Hi All,
For a bit of background info I used to run a pair of Labhorns in my lounge, until I started building horn mains and needed the space for them.
To my ears they gave the best quality bass I have ever heard in my room. I used them for a while for home theatre with 3x sealed 15" tempest subs running 15Hz-30Hz. Worked well. (the tempests never really sounded great to me above 40Hz)
Since removing the labhorns I've been using the lab12 drivers in multiple boxes as subs.
I recently went back to my 80Hz midbass horns (similar to Edgarhorns) with my 2 way MEH horns above, and whilst setting up the horns decided to try and EQ the Midbass horns flat to 35Hz. (These are for normal hifi / home listening levels, not home theater)
To my amazement they took the EQ and did not sound distorted at the loudest levels I listen to my music at.
I'm hopefully going to have a dedicated theatre room soon, and would like to get back to having horn loaded subs. My Labhorns were horn loaded to 32Hz, and I would go back to them except I would have to A: build 4 new boxes and B: buy 4x lab12 driver (approx £850)
Thinking that 4x labhorns would in reality be way too much output for what I will need, and not having a spare grand to spend on drivers I started looking for alternatives.
I went back to the Thunderbolt cab that Freddi had recommended to me a long time ago. This models well with the EVM15L drivers that I already use in my midbass horns (and will be spare once I build my next MEH project) and 4x cabs will allow a multiple sub setup to even out the bass. They have enough excursion to get down to 30Hz at home theatre levels, and I will run my 4x lab12 drivers in a big 4th order BP to cover 15 - 30Hz to fill out the bottom octave.
There's not a lot of info on the web about the Thunderbolts, except 1 drawing that is meant to be very accurate, some dimensions posted by TB46 (1220mm x 810mm x 640mm) back in 2011. There's also a Hornresp model by jbell on some old threads here.
Rob.
For a bit of background info I used to run a pair of Labhorns in my lounge, until I started building horn mains and needed the space for them.
To my ears they gave the best quality bass I have ever heard in my room. I used them for a while for home theatre with 3x sealed 15" tempest subs running 15Hz-30Hz. Worked well. (the tempests never really sounded great to me above 40Hz)
Since removing the labhorns I've been using the lab12 drivers in multiple boxes as subs.
I recently went back to my 80Hz midbass horns (similar to Edgarhorns) with my 2 way MEH horns above, and whilst setting up the horns decided to try and EQ the Midbass horns flat to 35Hz. (These are for normal hifi / home listening levels, not home theater)
To my amazement they took the EQ and did not sound distorted at the loudest levels I listen to my music at.
I'm hopefully going to have a dedicated theatre room soon, and would like to get back to having horn loaded subs. My Labhorns were horn loaded to 32Hz, and I would go back to them except I would have to A: build 4 new boxes and B: buy 4x lab12 driver (approx £850)
Thinking that 4x labhorns would in reality be way too much output for what I will need, and not having a spare grand to spend on drivers I started looking for alternatives.
I went back to the Thunderbolt cab that Freddi had recommended to me a long time ago. This models well with the EVM15L drivers that I already use in my midbass horns (and will be spare once I build my next MEH project) and 4x cabs will allow a multiple sub setup to even out the bass. They have enough excursion to get down to 30Hz at home theatre levels, and I will run my 4x lab12 drivers in a big 4th order BP to cover 15 - 30Hz to fill out the bottom octave.
There's not a lot of info on the web about the Thunderbolts, except 1 drawing that is meant to be very accurate, some dimensions posted by TB46 (1220mm x 810mm x 640mm) back in 2011. There's also a Hornresp model by jbell on some old threads here.
Rob.
So I found a really good website that converts Jpegs to DXF files. I could not believe the quality of the file it put out when I loaded it into CAD.
Once scaled there were 2 immediate problems - the cab scaled to 1220 x 820 (not 810) and the wood thickness ended up being around 30mm (~1 1/4") !
I went with the 1220 x 810 outer dimensions and worked out centrelines for all the flare pieces, converting to 18mm (3/4")
I had to shift the position of the 2 pieces that form the throat by 3mm each to get them to touch each other.
