Dynaco Mark IV Tube mono block amplifier transformer replacement D-lab solution Hammond 273BX
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- Опубліковано 23 чер 2024
- Replacement of the main power transformer with a Hammond 273BX. Yes, it can be done with no degradation of performance. As a matter of fact, the Hammond has higher current specs. The only modification needed is for the negative bias. Vintage Fender tube amp schematics provide that information. Back in the day, power transformers did not have a bias tap, so Fender grabbed 1 of the HV windings, added a step down resistor, whamo-bamo negative bias! I adopted this method for the Dynaco. Works perfect, stable, documented. What else could you ask for. Why tear your hair out plus create a giant void in your pocked book looking for an original? The Hammond 273BX with a slight bias resistor change will solve the problem! I have included a schematic for reference. D-Lab is here to assist with these problems. If you believe in me, Please check out my Patreon: / dlab_electronics . This is all I do. Yes, the Snoz Shirts & glasses have arrived.
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Well done! Cheers Terry! This was not only a substitution suggestion, but one where the new xformer is more advantageous than the original.
Great Video - Fixing amps is my favorite content!
Elegant repair. Sounds great!
A very interesting way to put in a new power transformer that has a center tap to ground and a circuit for the negative
bias that you use for that with a simple modification. Nice.
nicely done.
Love the Snozeramous shirt!
terrific - appreciate your can-do solution. if you can find some non-copyright solo piano, it makes a good test of a hi-fi system.
Thanks! Terry🎶
very nicely done. great video.
Nice work Terry!
Well what do ya know? Just earlier today, I created a Samplewiz 2 patch based on real MK IV (Mesa/Boogie) guitar. Look into that one if you don't know it. It's a sample synth in collaboration with the extremely-gifted Jordan Rudess of Dream Theater. The company that makes it is called, "Bleass" and is French. Just wanted to also tell you that I've seen maybe about 20 of your videos here and there. You are an awesome dude. So a little of your awesome-ness back at ya, just because because if you dig what I mean. Rock on, dude!
Great video. I know it's a nitpick but I wish those transformer screws weren't so long. Trim them down and put black acorn nuts on them!
I use a Dremel tool with a reinforced cut off wheel for doing that job. Easy Peasy.
Nice !
The MKIV's are awesome amps.
Terry! Can you recommend a place to advertise two 1930-1940's console radios? They are in decent shape and ready for restoration. One is a Zenith that has a pull-out turntable in it as well as a radio that is not only AM, but Shortwave as well. Both have tube amps, the Zenith having a 15" speaker. We don't have swap meets anywhere around me (Portage, WI) that would make it worth lugging these huge things to. Any suggestions would be appreciated.
Hi Terry, if a person wanted to send you some non-working test equipment, old Heathkit units etc. The kind of rigs you like to modify to boutique amps. where would one send such a donation?
How much THD for this tube? , Bandwidth?
Are you going to build that dynaco SCA-35 on the channel?
Its a ST-70. Hopefully I can. Need a buyer first so when the build is complete it can leave.
@@d-labelectronics I misremembered it as a SCA-35 . I’m sure a NOS kit build would sell pretty quickly.