Why is my phono amp fatiguing? - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 9th October 2007, 03:02 AM   #21
diyAudio Member
 
Join Date: Oct 2007
Well Nick you are no neophyte! Yes but tank is much easer to type. Anyway I can see your problem and itís obvious Ė you need to ask your utility company to switch to 60hz AC and the Cornet will sound perfect. Oh I forgot you have upside down electricity down under so you will have to switch the wires around:^)

As for the ripple filtration stage for all my line level amplifies I employ CLCRC where C1 is calculated for ball park B+, L includes the tank circuit C2 filter, RC3 filter where R also server to fine tune B+. From C3 I branch to right and left channel with an additional RC filter/voltage divider/isolation circuit.

Good luck trouble shooting your phone and I hope I didnít fill your head with too much garbage. Let us know what finally resolved your treble fatigue.

Cheers

33dot33rpm
  Reply With Quote
Old 9th October 2007, 06:19 AM   #22
diyAudio Member
 
QSerraTico_Tico's Avatar
 
Join Date: Oct 2004
Default Re: resistor noise

Quote:
Originally posted by duderduderini
I found this document published by Vishay re resistor noise
http://www.vishay.com/doc?49435
It might be of interest to many
Cheers
Nick

Geeeeh, interesting history lesson.

The article does NOT deal with sound quality, only with noise.
Attached Images
File Type: jpg ccres.jpg (7.4 KB, 245 views)
  Reply With Quote
Old 9th October 2007, 12:32 PM   #23
diyAudio Member
 
Join Date: Mar 2004
Location: Albury NSW Australia
Default Here Here

Hi Again
Look I have to admit I am an unashamed dinosaur in some things..The thing is when I touch the power button of my amp(s) and I watch for that faint red glow and then hit the b+ after 20 seconds well its a feeling of acclomishment and amazement at tubes, their concept, their physics and their sound.... Likewise cc resistors arent so bad I dont think...If I wanted noiseless souless music Id go solid state ( i really hope they arent listening out there) CC resistors to some extent impart their sonic signature on the music and I, being carbon based, find it warm and appealing.
I concede that in some spots, bulk metal foil resistors are a boon. Mind you in Australia they cost 30 dollars each (for a .3 watt) so I will only maybe change the ones 33 dot suggested in my phono stage.
The same can be said of caps.. there these ones or those ones or russian pio caps made in the cold war or before which surprise surprise are the ones to get.
I respect everyones differing opinions and experiment where possible but it comes back to the fact that CC are cheap, mostly sound good and the ones I have been using seem to boast stability not once seen in older cc's because of newer or more precise manufacturing techniques.
So I agree with your comments for that article its about the measureable not the intangible. I was dissapointed to read in Morgan Jones book on valve ampos that he doesnt see the logic in SET power amps.. well I have 3 amps and the one I love the most is a 300B set so go figure.
The world is mad on measurements but thats not the whole picture now is it.
i will however report on using the bulk foil resistors in the places recommended and see what transpires.
I would like to thank all for the help, 33dot in particular.
Onwards and upwards
__________________
"Better to say nothing and keep them guessing than to speak and remove all doubt."
  Reply With Quote
Old 9th October 2007, 01:19 PM   #24
diyAudio Member
 
Join Date: Mar 2004
Location: Albury NSW Australia
Default What voltage ratings needed

Hi 33 dot
I have found the vendors you suggest but it seems the voltage ratings Jim suggests for c5 c6 and c8 are not available but either 200V or 400V. What are your caps V ratings?
Thanks
__________________
"Better to say nothing and keep them guessing than to speak and remove all doubt."
  Reply With Quote
Old 9th October 2007, 07:46 PM   #25
diyAudio Member
 
Join Date: Oct 2007
Hi Nick,

Donít go nuts with all the recommendations from this thread. I used all those exotic parts because they were in my parts box from years of packratting. The first priority is to determine if you have a circuit fault that is causing the treble fatigue and address that problem. If there is a fault and youíve fixed it then you can address tone and distortion at your leisure and have fun doing so.