I then put in a centreline to get the lengths worked out for the hornresp model. I looked up 'advanced centreline method' but so many long winded posts and a general consensus that it did not change much compared to straight down the centre when modelled. I did my own version
There's some mention / photo of a wedge shaped throat adaptor but no dimensions available. I made the throat equal to the cross section of the horn flare where it enters.
Am hoping to pick up some mdf soon to build a test horn and measure. I have a test driver on its way that seems to model as good as the EVM drivers so will post up measurements as soon as they happen.
Once scaled there were 2 immediate problems - the cab scaled to 1220 x 820 (not 810) and the wood thickness ended up being around 30mm (~1 1/4") !
I went with the 1220 x 810 outer dimensions and worked out centrelines for all the flare pieces, converting to 18mm (3/4")
I had to shift the position of the 2 pieces that form the throat by 3mm each to get them to touch each other.
I then put in a centreline to get the lengths worked out for the hornresp model. I looked up 'advanced centreline method' but so many long winded posts and a general consensus that it did not change much compared to straight down the centre when modelled. I did my own version
There's some mention / photo of a wedge shaped throat adaptor but no dimensions available. I made the throat equal to the cross section of the horn flare where it enters.
Am hoping to pick up some mdf soon to build a test horn and measure. I have a test driver on its way that seems to model as good as the EVM drivers so will post up measurements as soon as they happen.
Attachments
Rob,
Using the series 1 over forty years ago I found the EVM15L (lead) ribbed cone to distort much more than the 15B (bass) cone when driven below the FLH Fc (~65Hz) using ~100L back chambers.
There have been many series changes in the EVM line (series II, Pro-Line) and many drivers reconed differently over the decades.
Curious if yours have the ribs:
Art
Good question Art,
At the moment the drivers are EQ'd below 80Hz with a tiny back chamber on the Edgar style horns. (the chamber is a square just big enough to cover the driver, reactance annulled, same size as the Edgar midbass horn)
1 driver has the original ribbed cone with the EV logo on dustcap. The other has a non ribbed re-cone from a decent UK company.
The measurements between the 2 were very similar. I'm looking for the file now. Measurement from 2006, I'm getting old
Rob.
At the moment the drivers are EQ'd below 80Hz with a tiny back chamber on the Edgar style horns. (the chamber is a square just big enough to cover the driver, reactance annulled, same size as the Edgar midbass horn)
1 driver has the original ribbed cone with the EV logo on dustcap. The other has a non ribbed re-cone from a decent UK company.
The measurements between the 2 were very similar. I'm looking for the file now. Measurement from 2006, I'm getting old
Rob.
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Art,
If my model for the Thunderbolt is correct then 1 cab in 1.0pi will do 120dB with 12.5W. 4.0mm excursion maximum @37Hz.
The modelled roll off is ~3rd order so I could add a 1st order at ~35Hz to reduce excursion below Fc. As stated am planning 4th order BP below ~30Hz.
I'm planning on using 4 thunderbolt cabs in a 21 x 15 room for home theatre. Max spl for subs will be 121dB. (4 cabs in 1.0pi, 15 watts, under 2mm excursion per driver)
All these numbers are ignoring any room gain.
Compression ratio is 4.3:1 , is that too high ?
Thanks,
Rob.
If my model for the Thunderbolt is correct then 1 cab in 1.0pi will do 120dB with 12.5W. 4.0mm excursion maximum @37Hz.
The modelled roll off is ~3rd order so I could add a 1st order at ~35Hz to reduce excursion below Fc. As stated am planning 4th order BP below ~30Hz.
I'm planning on using 4 thunderbolt cabs in a 21 x 15 room for home theatre. Max spl for subs will be 121dB. (4 cabs in 1.0pi, 15 watts, under 2mm excursion per driver)
All these numbers are ignoring any room gain.
Compression ratio is 4.3:1 , is that too high ?
Thanks,
Rob.
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You wouldn't have any info on Vitavox Oracle type of Midbass would you?
Vitavox will still supply those cabs , finished or not, but I had no courage to ask about the cost..
https://www.vitavoxhifi.co.uk/products.php?page=constructor_series
Vitavox will still supply those cabs , finished or not, but I had no courage to ask about the cost..
https://www.vitavoxhifi.co.uk/products.php?page=constructor_series
4.3:1 is on the high side for the "B" cone, and higher for the "L" cone.
