5AR rectifier substitute?

rajacat · « **on:** 14 Jun 2011, 06:28 pm »

Can the more common 5AR4 be substituted for the 5AR? If not are they any other alternatives?

2wo · « **Reply #1 on:** 14 Jun 2011, 09:32 pm »

5AR? Sure you didn't lose a 4...John

rajacat · « **Reply #2 on:** 14 Jun 2011, 10:24 pm »

Quote from: 2wo on 14 Jun 2011, 09:32 pm

5AR? Sure you didn't lose a 4...John

Whoops

I meant 5R4. 5R4GA to be precise. So I'm wondering if the 5AR4 would work with my Heathkit W5m monoblocks and/or what would be a commonly available substitute.

Thanks

JohnR · « **Reply #3 on:** 14 Jun 2011, 11:16 pm »

Looking at the schematic of the W5m, the power transformer secondary has a fairly high voltage (455V). It seems to be within the rating of the 5AR4 but you will also end up with a higher B+ voltage. Add to which your supply voltage is probably higher than the nominal 117V the amp was designed for, and I would suggest some caution here.

rajacat · « **Reply #4 on:** 15 Jun 2011, 03:45 am »

Thanks,

I think I'll be safe and make do with the specified 5R4's that are only available old stock. No point in taking chances with my precious modded/rebuilt W5m's.
---------
Well I did find an alternative.
If I was willing to spend $$, these Jadis 274B Western Electric copies might be interesting.

chrisby · « **Reply #5 on:** 23 Jun 2011, 04:53 pm »

a bit late to the party, but don't you need to be careful with the value of first C in a Cap input filter with the 5R4? (as in 4mf vs 32 or higher)

JohnR · « **Reply #6 on:** 24 Jun 2011, 03:55 am »

Might depend on the specific type - my RC30 gives the 5R4GB a spec of 20 uF.

2wo · « **Reply #7 on:** 29 Jun 2011, 02:59 am »

The 5R4 is a very tough tube, you need to be careful that any proposed Sub is up to the task.

More info, Amp name, what and how many tube it needs to run, Careful with those nice 274B's