My Finally Beautiful Digital Sound post from March 2014 created a lot of interest and still gets quite a few visits.
These days I'm often asked what I'm using for digital in 2016 and I'm pleased to say I'm still using the "old" Philips TDA1541 R2R dac chip.
I still haven't heard a modern dac chip that gives the same ease and musicality - the new delta sigma chips are much better than the earlier ones, but still don't quite give that overall fatique free listening experience the olde R2R dac chips like the 1541, PCM1702, 1704 etc.
I'm using state of the art FIFO buffering and USB to I2S direct into the 1541. This enables play of hi-res up to 384Khz . So its a combination of the old and new digital process's.
I also use a no-usb approach , which is also FIFO based , and I2S direct . IMO this sounds even more natural and organic than the USB approach, although the difference is not startling, just again a more relaxing, emotive and musical sound.
Over the last few years DSD has gained some traction in the audiophile world. Every new dac seems to be DSD capable , and I've spent a fair bit of time playing around with DSD dacs and DSD implementation.
Make no mistake, DSD can sound very good .
But at its essence , any method, whether its the PCM derivatives - MP3, FLac, AIFF, etc or DSD, SACD, DXD etc are only as good as the original recording .
A good sounding DSD , just like PCM , requires a very good recording technique and equipment , if its a poor recording being DSD wont "fix" it or sound any better.
A very well recorded MP3 file will sound far better than any mediocre DSD recording .
Another method gaining some popularity is up-sampling PCM to DSD 512 or higher. Again, this can sound very good, but is also dependent on the quality of the original recording .
And this method requires heavy computer power and an almost obsessive dedication to going to all the trouble of doing this.
I did it for a while, but then came to realize I was missing the basis of why I enjoy fooling around with all this- the enjoyment and satisfaction of listening to music.
And it all comes down to the quality of the original recording, so isn't it just as meaningful to concentrate on what really makes a difference rather than concentrating on the small differences between playback methods, whether PCM or DSD etc.
I think its vitally important to get a speaker and system that really appeals and talks to you.
It should be so good that you would consider it a lifetime choice if needed .
Speakers and preamps count far, far, more in your system than any dac, and have so much more effect to give you the music that you want to listen to.
Get the basics of your system right, find the speaker you can listen to, and enjoy all day long.
When you have that right you will enjoy listening to music and not fretting about whether your missing out on the latest dac of the month.
Monday, October 31, 2016
Monday, October 10, 2016
Eminence Alpha/ Supravox 215-EC/RAAL 70-20XR Pt 3
I used Dirac Live with calibrated mic to measure the 215/Eminence combination and this is the result.
It looks a bit bumpy, but this isn't actually too bad. It's a result of speaker and room.
The Eminence bass level is higher than the Supravox , but I've deliberately set it like this .
I also tried moving the bass crossover frequency up higher, but sonically it sounds best like this.
You can see the 215 rolls off from about 5Khz, it doesn't sound as bad as it looks, indeed I didn't think it needed a tweeter, till I heard one in place.
The orange line is the target for correction , and Dirac does a pretty good job of getting very close to the target. It cant compensate for the roll-off above 5Khz , but it follows the target to there.
But it does show that for true full range a tweeter is needed. The problem is finding a high efficiency tweeter to match the Supravox.
I've used ribbon tweeters before, with limited success, they can be thin and metallic sounding , however I've heard very good things about the RAAL ribbon tweeters, some claiming they sound unlike any other ribbon.
I ordered a pair of the 70-20XR from Russel Story at Stones Sound Studio and installed them alongside the Supravox.
Well, the claims were valid, these are the best sounding ribbons I've heard and match the 215's wonderfully well. They have quite amazing dynamics , seem completely unhindered and play as though they have much higher efficiency then their 92dB.
Detail is all there, but not in a metallic or tizzy way, its just open and realistic.
They don't sound as though a tweeter has been added, they combine effortlessly with the 215 to give a truly full range , organic and exciting sound.
I simply used a 3.6uF capacitor as passive crossover for the ribbon, and will experiment further with different values and adding an inductor.
Here is measurement of the complete 3 way of Eminence, Supravox and RAAL. Dont forget, this is speaker and room. A bit of juggling of levels and and the bass's DEQX EQ would get this even better, but I'm going to rely on Dirac to sort it out at this stage.
And here is the corrected response.
I've heard very expensive (>$20K)box speakers that cant do what this combination does.
Defined, tonally correct bass, the dynamic vividity of high efficiency near full range field coil , and the ribbon tweeter that sounds like it's not there, yet everything is so correct and beautiful.
And that is the perception of live , real music.
