Jeffrey Jackson wrote:

first, basshorns... the basshorns that I posted here some years back are my straight ~50Hz horns (my memory is fading)... they are 8' long... then rear chamber.. mouth ~ 3' x 4'... throat ~8" x 8"... rear chambers of various sizes and some partially filled with blocks of wood as I tuned resonance... so yes, I also have quite a bit of experience with woofers in midbass horns *with compression* and tuning for optimal results.. measured and listening... I feel that you *must* do both... the one thing that I wish I would have tried was a simple phase plug.. that seems to be the thing that "real" compression drivers have that we don't.. it would be easy.. just turn one from wood... suspend with long screws... of course, this needs to be factored into the horn flare... it adds length, but as we discussed, most midbass horns need more length, not less... and then there is the issue of how much compression.. sigh.. so many variables...

This one?   http://www.GoodSoundClub.com/TreeItem.aspx?PostID=1301

Jeffrey Jackson wrote:

one place that my findings were different from yours was in field coil drivers in my midbass horn... I found that in my application (Jensen F12N) a stronger field really helped the sound... more clarity in the upper reaches of the horn... I have rationalized this as the stronger field is driving Qes down....

I do not see where you see difference. I do report that higher flux really helps to many things but in the driver upper range. The higher flux also affected the lower range of the driver negatively (over-damping the cone). Here is the key, the no one understands about the field coil – the process of setting up a right flux density for a given frequency range is much different then with magnets. Perm magnets demonstrate much more tolerance to perfect flux-to-frequency balance but electromagnet are way too sensitive to have literalsy half octave of perfect flux-to-frequency “sweat spot”

Jeffrey Jackson wrote:

oh.. and the double driver being "better" than one... I should really retract that statement…

I know you would.

Jeffrey Jackson wrote:

so.. now to my new quick and dirty Goto setup... as I began above, I am no longer using my pair of straight basshorns.. I will be constructing something new soon... not sure what just yet.. thinking similar to what I had, but more "wife friendly"... I have moved out of my shop and have to be a bit more domesticated.. but that is a small price to pay to have one of my horn systems in the house again.. ahhh.... so here it is... JBL 2405 ~7k up Goto 370 on 600 horn ~1k to 7k Goto 505 on 150 horn ~220 to 1k Sealed box 15 ~220 down (old Pioneer with cast frame, paper cone, and linen surround)

Well, the key in all of this installation would be your decision about the type of bass horns you decided to go for. Most likely, looking at the size of the room and considering that your wife most like will not allow you to convert the windows in mouths of the basshorn you will go for upperbass horn. Still, if it will be 80Hz horn for instances then you might review how you cross your GOTO 505 driver. I can see you going up in all your low knee crossover points. (Unless you use high order slopes that GOTO moronically recommend). BTW, looking at the picture it is a clear self-evident my objections to the negative opening of that French profile – it doe very nice at HF but at the horn that rolls of at 1000Hz the negative opening is just a waste of so valuable vertical space.

Jeffrey Jackson wrote:

at the moment I am biamping with speaker level crossovers.. Eimac 75tl on horns and SE845 on woofers... I have so many "next steps", but likely next will be to line level cross...  I *know* how much better line level crossovers are.. every time they astound me...

This is a complicated subject all together and it’s alone might des own thread. The line level crossovers, although they over unquestionably a lot of multifaceted advantages, might be quite complicated and ambiguous thing to do properly. I spent 2 month with the line level crossover for my 6-chennal Super Milq…

http://www.goodsoundclub.com/GetPost.aspx?PostID=5780

Jeffrey Jackson wrote:

then new horns for Goto drivers..

Romy

I had a SG370 mid apart only yesterday.I should have taken a photograph.I have also seen the inside of the tweeter.They are very similar,so I have no reason to suppose the low mid SG 505 will be much different.

I'll try to explain.I think they are in basic structure close to the WW 555. Taking your default JBL 375 for comparison:

The Gotos are of course "Burpers" as opposed to "Farters" like JBL.i.e they use the front (convex) output of the dome for radiation.They come apart as the magnet on one and the dome + phase plug on the other side .They have a very similar appearance to a standard metal dome tweeter.The phase plug appears to be a simple "bullet".

