Age of records used is also important as the plasticisers migrate thereby causing the surface to become much changed from it's original state.
1dB/div.
Here you can find published measurements of many cartridges:
Stereo Pickups & Phono Cartridges : 1958 - today – Stereotonabnehmer
Here you can find published measurements of many cartridges:
Stereo Pickups & Phono Cartridges : 1958 - today – Stereotonabnehmer
Another feeble attempt to make LP playback seem worse than it really is.
Here is the factory calibration for a Denon DL103 I have. As most will know, this is one of the lowest cost MC cartridges man can buy. It is a fine professional product for all that, even if not as wonderful as my Lyras.
The curves for this cheap cartridge show none of the lumpiness in your sketch, but a gentle 1dB softening in the lower treble - ideal, in other words for matching with a wide range of programme material, with minimized risk of sounding shrieky. It is designed for use in radio stations, after all.
Attachments
PMA and Rod, you are both right. If you are sloppy, and let things get out of hand, with poor RIAA EQ, indifferent loading with MM cartridges, set-up, etc., you can get some pretty lousy curves. As far as the V15 MK4 is concerned: Please note the approximately 14K peak. My now business partner, bought this cartridge in the early 1960's at my suggestion. We could hear that peak at 14KHz as extra noise, when playing a record.
Then note the Ortofon SPU, a cartridge that I switched to in late 1965: It has a much smoother frequency response, but something happened to the lows, in the graph. I suspect poor arm match and damping, but the transformer MAY have something to do with it as well. Why do you think I set myself to the task of designing Ortrofon cartridge replacements with solid state, back as far as 1967?
On the other hand, manufacturers often LIE with their graphs, AND you cannot always depend on them. However, the Denon graph looks OK, as would the SUPEX, EMT, or Ortofon cartridges that I personally measured as early as 1974, with B&K lab records and equipment, out to 40K or so.
I like Lyra's also, why? I don't know.
Then note the Ortofon SPU, a cartridge that I switched to in late 1965: It has a much smoother frequency response, but something happened to the lows, in the graph. I suspect poor arm match and damping, but the transformer MAY have something to do with it as well. Why do you think I set myself to the task of designing Ortrofon cartridge replacements with solid state, back as far as 1967?
On the other hand, manufacturers often LIE with their graphs, AND you cannot always depend on them. However, the Denon graph looks OK, as would the SUPEX, EMT, or Ortofon cartridges that I personally measured as early as 1974, with B&K lab records and equipment, out to 40K or so.
I like Lyra's also, why? I don't know.
Note the SADDLE response of the DENNON graph. This is due to scanning loss of the stylus to vinyl interface and is RADIUS sensitive.
In truth, minor deviations like this, are relatively meaningless, and generally not really notable. However, in this world of precision digital measurement, it is made much of, just like in the USA, the 'Jack in the Box' fast food commercial emphasizes low cost, when comparing to home made food preparation. The 'taste difference' is ignored.
Same with digital, as it is possible to get flat measured responses, even if the transient response is completely destroyed in the process.
In truth, minor deviations like this, are relatively meaningless, and generally not really notable. However, in this world of precision digital measurement, it is made much of, just like in the USA, the 'Jack in the Box' fast food commercial emphasizes low cost, when comparing to home made food preparation. The 'taste difference' is ignored.
Same with digital, as it is possible to get flat measured responses, even if the transient response is completely destroyed in the process.
The Elac and Shure 212 response curves look particularly impressive. The problem with the Elac is its low compliance of only 4 x 10 -6. Note that even today, the Denon DL 103 MC cartridge requires 2.5 grams of tracking force.
The 1965 Ortofon required 2 g of force while the Shure V15 and ADC required 60% less force. It's hard to say what the Ortofon SPU-TE was. It's output was much higher than typical MC cartridges for its day and its FR much flatter. Clearly the ADC was the best of the lot.
The manufacturer's claimed FR curve for Shure V15 type IV is very impressive. Tracking force is only .75 to 1 G
www.shure.com/idc/groups/tech_pubs/%4...
Shure got a flatter response in some of is later phono cartridges, because it effectively filled the void with a response boost due to the cartridge's resonance characteristics. The optimum tracking force of the LATEST Shure cartridge, still available today, is 1.25g. Please, get up to date. The RECOMMENDED tracking force of the Ortofon MC20II, similar to the cartridge that I measured in 1978, was 1.75 grams , a silly 1/2 gr difference. Compliance is very important in association with recommended tracking weight. However, many low compliance cartridges do indeed sound better to most serious audiophiles than Shure cartridges with their high compliance.
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Is everyone ready to go on to design the very simple volkspreamp? Joachim and I are ready, any time you are.
Oh, are we ready!
Are all modern-day problems with pre-amps uncovered? For instance the gain gap between analog and digital sources. Analog sources need 10-20 dB more gain than digital sources for "full" output. The usual compromise is to handle this in the volume control, often resulting in bad channel tracking and bad adjustment resolution for high level sources.
What are the alternatives for adjusting volume?
Do we need a balance control?
How to implement the input selector?
Output muting?
Balanced or unbalanced?
PSU
etc.
Block schematic first, perhaps?
Are all modern-day problems with pre-amps uncovered? For instance the gain gap between analog and digital sources. Analog sources need 10-20 dB more gain than digital sources for "full" output. The usual compromise is to handle this in the volume control, often resulting in bad channel tracking and bad adjustment resolution for high level sources.
What are the alternatives for adjusting volume?
Do we need a balance control?
How to implement the input selector?
Output muting?
Balanced or unbalanced?
PSU
etc.
Block schematic first, perhaps?
We have NOTHING except the base minimal effort. I would like to get through that, as a design exercise. IF you want everything else, buy a Parasound or its equivalent.
If you run real fast, you can hope it won't catch up to you.
As Satchel Paige famously said: "don't look back, something might be gaining on you."
Separate gain controls for all inputs and gain stages for each low level input before the input selector. It isn't novel. Many preamps had them for phono inputs a long time ago. I think MacIntosh had them for all inputs way back. Even the first AR amplifier had one for its phono input.
Some so called "purists" think any circuit element that isn't absolutely necessary should be eliminated. If they only knew how many of them a signal goes through before the recording they buy is marketed.
I am a little late here because i had something important to do. So should we agree on using the OPA4134 ?
One idea whould be to take away the servo and use the two Opamps that are free now for line level. Instead of the servo we could use an elcap in series with the 600 Ohm feedback resistor. For economy i whould use a Pannasonic FC or FM. Nichicon KZ and Elna Silmic 2 are a bit better but also a bit more expensive.
We could substitute the 600 Ohm resistor with a 500 Ohm resistor plus a 500 Ohm trimmer for adjusting level so that phono and line have the same volume. I personally whould go for seperate volume controls on both channels, then we have the balance control for free but less convenience. I had a DNM preamp for many years that has the same feature and after a while i got acustomed to that. What about a mono switch ?
I whould like to have one out of a lot of reasons.
One idea whould be to take away the servo and use the two Opamps that are free now for line level. Instead of the servo we could use an elcap in series with the 600 Ohm feedback resistor. For economy i whould use a Pannasonic FC or FM. Nichicon KZ and Elna Silmic 2 are a bit better but also a bit more expensive.
We could substitute the 600 Ohm resistor with a 500 Ohm resistor plus a 500 Ohm trimmer for adjusting level so that phono and line have the same volume. I personally whould go for seperate volume controls on both channels, then we have the balance control for free but less convenience. I had a DNM preamp for many years that has the same feature and after a while i got acustomed to that. What about a mono switch ?
I whould like to have one out of a lot of reasons.
I have now corrected the values in the RIAA to 1/3 of the original values. The 500 Ohm feedback resistor could be raised to 600 Ohm so that the Opamp never has to drive less then 600 Ohm. I have a safety cap in series with the linestage. You never know if the input signal has a DC content. I could not help to do a little trick in the line stage. It has nearly zero output impedance but can drive a capacitive load.
I have not shown this circuit to JC so please correct me if i did something wrong. I also whould apreciate any improvements. Ok, this circuit has now 2 caps in the signal path.
I have not shown this circuit to JC so please correct me if i did something wrong. I also whould apreciate any improvements. Ok, this circuit has now 2 caps in the signal path.
What about to set the signal output level like from a CDP?
Pro: using a passive pre - maybe with a TVC - or using a line stage with gain = 1, in other words only a buffer stage.
Pro: using a passive pre - maybe with a TVC - or using a line stage with gain = 1, in other words only a buffer stage.
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