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31  Ceriatone / Overtone / Re: Trouble setting PI balance at 6VDC on: May 06, 2011, 09:42:51 PM
i should probably restate what i said Smiley

i think it's more in my head than anything Wink not so much that it sounded bad, just wasn't getting quite what i wanted out of it. sounded good, but not great, and indeed when i put the meter on the pi trimmer circuit it was perfectly balanced, ie no voltage difference V3a and V3b at all, so the "balanced" triodes were doing what they were designed to do, and the amp sounded great and, well, balanced, for lack of a better term, but didn't quite get the bloom as i was after. after i made the adjustment though, i got that elusive bloom and all is well.
i think it had more to do with the tube that anything, not that it was bad, just that it is a lower gain tube and set up to be balanced and needed a little help getting that voltage swing. Long story short, making that adjustment made a great amp sound even greater Smiley

Plastic, are you measuring DC or AC on the PI tube .

You should adjust the trimmer with a tonegenerator connected, measuring AC and trimming until you get an equal amount of AC on each side with reference to ground. Forget the DC difference between the two halves, it will be different from tube to tube. A balanced tube will put close to equal amount of AC from each triode.
32  Ceriatone / Overtone / Re: Trouble setting PI balance at 6VDC on: May 06, 2011, 09:08:41 PM
I was about to sell my Strat because it sounded like crap through the BM (awesome amps can show either how good or bad your guitar is), but after tweaking the PI trimer, i have fallen in love with my strat again, and all my other axes sound even better now.
Gregg

I use a LPS sovtek PI and finding the sweet spot on the PI trimmer - never changed my amp to the degree you describe, up to the point where your guitar sounds bad.  Huh? Huh?

IMO You must have had a bad tube in there in the first place.

IME The PI trim has an important but minor impact on the tone.
33  Ceriatone / Overtone / Re: Overtone fault can anyone help? on: May 02, 2011, 12:42:14 PM
Hi,

I have just completed my overtone build, but I have a fault on the overdrive channel.

When I switch to the overdrive channel, only the pre amp section is working so I  have very little volume compared with the clean channel which is working fine with plenty of volume.

Can anyone help? I would be very grateful for any advise

Thanks

God news - if you can build an Overtone and get sound with the clean channel, you should be able to fix the issue as well. :-)


First check the OD relay wiring

If relay is wired correctly, check wiring of OD tube socket and wiring of OD pots.

Do you heating wire on V2 (does it glow)

Have you checked the voltages on V1 and V2

good luck
34  Ceriatone / Overtone / Re: Amp Mods on: April 24, 2011, 10:53:44 PM
Hi Beanbag, welcome to the forum and great report on your amp.

I guess we all experienced the same as you have -  a new dumble clone amp sound very harsh and unforgiving.

Nice mods the 82k slope and 750pf on V2a.... I'll bet in two month you won't need the 750pf on v2a, in fact I have just removed the additional 220pf on my #183, leving me with 22pf on both v2a and v2b and no the OD top is much more open. However, like you , when the amp was new it had much to much OD top.

I have 20 years experience with DIY tube amps and repairs and untill 2 years ago I wouldnt have believed in the fact that these amps need burn in time.
35  Ceriatone / Overtone / Re: Speaker Choice for 100w Bluesmaster cab on: April 21, 2011, 08:27:03 PM
Not really The answer you asked for, but if dont need 100w why not pull out 2 output tubes and put The impedance selector to 4 ohm and you Can use a single 12g65.
36  Ceriatone / Overtone / Re: Thicker Sound on S&M on: April 08, 2011, 01:59:25 PM
Hi Bluesfenderman
Cheers I'm gonna have a 3 way switch put on the V2b snubber to try a few values there Smiley...........theres no deadly voltages on that one is there!? Shocked .....Does anybody have a schematic?

The voltage on V2b is around 200V and Lethal - BE CAREFULL !!

You can use pickmaster's schemo: http://ceriatoneforum.com/index.php?topic=740.0
37  Ceriatone / Overtone / Re: Trouble setting PI balance at 6VDC on: April 07, 2011, 10:03:23 PM
Wilcox and Mojo,

Great you found the sweet spot on your PI's - now lets play!!
38  Ceriatone / Overtone / Re: Trouble setting PI balance at 6VDC on: April 06, 2011, 04:53:16 AM
.... read that the HRM circuit isn't as quick to do this. Is this correct?

Thats right, at least thats my experience. Think it's due to the fact that the HRM and BM has a little less midrange than the Standard (RF) amp.

However, the HRM's (Bluesmaster and HRM) seem to blend in more easily. I usually bring my Bluesmaster to rehersals or gigs, but love to play the standard amps at home with feedback and all. Te Standard amps are more of a soloist amp - think RF or Santana.

Using a Dumbleator relly helps the amps to breath and feedback at low volumes, because you run the master(s) around noon and adjust master level on the Dumbleator.

...noticed the more I play it the more it seems to be relaxing and getting closer to the tone of some of the killer clips I hear.

