Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Misc Schematics and Layouts => Topic started by: tubenit on March 05, 2017, 08:32:41 am

Title: 1 watt Marshall
Post by: tubenit on March 05, 2017, 08:32:41 am

There is a 27 page thread on the Amp Garage about this amp.  I've not built it and have no current plans to.  I took the most "current" schematic they posted on the thread and redrew it in a way that was easier for me to follow.

http://ampgarage.com/forum/viewtopic.php?f=9&t=24671&hilit=JTM1+1W+Marshall&start=390 (http://ampgarage.com/forum/viewtopic.php?f=9&t=24671&hilit=JTM1+1W+Marshall&start=390)

I don't know if this is a "proven" idea or not?

Discovered from the guy that drew up the schematic that 56k is correct for the grid to cathode on the phase invertor.

With respect, Tubenit

Title: Re: 1 watt Marshall
Post by: smackoj on March 05, 2017, 11:58:03 pm

Thanks for your effort Tubenit. It seems to me that building an amp with what looks like a lot of time and energy invested, doesn't really compute to only produce 1 watt of power for use. Just one old man's opinion mind you. 

Title: Re: 1 watt Marshall
Post by: tubenit on March 06, 2017, 02:00:46 pm

Here is a YouTube that is a 1 watt Marshall. 

https://www.youtube.com/watch?v=w71tBeuLn2Y (https://www.youtube.com/watch?v=w71tBeuLn2Y)

! No longer available (http://www.youtube.com/watch?v=8P2OmLNUAvE#)

CHECK for ERRORS with this layout!  Compare with schematic.  IF there is a discrepancy, then go with the schematic.

With respect, Tubenit

Title: Re: 1 watt Marshall
Post by: tubenit on March 06, 2017, 04:49:07 pm

OK,  I think IF I were to try and build this, I'd use this schematic and layout.

CHECK for ERRORS!  Compare layout with schematic.  IF there is a difference, then I'd go with the schematic.   This is a DRAFT design!

Musical Power Supplies has a 5 watt push/pull OT for use with 12AU7 power tubes. 

http://www.ebay.com/itm/OT5PP-Push-Pull-Tube-Output-Transformer-Low-Power-22K5-4-8-16ohm-5VA-Imported-/152426606383 (http://www.ebay.com/itm/OT5PP-Push-Pull-Tube-Output-Transformer-Low-Power-22K5-4-8-16ohm-5VA-Imported-/152426606383)

This PT might work but you'd probably need a larger dropping resistor between node B and node C on the B+ rail?  190-0-190 

http://www.ebay.com/itm/PT190-2-USA-POWER-TRANSFORMER-TUBE-AUDIO-380Vac-190-0-55-190-x120mA-/162017736572 (http://www.ebay.com/itm/PT190-2-USA-POWER-TRANSFORMER-TUBE-AUDIO-380Vac-190-0-55-190-x120mA-/162017736572)

With respect, Tubenit

Title: Re: 1 watt Marshall
Post by: jerrydyer on August 29, 2018, 03:24:07 pm

Anyone have the jmp1h schematic. I havr low low volume.

Title: Re: 1 watt Marshall
Post by: shooter on August 29, 2018, 08:40:34 pm

um, original post, 1st image should get you close enough to fix

Title: Re: 1 watt Marshall
Post by: Ampmod on January 15, 2022, 10:52:43 am

Quote from: tubenit on March 05, 2017, 08:32:41 am

Discovered from the guy that drew up the schematic that 56k is correct for the grid to cathode on the phase invertor.

I see no One answered this so Far, 56k Ohm resistor is OK, because it is "bootstraped" and ir does not make load at stage before it.

P.S. Schematic with drawed DC voltages on Phase Inverter is worg. R16 and R11 are Equal resistors, current through them is the same. But showen Voltages Drops very different (42V and 29V); it is wrong.

Title: Re: 1 watt Marshall
Post by: shooter on January 15, 2022, 03:17:56 pm

 :BangHead:

Title: Re: 1 watt Marshall
Post by: voodoochild2b13 on January 24, 2022, 07:39:32 am

hello i get that schema from another forum. it made by mattec.
i home it Will help somebody. sorry for my english

Title: Re: 1 watt Marshall
Post by: distortionhead on January 24, 2022, 11:11:22 am

https://drive.google.com/file/d/1vBgXbHo5nMUCXZvkNHStyjzyi3ZHOUyI/view
Link to the pdf version of the above docs