| malky |
Hello. I don't have a guitar amp, so I connect it to my onboard sound card... :(. Anyway, until I have the sufficient funds to purchase a real amp, I would like to build something. What I need is the simplest, 20-25w guitar amp w/out volume control or such. I just want to plug my guitar in and hear the sound...
Anyone knows some circuit that meets that?
thank you,
malky |
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| fezz |
trust me - a 20w or more amp will need a volume control, even if you dont mind damaging your hearing, your neighbours might mind a bit.
use the stnadard gain clone (found throughout this forum) you can use a normal hi-fi amplfier to amplify a guitar
finding a speaker shouldn't be that hard, any 50 w speaker (you could use an old hi-fi speaker) will work because guitars use frequencys very easy for normal spreakers to produce. |
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| mikelm |
probably malky is intending to use the volume control on his guitar. should be fine so long as the guitar is plugged in before the amp is turned on. Otherwise the normal plugging in noise could be painful.
If you choose to build an inverting amp be sure to tie the i/p to ground with a 1/2 meg resistor ( or similar ) so if the amp is on with guitar unplugged the i/p is referenced to ground
mike |
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| Bricolo |
| quote: | Originally posted by mikelm
probably malky is intending to use the volume control on his guitar. should be fine so long as the guitar is plugged in before the amp is turned on. Otherwise the normal plugging in noise could be painful.
If you choose to build an inverting amp be sure to tie the i/p to ground with a 1/2 meg resistor ( or similar ) so if the amp is on with guitar unplugged the i/p is referenced to ground
mike |
this is one solution
using a volume pot is the other one
what impedance can a guitar drive? A gainclone has 10k Ohm input impedance, is this good for a guitar? |
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| planet10 |
| quote: | Originally posted by fezz
use the stnadard gain clone (found throughout this forum) you can use a normal hi-fi amplfier to amplify a guitar |
Don't guitar amps have to have tubes?
:scratch:
dave :) |
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| Bricolo |
| quote: | Originally posted by planet10
Don't guitar amps have to have tubes?
:scratch:
dave :) |
don't ALL amps have to have tubes? ;) |
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| moamps |
| quote: | Originally posted by malky
Hello. I don't have a guitar amp, so I connect it to my onboard sound card... :(. Anyway, until I have the sufficient funds to purchase a real amp, I would like to build something. What I need is the simplest, 20-25w guitar amp w/out volume control or such. I just want to plug my guitar in and hear the sound...
Anyone knows some circuit that meets that?
thank you,
malky |
Hi,
guitar pick-up need preamp with high input impedance.
Try this http://sound.westhost.com/project27b.htm
Regards |
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| mrfeedback |
I have setup two amplifier systems for my flat-mate.
The first is a Radio Shack 30W PA amplifier driving an 8" single way box.
The acoustic guitar plugs straight into a mic input, and this works fine.
Secondly, I have an old cassete deck in my main system.
The guitar plugs into the cassette deck mic input, and we get 200W of clean guitar sound when we want it.
You could use a portable radio-cassette player with mic input, or line input via a small preamp box.
Eric. |
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| malky |
Well, I guess I should be more specific. I have a speaker already, some 2-driver car speaker, and I was intending to use the volume control on my guitar and on my Multi-Effect (Zoom 606). I just need some simple schematic that will amplify the sound... it don't have to be a Tube amp, but rather a chip (like TDA2030 or such) amp because it's cheaper and simpler..
thanx |
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| usa_satriani |
to wait in better conditions u can get this :
Steinberg wavelab + plugin amplitube : great sounds with the PC ;) |
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| tipton |
I seen a post for cheap guitar amp's in the Traiding Post section. Good luck
Tipton. |
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| nobody special |
| quote: | Originally posted by malky
Well, I guess I should be more specific. I have a speaker already, some 2-driver car speaker, and I was intending to use the volume control on my guitar and on my Multi-Effect (Zoom 606). I just need some simple schematic that will amplify the sound... it don't have to be a Tube amp, but rather a chip (like TDA2030 or such) amp because it's cheaper and simpler..
thanx |
Gainclone... Gainclone... Gainclone...Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone... Gainclone...
I had to see how many more times it could be mentioned. There is a gainclone quota, you know.
Seriously though... it would be a decent cheap amp for what you want.
