https://theultimatetone.com/ Mon, 11 May 2026 12:48:01 +0000 MyBB https://theultimatetone.com/Thread-Friedman-Suhr-PPIMV Mon, 17 Feb 2025 09:58:33 +0000 physics]]> https://theultimatetone.com/Thread-Friedman-Suhr-PPIMV


I was wondering if anyone had any thoughts on the "new" master volume that Friedman and Suhr amps seem to be using, as seen on the Plex and SL68 amps. Bias grid-leaks are replaced with 2M2 resistors, and each resistor gets one gang of a dual gang pot (each gang wired as a rheostat) in parallel with it. As you turn down the pot, you reduce the grid-leak value and load down the phase inverter, or such is my current understanding.

I'll post a sketch after some sleep.

Thanks,
          physics

Edit: sketch

  20250217_132837.jpg (Size: 1.26 MB / Downloads: 41) ]]>


I was wondering if anyone had any thoughts on the "new" master volume that Friedman and Suhr amps seem to be using, as seen on the Plex and SL68 amps. Bias grid-leaks are replaced with 2M2 resistors, and each resistor gets one gang of a dual gang pot (each gang wired as a rheostat) in parallel with it. As you turn down the pot, you reduce the grid-leak value and load down the phase inverter, or such is my current understanding.

I'll post a sketch after some sleep.

Thanks,
          physics

Edit: sketch

  20250217_132837.jpg (Size: 1.26 MB / Downloads: 41) ]]> https://theultimatetone.com/Thread-Am-I-miss-something-about-this-FX-Loop-Design Fri, 14 Feb 2025 16:07:39 +0000 makinrose]]> https://theultimatetone.com/Thread-Am-I-miss-something-about-this-FX-Loop-Design
Here's a schematic someone posted for the Badger: suhr_badger_schematic.pdf]]>
Here's a schematic someone posted for the Badger: suhr_badger_schematic.pdf]]> https://theultimatetone.com/Thread-D-PRE-BUILD-mini-marshmallow-preamp Wed, 21 Feb 2024 19:14:04 +0000 coco]]> https://theultimatetone.com/Thread-D-PRE-BUILD-mini-marshmallow-preamp https://theultimatetone.com/Thread-Has-anyone-had-experience-with-the-Garnet-Stinger-circuit Fri, 15 Dec 2023 15:27:32 +0000 makinrose]]> https://theultimatetone.com/Thread-Has-anyone-had-experience-with-the-Garnet-Stinger-circuit
 The design is intriguingly simple---a parallel input gain stage that uses a 6AN8 with the signal going into the pentode section of the tube which is grid-leak biased and direct coupled into the triode section.  The sound is then mixed into the parallel normal input stage's output.   The one thing I'm not clear on is that since the fuzz/distortion it goes through two gain stages wouldn't be out of phase with the normal input stage's signal?

  garnet_l90_b90_rebel.pdf (Size: 438 KB / Downloads: 4) ]]>
 The design is intriguingly simple---a parallel input gain stage that uses a 6AN8 with the signal going into the pentode section of the tube which is grid-leak biased and direct coupled into the triode section.  The sound is then mixed into the parallel normal input stage's output.   The one thing I'm not clear on is that since the fuzz/distortion it goes through two gain stages wouldn't be out of phase with the normal input stage's signal?

  garnet_l90_b90_rebel.pdf (Size: 438 KB / Downloads: 4) ]]> https://theultimatetone.com/Thread-6v6-preamp Mon, 26 Jun 2023 23:17:29 +0000 mooreamps]]> https://theultimatetone.com/Thread-6v6-preamp
My next project.]]>
My next project.]]> https://theultimatetone.com/Thread-Load-Line-Assistance-Needed Thu, 10 Nov 2022 13:57:28 +0000 dtbradio]]> https://theultimatetone.com/Thread-Load-Line-Assistance-Needed
This is my first post on this forum. Fitting for a tube noob, lol! 

For my first question/problem, I need to be pointed to clear and concise info on how to plot a loadline for a tube. In particular, I have 12AX7, 12AU7, 12AZ7, 6K6, and 6V6 tubes around some of which I plan on building a guitar amp. I've been to several websites and done Google searches, but haven't found anything that truly cleared up the mud with regards to plotting load lines. My first BIG question is plate voltage. Do you use the unloaded B+, or measure it under a DC tube load?

Thanks in advance for any helpful replies!]]>
This is my first post on this forum. Fitting for a tube noob, lol! 

For my first question/problem, I need to be pointed to clear and concise info on how to plot a loadline for a tube. In particular, I have 12AX7, 12AU7, 12AZ7, 6K6, and 6V6 tubes around some of which I plan on building a guitar amp. I've been to several websites and done Google searches, but haven't found anything that truly cleared up the mud with regards to plotting load lines. My first BIG question is plate voltage. Do you use the unloaded B+, or measure it under a DC tube load?

