My favorite "real world" amplifiers use EL34s in push-pull UL - 50Ws is enough power to drive moderate efficiency speakers, while providing full-range sound. A well-designed circuit, power supply - and good iron, of course - makes a big difference in the end result.
I also, however, have a real love for single-ended pentode amplifiers with regulated screens. With fixed bias and some (the horror!) negative feedback, my personal tastes actually prefers this to any of the SETs - 300Bs and 2A3s - I have built in the past... really! Plug in some good 6550s or EL34s, and they can really rock too. Of course the power out is slightly more than your average 300B amp, and the feedback helps too for controlling a 15" woofer.
If I am going to do triode, I would probably do 2A3/6B4G/300B in push-pull - just to get the power I need for my UREI 813As.
I also, however, have a real love for single-ended pentode amplifiers with regulated screens. With fixed bias and some (the horror!) negative feedback, my personal tastes actually prefers this to any of the SETs - 300Bs and 2A3s - I have built in the past... really! Plug in some good 6550s or EL34s, and they can really rock too. Of course the power out is slightly more than your average 300B amp, and the feedback helps too for controlling a 15" woofer.
If I am going to do triode, I would probably do 2A3/6B4G/300B in push-pull - just to get the power I need for my UREI 813As.
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Yes, I did, and I have played my guitar through a Tubelab SE running 300B's and Electra print OPT's several times. It has a nice clean tone and runs into a sweet bluesy sound when pushed into the distortion zone. You can make a good guitar amp out of most any tube.
The metallic sound referred to has a lot more to do with the OPT and speaker choices than the tube choice. As stated DHT's are not rugged enough for guitar amp use.
The tube choice for a guitar amp is based on two criteria.....watts per dollar and availability. Years ago one could find guitar amps with all sorts of unique tubes in them. Now there are about 6 to 10 type numbers that can be found at local music stores. If you are building a guitar amp for commercial sale, and you want to be succesful, you MUST use these types.
If you are making a one off for yourself or a friend, you can use anything you want.....I prefer TV tubes, It's the watts per dollar thing. I can get 125 watts for $10 worth of tubes.
Back to the original question. I have always said "EL84's rock, 6V6's sing the blues." This was from a guitar amp perspective. I have used both and zillions of other tubes for HiF and come to this concluson. Want 95% of the sound of a high dollar SE 45 amp? It is easy, use a trioded 6V6 through a pair of $20 Edcor XSE 15-8-5K OPT's. You will get a very nice sounding 2 WPC with a frequency response from 25Hz to 45KHz. If 2 WPC is enough and you like the low cost, there is no question.....just do it. The only thing better in that power level involves DHT's and a lot more money.
Thousands of "HiFi" sets in the 1950's (especially Magnavox) used a pair of P-P 6V6's to make 10 to 15 watts. They also sound very nice.
6L6 types (including the 807) offer more power, but the linearity isn't as good. 6L6's in SE will generate quite a bit of 2H and some of this can be cancelled with an equally non linear driver tube in a 2 stage amp. These tubes do work best in a P-P amp and benefit from some type of feedback, either global or local to the output tube (Schade type).
FWIW, the 6AS7 is a double triode, and the OTL amp circuits I've seen that use them (Bruce Rosenblit's) use the two triodes in the envelope in a push-pull configuration, such that each individual tube is a 'pair'. I assume that's how the Atma-Sphere amp uses them, too, so the odd number of them would still be balanced.
I'm planning to put something together with P-P 1625s at some point, to stay semi on-topic.
-Pat
I'm planning to put something together with P-P 1625s at some point, to stay semi on-topic.
-Pat
The reason why I asked the question is that I have 2 SE output trafos of good quality (I have used them before with 6B4G´s)and a power trafo that would fit.
And I might use them with a 110db treble horn with DSP Xover.
Is 6v6 that outstanding in middle/treble?
The opt is 3,5-4kohm.
And I might use them with a 110db treble horn with DSP Xover.
Is 6v6 that outstanding in middle/treble?
The opt is 3,5-4kohm.
All the discussed tube types can work from DC to some 60 MHz
with quite similar linearity and frequency response.
The final outcome depends on the whole circuit, not the tube.
^This.
It should be obvious that when you have a circuit designed for a certain type of tube fitting in another type will change the performance of the circuit and that will often have audible effects.
Say, a tube will have a characteristic curve of operation, internal capacitances and resistances. These will vary from tube to tube and even amongst same models there's quite a lot of "spread". Changing tube to another tube with different internal resistance will undoubtebtly affect things like frequency response because of the RC circuit of the coupling, similarly as changing R in a RC filter will have. Same thing with internal capacitances. Also, tubes are biased on a certain load line and fitting in another tube will therefore effect the transfer curve of the stage, even if you rebias because different tubes have different characteristic curves.
