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Author Topic: Level problems with pre-records??  (Read 7062 times)

Offline heideana

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Level problems with pre-records??
« on: February 21, 2007, 04:41:10 AM »
Is it my imagination or do some pre-records have mismatiched channel levels?  I'm not sure if its' just the way vu meters respond to various frequencies or really mismatched signal levels in the right and left channels on some of my pre-records...
Studer A810 and Otari MTR-15...Klipsch CWIII's, KG2's & RF7's

Truth is a kind of error, so vaporize it to find your way to heaven, or at least to a smile...

Offline docb

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Re: Level problems with pre-records??
« Reply #1 on: February 21, 2007, 12:32:16 PM »
That's a really tough one to make a generalization about. If it's a consistent problem with most tapes it points to a need for realigning your playback head. If it's just here and there it could be that you need to adjust the head alignment a bit for a given tape. At least that has been my experience with prerecorded quarter tracks on occasion. It could also be that the offending recording wasn't balanced L to R in the first place.
Dan "Doc B." Schmalle
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Offline heideana

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Re: Level problems with pre-records??
« Reply #2 on: February 21, 2007, 03:25:12 PM »
Thanks Doc!  Its' not a consistent problem and usually when I think there's a mis-match it turms out to be "dynamic range".  however, a few aren't dynamic range, which makes me wonder about the possibility of mismatched recording levels...my hunch is that not all mastering is sterling and mistakes happen????
Studer A810 and Otari MTR-15...Klipsch CWIII's, KG2's & RF7's

Truth is a kind of error, so vaporize it to find your way to heaven, or at least to a smile...

Offline docb

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Re: Level problems with pre-records??
« Reply #3 on: February 21, 2007, 05:25:00 PM »
I would be hesitant to assume it's the mastering engineer's fault. If it happened in the production chain the mixing engineer, if there was one, would probably be ahead of him in line if there was a mixdown.  If it wasn't multitracked, then maybe the recording engineer is to "blame" (or maybe he wanted it that way?). And any of those guys might just blame the producer! But - it could also have been that the duping master machine or duping slave was out of alignment. You might need to compare several copies of a given album to start to get a handle on what is going on.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline ironbut

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Re: Level problems with pre-records??
« Reply #4 on: February 21, 2007, 07:15:09 PM »
I listen to a lot of prerecorded tapes. I was buying them hand over fist for a while and only had time to listen to each one once to check them and see how much I enjoyed the performance. I noticed one day the left channel was consistently lower in level. I went back to some of the the tapes that I didn't notice this problem on but it was there also. It turned out that, although I'd been cleaning the heads about every 6-7 tapes, I hadn't been careful to clean the entire head. The RS1500 has head shields and the angle that you have to use to get at the heads lends itself to not getting to the edges of the head. It wasn't like there was a huge amount of build up there but enough to reduce the level on that one channel. The difference was instantly noticeable.
steve koto
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Offline xcortes

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Re: Level problems with pre-records??
« Reply #5 on: February 27, 2007, 09:12:50 AM »
I'm having the same imbalance problem on my RS1500. It happens on the 4 track head and apparently not on the 2 track head although I have to do more extensive testing. Imbalance can be as much as 3dB based on the meter readings. I cleaned the heads but the problem is still there. The tech who sold me the deck assures he checked for alignment and that it must be a head cleaning issue. He has been very helpful and offered that if I can't correct the problem I can send him the headblock for him to align it.

If I take the headblock off, however, I might as well send it to JRF magnetics for a full service. What do you think?

The deck is in very good condition mechanically from what I can tell. Runs very smoothly and silently and most of all, aside from the balance issue it sounds very, very, good. However if the balance issue arises from a misalignment head, well, it can only sound better right?

Xavier Cortes
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Offline docb

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Re: Level problems with pre-records??
« Reply #6 on: February 27, 2007, 09:49:23 AM »
Alignment relies upon a system of components, not just the positioning of a single part with respect to one other part. All a tech can assure is that he aligned your machine to work with his alignment tape. If we presume the guy really did align the 1/4 track head and that the tone tape was in good condition and the tracks are mostly where they are supposed to be on the tape -

Possibly something moved during the transport or shipping of the machine.

Possibly your tapes are a bit edge damaged or otherwise deteriorated. Are they all from the same source? Another machine might have munched them up on one edge.

Possibly one of the screws that mounts the spring adjustable guides got bent. I found this on one of my 1500s the other day. Possibly one of the tension arms got bent. I found a 1mm difference between arm-to-faceplate distance of the supply side and takeup side tension arm rollers on the same machine, which required the addition of a shim to bring the "low" one back to the proper height. I should note that after I made that correction and some mods (which I'm not quite ready to discuss) the machine packs tape in play so well it looks like a brand new reel.

