Jack wrote:For 6.3V DC, the simplest approach is to use a 10A bridge and a 1000-10000uF cap. The voltage gain by rectification is compensated by the voltage loss in the diodes and the filtercap. On the marshall JCM900 SLX, that's what they do and it gives a 6.27 V IIRC. If you worry about regulation, get a furman thingny. From my experience, the heater can work equally well between ~ 5.5V and 7.2V without perceivable tone change. The change on the B+ would be much more perceivable IF the bias is fixed. But since the bias voltage will drift accordingly, just like a power scaled amp, you end up with nothing to worry about at all.
IMO, having a voltage regulator in a guitar tube amp is like fuelling your land mower with super.
We used to call that brute force regulation. It will depend much on the number of tube filaments etc and is designed by EXPERIMENTATION. Hehe
Well The recipe for 3 12ax7 is a bridge with a 10KuF
From memory I think it's broadly 10,000uF per amp drawn for 10% regulation. That would be about right for 3 12AX7s totalling 0.9A in the JCM900, but it still leaves an appreciable amount of ripple.
Jack wrote:
IMO, having a voltage regulator in a guitar tube amp is like fuelling your land mower with super.
We used to call that brute force regulation. It will depend much on the number of tube filaments etc and is designed by EXPERIMENTATION. Hehe
I thought everything in electronics was designed using an "iterative method" until the prototype works. Guess that's why DYI design gets so frustrating
... and what's wrong with super in the lawn mower? - oh yeah... RoHS...
skyboltone wrote:Back to the $7 Xicon 3amp filament transformer.
Not to divert attention from the original topic, but those $7 Xicon 3 amp filament transformers are just what I've been searhing for. When you buy 10 they're only $5.82. Such a deal. Thanks.
So build a voltage doubler for the five volt supply, use a 7806 and run the low level tubes on regulated DC. Problem fixed. I've done this with Hammonds, Fenders, Traynors and others. A 7806 in a TO-220 case will support a pair of 12AX7's at 6.3 volts, the chassis provides a free heatsink, and your done.
Spare us the drama...................................
mooreamps wrote:
skyboltone wrote:<bump>
I'm serious about these questions. Anybody know?
"There are things like flux density, core saturation and other stuff to consider besides a winding opening up;
(1) Is a 4 amp 6.3V winding only good for 4 amps if the 5 volt winding isn't used at all?
(2) Can a 5V 2amp winding even deliver enough additional power to damage itself, or does the voltage just drop off to nothing with additional load? Sometimes you can short a winding and nothing happens"
The "teacher" has been busy working on the spacecraft.....
1. The 4 amp 6.3 v winding is good for 4 amps, regardless if you use the 5 volt tap or not.
2. Now, if you use the double-bridge, you can use the 6.3 v tap at full rated current, and the 5 v tap at full rated current.
3. The transformer I've selected is rated for 6 amps on the 6.3v tap and 3 amps on the 5 v tap.
4. Other methods do not midigate voltage sag, and yes it drops lower than 5.5 volts.
This works for me
Get with technology people !
No transformer needed, Universal input 85~264 Vac run the power tubes in series (in pairs) if you want DC heater supply to them.
5.4A on tap
Works like a charm, very easy to hook up http://www.cui.com/pdffiles/VOF-65%20Series.pdf
You want the VOF-65-12 $26 from Digikey and you are done with all the heaters, you can also use it for 12V switching, it has a trimmer to tweak it to 12.6V
Done deal no mess no fuss
Personally I leave the power tubes AC cause if the wall drops low enough to cause a heater problem, the B+ will start to make the amp sound crappy.
drz400 wrote:This works for me
Get with technology people !
No transformer needed, Universal input 85~264 Vac run the power tubes in series (in pairs) if you want DC heater supply to them.
5.4A on tap
Works like a charm, very easy to hook up http://www.cui.com/pdffiles/VOF-65%20Series.pdf
You want the VOF-65-12 $26 from Digikey and you are done with all the heaters, you can also use it for 12V switching, it has a trimmer to tweak it to 12.6V
Done deal no mess no fuss
Personally I leave the power tubes AC cause if the wall drops low enough to cause a heater problem, the B+ will start to make the amp sound crappy.
drz400 wrote:This works for me
Get with technology people !
No transformer needed, Universal input 85~264 Vac run the power tubes in series (in pairs) if you want DC heater supply to them.
5.4A on tap
Works like a charm, very easy to hook up http://www.cui.com/pdffiles/VOF-65%20Series.pdf
You want the VOF-65-12 $26 from Digikey and you are done with all the heaters, you can also use it for 12V switching, it has a trimmer to tweak it to 12.6V
Done deal no mess no fuss
Personally I leave the power tubes AC cause if the wall drops low enough to cause a heater problem, the B+ will start to make the amp sound crappy.
Bogner does this in the Shiva.
yes I know I own a Shiva, but he doesnt mount it correctly, it should be on the side.
Is this the famous Mark Cameron?
The only variable internationally is making sure the transformer can handle 50 hz power. What happens at the secondary doesn't change in Europe from the US. If the input voltage is proper (240 or 120 V) the output voltage should be the same.
drz400 wrote:This works for me
Get with technology people !
No transformer needed, Universal input 85~264 Vac run the power tubes in series (in pairs) if you want DC heater supply to them.
5.4A on tap
Works like a charm, very easy to hook up http://www.cui.com/pdffiles/VOF-65%20Series.pdf
You want the VOF-65-12 $26 from Digikey and you are done with all the heaters, you can also use it for 12V switching, it has a trimmer to tweak it to 12.6V
Done deal no mess no fuss
Personally I leave the power tubes AC cause if the wall drops low enough to cause a heater problem, the B+ will start to make the amp sound crappy.
Bogner does this in the Shiva.
yes I know I own a Shiva, but he doesnt mount it correctly, it should be on the side.
Is this the famous Mark Cameron?
?Famous?? I dont know about that? I left just when he started to do that. Did you find a problem? I know what you are saying about the mounting but it seemed to work fine.
Cameron wrote:
?Famous?? I dont know about that? I left just when he started to do that. Did you find a problem? I know what you are saying about the mounting but it seemed to work fine.
yes I just notice the efficiency specs are a lot better on the side in dealing with heat.
Is Jose mod is quite a bit hotter than the original version? The real Jose I had was not very gainy.
Not to derail the thread but when is that new amp comming out?
You going to have dealers?
Last edited by drz400 on Tue Oct 09, 2007 11:41 pm, edited 1 time in total.
