BAJA Mars Hall 1959 plexi amp overdrive pedal 9v 090318

bajaman · Post by **bajaman** » 09 Mar 2018, 09:46

Hot off the drawing board - vero layout to follow shortly

This is the amplifier that after the VOX AC30 changed the sound of British rock for ever - based on the circuit of the 1959 Fender Tweed Bassman it used the European EL34 entode output tubes because they were a lot easier and most probably a lot cheaper for Jim Marshall to purchase in post WWII Great Britain.
enjoy and have fun

bajaman

Frank_NH · Post by **Frank_NH** » 09 Mar 2018, 15:16

Whoo hoo. I'm running out of TL064s!! Thanks again.

HEAD · Post by **HEAD** » 09 Mar 2018, 16:31

Frank_NH wrote:Whoo hoo. I'm running out of TL064s!! Thanks again.

... still waiting for mine to arrive. Running out of 100k pots, too!

bajaman · Post by **bajaman** » 10 Mar 2018, 03:39

: Baja Mars Hall 1959 vero cuts.png (7.4 KiB) Viewed 7213 times

roseblood11 · Post by **roseblood11** » 10 Mar 2018, 15:20

What's the advantage of the tl062 over the 072 or other opamps here?

HEAD · Post by **HEAD** » 10 Mar 2018, 16:45

... lower slew rate -> less harsh sound.

Frank_NH · Post by **Frank_NH** » 10 Mar 2018, 23:59

Quick question. Did you intend to have 100K to ground for the JFET buffer?

bajaman · Post by **bajaman** » 11 Mar 2018, 08:45

Quick question. Did you intend to have 100K to ground for the JFET buffer?

Good spotting - Yes - I found it improves the signal to noise ratio as the fet is now running at a much lower current.
cheers
bajaman

Frank_NH · Post by **Frank_NH** » 11 Mar 2018, 18:18

OK. Yes, 100K will lower the current flow, though wouldn't the higher resistance introduce more noise?

Well I can simulate it in LTspice and see. Thanks!

287m · Post by **287m** » 13 Mar 2018, 10:23

first try in perf

FausterCraster · Post by **FausterCraster** » 13 Mar 2018, 12:33

Baja this is the best pedal I ever played !!

Below my (verified) 24x18 hole board. Enjoy it !!

gght · Post by **gght** » 14 Mar 2018, 00:20

Anyone have clip to listen to this??

bajaman · Post by **bajaman** » 14 Mar 2018, 02:57

A couple of small errors on the original vero - this one is verified - i built it and it works well

: Baja Mars Hall 1959 vero cuts.png (7.4 KiB) Viewed 6981 times

bajaman · Post by **bajaman** » 14 Mar 2018, 05:00

some pictures of my build - recycled enclosure again

cheers
bajaman

gght · Post by **gght** » 14 Mar 2018, 18:21

Sweet

HEAD · Post by **HEAD** » 21 Mar 2018, 18:37

287m wrote:first try in perf

Edit: Made a mistake and fixed it.

95H · Post by **95H** » 22 Mar 2018, 08:01

Hallo,

what type of capacitors are used away from the 1uF multilayer ceramic?

287m · Post by **287m** » 22 Mar 2018, 11:59

95H wrote:Hallo,

what type of capacitors are used away from the 1uF multilayer ceramic?

MLCC, like this

95H · Post by **95H** » 22 Mar 2018, 12:52

287m wrote:
95H wrote:Hallo,

what type of capacitors are used away from the 1uF multilayer ceramic?
MLCC, like this

The question was what type of caps for the other values than the 1uF. Except electrolyte .

287m · Post by **287m** » 22 Mar 2018, 13:16

I build all with MLCC, because all i have.
But you can use poly box caps and/or ceramic for some pF value

BAJA Mars Hall 1959 plexi amp overdrive pedal 9v 090318 [documentation]