Input regarding possible mods

[jckid649]

Sorry if I was a bit harsh in my prior reply. It just struck me SO odd for an Express to have too much low end with the bass knob off. That really makes me question something may have been missed and I'd truly search high and low throughout before I'd start any mods. Like I mentioned you also might want to check your pots, because if you have pots that come on too quickly a basic setting of all knobs on 1/2 could be totally different and much gainier than expected. For example if one built a TW with linear taper pots you would probably need to have the volume, treble, and bass pots set on just "1" to get the same sound a TW running slow analog taper pots with everything on 1/2. Slow taper meaning about 10%, where "1" on the dial would be about 100k or 10% of the full 1meg value.

I have the pots that came with the ceriatone kit and I'm not sure which are audio and which may be linear. Which ones are supposed to be audio and which linear? Where is a good source? I know a good seller who sells matched tested sets of mil spec pots.

[RJ Guitars]

If you can find the source of that extra bass it would be of great interest to many of us here. The Express is the amp you use to cut through the mud of a loud band and lots of stage noise so it also sounds unusual to me to have excess low end. I'm not sure I would add any additional low end to my Express builds but I can imagine a few cases where if it was an option I might find a use for it.

Most folks who talk about swapping out the transformers in a Ceriatone usually report back that the amps get smoother and sweeter tone.

Is your amp tech familiar with the Express Amp? For myself and many others I had to actually acclimate myself to using this amp. The huge gain and aggressive bite of these amps required me to learn how use a soft picking touch and the volume control in a whole new way. I also have never used mine with the volume set above 6 or 7 except just to prove to myself that it remained stable when it was totally cranked... it didn't sound it's best dimed out though.

Let us know what you find. I think the Express schematic listed as "the schematic" in the "Trainwreck Files" shouldn't give you excess bass so I'll be curious what you find.

rj

[jckid649]

If you can find the source of that extra bass it would be of great interest to many of us here. The Express is the amp you use to cut through the mud of a loud band and lots of stage noise so it also sounds unusual to me to have excess low end. I'm not sure I would add any additional low end to my Express builds but I can imagine a few cases where if it was an option I might find a use for it.

Most folks who talk about swapping out the transformers in a Ceriatone usually report back that the amps get smoother and sweeter tone.

Is your amp tech familiar with the Express Amp? For myself and many others I had to actually acclimate myself to using this amp. The huge gain and aggressive bite of these amps required me to learn how use a soft picking touch and the volume control in a whole new way. I also have never used mine with the volume set above 6 or 7 except just to prove to myself that it remained stable when it was totally cranked... it didn't sound it's best dimed out though.

Let us know what you find. I think the Express schematic listed as "the schematic" in the "Trainwreck Files" shouldn't give you excess bass so I'll be curious what you find.

rj

I'm thinking that the problem lies in the pots...I did have the midrange pot short out awhile back and I could have poor quality pots. I would like to know which pots are linear and which are audio and a good source to buy high quality and type of pots.

He is not familiar with the Express Amp. So he found a lot of things very strange and counterintuitive.

I cannot say what the issue is but it seems sort of muffled right now. I do believe it's a pot issue.

[sliberty]

I'll just add my 2 cents to what others have said.

A properly working Express is a little weak on the bottom end, so something is not working in your map the way it works in virtually all other Express clones.

The mods your tech has proposed may have some useful impacts, but I personally wouldn't make any mods until I figured out and corrected the bass issue.

Even then, most of those changes appear to be to drastic in my book. if you want to reduce the gain (which I also wanted to do on my Express), there are much simpler ways to do it, which will have less of an impact on the overall character of the amp. If you make the changes your tech proposed, it really wouldn't be much of an Express anymore. You might like it, but it would be something else really.

Many have indicated that the Ceriatone iron doesn't sound much like Express iron - more Marshally. I have no idea whether or not this is contributing to the overly bassy voicing. But just keep it in mind.

I imagine if you posted a bunch of detailed photos, some guru here would notice if anything obvious was wrong.

Good luck!

[geetarpicker]

The Ceriatone iron is definitely louder, brighter, and a little harsher than the Pacifics. I once put 6V6s in a Ceriatone to tame it down and it was STILL louder than my Pacific transformer original is with EL34s! That said if one was looking for more of a JCM800 grind (and Marshall 50w impact) out of an Express the stock iron might suit them fine.

[geetarpicker]

In a stock Express the middle (25k) and presence (5k) controls are linear, and the other 3 are (1 meg) audio taper. I'm not sure what to recommend in new pots, but try to find some 1 megs that taper up no faster than just 10% (100k) at mid rotation. This will make finding the sweet spot on the controls (especially the volume) much more easy to find, as it simply spreads out the usable range of the controls.

[jckid649]

In a stock Express the middle (25k) and presence (5k) controls are linear, and the other 3 are (1 meg) audio taper. I'm not sure what to recommend in new pots, but try to find some 1 megs that taper up no faster than just 10% (100k) at mid rotation. This will make finding the sweet spot on the controls (especially the volume) much more easy to find, as it simply spreads out the usable range of the controls.

so if the mid is linear then it shouldn't cut when fully dialed counter clockwise to 0 but the treble and bass should cut at 0? I notice that all of them cut at zero including the mid. Perhaps my mid is an audio taper...hmm

[geetarpicker]

Try measuring the pots with them on 1/2, going from the center terminal to either outside leg. On the Linear pots you should get close to 50% of the rated ohm value either way. On the analog taper 1 megs you (optimally) should get maybe 100k of one leg, and 900k off the other. To get accurate readings you may need to completely disconnect them from the circuit to test. This test is a very rough and dirty way to see what sort of taper your pots have.

[M Fowler]

Weber has 20% taper pots.

[jckid649]

Try measuring the pots with them on 1/2, going from the center terminal to either outside leg. On the Linear pots you should get close to 50% of the rated ohm value either way. On the analog taper 1 megs you (optimally) should get maybe 100k of one leg, and 900k off the other. To get accurate readings you may need to completely disconnect them from the circuit to test. This test is a very rough and dirty way to see what sort of taper your pots have.

Thanks I will definitely do some measuring and searching for 10% taper pots. Or at least as close as I can find.

[jckid649]

Weber has 20% taper pots.

I'll check those out. Thanks.

[jckid649]

Weber has 20% taper pots.

What's the difference between low, standard, and high rotating friction pots? That's the options weber has.

[Zippy]

I haven't seen mention of what guitar the OP is using. What pickups?

[jckid649]

I haven't seen mention of what guitar the OP is using. What pickups?

I use both a Les Paul Custom with '59 style wiring and Seymour Duncan PAFs that are a little hotter than the original '59s. Also, I have a Fender Strat with '50s style wiring and reverse stagger Jimi Hendrix style pickups.

[M Fowler]

Weber has 20% taper pots.

What's the difference between low, standard, and high rotating friction pots? That's the options weber has.

The 20% pots are under guitar pots but they have some with solid shaft that will work with TW knobs. The serrated shaft would work with TW knobs too.

Rotating friction is the ease of knob rotation. Some pots like Bourns are hard turning while Alpha seem to turn like greased lightning. (low friction).