Why is digital bass so bad ? - diyAudio
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Old 27th August 2006, 01:56 PM   #1
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Default Why is digital bass so bad ?

I'm really looking for answers here. I've built and tweaked speakers and amps, pre amps, phono amps, bass modules and now turntable mods, all have been very successful so I have now turned my attention to digital sources but I am really baffled.

I have noticed as my system got better that cd and dvd players have problems, I have several but none are expensive, though I guess my collectable Sony CDP101 was in its day. All of them have bass that if you hear it in isolation is utterly horrible compared to my LPs/turntable.

I mean it is muffled, distorted, indistinct, lacking in any real musical quality and now everything else is working so well it just irks me no end.

I tried listening to the bass with the main speakers turned off and just the sub going to test it, I only tried two DVD players so far, a $40.00 Tevion and a $200.00 Panasonic, both terrrible, at first I though the Sub was faulty till I tried the turntable which was fine. Funnily enough the Tevion bad as it is creams the Panasonic from about 150hz up and the bass is better too so price is no inidcator here.

I got so messed up by this I even tried changing the opamps in the pre-amp, of course no better. To my ears the whole mess sounds a lot like clipping distortion.

Now I'm running only stereo not surround but just to rule out the pre amp I even tried the direct sub output from the players, bass was even worse.

I have not tested the CD players, they do sound better normally, though bass is still not great so I don't expect vastly better results. Of all the CD players the sony probably has the clearest/tightest bass but there's not much of it and the highs really sting too much!

I'm sure expensive CD players are better, though I always thought it was the highs that got better with higher pricetags, so I really hope it is the bass as well. Anyway I intend to mod some cheapies first to learn on, so what's the story, why so bad.

I am assuming the problem is likely power supply related, but maybe it something else, overall I reckon its the problem is from about 100hz down, it also seems to have some pretty strong harmonics mixed in with it from further up the frequency range. I'm sure about one thing just damping the case won't fix it.

Those black 12 inch discs and the surface noise that goes with them is starting to look better every day now! So somebody help me.
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Old 27th August 2006, 03:51 PM   #2
singa is offline singa  Singapore
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Default Why is digital bass so bad?

Why DVD sound bad is because they have switchmode power supply and have video circuits at 27Mhz.Plus lousy all in one chips.leave them aside and look for a cd player with a linear supply that will be an audio cd only machine.

Improve the power supply by replacing the rectifier diodes with fast soft recovery or schottky diodes and the noise bypass caps.Do it step by step to listen for result if you don't like it then restore back to original.Change the power filter caps to audio grade or low esr caps.Don't use sanyo Oscons trust me.Forget the standard BGs not worth the money.

At the opamp section or I/V stage use only polypropelene/polystryene caps and also the output coupling caps eg.Auricap,Mundorf supreme not Mcap but if can't afford then any similar type will do.But only round types that can fit into the area.Rectangular shape type if you can't find any but not prefered because such compressed type put stress on film/foil.Good luck.
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Old 27th August 2006, 11:44 PM   #3
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Thanks for the info, Id be glad to leave the DVDs alone except I want to record LPs to 24/96 format after editing them in soundtrack pro. Ive tried this and except for the bass issue the results are terrific. Is there any reason why the power supply for the average DVD could not be replaced entirely with an external one purpose built. I haven't checked the voltages to see what they are but looks like three seperate vs to me.

Assuming the DVD will not be used for pictures could for example the video precessing bit be disabled so it doesn't stuff the sound up, or is the sound tied up with this anyway?

The DVDs have digital outputs is this likely to improve the matter much, I don't have an external DAC so I can't test this.

I hear what you are saying regarding the CD players, they are far better to start with and none have switchmode supplies. I have trouble getting my head around the switchmode supplies but I have built some nice transformer based supplies that have worked beautifully in phono pre-amps and preamps. I am definitely doing the CD mods to start with.

Many thanks
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Old 28th August 2006, 12:25 AM   #4
singa is offline singa  Singapore
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[qoute] Assuming the DVD will not be used for pictures could for example the video precessing bit be disabled so it doesn't stuff the sound up, or is the sound tied up with this anyway?[/quote]

Unfortunately it's the cd audio vs dvd detection or routing of signal.
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Old 28th August 2006, 02:50 AM   #5
Leolabs is offline Leolabs  Malaysia
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Try something with "Pure Audio Only Mode".A few branded DVD players do have this feature.
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Old 28th August 2006, 01:31 PM   #6
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Most significent digital tweak (i tried all available tweaks): not using and disabling variable output (usualy connected to headphone)

replacing electrolitic output cap's for film types for much more detail in bas-region.

But a fully tweaked sony one-bitter cannot compete with original marantz cd-80 (no output cap's?) in bas output. So design matters as well.
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