Ceriatone Express Questions-->Suggestions

[M Fowler]

What effect does the presence circuit have as far as treble/bass is concerned as it seems to me that 100k and the .1 cap there is maybe to high as well, any thoughs out there. If you have already changed to .033 caps and may change the 500pf cap to 250pf silver mica on the board as well.

I made many of these changes and my ceriatone express is very brite even with a Les Paul. NOS tubes and matched 12ax7 or less gain tube in the PI. There has to be a reason the express is so brite. Talk about bright that new Bugera 1960 is heck of alot brighter than the express and extremely low on the other channel and jumpered about right.

I know I did not help but I have the same questions as you do, sorry.

Mark

[Subjecttochange]

Yeah... I am usually running the presence @ 0 or very close to it or I start to get a very unpleasant hiss (only when the bright switch is engaged using 500pF). I feel like something is weird with the NFB. This is the first amp I have built with NFB though, so I don't have a lot of experience with it or ways to fix/alter it.

I think the express is very barky... lots of high/mids going on. I was hoping to get it to growl a bit more. It sounds good though- but not what I was hoping for.

I will say that since changing things around- my guitar is a lot more responsive, and when I run it at 10- things get crazy and when I pull it back to 2ish- it cleans up rather well- and somewhere in between is my rhythm tone. This was not really the case before. It used to sort of clean up- it just didn't have the musical quality it does now.

Yeah Mark- please do let me know if you have any leads on what to do with the NFB deal.

Anthony

[M Fowler]

Anthony,

Since my Ceriatone Express was assmbled when I got it I did not do any voltage testing did you check your voltage chart?

I will do that and see what I get but it will be next week before I can. I have read that Nik's PT has a higher voltage than the Heyboer PT and I did change my NFB 100k to 68k and I could also try puting it on the 4 ohm or 16 ohm impedance tap to see what changes that brings. Also adjust the NFB wire away from the filter caps or move it around and see what happens.

Mark

[Richie]

if you keep the presence on 0.. you could change the feedback circuit to a resonance type control,as to add bass instead of high end..

[Subjecttochange]

I haven't done a voltage chart either...

I believe Nik uses different Iron though, and the Heyboer is much closer to original.

I may try reducing the resistor on the NFB.

Richie, how would I go about adding a resonance control? any schems or links to some info would be great!

[Richie]

http://home.comcast.net/~mamp17/Misc%20 ... 0Info.html

http://www.regiscoyne.com/tech/resonance/

you can play with the cap value a bit to see what works best..or what you like

[Subjecttochange]

Wow- thats pretty easy. I'll have to give it a try!

Thanks Richie!

[M Fowler]

Ok I changed out the 510pf silver mica cap Ceriatone has (not 500pf) for the treble to a 250pf silver mica and that gave more bass response. I think the 1 meg treble pot has to go to perhaps 500 or 250 that will be my next change. The amp is a lot better but not quite there yet.

Mark

[Tubetwang]

Cool links...

[Subjecttochange]

I'm right there with you Mark, though I will admit that it sounds sweeter and sweeter each time I play with it.

I just built an 18W and it's in the tweaking phase now... it has WAY more bass at 10 o'clock than the 'wreck clone does full up. This may have to do with my 18w circuit- but still. Having another amp to compare it to also helps in the tone selection process. I think I may try a resonance or depth type of control on the amp in the future.

Currently I am focusing my attention on polishing my woodworking skills for a jewelry box I am making for my girlfriend. I only divulge this because Trainwreck cloners choose to be multi-talented individuals who often love some fine craftsmanship both of electronics and of cabinets... not to mention exotic woods.

Maybe I'll post a pic when I finish and then get back to testing the amp out.

Let me know what else you come up with Mark/anyone

[M Fowler]

My Ceriatone Express now is in the range that I want it and for the first time sounds very good.

To recap what I did was to get rid of the very very high treble:
tone caps to .033 and the 500pf to 250pf. The NFB resistor remains with 100k as original. I did replace the input jack with the TW type and new shielded wire and did not use the 68K resistor to V1 as Nik did on his later builds. I am convinced that the 1 meg pot should be reduced as well.

The amp is way more usable with all my guitars going through 4x12 with 2 English Vin30 and 2 Carvin Vin 30. I agree darker sounding speakers would also help but I spent all my money on transformers for three new amps.

Mark

[Subjecttochange]

Thanks Mark. I am going to try out some different values with that 500pF cap when I do my next parts order. I'll let you know how the resonance control goes too- though with a lower cap value- the presence may be useful again.

I forgot to add/ask...

What tubes are you running?

I am currently using a Phillips 5751 NOS in V1, and cheapo EH 12AX7 in V2&3.

I am also running JJ/Tesla 6V6s in the Power section. To my surprise I prefer them over the Tung Sol EL34's that I have (New Production).

What do you guys think about the PI- Go with a good 12AT7?

Also- I'd rather run all current production tubes- just so I can reproduce my results down the road. I don't want to tailor the amp to NOS because there's no telling on availibility and/or price. So any current tubes you guys like?

I have used and liked the TungSols in the preamp of other amps- but I'm not so sure this is best suited for them.

Anthony

[M Fowler]

When I get home I will look as I just changed them and don't remember the brands but I am using I know GTEL34s, and GT12AT7 matched tube in the PI, a 12Ax7 in the V2 spot and 5751 in the V1 spot at this time. I haven't bothered to spend a fourtune buying NOS tubes.

I ran NOS tubes in my old Fenders for years and was happy when I could replace them with EH or Sovtek so go figure?

Mark

[Richie]

Another thing that comes to mind, that is easy, is the old fender bassmans. Some had a bass and normal channel. And some had a switch that you could flip for "Deep".. you can look at those old fender layouts and schems and see how this is done,, very easy, and fattens up the tone..

[MCK]

Currently I am focusing my attention on polishing my woodworking skills for a jewelry box I am making for my girlfriend. I only divulge this because Trainwreck cloners choose to be multi-talented individuals who often love some fine craftsmanship both of electronics and of cabinets... not to mention exotic woods.

Maybe I'll post a pic when I finish and then get back to testing the amp out.

So how? Did she say yes? I'm presuming you didn't give that box empty...