| Timn8ter |
| I'm going to build the folded version 0.2. I have another t-line project going at the same time so I got three panels cut for the 127 build and ran out of wood. :cannotbe: |
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| roystr |
drawing yet??
im new so im just gonna toss ina guess here.
say i have 2 of the FE127E drivers. how would they work in a "voigt" type of enclosure?? and if that would be fine,is there a size ? or as long as the shape is the same would that get me close enough for some decent sound? i like the idea of one driver,for alot of reasons,one of witch is i have no idea about crossovers yet. my box building skills arent all that good,but i have a table saw,and chisels,a few small palnes,and the pile of miscelanius stuff in the garage.
i sure would like a plan and ive been talking to "timn8ter" and we kinda came up with a toss up between a book shelf type,and i think,something like the voigt. he called it something else though. in fact,he sent me this link and told me it was a long one,but he didnt tell me it wasent finished... hahahahaha
well i feel like i know a few of ya now,after reading this for a few hours.
take care,
roy |
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| Timn8ter |
Hi Roy!
Yeah, I left out the fact that this is very much a work in progress. The design I had in mind for you was this one.
http://www.diyaudio.com/forums/atta...tamp=1102449671
Granted, no one has built it yet but the simulations look very good. Having played around with similar designs I'm confident it will sound quite nice. The important piece that probably needs to be discussed for this one is baffle step compensation. Those who have indicated so far that they are building something are going for the bipole design which needs no BSC circuit. Here are two links that give good descriptions of baffle step compensation.
http://www.trueaudio.com/st_diff1.htm
http://www.quarter-wave.com/General/BSC_Sizing.pdf |
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| planet10 |
| quote: | Originally posted by Variac
Another point is made by the Omega speakers. He sells conventional and bi-pole models. I still think our early idea of having a module that can be used back to back to create a bi-pole, or placed against a wall, or wired different ways is a great idea. I guess it would need to be reasonably shallow, so I withdraw my demands that it be a narrow tower. ;) |
IIUC the omega bipole is 2 monopoles placed back-to-back.
dave |
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| planet10 |
| quote: | Originally posted by william2001
Once I'm able to afford the other two 127's and acquire more ply (and time), I plan to build Dave's version 0.2. |
Tim has to get credit for doing the MathCad sims... i'm just making the numbers into pretty pictures.
dave |
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| roystr |
| im reading as fast as i can. pant pant |
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| roystr |
if what im reading,i understand,the smaller the baffle,the smaller the step. thats why when the speaker gets closer to the wall, the step gets smaller.
is that correct?
if it is,then hows this......
make a speaker like a tall triangle,say 4 feet. the first 5" starting at the top,cut off so the top is flat. then if you layed down the "box" and used the "flat top" part as the baffle where the driver goes,id say thats a very small baffle and wouldnt the "step" be equaly small?? then wouldnt the problem be so small at that point,to be void of consideration??
hey,it sounds fine to me.
back to homework.
roy
Tim, i e-mailed you about the speaker choice i have to make. |
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| planet10 |
| quote: | Originally posted by roystr
if what im reading,i understand,the smaller the baffle,the smaller the step |
No... the smaller the baffle the higher the frequency at which the step happens.
dave |
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| roystr |
that seemed way to easy.
oh well, (yawwwwn) back to the drawing board.
roy |
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| x. onasis |
Well I built the "elegantly folded"VO.2 Makes for a nice shallow bookshelf for a bedroom. I was a little unexcited when I finished it, as I had three projects finishing at the same time, a 3-way using Audax and vintage drivers, and the CSS XBL which really blew me away being so compact and with great low end.
I'll save my critique til the drivers are more broken in. But I had to say this: I just finished the proto Bipole VO.2 on Saturday and after a quick listen, I stopped the process to order some fine black walnut veneer, dragged them upstairs and rearranged the living room for some serious listening. The bipole is another dimension...great bass, a little forward in the upper mids so far, but I understand Tim's earlier remark, "Sure, if you like depth and detail" And BTW, the added 19" for extending the cabinet into a tower works well.
Now onto the Folded N Monopole but I think it's going to be temporary.
Is there a group buy for more drivers?:) |
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| gmilitano |
| quote: | Originally posted by x. onasis
I'll save my critique til the drivers are more broken in. But I had to say this: I just finished the proto Bipole VO.2 on Saturday and after a quick listen, I stopped the process to order some fine black walnut veneer, dragged them upstairs and rearranged the living room for some serious listening. The bipole is another dimension...great bass, a little forward in the upper mids so far, but I understand Tim's earlier remark, "Sure, if you like depth and detail" And BTW, the added 19" for extending the cabinet into a tower works well.
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Well that is a very positive start! What are the dimensions of the port? Do you have any pictures?
Cheers,
Gio. |
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| roystr |
i bet it would be perfect for a beginner. does anyone know if it needs any kind of electronics added to it.like ohm filters,or stuff like that. if i can just build the cab,and wire up the drivers,id be in decent shape. but if it had to be fine tuned,i wouldnt know where to begin.
roy
is there one place on this site where all the plans like the "folded mono pole" are located?? or are they kinda scattered about?? |
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| x. onasis |
I used 2" piece of 2" PVC for the port. Sorry, no pics....I get cold feet at the camera store. Maybe I should try and trade, instead of giving stuff away:xeye: Here's the veneer tho.
roystr- Click on my links above for plans. No filters needed. (And tell Tim to add four drivers for you in the group buy)
:) |
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| roystr |
alot of speakers with that pile. how much would the speakers cost me with the group price by the way??
and why would i need 4?? or would i always get more for the next batch??:-) |
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| x. onasis |
Roy, I was being a little facetious about the group buy. ( I was hoping Tim might organize one) They're $36.50 ea. at Madisound and as I was hinting in my earlier post, the bipole is a significantly different speaker than the monopole, so I was recommending going right for 4 drivers.
