Potential performance loss using a manufacturer specified 8Ω only amp, with 4Ω speakers (Dunlavy SC-IIs)

[neph]

I have been using a 100W Yamaha RN303D amp with my Dunlavy SC-IIs. The amp is the entry-level model, which the manual and on-device marking specify to use only with 8Ω speakers, although the manual provides power figures for 4Ωs. Its well-known bigger brother, the RN803D, does not have such limitations.

The Dunlavys are specified at a nominal impedance of 4Ω, with a minimal of 3Ω and max 7.5Ω. I couldn't find the impedance graph for SC II's but the graphs for the slightly smaller SC-Is is as follows:

I haven't felt any amp overheating or sighs of clipping. The is sometimes a hardness in the low mids, but this may have to do with the combination of placing the speakers close to the side walls and 1st order quirky polars. I feel that in some cases, low and mid-bass may be a bit underwhelming but this is not universal for all tracks.

Is it possible that there is performance loss especially in the bass, given this impedance mismatch? Will a quality class D amp provide any noticeable improvement in quality?

 

[DonH56]

I have been using a 100W Yamaha RN303D amp with my Dunlavy SC-IIs. The amp is the entry-level model, which the manual and on-device marking specify to use only with 8Ω speakers, although the manual provides power figures for 4Ωs. Its well-known bigger brother, the RN803D, does not have such limitations.

The Dunlavys are specified at a nominal impedance of 4Ω, with a minimal of 3Ω and max 7.5Ω. I couldn't find the impedance graph for SC II's but the graphs for the slightly smaller SC-Is is as follows:

I haven't felt any amp overheating or sighs of clipping. The is sometimes a hardness in the low mids, but this may have to do with the combination of placing the speakers close to the side walls and 1st order quirky polars. I feel that in some cases, low and mid-bass may be a bit underwhelming but this is not universal for all tracks.

Is it possible that there is performance loss especially in the bass, given this impedance mismatch? Will a quality class D amp provide any noticeable improvement in quality?

There is no "impedance mismatch" in the sense you are thinking. Most "8-ohm" amplifiers will drive 4 ohms with little to no problems as long as they do not have to deliver too much power, exceeding their current or thermal (heat) capability. If the amp is not overheating and you do not hear clipping consistently (usually creates a harsh high-end sound) then you are fine. The harshness and "underwhelming" bass is likely from the source recording since it is not present on everything.

You can check on online SPL calculator to estimate how much power you might be using: http://myhometheater.homestead.com/splcalculator.html

Human perception is very easily fooled into thinking there is improvement when there really is none. A new amp (or whatever) often sounds better because we expect it to, and because we tend to turn it up and listen with more focus. A tiny increase in volume will make it sound better, and by focusing more on the music (movie, etc.) we will often notice new things even though they were there all along. Many times I have noticed profound differences when adding a new component, only to discover level-matching made the differences go away, and the "new" things I heard were there all along (new amp or old).

And, of course, there are times when a new component really does make a difference. Marketing thrives on that, and exaggerating the differences ("night and day" change is very rare IME/IMO), so it pays to be cautious.

HTH - Don

 

[Head_Unit]

Yeah everything @DonH56 said agrees this speaker engineer. Does your amp get hot?
- You can check if it's clipping-you need to find/download a 300-400 Hz "0 dB" tone and you need a good AC voltmeter. If you have/get those reply and I can go into more detail.
- For more decibels of power than 100W/8Ω you'd need 300+ watts into FOUR ohms, that is the important rating even if the speakers were 8Ω.
- More power will not help bass response one iota. A different amp might interact differently with the speaker impedance and give a different tonal character but I don't believe in "night and day" massive changes aside from swapping speakers.
- Measure your in-room response. REW + UMIK-1 or to start with a phone spectrum analyzer app. I feel many "speaker" or "amp" etc problems are more likely room/placement problems.

 

[JSmith]

Dunlavy SC-IIs

Some fine speakers you have there.


JSmith

 

[neph]

Thank you for the replies

@DonH56 I agree with you. I am not searching for any magic solutions and I am aware that the most noticeable improvement will come from subs. I just got extra cautious due to the manual explicitly mentioning 8Ω only.

@Head_Unit I have a Fluke 289 that measures RMS of AC voltage and current. I suppose this is to measure power consumption and see if we get close to the amplifier's maximum output.

@JSmith Thank you. I am a fan too and I haven't heard anything that comes close in terms of natural sounding, to put it objectively.
However, I think that in terms of design philosophy (1st order crossovers to achieve perfect impulse and time coherence), they are considered anachronistic since polars get messy and ears supposedly can not discern minor timing delays of a few ms.

I have a gut feeling that if Amir was to test some Dunlavys, a headless panther would appear. I would pay good money to crowdfund a Dunlavy shipped to Amir for testing...

 

[Brent71]

I have a gut feeling that if Amir was to test some Dunlavys, a headless panther would appear. I would pay good money to crowdfund a Dunlavy shipped to Amir for testing...

