Hey guys,
Thought I’d make a thread for those interested in getting the very best from the SOTA Purifi driver lineup. And for those of us on the cutting edge, we all know that means there’s only 1 way it can be done, fully active and sealed!
I‘ll be posting information on what I have in the works shortly, but in the mean time feel free to chime in with your Purifi based active/sealed builds, or any questions/comments.
Info on the Purifi drivers under transducers here:
Thought I’d make a thread for those interested in getting the very best from the SOTA Purifi driver lineup. And for those of us on the cutting edge, we all know that means there’s only 1 way it can be done, fully active and sealed!
I‘ll be posting information on what I have in the works shortly, but in the mean time feel free to chime in with your Purifi based active/sealed builds, or any questions/comments.
Info on the Purifi drivers under transducers here:
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Great news for the DIY community! MiniDSP has just released their first high performance DSP/DAC/preamp!
Perfect for high quality Purifi based active speakers when used in combination with the Purifi Eval amp kits
And even has optional Dirac room correction. I’ll be testing it shortly, and let you guys know how it sounds and measures. It only has 4 channels, but it can still be used in 3 way fully active systems. I’ll show you how later on.
Perfect for high quality Purifi based active speakers when used in combination with the Purifi Eval amp kits
And even has optional Dirac room correction. I’ll be testing it shortly, and let you guys know how it sounds and measures. It only has 4 channels, but it can still be used in 3 way fully active systems. I’ll show you how later on.
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Yes, please elaborate on the MiniDSP. I've been wanting an upgrade to the 4x10 for years. Ideally I'd like a 4 way version of SHD level performance along with maintaining an analog input for phono.
I've been using a Hypex NC400 paired with an active 3 way. The lower third of the cabinet is a sealed enclosure with 10 inch woofer. The power and control exerted by a high damping factor class D amp and proper Q cabinet is something to behold.
I've considered trying the PuriFi amps on the bass but I don't think there will be an appreciable performance upgrade. If I'm not mistaken the NC400 measures better than the PuriFi. I'm also not keen on having to contend with the variable factor of the quality of input stage used at the PuriFi input.
I've been using a Hypex NC400 paired with an active 3 way. The lower third of the cabinet is a sealed enclosure with 10 inch woofer. The power and control exerted by a high damping factor class D amp and proper Q cabinet is something to behold.
I've considered trying the PuriFi amps on the bass but I don't think there will be an appreciable performance upgrade. If I'm not mistaken the NC400 measures better than the PuriFi. I'm also not keen on having to contend with the variable factor of the quality of input stage used at the PuriFi input.
Looks like it will arrive late January. Ill let you guys know. The SHD appears to use the same DSP/DAC section as this new Flex unit. However it has an integrated streamer board that may be the source of jitter getting into the DAC section. And it has a built in, very noisy 24v power supply. Where the new flex is only the DSP/DAC/Pre, and it has a DC input, so can be fed DC from a very clean external power supply. So for these reasons, and the cost difference, it was my choice.
The Purifi amps sound and measure better than the NC400, however I agree for pure woofer use, the Hypex amps will be good enough.
The best way to go with the Purifi’s is to just use the input boards they make. They’re done right, and have the option to bypass the buffer stage. They come in both stereo and mono versions. And for very sensitive drivers, or tweeters, the buffer can be bypassed to lower the noise even further.
The Purifi amps sound and measure better than the NC400, however I agree for pure woofer use, the Hypex amps will be good enough.
The best way to go with the Purifi’s is to just use the input boards they make. They’re done right, and have the option to bypass the buffer stage. They come in both stereo and mono versions. And for very sensitive drivers, or tweeters, the buffer can be bypassed to lower the noise even further.
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Another thing I’ll show you guys once the Flex unit arrives is the total system performance of the Flex when used in combination with the Purifi amps. I’ll connect the flex up to the Purifi amps, and take measurements from the amp outputs. Because the only performance that matters is the full system performance from the digital storage medium, to the amp binding posts.
