Kevlar vs paper speaker cones

[fatecasino]

I am building a small battery powered 8' guitar amp 15W@8Ohm - 30W@4Ohm.
I am now to decide between 2 choices for speaker.
Celestion TF0818 94db 70h-6KHz 8Ohm Kevlar Cone
http://celestion.com/product/110/tf0818/

Celestion 8 15 95db 4Ohm 100Hz - 5KHz paper cone
http://celestion.com/product/8/eight_15/

I tend to prefer the TF0818 but I am a bit worried about the Kevlar cone. I know for sure that paper cone sounds best for guitars. What I mean "best" is hard to describe, but I simple mean it sounds as in any average commercial amp. Once I had bought a hifi polypropylene speaker for a small bass amp and the result was a catastrophe!

[Granny Gremlin]

Polyprop is smooth, and kevlar is textured.  I prefer kevlar but have only used it in hifi applications.  What I do know is that even with paper cones I prefer ribbed to smooth for guitar.  Polyprop definately won't give the same cone breakup that paper does.  Kevlar likely won't either unless very thin and push very hard; not sure.

[FiveseveN]

8" driver providing 94dB sensitivity and 100Wrms (AES standard) power handling

You're feeding it 15 W. Why are we worried about breakup?

[Granny Gremlin]

Not worried about breakup but rather quite the contrary;  mentioned it because it is often a desirable thing for a guitar speaker to do.

[fatecasino]

I also found this
http://www.fane-international.com/downloads/Fane%20Sovereign%208225%20DS030513.pdf
Nominal Chassis Diameter 8" / 203.2 mm
Impedance 8 Ω
Power Handling 225 w (A.E.S.)
Peak Power (6dB Crest Factor) 900 w (A.E.S.)
Usable Frequency Range -6dB 55 Hz - 5 kHz
Sensitivity (1 w - 1 m) 97 dB
Moving Mass inc. Air Load 20 grams
Minimum Impedance Zmin 7.6 Ω
Effective Piston Diameter 6.496" / 164.99 mm
Peak Displacement Volume of Cone Vd 0.085 litres
Magnetic Gap Depth 0.31" / 7.87 mm
Flux Density 1.0 Tesla
Coil Winding Height 0.59" / 14.98 mm
Voice Coil Diameter 2.0" / 50.8 mm
FS Hz 62 Hz
RE Ohms 6.1 Ω
Qms 4.3
Qes 0.42
Qts 0.38
Vas Ltr 22 litres
Vd litres 0.085 litres
CMS (mm/N) 0.34 mm/N
BL T/m 11 T/m
Mms (grms) 20.69 grams
Xmax (mm) 5.5 mm
Sd (cm2
) 213 cm2
Efficiency % 1.25%
Le (1k Hz) 1.47 mH

which is cheaper and it shows better characteristics that celestion TF0818

[blackieNYC]

The thing I'd be concerned most with is probably efficiency. A louder speaker, sort of, which will be nicer on your battery.

[fatecasino]

I am not an expert, but I think energy-wise I should search for a 4 Ohm speaker, but there are not plenty of them

[tca]

I've played with some Kevlar cones. They have a nice fat and textured punch that I like.

That  Fane Sovereign 8-225 deserves a try

Cheers.

P.S. (edit)

Here's a pic on a not so old build:

[PRR]

> battery powered

You want real EFFICENCY. "Sensitivity" is a guide, though not the same thing.

What you really want is AREA. All speakers are too small to get a good grip on the air. 2 Twelves should beat the snot out of any single Eight. 8 Tens will impress even with quite small amplifier power (thus battery drain). Yes, transportability enters into the compromise, and one Eight may be a good choice, but I'd look at Tens also.

Note there is a couple-pound difference in weight. If transportability is an issue, the extra arm-strain may matter.

Impedance has about no effect IF you can select the voltage to suit the impedance and power desired. Batteries are generally low voltage so low Z may be best. But you can also bridge two amps to get 4X the power at the same impedance and voltage. Car-sound chips are generally 15W-20W at 4 Ohms with 12V supply; this does suggest a 4 Ohm speaker, or two 8r jobs to increase cone area.

[Granny Gremlin]

. 2 Twelves should beat the snot out of any single Eight.

