Transcript
SOUL-O SERIES 75/150 OPERATING MANUAL 9 - There is no particle board in any part of our cabinetry, only solid core American plywood. Of course these features and construction details cost more, but you can really hear the difference! The Front Panel Features... The Preamp Stage The Soul-o Series preamp stage has 5 GT12AX7 dual triodes, each performing multiple functions in the circuitry. The two channels are designed with entirely different purposes and therefore have vastly different gain structures and voicing. You may switch between Clean and Scream, or combine them as Both for more really interesting possibilities. These can be switched from the front panel or by the optional footswitch, in which case the front panel switch must be in the center, or Both, position. It is also possible to adapt the footswitch jack to work with most remote rackswitching devices.
Congratulations, you’ve just purchase what we believe is the best amp on the planet! We’d like to welcome you to the growing list of artists who share our mutual lust for tone. Now, we’d like to better acquaint you with your Soul-o amp new amp and show you how to get the most out of this incredible hand built tube amplifier. Some of our unique construction details: 1 - All components are hand soldered. There are no quick disconnects, wire nuts, or dipped connections and over 120 hand soldered connections on the tubes sockets alone 2 - All transformers are custom designed and made exclusively for Groove Tubes. 3 - GT amps are designed to use your choice of 6L6, 5881, European E34Ls or KT88s power tubes. Choose from a total of 13 different tubes which are currently available from our GT catalog. Customized your S75 for tone and power from 35 RMS watts to 95 RMS watts, and the S150 from 80 RMS watts to over 190 RMS watts! 4 - The entire amp chassis for the combo package is shock mounted on rubber isolators to reduce adverse interactive vibrations and microphonics at higher playing levels. 5 - The critical V1 preamp tube is also shock mounted on a special rubber isolator to reduce adverse interactive vibrations and microphonics at higher playing levels. 7 - We use only double sided, double thick PC boards with double thick traces and no PC mounted sockets. Instead we use chassis mount type sockets bolted and hand wired to the PCB. This is the best of both worlds; PCB and point to point construction. 8 - There are more than 28 hours of hand labor in each Soul-o Series amp. Each amp is custom to built to order!
The Clean Channel has the basic 5 controls you’ve likely seen before: Gain; Bass; Middle; Treble; and Volume plus a Brite switch for that real “cutting edge” sound. You may want to turn the Brite switch off if you’ve got a Telecaster. The Clean channel is not designed to produce heavy distortion, hence it’s name. However, an increase of Gain and decrease of Volume will produce a gradually fatter, warmer tone while the opposite will produce the brightest sound and most dynamics or headroom.
The design of the tone controls on this channel are passive, as used on older style amps. Active designed tone controls, most common in newer amps, have a separate gain section for each tone band, in effect they act like a series of effects loops which “suck tone”...so we don’t use them. Our tone controls are more interactive with your style of playing and are simply more musical. To get the most out of passive tone controls, start by listening to the channel with all tone controls at the 12 o’clock position. Then, if you want more bass, either: 1) crank up the Bass control; or 2) lower the Treble control, raising the gain to compensate the volume loss. Passive controls are interactive, so turning any one of them fully on, or off, diminishes the effect of the others and alters the gain structure. Experiment with this advice in mind. The Scream Channel The Scream Channel also has the same basic 5 controls plus a Fat switch, which does just what is says. However, since this channel is designed to produce a wide range of distortion tones from Blues to Metal...the Gain and Volume ratio are everything! If you want more distortion, raise the Gain and lower the Volume. This channels tone controls are also passive, but of a different design than the other channel. This tone circuit is called a cathode follower type and changes it’s tone depending on how hard you pick the string of your guitar. Notice as you push the note harder with your
