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Smart Altering Guitar Electronics
S.A.G.E. |
INTRODUCTIONGuitar electronics at all simplicity – is an artful thing enough. In overwhelming majority of cases «passive electronics» is used by checked up by decades. Term «passive» means when no power supplies and no active elements (transistors, OP-AMP, etc.) are used in the guitar. There is lot of people who are admirers of such circuits. Many of thus consider, that only this method it is possible to receive «the true guitar sound». And it is not simple words, since there is huge quantity of examples of fine «passive» guitar sounding. But still active electronics - draws attention of guitarists. For many different reasons - it would be desirable to raise a level of a signal (and may be correct some), to reduce the influence of a cable, to lower a level of noise and external buzz. Frequently for this purpose guitarists try to use active pickups. Old pickups thus «are thrown out». Active pickups and electronics from EMG are popular (interesting article about these pickups and application of active electronics The active pickups: theory and practice, Russian). Besides there is a lot of successful examples of use of active electronics such «grandees» as Eric Clapton, Larry Carlton, Mick Rogers, all of «Metallica», Zakk Wylde, etc. I think, that competent use of active electronics can give good effect. As the guitarist seldom should play studios in «ideal» conditions. And if it is necessary to act frequently in various places - it happens so, that there is not enough time that it is good to tune up the equipment, active electronics at the simplicity can expand essentially opportunities of a «guitar - amplifier» tandem. In this article I have tried to describe results of the long enough experiments with active electronics for a guitar. That it has turned out - to your justice! :)
IDEAAfter I have created the project AGA (Built-In Guitar Preamp "AGA" (Alt's Guitar Amp), Russian) very few people has tried it to repeat. It is clear, the thing has turned out complex enough (especially - there is no PCB), and absolutely non-standard - actually this is stompbox built in a guitar. There was an idea - to make something easier as well as for reproduction and for wider application to be interesting to the greater community. As during creation of AGA - there were some not finished ideas. I have tried to create active electronics for guitars with standard pickups, minimally making changes in a sound, but some additional useful modes are entered. I think, the guitarist often needs only several good sounds, others are used rather seldom. Also I have tried «to extend» pickup features, having applied completely new «know-how». And here that has turned out. I named it SAGE ;) Certainly, preamp is made with FETs as I think that is the most «guitar» semiconductors :).
Small departureFirst of all - no active electronics will rescue, if your guitar will not be correctly shielded and grounded. How to make it -- it is wonderfully described in article (Quieting the Beast, Shielding a Strat, English) - in general a remarkable site, I recommend it very much for those who want to improve original sounding of the guitar by the minimal expenses. Especially, if you have «singles» – it have to make such modernization. Only if you were going to make active electronics - do not make a part of the standard guitar wiring after switches. To be exact - just connect pickups to the switch, and start to make SAGE further :). Though, it is quite probable, that after you modify your guitar - you do not want to make any active electronics any more - the sound will arrange you completely! Don’t worry, I shall not take offence – it’s great that your guitar began to sound better such simple way! :)
And still, we shall consider that you already modified a guitar, but want much more. What you expect for?
OPPORTUNITIES1. 3 modes of amplifying (microswitch S1) - «Pristine» -- a pure signal, linear amplification (some hi-ends) - «Bulgy» -- rise of mids, light distortions - «Dense» -- a loud dense signal with already a little noticeable distortions 2. Knob «Alter» - Adjustment of resonant frequency of the pickup. A mode of the «virtual pickup». 3. Knob «Gain» - Adjustment of an output level, amplification. 4. A small draw current, less then 1mA.
THE SCHEMATICSThe schematic of the preamp is represented on pic.1
Pic.1. SAGE – base schematic
At first sight it is yet another clone of so-called «Till schematic» (see A Discrete FET Guitar Preamp, English), by the way, it is completely standard schematic of the amplifier on FET which can be found in any textbook on electronics. However there are some interesting modifications and completely new «know-how» in SAGE :) The main amplifying cascade is made with J1 - it is known 2SK170BL. I think – it is the best field effect transistor for preliminary cascades. By the way, don’t worry, if you have not any and may be it is not expected - another variant of the schematic with popular J201 has specially been made also :) The gain of the cascade has been chosen in limits 10-12dB (3-4 times). Thus the signal on an output from the majority of guitar pickups will not overload an input. And there are no appreciable limitations on an output. Unless at very strong stroke of strings there will be cut tops of peaks. But such distortions (at the moment of strong attack) usually are not noticeable, as «sharpness» of attack masks these cuttings. Distortions not appear at all when you’re playing singles.
