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Deluxe Reverb Plus V2 - and the hunt for 5e3 tone
Deluxe Reverb Plus V2 - and the hunt for 5e3 tone
The story begins with a friend loaning me a 5e3 Tweed Deluxe clone. A very nice amp. I'd never really appreciated the 5e3 - the controls were too weird for me to zone in on in the short spurts I had to play one. This loaner amp was with me for a whole summer and within a week or so I had the controls figured out and just played it for sheer joy.
The story begins with a friend loaning me a 5e3 Tweed Deluxe clone. A very nice amp. I'd never really appreciated the 5e3 - the controls were too weird for me to zone in on in the short spurts I had to play one. This loaner amp was with me for a whole summer and within a week or so I had the controls figured out and just played it for sheer joy.
The tone is so full and so different from BF Fender tones. It's sings so sweetly, yet it bites and growls when you want to. I know it's been said many times, but it's so responsive, it's just a joy to play. Anyway... it got me looking at the Deluxe Reverb Plus (DRP) I built some years ago and wondering why it didn't have that same tone quality.
The tone is so full and so different from BF Fender tones. It's sings so sweetly, yet it bites and growls when you want to. I know it's been said many times, but it's so responsive, it's just a joy to play. Anyway... it got me looking at the Deluxe Reverb Plus (DRP) I built some years ago and wondering why it didn't have that same tone quality.
A Deluxe Reverb (and the DRP) have far more controls to shape tone, but the tone settings just produce variations of the classic BF scoop tone. It's great at what it does, but why can't it also do the 5e3 thing? What is it that makes these two amps sound so different?
A Deluxe Reverb (and the DRP) have far more controls to shape tone, but the tone settings just produce variations of the classic BF scoop tone. It's great at what it does, but why can't it also do the 5e3 thing? What is it that makes these two amps sound so different?
Answering that question would reveal whether it's possible to get that tone from a DR without completely rebuilding it or embedding a complete 5e3 in the DR cabinet. They both have a 6V6 push pull output stage, although the 5e3 uses cathode bias while the DR has fixed bias. The phase inverters are cathodyne for the 5e3 and long-tail for the DR. Of course the tone stacks are completely different too.
Answering that question would reveal whether it's possible to get that tone from a DR without completely rebuilding it or embedding a complete 5e3 in the DR cabinet. They both have a 6V6 push pull output stage, although the 5e3 uses cathode bias while the DR has fixed bias. The phase inverters are cathodyne for the 5e3 and long-tail for the DR. Of course the tone stacks are completely different too.
It's tempting to stop there since the differences are great and there is little circuitry common to both amps. I thought about it for a while and finally, when I had a chunk of available time I decided that even if I couldn't get the 5e3 tone from the DRP, I just wanted to know what circuit differences are key to making the tone difference.
It's tempting to stop there since the differences are great and there is little circuitry common to both amps. I thought about it for a while and finally, when I had a chunk of available time I decided that even if I couldn't get the 5e3 tone from the DRP, I just wanted to know what circuit differences are key to making the tone difference.
My initial test was the output stage since I wanted to add cathode bias to the DRP as a switch option anyway. The DRP had a switch on the front panel (see that article for details) that switched between bias tremolo and opto tremolo. It seemed ideal to widen that switch to include two more poles for bias switching.
My initial test was the output stage since I wanted to add cathode bias to the DRP as a switch option anyway. The DRP had a switch on the front panel (see that article for details) that switched between bias tremolo and opto tremolo. It seemed ideal to widen that switch to include two more poles for bias switching.
Bias tremolo makes sense for fixed bias, while opto tremolo is a good option for cathode bias. Since both tremolo systems were already in the amp, the cathode bias switching was easy to add. There are many sources that show how to switch between fixed and cathode bias so I'll skip the details. The schematic below shows the circuit I used. I tried bypassed and unbypassed cathode bias, opting in the end to leave it bypassed.
Bias tremolo makes sense for fixed bias, while opto tremolo is a good option for cathode bias. Since both tremolo systems were already in the amp, the cathode bias switching was easy to add. There are many sources that show how to switch between fixed and cathode bias so I'll skip the details. The schematic below shows the circuit I used. I tried bypassed and unbypassed cathode bias, opting in the end to leave it bypassed.
