able to use them for my University 315-C's also if and when I find another.

RC
 
If you have a DMM, an AF sine-wave generator (or s/w for your 'putes soundcard) , and some spare change (for the added mass method to determine Vas), yes, you, too can estimate T-S parameters, y'know?

http://sound.westhost.com/tsp.htm

It's fun! Kids, try this at home!

tsp-f2.gif

http://sound.westhost.com/tsp-f2.gif

If you don't need accurate impedance measurements, you can get away without the precision resistor (and you probably don't actually need an amplifier, either) :-P
Indeed, you can estimate Fs by ear in one of two ways: slowly sweep through the neighborhood of suspected Fs (say 40 to 100 Hz for a woofa like that) and listen for peak audio output; that's your Fs. You can even guesstimate Fs by gently (of course) tapping the cone with your finger. The sound and feel that results will give you a clue as to the resonance - try it with a fistful of woofers you have laying about (doesn't everyone have a basketful of loose drivers?) and see for yourself! :-)

EDIT: Duh :-P Just looked at the Allied model number again. If these are 15TRX OEM versions, one might safely assume that the T-S parameters are right similar to the SP15 for the woofer part. Those are available, as-is (i.e., who knows of their provenance), on Terry Gesauldo's site. http://www.vintageev.com/12trxbTSparameters.html

Terry's site sez Fs = 40 Hz, which sounds fairly reasonable for a 15" cone with a cloth accordion surround.

EDIT^2 Heh, if I had a pair of those, I'd chuck 'em into a pair of the 9 ft^3 corner cabinets Billfort designed and built and see what happened!
http://www.wardsweb.org/Billfort/
 
Last edited:
mhardy6647 said:
If you have a DMM, an AF sine-wave generator (or s/w for your 'putes soundcard) , and some spare change (for the added mass method to determine Vas), yes, you, too can estimate T-S parameters, y'know?

http://sound.westhost.com/tsp.htm

It's fun! Kids, try this at home!

tsp-f2.gif

http://sound.westhost.com/tsp-f2.gif

If you don't need accurate impedance measurements, you can get away without the precision resistor (and you probably don't actually need an amplifier, either) :-P
Indeed, you can estimate Fs by ear in one of two ways: slowly sweep through the neighborhood of suspected Fs (say 40 to 100 Hz for a woofa like that) and listen for peak audio output; that's your Fs. You can even guesstimate Fs by gently (of course) tapping the cone with your finger. The sound and feel that results will give you a clue as to the resonance - try it with a fistful of woofers you have laying about (doesn't everyone have a basketful of loose drivers?) and see for yourself! :-)

EDIT: Duh :-P Just looked at the Allied model number again. If these are 15TRX OEM versions, one might safely assume that the T-S parameters are right similar to the SP15 for the woofer part. Those are available, as-is (i.e., who knows of their provenance), on Terry Gesauldo's site. http://www.vintageev.com/12trxbTSparameters.html

Terry's site sez Fs = 40 Hz, which sounds fairly reasonable for a 15" cone with a cloth accordion surround.

EDIT^2 Heh, if I had a pair of those, I'd chuck 'em into a pair of the 9 ft^3 corner cabinets Billfort designed and built and see what happened!
http://www.wardsweb.org/Billfort/
Click to expand...


I can usually pull off Vas in WT using a varying amount of strategically placed nickles. Not sure how thats going to play out with this design though :scratch2:

I came to the same conclusion after reading Terry G's shown Fs for the SP15. Probably should have just run them through WT after I re-capped them.

At the time, I was convinced that result wasn't going to be any more than an exercise so I performed the re-cap surgery while they were still mounted in the cabs. After listening to them for a while afterward I thought otherwise. They aren't going beat up on any Altec 604's but the HF from the T35's is not as T35'ish as I though it may be even after updating.

Bill did a fabulous job with his and I had thought about that also. I could make 9 cu-ft happen with a wider front baffle and using 5' x 5' Baltic. I just had a lead on some reasonably priced Baltic that was sized to 2' x 4' and was entertaining the notion of a narrower baffle. If I used that material, 48" would be the limiting dim. so to get narrow front baffle and not exceed 48" in height O.D. I would have build a deeper cab.

