Ear piercing setup...
Three years...
and I'm wondering again.
Finally got a new cart wich was advised as a very good match for ma Thorens TD 318: an Ortofon OM 20 Super.
But it is way too bright, just enough not to play any record. Other sources sounds just fine on amp/speakers setup.
So I wonder on both ends of the Pacific: how and where to exaclty load it? Original post features a 100K, no cap, Scafas' circuit a no-value resistor, no cap.
It's there were I put what I want, say 47k/100pF as it is right now?
And finally, the other end, no driving difficulties for the Pacific with my passive 10k preamp?
My CD sounds "vinyl" beside it...
Thanks
Matthieu
edit: for TT gurus, in case I've done it wrong:
Cables capacitance: 98.8 and 95.7pF
VTF: 1.35g
VTA: 0°
Load: 47k/100pf
Three years...
and I'm wondering again.
Finally got a new cart wich was advised as a very good match for ma Thorens TD 318: an Ortofon OM 20 Super.
But it is way too bright, just enough not to play any record. Other sources sounds just fine on amp/speakers setup.
So I wonder on both ends of the Pacific: how and where to exaclty load it? Original post features a 100K, no cap, Scafas' circuit a no-value resistor, no cap.
It's there were I put what I want, say 47k/100pF as it is right now?
And finally, the other end, no driving difficulties for the Pacific with my passive 10k preamp?
My CD sounds "vinyl" beside it...
Thanks
Matthieu
edit: for TT gurus, in case I've done it wrong:
Cables capacitance: 98.8 and 95.7pF
VTF: 1.35g
VTA: 0°
Load: 47k/100pf
The technical data for the Ortofon indicate that it wants a higher capacitance on the input:
Type: MM
Fixing: Half-inch mount
Output voltage: 4,0mV bei 1kHz, 5cm/sec.
Amplifier-connection: Phono MM
Frequency range: 20-27.000Hz
Frequency range: 20-20.000Hz +2dB/-1dB
Compliance: 25µm/mN (lateral)
Material: diamond, nude
Stylus type: elliptical r/R 8/18µm
Tracking force range: 1,0-1,5g
Tracking force, recommended: 1,25g
Recommended load capacitance: 200-500pF
Weight: 2,5g (5g)
So double, triple or quadruple your current load capacitance. Also make sure that your tracking is correct.
Type: MM
Fixing: Half-inch mount
Output voltage: 4,0mV bei 1kHz, 5cm/sec.
Amplifier-connection: Phono MM
Frequency range: 20-27.000Hz
Frequency range: 20-20.000Hz +2dB/-1dB
Compliance: 25µm/mN (lateral)
Material: diamond, nude
Stylus type: elliptical r/R 8/18µm
Tracking force range: 1,0-1,5g
Tracking force, recommended: 1,25g
Recommended load capacitance: 200-500pF
Weight: 2,5g (5g)
So double, triple or quadruple your current load capacitance. Also make sure that your tracking is correct.
I've actually used that cartridge with that phono stage (actually the boozehound phono) and a passive preamp into a tripath amp (and later a pass F5).
Here's a few of my observations:
The Pacific topology has a lot of input capacitance into the first stage...I don't remember the specifics but I think it's around 200pf. Add your cables capacitance to this. Adding 100pf may be OK but I don't think input capacitance is your issue.
Also, the pacific lacks a buffer on output which is fine, but you are trying to drive a pot with it and then into an amp. In my case, it didn't work well. I added a buffer and it was way better. This may depend on what amp is after your passive and how long the interconnects are.
Also, I found the OM20 bright and airy. Images really well and a big soundstage but it is not rich or bassy. More VTF will help but will make it less airy. Also, you may want to lower the tonearm a mm or two.
Also, if you load it at 33K it might help. But I think in some ways, this is the character of the cartridge. I would say it's more flat than bright but you may be coming from a cartridge with more bass.
If you look at the Salas phono he has perfected this design. I am using one now and it is one of the best things I have ever built. Look at the output buffer...the cascoded input...all ways to remove the shortcomings of the le pacific. Maybe you can incorporate some of these things in yours?
Here's a few of my observations:
The Pacific topology has a lot of input capacitance into the first stage...I don't remember the specifics but I think it's around 200pf. Add your cables capacitance to this. Adding 100pf may be OK but I don't think input capacitance is your issue.
Also, the pacific lacks a buffer on output which is fine, but you are trying to drive a pot with it and then into an amp. In my case, it didn't work well. I added a buffer and it was way better. This may depend on what amp is after your passive and how long the interconnects are.
Also, I found the OM20 bright and airy. Images really well and a big soundstage but it is not rich or bassy. More VTF will help but will make it less airy. Also, you may want to lower the tonearm a mm or two.
Also, if you load it at 33K it might help. But I think in some ways, this is the character of the cartridge. I would say it's more flat than bright but you may be coming from a cartridge with more bass.
