The Amp Garage

Miket · Joined: 22 Jun 2012 Posts: 23

Yes I am also interested in this. Seems like a good start for a first trainwreck build

M Fowler · Joined: 16 Jan 2008 Posts: 8553 Location: MN

Yes the PCB to me was very simple to build and sounded good on first fire-up.

We will have to wait and see what rj wants to do regarding offering at least the boards.

Mark

RonnieJ · Joined: 28 Jun 2012 Posts: 2

rock_mumbles · Joined: 17 Nov 2008 Posts: 113 Location: Podunk, Idaho

That's being worked on over here ...
http://ampgarage.com/forum/viewtopic.php?t=18831

Koop · Joined: 10 Jan 2011 Posts: 72 Location: Shelby Twp, MI

In these photos I see what appears to be the 1k 25 watt resistor mounted to the chassis with screws. The only 1k 25W I have is a cement type, no metal housing or any way to fasten to the chassis. What is the best way to install this in the revised PCB build?

M Fowler · Joined: 16 Jan 2008 Posts: 8553 Location: MN

Koop either get the metal base 1k/25w resistor or make a small eyelet or turret board and place the board on the right side of your output jacks in that bare space on the back panel.

See the red board in my 18w amp.

Koop · Joined: 10 Jan 2011 Posts: 72 Location: Shelby Twp, MI

Thanks Mark, I'll rig up something similar.
EDIT - I decided to order aluminum housed resitors from Digi-Key since I could use a couple of other items as well. My $11 order will probably cost $20 by the time it ships!

dorrisant · Joined: 21 Sep 2010 Posts: 335 Location: Evansville, IN

Just a little update...

After a few months of breaking-in, my PCB Express is very quiet and stable... quieter than any of the Fenders or Marshalls that make their way through here, but not quite as quiet as my Rockster.

It is very sensitive to any vibration applied to the chassis. You can hear the mechanical snap of the bright switch through the amp. It is not a bad thing as long as it is isolated from any vibration. I usually sit it up on a pillow (must find a cooler method), and never on top of the speaker cab. We discovered a weird octave thing going on one day at a show... it was picking up the vibe from the cab resonance. Put it on the floor and it went away. I was aware of this possibility and it wasn't that big of a deal.

Just saying this because even though this is a very stable way to build this circuit you can still pick up funny noises if you don't pay attention to noise/vibration sources.

That said, this amp sounds gorgeous, clean all the way to flat gettin' it. The only complaint from anyone is that it is too loud as is... so I pass out earplugs!

Thanks and best wishes to rj!

Tony

M Fowler · Joined: 16 Jan 2008 Posts: 8553 Location: MN

M Fowler · Joined: 16 Jan 2008 Posts: 8553 Location: MN

Tony,

Glad your amp is working out so well except for the fan earplugs hard to put your band logo on such a small item. Smile

Better go with Vulcan ear type.

Still the PCB type layout to me was such an improvement for stability. To eliminate what your going through I had to use lower gain tubes it's a must for most situations. Better get one of those garden knee pads to use between the head cab and speaker cab. Smile

Mark

dorrisant · Joined: 21 Sep 2010 Posts: 335 Location: Evansville, IN

Thanks Mark.
That is a good idea... I'll have to look for something like that. Much more low-profile than a over-stuffed throw pillow!

I am still thinking of using ampdoc's idea of attenuation via dropping power tube heater voltage. I tried this with a huge variable resistor and it worked but is too large to fit in most amps. I may have to get a VVR from Dana to do the scaling... just on that heater voltage.

Has anyone tried this?... just looking for a starting point. Seems like someone did... Hans maybe?
I have never even used VVR before. I know how it works but getting it to scale the smaller voltage and rectifying it to dc are two issues to address.

Tony