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Old 15th May 2003, 12:28 PM   #1
Mad_K is offline Mad_K  Norway
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Default Gainclone with pseudo-balanced input?

-Wouldn't this balance the impedances, so that I can use my BZLS to drive a gainclone?
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Old 15th May 2003, 02:30 PM   #2
protos is offline protos  Greece
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This works for me.
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Old 15th May 2003, 04:25 PM   #3
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This works for me (though I drive it from an unbalanced source).

<center>
<img src="http://www.q-audio.com/images/balancedgainclone.jpg">
</center>

se
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Old 15th May 2003, 04:43 PM   #4
Mad_K is offline Mad_K  Norway
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I guess it ("my" drawing) wont work because the out Z of the BZLS will become imbalanced differently on the +/- in...
O, well an excuse to make a bridgeclone then..
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Old 29th May 2003, 09:46 PM   #5
Mad_K is offline Mad_K  Norway
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After having fiddled a little with these bits, I have decided upon a design for my own gainclone. If everything works out (ie the rest of the parts arrive) it'll be finished next week. BTW -I have finally got myself a job as an EE (I finished school 2 years ago!!!
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Old 30th May 2003, 07:56 PM   #6
Mad_K is offline Mad_K  Norway
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Nobody interested? Or is this old news?

-I was just going to say that I have buildt the circuit, and I can only say that it works beyond my wildest expectations
All that, and it is only buildt as a proof of concept-rig with less than optimal components, layout etc. Next week I'll have my finished version up and running, with much better components, wiring, connectors, dual-mono etc. Sad to say really, but it demolishes my aleph30 clone..

BTW, my reason for having balanced input is that I already have a Pass BZLS, that I'm very fond of and I think it's simply MAGIC (-everything it connects to turns to "Aural Gold") . Much better sounding than standard gainclone methinks, but that depends on individual systems i suppose..

This version has lower gain; 20dB (versus 27dB for the original), and a little higher input impedance 22Kohm per phase (or 44Kohm balanced) to make it a better match with my pre. Oh, I forgot to mention -the use of a smd resistor for the feedback is highly recommended. It fits really nice on the opa549

I'll report back with some pictures and listening impression after the final version is done.

BR,
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Old 30th May 2003, 08:29 PM   #7
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Looks good mate, does it sound as good as the original?

I have yet to try SMD resistors, mainly 'cos I know nothing about them. What brand did you use, and how easy was it to solder?

Congrats on the job
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Old 30th May 2003, 09:07 PM   #8
Mad_K is offline Mad_K  Norway
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Quote:
Originally posted by pinkmouse
Looks good mate, does it sound as good as the original?

I have yet to try SMD resistors, mainly 'cos I know nothing about them. What brand did you use, and how easy was it to solder?

Congrats on the job

-In my system it sounds way better than both std. app. note circ, std GC, IGC, minimized GC and every other config I tried. The SMD I used is a std metal film unit made by KOA in 1206 size (3mm) -Real easy to solder; just tin the legs of the OP, put the SMD in place -hold in in place, and touch the leg/resistor for a second and VOILA!

It fits real nice between the pins on the opa549 http://focus.ti.com/docs/prod/produc...tNumber=OPA549
You could even use one size smaller resistor I think (2mm)..
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Old 31st May 2003, 04:07 AM   #9
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Default Balanced GC

Why don't you go have a look at how Marchand does it on their PM21 model? There's a pdf file for it.


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Old 31st May 2003, 07:24 AM   #10
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Hi Mad_K

When you say it sounds way better than IGC you compare the sound of balanced versus non-balanced operation and a whole lot of additional factors like preamp/cabling would affect the way it sounds. It would seem difficult to distinguish whether the chip amp prefers both inputs being driven or whether your external setup sounds better this way.
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