Hi,
That's really hard for me to tell...
Here's what I would do before trying the OPT: I'd build the circuit first using very good passive components.
Once you're familiar with the circuit you could then try to replace the coupling cap with a good OPT and see if it suits your taste.
Remember that you need a gapped one as you have DC on the output.
One more thing, have you thought about the volume control for the preamp or is that taken care of already?
Just my 2 cents,
That's really hard for me to tell...
Here's what I would do before trying the OPT: I'd build the circuit first using very good passive components.
Once you're familiar with the circuit you could then try to replace the coupling cap with a good OPT and see if it suits your taste.
Remember that you need a gapped one as you have DC on the output.
One more thing, have you thought about the volume control for the preamp or is that taken care of already?
Just my 2 cents,
Hi,
The DACTs are all series attenuators, so the more you turn down the volume the more resistors you in series....
Opinion may vary on this but I hear the Goldpoint sound better and you have more choices to suit your needs.
GOLDPOINT.
If you can source ELMA rotary switches you can also build them yourself using your favourite brand of resistors, solder and choose the type of attenuator that suits you best.
The linked site has alot of info on various types.
In most cases you'll need to remove the 400K gridleak resistor as it would be in // with bottom leg of the attenuator's resistor.
Cheers,
The DACTs are all series attenuators, so the more you turn down the volume the more resistors you in series....
Opinion may vary on this but I hear the Goldpoint sound better and you have more choices to suit your needs.
GOLDPOINT.
If you can source ELMA rotary switches you can also build them yourself using your favourite brand of resistors, solder and choose the type of attenuator that suits you best.
The linked site has alot of info on various types.
In most cases you'll need to remove the 400K gridleak resistor as it would be in // with bottom leg of the attenuator's resistor.
Cheers,
To amplify Frank's point, I wouldn't get too involved with designer parts and fancy pots until you have the basics of the circuit wrung out. A $2 Radio Shack pot will not be your limiting factor until you've done a lot of probing around topology, operating points, feedback, and parts values. Then once you have a solid baseline, you can start trying all the fancy gizmos you want.
and there off...
Hey Guys,
Just placed a rather large order for all the goodies I will need for this project
I have tried to contact Gary Pimm a couple times, with luck before the holidays, but have not been able to contact him recently, any ideas??? I'll try a post at audioasylulm.
Only thing left to do is get some iron. I'm thinking of having Jack at Electraprint wind up the pieces custom. Any thoughts? He did the work on the 845 mono iron, and it was all very nice! I'm thinking shileded and potted. I like to look at iron as a long term investment, so spending a few extra here is worth it to me.
Any other thoughts......
Thanks guys.
Bryan
PS. The GF is giving me a early birthday present, a Digital Camera, so I should be able to post some pics of the adventure!
Hey Guys,
Just placed a rather large order for all the goodies I will need for this project
I have tried to contact Gary Pimm a couple times, with luck before the holidays, but have not been able to contact him recently, any ideas??? I'll try a post at audioasylulm.
Only thing left to do is get some iron. I'm thinking of having Jack at Electraprint wind up the pieces custom. Any thoughts? He did the work on the 845 mono iron, and it was all very nice! I'm thinking shileded and potted. I like to look at iron as a long term investment, so spending a few extra here is worth it to me.
Any other thoughts......
Thanks guys.
Bryan
PS. The GF is giving me a early birthday present, a Digital Camera, so I should be able to post some pics of the adventure!
thinking out loud...
Hey Guys,
So, while waiting for some pieces to arrive, I've had a few moments to think about the PS.
Firstly, if for any reason I need a few extra volts, I can simply put a cap infront of the first choke...right? What would eb the disadvantages to this?
Secondly, would it be beneficial to drive the VR tubes and the plate CCS with another CCS set at the combined current of the regulator tubes and 12b4a?
Thanks,
Bryan
Hey Guys,
So, while waiting for some pieces to arrive, I've had a few moments to think about the PS.
Firstly, if for any reason I need a few extra volts, I can simply put a cap infront of the first choke...right? What would eb the disadvantages to this?
Secondly, would it be beneficial to drive the VR tubes and the plate CCS with another CCS set at the combined current of the regulator tubes and 12b4a?
Thanks,
Bryan
This is often done. You don't need many uF to make a big voltage difference.
The disadvantage is that as the value becomes significant, the current pulses on the rectifiers do too. This somewhat spoils the advantages of a choke-input system.
I'm not sure about feeding a VR tube from a CCS. My gut feeling is that it'll reduce stability. But I'm happy to hear from others who may think differently
Hi,
True..True...
Here's the trick: add a CCS and you're winning again...Stick the VR tube stack behind it and you're winning again...Stick a CCsS on that and bingo...
This is pretty extreme though, not something I'd do on a line pre.
That's PS design pushed to the absurd, I haven't tried it though...
Cheers,
True..True...
Here's the trick: add a CCS and you're winning again...Stick the VR tube stack behind it and you're winning again...Stick a CCsS on that and bingo...
This is pretty extreme though, not something I'd do on a line pre.
That's PS design pushed to the absurd, I haven't tried it though...
Cheers,
....so then
You guys think it would be best to keep the LCLC-VR-CCS-PLATE as originally intended vs. the LCLC-CCS-VR-CCS? (I really need some schematic software drafting program to make this easier to describe)
I guess it would be a bit much. Just thought I'd throw the idea out there anyway!
Bryan
You guys think it would be best to keep the LCLC-VR-CCS-PLATE as originally intended vs. the LCLC-CCS-VR-CCS? (I really need some schematic software drafting program to make this easier to describe)
I guess it would be a bit much. Just thought I'd throw the idea out there anyway!
