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April 19, 2019, 09:22:49 am

Author Topic: New to Hifi Tube Amps  (Read 137 times)

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Offline WhoWhat

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New to Hifi Tube Amps
« on: April 05, 2019, 12:42:06 pm »
Sorry if this isn't in the right forum, but I'm new to hifi amps.  I've built a couple of tube guitar amps and one very simple tube amp a few years ago. 

I'm looking to build a Stereomour II.  I've noticed it's 3.5w per channel.  All the hifi speakers recommend a minimum wattage of way above 3.5w. 

Please help me with this problem... Also, I'm looking to build a pair of speakers a the Chicago School of Woodworking.  Do I need to request specific drivers for this amp? 

Thank you

Offline Paul Joppa

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Re: New to Hifi Tube Amps
« Reply #1 on: April 05, 2019, 02:32:57 pm »
Yes, single-ended triode (SET) amps are very low power, and work best with high-efficiency speakers. In near-field listening, like computer speakers, you can get away with less efficiency.

Here's a link to a forum for high-efficiency speakers:

https://www.audioasylum.com/forums/hug/bbs.html

It's a fairly well-behaved forum, with only occasional rowdiness  ... :^)  Just be aware that the community is about equal parts SET users and those who like it REALLY LOUD. But both types are usually glad to help a newbie.

Speakers are usually rated for sensitivity, in dB at 1.0 meter distance with 2.83 volts input (that's 1 watt if the speaker is 8 ohms, 2 watts if it's 4 ohms). My rule of thumb is that a 4-watt amp like Stereomour will be loud enough for most audiophiles, most of the time, if the speaker sensitivity is 96dB. This will be significantly affected by your room size, taste in music, etc., so don't obsess over it too much!
Paul Joppa

Offline oguinn

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Re: New to Hifi Tube Amps
« Reply #2 on: April 05, 2019, 02:51:23 pm »
I am currently using a SEX (2 watts per channel) paired with a Smash pre and it drove a set of pretty inefficient Overnight Sensations plenty loud enough. I have them in a small office, not a huge room, and my definition of loud enough might differ from yours.
Jameson O’Guinn

Offline Paul Birkeland

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Re: New to Hifi Tube Amps
« Reply #3 on: April 05, 2019, 03:09:06 pm »
  All the hifi speakers recommend a minimum wattage of way above 3.5w. 
At some point in history, speaker power handling ratings went kinda nuts.  There are speakers out there with very high sensitivity that claim to be able to handle hundreds of watts.  In my opinion, the power handling specification these days is pretty meaningless, and it's mostly meant to avoid the problem of people thinking their amplifier is too powerful for their speakers. 

Also, I'm looking to build a pair of speakers a the Chicago School of Woodworking.  Do I need to request specific drivers for this amp? 
There are lots of designs out there for the Fostex full range drivers, and the larger ones are pretty efficient.  You could also look for a really, really ratty pair of ancient Klipsch speakers and just build new cabinets for them. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man