playing, the tone will brighten up, while softer playing will produce a rounder fatter tone...that is by design and will give you a truly touch sensitive channel that will reflect your personality...indulge yourself and have some fun! Remember, as with all passive type controls, start with them in the 12 0’clock position and season to taste from there...don’t just crank them all up and wonder why the channel sounds mushy! CAUTION: The Scream channel uses passive tone control circuitry for the most musicality and also has tremendous available gain because we do not know if your guitar would have low or high output pickups. Therefore, we wanted to provide enough gain so that even a very low output pickup can achieve excellent overdrive distortion and sustain. However with stronger pickups, and with the Gain or Treble controls at higher levels, it could be possible to induce self-occilation in the Scream channel, or make it scream all by itself. If this should occur, simple lower the gain and/or Treble control to acceptable levels. Using Both Channels Another unique feature of this amp is that Both channels can be used at the same time. Simply select the Both position on the front panel (and/or the Both position on the optional footswitch) and Clean with Scream can now be balanced using their separate Volume controls. I have found that the most useful gig setting is to simply find my optimum Clean; channel setting, then find my best Scream channel setting and when I switch into Both, the sound is perfect for the “second” lead tone or a great third tone with my guitar volume backed slightly down. It’s a great feeling playing with the fat, compressed Scream channel coupled with the edge and full voice of the Clean channel underneath...it’s a great tone! Note, when using the footswitch: to get back to the alternating Scream/Clean mode, you must de-select the Both position from the footswitch. Once the Both position is turned on, it must be turned off! The Presence Control This control is interactive with the power stage, and when you increase it’s level you are adding more high frequency back into the feedback loop of the power tube stage. Increasing Presence will increase the interactive gain and provide more touch and push in the amp. Normally, I use the same settings for the tone controls and adjust the Presence for the gig I’m playing. More Presence for an acoustically “dead” room, and less for the “more lively” rooms. Also, perhaps you might want to use less on a single coil guitar and more on a humbucker type. The Rear Panel Features... The most unique rear panel feature are the switches that select the circuitry for using the power tubes. You may select between Class A/B, Class A Normal, and Class A Gnarly. We developed this design from 18 years of experience with the many vintage amps from the GT collection. Some great sounding amps like the Vox
AC30 used Class A circuitry as did early Tweed Fenders. More modern Fenders and Marshalls used the power tubes in a Class A/B circuit design. Frankly, we liked both designs and invented a way to switch between them. In addition, we developed a special output transformer designed to work with many different types of power tubes. The combination of these unique power section designs give the player ultimate flexibility in customizing the tone, power, and response of his power stage. The Power Amp Stage All Soul-o Series stages are designed to use many types of power tubes, up to 13 different types that are currently available from our Groove Tubes catalog at the time of this writing (and more are coming in the near future!) This allows you to “customize” your amp for the style of music you’re playing, and also to dramatically change the power, tone or response of your amp when the urge hits. Also, our unique output design allows the tubes to be used in three basically different circuit designs which can be manually selected on the rear of your control panel: 1) Class A/B, commonly referred to as Push/Pull, where the power tubes work in an alternating system which provides maximum power and more dynamic range. This design is common to almost all newer Fender or Marshall type amps and is favored by modern amp designers because it produces maximum power from the output tubes....more bang for the buck! 2) Class A Normal which emulates early Fender amp designs (pre 1954) where the power tubes work in unison and so lose about 30% of possible output power and produce more compression. Another trait of this Class A design is that the tubes draw full current at all times and so run hotter (Class A/B draws current only on demand; no signal from guitar, no power draw and so the tubes run cooler). 3) Class A Gnarly a slightly less efficient form of Class A which produces about 10% less than the Class A Normal design. This circuitry emulates the early Vox AC30 amp tone and is even greasier sounding and more compressed. Switching between the circuit designs Located on the rear panel, the the left switch selects “Class A/B in the up position and Class A in the down position. The right switch selects between Class A “Normal” and Class A “Gnarly” and is active only when the first switch is in the Class A position. The amp does not necessarily need to be put into “standby” mode before switching between output tube designs, but it is highly recommended to avoid a loud popping sound in the speakers. NOTE: Power tubes react in various degrees to these different circuitry designs. The most dramatic differences between Class A and Class A/B seem to occur with the 6L6 type tubes, and less so with the EL34 type tubes.
