I'm totally new to THs. i have done a lot of reading here and on other forums and finally decided to make one so i could hear what they sound like. i took Patrick Bateman's double driver idea and crossed it with FlipC's mini clone design. i did not do any modeling and sort of made it up as i went along. here is what i came up with. i'm using the MCM 55-2421.
here are the cut measurements of my wood:
20.75" x 9.5"
16.5" x 9.5"
14" x 9.5"
12.5" x 9.5" - 15 degree angle on one end
10" x 9.5"
24" x 9.5"
24" x 9.5"
23" x 9.5"
24" x 24"
24" x 24"
it sounds pretty good but could it sound better? or am i way off here? i think the throat is 12.5"
i'm using a QSC PLX 2404 to drive it. how hard can i drive these? i'm using the sub out of a Behringer FBQ1502 set at 75hz. is this right or can i set it at 100hz?
my plan is to make 4 of these for use in a PA system.
Thanks,
bob
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
here are the cut measurements of my wood:
20.75" x 9.5"
16.5" x 9.5"
14" x 9.5"
12.5" x 9.5" - 15 degree angle on one end
10" x 9.5"
24" x 9.5"
24" x 9.5"
23" x 9.5"
24" x 24"
24" x 24"
it sounds pretty good but could it sound better? or am i way off here? i think the throat is 12.5"
i'm using a QSC PLX 2404 to drive it. how hard can i drive these? i'm using the sub out of a Behringer FBQ1502 set at 75hz. is this right or can i set it at 100hz?
my plan is to make 4 of these for use in a PA system.
Thanks,
bob
is your response pretty flat? or do you have notes that stick out really loud?
From my guesstimates on your TH from pictures, if you would have started at 1" of space at the start of the horn, instead of 0", and then follow the flare around, you should have a nice even response. Horn resp says you should get 120db at 40v, drivers in series. 40v is as far as I would push them.
From my guesstimates on your TH from pictures, if you would have started at 1" of space at the start of the horn, instead of 0", and then follow the flare around, you should have a nice even response. Horn resp says you should get 120db at 40v, drivers in series. 40v is as far as I would push them.
Im curious about phase response.
Since the drivers are offset and 1 isn't inverted.
Also be a bit more descriptive in "how it sounds".
Suggest simple tone test. Hook up a laptop and use it to generate specific frequencies. Start at 20 Hz and go up by 5 Hz each time. Make notes about perceived loudness. If you have ability to measure SPL well then this is mute. Do that.
Either way. It will allow you to know
if there any real problems with the design. Also will let you know how to EQ out those problems if they exist.
And what wood is that?
Good build.
Since the drivers are offset and 1 isn't inverted.
Also be a bit more descriptive in "how it sounds".
Suggest simple tone test. Hook up a laptop and use it to generate specific frequencies. Start at 20 Hz and go up by 5 Hz each time. Make notes about perceived loudness. If you have ability to measure SPL well then this is mute. Do that.
Either way. It will allow you to know
if there any real problems with the design. Also will let you know how to EQ out those problems if they exist.
And what wood is that?
Good build.
Thank you for all the replies and suggestions so far. i will answer some of the questions:
yes drivers are wired in series.
i'm using 1/2" mdf for most of the box. the brown wood on the inside is 3/4" mdf. this is just a test box i made with scraps i had. the real box will be made with baltic birch.
as for the flatness and sound. i'm totally new to this so i'm not sure what i'm listening for. i have ordered an spl meter and downloaded tone generating software. i will run the test as suggested and try stuffing foam in the end and running the test again. is there a certain distance the spl meter needs to be and volume setting?
thanks again,
bob
yes drivers are wired in series.
i'm using 1/2" mdf for most of the box. the brown wood on the inside is 3/4" mdf. this is just a test box i made with scraps i had. the real box will be made with baltic birch.
as for the flatness and sound. i'm totally new to this so i'm not sure what i'm listening for. i have ordered an spl meter and downloaded tone generating software. i will run the test as suggested and try stuffing foam in the end and running the test again. is there a certain distance the spl meter needs to be and volume setting?
thanks again,
bob
The "usual" way for testing subs, especially for PA use, is outside with no boundaries for at least 50 feet (1/2 space). Microphone is place at ground level for what's called near coincidence at a distance of 10 meters and power is run at 100W (28.3Vrms@8ohms). The chart you get scales perfectly to 1W/1M. Big office building parking lots are good for this on weekends when no one is there. You can always go smaller by doing it in your driveway, closer, and less power for checking flatness.
here are the results of my spl test. it has been raining here pretty hard so i could not go out side to do measurements. this was done in my garage at 1 meter 2.83 volts.
