Hi, I was just offered to go look at a Dynakit Mark iii that was built by an EE that passed away recently. His wife is 90 years old and looking to sell off a bunch of electronics and machines that he gathered over time.
This is ironic timing because I was just ramping up for a tube build/design for a specific purpose, and planned to make a Dynaco type amp the starting point of sorts.
I was curious of anyone know a bit about these and especially the quality of the transformers, if they are manufactured by the same source as the Dynaco replacements like we see at Triode Electronics. Of all the internet searching I just did, there didn't seem to be much said about the source of the transformers and other components, just that the kit was pretty good of itself. I have no idea what brands of tubes it has (only was sent an image from a distance).
Of course, its difficult to make an offer to someone that doesn't know anything about it, along with myself not knowing yet what condition the transformers, tubes and components are in. I may ask her to let me take it home to inspect and test things, and give her a deposit. She knows the same people I do so hopefully I'll be trusted to take it along for a closer look. I'd hate to give her alot of money and come home with open primaries, taps and roasted filaments.
Thanks, any input will be welcome.
Best,
Phil Donovan
This is ironic timing because I was just ramping up for a tube build/design for a specific purpose, and planned to make a Dynaco type amp the starting point of sorts.
I was curious of anyone know a bit about these and especially the quality of the transformers, if they are manufactured by the same source as the Dynaco replacements like we see at Triode Electronics. Of all the internet searching I just did, there didn't seem to be much said about the source of the transformers and other components, just that the kit was pretty good of itself. I have no idea what brands of tubes it has (only was sent an image from a distance).
Of course, its difficult to make an offer to someone that doesn't know anything about it, along with myself not knowing yet what condition the transformers, tubes and components are in. I may ask her to let me take it home to inspect and test things, and give her a deposit. She knows the same people I do so hopefully I'll be trusted to take it along for a closer look. I'd hate to give her alot of money and come home with open primaries, taps and roasted filaments.
Thanks, any input will be welcome.
Best,
Phil Donovan
The Dynaco transformers were made by Tresco in Philadelphia.
Unsurprisingly David Hafler also owned stock in Tresco.
Make sure that it's a MkIII, not a MkII. These amps originally sold for less than $100 each.
You should discard everything except the chassis, transformers, and choke.
Make sure the selenium rectifier has not failed and deposited material inside the chassis.
Also this amplifier is now available new as: MARK III KIT (120 VAC) - Dynakit Parts
Unsurprisingly David Hafler also owned stock in Tresco.
Make sure that it's a MkIII, not a MkII. These amps originally sold for less than $100 each.
You should discard everything except the chassis, transformers, and choke.
Make sure the selenium rectifier has not failed and deposited material inside the chassis.
Also this amplifier is now available new as: MARK III KIT (120 VAC) - Dynakit Parts
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It's probably unlikely that there's anything wrong with the transformers, but you never know. Most likely these amps were build in the late 50's when the MKiii's were a new thing, and the EE was young. At this point they will need a resto, with new caps, tubes etc. Do a bit of research as to what an unrestored pair are worth.
jeff
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Do some research on West and Sunn guitar and bass amplifiers.
Both manufacturers used Dynaco power amplifier circuits and transformers (MKIII, MKIV and MKVI) in their products, coupled with their own preamp circuits.
If they could handle Credence Clearwater Revival and Grand Funk Railroad playing on the road, I don't think there's much to worry about😎
Both manufacturers used Dynaco power amplifier circuits and transformers (MKIII, MKIV and MKVI) in their products, coupled with their own preamp circuits.
If they could handle Credence Clearwater Revival and Grand Funk Railroad playing on the road, I don't think there's much to worry about😎
As for the "new manufacture" of Dynaco transformers, I will say that the Z565 output transformers that I've gotten through Triode Electronics are definitely worth the price.
You're out of your mind. My 1961 ST70 is fine. selenium rectifier replaced with 1n4003 about 1978.
Electrolytic caps deteriorate. Carbon comp resistors over 100k have more hiss than metal film resistors. Paper plate caps have a certain sound, which is not copied by mylar. Dynaco used mil-spec equivalent resistors, which had the paint that did not allow moisture inside. AB or Sprague.
I've got ~60 1961-68 vacuum tubes in the ST70 or Hammond organs that are fine, including the 5AR4 rectifiers. Rectifiers & output tubes do get tired at 8000-15000 hours use. check B+ voltage at maximum volume, and if fine, then AC v out on 8 or 4 ohms. P=(V^2)/Z where p is power and Z is speaker impedance. Power low and B+ near spec, then the output tubes could use freshening. I've never replaced the input tubes. I used my ST70 2000 hours/year 1970-1980. 3 sets electrolytic caps, 2 rectifier tubes, 2 sets output tubes. Tubes got impossible to get 1980-2006. If you live in nowhere as I have.
I've seen burnt looking ST70's on ebay for $600. For parts or repair. Working ones go a lot more. Mk III has more power than one channel of ST70.
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They beat me to it damn it
Thank you all for coming to my aid.
As it turned out some people came from Connecticut a half day before I was able to get to the house. they go the 2 Dynaco's. Man, I hadn't known a bad mood like that in a long, long time. The early bird does get the worm.
However, I did make off with more than a few things
Old Realistic tube amps made by Gommes LJ-2, and a few other pieces of preamps and FM recievers that still had NOS RCA, Sylvania Tung Sol, and some fairly hefty transformers (of course will have to test separate components to assess function).
And also, 2 Lexicon 300 reverb racks and tomorrow I'm going to make an offer on a Lexicon 200. The 300 are the latest version 3.5 chipset. I plan to keep one of the Lexicon 300's and sell the other 300 and 200 at current used prices, offers. But man, those KT88 amps were sounding like something to dig the teeth into. I had plans for those.
thanks again for your feedback. I won't be holding my breath that a Dynaco opportunity like this will come marching along too soon!
Best,
Phil Donovan
Thank you all for coming to my aid.
As it turned out some people came from Connecticut a half day before I was able to get to the house. they go the 2 Dynaco's. Man, I hadn't known a bad mood like that in a long, long time. The early bird does get the worm.
However, I did make off with more than a few things
Old Realistic tube amps made by Gommes LJ-2, and a few other pieces of preamps and FM recievers that still had NOS RCA, Sylvania Tung Sol, and some fairly hefty transformers (of course will have to test separate components to assess function).
And also, 2 Lexicon 300 reverb racks and tomorrow I'm going to make an offer on a Lexicon 200. The 300 are the latest version 3.5 chipset. I plan to keep one of the Lexicon 300's and sell the other 300 and 200 at current used prices, offers. But man, those KT88 amps were sounding like something to dig the teeth into. I had plans for those.
thanks again for your feedback. I won't be holding my breath that a Dynaco opportunity like this will come marching along too soon!
Best,
Phil Donovan