While the amp breaks up and feels a bit different at high volumes, neither of the cathode bias options does much to make the DRP sound like a 5e3. So while the bias circuit may have a minor impact, it's not the big difference-maker I was looking for. Of course the OT impedances in the DR and 5e3 are also different but from all I've read and heard, it's not a major tone issue so I'll leave that experiment for another day.
While the amp breaks up and feels a bit different at high volumes, neither of the cathode bias options does much to make the DRP sound like a 5e3. So while the bias circuit may have a minor impact, it's not the big difference-maker I was looking for. Of course the OT impedances in the DR and 5e3 are also different but from all I've read and heard, it's not a major tone issue so I'll leave that experiment for another day.
The other circuit candidates could be harder to test, so I considered my options. The phase inverters are different and they'll break up differently in overdrive, but the amps sound different even a low volumes, so it's hard to see how the PIs could be responsible for that. That left the tone stacks. Surprisingly, I could not find any curves on the web showing the range of the 5e3 tone stack. I may have missed something, but it wasn't hard to do some SPICE simulations and come up with the following curves.
The other circuit candidates could be harder to test, so I considered my options. The phase inverters are different and they'll break up differently in overdrive, but the amps sound different even a low volumes, so it's hard to see how the PIs could be responsible for that. That left the tone stacks. Surprisingly, I could not find any curves on the web showing the range of the 5e3 tone stack. I may have missed something, but it wasn't hard to do some SPICE simulations and come up with the following curves.
The 5 solid lines show Bright Channel responses for tone settings of .6, .7, .8, .9, and max, with both volume controls set at .5. They show a shallow scoop at low freq's (~150-300Hz) and a gradually rising response at higher frequencies. I think people intuit what the 5e3 controls do, but SPICE curves leave no doubt. The increase at high frequencies is only 2-6 db and the dip is very shallow and at much lower freq's than the BF scoop.
The 5 solid lines show Bright Channel responses for tone settings of .6, .7, .8, .9, and max, with both volume controls set at .5. They show a shallow scoop at low freq's (~150-300Hz) and a gradually rising response at higher frequencies. I think people intuit what the 5e3 controls do, but SPICE curves leave no doubt. The increase at high frequencies is only 2-6 db and the dip is very shallow and at much lower freq's than the BF scoop.
Using SPICE I tried to adjust a stock DR tone stack to create a response similar to the 5e3 curves, but it's just not possible. This is why the DR just won't sound like a 5e3. The DR tone controls just can't achieve anything close to the 5e3 response curve. This is probably not big news to many of you, but it is hard evidence and a possible answer to my question.
Using SPICE I tried to adjust a stock DR tone stack to create a response similar to the 5e3 curves, but it's just not possible. This is why the DR just won't sound like a 5e3. The DR tone controls just can't achieve anything close to the 5e3 response curve. This is probably not big news to many of you, but it is hard evidence and a possible answer to my question.
If the DR tone stack could achieve that 5e3 curve, would it sound and play like a 5e3? How to best test that? I could build the 5e3 tone stack in my amp, but I'd rather not rip up my DRP. It's probably the most complex hand-wired amp I've built, so it's hard to modify and I really don't want to use it as a guinea pig.
If the DR tone stack could achieve that 5e3 curve, would it sound and play like a 5e3? How to best test that? I could build the 5e3 tone stack in my amp, but I'd rather not rip up my DRP. It's probably the most complex hand-wired amp I've built, so it's hard to modify and I really don't want to use it as a guinea pig.
Fortunately, the ChA preamp (the cascode channel) in the DRP has a switchable scoop frequency. By adding a low-freq scoop circuit to my SPICE simulation I soon found a range of settings that produced curves similar to the 5e3 curves. I set the switches and tone pots on the real DRP based on the simulation and VOILA - beautiful 5e3 tones pouring out of the DRP amp.
Fortunately, the ChA preamp (the cascode channel) in the DRP has a switchable scoop frequency. By adding a low-freq scoop circuit to my SPICE simulation I soon found a range of settings that produced curves similar to the 5e3 curves. I set the switches and tone pots on the real DRP based on the simulation and VOILA - beautiful 5e3 tones pouring out of the DRP amp.
Since the range of ChA settings is wider than those available in the 5e3, the DRP offers very useful control over the bass levels. A range of settings give the distinctive mid range body and plucky string character that the 5e3 has so it seems that most of the 5e3 character flows from its tone stack curves.
