Speaker Wattage

[a1terrier]

Hi again. Just about finished my first cab. Pleased with result. Cant do any more until kit arrives in a few weeks. Kit is 5 watts. What wattage speaker would be best. As you can tell I am a novice when it comes to valve amps so sorry for all the questions but I am learning a lot from all your replies. Thanks.

[hasserl]

Your main concern should not be wattage, but voicing. Different speakers produce different sounds. Two basic categories are British & American, their are several versions of both (Celestion, Jensen, JBL, Weber, Eminence, Ware House, etc); and then there is magnet type: alnico, ceramic and now neodymium, each one effects the sound (& weight) in slightly different ways.

What you probably need to do is tell us what kind of amp your building and the size of speaker, and how much room you have in the cabinet, and then people can offer up their personal (subjective) preferences for that style of amp and size of speaker. After that wattage is a simple matter, if there are options in wattage available for the type of speaker you can just go with the lowest power rating.

[stingray_65]

to confuse you even more

guitar amps and the like don't use HiFi speakers. They use musical instrument speakers.

if you hook a MI speaker up to your stereo i'tll sound like mud! but boy oh boy hooked up to a tube amp and they sound amazing!

you see an amps speaker is the final ingrediant into the "TONE" equation.
first is the instrument itself and the cable.
second is the amp
third the speaker.
all of these have HUGE influences as to what the over all sound will be and changing any one of those ingrediants can give you drastic changes.

HiFi speakers on the other hand are designed NOT to flavor the tone of music. they re-create the music that has been made.

get it?

so like HASSREL suggested.. what flavor are you looking for?

[a1terrier]

Many Thanks for replies. Tone? Probably after the `Ultimate Strat Sound` whatever that is!! Seriously though something akin to Messrs Knopfler, Marvin, Gilmour. Love playing clean Am Std Strat, your advice is much appreciated, but as you say the speaker is only one part of the equation. As this is my first valve amp build I dont want to spoil it by buying unsuitable speakers etc. The owner of the amp kit place suggested a Celestion G12, which are not too bad on price, so may take his advice. Thanks again.

[stingray_65]

LOL well what's the kit?

Share your journey we want to hear about it and cheer you on!

[a1terrier]

Kit is from Ampmaker in the UK (www.ampmaker.com) £140 with some very good online instructions. He only does a 5 watt and an 18 watt at the moment, so as its my first valve build I`ve gone for the 5 watt (Its only for home and occaisional jam with friends) Gets some good reviews on Harmony. As I said he suggests a G12H speaker so may go with that. Must admit that cab making is addictive. Managed to beg 3/4" plywood from a customer, so hasnt really cost me anything yet apart from my time. Will keep you posted on progress later as cant order kit until April as he is so busy. Cheers

[hasserl]

Seeing as the kit is described as having a British tone I think the Celestion suggestion is probably a very good one, especially since the suggestion comes from the kit builder.

Nice looking website/kit BTW. Good luck with it and have fun!

[stingray_65]

HAHAHA!
some one caught the bug
anyone who claims any kind of work is addictive or could be has already been bitten.

it looks to have Marshall topograghy and will likely have that classic "British" sound so a Celestion or Celestion copy would harmonize nicely

simple tube or valve amps like yours lend themselves to endless modifications to change thier sounds, quite a bit like changing pickups , strings and volume and tone controls in a guitar.

You're going to be amazed the first few times you play your amp if especially if you never played a tube amp before, what i find humorous is when my son's metal head buddies suddenly want to play on his little 15 watt amp and make comments about how the amp sounds better than thier such and such effect pedal

it will only get better and smoother too the more you use it, the speaker will break in and the tubes will take a set. a month of playing and you'll hear richness warmth and depth that you've never heard before.

keep us posted on your progress and post pics if you can.

we'd all love to see your cab too, lots of fine craftsmen here can help you hone your skills.

[a1terrier]

Thanks for replies and encouragement. Im presuming that at 5 watts I can crank it if I want to without blowing the patio doors off!! Will post pic of cab as soon as possible. Afraid its not fingerjoints as I dont have the tooling, so its butt joints screwed glued and dowelled and its bang on 90 degrees at every corner! Not bad for a first attempt.

