Omega Speaker Efficiency

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roscoe65

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Omega Speaker Efficiency
« on: 17 Feb 2017, 05:55 pm »
There have been a number of posts discussing the efficiency of Omega speakers on this and other forums.  I thought I would offer some points of discussion regarding speaker efficiency:

Efficiency vs. Sensitivity

Loudspeaker Efficiency refers to the efficiency in converting electrical power to acoustic power.  The typical standard is the sound output in decibels measured at one meter when driven with an electrical signal of one watt, expresses at dB/W/m.

Loudspeaker Sensitivity refers to the efficiency of converting an electrical voltage input to acoustic power.  The typical standard is the sound output in decibels measured at one meter when driven with an electrical signal of 2.83 volts, expressed as dB/2.83V/M.  This derives from 1W = (2.83V)2/8 ohms.

Loudspeaker Impedance

Loudspeaker impedance is nominal; speakers are not resistors and their impedance derives from a combination of resistance, capacitance and inductive reactance which varies with frequency, crossover elements (if any) and the effects of the bass enclosure.  Calling a speaker an "8 ohm speaker" is more of a convenience than an absolute measurement.  The IEC standard for stated loudspeaker impedance is that where the minimum impedance is 80% of nominal impedance.  That implies that an "8 ohm ohm" speaker will have a minimum 6.4 ohm impedance within the stated frequency band.  However, loudspeaker manufacturers tend to play fast and loose with their specs, both for efficiency and impedance. 

Louis states his Super 3 single driver series as having an 8 ohm impedance.  I haven't measured the speakers myself, but by IEC standards the speaker impedance will be a minimum of 6.4 ohms.  However, if the minimum impedance is 8 ohms, the speaker should be more accurately described as a 10 ohm (nominal) speaker.

The Super 3HO speaker adds an additional driver only below 500hz through the use of a low pass filter (single inductor in series with the helper driver).  This second driver should have little effect on the impedance above 500HZ where the inductor impedance rises dramatically.  However, both drivers will be in parallel below 500hz, theoretically halving the impedance.  If the impedance of a single driver were 8 ohms, both drivers in parallel would be 4 ohms.  But again, these drivers are not resistors.  If we use the Fostex Fe127e as a proxy for the RS5 driver, we see its impedance minimum of 8 ohms from 300-500hz.  Simply putting the drivers in parallel would give us a minimum impedance of 4 ohms, and by IEC standards a 5 ohm nominal loudspeaker.  But in this same 300-500hz region we still have the first order effect of the inductor in series with the second driver, rising its effectly impedance slightly.  As long as this impedance trough is 4.8 ohms at its minimum, Louis' assessment of this as a 6 ohm nominal speaker is accurate and honest.

Driver Efficiency vs. Loudspeaker Efficiency

Both loudspeakers as a system and loudspeaker drivers themselves have a characteristic efficiency. Loudspeaker driver efficiency is typically measured on a standard IEC 135cm x 165cm baffle for drivers with a diameter of 8" or less.  Drivers measured in this baffle will have maximum upper bass support from the wide baffle, with virtually no baffle step.  However, the deep bass and mid bass will suffer due to the out phase bass wave, and the bass efficiency will measure lower than if it were in a properly designed enclosure.

Loudspeaker efficiency includes the effects of the speaker cabinet.  In most domestic speakers this means that we have less upper bass reinforcement because of the relatively narrow (<12") baffle and greater deep to midbass reinforcement due to the cabinet capturing and/or reinforcing the rear wave.

Louis's OEM driver efficiencies and loudspeaker efficiencies are identical.  The only anomaly is the Alnico driver is listed as 93dB while the single driver Alnico models are listed as 95dB.  I can only assume this is an artifact of the website update.  He had previously listed both the driver and the speakers as 93dB.

We can also look at the RS7 driver, which Louis lists as 95dB as he does for the RS7-based loudspeakers.  However, Charney Audio uses this same driver in a back loaded horn (the Maestro) and lists the efficiency at 103dB.  This defies logic until we take into account measured bandwidth and deviation from a nominal efficiency, which leads us to...

Frequency Response and Deviation from Nominal Efficiency

While "20hz to 20khz" is a frequently cited standard for audio frequency response, it is nominal at best and simply describes the best case for human hearing.  When we begin to talk about loudspeakers, we need to talk about two things:  frequency response - the lowest to highest frequencies that the speaker is capable of reproducing and deviation from the nominal efficiency - how loudly or softly a particular frequency is reproduced.  Without this latter specification, the frequency response specification is all but meaningless.  Even a supertweeter can reproduce the lower bass notes, but at such a low level as to be useless.

Frequency response is typically expressed as a frequency band, e.g., 40hz - 18,000hz, +/- 3dB.  That simply means that when fed pink noise within this stated frequency range, the will stay within a range of 6dB.  That also means the speaker make be reproducing 90dB at 40hz and 96dB at 1,000hz.  This is not uncommon with single driver speakers.