I would hope not that there'd be a headless panther. Stereophile did reviews of the SC-I, SC-IV, SC-IV/A and SC-VI, and all of them got excellent reviews. Step response and impulse response were about perfect, and the frequency response, phase angle and impedance measurements were all excellent. Audio magazine did a review of the SC-V, but the review didn't have the thorough measurements of the Stereophile reviews. John Dunlavy claimed that the SC-V was the most accurate speaker he ever built, so the measurements of the SC-V should be even better than those of the SC-IV and SC-VI, which are already awesome.

Audio Magazine's glowing review of the SC-V (page 71): www.worldradiohistory.com/Archive-All-Audio/Archive-Audio/90s/Audio-1999-03.pdf

 

[AudioX3]

I would love to see a review by Amir, and quite honestly if it came out bad it would bring up a very interesting point. Amir's test have the mic very close to the speaker. Dunlavy, a speaker genius engineer who very much has Amir philosophy on flat response and anti snake oil, but Dunlavy designed all their speakers to perform at 10 ft from the listener for anochronic chamber alignment at precisely that point. He optimized to this every single speaker in an anochronic chamber before releasing to be ruler flat and time aligned at 10 ft. I always wondered if that would be a flaw in using the standard speaker testing Amir does at close range circling the speaker with the Dunlavy's. Both Amir and Dunlavy are true engineers and principled and I believe they would have gotten along quite well (alas John Dunlavy no longer is of this earth). If these speakers came out headless, then it would be the one time I would question the testing method validity for what Dunlavy designed. I think Amir might ponder as well.

PS: I certainly am not shipping my SC-2s for testing that for sure, nor the SC-1 AV center. Rare, heavy and bulky!

PPS: The results are stunning imaging, but your head is in a vice not to move an inch. The real use for this design is as a studio monitor and they are treasured by engineers for such. For every day listening, I have open baffle Spatial Audio M4 Turbo S. Another speaker I would love reviewed but not volunteering mine as just could not risk damage. Open Baffle is much more tolerant for a larger sweet spot and are stunning though less super precise on imaging as the Dunlavy (though quite good). Its nice to have both as options.

 

[Blumlein 88]

I would love to see a review by Amir, and quite honestly if it came out bad it would bring up a very interesting point. Amir's test have the mic very close to the speaker. Dunlavy, a speaker genius engineer who very much has Amir philosophy on flat response and anti snake oil, but Dunlavy designed all their speakers to perform at 10 ft from the listener for anochronic chamber alignment at precisely that point. He optimized to this every single speaker in an anochronic chamber before releasing to be ruler flat and time aligned at 10 ft. I always wondered if that would be a flaw in using the standard speaker testing Amir does at close range circling the speaker with the Dunlavy's. Both Amir and Dunlavy are true engineers and principled and I believe they would have gotten along quite well (alas John Dunlavy no longer is of this earth). If these speakers came out headless, then it would be the one time I would question the testing method validity for what Dunlavy designed. I think Amir might ponder as well.

PS: I certainly am not shipping my SC-2s for testing that for sure, nor the SC-1 AV center. Rare, heavy and bulky!

PPS: The results are stunning imaging, but your head is in a vice not to move an inch. The real use for this design is as a studio monitor and they are treasured by engineers for such. For every day listening, I have open baffle Spatial Audio M4 Turbo S. Another speaker I would love reviewed but not volunteering mine as just could not risk damage. Open Baffle is much more tolerant for a larger sweet spot and are stunning though less super precise on imaging as the Dunlavy (though quite good). Its nice to have both as options.

I'm pretty sure the Dunlavy would do at least pretty well on a spin-o-rama. Also the way the Klippel works is like doing tests in an anechoic chamber. Even better in some regards. It can calculate what the speaker is doing at a distance. Harman's idea of designing a speaker people will find better is not from a Klippel, but rather from comparing spins of speakers tested at 70 points around the speaker in anechoic conditions. The Klippel came along later as a way to get the same results without the chamber. That is does so with up close measuring over many more points is quite a feat of design.

Here is an illustration of how the spins are measured in a chamber. Every 10 degrees horizontally and vertically. The ANSI standard says measures are done with the microphone at 2 meters (about 6.5 feet). See page 10 and following pages. The Klippel measures many more points and can give results the same as if measured at greater distance.

https://www.audiosciencereview.com/forum/index.php?attachments/ansi-cta-2034-a-pdf.45978/

 

[Daverz]

The Klippel does use nearfield measurements, but uses them to mathematically compute an anechoic response. It don't believe getting accurate measurements of the Dunlavy's would be a problem for it, other than possibly their height (and the weight of the big ones) causing a problem.

However, they may not do very well off axis. I can only find off-axis measurements for the SC-I and SC-IV/A:

Dunlavy Audio Labs SC-I loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

Dunlavy Audio Labs SC-IV/A loudspeaker Measurements part 2

John Dunlavy has always emphasized that the vertical spaced array nature of the drive-units in his designs means that the speaker's reference on-axis will not be achieved at distances closer than 8'. Unfortunately, the physical restrictions placed on my speaker measurements by Stereophile's...

www.stereophile.com

(I have a pair of unused SC-IIIs sitting behind me, but I'm not going to try to ship them.)

