Ceriatone Plexi filtering

[dstroud]

looking to pull the trigger on a ceriatone 1987. nik said he prefers the ‘70 style with heavy filtering. How much difference does the filtering really make towards the tone? anyone care to share experiences? I think the one I have is a 68 style with soft filtering. Is it more a feel than tone?

 

[harddriver]

32uf filtering mains, screens and PI can lead to ghost notes. 100uf on the PI tends to help clear up ghosting. I have 68 metro plexi with the low 68 filtering on the mains, screens but I ran 100uf on the PI. I also built a 69 SL with 50uf on the mains. screens and 100uf PI all the cap cans were new production ARS 50uf/50uf. The 100uf on the PI give it a little more backbone on the lows but it still had a great plexi feel and tone. I would venture to say that since the 69 would sound great without variacing and such and it still gave up the goods like my 68 says alot. I guess the lower filtering kind of gives a slightly softer feel but not by much, At times my 68 maybe has a tiny bit of ghosting with certain tubes but I m running Sylvania preamp tubes and Sylvania 6ca7's in the clips. The 69 had no ghosting and I was running Modern Tung Sol V1, Ruby HG5 Chinese V2, Sylvania V3 and EH 6ca7 power tubes. You could start low and try it then go higher to compare. I've heard alot of 69 Super leads that rival any 68 with the lower filtering.

Opps... I forgot to tell you what the preamp filtering was, on the 68 I am running 32uf/32uf NOS Eire axial cap for each half of the preamp circuit. On the 69 I am running an new ARS 50/50uf upright can cap for each half of the preamp circuit. I think some of the early 67 12000 series amps ran 16/16uf on the preamps but I really feel that is way too low but some on Metro experimented with it and I think most ended up at 32uf to 50uf because of ghosting.

Here's the 69 with the higher filtering,no varic no reamping.


Here's the 68 for comparison, it's variaced and reamped through a 72SL

 

[napalmdeath]

'69 sounds tits!

 

[dstroud]

right on Harddriver!! that is exactly how I run my current 1987, master on 5 and Boss sd-1. I just opened mine up to see what the filtering is and looks like 50+50 and 47+47, so Ill stick with that

 

[fusedbrain]

So I think you need to make the distinction between the filtering setup for the 50 watt vs 100 watt amps.
On the 100 watt amps, you can control the values for the mains, screens, and PI individually.
On the 50 watt amps, there are only 3 cap cans.
Typically, that means the mains filter cap can has the 2 halves in parallel ( adding the values together ) , the screens and PI sharing a cap can, and the cap can for the 2 nodes on the pre amp.
In this scenario, I like to run a 50 x 50 ( 100uf ) on the mains, 16 x 16uf for the screens and PI, and 32 x 32uf in the pre amp.
The 100uf on the mains is why the 50 watt amps are so spanky. Keeps thing tight and keeps the B+ clean.
The 16uf on the screens and PI gives you back a bit of that greasy feel.

You can also wire it up with the mains and screens sharing a cap can, and have the PI run 50uf x 50uf in parallel, but then you have to choose 50uf or 32uf for mains and screens to share. 50uf on the screens in really stiff, and 32uf on the mains is a little soft and can lead to ghosting.

You will probably just have to try a few different setups and see what you like.
Only definitive thing I can say is the "feel" is on the screens.

 

[odgeuk]

So I think you need to make the distinction between the filtering setup for the 50 watt vs 100 watt amps.
On the 100 watt amps, you can control the values for the mains, screens, and PI individually.
On the 50 watt amps, there are only 3 cap cans.
Typically, that means the mains filter cap can has the 2 halves in parallel ( adding the values together ) , the screens and PI sharing a cap can, and the cap can for the 2 nodes on the pre amp.
In this scenario, I like to run a 50 x 50 ( 100uf ) on the mains, 16 x 16uf for the screens and PI, and 32 x 32uf in the pre amp.
The 100uf on the mains is why the 50 watt amps are so spanky. Keeps thing tight and keeps the B+ clean.
The 16uf on the screens and PI gives you back a bit of that greasy feel.

You can also wire it up with the mains and screens sharing a cap can, and have the PI run 50uf x 50uf in parallel, but then you have to choose 50uf or 32uf for mains and screens to share. 50uf on the screens in really stiff, and 32uf on the mains is a little soft and can lead to ghosting.

You will probably just have to try a few different setups and see what you like.
Only definitive thing I can say is the "feel" is on the screens.

This was a really helpful explanation of filtering in these circuits for me. Thanks. It's cleared a few things up. Can I ask though, which cans are which? In a 50w? The two next to each other by the Mains input I'm thinking are the Mains and Screens/PI? And the other cap that sits above the circuit board is the Preamp?

To achieve the 50w lower filtering you'd need to have three filter caps: 100uf mains (in parallel for 50uf), 16uf (in series for Screens/PI) and a 32uf (in series for the preamp)?