My First Post on The Amp Garage: PT's OT's and Ceriatone

[ergotrons]

Gday all from Brisbane, Australia,

This is my first post here and I have a few questions about kits.
I've been mucking around with fixing, modding and building amps on a hobby basis for a few years now, but I've only recently been reading up about the Dumble ODS style amps.

As a beginner to the Dumble scene, I'm looking at just taking the plunge and getting a ceriatone overtone 100 kit, including cabinet. I figure that will be the quickest way to get a taste of the ODS thing and then from there I could get into the building from scratch thing. Can anyone direct me to some good threads in this site about these kits, or offer any comment about these or other kits available.

With regard to PT's and OT's, I already have a set that I was hoping to use in the ceriatone kit. These were salvaged from an old Fender Silverface PA 100 amp head.

The OT is marked 'Fender 022889 -606-5-49'. Referring to pitmans tube amp book, the 022889 is the OT used in the silverface twin reverbs. It measures as follows:
Black to Green 0.375 Ohms
Blue to Brown 73.8 Ohms
Red to Blue 38.4 Ohms
Red to Brown 35.6 Ohms
I checked insulation resistance to 1000VDC and it didnt break down so the OT looks good.

The PT looks like it was a replacement made and fitted some time later. Its a lay down style PT (ie the windings come up through a big cutout in the chassis, like a twin reverb). Measures as follows:
Primary: Black to Black 240 VAC Input
Secondary 1: Green to Green: 6.9VAC out
Secondary 2: Red - White - Red: 342VAC - 0 - 342VAC
Bias Tap: White to Blue: 58VAC
I checked insulation resistance to 1000VDC and it didnt break down either.
It looks to be a direct replacement style PT for 100 watt silverface fenders. Weighs about 4.4 kilo (about 9.6 pound)

So does anyone know if these would be good candidates for the ceriatone kit and does anyone know if the ceriatone kit is designed for lay down style PT or upright style like a marshall?

Thanks for any advice,

Evan (ergotrons)

[bluesfendermanblues]

Hi Evan,
Sounds like a couple af nice trafos you got there. On Hammondmfg.com you can find more details if need be.

The Ceriatone is a fine kit. I've just build the 50w version with a couple of trafo's I had from old projects. And the chassis is made for the laydown type transformers.

You can find a all the info you need on ampgarage and a little bit on ceriatoneforum. But the latter is mostly concerned with questions regarding building assembling the kit.

I play mainly strats and teles , but also Les Paul and wanted a versatile amp, the will produce good tones with either type of instrument.
I discovered that the layout known as the #124 (with 100k/1.5k on V1) or the the ODS101 gave me the best OD and clean sound. This involves that you change 5-6 components after you have assembled and testet you ceraitone.

[ic-racer]

The OT is marked 'Fender 022889 -606-5-49'. Referring to pitmans tube amp book, the 022889 is the OT used in the silverface twin reverbs. It measures as follows:
Black to Green 0.375 Ohms
Blue to Brown 73.8 Ohms
Red to Blue 38.4 Ohms
Red to Brown 35.6 Ohms
I checked insulation resistance to 1000VDC and it didnt break down so the OT looks good.

I cannot comment on the power transformer, but the 022889 output transformer should be an excellent output transformer for a 100w non-HRM, like the Ceriatone.

[ergotrons]

Thanks for the responses guys. After doing a bit more reading I have one more question.
I see the ceriatone kit OT has taps for different impedance selections. This would obviously make the head more versatile for use with different speaker cabs/loads. My Fender OT can only match one load : 4ohms. So my question is: Is the fender OT that much better (tonewise) than the ceriatone supplied one that it is worth forgoing the extra flexibility of multiple impedance selections?
If it isnt that much better tonewise, I would probably consider selling my PT and OT on Ebay and just going for the complete ceriatone kit including his PT and OT to get the benefit of multiple impedance selection.

Thanks again for your input.

Evan.

[bluesfendermanblues]

I haven't tried Ceriatone's transformers, so I can't comment on the quality of these, but your fender transformers are more or less identical to the ones Dumble has used in his designs.

So I would keeps the ones you have.

An output transformer can always be 100% mismatched without any problems....this means your 4 ohm tap, will drive 2ohms and 8 ohms with no sweat at all.

[mojo]

I just got an Overtone in and tried to do the same thing. You save a significant amount in shipping by getting it sans transformers. Based on your description your transformers should work fairly well - I had to order a power transformer from Nik because mine didn't have a 60V tap to use. You also need a choke. I think the old Fender iron should be a slight upgrade, but I would find only having the 4 ohm tap somewhat limiting. If funds aren't an issue I'd suggest just ordering the whole enchilada from Nik. Its a somewhat complicated build - I found it much more cost and time effective to have Nik's team build the amp and I just added the transformers. I think as far as sound quality goes, the OPT is the one that might make a significant difference.

[bluesfendermanblues]

I just got an Overtone in and tried to do the same thing. You save a significant amount in shipping by getting it sans transformers. Based on your description your transformers should work fairly well - I had to order a power transformer from Nik because mine didn't have a 60V tap to use. You also need a choke. I think the old Fender iron should be a slight upgrade, but I would find only having the 4 ohm tap somewhat limiting. If funds aren't an issue I'd suggest just ordering the whole enchilada from Nik. Its a somewhat complicated build - I found it much more cost and time effective to have Nik's team build the amp and I just added the transformers. I think as far as sound quality goes, the OPT is the one that might make a significant difference.

You didn't need to order a transformer from Nik just to get 60vac. In fact you don't need a 60v tap at all - just connect to one of the red 360vac taps through a 150k reisitor and you will be fine.

[ergotrons]

Thanks again for the feedback guys. I'll see if I can contact Nik and get some confirmation on the mounting dimensions for the trannys on his chassis and maybe go with my set if it looks like they'll fit straight in.

Cheers