Greetings from Salectric

Salectric

Senior Member
Dave Slagle has some Type 50 monos that he brings some years to the Capital Audio Fest. The past couple years he has had his Quad 57s which I guess need more power so the 50 amps stayed home. But at the CAF last weekend he had two rooms, one with the double-Quad panels powered by their built in PP 300B amps, and the other with some cone speakers driven by, I believe, the Type 50s. I had never heard of the speakers before but the amps drove them effortlessly.
 
If you haven’t listened to an all DHT amplification chain, you should try it.....or maybe not!

Todays chain....300b>3b7>45>Altec 605b
 
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Redboy

Knobophobe
@Salectric, a question about your 46 schema...

Why the CCS and the 0D3 gas regulator on the driver tube? Could you get away with using just the 0D3?
 

Salectric

Senior Member
@Salectric, a question about your 46 schema...

Why the CCS and the 0D3 gas regulator on the driver tube? Could you get away with using just the 0D3?
The circuit will work just fine with the OD3 and a dropping resistor in place of the CCS, but it will sound better with the CCS. I experimented with this in a 12b4 linestage. When I first tried the gas tube voltage regulators (I used two gas tubes for the 12b4) I used a dropping resistor and the gas tubes were a modest sonic improvement over the unregulated power supply. But when I added the CCS in place of the resistor the sound quality improved substantially.

While I didn’t try these variations with the 46 amps, I suspect there would be something similar.

A side benefit of the CCS is that it does a great job of filtering ripple in the power supply line. That allows the B+ tap for the 417a to come off the first filter cap rather than the second. I tried it both ways and there was a slight difference in sound quality in favor of using the first cap as the power takeoff point for the 417a.
 

Salectric

Senior Member
WARNING! If you think power supply wiring doesn’t affect sound quality, please don’t read the following.

After using the 46 amps for a while, I was bothered by some minor tonal balance issues. The highs were a tad too bright and the bass was lean, not as warm as I like. Looking under the hood, I noticed the wire connecting the CCS (in the power supply line for the 417a) was a possible suspect. This wire runs from the BlackGate filter cap to the input of the CCS. When I built the amps I used 20g Silver-coated solid copper hookup wire that I bought from Cary Audio many years ago. That wire can sound lean and bright as a signal wire so I wondered if it might be contributing to what I was hearing.

I replaced the Cary wire with Neotech 18g solid copper with Teflon insulation which I have used in power supply wiring in more recent projects. The Neotech wire already had many hours of use in another project.

The Neotech wire pushed the tonal balance in just the right directions: the bass is warmer and and the highs are reduced in level. A side benefit is dynamics are improved as well. To tell the truth the highs are actually reduced a bit more than I would prefer but the overall balance is still much closer to neutral to my ears.

Anyway my only reason for posting all this is to emphasize that everything in a simple amplifier circuit is critical to sound quality. I see that as a virtue in a DIY project because it means that the sound can be tuned to fit a particular system and a particular listener. The folks who buy the latest ARC, CJ or whatever amp don’t have this luxury. If there is something about their new amp they don’t like their only option is to sell it and buy another amp.
 
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