Thanks in advance for any helpful replies!]]> https://theultimatetone.com/Thread-Troubleshooting-50Hz-noise-in-phase-inverter Sat, 29 Jan 2022 13:12:51 +0000 Tomislaw]]> https://theultimatetone.com/Thread-Troubleshooting-50Hz-noise-in-phase-inverter
I've just finished troubleshooting a 1972 Marshall 2040 Artiste which intially didn't seem to need much attention apart from a complete recap and bias adjustment. While I was testing it I thought the hum coming from it was a bit too noticeable for my taste so I decided to get rid of it. It's taken quite a bit of detective work to fix something that seemed like a minor problem. I hope this will help others trying to fix the same problem in their amps as you're not getting much information trying to google for PI noise issues.

I knew I would end up rearranging ground connections entirely, but I decided to begin with elevating heaters. That immediately killed all hum coming from both preamps, but there was still some leftover 50Hz hum which sounded like a ground loop. I ripped all ground connections up and rewired everything back in correct order, but surprisingly that didn't do much to eliminate the hum, which wasn't already too distracting, but I wanted to find out what was causing it. 

I narrowed it down to the phase inverter - grounding the input capacitor would kill the hum. At this point I knew it wasn't a ground loop because I disconnected everything before the PI including the B+ to preamps and reverb and that didn't change a thing. I quickly discovered that the first grid wire was picking up a lot of AC noise as untwisted (!) heavy gauge heater wires from the transformer were laid right beside the PI tube which is located on the other side of power tubes. 

Installing a piece of shielded cable on the grid connection helped but only a little bit. I disconnected heater wires, twisted them together and soldered them back, moving them as far from V4 as possible as well. I hoped that would be the end of the battle, but there was still some 50Hz hum in the output! 

I realized that it must be the AC wires on the voltage selector which is very close to the PI circuit. I disconnected all wires, made a fixed connection on the 230V tap and moved everything away from the V4 - and that was it. The hum was now completely gone, but I found it difficult to reconnect the voltage switch. I tried putting the whole bunch of wires inside a braided shield, but that wasn't enough to keep the AC interference away from the PI. I guess installing a shielding plate below the switch would fix the problem nicely, but since it's unlikely that the amp owner will ever use other voltage than 230V, I left the voltage switch unconnected and zip tied all cables away from V4. Now the amp is dead silent. 

There was also a bit of hum inside the reverb circuit and it was entirely caused by RCA jack wires touching heater wires! Another jarring lead dress mistake in an old Marshall. Fortunately this was very easy to fix. 

Tomi]]>
I've just finished troubleshooting a 1972 Marshall 2040 Artiste which intially didn't seem to need much attention apart from a complete recap and bias adjustment. While I was testing it I thought the hum coming from it was a bit too noticeable for my taste so I decided to get rid of it. It's taken quite a bit of detective work to fix something that seemed like a minor problem. I hope this will help others trying to fix the same problem in their amps as you're not getting much information trying to google for PI noise issues.

I knew I would end up rearranging ground connections entirely, but I decided to begin with elevating heaters. That immediately killed all hum coming from both preamps, but there was still some leftover 50Hz hum which sounded like a ground loop. I ripped all ground connections up and rewired everything back in correct order, but surprisingly that didn't do much to eliminate the hum, which wasn't already too distracting, but I wanted to find out what was causing it. 

I narrowed it down to the phase inverter - grounding the input capacitor would kill the hum. At this point I knew it wasn't a ground loop because I disconnected everything before the PI including the B+ to preamps and reverb and that didn't change a thing. I quickly discovered that the first grid wire was picking up a lot of AC noise as untwisted (!) heavy gauge heater wires from the transformer were laid right beside the PI tube which is located on the other side of power tubes. 

Installing a piece of shielded cable on the grid connection helped but only a little bit. I disconnected heater wires, twisted them together and soldered them back, moving them as far from V4 as possible as well. I hoped that would be the end of the battle, but there was still some 50Hz hum in the output! 

I realized that it must be the AC wires on the voltage selector which is very close to the PI circuit. I disconnected all wires, made a fixed connection on the 230V tap and moved everything away from the V4 - and that was it. The hum was now completely gone, but I found it difficult to reconnect the voltage switch. I tried putting the whole bunch of wires inside a braided shield, but that wasn't enough to keep the AC interference away from the PI. I guess installing a shielding plate below the switch would fix the problem nicely, but since it's unlikely that the amp owner will ever use other voltage than 230V, I left the voltage switch unconnected and zip tied all cables away from V4. Now the amp is dead silent. 

There was also a bit of hum inside the reverb circuit and it was entirely caused by RCA jack wires touching heater wires! Another jarring lead dress mistake in an old Marshall. Fortunately this was very easy to fix. 