Since the range of ChA settings is wider than those available in the 5e3, the DRP offers very useful control over the bass levels. A range of settings give the distinctive mid range body and plucky string character that the 5e3 has so it seems that most of the 5e3 character flows from its tone stack curves.
The curves below are the response of ChA in FAT mode with the low-freq scoop setting. Treble range is .4-.5 (in 3 steps), and Bass range is .35-.45 (in 3 steps). The variations are smooth and all produce a distinctly 5e3 tone quality. Many settings produce less pronounced bass, which is good IMO, and further knob twisting creates interesting variations too.
The curves below are the response of ChA in FAT mode with the low-freq scoop setting. Treble range is .4-.5 (in 3 steps), and Bass range is .35-.45 (in 3 steps). The variations are smooth and all produce a distinctly 5e3 tone quality. Many settings produce less pronounced bass, which is good IMO, and further knob twisting creates interesting variations too.
So, the moral of the story is that 5e3 and BF tones can live in the same amp if the tone stack has the range needed to cover both curve sets. A related moral is that there is a big payoff for using somewhat complex tone stacks, such as the one in the DRP. Investing in some resistors, caps, and switches gives a wider tone stack range that pays off in surprising ways. I've had the Deluxe Plus for many years and I just found this surprise in there.
So, the moral of the story is that 5e3 and BF tones can live in the same amp if the tone stack has the range needed to cover both curve sets. A related moral is that there is a big payoff for using somewhat complex tone stacks, such as the one in the DRP. Investing in some resistors, caps, and switches gives a wider tone stack range that pays off in surprising ways. I've had the Deluxe Plus for many years and I just found this surprise in there.
Lastly, in pursuing this 5e3 project I revisited several of the DRP circuits and made some changes that I think are improvements. So here is the DRP V2 schematic with a list of summary changes. Most of the changes make the amp tone cleaner and less bright - even the FAT mode is cleaner and now has a mild mid-boost. My tastes just lean that way now.
Lastly, in pursuing this 5e3 project I revisited several of the DRP circuits and made some changes that I think are improvements. So here is the DRP V2 schematic with a list of summary changes. Most of the changes make the amp tone cleaner and less bright - even the FAT mode is cleaner and now has a mild mid-boost. My tastes just lean that way now.
- Add 2 x 5w cathode bias resistors (bypassed with 47uf/50v) 220 and 270 in series with 4.7K trim resistor in parallel
- Add 2 x 5w cathode bias resistors (bypassed with 47uf/50v) 220 and 270 in series with 4.7K trim resistor in parallel
- bias to 20ma/7.2w (fixed) and 30ma/10w (cathode)
- bias to 20ma/7.2w (fixed) and 30ma/10w (cathode)
- Use 4pdt at trem switch position for sync'd bias/trem switching
- Use 4pdt at trem switch position for sync'd bias/trem switching
- Opto trem+cathode bias or Bias trem+fixed bias
- Opto trem+cathode bias or Bias trem+fixed bias
- Add 33k safety resistor to bias pot
- Add 33k safety resistor to bias pot
- Remove Master Vol brite cap
- Remove Master Vol brite cap
- Reduce 10pf cap to 5pf across 3.3 Meg resistor in reverb mix circuit
- Reduce 10pf cap to 5pf across 3.3 Meg resistor in reverb mix circuit
- Increase cascode input cap C53 to 0.015uf for slight increase in LF response in FAT mode
- Increase cascode input cap C53 to 0.015uf for slight increase in LF response in FAT mode
- Remove bootstrap network and fully bypass 1st cascode stage
- Remove bootstrap network and fully bypass 1st cascode stage
- Remove brite cap and decrease HF-cut cap to 1nf in attenuator network after CHA tone stack
- Remove brite cap and decrease HF-cut cap to 1nf in attenuator network after CHA tone stack
- Increase bootstrap cap to 2.2nf in 2nd cascode stage for a mid-boost in FAT mode
- Increase bootstrap cap to 2.2nf in 2nd cascode stage for a mid-boost in FAT mode
- Decrease PI input cap to original 1nf and remove grid stopper at PI input
- Decrease PI input cap to original 1nf and remove grid stopper at PI input
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