Why Synergy horns?

In another thread I was asked, if I would provide more details about my speakers, so I thought why not?

I have played on active 4 way horn systems since 2016. First iteration was front loaded bass horn, midbass horn, tractrix midrange horn and tractrix tweeter horn. I worked nicely, with all the attributes associated with well implemented horns. Clarity, dynamics, realistic live sound etc.

However some problems will arise, with such horns. First of all, the center to center distance between the different horns is big, compared to the crossover frequencies. We need to be within 1/4 wave in distance at x-over for a seamless transition. For instance if you x-over from the midrange horn to the tweeter horn at 3 KHz the c-to-c distance would have to be 340/3000/4= 2.83 cm (1.11 inch). This is virtually impossible with "normal" horn configurations. This problem rears its ugly head, at every x-over throughout the audio frequency range. As frequency decreases, the wavelengths gets bigger, but so does the horns in the specific bandpass and then c-t-c also increases. It is a linear problem, that can't be solved with the regular approach, aka stacking horns on top of each other. This creates interference problems and lobing in the vertical response curves, that will color the reflection from floor and ceiling. Secondly a large column of vertically stacked horns, will push the sweet spot (SS) further back, for the horns to be perceived as more coherent and integrated, with one another.

But the biggest problem is that almost all horns beam with increasing frequency, it's their way of nature so to speak. What that means, is that the off-axis FR will not be similar to the on-axis FR. This translate into a poor power response, which is not considered a good thing, in terms of best sound quality.

Luckily we can circumvent all these problems with clever engineering and have our cake and eat it too, so to speak. Enter the Synergy horn.

 

This funny hobby is full of old wives' tales and hard enduring myths. In the last couple of days we have learned that AD/DA conversion is degrading the sound. Analog is better than digital, expensive gear is better than cheaper gear and on and on it goes.

To cut a long story short, a lot of what we do in the hi-fi hobby is just expensive ways to adjust eq profiles and adding some sort of distortion.

At the same time, it's all a hobby that can be enjoyed in many different ways. And the goal is perhaps sometimes the way, i.e. that the joy of testing a new amplifier or new damping feet or whatever it might be is perhaps more fun, than getting good sound with something as "boring" as a DSP. And that is totally okay.

 

People wrongly think that DSP=rooom correction and this makes the dicussion about DSP very difficult. DSP is simply digital signal processing, so a DAC is a form of DSP. Trying to correct the room with DSP is very problematic.

Using a DSP in a system actually doesn't need to be anything different than using a passive crossover except from the DA conversion. An DA conversion in the best DSPs today are considered transparent and measures just as well as a dedicated DA. So you basically just use one component for everything. Saying that the converting degrades the sound considerable is simply wrong, but there are of course DSPs that don't measure well enough. Trinnov is actually an example of a an expensive DSP that doesn't measure great and is likely to add some audible distortion. Even a miniDSP Flex measures better than the Trinnov. From what I understand Trinnov is working on an upgrade (may have already reached the market).

And if when are talking about analogue components in a passive crossover, they will generally introduce more distortion. Not to mention the lack of signal alignment between drivers, and which can't be done physically without adding either diffraction issues or pointing the drivers off-axis causing more specular energy.

Using a DSP and time alignment between drivers is really the one route to true high fidelity, but a DSP needs to be of high quality and be used in a correct matter. If we start to correct what's not minimum phase behaviour (like most of the room response) we're introducing artifacts and this can be very detrimental to sound quality. That's why a DSP should be set up manually by a competent person. Automatic correction generally introduces many new problems which sound unatural to people. But we shouldn't blame "DSP" for this, it's rather the misuse of DSP.

 

Granted, the semantics can get a bit messy and confusing, DSP, DAC, DRC, but I think the arguments comes across anyway.

Bjorn, I agree with you on most of your points and by now you should know which ones, we have been over this before, so I won't dive deeper into that and by the same token, save us both some time

 

Bjorn, I'm a bit curious as to what methods you have tried to correct the sound. I think that you have tried some DRC software, but have you tried to make a correction filter with REW and Rephase? What are your experiences, care to elaborate?

 

What you mean by DRC in this setting? DRC is short for dynamic range compression. Using correct terms is very important.

I've have experience with a good number of different DSPs and softwares. DEQX, several miniDSPs, Hypex DSP (two different types), Audiolense, Dirac, Jriver Media center combined with different VST plugins, Behringer, GroundSound, Danville dspMusik, different softwares in AVRs receivers/processors and a few more from the pro arena.

Trinnov and Lyngdorf have I heard a good number of times and been able turn the Trinnov correction on/off on the fly but haven't worked with them myself.

My experience is that the knowledge of the user is by far the most important factor. Considerable more important whether you use IIR or FIR for example. Both the worst and best systems I have heard have been setups with DSPs, which has taught me that DSP is a double edge sword.

 

Thanks Bjorn. DRC would be digital room correction.

