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5U4GB Rectifiers


jcmusic
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The 5U4 has got to be the most popular rectifier tube out there. They are used in many audio and guitar amps and best of all, they are readily available and quite inexpensive. RCA, Sylvania, National Union, Raytheon, GE, KenRad - everybody made them by the boatload and to me, there's little discernible difference sound-wise between them. I guess my preference would be for the older 5U4G ST-type tubes from RCA and Sylvania. Of the common rectifiers, I prefer the 5AR4 for its slow-start capabilities (it ramps up the juice from the PS over a few seconds as opposed to instantaneously with tubes like the 5U4), then the 5R4. If you ever want to try out a few 5U4's, head to the next hamfest in your area where you'll find most US brands for @$5-10 each NOS or about $1 used (at least, that's the going rate 'round here). Have fun.

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Jay, I have used a 5U4 GA in my Latino ST120, I called Bob before I tried it and he said that it would not hurt it, and it could actually make my power tubes last longer because it didn't push them as hard. All this, if you didn't need all the power of the amp, With my Cornwall's, my pre volume knob is rarely turned beyond about 9 O'Clock position. I ran it like this for about 2 weeks and went to the Weber Copper cap SS rectifier. I like the SS rectifier, Zero problems with it.

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The 5U4 has got to be the most popular rectifier tube out there. They are used in many audio and guitar amps and best of all, they are readily available and quite inexpensive. RCA, Sylvania, National Union, Raytheon, GE, KenRad - everybody made them by the boatload and to me, there's little discernible difference sound-wise between them. I guess my preference would be for the older 5U4G ST-type tubes from RCA and Sylvania. Of the common rectifiers, I prefer the 5AR4 for its slow-start capabilities (it ramps up the juice from the PS over a few seconds as opposed to instantaneously with tubes like the 5U4), then the 5R4. If you ever want to try out a few 5U4's, head to the next hamfest in your area where you'll find most US brands for @$5-10 each NOS or about $1 used (at least, that's the going rate 'round here). Have fun.

JBryan,

I know all about the 5U4 tube and it's applications, what I wanted know was which ones you are usingand why. Which brand name? Does it have top, bottom, ot side getters? Are the the halo or D type? As for hearing differences I hear a pretty good difference in most, the Tung Sol's sound aggressive to me and the RCA's are laid back. Alot of the difference in sound has to do with the voltage drop and the age of the tube.

Jay

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Jay, I have used a 5U4 GA in my Latino ST120, I called Bob before I tried it and he said that it would not hurt it, and it could actually make my power tubes last longer because it didn't push them as hard. All this, if you didn't need all the power of the amp, With my Cornwall's, my pre volume knob is rarely turned beyond about 9 O'Clock position. I ran it like this for about 2 weeks and went to the Weber Copper cap SS rectifier. I like the SS rectifier, Zero problems with it.

Jeff,

About the GA this is true some of these rectifiers were made just a little different voltage wise, or how much voltage they can handle all of them are five volt rectifiers. There are positive's and negitive's to using different tubes, using a tube with a slow start may create some sag in the amp at the same time be easier on the power tubes. Using a tube that starts right away is going to be a little harder on the power tubes and sound more transparent in my opinion because it pushes the power tubes closer to their max capabilites. Now why did you decide to use a SS rectifier? How does it soun What have you noticed about it that is different than a tube rectifier?

Jay

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Jay the amp came with a 5AR4 Chinese rectifier. One day the main fuse popped. I replaced it and in a while it popped again. I called Craig at NOS Valves and we talked about it. He said that this being a ST120 it was pushing the 5AR4 to its limits and we also talked about the Weber copper cap. I also talked to Bob Latino and he said he really liked this amp with the SS recitier. I had two new ruby 5AR4's and ran one of them for about a month or two and then it went out. I had a 5U4GA that was an old tube and I called Bob and asked him if I could use it. He explained the difference to me and I put it in and re-biased everything. Had to crank up the bias on each of the KT88 power tubes.

The sound difference was not all that noticeable if any, probably more in my head, but sounded a tad bit warmer with the 5U4GA. I ran it like this till the Webber came in and then installed the Webber, re-biased and have had the copper cap in since then. No real notice in sound difference except maybe a little more push in the bass notes.

I think the design of this amp pushes a single tube rectifier to its limits. This amp could use two of the 5AR4's in my opinion, one for each side. I think I'll stick with the Webber for now. Some have advised me to find a NOS Mullard rectifier, but they are way too over priced to me & the SS Coper Cap is doing a fine job as it is.

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Jay,

I will assume you are asking about rectifiers in regard to your Korneff amp (cool amp BTW, its one of the few amps that I wish I had held onto). Given its low gain, I would suggest trying a Sylvania 5U4G as its a bit smoother-edged than other US brands. I had an early version of Jeff's 45SE amp with the silver hammertone chassis and red bell covers but I don't remember which rectifier it used. I did quite a bit of tube rolling in it and found that the 6SN7's had the most impact on the sound but I didn't find much difference by changing the rectifier. I know he offered several rectifier choices over the years and with slight modifications, you can try a myriad of tubes - 5AR4/GZ-34, 83 mercury vapor, 5R4, etc. If I still had the amp and a bit of inspiration, I would give the GZ-34 a try.

