SET 45 Amp Driving Dynamic Speakers

I have owned many 45 SET amps as well as loads of other SET to get the best out of 45 I have had to biamp even on horns the 45 SET doesn't drive woofers well but is amazing  on horns. I have had some luck using with fullrange BLH with 45 SET. But I do see many SETing themselves up for failure by not matching loudspeaker to amp. 

Atmasphere raises a valid point however context is essential. How loud is loud enough ? Clearly there’s no single right answer as limits are individually set by a listener. We all determine our respective comfort zones of SPL(sound pressure level). Tommie’s Audio Note speakers are 95-97 db sensitivity. If he listens at say an average SPL 75-80 db he’s using mini watt power i.e. small fractions of 1 watt. Depending on room size and music genre he is likely as happily content as he describes. The vast majority of his enjoyable listening could be occurring in the mini watt power region. numerous variables must be considered. "Just right" volume level for one person may be too soft or too loud for another.


Tommie what SPL do you typically listen at in your home? Not everyone seeks 100-110 db peaks.it all depends on what makes you satisfied.

A type 45 can make about a 1 watt or slightly less running single ended.

To really appreciate what they can do (which is to say, they usually sound better than a 2A3 or 300b amplifier) you actually do need some efficiency and the only way to get the efficiency you need is with a horn system unless you are in a really small room, perhaps a closet.

If you drive the amp too hard, the odd-ordered harmonics that the ear uses to gauge sound pressure will appear. This causes the amplifier to sound 'dynamic'. In the initial opening post, we can see that this is happening. Its important to understand that this 'dynamic' quality is really the result of distortion appearing on the transients where most of the power requirements exist. Its a physiological interaction with how we perceive sound.

The problem is, once you know this, you can perceive it as distortion, not just 'dynamics' (in about 90% of audiophile conversations, the word 'dynamics' can be safely substituted with the word 'distortion' without changing the meaning of the conversation). So if you have read this far, I may have wrecked it for you.

You can prove this easily enough by obtaining a sound pressure level meter. They are available as apps for smartphones. You will see that its really not playing that loud- it just sounds like it due to distortion.

Excellent, informative posts from my fuse-loving friends above.  ;-)  I have two Dennis Had amps, an SET and and SEP amp, one based on EL84 and the other on nearly any power tube you can get into the sockets, from EL34 to KT150's.  16 wpc and 6 wpc, respectively.  The smaller amp is sublime mated with the Spatial Audio Holograms and the bigger one drives my Zensor 3 speakers in the bedroom, both with all the power I need.  They both have a warm euphonic sound.  Rolling tubes is joy with these amps and some of the new tubes are as good as the pricey NOS tubes I have heard, particularly the Gold Lions.   

The Yamamoto A-08S is on my list, if I come into some unexpected cash. I'd run it into my ANs (92 db?) full range, just like I'm doing now. I'm sure it will have enough "slam" for when I play The Killers. 90 db is LOUD!

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!

Great comments,
Could not agree more. Happy listening, best, Rob

tommylion:
Of course you are correct that SET amps can provide an exquisite and special listening experience. The key is your wise words "carefully chosen speakers". Your Audio Note speakers are specifically designed for your type of amplifier and listening. The AN web site basically states to get the best results -use a SET amp.

I have a horn system and also a dynamic driver Teresonic system.  The horns are driven by the 300 B SET amp and the Teresonic by the 45 Tube SET amp. I think both provide a special intimate and moving musical experience.

A big problem I see repeatedly is speakers being sold that are not efficient but somehow are so special in some sort of novel design that they will perform to their optimum with a SET amp. Buyers then give the SET amp a bad rap for lacking dynamics or bass when the seller's hype exceeds the laws of physics.

I hope to try the Emission Plate mesh tubes some day. From what I have read in the just right system they add a special touch. Congratulations on having that system.

David Pritchard

Hello,
I happen to agree with your comments. This is why I often state that you actually have to listen to a component/system to get to the truth. Otherwise it’s far too easy for preformed opinion to be presented as fact. I have 94 dB sensitivity/ 14 ohms speakers that I originally drove with 100 watt PP tube amplifiers(60 watt in triode mode) and this match was exceptionally good sounding. 

Strong curiosity led me to purchase an 8 watt SET amplifier (mono blocks) using 300b tubes seven years ago. For my particular listening needs and taste the 8 watt SET improved my system’s presentation and moved it to a higher level. In other words I went from legitimately "very good " to superb . It all depends on what musical and sonic parameters are most important for a individual listener. I’m glad that I took the chance to try the lower power amplifiers. The crucial key is defining what type of sound you are looking to achieve.