Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

The Lounge A place to talk about almost anything but politics and religion.

John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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
Closed Thread
 
Thread Tools Search this Thread
Old 9th March 2013, 12:29 PM   #36511
jacco vermeulen is offline jacco vermeulen  Netherlands
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
I'd name that a longcoming.
 
Old 9th March 2013, 12:35 PM   #36512
jan.didden is offline jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Westende Resort, BE coast
Quote:
Originally Posted by vacuphile View Post
I won't but I will. My shortcoming is that when I listen to the stereo system, I can no longer hear the music.
__________________
Cable: a potential source of trouble interconnecting two other potential sources of trouble - Erik Margan
Linear Audio pubs and articles . The SilentSwitcher now at diyaudio store SilentSwitcher. Keeping in touch with SY.
 
Old 9th March 2013, 12:44 PM   #36513
jacco vermeulen is offline jacco vermeulen  Netherlands
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Hurray, a case of no semantics ?
 
Old 9th March 2013, 01:54 PM   #36514
gpapag is offline gpapag  Greece
diyAudio Moderator
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by vacuphile View Post
I won't but I will. My shortcoming is that when I listen to the stereo system, I can no longer hear the music.
You have the right to remain silent.
Everything you say will be used against you.
Put the handcuffs on!

Smocking is not allowed there.

George
__________________
["Second Law is a bitch." - SY]
["I insist on respecting the means of the average person working in their garage/basement." -Scott Wurcer]
 
Old 9th March 2013, 03:40 PM   #36515
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Quote:
Originally Posted by simon7000 View Post
If you look at the bench photo you can see the test leads connected to the chassis. They are on the same side of the transformer as the sheet metal. What is being measured is the voltage across the length of the chassis.

The transformer is measured 3 ways. First unplugged, then with AC but no load and finally with a load.

The load is shown. It is two diodes going to a 50 ohm resistor filtered with a 2200 uF capacitor. In the ground leg is a .1 ohm resistor that has a transformer load on the secondary by 72 ohms.
This is a good beginning to learn that there really IS leakage and induced currents from transformers. The size of the transformers, the current draw/load and location from the audio circuitry, impedances involved, all impact the results in practice.
Next is to take the cheapest one and make it better than the others.... isolated from direct contact with chassis, shielding et al. Or, maybe just remote mount the supply for preamps and others.
Oh. And compare to UL leakage acceptance levels for safety. as well.

Thx-RNMarsh
 
Old 9th March 2013, 03:52 PM   #36516
Kindhornman is offline Kindhornman  United States
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
John Curl's Blowtorch preamplifier part II
John,
I think in an ideal world that all amplifiers would sound the same but I think we all realize that is far from the truth. What it is that makes us like one over the other is a better question than saying they should all be as transparent as a straight wire, which I have never heard.

I think that is really the reason that people are asking you why you chose one way of doing something over another. What makes you select certain components and how you arraigned them to get to your end result. If I thought all amplifiers did sound alike I would just go to the local Fry's and buy the cheapest sample that had the power output I wanted and move on. We still seem to be far from that ideal.
 
Old 9th March 2013, 04:23 PM   #36517
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Quote:
Originally Posted by RNMarsh View Post
This is a good beginning to learn that there really IS leakage and induced currents from transformers. The size of the transformers, the current draw/load and location from the audio circuitry, impedances involved, all impact the results in practice.
Next is to take the cheapest one and make it better than the others.... isolated from direct contact with chassis, shielding et al. Or, maybe just remote mount the supply for preamps and others.
Oh. And compare to UL leakage acceptance levels for safety. as well.

Thx-RNMarsh

JC tried to point out why his products have to cost what they do.... I would like to add on to that in another way.... UL safety and parts costs related to it.

In anything I do for others, i insist, or I dont work for them, that parts which touch ac line volatges must be a UL approved part.... every inch of it. I dont want to get sued, later. The cords, switches, fuses, fuse holders, capacitors, inductors, pcb trace size and materials and spacings -- everything pertaining to safe construction for sale to the public. Well, wouldnt you guess that each part that has VDE, UL et al stamped on them cost several times more than the same value without such testing and approved part? Several times as much. then it has to be constructed with similar care and standards applied. Then the whole package/finished product has to get approved ... more $$$ and many distroyed products later, you get to sell it to the public. I am not saying any brand is or isnt -- just that a good, proper and safe design cost a lot more.... and buyer beware! of what you get for your $. Specify it also be UL approved or dont use the transformer or cap etc.

Thx-RNMarsh

One of the test equip used for low power products -- test junky that i am -- attached;
\
Attached Images
File Type: jpg DSC00651.jpg (714.8 KB, 149 views)

Last edited by RNMarsh; 9th March 2013 at 04:27 PM.
 
Old 9th March 2013, 04:29 PM   #36518
Kindhornman is offline Kindhornman  United States
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
John Curl's Blowtorch preamplifier part II
Richard,
Is every part really marked with a UL approval stamp or is that a little beyond the requirement? Does an inductor even have a label many times or would a circuit board have to be checked before you could use it? Isn't it the product in its entirety that is tested by a licensed inspection lab to UL standards? And what about TUV or any European inspection requirements?
 
Old 9th March 2013, 04:56 PM   #36519
simon7000 is offline simon7000  United States
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by RNMarsh View Post
This is a good beginning to learn that there really IS leakage and induced currents from transformers. The size of the transformers, the current draw/load and location from the audio circuitry, impedances involved, all impact the results in practice.
Next is to take the cheapest one and make it better than the others.... isolated from direct contact with chassis, shielding et al. Or, maybe just remote mount the supply for preamps and others.
Oh. And compare to UL leakage acceptance levels for safety. as well.

Thx-RNMarsh
Thanks,

It was nagging at me I forgot one test. Leakage current and how swapping the primary leads affects it. Will try to post a bit after lunch and do a few more tests.
 
Old 9th March 2013, 05:02 PM   #36520
simon7000 is offline simon7000  United States
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Jan,

There was a reason why I mentioned the bit about testing the tester,

Let us assume I have a setup where two identical turntables with identical recordings, completely in sync, drive two different preamplifiers, that in turn drive identical amplifiers going to a single switch to a single loudspeaker in a well balanced room. The listener sit on axis and has an ABX switch. What does it prove if no listener can tell what x is? What if only one of the panel can tell? What if they all can tell?

Now if none of the listeners can tell, but the power amplifier is changed and the results change, what does that mean?

ES
 

Closed Thread


John Curl's Blowtorch preamplifier part IIHide 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

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 09:25 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki