The Workbench

Re: Beo Master 7000

tournedos — Sun, 10 May 2009 05:48:00 GMT

Great, just when this thread had cooled down I now have time to post

I did this modification (removed the four caps) on my Beomaster 6500 some months ago (as I posted, and got away with surprisingly little general interest). I find the above commentary from a B&O tech ("no influence on sound") a little odd, since even me with my wooden ears and the half an hour or so between before-after could notice the change immediately. Of course the right way to compare would be to do one channel at a time, but I couldn't be bothered. Well, maybe it didn't have much effect when all the rest of the machine was new and all components performing to factory specs. It would be interesting to simulate it, but I believe the circuit is far too complex for PSpice or similar to get any results that are comparable to real world regarding these caps.

Since Beomaster 5000's and many of 5500's have managed to survive without these caps, I don't believe that they are that critical for normal operation. I would expect them to prevent stability problems when the load of the power amps gets funky, i.e with very long speaker cables, or multiroom setups with passive speakers.

Nevertheless, I plan to improve the preamp stages sometime later, and I will probably put these power amp caps back, just smaller in value.

Re: Beo Master 7000

Dillen — Fri, 08 May 2009 07:14:39 GMT

Yes, and then maybe mount MKS instead of polyester.
Polyester caps are generally reliable components and not the first to
suspect of faults but I have seen tired ones, some that were open circuit, ohmic
or even shorted.

Martin

Re: Beo Master 7000

Die_Bogener — Fri, 08 May 2009 06:15:49 GMT

Passive Pentas have no protection circuits, there is just the crossover in the socket, nothing else.

Active Beolab Pentas have a protection circuit in the amp of course. But if Henrykin used active Pentas, the modification of the BM amplifier would make no sense, he would not hear it because it wouldn't be used. So he must have used passive Pentas for this test.

I think, the modification can make sense and could improve the sound. The next BM7000 will be tested ;)

BUT: i would not remove them completely, i would just make them smaller... not 220nF like orignal, i think 100nF or 150nF would also work.

Sound tuning ist something like black art, it has also something to do wether you believe in or not.

Re: Beo Master 7000

Medogsfat — Fri, 08 May 2009 03:00:53 GMT

Dillen:

Paddy or henrykin (or both ),
As far as I remember there are no speaker safety circuits in passive Penta's (read: Pentas - I'm one of
the misspellers) but I could be wrong, that happens often.
None in active's crossovers either if my fading memory serves me right. However, I'm sure
someone will come along very soon and correct me again.

Martin

No, you're right Martin

My passive Penta's don't have safety protection circuits - I suppose the previous owner could have done a modification & removed them to improve the sound?

Chris.

Re: Beo Master 7000

birgerbum — Thu, 07 May 2009 20:14:55 GMT

Hi Henry

Are we children ore grown up's I just wonder

regards

jan

Re: Beo Master 7000

Jandyt — Thu, 07 May 2009 19:37:43 GMT

Misspelt is often misspelt too.

Re: Beo Master 7000

Dillen — Thu, 07 May 2009 16:03:30 GMT

Paddy or henrykin (or both ),
As far as I remember there are no speaker safety circuits in passive Penta's (read: Pentas - I'm one of
the misspellers) but I could be wrong, that happens often.
None in active's crossovers either if my fading memory serves me right. However, I'm sure
someone will come along very soon and correct me again.

Martin

Re: Beo Master 7000

burantek — Thu, 07 May 2009 15:59:34 GMT

Re: Beo Master 7000

Peter — Thu, 07 May 2009 15:52:27 GMT

A little known fact is that moderators can see the IP address of all posts on any thread.....

Not a lot of people know that.

Re: Beo Master 7000

paddy — Thu, 07 May 2009 15:39:24 GMT

What a coincidence , I don't know the man

never had any contact with anyone on this site.

I have been browsing for a while and came across this post

thought I'd like to post so I did. You do know that probably

is one of the most common misspelt words in the English language.

Paddy

Re: Beo Master 7000

burantek — Thu, 07 May 2009 15:11:51 GMT

paddy:

I'd probabley feel like that in his position.

Paddy

well, it is a free world...

BTW, you spell "probabley" the same as henry...

Re: Beo Master 7000

paddy — Thu, 07 May 2009 14:41:31 GMT

I feel that you have not given henrykin's post that much thought

if you read all his post's you will see that he is using penta's

which have there own protection built in so what he has done

I would say it is perfectly safe for him. Henrykin is quite right

when he say's it is up to the owner. He is happy with what he has done

so everyone should be pleased that he has achieved what he was looking for.

I have not seen anywhere him saying that you should all now try it, just what he did.

Some of the replys seemed sarcastic and I understand why Henrykin seemed so defensive.

I'd probabley feel like that in his position.

Paddy

Re: Beo Master 7000

henrykin — Tue, 05 May 2009 09:16:36 GMT

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

Re: Beo Master 7000

Medogsfat — Tue, 05 May 2009 09:00:46 GMT

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.

Re: Beo Master 7000

henrykin — Tue, 05 May 2009 07:04:19 GMT

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.