I'm a cabinetmaker by trade, so building boxes is pretty easy for me, but I've found that the cost of drivers is relatively small when you factor in all the other materials and your time....especially finishing them. To be honest, I wouldn't build the Monopole , except that I only have a single pair of drivers left, and we're building these as a group project for comparative purposes.
When I'm done with the bipoles, I may have $300 in them, but there's no doubt they'll be far nicer than what twice that buys at the stores. |
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| roystr |
i dont mind 4 drivers,as long as the wife says i can get them. the kids had a way nice christmass,and that means im (my buying habbits are) on a short leash for a while. as im dissabled and dont work,i dont spend to much on myself all the time.and as i told Tim,last summer the wife got me a new motorcycle because she was tired of riding hers alone,and/or with out me. then theres my power tools,,and my shortwave radiop....and,,,well you get the picture.
but i am excited about learnign and getting started with this speaker building. as long as what i get are at least as good sounding as what i could get in the store,ill be more than happy. plus,.its always better when ya do the work your self.
and 36$ is a good price. couldnt we /I put two of the drivers in each folded bi-pole?? for a lil more .......somthing. and i think i read that 2 drivers make them more efficient.
"HEY HUN.....TIM AND ONASIS WANT TO KNOW IF I WANT TO JOIN THEM GETTING IN ON A GROUP DEAL FOR SPEAKER PARTS.........."
HAHAHAHAHAHA
SEE YA,
ROY |
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| x. onasis |
| The plans I linked to are for the FE127E. |
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| roystr |
everything ive read about it,says its awsome. thats good to know. but still,couldnt i use two of them for each speaker ? well i know i could...the question is,would i get somthing out of it that would outweigh using two as aposed to useing just the one.
and if its not worth it, fine,4 of them would let me make two pair of maybe different speakers.
~R~ |
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| gmilitano |
| quote: | Originally posted by roystr
i bet it would be perfect for a beginner. does anyone know if it needs any kind of electronics added to it.like ohm filters,or stuff |
Keep in mind that we are in the early stages, but I would strongly suspect that the monopole would require a BSC as a minimum. A zobel may not required. Each BSC would cost in the order of about $7 - $10. The bipole would not require a BSC.
Cheers,
Gio. |
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| roystr |
to whome it may concenr,,you can put me down for 4 of them FE127E's ,,,,,yeeee haaaaaa. i cant wait to hear them,,and the wood is still at the store..heh heh heh
OH YEAAAH!.
~~R~~ |
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| roystr |
no realy. would a speaker one of us built be considered a single driver if it had one of those non-powered flat looking bass helpers in it? i forget what they are called,they help or assist the regular bass driver.
and if they are ok ,i was thinking again,,,instead of using the through tube in a reflex style speaker,couldnt you use one of them (sheeesh) "non-powered bass helper units ??" that way it would have room to move in and out, letting the air move around inside [[ and maybe make a bit of free bass]] ,but not enough for the air to leave the enclosure entirely,kinda blocking the hole just part way.
hmmm i wish i could remember the names of this stuff...
well thats it for now.
night,
roy |
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| planet10 |
| quote: | Originally posted by roystr
"non-powered bass helper units ??" |
Passive Radiator (aka Auxiliary Bass Radiator) -- PR or ABR. This is a port substitute (with the exception that it adds an extra resonance into the mix)
dave |
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| roystr |
dont ya hate it when that happens?
port substitute,great. but is it a good idea? you say "that it adds an extra resonance into the mix". so how do you know when to put one in? i doubt its trial and error. there must be someway you kinda know in certain ones if it would work or not before putting it on.
im looking at a small tqwt 3ft tall. i guess its ok, it looks like most of the others ive seen. the fella that built it said hes happy enough with it............after 40 hours to get broken in. its funny how bad they are(home built) at first,then slowly smooth out to be listenable,or even great pleasure. must drive ya nuts waiting to see if you built a lemmon or not.i know it will bug me. not that bugging me will prevent me from trying to make a decent one.
roy
its at the bottom of the page.called "little boy"
http://www.geocities.com/agalavotti/tqwt.html |
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| roystr |
what exactly are we waiting to decide next ?? it seems there is going to be several different types/shapes of speakers built.i dont know how many will participate though. about 25 should make it fun. well you think on it.
~R~ |
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| Timn8ter |
| I believe we're just waiting for some prototypes to be built and then we can move on to fine tuning. I'm sorry I haven't been able to get to building mine yet. It's on my list but not at the top. :cannotbe: |
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| SCD |
Hello Group:
I am in the same boat as Tim. I have my drivers on a baffle playing the local FM station right now. I have the designs and a TQWT pipe, I have the material I just need a little time.
I may get a few hours this weekend. I will post once I get something completed.
So many project so little time. Maybe I am sleeping too much again. |
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| roystr |
would ya mind letting me see what a tqwt and a pipe look like? send me a picture or a picture of the same thing if you want,but not the one your building. either way,im curious if i know what it is,but i probly have the names wrong. alot of tqwt, and some different ones with letters like that as well. its like the army..lolnothing has a name,just 3 or 4 letters.
cant wait to get going ,it will be my first speaker set,and im hoping they sound better than the cost of the parts would get me in the hi-fi store.
later,
roy |
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| planet10 |
TQWT = TQWP = Voigt Pipe....
