Article written in 2015. NOTE: This website is frequently updated. Last update September 2023

David Gilmour's Tube Drivers

David Gilmour has been an avid Tube Driver user since around 1993. His first known use was the recording sessions for Pink Floy's The Division Bell album in 1993. Those same sessions also resulted in the Division Bell companion album, Pink Floyd's The Endless River, which was not completed until 2015. He used Tube Drivers extensively for his 2006 album On an Island and the subsequent tour, heard on the Remember That Night and Live in Gdansk concert releases, as well as his 2015 Rattle that Lock album and tour, and his 2017 live album, Live at Pompeii. His collection of Tube Drivers includes several 1980s originals, several 911 Tube Drivers, a few gold Tube Works 911 Tube Drivers, and the five knob Real Tube version from Tube Works.

"David started using a Tube Driver during recording for the Division Bell album in 1993 and has used them ever since. It is his main go to distortion. We have tried all the variants - Chandler ones with in line PSU, 3 Knob version, rack mount, etc but the only one he likes are the original mains powered 4 knob with "designed by BK Butler" on the top. He does not use any with the bias control fitted." - Phil Taylor, Guitar tech for David Gilmour - June 2018 issue of Tonequest

"The overdrive I tend to use is a (BK Butler) Tube Driver these days, often with a compressor feeding into it. On this one (Rattle That Lock), it’s actually pretty much untreated." - David Gilmour from Guitarist Magazine 2015

The Tube Driver circuit has its own unique compression and overdrive tone that does not sound quite like any other overdrive. David often uses it with a compressor and he has used various compressors over the years. A few of his favorites being the Boss CS-2 and Demeter Compulator. Compressors compress the signal level, making light picking and hard picking intensity sound closer to the same volume, boosting the low levels and reducing the high levels. They make the playing sound smoother and increases the sustain. David's super smooth and creamy overdriven tones are due to that combination of compressor and the TD's own natural compression, along with the way he plays. Add is some delay to smooth out the signal even more and it is tonal heaven.

To recreate David's Tube Driver tones, I think it is best to use clean, Gilmourish amps such as the Hiwatt Custom 50 (DR504), Custom 100 (DR103), Fender Bassman, or Fender Bandmaster. Those were the magical combinations heard in Gilmour's work from 1990 and onward. For those Pulse or On an Island era light drive and heavy overdrive tones through a Hiwatt or Fender amp, this is your pedal. You can hear it in songs like Coming Back to Life, Marooned, A Great Day for Freedom, and the live versions of Shine on You Crazy Diamond from Pulse, Remember that Night, and Live in Gdansk. It was the primary overdrive and distortion pedal for David's On an Island tour. He even used it to mimic the sound of the Selmer Bass & Treble amps that Syd Barrett used in the early Pink Floyd.

David previously used other overdrives, such as the Colorsound Power Boost, Pete Cornish ST-2 Booster, and a Mesa Boogie Mark 1 head (used as an overdrive in his signal chain) in the 1980s. Once he switched to the TD it remained his primary overdrive pedal. You can read more about the Butler Tube Driver HERE. A list of the different versions of the Tube Driver can be found HERE.

Here are a few examples I recorded of the Gilmour Tube Driver sound.

mp3 Shine On You Crazy Diamond noodling - Boss-CS-2 > 911 Tube Driver > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG-SA pickups into a Reeves Custom 50.

mp3 Time Solo - Strat into a 911 Tube Driver > Future Factory delay > Reeves Custom 50

mp3 Echoes solo #2 (Live at Pompeii style) - Strat into a 911 Tube Driver > Future Factory delay > Hiwatt DR103

mp3 Fat Old Sun - Telecaster into a 911 Tube Driver > Future Factory delay > Reeves Custom 50

mp3 Take A Breath solo - Demeter Compulator > Tube Works 911 Tube Driver > Future Factory Delay > Ambi Space Plate Reverb > Reeves Custom 50. Strat with SD SSL5 pickup.

mp3 Castellorizon - BKB 911 Tube Driver > TC Nova delay into a Reeves Custom 50. Stratocaster with EMG pickups.

mp3 In Any Tongue solo - Tube Works 911 Tube Driver > Future Factory Delay > Ambi Space Plate Reverb > Reeves Custom 50

mp3 Pigs Outro solo - Tube Works 911 Tube Driver > Future Factory Delay > Ambi Space Plate Reverb > Reeves Custom 50

mp3 Calling Part 2 (guitars) - 1980s BKB/Chandler Tube Driver > Boss CE-2 Chorus > TC Nova delay into Fender Bassman. Stratocaster with EMG pickups and E-bow.

mp3 5 A.M. - Boss CS-2 compressor > 1980s BKB/Chandler Tube Driver > TC Nova delay into a Reeves Custom 50. Les Paul with P-90 pickups and Bigsby tremolo.

mp3 Louder Than Words - Demeter Compulator > BKB/Chandler Tube Driver > Deluxe Electric Mistress (70% mixed in with a blend pedal) > TC Nova Delay > Reeves Custom 50

mp3 Coming Back to Life solos - Boss CS-2 compressor >1980s BKB/Chandler Tube Driver > Boss CE-2 chorus > TC Nova delay. First solo with EMG-SA neck+middle pickup. Second with neck pickup.

DIVISION BELL and THE ENDLESS RIVER - For Pink Floyd's 1993 recording sessions for the Division Bell and The Endless River albums, David used several versions of the Tube Driver. The pedal on the left is the Dean Markley Overlord (a knockoff of the Real Tube). It is barely visible, but there is a power switch on the back and Dean Markley script above it. To the right of that is a 1980s Tube Works 901 Real Tube. On the far right are two1986-87 period BKB/Chandler Tube Drivers. It is unknown which of these were actually used for the album tracks, but since David used two 1986-87 Tube Drivers in his Division Bell tour rig 1994, it was likely those.

Tube Drivers from Pink Floyd's 1993 Division Bell sessions - (left to right) Dean Markley Overlord, Tube Works Real Tube, two B.K. Butler/Chandler Tube Drivers


(left to right) A Tube Works 901 Real Tube pedal from 1987, a Dean Markley Overlord from 1988 (Real Tube knockoff), and a 1986-87 B.K. Butler/Chandler Tube Driver


PULSE TUBE DRIVERS - David used two original 1986-87 BK Butler/Chandler branded Tube Drivers in his 1994 Division Bell live rig. These have become known as the "Pulse" Tube Drivers, as that is the name of Pink Floyd's popular live concert video and album from the 1994 tour. The red knobbed one was labeled #1 and the other #2. Both had identical settings on the first leg of the tour. Later in the tour, and likely the final 14 concerts at Earls Court in 1994 (heard on the Pulse album and video), David set the DRIVE and LO higher on his #2 Tube Driver.

A common mistake people make is to set their modern 911 Tube Driver to David's exact Pulse settings and expect it to sound the same, but 911 Tube Drivers do not have the same pots or circuit as the older Tube Drivers. In fact, I have found that each version of the Tube Driver requires different settings to sound the same. Even the 1986-87 Tube Drivers with the same circuit could sound different from one to the next.

David Gilmour's 1994 Pink Floyd pedal board with two 1986-87 BKB/Chandler Tube Drivers labeled #1 and #2. These settings were used prior to the Earls Court concerts, released as the Pulse live album and video, so may not represent what was heard in those recordings.

I suspect the circuits in both of David's TDs were the more common second version from 1987, but there is no way to know for sure. You can read more about these Tube Drivers HERE. A list of the different versions of the Tube Driver can be found HERE.

Gilmour's #1 and #2 BKB/Chandler Tube Driver settings from the 1994 Pink Floyd tour (left) and what those same settings would be on a BK Butler 2006 911 Tube Driver (right). Your results may vary though, as all BKB/Chandler TD's do not sound the same.

Gilmour revised his #2 Tube Driver settings for the October Earls Court concerts, shown above. These are likely the overdrive settings heard on the Pulse album and concert video. The #2 Tube Driver was used for almost all of the overdrive rhythm guitar and overdrive solos heard in songs like Shine On..., Astronomy Domine, Learning to Fly, On the Turning Away, Another brick in The Wall II, Time, and Coming Back to Life.

These are David's revised #2 Tube Driver settings (left), and what they would be on a 2006 model 911 Tube Driver (right). This overdrive tone is most likely what was heard on the Pulse concert album and video recording from the final Earls Court concerts. Again, Your results may vary, as all BKB/Chandler TD's do not sound the same.

The Sovtek Big Muff was David's primary distortion pedal for Pink Floyd's 1994 Division Bell tour. According to the the signal router visible in David's effects rack during the concerts (LEDs indicated which effects were on for any given song), the #1 Tube Driver was placed before the Muff and the #2 was placed after it. Each of those placements affects the the Big Muff sound slightly differently.

David almost always ran the #1 Tube Driver before the Big Muff or Rat for his high gain solos, but for the Time solo played in the European leg of the tour, he sometimes ran the Big Muff into the #2 Tube Driver which followed it. The #2 Tube Driver was also used for most of the overdrive tones, sometimes combined with a Boss CS-2 or Cornish SS-2. For David's 2006 On an Island tour, the Tube Drivers always came after the P-1 and G-2 in the signal chain. David did not blend Tube Drivers with the muffs at all for his 2015/16 Rattle That Lock tour.

