Topic: Marantz PMD661 mod - noise?

[Since85]

Hi,

Does anyone out there with a modded PMD661 see noise when the level is turned up all the way? Just recording "MIC IN", and the knob to "10" whether mics are plugged in or not. I would think that crowd noise would drown this out, but I am worried about quiet (solo acoustic, jazz) type recordings. MY ACM671 is dead silent when I do this, but with the 661 there is a bit of line noise. Is this normal behavior?

Thanks!

[tedyun]

Which mod do you have?

Hi,

Does anyone out there with a modded PMD661 see noise when the level is turned up all the way? Just recording "MIC IN", and the knob to "10" whether mics are plugged in or not. I would think that crowd noise would drown this out, but I am worried about quiet (solo acoustic, jazz) type recordings. MY ACM671 is dead silent when I do this, but with the 661 there is a bit of line noise. Is this normal behavior?

Thanks!

[Since85]

I am "beta testing" an ACM mod for the 661. I am wondering what the noise floor is like on other 661 decks.

[DSatz]

To judge the noise level of a preamp or recorder, its input must be shunted with an impedance similar to your microphones' output impedance (generally 150-200 Ohms or lower), and the gain must be set somewhere within the range that you would actually use for recording.

Never test the noise level of a preamp or recorder by turning up the gain all the way with nothing plugged in to the input. Doing so tells you essentially nothing because neither of the above conditions has been met.

When a mike input is left "open," the noise performance and RF immunity of the input circuit will generally be very poor, but not in a linear way (i.e. you can't even compare two recorders or preamps with one another this way). And "all the way up" isn't a known or standardized gain level, so again you can't even compare two recorders or preamps with one another that way. Whatever you hear or measure this way can easily lead to conclusions that are the opposite of the facts.

(Can you tell that I'd rather you didn't do things this way?)

--best regards

[Since85]

Thanks, I appreciate the advice.
 

[datbrad]

I am "beta testing" an ACM mod for the 661. I am wondering what the noise floor is like on other 661 decks.

I have a warm mod 661, and have never had a noise issue. I understand that the concert and warm mods reduce the preamp noise compared to the stock unit, but they are not as quiet as the super mod that is designed for nature/ambient recording.

Curious, what did Doug tell you he did to the one you havein order to call it an ACM mod?

[JasonSobel]

I am "beta testing" an ACM mod for the 661. I am wondering what the noise floor is like on other 661 decks.

I have a warm mod 661, and have never had a noise issue. I understand that the concert and warm mods reduce the preamp noise compared to the stock unit, but they are not as quiet as the super mod that is designed for nature/ambient recording.

Curious, what did Doug tell you he did to the one you havein order to call it an ACM mod?

right.  I have a concert mod PMD-661, and I've never heard any noise from the deck either.

and I'm also curious about the ACM mod to the PMD-661.  I wonder how the new "Advanced Concert Mod" differs from the regular "concert mod" that he's been offering for a couple of years now.