nice looking 5u4g from EML in SSE?

[dubdub]

Hi All,


Well my Simple SE has been running for 12 months now and all is good and sounds great ( edcor power tranf 375-0-375 @ 175mA, transendars OPT +6550s tubes +obbigato oil 70uf oil cap) but I want to try out a few different tweaks/tubes.

I've come across this nice looking tube 5u4g from Emission Labs and I have read on the forum that 5u4gs have been used in simple SEs - any ideas or thoughts if it would be practicable to use this tube ?


5U4G Data sheet. Emission Labs.

Cheers for any advice

[rknize]

The 5U4 requires 3A from the 5V winding (the 5AR4 only needs 2A). As long as your power transformer can handle that, then it will be fine. Expect a lower B+ voltage with any of the 5U4 types...30-40V lower.

[tubelab.com]

Note the absolute maximum input capacitor value is 33uF. The standard input capacitor in the Simple SE is 47uF. Their required transformer resistance is higher than a 5AR4, it is likely that your Edcor has a lower resistance than their recommended values. At a minimum I would add an inrush current limiter in series with the power transformer center tap and reduce the value of the input cap. The Simple SE runs a 5AR4 pretty close to the maximum peak current. EML tubes aren't cheap, and I don't see a peak current rating in their data.

[dubdub]

Hi all

Thanks for the advice- I would have considered changing c1 to a smaller value but anything else Im not too sure now- all I'll end up doing is destroying a nice looking/ expensive tube! it would of made me laugh for about a minute then it would sink in ....very slowly...all that money gone up in sparks -damn!

Still Im going to look around for some nice rectifiers to experiment with (maybe nos?) any recomendations of types that could just drop in are much appreciated- thanks again

[dubdub]

just come across an interesting explanation from George tubelab on rectifiers and c1 value cap

Simple Simple SE questions


"Here is my real (overly) simple explanation:

The rectifier tube supplies the power for the entire amplifier. In the Simple SE this means that one tube must pass enough current to feed four tubes, so it has a tough job.

The filter capacitors store a reserve supply of energy to feed these four hungry tubes during times when they want more than the rectifier tube can deliver. They are completely empty when the amp is switched on. The amplifier tubes don't get to eat until the resovoir is full.

Now, upon flipping the power switch the four amplifier tubes get their wake up call, and can sit at the table awaiting the rectifier tube to feed them their breakfast.

The rectifier tube is slapped out of bed, told to immediately begin filling the resovoir before it is awake yet (cathode warmed up) so that the amplifier tubes can have their breakfast. If the resovior (first cap) is too big, the rectifier tube will have a heart attack before it can fill it!

OK, overly simple somewhat stupid explanation, but that is what happens. The rectifier tubes made today seem to be of a lesser quality than those made in the past. If the coating on the cathode is not of a uniform thickness, and the plate to cathode spacing is not constant, the problem is worse.

The rectifier tube must begin to pass current as it is warming up. If the spacing inside the tube is not uniform the current will flow in one localized area, leading to fireworks inside the tube. For this reason the first cap (C1) should be kept as small as possible. If a choke will be used, a 33, or 39 uF cap might be a better choice than a 47 uF."

[urmoo]

Originally Posted by dubdub

Still Im going to look around for some nice rectifiers to experiment with (maybe nos?) any recomendations of types that could just drop in are much appreciated- thanks again

What about some russian NOS tubes? Just one problem- they are directly heated tubes and its better to have an STB switch. Price is around 2-6$ each. http://www.cqham.ru/tubes/soviet/scan/5z3s.gif

[dubdub]

Urmoo thanks for the tip! Well I got some russian NOS and very impressed! sound is more crisper/cleaner (but slightly less bass but still good)- early days though=Very nice tube that Im trying with a pair of 6p3c...will load some pics up

[dubdub]

thanks everyone for the tips-very happy with this valve- good stuff!