Hey guys!
I am new here, this is my first post.
So, I was looking at some old Dynaco ST-150 amplifiers. I like the old vintage look. So, I started doing some research and found mixed opinions on them. Some people say they can sound pretty nice with a few upgrades/mods. While others say they are pretty terrible sounding amps.
My first question would be, are they any good and what are the mods that will make an improvement.
My second question would be, what would be a fair price for one?
Thanks!
I am new here, this is my first post.
So, I was looking at some old Dynaco ST-150 amplifiers. I like the old vintage look. So, I started doing some research and found mixed opinions on them. Some people say they can sound pretty nice with a few upgrades/mods. While others say they are pretty terrible sounding amps.
My first question would be, are they any good and what are the mods that will make an improvement.
My second question would be, what would be a fair price for one?
Thanks!
The later version using PC-43 boards would be better. Either way, the chassis, heat sinks, and transformer would be reasonable.
You should replace the main pair of electrolytic capacitors. These sell for around $150, if working properly.
You should replace the main pair of electrolytic capacitors. These sell for around $150, if working properly.
Shipping should be nowhere near that much. Check cost with FedEx home delivery or USPS ground.
They were sold in Canada, I had one a zillion years ago. Look for one a little closer to home. You may not save much, but you could possibly avoid shipping and customs etc.
Or look for a nice refurbed Hafler DH200/220.
jeff
Or look for a nice refurbed Hafler DH200/220.
jeff
Dynaco's handling of cold idle bias current was primitive. Led to crossover distortion.
You can patch the boards with a closed loop idle bias control circuit something like "st-120 can be beautiful" thread by djoffe. I did it but found the sense transistor shorting out 3 times in 2 years. I ended up putting an Apex AX6 board in one channel, which sounded and performed fine. PCB artwork wouldn't fit in the case so I built mine point to point on bare NemaCE board. Apex AX6 solves the dynaco design problems by leaving parts out, which makes it very elegant.
Dynaco transformer is very tough. I upgraded the heat management from the inadequate dynaco ST-120 design. I got 75 w/ch out of my ST-120 for 5 seconds on SP2-XT speakers (8 ohms nominal). ST-150 has split supply, which can burn your speaker coil if one solder joint pops loose. Just like 99.99% of the other class AB amps on the market. AX6 has a $3 speaker capacitor which solves that problem without the other 15 parts (each channel) of a decent speaker protection board.
When shopping ebay or gumtree, I definitely watch shipping. From in my state, about $35 is as low as they go these days. Crossing from US into Canada you have to pay a customs loan origination fee via UPS or Fed Ex, too. Not worth it, IMHO.
You can patch the boards with a closed loop idle bias control circuit something like "st-120 can be beautiful" thread by djoffe. I did it but found the sense transistor shorting out 3 times in 2 years. I ended up putting an Apex AX6 board in one channel, which sounded and performed fine. PCB artwork wouldn't fit in the case so I built mine point to point on bare NemaCE board. Apex AX6 solves the dynaco design problems by leaving parts out, which makes it very elegant.
Dynaco transformer is very tough. I upgraded the heat management from the inadequate dynaco ST-120 design. I got 75 w/ch out of my ST-120 for 5 seconds on SP2-XT speakers (8 ohms nominal). ST-150 has split supply, which can burn your speaker coil if one solder joint pops loose. Just like 99.99% of the other class AB amps on the market. AX6 has a $3 speaker capacitor which solves that problem without the other 15 parts (each channel) of a decent speaker protection board.
When shopping ebay or gumtree, I definitely watch shipping. From in my state, about $35 is as low as they go these days. Crossing from US into Canada you have to pay a customs loan origination fee via UPS or Fed Ex, too. Not worth it, IMHO.
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Good idea, look for a Hafler amp instead. Those should be more common and cheaper (and better as-is).
Don't know if you'll like the styling, but I'm listening to a Peavey M-2600 70 w/ch amp right now on my SP2(2004) speakers. Good sounding out of the box. .1% HD cold or hot. That could be pushed down to ~.03% with a more modern op amp than TL074. Blown up M-2600s are usually $80. Search "amp for parts or repair". Damage is usually the output transistors and maybe a few drivers & VI limiter parts. Has a biig heat sink, and no fan. I've saw one in Canada 2 months ago, didn't bid because of shipping cost . CS800s or CS800x is .03% HD as is but has a fan that runs rather quietly at living room volumes.