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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Sun SV2a3 or 45?

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At a crossroads. When upgrading my power tubes on my Sun Audio SV2a3, should I switch to type 45 tubes (have the stuff I need to make this circuit change), or plug-n-play with 2a3's?
Will be using speakers rated >96db in 20'x14' room. Looking to improve dynamics. Upgrading tubes, speaker drivers, phono cart, etc. with this in mind.
Musical preferences are that of timbrel and harmonic richness and an involving and dynamic soundstage over accuracy and an extended flat frequency response.
 
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At a crossroads. When upgrading my power tubes on my Sun Audio SV2a3, should I switch to type 45 tubes (have the stuff I need to make this circuit change), or plug-n-play with 2a3's?
Will be using speakers rated >96db in 20'x14' room. Looking to improve dynamics. Upgrading tubes, speaker drivers, phono cart, etc. with this in mind.
Musical preferences are that of timbrel and harmonic richness and an involving and dynamic soundstage over accuracy and an extended flat frequency response.

You will get less than half Pout with the 45 in comparison to the 2A3 and distortion would not be necessarily lower. The reasons are:
1) the SV2A3 front-end hasn't got enough supply voltage to swing more than 45V peak with reasonable distortion. It is already at the limit with the 2A3!
2) the OPT is not ideal for the 45 having 2.5K and 3.5K primary impedances. 5K is better and the Tamura F-475 would be ideal for the 45.

If you want to try anyway with 3.5K load you need to change the 750R cathode resistor. It should be around 1.5K for the 45.
 
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