THD Flexi-50 Instruction Manual
Contents
1. AY ON Bini 3 ERES T8138 h 20W STANDBY POWER aD De zs MH a 3 ante Hot Rod Flexi Input Hi Bright ON Master OFF Volume 1 00 O clock Boost ON Master Vol N A Treble Full Gain Full Cut Full Middle Full Tone Full Power Mode 50W Bass 10 00 O clock Notes Use your guitar s volume knob to control amp breakup For example to clean up the sound roll back your guitar s volume knob To get a thick hot rodded British distortion sound turn your guitar s volume knob completely up THD FT EXI 50 INSTRUCTION MANUAT P Flexi 50 Controls Front Panel First let s go through the various control options on the front panel 1 3 4 86 7 8 9 1 13 E i SEEE EE IU MO s P i p d 3 4 E A 1 Input This jack fits a standard 1 4 mono instrument cable If you use a stereo cable the sleeve signal will be ignored Do not use speaker cable into this input 2 Input Lo Hi switch This switch toggles the Input gain from low to high With the input on Lo sometimes called normal the input signal is not boosted You may prefer this setting for higher output pickups or less high gain tones Switching the input gain to High raises the input gain which boosts the volume of the pickup slightly You may prefer this setting for lower output pickups or to drive the Flexi input slightly harder The yellow LED above the Input jack will light when High gain mode is engaged 3 Volu2. FI EXI 50 INSTRUCTION MANUAT 4 Back Panel Now lets go through the Flexi s back panel jacks and controls 13 10 9 764 E M whe Lamm DE dae 1 Output jacks You can connect either one or two speaker cabinets to the Flexi using these two output jacks Only use speaker not instrument cable The outputs are wired in parallel so two 16 ohm loads result in an 8 ohm total load two 8 ohm loads result in a 4 ohms total load and two 4 ohm loads result in a 2 ohm total load 2 Impedance switch This switch allows you to set your Flexi for the proper impedance of your speaker cabinet load Most speaker cabinets and combinations of cabinets will use the 4 8 or 16 ohm setting However if you use 4 ohm loads you will find the 2 or 4 ohm setting to be slightly louder and has a bit more low mids Of course this side should be used for 2 ohm loads One of our innovations is that the Flexi always uses 100 of the transformer windings all of the time This assures you a full even output sound regardless of the impedance setting The power and output transformers are fully shielded to assure that hum and noise are kept to an absolute minimum and that pickup feedback from transformer coupling is all but eliminated 3 10K ohm Line Out jack This output jack delivers a line level signal from the power amp Use a 1 4 instrument not speaker cable with this output You can use this output to slave to another amp or to go direct to a mixing
3. THD FLEXI 50 d p L n INSTRUCTION MANUAL Thank you for your purchase of the THD Flexi 50 amplifier The Flexi 50 is a precision hand built 50 watt Class AB amplifier with foot switchable overdrive boost foot switchable master volume control and the ability to use almost any preamp and power tubes in any combination including 6L6 EL34 6V6 6CA7 8417 6550 KT66 KT77 KT88 KT90 KT100 EL84 with Yellow Jacket adaptor 6K6 6F6 12AX7 12AY7 I2AU7 12AT7 12AZ7 12DW7 12BH7 ECC83 ECC82 ECC81 and many more giving the user a huge pallet of available sounds simply by changing tubes The amplifier has a fat clear full clean sound reminiscent of late 1950s to early 1960s American combos and overdrive to rival the best British heads Even at the highest overdrive settings the amp still demonstrates dramatic touch sensitivity cleaning up very well when the volume on the guitar is reduced Additional features include external bias test points and individual bias controls permitting the user to quickly and accurately set the output tube bias with any digital voltmeter The dual bias controls permit the user to correctly bias even mismatched tubes eliminating the need for matched power tubes The unique combination of our touch sensitive input circuit and the wonderfully active and reactive tone control section that we slaved a year to perfect make for a front end that really responds to subtle and not so subtle changes in the s
4. console or recording system Keep in mind that you will need a speaker simulator in between the line out and your recording equipment if you want to record the Flexi from the line out When using the line out you must have a speaker or dummy load connected to the speaker outputs as the Flexi does not have a built in Hot Plate like the THD Univalve and THD Bivalve You may however purchase a THD Hot Plate set it to Load and then use the line out from the Flexi 4 Line out Level This control adjusts the output of the Line Out jack THD FI EXI 50 INSTRUCTION MANUAT 5 5 Line Out Switch Instrument Line This toggles the Line Out between 10dB instrument level output for use with guitar level signals or 4dB line level output for use into professional sound reinforcement or recording equipment 6 Master Connecting a 1 4 mono instrument cable between this jack and the THD Footswitch allows the THD footswitch to the toggle the Flexi s Master control 7 Boost Connecting a 1 4 mono instrument cable between this jack and the THD Footswitch allows the THD footswitch to the toggle the Flexi s Boost control 8 Switch Input with Boost This is another unique Flexi feature With this feature engaged the Input level is switched to High whenever you engage the Boost The effect of this is to make the boost effect a little more pronounced Engaging this control bypasses the front panel Input Lo High switch see Front Panel sectio
