Hello everybody,

this will probably sound like a dumb question to most of you, but I would really like an advice from some of you reel to reel guy.

I just bought an Akai GX-636 and am trying to understand whether the quality of sound I am getting from the deck is what I should expect or it rather needs a tune up in the head section.

I know the heads of this deck are made to last forever, and a visual ispection show no visible wear anyway.
I cleaned the heads, pinch roller and company with alcohol (no, not the rubber parts).

Now, the test I am doing is not probably the best. I am using an used tape that came with the machine, of which I don't know anything, so I am keeping setting on low noise position (does not seem to make a difference, though).
Using a CD player as a source, I am recording some jazz music and by switching between source and tape, I am comparing the sound quality of the recording with the original source. At 3"and 3/4 I am loosing a large part of the high frequencies, it sounds rather dull. This happens in both directions (this is an autoreverse deck).
If I try the 7"1/2 speed things get really a lot better, but still if I switch between source and tape I can hear the recording is still missing some quality in the treble.

The dumb question is: should I expect such a major loss of quality recording at 3"3/4 speed on this deck, or could it be that a demag and/or alignment is needed?

I read the manual says response should be 30-20000 Hz at the lower speed, but maybe this does not refer to the actual quality I can get from the tape.
Also, tape is probably old, but I don't think that should make such a big difference, should it?

Well... I would really like to hear from you, so I know if there's something bad about the deck or not. My intention was to use it at 3"3/4 to get 3+3 hours of music, but in the present situation the quality is really not good enough.

Thanks in advance for your patience!

Rick

Depends on what tape you are using. Do you know what kind of tape it is?

The tape used can make a big difference here, and not knowing what you are using make it hard to answer your question. But at the moment, if I had to guess, I would say that is sounds like your bias may be a little high, and/or you my be recording a little too hot.

Most good reel to reels can usually go up to about 17kHz @-20dB @3.75 ips before starting to roll-off. If you can still hear 20kHz, then you may well notice a dulling of the extreme top-end on some material. At 7.5 ips there should be no audible dulling for a properly biased tape.

However, what you really loose with the slower speeds is HF headroom. At 3.75 ips at higher record levels, it won't be able to high-amplitude- HF info without it saturating the tape, which can result in subtantila dulling of high-ampliture highs over 10kHz.

But if I am right, and your bias is a set too high for the tape that you are using, then this would cause very subtantial dulling of the highs, and loweing the bias, or getting a slighlty higher biased tape is likely to fix your problem.

Another possibility is that you actually do have head-wear (Akai heads, while relatively long lasting, don't last forever) and that you simply don't know what to look for. On the glass akai heads, this is seen as a dulling of the apex of the heads.

The tape used can make a big difference here, and not knowing what you are using make it hard to answer your question. But at the moment, if I had to guess, I would say that is sounds like your bias may be a little high, and/or you my be recording a little too hot.

Most good reel to reels can usually go up to about 17kHz @-20dB @3.75 ips before starting to roll-off. If you can still hear 20kHz, then you may well notice a dulling of the extreme top-end on some material. At 7.5 ips there should be no audible dulling for a properly biased tape.

However, what you really loose with the slower speeds is HF headroom. At 3.75 ips at higher record levels, it won't be able to high-amplitude- HF info without it saturating the tape, which can result in subtantila dulling of high-ampliture highs over 10kHz.

But if I am right, and your bias is a set too high for the tape that you are using, then this would cause very subtantial dulling of the highs, and loweing the bias, or getting a slighlty higher biased tape is likely to fix your problem.



Thank you for your advice,
As I mentioned in my original post, I have no clue about what tape it is. It comes in a no-brand reel, has some classical on it, and it is rather darkish in color (if that means something to you).
I don't think I have saturated the tape headroom, as I recorded some jazz with VU never going over 0db ... OK, I am not sure the VU are correct, since this deck is preowned, but what I mean is, the record level was not set very high.

No way I can hear up tp 20 KHz! I believe (but this is just a guess) that
the cutoff from the deck is around 14 or 15 KHz - anything over this is gone.

You talk about the bias. This deck only has two positions for bias, Low Noise and Wide Range. Manual says reference is Scotch 176 for the former and Maxell UD for the latter. I tried with both BIAS positions and it does not seem to make any diffence...

Just curious, what would happen if the tape was actually an EE tape, which of course cannot be used on this deck? Would I get a dulling of high frequencies?

I have ordered some RMGI new tape that should be equivalent to the BASF LPR35, any idea what the setting for this one should be?

Thanks again,
Rick

Thank you for your advice,
As I mentioned in my original post, I have no clue about what tape it is. It comes in a no-brand reel, has some classical on it, and it is rather darkish in color (if that means something to you).
I don't think I have saturated the tape headroom, as I recorded some jazz with VU never going over 0db ... OK, I am not sure the VU are correct, since this deck is preowned, but what I mean is, the record level was not set very high.

No way I can hear up tp 20 KHz! I believe (but this is just a guess) that
the cutoff from the deck is around 14 or 15 KHz - anything over this is gone.

You talk about the bias. This deck only has two positions for bias, Low Noise and Wide Range. Manual says reference is Scotch 176 for the former and Maxell UD for the latter. I tried with both BIAS positions and it does not seem to make any diffence...

Just curious, what would happen if the tape was actually an EE tape, which of course cannot be used on this deck? Would I get a dulling of high frequencies?

I have ordered some RMGI new tape that should be equivalent to the BASF LPR35, any idea what the setting for this one should be?

Thanks again,
Rick
The RMGI LPR-35 should bias very closely to Ampex/Quantegy 456/457. I would expect that this is reasonably close to Maxell UD, although not exactly a perfect match.

EE tape would be underbiased on your machine and would sound extremly thin, and bright, and would have rather high distortion.

Yeah, as reading from the tape occurs after it has been recorded, It would make sense that the tape is not properly biased, or just bad tape. If the tape is pretty old, most likely there will be loss, especially in the high frequencies. I would try some other tape just to see if you noticed a difference in the sound.