I'm just learning about electronics and how to correct audio problems. I recently upgraded my system with a highly detailed speaker (Mark Audio Alpair 10.3). I like the sonic characteristics - but I am hearing a "wavering" in the audio tone of long notes on vocal or guitar. I am thinking that it may have something to do with my source (jitter?). Or possibly a power supply issue?
My system:
Transport: Marantz CD 63 (unmodified)
DAC: Home-brew - DAC kit from China with CS4398 and CS8416 with output IC's replaced with Lampizator tube stage.
Amp: Simple SSE with upgraded OPT's (Edcor CXSE25-8-5k), plus Triad choke, plus 80uf motor run capacitor upgrades.
Speakers: Mark Audio Alpair 10.3 with Pensil cabinets
Any place I should look at for ways to identify the source of this problem? I'm a beginner, so a place to get educated on these types of problems might help.
Thanks for any insights!
Bill
My system:
Transport: Marantz CD 63 (unmodified)
DAC: Home-brew - DAC kit from China with CS4398 and CS8416 with output IC's replaced with Lampizator tube stage.
Amp: Simple SSE with upgraded OPT's (Edcor CXSE25-8-5k), plus Triad choke, plus 80uf motor run capacitor upgrades.
Speakers: Mark Audio Alpair 10.3 with Pensil cabinets
Any place I should look at for ways to identify the source of this problem? I'm a beginner, so a place to get educated on these types of problems might help.
Thanks for any insights!
Bill
It could be that the Lampizator stage is sending large amounts of ultrasonic images into the amp and causing intermodulation. Or it could be hum intermodulation. You won't hear digital jitter as 'wavering' unless it is astonishingly bad, which is unlikely. Is it Doppler distortion from the speaker?
My homebrew Lampizator modification made a very large impact on the musical quality of my previous, less revealing system (gainclone amp plus Mark Audio CHP-70 metronome speakers). Now that my system has improved, I notice that the almost non-audible hum from the Lampizator is now more noticeable. I will bypass my DAC and see if that is the cause.
I have limited capabilities with a scope. But I have a friend who might be able to help me here. That will be another approach.
No one mentioned my power supply. The CD63 doesn't have a ground on the power supply (2 prong plug). I am not confident that my mains AC is that clean. Maybe that will be the next thing to work on as I pursue "audio nirvana"!
Thanks for all your ideas.
I have limited capabilities with a scope. But I have a friend who might be able to help me here. That will be another approach.
No one mentioned my power supply. The CD63 doesn't have a ground on the power supply (2 prong plug). I am not confident that my mains AC is that clean. Maybe that will be the next thing to work on as I pursue "audio nirvana"!
Thanks for all your ideas.
On the list of "things which could possibly cause this problem," that's likely about #876,422.
Thanks Sy for the assurance that power issues are the least of my concerns!
I am very inexperienced in electronics. What I will attempt do is take a picture of my DAC (don't be too shocked - it will be ugly!) and maybe someone will have suggestions on how to clean things up/get rid of whatever is causing the hum/distortion in my Lampizator/tube output stage.
Thanks again for all your suggestions.
Best regards,
Bill
I am very inexperienced in electronics. What I will attempt do is take a picture of my DAC (don't be too shocked - it will be ugly!) and maybe someone will have suggestions on how to clean things up/get rid of whatever is causing the hum/distortion in my Lampizator/tube output stage.
Thanks again for all your suggestions.
Best regards,
Bill
I believe the unfiltered output of the DAC is fed to the tube (I may be wrong), on the implementations I have seen this was done with no real respect for the return current. As this signal has a high frequency content, the lack of coherent return path creates a lot of noise, as hinted to earlier by DF96.
Thanks for all your input.
I am going to do what I can: I bypassed the DAC and played my system without it. The sound was flatter, less dynamic. Surprisingly, the wavering on a extended note from a guitar still had the wavering, but much less. So maybe the Lampizator (in concert with the new Mark Audio 10.3's) only made the wavering more noticeable. That is, the wavering may be on the original CD.
I also noticed that without the DAC, the amp (Simple SSE) was dead quiet. I turned it up full blast, and dead silence. This is different than with the DAC - there is a definite hum.
In any case, I have included a picture of my DAC (remember I warned you - it will be ugly!). You will notice two toroidal transformers: the big one powers the original DAC with 2 voltages, the second powers the Lampinzator. The input comes from the DAC port on my CD63 into the original DAC.
I built the DAC before I built the Simple SSE. During the build of the amp, I heard of having a common ground point. I just noticed that the DAC grounds are all to the chassis, but at three different point. Is this a problem?
Being my first non-kit build, I also noticed that I didn't twist any of the wires. Maybe that could help.
Also, the wire that connects the output of the original DAC to the Lampizator is over 9 inches long. Could that be a problem?
Someone with much more experience could just look at my "project" (I use the term loosely) and see ways to improve it. I am open to suggestions.
Thanks again for all your input.
I am going to do what I can: I bypassed the DAC and played my system without it. The sound was flatter, less dynamic. Surprisingly, the wavering on a extended note from a guitar still had the wavering, but much less. So maybe the Lampizator (in concert with the new Mark Audio 10.3's) only made the wavering more noticeable. That is, the wavering may be on the original CD.