"David doesn't necessarily use anything exactly as it is, or as you would expect. There are times when he has run a Big Muff into various things such as a Boogie head or a BK Butler Tube Driver..." - Phil Taylor, 2009 Guitar Player


ON AN ISLAND TOUR, REMEMBER THAT NIGHT, and LIVE IN GDANSK - Gilmour's 2006 On an Island Tour effects board used two new model 911 B.K. Butler Tube Drivers, made in 2005. Both were placed after the Big Muffs in the signal chain. These were a reissue of the Tube Works model 911 Tube Driver from the 1990s, not the 1980s Tube Drivers. The 911 had a slightly different circuit than the 1980s BK Butler/Chandler Tube Drivers David used in '94, as well as different pots. One TD was set for high gain overdrive, and the other was set for a light drive to blend with the Big Muffs (P-1 and G-2), and for use alone. These were David's primary overdrive and distortion pedals for the tour, and I would estimate 75% of the guitar solos heard on that tour were played with one of these Tube Drivers. You can read more about the Tube Drivers in this rig HERE

I don’t use the Big Muff or the Fuzz Face as much anymore. I currently have two BK Butler Tube Drivers on my pedalboard, and I just use one or the other. If I need a little something more, I’ll stomp a compressor with a bit of drive onto the beginning of it, and that will turn things up another whole gear - David Gilmour

"He has always had two (Tube Drivers) in his guitar setup, since '94, one set on minimum gain, the other more. During most of the On An Island Tour in 2006 he used the second one instead of using a Big Muff in Comfortably Numb, giving a different character of sound. On the last tour 2015-16 he had three in his setup, each set to a different amount of distortion" - Phil Taylor, Guitar tech for David Gilmour - June 2018 issue of Tonequest

Cornish Mk II Board Settings

(shown above) David Gilmour's MK2 Pete Cornish effects board settings from his 2006 tour, including two B.K. Butler Tube Drivers made in 2005


RATTLE THAT LOCK TOUR - David brought out the Tube Drivers again for his 2015/16 tour, shown below. This time he used an original 1980s BK Butler/Chandler branded Tube Driver and two more recent B.K. Butler 911 Tube Drivers. Each was set for a slightly different tone and level of drive. David did not use them to boost/blend with his Big Muffs on this tour. They were only used as overdrives, blended with one of his three compressors. It is unkown which circuit was inside the 1980s Tube Driver, as Butler stated shipped David four 911 TD circuits in 2005, requested to replace the circuits in his old Tube Drivers.

(left to right) A 1986-87 BKB/Chandler Tube Driver (#1) and two BK Butler 911 reissue Tube Drivers (# 2 and #3) on David Gilmour's 2015/2016 pedal board. All had been modified with custom power supplies

These are David's Tube Driver #2 settings from his Rattle That Lock tour (left), and what they would be on a 2006 model 911 Tube Driver (right). This is assuming that the circuit inside that 1986-87 Tube Driver is the more common variant with the green backed pcb.

The #1 Tube Driver with the red drive knob was actually used for most of the lower gain tones, despite the fact that the red drive knob shows a high gain setting. There is a sticker visible on top of that TD that appears to say GAIN SWITCH, and what appears to be a switch on the back of the TD. The fact that this TD does not have a high gain sound indicates that it has had some type of modification to reduce the gain, which probably explains why it was given a red knob cap.

David's 2016 Rattle That Lock tour Tube Drivers shown from the top and rear. Note the "gain switch" sticker on the TD on the left and what appears to be a switch on the back of the pedal, indicating that it has had some type of gain modification

A 1980s BKB Tube Driver (left) and a Tube Works gold plated 911 Tube Driver from David's gear warehouse

A 1980s BKB Tube Driver (left) and two Tube Works gold plated 911 Tube Drivers used for the Peter Green Celebration concert in 2020

............Mistress Mystery Page. .... . .

BOOSTING A BIG MUFF WITH A TUBE DRIVER - What the boost does really depends on the settings of the booster and the Muff and where the booster is placed in the chain, before or after the Muff. Placing an overdrive after the Muff seems to be a bit smoother, and before the Muff usually has more crunch and attack, but it can be the exact opposite depending on the settings. Which one is "driving" - meaning which has the higher gain - has an effect on the distortion tone. You can get harsh top end, smooth top end, boomy lows, light lows, or whatever you want if the booster has a tone control, or better, a bass and treble control.

The Muff sustain can be set high and the drive on the booster pedal low, or vise versa. Each yields a slightly different tone. Set the booster pedal's bass and treble or tone knob to be as transparent as possible, in that the clean tone is not colored when the booster is switched on. I suggest starting with the booster placed after the Big Muff. Set the Big Muff sustain and booster drive both at 50%. Then adjust the Muff sustain up, booster drive down until you get the tone you want. Then try it the other way around, with the drive pedal having the high gain and the Muff low gain, and decide if you prefer one way or the other. - or prefer no boost.

If the sound craps out and sounds farty, or drops out when playing the low E string, there is too much gain from one pedal or the other causing the signal to overload and break up. Experiment with the gain/drive of each pedal until you have a sound that is almost to the point of breaking up. If you can't find a suitable sound with the booster placed after the Big Muff, try the procedure again with the boost in front of the Muff. Keep in mind, some vintage and boutique Big Muffs sound so good at high gain that you may not see any advantage to blending it with aboost pedal.

