Yes, the principles are the same:
Tube: u, rp, Gm
Capacitor Xc = 1/(2 x pi x F x C)
Inductor XL = 2 x pi x F x L
Etc.
The performance specifications often are not the same:
Wide frequency response / Narrow frequency response
Low distortion / High distortion
Low hum / Medium hum
Gain to deal with modern signal source voltages / gain to deal with electric guitar voltages
Etc.
Teach someone to build a guitar amplifier, and he/she will have a guitar amplifier.
just my opinions
Tube: u, rp, Gm
Capacitor Xc = 1/(2 x pi x F x C)
Inductor XL = 2 x pi x F x L
Etc.
The performance specifications often are not the same:
Wide frequency response / Narrow frequency response
Low distortion / High distortion
Low hum / Medium hum
Gain to deal with modern signal source voltages / gain to deal with electric guitar voltages
Etc.
Teach someone to build a guitar amplifier, and he/she will have a guitar amplifier.
just my opinions
What you say is valid, however Merlin's site has a lot of info on the basics, how to bias a valve, frequency calculations etc. As already mentioned the outcome is different but the principles are the same. Also Merlin deals with grounding, designing a PSU, SE and PP OP stages, distortion etc etc.
Therefore for a potential builder/designer of valve amps the site is one of the best for a beginner. No other site I'm aware of deals with first principles in such an easy to understand way. I was able to design and build a SE 3w amp without any knowledge of valves; the result may not have been 100% correct but I learned a hell of a lot by reading the info on the site mentioned and hands on practical building.
My recommendation still stands, Andy.
Therefore for a potential builder/designer of valve amps the site is one of the best for a beginner. No other site I'm aware of deals with first principles in such an easy to understand way. I was able to design and build a SE 3w amp without any knowledge of valves; the result may not have been 100% correct but I learned a hell of a lot by reading the info on the site mentioned and hands on practical building.
My recommendation still stands, Andy.
One of my Grandsons has a PV JSX. The build quality is first class. And it does very well on the test bench.
Attachments
It is bigger than what you are looking at, but the KT88 - Single Ended Tube Amplifier Build 2018 - Part 1 - YouTube amp is excellent. It was my first build and I did it before the walk through video existed. I've been using it for around 8 years and have yet to find anything that sounds better. And I've run it up against some amps that are well known on here.
I haven't heard this amp but it is smaller and has a very detailed series of build videos
6BM8 DIY Scratch Built Tube Amplifier - YouTube
I haven't heard this amp but it is smaller and has a very detailed series of build videos
6BM8 DIY Scratch Built Tube Amplifier - YouTube
invaderzim,
Good calls.
Good 'first time' amplifiers.
The Original Michael Abdellah amp is good, and you can have your pick of several Beam Power output tubes, or an EL34 Pentode (strap pin 1 to pin 8);
Or build the Schade negative feedback modification to the Michael Abdellah amp . . .
One comment about safety, for 3 wire power mains that have Hot, Neutral, and Ground (US for example):
IEC socket connector on the amplifier:
Hot wire directly to the fuse.
Fuse directly to the On/Off switch.
On/Off switch to the power transformer primary
In that order, Safety First!
If the switch breaks and connects to Ground or Neutral, the fuse will blow.
If any wire contacts Ground or Neutral, the fuse will blow (other than the wire from the Hot IEC lug, or the Hot end of the fuse).
Some IEC socket connectors even have the fuse holder built-in.
The 6BM8 amplifier schematics are in more than one thread on Tubes / Valves; just pick one of the better ones.
Good calls.
Good 'first time' amplifiers.
The Original Michael Abdellah amp is good, and you can have your pick of several Beam Power output tubes, or an EL34 Pentode (strap pin 1 to pin 8);
Or build the Schade negative feedback modification to the Michael Abdellah amp . . .
One comment about safety, for 3 wire power mains that have Hot, Neutral, and Ground (US for example):
IEC socket connector on the amplifier:
Hot wire directly to the fuse.
Fuse directly to the On/Off switch.
On/Off switch to the power transformer primary
In that order, Safety First!
If the switch breaks and connects to Ground or Neutral, the fuse will blow.
