- Can I use Pizeo Tweeters, or???? - 5 Updates
- What is this mains connector for? - 7 Updates
- LED VU meter problem - 3 Updates
| Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: May 06 10:32AM +1000 >>> Piezos are not the 'junk' some opine, >> **Oh yes they are. Absolute crap. > that's not a sensible factual claim **Absolutely factual. They're shit. They are down there with the worst HF drivers available. > I already know how they work, and have constructed experimental > speakers using piezo technology. I don't wonder that they work, the > principles are well known, and have been for a long time. **Indeed. However, the reality is that the performance has always failed to live up to the hype. >> high quality audio application. > 'high quality' is a bit too vague there. They're good enough for the > average domestic hifi. **I guess we have different ideas on what constitutes 'average domestic hi fi'. One local manufacturer decided that piezo tweeters were a great idea for his speaker systems. He crossed them over correctly and used a parallel resistor to ensure the whole thing worked correctly. I used to replace the piezos with a nice dome tweeter (after modelling and correcting the crossover to suit of course). The result was far more satisfying. The speakers cost (as I recall) around AUS$1,200.00/pair. That is what I refer to as 'average domestic hi fi'. >> will have exploded years ago. > Maybe you should tell that to the amp I had that couldn't drive them > stably without a resistor. It's clearly not factual. **The average capacitance exhibited by piezo tweeters is between 100nF and 250nF. Any amplifier incapable of dealing with those amounts of capacitance (on the end of a speaker cable and crossover) does not deserve to be called an audio amplifier. It is no better than a door-stop. >>> power. >> **Much, MUCH less than that. > Percentage does vary according to the music. **Of course. It is still MUCH less than 20%. More like 5%. -- Trevor Wilson www.rageaudio.com.au |
| tabbypurr@gmail.com: May 06 12:14AM -0700 On Saturday, 6 May 2017 01:32:21 UTC+1, Trevor Wilson wrote: > **Of course. It is still MUCH less than 20%. More like 5%. > >> However, as Phil stated, they still respond to bass frequencies and > >> thus benefit from a crossover. I hoped you'd come back with some facts. NT |
| Phil Allison <pallison49@gmail.com>: May 06 12:47AM -0700 Trevor Wilson wrote: > **Absolutely factual. They're shit. They are down there with the worst > HF drivers available. ** Even a $20 Tandy horn was/is waaay better. > and 250nF. Any amplifier incapable of dealing with those amounts of > capacitance (on the end of a speaker cable and crossover) does not > deserve to be called an audio amplifier. It is no better than a door-stop. ** So that would include all the Phase Linears and of course Naims. FYI: These amps lacked output Zobel inductors. FYI-2: Later piezos included 33ohm series resistors or tiny lamps that helped. BTW: I have done 4 cycle tone burst tests on various piezos and lemme tell ya the results are not pretty. .... Phil |
| jurb6006@gmail.com: May 06 02:41AM -0700 >"** So that would include all the Phase Linears and of course Naims. FYI: These amps lacked output Zobel inductors. FYI-2: Later piezos included 33ohm series resistors or tiny lamps that helped. " Then that would include my 400-2. However, I found a page a while back that said that coil there is not correctly referred to as a Zobel. It's not a big deal. Had a Sony reel to reel a long time ago, had speakers. I decided to hook it to my Peavey T-1210s. They had a bank of three peizo tweeters per, and all that thing did was hum, so of course I disconnected it. It was the bias oscillator leaking into the output. >"BTW: I have done 4 cycle tone burst tests on various piezos and lemme tell ya the results are not pretty. " Oh, I'll bet. The things are not known for real high fidelity, to say the least. Anything peizo is non-linear and if you need anything in audio, it is linear. I am surprised they got ceramic phono cartridges to work so well. In fact years (decades) ago I had a situation where I had a ceraic cartridge and a magnetic input on the amp. I shunted the cartridge with a resistor, I do not remember the value. It also seemed to take off the rolloff of the cartridge which normally would make RIAA EQ unecessesary. It actually sounded good going through an RIAA EQed preamp. It was an Astatic 353D IIRC. I don't remember what kind of amp, but back then I was in the amp of the week club. But a peizo tweeter, it almost only puts out noise. If you want to claim the response and have a hot high end, cross them over at at least 8KHz, which puts second harmonic at 16 KHz. Most people will never hear it. Use a horn for up to 8 KHz if you are looking for volume. And I do like the 33 ohm series resistor idea. |