So what about the 103dB Charney Maestro?  Louis uses the RS7 driver in 95dB speaker that sounds reasonably balanced in a stated frequency response of 45-20,000hz (no deviation stated).  So how does this same driver produce 103dB in a back loaded horn?  Three possibilities come to mind:

1.  The measured frequency range is restricted.  They may be measuring frequency response from 300-12,000hz.
2.  The response deviation band may be very wide.  if the band is +/- 6dB, the frequency efficiency may range from 91dB to 103dB.
3.  The manufacturer is not presenting a completely accurate efficiency spec.

In all likelihood, it is a combination of all three in this case.  If Louis' speaker was balance in a bass reflex alignment, and the Charney speaker achieved a peak of 103dB somewhere in the midband, we can reasonably assume the highs to be relatively less sparkly.

Anechoic Response vs. In-Room Response

It is typical to measure loudspeakers in an anechoic environment that attempts to remove the effect of the room on loudspeaker performance.  However, that rarely describes our own listening environment.  Most of us have relatively small listening rooms, often shared with other household uses and decorated with furnishings and finishes that are often less than acoustically optimal.  It is more important that a loudspeakers frequency response and/or efficiency be stated as it lives in this environment.  In fact, there are a number of manufacturers (I'm looking at you Audionote) that state the frequency response of their loudspeakers when properly placed in the room

Concluding Thoughts

I have not measured any of the Omega speakers I own, not as raw drivers nor as speaker systems.  Louis provides a nominal efficiency and frequency response specification for his speakers with no stated deviation.  I don't have a problem with that, as I listening to the speakers rather than measuring them.  Some people may get bent out of shape by the absence of a +/- 3dB number, but that spec is again nominal in nature.  I doubt I could tell if a frequency is 3dB down or 5dB down simply by listening to it using music in my listening room.  I would also argue that the response that one user gets will differ significantly than another user depending on room and the amplifier used.








EVOLVIST

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Re: Omega Speaker Efficiency
« Reply #1 on: 17 Feb 2017, 10:34 pm »
Thank you for writing this up. It's a really cool read. Moreover, it shows me that in my quest to understand speakers (and all the terminology that goes with them), that there are few absolutes.

I ordered some CAMs, though, and they are about a month out, so I'm really looking forward to this new journey, me, the guy who has been strictly headphones since about 1983.

So, is there anyway to tell how many db the CAMs are pushing at 2w if you're feeding it 2w, without an SPL meter?

I have to admit that I'm still a little nervous that even with nearfield listening, between 3ft and 6ft away, that delivering between 2vRMS and 6.7vRMS would underpower a set of CAMs, despite everyone telling me I shouldn't have anything to worry about other than I might want to add a sub.

roscoe65

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Re: Omega Speaker Efficiency
« Reply #2 on: 18 Feb 2017, 01:06 am »
Thank you for writing this up. It's a really cool read. Moreover, it shows me that in my quest to understand speakers (and all the terminology that goes with them), that there are few absolutes.

I ordered some CAMs, though, and they are about a month out, so I'm really looking forward to this new journey, me, the guy who has been strictly headphones since about 1983.

So, is there anyway to tell how many db the CAMs are pushing at 2w if you're feeding it 2w, without an SPL meter?

I have to admit that I'm still a little nervous that even with nearfield listening, between 3ft and 6ft away, that delivering between 2vRMS and 6.7vRMS would underpower a set of CAMs, despite everyone telling me I shouldn't have anything to worry about other than I might want to add a sub.

Short answer:  No, because you are relying on stated specifications from the manufacturer under different conditions than you may experience.  However, we all have smartphones and free or cheap RTA apps will allow us to pretty accurately measure the SPL and frequency response, especially with a calibrated microphone like this one:  http://www.parts-express.com/dayton-audio-imm-6-calibrated-measurement-microphone-for-tablets-iphone-ipad-and-android--390-810.

If you don't want to measure at all and are willing to rely on simple arithmetic (or cheat and plug the numbers into Wolfram Alpha), you can determine SPL levels.  The CAM's are rated at 95/dB/w/m.  That means at one meter (39.6 inches - slightly more than 3 feet) each speaker will put out 95dB when fed one watt.  You're listening in stereo, so that means you have twice as much acoustic power.  Doubling the power adds 3dB, so at one meter you'll get 98dB with one watt.  With two watts, you'll add another 3dB for a total of 101dB.  That's pretty freaking loud by anyone's standards.

If your listening distance is two meters instead of one meter, the SPL will be lower.  Since we are a point source radiating into free space, the SPL falls off in an inverse square of the distance.  If we double the distance from one meter to two meters, the SPL will be 1/(2 x 2), or 1/4 the SPL.  So instead of losing 3 dB by doubling the distance, we lose 6 dB.  Our 101dB is now 95dB, which is still plenty loud.

That still doesn't tell you how loud the speaker "feels".  In your case the CAM may produce 95dB but not over the entire frequency range that you need to find it musically satisfying.  The CAM appears to be designed to benefit from room boundary reinforcement.  This is especially important if you listen at relatively low levels (such as quietly at night).  Because our ears are much more sensitive to the midband than low and high frequencies, a speaker that is bass-light might find especially thin at low levels.  Older receivers used to have a "Loudness" switch that boosted low and high frequencies to compensate for this as low volumes.  If you listen primarily to digital sources you may accomplish something similar (or superior) using DSP.

