Hi
i hope someone could guide please , my tube amp that i built dont give a sound when i turn it , the only sound i can get through the speakers is a buzz sound and when i turn the volumes the buzz get louder , when i plug a guitar it wouldnt give any sound but if i touch the strings it make a click sound , can anyone help ?
thanks
i hope someone could guide please , my tube amp that i built dont give a sound when i turn it , the only sound i can get through the speakers is a buzz sound and when i turn the volumes the buzz get louder , when i plug a guitar it wouldnt give any sound but if i touch the strings it make a click sound , can anyone help ?
thanks
Let me look in my crystal ball for you. The mist is fading . . .
It says you probably have a wiring error.
To get further than this we need more information: circuit diagram, some hint of your level of experience and available test equipment.
It says you probably have a wiring error.
To get further than this we need more information: circuit diagram, some hint of your level of experience and available test equipment.
the amp is a kit by weber the schematics below
https://taweber.powweb.com/store/lauren_schem.jpg
i did add another stage of pentode ef86 preamp below
https://taweber.powweb.com/store/ef86_schem.jpg
but without the capacitors and tone pot , just a coupling cap and then to volume
the output tube changed from 807 to 6l6 tube didnt change the cathode resistor 300ohm i kept everything as it is , the voltage on plate of the output is 427 v and the screen 327 v
i did check all the wiring , everything seems to be in its place
https://taweber.powweb.com/store/lauren_schem.jpg
i did add another stage of pentode ef86 preamp below
https://taweber.powweb.com/store/ef86_schem.jpg
but without the capacitors and tone pot , just a coupling cap and then to volume
the output tube changed from 807 to 6l6 tube didnt change the cathode resistor 300ohm i kept everything as it is , the voltage on plate of the output is 427 v and the screen 327 v
i did check all the wiring , everything seems to be in its place
when you touch the meter to the input grid on the output tubes, does it go "POW" in the speaker? If not, whynot? Back up one stage. Same test. Etc.
Warning, make measurements with one hand at a time. Connect the meter ground to the chassis with a clip lead to make this possible. Don't work high voltage alone. use a lot of light and don't work distracted by a cell phone etc.
You can work your way in from the input jack with an analog meter with a 2 VaC scale, and a 20 VAC scale. When you exercise the input with a FM radio on a rock station, can you see the beats of the music on the meter pointer? this requires a >450 V capacitor in series with the meter input, as AC analog voltmeters will read DC if you don't block it off.
Or a scope, but an analog voltmeter is a lot cheaper, and doesn't require 60 new electrolytic caps like the scope I bought on craigslist. The one where the boards are all glued in to the frame by the control rods and switches.
After you've proved the music goes in the first tube grid, does it come out the plate capacitor? Why not?
Warning, make measurements with one hand at a time. Connect the meter ground to the chassis with a clip lead to make this possible. Don't work high voltage alone. use a lot of light and don't work distracted by a cell phone etc.
You can work your way in from the input jack with an analog meter with a 2 VaC scale, and a 20 VAC scale. When you exercise the input with a FM radio on a rock station, can you see the beats of the music on the meter pointer? this requires a >450 V capacitor in series with the meter input, as AC analog voltmeters will read DC if you don't block it off.
Or a scope, but an analog voltmeter is a lot cheaper, and doesn't require 60 new electrolytic caps like the scope I bought on craigslist. The one where the boards are all glued in to the frame by the control rods and switches.
After you've proved the music goes in the first tube grid, does it come out the plate capacitor? Why not?
Wait.... you said that you replaced the 807 with a 6l6? What did you do with the anode lead? Did you remove it and wire it to the anode of the 6l6?
Also, you are running that 6l6 at darn near maximum plate voltage (450 is max per the JJ data sheet), so don't expect that tube to last very long the way you are running it.
You also said that you didn't change the cathode resistor. Is the bias still going to be the same for the 6l6 as the 807? I wouldn't think so since you are running at vastly different "normal" voltages.
What IndianaJo suggested is a great idea. Make sure you have a source going into it (cd player would be good). Do not run your amp without a load on the output.
Also, you are running that 6l6 at darn near maximum plate voltage (450 is max per the JJ data sheet), so don't expect that tube to last very long the way you are running it.
