Can SuperUniti/Nova drive low-impedance B&W 804 D3?


Question to Richard Dane or Phil Harris:

The new B&W 804 D3 has a very low impedance of 1.3 Ohms at 100-200 Hz In the range between 80 and 1000 Hz the impedance is below 2.5 Ohms. On the other hand there is an impedance peak of 12 Ohms at 45 Hz. See this multi-speaker test (in Dutch).

1) Will the Uniti Nova and the SuperUniti be able to drive this low impedance speaker? (of course using short and high gauge cables)

2) Is there any difference in amplifier performance between Superuniti and Nova? Size, weight and amplifier data look very similar.

3) How can I hear/detect a poor match between amplifier and this low-impedance speaker?

Best regards,


Original Post

Bert, it's probably a question best asked of Naim or perhaps a dealer who specialises in both Naim and B&W.  That minimum impedance sounds pretty low. B&W say on their site that the speaker is a nominal 8 ohm impedance with a minimum of 3 ohms.

I do recall in the past that the crossover in the 800 series necessitated a modification to the protection circuitry of the Naim amplifiers as otherwise they would either trip or just perform poorly.  The amps were otherwise essentially unchanged as was performance, and it became standard in production. After that, no problems.

I would avoid high capacitance speaker cables - low capacitance and moderate inductance is Naim's recommendation - and keep them long rather than short. I would suggest 5m or more each channel. 

p.s. I've removed the link.  Please don't post unauthorised links to reviews or commercial websites in the Hifi Corner, thanks.

Granted your query was directed to two individuals, but for my two cents worth I'd offer this;

1) "driving" speakers is all in the ear of the listener and any speaker, regardless of ratings, will perform better with more watts, Better command and grip, especially at lower volume, and especially at the bottom end,

2) with 80-W on the Superuniti you're sitting at the low end of the 804's range of 50-200-W, and I'd rather be on the high end or over the limit,

3) an amp rated over the defined speaker limits is no problem provided you don't go to excessive volumes, and is invariably a boon to speaker performance,

4) I'd look at either a more powerful amp or different speakers, which is more important to you?

5) dissecting impedances at different frequency ranges and associated cable gages doesn't seem a fruitful path to musical satisfaction, nor is there a real answer out there.


Point 1-2-3 very well taken, a powerful amp will control a speaker very well. Just don't blow it, by simply capping the output (max volume) of the pre-amp.

4.   I have noticed over the years that speakers are much more important than any other component on SQ and 'musical satisfaction', that's why I spend most of my money to speakers. Anyway, this weekend I will audition the combination Nova/804D3, and hear them out!.

5.   1.3 Ohms is very low, and I want to make sure I don't operate the amp in a way it was not designed for.

Cables remain a mystery for me. I read about the magical properties Impedance, Capacitance and Inductance, but I seldom see these parameters specified as requirement by amplifier or speaker, nor specified as property by the cable vendor. Inductance Unit of Measure = uH per meter, Capacitance UoM = pF per meter.

Many poor Hi-Fi-souls like me have no clue what capacitance/inductance the amp or speaker needs, nor what the cable delivers... "Is there anybody out there" on the form who can help us?



I went with a friend to audition speakers for his Nova recently. I think that those impedance figures would mean that D3's are too much speaker for the Nova to drive really well. They are surely designed with more powerful, higher end amps in mind. Even though the Nova is a great piece of kit with good control and refinement, it cannot work miracles where a powerful dedicated amp is more suited.

Some notes on the speakers we listened to with the Nova:
- Neat Motive 3: Do push out a lot of bass for a small speaker, but ultimately would struggle to fill medium/large size rooms. Sounded a little unrefined even harsh in upper mids.

- Focal 926: A nice match, overall sounded very good although missing the last pinch of realism so fell just short of maximum engagement.

- Dynaudio Excite X34: Nice balance, punch etc, a lot of people would like this combo, but timing sounded a little slow/off compared to the best in group

- Proac D48: Really nice although sounded a bit too much speaker for Nova. Timing good, bass very full but could overpower smaller rooms (not sure if this was really the Nova/D48 or a factor of the demo room). Only tried these more expensive speakers as the dealer had a consignment set. The DT8 or smaller D series is probably a better match but this combo was good.

- Q Acoustics Concept 500: Best of the day, these do not sound like box speakers. Balance, punch, timing, realism, engagement all spot on. Treble is not as forward as most modern speakers which to me is a good thing. They might sound slightly rolled off in a very damped room, but should work great in an untreated or lively room. This combo allowed us to hear subtle changes in the musical ebb & flow, pitch and force of tracks better than most speakers I have heard.