As far as 2W being sufficient for a pair of CAM's, there are those of us running 4W amps into the alnico drivers and Canada Rob (among others) has expressed great satisfaction with a 2W Decware Super Zen running SAM's.




piezoman

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Re: Omega Speaker Efficiency
« Reply #3 on: 24 Apr 2020, 07:22 pm »
roscoe,

"....Louis's OEM driver efficiencies and loudspeaker efficiencies are identical.  The only anomaly is the Alnico driver is listed as 93dB while the single driver Alnico models are listed as 95dB.  I can only assume this is an artifact of the website update.  He had previously listed both the driver and the speakers as 93dB...."

I just received a custom pair of Junior XRS with the ALNICO driver. On the back of the speakers, he states they are rated at 95dB.

RDavidson

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Re: Omega Speaker Efficiency
« Reply #4 on: 24 Apr 2020, 08:42 pm »
I think Louis is figuring output reinforcement from the front baffle of the speakers (i.e. baffle step) versus the drivers in free space, hence the 95db spec of the constructed speaker versus 93db for the driver alone.

roscoe65

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Re: Omega Speaker Efficiency
« Reply #5 on: 24 Apr 2020, 11:01 pm »
In much broader terms efficiency needs to be expressed in terms of bandwidth and resolution.  I know that Altec specified frequency (e.g. 500-3000hz).  We would expect to see reasonable resolution, such as +/- 3dB.  I’m not saying Louis is incorrect, but my Super 3 Monitors with RS5 driver are rated as 94.5(!) dB/w/m.  I am sure that number is accurate for some portion of the audio spectrum, but there is no way you can tell me this speaker is doing 94.5 (+/- 0.25dB?) from 60hz to >15khz.  My ears tell me otherwise, especially when I compared the speakers side-by-side with Super Alnico monitors.  To my ears, these drivers were pretty much the same efficiency from the mid band up, with the RS5 reaching a bit higher, or at least giving that impression.  From the upper bass down, the smaller driver sounds considerably thinner, and I would estimate the midbass to be down at least 3-5 dB.

This is borne out in my experience with my Super 3HO monitors:  the second driver is only active from 500hz down, adding an additional 3dB output from the upper bass and below.  The balance of this speaker when driven by a tube amp is much fuller than the single driver model and is similar to the 6” Alnico driver.  Speaking of tube amps...

Efficiency of the Super 3HO Monitor speakers:

This “1.5 way” speaker comprises two identical RS5 drivers in parallel.  The lower helper driver has a single inductor in series for a 6dB low pass filter at 500hz.  The total surface area below 500hz is about the same as a single 6” driver.  The speaker is rated 97.5 dB efficiency.  I do not agree with this rating.

The single driver speaker is rated at 94.5dB.  The dual driver speaker is rated 3dB higher as we would expect by doubling the driver count.  However, the second driver is only active below 500hz.  From 500hz up there is only one driver playing, just as in the single driver speaker, producing 94.5dB.  Below 500hz, the second driver comes in at 6dB/octave, adding 3dB in the midbass when driven by a tube amp.

However, if we drive the speakers with a typical solid state amp that doubles in power when we halve the impedance, we have a problem.  The second driver in parallel below 500hz will not only double the acoustic power of the speaker for a given voltage, it will draw twice as much power from the amplifier.  Driven by a SS amp, the second driver adds 6dB to the midbass rather than the 3dB added using a tube amp.  The resulting sound is an overblown midbass that muddies the sound.

So how efficient are these speakers?

Based on memory and only my own ears, my seat of the pants opinion is:

1.  Super 3 Monitor, single RS5 driver, wide baffle:  This speaker started out as a 93dB Fostex model.  It now features the 94.5dB RS5 driver.  I would estimate that this is a 92-94 dB speaker from 150-15khz.  The wide baffle helps in the lower midrange and upper bass.  Corner or near wall placement really fleshes out the midbass and balances out the sound.  Played in a small room with a small SET (I use a 4wpc 421A amp) this thing punches way above its weight.  Ideal power is 3-5wpc.  the driver can’t really use more than that and sounds compressed if you try to make it do more than it can.  The tonal balance of this speaker reminds me of a higher-resolution Spica TC-50, with the lack of deep bass balanced by a slightly forgiving top end.  I have these on Skylan 24” stands, but in my opinion the XRS version of this speaker may be the best all-around small room speaker Louis has ever made.

2.  Super Alnico Monitor:  I no longer own these as I have too many projects and couldn’t justify a largish Alnico monitor.  I already had some Altec based 12” speakers so I needed to thin the herd (this was before the CAM came out).  this speaker is now rated 95dB whereas the same speaker was previously rated at 93dB.  My ears tell me this is again about a 92-94dB speaker, this time from probably 60hz -15khz.  I had the SAM’s on 20” Skylan stands near corners.  They could easily play four times as loud as the smaller speaker, with a much fuller midbass and ability to take more power.  The RS5 driver has a better high end hands down.  It extends higher and doesn’t have some of the challenges posed by the whizzer cone of the Alnico driver.

