What hardware needed for recording a lecture directly from the power amplifier?

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rix55

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Hi All, till now, being a moron, I have been recording lectures by crudely taping the earphone mic (the one that comes with mobile phones) near the microphone of the speaker and recording the audio through my phone by keeping it in front of the speaker.

I know that you can somehow record directly from the power amplifier... but, dunno what gear you need. There are line-outs for the amplifiers. What hardware device do I need to record from that line-out? I am sure that my mobile can't do that - tried it... recorded loud (very loud) noise (even though the speaker was speaking in a low voice, my mobile got it as though he was screaming at the top of his lungs)

By the way, it is line-out that you record from right? or is there some other thing in the amplifier for recording? Thanks a lot.
 
The line out is what you would normally use for recording.

But you will have difficulty if you want to connect directly from a line output to a microphone input, because the line-out is likely to overpower the input (as you've discovered).

What you need to make use of the line out is a device that has a line level input.

Consider getting something like the Zoom H1 handheld recorder. It has a line in, but you can also record using its own mikes.
 
So, with the Zoom H1, I will be able to underpower the recording from the amplifier? So, I just connect line out to the H1 and can underpower it and record the whole thing? Thanks, gecky zzed.
 
Can of many worms this.

Firstly, have we actually established the "power amplifier" HAS a line out? If so it will probably be a "pro" operating level of +4dBu, about a volt rms. I will check the line inputs on a Zoom Hx but I would guess they would be fine. Such a level might however be a bit hot for a PC input or a phone.

If there is no line out it is possible to buy a cheap "DI" box that can reduce even very high power amplifier speaker levels to line level. Behringer make one such. N very B! You must get a DI RATED for amplifier input! The standard fare can only cope with guitar levels and a bit more. (note too that such DIs MUST be used with a load. Not applicable in this case, jus' sayin')

But, some PA amplifiers use the "100 volt line" speaker distribution system and even the high level DI would probably overload on that setup. Find out. (point: For reasons I have never been able to discover, our US friends use a "70.7 volt" system? That would be almost as bad as the more mathematically easier 100V)

In any event be very careful tapping into speaker lines, you could damage the PA (and 100V will bite!)

Cannot find a line input sensitivity specc' but since line out is specc'ed at -10dBV (316mV) I suspect the H1 is geared for neg ten inputs? Overload from a +4dBu source is therefore a possibility.

Dave.
 
Maybe rix55 could state the manufacturer and model number for the power amplifier? Or at least a picture of the back of the unit (assuming that's where the "Line output" resides).
 
arcaxis said:
Maybe rix55 could state the manufacturer and model number for the power amplifier? Or at least a picture of the back of the unit (assuming that's where the "Line output" resides).
Click to expand...

Hi arcaxis & gecko, I have attached the PA manual's back picture illustration (could not find a real pic on the net). Also, a front pic and its specs included.
I didn't understand what ecc83 was speaking about damaging the PA? Can a device like H1 damage the PA?

On another note, even though I have subscribed to this thread, I am not getting any update emails when you guys post. Have to write to HomeRecording.com about this.
View attachment 97011View attachment 97010View attachment 97009
 
The PA has a line output. The manual doesn't specify whether it is a TS or TRS socket. MY guess is that it is a mono TS output.

This is the output that you would use to feed a recording input. However, I will restate the point I made in my first response: if you are trying to record a line-level signal with an input intended for mike level, you will have difficulty avoiding distortion because of too strong a signal coming in.

The Zoom H1's has a mike/line-in socket, so it can accept either mike or line level. Presumably this is controlled through the input level buttons, which may have to be set very low for line-level.
 
Super. Thanks gecko. Proceeding to order a H1. Read and saw the reviews too - seems simple enuf for a noob to operate. Thanks.
Wonderful forum.
 
2016-05-17-173405_1920x1080_scrot.webp1748_DPA-570.webp0010471_SSA-160EM_BV.webp

Reuploaded the files.
 
Aha! The line out is specified as 1V/1k and so might overload the input of the recorder. I see there is another output, "pre amp out". This is at the much more useful 200mV but I suspect is wired as an "insert" and plugging in a TRS jack will stop the feed to the PA (probably intended for use with an EQ or other feedback control system) .
The fix is easy, just link tip and ring in the jack lead but involves some soldering.

The point about amp damage ONLY applies if you are trying to tap into a speaker line, an accidental short could blow the output stage. Since the amp has line outs, not going to happen.

BTW, sorry I missed the fact that there were line outs! Put it down to age, meds, 'king eye!

Dave.
 
Not sure if rix55 has his models mixed up in the images. The specs and back view seem to be for the SSA-160EM, but the front image is a DPA-570. They do have different levels on the Line out jack and the DPA-570 does not have a Preamp Out jack.

rix55, could you clarify which PA you actually have?
 

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ecc83 said:
I see there is another output, "pre amp out". This is at the much more useful 200mV but I suspect is wired as an "insert" and plugging in a TRS jack will stop the feed to the PA (probably intended for use with an EQ or other feedback control system) .
The fix is easy, just link tip and ring in the jack lead but involves some soldering.

Dave.
Click to expand...
If the PA is indeed the SSA-160EM.........
 

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Hi Mark... you are right, the front view of the PA is not of the SSA-160M. I could not get the exact model - but took one off the net that looked the closest. But, the manuals are of SSA-160M (which we actually have). I never knew you could say a lot about a device by just its front image. Thanks for clarifying, Mark. I am going to try the Zoom H1.
 
A cable was mentioned a ways back, but I don't think detailed what you may want. The output of the PA is a mono signal (TS jack). The Mic/Line input of the Zoom H1 is stereo (TRS jack). The proper cable so you get audio recorded to both left and right in the Zoom would be ...
Hosa 3.5 mm TRS to 1/4" TS Mono Interconnect - 10' | Sweetwater.com

Amazon has it also as an "add-on" for Prime members if you might get the H1 there....
Amazon.com: Hosa CMP-110 1/4 inch TS to 3.5mm TRS Mono Interconnect Cable, 10 feet: Musical Instruments

I have an older Zoom H2 that I recorded through the Line input and it worked well. Zoom makes some decent gear for the money.
 
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