Amplifier Modification

[chibi]

I got a Behringer 15watt practice amp which i've ripped open and replaced the speark and the entire box to my own liking.. proplem is that it's still only rated to power up to 15 watts so i can;t get a full punch out of my speakers... Would anyone know if theres a way i can crank up the power on my amp to say 100watts or greater. honestly my goal is to make up a 200watt setup so i can power four 10 to 12 inch speakers to make a cabinet set up.

looking for suggestions...

[Southpa]

Sure, go buy an amp thats got 100W + potential, rip out the guts and shoehorn into your little 15W Behringer. There is no recipe to soup up a 15 watter to 100+Watts without frying some components and/or blowing speakers.

[marksound]

You realize that a 200W head will not be appreciably louder than, say, a 50W head through the same cabinet, right?

[sepultura999]

You realize that a 200W head will not be appreciably louder than, say, a 50W head through the same cabinet, right?

Marksound is right. A 200 watt head will sound double as loud as a 20 watt head. It's not like if one's 20 and the other is 40, then therefore it's double.

15 watt amps can be pretty loud. There is a website out there where a guy sells a 1 watt amp because he claims a 1 watt amp is more then enough. I own a fender deville 4x10 and that's way too loud. The reason why I got it is because it was going cheaper on ebay then the Deluxe was new in stores, used in classifieds and at the time for some odd reason there was none on ebay (weird lol). You may just want to fork the money out to get a peavey classic or fender blues junior, or learn how to build your own. AX84 is a site which offers blueprints and material lists to build a small tube amp that will be loud enough.

-Jamie

[chibi]

the reason why i said 200watt was because i have four 50watt speakers i can use.. so i wanted something that can atleast power them all evenly.. but with in a budget.

[Samba Pa Ti]

afaik the behringer 50watt amp can power (2) 4 speaker cabs (left and right) without any trouble and will sound very loud, also as a comparison the beatles (and alot of other people) used/use vox ac30's which are 34 watt amps, and they are deafening past 5 on the volume.

on another note isnt the 50watts mentioned (speakers) their max output ? going over 50 or even getting near it will damage the speakers and cause them to blow (especially if they are old), the speakers in my amp(2 of) are rated to 110watts yet the amp is only 60watts to both channels (left/right).

correct me if im wrong here. :D

Edited February 11, 2006 by Samba Pa Ti

[chibi]

these are brand new speakers, and my behringer is a 15watt... i just want to know if theres someway to modify the amp to be able to power four 50 watt speakers, let alone i said 200watt was my goal, it was more of wishful thinking but something i can try to work towards.

[Samba Pa Ti]

this is the only way you can get that setup to work with a decent output. making a cab with the speakers then running everything through it (mic/bass/guitar)

http://img488.imageshack.us/img488/774/untitled6mb.jpg

Edited February 11, 2006 by Samba Pa Ti

[chibi]

what if i took the output signal from the amp and plugged it into a stereo amplifier? if the stereo amplifier had the power do u think it be safe from any problems?

[Samba Pa Ti]

it would work but the hifi wouldnt last long the Europower box is basically a amp just alot more powerfull. i wouldnt recommend it.

http://www.behringer.com/EP1500/index.cfm?lang=ENG

edit

it would be a hell of a lot cheaper to get a bigger amp i went from a 10watt to a 60watt and i cant turn it past 3 volume, and also it would be very gig-able

Edited February 11, 2006 by Samba Pa Ti

[chibi]

true...

this is just for fun though. So i guess myonly option is to buy a bigger amp.

hmmm... what if i built one from scratch? know of any schematics i can get online?

[Samba Pa Ti]

theres more out there just a few i picked up whilst nosing around.

http://www.runoffgroove.com/articles.html

http://www.fortunecity.com/tinpan/humperdinck/223/newp2.htm

http://blueguitar.org/schems.htm#Amps

http://www.diyguitarist.com/

[jnewman]

I'm sorry, but I have to chime in here. I'm really not trying to be either rude or mean, but I have to say this. If you felt like it was reasonable to ask if you could mod a 15W amp to 100W or 200W, you have no business (at this point) building or modifying anything with tubes. Vacuum tube amps run with some potentials over 350V DC which can and will kill you if you do the wrong thing.

If you want to learn more about electronics and learn (and get to be in the habit of) safe building practices and then start on tubes, go ahead - but jumping in without any background is very, very dangerous.

Edited February 11, 2006 by jnewman

[lovekraft]

If you felt like it was reasonable to ask if you could mod a 15W amp to 100W or 200W, you have no business (at this point) building or modifying anything with tubes.

+1!!

A 1 watt amp will drive a standard Marshall cabinet (1960A/B) hard enough to get a good sound out of it - if it doesn't sound good, power (or the lack thereof) is not your problem. If it isn't loud enough, get a bigger amp or more efficient speakers. Amp mods are great, but they'll never make a 15 watt practice amp into a 100 watt hi-gain head. There ain't no such thing as a free lunch.