The obvious place to start is to get the 1/4 track head alignment checked and adjusted if necessary. Because of the number of tape path adjustments on a tape deck like the RS1500 a tech can't possibly align your headblock as accurately as possible without it being attached to your machine. At best he would put your headblock on a different machine that might have the spring mounted guides set at slightly different heights than the ones on your machine, and that can throw everything off. At worst he would just do a visual alignment, which is only a rough estimate and might make things worse.

Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline ironbut

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Re: Level problems with pre-records??
« Reply #7 on: February 27, 2007, 07:05:48 PM »
Just to let  you know, it took more than one cleaning to clear up the problem with my deck. I was using Q-tips. I think it was partially because of the curve of the tip that I wasn't getting to the outer edge. I have some old Revox head cleaning pads that are square and they clean the edges as well as the center of the heads. You almost have to jam the Q-tip into the head shield to really get at the edges as well ( I said ALMOST). Now that the whole head gets cleaned each time, it isn't that hard ( there's no old build-up which seem twice as hard to get off ). I'd say, before you send you deck or headblock off, clean the heads with the headblock off so you can really get a good look at them with a loop.
BTW the headblock is super easy to remove (4 screws).
good luck shipmate
steve koto
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Offline docb

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Re: Level problems with pre-records??
« Reply #8 on: February 27, 2007, 07:38:36 PM »
The isopropyl alcoholics here may get their panties in a bunch over this, but I have found that V&M naptha or lighter fluid (same thing) works wonders on gunked up RS1500 heads, fixed guides, the capstan and the reversing idler. I wouldn't use it on the tension rollers because it could strip the lube out of the bearings and DON'T GET IT ON THE PINCH ROLLERS! Naptha is also called rubber solvent, for a good reason. Alcohol isn't the best thing for rubber either. For cleaning the pinch rollers try 409.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline xcortes

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Re: Level problems with pre-records??
« Reply #9 on: February 28, 2007, 09:15:50 AM »
Very late night yesterday I read Steve's post and I got off the bed to clean the the head with strong emphasis on the edges. Wow, immediate results. Both channels pretty much in balance now. I didn't have a chance to do an extensive testing but I can assure you that things really improved.

There's still some less output from the left channel but you have to make an effort to detect it. I may need to do some more cleaning and try cleaning taking the headblock off for better access to the edges. Maybe I'll even try some naphta (would zippo lighter fluid work?). Anyway I seem to be in the right track.

Hey Steve: You'da man!
Xavier Cortes

Offline ironbut

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Re: Level problems with pre-records??
« Reply #10 on: February 28, 2007, 08:07:31 PM »
Happy to help. I went around and around with mine but I knew that it was working OK at one time. Once you get it really clean, it's a whole lot easier to keep it clean. Those head shields are a bitch to work around!
steve koto
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Offline heideana

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Re: Level problems with pre-records??
« Reply #11 on: March 07, 2007, 03:26:01 PM »
I decided to play the few tapes I was having level problems on another machine to see if it was an alignment problem with a particular machine and was able to duplicate the level problem on my other two Technics, which leads me to suspect that some tapes do have some "duplication issues".  I also noticed that the level imbalance between channels is usually only one side of the few questionable tapes....

For what its' worth, I'm primarily recording/dubbing to my PR99's and have found that using a mixer to set levels has made my life much easier...

Thanks all for sharing your experiences!!!
Studer A810 and Otari MTR-15...Klipsch CWIII's, KG2's & RF7's

Truth is a kind of error, so vaporize it to find your way to heaven, or at least to a smile...

Offline scully280

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Re: Level problems with pre-records??
« Reply #12 on: March 08, 2007, 10:16:59 PM »
For Stereotape and Barcaly-Crocker tapes there were always Dolby Tones with B-C giving us the luxury of tones on both sides.  This allowed the fussy user to match the level on the tape to the Dolby calibrated play level on the Dolby decoder.  My experience with bunches of these tapes is that the the Dolby levels seldom match from side to side and tape to tape and sometimes are off by a lot at least from side to side.  Not surprising that the levels vary from tape to tape as different batches of tape will have different repsones, but the channel to channel balance problems are annoying and harder to attribute; perhaps just the vagaries of high speed dubbing.  Makes me hope that the Tape Project tapes are subject to the same type of quality control for 1:1 dubs that the site in Ironbutt's post "Some R2R resources for first time owners" talks about for 70's broadcast automation dubs. 
Richard Lane
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Offline EMB

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Re: Level problems with pre-records??
« Reply #13 on: July 16, 2009, 09:58:02 PM »
Are you playing a quarter track tape on a half track head?