Still Buzzing...
Yesterday I installed larger, higher quality filter caps (220uf, 220uf, 100uf 350v) to replace the originals, hoping that this might help reduce the noise in my amp (buzzing). And no luck... To date I have installed: new filter caps, cap across HV transformer leads, high quality PP film coupling caps, 1uf PP bypass cap for largest filter cap, and bleeder resistors for filter caps. These mods have improved SQ, lowered overall noise, but still have not rid me of that stupid buzz! Help!
Yesterday I installed larger, higher quality filter caps (220uf, 220uf, 100uf 350v) to replace the originals, hoping that this might help reduce the noise in my amp (buzzing). And no luck... To date I have installed: new filter caps, cap across HV transformer leads, high quality PP film coupling caps, 1uf PP bypass cap for largest filter cap, and bleeder resistors for filter caps. These mods have improved SQ, lowered overall noise, but still have not rid me of that stupid buzz! Help!
Buzz removal
After looking at your amp I have a feeling that the configuration or your output transformers and supply transformer need to be in line with the board. Try to keep the wires from intersecting. It's best to have the cleanest line between transformer and board. Your amp looks cool. I am building another for a friend and will try the plexi top. Nice touch.
"The shortest distance between two points is a straight line".
After looking at your amp I have a feeling that the configuration or your output transformers and supply transformer need to be in line with the board. Try to keep the wires from intersecting. It's best to have the cleanest line between transformer and board. Your amp looks cool. I am building another for a friend and will try the plexi top. Nice touch.
"The shortest distance between two points is a straight line".
Hi, From the earlier photo that was posted there is one area that can and almost always will cause hum. That is the arrangement of the transformers. They will mutually couple if the cores have the same allignments (as in the photo). Without test gear it is difficult to get the optimum arrangement, but having the power and output transformers at right angles to each other is often very close. The lack of shielded signal interconnections is another likely source of hum. This is particularly true in non-metalic chassis. Volume and tone control pots in such chassis should also be grounded (if possible) as they will pick up hum and noise and feed it into the signal at the control. Additional power supply filtering over what you have now is unlikely to be of great benefit. The key to this is that the level of hum and noise increases with the gain setting. Another common problem with amps like this (others too) is the location of the grounds for the signal inputs. Depending on how it is done a ground loop can occur.
Hi,
from an earlier post I remember that the problem of zcables' amp is not hum but a buzzing sound.
IMHO this argues against any coupling of transformers or a grounding problem. Buzzing noises are usually switching spikes from the rectifier diodes and the main transformer. Upgrading the rectifier diodes should help a lot.
If it is indeed the typical 50/60Hz hum I second gofar99: Rotating the transformers and shielding any small signal cable should help. Grounding the pot cases is a MUST in many cases.
Good luck!
Martin
from an earlier post I remember that the problem of zcables' amp is not hum but a buzzing sound.
IMHO this argues against any coupling of transformers or a grounding problem. Buzzing noises are usually switching spikes from the rectifier diodes and the main transformer. Upgrading the rectifier diodes should help a lot.
If it is indeed the typical 50/60Hz hum I second gofar99: Rotating the transformers and shielding any small signal cable should help. Grounding the pot cases is a MUST in many cases.
Good luck!
Martin
Thank you
Smarter people than me.
I have read comments in favor and against upgrading the br. With a limited understanding of Ohm's law, is it a quality issue and not the actual value of the rectifier that is in question? Someone else wrote the to help me understand- " To water your yard, it doesn't take a fire hose."
Smarter people than me.
I have read comments in favor and against upgrading the br. With a limited understanding of Ohm's law, is it a quality issue and not the actual value of the rectifier that is in question? Someone else wrote the to help me understand- " To water your yard, it doesn't take a fire hose."
Hi, The situation with rectifiers generally relates to what happens when they shut off. That is after the conduction part of the cycle. Two things tend to happen depending on the actual rectifier and the associated circuitry. If the rectifier is slow to turn off (like the 1N4000 series) there can be a fairly large reverse flow of current back into the transformer. This can be seen on an oscilloscope as a distortion in the wave forms. It can cause odd sounding artifacts in the sound. The usual fix is to use "fast turn off" rectifiers". This can casue problems as well. They can generate rather sharp spikes in the B+ line. Fortunately, this is easier to control. The .1 to 1uf bypass capacitors in parallel with the electrolytics can usually remove the spikes. Additional measures such as small capacitors across the rectifiers and across the secondaries of the transformer can also work. The actual current and voltage ratings of rectifiers are not specifically related to the issue, except generally as the higher the voltage rating, it seems the slower the turn off speed. The best compromise I have found (IMHO) is in the 100-200 ns turn off speed. Good prices, few problems.
Buzzing.....
