DIYbanter - View Single Post - is it worth it to replace caps in old equalizer??

Mogens V.

wrote:
On 24 Mar, 17:19, wrote:

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 ****ty.

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 ½ 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 ½ 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 ¼ 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

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.

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.