I'd be OK with analog/manual switches and knobs, but you'd have to go co$tly if you don't want them
to wear out. Figure this thing is not a set and forget device, people will be fiddling with the
controls every time they put on a disk. That's a lot of hard use in a production environment.
Also, I agree with Richard and Paul, that's the way to go with outputs. Richard's suggestion is
perfect, just throw a set of RCA-to-TS adapters in the box.
I don't think I included balanced inputs on my list, I agree with your point about them. I forgot if
it was in this context or another that I said just use Henry Matchboxes if it's that critical. The
only circumstance I can think of where it would be super-critical like that would be if you were
looping through something like an old Pultec that really wants to feed a 600-ohm balanced device.
----- Original Message -----
From: "Corey Bailey" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, April 11, 2015 3:53 PM
Subject: Re: [ARSCLIST] "Best of both worlds" disk preamplifier
> Hi Tom,
> 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.
> You wrote:
> <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 amplifier stage.
> 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 add-on though.
> 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
>>>> 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