Emexar and Super 70’s Drive builds finished!

[Steve]

With the weather here in central California hovering in the triple digits for the last several weeks, I stayed in as much as possible. I’m not a big T.V. guy but do like heating up the soldering iron and melting solder. The Emexar build was completely stock but I did socket the D3 location and tried several combinations of diodes but nothing I tried was more pleasing than just having it jumped. The Super Drive 70’s was built was also stock with the exception of having 3 clipping diodes arrays to choose from. I used a DPDT (on/off/on) to accomplish this. In the center position it uses the 1N914’s located on the PCB, the top position uses 3, 1n34a’s and the bottom is a pair of 3mm red LED’s. I’m not real pleased with the 1n34a choice as there is a considerable volume drop when those are selected. So it’s back to the internet to research a better choice for that combo.

Thanks for looking!
-=SteveO

p.s. I initially had a biasing issue with Q5 but sorted that out with a quick re-flow on R24.

[Barry]

That is fantastic and thanks for sharing.

I love the builds and the artwork.

Can you upload a quality ‘straight on” shot of the Emexar for me?

The SD70’s Scooby theme is awesome.

 

I can suggest a future build for the Emexar “Ultra” by adding either a Tone TwEQ or Super Tone TwEQ in a single enclosure for some Badass riffing.

As for the SD70s 1N34A clipping diode section you can double up the 1N34As to increase the forward voltage by using the Teepee method. This will require 6 Diodes on the DPDT board or perhaps two 1N34As with a White, Blue or Green LED for asymmetrical clipping. This will get you more in the ballpark volume wise.

 

[Steve]

Thanks for the diode suggestions! That will save me a bunch of trial and error time. I have several Tone TwEQ PCB’s and 1 or 2 of the Super Tone TwEQ’s. I have not yet tried the Super Tone TwEQ so my next order I include another Emexar PCB and I’ll combo it with the Super. Here is the Emexar photo you requested. Thanks again for the support and the terrific PCB’s!!

 

p.s. I had some graphics issues on the Emexar so instead of backing up and starting over, I just gave it a little ‘distressed’ treatment.

[Steve]

I ‘teepee’d’ six 1N34a’s (as per Barry’s advice) and now I have a clipping array I can live with!!
Thanks again Barry!

[Author]

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