Speaking of polarity, jvc may want to check the V2 cathode cap. Some one with better eyes may want to have a look at the pic on page 19. It looks like it may be in backwards. Apologies if this is a false alarm.
Thanks Telentubes. The only damage seems to be that poor little caps life
telentubes wrote:And how bout the "headphone trick" to see if any hum is coming from the OTs proximity to the PT?
I did the headphone thing with my last Champ build. I found it impossible to eliminate the last 5% of hum until the two trannies were 10-12 inches apart, regardless of orientation.
surfsup wrote:Xtian, RJ, has the schematic for your eagle premium ever been posted?
Could an updated schematic be reposted? I saw the supre svhemo, cant find this one in all the pages. Or maybe edit the first OP and put em all there.
Surfsup - The schematic is identical between the Eagle 100 and the Eagle Premium, except for the transformer designations. Rather than try to keep up version control on two separate schematics, I'm going to leave that as is.
I'm going to think about your idea for putting them all on page 1. That idea might have some merit.
The Eagle Supre schematic has been posted but is even more of a work in progress because none of those amps have been built yet. One unique difference in this schematic is the addition of a tone stack.
I am enjoying the chance to gather info on this power supply filtering discussion. I would say that one thing we ought to write in the lesson book is that you can build your own Single Ended amp for around a $100, but you should expect some "normal" amount of hum for that amp circuit. It seems that adding nicer transformers and "high grade" filter caps hasn't really made a big difference so bigger caps and maybe a choke will help.
I did use a NOS 16uF Sprague in my build and I don't find the hum to be all that noticeable, do you suppose they do something better than the F&T caps?
In Gerald Webers first book he warns that changing the filter cap values will change the character of the Champ substantially and we've heard a few reports of that. I haven't done it myself but it sounds like we have the baseline established to learn that.
Depending on how this all turns out I might add more filtering to the Eagle Supre. That amp will get loud enough for any hum to really stand out.
According to Merlin, to get the resevoir capacitance value, doing the math using:
Cr = (t*I)/Vr
Vr = 10% of Voltage
V = 300VDC
t=time cycle to charge = 1/twice the mains (60Hz)
I=current average = 60mA
I get a value of a resevoir capacitor of 16.67uF and if memory serves xtian and all these builds used 16uF. For single ended, he states you might want to shoot for 5% ripple voltage. In the book there's a graph showing the differences between a large cap and a two-cap parallel application that is interesting. Not sure if I should mention more since it is in the book and not available on the freeweb site.
You should be able to solder it in parallel with the first rail cap to the same turret if there's room. Maybe Mark or RJ could confirm that approach as I'm a noob.
Something like this, where the black ground and red drawn in MSpaint leads go to the turret and it sits in the little valley between the other two caps. Not sure if there's heat issues or what, but the TW amps all stack caps. I think it would work, but get confirmation on that!
surfsup wrote:Something like this, where the black ground and red drawn in MSpaint leads go to the turret and it sits in the little valley between the other two caps. Not sure if there's heat issues or what, but the TW amps all stack caps. I think it would work, but get confirmation on that!
I'd do it for the quick and dirty test and see what happens. As mentioned in the Trainwreck PS you parallel two 40uF caps to make 80uF then stack and glue a few on top and life is good. If it really starts to make a big difference and doesn't create a downside tonally speaking, there is plenty of room for a bigger cap in that spot. This lets you solve a problem and preserve the simplicity of things.
Here is the only tone control that I am using on my Eagle Basic.
By the way, is there any progress on the hum issues? I have been playing mine a lot and it seems to sound better all the time. I can turn this amp on and sitting 5 feet away I have to strain to hear it hum as the tubes warm up and it starts amplifying. If I dime it the hiss totally swamps any hum I could hear but nothing that seems outa line for amount of volume I am getting out of it. I occasionally plug in my Strat and in the single coil modes I get the expected hum. This provides me a reality check for recognizing excess hum. Anyone else having similar experiences?
I did finally have one disappointment with it. I hooked up the pedal board through it yesterday and I wasn't overwhelmed with delight over the sound, especially the overdrive pedal (Bad Monkey) sound. I do need to try it more than once and somewhere else besides my office.
I haven't taken it out for a test run anywhere mostly because I haven't put it in a cabinet yet. Still deciding whether I need another head cab or a combo for this effort.
I got a shipping notice from Edcor today indicating that the Supre trannies are on their way. I'll go push on the machine shop tomorrow and see where we are with the chassis prep work. There is lots of activity right now in the Single Ended amp DIY world. Should be fun to take these efforts up another notch.
rj
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Hello, all. I have been lurking around on this forum for a few months, participating on others longer. Great, great knowledge here, hence my silence. Recycled thrift store and garage sale iron. Maybe it has been mentioned in the last 25 pages but I just dont have that sort of time tonight. Great thread and a great forum. Rock on.
Will someone please direct me to the page(s) with the most up to date schematics and layouts for the basic model and the one I saw with tone controls (treble and bass)? Thanks...and I second the suggestion to put them all on the first page.
It would be useful, when adding to this thread regarding troubleshooting, to include info regarding which model amp you are building and what guitar(s) you are using.
