Paradise Builders - Page 93 - 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 7th January 2013, 09:47 PM   #921
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Uhm, some development. HF oscillation under all conditions seems completely gone. Will try to find time and power both channels tomorrow but that's how it's looking atm. Infra low frequency breathing with some higher frequencies still modulated on output. In the absence of the HF noise it's now clear that the output not only "breathes" but there is some low frequency modulation too.


So, what happened? There has been some hf noise everywhere, even on the ground from day one. Not trusting the scope i didn't pay much attention until tonight. After running some tests it appears both polarities of the regulator contain some noise around 7-8MHz. Put together a quick 317/337 replacement and it appears all of this is now gone. It's getting late and i hope i am not wrong about this, but so far it looks that at least in my build it was the regulators oscillating.

The offset issue certainly remains.
  Reply With Quote
Old 7th January 2013, 09:53 PM   #922
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 analog_sa View Post
The context of 2k is obvious to all but the most casual reader. It's not even worth discussing.

The critical comment about the input offset has nothing to do with all the output offset and oscillation issues. It is more one of usability and safety.

Do you honestly think that for a user with several cartridges such a concept would really work? Every time you want to change a cartridge you remove the lid, plug in a dummy cart resistor and adjust input for zero. Nah, this cart doesn't sound this hot - repeat procedure and you're done. And you will never forget which was the last cartridge you set it for? Sooner or later something will get magnetized. I know there are demaggers, i think Cardas used to sell one, but in all honesty i don't know how well these devices work.

In any case, as i said, these are usability issues and have nothing at all to do with the twitchy offset and possible oscillation. If one owns a single cartridge and never lends equipment to friends, it's a moot point.
  Reply With Quote
Old 7th January 2013, 10:13 PM   #923
brianco is offline brianco  Ireland
diyAudio Member
 
brianco's Avatar
 
Join Date: Aug 2005
Location: Scottish Borders - Kelso; on the famous Tweed River!
The simple answer for you is to just drop the whole thing. You said a week or so that you had so done - yet you eturn simply to criticise. Why? Do you have some thing better?

SEveral people have built this wel ad are enthused - I suggest that you go back and check it out. To decry the whole thing when you admit you gave up some time ago will not get you any sympathy.

I apologise for being rough - I have spent the afternoon at the funeral of a friend and his wife who were killed in a road crash.
  Reply With Quote
Old 7th January 2013, 10:29 PM   #924
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Quote:
Originally Posted by brianco View Post
To decry the whole thing when you admit you gave up some time ago will not get you any sympathy.

You are seriously mistaken if you think i am looking for sympathy. And true, i had not touched it until today. I guess i'm a bit inconsistent, or just felt bored. Sorry if this offends your sensibilities. Luckily, there is a very simple solution - do not read my posts.
  Reply With Quote
Old 7th January 2013, 10:53 PM   #925
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Where is your humor gentlemen ?
It is just HiFi.
  Reply With Quote
Old 7th January 2013, 10:56 PM   #926
brianco is offline brianco  Ireland
diyAudio Member
 
brianco's Avatar
 
Join Date: Aug 2005
Location: Scottish Borders - Kelso; on the famous Tweed River!
I have to apologise for being so rough; I was today at a funeral for a good friend and his wife who were both killed in a dreadful road crash just before Christmas.

Perhaps you need to start at the beginning and simply work it through again having first re-read the major part of the thread. I am pretty sure that you may have made an error, or that a component or three may be inaccurately labeled. I have read some of your posts on other threads and know that you are skillful. Go back, check everything and then report here again. If several others have had no problems, then I suspect that there is something wrong in your build. Good luck!
  Reply With Quote
Old 7th January 2013, 11:35 PM   #927
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
Where is your humor gentlemen ?
It is just HiFi.

You know Joachim that some times it is lacking. Who would expect a massively expensive item such as this for the money it cost plus a chassis/case?

This, with a reworked Lenco, a decent carteride and arm, will outperform anything up to massive dollars/Euros/Pounds.

As you know I have been not too fit, but am now 100% again - for a deaf 70 year old! I have a great pair of your speakers: Thank you. Plus a lot of Be Yamamura cables, carbon bits etc. I am even now making two power amps [ the one you sent me, plus a Symsun TO-3 from Roender]. Also the buffer you sent with the FETs and - witin the next few weeks - will start on the Paradise - which is NOT ideal for my use, but a lot better than the 15 year old Ben Duncan MC stage I have been using with an Io.

