Lack of gain?

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I have asked this question in the loudspeakers section but will more likely find an answer here.

I am currently using a VBIGC, full details of which can be found HERE

I am sure that when I first used this amp, I could only use the first few positons on the volume control but now I need to have the volume control at nearly maximum for normal listening.

Yesterday, I put in some EQ for my open baffle speakers and found that I could hardly get any volume at all.

An externally hosted image should be here but it was not working when we last tested it.


Has anybody any ideas what has happened. The mystery is all the more puzzling as both channels are exactly the same!
 
Nuuk said:
I have asked this question in the loudspeakers section but will more likely find an answer here.

I am currently using a VBIGC, full details of which can be found HERE

I am sure that when I first used this amp, I could only use the first few positons on the volume control but now I need to have the volume control at nearly maximum for normal listening.

Yesterday, I put in some EQ for my open baffle speakers and found that I could hardly get any volume at all.

An externally hosted image should be here but it was not working when we last tested it.


Has anybody any ideas what has happened. The mystery is all the more puzzling as both channels are exactly the same!

first of all. Your 220nF across 9.1K make a lowpass filter. Wich starts to attenuates the signal 6dB/octave from 80Hz up to 13KHz where the attenuating start to flatten out at -47dB
 
Konnichiwa,

Nuuk said:
Yesterday, I put in some EQ for my open baffle speakers and found that I could hardly get any volume at all.

An externally hosted image should be here but it was not working when we last tested it.


Has anybody any ideas what has happened.

You MESSED UP my instructions. The 220nF Cap and 9k1 Resistor are siupposed to be in SERIES, not parallel.

Sayonara
 
The cap AND the resistor.

I'm confused now (what's new;) ) This is what T said:

Resistor in series with signal = 12k
Resistor in series with capacitor to ground = 9K1 & 0.22uF

For a little treble lift try a 1nF Capacitor (or larger/smaller to taste) in parallel with the 12k Resistor.

The 9K1 resistor is already going to ground so I only need to move the 0.22uF cap in series with it rather than parallel - don't I?

Or is the 9K1 in series with the 12K?
 
Konnichiwa,

Nuuk said:
OK - I now have a bit more bass BUT to me it seems as though the timing has been affected in the process!

Could this be a correct observation or a trick caused by the bass being a bit more prominent. The music just seems to have lost the speed it had before.

I would think the observation correct. The so called "speed" with certain speakers is almst allways an overly prominent midrange. Bring the bass in line and things get "slow" (I'd say normal). The little filter I suggested was just a quick test to show you a certain degree of what you can expect from equalising the system.

BTW, adding a suitable subwoofer will "slow down" the sytem as well, even a "horn" or "URPS" one....

Sayonara
 
The so called "speed" with certain speakers is almst allways an overly prominent midrange. Bring the bass in line and things get "slow" (I'd say normal)

And so the old 'compromise' issue rears its ugly head again!

I have noticed that 'speed' effect has decreased as I get more used to it. I mention this as it is not a good thing to pass final judgement on one or two hours listening.

And another point, some CD's sound better and others worse. I suppose that being single, I could have two or three systems in different rooms for the various types of music I listen to! ;)

BTW T, is it OK to play around with the values in that EQ circuit (within limits of course!)?
 
Kuei Yang Wang said:
I would think the observation correct. The so called "speed" with certain speakers is almst allways an overly prominent midrange. Bring the bass in line and things get "slow" (I'd say normal). The little filter I suggested was just a quick test to show you a certain degree of what you can expect from equalising the system.

BTW, adding a suitable subwoofer will "slow down" the sytem as well, even a "horn" or "URPS" one....

The term speed seems strange, but you put it within quotes
so I suppose you don't find it quite appropriate. I think I get
what you mean, but just to check if I do. Are you saying that
"high speed" is when the fundamental of a bass tone is too
attenauted wrt. to the harmonics, so we get an exaggerated
spectrum of high harmonics, giving too sharp transients??
That would make a lot of sense to why those smallish toy
speakers everybody buys nowadays seem to have bass
but yet sound so hard and wrong.
 
Christer, I think that T and I are talking of the same thing when we talk of 'speed' so let me answer. It is the timing of the music overall rather than just the 'speed' of the bass.

With more bass, the impression of timing (of the music) is that it slows down. With less the music seems to speed up.

An example. Many people liked the Linn Kann loudspeaker because it appeared to give a very 'fast' foot-tapping presentation which it did at the expense of deeper bass reproduction.
 
I like "fast sound". I guess to each his own? I like horns with fast drivers but lets face it, horns are complicated, BIG,and sometimes very room dependant.At one time i was into OBs and may go back just because of the simplicity and totally un colored
sound.
ron
 
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