my orban 642b eq hisses too much, fixable?

E

earworm

New member
well half a year ago i bought an orban 642b parametric eq,
i like the way it works but it just hisses too much, and its not just high frequencies, highcuts don't solve the problem, seems like its in the entire audio spectrum.

its an old unit of course so maybe some components on the inside had their time. Any idea what parts might be damaged, and is this something that can be fixed? I'm not planning to open it up myself, but there might be people out there that fix audio equipment.

all info is welcome!

cheers
 
orban was always a top notch co... found them alot in the install and radio markets... can't offer any specifics on this problem other that to start with rebuilding powere supply and perhaps replacing some electrolytic caps... would be worth it to me...
 
Ahhh... The 642B... It should be relatively quiet - If it's the black-faced model, it should be crazy-quiet. It's also relatively "tech friendly" to the average electronics service technician (from what I'm told from the guy who used to clean my gear - including my old 642B black-face).
 
Sounds like capacitors that have aged out of spec..posting a sound sample would help..it may be in the power supply or the filter section..or both..

Cheers,
Ray
 
its the black face, this weekend (i i wont forget) i'll record and upload some sound samples, what would be the best,
just recording the hiss, unplugging a cable to compare the hiss witht the silence of my soundcard..

last weekend i recorded vocals and the noise is just terrible, you can hear it in the mix and i didn't use high volumes and only tiny boosts

then comes the next question, any idea where i can find a decent technician in europe to fix it?

(and to keep on asking questions, i also have an Ashley sc66 (http://www.ashly.com/images/relics/lres/sc-66-ad.jpg) once again its got some basic hiss, not too much but i notice it clearly, anyone got the same unit and also hiss?
 
earworm said:
well half a year ago i bought an orban 642b parametric eq,
i like the way it works but it just hisses too much, and its not just high frequencies, highcuts don't solve the problem, seems like its in the entire audio spectrum.

its an old unit of course so maybe some components on the inside had their time. Any idea what parts might be damaged, and is this something that can be fixed? I'm not planning to open it up myself, but there might be people out there that fix audio equipment.

all info is welcome!

cheers
Click to expand...


hmm, that's odd. mine is excellent. granted i had it wired wrong for 6 months, but now it's wired correctly and i love it.

Are you sure you have it correctly wired?
 
I have a blueface model and it was completely recapped by the studio I bought it from..... but mine is DEAD quiet.

If you're hearing the hiss across the board you might look at the output wiring at the "block". Make sure the the output wiring isnt cracking or broken where it screws or is soldered into the unit. I am not sure if the black units are the same but mine has a "screw block" that the inputs and outputs attach to and the wiring is slightly exposed aat the block. If you've moved the units recently that could be an issue.

Bad (old) caps sounds more probable. The studio tech I taked to that I bought the unit from said it was fairly easy to recapp. Of couse easy is a realative term.




-mike
 
formerlyfzfile said:
I have a blueface model and it was completely recapped by the studio I bought it from..... but mine is DEAD quiet.

If you're hearing the hiss across the board you might look at the output wiring at the "block". Make sure the the output wiring isnt cracking or broken where it screws or is soldered into the unit. I am not sure if the black units are the same but mine has a "screw block" that the inputs and outputs attach to and the wiring is slightly exposed aat the block. If you've moved the units recently that could be an issue.

Bad (old) caps sounds more probable. The studio tech I taked to that I bought the unit from said it was fairly easy to recapp. Of couse easy is a realative term.




-mike
Click to expand...

mine is the single channel and i've replaced the opamps. i will probably recap it soon. but the opamps made a pleasant and noticeable difference
 
earworm said:
and its not just high frequencies, highcuts don't solve the problem, seems like its in the entire audio spectrum. cheers
Click to expand...

and there's your best indicator that it's a general systemic type problem like power supply filters and'or decoupling caps... anyhow gives ya chance to swap some op-amps while your in there...
 
dementedchord said:
and there's your best indicator that it's a general systemic type problem like power supply filters and'or decoupling caps... anyhow gives ya chance to swap some op-amps while your in there...
Click to expand...


hey demented, when recapping, if i source the same capacitance and voltage, making sure the cap materials are the same, there's no other catch to sourcing parts is there? Just look for high quality caps?

i've never done it so my orban will be the test
 
yeah that's it for the most part... sometimes you'll see some recommended for higher temp situations... which aint a bad idea say something about stabitlty... as for materiels if your looking at a bunch of mica's or something like that i'ld use polyproplene instead... BTW did you try the output thing for that hammond???
 
dementedchord said:
yeah that's it for the most part... sometimes you'll see some recommended for higher temp situations... which aint a bad idea say something about stabitlty... as for materiels if your looking at a bunch of mica's or something like that i'ld use polyproplene instead... BTW did you try the output thing for that hammond???
Click to expand...

actually, i hit a road block. i sent you a PM today regarding it.

I can't find the G-G terminals. I have a Hammond L100. spinet organ, not quite the same layout as the higher end models.

It has what i think are preamps for vibrato and one for percussion. These then proceed to the volume pedal, then to the amp on the lower section. The amp appears to hit the spring reverb in a loop, and then output to the speakers.

