Reel Tape Head Stage vs Phono Stage

I've recently bought a Technics reel to reel deck and have been thinking about getting an outboard preamp for it. Most of them are quite pricey, though, and there don't seem to be any kits around. (Bottlehead used to make one.) If I'm wrong about that, and someone can point me at one, I'd appreciate it.

Anyway, my question is about the difference between a preamp for a reel to reel and a phono preamp. The deHavilland tape head has 52dB gain, which, I see, is about the same as a phono stage. Now, I'm guessing that you can't just use a phono state as a tape head. Can someone tell me why not? Impedence matching or something of the sort? Is there any way to compensate for that?
What model Technics?
If it's an RS-1500US, I wouldn't suggest messing with it, it's got a highly accurate preamp system already.
I recently overhauled one for my neighbor - it's a beautiful machine.
Just needed some attention to bring it up to professional studio standards.
Yes, that's the model. It was recently restored, and they replaced any parts that seemed to need it.

My thought was to have a direct tape output added, so that one could choose between the internal and external preamps. But maybe it's not worth doing. It does sound quite good as is.
You are right in that phono and tape head preamps have similar amounts of gain but both have very different equalisation. A phono amp follows the RIAA curve for vinyl records where a tape amp needs to correct for the head characteristics, the tape type and the speed of the tape. Even though some controls such as speed may seem purely mechanical they will operate a switch to change eq as speed is changed. It would be quite a task to build an external amp.
Yes, that's the model. It was recently restored, and they replaced any parts that seemed to need it.

My thought was to have a direct tape output added, so that one could choose between the internal and external preamps. But maybe it's not worth doing. It does sound quite good as is.
The complex internal heads/preamp connections of that RS-1500US include complicated switching along with precise preamplification, and as I remember, are highly involved and difficult to even get to.
My advice, leave it alone, and avoid opening up a rats nest of problems, Technics knew what they were doing with that machine.
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Ask @kevinkr He builds very nice tape head preamps and might have some pointers. But as WOT points out, getting in there and adding a switch and extra wiring might be risky.
Pano, the Technics RS-1500US is an extrordinary (and extremely complex) machine, and the servicing and overhaul that I performed on my neighbors deck had to be done with absolutely perfect, no messing around, and By The Book accuracy.
In fact, the Technics Service manual is two seperate books.... literally books!
One for the mechanism procedures, 42 pages, the other for the electronics + calibration procedure, 91 pages.
It's not for just anyone to go poking around in, and few experienced techs even want to take on that job.
I cannot stress it enough.

If its been recently restored professionally, as was mentioned, I stand by my earlier statement to just leave it alone.
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I downloaded the service manuals for reference and, yes, they're astonishing!
Honestly, it's a great sounding machine, so maybe it is best to leave it as it is. I'm really excited to hear it with the new 15ips Coltrane tapes. I've got those, but no take up reel! That's on the way....
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The RS-1500 is a very nice NAB only machine that supports speeds to 15ips. If you are contemplating using it to play modern 15ips 2 track recordings you may need an external tape pre-amp because many of these tapes are recorded using IEC EQ which is not similar to NAB 7.5/15ips playback EQ. (Edit: Some sellers do offer options for either NAB or IEC EQ when you order.)

There is a NAB to IEC converter that plugs into the output of any deck that has an output impedance of 600 ohms or less, I don't know if that describes the RS-1500, but it does not strike me as an ideal solution.

Presumably from what you have said your machine is not an RS-1520.

The RS-1500 has an exceptional transport, and the heads are OK, the general consensus in the tape world is it's not ideal for playing studio master quality tapes regardless of EQ used without an outboard tape pre-amp.

I have designed several IEC only, and several NAB/IEC tape amplifiers. I had originally hoped to find a small market for these designs, but found the level of interest underwhelming both here and elsewhere.

Here is a simple one:

My go to is a Studer A810, and I have two MX-50 (not 5050) which I have used in tape amp development work.

My general feeling is that R2R tape is obsolete, and the price of admission is very steep for what you get in return. I've owned a total of six R2R excluding the Oki Denki I had as a teen. Have a modest collection of very expensive recordings, most of which IMO are not worth what I paid for them.

This is the best sounding recording I own, and the performance and music is notable unlike so much of the audiophile stuff out there these days. Only IEC though:

I will admit that I like to make 15ips and 30ips "mix tapes" direct from my DAC to the A810. (My system is mostly balanced I/O) They are almost indistinguishable from the DAC.
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I mostly bought this thing so I could try out those Ultra Tape recordings, specifically the new Coltrane ones. Very, very expensive, obviously, so I'll be interested to see how they compare to good vinyl pressings. It's possible this will be a shortlived experiment, and that I'll soon be looking to recoup as much of the investment as I can....
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