TQW = Tapered Quarter Wave
P = Pipe
T = Tube
A quarter-wave pipe that is small at the closed end & large at the terminus end... driver placed at 1/3 to 1/2 the distance from the closed end....
It has been found that these tend to work WAY better with a restricted terminus (ie ML = Mass Loaded)
Attached is a pic i had handy of variations on the theme (these are based on Tim's bipoler 1197 ML-Voigt).
dave |
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| roystr |
see the pics. or the thumbnails for that matter. i noticed that the other night when i was trolling through the old posts,i thought they were taken down after a while,that was why i didnt see any.
is it like this,if this works im putting up a pic. |
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| roystr |
| but the text says its there. hmmmm(ponder ponder) |
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| SCD |
| I posted a few pics in post # 283, 284. |
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| roystr |
saying there is a pic to click there ,i also see that on my own post,but nothing to click on.
BTW,did you see the pic i posted a few posts back??if you did,what kind of speaker is that? maybe a "back horn" ?? heck if i know. |
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| planet10 |
| quote: | Originally posted by roystr
is it like this,if this works im putting up a pic. |
That would be a backloaded horn (not much flare or mouth thou -- will have limited (& probably ripply) bass.
dave |
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| planet10 |
| quote: | Originally posted by roystr
but the text says its there. hmmmm(ponder ponder) |
What browser are you using? have you cleared your cache? Are you using Windoz and it has gotten plugged up with MalWare?
Pics work fine here.
dave |
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| roystr |
ie as well as firefox. both work as well as can be expected. im gonna go n see if i still have opera.
later |
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| planet10 |
| quote: | Originally posted by roystr
did you see the pic i posted a few posts back??if you did,what kind of speaker is that? |
The joke & the little boy are classical Voigt/TQWT. An ML-TQWT would very likely get better performance out of the same driver.
dave |
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| roystr |
it looks like a demo,you know,to show someone what somthing looks like,but not to scale? i wanted to know what you guys thought if this was a real speaker,and if it is,do you think it would work with FE127 or FE167??? them are the only two i have comming,so if not them two,then ill need another plan. i just think this one looks cool, and interesting. provided it would not sound like a toy.
let me know will ya,and thanx,
roy |
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| Lionel |
| quote: | | i just think this one looks cool |
Indeed, very very nice ! :D
This could be an other thread but...
If you built it "as it" take care to manage a way in the upper part for the wire don't use the TL !
:cool: |
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| roystr |
the "TL"? what is it and where is it?? hahaha
im new so be patient,im learning as fast as i can..
roy |
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| Timn8ter |
| quote: | | If you built it "as it" take care to manage a way in the upper part for the wire don't use the TL ! |
TL = transmission line
In this context Lionel is referring to the pathway from the rear of the driver to the terminus (vent). He is recommending finding a way to not run the driver input wire through that pathway.
A discussion of wire management is always relative to speaker building. As with many things, placement of the binding posts (or not using them at all) is a compromise between the best from a performance view and best from a cosmetic or usability view. From a performance view the best place for the cabinet is question may be on top. |
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| roystr |
i never even thought of that. the wire and the little holes where the leads enter the cabinet/?? nope,it never ocoured to me.
so,how do i route the wires without bringing a harmfull "noise" into the box??( i have a feeling that a simple question does not have a simple answer)..
also Tim, what did you think of that speaker i put out? i said i thought it looked alot like a salesmans "sample" thing he might carry to show his wares,but that it might not be a "real" speaker. what do you think about it? you think it may be real?? if so,id think about building it. but i cant aford to go making somthing that wont be any good.
so what are your thoughts on the lil table speek??
roy |
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| Lionel |
Why my point always seems so difficult to understand ? :bawling:
If you built this speaker with such nice transmission line geometry and transparent sides take care to not ruin your job by putting the wire in the TL, try to hide it ! :D |
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| Timn8ter |
| quote: | so what are your thoughts on the lil table speek??
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| quote: | Originally posted by planet10
That would be a backloaded horn (not much flare or mouth thou -- will have limited (& probably ripply) bass.
dave |
I concure.
| quote: | | so,how do i route the wires without bringing a harmfull "noise" into the box??( i have a feeling that a simple question does not have a simple answer).. |
IMHO, the shorter the distance the better. Also, make sure the wires are not going to vibrate against anything inside the cabinet. |
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| planet10 |
| quote: | Originally posted by roystr
so what are your thoughts on the lil table speek?? |
They remind me of the BK101... something suitable for FE103 or FE83.
dave |
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| Variac |
Roystr
I really like that construction method. I've always wanted to use it, but my speakers are always so big that it would take 20 layers- too much work! Of course the side layers can just be board also-no need for them to be plastic. I thin kthe original comment about the wires was from an appearance point of view.
Hey guys- wouldn't that be a good way to build our reference speaker?
It allows nice smooth radius turns. Costruction is either more or less complicated than box type construction depending on how nice it needs to look! Best way to make it I guess is tracing the pattern on 3/4" layers and cutting the path freehand with a router?
A bandsaw would be faster.- you coulalso use 1.5" MDF as it appears the photo ones are. |
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| roystr |
it was one of them "eureeka" moments for me. i never thought of doing it like that.what a time saver. make one perfect,then just trace it out with a router and make how ever many youll need. all the same ,all perfect.
my first thought was a bandsaw,to cut thicker pieces,but then your tracing a line,with the router,your not tracing a line,your tracing the first piece exactly. the only thing is,how many router bits would you go through???? and would you need a 3HP router?? i think they go up to 3.5. and with the good bits going for 60-90$ each,, if you burned a few up to fast,the cost would skyrocket in no time.
if i had a router,id try it that way.course youd better be sure you have the rite shape first,thats alot of wood and work if after you glue it all up it dont sound good.
that would stink
roy |
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| tleonard |
Having done routing with 3/4" plywood (for a very large desk with a plywood drop lip edge) I don't think power would be a big issue. I did that job with a 2 hp router and REALLY cheap bits and it worked fine...