HOW DAVID BOOSTED BIG MUFFS WITH A TUBE DRIVER - When David used his Tube Driver + Muff combination for the high gain solos on Pink Floyd's 1994 Division Bell tour (heard on Pulse), the TD nearly always came first in the signal chain before the muff. The only time it came after the Big Muff (or P-2) was for the Time solo. For David's 2006 On an Island tour, the Tube Drivers always came after the P-1 and G-2 in the signal chain. He did not blend Tube Drivers with the muffs at all for his 2015/16 Rattle That Lock tour.

Below are Tube Driver + Big Muff sound clips demonstrating the difference between a Tube Driver placed before a Big Muff and Tube Driver after a Big Muff in the signal chain. The TD and Muff settings were identical in each clip. The TD after the muff sounds more overdriven and on the edge of breakup than the one before, but the settings on each pedal can be changed to sound like the opposite.

mp3 Tube Driver before Sovtek Big Muff

mp3 Tube Driver after Sovtek Big Muff

Based on David's 1994 Division Bell tour signal chain and effect settings, his On an Island tour settings, and listening to the official recordings and bootlegs, he used the Tube Driver to blend with the Big Muff. The purpose was NOT for a volume boost - it was simply to blend the two pedals into one for a more pleasing and effective Big Muff lead tone. This combo tames the Big Muff distortion ever so slightly to reduce the buzziness and refine the crunch of the attack, along with a little EQ tone altering. It is a very subtle effect, and the mistake I see most people making is setting the gain of the booster pedal too high and making the Big Muff sound like a noisy, farty, muffled mess. When David did this in 1994, it only affected the tone of his Big Muffs in a minor way.

Here are instructions to set up the Big Muff/Tube Driver combo heard on David's 2006 solo tour, as captured on the Remember That Night DVD and Live in Gdansk. Note that these settings are for a Strat with a hot single coil bridge pickup, through a loud, clean tube amplifier. David's settings make make the Big Muff right on the edge of choking. He used a Pete Cornish P-1, which is a very good Ram's Head era Big Muff clone, into a 2005 BK Butler 911 Tube Driver. If you have a 1990s Real Tube 911 Tube Driver or a BKB 911 Tube Driver made since 2006 you will notice when you turn the knobs you can feel the pot notches click by.

1. Set both Big Muff and Tube Driver knobs to David's OAI settings (they are posted here), with the TD following the Big Muff (Cornish P-1). Set the TD drive pot exactly three notches from zero (the ones you feel when turning the knob, not the notches printed on the pedal).
2. Turn the Big Muff on, guitar volume at 10, and listen. That is your unity volume.
3. Keep the Big Muff on and switch your TD on. If the unity volume goes down, adjust your TD volume until there is no difference in volume with the TD on or off. Some people may like the volume to boost a bit when they hit the TD, but for now keep them the same.
4. The Big Muff should be right on the edge of breakup. Turn the TD drive pot down one notch and listen for your unity to drop. If it does not drop, turn the drive down another notch. Whatever notch position brings the unity down, you want to be one notch above that. That should give you the exact gain saturation that David had for the OAI tour. One notch too low and the unity drops, one notch too to high and there will be a slight volume boost and too much breakup, but there SHOULD be some signal breakup. It is literally that fine of a line with the 2006 BKB TD. You just want to determine what level of breakup you can handle. You don't want the low strings crapping out and choking on you, but they should choke a bit. This setup works for The Wall Big Muff tones too.

If it breaks up too much for you, back the Big Muff sustain down slightly, and bring the tone up the same amount (the muff tone and sustain circuits are interactive). Find the balance you like in this manner, but if you can't handle that Big Muff breakup through your guitar and amp, then don't boost. This is not a tone that is handed to you, you have to work it out with your fingers, but this is the setup. Note that the instructions above do not work for the 1980s era BKB/Chandler Tube Drivers since those circuit were slightly different, so the drive pot positions may be different.

Here is my favorite setup:

Tube Driver - Placed before the Muff in signal chain. Hi EQ at 4, lo EQ at 6, drive at approximately 1 to 1.5
Muff sustain at about 65-70%, tone about 35%, or whatever tone setting works on your rig in the Gilmour range.

SELMER AMP TONE WITH A TUBE DRIVER - When David joined Pink Floyd in 1968 and took over vocals and guitar for Syd Barrett he was using the same gear that Syd had been using - a Telecaster, Binson Echoec, and Selmer amplifiers and speaker cabinets. The Selmer had a unique, jangly, overdriven sound that a lot of people confuse with a fuzz pedal. There is no fuzz on Piper at the Gates of Dawn, Syd's first Pink Floyd album. He did own a fuzz pedal - a Colorsound Tonebender (not a Vox) - but he rarely used fuzz. His fuzz use was so rare that there is only one photo of him with one, from May 1967, and the Tonbender input is not even plugged in! If you want to hear what Syd's actual fuzz pedal sounded like, listen to the fuzz solo in the See Emily Play single. Otherwise, it's mostly the Selmer.

