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Author Topic: I just bought a Studer A807  (Read 5454 times)

Offline esb1954

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I just bought a Studer A807
« on: April 15, 2010, 04:52:17 AM »
Are there any other Studer A807 owners here that have played Tape Project tapes on one with both stock electronics and then direct tape head out?  If you did the mod, how hard was it to do and how did you do it?  Any information will be greatly appreciated. 
Mike Sheehy

Offline Ki Choi

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Re: I just bought a Studer A807
« Reply #1 on: April 15, 2010, 11:53:16 AM »
Hi Mike:

Congratulations on your A807 acquisition!

Although I have two A807s but had not modified them.  The A807s may be easier in some ways and difficult in other ways to have direct head out.  The A810s and A820s have Pre-preamp assembly as a part of the headblock making it easier to access the head wires.  On the other hand, the A807's repro head wires out to a DB25 connector so you would need to change the wiring within the deck.  You would not need to change anything in the headblock and make the mod at the female side of the DB25 connector under the headblock. 

You should review Doc B's ealier posts on his first hand experience with the noise management challenge for the A810 direct head mod project he had done.
Ki Choi

Offline esb1954

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Re: I just bought a Studer A807
« Reply #2 on: April 29, 2010, 01:17:18 PM »
Ki,

Maybe Steve is explaining it to me in laymans terms, since I have no electronics back ground.  All that I can tell is that there are two sets of three wires that come from the preamp and connect to each of the audio cards.  I am trying to come up with a simple way to by pass the audiocard and come off of the heads  (sort of) without having to ship the unit out.  Do you think that smaller card with the pot to decrease the db level from the preamp would work?  That way all wires with there connecters could be hooked to this card.  No wires would have to added and routed. 

Thanks

Mike
Mike Sheehy

Offline Ki Choi

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Re: I just bought a Studer A807
« Reply #3 on: April 29, 2010, 02:26:44 PM »
Hi Mike:

I had a chance to take a closer look at the headblock area schematics of the A807 Mk I and II.  It turns out both versions use the same Repro preamp (1.727.430), and it would have two sets of (beige shielded) cables going to the audio board.  However, the Repro preamp is connected to the repro head by what it looks like to be a ribbon connector (to be confirmed when I look under the actual headblock) at the preamp circuit board and terminated into a female DB25 subminiature connector to be mated with the head wiring.

As far as I know, the A807 repro head has about 200mH of inductance and would work directly with a seduction tape preamp although controlling hum and other noise will be a challenge.  Again, I have not tried the direct wiring of an A807 first hand yet.  But I did help a friend wire out a head with 200mH inducance and used the Seduction as a preamp to adjust tape head azimuth and played some tapes with good results.

Ki
Ki Choi