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Beomaster 900, high BASS on sound

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This post has 13 Replies | 1 Follower

NickNike
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NickNike Posted: Sun, Apr 23 2017 1:28 AM

Hi, the BASS is very high. It only sounds ok when the BASS turned right off. As soon as any BASS is applied, the sound is thumpy. Is there something I can do to improve this problem? Any particular components that could be the problem?

Thanks

chartz
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chartz replied on Sun, Apr 23 2017 11:25 AM

Even when you turn up the volume?

Jacques

NickNike
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NickNike replied on Sun, Apr 23 2017 2:31 PM

Yes. I turn up the volume so the music is playing normally, but I need to have the BASS knob set to zero. If I turn the BASS knob up it sounds too bassy.

solderon29
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I think you may have to replace the electrolytic capacitors on the main amplifier board.

The tone controls in this design are in the output stage feedback loop,and as the spec of the capacitors go out  as they age,it affects the response of the whole amplifier.

The manual is on site,but can you solder etc?

Regards,

Nick

CB
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CB replied on Sun, Apr 23 2017 4:35 PM
I think I have some soldering to do too!

Plus the right speaker sounds a bit louder...

NickNike
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NickNike replied on Sun, Apr 23 2017 4:37 PM

Thanks. I can solder and I am even the proud owner of a soldering iron  Smile

 

I've looked at the schematics and cannot work this out.

Any chance of a list of part numbers? I take it Dillon can supply the capacitors.

 

cheers

Nick

solderon29
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solderon29 replied on Mon, Apr 24 2017 12:47 PM

I would replace all the blue cased capacitors on the amplifier output board,they are almost sure to be out of spec by now.The unit must be fifty years old,but well worth preserving!

I dare say that Martin has a kit of these capacitors,but they should be readily available,although axial type capacitors are not used much nowaday's

Regards,

Nick.

NickNike
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NickNike replied on Wed, Apr 26 2017 1:31 AM

Hi, Martin says he hasn't any and I can get them off ebay. I can find close replacements but not exact values. Are radial OK to use as opposed to axial?

 

For example, I need

1) 100µF  6.4V
Will 100µF  10V be OK?

2) 4µF  40V
Would 4.7µF  50V be OK?

cheers

Nick

 

Where do I find the manual on this site?

Dillen
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Dillen replied on Wed, Apr 26 2017 6:51 AM

We already discussed that and I already answered that on email - remember?

Manuals are available for download from our main website (minimum silver membership level required).

Martin

 

PS.

This is the second post of yours today that I have had to edit.
Please don't violate posting rules.

NickNike
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NickNike replied on Wed, Apr 26 2017 3:48 PM

Yes, but I have found these much closer values, but cannot find exact matches, so we were discussing something a little different.

Are you saying that if I look hard enough, I should find exact matches? I've looked on ebay, RS and Maplin. RS don't have exact matches and they are a comprehensive supplier.

I'm thinking that standard values may change over 50 years?

I take it I should not post links to other sites?

Sorry, I was just trying to be helpful.

Søren Mexico
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Try here

Collecting Vintage B&O is not a hobby, its a lifestyle.

Dillen
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Dillen replied on Wed, Apr 26 2017 4:28 PM

Nick,

READ MY ANSWERS TO YOUR QUESTIONS!!!
I even suggested the exact part for one of them - and I sent you a link to it!!
(UK Ebay seller - cheaper than I can do it)

Martin

NickNike
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NickNike replied on Wed, Apr 26 2017 4:44 PM

Sorry, I just retraced my messages and found the link you sent. thanks for that. These are 10V, so presumably my idea of being close was OK.

 

That is

100µF 6.4V original
 100µF 10V  closest values found

 

NickNike
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NickNike replied on Wed, Apr 26 2017 5:24 PM

Søren Mexico:

Try here

WOW, what a very useful site.

Many thanks for the link.

 

Nick

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