Steve |
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| IanHarvey |
| quote: | Originally posted by Bricolo
what impedance can a guitar drive? A gainclone has 10k Ohm input impedance, is this good for a guitar? |
Much less than 100K and the sound gets distinctly naff (you lose lots of high frequencies). You don't need much voltage gain, as you'll get 100mV to a volt or two depending on pickups and how hard you're playing.
Cjeers
IH |
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| nobody special |
| Since he is using his multi-effects processor as a preamp, the guitar impedance doesn't much matter. |
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| malky |
| This may sound shocking, but I don't know what it is.. |
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| li_gangyi |
Hey~~! Guitar Amps HAVE TO BE TUBE~! Or else you dun get the nice overdrive...maybe you dun play that way...whu noes...for a real simple Tube guitar amp project go here
www.ax84.com/index.html
hope this helps you...the transformers are not cheap though... |
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| newbie1 |
Why do guitar amps have to be tubes? There are plenty of guitar amps that are solid state. I agree that tube crunch sounds better than a FET crunch but some people like the sound of a solid state guitar amp. Anyway, I do have a question.
I don't know a lot about how you actually achive distortion in a guitar amplifier but I suspect it has something to do with overloading the feedback input. So if you were to use a gainclone layout just for pure amplification from the clipped signal of a preamp (distortion pedal), would a gainclone reproduce this signal just as good as a tube amp? Since are not actually clipping the opamp but just amplifying a signal that has already been clipped you wouldn't hear any nasty non-musical harmonics produced by a clipped opamp...or would you? |
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| GregGC |
| quote: | Originally posted by newbie1
Why do guitar amps have to be tubes? There are plenty of guitar amps that are solid state. I agree that tube crunch sounds better than a FET crunch but some people like the sound of a solid state guitar amp. Anyway, I do have a question.
I don't know a lot about how you actually achive distortion in a guitar amplifier but I suspect it has something to do with overloading the feedback input. So if you were to use a gainclone layout just for pure amplification from the clipped signal of a preamp (distortion pedal), would a gainclone reproduce this signal just as good as a tube amp? Since are not actually clipping the opamp but just amplifying a signal that has already been clipped you wouldn't hear any nasty non-musical harmonics produced by a clipped opamp...or would you? |
Just a thought: Chipamp with a tube preamp. The preamp can be brought to saturation/clipping which will give the tube characteristic and the chipamp will do the amplification. The best of both worlds. |
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| newbie1 |
| quote: | | Just a thought: Chipamp with a tube preamp. The preamp can be brought to saturation/clipping which will give the tube characteristic and the chipamp will do the amplification. The best of both worlds. |
My thoughts exactly. I think you could probably even acheive a good sound with solid-state preamp...just don't want to clip an opamp. Almost all distortion pedals and floor boards use solid-state components...If I'm not mistaken. |
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| matjans |
| don't you need a mic preamp before hooking it up to a chip amp? Just a thought... |
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| newbie1 |
| quote: | Originally posted by matjans
don't you need a mic preamp before hooking it up to a chip amp? Just a thought... |
Hmm..what for? You should already have about a 2V input signal from the pedal or floor board. However, you may need a resistor to drop the voltage as I think the max input for voltage for the LM3875 was around 850mV@40W ouput according to the spec sheet. |
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| GregGC |
| I think it can be a very nice guitar amp if you have all the other distortion pedals and stuff that I don't know about. Put the input cap though and the Feedback cap also (same as the data sheet sch.). The quality you need is not what you'd want for the hi end hifi. |
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| leadbelly |
| quote: | Originally posted by GregGC
Just a thought: Chipamp with a tube preamp. The preamp can be brought to saturation/clipping which will give the tube characteristic and the chipamp will do the amplification. The best of both worlds. |
You will get a dirty sound this way, but not nearly as brown as you're thinking. The signature distortion sound of blues, rock, and so on is from overdriven tube power stages and cone breakup of the speaker. An overdriven tube preamp stage will not be nearly as meaty. |
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| sobazz |
Regarding the combination of tubes and fets - my good ol' Roland Bolt-60 has a fet preamp and tube output stage. There's no doubt, that the overdrive is not as good as Fender's or Mesa's, but the clean is smashing!
A good overdrive will most surely require a tube stage too, or?