- Quad S-5: (Nova with my speakers in my room): This is also a great match. Creates a really deep and 3d soundstage, music floats free of the speakers to fill the room, sounds natural and well balanced. Very engaging combo, may work better than Concept 500 in a highly damped room as it's a bit brighter/airier at the top end, but both give a great sense of the instruments/voices/space within the recording and let music just flow into the room. .

The law of diminishing returns applies - The Nova/Concept 500s is a wonderful sounding combo, but the Quad S-5's are so close at half the price they become the better value proposition. Both need at least 75cm behind to allow ports/ABR some space.

analogmusic posted:

well the concept 500 is a very expensive speaker ...  4000 GBP?

I'd look into Focal Electra 1028 BE for that kind of money. It's a fantastic speaker.

Not so expensive in the context of the B&W 804D3 which the OP is looking at. And decent value given the real progressive cabinet engineering used, and its obvious positive effect on sound quality. 

I see far too many very expensive square boxes still built with MDF of less than 20mm, and from the ones I've heard, the box resonance is almost always audible in these, messing things up regardless of any advanced drivers used. I exclude Harbeth from this complaint as they are properly designed to use the thin-wall box resonances in their overall sound.

I haven't heard the Electras, they look like a good design but the Focal 8xx, 9xx and Sopra's I've heard never quite got me completely engaged or lost in the music.

Mr DC71,

Thank you so much for your detailed listening report, with a strong list of speakers tested with the Nova - very nice.

To be honest, I'm biased towards B&W, having owned 804D2 and now 802D2. I now need a new set for a move to a smaller apartment, that's why I'm interested in the (hopefully even better sounding) 804D3.

Your winner Q Acoustics Concept 500 is 60% of the price of 804D3.... mmm... sounds interesting!

Anyway, tomorrow I will audition the Nova/804 combination, pushing the Nova to its limit .  I will let you know the verdict.

Had a great audition on the Uniti Nova, driving the B&W804D3. Previously I owned the 804D2 and now a 802D2, both driven by a NAP250. My verdict:

The Nova is an smart but expensive piece of engineering. It sounds wonderful in combination with the 804. It's operator-friendly, with a 'Favourite' button for your preferred ratio stations or other inputs. A nice feature is the HDMI input, which allows you to control the Naim volume via your TV remote, rather than juggling with two remotes.

Also the artwork on the screen is quite addictive.  Suddenly the 'classic' line with its stacked boxes looks old-fashioned and so twentieth' century..... It's like comparing a Nokia with an iPhone .

The only issue I have is the shiny remote control, which is not as solid as the previous remote, and is extremely sensitive to fingerprints. Not an improvement.

I started this topic being concerned about the very low impedance of the 804, but this was no issue for the Nova up to 60% volume. In our medium-sized room there was not any need to go louder! So I have no more worries about the ability of the Nova to drive low impedance speakers.

The combination with 804D3 sounds wonderful. The sound stage is very precise with a detailed stereo picture. Positioning of instruments and vocals is very accurate, much better than the 804D2. When you're sitting close it's like wearing a headphone!

The 804 shows fantastic high's and mid's. Instruments like flute, violin, acoustic guitar, trumpet and all voices sound very natural. A great speaker for acoustic and classical music.

I found the diamond tweeters of the 804D2 and 802D2 (Diamond series) somewhat too bright/harsh, and have dampened them by putting a piece of cloth under the tweeter protection cover. No need to do this with the D3, the balance with the mid-range has really improved. Still, the overall sound impression is a bit forward/bright, so the system may sound better in somwhat dampened room (curtains, rugs etc)

Obiously you miss out some heavy bass/body, which becomes clear when listening at heavy rock, symphony orchestra's or grand piano's. For a more full sound you would need its bigger brothers 803/802 driven by a 250 or 300.

Overall this set is an improvement compared to SuperUnit+804D2 or 250+804D2 on musical refinement, sound stage and looks.

No worries mr Analogmusic, an easy and zero-cost solution!

With scissors I cut a small circle from the black cleaning cloth which B&W provided with the speakers, put it on the inside of the magnetic cover, ensuring it did not touch the diamond tweeter and done . It may reduce the high treble by only 1 dB, but it just sounds a bit better to my ears.

When my hifi friends visit me I take it out because they like it better without. It's a subtile difference.

analogmusic posted:

blimey again..... I used to own a B&W 805S speaker, and rather than put a cloth on the tweeter, I just sold them and got Dynaudio's (which I am very happy with)....

I've been thinking about going back to B&W 804D3, but blimey, need to carefully audition.


You will not be disappointed. As I found out the 804D3 does not have this somewhat bright tweeter of the D2/Diamond, it's a very balanced speaker. Go & check it out!

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