Help with 50 watt OT choice

[jcsifu]

a better choice for tone is to NOT use a hammond.

hammonds are sterile and lifeless. I've had a ton of them - never again outside of keyboard amps for me.

top bore is a dynaco 470s from triode electronics - once you go 470 you never go back!

That might be what I am experiencing, I'm not as impressed as I would like to be with the tones I'm getting. I have been attributing it to the undersized (in my opinion) OT, but maybe you are pointing out the culprit.

Hmmm I don't experience any of that troubles with my Hammond OT. How is the clean channel? If that low end is tight, then it's not the OT's fault. Actually I am satisfied with the OT... I cannot compare with different brands, and perhaps indeed there are better choices. But my amp has a lot of note seperation.. good even pronounciation between treble/mid and bass registers... and above any it maybe sound a bit too woofy at times. But the OT sure is capable of delivering the low end. Especially when I compare it to my other amps. I deleted the bass cap, but now going to solder it back on to tighten the sound up. I built the OTS kit and made sure I did it clean and per dumble lay out. All in all the amp took a while to break in and sounded a bit harsh at the beginning, but that is starting to fade away, the dumble tone is absolutely coming through no doubt.

Also at what point did you start to notice the change in tone/break in? 20 hours? 50 hours?

[jcsifu]

Also, I have 100mf power caps and looking at the 124 pics they are300mf. I have a bag of 70mf 350vollt caps that I could piggie back on those 1 to 1 on the existing 100mf. Maybe I should see if I just need more power cap help for the lows.

[jcsifu]

UPDATE:

The additional 70uf caps are in and I do believe the OD lower end is tighter and clearer when muting notes and chords as well as during faster picking runs. I felt like Bonamassa for a minute there...I do not have the opportunity until next week to take this amp up to warp speed in the studio, but I feel like what I've heard so far is a step in the right direction.

ToneMerc:
I liked your idea of doc each change so I am doing so. I would like to be able to do this by recording but my mac is down with a jammed drive and needs to go to the doctor. I will log it on paper.

I have to run errands and then will do the ht wires.

[Kassie]

That might be what I am experiencing, I'm not as impressed as I would like to be with the tones I'm getting. I have been attributing it to the undersized (in my opinion) OT, but maybe you are pointing out the culprit.

Hmmm I don't experience any of that troubles with my Hammond OT. How is the clean channel? If that low end is tight, then it's not the OT's fault. Actually I am satisfied with the OT... I cannot compare with different brands, and perhaps indeed there are better choices. But my amp has a lot of note seperation.. good even pronounciation between treble/mid and bass registers... and above any it maybe sound a bit too woofy at times. But the OT sure is capable of delivering the low end. Especially when I compare it to my other amps. I deleted the bass cap, but now going to solder it back on to tighten the sound up. I built the OTS kit and made sure I did it clean and per dumble lay out. All in all the amp took a while to break in and sounded a bit harsh at the beginning, but that is starting to fade away, the dumble tone is absolutely coming through no doubt.

Also at what point did you start to notice the change in tone/break in? 20 hours? 50 hours?

Not even... it started to get smoother after 6 hours allready... but it's still ongoing.. I finished it last week. But indeed it was predominantly harsh on the OD circuit.

I actually modded the OTS closer to 124 spec just now. Changed all the anodes to 100k and cathodes to 1.5k. With standard 5uf bypass caps, I have 2 500pfs on the v2 as per two rock crs schematic. Also bear in mind that the OD channel has less bass. And I believe it should be to have a tight focussed sound.

Euhmm.. the filter cap values are a good one.. I replaced the ceriatone ones for F&T's.. and allready could hear a bit of a difference in string seperation and tightness. I just have the stock 220ufs.. I might indeed try out how it works out with extra 100ufs or so. That will bring more HiFi response to the amp indeed. Perhaps at the expense of smoothness, but you can confirm/disconfirm that now.

