I cut out almost all the steel for both speakers today, with the exception of the base. that will be difficult to weld on the flat so i may end up leaving it to last and standing the speaker up on the plate before i weld a bead around it.
I only used one 8x4 sheet surprisingly. i was following a youtube bill of material that said 2 sheets was necessary for its larger speaker but no matter.
I panicked when cutting the front and back panels, i thought that there would not be enough room for speaker bolt holes with a 19cm in a 20cm front so i subconsciously used the external measurements. now the front and back panels are 20.6mm wide for the same 22cm overall width. I am unsure if i should go back and shave off the extra 6mm. maybe there will be no appreciable difference with the random drivers i will end up using.
It rained hailstones on me on several occasions while i was working.
I got in contact with the music shop and he said he would look into a driver for me. he said all the non essential businesses he buys off are closed due to covid but will open on the 19th.
I only used one 8x4 sheet surprisingly. i was following a youtube bill of material that said 2 sheets was necessary for its larger speaker but no matter.
I panicked when cutting the front and back panels, i thought that there would not be enough room for speaker bolt holes with a 19cm in a 20cm front so i subconsciously used the external measurements. now the front and back panels are 20.6mm wide for the same 22cm overall width. I am unsure if i should go back and shave off the extra 6mm. maybe there will be no appreciable difference with the random drivers i will end up using.
It rained hailstones on me on several occasions while i was working.
I got in contact with the music shop and he said he would look into a driver for me. he said all the non essential businesses he buys off are closed due to covid but will open on the 19th.
Bob Brines’ early work taking advantage of the leap that the MJK's modeler has provided us. Actual builds confirm its veracity.
As i said earlier, a Voigt gets much better as an ML-Voigt.
dave
The maths of how to design a cabinet is beyond me though. what i like about the voigt pipe is that there doesn't seem to be any complex structure to tune. all you can do is change the driver location. I had a look at my car drivers. they had got wet at one time and the cone got soggy and changed shape. when i was cleaning the moths out of the foam at the rim i poked through in one place. i'm not sure if it's worth wasting time on them as they look like they will deteriorate quickly with use, and the damage i inflicted will only accelerate it.
It is a complex box to tune, if you don’t have the right driver in the right box.
If you pick a driver i am sure that just the talent in this thread can come up with a proper box.
Note that in most ML-Voigt the optimum Zd is 50%. Half way. And i expect a vertical holey brace would be suggested to further push potential resonance sup in frequency and to further stiffen the baffle (and back).
dave
If you pick a driver i am sure that just the talent in this thread can come up with a proper box.
Note that in most ML-Voigt the optimum Zd is 50%. Half way. And i expect a vertical holey brace would be suggested to further push potential resonance sup in frequency and to further stiffen the baffle (and back).
dave
This one?
Or this one? *hmm, i have a single that looks an awful lot like this one)
From this image i know GM has done a Voigt for the latter, what you are tunign is the elimination of the 2 big suck-outs with damping..
I will leave it to the experts but u suspect the former not all that suited to a Voigt.
dave
Attachments
the former. here's the ad, the datasheet dimensions showed it's a lot smaller than it looks. i find it hard to come by a second hand 8 ohm driver, everything on the market is 4ohm for car audio. I wouldn't mind modifying to use a pair of speakers in series like the BIB does but i'd lose the bass if i went smaller than 8 inch.
Speaker Driver Hifi Bass Monacor Super Quality For Sale in Watergrasshill, Cork from bulas
Speaker Driver Hifi Bass Monacor Super Quality For Sale in Watergrasshill, Cork from bulas
Here is one i know and like and can fit a proper ML-Voigt. And there is a freely available design from Scott.
http://wodendesign.com/downloads/Imbolc-ML-V-plan-0v91.pdf
dave
I would if i could. as i mentioned before i do not have access to a credit or debit card so I am limited to what i can buy over the counter or second hand.
I don't wish to use a different voigt design as i cut the steel out today. I would be okay with using a round port instead of the square one, but all the other dimensions are different in the ml voight so it would all be guesswork. the other ml voights use a complex baffle system which is difficult to accomplish in steel. all the holes must be burned with a welding rod as i have no machining facilities and will be inaccurate with size and placement.
I don't wish to use a different voigt design as i cut the steel out today. I would be okay with using a round port instead of the square one, but all the other dimensions are different in the ml voight so it would all be guesswork. the other ml voights use a complex baffle system which is difficult to accomplish in steel. all the holes must be burned with a welding rod as i have no machining facilities and will be inaccurate with size and placement.
At nearly a 1/4" thick, it's extreme 'overkill' for any typical 'full range' HIFI/HT speaker. 10 ga CRS is the thickest I ever used since the cab I 'borrowed' for testing was a 60" W x 90" H x 24" D high voltage industrial motor controls cab. Typically used 14 ga HRSPO or CRS depending on size and galvanized if it needed shielding for closeness to CRT TVs.
FWIW, the plant's welders always tacked assemblies together before any seam welding was done.
I 'feel' your pain. :( Was planning to replace [some more] storm damaged siding and rip out/build a new rear porch as soon as labor became available to help me, but a 4x increase in building materials and 2-3x more in wages means I'll be patching it up with scraps for the foreseeable future. :cuss:
Anyway, as previously indicated/implied, with metal we want one that 'rings like a ten penny nail struck with a ball-peen hammer', then only add some angle bracing on large unsupported panels if obviously required.
Ooh! :) 'Blast from the past'! IIRC it was the first site to post any speaker damping, stuffing test results.
