found a chassis in my storage place :D

[norburybrook]

Yes, i know i said i wasn't gong to build anymore...but............i found a chassis, well 2 actually in my storage. Fortunately one was the same size as my first builds so i had some more front panel labels made from the original artwork with a change of name, so I've no reason NOT to do another build.

Marcus Chassis 2019.jpeg

I got a set of boards from Erwin and some NOS bit's and pieces so I'm going to make a 50w second gen hybrid combo with built in loop for once and going to try EL34's , Im going to give Erwins High/low plate a try too as i too like the high plate cleans. No Jazz, but I'll do the FET on a footswitch again as i think that's great on these amps. So a 3 button foots witch . I'm toying with the idea of using a 6 pin DIN plug and cable and using the 6'th' pin to send 9vDC to the footswitch so I can power a reverb/delay pedal directly from the footswitch. Most of the time with an ODS that's all i need so having it powered and sat next to the footswitch would be great...if it works properly. I did it before and had a socket on the back of an amp I made and it worked fine so I'm hoping sending it down the same cable as the relays shouldn't be an issue. I just added a 9v regulator in parallel with the 5v for the relays, the secondary tap on my transformers are 1A so should be plenty of current to go round.


TBC



M

[didit]

Yes, i know i said i wasn't gong to build anymore...but............

Halo .. won't say I told you so, but will watch with interest.

Supplying 9V power on an extra wire or two should be OK. Small capacitance down at the floor jack output would buffer power into pedals.

Best .. Ian

[10thTx]

Marcus,

Don't know IF you already have a schematic drawn up, but IF you don't ……… you could edit this one to your liking. I added an FX to it. The FET, relay switching & B+ rail is on the 2nd "sheet" of the schematic.

with respect, 10thtx

** EDIT: I changed the schematic to reflect a closer version of what Marcus is stating he is wanting. However, it still needs editing with ExpressSCH.

[norburybrook]

Marcus,

Don't know IF you already have a schematic drawn up, but IF you don't ……… you could edit this one to your liking. I added an FX to it. The FET, relay switching & B+ rail is on the 2nd "sheet" of the schematic.

with respect, 10thtx

cheers but I can't open that file I downloaded Eagle which is supposed to open Sch files but it come sup with an error.

could you convert to pdf, png, jpeg?


M

[10thTx]

IF you are using a MAC, try Jschem which should open the "SCH" file.

http://jschem.bplaced.net/

Please note to look for errors in the drawing and compare it to Talbany's layout. AND I have not "edited" anything on it to reflect your hybrid approach. For example, this shows 6L6's & the jazz/rock switch which I'm understanding that you will change. Also note, that I have seen different values for the FX loop in the Dumble files, so I'm not sure how you're wanting to approach that & whether you will use LNFB in the FX?

Worse case scenario, perhaps you can use Windows PAINT or some comparable program to edit the schematic if Jschem doesn't work for you? While I don't build D-clones, I would be very interested in seeing how you approach this build.

With respect, 10thtx

** EDIT: In addition to the SCH file in the post above, I changed this matching schematic to be a little closer to what Marcus is suggesting. However, it still needs edits such as the EL34 instead of 6L6

[norburybrook]

thanks, I'm on windows 10 pro

I'm going to use Normsters 2nd gen hybrid and make a pre amp board from his ODS HRM on board loop build . Use high plate values from #102 on V1

2nd_gen_hybrid_rev110410_750.jpg

dumble ODS with on board loop.jpg

the loop will be my first so it will be interesting to see how that turns out as these amps are quite complicated already


M

[didit]

Chassis photo shows three noval nine pin holes. Is there a plan for that yet? And what transformers are planned?

Just asking.

Best .. Ian

[norburybrook]

Chassis photo shows three noval nine pin holes. Is there a plan for that yet? And what transformers are planned?

Just asking.

Best .. Ian

Ian,

an Octal to noval convertor plate

https://www.tube-town.net/ttstore/produ ... no_boost=1


So Ill make V3 the loop and the first of the 4 octals will become the p.i. and I'll blank off the last one as I'm doing a 50w Combo

Transformers will be wound by Savino at Inmadout as always. I'm going for standard fender twin PT (320-0-60-320)with an extra secondary aux for relays, matching Fender value choke. OT a 50w push pull that will drive a pair of EL34's or 6L6's


there's method in my madness.


M

[didit]

That was one of possible few educated guesses. Method is good, along with a bit of true madness so perhaps somewhat higher voltage PT than stock Fender?

Best .. Ian

[j0k3335]

no doubt , it will be an interesting thread

good luck for this new project ( ah, I wish to be competent enough to build such project )

[Guy77]

Hi Marcus,excited to see your build unfold and hear your thoughts on how the circuit sounds. Here is another option for adding extra 9 pin socket holes to a 3 hole ODS chassis. 2 holes are drilled a little further back between the 3 holes to create 5 holes. I did this for a JM build several years ago. It saved me a few dollars.

3hole to 5 hole ODS chassis.jpg

Cheers
Guy

[drew]

thanks, I'm on windows 10 pro

The Windows version of the software can be downloaded here: https://www.expresspcb.com/expresssch/

[10thTx]

The Windows version of the software can be downloaded here: https://www.expresspcb.com/expresssch/

And we have an entire thread of editable D-style schematics in the Dumble library here: https://ampgarage.com/forum/viewtopic.php?f=5&t=17449

….. where people can edit the schematics and share modifications (in a schematic format) with others on the forum IF they wish to.

With respect, 10thtx

[norburybrook]

If I'm going with EL34's should I up the voltage? Like the #183 I built recently perhaps 345-0-345 ?


that should give me about 485v on the plates




M

[didit]

If I'm going with EL34's should I up the voltage? Like the #183 I built recently perhaps 345-0-345 ?


that should give me about 485v on the plates

Truly preference, so your choice. As I recall your #183 was to "your taste". Higher output tube plate voltage places them on a different zone on the load curve. Bit less current allowed etc ... that in my somewhat limited experience has response preferable for clean power stage. Not 100% clean, just different. Within sensible range this is somewhat independent of the whether it's EL34/K77/6L6/etc. These all have different responses.

If you liked your #183 power, and it fits what your mind's ear imagines for the next one then proceed. If you want something else, perhaps a lower B+ will be better.

Plan experimenting with higher than typical B+ in a 50W 2nd generation when my (at present too limited) time allows. Early next year is my hope. Have to finish at least two other projects on the workbench before getting into this one.

Best .. Ian