AKAI AM 76 increase of damping factors - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 13th July 2007, 03:23 PM   #1
Goetz is offline Goetz  Germany
diyAudio Member
 
Join Date: Jul 2007
Default AKAI AM 76 increase of damping factors

Dear friends,

I want to increase the damping factor (only 40 !) of my Akai AM 76 integrated amplifier.
The caps have currently only 2x10.000mF,63V. This is the reason for the low damping and nonacceptable soft bass.
I'am not an electronic freak.
Is it simply possible to replace the two caps by f.e. 2x47.000mF or do I have to change more of the environment ?
Best regards
Goetz
__________________
Goetz
  Reply With Quote
Old 13th July 2007, 04:33 PM   #2
Goetz is offline Goetz  Germany
diyAudio Member
 
Join Date: Jul 2007
Default Correction AKAI AM 67 not 76 !

Sorry for my mistake: It is an AKAI AM 67 not 76 !
__________________
Goetz
  Reply With Quote
Old 13th July 2007, 05:27 PM   #3
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
The reason for the soft bass may or may not be the damping factor. 40 is not bad anyway. Not that increasing the DF is easy - you have to increase open loop gain or the number of output devices. A non starter if you are not an "electronic freak"

Increasing the PS capacitance will have no effect on DF although it may increase the perceived bass.

Akai amps are not well known for their great sound quality. Why don't you consider building something new?
  Reply With Quote
Old 14th July 2007, 08:10 AM   #4
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
Try adding a pair of 47F at 63V (or higher) in parallel with the main filter caps. The bass will sound much tighter.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 16th July 2007, 03:37 PM   #5
Goetz is offline Goetz  Germany
diyAudio Member
 
Join Date: Jul 2007
Default Re: Correction AKAI AM 67 not 76 !

Quote:
Originally posted by Goetz
Dear friends,

I want to increase the damping factor (only 40 !) of my Akai AM 76 integrated amplifier.
The caps have currently only 2x10.000mF,63V. This is the reason for the low damping and nonacceptable soft bass.
I'am not an electronic freak.
Is it simply possible to replace the two caps by f.e. 2x47.000mF or do I have to change more of the environment ?
Best regards
Goetz

Quote:
Originally posted by Goetz
Sorry for my mistake: It is an AKAI AM 67 not 76 !

Quote:
Originally posted by analog_sa
The reason for the soft bass may or may not be the damping factor. 40 is not bad anyway. Not that increasing the DF is easy - you have to increase open loop gain or the number of output devices. A non starter if you are not an "electronic freak"

Increasing the PS capacitance will have no effect on DF although it may increase the perceived bass.

Akai amps are not well known for their great sound quality. Why don't you consider building something new?

Quote:
Originally posted by djk
Try adding a pair of 47F at 63V (or higher) in parallel with the main filter caps. The bass will sound much tighter.
Dear Analog SA,

thanks for your advice. However the AKAI shall be the first modded Amp.
As next and may be new I'am looking for class A amp with at least 12 Watts . have you any proposals ?
Have a nice week
Goetz
__________________
Goetz
  Reply With Quote
Old 16th July 2007, 03:37 PM   #6
Goetz is offline Goetz  Germany
diyAudio Member
 
Join Date: Jul 2007
Dear DJK,

thank you for your advice. With which other amps did you practised such parallel capacitors ?
Best regards

Goetz
__________________
Goetz
  Reply With Quote
Old 16th July 2007, 05:06 PM   #7
ilimzn is offline ilimzn  Croatia
diyAudio Member
 
Join Date: Feb 2005
Location: Zagreb
Default Re: AKAI AM 76 increase of damping factors

Quote:
Originally posted by Goetz
Dear friends,
I want to increase the damping factor (only 40 !) of my Akai AM 76 integrated amplifier.
The caps have currently only 2x10.000mF,63V. This is the reason for the low damping and nonacceptable soft bass. I'am not an electronic freak.
Is it simply possible to replace the two caps by f.e. 2x47.000mF or do I have to change more of the environment ?
Best regards
Goetz
I am afraid you are making a number of asumptions which can at best be described as loosely founded in fact - which is surprising to me since you, by your own admission, are not an 'electronics freak'.

First off, damping factor may or may not have much with the percieved bass. For instance, tube amps have a relatively low damping factor, which on some speakers leads to overly boomy and loud bass. So, increasing the DF of the AKAI amp may (assuming you managed to do it) actually produce an oposite effect than the one you are looking for.