I'm in a small (12' x 11' - 6") room so saving a couple of inches in depth means a lot to me.

RC
 
djnagle said:
Very nice. Is the blue Corrian face plate???
Click to expand...


Hey Dennis, I just plugged that particular blue into the drawing to get a "close enough" color match to a blue dyed Ash veneer I have around. Just wanted to see if it was going to appeal to me or not. I kinda like it :yes:

What I have is close but not nearly as Colbalt Blue as represented in the drawing. I just thought it looked cool ;)

RC
 
doucanoe said:
I can usually pull off Vas in WT using a varying amount of strategically placed nickles. Not sure how thats going to play out with this design though :scratch2:

I came to the same conclusion after reading Terry G's shown Fs for the SP15. Probably should have just run them through WT after I re-capped them.

At the time, I was convinced that result wasn't going to be any more than an exercise so I performed the re-cap surgery while they were still mounted in the cabs. After listening to them for a while afterward I thought otherwise. They aren't going beat up on any Altec 604's but the HF from the T35's is not as T35'ish as I though it may be even after updating.

Bill did a fabulous job with his and I had thought about that also. I could make 9 cu-ft happen with a wider front baffle and using 5' x 5' Baltic. I just had a lead on some reasonably priced Baltic that was sized to 2' x 4' and was entertaining the notion of a narrower baffle. If I used that material, 48" would be the limiting dim. so to get narrow front baffle and not exceed 48" in height O.D. I would have build a deeper cab.

I'm in a small (12' x 11' - 6") room so saving a couple of inches in depth means a lot to me.

RC
Click to expand...

Sounds like a plan. Or go OB :-)
 
The temporary home for the 615HC has been in the Barzilay cabs they came in. With the backs on and using the existing port tuning, the LF was reasonably good but a bit boomy. I decided to try a experiment running them open back but stuffing the cabs with acoustic polyfill and fiberglass around the perimeter and one last thickness (@3.5") after I ran out of polyfill batting.

The results are nice. It raised the LF some but at the same time smoothed out the midrange at the same time. The fill amount was just a guess but it's worked out well for this temp. arrangement.

The stock risers on the Barzilays were only about 3-4" and really wanted to get them elevated so that driver center was as close to seated eye/ear level as possible. Not wanting to build risers for these, I searched around for something suitable and came across a pair of spent Wharfedale W70 cabs I had not tossed yet. their 24" height turned out to be exactly what I needed for the Barzilay width. Laying them on their faces gave me a 14" riser.

It almost looks like they were meant to be. Man, I just love re-purposing stuff. It's really cuts back on the pain and suffering of sending it to the dump ;)

Until I get the other cabs built, I think I'm good to go for a spell for the downstairs speakers.


RC
 

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Dang those look perfect.

I think those monster drivers showed lots of promise to my ears last weekend.

I also love to re-purpose. Wait till you get a hold of my latest. The other end of the spectrum from these!
 
ejfud said:
Dang those look perfect.

I think those monster drivers showed lots of promise to my ears last weekend.

I also love to re-purpose. Wait till you get a hold of my latest. The other end of the spectrum from these!
Click to expand...


It worked out well :yes: I had forgot about those W70 cabs when I talked with you about risers for these last week. Adding that last layer of fiberglass batt to the polyfill did some good things.

You need any Baltic or 1/4" ? I'm thinking about placing an order for my cabinet sheetstock with Mike over at Industrial in about a week or so.

What you got cooking? Are we finally going to see how the Saba cabs are coming along :scratch2:


RC
 
I need some 1/8" for sure and probably some more 3/4". Keep me posted.

Yeah, the Saba's will be moving forward soon. The new project is a whole different monster.
 
Redboy said:
Those cabinets look really cool that way, Ron!

Hmmm... :scratch2:
Click to expand...


I know! I wanted to get these off the floor for the last couple of weeks but couldn't think of anything I had that would work or at least look reasonable for the time being.

I started to pull the remaining drivers out of the W70s last night when the light bulb finally turned on. Here I had been tripping over the solution in the back corner of the basement for months :D


RC
 
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