[Samba Pa Ti]

I'm sorry, but I have to chime in here. I'm really not trying to be either rude or mean, but I have to say this. If you felt like it was reasonable to ask if you could mod a 15W amp to 100W or 200W, you have no business (at this point) building or modifying anything with tubes. Vacuum tube amps run with some potentials over 350V DC which can and will kill you if you do the wrong thing.

If you want to learn more about electronics and learn (and get to be in the habit of) safe building practices and then start on tubes, go ahead - but jumping in without any background is very, very dangerous.

aye thats a good point its ok to go and do a cheap "mod" or build a amp for peanuts but safety is more important.

it does say on the back of most amps not to remove the cover as no parts are servicable, (for obvious reasons).

[Paul Marossy]

A 1 watt amp will drive a standard Marshall cabinet (1960A/B) hard enough to get a good sound out of it - if it doesn't sound good, power (or the lack thereof) is not your problem.

Yep. Watch the Z. Vex Nano Head video. He's driving a 4x12 cab with a little 1 watt mini-amp, and it sounds pretty loud to me.

http://zvexamps.com/amp_view.html

[chibi]

well i fully understand there can be a risk and the idea of modifing my amp is slighlty out there... i was just looking for what you guys would of thought about it. But yea.. give me as much input as u can.

thanks for your opinions

[lovekraft]

Don't wanna sound harsh, but you're pretty much in the "jack it up and run a better one up underneath it" zone - there are a few inexpensive low power tube amps that make great mod platforms, but unfortunately, Behringer doesn't make one. If you're serious about building one, spend some time over at AX84, and you'll get the scoop on what amp building is about, but keep in mind that it ain't easy, and it's definitely not cheap!

[sepultura999]

There's even some people out there who won't waste time building amps, but would rather just mod it like you, and I hear one of the best buys for modding is a Pignose tube amp, since they go for like 250-300 bucks

[gripper]

I did some reccomended mods to a Epiphone Valve Junior and the results were dramatic. It will now quietly (no humm) drive my Marshall 4/12 cab nuts with a ART preamp in front of it. $142.00 and about $20.00 in parts. Not a bad deal for 15 screaming watts. Valve Jrs ROCK!

[Daniel Sorbera]

I deffinitly wouldn't touch a tube amp if I we're you. But on the wattage issue. This was taken from the FAQ section of AX84.com (great website)

The way that watts translate into decibels is in powers of 10. That being the case, if you want to do twice as loud, you need to go 10x higher in wattage. The difference in volume between 100W and 50W is actually only 12% less or so. HALF the volume of 100W is actually 10 watts, and TWICE the volume of 100w is actually 1,000 Watts. And when is the last time you played a 100W amp on a setting higher then 3 on the volume without everyone screaming to turn it down!

Now, after you have digested that, we can move along to the next part.

Speaker efficiency is also key to volume. That curve is also not linear. If you take 2 otherwise identical speakers, one with a sensitivity rating of 103dB, and one with a rating of 100dB, that -3dB drop is the equivalent of sending half the power into the speakers... like moving from a 100W amp to a 50W amp, of about a 12% drop in power.

Now, if you move from the 103dB speaker to a 97dB speaker that is otherwise identical, that -6dB drop is like moving from a 100W amp to a 25W amp. That being the case, a 25W amp played through 103dB speakers is exactly as loud as a 100W amp being played through 97dB speakers.

OK, digest that for a second and then we'll move on.

Last week, I played a 35W amp on full blast (but not clipping) through a Marshall 4x12" cabinet loaded with Celestion Vintage 30's, which have a sensitivity of 100dB. I took out a sound pressure level meter and put it 10 feet away from the speakers. The 35W amp produced a clean power level of 117dB, which is only 3dB quieter than an airplane landing.

With all that in mind, you should decide on whether you really want to go with the added expense, weight, maintenance and extra wiring that a 100w amp requires.

-Aletheian-Alex

A 15watt amp running through four very efficent speakers (103db or so) will be loud enough to blow your ears out. If you play in venues that need more than that your going to be running through the house PA anyway so whats the big deal?

Edited February 12, 2006 by Godin SD

[Samba Pa Ti]

aye thats so true those little 8 inch speakers dont do the amp justice...

[Paul Marossy]

If you are considering building a tube amp, the beginner projects at AX84 are all good ones. There is also one that I built that is called "Octal Fatness", and it's a GREAT sounding little single-ended amp that puts out about 5-7 watts depending on what power tube you use. I also built the Firefly, which is about 1/2 to 3/4 watts using a self-split 12AU7 as the driver tube. It gets pretty loud for such low wattage. And it's now an official AX84 project, too.

Here's my Octal Fatness page: http://www.diyguitarist.com/GuitarAmps/OctalFatness.htm

And my Firefly page: http://www.diyguitarist.com/GuitarAmps/FireFly.htm

[chibi]

hmm... wish i was a part supplier so i can goto town on that one right now. to bad this isnt a perfect world, oh well.

[BigG1986]

to shift this over slighty from vavles what fwould you do to increase the volume out of a solidstate line 6 spider amp with 100w - 2-12' 8ohm tubetone speakers with LM3886TF amp chip finals????