Syd Barrett and David Gilmour playing through Selmer amplifiers in 1967 and 1968

The Selmer Truvoice Treble 'N' Bass Mark II amplifier (left), which had a normal and a bass channel, and Selmer Stereomaster (right)

The core guitar tone on the Piper album was primarily the 50w Selmer Truvoice Treble 'N' Bass Mark II amp. It was a two channel (normal and bass) 50w amp, and the louder you turned it up, the more it distorted. Syd used the normal channel input. When performing live Syd used the Truevioce or a Selmer Stereomaster amplifier with a matching Selmer speaker cabinets. Those cabs were often sold with the Selmer T&B, and were fitted with Goodman Audiom 61 speakers. I think Vox was also using Goodman speakers at this time.

The Steremaster Syd used essentially sounded the same as his Truevoice T'N'B, but it had two 50w amplifiers built in (50w each for stereo, or 100w mono), each with a series of five pre-set EQ buttons that could be used in addition to the treble and bass knobs. David continued to use those Selmers when he joined the Floyd, as he was basically picking up where Syd left off and using his gear. You can David using them all over A Saucerful of Secrets, More, and Ummagumma.

Below is an extraction of Syd playing guitar through his Selmer and Roger Waters playing bass from the Piper at the Gates of Dawn sessions. The first 17 second of IO is just the Selmer.

mp3 Interstellar Overdrive - Isolated Guitar and Bass

mp3 Astronomy Domine - Guitar Mixed up front

1980s BKB Tube Driver (left) and Tube Works Real Tube settings to mimic the Selmer sound

David soon moved on to Hiwatts and began to develop his own sound. As new material without Syd was written, Pink Floyd stopped playing a lot of those early Selmer era Floyd songs. Later in his career David began playing some of those songs again with the Floyd and in his solo concerts. Astronomy Domine was a staple for his concerts beginning in 1994, but he also played Arnold Layne in later shows, and a one-off performance of Remember A Day. To get those Selmer tones David used a Tube Driver into his Hiwatt amps, which got close, but you can actually get even closer to the Selmer than David did by using 1980s era BK Butler/Chandler Tube Drivers. The 5-knob Real Tube version of the TD from Tube Works also works for this sound. You need a bright, jangly amp tone. A Bassman or Hiwatt are perfect for that. I dial the presence control all the way up on my Hiwatt and set my bright channel volume fairly high. I set the TD for a bright overdrive, dial the volume down sightly on my Telecaster, and play right over the bridge pickup to get the sound as bright as possible. My pedal settings are shown above. Note that not all 1980s Tube Drivers sound the same, so I show a range of LO and DRIVE settings that work on the TDs in my collection.

Here are a couple of sloppy clips of the Selmer tone with a TD.

mp3 Interstellar Overdrive - Telecaster into a 1980s BKB/Chandler Tube Driver > Future Factory delay > Reeves Custom 50.

mp3 Astronomy Domine - Telecaster into a 1980s BKB/Chandler Tube Driver > Future Factory delay > Reeves Custom 50.

There is a hint of fuzz on top of the Selmer tone that is not quite the same with the TD, but in all other respects it sounds very close. You can also get a similar sound with a 1990s era 911 Tube Driver or the 911 TDs Butler has been making since 2006 by dialing the hi and lo knobs to zero. The tone is similar, but not quite as bright and accurate as the 1980s Tube Drivers or Real Tube pedals.

Shown above (left to right) - An original long plate Ei Yugoslavian 12AX7 tube re-branded "TUBE DRIVER" that shipped with the original BKB/Chandler Tube Driver in 1986-87, and a short plate, unbranded Goldern Dragon 12AX7 that ships with the reissue Tube Drivers made since 2006.

WHAT TUBES DID DAVID GILMOUR USE? - There is no reliable information available about the tubes in David's BK Butler/Chandler Tube Drivers used in his 1994 rig or the Tube Drivers in his recording studio, or in his 2015/2016 rig. Butler said he shipped four new 911 Tube Drivers to David in November 2005 with pre-war NOS EI 12AX7/ECC83 tubes made in Yugoslavia (old stock from his Tube Works company), and those could be seen in the Pete Cornish photos of David's Mark II pedal board being built in 2005. He also shipped four more 911 Tube Driver circuits (with Yugo tubes) to replace the circuits in David's older Tube Drivers. However, in the 2020s Butler was advertising that for an extra charge "you can get a very rare, USA made vintage 12AU7 tube installed that Gilmour uses in his Tube Drivers". Pete Cornish has said he did not change the tubes when he built David's 2006 board, but in 2008 he told some people that David used 12AT7s in his Tube Drivers, not 12AX7s.

So what does David actually use in his various Tube Drivers? The bottom line is, no one really knows except Phil Taylor, David's backline tech who takes care of such things, or David himself.

