Can u use 6L6's in place of 6V's to get more power

[nicksorenson]

Hi there,
In a cathode biased amp you can easilly swap the 6V6's with 6L6's without biasing. I know that. I also know you can burnout the OT. But assuming the power section is replaced is there a way to get a two power level amp by switching out tubes?

I have a deluxe with a OT prepared to handle the extra power but notice NO difference in power by plugging in the 6L's.

[Amp Kat]

In a Cathode biased situation you should hear a bit of difference in the extra 20 wattsb or so but then again after 20 or 30 watts of RMS it's sometimes hard to hear a SPL dB level change as it's usually only about-3dB and not much different of course it depends on the speakers also

[nicksorenson]

In a Cathode biased situation you should hear a bit of difference in the extra 20 wattsb or so but then again after 20 or 30 watts of RMS it's sometimes hard to hear a SPL dB level change as it's usually only about-3dB and not much different of course it depends on the speakers also

Yes you're right but I'd expect quite a bit more clean headroom. I've heard 30 watts before (lindy fralin amp, classic 30, even the deluxe reverb at 22 watts) and 12 watts as in the tweed deluxe and it barely has any clean headroom. Super quiet clean before it breaks up. Plenty loud distorted but clean is what I'm talking about. That's where I wonder if there's a way to do 6l's

[Richard]

It's possible that the phase inverter doesn't drive the power tubes hard enough to take advantage of the extra power. Could something in the power supply be holding your tubes back? Also I hear 6L6's are happier with a lower impedance that 6V6's, would this make a difference?

[nicksorenson]

It's possible that the phase inverter doesn't drive the power tubes hard enough to take advantage of the extra power. Could something in the power supply be holding your tubes back? Also I hear 6L6's are happier with a lower impedance that 6V6's, would this make a difference?

Hi Richard,
That's just it. I talked to Mercury Magnetics and asked that exact question about the power. The guy I spoke with said 6V's like to see 8k on the transformer and 6L's like around 5-6k. I guess I could add a speaker in parellel to do the same thing and kind of play a trick on the output tranny. Hmm, I'll have to try that.

[Richard]

I would still think you would get an increase in headroom, but maybe not as much. I've heard differing theories on what happens when the impedance is not optimum. I didn't notice a significant chance when I tried different speakers with my Princeton but I also used different speakers so I didn't really have a good standard of comparison.

[Rob Mercure]

You've probably heard this before but the relationship between power - wattage - and sound pressure at your ears isn't obvious. Your ears respond on a logarithmic scale while power is measured in a arithmatic manner. The old "rule of thumb" is that it takes a power increase of 10 to double the perceived sound level. You can only compare various amplifiers of various wattage when they all tested through the same speaker. A more efficient speaker has more effect on perceived sound level than the difference between a 6V6 and a 6L6! Looking at it another way - adding a more efficient speaker, or a second external speaker, may allow you to use a lower volume setting on a 6V6 and thus providing the impression of greater "headroom." While getting a good impedance match couldn't hurt the impedance a tube "sees" is the reflected impedance of the load so you can alter the load impedance and "match" the tranny to 6V6 or 6L6s.


Rob

[bob p]

Yes you're right but I'd expect quite a bit more clean headroom. I've heard 30 watts before (lindy fralin amp, classic 30, even the deluxe reverb at 22 watts) and 12 watts as in the tweed deluxe and it barely has any clean headroom. Super quiet clean before it breaks up. Plenty loud distorted but clean is what I'm talking about. That's where I wonder if there's a way to do 6l's

i'm not familiar with the fralin or the classic 30, but if you compare the tweed deluxe to a deluxe reverb, you're making a totally unfair comparison. the tweed deluxe is a dirty little amp, and the DR is not. if you're not happy with the amount of clean headroom in the 6V6 / 5E3 circuit, i'm not sure that you'd find the 6L6 / 5E5 to be that much better. Instead of looking for bigger bottles, maybe an amp with a different preamp/PI topology would better fit the bill.

