is it worth it to replace caps in old equalizer??

Probably not. If it sounds OK with no signs of hum, then it's likely that the caps are still working up to spec. If you have access to an ESR meter, you could check them, or if not a meter, you could look at the ripple across them with a scope. I'm a great advocate of " if it ain't broke, don't fix it " - a philosophy that has served me well for 35 years in the business. Shotgun replacement of components, or replacing just for the " might be " hell of it, often results in problems that weren't there in the first place, in my experience. If they are really easy to get at, and you can get replacements with similar or better specs, and are determined to put your stamp on it, as it were, then go ahead and replace them. It won't do any harm.

Arfa

No.

It's not uncommon for electrolytic caps to last 40 years or longer. I have KLH table radios that are 45 years old, and still work with their original electrolytics.

Electrolytic caps are odd -- they aren't anywhere nearly as unreliable as you'd expect them to be.

No. If youre considering doing jobs that dont need doing it may be time to reevaluate ones life.

NT

Don't replace them till they need it. The old high voltage ones can last a long time, but if you've got a few spare minutes, some spare dollars, do it by all means. Dont worry about re evaluating your life. Life is full of cynics. You do right, its wrong you do wrong its still right etc . Its how you feel its your life...... PS Fixing things that dont need fixing is not good, only if youre there. Priority says fix things that you need that need fixing, or as a preventative. Most likely you'll drop the equipment of a truck first...or similar. Lifes like that....

If it ain't broke, don't fix it...

Especially if it is Realistic!

Probably not, since all the electrolytic coupling caps in there are bad too. And even if you do, you're stuck with 1970s Radio-Shack grade op-amp design.

--scott

--
"C'est un Nagra.  C'est suisse, et tres, tres precis."

I am an expert on audio, certain areas, and this is one of them.

I totally agree with those who say if it ain't broke don't fix it, but, some things are built broke.

To get the best quality integrated audio, which is the type of signal for which this EQ was designed, they chose the wrong frequncies.

Now replacing the power supply filters is probably useless because of the low current drain of the unit, there is simply almost no ripple current to "wear out" the capacitor. However there are other things one can do.

I have modified a couple of these, but then that was for integrated program material, if you use it on a guitar you might want to go a different direction. I don't remember the component values, but once you understand how it works you can do things, many things.

A buddy of mine had his speakers in the corners, which made them very boomy. They have bass, but it is shitty.

At the wiper of the 60Hz control there is a cap, a coil and a resistor. What I did was to take and change that control to about 35Hz and made it shelving, that is to extend the control's range all the way down, instead of that peaked response it originally had. I did this by taking the resistor value down to less than =BD the original and installing a capacitor about ten times the capacity of the original.

The 250Hz control was lowered to about 100Hz by cutting the resistor's value in about =BD and installing a capacitor about three times the original value.

The 1 Khz control was left alone. The 3.5 Khz control had it's range extended slightly downward by increasing the value of it's capacitor.

Finally the 10 Khz control was modified to be shelving, and it's range shifted upward. This brings out the timbre, rather than the tinny treble. This was accomplished by actually lowering the capacitor value as well as the resistor value, and shunting the coil with a low value resistor, about =BC the resistance of the new resistance value in the tuned circuit for that band.

Actually if you know how to futz with it, you could have a nice setup. run the channels in tandem but change some of the frequencies. Lower the low ones on the left and raise the high ones on the right. And if you tandem the channels you also can use a Y adapter to pick off the signal for another amp, between stages.

Tell you what, if you get a chance to play a guitar on two amps at once, enjoy. Set one clean and one fuzzed out. With a little adjusting and practice you can make it sound like you are playing two guitars.

JURB

As suggested elsewhere, the PSU caps seem to be ok. You might want to consider replalcing any electrolytics in the signal path though.

Graham

*After* replacing the caps !

Yes.

Graham

If youre going to muck with it then start with a 10 band or more, pointless to play with something as very limited as a 5 band.

If you wanted to adapt it for guitar use only, I'd make each side different freqs and you can feed the signal thru both sides to get a

10 bander. And refrequency the 1kHz slider, which is the least useful of them all.

But... its not worth bothering, might have been 25 yrs ago.

NT

If it sounds fine I wouldn't worry about it. On the other hand caps are cheap and replacement is easy.

Plus many/most inexpensive EQ's arent phase liniar anyways... Mostly useless for high quality audio. Besides, problems with a hifi setup is better addressed actually fixing those problems at the source, not trying to EQ them out.

--
Kind regards,
Mogens V.

And as Scott mentioned, it's based on quite old opamps. Not worth the efforts, not even if tone is under par. Then better go get a better one. Unless the OP prefers that killer vintage tone.

--
Kind regards,
Mogens V.

shack),

new

Actually I opened it hoping I could replace an op amp but there are no ICs in it at all. But I did eventually realize that the two big electrolytics are probably part of the power supply.

shack),

new

I appreciate your response as well, but the cirumstances are that I have some free time while I wait for some parts to arrive before I can get back to recording, and for the past few weeks I've been doing a lot of soldering. Since I've got all the tools laid out from the previous work, and can't get back to recording, I figured I'd open up anything I have around that is essentially worthless but still potentially useful (in my opinion) and see if I could do any worthwhile modifications (I was hoping I'd be able to replace an op amp in the equalizer, but there aren't any in it). However it does seem like my rudimentary self-learned knowledge of electronics has already caused me to do some useless things, such as replacing the op amps in an Alesis Microlimiter with ones with lower noise specs, hoping to get a lower noise floor, which did not happen because I didn't understand the circuit well enough to realize that swapping op amps wouldn't result in a quieter unit.

But unfortunately it appears I won't be able to try them. The plastic ends on the sliders don't come off the sliders, they're either glued on or were manufactured that way, so it is impossible to take off the front panel to get behind it where the circuit board is. Oh well.

If you had read my post accurately you would have noticed that I said I use the equalizer in a guitar effects chain, not to EQ a 'hifi setup'. I'm quite sure the quality is no worse than a typical cheap equalizer guitar pedal. The guitar signal goes through the effects chain, into the amplifier, and the amplifier is miked. So 'phase linearity' of the EQ isn't all that important, though I suppose it may color the effects in some way, which may be either good or bad, but I'd have no way of determining that without a 'phase linear' EQ to do an A-B comparison with. In any case, it's not something I'm concerned about as it sounds fine to me.