Tomi]]> https://theultimatetone.com/Thread-Submini-tubes Fri, 24 Dec 2021 15:25:46 +0000 SGillespie]]> https://theultimatetone.com/Thread-Submini-tubes I'm a pedal builder who is looking to get into using tubes (specifically subminiature tubes)for pedals and hopefully preamps eventually. I know a fair amount about pedal design but the use of tubes is not something that I come across very often and know next to nothing about how to begin. Does anyone have experience with designing with submini tubes or know where I can go to learn?
Cheers 
Steve]]> I'm a pedal builder who is looking to get into using tubes (specifically subminiature tubes)for pedals and hopefully preamps eventually. I know a fair amount about pedal design but the use of tubes is not something that I come across very often and know next to nothing about how to begin. Does anyone have experience with designing with submini tubes or know where I can go to learn?
Cheers 
Steve]]> https://theultimatetone.com/Thread-Suggestions-for-BJT-Tremolo-Oscillator Mon, 02 Aug 2021 18:45:00 +0000 makinrose]]> https://theultimatetone.com/Thread-Suggestions-for-BJT-Tremolo-Oscillator https://theultimatetone.com/Thread-Power-Resistors-in-kits Wed, 02 Jun 2021 07:53:55 +0000 Strelok]]> https://theultimatetone.com/Thread-Power-Resistors-in-kits

I noticed that in the kits there are no Power Resistors anymore for local decoupling.


Or so it seems.
Maybe they are rated 1 Watt and I just don't see it.


In earlier times it was advised to raise them above the PCB or circuit card, but I don't see that notice anymore.
Have the resistors become so much cooler?


Also, it was always advised to make a shape with the legs instead of just keeping them straight.
I always wondered what that is about.
I can think of only one scenario:
The Power Resistor gets very, I mean extremely hot in case of some failure.
It melts, no it boils the solder and threatens to do a "melt down": sink down the solder holes onto the board.
There it could make a short if it touches another component on the way down.
Therefore the legs are bent, so that it can not lower itself onto the board.


Kind regards,

Eric-Jan]]>

I noticed that in the kits there are no Power Resistors anymore for local decoupling.


Or so it seems.
Maybe they are rated 1 Watt and I just don't see it.


In earlier times it was advised to raise them above the PCB or circuit card, but I don't see that notice anymore.
Have the resistors become so much cooler?


Also, it was always advised to make a shape with the legs instead of just keeping them straight.
I always wondered what that is about.
I can think of only one scenario:
The Power Resistor gets very, I mean extremely hot in case of some failure.
It melts, no it boils the solder and threatens to do a "melt down": sink down the solder holes onto the board.
There it could make a short if it touches another component on the way down.
Therefore the legs are bent, so that it can not lower itself onto the board.


Kind regards,

Eric-Jan]]> https://theultimatetone.com/Thread-FX-Loop-Bypass-Signal-Loss Sun, 25 Apr 2021 07:56:22 +0000 NGW]]> https://theultimatetone.com/Thread-FX-Loop-Bypass-Signal-Loss
Attached is a schematic showing the FX Loop I used in an amp that I built for a local pro. (The preamp shown is not in his amp, which has switchable Clean and Drive modes.)
He wanted a serial loop, for a Delay pedal, followed by a Reverb pedal (fitted inside the cab), instead of built in reverb and a panel knob to control the reverb level.
I achieved this with the attached circuit.

He recently asked if I could make a foot switchable bypass for the serial loop so he could mount his Delay pedal in the cab also and then just use the amp foot switch box, instead of adding the delay pedal out front. I was able to do this by repurposing one foot switch's function that he didn't use and changing that relay's wiring, as shown and adding a panel switch, as well.
Initially I had it wired so that the loop return was switched in and out, but that meant I lost the Delay Tails.
I rewired it to switch the send in and out, which retained the tails, but the Delay pedal output Z is loading down the bypass signal and there is a volume drop; it works great with no pedal, which is not the object of the exercise.

I would like to find a way to have the Tails and no signal loss in bypass, but I am struggling to find a solution.
If any of you can suggest a suitable way to fix this, I will be very grateful. Otherwise I will change back to loop return switching and he will have no Delay Tails when bypassing the loop.

Cheers, Noel


  40C110 - FX Loop Bypass. 2302021.pdf (Size: 709.88 KB / Downloads: 8) ]]>
Attached is a schematic showing the FX Loop I used in an amp that I built for a local pro. (The preamp shown is not in his amp, which has switchable Clean and Drive modes.)
He wanted a serial loop, for a Delay pedal, followed by a Reverb pedal (fitted inside the cab), instead of built in reverb and a panel knob to control the reverb level.
I achieved this with the attached circuit.

