Decware Zen Rectifier Tubes

[hoopsontoast]

I have a SE84CW (Export model?) with a variety of tubes.

Input - Mullard ECC88, Mullard 6922 (ECC88) and an Golden Dragon E88CC/6DJ8
Rectifier - WGTA 5Y3
Drivers - Edicron EL84 with some new Siemens EL83 coming next week

I quite fancy one of the 'Coke Bottle' rectifiers from an looks point of view, but which ones will be suitable?

I have seen the following mentioned for the SE84 series amps, which ones are likely to work best with the EL83's?

GZ32
5U4
5R4 (5R4GY)
5V4
5Y3 (5Y3G, 5Y3GT and 5Y3GB)

I really not sure what the differences are, can anyone shed any light?

Cheers, Rob

[BTH K10A]

Don't EL83's have a different pinout to EL84's

[camtwister]

Perhaps Rob intended to refer to the SV83, which is a legitimate swap for an EL84 in the SE84C.

The 5U4G rectifier commonly found in this amp has more of a coke bottle physique than the 5Y3.
I'd be tempted to push a 274B in the holder.
BEFORE doing that however, you must ascertain that your particular variant of the Zen Triode is able to rectify with a 274B, some require a modification to the adjacent capacitor.

[hoopsontoast]

I have bought a pair of some Siemens Rohre EL83, which I gather are the same as the SV83/6P15P-EV which are the tubes this amp is based around.
They are these-



Aparently it takes EL84 tubes as well without modification (like it has atm)

I had read that the 274B rectifier does need the modification.
I have asked over on the decware forum about the rectifier but its very quiet and only one reply.

http://www.decware.com/newsite/SE84C.htm

Thanks, Rob

[camtwister]

Hi Rob,

Yes, the SV83/6P15P-EV/EL84 can all be used as the power tube - one of the useful and neat design features of this Decware model, but they are not the same valves.

The EL84 has a different pin configuration. The suppressor grid and cathode connections ain't the same and this is why it does not support the Hazen modification. All of the above have different ratings for screen voltages, etc.

You probably know that the SV83 valve was designed for a linear response in video applications. The 6P15P-EV variant of this is a high specification tube with a gold grid, thicker glass and a 5000 hour rating. Most of these came out of the original Reflektor plant in Russia and Steve Deckert ships these as stock in the current version of your amp.

I have to admit that I thought the EL83 and SV83 are not different designations of the same device but are dissimilar enough to warrant care if considering swapping - even in this flexible amp, but I'm prepared to be proven wrong. That happens often!

So, back to rectifiers...
If you currently have a 5Y3, why not roll with a 5U4G and ascertain if you can hear a difference?

[camtwister]

Caveat emptor and all that, but a little research throws up these numbers.


SV83 - specified maximum plate dissipation: 12W, anode voltage: 300V, screen voltage: 200V

EL83 - max. plate dissipation: 9W, anode voltage: 250V, screen voltage: 250V

6P15P/EV - max. plate dissipation: 12W, anode voltage: 300V, screen voltage: 150V

EL84 - max. plate dissipation: 12W, anode voltage: 300V, screen voltage: 300V


As you can see from the data, only the EL83 has different power and anode voltage ratings, which backs up my hunch that the EL83 is not quite the same in character when compared to the 6P15P and SV83. The EL84 is assuredly different (but safe to use in the amp, as you know).

In isolation, none of this is useful unless you know what the circuitry around the tube is going to do when you throw the on switch. A short email to Steve at Decware requesting the designer's opinion will be preferable to noting my rambling suppositions. Nonetheless, I've whiled away a pleasant half-an-hour whilst listening to Ivory Joe Hunter.

[hoopsontoast]

Thanks for the very helpfull reply, lots of info there!
I have sent Decware an email, I just assumed that the EL83 tubes would work as they are often put in the same category SV83/6P15P/EL83.

[camtwister]

You're welcome.
Please share Steve's response.

If this pursuit is not too perverse for you, take a look at the data sheets below. In the case of the SE84 amp (in which pentodes are wired as triodes and run in single ended Class A operation), the significant chewy bit in terms of valve choice between the EL84 and SV83 is that the SV83 does not have the G3 suppressor grid connected internally to the cathode.

Although the answer is in there somewhere, at this moment I haven't a clue what goes on inside an EL83.
In the same fashion, I'm not sure what's inside a girl.

http://www.mif.pg.gda.pl/homepages/f...s/SV83spec.pdf

http://tubedata.milbert.com/sheets/113/6/6P15P.pdf

http://www.mif.pg.gda.pl/homepages/f...020/e/EL83.pdf

http://www.mif.pg.gda.pl/homepages/f...163/e/EL84.pdf

~

[hoopsontoast]

Thanks, I have no idea, about the tubes. Will see what Steve says

[hoopsontoast]

Well I got them home, plugged them in and....

....well not much, no output from the left channel at all, an the right was very quiet and distorted.

I guess its either a bad pair of tubes, or they are not compatible.