Saturday, July 9, 2022

SRPP SE2A3 Circuit Redux

Back in the late 90s, I dismissed the hi-mu/low-gm SRPP input/driver because I found that the circuit had a tendency to sound tiring over extended listening. However, my memorable encounter with the Morikawa SE2A3 amp owned by my buddy Jose was haunting. I had to revisit this circuit just to make sure I left no stones unturned. 

Earlier this year, Steve of Angela Instruments shipped me the "shop mule" SRPP SE2A3 amp for a check up. After replacing the leaky coupling caps, the amp was as good as when I delivered it to the shop over two decades ago.  

My hotter operating point = slightly more power compared to Prof. Morikawa's SRPP 2A3 amp.

!!!WARNING!!! 

The voltages in this circuit are potentially lethal! Build at your own risk!

Click here if you'd like to try the SRPP 45 triode circuit.

Use a Hammond 302AX power transformer instead of T1 + T2 A&B


Click here to see the "cleaner" 10kHz square wave from the Morikawa SE2A3 amp

In spite of the 10 kHz square wave spike from the budget Hammond 125ESE output transformers, it was a very refreshing musical reunion with the Angela SRPP 2A3 amp. 

During its residency in the man cave, the amp powered my back up Altec 2-way system above, Altec 755As and Altec 755Cs in Silbatone cabs below. It was totally devoid of the listener fatigue I previously ascribed to the circuit. Even with the brightest and harshest software and/or hardware thrown into the listening chain, I couldn't induce the unpleasant quality which bothered me in the past. 

Then it dawned on me that I started doubting the SRPP's musical abilities when my Altec 2-way project commenced. Sorry SRPP, it wasn't your fault...😟


YMMV!😉






6 comments:

  1. Good to see SRPP 2A3 amps back on the jelabs recommended list! Now I can take my Rankin SRPP 2A3 amp (Baby Ongaku design from Sound Practices) and give it another listen with a clear conscious :-).

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  2. I built your simple 45 and enjoying it ver much. Have some transformers and parts laying around so thinking of building the srpp 45.
    Is the input sensitivity similar between the simple and srpp version?
    Thinking of biamping.

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    Replies
    1. Glad to hear that!

      I haven't measured them in a long time but I'm pretty sure the Simple 45 is ~ 1-1.2Vrms and the SRPP is more sensitive, ~ 0.7Vrms or less.

      I've never been a fan of bi-amping especially mixing the sound of two different amps. IME, the midrange is always compromised.

      But some people have been successful. As long as you enjoy your music, that's what matters most!

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