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Beo Master 7000
62 replies
wrote
BM5500 and BM6500/7000 have different software levels.
A BM5500 has up to 60 volume steps, but the BM7000 has 78.
60=78, it's just a software question... the real hardware chip for volume is identical and has 255 steps.
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Both my 5500 and 7000 vol go from
00-78. If you could tell me what chip it is
would it be possible to copy the software from my 5500
on to a blank chip to replace in my 7000 as I have the programmers to reprogram chips.
It's just a thought! because this vol issue is driving me mad. The sound is audiable but it is
really low until it gets to 18
Thankyou Henry
Can someone please post a link to Die_Bogener's write-up on upgrading the BM5500, 6500, and 7000 preamp?
Thanks much,
Aaron
Hi Aron
If you try Die-Bogener's mod
could you let me know how it goes.
Thankyou Henry
I asked the tech guys at B&O, this is their response:
"En af vore teknikere, har nu set på din e-mail.
Vi kan sige, at de nævnte kondensatorer ikke har nogen indflydelse
på lydkvaliteten. De er indført som en slags sikkerhed, hvis volumen bliver
så højt at lyden "klipper", dvs. når der sker en forvrængning. Men de har
ingen indflydelse på lydkvaliteten ved almindelig afspilning.
Med venlig hilsen
Bang & Olufsen a/s
Helle Pramanik
BeoCare"
- which translates into this in english:
- "One from our technical staff has seen your mail.
We can say, that the capacitors in question have no influence on sound quality.
They have been introduced as a safety precaution if the volume gets turned up
enough to cause clipping, in other words when it starts to distort. But they
have no influence on sound quality under normal playback circumstances."
So my guess at soft-clipping was not too far out and I can see from the schematics that
the anti- self-oscillation functionality lies in there as well.
I've seen a case where mains fuses were bypassed to "minimize
mains resistance" which should also improve performance - 'nuff said.
I've stated my opinion and advice regarding these caps (which also goes
for any other safety precaution introduced, especially during production) in this
thread already.
Which advice owners choose to follow and which modifications to introduce in their own machines is up to them.
Eventual consequences likewise.
I will not comment further on this matter other than ask people to inform future owners of any
safety mods made in an eventual selling of the item.
Martin
Well I done it and it the improvement of sound is without
a shadow of a doubt better.
My amp is still playing and there is no distortion what so ever.
Like I said before I haven't ask anyone to do it.
I only put this post up to say thankyou
not for any other reason.
Certainly not to get into a dispute about it.
I looked at Die-Bogener post that you directed me to
and it seems to me more risky what he's done he ripped
half the pre amp to shreads.
It's seems like you have developed a grudge . I spoke with a B&O engineer 30yrs of experiance
and he told me it was ok to do.
6th January 2009
If you have owned a lot of B&O equipment then you will have probably noticed that thesse models give a slightly disappointing sound when used with passive loudspeakers when compared to some of the earlier designs. This is surprising as the power amplifier circuit is very similar to that of the Beomaster 2200, Beomaster 5000 and the Beocenter 7700 (amongst many others), all of which give very satisfactory performance.
The Beomaster 5500, 6500 and 7000 have a rather basic pre-amplifier circuit compared to that used in the original 5000 model but this is not the cause of the problems, the same arrangement is used in the Beocenter 9000 where it seems to work reasonably well. Therefore the power amplifier circuit was investigated to see what could be causing the trouble.
The only substantial difference between the Beomaster 5000 circuit and that used in the later models is the addition of four 220nF capacitors C215, C216, C415 and C416. They are not shown on all the Beomaster 5500 circuit diagrams but many sets have them. As these do not appear in any other versions of the circuit it seemed safe to remove them and see if the performance improved. With the capacitors in circuit the sound from one Beomaster 5500 was lifeless, bland and uninteresting, without them it was more similar to a 5000, engaging and lively with a full, rich tone.
It is not clear what the purpose of these capacitors is but performance definitely improves if they are disconnected. Before doing this make sure that the muting relay 3RL1 is in good condition (contact resistance less than 0.5R at rest) and that the output bias current for each channel is correctly set. [Beomaster 5500, Beomaster 6500, Beomaster 7000]
THROW ME OFF THIS FORUM AS I PERSONALLY THINK YOUR A .
I am happy with what I done
the sound has improved ten fold.
I spoke with a B&O engineer of 30yrs experience and showed
him the mod I found on beo centrle and he said go for it and I did.
First you tell me it'll go up in smoke then you say it'll distort the sound
It hasn't done either.
"First you tell me it'll go up in smoke then you say it'll distort the sound"...
I did neither.
Martin
Martin
you wrote
Won't you face a serious risk of self-oscillation in the amplifier if you remove the feedback caps ?
It's quite common to see unstable DC-coupled amplifiers like this one go into self-oscillation at
full power, typically at a high (inaudible) frequency, 100KHz or so, overrunning the amplifier without
anyone knowing about it until it dies in smoke and flames.
and also this
They have been introduced as a safety precaution if the volume gets turned up
enough to cause clipping, in other words when it starts to distort.
you should remember what you write in previous posts.
Henry
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