Bullet tweeter vs piezo

[drstringlove]

Provided Link: http://www.partsexpress.com/pe/pshow...264-822http://


Just receive my order from PE with a new bullet driver to replace an obselete piezo in a friends bass amp. The link with the new drivers specs. is below. I'm wondering if I need to add some extra parts (capacitor?) to protect the new tweeter? What value? Anyone got an idea\answer for me?

[envisionelec]

> Just receive my order from PE with a new
> bullet driver to replace an obselete piezo
> in a friends bass amp. The link with the new
> drivers specs. is below. I'm wondering if I
> need to add some extra parts (capacitor?) to
> protect the new tweeter? What value? Anyone
> got an idea\answer for me?

Please tell me you linked the wrong tweeter. This is a "low power" Home audio tweeter.

[drstringlove]

> Please tell me you linked the wrong tweeter.
> This is a "low power" Home audio
> tweeter.

I can't imagine what you'd say about the one I took out. The new one weighs twice as much. The new tweeter is rated at 80 watts RMS and, I really didn't think this little combo bass amp was more than 100 watts total anyway. BTW, just noticed on the schematic that the tweeter is paralled with the woofer but the tweeter receives its power through a 4mf cap. Will this be ok as is? Thanks.

[envisionelec]

> I can't imagine what you'd say about the one
> I took out. The new one weighs twice as
> much. The new tweeter is rated at 80 watts
> RMS and, I really didn't think this little
> combo bass amp was more than 100 watts total
> anyway. BTW, just noticed on the schematic
> that the tweeter is paralled with the woofer
> but the tweeter receives its power through a
> 4mf cap. Will this be ok as is? Thanks.

Wow, you're kidding me.

Tweeter weight does not equal power handling. The 4uF cap will work, but I think you're gonna blow this tweeter on the first slap.

[nick29498141]

That baby is a home-dome, it will behave very differently from a bullet tweet.

NK

[drstringlove]

> That baby is a home-dome, it will behave
> very differently from a bullet tweet.

> NK
OK so maybe it'll be a well traveled "home dome" if it survives, I really didn't want to modify the cabinet, and it was one of two that I found that would actually fit in the 2.5" hole. The other one costs $2 and change. Please don't tell me I'd be better off with the $2 one. It looks like the headphone output is padded with a 10watt resistor from the speaker output, if that tells you anything. The original was all plastic except for the copper coil.

[shawn_a]

The tweeter you chose will have a very hard time keeping up with the other drivers in the cab. BTW, what is the driver compliment anyway? 4x10? 2x10? 15? 18?

shawn

[drstringlove]

SWR Bassic Black, one 15" sorta looks like an EV frame I remember from the past, two little bitty power transistors, amp about 13 yrs old, the amp is for stage, but the direct out goes to the house, so the tweeter doesn't even effect what is heard off the stage. I wouldn't even have put one back in, but my friend asked me to.

[matg]

get a piezo, rasp out the hole if you need to, it will take more abuse than the dome you selected. that's my 2 cents

> Just receive my order from PE with a new
> bullet driver to replace an obselete piezo
> in a friends bass amp. The link with the new
> drivers specs. is below. I'm wondering if I
> need to add some extra parts (capacitor?) to
> protect the new tweeter? What value? Anyone
> got an idea\answer for me?

[shawn_a]

I had an SWR Workingman combo back in the day. Damn I loved that piece. Almost as much as my Warwick bass.

Enough of the groveling from me. Just slap another piezo back in place of the old one. If I remember correctly, the Basic Black was replaced with the Black Beauty and that had a piezo tweeter with a 3 1/2" square faceplate or thereabouts. If that's the case, try these on for size.

<A HREF="http://www.partsexpress.com/pe/showd...number=272-100">http://www.partsexpress.com/pe/showd...number=272-100</A>

You get a pair for the price so if one dies, you friend will have a spare. Or look for a comparable horn tweeter. The original tweeter was crossed at around 5kHz IIRC. Hope this helps.

shawn

[drstringlove]

....you're telling me this 75 watt piezo is superior to a tweeter rated at 80 watts.

[shawn_a]

Ever wonder why you don't see soft dome tweeters used in MI cabinets? It's because they generally aren't physically tough enough for the general abuse the gear sees and they just don't have the sensitivity to keep up with a pro sound woofer or mid.

Look at the sensitivity of the tweeter you bought. Hmmm, 90 dB. Now look at the cheesy Pyle piezos I linked to which are at 94 dB. A four decibel difference is nothing to sneeze at and the 94 dB is most definitely closer to the sensitivity of the 15" woofer. The TangBand would be a whisper to that 15's scream. At least with the piezo it would have a fighting chance at longevity and actually being heard.

SWR builds nice stuff and they even manage to do it using piezo tweeters. A new Black Beauty will put you back around a thousand bucks these days. There is considerably more money put into the woofer than the tweeter. I still say go with the piezo.

shawn

[Some Guy]

Provided Link: Partes Express Resource Index


> I can't imagine what you'd say about the one
> I took out. The new one weighs twice as
> much.

Piezos work on a different principle than dynamic voice coil driven drivers.

> The new tweeter is rated at 80 watts
> RMS

Well, not really. You put 80 watts through that tweet for more than a few milliseconds, tens of milliseconds at best, and watch it turn into an expensive fast blow fuse.

> BTW, just noticed on the schematic
> that the tweeter is paralled with the woofer
> but the tweeter receives its power through a
> 4mf cap. Will this be ok as is? Thanks.