Next is to do a bit of fine tuning and put the drivers onto a nice furniture grade baffle.
It looks a bit bumpy, but this isn't actually too bad. It's a result of speaker and room.
The Eminence bass level is higher than the Supravox , but I've deliberately set it like this .
I also tried moving the bass crossover frequency up higher, but sonically it sounds best like this.
You can see the 215 rolls off from about 5Khz, it doesn't sound as bad as it looks, indeed I didn't think it needed a tweeter, till I heard one in place.
The orange line is the target for correction , and Dirac does a pretty good job of getting very close to the target. It cant compensate for the roll-off above 5Khz , but it follows the target to there.
But it does show that for true full range a tweeter is needed. The problem is finding a high efficiency tweeter to match the Supravox.
I've used ribbon tweeters before, with limited success, they can be thin and metallic sounding , however I've heard very good things about the RAAL ribbon tweeters, some claiming they sound unlike any other ribbon.
I ordered a pair of the 70-20XR from Russel Story at Stones Sound Studio and installed them alongside the Supravox.
Well, the claims were valid, these are the best sounding ribbons I've heard and match the 215's wonderfully well. They have quite amazing dynamics , seem completely unhindered and play as though they have much higher efficiency then their 92dB.
Detail is all there, but not in a metallic or tizzy way, its just open and realistic.
They don't sound as though a tweeter has been added, they combine effortlessly with the 215 to give a truly full range , organic and exciting sound.
I simply used a 3.6uF capacitor as passive crossover for the ribbon, and will experiment further with different values and adding an inductor.
Here is measurement of the complete 3 way of Eminence, Supravox and RAAL. Dont forget, this is speaker and room. A bit of juggling of levels and and the bass's DEQX EQ would get this even better, but I'm going to rely on Dirac to sort it out at this stage.
And here is the corrected response.
And here is the impulse- impressive!
I've had mixed results with Dirac, it doesn't always suit all types of speaker/room correction, sometimes the correction is worse than the problem, but here it has done a superb job with the Eminence/Supravox/RAAL combination.
Building this system is not in-expensive, but frankly I doubt you could get the same exciting , realistic and satisfying sound for many multiples of the cost.
I've heard very expensive (>$20K)box speakers that cant do what this combination does.
Defined, tonally correct bass, the dynamic vividity of high efficiency near full range field coil , and the ribbon tweeter that sounds like it's not there, yet everything is so correct and beautiful.
And that is the perception of live , real music.
Next is to do a bit of fine tuning and put the drivers onto a nice furniture grade baffle.
Saturday, October 8, 2016
Supravox 215-EC Field Coil Driver Pt 2
The first thing to do to get a field coil driver playing is to provide it with a power supply.
The 215-EC uses quite a lot of current - 5A at 12V. This requires a hefty power supply, and if regulation is used, then quite a large heatsink.
Another method is to use one of, or a pair of deep cycle 12V batteries.
With a trickle charger to keep the battery/s topped up, this a quite an effective solution and sounds very good.
However it takes up quite a lot of room space, is a bit ugly, and inconvenient.
I built 3 prototype power supplies , and chose to go with regulation using LT-1083 regulator chips , which are rated for 7.5A, 300VA 2x12V transformers and quite a substantial bank of capacitors for a stiff power supply. More heat-sinking than necessary so as to run cool and reliable.
The first PSU (power supply unit) used a pair of high current chokes to provide a very clean supply to the regulators. This is way over-kill and the next unit did away with the chokes, and no difference in sound quality was noted.
The next unit used a constant current regulator circuit, which provides constant current rather than constant voltage to the field coil.
In theory, this should be the least effective method, but over the long term, I quite liked the sound from the CCS.
The difference is very subtle, but it just sounds a bit smoother and easier to listen to.
I also settled on 10V operation , it seems to be a nice compromise between the more laid back 8V and the dynamic , but forceful 14 V operation.
Of course voltage selection will depend on the system the driver is used in. Open baffle is quite different to box operation and a quite different operating voltage could be required.
The Q's or parameters of the 215-EC are changed with different voltages so in reality they are quite different drivers at different voltages.
The drivers are mounted on a flat piece of plywood with solid pine bracing . I placed the 215 between two Eminence Alpha 15" bass drivers, which are designed for open baffle use. 215 is at ear level.
There is no crossover on 215, it is connected to a SE-300B power amp , which is driven by one of my DHT preamps.
The woofers are connected to tube monoblock amps, which are connected to DEQX unit, which is connected to same preamp.
Crossover in DEQX is 250Hz @ 24dB. this might seem a bit high, but in open baffle the 215 rolls off quite high and the Eminence has to be brought up to flatten the curve, as much as possible.
