Hi Tom,
With all due respect I'll suggest that you listen to similar
demonstrations before making assumptions about what other "are
enjoying". "Happier sonic results" is simply dismissive if not
insulting unless improved sound stage & more accurate presentation of
instrumental & vocal signatures is just the stuff of audiophools.
Cheers,
Duane Goldman
On Sep 9, 2009, at 5:36 AM, Tom Fine wrote:
> They make flat phono preamps. One of the online guys who sell DC7
> and DC8 software sells a battery-operated one. This amp is designed
> for 47k-ohms input impedence.
>
> I have tried de-curving both LP and 78 in the computer and not had
> results I enjoyed listening to. I prefer a high-quality preamp stage
> before A-D conversion. Like Lou said, it takes away a lot of
> guesswork.
>
> As for Duane's comment, I took that as confirmation that people in
> the "high end" are indeed using non-RIAA playback curves for some
> stereo-era disks and enjoying the results. I would suggest, again,
> that what they are enjoying is their own form of pre-set (and
> somewhat crude) "tone controls," remedying decisions they didn't
> find enjoyable in the recording or mastering stage. They are NOT
> playing back with the "proper" curve. The _standard_ curve in 1958
> and ever onward, since 1954 was the RIAA curve. So, I say again that
> their goal could probably be achieved with even happier sonic
> results using a professional-grade equalizers AFTER an RIAA phono
> preamp (which would thus neutralize the standard "encoding" and
> leave you with what the recording and mastering engineers felt you
> should hear -- you can then make your own adjustments to get to
> where you _want_ to hear it).
>
> As for using a professional mic preamp to send a non-equalized
> "flat" signal to a A-D converter, Richard is correct that one cannot
> get a typical mic preamp to have the proper input impedence UNLESS
> one changes the input transformer (assuming the unit has one). I
> think Jensen makes a transformer that will meet this requirement.
> Another less desireable solution that _might_ work is to wire an
> external mic transformer in reverse, so it "sees" somewhere around
> 1k-ohm and the cartridge "sees" something in the dozens or hundreds
> of k-ohms. I assume there would be a good bit of signal loss plus
> the distortions of adding another stage of transformer, so your
> overall results may not be happy.
>
> -- Tom Fine
>
> ----- Original Message ----- From: "Richard L. Hess" <[log in to unmask]
> >
> To: <[log in to unmask]>
> Sent: Wednesday, September 09, 2009 12:05 AM
> Subject: Re: [ARSCLIST] Non-RIAA curves for stereo LPs????
>
>
>> At 09:49 PM 2009-09-08, Andrew S. Hamilton wrote:
>>> The caveat is that the load seen by the cartridge needs to be what
>>> it expects to see when plugged into an appropriate de-emphasizing
>>> preamp, and mic preamps are typically very low impedance (far from
>>> the typical 47k Z that MM cartridges like to see). Analog
>>> networks can work, but only sound great when carefully trimmed to
>>> ideal value components. With dsp, the component trimming can be
>>> theoretically exact and won't drift over time.
>>>
>>> Still, I wanted to get the flattest possible transfer, and so I,
>>> instead, used a Great River MP2-MH mic pre (input Z ca. 1200
>>> Ohms?) to amplify the direct output of my tt and put a 47k Ohm
>>> load resistor across the hot and ground legs of each lead at the
>>> termination of the interconnect, as it enters the mic pre, with
>>> the intention of applying manual declick and digital de-RIAA after
>>> the transfer. The cartridge I am using is an Ortofon VMS 30 MKII,
>>> which accepts load impedances of 47k-100k, according to the .pdf.
>>
>> Hello, Andrew,
>>
>> Please forgive me if I am misunderstanding what you are
>> saying...but as I understand it, there is a fundamental issue with
>> your configuration.
>>
>> If the input impedance of preamp is 1200 ohms and you put a 47,000
>> ohm resistor in parallel with it, that brings the input impedance
>> down to 1170 ohms. Putting it in series loses a whole lot of signal
>> and destroys signal to noise ratio.
>>
>> You can't increase the input impedance by putting the desired
>> resistor across it if it's already too low. Parallel resistors are
>> 1/(1/r1+1/r2).
>>
>> The frequency response you describe is in keeping with too low a
>> load on the cartridge.
>>
>> Cheers,
>>
>> Richard
>>
>>
>> Richard L. Hess email: [log in to unmask]
>> Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
>> Detailed contact information: http://www.richardhess.com/tape/contact.htm
>> Quality tape transfers -- even from hard-to-play tapes.
>
H D Goldman Lagniappe Chemicals Ltd.
PO Box 37066 St. Louis, MO 63141 USA
v/f 314 205 1388 [log in to unmask]
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