Btw - the Bolt uses two 6L6GC and an ECC81 (or 83 - don't remember). What is the ECC* tube for? |
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| GregGC |
| quote: | Originally posted by leadbelly
You will get a dirty sound this way, but not nearly as brown as you're thinking. The signature distortion sound of blues, rock, and so on is from overdriven tube power stages and cone breakup of the speaker. An overdriven tube preamp stage will not be nearly as meaty. |
You guys ar the Pro's there. Mine was just a guess. |
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| skyraider |
you definitely need a preamp, even though ure using multi-effects to boost the pickup signal. One main reason is these: you cannot control the tones(bass, mid and treble) with the multi-effects, so you might not like the sound you get. And, having a preamp makes it easier to turn the music up and down. I built a simple 15W amp using TDA2030A, and a preamp copied from this website http://sound.westhost.com/project27b.htm
I modified certain values in the tone controls to imitate the fender sound. At high gains, this amp clips just as nice as tubes. The secret here is to use different clipping diodes, to get non-symetrical clipping. sweet and smooth. If you dont want the distortion, just take out the clipping diodes, and you get a cleaner sound. Read the instructions from the website for more details. |
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| leadbelly |
| quote: | Originally posted by GregGC
You guys ar the Pro's there. Mine was just a guess. |
I wasn't trying to knock you down, just point out the pitfalls. I'm interested in the same thing:
http://www.diyaudio.com/forums/show...&threadid=22858
But I gave up on my research when I couldn't find a good existing design as a starting point. :) |
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| GregGC |
| quote: | Originally posted by leadbelly
I wasn't trying to knock you down, just point out the pitfalls. I'm interested in the same thing:
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Thanks, though I didn't take it that way. All is fine. Always up to a good discussion.
I really don't have experience with tube amps and I can't comment on how they sound compare to the SS as guitar amps.
I know that if I have a good poweramp and a good signal shaping preamp can't be bad. I know GC is a very good poweramp (I listen to one at home all the time).
/Greg |
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| ir |
tube pre/transistor power is probably the best way to go
the tube adds warmth and bluesy goodness while the SS power stage adds volume - prcise volume. it simply takes the output from the pre and makes it louder wihtout adding anything of it's own
yeah an all tube amps sounds nicer. tube/SS combo is best.
a mate of mine has a Fender Rockpro 1200. it's a 100W Transistor power amp fed by a tube preamp. and this things got balls
anywasy back to the topic
a gainclone guitar am pwill do fine - better then fine even. my fender 112 is all transistor and sounds beaut. it's clean and clear, loud, and crunchy as hell if need be.
internnaly it's all ultra low noise op amps for the pre and two Power Amp IC's - i can't remember what they are i thnk maybe TDA something?
anyway it's a farily easy design - and way more then you need.
i too was thinking of building a guitar amp based on an LM series chip. i was looking at just an LM1785 consutructed exactly as per datasheet and a dual op-amp preamp/distortion stage - ie 1 brings up the signal, the other adds distortion (switchable)
there's really nothing to it |
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| leadbelly |
| quote: | Originally posted by ir
i too was thinking of building a guitar amp based on an LM series chip. i was looking at just an LM1785 consutructed exactly as per datasheet and a dual op-amp preamp/distortion stage - ie 1 brings up the signal, the other adds distortion (switchable)
there's really nothing to it |
It has been posted many times by the gainclone gurus that this will not work very well. When an LM chip is overdriven, I am told that you do not get the typical sound of a transistor clipping, which you are probably assuming, but a cacophony from whatever SPiKE does. But hey, it won't cost you much to try it. |
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| ir |
you miss my point
the power amp stage (ie LM1875, 3886 whatever) is ONLY for amplification
the distortion is done in the preamp. 741 opamp distortion is quite good for a guitar (as the opamp is so rubbish). the LM1875 will just be adding volume to an already distoted signal
anyways no point arguing - i did it myself not more then 2 hours ago
plugged my guitar/fx unit into one channel of my LM1876 based amp (yeah it's a stero chip, who cares - they're all the same)
even without a preamp the sound is awesomely clear. and noiseless i should add. then when you kick in the fx pedal distortion the amp does a beautiful job of pulling the volume up without adding anything of it's own.
