Guitar power amplifier MOSFET SE 5W - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

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

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
Reply
 
Thread Tools Search this Thread
Old 16th January 2015, 03:47 PM   #1
diyAudio Member
 
Join Date: Jan 2008
Default Guitar power amplifier MOSFET SE 5W

Hi,

this is modified ACA amp from Nelson Pass for use as guitar power amplifier. It sounds great.

Enjoy.
Attached Images
File Type: png ACA 5W SE MOSFET Guitar.png (16.2 KB, 119 views)
  Reply With Quote
Old 19th January 2015, 02:39 PM   #2
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Nice to see someone try this out! Was discussing this possibility on another thread, any demos /pictures of it that you could post? What speaker are you using?
Cheers
  Reply With Quote
Old 19th January 2015, 03:19 PM   #3
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
Hi ,
very nice work , I like it! post any pictures?'
It would be better to use a much smaller cap than 47,000 uF on yer power input. That large value is useful for 50-60 Hz unregulated linear PS! the PS using a laptop replacement SMPS is operating at > 40,000 Hz AND is most probably regulated (good) Too large values can indeed upset the negative feedback loop inside a SMPS (bad). For best results try values in the 100's uF range designed for SMPS. use a common mode choke to clean up stray PS hash once you attached O-scopes and see some signals.
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote
Old 19th January 2015, 03:29 PM   #4
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
It's 4700 uF on the schem, which would be pretty good, yes?
  Reply With Quote
Old 19th January 2015, 03:32 PM   #5
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
Quote:
Originally Posted by shanx View Post
It's 4700 uF on the schem, which would be pretty good, yes?
ah yes an extra zero in there,
get rid of 1 more .

Quote:
try values in the 100's uF range designed for SMPS
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote
Old 19th January 2015, 03:48 PM   #6
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
I was expecting to see a replacement MOSFET fitted into an old practice amp holding B+ at 160 V.
This one is Hi-Fi
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote
Old 19th January 2015, 07:31 PM   #7
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by shanx View Post
Nice to see someone try this out! Was discussing this possibility on another thread, any demos /pictures of it that you could post? What speaker are you using?
Cheers
I am using 1x12 Celestion V30 speaker 8 Ohm. You can find pictures of ACA amp in this thread: Amp Camp Amp - ACA
  Reply With Quote
Old 19th January 2015, 07:37 PM   #8
diyAudio Member
 
Join Date: Jan 2008
Here is the original article of ACA amplifer by Nelson Pass:

Amp Camp Amp #1

Mind you, that there is bias mod for ACA which makes the idle current 1.5A. In the original article the mod is not included, so measurements are little worse with 1A bias.

You can use different power mosfets than IRFP240. I havenīt tried any others, but it could be interesting to use some with lower capacitances (and gm also).

It sounds better than DIY build of class A EL34 guitar amplifier (Hi-Octane by AX84).

For preamp I recommend you AMT Legend amps series (JFET preamps).

Anyway design is very simple and I donīt think there is more to tweak or change.
  Reply With Quote
Old 19th January 2015, 07:41 PM   #9
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Hi Kacernator,
Nice speaker that. Yes am aware of ACA, just wondered if you built using the PCB or did own setup. Did you mount it in the ACA style enclosure, or musical amp style enclosure?
  Reply With Quote
Old 19th January 2015, 07:54 PM   #10
shanx is offline shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Apparently the 1.5 A bias mod will lower the distortion somewhat, which for guitar amp purpose may not even be as ''desirable''?... Another tweak would be to run with reduced NFB or possibly adjustable (100K range)? Accordingly to Mr. Pass design, he has come up with another amp that is simple and stable even without feedback. I've got some of the parts, but not the PCB or time to build yet.
Just having you comparing the ACA with a AX84 High Octane makes me want to fire up the soldering iron! Better you say.. that should be quite good!
Cheers
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
ACA as 5W guitar power amp kacernator Pass Labs 5 17th January 2015 08:15 AM
5w SE guitar Amp N9VOC Instruments and Amps 16 18th August 2010 06:34 PM
op-amp based mosfet power amplifier for guitar rig Dusk Instruments and Amps 30 27th September 2006 10:23 PM
mosfet power amplifier for guitar Dusk Solid State 0 30th July 2003 02:39 AM


New To Site? Need Help?

All times are GMT. The time now is 06:04 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright Đ1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2