The Amp Garage

which impedance are you using for the OT primary?

Using a Hammond 125B output transformer I'm going 8 ohm speaker to secondary wires 2 and 4 for 22500 to 8.

I agree that a pentode power tube would be preferred but the very nice sounding and strong selling H&K Tubemeister 5 uses a 12BH7 power tube. I and two other builders are very happy with the clean and overdrive tone of the Deluxe Micro practice amp.

Have you ever experimented, or seen anyone else experiment with the use of two 12AU7's or 12BH7's in push/pull to get the wattage to a point that is somewhere between that of a single 12BH7 and either a pair of 6V6 or EL84? I wonder at the tonal characteristics. What is the general difference of to...

Yea, it's hard to read volts with the meter set for ohms.

Using the Deluxe, Bassman or Champ Micro As a Tube Tester The Deluxe, Champ and Bassman Micro's can use the same power and preamp tubes so all three tweed Micro amps can function as a preamp tube tester. If you do plan to use the amp as a tester then try to match V1's 100k load resistors and 1.5k ca...

I believe the bassman in the video uses the 12au7 in self-split push-pull mode which gives 1/2 half the power of a 12au7 in true push-pull mode like in the Bassman Micro.

Yes, right here: http://ampgarage.com/forum/viewtopic.ph ... 1f467d616b

Why a 5F1M Champ Micro amplifier? Because a real Champ puts out around 5 watts with it's single-ended 6V6. The Champ Micro will put out an amazing 0.75 watts of beautiful clean tweed and max out at around 1.3 watts fully distorted so it should make a good practice amp. The Champ Micro is a very simp...

Here's an updated Deluxe Micro layout:

[img882]http://robrobinette.com/images/Guitar/D ... _small.png[/img]

martin manning wrote:Where did this idea come from?

From the internet!

I obviously missed a 'minor' detail in the design of the power amp floating ground, so, ah, nevermind.

I went ahead and reverted the the classic power amp grounding scheme.

[img798]http://robrobinette.com/images/Guitar/D ... _small.png[/img]

The ' power amp floating ground' has not been implemented but now that I've looked closer I realize there is no return path for the preamp ground which attaches to the chassis at the input jack. I'll do more research and revise the schematic and layout.

Here's the updated schematic showing the "power amp floating ground."

[img798]http://robrobinette.com/images/Guitar/D ... _small.png[/img]

Sorry about the discrepancy between the schematic and layout on the "floating ground." Instead of grounding the center taps to the chassis they are connected to the power tube cathode resistor and first filter cap 'ground' connections. It's an attempt to reduce chassis eddy currents. The preamp grou...

Speaking of the 5F6A Bassman here's an annotated schematic I did with signal flow and component function:



[img814]http://robrobinette.com/images/Guitar/B ... ematic.gif[/img]