ST-70s in mono?

knowledge base for the classic Dynaco ST70

ST-70s in mono?

Postby mad1 » Sat Jun 27, 2015 7:37 am

I have a couple of ST-70s and I had planned on running them as Mono blocks after some upgrades. Been reading that they don't work so well as Mono amps. Any experience you could share might just save me some time and money. I was looking to increase wattage for my ADS 1290s.


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Re: ST-70s in mono?

Postby Geek » Sat Jun 27, 2015 11:42 am


Sure they do, but the channels have to be matched perfectly for gain. This means matched tubes and sides on the driver.

You are also paralelling the channels when you go mono, so you have to double the load to get the extended power. How you do that is if you have an 8R speaker, parallel the 16R taps and add it there. If your speaker is 4R, parallel the 8R taps and put them there.

-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Re: ST-70s in mono?

Postby mad1 » Sun Jun 28, 2015 7:16 am

Thanks for the input. Feeling better about the project now
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