It is worth noting that the type of tube makes no difference in the amount of distortion the Tube Driver generates since the clipping is generated by the op-amp, not the tube. What the tube does is slightly color the tone before the output to the amp. In that way, some tubes may make the distortion at very low drive settings sound smoother than other tubes, but the difference is minimal and probably imperceptible in a band mix. At high drive settings the tube makes little difference. Some people claim they can hear a significant difference between tube types, but I suspect that is due to confirmation bias (which I have been guilty of) and a bit of fairy dust.

I have actually tested this by recording a sound clip into a Boss looper and recording comparison clips at moderate overdrive, with the only difference being a tube change in the TD. I then inverted one of the recordings and did a null test against the other recordings to hear if there were any sound frequncies that did not cancel out. The sound was practically null on all.

IMPEDANCE ISSUES - PUT A BUFFER AFTER IT! - There is a signal impedance issue with Tube Drivers and Real Tube pedals that could cause tone problems in your signal chain. The Tube Driver has a buffered, high impedance input, but no output buffer. The passive tone circuit hangs a high impedance signal on the output, so changes in loading and capacitance can result in a loss of bandwidth, usually high frequencies, altering the tone in a negative way. Your guitar's output impedance is higher at high frequencies and lower at low frequencies, and varies as you play. Since the highs have a higher impedance, you will lose high frequencies if the input impedance of the circuit following the guitar is too low. That same priciple typically applies for each circuit in your signal chain after the guitar as well. That is why you always want a low impedance output from one pedal going into a high impedance input on the next pedal. A good rule of thumb for a well balanced pedal board signal chain is to have the input impedance of each pedal be about 10x larger than the output impedance of the pedal before it.

With moderate drive and treble settings, like Gilmour's low gain TD settings, the TD's output impedance should be around 10KΩ. That's a bit high, but OK if you are just boosting it into a Big Muf, which has an input of 120-130KΩ, or a Boss CE-2 chorus, which has an input of 407KΩ. The output impedance of the TD changes depending on the knob settings though. With high drive, treble, and volume settings, like Gilmour's high gain TD settings, the output can be as high as 90kΩ. In that case a 1MΩ input on the pedal following the TD is a good idea. You can accomplish this by placing a pedal with an always-on 1MΩ buffer, like most modern Boss pedals, immediately after the TD. Or you can place a 1MΩ buffer after the TD, like a Cornish LD-1. Empress, JHS, Fender, and Mesa/Boogie all offered buffer pedals at the time I wrote this article. You can also place the TD in a loop that has a buffer on the output of at least 1MΩ.

The Tube Drivers in David's pedal boards always have a buffer after them, or built into the output, to prevent those tone loss issues. 

WERE DAVID GILMOUR'S TUBE DRIVERS MODDED BY PETE CORNISH? - If you count adding signal buffers and changing the power supplies, then yes. Pete added his tube buffers to the Tube Drivers used in David's 1994 concert rig and his buffer/line driver at the output of the two TDs in David's Mark 2 pedal board used for the On an Island tour in 2006.

The TD already includes an input buffer, but no output buffer. It has a high impedance output, so it is prone to volume and tone changes if it does not see a buffer before going into additional effects. Pete's line driver made the TDs unity gain balanced with the rest of the pedal board. The power transformers inside each TD was also removed and a new 3 stage power supply installed which separately powered the op-amp, tube, and tube heater. A separate supply powered the line drivers.

BK Butler said the units he sold to David were stock and Pete Cornish has stated the actual TD tone circuits inside were not modified by him, but there is an extra resistor added to the 3rd lug of the drive pot in one TD in the Cornish 2006 pedal board that was not added by Butler. There is also one resistor (R2) that appeared to be disconnected in the photos of David's 2006 pedal board being constructed, shown below. The resistor is actually there, just mounted vertically. This 1m ohm pull down resistor is a DC reference resistor that sets the input impedance and is needed to prevent unstable DC level after C1. Test playing the TD straight into your amp with no other pedals, then compare that to sound of the TD in your pedal board chain. If you hear a big differance, you may want to add a larger resistor here (per Mr Butler's advice). Butler suggests a larger 2.2M or 3.3M resistor because the higher the resistor value, the less potential effect it should have on your sound. I found it more effective to run my TDs in a bypass loop with with a buffered pedal immediately after in the signal chain, as in the Cornish boards.

Shown Above (left to right) - BKB Tube Drivers from David Gilmour's 2006 pedal board, and the stock BKB Tube Driver circuit from 2007.