Re choosing drivers, search for specs like the original RadioShack 40-1354: Steven Brown?s DIY audio site
Its Monocor SPH-60X closest replacement: https://www.monacor.com/products/co...logy/hi-fi-full-range-speakers/sph-60x/?r=pdf
You are in Ireland, yes?
You can order from some webshop located in some other EU country, and pay by bank transfer.
Money transfers in EUR currency between EU countries are now cheap and simple. You just need your bank account.
I ordered alot of stuf that way, mostly from Germany.
They have some excellent speakers webshops there.
The bank has updated it's two factor authentication to require either a current gen smartphone or a dedicated challenge response device. I would have to organize a few accounts which is more trouble than i care for at the moment.
I had a difficult bout of psychosis a few years back which I have still not fully recovered from. I do not adjust easily to changes in my routine and when such change is necessary i tend to wait until i have sufficient energy in the summer, or ask a family member to help out. It is painful for me to set up these accounts.
To all of you, please do not post comments asking other users to donate freebies. It's a fast way for me to become unpopular and wholly unnecessary considering I will get something usable over the counter eventually.
I had a difficult bout of psychosis a few years back which I have still not fully recovered from. I do not adjust easily to changes in my routine and when such change is necessary i tend to wait until i have sufficient energy in the summer, or ask a family member to help out. It is painful for me to set up these accounts.
To all of you, please do not post comments asking other users to donate freebies. It's a fast way for me to become unpopular and wholly unnecessary considering I will get something usable over the counter eventually.
I took a closer look on that Monacor SPH-165 driver (the one with black cone and bigger magnet) and I think its a good fit for that Voigt.
SPL response has a 2-3db bump around 300Hz which is good beacuse pipe have a big hole at that frequency, so it will help to smooth things up.
LF rollof starts little before 100Hz which is also good beacuse it will reduce response bump at pipe resonating freq. around 60Hz.
Qts is low, and Fs/Qts ratio is above 100, so TS parameters are suitable for Voigt pipes.
165 mm driver is not too small for this pipe, they were used before and they worked. The pipe internal volume is only around 32 liters so I think 165mm/6.5in driver is actually more suitable than 200mm/8in.
You know this is midbass driver so you need additional tweeter and some crossover.
SPL response is smooth all the way to 5khz, with gentle rollof after that, so you can use natural rollof of the midbass (no crossover) and switch the tweeter in at 5khz with simple capacitor in series with it. Youll have to experiment with capacitor value and tweeter phase in order to get optimal result.
If you dont mind 2-way system that might be simplier solution compared to full-range drivers which usually need inductor-resistor-capacitor filter to get smooth HF response.
Tweeter should have same impedance as midbass, Fs below 2khz and 89-91db efficiency.
Take these advices with caution beacuse, as wrote before I burned myself with that project.
I hope youll make it work.
SPL response has a 2-3db bump around 300Hz which is good beacuse pipe have a big hole at that frequency, so it will help to smooth things up.
LF rollof starts little before 100Hz which is also good beacuse it will reduce response bump at pipe resonating freq. around 60Hz.
Qts is low, and Fs/Qts ratio is above 100, so TS parameters are suitable for Voigt pipes.
165 mm driver is not too small for this pipe, they were used before and they worked. The pipe internal volume is only around 32 liters so I think 165mm/6.5in driver is actually more suitable than 200mm/8in.
You know this is midbass driver so you need additional tweeter and some crossover.
SPL response is smooth all the way to 5khz, with gentle rollof after that, so you can use natural rollof of the midbass (no crossover) and switch the tweeter in at 5khz with simple capacitor in series with it. Youll have to experiment with capacitor value and tweeter phase in order to get optimal result.
If you dont mind 2-way system that might be simplier solution compared to full-range drivers which usually need inductor-resistor-capacitor filter to get smooth HF response.
Tweeter should have same impedance as midbass, Fs below 2khz and 89-91db efficiency.
Take these advices with caution beacuse, as wrote before I burned myself with that project.
I hope youll make it work.
I think i'll pass, seems too complex. while i do have a junk box of oddball resistors they won't stretch to making a crossover.
I have a scrap audi car here and i was told they have excellent bose speakers. i took a look in the driver door but it seems smallish, like a large mug in diameter. i think the rear speakers might be larger, the vents are at least.
I decided to fix the steel measuring issue and cut the front and back voigt pipe panels down to 20cm. it's for the best because the cutting disc wandered a little the first time and this time is more accurate because i have a straight edge from one of the panels to cut against.
I have a scrap audi car here and i was told they have excellent bose speakers. i took a look in the driver door but it seems smallish, like a large mug in diameter. i think the rear speakers might be larger, the vents are at least.
I decided to fix the steel measuring issue and cut the front and back voigt pipe panels down to 20cm. it's for the best because the cutting disc wandered a little the first time and this time is more accurate because i have a straight edge from one of the panels to cut against.
I welded up one of the cabinets today, but left off the front as i will need to grind the inside surface smooth after the driver hole is melted. I am still deliberating on the dimensions for a reflector plate. I think it's not hugely critical though.
I was thinking about what to do with the other steel sheet i have. i saw a mention of the metronome, they look like a bassy instrument without the comb and notch issues. i found a thread with several hundred pages. i'd appreciate a quick run down on the pros and cons of the metronome.
I saw a mention of a quadratic taper. that seems to be terrible for acoustics, but most of these terms are beyond me.
I was thinking about what to do with the other steel sheet i have. i saw a mention of the metronome, they look like a bassy instrument without the comb and notch issues. i found a thread with several hundred pages. i'd appreciate a quick run down on the pros and cons of the metronome.
I saw a mention of a quadratic taper. that seems to be terrible for acoustics, but most of these terms are beyond me.