[jcsifu]

My caps were just 100uf, so the extra 70uf was a nice add. I can't find anything in the 200 range at high voltage so I just ordered 2 100uf 450v f&t to take the place of the 70's. I did notice on the real 124 has 300uf caps, so you could always just tack 100's on and see what happens.

My amp should be well broken in by now then, so if the dress doesn't get me there I think I might start to follow suit with you and move towards the 124 values. I'm gathering the info for the changes as we speak, or is it as simple as just the few tweaks you listed?

I am getting sidetracked with having to put the wiring harness I built last week into a es-335 guitar, I have been procrasting installing it. It is not a fun event.

I still hope to have time this week and weekend to do those ht wires, but it might not be today.

Do you find that the 500pf snubs are a good match and leave enough high attack? Or have you even had enough play time to see?

[jcsifu]

repeat

[Kassie]

My caps were just 100uf, so the extra 70uf was a nice add. I can't find anything in the 200 range at high voltage so I just ordered 2 100uf 450v f&t to take the place of the 70's.

My amp should be well broken in by now then, so if the dress doesn't get me there I think I might start to follow suit with you and move towards the 124 values. I'm gathering the info for the changes as we speak, or is it as simple as just the few tweaks you listed?


I still hope to have time this week and weekend to do those ht wires, but it might not be today.

Do you find that the 500pf snubs are a good match and leave enough high attack? Or have you even had enough play time to see?

Rule number 1. Never rush and take your time slowly. Thats how HAD did it.

Yeah, first start with lead dress as per an original dumble. I watched 133 pictures on the facebook channel. And also 124 pictures. I changed quite a bit from the ceriatone lay out (filaments up in the air, v1/v2 anodes/cathodes close together, and PI wires close together to the back of the chassis and the grid resistors soldered across the tube socket). I will upload you an image of my build tomorrow so you can see.

The v2 snubbers is to taste.. at first the amp was real gritty trebly.. so I actually went with 500pf (first triode) and 700pf (second triode). Then I discovered that a tungsol tube probably wasn't the thing for v2 (but I like it in v1 a lot). So I put a JJ803s in it.. then I could take 200pf off. And it sounded good. I like that velvety dumble lead tone.. though it still has nice high end attack if you want it. You can do that by upping the ratio (7) and lowering the Level (3) for more of a rock type sound, and the amp gets more presence by upping the master volume anyways.

Then I went with the former mentioned anode/kathode resistor changes (all dale rn65d btw). And the amp got much more low mids and seemed fatter. But it also had a bit more treble. I just left the 500 caps alone cus it seems fine with me now. I also decreased the 150k slope resistor on the OD level for a 100k (dr Ika).. a bit higher gain on the OD volume.. so the OD is a bit more balanced with the clean channel in terms of perceived volume. (even with the 2 500pfs I can still make it gritty by adding the bright switch, but I am just going for an even smoothness or brightness for both channels. So if you kick in the drive, i don't like extra treble added by the drive itself). Now if the amp turns out really smooth when it's fully broken in.. I can always lower the bright caps, or put a tungsol into v2 again.

If there is a mod I would highly recommend it would be the LNFB switch on v1. As per dr. Ika mod. That really gives you a fat gain boost into the amp.

If I were you I would just buy F&T 220mfd's. Then you can always decide to up it to 300.

Allright, long post.. pictures tomorrow.. for now goodnight.

[jcsifu]

Rule number 1. Never rush and take your time slowly. Thats how HAD did it.

Yeah, first start with lead dress as per an original dumble. I watched 133 pictures on the facebook channel. And also 124 pictures. I changed quite a bit from the ceriatone lay out (filaments up in the air, v1/v2 anodes/cathodes close together, and PI wires close together to the back of the chassis and the grid resistors soldered across the tube socket). I will upload you an image of my build tomorrow so you can see.

