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Another Maggy Thread

What was the final B+ Volts?


BTW, I'm really looking forward to seeing what you think of the bass with Keg's circuit. If there's anything that I feel could be improved on these little Maggies, it's the bass. It can (on certain cuts), be a hair on the flabby side. Not bad (and very seldom), just maybe a little.:scratch2: I have a feeling it may be the limitations of the OPTs, but you never know.
 
jaymanaa said:
What was the final B+ Volts?


BTW, I'm really looking forward to seeing what you think of the bass with Keg's circuit. If there's anything that I feel could be improved on these little Maggies, it's the bass. It can (on certain cuts), be a hair on the flabby side. Not bad (and very seldom), just maybe a little.:scratch2: I have a feeling it may be the limitations of the OPTs, but you never know.
Click to expand...

278v to the front end and 300v to opt's and 6gk6. I have decided to try the original opt's. I have some hammond 1620's i was considering. May try to clip those in when i get it built to compare the two. Gonna take awhile to get built as with spring comes alot of honey-do's. Will definately post results and maybe so construction pics.
 
That supply will work, but if it were me I'd do it just a bit different, as I wasn't
completely happy with the way the sim was running and I like the slow warmup
5AR4 rectifier over the 5U4 plus at this current any 5AR4 should have no issues.
(I'd use a nice Solen poly for the first cap) (you can try a 5V4G here to)
(I dropped the output tube current down a tad more in line I think as well) :)

You could sub a Solen say 33uf poly for the front end cap to for a nice upgrade.
 

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Thanks Kegger, I'll probably try the 5v4g as I have some of those. Gotta check out my stash to see if I can work the p/s closer to what you suggest. I may place another order also. As always, thanks for the advice. Stan
 
8802 problem

Tonight, I undertook some repairs and upgrades on my 8802. First, I replaced one damaged wire. Second, I pulled the original coupling caps and upgraded them to .01 and .1uF orange drops. Third, I removed a gigantic old 20uF paper cap that was installed in place of the 20uF cap in the can (which is a replacement itself - both the can and the big paper thing are GEs) and connected the wiring to the 20uF leg in the can.

Everything sounds great, but the bass seems a bit "thin" now. It might just be the little speakers I have plugged in right now, but is there anything else I should think about changing to balance out the upgraded coupling caps? I've seen some references to replacing the 30uF cap in the can (C2D on the schematic) with a larger value, but I'm not really sure what size to use.
 
Power Rail upgrade time!

What I normally see is keep the first capacitor at stock or at least do not raise it so far that it endangers your rectifier tube.

(Some people do like to push it a bit if they are running Old stock tubes)

But the second capacitor is fair game to upgrade to 80 - 150uf pretty easy, some might go higher to 200-220.

I have enjoyed tighter bass with 80 and 150 upgrades, just depending on what I had on hand.

I suspect you can upgrade the third cap also, I am not certain of the restrictions or guidelines on that. I know in guitar amps like old fenders they just boost them all up a bit, maybe double the original values. (except that first one)

I don't think it will ever be a bass monster. But I think the sound should be very enjoyable and if it is not them more tweaking will certainly not hurt!

Hopefully a few more opinions will pop up shortly.
 
Maggie

Ok, I finally finished building a modified Maggie 9300 using 6gk6's as suggested by Jay, and Kegger's update of Jay's schematic posted earlier.(except for grid stoppers and screen resistors) I also shamelessly borrowed from Redboy's Maggie layout. It sounds Great!! It uses original 930x iron. ( I put some different enclosures around the opt's) Only problem is some excessive hum that I can't track down. I created center-taps for the heaters( i used both 6.3 windings ) but that did not seem to help. If I can get rid of the hum, I will be extremely pleased with this amp. Oh yeah, I used the power supply that I posted.
Stan
 

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OK, so I have tried moving wires, changed wires going to inputs to shielded wire, created center-taps for heaters, paralleled p/s caps with another cap (to seeif maybe caps were bad) and I still have quite abit of hum. Too bad too, cause this baby really sounds good. Haven't tried the heaters on battery supply yet, I think I have filament trans. that i may try. I seem to be getting the same amount of hum on both channels. Any ideas?
Stan
 
Other things to check are ground solder joints, it looks like you have a star ground of sorts near you power transformer, i have had some cold joints when trying to solder too many wires together. You have some unused lugs near the ground you can divide the wires and make a ground bus.
also try a portable cd or mp3 as an input to make sure you are not getting a loop from the source. Lastly extend the RC filter out a couple more stages.
 
Ok, I will try a bus. I do have a star ground there using 2 lugs, and you are right, probably too much for these 2 spaces. I tried making sure I soldered them good but I do have a big glob of solder. It does seem to reduce the hum alittle when I touch the ground spot. I have yet to try the filament transformer either to ensure it is not the heater supply. I used both 6.3 windings on the tran., one for each channel. I will give these things a try. Thanks, Stan
 
Sorry we've been at the fest and it's been quite a full an tiring experience.

--------------------

Stan if I had a "guess" where your humm might be coming from I would say
try turning the choke and or outputs in different directions then what there
at now as you may well have stray magnetic/ac fields interfering with signal.

If you could just loosen them and turn while listening may find it's happening.

On an amplifier that is not running directly heated triodes you should not be
needing anything but AC on the heaters, that battery test is not a bad idea
to rule out some wiring issues but DC on the heaters is not needed here.
 
Thanks Kegger, I will try that as soon as I can. I re-did ground lines last night but there was no change in the hum. While it can't be heard during the music, it is very audible with the volume low or in between songs. Gotta say that circuit sounds really good otherwise. Hope the Fest went well....maybe one year I can make it. Stan
 
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Still chasing the hummmmm..... Moving the choke helped alittle but got no change at all when turning the opt's. I think i'll try different output trannies to see if that makes a difference and if not i may rework the p/s. Having trouble placing the choke in another place as i was trying to limit number of screws thru the chassis.
stan
 
Do you have a scope and a cheater plug to lift the ground? Just curious to what is riding on your B+ and the signal.
 
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