I'm trying to transfer over a pile of cassettes to CD using my Tascam 122 MkIII deck. Even though I do follow the advice of the tapes and switch the Dolby B 'on' when playing the tapes to the computer for processing and burning, I find the sound somewhat muddied. Turning it off certainly gives the sound a good deal more brightness.
Is it just my ears, or should I switch the Dolby off on playback? It's always been my understanding that as far as Dolby was concerned what got used going in had to be matched at output for faithful reproduction, right? I'm just not hearing it that way.
Thanks.......Tim
As a still active tape guy, I see you are finding the problem with tapes.
There are a number of reasons for your problem.
First clean the tape heads with pure isopropyl alcohol on Q-tips. Clean all the heads, guides, capstan and roller.
Next demagnetize the heads with a head demagnitizer. With the device on move it carefully to each of the parts of the tape path, especially the heads. Move it away from each part slowly, with it on. Do not switch it off close to any part, especially the heads, or you will magnetize them. When you do the demagnetization, make sure the deck is OFF, otherwise you may overload the playback amp and blow it.
The above measures usually help a lot.
However it is very likely you have an azimuth problem.
Tape head gaps must be aligned carefully. They have to be in perfect zenith and above all azimuth alignment. This means the gap must be perfectly vertical to the tape, in its path. If it is not there is highly significant HF loss even with VERY small fractional degrees of misalignment.
The play back head is aligned using a laboratory alignment tape. The azimuth band is a high frequency tone 10 Khz for cassette and 15 KHz for reel to reel.. They cost a fortune and I have one for just about every type of two and four track machine both reel to reel and cassette.
You adjust the head with the alignment single phase method first, to get the greatest output watching it on a very accurate amplified meter. You do this to make sure you are not on a secondary or tertiary peak. When you have found the high peak, you then do a careful alignment using the dual phase method.
The alignment is so critical that this procedure needs repeating on a fairly frequent basis.
Now here is the thing you need to understand. All but the highest of the highest end cassette machines were two head. That is to say there was an erase head and a single record playback head. A few were three head, with seperate heads for record and playback. Almost all the decent reel to reel machines were three head.
The point is that if the record and playback heads are the same, there will be no azimuth error when playing back a tape on the machine it was recorded on soon after the tape was made. However if you take that tape and play it on a different machine, the chance for azimuth error is high, unless both machines have been obsessionally maintained.
Obviously if it is a three head machine, the record and playback heads have to be kept in perfect alignment, otherwise you have huge losses. In three head cassette decks, the record and playback heads were physically in the same case as a rule, so that the record and playback heads stayed in the same azimuth alignment, even if they were both wrong.
It is now a long time since tape machines were produced, for home use at least, and tape head alignment was beyond the competence of all but a few owners, so you can pretty much take it as a given that all machines are by now out of azimuth alignment with one another. So severe high frequency loss is going to be the rule rather than the exception. The problem is compounded by Dolby codes, as those codes compound and increase the frequency response errors from azimuth misalignment.
Aligning tape machines, which include not only head alignment, but setting equalization and bias, is rapidly becoming a lost art, and art it is. I'm becoming one of an ever decreasing cadre. ATR services are doing their best to try and reverse the trend by holding frequent seminars to teach what is becoming an extinct art. They hold them at various locations around the country. Registration fee is about $2000 though.
If you click on the link in my signature, you will see some of my tape machines and turntables.