You also said that you didn't change the cathode resistor. Is the bias still going to be the same for the 6l6 as the 807? I wouldn't think so since you are running at vastly different "normal" voltages.
What IndianaJo suggested is a great idea. Make sure you have a source going into it (cd player would be good). Do not run your amp without a load on the output.
Does the EF86 stage replace the original ECC83 input stage or does it come before it? If the latter then you may just have too much gain.
By the way, this should be in Instruments & Amps forum.
By the way, this should be in Instruments & Amps forum.
i used the meter on the input grid of the output tube and it gave me such sound (pow) then went to the input grid of the 12ax7 V1A it gave me a scratch sound like but very light not like the (pow) ,on the V1B input grid gave me the (pow) sound , the ef86 in its input just scratch sound , the ef86 stage is not replaced with the 12ax7 and not after it actually i made it separately as in the schematic shown above one input but it has a coupling cap without the tone knob ,then goes to a volume and the output of the volume is connected to the driver 12ax7 V1B input grid , the V1A has two inputs and a tone a volume same as shown in the schematic of the amp its output volume connected to the input grid of the V1B driver .
however i did make measurements on the plate , which i did connect the blue lead that suppose to go to the 807 plate i connected to the plate of the 6l6 on that plate it gave me plate = 429v on the screen grid = 325v on the cathode that connected to the cathode resistor 300 ohm , it gave me 23v
i made my calculation i hope i'm right about it
429V - 23V = 406V
23V / 300 ohm = 0.076 ( 76ma )
0.076 * 406V= 31.12 watt
using 6l6GC , i know its limit is 30watt so yes in this case i'm taking it to its maximum , i know that i need to work on the cathode resistor and make it above the 300 maybe 400 ohm or even 500ohm , or maybe i change the tube to a KT88 cause it can take a 45watt max in this case but still the question is the amp dont make sound because i'm taking the 6l6 to its limits? i only hear buzz sound going up every time i turn the volume up and when i turn the volume down the buzz goes down .
however i did make measurements on the plate , which i did connect the blue lead that suppose to go to the 807 plate i connected to the plate of the 6l6 on that plate it gave me plate = 429v on the screen grid = 325v on the cathode that connected to the cathode resistor 300 ohm , it gave me 23v
i made my calculation i hope i'm right about it
429V - 23V = 406V
23V / 300 ohm = 0.076 ( 76ma )
0.076 * 406V= 31.12 watt
using 6l6GC , i know its limit is 30watt so yes in this case i'm taking it to its maximum , i know that i need to work on the cathode resistor and make it above the 300 maybe 400 ohm or even 500ohm , or maybe i change the tube to a KT88 cause it can take a 45watt max in this case but still the question is the amp dont make sound because i'm taking the 6l6 to its limits? i only hear buzz sound going up every time i turn the volume up and when i turn the volume down the buzz goes down .
All guitar amplifier threads belong in Instruments & Amplifiers by forum policy. Moving it.
Excess plate dissipation wattage on the output tubes will eventually burn holes in the plates, but not make it not sound until it does. Suggest you do as you indicate and take action (like bigger cathode resistor) to increase the postive voltage of the input grid of output tubes versus the cathode. I notice you didn't say you touched the input grids of the output tubes with your meter, and listen for the bang. Suggest you do so. No bang, some sort of wiring error is possible.
update.
Notice moderator has been busy. Welcome to the outer darkness with wailing and knashing of teeth. On I&A if Enzo and Salas are busy at work, you're often stuck with me, and my prefered instrument amp is the Hammond organ. Suggest you join music-electronics-forum.com where everybody works on guitar amps and organ amp owners like me are banned. Obviously, organ "music" is not music. Or maybe Hammonds don't use electrons, they use positrons or something.
update.
Notice moderator has been busy. Welcome to the outer darkness with wailing and knashing of teeth. On I&A if Enzo and Salas are busy at work, you're often stuck with me, and my prefered instrument amp is the Hammond organ. Suggest you join music-electronics-forum.com where everybody works on guitar amps and organ amp owners like me are banned. Obviously, organ "music" is not music. Or maybe Hammonds don't use electrons, they use positrons or something.