3.  Super 3 HO Monitor:  These are currently in my larger room, joined by a pair of Rhythmik F8 subwoofers.  It is a powerful combo driven by 5-30wpc.  As I stated before, I believe the dual driver speaker to be the same 92-94dB efficiency as the single driver model, but this time from 60-15khz.  The second driver below 500hz really balances the speaker.  It also allows it to play considerably louder than the single RS5 speaker as it can now absorb twice the power in the bass.  I also found them to be able to more comfortably play louder than the SAM.

I listened to these speakers using one SS amp (Red Wine Audio Signature 16), an Oliver Sayes-built FI 421A, and two Dennis Has Inspire SEP amps (one of which as been on long-term loan to Louis for so long I am afraid to ask for it back).  All amps were run from the 8 ohm tap of the 421A, and the single (6 ohm) tap of the Inspire amps (which as rated for full power at 2-20 ohms).  In general, these speakers, even the dual driver model, are very easy to drive.  Their impedance are benign and they have no (or very simple) crossovers.  None of the speakers drew more or less power from the amps due to impedance.

What do these speakers do best?

1.  Super 3 Monitor.  Great small room speaker, fantastic on vocals.  Will not really get down a boogie unless you relive them of the deepest notes.  If you could high-pass before the amp at about 100hz and add subwoofers you could really cut loose.

2.  SAM.  If I were buying this speaker again I would buy the CAM or the Junior 6 (AKA Super Six XRS).  These are a better naturally balanced speaker than the smaller RS5 speaker, can play a lot louder and work in larger rooms, but if you are looking for something to raise the roof you will still be disappointed.  They do have a seductive wetness about them that is intoxicating, but do have their limitations.  I couldn’t make these work for me, but they are a fantastic all-around grown-up speaker that will competently showcase much more expensive upstream equipment.  They do require some care in system matching and setup to optimize bass.

3.  Super 3 HO.  Beautiful proportions (I have quartered ebony) and great balanced sound.  At first glance they are a great high-efficiency replacement for speakers like the Harbeth P3 or KEF LS50.  However, while they fill this high-resolution monitor role, they do require tube power (or careful matched SS, such as Pass or Firstwatt current amps that do not double into halved impedance) to sound acceptable.  They can best run on 5-50 tube wpc, though a 45 SET would probably do ok at lower levels.  They mostly sound like a bigger, more powerful Super 3 single driver speaker.  Mostly.  To my ears they do give up a small amount of the single driver magic.  The two drivers in the larger speaker are 90 degrees out of phase (and about 6” apart in vertical displacement) so will likely only be completely coherent at a single point from the speaker at a single frequency.  This is a far cry from the phase anomalies and driver spacing on conventional multi-driver speakers but to my ears makes the speaker very slightly less coherent than the single driver model.  The balance of the single driver speaker features more forward (i.e., less balanced) midrange that gives female vocals a magical presence.

All of these speakers are special but all require careful system matching.  Ironically, the amp that was the most universally successful with all the speakers was the Sayes/Fi 421A.  4.5 wpc is plenty with these speakers in my room.  The amp is very high resolution and the 421A tube produces great bass.  This is helped by the oversized Hashimoto output transformers.  The Inspire amps (a KT88 HO at 12wpc and a PSE with 10-24 wpc depending on output tube) both had at least twice the power but couldn’t match the bass of the 421A.  Admittedly Dennis used smaller custom outputs on his amps, but the 421A is really something special.




AvsFan

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Re: Omega Speaker Efficiency
« Reply #6 on: 25 Apr 2020, 12:44 am »
In much broader terms efficiency needs to be expressed in terms of bandwidth and resolution.  I know that Altec specified frequency (e.g. 500-3000hz).  We would expect to see reasonable resolution, such as +/- 3dB.  I’m not saying Louis is incorrect, but my Super 3 Monitors with RS5 driver are rated as 94.5(!) dB/w/m.  I am sure that number is accurate for some portion of the audio spectrum, but there is no way you can tell me this speaker is doing 94.5 (+/- 0.25dB?) from 60hz to >15khz.  My ears tell me otherwise, especially when I compared the speakers side-by-side with Super Alnico monitors.  To my ears, these drivers were pretty much the same efficiency from the mid band up, with the RS5 reaching a bit higher, or at least giving that impression.  From the upper bass down, the smaller driver sounds considerably thinner, and I would estimate the midbass to be down at least 3-5 dB.

This is borne out in my experience with my Super 3HO monitors:  the second driver is only active from 500hz down, adding an additional 3dB output from the upper bass and below.  The balance of this speaker when driven by a tube amp is much fuller than the single driver model and is similar to the 6” Alnico driver.  Speaking of tube amps...

Efficiency of the Super 3HO Monitor speakers:

This “1.5 way” speaker comprises two identical RS5 drivers in parallel.  The lower helper driver has a single inductor in series for a 6dB low pass filter at 500hz.  The total surface area below 500hz is about the same as a single 6” driver.  The speaker is rated 97.5 dB efficiency.  I do not agree with this rating.

