Ekko 4/15/2018 5:35 AM
Best tweeter/small speaker for my purpose?
Hi -- I'll be getting a Fender Rumble V3 100 bass combo. The basic sound is great for my baritone acoustic guitar, which is strung with 6-string-bass strings and tuned down to a low G. It has a 12 inch speaker, but no tweeter (the bigger Rumbles have compression tweeters). The top end might benefit from adding a tweeter or a small diameter speaker. I want to avoid anything that might be harsh sounding -- something really smooth that perhaps only went up to 16k. Cost wise, up to about Ģ50/$75. I'd be grateful for any advice.
 
J M Fahey 4/15/2018 8:19 AM
The Faital Pro Italian made speakers are incredibly good and reach high frequencies *without* the typical horn harshness (let alone Piezo harshness) because besides being incredibly well made, they use very light aluminum wire voice coils, while equivalent Eminence use heavier copper wound. 1) unless you find a closed ("blind") basket one, youīll need to close its back if mounted in the same cabinet as the woofer (no problem if you mount 1 or more in a separate enclosure) so bass pressure does not push/suck the poor little cone all over the place. You may kludge a small wooden box out of some plywood or even glue a stiff cardboard tube from the inside, covering its end with a round (or square, nobody will see it anyway) piece of plywood. Drill a small hole to let wires through and seal it with hot glue or similar so mini speaker chamber is separated from the main one. 2) you will need a highpass crossover so only high mids and highs reach the mid/tweeter. Not endorsing anybody, but US Speaker has both, browse their catalog: [url=http://www.usspeaker.com/faital%20pro-3fe25-1.htm]Faital Pro 3FE25 3" Speakers - Faital Pro 3FE25 mid-high speaker. The Faital Pro 3FE25 has a wide frequency range from 100Hz to 20kHz and has a ferrite magnet. Faital Pro 3FE25 40 watt 3" has an efficiency of 91dB SPL for all high quality mid-high ap[/url] [url=http://www.usspeaker.com/faital%20pro-4fe35-1.htm]Faital Pro 4FE35 4" Speakers - Faital Pro 4FE35 mid-high speaker. The Faital Pro 4FE35 has a wide frequency range from 90Hz to 20kHz and has a ferrite magnet - Faital Pro 4FE35 60 watt 3" has an efficiency of 91dB SPL for all high quality mid-high ap[/url] Small World indeed. I love ultra defined Bass , but hate Piezo harshness, so , since I make my own speakers, just cooked a batch of 100 4" mid/high speakers, very much with the Faital formula ... only I used straight paper edges (no need for lower frequencies) and closed back frames, for ease of mounting: [ATTACH=CONFIG]48471[/ATTACH] [ATTACH=CONFIG]48472[/ATTACH] [ATTACH=CONFIG]48473[/ATTACH] oh, the dustcap is still unattached; I always let speakers "rest" a couple days until adhesives really set. After stamping/pressing/turning the 100 speakers (minimum batch because itīs all "metallurgical" work, not "electronic") I almost fainted when my cone supplier told me "[I] 4" tweeter cones? NOBODY uses them any more so we have none left . You want us to import a few for you? No problem, 5000 units is the minimum order, paid for in advance[/I]" :thumbsdown: I asked them to check their records for the last customer who bought them, they luckily found a guy still stocking 1000 or 2000 of them (in cheesy white colour only) , unused gathering dust on a shelf, so he saved my life.
 
tedmich 4/15/2018 11:16 AM
JMF definitely knows his stuff on this, Faital (and B&C) are some of the best Italian speakers. Of course you'll need a crossover and possibly an attenuation circuit (fixed L-pad or variable L-pad) in order to "dial in" this new driver. There's probably not a lot of signal above 1k Hz coming out of the Rumble so a 50W rating on these is probably fine. I'd probably add a 2nd order highpass at 1-2 kHz, with terminals flipped (to get phase right) and try out a cheap variable L-pad. If you like it full on, I'd remove the L-pad (they are noisy and age poorly) or reproduce any "magic setting" with fixed resistors. Let us Know how it works out! The bigger Rumbles compression tweeter (yuck!) is available on Ebay... One reason people use these is because the crazy efficiency of big pro audio speakers, sometimes you need 105 db/W on a little mid/tweeter just to keep up!
 
Ekko 4/16/2018 1:13 AM
Many thanks! -- will respond in more detail this evening.
 
Ekko 4/16/2018 10:28 AM
Hi JMF -- thanks for your very detailed, interesting, and helpful reply! The tweeters on ebay mentioned by Tedmich (thanks) used in the bigger Rumbles are rated at 40 watts RMS. Should I make sure that the speaker I buy is at least that wattage?
 
