First build crackle n pop.. benson monarch.

[unknowntome]

…
So I just ran the experiment.

Pulled out V3 - shhhh persisted. Reinstalled.
Pulled out V2 - shhhh stopped. Reinstalled.
Pulled out V1 - shhhh stopped. Reinstalled.
…

It may be helpful to clarify that V3 looks to be the reverb circuit, rather than the phase splitter, which is not what might usually be inferred from the terminology.

Yes that’s correct, V3 is the reverb circuit.. is there something else re phase splitter I ought to be considering?
Cheers!

[unknowntome]

So after poking about a changing the 470k resistor from CC to CF connected to the tone switch the hiss still remains

Whilst chop sticking around I discovered that the .022 capacitor connect to V2 pin2 is ultra sensitive when tapped.. the sound comes through the speaker.. is this normal??

[unknowntome]

So after poking about a changing the 470k resistor from CC to CF connected to the tone switch the hiss still remains

Whilst chop sticking around I discovered that the .022 capacitor connect to V2 pin2 is ultra sensitive when tapped.. the sound comes through the speaker.. is this normal??

Wondering whether the microphonic capacitor could be contributing to the hiss at all?? Perhaps amplifying the noisy character of the carbon comp resistors around it??

[unknowntome]

Still no luck in trouble shooting the hiss…

Here’s what I’ve done so far:

Changed plate and grid resistors from CC to CF.
Also changed input resistor to CF.
Reduced input grid resistor to 33k CF.
Used shielded wires for most signal paths.
Tested different tubes.
Tested capacitors on the tube sockets without luck.

Things I’ve observed:

Volume and tone knobs have no impact on the nature if the hiss.
There’s a microphonic coupling cap (V2 Pin2) that’s very sensitive to touch.
There’s also a microphonic wire connected to the tone switch that’s sensitive to touch.

Here’s a short video snippet of what the hiss sounds like.. not sure if it’s RFI if not??!

https://youtube.com/shorts/e1MbHFpxfLk?feature=share

[CraigGa]

The video comes up as private for me.

Craig

[unknowntome]

The video comes up as private for me.

Craig

Just fixed it

https://youtube.com/shorts/e1MbHFpxfLk?feature=share

[unknowntome]

UPDATE

So, I changed all the CC resistors connected to V1 and V2 as well as the input and tone resistors and the hiss has essentially vanished! It was until I changed the final 3 resistors circled together that the hiss vanished. Wondering whether it was because of changing all the CCs or perhaps it was one if the three??!! Who knows

[TUBEDUDE]

Carbon resistors are noisy. The worst place to use them is V1. The noise gets amplified the most. Vintage purity warriors must have them though.

[unknowntome]

Carbon resistors are noisy. The worst place to use them is V1. The noise gets amplified the most. Vintage purity warriors must have them though.

Yes, I’ve discovered that the hard way!

[T Wilcox]

Weird I've built 2 of these Monarchs with all CC resistors just like the originals without any hiss or noise issues at all
Glad you got rid of the noise though as that's all that matters

[unknowntome]

Weird I've built 2 of these Monarchs with all CC resistors just like the originals without any hiss or noise issues at all
Glad you got rid of the noise though as that's all that matters

Hey Wilcox
Yeah that’s interesting… all this stuff online about the noise when using CCs.. it happened in my build! .. then there are experiences like yours! There’s still the slightest crackle when cranked (so slight.. totally fine) so I suspect it’s the 3 leftover CCs in the reverb circuit I haven’t changed.. and won’t!

[T Wilcox]

Hey Wilcox
Yeah that’s interesting… all this stuff online about the noise when using CCs.. it happened in my build! .. then there are experiences like yours! There’s still the slightest crackle when cranked (so slight.. totally fine) so I suspect it’s the 3 leftover CCs in the reverb circuit I haven’t changed.. and won’t!

Keep in mind the originals all use CC resistors and do not have any noise issues that I know of as well.
I would look elsewhere for the crackle problem if it persists but I also don't think it will hurt to change them out and see

[dorrisant]

I built mine point to point with all CCs in the signal path and it is very quiet. The fact that it is point to point may be the difference. I have built a bunch of (30-40) tube mic pres using the p2p method as well as hundreds of rebuilds on very old (30's) units and never had an issue with hiss or any other noise. Although, in most of these I used MF for the plates.

[unknowntome]

Hey Wilcox
Yeah that’s interesting… all this stuff online about the noise when using CCs.. it happened in my build! .. then there are experiences like yours! There’s still the slightest crackle when cranked (so slight.. totally fine) so I suspect it’s the 3 leftover CCs in the reverb circuit I haven’t changed.. and won’t!

Keep in mind the originals all use CC resistors and do not have any noise issues that I know of as well.
I would look elsewhere for the crackle problem if it persists but I also don't think it will hurt to change them out and see

The thing is the 'shhhh' went away went I changed those final 3 CC resistors I circled a few posts back... takes me wonder was it one of those and not the rest?!?!

[unknowntome]

I built mine point to point with all CCs in the signal path and it is very quiet. The fact that it is point to point may be the difference. I have built a bunch of (30-40) tube mic pres using the p2p method as well as hundreds of rebuilds on very old (30's) units and never had an issue with hiss or any other noise. Although, in most of these I used MF for the plates.

The first resistor I changed was the 100k connected to pin1 V1 and the crackle disappeared instantly. Then changed the plate and grid resistors from CC to CF.. without luck.

One final issue is the amount of noise coming through my guitar when I move the amp from my workshop into the lounge room. the noise increases is effected my the volume and tone knobs on the amp... completely disappears as I roll the volume back on my guitar. Amp is pretty much dead silent when guitar is unplugged or the volume is rolled down.