Corvair - Aiken Amplification
Contents
1. 1 Megohm lt 1mV for full clipping channel 2 Four 12AX7 ECC83 preamp tubes two 6V6 power tubes 100V 120V Mains 2A slo blo HT 500mA fast acting 200V 240V Mains 1A slo blo HT 500mA fast acting Head 17 75 W x 8 H x 8 75 D 20W head TBD2. Y cables for the extra two cabinet connections Be sure to use only quality speaker cable do NOT under any circumstance use guitar cable to connect the amplifier to a speaker cabinet Doing so may cause damage to the amplifier Effects Loop Midi There are two standard style jacks for loop send and return The FX Level switch allows the choice of either 4dBu line level pro effects for lowest noise levels or 10dBV instrument level effects like standard foot pedals to be used in the loop Once properly connected adjust the effects unit s input level control so the signal presence LED is lit if there is one and the clip LED occasionally lights on peaks or doesn t light at all depending on the effects requirements Then adjust the effects unit s output level so the Tempest s volume is the same with loop on or off Refer to the effects unit user manual for proper adjustment in case it differs from these instructions All switchable controls can be changed via MIDI commands There is a MIDI in and MIDI through jack 12V 1A power is available on the MIDI IN jack to power a MIDI footswitch or controller Tube layout and replacement a ke 0 real 12AX7 ECC83 0 Oo 6V6 6v6 qI 12AX7 ECC83 12AX7 ECC83 12AX7 ECC83 The Corvair uses four 12AX7 ECC83 tubes and two 6v6 The chassis top view layout is shown in the diagram above The preamp tubes are housed in removable bayonet
3. inrush current when the amp is first turned on and they are fully discharged and this can occasionally cause a fuse to blow particularly if the fuse is old If your amp blows a fuse you should replace it with one of the same type and rating If it still blows the fuse the amp needs further servicing The HT fuse should be a fast acting type and the mains fuse should be a slo blo type If your Corvair blows the HT fuse it is most likely caused by a bad output tube or incorrect bias setting usually accompanied by red glowing plates in the tubes and a very hot running amplifier If it blows the mains fuse immediately on power up every time it is most likely a bad rectifier diode If it just occasionally blows the mains fuse you may want to go up one size in fuse to prevent this nuisance blowing If you are using a 2A fuse try a 2 or 3 amp fuse but don t go any larger or you may damage the power transformer in the event of a real failure Troubleshooting steps 1 First pull out both output tubes and put in a new fuse Turn the amp on If the pilot light comes on the power transformer and wiring and rectifier diodes are fine Let it run for a few minutes to make sure the fuses don t blow again Then proceed to troubleshooting step 3 2 If the mains fuse blows immediately upon power up you likely have blown rectifier diodes These can easily be replaced by any competent technician The Corvair uses 1000V 3A FR307 fast re
4. Corvalir User s Manual Revision 1 0 Aiken Amplification Inc 1410 Hwy 72W Greenwood SC 29649 Tel 864 993 6348 http Awww aikenamps com Contents CONTESTS isin sss esses eet cin secon acti cea cote E aby an see EE 2 Getting Started aaan aaia AARE ia aadar inaidai idia iie 3 Front Panel Controls and Switches cccccccccccseeeseseeeensesesnnesnennsnnensennsnnsnsenes 4 Rear Panel Controls and SWItCheS cccccecesceccecceceeeeeennnsenseseeeeeeeeennessseeeeeneees 7 Tube layout and replaCe ments iscsicccicececevesecesedticrisevinosecexixudeccosntateouvatnteiavacietes 10 VIE Iae EEEE EEE ATE A E E EAE ET E AE 11 TE C E E tateneentre memes 12 TAIT ILa Loola a19 AEAEE E E EE EE E E E E 13 SDC CINIC ATION e A EEEE EEE AE E E A ET 17 Getting Started Congratulations on purchasing your new Treble and Master controls with a Aiken Corvair amplifier Presence and Depth control as well as an effects loop With the Talent switch s three The Corvair is a 20W single channel midi gain levels this amp goes from classic programmable amplifier featuring two 6V6 crunch to over the top sustaining distortion tubes in the output stage The single high almost like having a three channel amplifier gain channel features Gain Bass Middle Features include e All tube signal path Preamp tubes are 12AX7 ECC83 Output tubes are 6v6 The rectifier uses massive 3 amp 1000V ultra fast recovery diodes Ultra FREDs for utmost reliab
5. ach side of the stage fills up the tone very well and provides an almost stereo like sound field because of the cancellations that occur when standing in different places on stage The Greenbacks are the recommended speaker for 2x12 and 4x12 cabinets for the classic vintage tone When changing speakers always insure that the output impedance selector is set to match the impedance of the speakers connected to the output jacks The Corvair has two paralleled output jacks and can easily drive two 4x12 cabinets to extremely loud volume levels despite the 20W rating Troubleshooting Pilot lamp not lit Is the amplifier plugged into a functional outlet of the appropriate voltage Is the mains fuse blown If so replace with the appropriately rated fuse If the fuse again blows the amplifier may have a shorted output tube or rectifier tube Replace the tubes and fuse and power the amplifier up again If the fuse still blows the amplifier will need to be serviced Pilot lamp lit but no sound low sound or intermittent sound Is the HT fuse blown If so replace with the appropriately rated fuse If the fuse again blows the amplifier may have a shorted preamp tube output tube or rectifier tube Replace the tubes and fuse and power the amplifier up again If the fuse still blows the amplifier will need to be serviced Is the speaker functional and plugged in correctly Insure the amplifier s output impedance selector is correctly set to