| Phil Allison <pallison49@gmail.com>: May 06 05:12AM -0700 jurb...@gmail.com wrote: -------------------- > >"** So that would include all the Phase Linears and of course Naims. > FYI: These amps lacked output Zobel inductors. > FYI-2: Later piezos included 33ohm series resistors or tiny lamps that helped. " . > Then that would include my 400-2. ** Eeeeeeyeppp..... > However, I found a page a while back that said that coil there is > not correctly referred to as a Zobel. It's not a big deal. ** Which I did not. I used a longer. more specific title. > Oh, I'll bet. The things are not known for real high fidelity, > to say the least. Anything peizo is non-linear and if you need > anything in audio, it is linear. ** Tone bursts reveal the "timer domain" behaviour of a speaker. Good ones radiate the exact same number of cycles they are fed. Poor one radiate an extra cycle, or two. I found peizos were having a drunken party.... > And I do like the 33 ohm series resistor idea. ** Yep - it's pure genius... ..... Phil |
| Gunther Heiko Hagen <guntherxxx@quantserve.de>: May 05 11:46PM Hey, I got a bunch of stuff at a bankruptcy sale a few weeks ago. One of the items was a HP audio oscillator with an unknown (to me) type of mains socket. Heres a picture of one of the same type: https://upload.wikimedia.org/wikipedia/commons/8/8f/IEC60320_C14.jpg I don't recognise this. Can someone tell me what country it was intended for use in and what the likely required supply voltage would be? I'm guessing it's probably 110 or 240 but need to know for sure. Thanks. |
| Rheilly Phoull <rheilly@bigslong.com>: May 06 08:02AM +0800 On 6/5/17 7:46 am, Gunther Heiko Hagen wrote: > for use in and what the likely required supply voltage would be? I'm > guessing it's probably 110 or 240 but need to know for sure. > Thanks. Google iec 60320 It is in use in Australia 240vac |
| "tom" <tmiller11147@verizon.net>: May 05 09:02PM -0400 "Gunther Heiko Hagen" <guntherxxx@quantserve.de> wrote in message news:oej2rn$i5l$1@dont-email.me... > for use in and what the likely required supply voltage would be? I'm > guessing it's probably 110 or 240 but need to know for sure. > Thanks. Is the HP model number some secret or not? That connector is commonly called an IEC connector. It can be either 120 or 240 volts. If you let us know the model of the HP equipment, someone can most likely direct you to a PDF copy of the service manual with all the answers. |
| Phil Allison <pallison49@gmail.com>: May 05 06:11PM -0700 Gunther Heiko Hagen wrote: > https://upload.wikimedia.org/wikipedia/commons/8/8f/IEC60320_C14.jpg > I don't recognise this. ** You live at the North pole ?? That socket is used on every second electronic item sold. Been the case for 30 years too. ..... Phil |
| Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: May 06 01:41PM +1000 On 6/05/2017 9:46 AM, Gunther Heiko Hagen wrote: > for use in and what the likely required supply voltage would be? I'm > guessing it's probably 110 or 240 but need to know for sure. > Thanks. **This has to be a wind-up! It's a standard IEC mains connector. Same as that fitted to about 95% of all desk-top PCs, monitors, flat screen TV sets, audio equipment and test gear for several decades. They're in use all over the planet. -- Trevor Wilson www.rageaudio.com.au |
| tabbypurr@gmail.com: May 06 12:12AM -0700 On Saturday, 6 May 2017 00:49:18 UTC+1, Gunther Heiko Hagen wrote: > for use in and what the likely required supply voltage would be? I'm > guessing it's probably 110 or 240 but need to know for sure. > Thanks. That must be one of the 2 most popular connectors on the planet. There are probably billions in Europe. NT |
| Cursitor Doom <curd@notformail.com>: May 06 09:08AM On Fri, 05 May 2017 21:02:01 -0400, tom wrote: > If you let us know the model of the HP equipment, someone can most > likely direct you to a PDF copy of the service manual with all the > answers. Wouldn't help. These pieces of equipment are internally or externally switchable between 120 and 240V so you need to know what that switch has been set to. I think HP IIRC also used another scheme whereby you placed the appropriate fuse in the appropriate holder for the voltage of the country in question. So you would have two fuse holders, one for 120V and one for 240V and you placed your fuse - say for example 1A for 240V or 2A for 120V - in the appropriate fuse-holder. Have a look around the sides and bottom of the casing for any clues. |
