that's tricky rule thumbing 
hundred-fold is better
thousand-fold even better
but, with that rule you can't cover all cases, and there are cases of successful breaking the rule
in short:
- you'll hear, with smile, when and if source used is able to drive that pot with ease
-you'll hear, with smile, when and if gain distribution in your signal/amplification chain is not wasting signal with superfluous attenuation
-you'll hear, with smile, when and if signal energy preservation in your system is on highest possible level
hundred-fold is better
thousand-fold even better
but, with that rule you can't cover all cases, and there are cases of successful breaking the rule
in short:
- you'll hear, with smile, when and if source used is able to drive that pot with ease
-you'll hear, with smile, when and if gain distribution in your signal/amplification chain is not wasting signal with superfluous attenuation
-you'll hear, with smile, when and if signal energy preservation in your system is on highest possible level
Maybe these autoformer arrangements like Iron Pumpkin are helping with the "energy preservation" thing (???)
I think this is the point of using autoformers. Must try asap.
superfluous attenuation means "do not exaggerate the gain on the line stage" so that the pot can stay at 4pm instead of 8am?
(do we speak of a pot being open when it's fully turned up, or is it like a circuit, open=off closed=on?)
superfluous attenuation means "do not exaggerate the gain on the line stage" so that the pot can stay at 4pm instead of 8am?
(do we speak of a pot being open when it's fully turned up, or is it like a circuit, open=off closed=on?)
well, enough Iron Pump(kin)ing here, everything explained in related threads
speaking strictly and heavily subjective, I prefer inductive attenuator to resistive
and we really need to make distinction, when talking about preamps, between active stage of choice, and attenuator we are planning to use with it
active stage is and must be matter of inspired choice, while we also must be aware of importance of attenuator used - better it is, final result is better, allowing active stage to fully shine
when speaking of resistive attenuators, differences between decent ones are small, and only you can say is asked price worthy of paying for ...... plenty of decent solutions around
speaking strictly and heavily subjective, I prefer inductive attenuator to resistive
and we really need to make distinction, when talking about preamps, between active stage of choice, and attenuator we are planning to use with it
active stage is and must be matter of inspired choice, while we also must be aware of importance of attenuator used - better it is, final result is better, allowing active stage to fully shine
when speaking of resistive attenuators, differences between decent ones are small, and only you can say is asked price worthy of paying for ...... plenty of decent solutions around
Waynes Line Stage is one of the best preamps you can build at the moment
from the diyAudio - offerings. My opinion.
It is very detailed and 'accurate' sounding but not too 'clean' or harsh.
I also like it as a headphoneamp.
But I will put my ACP+-pre, B1 KORG NUTUBE-pre in a similar range like
the WLS. But with a bit more warmer charcter. Although the B1 KORG is very 'adjustable'.
But I also like my
BA-3 - pre (gain machine)
B1 (o.k. - buffer preamp)
Aleph P1.7 -pre
Zetex ZVN3310/ZVP3310- pre (recipe from Nelson Pass article: 1998 - DIY OP Amps)
Balanced Zen Linestage
SOZ
BOZ
If anybody asks me: Which preamp should I built?
I would answer: All! Because you only can know if they have been playing in your system / setup, you have listened to them with your music and your
'taste'. And you will have different impressions to my ones.
Now let us build preamps, poweramps, active crossovers,....
mix and match - enjoy the music!
Cheers
Dirk
from the diyAudio - offerings. My opinion.
It is very detailed and 'accurate' sounding but not too 'clean' or harsh.
I also like it as a headphoneamp.
But I will put my ACP+-pre, B1 KORG NUTUBE-pre in a similar range like
the WLS. But with a bit more warmer charcter. Although the B1 KORG is very 'adjustable'.
But I also like my
BA-3 - pre (gain machine)
B1 (o.k. - buffer preamp)
Aleph P1.7 -pre
Zetex ZVN3310/ZVP3310- pre (recipe from Nelson Pass article: 1998 - DIY OP Amps)
Balanced Zen Linestage
SOZ
BOZ
If anybody asks me: Which preamp should I built?
I would answer: All! Because you only can know if they have been playing in your system / setup, you have listened to them with your music and your
'taste'. And you will have different impressions to my ones.
Now let us build preamps, poweramps, active crossovers,....
mix and match - enjoy the music!
Cheers
Dirk
I'm getting the parts together for a BA2018 linestage and have a couple of questions regarding the power supply.
I'm looking at the PS-22 and Dual-LV-Reg both from Glassware/Tube CAD for this build. The PS-22 requires a CT transformer, while the Dual-LV-Reg requires a dual secondary transformer.
If I buy a dual secondary transformer, can I wire the secondaries in series to create the CT?
This circuit requires a 18v, so the regulator would be specified that way, should the transformer also be 18V? I'm thinking of either the AN-0218 (25 VA dual 18V secondary) or AN-0518 (50VA dual 18 V secondary) from Antek. Am I on the right track?
