THANK YOU THANK YOU THANK YOU!!! I have also been trying to figure out this Bose notch filter through google images and that AK post but I wasn’t sure if I had it right. I bought what I thought was a pair of 101 Music Monitors new in the box for $25 on CL but when I got home I found out that they were part of a Bose proprietary music system with the 1 ohm drivers wired directly to the input terminals - no crossover and no matching xfrmr. Naturally Bose doesn’t publish their schematics so I’ve been searching for the notch filter info, and here you show up with virtually the same project I’m doing. I had the values down but hadn’t built the circuit yet, so now I’m gonna sit down and do it. I think the Music Monitors use a little poly foam in the cabinet to dampen the resonance so I’ll do that too. Again, thank you very much!!
I loved watching this project. While I recognize the shortcomings of Bose products, I do find it fascinating to deconstruct and understand what they were up to. My only comments would be, (1) I would have used some hot glue to hold the crossover components together, and (2) I would like to have seen before and after measured curves with pink noise. it's pretty cheap these days to take those measurements with a calibrated mic and an ipad. Thanks for sharing!
Honestly Colin, I really think you should do more audio projects like. Though personally, I'd really enjoy it if you did educational videos on building crossover networks and using components like you did in this project. Give us a little more of that, you're a natural at teaching!
Great video! I'd love to see more of this nature. I made a similar home made sound system. I found an old bookshelf speaker from a hi-fi system. It already had a mid and tweeter, so no need to modify the guts. I used the mono full spectrum (w.o. bluetooth) version of the amplifier you used. I got a 24v-6amp power supply and it can really push a lot of sound out the the speaker!
So at 24:30 you place a ferromagnetic screw and washer into the air-core inductor, which is going to both considerably increase the inductance and add lots of eddy-current losses to the otherwise high-Q inductor. Probably going to soak up lots of HF power and distort your desired response. For air-core inductors its important to keep metal components well clear.
Mark Tillotson there was room to space all those wire wound components so that their magnetic fields interacted less. Then putting all that ferromagnetic washer and screw through the air core was a waste of an air core in an inductor. Insightful video though!
That is a very easy to understand way to explain that to people who don't have allot of electrical engineering experience. Also respect for utilizing the 3R's no matter how much flack you might take for the speakers. I personally don't have a problem with Bose. I have owned a fair amount of home audio gear and although I think it's priced high, I never had any issues with my Bose equipment. Good video!
Also, your speaker sounded WAY better. In my opinion of course. Would love to see more videos of this type!! Do a car audio install perhaps?? Thanks Colin
I have a 1995 Mercedes S320 with the BOSE sound system, and the doors have the SAME three-screw drivers installed in them inside a special box. Same for the 2001 Audi S4 I worked on. Pretty unimpressive. They DO sound great though.
Even without blood this was a good watch, more audio please. I first found you with your headphone mod video, and now find myself getting interested in stuff I was totally not interested in. 😂 Congratulations on 100K
Great little speaker mod project, though, maybe, you could have sourced a pair of old used tweeters out of a blown speaker set, drilled a hole, mounted them in and made a crossover circuit??? Maybe for the future... 🤔🤔😏 👍😎🇬🇧
My Local Autowrecker is a you pull type, basically speakers are $5 each any size or make you go and get them, I did some Bose speakers, 4ohms they had tons, would of costed $10 to replace those 1 ohm speakers with 4 ohms. But I guess it wouldn't as been so fun :)
I had a very similar amp connected to a pair of Bose 101's on my 2nd PC, the sound was really thin & tinny, I replaced it with an Audioengine N22 amp a couple of days ago and the difference is remarkable, it's actually worth listening to now..!! Great video, I clicked on it when I recognised the amp, when you said "some of you may recognise these" I was like "no effin' way" lol..................
I have a pair of "Lifestyle" active speakers (101's with a built in amp) that sound amazing, they have been my main PC/TV audio system for over 22yrs..!! Best bargain I ever had at $250 brand new & discontinued, they were about half price here, at the time..!! (Australia)
Why is it frustrating? His designs were unique and very successful! That is not the same driver as the 802-Series III or IV. And it’s also not the same driver used in the 901. Those speakers were engineered specially for the model! The 901 is a incredible speaker. They put more research and engineering into the driver than most manufacturers put int their entire line.
