Dummy Load and H&K Red Box

[Bob Simpson]

Hi 10thTX...

I'd think bolting the O's together, ( star washer in the middle, kepz nuts )
with a few layers of heat shrink over the joints would work fine...

Or maybe run them to a barrier strip...

Good luck.

Bob Simpson

p.s. thanks for all you've done with the designs, and layouts and all...

You got any duct tape?

[Blackburn]

Or just clip off the rings and solder the leads to the plug the regular way. I just did that right now because I got tired of looking at that ugly heat shrink.

[10thTx]

Thanks for the information and help!

With respect, 10thtx

[LeeMo]

10thTx,

First, thank you for your contributions both here and on EL34 World. I am currently building a D'Mars with 6v6's and dual od. Geezers clips of his pre into the "amp - in" on another amp really got me hooked.

A few years ago , I re-built a AX84 High-Octane into a single ended Express Wreck as designed by Sliberty. https://tubeamparchive.com/viewtopic.ph ... highlight=
I put an 8 ohm sand wirewound Radio Shack resistor on the switched terminals of the output jack. The main reason was to protect the OT if I failed to provide a speaker load. I also put in a "Herzog" type line out with a level control.
After reading this thread , I decided to give it a workout. Here's the signal chain: Guitar- SE Express - line out(herzog) - TC Electronics Delay L&R out - ADA cabinet sim single rack space L&R out to Mackie 1202 mixer - headphones/ monitors.
It works " o kay" . I played with it this morning for a few min. It takes a little bit to set the gain staging and tone. I really think that it needs a reactive load on it. There is something missing in the "feel" without a speaker loading the OT.
I hope this helps you in your quest.
LeeMo

[10thTx]

Using my favorite tube amp as an "A+" reference point, I'd give this somewhere between a B to B+ and definitely falling short of an A-.

This amp was designed after my favorite tube amp (but with different power tubes, PT and OT).

I do prefer an amp somewhat pushed and hanging right on the edge of overdrive so when you dig in, it definitely has sweet harmonics and overdrives and you pick more lightly and it cleans up. This system will NOT allow you to "hang on that edge" so it's not eligible for anything in the "A" range, IMO.

Does it capture the warmth and touch sensitivity of a tube amp without using a speaker and substituting a speaker emulator. My answer is yes.

Using 6K6GT tubes with 307 volts on the plates ................. the 100w dummy resistor does NOT even get warm. In fact, it remained cool to the touch even after almost 2 hrs of playing. The 6K6GT tube are probably around 7-8 watts. My conclusion here is the dummy load resistor should be very safe for the amp & now allows the amp to be run withOUT a speaker and using a line out into the speaker emulator.

The speaker emulator surprised me in how well it worked and sounded thru the PA system. It did indeed sound very similar (not same) as a mic'd speaker. The H&K Red Box MK III has a Fenderish combo tone and a Marshallish 4X12 stack tone. I'm not real impressed with the 4X12 tone and found it too compressed. The "combo" tone is reasonably convincing & honestly exceeded my expectations. I think it's possible that someone could think it was a mic'd speaker if they could not A/B it with an actual mic'd speaker? I think I could tell an A/B difference but haven't tried that?

The amp (floor level noise) was very quiet at idle even when being played thru the PA system at volumes much louder then what would be used normally . I was concerned about typical "tube" hiss but it's looking to be a non-issue at this point.

Downside of the system ........................
I like the active FX loop dialed in at "5-7" send and "5" level. I think there is a "sweet spot" tonally there. The FX worked best in the PA system settings dialed in at "3" send and "3" level which I think lessens the sweet tone somewhat.

With respect, 10thtx