Can someone of you tube buffs design a very simple one-triode line stage for me (component values only)?
I have a E88CC, I like to have about 10x gain at most (or less) and a supply voltage as low as possible, better with a CC4 like CCS instead of the anode resistor.
Is there a problem runnning this tube with - say - 60V only ?
Yes, I know, I do know very little about tubes...
Thanks,
Klaus
I have a E88CC, I like to have about 10x gain at most (or less) and a supply voltage as low as possible, better with a CC4 like CCS instead of the anode resistor.
Is there a problem runnning this tube with - say - 60V only ?
Yes, I know, I do know very little about tubes...
Thanks,
Klaus
there are 100s of basic line stages for E88CC
but not for you at this time
it seems that way any how
but not for you at this time
it seems that way any how
Klaus,lohk said:
A 6DJ8 has a mu of about 30, so loaded with a CCS as an anode load, will have a gain of about 30.
Why the requirement for such a low B+?
With a B+ of 60V, accounting fo the loss across the CCS and Rk, you will have about 40V or so across the tube itself. To get 1V grid voltage (redbook CD is 2.8Vpeak) you are down at Ia=1.6mA, so you'll need to attenuate the input before it can hit the grid and will have a Zout of about 5k. IME, 6DJ8's sound really awful down low needing several mA at least to come alive.
A better alternative would be a 6H30pi which is a hell of a lot better tube than a 6DJ8, running say Va=100V, Vg = -5V, Ia=20mA (where mu and gain is about 16) with a CCS. Using a 150V B+ this will give you tons of undistorted swing out an output Z of about 1k3 and a very nice sounding linestage.
The CCS loaded 12B4A stage I keep talking about would be viable too, if a gain of 6 is OK.
Lastly, why do you want or need a linestage with a gain of 10?
Cheers
THE GAIN BURNERS
Hi Klaus,
I second that.
IMO even the admittedly very linear 6H30PI would have way too much gain for a CD/line preamp.
The 6C19P is another candidate for this kind of application.
Better run some current through the tubes then to starve them I'd say.
If you still decide to put that E88CC to use you better start around B+250 without CCS or B+160 with CCS and bias it for at least Vg -8.
The higher your B+ the greater the dynamic range and headroom.
Add good PSRR and you have yourself a ticket to sonic audio heaven.
Cheers,😉
Hi Klaus,
I second that.
IMO even the admittedly very linear 6H30PI would have way too much gain for a CD/line preamp.
The 6C19P is another candidate for this kind of application.
Better run some current through the tubes then to starve them I'd say.
If you still decide to put that E88CC to use you better start around B+250 without CCS or B+160 with CCS and bias it for at least Vg -8.
The higher your B+ the greater the dynamic range and headroom.
Add good PSRR and you have yourself a ticket to sonic audio heaven.
Cheers,😉
µ of 10 huh?
pretty damn useless if you ask me, but there are a lot of DHT's used in 20's/30's radios with low gain, generally pretty linear.
(If you want to mess with a low µ tube)
something like #30 has a gain around there, seems pretty linear and still reasonably cheap.
but with a 2v 60ma fil you probably wouldnt even notice its glowing 😛
maybe fork out more cash for an 01A or similar.
well, look through the data for the old double digit tubes, see if you find something neat, and cost effective..
#30
pretty damn useless if you ask me, but there are a lot of DHT's used in 20's/30's radios with low gain, generally pretty linear.
(If you want to mess with a low µ tube)
something like #30 has a gain around there, seems pretty linear and still reasonably cheap.
but with a 2v 60ma fil you probably wouldnt even notice its glowing 😛
maybe fork out more cash for an 01A or similar.
well, look through the data for the old double digit tubes, see if you find something neat, and cost effective..
#30
RADIO GAGA.
Hi Colt45,
As much as I like the #30...I don't want the wrath of the ham guys.😀
Ciao,😉
Hi Colt45,
As much as I like the #30...I don't want the wrath of the ham guys.😀
Ciao,😉
I'm reluctant to recommend DHTs to people without much experience with tubes, as they <i>can</i> be an order of magnitude more difficult to working well esp at line level and it's the detail application of DHTs that lift them out of the ordinary. A #30, with a 2V fil (and a weedy 60mA If) would probably be easier than some, like a 572-30 as Eric Barbour tried successfully.Colt45 said:
Brett said:
fair enough, I didn't notice he was new to tubes.
we should probably save the #30's for the radio guys anyways 😉
Just a small subjective comment here. I've never really understood the purpose of active line stages which simply provide a bit of gain and lower/constant output resistance. These devices usually inflict an additional veil on the sound which IME doesn't quite justify their purpose. A typical example for such a line stage is a resistor loaded ECC88, even at normal anode voltages . No idea how CJ Art sounds but probably not that great. The only line stages which i find justifiable are the ones which really do something for the sound. When successful they can inject some life and dynamics and make the entire experience so much more exciting. I have learnt to associate such sound with juicy, high current valves and either transformer or choke loading. SS CCS invariably imrint a SS signature.
Very probably the best line stage is passive, transformer based but i've never had the fortune to hear one.
In short instead of dealing with a mediocre line stage i'd rather have a passive attenuator and try to get the impedances right.
cheers
peter
Very probably the best line stage is passive, transformer based but i've never had the fortune to hear one.
In short instead of dealing with a mediocre line stage i'd rather have a passive attenuator and try to get the impedances right.
cheers
peter
Well said. Just one amendment...
Instead of dealing with a mediocre line stage i'd rather have a passive attenuator and get the impedances right.
😉
To my experiance an E88CC (6dj8) needs a plate voltage of 90 or 100V and near to 5 mA to work reliable and in its more linear portion.
I have built more than 12 peamps, vacuum, solid state and hybrids, from very complex to very simple and ended with my current, excellent sounding 6dj8 in a simple plate follower which is a reference to me sonicwise.
This preamp drives my Zen and Aleph amps with no problem, 10K input impedance.
This is the description of the active portion of the preamp.
160v to the top of the rp and 102v to the plate with 16K rp and 408 Ohms rk. Whith this values it sinks 5.7 mA.
The grid stopper is 1.7K and feedback is 18K. Total output cap is 10 uf.
The power supply is solid state regulated and and well filtered with a CRCLCRC after the regulator, at the beginning of this filtration there are arround 300v.
At rhe beggining was using 150V at the plate but found that this is not reliable even if the specs for the tube (as I remember) will give this value as maximum allowable, it also says that it can pull 15mA but this is a no,no for me.
Can someone tell me which is the best way of measuring the output impedance for a preamp?
I have built more than 12 peamps, vacuum, solid state and hybrids, from very complex to very simple and ended with my current, excellent sounding 6dj8 in a simple plate follower which is a reference to me sonicwise.
This preamp drives my Zen and Aleph amps with no problem, 10K input impedance.
This is the description of the active portion of the preamp.
160v to the top of the rp and 102v to the plate with 16K rp and 408 Ohms rk. Whith this values it sinks 5.7 mA.
The grid stopper is 1.7K and feedback is 18K. Total output cap is 10 uf.
The power supply is solid state regulated and and well filtered with a CRCLCRC after the regulator, at the beginning of this filtration there are arround 300v.
At rhe beggining was using 150V at the plate but found that this is not reliable even if the specs for the tube (as I remember) will give this value as maximum allowable, it also says that it can pull 15mA but this is a no,no for me.
Can someone tell me which is the best way of measuring the output impedance for a preamp?
I agree with you about linestages, but unfortunately people seem to think they need them. The CJ ART has 26dB of gain(!) from 10 -88 stages in parallel. With a CDP as input, and most amps at 1V or so sensitivity, what is anyone going to do with that extra 30dB of gain?analog_sa said:
Again I sort of agree, except for the comment about SS CCS. IME they just remove the "tubey" tubbiness from most circuits. Chokes are nice too, and a more than satisfactory second choice.
My pre is being rebuilt at the moment so that each source passes through the selector, then the TVC (transformer volume control) and out to the poweramps. The phono inputs have their own RIAA preamps of course, but otherwise each source should be able to drive the amps to near clipping on peaks, which equates to about 115dB with no additional linestage.
Cheers
I have a number of datasheets for 6DJ8 / ECC88 / 6922 and the design centre maximums vary between 250 - 300 Va and 20mA Ia.apassgear said:
All,
thank you for your answers. I had to travel abroad and could not respond earlier.
Just to make it clear: I do want to make a small tube line stage, no matter if it is a good idea or not to some of you. I want to check it out myself, and a line stage seems the easiest way to go. I want that tube sound ! ( - and if it does not work - like so many other amps I heard - I can always use it in my studio to flavour my recordings with some sweet harmonics...)
Thank you, Tony: That sounds very promising. I will try that.
Grid stopper means in series to the grid ?
And feed back runs from the plate to the input (before the gridstopper), I suppose. What is the resulting gain of that stage, with feedback ? How is the sound difference between with feedback and without?
Klaus
thank you for your answers. I had to travel abroad and could not respond earlier.
Just to make it clear: I do want to make a small tube line stage, no matter if it is a good idea or not to some of you. I want to check it out myself, and a line stage seems the easiest way to go. I want that tube sound ! ( - and if it does not work - like so many other amps I heard - I can always use it in my studio to flavour my recordings with some sweet harmonics...)
Thank you, Tony: That sounds very promising. I will try that.
Grid stopper means in series to the grid ?
And feed back runs from the plate to the input (before the gridstopper), I suppose. What is the resulting gain of that stage, with feedback ? How is the sound difference between with feedback and without?
Klaus
THE JOCKO STOPPERS
Hi,
Yes.
It has to be soldered as close as possible to the grid otherwise there is no point in having it there.
No.
From output to the cathode of the first stage is more common.
Why do you need to apply feedback anyway?
Aren't you talking about a single stage preamp?
Cheers, 😉
Hi,
Yes.
It has to be soldered as close as possible to the grid otherwise there is no point in having it there.
No.
From output to the cathode of the first stage is more common.
Why do you need to apply feedback anyway?
Aren't you talking about a single stage preamp?
Cheers, 😉
Hi
The line stage described by Tony is very similar to the Music Reference RM5 line stage.
The line stage of the RM5 is a grounded cathode stage containing one half of a 6DJ8.
B+ =170 V, Rk=475 ohms, Ra=22k.
Input passes through a 100k balance pot, then a 100k volume pot followed by a variable input resistance network (can be set at 10k, 82.5k or 92.5k) connected to the grid.
Feedback is taken from output after the output capacitor (5uF) back to the grid. The feedback is variable in the RM5. The feedback resistor can be set at 150k or 450k and is connected directly to the grid.
Feedback depends on a)the chosen value of the resistance network at the grid, b) the chosen value of the feedback resistor, c) the setting of the volume - when volume is increased, the feedback is increased as well because the feedback signal looks back into a higher resistance.
Tony did not mention the value of his volume pot but only his feedback resistor.
I do not want to publish the schematic here as the RM5 is still in production.
Torben
The line stage described by Tony is very similar to the Music Reference RM5 line stage.
The line stage of the RM5 is a grounded cathode stage containing one half of a 6DJ8.
B+ =170 V, Rk=475 ohms, Ra=22k.
Input passes through a 100k balance pot, then a 100k volume pot followed by a variable input resistance network (can be set at 10k, 82.5k or 92.5k) connected to the grid.
Feedback is taken from output after the output capacitor (5uF) back to the grid. The feedback is variable in the RM5. The feedback resistor can be set at 150k or 450k and is connected directly to the grid.
Feedback depends on a)the chosen value of the resistance network at the grid, b) the chosen value of the feedback resistor, c) the setting of the volume - when volume is increased, the feedback is increased as well because the feedback signal looks back into a higher resistance.
Tony did not mention the value of his volume pot but only his feedback resistor.
I do not want to publish the schematic here as the RM5 is still in production.
Torben
lohk said:
Most of your questions have been answered during my absence but here are other comments:
This line stage is a very basic stage you can find it in any text book as the most common gain configuration. I did not copy this setup from any product and have been using it for a couple of years with no problems it's very stable, rock solid, silent and reliable.
Initialy I was using it without feedback and sounded very good but some time ago I decided to try its respose with the input and output interconnects (with 10K resistive load, 1 resistors attached across the loose end of the output cable) atached to the preamp an found that the respose wasn't that nice so started to test feeback resistors until I got what I liked. Its true what others may say, the FB resistor is very low to tube standards but this gave me a much better low freq square wave respose and a higher freq. rolloff at the top.
Using the FB resistor greatly tightens low freq for a very fast respose of your bass speaker and gives a nice square wave at the top. Since this stage has a gain which exceeds what's required for a preamp to a great degree the addition of FB is wellcomed. Try different values of FB resistors untill you are satisfied with the results but i woulden't use more than 50K since the effect is slim. Since a lower FB resistor will mean you will have a lower gain you will have to set it also taking this in consideration.
The operating point for the tube is rather low but this gives a slightly heavier low frequency which in most cases is a welcomed deviation.
Be aware that you may find that there are some wrongly branded tubes on the market, they may say 6DJ8, 6922, ECC88 or whatever but they may not be that, unfortunately you can not say by looking at them so buy from a reliable source or test them to make sure they are linear devices.
I have two brands, these are AEG ECC88 or AMPEREX 6922 (made in Holland) gold colored leads but use the latter one.
In the circuit I use a 80K stepped attenuator, 100K would be also a good selection and more standard but anything above 50K is OK.
I did not mention on my previous post about two other resistors, maybe because they were to obvious, you will need to add a referece to ground for the grid, the usual value for these resistor is 0.5M (500K) or somewhat less. Connecting the grid to ground before or after the grid stopper but close to the terminal of the tube, I use the second alternative which seems to be less common.
The other resistor goes after the output cap to ground you can use a value of 100K to 500K. And yes, the FB resistor also comes from this point to the grid, but try to put the resistor itself as colse to the grid terminal as possible.
Tube stages are very flexible so feel free to experiment with different reistor values only taking care not to exceed the tube dissipation, in other words check you don't go over the current stated for the tube, in this case around 15 mA (which is high for me, I would never exceed 8 mA for 6DJ8 for a reliable work).
Klaus, do you have a scope?
Klaus,
If you like to connect the FB to the cathode you need to add a series capacitor. I prefer the grid connection which dosen't need a capacitor since both points are at ground level.
If you like to connect the FB to the cathode you need to add a series capacitor. I prefer the grid connection which dosen't need a capacitor since both points are at ground level.
DARK SIDE OF THE MOON.
Hi,
Uh?
Seems you guys are talking in the dark here....
A pic please?
What have I missed?
Ciao,😉
Hi,
Uh?
Seems you guys are talking in the dark here....
A pic please?
What have I missed?
Ciao,😉
Re: THE JOCKO STOPPERS
Yes, it's a single stage preamp, 1/2 of the tube for each channel, so only a one tube preamp.
Feedback is added to tighten the responce and lower the gain if you wish. I know this will turn a tube to sound less tubelike and for most DHT hardcores this is not suitable. But in the other hand it's an easy preamp for begginers like Klaus who can experiment with this simple stage and sound better than a SS to me, so far at least.
I would like to try a DHT without going overboard with cost and not to complicated. Several have been mentioned on this thread.
Is the #30 a good starting point? Any brand recommended?
Can an air coil loading for the plate be used?
Do someone have a circuit proposal?
fdegrove said:
Yes, it's a single stage preamp, 1/2 of the tube for each channel, so only a one tube preamp.
Feedback is added to tighten the responce and lower the gain if you wish. I know this will turn a tube to sound less tubelike and for most DHT hardcores this is not suitable. But in the other hand it's an easy preamp for begginers like Klaus who can experiment with this simple stage and sound better than a SS to me, so far at least.
I would like to try a DHT without going overboard with cost and not to complicated. Several have been mentioned on this thread.
Is the #30 a good starting point? Any brand recommended?
Can an air coil loading for the plate be used?
Do someone have a circuit proposal?
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