I also have some bass EQ to counter the eminence bass roll-off and give it a bit of oomph.
So how does it sound in this first, basic version?
Ive never been a fan of "box" speakers, the typical 2 or 3 way just doesn't provide enough excitement or realism for me. No matter how expensive or exotic, they always sound like a pair of speakers.
Planar speakers can also have their limitations, however the best do possess an ability to give a big wide sound that does come close to what you would actually hear in a studio or live entertainment venue.
Likewise with horns, the very best have a palpability that is to die for.
I'm not so much into impressive sound with explosive bass and scorching treble, I'd rather listen to something that has a natural musical tone and dynamics that simply sound real.
Music touches me when it gets close to revealing the emotion , ability and performance of the recording.
I don't want to listen to speakers, I want to listen to the recording.
The Supravox can do that, they do a very good job of disappearing and leaving the music in place.
Imaging, sound-staging are near perfect.
I haven't heard a speaker that can throw a big a sound as my modified Accoustat 2+2's , but at 8 foot tall and requiring 4 channels of 1000W , they are bordering on impractical for most situations.
The Supravox come very close and only require low power, preferably a tube power amplifier.
Like all full range drivers they are not monitor studio accurate, but they don't shout or have excessive peaks like Lowthers and the other full range drivers.
They are not perfect, but they are very interesting, and very satisfying drivers. You don't tire of the Supravox sound. Indeed its hard to turn them off!
Like a good tube preamp, they don't scream out their advantages, but take them away, and you soon miss them very much.
The integration with the Eminence bass drivers is good. Open baffle bass is a very interesting subject , and subjectively, very easy to listen too.
Open baffle cant do very low sub-bass, but what it can do is very articulate and defined bass. There is no boom or overhang . It may sound "light' if you are used to big subwoofers moving lots of air, but the definition is quite startling once you come to appreciate it.
If you have ever sat next to an acoustic bass you will have noticed there is no boom or lack of definition , you can clearly hear every note - open baffle bass is like that, the bass lines are very easy to follow and enjoy.
All in all a magnificent speaker system, but in Pt 3 I measure them, use digital speaker/room correction to make them damn near perfect, and use them with the amazing RAAL ribbon tweeter.
The 215-EC uses quite a lot of current - 5A at 12V. This requires a hefty power supply, and if regulation is used, then quite a large heatsink.
Another method is to use one of, or a pair of deep cycle 12V batteries.
With a trickle charger to keep the battery/s topped up, this a quite an effective solution and sounds very good.
However it takes up quite a lot of room space, is a bit ugly, and inconvenient.
I built 3 prototype power supplies , and chose to go with regulation using LT-1083 regulator chips , which are rated for 7.5A, 300VA 2x12V transformers and quite a substantial bank of capacitors for a stiff power supply. More heat-sinking than necessary so as to run cool and reliable.
The first PSU (power supply unit) used a pair of high current chokes to provide a very clean supply to the regulators. This is way over-kill and the next unit did away with the chokes, and no difference in sound quality was noted.
The next unit used a constant current regulator circuit, which provides constant current rather than constant voltage to the field coil.
In theory, this should be the least effective method, but over the long term, I quite liked the sound from the CCS.
The difference is very subtle, but it just sounds a bit smoother and easier to listen to.
I also settled on 10V operation , it seems to be a nice compromise between the more laid back 8V and the dynamic , but forceful 14 V operation.
Of course voltage selection will depend on the system the driver is used in. Open baffle is quite different to box operation and a quite different operating voltage could be required.
The Q's or parameters of the 215-EC are changed with different voltages so in reality they are quite different drivers at different voltages.
The drivers are mounted on a flat piece of plywood with solid pine bracing . I placed the 215 between two Eminence Alpha 15" bass drivers, which are designed for open baffle use. 215 is at ear level.
There is no crossover on 215, it is connected to a SE-300B power amp , which is driven by one of my DHT preamps.
The woofers are connected to tube monoblock amps, which are connected to DEQX unit, which is connected to same preamp.
Crossover in DEQX is 250Hz @ 24dB. this might seem a bit high, but in open baffle the 215 rolls off quite high and the Eminence has to be brought up to flatten the curve, as much as possible.
I also have some bass EQ to counter the eminence bass roll-off and give it a bit of oomph.
So how does it sound in this first, basic version?
Ive never been a fan of "box" speakers, the typical 2 or 3 way just doesn't provide enough excitement or realism for me. No matter how expensive or exotic, they always sound like a pair of speakers.
