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Topic: Its even possible to make my midbass...

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Posted by Romy the Cat on 05-06-2007
I had quite a number emails from different people who picked 515G or AK15X drivers and would like to build a midbass horn from 60-80Hz to ~500Hz. I played a lot with different 515 (B, E, D, A) and with different AK15X but I never went for the right horn myself and therefore I can judge only conceptually and upon the numerous applications of 15-inchers by others. This does not make me really qualified on the subject as I never was pleased with the result that others got.

So, this is your thread the Altec 515G users. If you have a motivating experience how to get interesting Sound from this driver (perhaps not only in horn application) then feel free to share…

The Cat

Posted by Romy the Cat on 05-11-2007
What surprises me that no one express interest to the idea of making a bass horn with a fifteen incher. Many people did it, many peoples what to do it and most of their efforts were not successful sonically. The really is that to make a good sounding horn around 15” driver is VERY DIFFICULT and therefore I thought that people would comment about the success and perhaps failures. What I get time I will post some of my observations about the subject. Be advised that I DO NOT KNOW how to make it properly but I did experienced many wrong sounding horns driven by 15 inchers…

Posted by RonyWeissman on 02-08-2008
Can I have some opinions on a potential mid-bass driver for my Altec 515s, as pictured in the attachement?  What are the obvious or potential problems I should address?

see attached photo: 120 Hz - @800 Hz.

For the Altec 515 such a horn should be about 95 cm high (from upper to lower lip), 90 cm wide and 60 cm deep over all.

This horn ends with a flange, which can be made costumized. The flange should be attached to a cabinet for the ALTEC 515. The cabinet should have about 100 litres und optionally be tuned to the resonance frequency of the system.


I hope you can open the picture, I was unable to use the image gallery to upload the file.

Thanks

Posted by Romy the Cat on 02-09-2008

Rony,

I am not exactly understand what you are trying to do and what kind of cabinet are you trying to attach in the back of that horn. Perhaps I misread you. There are two types of Altecs 515: the G-like and B-like – they are very different type of drivers. There are other letter, A, C, E but they all still comply with the two types above, whish one you use? Generally pushing the Altecs 515 all the way up 800Hz is too ambitions, I feel they begin loosing at much lower frequency, but it would be all depends what is your next channel and what it will be able to do at the bottom…

One thing I would like to note. I do not think that it make send to ask about obvious or potential problems in your situation. I know a lot about upperbass sound and particularly horns and juts because I do know a lot I assures you that a sensible specific implementation at a give location might override the design problems and shortcomings – come it is almost bass! So, the most accurate question would be not what is wrong with your horn and what you feel is wrong with the sound is produces. Perhaps from there it would be more reasonable to recognize where you stay your expectation in upperbass and how the given implementation might or might not serve you.

Rgs, Romy the Cat

Posted by RonyWeissman on 02-18-2008
Hi romy,  mine are the 515-G drivers.  I will be x-ing over at 600hz to Vitavox S2's (2nd order, yipes!).  The S2s are in 320hz LeCleach horns. 

I was kind of hoping for just a general reply like when you guys look at a picture of a horn set-up that instantly strikes you as moronic...(picture posted above of midbass horn). 

For example, is the shape of the horn something that strikes you as silly, the throat size relative to the horn, is it reasonable. The rectangular shape of the throat opening, is it a mistake, etc?

Someone is willing to build it for me, but I will have to finish the wood.  If I remember there is a lot of info on this site about the proper finishing of horns, so I will look there for that.

If it's really to general a post just ignore me and I will post again after finally installing.

Thanks,
R Weissman

Posted by RonyWeissman on 04-04-2010
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Hi Romy,If you have a moment between setting up your gear in new room, can you point me to the thread where you discuss suggested wood horn finishing techniques? I can't find it.I am hopefully on verge of placing order for my first mid-bass horn for the altec 515-8G, and the standard finish is clear lacquer on either red oak or cherry wood.  I could ask the guy to leave them rough though and i'll finish them myself?Thanks,R Weissman

Posted by Romy the Cat on 04-05-2010
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Ronny,

You can look among those two threads.

http://www.romythecat.com/Forums/ShowPost.aspx?postID=6436

http://www.romythecat.com/Forums/ShowPost.aspx?postID=3710

I do not feel that for midbass horn a surface makes any difference at all. It rather the surface hardness instead of the surface finished smoothness. I would personally like the textured finish – better sound at HF, better match across all channels and very easy to retouch it if damaged.