Yep, this is a fact. A new amp sounds harsh, but after a couple of months of exercise, it mellows and opens up nicely.
39  Ceriatone / Overtone / Re: Trouble setting PI balance at 6VDC on: April 05, 2011, 09:43:57 PM
Remove the dummy load and connect your guitar. Turn up the amp volume and presence pot, carefully rub the strings with your palm and slowly try adjusting the trim around the point you marked, listening for max amount of harmonics.
Hey blues, do you use the clean channel or OD channel when rubbing the strings? I guess my question is...overall is there settings aside from presence (ie: gain levels, rock/jazz switch, etc.) that makes it easier to hear the "sweet spot"? I used the OD channel when adjusting, but didn't know for sure what was best.

I'm not an expert on the subject, but I guess you can use both. I you use the clean channel, listen for sparkle in open G chord. If you use the OD listen for the OD overtones or even feedback.....the point where you can feedback easily is THE point.

Many people try to turn this subject into a Dumble voodoo for the selected few. IMO it's not that hard to adjust. It takes max 5 min. after the get the chassis out of the head cab.
40  Ceriatone / Overtone / Re: Trouble setting PI balance at 6VDC on: April 05, 2011, 06:12:28 AM
You can adjust the PI trimmer without a scope.

Inject a sine wave signal ~ 400Hz -1000Hz at the amp input (or at power amp input, labeled 'return') and measure the AC voltage at the power tube grids. I set it about 20-30 v AC -between the grids - and use the trim to set each grid the same -measured from grid to ground. Don't forget the dummy load on the speaker out. I use a 10 watt 8 ohm resistor. It gets a little hot, but thats not an issue since the whole procedure takes about 2-5minutes.

This gives you the correct balance, with max signal possible out off the PI. And it'll look great on the scope.

Mark the trimmer position with a pen.

Remove the dummy load and connect your guitar. Turn up the amp volume and presence pot, carefully rub the strings with your palm and slowly try adjusting the trim around the point you marked, listening for max amount of harmonics.
41  Ceriatone / Overtone / Re: Effect of Negative Feedback on: April 05, 2011, 06:02:20 AM
I'm a newcomer to the "Dumble Way" and probably have about 25 hrs play time on my amp. (HRM 50) I decided tonight to play with the LNFB switch ON and try to get a real grip on this. Like Todd mentioned it's mostly subtle, but like everything else I'm finding out about this amp, all or most of the different switches and settings can have a big effect on another.

One thing I found is that the volume drop going from rock to jazz in clean mode is not there with LNFB switched on. And it opens up the low end really well. In fact a new favorite setting is the clean channel set to jazz with deep on and LNFB. With single coils mostly.

I'm really starting to see the genius of HAD's design. There are really very many voicings available. The way some of the tone switches interact with others is pretty awesome. I've had amps with lots of switches (Mesa Rectifier) but in the end it never really changed much from the overall sound. Not so with these amps.

The only problem I see, is not being able to get to some of the tweaking possibilities quickly. But then again there comes a time when I need to play the darn song and forget about obsessively messing with the amp.  Grin

Fully in agreement with you regarding Dumble style amps. They are designed for studio and stage playing and sound ine at bedroom level, but even better at higher levels.

Before I build my Dumble clones, I spend a lot of time playing Mesa Boogie amps and IMO they are really great amps. If you can't afford, find or build a Dumble clone buy a Mesa.
42  Ceriatone / Overtone / Re: Thicker Sound on S&M on: April 04, 2011, 07:35:42 PM
Hi JD0x0
I guess the clean really. I like the character of the overdrive. Am I right in thinking that whatever I do to the clean will affect the overdrive anyway?

Hi Tone Control
I'm using a 77es335td with the original pickups. It's the model with coil tap, so I can get a single coil vibe. I use a clator, and an eventide H3000. As for the way I use the amp controls, it really varies a lot. I've been trying it at different settings to see what it can do.

I haven't tried that model OTS. I saw a previous post that said they could not find a setting on it that worked when switched from clean to OD: each needed a diff EQ setting, and the OD was harsh. Can you get a good clean sound at all? If you are dialling out the harsh OD, that would mess up your clean. That's why I like the HRM BM

Having said that, I could get a sound working from my Fuchs ODS (non-HRM) and my standard OTS, but D-styles take some work to get your settings.
for me, on the non-HRM ones, I dial the left OD pot down, but that's just me. You have 4 or 5 pots to play with after all, before the EQ, so it needs some serious experimenting.

Does the PAB sound nasal, or the OD?


Just up the second snubber cap to taste - maybe from 270p to 500p or 800pf - no rules, just do what sounds best....
43  Ceriatone / Overtone / Re: Overtone Special. A SNAKE IN THE GRASS on: March 27, 2011, 08:55:46 AM
I find that with the OTS the sparkling highs disappear when I use the loop but truly a great amp.   

Which is why you may have to add a 47p-68p (I have 100p om my Bluesmaster, clean master) in order to get enough high end with a dumblelator. However, your tone will be rewarded with nice 3D quality and a bit of compression.  Cool
44  Ceriatone / Overtone / Re: Anyone tried Boss TU-2 as splitter for dual amp set-up? on: March 25, 2011, 01:05:00 PM
you don’t need lousy C-lator

WHAT??? lousy?? no no it's a necessity    Wink

I respectfully disagree  Cool
45  Ceriatone / Overtone / Re: Indicator light blown? on: March 25, 2011, 06:34:17 AM
Sorry but for a complete novice (me) how are the 3 components connected together to get the LED operating properly?

No problem, check the bottom of the schematic in this link:

http://ampgarage.com/forum/download.php?id=14563
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