Hearing Aid...
Hi,
Hearing aid batteries on the low side again?
Shows how resolving your system is or should one say your "mind"?
Do whatever you like within your limitations, Joel, I can't care less, just don't hamper people with a bit more ambition than yourself, will you?
Show us you can let the RDH go and fly on your own wings, its high time for you to do so IMHO.
All the best,😉
Hi,
Hearing aid batteries on the low side again?
Shows how resolving your system is or should one say your "mind"?
Do whatever you like within your limitations, Joel, I can't care less, just don't hamper people with a bit more ambition than yourself, will you?
Show us you can let the RDH go and fly on your own wings, its high time for you to do so IMHO.
All the best,😉
Re: Re:Re: CHRISBs' PHONOPRE.
It took a lot less time to draw them... next time just mail me the scans -- or if your 'puter guy continues to turn them around so quick, it might be faster to snail-mail me photocopies 🙂
dave
fdegrove said:
It took a lot less time to draw them... next time just mail me the scans -- or if your 'puter guy continues to turn them around so quick, it might be faster to snail-mail me photocopies 🙂
dave
WOW...AGAIN...
Hi,
But I'll be rewarding you for your work, one way or an other Dave.
Mighty nice of you to offer this kind of service...I might take you up on it, whenever the creative juices get flowing again I'll remember your offer..in the mean time, if I can help you with anything I will, promise.
Morning stiffness, Brett?😉
I'd love to implement Allen Wrights' RIAA idea into this phono stage, it's probably simple enough even for my non-mathematical mind but I fail to see how to implement it correctly here.
Any additional info on calcs is welcomed...Thinking out loud...is this lack of corrective RIAA measure the reason why MC carts with a rising top end didn't bother me all that much?
Puzzling.
Cheers,😉
Hi,
But I'll be rewarding you for your work, one way or an other Dave.
Mighty nice of you to offer this kind of service...I might take you up on it, whenever the creative juices get flowing again I'll remember your offer..in the mean time, if I can help you with anything I will, promise.
Morning stiffness, Brett?😉
I'd love to implement Allen Wrights' RIAA idea into this phono stage, it's probably simple enough even for my non-mathematical mind but I fail to see how to implement it correctly here.
Any additional info on calcs is welcomed...Thinking out loud...is this lack of corrective RIAA measure the reason why MC carts with a rising top end didn't bother me all that much?
Puzzling.
Cheers,😉
Just a little thought...
Is there a typo in the drawing of Post #85? Should the series resistor from the first stage to the second actually be 100k rather than 100R?
The MC step-up seems familiar. Did I see an early version in Wireless World donkey's years ago?
Is there a typo in the drawing of Post #85? Should the series resistor from the first stage to the second actually be 100k rather than 100R?
The MC step-up seems familiar. Did I see an early version in Wireless World donkey's years ago?
TYPO!!!
Hi,
Oh dear, I do need a pair of glasses...🙁
EC8010 is absolutely correct the 100R resistor in the phono pre goining from the anode of the first triode halve just after the 47nF/400VDC must be 100K not 100R.
It is of utmost importance for the RIAA correction.
I'll update the circuit asap and repost it.
Actually it was inspired by Eisenson of Audio Dimension, a similar cicrcuit was published by Christer Oehrnell in HI-FI news & RECORD Reviev in the June 1983 issue.
Quite likely it was published in other magazines as well.
Thank you for spotting the error.
Cheers,😉
Hi,
Oh dear, I do need a pair of glasses...🙁
EC8010 is absolutely correct the 100R resistor in the phono pre goining from the anode of the first triode halve just after the 47nF/400VDC must be 100K not 100R.
It is of utmost importance for the RIAA correction.
I'll update the circuit asap and repost it.
Actually it was inspired by Eisenson of Audio Dimension, a similar cicrcuit was published by Christer Oehrnell in HI-FI news & RECORD Reviev in the June 1983 issue.
Quite likely it was published in other magazines as well.
Thank you for spotting the error.
Cheers,😉
Hi Frank
I seem to be a bit confused. Could you please let us know how you calculate the values for the riaa components. It seems to me the output resitance of the first stage should not matter for riaa accuracy in a feedback arrangement but i haven't really given it a good thought. If it does indeed matter than the cathode bypass on the first stage cannot be optional as it changes the output resistance of the stage.
cheers
peter
I seem to be a bit confused. Could you please let us know how you calculate the values for the riaa components. It seems to me the output resitance of the first stage should not matter for riaa accuracy in a feedback arrangement but i haven't really given it a good thought. If it does indeed matter than the cathode bypass on the first stage cannot be optional as it changes the output resistance of the stage.
cheers
peter
Re: WOW...AGAIN...
