Welcome, Guest. Please login or register.
Did you miss your activation email?
March 29, 2024, 02:08:27 AM
Home Help Search Login Register
News: Ceriatone Forums are up and running!!!
 
Guests please register
Note: If you want to help you can donate to keep the forums alive.



Do you want to advertise on this forum ? Send me a private message.



Amplified Parts
+  Ceriatone Forum
|-+  Ceriatone
| |-+  Overtone
| | |-+  Amp Mods
« previous next »
Pages: 1 [2] 3 Go Down Print
Poll
Question: OTS - modifications  or not?
Not modded   -10 (43.5%)
Modded   -13 (56.5%)
Total Voters: 23

Author Topic: Amp Mods  (Read 23379 times)
bluesfendermanblues
Sr. Member
****
Offline Offline

Gender: Male
Posts: 452



View Profile
« Reply #15 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.
Logged

Respect for the big guy's work....we're at this part of the forum because of HAD's amps.
dannysgrandpa
Jr. Member
**
Offline Offline

Gender: Male
Posts: 64


Life is good here! God is good...all the time!


View Profile WWW
« Reply #16 on: May 12, 2011, 05:06:26 AM »

I have an '08 OTS 50 and the only mods I've done are: removed the FET input, (didn't use it), and put a "deep" switch
in it's place, put the OD trim pot on the back panel, and put a 15pf bright cap on the master volume pot. I LOVE THIS AMP!!!!!  Built a D-style cab with an EVM-12L and I can get just about any tone I want from Carlton, Ford, SVR and even Bonnie Rait's slide tones. Yeah, these amps are amazing for slide, clean or overdriven! 
Logged

Make a joyful noise...that is smooth, tight and punchy! I believe that God likes tube tone.
Certified IPC Master Trainer: 610G, 620C, J-STD-001G/Space, 7711C/7721C. Hands on soldering trainer, inspection trainer and Electrostatic Discharge instructor.
Steven_nl
Sr. Member
****
Offline Offline

Gender: Male
Posts: 473



View Profile WWW
« Reply #17 on: May 16, 2011, 08:15:21 AM »

I have got an OTS as well Plus a D'lator (made by Erwin)
I experimented with tubes a lot but still found the OTS a bit to  much "in your face" Erwin now changed the amp and made it into a combination between a Bluesmaster (cleans) and an OTS (lead). He also added a 0,47pf cap on the (push pull) master volume.
Great mod.
Logged
babybear2011
Newbie
*
Offline Offline

Posts: 25


View Profile
« Reply #18 on: May 18, 2011, 11:47:00 AM »

How did he change the OTS cleans to Bluesmaster spec then?? My OTS's clean channel sucks ass. Apparently the Dumble is supposed to be a modified Fender Twin, my clean channel certainly doesn't sound Fendery at all. Zero headroom and sounds spanky than the chimey cleans Fender are renowned for. I use a strat through my OTS and the OD channel is a bit too fizzy and no bottom end at all, but when the PAB is engaged, it sounds much better, more open and harmonic. Maybe has something to do with the V30 I'm using instead of a EVM12 or G12-65??
Logged
axiology
Newbie
*
Offline Offline

Posts: 27


View Profile
« Reply #19 on: May 18, 2011, 02:24:55 PM »

How did he change the OTS cleans to Bluesmaster spec then?? My OTS's clean channel sucks ass. Apparently the Dumble is supposed to be a modified Fender Twin, my clean channel certainly doesn't sound Fendery at all. Zero headroom and sounds spanky than the chimey cleans Fender are renowned for. I use a strat through my OTS and the OD channel is a bit too fizzy and no bottom end at all, but when the PAB is engaged, it sounds much better, more open and harmonic. Maybe has something to do with the V30 I'm using instead of a EVM12 or G12-65??