The v2 snubbers is to taste.. at first the amp was real gritty trebly.. so I actually went with 500pf (first triode) and 700pf (second triode). Then I discovered that a tungsol tube probably wasn't the thing for v2 (but I like it in v1 a lot). So I put a JJ803s in it.. then I could take 200pf off. And it sounded good. I like that velvety dumble lead tone.. though it still has nice high end attack if you want it. You can do that by upping the ratio (7) and lowering the Level (3) for more of a rock type sound, and the amp gets more presence by upping the master volume anyways.

Then I went with the former mentioned anode/kathode resistor changes (all dale rn65d btw). And the amp got much more low mids and seemed fatter. But it also had a bit more treble. I just left the 500 caps alone cus it seems fine with me now. I also decreased the 150k slope resistor on the OD level for a 100k (dr Ika).. a bit higher gain on the OD volume.. so the OD is a bit more balanced with the clean channel in terms of perceived volume. (even with the 2 500pfs I can still make it gritty by adding the bright switch, but I am just going for an even smoothness or brightness for both channels. So if you kick in the drive, i don't like extra treble added by the drive itself). Now if the amp turns out really smooth when it's fully broken in.. I can always lower the bright caps, or put a tungsol into v2 again.

If there is a mod I would highly recommend it would be the LNFB switch on v1. As per dr. Ika mod. That really gives you a fat gain boost into the amp.

If I were you I would just buy F&T 220mfd's. Then you can always decide to up it to 300.

Allright, long post.. pictures tomorrow.. for now goodnight.

The pics will be nice to see, thanks!

I can see why people put the snubbers on 3 way switches, it would be useful to find the right combo.

I already did the V1b switch, I did 500pf-0pf-.05(original cap). I like no feedback, the 500pf is barely noticeable though.

I am really looking forward to seeing your lead dress examples and learning from your pics. I have never worked on a Dumble style amp and I am appreciative of your time and effort to bring me up to speed here.

[10thTx]

I am going to suggest something that may or may not be useful to you. Safely use two wires with insulated alligator clips to try this.

Try putting a 120p cap across the plate resistor going into the LTPI. ("enhance cap" 82p to 250p range)

I found it added smoothness to the high end in my 3 amps without removing the high frequency.

You can read some reviews about this by others also here:
http://www.el34world.com/Forum/index.php?topic=12723.0

I am not sure it works on every amp, but has been useful to me every time I have tried it.

With respect, Tubenit

[Kassie]

The pics will be nice to see, thanks!

I am really looking forward to seeing your lead dress examples and learning from your pics. I have never worked on a Dumble style amp and I am appreciative of your time and effort to bring me up to speed here.

This is my first dumble build as well, I consider myself a hobby builder, and don't have too much knowledge like other aclaimed makers here on the forum. I have just build a nice working amp. And went with recommendations here on the forum. Here some pics for you.

[IMG472]http://i932.photobucket.com/albums/ad16 ... C02310.jpg[/img]

[IMG:800:600]http://i932.photobucket.com/albums/ad16 ... C02305.jpg[/img]

[IMG:800:600]http://i932.photobucket.com/albums/ad16 ... C02309.jpg[/img]

[IMG:800:600]http://i932.photobucket.com/albums/ad16 ... C02306.jpg[/img]

note, high current or alternating current wires tightly twisted for magnetic field cancelling, as well as added firmness so they won't resonate and create a larger magnetic field. Note PI wires to the back of the chassis, grid stoppers and connection with shrink tube on power tube sockets, they are not crosstalking with anode (OT primary). OT primary is tightly twisted as well. Note filament up in the air (especially important for v1, since people got trouble on the OD channel with crosstalk when the anode/kathodes are too close to the filament as per Ceriatone.

[jcsifu]

I have a work emergency so it will be a long day for me today, just wanted to let you guys know I will have to wait until late tonight to reply.

[jcsifu]

I am going to suggest something that may or may not be useful to you. Safely use two wires with insulated alligator clips to try this.

