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Old 1st December 2006, 02:40 PM   #1
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Default cd input too loud can it be attenuated?

Hi everyone can i attenuate the signal to the inputs on my Sony Taf 540 e amp,the volume control goes around fully twice,however it is still too loud i know you can attenuate speakers with resistors in series and across loads,vcan this be done with line level signals,if so any resistor values would be great

Thanks in advance
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Old 1st December 2006, 03:24 PM   #2
Spev is offline Spev  United Kingdom
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yes you can - I've attenuated different inputs to different levels on my amp - one has 10k series/10k to ground, the other has 20k series/10k ground which I believe give approx -6db and -10db. It was easy enough on mine as the rca sockets have flying leads to the pcb, rather than being attached directly to pcb...
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Old 1st December 2006, 05:36 PM   #3
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Default attenuation

Hi spev many thanks for reply,i am also going to look at the volume more closely also as you can quietly hear the sound when on minimum,i have a few rca sockets lying around so ill try 10k series 10k to ground and 20k series 10k to ground,

When this particular amp is working it is very impressive in detail and absolute power due to design,but the volume when turned down has a little bit of play ,gonna get me parts boards out a try your suggested values.cheers
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Old 1st December 2006, 06:22 PM   #4
AndrewT is offline AndrewT  Scotland
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Hi,
using a source resistance as high as 10k or 20k will kill all the treble, if your amp has the usual RF filter at the input.

Give us more details and we may be able to help.
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Old 1st December 2006, 06:39 PM   #5
sreten is offline sreten  United Kingdom
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Hi,

sounds drastic but the ratio you need is more like 10:1.

I built 8:1 attenuators into new phono plugs on the amp
end of the leads for the CD. 6.8kohm and 1Kohm resistors.

/sreten.
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Old 1st December 2006, 08:25 PM   #6
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Default attenuation

Hi members many thanks for replys i shall remove the volume pot which is at the rear surrounded by metal(sheiding)with a shaft to the front and remove the input board to see whether any filters are around the rca,s ill keep you posted ,,cheers
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Old 2nd December 2006, 04:03 PM   #7
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Default Follow up to cd attenuation

Hi all

This is some more info about cd input too loud

Firstly the volume control was faulty,the end stop iside was broke,drilled four rives took the pot apart(Alps 139c)8 pins but only six used swapped the inner brown box sections of this pot around so now the pot stops and starts where it should success,the pot is supposed to be 120 k x2 but actually is 105 and 108 l and r channel.

All inputs on the board have a 1 meg resistor going from input live to ground that is all .

Yesterday i built two attenuators ie 10 k series 4.7 k to ground,this did nothing to the volume ,but the 10 k series 3.3k to ground had very good results enabling me to swing the volume a lot more gradually instead of the normal move a bit and in your face .

Is it possible that the pot is buggered and needs to be replaced
Dimensions are 18 mm wide 20mm tall 18mm deep i can not find out any info from Alps site or anywhere,

Asimple solution would be a blue velvet but too big as the pot is mounted on a horizontal board which plugs into the vertical input board,also the pot shaft is not completely circular it has a chamfred face and fits into a coupler which connects to a long aluminum shaft.

I am happy with the latter attenuator i built however it has been noted that this could affect the top end

Any info would be greatly considered

Thanks in advance
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Old 4th December 2006, 11:02 AM   #8
sreten is offline sreten  United Kingdom
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Default Re: Follow up to cd attenuation

Quote:
Originally posted by homertooties


Yesterday i built two attenuators ie 10 k series 4.7 k to ground,this did nothing to the volume ,but the 10 k series 3.3k to ground had very good results enabling me to swing the volume a lot more gradually instead of the normal move a bit and in your face .

Is it possible that the pot is buggered and needs to be replaced
Dimensions are 18 mm wide 20mm tall 18mm deep i can not find out any info from Alps site or anywhere,


Thanks in advance
Hi,

The first attenuator should have done somethng to the volume.

If your pot is fine on other sources there is nothing wrong with it.

You need 10K series, 2k to 1k to ground for the CD input.

Treble will not roll-off if done at the amplifier end of the lead.

/sreten.
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Old 4th December 2006, 12:44 PM   #9
AndrewT is offline AndrewT  Scotland
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Treble will roll off if the source impedance rises into the RF filter on the front end of the amplifier.
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Old 4th December 2006, 01:38 PM   #10
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by AndrewT
Treble will roll off if the source impedance rises into the RF filter on the front end of the amplifier.
with a maximum of ~ 2k to ~1k with suggested values it won't, /sreten.
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