I've still got an audio power amp that's better than my somewhat expensive speakers. Haven't blown that up yet.
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
So. I guess the LM383 is the model of the design for this. Won't do 10V p-p into 2 ohms. Set it up in bridge mode, with two, maybe? Rochester or Jameco. About $5 each.
Ok, thanks for that; it looks interesting. I suppose R5 should be 5 or 10W? (The speaker is only 2 ohms because it is wired in series with a 2 ohm 10W resistor. Otherwise it has I-don't-know-what impedance in operation; it's just a ribbon so it's basically 0 ohms to DC.)
speaker
As I explained in another message, the input is the signal generator in my DSO. It puts out a 1V signal, and I have no idea what the impedance of the circuit. I am guessing that the resistor divider you refer to is what I call a trim pot, and I have a couple different ones so I should be able to adjust the input signal as you suggest. Now that you've put it in those terms I now surmise that part of the signal distortion that I was seeing earlier was a result of misusing the trim-pot.
I suppose there may be an issue because the signal generator and probes share a common ground...
The 5.1 ohm resistor is normally wired in series with the speaker when it is installed in the cabinet and hooked up to the crossover. In this setup, I'm using 2 ohms because I don't have a 5 ohm resistor beefy enough to handle the power that was coming out of the original broken circuit. I assume it is just ballast to give the amplifier something to push against.
I'll see about wiring this up later this weekend and giving it a try. It looks simple enough that I ought to be able to figure out what does what without too much difficulty. 50kHz is the target frequency for testing and experimentation since my workbench is in a closet and I don't want to destroy my sanity by working with audible frequencies, but in practice I may want to use 1 or 2kHz when testing the final product.
Thanks again!
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
Yeah, I noticed the clipping. In practice, explained in my reply to your previous post, I was assuming a 'beta' of 50, which may be trueish of the 2N3055, but is clearly unreasonable for the 2N2222.
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
+-----+ | | +-----+ | | |R| | | | | |i| | | | M | |b| | M | | a | |b| | a | | g | |o| | g | | n | |n| | n | | e | | | | e | | t | | | | t | | | | | | | | | | | | |
+-----+ | | +-----+
--------+ +-------- | Terminal |
-------------------
I've left out some of the chassis. The two magnets are on the ends of a cast-aluminum 'horseshoe' that wraps around the back of the driver. The terminals as shown above are about 2x2x5/16" slabs of aluminum with a slot machined in the front where the ribbon is affixed with a small block and Al screw. Physically, the gap between the magnets is
9mm and the ribbon should be slightly smaller. The magnets are electrically isolated from the terminals. The ribbon is crimped along its length to facilitate movement.
What he said.
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
Yeah, except in my case, I have used copper leaf (used for gilding) to fit in the two spares I'm fooling around with. It's incredibly difficult to work with, such that the shape I impose on as with the diagram referenced above is so fragile that it can be destroyed by bug farts or heavy breathing. I may have to locate something slightly thicker to make it practical.
The bonus with the thin stuff is that it produces incredible detail.
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
It wasn't wasted time if you learned something. I know that most here just think me to be a harsh asshole... but I'm trying to teach thoughtful analysis of circuits and get folks to drop the hand-waving BS. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Yes, I learned to not write at night. hehe. I already KNEW what you had to rub my nose into, though. I just wasn't engaged in considering all the issues. Had blinders on. Oh, well. There is a lesson there, too.
I've been looking at this circuit, and I don't see how the input to the base of Q3 can be reasonable unless the output of Q1 is kept so low that it doesn't go over a volt or so, in which case what's the point of having it?
In the previous circuit I was using, the intent of Q2 (Q3 in your circuit) was to boost the current of the signal from Q1, however I was apparently working with bogus information from a web-page that posted circuits that don't work (i.e. Figure 16).
Are you sure you didn't rattle a bunch of components in a metaphorical box and then open it to produce the above circuit?
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
Correctly wired, this sucks big fat donkey dick. When the base of Q2 goes over 1.2V or so, the signal turns into hash with slight overtones of signal. It only 'worked' when Q2 was wired with collector to ground and the emitter wired as above and connected to R3. Q3 had bubbled some molten something out of the case, and dissipated a huge amount of power, but drove the speaker fairly hard. Go figure.
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
OK, I've just got to ask: Why not simply use the power amp to drive the tweeter? The amp frequency response may not be flat to 50 kHz, but you don't need that here. The amp probably puts out something like +/-20V, so 50 kHz can be well down on the roll-off and you'll still have plenty of moxie to fry your tweeter. (And if you are only trying to use a frequency high enough to be inaudible, something closer to 20 kHz will probably be just fine too... unless you are a very precocious child, or you eat a lot of dog food.)
OK, maybe you don't want to pull the amp from the stereo installation, if you expect the tweeter development to take a long time, and you want to listen to music before it's done. In that case, you can build a pretty decent power amp using quasi-complimentary 2055s (or any other NPN power type). You use one in a more-or-less conventional Darlington with a small-signal NPN drive, and the other with a PNP driver.
This configuration was pretty standard before decent complimentary power pairs became readily available. I imagine that Googling on "quasi-complimentary power amp" will get you lots of circuits. When true complimentary pairs arrived, quasi-comp got a lot of bad press. But the old design wasn't really bad: Back in 1973 I made a unit using an old Delco Radio app note and subbed 2N3055s for their part, and at 40 watts per channel into 8 ohms it had
0.06% THD at 1 kHz, rising to less than 0.2% at 20 kHz. (Tested by Marantz techs at a local stereo store, on tour with a rack of test equipment to demonstrate how much better Marantz was than whatever you brought in. We each got a nifty test results certificate with THD plot of our amps to take home.)
Best regards,
Bob Masta DAQARTA v7.21 Data AcQuisition And Real-Time Analysis
formatting link
Scope, Spectrum, Spectrogram, Sound Level Meter Frequency Counter, Pitch Track, Pitch-to-MIDI FREE Signal Generator, DaqMusic generator Science with your sound card!
ATM, I only have one amplifier and preamplifier and basically, I would prefer to learn something rather than throw money at the problem. Analog electronics is on my 'to-do' list, which I why I purchased a scope and some parts a little while ago. In fact, I'm more interested in embedded systems programming, but of course analog electronics is how those things interface with the real world.
The tweeter development is done for all intents and purposes. The tooling to cut and form the ribbon is made, so I can turn out nominally identical parts with relatively little effort. The amplifier is really only needed to break it in a little (mostly important for a thicker material than what I am using currently), which can be done in-system but I was getting tired of swapping tweeters and listening to crap sound while experimenting.
It looks as though I just need to find some electronics basics tutorials that will impart the knowledge I need to acquire, as opposed to bogus sites that contain lots of misleading information. Once upon a time I had a copy of TAOE, but lost it due to circumstanced beyond my control, and before I had time to study it much. I'm sure I'll figure something out before long; after all this isn't rocket science.
Regards,
Uncle Steve
--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
Yup, both full of Bad Info presented with confidence. The first guy is smarmy besides, coming over all superior about current flow vs electron flow, as if it mattered for solid-state circuit design.
That looks a lot like a circuit that I built when I was 10, out of a book of projects (that would have been early 1970). It sorta worked, kinda, but ate batteries like mad. (It used a TR01C TO-3 package germanium transistor, made by International Rectifier. It also had a carbon mic so it didn't need a preamp.)
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.