I noticed a lot of posts on this thread about the S-5 and problems with buzzing. I built the K-16LS and had a buzzing problem, even after considerable messing around with better caps, shielding, and whatnot. Ended up getting rid of the buzz by building a tube type power supply with a RCA 5U4GB rectifier tube for my amp. Not only did the buzz go away, but I have a better sound now as well, the bass is definitely richer and so are the midtones. Treble seems to be about the same. (Sorry, this is all just by ear, no scope available) Hope this gives someone a good idea!
I noticed a lot of posts on this thread about the S-5 and problems with buzzing. I built the K-16LS and had a buzzing problem, even after considerable messing around with better caps, shielding, and whatnot. Ended up getting rid of the buzz by building a tube type power supply with a RCA 5U4GB rectifier tube for my amp. Not only did the buzz go away, but I have a better sound now as well, the bass is definitely richer and so are the midtones. Treble seems to be about the same. (Sorry, this is all just by ear, no scope available) Hope this gives someone a good idea!
photos and schematics
Photos are easy, they are on my Flickr site:
http://flickr.com/photos/meralalin
Go to the collection marked "tubes".
Schematic might take me a little longer, but give me a day or so and I will come up with it.....I moved to a new house since I built the amp...
Still unpacking!
Oh, and one more thing I did to the amp that slowed down the noise was locating the power supply in a remote box beside the tube board. Gets all of the ac power except the filament power away from the tubes so there is no HV RF to cause noise. As for the changes in caps, upgraded to orange drops, and sprague atom on power supply. Also used the old caps from the kit for snubbers on the filaments. Didn't see much difference when I installed the snubbers.
Photos are easy, they are on my Flickr site:
http://flickr.com/photos/meralalin
Go to the collection marked "tubes".
Schematic might take me a little longer, but give me a day or so and I will come up with it.....I moved to a new house since I built the amp...
Still unpacking!
Oh, and one more thing I did to the amp that slowed down the noise was locating the power supply in a remote box beside the tube board. Gets all of the ac power except the filament power away from the tubes so there is no HV RF to cause noise. As for the changes in caps, upgraded to orange drops, and sprague atom on power supply. Also used the old caps from the kit for snubbers on the filaments. Didn't see much difference when I installed the snubbers.
Schematics
Didn't take as long to find as I thought! Here is the schematic:
Power Supply Schematic
One of the main changes I would make to this is the C2 value, I would up it to 250uf. However at the time 100uf was what I had, and it works nicely. This is basically a power supply I found here:
Gabes Tubes
To install the power supply into the amp, I removed the old transformer, C10 and C11, as well as the silicone rectifier then plugged the HV into the +/- where the rectifier was. The tube
heater voltage simply goes into the board where it always did, and I twisted the leads the entire length to lessen AC interference. In the power supply box, I used a star ground system to ground everything including transformers, chokes, switches, basically anything that could make a ground loop.
Also on the AC power supply, I used a three prong grounded supply, and also put snubber caps on that. I don't remember what I used there, I robbed the AC input off of an old computer power supply for the cables and caps. There was a 1H choke in the original 115V power supply, but I did not use that.
OOPS!!! Wrong link to the Flickr Page on previous Post!!!!
Sorry, here is the correct one:Flickr
Didn't take as long to find as I thought! Here is the schematic:
Power Supply Schematic
One of the main changes I would make to this is the C2 value, I would up it to 250uf. However at the time 100uf was what I had, and it works nicely. This is basically a power supply I found here:
Gabes Tubes
To install the power supply into the amp, I removed the old transformer, C10 and C11, as well as the silicone rectifier then plugged the HV into the +/- where the rectifier was. The tube
heater voltage simply goes into the board where it always did, and I twisted the leads the entire length to lessen AC interference. In the power supply box, I used a star ground system to ground everything including transformers, chokes, switches, basically anything that could make a ground loop.
Also on the AC power supply, I used a three prong grounded supply, and also put snubber caps on that. I don't remember what I used there, I robbed the AC input off of an old computer power supply for the cables and caps. There was a 1H choke in the original 115V power supply, but I did not use that.
OOPS!!! Wrong link to the Flickr Page on previous Post!!!!
Sorry, here is the correct one:Flickr
Using an oscilloscope we have noticed a high frequency oscillation burst (20 kHz) that is repeated at a 60Hz rate. It is worse at the mid-preamp gain settings. This seems to account for most of the residual "hum" after rotating the transformers and some of the other suggested modifications. The bursts are present even when the inputs are tied resistively to ground through 2.2k resistors. The input cables are removed, so there is no opportunity for the input to be near the output.
Has anyone else noticed this?
This seems to be a stability problem that is either inherent in the amplifier design, pcb layout or ground/cable routing.
Has anyone else noticed this?
This seems to be a stability problem that is either inherent in the amplifier design, pcb layout or ground/cable routing.
Hi,
I have been reading everything I can about this amp and decided to order the amp and tone control which will arrive on 11/26. I would like to build it with a few mods from the start but I'm a little unclear on which parts to get exactly (type,spec and brand). I want to do the rectifier upgrade, the resistors for the caps (which are for safety correct?)and I would also like to replace all the caps (power and audio). Would replacing the other resistors do anything ?
