1959 Tweed Bassman Board Build

[sluckey]

Ha! Wrong color. Why not just bolt it down and hook it up?

[plexi50]

I tried so bad to find the light blue one but no luck. Most of them on Ebay are too big as well. The other orange ones are pretty small  (penny size).
I am am not sure what they are rated at either. I have like a 58VAC bias tap. Educate me on these rectifiers.

[plexi50]

Can i use this orange one from the box?

[plexi50]

Ha! Wrong color. Why not just bolt it down and hook it up?

It works!

[sluckey]

I was just kidding. I left the selenium rectifier in my 5F10 just because it was working, but if it ever fails I'll replace it with a trusty 1N4007.

I never bought into the amp forums' chatter about toxic poisons associated with selenium. I've worked with selenium rectifiers all my life, some as big as gallon paint cans. I respect the fact that they are poisonous but I don't intend to eat one or smoke one. I don't chew on lead or sip antifreeze either!   

Back in the late '60s we used to occasionally pull a trick on the instructor in tech school. At the end of the day the circuit breakers for lights and work benches would be turned off. Someone would connect a SR across a tv cheater cord and plug it into a workbench outlet. Whoever turned the breakers on the next day got a strong rotten egg smell as the selenium rectifier smoked! We didn't know it was poison gas back then. No one ever suffered except for the foul smell. Well, there was that one time with Billy, be that was probably the mushrooms!   

Anyhow, at least you know how to connect one properly. And if you ever smell rotten eggs, you'll know where to look. 

[plexi50]

That a real good story! Man i don't want to smell that smell. I used to drill water well's in the early 1980's. The sulfur smell of rotten eggs is pretty bad at times. Depended on how much vegetation and such from the Dinosaur era there was.
I drilled Lion Country Safari's well in Palm Beach at 800'. I had someone with a shotgun keeping an eye out for lions while drilling in the field. Looking back i don't think i would do that again.

[plexi50]

I couldn't resist buying these NOS 1958 CBS 5881 tubes. I feel like i am paying alimony to my 5F6A amp.

[HotBluePlates]

CBS made tubes, so I assume they made those. But aside from the label, those look 100% like 50's Tung Sol 5881's.

[plexi50]

Yes they sure do HBP. And maybe a tad more robust. But what turns me on is the script on the box:

A Division Of Columbia Broadcasting System Inc. Guaranteed 1000 year usage! Ha!

Edit: I ran across a tube store that has these same tubes and are advertised as being made by Tungsol.
 

[plexi50]

I am going to try a NOS RCA GZ34 i just bought and compare voltages with the NOS CBS 5U4GB i have in the amp now.
I looked at cheaper tubes but i just have this thing for vintage real tubes made of stronger metal than they use today.
Welded plates vs Stapled plates as well.
 

[Willabe]

Oh you have an RCA GZ34, nice!     

[plexi50]

Oh you have an RCA GZ34, nice!     

Not yet. Just paid for it. Looks nice

[eleventeen]

They want money for those.


I have been able to get NOS RCA 5V4A tubes for under $10 each. No, it ain't a GZ34.  It ain't $50 either for a dumb rectifier. But it's a robust tube w/indirect heating and the later ones, the ones that are NOT shaped like bowling pins but same envelope as RCA 6L6GC: straightsided but with that slightly rounded top. Those are nice tubes.

[DummyLoad]

Power transformer from a 1962 Wurlitzer Organ. 360-0-360. ... I was shooting for 325-0-325 for the original Tweed Bassman B+ of 400 VDC on the power tube plates. ...

I believe you'll have over 450vdc loaded, and a tad over 500vdc unloaded.

Yeah i know it's not the right PT for this.
I am just going to spring out in the morning,load my visa and buy the right PT for it. I have come this far and i don't want to skimp and wind up with a Tweed Ampeg. The PT has been removed/

it'll sound better with the higher b÷.

