2359glenn | studio

[gibosi]

  I'd suggest adding a garden variety 5U4G and 5U4GB (any USA brand) to serve as a comparative basis against the other tubes since it is used so commonly by so many people.

 
I have two RCA 5U4G, one from the 1940s and one from the 1950s, but since this rectifier has a maximum DC output current of 225ma, Glenn has discouraged me from using it with 6AS7 output tubes. However, the upgraded 5U4GB is able to provide about 275ma and they are cheap. So for the good of the order, I will pick one up and add it to the list.

 

[2359glenn]

 

  I'd suggest adding a garden variety 5U4G and 5U4GB (any USA brand) to serve as a comparative basis against the other tubes since it is used so commonly by so many people.

 
I have two RCA 5U4G, one from the 1940s and one from the 1950s, but since this rectifier has a maximum DC output current of 225ma, Glenn has discouraged me from using it with 6AS7 output tubes. However, the upgraded 5U4GB is able to provide about 275ma and they are cheap. So for the good of the order, I will pick one up and add it to the list.

The 5U4GB is a good tube better then the 5U4G but most people don't like it.
I think it is not due to the sound but the 5U4G looks cool.

 

[gibosi]

The white Suzier-made B4 to 5U4G adapter arrived today. First impressions, the build quality is much better. I do not expect to ever have the need to repair them.
 

 

 
However, fit continues to be a problem. Evidently, the thickness of the pins on B4 bases varies considerably from manufacturer to manufacturer. And as with the yellow-top adapter, some tubes, such as the Tungsram PV 200/600, cannot be inserted completely without more force than I am comfortable using. And then, of course, considerable force would also necessary to remove the tube and the tube could easily be damaged...
 
Perhaps with time the socket will loosen up somewhat. On the other hand, even though it is ugly, inserting the tube until good and snug, typically about half-way for some, such as this Tungsram, works fine.
 
So my conclusion is the Suzier adapters are better, but not perfect. That said, given the variability in B4 bases, building a "perfect" adapter may not be possible.
 
 

 

[Xcalibur255]

   
I have two RCA 5U4G, one from the 1940s and one from the 1950s, but since this rectifier has a maximum DC output current of 225ma, Glenn has discouraged me from using it with 6AS7 output tubes. However, the upgraded 5U4GB is able to provide about 275ma and they are cheap. So for the good of the order, I will pick one up and add it to the list.

 
A short run for measuring purposes shouldn't hurt a 5U4G.  Daily use would greatly shorten its usable lifespan, but you wouldn't be so far over current that it would go poof or anything.  I accidentally ran my 45s at 200% of max plate current recently and they just shrugged.  I think the heat buildup is the key factor.  If I'd left them on that way for hours they'd probably be a little less fine I'm guessing.
 
I've run a 5U4G in my OTL and had no issue.  Didn't like the sound, but I never liked how a 5U4G sounded in anything personally.

 

[gibosi]

  A short run for measuring purposes shouldn't hurt a 5U4G.....

 
Today I ordered an RCA 5U4GB for $5 and when it arrives will measure both.

 

[gibosi]

  Today I ordered an RCA 5U4GB for $5 and when it arrives will measure both.

 
These arrived yesterday and last night I was able to calculate vdrop. Compared to common 5-volt rectifiers:
 
Rectifier                            Measurement    VDrop
 
HEXFRED    Glenn                256VDC          1VDC
GZ34 Sittard                         244VDC        13VDC
53KU Cossor                        234VDC        22VDC
GZ37 Mullard                       230VDC        27VDC
3DG4 Tung Sol                    240VDC        17VDC
GZ32 Mullard                       237VDC        20VDC
5R4GY RCA                        219VDC        38VDC
5AW4  CBS Hytron              229VDC         28VDC
 
5U4G RCA (1944)                212VDC         45VDC
5U4G RCA (1949)                184VDC         73VDC
5U4GB RCA (1963)              185VDC         72VDC
5U4GB Sylvania (D-getter)    227VDC         30VDC
 
The 1944 RCA is the older design with hanging filaments. The 1949 RCA appears to be identical to the one reviewed by Dubstep Girl. And both 5U4Bs have rectangular getters, so late 1950's to early 1960's. To say the least, I am very surprised that these four 5U4-types are so different.....

 

[gibosi]

I might be the only one with a Glenn OTL rolling 4-volt rectifiers with 6BL7/6BX7 output, so perhaps this rectifier is of little to no interest to anyone else but me?
 
Anyway, below is a Philips Miniwatt 1815. There appears to be a production code of some kind, "1C", but it does not conform with the codes used by Philips since 1948. The old code and the graphics style leads me to think this was manufactured in the mid-1940s in Eindhoven.
 
Edit: Oh, it has a vdrop of 28VDC.
 

 
And like the Hungarian Tungsram PV 200/600, this has four hanging filaments, instead of only two, which was much more common, for example, the 1944 RCA 5U4G.
 

 

[2359glenn]

The internals of this tube look like the PX4 except the PX4 has that crazy side contact base.
I use the PX4 in the EL3N amp and get a perfect 250 volts B+ with it

 

[gibosi]

  The internals of this tube look like the PX4 except the PX4 has that crazy side contact base.
I use the PX4 in the EL3N amp and get a perfect 250 volts B+ with it

 
Perhaps this is an AZ4?

 

[lukeap69]

The internals of this tube look like the PX4 except the PX4 has that crazy side contact base.
I use the PX4 in the EL3N amp and get a perfect 250 volts B+ with it

Glenn

What is the update on your EL3N amp? Are you going to send it to one of our members here for independent evaluation?

 

[2359glenn]

 

The internals of this tube look like the PX4 except the PX4 has that crazy side contact base.
I use the PX4 in the EL3N amp and get a perfect 250 volts B+ with it

Glenn

What is the update on your EL3N amp? Are you going to send it to one of our members here for independent evaluation?

Yes Still using it now.
Have to get the money to send it to some one.

 

[lukeap69]

 
Yes Still using it now.
Have to get the money to send it to some one.

 
Great.
 
How is the sound compared to the OTL and 300B?

 

[2359glenn]

 

 
Yes Still using it now.
Have to get the money to send it to some one.

 
Great.
 
How is the sound compared to the OTL and 300B?

Different then the OTL as it is a amp with output transformers and it can drive low impedance phones.
I think it sounds as good as the 300B just less power. Uses the same Lundahl transformers and high quality parts.

 

[raybone0566]

Different then the OTL as it is a amp with output transformers and it can drive low impedance phones.
I think it sounds as good as the 300B just less power. Uses the same Lundahl transformers and high quality parts.

Glenn,
Are you going to be offering this amp in the future? Very interested

 

[2359glenn]

 

Different then the OTL as it is a amp with output transformers and it can drive low impedance phones.
I think it sounds as good as the 300B just less power. Uses the same Lundahl transformers and high quality parts.

Glenn,
Are you going to be offering this amp in the future? Very interested

Yes
Might sell this one and build another.
Not the best for a tube roller not many tubes to roll only the older EL3 and different brands of EL3N tubes.