thats the difference with valve amps. in a valve guitar amp you DO overdirve the power amp. and the power Valves add their own flavour to the mix (a nice warm flavour - like coffee. i like coffee)
it's perfect in my view. altho if you were to build one from scratch you will proably want to add a simple preamp with tone control and slight gain. the output from a guitar isn't huge (mines not bad - dual humbuckers) To drive a 20W amp at 20W will require a little bit of gain in the pre stage. this is easily achieved with a single op-amp (preferably low-noise. OnSemi have some nice ones)
good luck |
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| newbie1 |
| quote: | Originally posted by ir
you miss my point
the power amp stage (ie LM1875, 3886 whatever) is ONLY for amplification
the distortion is done in the preamp. 741 opamp distortion is quite good for a guitar (as the opamp is so rubbish). the LM1875 will just be adding volume to an already distoted signal
anyways no point arguing - i did it myself not more then 2 hours ago
plugged my guitar/fx unit into one channel of my LM1876 based amp (yeah it's a stero chip, who cares - they're all the same)
even without a preamp the sound is awesomely clear. and noiseless i should add. then when you kick in the fx pedal distortion the amp does a beautiful job of pulling the volume up without adding anything of it's own.
thats the difference with valve amps. in a valve guitar amp you DO overdirve the power amp. and the power Valves add their own flavour to the mix (a nice warm flavour - like coffee. i like coffee)
it's perfect in my view. altho if you were to build one from scratch you will proably want to add a simple preamp with tone control and slight gain. the output from a guitar isn't huge (mines not bad - dual humbuckers) To drive a 20W amp at 20W will require a little bit of gain in the pre stage. this is easily achieved with a single op-amp (preferably low-noise. OnSemi have some nice ones)
good luck |
Wow! This is just as I suspected...but don't possess the the technical skills you do to construct the circuit. Very cool...I want to build one as soon as I can get my LM3875 to make some sound.
:bawling:
So you ave any pics of the amp? I would love to see some...especially how you wired the preamp for optimum distortion...got a schematic?
Quick questions. I have no idea what I am doing wrong here. I have wired up my LM3875 to the best of my knowledge according to the schematic but I get no output.
1) I am using a 13.8V DC supply, this should be sufficent for some output to occur...correct? I think this will give a total rail voltage of 27.3V, which is within the required voltage specs for the LM3875 (|V+| + |V-| = 20V to 84V). Anything wrong with this?
2) I am using RCA outputs with an adapter to a Discman for the signal source. I have attached aligator clips to the tips of the RCA's and connected the positive output to pin 7 with a 1K ohm resistor in series and the nagative RCA lead to ground. The schematic doesn't show where the negative signal source should be connected so I just assumed ground...am I way off base here?
3) My feedback circuit consists of a connection off pin 3 which connects to a 20K ohm resistor (in series) connected to 1K ohm resister which is connected to a 47 uF capacitor to ground. I have a connection from where the 20k ohm resistor meets the 1k ohm resistor and that connects to pin 8.
4) I don't have any caps on V+ or V- since the power souce is a bench power supply and registers to AC signal. Do I still need caps on V+ and V- if no AC signal is present?
5) Pin 3 goes to the positive terminal on a 6 ohm speaker and the negative terminal is connected to ground.
All grounds are at the same point on the circuit.
Anyhow...I can't get any sound of this chip and I have yet to make a working circuit so I don't know what's wrong. Kinda frustrated right now, gonna take a break. Anyone have any suggestions?
Thanks. |
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| skyraider |
| post the photo if you can |
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| skyraider |
in the preamp stage, you dont drive or distort the opamp to get distortion. actually you add clipping diodes to compress/clip the signal, to simulate the way tubes does when it is overdriven.
the main point of adding a preamp is to adjust the tones from your guitar, especially adding treble boost because the raw sound from your pickups are muddy. If you want to use Fxs as your preamp, it doesnt sound as nice as you get with a preamp. you might not need to overdrive your preamp because your Fxs can provide the distortion that you need, and also i believe your fxs can distort the sound better than any simple preamp that you build. I agree you should look into a single opamp preamp, with at least treble & bass boost, and volume. nevermind the distortion first. |
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| leadbelly |
| quote: | Originally posted by skyraider
in the preamp stage, you dont drive or distort the opamp to get distortion. actually you add clipping diodes to compress/clip the signal, to simulate the way tubes does when it is overdriven.
