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Recapping AR-4X

Before and After

Wiredbecker's AR4x projects:

1) Morel DMS-37 and JBL 116H

2) BMS 4540nd on JBL OASR "Dr. Seuss" horn and JBL 116H

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Honestly though, I can only claim the Seuss horn ZL4's as my project. The Morel ZL4's are all Zilch. Both however sound fantastic.
 
Well, my son, Andy, and I got the big stuff outta the way, anyhow. He bought the XD120's, I contributed the AR's. We'll be starting the fun stuff very soon!

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That's gonna work, I betcha, using the E'Wave crossover, according to Skywave's initial evaluation of the combo.... :thmbsp:
 
Get L-Pads with 1" long shafts, and you may be able to mount the works in the existing input cutouts.... :yes:
 
I tried the XD120 on top of the upside down 4x with my 604-8K crossover and it worked, although I had to really step on the HF to balance out with the LF. Sure the bass is a bit shy, but we've got a couple subs laying aroud that we can use to take care of that, if we really want to. It sounded nice!

I'm impressed with what a total of $25 (for 1, including the AR) got us. This is fun!

Next, we're off to buy the correct xover parts and get the surround for the bad woofer on the other one.

Hopefully, by next weekend I'll have some real progress to show...:)

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This is an AWESOME thread!!! I have a pair of these I was thinking about restoring and I am so glad I found this!:banana:

Also good info regardless.:thmbsp:
 
Zilch,

I put the order together at PE for the crossovers, I will probably be ordering towards the end of this week. My son's back at the institute of higher learning now, so I'm probably gonna just go ahead and do this project as his proxy.

The only concern I have is that the frequency range for the XD120 is different from the D210Ti/PT combo...2KHz-18KHx centered at 3KHZ as opposed to 1KHz-21KHZ centered at 2KHz, respectively.

I'm not real sure if I ought to change the C1&C2 and L1&L2 values to try and compensate for the difference? Unfortunately, I don't have any way to RTA, and confirm any changes.

I saw that you had actively xovered a pair at 2K and IIRC Skywave-rider posted an RTA that was pretty flat, but I don't remember if Skywave-rider was using a crossover or RTA'd the drivers separately.

Edit: I found the data I was looking for:

http://www.audiokarma.org/forums/showpost.php?p=2345770&postcount=3140
 
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If you research Jack's development of the E'Wave crossover, you'll find that the electrical highpass is much higher, up around 3.5 kHz; that's part of the HF compensation, as these drivers have excess response in the region of 2 kHz that must be corrected. Whether you do it entirely within the HF comp filter, or make that less of a task in combination with the highpass is inconsequential.

Indeed, E'Wave is not "textbook," but this approach goes way back to the earliest days when Altec (and others) first determined that the excessively forward upper midrange produced by compression drivers was undesirable. It took another 10 years to recognize that HF comp could be used to extend the VHF of drivers capable of delivering it, once the prevailing supposition that response above 10 kHz was unnecessary was disproven.... :yes:
 
Fran604g said:
...

I saw that you had actively xovered a pair at 2K and IIRC Skywave-rider posted an RTA that was pretty flat, but I don't remember if Skywave-rider was using a crossover or RTA'd the drivers separately.

Edit: I found the data I was looking for:

http://www.audiokarma.org/forums/showpost.php?p=2345770&postcount=3140
Click to expand...

I don't remember if I ran the driver for raw response. But I do remember posting RTA using the ewave crossover. To get flattest response, I moved the mouth of the waveguide 1/2" back from the front of the baffle. It will probably be different on your setup.

I also posted RTA of this driver on different waveguides, so check out the applicable post.

EDIT:
Here's the RTA:
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Zilch said:
If you research Jack's development of the E'Wave crossover, you'll find that the electrical highpass is much higher, up around 3.5 kHz; that's part of the HF compensation, as these drivers have excess response in the region of 2 kHz that must be corrected. Whether you do it entirely within the HF comp filter, or make that less of a task in combination with the highpass is inconsequencial.

Indeed, E'Wave is not "textbook," but this approach goes way back to the earliest days when Altec (and others) first determined that the excessively forward upper midrange produced by compression drivers was undesirable. It took another 10 years to recognize that HF comp could be used to extend the VHF of drivers capable of delivering it, once the prevailing supposition that response above 10 kHz was unnecessary was disproven.... :yes:
Click to expand...

OK, that makes a lot of sense, I wasn't getting that part.

Thanks!
 
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skywave-rider said:
I don't remember if I ran the driver for raw response. But I do remember posting RTA using the ewave crossover. To get flattest response, I moved the mouth of the waveguide 1/2" back from the front of the baffle. It will probably be different on your setup.

I also posted RTA of this driver on different waveguides, so check out the applicable post.
Click to expand...

Thanks Skywave-rider!
 
Zilch said:
---snip---116H and 116A show up frequently on eBay for cheap, just needing refoam, typically. The T/S parameters are the same. "A" is for alnico, in this instance. "H" distortion is lower.
Click to expand...

Zilch- As I am so impatient (and somewhat doubtful about actually getting a pair of 'matched' used and truly 'working' speakers from an unknown source), is there another woofer you'd suggest that would fit the duty? A "new" speaker, maybe even something available at Parts Express, as I like dealing with them.

And as long as I brought it up, I have a pair of ADC 303a that will experience the rath of my table saw and receive these new drivers. The cabinets appear to be just slightly larger than AR4x's (at 23-3/4 T, 12-7/8 wide, 11-3/4 deep). Do you think I can get reasonably similar performance out of the same drivers and crossover parts that have been discussed here? Or should I start over?

Brian
 
There are lots of options if you're willing to vent the cabs, but few modern woofers are made with the requisite parameters for small acoustic suspension alignments. Next time Ken Kantor comes over, I'll ask him, or you might send him a PM asking for him to post suggestions here for a suitable new 8" to retro into AR4x and similar. RayW may know of some good choices, also. They've got to play nice up to ~1.6 kHz.

There are a couple of high-Qes Goldwoods that might be worth a look:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-315

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-355

If you're willing to vent, this Pioneer might be good:

http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=290-042

Others at Madisound, e.g.:

http://www.madisound.com/catalog/product_info.php?manufacturers_id=150&products_id=848

For any of these, I'd run the box models to verify before purchasing.... :yes:

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