GOTO 6-way TimeAligned Horn System

I want to share my project here, because I believe that this experience can be interesting and I hope to have some feedback, comments, ideas and concerns regarding system I'm building and hopefully answers to my questions. I'm new to horns, so I have a lot to learn and all comments and suggestions are highly appreciated. But most importantly, I hope to get new audiophile friends around the international community :) I had already thread at goodsoundclub, but failed to break through arrogance of Romy (we all know Romy :)) It was productive experience anyway...I learned a lot. And as you can see, eventually my system is Macondo-like.
During last 5 years I have thread at SoundEx (Russian audiophile community) and my system is actually a result of our joint work. Someone helped me with modeling, someone with measurements, someone lend me drivers for evaluation. And of course I had a lot of opinions and suggestions what to do next and were to go! So, this is truly our audiophiles community project! My personal role in this project is audio expertise! I'm listening and evaluating is this idea works or we need to search for another.
I have started with my first 3 way horn system around a year ago. It was hand built by one of the very respectable DIYer in Russia. I was impressed with the horn sound and from that moment I'm never returning to conventional speakers. Dynamic of horns is on another level. And I realized that for me this aspect is crucial. And first time in my life I found out that I can change sound for my taste by adjusting crossovers and changing drivers, so I started!
Before, the only option I had, was to buy speakers...what a boring thing...never happy. Now I can't imagine that I'm buying speaker, because for sure I want something to change for my expectation of sound. So, the only option I have from now and forever - do it yourself. That is why I'm here :)

With 5 years extensive experience with the best HighEnd systems and with the fact that I'm listening only classical (mostly piano concertos) and very often visit concert halls, I have very precise vision of what sound I want to get. If someone asks me to evaluate his system, I always ask to put some piano concertos, because otherwise I have no idea how it should sound. And with my first horn system I was quite happy with mid-range, but wanted more extended highs and I found out that there is some gap between MF and HF channel. So my first challenge was to find right HF driver.
Without budget limits I've tried a lot. Look at this picture:
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After all experiments, I realized, that I can't cover HF with this kind of 4-6kHz+ driver. JBL LE85 1" throat in 1000Hz horn was better than any of them and I compared and liked it more than TAD2001, so JBL got my credibility and I've ordered 2 latest JBL's: JBL 2453 and JBL D2430K D2.
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And I fall in love with JBL2453 in 550hz LeCleac'h Azura horn. It works perfectly for me in 1200-14k range.
After HighEnd exhibition in Munich 2015 my best system definitely was VOX Olympian Living Voice. But highest frequencies where better in Siltech room with their small bookshelf speakers with diamond Seas tweeter. So, I've decided that I need non-horn driver on top of my lovely JBL2453. From goodsoundclub I knew about RAAL Lazy Ribbon 9" and actually this is the only driver in the world which can match with horns with sensitivity. 111db! Even this was not enough and RAAL made special version for me with up to 115.5db! I'm waiting for it and now using another amp to match with sensitivity.
So, I've decided for myself, that JBL2453+RAAL is what I want on HF.
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Blue - RAAL without filter
Green - RAAL with 3uf capacitor
Red - JBL2453 with RAAL

Next challenge was bass! Remember, that I was happy with MF, but my MF was 2m long folded horn. During experiments with Dirac (room correction) I realized how important is time-alignment. So, my idea was to unfold MF horn and design complementary 2m long bass horn!
I choose 11" Supravox 285-2000EXC and we created a model of perfect 46Hz horn with flat response from 70hz to 300Hz.
Here it is...big, ah? :)
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Real measurements were also perfect! Exactly as it was modeled in 3D acoustic research modeling software (3dar.ru) developed by my audiophile friend. And sound was very good. So, I was really happy with result.
But next day, by accident, I got two pairs of incredible bass drivers...GOTO SG-146LD!
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This drivers are truly game changers! First time in my life I heard right bass! Right bass is complete absence of bass in typical imagination, but very realistic reproduction of lowest octaves of piano and other instruments. It is pure as highs! No any artificial boom sound. Just pure tone of instruments. This is what I got from GOTO bass drivers in MidBass 46Hz horn. But I heard coloration in upper bass and measurements showed some fault. Look at this:
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Blue - 11" Supravox in 46Hz horn
Green - GOTO 146 in 46Hz horn

Measurement shows that Supravox is preferable, but subjective listening experience gives no chance to Supravox. GOTO is pure and delicate while Supravox is bold and dirty boom like sound in contrast.
So, I've decided to use GOTO in 46Hz mid bass and introduce another channel - upper bass!
Here I must thanks to Romy as he rised concerns about using GOTO for upper bass. Fs of GOTO is very low (27Hz as I remember) and his believe is that Fs must be close to horn frequency. There is a way to tune Fs - changing volume of back chamber. And luckily GOTO has this option! Look at the back of it:
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Here is an open hole in back chamber. I've closed it and got absolutely different response in upper bass horn:
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Red - GOTO in 200Hz LeCleac'h with opened back chamber's hole;
Blue - GOTO with closed back chamber.