J M Fahey 4/16/2018 5:58 PM
Not sure, power rating in Tweters is a complex issue. * [B]Actual[/B] power handling at the Tweeter voice coil usually is from 5 to 10W RMS , maybe 15W RMS tops, those voice coils are *tiny* and must be very light in order to reproduce treble well, above what a regular speaker does. But nobody ever connects a tweeter straight to the amplifier, they always use a crossover ... at least a small value capacitor (think 2.2 / 4.7 / 10 uF film or bipolar electrolytic), so they only get the highs included in the program. So usually "[I]40W RMS Tweeter[/I]" actually means "[I]5W RMS Tweeter which thanks to the crossover can be used with a 40W amplifier ... since it will never get more than 4 or 5 W RMS by itself[/I]". * Piezo tweeter ratings are even murkier: they do NOT have a copper wire voice coil at all, but they "are" a ceramic capacitor which twists and flexes under applied voltage. No thermal dissipation (ok, there is[I] a little[/I] of it, since material was optimized for mechanical movement, not usual capacitor duty) but they may and do crack with excessive voltage applied. A common rating is 35V which is about what a 150W amp can put out, so they are often rated "150W RMS" ... while label [I]should[/I] read "[I]usable with an amp of [B]up to[/B] 150W into 8 ohms[/I]" . Oh well. Please link to those "EBay tweeters" to have a look at them. FWIW my own which I pictured above can take honest 15W RMS .... which is A LOT. Almost forgot: most Tweeters are used with a series resistor for attenuation, since many times they are more efficient than matching woofer. Now if you have an 8 ohm tweeter and put an 8 ohm resistor in series (a common combination), this combo now is 16 ohm equivalent and tweeter by itself gets 1/4 the power sent to it (since the resistor eats half the voltage) ... so "[I]official power rating is quadrupled[/I]" In hard driven Musical Instrument and PA cabinets itīs common to put a car lamp bulb in series with tweeter, so it acts as an "automatic resistor" to protect it. Look at this "400W" crossover: [url=http://www.usspeaker.com/px-b1k6-1.htm]Eminence pxb-1k6. The Eminence pxb-1k6 is a 1600Hz high pass crossover. The Eminence pxb-1k6 1.6kHz high pass crossover handles 400 watts RMS.[/url] it woud be perfect for you, only itīs somewhat expensive and over rated, get a cheap 2000 or 2500 Hz general purpose crossover and add the car lamp yourself (usually a 12V 15W one).
 
Ekko 4/17/2018 3:40 PM
Thanks Juan -- and here is the link:

https://www.ebay.co.uk/itm/Fender-Ru...item2120aa9b30
 
J M Fahey 4/17/2018 4:28 PM
Ok, I checked my small stash of Rumble schematics and all use the Piezo horn, with a 47 ohm resistor in series, period and as expected, *except* the "500" which shows a dynamic (magnet + voice coil) Tweeter.

They make it VERY simple: plain 1uF cap in series with an 8 ohm 5W resistor ... as simple as can be .

Since your EBay tweeter claims to be that one, then use that simple cheap Fender blessed crossover

[ATTACH=CONFIG]48521[/ATTACH]

Small detail: I am often shunned when I speak about: Tweeter/drivers actually handling very low power *at the voicecoil*" ... you can feed a lot to the crossover, but little reaches the tweeter itself.

But as you can see this one has a 5W 8 ohm resistor in series ... meaning Tweeter voice coil does not expect more than that (being in series and same impedance both always dissipate the same).

EDIT: for sake of completeness and easy comparison hereīs the standard Piezo tweeter layout:
[ATTACH=CONFIG]48522[/ATTACH]
 
Ekko 4/18/2018 1:09 PM
Okay, I'll go with the Ebay tweeter and that simple crossover -- thanks for taking the time to advise me so fully!
 
Ekko 4/18/2018 3:09 PM
Wasn't expecting this: I've just taken a look and there is not enough room to fit the tweeter in! The only thing I can now think of
would be to replace the 12" speaker with a lightweight coaxial speaker.
 
Ekko 4/18/2018 3:13 PM
Wasn't expecting this: I've just taken a look and there is not enough room to fit the tweeter in! The only thing I
can think of now would be to replace the 12" speaker with a coaxial speaker.
 
Ekko 4/18/2018 3:34 PM
Then again, I guess I could try to find an equivalent tweeter with a slightly smaller surround.