[Alan Small]

glad you are making progress.
the feedback loop may be moot now: some enjoy a switch to close or open the loop and call it a "tweed" switch

 

[_Knighthawk_]

glad you are making progress.
the feedback loop may be moot now: some enjoy a switch to close or open the loop and call it a "tweed" switch

Interesting. I need to know all about this now. I will definitely research this and give it a shot. Will let you know how it turns out.

 

[_Knighthawk_]

Not sure if anyone is interested or not but just in case:

Sharing my parts list for this build...

Item	Brand/Source	COST	SOURCE
Power Transformer	Hammond 291BX	$163.99​	Hammond 291BX - Power Transformer UPGRADE UPGRADE for (Deluxe, 5A3, 5B3, 5C3, 6G3, AB763) (Deluxe Reverb, A1172, A1270, AA763, AB763, AB868, Blackface, Silverface, W/Volume Boost) Tweed Tremolux UPGRADE to Fender part number 125P23D & 041316 nextgenguitars.ca
Output Transformer	Hammond 1760H	$93.99​	Hammond 1760H - Output Transformer UPGRADE - 4/8/16 OHM Added 4/8/16 OHM secondary. nextgenguitars.ca
Choke	Hammond 194A - Choke - 4H, 50mA	$31.99​	Hammond 194A - Choke - 4H, 50mA
Reverb Driver	Hammond 1750A - Output Transformer - 25K, 8 OHM, SE, 3.5W	$46.99​	Hammond 1750A - Output Transformer - 25K, 8 OHM, SE, 3.5W Replacement for Reverb Driver Equivalent to manufacturer part number #125A20B & #022921 nextgenguitars.ca
Cabinet	Veteran Guitars	$400.00​	Veteran Guitar Cabinets (see Facebook)
Tubes	Premium Package	$445.70​	Fender Deluxe Reverb (AA763 and AB763) - Premium Package This is a premium retube kit for Blackface and Silverface Fender Deluxe Reverb (AA763 and AB763) tube amps. Note, this is for the versions AA763 and AB763 using 5AR4 / GZ34 rectifier tube types. www.thetubestore.com
Chassis +	Boards, Doghouse Pan, Faceplates, Footswitch, Knobbies	$450.00​	MOJO - includes $75 shipping
Reverb Tank	MOD 4AB3C1B	$57.00​	Nextgen
Reverb Tank Bag	17"	$20.99​	Nextgen
RCA Jacks		$10.19​	Shielded RCA Cable - Stereo Right Angle (3 feet) Right angle RCA cables for Reverb Tanks and other electronic devices. nextgenguitars.ca
Legend 1258	Eminence (client's choice of speaker)	$166.39​	Eminence 12" Guitar Speakers - Canada Eminence 12" guitar speakers for building or repairing amps and speaker cabinets. nextgenguitars.ca
Components	Passive components and hardware-NextGen	$355.00​	(Pots, jacks, switches, tube sockets, lamp, capacitors, etc.)

A big shout out to the folks at NextGen Guitars! They're a Canadian outfit located in Ottawa (Nepean). Reasonably priced components, outstanding customer service (I think the owner, Jonathan Beals is a GC member). I also have to acknowledge and pass along kudos to Derrick Bell at Veteran Guitar cabs (some of you probably know Derrick) for his great work on the blackface cabs he builds for me. He is kind enough not to chuckle at me when I ask him about my crazy design ideas.

 

[Richard Gear]

Update: Breakthrough! And it WAS something simple!

The volume surge in the volume channel was caused by a bad tone cap. On a whim (to rule it out), I removed it and f'ing voila!!! Volume surge gone!

It's pretty funny that the $3000 amp build can get side-swiped by the $3 capacitor!

Anyway, so, now to get these voltages under control and tweak the ground scheme to kill some of this blasted Deluxe Reverb hum. I have had success with this last on my Vibroverb builds (same circuit) so it's just a matter of arm wrestling and little tweaks to get this right. That said, I'm all ears if anyone has any ground scheme suggestions.

You can see what I have done here: power amp ground, preamp ground bus, reverb ground to reverb pedal ground lug, etc. Always open to new ideas.

Robinette offers some helpful reverb quiet ideas borrowing some of the innovations from the silver face era. My first suggestion is sticking a 12U7 in the reverb driver for starters.

I’ve also thought about a kill switch for the reverb and tremolo Via a push pull pot.

