ODS in Progress
Moderators: pompeiisneaks, Colossal
Re: ODS in Progress
Not sure if this will help you or confuse you but this is the way my D'Lite is wired.
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Tom
Don't let that smoke out!
Don't let that smoke out!
Re: ODS in Progress
Thanks that helped. After looking at that layout and the Ceriatone layout I am confused about the 124 layout/schem.
The PAB DPDT at the back wont work. No relay clicking, the coil is not being energized.
I think it is missing a ground connection. There is no way to ground the diode's anode without using the footswitch. I am going to add the ground connection to the unused pole and report back.
EDIT: Yet I look at the 124 schem, layout and pics and all three show the unused pole not having a ground connection. Obviously the amp worked so I am wondering...
The PAB DPDT at the back wont work. No relay clicking, the coil is not being energized.
I think it is missing a ground connection. There is no way to ground the diode's anode without using the footswitch. I am going to add the ground connection to the unused pole and report back.
EDIT: Yet I look at the 124 schem, layout and pics and all three show the unused pole not having a ground connection. Obviously the amp worked so I am wondering...
Re: ODS in Progress
Adding the ground wire made the PAB switch work.
Whats the point of the 100nF caps?
Whats the point of the 100nF caps?
Re: ODS in Progress
I assume that's minimize popping when the relays are energized. Never used them myself.ChrisM wrote:Adding the ground wire made the PAB switch work.
Whats the point of the 100nF caps?
Glad you got the PAB relay firing. I've never understood why that switch was ungrounded in 124.
"Let's face it, the non HRMs are easier to play, there, I've said it." - Gil Ayan... AND HE"S IN GOOD COMPANY!
Black chassis' availble: http://cepedals.com/Dumble-Style-Chassis.html
Black chassis' availble: http://cepedals.com/Dumble-Style-Chassis.html
Re: ODS in Progress
Ok cool, I figured it was a popping or transient thing.odourboy wrote:I assume that's minimize popping when the relays are energized. Never used them myself.ChrisM wrote:Adding the ground wire made the PAB switch work.
Whats the point of the 100nF caps?
Glad you got the PAB relay firing. I've never understood why that switch was ungrounded in 124.
So I take it you didn't follow #124 for the back panel switches? Cause it really makes no sense how it is stock, at least to me.
Re: ODS in Progress
No, I didn't follow that. In fact, if you look at the 124 schematic I posted, that aspect is specifically identified:ChrisM wrote:Ok cool, I figured it was a popping or transient thing.odourboy wrote:I assume that's minimize popping when the relays are energized. Never used them myself.ChrisM wrote:Adding the ground wire made the PAB switch work.
Whats the point of the 100nF caps?
Glad you got the PAB relay firing. I've never understood why that switch was ungrounded in 124.
So I take it you didn't follow #124 for the back panel switches? Cause it really makes no sense how it is stock, at least to me.
https://tubeamparchive.com/download/file.php?id=3918
"Let's face it, the non HRMs are easier to play, there, I've said it." - Gil Ayan... AND HE"S IN GOOD COMPANY!
Black chassis' availble: http://cepedals.com/Dumble-Style-Chassis.html
Black chassis' availble: http://cepedals.com/Dumble-Style-Chassis.html
Re: ODS in Progress
The OD initially wasn't working. Soon found two reversed wires coming from level/ratio, OD was then working. The PAB (pre-amp-boost) relay switch wasn't working either. Found an error in the schem/layout that stopped the switch from working. Fixed that little issue and the PAB was working as well.
Originally the sound wasn't anything to write home about. The clean was ok and the OD was bad. The OD was crunchy and had too much highs, not smooth. I figured I was in for a long haul of tweaking, Dumble's are notorious for taking a long time to tweak right....I played around with the OD input trimmer and found my sweet spot. OD was a little better. Still overall the amp lacked though.