--pete

[plexi50]

The 5V4 is a fine tube. I used to have some of them. I am looking forward to hearing the amp with that GZ34.
I look at it and don't believe sometimes i actually built it with all the old parts i could find. And that they were all good parts.
I wanted to do it proud

[p2pAmps]

Amazing build, congrads

[plexi50]

Amazing build, congrads

Thanks much mscaggs. Cant wait to get the tweed head cab being made by John Mergili

[HotBluePlates]

I am going to try a NOS RCA GZ34 i just bought ...

RCA box & label, but that's a Mullard GZ34; again 100%.

The plate structure, "Made in Great Britain" label, hole in the guide post and 2-line code in faint gray on the glass (above the "RCA Electron Tube" on the base) confirm it's a Mullard GZ34. Hard to see, but the 1st character in the upper line of that code looks like a "B" which indicates Mulard's Blackburn plant.

[uki]

Bravo !! 

[plexi50]

I am going to try a NOS RCA GZ34 i just bought ...

RCA box & label, but that's a Mullard GZ34; again 100%.

The plate structure, "Made in Great Britain" label, hole in the guide post and 2-line code in faint gray on the glass (above the "RCA Electron Tube" on the base) confirm it's a Mullard GZ34. Hard to see, but the 1st character in the upper line of that code looks like a "B" which indicates Mulard's Blackburn plant.

I have had a lot on my plate lately (not tube related) and didn't even notice the hole in the guide pin and BK Mullard script before i purchsed it. I stole that tube for $125.00 + $5.95 ship. Thanks for noticing all that HBP.

[HotBluePlates]

... didn't even notice the ... BK Mullard script ...

The "BK" on the tube base is RCA's date code. Look on the glass above the "A" in "RCA" for a faint code, 2-lines made of ~3 characters per line. The 1st character in the top line is probably a "B".

[Ed_Chambley]

What is the big deal with the GZ34 Mullard?  The metal base ones bring insane money.  I have a a few around.  One has Heath on it another Amperex and a couple of RCA's as well.  I have heard they are very durable, but is there some other reason they are in great demand?

[plexi50]

What is the big deal with the GZ34 Mullard?  The metal base ones bring insane money.  I have a a few around.  One has Heath on it another Amperex and a couple of RCA's as well.  I have heard they are very durable, but is there some other reason they are in great demand?

I wonder why they are so expensive as well. No answers from me. I can now see the faint digits HBP

[Willabe]

What is the big deal with the GZ34 Mullard?  The metal base ones bring insane money. 

I wonder why they are so expensive as well. No answers from me. I can now see the faint digits HBP

1 reason is the Hi-Fi guy's love them.

[HotBluePlates]

What is the big deal with the GZ34 Mullard?  ...  I have a a few around.  One has Heath on it another Amperex and a couple of RCA's as well. ...

A number of sources talked them up as the ultimate GZ34 (Mullard, as well as Amperex/Philips in general).

I have a few as well, never used them in anything.  To me, a rectifier with a larger voltage drop makes more sense in a tube amp where you want rectifier-sag or rectifier-sound...

[plexi50]

I wonder what the date code will be. I will have it here Wednesday.

[HotBluePlates]

I am wonder what the date code will be. I will have it here Wednesday.

From a probably-reliable source, Feb 1967.  The Philips factory codes I pointed you towards on the glass carry their own date code, and could be used to corroborate the RCA-brand date code.

[plexi50]

I am wonder what the date code will be. I will have it here Wednesday.

From a probably-reliable source, Feb 1967.  The Philips factory codes I pointed you towards on the glass carry their own date code, and could be used to corroborate the RCA-brand date code.

Yes i found that source info as well earlier tonight and saw RCA's secret code. BK Philips to reflect Feb 1967.
I think i can see The letter F ? B 2 but it is clearly eye ball guessing from the faded angle of the picture.

[uki]

Wow this is an amazing work !

[plexi50]

Wow this is an amazing work !