There's got to be something wrong with your amp, either construction error, faulty component or improperly adjusted bias. Not something some mods are going to fix. Did you make it yourself?
Logged
SoundPerf
Sr. Member
****
Offline Offline

Gender: Male
Posts: 392



View Profile
« Reply #20 on: May 18, 2011, 05:37:20 PM »

How did he change the OTS cleans to Bluesmaster spec then?? My OTS's clean channel sucks ass. Apparently the Dumble is supposed to be a modified Fender Twin, my clean channel certainly doesn't sound Fendery at all. Zero headroom and sounds spanky than the chimey cleans Fender are renowned for. I use a strat through my OTS and the OD channel is a bit too fizzy and no bottom end at all, but when the PAB is engaged, it sounds much better, more open and harmonic. Maybe has something to do with the V30 I'm using instead of a EVM12 or G12-65??


There's got to be something wrong with your amp, either construction error, faulty component or improperly adjusted bias. Not something some mods are going to fix. Did you make it yourself?
I would have to agree with axiology on this one. It really sounds like there maybe something wrong. The V30 isn't the best speaker for the OTS, but I played through one for a bit and it wasn't that bad. What tubes and settings do you use? Where is the O/D trim set?

Edit: I just saw that I spelled forum member "axiology" incorrectly and could have been taken the wrong way. Complete accident....sorry.  Embarrassed
« Last Edit: May 19, 2011, 01:06:53 AM by SoundPerf » Logged

Chris

Ceriatone HRM 50
w/self built Dumblelator
Avatar 2X12 w/WGS ET-65 & Veteran 30
TC Electronic 2290
2001 PRS McCarty
2010 PRS 513 Swamp Ash
Tacoma JK50C
Seagull S12+
Steven_nl
Sr. Member
****
Offline Offline

Gender: Male
Posts: 473



View Profile WWW
« Reply #21 on: May 19, 2011, 08:30:49 AM »

How did he change the OTS cleans to Bluesmaster spec then?? My OTS's clean channel sucks ass. Apparently the Dumble is supposed to be a modified Fender Twin, my clean channel certainly doesn't sound Fendery at all. Zero headroom and sounds spanky than the chimey cleans Fender are renowned for. I use a strat through my OTS and the OD channel is a bit too fizzy and no bottom end at all, but when the PAB is engaged, it sounds much better, more open and harmonic. Maybe has something to do with the V30 I'm using instead of a EVM12 or G12-65??

I have no idea what he did to my amp. I can't even solder a guitar cable. Perhaps you could pm him (Erwin_ve).
Logged
babybear2011
Newbie
*
Offline Offline

Posts: 25


View Profile
« Reply #22 on: May 19, 2011, 01:37:52 PM »

I didn't build the amp myself. I bought it from a well respected amp builder, but maybe he can fuck up sometimes I guess. I haven't adjusted the bias or the internal OD trimmer. To be honest I'm not sure how to tweak an amp like this. As in, how much is too much? Will I damage the amp by this. Is there a setting on the bias/OD trimmer I could set it to sound great without messing with it. I do have an ear for tone, but I'm also prone to breaking amps by fucking about with them too. I was told on here to set the bias to 35-40mv, the same as milliamps because of the 1ohm resistor that's supposedly installed on the circuit.
Logged
babybear2011
Newbie
*
Offline Offline

Posts: 25


View Profile
« Reply #23 on: May 19, 2011, 06:43:46 PM »

I just tried biasing the OTS via black to earth point and red probes into the test points either side of the power tubes, flicking the amp on to Operate and switching the digi MM on. The readings kind of baffled me somewhat. The reading on one side was 150.6mv and the other was 170.6mv, surely I must be reading this wrong, but it's a simple thing to do. I also turned the dial to one end to the other and not much of a difference in readings. Maybe 20mv difference. Please help on this cos I seem to be doing something totally wrong.
Logged
SoundPerf
Sr. Member
****
Offline Offline

Gender: Male
Posts: 392



View Profile
« Reply #24 on: May 19, 2011, 07:41:58 PM »

I just tried biasing the OTS via black to earth point and red probes into the test points either side of the power tubes, flicking the amp on to Operate and switching the digi MM on. The readings kind of baffled me somewhat. The reading on one side was 150.6mv and the other was 170.6mv, surely I must be reading this wrong, but it's a simple thing to do. I also turned the dial to one end to the other and not much of a difference in readings. Maybe 20mv difference. Please help on this cos I seem to be doing something totally wrong.
Did you replace the HT fuse? First, are you getting any sound from the amp. Position the bias pot to it's halfway point and try the amp. If no sound, then there's a greater problem then bias. To answer your question, Yes there's somehting not correct in you bias measurements. When you say "earth point" are you placing the probe in the black test point between the two red ones?
Logged

