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HEATHKIT AA-100 restored or Dynaco ST-70 Restored? Which would you take ?

Ms Doubtfire

Ms Doubtfire

New Member
Well I have the opportunity to pickup a Original Dynaco ST-70 for 450.00$ or a Heathkit AA-100 for 520$ which has also been restored . No experience with either one . Currently using a pair of 1959 H.H. Scott 99d integrated tube mono blocks. Which would you take of the two ? Just curious ? Which do you think would perform better ? I might end up buying both and just selling one or end up selling both later down the road . The Dynaco is potentially gonna come with a audio research LS-22 Tube PreAmp as well. Just wanted some folks opinion on the matter in sure some have owned them both ! Thanks
 
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Personally, I would definitely pick up the Dynaco if it's in good original condition...

I had my ST-70 restored and loved it. Had to sell it and started regretting it almost as I was posting videos to sell it. It had a a quad of original Mullard EL-34s in it, as well. Dumb...

Also, if you pick up the Audio Research preamp, you'll have separates, which is a great way to get more into the hobby! Good luck!

Edit: adding this video of the patched-together system with the ST-70 hooked up to sell. (Hold on a minute while I wipe away a tear...)

 
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+1 Thats a good deal for a restored ST-70. The thing with the ST-70 is there is more documentation, support and mods for this amp than any other ever made. Mine is a kit amp I bought from Tubes4hifi about 11 years ago.
It uses a different driver board than the Dynaco though. It still uses the same transformers, chassis, etc as the Dynaco. At that price your getting a killer deal and you can always get your money back, or even more if you don't like it.
 

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Excellent deal for an ST70, hard to find one unrestored for that kind of money…..Have said this before but it’s worth repeating, the Dynaco ST70 changes it’s sound presentation more than any tube amp I’ve come across just with tube selection.

Grab that ST70 before someone else does….

Andy
 
There was a point maybe a dozen years ago where I would've bought both. Like many I accumulated more stuff than I needed ( a fun phase all the same)
At the stated price points you should make a profit on either if you didn't like them. I always seemed to do the other way , that is buy at fair market value and sell at a discount. I looked at it as part of the cost of the hobby. ( you get to sample things you're curious about).
 
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If you can only get one, I would go with the Dynaco. If there's no money or space problem, get them both and compare and contrast in your own system.
 
All the times that I have lost my shirt in this hobby have involved tube power amps. Glorious sound but way too much $$$moke. One failure managed to bust one channel of my SS Luxman integrated, too. I'm running a 12-watt class A Chi-fi power amp now that I got new for about $300, shipped. It sounds almost as good. A do-over (well, four do-overs actually) would have saved me at least $10K that would be nice to have now. Live and learn.
 
sqlsavior said:
All the times that I have lost my shirt in this hobby have involved tube power amps. Glorious sound but way too much $$$moke. One failure managed to bust one channel of my SS Luxman integrated, too. I'm running a 12-watt class A Chi-fi power amp now that I got new for about $300, shipped. It sounds almost as good. A do-over (well, four do-overs actually) would have saved me at least $10K that would be nice to have now. Live and learn.
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I've looked into a couple myself , I like the Willsenton R8. The Boyuu A50 and Boyuu A60 .
I've really considered the Line Magnetic LM210ia 300b SET amp aswell
 
sqlsavior said:
All the times that I have lost my shirt in this hobby have involved tube power amps. Glorious sound but way too much $$$moke. One failure managed to bust one channel of my SS Luxman integrated, too. I'm running a 12-watt class A Chi-fi power amp now that I got new for about $300, shipped. It sounds almost as good. A do-over (well, four do-overs actually) would have saved me at least $10K that would be nice to have now. Live and learn.
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I have yet to Any if my tube amps or preamps fail badly. The few fails I've had have only been a couple JJ 5AR4 rectifiers, one used old stock signal tube I used that came out of some old junk I pulled it from and one power tube. That's around 10 or so power amps and around 5 or 6 tube preamps. All of them are working including those that I've passed along.
I can see how some that were produced have a history of expensive failures though.
 
