5AR4 /GZ34 made in japan -

[angelodp]

Anyone familiar with this tube, it works and sounds good in my Rocket. Thought I would try a different flavor after hearing rawnsters clips with a mullard GZ35 in his rig. This tube has a seam on top and says lifetime on it. Also says made in japan. Wondering if others may be familiar with this tube. I like the difference with this tube, more top end and clarity, later breakup and sightly tighter feel.

ange

thanks tom

[Structo]

[IMG2456]http://i260.photobucket.com/albums/ii9/ ... G_2352.jpg[/img]

[IMG1704]http://i260.photobucket.com/albums/ii9/ ... G_2353.jpg[/img]

[mojo2001]

Well, it is a Radio Shack "Realistic Lifetime" branded tube. Probably an NEC manufacture bottle.

[angelodp]

Radio shack, that sounds iffy.... is a sign that the tube is poor quality??

ange

[Phil_S]

No, many of them are sleepers.

[billyz]

I have found the Japanese tubes to be of pretty good quality, they sound good and are fairly durable too. I prefer them over most of the newer made crap. I just put a pair of Toshiba 6v6's in a Amp and while not as good as the RCA they were very nice sounding and the pair matched up very closely. I liked them better than some other vintage 6v6's I have used, like brimars, CBS and more.

[angelodp]

Ok, this is good news,

So do I understand correctly that the 5AR4 will put less stress on the circuit than the 5U4.

ange

[M Fowler]

The 5AR4 has less voltage drop than the 5U4.

But remember the the 5AR4 is 2amp and 5U4 is 3amp so the 5AR4 can replace a 5U4 but not the other way around.

Unless the PT is rated for 3amps. If it can, then you will see a lower voltage with 5U4.

Mark

[tweedeluxe]

I assume that since the GZ34 is indirectly heated and warms up slowly, it can more easily cope with 80uF as the first filter. Correct me if I'm wrong, but the first filter cap is like a short to ground until it it charges up.

If the GZ34 slowly ramps up to the maximum supply voltage, then the inrush of current as the cap charges shouldn't be as severe.

I think this is why Ken didn't use the 2 100k R's to ground before the standby switch on the Rocket. He wanted to keep the 80uF filter on the first node charged. From this I would also infer that it is best to put the Rocket into standby before turning it off (for rectifier longevity).

[M Fowler]

I have heard some guys say since I have a GZ34 slow turn on rectifier tube I don't need a standby switch.

I incorporate a standby switch in the build regardless. But I have to admit that I forget to go through the sequence of using the standby at shut down.

tweedeluxe,
Based on your note I am going to make it a practice like you said "to put the Rocket into standby before turning it off".

Mark

[gahult]

Mark,

With all flavors of the Trainwreck your entire cap stack will not discharge threw the bleeder resistors unless you leave the standby in the on (closed) position.

The switch isolates all but the first two caps if it is flipped when powering off.

The first two caps are the only ones that will bleed with the switch open.

How long does it take for the cap stack to bleed? I am not sure. I have never hooked a meter in to monitor the discharge after power off.

Even with the standby switch closed I go in and manually discharge the stack before I poke around so it doesn't poke back.

Gary

[M Fowler]

Gary,

Thanks, I bleed my caps off manually when working on them too, but for gigging I put the amp on standby go harass the crowd and then flip the switch to make some sweet music. At the end of the night I just start flipping off the PA power amps and board and my amps in such a hurry to pack up and get home by 2:30-3am that I don't even think about what I am doing with the standby switch.

Mark

[gahult]

Mark,

I know how that goes at the end of the night. Especially if it is bar/beer related as in my younger days. Hell, sometimes I even forgot to go home.

I usually try to leave the standby on with the amp sitting around the house till I go to use it. But then again I have to remember to put it in standby before I power up.

And so it goes. My memory that is. It's hell to get old.

Gary

[Structo]

I assume that since the GZ34 is indirectly heated and warms up slowly, it can more easily cope with 80uF as the first filter. Correct me if I'm wrong, but the first filter cap is like a short to ground until it it charges up.

If the GZ34 slowly ramps up to the maximum supply voltage, then the inrush of current as the cap charges shouldn't be as severe.

That is my understanding as well.

In my little 6V6 amp, I am using a 5U4 since that is what Hammond used in this amp before I converted it.

I like the fact it drops 45v too.

But I do give it plenty of warm up time before I flip the standby.
This is a directly heated cathode so it's good to let it heat.

I have the standby switch before the first filter cap, that's just the way I've always done it.

When I work on it, I just use a test lead and clip one clip to a plate resistor on a preamp tube and the other one to chassis ground.
Within a minute or two, the caps are bled down to a safe level.

I was wondering if it would hurt anything to use a 220K bleeder across the first cap to ground?

I've seen the pair of 220K balancing resistors used when there is two large caps on the first filter and they bleed the voltage down quickly.

So if I used a single 220K from the cap to ground what would it do?