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SET 45 and their (real) required speaker efficiency

Hello,

Gosh, wasn't sure if to post in the speaker or amp sections. But here it is. 

I've got a Finale/Triode Lab F-300B Monoblock amp paired with the Omega Super Alnico monitors stated at 94.5db efficiency. It does very well with this amp and I'm very happy with the pair overall. With classical being 90% of what I listen to, I guess I haven't really pushed the system to its limits, but it delivers plenty of what I like with acoustic instruments. Harmonics (texture and timbre), tone, minor dynamic shifts (musicianship), etc.

My question is for SET 45 tube owners and recommended speaker efficiency. Do the 2 watts from these amps have a 'real world' threshold where they simply can't deliver under a certain efficiency rating? So, for example, my speakers state 2 watts and up are enough. But I've had a few people tell me that 94.5db is not enough for this SET. However, on the Decware site, it does put a pair of Omega speakers on it's site as, what I imagine being a suitable speaker to pair with their 2 watt amps. The amp I'm thinking of getting will have Hashimoto transformers and a 20 watt output transformer. Not sure if that will give a bit more for the speaker to use or not. Also, are speakers w/o crossovers something to consider if I need to go look for another pair of speakers? Finally, what would your experience with the 45 SET amp suggest as far as the optimal efficiency rating for these tiny two watts?

Geesh, it's 5:40 am, no sleep yet, please ask a question if all the above sounds like someone hasn't had sleep yet.

Anyway thanks folks, really appreciate any suggestions to an optimal efficiency.

take care,
rob


vvcv
br3098
994 posts
 
Finally, what would your experience with the 45 SET amp suggest as far as the optimal efficiency rating for these tiny two watts?
As with all things audio, it depends. It depends on your ears, your expectations, your gear (listed), the size, shape and construction of your room, how loudly (or softly) you typically play music and, mostly, your ears.

I ran a pair of Omega Super Alnico 6 monitors as my main speakers for a couple of years, paired most often w/ both a 2W 45 SET mono blocks or a 5W SE EL34 amp. I loved them and thought they were great for most non-headbanging music but weren't quite cutting it with large orchestral and opera pieces. Maybe it was the single driver or maybe it was the whizzer cone. I ended up replacing them with something completely different that isn't low-powered tube friendly. That's not to say I don't miss the Omegas - I do.

But to answer your question, 2W is enough when it's enough. And it's not when it's not. If you like the sound of the Omegas but you can't play loud enough, get an amp that puts out more horsepower. I had a McIntosh MC225 (25 W PP) and it really changed how the Omegas sounded. Not better or worse, just very different. If you don't like the sound of the Omegas then changing amps probably won't make you happy. My motto is speakers first: find a speaker you love and will work with your music and your room and then find the right amp to optimize the speaker. Others here may have a different opinion.

thaluza's avatar
thaluza
285 posts
 
I just got a pair of 45 mono blocks and am pleasantly surprised with how they compare to my 300b amps. To my ears, my 45 set amps can play subjectively louder than my 300b's with less distortion. I often don't realize how loud the volume is when I am listening. Maybe the first watt is better?

All that aside, impedance is just as important as high sensitivity in matching set amps with speakers. The 8 ohm rating of your Omega speakers would be good for a 45 set amp if it is a flat 8 ohms with no major dips. A sensitivity of 94.5 db, while not ideal, would work okay too if that is truly the sensitivity of the speakers. Actual sensitivity measurements are usually lower than what the manufacturer provides (see, for example, the recent Stereophile review of the Volti Razz speakers). The bottom line is that I would try to get some real world speaker measurements before proceeding, as your speakers are perhaps on the cusp of what would and would not work with a flea watt amp.
alfagil
7 posts
 
In my limited experience my enjoyment of flea powered amps increased whenever I paired them with speakers of higher sensitivity.  I have a low powered 2A3 (3W) and kt88 (8W).  The sound was good when paired with Zu Omens and got much better with Rethm Maargas.  Greater dynamics and presence, and they could go much louder and with great ease.  As good as the Rethms sound, I’m getting the best sound yet from my Altec 604e.   Now these Altecs have the Werner Jagusch crossovers while the Zu and Rethm are stock and are both rated at approximately 96dB, while the Altecs are probably around 100dB.  
I would pair very low powered amps with very sensitive speakers.     Good luck.  
mapman's avatar
mapman
22,197 posts
 
Like much with hifi, it’s largely a matter of expectations.

Low power SET amps are a very special case though.

To get the most out of just a couple watts of power, you need not just the most efficient speakers to pick up the slack, likely horn loaded, but speakers that are also easy to drive as indicated by phase and impedance charts. Otherwise that will impact the sound quality at all volumes and the speakers may go loud enough but with significantly more distortion as volume increases.

Additionally to get fully extended bass out of just a couple watts, if that matters to you, you need larger speakers.

If you do not have need to go loud and room is smaller, and you are willing to pass on the lowest octaves, that opens up many more possibilities for lower cost.

There is no getting around physics.   The good news however is most music happens in the midrange.......



cal3713's avatar
cal3713
1,421 posts
 
@vvcv Just a quick comment regarding switching binding post terminals. If you're getting in there and modifying the speakers and amplifiers, you might consider just replacing with wago lever clips instead (I use 221s).

Why spend all the work energizing a big metal piece with a sloppy mechanical connection when you can just switch to a high tension, small piece of pure copper that can take a 4kV surge?  Less likely to come loose than most binding posts and about as close to direct soldering as you can get. They don't look as fancy, but highly preferred in lieu of terminals for me...

https://www.wago.com/us/lp-221
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