A 2 or 3-channel SE 'Horn-amp'
- pre65
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#61
I used 6S4s and 6B4-g on one amp I had with IO (International octal) sockets with no problems.
See Mike H tip in previous post.
See Mike H tip in previous post.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
- IslandPink
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#62
OK, following-up on Mike's advice, I have 6.2V DC to the valve that is supplied by the 'Thorsten' supply . It is glowing very slightly when the lights are off. Pretty surprising really , would have expected more glow .
The other one ( supplied by a Lehane V-reg supply ) is showing 4.6V DC .
This is odd because this supply could happily light a 6N6P at 0.75A from a 7V AC input from a toroid . I guess it's dropped-out of regulation.
I have no more energy this evening to do anything .
Project is now touch & go for the weekend, it will be a monumental ball-ache to take this supply out and fit something else ...
Thanks for the help .
The other one ( supplied by a Lehane V-reg supply ) is showing 4.6V DC .
This is odd because this supply could happily light a 6N6P at 0.75A from a 7V AC input from a toroid . I guess it's dropped-out of regulation.
I have no more energy this evening to do anything .
Project is now touch & go for the weekend, it will be a monumental ball-ache to take this supply out and fit something else ...
Thanks for the help .
"Once you find out ... the Circumstances ; then you can go out"
- IslandPink
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#63
Andrew -
There's still a healthy 7.2V AC going into the supply .
Is the voltage-out and the resistors ( 560 + 56 nominal ) used to set that voltage, dependant on the current-out ?
Is there some mileage in raising the resistance in that location ?
I wish I'd put a pot in there now
There's still a healthy 7.2V AC going into the supply .
Is the voltage-out and the resistors ( 560 + 56 nominal ) used to set that voltage, dependant on the current-out ?
Is there some mileage in raising the resistance in that location ?
I wish I'd put a pot in there now
"Once you find out ... the Circumstances ; then you can go out"
- Mike H
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#64
This is the trouble with filament regs, getting them to work
6C4C is 1 Amp isn't it, so is 6B4G the same?
But that is the hot current of course, cold filament resistance is <= 1 tenth what it is hot.
6C4C is 1 Amp isn't it, so is 6B4G the same?
But that is the hot current of course, cold filament resistance is <= 1 tenth what it is hot.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- IslandPink
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#65
Yes, most frustrating, Mike.
But this supply does work , has been checked at 0.75A .
The 6N6P ( used before ) and the 6B4G are both oxide-coated filaments, so the cold resistance should not be too much different .
The 6B4G is also 1 amp, same as 6C4C , yes .
But this supply does work , has been checked at 0.75A .
The 6N6P ( used before ) and the 6B4G are both oxide-coated filaments, so the cold resistance should not be too much different .
The 6B4G is also 1 amp, same as 6C4C , yes .
"Once you find out ... the Circumstances ; then you can go out"
#66
So to recap, you have a Vreg with 7V AC RMS in trying to supply 6.3v DC?
If that is the case I think you need a 9VAC RMS in, just from memory 6.3v DC from 6.3v-ish AC (even 7v AC) is hard to achieve even with a simple 3 legged reg let alone a double reg like the Vreg as there's two regulation voltages dropped.
I can bring a bench supply down to Owston if it helps or a 9V TX.
Andrew
If that is the case I think you need a 9VAC RMS in, just from memory 6.3v DC from 6.3v-ish AC (even 7v AC) is hard to achieve even with a simple 3 legged reg let alone a double reg like the Vreg as there's two regulation voltages dropped.
I can bring a bench supply down to Owston if it helps or a 9V TX.
Andrew
Analogue, the lost world that lies between 0 and 1.
- Mike H
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#67
0.75A is not the same aa 1A.
I agree with Andrew, what I found is you need enough 'overhead' to run the reg chip(s). LM317 needs 3V minimum across it I think. For example.
So that would be 9.3V minimum on the input side for 6.3V out. If it were a LM317.
