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Old 25th February 2012, 10:37 PM   #1
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Default Do I need a pre amp?

Hi, I'm trying to reformat a bunch of old cassette tapes, some of which are somewhat worse for age. What I'm trying to do is connect a Samson e30 graphic equalizer downstream from an old Sharp analog tape deck. the equalizer is then plugged into my computer via an RCA to usb interface.
The problem is that when the equalizer is off I get music from my speakers, but when it's on, I do not. Do I need to install a pre amp between the equalizer output and the RCA/USB interface?
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Old 25th February 2012, 10:56 PM   #2
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Hi walkinman, I've moved your post to analogue source as I think that is the better match.

It is very odd that it works when the EQ is switched off, but not when it is switched on. I'm assuming that the EQ has a relay bypass that loops input to output when the unit is physically switched off. There may be a fault with the EQ. When you turn it on the bypass is deactivated, but the output does not work. Can you verify if the EQ works with other equipment?

Tony.
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Old 26th February 2012, 12:16 AM   #3
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Check your connections. Input/output swap may work bypass, not when the gizmo is engaged. If there's more than four jacks on the EQ, it has a tape-loop; don't use that.
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Old 26th February 2012, 12:43 AM   #4
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Thanks for the interest and help. The equalizer has one 1/4" jack for input and the same for output.when the unit is turned off, or set to "bypass" I get audio output from my computer speakers. When the unit is powered on and bypass not energized, (off), I get some audio, put it is barely, and I do mean barely, audible.
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Old 26th February 2012, 01:07 PM   #5
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Default equalizer outout

Last evening, I disconnected the samson from the tape deck and interface leading into the computer. I then verified all my connections; Ie: tape output to equalizer input, equalizer output to interface and USB input on the computer.
I put a tape into the deck, opened Audacity, (the program I'm using to reformat and copy the tape media to WAV files), turned on the equalizer and hit "bypass". The audio was fine. Then I turned the bypass off. The volumn dropped dramatically; it became somewhat hard to hear. I increased the gain on the equalizer all the way, and moved the sliders all the way up. The volumn became better, but obviously, (after moving the sliders), the fidelity left much to be desired.
I'm certainly not any kind of audio expert, not by anyone's standards, but it seems to me as though I'm just not getting enough of a line signal downstream of the equalizer for the computer's sound card to amplify enough.
What confuses me is the fact that when the equalizer is switched off or switched to bypass, everything is copacetic.
I really do appreciate any and all help that you, Tony, and anyone else can give me. Thanks, John
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Old 26th February 2012, 07:33 PM   #6
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Bad equalizer.

Bad cables. Yes, it works in bypass; but the E30 has balanced in/out. These usually work with your unbalanced tape and USB RCA out/in, but there are some cables which do not connect 1/4" TRS to RCA correctly.

> equalizer has one 1/4" jack for input

Should be two, Left and Right.

Whatever.... you do not need a "preamp". The flat-EQ setting should give the *same* audio level as the bypass, no extra boost should be needed.
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Old 26th February 2012, 07:52 PM   #7
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Thanks PRR. Should I maybe try using the XLR connections on the equalizer? It would necissitate finding some sort of conversion cable to go from male TRS to male XLR. If it's made, I think I can probably find it. Would a better option be to use a better quality set of RCA cables? By the way, the only way I could find to use the RCA cables I'm currently using, was to buy an RCA to TRS adaptor, (stereo) from ,(please don't laugh), Radio Shack. The connections on the back of the tape deck are RCA, while on the back of the equalizer are either TRS or XLR, (one of each for both input and output. Again, many thanks. The opportunity to ask someone who, unlike me, knows what he's doing is invaluable.
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Old 26th February 2012, 08:04 PM   #8
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Hi walinman, do you need to use the equalizer at all? EQ'ing the tapes will result in something different to the original (that may be your intent). It sounds like the equalizer is faulty, if you get an ok signal to record when it is off or in bypass then you can still do your recording. Fixing the equalizer then becomes a secondary consideration

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Old 26th February 2012, 11:59 PM   #9
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Great point by Wintermute. I'd at least make the initial copy with no EQ, so you have at least one unadulterated copy of the original tape material. After it's digitized, there are many options.
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Old 27th February 2012, 03:23 AM   #10
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> RCA to TRS adaptor

No.

You want two Mono (Left and Right). Actually four (L-in R-in L-out R-out).

These:

6-Ft. Shielded Cable, 1/4" Plug to Right-Angle Phono Plug Catalog #: 42-2440 $5.99

6-Ft. Shielded Cable, 1/4" Plug to RCA Plug Catalog #: 42-2373 $5.79

Yowsa, 24 bucks is a lot to pay for four 2-buck cords.

It is possible your Stereo adaptors will work if you only use the Left RCA on each one.

> make the initial copy with no EQ

That's my normal policy when making dubs to a "perfect" recorder. Take it verbatim, *then* fiddle for best sound.

In this case, I'm silent. walkinman probably knows his tapes and their flaws. Doing some EQ real-time is quicker than doing EQ later. Depending on the CPU and the apps available, post-processing could add 10% or 500% to the total time to process the pile of tapes. (Batch-processing on a fast CPU is fast; I started with slower CPUs and without a batch-EQ app and my butt got sore mousing files around.)

Also the app matters. Audacity is great for the price and the process the developers intended, but I've never been fond of it for straight stereo sweetening. Apparently many of its awkwardnesses can be covered with 3rd-party plug-ins, but some are beta-quality or under-documented. I much prefer CoolEdit 2000 but of course that's long-gone if you didn't get the unlocker before Adobe ate it.
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