Hi,
Yup..., too big to be useful...not small enough to be unobtrusive...
The 150H chokes are out...7mA won't cut it....let's put them aside for something else.
Either way, don't worry,..
Not in my pocket, no....you know, when I was toying around with tubes, chokes were hard to come by...
Too young to die, too old to rock'n roll?
Give me an idea of where you want these chokes and it can all be calculated, add the tube regs and it will kick all commercial efforts out of the window....
Cheers,
Yup..., too big to be useful...not small enough to be unobtrusive...
The 150H chokes are out...7mA won't cut it....let's put them aside for something else.
Either way, don't worry,..
Not in my pocket, no....you know, when I was toying around with tubes, chokes were hard to come by...
Too young to die, too old to rock'n roll?
Give me an idea of where you want these chokes and it can all be calculated, add the tube regs and it will kick all commercial efforts out of the window....
Cheers,
Hi,
They shouldn't be hard to find. No one else is using them commercially I think.
AES in Tampa Arizona sells them at 4.95$ a pop.
Ask for the same brand, you'll only need a pair + some spares, they'll last a lifetime anyway...
ECL85/805/6GV8
Not unless I'd redesign the whole shebang to take something like an ECL82/6BM8...
Oooops...
Rest assured I didn't have your designs in mind, Steve.
I'm sure you know what I meant.
Joe,
What are the specs of the 30H chokes you're getting?
DCR, current capability, are these PSU chokes?
Cheers,
They shouldn't be hard to find. No one else is using them commercially I think.
AES in Tampa Arizona sells them at 4.95$ a pop.
Ask for the same brand, you'll only need a pair + some spares, they'll last a lifetime anyway...
ECL85/805/6GV8
Not unless I'd redesign the whole shebang to take something like an ECL82/6BM8...
Oooops...
Rest assured I didn't have your designs in mind, Steve.
I'm sure you know what I meant.
Joe,
What are the specs of the 30H chokes you're getting?
DCR, current capability, are these PSU chokes?
Cheers,
How about this (leaving out the nuances of grid stoppers, etc.)? It loses two coupling caps. But it may have other problems that I don't yet understand.
Gain is 10. Zo should be less than 500ohms.
Here is a constant current draw version. Its gain is a little higher, about 15. Idle current on the follower is around 4mA, but if you don't need to deliver 7mA into the load, this will work. And, you won't need a regulated supply because the current draw will vary by less than 10uA or so on each channel.
However, I cannot speak for audio characteristics that other, better designers might be aware of here. Nearly as I can tell though, the freqency response will be very flat from 1Hz up above 100Khz and the distortion, on paper, should be near .0x%. less for the first one than the second.
Gain is 10. Zo should be less than 500ohms.
An externally hosted image should be here but it was not working when we last tested it.
Here is a constant current draw version. Its gain is a little higher, about 15. Idle current on the follower is around 4mA, but if you don't need to deliver 7mA into the load, this will work. And, you won't need a regulated supply because the current draw will vary by less than 10uA or so on each channel.
An externally hosted image should be here but it was not working when we last tested it.
However, I cannot speak for audio characteristics that other, better designers might be aware of here. Nearly as I can tell though, the freqency response will be very flat from 1Hz up above 100Khz and the distortion, on paper, should be near .0x%. less for the first one than the second.
Hi,
Doing away with the first coupling cap is not recommended as volpots don't like DC on their wiper.
If you use a stepped attenuator it would work fine.
The reason a voltage regulator for the linestage was included wasn't mainly for regulating, let's face it with a few hundreds of µF behind it probably never will have to.
So why use it, you may ask? It does help isolate the actual audio stage from the mains as it acts as a buffer between the two and keeping carefully designed audiostage at the desired operating points can't be a bad thing.
I quite like the designs you presented and both should benefit from the added regs.
I didn't do any math on them assuming you used a simulator, right?
Using a tube rectifier and CLC filter can only make things better still.
