Ceriatone Forum

Any suggestions for the V3,what are the effects?

if youre talking about the V3 tube go with a long plate with balanced triodes.

I like the JJ803s as it gives a nice bit of lower mids and sounds very smooth.

I dislike JJ's in V1 and V2 though

I prefer JJ's in V1 and V2 positions. It a must use for Robben Ford tones.

i dont try to emulate other player's tones, but to me the JJ's seem kind of "dry" or something. they just dont do it for my ear. I have an old RCA in V2 and a tungsol RI in V1. When the RCA dies it's going to get replaced by a Mullard RI. I dont ever buy NOS tubes i found the RCA thats why it's getting used.

I had JJs in my HRM and decided to try some old RCA back plates (one long and one short) in V1 and V2. But they seemed to smooth (especially the long plate).

However I did like (decided to go with) the short plate in V1 and the JJs in V2 and the PI.

although not quite what you need:
http://ceriatoneforum.com/index.php?topic=628.0

but this is:
http://ceriatoneforum.com/index.php?topic=956.0

Interesting comments.

I added several mods to my HRM so it's also not stock: increased V1a and V1B cathode bypass caps to 10 and the V2a cap to 5; increased v2a to v2b coupling cap to .01; increased V1a .002 coupling to .004; lowered the v1a plate resistor to 100; removed the master vol bypass cap; removed the 47p/470r network at the OD entrance; lifted the 10K from the Bass control; and added an external pot for the PI trim.

I'll have to try changing the PI tube to a T or Y to see the effect.

What effect will that have?

Oh, I meant to type 100K (not 100) and of course I also changed the cathode resistor to compliment.
100k/1.5k.

The standard plate cathode resistor scaling is:
100k/1k5 - 120k/1k8 - 150k/2k2 - 180k/2k7 - 220k/3k3

A lower plate resistor is supposed to make the clean stage clearer and less compressed. But it might also sound thinner unless the cap from cathode to ground is at least 10uf or even 25uf and not the 5uf that it usually is with a higher plate resistor.

Fender amps typically use 100K plate resistors.

But then don't you know this?

Still learning.....  :)

Tell me...
I'm still wondering if a different tranny would help much towards getting a smoother sound.
Oh, I also lowered the .05 cap from V1 to V2 to a .02.

i changed to a fender choke and it seemed to help the sound. i havent tried different PT and OT though.
Also just an FYI i wouldnt bother spending the $300 or however much the MM power tranny is just because the actual PT doesnt have any effect on the sound. (mercury magnetics will try to convince you otherwise for obvious reasons. $$$) the voltages do matter though. And different voltages doesnt garentee better tone. It could easily ruin the tone. A different OT will definatly change the sound though weather it's better or worse is totally up to your ears.

It's too bad there aren't really any sound clips comparing transformers on a overtone, being it's an major expense and not the kind of thing that easily swaps in and out.

However, I think I'm pretty satisfied with the amp's sound. I only just finalized my mod today. I wanted to be able to get a mellow horn like OD, and pretty much ended up with an OTS but with a few differences.

In sequential order around the circuit they are:
1) V1a plate/cathode changed to 120k/1.8k;
2) V1 cathode caps changed to 10uf;
3) Bass control 10k resistor to ground removed;
4) V1b to master volume coupling cap reduced to .02 (from .05);
5) Master volume 47pf bypass cap removed;
6) Switch added to 47pf cap across 470K resistor at OD stage entrance;
7) Three way switch adding .0062 cap; .0022 cap; or no cap; to ground before 470K resistor at OD stage entrance; (treble bleed);
8) V2a to V2b coupling cap increased to .01 (from .002);
9) V2 cathode caps changed to 15uf
10) External PI trimmer pot;
11) Short black plate RCA at V1; JJ at V2 and PI.

tonally what did removing the 10K resistor on the bass pot do?

I didn't notice much difference in how my tone controls operated with the 10k detached, which is not quite what I would expect.

However, I removed it in effort to get less volume difference between the normal and PAB volume. It seems that the tone stack clamps the sound and volume and that all the PAB does is free it from clamping. So I think the difference, if any, is that the normal sound is a tiny bit more free sounding.

I was mostly trying to get an OD sound that I liked. As I recall the change from lifting the 10K was more noticeable when using the OD than clean.

I've read people complain that activating their OD stage made their sound darker. In the HRM, I found the OD to be too hard and shrill. That is why I increased the interstage coupling cap from .002 to .01 (to be the same as the OTS) and added a treble bleed in front of the OD stage. In listening tests, to me, removing treble at the end of the stage (like the HRM stone stack affords) does not sound any where near as good.

thanks :)

i have to agree the tonestack does "clamp" the sound as all tonestacks do since they reduce gain.

Im building an ODS (not ceriatone though i do have a non-HRM OTS and love it) and i think i have solved the PAB volume difference by making the tone stack more efficient so it doesnt take away as much gain. so you dont actually have to make the PAB volume lower because the volume between the two are closer.

the tonestack should only lose about 3dB of gain with my design. so the PAB should add about the same back when it's engaged

Sounds interesting. I never experimented to determine just how much a standard stack clamps the signal.

I assume the degradation is due to the load of the ground path hanging on the tube's output. Is there no way or easy way (using tubes) to capacitively separate the treble, mid, and bass and then sum them without using a ground path to reduce their level.

However, sometimes people want the lesser or particular tone that comes from a stack. I believe, for example, the stack design accounts for the difference between a Tweed and Blackface tone - with the 60's having a stronger scoop in the low end so that it sounded cleaner.

Without the stack, the sound is much more robust, which may not be desirable as the only tone.

So maybe the optimal thing to provide the ability to switch between two levels of the stack sound in addition to the direct sound - all of which could be adjusted  by a simple gain pot. That would simply require reducing the gain of the stack for use as the normal sound, and simply eliminating the gain reduction for the relative boost. Then there can also be the option of the sound with the stack bypassed, with a level control.