Ok, tried with all tubes and the dummy load. The voltages drop quite nicely, measured to ground:
1st filter cap: 362V
2nd filter cap: 318V
3rd filter cap: 258V
preamp plates were:
1st triode: 115V
2nd triode: 106V
I think now it seems that it's in the ball park, though the preamp voltages are quite low.
old thread
Moderators: pompeiisneaks, Colossal
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Andy Le Blanc
- Posts: 2582
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- Location: central Maine
how the hell did I drop it out of the amp's ass
anyone who has learnd this craft without a formal education
in the craft has gone thru moments just like yours
its a challenge and a learning curve....now you know
its a good thing........... I still dont know how I got my first amp to go
it was a leap in the dark
in the craft has gone thru moments just like yours
its a challenge and a learning curve....now you know
its a good thing........... I still dont know how I got my first amp to go
it was a leap in the dark
lazymaryamps
Re: old thread
Back to work.
How do I get the 6N1P voltages up? How can I lower the 6AQ5 voltages? What if I construct a heat sink for it, will it save the poor little tube?
How do I get the 6N1P voltages up? How can I lower the 6AQ5 voltages? What if I construct a heat sink for it, will it save the poor little tube?
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Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: old thread
being aware of the circuit conditions is half the battle
with the power tube be aware that it gets enough ventilation
this is the same for all power tubes reguardless of size
if it becomes a significant issue.....scrouge up a small fan
to vent the amp.....there are plenty of examples with chassis fans
where did you measure the voltages around the preamp tube?
there will be a difference of measured voltage on either side
of the plate resistor.... the supply voltage at the filter cap
looks ok.....the voltage drop of the plate resistor is responsible
in part, for the gain of that stage of the amp....
with the power tube be aware that it gets enough ventilation
this is the same for all power tubes reguardless of size
if it becomes a significant issue.....scrouge up a small fan
to vent the amp.....there are plenty of examples with chassis fans
where did you measure the voltages around the preamp tube?
there will be a difference of measured voltage on either side
of the plate resistor.... the supply voltage at the filter cap
looks ok.....the voltage drop of the plate resistor is responsible
in part, for the gain of that stage of the amp....
lazymaryamps
Re: old thread
I measured the preamp voltages after the 100k resistors going to the socket, the point where 100k and the 0.022uf caps are connected.
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Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: old thread
its the supply voltage at the 3rd filter that feeds the two 100k resistors
on your layout....... things look like they'll work ....
when you hear the amp..... you will have an chance to see how changeing
the supply voltage will affect the amps tone... the resistor between the
2nd and 3rd filter cap can be parallel'd to reduce its value temporarly
to raise the volts.....the circuit will work with in a rage of voltages....
this is where you begin find differing preferances and opinions
and where you start voicing..... hook it up to a speaker
see if it works....
on your layout....... things look like they'll work ....
when you hear the amp..... you will have an chance to see how changeing
the supply voltage will affect the amps tone... the resistor between the
2nd and 3rd filter cap can be parallel'd to reduce its value temporarly
to raise the volts.....the circuit will work with in a rage of voltages....
this is where you begin find differing preferances and opinions
and where you start voicing..... hook it up to a speaker
see if it works....
lazymaryamps
Re: old thread
Hooked it up now to the Cannabis Rex that was on the kitchen table, seemed to work ok. Cant' say for the tone, sounded ratty and not very loud even when turned all the way up.
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Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: old thread
yeah......it lives
did it do anything weird..... noise hum ....smoke.... ?
it'l be hard to judge until you have a speaker in a cabinet
it a good opportunity clean up the in side and look into humm reduction
get to know the thing..... look for more issues to solve...
did it do anything weird..... noise hum ....smoke.... ?
it'l be hard to judge until you have a speaker in a cabinet
it a good opportunity clean up the in side and look into humm reduction
get to know the thing..... look for more issues to solve...
lazymaryamps
Re: old thread
I already cleaned up the wiring, when I switched it on with wires like in the picture I had massive oscillation, after rewiring everything seemed fine, I didn't hear much hum or anything special. As I've understood caps, speakers and tubes have a break-in period, how long does it take for a fresh amp to show what it really is?
Thanks to everyone for help!
Thanks to everyone for help!
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Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: old thread
you've all ready done a survey of circuit values
some will drift the longer the amp is used
take notes
it depends..... I like weeks of use
some rate hours or days
does the amp fullfill its application
some will drift the longer the amp is used
take notes
it depends..... I like weeks of use
some rate hours or days
does the amp fullfill its application
lazymaryamps
Re: old thread
Tried the amp today at a rehearsal place to a Marshall 4x12, sounded pretty good and no hum at all. 5k primary / 8 ohm was what I use, 2,5k pri / 8 ohm threw it into oscillation. Hard to really evaluate it, I need peace and quiet and my own guitar, but I think I need more gain from the pre bottle, a Tele wasn't able to put is crunchy enough when cranked up.