6. covery rectifiers available online from Digikey at http Awww digikey com but you can substitute standard 1N4007 diodes if necessary For added protection against future rectifier failure due to voltage surges use two diodes wired in series in place of each of the diodes this is addressed in service bulletin 2 Be sure to replace all the diodes not just the bad one in case the amplifier was subjected to a voltage surge which may have marginally damaged one of the other diodes There is a small chance fuse blowing can be caused by a bad filter capacitor or power transformer but this is highly unlikely unless the amplifier is very old or has been subjected to misuse line voltage surges or incorrect setting of the mains voltage switch 3 Next install the power tubes If the fuse blows one of the output tubes is bad and the entire set should be replaced If the fuse doesn t blow and the amp works fine it was likely just a nuisance fuse blowing and the amp should be monitored carefully for the first hour or so of playing just to make sure everything is okay Never keep feeding fuses to an amp that is blowing them you ll likely cause permanent damage Stop after the second one blows unless you ve isolated the cause as I ve described it above Specifications Output Power Input Impedance Input sensitivity Tube complement Fuses Dimensions Weight 20W RMS at onset of clipping into resistive load at rated impedance
7. e stopped by tightening the screws a small piece of double stick tape affixed to the rear of the nameplate will dampen the vibration Some speakers are known to exhibit cone cry or ghost noting which is a second out of tune note that occurs only when playing certain notes on the guitar If this is suspected try another speaker to see if the problem goes away Hissing noise A small amount of hiss is a characteristic of high gain tube amps and is generally unavoidable Excessive levels of hiss are usually caused by bad preamp tubes Some preamp tubes have more hiss than others Try replacing the preamp tubes with different ones to see if the hiss decreases Ticking noise Some tubes particularly JJ ECC83 tend to exhibit a low level ticking noise right after the amplifier is taken off standby The noise stops after a second or two when the tube has had a chance to stabilize and is not indicative of a problem Ringing noise or feedback that occurs with no guitar plugged in If the amplifier exhibits a ringing noise especially when tapping on the chassis or if it makes a howling or whistling feedback noise when the volume is turned up but no guitar is plugged in there is probably a microphonic tube in the amplifier likely in the first position the small tube closest to the input jacks or in the reverb recovery position Remove the shield and lightly tap on the tube with the volume turned up A small amount of noise is n
8. igned to create Celestion Greenbacks have less volume and a dip in the mids which makes them nice and smooth The amplifier was voiced for this speaker in a 4x12 cabinet or a 2x12 cabinet They are rated at 25W so they make a good match for the Tempest in a 2x12 or 4x12 cabinet Celestion Vintage 30 s have a very pronounced midrange which may be a bit too harsh in an open back configuration which naturally enhances the midrange frequencies and can sound a bit boxy with the wrong speaker They do sound good for some blues and rock styles and can easily handle the power of the Tempest in a 1x12 configuration Celestion G12H30 s are like a cross between the Greenback and the Vintage 30 with more low end than the Vintage 30 and not quite as pronounced a midrange so they tend to sound subjectively better in an open back cabinet Eminence and Warehouse Guitar Speakers also make some very nice British and American voiced speakers Your mileage may vary Closed back cabinets have better and tighter bass without the pronounced midrange hump of the open backs but they don t disperse on stage as well and tend to be beamy sounding very loud out front but if you stand above and to the front or back you can t hear yourself as well Still there is nothing quite like the tone of a cranked up 4x12 cabinet loaded with Greenbacks Fora more portable closed back a 2x12 loaded with either of those Celestions will do the trick nicely Putting a 2x12 on e
