# Tube amp kit for Christmas present?

#### kyroguy

Joined May 12, 2010
77
I am thinking of getting a tube amp (kit preferably) for a relative for Christmas. I have general knowledge of electronics, but have no experience with tubes or tube amps. I am thinking something relatively small, maybe a headphone amp?

Any suggestions would be appreciated. I would be very happy if I could find a kit that he could actually solder together with a board and everything. Second best would be schematics with a parts list so that I can get everything ahead of time. Worst case, a small tube amp that is preassembled but open enough that he can see it all inside.

Any suggestions would be greatly appreciated!

#### bountyhunter

Joined Sep 7, 2009
2,512
Ask him if it's what he wants. IMHO, a solid state amp will be more practical. Tube amps typically have some hum or noise a good SS amp won't have and you will hear it in phones.

Not starting a war, I used a tube amp for a long time, but the soft warm glow of the tubes is their main advantage. That and status....

Tube amps (even kits) are pricey by comparison.

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#### SgtWookie

Joined Jul 17, 2007
22,210
If you consider kits, keep in mind that building a tube power supply will not be cheap. Transformers with HV secondaries suitable for use in tube amps are pretty rare and therefore expensive nowadays.

#### kyroguy

Joined May 12, 2010
77
I completely understand your response and don't take it as hostile at all. I don't know why he has a fascination with tubes but he has been practically begging me to bid on some broken tube stuff on eBay for him. This is how I know he wants one. He would probably kill for a full size amp, but they are super expensive as you mentioned. This is what turned me to the headphone size amp.

He has pretty extensive experience working on ss amps. He lives in a small town and already at 16 years old he is known around town as the guy to bring broken electronics to to get them fixed. He has fixed TVs, stereos, computers, etc. He has also gotten several ss amps that were broken for free and fixed them, so he already has all of that he needs. He's probably the only kid in town with a big screen TV in his room. He got it free as well and fixed it!

I guess he just feels like tubes have some mystical power since he has never really played with them. I fully expect the tube amp to be a disappointment, but he can be the final judge of that.

I have browsed some kits and have seen stuff in the sub $100 range, which is hopefully where I can stay. Thanks for your input, I look forward to hearing more opinions on this. #### Audioguru Joined Dec 20, 2007 11,249 Tubes wear out. He will be dissappointed when a tube wears out and he can't find a replacement or can't afford the inflated price for a used Russian one. In 1962 I made a kit tube amplifier because a good transistor one was not available yet. The tubes needed to be replaced every 3 months to keep the distortion less than a horrible 10%. I sold it a couple of years later and bought a solid state stereo receiver that still works perfectly today with no audible distortion. #### bountyhunter Joined Sep 7, 2009 2,512 Tubes wear out. True.... but the odd thing is, I obtained an repaired a Sterophonic 3030 Bell tube preamp-amp in 1968 and used it until about 1985 and never lost a tube... and I bought it well used and used the hell out of it. The 25" color Heathkit TV I still have (laughing at me in the corner) ran from 1974 to about 2005 before I gave up repairing the solid-state flyback converter assembly..... the picture tube was still good. go figure Thread Starter #### kyroguy Joined May 12, 2010 77 Here is a kit that I am leaning towards after an initial look. http://diyaudioprojects.com/Solid/12AU7-IRF510-LM317-Headamp/ It doesn't seem like it is too complicated. It has complete schematics and parts list, and it comes in way under the$100 mark. It also seems to have good support through a dedicated forum thread in case we get stuck with the build. There is tons of info to sift through, including 80 pages of forums posts but maybe you could briefly browse it and see if you catch any obvious problems.

They aren't selling it in kit form. I would have to source the parts myself, which isn't a problem. Here is the mouser cart I put together for it.

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=e1d7fc1b0d

The only other parts are the tube/socket, power (battery or supply) and enclosure. The tube/socket came in at \$15 and up. I have tons of power bricks sitting around and we could source an enclosure depending on the final size of the board.

So what do you think? I am certainly open to better ideas as well!

#### Audioguru

Joined Dec 20, 2007
11,249
Some very expensive audio amplifiers today have a glowing vacuum tube or two on top.
They are for show and are not part of the inexpensive solid state circuit.

#### JMac3108

Joined Aug 16, 2010
348
Tubes such as the 12AU7 shown, and other similar ones such as 12AX7 are actually quite available now and ar not that expensive. These are commonly used as preamp tubes in guitar amps. Ther are still many vintage tube guitar amps as well as new ones out there.

One thing to consider is that most tube amps use high voltages and are not generally isolated until the final output. This means you can get seriously shocked working on them. --OOPs, I took another look at the circut for the headphone amp and realized it only uses 12V for the tube! --

#### Jotto

Joined Apr 1, 2011
151
Most every tube made is being reproduced. Some in the Russia and China.

I use KT88 tubes in my unit. You will not have a richer sound then you get with tubes. You don't need a lot of power, some units are very low.

Most older units also had the tubes exposed for keeping the temp down Mine were made in the 60's and had a cage on top for the tubes. I have not seen very many units that still have the cage.

Mine is HK Citation I preamp, 2 Citation II amps. I can have the units set in either stereo or mono block. In stereo its 60 watts per channel, mono is 120 watts. I modified the preamp to handle digital input so I can use a DVD player for music.

The headset units are very nice also, hum and distortion isn't a problem in the units I have seen. As the saying goes, you get what you pay for.