A few observations.The dome on the mid is about 4cm diameter and very beautifully made.It is obviously very thin and delicate compared to the JBL.It has no metal surround but is bonded to a FEP film that is glued to the flat surface surrounding the phase plug.This film is surprisingly big and really very thin and covers a big area.According to Goto this is one of the secrets as conventional compression drivers resonate in the surround(cf the different resonance patterns -frequency response in the otherwise identical JBL 2440 and 2441).

The rear of the dome sees no damping. The only rear chamber would be the minute area formed between the rear of the dome and the front of the magnet assembly.There seems to be a tiny pin prick hole in the magnet assembly,but I have no idea if that acts as a  kind of vent.-I doubt it.

All in all it appears exceptionally simple ,but exquisitely engineered.I have no idea how that membrane can be accurately glued-certainly not a field job!.There are no guiding pins,but 2 dimples in the front magnet face where the terminal screws go. I suspect that these may act as alignment guides as the front screws are tightened to match up.I opened mine because I thought it was scraping.The scrape seems to have originated from the front screws working slightly loose durng shipping-gentle tigtening immediatel solved this.

I was very disappointed in your tweeter battles that you never tried a Goto tweeter.Like you I really loved the Celestion SL6/600 tweeter's tone,but ultimately found them a bit slow.The Gotos I feel has that tone,but also speed and of course efficiency.All in all I think the best highs for me- I come from a tradition of "British "sound so you may not relate,but I think you will.

Johan Dreyer wrote:

I had a SG370 mid apart only yesterday.I should have taken a photograph. I have also seen the inside of the tweeter. They are very similar, so I have no reason to suppose the low mid SG 505 will be much different. I'll try to explain. I think they are in basic structure close to the WW 555.

Johan Dreyer wrote:

A few observations.The dome on the mid is about 4cm diameter and very beautifully made.It is obviously very thin and delicate compared to the JBL.It has no metal surround but is bonded to a FEP film that is glued to the flat surface surrounding the phase plug.This film is surprisingly big and really very thin and covers a big area. According to Goto this is one of the secrets as conventional compression drivers resonate in the surround (cf the different resonance patterns -frequency response in the otherwise identical JBL 2440 and 2441).

Johan Dreyer wrote:

All in all it appears exceptionally simple ,but exquisitely engineered.I have no idea how that membrane can be accurately glued-certainly not a field job!.There are no guiding pins,but 2 dimples in the front magnet face where the terminal screws go. I suspect that these may act as alignment guides as the front screws are tightened to match up.I opened mine because I thought it was scraping.The scrape seems to have originated from the front screws working slightly loose durng shipping-gentle tigtening immediatel solved this.

You have to be very careful with it. It is remotely possible that the driver has no alignment mechanism and centered by gluing of the VC. This method of diaphragm setting has own plusses and minuses. About your scraping sound – the compression drivers should be cleaned once in a while and they might pick some dirt from air. It is normal.

Johan Dreyer wrote:

I was very disappointed in your tweeter battles that you never tried a Goto tweeter.Like you I really loved the Celestion SL6/600 tweeter's tone,but ultimately found them a bit slow.The Gotos I feel has that tone,but also speed and of course efficiency.All in all I think the best highs for me- I come from a tradition of "British "sound so you may not relate,but I think you will.

I am not disappointed in my tweeter battle. It is a different thread, if you wish I will be happy to explain my view on the subject. I did not tried Goto tweeters though in my system.

Jeffrey Jackson wrote:

so a few things... one, there is a pair of Goto 370 on eBay and pictures of insides... the newer ones are made the same, but it seems that the execution has gotten a better/cleaner compared to these.. my diaphragms look smoother and the glue seems to be neater... I may be able to dig the pictures out of an old email if needed... I lost a lot in a drive crash a few months back... my fault for not regularly backing up...