| oldschool@tubes.com: May 05 02:19PM -0400 On Fri, 5 May 2017 17:06:22 +1000, Trevor Wilson >to stick to the 5532 though, as it can source more current than most OP >amps. One point: When you whack a new one in, check for DC offset and >oscillation. A remote possibility, but a real one. I am sticking with the 5532, but it will be a 5532P not 5532A. I cant locate the 5532A anywhere. Can you please explain what you mean and what I am supposed to do to perform this test for DC offset and oscillation...... >> I guess before I can do much more, I have to find a place to order a >> 5532A chip (or several of them so I have spares). >**They should be very easy to locate. I keep a dozen or so in stock. I have found many of the 5532P, but the 5532A is not showing up. I though the "P" was an upgrade, but from what I read, the TI (Texas Instruments) ones have the "P" suffix. I hope the "P" versions work as replacements. I ordered 20 of them from ebay for about $4.50. Thats surely cheap enough. They are TI brand. >> WHAT THE HECK DO YOU GUYS USE FOR PROBES ON THOSE TINY PINS? DO THEY >> SELL SPECIAL PROBES OR PROBE TIPS FOR THIS PURPOSE? >**Yep. They sure do. Could you provide a URL link so I know what to look for. I did do a search on ebay, Parts Express and Digikey. There are a million probes and tips. Some look more usable on chips, simply because they have thin pointy tips. One even had a coating on the whole tip except the very tip, but without having them in hand, I am not sure what will work best. So, a URL would help so I know what you and others use. There are lots of those ones that have a hook on the end, which you push the top and it opens. I have some of those, and they are handy to clip on the leads of a part, but are not real useful for chips. >> The good thing is that all the ICs in this device are plug in socket >> types. Thank God for that!!! >**Your job is then dead easy. As soon as I get my chips, I'll change that one that appears to be bad. The fact that it's running very hot pretty much tells me it's bad. I an not seeing any other bad parts around it, by doing a simple test with the device OFF and using the ohm scale on my VOM. I dont have anything to test chips, and I dont even know if they make such a thing, because every chip has a different pinout. Like I said before, I dont normally even tackle devices with IC Chips. But this circuit is simple enough I am, and confident I can fix it. What's nice about a preamp (or amp) is that I can just use my Paco and listen for sound. I started at the beginning and moved ahead till there was no sound (by this chip). I also worked backward from the output and determined that there was no sound anywhere after this chip. I only found that this chip was hot, when I was trying to move a cap so I could read the part number on the board, and when I touched that chip, I nearly burned my finger. Incidentally, this is the same chip that powers the LED VU meter. So it all ties together. I think what happened was this chip was failing. I had audio on both channels, but one was quieter than the other. (I am not sure which one it was though). I compensated by adjusting the volume accordingly. Then I lost the audio on that channel entirely. I assume that chip completely failed at that point (after I had it powered up for a few hours). That chip probably overheated and self destructed. Thanks for your help! |
| "Dave M" <dgminala@mediacombb.net>: May 05 08:40PM -0500 > Instruments) ones have the "P" suffix. I hope the "P" versions work as > replacements. I ordered 20 of them from ebay for about $4.50. Thats > surely cheap enough. They are TI brand. You're probably correct in your diagmosis that the 5532A is bad. It shouldn't be running hot at all - slightly warm, maybe, but not hot. I looked at datasheets from several manufacturers, and the only difference that I saw was that the "A" model has a gurarnteed input noise voltage specification, whereas the non-"A" model is not guraanteed, So, you'll be OK with your chips from Ebay. Cheers, Dave M |
| Phil Allison <pallison49@gmail.com>: May 05 08:33PM -0700 Trevor Wilson wrote: > amp. Nowadays, they're a dime a dozen. Still a decent OP a though. Well, > dual OP amp. For test purposes, you could try almost anything. Such as: > TL072, LF353, LM1458, LM833 (the closest equivalent to the 5532). ** Beware of the LM833, its is highly prone to oscillating at several MHz. More often than not, if used to replace the others mentioned above, the damn thing will have a steady oscillation at its output and much higher than normal THD in the audio range. ..... Phil |
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