any simpler audio delay method?

So I happened upon this post thanks to Google and it definitely caught my interest. Poor mid-bass has definitely been my second biggest bane in my car audio setup (the biggest bane and perhaps more of an arch-nemesis would be the fact that I have a pretty bad budget and generally have to focus on home audio before car audio.) I always thought it was my speakers though. Right now I just have some Infinity "Reference" two-ways in the rear (I was given a gift-card for Best-Buy quite some time ago and saw nothing of any interest except speakers and they were the closest to anything actually resembling a reference sound of everything I could actually find there.) In the front it's even worse. I have some cheap SONY four ways (seriously, what the heck is that? It seems to consist mostly of just throwing in an extra even smaller tweeter presumably for frequency ranges humans can't even hear and normal audio equipment struggles even to produce) in the front. Needless to say, neither of these is really ideal for producing a smooth and relatively even response curve. I finally managed to solve my biggest problem -- the noise canceling in the trunk space -- via some simple foam baffles on the rear speakers (the only thing I can really fit in there due to the way they have some rods in the way of building real enclosures) sealed up and with fiberglass added (it's too bad I read about that AFTER I mistakenly thought the carpeting type material they used on the rear to cover the speakers was muffling the sound and cut a small amount out. Luckily I've since gotten some speaker grill cloth that almost blends perfectly so it doesn't really look too bad.) At least now I can drive with the rear seats closed. I don't miss having to always keep them opened (which meant whenever someone rode in my car I'd have to remember to get out, pop the truck, and pull the tabs to open them again afterwards to get proper sound back) and I definitely won't miss the extra road noise added to the music... Anyway, nothing I've done has really helped the mid-bass at all. After reading all of this, it would perfectly explain the problem. There's one problem: my arch-nemesis, Mr. Empty Wallet. I can't really replace the head unit, add an amp, get better speakers, or anything like that right now. However, I did have a thought as to how this may still not an impossible situation. I EXCLUSIVELY (without exception) listen via an external MP3 player plugged into the line-input of the stock unit (I can't say how glad I was that this came stock, lol.) So my thought on this is that if there were some method that an audio delay could be added to audio via perhaps some passive component or something of the sort, why not just add it to the audio before it even reaches the head unit? Even an active component might work if we're not talking about anything expensive or too troublesome to power (I wouldn't even be upset if it were battery powered or something as long as it were efficient enough that I could leave it on -- I just know I will forget to turn it off -- and not have to replace batteries every other day. Of course, the catch is that my car is of course exposed to fairly extreme temperatures, which isn't really ideal for alkaline or nickel-metal hydride batteries...) Unfortunately my relatively limited knowledge of electronics (audio or otherwise to be honest) doesn't really include any knowledge of anything relatively simple to add audio delays. It definitely wouldn't be realistic for me to try to process all of my music in software and try to keep all of that on just that one player. I add/remove things often enough that this could really become troublesome. (Plus most of my music is in lossy formats and going back and getting a lossless just for this would make the whole process even more painful, but there's no way I could fit this much lossless audio on my player.) Of course, I double checked that my player has no ability to do this and unsurprisingly it does not. Any thoughts on anything that might be possible given the budget limitations?

Reverse the polarity of one of the mid-bass speakers.

Actually the above is a phase delay of about 3ms (at 150Hz) which is too long. But I left that reply as is for the benefit of regulars. (Or ?) But knowing speaker impedance (resistance and inductance), a capacitance value might be able to be calculated for a nominal frequency (150Hz?) for series (maybe speaker) insertion. But phase will change with frequency. More than that gets complicated. And I presume you have tried other or better speakers & tuning etc?

Yeah, I already knew that having a completely inverted phase wouldn't work so well. Especially since I'd have to basically pull the thing apart and move around capacitors and such. As for other speakers, I've made a few attempts, but the problem is, as mentioned, budget. The only way I could use better speakers is if I figured out some way to rig up the mid-drivers I removed from my home system. They're relatively small, but I'd still have to do some major cutting or something to get them in there (or worse, actually remove the four ways and just have mids in the front and the rest in the back -- which really doesn't work well at all IMO.) There are limits to just how far I'm willing to physically modify my car right now as it's still in warranty and such (and you know how manufacturers will jump on the slightest excuse to void a warranty...) Right now the only modification I've made that can't be pulled out all too easily is the cutouts in that material on the back. I don't really have any tuning options. Sorry, I forgot that I hadn't actually saved my signature yet, so it didn't show up on there (and of course it won't let me edit, so I couldn't append it once it occurred to me after seeing your post.) Basically, due to the budget limitations, I'm still using the stock head unit and no external amplifiers. Right now my only options are a very basic three band equalizer and a fade/balance control. I did try playing with the equalizer a bit on the MP3 player itself (it's the Cowon X5, so it has pretty good options built in and a pretty even output) but not coincidentally I didn't get much help from even it in this department. As that article says, equalizers just don't help. ATM I can't really try to do much more tuning-wise than that though. That's why I was aiming for the less elegant, but minimal modification solution. Sadly, I can't even do anything with the front speakers. There's just no room in there since the windows come down right behind the speakers (in fact, at one point I tried some that it actually would come too close to and actually physically push the speakers out. Thank goodness the metal of the door had just enough flex that the speaker could move out rather than the glass breaking or something.) It also occurred to me that there might even be some digital devices for phase shifting or audio time offsets -- though I'm not really sure if any such device would be designed to to to such a small amount since their normal applications require much larger values than this calls for...Driving a 2006 Saturn Ion (2)

Still stock everything, including head unit (no extra amp) with cheap SONY four ways in the front and less cheap Infinity two ways in the back.

