Thanks Adam. It is a good example of how a wish to simplify and make cheaper
go far off what is technically acceptable.
Klas.
At 06:09 2002-07-09 -0000, you wrote:
>--- In Klas Strandberg <> wrote:
>> What causes the noise??
>>
>> Klas.
>
>A 741 class op-amp, incorrect input impedance (for professional
>mics), and the balanced mic input stage being operated with no gain!
>When I mod it, I put in an AD OP275 op-amp, reduce the input
>impedance, give it plenty of gain, and run it to the level control.
>Plus put in caps that won't blow up if you attach a 48 volt supply
>that doesn't have its own blocking caps. What Marantz did is operate
>the XLR input stage with no gain so that they could run it through
>the filter and pad switches and then into the unbalanced mic pre!
>Crazy design in my opinion! Even after improving the circuit, the NF
>is still about 12dB due to limitations in the circuitry in the rest
>of the machine (for those who don't know, a good professional mic pre
>typically has a Noise Factor [or added noise] of 1dB or less).
>
>- Adam Liberman
>Liberman Sound
>www.libermansound.com
>
>
>>
>> >
>> >We service many Marantz recorders, and all the PMD222's that we
>have seen
>> >suffer from excessive noise on the XLR input. We offer an upgrade
>for those
>> >who are interested that reduces the noise by 10db (down to the
>level of the
>> >mini-jack input).
>> >
>> >Thanks,
>> >Adam Liberman
>> >Liberman Sound
>> >www.libermansound.com
>> >
>> This outgoing e-mail is scanned for viruses with Norton 2002
>>
>> Telinga Microphones, Botarbo,
>> S-748 96 Tobo, Sweden.
>> Phone & fax int + 295 310 01
>> email:
>>
>> org. no SE440130067001
>
>
>
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This outgoing e-mail is scanned for viruses with Norton 2002
Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email:
org. no SE440130067001
________________________________________________________________________
________________________________________________________________________
>From Tue Mar 8 18:22:32 2005
Message: 17
Date: Tue, 09 Jul 2002 06:09:05 -0000
From: "adam5532" <>
Subject: Re: Marantz PMD222 XLR Noise Problem
--- In Klas Strandberg <> wrote:
> What causes the noise??
>
> Klas.
A 741 class op-amp, incorrect input impedance (for professional
mics), and the balanced mic input stage being operated with no gain!
When I mod it, I put in an AD OP275 op-amp, reduce the input
impedance, give it plenty of gain, and run it to the level control.
Plus put in caps that won't blow up if you attach a 48 volt supply
that doesn't have its own blocking caps. What Marantz did is operate
the XLR input stage with no gain so that they could run it through
the filter and pad switches and then into the unbalanced mic pre!
Crazy design in my opinion! Even after improving the circuit, the NF
is still about 12dB due to limitations in the circuitry in the rest
of the machine (for those who don't know, a good professional mic pre
typically has a Noise Factor [or added noise] of 1dB or less).
- Adam Liberman
Liberman Sound
www.libermansound.com
>
> >
> >We service many Marantz recorders, and all the PMD222's that we
have seen
> >suffer from excessive noise on the XLR input. We offer an upgrade
for those
> >who are interested that reduces the noise by 10db (down to the
level of the
> >mini-jack input).
> >
> >Thanks,
> >Adam Liberman
> >Liberman Sound
> >www.libermansound.com
> >
> This outgoing e-mail is scanned for viruses with Norton 2002
>
> Telinga Microphones, Botarbo,
> S-748 96 Tobo, Sweden.
> Phone & fax int + 295 310 01
> email:
>
> org. no SE440130067001
________________________________________________________________________
________________________________________________________________________
|