 

[Brent71]

(I have a pair of unused SC-IIIs sitting behind me, but I'm not going to try to ship them.)

I have unused IIIs, IVs, and Vs, but they're not going anywhere either. My first pair of Vs arrived with dead tweeters and mids, no idea why. I bought replacement drivers from Madisound, and they sound great, but it bothered me that they weren't matched like when they left the factory. About 2 years later, when another pair of Vs came up for sale for a really good price, I grabbed them.

 

[Brent71]

PPS: The results are stunning imaging, but your head is in a vice not to move an inch. The real use for this design is as a studio monitor and they are treasured by engineers for such.

I've never had that issue with any of my pairs of Dunlavys, and can move my head a decent amount before it becomes very noticeable. I've had them all setup in roughly the same spots, with the same amount of toe-in, and it works great. My living room is 11.5 ft x 20ft, 8 ft ceilings, carpeted floor, listening spot just under 11 ft from the speakers, and toed-in so I can't see either side of the enclosures. Because of the doorways in my living room, I have them setup on the short wall. I have them close to the corners with the tweeters 21" from the side walls, 34" from the front wall, and homebrew 2' x 4' panels made out of 2" thick O-C 703. I know the positioning is counter to what JD recommended, but they really do sound incredible how I have them setup now; imaging is awesome, and the phantom center is so good you'd swear there's an invisible CC speaker.

 

[AudioX3]

I've never had that issue with any of my pairs of Dunlavys, and can move my head a decent amount before it becomes very noticeable. I've had them all setup in roughly the same spots, with the same amount of toe-in, and it works great. My living room is 11.5 ft x 20ft, 8 ft ceilings, carpeted floor, listening spot just under 11 ft from the speakers, and toed-in so I can't see either side of the enclosures. Because of the doorways in my living room, I have them setup on the short wall. I have them close to the corners with the tweeters 21" from the side walls, 34" from the front wall, and homebrew 2' x 4' panels made out of 2" thick O-C 703. I know the positioning is counter to what JD recommended, but they really do sound incredible how I have them setup now; imaging is awesome, and the phantom center is so good you'd swear there's an invisible CC speaker.

Thx. I will try some more experimenting as get around to it. I can say I have done several stabs at it and its been a while since I have tried again as the head in a vice thing basically took them out of rotation for a year as of now. I am totally in awe of the Spatial M4s and they are much easier to setup and a wide sweet spot. The Dunlavy by design are to be a norrow sweet spot, but an inch of movement is toooo refined. But you give me hope and greatly appeciate the insights. I am setup BTW along the long wall which Dunlavy recommends and is really the only arrangement for my room that makes sense which otherwise BTW has nearly identical dimensions as yours. I have no treatment and my listening position is right against the back wall so that is further obstacles someday to address. Again, thanks so much for your insights and I will post when I give it a try again in a few weeks and let you know the results. Appreciate the community.

PS: If I get it nailed, I may be kicking myself for not picking up another pair for $500 or less as obo. It was so tempting but I am learning not to keep collecting and am finally getting over the hump I think. Its so hard, especially with speakers and CL deals that one knows they can resell for more so $s not the risk. But they just collect and time to pare down and let someone else enjoy a great deal.

 

[AudioX3]

I have unused IIIs, IVs, and Vs, but they're not going anywhere either. My first pair of Vs arrived with dead tweeters and mids, no idea why. I bought replacement drivers from Madisound, and they sound great, but it bothered me that they weren't matched like when they left the factory. About 2 years later, when another pair of Vs came up for sale for a really good price, I grabbed them.

You gotta laugh what it would be like for a SC-V arriving at Amir's (let along a pair) and let Amir put it on the side somewhere until gets around to testing. The image has me LMAO.

(As for you, I take it you got a lot of room to leave that collection of Dunlavy's sitting around.)

 

[witwald]

The real use for this design is as a studio monitor and they are treasured by engineers for such.

I wonder which recording studios and mastering labs use the Dunlavy loudspeakers?

 

[AudioX3]

I wonder which recording studios and mastering labs use the Dunlavy loudspeakers?

Well got me but here is one mention

..... The strive for accuracy by Dunlavy to a precise location makes for a studio monitor though the Dunlavy's are not meant for near field and the cabitry furniture grade finish are more towards a luxury end user. So if a studio mixer/master has the space and the cash... Its hard to descern in the end who would be the company's target purchaser in mass. In the end Dunlavy created what he built for an ideal. Dunlavy speakers requirement for space and distance are definitely a challenge. He has the credentials, but i don't think any large speaker company would be hiring Dunlavy for mass production design or profit. In sumary he was an artison for those who appreciated ideals to sum it up in my best i can turn a phrase.

 

[Brent71]

I wonder which recording studios and mastering labs use the Dunlavy loudspeakers?

David Glasser at Airshow Mastering uses Vs and IVs. https://airshowmastering.com/the-studio/

 

[Brent71]

Dave Harris - Studio B Mastering, uses a pair of Dunlavy SC-V.