DIFFERENCES AND THEIR DESCRIPTION1. As the transistor 2SK170BL has very small cut-off voltage (usually 0.4-0.5V, rare 0.6V) is can lead to that the guitar signal will be limited «on an input», any gain of the cascade we would do. And in fact – we need the linear amplifier! Therefore the gate biasing is a little changed. Resistor R4 is added. It helps also to arrange a lower gain of the cascade, thus, practically not changing DC conditions. Actually, due to the watching feedback of resistor R4 because of which the maximal amplitude undistorted “on input» a signal increases up to V(off)*(R4+R2)/R2 is formed, in this case it will be about 1.2V, that it is quite enough for almost all guitar signals. Amplification of the cascade on mid frequencies in a mode «Pristine» is approximately calculated under formula R3/(R2+R4+Rs), where Rs - the minimal «source-drain» resistance of FET. In this case they can be neglected.
2. Small rise of high frequencies is made for brighter guitar sounding. It is made with the help of capacitor C9. If this rise is not necessary - it is possible C9 to exclude simply. Capacitor C3 cuts off the highest frequencies also reduces high-frequency noise and buzz. It is noticeable in modes with high gain when the signal on an output of the cascade starts to be limited. At desire - it is possible to exclude.
3. Very useful mode «Bulgy», when gain of the cascade grows approximately up to 20-30dB on frequency 1kHz (10-30 times) with raise of mid and high (guitar high) frequencies. Similar effects frequently uses many guitarists as well as with special stompboxes (for ex. "Brian May Treble Booster" and variations English) and with simply adjusting the stompbox to rise up mids and highs, as it did Steve Ray Vaughan with his «Tube Screamer» (see article about «pure» buster where it is in detail written about rise of mids and highs Do we need another "Clean Boost"? (Russian) In this mode the signal will be overdriven already, though the sound will be close to «Clean» channel of the tube amplifier with light drive. Playing with singles (or humbuckers in a split mode) distortions practically are not appreciable - the sound is clean enough but colored and tight. As a whole the sound is a little bit similar to a standard sound for «Crunch» channel of amp with light drive. In previous preamp AGA this mode has been realized in another way, as it would be desirable to come nearer to «Treble Booster» schematic. However, this mode in SAGE is made differently. This mode is provided with connection of C5-R5 chain with the right positions of switch S1. Capacitor C5 is not so big that leads to rise only mid and high frequencies. This circuit solution provides less noise than «classical» «Treble Booster», though frequency response differs a little bit than original. But on hearing it sounds practically the same. It is necessary to note, that in classical « Treble Booster « the small resonance on frequency about 1kHz (the central frequency depends basically on inductance of the pickup) is formed. Exactly the same resonance is not present in SAGE, but with knob «Alter» it is possible to change position of this resonance in wider range (see further details) Gain of the cascade on mid frequencies in this mode is approximately calculated under formula R3/(R5+Rs), where Rs - the minimal «source-drain» resistance of FET. In this case Rs is already comparable with R5. The gain in this mode can be arranged with resistor R5 (at 500 Ohm - gain is about 20dB)
4. The mode «Dense» turns out in the left position of the switch S1. Capacitor C4 is connected here. Therefore the maximal rise is about 30-36dB (30-60 times) on mids but lower frequencies also rise up. This mode makes already noticeably distortions of a signal. It has to use to «warm-up» the amplifier (better tube). The sound thus will be rather «fat» and «dense». It is inexpedient to use this mode without the subsequent overdrive or distortion, though you’ll decide! For example I try to overload the Boss VF-1 (the digital processor of wide application) – sounds great! The gain of the cascade on average frequencies in this mode is approximately calculated under formula R3/Rs, where Rs - the minimal «source-drain» resistance of FET. If you want to lower gain of the cascade in this mode - it can be made with consecutive resistor with C5 from 100 up to 200 Ohm.
