Benson Monarch

[CraigGa]

You're better than me at deciphering Mike but I'm better at getting the good photos

I notice that there's no DC heaters though.

Craig

[mikeywoll]

You're better than me at deciphering Mike but I'm better at getting the good photos

I notice that there's no DC heaters though.

Craig

You have that super computer from the year 2019 doing all the hard work for you!

Funny how the D/C heaters just quietly went away.

[CraigGa]

Funny how the D/C heaters just quietly went away.

I think the one Aaron had on his bench had a fault with them.

Craig

[mikeywoll]

Funny how the D/C heaters just quietly went away.

I think the one Aaron had on his bench had a fault with them.

Craig

There's a gut shot of a head (without reverb) for sale on Reverb too. Looks like 56K on the first plate. 5.6K on the split-load 2nd plate and there are 4 PS nodes. No labels, but based on size looks to line up with Chris Benson's description (22uf,47uf and a 2x can that's likely F&T 32 or 16uf?). Also A/C heaters

[mhat]

I re-did my build with the 5 filter caps/nodes. It's certainly way quieter on the hum side but now also way quieter overall. I can put the volume on max and the volume level matches the output of my Princeton Reverb around 3.5 I'd guess. Sound more lifeless vs when I first built it and had the reverb hum and signal bleed through on zero. I uploaded a shot of chassis. I was limited on size and was only planing on 4 nodes originally so it's crammed. I drew some illustration arrows of my dropping resistors. I went with 1k->4.7k->4.7k->4.7k based off the recent Monarch Reverb shots I saw off Reverb.com. I also swapped out the 10k/100k split plate resistors for a 4.7k/100k on V1. Any thoughts?

Voltages
V1
1 - 183.4V
3 - 1.69V
6 - 188.5V
8 - 1.39V

V2 (reverb)
1 - 253.6V
2 - 182.8V
3- 191.4V
6 - 89.9V 181.6
8 - 83V

V3 (PI)
1 - 169.9V
3/8 - 1.06V
6 - 174.3V

V4/V5 (6V6)
3-335.5V
4 -324.6V
8- 20.18V

[mikeywoll]

I re-did my build with the 5 filter caps/nodes. It's certainly way quieter on the hum side but now also way quieter overall. I can put the volume on max and the volume level matches the output of my Princeton Reverb around 3.5 I'd guess. Sound more lifeless vs when I first built it and had the reverb hum and signal bleed through on zero. I uploaded a shot of chassis. I was limited on size and was only planing on 4 nodes originally so it's crammed. I drew some illustration arrows of my dropping resistors. I went with 1k->4.7k->4.7k->4.7k based off the recent Monarch Reverb shots I saw off Reverb.com. I also swapped out the 10k/100k split plate resistors for a 4.7k/100k on V1. Any thoughts?

Voltages
V1
1 - 183.4V
3 - 1.69V
6 - 188.5V
8 - 1.39V

V2 (reverb)
1 - 253.6V
2 - 182.8V
3- 191.4V
6 - 89.9V 181.6
8 - 83V

V3 (PI)
1 - 169.9V
3/8 - 1.06V
6 - 174.3V

V4/V5 (6V6)
3-335.5V
4 -324.6V
8- 20.18V

Those voltages don't look bad. I'm guessing you have a bad solder joint or short somewhere in the signal path. What you are describing isn't expected. Mine is as loud or louder than my other two 15 watters.

Hang in there... Troubleshooting a bad solder joint can be maddening.

[mikeywoll]

I re-did my build with the 5 filter caps/nodes. It's certainly way quieter on the hum side but now also way quieter overall. I can put the volume on max and the volume level matches the output of my Princeton Reverb around 3.5 I'd guess. Sound more lifeless vs when I first built it and had the reverb hum and signal bleed through on zero. I uploaded a shot of chassis. I was limited on size and was only planing on 4 nodes originally so it's crammed. I drew some illustration arrows of my dropping resistors. I went with 1k->4.7k->4.7k->4.7k based off the recent Monarch Reverb shots I saw off Reverb.com. I also swapped out the 10k/100k split plate resistors for a 4.7k/100k on V1. Any thoughts?

Voltages
V1
1 - 183.4V
3 - 1.69V
6 - 188.5V
8 - 1.39V

V2 (reverb)
1 - 253.6V
2 - 182.8V
3- 191.4V
6 - 89.9V 181.6
8 - 83V

V3 (PI)
1 - 169.9V
3/8 - 1.06V
6 - 174.3V

V4/V5 (6V6)
3-335.5V
4 -324.6V
8- 20.18V

Missed it the first time. You should have 0.83 not 83 volts on your reverb recovery cathode. Something is up there.

[brewdude]

If you change the 10k/100k split plate to 4.7k/100k you have effectively halved the signal going to the next stage. The split load behaves like a voltage divider and could account for the change in volume and feel.

[mhat]

I changed the Split plate back to 10k/100k and it's definitely louder now, but I'm still not loving the output. I'm going to go back and look things over.

Oh, and I forgot my decimal on the Reverb, it was .83V, not 83V. I did switch to 100K on the Reverb plate. It matches the newer guts shots of the Monarch Reverb I posted. Of course so does the 4.7k/100k split, and I hated that. I'll play around with it.

[mikeywoll]

I changed the Split plate back to 10k/100k and it's definitely louder now, but I'm still not loving the output. I'm going to go back and look things over.

Oh, and I forgot my decimal on the Reverb, it was .83V, not 83V. I did switch to 100K on the Reverb plate. It matches the newer guts shots of the Monarch Reverb I posted. Of course so does the 4.7k/100k split, and I hated that. I'll play around with it.

That's probably one issue... The reverb plate load resistor is laying flat across the tube socket. What you are looking at there is the cathode resistor for the reverb driver.

[CraigGa]

So my build is up and running, I've done a few tweaks and settled on the 4k7 split load resistor which can be clearly seen in the recent pictures.
My only issue is a tendency to get a bit flubby if driven too hard with a neck humbucker, clean it's not too bassy at all just when driven. Where should I be looking to tweak that? output tubes cathode cap possibly?

I did build it with the smaller PI coupling caps so it's not that.

Thanks
Craig

BTW there's some pictures here
https://ampgarage.com/forum/viewtopic.php?f=6&t=34820

[TUBEDUDE]

I'd replace the humbucker with a single coil. Failing that, increasing your grid stopper values, or larger filter cap values maybe. Can you see what stage is the issue?

[CraigGa]

I'd replace the humbucker with a single coil.

That would eliminate the need for more than one guitar

Failing that, increasing your grid stopper values, or larger filter cap values maybe. Can you see what stage is the issue?

When I was scoping around in there I saw that the PI is the first stage to overdrive so I would suspect that or the output stage.

Craig

[mikeywoll]

I'd replace the humbucker with a single coil.

That would eliminate the need for more than one guitar

Failing that, increasing your grid stopper values, or larger filter cap values maybe. Can you see what stage is the issue?

When I was scoping around in there I saw that the PI is the first stage to overdrive so I would suspect that or the output stage.

Craig

The British/American switch seems to be tailor-made to address this issue? I find the low end in the American mode to be wild, almost like a fuzz when driven hard. In the British mode it's much tighter and better suited for heavy drive. I think it's sort of by design.

If you find it too flubby in the British mode, I would look at that first stage coupling cap or cathode bypass cap. Especially if you have more gain coming out of that first triode due to moving its place in the power supply (not sure if you stuck with that change).

Mike

[CraigGa]

First things first Mike,

Is US mode with just the cap or the cap and resistor?
I could never be sure of that but figured US was the brighter of the two options.

Craig