I also plan to prove to you guys how much even the finest passive crossover parts degrade the performance of your system. I haven’t seen anyone ever demonstrate this yet. Most speaker builders know that different quality passive crossover parts sound different. But at the same time they think they all measure the same. Well the problem is their method of measuring them. They all measure with a microphone from the drivers. Well that’s not the way to do it. Just like it’s not the way to measure an amplifier.
The way to do it is by connecting a high performance audio analyzer up to the output of the crossover direct. This way we can measure all sorts of things that passive crossover parts do to degrade performance. And prove the cheerleaders for passive crossovers wrong.
The way to do it is by connecting a high performance audio analyzer up to the output of the crossover direct. This way we can measure all sorts of things that passive crossover parts do to degrade performance. And prove the cheerleaders for passive crossovers wrong.
Drivers that will be used for the preliminary prototypes:
Purifi PTT6.5X04-NFA-01 6.5” long throw woofer
https://purifi-audio.com/wp-content...4-NFA-01-aka-PTT6.5W04-01-Data-Sheet-1.11.pdf
Bliesma T25B 25mm Beryllium dome tweeter
https://solen.ca/wp-content/uploads/t25b6-4.pdf
Bliesma T34B 34mm Beryllium dome tweeter
https://solen.ca/wp-content/uploads/t34b4.pdf
Bliesma M74B 3” Beryllium dome midrange
https://solen.ca/wp-content/uploads/M74B6.pdf
Future drivers:
Upcoming 8 and 10” Purifi woofers.
Purifi PTT6.5X04-NFA-01 6.5” long throw woofer
https://purifi-audio.com/wp-content...4-NFA-01-aka-PTT6.5W04-01-Data-Sheet-1.11.pdf
Bliesma T25B 25mm Beryllium dome tweeter
https://solen.ca/wp-content/uploads/t25b6-4.pdf
Bliesma T34B 34mm Beryllium dome tweeter
https://solen.ca/wp-content/uploads/t34b4.pdf
Bliesma M74B 3” Beryllium dome midrange
https://solen.ca/wp-content/uploads/M74B6.pdf
Future drivers:
Upcoming 8 and 10” Purifi woofers.
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Will the speaker driver be the load because the crossover was designed to be used with the speaker driver. In this case, the PTT6.5.
The measurements you take after the crossover are inter related with the response of the speaker driver. You can’t separate the two as they were designed as a system. I am not sure what you are trying to show by measuring distortion of the electrical signal between the XO and the speaker voice coil.
You speak of system performance and in this case, the system includes the transducer and the final output is the sound wave as measured by a mic. Not the signal after the passive XO connected to the driver voice coil.
It’s fine to to measure amps into a resistor dummy load. No one measures the amp performance into inductive speaker load. For the same reason I am not sure why one would measure the amp distortion after the crossover/speaker load. I am in agreement that wirewound resistors and iron core inductors can add distortion. But so does the “wire wound” voicecoil of a speaker driver. It’s a highly non linear complex system as shown by the equivalent circuit as described by Thiele and Small. This is why we have T/S parameters. In Akabak, or Spice one can easily simulate the effect of the T/S equivalent circuit if good models of the component hysteresis are available. It’s much easier to measure the acoustically produced distortion as that is the final product. Not the intermediate signal between the XO and driver voice coil.
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Do you measure an amplifier with a microphone from the speaker drivers? No, you use an audio analyzer. Just like you don’t measure a DAC from the output of an amplifier, if you only want to know the DAC specs.
I’ll be measuring the undesirable effects such as distortion, noise, impulse response lag etc that a passive crossover imposes on the signal before the drivers. And then I’ll tune the same slopes into the DSP and compare the end results between the 2. It will be an apples to apples comparison between the 2.
And the theory that speakers drivers add so much distortion that the performance of the gear before them is irrelevant is something I think most audiophiles would disagree with. If all amps sound the same, why do you build so many different amp designs?
I’ll be measuring the undesirable effects such as distortion, noise, impulse response lag etc that a passive crossover imposes on the signal before the drivers. And then I’ll tune the same slopes into the DSP and compare the end results between the 2. It will be an apples to apples comparison between the 2.
