[Sarchi]

OK, the idea is to build an inexpensive, simple spud amp, just one tube per channel, single gain stage. Using 8 Ohm transformers and speaker taps. I don't want op amps or any silicon. I'm having great success running my low-z AT's off the speaker taps of my Sophia, I use very moderate gain on the volume pot and I use 10 Ohm 12w Mills resistors on the speaker taps, as per the headwize faq. I think it might be possible to build a decent "spud" under $200, but I've never done it. The Spud_kit at Hawthorne is appealing, but I'd like to keep the costs a lot lower if possible. My "inspiration" is the HA-02, though I realize I'm not going to achieve something that good on the cheap.

What suggestions could people point me to? Has anyone here done this?

 

[dsavitsk]

Quote:

Originally Posted by Sarchi /img/forum/go_quote.gif I think it might be possible to build a decent "spud" under $200, but I've never done it.

How about under $100: ecp.cc

At this point, I've done a bunch of versions of this, from the $100 version, to the ~$800 "More-pressivo" using custom wound Electra-Print parafeed transformers, Jupiter parafeed caps, etc. Just about any version is a good bang for the buck, but I'd say the Hammond 119DA as OPT is the best cheapo version. For tubes, 5687 or 6H30 for cheap, or E810F or D3a for a little more money, though lots of others will work, too. And, you can get in on my GB for CCS boards if you like. See post 11 and post 29 of this thread: diyAudio Forums - Another CCS for tubes/valves: PCBs

If you like single feed more than parafeed: ecp.cc Plus, I have a new version that is quite a step up from that as it removes all caps from the signal path except for a single 0.1uF bypass, and that uses a very unusual topology. I am still tinkering with it: HeadWize: DIY Workshop > New Project: S^3 (Shunt regulated, Series feed, Spud amplifier)

-d

 

[Sarchi]

Cool! I like your site, the capacitors page is what led me to try the Jupiters in my Sophia.

That new S^3 design looks very very interesting. I guess the less-presivo is more in my budget.

 

[fierce_freak]

Less-pressivo should be a good amp, especially for the cash. The S^3 looks very nice, too.

 

[Cata1yst]

Whats the difference between the millet hybird and the ones he linked?
does the hybird use Op amps somewhere that i havent seen like under the heatsinks and stuff?


sorry for the n00bie question and slight thread jacking

 

[FallenAngel]

Quote:

Originally Posted by Cata1yst /img/forum/go_quote.gif Whats the difference between the millet hybird and the ones he linked? does the hybird use Op amps somewhere that i havent seen like under the heatsinks and stuff? sorry for the n00bie question and slight thread jacking

Those are full blown tube amps running hundreds of volts, the millet is a hybrid (tube + solid state buffer) running < 30V.

 

[Cata1yst]

Ah thanks FallenAngel.....

 

[dsavitsk]

Quote:

Originally Posted by Cata1yst /img/forum/go_quote.gif Whats the difference between the millet hybird and the ones he linked?

The primary difference is that these amps use tubes for voltage and current, while the Millett uses a tube for voltage gain and a solid state circuit for current. The second important difference is that these are transformer coupled circuits, where as the Millett is RC coupled.