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Bronze Member Username: GuillemotLansing, Mi Post Number: 29 Registered: Nov-07 | Happy New Year all! I've been enjoying my new stereo for the last month. This has led me to begin thinking about the next thing to obsess over. I'm intrigued by tube amps. There is a mystique that surrounds them, - perhaps perpetuated by the eccentric do-it-yourself folks who enjoy them. They are described in poetic terms that might be reserved for cigars, good wine, or other vices. So I've begun reading on home-building tube amps as they seem fairly straight forward to construct for the technically inclined. I'm not running out to radio shack yet - just reading. Most of these amps, both home or commercially built, are relatively low powered compared to anything I'd ever heard of - like 1-3W. A small proportion of them get up over 10W, and the very long tail of the distribution leads to one (expensive) kit for a 100W stereo amp. So what's the deal? Why so low power other than being maybe safer to work with and probably less expensive to build. I have a pair of B&W 602 S3s with 90db sensitivity that want 25W -- 120W into 8Ω. This seems beyond the reach of 95% of DIY tube projects. What would it take to power them with a home built amp? Just for fun, remember!! Happy Holidays, Jeff |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 11918 Registered: May-04 | . The B&W's are not really a good choice for most tube amps and certainly not for the typical DIY tube amp. The current B&W speaker line up requires a fair amount of current delivery in comparison with the speakers normally paired with tube amplifiers. If you want to stay with your present speakers, I would suggest you stay with solid state amplifiers with high current capability. The very low powered DIY's you're seeing are SET's (single ended triodes) which operate somewhat differently that the typical push-pull configuration most of us have become used to buying without thinking. Triodes and single ended operation are the original power amplifiers in audio. SET's offer certain advantages and some definite disadvantages. A search engine on SET's will provide more information. In the meantime, I would suggest you start with this thread; https://www.ecoustics.com/electronics/forum/home-audio/119397.html When you're finished with that, come back and ask more questions. . |
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New member Username: Oldschool2424Edmonton, Alberta Canada Post Number: 6 Registered: Dec-07 | Tube amps are making a comeback and are in production from MacIntosh, one of the best. http://www.stereophile.com/tubepoweramps/429/ Here is more information on them. There you will find all the current you need to drive those amp hogs of yours. |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 11927 Registered: May-04 | . Current is only one issue which needs to be addressed when pairing a tube based amplifier with any speaker. If the speakers are fairly to highly reactive - broad impedance swings and highly capacitive or inductive phase angles - they are probably not the best choice for a tube amplifier. Due to the high output impedance of vacuum tubes the final output impedance of any tube amplifier will be reasonably high when compared against a solid state amplifier of even mediocre quality. This high output impedance of the amplifier will interact with the impedance swings of the speaker load and the result will be irregular frequency response as dictated by Ohm's Law. Depending on the amplifier the output impedance might be as high as 2 Ohms or more which would easily translate into a 1.5-2.0 dB shift in frequency response across the amplifier's bandwidth. It's simply a better idea to buy speakers which suit a tube amplifier. . |
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Gold Member Username: NuckPost Number: 9530 Registered: Dec-04 | I like the small tube amp I have (asian) with Sovtek tubes and the RFSD speaker arrangement. The single driver is very predictable, without an XO. Larger tube amps, in AB like Jan's Mac setup can power tough loads, but get a little bit wasted that way. Tube amps change with the tubes. You can get into tube rolling, but buyere bware. Getting the right amp the first time is always best(after quite a few). Welcome, MM. |