Ampex ATR-700

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jimfreschi

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Background: I have an Ampex ATR- 700 connected to a Tascam M-520 recording console (I know...it's really a Tascam).

The Ampex ATR -700 has only XLR inputs and outputs on the rear of the deck. It also has 2 1/4 inchs female jacks which I don't use and I'm not sure what they are for. The outputs on the console are low impedance balanced outputs which are either +4 or + 8 dbm (I'm not sure which because the switch for these setting is inside the board and I've not checked them).

I have recorded and played back successfully using the tape deck and the board but since I do not have the manual, I wanted to get confirmation on a few things and therefore I have the following questions regarding the Ampex ATR -700 open reel tape deck:

1. Should I have the EQ switch set on NAB or IEC?

2. There are 2 switches on back, one for "A" and "B." Should these be set on "mic" or "line?" I have them set on "line."

3. For each channel there is a microphone attenuation switch which can be set to either 0 or 20 - which is the best setting for me? I have them set on zero.

4. On top of the cover for the head/transport are switches for "repro" or "sync."
Which is the best setting? I have them set on "repro."

5. There is are what I believe to be record level input knobs A & B for each of the two channels (a total of 4 knobs). If I only have cables connoted to inputs A of each channel, should I have the knob B turned all the way to "zero" or does it matter? I have them all set in the middle.

6. There are switches that allow for three settings 1,2 & 3 for "Record EQ," "Record Bias," and "Record Level." Don't know which of the three is best for my purposes.
I've been using the number 1 setting.

7. There are two knobs which seem to control output from the deck for each channel but they are labeled CH A and CH B. Why are they not labeled CH 1 and CH 2?
 
As for a free manual.... I paid $75 for mine. They are sometimes a rare thing. If you are lucky you might find a copy.

Answers:

1) NAB or IEC is up to you. In theory you get the same results with either but in reality they use different EQ so they will interact with the tape (slightly) differently. Try both and select the one that sounds best to you. I use IEC unless I need to send a tape to an NAB only machine.

2,3) One of the selling points of this machine was that it included an internal 2 channel mixer. Channel 1 has an A input and a B input and Channel 2 has the same. Thus you can take 4 inputs and mix them down to 2 tracks in the field. There are 2 inputs per channel that can be set for line level (-10 dB unbalanced), mic level (-70 dB) or mic with -20 att (-50 dB). You should set it for line level (you are not using mics). In line level the mic att does not matter. (another option if you want to use the balanced inputs is to select mic input with the 20 dB att on and see what your noise level is like This will go through the input transformers.)

4) The repo/sync switch selects which head is sending the signal to the output. You should select repro.

5) You should turn the unused input level to zero so as to minimize any noise from that input amp. In addition you should adjust the level of the (A) input knob that you are using so that 0 VU on your M520 reads 0 VU on the deck. ( it is a bit more complex than this....)

6) The record bias/EQ switches are set (in a properly calibrated deck) so that:

Rec EQ 3 3M250
Rec EQ 2 Ampex 406
Rec EQ 1 Ampex 456

Rec Bias 3 3M250
Rec Bias 2 456/406
Rec Bias 1 Ampex 641

Rec level 3 +6 dB (370 nWb/m)
Rec level 2 +3 dB (250 nWb/m)
Rec level 1 0 dB (185 nWb/m)

7) The left knob is the master record level control. It adjusts all mic and line input levels during record and has no effect during playback. The right knob is the output level control and adjusts the output level to the output connectors. It should be set so that a MRL recorded at 0 VU (as shown on your decks meters) gives 0 VU on whatever you are feeding the decks signal to.

The left channel is channel 1 the right channel is channel 2. Each channel has an A input and a B input to the internal mixer. The 2 left most knobs are for channel 1 input levels A and B (input A1 and B1 mixed to channel 1). The middle 2 knobs are the same for channel 2. (input A2 and B2 mixed to channel 2). The rightmost 2 knobs are the master record and output levels. These are dual knobs with an inner and an outer ring controlling channel and 2 as one.

Hope that helps.

--Ethan
 
It should be noted that the ATR-700 is a pin 3 hot machine. You might be better off taking the -10 dBv outputs from your M520 RCA connectors (don't use the balanced amp on the m520) and run them into the ATR-700 set in line in mode. The XLR to RCA cable should have XLR pin 2 go to the RCA ground, XLR pin3 to RCA hot. This will more closely match your signal levels. THe M-520 is -10 dBv (0 dB is 1 volt) and the Atr-700 is -10 dB where 0 dB is 0.775 volt.

Ethan

PS got any spare parts?
 
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