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Author Topic: Ampex ATR-700 Questions  (Read 7033 times)

Offline commonman

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Ampex ATR-700 Questions
« on: January 09, 2011, 10:56:32 PM »
I have been unable to find a manual for my Ampex ATR-700 and need some help.

Background:  I have an Ampex ATR- 700 connected to a Tascam M-520 recording console.  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?

Jim Freschi

Offline ironbut

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Re: Ampex ATR-700 Questions
« Reply #1 on: January 10, 2011, 03:13:47 AM »
Hi commonman, (btw, we use our real names on this forum, you can add it to your signature in the user control panel so it'll show up on all your posts)

I'm not sure about the 1/4" jacks but I'd assume that they're for dynamic mic inputs?

If you're using XLRs from your mixer and you aren't having to turn the recording levels way up or way down (pots are almost always more accurate away from the extremes) you should be good to go.

As far as NAB or IEC, that's kind of up to you. You should be able to get slightly better sound with IEC if each eq standard is equally well implemented but using IEC makes it difficult if your expect to hand the tapes over to anyone else to listen to. NAB has been the most used eq here in the US. Depending on how you're using the tape you might prefer the sound of one over the other.

When the heads are set to sync, the record head doubles as a playback head so you can overdub in sync (otherwise the distance between the record and repro head will cause a delay between the two). Fidelity wise, it's aways better to set that switch to repro.

Always turn down the levels of inputs that aren't being used. Even if there isn't any steady state noise that's being added to the signal, there's always the chance that some spurious noise could come from an unused input and there's just no reason to take that chance.

The record eq and bias is different for each brand/formula of tape. If you're using a current production tape for you recording, it would be best to take it to a tech to have a pair of these set to for the particular tape that you're going to be using. This will give you the best signal to noise ratio and dynamic headroom. If you haven't chosen a tape to use, the two brands in current production are RMGI and ATR Magnetics. Which brand you choose and which formula depends on your finances and needs. I avoid buying old tape on auction sites. Even if it's half the price of new tape, it's a toss of the coin if it's been correctly stored and even if it works OK today, it might not in a month or a year down the line.
I don't know the history of why stereo channels have almost aways been Channel A (left) and Channel B (right) but I've never seen it any other way on pro or semi pro gear. Maybe to keep from confusing it with tracks that are always numbered.

Back with the bias/eq settings, all of those can be adjusted so if you contact the last owner, see if he/she knows if the machine was biased for a particular tape at a particular setting. The factory setting for a very popular tape when this machine was new (Ampex 456) is EQ-1  Bias-2. Those are the settings I'd try first.
steve koto
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Offline GLouie

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Re: Ampex ATR-700 Questions
« Reply #2 on: January 10, 2011, 12:10:31 PM »

I have the manual here, so I will try to supplement Steve's good advice.

I haven't seen any 1/4 inch jacks on ATR700s other than the headphone jack, so those may be a retrofit.

1-EQ- I would say for playback, use the position that corresponds to the EQ the tape was recorded in. For recording, you may choose, but NAB is standard in the USA and IEC in Europe.
2-Since each channel (1&2) has 2 inputs (A&B), you select MIC or LINE depending on what you have plugged into the inputs. Selecting MIC for "A" means you may plug microphones directly into both the channel 1 & 2 "A" inputs. MIC input mode means about 40dB more gain than LINE input mode. I would leave them on LINE to keep noise at a minimum unless you specifically want to plug a mike in. No phantom power is provided for condensor mikes that require it.
3-Mic ATT - If you do use the MIC modes, set the attenuator switches depending upon how much output signal the mike provides and how loud the sound is that you are recording, such that the loudest signal does not overload the ATR microphone preamplifier and cause clipping distortion.
4-Use REPRO mode unless you specifically are doing sel-sync work and need to monitor using the gap on the record head for playback. Fidelity is degraded when using the record head for playback, and is intended for real-time monitoring for doing overdubs.
5-I agree with Steve, leave all unused inputs knobs all the way down.
6- Factory setting for these switches are:

REC EQ 1 - Ampex 456/641 tape
           2 - Ampex 406
           3 - 3M 250

REC BIAS 1 - Ampex 641
              2 - Ampex 456/406
              3 - 3M 250

REC LEVEL 1 - Ampex level, 185 nWb/m
                2 - plus 3 dB (250 nWb/m)
                3 - plus 6dB (370 nWb/m)
(I think this just changes the meter zero)

None of these tapes are made anymore, so you really need to have the machine aligned for whatever tape you wish to use for recording. I would never accept these settings even for the indicated tape without testing. These settings are not used for playback (except the REC LEVEL which I think changes the meter zero setting).

7- the only output level knob I know of is the concentric knob on the front panel lower right. Mine are all labeled clearly as OUTPUT - ch1-ch2.  If you have additional A-B output knobs, these may be a retrofit. Or maybe early models had different labels. Otherwise, you are right, Ampex was calling the recording tracks 1-2 and the inputs A/B.

My notes indicate that this deck's polarity is pin 3 high on the XLR connectors whereas pin 2 high is now standard. However my notes also indicate that polarity is preserved on reproduce, but inverted on the LINE inputs. If correct, this infers that the LINE inputs will actually have correct polarity when fed from a contemporary pin 2 high device, but should have inverted repro polarity with pin 2 high devices. The outputs are on transformers so a mod should be easy if needed. I can't recall my method for determining this, so might be taken with a grain of salt.

Photos of the front/back panels might help determine if you have custom retrofits.


I have been unable to find a manual for my Ampex ATR-700 and need some help.

Background:  I have an Ampex ATR- 700 connected to a Tascam M-520 recording console.  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?


Gary Louie
Seattle

Offline commonman

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Re: Ampex ATR-700 Questions
« Reply #3 on: January 16, 2011, 04:54:07 PM »
Ironbut:  THANKS!  Yes, ok. I updated my profile and have put in my name and photo in the signature.  Thanks for the info.
Jim Freschi

Offline commonman

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Re: Ampex ATR-700 Questions
« Reply #4 on: January 16, 2011, 04:56:36 PM »
Glouie:  Thanks!  I like the detailed info on the record level and bias settings.  Terrific!
Regarding the 1/4 inch jacks, they are on the lower left hand side on the back.  There are 2.
Yes, maybe they are a retro-fit. 
I'm using the XLRs for input and output so, I suppose I can ignore those but I was just curious.
Jim Freschi

Offline Ken Roach

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Re: Ampex ATR-700 Questions
« Reply #5 on: January 16, 2011, 10:37:28 PM »
You can download an ATR-700 manual here..:
http://www.ilk.org/~ppk/Manuals/