So you have been around the block a couple of times, I reckon. Yes, EQ/FIR/DRC are powerful tools, so the result is of course user dependant.

I know GroundSound in 2 friends familiar setups. A small anecdote, I challenged one of them, to fine tune the Groundsound IIR EQ to his best, and then I put a DRC Designer convolution filter on top of the Goundsound settings and the sound improved and not by a small margin.

I have heard Audiolense in two well regarded setups and those were very good. Acourate in another setup, where the acoustic absorption treatment was overdone. Of course Trinnov, Dirac at shows.

Another audio buddy tried DEQX, but was never happy with the outcome, now he has Dirac and is pleased with that. We are going to test it against DRC Designer, which I know very well and then again compare it to IIR EQ with the same target curve. It will all end up in a small seminar, where we invite people to come at listen to the different filters. Should be fun.

 

I could not disagree more.
”Even a miniDSP Flex measures better than the Trinnov. From what I understand Trinnov is working on an upgrade (may have already reached the market” - this is totally false.
What jitter reduction methods does miniDSP use? miniDSP is a great amateur level tool that works well for a cheap speaker to get decent results. Otherwise, it’s doing way more harm than good.

I don’t want to put down your efforts @schlager, as I understand you built the horns for your own use. I initially thought you were selling them. What I don’t understand is why you feel the need to say “DSP is best” - it’s “my way or no way”. You’re clearly advocating that passive crossovers and systems without DSP and other types of digital band-aids, are the wrong approach.
If that’s true, you’d see a lot more high end systems with DSP! And in fact you don’t see any.

The proof is always in the listening, and the YouTube video you posted is all I need to hear as it furthers my point. I think you need DSP to get a decent result given the choices you’ve made with your speaker design, but it‘s not at the level of a world-class system, not even close. I’m saying this because by posting here you’ve essentially asked for the public’s feedback.

 

And if when are talking about analogue components in a passive crossover, they will generally introduce more distortion. Not to mention the lack of signal alignment between drivers, and which can't be done physically without adding either diffraction issues or pointing the drivers off-axis causing more specular energy.

Hello

What distortion do passive components introduce???? I am not talking about issues about the alignment of acoustic centers I mean a resistor as an example.

Rob

 

Zeotrope, it a public forum, so feel free to comment, no problem.

You would probably not be surprised, that I disagree with you. My experiences with non-DSP systems, is that they never seem to sound quite right. To many serious errors, that you can't repair by changing a cable, amp or what not.

I have of course also listened to analog tube amp driven systems, on top on an uneven frequency response, they bring in this sweetness from harmonic distortion, that at first sounds quite pleasant, but on further listening, you realize that this is not how natural sound is like. TT, don't even get me started

Analog is like driving a horse carriage, quite romantic, but a bumpy road, with DSP you are driving a luxurious supercar, giving you a nice smooth ride, with full control. I know what I want.

 

Hello

What distortion do passive components introduce???? I am not talking about issues about the alignment of acoustic centers I mean a resistor as an example.

Rob

Mostly noise and perhaps frequency deviation.

 

Mostly noise and perhaps frequency deviation.

Totally wrong. By that argument a preamp, amp, or anything with a resistor, cap, or inductor would do that.

You know what DOES add a ton of noise? A poorly designed DAC or A to D converter like the miniDSP. It’s low end gear that’s designed for a low price point, and it’s great if you keep that in mind. With a high end system, jitter and noise have a Huge effect on digital sources.

 

Mostly noise and perhaps frequency deviation.

We are talking passive here how are you going go generate noise or frequency deviation through a resistor??? That makes no sense. And as previously stated it would apply in all uses including Pre-amps, amps and DAC's

Rob

 

And if when are talking about analogue components in a passive crossover, they will generally introduce more distortion. Not to mention the lack of signal alignment between drivers, and which can't be done physically without adding either diffraction issues or pointing the drivers off-axis causing more specular e

This. Before those who would go on to criticize a DSP-based setup as a general stance, it seems at least part of the fallacy here is not realizing the flaws passive crossovers themselves introduce, and which also and not least - apart from what's brought up in above quote - includes the negative impact on amp-driver coupling that they're "facilitating." Indeed for some reason passive configuration and analogue are regarded almost as flawless references that do no harm to the signal, but they do not avoid that in not being the best tools in town (by a mile even), while also proving to be severe bottlenecks (as passive XO's) between amps and drivers.

Using a DSP and time alignment between drivers is really the one route to true high fidelity, but a DSP needs to be of high quality and be used in a correct matter. If we start to correct what's not minimum phase behaviour (like most of the room response) we're introducing artifacts and this can be very detrimental to sound quality. That's why a DSP should be set up manually by a competent person. Automatic correction generally introduces many new problems which sound unatural to people. But we shouldn't blame "DSP" for this, it's rather the misuse of DSP.

Well put, and likely why I haven't yet (re-)implemented automatic, digital room correction in my setup. Everything is done manually, with the aid of both measurements and "golden ears." My specific DSP-implementation therefore acts as a digital crossover only.

