Favorite B/F Deluxe Reverb mod?

[jojokeo]

After installion of std US power chord there is no need for the ground switch on back. After telling owner of some possibilities for something there like VVR, NFB switch, presence control, tone stack bypass, or others - what are your suggestions or favorite things you've done or suggest?
Thanks for your thoughts in advance.

[phsyconoodler]

Convert the normal channel into something else.Plexi,Dumble,EF86,5879,Tweed,etc....

[P Batty]

Favorite mod for the ground switch hole? 3-way NFB.  Favorite mod for Deluxe Reverb of any type?  Get as many quality speakers as you can beg borrow or steal.  Try them all. Because you will be running close to maximum output and you only have one speaker, the sound  of the speaker is crucial.  I like a 12" Altec 417, many people like a Weber California with light doping.  Because you only have about 22 watts, you may not need the most heavy duty- a JBL D-120 is too harsh, IMHO, but try a bunch, without any preconceptions.

[jojokeo]

"Convert the normal channel into something else.Plexi,Dumble,EF86,5879,Tweed,etc...."
I couldn't do that, too extreme for the owner to do to his beloved amp...btw, he got it for FREE just simply given to him!!! 

"Favorite mod for the ground switch hole? 3-way NFB."
Yes the ground sw hole and that or a presence control w/ pp pot to be switched out of circuit were the first two ideas I presented to him.
Just wondering how others felt w/ their personal experiences.

[Fresh_Start]

How about a moderate change to the Normal channel?  I put a modified Brown Vibroverb tone stack in, lowered plate voltages, and changed bias of 2nd triode (220K plate/2.7K cathode IIRC).  Then jumpered the 2nd triode of each channel AFTER the coupling caps and before 3.3meg/10pf mixing network.  It's not Tweed, but it's warmer and a little grungier than Blackface.  The owner loves that channel with his Strat.

As far as the former ground switch goes, NFB or presence probably.  How about fixed//cathode bias?  I haven't tried it on an AB763 circuit but it should give him a different tone...

Cheers,

Chip

[chocopower]

To me, NFB switch and tone tweeking in the Normal Channel are the way to go.
In my CLON i had tried:

1.-NFB pot.
2.-Fixed/cathode bias switch. Not very noticiable in my 6L6 amp. Maybe better in a 6V6 one...
3.-5F6A channel using a IRF mosfet. Easy, no a lot invasive and it really works well.
4.-Dissable Tremolo for a gain boost.
5.-Add a dwell pot for the reverb.

[bluesbear]

You could raise the B+ voltage to the PI and pre to SF levels for some actual headroom, something BF Deluxes are sadly lacking. Then, you could separate the cathode resistors on the second preamp tube. Make the vibrato channel 1500 ohm. In the normal channel, leave the 820 ohm. If needed, you could also change the first preamp tube to 820 ohm. Now you have a clean and dirty channel. A better speaker is a really good idea.
Dave

[sluckey]

That switch is in a noisy location. I would not use it for any mods to the preamp section. Mikey Mann liked to put a pentode/triode switch in that hole. Another idea would be to put a fast/slow trem speed switch there.

[jojokeo]

Great ideas you guys, there's a few I hadn't thought of. I'll present the ideas and move forward from there - after all it's not mine so we'll see.

Steve, I was thinking about that "noisy location" too and would run shielded cable for sure if that was ever tried. F-start, I like the idea of the tone stack/load/bias changes for ch #1 too. And BBear I'll consider the headroom changes as he plays a lot of gigs w/ this and he may need that. As for speaker, he already changed that to a V-30 and likes it so he'll likely want to keep that in. Choco, nice ideas - could you point me to or show what mosfet mod you're talking about?

Thanks again you guys.

[chocopower]

hi,
I take the idea from:

http://www.geofex.com/Article_Folders/mosfet_folly/mosfetfolly.htm

and make it in that way...

https://picasaweb.google.com/davidageitosfuentes/GuyatoneGa1050#

[LooseChange]

On that JTM mod... Forget the MOSFET. It provides no gain and IMO no advantages.
Just run the tone stack off the plate of the second gain stage. You will be pleased.

[chocopower]

On that JTM mod... Forget the MOSFET. It provides no gain and IMO no advantages.
Just run the tone stack off the plate of the second gain stage. You will be pleased.

just for learn. The cero gain is the usual for a tube cathode follower too, isn´t?

[fiftynine]

A mid pot I find. Not just to add a bit of gain but also to give a bit of extra scoop. Big iron has transformed my builds as well. The bass keeps in check for longer. 200 plus volts at the pre amp and PI sounds good to my ears. I have a build that punches like a vibrolux on 7 but still does the BFDR thing at 10, mid pot maxed. Nice.

[samato]

How about a way to keep the low end from farting out so much at high volume?  Is that just a speaker thing or are there some circuit tweaks to help with this that wouldn't change the overall character?

[LooseChange]

Cut those cathode caps (22uf) on the preamp back to 10uf or 5uf. Stops the "woofyness" too.

[sluckey]

In addition to what LC said, change the PI output coupling caps to 0.047µF.

[samato]

Just so I'm clear, on this diagram it would be making C1 & C2 10uf or 5uf and/or C9 & C10 .047uf right?

http://www.el34world.com/Forum/index.php?action=dlattach;topic=9891.0;attach=17952;image