He recently asked if I could make a foot switchable bypass for the serial loop so he could mount his Delay pedal in the cab also and then just use the amp foot switch box, instead of adding the delay pedal out front. I was able to do this by repurposing one foot switch's function that he didn't use and changing that relay's wiring, as shown and adding a panel switch, as well.
Initially I had it wired so that the loop return was switched in and out, but that meant I lost the Delay Tails.
I rewired it to switch the send in and out, which retained the tails, but the Delay pedal output Z is loading down the bypass signal and there is a volume drop; it works great with no pedal, which is not the object of the exercise.

I would like to find a way to have the Tails and no signal loss in bypass, but I am struggling to find a solution.
If any of you can suggest a suitable way to fix this, I will be very grateful. Otherwise I will change back to loop return switching and he will have no Delay Tails when bypassing the loop.

Cheers, Noel


  40C110 - FX Loop Bypass. 2302021.pdf (Size: 709.88 KB / Downloads: 8) ]]> https://theultimatetone.com/Thread-Not-So-Subtle-Sag Thu, 15 Apr 2021 11:24:50 +0000 Strelok]]> https://theultimatetone.com/Thread-Not-So-Subtle-Sag


FireBottle... who came up with that name?



A long time ago I built a Sustainor Preamp.
Like I said so many times: this preamp rocks!


I tried new tubes in it, and they were doing a "new tube" thing.

They gave a sag that was *not* subtle!
The harder I hit the strings, the slower the sound came up.

It was fantastic!
After a while the effect was gone though.

As far as I have seen, the SUS kit works time based, there are a few resistors that set the time.
Can it do this kind of sag?


I have an EHX "Attack Decay", that one works by peaks.
When it detects a peak the preset attack and decay times are applied, so that is only based on preset times.

Fun Fact:
This thing can do something I have not seen anywhere else.
If you apply "poly mode" each note that you play gets its own attack and decay, even if you play multiple notes and let them ring!
I have no idea how they did this.
You would have to sample each note seperately as they are played and then play back a sample with the correct envelope.

But how can you extract the different notes?

Nice riddle to think about, but no solution available!



Strelok]]>


FireBottle... who came up with that name?



A long time ago I built a Sustainor Preamp.
Like I said so many times: this preamp rocks!


I tried new tubes in it, and they were doing a "new tube" thing.

They gave a sag that was *not* subtle!
The harder I hit the strings, the slower the sound came up.

It was fantastic!
After a while the effect was gone though.

As far as I have seen, the SUS kit works time based, there are a few resistors that set the time.
Can it do this kind of sag?


I have an EHX "Attack Decay", that one works by peaks.
When it detects a peak the preset attack and decay times are applied, so that is only based on preset times.

Fun Fact:
This thing can do something I have not seen anywhere else.
If you apply "poly mode" each note that you play gets its own attack and decay, even if you play multiple notes and let them ring!
I have no idea how they did this.
You would have to sample each note seperately as they are played and then play back a sample with the correct envelope.

But how can you extract the different notes?

Nice riddle to think about, but no solution available!



Strelok]]> https://theultimatetone.com/Thread-Which-cable Mon, 12 Apr 2021 17:13:52 +0000 Strelok]]> https://theultimatetone.com/Thread-Which-cable

I'm in the market for buying soms shielded cable.
I used Doug Hoffmans cable, but now I wnat to order at Mouser with the rest of the parts.

I can't find good cable there, what do you folks use?


Warm regards,


Strelok]]>

I'm in the market for buying soms shielded cable.
I used Doug Hoffmans cable, but now I wnat to order at Mouser with the rest of the parts.

I can't find good cable there, what do you folks use?


Warm regards,


Strelok]]> https://theultimatetone.com/Thread-Stereo-Reverb-as-in-TUT2 Sun, 28 Mar 2021 13:32:29 +0000 Strelok]]> https://theultimatetone.com/Thread-Stereo-Reverb-as-in-TUT2

I'd like to build the Stereo Reverb as in TUT2.
Has anyone done that?

Which Reverb Block would be best, the one in the LP Standard or the Standalone Reverb Kit?


Greetings,

Strelok]]>

I'd like to build the Stereo Reverb as in TUT2.
Has anyone done that?

Which Reverb Block would be best, the one in the LP Standard or the Standalone Reverb Kit?


Greetings,

Strelok]]> https://theultimatetone.com/Thread-EL34-glowing-internally-with-signal Wed, 03 Mar 2021 22:58:16 +0000 liquidair]]> https://theultimatetone.com/Thread-EL34-glowing-internally-with-signal
(Sorry if this is in the wrong place, I didn't see a "Power Amp" section of the forum!)]]>
(Sorry if this is in the wrong place, I didn't see a "Power Amp" section of the forum!)]]>