SET 45 Amp Driving Dynamic Speakers

When I checked my levels in the past, I didn't get much above 90 db on peaks. That was setting it as loud as I would ever want to listen. Most of the time, it was lower than that. 100 db peaks must be painful, not to mention the potential for hearing damage.

I'll have to pull out my db meter and check again.

I use an autoformer passive preamp. My understanding is that, in contrast to a resistive volume control, the output impedance gets lower as you lower the setting. This results in better sound at lower volumes, which corresponds with my experience.

Hello Tommie,
Given your preferred listening levels and comfort zone I can understand why you are satisfied with your 45 SET and Audio Note speaker match, Congratulations. As I mentioned earlier not everyone desires or wants to listen that loudly (100db or greater peaks). This is strictly an individual preference issue. If you have good hearing ability (and want to preserve it) your limits of listening volume would satisfy many other listeners as well. To each their own as the saying goes. Tommie 100 db SPL is loud (though not necessarily uncomfortable). I’ve measured this level at live venues with unamplified instruments and even under these natural conditions (no electronic distortions via PA system) it’s definitely perceived as loud. I’m assuming that a listener is without some degree of hearing loss. Otherwise perception of loudness would certainly vary.
Charles,

Just just to make things clear, I'm not saying one can pair 45s (or other low power SETs) with ANY quality dynamic speakers, and expect good results. However, higher efficiency dynamics, that are known to present a benign load (like the Audio Notes), are a very viable option. Especially if you prefer to listen at low to moderate levels.

When I checked my levels in the past, I didn't get much above 90 db on peaks. That was setting it as loud as I would ever want to listen. Most of the time, it was lower than that. 100 db peaks must be painful, not to mention the potential for hearing damage.

If 100 db peaks are painful, either you already have some sort of hearing damage or the amplifier is making a lot of distortion. The measure of any good system is the quality wherein it is not easy to figure out how loud its playing without instruments (sound level meter) or trying to talk to someone beside you and be heard. IOW 100 db peaks should be effortless and relaxed!! Usually when a system sounds like it is loud or verging on painful that is a sure indication that distortion is playing a role.

The usual solution is more power so that the amp will not make distortion.

In Tommy's case, with only about 0.75 watts to 1 watt available, the maximum power before higher ordered harmonics appear is likely about 0.15 watts to 0.20 watts. The sound pressure with the Audio Notes at 1 meter is thus about 90 db (less at greater distances) before harshness sets in. From his comments it appears to me that he is routinely pushing the amp too hard- he is likely further from the speakers than just 1 meter.

Unless he's listening in a very lively environment or in a very small room, the simple fact is that a more efficient speaker will bring out a lot more of the magic that 45s have in spades (I have type 45 amps BTW; my speakers are 98 db and the amps fall flat on their face because they simply don't make the power. My room is 17' x21'.). This is one of those situations where context is everything as Charlesdad points out. For example, as a desktop setup this would be pretty sweet. But for serious home listening I'd want a speaker that was more like 107 db, such as the Hartsfield or something like that.

The magic of SETs comes from the fact that as power is reduced, so is distortion, down to the point where it becomes unmeasurable. When you are running distortion this low, the result is that more detail is revealed as it is not obscured by the distortion due to the human ear's masking rule. A type 45 amp no if ands or buts has wider bandwidth than higher powered SETs- that is why it sounds better. If you really want to hear what that is all about a high efficiency speaker is mandatory.

My approach is I want to be able to enjoy listening at any practical volume needed. The only way to accomplish this is to avoid clipping and distortion.

One might be satisfied with lower volumes only but if speaker amp integration is not done well one may practically have no other choice.

Also distortion usually sets in at subtle levels that may not be clearly audible well before one becomes aware of a problem.

One may certainly choose to not care about these things but they are real issues to consider and understand for best results in most any case IMHO.