ATTENTION! A signal swing at modes «Bulgy» and «Dense» is up to 8 volt (double amplitude) on output! Use these modes accurately to prevent burn of input circuits of the subsequent stompbox or the amplifier. Though if you play with the tube amplifier - it should sound very fine! In general – you can experiment with but be careful. For this purpose you have knob «Gain».
THE KNOW-HOWAlso there is a cascade on J2! And what it is? That is the main «know-how»! Though it is quite possible, that something similar has been thought up already for a long time (may be not for a guitar electronics but for something else). But I have looked over lot of various schematics and nothing of such kind have found out.
May be you already know, there is a peak at frequency response (FR) of the guitar pickup caused by inductance and capacitance of the pickup and also other capacitances including parasitic capacitance (for example - capacitance of a guitar cable). It is possible to read in detail about it in article "The Secrets of Electric Guitar Pickups" (English). Look at the pictures and the table with Resonant frequencies of some well-know pickups (English) - and all becomes clear to you. The long or the bad cable can affect essentially on «brightness» of a sound (it occurs because of the bigger parasitic capacitance of a cable). By the way, the Russian variant of this article with additional interesting researches can see on "Pickups and they basic features" (Russian). Sense that position and height of this peak - a resonance - in many respects define character of sounding of the pickup: his «sonority», «smoothness», «brightness», «bell-like sounding», etc. Changing height and position of a peak it is possible to change considerably a sound, «to change» the pickup. Though, certainly, you can’t made «Seymour Dunkan» from the fake pickup in such a way, but it is the way to improve and vary a sound of pickups! And also it is necessary to note, that you cannot made single from humbucker, that just is very well shown in the last part of article "Pickups and they basic features" (Russian), and also confirmed with me «on hearing». So if you are interested with sounding of humbucker as single - the best way is to make split of one coil of pickup. How to make it - also look in "Humbucker Switching", (English)
An idea of changing the central frequency of peak - a resonance of the guitar pickup - did not give a rest to me for a long time. Some guitarists, for example, use the special rotary switch with the different capacitors connected in parallel to the pickup. I read, so did B.B.King with his guitar (may be Albert King? I do not remember precisely, sorry). Though I did not see the schematics. But I think the rotary switch is not so convenient and it is somehow ugly. It is possible to make usual variable 2-nd order Sallen-Key filter as Vladimir Kolpakov has made, for example, in his circuit of active electronics "The active pickups: theory and practice" (Russian). I did almost the same in the built-in AGA (Alt's Guitar Amp), see the last cascade. But it somehow is «not absolutely fair», since native property (inductance) of the pickup is not used.
Very interesting idea of varying of resonance frequency is used in the schematic of usual “Wah-Wah”. See article "The Technology of Wah Pedals" (English) to discover. The special inductor (about 0.5-0.8Hn) is used in the «Wah», and the capacitance changes by means of the pot and resonance frequency has been varied also. It occurs because of changing of the feedback factor by the «Wah» pot. I tried to do so in similar manner, but it turned out somehow «not so good» on hearing, and frequency varied only in 1.5-2 times (usually from 1.2kHz up to 2.0-2.2 kHz for humbucker pickup), and changing modes of the amplifier («Bulge», «Dense») results turned out unpredictable. The idea has come as always unexpectedly. Idea of a «usual» guitar tone regulator guitar has been taken. By the way, let's talk a little about it.
Standard Guitar ElectronicsLet's look, what occurs when you turn knobs in a standard guitar. Here the schematic of a standard guitar. For simplicity switches of pickups and various modifications are not shown. At simple -- «Pickup», «Tone» and «Volume». And also I have still represented a cable since his capacitance essentially influences on FR, and also the input circuit of the guitar amplifier (or stompbox).
Pic.2. Standard guitar schematic connected to amp (simplified)
The tone in a guitar is adjusted effectively enough, but in average positions of a pot the guitar sounds «soft» and «pale», it occurs because of absence of peak in average positions of the pickup. See pic.3
Pic.3. Dependence of guitar frequency response on «Tone» pot.
