heater wiring - the Good the Bad and the Ugly - Page 9 - 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 13th February 2014, 08:47 PM   #81
mdamp is offline mdamp  Australia
diyAudio Member
 
Join Date: Jan 2013
Thanks for putting this together, it has helped me, I have switched from mains power to Standalone solar power 24vdc/220vac 50hz pure sine wave inverter and my valve amp now seems to be running prefect, as I now run 85% of my home on Standalone solar. I could run my heaters on the valve amp directly off battery power with a regulator reg the power at a constant 6.3v but it is easier now just to plug it into the pure sine wave inverter. You wrote on my post and it helped me I got confused on 1 thing but Am working that out {I think lol}
  Reply With Quote
Old 18th February 2014, 04:45 PM   #82
diyAudio Member
 
Join Date: Nov 2009
Hi Guido and valve 5425 and others thanks

Very interesting tread and answers.

I will go with a séparate filament transformer with center tap and try also some dc way.

I must say that I like old ways for tube amplifiers.

But an open mind is alwalys the best way.

Gilles from France, a rainy day in Normandy.
  Reply With Quote
Old 25th November 2014, 10:30 PM   #83
diyAudio Member
 
Join Date: Dec 2012
Location: Athens
I wondered if anyone has tried using Utp Cat 5e twisted pairs as heater wiring. They could come handy in case one gets bored (or afraid) twisting.

Could such a twist length be considered appropriate for the job?
  Reply With Quote
Old 25th November 2014, 11:20 PM   #84
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Rather small gauge and unless teflon insulated type the insulation seems to melt pretty easily. I just twist a pair of irradiated pvc wire of 20ga - 22ga or so with my electric drill if I need a longish run.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 26th November 2014, 03:48 PM   #85
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Cat5 pairs for heater wiring came up in another thread. The longest twist pitch on one of the pairs may be too long for AC heaters. Note that Cat5 gains its isolation not from tight twisting but from different twisting in each pair. It is solving a different problem: inter-pair crosstalk rather than interaction with nearby circuits.
  Reply With Quote
Old 29th November 2014, 04:07 AM   #86
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Here is something I did, it might help. The picture is not so good but you can see some of the copper the showing. They sell this kind of copy foil with conductive adhesive for electrical shielding. It is tough tape, almost like duct tape.

After doing the hearer wire I covered it over with copper tape. I did it all correctly, run in the corners and so on but then as an extra I cover it all in copper. This does 3 things (1) it looks cool and hides the wire and (2) it sticks the wires down and keeps them in place and maybe (3) it adds small amount of shielding.

Heater wires creat a magnetic field mostly and copper does not much for that but it might keep radio and what not out. And it looks good

https://www.dropbox.com/s/vhj9ykofaodw936/guts.jpg?dl=0

The amp BTW is a modernized clone of a Fender Champ. I used Fenders 50's vintage schematics but modern construction techniques and it is dead quiet with a very low noise floor. It uses a power supply choke and some slightly over sized filter caps and is wired with brightly colored coaxial shielded hookup wire with shields grounded at one end. The heaters are AC but running at 5.8 volts and the AC is biased up to about 1/10th of B+. This I find makes it run quiet.

Seeing as this thread is about heater wire I'll re-state the point of running at 5.8 volts. It is inside the allied spec of 6.3V +/- 10%. Running at the low end of the allowed range makes the tubes last nearly forever and put less current in the wires. I drop the volts with a large 25W resister in series with the transformer. Then I build a voltage diver so get about 20VDC and attach that to the heater loop also

Using coax wire and keeping the sheild on all the way to the tube sock pin keeps "hum" out of the signal

The Champ is a 6V6 power single ended amp. That is an ALNICO magnet speaker.

Last edited by ChrisA; 29th November 2014 at 04:20 AM.
  Reply With Quote
Old 29th November 2014, 07:15 PM   #87
RTF671 is offline RTF671  United States
diyAudio Member
 
Join Date: May 2008
Location: North Carolina, USA
How does the modern treatment affect the character of the end result?
  Reply With Quote
Old 29th November 2014, 07:47 PM   #88
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by RTF671 View Post
How does the modern treatment affect the character of the end result?
I worried about that a little. I tried not to change what I thought might matter. All the component values are the same, or really they are a cross between the first two versions of the Fender Champ. I think it is the circuit topology and component values and especially the choice of which output transformer to use that matters.

