15 ohm speakers yea or nay?

I just bought Falcon speakers that are 15 ohms. I have Harbeths that are 6 ohms. Both have the same sensitivity rating of 83db. I am using both with the same tube amps.

What has me scratchin’ my head is that the Falcons are much louder with the volume set the same on my preamp.

Any opinions on why a 15 ohm speaker would be that  much different than a 6 ohm speaker with the same sensitivity specs?





     What impedance tap choices do your tube amps have?

     Bearing in mind some are internal: which are you using?

     I hate to type, thus: see if any of this helps-



4 and 8 ohm taps. I am using the 8 ohm taps for both speakers!

Thanks for that site!


Efficiency and sensitivity are not the same. My speakers are JBL 4435 monitors and have a sensitivity of 96 dB SPL @ 1 watt @ 2 meters @ 8 Ohm and have an efficiency of 2.7%. See the JBL manual below specifications section, last page. As for the difference between sensitivity and efficiency see the link below JBL technical note first page section C. All three specifications, impedance, sensitivity and efficiency are important and must be looked at together to better understand their meaning and correlation to what you hear. Also, amplifiers produce more distortion in lower impedances then higher impedances. Hope that helps. 😎





@rodman99999 +2. Great article.

I would say Yea.  Because the only speaker that I know that has 15ohm and 83db spl ratings with the Falcon name attached is their Rogers LS 3/5a speakers.  After 40 years and many speakers have come and gone, I still love Rogers.

Now that you mention.  I do switch between 8ohm Quads with 86ish?db spl and the Rogers.  I don't hear any significant loudness between them with the same volume setting on the preamp. 

However, I did hear a hear a level difference when I went from a tube amp using the 16 ohm tap to the SS Spectral amp I'm using now.  I just figured it was the differing input sensitivity of the amps.

Why?  I don't know.  I just listen to the music.  I do use the Quads for large orchestral.  The Rogers for near field critical listening, smaller quintets, jazz or solo recordings.

If the Falcon speaker is their LS 3/5a, it has a minimum impedance of just over 7 ohms and Hi Fi News rated it as an 8ohm design. Also, it has a big peak in frequency response over 10k. Taking those aspects together, it might sound louder, partly through being optimally matched to the transformer tap and partly subjectively. It would be interesting to put an SPL meter on both speakers and see what it reads.

The Falcon Q7 are the speakers that I am using. They play much louder compared to my Harbeth P3 ESR!!

NEW! Falcon Acoustics Q7 “Complete@Home”LOUDSPEAKER SYSTEM

Falcon Acoustics is pleased to announce the re-introduction of the Falcon Acoustics Q7 “Complete@Home” Loudspeaker system. Designed by Malcolm Jones and sold by Falcon for many years, the updated Q7 features the same Falcon B110 and T27 drive units as used in the Falcon LS3/5a in a specially extended LS3/5a-type cabinet to produce an optimum Q=0.7 system with extra bass compared to the LSA3/5a (+2dB @ 50 Hz).

All you need is 1-2 hours to complete your own fully-specified loudspeaker system. Italian full “Production Grade” birch ply cabinets with veneered front panels and magnetic location for the cloth grilles. Falcon 23.2 factory-assembled pre-wired crossovers. No soldering required. All tools provided. An online Instruction Manual and YouTube video will guide you at all times.

The Falcon Q7 features matched pairs of Falcon B110’s and T27’s, a pair of factory-assembled Falcon 23.2 crossovers, and full Production Grade birch ply Italian cabinets in natural Walnut or Rosewood (regret Rosewood sold out for now) veneers. Made in the same factory as the renowned Falcon Acoustics BBC LS3/5a. Similar voicing to our LS3/5a but with extra bass extension.

Specially designed magnetic Tygan front grilles available.

Factory built options supplied built by Falcon, fully checked and tested are available.



2-Way Infinite Baffle (sealed box). Italian manufactured Plywood cabinet in 12mm and 9mm graded Baltic Ply Birch Cabinet. Natural wood Walnut or Rosewood veneer. Magnetic attached Cloth grille.

Drive Units Falcon B110 (5”) Bextrene Cone bass unit; 19mm ( ¾ ”) Falcon T27 Mylar dome tweeter. Matched pairs

Freq. response 60Hz-20kHz +/- 3dB

Impedance 15 ohms

Sensitivity 83dB/2.83V/m

Power handling 15-50W

Connector 4mm Custom-Designed nickel-plated binding posts

Dimensions(hxwxd) 309 x 190 x 230mm (+12mm for grille and binding posts)

Finish Natural wood veneer - Walnut

Weight 6.0kg each, 14 kgs per pair shipping weight.

Packing Pr speakers per shipping carton

Product Reviews



I believe that many will find that linked article worthwhile.

                                             I hope so!

     The article's SS section should be of interest to those with bridged, stereo amps (being used as monoblocks), when looking for compatible speakers.

                               That's all I would have added.

                          Might be a useful thread, on it's own?

Post removed 

lots of tube amps like 15 ohms but not 4 ohms, and many SS amps do great at 4 ohms but don't like 15...a had a few similarly rated SS amps that responded very differently to my high impedance Zu speakers...

What has me scratchin’ my head is that the Falcons are much louder with the volume set the same on my preamp.

Maybe the Falcons play louder then the Harbeths because a 16 Ohm woofer has a lighter and thinner voice coil then an 8 Ohm woofer. So the Falcons have higher, efficiency, just guessing. 😎



Post removed 

In the 1950’s all amplifiers were tube, and many loudspeakers 16 ohm (nominally). The move to solid state amps and lower impedance loudspeakers at the same time (mid-to-late 60’s) was not a matter of coincidence.