But the idea is very simple - the capacitor is connected in parallel with the pickup, and his influence is adjusted by potentiometer P2. Poorly that in average positions the potentiometer also influences on height of a resonance, and peak is not present. But also the regulator of loudness P1 «Volume» influences the peak, especially when we start to change volume! It is visible on pic.4
Pic.4. Influence of guitar «Volume» pot on the resonance behavior
Nothing’s good. The resonance very quickly disappears at reduction of volume. By the way this situation will be not improved even neither with the voltage follower, nor with Till schematic put on an output of a guitar. It is possible to put, certainly, additional capacitor Cc and resistor Rc between a cursor and the top conclusion under schematic P1 as it is recommended on www.guitarnuts.com/wiring/volpass.php (English), thus the situation will a little improve (it is shown on fig. 5), but nevertheless it too «not that wee need».
Pic.5. Influence of guitar «Volume» pot with additional Rc-Cc chain on the resonance behavior
Realization of ideaBut how we can lower influence P2 on height of a resonance and at the same time effectively adjust a tone? It appeared to be possible to make it simply! :). The usual voltage follower on FET (to exclude influence of the high impedance of the pickup), and then potentiometer P2 with small resistance (10kOhm) which adjusts «influence» of the capacitor. Actually this potentiometer raises potential of the capacitor to potential of a signal, thus «reducing» it effective capacitance. And as value of P2 is small - it does not influence reduction of peak height. For clarity - let’s see an example. Assuming we have put a slider of pot P2 on 1/5 part from the top of the schematic. Then the signal on a slider will be ~4/5 of input (we consider that gain of VF on J2 is 1.0X or 0dB). Then the voltage on C8 will be 1/5 of a signal. And it means that the effective capacitance will decrease to 1/5 of C8! Thus it turns out, that the maximal effective capacitance is capacitance of C7 when slider P2 is in the bottom position of the schematic (actually - shorted to the ground), and the minimal capacitance is defined by transfer factor of the VF on J2, is more exact under formula C8*(1-G(J2)). And of course, it is necessary to take into account capacitance of C7 (connected in serial with C8 and reduces the common capacitance) and other effects. But in practice, it is possible to change thus effective capacitance C8 in 20-30 times, and accordingly, frequency in 4-5 times - and it is quite enough! ;) The schematic has turned out very simple and beautiful! Look at diagram on pic.6. Different modes of SAGE and also changes of resistance of the top part of P2 in a range from 100 Ohm up to 25kOhm with step in 2 times are shown. It means that in this schematic we need to use «Audio» (with logarithmic dependence) pots. Why 25k? See further details.
Pic.6. SAGE – Frequency response in different modes. Dependence of the resonance shift on «Alter» pot.
Diagrams are all calculated. Measurements of real FR for such schematic are rather difficult as there is an influence of inductance of the pickup (what we fight for!). Measurements of a signal without connection of the pickup will not show no peak. However all is very well appreciable on hearing! :) By the way, rotation of a pot «Alter» reminds sound of «Wah-Wah» a little, but in extreme position the sound is more similar not to «AH», but to «EH» (but not to «weeeeh»!). It’s even better n this case –. That is so it turns out – «Weh-Weh» in a guitar! Thus the regulator «Gain» does not influence at all on FR! Only reduces a target level! Pay also attention that in modes «Bulgy» and «Dense» the range of adjustment of a resonance is less, than in a mode «Pristine». It occurs that at the transistor 2SK170BL has high enough input capacitance about 30pF. However, it does not bad in playing, as modes with high amplification usually is necessary «to roll off» just high frequencies for the greater clearness and recognition of guitar sound. By the way, in other variants SAGE (are considered below) such effect is not present, so – you’ll choose what it is better! It is need to do the VF on FET that there were small noise, and high entrance resistance. Then the height of peak will be high enough and the sound «is brighter», and differently - what we fight for? ;) There are minuses of course. First of all is that it is necessary to put a potentiometer of small value, a maximum 20-30kOhms. But it is really need - in fact we