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Electrovoice CR-35 xovers schematic anyone?

Patrice B

Patrice B

AK Subscriber
Subscriber
Hello,

I asked Mr Bob Crites about it and he replied that I'm better calling Electrovoice directly.

However, I'll take achance here first.

Copy and paste of the mail sent to Mr Crites:

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Hello,

I'm curious to know if you have some CR-35 crossover schematic available (8 ohms)?

I want to rebuilt mine because I'm not sure that the 50 years old caps in there performs as they should. I hear some harshness in the mid/hi range. This is with the following components:

- 2 custom big boxes loaded each with an EV SP12B and a TW35 (8 ohms);
- the speakers are feeded with an Eico HF-81, freshly rebuilt (all caps and resistors).

Sure, the fact that the Eico has now some modern caps could brighten the sound but at least, by building a new set of xovers, I would be able to compare...

Stupidly, I've bought a replacement set of CR-35's on the Bay, thinking that I would open them and just replace the caps, but it looks a tedious job as those things are completely closed and as I heard, filled with black tar inside.

So, I would be better to build them from scratch.

The only approaching schematic I've found is located here: http://www.users.cloud9.net/~pastark/ON63f123.jpg. It's a CR-35 schematic that came from a Schober organ thingie so I'm not sure if the xovers are ecaxtly the same as mine.

What made me doubtful (about the values of the xover in the organ) also is that I've entered the parameters of my drivers on an online xover calculator ( http://www.ajdesigner.com/crossover/crossoverfirst.php ) and ended with 5.6 mfd and 0.37mH. The guy with the Schober has 2.8 mfd and 0.37mH in his CR-35...

**I could also play with my Lpads as I remember having set them at full treble when I acquired the speakers (one year ago). However, they are inside the boxes and I have to unscrew the back panels and fiddle inside the cabinets to reach them (did I say "custom made"...). Lazy me:)

Thanks.

Patrice

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The Electrovoice speakers in question were discussed here last year:

http://www.audiokarma.org/forums/showthread.php?t=282177

Thanks a lot,

Patrice
 
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Ok, no luck!

I've called the Morrilton (Arkansas) EV plant asking about it but the nice service rep didn't find the file after intensive search.

Next, I could try to pry/open the two xovers I've bought on the Bay and use them as my schematic to build new ones.

But, the question is how to proceed to open them as they look completely sealed and maybe soldered...?

140.jpg


Thanks.

Patrice
 
Last edited:
Without any schematic from EV, I'll go following the one in the Schober organ:

I would use a .36mH coil from "in" (+) to "lo". Then, a 2.8uf (in fact, I'll have to parallel some values) in serie with a 8 ohms L-Pad going from "in" (+) to "hi". Strange is the fact that the Schober organ guy measured the L-Pad as 100 Omhs, not sure I understand this one.

What do you think?

My speaker custom box is 19 inches wide, 31 inches height and 16 and a half inches deep. There's a bass port on the bottom.

It looks the previous owner followed some build instructions for speaker enclosures of this type.

Bob Crites already gave the advice to go with the only available web schematic but I look for your knowledge too.

Thanks.

Patrice
 
Not certain what happened with this project the OP had, but, just for info, I just grabbed a pair of TW-35 + CR-35 crossovers in a pretty terrible DIY jobs, that were mated with RSC 8'' fullrange units. The CR-35 I have only appear to be 6dB/oct, both on the LF and HF tap, plus an L-pad in there, no tar. I don't know if it's original.

I have not checked what value components are in there. The capacitor seems to be some kind of film. Will report when I've checked them out more.

Not much info out there on TW-35; I guess it's pretty close to T-35 overall?

az
 
Could you tell me what are the values as I understand you succeeded to open them...?

Let me guess: 2.8 mfd and 0.37mH

I tried without success to open the second set I bought. I didn't want to break them I must admit...

I'll probably use them as is in a speaker project I have for the summer vacations: two Jensen 12 inches with two Magnavox horn tweeters.

Thanks.

Patrice
 
audiozaz said:
Not certain what happened with this project the OP had, but, just for info, I just grabbed a pair of TW-35 + CR-35 crossovers in a pretty terrible DIY jobs, that were mated with RSC 8'' fullrange units. The CR-35 I have only appear to be 6dB/oct, both on the LF and HF tap, plus an L-pad in there, no tar. I don't know if it's original.

I have not checked what value components are in there. The capacitor seems to be some kind of film. Will report when I've checked them out more.

Not much info out there on TW-35; I guess it's pretty close to T-35 overall?

az
Click to expand...

TW-35:

1082.jpg


T-35:

attachment.php


The magnet of the T-35 is obviously bigger.

Right now listening to the first pair installed in a good DIY job with SP12B's and TW-35's:
IMGP2211.jpg
 
I'll try and have some answers tomorow morning. :)

That black and silver T35 is the OEM version AFAIK, with stamped horn instead of cast like the EV branded ones.

az
 
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Here is my CR-35's innards:

attachment.php


I did not take anything out and can not readily check the value of the parts, but I tested the network with a 7.8 ohm resistor on the LF and HF taps:

CR-35, unit 'A':

HF: 0.5*Vin @ 5200Hz / 0.707*Vin @ 3500Hz

LF: 0.5*Vin @ 5700Hz / 0.707*Vin @ 6500Hz

CR-35, unit 'B':

HF: 0.5*Vin @ 4400Hz / 0.707*Vin @ 3300Hz

LF: 0.5*Vin @ 5500Hz / 0.707*Vin @ 6700Hz

From this, I estimate that the low-pass inductor must be approximately 0.22mH and the high-pass capacitor, approximately again, 4.7uF. (with somewhat drifted values here)

Thread detailing my TW-35 find:

http://www.audiokarma.org/forums/showthread.php?t=373749

az
 
You got those cans open?!

Not to hijack the thread, but do the X36 and X8 cans open up similarly? Been wanting to recap some from the '70s but couldn't figure out how to get inside...
 
audiozaz said:
Openin my CR-35 cans was as easy as pulling out the friction-held bottom caps.

az
Click to expand...

Trying right now with a flat screwdriver and it's a no-go for me...

I don't want to use an hammer. I'll need something really thin to pry the cover.
 
Patrice B said:
Trying right now with a flat screwdriver and it's a no-go for me...

I don't want to use an hammer. I'll need something really thin to pry the cover.
Click to expand...

Sounds like these were closed-up pretty hardcore. One of my CR-35 had even let go of it's bottom cap inside the speaker enclosure. Kinda two extremes here.

az
 
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