Not being able to identify which preamp to tap ( i assume it's the perc preamp as it's the second one in lline) when i open it up, i find two tag strips, neither have any marking on them.

i read that i could tap the signal from the speaker wires, providing a dead load, but now i can't find the schem for that configuration.

thanks in advance
 
what does a capacitor do?

and if the caps and opamps are replaced, will this change the sound of the unit? Are there standard brands that are good/or behringer-like? Can i just go buy me some caps and opamps and ask a guy who's good in soldering to replace them for me?

:rolleyes:
 
earworm said:
what does a capacitor do?

and if the caps and opamps are replaced, will this change the sound of the unit? Are there standard brands that are good/or behringer-like? Can i just go buy me some caps and opamps and ask a guy who's good in soldering to replace them for me?

:rolleyes:
Click to expand...
capacitors store electrical charge.

you would need to carefully source the correct capacitance and voltage of each cap in the device and purchase high quality caps. Texas Intruments and Burr Brown opamps are pretty good. What you'll need to do is to open the unit, find the model number on each of the opamps and cross reference them with newer models with either equal or better specs.

Then you can either find someone to remove and replace those components, or do what i did, learn how to do it yourself :) and here's the cliche "if i can do it, anyone can!"

it's intimidating, but if you research the basics it will make sense in a short amount of time.



no to hijack, but has anyone done a 3630 modification? Prodigy Pro has a mod that seems good. I've got all the parts accept single row 8 pin sockets. I cannot find single row 8 pin DIP sockets, and that's dumb because their just sockets!
 
OK, i'll start with opening the box and taking a look at it,
if i'm correct i still have the manual (with schematics)

i might try to replace the caps myself then, exiting!
But do you know places where they sell them? Of course i'm going to google (grin) but a hint is welcome.

i've heard of bruwn burr opamps before, but now how do i know what a high quality capacitor is (just look at the price?)
 
earworm said:
OK, i'll start with opening the box and taking a look at it,
if i'm correct i still have the manual (with schematics)

i might try to replace the caps myself then, exiting!
But do you know places where they sell them? Of course i'm going to google (grin) but a hint is welcome.

i've heard of bruwn burr opamps before, but now how do i know what a high quality capacitor is (just look at the price?)
Click to expand...


i get parts through mouser. they have this cool "project manager" thing that allows you to save parts lists based on a project name.

SO i have a bunch of project parts lists pending and i buy them when i start a new project.

mouser.com
 
earworm said:
what does a capacitor do?

and if the caps and opamps are replaced, will this change the sound of the unit? Are there standard brands that are good/or behringer-like? Can i just go buy me some caps and opamps and ask a guy who's good in soldering to replace them for me?

:rolleyes:
Click to expand...

Capacitors store electrical charge and in audio circuits are used to block DC current (hum) and bypass unwanted frequencies (like hiss, which is high freq white noise). If your bypass caps have dried up, they essentially either short or open. Bypass caps are designed so that at a certain frequency they start to lower impedance and flow the unwanted AC frequency to ground. If the bypass cap opens, the unwanted noise is simply passed through with the wanted signal. This is a waaaay watered down explanation BTW. Caps also are not capable of passing DC current and can only pass a *changing* current (like AC signals). Power supply bypass caps are usually responsable when you astart to get hum and low freq noise (usually line 50-60Hz).

The best caps to replace would be Panasonic 105C rated caps and the best place to get them is :http://www.digikey.com/

You can order off the site and they will fill any order from 1 part to 1000s.

Good Luck
 
brendandwyer said:
I've got all the parts accept single row 8 pin sockets. I cannot find single row 8 pin DIP sockets, and that's dumb because their just sockets!
Click to expand...

those would be SIP sockets... single inline ... which actually you dont want to use sockets for sips in particular... they tend not to hold tight... FWIW... other than durring experimental stages i dont use sockets at all... there's a thing called parasitic capacitence that can effect freq responce....

also when you upgade opamps sometimes you run into problems with the new stuff oscillating and such... the fix is to ad a cap between the power supply pins...(4-8)
 
dementedchord said:
those would be SIP sockets... single inline ... which actually you dont want to use sockets for sips in particular... they tend not to hold tight... FWIW... other than durring experimental stages i dont use sockets at all... there's a thing called parasitic capacitence that can effect freq responce....

also when you upgade opamps sometimes you run into problems with the new stuff oscillating and such... the fix is to ad a cap between the power supply pins...(4-8)
Click to expand...


i was wondering why the article called for sockets for the vca's. I didn't think vca's were something i'd be changing out all the time.

That's good. i'll just solder them directly.

Any luck with my hammond fiasco? :)
 
brendandwyer said:
.

Any luck with my hammond fiasco? :)
Click to expand...

went by the old shop and looked at the schemo... this one is'nt like i remember but it's still doable... trying to get someone to scan the schemo for me so i can send to you... there's a wire coming out of the expression pedal that should work fine... it's the white one...(assumming it's not been rewired)
 
You must log in or register to reply here.
Back
Top