Slowly but surely I'm becoming more familiar with parts of the sound system and what they do for me.
One of the things I just noticed while looking at the spec's page in the owners manual for my Sharp SM-1122 integrated amplifier is that +10 (full right) on the bass knob adds +8db to the 100hz band. +10 on the treble knob (full right) adds +8db to the 10k band. It doesn't tell me the numerical effect of the loudness button but I bet it is similar to other receivers I've looked at where, iirc, it's just like setting bass and treble to full with the flick of a switch.
I once saw the spec's on my old Pioneer and I think it's treble was farther up the range, like around 16K. Plus the better brands give attenuation slopes and loudness contour figures but, not in this manual.
Now a buddy of mine runs his systems with full bass and loudness on, giving him in effect +20db at 100hz with ported speakers. Muddy sounding AFAIC.
I tend to dink around with OB speakers and really need more attenuation in the 60hz and 30Hz bands over the 100hz band.
Can one change the frequency bands that the bass knob and loudness button affect?
R/
Jim
PS- I'm working with solid state gear for this question.
I think the logical answer would be to go active EQ but I still want to know about changing the bands where attenuation occures.
One of the things I just noticed while looking at the spec's page in the owners manual for my Sharp SM-1122 integrated amplifier is that +10 (full right) on the bass knob adds +8db to the 100hz band. +10 on the treble knob (full right) adds +8db to the 10k band. It doesn't tell me the numerical effect of the loudness button but I bet it is similar to other receivers I've looked at where, iirc, it's just like setting bass and treble to full with the flick of a switch.
I once saw the spec's on my old Pioneer and I think it's treble was farther up the range, like around 16K. Plus the better brands give attenuation slopes and loudness contour figures but, not in this manual.
Now a buddy of mine runs his systems with full bass and loudness on, giving him in effect +20db at 100hz with ported speakers. Muddy sounding AFAIC.
I tend to dink around with OB speakers and really need more attenuation in the 60hz and 30Hz bands over the 100hz band.
Can one change the frequency bands that the bass knob and loudness button affect?
R/
Jim
PS- I'm working with solid state gear for this question.
I think the logical answer would be to go active EQ but I still want to know about changing the bands where attenuation occures.
Sure, I understand that.
But as I said before, if you turn both the treble and bass knobs to 100% or if you hit the loudness button it does the same thing.
I was just wondering if one could change the frequency points that the knobs or button affect.
The amps designers chose 100hz and 10Khz for thier bass and treble points. Could they just as easily choosen 50hz and 15Khz?
R/
Jim
But as I said before, if you turn both the treble and bass knobs to 100% or if you hit the loudness button it does the same thing.
I was just wondering if one could change the frequency points that the knobs or button affect.
The amps designers chose 100hz and 10Khz for thier bass and treble points. Could they just as easily choosen 50hz and 15Khz?
R/
Jim
I believe that most forms of loudness compensation affect the bass only. It's purpose is to boost the bass when listening at low volume and thus restore the balance of the music. Google Fletcher-Munson for a greater understanding of how our ears perceive sound and why loudness buttons came into being.
That being said, the choice of where to put the corner frequencies for bass boost was not arbitrary. It would have been based on the Fletcher Munson curves. That's not to say that everyones ears are the same... you may very well wish to change the frequency or the magnitude of the bass boost.
And yes... this is highly doable... post a schem.
That being said, the choice of where to put the corner frequencies for bass boost was not arbitrary. It would have been based on the Fletcher Munson curves. That's not to say that everyones ears are the same... you may very well wish to change the frequency or the magnitude of the bass boost.
And yes... this is highly doable... post a schem.
A good simple explanation of loudness:
http://www.extron.com/technology/archive.asp?id=loudnesscontrol_ts
Loudness funktion is normally dependant on volume pot position. Low volume max bass-treble boost and then gradually less boost untill max volume when we have no boost at all from loudness circuit.
http://www.extron.com/technology/archive.asp?id=loudnesscontrol_ts
Loudness funktion is normally dependant on volume pot position. Low volume max bass-treble boost and then gradually less boost untill max volume when we have no boost at all from loudness circuit.
Loudness button on decent receivers and preamps follows the Fletcher Munson curve- it scoops out the midrange centered at 3.5kHz.
A few pieces of gear have a continous loudness control where you can dial in the just right amount of compensation.
Also, in some designs turning the volume past a certain point effectively bypasses the loudness circuit.
IMO using loudness button for open baffle compensation is asking for bad results.
Just get a parametric EQ or build a simple 2 opamp circuit that is designed with the correct turnover frequency and gain for your speaker.
A few pieces of gear have a continous loudness control where you can dial in the just right amount of compensation.
Also, in some designs turning the volume past a certain point effectively bypasses the loudness circuit.
IMO using loudness button for open baffle compensation is asking for bad results.
Just get a parametric EQ or build a simple 2 opamp circuit that is designed with the correct turnover frequency and gain for your speaker.