ALTERNATIVES TO THE TUBE DRIVER SOUND - The best alternative to the popular 4 knob Tube Driver is actually the discontinued 5 knob Real Tube pedal, model 901, made by Tube Works and designed by BK Butler. The circuit is a bit more complex, but bascially the same design as the 911 Tube Driver only with a mid range knob added. The 901 model can usually be found used for much less than the old BKB/Chandler or 911 Tube Drivers. With a similar tube, they can sound exactly the same as the 911 version. They are also in a smaller enclosure and have a wider range of sound due to the added mids knob, and so can be tweaked to sound good with a wider range of amps. They can be made to sound like anythng from a Tube Screamer to the Mesa Boogie mark series overdrive sound. When I set my Real Tube to sound the same as my 1980s or 2007 Tube Driver, I can barely hear any difference in a blind sound comparison through my Gilmourish amps (Hiwatt DR103/503, Reeves Custom 50, Fender 59 Bassman). The sound difference is more apparent with some other amps however.

Tube Works Real Tube and US made Ibanez Tube King. Both are modified Tube Driver circuits

What if you just can't get along with any of the Tube Driver/Real Tube circuits because of the signal impedance issues in your pedal board, or have issues with the internal transformer making hum noise? Another alternative is the discontinued BK Butler 1990s era Ibanez Tube King (TK999US), which is a variation on his Real Tube/Tube Driver circuits, only with NO internal transformer. It runs on a standard 9v power supply. At low drive settings the tone is slightly different than a Tube Driver due to the active tone circuit, but it is still closer than most other overdrive pedals. Unlike the Tube Driver and Real Tube, it has a buffered output and because the internal transformer was eliminated, it has no loading issues or transformer noise issues. It is somewhat rare, but could still be found used at the time I wrote this article (2015).

The classic Boss Blues Driver BD-2

There are several alternative, non-tube pedals that can do very similar overdrive tones through Gilmourish amps. Nothing out there that I have tried exactly matches the sound characteristics of Tube Driver circuit with a real tube at both low and high gain, but there are some that do one or the other very well. The stock Boss BD-2 Blues Driver is one of the closest. At high gain, the tone is amazingly similar to the sound of the wide open 911 Tube Driver when combined with a compressor like a Boss CS-2, but it does have a more of a harsher, trebly sound if the tone knob is set too high, and is slightly lacking in the mid range. The BD-2 also matches the low to medium gain Tube Driver tones very well when combined with a comp. I think it sounds fantastic through a Hiwatt or Bassman, but some people find it has a slightly harsh top end through certain amps. The tone range is also limited due to the single tone knob, making it harder to dial in a matching Tube Driver tones on some amps.

Skreddy Lunar Module Deluxe and Buffalo TD-X. TD-X settings shown are for high gain 911 Tube Driver sound

Past FX TD-Y settings to mimic the medium to low gain overdrive of a 911 TD. These same settings work on the Buffalo FX TD-Y

The Buffalo FX TD-X (discontinued) and Skreddy Lunar Module are two other very good alternatives, with much more tonal flexibility than the Blues Driver. The Past FX TD-Y, an improved clone of the TD-X, is another great option. These do an excellent job matching the low to medium gain overdrive of the 911 TD, and are very smooth sounding. When the compressor, chorus, and delay are added, any of these works well for that sound through my Hiwatts or Bassman amps.

Electro Harmonix Hot Tubes and Hot Wax pedals. On the right are my settings to replicate the high gain 911 Tube Driver sound

There are several pedals from Electro-Harmonix that work well as a Tube Driver substitute through Gilmourish amps. Hot Tubes overdrive is one, and it is also a good substitute for David's 1970s Power Boost tones. The EHX Crayon overdrive is another that does the low to medium gain Tube Driver sound well. The EHX Hot Wax is an even better alternative that is very versatile in creating all of David's various Tube Driver tones, including the high gain 911 Tube Driver tones. It is a combination overdrive that includes the Hot Tubes circuit and the EHX Crayon overdrive circuit. With both circuits engaged you can recreate a tone similar to David's 911 Tube Driver tones heard on Remember That Night and Live in Gdansk from his 2006 tour. It also has much more tonal flexibility than the Blues Driver. Here are some comparison sound clips of the high gain Tube Driver sound.

The Buffalo FX 18v Power Boost (discontinued), does the low to medium gain Tube Driver sound, although it may not sound as smooth through certain amps as other pedals on this list. It is a clone of the Colorsound Power Boost with a volume pot added. The Past FX Power Booster is a clone of the Buffalo Power boost, but in a smaller enclosure.

The MXR Fet Driver is a part-for-part replica of a 1980s Tube Driver that uses uses a charge pump to get the +/-15 volts needed. The tube stage was replaced with FETs (field effect transistors). The MXR does the high gain TD overdrive OK, but I could not get the low gain overdrive tones to exactly match a Tube Driver. It was very similar though. The tube in the TD colors the distortion from the op-amp. That may be an effect the FETs in the Fet Driver cannot sucessfully replicate. The MXR has slightly less mid range than the TD, so that could be the difference I hear.

The Hermidia Audio Dover Drive was supposed to be similar to the Tube Driver sound, and it is a good overdrive, but I don't think it sounds any closer to the TD than the MXR Fet Driver. The circuit is like a mix of a Fuzz Face and Zen Drive, so it is very different from the Fet Driver, but it is an OK the low gain 911 TD sounds, but not any more accurate than the Fet Driver.