And the theory that speakers drivers add so much distortion that the performance of the gear before them is irrelevant is something I think most audiophiles would disagree with. If all amps sound the same, why do you build so many different amp designs?
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It will be apples to apples as in the performance you get from setup A, vs the performance you get from setup B.
This of course is discounting the plethora of other advantages DSP brings to the table. But we’ll get to that later. I’ll start with the basics first.
There will be of course. But there’s a reason that you test audio components like DAC’s, preamps, and amplifiers with an audio analyzer rather than a microphone from a speaker driver. Standard speaker tests are not sensitive enough to pickup the changes in performance of the components used before them. Unless they’re grossly horrific. But human ears can. This is why we can hear differences between amps, preamps and dacs when played back though speakers. Even if the results of standard speaker tests may look the same on paper with different amps, preamps, and dacs in the chain.
Yes, apples and oranges because the XO and the speaker drivers were designed as a tuned system. This is fundamental concept of the passive speaker. You can’t take one XO from one speaker and stick it on another set of drivers and baffle, can you? You can, however, take an amp and stick it on any other passive crossover and driver system designed for said amp if impedance and power ratings are within spec.
It would be like measuring the distortion of a Class D amp without the output inductor or capacitor that is part of the LC filter. They are part of the tuned system.
As Danny_66 said, if you want to look at the effect of the XO, the speaker needs to be included. The final output of a speaker XO that is important is the sound wave produced. That’s the output of a speaker. Not the voltage between the XO and the driver. It’s obviously going to be non linear as it is acting on a non linear motor and suspension of a speaker.
It would be like measuring the distortion of a Class D amp without the output inductor or capacitor that is part of the LC filter. They are part of the tuned system.
As Danny_66 said, if you want to look at the effect of the XO, the speaker needs to be included. The final output of a speaker XO that is important is the sound wave produced. That’s the output of a speaker. Not the voltage between the XO and the driver. It’s obviously going to be non linear as it is acting on a non linear motor and suspension of a speaker.
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The DSP will be setup as a tuned system as well. I’ll emulate the exact curves that the passive crossover does.
A friend of mine is building a speaker with Purifi 6.5’s along with Bliesma beryllium tweeters as well. And he’s making both a passive version for luddites, and an active version for music lovers. So it will be easy to compare. Of course both versions will optimized the best they can be optimized.
You may also want to note that not all DSP sounds the same. If one can hear the difference of the xover capacitor, he should hear the difference of DSP. MiniDSP does not still offer neither state of art DSP not DAC, and I'm afraid you would conclude A is better than B because of this...
In my experience, Passive and active have different sound signatures, and I don't think we can generalize one is better than the other. I use both.
I agree. Which is why I said that “MiniDSP has released their first high performance DSP/pre/DAC”.
Do I think it’s the worlds best system? No. I developed my own system to fulfil that role. But it is a commercially available system that anyone can buy. And the objective specs are beyond any amplifier on the market. And light years better than their previous offerings. So it’s a great candidate for an example setup.
I‘m getting the balanced version, which is the specs in the middle column.
Do I think it’s the worlds best system? No. I developed my own system to fulfil that role. But it is a commercially available system that anyone can buy. And the objective specs are beyond any amplifier on the market. And light years better than their previous offerings. So it’s a great candidate for an example setup.
I‘m getting the balanced version, which is the specs in the middle column.
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I have Dynaudio X18 here. I have tested this with passive and active crossover matching the frequency response as much as possible. Used Hypex. It was impossible to match the FR perfectly because of the speaker and crossover behavior, I guess. I saw a little different peak and notch here and there.
Anyway, I actually prefer passive with some DSP EQ applied. X18 is not a cheap speaker, but it does not comes with the most exotic crossover.
I believe that may be the case with what you have experience with. The Hypex DSP is mediocre at best. So I‘m not surprised with the results. Great for subs, but that’s all I’d use it for.
Im using the same DAC, and same amps for my testing. So it will be an apples to apples comparison.