Poor mans SSS ~

[talbany]

Do a BM PI (and a tone stack of your choosing) on one channel and the other do Dumbles High gain mod (internal channel/boost switching)100w EL-34's & Marshall transformers..No need for a pedal then..Bluesmaster/tweaked JCM800 Twisted Evil

I was thinking more like 2 discrete channels..This way you can voice the 2 without them effecting each other,(mix them in @ PI)which is why I think it would be cooler than an ODS with the cascading stages..

Are either of these sort of what you are thinking?

With respect, 10thtx

Thats kind of what I was thinking,accept without the OD channel on V2..The JCM800 (high gain) would be the overdrive channel so the switching would just be on the inputs and summed (w/220k/470k) at the Pi..Also think like a low plate (classic or skyliner) for the clean channel..You could tweak both channels independently if you wanted..

The OD/JCM800 channel is not really for me.

Aaron and others
My interpretation of the Dumble High gain mod was very much like a JCM800,but much smoother and more low mids and mo gain on tap..My problem was I couldn't get it to clean up all that well,but thought it would make a killer overdrive channel (especially for the Marshall lovers)..
Then again like you say too each is own!!

Tony

[Aaron]

The OD/JCM800 channel is not really for me.

Aaron and others
My interpretation of the Dumble High gain mod was very much like a JCM800,but much smoother and more low mids and mo gain on tap..My problem was I couldn't get it to clean up all that well,but thought it would make a killer overdrive channel (especially for the Marshall lovers)..
Then again like you say too each is own!!

Tony

Hi Tony,

I found exactly the same thing. More lower mids-a lot more gain.
It doesn't sound bad, I like riding the volume on the guitar and this channel is more balls to the wall
Good for a Darkness tribute band.

Aaron

[10thTx]

Hopefully this is getting closer.

THANKS for sharing your ideas!

with respect, 10thtx


I also included an idea based of DaGeezer HoSo56 using a 5879 in V1.


The editable SCH versions are here:
https://tubeamparchive.com/viewtopic.ph ... 767#305767

[talbany]

You got the layout right but you dont have the high gain side right..Here is the D-High gain side below.. ...(I use the term JCM800 since it looks like Dumble just tweaked that topology to his liking!!)
The other change I would do is reverse the 220k/470K and put the 470k on the high gain channel..Really you can use both 220k's since this will give you enough isolation at the PI but I prefer the 470K (as Dumble does) to help smooth and focus things before it hits the PI..

The real beauty of this design is your not limited in your ability to tweak each channel (especially clean)..

If the JCM side is too gainy for you there are all kinds of things you can do like tweak the 45K network (or use a 100k pot there)after V1B or go to a lower gain tube in V1 so don't be afraid to tweak there...Another cool reason why I like this design is the High gain side has a cathode follower in it..since CF generate 2nd order (and smooths things) it helps to fatten the tone on single coils.. ...Since most people here (including myself) like the low plate designs better for single coils along with the CF in the OD side this amp should work great with Strats or at least IMO better than the ODS in some cases..
BTW.. I don't have a problem with adding the loop on the clean channel but not sure how it might interact with the high gain side..I would recommend trying it first with an external loop to see how it works for you..

Side Note:.. You don't need a buffer on the high gain side (to drive your effects) since the CF is already driving the stack at a low enough impedance,you would just need a return/recovery amp after..

It makes perfect sense that Dumble would do his version of the JCM for a high gain channel,since the JCM was such a popular amp in the 80's and for some still a popular high gain design!!

From a players/builders/tweaker platform this amp could be better than the Ripper...IMO

Good Luck

Tony

[10thTx]

Tony,

THANK you again for your abundance of knowledge, experience and willingness to share! I appreciate the incredible contributions you make to this forum.

With respect, 10thtx

[jelle]

To my ears this amp has some other things going on in there than just tonestacks and PI's. I maybe wrong??

Rich with a little gumption all the info needed to build a UP can be found in this forum, although some folks expect all info to be spoonfed to them including a layout. No need to get ticked off because it was suggested to use the search function though.

I can't speak for anyone else but when asked by either the owner or a tech to not publicly disclose info about about a certain D amp, I abide by it.

One last thing which I have said in the past concerning the UP is that just because Dumble touched it folks expect to see some grand scheme which is much more than what's there, when in reality the mod is conceptually rather simple in the platform of his work.

Sometimes the point is reached to where either you stay on the porch and continue to whine and wait for someone to throw you a bone or you jump off the porch and get it youself.