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A few questions.....
1) Specifically what version of the 6l6 are you using?
2) What is your schematic? Post it, it will help.
3) Did you modify the schematic at all during your build?
4) What plate voltages are you running on your driver tubes, the phase splitter (if you have one), etc...
5) Do you have anything at all shorted to ground?
6) What kind of output transformers are you using?
7) Do you have the output transformers isolated from the case? Do you have the power transformer isolated from the case? Do you have the choke isolated from the case if you are using one?
8) Do you have one leg of the output transformer secondary grounded? It will sound like crud if you don't.
9) What are you considering ground? Explain what you have for ground.
10) please post along with the schematic detailed pictures of your wiring. Be verbose with this because we are sort of guessing at what you have.
As a suggestion here.... you said that you were getting the popping sound on the output of your input tube. Check your wiring VERY carefully. Trace every wire and mark it on your schematic after you do.
1) Specifically what version of the 6l6 are you using?
2) What is your schematic? Post it, it will help.
3) Did you modify the schematic at all during your build?
4) What plate voltages are you running on your driver tubes, the phase splitter (if you have one), etc...
5) Do you have anything at all shorted to ground?
6) What kind of output transformers are you using?
7) Do you have the output transformers isolated from the case? Do you have the power transformer isolated from the case? Do you have the choke isolated from the case if you are using one?
8) Do you have one leg of the output transformer secondary grounded? It will sound like crud if you don't.
9) What are you considering ground? Explain what you have for ground.
10) please post along with the schematic detailed pictures of your wiring. Be verbose with this because we are sort of guessing at what you have.
As a suggestion here.... you said that you were getting the popping sound on the output of your input tube. Check your wiring VERY carefully. Trace every wire and mark it on your schematic after you do.
1. specifically a CED 6l6GC
2. schematics of the amp and the modification is in the first page already post them again i post them below
https://taweber.powweb.com/store/lauren_schem.jpg
ef86 preamp
https://taweber.powweb.com/store/ef86_schem.jpg
3. yes i did make the modify during the build not after
4. the voltage on the driver tube which is in the schematic is defined as V1B plate voltage = 172v
on the V1A plate voltage = 320v
on the ef86 plate voltage = 281v
5. i dont understand what u mean by shorted to ground , everything that needed to ground i did wire
6. the output transformer is weber WSE25 single ended 5k primary 25watt
7. yes they are isolated
8. yes the output transformer secondary is grounded
9.everything that shown in the schematics wire with a triangle wired to the ground
I'm a little vague why a website should use a secure https connection to show me a schematic diagram, so I'm following my browser's advice and not looking at the schematic on powweb.
The point of the pop in the speaker test is to focus your eyes on where the problem is. You work back from the output stage to the input, finding out where you don't have any response. If you do have response all the way back to the input, and you have the expected DC voltages on the plates pentode grids and control grids, then you move on to AC analysis. I would get a battery (ungrounded) FM radio, tune it to a rock station, wire the headphone output to a couple of .47 400v caps (hot and ground). Then pull the driver tube of the output tubes, connect the radio (caps outputs) to the control grid and the ground, see if music comes out. Okay? turn off, put the driver tube back in, pull the next tube back out (the one driving the driver tube), connect the radio to the control grid and ground of the driver, turn on. Got music? great. Not, whynot?
I got my battery radio out of the trash, one channel was dead and the slide pot was ****, so I put a fixed resistor in for the slide pot and only need one channel to debug amps with it. Cost $1.50 for two AA batteries, and a dead headphone I cut the plug off of. You can determine you are tuned to a rock station by listening with a good headphone before you put the test headphone plug in. The reason for rock music, you can see the beats on an analog VOM to discriminate music from possible RF oscillations caused by bad solder joints or wiring errors.
Note I don't use a tube tester, usually if the bias voltage on the grids are right by the tube datasheet, and the AC voltage in is a volt or two, music will come out the plate capacitor (or transformer for the output tubes). If you have an analog AC voltmeter (not a slow DVM) with a 2 VAC and 20 VAC scale (use capacitors to couple the +) (or a scope with a 10 x probe) you can measure the AC voltage in the control grid, the AC out the plate cap, divide by the plate plus cathode resistance, and figure the transconductance of the tube (which is on the datasheet). Transconductance out is current out (v/r) divided by voltage in.