Thanks all so far.
I agree, using loudness in OB is a poor way of doing what's really needed. But it is in experimenting with using the bass knob and the loudness button that started me to wondering what frequencies I was enhancing.
poobah - I have an HP PSC 1610, I'll see about getting a readable copy of the scematic posted.
Please bear in mind, I don't want to mod this amp!
I'm using it as an example because I have the schematic and the spec's available in hand. If I can get them posted then you and I will be looking at the same thing.
Every once and a while on e-Bay someone will post a copy of the owners manual for some super vintage item in thier listing.
Ilove looking at the spec pages now.
I've already noticed differences in the 'corner points' of my Sharp and the old Sansui's and, I assume, my Pioneer SX-450 and SX-780.
R/
Jim
I agree, using loudness in OB is a poor way of doing what's really needed. But it is in experimenting with using the bass knob and the loudness button that started me to wondering what frequencies I was enhancing.
poobah - I have an HP PSC 1610, I'll see about getting a readable copy of the scematic posted.
Please bear in mind, I don't want to mod this amp!
I'm using it as an example because I have the schematic and the spec's available in hand. If I can get them posted then you and I will be looking at the same thing.
Every once and a while on e-Bay someone will post a copy of the owners manual for some super vintage item in thier listing.
Ilove looking at the spec pages now.
I've already noticed differences in the 'corner points' of my Sharp and the old Sansui's and, I assume, my Pioneer SX-450 and SX-780.
R/
Jim
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I checked out 2 pages of Google search on Fletcher-Munson curves. Lot of the same stuff.
I did find one site
http://arts.ucsc.edu/EMS/Music/tech_background/TE-02/AcNumbers/AcNumbers.html
that leads me to believe that the curve most amplifier designers would refer to is either the 60 or 70 db curve.
Those 2 curves are real close in that there is a +6-ish db gain in the 100Hz band over the 1KHz reference band. Read on and you'll see it mentioned “we live in the 60db range, loud music is in the 90db range and we experience pain at around 120db”. Hence my thought that 60-70Hz is where an amp designer would look to optimize his sound shaping tools (buttons and knobs)
I didn’t find anything that says it ‘must’ be the 100Hz band, so I guess my wondering about +8db in the 75Hz band is right in line with the stated curves, I’ve just moved my point 25Hz farther down the scale.
Also, it seems Fletcher-Munson are considered a bit off the mark now (1961 standard ISO 226, rethought in 2003) and Robinson-Dadson is closer to what the curve should be?
R/
Jim
I did find one site
http://arts.ucsc.edu/EMS/Music/tech_background/TE-02/AcNumbers/AcNumbers.html
that leads me to believe that the curve most amplifier designers would refer to is either the 60 or 70 db curve.
Those 2 curves are real close in that there is a +6-ish db gain in the 100Hz band over the 1KHz reference band. Read on and you'll see it mentioned “we live in the 60db range, loud music is in the 90db range and we experience pain at around 120db”. Hence my thought that 60-70Hz is where an amp designer would look to optimize his sound shaping tools (buttons and knobs)
I didn’t find anything that says it ‘must’ be the 100Hz band, so I guess my wondering about +8db in the 75Hz band is right in line with the stated curves, I’ve just moved my point 25Hz farther down the scale.
Also, it seems Fletcher-Munson are considered a bit off the mark now (1961 standard ISO 226, rethought in 2003) and Robinson-Dadson is closer to what the curve should be?
R/
Jim
I guess the next step would be to take the curve corresponding to the level the playback should sound like, and the curve corresponding to the actual playback level, normalise them and plot the difference.
Judging by sight, it appears that this would result primarily in a bass boost.
Thanks 2litre and LineSource for finding the plot.
Judging by sight, it appears that this would result primarily in a bass boost.
Thanks 2litre and LineSource for finding the plot.
I came fairly close by using a two-stage affair, i.e. a volume control with a 10% tap, and also another RC at the low end of the pot. That meant that the volume could not go to zero, but in practice it can be low enough.
For an effort at a close approximation I resorted to a multi contact switch - Elma makes them with 24 contacts, i.e. 47 positions counting the "short" between two contacts as an intermediate step. The steps are small enough not to be really noticable, and obviously one can design to any desired law. I ended with 4 poles in all, but impedances became difficult. I had to drive with 1K.ohm, and load with not less than 1 Meg. In the end I did not include treble compensation; it did not make an audible difference, what with room characteristics etc.
Regards
For an effort at a close approximation I resorted to a multi contact switch - Elma makes them with 24 contacts, i.e. 47 positions counting the "short" between two contacts as an intermediate step. The steps are small enough not to be really noticable, and obviously one can design to any desired law. I ended with 4 poles in all, but impedances became difficult. I had to drive with 1K.ohm, and load with not less than 1 Meg. In the end I did not include treble compensation; it did not make an audible difference, what with room characteristics etc.
Regards
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