Basic question about sensitivity

The B&W 800 series are a good example of speakers that are relatively efficient but difficult to drive.

@yoyoyaya , I am running an ancient (going on 30 years old) pair of B&W 805s; I just took a look at the literature that came with them, and it states that the sensitivity is 87 and nominal impedance is 8 ohms. Since I have owned these speakers, I have ran them with three different tube amps, and am currently running them with one that is switchable between ultralinear and 50 wpc triode, and mostly always I have used the triode setting. I had never thought of these speakers as being particularly hard (for any of the amps I have owned) to drive; but with that typed, the largest room I have ever had them in was probably on the small side of medium, and presently, the room that they are in now is just plain SMALL.

Higher efficiency = easier to drive.

Higher sensitivity = more output at given voltage.

When the speaker is 8 Ohms, efficiency and sensitivity are the same.

@erik_squires , thank you. The Monitor Audio Gold 300 5G (sensitivity 90) minimum impedance is stated to be 3.5 ohms, which would then explain the need for more power.

@ghdprentice , thank you; I am curious, when you refer to the Harbeth as a "specialty speaker," what do you mean by that.

Thank you for responding @ellajeanelle , no, I wasn’t confusing impedance with sensitivity; however I was not understanding the relationship between the two.

@ditusa , thank you for the link. I read through it quite quickly and it does appear to be quite informative. I am going to give it a careful thorough read.

4. Specific Amplifier Requirements: Harbeth speakers have a nominal impedance of 6 ohms, which can be a challenge for some mainstream amplifiers. These amplifiers may not deliver enough current to drive the speakers to their full potential, potentially resulting in a less dynamic and detailed sound. This requirement for specific amplification options limits their accessibility to a broader audience, but it also attracts audiophiles who enjoy the challenge of pairing their speakers with compatible equipment to achieve the best possible sound.

 

Thanks, @ghdprentice , I am running a Cary V12 which is switchable between 50 wpc triode and 100 wpc ultralinear. I am currently running it in triode, and honestly, I do not think I would want to pair it with anything that I could not drive in its triode setting.

and a cabinet that contributes to….. output…not present in the…. input

@tomic601 , can you expound upon that?

Thank you to all for the informative responses.

@yoyoyaya  , thanks, that's interesting (particularly since I am kicking around the idea of upgrading).

Given that my 805s are going on 30 yeras old, and taking in account for inflation and technology, how far do you think I'd need to go to make a significant upgrade?

@yoyoyaya , my amp does have 4 ohm taps. Do you think that might compensate for "tough impedance/phase dips in the bass and low midrange"?

And what did you mean by

though they are a bit polarising

?

I went back and had a look at John Atkinson’s measurements for your V12. On paper, even accounting for the 4 Ohm tap, they don’t look like an ideal match for one another - due to the tough load and limited efficiency. However, a lot depends on what kind of music you listen to and what volume you listen at.

Wow, thanks, @yoyoyaya ! I suppose I should be looking at something with similar specs to my current but aged 805s (sensitivity of 87 or greater and 8 ohm minimal impedance). My online window shopping I have been doing at Music Direct was starting to focus on the Wharfedale Elysian 1 with AMT tweeter, but considering the specs, a nominal impedance of 4 ohms and minimal impedance of 3.8 ohms (sensitivity 89) that impedance might make them tough for the Cary.

I will say that right now, and probably for some time to come, my listening is happening at a fairly near field in a small room, and usually consists of smaller jazz or folk presentations usually featuring a female vocalist and I am not cranking it to excessive levels.

I wonder if Klipsch should be on my radar at all? A while back ago in another thread I had asked about impressions of the Mobile Fidelity Source Point speakers, and @soix had recommended Joseph Audio Prisms and even sent me a link for a used pair. I haven’t contacted the seller about an audition period yet, but I wasn’t ruling them out, either.

Any significant upgrade with modern speaker can turn out a downgrade so take that into consideration. It was the best monitor they've ever produced. They're easy to drive with tube amps, because of their stable impedance. 

Thank you for responding @czarivey  , to be totally honest, I do not have a great understanding about this hobby, but I suppose in one respect, I am like most everybody else, and always wondering what the weak link is and what it would sound like if I upgraded past it.  When I bought those B&Ws way back in nineteen-ninety-something, I was so happy with them that I didn't even think about them as a weak link and I kept on upgrading the electtronics in front of them, and lately I was thinking that I had the front end to speaker ratio skewed.  And that is what prompted the recent "windo shopping" I have been doing.

@elliottbnewcombjr , if my memory serves me (and it may not), ARC was claiming that the VTM120s with four 6550s in each one were making 100 wpc.

In retrospect, I think that they sounded great. They could rock the house or whisper real quiet or just play sweet and smooth. My aural memory is probably not the most accurate, but now I think that they probably outperformed my current Cary V12 that I replaced them with. What I did not like about them (and I am not at all saying that this is applicable to all ARCs or even all VTM120s) was their reliability (or lack thereof). Every so often (and by that I mean way more often than once in a blue moon) on start up one of them would blow a grid resistor. It usually sounded like a lady-finger firecracker going off, or maybe not quite that loud, but it meant I had to get whichever was the offending amp down, put it on a table, pull the bottom panel off, and desolder the blown resistor from the circuit board and resolder in another one, of which I started keeping several on hand (I seem to remember them being 75 ohm resistors). It wasn’t the end of the world, but it wasn’t a great way to start a listening session. It got to where I would cross my fingers and grit my teeth when I flipped the switches. And most of the time I got my wish and they started up without incident; but a failure happened often enough that it was always on my mind.

By contrast, that Cary V12 that I replaced them with is super reliable. Occasionally it will blow an AC power fuse when I turn it on. Early in its life one of the output tubes went down, and a few years ago one of the signal caps failed, but all in all it is a very reliable amp, and I have had a lot of fun with it over the years.

Any significant upgrade with modern speaker can turn out a downgrade so take that into consideration. It was the best monitor they've ever produced. They're easy to drive with tube amps, because of their stable impedance.

But if you are sill happy with your 805s, I wouldn't be rushing out to change them.

@czarivey  and @yoyoyaya  thanks, that might be the best advice for me to live by for the time being.