As I have read quite a few times the voltages are critical in these amps . V1 must be 190V, V2 200V and V3 280V/290V for this particular build. It took a long time of tube swapping and resistor string changes to get the voltages spot on. In the end I found three perfect tubes that got me the voltages I need and had a really great tone. I went through a lot of tubes trying to get the "right" tone and the correct voltages.
V1 - I used a really old 12AX7 I pulled from a radio. It is definitely vintage, no noise issues though. It is clear and articulate, good punch.
V2 - Mullard Reissue. This tube really smoothed out the OD channel. It is a dark smooth tube so it did the perfect thing to the OD. The OD is very smooth now.
V3 - Sovtek LPS here. It seems to do the job well. I balanced the plate voltages using the PI trimmer. The harmonics are great, lots of second order.
In the end the dropping resistors stayed stock and just swapping tubes got me the correct voltages on the plates. I never thought voltages played such a critical role in the sound but this amp made me beleive.
The amp is so amazing! My favorite to date for sure. The sound is great, it is very much a blues/jazz/rock amp. Yet it is very versatile and can get a range of sounds for these genres. Very sensitive, controls and switches are very effective.
Even though I dont have a head cab or cabinet I will record some clips tomorrow. I got a 112 right now with a crappy Celestion. Even with a poor speaker the amp sounds great. Full report on tone and clips tomorrow...
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... CFront.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... SCBack.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... DSCTop.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... /ODSC2.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... /ODSC3.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... /ODSC1.jpg[/img]
Originally the sound wasn't anything to write home about. The clean was ok and the OD was bad. The OD was crunchy and had too much highs, not smooth. I figured I was in for a long haul of tweaking, Dumble's are notorious for taking a long time to tweak right....I played around with the OD input trimmer and found my sweet spot. OD was a little better. Still overall the amp lacked though.
As I have read quite a few times the voltages are critical in these amps . V1 must be 190V, V2 200V and V3 280V/290V for this particular build. It took a long time of tube swapping and resistor string changes to get the voltages spot on. In the end I found three perfect tubes that got me the voltages I need and had a really great tone. I went through a lot of tubes trying to get the "right" tone and the correct voltages.
V1 - I used a really old 12AX7 I pulled from a radio. It is definitely vintage, no noise issues though. It is clear and articulate, good punch.
V2 - Mullard Reissue. This tube really smoothed out the OD channel. It is a dark smooth tube so it did the perfect thing to the OD. The OD is very smooth now.
V3 - Sovtek LPS here. It seems to do the job well. I balanced the plate voltages using the PI trimmer. The harmonics are great, lots of second order.
In the end the dropping resistors stayed stock and just swapping tubes got me the correct voltages on the plates. I never thought voltages played such a critical role in the sound but this amp made me beleive.
The amp is so amazing! My favorite to date for sure. The sound is great, it is very much a blues/jazz/rock amp. Yet it is very versatile and can get a range of sounds for these genres. Very sensitive, controls and switches are very effective.
Even though I dont have a head cab or cabinet I will record some clips tomorrow. I got a 112 right now with a crappy Celestion. Even with a poor speaker the amp sounds great. Full report on tone and clips tomorrow...
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... CFront.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... SCBack.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... DSCTop.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... /ODSC2.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... /ODSC3.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... /ODSC1.jpg[/img]
Re: ODS in Progress
Nice looking build! 
You may know this but let the amp settle in for at least 20 hours or more play time before tweaking anything.
It may settle into something you really like.
As far as the voltages go, I think you are right on the money on how important that is.
Enjoy your new amp!
You may know this but let the amp settle in for at least 20 hours or more play time before tweaking anything.
It may settle into something you really like.
As far as the voltages go, I think you are right on the money on how important that is.
Enjoy your new amp!
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: ODS in Progress
I tired putting a 50nF cap in parallel with the stock 10nF mid cap. This is the so called strat mod.
The difference is fairly subtle when clean but there is a difference. When in OD mode the parallel 60nF cap provides a smooth fatter sweeter tone. The 10nF is a bit more crunchy and edgy. This little mod definitely deserves a push/pull pot.