My experience is that the knowledge of the user is by far the most important factor. Considerable more important whether you use IIR or FIR for example. Both the worst and best systems I have heard have been setups with DSPs, which has taught me that DSP is a double edge sword.

Agreed

What I don’t understand is why you feel the need to say “DSP is best” - it’s “my way or no way”. You’re clearly advocating that passive crossovers and systems without DSP and other types of digital band-aids, are the wrong approach.

Well aren't you, conversely, advocating the absolute prowess of analogue/passive config. as well? From what I've read from you it's even non-debatable which is better, an obvious effort at least to put to rest any discussion on this matter and place yourself on the other (i.e.: right) side of the fence.

If that’s true, you’d see a lot more high end systems with DSP! And in fact you don’t see any.

If only that was indicative of anything, really. Think business, conservativism, dogma even, conjecture (isn't that ALL too obvious), convenience, association, snobbery, stubbornness, etc. - what prevails as the general direction in audiophilia/high-end shouldn't necessarily be used as a yardstick for the absolute in audio reproduction brilliance. The fact is that any merger between Digital Signal Processing and high-end has a tendency to be brought down for the wrong reasons.

 

Thanks Bjorn. DRC would be digital room correction.

I see. Apart from taking down some low frequency peaks, and which is a compromise compared to treating it acoustically, I don't believe in "room correction". You can correct much of the speaker response and also tailor it some to the room. But the room can't really be corrected with EQ.

 

Totally wrong. By that argument a preamp, amp, or anything with a resistor, cap, or inductor would do that.

You know what DOES add a ton of noise? A poorly designed DAC or A to D converter like the miniDSP. It’s low end gear that’s designed for a low price point, and it’s great if you keep that in mind. With a high end system, jitter and noise have a Huge effect on digital sources.

The irony here is that a miniDSP Flex measures better than the Trinnov. You can see the measurements for yourself at ASR. Some former products from miniDSP were mediocre though, and the company doesn't take great care of areas like aesthetics or good cooling of their products.

We shouldn't fall into the trap of thinking price is a always a good clue to what high quality is. It really isn't. There a low cost products that are very well designed and there are many expensive that are not. But you generally don't get a nice looking chassis in the low cost segment and not always products that are built to last, so there of course trade offs.

Our engineer has repaired and measured many expensive products FIY, and has also re-designed several. Some of these are extremely expensive and have a reputation of being of top quality, but we have seen they aren't at all. They have neither measured well, nor have been built well in regards to having a long life span.

 

Hello

What distortion do passive components introduce???? I am not talking about issues about the alignment of acoustic centers I mean a resistor as an example.

Rob

There's a lot to say about this and it's best to give you some links to read. It will also depend on the parts in the passive crossover. Obviously some are of higher quality than others.

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Passive is only chosen because it makes it easier for the end user, and the market hasn't been ready for active. Any qualitfied engineer knows that active is better.

 

Zeotrope, there is very little correlation between price and sound quality in hifi. Transparent audio equipment does not have to be expensive. I would almost argue on the contrary, because customers of expensive equipment expect it to sound a little different from the other and cheaper alternatives, so companies will often "voice" the expensive equipment a bit.

I believe my MiniDSP is quite up to the task. SNR 112 dB, should suffice. A SHARC processor, I'm sure you could run multiple loops through it, without degrading the SQ. Lot's of test have been made, to proof that AD/DA is in practice transparent to the human ear, so no reason to lose any night sleep over that.

Physical laws do not care about price and it does not help to throw money at the problem.

 

Zeotrope, there is very little correlation between price and sound quality in hifi. Transparent audio equipment does not have to be expensive. I would almost argue on the contrary, because customers of expensive equipment expect it to sound a little different from the other and cheaper alternatives, so companies will often "voice" the expensive equipment a bit.

I believe my MiniDSP is quite up to the task. SNR 112 dB, should suffice. A SHARC processor, I'm sure you could run multiple loops through it, without degrading the SQ. Lot's of test have been made, to proof that AD/DA is in practice transparent to the human ear, so no reason to lose any night sleep over that.

Physical laws do not care about price and it does not help to throw money at the problem.

Price is indeed irrelevant. However...

Multiple A/D D/A loops don't really prove anything. What you can't hear on the first pass, you won't hear in the following...

As for measurements, this can be debated as well - the performance of DACs using test signals may not be an indicator of their performance using complex signals (music).

 

If that’s true, you’d see a lot more high end systems with DSP! And in fact you don’t see any.

There are lots of them out there, and very often they are DIY active systems. I would like to change the High End term to High Fidelity. My end goal is to reproduce what is on the record as untainted as possible, while you are perhaps looking to improve what is on the record, based on how you think instruments sound in reality. So we are probably dealing with two different things.

 

What you can't hear on the first pass, you won't hear in the following...

So if you can't hear it on the first pass, then it would be considered transparent, no?