different audio forum

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jimmyjoe

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Joined 2005
" .... You can also try the ancient tripath 2020 board. I have one and it runs everyday for TV speakers for 10 years now. It's real 10 watts and I paid 10 $ and used a leftover 12 volt 2A PSU ..."

I've heard of those. I think someone here in town still has one of them. I'll look into it.

" ... Your AE Aegis speakers have a claimed sensitivity of 90dB, so will go loud with just a couple of watts of audio power. So, very suited to a low power battery operated amplifier! ... "

Thank you, Galu. BTW ... what do the "l" and the "u" stand for in "Galu"? I already know what the "Ga" stands for; Guardian Angel. :) :) Thanks. jj
 
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jimmyjoe

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Joined 2005
Looking at those small amps (and others) made me think of something. Usually, speaker designs use a resistor on the tweeter to bring it down to an acceptable level. There have been opinions here and there that this causes a lack of transient response, or high frequency purity, or whatever. The general consensus is that if the tweeter could be run without a resistor, then that would be better.
Why not use one of these amps, installed so that one amp is installed on each driver, and then use the "volume" control to match levels correctly? And I'm talking about a volume control, not a gain control .... if there's actually a difference.
Wouldn't this be better? Thanks. jj
 
Galu

Galu

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Joined 2018
jimmyjoe said:
I'm talking about a volume control, not a gain control .... if there's actually a difference.
Click to expand...
Sometimes 'gain' is just another word for 'volume', but let's take a look at a guitar amp where we can clearly express a difference.

The setting of the 'gain' control determines the level of the signal going into the amp i.e. the loudness before amplification.

The setting of the 'volume' control determines the level of the signal coming out of the amp i.e. the loudness after amplification.

The guitarist can turn up the gain control, overload the amp, then keep the volume reasonably quiet with the volume control. That's how guitar distortion was created!
 
Galu

Galu

Member
Joined 2018
Gain stages amplify the signal. An attenuator before a gain stage acts as a 'gain' control and an attenuator after a gain stage acts as a 'volume 'control.

The purpose of a gain control is to tune the amp’s input stage to accept the incoming signal voltage level. Set too low and background noise takes over. Set too high and the result is distortion.

The gain of a stage is usually fixed, but varying NFB as in your case will alter the gain of the stage (as well as altering bandwidth and distortion).
 
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awkwardbydesign

Member
Joined 2005
I guess I was being pedantic. But in my head I do separate input attenuation and the gain (multiplication factor) of a stage, as it makes it easier for me to understand what I am doing. Not much easier, but every little helps!
One of my DHT pre-amps has a potentiometer on the input, but I leave that wide open and use a TVC on the output, as that reduces hum and noise along with the volume. I just have to be careful, as you point out, that I don't overload it.
 
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jimmyjoe

Member
Joined 2005
Okay .... another stupid question. In other words, I've tried to read up on this subject, and don't understand this relationship.
How are inductance and hysteresis related? Does increasing inductance cause hysteresis? Or is it CAUSED BY hysteresis?
The reason I ask is that I'm trying to understand the performance of the A26RE4 woofer in the SEAS A26 kit system. Thirty to forty years ago, there were woofer designs that produced high frequency rolloff very similar to this ..... and they sounded like garbage. Although improvements have undoubtedly occurred from then to now, I've heard (anecdotally) that the A26 kit sounds a bit muffled, or a little lacking in the "dynamics" department. I haven't heard the kit myself, nor are there any close around me to audition.
Is there a relationship to these two properties? And do either one of them apply to the A26 kit? Thank you. jj
 
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