well, finally i have found a little bit time to play with lm317 ccs in cathode and with tl431 ccs in cathode...sch attached.... the one with tl431 sounded less harsh .... i could listen to it a little bit easier than the one with lm317.... the bass was a little bit stronger with tl431 ccs..... all in all not a spectacular difference but a would go on a tl431........ bypass caps are BG 220uF/50V and Mundorf MCap 1uF/400V
question... how to make ccs in the sch attached better........
would bypassing adj to ground with a cap help a little bit? how big cap there if it would?
question... how to make ccs in the sch attached better........
would bypassing adj to ground with a cap help a little bit? how big cap there if it would?
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By all means, do experiment with CCSs in the cathode circuit. That's part of the fun of audio design.
But, it strikes me that efforts to tweak the CCS in a BYPASSED cathode circuit is like trying to make a race car go faster by experimenting with various paint schemes. Sure, some paint types may have a slightly lower coefficient of wind drag, but wouldn’t you rather put your efforts into better tires or a better fuel injection system, especially if you have many options with these?
In the cathode CCS the bypass capacitor SHOULD completely dominate the sound. If you can hear any real differences among CCSs, it means the cap or cap combination is not yet doing its job – that is to “short” out all audio to ground across the full audio band. I would suggest experimenting with various combinations of large cap types with various combinations of smaller bypass caps until the CCSs sound alike; then the cap bypass is doing its job. Fortunately in the cathode circuit you don’t need high voltage caps, so you have more options. A number of paralleled polypropylene caps, bypassed further with small polystyrene, PIO and/or Teflon might be worthwhile.
Try also to add a small resistor in series with the CCS to dampen any unexpected RLC activity...
But, it strikes me that efforts to tweak the CCS in a BYPASSED cathode circuit is like trying to make a race car go faster by experimenting with various paint schemes. Sure, some paint types may have a slightly lower coefficient of wind drag, but wouldn’t you rather put your efforts into better tires or a better fuel injection system, especially if you have many options with these?
In the cathode CCS the bypass capacitor SHOULD completely dominate the sound. If you can hear any real differences among CCSs, it means the cap or cap combination is not yet doing its job – that is to “short” out all audio to ground across the full audio band. I would suggest experimenting with various combinations of large cap types with various combinations of smaller bypass caps until the CCSs sound alike; then the cap bypass is doing its job. Fortunately in the cathode circuit you don’t need high voltage caps, so you have more options. A number of paralleled polypropylene caps, bypassed further with small polystyrene, PIO and/or Teflon might be worthwhile.
Try also to add a small resistor in series with the CCS to dampen any unexpected RLC activity...
dear Brian,
i agree with You.... but i can hear the difference between them (and i have Black Gate 220uF and Mundorf MCap 1uF i parallel).... this two capacitors should be enough but......
i can hear that LM317 is behaving very strangely at treble frequencies......
TL431 is better there.....
i agree with You.... but i can hear the difference between them (and i have Black Gate 220uF and Mundorf MCap 1uF i parallel).... this two capacitors should be enough but......
i can hear that LM317 is behaving very strangely at treble frequencies......
TL431 is better there.....
Sunrise,
I don't doubt your experience here. Try adding a series resistor to the CCS.
I don't think so. Try adding smaller PP or PIO caps in parallel. Cathode bypassing is not easy since the impedances are are so low. You really need to knock down the treble impedance of the cap combination. Make sure cap wiring is short to the cathode and to ground to reduce series inductance.
I don't doubt your experience here. Try adding a series resistor to the CCS.
I don't think so. Try adding smaller PP or PIO caps in parallel. Cathode bypassing is not easy since the impedances are are so low. You really need to knock down the treble impedance of the cap combination. Make sure cap wiring is short to the cathode and to ground to reduce series inductance.
Sparkle , why you don´t use a Fet controlled by TL431 ?
You scheme with one triode that have resistor on anode is limited design by itself.
Why you did not use SRPP , it is far better circuit thah can be tweaked with current source like yours.
Remove that electrolytic cap that is on chatode to ground circuit.
You scheme with one triode that have resistor on anode is limited design by itself.
Why you did not use SRPP , it is far better circuit thah can be tweaked with current source like yours.
Remove that electrolytic cap that is on chatode to ground circuit.
Gasho - well, i have been doing tube preamplifiers for a long time... every one of them had problems related sound.... some of them were my designs and some of them were other designs.... i don't say that i have tried everything but only a lot.... did not try srpp ....but in my quest i have concluded that common cathode sounds the best in my opinion... so i have played with it trying chokes in plate, resistors in cathode, plate in cathodes...... and i have stumbled on ccs in cathode and also tried it... it seemd to me that this is a step forward that will leave the qualities that i have heard in basic circuit..... so here i am now.... 🙂
who knows where i will land at last.... maybe on some srpp... is srpp your preffered type of the circuit or you just recomend it for the 12b4?
who knows where i will land at last.... maybe on some srpp... is srpp your preffered type of the circuit or you just recomend it for the 12b4?
Brian,
i agree with you. That is why i have heard some sonic disadvantages of the Lm317 ccs. I will try to remove it for sure. But for now i would like to make the best ccs possible so that i will only make it better with the capacitors in parallel.
Here it is my quest on how to make better ccs for putting in the cathode. After that i will put capacitors in parallel so that they remove anything that might be left in treble 🙂
The quest for ccs is here what is important to me- to find the better one than LM317 - why to use LM317 when it is allready used. Why not TL431 or something better -exploration. 🙂
You know ......😀
i agree with you. That is why i have heard some sonic disadvantages of the Lm317 ccs. I will try to remove it for sure. But for now i would like to make the best ccs possible so that i will only make it better with the capacitors in parallel.
Here it is my quest on how to make better ccs for putting in the cathode. After that i will put capacitors in parallel so that they remove anything that might be left in treble 🙂
The quest for ccs is here what is important to me- to find the better one than LM317 - why to use LM317 when it is allready used. Why not TL431 or something better -exploration. 🙂
You know ......😀
I haven't tried using a CCS bypassed with a cap, but I did try an LM317 under a longtail pair and it oscillated quite a bit. (Don't remember exactly what frequency, but I think it was in the high 100's of kHz or low MHz.) I replaced it with a cascode mosfet as in Horowitz and Hill and that worked better. Sounded better too. 😉
thnx David,
i have noticed that LM317 is oscilating .... bypassing with BG and 1uF MCap didn't solved the problem entirelly..... so i build TL431 and it is o.k. now.....
thnx for Your information
sunny
i have noticed that LM317 is oscilating .... bypassing with BG and 1uF MCap didn't solved the problem entirelly..... so i build TL431 and it is o.k. now.....
thnx for Your information
sunny
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