One of the best sounding off the shelf amps that I’ve ever had was the ‘64 handwired Deluxe Reverb. I sold it after a year of listening to the hiss coming from it. I figured I didn’t want to poke around it too much as I’d seen dozens and dozens of people complaining about the issue and how they eventually all returned the amp to sweet water after getting the “hiss is inherent” from Fender.

After building a few very silent amps, I have to say, the least silent is a Princeton reverb build. It’s still quieter than the Deluxe NR. I’m wondering what would happen if one were to split V1 and 2’s shared cathode and convert the 820 to 1.5k and add an i dependant 1.5k to V1’s cathode. Either way, it’s a part of the fun.

 

[_Knighthawk_]

After building a few very silent amps, I have to say, the least silent is a Princeton reverb build. It’s still quieter than the Deluxe NR. I’m wondering what would happen if one were to split V1 and 2’s shared cathode and convert the 820 to 1.5k and add an i dependant 1.5k to V1’s cathode. Either way, it’s a part of the fun.

Interesting. One of my next projects is a Princeton. I'd love to hear all about it if you ever go wandering down this path!

 

[Richard Gear]

Interesting. One of my next projects is a Princeton. I'd love to hear all about it if you ever go wandering down this path!

The Princeton is a son of a bitch to build. But you’ve already built the Deluxe, so it will likely feel like a slightly easier build in comparison.

I also chose to use resistors and bypass caps that are 4 times the needed size on the Princeton. So I did it to myself. But it is a sweet little amp. If you really want to blow your budget out of the water, check out “soursound” transformers. I’m likely going to fire a set into my 5E3 at some point. I may try their output transformer in the Princeton. Hammond makes quality units, but I think the owner soursound is a little bit autistic and has more or less lost his mind and became a rocket scientist in order to recreate super accurate remakes of classic Fender output transformers. Worth checking out.

 

[_Knighthawk_]

So, I'm still having issues with voltage.

I'm seeing B+2 voltage of 490VDC coming out of the doghouse and going to the reverb driver. This is definitely high since the 12AT7 at V3 is expecting to see ~410V. Any ideas why my B+2 is so high?

Incidentally, I've got 490VDC going to the plates in the power tubes (V6 and V7).

I'm at a loss here. Is it possible I have blown 10K resistors? A leaking or open cap? Any ideas?

EDIT: My mains are stupid high (126VAC)..

 

[Paul Running]

Any ideas why my B+2 is so high?

what's the PN for the power transformer?
I ask because I want to determine the DCV.
Sorry, I did not check your PL above...it does say 291BX?

 

[Paul Running]

EDIT: My mains are stupid high (126VAC)..

That's common in my neck of the woods.

 

[Paul Running]

At 126VAC, the 291BX will produce 489VDC, with no load.
126/120 × 330 × 1.414

 

[Paul Running]

The circuit is an original AB763 circuit?

 

[_Knighthawk_]

The circuit is an original AB763 circuit?

Yes. Yes and yes.

It is almost exactly 489 VDC.

 

[Paul Running]

Is it possible I have blown 10K resistors?

What is the voltages dropped across the 10KΩ resistors? (to determine the current draw of the preamp circuitry)

 

[_Knighthawk_]

Voltage drops: R1 60V and R2 100V.

 

[Paul Running]

Use Ohm's law to determine: Voltage B - Voltage C / 10,000.
and the same for Voltage C - Voltage D / 10,000.

 

[_Knighthawk_]

The math is the easy part (at least for me). The problem is that I don't know where exactly to measure Va, Vb and Vc, Vd.

 

[Paul Running]

Okay, I'll highlight the points on the layout drawing.

 

[_Knighthawk_]

Hold up. If I am doing this right, my readings are:

A=484V
B= 484V
C=380V
D=315V

Which would provide answers to your questions:

Vb - Vc / 10000 = 0.0104
and
Vc-Vd / 10 000 = 0.0065

And I am sure this must mean something. Hints as to what?

 

[_Knighthawk_]

I confess that I don't understand why we bother running wires in and out of the doghouse for B+2 since we could pull exactly the same B+2 voltage from the mainboard off of the choke. It seems like a silly exercise to me since it's B+2 no matter where you get it from. Is it to prevent interference on the long run to the V3 and V5 plates?

EDIT: Wife wants me to break for dinner. I didn't even realize it was that time!

 

[Paul Running]

Is there any functional issues with the amp, presently?