I do not know who your horn makers but from what you say I do not like them. The people who propose clear lacquer finish do not charge for form but for the finishing job on the horn. Also, to make horns from either red oak or cherry wood I am sure will look sexy, particularly stained and lacquer but it is about look not about the purpose.  The look might be an important thing but we do not need to discuss the look - everyone desire for themselves. I just would love to know that your horn maker spend as much efforts assuring the your horn to sound better as much as he intend to spend on it’s appearance.

BTW, if you intend to leave them rough though and finish them yourself then be advised that it is not so simple and it does require some techniques, infrastructure and tools…

The caT

Posted by Macman on 11-02-2011
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New to the forum...

I know this is an old thread but Im posting my question here anyway.

I express interest in the idea of making a basshorn with a fifteen incher. Im in the middle of making a 4 way hornsystem involving a hornloaded 416-8A driver working in the range of ~100Hz to ~500Hz. I admit I have not been able to read the entire forum, but if you know, which undoubtedly you do, about threads that regards more or less successful midbass horns with fifteen inchers i would be greatful if you could point me too them.

Regards,

Macman

Posted by Romy the Cat on 11-02-2011
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Macman, it is too broad question to be answered. If you need any usable specific then you need to do your own homework and defend exactly what you want and how you want. BTW, then you would not need neither me nor anybody else.

Posted by Macman on 04-09-2012
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Romy,

I did my homework...

IMG_0455.JPG

midbasshorn for a 15 incher, + a little extra

Regards
Marcus

Posted by Romy the Cat on 04-09-2012
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Hi, Marcus

As I understand it is 15” loaded into 110-150Hz horn, MF compression driver in 350-400Hz horn, Ribbon tweeter and a pair of tapped horns? Looks good.

If it were up to me than I would paint the entire baffle with tweeter and MF in black– in my view it would make the whole speaker more organic. This is however just visual part. There is some functional, more important part.

The tweeters are mounted flat at the baffle and it is not very good. Do you do not want to have any flat surface around tweeter as it give some HF reflection fog. I am sure that the tweeters are time-aligned, so you can’t move them. You however might cover the front of baffle around tweeter with some think soft material to minimize the reflections. The throat for your upperbass horn looks a bit too large but it is what it is. The tapped horns look very nice but they must be outside the upperbass not inside. Moving then out you will gain a LOT of imaging.  You also, if you crossover point on tweeter not too low, might want to exchange the position of MF and HF channels. Ribbon tweet are hobble MF drivers, do not believe the people who say contrary. The only reason I see for you to put the tweeter in such a prominent position is because you drive it too hard and it crossed too low. With 400Hs horn that you use you might get good 10K out of your MF and if so then I do not think that your tweeter needs to be in your ears level anymore.

Anyhow, good work, keep the speakers further from the back wall and play with toeing-in and out.

The Cat

Posted by Macman on 04-10-2012
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Hi Romy,

Its an Altec 416-8A driver in a ~100 Hz exponential horn, Jbl 2441 in 350Hz tractix, Aurum Cantus G1 tweeter and Eminence Definimax 4012 HO in ~30Hz Tapped horn.

I just hooked it up and the highs are promising but I thought the lower end (200 hz and below) would be this setups stongest register but that has yet to show itself. Hopefully this will be something that is modifiable. I still dont have a good set of electronics but I think you would be able to hear the potential even so.

The altec driver when I got it, was used in an altec valencia. I had some time to listen to it during the building process and the bass that it was able to deliver was astounding. Really tight and fast. I thought that it would exell in the midbass horn but the "kick" just isnt there. The throat is 8" in diameter which I belived would work efficiently. I will catch you up on the "padding" around the tweeter, I just couldn´t come up with another solution for the tweeter placement. The tweeter and the 2441 is currently crossed over at 7kHz and I think it works out pretty good. The 2441 doesn´t appear to do a very good job at the higher Frequencies.

As It seems now the biggest letdown is the TH. The transient response is nowere to be seen and the sound is just loud and muffled. The dynamics is awful and the fast bass that I was looking for isnt there. I don´t know if I made some mistakes when I made it. I used a 12" because I wanted to have a driver that moved a lot of air so I could feel the bass as well as hear it. I know John knows THs well, maybe he have some thoughts. (the possition of the THs inside the other drivers is just temporary).

