Beocord 9000 - recent aquisition

ChristianThomas — Wed, 01 Jun 2011 16:34:39 GMT

Hi Guys

***This was originally posted on the Nakamichi forum, and it was suggested I reposted it here***

** Later it was suggested I post this effectively technical enquiry in the Workbench forum **

(I might point out that for all this advice, I have yet to have had any help :-) )

The Beocord 9000 is now turning and it works. Praise the Lord. I can hear
some great things, but only in parts. Otherwise it’s a pretty mixed bag,
and on some material I have felt my system really struggling to make sense
of things coming from it. In some ways it has taken me back to places I had
forgotten about, being truly awful on bad tapes. Not having Dolby A doesn’t
help – it has everything else up to HX-Pro (though where that is I can’t
immediately see) so a large number of recordings are going to be out of
bounds – and an FeCr setting doesn’t quite make it right.

Believe me, I am trying to like this deck, and I do hear some great things.
It is more detailed than the Bx-300, but I don’t have the feeling on speed
stability or sense of power of that machine. I’m not sure if the flat belt
I bought was new and if MikeM is reading this, perhaps he can tell me. I am
getting all sorts of modulation from time to time, and it’s really
intolerant of stretched or misused tapes. I’m building up my cassette
collection from charity shops so one can rarely tell their condition, but
these are the same tapes played on the BX-300.

It doesn’t sound to me as though it’s shagged out. In fact my suspicion is
that it has been underused. There isn’t that soggy, soft sound that I know
from amplifiers where the supply capacitors have really had their day. Nor
do I have the sense of a general roll off from the heads being worn. As I
say, while not really where I expect things to be nowadays – where we take
the top end for granted – it really seems pretty good up there given the
medium. In fact, if I could get the rest of it right I’m sure it wouldn’t
notice for a moment.

I wasted £3.99 on eBay for a service manual which I could barely read, only
to find they can be had for free at beoworld.com. From looking at the
innards, not the manual, it seems the head amplifier centres around a very
old TLO72 which would explain (to me at least) quite a bit of the sound. I’m
fond of this as an op amp because it’s sharp and lively and has plenty of
get up and go, but it’s not the finest thing around. It will sound cleaner
than many of the contemporary op amps and seems to be nicely balanced out
here. But it might also explain why I don’t feel the power and smoothness
in orchestral build-ups – and there really does seem to be a lack of bass in
this respect – though what is there is really quite good. But there are
polystyrene capacitors abounding in the signal path and this too (though I
have never tried them alongside a TLO72) would also give wonderful results
in all detailed ways.

It’s the modulation problems – and these can be right up into the lower
midband – the speed stability and the sheer crappiness on less than perfect
tapes (and I also get a feeling that this is not just the physically
imperfect but also less than ideal quality seems to be penalised more than
on the Nak) that really need sorting out. I don’t really know where to go
on this so would like to hand it over to the experts. I don’t believe the
machine is as bad as I’m hearing. I may not think it is yet a Nak beater
but I would like to give it a chance.

But nor do I think it is entirely the transport mechanism that is at fault.
I suspect that there are things going on – beyond it just needing a damned
good service – that only those in the know will know. I can get a new belt
for the flywheel, and the pinch roller rubber is slightly perished, but
instinctively I feel the problems run deeper.

I have some good kit here with which to test it, including an Audio
Precision analyser but really need some guidance as to what to do next, not
least knowing whether I can do it stand-alone or need some independent test
tapes. (The AP can make test tones that it can recognise -certainly on a
CD, so presumably on tape too, though I don’t have a lead to try it - and
then tell you the distortion as it picks up the fundamentals.) I suppose I
ought to be able to work out a mechanism by which one can tell the alignment
from this, or it must be in a paper somewhere, but guidance is always
welcome from those with experience. I am only too happy to share any and
all of my findings with the group as a whole – and tapes if it comes to
that. Incidentally, this is my attitude in all things, certainly to the
bounds of what is fair, though I won’t be making tapes all day.

Thanks for all your help so far. I know this is not a Nakamichi deck, but
it probably deserves a place in the Pantheon of good decks, even if not on
present showing.

Best wishes to you all

Christian Thomas

PS BTW, I am in the UK, unlike the majority here who seem to be in the US.
It means I have to miss out on an awful lot of good decks going free, but in
this instance it may have also a bearing on what you can ask me do on this
topic.

Filed under: Beocenter 9000, BeoCenter 8500, beocord, BeoCord 9000 operating problems, 8000, 9000, 8400 [Edit Tags]

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Beocord 9000 - recent aquisition