KlipschFan61
Smooth Jazzer
I have an amp of similar configuration and found the PSVane UK-6SN7 to be "the one". Didn't like any of the other, less expensive offerings.
Help me choose a couple of 6N8P/6SN7
- Thread starter releone71
- Start date
rudolfo
Super Member
Going back a bit on the 5Z3PA. Really looking for a backup or in case it fails. I don't really wanna go wit the mumbo-jumbo but seems like they don't have the original 5z3pa metal base anymore. I tried using a new 5u4gb and its giving me a fast start sound that's evident on my speakers when I turn it on.
So I set that aside. I have some new 5ar4 and 5v3a raytheon but I haven't tried it yet. If I can get the original metal base, I wont even bother going to a replacement route. My take is, are there any updates for the correct replacement of this tube. Its a rectifier for a SET 300b 8 watts. 4-prong (normal) not like the 300b socket.
FlaCharlie
Super Member
Mumbo-jumbo?? What exactly do you mean?
And I'm not sure how a faster startup rectifier like a 5U4 would affect your speakers. I've got amps that use slow start (indirectly heated) rectifiers like the 5AR4, fast(er) start (directly heated) rectifiers like the 5U4GB and amps that use solid state rectification, which start up essentially instantly. I've never noticed any affect on my speakers.
The 5AR4 will give you a slow start but it probably has less voltage drop than the original 5Z3PA if it really is equivalent to a 5U4. If so, the voltages will go up in the amp. The 5v3a is directly heated, like the 5U4, so it's not slow start.
Not sure what you mean by "updates" but rectifiers aren't made specifically for use with certain power tubes, like the 300B. They are designed to provide certain maximum voltages and current. The data sheets will tell you if a particular type can be used with a particular circuit.
All those rectifiers you show have octal bases. An octal base has spaces for 8 pins regardless of how many pins are actually present. It also has a center guide pin (plastic) so it can only be inserted one way. If only 4 pins are needed, they often omit the others to save money since they wouldn't be doing anything anyway.
What makes you think the 5Z3PA, or the equivalent variations, are no longer available? I just looked on eBay and there they are.
rudolfo
Super Member
Mumbo-jumbo?? What exactly do you mean?
And I'm not sure how a faster startup rectifier like a 5U4 would affect your speakers. I've got amps that use slow start (indirectly heated) rectifiers like the 5AR4, fast(er) start (directly heated) rectifiers like the 5U4GB and amps that use solid state rectification, which start up essentially instantly. I've never noticed any affect on my speakers.
The 5AR4 will give you a slow start but it probably has less voltage drop than the original 5Z3PA if it really is equivalent to a 5U4. If so, the voltages will go up in the amp. The 5v3a is directly heated, like the 5U4, so it's not slow start.
Not sure what you mean by "updates" but rectifiers aren't made specifically for use with certain power tubes, like the 300B. They are designed to provide certain maximum voltages and current. The data sheets will tell you if a particular type can be used with a particular circuit.
All those rectifiers you show have octal bases. An octal base has spaces for 8 pins regardless of how many pins are actually present. It also has a center guide pin (plastic) so it can only be inserted one way. If only 4 pins are needed, they often omit the others to save money since they wouldn't be doing anything anyway.
What makes you think the 5Z3PA, or the equivalent variations, are no longer available? I just looked on eBay and there they are.
Oh that's easy. I never even thought about going to ebay beside tube depot. I this case I will just by the identical one on ebay and thanks for letting me know.
What I mean by mumbo-jumbo is replacing it besides the original tubes then get a surprise after 6 months, Besides I'm thoroughly happy with the sound of this amp having it going 4 years now so Ill leave it original besides the output tube which I'm using is a mesh acme. Just incredible!
Thanks,
Edited: I checked a few minutes ago and I saw one or 2. Its not identical. I might need to look more further.
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FlaCharlie
Super Member
What the heck is a "mesh acme" output tube?? Gotta pic or a link?
As for the rectifiers, here are the data sheets for the 5Z3P and 5Z3PA. I don't read Chinese, but there seem to be only very minor differences, nothing that would affect the function of your amp.
http://tubedata.milbert.com/sheets/095/5/5Z3P.pdf
http://tubedata.milbert.com/sheets/095/5/5Z3Pa.pdf
For comparison, here's the data sheet for the 5U4GB:
http://tubedata.milbert.com/sheets/093/5/5U4GB.pdf
Again, my main concern would be the value of the first cap after the rectifier. These Chinese rectifiers specify a maximum of only 4uf while the 5U4GB allows up to 40uf. Although the cap size can be larger if the circuit isn't pushing the rectifier to its limits, it's not uncommon to see Chinese amps use caps that are way too large.