I also noticed that without the DAC, the amp (Simple SSE) was dead quiet. I turned it up full blast, and dead silence. This is different than with the DAC - there is a definite hum.
In any case, I have included a picture of my DAC (remember I warned you - it will be ugly!). You will notice two toroidal transformers: the big one powers the original DAC with 2 voltages, the second powers the Lampinzator. The input comes from the DAC port on my CD63 into the original DAC.
I built the DAC before I built the Simple SSE. During the build of the amp, I heard of having a common ground point. I just noticed that the DAC grounds are all to the chassis, but at three different point. Is this a problem?
Being my first non-kit build, I also noticed that I didn't twist any of the wires. Maybe that could help.
Also, the wire that connects the output of the original DAC to the Lampizator is over 9 inches long. Could that be a problem?
Someone with much more experience could just look at my "project" (I use the term loosely) and see ways to improve it. I am open to suggestions.
Thanks again for all your input.
Attachments
The wires that goes directly from the dac output (please confirm) should at least have a return path in very close proximity, preferably twisted pair or co-ax.
I presume they are the two thin brown wires?
Is there any filtering on the output of the DAC or have you bypassed it to go straight to the add on board?
I presume they are the two thin brown wires?
Is there any filtering on the output of the DAC or have you bypassed it to go straight to the add on board?
Your audio signal wires are single core wires. You need coaxial wires with the shielding of the wire connected to the grounds of the DAC and your tube stage. The wires that go from the output of the tube stage to the RCA connectors needs to be coaxial as well. I also notice that you are connecting the ground wires from the secondaries of your transformers to the chassis in 3 points but cannot make out a grounding scheme from the picture. Are your grounds connected correctly ? You might have floating grounds .
“A little knowledge is a dangerous thing.” I will respond to as many of your thoughtful responses as I can.
The basic method for this project is given in the Lampizator website here:
CD DAC Lampucera lampizator
The original (unmodified) DAC board did not require a ground. When I added the Lampizator, I got a ground loop. Once I grounded out both to the chassis, most of the hum went away. Possibly, I still have a ground issue/floating ground. I could use a common ground point (as opposed to the 3 chassis grounds points I am using). Would this be the “correct ground scheme” that you refer to rrremus (BTW, you can’t see it from the picture, but I have a wire directly from the mains ground to the chassis)?
Burning a CD with a 1kHz signal sounds like a great idea! I will try that if other ideas don’t work as well as hoped. My electronics friend may help me here with his knowledge of the O-scope.
I don’t believe that there is any filtering of the output from the DAC. The brown wires from the original DAC are the signal wires. They come from the L- and R- points on the board. There is no provision (per the above instructions) to use the L+ or the R+ points, assuming that is what you mean. This whole Lampizator idea is very non-conventional. But I like the sound.
The signal wires from the tube stage to the RCA outputs are unshielded. The RCA grounds are connected directly to the chassis. Maybe a common ground point will help here.
I do not have a second CD player to test. That would be useful to determine whether the wavering is from my player or simply on the CD.
If I missed the point on some of your comments, it is not intentional, but the result of my lack of electrical experience (I am a semi-retired accountant who got into this hobby just a few years ago, not an engineer!).
Thanks again to all. I will post as I make progress.
The basic method for this project is given in the Lampizator website here:
CD DAC Lampucera lampizator
The original (unmodified) DAC board did not require a ground. When I added the Lampizator, I got a ground loop. Once I grounded out both to the chassis, most of the hum went away. Possibly, I still have a ground issue/floating ground. I could use a common ground point (as opposed to the 3 chassis grounds points I am using). Would this be the “correct ground scheme” that you refer to rrremus (BTW, you can’t see it from the picture, but I have a wire directly from the mains ground to the chassis)?
Burning a CD with a 1kHz signal sounds like a great idea! I will try that if other ideas don’t work as well as hoped. My electronics friend may help me here with his knowledge of the O-scope.
I don’t believe that there is any filtering of the output from the DAC. The brown wires from the original DAC are the signal wires. They come from the L- and R- points on the board. There is no provision (per the above instructions) to use the L+ or the R+ points, assuming that is what you mean. This whole Lampizator idea is very non-conventional. But I like the sound.
The signal wires from the tube stage to the RCA outputs are unshielded. The RCA grounds are connected directly to the chassis. Maybe a common ground point will help here.
I do not have a second CD player to test. That would be useful to determine whether the wavering is from my player or simply on the CD.
If I missed the point on some of your comments, it is not intentional, but the result of my lack of electrical experience (I am a semi-retired accountant who got into this hobby just a few years ago, not an engineer!).
Thanks again to all. I will post as I make progress.
The link gives two 'Lampizator' circuits: a poorly designed cathode follower, and a cathode degenerated amplifier. The former will add distortion, and the latter will have too much gain. Which one have you built? Neither has any HF filtering, so I hope the DAC board does that.
A poorly-wired cathode follower can suffer from parasitic oscillation. Adding grid stoppers or cathode stopper resistors may help.
A poorly-wired cathode follower can suffer from parasitic oscillation. Adding grid stoppers or cathode stopper resistors may help.
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