Typically you can estimate the speaker impedance by multiplying the DC resistance (which is what normal multimeters measure) by 1.33. For example, your meter reads 6 ohms the speaker impedance (AKA AC impedance) is pretty close to 8 ohms. In speaker spec sheets you can find this listed as "Re", or simply listed as DC resistance. I looked up a Wavcor 4.5" 8 ohm full range speaker, which has it's Re listed at 6.5 ohms
Great video about making a speaker sound better. More videos about this or any other tech topics would be great. Multimeters are strange when it comes to measuring resistance, especially for audio purposes, but they would give you a value that can be helpful if you think that the "audio impedance" should be different, just use a mathematical function to take the measured value in the multimeter and get the value of the audio impedance.
I use 101s in my garden, I also have 4 of the ones you have here with the transformers inside. Require a controller as there is no crossover. I like the 101s, I have "good" hifi gear as well, but I have no issue with Bose gear in all honesty.
Bose only gets static for their unconventional design practices and their high price for the apparent cost of the materials they use, but they are not "bad" speakers when used for their intended purpose. The use of a single full-range driver won't deliver the top octave from 10kHz to 20kHz, but the 101 design and the other similar single-driver professional audio products are very robust and reliable, which is why so many of these speakers remained in service for so long.
This looks like some PA speakers. If I'm not wrong, they normally drives them by higher voltage, perhaps to save on copper since it can be a long run of wire. And depending on the size of the space the spkr is serving, they can adjust the output power using the taps of the transformer.
My two cents is - 1} In my area, there are electronics recycle bins (mostly at township public works facilities), or as I call them, dumps, where people drop off their old stereo equipment. I have found many a treasure in those bins! You can pick up a decent old stereo receiver for free - why would you spend money on a cheap Chinese amp, even for a garage system? 2} I remember when I was poor and in college (70's), that I used to scavenge amps, speakers and other things from trash piles to build things for myself and friends. But electronic equipment was so much more expensive back then. (That's why people just throw their shit away now without thinking.) The cost of your time for anyone who has a minimum wage job is more than the effort is worth. That's why Radio Shack and Lafayette went out of business. 3) But, I have to admit...if you're retired and have nothing else to do (like me)...then it's like creating art from trash. 4) I only buy Bose second-hand stuff I f I see a STEAL...like the Cinemate series 3 sytem I got for $50 on CraigsList! Great video that covered a lot of subjects!
Liked "I know you guys are gonna give me shit in the comments" Haha. Very informative and explained well IMHO. love covering audio, welcomed by this subscriber.
If you aren't looking to pick apart the speaker performance, then Bose are perfectly fine, nice even. They're not spectacular, but they're very clever and can make acceptable to decent sound. If you don't have space for larger speakers, then Bose are your best bet, really. If you have more space, then feel free to find anything else that you prefer more.
Back in the 80's and 90's we said, "No High's, No Lows: Bose" They are great at reproducing midrange (and back then audio reinforcement was VERY poor at reproducing the mid frequencies!). The great thing about subtractive EQing is that your not going to have as much distortion added to the signal (although it may have some distortion added because of the components?). Yay...Dayton Audio the new Radio Shack of audio electronics. I think I would just put in a tweeter anyways - a Dayton RIBBON tweeter. I've never heard one so that's why I'd give them a try. @30:44 impressive. Not bad for a small no budget project.
Spot there for tweeter should added a small dome tweeter ! has pair of 101 Bose I added a two way cross over and tweeter. Sounds awesome now or at least I thinks they sound awesome
I have a set of Bose Acoustimass 3 Series II's and I love them. I've always wanted to own Bose as I have heard their amazing sound when I was a younger lad. Never could afford them until a few years ago. I picked them up off of eBay for $85 and have used them ever since. Not a big fan of their radio's though. Don't get me wrong, they sound amazing but I was able to get better sound out of a one speaker Tivoli Model One. Really want to get another Model One sooner than later.
