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 17th April 2010, 03:23 PM   #1181
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Today i made more listening tests to loading resistors. The good news first : The 300 Ohm
TX resistor sounded much better then the 1Kohm. The thinness is gone replaced by a totally natural tonal balance. So again the message is that the value of the loading resistor is critical, maybe even more then the type provided you use a "good" one.
To describe the difference between the TX and the Dale RS65C ( sorry, i named it RS65E before but it is a C type in fact) is much harder. Both resistors sound better than all others i tried including NOS Tantal, Mil.Spec. Wirewounds, Caddock 132 and Dale RS55 unmagnetic. Tonal balance and resolution of micro detail is very similiar in both cases.
The TX sounding dead neutral and the Dale very slightly warmer. Concerning speed music sounds very fast with the TX and the Dale not far behind. I whould say that the Dale has the edje on older material like Hellen Merill in Tokyo and Katy Lied by Steely Dan. It is slighty more convincing on thoose tracks. Somehow it sounds more relaxed and magical. The focus is more on the music and less on the sound if you understand what i like to say. On modern Electropop and Funk like Electribe 101 and Nona Hedricks
the TX provides the more exciting ride. Listening to this kind of music on high volume left my breathless. No time for analysis.
The biggest differences apeared in terms of 3 dimensional soundstage presentation. The TX projected voices more forward and less high. The Dale had amasing height projection. On Hellen Merill i had the feeling that she was singing 5 meters away and 2 meters over my head. I can not say what i more accurate but i certainly enyoyed the Dale more in that regard. It gave a kind of hyperrealism that i only experience seldom in very high resolution Audio. It can not be compared to the life experience and seems to be an artifact of reproduced music, still it did not distract from enyoying the music, quite the oposite. I had that experience when i tested resistors for speakers and the good old Welvyn W22 was the most spectacular in that regard. I have shown that effect to several people that visited me and it never failed to impress. Why that is so i have no idea. Later the day i will download even more. I have a 138 Ohm TX and a 150 Ohm Dale RS65C for that. I also will listen to classical music first with the 300 Ohm resistors.
One remark : I whould rate both resistors to be in he same quality class so the Dale is a huge bargain when you have the space to mount it. Some TX could be thrown in for good effect if you like a more "Matter of Fact" sound. For comparison of size i made a photo of the tested resistors side by side.
Attached Images
File Type: jpg TX - Dale RS65C.jpg (76.9 KB, 358 views)
  Reply With Quote
Old 17th April 2010, 06:27 PM   #1182
bocka is offline bocka  Germany
diyAudio Member
 
Join Date: Jul 2003
Location: Hannover
Joachim,

in my previous post I mixed your first and second name, sorry for that typo. Which transistors did you use as FETs? Your final schmatic looks quite similar to the basic structure of post #62.
  Reply With Quote
Old 17th April 2010, 07:00 PM   #1183
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
When you scroll down the PDF you see transitor types and instuctions to trimm the circuit. After the trimm distortion is minimum so is DC offset. Theoretical that circuit can swing 2V with -100dB of distortion without global feedback. In praxis i measure around -90dB and that seems to be the boundary of what is doable without NFB. When you want better measured performance, see my INA developments.
Actually the basic circuit did not change much but i worked on the biasing and trimming. The circuit as is now has superb PSU rejection and can be direct coupled to the next stage.
Circuit in post 62 has a shunt feedback stucture and works well too. The stucture i recently posted has the 75usec part as transimpedance and the midrange-bass section active in the second stage. I think it sound good because i first reduce the trebe content in the 75usec transimpedance structure so high frequency junk from ticks and pops that come from scratches and dirt do not tax the second stage. Subjectively noise from the record is spacially seperated from the music so this circuit has a subjecively clean presentation of the music. Listening to old, worn records is posible with this circuit with minimal distraction. Tick and pops also sound very "short" in duration.
  Reply With Quote
Old 18th April 2010, 07:20 PM   #1184
gk7 is offline gk7
diyAudio Member
 
Join Date: Oct 2007
Location: Vienna, Austria
Is it the Dale RN65C ? Canīt find a RS65C anywere...
__________________
Regards,
Georg
  Reply With Quote
Old 18th April 2010, 07:30 PM   #1185
bocka is offline bocka  Germany
diyAudio Member
 
Join Date: Jul 2003
Location: Hannover
I've overlooked your marks at the end of the document. For T5/T8 I cannot find a BF446A JFET. Did you mean BF246A? In addition have you ever tried a lower beta transistor like the BC547A and BC557A for T6/T7? A higher beta results in a lower early voltage so y22 is also lower. As y22 is quite non-linear a high beta transistor has a higher distortion level when used as cascode transistor / common base circuit. At least in theory. I've never confirmed that in a real circuit as I ever used the lower beta types like the BC547A instead of a BC547C in this application.
  Reply With Quote
Old 18th April 2010, 07:52 PM   #1186
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Sorry, some mistakes came up. Yes, it is an RN65C. You can get it at Mousser.
The P/N is 71-RN65C1500F for the 150 Ohm for example.
yes, the Fet is a BF246A.
Yes, i tried lower beta in my Balanced INA desing. I used 2N4403, 2N4401. Anyway, i am very happy with the performance with that circuit. Distortion is around -90dB at cruising level. Other people sugested other transistors then the BC550C/ BC560C too but it is simply imposible to try everything. Do you have any sugestion ?
  Reply With Quote
Old 18th April 2010, 07:56 PM   #1187
lauret is offline lauret  Netherlands
diyAudio Member
 
lauret's Avatar
 
Join Date: Oct 2007
Location: Amsterdam
Quote:
Originally Posted by gk7 View Post
Is it the Dale RN65C ? Canīt find a RS65C anywere...
I believe I can read RN65C in the picture...

Edit: very late reply...
  Reply With Quote
Old 18th April 2010, 08:17 PM   #1188
bocka is offline bocka  Germany
diyAudio Member
 
Join Date: Jul 2003
Location: Hannover
Quote:
Originally Posted by Joachim Gerhard View Post
Other people sugested other transistors then the BC550C/ BC560C too but it is simply imposible to try everything. Do you have any sugestion ?
I think BC546 - BC550 are all the same chips nowadays. The only difference is the beta between them. BC546 or similar do not perform very well on higher currents. 10 - 20mA is the max. current before they degrade in parameters. ZTX450 and ZTX550 (Zetex / Diodes) are medium power transistors and have a very linear beta over quite a large current range. BD139/140 are also not bad for cascoding.
  Reply With Quote
Old 18th April 2010, 09:53 PM   #1189
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I think i have some Zetex. They have being recommended to me by another designer.
Of cause i also have BD139/140. I use them in my headphone amp.
  Reply With Quote
Old 18th April 2010, 10:05 PM   #1190
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
The Zetex i have is ZTX384C and ZTX214C. What do you think about those ?
  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 06:54 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2