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External Preamps with Zoom H4n Pro Recorders, Players & Tape Machines
Old 13th March 2018
  #1
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andersmv's Avatar
 

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External Preamps with Zoom H4n Pro

Does anyone have experience running external preamps into Zoom recorders? In an effort to avoid lugging a Laptop and Apollo interface with me, I grabbed a Zoom H4n Pro. After talking to zoom about running an AEA TRP preamp into the Zoom, they said it would be fine and to just set the Zoom preamps to their lowest setting when going in. I figured it shouldn't be much of an issue.

The TRP has LED's on the front to help out, it's only a 3 light LED but it's better than nothing. Feeding into the zoom, I had the levels on the TRP set pretty low, I set the Zoom preamp on 0.1 (the lowest it would go as suggested by Zoom) and the peaks were sitting around -12 on the Zoom meter. Listening back on the headphones though, I could hear some pretty clear and obvious distortion. I ended up having to turn the Zoom preamp up to 0.4 and turn the TRP preamp down a bit, that seemed to make it happy but bugged the crap out of me...

The next day, I decided to set up a signal generator in my DAW and send it some test tones to try and figure out the best level for the Zoom preamps. I started out sending the test signal through my TRP preamp and back into my DAW so I could match them and make sure the preamp was sending at the same level the DAW was outputting (Basically trying to calibrate the TRP to the Zoom). Once the TRP was set correctly, I plugged it into the Zoom and matched the levels in the recorder's meter.

To save some time, I went back and forth and was getting some pretty inconsistent results. As soon as I was getting stuff calibrated with the test tones, I would try and record something with a mic and get audible distortion even though the Zoom was showing ample headroom. Am I missing something, or are the Zoom's just crap? I've used them a lot in the past, but never like this with external preamps. Kind of disappointed....

My compromise was to mess with the Zoom level until I got to a point where the Zoom metering was actually visually reflecting audible peaks. I'm still feeling pretty uncomfortable about the whole thing and considering just bringing the computer down there anyway and returning the Zoom...

Clips below if anyones curious, they aren't very helpful though...
Attached Files
Old 13th March 2018
  #2
Gear Nut
Hi Andersmv,

I've done a similar task with the tascam dr100; r88 to trp to tascam. It worked just fine, levels were clear ect. I suspect that the big difference here is that the tascam has a line in switch, so I wasn't using double mic pres.

As an added note: Since getting the SD mixpre-6, I'll never go back. If you can return the Zoom....
Old 13th March 2018
  #3
Without wishing to muddy the waters, I will add that I have successfully done what you are describing, feeding a Sound Devices USBPre2 with an external preamp. With the USBPre's inputs all the way down, the line level signal was received with minimal coloration/distortion. Certainly this basic approach should not cause a problem, depending on the specific equipment used...
Old 13th March 2018
  #4
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Ya, I've had a lot of experience in the past with Sound Devices stuff for mobile work. This is literally for one quick job, so I thought I could get away with just grabbing a Zoom for cheap. I've used zoom stuff a lot as well, but never for something like this. I didn't think it would end up being this much of a hassle for something so simple... I'll probably end up returning the Zoom, I'm still frustrated that it's giving me so many problems, how hard is it to give you either line level or a way to bypass the preamps and go strait to the converters?
Old 13th March 2018
  #5
Gear Maniac
 

Quote:
Originally Posted by andersmv View Post
After talking to zoom about running an AEA TRP preamp into the Zoom, they said it would be fine and to just set the Zoom preamps to their lowest setting when going in. I figured it shouldn't be much of an issue.

I would try and record something with a mic and get audible distortion even though the Zoom was showing ample headroom. Am I missing something, or are the Zoom's just crap? I've used them a lot in the past, but never like this with external preamps. Kind of disappointed....

My compromise was to mess with the Zoom level until I got to a point where the Zoom metering was actually visually reflecting audible peaks. I'm still feeling pretty uncomfortable about the whole thing and considering just bringing the computer down there anyway and returning the Zoom...
Not surprising as the H4n Pro can only handle -6dBu max balanced and +2dBu max balanced input levels in 'line-level' mode. The resultant problems such as you are having are much reported. Not sure if you are using balanced on unbalanced connections, but a 20-30dB pad (perhaps more) should give a cheap solution. Alternatively, return as you propose and get a similarly-priced recorder that can cope with a proper line-level signal: e.g. Tascam DR60D or DR70D [line level nominal +4dBu, +24dBu max] or, handheld form factor, DR40 [line level nominal +4dBu, +20dBu max]. If you love Zoom (?!), then the H5 has a pad that allows +22dBu max.

Cheers,

Roland
Old 13th March 2018
  #6
Gear Maniac
 

Quote:
Originally Posted by VillageOp View Post
I suspect that the big difference here is that the tascam has a line in switch, so I wasn't using double mic pres.
Bypassing the mic pres isn't the particular issue here, and, of course, it is extremely unlikely that such a cheap recorder does in fact bypass the mic preamps: most such recorders simply pad the input level in line-level mode (which isn't a major issue). The Zoom H4n just does this inadequately.

Cheers,

Roland
Old 2nd April 2018
  #7
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Thread Starter
Below is a link with the audio I did with the R88 in the cave, if anyone is interested. The zoom ended up working fine, the technical details of how I had to set up the gain staging are still a mystery to me, but I made it work. I sent the Zoom back, if I end up doing more mobile stuff like this I'll just get something from Sound Devices or just put together a small mobile rack and bring a laptop into ProTools...

Caverns Promo.mp4 - Google Drive
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