There are digital devices though I'm not up on what exists (maybe others hereon do?) I'd assume they use DSP chips/circuit (Digital Signal Processing) but I haven't worked with them in over 20 years. (Oops!) I imagine these days DSP chips are much cheaper, but I doubt DSP accessories like delays are not cheap. Depending on complexity and resolution, DSPs can be programmed or mapped to shift certain frequencies only based on frequency and volume and desired profile. (Much like EFI systems with their 3D mappings etc.) PS - probably a bandpass filter is best suited to your needs. You can build your own using cheap Op Amp ICs (a $few each). As to design, I'd be doing the same as you - searching or checking datasheets and Application Notes.

Well, it strikes me that there might be something out there specifically designed to do phase shifting for tuning of this very sort of nature even (though they probably wouldn't be thinking of cars specifically.) Why would a bandpass filter help?Driving a 2006 Saturn Ion (2)

Still stock everything, including head unit (no extra amp) with cheap SONY four ways in the front and less cheap Infinity two ways in the back.

Yes, you have been struck. There are plenty out there. The cheapest DSP module I've seen was about $130, but the next was $300 and most were $700 to $2,100. Whether or not they'll do the job I don't know. And many were PC cards. Since you want to delay a segment of frequency (mid bass) you need a bandpass filter. If you wanted all bass, you could use a low-pass filter. You then need to phase shift that filtered sound (and remove from the remaining signal). A problem with analog filters can be undesired phase shifts - but that is what you want - it's a matter of design. I suggest you drop this thread - you have the answers unless someone else has a suggestion. (Preempting) You may be better off with a new thread asking how to improved your mid-bass. I have been told of some simple layouts etc (but me not being into audio "systems"...). And when asking, make it short and sweet. A reasonable indicative title/subject/heading. Start with what you want or hope to achieve - ie, a problem summary or question. Describe your set up and equipment. Add other details that may help. (Generally in that order.) Do not make people have to search for the details. Good luck.

I think I'll wait until I have a solution or am absolutely sure that there isn't one before dropping the thread thanks... As you already touched on, no one else has even said anything yet. As for the bandpass, I don't think the original thread (did you read it? Just the first post is fine as nothing really important was said after that at least as far as this thread is concerned) really meant that you had to delay only the mid-bass. Eg it should be ok to delay the whole sound. Thus no band-pass should be necessary. Also, I doubt the head units and etc referenced in that thread with a built-in ability to do this really did it via as extreme methods as what you're talking about. I find it hard to believe that there's not anything less complex out there for the task. As for improving the mid-bass, I already know the alternate options even without creating a thread (and besides which, doesn't the thread I linked to already answer that very question? Why start a new thread when the answer is already right there?) There are limits to what you can do though as explained in that thread. I think he put it best when he pointed out that you're already working with a huge noise floor to begin with, so just making it louder or etc alone isn't going to cut it. I've already stated that I can't really afford to do stuff like getting really good speakers or a better head unit (or ideally both) atm though. Trust me, if I could I wouldn't be in here asking about trying to solve the problem via a cheap method.Driving a 2006 Saturn Ion (2)

Still stock everything, including head unit (no extra amp) with cheap SONY four ways in the front and less cheap Infinity two ways in the back.

Good, understood. I have underestimated your knowledge and research. (That's probably quite common on forums and is usually appropriate. How nice to have this un-usual request!!) A fixed delay is the easiest (apart from a suitable filter with phase shifting) but is hard do do analogally - that's why they used to use mechanical springs in ye old days. (I was thinking of suggesting that...) But then came electronic delays... were they "bucket brigade" devices? And now digital.... (Delaying digital bits is easy, but not analog signals.) Assuming I already had good speakers in the doors, a hi-pass filter around 70Hz to satellite speakers and an amped sub in the back (as suggested by a brilliant the12volt colleague recently - dare I name the well known contributor to give due credit?), I might consider some extra band-passed speakers. But that's probably not a "non-hacking door" etc option. I wish I could comment on the linked article. At first I thought crap, but I did not go into detail. And the its replies suggest my "crap" opinion is itself crap. I certainly felt intuitively a bit uneasy with it. Whether that was the implementation, or the theory I don't know. Alas I am totally confused now about what I knew ages ago about our aural senses. [ Trivial: That's unused info - I retain the odd >145dB is instant ear damage; 85dB(A) for 8 hours; bass is non directional - but that's almost it. OTOH, eyes and colors have been a common revisit - like how 95% of eyes are misaligned and hence can see 3D on 2D prints - I even recall some CIE-based standards (.2 u-v separations; no saturated blue targets under 2 degrees; etc). ] And I though the link referred to phase shift/angle rather than phase delay, but as long as the difference is understood. Geez - I can't even recall the cross spectrum effect of phase delays and phase shifts (other than out of phase as with inverting one (directions) speaker polarity) - yet I was into surround sound from mere 2-speaker stereos & headphones! LOL. If I find anything - including circuits (probably only from App Notes for chips etc), I'll reply later - even if it awakes this "old and ancient" thread. After all, ATM this is "our PMs posted publically" so only we get bugged (ie - notified by email - unless others have subscribed). Otherwise 'tis above me... But at least I have a good sound "principle" for my soon to hit the road 4WD. And should that fall short, you have provided an option. Cheers.

Thanks. And if I find anything of any use I'll post it here for anyone else who might be interested. I still can't help but to think that the fact that I have external access to the sound before it even reaches the head unit is an advantage though. I can't help but to think that there might be some simple IC (perhaps similar to an opamp) or something that could do such a task without having to go all the way up to the complexity of programmable DSPs or etc. Even those head units that have this built in might be using a DSP, but I doubt they use anything really complex or expensive to achieve such tasks. I can definitely see something like this needed in tuning audio more ideally in some locations or something, so it's hard to imagine that no simple cheap thing was ever designed for such a task. It is too bad that there is no simple analog method to do this, but if I knew of anything that even had any possibilities I wouldn't have asked. (And yeah, coiled springs definitely aren't going to cut it even if they were simple to implement.)

oldspark wrote: Good, understood. I have underestimated your knowledge and research.

I certainly hope so. I'm not going to deny that I'm still learning when it comes to audio electronics in general and of course technology (but then who isn't when it comes to technology?) I will say that I don't like to ask questions of such a nature if it's anything I can do myself with just a bit of research unless I just fundamentally do not understand something (like when I was first learning about the use of capacitors. You can find the equations as well as various convenient calculators and such, but, if you just don't understand how they work, it's still pretty confusing. It's also much harder to find those things if you don't actually know what you're looking for. If you put it capacitor on Wikipedia, it will specifically mention that they can be used for filtering, but finding this is not easy short of reading the entire article. Put in high-pass filter in Wikipedia and there is a simple equation just waiting for you...) [quote]Assuming I already had good speakers in the doors, a hi-pass filter around 70Hz to satellite speakers and an amped sub in the back (as suggested by a brilliant the12volt colleague recently - dare I name the well known contributor to give due credit?), I might consider some extra band-passed speakers. But that's probably not a "non-hacking door" etc option.[/quote] Well, let's also not forget that this might not even help to resolve the initial problem itself. Eg the noise floor is still there, so this is just making things generally louder. Another problem I have just atm however is the only speakers I have on hand which would be really good at mids would be the 3" drivers I pulled out of my home system. They aren't perfect at mids or I wouldn't have replaced them, but they definitely aren't bad. Of course, then I'll have some nominally 8 ohm speakers mixed with 4 ohm speakers which I'm betting would be kind of tricky toget working just right. On the subject of adding though, I am kind of floating ideas around about something in the back. While adding anything to the front would require some much more major modding, the back is a much more viable option. There's a decent bit of room between the metal of the frame and that material they've put over it (it has some sort of compressed poly material on the bottom that's fairly solid and over that is a sort of carpeting material, so it's possible to cut a hole -- as I already basically did for the rear speakers anyway.) Mostly I'd just need to come up with something to protect the speakers in case someone should ever unthinkingly set something in the back (though since it's a modern car no sensible driver would put anything back there since modern cars have so much less visual range out the back as it is) and that would probably be sufficient as far as adding. I think it might sound good enough. In fact, the rear speakers are most important in this car because the front speakers are only just above the floor. The left one is blocked largely by my own feet and the right one sometimes is blocked by stuff I've put down plus just plain has a bad angle. I'm still not sure that this would work well though. Even there I'm not sure how well it would work without appropriate holes in the frame itself (which is probably not very viable as it's a pretty tough metal.) I'm also still thinking about someday building a proper enclosure and setting up a subwoofer and all, but of course can't afford a proper amp or anything like that now, so this puts a crimp in the subwoofer plan. Anyway, basically, if I'm understanding the point of the article correctly, the idea is not to increase the volume/power/etc of the mid-ranges, but to force our brains to more specifically focus on the wanted audio (eg the music rather than the noise of the tires, sustained engine, and etc.) I think he has a good point because those noises do indeed add a noise floor to deal with with the music and the two can kind of blend to the mind. Increasing total volume is generally not an ideal solution anyway, so I like this idea even better still, regardless of the monetary issues involved in the loudness method.Driving a 2006 Saturn Ion (2)

Still stock everything, including head unit (no extra amp) with cheap SONY four ways in the front and less cheap Infinity two ways in the back.