Try putting a 120p cap across the plate resistor going into the LTPI. ("enhance cap" 82p to 250p range)

I found it added smoothness to the high end in my 3 amps without removing the high frequency.

You can read some reviews about this by others also here:
http://www.el34world.com/Forum/index.php?topic=12723.0

I am not sure it works on every amp, but has been useful to me every time I have tried it.

With respect, Tubenit

So I would bypass the 100k or the 110k after the pi trimmer?

[jcsifu]

The pics will be nice to see, thanks!

I am really looking forward to seeing your lead dress examples and learning from your pics. I have never worked on a Dumble style amp and I am appreciative of your time and effort to bring me up to speed here.

This is my first dumble build as well, I consider myself a hobby builder, and don't have too much knowledge like other aclaimed makers here on the forum. I have just build a nice working amp. And went with recommendations here on the forum. Here some pics for you.

[IMG472]http://i932.photobucket.com/albums/ad16 ... C02310.jpg[/img]

[IMG:800:600]http://i932.photobucket.com/albums/ad16 ... C02305.jpg[/img]

[IMG:800:600]http://i932.photobucket.com/albums/ad16 ... C02309.jpg[/img]

[IMG:800:600]http://i932.photobucket.com/albums/ad16 ... C02306.jpg[/img]

note, high current or alternating current wires tightly twisted for magnetic field cancelling, as well as added firmness so they won't resonate and create a larger magnetic field. Note PI wires to the back of the chassis, grid stoppers and connection with shrink tube on power tube sockets, they are not crosstalking with anode (OT primary). OT primary is tightly twisted as well. Note filament up in the air (especially important for v1, since people got trouble on the OD channel with crosstalk when the anode/kathodes are too close to the filament as per Ceriatone.

Wow, that is super clean! Very impressive for a first shot at a dumble. You clearly put a lot of time and thought into it. This is like a crash course in Dumble and I am very appreciative for your time and pics. I will be studying these pics and comparing to the limited schematics and the of OTS and 124 layouts I have in my files. This should keep me busy until my iron arrives for the swap out.

I will post results as they occur.

[Kassie]

Wow, that is super clean! Very impressive for a first shot at a dumble. You clearly put a lot of time and thought into it. This is like a crash course in Dumble and I am very appreciative for your time and pics. I will be studying these pics and comparing to the limited schematics and the of OTS and 124 layouts I have in my files. This should keep me busy until my iron arrives for the swap out.

I will post results as they occur.

Thanks, which Iron did you choose? Curious to the result. This is my second amp and it's a lot better built then my first amp (express model). I bought a soldering station, good flowing solder and that makes all the difference. For desoldering I use a pump and desoldering braid (wick or litze don't really know the official english term)... that also makes a big difference if you want to redo things. Just make the connections clean again and resolder. But most of all, take your time and don't hurry. Then it's still faster than having to redo things.

Ohh and if you want some more detailed pics of other parts of the circuit feel free to ask. Good luck!

[jcsifu]

Wow, that is super clean! Very impressive for a first shot at a dumble. You clearly put a lot of time and thought into it. This is like a crash course in Dumble and I am very appreciative for your time and pics. I will be studying these pics and comparing to the limited schematics and the of OTS and 124 layouts I have in my files. This should keep me busy until my iron arrives for the swap out.

I will post results as they occur.

Thanks, which Iron did you choose? Curious to the result. This is my second amp and it's a lot better built then my first amp (express model). I bought a soldering station, good flowing solder and that makes all the difference. For desoldering I use a pump and desoldering braid (wick or litze don't really know the official english term)... that also makes a big difference if you want to redo things. Just make the connections clean again and resolder. But most of all, take your time and don't hurry. Then it's still faster than having to redo things.

Ohh and if you want some more detailed pics of other parts of the circuit feel free to ask. Good luck!

Went with Classictone 18001