Thanks for bringing up this topic as I'm currently designing a
restoration phono preamp for my own use. I'm doing this simply because
it's been awhile since I've built anything electronic or done any board
level work and I feel the need to scratch that itch.
I'm basically going to build in everything on your wish list except for
a couple of things:
Unbalanced (phono) inputs only The only reason I can see for balanced
inputs is for a line input to the EQ sections (an outboard option I
already have). Besides, to do this requires more amplifier stages (even
if unity gain) and I want to keep the active stages to a minimum.
The outputs will be both balanced and unbalanced.
<SNIP>”What I'd like to see built and marketed is a disk preamplifier
that does the initial impedence and capacitance match with the cartridge
and the first stage of amplification, then offers bridged output off
that stage, goes on to do a passive EQ with all the turnover and rolloff
options, and then an output stage. So, a person could play a disk once
(efficient workflow), make a flat transfer to a separate digital file,
and do the EQ to the best of their expertise and taste -- so there is
immediately a usable/listenable copy for researchers, library clients,
online, reissue or whatever. The idea of making two passes doesn't fit
budget-constrained workflows, and many of us are not at all sold on
digital EQ (which also takes extra time and extra steps after playback,
again inefficient). The device I describe offers the best of both worlds
-- you get that flat transfer to archive and do whatever in the digital
domain at some later time, but you end up with a listenable/usable sound
file at the same time.” <SNIP>
I plan on building my preamp as a dual-mono piece of gear with a
coupling switch that allows for an EQ'd and Flat transfer simultaneously
(or any combination thereof). Alternatively, it will have RIAA EQ
options and be able to be used as a stereo phono preamp.
By “passive EQ”, I presume you mean an RC network in front of an
I'm still on the fence regarding impedance/capacitance matching for my
own use because I only use the usual “standard” cartridges. It's an easy
Regarding your “Dream Preamp” comments:
If you want to keep the end result as clean and as “esoteric” as
possible (which I plan to do), you avoid things like VCA's, relays and
anything digital or even CMOS. It's only going to be hand operated, gold
contact switches and minimal amplifier stages.
That said, I'd like to see more opinions and wish list features
regarding this thread.
Corey Bailey Audio Engineering
On 4/11/2015 5:46 AM, Tom Fine wrote:
> Does anyone know of any reviews of this unit similar to Gary Galo's
> testing of the KAB preamp? Maybe that's fodder for an ARSC Journal
> article -- a testing and features shootout between this unit, KAB, the
> LOC Preamp and the TDL Restoration preamp. Maybe throw in an old
> McIntosh or Marantz for comparison.
> One thing I'd love to see on my "dream preamp" would be a
> digital-logic control panel for the EQ, rather than rotary switches or
> pushbuttons. I'd prefer the audio to be confined to a PC board, where
> all the EQ components could be laid out with short signal paths, with
> routing done by little micro-relays or whatever they're using these
> days. And of course separate controls for turnover and rolloff.
> Calibrated precision output levels may be useful for some folks. I
> notice that the unit Parker distributes has VCA controlled outputs,
> which is a good idea. Using a digital-logic user interface could
> accomplish this with VCA's.
> -- Tom Fine
> ----- Original Message ----- From: "Parker Dinkins"
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Saturday, April 11, 2015 8:19 AM
> Subject: [ARSCLIST] "Best of both worlds" disk preamplifier
>>> Date: Fri, 10 Apr 2015 08:00:14 -0400
>>> From: Tom Fine <[log in to unmask]>
>>> Subject: "Best of both worlds" disk preamplifier
>>> The device I describe offers the best
>>> of both worlds -- you get that flat transfer to archive and do
>>> whatever in the digital domain at
>>> some later time, but you end up with a listenable/usable sound file
>>> at the same time.
>> These preamplifiers have been available for some time:
>> Parker Dinkins