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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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1st Apr 2019, 4:39 pm | #1 |
Tetrode
Join Date: Sep 2016
Location: Tring, Hertfordshire, UK.
Posts: 87
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Revox A700 Mic inputs
I have just purchased a Revox A700 Recorder and wish to use the Mic inputs.
These inputs fail to work with known good microphones. The previous owner said he never used these so not sure if they ever worked. I don’t have a user handbook but the circuit diagram indicates two mic transformer Interface boards. Were these boards an option or where they are located within the machine. Thanks for any help available |
1st Apr 2019, 10:35 pm | #2 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,969
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Re: Revox A700 Mic inputs
I think they were standard in the A700 but they are also "balanced" inputs as with XLR 3 pin connectors. The mic's output is connected to "tip" and "ring" on a stereo headphone jack plug. A mic with a normal tip and sleeve jack plug probably wont work. There may be nothing wrong with the mic input sockets and preamps.
To test with a standard unbalanced mic you could try temporarily bridging its sleeve and ring connections in the jack plug, or by making up an adaptor lead. Last edited by TIMTAPE; 1st Apr 2019 at 10:44 pm. |
1st Apr 2019, 10:45 pm | #3 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,866
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Re: Revox A700 Mic inputs
Don't unbalanced mikes on mono jack plugs short the ring contact to ground, providing continuity for an unbalanced signal on the tip?
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
1st Apr 2019, 10:48 pm | #4 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,969
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Re: Revox A700 Mic inputs
Good point David, they do. My apologies.
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1st Apr 2019, 11:08 pm | #5 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,223
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Re: Revox A700 Mic inputs
The amplification system for both Mic and Line is the same but with different gain set by feedback.
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2nd Apr 2019, 12:36 am | #6 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,866
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Re: Revox A700 Mic inputs
Could be just dirty sockets.
David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
2nd Apr 2019, 12:18 pm | #7 |
Tetrode
Join Date: Sep 2016
Location: Tring, Hertfordshire, UK.
Posts: 87
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Re: Revox A700 Mic inputs
I was using RTS jacks connected to 600 ohm AKG mics.
Cleaning sockets has now given me 3 out of 4 sockets working with possible intermittent master record level slider. 4th jack appears to be loose, perhaps joints on pcb fault. However still looking for user manual if available. Thanks for your help. |
2nd Apr 2019, 12:24 pm | #8 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Revox A700 Mic inputs
Revox A700 user manual is available on the vintageshifi site.
Lawrence. |