Anyone else have some experience with this kind of composite layup technique they can share? It seems quite interesting for these kinds of unique shapes. |
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| planet10 |
| quote: | Originally posted by tleonard
Anyone else have some experience with this kind of composite layup technique they can share? It seems quite interesting for these kinds of unique shapes. |
Quite a few have done speakers using the Translam technique.... Andy Graddon has a bit of a gallery -- andy was an early proponent of this tech --
http://users.tpg.com.au/users/gradd...oudspeakers.htm
A number of commercial loudspeakers use this technique too.
It can be very wasteful of material thou.
dave |
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| MarkMcK |
For those still pursuing the FE127E project, here is a prefilter. It is different, probably better, but still far less than hi-fi.
Mark |
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| gmilitano |
| quote: | Originally posted by MarkMcK
For those still pursuing the FE127E project, here is a prefilter. It is different, probably better, but still far less than hi-fi.
Mark |
Hi Mark,
Thanks for the info. How many hours do you figure you have on that driver now?
Regards,
Gio. |
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| roystr |
what does a pre-filter do?
thanx
roy |
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| MarkMcK |
Gio,
While I tested the drivers right out of the box, the response graphs for the FE127E were done after 24 hours of "conditioning" using a low frequency sine wave just under driver power limit. This is the standard break in conditioning in the literature. You can find a cab tuning experiment using this break in procedure in the Loudspeaker Cookbook, sixth edition. Except for the expected decrease in Fs and increase in Vas, there was no measurable difference in performance.
Also, a prefilter attempts to correct problems with a driver or loudspeaker by a complementary altering the signal fed to the driver. Baffle step correction is an example of a prefilter.
I am also attaching a corrected version of the driver with prefilter response plot to this post. When I plotted the data, I used the incorrect time base. The top end response of the FE127E begins to die just over 16kHz instead of just under 20 kHz as shown in the previous graph. All the other points of reference (the peaks dips in response) are slightly shifted up in frequency. Sorry for the confusion.
Now, back to the first paragraph. Since that original period of conditioning, I have driven the driver with broadband test signals and swept sine waves as I attempted to make sense of the TL enclosure designs. There is, however, more number crunching than actual voicing of the driver. This entire process has added only a couple more hours of operation. Far less than the 200 hours that has been suggested in this thread.
What, however, should be the conditioning process for breaking in a driver? Will music break the driver in differently than a low frequency sine wave? If so, how important is the type of music and the level? Someone suggested raggae music would break the driver in faster. But wouldn't the loudness also matter? And since pop music is usually compressed and has a higher average to peak loudness in comparison to classical, wouldn't that mean that it would take much longer to achieve the break in period if you listen to classical?
I am rather skeptical of a 200 hour break in period. Think about it. First, if the driver continues to change over the first 200 hours, what possible reason do we have to believe it will stop changing after 200 hours?
Besides the question of break in period, I also have some questions and concerns about the TL designs posted to this thread. I have built and tested three of the cabinet designs: the cheese wedge for the FE126E, the tall, thin monopole for the FE127E, and the tombstone monopole for the FE127E. The testing and analysis is becoming a huge project with an almost unmanagable amount of data. The problem, however, is that across all the tests the driver and enclosures are not acting as I would expect or predict for a TL.
I would find it helpful if Tim and Dave would explain what they predict their enclosures will do to the response of the driver. What gains will the TL enclosures provide? Are there any negatives? How and where do they expect the enclosures to make the response of the driver better or worse? And lastly, what should the nearfield response from the driver be like and what should the nearfield response from the trasmission line aperture be like?
Mark |
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| roystr |
wow thats alot of information. someday ill be able to read it and understand it.
what im curious about is your referance to TL speakers.. is that the plan for the speaker were supposed to build with the 127? or do we build anything we want as long as its a single driver unit??
and do you have a website so i can see the ones you mention in the above article? how theyr built,what the measurements are,ect..
how did the 127 perform overall? you said you gathered quite a bit of info on the tests. but didnt mention how it turned out. was it (using the 127) a waste of time? sould you have tried a different driver instead?
thanx,
roy |
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| MarkMcK |
Roy,
This is a really long thread and I realize that it can take a while to read it all.
Dimensioned drawings of all three enclosures are a part of this thread. I believe the three enclosures I mentioned appear within the first 200 posts. Further, and only a couple of pages ago, I believe Gio restated the purpose of this thread. As I understood it, it was for everyone to build the same loudspeaker. If we do not, then we really cannot have a common reference sound.
As I read this thread, those dominating the discussion have decided on the FE127E in a transmission line enclosure.
Recently, there have been posts about plexiglass enclosures utilizing horn shaped apertures for the TL. ( Just for clarification, in the historical literature, a horn is a type of TL.) I feel that these plexiglas posts and Dave's latest series of enclosure drawings is providing far too many choices for enclosure when we have no good data on the performance variables of any of the enclosures. But then, that is a common problem with all discussion formats. Talk is always faster than doing.
I am just trying to better understand the intent of the early enclosure designs before I will do anything with the more difficult to build plexiglass rear horn TLs. I also want to hear more detail about the theory and design without being contaminated by actual performance results.
