thanks. Do you think you want to take this design from here and research the high gain Jfet and adjust it around that or from MiiB's design?
I would love your and MiiB's inputs in this. I would like to continue with a path that everybody here likes as well.
Yes I had listened to several models from the later 90's with Music Fidelity and Audio Note mailny.
I really, really loved their wide soundstage and warm bass.
I wanted to buy one pair back then, but at that time they were simply too expensive for me.
Sound was pretty detailed never hursh, a very very nice speaker.
Congratulation for the hard work you had put on it.
EDIT: I also always thought the wood job just looked extremely nice. Intreresting about bamboo wood. Dynavector 1T the top one uses the same type of wood, which makes me thing the choice of it is very, very interesting.
Yes, Bamboo is a good sounding material.
MiiB is leaving for Denver so he may not be able to contribute much at the moment.
First you have to decide if you want fully bal-in, bal-out.
Post 200 has that feature. In simulation it is extremely low distortion but both sides have to be matched to 0.1% or better.
I asume that you want J-Fets so the circuit has to be modified. That is not a big deal.
When you decide on the one shot RIAA with high Gm devices that schematic has to be modified too for balanced out. That is what i would do, to modify the one shot for fully balanced.
MiiB is leaving for Denver so he may not be able to contribute much at the moment.
First you have to decide if you want fully bal-in, bal-out.
Post 200 has that feature. In simulation it is extremely low distortion but both sides have to be matched to 0.1% or better.
I asume that you want J-Fets so the circuit has to be modified. That is not a big deal.
When you decide on the one shot RIAA with high Gm devices that schematic has to be modified too for balanced out. That is what i would do, to modify the one shot for fully balanced.
Here is the super low noise J-fet i talked about :InterFET Corp. Page Selector - IF3602 datasheet
It has a rather high input capacitance of 300pF. On the other hand if you parallel 8 x 2SK170 the input capacitance gets high too. This can lead to oscillation.
That can be solved with 1uH coils at the input.
It has a rather high input capacitance of 300pF. On the other hand if you parallel 8 x 2SK170 the input capacitance gets high too. This can lead to oscillation.
That can be solved with 1uH coils at the input.
wow that is great device, although input capacitance is considerably high.
Usually it can be lowered by a factor of 2 I believe by simply cascoding it, but still 150pF of capacitance won't cause any serious roll off, since for a medium 20 ohm impedance of the coil, -3dB cut off is still way, way beyond audible.
Question: post 200 is not using the "boosting ELCAP" or my eyes are not working properly today?
Thanks Joachim for those links.
Differential FE and differential VAS. Too bad it requires high compensation to make it stable.
Using this topology though, wouldn't allow the current or strans-Z RIAA to be used.
One thing I envision for this phono is a paralleled RIAA Paradise style.
What are is your take on this?
Differential FE and differential VAS. Too bad it requires high compensation to make it stable.
Using this topology though, wouldn't allow the current or strans-Z RIAA to be used.
One thing I envision for this phono is a paralleled RIAA Paradise style.
What are is your take on this?
Question on your comment:
a) if I modify circuit post 200 with Jfet, don't we drop down on gain like on the original schematic here?
I don't necessary dislike BJTs it is just that the input offset kind of make me worried at start up and turn off moments where the DC goes up to over 200mV for few seconds
b) why would go rather go for the one-shot approach?
I think we made a J-Fet version of post 200 too. I just can not find it at the moment.
One advantage of the totally balanced is 6dB more gain so this is less of an issue.
I like the basic simplicity of the one shot and the high gm J-Fets come handy here.
For totally balanced is has to be modified.
The 2SJ74 is the only P-channel low noise part on this planet at the moment.
Even for me it is getting harder and harder to obtain them.
A single high gm differential stage solves that problem.
One advantage of the totally balanced is 6dB more gain so this is less of an issue.
I like the basic simplicity of the one shot and the high gm J-Fets come handy here.
For totally balanced is has to be modified.
The 2SJ74 is the only P-channel low noise part on this planet at the moment.
Even for me it is getting harder and harder to obtain them.
A single high gm differential stage solves that problem.
interesting! Do you think there is a reason why they wouldn't make high gm low noise P-CH Fet? This just seems so strange! No one needs it?
When I build R6 of master piece I thought that the 6dB gain would have been enough to reach the 62dB-ish mark, but I was wrong.
With the Jfets I could just get to 56-ish balance usint 16 Jfets at Idss.
I agree with you, the one-shot looks simpler and has the potential of using only the high gm Jfet.
Consideration on the IF3602: granted it has very low noise and high gain, does it say how linear it is? That I guess is a big pro for the Toshiba's over other Jfets.
When I build R6 of master piece I thought that the 6dB gain would have been enough to reach the 62dB-ish mark, but I was wrong.
With the Jfets I could just get to 56-ish balance usint 16 Jfets at Idss.
I agree with you, the one-shot looks simpler and has the potential of using only the high gm Jfet.
Consideration on the IF3602: granted it has very low noise and high gain, does it say how linear it is? That I guess is a big pro for the Toshiba's over other Jfets.
Linear Systems promised a P-channel since several years. As far as they know they handed out samples on a Rocky Mountain show so they can make it. I did a major effort to get more information but did not succeed.
Why they do not bring that to market i have no idea. Also lateral mosfets are getting rare and both issues give me a lot of trouble because some of my commercial offerings need this parts.
I think Scott Wurzer knows more about the Interfets and as far as i can tell they work fine.
Why they do not bring that to market i have no idea. Also lateral mosfets are getting rare and both issues give me a lot of trouble because some of my commercial offerings need this parts.
I think Scott Wurzer knows more about the Interfets and as far as i can tell they work fine.
If you talk to Linear System they say they will release the J74 anytime now...which is obviously not true.
Reason why they wouldn't is unknown, but I confide they will.
Said that , the Toshiba's fet only have small gm.
My question is: why do manufacturer make a ton of different BJTs semiconductors and Vertical mosfets but they don't produce new Jfets dual, complementary and so on?
What is the main reason? It must be commercial, but I don't see why the electronic's world wouldn't need a complementary pair of very linear Jfets.
Honestly, BJTs in my opinion have little to offer compared to Jfets other than a big variety and higher gain.
If the Jfets could be made to these extent Jfet would be much more succesful.
What do you think?
Here is the Accuphase C27. The circuit is a bit traditional but it homes in on very good measurements.
http://www.accuphase.com/cat/c-27_e.pdf
http://www.accuphase.com/cat/c-27_e.pdf
I am not so disconcerned for the 1nV/Hz noise that is not the quitest in the planet however could be enough for vinyl reproduction, but mostly for the use of AD797 for the follwoing reasons:
1) they charge that high price and parts inside are just standard op-amp which design wise don't require that much of an effort if compared to an all discrete stage.
2) Sound of an opamp on the signal parth is not the best compared to the very best discrete stage and while I could expect that for entry levels I don't accept it when I pay that much.
Now, I know you make OP-AMP based high-end phono premaplifier and I am sure they are great sounding so there is no intention to attack your precious work, and I am an ignorant if compared to your experience, so I would really be very interested to know your take on this.
looks like a very nice discrete phono stage!!! A two stage desing and I am surprised they would choose BJTs on the FE with the cart.
Maybe the input offset is not so much a concern as I think it is.
However, isn't it too complex in your opinion?
Is it wrong to assume that an Opamp sounds worse than discrete? If it does sound worse, what would be the reasons for this. I know a few that were designed by very talented individuals in the business, who also love music. Really just wandering and seeking opinions from more experienced listeners and designers.
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