Bryan
If one were to set up the PS this way, I assume you would configure the first CCS to provide the amount of current to supply the plate and VR tubes.
That is if the 12B4A has 30mA through it, and the VR tubes aer regulating at 20mA, the first CCS is set to 50mA.
What woud the benefits of this configuration be in terms of sonics, if any?
Thanks,
Bryan
That is if the 12B4A has 30mA through it, and the VR tubes aer regulating at 20mA, the first CCS is set to 50mA.
What woud the benefits of this configuration be in terms of sonics, if any?
Thanks,
Bryan
Hi Bryan,
Looks like we're chasing the same idea. I've just got the parts for a CLCLCLC-CCS-VR-CCS supply for my phono/line stage. At this point, only the line stage will see the final CCS(Bottlehead C4S). The first CCS is an IXYS IXCP10M45S ccs on a chip(hope they ain't lying about it's specs). The first Cap in the filter is just big enough to bring up the voltage for the VR tubes.
Pete
Looks like we're chasing the same idea. I've just got the parts for a CLCLCLC-CCS-VR-CCS supply for my phono/line stage. At this point, only the line stage will see the final CCS(Bottlehead C4S). The first CCS is an IXYS IXCP10M45S ccs on a chip(hope they ain't lying about it's specs). The first Cap in the filter is just big enough to bring up the voltage for the VR tubes.
Pete
Hi all,
Thought I would toss out some comments as I have built several systems with ccs fed shunt reg supplies.
The latest line stage to get the treatment is the 85 line stage. In it's previous setup the supply was a simple LC supply feeding the plate supply CCS. The L was a Hammond 156C 150Hy choke and the C was a Solen 20uf metalized polypropylene. There were seperate chokes and caps for each channel.
The new supply setup is CLC with the C's being 3uf paper in oils and the L is 15Hy. This feeds into a battery biased CCS set to 32ma feeding a stack of VR tubes to create a 400V regulated supply.
The 400 volt supply feeds a pair of hybrid pentode/mosfet CCS's that are the plate loads for the 85's. The 85's are running at 6ma with 250 volts on the plate. At this operating point the line stage is capable of over 300 volts P-P output without breaking a sweat. Nothing like having a little headroom...
The ccs fed shunt reg supply makes a nice improvement to the sound. It is kind of like the frosting on the cake. The music just sounds more real.
I helped a friend install a ccs fed shunt reg in his line stage that was already setup with ccs's on the triodes. He keeps raving about what a nice improvement it was.
Somewhere around here I have notes from the late John Camile's presentation from one of the early VSAC's. His notes showed that the CCS-VR-CCS arrangement was capable of power supply noise rejection of over 150dB.
Here is the schematic for the 85 line stage. With minor changes it can be used with most of the tubes commonly used for line stages and with higher current tubes in the 15-30ma range, it makes a nice driver stage.
Thought I would toss out some comments as I have built several systems with ccs fed shunt reg supplies.
The latest line stage to get the treatment is the 85 line stage. In it's previous setup the supply was a simple LC supply feeding the plate supply CCS. The L was a Hammond 156C 150Hy choke and the C was a Solen 20uf metalized polypropylene. There were seperate chokes and caps for each channel.
The new supply setup is CLC with the C's being 3uf paper in oils and the L is 15Hy. This feeds into a battery biased CCS set to 32ma feeding a stack of VR tubes to create a 400V regulated supply.
The 400 volt supply feeds a pair of hybrid pentode/mosfet CCS's that are the plate loads for the 85's. The 85's are running at 6ma with 250 volts on the plate. At this operating point the line stage is capable of over 300 volts P-P output without breaking a sweat. Nothing like having a little headroom...
The ccs fed shunt reg supply makes a nice improvement to the sound. It is kind of like the frosting on the cake. The music just sounds more real.
I helped a friend install a ccs fed shunt reg in his line stage that was already setup with ccs's on the triodes. He keeps raving about what a nice improvement it was.
Somewhere around here I have notes from the late John Camile's presentation from one of the early VSAC's. His notes showed that the CCS-VR-CCS arrangement was capable of power supply noise rejection of over 150dB.
Here is the schematic for the 85 line stage. With minor changes it can be used with most of the tubes commonly used for line stages and with higher current tubes in the 15-30ma range, it makes a nice driver stage.
An externally hosted image should be here but it was not working when we last tested it.
Thanks Gary and all your CCS stuffs. I have a voltage question. I am working on a 813PP and need some pretty high voltage. The power transformers can deliver 1400VDC, with choke input filtering, I am going to get about 1260VDC for the B+, will your CCS be able to handle the high B+?
I read somewhere that, on the pentode version of the CCS, the actual CCS only see about 1% of the actual voltage, but I am not sure what does "actual voltage" really mean: do I have to specify all the capacitors to be able to handle 1200V or the capacitor voltage rating per the CCS (say V5) is adequate?
I assume that the pentode (within the pentode CCS) needs to be able to handle the B+ itself, so I assume that I will need something like a 813 to build this high B+ CCS.
I read somewhere that, on the pentode version of the CCS, the actual CCS only see about 1% of the actual voltage, but I am not sure what does "actual voltage" really mean: do I have to specify all the capacitors to be able to handle 1200V or the capacitor voltage rating per the CCS (say V5) is adequate?
I assume that the pentode (within the pentode CCS) needs to be able to handle the B+ itself, so I assume that I will need something like a 813 to build this high B+ CCS.
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