Friedman Naked Amp schematic?

[megatrav]

Hi,

I've been searching and reading and trying to find the schematic for the Naked Amp by Friedman. Can anyone send a link or post an image?

Thanks!

[frankdrebin]

its very much like the Naylor super drive,power amp more like a classic Marshall

[Lauri]

You can usually find schematics for Friedman amps at http://slocloneforums.com . People there seem to be obsessed with Friedman.

[megatrav]

Thank you!

[megatrav]

I’m looking at this schematic and I don’t see where the clean channel portion is. Am I missing something?

[Gainzilla]

The schematics above are for the main circuit in general, and a Marshall that could be modded to Naked spec, not a full schematic of the "Friedman" Naked amp. I use quotes because this is not his circuit, but rather a clone he made of the Naylor Superdrive (the reason he called it Naked. Tip of the cap to the original amp).

Couple thoughts on this... Firstly, the SuperDrive amps are capable of gorgeous cleans just by rolling back the guitar volume. You could probably build the Naked exactly as the schematic shows and be able to get clean's you'd be happy with. If you did need a dedicated clean, you might just make a switchable 1M pot that bypasses the 2nd stage (bit like a plexi). You would need a relay or similar to switch between that and the existing overdrive gain control. You would probably need a second switchable master volume.

One other thought. If you do make a separate clean control and find the first stage to be a little hot, you could use a split-anode arrangement, and build a separate coupling circuit to take you to the new pot. The main existing circuit would be build as-designed, and the new coupling circuit would be taken from the junction of the two anode resistors.

[megatrav]

Thanks for the information.

I have seen a few different versions of the Friedman Naked amp. I'm sure he has implemented the split-anode designed as well as separate clean channel with volume, bass, and treble with a bright switch.

Do you have any schematic examples of a split-anode arrangement?

I understand how it would work in theory but it helps to see it laid out as a starting point.

[xenrelic]

The Naked MK1 amp is different from the long form schematic posted here. I'm assuming that is a schematic of a variant of the OD channel that someone made up.

These are the specs you need to change for MK1.

Power filtering:
C1 & C22 16uF 500v

Preamp:
Add .01uF from ground of input to chassis
Delete C19
Add 10k to input grid of stage 1
C32 .001uF
100k added between GAIN_2 1 and GND.
R25 1M
Add 10k to input grid of stage 2
Delete R36
Move BITE 2 SW between C29 and GND, then add a 100k resistor from the GND side of the capacitor to GND as this will remove switching pop. The MK1 doesn't have the bit switch installed and just has C29 in parallel with R35 with no R36.
Delete R49
C24 .0022uF
C4 replace with jumper
R46 Delete
R1 820R

EQ:
C25 220pF
R48 27k

There should be a tube buffered FX Loop after the treble pot.
FX Loop stages are biased at 10k with 220k plate resistors
.68uF coupler from cathode of first loop stage to send
Return has a 560k with 100pF to GND before the input grid of loop stage 2
.022uf from loop stage 2 plate to 1MA master volume with 1M resistor in parallel from pot input to GND.
Output of master volume gets sent to C30

Phase inverter:
C17 250pF
C10 .022uF
R45 10k
C38 .0047uF
Presence pot 25k.
R26 Jumper
Delete Depth Pot
C35 .001uF goes to SPKR Jack Tip

Bias splitters:
R43 100k
R47 100k


Preamp power nodes:
Delete R22
10k from PI node to feed Stage 1 and 2
10k from PI node to feed Stages 3 and 4
Loop Stages fed by PI node

Screen Node Power Filter Balancing Resistors:
R39 68k
R41 68k

Choke 3H 158 ohms (Mercury Magnetics 2611)

Output transformer Marshall 100W type
Power transformer:
189v-0-189v no load HV Secondary
187v-0-187v with load HV Secondary
7.5v-0-7.5v for 15vac to 12v regulator circuit for relay switching.
3.15v-0-3.15v heater

Heater supply center tap is DC lifted with the PI power node.
100k from PI node to 10k
Center Tap of Heater goes to 100k-10k junction
10k to GND
.047uF 630v capacitor in parallel with 10k


The stock Naked MK1 that Metroamp built for Friedman has about 398v at the phase inverter power node with the EL34's biased at around 70%.

The best tones I got from the Naked MK1 I've played was when the PI node voltage was adjusted down to about 330v Super Lead version and 370v Naylor version.

370v feels tighter and sounds more saturated, closer to the Mer De Noms record and the real Naylor SD60.
330v is even more saturated, but a little looser/browner feeling like the mod was performed on a Super Lead head with both 10k voltage drop resistors in place before the PI power Node
Stock 398v/400v sounds rounder and less saturated than the others. Not a bad tone, but I definitely preferred the lower voltages more.

