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I remembered reading an article regarding substituting 5U4G with 5V4G in Eico HF20 amplifiers somewhere in the internet. I wondered if anyone has tried it and with good results. Any input is appreciated.
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I second the advice to use a GE 5U4GB. It is my favorite of the 5U4 variants.
The GE sounds great, it's reliable and it's readily available at a decent price. I usually pay something in the $15 to $20 range.
Don't get hung up on the NOS label; I have bought a number of used GEs that have worked fine for many years. It is a workhorse.
Yes, I agree, they do an excellent job!
GE 5U4GB is the worst I heard both in black & brown base. Perhaps my monoblock PPP 6V6 triode connected amps just does not like the GE. Sylvania 5U4GB are close in sonic performance to the Tung Sol 5U4GB. Also RCA 5U4G are excellent.
~!
The Mind has No Firewall~ U.S. Army War College.
Use a Tung Sol 5u4GB. It is the best sounding 5U4GB.
Yes, the TungSol tube is good. Unfortunately, the price is (IMO) OTT. :> (
Eli D.
NOS at ebay for $15. Perhaps you are referring to the Tung Sol 5U4G.
Where did you find NOS for $15.00?? A few used maybe, but be VERY cautious about $15 "NOS" Tung-Sol 5U4GBs.
They are often relabeled, don't always trust the base print. They could be used. But really NOS? Hmm... I have my doubts.
A NOS Tung Sol 5U4GB with box is on ebay. $15 or best offer.
The only one I can see that meets your description never shows the tube, only the box. The box is marked "USED-OK" on the end flap. I'd be careful if I was considering that tube...
My goof- is used. Another NOS in box on ebay is $29.95 or best offer. I have bought a few new Tung Sol 5U4GB for around $15, but that was 10 years ago.
Personally, I would pay $30 for a NOS Tung Sol.
Best 5U4GB tone-wise and life expectancy. IME. I also like the USN-CHY CBS-Hytron BP 5U4GB.
Don't do it. Forward drop in a 5V4 is less than that in a 5U4. A 5V4 is good for 175 mA., while a 5U4 is good for 250 mA. A 5U4 can tolerate a larger 1st filter cap. than a 5V4.
If the "raw" B+ is taken off either pin 2 of the rectifier socket or a CT on the 5 VAC winding, installing a 5V4 will increase the residual hum level. :> (
Instead of believing WWW babble, check schematics and data sheets for yourself!
If you want to "roll" the rectifier, put an affordable NOS GE 5U4GB in and come back after 15+ years. ;> )
Eli D.
Thanks for the advise. I will definitely look into NOS 5U4G instead. Hopefully, the Eico HF20 will last for another 15 years.
NOT a 5U4G (ST bottle), but a NOS GE 5U4GB (straight bottle). NOS ST bottle 5U4s command silly amounts of money. The GE tube is more than adequate and carries a comparatively modest price tag.
Eli D.
If I am not mistaken the 5u4 is the stock rectifier tube for the HF20. Using a 5v4 would be similar in terms of voltage drop and also since it is an indirectly heated tube the B+ voltage will come up slowly like a 5ar4. If you are looking to drop the B+ you can use the 5r4 which should come in at about 20volts less. cheers, Dak
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