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RF-7 crossovers (upgraded)


Deang

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hi,

I would appreciate if someone who made the measurements of the two inductors of the High pass could give me the values. The first one bypasses the circuit after the 1 ohm resistor and 5 uF cap (+ input) and the second corresponds to the ICR combination parallel with the TW.

I read that the value of the low pass cap is 0.75uH. Is it exact ?

Just an other question : when 2 capacitors are put in parallel to produce the value of the capacitor to change, is it a better way to use about the same value for the capacitors or very differents values ?

Anyone has evaluated the effect on the sound of the cable terminal made in poor (i suppose) metal ?

Many thanks,

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Old Thread Frank, early work. Two things I did early on that I no longer do, 1) change out the inductors, and 2) parallel two high quality 9uF values for the single 18uF in the LCR circuit.

For a short time, I had Madisound custom winding the two small inductors for the tweeter circuit. However, what I was getting was identical to what Klipsch was already using. IOW's, nothing "special" in that they weren't perfectly layered or dipped in varnish, etc. So, I quit messing with it. There are no aftermarket suitable replacements for those. I believe that inductance, as well as DCR should be spot on. Also, the parts are positioned in such a way that there is some mutual inductance, and Klipsch accounts for this -- so, better to leave well enough alone here. I also used to change out what I thought was an iron core for an air core in the woofer circuit. I later found out the stock part is a steel laminate type. Saturation points are much higher for steel laminates, so I dropped the air core in that position. There might be some marginal improvement by using an air core there, sometimes I thought I heard a difference, sometimes I didn't. I figured if I have strain a ******** to hear the difference -- it isn't worth the effort.

In the LCR circuit for the horn, I used to match the quality of the capacitor in that position to the same quality I used in the series caps. I started with an 18uF ClarityCap, but the cap was so big I had to modify the terminal cup by extending the distance between the boards with longer spacers and screws. The stock screws are #4, and I could only find the longer screws I needed in #6. Since they screw down into hard plastic posts -- I had to drill out the posts so they wouldn't split. I found this out the hard way when I first did my own networks, where I didn't drill out the holes a bit bigger first. Some might remember I eventually built mine on wood boards, now you know why.:) After doing about a dozen sets like this I threw in the towel and started paralleling up two 9uF Auricaps. This lowered the height requirement so I could use the stock screws. However, it was more expensive. So, less labor, but more cost in parts.

At some point, I decided to rebuild my networks again, but with different caps. While I had everything out I decided to play with the cap and resistor values in the LCR circuit. When I play around with stuff I typically use less expensive parts, because they go in and out a lot. I did this over the course of a week or so, and when I was all done and built the networks -- I found I couldn't hear a difference between the Thetas I had just dropped into the LCR and the Dayton Audio I had been using to play around with. So, caps in series with the horn had great impact, caps in parallel with it had little. I now use an 18uF Jantzen in that spot.

Pricing has fluctuated over time as I've changed vendors and parts, and shifted the balance between labor and parts. For example: I used to use Auricap, but the boneheads could never get an order right. I got tired of getting 5.6uF values for the 5's I needed. I'd send the 5.6's back, and the 5's wouldn't show up on the next order. The relationship got strained when I refused to pay until they gave me the caps I was supposed to get. So, I went with Kimber, which meant paying more. However, the guys at partsexpress pull the bins for me and let me measure the caps right at the counter. I will probably start using the Auricap again in the next couple of months, but not for reasons related to the RF-7.

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Dean,

Without reading this entire thred, all I can say is why suffer the brain damage you are going through? Just mount the circuit boards on plywood and use wire jumpers to soldering lugs to attach caps.

Check out these crossovers that I upgraded on a set of JBL's.

Easy as can be. This would have been really difficult on the factory boards because they used electrolytes. The new larger board easily fits in the speakers.

Chris

post-10861-13819297876296_thumb.jpg

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Yes, micorfareds: uF or mFd

The inductor values are in millihenry. I didn't need to put the zero in them. So, .30mH, .125mH, and .75mH.

DCR = DC Resistance, determined by the thickness and length of the wire on the spool. It makes up part of the resistive component of the circuit. Using inductive values that are the same, yet achieved with different sized wire -- alters the DCR or resistive component. This is tied to the 'Q' or loss factor in the tweeter circuit. In the woofer circuit, the DCR of the coil is used to align the driver, port, and cabinet. So, leave them alone!


Nice job Chris. I think I'll take a pass though on doing it that way for Reference.

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One more thing: If you would like to hear a bit better integration between the horn and cones (bring the top down just a little), parallel a 10 ohm resistor with the 2 ohm resistor located next to the 18uF capacitor on the bottom board. If you can find a single 1.75ohm resistor, that will work as well.

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In fact, i would like to make a totally new filter outside the loudspeaker(but with same value especially for the inductor) to keep unaltered the original Klispch crossover.

I would like to find inductor with about the same characteristic (DCR, L) as you have mentionned for the bass pass. Is it possible to find this kind of inductor ? If not i will use the original inductor.

I expect to use caddock resistor (1 ohm 25 w) for the high pass with caps which i have to choose (auricap or Mundorf siver/oil very but very expensive !!!).

Is it possible to find some air inductor (.30mH and .125mH) with about the same characteristic ?

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  • 1 month later...

Hello,

I think there is a mistake on the picture for the low pass filter.

The 1 Ohm resistor should not be parallel to the woofers but should take place between the capacitor and the - of the woofer (CR // woofers).

An other detail on my filter is that the tweeter is plugged in opposite phase respect to the woofers.

Bye

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  • 2 weeks later...

Hello,

My modified RF7 crossovers are finished.

I use Intertechnik AudynCap MKP+ capacitors (5 et 12 uF) (http://www.riviera-acoustics.com/catalog/product_info.php?cPath=46_35_57_50&products_id=203), intertechnik inductors parallel to the TW and Caddock MP825 resitors. For the capacitors which are parallel to the TW, i use Audyn Cap MKP QS (less expensive)

The 0.75 mH inductor has been kept but the capacitors parallel to the woofers has been changed by AudynCap MKP+ capacitors.

The componants have been soldered directly wituhout using printed circuit.

HF section of the crossover

I modify the wire between the TW and the crossover.

The low pass filter is inside the loudspeaker, the high pass outside.

The results are smoother and more accurate high frequencies which allows better rendering of voices, cymbals and stringed instruments.

More clarity from medium frequencies to high frequencies.

Bye,

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  • 2 years later...

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