The Amp Garage

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Thanks for your replies, Martin and bepone. I actually have a couple GE 12AU7/5814As, so I will try one of them and throw the 12AT7 in the reverb driver spot. It looks like the cathode resistor value should decrease even further, to 18k or so based on Merlin’s article here: http://www.valvewizard.co...

Thanks again, Martin. I think the lower impedance makes a better driver- correct? If so, I wonder why Dumble used a 12AX7 there in the SSS. Maybe a 12AX7 was good enough and/or the bias current was limited, as you mention above.

Thanks very much for your reply, Martin. I will try that and let you know how it works out!

Hi friends, I had picked up an inexpensive Fender 75 and thought it might make a decent SSS-style platform. Its PT has a separate bias winding, so I was going to use it to supply the post-PI driver with martin manning’s voltage multiplier: http://ampgarage.com/forum/viewtopic.php?f=4&t=29882 I also ...

Parasitic oscillation, maybe? http://www.geofex.com/ampdbug/lowpower.htm

Kinda similar to OP's posts above, but could use the HAD Music Man power supply Tony posted here: http://ampgarage.com/forum/viewtopic.ph ... =music+man. This would lead to a design like the one TM had in mind here: http://ampgarage.com/forum/viewtopic.ph ... ght=driver

Hey there, Check out ElectronAvalanche's post about halfway down this page: http://ampgarage.com/forum/viewtopic.php?t=412&postdays=0&postorder=asc&start=30 He suggests values for an altered SVT driver section. It looks like HAD used his typical (give or take) long tail pair values for a PI instead ...

Well crafted; thanks for your work!

Hi Ang3lus, I attached a couple pictures I just took of the chassis: 1) marked up with the new placement, and 2) with the OT mounted as it will be on the finished amp. Even though the results from both trials were clear, I'm still incredulous... At any rate once I get the thing built I'll post the r...

I just tried the experiment again with the choke in place and the results were virtually identical to those from my first trial. I can post pictures of the final placement if anyone would find it helpful. I'll also run a build thread if folks would like to see the progress. It's a 100W high-plate sk...

Thanks for the replies, gents. I've got a little more work to do on the chassis, but before I start to populate it I will do another trial with the choke in place and post results.
Thanks again!

Hi Martin, I didn't think about that. I did not have the choke mounted when I did the experiment. The only things attached to the chassis were the PT, and OT, and the IEC connector.
I wonder if it could also be that the PT's proximity to the output tubes makes the other orientation viable...

Hi all, I'm using a CE chassis for my new build but the bracket on OT I'm using didn't fit the mounting holes in the chassis. Since I had to drill new holes anyway I figured I would use the headphone trick to inform the new OT placement. I found a very clear difference between the traditional placem...

That is a nice build!