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Jay the amp came with a 5AR4 Chinese rectifier. One day the main fuse popped. I replaced it and in a while it popped again. I called Craig at NOS Valves and we talked about it. He said that this being a ST120 it was pushing the 5AR4 to its limits and we also talked about the Weber copper cap. I also talked to Bob Latino and he said he really liked this amp with the SS recitier. I had two new ruby 5AR4's and ran one of them for about a month or two and then it went out. I had a 5U4GA that was an old tube and I called Bob and asked him if I could use it. He explained the difference to me and I put it in and re-biased everything. Had to crank up the bias on each of the KT88 power tubes.

The sound difference was not all that noticeable if any, probably more in my head, but sounded a tad bit warmer with the 5U4GA. I ran it like this till the Webber came in and then installed the Webber, re-biased and have had the copper cap in since then. No real notice in sound difference except maybe a little more push in the bass notes.

I think the design of this amp pushes a single tube rectifier to its limits. This amp could use two of the 5AR4's in my opinion, one for each side. I think I'll stick with the Webber for now. Some have advised me to find a NOS Mullard rectifier, but they are way too over priced to me & the SS Coper Cap is doing a fine job as it is.

Ok Jeff,

Thanks for the info my friend!!!

Jay

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Jay,

I will assume you are asking about rectifiers in regard to your Korneff amp (cool amp BTW, its one of the few amps that I wish I had held onto). Given its low gain, I would suggest trying a Sylvania 5U4G as its a bit smoother-edged than other US brands. I had an early version of Jeff's 45SE amp with the silver hammertone chassis and red bell covers but I don't remember which rectifier it used. I did quite a bit of tube rolling in it and found that the 6SN7's had the most impact on the sound but I didn't find much difference by changing the rectifier. I know he offered several rectifier choices over the years and with slight modifications, you can try a myriad of tubes - 5AR4/GZ-34, 83 mercury vapor, 5R4, etc. If I still had the amp and a bit of inspiration, I would give the GZ-34 a try.

JBryan,

Maybe I should have been a little more detailed about my inquiry, no this is not about the Korneff 45 it is set in stone. This inquiry is about the new Super Baldwin amp I just got, it uses two 5U4's in PP configuration. So I just was hoping to hear from other members who are using this tube or have used this tube in their amps.

Jay

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Just to chime in on the Weber copper cap rectifiers. I use one in my Latino ST120, and it is quieter than the tube rectifiers I have used, and the bias doesn't have to be adjusted nearly as much on the power tubes. Of course if you have an amp with auto bias, that won't matter to you. The overall sound is virtually the same to my 55 year old ears, minus the added tube noise of the tube rectifiers. Let me point out that I have only used Chinese and Russian tubes, never any vintage tubes, so results may vary with pricier Vintage tubes.

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5U4GB's have slightly different specs than 5U4G's (marginally higher B+ I think, but don't quote me), so double check that they will work with your gear.

The 5U4GB's were made for televisions, and are probably the most ubiquitous of the NOS tubes as a result, so they're inexpensive. I've been using NOS RCA 5U4GB's in a couple of my Decware amps for some time and have absolutely no complaints.

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Canyonman said: "JBryan,

Maybe I should have been a little more detailed about my inquiry, no this is not about the Korneff 45 it is set in stone. This inquiry is about the new Super Baldwin amp I just got, it uses two 5U4's in PP configuration. So I just was hoping to hear from other members who are using this tube or have used this tube in their amps."

Sorry about that C-Man. I did make that assumption and that's why I was uncertain of what you were trying to accomplish by changing out the Korneff's rectifier.

Coincidently, I too, have one of Mr. Vincent's Baldwin amps driving a pair of Tannoy Windsors at the moment. The rectifier tubes that came with the amp are Sylvania 5U4GB's and I'm satisfied with them in that I never considered changing them out. I will be interested in any recommendations you get but for now, I'll just walk away quietly.

BTW, the power tubes on the Baldwin amp run pretty hot so this is one amp where 'proper ventilation' is more than just a recommendation.

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Do you hav a model number for the amp so I can pull the schematic. I was looking into 5U4X power supplies. Seen a few schematic's with parallel 5U4X running off a separate winding which was inverted (supposedly reduces noise thru cancellation). I briefly saw a schematic for dual split rail power where one side was - and the other +, but when I went back to get a second look could not find it. I would like to review how/what is being done in your amp.

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Canyonman said: "JBryan, Maybe I should have been a little more detailed about my inquiry, no this is not about the Korneff 45 it is set in stone. This inquiry is about the new Super Baldwin amp I just got, it uses two 5U4's in PP configuration. So I just was hoping to hear from other members who are using this tube or have used this tube in their amps."

Sorry about that C-Man. I did make that assumption and that's why I was uncertain of what you were trying to accomplish by changing out the Korneff's rectifier.

