Reviving vintage JBL cabinets

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I have a pair of old JBL reference 502vx cabinets.

http://www.jbl.com/images/media/502VX%20ts.pdf link for reference.

I want to put new drivers in it. The crossover is very simple. first order low pass and second order high pass. Is it worth trying to drop in new drivers with the existing crossover or should I go ahead and select some drivers and design my own crossover for them.

the box is approx 1.54cube and has a 2" by 5" long port.

Either way I could use some help in selecting drivers and ultimately the design of my crossover. My first question is for the tweeter. The hole for the tweeter is actually 3" Is it desirable to go with a 3" speaker that could be crossed lower... say around 500-600 so the woofer can be crossed lower or stick with a tweeter in the 2k+ range? I realize I'll need to enclose the speaker to isolate it from the woofer.

If making a crossover I'm going to stick with a 2nd order for both low pass and high pass basically following the guide in the sticky.

This is my first diy and I'm just looking to salvage these cabs my roomate was going to throw away. Id like to keep this under 150USD which seems easily doable via partsexpress.
 
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I guess I was a little too vague in my first post. I've decided to go for a new 2-way and trying my hand at making a crossover. I'm looking at the following drivers.

Dayton dc28f tweeter.
http://www.daytonaudio.com/media/resources/275-070-dayton-audio-dc28f-8-specifications-46121.pdf

mcm 55-2950 8" woofer.

http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/55-2950.pdf

following the crossover without measurements guide I have come up with the following values for a crossover at 2500hz.

these are calculated and ill need to closest avail part.
to flatten woofer impedance a resistor of 9ohm and a capacitor of 13uf

woofer inductor .51mH inductor.

use a 20hm resistor to flatten tweeter.

tweeter crossover using approx. 6.88uF cap and .59mH inductor....

I don't have a resistor in series and so I used the 20ohm instead of 10ohm resistor to prevent too low of an impedance. I did this because the woofer is rated at 94 db and the tweeter at only 89..

Is this okay? can this be a bit of a baffle step? Or do I really need to figure out a different combination with a tweeter that has a higher spl that I can then bring down. This seems to be a popular tweeter on parts express so maybe someone can chime in.

theres a 89 db woofer on mcms site, but its vas is a whopping 98 liters with a qts of .4529.... My box is only about 1.54cubes... ported.
 
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Hi,

I'd wouldn't take MCM's specs sheets too seriously.
That 8" is a PA drivers and wont match the cabinets well.

If the box really is 43L internal then its tuned to ~ 30Hz.
Looking at the only picture I can find it doesn't seem that big.

Choice of the bassmid is critical, and sadly not many
genuine 8" bassmids are made nowadays, most can't
do mids, and the ones that can are not cheap, using
all your budget and more in most cases.

Best guess :
https://www.madisoundspeakerstore.com/approx-8-woofers/silver-flute-w20rc38-04-ohm-8-wool-cone/
Tweeter possibly : (basically just great value)
https://www.madisoundspeakerstore.c...hi-vi-k1-1-fabric-dome-tweeter-116-mm-flange/
see : http://www.zaphaudio.com/tweetermishmash/compare.html for curves.

And yes your modelling must include baffle diffraction and some BSC.

rgds, sreten.

http://audio.claub.net/Simple Loudspeaker Design ver2.pdf
FRD Consortium tools guide
 
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understood on the woofer. I figured 10 bucks was too good to be true lol. Any particular reason for that tweeter over the Dayton? what If I upped my budget and went with say...

http://www.parts-express.com/pedocs/specs/295-332-dayton-audio-da215-8-specifications-46942.pdf

It matches the Dayton tweeter spl and has a vas 1.51 cubes which is close to my box. My understanding is if your around the .4qts mark a vented enclosure should be around the vas volume and larger for higher qts values or smaller for lower qts values. I realize this is very crude, but this is my first diy.

The woofer aside is their anything inherently wrong with my crossover calculations for the tweeter? With the lower spl Dayton woofer that leaves me room to change the resistors around depending on how it sounds.