Leaky gassy tubes will have low plate voltage compared to the print with the control grid bias voltage right due to too much current flowing through. Your tubes are new, so not very suspect, but shorts do happen in the first hour of tubes sometimes. Also some tube manufacturers have the reputation of not rebuilding their vacuum pumps often enough. Most new amateur amp builders have cold solder joints, or miswires, more commonly than tube or part failures.
The point of the pop in the speaker test is to focus your eyes on where the problem is. You work back from the output stage to the input, finding out where you don't have any response. If you do have response all the way back to the input, and you have the expected DC voltages on the plates pentode grids and control grids, then you move on to AC analysis. I would get a battery (ungrounded) FM radio, tune it to a rock station, wire the headphone output to a couple of .47 400v caps (hot and ground). Then pull the driver tube of the output tubes, connect the radio (caps outputs) to the control grid and the ground, see if music comes out. Okay? turn off, put the driver tube back in, pull the next tube back out (the one driving the driver tube), connect the radio to the control grid and ground of the driver, turn on. Got music? great. Not, whynot?
I got my battery radio out of the trash, one channel was dead and the slide pot was ****, so I put a fixed resistor in for the slide pot and only need one channel to debug amps with it. Cost $1.50 for two AA batteries, and a dead headphone I cut the plug off of. You can determine you are tuned to a rock station by listening with a good headphone before you put the test headphone plug in. The reason for rock music, you can see the beats on an analog VOM to discriminate music from possible RF oscillations caused by bad solder joints or wiring errors.
Note I don't use a tube tester, usually if the bias voltage on the grids are right by the tube datasheet, and the AC voltage in is a volt or two, music will come out the plate capacitor (or transformer for the output tubes). If you have an analog AC voltmeter (not a slow DVM) with a 2 VAC and 20 VAC scale (use capacitors to couple the +) (or a scope with a 10 x probe) you can measure the AC voltage in the control grid, the AC out the plate cap, divide by the plate plus cathode resistance, and figure the transconductance of the tube (which is on the datasheet). Transconductance out is current out (v/r) divided by voltage in.
Leaky gassy tubes will have low plate voltage compared to the print with the control grid bias voltage right due to too much current flowing through. Your tubes are new, so not very suspect, but shorts do happen in the first hour of tubes sometimes. Also some tube manufacturers have the reputation of not rebuilding their vacuum pumps often enough. Most new amateur amp builders have cold solder joints, or miswires, more commonly than tube or part failures.
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before i connect the radio and try it the way indianajo explained i just replaced the 6l6 with a KT88 and i did measure the voltages on it and the driver and preamp tubes section so these are details for the voltages
KT88
plate = 417.5v
cathode = 24 v
screen = 296.5v
cathode R= 300 ohm
V1B the driver
plate = 159.8v
cathode = 1.1v
cathode R = 1k
V1A (preamp)
plate = 280v
cathode = 124v
cathode R = 1.5k
EF86 (preamp)
plate = 245.7v
cathode = 124.2v
cathode R = 2.2k
i dont understand why i have 124v on the cathode in both preamp section
KT88
plate = 417.5v
cathode = 24 v
screen = 296.5v
cathode R= 300 ohm
V1B the driver
plate = 159.8v
cathode = 1.1v
cathode R = 1k
V1A (preamp)
plate = 280v
cathode = 124v
cathode R = 1.5k
EF86 (preamp)
plate = 245.7v
cathode = 124.2v
cathode R = 2.2k
i dont understand why i have 124v on the cathode in both preamp section
I would have to say the driver, preamp and EF86 cathode voltages look very high. I would wonder what the bottom, the ground side, of each cathode resistor was reading. I wonder if the path back to the power transformer is correct.
