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Old 31st July 2003, 12:42 PM   #11
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Quote:
Originally posted by janneman

high-end (read: expensive) speaker cables

I might arrange 5 different pairs of speaker cables connected to a rotary selector. Then, it could give a better opportunity for the amp gain control and, in addtion, another opportunity for an A/B/C/D/E test of the speaker cables. I hope this will help.

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Old 31st July 2003, 12:58 PM   #12
Nuuk is offline Nuuk  United Kingdom
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Quote:
What MAY need to be addressed is the circuit stability with open input for the inverting design.
Oops, sorry for that mistake. I have no electronics training and that is why I asked for some confirmation.

So what is the answer to the question? Would the inverted GC design work in an active system without causing problems with instability?

And what would be the best arrangement? Crossovers in preamp or immediately before IGCs?

PS I'm going out to get run over by a steam-roller so that I don't have such a high profile
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Old 31st July 2003, 01:04 PM   #13
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you need to wear shades with such a bright future.......
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Old 31st July 2003, 01:17 PM   #14
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Quote:
Originally posted by moamps



Longer interconnects are also expensive.

Touché...

Jan Didden
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Old 31st July 2003, 01:22 PM   #15
moamps is offline moamps  Croatia
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Quote:
Originally posted by Nuuk
So what is the answer to the question? Would the inverted GC design work in an active system without causing problems with instability?
Why not? IGC has higher stability than NOINVGC. IMHO.
Because of that, you can place input chinch very close to output terminal. (additional weak NFB, maybe)

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And what would be the best arrangement? Crossovers in preamp or immediately before IGCs?
Second.

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Old 1st August 2003, 11:53 AM   #16
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Konnichiwa,

Quote:
Originally posted by Nuuk

Oops, sorry for that mistake. I have no electronics training and that is why I asked for some confirmation.
Well, as said, the notion of all the stuff on the inverting pin being the feedback path has been promoted previously (not by you), but is is wrong. I suspect you read it before and simply accepted it.

Quote:
Originally posted by Nuuk

So what is the answer to the question? Would the inverted GC design work in an active system without causing problems with instability?
Yup, will work fine. It MAY be prudent to raise the feedback resistor to 330k and to make sure to connect a 22k Resistor across the input. The resulting Amp will be unconditionally stable, even with no input conenction, though the input impedance drops from 10k to 6.8K.

Quote:
Originally posted by Nuuk

And what would be the best arrangement? Crossovers in preamp or immediately before IGCs?
Due to their very nature the IGC circuit can be adapted to operate as inverting (Rauch type) active filter. So if you want, simply place the filters for each band around the LM3875. The input impedance will now of course be all over the place, so the input to the various networks should ideally be buffered.

If the Filter Circuits are only supposed to be 1st order this is even easier. So I would always have the filters at or around the IGC. Unless I use a commercial external crossover, like the Behringer Digital DCX2496, in which case BTW I would recommend to use pseudo balanced inputs for the Gainclones.

Quote:
Originally posted by Nuuk

PS I'm going out to get run over by a steam-roller so that I don't have such a high profile
I was not refering to your Profile (though truth be told you do contribute a lot).

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Old 1st August 2003, 08:42 PM   #17
Nuuk is offline Nuuk  United Kingdom
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Thanks for the clarification T. It just goes to show, you can't leave us to our own devices and it's a good thing that you monitor these forums on a regular basis

I doubt that I will be using the GCs in an active system as I still prefer the simplicity of using something like the Goodmans 201s but who knows where the holy grail will take any of us next!
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