I don't mind bose products. they sound fine. they love to use EQ and I think most of their speaker EQ's sound pretty decent. if you got them for free then it's absolultely not terrible. nothing gained, nothing lost. I have a pair of QC15's and I love them.
With the issues of running lots of cable , possibly hundreds or thousands of feet. Would it be possible to use the negative and earth of the mains circuit to feed the signal to the speakers ??, or is there an interference issue ?? For me the modified were to tinny , took out a lot of the bass , but we are all have different tastes different and everyone's hearing is different so its a case of whatever you are happy with
Very late to the party, but this is just not what the resistor does in a frequency crossover. The resistor sets the base timing for your capacitor and inductor to work off of. They will just do nothing with the signal itself - especially not with the midrange - other than setting the tau for the rest of the components. I like your explanation otherwise, but that part bothered me. Anyway, thanks for the video. Very much enjoyed it! Edit: Filter network, not frequency crossover - of course.
Very interesting video! I got a pair of Bose model 25 speakers which look very similar to these and a friend of mine let me have a 70v Line amp which runs them nicely but I don't have a Bose system controller to run them so they are very lacking in high end and low end. Can I adapt what you've done to add the eq curve while still running at 70v?
Still sounds as if it needs a tweeter. You could add one with a small network of a capacitor and a resistor. Shame you didn’t show it in combination with the little class D amplifier you corrected.
adding a screw in the middle of the coil might not be a great idea. it increases the value of the coil. :) might not be a big deal in this case. but the thing you calculated might be off now.
I have a set of 101 s which were once an active speaker set. I bought them very cheap. when I opened them the electronics were missing. I also had a faulty active acoustimass sub which I repaired. I connected the 101 s directly the acoustimass . The sound was ok. I carried out your mod but left out the 4 ohm resistor. The sound is fantastic . I was thinking about trying to graft in a tweeter on the 101s But they do not need it with this mod. Thank you for your investigations.
Why is it that Home Audio system that can utilize great amount of power usually dont use high impedance drivers while small personal EARBUDS that generally relies on battery go to as high as 600 ohms?
cool video, not sure if you can help, I have 3 bose speakers from an "acoustic wave music system" and would like to make a speaker with them. but i can not find any info on how to do that.
LOL, "you guys are gonna give me shit.. LMAO. Well, I wont do that, but I will say, even though I'm one of those guys who loves to hate Bose, I must admit a friend of mine has those same speakers that he added a soft dome Audax tweeter to, (crossed very high around 7khz) and uses them with a subwoofer, using an old school Marantz 2275 receiver, and I was exceptionally impressed with the incredible sound, realism and depth of the finished product. As much as I think most Bose products are sensationalized, exaggerated, and by and large, mostly overpriced junk, the world renown 901 speakers that have been made for decades are legendary. As a young kid, I knew a guy who had the Series II's with the active equalizer many years ago, and recall them sounding like God back in the 70s, and inspiring my first love for Hi-Fidelity. Never been a fan of much of their newer stuff like the Lifestyles, or Acoustimass, or even some of their other mediocre creations like 10.2s, 201s, 301s, 501s, 701s, etc, but you will never hear me knock the 901s. Few speakers generated more interest, or perpetuated more controversial stir and debate. It's t Bose's hallmark speaker, and many within audio circles still consider it legendary, and to be a hi-fi standard by which others are compared. And they certainly have a loyal following, so they can't be all that bad.
Don't you lose a lot of sound power across the 4 ohm resistor? Under this condition, the 1 ohm driver only gets about 20% of the voltage being fed by amplifier. This translates to about 4% of the amplifier's power actually being used by the driver, the rest gets burned up in the resistor.
It's really non-trivial to do this right. Anyone can buy a 2-way crossover off the shelf. But to do a proper blend between the mid-woof and a tweeter, taking into account their impedance, sensitivity, phase, and natural acoustic roll-off -- and thereby, making it actually sound any better -- takes a LOT of measurement (acoustic and electronic) and modeling. If you DON'T do any of this, then you're blending the two randomly, without any regard over their frequency response, phase alignment, and relative loudness between the two drivers. That's likely to be worse than just the full-range 4" driver alone.
