express: swap the 1k/25w resistor for a choke or more?

[toobeedoobee]

I got a noisy ceriatone clone. I wonder if a choke would clean up some of the noise and I like to experiment.
Do I just replace the 1k/25w resistor for one or schould I do some more things so the same volts go to everything as before?

thx

toobeedoobee

[tubedogsmith]

If you're talking about the hiss these things make, no, it won't make any difference.

[toobeedoobee]

I should have added that I will also experiment with lead dress to denoise it.

Question remains if it's just a simple swap (resistor for choke) or if more parts need to be added or changed?

[tubedogsmith]

Yes, simple circuit swap, choke for resistor. You may want to play with the dropping string resistors afterwards. Measure your voltages before and after and adjust if necessary. You may want to take the 18k resistor to two 10k's in series. Try it and see.

[stink]

I should have added that I will also experiment with lead dress to denoise it.

Question remains if it's just a simple swap (resistor for choke) or if more parts need to be added or changed?

What kind of noise are you hearing? It may very well be a noisy V1 AND a combination of the lead wire coming off the volume pot going to V1 - ensure this wire touches NOTHING. Try tapping it with a stick and you'll see what I mean.

As far as adding a choke, you only need to drill 2 holes to mount the choke. Remove the resistor & wire the choke between the 2 posts. It's pretty simple.

-Steve
________
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[M Fowler]

I have been thinking about going with DC filament wiring to decrease the noise level has anyone done this to the Express?

Mark

[paulster]

I have been thinking about going with DC filament wiring to decrease the noise level has anyone done this to the Express?

What noise are we talking about here? If it's the inherent Express hiss then DC filaments aren't going to solve that.

I use DC (preamp) filaments in all my amps as a matter of course, but that's only to ensure that there isn't any 50/60Hz hum introduced by the filaments. This is a wholly different issue to the typical white noise you get in an Express though, and good lead dress should ensure that filament hum isn't really audible anyway.

[M Fowler]

I have not tracked down what is causing the noise in my Ceriatone Express, which I did not build. I have been talking with Nik about it. I made a bottom plate, I checked for lead dress, I tried Niks 15k resistor from the input jack to pin 7 and it still is one noisey amp. I replaced all the tubes and no luck. The liverpool I built does not have these problems and I hope my Rocket doesn't either. So one of these days I will find the source. There is a ground loop problem in my Express, not sure what problems toobeedoobee is having with his amp.

Mark

[novosibir]

As I already wrote in another topic I really can't recommend to reduce the supply voltage difference between the plates and screens in an Express by using a choke!

The 'Express Sound' partial benefits from the extreme mismatch of the OT's primary impedance, when EL34's are used (6.6K instead of ~3.5K).

But this mismatch wouldt be an extreme stress for the screen grids, if the screen voltage wouldt be close to the plate voltage - what is the case, if you swap the 1K with a choke!

Larry

[iwo]

I have ceriatone clone of express and I ordered it with a choke first. The amp was very noisy and humming in my home but as I plugged it in a place with a proper AC grounding most of the hiss and hum disappeared. About half years ago I tried the resistor in place of the choke and I didn't notice much difference in hiss or sound. But my case is not that transparent as I use different cabs all the time but in my case what had most effect was proper grounding from the wall outlet.

[iwo]

I have ceriatone clone of express and I ordered it with a choke first. The amp was very noisy and humming in my home but as I plugged it in a place with a proper AC grounding most of the hiss and hum disappeared. About half years ago I tried the resistor in place of the choke and I didn't notice much difference in hiss or sound. But my case is not that transparent as I use different cabs all the time but in my case what had most effect was proper grounding from the wall outlet.

[toobeedoobee]

Thank you for all the replies so far

The noise I have is white and loud, a lot of hissssssssssss just a little hum but noting too bad.

I have shielded guitars with humbuckers good ground in my musicroom and the hiss is there with all tubes I tried, tubes that don't hiss in other amps.