Second, the filter caps have very little to do with DF if anything. In fact, they may even have relatively little to do with the bass extension in general - there are many variables at play. Having had the pleasure of owning, and tweaking somewhat, an AM-67, if memory serves me right, the caps are a relatively low 10000uF Elna Audio caps, with very low ESR. This low ESR, together with the needed power reserve, help in power delivery, often very large caps are used because ESR tends to be lower with increase in capacity for a given type cap (which is reflected in a higher ripple current rating), and of course, the energy reserve FOR PEAKS is increased. But those are not the only variables - the power transformer is one large one, as well as a number of other, at first glance, minor things. If I recall correctly, the AKAI has a decently sized power transformer. There was a recomendation to add smaller caps in parallel with the main filter ones. This tweak does not increase power reserve, but decreases ESR at higher frequencies, where it may be predominantly inductive. Some amp topologies are prone to distortion injection and recycling through power rails. This often gives them a 'high pitched' sound with an apparent lack of bass. In fact, bass tends to be fine in such cases, it is the midrange that 'jumps ahead' with various harmonics of bass frequencies which should not be there. The good thing about this tweak is that it is unlikely to make things worse (even though in some cases even that can happen, but I will nto go into these speciffics here).
Regarding your question about replacing teh filters with larger capacity ones, in most cases you can safely try up to 1.5x the nominal capacity. Going any further requires good knowledge of the power supply circuit and transformer specs. It may or may not be possible - and as I said, it may not even be desirable.

Thirdly, increasing the DF on the AKAI may be done by some fraction by replacing the output switching relays and internal cabling, as well as speaker binding posts. In order to increase the DF of the amplifier circuit itself, one would have to understand how and why it is made the way it is, in GREAT detail. That being said, the particular AKAI amp is not of typical construction. If memory serves, it is a symetrical single ended current feedback amp joined into a push-pull topology, with P and N JFETs at the input. It is a rather complicated circuit of very high speed. I would strongly discourage you from poking around it at your level of knowledge.

Finally, this amp is a number of years old. It may well pay to do a selective re-capping. For this i strongly recomend a service manual. A look into the schematic (or sharing it here) may help in establishing the crytical caps to change. Old caps are most often the culprit for 'dry' bass, although if i remember the AKAI well, it was full of ELNA for Audio caps.
  Reply With Quote
Old 16th July 2007, 06:48 PM   #8
Goetz is offline Goetz  Germany
diyAudio Member
 
Join Date: Jul 2007
Dear Ilimzn,
thanky ou for your detailed advices. Your memory serves you well. There are 2x 10.000mf.
After ~ 12-15 Years of operation (I bought it used) may be all the caps in Audio line should be changed.
I'am lookig for the electronic plan. may be I will find a source.
To avoid misunderstanding. The level of bas is OK but too fat, it should be dryer or more precise.
best regards
Goetz
__________________
Goetz
  Reply With Quote
Old 23rd September 2008, 03:51 PM   #9
jaya000 is offline jaya000  India
diyAudio Member
 
Join Date: Dec 2006
Quote:
Originally posted by djk
Try adding a pair of 47F at 63V (or higher) in parallel with the main filter caps. The bass will sound much tighter.
Is it possible to get tight bass in any amplifier by adding two 47uF capacitors?
Any other idea to get more tighter bass?
  Reply With Quote
Old 23rd September 2008, 04:11 PM   #10
ilimzn is offline ilimzn  Croatia
diyAudio Member
 
Join Date: Feb 2005
Location: Zagreb
Quote:
Originally posted by jaya000


Is it possible to get tight bass in any amplifier by adding two 47uF capacitors?
Any other idea to get more tighter bass?
In general terms, no - there are so many different amp types it is impossible to say for sure what parallel caps will do, but based on general rules of electrical component behaviour, it is more likely they will affect treble.

Still, there may be places where a few 47uF caps can improve bass. Like for isnatnce the DC decoupling cap in a feedback loop for SOME amps (again, there are several ways of doing things)...
  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
Factors affecting speaker precision? keantoken Multi-Way 27 2nd September 2010 07:34 PM
OPT Quality Factors? weinstro Tubes / Valves 1 3rd November 2007 07:20 AM
Limiting Factors for high-frequency extension Nappylady Multi-Way 9 10th May 2005 06:32 AM


New To Site? Need Help?

All times are GMT. The time now is 12:35 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2