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GSP Line amps

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Analog Kid View Drop Down
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    Posted: 13 Jan 2010 at 6:05pm
So what can you tell us about the upcoming line amps?
When will they be ready?
What features will they have?
(Tone controls will hopefully be included? Wink)




Edited by Analog Kid - 25 Jan 2010 at 2:01pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Analog Kid Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jan 2010 at 2:01pm
GSP Audio does not want to discuss unannounced products. Cry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jan 2010 at 3:27pm
I'd love to discuss "unannounced products".

But at the moment I'm still unsure what to announce.


Edited by Graham Slee - 16 Feb 2010 at 10:55pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 16 Feb 2010 at 11:11pm
I have been investigating tone controls and still have a way to go.

The last time I did tone controls was on a post production mixer about 17 years ago. I recall they measured "flat" in the mid positions but how "flat"?

Now with the benefit of a simulator, I can see that "flat" can mean a subtle hump, or dip, or even shelving up, or shelving down of the response, where I'd have thought it should be perfectly flat. Obviously the source impedance driving them (buffer stage) and the output impedance of the summing amp (tone control amplifier) they're built around, have a marked effect on this flatness - they influence it, or add to the tone control network impedance.

Here I must add I'm talking about the "Americanized" Baxendall type of tone control - I still have to examine the passive solution.

I did dig out an old Quad 33 tone control circuit for reference and can see exactly why the tone control defeat switch was so important - it would alter the sound simply because in the centre position there is this hump/dip/shelf which could be as much as 1 or more decibels. I am not saying the Quad 33 was a poor design - hats off to the designer! It was good at the time.

My own calculations for a circuit when run exhibited much the same problems. I decided after many hours to take a break from it and then take another look. I will try one or two fixes in the next day or so, and then, if unsuccessful, I will venture down the passive route and report further on my findings.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Analog Kid Quote  Post ReplyReply Direct Link To This Post Posted: 29 Mar 2010 at 11:50pm
Originally posted by Graham Slee Graham Slee wrote:

Now with the benefit of a simulator, I can see that "flat" can mean a subtle hump, or dip, or even shelving up, or shelving down of the response, where I'd have thought it should be perfectly flat. Obviously the source impedance driving them (buffer stage) and the output impedance of the summing amp (tone control amplifier) they're built around, have a marked effect on this flatness - they influence it, or add to the tone control network impedance.unsuccessful, I will venture down the passive route and report further on my findings.


The above need some clarification. Why is flatness a concern with tone controls?
Just by using tone controls to adjust the treble and bass, you are already manipulating
the frequency spectrum of the music, by making the amplifier produce more
or less bass and treble, so common sense would say that flatness is not an issue,
but maybe I misunderstand something.



Edited by Analog Kid - 29 Mar 2010 at 11:51pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote less Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 2010 at 9:02am
Originally posted by Analog Kid Analog Kid wrote:



by making the amplifier produce more or less bass and treble, so common sense would say that flatness is not an issue, but maybe I misunderstand something.


I think AK that what you are missing is that some people may not want to use the tone controls all of the time or at all, therefore any change in the signal defeats that goal.

I have tone controls on my current amplifier but very rarely use them. I was not aware though, until now, that their prescence might still be affecting the signal (Arcam alpha 9 integrated).

Regards

Les
I don't do mediocrity!

Les Sutherland
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 2010 at 1:11pm
Agreed...

If we can show the tone controls result in a flat response when set to their midpoints there should be absolutely no need for a defeat switch - I mean, why have a defeat switch to defeat something that doesn't need defeating?

So why did so many amps need defeat switches?

Exactly! Because the tone controls never had a flat position no matter where they were set!

I don't really like mentioning others but if you model a Quad 33 tone control on a simulator you'll get my drift...

So yet again, the hi-fi industry has gone to silly extremes again to cover up for it's inadequacies. If tone controls are designed properly...

But then again, in defence of Quad, they didn't have simulators in the day of the 33 (so they couldn't have known).
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