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on Tue Jan 20, 2009 9:18 pm

Bob Latino

Clik2media wrote:Would you say "factory wired" are more in demand [now-a-days], than "kit" wired.... just a thought. Very Happy


If you are a "collector" of Dynaco tube gear then the factory wired version is more "collectable" and therefore worth more. From the standpoint of sound quality the sound is the same from either the kit or the factory wired unit.

Bob

on Tue Jan 20, 2009 9:08 pm

Clik2media

Would you say "factory wired" are more in demand [now-a-days], than "kit" wired.... just a thought. Very Happy

Dynaco lore - Differences between factory wired and kit built ST-70 - photos .. on Fri Dec 26, 2008 9:01 am

Bob Latino

Dynaco offered the ST-70 in both kit and factory wired versions. Although over 350,000 ST-70's were sold during the run of this amp, it is estimated that less than 5% of all ST-70's were factory wired units. Only a few ever show up for sale on Ebay. Are there any differences between the kit built units and those that were factory wired ? Although the circuit is the same there were some cosmetic and at least one one wiring difference ...

Bob

1. The wired ST-70 was called the "70-A" (A = assembled) and came with a different user manual. This 6 inch by 9 inch manual was smaller in size than the standard 8 1/2 by 11 inch manual that came with all kit amps.


2. The 70-A had its chassis components attached with rivets instead of 4-40 pan head screws. The exceptions were the front stereo/mono switch and the power switch on the rear of the amp. Reason - those two switches were threaded and the rivets wouldn't pass through the threaded hole.


3. The driver board on the ST-70-A had its own separate "driver board cage"


4. The rear of the amp had a small "factory assembled" tag.


5. The chassis had a factory installed "spanner screw" to discourage the user from removing the bottom cover. You could remove the tube cage for bias adjustments because the cage had a slot that slid over the spanner screw but in order to remove the bottom cover and get at the internal wiring you needed a spanner wrench.


6. On KIT ST-70's the assembly manual tells you to install a 1000 ohm resistor between pins 5 and 6 of each output tube. Pin 6 is not used on an EL34 and is just used as a tie off point for one side of the resistor. On the factory wired units the 1000 ohm resistor goes directly from pin 5 to the driver board and there is no connection for pin 6