[a1terrier]

Pics attached ( hope!). Done a lot of sanding/finishing since these were taken

Amp Cab 001.jpg

[guitician]

Looking at your "Fender'ish" cab, and that you want an "Ultimate" Strat tone, I would suggest finding a late '50's early 60's Jensen P12R. An old alnico with a very "tight" cone and very "light" voice coil have such amazing dynamics the guitar just links up with the speaker and they become one sonically.

Oh, one other thing, old radio speakers can work very well driven with a low wattage amp. I used to find them at flea markets, and was surprised at thier tone.

[a1terrier]

Thanks for that Guitician. Think the kit will take 8 ohm or 16 ohm. Whats the
one to get??

[olddawg]

Originally Posted by guitician

Looking at your "Fender'ish" cab, and that you want an "Ultimate" Strat tone, I would suggest finding a late '50's early 60's Jensen P12R. An old alnico with a very "tight" cone and very "light" voice coil have such amazing dynamics the guitar just links up with the speaker and they become one sonically.

Oh, one other thing, old radio speakers can work very well driven with a low wattage amp. I used to find them at flea markets, and was surprised at thier tone.

In the old days there wasn't as much a distintion between Hi Fi , PA and MI speakers. The guitar amp companies just used what was available and least expensive. I got a pair of 12" CTS square magnet speakers out of an old console stereo a while back that were identical to what I have seen in major brand guitar amps of the same era. It was going to the dump. eBay has quashed a lot of cheap stuff that used to be everywhere but you can still find jems at garage sales and thrift stores if you have the time especially in large equipment. Modern stereo speakers have foam surrounds and are totally inadequate for MI applications, but most paper surround speakers out of old stereos, etc will work fine as long as you are sane about pushing them.

[guitician]

Originally Posted by a1terrier

Thanks for that Guitician. Think the kit will take 8 ohm or 16 ohm. Whats the
one to get??

8 or 16 ohms it doesn't matter. Just match the output transformer to the speakers ohms. If you dont know the speakers ohms, meter the DC resistance and it will usually be close to 4, 8 or 16 ohms on the low end. Like a 4 ohm speaker coil will measure 2 to 3 ohms, or 8 will measure 6 to 7 ohms, etc.

[pdf64]

'Im presuming that at 5 watts I can crank it if I want to without blowing the patio doors off!'
Not a safe assumption. 5 watts clean will be nearly 10 watts when cranked, into a 100dB/W speaker = ~110dB, which will have the ornaments dancing off the shelves at least.
100dB/W means that 1 watt will create 100dB soundpressure level at 1 metre, therefore
2 watts will be 103dB, 4 watts 106dB, 8 watts 109dB. Add 3dB every time power in is doubled.
If you want to be loud (ie keep up with a drummer) you need an efficient speaker (100dB/W ie G12H30), whereas if you want a cranked tone at more domestic friendly levels (jamming with a buddy), you need a lower efficiency speaker, say a Jensen P12R at 94 dB/W. Peter.

[stingray_65]

great point OLDAWG
I do a lot of recycling of vintage parts and I know first hand what you say is true.

I just got the feeling when our newcommer asked how many watts , that he was going to find something as big as the hole and what ever anyone said to be the power capabilities and he would just put it in .

UGG! could you imagine if he found one of those bass speaker the kids put in thier cars!
I realy would like to see him enjoy his first tube amp
so i emphasized an MI speaker.

the beauty of vintage speakers when you can find them in good order is that the cones already have a mellow set to them and you get the results of a break in imediatly.

[stingray_65]

BTW
cab looks great!

what are your plans for the covering?

I 've recently covered an amp in denim , fresh material , not old blue jeans like the pics on that site.

its just a tiny 2 watt, but its my sons practice amp and my GOD he treats it like a tonka truck and so far its just as durable

I have to honestly say is it the most forgiving material i have ever used.

and with all the varieties available i'll use it again.

[a1terrier]

Interesting reply re `Old` speakers. I have a pair of 30 year old 12" Wharfedale speakers in the garage. In good condition, Ive looked but cant seem to see the ohm on them,

As regards covering Im probably going to use good old Tolex in conservative black. Ive put some half round beading on the front edges which makes the cab look good. Need to find a good Tolex tutorial somewhere, although if I get stuck (?) one of my customers at at work is a top upholsterer so he will help me out if I give him a free box of staples!

[a1terrier]

Thanks for info on speaker Peter. Much appreciated. This is a very steep learning curve for me but a very enjoyable one.

