[longplates]

Hello-- After reading every previous post that I could about RIAA caps, I found two separate one that mentioned using Vitamin Q caps there... and one of the original authors mentioned having asked Jim Hagerman about the minimum voltage rating for these caps. According to the post, the reply came back that with a high quality cap like a Vitamin Q PIO, one can go as low as 250 to 300 VDC. My Hyrel Q/Vitamin Q  47nf (for C202)and my WestCap 1f (for C204)are 300VDC. I guess I just need a little hand holding and reassurance that 300VDC caps are going to be OK for the RIAA caps, C202 and C204. Thanks in advance for your time!

[longplates]

Sorry-- that should read (obviously ) 1nf Westcap/300VDC I have for C204.  Thanks again!

[hagtech]

No problem.  You can even push 200V without much worry.  The only issue is when a tube completely fails (or if not installed), the voltage can go up to 300V. 

jh

[poty]

...the voltage can go up to 300V. 

... or even higher. There are already the voltage margins allowing the voltages on C201 be 5-10% higher (315-330V) than marked/counted - the voltage will be in full value across C202-C203 if the V200 failed and across C204 if V201 failed. The second source of the rising is unregulated B+. If any of tubes failed the current to the stage will be lowered, so drop of the voltage across R221-R220 will be lowered too. B+ will rise accordingly. Counting from the values marked on the manual, each channel draw 7mA, so there is normally 25.2V across R220-R221. If, for example, V202 dies then the current must be only 1mA, across R220-R221 - 3,6V, difference +21.6V. In fact the voltage jumps even higher as soon as the less current - the less losses in T100+R101-R102+V100.

[longplates]

Thanks so much for the assistance! Those Hyrel Q 47nf caps and WestCap USA NOS 1nf paper-in-oils should be superb, sonically. Thanks again to Jim Hagerman and to Poty for taking the time to respond to my questions, and to provide additional info to me concerning scenarios for undesirable voltage rise in the face of V200 or V201 tube failure. I appreciate the information.  The willingness of extremely knowledgeable forum members as well as Jim Hagerman himself to assist newbies like myself is one of the many great things about this forum! Thanks again.