They are handles for drawers. Home Depot or another similar store should have them. They are also threaded to accept a bolt, make sure you get the right thread.
Hello
I am having problems with the pots on the amplifier that I've posted here called tiny slug (comment number 120). The pots are soldered to the pcb using solid wires.
When I connected the amp there was no sound. Touching and moving the pot makes it work, but it is very difficult to find a position where it works. As soon as I leave the pot alone, it stop working again.... gggrrr.
Changed the pot and the same thing. All the pots seem to be a bit temperamental. I bought the pots from CPC and the brand is TT ELECTRONIC. I guess all the pots are having some sort of problem. The volume pot, and others, make a click when rotating.
I was looking at 500k log guitar volume pots and the cheapest ones are alpha pots ; CTS and BOURNS are expensive....
So I was wondering if someone knows good pots that are not super expensive.
Cheers,
Pedro
I am having problems with the pots on the amplifier that I've posted here called tiny slug (comment number 120). The pots are soldered to the pcb using solid wires.
When I connected the amp there was no sound. Touching and moving the pot makes it work, but it is very difficult to find a position where it works. As soon as I leave the pot alone, it stop working again.... gggrrr.
Changed the pot and the same thing. All the pots seem to be a bit temperamental. I bought the pots from CPC and the brand is TT ELECTRONIC. I guess all the pots are having some sort of problem. The volume pot, and others, make a click when rotating.
I was looking at 500k log guitar volume pots and the cheapest ones are alpha pots ; CTS and BOURNS are expensive....
So I was wondering if someone knows good pots that are not super expensive.
Cheers,
Pedro
Hi,
When I touch the wiper of the master volume pot, I can hear a loud hum. So the power stage is working well. One terminal of the master volume is connected to the tone stack, which is working well too when the master volume is working.
I will check for problems on the pre-amp.
Let's see ...
Thanks
When I touch the wiper of the master volume pot, I can hear a loud hum. So the power stage is working well. One terminal of the master volume is connected to the tone stack, which is working well too when the master volume is working.
I will check for problems on the pre-amp.
Let's see ...
Thanks
FWIW, I've used quite a few of the TT Electronics P160 series with no problems.
@Thomasha
Hi Thomas,
The sound when touching the wiper is normal. It is like touching the cable of the guitar. This was just to test the power amp.
Other thing that bothers me is that it is very very quiet. I have to go to 9 or 10 to hear something.
Maybe my RL resistors on the preamp are small (51k). I will increase these to 220k to increase the gain.
What do you think?
Thanks.
Pedro
Hi Thomas,
The sound when touching the wiper is normal. It is like touching the cable of the guitar. This was just to test the power amp.
Other thing that bothers me is that it is very very quiet. I have to go to 9 or 10 to hear something.
Maybe my RL resistors on the preamp are small (51k). I will increase these to 220k to increase the gain.
What do you think?
Thanks.
Pedro
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I would try to fix the problems with the preamp first. In this case with the pots.
They could be messing up with everything else. The clicking noises at the pots could be leaking caps. Check if there is any DC voltage at the pots.
A wrong resistor or a short could also result in excessive current, dropping the power line. I had a bad 12ax7 in a big amp, where the plate and grid were shorted resulting in weird results.
Quiet could also mean blocking distortion. But in that case things would get better at lower volume settings...
Ideally, I would disconnect as much of the circuit as possible and work with each stage separately to find the problem.
They could be messing up with everything else. The clicking noises at the pots could be leaking caps. Check if there is any DC voltage at the pots.
A wrong resistor or a short could also result in excessive current, dropping the power line. I had a bad 12ax7 in a big amp, where the plate and grid were shorted resulting in weird results.
Quiet could also mean blocking distortion. But in that case things would get better at lower volume settings...
Ideally, I would disconnect as much of the circuit as possible and work with each stage separately to find the problem.
@Thomasha
Thanks a lot for the answer. The click is mechanical, that is, I feel the click in my hand when rotating the pot.
I've checked the caps and none of them is leaking.
I think I will start by desoldering the pot and replace it with a resistor. If it works, it's the pot otherwise I will have to look further.
To debug the pre-amp I can use a small power amp and check if there is signal in the output of each preamp stage.
The sound that comes out, at this moment, is quiet and super distorted.
I will let you know the progress.
Cheers
Pedro
Thanks a lot for the answer. The click is mechanical, that is, I feel the click in my hand when rotating the pot.
I've checked the caps and none of them is leaking.
I think I will start by desoldering the pot and replace it with a resistor. If it works, it's the pot otherwise I will have to look further.