Ms Doubtfire said:
I've looked into a couple myself , I like the Willsenton R8. The Boyuu A50 and Boyuu A60 .
I've really considered the Line Magnetic LM210ia 300b SET amp aswell
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Just my two cents, but I’d stay away from the chi-fi. It’s getting better, but the Dynaco is special and in five years it’ll be worth more, while the Willsenton will be worth less (and less and less). There’s something special about that vintage Dynaco iron.

I’ve also never had original vintage American tube amps give me any problems (knock on wood), while I’ve purchased three chi fi tube components and they just crapped out after not sounding very good… YMMV
 
Lavane said:
I have yet to Any if my tube amps or preamps fail badly. The few fails I've had have only been a couple JJ 5AR4 rectifiers, one used old stock signal tube I used that came out of some old junk I pulled it from and one power tube. That's around 10 or so power amps and around 5 or 6 tube preamps. All of them are working including those that I've passed along.
I can see how some that were produced have a history of expensive failures though.
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Yeah, that comment about tube amps failing, failed to mention the type and circumstances…

That’s about like saying “I got struck by lightning” so don’t go outside…I’ve only had one amp with catastrophic failure in 40 years, that was a SS class A big Denon, and I certainly wouldn’t advise anyone not to buy SS or Denon’s based on my single experience.

I’ve read that the Dynaco ST70 is the best selling amp ever regardless of type, and when one considers the aftermarket ones there’s got to be over a million sold.

Like @Lavane, never had a tube amp with a catastrophic problem, actually of the 7 around here all of them still worked in original condition when they were rebuilt, all over 60 years old.

The Chinese amps may or may not be a good buy, but the Dynaco is only going up in value, and it’s worth much more than what you listed…

VR
Andy
 
I just don't see any downside to buying a Dynaco tube amp if someone is considering it. There is so much support and documentation for them.
If you decide it's not for you, in most cases you can get back what you payed for it or more.
There are some decent Chinese made amps, but if something does go wrong later, I would expect support to be minimal.
 
sqlsavior said:
All the times that I have lost my shirt in this hobby have involved tube power amps. Glorious sound but way too much $$$moke. One failure managed to bust one channel of my SS Luxman integrated, too. I'm running a 12-watt class A Chi-fi power amp now that I got new for about $300, shipped. It sounds almost as good. A do-over (well, four do-overs actually) would have saved me at least $10K that would be nice to have now. Live and learn.
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I have a serious nostalgia Jones for tube gear, but for sheer SQ deep musical involvement with the output of vintage mid-power 12-35W tube amps, the Allo Volt+D would do quite nicely with solid state reliability @ ca $125 plus a 24VDC /5A power brick.
 
There some inexpensive worthwhile upgrades that can be done with the stock Dyna 70, one is replacing the factory board with a stuffed board using a more common 6CG8 driver tube with modern in-spec reliable components and replacing the stock value 1.5 meg on-board screen resistors with 1.2 meg. Others include the rectifier socket mod pictured, adding 100 ohm 1/4 watt screen stopper resistors to the output tubes, and a CL-90 surge suppressor on the power input side of the power transformer.
Screenshot_20240523-192038.png

Also see thread "Base line testing the Stereo 70".

Dynaco ST-70: Base Line Testing

The Dynaco ST-70 surely must represent the greatest amplification paradox of all time: It was arguably the best selling power amplifier of all time, and is arguably the most maligned such device as well. For a generation who adored it, there have been those in following generations who are quite...
audiokarma.org
 
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Pio1980 said:
There some inexpensive worthwhile upgrades that can be done with the stock Dyna 70, one is replacing the factory board with a stuffed board using a more common 6CG8 driver tube with modern in-spec reliable components and replacing the stock value 1.5 meg on-board screen resistors with 1.2 meg. Others include the rectifier socket mod pictured, adding 100 ohm 1/4 watt screen stopper resistors to the output tubes, and a CL-90 surge suppressor on the power input side of the power transformer.
View attachment 3210195

Also see thread "Base line testing the Stereo 70".

Dynaco ST-70: Base Line Testing

The Dynaco ST-70 surely must represent the greatest amplification paradox of all time: It was arguably the best selling power amplifier of all time, and is arguably the most maligned such device as well. For a generation who adored it, there have been those in following generations who are quite...
audiokarma.org
Click to expand...
That’s the truth….here’s mine pushing the Altec horns :thumbsup:
IMG_2628.jpeg
 
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