Can someone comment on my hornresp simulations on the MCM8?

blamus · 22nd November 2010, 04:08 AM

Just started to learn how to use hornresp. can the TH experts give me some comments just for educational purposes? the aim is to get as high SPL as possible in as small an enclosure between 35-80Hz, in a vehicle powered by a 70W amp at 2 ohms.

best regards

MaVo · 22nd November 2010, 08:16 AM

Number 1 looks fine to me. Its interesting how you got that design to work by using such a long L12. I usually try to make L12 as short as possible, but here it seems to be better your way.
Number 2 has this deep notch directly above the passband. If the real box is just slightly off (which is very likely to happen - happened to me all the time), it could jump right into the passband.
Try to make your designs a little "safe" or "stable" concerning parameter variation, because what you build will never be a 100% representation of what you design.

All that said, i would go with no.1.

blamus · 22nd November 2010, 10:10 PM

Thanks Mavo for the comments!

Thats a very valid point about the huge notch may get into the passband when built, I never even thought about it that way.

I made some adjustments/improvements - smaller and louder:

Now all my simulations are done in 2pi and 2.83v, so I can compare to other box programs such as winisd

3. Flat from 40-100Hz at 99db, at 75L - This is a variation from TH1 above, smaller, higher SPL, flatter.

4. 30-80Hz, 93-99db, rising response at about 6db/oct. 46L. This I think I like. I believe the response shape here is perfect for cabin gain. Larger than TH2 above, the notch is still there but at a higher freq, way above the low pass would be used.

displacement seems fine at 12V (70W@2ohms) if I high pass at 25Hz.

This time I have included both screenshots and the honresp export, so people can just look at it or import it if they want to play with it (please!)

What do people think? Are these designs worth pursuing? As in, can it be improved much more?

littlemike · 22nd November 2010, 10:31 PM

Compression (area of horn at throat entry vs Sd) looks a little high. I tend to aim for values lower than 4 with these drivers.

Brian Steele · 22nd November 2010, 10:50 PM

Quote:

Originally Posted by blamus

What do people think? Are these designs worth pursuing? As in, can it be improved much more?

Caution: I don't think HornResp includes losses in its modelling. What looks flat in the same might not end up being flat when you measure it. Rolloff might end up being higher and faster than predicted, for example. On the plus side, the response is likely to be smoother than predicted.

blamus · 23rd November 2010, 05:19 AM

Quote:

Originally Posted by littlemike

Compression (area of horn at throat entry vs Sd) looks a little high. I tend to aim for values lower than 4 with these drivers.

You mean the ratio hornresp shows when I put the mouse over S2? I have done a bit research there and apparently jbell has tried using a compression ratio up to 8:1 and its fine for these particular drivers. But I maybe wrong.

Quote:

Caution: I don't think HornResp includes losses in its modelling. What looks flat in the same might not end up being flat when you measure it. Rolloff might end up being higher and faster than predicted, for example. On the plus side, the response is likely to be smoother than predicted.

So do you think sim 3 would work better even with cabin gain? Which one do you think would work best in the average car? Or do you think none of them are any good? Am I doing the right thing/heading in the right direction? I really have no idea!

mwmkravchenko · 24th November 2010, 03:20 AM

Quote:

You mean the ratio hornresp shows when I put the mouse over S2? I have done a bit research there and apparently jbell has tried using a compression ratio up to 8:1 and its fine for these particular drivers. But I maybe wrong.

4 to 1 is usually safe. 8 to 1 is asking for some blown drivers if they are not tough enough. Remember that the ratio is describing the area of the cone to the area of the throat. That means that what ever pressure is being created by cone movement is being amplified by roughly eight times.

Mark

littlemike · 29th November 2010, 03:35 AM

Jim got away with high compression by using a compression chamber, something you don't have. Additionally, his is a front-loaded horn, not a tapped horn.

I've not taken these drivers much above 4:1 in tapped horns. I've not killed a driver yet, but I really have not tried.

jbell · 29th November 2010, 12:24 PM

yea, 8:1 with a compression chamber works great -- I've yet to rip a cone in that configuration -- and I've tried. 8:1 FLH with chamber is the most efficient config I've found. I've yet to find a TH config for the mcm that will beat the FLH's I've done.

I'm not sure why you are using 2.83 volts and 2pi with a pair of 4ohm drivers in parallel?

If you want a 1 watt reading @ 2 ohm, you need to be using 1.41volts.

MaVo · 29th November 2010, 07:32 PM

Have you ever tried the 8:1 without a compression chamber? And what size do you use?

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
how accurate are the box simulations?	scampo77	Car Audio	20	3rd November 2009 04:06 AM
Seas L15 simulations	Khron	Multi-Way	3	11th April 2006 04:38 AM
Assistance with SPICE Simulations	JMB	Multi-Way	2	8th February 2006 09:28 PM
Xamp-simulations problem_s	grataku	Pass Labs	25	31st July 2003 05:10 PM
Protel simulations	Kees	Solid State	2	12th November 2002 03:47 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

22nd November 2010, 08:16 AM	#2
MaVo diyAudio Member Join Date: Jan 2006 Location: Herne	Number 1 looks fine to me. Its interesting how you got that design to work by using such a long L12. I usually try to make L12 as short as possible, but here it seems to be better your way. Number 2 has this deep notch directly above the passband. If the real box is just slightly off (which is very likely to happen - happened to me all the time), it could jump right into the passband. Try to make your designs a little "safe" or "stable" concerning parameter variation, because what you build will never be a 100% representation of what you design. All that said, i would go with no.1.

22nd November 2010, 10:31 PM	#4
littlemike diyAudio Member Join Date: Jul 2008 Location: Pacific Northwest	Compression (area of horn at throat entry vs Sd) looks a little high. I tend to aim for values lower than 4 with these drivers.

29th November 2010, 03:35 AM	#8
littlemike diyAudio Member Join Date: Jul 2008 Location: Pacific Northwest	Jim got away with high compression by using a compression chamber, something you don't have. Additionally, his is a front-loaded horn, not a tapped horn. I've not taken these drivers much above 4:1 in tapped horns. I've not killed a driver yet, but I really have not tried.

29th November 2010, 12:24 PM	#9
jbell diyAudio Member Join Date: Apr 2003 Location: .	yea, 8:1 with a compression chamber works great -- I've yet to rip a cone in that configuration -- and I've tried. 8:1 FLH with chamber is the most efficient config I've found. I've yet to find a TH config for the mcm that will beat the FLH's I've done. I'm not sure why you are using 2.83 volts and 2pi with a pair of 4ohm drivers in parallel? If you want a 1 watt reading @ 2 ohm, you need to be using 1.41volts.

29th November 2010, 07:32 PM	#10
MaVo diyAudio Member Join Date: Jan 2006 Location: Herne	Have you ever tried the 8:1 without a compression chamber? And what size do you use?