Shoog said:
Predictably, i can only agree. For reasons i don't pretend to understand semiconductor hash sounds quite unpleasant superimposed upon a nice tube circuit.
CJ's solution to low ripple with low capacitance is understandable on engineering grounds but a really bad compromise soundwise.
And these cascaded regulators
I guess a couple of nice chokes are just too expensive for most commercial amps.
Hi Shoog,
If you study older test equipment (not just by looking at schematics, but by actually poking around inside of them) you will be amazed at how well their designs worked. I think we could learn a lot from those engineers if we only would look at their work. They really did know what they were doing. These days people tend to simply throw parts at a problem without considering what they are trying to achieve.
My goal would be to not generate problems that have to be solved later. Consider that this noise may be blocked with a choke, but will appear in other windings. I like using AC for heaters biased up about 30 VDC from ground. This avoids wasting power in the heater circuit, never mind even heavier spikes.
-Chris
It can be if designed properly. However, I find it's easier to simply design using properly sized components. If I wanted a very quiet supply, I might use an L-C-L-C type. The capacitors may be on the order of 10 ~ 20 uF (that's plenty!). Given a choice, I'd follow this up with a voltage regulator.
If you study older test equipment (not just by looking at schematics, but by actually poking around inside of them) you will be amazed at how well their designs worked. I think we could learn a lot from those engineers if we only would look at their work. They really did know what they were doing. These days people tend to simply throw parts at a problem without considering what they are trying to achieve.
Yes.
My goal would be to not generate problems that have to be solved later. Consider that this noise may be blocked with a choke, but will appear in other windings. I like using AC for heaters biased up about 30 VDC from ground. This avoids wasting power in the heater circuit, never mind even heavier spikes.
-Chris
Hi analog_sa,
Anything that adds shipping weight will be avoided in a modern design unless the advertising guys can get enough mileage out of their use. The engineering guys probably want them.
-Chris
Anything that adds shipping weight will be avoided in a modern design unless the advertising guys can get enough mileage out of their use. The engineering guys probably want them.
I fully agree! Terrible mistake in my book.
-Chris
analog_sa said:
12B4 have developed shunt power ; even custom made power xformer became sorta standard one.
none- I say none of mentioned preamps ,can't have that immediacy as plain dreky anode stage with decent supply;
point is in enough potent tube to achieve this ,along with adequate PSU .
for my liking- ideal 12B4 preamp from that thread will be used with choke load ; that's certainly,even if costlier and somewhat harder to make proper, elegant way to have maximized dynamic capabilities of so simple topology ;
analog_sa said:
now you got me...........
point is .......... I have favorite topologies .......but I also have bad habit to leave freedom to other ppl to also have their faves
😀
hehe- that's their loss....not mine
Definately.
None of my circuits use DC on the heaters (apart from Thorstens phono preamp). Its simply not needed. I built a 5687 preamp which hummed terribly, I went DC on the heaters and the hum went away. I rebuilt it with anode stoppers and AC heaters- and guess what no hum.
Find the source of the problem and solve it. A sledge hammer can flatten out a problem - but its still there doing its nasties.
Shoog
Having been through several 12AU7 topologies, I have gathered that this type sounds better in a cascade like in PV12.
Also a passively multichoke filtered with small poly 1st cap tube rectified psu, sounded seriously better both on 12AU7 cascade, 6SN7 SRPP and 6v6G triode made grounded cathode, VS a tube rectified and regulated (12B4 as pass element) psu.
12AU7 has several NOS flavors that promote happy rolling. I have seen many people liking the particular 12AU7 family non linearity.
5687 and 12B4 have an immediacy that is gripping but sometimes they can get caught out as cold sounding. A bit like Audio Research sound. In esoteric 300B SE amps, some diyers deleted 5687 drivers, after testing a good old 6SN7 cascade. Also current sourcing can sound tense. Only choke plate loading does the job properly and increases dynamics without introducing constipation to my ears.
CJ equipment have obviously some psu solutions that are choices of commercial manufacturing engineering, cost and marketing. Only nicely judged.
Also a passively multichoke filtered with small poly 1st cap tube rectified psu, sounded seriously better both on 12AU7 cascade, 6SN7 SRPP and 6v6G triode made grounded cathode, VS a tube rectified and regulated (12B4 as pass element) psu.
12AU7 has several NOS flavors that promote happy rolling. I have seen many people liking the particular 12AU7 family non linearity.
5687 and 12B4 have an immediacy that is gripping but sometimes they can get caught out as cold sounding. A bit like Audio Research sound. In esoteric 300B SE amps, some diyers deleted 5687 drivers, after testing a good old 6SN7 cascade. Also current sourcing can sound tense. Only choke plate loading does the job properly and increases dynamics without introducing constipation to my ears.
CJ equipment have obviously some psu solutions that are choices of commercial manufacturing engineering, cost and marketing. Only nicely judged.
Re: current is not necessary constant in class a operation
Eric,
Huh?
Unless you are talking about miniscule variations or driving some high amplitudes (actually going to power), not according to my theory and experience. My usual case was outputting up to say 20Vpp (mostly much less), with a supply of some 300V, and often using a cathode follower for low output impedance. With that I really did not get any mentionable current variation on the h.t. line.
What am I overlooking?
Regards
Eric Juaneda said:
Eric,
Huh?
Unless you are talking about miniscule variations or driving some high amplitudes (actually going to power), not according to my theory and experience. My usual case was outputting up to say 20Vpp (mostly much less), with a supply of some 300V, and often using a cathode follower for low output impedance. With that I really did not get any mentionable current variation on the h.t. line.
