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 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
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?
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?
Try adding a pair of 47µF at 63V (or higher) in parallel with the main filter caps. The bass will sound much tighter.
Re: Correction AKAI AM 67 not 76 !
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 said:
Goetz said:
analog_sa said:
djk said:
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
Dear DJK,
thank you for your advice. With which other amps did you practised such parallel capacitors ?
Best regards
Goetz
thank you for your advice. With which other amps did you practised such parallel capacitors ?
Best regards
Goetz
Goetz said:
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.
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
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
djk said:
Is it possible to get tight bass in any amplifier by adding two 47uF capacitors?
Any other idea to get more tighter bass?
jaya000 said:
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)...
"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."
Obviously you haven't tried this.
If an amplifier has large electrolytics in the power supply, and no bypass caps, it sounds muddy.
The difference is not subtle.
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Edit Post Quote Reply Posted: September 01 2007 at 9:04am
The braking effect in a speaker system is largely the suspension stiffness, and the design of the box. The huge amount of air mass in a horn makes the driver stop pretty good.
'Damping factor' has little or nothing to do with it, largely because the Re of the driver destroys the facor to just over 1 even if the output impedance is zero from massive negative feedback.
Transients in music resemble a square wave. The large caps in amplifiers take a finite amount of time to dump the required current in the leading edge of the square wave. Adding a small bypass cap (usually 22uF~100uF) across each main filter cap will make the bass sound much 'tighter'. It will make no measureable difference in the power out, frequency response, of DF or the amplifier; yet it will change the sound more than you can imagine. Over 90% of all amplifiers do not have bypass caps. The ones with rock-hard bass do.
Even if your amplifier has bypass caps, they wear out quickly because of the huge currents involved. They seldom last more than a few years before needing replacement.
Obviously you haven't tried this.
If an amplifier has large electrolytics in the power supply, and no bypass caps, it sounds muddy.
The difference is not subtle.
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Quote _djk_
Edit Post Quote Reply Posted: September 01 2007 at 9:04am
The braking effect in a speaker system is largely the suspension stiffness, and the design of the box. The huge amount of air mass in a horn makes the driver stop pretty good.
'Damping factor' has little or nothing to do with it, largely because the Re of the driver destroys the facor to just over 1 even if the output impedance is zero from massive negative feedback.
Transients in music resemble a square wave. The large caps in amplifiers take a finite amount of time to dump the required current in the leading edge of the square wave. Adding a small bypass cap (usually 22uF~100uF) across each main filter cap will make the bass sound much 'tighter'. It will make no measureable difference in the power out, frequency response, of DF or the amplifier; yet it will change the sound more than you can imagine. Over 90% of all amplifiers do not have bypass caps. The ones with rock-hard bass do.
Even if your amplifier has bypass caps, they wear out quickly because of the huge currents involved. They seldom last more than a few years before needing replacement.
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