fight with noise and for high peak so it need to use pots of small values since thermal noise is always proportional to a square root from size of resistance. It founded that EMG has «Guitar» pots of 25kOhms. As it is already significant more than 10kOhms – it better to shunt such pot with resistors. See pic.7a. By the way, diagrams on pic.6 are shown for such schematic. The «Gain» pot - it is possible to put almost anyone «guitar» pot, for example – 220kOhms. However thus also it is better to shunt it with resistor 68kOhms (it may be less, down to 33kOhms). It also is shown on pic.7a. It need to reduce target resistance and, accordingly, to lower influence of capacitance of a cable you connect to your favorite stompbox, or to the amplifier. By the way, it can be that you’ll exclude from a sound path other stompboxes and play directly in the amplifier. There are enough opportunities for a various sound! :)
Pic.7 a) Usage of 25k pot for «Alter» b) Usage of 250k pot for «Gain»
So, in result the very simple schematic that carries out many functions has turned out. The draw current of the schematic - is less then 1mA. It will enable you to play till 600 hours (with good alkaline battery). Of course, it is possible to make a draw smaller but then noise would increase. It was decided the current draw up to 1mA is a small enough. For comparison the AGA consumes about 2.5mA, the battery did not change in half-year, though I’m not the inveterate guitarist :)
VARIANTS OF SCHEMATICS It was decided to design variants of this schematic that it was possible to repeat more easily on different details.
A variant 1 Popular transistors. Pic.8
Pic.8 SAGE -- Variant with popular FETs
The amplifying cascade is made on J201. Better if you check out cut-off voltage of J201 you use. It will be 0.5-1.0V. It is possible to use other popular FETs such as J202 and 2N5457, 2N5458, 2N5459, better if you select FETs with high admittance at small drain current (about 1mA). Unfortunately, I have neither J201 nor 2N5458 nor others; therefore I did not try them. But I have Russian FETs KP303 that parameters are very similar with J201. The cascade of the VF for adjustment of a resonance is composite. It is recommended by Viktor Kempf, see article "Application of FETs in Distortion Devices" (Russian) about unique «4FET» technology. By the way he has already had time to test SAGE with KP303 (J201 analog) - all works fine! ;). Modes «Bulgy» and «Dense» will have not such big gain in this variant, because of not so big admittance of J201. Overloads will be smaller and little bit softer. Resistor R5 thus can be excluded absolutely. Noise also will be higher in this variant, but a little. It is quite probable, this variant on a hearing will be pleasant to someone even more. A current draw of this schematic is about 0.7mA, because of use of FETs with less admittance. If you want to simplify this circuit, but diminish a little the range of adjustment – you can take off FET J3, and put instead of him the resistor of 10-15kOhm. The better characteristics will be, if thus instead of J2 will stand BS170 (MOSFET), but noise thus will be higher. Variants of such voltage followers are shown on Pic.9
Pic.9 a) VF with one J201 b) VF with MOSFET - BS170
A variant 2 The similar schematic on op-amp is represented on pic.10
Pic.10 SAGE -- Variant with op-amps
The schematic with op-amp has been designed to check up noise at first. And also that the VF with op-amp turns out more exact (Ku absolutely insignificantly differs from 1.0), accordingly - adjustment of a resonance is wider. Besides the schematic on op-amp practically does not need to be tuned. It is very simple to make up. The amplifier is made on A1, voltage follower - A2. I have taken TL082 as I have not others op-amp with FET input. Resistor R11 is put for restriction of adjustment of the maximal frequency of a resonance up to 4.5kHz. You can decrease it or to take it off, but it also will lead to higher noise level in top position of slider P2 under the schematic. Of course, there are few lacks in this schematic. First of all - the big current draw (hardly it is more 2mA), a smaller dynamic range (swell is up to 6 volt on an output), and the bigger noise. But it is easier for reproduce. It is interesting to make such schematic with better OP-AMP, for example TLC2262 (it is less noise, current draw, Rail-To-Rail output, softer overload etc.) that are applied in the known schematic «SansAmp GT-2». Also it is possible to try the some popular op-amp from «Analog Devices«. But I have not any now, unfortunately.