With a 4 ufd cap I might try adding a coil, say 0.2 to 0.4 mH, in parallel with the tweeter inputs to make this thing at least a seond order 12/db filter, provide some damping and work to shunt some of the more potentially damaging low frequencies.

I'm not going to join the club that says this tweet will die on the first slap because frankly I don't know that there is all that much energy above 5KHz from a bass -- Len Moskowitz successfully used a "hi-fi" 2 inch horn loaded dome mid from Peerless that was crossed over at around 1KHz in his compact bass cabinet -- and 5KHz is not too awful far from where you're crossing (with a way too shallow first order slope) using a 4 ufd cap on this tweet. Spend a buck or two for a coil and it might last a little longer.

As far as the "obsolete" piezo in your initial post, piezos do have their uses (which is why they've been around so long) and their ability to work with cheap, cheap crossovers made of nothing more than a series resistor and capacitor and go on playing day after day is one of the principle reasons for their continued use.

I'll be interested to know how long this little TangBand tweet lasts...but do at least add a coil.

Check the PE Resource Index page (see link and also links at the top of the forum) for some info on piezo tweets and also on basic crossover design. But do add that coil.

[Some Guy]

> ....you're telling me this 75 watt piezo is
> superior to a tweeter rated at 80 watts.

Yes, you are missing something. Piezo tweeters are fundamentally different in the principle of operation than dynamic voice coil driver tweeters. Piezo elements are seen by the amp as essentially a "lossy capacitor" and dissipate very little applied voltage as heat. In other words they are very efficent high impedance low current devices and aren't prone to self destruction from overheating. Tiny little dynamic drivers like your TangBand have a very fine wire voice coil that doesn't much like the application of high power for any length of time and responds to such abuse by heating up (dynamic drivers are low impedance, low efficency, high current devices) and acting like a fuse.

The "power ratings" on hi-fi dynamic tweeters are best thought of as "system power" ratings when the tweeter is used in a hi-fi system playing back music with a more or less normal distribution of energy through the audio band.

Piezo tweets get used in things like guitar cabinets and cheap PA's because they're rugged devices that stand up very well in that environment. There is a reason you don't see commercial cabs using hi-fi dome tweets.

Anyway, like I posted before, add a 0.25-0.4 mh coil in parallel with this tweet (after the 4 ufd cap) to make a 12db second order filter and it might last a little longer than it otherwise would with just a simgle 4ufd series cap.

[drstringlove]

> Ever wonder why you don't see soft dome
> tweeters used in MI cabinets? It's because
> they generally aren't physically tough
> enough for the general abuse the gear sees
> and they just don't have the sensitivity to
> keep up with a pro sound woofer or mid.

Please don't think I'm not listening, I am, and as far as durability goes, I agree with you. Soundwise, frankly, I don,t care too much in this case if that tweeter is balanced with the woofer or not just as long as it stays working. In fact I am actually considering trying a 2 ohm 10 watt resistor in series with the tweeter, just to make sure it stays working.

> Look at the sensitivity of the tweeter you
> bought. Hmmm, 90 dB. Now look at the cheesy
> Pyle piezos I linked to which are at 94 dB.
> A four decibel difference is nothing to
> sneeze at and the 94 dB is most definitely
> closer to the sensitivity of the 15"
> woofer. The TangBand would be a whisper to
> that 15's scream. At least with the piezo it
> would have a fighting chance at longevity
> and actually being heard.

As I said above,

> SWR builds nice stuff and they even manage
> to do it using piezo tweeters. A new Black
> Beauty will put you back around a thousand
> bucks these days. There is considerably more
> money put into the woofer than the tweeter.
> I still say go with the piezo.

This amp, with no cable ties to stop vibration, had a wire break that was tied to ground, apparently caused a voltage spike, and took out two diodes. I did the surgery on the amp, having to remove an electrolytic cap that straddled a few other parts including the two diodes. Three out of four of the power supply caps were mounted on the board, and this one which BTW didn't match in value the other three, looked like they had forgot to leave a place on the circuit board for it. Several hours were spent on diagnosis and installing the two diodes. Now, it's working again and my friend says he wants a new tweeter. Well, *$^# the old tweeter hasn't worked for the last two years anyway. I advised him to look for another amp and eventually sell this one, I'm just not that impressed with it. In fact, he may just be worried about the resale without a working tweeter. Disturbing the ozite covering and RASPING out larger holes seems like a bit more than I want to bite off and chew. In other words, If it don't fit through the hole, I'm not putting it in. Overall, I think you'd agree that modifying stock cabinet features is not the best idea. Your piezo looks fine I just don't think it'll fit in the little bitty hole where the 2" piezo came out.

> shawn

[drstringlove]

[jimhunt]

> ....you're telling me this 75 watt piezo is
> superior to a tweeter rated at 80 watts.

what is the sensitivity on the piezo? looking at the sensitivity on that TB tweet, it won't match the woofer in that SWR amp very well. first time it gets turned up loud and the player really digs in........well how do you like your eggs because the tweet is cooked too!

[shawn_a]

If you still have it, measure the faceplate of the original tweeter or take a pic of it and post it or e-mail it to me. I just want to know what the stock piece looks like and get a feel for what will fit properly.

shawn

[drstringlove]

Especially Someguy, I'll probably dig around and see if I have a suitable coil in my stash. I can't see putting too much effort into this on an amp manufactured with a power supply cap straddling several other componets.

[drstringlove]

Square tweeter face measures 2 3/8" Round rear extension is 2" in diameter, Black plastic with captivating silver paint on the front. Lense is made to look like a bullet. Le son made in Brazil. Don't know what the power rating or original impedance was, but impedance now is about 5.5 ohms and the driver passes no sound.