Frank,
Its actually pretty easy to implement Allen Wrights suggestion of an extra pole (or is that zero?). I don't have his article handy, but I believe his suggestion is to flatten the curve out at 50khz, instead of letting things drop forever.
To do that in your circuit you need to put a resistor in series with the 0.0033uf cap. A value of around 965 would do the trick. I believe the nearest standard value is 976, which should be fine for most folks.
---Gary
fdegrove said:
Frank,
Its actually pretty easy to implement Allen Wrights suggestion of an extra pole (or is that zero?). I don't have his article handy, but I believe his suggestion is to flatten the curve out at 50khz, instead of letting things drop forever.
To do that in your circuit you need to put a resistor in series with the 0.0033uf cap. A value of around 965 would do the trick. I believe the nearest standard value is 976, which should be fine for most folks.
---Gary
SOMEONE'S HAPPY...
Hi,
Gary,
Thanks, I think Dave and his buddy will be happy with that.
Correct, 976R is the nearest value from the E96 series.
Peter,
First and foremost, it's been ages since I looked at all that RIAA stuff.
Still, the first pole is formed by the 47nF and series R 100K, the next two are frequency dependent networks as you would do in a classic circuit, say a la Dyna or Marantz, the difference is that the signal is fedback from the anode of the second triode.
It does matter and in this incarnation of the circuit the cathode bypass is not optional.
The dotted lines had more to do with the value and nature of the caps.
See, at first I used 2.2uF Wima filmcaps for that...later on I fitted 4.7uF Roederstein MKP 1831s which sounded better and allowed for more extended bass response in conjunction with a 0.68uF iso the 0.47uF after the first anode.
You need a very quiet TT combo for that with a really dead tonearm or the woofer cones will flap like hell.
Cheers, 😉
Hi,
Gary,
Thanks, I think Dave and his buddy will be happy with that.
Correct, 976R is the nearest value from the E96 series.
Peter,
First and foremost, it's been ages since I looked at all that RIAA stuff.
Still, the first pole is formed by the 47nF and series R 100K, the next two are frequency dependent networks as you would do in a classic circuit, say a la Dyna or Marantz, the difference is that the signal is fedback from the anode of the second triode.
It does matter and in this incarnation of the circuit the cathode bypass is not optional.
The dotted lines had more to do with the value and nature of the caps.
See, at first I used 2.2uF Wima filmcaps for that...later on I fitted 4.7uF Roederstein MKP 1831s which sounded better and allowed for more extended bass response in conjunction with a 0.68uF iso the 0.47uF after the first anode.
You need a very quiet TT combo for that with a really dead tonearm or the woofer cones will flap like hell.
Cheers, 😉
Hi Frank
Is there a way to use ur linestage
as buffer in an active crossover? , ( Sallen Key )
or would that mess up the whole feedback thingie
of the White follower ?
cheers
Is there a way to use ur linestage
as buffer in an active crossover? , ( Sallen Key )
or would that mess up the whole feedback thingie
of the White follower ?
cheers
RE:RIAA.
Hi,
Truth be told, I am not remembering all the details myself.
Fact is though, this all pretty complex to explain mathematically.
This RIAA correction was done way back then together with a good friend of mine and it took us several months to get it right.
From what I remember, every component matters for the RIAA correction to fall into place, even the 1 Meg attenuator of the linestage...in short, not the kind of circuit you want to change component values with without upsetting it.
Almost everything is interactive.
From that perspective it is best to look at the whole circuit, the phono and line stage as a whole.
Taking all that into account a passive RIAA stage is peanuts compared to this.
We used an inverse RIAA network a la Hagtech to check it for accuracy and it came within +/- 0.2 dB.
I still have the diagram for that one, if you like I can e-mail it to you.
One person I can think of is able to refresh my memory is EC8010 or GaryB and no doubt other wizards.
I've been out of this kind of math for too long to be really helpful to you.
All I can say with certainty is that it works.No doubt in my mind there.
Any particular reason you want to reverse engineer it? Or are you just curious?
Expert comments are welcome,😉
Hi,
Truth be told, I am not remembering all the details myself.
Fact is though, this all pretty complex to explain mathematically.
This RIAA correction was done way back then together with a good friend of mine and it took us several months to get it right.
From what I remember, every component matters for the RIAA correction to fall into place, even the 1 Meg attenuator of the linestage...in short, not the kind of circuit you want to change component values with without upsetting it.
