Hello all, newbie here.
I am contemplating building my first stereo hifi tube amplifier. I've been reading up on (guitar) tube amplifiers, watched way too many youtube clips and have (succesfully) built two guitar amps (Marshall JTM45 and JCM800). Despite that I find it hard to get started in the hifi amp world and that is the reason for this post.
I've got lots of question, but I'll limit myself to a few. Here they are: What amp do you guys suggest I should build? Are there any informative build threads or sites? Any must read books, articles or websites? I've read both tube preamp book by Merlin Blencowe and the power amp book by Richard Kuehnel.
Any advice is welcome. Thanks in advance.
I am contemplating building my first stereo hifi tube amplifier. I've been reading up on (guitar) tube amplifiers, watched way too many youtube clips and have (succesfully) built two guitar amps (Marshall JTM45 and JCM800). Despite that I find it hard to get started in the hifi amp world and that is the reason for this post.
I've got lots of question, but I'll limit myself to a few. Here they are: What amp do you guys suggest I should build? Are there any informative build threads or sites? Any must read books, articles or websites? I've read both tube preamp book by Merlin Blencowe and the power amp book by Richard Kuehnel.
Any advice is welcome. Thanks in advance.
You'll need this. And no carbon comps. Audio amplifiers are very different from guitar amps,
since they are not supposed to add distortion or coloration.
http://hifisonix.com/wordpress/wp-content/uploads/2019/02/Ground-Loops.pdf
since they are not supposed to add distortion or coloration.
http://hifisonix.com/wordpress/wp-content/uploads/2019/02/Ground-Loops.pdf
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That pdf should keep me busy for some time...
Btw, no carbon comps in my guitar amps; only metal oxides (power supply) and metal films.
Speaker have yet to be bought. Advice on them is also welcome. Room is L shaped; Total is 6m x 8m, the leg I'm sitting in is 4m x 3.5m. It would be nice if the music would have some oompf, but I don't wanna upset my neighbours. My favorite music is blues and rock. My JTM45 was a kit I tweaked, my JCM800 was completely scratch build. I like that thought. Budget range is a couple of hundred euros for the amp, keeping in mind I also have to buy some speakers.
I think a Tubelab SPP or Tubelab SSE are good starting points. They are not complicated, so you can understand the philosophy of tube hifi, and they can be adapted to different tubes, and budgets.
I built the SPP, then I built it again point-to-point, so you can take a proven design, and learn how to adapt it to be built in a traditional way, sharing the bulk of the expensive components.
The hardest part is making a presentable and electrically safe case. Bearing that in mind, there are some very reasonable Chinese origin kits that are complete, e.g. Boyou, and a lot of discussion here on improvements.
Another tack is to buy something classic in need of attention, e.g. Quad 2’s, and get them running, learning along the way.
It is a hobby that satisfies all of the senses, and benefits from lots of skills.
I built the SPP, then I built it again point-to-point, so you can take a proven design, and learn how to adapt it to be built in a traditional way, sharing the bulk of the expensive components.
The hardest part is making a presentable and electrically safe case. Bearing that in mind, there are some very reasonable Chinese origin kits that are complete, e.g. Boyou, and a lot of discussion here on improvements.
Another tack is to buy something classic in need of attention, e.g. Quad 2’s, and get them running, learning along the way.
It is a hobby that satisfies all of the senses, and benefits from lots of skills.
Tom Kamphuys,
You want speakers with a reasonably flat impedance curve, as tube amps do not exhibit the gargantuan damping factors seen in SS amps.
Paul Joppa has provided the community with a useful rule of thumb, for mating amps and speakers. Joppa's Rule states that for "typical" listening spaces an amp speaker combo should be capable of producing 102 dB. SPL peaks at a 1 M. distance.
You want speakers with a reasonably flat impedance curve, as tube amps do not exhibit the gargantuan damping factors seen in SS amps.
Paul Joppa has provided the community with a useful rule of thumb, for mating amps and speakers. Joppa's Rule states that for "typical" listening spaces an amp speaker combo should be capable of producing 102 dB. SPL peaks at a 1 M. distance.
Keep in mind that Tom wants the cost of the amplifier to be no more than 200 Euros.
Some of you in Europe know what kind of low cost power and output transformers are available.
It might be less expensive to purchase a push pull output transformer and two EL84 per channel,
instead of purchasing a much larger single ended output transformer (for equal bass response) and one EL84 per channel.
Or, if Tom wants to do it that way, build a mono-block amp this year, and build a second mono-block amp next year, for example, when budget permits.
Some of you in Europe know what kind of low cost power and output transformers are available.
It might be less expensive to purchase a push pull output transformer and two EL84 per channel,
instead of purchasing a much larger single ended output transformer (for equal bass response) and one EL84 per channel.
Or, if Tom wants to do it that way, build a mono-block amp this year, and build a second mono-block amp next year, for example, when budget permits.
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You can get two top quality output transformers and a power transformer for a PCL86 push pull amplifier for €200 ...
toroidy.pl TTG-ECL86PP-Tube-output-transformer-10kOhm-2xECL86-2xPCL86-Push-pull-or-similar
The tubes can be had for €20, then if you search out ECL86 and Dissident Audio, then you have a fine amplifier.