Planar speakers can also have their limitations, however the best do possess an ability to give a big wide sound that does come close to what you would actually hear in a studio or live entertainment venue.
Likewise with horns, the very best have a palpability that is to die for.
I'm not so much into impressive sound with explosive bass and scorching treble, I'd rather listen to something that has a natural musical tone and dynamics that simply sound real.
Music touches me when it gets close to revealing the emotion , ability and performance of the recording.
I don't want to listen to speakers, I want to listen to the recording.
The Supravox can do that, they do a very good job of disappearing and leaving the music in place.
Imaging, sound-staging are near perfect.
I haven't heard a speaker that can throw a big a sound as my modified Accoustat 2+2's , but at 8 foot tall and requiring 4 channels of 1000W , they are bordering on impractical for most situations.
The Supravox come very close and only require low power, preferably a tube power amplifier.
Like all full range drivers they are not monitor studio accurate, but they don't shout or have excessive peaks like Lowthers and the other full range drivers.
They are not perfect, but they are very interesting, and very satisfying drivers. You don't tire of the Supravox sound. Indeed its hard to turn them off!
Like a good tube preamp, they don't scream out their advantages, but take them away, and you soon miss them very much.
The integration with the Eminence bass drivers is good. Open baffle bass is a very interesting subject , and subjectively, very easy to listen too.
Open baffle cant do very low sub-bass, but what it can do is very articulate and defined bass. There is no boom or overhang . It may sound "light' if you are used to big subwoofers moving lots of air, but the definition is quite startling once you come to appreciate it.
If you have ever sat next to an acoustic bass you will have noticed there is no boom or lack of definition , you can clearly hear every note - open baffle bass is like that, the bass lines are very easy to follow and enjoy.
All in all a magnificent speaker system, but in Pt 3 I measure them, use digital speaker/room correction to make them damn near perfect, and use them with the amazing RAAL ribbon tweeter.
Monday, October 3, 2016
Supravox 215 Field Coil Driver. Pt1
Quite a while ago I read this on the 6moons website:
"After four years of building a number of different baffles, trying many drivers and fine-tuning passive crossover points, what conclusions have I arrived at? Only one. Anyone reading this can easily and for little cash build a substantially more open, palpable and real-sounding speaker system than they are likely living with at present regardless of cost."
That's a big claim, but the author seemed a genuine guy with some credibility, and I put it in the back of my mind to investigate further at a later date.
The author was describing an open baffle system, (no box, just a flat panel with drivers mounted on it) with field coil drivers.
Field coil drivers use an electro-magnet instead of a permanent magnet to generate the magnetic force to move the voice coil.
They require an external DC voltage to energise the electro-magnet. It's how the very earliest speakers were utilised, before permanent magnets were viable .
These days they are expensive and exotic, and one of the best designers and manufacturers is the French company Supravox.
Recently one of my preamp owners asked me to build him a power supply for his Supravox field coil drivers.
Its a little out of my field of expertise, but an interesting challenge.
Bob sent me a pair of Supravox 215-EC's to experiment with ( and then gave them to me- thanks Bob!)
The easiest way to get field coils going is with a car battery, the 215 are happy with 12V so a 12V deep cycle battery minimum 25 AH will last through an extended listening session.
After a warm up I was impressed enough to go further with open baffle and field coils.
I should mention that my friend Martin Seddon of Azura Horns has been using field coil drivers for some time now, specifically the Line Magnetic LM555W , which is a clone of the Western Electric 555 compression driver.
The realism of his system is extremely impressive , and initially piqued my interest in field coil drivers, hopefully I could pull the same palpable sound from the Supravox.
As you know, i'm a big fan of active speaker/amplification, ie using a seperate amplifier for each driver with either passive or active crossovers.
The Supravox is essentially full range , in the same vein as the Lowther , Coral, Feastrex full range drivers , but the Supravox doesn't have the shouty upper midrange accentuation of these drivers.
However these drivers are known for their dynamics and ease of portrayal of micro-dynamics, they are very revealing, but in an easy, almost relaxed way.
They tend to be in-accurate, but the excitement they display tends to forgive their sins over the short time.
The 215 are reasonably accurate, so don't suffer from the same fatigue, they can be taken very seriously as a transducer of the highest quality.
But, like all full range drivers, they're not really full range and have roll-off at bass and treble extremes.
Eminence make a 15" bass driver designed for open baffle. They cant do deep sub-woofer bass on an open baffle, but these days we have some great tools to coax reasonably flat bass response from these drivers.
However, there's a real problem integrating other drivers into use with full range drivers.
The beauty of full range drivers is that they dont use crossovers, they are used "full-range" and this lack of crossovers preserves the phase response of the driver.