Other variants You can «mix up» cascades completely free. You can, for example, make the amplifying cascade with op-amp, and make a regulator «Alter» with 2SK170BL. By the way it is very good variant as it is simple in tune (practically it is not required) and it has low level of noise. Other «mixes» are possible also. All set of above variants have been made on a model board and then «reshuffled» among themselves (there have been checked up all about 10 variants), the sound of all is very close, changes are insignificant! :). Though, it is necessary to note, that restriction of a signal with op-amp more hard, and so - more noticeable, and also there is no «warm». Though it taste to you!
And one more thing. The power on switch is not specified on the schematic. A power connects by «ground» sleeve of a cable jack when you put it to guitar. So if you do not want the battery prematurely failed - simply pull out jack from a guitar. Of course, the guitar jack should have 3 contacts.
NOISE So, what we fight for? We need hard to low-noise schematic! Schematics have been designed so that noise is a little. Basically it depends on active elements (FET and OA), and also on values of resistance that are connected with a signal in serial. They are R2, R4, R5 and pot P2. All of them are smaller or comparable to active resistance of the pickups. But pickup impedance on high frequencies is much higher. Therefore noises practically did not added. There was an attempt to compare the schematic among them for noise. For this purpose noise of different SAGE variants has been recorded on a computer (sound card M-Audio Audiophile 2496), and then analyzed. But complexity is that rather difficult to make identical gain for the different variants. Therefore the received results cannot be named completely authentic. However there are some supervision and recommendations: 1. The noisiest cascade is the cascade of adjustment of a resonance on J2 (or A2). If there costs op-amp or MOSFET - the schematic will rustle more, but is insignificant. 2. Do not put MOSFET such as BS170 in the amplifying cascade instead of J1! It has remarkable characteristics of amplification but rather bad on noise. 3. The op-amp schematic rustles not strongly, practically does not differ from the schematic on FET. It is caused by that we hear the most significant noise in a range 2-5kHz where the resonance of the pickup gives the greater noise, than op-amp noise (noise of the pickup reaches up to 100nV/VHz on frequency 2.5-4kHz!). However the best way is to make «Alter» cascade (J2) with FET 2SK170BL for smaller noise. 4. It is possible to lower size of a resonance if it seems, that the guitar «rings» (there is such sensation when noise «rings» on high frequencies) – you can do it with reducing resistance of R1. But it is need not to reduce more than in 2 times.
TUNINGFirst of all you have to adjust voltages of cascades on a direct current. However 15 samples 2SK170BL (different FET were put in the same schematic) have been measured - voltages varied insignificantly. So may be you need not to adjust anything, but you better check up voltages on source J1 and drain J2 with elementary tester. Easiest way is to put instead of R3 the trim pot of 10kOhm. But it is better to pick up value of R2. Voltages (for basic schematic) Vd (J1) ~ 4.5-5.2V, tuned with R3 Vs (J2) ~ 2.5-6.0V, tuned with R7
Voltages (for popular FETs schematic) Vd (J1) ~ 5.0-6.0V, tuned with R3 Vs (J2) ~ 4.5-7.0V, autotuned ;)
In the op-amp schematic the most important is to check up a battery and the voltage on bias point V1/2 = 4.5V
After that all will works fine!
THE PRINTED-CIRCUIT-BOARD AND INSTALLATIONThe Lord good! Well not spets I on distributing and etching of payments! I usually put everything on perfboard and connect elements with wires. Schematics are simple, you can make it in a way that frequently do on www.runoffgroove.com, (for example runoffgroove.com "Odie"). If someone will make PCB for this project – it will be great!