Re: old thread
Hey folks!
Had to lay this project on the shelf for a "while", a year strictly speaking. Now I've got the cabin ready and I must say it sound amazing to my ears... except the amp has developed some nasty habits and I don't know why.
When I have the volume all the way down or all the way up I get this squeeling sound (oscillation?), a year ago when I tried the amp it was ok with no hum or oscillation. Tried it with another output tube and makes no difference but I haven't got another 6N1P to try. I wonder if I might have damaged the tubes while shifting them and stuff or the amp itself? Or maybe some of the wires have been moving around?
Any tips?
Had to lay this project on the shelf for a "while", a year strictly speaking. Now I've got the cabin ready and I must say it sound amazing to my ears... except the amp has developed some nasty habits and I don't know why.
When I have the volume all the way down or all the way up I get this squeeling sound (oscillation?), a year ago when I tried the amp it was ok with no hum or oscillation. Tried it with another output tube and makes no difference but I haven't got another 6N1P to try. I wonder if I might have damaged the tubes while shifting them and stuff or the amp itself? Or maybe some of the wires have been moving around?
Any tips?
my amp
Hey folks!
Had to lay this project on the shelf for a "while", a year strictly speaking. Now I've got the cabin ready and I must say it sound amazing to my ears... except the amp has developed some nasty habits and I don't know why.
When I have the volume all the way down or all the way up I get this squeeling sound (oscillation?), a year ago when I tried the amp it was ok with no hum or oscillation. Tried it with another output tube and makes no difference but I haven't got another 6N1P to try. I wonder if I might have damaged the tubes while shifting them and stuff or the amp itself? Or maybe some of the wires have been moving around?
Any tips?
Had to lay this project on the shelf for a "while", a year strictly speaking. Now I've got the cabin ready and I must say it sound amazing to my ears... except the amp has developed some nasty habits and I don't know why.
When I have the volume all the way down or all the way up I get this squeeling sound (oscillation?), a year ago when I tried the amp it was ok with no hum or oscillation. Tried it with another output tube and makes no difference but I haven't got another 6N1P to try. I wonder if I might have damaged the tubes while shifting them and stuff or the amp itself? Or maybe some of the wires have been moving around?
Any tips?
Re: old thread
utervo,
Andy Le Blanc helped you a lot on this build so I will try take over.
Ceriatone 5F1 single ended amp using Hammond 125ESE multi tap OT, way more than what this amp needed.
I want to back up and find out if you used three speaker jacks 4, 8, and 16 ohm taps and the wire color to each jack.
Also, if you are having oscillation you can try reverse the main heater (filament) wires from the PT to your 6V6 tube and see if that stops the noise.
Mark
Andy Le Blanc helped you a lot on this build so I will try take over.
Ceriatone 5F1 single ended amp using Hammond 125ESE multi tap OT, way more than what this amp needed.
I want to back up and find out if you used three speaker jacks 4, 8, and 16 ohm taps and the wire color to each jack.
Also, if you are having oscillation you can try reverse the main heater (filament) wires from the PT to your 6V6 tube and see if that stops the noise.
Mark
Re: old thread
Hello Mark,
Hadn't noticed your post for over a year... I changed the preamp bottle to a new one but everything remains the same, so it's not anyone of the tubes as I have gone thru all of them.
Tried yesterday from a friends advice to add negative feedback and dropped another resistor in parallel to the 22k it has now, the amp went just completely unstable.
The most stability I have when my 8ohm speaker is connected to the white jack, which is at 8 ohm 2500 ohm primary.
When the volume is turned all the way down I get white noise and oscillation, then in the middle the hearable oscillation goes away, but you can hear something "distort" the guitar sound, not distort like in a preferable way.
The other output jacks make the amp go berserk with oscillation.
Hadn't noticed your post for over a year... I changed the preamp bottle to a new one but everything remains the same, so it's not anyone of the tubes as I have gone thru all of them.
Tried yesterday from a friends advice to add negative feedback and dropped another resistor in parallel to the 22k it has now, the amp went just completely unstable.
I have 3 ouput jacks, with white, yellow and green connected to each separate tip, then I have a wire bar across the sleeves for the black from where a wire goes to the ground star. The orange wire goes to the negative feedback resistor.M Fowler wrote:utervo,
I want to back up and find out if you used three speaker jacks 4, 8, and 16 ohm taps and the wire color to each jack.
The most stability I have when my 8ohm speaker is connected to the white jack, which is at 8 ohm 2500 ohm primary.
When the volume is turned all the way down I get white noise and oscillation, then in the middle the hearable oscillation goes away, but you can hear something "distort" the guitar sound, not distort like in a preferable way.
The other output jacks make the amp go berserk with oscillation.
Will try that next.M Fowler wrote: Also, if you are having oscillation you can try reverse the main heater (filament) wires from the PT to your 6V6 tube and see if that stops the noise.