Crossovers ALWAYS do some damage to phase coherence, which leads to a diminishing of openess, soundstaging and imaging - the big 3 when it comes to realism.
Of course no full range driver can do 20Hz- 20Khz , so if the frequency extremes are required , bass woofers and treble tweeters can be added, although crossovers, whether active or passive , will be required.
What I like about the Supravox is it has a nice roll of at the bass and treble points, quite smooth, and this enables us to blend in bass drivers and treble tweeters with crossovers just on these drivers.
We can get away with no crossover on the 215 at all, and this preserves the phase character of it, the magic remains even with the bass and treble crossovers, as they are not effecting the 215 at all.
I used two Eminence Alpha 15" bass drivers per speaker with a DEQX digital crossover with a steep 24dB crossover at 200-250Hz. I also used the DEQX equaliser function to counteract the open baffle bass roll-off, to a certain degree.
In part 2 I will go further into the implementation, power supply and sound quality of this splendid speaker.
"After four years of building a number of different baffles, trying many drivers and fine-tuning passive crossover points, what conclusions have I arrived at? Only one. Anyone reading this can easily and for little cash build a substantially more open, palpable and real-sounding speaker system than they are likely living with at present regardless of cost."
That's a big claim, but the author seemed a genuine guy with some credibility, and I put it in the back of my mind to investigate further at a later date.
The author was describing an open baffle system, (no box, just a flat panel with drivers mounted on it) with field coil drivers.
Field coil drivers use an electro-magnet instead of a permanent magnet to generate the magnetic force to move the voice coil.
They require an external DC voltage to energise the electro-magnet. It's how the very earliest speakers were utilised, before permanent magnets were viable .
These days they are expensive and exotic, and one of the best designers and manufacturers is the French company Supravox.
Recently one of my preamp owners asked me to build him a power supply for his Supravox field coil drivers.
Its a little out of my field of expertise, but an interesting challenge.
Bob sent me a pair of Supravox 215-EC's to experiment with ( and then gave them to me- thanks Bob!)
The easiest way to get field coils going is with a car battery, the 215 are happy with 12V so a 12V deep cycle battery minimum 25 AH will last through an extended listening session.
After a warm up I was impressed enough to go further with open baffle and field coils.
I should mention that my friend Martin Seddon of Azura Horns has been using field coil drivers for some time now, specifically the Line Magnetic LM555W , which is a clone of the Western Electric 555 compression driver.
The realism of his system is extremely impressive , and initially piqued my interest in field coil drivers, hopefully I could pull the same palpable sound from the Supravox.
As you know, i'm a big fan of active speaker/amplification, ie using a seperate amplifier for each driver with either passive or active crossovers.
The Supravox is essentially full range , in the same vein as the Lowther , Coral, Feastrex full range drivers , but the Supravox doesn't have the shouty upper midrange accentuation of these drivers.
However these drivers are known for their dynamics and ease of portrayal of micro-dynamics, they are very revealing, but in an easy, almost relaxed way.
They tend to be in-accurate, but the excitement they display tends to forgive their sins over the short time.
The 215 are reasonably accurate, so don't suffer from the same fatigue, they can be taken very seriously as a transducer of the highest quality.
But, like all full range drivers, they're not really full range and have roll-off at bass and treble extremes.
Eminence make a 15" bass driver designed for open baffle. They cant do deep sub-woofer bass on an open baffle, but these days we have some great tools to coax reasonably flat bass response from these drivers.
However, there's a real problem integrating other drivers into use with full range drivers.
The beauty of full range drivers is that they dont use crossovers, they are used "full-range" and this lack of crossovers preserves the phase response of the driver.
Crossovers ALWAYS do some damage to phase coherence, which leads to a diminishing of openess, soundstaging and imaging - the big 3 when it comes to realism.
Of course no full range driver can do 20Hz- 20Khz , so if the frequency extremes are required , bass woofers and treble tweeters can be added, although crossovers, whether active or passive , will be required.
What I like about the Supravox is it has a nice roll of at the bass and treble points, quite smooth, and this enables us to blend in bass drivers and treble tweeters with crossovers just on these drivers.
We can get away with no crossover on the 215 at all, and this preserves the phase character of it, the magic remains even with the bass and treble crossovers, as they are not effecting the 215 at all.
I used two Eminence Alpha 15" bass drivers per speaker with a DEQX digital crossover with a steep 24dB crossover at 200-250Hz. I also used the DEQX equaliser function to counteract the open baffle bass roll-off, to a certain degree.
In part 2 I will go further into the implementation, power supply and sound quality of this splendid speaker.
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