the main point of adding a preamp is to adjust the tones from your guitar, especially adding treble boost because the raw sound from your pickups are muddy. If you want to use Fxs as your preamp, it doesnt sound as nice as you get with a preamp. you might not need to overdrive your preamp because your Fxs can provide the distortion that you need, and also i believe your fxs can distort the sound better than any simple preamp that you build. I agree you should look into a single opamp preamp, with at least treble & bass boost, and volume. nevermind the distortion first. |
I counld not disagree more. If an amp cannot get a dirty tone on its own without an outboard effect, then it is not an electric guitar amp in my view. It is a PA amp. |
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| skyraider |
actually some people do prefer clean sound only from their amp;)
theres a lot of jazz players around
what i meant here is that you cannot get a sweet distortion with a SIMPLE preamp circuit. a good solid state which imitates tube distortion is hard to build. my idea is that let the Fxs alone does the distortion for him, and let his amp be a simple amp as he intended. Ive built a few 'simple' distortion circuits and frankly, they sucks. |
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| leadbelly |
| quote: | Originally posted by skyraider
actually some people do prefer clean sound only from their amp;)
theres a lot of jazz players around |
I agree, but commercial jazz combo amps can still get a bit of a dirty sound. :)
| quote: | Originally posted by skyraider
what i meant here is that you cannot get a sweet distortion with a SIMPLE preamp circuit. a good solid state which imitates tube distortion is hard to build. my idea is that let the Fxs alone does the distortion for him, and let his amp be a simple amp as he intended. Ive built a few 'simple' distortion circuits and frankly, they sucks. |
Cannot agree more. I did manage to track down germanium transistors once to test the common opinion that their distortion is much sweeter than silicon, and it is true, but it still takes a tremendous amout of tweaking to make a good sounding circuit.
Hmmm, maybe a germanium transistor preamp on a chip power stage would be the ticket... :) |
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| jackinnj |
| modulate the Vadjust pin of an LM317 regulator, |
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| skyraider |
leadbelly,
you meant AC128??
i heard they were good too, the original transistors used in fuzzface. I tried with a few germanium replacements but they were never that good. |
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| leadbelly |
| quote: | Originally posted by skyraider
leadbelly,
you meant AC128??
i heard they were good too, the original transistors used in fuzzface. I tried with a few germanium replacements but they were never that good. |
No, the ones I used I never managed to identify; they probably were oem markings. I just played by trial & error with component ratings to get them to clip in a fuzz face clone.
Are germaniums available new? I'm not sure how to search for them. |
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| skyraider |
you dont get my point:
1. you cant get a NICE 'dirty' sound with a SIMPLE preamp.
2. any distortion from his zoom pedal will outperform any SIMPLE distortion from preamp.
to get that sweet tube distortion from your preamp, it needs lots of heavy tweaking, to the extreme: JRC4558Ds, AC128s, blah blah blah..... |
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| skyraider |
I can never get my hands on the original AC128s.. but older germaniums you have to dig deep in electronic service stores. I read that AC128 is used widely in european products during its service, but heck... I have no luck so far.
And yes, germaniums are available new, but those modern types have too high gain which is unsuitable for FF design. Heard that the best gain values are between 90-120. |
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| skyraider |
leadbelly, have you any experience with TS-9?
Ive built a clone, but im unsure of the original component types, especially the caps used in tone control section. I know they use JRC4558D, though:) |
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| leadbelly |
| Sorry, I have yet to build a tube screamer clone. But there is one site out there that is incredibly comprehensive on tube screamer schematics, including all manufacturer revisions and endless mods. Unfortunately, I lost the link a couple of years ago, and I haven't gotten around to finding it again. It will take a bit of surfing to find it. :) |
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| nobody special |
You guys are way off on this...
| quote: | | Well, I guess I should be more specific. I have a speaker already, some 2-driver car speaker, and I was intending to use the volume control on my guitar and on my Multi-Effect (Zoom 606). I just need some simple schematic that will amplify the sound... it don't have to be a Tube amp, but rather a chip (like TDA2030 or such) amp because it's cheaper and simpler.. |
First- the multieffects units built for guitar generally have distortion (including tube emulation) EQ, compression, cabinet emulation+ effects like reverb, chorus, flange, etc. You can actually plug some of these direct into a recording console and get a decent sound out of them. All the guy really needs is an amp of any kind to drive a speaker. Sure, a tube amp offers a sweet sound, but that is icing on the cake when you're talking about a cheap setup like this. I use a digitech RP1 through a Traynor bass amp (tubes) quite often for my guitar, and it sounds decent (yes, there's much better, but that's beside the point). He doesn't need a preamp either- it's all contained in the effects unit. He would be better off using even a cheap guitar speaker instead of that car speaker- something that rolls off around 5Khz would be appropriate. There has to be a cheap woofer somewhere that fits that description. |
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| ir |
indeed
and as i said all he needs is a 20W LM1875 power amp as per datasheet
only additional component maybe a volume control altho he says he doesn't need one - it's still a good idea tho because turning down the guitar volume reduces the output so any effects pedal won't have enuff signal to do their job properly
anyways.
