I have full wiring diagrams as well as a turret board layout for the "stereo SE kt88 build ... abdellah diyaudioprojects design" previously mentioned in this thread.
I too have mainly built guitar amps, so that's why I made a turret board for my amp.
PM me with your email and I'll send you the pdf package.
There's no shortage of help with this build either, plenty of people have built (and tweaked) this amp. Be warned though, it's not a powerful amp as it's an SE design. It does sound wonderful with a pair of high efficiency speakers though!
Glenn
EDIT: My page with this amp is here: http://webpages.charter.net/porkchop/tubeamp/KT88_SET_amp.html
I too have mainly built guitar amps, so that's why I made a turret board for my amp.
PM me with your email and I'll send you the pdf package.
There's no shortage of help with this build either, plenty of people have built (and tweaked) this amp. Be warned though, it's not a powerful amp as it's an SE design. It does sound wonderful with a pair of high efficiency speakers though!
Glenn
EDIT: My page with this amp is here: http://webpages.charter.net/porkchop/tubeamp/KT88_SET_amp.html
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probably not quite the amplifier you would want to build (SE 300B) - but this has a full wire layout.
Angela Model 91 Amplifier
Angela Model 91 Amplifier
The budget may be a problem. Typically you'll spend that much for the transformers alone, even cheap ones. Tubes, chassis, caps, etc., -- all extra.
I'm curious to see some suggestions that will maintain that budget.
..Todd
As it's been said before, it entirely depends on your goals, budget, skills, speakers and tons of other variables. I'll go out on a limb here and suggest 2 quite different things.
If you want something extremely affordable and basically fool-proof, check out tubedepot for the k-12 kits. I've never built one but I know of MANY folks that have, and I have heard a couple of them. Not bad for what it's worth.
Take it a step up, check out the project page on Angela audios website. The 'simple EL34' is just that. It is very simple if you can follow a schematic. The only thing I would insist on changing about it, if you want good bandwidth, is better and bigger OPT's. Other than that, follow step by step instructions, buy decent caps and resistors, and you have one hell of an amp for next to nothing.
If you want something extremely affordable and basically fool-proof, check out tubedepot for the k-12 kits. I've never built one but I know of MANY folks that have, and I have heard a couple of them. Not bad for what it's worth.
Take it a step up, check out the project page on Angela audios website. The 'simple EL34' is just that. It is very simple if you can follow a schematic. The only thing I would insist on changing about it, if you want good bandwidth, is better and bigger OPT's. Other than that, follow step by step instructions, buy decent caps and resistors, and you have one hell of an amp for next to nothing.
Thanks! That looks fantastic! What is the price range for that amp though? I don't really need the power of KT88s, which I believe is 19 watts in SE mode. What do you think? 5 watts per channel for 5.1 sound? 5 watts can get pretty damn loud.
Also, I have noticed that many HiFis use tube rectifiers. Why is this? I thought tube rectifiers were mainly used to get "sag" for guitar amps.
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Aren't 5 watt transformers significantly cheaper than 100 watt transformers? Couldn't I go with one of these:
EDCOR - GXSE5-600-5K
I don't really want a kit, I want to do turret layout or point to point.
I need help with a few things mainly:
1. Finding a nice stereo HiFi schematic. One that has been built many times, and has a good quality to price ratio. It looks like I have a few candidates here, thanks to everyone's suggestions. 🙂 I will review these over the next week or so, and post questions for each one.
2. Adapting this schematic for 5.1 surround sound. I also want to be able to switch between 5.1, 4.1, and 2.1, or possibly 5.1, 4.0, and 2.0. I want to be able to run my home theater through this amp, but also my record player. I don't know how the woofer or extra speakers will affect the sound quality when running the record player so I want those options. (Unless people here think 5.1 will be fine with the record player!)
3. Figuring out the power supply transformer requirements for the 5.1 amp. This is simply adding up the current requirements for the extra tubes, but I want to make sure I did it right.
4. Choosing good output transformers for the regular channels, and one for the bass channel.
5. Figuring out a good choice for the power tube for the bass channel.
I think I would like to go with 5 watts per channel, and perhaps 15-30 watts for the bass.
Thanks everyone! 😀
Even Edcor does not claim their GXS line to be "HiFi".
I think you said you could spend up to $300. OK for a 5 WPC amp realistically you'd spend $50 per transformer and you'll need three of them. If there is any part where you do NOT want to skimp, i's the output transformers. Edor makes good ones but the one you found is their bottm of the line. Move up untill you hit the $50 price point.
You don't need much else. Make a Chassis with a wood frame and a metal plate on top. Salvage the metal from a cookie sheet for the top plate. then all you need is two 6V6 and one 12ax7 tube and sockets and then resistors and caps.
If this is for an iPod you don't need RCA inputs (3.5mm TRS a better match) and you don't need volume control either. S you can comeout pretty cheap.