Coincidently, I too, have one of Mr. Vincent's Baldwin amps driving a pair of Tannoy Windsors at the moment. The rectifier tubes that came with the amp are Sylvania 5U4GB's and I'm satisfied with them in that I never considered changing them out. I will be interested in any recommendations you get but for now, I'll just walk away quietly.

BTW, the power tubes on the Baldwin amp run pretty hot so this is one amp where 'proper ventilation' is more than just a recommendation.

JBryan,

Well how do you like your Baldwin? My came with a pair og GE 5U4GB's they were a little noisy, I put in a pair of RCA's much better. Now Mr. Vincent suggest trying a 5V4 in it, he said it be easier on the tranny like that's gonna be a problem!!! LOL!!! Also it operates at 2.0 instead of 3.0 where the 5U4 is. Anyway my problem is the voltage drop with the 5V4, it is something like 17 volts vs 50 volts of the 5U4GB. With so little a drop my fear is it will make the amp too aggressive, and right now it is on the borderline of where I like it. So hence the inquiry about GB's. I happen to know that RCA's are a little more laid back then say a Tung Sol, that is what I use in the Korneff 45.

Jay

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Do you hav a model number for the amp so I can pull the schematic. I was looking into 5U4X power supplies. Seen a few schematic's with parallel 5U4X running off a separate winding which was inverted (supposedly reduces noise thru cancellation). I briefly saw a schematic for dual split rail power where one side was - and the other +, but when I went back to get a second look could not find it. I would like to review how/what is being done in your amp.

Rick,

I am not sure what the model number is but, I am trying to find out. Ok I found out it is called a Model AD.

Jay

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Canyonman said: "JBryan,

Well how do you like your Baldwin? My came with a pair og GE 5U4GB's they were a little noisy, I put in a pair of RCA's much better. Now Mr. Vincent suggest trying a 5V4 in it, he said it be easier on the tranny like that's gonna be a problem!!! LOL!!! Also it operates at 2.0 instead of 3.0 where the 5U4 is. Anyway my problem is the voltage drop with the 5V4, it is something like 17 volts vs 50 volts of the 5U4GB. With so little a drop my fear is it will make the amp too aggressive, and right now it is on the borderline of where I like it. So hence the inquiry about GB's. I happen to know that RCA's are a little more laid back then say a Tung Sol, that is what I use in the Korneff 45.

I've had the amp for a few years but honestly, its spent more time on loan to audio buds than in my house so I really don't have much time with it. My impressions so far are pretty good - the amp is quiet and well-defined. The Tannoys are forcing my hand to more power. They replaced a pair of Zu Definitions that were being driven by a Yamamoto A-08S 45SET amp (2w) and although the Tannoy's high end sounded very nice, the bottom was anemic (not a surprise). I then tried a Brenneman Cavalier EL34SE (10w) but felt the woofers were still underpowered. I was hoping to try out a Scott 222c (22w) next but the amps' 5AR4 rectifier blew and I'll need to have the amp checked before hooking it up so I asked to borrow the Baldwin back and it seems to be working well.

I haven't considered changing any tubes yet but I may play with the driver tubes (12AX7) as the output level is a bit low - pretty much the same volume as the 45 amp but with better bass control and headroom. I'm also considering using another preamp as the Joule Electra I'm using now has pretty low gain which, in concert with the Baldwin's lower gain may not be a good combination. Once I get the right component mix, I'll be able to give the Baldwin a fair listen and go from there. So far, so good though...

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Jay

I'm glad you are putting those Winged C 6L6s to some good use, and that the amp has been satisfactory.

I have a couple of EH 5U4G rectifiers here that I'm not using. I'll send them to you if you'd like to try them. Of the few I've tried with the 300B monoblocks I built last year, the Svetlana 5U4s have been really nice, quiet, too.

One thing to think about if you start experimenting with different rectifier types is the input to filter capacitor value, though particularly in the case of a cap input (which is the first capacitor after the rectifier. If the amp uses a choke input (I honestly can't remember which the Baldwin is) after the rectifier, it's different. Some rectifiers are able to handle much higher input cap values than others, as is the case with the 5AR4. As an example of the opposite, the Mullard GZ37, which I use in my Moondog 2A3s, has a very low recommended value for the input cap -- 4uf, I think, off the top of my head. You can have problems if you use a rectifier designed for very low input capacitance as a substitute where values more in the range of up to say 60uf would be okay.

Another thing to think about is the different current draw between these different 5 volt rectifiers. One CAN'T simply plug one in for the other as an acceptable replacement without considering the above.

Have fun,

Erik

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Hi, Jay

Great -- this is one of the reasons why I thought you might like this amp over the other one discussed. You get some advantages of indirect heating/slow warm up, which is nice for tubes and makes them live happily. Other than that, what you get is either more or less voltage sag, which might be reflected in certain performance aspects. The only differences I seem to be able to hear with these things has to do with some of the valves being quieter than others, but I just like the idea of slow warm up if possible.

Enjoy,

Erik

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