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

Pass Labs This forum is dedicated to Pass Labs discussion.

Medium Aleph 3 8ohm@20w.
Medium Aleph 3 8ohm@20w.
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 24th February 2018, 05:00 PM   #1
Nag is offline Nag  India
diyAudio Member
 
Join Date: Dec 2015
Default Medium Aleph 3 8ohm@20w.

Hi All,
I am looking for 8ohm@20W amplifier.

1. My speakers are rated at 8ohm@20W. But ALEPH3 has 8ohm@30W.
2. ALEPH3 has 200W power dissipation. My required 8ohm@20W can lower power dissipation to 160W.
3. ALEPH3 has bias 1A in each output stage. And matching is required for parallel output.
I can lower components and can increase bias to 1.5A so it will reduce distortion and improve sound quality.
4. I removed protection circuit as it not required.
5. lowered zener diode series resistance as suggested by NP.
6. I replaced MPSA18 with ZTX450 as MPSA18 not available.
7. INPUT IRF9610 replaced by FQP3P20 as suggested(Toshiba but not available) by NP.
It is a mini -aleph with modifications suggested by NP.
I don't have experience in choosing R11 resistor value so I copied from another ALEPH circuit.
So please suggest if any modification is required to achieve above.
It is a mini aleph with modifications suggested by NP.
Thanks,
Nag.
Attached Images
File Type: png aleph20watt.png (41.4 KB, 1020 views)
  Reply With Quote
Old 24th February 2018, 05:27 PM   #2
Zen Mod is offline Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Medium Aleph 3 8ohm@20w.
with 15Vac secondaries , there will be around 18Vdc at rails

with Iq 1A ....... dissipation will be 36W per channel

resulting power will be around 15W/8R , with rails as limiting factor

just make regular Aleph 30 , with just one pair of outputs

18Vac secondaries , resulting in 22V5dc rails

set Iq to your liking , say 1A for starters ...... then up until you hit what you want - either desired dissipation or temp of 50C at heatsinks or max dissipation of some 40W per mosfet

post Aleph 30 schematic here ....... that amalgam you made is ...... wrong in enough places
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 24th February 2018, 06:42 PM   #3
mpmarino is offline mpmarino  United States
diyAudio Member
 
mpmarino's Avatar
 
Join Date: Jun 2004
Location: Northeast USA.
Don't be afraid to wander from the IRFP240.

It might be worthwhile to use IRFP140 or 150 - this way you'll worry a bit less about the current thru just one pair.
__________________
Crazy Yankee.
  Reply With Quote
Old 24th February 2018, 07:09 PM   #4
Zen Mod is offline Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Medium Aleph 3 8ohm@20w.
yup

that's why I put IRF150 in Babelfish J

proven up to 50W per piece , with proper heatsinking arrangement
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 25th February 2018, 08:58 AM   #5
Nag is offline Nag  India
diyAudio Member
 
Join Date: Dec 2015
Hi,
Is this ok ?. It is same circuit ALEPH 3 with only one output modifications suggested by NP.
I this circuit provides 2A to speaker it it asks.
Attached Images
File Type: png aleph3revised.png (41.6 KB, 958 views)
  Reply With Quote
Old 25th February 2018, 12:09 PM   #6
Zen Mod is offline Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Medium Aleph 3 8ohm@20w.
now :
- change R108 to 270R and add trimpot of 500R in series
- change R113 to 39K , add 100K trimpot in series

make these changes , then put connecting dots on all connecting points and post it , just that we are sure that you're getting it all

you need just two 0R47 resistors in output rail , so remove 2 of them
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 25th February 2018, 04:27 PM   #7
Nag is offline Nag  India
diyAudio Member
 
Join Date: Dec 2015
Dear Zen_Mod,
Thanks for your valuable time. Here is the latest schematic diagram.
Thanks,
Nag.
Attached Images
File Type: png aleph3revised2.png (64.2 KB, 907 views)
  Reply With Quote
Old 25th February 2018, 05:18 PM   #8
Zen Mod is offline Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Medium Aleph 3 8ohm@20w.
nicely done

now - if you want some leeway , regarding Iq and dissipation ..... and few more freebies - use IRFP150 instead of IRFP240 , and you're done

150 is practically two of 240 in one case
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 25th February 2018, 08:46 PM   #9
chede is offline chede  Germany
... fascinated by amps
diyAudio Member
 
chede's Avatar
 
Join Date: Jan 2016
Location: In the Düsseldorf suburbs
Medium Aleph 3 8ohm@20w.
I actually did a similar thing (built on BrianGT boards): started out as Aleph Mini, but morphed into an "Aleph10" or "Aleph Single" or whatyawannacallit ...
It is an Aleph30 with a single set of outputs. I used IRFP140s with source resistors of 0.22 Ohms (and sense resistors with a resulting resistance of 0.11 Ohms).
Run with either +/- 19V rails at 2.2A bias, or +/- 24V rails at 2.0A bias.
Both worked very well. No stability or drift problems. I preferred the sound of the 19V / 2.2A version, but have speakers that are a very easy load.

Also excellent suggestions by Zen Mod to add the trimmers - that will allow you to easily adjust bias and offset.

Best regards,
Claas
  Reply With Quote
Old 26th February 2018, 07:22 AM   #10
Nag is offline Nag  India
diyAudio Member
 
Join Date: Dec 2015
Hope Infineon and Vishay IRFP150 100V 41 Amp N-Channel MOSFET both are same.
We have local availability of Vishay IRFP150 100V 41 Amp N-Channel MOSFET.
Attached Images
File Type: png aleph3revised2.png (66.5 KB, 807 views)
  Reply With Quote

Reply


Medium Aleph 3 8ohm@20w.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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
63watt class A into 8Ohm, 110watt semi-class A into 8Ohm, @ 20Khz 3rd harmonic -90dB FdW Solid State 47 31st December 2010 04:05 PM
8ohm resistor in series with 8ohm speakers for a 16ohm OT? Reidy- Tubes / Valves 8 10th January 2010 11:25 PM
Large Cone/large VC or several medium sized cones / medium VCs vajolet Multi-Way 14 3rd December 2007 06:10 PM
Aleph-2 50W@8ohm 20KHz emb51 Pass Labs 8 8th September 2006 04:10 PM


New To Site? Need Help?

All times are GMT. The time now is 09:40 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki