• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Tube amp recommedations

I'm looking to build a stereo integrated tube amp and am looking for suggestions as to which one to build. I'm looking to spend a few hundred (up to around $300). I'll be using it in a small room, and I don't listen to music very loud, so I don't need a huge amount power. I'm more concerned with aspects such as soundstage and dynamic range. I welcome any recommendations or opinions.

speaking of the Dynaco 70

Food for thought. The Dynaco ST 70 amp is a sweetheart once upgraded. Of course the amp I am talkin of is the older ones with the cloth transformer output wires. Right off the old dusty shelf typically this amp needs work. But man oh man, the output transformers on this baby make it hard to beat. There are tons of web sites deticated to this little gem and there are plenty of upgrade kits available for it also. This is a real fun builder of an amp and one best get em while they are still available. They sell fast on e bay and fetch in a range of 350.00 dollars for bone stock units.
Amp recommendation

If you think you can build a kit a good site to check out is http://gabevee.tripod.com/ Gabe has a kit for a stereo SE 6L6 amp. Ask him about adding volume controls as that is real easy. Then you don't need a preamp unless you are using a phono. CD players and tuners have enough power that you can patch directly to an amp. Using speakers that are efficiant enough the mids and highs of a SE tube amp are extremely hard to beat and that is where most of what you hear is. If you are in a smaller room you won't have enough space for the long sound waves needed for deep bass anyway. A good ready to play Dyna ST 70 will run you $350 or more and you will still need to work on it. If you are going to go for an older PP tube set up I highly recommend investing in a Fisher 400 reciever that has been gone through. The price will around the same as the Dyna but I and many other tube rollers prefere the Fisher output transformers over the Dynas or Scotts, and the Fisher 400 has the advantage of being integrated and has a very high quality tuner in it. There is also a center channel output that you can slave a subwoofer to if desired. None of the vintage PP gear will give you the soundstage and dynamics of a SE amp though. You will lose some power and a bit of bass but what you will get will give you goose bumps and possibly make your toes curl a bit.
Re: Amp recommendation

Thatch_Ear said:
... If you are in a smaller room you won't have enough space for the long sound waves needed for deep bass anyway. ...

what? you've got to be kidding.

I appreciate your links and will follow them, but c'mon. are you sure about that?

I submit that bass will develop in small spaces BETTER than in 'normal' or large ones. The walls result in boundry gain/room gain/cabin gain, etc.

Ever hear a 18hz note at 135db? i have. It was in a listening space with under 150 cubic feet.

The sound wave for an 18 Hz note is 62.68 feet long. Easy to figure out...speed of sound is 344 meters per second divide that by cycles per second or Hz and multiply by 3.28 feet per meter. Building transmission line speakers you use a quarter wave to tune the box to the fs of the driver. 18 Hz would require a 15.67 foot long tube. If you are inside 150 cubic feet and getting 18 Hz you are are basically inside an acoustic suspension speaker box absorbing the standing waves. I am not knocking it, just passing along what someone taught me about small room acoustics. Have fun no matter which way you go!

David and Grey are correct. What we are hearing when we listen to music(frequency) is the difference in wavelength and their effect on air molecules. High frequencies have a very short wavelength. This is why lower frequencies require more power than mids or highs. If you want to see how these effect the air molecules you can watch it in slow motion by throwing rocks in a pond. Don't skip them just drop them. Use smaller rocks for high freq. and larger ones for low freq. . Notice the difference in the ripple size and length. Sounds weird I know but all a speaker does is vibrate air molecules much in the same way a rock causes a wave.:rolleyes: