jean-paul, with cars( well, pick-up trucks anyway), a 5th Wheel is a type of super trailer hitch, useful for carrying all sorts of heavy things. Now I know what you meant, but having a truck with a 5th wheel hitch...LOL
cheers,
Douglas
OK let's make it a second steering wheel then 🙂 It is just that adding something superfluous is common in this section but this is not standard design practice elsewhere and it creates more issues than it solves. Most of my designs would not function when I would just do something nor would they be usable with other devices.
Since I see quite some installations and the gain mismatch issue is simply common amongst these tube guys I think it is safe to say that practically no one needs gain in a preamp form when using modern sources. All added stuff is just added stuff that will not improve already processed good signals that already passed a few stages.
Let's simplify it to the bare essence: are you satisfied when using your 2Veff output low Zout DAC to your high gain, high Zin (tube) amplifier and is volume OK at 9 o clock? Then you don't need anything extra between them. You could invest your time in improving the source or the power amplifier if necessary. In practice one sees that without a preamp sensitivity of the tube amplifier is often too high so this is also in contradiction with adding even more gain. If someone can explain why position 1 of the volume control needs to lead to high volume and/or distortion please enlighten me.
Since I see quite some installations and the gain mismatch issue is simply common amongst these tube guys I think it is safe to say that practically no one needs gain in a preamp form when using modern sources. All added stuff is just added stuff that will not improve already processed good signals that already passed a few stages.
Let's simplify it to the bare essence: are you satisfied when using your 2Veff output low Zout DAC to your high gain, high Zin (tube) amplifier and is volume OK at 9 o clock? Then you don't need anything extra between them. You could invest your time in improving the source or the power amplifier if necessary. In practice one sees that without a preamp sensitivity of the tube amplifier is often too high so this is also in contradiction with adding even more gain. If someone can explain why position 1 of the volume control needs to lead to high volume and/or distortion please enlighten me.
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Hi Bas,
Lets try to help you. Many years ago I built a line-stage with 6C19P. I did't like it. The sound was hard and not musical enough for my taste. Each tube has it's own flavor of sound and no matter what you can't completely change it. As suggested please try the volume pot before and try a good quality film cap as cathode bypass. Also you may try
to change the op point and see if that helps. For my tastes Silmic II is good as cathode cap.
If I'm not wrong gain of 6C19P is less that 3, since you are using resistor as plate load gain for this case will not be more that 2.5x. If it is OK with you fine no problem.
I had built number of line-stages over last 20/25 years until I settle with para-feed DHT SE stage. I am happy now. If you are interested we can help you to build one.
Regards
Lets try to help you. Many years ago I built a line-stage with 6C19P. I did't like it. The sound was hard and not musical enough for my taste. Each tube has it's own flavor of sound and no matter what you can't completely change it. As suggested please try the volume pot before and try a good quality film cap as cathode bypass. Also you may try
to change the op point and see if that helps. For my tastes Silmic II is good as cathode cap.
If I'm not wrong gain of 6C19P is less that 3, since you are using resistor as plate load gain for this case will not be more that 2.5x. If it is OK with you fine no problem.
I had built number of line-stages over last 20/25 years until I settle with para-feed DHT SE stage. I am happy now. If you are interested we can help you to build one.
Regards
JP, not all tube amps are high Z-in. Turns out they sound better with small initial stage grid resistances. IFF the linestage can drive the load. That turns out to be no issue as the mu-follower CCS plate load is capable of delivering low, two digit output Z. For such a linestage, it is entertaining to bring an amp to a linestage shoot-out with a 2.2k input Z and watch what happens. Later the reason gets revealed. Educational purposes only.
Not all amps can get away with 2V SE input either... 🙂
And, though now edited, the 6 wheel is a Dually, which is the most likely to be equipped with a 5th wheel, as well as a fifth tire...LOL
cheers,
Douglas
Not all amps can get away with 2V SE input either... 🙂
And, though now edited, the 6 wheel is a Dually, which is the most likely to be equipped with a 5th wheel, as well as a fifth tire...LOL
cheers,
Douglas
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If they can not get away with 2Veff will they get away when amplifying that to even higher levels? Please remember that I mean most of devices not the odd one that needs to be special. Many a tube aficionado makes an ugly face when he sees a 25 kOhm volume potentiometer...so please show your wisdom that low ohmic lines are beneficial. You will be met with more misunderstanding than me in this thread.
Since standardization is common elsewhere extremes are understood to be "one off" and they can't be used with stuff designed to the standards. If one designs for extremes or just designs randomly than there will be chaos. Good sources will be condemned as they misperform in that situation while bad sources may be liked. Apples will be compared to pears....
And there will be loads of gain, impedance mismatches, wrong value coupling caps ... This forum is so big that you guys can define a definitive tube amplifier sensitivity standard that is beneficial for all. It would make interchangeability of devices issue free. Suggestion: 25 kOhm, 1 Veff for full output, DC input so coupling cap always in the output of sources. This to avoid the dreaded 2 caps in series high pass filter.
Since standardization is common elsewhere extremes are understood to be "one off" and they can't be used with stuff designed to the standards. If one designs for extremes or just designs randomly than there will be chaos. Good sources will be condemned as they misperform in that situation while bad sources may be liked. Apples will be compared to pears....