now i checked the ground and it appears one of the wire is broken so i solder it again
this time i have SOUND !!!!! and its LOUD!!! specially the buzzzzzz , i did measure this time the cathode voltages and here it is
the V1A (preamp) = 1.442v
the V1B (driver) = 1.07v
the ef86 (preamp) = 1.7v
now after i got a sound from my guitar i have last problem the BUZZ , its HUGE BUZZ and even the amp is so much loud for a single ended
one thing i noticed is that when i touch the chassis the buzz become less and when i take my hand it increase but still there is a huge buzz even if i touch the chassis so i need more to check but any ideas what it could be?
thanks by the way
this time i have SOUND !!!!! and its LOUD!!! specially the buzzzzzz , i did measure this time the cathode voltages and here it is
the V1A (preamp) = 1.442v
the V1B (driver) = 1.07v
the ef86 (preamp) = 1.7v
now after i got a sound from my guitar i have last problem the BUZZ , its HUGE BUZZ and even the amp is so much loud for a single ended
one thing i noticed is that when i touch the chassis the buzz become less and when i take my hand it increase but still there is a huge buzz even if i touch the chassis so i need more to check but any ideas what it could be?
thanks by the way
Okay, you've found & fixed that soldering error. Hum usually comes from open inputs (control grids) or faulty grounds. One usually finds the bad area by shorting the inputs (control grids) of the following stage. You can't just short the grid of a tube itself to ground, it has a DC voltage bias network that might be damaged. So you short the signal to ground before the DC blocking capacitor to the control grid. You start at the output tubes and work backwards. As far backwards as you get with no hum, the stage before that is messed up. Watch and don't short a plate to ground either, the plate resistor could be burnt by shorting to ground, too.
Checking the wiring after construction is not a visual experience. You get a copy of the schematic, and a buzzer or beeper, and check continuity of each wire in the schematic diagram. You touch the component lead, not the wire, in case the joint is cold. You color them off on the diagram with a yellow pencil as you go. The one that doesn't beep, has a soldering or wiring error. I realize you can't touch the tube pins, but in case you have a tube socket not touching the tube control grid pin, you can pull the tubes out and buzz from the top side of the socket. Old work often has corroded tube socket metal, or tube pins, and they have to be erased and washed with alcohol, or poked out with a sharp pick. (power off, caps discharged to zero). Your amp is new work so I don't really suspect corrosion of the brass or tin is a big issue.
If you actually prepared a wirelist, of wires and where they start and where they end, you can count wires on each point as you buzz it out and any that have extra wires that aren't on the wirelist are an error. A wirelist is a text document that has a start point and an end point for each wire. Each point in the amp has a name. Continuous strings have an origin with one termination, and two entries for each point that has two wires on it. Tube point to point wiring of course, some points can have many wires on them. there is a wirelist entry (source, end) for each wire on the point. Factories that hand build actually use wirelists instead of schematics. The routing matters of a signal, you don't want the solder operators making up the routing without thought. No high level signals parallel to low level signals, no high AC current wires parallel to wires to high gain points (like control grids).
Checking the wiring after construction is not a visual experience. You get a copy of the schematic, and a buzzer or beeper, and check continuity of each wire in the schematic diagram. You touch the component lead, not the wire, in case the joint is cold. You color them off on the diagram with a yellow pencil as you go. The one that doesn't beep, has a soldering or wiring error. I realize you can't touch the tube pins, but in case you have a tube socket not touching the tube control grid pin, you can pull the tubes out and buzz from the top side of the socket. Old work often has corroded tube socket metal, or tube pins, and they have to be erased and washed with alcohol, or poked out with a sharp pick. (power off, caps discharged to zero). Your amp is new work so I don't really suspect corrosion of the brass or tin is a big issue.
If you actually prepared a wirelist, of wires and where they start and where they end, you can count wires on each point as you buzz it out and any that have extra wires that aren't on the wirelist are an error. A wirelist is a text document that has a start point and an end point for each wire. Each point in the amp has a name. Continuous strings have an origin with one termination, and two entries for each point that has two wires on it. Tube point to point wiring of course, some points can have many wires on them. there is a wirelist entry (source, end) for each wire on the point. Factories that hand build actually use wirelists instead of schematics. The routing matters of a signal, you don't want the solder operators making up the routing without thought. No high level signals parallel to low level signals, no high AC current wires parallel to wires to high gain points (like control grids).
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