Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th September 2012, 04:48 PM   #41
diyAudio Member
 
Stefanoo's Avatar
 
Join Date: Apr 2006
Location: italia - ora USA -WI
Granted that ultimately precision and tweaking of the RIAA is done on the circuit with proper set up and equipment and not only driven by the simulation's tool.

What I find is that, usually, you can compensate a little bit with resistors and having custom values for caps and resistors is the optimal solution.

Once you determined on the circuit your ideal values that gives you the best RIAA recontruction you order the custom or you try to get the closest one and see if you can adjust with resistors.
__________________
Stefano
  Reply With Quote
Old 25th September 2012, 04:48 PM   #42
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Stefanoo View Post
On the other hand, also experimented with this, if from one side you get more benefit by paralleling more JFETs in terms of a bit darker background, from a sound standpoint, 4 paralled trannies yeald to a duller sound than a pair in front with a tad more degeneration and more gain distribution.
Now this is very revealing.... Thank you so much Stefanoo
__________________
RC
  Reply With Quote
Old 25th September 2012, 04:56 PM   #43
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I do two stage RIIA´s and one stage too. I general i prefer the simplest signal path as possible provided that distortion is under the audible limit.. Usually it put the 75usec in the first stage because that gives a better overload margin where it counts, suppressing bad effects from scratches and dirt.
  Reply With Quote
Old 25th September 2012, 05:00 PM   #44
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
By the way i do not have audible problems with electrolytics and coupling caps when they are used in such a way that they do not produce distortion. Servos have their own issues.
Best would be DC coupled without servo but that is hard to do with high gain circuits. I have done that in my line stage and in my power amps that have very good thermal stability because i use lateral mosfets. This kind of circuits can be hand trimmed without much drift.
  Reply With Quote
Old 25th September 2012, 05:21 PM   #45
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Joachim Gerhard View Post
I do two stage RIIA´s and one stage too. I general i prefer the simplest signal path as possible provided that distortion is under the audible limit.. Usually it put the 75usec in the first stage because that gives a better overload margin where it counts, suppressing bad effects from scratches and dirt.
I agree

The network that gives the 2122Hz corner (or 75uS) should be placed first because the signal coming off disc has its highest amplitudes at high frequencies, so we wish to avoid high frequency overload in our gain stages so we filter it before it becomes to large. The second reason is that we wish to defer filtering the low frequencies until we have amplified them up to a reasonably healthy level.
__________________
RC
  Reply With Quote
Old 25th September 2012, 05:28 PM   #46
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Now the big question...stefanoo removed the EL caps and got lower amplification but Joachim told me these are responsible for the bass response.. What am I missing ?
__________________
RC
  Reply With Quote
Old 25th September 2012, 07:18 PM   #47
diyAudio Member
 
Stefanoo's Avatar
 
Join Date: Apr 2006
Location: italia - ora USA -WI
Quote:
Originally Posted by Joachim Gerhard View Post
By the way i do not have audible problems with electrolytics and coupling caps when they are used in such a way that they do not produce distortion. Servos have their own issues.
Best would be DC coupled without servo but that is hard to do with high gain circuits. I have done that in my line stage and in my power amps that have very good thermal stability because i use lateral mosfets. This kind of circuits can be hand trimmed without much drift.
Joachim, thanks for your contribuite.
I haven't experimented with this topology yet in term of sound, and I am going to have a paradise's prototype ready for listening by tomorrow and then start swapping parts.
If from one side I agree with you, on the other hand I think that capacitor most of the time leave a sonical trace and most of the time is not measurable at all not in terms of frequency response nor distortion wise.
For example, different PSU filter cap.
You can explain certain things with ESR, capacitance value Ripple current, but, given pretty much the same specs, common practice suggests that they sound some time pretty different one from another.
This is my take so far and it can be wrong or impartially incorrect but it is what I know so far

Said that I can't imagine the boosting capacitor not leaving any significant trace on the sound and if it doesn't I will be extremely pleasantly surprised.
A straight test I am going to run is to have same values but different type, perhaps Panasonic FC and some cheapo nasty cap.
If there is no significant impact then I will change my approach on caps.
__________________
Stefano
  Reply With Quote
Old 25th September 2012, 07:21 PM   #48
diyAudio Member
 
Stefanoo's Avatar
 
Join Date: Apr 2006
Location: italia - ora USA -WI
The network that gives the 2122Hz corner (or 75uS) should be placed first because the signal coming off disc has its highest amplitudes at high frequencies, so we wish to avoid high frequency overload in our gain stages so we filter it before it becomes to large. The second reason is that we wish to defer filtering the low frequencies until we have amplified them up to a reasonably healthy level.[/QUOTE]

That is a good thought behind it! There is no end to learn; I would have done the other way around to filter better at the output high frequency noise.
However it just makes a ton of more sense to do it the way Joachim suggested.
__________________
Stefano
  Reply With Quote
Old 25th September 2012, 07:29 PM   #49
diyAudio Member
 
Stefanoo's Avatar
 
Join Date: Apr 2006
Location: italia - ora USA -WI
Quote:
Originally Posted by RCruz View Post
Now the big question...stefanoo removed the EL caps and got lower amplification but Joachim told me these are responsible for the bass response.. What am I missing ?
Maybe there was a sort of misunderstanding between you and Joachim.
In short, I am unable at this point to tell you exactly what the rule of these capacitors on the transfer function is unless I calculate it (which I might due when I get some spare time).
What I can tell you is that these capacitors are responsible for the bass response but at the same time, if you take them off your gain drops down, and you need a way to set your AC gain which you do it by inserting the resistor from the midpoint to GND.
You can see the effect of it if you model the circuit on the simulator, which is what I have been describing above.
__________________
Stefano
  Reply With Quote
Old 25th September 2012, 07:40 PM   #50
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Stefanoo View Post
The network that gives the 2122Hz corner (or 75uS) should be placed first because the signal coming off disc has its highest amplitudes at high frequencies, so we wish to avoid high frequency overload in our gain stages so we filter it before it becomes to large. The second reason is that we wish to defer filtering the low frequencies until we have amplified them up to a reasonably healthy level

That is a good thought behind it! There is no end to learn; I would have done the other way around to filter better at the output high frequency noise.
However it just makes a ton of more sense to do it the way Joachim suggested.
I have heard it argued that the stages should be the other way around because putting the HF filtering second will help reduce noise - this is possible but just ignores the reasoning above.
__________________
RC

Last edited by RCruz; 25th September 2012 at 07:45 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lyra Connoisseur 4-2L SE: What a masterpiece! Sigurd Ruschkow Solid State 56 18th April 2013 08:23 PM
A new masterpiece to add to the family... Guiness Tubes / Valves 20 2nd May 2003 08:37 PM


New To Site? Need Help?

All times are GMT. The time now is 03:29 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2