Oh so the minimum occurs at the Fb. I had it wrong in my head. I was thinking the first peak was the Fb and that maybe the second peak had something to do with the Fs being shifted higher due to being in the box and not in free air..
You mean there is actually something you don't have a clue about regarding speakers. Say it isn't so.
Every driver has an impedance peak at its natural resonance, Fs, in free space.
When you put it in a sealed box the peak moves to the resonance of the box, Fb, and its shape will change depending on the size of the box - narrower in a smaller box and wider in a larger box.
When you put it in a vented box you get 2 impedance peaks this time with the minimum between them at the box resonance, Fb. Or conceptualized another way, you again get 1 large impedance peak that is split in 2 (not necessarily in half) by the null at Fb. So in the same way that the cone has very little travel at Fb, so too does the vented box impedance peak have a null in the same place. Interestingly, the shape of this (larger) impedance peak operates in the opposite manner than the sealed one - in a small box it's wider (so the 2 smaller peaks are wider apart) and in a large box it's more narrow (2 peaks closer together) . (Don't ask me to explain why, I haven't got a clue)
Now as to the effects of leakage on impedance, you're going to have to ask Dissi that. I noticed the difference in your 2nd impedance peak too but I didn't know what it meant. Dissi?
As far as making your cab air tight, many people use thin weather strippping or some other thin closed cell foam as a gasket for a removable baffle. But that removable panel needs to be air tight as well.
As a learning tool btw, I have found Unibox to be an invaluable tool. I think it does a few more things than WinSD does but I also find its user interface much easier to use and to learn from. Play around with that for a few hours and all kinds of cause and effect relationships start to become very apparent. It needs Excel though.
UniBox - Unified Box Model for Loudspeaker Design
Oh - enjoyed the humor. Hope your head is feeling fine today.
Tony,
Reason I was wondering what this 1.3'³ box dimensions were is the length, especially true in tall thin enclosures where they start to exhibit Transmission Line (in your case MLTL) tendencies and corresponding misalignment's. A loose front baffle and lack of dampening unfiltered raw can be quite disconcerting depending on driver used, but is expected for the untrained ear. Again not a problem, we've all done it
High FIVE Phoenix
Tony,
Reason I was wondering what this 1.3'³ box dimensions were is the length, especially true in tall thin enclosures where they start to exhibit Transmission Line (in your case MLTL) tendencies and corresponding misalignment's. A loose front baffle and lack of dampening unfiltered raw can be quite disconcerting depending on driver used, but is expected for the untrained ear. Again not a problem, we've all done it
High FIVE Phoenix
Just sent you a PM.
Tony
Well I compared latest published specs against Zaph's seeing that there is so much difference between the three versions I currently have.
Zaph|Audio
Still a bit of discrepancy, which to believe.
Zaph|Audio
Still a bit of discrepancy, which to believe.
Tony's been goofing off. Out playing in the ##&&$!# snow. The cabinets are just about done. I stained the baffles. As Greebster mentioned they are set up (with the wrong crossovers) but sounding pretty good. I need to pick up a sheet of black laminate for the sides but the back of my pickup truck is filled with snow and I ain't shoveling it out. Maybe I should just use some iron-on edge banding and stain the sides as well.
Whats a good next project? Maybe a subwoofer?
So I'm still trying to make some sense of the port. Now some of you are are going to roll your eyes and say "where does he come up with these lame brain methods" but here's what I did:
I connected a signal generator to the speaker. I set it to 40 Hz and then put the port (4" long) in place. I could hear a definite increase in volume with the port in place. Like wise pulling out the port I could hear a drop. Same thing at 50Hz. At 60 Hz there was no difference. At 70, 80, 90 and 100 I could hear a decrease in output with the port in place. Above 100 it made no difference. I don't now if this is normal but to me with music playing it sounds better without the port - just the 3/4" thick port opening.
Tony
I connected a signal generator to the speaker. I set it to 40 Hz and then put the port (4" long) in place. I could hear a definite increase in volume with the port in place. Like wise pulling out the port I could hear a drop. Same thing at 50Hz. At 60 Hz there was no difference. At 70, 80, 90 and 100 I could hear a decrease in output with the port in place. Above 100 it made no difference. I don't now if this is normal but to me with music playing it sounds better without the port - just the 3/4" thick port opening.
Tony
Tony...you may be over thinking the "power" of a pair of 6.5".
Even if you had a pair of boxes made of the best plywood, with lots of bracing, you still might be wondering what happened to the bass.
[e.g. we installed a 8 - 6.5" woofer in the HT today - earth quake sub]
[post 480 http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-48.html]
Point being, 2 is only going to do so much.
I think you hit the nail on the head with a 10" or 12 sub-woofer and plate amp.
Even if you had a pair of boxes made of the best plywood, with lots of bracing, you still might be wondering what happened to the bass.