Almost everything is interactive.
From that perspective it is best to look at the whole circuit, the phono and line stage as a whole.
Taking all that into account a passive RIAA stage is peanuts compared to this.
We used an inverse RIAA network a la Hagtech to check it for accuracy and it came within +/- 0.2 dB.
I still have the diagram for that one, if you like I can e-mail it to you.
One person I can think of is able to refresh my memory is EC8010 or GaryB and no doubt other wizards.
I've been out of this kind of math for too long to be really helpful to you.
All I can say with certainty is that it works.No doubt in my mind there.
Any particular reason you want to reverse engineer it? Or are you just curious?
Expert comments are welcome,😉
I was really hoping you wouldn't say that, Frank...
The algebra for a feedback network is unpleasant. The paper to read is:
"On RIAA equalization networks" Stanley P Lipshitz. JAES. 1979. June. Volume 27. Number 7. pp458-481
What makes it even more unpleasant is that the equalisation is applied over an inverting amplifier with limited gain. Lipshitz gives equations for dealing with this problem, but they're not for the faint-hearted.
This is one of the reasons why I favour passive RIAA.
The algebra for a feedback network is unpleasant. The paper to read is:
"On RIAA equalization networks" Stanley P Lipshitz. JAES. 1979. June. Volume 27. Number 7. pp458-481
What makes it even more unpleasant is that the equalisation is applied over an inverting amplifier with limited gain. Lipshitz gives equations for dealing with this problem, but they're not for the faint-hearted.
This is one of the reasons why I favour passive RIAA.
SO SORRY...
Hi,
Purrrrcisely why I unconsciously have forgotten (read blocked) about all this material.
I'm sorry to have dragged you into this EC8010.
This kind of circuit goes to show how much I wanted to forget...and how much I lost already...as you made clear this is a major PITA...
Peter, I think you better take it at face value...
BTW, the 10 x 4.7 uF bypass caps are just my folly, 22uF will do fine if you want accurate RIAA from 20Hz upwards.
I've been playing with this circuit to get rid of the bypass caps and still maintain RIAA accuracy, no success so far...
Doing away with them speeds up transient response no end but at the expense of bass reponse...
No free lunch and way over my head there...
Cheers,😉
Hi,
Purrrrcisely why I unconsciously have forgotten (read blocked) about all this material.
I'm sorry to have dragged you into this EC8010.
This kind of circuit goes to show how much I wanted to forget...and how much I lost already...as you made clear this is a major PITA...
Peter, I think you better take it at face value...
BTW, the 10 x 4.7 uF bypass caps are just my folly, 22uF will do fine if you want accurate RIAA from 20Hz upwards.
I've been playing with this circuit to get rid of the bypass caps and still maintain RIAA accuracy, no success so far...
Doing away with them speeds up transient response no end but at the expense of bass reponse...
No free lunch and way over my head there...
Cheers,😉
RIAA calculations
Frank,
I agree with EC8010 - calculating the RIAA curve in a feedback network is a pain and I would never try to do it. I much prefer passive RIAA equalization.
I should also point out that my comments about adding Allen Wrights extra zero at 50khz applied to the RCA phono circuit that Dave included, not Frank's phono preamp. Analyzing this circuit is relatively straightforward.
For those who are really interested in more details on calculating RIAA eq, I scanned an old article from Audio Amateur and posted it on the following website:
http://joelist.free.fr/riaa_tube.pdf
---Gary
Frank,
I agree with EC8010 - calculating the RIAA curve in a feedback network is a pain and I would never try to do it. I much prefer passive RIAA equalization.
I should also point out that my comments about adding Allen Wrights extra zero at 50khz applied to the RCA phono circuit that Dave included, not Frank's phono preamp. Analyzing this circuit is relatively straightforward.
For those who are really interested in more details on calculating RIAA eq, I scanned an old article from Audio Amateur and posted it on the following website:
http://joelist.free.fr/riaa_tube.pdf
---Gary
RE:RIAA CALCULATIONS.
Hi,
Thank you Gary for chipping in...
I'll be the last person on earth to disagree, I suppose we just got overly ambitious on that one...
Relative being the keyword...but, yes it's much more straightforward and also much more documented...
Thanks Gary,😉
Hi,
Thank you Gary for chipping in...
I'll be the last person on earth to disagree, I suppose we just got overly ambitious on that one...
Relative being the keyword...but, yes it's much more straightforward and also much more documented...
Thanks Gary,😉