The single driver speaker is rated at 94.5dB.  The dual driver speaker is rated 3dB higher as we would expect by doubling the driver count.  However, the second driver is only active below 500hz.  From 500hz up there is only one driver playing, just as in the single driver speaker, producing 94.5dB.  Below 500hz, the second driver comes in at 6dB/octave, adding 3dB in the midbass when driven by a tube amp.

However, if we drive the speakers with a typical solid state amp that doubles in power when we halve the impedance, we have a problem.  The second driver in parallel below 500hz will not only double the acoustic power of the speaker for a given voltage, it will draw twice as much power from the amplifier.  Driven by a SS amp, the second driver adds 6dB to the midbass rather than the 3dB added using a tube amp.  The resulting sound is an overblown midbass that muddies the sound.

So how efficient are these speakers?

Based on memory and only my own ears, my seat of the pants opinion is:

1.  Super 3 Monitor, single RS5 driver, wide baffle:  This speaker started out as a 93dB Fostex model.  It now features the 94.5dB RS5 driver.  I would estimate that this is a 92-94 dB speaker from 150-15khz.  The wide baffle helps in the lower midrange and upper bass.  Corner or near wall placement really fleshes out the midbass and balances out the sound.  Played in a small room with a small SET (I use a 4wpc 421A amp) this thing punches way above its weight.  Ideal power is 3-5wpc.  the driver can’t really use more than that and sounds compressed if you try to make it do more than it can.  The tonal balance of this speaker reminds me of a higher-resolution Spica TC-50, with the lack of deep bass balanced by a slightly forgiving top end.  I have these on Skylan 24” stands, but in my opinion the XRS version of this speaker may be the best all-around small room speaker Louis has ever made.

2.  Super Alnico Monitor:  I no longer own these as I have too many projects and couldn’t justify a largish Alnico monitor.  I already had some Altec based 12” speakers so I needed to thin the herd (this was before the CAM came out).  this speaker is now rated 95dB whereas the same speaker was previously rated at 93dB.  My ears tell me this is again about a 92-94dB speaker, this time from probably 60hz -15khz.  I had the SAM’s on 20” Skylan stands near corners.  They could easily play four times as loud as the smaller speaker, with a much fuller midbass and ability to take more power.  The RS5 driver has a better high end hands down.  It extends higher and doesn’t have some of the challenges posed by the whizzer cone of the Alnico driver.

3.  Super 3 HO Monitor:  These are currently in my larger room, joined by a pair of Rhythmik F8 subwoofers.  It is a powerful combo driven by 5-30wpc.  As I stated before, I believe the dual driver speaker to be the same 92-94dB efficiency as the single driver model, but this time from 60-15khz.  The second driver below 500hz really balances the speaker.  It also allows it to play considerably louder than the single RS5 speaker as it can now absorb twice the power in the bass.  I also found them to be able to more comfortably play louder than the SAM.

I listened to these speakers using one SS amp (Red Wine Audio Signature 16), an Oliver Sayes-built FI 421A, and two Dennis Has Inspire SEP amps (one of which as been on long-term loan to Louis for so long I am afraid to ask for it back).  All amps were run from the 8 ohm tap of the 421A, and the single (6 ohm) tap of the Inspire amps (which as rated for full power at 2-20 ohms).  In general, these speakers, even the dual driver model, are very easy to drive.  Their impedance are benign and they have no (or very simple) crossovers.  None of the speakers drew more or less power from the amps due to impedance.

What do these speakers do best?

1.  Super 3 Monitor.  Great small room speaker, fantastic on vocals.  Will not really get down a boogie unless you relive them of the deepest notes.  If you could high-pass before the amp at about 100hz and add subwoofers you could really cut loose.

2.  SAM.  If I were buying this speaker again I would buy the CAM or the Junior 6 (AKA Super Six XRS).  These are a better naturally balanced speaker than the smaller RS5 speaker, can play a lot louder and work in larger rooms, but if you are looking for something to raise the roof you will still be disappointed.  They do have a seductive wetness about them that is intoxicating, but do have their limitations.  I couldn’t make these work for me, but they are a fantastic all-around grown-up speaker that will competently showcase much more expensive upstream equipment.  They do require some care in system matching and setup to optimize bass.

3.  Super 3 HO.  Beautiful proportions (I have quartered ebony) and great balanced sound.  At first glance they are a great high-efficiency replacement for speakers like the Harbeth P3 or KEF LS50.  However, while they fill this high-resolution monitor role, they do require tube power (or careful matched SS, such as Pass or Firstwatt current amps that do not double into halved impedance) to sound acceptable.  They can best run on 5-50 tube wpc, though a 45 SET would probably do ok at lower levels.  They mostly sound like a bigger, more powerful Super 3 single driver speaker.  Mostly.  To my ears they do give up a small amount of the single driver magic.  The two drivers in the larger speaker are 90 degrees out of phase (and about 6” apart in vertical displacement) so will likely only be completely coherent at a single point from the speaker at a single frequency.  This is a far cry from the phase anomalies and driver spacing on conventional multi-driver speakers but to my ears makes the speaker very slightly less coherent than the single driver model.  The balance of the single driver speaker features more forward (i.e., less balanced) midrange that gives female vocals a magical presence.