5. d socket for Tube 1 B THD FT EXI 50 INSTRUCTION MANUAT 9 4 Set your multimeter to read DC voltage If your multimeter requires you to set a DC Voltage range set it to the lowest single integer 5 With no input to the Flexi flip the Standby switch to Play 6 Using a flat blade screwdriver adjust the bias control for Tube 1 C turn it slowly the control is very sensitive If you are in 50w mode set it to 0 025 if you are in 20w mode set it to 0 017 7 Move the red probe of your multimeter from the Tube 1 socket B to the socket for Tube 2 D 8 Adjust the bias control for Tube 2 E the same way you adjusted the bias control for Tube 1 9 Leaving the red probe in the Tube 2 socket D move the black probe to the red socket for Tube 1 B If the two are power tubes are balanced properly you will get a reading of 0 00 10 If you do not get a reading of 0 00 in step 9 repeat steps 2 8 and adjust the tubes to identical values Keep repeating this step until the reading 1s 0 00 11 Play the amp for a while then repeat step 10 If the reading remains at 0 00 you re finished NOTE You won t need to rebias the amp if you are using EL84 tubes in the THD YJS or YJ20 Yellow Jacket adaptors as they are self biasing If you are using EL84 tubes in the THD YJUni Yellow Jacket adaptors you will need to set the bias since YJUni Yellow Jackets are for amplifiers that are already self biasing such as the THD UniValve a
6. ignal being fed into the amplifier either by the guitar or any effect that may be between the guitar and the amplifier THD FI EXI 50 INSTRUCTION MANUAT TABLE OF CONTENTS ISLC HOM yal occae neon E E E T O A TE AS 1 For People Who Hate Manuals Quick Start Setting ecce eee eee eee eene 2 HRONE im i en ee eee Z PICK 50 GC OMIT ONS NM H 3 8 010 cee E ee oe eee E 3 B du d ee re i ee UU 5 Example 5 CLC A E E E E E E E T E E 7 Ir ano MOO aeaa AEA A ETA E AEAT 7 ES CSS E o EE EEE E EEA EA 7 a Aa LY ASS E N E E N A E 8 Smoon Upper Mids oserei e 8 Soba S I T UT E E A 8 Biasing the Flexi 50 For Different Tubes 4 ee eee ee eene e eee ee eee e eee eene eeu 9 Power TUDES concede A E EE OE E MIDI IRI HN INE 9 Pieds EWC S ios osi E E DEMEURE 10 For People Who Hate Manuals Quick Start Setting We highly recommend you at least scan through the manual first to learn how the Flexi works If you are itching to get started now and will read it later here s a basic amp setting that will get you up and running Keep in mind the following conventions There are no numbers on the dials so knob positions are expressed in clock face notation e Full means that the knob is turned clockwise to its limit Sometimes referred to as dimed since it represents a value of 10 on numbered dials SOW PL
7. kup Smooth Upper Mids Input Hi Bright ON Master OFF Volume 1 00 O clock Boost ON Master Vol N A Treble 9 00 O clock Gain 1 00 O clock Cut 7 00 O clock Middle Full Tone 1 00 O clock Power Mode 20W Bass 3 00 O clock Notes Use guitar volume knob to control amp breakup Vintage Chime Input Hi Bright ON Master OFF Volume 3 00 O clock Boost ON Master Vol N A Treble Full Gain Full Cut Full Middle 2 00 O clock Tone Full Power Mode 20W Bass 7 00 O clock Notes Use guitar volume knob to control amp breakup THD FT EXI 50 INSTRUCTION MANUAT R Biasing the Flexi 50 For Different Tubes Power Tubes One of the Flexi s most exciting features is that you can very easily rebias the amplifier for new power tubes either of the same type or of different types The Flexi can be used with 6L6 EL34 6V6 6CA7 8417 6550 KT66 KT77 KT88 KT90 KT100 EL84 with Yellow Jacket adaptor 6K6 6F6 and any other derivations of the above tube types You can even mix and match different tube types together eliminating the need for matched pairs Rebiasing the Flexi is simple You ll need a digital multimeter and then just follow the directions below F on z gt 18 1o P 1 With tubes installed power up the Flexi Leave it in standby until the tubes have heated up at least two minutes 2 Insert the black probe of multimeter into the black socket A 3 Insert the red probe into the re
8. me This knob controls the input volume into the preamp tubes 4 Treble This knob can be used to boost or cut the high frequency response of the Flexi 5 Bright Switch If the bright switch is on an upper high frequency boost will be added to the signal This boost is independent of your Treble knob setting so you could for example set the treble knob to roll of the high end for a darker overall sound but turn on the Bright switch to add some upper brilliance 6 Middle The middle control offers a very musical mid range adjustment over a narrow frequency range 7 Bass This knob can be used to boost or cut the bass frequency response of the Flexi You ll find that the Flexi has bass to spare THD FT EXI 50 INSTRUCTION MANUAT 3 8 Boost Gain A special feature of the Flexi is that the boost circuit is voiced differently than the main channel so when the Boost circuit is engaged this control adds both an additional gain stage and a more British EQ voicing with thicker low and lower midrange frequencies 9 Boost Tone A unique Flexi feature is its full frequency sweeping Tone knob This control can completely change the texture and tone of the boost from dark and woody to searing and open 10 Boost ON OFF This switch engages or disengages Boost circuit The red LED above the Boost controls will light when the Boost is engaged The Boost can also be toggled with the included footswitch 11 Master The Master knob contr