I have electronics experience but I'm very much a amateur so any help and guidance is greatly appreciated.
Thank you for your time,
Bob
I have been reading everything I can about this amp and decided to order the amp and tone control which will arrive on 11/26. I would like to build it with a few mods from the start but I'm a little unclear on which parts to get exactly (type,spec and brand). I want to do the rectifier upgrade, the resistors for the caps (which are for safety correct?)and I would also like to replace all the caps (power and audio). Would replacing the other resistors do anything ?
I have electronics experience but I'm very much a amateur so any help and guidance is greatly appreciated.
Thank you for your time,
Bob
Cool!
It's a great amp that puts out a big beautiful sound. I am just a newbie also and have most of my experience from restoring old pinball machines and have just recently joined the ranks of "Tube Heads". For the same reason that had drawn me to old pins I have a deep passion for the creative side of tubes. They can be many things to many people due to the wide range of sounds that can be made. Transistors are great and there is no doubt that we could not exist without them but they cannot replace the warmth and feel of a tube. Many argue this point but in the end, I know what I like.
Yes, the resistors are for safety only and serve that purpose only after the amp is powered down. As long as you have the caps energized, they will discharge at the easiest point to ground (which can be your body).
A resistor in this application is like putting a small hole in a balloon. The stored energy is released slowly. Where as if you were to touch the exiting lead.....Pop! HIGH VOLTAGE CAN KILL YOU!
The small rectifier that came with the kit has been fine for me. I would stick with this one until you have at least burned in your amp. If then you feel the need to reduce noise (if any), I would do it then.
Ruby Gold caps are what I used and have made the biggest improvement in bass for the money at just under $25. I am just a dummy still trying to understand amplification theory and from what I gather is that a bigger cap is way of reserving more energy for when the time requires it, and low end (20 hertz) is a big drain.
The Edcor opt have made a big difference also but the cost was over $100 and I feel that the money would have been better spent on my next project. I may reinstall the old ones and use the Edcors in my next one anyway.
I would also use the best soldier I can get my hands on. The soldier joints make a huge difference. Kister brand flux core 69/31. Proper iron heat is a good idea but the pcb (printed circuit board) supplied is very durable and not prone to lifting traces.
Again, I am just as new to this as you so my advice is very basic and may be a little painful for some to read due to the nature. In the immortal words of Dr. McCoy, "Dammit Jim!".
Have fun.
It's a great amp that puts out a big beautiful sound. I am just a newbie also and have most of my experience from restoring old pinball machines and have just recently joined the ranks of "Tube Heads". For the same reason that had drawn me to old pins I have a deep passion for the creative side of tubes. They can be many things to many people due to the wide range of sounds that can be made. Transistors are great and there is no doubt that we could not exist without them but they cannot replace the warmth and feel of a tube. Many argue this point but in the end, I know what I like.
Yes, the resistors are for safety only and serve that purpose only after the amp is powered down. As long as you have the caps energized, they will discharge at the easiest point to ground (which can be your body).
A resistor in this application is like putting a small hole in a balloon. The stored energy is released slowly. Where as if you were to touch the exiting lead.....Pop! HIGH VOLTAGE CAN KILL YOU!
The small rectifier that came with the kit has been fine for me. I would stick with this one until you have at least burned in your amp. If then you feel the need to reduce noise (if any), I would do it then.
Ruby Gold caps are what I used and have made the biggest improvement in bass for the money at just under $25. I am just a dummy still trying to understand amplification theory and from what I gather is that a bigger cap is way of reserving more energy for when the time requires it, and low end (20 hertz) is a big drain.
The Edcor opt have made a big difference also but the cost was over $100 and I feel that the money would have been better spent on my next project. I may reinstall the old ones and use the Edcors in my next one anyway.
I would also use the best soldier I can get my hands on. The soldier joints make a huge difference. Kister brand flux core 69/31. Proper iron heat is a good idea but the pcb (printed circuit board) supplied is very durable and not prone to lifting traces.
Again, I am just as new to this as you so my advice is very basic and may be a little painful for some to read due to the nature. In the immortal words of Dr. McCoy, "Dammit Jim!".
Have fun.
Caps at the filter stage. 220,100,22 mfds
These caps can be found at http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=020-658 and are an easy install. I would have preferred using radial caps that did not require extending the leads and using heat shrink tubing to isolate them. If you need the part number for the Edcors, let me know. I am now wondering if I can add a little muscle from a different power supply. If anyone knows or has a suggestion, I am interested.
These caps can be found at http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=020-658 and are an easy install. I would have preferred using radial caps that did not require extending the leads and using heat shrink tubing to isolate them. If you need the part number for the Edcors, let me know. I am now wondering if I can add a little muscle from a different power supply. If anyone knows or has a suggestion, I am interested.
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