Chris

Ceriatone HRM 50
w/self built Dumblelator
Avatar 2X12 w/WGS ET-65 & Veteran 30
TC Electronic 2290
2001 PRS McCarty
2010 PRS 513 Swamp Ash
Tacoma JK50C
Seagull S12+
babybear2011
Newbie
*
Offline Offline

Posts: 25


View Profile
« Reply #25 on: May 20, 2011, 12:12:55 PM »

Yes, the amp is fully operational. I replaced the HT fuse which cured the problem of no sound. Now the amp is back like it used to be - loud and proud. I put the black probe into the black test point in between the two power tubes, then the red probe into the red test point of each tube left and right. I switch on the multimeter on to read 'mv' and begin testing.....then the readings baffled me.....don't know what else to do!! I don't want to blow the amp again. If anything, I'd rather run the amp 'cold' to prolong tube life, I just don't know which way to turn the dial, it's either 'blow' the amp again or 'cold'. But I'm not taking a chance in guessing! Please help.
Logged
playindabluz
Newbie
*
Offline Offline

Posts: 2


View Profile
« Reply #26 on: May 20, 2011, 02:24:41 PM »

I have an OTS 50w. Can't quite seem to find the tone I'm lookin for. Recently modded to FM 50.  I am liking the tone of the 183 much better.  How close to the 183 can I get without adding all those filter caps? Any suggestions please?
Logged
plasticvonaband
Hero Member
*****
Offline Offline

Gender: Male
Posts: 747


Pickin and Grinnin since 1989


View Profile WWW
« Reply #27 on: May 20, 2011, 06:42:56 PM »

@ babybear, it sounds like you are reading both tubes at once, or possibly reading ac current, which is possible if you are reading both tubes via the reds. you will want to insert a red probe in one red socket at a time, and the black probe in the center black socket. Also you will want to make sure that all front controls are set to zero and that you have a speaker or dummy load plugged in. You will want to set your multimeter to the mV or smallest scale on the DC side. You will want to adjust your current to somewhere between 35-40 mV as a starting point. You can adjust up or down to taste, with 47-48 mV (mA in reality) being the upper safe limit for most 6L6 tubes.
« Last Edit: May 20, 2011, 07:45:45 PM by plasticvonaband » Logged

Overdrive is like peanut butter. Some like it crunchy, some like it creamy.
Bluesmaster 50 2x12 combo and some guitars.
babybear2011
Newbie
*
Offline Offline

Posts: 25


View Profile
« Reply #28 on: May 21, 2011, 07:35:56 AM »

@plasticvonaband, I didn't plug to red probes in. I did one at a time, one red probe, one black probe. I left the black probe in the black test point at all times, then switched between the two red probes, back and fore to test the bias. It does sound like two power tubes are being tested together, but surely turning the bias pot up and down would change the readings, but it didnt. I set the multimeter to mV as required. Left the speaker in cos it's already in a combo build, all dials were zero. Is there something I'm missing? I'll try and take a photo to see if anyone could help.
Logged
sduck
Full Member
***
Offline Offline

Gender: Male
Posts: 173



View Profile
« Reply #29 on: May 22, 2011, 03:13:41 AM »

If you're getting 170 mv you're basically destroying those tubes. You'll need to check the wiring around the power tubes and/or the transformer extra carefully, find what you've done wrong and fix it. Then most likely replace the power tubes. It probably needs to go to a tech for this.
« Last Edit: May 22, 2011, 03:16:13 AM by sduck » Logged
Pages: 1 [2] 3 Go Up Print 
« previous next »
Jump to:  


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.12 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!

CeriaTone Forum is not afiliated with Ceriatone Amplifications. The CeriaTone and name, logo and related trademarks and service marks, owned by CeriaTone. , are registered and/or used in the U.S. and many foreign countries. All other trademarks, service marks, and trade names referenced in this site are the property of their respective owners.