Also I believe 24w of resister for the zobel is fine for the woofer and 10w in parallel with the tweeter is fine. The sony receiver is rated at 100w and I don't listen to this very loud.

also yes the cab is 1.54 or very close. The pdf in my first post has the actual box dimensions although it will not load now.

21.5" x 13.5" x 11.1875" I accounted for what looks to be .5" for the cab and 3/4" for the baffle.
 

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understood on the woofer. I figured 10 bucks was too good to be true lol. Any particular reason for that tweeter over the Dayton? what If I upped my budget and went with say...

http://www.parts-express.com/pedocs/specs/295-332-dayton-audio-da215-8-specifications-46942.pdf

It matches the Dayton tweeter spl and has a vas 1.51 cubes which is close to my box. My understanding is if your around the .4qts mark a vented enclosure should be around the vas volume and larger for higher qts values or smaller for lower qts values. I realize this is very crude, but this is my first diy.

The woofer aside is their anything inherently wrong with my crossover calculations for the tweeter? With the lower spl Dayton woofer that leaves me room to change the resistors around depending on how it sounds.

Also I believe 24w of resister for the zobel is fine for the woofer and 10w in parallel with the tweeter is fine. The sony receiver is rated at 100w and I don't listen to this very loud.

also yes the cab is 1.54 or very close. The pdf in my first post has the actual box dimensions although it will not load now.

21.5" x 13.5" x 11.1875" I accounted for what looks to be .5" for the cab and 3/4" for the baffle.

Hi,

The designing without measurement post is OK, but
takes zobels far too seriously, they are not needed.
look at the designs here : zaph|audio

The PE 8" would seem a fine choice but I'm really at a loss
sometimes about their published specifications, e.g. compare :
http://www.parts-express.com/pedocs/specs/295-335-dayton-audio-da175-8-specifications-46154.pdf
To :
DA175-8-FR.gif


Its not good for modelling without measurements.

FWIW if Seas can't make a metal 8" good for a 2 way,
nobody can, and they can't, and I think nobody can.

On a budget I'd tend towards a FAST.

rgds, sreten.
 
You never really do a proper job, you over simplify it
using a simulator that cannot use proper driver data.
Whatever system7 does or doesn't do, Boxsim can use proper driver data just fine if you have such data, and use the corresponding settings.

I don't know why you're at a loss because that's not exactly worlds apart. Scales matched, overlayed, stated invalid portions of each cropped off:
attachment.php


But...
Its not good for modelling without measurements.
I agree.
 

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Ok I toyed around with boxism and its def cool, but I don't have any measuring equipment. this is all best guess. That parts express driver isn't listed in the visaton drivers obviously and I don't even have all the values to try and input my own data such as fas. I looked up a visaton tsweeter but its vas was like 1900 and didn't seem to match up well to that visaton woofer you posted.....
 
so I used spl trace for a crude representation of my drivers and put them in boxism. my crossover is much simpler than the one you showed. can I email or otherwise get the project file to you? the frequency response is fairly flat, but I'm sure theres more to it than that. I did not upload an impedance file though. I also had to guess at the tweeters excursion as it would not do anything without a value there. I used 1.0 as the visaton was 1.1.....
 
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Dayton dc28f
Dayton da215-8

I uploaded a trace of the impedance graphs also. Another concern is the modeler lets you choose ported enclosure but does not have you put in any parameters for the port? I can give you the project file if your willing. pay no attention to the wire connection between tweeter and woofer. I must of somehow put It there when copying.
 

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Thank God for that. :)

I used the TW 70 - 8 Ohm to model the generic 90dB cone tweeter. It's not a bad assumption.

I suggested the phenolic ring tweeter because it fits. But play with some values.

IMO, the fourth order LR4 tweeter filter is the best sounding one. But the steep third order treble sounds very good too. I didn't model it exactly because it's not my project. Phase alignment matters.
 
I must be doing something different. Using the sample xo you showed before and using the visaton test drivers without changing anything I get a graph like the one attached. was the xo you showed supposed to be appropriate for the ws200 and the tw70?
 

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