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Bad DQ-10 tweeter (the one with the fuse)
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I have a?Bad DQ-10 tweeter (the one with the fuse). I would like to know if anyone has one to sell. If not, does anyone know the part number of the OEM tweeter, or a part number of a good replacement. I fact I would like to know the part number of all of the speakers and components please.
Thanks, Rich |
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I have 4 spare tweeters on the board. You can contact me via messenger PM On Wed, Apr 6, 2022 at 2:16 AM rbelcke via <rbelcke=[email protected]> wrote: I have a?Bad DQ-10 tweeter (the one with the fuse). I would like to know if anyone has one to sell. If not, does anyone know the part number of the OEM tweeter, or a part number of a good replacement. I fact I would like to know the part number of all of the speakers and components please. |
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I have the panels or boards. Let me look for the images . They are in storage.? On Mon, Oct 31, 2022 at 2:33 AM Ed Marrs <ed.marrs123@...> wrote: Hello Richard, Do you still have an available DQ-10 tweeter.? Mine is not working, although I measure an 3.7 Ohm? impedance across the terminals.? I have trying to drive it independent of the cross-over, too.? But still not hearing any tone at 12 KHz,? |
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Hello Richard, No rush.? I’m still troubleshoot the circuit and it may be possible that it’s the crossover.? I’m waiting for caps to come in from PartConnecxion. Thanks for looking to see if Tweeter’s are?available. -Ed On Mon, Oct 31, 2022 at 6:59 AM richard adelberg <richardadelberg@...> wrote:
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I have a set of unmodified original yellow cab crossover’s for the dq10’s if you want to simply try another crossover On Mon, Oct 31, 2022 at 10:23 AM Ed Marrs <ed.marrs123@...> wrote:
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I think you said in your previous email that you hook the tweeter up directly from your amplifier speaker leads and you got no sound if that’s the case hooking it right up to the speaker wires from your amp if you’re not getting anything then it’s no good On Mon, Oct 31, 2022 at 10:25 AM richard adelberg via <richardadelberg=[email protected]> wrote:
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Richard, Thank you for the offer.? I also have the unmodified Left channel that appears to be working well and can be used for comparison.? I only came across a difference between Left and Right while attempting to plot crossovers frequency performance and before I updated the crossovers with new caps.? I wanted to be able to do an A/B comparison (before and after) after the mod to see any improvements were made.? The Right channel tweeter just doesn’t appear to be drawing any current (no voltage drop across it when operating at high frequencies.) and unlike the Left channel tweeter. - Ed On Mon, Oct 31, 2022 at 10:25 AM richard adelberg <richardadelberg@...> wrote:
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Yes, I did say that.? However, I repeated it again this morning and I hear it faintly.? Part of the problem is in hearing the high frequency and the other is that I’m being cautious not to directly drive it to hard.? For the direct measurement, I am using a 100mv ?pk-pk 12KHz sine wave generator whose output impedance is 50 ohms and placing 50 ohms in series with the tweeter.? This is perhaps too low a test signal.? Increasing the voltage a bit more, I hear the tweeter faintly.? I think I may next disconnect the Stweeter that is in parallel with the tweeter to see if I can get the tweeter to draw some current in the crossover network at high frequency. On Mon, Oct 31, 2022 at 10:27 AM richard adelberg <richardadelberg@...> wrote:
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[....]If an ohmmeter or a multimeter is measuring a resistance of 3.7-Ohms across the tweeter's input terminals, then the tweeter's voice coil is drawing current. Otherwise, the ohmmeter or a multimeter would display a measured resistance of infinity Ohms (an open circuit). For testing purposes, I would be skittish about connecting the tweeter directly to the output terminals of an amplifier, unless the amplifier had a very low output-power rating... a couple of watts at most. I would rather use the output terminals of a signal generator. Also for testing purposes, I would set the signal generator to produce a signal with an output frequency of, say, 2 or 3 or 4 kHz, not 12 kHz. Richard, Thank you for the offer. I also have the unmodified LeftHave you tried temporarily swapping the tweeters? If the "bad" tweeter suddenly starts operating normally when it is installed in the "other" speaker system, then the fault must lay not in the "bad" tweeter, but rather in the crossover network of the speaker system from which the "bad" tweeter was (temporarily) removed. J.J. McVeigh, Attorney At Law Butler, Maryland USA Practice before the Federal Communications Commission Member: NY, DC, and USPTO Bars |