I changed these things:

1) Fender user the chassis for the return current from the heaters. They ran a 6.3 volt "hot" AC wire to each tune then connected the tube socket's other heater pin to the steel chassis. They use a short bare wire to jumper the socket pin to the chassis. I was actually surprised to see that solder would stick to a chromed steel chassis.

2) Fender also used the steel chassis for signal ground too. They soldered direct to the chassis.

3) Fender used cloth covered solid hookup wires in the signal path. I used shielded wire for all wires that connect to a tube's grid. I did not want those wires picking up "what ever".

4) Fender close of the 6th side of the chassis with a plywood panel. I though this was a fire hazard and also wanted more electrical noise shielding. I laminated an aluminum sheet to the inside of the plywood cover and adjusted for good mechanical fit.

5) added hum balance resister network to heaters, connected this to a roughly 20vdc bias made from a voltage divider off the B+. Used about 10f cap on this bias to ensure 0vac bias. This makes the current in both legs of the twisted pair equal and average about 20 or 30 volts above ground. I also placed a low value (maybe 0.5 ohm?) in series to reduce heater voltage.

6) later version of the champ eliminated the choke on the power supply, I let it in. I also used the larger filter caps in the seconder Cham version. I might have a stiffer power supply?

Power supply "stiffness" does effect the sound of a push-pull amplifier. This is because a PP amp's demand on power depends on how loud the sound is. The PP amp uses more current from the power transformer to make louder sounds. But a single end class A amp uses the most current when the input is shorted to ground. So,... A PP amp with a weak power supply compresses the music. It make the dynamic range smaller. This is normally a Good Thing. So MANY PP amps intentional are under powered. But there is no such effect with a Class A amp. So bottom line is I doubt my choke and slightly larger filter caps effect the sound. My ears say they don't. Well except to greatly reduce the hum and buzz.


I think NOT using the steel chassis for heater current return and going with a STAR ground for the signal ground very much reduces the noise floor as well.

This amp sounds like a Champ but with reduced noise floor.

The noise is almost 100% from the guitar. But I've added 100% full copper shielding to all the routed cavities. The copper foil is soldered to a drain wire that connect at the 1/4" output jack. This allows me to play near a computer and under many CFL lights. It s not 100% effective, more like 80%
  Reply With Quote
Old 1st December 2014, 04:22 PM   #89
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
This hum from guitar circuit can be reduced too
The problem is that all metal plates carrying the elements, pots, switches and jacks in some,
have thin layer of nickel or other shining stuf.
with the years this layer is not too tight to the metal plate and there is some oxidation in the
space between. As the grounds are usually soldered at the pots chassis, via mechanical contacts they are summed "together". With this layer of nickel...
.
I desoldered all grounds from pots, make one solid ground point and soldered in that point all, added a good health point from the plate.
At my telecaster bigsby, and other telecaster standard hum was gone, and everything was much clear then before
__________________
###
  Reply With Quote
Old 2nd December 2014, 05:10 PM   #90
macm75 is offline macm75  United States
diyAudio Member
 
Join Date: Dec 2004
Location: PA
Default wire gauge

Hi,
Concerning wire gauge per heater current requirements (hope this thread is appropriate)...
I referenced the American Wire Gauge tables but wondering if more conservate measures should be made. For instance, my application is for a 3A filament. I'm in breadboard mode and just used the stranded 20 awg wire I had at my disposal. Single 20 awg has a max rating of 11A but questioning if I should be using more like 16 awg.
Any rule of thumb for gauge per current?
  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
The Good. The Bad and the Ugly Car Amps boxcustom Car Audio 115 17th August 2011 02:34 AM
OPT -the good, the bad or the ugly ?? AuroraB Tubes / Valves 1 10th February 2007 12:07 AM
The good, the bad, and the ugly OTL amplifiers Original Burnedfingers Tubes / Valves 46 9th November 2006 07:27 AM
Preamp Numbers; good, bad, ugly? chris ma Solid State 4 3rd September 2002 05:49 PM


New To Site? Need Help?

All times are GMT. The time now is 01:47 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