@@nickguy6820 i agree with you, although it's not all that difficult to achieve with a couple meters and if you know how to build a x-over. But for a garage system these are just fine the way they are. Bose has already tuned the enclosure to provide a full range response from that single driver. It's no audiophile setup for sure but given the budget and cost I see no reason to do anymore work than Colin has done here.
You need a reasonably well calibrated omni test mic, a sweep test signal and something to analyze the mic input to show you the response. You might also need something to window that response so you're not getting crazy room reflections in your measurements. You also need an LCR meter that can show you the impedance curve, and preferably a speaker testing setup to give you real-world T/S parameters and not just the published specs (which may be close, or may not be.) Once you have all of that data, you can import it into a modeling program and tweak the simulated electronic components in your crossover until you get a somewhat smooth and symmetric roll-off on either side of the XO point. Ideally, your phase is matching up as well, although sometimes you have to choose between response and phase and compromise on the other a little bit. You may have to address peaks, notches, resonances, and other uglies. The less ideal the driver (or its enclosure), the more this becomes an issue. You will have to make decisions on whether to optimize for XO point or tweeter protection. Now you can build the XO and see if it performs according to the model. Tweak, rinse, repeat. Sure, you can skimp on any of these steps. But when you do, you end up with random (well not truly random, but unpredictable) results that may or may not sound better or worse than if you had not bothered at all. At best, you will have imperfect transitions. At worst, you will cause your amp to oscillate or ruin a driver. Point is... XO design is more than applying textbook filters to ideal drivers. It's a complicated process with equal parts art and science and dumb luck.
Typical low-impedance speakers are (relatively) low voltage and high current. Commercial systems are (relatively) high voltage and low current. The actual speaker (the driver itself) is often the same, with an external transformer to do the impedance conversion. To get this thing to provide reasonable output in stock form would take an amp that outputs a lot of voltage. Which means either a commercial amp that is designed for 72V systems, or a big monster amplifier that doesn't mind high-impedance loads and can put out enough voltage to brute-force the same loudness out of that speaker -- and that's rather wasteful, since it will be built for 1000W output or so, and you don't need that kind of iron for a garage.
Normal People: Yeah, Bose might not be the best choice, but they do sound decent enough and most people dont really care abaout the differences. Audiophiles: How dare you to defile the Audio-Gods? Your punishment will be 30 wippings, WITH COPPER CABLES HAHAHAHAHA YOU DESERVE THE WORST FATE POSSIBLE and we will force you to listen to Justin Bieber THROUGH AIRPODS MUAHHAHAHAHAH
Whats your opinon of the parts an the re-construction of the work,mods That Danny richie of G.R. research does? He got his followers thats for sure.....
Class D is actually more sensitive to this than Class A/B. For one, the output network is tuned with reactive components (relatively large capacitors and inductors) to work at a specific impedance. Or, really, to work acceptably within a range of impedances -- since speakers are not exactly purely resistive. Whether the amp has sophisticated current-limiting to prevent damage with excessively low impedance loads has very little to do with its topology. You can implement current limiting in any class amplifier. If you don't, then Class D will suffer in exactly the same way -- excessive current through the output transistors, and possible thermal damage as a result.
they are not all the same types. there are made out of different materials, they have all different surrounds. (cloth material in the older ones and in the outside speakers) .... the 902 have totally different drivers........
20 years ago I got a cheap pair of Videomates - the same as the 101 but with a 30W amp inside. These are just powered speakers, not active. Later, now 10 years ago, I got two pairs of Roomates (different label and in black) for surround sound from a PC for about 40 GBP a pair a huge drop from the 500 GBP in the review of Nov 95. They have proved useful for monitoring sound when converting old video and old analogue formats and to carrying around to check out other systems. www.mcmullon.com/icollect/hi_fi/bose/pc_pro_199511.jpg
Your making something to complicated.pick up a 4 channel amplifier,run new wire to speaker location and set up the system the way you want.discad any equipment left there and use the good speakers you already tu up.
A very inefficient way of modifying that speaker you get less than 1/7 of the power that you get to use if you add a simple transformer to the output of your amplifier you have no loss
