ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.	New: view Recent Searches. New: visit Schematic Hell! The sunn still shines online!

Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

power attenuator schematics?

4/8/2003 3:43 PM
josh camp	power attenuator schematics? Does anyone know where I can get info / schematics on how to build a power attenuator like a hotplate or airbrake?

4/8/2003 3:55 PM
BWilliamson	This interests me as well, but alas I'm too dumb. Weber has a interesting product I keep eyeing in the Mass unit. But I'd also like to try to build one, he has a simplified schem on his site: http://www.webervst.com/mass.gif Kinda surprised a bunch of ampagers haven't run with this and came up with something yet. I'd buy his product but I don't need the DI output and would like to play with a couple of the options. bwilliamson boxerboards.com

4/8/2003 3:55 PM

BWilliamson
email

This interests me as well, but alas I'm too dumb.

Weber has a interesting product I keep eyeing in the Mass unit. But I'd also like to try to build one, he has a simplified schem on his site:

http://www.webervst.com/mass.gif

Kinda surprised a bunch of ampagers haven't run with this and came up with something yet. I'd buy his product but I don't need the DI output and would like to play with a couple of the options.

bwilliamson
boxerboards.com

Tuesday

Book Of The Day

The Ultimate Tone, Volume III by Kevin O'Connor

Have you ever wondered if there is a better way to build a Bassman, Champ, Plexi, an 800, AC-30, Bulldog or Portaflex? Or you wanted to build an SVT with off-the-shelf parts? How about a master-volume amp that doesn’t change tone with the master setting? Everything you need to know is right here, including: proper grounding techniques, wiring methods, and mechanical considerations. Eighteen chapters cover the “iconic” amps everyone knows and loves, with schematics and layouts for each, along with the technical history of the product. Eyelet-board and chassis-mounted tube socket construction is used throughout, for easy servicing and modding. TUT3 is very accessible even if you cannot fully read a schematic and is a "must have" if you are going to build an amp for your self.

Note: The Ampage Archive is an Amazon Associate site. A small commission is paid to the site owner on any qualified purchase made after clicking an associate link such as the one above.

4/9/2003 11:47 AM
pef	Here: http://www.lalena.com/audio/calculator/lpad/help.shtml http://www.lalena.com/audio/calculator/lpad/

4/9/2003 12:28 PM
Todd Hepler	Spend some time here : http://www.aikenamps.com/spkrload.html and here : http://www.blueguitar.org/new/schem/marshall/powerbrk.zip RE weber mass attenuators - There are several folks here that have these. -T

4/9/2003 7:40 PM
pef	Hey Todd, sorry but the first link is not a attenuator but a speaker load simulator...

4/9/2003 9:14 PM
Todd Hepler	Hey pef - I think with a few additions this would make a great load box - A quote from Randall's article : If you want to add a line out feature for recording, tap off the input of the circuit; that is, at the junction of the amplifier output and R1. Use a resistive divider to lower the signal level (make sure the divider resistance is much larger than the output or load impedance) The idea is that a reactive element approximates the impedance curve of a speaker much better than a resistive voltage divider.-Weber's MASS applies this concept literally by using a speaker's motor assembly to duplicate the reactive elements of a speaker/cab combo- Some of the resistive attenuator users have complained of the tone sucking capabilities of the units at higher attenuation settings. A couple more resistive designs from Blue Guitar : http://www.blueguitar.org/new/schem/misc_mod/power_sk.jpg http://www.blueguitar.org/new/schem/misc_mod/volreduc.gif -T

4/9/2003 9:14 PM

Todd Hepler

Hey pef -

I think with a few additions this would make a great load box -

A quote from Randall's article :

If you want to add a line out feature for recording, tap off the input of the circuit; that is, at the junction of the amplifier output and R1. Use a resistive divider to lower the signal level (make sure the divider resistance is much larger than the output or load impedance)

The idea is that a reactive element approximates the impedance curve of a speaker much better than a resistive voltage divider.-Weber's MASS applies this concept literally by using a speaker's motor assembly to duplicate the reactive elements of a speaker/cab combo- Some of the resistive attenuator users have complained of the tone sucking capabilities of the units at higher attenuation settings.

A couple more resistive designs from Blue Guitar :
http://www.blueguitar.org/new/schem/misc_mod/power_sk.jpg

http://www.blueguitar.org/new/schem/misc_mod/volreduc.gif

-T

4/11/2003 7:04 PM
bob predaina	i would avoid the recommendations about L-pads and T-pads. one thing that you may want to consider is looking in a basic electronics textbook under the subject heading "Ladder Attenuators." These are devices that are specifically designed for attenuating the output of a device while maintaining the impedance seen by the devices at the driving end and receiving end of the circuit -- exactly what we want for a guitar amp application. IIRC the old Handbook for Radio Engineers had a good section on this topic. the airbrake and similar products may not be as good a solution to the problem as a ladder attenuator. the airbrake type of design uses a simple approach with a pair of resistors, a rheostat, a cap, and a 2-deck rotary switch. imho a real ladder attenuator would be a better option than any of the commercial options out there, but it would be a bit more expensive to build.

4/11/2003 7:04 PM

bob predaina

i would avoid the recommendations about L-pads and T-pads.

one thing that you may want to consider is looking in a basic electronics textbook under the subject heading "Ladder Attenuators." These are devices that are specifically designed for attenuating the output of a device while maintaining the impedance seen by the devices at the driving end and receiving end of the circuit -- exactly what we want for a guitar amp application. IIRC the old Handbook for Radio Engineers had a good section on this topic.

the airbrake and similar products may not be as good a solution to the problem as a ladder attenuator. the airbrake type of design uses a simple approach with a pair of resistors, a rheostat, a cap, and a 2-deck rotary switch. imho a real ladder attenuator would be a better option than any of the commercial options out there, but it would be a bit more expensive to build.

Page 1 of 1