If you look at the Salas phono he has perfected this design. I am using one now and it is one of the best things I have ever built. Look at the output buffer...the cascoded input...all ways to remove the shortcomings of the le pacific. Maybe you can incorporate some of these things in yours?
Hi guys,
thanks fortitudine for cart info, I'll play in that capacitance window.
Hikari I'll try that, and the 40k also recommended, at the end it is clear; not the right RIAA pre here.
I've had a look at Sala's one, great job as usual, but even with a buffer he stands great performance driving down to... 20k :'( no wonder my 10k is a burden to my Pacific!
And it's folowed by a pair of UCD400.
Maybe time for a new pre phono project...
thanks fortitudine for cart info, I'll play in that capacitance window.
Hikari I'll try that, and the 40k also recommended, at the end it is clear; not the right RIAA pre here.
I've had a look at Sala's one, great job as usual, but even with a buffer he stands great performance driving down to... 20k :'( no wonder my 10k is a burden to my Pacific!
And it's folowed by a pair of UCD400.
Maybe time for a new pre phono project...
I think you should investigate buffered vol pots/passive preamps. The pass b1 would work well. In my experience, vinyl and passive preamps don't mix well though. Or build a jfet boz..run off batteries it's a really cheap experiment.
I gave up on passives even when using the pass f5 (100k input impedence). Iam not familiar with the hypex stuff but every amp I have used lacks dynamics and weight with a passive in front of it. Especially with a phono preamps lower current/ability to drive.
An alternative would be to add a buffer like salas did on the output. You will need another pair of 2sk170. An extreme alternative would be a mosfet buffer (lots of schematics out there for headphone amps) on the output.
Actually, the pacific I had was quite good run off batteries. Better than all the commercial stuff I tried. It worked best with a denon high mc cart which makes sense since it doesn't care about the input capacitance. I am not sure your issue is so much the phono stage.
One thing...a impedence mismatch or lack of ability to drive the amp would probably result in a lack of dynamics and a dull hi end. Which is not what you are describing. Also, I would say the pacific phono sounds warmer and duller than some other phono stages which is also not what you are describing. You sure your phono amp is working correctly?
I gave up on passives even when using the pass f5 (100k input impedence). Iam not familiar with the hypex stuff but every amp I have used lacks dynamics and weight with a passive in front of it. Especially with a phono preamps lower current/ability to drive.
An alternative would be to add a buffer like salas did on the output. You will need another pair of 2sk170. An extreme alternative would be a mosfet buffer (lots of schematics out there for headphone amps) on the output.
Actually, the pacific I had was quite good run off batteries. Better than all the commercial stuff I tried. It worked best with a denon high mc cart which makes sense since it doesn't care about the input capacitance. I am not sure your issue is so much the phono stage.
One thing...a impedence mismatch or lack of ability to drive the amp would probably result in a lack of dynamics and a dull hi end. Which is not what you are describing. Also, I would say the pacific phono sounds warmer and duller than some other phono stages which is also not what you are describing. You sure your phono amp is working correctly?
What are your speakers (for example)? I think - I know the pacific - your problems are the other stuff - if the pacific is build well. You have to tune a Thorens 318, the pickup is to decouple, change the origin wire, use very fine wire, no diameter - complete (pickup - amp)! No cinch (katastrophe in "high tones", exacter: in resolution!) ...
Do build a good little se-amp, no unnecessary amps, no complementer-pp! One or two stages (in my case the pacific drives a se-poweramp!), use good fullrange, do not use lace, do not use big diameters, do not use tweeters
...and so on.
Good luck and enjoy your hobby,-)
Do build a good little se-amp, no unnecessary amps, no complementer-pp! One or two stages (in my case the pacific drives a se-poweramp!), use good fullrange, do not use lace, do not use big diameters, do not use tweeters
...and so on.
Good luck and enjoy your hobby,-)
Apparently UCD400 come with unbuffered and buffered inputs?
If you are using or only have the unbuffered input it appears to be 1.8K impedance...I don't know if putting a 10K pot is a good idea.
Would be easy enough to convert your phono to what Salas has given us. What a nice guy.
If you are using or only have the unbuffered input it appears to be 1.8K impedance...I don't know if putting a 10K pot is a good idea.
Would be easy enough to convert your phono to what Salas has given us. What a nice guy.
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Hi there,
thanks all for helping.
Salas I may try your circuit on my Pacific, easy enough. Always around and full of energy! Maybe living in Olympus...
Cumbb, I will not go that far, I am lossing some interest in messing on the hardware side, even if I must admit I have open baffle ready for my own town maker: Supravox...
And to stay a bit oot, Hikari I think I am OK with my 10k pot as my UCD400 is buffered, 100k input Z. Even if I've just found out that the datasheet of my UCD calls for 7k max... close enough I guess, my DACs, tuner (ok FM is 15kHz max) and other sources sound just great with my UCD400HG (right now only SE inputs, balanced inputs soon), then my old studio monitors in a pair of JBL 4313B (don't mix with the 4311 wich are not neutral at all). As studio monitors and fine ones, they sadly forgive nothing. I really think this sound issue is in the phono pre/RIAA stage.
Will go Salas and be back. Thanks guys!
thanks all for helping.
Salas I may try your circuit on my Pacific, easy enough. Always around and full of energy! Maybe living in Olympus...
Cumbb, I will not go that far, I am lossing some interest in messing on the hardware side, even if I must admit I have open baffle ready for my own town maker: Supravox...
And to stay a bit oot, Hikari I think I am OK with my 10k pot as my UCD400 is buffered, 100k input Z. Even if I've just found out that the datasheet of my UCD calls for 7k max... close enough I guess, my DACs, tuner (ok FM is 15kHz max) and other sources sound just great with my UCD400HG (right now only SE inputs, balanced inputs soon), then my old studio monitors in a pair of JBL 4313B (don't mix with the 4311 wich are not neutral at all). As studio monitors and fine ones, they sadly forgive nothing. I really think this sound issue is in the phono pre/RIAA stage.
Will go Salas and be back. Thanks guys!
Salas said:
And loaded at 550pF it is far over that " bright" side (I've been advised of 100/200pF) of my "bright" cart... sounds logic now. Add to that the 10K passive...
And my matched 6.5mA and another matched 10.3mA... not the 8.5 needed... you guys are OK with me, it's the wrong way that Pacific for me, isn't it?
I know that will make you sooooo sad, but I think of an opamp based design right now. I need to listen to my music, I got spare parts...
Ultimately it is not the best solution for you due to input capacitance and using an MM. The weak output drive capability can become yet another problem of course. Although the revision I showed you rectifies the bright RIAA curve of the original and weighs the gain structure better. It can drive >15K with relative ease and you could in the meantime try your weaker FETS at the input and the stronger at the output where is a trimmer. You may keep any RC filters on the rail, they do good. Maybe it will play better till you decide for another circuit or to use something like a DENON DL-110.
Hi all,
done that new version.
Last question, how to fine tune the output trimmers? By hear or something to measure? Anyway, set at 40R, it does better as for sibilance in that it's at a bearable level now, maybe an extra touch of (shy) bass also. Overall it's bright, too bright even if this is really the only flaw, everything else is great... but it will stay until I can start somthing new. (seen Salas Folded one in sell here but not a single euro to but it, sadly... ).
BTW, thanks all for the help and explanations!
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Turn the R8 trimmers for 9VDC on Q2's drain. Hunt for the best possible balance by adjusting the 100K R1 cartridge load trimmers first. 10k-100k by 10k together steps. If that is not enough, add nF little by little with small parallel capacitor(s) under C3s until you will subjectively balance out the MM cartridge HF resonance happening on the JFET Miller highish input capacitance. If ever with a high MC model revert to 33nF which is OK curve for a low inductance cart that will not adversely interact with the input stage. Looks nice as hand craft BTW.
Near to sound "right"!
Thanks again Salas,
maybe I can find all infos in one of your threads but I've not enough life expectancy to read the thousands posts in there!
I've adjusted trimmers to get the 9V and played a bit with input load (and added socket prior to extra capacitance tests at C3) and yes it is leaning toward neutrality now. Can enjoy my records! =) Time to celebrate Nike!
As I am using a single regulated supply (Using 3-pin regulators off-piste: part 2) I've added 100µF on each channel to get better separation, hope that's OK. Can add more of my Panasonic FM if anyone find it better LF-wise...
Thanks again Salas,
maybe I can find all infos in one of your threads but I've not enough life expectancy to read the thousands posts in there!
I've adjusted trimmers to get the 9V and played a bit with input load (and added socket prior to extra capacitance tests at C3) and yes it is leaning toward neutrality now. Can enjoy my records! =) Time to celebrate Nike!
As I am using a single regulated supply (Using 3-pin regulators off-piste: part 2) I've added 100µF on each channel to get better separation, hope that's OK. Can add more of my Panasonic FM if anyone find it better LF-wise...
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Congratulations. You would not find in my threads specifically as such, its a special revision of your circuit and a method to help you solve the chronic treblenchitis situation.
Its good you added local reservoir per channel after a common capacitor multiplier voltage source. Because highish and bumpy output impedance is its downside. You could just add 100 Ohm series resistance before each of those capacitors for little more separation and filtering. Better don't ask big capacitance charge current from the small transistor. Using an SMPS externally?
Its good you added local reservoir per channel after a common capacitor multiplier voltage source. Because highish and bumpy output impedance is its downside. You could just add 100 Ohm series resistance before each of those capacitors for little more separation and filtering. Better don't ask big capacitance charge current from the small transistor. Using an SMPS externally?
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