Hoffman Single Channel AB763

[purpletele]

If I read your tangled quote correctly: the problem is in the reverb recovery stage.

PRR,

Thanks for the bread crumb trail.  The return jack was missing a plastic sleeve and therefore I was grounding out the signal.  All fixed and sounding really nice!!

[bnwitt]

Ah tenacity.  Always pays off.  Way to hang in there Brian.

[purpletele]

I had planned on a PPIMV for this upgraded Deluxe Reverb.

The amp sounds so nice right now but as anticipated, it is loud. 

Am I going to spoil the sweetness of this amp by adding the MV?

Is it worth trying or do I make this amp a performance amp only?

[purpletele]

Luckey Deluxe Update and New Question

I have been enjoying my Deluxe Reverb very much, it sounds exactly as I hoped.

I decided to not install a Master Volume, however, I would like to try a Mojotone FX's Loop.

Advice Needed:  I had anticipated utilizing a Pot for the level on the send and return on the loop but I am limited on space so I jumped the Pot connections and made the circuit a fixed level.

The instructions from Mojotone are weak at best and I would like to verify my logic.


1. I was going to insert the Send signal into the 250 pF cap in the tone stack feeding the Treble Pot

2. I was going to place the Return route into the 1 Meg resistor of the PI.

3. I was going to pick up B+ from node D

I am a bit parnoid about damaging this circuit via a boner move.  Do the connections as desribed make sense for entry and exit points?  I have attached a schematic and layout for reference.


Thank you,

BV

[sluckey]

Here's the whole schematic...

     http://el34world.com/Hoffman/files/Hoffman_AB763_1.pdf

1. I was going to insert the Send signal into the 250 pF cap in the tone stack feeding the Treble Pot  NO

2. I was going to place the Return route into the 1 Meg resistor of the PI.  NO

3. I was going to pick up B+ from node D  Probably. May need to add another RC filter stage.

The loop would normally go between the preamp output (page 3) and the PI input (page 4). Is this the FX Loop?

http://www.mojotone.com/Accessories_x/Attenuators_x/Mojotone-Discrete-Hi-Voltage-Series-Effects-Loop-for-Vacuum-Tube-Amplifiers

[purpletele]

Here's the whole schematic...

     http://el34world.com/Hoffman/files/Hoffman_AB763_1.pdf

1. I was going to insert the Send signal into the 250 pF cap in the tone stack feeding the Treble Pot  NO

2. I was going to place the Return route into the 1 Meg resistor of the PI.  NO

3. I was going to pick up B+ from node D  Probably. May need to add another RC filter stage.

The loop would normally go between the preamp output (page 3) and the PI input (page 4). Is this the FX Loop?

http://www.mojotone.com/Accessories_x/Attenuators_x/Mojotone-Discrete-Hi-Voltage-Series-Effects-Loop-for-Vacuum-Tube-Amplifiers

That's the FX loop that I bought and plan on using.

[sluckey]

This is how I would connect that FX board to the Hoffman board...

[purpletele]

This is how I would connect that FX board to the Hoffman board...

Thank you Steve!  I'll give it a shot.

Update
Oh dear, remove jumper!!  I wonder if it is worth the trouble?

Maybe I design it into my 2nd Deluxe Combo.


Update Again

Steve, thank you for the detail.  I think I am going to hold off on that mod for right now.  I would be upset at myself if I created a mess.

BV

[sluckey]

You gonna let a little jumper whip you? Here's an alternative. Unsolder the .001 cap bottom lead as seen in the pic. Stand the cap up and attach the FX OUT wire to the dangling end of the cap. Secure the cap lead so it can't move around and short to anything else.

If you do decide to remove the jumper and for some reason don't care for the fx loop, just remove the loop and replace the jumper on the TOP SIDE OF THE BOARD.

[purpletele]

You gonna let a little jumper whip you? Here's an alternative. Unsolder the .001 cap bottom lead as seen in the pic. Stand the cap up and attach the FX OUT wire to the dangling end of the cap. Secure the cap lead so it can't move around and short to anything else.

If you do decide to remove the jumper and for some reason don't care for the fx loop, just remove the loop and replace the jumper on the TOP SIDE OF THE BOARD.

Ok, thanks for the push.

I better get a good video demo of the amp prior to this operation.

Thanks,

BV

[purpletele]

You gonna let a little jumper whip you? Here's an alternative. Unsolder the .001 cap bottom lead as seen in the pic. Stand the cap up and attach the FX OUT wire to the dangling end of the cap. Secure the cap lead so it can't move around and short to anything else.

If you do decide to remove the jumper and for some reason don't care for the fx loop, just remove the loop and replace the jumper on the TOP SIDE OF THE BOARD.

Steve,

I cowboyed up and installed the FX loop as detailed and it seems to work quite well.  I will plan for the variable Pots next time.

The FX loop seems a tad noisy.  I'm sure there are quite a few reasons for that, I did use the cool Belden RG 188 Shielded wire. It's not noisy enough to warrant any surgery.

I think it is an asset to the amp, I'm glad I did the mod. 

Thank you Steve for the nice detail and encouragement.

This amp is just about complete.

BV

[purpletele]

A couple of clips of the Luckey Deluxe Reverb

[sluckey]

Sounds very Fendery. Nice playing too. So, what are your thoughts about the DR as compared to the PR? Do you prefer one over the other?

[purpletele]

Sounds very Fendery. Nice playing too. So, what are your thoughts about the DR as compared to the PR? Do you prefer one over the other?

Good question on the comparison of the two amps.

I like the articulation of the Princeton for comping tunes by myself, the amp has the power to really sing nicel.

The DR is definitely a do it all workhorse of an amp.  I can see a long useful life of that amp for personal use.  The way that amp is set up with the upgraded transformers and the really nice speakers lends itself to be played with some volume to get it to breath.  I like its ability to produce nice loud and pure chords at performance volumes.

I have played reissue model DR and they don’t compare to the power and feel of this circuit.

I have concluded that I like each amp for the purpose they were originally designed for!

I am very impressed and quite pleased with the whole building experience for these two amps, thanks again for the work and assistance that you and the rest of the mad scientists provide.

Note: I sold both of my Princeton’s to some friends and they are getting played quite a bit without issue, so that’s another cool factor. 

I have parts for one more DR to complete, then i’m on to a 50 Watt Plexi

BV

[purpletele]

Luckey Deluxe Story

My friend Adam Block has been using the Deluxe with a open back 1 x12 with Cream Alnico, it sounds fantastic, but we hadn't tried it live until last night.

Adam was the guitarist hosting a Blues jam at the Torch in Sacto.  I was coming down to film and see how it sounds and I was pleasantly surprised at the tone.  The place was jammed with a retirement party. 

The singer harmonica player was bent over at about 90 degrees and wailing.  Mick Martin joined in with the band and didn't get anything on film, but it was cool.

He is a nice guy but man I feel for him with the scoliosis or whatever ails him.