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PostPosted: 16 Oct 2012, 16:54 
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I suppose we must remind ourselves that these amps have a hefty amount of global feedback. My tubes amps don't. I may use a little local feedback as in an un-bipassed cathode resistor on the driver tube or the UL tap from an SE OPT. And as I have said before these chip operate in Class A\B mode where SE amp generally are in Class A only mode.

I have made a number of two stage tube preamps over the years and notice how "subdued" they sound compared to my single tube preamps. Still excellent sounding but not the presents of the the tube preamps without the GNFB.

Another noticeable point with the music is it appears to lack dynamics. Plenty of power just not the feel of drama particularly when compared to Luciano my 807 amp. The chip amps probably do have good dynamics but my tube amps seem to release a more dramatic pesenation. Not so much my 300BSE - Silver Dragon but definitely Luciano.

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PostPosted: 29 Oct 2012, 10:18 
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Nice big build Mark. Where did you find that slab of copper? Very nice. I would also place some shielding between the torroid and the the audio channel.

Cheers

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PostPosted: 29 Oct 2012, 16:58 
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I bought four slabs the same size years ago for another chip amp which never got built but similar idea of resonance and heat control. I wanted to do this compact build and any other heat sink would not really work. I would like to build another exactly the same but on an Al slab to hear the difference (if any). I have golden ears coming around today for an audition. I'll post their thoughts.

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PostPosted: 30 Oct 2012, 06:17 
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I said I would report on what the Golden Ears had to say about the amp.

I'll quote what was said and you interpret as you think:(said to me) "Why do you build tube amps"? I'll take it as a compliment.

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PostPosted: 03 Nov 2012, 06:47 
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I was listening with a another keen DIYer today to the SynergyII\CU amp. He felt it a bit bright and brittle and blamed my Silver Highway silver inter-connects for this bright top-end http://www.diyaudioprojects.com/Power/diySilver/. I use very short wire wrap wire inter-connects from Oppo BDP-95 to BoZSE preamp then Silver Highways to power amp. I swapped the Silver Highways for a pair of Transparent 200s.

Though these commercial cables are\were only $150 a pair they always sound good. Instantly the sound mellowed and the brightness gave way to a warmer sounding and fuller mid-range and the brittleness left us completely. Every track we played from that point felt just fuller and warmer and made the amp sounded more relaxed instead of tense and bright.

I have a number of rolls of cotton coated solid strand hook-up wire which I used for the Fender Champ guitar amp I made. I will make some inter-connects from this wire. I will heavily twist two strands then place a heat shrink tube of the twist. I have some heavy duty earth first RCA plugs to go with it. Let's see if these home made cables will be as good as the Transparent 200s.

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PostPosted: 13 Nov 2012, 07:28 
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If I wanted to reduce the gain on this Gainclone what would be the best way to do it?

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PostPosted: 13 Nov 2012, 07:34 
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Here's one I haven't seen before: http://electronics-diy.com/electronic_schematic.php?id=530. Yet another rip-off.

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PostPosted: 14 Nov 2012, 01:38 
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I'm having some Golden Ear over this evening for an Opera night (Rameau) let you know his impression (or depression if he is not a happy listener). Of course the 4SUTea will be on show too. I'm nervous. Feel a little more confident with the 12AU7 in the Tea box.

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PostPosted: 14 Nov 2012, 23:29 
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mwhouston wrote:
If I wanted to reduce the gain on this Gainclone what would be the best way to do it?

Hi Mark,
You control the gain by adjusting Rf and R3.
Gain = (Rf / R3) + 1.
So in the case of your Synergy Amp: http://diyaudioprojects.com/Chip/Synerg ... Gainclone/

Gain = ( 22000 / 680 ) + 1 = 33 dB

Just increase R3 to lower the gain. 1k for R3 will drop the gain down to 23 dB. You need to keep the gain above 10dB for stability.

Cheers

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PostPosted: 15 Nov 2012, 00:30 
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@Gio: Thanks for the advice. It is actually easier for me to lower Rf. Is this a valid gain reducer?? What about dropping it to 15K for a gain of 23db. Is there a consequence I have not foreseen?

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