LM3875 Kit Finished - Could use some more bass

[jan.didden]

I think Daniel knows EXACTLY what he is talking about, and that he knows EXACTLY that it is all BS.

It is too consistent to be just stupidity. Therefore, I am of the opinion that Daniel is either playing a prank or is set out to have a few laughs on the expense of those who come here for valid answers.

In either case, it is despisable conduct.

Jan Didden

 

[paulb]

I think you're right, Jan. Despicable is another word that comes to mind.
Daniel, we've had enough now. You've wasted a lot of space on this forum and continually waste time from people who were trying to be helpful and straighten you out.

 

[danielwritesbac]

I think Daniel knows EXACTLY what he is talking about, and that he knows EXACTLY that it is all BS.
It is too consistent to be just stupidity. Therefore, I am of the opinion that Daniel is either playing a prank or is set out to have a few laughs on the expense of those who come here for valid answers.
In either case, it is despisable conduct.
Jan Didden

I think you're right, Jan. Despicable is another word that comes to mind.
Daniel, we've had enough now. You've wasted a lot of space on this forum and continually waste time from people who were trying to be helpful and straighten you out.

Are you two in favor of amplifying non audio signals
-or-
would you rather confine the input circuit of the amplifier to strictly the audio band?

Have you never heard of the practice of removing bandwidth that a woofer can't make in order to give it greater efficiency?

I beleve that both of those topics apply to input circuit -and- my sincere apologies if I am mistaken on that.

 

[BWRX]

Have you never heard of the practice of removing bandwidth that a woofer can't make in order to give it greater efficiency?

Neither of them are against that. If you actually took the time to read and understand their posts you would comprehend that. Please stop making bogus comments in order to circumvent the real argument.

 

[danielwritesbac]

Neither of them are against that. If you actually took the time to read and understand their posts you would comprehend that. Please stop making bogus comments in order to circumvent the real argument.

My studies have a lot to do with human hearing as well. If sub audio signals are combined "mashed together" with an audio signal, the result will be unclear audio. That can happen at the woofer, and subaudio will also harm a woofer's resolution, so the two topics are inseperable.

Ears work partially by dividing against subaudio signals (against, not with). That has to be done with precision, and not distorted by harmonics.
It would have been nice to avoid that topic, because I certainly don't have the skills to explain it.

I will click unsubscribe and post no further at this thread.

The kit designer, Peter Daniels has already published very specific information about preamplifier models and their importance to the kit, about power circuits options, and about filter caps.

On filter caps, he says BlackGate "N" 4.7uf, and since that is electrolytic, an optional polyproplene size would be found via dividing by 5 or 6 to get either 1uF for Wima MKP or 0.8uF for Wima MKP. Of course, I would prefer to use the exact parts recommended by the manufacturer, whenever those parts are available.

Peter has done such hard work, and its very good work too, so I can't help but insist that using the recommended size parts is the only reasonable place to start, but what I can do is leave this thread alone.

I wish everyone great success, and I apologise that I had such a hard time explaining anything.

 

[AndrewT]

I apologise that I had such a hard time explaining anything.

When input filter cap is overlarge, it can make loss of speaker driver control via allowing naturally present Theta (7.14hz) to enter the amplifier, become amplified and slow down the woofers. Of course, its easier just to say "use the right size" rather than try for an explanation.

Have you never heard of the practice of removing bandwidth that a woofer can't make in order to give it greater efficiency?

These two extracts from recent posts are not poor explanations.
These are completely at odds with any wisdom.
It's such a shame that for weeks now learners here on the Forum are having this shoved down their throats, and we have politely asked Daniel to reconsider.
But, it has finally hit the fan.

Bye Daniel.
Try unsubscribing from the Forum as well.
Come back when you have a question and not diatribe.

 

[audio1st]

I agree that Peter must know what he's doing.
I had the screech, distortion in the upper frequencies, showed up with Yes albums..
I very nearly added some 100nF bypassing caps to the power supply at the chips pins (resisted)..
Perfect now, just needed the running in time.
Could the bass be as simple as out of phase speaker wiring?

 

[dfdye]

Perfect now

And isn't that all that really matters???

 

[zdr]

The bass seems lacking compared to the commercial amp I was using, and the bass I get in some cases seems distorted and uncontrolled.

Your description seems to fit experience with my first 4780 gainclone. After numerous suggestions that led me nowhere, this deficiency cleared on it's own after some time. I was never quite a believer in burn-in, but it seems that those caps (ELNA 1500uF) close to IC needed just that. Just leave it running for a while and see what happens.

 

[johan851]

Thanks zdr, I'll try that. They're Panasonic FC, actually, but it may be the same kind of issue.

As for the banning, maybe I was right to trust my engineering instincts. I'm much less confused now.

 

[CarlosT]

Panasonic FCs are fine caps and yes...conditioning (or break-in) is important). I went with slightly better FM series which at 50v are only offered up to 1,000 uF. No problem here. With an unregulated PSU design, there's no free lunch...can't go stuffing huge caps. If you need to really thump away, better go back and find a good regulated PSU and put some serious rails of big caps. I think that was Carlos' eventual epiphany...NEED A REGULATED PSU and leave the amp board alone...

If I remember right one of Peter Daniel's favorite GCs runs on premium Blackgates of just 100 uF...

 

[Dxvideo]

A regulated example with turn on delay circuit..
Based on CarlosFM s reference design with LM338s.. But no snubbers on board.

An externally hosted image should be here but it was not working when we last tested it.

Firstly I was thinking to use 1,500uF/35v Panasonic FMs as first reservoirs. They have 2750mA ripple handle capacity. However by the time I've decided to put 10,000u because its more safe I guess..
Anyway, I think this circuit will enough for a stereo LM3875 gc with 28-30v...
Do you have any advice?