Microlimiter mods?????

[JASIII]

Anybody come across any mods for the alesis microlimiter to make it less noisy? I love the thing but DAMN, it's got some noise!

[toothpastefordinner]

replace the op-amps with low-noise op-amps

get the burr-brown replacements for the TL072s/TL074s/4558s/etc that those old alesis boxes are full of.

[Everybody's X]

sweet, Ill have to try that I got two of them sitting around

[JASIII]

replace the op-amps with low-noise op-amps

get the burr-brown replacements for the TL072s/TL074s/4558s/etc that those old alesis boxes are full of.

do you happen to know if those are socketed or soldered?

[Milkmansound]

probably soldered - but put in sockets when you replace them. Use solder wick to get out the ICs - you can let them heat up - they are worthless anyway! otherwise would you replace them?

other things to check into are the usual alesis mods... rectifiers, component upgrades, IC's caps... power supply!

I am sure you can find a schematic online - or at least get the data sheets for the IC's to make sure your new ones will be compatible.

[soundguy]

if you are gonna replace them, cut them out with clippers and then desolder the cut off leads that are left in the PCB, will be much easier to get out than trying to desolder the entire opamp unless you have a fancy desoldering tool. Cut them out, put a needle nose on the component side where the clipped off lead is, heat the other side of the pad with your iron and the leg will come right out easy peasy.

dave

[Family Hoof]

I love the thing but DAMN, it's got some noise!

No IC op amp I can think of will ever be as noisy as you're hinting at unless the designer has done something seriously wrong or it's just plain broken. Noise in older gear is usually caused by malfunctioning power supplies + worn out filter capacitors, and noise in all gear may also be caused by shitty grounding and shielding - but that's a discussion for another day. Being completely unfamiliar with this circuit, my generalized recommendation would be this... Find and remove all of the electrolytic capacitors (the polarized aluminum can type ones with plastic jacket around them), especially the ones that connect from the power supply rail to ground, and the ones in the power supply itself. Replace them with high quality, low impedance caps (i.e. Nichicon HE series, like the kind used for switching power supplies) of an equal or greater value, preferably much greater if they'll physically fit. To go one step further in reducing HF noise, you can "bypass" the larger electrolytic caps, that is solder a small poly cap i.e. 0.01uF across their leads.

Power supplies are important because its what the circuit uses to create a processed copy of your original signal. Noisy power supply means noisy audio. The caps in the power supply and the ones decoupling it at the circuit (from DC rail to ground) are there to filter out noise. If they;re old, dried out, or too small in value, then they won't be doing their job.

[jspartz]

I just ran across this post and I was wondering if anyone did the opamp upgrade? If so, what do you think? Also can anyone tell me if tip is positive or negative on the 1/8" power supply input?

I picked one up but I need to get it powered first. It did not come with a wall wart so I swung by the shack.

Thanks,

Jason

[Rodgre]

can anyone tell me if tip is positive or negative on the 1/8" power supply input?

It's neither.... it requires 9v AC not DC. I don't know is RS will carry an AC wall-wart.

Roger

[Everybody's X]

you can order them directly from Alesis