TM

Thanks! I do not see how my effort to help people and give them the exact same information as I was given has to result in the response that followed.

I would have been better off not responding. I will consider that next time.

[talbany]

I would have been better off not responding. I will consider that next time.

Jelle
I think the thing we really need to keep in mind when posting...Even though you might be directing your post as a reply there are usually hundreds and possibly thousands that may read it and get something useful from it...I know I always do!

To Everyone!!
We all know the search function here Put us in a bad mood but I am sure if we ask politely someone who might remember where that thread might be can help out!!

THANK you again for your abundance of knowledge, experience and willingness to share! I appreciate the incredible contributions you make to this forum.

Your Welcome and THANKS for all the work and time on the schematics you've posted over the years!!..I've used them quite often!!

Tony

[67plexi]

This is a poor man's SSS if you build enough if these I guaranty you will be dirt poor.

[crafty1]

Jelle,

You replied to my post the other day on this thread regarding my question about the UP amp. I guess at the time it was not exactly the response i was looking for however my posting that followed was somewhat agressive and uncalled for and i do apologies for my for comments directed at you.
The information and time that guys like yourself, Tony and many others put into this forum is very much appreciated.

I see a lot of new comers to the forum looking to dip their toe into the world of D style amp building/amp mods.
Why i was asking about the UP amp is that out of all the D style amp topologies it looks to be a ( shall i say ) less overwhelming platform to start with rather than dive straight into an ODS or SSS. Some may disagree.
You can still get yourself a silver face bandmaster or Bassman relatively cheap, make the component value changes without too much intrusion to the inner workings, experiment and adjust to taste while gaining valuable knowledge along the way. If it doesn't turn out as planned you can always put the amp back to stock.

I would be happy to draft a schem and place in the file section if people are interested. If not i will drop it and move on.

Respectfully

Rich

[da Geezer]

Jelle,

You replied to my post the other day on this thread regarding my question about the UP amp. I guess at the time it was not exactly the response i was looking for however my posting that followed was somewhat agressive and uncalled for and i do apologies for my for comments directed at you.
The information and time that guys like yourself, Tony and many others put into this forum is very much appreciated.

I see a lot of new comers to the forum looking to dip their toe into the world of D style amp building/amp mods.
Why i was asking about the UP amp is that out of all the D style amp topologies it looks to be a ( shall i say ) less overwhelming platform to start with rather than dive straight into an ODS or SSS. Some may disagree.
You can still get yourself a silver face bandmaster or Bassman relatively cheap, make the component value changes without too much intrusion to the inner workings, experiment and adjust to taste while gaining valuable knowledge along the way. If it doesn't turn out as planned you can always put the amp back to stock.

I would be happy to draft a schem and place in the file section if people are interested. If not i will drop it and move on.

Respectfully

Rich

Rich's comments reflect my thoughts as well....couldn't have said it any better.

Again, with respect....G

[M Fowler]

In my case I'm not a big channel switching type of guy so I prefer basic amps of which the Fender two channel type chassis is perfect for say tweed on one side and higher gain on other side.

I do like Aaron's schematic with JCM800 2204 and clean perfect amp for my use.

The guys & ladies on this forum are great and provide so much information it has me spinning in place trying to concentrate on one project instead of all the amps I could be building

Mark

[jelle]

Thanks guys for responding. Accepted.

Please realize that my messages are often short because I typically post from an Iphone.

Good luck with the build.

Jelle

[andresound]

Hi guys,
This is a VERY old thread. Was searching for info on a Dumble/JCM type conversion on a 68 bassman I acquired as a donor (I always try buy old fenders as donors, because I believe their iron is relevant). Long story short... I lent a pro muso friend my first 2nd Dumble type build (ODS in a Bassman 50 chassis #40) amp. I had to fight to get it back!!! I will never sell it, because David Root helped me with it.
Friend asked for me to build a similar amp. Because he only used the clean channel of the ODS, but does own a Marshall combo, I am contemplating building the “modded bassman” by Aaron in from this thread.
What are the thoughts on a 12AT7 as apposed to 12AX7. My ODS based on #40, had the 12AT7 PI. Higher current capabilities, translates to “bigger” sound?
Please remember, I am a nube amongst the esteemed contributors on TAG (for whom I am so grateful). ALL suggestions are welcome.

[M Fowler]

Did any of my donated Dumble value pots go into your David Root special amp? If yes, that would be cool to know, David was a great person to many of us.

Mark

[andresound]

Sorry Mark, was a good few years ago. Yes... great man and his “mojo” will live with me till I die