Cheers,
Doing away with the first coupling cap is not recommended as volpots don't like DC on their wiper.
If you use a stepped attenuator it would work fine.
The reason a voltage regulator for the linestage was included wasn't mainly for regulating, let's face it with a few hundreds of µF behind it probably never will have to.
So why use it, you may ask? It does help isolate the actual audio stage from the mains as it acts as a buffer between the two and keeping carefully designed audiostage at the desired operating points can't be a bad thing.
I quite like the designs you presented and both should benefit from the added regs.
I didn't do any math on them assuming you used a simulator, right?
Using a tube rectifier and CLC filter can only make things better still.
Cheers,
I don't think that there should be any dc on the wiper since the input grid should be at ground. If it were me, I'd eliminate both coupling caps
and use an additional grid bias resistor of 100K or so. Unless there will be DC on the output of the source.Yes, I see. I like the idea of a voltage regulator too, but I think in this case you'd mostly be regulating against line variations. As you say a big cap on the output of the PS should do the trick with respect to load variations. I might try this first before a regulator. Brett, I know you've answered this a million times, but why would the ccs shunt regulator help so much?
Burnedfingers, if you prefer these new ideas, you can make the first one be closer to constant current simply by making the cathode resistor on the follower 47k. The idle current in this stage will be closer to 4mA, but how much current do you need to put into a power amp with an input impedance of 100K?
I did use a simulator (PSpice) after thinking a bit about what might be easier to do. I have a good model for a 6SN7 which I assume is close enough to the 5692.
This makes the most sense to me. I'm working on a preamp right now and it most certainly has a tube rectifier (two in fact).
Hi,
Brett-San,
If we to throw more money at it, yes an LCLC is the better filter.
With the valved regulator in place it would be overkill in this instance, YMMV.
Regarding the CCS, the only ones I find sonically unobtrusive are the one by master Gary Pimm.
Anything else qualifies as hybrid to my ears....I have a gut feeling you might agree...
Runeight,
No, it isn't.
That resistor won't bias the grid, it would be completely redundant and would actually be in in // with the volpot turning it into a 50K pot of some sort.
Standard industrial practice is no DC offset on any source output.
It may be wishful thinking on my part but I still have to encounter a device that had DC on the output, unless faulty.
And while we're at it, ever wondered where the bass went when two caps are put in series?
That's the idea and it works miracles in this digital age.
Close enough...has anyone wondered what exactly it is that set a 5962 apart from a mainstream 6SN7?
You'll all hate me if I did...
Cheers,
Brett-San,
If we to throw more money at it, yes an LCLC is the better filter.
With the valved regulator in place it would be overkill in this instance, YMMV.
Regarding the CCS, the only ones I find sonically unobtrusive are the one by master Gary Pimm.
Anything else qualifies as hybrid to my ears....I have a gut feeling you might agree...
Runeight,
No, it isn't.
That resistor won't bias the grid, it would be completely redundant and would actually be in in // with the volpot turning it into a 50K pot of some sort.
Standard industrial practice is no DC offset on any source output.
It may be wishful thinking on my part but I still have to encounter a device that had DC on the output, unless faulty.
And while we're at it, ever wondered where the bass went when two caps are put in series?
That's the idea and it works miracles in this digital age.
Close enough...has anyone wondered what exactly it is that set a 5962 apart from a mainstream 6SN7?
You'll all hate me if I did...
Cheers,
fdegrove said:
There are tons of low I rating chokes surlus for cheap, so why not?
Overkill? Maybe, but the less work regs do the less obtrusive they are IME.
Variations on the DN2540's like on Bas' site are excellent too.
currently listening thru
12k loaded ECC99 - 6V6GT via LL1620 (is this overkill in this application?) in 11k5 and it's very, very nice. All differential of course.
Yes, you are of course correct Frank, and my answer here was too flip.
So, burnedfingers, there is a choice to be made.
Many audio DIYers don't like capactors and avoid them at all costs. I know that this topic has been endlessly discussed.
On the other hand, the small amount of grid current that will flow through the volume pot can damage the materials as the wiper travels over the resistor.
MHO is to reduce caps from 3 to 1 ala one of the pictures I posted, try an inexpensive volume pot and see what happens. If/when you get noise from the pot, change it out for an attenuator or put a cap in as per Frank's schematic.
I am less convinced of the need for the regulated supply for this amp, but I understand some the reasons given (and I know that Frank and Brett have a better feel for this). My guess is that you might be wanting to keep this project in some kind of budget. If so, I think that a CLCRC PS would be good enough to build first.
Actually, since you want some channel separation, this would do the trick and, perhaps, keep the cost reasonable:
R C (Left)
C L C
R C (Right)
I think that Frank's favorite Schottkys would be best for the rectifiers, but a good old tube rectifier might be more fun.
Frank, I would like to know this answer. I thought that the 5691-5693 were "ruggedized" versions of a 6sl7, 6sn7, 6sj7(?), with longer heater life?, better materials?, and somewhat better construction? whatever?. But I don't know what the specific application targets were back then.
Or maybe its just the red base . . . .
Quote)
Many audio DIYers don't like capactors and avoid them at all costs. I know that this topic has been endlessly discussed.
On the other hand, the small amount of grid current that will flow through the volume pot can damage the materials as the wiper travels over the resistor.
******************************************************
You have brought up some very good points here. I feel I should tread toward the safe side and go with the additional cap or two. I occasionally use my project line amps with SS gear to have friends audition the sonic benefits of the tube gear. All have been impressed. I don't really want to chance the stray event of DC's possible damage to SS gear.
Quote)
I am less convinced of the need for the regulated supply for this amp, but I understand some the reasons given (and I know that Frank and Brett have a better feel for this). My guess is that you might be wanting to keep this project in some kind of budget. If so, I think that a CLCRC PS would be good enough to build first.
******************************************************
At first I didn't see the need for regulated supplies and reguarded them as tweeks. I became a believer after playing with the VR tubes and auditioning a line amp that was the same circuit as mine only featured a regulated supply. The result is unbelieveable and needs to be experienced by all. The cost in a minimal factor in my projects.
I will try this with Frank's regulated supply and Frank's Schookky's and drop the tube regulator idea.
Quote)
has anyone wondered what exactly it is that set a 5962 apart from a mainstream 6SN7?
Don't tell me I paid $80.00 for a pair of 6SN7's with red bases. Ok Frank I give.... tell me.
Joe
Many audio DIYers don't like capactors and avoid them at all costs. I know that this topic has been endlessly discussed.
On the other hand, the small amount of grid current that will flow through the volume pot can damage the materials as the wiper travels over the resistor.
******************************************************
You have brought up some very good points here. I feel I should tread toward the safe side and go with the additional cap or two. I occasionally use my project line amps with SS gear to have friends audition the sonic benefits of the tube gear. All have been impressed. I don't really want to chance the stray event of DC's possible damage to SS gear.
Quote)
I am less convinced of the need for the regulated supply for this amp, but I understand some the reasons given (and I know that Frank and Brett have a better feel for this). My guess is that you might be wanting to keep this project in some kind of budget. If so, I think that a CLCRC PS would be good enough to build first.
******************************************************
At first I didn't see the need for regulated supplies and reguarded them as tweeks. I became a believer after playing with the VR tubes and auditioning a line amp that was the same circuit as mine only featured a regulated supply. The result is unbelieveable and needs to be experienced by all. The cost in a minimal factor in my projects.
I will try this with Frank's regulated supply and Frank's Schookky's and drop the tube regulator idea.
Quote)
has anyone wondered what exactly it is that set a 5962 apart from a mainstream 6SN7?
Don't tell me I paid $80.00 for a pair of 6SN7's with red bases. Ok Frank I give.... tell me.
Joe
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