Before you source all the components I used in my phono, dig into the parts box. Network with other audio hobbyist in your area and see if they have interesting caps or resistors you can borrow and try out in your circuit. In the end of the day it is only your opinion that counts. I like the tone of the Russian caps but you may prefer something else. The foil resistor is good for me (but I got it cheap @ a surplus store) but something else may work for you.

Regarding voltage rating of available caps for me as long as the rating is higher than specified itís ok. One of the limiting factors is higher voltage rating usually means larger physical cap. Some folks will argue that you should use the voltage specified only otherwise the amp wonít sound right of good. I believe for example C5: a 47nf 500V Teflon will sound superior to a 47nf 250V Mylar. If you can find a 47nf 250V Teflon great it will cost less. For C8 I can see your problem the most common rating for a K40Y9 is 400V and the spec is 630. There are 630V K40Y9 but not so common and the K72 is rated @ 500VÖ. what to do?

In many designs there are factors of safety. If you notice max B+ for the follower is 325V far below the 630V spec (I measure around 160V @ the output of the follower). There are two things to keep in mind depending on your PS design. In my phono itís unregulated CLCRC. First when B+ is turned on there is no significant load and B+ will spike then settle down as the tubes warm and the circuit applies a load to the PS. Second depending of the PS design you want to protect the circuit from a rise in B+ in the event of a fault in the PS.

In my case I use a small value cap off the rectifier to get the ball park B+ voltage. If this cap fails (short) Iím left with a choke input. In this case B+ will be lowered and I will have no over voltage problem with the rest of the circuit. You would need to calculate what will happen to your PS in the event of a capacitor or choke short (no idea what happens to a regulated PS). I can feel comfortable using a 400V K40Y9 parallel with a 500V K72 in my case.

Iím with you 300b SET is the way to go! You may get more bass slam with a tube PP or high current transistor but thatís what a powered sub woofer is all about.

Cheers

33dot33rpm
  Reply With Quote
Old 9th October 2007, 08:07 PM   #26
diyAudio Member
 
Join Date: Mar 2004
Location: Albury NSW Australia
Default Thanks for your encouragement

You are illuminating 33 dot. I appreciate your good and timely advice.
Will sort out the itch first before. I go gettin' exotic In the interim I will keep looking for the specified caps. I never would have thought the makers of the cossack motorcycle and other mechanical delights would end up making audiophile caps!!! Good heavens only knows how much the russian stuff would cost if mundorf or auricap produced them.
One other question...
I am probably going to use polypropylene caps in my psu for my monoblocs.. say 5 to 10uf for the first after the rectifier then a choke, then 47uf and maybe a crc for the 300b b+. I am debating wether to use regulated b+ for the 6 sn7/6ca7 driver stage..For this i would have to reduce the b+ down from 480V from the first stage of filtration via a voltage divider. I will probably run the 6sn 7 and 6ca7 at 250v.
I have an amp at home which runs 12at7 into a 6ca7 driving the 300b and it sounds magnificent to me so I thought i would just kind of use this circuit (monobloc parallel 300bs though).
The ppropylene caps i have in mind for power supply have a dc rating of between 700V to 1000V really low esr, high current surge ability blah blah... they are just kind of big. your thoughts on this?
Thanks again
Nick
__________________
"Better to say nothing and keep them guessing than to speak and remove all doubt."
  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
Which Phono Pre??? Freecrowder Tubes / Valves 1 5th February 2009 09:45 PM
DIY phono to replace roksan phono stage seroxatmad Analog Line Level 6 14th December 2008 05:46 PM
new phono stage or old preamp with phono? flohmann Analog Line Level 2 2nd October 2008 09:51 PM
Phono transformer VS Active phono pre ckwong99 Analogue Source 0 2nd November 2005 04:35 AM
Should I replace Scott 222C phono stage with Claret phono stage? Bing Yang Analogue Source 0 22nd August 2005 06:41 AM


New To Site? Need Help?

All times are GMT. The time now is 07:36 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