I also tried the 345v at the PI node mentioned in the first schematic posted, but it didn't sound right to me. It was sort of in between the 330v and 370v sound and it was my least favorite. It seemed fuzzier and out focus to me than 370v, but it didn't have the saturation of the 330v. It wasn't bad, but left me wanting to go back to 330v or 370v.

[Colossal]

Phase inverter:
C17 250pF
C10 .022uF
R45 10k
C38 .0047uF
Presence pot 25k.
R26 Jumper
Delete Depth Pot
C35 .001uF goes to SPKR Jack Tip

Xenrelic,

Thanks for posting that. Billy Howerdel has killer tone. So, no feedback resistor? Just the capacitive divider 1n->10n/4k7? Do you know if this is on the 4R tap, as shown?

Thanks.

[xenrelic]

Xenrelic,

Thanks for posting that. Billy Howerdel has killer tone. So, no feedback resistor? Just the capacitive divider 1n->10n/4k7? Do you know if this is on the 4R tap, as shown?

Thanks.

No feedback resistor, just the 10k/4.7nF to GND with the 1nF straight to the speaker jack tip. It's not connected to a particular output tap. Billy uses his with a Marshall 1960A 16ohm cab loaded with Marshall Vintage speakers, so he's most likely connected to the 16ohm tap with his modern rig. I think earlier in his career he used two VHT 16ohm cabs that were loaded with Vintage 30's in one cab and 25watt Greenbacks M's in the other and that would have been with the 8ohm tap. On smaller TV performances he's seen using only one Marshall 1960A cab with the Marshall Vintage speakers.

[megatrav]

The Naked MK1 amp is different from the long form schematic posted here. I'm assuming that is a schematic of a variant of the OD channel that someone made up.

These are the specs you need to change for MK1.

Power filtering:
C1 & C22 16uF 500v

Preamp:
Add .01uF from ground of input to chassis
Delete C19
Add 10k to input grid of stage 1
C32 .001uF
100k added between GAIN_2 1 and GND.
R25 1M
Add 10k to input grid of stage 2
Delete R36
Move BITE 2 SW between C29 and GND, then add a 100k resistor from the GND side of the capacitor to GND as this will remove switching pop. The MK1 doesn't have the bit switch installed and just has C29 in parallel with R35 with no R36.
Delete R49
C24 .0022uF
C4 replace with jumper
R46 Delete
R1 820R

EQ:
C25 220pF
R48 27k

There should be a tube buffered FX Loop after the treble pot.
FX Loop stages are biased at 10k with 220k plate resistors
.68uF coupler from cathode of first loop stage to send
Return has a 560k with 100pF to GND before the input grid of loop stage 2
.022uf from loop stage 2 plate to 1MA master volume with 1M resistor in parallel from pot input to GND.
Output of master volume gets sent to C30

Phase inverter:
C17 250pF
C10 .022uF
R45 10k
C38 .0047uF
Presence pot 25k.
R26 Jumper
Delete Depth Pot
C35 .001uF goes to SPKR Jack Tip

Bias splitters:
R43 100k
R47 100k


Preamp power nodes:
Delete R22
10k from PI node to feed Stage 1 and 2
10k from PI node to feed Stages 3 and 4
Loop Stages fed by PI node

Screen Node Power Filter Balancing Resistors:
R39 68k
R41 68k

Choke 3H 158 ohms (Mercury Magnetics 2611)

Output transformer Marshall 100W type
Power transformer:
189v-0-189v no load HV Secondary
187v-0-187v with load HV Secondary
7.5v-0-7.5v for 15vac to 12v regulator circuit for relay switching.
3.15v-0-3.15v heater

Heater supply center tap is DC lifted with the PI power node.
100k from PI node to 10k
Center Tap of Heater goes to 100k-10k junction
10k to GND
.047uF 630v capacitor in parallel with 10k


The stock Naked MK1 that Metroamp built for Friedman has about 398v at the phase inverter power node with the EL34's biased at around 70%.

The best tones I got from the Naked MK1 I've played was when the PI node voltage was adjusted down to about 330v Super Lead version and 370v Naylor version.

370v feels tighter and sounds more saturated, closer to the Mer De Noms record and the real Naylor SD60.
330v is even more saturated, but a little looser/browner feeling like the mod was performed on a Super Lead head with both 10k voltage drop resistors in place before the PI power Node
Stock 398v/400v sounds rounder and less saturated than the others. Not a bad tone, but I definitely preferred the lower voltages more.

I also tried the 345v at the PI node mentioned in the first schematic posted, but it didn't sound right to me. It was sort of in between the 330v and 370v sound and it was my least favorite. It seemed fuzzier and out focus to me than 370v, but it didn't have the saturation of the 330v. It wasn't bad, but left me wanting to go back to 330v or 370v.

Thank you very much!