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I don’t know I’m not as scientific as you are. When I have a driver that I suspect isn’t working I simply take the driver and I hook it right up to the speaker wire coming from the amplifier or the receiver that one says you have to turn the volume up very loud it’s pretty obvious one an FM station or any music whether the driver is working or not that tweeter can produce sound from 3000 to 12,000 Hz. It’s really not that complicated it either works or it doesn’t On Mon, Oct 31, 2022 at 12:06 PM John Joseph McVeigh <kd4vs@...> wrote: > [....] |
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On Mon, 31 Oct 2022 11:28:24 -0400, Ed Marrs wrote:
Yes, I did say that. However, I repeated it again this morning and II am not surprised ihat you can barely hear the tweeter if you are driving it with a 100-mV p-p signal that must pass through a series resistance of 50 Ohms. Using the simple equation for a resistive coltage divider, the voice coil of the tweeter is seeing only 6.89 mV p-p of resistive power. Assuming that the drive signal is sinusoidal, that corresponds to 2.44 mV rms, or 1.6 mW of resistive power. (If you are using an Ohmmeter or a multimeter that measures resistance rather than impedance, the 3.7-Ohm reading that you are getting does not include an inductive component. So, we don't know what the reactive power that the tweeter is seeing is.) The tweeter should be able to handle, without any risk of damage, at least a Watt or two of signal power. If you have a small battery-powered transistor radio with an 8-ohm earphone jack, you might consider using the radio as a test signal source for the tweeter. Just wire up a two-conductor test cable with a miniature or subminiature phone plug (whichever the radio wants to see) at one end, and connect the free ends of the two conductors to the input terminals of the tweeter. Turn the radio's volume control to its minimum setting before turning the radio on, then turn on the radio, and gradually turn up the volume, and see (that is, hear) what happens. J.J. McVeigh, Attorney At Law Butler, Maryland USA Practice before the Federal Communications Commission Member: NY, DC, and USPTO Bars |
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Sorry, MISSED THE COMMENT JUST ABOVE!
Ed, with 100 ohms drive impedance you are only getting 3.7/ 103.7 of the signal greater voltage to the tweeter. Since power is V ^2/R even with a 1 volt drive level at the generator you are getting less than 1mWatt to the tweeter, so not very much power at all. With a 90 dB sensitivity tweeter that would be an output of only 30 dB, barely audible even with a good ear at 12 kHz. ?I would suggest you eliminate the 50 ohm series resistor and repeat the test?at a frequency more audible to ears, say 5 kHz. You can even set it to 2 kHz safely, just start at a low signal level. I also suggest you eliminate all other unknowns by pulling the tweeter fuse and just connecting the signal source directly to the tweeter terminals. Note most of the people over 65 that I have tested can not hear much above about 8 KHz at low levels (threshold). If you are curious there are many APs for phones that allow you test your hearing with reasonable accuracy. On the iPhone I recommend Mimi. |
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John,
I agree that that the tweeter is not open and draws DC current with an Ohm meter.? However, in circuit and connected to the crossover I measure no voltage drop difference across the tweeter when I apply low or high frequencies to the speaker from a power amplifier, as I do with the other speaker.? For the direct measurement of the tweeter I am using a signal generator with 50 ohms output impedance with 50 ohms in series with the tweeter and not directly with a power amplifier. Perhaps too low a signal. However, I do faintly hear the tweeter working.? I will try with low frequencies, as you say.? ?? I am plotting the cross-over response of the tweeter by measuring the ratio of voltage applied to the tweeter to the voltage applied to the speaker.? And not seeing any significant voltage drop (using a DVM measuring mv rms in parallel) or current delivered (using a DVM measuring micro-amp rms in series) to the tweeter at any frequency, The voltage measurement is made across the tweeter terminals and current measurement made across the fuse terminals, with the fuse removed of course.? I like you idea, about swapping the tweeter and will try. Thanks, -Ed |
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Charlie,
Thanks for the comments and suggestions.? For the direct tweeter measurement I was a bit worried about loading the signal generator down with the 3-4 ohm impedance of the tweeter.? This was my reasoning behind the 50 ohm series resistor.? I agree I should try feeding it a bit more power (perhaps a bit more voltage) and as you say a lower test frequency for the hearing impaired.? I was thinking of getting my dog to help me with this. Thanks, -Ed? |
开云体育Ed no need to worry about loading the sig gen. It should be able to tolerate even a direct short on the output if it is of reasonable quality.?One reason to use the lowest impedance possible is that the tweeter impedance varies with frequency, reaching a high value at reasonable around 1 kHz as well as rising at higher frequencies. Thus the acoustic out of the tweeter will rise as the impedance rises due to the voltage divider rule (AC). It is also Ok, just to test whether it is working or not, using it as you have but just wiring direct and cranking up the voltage. However, unless the dome is held rigid, by hardened glue for example, ?just measuring the dc resistance tells you the voice coil is ok. Charlie Conger On Oct 31, 2022, at 12:31 PM, Ed Marrs <ed.marrs123@...> wrote:
?Charlie, Thanks for the comments and suggestions.? For the direct tweeter measurement I was a bit worried about loading the signal generator down with the 3-4 ohm impedance of the tweeter.? This was my reasoning behind the 50 ohm series resistor.? I agree I should try feeding it a bit more power (perhaps a bit more voltage) and as you say a lower test frequency for the hearing impaired.? I was thinking of getting my dog to help me with this. Thanks, -Ed? |
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Yep, unfortunately my ears aren't what they used to be. And it helps to have a sound pressure meter on hand. And definitely suspect the fuse first and replace it just to see if improvement occurs. A few years back I switched to .75a solder tail fuses due to past fuse holders creating extra series resistance . They do blow if you get fairly carried away but to date haven't harmed a tweet. But those days of pushing the limit are fading at my age. Nevertheless, I'm in the process of tossing together a parts order from China and noticed that .80a fuses are available. So we shall see in a few months.? Second suspect would be a bad solder joint on the xover. If you haven't done so resolder the board. IMHO, film cap issues are rare. But it can't hurt to run them all on a decent ESR cap meter. I usually use a PEAK brand but just recently acquired a cheap Chinese multi-device tester. The design with the locking lever test socket on the front. It's truly amazing for the price and it's debatable if it isn't better than the PEAK.? So if your lucky the tweet is still good. In fact you might consider removing the cone to inspect the voice coil and the condition of the gap. Perhaps something is jamming it up. Like dried up ferrofluid or rust or something. I have yet to encounter OEM tweets with fluid but perhaps someone added it in the past. And it has hardened up. Best wishes, DD On Mon, Oct 31, 2022, 11:50 AM Charlie Conger <ctconger@...> wrote:
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On Mon, 31 Oct 2022 10:13:22 -0700, Ed Marrs wrote:
John,If the tweeter draws current from a d.c. source, e.g., an Ohmmeter, it will simply have to draw current when connected to an a.c. source. It is physically impossible for the tweeter's voice coil to draw d.c. but not a.c. The amount of current drawn in the case of a.c. will, of course, vary inversely with the frequency of the a.c. source, because the impedance that the voice coil presents to the a.c. source contains not only a resistive component (due to the inherent Ohmic resistance of the wire that comprises the voice coil) but also an inductive component, and inductive reactance increases directly with frequency. The tweeter is modeled as an RL series circuit. There may be a tiny amount of stray capacitance as well, but it is surely so small as to be safely ignored when it comes to performing a circuit analysis. J.J. McVeigh, Attorney At Law Butler, Maryland U.S.A. Practice before the Federal Communications Commission Member: NY, DC, and USPTO Bars |
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Charlie, thanks for your comment.? I was about to respond that I checked both Fluke DVM ratings and one is rated to 100 kHz, the other 200 kHz.? This was an original concern of mine when I decided to use the DVMs for the rms voltage measurements, instead of an o'scope.? I even checked one DVM to make sure and it was okay.? However, I had not check the other since its rating was 100 kHz, but your comment prompt me to do so.? Using a 50 mv rms signal generator output and the DVM rated for 200 kHz, the direct voltage measurement varied from 50 mv rms to 47 mv rms going from 20 Hz to 20 kHz.? On the DVM rated for 100 kHz, the measurement varied from 50 mv rms to 10 mv rms, going from 20 Hz to 20 kHz. Now, I suspect that this must be the source of my confusion about the operation of the tweeter.? Thanks so much! - Ed
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Charlie Conger
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