Advanced folded Voigt pipe design

[@majtextwriter1794]

Like 2 weeks ago I finished my 1st Voigt Pipe with Mark Audio 4in or 10 cm drivers Pluvia HD. The room's longest side is a little less than 5m, so I made it 150cm tall, 22 cm wide and 30 cm deep at the bottom. The Bottom "bass mouth" is 10 cm high and 18 cm wide = 180cm2 in total. At the end the best measure for my ears is cca 6 cm height of this mouth, so cca 108 cm2 in total.Its volume is cca 32 litres. 24 lit. would be ideal for 4 inch driver I suppose regarding some data, but I am planning later on to install it and experimenting with 5in and 6in drivers, also from other producers. Damping: - true thick sheep's wool felt along front and back panel which are made from 3 cm spruce, - industrial foam 3 and 5 cm thick interchanging on each 10cm on the sides from 2 cm spruce ( this two sides i will make them 1 cm thicker - the sounds of string instruments and voices is not just right)- top 1/4 synthetic wool No binding posts, just pure 4mm copper lice cable directly connected to the driver. I did break in the drivers weeks ago for many hours. I was sooo pleased with the sound, especially surprised with the amount and quality of very nice articulated and fast bass, I decided to make "another voigt pipe" just as a 24 litres folded VP speaker. I made it for a test from old 2cm thick furniture flounder panels, just to see/hear if the box will work fine. I put it together with silicone + crews, so I can disassemble it. The front panel is a 3cm spruce. The folded VP speaker is 95x18x26cm (2/3 of top side is angled down) with pipe folded to the back side - as it is shown in this video by Janoš - because this direction is also for me more logical - better. The bottom mouth is the same one (10 reduced to) 6x18cm and I just made quick (but good) dampening with material left from the 1st pipe and... it also sounded great for such a quick made speaker. Yes, the sound of these 2cm thick flounder panels is not great, but still good enough that you can have an idea of the potential of such a design. It took me cca 1 hour to find the right spots for both speakers in my acoustically treated room. The room is cca 4,6x3,8 m and the speakers are 2,4 m apart and the front panels are cca 80+ cm from front wall, listening position is also like 2,3 m from the middle of the speakers. The speakers are angled toward listening position, but each one a touch different - due to room acoustic and different acoustic properties of speakers. I did not find them sounding great, especially not in a sense of a great soundstage if they do not have a room to breath - also appropriate distance in between the speakers. This is also important also how the bass energizes the room. Despite small drivers the speakers can produce a serious bass when is on the recording, the bass notes are fast, controlled - fast dacay, well articulated and the speakers are not boomy at all. The bass guitar, double bass or drums sounds ad they should, especially regarding a small drivers. So they can play well down to 45 - 40Hz and than rolling off gradually. Max avg loudness before audible distortion is cca 80 - 82 dB. My guess is that 6in fullrangers in this boxes, especially in 32 litres version should/could produce even a quite punchy bass but not in a bassreflex manner. Overall as a pair of speakers with 4in drivers the sound is great, quite balanced one, not perfect, but better than many speakers out there. The only caveat is, It is a bit on a lean side in general (but it it also depends on recording) and a little shouty with bad recordings for now ( you can not expect miracles with such small driver and for me most speakers/systems do sound more or less lean - compared to live instruments and this drivers are a bit special, have a rise in a mid range- designed for Asian market for their traditional singing), but even at this developing point the sound is very alive, fast, lots of details, nuances, great sound stage and the bass is energizing the room on most pleasant way - so the bass, the music sounds as it should sound. And you do not need some fancy power plant amp, just a good source and decent amp. The good/right source - recording or device - is necessary with these drivers/speakers... I would agree that with this driver a decent A/B class amp is the most optimal option. My A class amp is simply too much - too much open in mids and highs and brings so many details (it is simply too good) that is a bit too much for this class of driver on a very affordable side - 110-120 Eur per pair (depending on source and shipping). Last month I had a chance to listen to KEF R3 Reference speakers ( 9K Eur pair) with a Moon streamer -dac and amplifier, a total worth of system over 30k Eur + expensive cables and... I was looking forward to hearing this Kef's regarding the reviews it has on YT, but... I was disappointed. Especially with ambient presentation capability and mid- highs. This my modest system is simply a better, more alive, more natural sounding one. And there is room for upgrading the quality of the sound with cabinet and drivers characteristics. Of course I also have a 20+ years old Marantz CD player with a 1547 dac chip which is still in the category of great Philips natural sounding generation of 1540's series of chips. So I will do a VP pair and pair of VP's folded speakers in a future and do experimenting with 4-6 inch drivers.