“Tone Tips” for tubes and output stage options • Gritty, greasy old AC30 tone, but louder, try using EL34’s in Class A Gnarly. Estimated power from the S75 ranges from 50 to 55 watts depending on EL34 type used. • Warm & bouncy round old Tweed tone, try any 6L6 type tube in the Class A Normal mode. Estimated power output of a S75 ranges from 45 to 55 watts depending on 6L6 type used. • Newer, tighter, cleaner Blackface Fender tone, try any of the 6L6 types in the Class A/B mode. Estimated power output of a S75 ranges from 55 to 70 watts depending on 6L6 type used. • Dynamic Metal punch or crunch tone, try a EL34 type, or better yet the newly developed, high powered GT E34Ls in the Class A/B mode. Estimated power output of a S75 ranges from 65 to 75 watts depending on EL34 type used. • Steel clean, ball peen hammer tone, try the KT88s tubes in the Class A/B mode and plug in your Telecaster with the bridge pick up...you’ll think you’ve died and gone to hillbilly heaven! Estimated power output of a S75 ranges from 80 to 95 watts depending on KT88/6550 type used. Note: The S150 amp this can produce over 190 watts RMS...and can easily damage hearing. So be careful not to stand directly in front this amp connected to one of our EX412 cabs....you have been warned! Speaker Impedance Selector The GT custom designed output transformers not only work with many types of power tubes, but also have multiple secondary windings that allows for selection between 4, 8, and 16 ohms speaker loads. These features allow you to customize your amp and speaker combination to emulate virtually any classic amp example or invent new combinations. We believe in the philosophy to customize, and not modify, the basic components of the amp and thereby give the owner the ultimate in flexibility. As his or her musical tastes and needs change through the years, the Soul-o Series amp can evolve with them. CAUTION: Always use the #1 speaker jack. The #2 is only for adding a second speaker. The #1 jack has shorting circuitry which turns the amp off if there is no speaker connected. Also, the total load of one, or both speakers should correspond with the speaker impedance selector.
The Parallel FX Loop This is the most tonally transparent FX loop you have ever heard, IF you learn to operate it correctly. When properly set up, this loop allows you to use any digital or analog FX unit blended in parallel with your original dry preamp signal without any sacrifice of tone...which is the case when using a conventional FX loop. That’s because most guitar amp FX loops are Series types, so the FX are placed “in series” between the preamp and power stage. In this design, a relatively powerful tube preamp signal enters the input
stage of the FX unit and has it’s level greatly reduced so as not to overload the FX units low energy chip. After the processing is completed by the chip, the signal strength is returned by a transistor. So now the nice, fat tube preamp tone is converted to a thin, wimpy transistor tone. We call this “the tone sucking transistor FX syndrome”...and we designed a system that cures it! Our approach is to use two signal paths that are mixed on the rear panel via the Mix control. Usually, you would mix the dry/wet level on your FX unit, but for best result with our loop you will now want to set you FX unit for 100% Wet and 0% Dry. The Send level would normally be set fully up, unless you are using a low signal level device such as a foot pedal in which case you might overdrive the FX unit unless you lowered the send level. Use the Return jack for the output of the FX device, and the Mix control to blend in the desired level of FX. The secret is to have the Mix level set with 98% Dry signal from the internal Soul-o preamp stage blended with a 2% very Wet FX level (see photo above). This should give you loads of FX, while letting the original preamp signal pass unaffected by the transistor tone stage of the FX device. When using the optional footswitch, you should be able to turn the Loop off and on without any change in tone...it should be absolutely transparent when set up in this manner. For some real flexibility, try inserting a normal foot controlled volume pedal between the FX return signal path. Now when you increase the volume controller the FX will gradually come on or off as you like, leave the loop selector of the footswitch in the “on” mode and simply use the pedal to turn your FX unit on or off, or anywhere between!