All of these speakers are special but all require careful system matching.  Ironically, the amp that was the most universally successful with all the speakers was the Sayes/Fi 421A.  4.5 wpc is plenty with these speakers in my room.  The amp is very high resolution and the 421A tube produces great bass.  This is helped by the oversized Hashimoto output transformers.  The Inspire amps (a KT88 HO at 12wpc and a PSE with 10-24 wpc depending on output tube) both had at least twice the power but couldn’t match the bass of the 421A.  Admittedly Dennis used smaller custom outputs on his amps, but the 421A is really something special.

Roscoe65,

THANK you SO VERY much for the time it took to put all your thoughts down on the different speakers. Sincerely! This is one of the best and most informative posts I have ever read on any thread on any forum. Very in depth. Thank you! It's helped me out a ton with choosing an amp for my new Super 3 HO's. I have been in talks with Alan Eaton on building me a 45 SET. Seems like it might be a good match.

Brad

Re: Omega Speaker Efficiency
« Reply #7 on: 25 Apr 2020, 02:54 am »
I'm driving Super 3is with a Korneff 45 amp and have had no issues with volume, albeit in a relatively small room, 10x11.
I did add an 8" powered sub to fill in the low end a bit.

We've actually been listening to blues on them all night tonight from the next room away.   8)

Great match, really good detail and lovely tone.

AvsFan

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Re: Omega Speaker Efficiency
« Reply #8 on: 25 Apr 2020, 04:10 am »
I'm driving Super 3is with a Korneff 45 amp and have had no issues with volume, albeit in a relatively small room, 10x11.
I did add an 8" powered sub to fill in the low end a bit.

We've actually been listening to blues on them all night tonight from the next room away.   8)

Great match, really good detail and lovely tone.

That’s VERY good news. My room is 12x10. And I am adding two 8inch subs. So should get a very similar experience. I’m looking forward to them!

roscoe65

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Re: Omega Speaker Efficiency
« Reply #9 on: 25 Apr 2020, 12:31 pm »
I will add my other experience with small room/small amps:

Like others in this forum, I’ve been at this for a while.  I’ve been in this hobby since 1985 and first got into SET’s and high efficiency speakers in 1993.  In those early days I owned a 45 SET amp built by Gary Dahl of the Oregon Triode Society.  It was a direct-coupled amp (I believe from a Sound Practices design) using all Magnequest iron.  I drove it with an Audible Illusions 2D and drove a pair of custom 8” grow-ways:  Cabasse 21M18 8” woofers and Dom 2 tweeters, about 90-94 dB efficient.  I handmade solid silver speaker wire using PTFE shrink tubing.  This combination is to this day the best sound I have personally achieved.  It had its limitations in bass and ultimate output.  I had the speakers on the floor tilted up like a pair of old JBL’s.  This system was intimate, lively, and had a wet, organic quality that was intoxicating.  Regretfully, I sold off the equipment as I spent the next two decades trading and trying to “improve” things as the SET world grew larger.

Some other thoughts regarding efficiency, Omega speakers, and a 10’ x 12’ room:

1.  Don’t rely on the arithmetic to determine whether something will work for you.  I’ve had a number of combinations that shouldn’t work but did.  I remember hooking a pair of Dynaco A25XL speakers to a 6wpc Tripath amps and being blown away at the synergy.  Note that Louis did a custom modern version of this speaker for a customer using a sealed floor standing enclosure.

2.  Don’t expect any amp, speaker, or amp/speaker combination to to everything you want.  Prioritize based on how it makes the music you like to listen to sound good, not based on how you think the system should sound.  The Omega speakers are very revealing, unflattering tools.  They can sound beautiful but really benefit from careful system matching.  There is also nothing wrong with

3.  If your speakers are relatively lightweight, they can live in positions near the wall where they still sound good but not optimal.  They may be a easily moved our into the room for critical listening.  If you are like me, you share your space with your SO and like to enjoy music in background as well.  I like to have music where I am living and enjoying my life, not just in my private listening space.

4.  I’ve found that the ideal subwoofers to match with the RS5 drivers have lightweight, 8” paper drivers.  I’ve tried the 8” Peerless drivers used in the bucket subs and currently use Rythmik F8 dual 8” servo subs.  Rhythmik sells kit versions as well and Louis has built custom subwoofers using these kits.  In my opinion it is the ideal bass solution for Omega speakers.  Jim Salk used a Similar approach in his Exotica 3 speakers.