Best,
Mark |
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| roystr |
i know it is,thats why when Tim told me about it, i READ it.
what else about this long thread do you have to point out to me?
granted im no stereo hound,but im trying to learn. |
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| MarkMcK |
Roy,
I don't understand what you are trying to learn? I understood your questions to be about the decisions/direction of this thread.
Mine has only been a very minor voice in the history of this thread. The decisions about the direction of the thread have been made by others. If that was the intent of your questions, then Tim would be the best person to ask.
If your questions were about loudspeaker designing and building, then the answers may not be found in this thread.
For example, you said, "you said you gathered quite a bit of info on the tests. but didnt mention how it turned out. was it (using the 127) a waste of time? sould you have tried a different driver instead?"
By transmission line theory the important variable is the length of the line and the quarter wave length of driver or system Fs. Since there will be some variance of Fs from one example to another of a particular driver, it would seem that there must be some degree of tolerance in the length of line to Fs. As such, another driver with similar Fs may work just as well in the same enclosure design. If, however, the Fs of the driver is not so close, perhaps only a small adjustment in the length of the line is necessary.
If, however, the enclosures presented in this thread are hybrid designs, utilizing variables other than that of a pure TL design, then they may be much more sensitive to driver selection. That is one of the things I would like to hear from Dave and Tim.
So, should I have tried a different driver? I do not know. The dominant voices in this thread have already made a group purchase and have the drivers. For those new FE127E owners at least, the decision of driver selection has been made. With this consideration, my contribution seems limited to documenting the performance of that driver and whatever enclosure is eventually set. While I would not have chosen the FE127E, I did say I would try to help those who did, at least to some degree. Would optimizing an enclosure for the 127 be a waste of time? I do not believe it would be.
If I may be allowed to make a suggestion to the entire group at this point, it would be to start talking to Fostex about improving the cone vibration performance of their drivers. The sound would be much improved and that improved sound available to more people if only the manufacturer produced a better product. It can be done.
If you would want to buy a better 127, write to Fostex and ask them to do better.
Best,
Mark
Let me just add one final thing. If I am a "stereo hound," (or in other words a dog and not a human being), then WOOF, WOOF. :) Of course, dogs do have excellent hearing. |
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| planet10 |
Tim is responsible for the designs, i just turned them into pretty pictures. The designs were generated using Martin king's worksheets and are all ML-TLs or ML-TQWTs (or in Augspurger terminology, TLs with restricted terminus). These seem to be better suited for low Q drivers than a straight TL which likes a higher Q. Results from the MJK sheets have proven to be fairly accurate. The limitation to the design will be the accuarcy of the T/S parameters used (in this case the factory specs). Given that the output of the sheets is dependednt on the things the designer tries out, i am sure there are other suitable designs hiding out there in quarter-wave space.
Fortunately the MLs are fairly tolerant of driver variation, and can be tuned both with stuffing and the restricted terminus (ie port).
All the existing design suggestions are still beta with desgnations less than v1. As input comes in from those building actual boxes further refinement, even different designs, or even drivers may have to be considered. What this thread will contain when we are done -- besides a "family" of related designs (no one design will suit all purposes), is a rich record of the design process, with the option of people taking off on a tangent when they see something of particular interest to us....
I see roystr's comments perhaps leading us toward potential horn designs -- perhaps for the FE126 since it will probably be happiest in a horn.
dave |
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| MarkMcK |
Thanks for the clarification.
| quote: | | Fortunately the MLs are fairly tolerant of driver variation, and can be tuned both with stuffing and the restricted terminus (ie port). |
Explains why they are testing like degraded ported/tuned vented boxes. For the 127, besides the cone loading problems of the enclosures, they can be made to perform much better by changing the amount and placement of the internal filler material.
I assume ML stands for mid line. If it does, then the testing is showing a possible problem with MLs. When fully damped, it is small and therefore probably can be ignored. When fully damped, however, low frequency output is way down. Reducing damping brings up the bass, but also shows much increased magnitude of a spectral repetitive narrow bandwidth dip and then peak. First instance occurs around 400 to 500 Hz.
Mark |
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| gmilitano |
| quote: | Originally posted by MarkMcK
I am rather skeptical of a 200 hour break in period. Think about it. First, if the driver continues to change over the first 200 hours, what possible reason do we have to believe it will stop changing after 200 hours?
Mark |
Hi Mark. The FE127E is my first Fostex driver so I do not know how long break in will take. However, I have read on several occasions that the break in time is in the order of about 200 hours!
Since you have measurements at 20 hours, I think it would be great to get more measurments at 200 hours and compare the two. Since we are all human, I think there is a possibility that after 200 hours, people become acustomed to the sound and say it sounds better.
| quote: | Originally posted by MarkMcK
I assume ML stands for mid line.
Mark |
The ML stands for Mass Loaded.
Keep up the GREAT work!
Gio. |
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| planet10 |
| quote: | Originally posted by MarkMcK
I assume ML stands for mid line |
ML stands for mass loading. The restricted terminus does this. Augspurger showed that the mass loading increases the amount of suppresion of higher order resonant modes (ie increased the performance of the low pass function on the output of the terminus)
| quote: | If it does, then the testing is showing a possible problem with MLs. When fully damped, it is small and therefore probably can be ignored. When fully damped, however, low frequency output is way down. Reducing damping brings up the bass, but also shows much increased magnitude of a spectral repetitive narrow bandwidth dip and then peak. First instance occurs around 400 to 500 Hz.
