Tape duplicator distortion

[Jccc]

Hello I know this is not Record lathe related but i was just wondering if anyone could help me out.
I have a Recordex high speed stereo tape duplicator. I forgot the model number but i can check it when im around it.

The problem is when i play back the tapes after they have been duplicated they sound really distorted and blown out sounding. Meaning the bass is really distorted and the highs are really crunchy sounding.

I have cleaned the heads with alchol and demagnitized the tape heads and capstan but am having no luck.

Also there is a vu meter on it and i make sure that the signal is not in the red.

If any one out there knows any links or know anything about these machines im open to anything.

sorry if this is not record lathe related!

[Greg Reierson]

Which model is it?

You need to make a few baseline measurements. To do that you need a known reference playback system. Any decent cassette deck you have in the studio will suffice. Since cassette test tapes are really hard to come by these days and it's too risky to put a good one in a duper anyway, you'll need to make your own:

1) Assemble a set of tones in your DAW. Generate 10 seconds of 1k at -20dBFS, then 10 seconds each of 1k, 10k and 100Hz - all at -40dBFS (multi-frequency tones are recorded 20dB below reference level to avoid tape saturation), and finally 2 minutes of 1k at -20dBFS again (that last two minutes of 1k will be to set the record level according to the VU meters on your duper when it's running at dupe speed).

2) Record this tone sequence onto a cassette tape using the reference tape deck from above. Set the record level of the deck so that the first 1k tone reads 0VU. Play the tape back to verify that the first 1k tone plays back at 0VU.

Verify the reference deck playback response:

3) Play the tape back into your DAW and note the level of each tone on the DAW meters. Set the DAW record level so that the first 1k tone is at -20dBFS and note the level of each of the other tones. Now we have a reference playback system. It may not be perfectly flat but you have written the response down for comparison in step 5 below.

Now to test the duper.

4) Put the test tape you just made into the duper and run a copy.

5) Put the copy into your reference deck and record it into your DAW like you did in step 3 above. If the 1k tone comes back too high or too low you should adjust the duper record level and run it again. When it comes back at -20dBFS on the DAW meter then you know you have the record level set correctly (you will also want to notice what the VU meters on the duper are doing. I would not assume they are properly aligned, but you never know). Finally, record the level of each of the frequencies as you did in step 3. Any differences between those readings are due to the frequency response error of the duper.

That’s a pretty quick and dirty way to get a rough idea of what the duper is doing. I skipped over all of the mechanical stuff, bias settings, EQ setting, etc. We can talk about that stuff later.

[EmAtChapterV]

These folks might be able to help you: http://www.tapeheads.net/forums.php

[Greg Reierson]

Any progress?

[Jccc]

Hello, i had to put this project to the side for a while as i had other projects i had to get finished. (Fixing the presto 6n motor, also making a cutting head mount to hold a nuemann cutting head)

I will try to run the test that you described Greg. I forgot to take a look at the model number of the Recordex. It is a really heavy duty machine tho. it can take a beating.