So, I got 55-150hz in 46hz mid bass horn with opened back chamber's hole and 150+hz in 200Hz LeCleac'h horn made by Lukasz from Auto-Tech with closed back chamber. Clever, I think :)
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There is also interesting story about choosing upper bass horn to work from 150Hz. I compared 110Hz Tractrix with 200Hz LeCleac'h in HornResp and decided to use 200Hz LeCleac'h and I'm happy with result! LeCleac'h's "curl" extends lows and SPL is more flat! Subjective listening also confirmed that 200Hz LeCleac'h sounds great from 150hz!
Look again at measurements above: 150hz from 200hz LeCleac'h and my first question is: can someone explain this ?
So, at this stage my system is:
RAAL Lazy Ribbon 9" from 14khz
JBL2453 in 550Hz LeCleac'h from 1200hz
GOTO SG-146LD with closed back chamber in 200Hz LeCleac'h from 150Hz
GOTO SG-146LD with opened back chamber's hole in 46Hz horn
As you see from SPL above, GOTO in upperBass horn works well till 1200hz from which I have JBL2453. So, looks like I don't need MF channel. But I heard coloration again. To get comfortable sound I need to reduce the level of upperbass and that means that something wrong with it. So, it was obvious that I need MF channel. And MF channel was also a challenge.
As you remember, I told that I was happy with MF channel I had, but it is because I never heard anything better. It was K-55 replica from AtlasSound in custom 200Hz exponential 2m long folded horn. After discovering LeCleac'h I've decided that it will be LeCleac'h and created some vision of my hole system:
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But this was before I got GOTO. So you see 2m bass horn at bottom and 270Hz LeCleac'h on top. The problem with MF was to find driver capable to work effectively in 270Hz horn from 350Hz because my 2m long 46hz works till 300Hz only. So, I got:
JBL 2490
JBL CMCD
JBL 2450
Vitavox S2
Supravox 8" 215-2000EXC
LM WE555
GOTO SG-555
With all this choice I was never happy with MF before I got SG-555. With SG-555 I got very pure tone and cut upperBass horn earlier. I'm still going to experiment with crossover and I'm still waiting for my 270Hz LeCleac'h horn. Now I'm using 350Hz spherical horn from Germany.
So, I got 5 ways and with ULF (lower than 55Hz) - 6 ways. And you see, that there is no other choice! Only 6-ways! I've explained in details why I have 6 ways. If you want to get pure open sound from horns without any coloration, than it is 6 ways!
The problem I have now is how to put all this 5 channels together (ULF is separate - is ok, I believe). Here are some renders of some ideas:
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Not very elegant...so, for now, I think to separate mid-bass horn and put it at the back of listening sofa. In this case it will be time-aligned and I can keep 4 channels in front quite elegant.
At the end, I want to post some videos.
http://youtu.be/yd-Ra5qTVkE
http://youtu.be/aX3Nh0Z8Ucw
http://youtu.be/1hNo6Vz7zYc
http://youtu.be/7ougp0NaU7w
If someone has experience in evaluation of system sound through YouTube, than you can post your opinions, if not, than you can get some visual impression of what is going on. MF is still on the floor as frame is not ready. But very soon, I'll combine all together.
Again, I'll be very happy for any comments. I hope that my project is interesting for diyaudio community.
Murat.
 
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Very nice, thanks for sharing your journey. Don't see GOTO bass compression drivers everyday :D If you don't mind me asking these are something like $35k each now?

"The problem with MF was to find driver capable to work effectively in 270Hz horn from 350Hz because my 2m long 46hz works till 300Hz only. So, I got:"

I think that will be a tough area to be covered by many compression drivers and I'm not surprised the ones in your list did not sound good.

Isn't GOTO's own recommendation to use 2 of their lower midrange compression drivers per channel? I think I had read on Romy's site that people were hearing thinness with S150 horn and single lower midrange compression driver (sorry I can not recall model name) when going below 400 hz.
 
Very nice, thanks for sharing your journey. Don't see GOTO bass compression drivers everyday :D If you don't mind me asking these are something like $35k each now?
Accoirding price list available by Google search, yes. But first owner got them 7 years ago for 10k each and sold to me with great discount from that price.
So, it was really great luck to get them.
I was never looking to GOTO side because prices are crazy and how they good I never knew. Now my opinion: if any chance to afford them - new or used - they worth it.

