Pioneer CT-F1250 missing high frequencies

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#1
So, I've got a problem with my new-to-me Pioneer CT-F1250. I've replaced the belts and rebuilt the takeup reel motor, and so it's mechanically sound. However, it's missing a bit of high frequencies on playback. Not terrible, but obvious. In addition, when recording the EQ knob does not have enough adjustment range to ever light up both LEDs. Bias and Level adjust properly, but I turn EQ all the way to the right and it's still not enough -- tried this with several different brands of Type I and Type II tapes.

If I record a tape on my Nakamichi BX-150, it sounds identical to the CD. I can adjust the levels and then swap back and forth between CD and cassette and I hear virtually no difference (type II tape, no dolby). However, the same tape played back on the Pioneer definitely has muted highs in comparison to the CD.

I've tried adjusting the azimuth, and that has made zero difference. Heads are in really great shape, and are nice and clean. What could be causing this? I love the look and feel of using this Pioneer, and I have hundreds of tapes... I'd really like it working 100%.

Thoughts?

Charles.
 

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#2
So, I've got a problem with my new-to-me Pioneer CT-F1250. I've replaced the belts and rebuilt the takeup reel motor, and so it's mechanically sound. However, it's missing a bit of high frequencies on playback. Not terrible, but obvious. In addition, when recording the EQ knob does not have enough adjustment range to ever light up both LEDs. Bias and Level adjust properly, but I turn EQ all the way to the right and it's still not enough -- tried this with several different brands of Type I and Type II tapes.

If I record a tape on my Nakamichi BX-150, it sounds identical to the CD. I can adjust the levels and then swap back and forth between CD and cassette and I hear virtually no difference (type II tape, no dolby). However, the same tape played back on the Pioneer definitely has muted highs in comparison to the CD.

I've tried adjusting the azimuth, and that has made zero difference. Heads are in really great shape, and are nice and clean. What could be causing this? I love the look and feel of using this Pioneer, and I have hundreds of tapes... I'd really like it working 100%.

Thoughts?

Charles.
I'm no expert but I have seen the same thing and my belief was that the head alignment between the two decks is different,,how does the Pioneer play and record if it's fine then the Nak heads are aligned a little different than the Pios,,I could be wrong, I usually am
 

Northwinds

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#3
I had the same problem with a CT-F900 recently, fully serviced and it sounded like shit. It also had a minor issue with one of the tape posts not out far enough to grip the cassette gears so even though that was an easy fix, I did not want to bother with the deck because of how it sounded and got my money back
 

Gibsonian

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#4
Clean and especially demag the heads. High frequencies shall likely return, assuming your azimuth is still on target.
 
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#5
I cleaned the head already. When recording on the Pioneer, the resultant tape has less treble than the source, and the EQ calibration cannot be dialed in. It's maxed all the way to the right, and the LEDs still indicate it needs to turn further. (Doesn't matter if calibrating to Type I or Type II).

Not sure demagnetizing actually does anything, but I'll give it a shot.

Charles.
 

orange

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#6
Umm...that editing reason might be TMI.:albino:
 

laatsch55

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#7
It's also possible , and not familiar with that unit. Is there external adjustments? And is that what you are referring too?
 

Gibsonian

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#8
I cleaned the head already. When recording on the Pioneer, the resultant tape has less treble than the source, and the EQ calibration cannot be dialed in. It's maxed all the way to the right, and the LEDs still indicate it needs to turn further. (Doesn't matter if calibrating to Type I or Type II).

Not sure demagnetizing actually does anything, but I'll give it a shot.

Charles.
I have seen marked changes in high frequency response on a highly magnetized head after demag in my past. What do you have for demag?
 

orange

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#9
I have seen marked changes in high frequency response on a highly magnetized head after demag in my past. What do you have for demag?
I saved my CT-W770's recording deck with one, don't I know?
 

mr_rye89

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#10
I've got a CT-F950 with the same problem. I did all the above and even swapped the ferrite head with a sendust one and did a resistor mod on the pb circuit. Still sounds dull. I still have it, but ended up getting a BX-300.......
 

Skywavebe

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#11
I just did a CTF-1250 and I did not have any trouble with the Bias setting internally. The problem with the Pioneer manual is it makes you do all kinds of measurements and kind of makes you miss the real subject of what they are trying to get you to do. Also on mine the pots for the levels on one channel had to be changed out on one of the vertical cards. The azimuth alignment is kind of strange on how they have you set it. They have you record first and set the alignment. I got the unit to work right but I had to improvise on some of the things they wanted me to do. Way too complicated than a Tascam 122 Mk II. I guess it was designed a long time ago. This deck needs to be calibrated by a experienced Tech as some of the process makes sense as long as you have a lot of knowledge under the belt. A new guy even a Technician can get hung up on a lot of what they are telling you to do.
The calibration procedure needs to be stream lined and made less complicated.
These decks can sound good, you just need to know how to calibrate them.
The BX300 is not an easy deck to surpass and that is because Nak did such a wonderful job with those heads.
 
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My problem ended up being a bad head. Replacing it with a used ALPS head fixed the lack of any kind of hf response. Now I just need to have the deck calibrated.

Charles.
 

orange

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#14
I got mine last year and it was like new, hardly used and from a TH member I know well and trust who had it for years. I don't think that it could have been topped even if new and unboxed. Someday I'll get my 950 and have all of them I wanted to get from the seventies checked off.
 

essay

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#15
My F950 also needs new pinch rollers, the ones on there are shot.
 
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orange

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You can get them rebuilt, it's just not in my head as to where right now.

You are not going to get new ones and parts on eBay might be a crapshoot.

Terry DeWickt?

I don't even recall where the name came from, the cat fixed SOMETHING electronic.

I'm shy one 950 myself to COMPLETE my collection. I was lucky enough to get my 1250 almost like new from someone I know, and I spent the bread to do it as well. You can't cheap out on everything.
 
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orange

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Navo, where did mr_rye89 get his avatar? I need some more of that.
 

orange

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#19
That 950 has about been more elusive than a girlfriend (and that was 17 years back for the last one)...

I've been working on getting the stacks I've got interconnected and building bikes in the meantime. Might be a while still, but I have my 1250 and it still works great.
 
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Skywavebe

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#20
Nakmandan my associate in cassette repairs is able to fix these decks up but one of the problem is the heads. The head sometimes are cracked and other times can be lapped by JRF and give a better result. The other well know problem is the cracked Idler drum that there is no replacement. There is a guy who lives south of me a mile or so that has a fix with a brass ring we have used. Markthefixer is the guy from AK forum and it was funny that he ended up living in the same town as me.
 
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