To debug the pre-amp I can use a small power amp and check if there is signal in the output of each preamp stage.
The sound that comes out, at this moment, is quiet and super distorted.
I will let you know the progress.
Cheers
Pedro
Hi guys
Today I have resoldered all pots. I still have to tilt the circuit to work (some bad contact anywhere I guess).
But now it works at a good volume.
Next things to solve
1 - find the bad contact
2 - the sound is very muddy and distorted. I found the bias is way off (close to 0V). Change the resistors and bias correctly.
3 - maybe after solving 2, this one will be solved, but the tone bank is doing nothing or very very little.
Cheers
Pedro
Today I have resoldered all pots. I still have to tilt the circuit to work (some bad contact anywhere I guess).
But now it works at a good volume.
Next things to solve
1 - find the bad contact
2 - the sound is very muddy and distorted. I found the bias is way off (close to 0V). Change the resistors and bias correctly.
3 - maybe after solving 2, this one will be solved, but the tone bank is doing nothing or very very little.
Cheers
Pedro
Hi,
I have another question.
Usually the transformer is connected to the highest voltage and then there are resistors that drop the voltage as we go in the direction of the preamp.
In my case, I would like the opposite: the 6N17B "likes high" voltages, whereas the 6N16B (output valve) doesn't.
Does it make sense to connect the pre-amp to, let's say, 220V and the power amp to 150V, or is this a silly idea?
My transformer can go up to 32kΩ, mismatching the output of the secondary, that is connecting my 8Ω speaker to the 4Ω tap. And that would allow me to go up to 170V, but if I want to push it to 250V, for example, the impedance of the transformer has to be even higher (64kΩ maybe), which I don't have right now (unless I had a 16Ω speaker and connected it to the 4Ω tap).
What do you think?
Cheers,
Pedro
I have another question.
Usually the transformer is connected to the highest voltage and then there are resistors that drop the voltage as we go in the direction of the preamp.
In my case, I would like the opposite: the 6N17B "likes high" voltages, whereas the 6N16B (output valve) doesn't.
Does it make sense to connect the pre-amp to, let's say, 220V and the power amp to 150V, or is this a silly idea?
My transformer can go up to 32kΩ, mismatching the output of the secondary, that is connecting my 8Ω speaker to the 4Ω tap. And that would allow me to go up to 170V, but if I want to push it to 250V, for example, the impedance of the transformer has to be even higher (64kΩ maybe), which I don't have right now (unless I had a 16Ω speaker and connected it to the 4Ω tap).
What do you think?
Cheers,
Pedro
The output will have less headroom than the preamp, meaning it will distort easier. Not necessarily bad for a guitar amplifier.
Why would you want this? Is the increase in output power considerable?
Do not forget, that the tubes have a maximum voltage. For the 6N16B it is 200V. See the Datasheet.
You don't want to have it reaching this level all the time.
@Thomasha
Hey Thomas,
You have a very nice and detailed instructable on the calculations for a PP amp using a 100V line transformer.
In your case you have the number of turns.
Now, here comes the idiot's question: if I want a different transformer for different power or price (line transformers are getting super expensive nowadays), how can I determine the centre tap for PP mode, if only the power is given?
I've found these cheap ones
https://cpc.farnell.com/eagle/p037s/100v-line-transformer-4w/dp/LS01704 (1,2,4W - shows in the image 0.5,1,2,4W)
https://www.digispot.co.uk/eagle-p037s--100v-line-transformer---4w-330917-p.asp (same as above, but only has the image and no tap information)
https://cpc.farnell.com/eagle/p635f/100v-line-transformer-30w/dp/LS01703?MER=sy-me-pd-mi-alte
Are these of any use for PP?
Cheers,
Pedro
Hey Thomas,
You have a very nice and detailed instructable on the calculations for a PP amp using a 100V line transformer.
In your case you have the number of turns.
Now, here comes the idiot's question: if I want a different transformer for different power or price (line transformers are getting super expensive nowadays), how can I determine the centre tap for PP mode, if only the power is given?
I've found these cheap ones
https://cpc.farnell.com/eagle/p037s/100v-line-transformer-4w/dp/LS01704 (1,2,4W - shows in the image 0.5,1,2,4W)
https://www.digispot.co.uk/eagle-p037s--100v-line-transformer---4w-330917-p.asp (same as above, but only has the image and no tap information)
https://cpc.farnell.com/eagle/p635f/100v-line-transformer-30w/dp/LS01703?MER=sy-me-pd-mi-alte
Are these of any use for PP?
Cheers,
Pedro