I hope that I will be able to post some worthwhile comments soon.

In the meantime thank you, and your team, for all ou have done.

Have a great 2013 all of you!
  Reply With Quote
Old 8th January 2013, 05:01 AM   #928
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
Quote:
Originally Posted by Waly View Post
You must be joking. 5.2nV/rtHz noise (best case, can be up to 8nV/rtHz) plus the 150 ohm input resistor, that's about 6nV/rtHz (ignoring the servo contribution). Marginally good for MM.

If by 20dB you mean a transformer in front of this preamp, then that's not an apple to apple comparison with the Paradise. Try DC connecting those extra 20dB and see where your offset (and the LF fluctuations) are going. And I haven't even considered the temperature offset drift.

BTW, OPA177 has not less than 25uV offset. You do the math for 80dB DC gain. This would be a job for a chopper stabilized opamp (Vos<1uV) but then you definitely don't want such around a MC.
You did not get the point. The servo is connected to the second opamp in case of MC version. That means it remains connected same as in a MM version. The output offset I measure in a MM version is below 0.5mV at several samples built. BTW, your math is completely wrong. For DC servo, you do not simply multiply Vos times gain. It is clear to me that you do not understand how the DC servo works. If there is a self-promoter, it is you and not me.

MC version was not made with transformer, but LT1028 connected in front of the MM version.

This is completely OT here, but YOU were accusing me for giving not schematics, promotion etc. If you want to know more, send me an e-mail. I am NOT going to continue with OT in this thread.
__________________
Pavel Macura
http://web.telecom.cz/macura/audiopage.html

Last edited by PMA; 8th January 2013 at 05:07 AM.
  Reply With Quote
Old 8th January 2013, 05:20 AM   #929
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
For those interested in DC servos: DC servos compares output DC voltage with input DC voltage (usually ground) and sets voltage at the output of DC servo to drive the whole circuit to keep "zero" output voltage. In fact it is an integrator with time constant usually at something like 1s. The time constant of the whole circuit with servo also depends on resistor divider that is connected at the DC servo output.

DC servo can keep DC output voltage at the value close to Vos voltage of the servo opamp as long as voltage output of the DC servo opamp does not go to saturation. For the DC servo is an integrator, it may happen that the whole system's output DC would fluctuate, as it depends on behavior of the circuit that is inside the DC servo loop.

But, not that the output DC voltage of the whole system is DC servo input offset times DC gain inside the loop. This is NOT true.
__________________
Pavel Macura
http://web.telecom.cz/macura/audiopage.html
  Reply With Quote
Old 8th January 2013, 09:45 AM   #930
hesener is offline hesener  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Munich, Germany
Quote:
Originally Posted by analog_sa View Post
Sorry, wrong assumption based on Take5's successful build. In fact i only learnt about this peculiarity tonight. My arm is wired balanced and even though i used a single shared raw dc supply i never had the issue he describes. But it was surprisingly easy to duplicate. I should probably try a common ground point at the PS ground for the input ground return.
No problem. My arm is wired balanced too, and in my pre-regulator I use only one power transformer (it then goes through two different bridges and cap multipliers), one ground connection. My ground loop is pretty large though. I found it pretty important to have the GND's come together only at the input (star) ground, and the pre-regulator ground should be connected only at the board input power connector only, so the ground is routed to the input through the board.

It was quite natural for me to do that, maybe I should have spent more time while betabuilding, deliberately setting up ground loops and check if the circuit still behaves
  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
Paradise phono stage hesener Group Buys 1309 25th June 2014 03:23 PM
DIY Paradise - Any good to buy from? gingerpimp0069 Vendor's Bazaar 7 21st June 2007 02:07 PM
DIY Paradise Charlize Jolojl Swap Meet 7 7th December 2006 06:42 AM
Diy Paradise! alexmoose Tubes / Valves 3 24th July 2006 04:37 AM
Another way to paradise ? Bernhard Pass Labs 3 8th August 2003 10:19 PM


New To Site? Need Help?

All times are GMT. The time now is 08:33 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