Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Shack on June 30, 2015, 06:27:19 pm
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If I just put a GZ-34 and 2 6l6 in my deluxe without changing any filter caps or output tranny ......using the same cathode resistor and cap.....will it hurt anything, cause it sounds pretty tough,lol
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It could. Does yout pt have enough ma to run 6l6? If not it will probably fry.
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It COULD hurt something,
The heater current on both those tubes is much greater than a 5Y3 and 6V6. Watch the power transformer for heat. Since you're not increasing voltage much, nor changing bias resistors for a much greater output, you're not likely hurting the output trans, but that power tranny will likely suffer greatly under that loading on the heater windings.
A good indication would be to check the 6.3v on heaters with the 6V6 then the 6L6. An appreciable drop in voltage would indicate excess loading.... also the 5v heater winding to the rectifier, but use caution when measuring that, because that 5vac is "riding" atop the full B+ voltage.
**Ed beat me to the punch on this reply.
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The heater current on both those tubes is much greater than a 5Y3 and 6V6.
5Y3 actually draws more filament current than the GZ34.
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The heater current on both those tubes is much greater than a 5Y3 and 6V6.
5Y3 actually draws more filament current than the GZ34.
I stand corrected Steve, thanks. I didn't remember, and didn't look it up, it was ASSumption :)
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was gonna say that 5y3 draws more current than gz34 too....but....I have a p-tf41316 in there and think the heater current is good ....I also liked the gz 34 with the 6v6....and the plate voltage isnt much different than a deluxe reverb.....still high....just didnt wanna play around with tubes if I was going to hurt anything....dont got the bucks if I do,lol
was thinkin about buyin trannys to use 6l6 in the 5e3, and use the deluxe trannies for a princeton reverb build :)
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If you are going to use the 6L6 long term you really should bump up the power tube cathode resistor and bypass cap to 10 watt resistor and 50 volt rated cap.
Also if you have a multi-tap output transformer you can give the 6L6 a better load match by plugging an 8 ohm speaker into the the 16 ohm speaker tap. For a 4 ohm speaker you would use the 8 ohm speaker tap.
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Do change the cathode bias resistor to 10 watt and around 225 ohms/250 other than that do what robrob suggests if you have a multi tap OT.
I did these changes but have a switch for 6L6 and 6V6, the switch changes the dropping R valve thus the voltages down the rail, higher.
Touch the PT when you've been playing for excessive heat, if it hot, take the 6L6's out you'll need a bigger PT if you want to use them.
Also changing the OT to a bigger wattage would also help.
al
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Yea, I plan on changing the cathode resistor/cap and OT.....the power tranny has 3A of filament current and 3A for rectifier.....so all good, I just wanted to make sure that I could use it this way while I get the parts to make it either switchable or permanent
Thx alot everyone
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No harm, only thing is your bias resistor is 5 watts, 6L6's need a 10 watt cement resistor or the like, probably won't blow for a while if it does but do get a 10 watt.
You could easily put in a switch wired for two dropping resistors, one for 6L6's and one for 6V6's that way you could go back to 6V6's by just replacing the tubes, flip the switch and change the speaker tap, like robrob mentioned above. That's important as it will let the tubes see the correct impedance. If you get an OT for 6L6's with 4 and 8 ohms taps (4K) use the correct tap for the speaker you are using and then when using 6V6s, use the the unmatched tap and the 6V6's will see 8K from the OT. I did this in my 5E3, bigger OT with 4 and 8 ohms tap, the switch to increase voltages down the rail and a 10 watt bias resistor, that all you need if your PT can handle 6L6s.
al
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No harm, only thing is your bias resistor is 5 watts, 6L6's need a 10 watt cement resistor or the like, probably won't blow for a while if it does but do get a 10 watt.
Depends on the current that's pulled through that R.
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The Fender 5E5 Pro (not 5E5-A) uses 6L6's with a 250 ohm 10 watt cathode resistor. Voltage drop across the cathode resistor can easily exceed 25 volts so the bypass cap should be a 25uF 50 volt.
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Another thing, when you replace the bias cap with a 50v, use a higher uf value as this will tight'n up the bass. You can go as high as 1000uf @ 50v but 500uf should be fine. IMO, 25uf's is low.
al
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thx for the tips, and robs 5e3 mod page has all that and more so I wont forget in case I lose this thread :) So I can play around with it until I order the parts from Doug
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The Fender 5E5 Pro (not 5E5-A) uses 6L6's with a 250 ohm 10 watt cathode resistor.
Yes, but the 5E5 Pro has a larger PT that puts out more B+ current than the 5E3 PT.
The power tubes are limited by the PT's B+ and current and OT's primary impedance. Putting in bigger power tubes with greater output capabilities in the same amp will not output more because of the same iron set.
In other words, putting in 6L6's in an amp designed for 6V6's, the 6L6's can't really draw any more current than the 6V6's because of the PT/iron set.
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Yes, but the 5E5 Pro has a larger PT that puts out more B+ current than the 5E3 PT.
The power tubes are limited by the PT's B+ and current and OT's primary impedance. Putting in bigger power tubes with greater output capabilities in the same amp will not output more because of the same iron set.
In other words, putting in 6L6's in an amp designed for 6V6's, the 6L6's can't really draw any more current than the 6V6's because of the PT/iron set.
Yes, I agree and all those issues are handled in the 5E3 6L6 upgrade: https://robrobinette.com/5e3_Modifications.htm#6L6_Upgrade (https://robrobinette.com/5e3_Modifications.htm#6L6_Upgrade)