Benson Monarch

[dorrisant]

That's beautiful. I'm curious, did you try the variation on the power supply reported by Alex in his non-reverb monarch head? Did you run into any hum with the single PS ground?

Can you direct me to that variation? Do you recall the page? I may try it.

I have this separated into two ground points. The first four caps in the string are grounded right at the caps. The last cap in the string is grounded local to the preamp.

No hum really. The only trick used was heater elevation to the cathode pin of the power tubes.

I have built some very quiet amps, this one ranks right there with them. You know, you think you aren't getting anything at the speaker, even with the guitar turned up... then you hit the strings and realize how quiet it is. It is that quiet.

[CraigGa]

I've noticed that on the schematics on this thread there is no connection to ground from the HT centre tap.
When I look at 5E3 schematics the CT is grounded.

Am I missing something because I can't see a return path for the power supply?

Craig

[brewdude]

I was looking at this the other day...
I think the bridge rectifier diodes act as the artificial center tap for the filament winding.

[T Wilcox]

I've noticed that on the schematics on this thread there is no connection to ground from the HT centre tap.
When I look at 5E3 schematics the CT is grounded.

Am I missing something because I can't see a return path for the power supply?

Craig

My HT center tap is in fact grounded

[T Wilcox]

I was looking at this the other day...
I think the bridge rectifier diodes act as the artificial center tap for the filament winding.

The 100 ohm resistors after the rectifier make the artificial center tap on the filament

[T Wilcox]

Todd,
Feed that switched bypass cap with a 100k resistor from the cathode pin. That will allow the cap to voltage-load somewhat while it is disengaged. Then when you engage the switch your not suddenly switching to a different DC level... thus no popping.

Thanks I will give that a shot! It's really not a problem since I wouldn't be switching it on the fly but if that works out I might add a relay and make it a foot switchable boost.

Foot switchable boost sounds like a great idea.

Is it really this simple?

Screenshot_20210504-000000.png

I installed a stereo jack on the rear panel, used one side for the reverb footswitch like on the original monarch reverb and wired the other side the same as the schem you posted by Sluckey for the boost. Using a dual TRS footswitch it works perfectly without any added noise. I usually use a looper pedal so the boost is not that useful footswitched because it boosts my loop as well but it will be nice when I jam with some friends

[mikeywoll]

That's beautiful. I'm curious, did you try the variation on the power supply reported by Alex in his non-reverb monarch head? Did you run into any hum with the single PS ground?

Can you direct me to that variation? Do you recall the page? I may try it.

I have this separated into two ground points. The first four caps in the string are grounded right at the caps. The last cap in the string is grounded local to the preamp.

No hum really. The only trick used was heater elevation to the cathode pin of the power tubes.

I have built some very quiet amps, this one ranks right there with them. You know, you think you aren't getting anything at the speaker, even with the guitar turned up... then you hit the strings and realize how quiet it is. It is that quiet.

The conversation spills from page 19 to page 20. He posted a picture on page 20.

In short, there seem to be 3 filter nodes, 30uf -> 1k -> 50uf (20uf and 30uf in parallel) -> 11k -> 30uf. The PI and Pre amp tube both run off the third node.

Looking closer at your build that's what you did isn't it?

EDIT Nevermind, I see what you did there... snuck that last filter cap into the pre-amp.

Mike

[CraigGa]

My HT center tap is in fact grounded

Thanks for confirming that, I'll update my diagram.

Craig

[Synchu]

Completed mine as well.
Sounds very nice.
I will be posting some pics and a few sound bites soon.

Few notes:
- used 320-0-320V PT so 5R4 rectifier does the job in lowering the voltages closer to the schematic values
- adjusted the dropping string to 1k - 6.8k - 4.7k
- balanced the power amp using a scope at power tubes grids, feeding 400Hz signal to the PI input - this seems an important one to get the best out of it. Ended at 3.9k for the 10k pot.

Seems to be picky with the speakers - tried what I had - ToneTubby Ceramic, V30, T100, WGS 65, 12 C/S - sounds best with the WGS 12 C/S, but I have G12H30 on order as it seems it really needs kinda brighter speaker.

Niki

[mikeywoll]

Completed mine as well.
Sounds very nice.
I will be posting some pics and a few sound bites soon.
...

Seems to be picky with the speakers - tried what I had - ToneTubby Ceramic, V30, T100, WGS 65, 12 C/S - sounds best with the WGS 12 C/S, but I have G12H30 on order as it seems it really needs kinda brighter speaker.

Niki

It really does sound pretty good through an American "scooped" speaker. I really like the American setting at moderate gain with my WGS g12c. Great edge of break-up with a little more when you dig in.

It absolutely kills through a mismatched Greenback and G12H 2x12. Maintains the beautiful harmonic clean tone but can also do serious high gain lead and rhythm. Takes pedals really well.

Congrats on your build. Looking forward to some pictures.

Mike

[Synchu]

Here's the lovely, unpolished mess. Didn't really had a layout, just put the three strips next to the preamp tubes and went with the schematic.
It is dead silent, no buzz, hum or whatsoever with what is a pretty much standard grounding.







And a quick recording from yesterday evening. All guitar tracks - Telecaster + the Monarch, used its reverb (8FB tank) and added some other in the mix, also had a Lightspeed drive pedal on a track.
I will be looking to throw in some lead to check how it goes in the mix.
Excellent, versatile amp.

https://soundcloud.com/synchu/april-of-flourish-v1


Niki

[pullshocks]

Thanks for posting. Enjoyed the Soundcloud.

Interesting that you are using an xFBxxx tank, as I am. I ordered the "correct" xEBxxx, it should be here in a few days.

Could you elaborate on your grounding scheme? I found it hard to pick it out in the photos.

Thanks,

Mark.

[Synchu]

Thanks for posting. Enjoyed the Soundcloud.

Thanks

Interesting that you are using an xFBxxx tank, as I am. I ordered the "correct" xEBxxx, it should be here in a few days.

I don't really see how xEB is "correct"?
Swart amplifiers use very similar (if not the same) reverb arrangement with xFB, Traynor (albeit EL84 driven - same principle) and Magnatone (early models with single triode of 12AU7 driven) to name another few I didn't run the calculations, but based on these - xFB seemed like the right one from the beginning, hence that's what I ordered and installed. And it sounds quite right to my ears.

Could you elaborate on your grounding scheme? I found it hard to pick it out in the photos.

I would be sincerely amazed, if you would in this mess (PR friendly statement would be - built in the best yesteryear traditions of Magnatone, Supro, etc...) The facts are that it sounds great and is dead quiet.

Here it is in short:
Reverb driver/recovery to the common (pots) bus and input ground.
1st, 2nd and PI stages to the respective tag strips' chassis lugs.
Supply to its own tag strip chassis lug (and HT center tap goes there).
I also used the DC filaments supply for the preamp tubes and referenced it to (a separate strip chassis lug) ground via two 100R resistors (prior to the small DC rectifier, filaments transformer secondary CT is not connected).

Hope that's of some use.

Will be looking to post some single lines samples as well. To me, it's more important how the sound plugs into a full piece, but I often find that some may see single-line samples more valid.

Niki

[BobL]

I don't really see how xEB is "correct"?

This is what Benson puts in there is what he's saying.

[Synchu]

Well... then it is correct.

I think that I went through most of the thread, but I haven't seen that stated by Mr. Benson

Still think that xFB is a better fit for the circuit and intend to keep it.

EB are more suitable for op-amp (~TL072) driven circuits.

To each its own I guess.

Niki