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SET 45 Amp Driving Dynamic Speakers

I have an Antique Sound Labs Tulip SET amp running Emission Labs mesh plate 45s, driving Audio Note AN E speakers. It will play WAY louder than I want to listen, and the dynamics are amazing with all types of music.

Why do I keep reading that 45s (and other low power triodes) are only appropriate for horns, or other super efficient speakers? I think a real disservice has been done to the audiophile community by the propagation of this idea. IMO, anyone who prefers to listen to music at sane levels can enjoy the many benefits of a low power SET amp with carefully chosen dynamic speakers.

Anyone else feel this way/have similar experience?
tommylion

Showing 5 responses by lewinskih01

lewinskih01
793 posts
 
Ralph,

I thought 45s made 2W and one should run them at under 1W draw to keep distortion from growing much.

Is this what you mean by 0.75W?

lewinskih01
793 posts
 
Indeed, high efficiency and high impedance speakers are common factors when you read/hear someone is happy with a SET amp. Another factor is the SET should be driven "well below" its rated power, which is of course undefined how low is low enough.

I'm in the process of building an active system with SETs for treble and midrange and class-D for midbass and subwoofers. It's said power required below and above 350Hz is about the same, so by crossing around there (or higher) you relieve the SET from carrying half the load. If you further divide the upper range into two, then each amp will carry 1/4th of the load.

I have my eyes on Yamamoto's A-08S (45 SET), and while the speaker driver options aren't super wide, there seems to be enough. I guess demand pulls for drivers where high efficiency and impedance aren't as big a deal, the manufacturers follow suit. It is being a fun journey!
lewinskih01
793 posts
 
Hello Ralph (Atmasphere).

I've seen your comments before and I am keeping them in mind as I design/assemble my new system, a 4-way active. If using a 45 amp to only reproduce 350 to 2000Hz on a 100 dB/W driver in a 25m2 room and if average listening level is 85-90 dB SPL, would a 45 suffice or be driven to the point where 5th order harmonics become an issue?

Thank you!
lewinskih01
793 posts
 

Hello Al.

Thanks for the excellent and thoughtful reply. I've gone through it several times in the last couple of days.

You made it very clear so I can work through the tradeoffs. Maybe running the amp up to 50% si not as offensive? Something to try and learn.

I think most of my music is going to be rather compressed. Of course I have some good recordings, including Telarc's Firebird you mentioned, but the majority of my listening is going to happen with lesser quality recordings. Let alone having 3 kids into teenagehood and wanting to share some listening time with them, with their music ;-)

FWIW, I'm working on the midrange driver. It's a horn-loaded cone, so efficiency is yet another tradeoff in the design. I believe 100dB/W is about a floor, and probably a cieling around 106dB/W. Hopefully I can get it to 103-104dB/W and then things start to look significantly better. Or I'll have to settle for a 2A3 or higher power amp.


Glad to see a healthy thread develop on SETs. I'm hoping that eventually more people will be open to try what well-implemented DSP can do for a system (emphasis on "well-implemented"), just like Charles was open to experience well-implemented digital. Not saying it will be best for everybody, but I find it a pity people follow so many preconceived notions in audio and preclude themselves from trying new things. OK, time to get off my soap box :-)

lewinskih01
793 posts
 
Hi jsman.

I'm interested in learning more about your midrange horn. Is it circular? What are your xo points and what is the horn cutoff frequency? I'm also exploring tractrix midrange horns. Right now with a suitable cone driver but also considering compression drivers.

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