Ceriatone Express Questions-->Suggestions

[Blind Lemon]

Mess with the coupling cap between V1a and V2b, try a larger one there.

BL

[Subjecttochange]

I'm still having problems with it. I feel like the amp is way too overdriven at any volume. Since I don't have a real wreck to compare it to it's difficult to say, but it sounds like the preamp is screaming all the time and is becoming too saturated and unstable. Even with 2 5751s and a 12AT7. With the lower gain tubes I am also having a problem with horrible squealing- but they're known good tubes. ???

At this point I'm weighing my options. A complete conversion or rebuild will probably be in store in the near future.

If I convert it into something else- can I use the OT/PT for any other type of amp? The OT primary is pretty high at 6600 (maybe a super?) and the PT @ 300V is too low for a plexi style 50 watt right?

[Structo]

Have you tried reversing the OT primary wires?

[Subjecttochange]

You don't mean using the other Primaries right (6600 vs 5200)? You mean connecting the current left side to the right side correct? No- should I?

[Structo]

I don't know that much about Express amps but generally when an amp squeals it's an indication of phasing issues with the NFB.

Nothing to lose by trying it.

Yes just switch positions of the two primary wires on the power tubes.

[Subjecttochange]

Thanks Structo!

I opened up my amp a few days ago to switch the primaries and was quite disappointed. It was my first build (I only installed the Trannys)... and well... it was awful looking. It is kind of like discovering a huge rats nest in an otherwise beautiful house. So I think AT LEAST part of my problem is the layout. I didn't really understand the importance of wire placement when I did it and I didn't trim any leads!

...plus it just looks like crap

So- to give the express style amp a fair shot I am going to rebuild it properly- and maybe change a few values here and there to taste (reduce the gain a bit- give it some more bass). I really like all of Glen's stuff and his tone is great- but this amp was/is nowhere close.

So Question #1.
I am probably going to switch over to mustard style caps- because I love them in Marshalls that I've worked on... Plus... theres something about ODs I just don't like. Bad idea? Matter of opinion?

Q2
I'm thinking of going with Can Filter caps... Bad idea? I was thinking of JJ/Tesla 40x20x20x20 and a F&T 50x50... any thoughts? Brand preferences? I understand it will be a bit more stiff- which I tend to prefer on the performance side.

Past this stuff I will probably leave it stock and just work on the wiring/cleanliness/godliness/lead dress.

Thanks everyone for your help. You are all awesome

[Subjecttochange]

Nobody has an opinion? On a forum?

I know Dana used a 40/20/20/20 and 50/50 JJ Cap Cans on his VVR2 Express. I may just ask him his $0.02 on it.

As for Sozos or others as a replacement for ODs... suggestions? Comments? Concerns?

I just took the amp apart today- uninstalled the Trannies and power section board and took out the 1/2 power switch. I have a VVR for that instead. Now the rebuild process begins- starting with the caps. Which is why I'm here asking for a bit of wisdom.

But don't everyone go yelling at once...

[M Fowler]

If you want an express I would follow the Francesca build instructions and use the cap stack but maybe get some better caps then rebuild it like it should be. No can caps.

I have a ceriatone built by Nik and have had my share of troubles but got through it by keeping at it. Not the same issues as you I have break in shielded wire at input, changes the input jack need shielded wire, shielded wire to volume pot rearranged power wires around. Changed tone caps to .033 and tried 86k instead of 100k for NFB now back to 100k.

I will compare my in progress express build to Niks and see which one is better.

Mark

[Subjecttochange]

Thanks Mark!

I should have been more clear. I was planning on replacing the Ceriatone electrolytics with either Sprague Atoms (or equiv.) or some sort of cap cans.

I like the cans because they're clean and easy to work with... but if you and others say to hold true to the Francesca spec- I can respect that.

I am also planning on using 0.033uF tone caps. Did use them for all 4 of the 0.022uF caps? I am assuming with OD 716p? Sozo or Mallory opinions? I know it's not original- and some say Sozos are dark sounding. Frankly that's kind of the appeal to me. Plus tubeamplifierparts.com (new turretboards.com site) just started stocking 0.033uF Sozos!

[M Fowler]

I have used four types of caps, Mallory PVC, the OD, the 150s and Sozo but prefer the 150 and Sozo the best and decided those are the two that I will use from now on. My original style express uses Mallory PVC.

The Mallory PVC are used in Komet amps and TW amps which are of high quality. The Mallory filter caps is a great choice. I think they may be larger than the ceriatone caps though.

I think your right go with the Sozo caps for a darker sound and experiment with different tone caps when your done.

Mark

[Subjecttochange]

Ok cool. I ordered The Sprague Electrolytics today- along with a bunch of other crap for my 18 watt. I also got some ODs, Mallorys, and SoZos (direct) too. I'll experiment next week.

Thanks for your help Mark. I'll be posting my findings when I get there.

[M Fowler]

It will be interesting to get your view point on the changes you are making.

Mark

[NowFender]

I replaced my ceriatone express filter caps with spragues, the issue I had was that the 40uf caps didn't fit on the bottom so I switched places with 20uf on bottom and 40's on top..that's with the power supply board in, as you said you removed it and took out the trannies. I would try a dry fit first with the board in...if you have access to a variac you may want to form the electrolytics...don't know what time frame others use but went for approx. 6 hours bringing up the variac every 1-2 hours about 20 volts, amp on/standby off.

[Subjecttochange]

Ok. I just finished playing for a bit today after doing the first round of rebuild/component swaps.

So far I have changed to all SoZo caps (where applicable) and I used 0.033uF instead of 0.022uF. I also changed the filter caps to Sprague Atoms- which was a real pain since they're twice the size of the Ceriatone caps.

As far as reworking/rewiring, I uninstalled the 1/2power switch, and re-wired everything on the OT and PT since I did such a crappy job the first time around.

It does sound smoother, and has more bass- but not more bass umph (like a larger power section does). It also has decreased noise from before. It still does possess that certain sizzle sort of thing in the distortion that I find displeasing.

I think one of my biggest problems was my PI tube though- as suspected. I tried a bunch of NOS tube I had found laying around (5751, AX7, and AT7) and they all had varying degrees of microphonic or output problems. I installed some new cheapo EH12AX7s that I got for less than $10 in V2 and V3 and put in the 5751 in V1, and it sounds pretty good. I am going to have to keep on it with different tube types.

Overall I am very happy that I did the changes, and though the results aren't all as I had hoped- I've moved onto the right track and will keep experimenting with this amp instead of tearing it apart.

Got to get that VVR reinstalled too- so I don't go deaf.

Any advice on how to remedy the distortion sizzle thing or give it some more bass power would be golden.

I WILL most certainly let you know if I find/experiment with anything cool... and if I can I'll try and post a clip. My life has been a little more sad since my recording interface decided to fry itself.

[Subjecttochange]

In a higher priority than my last post... how would one go about rolling off some of the highs?