Novel Topology MC pre-preamp - Page 2 - diyAudio
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 12th March 2010, 05:00 PM   #11
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
As has been pointed out, transformers are a much more expensive solution (although they do allow you to treat the signal as balanced, and therefore reject hum etc very nicely).

Valves are noisier than FETs because although it is possible to make the gm comparable, their grid current is noisier than a FET's gate current.

Despite the fact that I have some LSK170, I will probably use one of the superbeta bipolar transistors designed for low noise (Analog Devices SSM2210).

In the end, the implementation matters at least as much as the device...
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 12th March 2010, 06:00 PM   #12
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
I don't see the reason to think bjt i_b flowing in mc is a worry - the coil is setting in a air gap and the current can't have much effect on the near saturated PM biased pole pieces - the situation is completely unlike mm
  Reply With Quote
Old 12th March 2010, 06:25 PM   #13
wahab is offline wahab  Algeria
diyAudio Member
 
Join Date: Nov 2009
Location: algeria/france
I have designed and built a bjts input MC preamp, but i hesitate to use it.
Noise contribution is about 0.35nV/sqrt hz, but i have trouble
reducing the input DC voltage under 2uV.
In the waiting, i m using an AKAI preamp (that i did save from being
scrapped at the local scrapyard !!) that use 2SK150 dual fets at the input.
Attached Files
File Type: pdf 2SK150.pdf (100.1 KB, 50 views)

Last edited by wahab; 12th March 2010 at 06:25 PM. Reason: typo
  Reply With Quote
Old 12th March 2010, 07:28 PM   #14
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Wahab, could you post the circuit ?
2uV is not much. In a 5 Ohm cartridge it generates only 0.4uA or 8E.-13 W.
I do not think that is a problem.
I did a lot of transimpedance amps that generated much more and it did not matter how i abused the cartridge (Lyra Titan i). I always worked perfectly well afterwards.
  Reply With Quote
Old 12th March 2010, 11:11 PM   #15
diyAudio Member
 
Join Date: Apr 2007
Default Simulated Noise Floor for JFET MC Amp

Here is the simulated noise PDF for the MC amp with a 20 - 20KHz BPF applied. With a gain of approx 14, the equivalent noise referenced to the input stage is 0.27 nV/sqrt(hz). This was simulated with the input shorted
Attached Images
File Type: jpg noise_pdf.jpg (79.5 KB, 116 views)
__________________
JCM
  Reply With Quote
Old 12th March 2010, 11:30 PM   #16
diyAudio Member
 
Join Date: Apr 2007
Default Simulated Distortion for the MC Amp

Here is the simulated distortion for a 20 mVPP input into the MC amp. 20 mVPP is, of course, considerably in excess of what an MC cartridge can deliver. At lower input levels the distortion measurement is limited by the amp's noise floor. Remember also, that this is a zero GFB design.
Attached Images
File Type: jpg distortion.JPG (64.9 KB, 111 views)
__________________
JCM
  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
Pearl MC Pre-Preamp promitheus Pass Labs 230 5th July 2014 03:57 PM
Better MC Pre-Pre solution for low internal coil resistance- not only for Pearl phono tiefbassuebertr Pass Labs 17 27th June 2014 09:54 AM
Need suggestion for tube MC pre-pre inertial Analog Line Level 18 8th March 2009 08:28 PM
Schematic - B & K MC-101 Sonata (Pro-MC-10) Preamp dtm1962 Solid State 0 13th June 2006 07:46 PM
MC input topology: transformers or active stages? mrfeedback Analogue Source 29 20th September 2002 10:17 PM


New To Site? Need Help?

All times are GMT. The time now is 01:13 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