Heh I should have realized that you can't use a guitar output transformer for Hifi. Any good 5 watt output transformer recommendations? Do you think 5 WPC will be loud enough? (Living room listening) Running a record player or ipod into this. Also, what about a good output transformer for a woofer? And would you use a woofer with the ipod/record player, or just use the woofer for movies with 5.1?
Thanks!
I know you said you wanted to do a point to point or turret board, but I would seriously consider something like Tubelab's Simple SE amp as a first time hi fi project. Great sound, great documentation and great support. Simple SE My experience is that the most difficult thing to get right with a tube amp is layout. You might get it right first time if you have done plenty of research, but I must confess that my first amp was a disaster! I learned some good lessons, and I re-used the transformers in a later, more successful project. I would suggest getting Morgan Jones books, Valve Amplifiers (theory) and the companion book, Building Valve Amplifiers (practical building, layout and testing).
A 5.1 project is a little too ambitious to start with. Besides, with the weight of the power and output transformers, a 5.1 amp is impractical. I would suggest building a modest stereo amp first. If it works out, great, use it as your stereo front pair. You can then build a better stereo amp (even if it is the same design, your second attempt will be better as you apply the lessons learned on the first). The new one becomes the front, the first one becomes the rears etc... I would recommend a powered sub, or a solid state amp for the sub. The reason? Output transformers are expensive. The lower the frequency required, the bigger and more expensive the transformer required. Plate amps are cheap, and the 'chip amps' are easy to build.
What are you going to use to decode the 5.1 signal? Do you have a surround sound receiver with pre outs? If so, you can use its inbuilt amps while you build the external tube amps. To be honest, if you had this setup, I would build tube amps for the front pair, or front three, and leave the internal amps for the surround and the sub.
As for cost containment, the Edcor transformers are great value for money. You will need to choose one with an appropriate load for the tubes and speaker, however. The one you linked to had a 600 Ohm load for the speaker, you would want 4 or 8 Ohm and something like 3k to 6k reflected to the tube (depending on tube type etc). For the power transformer, Antek make torroidal power transformers that look reasonably priced, Edcor also make power transformers, Allied have transformers that look to be the same as Hammond.
Finally, I would say that if you want to do point to point wiring, you should take the time to learn what you are doing and why, otherwise, don't bother and get a well proven PC board design such as the Simple SE or simple PP.
Cheers,
Chris
A 5.1 project is a little too ambitious to start with. Besides, with the weight of the power and output transformers, a 5.1 amp is impractical. I would suggest building a modest stereo amp first. If it works out, great, use it as your stereo front pair. You can then build a better stereo amp (even if it is the same design, your second attempt will be better as you apply the lessons learned on the first). The new one becomes the front, the first one becomes the rears etc... I would recommend a powered sub, or a solid state amp for the sub. The reason? Output transformers are expensive. The lower the frequency required, the bigger and more expensive the transformer required. Plate amps are cheap, and the 'chip amps' are easy to build.
What are you going to use to decode the 5.1 signal? Do you have a surround sound receiver with pre outs? If so, you can use its inbuilt amps while you build the external tube amps. To be honest, if you had this setup, I would build tube amps for the front pair, or front three, and leave the internal amps for the surround and the sub.
As for cost containment, the Edcor transformers are great value for money. You will need to choose one with an appropriate load for the tubes and speaker, however. The one you linked to had a 600 Ohm load for the speaker, you would want 4 or 8 Ohm and something like 3k to 6k reflected to the tube (depending on tube type etc). For the power transformer, Antek make torroidal power transformers that look reasonably priced, Edcor also make power transformers, Allied have transformers that look to be the same as Hammond.
Finally, I would say that if you want to do point to point wiring, you should take the time to learn what you are doing and why, otherwise, don't bother and get a well proven PC board design such as the Simple SE or simple PP.
Cheers,
Chris
(Sub)woofers typically need a bit more power and therefore not very economical to combine with tube amps -- an active subwoofer could be a very good addition to a full-range speaker system, if needed ... many full-range speakers extend surprisingly low!
Best
Kenneth
I'm not getting 19 watts out of that amp, more like 5 from what others have measured, I personally think it's plenty loud.
Well, I wanted to keep it "all tube", but I currently have an LED bias setup on the driver 6N1P tube, sounds great!
EDIT: I don't think I ever added-up all the prices for a total. I built it over a period of 2 years, so I lost track.
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I have built several tube guitar amps from scratch, and besides the first one, they have turned out great. Did the layouts myself. I acknowledge that guitar amps are different from HiFi, but then again, aren't they fundamentally the same beast? I feel pretty confident that I can do the layouts myself. And if not, no big loss, as there are far fewer components in a HiFi than a high gain guitar amp. Or if someone would like to provide the layouts, I wouldn't turn them down, but this is the project I would like to build.
Heh, and you know I had the exact same thing happen when I built my first tube amp! I did the layout wrong, and ended up scrapping it. I managed to reuse most of the components though.
