Deluxe Reverb based new build

[2pupwonder]

Looking at a new build from scratch. Based on a Fender Deluxe Reverb - AB763 style circuit, and borrowing some layout as well. Basic premise is:
- 1. - eliminating normal channel
- 2. - eliminating the tremolo circuit and tube
- 3. - eliminating the rectifier tube, running it on a full diode rectification. I realize this will change the feel of the amp, but we are aiming for something more super reverb, but little brother, lower wattage. Also, this will boost voltages a bit.
- 4. - packaging it in a princeton reverb chassis and cab size but with a 12" speaker. Scratch building the cab as well, so have the opportunity to make it a bit taller.
- 5. - possibly tweaking some values to make it more suited to OD and distortion pedals to add options.
- 6. - Lar-Mar style master vol
- 7. - presence control
- 8. - mids knob
- 9. - switchable bright cap, maybe adjust the value so bright is not quite as bright.

Couple questions for the community:
- Does my layout look good?
- Does my power supply model look correct? using PSU DII, when doing a full wave rectifier, there are a number of values that need to be halved to make it make sense, however if i run the transformer as source impedance vs voltage, the results are wildly different.

2P

[Stevem]

The sound pressure difference between a Deluxe and a SS is way more due to the SS having 2.8 times more speaker cone area then the wattage difference between the two amps.

[didit]

Hello --

Couple questions for the community:
- Does my layout look good?
- Does my power supply model look correct? using PSU DII, when doing a full wave rectifier, there are a number of values that need to be halved to make it make sense, however if i run the transformer as source impedance vs voltage, the results are wildly different.

I've a similar project albeit presently "mothballed" until my workshop gets set up again. It's going into a Princeton-correct fabricated steel chassis, likely using a prefab PR eyelet board set purchased ages ago.

Unclear what transformers you are considering, and modeling. I've got a set of Hammond "service" parts. I might quibble with a few parameters choices in the PSUD2 screen shot but it's well within the ballpark, but hard to determine what if any advice you're after on that. You might spend a bit. more time on estimating those current taps. Really not keen on 1N4007, though will be using silicon. The UF4007 or other less noisy devices are recommended. I don't recall the part number but I've a stash of 1200V fast diodes that'll get used despite being overengineering.

With the classic chassis as a platform I will be placing a 2x32uF "can" into the hole punched for the rectifier. It'll have a 5W low Ohm resistor to provide a liteweight PI filter. My models suggest ~400VDC at the input to the circuit. Minimizes clutter inside. The original "can" cap hole will get another similar but smaller capacitance unit - TBD. Reverb will be a single tube transformerless option but that's a detail.

No fan of master volumes in small amps, but if pushed would install that pot stack on the rear of your chassis near the power tube sockets. It's a more set and forget for any given session and those long line runs are messy from both chassis clutter and signal integrity.

I would cautiously agree with Steve's comment on Super 4x10" but there are other elements at play in differences between a PR, or DR, and the SR. With my '64 SR and DR set for roughly equal SPL there's more sweet singing charm from the DR and more bite and bark from the SR. A friend has shrunken 2x10" SR and it's got all the bark and bit my 4x10" has, at least at sensible listening levels. I tie that with the combination of output transformer "mass", 6L6 properties, and higher voltages in the preamp. The nominal V2 in a Deluxe has 170V vs 270V in the Super.

No real use for more than one chassis input jack, and will be putting my Dumble-esque PCB FET boost behind that upper hole with a switchable 10K control pot installed.

Best ..

[2pupwonder]

Thanks Didit -

- 1. I have an unpunched chassis - 12ga aluminum Bassman size, so, going to drill my own holes. It's 2" longer and 1" deeper (front to back) than my originally planned PR chassis. Also, making my own board with 1/8" G10 and 1/8" eyelets.
- 2. Transformers are from Pacific Audio Magnetics. Trying out the Red Series for the Deluxe Reverb. The specs look similar to Hammond vintage replacements.
- 3. This build is for someone close to me, they asked for a master on the front panel, so I tried to lay out for the shortest runs from the board the tube socket runs are longer this way tho. MV wiring will be fully shielded to prevent noise. i will be fully testing the amp before getting face plates designed etc... so could move it to the back if it creates issues.
- 4. because I have full freedom to drill the chassis for my needs, planning on separate caps within the chassis as shown in my layout. Do you see any issues with this?
- 5. for the rectifier diodes, that's very interesting about noise from 1N4007. Probably start with them, and see how noisy it is. However, I'll look into getting UF4007s. They are easy to change on the power supply board. I am actually strongly considering going with a tube rec due to the increased voltages, but will test.
- 6. for the power supply model, I've been through the current taps carefully to figure out what they should be, the currents noted have been checked and adjusted several times. looking at the following:
- Node A. - 2x 6v6 plates. 43ma total current - biased at 60% -
- Node B. - 2x 6v6 grids plus (2ma each) 1x 12AT7 reverb driver (both triodes in parallel 1.5ma each). 7ma total
- Node C. Phase inverter. 12AT7 LTPI - 2x triodes @ 1.5ma = 3ma total
- Node D. 2x 12AX7's (2 triodes each)- (stage 1 & 2 triode gain stages, reverb recovery, 3rd gain stage 1.2ma each). 4.4ma total
- Node A has a lot less load than normal for a DR, so i increased the last dropping resistor to reduce the voltage back to normal DR level
- the previous sim I had not saved the final resistor values, so see the new one attached.
- 7. - planning on 1x 12" speaker. Making the cabinet a bit bigger than a PR due to the larger chassis.

My big puzzle is with PSU II - I don't think I am putting in the transformer specs correctly. I am getting wildly different B+ voltages based on RMS V inputs vs Source Impedance.
- Using RMS V - my inputs are 330V and 7% regulation (which returns the 351V close to the unloaded voltage spec) - Getting B+ of 425V
- Using Source impedance - my inputs are 3.61 ohms primary (Black to white) - 58 ohms secondary (red to red) this is 50% of what i measured. - Getting B+ of 460V+
Which is the correct input? 460V seems a bit high compared to what I am reading but is close to 330V * 1.41421. Does anyone have any insight here?

[didit]

Hmmm --

If you've already committed to your planned transformers then running simulation seems somewhat redundant. I'll pass on delving into those specific details except to say past experience using the default RMS model is close enough for rock&roll, or even JAZZ. GIven you're going with a stock clone, unless a tube rectifier is included or some other method of dropping some voltage, you'll be in the upper safe range or perhaps even lower range of overvoltage. I am using a beefy Princeton transformer and will be using 2x32uF with 60-75 Ohm between for the first stage of the power string and B+1 will be off the second capacitor and after the dropping resistor. Standard 4H choke before the screen node, etc ..

You might want to read through this thread from a while back on DR voltages https://ampgarage.com/forum/viewtopic.php?f=8&t=30253. My project's target B+1 is 400VDC with roughly 5V of residual AC ripple.

Your assumptions for current tap values make general sense, but that's without pondering a lot. Uncertain about the last item w. "Node A loading" vs perhaps "Node D". Limited experience is that tweaking dropping resistors for those last few stops on the chain can be interesting tinkering that is recommended. It's also worth considering separating out an independent node for reverb recovery and the "mixing" final stage.

Using a bassman ('60s era?) chassis is cool. No issues spreading filtering around. That's my general preference also when scratch building.

Best .. Ian