If you aren't pushing them past 2mm excursion shouldn't be a problem for either type cones.
I wrote to Vitavox . They build construction series unfinished cabs ,thunderbolt too. I asked if they would sell plans. VIitavox Mike responded that because they still sell them they won't supply plans. Seeing that they sell wooden replica of bir-radial horns for over $3000 each I didn't bother to ask about the price.
Weltersys , do you have any experience with EAW BH-500 scoop horn ? I never considered those kind of horns but I got old and far less ambitious....
Weltersys , do you have any experience with EAW BH-500 scoop horn ? I never considered those kind of horns but I got old and far less ambitious....
Last time I heard a pair of them was around 1985, used as the low end in a PA.
Sounded good down to ~55Hz, the BH-500 is -10dB at 50Hz, fairly typical of bass horns designed for PA/Disco use in the 1970's.
A fair amount of wasted volume in the cabinet, and though the curves in the "bent horn" (BH) make for a smoother response above ~200 Hz, not much use in the usual "sub" range.
I doubt if the EAW/RCF LF-384-R used in the BH-500 had much more excursion than the EVM 15L (or 15B), which has only 3.3mm.
Those lightweight cones are very efficient, but can't move a lot of air compared to more modern drivers- a pair of LAB12 in a ported cabinet of half the size of the BH-500 could put out a lot more LF, and do another octave lower.
JBL "scoops" like the 4520 or 4530 are rear loading horns with the driver directly radiating forward, and have a deep cancellation null ~150Hz due to that arrangement.
The response above the response hole is more or less that of the driver in a standard baffle, providing none of the mid-bass impact of the Edgar Thunderbolt or BH-500 designs.
The Thunderbolt or BH-500 are offset driver front loaded horns, as you can see in Rob's Hornresp simulations in post #3&4, the first cancellation is up around 700Hz.
The response above the response hole is more or less that of the driver in a standard baffle, providing none of the mid-bass impact of the Edgar Thunderbolt or BH-500 designs.
The Thunderbolt or BH-500 are offset driver front loaded horns, as you can see in Rob's Hornresp simulations in post #3&4, the first cancellation is up around 700Hz.
Correct . It was so long ago I forgot they were BLHs. What attracts me in Bh-500 ( besides the price) is that it is a real midbass horn and not a glorified pipe. I can hang the tweeter inside the mouth and cobble the mid-horn on the top and have it playing in no time. Unfortunately the owner said he put some " kicking " EV drivers in them.
Got it. Supposedly has some special EV driver instead of default RCF 15". I already like the boxes. Plenty of space to put tweeter inside the mouth bin. Round 290Hz wood tractrix horn on the top. Nice , solid plywood box which I can still manage to move around. Going to be plenty of fun
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If the EVX-150 drivers are functioning normally, you won't find anything much better for the BH-500.
I've used the EVX-150 as high as 800Hz in FLH cabinets, replaced all my 15Bs with them for use up to 200Hz in PA usage in the late 1980s when they were introduced.
With the FDD (Flux Demodulation Device) shorting ring, and almost double the linear excursion of the EVM15L or B, the EVX-150 are a lot cleaner sounding in the sub-500 Hz range, especially for loud 50Hz reproduction.
I've used the EVX-150 as high as 800Hz in FLH cabinets, replaced all my 15Bs with them for use up to 200Hz in PA usage in the late 1980s when they were introduced.
With the FDD (Flux Demodulation Device) shorting ring, and almost double the linear excursion of the EVM15L or B, the EVX-150 are a lot cleaner sounding in the sub-500 Hz range, especially for loud 50Hz reproduction.
I have not much experience with high wattage power handling Pro woofers and rely on online "opinions " And opinions are that those drivers sound dead when used in Home audio installations and 8- 20 Watts of SET tube amplification which is what I'm planning to use.I will cobble something in test garage setup withing next week or so. Anyway , the weather is great , warm and sunny and I took two trips with my beaten up hatchback to haul in the horns..It's been too long and I'm getting sick of small stand mounted audiophile monitors in fart boxes. They do have a nice piano finish and high tech look..