One reason the QUAD ESL sounds better with tube amps is because of it’s insane modulus of impedance. Nominally 16 ohm, but up to 32 ohms at low frequencies, down to 1 ohm at high. Used with a typical tube amp (with their relatively high output impedance, and resultant frequency response deviations), the ESL is missing high frequencies, used with solid state missing bass.

@rodman99999 Great article. Once seen it before, however paid greater attention to it this time.  Used the info to determine needs for my Tannoy Sterlings. The recent review of them in Stereophile did raise some concerns.  I am thinking they may need more power (as current)  than I originally thought.  



@yogiboy These days sensitivity (2.83V/1 meter) is how speakers are measured. There was a time when efficiency (1 Watt/1 meter) was the spec instead- back when tubes were King.

2.83 Volts into 8 Ohms is 1 Watt. That is why the seemingly arbitrary number.

When you cut the impedance in half to 4 Ohms, 2.83 Volts is now 2 Watts (which is a 3dB increase). So the impedance makes a difference! You have one speaker that is 6 Ohms and the other is 15. If the sensitivity is the same, for each doubling of impedance the efficiency is increased. So by my calculations the 15 Ohm speakers should sound about 4.5dB louder because they are 4.5dB more efficient.

When you are talking tube amps, because they can’t double power as impedance is halved (like many solid state amps do) the efficiency spec is more important. That means you have to derive it from the sensitivity spec and the impedance of the speaker. How I arrived at my numbers above is 6 is halfway between 8 and 4 Ohms so that’s a matter of 1.5 dB instead of 3 dB (which it would be if the 6 Ohm speaker were 4 instead).

The difference between 8 and 16 Ohms is its doubled, meaning another 3dB difference. I added the 1.5 to 3 dB to get my answer. Its not quite right since the speaker is really 15 Ohms, but its close enough for government work.


Hi Ralph,

Thanks for the great explanation of why the 15 ohm Falcons play louder than the 6 ohm Harbeths. You are a real asset to the Audigon community!


I use 16 ohm speakers because my amps like them.

Or,...you could say that I use OTL tube amps because my speakers like them.

Yogi, I just purchased a pair of Q7s what amps do you like with them? Cables ? I'm using a Belles 22a pre and 150 ref2 amp. Sounds good but room is really bad very lively. You've had so many different units what are your thoughts?


I sold the Q7. I was using Quicksilver 70 watt tube amps with Audioquest cables. The Q7 is as good as any of that type of speaker. I replaced them with the larger Harbeth HL5 super plus. The Falcons are very lively forward sounding compared to my Harbeth P3esrs. BTW, after the holidays I will be selling the P3s. I hope the Falcons work out for you!

Yogi, what do you think of the bigger Harbeth. When I was in New York I went to Park Ave  and one of the sales people said of all the Harbeths the ones you purchased were the best better than the 40.2  etc. 

I may need a bigger speaker for the area. The listening area is 9x13 but it opens in behind the listening area and to the side of the listening chair. How do you determine if a larger speaker is needed?


I think a larger speaker in that size room would be overwhelming. I have owned the Harbeth C7 and the M30.1 and I preferred the P3 in my 20x15 room sitting 8 feet away. About 3 weeks ago I pulled the trigger on a used pair of the HL5 with TonTrager stands figuring if they didn’t work out I could resell them without a loss.

To my surprise these are the best sounding Harbeths that I’ve owned. The seller found them bright but I sure don’t. You never know until you try a speaker in your room and gear how it will sound!

BTW, have you ever listened to the P3ESR?

I’ve listened to them in a showroom a several years ago. When I went up the line the compact 7s sounded better..

What did you think of the Q7s compared to all your other speaker history. I’ve read nummerous posts by you and you certainly have a great ear. Rebbe also used to post a lot. Any summary of your journey and what systems you miss? Synergy is so important !

 I have an Alan Eaton set 45. A Belles 22a with a 150 ref  2, a nait 2 , a quad 405;with an 303 and an Ampzilla 2. None have speaker assoc with them now. I had the omega 3xrs with the aalan Eaton. Lrs with the David belles. Now I’m using the Q7 with The Belles equipment. Any suggestions?




It sounds like you have fine gear with those Falcons so I really can’t suggest changing anything. I prefer 2 way standmount type speakers. It surprised me that I like the HL5. I haven’t had a 3 way speaker since Vandrsteens many moons ago. I really don't miss any of the speakers that I have owned but I must say that I had a Spendor 2 1/2 way floorstander that I should have kept. BTW, those Falcons are a bargain compared to the many other she box size speakers out there. Enjoy them!

Yogiboy, I’m glad the SHL5 Plus has lived up to your expectations. They are good speakers. I suspect the Quicksilver tube amp brought out the best in the Harbeth. I have used solid-state amps with the Harbeth all my life, about 12 years and the speakers sounded good but not exactly spectacular. Apart from the Quicksilver, the Harbeth also sounds great with Leben.

I’ve recently moved on from the Harbeth to Graham LS5/9. I find the Graham to have better clarity, detail and openness than the SHL5+. I am currently driving the Graham with a Luxman solid state.

Enjoy the Harbeth SHL5+.


Just a follow-up. I sold my Oppo sonica dac and substituted a  Geshelli j2 with the akm4499  and sparkos op amps. What an amazing change. I love the Falcons with the Belles equipment. I also  have a rogue Cronus magnums2 but haven’t tried it. I’m wondering what a Conrad Johnson integrated might sound like.