Tube into solid-state

[whateverman]

i have a question. i want to build my own amplifier to get started in the DIY stuff. i'm going to be earning my degree in electronic engineering next year and i think a fun hobby would be to design and build my own amplifiers (i already have some really great ideas), so a DIY kit right now would be a pretty good start.

i want to start with tube amps, mainly because i have never heard them and i want to see what the sound is really like. so i've almost decided on buying the Foreplay III line stage amp kit from bottlehead (probly with the extra add-ons too).

now, since the emotiva bpa-1 is on sale for 150, i really want to buy it. would you say it is a good idea (sound-wise) to connect my source (cd player or computer sound card) to the line stage tube amp, and then run my tube amp into the emotiva.. which would then output to two speakers in stereo? would i get enough of a sound quality increase to justify doing this or is it just a dumb idea?

 

[fmw]

I'm not sure I would call it an increase in sound quality. Tubes amps and preamps (been there, done that) have frequency response curves that are less linear than solid state amps. It is the nature of hot vacuum tubes. In other words, the tube amp is likely to act as a tone control enhancing the mid range, cutting the bass a smidge and cutting the high frequencies audibly. If you like the sound, then that's fine but I think a tone control would be easier and cheaper to build. But "filtering" audio through a tube amp or preamp is a change in sound quality, not necessarily an improvement.

Building kits is great fun. I've built all kinds of them, the most complex being an old Heathkit ham radio receiver. I can understand why you want to do it. So do it.

 

[whateverman]

Tubes amps and preamps (been there, done that) have frequency response curves that are less linear than solid state amps. It is the nature of hot vacuum tubes. In other words, the tube amp is likely to act as a tone control enhancing the mid range, cutting the bass a smidge and cutting the high frequencies audibly.

hmm.. is it a characteristic of all vacuum tubes to enhance the midrange and cut the bass/treble? if not, do you think i could modfiy the circuit so instead of enhancing the midrange, i could enhance the lower frequencies (such as adding different types of filters).. or maybe have three tube amps in parallel, one enhancing the midrange, one for the bass, one for the treble? and then have a final amp at the end combining all of them?

lol my mind just goes crazy thinking of all this stuff, i'm like a mad engineering scientist. i can't wait until i have enough money so i can play around with all these ideas

 

[fmw]

Not universal, of course, but it is common among less expensive units. What is common is a lower level of linearity of frequency response. My last tube amp was fairly accurate - accurate enough that it sounded about like a good solid state amp. But it cost over $5K. There was a time when I had more money than sense.