Mpp - Page 874 - 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 31st March 2013, 12:55 AM   #8731
brianco is offline brianco  Ireland
diyAudio Member
 
brianco's Avatar
 
Join Date: Aug 2005
Location: Scottish Borders - Kelso; on the famous Tweed River!
Quote:
Originally Posted by Joachim Gerhard View Post
....

The major flaw of the Wheaton is a beam resonance at ca.300Hz.
I think that gives it this robust tone..............
Thank you for that Joachim as it may explain a problem I had a few years ago.

I used a Tri-PLanar MKIV (the first fat tube one) with SPU and Io cartridges. The bearings would unlock after about an hour. I knew that those cartridges were producing a lot of mechanical energy and maybe the beam resonance hastened the un-screwing of the bearings? I went back to a Zeta and a heavy unipivot. But, when all was well the Wheaton was very good.
  Reply With Quote
Old 31st March 2013, 12:57 AM   #8732
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
When i measure the frequency response of a cartridge in my Wheaton there is a small "blimp" there. There is another way to measure the beam resonance. That is with a lead weight on a string. I published both measurements here before.
It is not a big deal.
  Reply With Quote
Old 31st March 2013, 01:11 AM   #8733
AVWERK is offline AVWERK  United States
diyAudio Member
 
Join Date: Jan 2004
Location: So Calif.
You can also place another arm and cartridge on top of the headshell and adjust accordingly the tracking weight, and note the output of the combo placed on top.
Kind of a cheap poor mans strain gauge
Been awhile since I have done it though
  Reply With Quote
Old 31st March 2013, 02:43 AM   #8734
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Here are some measurements on beam resonances :
FX-R
Obviously a triangle is the most stable shape.
  Reply With Quote
Old 2nd April 2013, 07:18 PM   #8735
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I got a Quantum Asylum Audio Analyzer.
I made a loop back measurement and got the 3rd harmonic at ca.-105dB. That is around 10dB worse then Audio Precission teritory but 10dB better then i get with my E-MU 0202USB so i think this is usefull.
Just for fun i measured the B1 buffer i build quite a long time ago.
At ca 1.3V RMS ( around 4V P-P ) i get around -95dB distortion. I think for something so simple this is very good. I also show distortion at lower volume and the volume where the third disappeares in the noise. The first picture is a loop back measurement of the analyzer.
The last picture is intermodulation with a 10kHz -10dB sine mixed in.
Attached Images
File Type: jpg QA400 loop back.JPG (227.0 KB, 178 views)
File Type: jpg B1 buffer 1,3V RMS.JPG (232.0 KB, 175 views)
File Type: jpg B1 buffer -10dB.JPG (225.2 KB, 167 views)
File Type: jpg B1 buffer 3rd disappear level.JPG (229.3 KB, 164 views)
File Type: jpg B1 buffer intermod 1k 10k.JPG (235.2 KB, 160 views)
  Reply With Quote
Old 2nd April 2013, 08:27 PM   #8736
diyAudio Member
 
Join Date: Aug 2010
Nice tool

Would you mind to measure also the "JG" buffer used in the DAC filter buffer? Just for fun
  Reply With Quote
Old 2nd April 2013, 10:06 PM   #8737
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
If i had one in isolation, yes.
I have it on the XEN ESS board and on the Paradise.
We simulated it though and it has ( much ) lower distortion provided it is not driven out of class A or voltage overdriven.
I can make an even better buffer especially if more voltage and current is needed.
The attractive thing with the BF862 based version is the extreme compactness.
  Reply With Quote
Old 2nd April 2013, 10:10 PM   #8738
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Concerning measurements, an AD797 buffer with common mode compensation would have no measurable distortion, even on an AP. Does it sound better ?
I think the success, subjectively, of my buffer-filter is the extreme simplicity combined with the good performance.
I do not think that static distortion measurements tell us all about the sound.
I wish it would be that easy.
  Reply With Quote
Old 3rd April 2013, 02:12 AM   #8739
MiiB is offline MiiB  Denmark
diyAudio Member
 
Join Date: May 2005
Location: Denmark
No you solden"t, if i was that easy, Them there would be no room for you, or for me..
  Reply With Quote
Old 3rd April 2013, 08:22 AM   #8740
diyAudio Member
 
Join Date: Aug 2010
I am fully aware of the fact that good numbers do not necessarily correlate with good sound. I just wanted to get an idea of the measured performance of the buffer.

I was too lazy to simulate it on my own. If I would have done it, I would have seen that the buffers distortion figures will probably not be measurable with the given equipment Just found the thread from calvin about preamp buffers with simulation results.

The subjectively perceived quality I know very well
  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



New To Site? Need Help?

All times are GMT. The time now is 04:53 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