Regards
Marcus

Posted by Romy the Cat on 04-10-2012
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Marcus,

here is absolutely nothing wrong in what you describe. I absolutely assure you that any single person initially end up with the results similar to what you describe. Most of them stop there and do not understand that they got very bad results and I very much assure you that dominating majoring of the shiny DIY playback that depicted within Web do sound very similar to the result you got.

Anyhow, now as you built the bone of your acoustic system it is the time to make it to sound appropriately. It might take for a while as you will not be dealing only with sound of playback but rather with self-education and moderation of own expectations. His is normal.

I know about the subject too much in order to advise you anything specific. Get phase tester, get RTA, get recordings that feel comfortable and start to experiment. As the speaker bone built to make the speaker to sound well is truly fun – it is like riding a wild horse… Have fun and keep the eyes on the ball…

The Cat

Posted by Macman on 04-10-2012
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Romy,

Just realised that I had dual highpass filters on the TH, which more or less cut off frequencies below 50Hz entirely. A lot better now, still much to be made of course.

/Marcus

Posted by noviygera on 04-11-2012
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 Macman wrote:
Hi Romy,

Its an Altec 416-8A driver in a ~100 Hz exponential horn, Jbl 2441 in 350Hz tractix, Aurum Cantus G1 tweeter and Eminence Definimax 4012 HO in ~30Hz Tapped horn.

I just hooked it up and the highs are promising but I thought the lower end (200 hz and below) would be this setups stongest register but that has yet to show itself. Hopefully this will be something that is modifiable. I still dont have a good set of electronics but I think you would be able to hear the potential even so.

The altec driver when I got it, was used in an altec valencia. I had some time to listen to it during the building process and the bass that it was able to deliver was astounding. Really tight and fast. I thought that it would exell in the midbass horn but the "kick" just isnt there. The throat is 8" in diameter which I belived would work efficiently. I will catch you up on the "padding" around the tweeter, I just couldn´t come up with another solution for the tweeter placement. The tweeter and the 2441 is currently crossed over at 7kHz and I think it works out pretty good. The 2441 doesn´t appear to do a very good job at the higher Frequencies.

As It seems now the biggest letdown is the TH. The transient response is nowere to be seen and the sound is just loud and muffled. The dynamics is awful and the fast bass that I was looking for isnt there. I don´t know if I made some mistakes when I made it. I used a 12" because I wanted to have a driver that moved a lot of air so I could feel the bass as well as hear it. I know John knows THs well, maybe he have some thoughts. (the possition of the THs inside the other drivers is just temporary).

Regards
Marcus

Marcus,
I have an Edgar 80hz midbass with a 15" EV driver. I am not happy with the sound I am getting, as well, and I believe it is in part due to the 15", as well as a not proper horn enclosure. But somehow I am sure that for the 100-500hz range a smaller size driver will be more appropriate to integrate with a midrange section, especially if you are using a good compression driver.
After testing numerous 8", 10", 12", 15" (paper cone) drivers in the 100-500Hz range I came to the conclusion that to have good resolution and detail you must have at most, a good 10" or smaller.  Use multiple 10" or 8" in your existing horn maybe. I believe messing around with any 15" for 100-500hz is a waste of time. How can a 15" properly transition sound to a compression driver -- I don't believe this, from my experience. It will be too slow and rough.
Herman


Posted by Macman on 04-11-2012
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Herman,

Im sure you are right about what you are saying and it makes perfect sense. In the Valencia though, the 416 was crossed over at 800Hz to an even smaller(1") compression driver and to me it sounded really good. The reason I chose a 15" in the first place is the same reason I chose a 12" for the TH. It moves a lot more air than a smaller driver, which in my world would make one "feel" the sound better. Maybe Im wrong about this but for me it makes sense.

As it seems the system is pretty tedious to listen to for longer periods. When only listening to the midbass horn I get kind of "ringing" in my ears which I think might be the reason for this. I think that might be because the entire horn is vibriting. When you think about it the horn kind of looks lika a bell of some sort. Someone might know of a way to ease the vibrating? Alternate mounting technique of the driver perhaps, or some kind of "grouding" or coating?

/Marcus

Posted by Romy the Cat on 04-11-2012
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 Macman wrote:
Just realised that I had dual highpass filters on the TH, which more or less cut off frequencies below 50Hz entirely. A lot better now, still much to be made of course.