Yes, thank for point out. The driver looks like OK, though the price is slightly higher than a new pair of Goto 370

http://www.eifl.co.jp/index/goto/goto.htm

If someone would like to give Goto a try then here is an opportunity for you with $3K admission ticket. It I had this option in 2001-2002, when I was going through the drivers, I would most like to try it…

Jeffrey Jackson wrote:

field coils.. well, though I do also hear that you improve some areas and worsen others when varying voltage and therefore Qes, field coils and permanent magnets aren't different with regards to how they react to frequency... you certainly may find a permanent magnet driver that you like across the full band of the horn, but it isn't really due to the permanent magnet... as with all drivers, the magnet is just one of many variables.. I think the horn should be built to compliment the driver, whether field coil or not, just like any driver.. and maybe view the field coil as a bonus that will allow fine tuning once in place.. I do hear some things about field coils that I don't hear in permanent magnets.. but it is hard to say that it is directly due to field coils... I think, in general, they do sound a little smoother.. less grain... but this isn't a proclamation of "field coils are best" because I haven't really found that to always be the case... especially at low frequencies.. too many other things are more important...

I absolutely agree and I was pitching the very same few in all my field coils writings at my site and everywhere else. Unfortunately not one look at the drivers, magnets, horns, loading, utilization as a big unified picture and very few assess the sound of this picture without hysteria, using competence and lucid judgment. Usually people see the field-coils they roll eye and loosing freaking consciousness. I witnessed in a past as some idiots (hi-fi industry professionals) were listening field-coils and went over the exuberant glorification of what they heard, highlighting that it clearly auditable advantages of field-coils. The fan part that they during that listening session head not field-coils but permanent magnet speakers….

Jeffrey Jackson wrote:

so my goto system... well, the basshorns are slowly being built... they won't use goto, though... (at least at first... but I may try an extension and my 505 drivers).. straight six foot 60 Hz horns... mouth about fourteen square feet... I am stil planning for physical time alignment to try to avoid digitizing my analog at this time.. I may change back at a later date... but you misread my wife... she doesn't mind large, just doesn't like unfinished R&D style horns... so I have to actually finish them, something I normally would only do for customers...

I was asking about Ming’s frustration with his big horns, I did not know what you were doing. So, it will be straight six foot 60Hz. Very cool. It is what I would do it I have a room and an abuseable person why would do it. I long time ago prepared the drivers for the projects and it is just wait for a right time.  I did not know that you do it as “job for customers”. Would you care to do some pictures? Also, how expensive that project in nowadays prices? I am not asking because I would like to move now into it myself now but others should know that there is an opportunity to do it.

Jeffrey Jackson wrote:

and why did I choose goto you asked? ….seemed to fight off congestion at high volumes on complex music better than any I had heard....

Those few time what I head GOTO I did notice the same. They did look like have very nice ability to sound under stress… I have a big theory about it and I feel that the less power handling of a driver the better it sounds under stress.

Jeffrey Jackson wrote:

….another big selling point to me was the 505 being a low resonance compression driver.. there just aren't many drivers with a resonance in the 80 to 100 Hz range like this driver... I have just begun my playing, but am already quite taken by it... this driver and its 48", 150 Hz horn will likely be the last thing I change.. it sounds very good...

As I understand you are planning to use the 505 with 150Hz and below will be the 60Hz horn. Might ask you how you are planning to stop the response from lower horn – with a sharp filter? That is one of the bottleneck that I have no solution and I do not what to go there with 3-4 order.

Jeffrey Jackson wrote:

I am beginning to get slightly dissatisfied with the 370 on the 600 horn.. and I think it is the horn.. I think I must be spoiled by the leCleac'h and conical flare horns and their ability to radiate a more even power response into the room.. the result, to my ears, is a more natural and "open" sound.. maybe less focus, but it is hard to say for certain... luckily, I can easily turn horns of this frequency on my lathe..

be wrote:

"another big selling point to me was the 505 being a low resonance compression driver.. there just aren't many drivers with a resonance in the 80 to 100 Hz range like this driver... I have just begun my playing, but am already quite taken by it... this driver and its 48", 150 Hz horn will likely be the last thing I change.. it sounds very good..." Hm, I dont really know about this, I heard a GOTO system with the GOTO 505 in the GOTO 150 Hz horn and I found it to go anemic in the lower range, I think a FANE M8, that I heard briefly during some experiments, would do better in this range with a similar horn. I dont think it is a coincidence that GOTO systems sometimes have two parallel drivers on the lower midrange horns.

