Ceriatone RockIt OT issue

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HotWire
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Ceriatone RockIt OT issue

Post by HotWire »

Hi Everybody ! I'm more of a reader than a poster, but I have a question or two.

I built a Wreck RockIt kit using a genuine A-470 Dynaco OT and I'm not sure what leads to use. They are the cloth leads and are tough to differentiate, but I have:
blu/white 101 ohm to CT
Grn/ wht 33 ohm
Red Center
Green 29 ohm
Blue 89 Ohm

I'm currently using Blu/white and Blue (199 ohm end-end)


EL84 voltages:
2 control 0V
3 Cathode Supressor 31V
4 Heat 3.3V
5 Heat 3.3V
7 Plate 354V
9 Screen 351V

I get no sound whatsoever. Any ideas are greatly appreciated.
HotWire
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Joined: Wed Apr 14, 2010 3:32 am

i guess like this?

Post by HotWire »

HotWire
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Re: Ceriatone RockIt OT issue

Post by HotWire »

rock_mumbles
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Re: Ceriatone RockIt OT issue

Post by rock_mumbles »

Your voltages are really high for a rocket ...

You should have the screen taps, green leads on the OT insulated
HotWire
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Re: Ceriatone RockIt OT issue

Post by HotWire »

rock_mumbles wrote:Your voltages are really high for a rocket ...

You should have the screen taps, green leads on the OT insulated
I know. El 84 doesn't like it above 300V. I have the unused green leads taped-off.
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M Fowler
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Re: Ceriatone RockIt OT issue

Post by M Fowler »

Don't know what PT your using or secondary HT voltage used. For Rocket anything from 240-0-240 to 280-0-280 is fine.

Don't do like I sometimes do using 300-0-300 it can eat tubes fast :)
I'm currently using Blu/white and Blue (199 ohm end-end)
Yes this is correct.
HotWire
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* Solved *

Post by HotWire »

So I left the amp alone for awhile- came back and looked at it at about 4:30 am- saw a connection I missed on the half-power switch connecting center 2 poles.

Bam. Fixed. el84 Voltages 291

So, it's a quarter to 5 in the morning- do I take it for a test-spin or do I let everyone in the house sleep :)

I let them sleep. Amp sounds great- very happy so far using w/ my test 10" weber.
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johnnyreece
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Re: Ceriatone RockIt OT issue

Post by johnnyreece »

Congrats! Glad it was an easy fix!
tsutt
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Re: Ceriatone RockIt OT issue

Post by tsutt »

So what is the best voltage to run el 84 at. i see them all over the place. My spit clone variant uses a marshall 18 classic tone pt 290-0-290. i have 364 on the plates. I have read up to 400 on the plates is ok, so whats the deal?
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M Fowler
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Re: Ceriatone RockIt OT issue

Post by M Fowler »

tsutt wrote:So what is the best voltage to run el 84 at. i see them all over the place. My spit clone variant uses a marshall 18 classic tone pt 290-0-290. i have 364 on the plates. I have read up to 400 on the plates is ok, so whats the deal?
Tube quality is the problem for higher plate and screen voltages.
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Blackburn
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Re: Ceriatone RockIt OT issue

Post by Blackburn »

My vote is keeping the plates as close to 300 as possible will yield the most desirable results. This is pretty hard to do these days, as most builders are using PTs that are just too hot. I have built a couple Dominator style amps and they're running around 330 and not bad, but I prefer what's on the spec sheet. Those amps aren't too good with the cleans, but get real brown dimed because of the circuit.
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johnnyreece
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Re: Ceriatone RockIt OT issue

Post by johnnyreece »

The Crate VC 50 I gutted ran them at 391. I bought the amp from my cousin, who said he only retubed it once (and this was an amp from the '90s). I was surprised.
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Blackburn
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Re: Ceriatone RockIt OT issue

Post by Blackburn »

Yeah, a lot of the newer tubes can surprise you with what they can put up with. I personally don't think it matters because the tone of the newer ones is nothing special at any voltage or dissipation. More so for the mass produced stuff.
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