At the other end of the scale, a pair of 112v twin primary toroidal with 9v secondaries would make adequate OPTs for a push pull project, and keep total cost under €200.
Or take it even further. There is still a lot of cheap tube powered gear to be had. I picked up an old Panasonic amp from the 60’s for €100, and it will make a fine integrated amp with 6AR5 outputs.
If you monitor the local auction sites, and then it does not have to be prohibitively expensive to produce something of reasonable quality.
toroidy.pl TTG-ECL86PP-Tube-output-transformer-10kOhm-2xECL86-2xPCL86-Push-pull-or-similar
The tubes can be had for €20, then if you search out ECL86 and Dissident Audio, then you have a fine amplifier.
At the other end of the scale, a pair of 112v twin primary toroidal with 9v secondaries would make adequate OPTs for a push pull project, and keep total cost under €200.
Or take it even further. There is still a lot of cheap tube powered gear to be had. I picked up an old Panasonic amp from the 60’s for €100, and it will make a fine integrated amp with 6AR5 outputs.
If you monitor the local auction sites, and then it does not have to be prohibitively expensive to produce something of reasonable quality.
€400-500 is quite sufficient to complete an approx. 15 WPC push/pull amp based on "12" W. tubes, like the EL84 and 6V6. Mate the amp to low 90s sensitive speakers and the music will flow.
BTW, a well executed "full wave" voltage doubler is the economical way to obtain a high performance B+ PSU. Good sized caps. in the stack followed by a LC section reservoir get the job done, well. Hint: Hegeman, Marantz, and McIntosh used the method.
BTW, a well executed "full wave" voltage doubler is the economical way to obtain a high performance B+ PSU. Good sized caps. in the stack followed by a LC section reservoir get the job done, well. Hint: Hegeman, Marantz, and McIntosh used the method.
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Tom,
This affordable O/P transformer (approx. €50) is "perfect" for "12" W. multi-grid "finals".
This affordable O/P transformer (approx. €50) is "perfect" for "12" W. multi-grid "finals".
Thanks for the output transformer links. I've added them to my list of interesting suppliers.
What is the reason choosing PP? Is (was) it the budget? The music I'd like to listen to? The room size?
And I'm still searching for schematics of good simple amps, preferably with some explanation. The schematics I do find look different from the guitar amps I'm used to. Other tricks, other tubes. Is there a book you guys can recommend?
What is the reason choosing PP? Is (was) it the budget? The music I'd like to listen to? The room size?
And I'm still searching for schematics of good simple amps, preferably with some explanation. The schematics I do find look different from the guitar amps I'm used to. Other tricks, other tubes. Is there a book you guys can recommend?
€400-500 is quite sufficient to complete an approx. 15 WPC push/pull amp based on "12" W. tubes, like the EL84 and 6V6. Mate the amp to low 90s sensitive speakers and the music will flow.
BTW, a well executed "full wave" voltage doubler is the economical way to obtain a high performance B+ PSU. Good sized caps. in the stack followed by a LC section reservoir get the job done, well. Hint: Hegeman, Marantz, and McIntosh used the method.
I have Blencowe's hifi book. I'm planning on using one the power supply examples.
In any power handling range, push/pull "iron" costs less than the SE stuff.
All sorts of signal topologies are available to chose from. "Baby Huey", "El Cheapo", and the Dyna ST-35 are some of them.
You will be very hard pressed to find a more economical high performance setup for the B+ PSU than "full wave" doubling a boosted Triad N-77U with UF5408 diodes.
All sorts of signal topologies are available to chose from. "Baby Huey", "El Cheapo", and the Dyna ST-35 are some of them.
You will be very hard pressed to find a more economical high performance setup for the B+ PSU than "full wave" doubling a boosted Triad N-77U with UF5408 diodes.
Eli,
That is a good way to get the B+.
But just be sure to keep all of the doubler circuit in a local loop. Extending it out to
other areas of the amplifier, it will cause terrible hum/hum upper harmonics noise.
But it requires one more tran$former, the filament tran$former.
Choke input full wave with center tap, or with bridge, has the quietest hum/hum upper harmonics ground loop noise. Again, be sure to keep the circuit to just a local loop (at least the secondary, rectifiers, choke, and the first cap (and resistor and second cap).
But the power transformer is more expen$ive, and heavy; and so is the added choke more expen$ive and heavy. And, the choke needs to be far away from the output transformers, and oriented properly.
That is a good way to get the B+.
But just be sure to keep all of the doubler circuit in a local loop. Extending it out to
other areas of the amplifier, it will cause terrible hum/hum upper harmonics noise.
But it requires one more tran$former, the filament tran$former.
Choke input full wave with center tap, or with bridge, has the quietest hum/hum upper harmonics ground loop noise. Again, be sure to keep the circuit to just a local loop (at least the secondary, rectifiers, choke, and the first cap (and resistor and second cap).
But the power transformer is more expen$ive, and heavy; and so is the added choke more expen$ive and heavy. And, the choke needs to be far away from the output transformers, and oriented properly.
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