Be,

Do you think that that based upon your experience with GOTO and FANE it might be possible to generalize “what is better”.  It is upper bass and it is upon many valuables: Imbedded Macro-Positioning, appropriateness of a given horn to the given driver, specifics of the given implementation of driver loading, specifics of the driver electrical damping by amps, a listening ignorance of a person who implemented a given solution… and many other factors. So, the specific positive or negative results (or a result as in your case) are not indicative to illustrate of “what is better”. I am not willing to pretend that I know an answer to the question “what type of driver is better for upperbass”. Let us to think at the subject together from slightly more divert perspectives.

The debate as I understand is about: to use a compression driver or do not use compression driver for upperbass. The people around Steve Schell circle love to drop tears that “there is nothing like bass from a compression driver” (link). I usually laugh when I hear that pontification. I also whenever I hear upperbass from compression drivers never found it even worth criticism – it was just very bad, including what I heard from Steve Schell demonstration. Still, I would not accept is as defeat of the compression driver for bass notion. Let look what we are actually debating.

The people who uselessly use compression drivers for upperbass practically never use the compression drivers properly. The bass-able compression drivers with low Fs are rare. People have the only one type of the horn that the can afford space-wise for upper bass and they got those rare and expensive compression drivers. However, there a compression driver has ONLY ONE already SET resonance frequency and it have the only one optimum horn for that frequency. No one I know consider it and peoples juts plug the compression driver “as is” into the horn that they have. No one will pay $$$ for GOTO drivers, build horn and… then take a blowtorch and blow away the GOTO’s back chamber, biding own back chamber with the Fs characteristics that would be necessary for a given horn. Be advised that with new acquired Fs characteristics the GOTO (for instance) diaphragm type and suspension might be not winning anymore and we are talking about the new completely open Pandora box for multitude of dilemmas.  There is also a diminishing return with compression driver bass. We have 3”-6” diaphragm the need to push 300Hz. It does it and we call it OK. Then we need the same 3”-6” diaphragm to push 80Hz. The dimension of the diaphragm in compression driver does not wary a lot and in order the 3”-6” diaphragm to push more bass the suspension should be softer and the cone’s excursion should be longer. So, we produce more bass by let the diaphragm to run furthermore but it has a LOT of potentially bad results. The longer excursion means the gap should be with less tolerance with more flux wasted.  The longer excursion means more mechanical contribution from the cone and it’s suspension to the drivers. The longer excursion means the compression of the front chamber impact the cone more different at the beginning and in the end of the excursion. I mean the low excursion is one of the main advantages of any compression driver – we do diminish this advantage what we go in bass region.  Also, we do not know how the given driver’s cone will break-up when it is dumped for a given horn. I do not support the bogus believe about the piston motion of diaphragm – the REAL sound is create inside the diaphragm break-up…

Ok, on the other side we have my Fane-type of application for upper bass. The application is call to found as proper cone driver with necessary characteristics and to use is as a compression driver. Pay attention: it is not a cone driver loaded into a horn, it is according to all definitions’ is a compression driver application. What is the difference with the GOTO approach? The difference is that by selecting of the driver, type of the cone, type of the suspension, the driver performance at the given cruise dumping, size of the driver,  mass of the cone, way to damp the driver and many other characteristics we virtually reconstruct the compression driver, only we do it with respect to our given horn.  It is important to note that in both cases we are screwed: in GOTO-type case we’re screwed with fixed design of a compression driver and in FANE-type case we’re screwed with deficiency of good drivers for our specific application.

The funny part is that I never was exposed to the results where both: the Fane-type and GOTO-type were implemented in horn properly in respect to own topology. I would be no surprised that in the case of proper use the GOTO-type approach and Fane-type approach would perform identically properly. After all, the famous Russian writer Leo Tolstoy once said “All happy families resemble one another, each unhappy family is unhappy in its own way.” Why do you think it should not applicable to the ways to get upperbass from horns?

