2061x Lead & Bass Schematic & Layout

[Mickey_C]

There've been a lot of requests for a 20 watt 61x Schematic and Layout for the RI by the company I adore in England. I've owned a couple of these myself, including one with the Marshall OEM replacement trannies.

I've drawn up a complete schematic as well as a complete layout, that's 100% accurate to the RI, with the exception of the capcan, which was under the board, and I've scooted it over to a more service able location. I've included all component values and OEM sources.

I used the Mercury transformer set in this layout and schematic because it's the only current direct replacement. I'm not saying you can't use something else (like 18 watt trannys spammed all over the web), I'm just saying that Mercury currently make the only ones that are a drop in replacement. I put the voltages with the OEM replacement tranny set, and when I swap these to the Merc's, I'll post the new voltages as well for comparison.

I've uploaded them to 18watt.com, and sent them off to Larry at Schematic Heaven as well as Blue Guitar.

Here's links for all my good friends here at TGP as well:

20 Watt 61x Schematic
20 Watt 61x Layout

Enjoy!

Mickey C.

PS - I am going on vacation, so I won't be around much in the next week. Don't worry, I am not dropping off the map - just getting some much needed R&R with the wife and kids!

[AL30]

Nice. Thanks

Have a good vacation.

AL

[BBQLS1]

Sweet Mickey!

[Mickey_C]

Hey,

The docs are back up here. I had to take them down at my website, and a couple other forums, when I found out two things:

1. The ones I linked to from here, were unlocked documents.

and not even within 24 hours,

2. Some low life dirt-bag stripped my credits out of the documents and floated them out online, actually stating he had the "right" to do that, so he wouldn't be infringing (which is the opposite of true - the only thing it says you can't do is take away the artist credit).

Anyway, they're back up all over, as all the ones linking to the website are now getting the locked one.

Hopefully somebody out there is getting good use from this stuff! I had torn that amp apart for my Eighteen-Twenty project, and put the doc together thinking some of you DIY'ers might enjoy.

Mickey

[tmac]

Very nice Mickey C thank you.

Any ideas on adding a little bass response to this amp on the bright(er) channel? I love the overall response but would like a little more low end oomph going on. Especially since my grab and go cab is an open back single 12". (I know this amp wasn't designed for that!)

Maybe increase V1 coupling cap from .022 to .047? Would .1 be too much? Or increase PI couplers?

[tmac]

bump

[Mickey_C]

Originally Posted by tmac

Very nice Mickey C thank you.

Any ideas on adding a little bass response to this amp on the bright(er) channel? I love the overall response but would like a little more low end oomph going on. Especially since my grab and go cab is an open back single 12". (I know this amp wasn't designed for that!)

Maybe increase V1 coupling cap from .022 to .047? Would .1 be too much? Or increase PI couplers?

Hey, sorry, I've been up to my neck in building amps lately (and over my head in dealing with parts vendor issues... blech...).

The PI coupling caps might just make it seem more muddy. Have you tried changing the tone stack cap and the mixer bypass cap yet? You might even try increasing those first. If I were to increase the V1 coupler I would lower that cathode bypass cap to something more reasonable first, something like a 25uf 25V. Otherwise, I suspect the cumulative result would be more mud.

(and of course there's always the closed back speaker option - works for me!)

Mickey