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The position along the line of the driver is used to cancel some of the TLs ripple. It properly positioned it will almost completely kill one of the harmonics -- usually one goes after the 1st undesirable one because it has the largest magnitude. In an ML-TQWT this is most often halfway. On an ML-TL is is usually closer to a 1/3. Tim has choosen 1/2 in this design. For folding it is quite convienient -- especially in a bi-pole.
dave |
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| Timn8ter |
ML = Mass Loaded, a term coined by Martin King for his work on a restricted terminus quarter-wave pipe. I chose to use Martin's MathCAD worksheets because of it's availability to everyone on this forum and for the accurate modeling it can produce. This also gives everyone here the opportunity to try out the worksheets for themselves using the numbers provided and hopefully offering new and better ideas.
Dave's T-line website, Martin's Quarter-Wave website and G.L. Augspurger's articles for Speaker Builder are excellent places to do some reading on the subject.
My primary goal when using these tools is maximally flat bass response and good phase response while attempting to reduce harmonics in the pipe, in particular the third, first by driver placement then with stuffing.
Secondary goals may include the visual impact of the enclosure and ease of construction. |
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| Timn8ter |
| Don't ya' just love overlapping posts! ;) |
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| planet10 |
| quote: | Originally posted by Timn8ter
Dave's T-line website, Martin's Quarter-Wave website and G.L. Augspurger's articles for Speaker Builder |
Don't forget Bob Brine's site http://geocities.com/rbrines1/
The best version (subtly) of Augspurger's paper is the revised one published in the AES journal.
dave |
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| MarkMcK |
Here is the first of several posts about the test results.
The first set of graphs show the interaction of the enclosure with the driver. That interaction continues up until about 4. 5 kHz. Please do not overreact to the results. All enclosures interact, even open back baffles with wings will interact by backside loading the driver diaphragm.
I suppose one thing to take from these tests is that stuffed or not stuffed, the sound of the loudspeaker will be a combination of the driver and the enclosure. A lot of the interaction goes away with stuffing, but not all.
Good designing and good building,
Mark |
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| MarkMcK |
| This next set looks at the impact of the vent or open aperture on the driver response. The comparison is between the vent closed or open. |
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| MarkMcK |
Today's last post shows the far field, free space response of the loudspeaker comparing vent closed with vent open. The results shown here are repeatable, yet the differences shown are at the low frequency resolution limit of my chamber. While I believe the loss of low frequency output is a function of the loudspeaker and not the test set up, I have little confidence that the amount of difference shown is an accurate reflection of the actual acoustic performance. It may be less or it may be more. The magnitude reduction seen with vent open is likely a notch or dip with the response rising again at even lower frequencies. Few testing labs have the far field low frequency resolution to get the desired detail on this phenomena.
Mark |
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| planet10 |
Without fill, all the enclosures should be showing some ripple... did Tim ever give a specified amount of stuffing (i remember putting ??? in the drawings when i indicated it -- 0.25 to 0.5 lbs/ft^3 is fairly standard)
Unfortunately the linear scale charts make examing the LF results almost impossible and remove any easy way of seeing the periodic pattern any ripples make. Can you repost the results with a log scale?
dave |
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| Timn8ter |
| quote: | | did Tim ever give a specified amount of stuffing |
IIRC, I used .25 lbs per cu. ft. I usually don't go much higher than that. |
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| MarkMcK |
Dave included a fill spec for the tall and narrow enclosure.
I followed that for the tall and narrow and the round top. Now, while some claim that we hear log, multiples of frequency; quarter wave, half-wave, and so on are linear.
The multiplicity of frequency is much easier to see lin than log.
The enclosure interference is not particularly worse than it is for many other enclosure and driver combinations (and I suggested you not overreact to the ripple seen in the 20 kHz bandwidth testing). Most of it, however, is internal and not baffle step or baffle edge.
You can see that in this last post. This last set of graphs shows the response with the last prefilter design. This design is much more complicated than it looks since it takes advantage of filter interaction and prefilter to driver interaction to do more than the mere sum of its components. This is the best I can do. The better route is a new cone design, but that is best left to Fostex. Ask them for it and maybe they will provide.
I have a tendency to discount anything that does not come up to a fairly high standard of performance. I have to remind myself that this is a driver that costs less than $40 USD. No reason anyone should expect perfection for less than $40.
I am not going to break this driver in anymore. I have already put 26 hours at extremely high drive levels. If you compare the stress of my conditioning period to listening to classical music, it would come out to playing music at maximum driver levels at 10 hours for every one hour of conditioning. I will await those that believe in 200-hour break in periods to show us how the driver changes over that time.
Anyway, with this amount of break in, in the round top enclosure and divided body, I found the best bass sound was achieved stuffing one half of the body with the specified amount of fill and using 1/4 specified amount to loosely filling the half with the port.
Fully filled or filled as described above, the loudspeaker produces more of a suggestion of bass than actual bass. Whether fully filled or filled as described above, the speaker has a slight tubby sound. Often described as the oatmeal tube sound. I have heard worse, but it is audible. The upper mid bass and lower midrange is slightly dense, not open or airy. On complex music, it becomes a wall of sound noticeably lacking in detail and clarity. The upper midrange and treble has a dry edgy sound. I dread using this descriptor since it does use a paper cone, but it is a dry papery sound. This is especially noticeable on sibilance and second and third vocal overtones. High treble remains a little smeared or splashy.
With this prefilter, the response is tamed enough that you can actually hear the sound of the speaker. Since the component sizes are small, the cost of the prefilter is small. Whether you like the sound of it I will leave up to the listener. If you don't there is less lost on the cost of the prefilters than on the Madisound cost of the drivers.