[e.g. we installed a 8 - 6.5" woofer in the HT today - earth quake sub]
[post 480 http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-48.html]
Point being, 2 is only going to do so much.
I think you hit the nail on the head with a 10" or 12 sub-woofer and plate amp.
Your link does not work.
I'm just trying to learn things and as I mentioned trying to get the port right. Heres what I think of these dayton drivers right now. At low volume they could use more bass (keep in mind I'm still waiting for the xo parts). At mid volume they seem to have plenty of bass and are pleasing. At high volume they also have plenty of bass, sound ok but the daytons are working very hard at that point and lack real punch.
I'm going to fess up here and admit what I know about "good" or high end sound. The best speakers I ever had were almost free. I traded someone a Denon dual cassette deck for them (the Denon developed several problems in less than a year). They were some japanese name like mitsubishi or something and were a generic department store junk 12" 3 way. I liked them. Next best was some realistics that were buy one get one free. I don't remember if they were 8" or 10" but it had a passive radiator, which over the years RS offered several different ones but these were the only ones that were tall and skinny.
http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-48.html
post 480 - it's shaking the room and may be the worlds best $64 subwoofer.
Did you ever hook up the amp/receiver with the generator/resistor? It only takes a few minutes and you can see and hear whats going on.
http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-48.html
post 480 - it's shaking the room and may be the worlds best $64 subwoofer.
Did you ever hook up the amp/receiver with the generator/resistor? It only takes a few minutes and you can see and hear whats going on.
http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-48.html
Got the crossover parts in and built one for the right side. I think jReaves nailed this right on with his xo design. It sounds great. How do I know that? Well it sounds much better than the left side (which still has the wrong xo) and also the overall balance of it is hard for me to distinguish from comparing it to an Overnight Sensation MTM. Therefore I guess it sounds the way a speaker is supposed to. I'm still learning.
However, for my ears, both the DA175 system and the OS MTM could use a hint more brightness or presence if those are correct terms. The vocals sound a little subdued and distant. Thus far I changed resistor R2 from 1.5 Ohms to 2.0 ohms. Seems to have made the difference. I'll get the second xo built so I can hear both speakers.
Tony
However, for my ears, both the DA175 system and the OS MTM could use a hint more brightness or presence if those are correct terms. The vocals sound a little subdued and distant. Thus far I changed resistor R2 from 1.5 Ohms to 2.0 ohms. Seems to have made the difference. I'll get the second xo built so I can hear both speakers.
Tony
Good to hear! You will want to wait til the other crossover is built before swapping resistors. Everything changes when listening to stereo, especially once balanced against each other.
Oh no I'm afraid I gave you too much bass!!!!
Very happy that it's working out for you. And to let you know, the final step in any design is to fine tune it by ear. And R2 = 2ohm is exactly the adjustment you should have made. I think you can also change R1 to 5.5ohm for a more subtle increase in the high frequencies but if my sims are right (which it's possible they aren't - your driver responses may be a little different than what I used), I think larger changes than that will be too much.
I agree with Greebster, wait for both speakers to be done and hopefully you also have some form of insulation in them now as well. Judge the speakers at the SPL level that you normally like to listen at - you already discovered that the balance changes with more or less volume (the perception of bass and treble diminish as you turn down the volume - thus the use of the old loudness button) and give yourselves a little time and different material to get use to any xo iteration. If you are perhaps finding that the bass is still smothering some of the vocals, try pulling the speakers out from the back and/or side walls. That should drop the bass level a little.
Cheers
I'm afraid I gave you too much bass!!!! Very happy that it's working out for you. And to let you know, the final step in any design is to fine tune it by ear. And R2 = 2ohm is exactly the adjustment you should have made. I think you can also change R1 to 5.5ohm for a more subtle increase in the high frequencies but if my sims are right (which it's possible they aren't - your driver responses may be a little different than what I used), I think larger changes than that will be too much.
I agree with Greebster, wait for both speakers to be done and hopefully you also have some form of insulation in them now as well. Judge the speakers at the SPL level that you normally like to listen at - you already discovered that the balance changes with more or less volume (the perception of bass and treble diminish as you turn down the volume - thus the use of the old loudness button) and give yourselves a little time and different material to get use to any xo iteration. If you are perhaps finding that the bass is still smothering some of the vocals, try pulling the speakers out from the back and/or side walls. That should drop the bass level a little.
Cheers
Oh no
Very happy that it's working out for you. And to let you know, the final step in any design is to fine tune it by ear. And R2 = 2ohm is exactly the adjustment you should have made. I think you can also change R1 to 5.5ohm for a more subtle increase in the high frequencies but if my sims are right (which it's possible they aren't - your driver responses may be a little different than what I used), I think larger changes than that will be too much.
