so going from 4Uf to 10Uf, as I've done, should this give a lower cut off point and hence is this an improvement?
also another thing bothering me is the slight hum I'm getting. Could this just be a bad powe supply?
It disappearrs when I switch the buffer off and leave the amp on.
also another thing bothering me is the slight hum I'm getting. Could this just be a bad powe supply?
It disappearrs when I switch the buffer off and leave the amp on.
Dr. Pass,
Is there any way the change in cap from 4Uf to 10Uf could have led to a DECREASE in bass?
Because that's what appears to have happened although I don't know why.
Is there any way the change in cap from 4Uf to 10Uf could have led to a DECREASE in bass?
Because that's what appears to have happened although I don't know why.
Another question is regarding the hum I just mentioned:
It would vary in loudness from audible at sitting position, to inaudible until I went up close to the woofer, depending on how I wiggled the connection on the amp, so I figured there must be a faulty connection and replaced the socket but now, the hum is low level and constant.
Why would the hum vary?
It would vary in loudness from audible at sitting position, to inaudible until I went up close to the woofer, depending on how I wiggled the connection on the amp, so I figured there must be a faulty connection and replaced the socket but now, the hum is low level and constant.
Why would the hum vary?
Professor smith said:
You may want to read this:
http://www.passdiy.com/pdf/articles/ground-loops.pdf
It's stretching credibility, but if 4uF+100% and 10uF-20% were the swap then both should have the same LF impedance.
but can you help me to sort this out, not long ago, I was getting very nice sound from the set up but after a few changes, now the bass is less deep and the treble has become harsh.
The only major changes I can think of are:
1)I removed a small value coupling cap on the input which was there.
2) changed output dc cap from 4Uf to 10Uf as Ive said.
what do you think?
The only major changes I can think of are:
1)I removed a small value coupling cap on the input which was there.
2) changed output dc cap from 4Uf to 10Uf as Ive said.
what do you think?
Professor smith said:
Why not try reversing these two changes one at a time to see which (if either of them) is the culprit?
-d
The capacitor is double the size so it must be 10Uf, yes I'm sure.
Why not try reversing these two changes one at a time to see which (if either of them) is the culprit?
I will try that but it doesn't make sense. The reason I changed it to 10Uf in the first place was to get even more bass but instead I got the opposite effect. I dont understand.
Why not try reversing these two changes one at a time to see which (if either of them) is the culprit?
I will try that but it doesn't make sense. The reason I changed it to 10Uf in the first place was to get even more bass but instead I got the opposite effect. I dont understand.
please can someone help me?
I cant get the same sound back as I had before and I'm very disappointed.
I have changed it back to the original capacitance values but still things don't sound as good as before.
I have not put back the input cap which was there previously however I don't see how this could affect the bass.
I cant get the same sound back as I had before and I'm very disappointed.
I have changed it back to the original capacitance values but still things don't sound as good as before.
I have not put back the input cap which was there previously however I don't see how this could affect the bass.
Professor smith said:
I assume this is the preamp layout as it sits/ lays today?
Is that a pillow ? 🙂
http://www.diyaudio.com/forums/showthread.php?postid=1608585#post1608585
You may want to wire this up on a perfboard with a neat but compact and tight layout, and then stick it in a case. Those big loops of unshielded wire in low level signal runs can pick hum from close by sources, especially overhead lights. You may also want to thoroughly clean all your connectors in the entire system, and double check all wiring for cold solder joint/bad connections, especially in the grounds and at the large power caps.
I've had many problems in the past with projects or tests wired up with long jumpers. A breadboard with short wires works better.
actually I have put the whole thing into a case now.
But previously, yes it was point to point wiring and laid on a pillow in that picture.
I have also shortened the wires and crammed it into a box.
The thing is, it works. The only trouble is, it doesnt sound as good, ie the bass is not as deep, the treble is harsh, dynamics arent as big. But previously, I was happy with the way the bass was sounding.. the treble was also fine.
But previously, yes it was point to point wiring and laid on a pillow in that picture.
I have also shortened the wires and crammed it into a box.
The thing is, it works. The only trouble is, it doesnt sound as good, ie the bass is not as deep, the treble is harsh, dynamics arent as big. But previously, I was happy with the way the bass was sounding.. the treble was also fine.
Look for the grounding of the signal. Zen Mod published the schematics for the version of the B1 with symmetric PS anywhere in this thread. He noted the proper grounding scheme there too.
I had the problem while measuring my incarnation of the B1: The grounding of the signal (to the groung of the PS) lost its contact the signal still passed the B1 but with a low level and very high distortion. To my surprise there was almost no hum so I did a search in the wrong direction in the beginning. The B1 seems to react to faulty grounding in this (in my opinion) unconventional way.
Best regards
Flo
I had the problem while measuring my incarnation of the B1: The grounding of the signal (to the groung of the PS) lost its contact the signal still passed the B1 but with a low level and very high distortion. To my surprise there was almost no hum so I did a search in the wrong direction in the beginning. The B1 seems to react to faulty grounding in this (in my opinion) unconventional way.
Best regards
Flo
Floric said:
can you explain that again please, it sounds like this could be the problem.
I also have intermittent hum..
You have to do a proper grounding. That means, that the ground from the signal and the ground of your power supply sould meet in ONE point.
Look at Zen Mod's pictue in post no. 285, the B1 with symmetric powersupply. http://www.diyaudio.com/forums/attachment.php?s=&postid=1569192&stamp=1216943305
The ground of your chinch-input for the right channel should connect to the lower side of R100 (R200 for the left channel). Follow this rail, you will see, that it connects to one point in the right of the picture. That point is connected to the ground of the powersupply (the ground-symbol). It is called the "star ground". From that point there should be a wire to the lower side of R105 as you see in the picture. Connect your chinch-output to "out" and the ground out the output-connector to the lower side of R105. Same for the other channel.
If there is already a connection from the lower side of R100 to the lower side of R105 in your setup then connect only one of those points to the star-ground.
Do this (one of those solutions) before you try anything else!
Best regards
Flo
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