I agree with Andrew, what I found is you need enough 'overhead' to run the reg chip(s). LM317 needs 3V minimum across it I think. For example.
So that would be 9.3V minimum on the input side for 6.3V out. If it were a LM317.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- IslandPink
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#68
Thanks Andrew
7.2V AC-in actually , if that makes any difference
It would help if you put together a simple table for us to refer to ... ( as requested... )
Just had a blinding light of realisation-
AC heating
It is a 700Hz to 20k channel, after all !!
7.2V AC-in actually , if that makes any difference
It would help if you put together a simple table for us to refer to ... ( as requested... )
Just had a blinding light of realisation-
AC heating
It is a 700Hz to 20k channel, after all !!
"Once you find out ... the Circumstances ; then you can go out"
#70
I'll bring a 9v TX if you want to provide somewhere to hook up to on the amp, you may get intermod even higher up teh spectrum with the 50Hz so DC will be better.IslandPink wrote:Thanks Andrew
7.2V AC-in actually , if that makes any difference
It would help if you put together a simple table for us to refer to ... ( as requested... )
Just had a blinding light of realisation-
AC heating
It is a 700Hz to 20k channel, after all !!
So far I have been asked for 5v, 6.3v and 12.6v, the first two both require a 9v TX.
Andrew
Analogue, the lost world that lies between 0 and 1.
- IslandPink
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#71
Ok, thanks.
I will see how it sounds tomorrow .
Fingers crossed the rest of the amp works , he he
Solid-state eh ? - it would steal your face if it had the chance ...
I will see how it sounds tomorrow .
Fingers crossed the rest of the amp works , he he
Solid-state eh ? - it would steal your face if it had the chance ...
"Once you find out ... the Circumstances ; then you can go out"
- Mike H
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#72
OK 7.2VAC in, you'd think you get 1.414 x = DC, but no, the current load is so large that it pulls it down to nearly the AC level. And the ripple is large.... guess how I know ...
UNLESS you have a transformer that is over-spec on the current (say double), then it will hold it up better. It's all about winding resistance I think.
UNLESS you have a transformer that is over-spec on the current (say double), then it will hold it up better. It's all about winding resistance I think.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- IslandPink
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#73
Yes, I'm always too optimistic about power supply voltages .
Meanwhile - there's quite a lot of 'stuff' in this amp, all of a sudden :
Meanwhile - there's quite a lot of 'stuff' in this amp, all of a sudden :
"Once you find out ... the Circumstances ; then you can go out"
- IslandPink
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#74
Filament voltages all OK now. AC on the upper 6B4G.
HT voltages all near-enough correct .
166V on 4P1L anode perhaps a little low - could change cathode R from 110R to 120R tomorrow .
All hooked-up and playing now . Sounds better listening in the hall than in the front room Ouch ! No shortage of gain, anyway !
Upper 6B4G fil AC is tied to cathode resistor on one side , so that isn't very good ! - must do a virtual centre-tap tomorrow , as there's a lot of 100Hz etc coming out of the Azurahorn - probably making the upper mids etc. sound a bit aggressive .
Now for a bit of Ginger Baker to run things in ....
HT voltages all near-enough correct .
166V on 4P1L anode perhaps a little low - could change cathode R from 110R to 120R tomorrow .
All hooked-up and playing now . Sounds better listening in the hall than in the front room Ouch ! No shortage of gain, anyway !
Upper 6B4G fil AC is tied to cathode resistor on one side , so that isn't very good ! - must do a virtual centre-tap tomorrow , as there's a lot of 100Hz etc coming out of the Azurahorn - probably making the upper mids etc. sound a bit aggressive .
Now for a bit of Ginger Baker to run things in ....
"Once you find out ... the Circumstances ; then you can go out"
- IslandPink
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#75
The sound is getting better but I will have to get rid of the hum a.s.a.p. tomorrow morning !
See pic -
See pic -
"Once you find out ... the Circumstances ; then you can go out"