Still need to try TAD and NOS Jan Phillips tubes in the output.
Regarding the OD...
The the Level pot is linear. Most annoying, it is too sensitive and too much change occurs in the first quarter of the pot's rotation. Gotta get a audio taper. Now while I am getting a audio taper pot should I try a 100K. What is the tonal difference of the 100K over the 250K?
Also should the ratio be audio taper. It doesn't have a great feel/sweep. Anyone try audio taper here?
The difference is fairly subtle when clean but there is a difference. When in OD mode the parallel 60nF cap provides a smooth fatter sweeter tone. The 10nF is a bit more crunchy and edgy. This little mod definitely deserves a push/pull pot.
Still need to try TAD and NOS Jan Phillips tubes in the output.
Regarding the OD...
The the Level pot is linear. Most annoying, it is too sensitive and too much change occurs in the first quarter of the pot's rotation. Gotta get a audio taper. Now while I am getting a audio taper pot should I try a 100K. What is the tonal difference of the 100K over the 250K?
Also should the ratio be audio taper. It doesn't have a great feel/sweep. Anyone try audio taper here?
Re: ODS in Progress
Hi,odourboy wrote:I've never understood why that switch was ungrounded in 124.
many of these early eighties amp have a Rock/Jazz Switch with a PAB position (middle). And as IMHO it is far more convenient to engage the PAB on the front - instead of fumbling around on the back - perhaps Alexander thought the additional switch on the back of these amps would be useless?
Cheers
Max
Re: ODS in Progress
Are you trying to do a faithful reproduction of #124 or just build a great sounding amp? To the best of my knowledge, #124 used a 250KA Level pot and a 100KB Ratio pot. However, I think the 100KA Level pot was more the norm for 80's amps, so by all means try one - you'll should get a slight (couple of dB) rolloff in lower end with the 100KA port. OTOH, the 100KB Ration was more the norm as far as I know (although I think 100KA ratio pot amps are also around).ChrisM wrote:
Regarding the OD...
The the Level pot is linear. Most annoying, it is too sensitive and too much change occurs in the first quarter of the pot's rotation. Gotta get a audio taper. Now while I am getting a audio taper pot should I try a 100K. What is the tonal difference of the 100K over the 250K?
Also should the ratio be audio taper. It doesn't have a great feel/sweep. Anyone try audio taper here?
"Let's face it, the non HRMs are easier to play, there, I've said it." - Gil Ayan... AND HE"S IN GOOD COMPANY!
Black chassis' availble: http://cepedals.com/Dumble-Style-Chassis.html
Black chassis' availble: http://cepedals.com/Dumble-Style-Chassis.html
Re: ODS in Progress
Cool, thanks for the info Brian.odourboy wrote:Are you trying to do a faithful reproduction of #124 or just build a great sounding amp? To the best of my knowledge, #124 used a 250KA Level pot and a 100KB Ratio pot. However, I think the 100KA Level pot was more the norm for 80's amps, so by all means try one - you'll should get a slight (couple of dB) rolloff in lower end with the 100KA port. OTOH, the 100KB Ration was more the norm as far as I know (although I think 100KA ratio pot amps are also around).ChrisM wrote:
Regarding the OD...
The the Level pot is linear. Most annoying, it is too sensitive and too much change occurs in the first quarter of the pot's rotation. Gotta get a audio taper. Now while I am getting a audio taper pot should I try a 100K. What is the tonal difference of the 100K over the 250K?
Also should the ratio be audio taper. It doesn't have a great feel/sweep. Anyone try audio taper here?
The build is a 50W #124. Right now it is 100% stock. Only thing I plan on doing is making the bright switch a 3 way bright switch and adding push/pull mid cap. In the end though I will tweak components to get a great sounding amp. It already sounds superb though!
I dont think I want any more low's cut on the OD. I like a smooth creamy OD tone. Maybe I will just try an audio taper pot.