Great idea about building two separate amps! What about ground loops though? Maybe I'll do a 2.0 system to start, then build a separate 5.1 system after that, so I could combine them into 7.1 if desired.
You also make a great point about having the sub be powered. But then again....it is so very very tempting to build a 5.1, all tube. I realize the output transformers can get expensive, but that is the price we pay for HiFi. I'm willing to throw down an extra $100 on the bass channel output transformer.
I was thinking I would take the 5.1 outputs straight from a sound card.
What are your specific model recommendations for a 5 watt output transformer? Tube and transformer pairing? And do you think 5 watts would be enough per channel for a 5.1 home theater system, in a medium sized living room?
Thanks for the help!!
Is 5 watts enough? depends on your speaker efficiency and volume requirements. For me, the answer would be yes for the surrounds, but I have reasonably efficient speakers.
Yes, guitar amp layout is in theory similar. The differences that I see are that a guitar amp has much more gain, so is sensitive to low level interference, but generally hum and distortion are tolerated. The tagboard layout makes modification and repair easier, but is not the best solution for reduction of stray inductances and interference.
I love my tube amps, and I love building them, but I have an old Adcom 555 to drive my woofers. A dedicated tube sub driver just does not make sense to me. If you are willing to throw another $100 at a sub output transformer, you would get a much better system putting that money to improving the quality of the output transformer of the two front channels and going for a chip amp on the sub. For the same money you will have a much better system.
As for reasonable transformers, the Edcor open frame transformers are great value. I would go for at least the 15 watt versions though. I have two of these in a Tubelab Simple SE and they sound great, though they are only doing 80Hz up.
As for 5.1, don't do it all in one chassis, it will be unmanageable. For starters, have you investigated the power requirements for the power transformer? For single ended, you are probably out of 9 pin tube territory. 6V6 in ultralinear might get you close to 5 watts per channel, at about 35mA per tube, plus 5mA for each driver gets over 200mA. Use EL34, 6l6 or similar and you are looking at 60mA each for over 300mA. If you want to add the sub as well, you are looking at another 150mA on top. You can see your power transformer requirements are looking difficult to meet. Add to that the size and weight, the amp will be unmanageable.
As for ground loops, that is where the layout is important. If you cannot manage the ground loops within a 5.1, separate 2.0 amps are not going to be any different.
Cheers,
Chris
Yes, guitar amp layout is in theory similar. The differences that I see are that a guitar amp has much more gain, so is sensitive to low level interference, but generally hum and distortion are tolerated. The tagboard layout makes modification and repair easier, but is not the best solution for reduction of stray inductances and interference.
I love my tube amps, and I love building them, but I have an old Adcom 555 to drive my woofers. A dedicated tube sub driver just does not make sense to me. If you are willing to throw another $100 at a sub output transformer, you would get a much better system putting that money to improving the quality of the output transformer of the two front channels and going for a chip amp on the sub. For the same money you will have a much better system.
As for reasonable transformers, the Edcor open frame transformers are great value. I would go for at least the 15 watt versions though. I have two of these in a Tubelab Simple SE and they sound great, though they are only doing 80Hz up.
As for 5.1, don't do it all in one chassis, it will be unmanageable. For starters, have you investigated the power requirements for the power transformer? For single ended, you are probably out of 9 pin tube territory. 6V6 in ultralinear might get you close to 5 watts per channel, at about 35mA per tube, plus 5mA for each driver gets over 200mA. Use EL34, 6l6 or similar and you are looking at 60mA each for over 300mA. If you want to add the sub as well, you are looking at another 150mA on top. You can see your power transformer requirements are looking difficult to meet. Add to that the size and weight, the amp will be unmanageable.
As for ground loops, that is where the layout is important. If you cannot manage the ground loops within a 5.1, separate 2.0 amps are not going to be any different.
Cheers,
Chris
They are, as far as construction is concerned... Nothing wrong with building a hifi amp 'the guitar headamp way'! My recommendation would be to stick to the method you're most comfortable with. Downside is you won't find many ready-made turret board layouts in the diy hifi world. It's probably best for you to choose a solid circuit design and do the layout yourself.
Cheers
K
Can somebody please just answer the question? How to layout tube amp? I.e. Where to put components for lowest noise.
There are books written on the subject.
Building Valve Amplifiers, Second Edition: Morgan Jones: 9780080966380: Amazon.com: Books
and there's a great search feature on this forum, as well as this cool place.. Google
(sorry for the facetious answer, but this sort of thing is probably talked about daily on this forum)
Building Valve Amplifiers, Second Edition: Morgan Jones: 9780080966380: Amazon.com: Books
and there's a great search feature on this forum, as well as this cool place.. Google
(sorry for the facetious answer, but this sort of thing is probably talked about daily on this forum)
Take a look at some successful commercial tube amplifiers. You can try the Dynaco Stereo 70 first.
http://www.the-planet.org/dynaco/Amplifier/ST70.pdf
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