Tube Amp Kit Suggestions

[baltimoreblues]

I am thinking of buying a cheap kit to start with for practice on leaning more about how these what I consider wonderful sounding amps are built. Any suggestions on cheap beginner kits would be much appreciated. I can read all day but need to solder and conect to learn, at least that is my therory.
thanks in advance JOHN

 

[planet10]

The K12-M is a popular low budget entry level kit.

http://diyaudioprojects.com/Tubes/K-12M/K-12M.htm

dave

 

[gmilitano]

The K-12 kits are ideal for a beginner and deliver good performance for the cost.

Here are a number of K-12 Tube Amplifier Kits. Keep in mind that the kit does not come with an enclosure.

Good luck.

 

[tinitus]

This one looks nice too, but only max 4watt...I dont think it has been around long enough to have any rewievs here, assembled and tested board

http://www.engineeringvista.com/audio/AudioKits/Model-1/pictures_m1.htm

Maybe a bit more difficult, cant say but I think it looks nice, complete kit

http://gabevee.tripod.com/cgv0606.html

And the obvious choice, but no kit

http://www.tubelab.com/SimpleSE.htm

And this sweet thing, seems to be a complete kit

http://www.hawthorneaudio.com/spud_kit.htm

http://pages.prodigy.net/jimmcshane/citpage.htm#parts.htm
http://pages.prodigy.net/jimmcshane/elcheapo.htm

 

[gofar99]

Hi John, There is another similar thread on this subject in this section. The K-12 is a good performer for the price. As a first time kit it is pretty easy to build a working amp. As was noted, it is without a case and depending on your situation this is a potentially serious problem. Hot tubes and exposed voltages are not kid or spouse friendly (could be a problem for house pets too). Welcome to the tube family.
Bruce

 

[baltimoreblues]

Amps

Thanks Bruce and everyone for the leads on some projects to look into. I have a few tube amps that I am currently using, and some that need work. Have a pair of Bogen 110's that are hooked to a pair of KLHs that sound so sweet it is unreal.
I have a larger setup consisting of pair of Dynaco MK IVs driving Bozak symps B-4000s. And I just love lps, the blues grew up with the blues playin listening just enjoyin.
BUT.... i have no working knowledge of amps dont do my own repairs and have yet to find a decent small scale repair person who I can use, so I feel it is time to learn. Start slow see how it goes. Anyone want to kick around some ideas feel free, I cant use private messaging yet because I am new to group so cant get into any detail questions yet.
Enjoy, JOHN

 

[gofar99]

Hi John, email me at gofar99@hotmail.com if you desire. I may have a few ideas for you.

 

[ambience exists]

HELLO,

I am planning on making the now almost cliche S-5 kits!

Which company do you think would be the best bet, "tubeaudio.com" or Antique Electric Supply?

((AE))

 

[gofar99]

Hi, Either source is fine. I personally like dealing with AES. Not always the lowest price, but extremely responsive to my needs. Good luck with your build. There are several mods possible for this amp.

Good listening
Bruce

 

[audiowize]

For a beginner, a point-to-point kit will generally teach you a lot more, while a board will be a quicker build, but you won't really learn anything about layout, grounding, etc.

 

[ambience exists]

Does anyone think that I would have grounding/interference issues with a hardwood chassis for the k-12?

It sure would look nice...

 

[jduffy]

The Bottlehead SEX amp is a good P2P kit but might be too expensive for you. If you want to use speakers with it as it is a headphone amp, they would need to be very efficient.

Good luck with your build.

 

[gofar99]

Hi All, I routinely use wood and plexiglas for chassis and have no problems. I generally use a heavy gage central ground buss wire to avoid problems. I keep connections to it as short and direct as possible. I have tried two methods of connecting the buss. One at the input side of the amp and alternatively at the the main power supply ground. Both have worked well for me. None of my current amps including the present P-P KT77, has over 1 millivolt of hum or noise at the speaker outputs.

I have discovered a problem with non-metal chassis in the past. You can not place them near something that generates EMI. I had one on a top shelf (near the ceiling) and it picked up the noise and hum from the heat tapes ( I have radiant heat). Also they will pick up TV generated interference if too close to a TV.

I find it a bigger problem with ground loops in metal chassis. Even with care they can crop up. I isolate my audio circuity from the case if it is metal for just such a reason.

 

[ambience exists]

Thanks, I have heard about hum issues with the s-5 gear and wouldn't want to aggrevate the problem!

((AE))

 

[gofar99]

Hi, My K-12 is in a metal case (actually one from S-5). I did have some hum issues at first with it, but after isolating everything but the power transformer from the case, they went away. Since then all my amps are in wood cases. Plus I personally think that wood visually matches the warm sound of the amps.

If you run out of ideas on where to get chassis and such, check out the kitchen sections of most big department stores. I regularly use "kitchen" organizers and have some copper rectangular baskets that with a bit of trimming make great tube covers. I tried to paste an image of the early chassis of my newest project, but it doesn't seem to load properly. You can see it on another forum (diyaudioprojects.com) if you want.

Good luck with your project

 

[bayermar]

Hi all,

IMHO the hum issues are not caused primarily by lack of shielding.
The main source is the PSU, which needs to be modified. Shottky diodes and a choke or a CRC network will do the trick. I think most of the hum is caused by ripple current. Keep in mind that the PP output stage is not completely symmetrical since the tubes share a common cathode resistor and there is no way to set the idle current through each tube individually. Elevating the heater ground may help, too. I got my AES kit very quiet this way (there is a very low hum present when pushing your ear right into the speaker).
I do not see a problem with a hardwood case, since my modified kit was already very quiet without any case at all.
Although there is definitely a lot of room for improvement those kits already sound very nice in the stock configuration. And once its working it is a lot of fun to tweak.
Even if I ended up spending quite some money for modifications - the learning experience was definitely worth it.

Martin

 

[ambience exists]

Just got the kit...

I was wondering, how do I rig a power on LED to the circuit?

That would be pretty useful

 

[nigelwright7557]

Hi all,

IMHO the hum issues are not caused primarily by lack of shielding.
The main source is the PSU, which needs to be modified. Shottky diodes and a choke or a CRC network will do the trick. I think most of the hum is caused by ripple current. Keep in mind that the PP output stage is not completely symmetrical since the tubes share a common cathode resistor and there is no way to set the idle current through each tube individually. Elevating the heater ground may help, too. I got my AES kit very quiet this way (there is a very low hum present when pushing your ear right into the speaker).
I do not see a problem with a hardwood case, since my modified kit was already very quiet without any case at all.
Although there is definitely a lot of room for improvement those kits already sound very nice in the stock configuration. And once its working it is a lot of fun to tweak.
Even if I ended up spending quite some money for modifications - the learning experience was definitely worth it.

Martin

I always us PI filters in my valve pre amps.

One unexpected source of HF noise in my tweeters was the 1N5408 switching pulse. I had to put a 100nf across the transformer to kill this.

 

[starro]

Thanks everyone. The K-12 looks like a great option, but I can't seem to find the kit for sale anywhere. TubeDepot and S-5 Electronics doesn't seem to make them anymore. Any suggestions as to where to get a kit?

 

[tinitus]

"Simple-SE" from Tubelab.com is probably the best, but only prints and no components

The DECWARE kit would be next on MY list
The fact that you also need speakers could make the low watt a non-issue