I agree with Greebster, wait for both speakers to be done and hopefully you also have some form of insulation in them now as well. Judge the speakers at the SPL level that you normally like to listen at - you already discovered that the balance changes with more or less volume (the perception of bass and treble diminish as you turn down the volume - thus the use of the old loudness button) and give yourselves a little time and different material to get use to any xo iteration. If you are perhaps finding that the bass is still smothering some of the vocals, try pulling the speakers out from the back and/or side walls. That should drop the bass level a little.
Cheers
jReaves. These things are sounding quite good to me - both at low volume and high volume. I'd say the best I've ever had but with some minor tweaking will be even better. The bass is great. I've got the bass set at "0" now. In the past I always had the bass up around "+5" or even more. I do wish though that receivers still had loudness buttons to enhance the bass at low volume. Why did they stop including them?
I'm not qualified to review or compare speakers but I'll say what I observe right now comparing it to the OS MTM. The OS MTM is an impressive little thing. At low volumes the DA175 system has more bass and sounds richer. At med volumes its a toss up but the OS MTM plays louder (better sensitivity ?) and has what seems to be "tighter" bass but the DA175 systems seems to go a little deeper. Increasing the volume the DA175 system steals the show with punch you can feel and maintaining its integrity while the OS starts to get a little mushy. I don't know what I'm talking about. Probably comparing apples to oranges but its all I got
I do have both of these set up now with the proper crossover but one has the 1.5 Ohm R2 and the other has the 2 Ohm. Getting confusing now hearing both of them as to which is actually better.
You did a great job. Thanks
Tony
More and more I'm starting to think "cheers" is appropriate.......
I know it is for me. Californian red tonight.
Cheers
After putting up with me for the last couple of weeks you need something stronger. PM me your address and I'll send you a bottle of Chivas Regal.
Hey Tony, that's really generous of you but totally unnecessary - I am happy to have helped you out and that's its own reward. Besides, I'm in Canada - shipping booze over the border here is going to cost you an arm and a leg (booze tax in this country is sinful). I'd rather you spend the money on better drivers or your next project or something.
So, with both speakers done and hooked up do the vocal levels or the overall balance sound better now? I was thinking that since the vocals are pretty much always mixed in stereo whereas other instruments might be mixed either left or right, that 2 speakers together would solve the problem.
The OS MTM's are more sensitive so they should play louder with the same input and indeed they shouldn't play as low as the Dayton since they're only 4" drivers, but it's interesting that the 1 Dayton can still play louder for you than the 2 HiVi's - I wouldn't have guessed that without looking at the simulations with them.
A couple of other tweeks that might help - put the speakers on spikes and, if you are happy with the configuration as is, fill the bottom space with some sand. Both of those are supposed to improve the quality of the bass. Give them a try and see what you think.
Oh, and tell Phoenix to take some pictures.
So, with both speakers done and hooked up do the vocal levels or the overall balance sound better now? I was thinking that since the vocals are pretty much always mixed in stereo whereas other instruments might be mixed either left or right, that 2 speakers together would solve the problem.
The OS MTM's are more sensitive so they should play louder with the same input and indeed they shouldn't play as low as the Dayton since they're only 4" drivers, but it's interesting that the 1 Dayton can still play louder for you than the 2 HiVi's - I wouldn't have guessed that without looking at the simulations with them.
A couple of other tweeks that might help - put the speakers on spikes and, if you are happy with the configuration as is, fill the bottom space with some sand. Both of those are supposed to improve the quality of the bass. Give them a try and see what you think.
Oh, and tell Phoenix to take some pictures.
So, with both speakers done and hooked up do the vocal levels or the overall balance sound better now? I was thinking that since the vocals are pretty much always mixed in stereo whereas other instruments might be mixed either left or right, that 2 speakers together would solve the problem.
The OS MTM's are more sensitive so they should play louder with the same input and indeed they shouldn't play as low as the Dayton since they're only 4" drivers, but it's interesting that the 1 Dayton can still play louder for you than the 2 HiVi's - I wouldn't have guessed that without looking at the simulations with them.
Oh, and tell Phoenix to take some pictures.
The OS MTM probably does play louder. I'm just noticing that at a reasonably loud level the DA175's shake the walls, trigger cat toys and sound stronger and fuller than the OS. But!!! I don't understand why. The DA175's are working hard at high volume. Lots and lots of cone movement and I'm sure Xmax is being exceeded. Before I put the right crossover in, I had the bass turned up halfway and when playing loud, there was even more cone movement and strange distortions to go along with it.
Yeah you are right. With both speakers the vocals are stronger if I'm in front of the speakers. But if I'm somewhere else in the house it seems I have trouble hearing the vocals unless its on FM radio and a commercial is on. This system is probably right and every other speaker I ever had was wrong. I've played about 10 CD's through them and more and more I'm realizing how wrong the others were and how pleasing these are. My ears are probably in training right now.
Do you think I should reduce the box volume a little to help with the cone movement?
I'll see if I can P*ss Phoenix off and get him to post here again.
Tony
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