I am a convert to vinyl, having long believed CD's were superior. I was wrong. So I am digging out all my old phono stuff and am about to buy a good MC cartridge.
I have an old Marcof PPA-1 grounded base MC pre-amp Anyone with experience with them? I think I am going to try it with a Denon 103 and see how it sounds. I used this many years ago and don't really recall what is sounded like. I no longer have transformers, except for some useless Danish JS ones with 244:1 gain/1.5 Ohm input impedance and I can't remember if I ever used them (It's been that long).
I know there is a difference of opinion regarding amps vs trans.
Here is an interesting exposition from the creator of the circuitry
http://users.ece.gatech.edu/mleach/headamp/
I have an old Marcof PPA-1 grounded base MC pre-amp Anyone with experience with them? I think I am going to try it with a Denon 103 and see how it sounds. I used this many years ago and don't really recall what is sounded like. I no longer have transformers, except for some useless Danish JS ones with 244:1 gain/1.5 Ohm input impedance and I can't remember if I ever used them (It's been that long).
I know there is a difference of opinion regarding amps vs trans.
Here is an interesting exposition from the creator of the circuitry
http://users.ece.gatech.edu/mleach/headamp/
The JS trafos are not useless. You will not find a finer trafo at any price.
They are not 244:1 or 1:244. They are 1:20. There are a few step-up trafos with higher gain than that. Unless used for mic preamps, they should be avoided since frequency response decreases.
Having that said, there's no use for step-up devices for sold-state gear. Not to mention that the JS trafos might have too high gain for the DL-103. Denon's step-up trafos are 1:13, I believe.
I would look into the Phonoclone on this forum. It's simple and cheap to build and I don't think you can make a better ss phono stage.
They are not 244:1 or 1:244. They are 1:20. There are a few step-up trafos with higher gain than that. Unless used for mic preamps, they should be avoided since frequency response decreases.
Having that said, there's no use for step-up devices for sold-state gear. Not to mention that the JS trafos might have too high gain for the DL-103. Denon's step-up trafos are 1:13, I believe.
I would look into the Phonoclone on this forum. It's simple and cheap to build and I don't think you can make a better ss phono stage.
My JS tannies are No. 75s, and have marked on them the impedance (1.5 Ohms) and the turns ratio (1:244). They are not the No. 251's that are used with MC cartdridges. Their gain and input impedance are not suitable for an MC cartridge.
The phonclone is a seems to be a low gain preamp using an op amp more suitable for an MM cartridges.
The phonclone is a seems to be a low gain preamp using an op amp more suitable for an MM cartridges.
rdr said:
OK. Then it is useless.
rdr said:
No, it's not for MM carts and it has two opamps.
http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho4.html
rdr-
I think you have a better chance of someone being familiar with this circuit if you posted it in the solid state forum. It's not that it's in the wrong place here, it's just that this forum doesn't get near the traffic.
FWIW, Leach's stuff is generally good from what I know about it, however, you need to realize that there has been a quiet revolution of all things vinyl in that last couple of decades(and the technology that can be applied, the quality of the opamps in the phono clone for example). I have found that a great many of my perceived "truths" has had to be re-evaluated when I got back into it a couple of years ago...generally the quality of whats available has improved by an order or two( at least what's available to the DIY'er).
-Casey
I think you have a better chance of someone being familiar with this circuit if you posted it in the solid state forum. It's not that it's in the wrong place here, it's just that this forum doesn't get near the traffic.
FWIW, Leach's stuff is generally good from what I know about it, however, you need to realize that there has been a quiet revolution of all things vinyl in that last couple of decades(and the technology that can be applied, the quality of the opamps in the phono clone for example). I have found that a great many of my perceived "truths" has had to be re-evaluated when I got back into it a couple of years ago...generally the quality of whats available has improved by an order or two( at least what's available to the DIY'er).
-Casey
Just make sure to change R2 to 5k6 or so. 1k5 will only give the DL-103 60-65db gain.
As I understand it, the OP637 benefits from biasing, whereas the AD797 and many (most?) others don't. So adding a buffer should not necessarily make much of a difference, if any. If I understand it correct, that is. The only reason I can see to use anything other than the OPA37 is the slew rate. The AD815 will not work with this circuit, but would otherwise have been an interesting alternative.
As I understand it, the OP637 benefits from biasing, whereas the AD797 and many (most?) others don't. So adding a buffer should not necessarily make much of a difference, if any. If I understand it correct, that is. The only reason I can see to use anything other than the OPA37 is the slew rate. The AD815 will not work with this circuit, but would otherwise have been an interesting alternative.
Hi,
the OPA637 is definitively a fine OP, but it´s by far not the best choice for an MC-head amp! As a FET-type its noise is lowest with high impedance sources (>several kOhms), which an MC-Pickup isn´t. This excludes it as the prime input OP of the phonoclone. Since in the second stage the RIAA feedback places the OP into noisegains <5, the OPA637 can´t be used in this stage either without additional compensation.
The OPA37 on the other hand is as a low voltage-noise bipolar OP and the better choice for Mid- to High-Output MCs. The best noise performance is exhibited with source resistances ~400Ohms. Md- and Low-output MCs will be better run into a AD797 or LT1115 which´s noise performance is best with source resistancec ~200Ohms. The AD797 can supply loads of current, so the minimum load resistance could be as low as 300Ohms (R3). Reducing the resistance values reduces noise contribution of the resistors (thermal noise) and therefore reduces the noise contribution of the whole second stage!
Since the first gain stage is the dominant one with regard to noise the OP27 is a good choice for the second stage.
jauu
Calvin
the OPA637 is definitively a fine OP, but it´s by far not the best choice for an MC-head amp! As a FET-type its noise is lowest with high impedance sources (>several kOhms), which an MC-Pickup isn´t. This excludes it as the prime input OP of the phonoclone. Since in the second stage the RIAA feedback places the OP into noisegains <5, the OPA637 can´t be used in this stage either without additional compensation.
The OPA37 on the other hand is as a low voltage-noise bipolar OP and the better choice for Mid- to High-Output MCs. The best noise performance is exhibited with source resistances ~400Ohms. Md- and Low-output MCs will be better run into a AD797 or LT1115 which´s noise performance is best with source resistancec ~200Ohms. The AD797 can supply loads of current, so the minimum load resistance could be as low as 300Ohms (R3). Reducing the resistance values reduces noise contribution of the resistors (thermal noise) and therefore reduces the noise contribution of the whole second stage!
Since the first gain stage is the dominant one with regard to noise the OP27 is a good choice for the second stage.
jauu
Calvin
Rummaging around I finally found my old Denon DL-103D. This brings back memories of great sound. It has a broken stylus, as usual with all my un-childproofed stuff. Is it possible to get a stylus or get this repaired?
Calvin-
The AD797 looks good too. These are all cheap enough to be auditioning them. The Denon 103's have an internal impedance of ~ 50 ohms.
Calvin-
The AD797 looks good too. These are all cheap enough to be auditioning them. The Denon 103's have an internal impedance of ~ 50 ohms.
rdr-
Yes. The "Needle Doctor" offers the Garrott Brothers retipping service, Google "cartridge reipping service" for other options. Retipping your "D" will cost about the same as buying a new "R", but, many consider the "D" to be superior..it has a much lower tracking force requirement for one.
Here is a comparison chart of the various 103 "flavors"
-Casey
Yes. The "Needle Doctor" offers the Garrott Brothers retipping service, Google "cartridge reipping service" for other options. Retipping your "D" will cost about the same as buying a new "R", but, many consider the "D" to be superior..it has a much lower tracking force requirement for one.
Here is a comparison chart of the various 103 "flavors"
-Casey
I am embarking on the research on current sensing MC amps. There is a lot of stuff to wade through. I wish there was a current synopsis somewhere since op amps have evolved beyond the 5 year old discussions I am wading through.
I wonder if my cantileverless DL-103D really would work as a feedback element with say a DL-103 or Dl-103S. Do they have the same coils and differ only in magnets and/or cantilever tips? Even if the coils are different I would expect some similarity in the non-linearities and so it could work to some extent.
Looks like I'll wade in and build this on a prototype board so I can play around. I'll try to report back, but as this will be a spare time project, it will be a while.
I wonder if my cantileverless DL-103D really would work as a feedback element with say a DL-103 or Dl-103S. Do they have the same coils and differ only in magnets and/or cantilever tips? Even if the coils are different I would expect some similarity in the non-linearities and so it could work to some extent.
Looks like I'll wade in and build this on a prototype board so I can play around. I'll try to report back, but as this will be a spare time project, it will be a while.
You guys should try getting op2228 samples... I put mine into a VSPS which I changed slightly to have a better little better PSU stage, and of course you can't get away without decoupling like the standard VSPS.
Beautifull improvement, I had opa2132 in there before and an NE5552 before that... It plays fine for a while before goig into oscilation on th e standard VSPS without decoupling caps on the power pins, so if you have something similar a quick swapout test should convince you to dig out the old soldering iron and make some mods. I went as fas a new PCBs.
Beautifull improvement, I had opa2132 in there before and an NE5552 before that... It plays fine for a while before goig into oscilation on th e standard VSPS without decoupling caps on the power pins, so if you have something similar a quick swapout test should convince you to dig out the old soldering iron and make some mods. I went as fas a new PCBs.
Poor psrr? I would expect that to be good on all modern opamps. But then, by good specs I only looked at the summary on the AD site. I wouldn't know what is good in most areas. I have a few DAC chip questions for the digital forum because I don't know how to read or interpret certain data.
Oscillation is something I would worry about as well. I'm a vinyl junkie and I cannot understand what people hope to find in their albums the 45MHz bandwidth and 100db s/n ratio of the OPA37 can't give them. There's the matter of slew rate. But that's it.
Granted, I haven't compared different opamps. Until I have, I have no option but to remain skeptic about this spec race.
Oscillation is something I would worry about as well. I'm a vinyl junkie and I cannot understand what people hope to find in their albums the 45MHz bandwidth and 100db s/n ratio of the OPA37 can't give them. There's the matter of slew rate. But that's it.
Granted, I haven't compared different opamps. Until I have, I have no option but to remain skeptic about this spec race.
I'm not talking about the AD811, which I know nothing about. I'm talking about the likes of the AD797 and people who say the OPA37 isn't good enough, like if audio somehow was not the low-bandwidth world it has always been.
I'm talking about opamps made for high-bandwidth applications. I'm talking about opamps that require bypass caps. I'm talking about opamps "designed to oscillate." I'm talking about about opamps with "self-defeating specs."
I'm talking about opamps made for high-bandwidth applications. I'm talking about opamps that require bypass caps. I'm talking about opamps "designed to oscillate." I'm talking about about opamps with "self-defeating specs."
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