Effects settings for medium gain overdrive similar to a Tube Driver

Below are some comparison clips of medium gain overdrive. I tried my best to match each pedal to the same sound from a Tube Driver. The same clip was recorded on a looper and played back through each pedal. With the comp, chorus, and delay, it is very difficult to hear any difference between these pedals at low drive settings.

mp3 Shine On You Crazy Diamond noodling - BKB 911 Tube Driver. Boss-CS-2 > TD > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG_SA pickups into a Reeves Custom 50.

mp3 Shine On You Crazy Diamond noodling - Boss BD-2 Blues Driver. Boss-CS-2 > BD-2 > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG_SA pickups into a Reeves Custom 50.

mp3 Shine On You Crazy Diamond noodling - Buffalo TD-X. Boss-CS-2 > TD-X > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG_SA pickups into a Reeves Custom 50.

mp3 Shine On You Crazy Diamond noodling - Buffalo 18v Power Boost. Boss-CS-2 > PB > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG_SA pickups into a Reeves Custom 50.

mp3 Shine On You Crazy Diamond noodling - Skreddy Lunar Module. Boss-CS-2 > LM > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG_SA pickups into a Reeves Custom 50.

mp3 Shine On You Crazy Diamond noodling - MXR Fet Driver. Boss CS-2 > Fet Driver > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG-SA pickups into a Reeves Custom 50.

mp3 Shine On You Crazy Diamond noodling - EHX Hot Wax. Boss CS-2 > Hot Wax > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG-SA pickups into a Reeves Custom 50.

mp3 Shine On You Crazy Diamond noodling - EHX Crayon. Boss CS-2 > Crayon > Boss CE-2B (50%mix) > Future Factory Delay. Strat with EMG-SA pickups into a Reeves Custom 50.

Below is a sound clip replicating the Pulse/1994 tour version of Shine on You Crazy Diamond, demonstrating light overdrive with a stock Boss BD-2 Blues Driver. I use a Boss CS-2 compressor and a Boss CE-2 chorus to get the sound as close to David's 1994 Tube Driver tone as I can. The main difference between the DB-2 sound and the Tube Driver is that the BD-2 is heavier on the high frequencies, and slightly lacking in the mid range. It still sounds fairly close through the right amp.

mp3 Shine On You Crazy Diamond second solo and verse section - Boss BD-2 Blues Driver. Boss CS-2 > Boss BD-2 > Boss CE2 chorus > stereo Future Factory delay (500ms) > stereo Ambi Space plate reverb > Reeves Custom 50 and 59 Bassman

Below are omparison clips of high gain overdrive. The TD-X/TD-Y and Lunar Module do not do the high gain 911 TD sound very well, and definitely not any better than the Boss Blues Driver or EHX Hot Wax. I did find that with EMG pickups the TD-X/TD-Y gets closer to the high gain TD sound than when using single coil, passive pickups.

mp3 Castellorizon - BKB 911 Tube Driver. Strat with Seymour Duncan SSL-5 bridge and Fender Fat '50s neck pickup. TC Nova delay into a Reeves Custom 50.

mp3 Castellorizon - Buffalo TD-X. Strat with EMG-SA pickups and TC Nova delay into a Reeves Custom 50.

mp3 Fat Old Sun solo - BKB 911 Tube Driver. Strat with Seymour Duncan SSL-5 bridge and Fender Fat '50s neck pickup. Boss CS-2 > 911 TD > Future Factory delay > Ambi Space plate reverb into a Reeves Custom 50 into a Reeves Custom 50.

mp3 Fat Old Sun solo - Boss BD-2 Blues Driver. Strat with Seymour Duncan SSL-5 bridge and Fender Fat '50s neck pickup. Boss CS-2 > Boss BD-2 > Future Factory delay > Ambi Space plate reverb into a Reeves Custom 50.

mp3 Fat Old Sun solo - Past FX TD-Y. Strat with Seymour Duncan SSL-5 bridge and Fender Fat '50s neck pickup. Boss CS-2 > TD-Y > Future Factory delay > Ambi Space plate reverb into a Reeves Custom 50 into a Reeves Custom 50.

mp3 Take A Breath solo - BKB 911 Tube Driver. Demeter Compulator Compressor > TD > Future Factory delay > Ambi Space plate reverb

mp3 Take A Breath solo - Boss BD-2 Blues Driver. Boss CS-2 > Boss BD-2 > Boss CE2-B chorus (mix at 30%), Future Factory delay > Ambi Space plate reverb

mp3 Take A Breath solo - Buffalo TD-X. Boss CS-2 >TD-X > Future Factory delay > Ambi Space plate reverb

mp3 Take A Breath solo - EHX Hot Wax. Boss CS-2 > Hot Wax > Future Factory dela > Ambi Space plate reverb


You can read more about the Tube Driver HERE.

A list of the different versions of the Tube Driver can be found HERE.



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