Tascam 244 service manual or DBX calibration procedure?

WhinyLittleRunt

WhinyLittleRunt

Member
In the midst of working on the 38 issues I pulled out my 244 to play with, which works fine other than it say idle for a bit too long and the function belt hung up a bit, requiring me to remove it and put it back on... Otherwise it's good and works great.

The DBX does pump quite a bit, and I know by the past posts about it that there is always going to be some level of that happening, but because there are so many trimmers and pots on the encoder board itself, I can't help but assume there must be some service adjustments. Problem is, I can't find a service manual for the 244 anywhere...

Anyone have one they wouldn't mind sharing? For those who may have one, does it actually document the calibration for the DBX?
 
I think most think it is best to leave well alone with the dbx. I found that setting the bias record and playback trimmers cured my machines of pumping artifacts. Pushed to hear any at all now. I recommend you try this first!
 
Cool, I could totally do that. I think I'd need a calibration cassette though huh...

Still would like to find a manual but looks like I may just have to bite the bullet and buy one through Teac...
 
I saw a copy of the manual a while back and I'm sure it stated that no alignment of the dbx is needed unless the unit is replaced, or words to that effect and that you need some pretty fancy gear to do it properly.

I've managed to set the bias and levels on all 3 of my 244 machines pretty well without a bought calibration cassette. I know purists may wince at this but it is easier than you might think and I'm pretty happy with the sound - pretty flat response from 25 Hz to 16 kHz and no dbx pumping. I made my own calibration tape of sorts when I bought my first one (in '82!) but if you have some good recordings from early on you could maybe use these to get the playback levels more or less sorted and work from there?
 
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What procedure did you follow to set the bias? I haven't touched anything on the 244 yet as it sounds pretty good with only some of that DBX hiss/pumping artifacts but I'd like to confirm the levels and set them accordingly... I'm sure you're right I don't really need a calibration tape but I also don't have any recordings from the 244 since I just got it last year sometime...
 
I first made sure the playback levels looked good then using a freq generator app on my tablet fed a stereo signal into the aux in. I set the record level for 0dB for a 400Hz signal (the manual says -20dB but I prefer to work at 0) and recorded on channels 1 and 2 for about a minute or so. Then set the freq generator to 10 kHz and recorded for another minute. Played these back (set to remix) and looked at VU's. Most times I found 400Hz was pretty close to 0dB but 10kHz signal was down a bit so I reduced the bias until this came up to around 0 on re-recording. You have to go around several times to make sure the 400Hz signal doesn't drop too much - if it does tweek the bias up a bit. I got cocky after a while and recorded at 12.5 kHZ and even 16kHz to get good levels here - possibly at the expense of a little distortion but I like good top end. Repeated for channels 3 and 4. On one machine I had to tweek the record level trimmers near the bias trim on a couple of channels to get a sensible response. I guess I spent about an hour or so to get response within +-2 dB from 25 z to 16kHz. Used new Fuji JPII 100 cassettes which I find perfect.
 
Open up the back and there is a column of 4 cross headed bias trimmers roughly in the centre towards the front. Channel 1 is nearer the front then 2 3 and 4. These are separate from the banks of trimmers to the left and above used for record level playback level and eq. Will post a PIC next time I open up!244 trimmers.jpg

Update - just found this pic which might help a bit more!
 
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Awesome. I never knew that. I just won a 244 auction on eBay tonight and am going to fix it up. It was described as having the head stuck in the up position and a humming sound when it's turned on. It'll need a pinch roller wheel too, but I figured it was worth it for $90. This is helpful in case. The one I have never needed it but you never know
 
WhinyLittleRunt said:
I emailed him - saw that he was offering it at no cost so I'm just patiently waiting on a response.
Click to expand...

i have a copy, so if you don't hear from them after a week or two pm me and i can maybe send it through email. but, i don't know if i'd be violating any law since he did the work to scan it, etc, so that's why i say ask them first. i'd consider giving him a small donation too since he did a lot of work on it. it's a very high quality scan and imo the definitive version of this manual since the originals are mostly long gone.
 
Hi I just emailed them today. If I don't hear from the in a week could I get a copy from you as well? I'd be happy to share anything I do have - 246 service manual in pdf for example, thanks.
 
I have a 244 manual if you need. PM me so I remember. All I require of you is to go to my Soundcloud page and comment on 7 songs of yr choosing, saying things like "I have now been to the promised land," "This is beautiful," and, well, I don't want to tell you too much to write. Just pepper praise throughout. Thanks.
 
Really?

I'm not sure you can properly set up the R/P chain without a legitimate calibration cassette. The record level references off the playback level, which should be set to a know standard. Just MO & from common sense/experience. Without setting the playback as the baseline, your levels may be floating to a false set point. You may get it to work in a functional sense without a calibration cassette, but I don't think it will be properly set or truly correct.
 
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