Obviously; I think you meant 2 8s will beat a 12.

[fatecasino]

You want real EFFICENCY. "Sensitivity" is a guide, though not the same thing.

What you really want is AREA. All speakers are too small to get a good grip on the air. 2 Twelves should beat the snot out of any single Eight. 8 Tens will impress even with quite small amplifier power (thus battery drain). Yes, transportability enters into the compromise, and one Eight may be a good choice, but I'd look at Tens also.

Note there is a couple-pound difference in weight. If transportability is an issue, the extra arm-strain may matter.

Impedance has about no effect IF you can select the voltage to suit the impedance and power desired. Batteries are generally low voltage so low Z may be best. But you can also bridge two amps to get 4X the power at the same impedance and voltage. Car-sound chips are generally 15W-20W at 4 Ohms with 12V supply; this does suggest a 4 Ohm speaker, or two 8r jobs to increase cone area.

Talking about amps is definitely difiicult as too many parameters are getting involved: purpose, amp chip, energy, cabin, speaker, etc.
I have done some previous attempts with battery powered amps before and everytime I try to go a step further. My last time, indeed I used a 12' Vox 30watt speaker with tiny giant and the result was truly awesome! The battery could play for 3-4 hours which good time for busking. Unfortunately every time you have to pay some money to make experiments, especially with speakers. The previous was a bit too big, that's why I want to build something smaller now with an 8'.
Through fora here I chose this D-class amp chip which really cheap and good quality:
http://www.dx.com/p/y148-audio-amplifier-module-93121#.VvVDY2F95cY

But you can also bridge two amps to get 4X the power at the same impedance and voltage.

I have tried many times to understand how bridging amps works but in the end I couldn't get it. If you can send me some advice on how to do it with this amp, please send me some schematic.

Now,
about choosing speaker for this amp.
1. The Celestion 8 15 is cheaper, it's for sure good for guitar, 4 Ohms, sensitivity 95db but only 15W rms, I am afraid it wont manage to take the whole volume of the amp
2. The celestion TF0818 is much more expensive (but I found it really cheap in Thomann), 8 Ohms, 95db, but I am afraid of the kevlar cone if it's gonna give my guitar this terrible hifi sound
3. The Fane Sovereign 8-225, is same price ~50€m, 8 Ohms, 97db (!), I don't know if it's good for el. guitar or if I have to crossover it with a tweeter.[/li][/list]

What do you think?1,2 or 3?
thanks
[/list]

[amptramp]

I would prefer Kevlar over paper just for the extra strength and waterproofing you can get.  You should never rely on speaker breakup; that is what you are supposed to be using stompboxes for.  You want the best efficiency you can get.  Note that Kevlar is not like the polypropylene speaker you used - it is not a film structure, it is more like fibreglass in that you have woven Kevlar with a polyester coating.

[PRR]

> bridging amps ... how to do it with this amp

That amp is already bridged.

Anyway, it has 10W-20W at 12V; how much power do you need? You do not want to over-power, that just eats battery when not playing flat-out. (D-amps are better in the aspect.)

Two Eights is at-best comparable to one Twelve. Usually not even that good. For real electric-acoustic efficiency, you want More Area. Of course for best busking efficiency you need a rig you can carry.

[fatecasino]

> bridging amps ... how to do it with this amp

That amp is already bridged.

Anyway, it has 10W-20W at 12V; how much power do you need? You do not want to over-power, that just eats battery when not playing flat-out. (D-amps are better in the aspect.)

Two Eights is at-best comparable to one Twelve. Usually not even that good. For real electric-acoustic efficiency, you want More Area. Of course for best busking efficiency you need a rig you can carry.

I read in other fora that this amp is already bridged, but once in an stereo amp I would like to make it happen; just to realize the difference. How do I get the maximum wattage out of this amp? The information I found are a bit confusing for my understanding. It's already bridged, there are 2-3 things though that have to be soldered additionally, but I cannot figure out which ones exactly. I wouldn't like to destroy such a nice small amp

[PRR]

> How do I get the maximum wattage out of this amp?

Use 15 Volts and two 4 Ohm loads.

That's 60 Watts output, more than most club-amps; and will drain a battery very fast.