So, I feel that there is no “better way”.  I am a big fan of compression drivers but I feel that lowering the frequency where compression drivers are used the amount of efforts to get the proper result increase in geometric progression. There are solutions for all problems I have mentioned above but at some point it becomes a pursuit of a concept for the sake of concept. The best way is to have Mr. Goto or somebody similar to built custom drivers to your own specification but I doubt that this task is accomplishable within one life span as it takes years and years to understand Sound and how to create it… unfortunately...

MINGSU wrote:

I finally received the GOTO SG38WNS 15" woofer and GOTO SG188S tweeter this week. My next step is to build a dual driver bass cabinet to cover 70Hz down.

be wrote:

Both the Fane and the Goto where used as compression drivers, so there where no principal differences of use.

Wow, who made such experiment? Bring this person to my forum, it would be interesting to interview him! I still do not know about the “principal differences of use”. If Fane and Goto were loaded in the same horn then how that person equalized the system primary resonance? Then there is another ketch: Goto and Fane cones/suspension are very different and they might (and most certainly will) react differently to proximity to the throat reactance. Go figure if the Goto and Fane were used identically properly in respect to own topology.

Let to be honest, if I had borrowed Goto drivers then I would do the same: juts plug up one, then another and then listened what was better. I would NOT modify or rebuilt a new horn to accommodate it to Goto needs. It is possible that Fane as compression used Fane is better driver for bass, in fact is it what I based upon my theoretical assumptions, some of them listed above. However, I would like do not send a message to others that bass compression drivers is a not perspective direction to go. I think if the bass compression drivers are properly implemented (no one does it) then they might be fine. Still, I personally feel that the threshold of the diminishing return with bass compression driver located somewhere around 150Hz. To go lower with compression driver does not make practical sense.

be wrote:

The sound of the Goto 505 in the lower range was similiar to what you hear from a 8" woofer trying to do what a 15" can in the bass.  Although the sound was clean as free of distortions, it lacked impact and authority.

Well, makes sense of course. Only God knows what the Goto 505 primary resonance is. The company claims the frequency response 100Hz-6KHz (loaded) with no further information about primary resonance. For a manufacture that does ONLY drivers it is very bad do not release more data about their drivers. Here is what Fane has:

http://www.romythecat.com/Site_Images/FaneStudio8M.jpg

be wrote:

Maybe it is not a problem with the Goto driver, but maybe there are limmit to horns ability to transform great ratios of impedance, just as there is with electrical transformers? The air presure at the beginning of the horn in the Goto case will be higher, maybe the non linearity of air starts to be a factor producing compression?

An interesting question. You presume that higher compression has problems to be transfer over the horn. I know very little about it and I generally disregard the theory of pressure conversion in horn as anything that explains Sound in horns. A week ago I have replied in another accidental site to a comment about the horns purpose:

Jdza: The function of a horn is to couple the very high acoustic impedance at the loudspeaker to the very low impedance of the air in the room so a giant transformer with no iron, no wire-just pure clean air.

be wrote:

I shold make it clearer: The Goto was used in a Goto 150Hz horn, crossed at 180Hz. I guess that is a proper implementation for Goto. The Fane was in a 140Hz tractrix horn with a 10cm throat and a not optimised (to large ) back chamber, and no crossover downwards. That is not optimal, but it still sounded better at the lower range.

MINGSU wrote:

SG505TT + S150 horn crossover at 180 Hz is not recommended by GOTO.  The SG505TT driver is not recommended to use with single throat S150 horn.  Double SG505TT driver is recommended to use with single throat S150 horn.  To use single throat S150 horn, GOTO recommend to use the SG570 driver.  The crossover point for S150 horn should be 200Hz and up to 1kHz only with 1st order/6dB active filter.  For passive filter, 2nd order /12dB filter is recommeded.  Hope this help.

MINGSU wrote:

Hi All, This is Ming Su and I am the US distributor for GOTO and J.C. Verdier.