6EY6 Soon to Replace overpriced 6V6? (was: 6EZ6 & 6EY6? OPINIONS?)
Ted Matsumura
In order to be able to run the factory 6V6's, hotter newer 6V6's, these
6EY6's and 6EZ6's, as well as 6L6GC's, what kind of info. should I give
my amp tech on putting either a variable pot, or fixed selector bias
adjuster in place of the fixed resistor bias in my '62 deluxe.
Also, on the '59 tweed deluxe's, does the following make sense to run
6L6's:
* bias 6L6s at -48v.
* just leave the 250 ohm wirewound resister and replace 6V6 w/ 6L6GC
* Is it true that the only way one could get 48v on the bias would be to
change to fixed bias and that would be a formidible project, as the stock
'59 deluxe xformers don't have a tap for that?
Thanks for any tips, I just want to be able to experiment with the wide
variety of tubes out there for flexibility in tone.
Ted
In article <32D4E0...@nm-us.campus.mci.net>, murali@nm-
us.campus.mci.net says...
> Tremolux wrote:
> >
> > >>>Murali, Tremolux:
> > Would it be safe to try these 6EY6's in a brownface deluxe which has
> > fixed bias?
> >
> > Yes, providing that you have the bias reset. Your tech will have to
> > change a fixed resistor on the board in the amp's bias supply to get a
> > little more negative voltage on the grids. They should be biased at the
> > same idle current as a real 6V6. They work just fine and sound great.
> > Actually, the Tung Sol 6EY6s are quite a bit beefier in construction than
> > a 6V6. The 6EY6's fatter cathode should provide higher saturation current
> > as well!
> >
> > Tremo.
>
> I found that my Cathode Bias amps needed no bias change to accomodate
> the 6EY6, whereas my Fixed/Adjustable Bias amps needed to be adjusted
> with more negative bias to compensate for greater current draw on the
> magnitude of about 8ma. I'm in agreement with Tremolux (who got me
> going on this 6EY6 thing to begin with) that everything should be
> checked when switching tubes. Don't assume anything.
> m.
David Crittle
--
There are a number of valves with very similar or almost identical
characteristics to the 6V6. Check out the following types in your tube
manual: 6AQ5 / 6005 / EL90 / 7C5 / 6BW6 .....
None of these have an octal base, but I use them ALL in a Princeton
amp. Just make up an tube socket adapter for each type, and plug 'em
in !!
About changing from catode (self) bias to fixes bias...you don't
always need a transformer with a bias tap. Just try this...put two
resistors as a very low current (say 5 mA) *bleeder* across each side
of the HT secondary to earth. Then use two solid state rectifier
diodes connected as a full wave centre tapped rectifier, such that you
are rectifying a negative voltage. Filter this, and there is your
negatib=ve bias supply. If you can't quite picture this arrangement.
please email me for more details. Thsi works really well, maybe even
better than a single bias tap, because you end up with a full wave
rectifeid bias voltage, rather than a half wave.
It is common practice here in Australia when replacing the power
transformer in imported amps (our line voltage is 240 vac)
Hope this helps
Yours faithfully
David Crittle
RETROVOX
2 Burwood Street
WAGGA WAGGA
NSW 2650
Australia
Telephone /FAX:
Australia: (069) 25 2449
International: +61 69 25 2449
email: retr...@wagga.net.au
P.P.H. Bauwens
Ted Matsumura <te...@dnai.com> wrote in article
<MPG.d3f812c7...@news.dnai.com>...
<lines deleted>
> * Is it true that the only way one could get 48v on the bias would be to
> change to fixed bias and that would be a formidible project, as the stock
> '59 deluxe xformers don't have a tap for that?
Why would this be a formidable project? Just a negative supply with a
silicon
diode from one of the HT taps gives you -300 or something. A dropping
resistor
plus zener allows you to set any negative bias voltage you like. Remember,
only the potmeters and divider networks in the bias supply take a small
current,
not the tubes, so the above scheme is very practical. I used it myself.
The bias tap on the HT winding was just for an era where there were no
low-voltage stabilizers available.
You can easily calculate the total current drawn and the required dropping
resistor. It dissipates a little, but so what! Probably takes only a couple
of mA.
>
> Thanks for any tips, I just want to be able to experiment with the wide
> variety of tubes out there for flexibility in tone.
>
> Ted
>
<lines deleted>
--
Paul Bauwens
Rietkerkweg 364
3066VL Rotterdam
Tel: +31-10-4211858
Email: paul.b...@tip.nl
>
CHUCKtronic
Warning ! Both 6EY6 and 6EZ5 draw much more heater current than a 6V6.
Also for you all 6V6 replacement gurus, check out this site:
http://linux.cec.army.mil/cgi-bin/tube?tube=6EY6
Chuck.
David Crittle
If 6V6 tubes are too pricey for you, then find any of these types...
7C5, 6AQ5, 6005, 6BW6, EL90.
They all have identical plate characteristics to the 6V6. Max ratings
are a bit lower on the 6AQ5. I use type 6AQ5 with plate voltages up to
320.
Just make an adapter for the different socket, and plug 'em in. They
work fine, and they are much cheaper
--
Yours faithfully
David Crittle
email: retr...@wagga.net.au
Tremolux
>>>Warning ! Both 6EY6 and 6EZ5 draw much more heater current than a 6V6.
Yeah, Chuck, we know all about that.