30hz 28
35hz 30
40hz 56
45hz 68
50hz 76
55hz 80
60hz 76
65hz 81
70hz 81
75hz 83
80hz 84
85hz 86
90hz 86
looks like it does not do so good in the lower end.
bob
30hz 28
35hz 30
40hz 56
45hz 68
50hz 76
55hz 80
60hz 76
65hz 81
70hz 81
75hz 83
80hz 84
85hz 86
90hz 86
looks like it does not do so good in the lower end.
bob
It's +/- 5db from 50 to 90hz... That's about what I'd expect from the MCM. It has a very low QTS. That's one of the reasons I like it so much, it's very horn friendly. Woofers with a high QTS end up needing huge enclosures if you horn load them.
If you want to get some more bass out of it, go to Radio Shack and buy about six 10ohm resistors. They're $1.99 each in a pack of two. Wire all six in parallel. Then re-measure the response. It should play lower. If it's too peaky, remove a resistor. Re-measure again. If it's still too peaky, repeat.
If you're in SoCal, SpeakerCity in Burbank stocks some monster resistor values. I think Apex Jr sells them too.
Uh oh, are you talking about "the smallest tapped horn" thread?
I wound up building that, but with three woofers, and a different layout. Here's the info:
Small Tapped Horn For a Car - DIY Mobile Audio
I still want someone to chime in about
the possible cancellation from the phase differences due to the distance differences.
In all of the Danley dual setups
the 2 drivers are at an angle to each other and then the quad and 8x setups are push pull.
Anyone?
On a side note.
There are 2 phenomenon's I have scene is TH's. A contradiction if you will.
One is that you can get decently high SPL from a small enclosure with less power. Or you can get allot more power handling before Xmax.
I have 2 designs that can take well over 300v (4ohm) and still not be at Xmax. To bad the driver cant handle the 23K watts. (anyone got a 21" driver that can?)
So retest your subs
outside and turn them up unto you here them clap a bit. Turn them down a bit from there. Retest SPL. If you can measure voltage (how are you measuring?) it will give you a better understanding of how well the layout/design does.
Cause when are you ever going to listen to them with just a single watt?
the possible cancellation from the phase differences due to the distance differences.
In all of the Danley dual setups
the 2 drivers are at an angle to each other and then the quad and 8x setups are push pull.
Anyone?
On a side note.
There are 2 phenomenon's I have scene is TH's. A contradiction if you will.
One is that you can get decently high SPL from a small enclosure with less power. Or you can get allot more power handling before Xmax.
I have 2 designs that can take well over 300v (4ohm) and still not be at Xmax. To bad the driver cant handle the 23K watts. (anyone got a 21" driver that can?)
So retest your subs
outside and turn them up unto you here them clap a bit. Turn them down a bit from there. Retest SPL. If you can measure voltage (how are you measuring?) it will give you a better understanding of how well the layout/design does.
Cause when are you ever going to listen to them with just a single watt?
Are you saying that just because you design a horn where the speaker can handle X number of times it's rated power, you can't feed the speaker the wattage the enclosure can handle? Example: the MCM 55-2421 is rated at 120w RMS. If I designed a horn where the MCM can stay under 8mm Xmax @ 1,200w RMS, I can't actually give the 55-2421 that amount of power?
That's right. There are 2 types of output limits in a driver- thermal and excursion. Most of that 1200W is converted to heat in the voice coil, so, imagine the heating element of a hair dryer as a loudspeaker voice coil.
Doesn't result in such a good ending, does it?
NO!
Just that a TH acts like band pass sometimes.
Though with a TH design as such you can probably run the driver over the rated max input level. Having the magnet and coil assembly facing out at the mouth means you have great heat dissipation. I have ran mine at full throttle for over 5 hours straight and they weren't hot. Warm yes but not like a driver in a FLH.
I was just stating there seems to be 2 avenues you can go
with a TH design.
Just that a TH acts like band pass sometimes.
Though with a TH design as such you can probably run the driver over the rated max input level. Having the magnet and coil assembly facing out at the mouth means you have great heat dissipation. I have ran mine at full throttle for over 5 hours straight and they weren't hot. Warm yes but not like a driver in a FLH.
I was just stating there seems to be 2 avenues you can go
with a TH design.
No, you can't. The magic smoke comes out. I learned this the hard way, and I have the pictures of the aftermath somewhere.