5.  The 1.5-way HO models are not the first dual driver Omega speakers Louis has made.  Also made dipole/bipolar models and an omnidirectional model.  The latter is interesting in that the second driver is run full range but point upward toward the ceiling.  Frequencies above the midbass fall off very rapidly off-axis (we’re talking 10-30dB down) while the upper frequencies increase the upper frequency power into the room and provide ceiling splash.  This is in line with some thoughts by Duke at Audiokinesis with his Late Ceiling Splash setup and Danny at GR Research in his thoughts about adding upward-facing super tweeters to full range drivers.  This arrangement can be replicated in the Omega world by ordering an Omni model or alternatively using two speakers, one firing upward.  Through some horse-trading I have ended up with an extra pair of RS5 drivers.  I also have a pair of Ebay Fostex Fe126e cabinets that should work for testing purposes.  When time and creativity permit, I will test out a near-field setup using RS5 speakers in a Late Ceiling Splash arrangement.

6.  Treat your room.  My advice is to reach out to GIK and ask for their recommendations.  The advice is free, the products are top notch, and the people are great.

7. The single best thing you can do is to commit to near-field listening.  With a small room you need to take as much of the room out of the equation as you can.  My Omega Super 3 monitors on stands can be moved to a point on either side of my listening chair, forming a three-foot equilateral triangle.  In this position they start behaving a bit like headphones, in a good way.  Unlike headphones the speakers will provide a visceral effect, increasing the perceived musical power.  This is combined with a subwoofer (or 2 or more) to provide the bass foundation and visceral weight.  A key is to run the monitors full-range to help localize bass.  In this configuration, you probably can hit 100 dB peaks with a 45 SET and a pair of single-driver Omega speakers.  Compare this with a high end headphone rig like a Woo Audio 5998 amp and AKG K1000’s.  There is a bit of convergence in personal listening:  We can use smaller speakers with a very low power speaker amp or very power-hungry headphones with a very high power headphone amp.  These small speakers like my Super 3’s can have small, 4” single drivers.  Coincidently, this is the same size as some high end headphones.

Do a search for posts by user Guf; he has been exploring near field setups with a number of Omega speakers and shares some of my opinions.

guf

Re: Omega Speaker Efficiency
« Reply #10 on: 25 Apr 2020, 03:00 pm »
LOL i read this whole post thinking I dont need to share my input because Roscoe65 is speaking my language. :) 

My experience is very similar to his, maybe becuase I often follow his suggestions. Although I'm down to 1 pair of Omega speakers, ( i follow ths same principles with all my speakers), near field, low power, and i use powered subs.  I do things that shouldn't work and they do to me. 

AvsFan

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Re: Omega Speaker Efficiency
« Reply #11 on: 25 Apr 2020, 03:16 pm »
LOL i read this whole post thinking I dont need to share my input because Roscoe65 is speaking my language. :) 

My experience is very similar to his, maybe becuase I often follow his suggestions. Although I'm down to 1 pair of Omega speakers, ( i follow ths same principles with all my speakers), near field, low power, and i use powered subs.  I do things that shouldn't work and they do to me.

And like I posted earlier. Roscoe’s words of wisdom are some of the most informative and meaningful posts I have read.

This is exactly how I am configuring my room. Low power and near field. Probably no more than 4 feet. Dual 8 inch driver subs. So a total of 4 8’s. They will be Louis’s. So a perfect match. This will be my “audiophile” system. A system that I will play all genres of music on but within reason and it’s limits. If I truly want ear bleed concert level music, I will use my ZU Audio system for that.

roscoe65

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Re: Omega Speaker Efficiency
« Reply #12 on: 25 Apr 2020, 04:54 pm »
LOL i read this whole post thinking I dont need to share my input because Roscoe65 is speaking my language. :) 

My experience is very similar to his, maybe becuase I often follow his suggestions. Although I'm down to 1 pair of Omega speakers, ( i follow ths same principles with all my speakers), near field, low power, and i use powered subs.  I do things that shouldn't work and they do to me.

And I’ve followed your suggestions as well.  While I have a number of potential systems I can use, my current choices are Omega RS5 speakers and Altec 414/802/32A two-ways.  I have a number of amps, but my favorite remains my Olive Sayes [Fi] 421A.  I could easily live with that amp and the single driver Super 3 speakers and not feel I am missing anything in the right context.  Add a couple of subwoofers and I don’t think I would miss a thing.  The amp, speakers and stands were less than $2,000 total to me.  I would not be embarassed to pair this combo with jus about any front end.

roscoe65

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Re: Omega Speaker Efficiency
« Reply #13 on: 26 Apr 2020, 12:12 am »
And I’ve followed your suggestions as well.  While I have a number of potential systems I can use, my current choices are Omega RS5 speakers and Altec 414/802/32A two-ways.  I have a number of amps, but my favorite remains my Olive Sayes [Fi] 421A.  I could easily live with that amp and the single driver Super 3 speakers and not feel I am missing anything in the right context.  Add a couple of subwoofers and I don’t think I would miss a thing.  The amp, speakers and stands were less than $2,000 total to me.  I would not be embarassed to pair this combo with jus about any front end.

I’m not sure if you had mentioned your intended room setup, but with a 10’ x 12’ room you will be facing challenges.  If the room is dedicated, I would take these considerations:

1.  Near Field.  The nearer the better.  Ideally you want the sound to hit your ears before any other boundary.  I was serious when I said you should think about having the speakers two feet from your ears.