What am I overlooking?
Regards
About Conrad Johnson evolution, the 'Premier Ten' preamplifier use 6GK5 tube, no phono stage, 2x 30uF filering capacitors and a lot of special polystyrene capacitors (white components on the picture).
you could find schematic diagram on analogstereo.com
This very nice preamplifier use serial regulator for each channel. PV12 seem to use one regulator for both channels. I could listen to 'Premier Ten' in 1999. Very nice sound.
Eric
you could find schematic diagram on analogstereo.com
This very nice preamplifier use serial regulator for each channel. PV12 seem to use one regulator for both channels. I could listen to 'Premier Ten' in 1999. Very nice sound.
Eric
Attachments
Hi Johan,
I take my calculator to evaluate DC and AC current in linear stage.
Dc current for first 12AT7 is approximatively 1.9mA, 4mA for the second one. Alternative current
for 1Vpp output in 20K Ohm load (input impedance of your transistor amplifier) is near 74uA.
--> 1.27% current variation. Effectively not so far.
With your 20Vpp output, current variation is 1.5mA.
--> 25% current variation. Wahou !
Listening power supply
With feedback free stage, every variations on power supply flow directly on the output. It is interesting to listen it. For this try, I plug CD only on left channel preamplifier, turn sound control at maximum, use capacitor (10uF) to link regulated power supply to left channel input and send to the amplifier only left channel output. (see picture)
After this try, you understand that using regulator for each channel could enhance sounding.
The Conrad Johnson 'Premier Ten' preamplifier does it.
Eric
I take my calculator to evaluate DC and AC current in linear stage.
Dc current for first 12AT7 is approximatively 1.9mA, 4mA for the second one. Alternative current
for 1Vpp output in 20K Ohm load (input impedance of your transistor amplifier) is near 74uA.
--> 1.27% current variation. Effectively not so far.
With your 20Vpp output, current variation is 1.5mA.
--> 25% current variation. Wahou !
Listening power supply
With feedback free stage, every variations on power supply flow directly on the output. It is interesting to listen it. For this try, I plug CD only on left channel preamplifier, turn sound control at maximum, use capacitor (10uF) to link regulated power supply to left channel input and send to the amplifier only left channel output. (see picture)
After this try, you understand that using regulator for each channel could enhance sounding.
The Conrad Johnson 'Premier Ten' preamplifier does it.
Eric
Attachments
Hi Eric,
It's always wise to listen to your power supply. Especially under load, both reasonable and on the outside of normal operation.
-Chris
It's always wise to listen to your power supply. Especially under load, both reasonable and on the outside of normal operation.
-Chris
I'm very very confused.... I don't know what to do ???
Make the PV-12, or Premier Ten is a good idea???
Or maybe the more simple 12B4 preamp ???
I'm looking to a lot of schematic since a couple of days... but I have to choose if I want to begin !!!!!
Make the PV-12, or Premier Ten is a good idea???
Or maybe the more simple 12B4 preamp ???
I'm looking to a lot of schematic since a couple of days... but I have to choose if I want to begin !!!!!
Eric,
Then our experiences are different.....
But thanks for your reply; I accept what you honestly found in your case.
Regards.
Then our experiences are different.....
But thanks for your reply; I accept what you honestly found in your case.
Regards.
Hi, arold19,
I think it's important that you simply build the preamp you think sounds good. You've heard them and they do sound good. Much better than most.
So don't agonize over the choice, build it and be happy. You will have done more than many who only talk. Tell us about your journey and ask for help if you feel you want suggestions on your build.
-Chris
I think it's important that you simply build the preamp you think sounds good. You've heard them and they do sound good. Much better than most.
So don't agonize over the choice, build it and be happy. You will have done more than many who only talk. Tell us about your journey and ask for help if you feel you want suggestions on your build.
-Chris
I don't very understand why there no electrolytic capacitor in the PV-12 power supply ????
It use only 2 * 20uF polypropylene capacitor, can someone explan me why ??
Maybe because it is regulate.....
Thank you !
It use only 2 * 20uF polypropylene capacitor, can someone explan me why ??
Maybe because it is regulate.....
Thank you !
Hi arold19,
2 X 20 uF is generous. They honestly do not require more capacitance and high capacitance values can work against you. They are using good engineering instead of following popular fads.
Regulation allows them to achieve a very low noise power supply. They could have used more of these expensive capacitors and some expensive chokes to achieve the same end, but at a higher cost. Proper engineering allows them to manufacture a higher grade product at a minimum cost for the product. Whether the sound of CJ is liked or not is another question all together. I think they sound good and they are also engineered well. You could choose inferior circuits to build, at lease these sound good and don't tend to cost a lot to maintain.
-Chris
They use polypropylene capacitors instead of electrolytic caps for their superior high frequency performance.
These types work better than other types of capacitors.
2 X 20 uF is generous. They honestly do not require more capacitance and high capacitance values can work against you. They are using good engineering instead of following popular fads.
Regulation allows them to achieve a very low noise power supply. They could have used more of these expensive capacitors and some expensive chokes to achieve the same end, but at a higher cost. Proper engineering allows them to manufacture a higher grade product at a minimum cost for the product. Whether the sound of CJ is liked or not is another question all together. I think they sound good and they are also engineered well. You could choose inferior circuits to build, at lease these sound good and don't tend to cost a lot to maintain.
-Chris
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