[olddawg]

Originally Posted by a1terrier

Interesting reply re `Old` speakers. I have a pair of 30 year old 12" Wharfedale speakers in the garage. In good condition, Ive looked but cant seem to see the ohm on them,

As regards covering Im probably going to use good old Tolex in conservative black. Ive put some half round beading on the front edges which makes the cab look good. Need to find a good Tolex tutorial somewhere, although if I get stuck (?) one of my customers at at work is a top upholsterer so he will help me out if I give him a free box of staples!

In general a speaker coil's DC resistance will measure out at slightly lower than the rated impedence. An 8 ohm speaker will read around 7.2 ohms, a 16 ohm around 15 ohms, and a 4 ohm around 3.2 ohms with a good digital meter with decent leads. Hook those babies up. You never know.

Here's a tutorial:
http://steelguitarforum.com/Forum11/HTML/008611.html

You might also look at:
http://www.18watt.com/

Or one of the many other amp building sites. If you use contact cement just make sure that you do it in a HIGHLY ventilated area away from any flames or sparks, including funky fan motors.

[a1terrier]

Found the spec it was inside the speaker cab.
9 1/2" diameter
Nom Imp 6 ohms
Frq Respose 50hz to 20 khz + or - 3db
Max Power 40 watts
Sensitivity 86 db for 1 watt @ 1 metre
xover points 1.3 khz & 4.5 knz
xover rates 6db 12 db per octave
Manufactured by Rank Wharfedale.
As I said they must be 30 years old just cant bear to throw them away even if they are no good for my cab.

[olddawg]

Originally Posted by a1terrier

Found the spec it was inside the speaker cab.
9 1/2" diameter
Nom Imp 6 ohms
Frq Respose 50hz to 20 khz + or - 3db
Max Power 40 watts
Sensitivity 86 db for 1 watt @ 1 metre
xover points 1.3 khz & 4.5 knz
xover rates 6db 12 db per octave
Manufactured by Rank Wharfedale.
As I said they must be 30 years old just cant bear to throw them away even if they are no good for my cab.

From looking at the specs I would say this is for the whole cab. It includes the crossover specifications. I would guess that it has a mid range driver and a tweeter. If they are mounted separately in the cabinet and the woofers have paper surrounds they may usable as 10" MI speakers. If the midranges and tweeters are mounted coaxially on the woofers they probably aren't. Then again I have sucessfully removed the additional coxail drivers from other speakers and used them in amps in a pinch. A pic would help. Most stereo woofers had foam surrounds by 30 years ago (1979) and would not be usable as MI speakers.

[a1terrier]

Thanks for reply Olddawg. Have attached 4 pics. Speaker is rubber mounted onto a steel frame. As I said if they are no use as an amp speaker, fine. I`ll probably clean them up and use them for bbq music etc.

[guitician]

A rubber surround woofer will not have any midrange and the midrange speaker will not have any low midrange punch like a guitar speaker. I have seen acoustic amps with speakers like that in them, for a more "Hi-Fi" sound that and acoustic amp would need.

[olddawg]

Originally Posted by a1terrier

Thanks for reply Olddawg. Have attached 4 pics. Speaker is rubber mounted onto a steel frame. As I said if they are no use as an amp speaker, fine. I`ll probably clean them up and use them for bbq music etc.

Yeah, those are stereo speakers not suitable for guitar. However, if nothing is blown they appear to be very decent 3 way stereo speakers. The fact that it has a good dome tweeter and a midrage driver is a good indicator. I took a similar set of speakers and built them into the wall of my living room low down on both sides of a 52" LCD TV hanging on the wall. I did it because my wife complains about big stereo speakers in the room, so I built everything into the wall.

[stingray_65]

you know what i'm thinking?

now that you got the tube amp bug and all

you need a tube hifi system

a couple 12ax7's a nice pair of se OT and who knows maybe some 7868 to give it a Fisher kind of sound

[a1terrier]

Thanks again for replies. Looks like Celestion G12 here I come. Pity because when I bought the Wharfedales back in the late 70`s they were pretty expensive as I remember. Thanks for suggestion re valve hi-fi but might have to pass on that one. Divorces quite expensive these days! Got to convince the wife that I really need another amp yet. Shes seen the cab, asked what its for so I told her and not heard another comment about it so might have got away with it!!
Might make a head now so that cab is just for speaker.