2.  If you can, your entire system (including yourself as the listener) should fit in the first third of the room, leaving the other two thirds behind you.  This will be very difficult in such a small room, which is why I recommend you...

3.  Try using the diagonal.  Not only does this change your longest dimension from 12 feet to 15.6 feet, it offers some real advantages.  If you face the corner with your head at the 1/3 position along the diagonal, you can now fit your entire setup in the front of the room without needing to have the speakers act as oversized headphones.  As an added advantage, the speakers are now firing straight out from the wall; you can place them closer to the wall while still pointing directly at your ears.  The additional space in front of your feet will add to the sense of depth, especially if you can add some diffraction there.

4.  I would use two subwoofers but consider that you may want to use them in mono.  You will likely need to move them around the room and adjust the volume and crossover points of each separately.  You may end up with one in the corner in front of you and one in the middle of a side wall.

5.  Expect to need bass traps and other room treatment.  Rather than go into specific recommendations I would recommend you spend some time with the folks at GIK or in their forum.  I would advise against overdamping the room.  I like to keep a little liveliness in the room.

6.  Think about super tweeters.  You are going to be putting a significant amount of energy into the room from the bass upward, but this will get directional as frequencies rise.  Adding an upward firing super tweeter will help balance the treble energy in the room and add air and depth of image.  Danny Richie wrote a great piece on adding super tweeters to full-range drivers over on the GR Research Circle.

Unfortunately what we now have resembles a one-person listening pod in a 10’ x 12’ room.  I’m sure it can be made domestically acceptable with some creative furniture arrangement.

piezoman

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Re: Omega Speaker Efficiency
« Reply #14 on: 3 May 2020, 07:02 pm »
roscoe,

great posts!

i am brand new here. i am following your advice, along with that of louis. i too have a 12x10 room.........in my case, about 80% dedicated to audio ["open" designed antique wood desk with computer is the only furniture other than a listening chair - a fabric recliner].

so i am 100% committed to near-field listening.

i'm ridding myself of a 5.5 foot tall cherry audio cabinet, solid on 3 sides with a glass door front; this is NOT good between speakers or even behind and in between, so i'm selling it and have purchased an open-aired 32" high 3 shelf audio shelving unit to stay out of the way.

i have contacted GIK Acoustics the other day, and provided photos and all the info they need to come up with a plan for me. i am taking a rather minimalist approach to room treatments, not 100% perfection.

speakers are omega junior 8 xrs cabinet with single 6" alnico driver. this was recommended by Louis for my room and listening habits. i started out by telling him i'm not a fan of monitors on stands and i never want to go that route. these cabinets have pretty small footprint in the room being just 35"H x 12"W x 7"D and are very easily placed/mobile.

my amp will be a decware 3 watt zen taboo mk 4, their lauded headphones + speaker amp. single-ended pentode. i will have the benefit of equalizing bass output via a decware ZRock2, which will help shape the bass and mid-upper frequencies.

i expect this system to be my end game, as i'm not into the insanity of the roller coaster of constant purchasing & selling while generally losing one's shirt every time those transactions are made. that is not fun, no matter what someone says!

best regards, brad

jmolsberg

Re: Omega Speaker Efficiency
« Reply #15 on: 3 May 2020, 07:33 pm »
^ that will be a beautiful sounding stereo Brad! Hard to beat at any price...

And great stuff roscoe!

piezoman

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Re: Omega Speaker Efficiency
« Reply #16 on: 3 May 2020, 08:02 pm »
thank you very much jmolsberg! your system must be superb.....and a real looker! 

and i'll bet those twin drivers are ultra fast and transparent.

woodnaudio

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Re: Omega Speaker Efficiency
« Reply #17 on: 4 May 2020, 03:35 am »
Brad, your setup, situation sounds a lot like mine. My room is only slightly larger (12x13) and also about 80% audio. I got my pair of Junior 8 XRS Alnicos early this year and have been running them with a 5 wpc Triode Lab EL84 integrated.

You won’t regret talking to GIK. I just put in a bunch of panels and corner traps from them and couldn’t be happier with the room sound now.

Enjoy, and welcome to the forum!

piezoman

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Re: Omega Speaker Efficiency
« Reply #18 on: 5 May 2020, 01:35 am »
Thank you wood! Indeed, we are similar. I gave them a pretty small budget, just $500. Im looking to address just the worst of the nasties....not perfection because that will only be cost prohibitive....just a couple base traps and a couple panels or so. Im curious to find out if both diffuser and absorber panels will be recommended.

woodnaudio

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Re: Omega Speaker Efficiency
« Reply #19 on: 6 May 2020, 08:08 pm »
Thank you wood! Indeed, we are similar. I gave them a pretty small budget, just $500. Im looking to address just the worst of the nasties....not perfection because that will only be cost prohibitive....just a couple base traps and a couple panels or so. Im curious to find out if both diffuser and absorber panels will be recommended.

When I talked to them, they said on a tight budget in a small room, it's all about getting as much absorption in as you can. The only diffusion they suggested was getting scatter plates put in the tri-traps (or using CT alphas with the scatter plates on front)