XLR into a Home Audio System

Hello everybody:

I'm looking for put a graphic equalizer between my CD player and the
amp. Specifically, I haven't yet decided between the dbx

As many of you shoul know such processors have only balanced XLR/TRS
connectors, nevertheless their manual claim to be able to handle
unbalanced connections.

Arny Krueger...

Not universally true. For example, some Rane graphic eqs have both pro and
RCA connectors.

Karl Uppiano...

Then there is no problem.

TimPerry...

look real close at the rear view. also see specs below and not 1/4" inputs
and outputs.

So far I understand that I can make my own balanced-to-unbalanced

Arny Krueger...

Please see for the usual reference in this area:

cables easily, and also, that it's better to use a transformer isolated

Arny Krueger...

In all liklihood - unecessary.

connection in my case.

Karl Uppiano...

Yes, and no. A high quality transformer would be expensive and unnecessary
unless you plan to string the cables a very long distance, which would be
why you might consider balanced lines in the first place. Lots of modern
balanced equipment doesn't use transformers these days anyway. They use
op-amps.

Nevertheless, I'm most concern about the impedance and input signal
compatibilities. As I understand impedance diferences between
equipments may lead to signal degradation, noise and in the worst case

Arny Krueger...

Shouldn't be a problem, as signal levels out of a CD player are typically
not all that dissimilar from pro audio conventions. Putting the eq in the
tape loop of a home system could be a different situation.

Arny Krueger...

No way!

to damage in the equipment.

Karl Uppiano...

Impedance should not be a concern. These days, output impedance is usually
low; input impedance is usually high - both for pro and consumer gear. Audio
lines are not transmission lines requiring matched impedance. Pro signal
levels are usually +4 or +8 dBm; consumer gear is sometimes -10 dBm. This is
not a big enough difference to cause damage, but pro gear might overload the
consumer gear. Similarly, the consumer gear might not have enough output to
drive the pro gear without a booster amplifier.

So I'm asking your kind help in order to find (or maybe build) the
equipment that shall connect both systems perfectly. I want the signal
to be perfect on, in order of preference, quality, impedance and
voltage.

What do I need for the job?

Arny Krueger...

Simple cables or adaptors.

Geoff...

First you need to rationalise why you feel a graphic EQ there at all. Then
I would be inclined to find a unit with the same type of inoputs/outputs as
the rest of your gear.

TimPerry...

four 1/4" to RCA adaptors or 1/4" to RCA cables

Specifications of CD player and amplifier input signal are:
Sensivity: 150 mV
Impedance: 50 kilohms
amp: S/N (78' IHF): 82 dB (A, 150mV(Weighted network, input level))

Arny Krueger...

These are for just the integrated amp, right?

Specs of the dbx 231 (and 1231) are:
Inputs
Connectors: 1/4" TRS, female XLR (pin 2 hot)
Type: Electronically balanced/unbalanced, RF filtered
Impedance: Balanced 40kohm, unbalanced 20kohm
Max Input Level: >+21dBu balanced or unbalanced
CMRR: >40dB, typically >55dB at 1kHz
Outputs
Connectors: 1/4" TRS, male XLR (pin 2 hot)
Type: Impedance-balanced/unbalanced, RF filtered
Impedance: Balanced 100ohm, unbalanced 50ohm
Max Output Level: >+21dBu balanced/unbalanced into 2kohm or
greater