All in all, it is an okay design. Well done people.
Good designing and good building,
Mark |
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| planet10 |
| quote: | Originally posted by MarkMcK
I followed that for the tall and narrow and the round top. Now, while some claim that we hear log, multiples of frequency; quarter wave, half-wave, and so on are linear.
The multiplicity of frequency is much easier to see lin than log. |
????
The ripples should show up on a log graph as relatively equally spaced peaks & suck-outs...
On the linear charts to 20k all the info of interest is crammed into the leftmost 5% of the chart.
dave |
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| moray james |
| just a photo of a cabinet design (one of a series) which shows the general idea of a cabinet in which currently resides a fostex fe126e (has also run with fe127e). I am currently also running a fe166e in a larger version. Excellent results. The chief benefit of this design is that it effectively loads both the front side and the back side of the driver which yields excellent control of driver motion while permitting a good air impedance match between the driver and the air in the room. Size is compact bass response is superiour to a ML TL and dispersion is superb. Hope that this generates some thought. Best regards Moray James. |
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| planet10 |
Good to see you here Moray ... how's the snow in Calgary?
dave |
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| Brett |
| quote: | Originally posted by moray james
just a photo of a cabinet design (one of a series) which shows the general idea of a cabinet in which currently resides a fostex fe126e (has also run with fe127e). I am currently also running a fe166e in a larger version. Excellent results. The chief benefit of this design is that it effectively loads both the front side and the back side of the driver which yields excellent control of driver motion while permitting a good air impedance match between the driver and the air in the room. Size is compact bass response is superiour to a ML TL and dispersion is superb. Hope that this generates some thought. Best regards Moray James. |
Very interesting design Moray. Have you done any FR measurements for it? Interested in both how the TL improves the response at the bottom, and the effect of the Karlson coupler in the midbass and up. |
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| moray james |
| Hi Dave/Brett: fine sunny day here on the Bow. As I said I do not have any measurement gear right now so only my opinions. I did build a ML TL (0ne for the fe177e and fe127e)for these drivers when I started this to have as a reference. The K-Lines have bass that is just as deep but with far more impact than the ML TL's. The sound stage and image is as good as I have ever had perhaps better. They can cast up the kind of stage which seems to superimpose the recording venue over top of your listening room which can be strange with a good recording as you find yourself feeling as if you are not listening in your own room. Well worth playing around with. Regards Moray James. |
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| BigDog |
Moray, the speakers that you showed pics of , do these have plans or a web site, I `m looking at several speakers and these lookvery good. I built the Martin King MLTL and would like to try something else too.
Thanks Greg |
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| noisenyc |
| quote: | Originally posted by BigDog
Moray, the speakers that you showed pics of , do these have plans or a web site, I `m looking at several speakers and these lookvery good. I built the Martin King MLTL and would like to try something else too.
Thanks Greg |
check this:
http://home.planet.nl/~ulfman/ |
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| moray james |
| Greg: I do not have any plans published yet. I am still working on tweaking the design on a seties of drivers. When I get there I plan to publish the designs for others to use. I am more interested at the present in working along with others who may have ideas to further the design. I think that the pictures show enough for someone with the skill to pick up the ball and run. The project is not ready yet for a how to discussion on an assortment of drivers. Hope that this helps some. regards Moray James. |
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| BigDog |
| Blackie, thank you for the link. Moray, thanks for the reply and I `ll keep and eye out on this project. BigDog |
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| SCD |
Hello Moray:
Very cool design:
I think I have it figured out. You appear to have taken the principals of the Karlson and the MLTL and come up with an interesting hybrid. Excellent idea, very innovative combination.
Thoughts:
The back wave could be tuned and a port included to vent into front portion.
Another option may be to make the back portion of the enclosure into a TQW line. The challenge will be to get the driver as close to the middle of the line as possible.
It looks like this discussion needs a home of it's own.
Good for you |
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| moray james |
| SCD: the back wave line is a 1/4 wave TL and the terminus of that line does infact terminate into the front Karlson coupler. This is about as close to a free lunch as it gets. The increased load to the driver and improved impedance match to the air in the room are proved by the fact that a driver in this design has greater impact and output as compared to the same driver in either a ML TL or a reflex box. Even at high level output the driver motion is very well controlled far better than in any other design that I have ever tried. All the best for now. Regards Moray Jamesl |
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| moray james |
Here is the content of a post from earlier today at the fullrange driver forum. I hope this spawns some investigation here. Karlsons and thier varients have a very poor response from those who have never tried them. I think perhaps that it is thier strange look combined with the fact that few appreciate just how the Karlson coupler radiates. Most seem to think that there will be huge difraction problems. This in fact is not the case. The tapers on a Karlson coupler act as a broad band resonator acting over a wide range of frequincies unlike the verynarrow band of resonant augmentation provided by a resonant reflex vent or port. The Karlson coupler augments output more in fashion to that seen in a horn design. These qualities are most welcome when using a fullrange low xmax style driver.
The cabinet shown is an early version designed for a fe127e Fostex driver but would also suit an RS 1197 or similar driver. The back line is equal to the driver Sd (cross section) and is approximately a 1/4 wave TL. The driver baffel is only as large as necessary and the line terminus again equals driver Sd. The height of the ellyptical reflector is equal to the driver baffel height (vertical above the terminus opening). You will have to play with different taper curvatures to see what works best. Damping is also critical to make this design work well. Only damp the line not the coupler. I have found that felt damping (1/4 inch) works very well and keeps the lines fundamental resonance strong while damping upper frequincies inside of the line well. Overall damping of the lines Q can be achiever with dense fiberglass or open cell sponge foam at the terminus of the line. A higher aspect cabinet is better for bass than a squat design but I think that at least an inch on either side of the driver is a good idea so that about sets the parameters of the design for you. Somebody have at it and get back to me with any results or clever ideas. All the best Moray James. |
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| Stocker |
...I get the impression then (needs further study obviously) that this K-coupling still needs a long line in the back for deep bass, which would dictate a high aspect cabinet indeed for a small diameter driver.