9. n 2 9 FX loop Using 1 4 instrument not speaker cables you can connect line level 4 dB effects to the Flexi The FX loop is after the preamp section and before the power amp Connect the Flexi s Send jack to your line level device s input and your device s output to the Flexi s Return jack You can also use the send to connect the Flexi s preamp to the return of any other amp with an effects loop in order to use the preamp of the Flexi with the power section of that amp Keep in mind however that you must always keep a load attached to the speaker out of the Flexi 10 Bias Controls Basically these controls allow you to match the output of the Flexi to the tubes being used The main purpose of putting these controls on the back panel for you to access them easily 1s to allow you to change power tubes easily How to bias the Flexi using these controls is explained in the next section 11 Filament Power Fuse If you need to replace the Filament Fuse use a 6 Amp Slo Blo fuse only 12 HV Fuse If you need to replace the HV Fuse use a 1 Amp Slo Blo fuse only 13 Power Cable jack Use a standard universal V AC power cable with your Flexi 14 Mains Fuse If you need to replace the Mains Fuse use a 4 Amp Slo Blo fuse only THD FI EXI 50 INSTRUCTION MANUAT 6 Example Settings Now that you know what the controls on the Flexi do you re ready to go ahead and experiment with various settings In case you d like some example
10. nd BiValve amplifiers Preamp Tubes You don t need to rebias the amp to try out new preamp tubes just pull out the current tubes and inset a new one The Flexi can take any type of dual pentode preamp tube such as 12AX7 12AY7 12AU7 12AT7 12AZ7 12DW7 12BH7 ECC83 ECC82 ECC81 and more You can try any of the above tube types in any combination remember experimentation 1s the name of the game THD FI EXI 50 INSTRUCTION MANUAT 10
11. ols the overall output volume by limiting the amount of signal to the power amp tubes Some classic amplifiers did not have a master volume and their volume and gain were both a function of the single input volume The Flexi allows you to switch the Master completely out of the circuit to better emulate the signal path of those amplifiers 12 Master Switch This switch engages or disengages the Master control If the green LED above Master control is lit the Master is engaged The Master can also be toggled with the included footswitch 13 Cut This control functions much like a presence control in other amplifiers but with a significant difference A Presence control uses negative feedback from the amplifier to simultaneously adjust both gain and brightness The Cut knob on the Flexi adjusts the overall brightness but not the gain 14 50W 20W switch The 50W 20W switch toggles the Flexi s plate voltage to the power tubes from 475v 50W to 325v 25W Lowering the Flexi s plate voltage both reduces the volume of the amp slightly and changes its character In 50W mode the Flexi is slightly tighter and more aggressive in 20W mode it is a bit warmer and smoother 15 Standby Switch Standby mode keeps the power tubes powered and the amplifier itself off Always power up in Standby mode and allow the tubes to heat up for at least two minutes before switching to Play 16 Power On Off The Power switch turns the amplifier on or off THD
12. settings as launching points for your own explorations here are some settings contributed from experienced Flexi users As mentioned in the Quick Start section above please keep the following conventions in mind There are no numbers on the dials so knob positions are expressed in clock face notation e Full means that the knob is turned clockwise to its limit Sometimes referred to as dimed since it represents a value of 10 on numbered dials Dark and Smooth Input Lo Bright OFF Master OFF Volume 3 00 O clock Boost OFF Master Vol N A Treble 8 00 O clock Gain Full see below Cut Full Middle Full Tone 12 00 O clock Power Mode 20W Bass 12 00 O clock Notes To switch between this dark and smooth setting and a punchy tone with rich breakup turn on the Switch Input with Boost switch on the back of the Flexi Less Compressed Input Hi Bright OFF Master OFF Volume 2 00 O clock Boost ON Master Vol N A Treble 12 00 O clock Gain Full Cut 3 00 O clock Middle Full Tone 3 00 Power Mode 50W Bass 10 00 O clock Notes Turning the Treble to full and the Cut down thickens the sound THD FT EXI 50 INSTRUCTION MANUAT 7 Heavy Bass Input Lo Bright OFF Master OFF Volume 1 00 O clock Boost ON Master Vol N A Treble 3 00 O clock Gain Full Cut 11 00 O clock Middle 4 00 O clock Tone Full Power Mode 50W Bass 3 00 O clock Notes Use guitar volume knob to control amp brea
Download Pdf Manuals
Related Search