I'm looking at the PS-22 and Dual-LV-Reg both from Glassware/Tube CAD for this build. The PS-22 requires a CT transformer, while the Dual-LV-Reg requires a dual secondary transformer.
If I buy a dual secondary transformer, can I wire the secondaries in series to create the CT?
This circuit requires a 18v, so the regulator would be specified that way, should the transformer also be 18V? I'm thinking of either the AN-0218 (25 VA dual 18V secondary) or AN-0518 (50VA dual 18 V secondary) from Antek. Am I on the right track?
to A Gordn Pym #2369
Good morning A Gorden Pym,
you are on the right track.
You need dual secondaries in your transformer to create the symmetrical voltage.
Center tap will be referenced to ground ( but after the rectifier/ filtercaps/regulator).
Many regulators can handle up to 37V in (but check datasheet!).
Greets
Dirk
Good morning A Gorden Pym,
you are on the right track.
You need dual secondaries in your transformer to create the symmetrical voltage.
Center tap will be referenced to ground ( but after the rectifier/ filtercaps/regulator).
Many regulators can handle up to 37V in (but check datasheet!).
Greets
Dirk
A bunch! Check out Zenmod's Iron Turtle for the ultimate in attenuation!
Soon as I dump my ethereum I havi'n one! That said, I'm using the big blue Alps on a few builds, including my 2018 line stage, as well as Iron pre. Has a nice feel as well. And have few complaints ☺️
Russellc
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Can someone explain the theory of operation of this circuit? Not just hand-waving, but real engineering detail? I would like to understand the rationale for the dual current sources, the cascode transistors Q12 and Q13, and Q11.
Looking at the video lecture, someone from the audience seemed to have the same questions, but they didn't get answered.
Thanks.
-Henry
Looking at the video lecture, someone from the audience seemed to have the same questions, but they didn't get answered.
Thanks.
-Henry
The dual current sources simulate P channel devices or act as floating current sources. The bottom cascode transistors are just that cascodes. They are a reflection of the top ones and also help with dissipation on the fets. The other PNP device you mention is a straight forward emitter follower. The circuit was done to be able to use available parts, since P channel low noise are hard to get.
Thanks for the reply, Wayne.
Because Q3 and Q4 are reasonably good constant current sources, there's close to zero signal current flowing in R14 and therefore Q11 and Q9 have nothing to amplify.
I thought at first maybe you were exploiting the nonlinearity of Q3 and Q4 to implement some kind of sneaky distortion cancellation scheme. But I guess not, else you would have mentioned it.
It seems like the intent was to make a phase inverter, with balanced drive signals coming from Q5 and Q12. But that's not how this circuit works.
I agree with the gentleman from the lecture who asked why you don't just replace Q3 and Q4 with a single current source, get rid of R3, and make R1 and R2 330 Ohms.
The gain of the input stage is an order of magnitude lower than you show in your slide.
It's hard to hear the audience comments at the end of the video, but from your response it seems like someone said you could remove a lot of components and still get the same performance. If so, I agree with that too.
-Henry
Because Q3 and Q4 are reasonably good constant current sources, there's close to zero signal current flowing in R14 and therefore Q11 and Q9 have nothing to amplify.
I thought at first maybe you were exploiting the nonlinearity of Q3 and Q4 to implement some kind of sneaky distortion cancellation scheme. But I guess not, else you would have mentioned it.
It seems like the intent was to make a phase inverter, with balanced drive signals coming from Q5 and Q12. But that's not how this circuit works.
I agree with the gentleman from the lecture who asked why you don't just replace Q3 and Q4 with a single current source, get rid of R3, and make R1 and R2 330 Ohms.
The gain of the input stage is an order of magnitude lower than you show in your slide.
It's hard to hear the audience comments at the end of the video, but from your response it seems like someone said you could remove a lot of components and still get the same performance. If so, I agree with that too.
-Henry
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DC Offset
Hi all, I have a question around the DC offset of this line stage. I built this a little while ago and absolutely love it! About the same time I put this in my system I started having troubles with my Behringer Inuke DSP amp that drives my bass section, this now randomly goes into protection mode.
I’ve just read that this could be caused by DC offset in the pre amp section. I spent a bit of time trying to get the DC offset to zero but as you know it drifts around a bit. Is there a way we can lock this drift in better?
If may not be the issue with my amp but a place to start.
Appreciate your thoughts on how to deal with this.
Thanks
Hi all, I have a question around the DC offset of this line stage. I built this a little while ago and absolutely love it! About the same time I put this in my system I started having troubles with my Behringer Inuke DSP amp that drives my bass section, this now randomly goes into protection mode.
I’ve just read that this could be caused by DC offset in the pre amp section. I spent a bit of time trying to get the DC offset to zero but as you know it drifts around a bit. Is there a way we can lock this drift in better?
If may not be the issue with my amp but a place to start.
Appreciate your thoughts on how to deal with this.
Thanks