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Old 11th August 2015, 01:31 AM   #1
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Default loudness button adjustment on the circuit board?

sorry gentlemen. i surfed the related threads. not for what i need.

model : marantz rs 3555 2ch stereo receiver.

the loudness button is in overdrive. when i turn it on it pounds the speakers. its too loud.

i did find a service manual at
Service Manual RS3555

does anyone have a free service manual DL link or maybe someone could tell me where the loudness on the circuit board is so i can turn it down.

i usually leave the loudness button on with all or most of my past units. is it risking damage to a circuit?
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Old 11th August 2015, 03:46 AM   #2
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Sorry that I can't assist with docs. Nor with board layout, other than to suggest tracing back from the switch. But I am curious. Is this a malfunction or has the receiver's loudness always worked this way?
It's probably not harmful to circuitry, but your speakers are better off without it.
A loudness function on an amp is actually just a specific kind of tone control, intended to offset peculiarities of human hearing at lower SPLs. You could modify the gain set in the loudness circuit, though you might be well-served by incorporating an equalizer into your system (2 bands per channel or 12, I'm speaking very broadly here).
Speaking of... Is there a bass tone control you can back off to reduce the loudness effect?
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Old 11th August 2015, 05:52 AM   #3
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Originally Posted by sofaspud View Post
Sorry that I can't assist with docs. Nor with board layout, other than to suggest tracing back from the switch. But I am curious. Is this a malfunction or has the receiver's loudness always worked this way?
It's probably not harmful to circuitry, but your speakers are better off without it.
A loudness function on an amp is actually just a specific kind of tone control, intended to offset peculiarities of human hearing at lower SPLs. You could modify the gain set in the loudness circuit, though you might be well-served by incorporating an equalizer into your system (2 bands per channel or 12, I'm speaking very broadly here).
Speaking of... Is there a bass tone control you can back off to reduce the loudness effect?
SS>>>>>>is this a malfunction or has the receiver's loudness always worked this way?
chuck>>>>>i bought it from a friend awhile back at a nice price. it seemed to work ok. got it out of the box and hooked it up to my 3way floor speakers with 12gauge speaker wire. maybe someone was in there and changed some of the controls on the circuit board. it should be ok from the factory. other than the overdriven loudness button it seems to be ok.

SS>>>>>wont hurt the circuits but speakers are better off without the loudness.
chuck>>>>>i have had quite a few receivers and they did not do this with loudness on. im using 12 gauge speaker wire. is it possible the bigger speaker wire might do this on a more powerful amps?

SS>>>>>Is there a bass tone control you can back off to reduce the loudness effect?[/QUOTE]
chuck>>>>>it has the bass, treble, no midrange and loudness button. with loudness on at about 1/3 volume when listening to music i need to turn the bass control way down to almost minimum or the speakers will have a little too much bass. with loudness off i need to turn the bass control up to at least 3/4 or maybe on full to get some bass. loudness function seems to be overdriven or loudness off needs to be adjusted. maybe both. not sure where to go with this. a decent EQ will be a little pricey.

heres a pic from the web
Marantz RS 3555 Receiver (Century) Photo #452083 - US Audio Mart
its in real nice condition and has plenty of power.
hold control down ctrl on KB and press + to magnify to see the front and back panel pics better.
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Old 11th August 2015, 11:20 AM   #4
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The problem isn't with 12awg wire. It looks to me like the issues are more likely to originate with the speakers, source material, and/or listening preference.
Probably not what you want to hear.
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Old 11th August 2015, 03:49 PM   #5
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Originally Posted by sofaspud View Post
The problem isn't with 12awg wire. It looks to me like the issues are more likely to originate with the speakers, source material, and/or listening preference.
Probably not what you want to hear.

chuck>>>>>the speakers are original from the maker.
2 cerwin vega dx-9 4ohm https://www.google.com/webhp?sourcei...vega+dx-9+pics

do the wizards here think it is possible to make changes to the loudness on/off on the circuit board? its weak with loudness off then overdriven with loudness on. bass control on low when loudness on and bass on high when off.
any ideas.
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Old 11th August 2015, 06:59 PM   #6
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Originally Posted by chucklp61 View Post
do the wizards here think it is possible to make changes to the loudness on/off on the circuit board? its weak with loudness off then overdriven with loudness on. bass control on low when loudness on and bass on high when off.
any ideas.
Yes. You could probably do it with one resistor per channel. You might have to cut a trace. Or you might be able to just change the value of one resistor in each channel.

I did not look at your service manual link, but maybe you could look at it and figure out what I'm talking about. Or maybe you could post a picture of the loudness function circuit and then you'd probably get more help.

One size fits all loudness rarely works well. Its effect is directly affected by the efficiency of the speakers; too much efficiency = too much compensation. I'm a fan of loudness compensation, but it has to be variable. Less is always better to me.

Last edited by Fast Eddie D; 11th August 2015 at 07:01 PM.
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Old 11th August 2015, 07:11 PM   #7
rayma is offline rayma  United States
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Quote:
Originally Posted by chucklp61 View Post
its weak with loudness off then overdriven with loudness on. bass control on low
when loudness on and bass on high when off.
Try setting all the tone and loudness controls to flat, and reposition your speakers for the best bass response.
This can make a big difference. Use stands (or try a different height of stands) to raise them off the floor,
and also try moving them farther or closer to the rear wall. If one or both of the speakers are in a room corner,
move them inward a couple of feet.
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Old 11th August 2015, 07:19 PM   #8
sreten is offline sreten  United Kingdom
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Hi,

The loudness function needs to be aligned with speaker efficiency.
It will be OTT if set up for low efficiency with high efficiency speakers.
If so its best ignored, adjust bass levels as you adjust volume.

rgds, sreten.
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Old 12th August 2015, 02:48 AM   #9
anatech is offline anatech  Canada
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Hi chucklp61,
Both sreten and rayma have given you the best advice so far. Turn the loudness off and leave it that way. Reposition the speakers and maybe add a little bass. Many folks find that is sounds better set flat with no loudness as long as the speakers and room are up to your standards. Small rooms can sound boxy with low bass notes as the volume of air will not support the lower notes. So it is possible that physics is against you as well.

If you start messing around in there you may soon need to see a person like me (audio service tech). There are no adjustments for loudness, but rather fixed resistors and capacitors. This circuit works along with the loudness tap on the volume control. My crystal ball has clouded over if your future runs in that direction.

-Chris
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Old 12th August 2015, 07:51 AM   #10
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Originally Posted by sreten View Post
Hi,

The loudness function needs to be aligned with speaker efficiency.
Yes. Rarely does a semi-random combination of receiver and speakers provide acceptable loudness compensation.

Many commercial designs of yesteryear incorporated variable loudness controls. There are various schemes but the one I like the best is in the Nakamichi TA series receivers. I prototyped a circuit based on that topology and I will definitely incorporate it into my next preamp. All it requires to work properly is simple buffering.

Another source of bass deficiency is baffle stop loss, which can theoretically amount to 6 dB but is almost never that much. Baffle stop loss is best addressed by speaker placement, although there are some simple circuits that will address it. A simple buffered baffle stop compensation circuit will be incorporated into my next preamp but the controls will be located on the back, away from monkey hands.

Last edited by Fast Eddie D; 12th August 2015 at 07:58 AM.
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