Vox AC30 CC2 5y3

[lowell]

So waiting on schem from Vox since can't find on online. I also cannot find ANY data on the JJ 5y3 tube. My concern in these Vox amps is that they put too much filtering on the output of the rectifier... 44uf. Wondering if JJ 5y3 can handle it or not. So I'm considering disabling the "modern" switch on the amp to save the customer another shorted 5y3.

[52 Bill]

So I'm considering disabling the "modern" switch on the amp to save the customer another shorted 5y3.

I thought that those came with a 5AR4/GZ34 rectifier tube.

[wyatt]

I thought that those came with a 5AR4/GZ34 rectifier tube.

+1/ They do.

Foolhardy to run a 5Y3, it can't supply enough HT current for a AC30, the expected load is 160mA, a 5Y3 can't supply that...combine that with high filtering, it's no wonder the 5Y3's are frying.

If he wants voltage drop/more sag, he should be running a 5R4; but I wouldn't put anything other than a 5AR4 in there.

[Jazz P Bass]

Plus that to the GZ34.
Here is the schematic.
Also the amp utilizes a 15 H inductor before the capacitor.
That changes things a bit.
With the coil in circuit, you can go higher on the cap value.

[pdf64]

5R4 are tall tubes, they don't fit in 60s AC30 cabs, so best to confirm whether the CC has enough room.
Pete

[lowell]

My bad I think they DO come with 5AR4. However I had previously put a 5y3 in here as to try and get the CC2 to not sound like crap... more authentic, old school, squishy, saggy etc...

Still why isn't JJ supplying data like they do will all their other tubes? I replaced this one with a 5y3 again but as a precautionary measure suggested the customer only run it in "vintage" mode (22uf filtering).

[Rick Erickson]

AC30's were`never squishy or saggy, unless they were not working correctly. The main reason the CC's blow their rectifiers is because of the Standby switch location. You can't dump unfiltered b+ directly into uncharged filter caps without stressing the rectifier. The original AC30's did not have a standby switch. They also don't blow out rectifier tubes very often. The choke is not before the first filter cap(s) so it is not helping the rectifier at all here. I tell my customers to either not use the Standby or pay me to rewire it so it works correctly.
For the record - I think the CC amps sound great. I think their construction leaves a lot to be desired though.

[potatofarmer]

Even with a lowered reservoir capacitance, the amp is going to draw more current than the 5Y3GT can reliably supply and you're going to keep popping them.

Check out this thread: http://music-electronics-forum.com/t32886/
...even if the AC30 would only draw 160 mA, that's already significantly over a 5Y3's limit of 125 mA.

If you'd like more information about JJ 5Y3s, ask any 5E3 builder how they feel about them. JJ makes these indirectly heated (so, not matching the specs) so the voltage drop across the 5Y3 is less, raising plate voltages and any tweed clone builder's day.

[lowell]

Have you heard Willie Nelsons cover of Daniel Lanois' The Maker. I thought it sounded an awful lot like an AC30 and a les Paul. Maybe its not... But certainly has some sag Or maybe call it bloom..happening. Song starts after initial faster tune ends. Guitar intro tone is killer.
https://www.youtube.com/watch?v=wGGU...e_gdata_player

[Mick Bailey]

Had plenty of these with blown GZ34s. I hard wire the standby so it's always on. Never had one back. I read somewhere there was a Korg bulletin on the subject.