[@danrussell9357]

Thanks for answering viewers' questions. Your "Voight Pipes for Dummies" is one of my favorite videos on the channel.

[@realworldaudio]

Thank you Dan!!! :)

[@brucermarino]

Janos, thank you for another fine presentation. I suspect the reduced clarity of the mid-range in the shorter versions can also be caused by: (1) Having the internal partition right behind the driver. This would cause an area of chaos in the air flow that may reflect through the cone. (2) Having the back of the cabinet reflect toward the cone but also add confusion through the driver. Neither of these conditions are found in the toll pipes. Moving the driver lower so it sees only the angled aspects of the internal partition and rounding the cabinet around this partition for less chaotic air flow may help. At the light to wake up to this :) Thank you again my friend.

[@GuitarSlinger60]

Many, many thanks for that video Janos - very succinct - it certainly reinforced what I suspected (and added a few additional factors I hadn't really considered)! Looks like I'm in for a few more builds now, and will take your advice (elsewhere) in respect of initially keeping access to one side of the cabinet for fine tuning. Initially when I did the paper exercise, it looked to be the case that putting the point to the rear would make that section longer, and therefore be like pushing the driver position lower down the effective pipe length, and I wasn't sure on how that might impact it's performance! BTW, Ted (our ginger cat) says hello - couldn't stop staring at your two when watching the other video on our TV!

[@HoomanR17]

Nice video Janos. I'd love to see in one of your videos a close up of the holes on top of your voigt pipe just to get a visual sense of what you're talking about specially if you're happy with them.

[@hugobloemers4425]

Hi Janos, this is a great video that touches on many aspects of the Voigt pipe. There are a few things that come to mind that would be interesting to hear your opinion about: How to tune the vertical position of the driver; What about your folded design, slanted divider to the bottom but move speaker to the back, i.e. opening is firing to the opposing side; Upward firing opening; Karlson type opening, the thought being to create a higher band-width base response. Thanks again :) PS, I like the idea to have holes on the thin end, I was thinking about wedge sized bracing in the tip, dividing the volume in the tip in two or three sections. (As you mentioned in the past, musical instruments also have strategic bracing going on.)

[@NickP333]

Hey Janos. Thank you for this video. I’ve still got most of what I need to build speakers with that old alnico 8” and the compression driver. I like your idea of folding it backwards as well. Just makes a bit more sense, imo. If cutting the last 5” of the top of the Voigt pipe works in theory, then shouldn’t one be able to also do that same thing internally to let the high pressure zone breathe a bit with a folded design? What about another small slot port in the back instead of cutting 5” off? There’s so many things one can do with this design and shape to create the sound one’s looking for. Sorry, one more thing, do you believe it’s better to mount the compression tweeter above, below, or outside of the cabinet like you did on your VOL design? I could even add another driver, maybe a 10”, but I also don’t want the crossover getting too complicated. As of now, the only thing between the driver and tweeter is an L-Pad which I’ll only use to set the resistance then add a resistor after measuring my preferred sound. Now that the weathers getting nicer I’ll hopefully have the time to build the speakers. It’s also a project I can do with my father, which makes it even more special to me.

[@rolandBar]

What do you think of frugal horns? In my point of view it is a folded voigt pipe with an exit on the back. Thx for the videos

[@germangesse8233]

Hello Janos! Thank you for your work! I have a question... In your explanations of Voight's pipe, you consider the lateral projection of the column - a triangle. But if we look at the speaker from the front, we see that the side walls are parallel and the re-reflections of the sound wave behave differently. Is this a problem? If yes, then how is this problem solved? What happens if you make the side walls of the column at an angle? So that the speaker looks like a pyramid on all sides?

[@patrickgrantham8800]

Janos, I really like your explanations of Voigt Pipes. I have a question. In the examples in this video the position of the driver changes. In the straight pipe the driver is central. Folding the pipe backwards (narrow section at the back) the driver is nearer the bottom. Folding forwards the driver is nearer the top. So what effect does this have, or is it not important?