The voice coil can not dissipate the heat generated by pushing high currents and voltages through it. The heat melts the coil former, which distorts and causes the cone to stop moving. Once the motion of the cone stops pumping air through the gap, things really warm up and the glue and varnish smokes. If you cut power at this point, you'll still have continuity through the coil, but it is more of a copper slinky. I stopped here, as it was pretty obvious that something broke (the big noise stopped). Had I kept going, I could have killed my amp or lit something on fire.
Sorry but I am laughing.
Cause I like to take burnt drivers and feed them direct current and watch what happens.
I have never caught a speaker on fire inside
a cabinet. Though I have burnt out drivers. Only due to either a DC surge. (damn generator) or the access panel coming loose. (happened more than once)
Hmm,
My mind starts thinking about the years I spent overclocking CPU's. Anyone know if there has ever been a super cooled speaker? IE other than air?
You get rid of the heat
you can push more power. Normally though you are talking about a sealed enclosure. So it is just getting hotter and hotter. hence the cooling plates on Lab Subs and some other FLHs. A reflex box has some cooling but the TH has a big advantage here. To a point it comes down the cone and its parts not being able to withstand the pressure.
Which I have also done in testing band passes.
Cause I like to take burnt drivers and feed them direct current and watch what happens.
I have never caught a speaker on fire inside
a cabinet. Though I have burnt out drivers. Only due to either a DC surge. (damn generator) or the access panel coming loose. (happened more than once)
Hmm,
My mind starts thinking about the years I spent overclocking CPU's. Anyone know if there has ever been a super cooled speaker? IE other than air?
You get rid of the heat
you can push more power. Normally though you are talking about a sealed enclosure. So it is just getting hotter and hotter. hence the cooling plates on Lab Subs and some other FLHs. A reflex box has some cooling but the TH has a big advantage here. To a point it comes down the cone and its parts not being able to withstand the pressure.
Which I have also done in testing band passes.
I made a second box. I added an extra fold in the design. The throat area is a constant 1" up to the next fold. I messed up and cut the driver board to short. you can see in the first photo how i patched it up to make it work.
Here is the cut list
9.5" x 19.5" - 5 degree angle on one end
9.5" x 3.5"
9.5" x 19.75"
9.5" x 16"
9.5" x 13.25"
9.5" x 10"
9.5" x 13.75" - 5 degree angle on one end
9.5" x 24"
9.5" x 24"
9.5" x 23"
24" x 24"
24" x 24"
I live in oregon and it has been raining here, so i can't go out side to do measurements. These were done inside at 2.83v / 1 meter:
30hz 28
35hz 44
40hz 63
45hz 71
50hz 77
55hz 79
60hz 72
65hz 78
70hz 82
75hz 80
80hz 81
85hz 82
90hz 82
To me the second box sounds better. By the numbers there is a little more low end and the upper end has evened out. I have not tried corner loading but guess that the numbers will be higher.
I'm an armature here and really have no idea what i'm doing. Is it over kill to have 2 drivers in this box? Is this design looking good or bad? I'm really looking for something that is small and easy to lug around. This design is small but if it is not going to preform well then i need to look at another design.
bob
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Here is the cut list
9.5" x 19.5" - 5 degree angle on one end
9.5" x 3.5"
9.5" x 19.75"
9.5" x 16"
9.5" x 13.25"
9.5" x 10"
9.5" x 13.75" - 5 degree angle on one end
9.5" x 24"
9.5" x 24"
9.5" x 23"
24" x 24"
24" x 24"
I live in oregon and it has been raining here, so i can't go out side to do measurements. These were done inside at 2.83v / 1 meter:
30hz 28
35hz 44
40hz 63
45hz 71
50hz 77
55hz 79
60hz 72
65hz 78
70hz 82
75hz 80
80hz 81
85hz 82
90hz 82
To me the second box sounds better. By the numbers there is a little more low end and the upper end has evened out. I have not tried corner loading but guess that the numbers will be higher.
I'm an armature here and really have no idea what i'm doing. Is it over kill to have 2 drivers in this box? Is this design looking good or bad? I'm really looking for something that is small and easy to lug around. This design is small but if it is not going to preform well then i need to look at another design.
bob
Just 'cause the magnet structure isn't hot, means nothing about the coil temp itself and how well (or not well) it can dissipate that quickly to the surrounding steel.
I was testing some tweeters about a year ago at my job and you wouldn't believe how fast coil temp can spike on peaks. Same concept applies larger coils of woofers, but there is more mass so things don't go poof as quick.
I was testing some tweeters about a year ago at my job and you wouldn't believe how fast coil temp can spike on peaks. Same concept applies larger coils of woofers, but there is more mass so things don't go poof as quick.
What if the magnet & coil assembly is mounted in the throat of a FLH? Shouldn't the same heat dissipation apply?
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