[Joe]

Iv'e got a Crate GT-50 Stealth that has 4 6v6's and a 50 watt transformer. I've tried that and it it works well without mods by putting two 6l6's in the middle sockets. The 6l6's draw twice as much heater current as the 6v6's so if your amp has 4 6v6's you can swap easily with proper biasing, as long as you only use two 6l6's.

EH 6v6's are great by the way, they can handle twice as much voltage (450 volts i think) on the plates than the regular ones. I'd just get a new set of EH 6v6's if I were you, I've got a quartet of them in my amp and they're loud enough for me.

[Amp Kat]

Well once again your using a very close dB SPL analogy. 2- 6L6's is roughly 50 to 60 watts depending on tubes used and bias where 4- 6V6's is around 50 watts also. Now If you put 4- 6L6's in that same amp it would on paper be 100 to 120 watts and you would think you could hear a significant difference but as Rob was explaining and also the fact proven by the Fletcher/Munson guys that everyone hears a different SPL curve you may or may not be able to hear it. Of course the 4-6L6's in your amp is not a good thing for your power tranny or Output tranny but lets say you beefed both of them up with some Mercury's or comparable with overated specs then, it is possible that you would hear that significant difference as the output transformer wouldn't saturate under extreme conditions and you most likely would hear a good bit of SPL difference. The thing is the 6V6's wouldn't sound as good as the 6L6's. The two tube in the 4 slot works very well as I use two KT-88's in a 4 6L6 amp so go figure.

[MWJB]

Ideally to exploit any additional power when subbing 6V6s for 6L6's in a 5E3 style amp you'll need to bump up the B+ by using a tighter rectifier (GZ34/SS). This will also push up plate current so keep an eye on that (your PT will need to be able to handle the greater current draw too).

When you fit the 6V6s with the stock recto B+ will actually drop due to the higher current draw and increased cathode voltage, effectively negating any increase in headroom. You may notice differences in dynamics and frequency response.

A fixed/cathode bias switch would be a good idea if you're looking for headroom.

[Bruce / Mission Amps]

RIGHT ON my brother!!!
There is only about a 5-6 watt difference by popping 6L6s in over 6V6s and the only way to make this sound much more powerful with 6L6s is to increase the B+ rail with a stiffer rectifier, change the 4k7-5k1 screen node resistor to 2K2 and change the OT primary to 6K or less.
Any decent 5E3 OT will pass about +18 watts clean with a good amp setup, but with a stiffer rectifier, 6L6s, a 4K2 to 6K OT rated at 25 to 30 watts will let the amp make another 10-15 watts.
I can see about 24 to 26 watts out of my 6L6 modded 5E3 and it does sound louder and cleaner.
With the tone volume mod kit installed, it sounds like a totally different amp.

[Amp Kat]

I can see about 24 to 26 watts out of my 6L6 modded 5E3 and it does sound louder and cleaner.
With the tone volume mod kit installed, it sounds like a totally different amp.

No doubt that the one (5E3) that I built with your 6L6 trannies is so much louder than an original 5E3 it's not even close. It has kept up with many 50 to 100 watt marshalls with that amp and only two speakers. To much voltage though for 6V6's but sounds awesome until they red plate. How about a two rectifier voltage switch for 6V6/6L6 operation. I gotta try one of those volume/tone kits Bruce.

[Bruce / Mission Amps]

If you want some fun... pull a bias tap off the high voltage AC lead from the rectifier socket with a 100K to 220k resistor.
Build a cheap and dirty, brown face Deluxe type bias supply, lift the 6V6s's two 220K resistors from ground and feed the -Vdc there.
Set the idle current so the tubes are still running around 12 watts each.... you'll be pretty suprised at the difference.

[HTH]

If you want some fun... pull a bias tap off the high voltage AC lead from the rectifier socket with a 100K to 220k resistor.
Build a cheap and dirty, brown face Deluxe type bias supply, lift the 6V6s's two 220K resistors from ground and feed the -Vdc there.
Set the idle current so the tubes are still running around 12 watts each.... you'll be pretty suprised at the difference.

I did that with my own 6V6 amp and the fixed bias setting is quieter & cleaner than the cathode bias settings

I'm just happy that it totally rawks with the cathode bias setup.