9. ility and a tight low end without the RF noise interference spikes inherent in standard rectifiers e Front panel controls connections Input jack Gain Treble Middle Bass Master and Presence and Depth as well as the Talent switch Voicing switch Solo switch and the effects loop switch and mix control e Rear panel controls connections AC mains input 1 4 speaker jacks and midi connections to control the programmable functions There is a two level 4dBu 10dBV effects loop using two 1 4 jacks for send and return and a push button switch to select the level Also included is a speaker emulated XLR direct output e Solid dovetail jointed void free birch ply cabinets The head cabinet is 17 3 4 wide 8 tall and 8 3 4 deep e Hefty 16 gauge steel chassis zinc plated yellow chromate conversion coated for durability corrosion resistance and appearance Front and rear faceplates are black anodized aluminum for a durable classic look e High quality carefully engineered PC board construction using modular design techniques for ease of maintenance quiet operation and reliability Built to last and if service is ever needed removing and replacing boards is very easy You don t even have to send the amp in for service we can diagnose the problem and send out a replacement board right away no special tools or skills are necessary to replace a board e Premium tight tolerance parts are used for lowest noise operation
10. in to the amplifier The solution is to use a ground loop hum eliminator there are a few on the market or make a guitar cord with a telescoping shield to go from the output of the effects to the input of the amp This is a cord with the shield cut on one end The cut end should go into the amplifier input jack and the end with the shield must go into the output of the effects unit tuner In a emergency a ground lift plug three prong to two prong adapter can be used on the tuner effects box but this is not recommended due to safety concerns If you do use a ground lift adapter you should check to see if there is any AC voltage present from the chassis of the rack effect tuner to the chassis of the amplifier If so do not use the adapter If the buzzing only occurs when playing the guitar try replacing the speaker or plugging the amplifier into an extension speaker cabinet A buzzing noise from the speaker can indicate a blown speaker or one with a warped frame Buzzing noises that occur only on certain notes can be indicative of a cabinet problem Check all rear panel screws handle screws and chassis mounting screws to insure they are tight Check to insure there are no speaker or reverb cables rattling against the baffle board Check the two screws that hold the nameplate to the front of the amplifier as the nameplate can cause a rattle or buzz if it is loose enough to vibrate against the front panel board If the nameplate buzzing cannot b
11. including 1W and 2W carbon film and metal film resistors where appropriate for best tone and lowest noise SW metal oxide power resistors and radial leaded film capacitors CorvairManual doc 05 10 14 Page 3 of 14 Copyright 2014 Aiken Amplification Inc Front Panel Controls and Switches Input jack Plug your guitar in here and you are ready to rock Talent switch This push button switch sets the overall gain which is indicated by the color of the LED Green is least gain yellow is medium gain and red is highest gain The talent switch can also be thought of as a two stage gain boost where green is normal yellow is boost level one and red is boost level two For simplicity of programming the setting of the talent switch is automatically saved to the midi channel you are currently on Voicing Switch Gain Treble Mid This pushbutton switch selects between three midrange voicings green yellow and red The voicing changes are not drastic but allow you to tailor the midrange a bit to your liking This control sets the amount of gain relative to the talent switch setting For the cleanest possible tone set Talent to green and turn the gain control down For the most sustain and distortion set Talent to red and turn the Gain control all the way up This control adjusts the high frequency equalization of the preamp This control adjusts the midrange frequency equalization of the preamp Bass This con
12. match the speaker in use Is the guitar cord functional Bypass any pedals and plug straight in with a known good cable to test Is the effects loop jack dirty or broken Try turning the loop off via the front panel pushbutton switch No effects loop operation Are the cables fully plugged into the jacks on the back of the chassis Is the effects unit designed for pro level OdBu nominal 4dBu max or instrument level 10DbV levels and is the rear panel 4 10 switch set accordingly Is the effects unit in bypass mode Does the signal presence LED if there is one on the effects unit light when you hit a chord Is the signal clipping LED if there is one on the effects loop illuminated Humming or buzzing noise Unplug the guitar cord from the input and unplug any cable used for jumpering the two inputs If the buzzing stops try replacing the cord Be sure to use only guitar cables not unshielded speaker cables If in doubt unscrew the connector and look to see if there is a shield around the center connector Some smaller speaker cables are easily mistaken for guitar cables Fluorescent lights and light dimmers can be a source of hum buzz as can computer monitors If the buzzing only occurs when using effects or a tuner the problem is likely a ground loop hum in particular the Korg rack mount tuner seems to be susceptible to ground loops If this is the case the hum buzz will go away if the guitar is plugged straight
13. metal shields The shields can be removed by pushing down on them and rotating the shield to the left then pulling it upwards off the tube The tube can then be pulled out of the socket Note vacuum tubes especially output tubes can get very hot in normal operation and may cause burns if removed before they have a chance to cool down Be sure to wait several minutes before replacing tubes to allow them to cool down Do not under any circumstances remove or replace the tubes with the power on as this could cause a deadly electrical shock should the glass break exposing the high voltage plate terminals Also be sure to pay attention to the orientation of the tubes when putting them back in the socket The tube pinout is keyed so it can only be placed in the socket in one direction and if the tube is forced in incorrectly it can damage the tube or the socket The octal output tubes have a phenolic key that fits a corresponding keyhole in the socket If this key is broken off it will allow incorrect placement of the tube in the socket which could result in damage to the amplifier Be sure to carefully examine the tube before replacing it Biasing TBD Speakers Changing speakers is like getting a whole new amp Every model sounds completely different some sounding quite good and some amazingly bad The amplifier is particularly suited for use with Celestion loudspeakers which give the characteristic British sound this amplifier is des
14. on This sets the wet dry mix of the effects loop when in parallel loop mode Power switch The Power switch turns the amplifier on in the up position and off in the down position The integrated pilot lamp lights when power is applied to the amplifier and the power switch is on Glory switch What good is power without the glory The Glory switch allows muting of the amplifier output when not in use When the switch is in the up position the amplifier is on and when it is in the down position the amplifier is on standby The tube filaments remain on and warmed up so the amplifier is ready to play as soon as it is taken off standby The correct powerup sequence is to turn the amplifier on with the power switch and then after it has had time to warm up the Glory switch is turned on When turning the amplifier off the Glory switch should first be turned off then the power is turned off after a few seconds Rear Panel Controls and Switches Mains Input Plug the supplied IEC mains cord into this outlet to provide power to the amplifier Mains Fuse 2A slo blo for 100V 120V operation 1A slo blo for 200V 240V operation Speaker Jacks Five speaker jacks are provided 2 16 ohm 2 8 ohm and 1 4 ohm to allow use of the amplifier with either the internal speaker combo units only or up to two external speaker cabinets More than two external cabinets may be safely used with the amplifier but this will require the use of
15. ormal but a loud ringing noise indicates a microphonic tube which should be replaced In a emergency you can swap the other 12AX7 ECC83 preamp tubes around until you find the least microphonic one to put in the first position Typically the phase inverter tube is the least susceptible to microphonics so the most microphonic tube should be used in this position The least microphonic tube should be used in the first position and the next least microphonic tube should be used in the reverb recovery position When purchasing tubes be sure to purchase tubes that have been tested for microphonics Many vendors do not test for microphonics and you could end up wasting your money on tubes that are unsuitable for use Combo amps are more susceptible to microphonics than heads because the sound field coming from the back of the speaker can excite the tube into oscillation In rare cases the 6V6 output tubes can be microphonic particularly if they are at the end of their lifespan Fuse blowing An amplifier typically has two fuses one for the mains or AC supply and a second one for the HT or high voltage section of the amplifier It is perfectly normal for a blown mains fuse to shut the entire amp down That s the fuse s job to shut the amp off to protect it in the event of a short circuit Sometimes a fuse will blow for no apparent reason called nuisance fuse blowing An amplifier has large filter capacitors that can draw quite a bit of
16. trol adjusts the low frequency equalization of the preamp Presence Depth Master Loop Solo FX Mix The presence control adjusts the high frequency equalization in the output stage It is a shelving control that operates by cutting the amount of high frequencies in the global negative feedback loop which results in a boost in the output high frequency range and a subjectively brighter and more open tone in the highs due to the lower negative feedback at those frequencies The presence control frequency range is higher than most presence controls and is primarily designed to add sizzle to the distortion channel acting as a fourth eq control voiced above the treble control range The Depth control adjusts the low frequency equalization in the output stage by cutting the amount of low frequencies present in the feedback loop thereby boosting the low frequencies in the output for more bottom end This control sets the overall volume of the amp This switch allows you to choose between a series effects loop a parallel effects loop or effects loop off The LED will be red for series loop green for parallel loop and off for loop off The setting will be automatically saved to whatever midi channel you are currently on This switch adds a clean volume boost to your signal generally for a louder solo volume without added distortion The setting will be automatically saved to whatever midi channel you are currently
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