Tandberg 9000x Audio Quality

[NorfolkDaveUK]

My 9000x is a 2/half track .

So it sounds amazing with a pre-recorded or tape recorded on another machine , but if I record on this machine the outcome is kinda muffled.

I have adjusted the bias as per the manual (22v both side) and this has made no difference at all , the tape alignment is still factory locked , the heads are spotlessly clean and there is absolutely no wear on the heads at all . This hasnt been de-magged as I dont have one but I think the problem is more than that .

I have re-capped the machine with Panasonic`s , and that hasn`t helped either .

Any ideas anyone ? Would changing the transistors help ?

[llama]

Are you sure you are using a suitable tape? Tapes manufactured much after the machine was made will need more drive and bias than typical tapes contemporary with the machine.
Next time I'm in Norwich I could lend you a de-mag if you like.
Graham

[NorfolkDaveUK]

Thanks Graham, I`m waiting on a demag to arrive bud , thanks for the offer though . I`m using old tape , it plays ok on other machines . I think i`ll go through the service set up again and see what comes out the other end . I`m without a test tape (waiting on one of those too) so I`ll wait until l get both of those before I continue . I`ve had it on ebay for a while I was going to sell it , but its so good this one is now staying with me , Its by far the best sounding one I`ve had in a long time . Had no idea before I bought it just how good these are . I`m now looking at a 3500x 4 track to go with it . lol .

[stevehertz]

Tandberg R to R machines were always very highly rated and in Hifi Choice* tests were neck and neck with Revox.

*A5 size Hifi Choice lab test 'books' from the 70s and 80s, not the later magazine of the same name that it morphed into.

[NorfolkDaveUK]

Well, I took a chance on this one pretty much blind about 4 months ago . I paid £100 for it , and it had logic issues . I replaced all of the logic chips after a ton of agro getting them from Russia (the wait was agonising) and that didnt fix it . So I was pretty gutted . Then all of a sudden a logic board turned up on ebay in the states (£45 shipped) so I just had to jump on it . Put that in and it just worked . Sounded amazing so I immediately re-capped it , did and initial service on it , the bias was well out , putting that in transformed it into and astounding sounding machine . So i can see why it would be on par with revox it sounds way better than my 4 track A77 for sure .

[ricard]

Interesting thread. I've got the successor model, the 9100X (actually two, one as a backup), and I remember testing it against a friend's A77 many many years ago and thinking the Tandberg sounded better. Over the years I've been wondering if my judgement was clouded at the time, but after reading this thread, perhaps not.

As for the sound, I was told by a Tandberg service representative at the time that Maxell UD was the tape for which the machine was designed, indeed, I subsequently used only Maxell UD (and also the back coated XL1) and was always pleased with the result. After setting bias for UD tape, I've noted that BASF LP35 was overbiased with a consequent lack of treble. When I bought the machine, second hand, there was some high bias Agfa tape on it, and the store had set the bias accordingly, and while it sounded ok, either the high bias caused there to be less power for erase, or the erase head was struggling with the high coercivity tape; either way, it couldn't erase the tape properly. But with UD all was fine.

When setting up the bias, I have frequently used the echo (S ON S to the same channel as being recorded) function: I record a short blast of white noise, and over successive echoes the sound will either get thinner or more bassy. In the former case, increase the bias, for the latter, decrease it.

Can't offer much of an idea for the muffled sound though, unless the tape in question is severely overbiased.

[NorfolkDaveUK]

Thanks Ricard I really appreciate your input. I just bought a 3500x than needs belts (you`ve prob seen it on ebay with the front off ) . I gave £80 for it . I think its worth that will be interesting to see the difference between the quarter and half track versions of the heads .

Thanks for the advice on the bias setting . I didn`t really know how to go about it on this machine . I kinda use to the "revox method" of setting it with a scope . I will have a play with it and see what I can do . From what you are saying it sounds like it is probably a bias issue . It sounds "ok" its just lacking top end . Its not completely muffled or anything . Sorry I probably over stated the problem .

[NorfolkDaveUK]

nevermind....

[TIMTAPE]

Assuming everything else is correct... bias is to do with the tape, not the machine. When you reduce bias below 22v, even well below 22v, what happens?

[Ted Kendall]

If all else fails, fall back on the way the pros have always done it.

Put a meter on the output of the machine. Feed in 10kHz at a moderate level, say -15 on the meter. Reduce the bias as far as it will go. Now record said tone and monitor the output whilst increasing the bias. The output will rise to a peak and then fall away. Your optimum bias point is probably about 3dB over the hump. Repeat for the other channel.

Now, there are two things you need to check. One is that the output level at 10k is the same as at 1k - on some domestic machines, the fine bias setting is used to trim the frequency response. The other is that the two channels are in step. Increasing the bias level causes the effective position of the trailing edge of the record head gap to move, thus causing a phase shift between channels. Easiest way to see this is using a dual-beam scope or a Lissajous (X-Y) display.

[NorfolkDaveUK]

This is the way I`m used to doing it.

[Ted Kendall]

Fair enough - what happens if you do it like that?

[NorfolkDaveUK]

I haven`t yet . lol . I just went by the book . I will give it a go later this afternoon and let you know I`m knee deep in them at the min so trying to juggle the ones I`m selling against the ones I`m keeping haha I`m sure you know how that goes .

[Ted Kendall]

Tell me about it...

[NorfolkDaveUK]

So i just put a reel of Agfa tape on her and she sounds incredible , so it is indeed a tape/machine issue . I know what to use now . This agfa tape is the really dark stuff , (not the cheaper brown stuff) and it really has brought the machine to life . I just need to get my hands on a lot more of it now . I`ve got probably 10 reels of it so I`m ok for now . I just recorded Rumours (mac) onto it and wow. Amazing . I`m using a 1970`s amp too (sony str) with my mission speaker its just amazing quality .

[barrymagrec]

I`m sure you are too experienced for this but my former boss once installed four tape machines in Canada and then went on to Australia to do the same thing, while there the Canadians said all their machines would now only record muffled and low level and the local Ampex guy had no clue what the problem could be.

He flew back to Canada and discovered that they had reversed the Zonal matt backed tape and were trying to record on the backing.........

[NorfolkDaveUK]

I dont know about too experienced , but i didnt do that. lol.

[TIMTAPE]

Originally Posted by NorfolkDaveUK

So i just put a reel of Agfa tape on her and she sounds incredible , so it is indeed a tape/machine issue ...

Yes, probably the current record bias level just happens to match that Agfa tape you put on. You could optimise the machine's bias level to other tapes too.