Most just try different tubes without even considering compensating the circuits for the given tubes. This practically changes the circuit because tube's parameters are part of the circuit as well. Say, take a power tube: it preferably needs to be inpedance matched to the reflected primary impedance of the OT. What happens when you fit in another tube with different internal impedance? The impedance match is altered and the amplifier's damping factor will change. When you drive a reactive load this again will affect the frequency response. Say, the tube has different gain and different requirements for grid drive signal. Fit in another tube with different parameters and things change again...
But that's not "sound of tubes", that's just sound of the circuit reconfigured differently. In another, different circuit the same replacement might actually ave very different effects, or perhaps no considerable effects at all. It all depends of the surrounding circuitry.
It should be obvious that when you have a circuit designed for a certain type of tube fitting in another type will change the performance of the circuit and that will often have audible effects.
Say, a tube will have a characteristic curve of operation, internal capacitances and resistances. These will vary from tube to tube and even amongst same models there's quite a lot of "spread". Changing tube to another tube with different internal resistance will undoubtebtly affect things like frequency response because of the RC circuit of the coupling, similarly as changing R in a RC filter will have. Same thing with internal capacitances. Also, tubes are biased on a certain load line and fitting in another tube will therefore effect the transfer curve of the stage, even if you rebias because different tubes have different characteristic curves.
Most just try different tubes without even considering compensating the circuits for the given tubes. This practically changes the circuit because tube's parameters are part of the circuit as well. Say, take a power tube: it preferably needs to be inpedance matched to the reflected primary impedance of the OT. What happens when you fit in another tube with different internal impedance? The impedance match is altered and the amplifier's damping factor will change. When you drive a reactive load this again will affect the frequency response. Say, the tube has different gain and different requirements for grid drive signal. Fit in another tube with different parameters and things change again...
But that's not "sound of tubes", that's just sound of the circuit reconfigured differently. In another, different circuit the same replacement might actually ave very different effects, or perhaps no considerable effects at all. It all depends of the surrounding circuitry.
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There are enough choices of tubes that you will go around in circles 🙂
Another tube that I have heard as a driver (very nice) and have seen used as an output tube for treble is the Russian 6E5P (triode wired) - do a web search for "Romy the Cat 6E5P". I believe this tube to be more linear than the 6V6 (triode wired).
Nothing beats 4П1Л in triode mode.
6V6 is good, it was designed for SE audio output stages. 6L6 (and 807) were designed for transmitters. They are less linear, but for PP with negative feedback are Ok.
6P15P in triode is also very good.
6V6 is good, it was designed for SE audio output stages. 6L6 (and 807) were designed for transmitters. They are less linear, but for PP with negative feedback are Ok.
6P15P in triode is also very good.
Hi,
You certainly won't find that one in a guitar amp for sure....
That said, very few tubes were designed with audio use in mind.
Most certainly not the typical tubes you'd find in the output stage of an OTL amp.
OTOH, the EL34 was designed with audio in mind. The there's the KT77 and the fat bulb 6CA7 as well...
Anyway, the 6V6GT (AKA the barn tube) and its cousins are great sounding little devils when triode strapped.
F2A or EL158 anyone?
Ciao, 😉
You certainly won't find that one in a guitar amp for sure....
That said, very few tubes were designed with audio use in mind.
Most certainly not the typical tubes you'd find in the output stage of an OTL amp.
OTOH, the EL34 was designed with audio in mind. The there's the KT77 and the fat bulb 6CA7 as well...
Anyway, the 6V6GT (AKA the barn tube) and its cousins are great sounding little devils when triode strapped.
F2A or EL158 anyone?
Ciao, 😉
no similarity whatsoever but....the EL36 is mentioned in some forums as a "poor man's 300b" wonder why is that if it is even true....😀
EL36 in triode. Not as a pentode Tom S. did curves for it in this format - do a search on the forum
Yes I have those curves.
I was thinking of this schema:
It`s from:EL36: Applications in Audio
Surely one more stage is needed before for normal linelevels input (2v)?
I was thinking of this schema:
It`s from:EL36: Applications in Audio
Surely one more stage is needed before for normal linelevels input (2v)?
So true.
Anyway,if we are talking about triode output, there are not many choices: 6550/Kt88 of El34. Triode strapped are good for some 7-8 watts before clipping.
807/6L6/6V6: 2-3 watts as triodes, because of the 300v screen grid voltage limit.
P.S: There are no guitar amp tubes. All of the above are audio tubes used also in guitar amplifiers.
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