2. amps-preamps
  3. 158723-123436

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
mapman's avatar
mapman
21,865 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
sdrsdrsdr
196 posts
 
I have had many SET amps with both Avantgarde Trios and Lamhorn speakers. I still own a 45 amp that I sometimes use with my Lamhorns, I have to say there is a big difference in saying enough power to play a system loud and enough power to play a system effortlessly. Also, SET amps change drastically in sound when they are pushed even a little. This is what many people like about them though. 

With my Trios using both a yamamoto 45 amp and wavelength cardinal 300b it was not even close to the powerful 30 watts from my 845 Viva amps. I wouldn't say they were under powered, they did play loud. These speakers are 107 db efficient. Both the lower powered amps seemed to sound  slow in comparison. 

Even with my Lamhorns that I still own: which are single driver crossoverless speakers and 15 ohm,  my push pull amp performs at a higher level with regards to dynamics and prat than with my 45 amp and Art Audio PX-25. Same thing, not even close. 

A speaker that is 100 db efficient, a 45 I would say is being pushed to its limit. I have to say though that these low power tube amps do have a quality that is attractive that's why I still own two. But nothing is a substitute for power.

A good analogy is, is a  50 horse power engine enough to move a car around town. Yes. But not in a high performing way. I remember people giving their opinions about his to me before just as I am now. I recommend to go ahead and try. All part of the hobby and learning experience. 
fatdaddy2
368 posts
 
I've got a pair of backloaded horns using Fostex 208 E Sigma drivers available for local pickup in SoCal, if anyone is interested.  I just want to see them go to a good home  Estimate about 98dB efficiency and worked well with my Moth S45 (45 or 2A3).
vvcv OP
13 posts
 
I know how you feel about wanting to see gear go to a good home. I’ve had a couple of limited production amps that I purchased for the investment. Wow, and did I ever get a great trade with one of them. I’m still shaking my head. But, I did start to enjoy the amp a lot. But, they promised to keep it in the family for a very long time.

Anyway, great people of Audiogon. I just want to thank all of you for all the great information (my favorite audio source of information). I’m now traversing page after page and getting speaker choices narrowed. But, thanks to you guys, I feel much more comfortable making the right decision in pairing speakers with this certain amp.

Take care!
More to discover