Revisiting some "old" ideas from 1970's - IPS, OPS

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thimios

Member
Joined 2009
jwilhelm said:
You're getting closer! You're making more progress than I am.
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vzaichenko said:
Thimios, it gives me association with a tank (in a good way) - a combination of power and uncompromised durability :cool:
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Jeff don't forget,it is one channel!
I hope to do the same with the other.:D

Valery,yes like a tank ,the housing and the internall;)
 
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T

thimios

Member
Joined 2009
pinnocchio said:
The NS OPS has been singing in my listening room for a few hours last night but on test speakers and it sounded really good with great soundstage. I have to re-bias the output stage since I'm getting a 5 Celsius difference on the heatsinks.

Do
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Good news DO!
Let's see what we have here.:cool:
TubeSumo on the road!
 

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pinnocchio

pinnocchio

Member
Joined 2010
quebecdiy.forumactif.com/
jwilhelm said:
Did you get your issues with the over-current detection ironed out? These amps don't make a lot of heat so any air movement in the room such as a register can cause a large difference in heat sink temperatures.
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I tested the amplifier with a 2R load with a music source and medium to high volume and the protection was far from being close to trip... I haven’t tested the amplifier on the main speakers yet, from where it was tripping the protection. I will test this further. There is only one register in that room and it is far back but I will block it and let the amp run for a couple hours.

thimios said:
Good news DO!
Let's see what we have here.:cool:
TubeSumo on the road!
Click to expand...

Nice! Mine is all assembled but not yet tested since I have to assemble the filament supply for it. You’ll probably get there first!

Ciao!
Do
 
T

thimios

Member
Joined 2009
pinnocchio said:
I tested the amplifier with a 2R load with a music source and medium to high volume and the protection was far from being close to trip... I haven’t tested the amplifier on the main speakers yet, from where it was tripping the protection. I will test this further. There is only one register in that room and it is far back but I will block it and let the amp run for a couple hours.



Nice! Mine is all assembled but not yet tested since I have to assemble the filament supply for it. You’ll probably get there first!

Ciao!
Do
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If you have already IPS assembled why you not use a bench power supply for tube filament?;)
 
pinnocchio

pinnocchio

Member
Joined 2010
quebecdiy.forumactif.com/
thimios said:
If you have already IPS assembled why you not use a bench power supply for tube filament?;)
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I could but I'm still testing the amplifier and making sure everything is 100% ok before I go any further. I know I'm on the slow side these days but I've been working on three amps at the same time (fixing two defective FC-100 and TGM8, assembling USSA3), plus this one. :D
 
pinnocchio

pinnocchio

Member
Joined 2010
quebecdiy.forumactif.com/
ok... So here's the reason why my left channel heatsink is 5 degrees colder... The emitter resistor show no voltage across them... Previously it was biased at 20mV but for some odd reason, nothing anymore...

I've tried centering R43 and maxing R31 and redoing the whole biasing but R31 from one end to the other doesn't make bias setting go up... Only when I have R43 to max value does it give me 5mV on emitter 0.22R... Adjusting R31 when R43 is maxed doesn't change anything... I don't know what could have gone wrong but weird... Blue LEDs still light up and music still plays fine though (only tried playing at very low level)

Any pointers?

Thanks
Do
 
F

filenet

Member
Joined 2013
pinnocchio said:
ok... So here's the reason why my left channel heatsink is 5 degrees colder... The emitter resistor show no voltage across them... Previously it was biased at 20mV but for some odd reason, nothing anymore...

I've tried centering R43 and maxing R31 and redoing the whole biasing but R31 from one end to the other doesn't make bias setting go up... Only when I have R43 to max value does it give me 5mV on emitter 0.22R... Adjusting R31 when R43 is maxed doesn't change anything... I don't know what could have gone wrong but weird... Blue LEDs still light up and music still plays fine though (only tried playing at very low level)

Any pointers?

Thanks
Do
Click to expand...

Check VAS current.
 
J

jwilhelm

Member
Joined 2014
vzaudio.com/
pinnocchio said:
ok... So here's the reason why my left channel heatsink is 5 degrees colder... The emitter resistor show no voltage across them... Previously it was biased at 20mV but for some odd reason, nothing anymore...

I've tried centering R43 and maxing R31 and redoing the whole biasing but R31 from one end to the other doesn't make bias setting go up... Only when I have R43 to max value does it give me 5mV on emitter 0.22R... Adjusting R31 when R43 is maxed doesn't change anything... I don't know what could have gone wrong but weird... Blue LEDs still light up and music still plays fine though (only tried playing at very low level)

Any pointers?

Thanks
Do
Click to expand...
As George recommends, check your VAS current of the input. This is what drives the bias spreader.
 
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