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I have had a hard time finding out just *how* interchangeable these tubes are: Can a 5ar4/GZ34 be replaced directly with either a CV378/GZ37 OR a 5R4GY? I have seen that they are all full-wave rectifier tubes, and that they share the same base and pinouts (I think), but they do carry different ratings....How do I determine whether any changes would need to be made to my Dynaco ST70 clone (modded) if I wanted to use either of these tubes? What risks do I run if I just plug em in and go? This type of rolling seems much less clear-cut to me than simply trying different 12at7's or el34's....
Can anyone enlighten me?
Follow Ups:
The 5AR4 and the GZ 37 are controlled turn on types, where no B+ will flow for a ceertain time period (11 seconds IIRC). The 5R4 has a higher plate impedance so will drop the B+ voltage a bit (~40 volts) and does not have a controlled turn on characteristic.
There's been lots of discussion on this in the past.
I use the 5R4's to lower the B+ on original ST 70's where the B+ voltage exceeds the capacitor ratings. Cheap, easy and quickly reversible.
Thank you for your assistance, sir. Where can I go to digest all this information? Any pointers?
...under "look for text" here. IIRC, there is a fairly strong consensus that the GZ34/5AR4 is really the only suitable rectifier for the (stock) ST-70. But take a look.
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