This is very normal. People get the “building plans”, render it in wood and presume that it has to be assurance of some kind of “good sound”. There is nothing further from truth. As the bone of the speaker structure is built you just start to make your speaker. If you are sensitive to what you do then you will go over many events, from very useful self-realizations to openly stupid actions – that all normal and it comes with the game. You need to find a way to properly load and cross your 416 driver.  I am sure your 2441 driver is a piece of crap. All vintage drivers are crap- and they need to be serviced, cleaned, aligned and calibrated to perform properly. Do not be in harry to make any concussions unit you make each channel to operate at its best and make the whole system to sound in uncompromised way. It will take some time and some efforts but that is OK.

 noviygera wrote:
I have an Edgar 80hz midbass with a 15" EV driver. I am not happy with the sound I am getting, as well, and I believe it is in part due to the 15", as well as a not proper horn enclosure. But somehow I am sure that for the 100-500hz range a smaller size driver will be more appropriate to integrate with a midrange section, especially if you are using a good compression driver.

I think a conversation about size of the driver has very little relevance. A common colloquialism says: it is not about size but how it is being used. In horns the colloquialism works perfectly fine: it is not about size of driver but the size of the throat it loaded into. The problem with Edgar-like 80hz midbass and the Macman’s 100Hz horn is not the large driver but large throat that has low mouth to  throat ration and do not provide sufficient horn equalization. It still might be made to work very well but it still will have some fundamental restraints.

The Cat

Posted by Jorge on 04-11-2012
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Hello Macman,

Nice horns, I like that you finished everything properly!  I am getting tired of seeing piles of horns.

I think the ringing you are getting from your midbass horn is that the throat reactance is not balanced.  How did you calculate the back chamber of the Altec woofer?  Can you make some adjustments?  Usually the "ringing" can vary in freq. depending on the size of the back chamber.  Make it smaller or bigger and check how the ringing goes,  get used to the ringing and learn to identify it, you will need to find it to get rid of it!  If you think a 120 hz horn ringing is a problem, wait untill you try a 140 or 180 hz horn!!!  Now that is a mess at very listenable frequencies! 
When Romy said: live with your midbass (upperbass) horn for a while, I guess this is what he meant.


"to me it sounded really good"   Then why in hell did you go through all the trouble of making a midbass horn with it?  And let me tell your work is not over yet, you are only half way,  when you get rid of the ringing (jajaja), then you are finished...  And let me tell you wont stand the Valencia after that!

Funny choice of drivers,  xovering will be a mess with all the different sensitivities,  the JBL must be 108-110 db,  the Aurum Cantus 102 db,  have you measured what sensitivity you are getting from your upperbass?  Altec 416s I think are around 100 db so you should get 106-108 db if your horn is working properly:  The problem is that you will have to get an amp just for the tweeter (reccomended)  or pad your nice horns down to 102 db (not reccomened)...

Play around with the upperbass horn, then add the JBL and finally tweeter and tapped horn. 

I played around with tapped horns a lot, you must highpass yours at 25-30 hz or it wil become blurry,  plus you have to low pass at 120 hz high order, or even lower to match your upperbass horn; 100- 95 hz maybe,  this will help a lot on transparency.  The cabinet resonates a lot on TH.  Also if you are running it with a subamp, that wont help, most of them are terrible... you might get a nicer one or already got it! 



Posted by Macman on 04-12-2012
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Jorge,

With the risk of being called a moron, I actually didn´t do any calculations more than using hornresp to get a decent spl-curve.

416.jpg

The driver properties a got from a guy in Denmark who renovates old altec drivers. The numbers probably weren´t accurate back in -75 and even less so today. That was what I had to work with anyway, not having the proper equipment to measure the drivers myself.

IMG_0452.JPG

This is what the back chambers look like. The obvious way to reduce the volume is of course to put stuff in there and listen to the results. The lid has 16 screws so there will be some work. Maybe I can come up with a different method though. The easiest way to make the chamber acoustically bigger is probably to add stuffing. After reading about Romys midbass horn I hardly think the volume needs to increase, more likely decrease.

I was thinking of bi amping the whole system so i dont think the different sensitivities will be a serious problem.

Regards
Marcus

Posted by Romy the Cat on 04-12-2012
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Marcus, I have no idea why Jorge assosiated your resonance with your back chamber volume – they are absolutely not related.  Why suddenly you start to talk/think about the back chambers is beyond me. Also, I have no idea what the HornResp does at my sit. The HornResp is a tool for idiots, you probably need to try DIYAudio.com – over there they will gladly embrace the HornResp logic. 

The Cat

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