Yep
Steve's old valves take some beating.
Should be an interesting project.
Rocky - The Quatroquel
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Cressy Snr
- Amstrad Tower of Power
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#151
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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little eddy
- Old Hand
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#152
Well I have something for Owston.
The DC heater boards are both giving out 3.9V which I guess is close enough.
Cathode voltages are 7.25 and 7.5 so just about where I'd planned @ 20.1 and 20.8mA respectively. Va is a health 185V so again almost bang on where I'd aimed.
A little edgy when first switched on but quite a substantial bass. Needs a few hours playing in but sounding positive.
After a few hours I may try the pair old older 41MPs I've acquired.
Phew!
The DC heater boards are both giving out 3.9V which I guess is close enough.
Cathode voltages are 7.25 and 7.5 so just about where I'd planned @ 20.1 and 20.8mA respectively. Va is a health 185V so again almost bang on where I'd aimed.
A little edgy when first switched on but quite a substantial bass. Needs a few hours playing in but sounding positive.
After a few hours I may try the pair old older 41MPs I've acquired.
Phew!
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Last edited by little eddy on Fri Oct 03, 2014 6:56 pm, edited 1 time in total.
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.
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IslandPink
- Amstrad Tower of Power
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#154
Thats good news mike, the old pair will need a little time on them too but there is a subtle difference between them
Be good to hear...
Be good to hear...
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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little eddy
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#155
So not too bad at Owston although I thought a little sibilance when playing the Elbow track. Maybe the recording is on the edge, lack of burning-in or perhaps it wasn't helped by the solid sate CCS?
Anyway on to the next iteration or two.
Luckily picked up a pair of Sowter 9525 inter stage transformers so they are my first mod. I was going to feed them via a simple 2 stage RCRC buffer string. But with all of the talk on the day about separate power supplies, I'd like to investigate what can be done in terms of maximising the isolation of the 41MP amplifier stage. Discussed this with Nick and he's suggested a shunt voltage regulator fed via a CSS.
So my question is: While I'm deliberating on the voltage regulator circuit, can I simply replace one of the buffer resistors with my existing 10M45s CCSs as per the attached. Would this make sense as an interim measure as I could then simply insert the shunt regulator and adjust the CCS accordingly.
Anyway on to the next iteration or two.
Luckily picked up a pair of Sowter 9525 inter stage transformers so they are my first mod. I was going to feed them via a simple 2 stage RCRC buffer string. But with all of the talk on the day about separate power supplies, I'd like to investigate what can be done in terms of maximising the isolation of the 41MP amplifier stage. Discussed this with Nick and he's suggested a shunt voltage regulator fed via a CSS.
So my question is: While I'm deliberating on the voltage regulator circuit, can I simply replace one of the buffer resistors with my existing 10M45s CCSs as per the attached. Would this make sense as an interim measure as I could then simply insert the shunt regulator and adjust the CCS accordingly.
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TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.
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pre65
- Amstrad Tower of Power
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#156
I use an Ixys 10M45s as the anode load on my GK-71 amp driver, sort of isolates the driver stage from the PSU. Seems to work well.
On your amp, if the current is constant (CCS) and the voltage is regulated (shunt) how will that work ?
On your amp, if the current is constant (CCS) and the voltage is regulated (shunt) how will that work ?
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)
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little eddy
- Old Hand
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#157
Ultimately was looking to do something similar to the K&K high voltage shunt regulator kit: http://www.kandkaudio.com/accessories.html
Also looking at the Gary Pimm site, this looks a similar general approach to some of his amps with current source feeding a voltage regulator.
The 20mA 10M45s CCS is already in circuit so thought might just leave it there even though I will be using the inter stage transformer as the anode load. Just propose to move my last 1uF film buffer cap from the input to the output of the CCS.
Also looking at the Gary Pimm site, this looks a similar general approach to some of his amps with current source feeding a voltage regulator.
The 20mA 10M45s CCS is already in circuit so thought might just leave it there even though I will be using the inter stage transformer as the anode load. Just propose to move my last 1uF film buffer cap from the input to the output of the CCS.
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.