henrykin:

Sorry if I appeared rude.

Don't worry about it,  we all want the same - that you enjoy and get the best from your B&O

I'm trying things out of curiosty. The mod seems to have worked for the

quality of sound now I'm trying to improve on the volume at low end.

It's now become an addiction.

I'll probabley be dead and buried by the time this is sorted. LOL

What else I find crazy it comes with a connection for a graphic equlizer

and B & O don't do one.

If anyone has any info on upgrading the preamp thats in it I'd be grateful

Sorry everyone I got this mod from beo central not the workbench

sorry everyone for misleading info.

http://notebook.beocentral.com/beomaster-5500-6500-and-7000/

Just to keep you all informed my amp is still working

with no problems. From last friday

Good !
Perfectly safe to remove those caps then. Sorry that I raised doubt.
Stupid guys to add them in the first place, what were they thinking ? 

Martin

Thankyou.

Die_Bogener

wrote 

Can someone please post a link to Die_Bogener's write-up on upgrading the BM5500, 6500, and 7000 preamp?

Thanks much,

Aaron

http://forum.beoworld.org/forums/t/2085.aspx

Henry

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

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

Peace my friend, we only have this one planet.
I merely recommended a different mod and told you what B&O's answer was.
Neither of us told you it would distort and I don't say it WILL go up in smoke.
Please understand 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."

- Was said by B&O. Not me !
But it partly confirmed my guess at the caps function.
Apart from that, the amplifier WILL distort if cranked up too high.
Any well-proportioned amp will.
The difference being the way it distorts. This way is called soft-clipping and is
here to protect your tweeters rather than the amplifier since clipping causes a high
amount of harmonics (edgy and sharp curveforms with huge amounts of energy).

"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."

- Was a question based on (more than 30 years of) experience with (not just) B&O and
based on the fact that I sat down with the schematics and tech info sheets and asked myself why those
caps were introduced in the first place.

There's no way I can tell you it WILL go wrong. Clearly, lots of owners would
have had this problem if that was the case.

Clearly neither you, nor the experienced B&O tech guy you spoke to, have had
enough Beomasters of this type on the bench to know when an amplifier has burned
for "no apparent reason".
I have only limited experience with this "somewhat new" B&O thing the Beomaster 5500 is
but out of the maybe 70 or 80 Beomaster 5500 units I've seen, I think, 4 or
5 cases of "mystic blows" of which at least 2 or 3 was beyond economic repairs.
Neither of these had the caps mounted.
I never saw a "mystic blow" in a Beomaster 5500 that had the caps, all faults
in these could be explained otherwise. (Mainly cracked solders, idle current
runaways, driver or speaker shorts, electrolytic leaks etc.).
Yours may work fine for years.

"you should remember what you write in previous posts."

- ...
I'm lost for words so I'll just shut up. I know nothing about electronics and if you need advice or help
I suggest you ask an experienced guy (=someone else). 

Martin

OK peace we will agree to disagree.

End of

Regards Henry

Martin

I'm lost for words so I'll just shut up. I know nothing about electronics and if you need advice or help
I suggest you ask an experienced guy (=someone else). 

Not once did I imply that you know nothing

Your knowledge and imput is as valuable as anyone elses and I wouldn't hesitate to ask

you for help and I also would like to think you would tell me I was saying something wrong

Just because I didn't agree doesn't mean I don't listen.

Sorry if it got a bit over heated

Henry

Martin is one of the most knowledgeable people about B&O that I know. His opinion is highly respected throughout the B&O world. His collection has also been one of the largest. He is a top contributor both here and on Beocentral where he has donated many superb pictures from his own collection. The modification to the 5500 was indeed made because of instabilities, particularly in multi-room set ups. I have two 5500s - my main one has the capacitors in place - the other one has had them removed. I actually detect little difference with CX speakers - more with RLs. I will not be changing my 7000 though or indeed the other 5500. If Martin says they are there for a reason, that is good enough for me. I am sure that removing them will have an effect - but it would appear that the effect is both good and bad. I think therefore that it should be the decision of the owner whether to take the risk.

Peter

I totally agree with you Martin has vast knowledge

and it is up to the owner what they do.

It was a clash of ideas thats all nothing more nothing less.

Henry

I'll be deleting my acount tomorrow. martin So your littie click can stick together.

Eh?  Where did that come from?

I've just read this thread, twice - and i thought it was informative, fair and balanced. If we all agreed about everything, the forum would be dull - but when it comes to 'black and white' tech specs i assume it's less of a grey area than a simple opinion, surely?

Anyway - i don't see any 'clicks' here - only people trying to help and offer their advice/knowledge...  Sorry you feel that way.

Lee

I took your advice I have just come back from an electronics shop I took the mod that you recommended  and asked what he thought and his opinion was it's beyond the extreme. I would not attempt it.  The man has been in the shop from school and his father before him.

henrykin:

I took your advice I have just come back from an electronics shop I took the mod that you recommended  and asked what he thought and his opinion was it's beyond the extreme. I would not attempt it.  The man has been in the shop from school and his father before him.

Are you referring to member Die Bogener's (also called Martin) modification here?

If so, it isn't THAT complicated and I certainly wouldn't rate it as being "beyond the extreme"

Chris.

I am but I was not slating it. I looked at the mod at the suggetion of

Dillen  and took his advice to ask elsewhere. Thats all