Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Instruments and Amps Everything that makes music, Especially including instrument amps.

ohms and watts
ohms and watts
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 4th October 2005, 09:27 PM   #1
jud_fry is offline jud_fry  United States
diyAudio Member
Join Date: Oct 2005
Default ohms and watts

I'm still trying to find out how to go about putting together a cab with a head. If the cab is 600w and 8ohms, what is the minimum power i should look for in a head, and what is the maximum power i should look for in head, i don't want to overpower the speaker. I just don't know anything about this, and i can't seem to find any info anywhere. Thanks to anyone for some clarification, preferrably in layman's terms.
  Reply With Quote
Old 5th October 2005, 02:00 AM   #2
wes-ninja250 is offline wes-ninja250  Canada
diyAudio Member
wes-ninja250's Avatar
Join Date: Feb 2005
Location: Inverary, ON
Rule of thumb -- you're not nearly as likely to blow your speakers from an amplifier that is OVER powered as you are from one that is UNDER powered and driven into clipping. This may seem counter-intuitive, but it's true!

As for more specific numbers, somebody else will have to help.

Do daemons dream of electric sleep()?
  Reply With Quote
Old 11th October 2005, 02:30 AM   #3
guitargully is offline guitargully  United States
diyAudio Member
Join Date: Nov 2003
Location: Detriot, MI
Send a message via AIM to guitargully
600 watts is extremely high for guitar. i have a 40w tube combo and it sings like crazy.. marshall plexis are like 100 watts, and i've never heard of anything over 300 watts. An old half-stack i had had four 30 watt celections in it and the head was like 150 watts. i could crank it no problem.
say what? .. be careful with your ears.
  Reply With Quote
Old 11th October 2005, 08:40 PM   #4
Brett is offline Brett
diyAudio Member
Brett's Avatar
Join Date: Jan 2002
My housemate plays in a very loud metal band and uses a 100W tube head and doesn't put that near full volume most of the time.

100W is the max I'd recommend in a tube head for guitar, and 30-40W will likely be heaps. For a solidstate head, maybe 200W (max) as you usually don't want it to go into hard clipping because it sounds awful. With SS you'll need to get any distortion reqd from a pedal, tube preamp and the speakers overdriving/breaking up rather than the poweramp's contribution. May need a compressor pedal too, depending on what sound you're after.

Go and play as many amps as you can to get an idea what you need, as power and tone in guitar amps can be two entirely seperate things.
  Reply With Quote
Old 11th October 2005, 08:59 PM   #5
Byrd is offline Byrd  South Africa
diyAudio Member
Join Date: Dec 2003
Location: Cape Town, South Africa
Send a message via MSN to Byrd
Just a fact to note in terms of "Loudness" - 60 Watts into 8 (One tenth of 600 Watts) will be 1/2 the loudness of 600 Watts into 8

Or to put it another way - To double the loudness of an amplifier, you will need to increase wattage by a factor of 10.

Any wattage above 100 Watts "SHOULD" be fine - however the best way to make this decision is to remember the first fact mentioned (2 times loudness = 10 times power) while looking at prices of heads.

The more power the better as long as you get value for money in terms of loudness.

I wouldn't worry too much about clipping as usualy only tweeters are affected by this distoriton.
Ross Saunders
  Reply With Quote
Old 12th October 2005, 04:11 PM   #6
AndrewT is offline AndrewT  Scotland
Join Date: Jul 2004
Location: Scottish Borders
is a head something to do with a guitar amp?
Let's assume it is.
Guitar speakers are generally fairly efficient with an spl of between 95db/W and 100db/W.
At this level of output in an appropriately sized cabinets (for PA work) it is capable of 115db at 1m when driven at 100W. This is loud. It will completely drown out your voice.
The very big numbers of watts are more appropriate to wideband speakers that need big volts to drive low frequencies into speakers of much lower efficiency, often between 82db/W and 90db/W
I would tend to agree that smaller venues will work with 30W to 100W with a true PA speaker.
regards Andrew T.
  Reply With Quote


ohms and wattsHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
1500 Watts RMS - 2 Ohms, to come soon destroyer X Solid State 30 23rd March 2014 02:38 PM
382 watts into 8 ohms @ +-68 volts Samuel Jayaraj Solid State 14 11th August 2002 07:18 AM

New To Site? Need Help?

All times are GMT. The time now is 03:50 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio