AR4x pair already "worked on"

[stupidhead]

Hello folks. I have recently dug out some old projects that I had shelved years ago. My first pair that I have questions on is this pair of 4x. After taking off the gills I see that a PRT driver has been installed in both. Looking at the xover it looks as though the original cap has been cut out of the circuit and an odd looking cap? has been put in the circuit. I no longer have diagrams of various xovers and am working only from memory but I thought it is a #5 inductor, where this is a #4.

What should I do in the way of rewiring this xover and get the best outcome. I will pull the pots and. clean/replace as needed.

Geoff

[stupidhead]

if you look close you can see a couple of the woofer t nuts are dislodged and baffle is damaged. I plan to redrill and set the nuts in virgin baffle material. The original nuts should be reusable.

[AR55]

The attached photo shows the values of the capacitors and the #5 conductor (1.13Mh) in the 4x crossover.

Below is a link to a good discussion of the 4x crossover by ra.ra in 2013:

4x-unfamiliar-crossover

 

[lARrybody]

My AR 4X has a #4 coil, even though the crossover schematic shows a #5 coil. I used a 20uf Dayton poly and a Lpad.

[stupidhead]

Hey now, thanx for the input. I seem to recall that there were xover changes over the production of this model. I found the attached diagram which I believe is my particular situation. I saw something about driver polarity being toyed with a related discussion?

My question is that with the PRT in the mix, do I still want a 20MFD cap? They are not particularly expensive and if a 4 ohm version would be better I would consider that. Any other "mods" for this situation? 

 

 

 

[DavidR]

23 hours ago, stupidhead said:

and if a 4 ohm version would be better

I copied the Athenos pages to my hard drive before they went off line.

They list both AR4 models as 8 ohm speakers. I don't think you would gain anything by going 4 ohm on the tweeter.

I see no reason to change the cap value either but you could experiment.

[stupidhead]

Hi David et al,

The 4 ohm question is a result of seeing some threads where the PRT is said to be harsh compared to the OEM driver. My sense of it is that maybe the 4 ohm is not as brash in this circuit as an 8 ohm might be in the same circuit.

In all cases the cap has been eliminated previously for some reason. I can easily cobble a 20uf in for the tweeter path, just not sure if there is a better or different value cap that would be a better choice for this combination of drivers?

Geoff

[RoyC]

9 hours ago, stupidhead said:

Hi David et al,

The 4 ohm question is a result of seeing some threads where the PRT is said to be harsh compared to the OEM driver. My sense of it is that maybe the 4 ohm is not as brash in this circuit as an 8 ohm might be in the same circuit.

In all cases the cap has been eliminated previously for some reason. I can easily cobble a 20uf in for the tweeter path, just not sure if there is a better or different value cap that would be a better choice for this combination of drivers?

Geoff

Hey Geoff,

The PRT replacement tweeter will never be a sonic match for the original...and I suspect the smaller value replacement capacitor you found was an attempt to calm its response down in the upper mid frequencies. Its primary value is that it fits the cabinet hole.

Imo, your thoughts regarding trying a 4 ohm version and/or experimenting with the crossover are worthwhile, but can quickly become a rabbit hole. There are a couple of old threads somewhere suggesting specific crossover changes to use with the PRT type of tweeter. If you can find them I would go that route before doing anything else.