Other Soul-o Series Options The S75RM and S150 RM (the RM stands for “Rack Mount”) amps can be inserted directly into your rack system. They may also be built into various wood cabinets and coupled with various GT speaker cabinet to make really great sounding, traditional looking amp. Here are some of the cabinets and accessories you may want to consider to customize your Soul-o amp to your specific needs. It should be noted that all Soul-o cabinets are constructed of interlocking lightweight plywood that is braced, power nailed, and glued. The cabinets are then covered in US made heavy Tolex material. S/FS: A matching footswitch that selects between Clean and Scream, selects Both (on or off), and turns the Parallel loop on/off. LED lights indicate the status of the various selections and it comes with a 25’ cable terminated in a 5 pin Din connector that connects to the rear panel of the amp. Cage: A metal cage used to protect the tubes. Commonly used if the amp is to be freestanding, say on top of a recording console. Strong enough to have 4 rubber feet attached to the top/bottom of the cage
RF1: A specially made rack fan panel that locates a two speed fan adjacent to the power tubes which exits the heat from the tubes thereby prolonging tube life and reliability. Also has 2 extra AC sockets for Rack effects. Highly recommended for Class A operation and is included in both the popular Combo Package and Top Package.
The Separate Speaker Cabinets Our special designed cabinets are tuned for guitar playing and made fundamentally different than any other commercially available cabinets on the market. We use a lighter weight 5/8” baffle board and slant it upward on an angle for better projection. EX112: A matching cabinet that houses one 12” speaker. Available unloaded or with our own design Classic Clone 12” speakers, the CC112/A made in America by Eminence or the CC112/B made in Britain by Celestion. EX212: A matching cabinet that houses two 12” speakers. Available unloaded or with our own design Classic Clone 12” speakers, the CC112/A made in America by Eminence or the CC112/B made in Britain by Celestion. EX410: A matching cabinet that houses four 10” speakers, available unloaded or with our own design Classic Clone 10” speakers made in Britain by Celestion. The Custom Color Options The standard color for GT cabinets is Black Tolex with Tan grill. Various other colors are available such as Brown, Cream, Red, Purple, Cowboy Bob Black (the hand tooled look), Ostrich and Boa. Also, special material coverings are available on request such as leather and cowhide.
SC112: A combo box with a mounting for a 12” speaker, a rack fan panel, and room on top of the amp for a single rack FX unit to be mounted to the amps rack ears via a small piece of rack rail. This cabinet is designed to hold the Soul-o amp on 4 special rubber isolators to eliminate interactive microphonic resonances caused by the speaker at higher playing levels. NOTE: When you’ve ordered a Combo Package Soul-o amp, we pack your amp for shipping using two small wood screws into the side rack mounting rails to stabilize the amp so it will not damage itself in shipping. You should immediately remove these screws so the amp can float free on it’s rubber isolators. Also, the power tubes will be removed and packed in a special material so they will not become damaged in shipping. Remove these tubes and carefully insert them into the tube sockets behind the rack fan panel, with the GT logos facing outward. SC112-3: Same as SC112 but has 2 extra rack spaces above the amp. SB: A simple box housing just the amp and a RF. SB2: Same as SB but with one rack space above the amp.
Groove Tubes
Specifications: Input Input Level FX level Preamp tubes Power Output S75 amplifier Class A/B mode
S150 amplifier Output design
Speaker loads AC requirement H.T Fuse AC Fuse Chassis Weight
1/4 “ phone jack -10 dB nominally -10 dB nominally (5) GT12AX7 (also GTECC83 & GT7025)
GT6L6A = 60wt, GT6L6S = 70wt GT6L6C = 55wt, GT5881A = 65wt GT KT66R = 62wt, GT6L6R = 55wt GT EL34R = 70wt, GTEL34C = 70wt GTE34Ls = 75wt, GT6550C = 75wt, GT6550R = 80wt, GTKT88C = 75wt GTKT88s = 95wt Roughly double the S75 as shown above Class A/B = full power output Class A Normal = 30% less than Class A/B Class A Gnarly - 35% less than Class A/B 4, 8, or 16 ohms Wired internally @ 100, 120, 220 or 240 VDC 1 Amp Slo-Blo S75 @100-120VAC = 3Amp Slo-Blo S75 @ 220-240 VAC = 1.5 or 2 Amp Slo-Blo 14 gage welded steel, hard chrome plated S75RM = 24 lbs.; S150 RM = 27.5 lbs. S75 Combo Package = 70 lbs. S75 Top Package = 50 lbs.
LLC
1543 Truman Street, San Fernando, CA91340, (818) 361-4500, fax 365-9884
www.groovetubes.com
