Looking for an old school Mentor re: Restoring Crossovers.

[DaleD]

I have custom designed speakers from 1979 that don't sound like they did originally and I'd like to restore them.
Ordinarily I wouldn't consider this but these are extremely special prototypes.

They were designed by Dean L. Weeks, an audiophile, perfectionist and genius. This is the man who designed boxes and crossovers for Ken Kreisels's original prototype subwoofers. Dean passed away in 1992, and there are no records of his designs.

The drivers are all in good condition, but I expect the values of electronic components in the crossovers has changed.
Can anyone mentor me through the process of evaluating the crossover, so I can replace each component. I would like to restore the entire crossover, but not change the design or sound of the original speakers.

Thanks I'm extremely grateful for all suggestions and assitance. I have a basic understanding of electronics, and soldering, but I'm colorblind/confused when it comes to "seeing" electronic value color coding accurately.

 

[KeepItSimpleStupid]

Capacitors may change over time. Capacitors should be marked with real values. The inductors generally won't change value unless a really bad thing happened to them.

Here https://www.parts-express.com/cat/crossover-components/21 is a good source for crossover parts.

 

[picbits]

As above - inductors will generally be good for longer than you will but the capacitors rapidly deteriorate. You need to make sure you replace them with the same value and type - if they are not polarised then you need to replace them with non-polarised and vice versa.

 

[tcmtech]

Given 34 years the range and sensitivity of you ears will have changed quite a bit too!

 

[alec_t]

I'm colorblind/confused when it comes to "seeing" electronic value color coding accurately.

I have difficulty too. A magnifier helps. Failing that, graphics processing software (e.g. Photoshop) often has a function for analysing the RGB content of an image.

 

[dr pepper]

Your speakers probably wont sound exactly the same, maybe similar, the speaker drivers surround and spider will have changed in that time, and the field density of the magnets and pole pieces.
If you can get the drivers thiele small parameters you can at least check the resonance of the bass drivers to see if they've changed, all you need is a variable freq signal source or maybe a test cd.

 

[large_ghostman]

also worth a google for old radio repair forums (i cant remember the names of any) there are some good ones where they get very excited about this sort thing! some of the lengths they goto in restoring some of the old audio stuff is mind bending!

 

[dr pepper]

I've had some not so good experiences with old radio forums.

Heres a good one though:

https://antiqueradios.com/forums/index.php

 

[eTech]

I have custom designed speakers from 1979 that don't sound like they did originally and I'd like to restore them.
Ordinarily I wouldn't consider this but these are extremely special prototypes.

They were designed by Dean L. Weeks, an audiophile, perfectionist and genius. This is the man who designed boxes and crossovers for Ken Kreisels's original prototype subwoofers. Dean passed away in 1992, and there are no records of his designs.

The drivers are all in good condition, but I expect the values of electronic components in the crossovers has changed.
Can anyone mentor me through the process of evaluating the crossover, so I can replace each component. I would like to restore the entire crossover, but not change the design or sound of the original speakers.

Thanks I'm extremely grateful for all suggestions and assitance. I have a basic understanding of electronics, and soldering, but I'm colorblind/confused when it comes to "seeing" electronic value color coding accurately.

Hi

Try creating a wiring diagram, whether the crossover is hand wired or on a pcb, by tracing the connections and drawing on a sheet of paper. Then try to determine the component values, and part numbers. If you can at least get the component values and interconnections you should be able to create a schematic/simulation model to get an idea of the crossover's frequency response characteristics. This will help is choosing part substitutions.

Regarding color values...it's probably not your eyesight...manufactures sometimes do a poor job of choosing color mixes for marking the parts...sometimes hard to distinguish between black and brown, green and blue, etc. You could measure each component value and deduce from the marking and the measurement what the part value might be.

Is it an active crossover or passive crossover?

Also, posting photos of the crossover and components might help..

eT

 

[OlPhart]

Howdy, First up, I suspect you want to restore the overall quality of the product. Therefore "restoring" the crossover isn't exactly right, since any driver changes will have different characteristics, and change crossover as well.
This one's tough, because to really do the speaker justice, it needs to be "re-tuned". To me that entails a Good microphone & quiet (anechoic) box and frequency generator w/clean amplifier to build a closed loop system for evaluating response.

I'll leave this as is, since I'm prospecting driver changes based on age, an assumption that may not be valid... G.H. <<<)))

 

[4pyros]

Well to fully restore you would need new drivers, new caps in the cross over, and maybe new dampening material inside the box.

 

[ghostman11]

As for the mentor part i would join a local Ham radio club, if there isnt one in the club i bet it wont take long to find one on air