View Full Version : Dumb tube substitution question


tentoze
08-31-2005, 10:37 PM
Being still pretty stupid about tubes and all the alphanumeric confusion, a question for the experts:

My late model chinese pre-amp uses a 5Z4-G rectifier tube. Anyone tell me if a 5U4G is a compatible substitute?

Thanx,

et

Celt
08-31-2005, 10:47 PM
Yes, that will work Toze. As well as a 5AR4 or a 5Y3GT. :yes:

tentoze
08-31-2005, 10:48 PM
Yes, that will work Toze. As well as a 5AR4 or a 5Y3GT. :yes:

Thank you, sir- it's a cooler looking tube (and BIGGER).........


:D

Celt
08-31-2005, 11:16 PM
Now bear in mind it isn't as *strong* a rectifier as the smaller 5AR4...but yes, they can look cool if dressed out in a coke bottle shape. I have a few pre WWII NOS 5U4's.

tentoze
08-31-2005, 11:31 PM
Now bear in mind it isn't as *strong* a rectifier as the smaller 5AR4...but yes, they can look cool if dressed out in a coke bottle shape. I have a few pre WWII NOS 5U4's.

I like the looks of this one.........(bad pic, I know)

Mike Stehr
08-31-2005, 11:54 PM
Hey it's a BEZ pre.......good little pre-amp for the cash from what I understand.

tentoze
09-01-2005, 12:31 AM
Hey it's a BEZ pre.......good little pre-amp for the cash from what I understand.

No complaints here- I love it. Still sounds fine tonight after rolling a few tubes.

Kegger
09-01-2005, 03:05 AM
I have one of the little dared sl-2000a tube preamps that uses the 5z4p and I
substituted the 5y3gB coke bottle mazda tube, it looks much better and even
changed the sound a little, giving an overall smoother tone.

I believe the the 5z4p also was an indirectly heated=slow-warmup tube where
the 5y3gt is not, but the 5y3gb Mazda is. Just some info for thought!

Chad Hauris
09-01-2005, 07:21 AM
5Y3 GT is not a slow warmup tube, it is a filament type (as is the 5U4), as soon as you see the glow it's working (about 2 seconds).

The 5Z4 is a slow warmup, indirectly heated cathode tube.

The 5U4 has a 3 amp filament and the 5Z4 is 2 amp so you need to watch that you don't overheat your power transformer due to the increased filament draw. Also the 5U4 has a larger voltage drop so the DC voltage output may be lower than when using the 5Z4.

Kegger
09-01-2005, 02:01 PM
Sorry typo: I meant THE MAZDA 5Y3GB is indirectly heated=slow-warmup tube!
That is the one I used in my pre.

I can't remember now if the 5z4p was indirectly heated or not now (it's been a while)

Billfort
09-01-2005, 02:13 PM
Maybe just me being paranoid about tube life (comes from using rare-ass tubes like Western Electrics and globe 245's) but I would definitely prefer a slow warm-up indirectly heated rectifier like a 5Z4 over a fast-on 5U4 - no matter how sexy it looks.

It may be overkill but it's nice to have those heaters warming for a little while before whacking a tube with the HV. In my next 300B amp I'm wiring all the filament transformers separately so I can turn them on first but an indirectly heated rectifier pretty much does the same by default.

Kegger
09-01-2005, 02:19 PM
Billfort I completly agree with yu and that is why I searched and mentioned the
MAZDA 5Y3GB as a good solid replacement that is indirectly heated plus looks cool!

I to am a little worried about my expensive tubes so when I did some searching this
tube came up as being an excelent replacement.

------------------------
5Y3GB rectifier NOS vacuum tube, 1950's production by French Mazda.
"ST" shaped, Great tube for that "retro" look

yrly
09-01-2005, 04:04 PM
The later Mazda 5Y3GBs looks really cool, like a big power amp tube, I got two of them in an auction out of Toronto about a year ago. You can make it out vaguely in this picture over in the gallery of my preamp...http://www.audiokarma.org/gallery/showphoto.php?photo=1266&password=&sort=1&cat=500

Kegger
09-01-2005, 06:33 PM
Yrly that does look different, I thought all the mazda 5y3gb's look like the one above!
(in my edited post)
Your right that does look like a power tube, like an el34 fat body or 6550 kinda!

yrly
09-02-2005, 01:05 AM
Date coding on those odd 5Y3GBs are both out of the 60s, can't remember exactly but it was mid to late 60s. Still indirectly heated but the plates are differently shaped than the earlier ones. I don't know how the early ones glow but those late ones glow bright. How bright? You can see it's glow on the ceiling about 2 1/2 feet above the preamp when the lights are off. Darn bright, looks more like a power amp tube when lit up. I don't use them anymore though I did like the sound, here is the reasoning... I paid almost $20 after shipping from Canada for the two of them (a bit expensive for 5Y3s), and I bought them partly for the unique shape. I stopped using them because aside from the two I have, I have never seen another of the shape (though early ones seem easy enough to find), and the 12AX7s are not particularly fancy, just a set of Sylvanias, so I wanted to save the slow warmup ones for the day I put the Mullards in there. I used the one for a few months, pulled it and tested it (still over 100% on the tester), tested the other (also perfect), boxed them back up, put a little piece of paper in the used one letting me know I had used it, and that was that. I have a Sylvania 5Y3G in there now circa late 1930s (I bought two boxes of NOS tubes at the flea market about a year ago for around $50, kept the ones I needed and sold a good portion of the rest, and some of it was good stuff, there were 6 NOS ST shape Sylvania 6L6s in there), so I will probably leave that in until I go to the Mullards. These are the best 5Y3s sound quality I have used in the preamp, right up there with that oddball Philco. You would not think it would make that much difference, but its pretty dramatic, double blind you'd be hard pressed not to notice the difference. Still its a pretty cool tube and I wish I could find more.

jpchleapas
09-02-2005, 12:53 PM
Being still pretty stupid about tubes and all the alphanumeric confusion, a question for the experts:

My late model chinese pre-amp uses a 5Z4-G rectifier tube. Anyone tell me if a 5U4G is a compatible substitute?

Thanx,

et

Try this site for tube substitution options. There are lots of tube sub books out there, Good luck! John

http://www.nostalgiaair.org/Tubes/

tentoze
09-03-2005, 04:50 PM
Try this site for tube substitution options. There are lots of tube sub books out there, Good luck! John

http://www.nostalgiaair.org/Tubes/

Yeh, I have that site bookmarked, but I'm not sure it's all-inclusive.

How about 6SN7GT for 6SN7?

Celt
09-03-2005, 05:06 PM
How about 6SN7GT for 6SN7?
Yep...that'll work too...as well as a 5692's, 6SN7WGT (my fave), ECC33's and 5692's. :yes:

Billfort
09-03-2005, 05:54 PM
or my favorite for the 6SN7, CV1988