ODS options

[Aurora]

I'm planning an ODS build, and are in the process of finding parts, - transformers will likely be Classictone, but 50 or 100W is yet to be decided by the delinquent.. ( my son) A few quiestions, though..

Buffered loop... I can see the need for a buffered loop, but several options of SS buffers have been presented, like the Kleinulator.. I'm thinking that since effects will most likely be Solid state anyway - why tube buffering? Without a tube buffer , I can find chassis from a couple of vendors - but only with 3 noval sockets.... and no holes for effect pot's...

Reverb - I found a nice layout with tube buffer and a SS reverb circuit - nice options- but since I'm not much of a guitar player myselv - how much is reverb really used these days?
I also adds to the chassis problem.... any vendors of blank chassis of suitable size???

[stelligan]

Is the aforementioned delinquent planning to play out at clubs/halls or just at home? If mostly at home, having extra bits externally like : dumleator, effects units, etc. is not a big deal. If this is going to be a grab and go combo and he plays clean - I would opt for a 100 watt 1 x 12 with at least a loop internal - less to haul around(heavy). Young people do not mind multiple trips to haul their gear. Geezers like me despise it. If I can't get my stuff on stage in one trip, it's a drag......

My 2 cents, 100 watts is more important than all other factors if he plays clean at all. Great master volumes on these things and a lot of the action is in the preamp. If he likes to grind and rock - he may want 50 watts to get the power amp and speakers more into the picture.

I am not a reverb guy - so have no opinion for you there...

Happy building.

[Mark]

It depends on which version of the ODS you are going to build, but for a non HRM version, overloading cathode follower triode is gold!

Do a search others have concurred with this effect. Basically extra compression and a thicker tone. If the amp is to be HRM then feel free to use a SS effects loop, the Metro loop gets a good rap.

[talbany]

You will notice a few things when you buffer the signal into either a tone stack (filter network) or outboard gear or in spring reverb circuits!. Since we know impedance is frequency dependent driving either the stack or the loop with a follower your shooting for a zero source impedance to achieve it's theoretical frequency response. If it's driven from too large a source impedance, not only will there be a loss of gain and typically quite a few dB loss of the highs.The cathode follower prevents this. A good example of this would be the legendary fender 5F6A (Bassman)circuit. Instead of driving outboard gear it drives the tone stack!..This is why these amps have such a wider tonal range from a heavy low end (bass amp) to searing highs and therefore an efficient working stack because the lower source impedance allows the stack to work as designed.
Like Mark states!
The other thing the cathode follower does is (when driven hard) generates 2nd order harmonics!. This provides several tonal qualities.1 gives the amp a natural compression that feels organic and 2 a fatter sound (great for single coils) Again another reason why these old Marshall/Bassman circuits still sound great when driven into clipping!

If on the other hand you play at bedroom levels and like the sound of the lower impedance circuit and don't need all the signal restored after the effects hey go for it!..If your son plays loud and in band situations, a D-lator is a necessary evil IMO!.

By simply adding a 250KA pot across the send and return jacks you now have a mix control for both clean and wet signals in parallel that is in phase and essentially works like your treble pot on the tone stack (Mixes treble and bass frequency's) There are other ways to do this (with dual pots) but works OK and is an easy install. I added this to all my internally built loops

Tony

[martin manning]

250k pot? Did you find that to be an improvement over the 25k pot as used in the Boogie blender here: https://tubeamparchive.com/viewtopic.ph ... highlight= ?

[amplifiednation]

I have ODS chassis back in stock. They will fit 50w or 100w classic tone without drilling any additional holes.

[Guy77]

It depends on which version of the ODS you are going to build, but for a non HRM version, overloading cathode follower triode is gold!

Do a search others have concurred with this effect. Basically extra compression and a thicker tone. If the amp is to be HRM then feel free to use a SS effects loop, the Metro loop gets a good rap.

This is definitely true! That extra tube in the buffered effects loop adds so much extra good tone ! I did not need this when building my JM amp because it already had that extra tube in the schematic.

Cheers

Guy

[talbany]

250k pot? Did you find that to be an improvement over the 25k pot as used in the Boogie blender here: https://tubeamparchive.com/viewtopic.ph ... highlight= ?

Martin
Yes I have been down the 25K road in the beginning. The main issue I had was with my outboard gear set wet I found a serious null point in the pots rotation where it became too sensitive!. So I am not sure why the Boogie/Nomad/Subway Rocket method did not work well other than to say the Boogie loop's buffer is transistor driven.Maybe you have an idea why this did not work with D-lator? I have 2 amps with 2 different blender pots.
My 2nd generation has the dual pot ( ground on both ends) like the one posted. It has no null spots in full rotation and can run the outboard gear as wet as I want so it works best.

The other is my Bluesmaster it has the 250k 2-35A pot also has no null point in the rotation, however, I am not able to run my outboard as wet as the dual pot but close enough!
I figured Fender uses 220k mixing resistors to mix in clean and effects into the PI so that is why I tried the 250k pot.Works OK and left it in.

Tony

Dumbleator-ENGLized-ver1.bmp

[Aurora]

Interesting info... thanks, guys... Now the chase for a cab with 4 ECC holes, or a suitable cab blank.......