Yet another completed project ...Velleman Tube amp

ohbythebay

ohbythebay

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So after practicing on my M65 solid state amp and honing my skills, I was ready - Attack the Velleman...have wanted to do it for a while but it is NOT an amp you mess with for fear of issues that will drive one mad.

I had all my caps, my DMM, my capacitor discharger (self made), soldering station..etc. I took my time, one by one, double checking rating, + and - in the right direction. Changed all the electrolytic caps except the big blue Philips caps.

So how did it turn out ? Great ..but read THE SCARE.

The Scare
So after all was done, I powered it up, checked the heater voltages, etc. All tubes in, fired up...oh crap..I hear a few pops through the speakers. So I shut her down. Now what ?

Fired it up again, a few more pops and ticks...then it stopped...occasional pop for the first minute...then no more...hmmm..capacitors forming ?

Now I start the music...oh my god ..sounds like crap. Re-bias and it was close anyway...let it play...check 10 minutes later...perfect.

So let it play and 30 minutes later, rechecked and set the bias.

Listening ? OMG...Never sounded so good. No more transformer hum (okay you know its on but like night and day), no hum or bzz through the speakers and the sound is awesome....will let it play for at least 5 or 6 hours each day to break in the caps.

HOW SWEET DOES IT SOUND
I have been playing digital and vinyl - everything from Sade to Hotel California, Dire Straits, Racal Flatts, Elton John...all of it..amazing. I loved it before...I love it more now...lol


THIS THREAD IS WORTHLESS WITHOUT PICTURES..as someone would say

Top side
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Bottom side
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Recap done...Nichicons are blue now ...
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Breaking in and playing...covers off...just in case...lol
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damn Rob!!!! nice job. you keep busy thats for sure.
great work !!!! the pops would have scared me to the point of not trying it again.lol.
glad it all worked out in the end.
 
Thanks Steve..yes scary ....I have since let it cool, restarted, etc. several times. No issues....Might have been the caps forming (power going through the signal) or a solder joint flowing into place (lol)

All I know is she sounds sweeter than ever...I am so freakin happy I didn;t blow it up !!! LOL
 
Rob - good work! Tubes rule! :). Love the pics.


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Rob, that's just amazing to me. I wouldn't have a clue how to do the things you tackle, Wow !!
 
Guys...its not as hard as it looks.

If you have the assembly guide or service manual, it gives you all the specs to order the caps. Then they have a diagram that numbers where they go. Sort of like paint by numbers but with capacitors...LOL. You just have to know how to de-solder and solder.

Several rules
Always check the + and - side of capacitors - put them in backwards, they tend to explode at start-up
Check and double check specifications - make sure you are putting the right value in the right place
Always wear pants when soldering - need I say more ? :exciting:
 
ohbythebay said:
Always wear pants when soldering - need I say more ? :exciting:
Click to expand...
LMAO!!!!!!!!!!
like working in a kitchen, when working with any kind of pepper,hot, crushed red,ground white or black pepper. always wash your hands before you pee as well as after. or youll be sorry. :)
 
Yup..in fact, I do work in the kitchen !!! We have a granite island that is HUGE and makes a great 8 ft long workspace. I put down a board and blanket (just to be safe) that keeps the equipment from getting banged. Outlets are right there for the soldering iron, lots of light...I DO wear rubber shoes, tile floor and have a capacitor discharger I made myself...No suprises please


Home made capacitor drainer...
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Petro85 said:
LMAO!!!!!!!!!!
like working in a kitchen, when working with any kind of pepper,hot, crushed red,ground white or black pepper. always wash your hands before you pee as well as after. or youll be sorry. :)
Click to expand...

Steve, I hate when I do that ! And I have done it, I've also rubbed my eye after slicing jalapeños !!!!
 
I've got a good one...

You are working with electricity and your cel phone BUZZES in your pocket...That gets you attention...LOL
 
Rob, you are very brave! I would be afraid to even look at the schematic..then again I can 't read them anyway. Man, first little crackle I would have been dialing 911 as I was running out of the house unless I had a fire extinguisher close by, then I would have sprayed it just in case, never mind trying to unplug it first! I would not want to be anywhere near anything making noise like that!
 
MusicDirector said:
Rob, you are very brave! I would be afraid to even look at the schematic..then again I can 't read them anyway. Man, first little crackle I would have been dialing 911 as I was running out of the house unless I had a fire extinguisher close by, then I would have sprayed it just in case, never mind trying to unplug it first! I would not want to be anywhere near anything making noise like that!
Click to expand...
Too funny...it DID cross my mind...is this what a tube amp fire starts like ..

So here is my baby..all put together and playing luscious tunes...

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Rob, I would love to be as efficient around my electronics as you are & hot rod them, great stuff man!
 
Hi ohbythebay, are you still around? I realize this is an old thread but I had to respond to it because I just acquired a freshly built K4040 and want to do some mods that I've found. Seems like people have been modding these amps for a long while.
Being a retired electronics tech with lots of spare time I think this will be an interesting project. Actually the mods will basically be replacing the phase splitter with a 12AT7 based one and replacing the EL34's with KT88's. The 12AU7 will also be replaced with a 12AX7.
I think the stock K4040 sounds reasonably good but there is always the hope of making it better. I feel that my custom Acoustats sound better with the TNT-200 amp that I consider my best sounding. Tubes are cool (warm?) though and I really like the looks of the Velleman. :)
 
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