If any wire contacts Ground or Neutral, the fuse will blow (other than the wire from the Hot IEC lug, or the Hot end of the fuse).
Some IEC socket connectors even have the fuse holder built-in.
The 6BM8 amplifier schematics are in more than one thread on Tubes / Valves; just pick one of the better ones.
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coldcut,
Some other good amplifier schematics in this thread are:
artosalo's Post # 6 EL34 in Triode mode (strap EL34: pin 1 to pin 8).
Will also work well in Ultra Linear, if you have a transformer that has a UL tap.
Diabolical Artificer's Post # 11 EL84 in Pentode mode, but not very good damping factor.
If you use perhaps a 5k transformer, and Triode wire it, there will be less power, but higher damping factor, and lower distortion;
Or use a 5k transformer with a UL tap, and wire it in Ultra Linear mode (medium power, medium damping factor, and medium distortion).
As you can see, there are any number of simple but good tube amplifier circuits.
Some other good amplifier schematics in this thread are:
artosalo's Post # 6 EL34 in Triode mode (strap EL34: pin 1 to pin 8).
Will also work well in Ultra Linear, if you have a transformer that has a UL tap.
Diabolical Artificer's Post # 11 EL84 in Pentode mode, but not very good damping factor.
If you use perhaps a 5k transformer, and Triode wire it, there will be less power, but higher damping factor, and lower distortion;
Or use a 5k transformer with a UL tap, and wire it in Ultra Linear mode (medium power, medium damping factor, and medium distortion).
As you can see, there are any number of simple but good tube amplifier circuits.
Phew! Lots of info to digest
I have all summer to make a decision
If you want to start building in the fall and the required output transformers are not trivial or come from China to save money, the right time to place your order may be now. If you decide for high quality transformers, for example with C core, you can choose higher wattage tubes like EL34, 6L6 or maybe KT88 because the total cost of the project will be almost the same as a low power one. Unless 2-3 W is enough for you anyway, of course.
Hi all,
Reading through your comments above has just completely changed my plans about building a Mullard 3-3 amp as a first-timer. (I was looking at the heated cathode solution too.. )
Could someone just put me in the right direction where to find more details of the EL34 design artosalo posted in #6 please? I know that most of you guys can see the BOM in your mind straight away just by looking at this schematic. However, I feel uncertain about quite a few things like capacitor details (Electrolytic / Film / Silver Mica, voltage withstand), resistor details (type, tolerance, voltage withstand), output transformer type etc. Also, I am not sure about the power circuit, what transformer and tube to use.
Apologies for the very entry level questions, just has to start somewhere 🤷♂️
Thanks,
Laszlo
Reading through your comments above has just completely changed my plans about building a Mullard 3-3 amp as a first-timer. (I was looking at the heated cathode solution too.. )
Could someone just put me in the right direction where to find more details of the EL34 design artosalo posted in #6 please? I know that most of you guys can see the BOM in your mind straight away just by looking at this schematic. However, I feel uncertain about quite a few things like capacitor details (Electrolytic / Film / Silver Mica, voltage withstand), resistor details (type, tolerance, voltage withstand), output transformer type etc. Also, I am not sure about the power circuit, what transformer and tube to use.
Apologies for the very entry level questions, just has to start somewhere 🤷♂️
Thanks,
Laszlo
Chis already mentioned most important issues with this design. . Poor open loop frequency response, far too high negative feedback, still far too high sensitivity. EF86 operates at starving voltages. If you have well equipped lab, then go ahead. If not, something more straightforward is my recommendation.
Something like this:
Tubelab SSE could be an option. Well supported here, with many satisfied builders.
Here is a recent thread ...
Tubelab SSE
Here is a recent thread ...
Tubelab SSE
The TubeLab SPP (EL84s in push-pull) uses smaller (less expensive) transformers and even though it uses more tubes the total tube cost should be less. It's possible to build it with tube rectifier or SS rectification. It's kind of a simplified Mullard 5-10. I've built a few. No drama, they just work well. Ongoing build thread below but there are other build threads too.
Cheers, S.
https://www.diyaudio.com/community/threads/tubelab-spp-first-timer-build.388172/
Cheers, S.
https://www.diyaudio.com/community/threads/tubelab-spp-first-timer-build.388172/