But the photos of these boxes that I have seen look like they have *short* lines...
What gives? |
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| moray james |
Stocker: the line is approximately a 1/4 wave line, so it's length will be determined by the driver (parameters) of choice. Lower Fs longer line. No free lunch there unfortunately. Longer lines (than required) will not produce deeper or lower bass in fact a longer line will reduce bass output and make the cabinet larger and more difficult to build than is necessary.
The photo shown, was as mentioned, an early prototype. The driver had an Fs of about 80 Hz.. No smoke or mirrors here. You get what you design. A driver with a 70-80 Hz Fs yields a very compact enclosure with good efficiency which will mate to a powered sub very well. Why build larger cabinets than necessary to get the job done especially in a HT system where size is almost always an issue? I think that the Fostex ff85k would probably make an excellent monitor when combined with a mono or stereo sub set up. The small cabinet size insures excellent cabinet rigidity from standard materials. A high aspect K-Line sub would make a great stand for such a small monitor.
Thanks for the response and the questions. I hope that these answers help to clairify things. All the best regards Moray James. |
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| Nanook |
Was there an Aria in your past? Or a Meitner perhaps? Or a Paddy, 7th Ave, and a Mr. Oshiro from Coaldale? Email if ya get a chance.
stew |
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| planet10 |
| quote: | Originally posted by Nanook
Or a Meitner perhaps? |
There is at most 1 degree of separation from Meitner... i 1st ran into Moray via Bill Perkins
dave |
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| planet10 |
Stew,
My reply to your email is bouncing "Mailbox cannot receive mail."
dave |
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| Nanook |
dave:
(again) to reflect my "new" email addy.
stew |
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| miguel2 |
Is the Karlson design suitable for subwoofer applications?
Miguel |
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| GM |
Being basially a bandpass design, it is especially well suited for sub duty IF a suitable driver is used and is made large enough. At a glance, an Avalanche 15" in ~9.2ft^3 net looks good to below audibility.
GM |
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| planet10 |
Today someone asked if my FE103/40-1197 phase plugs would fit into the FE127.
So i was oblidged to do a dustcapectomy... after a bit of a struggle getting some errant bits of dust cap out of the gap....
The FE127 has quite long voice coil that extends quite a bit beyond the apex of the cone. The 103/1197 phase plug is the right diameter but i think needs about 9-10mm more "shoulder".
It was interesting to see some ripples in the out-of-the-box impedance curve disappeared with the dust cap removal (some came back with the too short phase plug)...
dave |
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| planet10 |
dotted line is with no dust cap... fresh out the box
dave |
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| moray james |
| Cool Work Dave: could you do a couple of other plugs for comparrison? I was thinking about a short cylinder with a large enough diameter to mostly fill the voice coil former and then mount a sphere on the end about the size of glass marble the kind we used to call "boulders" (smaller than a ping pong ball). Also could you go to your local hardware store and get one of those miniture spot lights with the mini base? They look kind of like a flat door knob. Don't know if you ever saw but Beauhorn use a shape like that in one of thier Lowther horns. Would be cool to see what they do to the plots as well as to the precieved quality of the drivers top end. The fe127e could use a bit more sparkle in the top end. Best regards Moray James. |
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| planet10 |
Good ideas Moray... i'm always looking for found items that can be repurposed...
dave |
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| paulb |
Apologies in advance for not reading all the pages in this thread, but would it be possible for someone to summarize the status? I'm interested in this as a someday project, but after scrolling back many pages I'm not sure where it's at. Has a driver been settled on yet?
I'm thinking about a FR project, particularly after an article in the latest audioXpress using a Fostex FE103. The author at the end mentions another design that I'll have to look into.
PaulB
p.s. Hi Moray, that was you I talked to on the phone a few months back, right? How are things? Bow thawed out yet (don't get down there much)? |
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| moray james |
| Hey Paul: you are close at hand so if you would like you can come over and have a listen to what I have veen doing with the Fostex fe126e as well as the fe166e. I also have a set of fe207e's in a Martin King MLTL cabinet you can listen to. Have not yet got the JLH amp boards installed into the case but soon I hope. Best regards Moray James. |
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| planet10 |
Since Chris sold his FE108ES B-Horns, and is holding off on the FE168ES, we decided that for the interim it would be a good idea to implement the straight bi-pole so he has something to listen too...
we did a few mods to the existing v0.2 to accomodate the particular situation, here is the plan... called v0.3cb.
Changes/implementation details:
1/ aspect ratio is slightly changed to make them narrower & deeper.
2/ sides extended to meet the floor (ie built-in stand)
3/ ported out the bottom
4/ port moved "outside" the box, ends flared slightly, length increased a bit to compensate (and convienently the same as 3 stacked pieces of 3/4" material)
Will be built with BB + MDF for the base & the extra bottom thickness (choosen for its extra mass to lower the centre of gravity)
dave |
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| Kent Smith |
| I agree with PaulB, would someone like to suggest a reference driver at least? Maybe a mid-size one that provides a ballance between bass and highs, and is not too expense. Something that would be a good starting point for those of us that have not built a single driver fullrange? |
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