Thankyou uki. 

[plexi50]

Received 5AR4 / GZ34 this morning. Pin#4 dead. No filament or emissions. Bummed out. D*m!

[HotBluePlates]

Refund for DOA? (I hope)

[DummyLoad]

Received 5AR4 / GZ34 this morning. Pin#4 dead. No filament or emissions. Bummed out. D*m!

if you want it, i have a used GE 5AR4 with plenty of life left. 35bux + postage. last used one i have. 


--pete

[plexi50]

Refund for DOA? (I hope)

The seller says they have more NOS 5AR4 tubes and will do an exchange. I sent the bad one back yesterday.

Thanks DummyLoad i may take you up on that offer.

[plexi50]

Got a refund on the DOA RCA GZ34. Decided to grab this Amperex Bugle BOY GZ34 while i could.
Steve i found the powder blue Selenium rectifier. 1961 Date. 

[sluckey]

Steve i found the powder blue Selenium rectifier. 1961 Date.

Great! I heard that most of the Bassman magic is inside that rectifier. Don't let the stink out!

[plexi50]

Steve i found the powder blue Selenium rectifier. 1961 Date.

Great! I heard that most of the Bassman magic is inside that rectifier. Don't let the stink out!

Ha!!! What if i put a moth ball next to it? 

[sluckey]

Ha!!! What if i were to put a moth ball next to it?

Moth balls are easier to chew than selenium rectifiers. I loved that smell when I was a kid! 

[plexi50]

Ha!!! What if i were to put a moth ball next to it?

Moth balls are easier to chew than selenium rectifiers. I loved that smell when I was a kid! 

Moth balls did have a strange smell . If you sniffed to hard it would make your eyes water. Never sorted a moth ball.
Maybe that's the next craze we will here about in the news. 

[plexi50]

I received the Amperex GZ34 this morning. The code from what i can see is,

1 07

f33
LOD

My B+ is now 425VDC  (edit: (430 VDC) and bias grid is -48.5VDC. The amp does sound good with the plate voltage up from 408 VDC.

[Willabe]

 

[HotBluePlates]

I received the Amperex GZ34 this morning. The code from what i can see is
...
f33
LOD

That "L" is almost certainly a right-triangle. The right-triangle indicates Amperex's Heerlen, Holland factory.

[plexi50]

I received the Amperex GZ34 this morning. The code from what i can see is
...
f33
LOD

That "L" is almost certainly a right-triangle. The right-triangle indicates Amperex's Heerlen, Holland factory.

I am using magnifier lens and still cant see it all that good. This is the best pic i can get of it. Very difficult.

[plexi50]

Received the Tweed Head cabinet this afternoon. Just beautiful Craftsman ship. I had no trouble getting the holes marked and drilled for the screws. Of all things, i forgot i don't have any power cord retainers.

The Peavey 410 cab doesn't look so nice in comparison.

John Mergili sure does nice cabinet work.

[plexi50]

Wood knots!

[plexi50]

Dam this amp sounds incredible! Not to brag but man this thing is different than just another amp build for me. I have had several people play it and it is exceptional. I suppose that 4 ohm OT has it under control.
2 Ohm is loud but tone suffers. 4 Ohm has less bass and mid's but tone is greatly improved from what i have read online with a 4 ohm OT.
Of course this was a Hi-Fi thread i got this info from. Got the 5F6A Bassman tube chart and early 60's power cord retainer for it.
I'm in awe of having actually built it with all the NOS parts i have been able to find.
I will do a sound clip of it soon. More than a keeper.

[DummyLoad]

excellent workmanship.   


--pete

[plexi50]

I found a 1959 8087 power tranformer in a 1960 6G6 Blonde Bassman i worked on 2 week ago. I was drooling. Real early 6G6.
Never expected to see one in anything other than a Tweed Bassman. Pic of it/

Look at the circle on the transformer with the (T) inside of the triangle. It measured 380-0-380 VAC/