Revox Straight Line Turntables


Does anyone know whether the Revox H-9, B-297, etc. have a built in phone preamp and if so, whether and how it can be disconnected?

mohaveblues

AS Eric said, its very unlikely. Certainly the flagship product that i recall from the period did not.  I'm nto even sure why you ask.  But some model might have.

In any event, it realyl doesn't matter.  Bypassing an internal Phono stage is pretty simple. 4 wires MUST come out of the cartridge. run them wherever you like.

 

The linear tracking turntable was an interesting effort to eliminate tracking angle distortion. Note that in a normal arm, the angle is correct in only two places mathematically.  LT "fixes" this, but at the cost of a very complex anti-skate problem: "how do you keep equal tracking force on each side of the groove wall?"  As i recall, the answer was "not very well".

Quite a nicely made novelty anyway

 

The Technics SL10 I had 'when' came with a MC cart that had an onboard pre-amp for it, but also had a MC/MM switch at the back....along with an option of running on 12vdc....

One either likes tangentials...or not.
Given what it did then, for me, armed with a carbon brush and a really good antistat device....

I couldn't have done better at the time, and still dope slap self for letting it get away...

....and couldn't be beaten at making The Ritual easier.

@mohaveblues I think there’s a typo, the H 9 is mostly identical with the B 291 (not 297). My favourite was always the B 795, but couldn’t afford it back then ;-)

My instant reaction was that the B 291 doesn’t have ’a phone preamp’, in the sense of our usual RIAA preamps and such. Just looked up the Service Manual on Vinyl Engine. It confirms that the B 291 doesn’t have a ’typical’ phono preamp, yet there’s a section that talks about a preamplifier. It clarifies that the B 291 base model does have a linear MM amplifier, which works as an impedance converter. It can also been seen in the schematic. The manual explicitly states that the B 291 for this reason has been designed to work with MM cartridges (P Mount systems, the manual also includes a list of tested and recommended alternative cartridges).

In addition, an RIAA module was planned that, according to the manual, could be plugged onto the PCB. The manual also explains how this activity is to be performed, but I’m not sure whether such a module ever was available (the schematic on that page in the manual is hand drawn...)

So in short: yes the B291 does have a preamp section, but not a full one with RIAA EQ, unless the extra module has been added. To disconnect that, you need to locate the components on the PCB and bypass them somehow. A bit of a surgery, I suppose.

(Side remark: the service manual is in German, so I have translated that part. I’m German, but @tablejockey Revox isn’t, they’re Swiss 😉)

hifi engine is has a fantstic database. dunno if those tables are in there.