Do you have an accurate schematic or a detailed pic of the insides that shows the value of the first cap?
rudolfo
Super Member
Acme is the old light bulb non-st bottle. I'm not sure how the original western electric sounds like but this is the copy of it and I really like the sound of this tube. Its perfect if you have like a typical 6sn7 black plate Sylvania preamp tube which sound bright then with this output tube has more 3d sound, warm and a lot of bass. I cant ask for anything more.
In regards to the schematic which I don't have right now, I been trying to get it since February but I still don't have it yet. Thanks for that link and its really informative.
Do you think if I decided to just use a 5AR4/GZ34, change what is necessary like the caps, wirings so I can bring it up to really suitable and running smooth. Will it affect the sound?
Thanks,
joe
FlaCharlie
Super Member
I assumed that it was a mesh plate tube but I'd never heard of Acme - except in the old Road Runner cartoons.
Is that the brand? The difficulty in finding accurate, or often even inaccurate, schematics for Chinese amps is a common problem. What's the brand and model # of the amp?
I'm not a fan of circuit board construction and it's hard to see exactly how it's wired. But they have a resistor coming off the rectifier which should allow for the use of a somewhat larger first cap. Hopefully the first cap is one of the 33uf ones on the right and not that huge cap on the left.
If you want to try the 5AR4 it would be best to measure the voltages first, then with the 5AR4 installed, bring the amp up slowly with a variac and see how much higher they go. Then do the math to determine that the higher voltages aren't running the tubes, caps, etc too hard.
If you don't have capability to do that, I would stick with either the stock rectifier types (any of the Chinese 5Z3 versions) or a 5U4GB.
rudolfo
Super Member
I assumed that it was a mesh plate tube but I'd never heard of Acme - except in the old Road Runner cartoons.
The difficulty in finding accurate, or often even inaccurate, schematics for Chinese amps is a common problem. What's the brand and model # of the amp?
I'm not a fan of circuit board construction and it's hard to see exactly how it's wired. But they have a resistor coming off the rectifier which should allow for the use of a somewhat larger first cap. Hopefully the first cap is one of the 33uf ones on the right and not that huge cap on the left.
If you want to try the 5AR4 it would be best to measure the voltages first, then with the 5AR4 installed, bring the amp up slowly with a variac and see how much higher they go. Then do the math to determine that the higher voltages aren't running the tubes, caps, etc too hard.
If you don't have capability to do that, I would stick with either the stock rectifier types (any of the Chinese 5Z3 versions) or a 5U4GB.
Its a Boyuurange 300 mk III. I will try to look for the original rectifier tube besides the one on ebay (which is a copy of the original russian tube) and if I cant find it. Then I will try the 5ara like the same process that youre talking about. This amp is originally designed as all point to point. There are so many version and changes due to some R&D noise that they were working on. They improved the wiring on this version going to the rectifier although there is still an itty-bitty noise but I cant hear it anymore after 1-1/2 feet.
In fact I maybe the first one to buy this amp because I had the version 2 and it has a strong hum that's coming from the rectifier. that was all point to point.
I have an old Yaqin MC-100b tube amp that I bough back in 2010. It actually ended up on of my best sounding amp. But along the way there was so much ups and down times. I did so much modification and time involved just to make it run smoother and the way how I want it.
Lucky enough I got this amp and liked the way it sounds and which is much more simpler circuit. As much as possible, I don't want to make any more modifications (if I can) because I already have my previous fair share of the yaqin's spaghetti wires and cobb webs. I still have the amp today and I just have it now as a backup in my living room for a rock and roll sound.
Going back to the 300b amp.. Somewhere along the way... maybe I will upgrade the OT with a hashimoto or something in that category. But that's just a wish list.
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rudolfo
Super Member
Going back to the 5z3pa, I was able to acquire another original tube for a backup. And at the same time I also got a new old stock 5u4"g". I tried putting it on the amp and seems like this tube is one of the closest replacement I can get as far as in reading. The only thing about it is the heat transfer of this tube is a bit more than my stock 5z3pa. If I decide to use this tube, it will be my last backup.
I bought a pair of these GE 6SN7GTA Tubes Side Getter;Copper Posts;Short Bottle tube for my Nobsound 6P1 amp and love how they opened up the bass and toned downed the high end. I've tried several different 6SN7 tubes and these were very obviously better sounding. Attached is a picture, a matched set that measured NOS were less than $40.
As others have stated, do some research on rectifier tubes, both the filament ma and how much voltage they pass. The wrong one can either overload the transformer and/or raise the voltages in the amp.
https://www.kcanostubes.com/content/rectifier-comparison-and-interchangeability-chart
As others have stated, do some research on rectifier tubes, both the filament ma and how much voltage they pass. The wrong one can either overload the transformer and/or raise the voltages in the amp.
https://www.kcanostubes.com/content/rectifier-comparison-and-interchangeability-chart