And there will be loads of gain, impedance mismatches, wrong value coupling caps ... This forum is so big that you guys can define a definitive tube amplifier sensitivity standard that is beneficial for all. It would make interchangeability of devices issue free. Suggestion: 25 kOhm, 1 Veff for full output, DC input so coupling cap always in the output of sources. This to avoid the dreaded 2 caps in series high pass filter.
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That part is OK.
Been there done that. Was a three box solution...but it started making terrible noise...I still have to fix that one....801A tube btw. But it is so cumbersome carrying that upstairs to my hobby room to fix it. But I am thinking about reviving it..perhaps with the 4p1l
I did hear a hint of that....after a while. But then again last night after snipping out the cathode bypass caps...it improved.,...I think 😀
Bas, thank you for your interest, but it is not about my line-stage. We have widely available technology and knowhow nowadays to build a hum/noise free DHT line-stage. We can help you to build one according to your need and tastes.
I have built and regularly use parallel 3A5 para-feed single ended line-stage. For 3A5 parameters please check 3A5 DHT – Bartola(R) Valves.
Lets start with gain, since your 6C19P line-stage with 2.5x gain is OK with you so we may consider 2.5x-4x will be great. Now output Z, in my dictionary anything from 600R to 1000R is fine for tube amp domain. May we proceed or we stop here?
Regards
Regards
I have built and regularly use parallel 3A5 para-feed single ended line-stage. For 3A5 parameters please check 3A5 DHT – Bartola(R) Valves.
Lets start with gain, since your 6C19P line-stage with 2.5x gain is OK with you so we may consider 2.5x-4x will be great. Now output Z, in my dictionary anything from 600R to 1000R is fine for tube amp domain. May we proceed or we stop here?
Regards
Regards
You may proceed 🙂 However only tubes in my current stash will be considered such as 4p1l 😀 I have too many tubes to consider buying a type I don't have yet.
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It is good Bas, we move forward with 4p1L then.
We plan to make it resistor loaded circuit first. Our first target is to build a hum/noise free DHT stage, you may make the circuit little complex later on, if needed. Here is the triode curve https://i1.wp.com/www.bartola.co.uk/valves/wp-content/uploads/2018/03/4P1L-PSE-Zaa3K-A2-Po6W.png. We will run it at about 150 volt plate voltage and 12 volt cathode voltage. Now tell us about your plan, do you want to proceed like new PS new signal curcuit etc or you want to reuse any existing set-up?
Regards
We plan to make it resistor loaded circuit first. Our first target is to build a hum/noise free DHT stage, you may make the circuit little complex later on, if needed. Here is the triode curve https://i1.wp.com/www.bartola.co.uk/valves/wp-content/uploads/2018/03/4P1L-PSE-Zaa3K-A2-Po6W.png. We will run it at about 150 volt plate voltage and 12 volt cathode voltage. Now tell us about your plan, do you want to proceed like new PS new signal curcuit etc or you want to reuse any existing set-up?
Regards
Hi minhaj,
I actually have it configured like that as a driver for a long term project I'm doing. I use filament bias and also around 150 volt plate voltage. Rod Coleman filament boards...
I'll definitely use the 21st century maida board...as psu.
I actually have it configured like that as a driver for a long term project I'm doing. I use filament bias and also around 150 volt plate voltage. Rod Coleman filament boards...
I'll definitely use the 21st century maida board...as psu.
Very good, Bas. You easily can convert it as line stage on temporary basis. Actively regulated power supply for line-stage is not my cup of tea. But if you like it it's 100% fine.
When you complete rest of the work please tell us how it sounds. Meanwhile please keep us posted should you need our help to solve any problem. Please remember if you need a active line-stage it's very important that the line-stage is sonically good for your taste and electrically correct for your other equipment, before and after. Request you to note that when you build a good DHT line-stage it will be difficult to replace it but for that you have put some serious effort and time.
Good luck/Regards
When you complete rest of the work please tell us how it sounds. Meanwhile please keep us posted should you need our help to solve any problem. Please remember if you need a active line-stage it's very important that the line-stage is sonically good for your taste and electrically correct for your other equipment, before and after. Request you to note that when you build a good DHT line-stage it will be difficult to replace it but for that you have put some serious effort and time.
Good luck/Regards
Converted to a passive stage. Just a noble pot with a switch for channel selection. Beats the active stage for my ears.
That is my experience also. Aikido (with ECC82 as input/output tube) line stage was okay but too much gain. 3a5 line stage with RC coupling, CCS filament and 15K:600 ohms para-feed transformer is the overall winner for me.
Got me some 3a5's. I've already decided to parallel the two halves and filament bias. Around 10mA per tube. I'll probably use a 4.5:1 output transformer I have (Lundahl LL1660S/25mA)
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Oh! that's great. You may like to follow OP as suggested by Bartola here Filament Bias: a practical example with 3A5 DHT – Bartola(R) Valves. I run 100V 8ma both triodes in parallel in RC loaded parafeed output. If you try it I am sure you will like it. Please keep us posted.
Regards
Regards