Hello, I am new to tube amps and this forum. I have always heard that they sound richer that ss amps. I have been looking for a tube kit for some time, but happened to run into a pair of old dynakit IVs. 1950s? Both in very good condition. The first one fired up and worked fine. The other is missing the 6CA7 tubes. I noticed alot of different tubes availible, any recemendations? Should I replace all the tubes? Or if they light up, they are good? and, How bright are they supposed to get? They are pretty dim. Sry for all the questions, thanks in advance.
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dynakit mark iv
- Thread starter dk75
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Dim might be OK. You can't judge a tube by its brightness. These old tube amps are full of electrolytic caps which are probably dried out by now (50 years). They must be replaced. Expect to spend less than $100 per monoblock. Some of the film caps might be bad too - look for the black ones with the yellow stripe that say "Pyramid". There is also a selenium diode rectifier somewhere under the chassis. It looks like a double decker sandwich made of metal plates and something else. It is no longer good, and needs to be replaced with a UF4007 solid state rectifier diode. Don't be discouraged, this will be a very nice amp after you've restored it.
battradio
Electron trainer
Before you go to far , you should read some of the stikies at the top of the tube forum .
Both amps need to be recaped , and in the case of the MKIV's have the bias diode replaced with a 1n4007 diode . All electrolytic caps and the two paper caps on the circiut board need to be replaced .
Tube are a mater of taste , by a Quad of EL34's of your choice , winged c Russian or reissue mullard's would be ok .
Both amps need to be recaped , and in the case of the MKIV's have the bias diode replaced with a 1n4007 diode . All electrolytic caps and the two paper caps on the circiut board need to be replaced .
Tube are a mater of taste , by a Quad of EL34's of your choice , winged c Russian or reissue mullard's would be ok .
mcdan
Well-Known Member
I have a pair that I have restored/modded. Check this site about 3/4 of the way down the page. Used his input boards and power supply. Very sweet sounding.
http://www.dynaco-doctor.com/
Good luck.
Dan
http://www.dynaco-doctor.com/
Good luck.
Dan
I think it might be the odd looking blue cube. Check out the Mark IV assembly manual here: http://www.curcioaudio.com/Dyna MK4 Mnl.pdf
Those two orange 50 uF, 75 volt rated electrolytic caps are a critical part of the bias supply. They need to be replaced. Be aware the bias supply is a negative voltage, so you will notice those two caps have their + terminal connected to ground. Be sure to install the replacements with the same polarity. Feel free to increase the capacitance to 100 uF if you like.