Xover cap suggestions!

[kegman]

I allready posted this in the 2 channel section when I noticed this catagory!

Sorry haven't posted much here and still learning!

Anyway here's the question!

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I've got my rc7's apart right now and I'm going to do some tweaking

on the horn part of the xover and was wondering if one should leave

or replace the mica caps with poly's. (2 rc7's as mains)

What I'm planning on doing is Bypassing whatever caps I use with pio's

that I have and up the 2 ohm resistor in line with the horn to a four.

The speakers are a little to bright for me and I figured the pio's may

give me a little more juice per say and the extra padding on the horn

to tame the brightness a little!

Any thoughts? Sound about right?

I've got mills & dale wirewound resistors to replace the originals with.

And I have plenty of quality poly caps in various sizes and brand.

The pio caps I have range in brand but mostly around .10uf in size.

[Al Klappenberger]

I would not even us PIO caps for the out-house door knob! All they are is a cap with a resistor in series with them. That is what a lossey cap is! Use a good polypropylene cap and an L-pad later if the level is too high. This lets you adjust the level to your liking with the L-pad and keep the filter the cap is part of working properly and provide it with a good load too!

Al K.

[kegman]

Haven't heard that one before but I'll keep it in mind anyway!

Thanks for the reply!

[Deang]

I would only consider the PIO option if you could buy new Jensens of the correct values, ditch the PCB's, and build point-to-point on separate boards. If doing this, you wouldn't want to make any changes to circuit. The resistive element of the PIO's is higher (like Al explained), and making any other changes in resistance is just going to emasculate the speaker.

Based on what you posted, and what you emailed me -- I don't think you've done enough homework! All you want is a cleaner sounding pair of RC-7's, if you start jerking around with the circuit without knowing exactly what the effects are -- you're going to end up with Frankenklipsch.

This is what you should do:

I would leave the LF section part of the board just the way it is. Modding that section is a nightmare, and the benefits are marginal. The ears just aren't very sensitive to cap changes in the LF section of a network. I mod that section as part as what I offer, but it's not easy and it's not fun. You've been warned. One thing you might do is desolder the black cap stacked on top of the other, and reglue it with a quality clear silicone adhesive. I've done about a 1/2 dozen RC-7's and every single one had that top cap floating loose on top of the adhesive.

Concentrate your efforts on the HF section where the changes will drop your jaw, and give you exactly what you're looking for.

Do NOT change the value of that first resistor (the one next to the orange oval caps), leave it at 2 ohms. The resistor value you want to change is on the other side of the board (next to black mylar cap). Change that value from 2 ohms to 1.66 ohms, which you do by paralleling a 10 ohm with the 2 ohm.

All of the parts you need come from www.partsexpress.com

Mills non-inductive types

(4) 005-2

(2) 005-10

Kimber capacitors

(2) 027-866

(2) 027-890

(2) 027-452 (which you will parallel with 027-866)

(4) 027-866 (which you will parallel together)

That's it. Not inexpensive by any means, but worth every dollar. If this is too much money for you, use the Dayton Audio capacitors -- which will get you %95 there.

BTW, you will also have to mod the terminal cups. The top board won't go back on after the mods (the stock screws and spacers no longer provide enough clearance). You'll have to go to lowes and buy longer spacers, and #6 2.5" wood screws. Go slow screwing them in or you'll split the plastic posts. I've had several delivered to me already split -- so examine yours and have Klipsch replace them if damaged.

[kegman]

Dean thanks for the info!

I do not intend to mess with anything but the horn side of the xover!

(That's the only area I feel unsatisfactory for my listening taste)

The 2 things I am trying to accomplish with modding the xover are.

1. loose a little on the top end (just a little too bright for me)

2. smooth out the performance on the horn, more mellow/musical!

As modding the xover is relativly easy I found no problem with

experimenting with the series resistor size and brand. But!

I don't really have a problem with the price of the parts if the

outcome is what I'm looking for or find it a substantial upgrade.

I just find it tough to buy expensive parts to experiment with!

All of the above upgrades you mention I will look into.

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I do have another question though, as the smaller of the two caps is the

last cap before the driver, any thoughts on just replacing that one with

a Jenson pio cap? And which jenson pio's do you suggest?

Thanks for any and all suggestions I do take them all serious!

[Deang]

The two Jensen capacitors stacked on the front of the board in the attached picture are 2uF's. Forget the Jensens, you'll never get them on those boards. Do the mod the way I suggested, if the top is still too hot, then drop the series resistor by .5 ohm. Small changes make big differences.

[kegman]

Hey thanks for the pic your right those babies are huge!

Dean I'm a little confused about this statement, sorry if I'm asking to much!

But I am a hack at best when doing this stuff but I figure eventually I'll learn!

Anyway's this!

"if the top is still too hot, then drop the series resistor by .5 ohm"

It would seam if I lower the resistence on the series resistor going into the

horn then I would get more out of the horn not less, Am I missing something?

[Deang]

lol - no, you're not missing anything, I am. Raise it .5 ohms.

[kegman]

Thank you very much dean! I've been a computer tech for about 20 years

now and have worked at a couple places repairing electronics, radios

and such so I thought I had that part figured out. (I miss type all the time to)

I can trace my way around a curcuit and have recently been doing some mods

/repairs on my tube equipment plus some speaker upgrades but by no means am

I a master at this stuff, still learning as I go but I can solder with the

best of um so I don't mind experimenting/hacking.

Besides that I can't leave anything stock! Allways have to take it apart to

see if I can improve it.

And lately I like what pio's have done for coupling caps in my tube equipment

so I figured it was time to mess with the rc7's. (built me a center with parts)

Right now I'm running an antique sound labs 300b (original design no knobs)

and I picked up the anthem pre 2l as I think it was you who also liked these

for the price of $500 in really good condition with the remote.

I've also got plenty of other amps I've tested these and many other speakers with!

From stock to modded st70's to totally rebuilt golden tube audio se40's to a rogue

88 tube amp and other various preamps.

I'll keep experimenting with these till I get um where I like um!

[kegman]

I was doing some cap prices when low and behold

welborne labs has all there kimber caps 50% off!

I ordered 4 of each 1uf 2.2uf 4uf 5uf 6uf plus

some mills resistors and a couple other things.

came to $157 plus a discount and I'll have extras!

There limited in whats left and I had to buy what

they had but for the discount I jumped on it as

I'll have extra for other projects.

Pretty cool!

[kegman]

What about repacking the inside of the cabinet as klipsch does not put much in there?

I repacked the walls and back with half thickness

pink insulation. Any thoughts?