Ok thanks Earl. I?ll look into testing them myself.
The simplest ( not necessarily the cheapest ) is to buy a gizmo ( that interfaces to your PC ) that will do the measurements for you.Originally Posted by Elitopus1
DATS 3 ( not yet released ) is one such device;
https://www.parts-express.com/dayton-audio-dats-v3-computer-based-audio-component-test-system--390-807?gclid=Cj0KCQjwi7DtBRCLARIsAGCJWBocJeCQldVCdiOL luWRFm13ZxHOpI8X1HGGyjUvSasHbpVfl-cZYSMaAuZsEALw_wcB
The simplest ( likely the cheapest if you have a reasonable soundcard ) is to download REW ( Room EQ Wizard ) and setup a TS measuring jig ( following the online directions ).
http://www.roomeqwizard.com/
Ex ( Hostboard member MoldyOldy ) has a related thread found at the following link;
http://www.audioheritage.org/vbulletin/showthread.php?14472-Measuring-T-S-parameters
Ok thanks Earl. I?ll look into testing them myself.
Mine work hardened with age, so at this decade plus later date, I have to wonder if they're worth saving.
Yes, normally I would have recommended this except he says one is much stiffer than the other, so not going to get a usable measurement, what with Fs higher, Cms lower, so what am I missing?
Res = Z0 ? ReQms = Res / (BL2 * Cms * 6.283 * Fs)Qes = Re / (BL2 * Cms * 6.283 * Fs)Units of measurement :
- Res is calculated by subtracting the voice coil resistance (Re) from the impedance peak measured at resonance (Z0) ? all measured in ohms.
- BL -> Tm (Tesla * meters).
- Cms -> m/N (meters/newton).
- Fs -> Hz.
Qts = (Qes * Qms) / (Qes + Qms)
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
^That makes sense about the Ts measurements being different because if the suspension compliance difference. It makes me lean towards just sending them to GPA.
One other question. Some of the newer 604 variants come with a spider between the horn and the cone. Is there any benefit to the spider versus the felt that my speakers have?
Depends on the mass, compliance of each and since higher Vas drivers can in some ways track the signal better, especially if allowed to 'breathe' [Vas/1.44 or max out at Vb = Vas], I prefer as high as I can get.
Mine are rebuilds matched at 20 ft^3 because it was my understanding that this was pretty much the limit for 515Bs only to find out later that new ones were up to ~35 ft^3!, though listed as ~20 ft^3.
Regardless, can't answer your Q per se, especially since there may be other issues 'at play' I'm not aware of [no 'hands on' experience with rebuilding/modding duplexes].
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Given the logistics involved, i'd be tempted to have GW rebuild them, analyze them, and go from there. He may also know where you can have them drained and re-charged more locally to you.
Just my .02....
Not all vegetables make good leaders.
So have Gordon recone them, and then check the Ts specs on them to see how far off they are. I?m assuming to do this I?d have to send some HF diaphragms with them so he could check the horn drivers too right?
So then back to the cone kits. Is it worth it to use the GPA kits? I assume it would add about 200$ to the cost to recone the pair, versus parts he has in house. I know the cone is just a paper cone, and I?m sure one that weighs the same could be easily sourced. The same with the surround and spider. So that just leaves the VC. Anything special there on the GPA version?
And probably the biggest difference between the GPA cone kit and generic parts, resale value. I?m sure with aftermarket parts that will take a hit. I do want to keep these, but I don?t like the idea of devaluing something just to save a few bucks now.
But then again, once they go back in the cabs you never see those little numbers on the back of the cones
I wouldn't assume that GordonW is restricted to using generic parts for an Altec recone .
Gordon may have access to bona-fide GPA kits ( at a service outlets discount ).
You won't know unless you ask him.
That said, the user who's truly concerned about resale value is going to want to keep ( save ) the original voice coil and paper cone.
That means changing out the suspension parts.
This is much more labor intensive ( ie; costly ) and might well be something that Gordon is willing to execute ( or not ). Need to ask.
What are the current part numbers printed on the back side of your 604 cones?
If they contain 35400 anywhere then those aren't worth trying to save ( since that's the current go-to cone number > indicating yours have already had a recone ).
Simply Speakers gets 84 bucks for a complete 604 kit including the proper wide gasket, i think you have to buy adhesives and sealant separately.
I would defer most of those questions to whomever actually does the job. Simply suffice to say that since they're already a custom driver versus a stock 604G, i'd have less hesitation using aftermarket parts especially under the guidance of GW or peers.
This of course is just my .02.....
I've owned no less than 3 pair of 604-8G.
Do i love them? Of course i do, with the caveat that love can be a very subjective thing, and sometimes grows stale.
Would i pay 400+(less shipping) to LF re-cone a pair today? Not likely.
Not all vegetables make good leaders.
Earl
I reached out to him on AK. Just waiting to hear back now.
He has repaired speakers for me before by reusing the original parts. I had a pair of 616-8a that both had coil rub. He was able to disassemble them and reuse the cone and VC, and he only had to replace the front spider. It was similar in price to a recone. Just more money in labor and less in parts.
My 604 do not have original cones. They have variations of 35400 part number you mentioned. I bought them from eBay from two different sellers. When I got them they had no HF diaphragms so I used a pair out of some 802 drivers I had.
The one 604 had a broken HF cover, which makes me think it was handled roughly at some point, but not enough to shift any magnets etc.
I will definitely go over all my options with Gordon for reconing.
I was looking at shipping prices today, and to send them to GA it?s 37$ per woofer one way. To OK it?s 58$ per woofer one way. So you figure about 80$ difference just in shipping.
I was also looking around at places that would do a remag. There?s a small speaker shop in Indiana that could do it. But that?s just as far as Oklahoma. There has to be someone in Florida. I?ll just have to ask around.
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