CUSTOMIZATONThat it is possible to change for the taste. 1. To change the gain of the cascade in a mode «Pristine» - try resistor R4. Be not fond, it not «loudness»! Changes insignificant, simply to pick up to clean up possible distortions. If you raise it strongly -- the minimal voltage on output J1 will decrease, and the dynamic range will be narrowed. Also you can to take off or change small rise of highs («brightness») with capacitor C9 2. To change the gain of the cascade in a mode «Bulgy» - try resistor R5. It can be in wider range. But it is not necessary to be fond too. 3. If you want to reduce the gain in a mode «Dense» - enter the serial resistor with capacitor C4. In a variant with op-amp - increase R2. 4. Capacities C4 and C5 influence quantity of low frequencies in a mode «Dense» and «Bulgy» accordingly. If you increase them – you get more lows. If you reduce them - on the contrary. 5. If you would like to decrease all range of adjustment «Alter» to lower frequencies – you can replace capacitor C8 to 6.8kOhm. If on the contrary - to 3.3kOhm. Don’t you try another values better, but how could I keep you off? ;) 6. Probably you would not like to put the additional switch on a guitar (to not drill additional hole on the varnished guitar panel). Then I advise you choose to yourself one of modes «Bulgy» or «Dense» (since I think, that is very convenient to use them when you playing guitar) and buy a pot with the «push-pull» switch.
SAMPLESSamples have not been recorded, since all sounds very strongly depend on devices SAGE plug to. I have tube amp only in our practice base, but there is no recorded device. But even with my home solid-state inexpensive «Yerasov GA-15R» (little home practice amp with built-in «SansAmp-like» scheme) all sounds great! More various and interesting! I think it is quite possible that some samples will be recorded in the near future :) I can notice, though SAGE less versatile than AGA, but I am going to give AGA to somebody, and to build SAGE in. Only one reason holds me from it - I search to myself for the 25k pot from EMG. As I find - at once I put SAGE in immediately.
RECOMMENDATIONS TO APPLICATIONThe most interesting! What for all was so is smartly made? ;) - When you play some light rhythm or blues – try to use unequivocally a mode «Pristine», may be slightly to twist «Alter» from edge position to add to a sound some response - You need the sound for blues solo? Turn on «Bulgy» and reduce «Gain». You can twist «Alter» to bring some «flexibility». - You want «heavy-metal»? Then switch on «Bulgy» and loud out «Gain» to the maximum! You hear something hisses and want more rage? Twist away «Alter» completely – that’s IT! Here they are screams and punches! You need more «meat»? Then switch on «Dense»! - And can be you love a Santana-like sound? Well then you should turn-on «Bulge», decrease «Gain» slightly, and to get «Alter» almost to the minimum.. Very sensitive mode, here they are «guts and veins»!
In general - all in your hands and behind your hands. Both pots and switch - rather strongly influences a sound! Of course - the sound in many manners depends on amplifier you play! SAGE - is made to expand opportunities of a «guitar - amplifier« chain, and even more it is possible that in some cases you exclude intermediate stompbox! But the amplifier, the guitar amplifier - should be plugged in! :)
And at last - when will make SAGE and try to check it with the guitar - it is very desirable to check it having disconnected «native» guitar tone and volume. Also better without a guitar cable but simply having connected the output from switches with short wires directly to PCB or MB. Then you’ll have got the effect. BUT! You can use SAGE as stompbox. Though, of course, the «Alter» will effect absolutely in another way.. ;) But it is quite possible, that 3-modes with the linear amplifier and high gain buster will be enough for you!
CONTACTSYou can write all questions and wishes at the following forums (Russian) where I appear on a regular basis appear with nick alt www.gtlab.net/forum/index.php?showforum=2 Sometimes I come to popular forum (English) diystompboxes.com/sboxforum/index.php And I will try to help you and answer your questions. I shall be grateful for constructive remarks and also for offers. It is very interesting to me, as all this will sound at you :)
WISH YOU SUCCESSES IN GUITAR AMPLIFICATION! ;)
REGARDSMany thanks to Victor Kempf (xbananov) for discussion and useful advice at writing up of article. Also thanks to Dmitriy Plakhin (DDD) for big help with English variant of this article. Also thanks for all participants of forums www.gtlab.net/forum/index.php?showforum=2 For that you are and constantly excite on creation of something new :)
Special thanks for all authors whose sites and pages I used in this article. Your information has helped me in many ways!
With the best regards, Alexander Troshnev (alt) Russia, Siberia, Novosibirsk
©2005 Alexander Troshnev
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