[@Jo_S_999]

Thanks for this video. It was really helpful. Should we try folded pipes with no stuffing, or minimal stuffing? Maybe just a little stuffing in the taper and the part of the panel directly behind the driver?

[@GuitarSlinger60]

Also - on the basis that you suggest that the wave propagation within the (folded) tube bounces from one end to the other, should then the top panel actually be angled (not flat as shown) so it is perpendicular to the centre baffle to give the best possible assistance to the bouncing waves?

[@toeknee8481]

Thanks Janos, am thinking of doing full size, looking at the cube or sonido drivers. Browsing the web searching for other potential drivers and found AER loudspeakers , I see that they are over 2 Tesla and over 100db efficiency so thinking someone may be interested in using them , very expensive but a small second hand car price not a new car price....

[@realworldaudio]

Actually, the cheapest AER driver costs x2 as much as the Cube audio does, and x10 as much as the Sonido. :( The Sonido is very affordable, and their ferrite version costs half as much placing it into the explicitly cheap driver category. AERs go from E2800 a piece to E170.000 a piece! :( Makes Cube audio drivers look like they are made for homeless people in comparison :(

[@Thiago_S..]

@@realworldaudiohi Janos, actually now that cube audio discontinued their entry level drivers, the cheapest I see in their website is E2800 which is the same price as AER BD1.

[@linandy1]

Have you considered a combination Voight pipe with a tuned reflex port ?

[@asadabbasmirza9519]

Can voight pipe be made for or folded one for 15 inch and results???? Better than oaken? Any experience?

[@ThePerkri]

Damping and stuffing in the peak of a pipe is critical in controlling the high frequencies. I would be concerned about the holes you are suggesting to drill at the peak, to whistle, and create noise that is perhaps not wanted. The peak of the pipe can be at either the front or rear, without compromising the line length by simply making a rear slot. The BiB enclosure is kinda like a folded pipe, only different. It’s a 1/2 wavelength.

[@GuitarSlinger60]

Hi Janos - just another thought - do you aim to keep the depths (baffle end-to-front panel / baffle end-to-lid / baffle end-to-rear panel) all the same dimensions, or give a slight increase in dimension from narrow-to-wider parts (as the wave goes around the baffle end)? Seen it done differently in different designs!?

[@fullranger3435]

I find your description very puzzling.

[@GuitarSlinger60]

Basically I'm just clarifying the final position of the inside end of the internal baffle (located behind the driver) - some designs have clearly taken the view that the pipe still needs to taper as the void progresses around the top of the panel, so, the distance from the free end of the baffle is (in this case) greater (slightly) to the front baffle, than it is to the top panel, and less again to the back panel (whereas some designs have kept these three distances equal)!

[@GuitarSlinger60]

This may be a result of the designers either believing the waves flow around the end of the baffle (back and forth from front to rear area say), or, if they believe they deflect off the top baffle..

[@GuitarSlinger60]

Janos clearly explained that for the folded pipe, you simply take the straight pipe, cut it in half and fold it back on itself, but that's not all is it, what you then do is add an additional area above those 'folded' volumes to connect them - so the volume you create in a folded pipe is a little more than just the two parts cut and folded back on themselves - so just clarifying if you continue the 'taper' within the additional space, or, ignore it and keep it all the same dimensions as the area where you (theoretically) cut the pipe to fold it!?

[@fullranger3435]

@@GuitarSlinger60 you are right, the bending results in equal volume only if the corners are rounded, following a circle with its center at the uppermost point of the internal partition and radius, the distance of this point to the inner side of the front baffle. But perhaps it's better to leave it with a little extra room to facilitate pressure deployment at this sharp turning of the wavefront.

[@linandy1]

Have you considered a combination Voight pipe with a tuned reflex port ?

[@realworldaudio]

Yes, and have built several of them. The Voice of Lancelot and the AO are both folded Voigt pipes with tuned reflex ports. It helps to lower the LF extension beyond the reach of the pipe length, for both cabinets I use the port to extend about 1 octave lower than the pipe length would allow. As the AO is really small, it works to make it reach down to 30Hz, and in the case of the VOL to make it reach down to subsonic range (port tuned to 17.9Hz, starts to open below 30Hz, cuts off at 11Hz).