"The problem with MF was to find driver capable to work effectively in 270Hz horn from 350Hz because my 2m long 46hz works till 300Hz only. So, I got:"

I think that will be a tough area to be covered by many compression drivers and I'm not surprised the ones in your list did not sound good.
This range is really interesting. Without it or with much lower level of this range sound is usually even better - more transparent, light and brilliant, but, of course, huge lack of weight and body.
Adding wait and body makes the sound dull with any of the drivers in list except 555.

Isn't GOTO's own recommendation to use 2 of their lower midrange compression drivers per channel? I think I had read on Romy's site that people were hearing thinness with S150 horn and single lower midrange compression driver (sorry I can not recall model name) when going below 400 hz.
I've just got another pair of GOTO SG-555 and my 270Hz horn has 4" throat, so I can make adapter to try a pair for each channel.
 
How did your tweeter tests compare to each other? I never seen a Fostex, JBL, Beyma, etc all in one place to compare. Also, I'm surprised the result was ribbon. I've tried 3 ribbons in my horn system, and they all did not intgrate well with the horn sound (sounded different in coloration.)

Not correct to say that result was ribbon. Result was: JBL 2453 with ribbon on top.
JBL 2453 plays till 14khz and ribbon supports higher that 14khz with significant contribution to 10-14k range, because I use 1st order highpass crossover for RAAL.
Ribbon has not enough weight for HF lower than 10khz while horn tweeters produce something sharp and hard upper than 10khz for my taste in compare with ribbon. When I'm increasing volume of HF with horn tweeters, I feel like they drill my brain. But with RAAL I don't feel anything like this. With too loud RAAL sound picture become too bright with exaggerated details and that's all. BTW, this is very important role of RAAL - to highlight details of sound. I never feel that with horn tweeters.
It is important to say, that RAAL is the only tweeter from my list which is capable to approach sensitivity of JBL 2453 in 550Hz LeCleach. For any other horn tweeter to get 14+KHz, I need to use 3-4 order highpass crossover and than to match sensitivity I need to attenuate JBL2453 and this makes sound poor. So, the only way for me is JBL2453 with RAAL to cover HF range.
What I still want to do, is to try to use 3-4order LowPass for JBL2453 not to allow it to play higher that 10khz.
Another option is to try GOTO-37/370 on place of JBL2453, because I'm sure that GOTO will not go higher than 10khz.
I've already ordered GOTO-37, so very soon I'm going to finally decide about HF configuration.
But for now, JBL2453 is best I ever heard...with RAAL on top :)
 
Ah! I see. I have low pass roll off on my Altec 288 at around 8k. Supposed to get Beyma cp-21 alnico in the mail tomorrow. How did your cp-21 compare? (Yours in newer version) hopefully good. I only paid 1/4 what a JBL 2405 costs used.

I also have Altec 288 (forgot to include with others on picture :) ) and like the tone very much! Very clear and brilliant. But 8k is not enough to match with RAAL in my case, but in your case cp-21 will work well, I believe. JBL 077 is more costly and also falls quite rapidly after 10kHz, while Beyma was ok as I remember. So, I think it is a good match! :)
 
There is more to time alignment than physically aligning the diaphragms of the drivers in the system...

The inherent response (frequency, phase) of the driver AND the response of the crossover filters ALL introduce frequency dependent phase response. Unless you carefully take that into account, your system will not be time aligned. In fact, a system with non-aligned drivers might turn out to be more time aligned (in general terms) when combined with the crossover than one that is physically aligned but the crossover network not optimized for phase/time "alignment".

I have not seen you mention anything about the crossover. Have you given any thought to that?
 
There is more to time alignment than physically aligning the diaphragms of the drivers in the system...

The inherent response (frequency, phase) of the driver AND the response of the crossover filters ALL introduce frequency dependent phase response. Unless you carefully take that into account, your system will not be time aligned. In fact, a system with non-aligned drivers might turn out to be more time aligned (in general terms) when combined with the crossover than one that is physically aligned but the crossover network not optimized for phase/time "alignment".

I have not seen you mention anything about the crossover. Have you given any thought to that?

Yes, I agree completely. At this stage I'm only choosing drivers for my taste and looks like I've finally just settled. I still want to try 505 and 570 on place of 555 and 370 on place of JBL2453, but I like what I got now and ready to move to the next stage - crossovering.
Currently I'm using 4th order lowpass at 50Hz for Tapped Horns, 2nd order lowpass for midbass and upperbass big GOTOs and 1st order highpass for them and 1st order for the rest of channels.
I got very good frequency respones, I'm very happy with tonal balance and now I want to measure group delay and check what problems I have.
But I don't know how to solve them. I'm not sure that I can keep celarance of the tone with more complicated crossover. I can't even use attenuator, becase I hear how sound degrades because of it.
What do you suggest to do to carefully time align my system ?