in reference to my trialing the idea yesterday. i used no preamp. preamps are for girls. (kidding - i need to build a preamp) just whcked the guitar directly into one channel turned it up half started playing. it was sweet through my four 12inch philips fullrange drivers (ideal for guitar/PA stuff ;) )
simply build the amp exactly as the datasheet says to. you mentioned do you need caps on the V+, V-? yes. if it's on the datasheet it should be on your amp. if you've never built one before then your first tiem is no time for experimentation - build a working version THEN experiment if you so choose
this is the amp i used. it was my first LM series amp. as such it's pretty crude. http://oc4free.scalded.net/amplifier/amplifier.html
unfortunately i didn't document much so it's not goign to help you a lot. fortunately however, the new amp i build this week i documented right from the coffee (essential) to the shoving of Metallica thru it. hopefully i'll be finished with it in the next few days and i'll post a page
good luck |
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| leadbelly |
| quote: | Originally posted by nobody special
You guys are way off on this...
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| quote: | Originally posted by ir
indeed
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Actually, I think you guys are way off. If you see the jump in dates of almost a year in the thread, you will see that the discussion was rekindled recently. My posts are not trying to answer the original post from a year ago (I'm sure the poster has built/bought something by now), just discussing guitar amps using chips. |
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| nobody special |
| quote: | Originally posted by ir
indeed
and as i said all he needs is a 20W LM1875 power amp as per datasheet
only additional component maybe a volume control altho he says he doesn't need one - it's still a good idea tho because turning down the guitar volume reduces the output so any effects pedal won't have enuff signal to do their job properly
anyways.
in reference to my trialing the idea yesterday. i used no preamp. preamps are for girls. (kidding - i need to build a preamp) just whcked the guitar directly into one channel turned it up half started playing. it was sweet through my four 12inch philips fullrange drivers (ideal for guitar/PA stuff ;) )
simply build the amp exactly as the datasheet says to. you mentioned do you need caps on the V+, V-? yes. if it's on the datasheet it should be on your amp. if you've never built one before then your first tiem is no time for experimentation - build a working version THEN experiment if you so choose
this is the amp i used. it was my first LM series amp. as such it's pretty crude. http://oc4free.scalded.net/amplifier/amplifier.html
unfortunately i didn't document much so it's not goign to help you a lot. fortunately however, the new amp i build this week i documented right from the coffee (essential) to the shoving of Metallica thru it. hopefully i'll be finished with it in the next few days and i'll post a page
good luck |
I agree... a good way to go. He probably has a master volume on the zoon unit, but I would put one in anyway (a nice big volume knob is much more handy than whatever is on those little mini-effects things).
| quote: | Originally posted by leadbelly
Actually, I think you guys are way off. If you see the jump in dates of almost a year in the thread, you will see that the discussion was rekindled recently. My posts are not trying to answer the original post from a year ago (I'm sure the poster has built/bought something by now), just discussing guitar amps using chips. |
Sorry about that... didn't understand the intent. Maybe a seperate thread would be a good idea. |
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| skyraider |
| ir, do you just plug your guitar into lm1875 directly? or did you go through your effects as preamp? |
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| ir |
when i say no preamp, i mean no preamp
i simply took a phono to RCA cable, plugged on ened into my guitar, the other into the left channel input of my amp. and started playing
then for the effects pedal (Ibanez "Fatcat" distortion) just put the guitar into that, then that into the amp. it's hardly a preamp as i matched to on/off volumes (so it doesn't suddenly get louder when you turn it on)
works fine
i believe most guitar pickups have an impedance of around 150-200K. several thousand turns of wire will do that. Guitar output levels are closer to line level then to Mic so there's no problem there.
a preamp wouldn't hurt. but it's not essential. you could increase the gain of the amp by increasing the feedback resistor (or even maybe using a variable resistor - altho i don't recommend it. altho just like most people posting to this thread, i have no grounds to not recommend it as i've never tried it) |
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| jimbeam |
I recently built a solid-state guitar amp based on a TDA2050 chip, and it's working like a charm, the circuit I used is shown in the chip's datasheet.
Guitar pickups usually are high impedance, so I placed an opamp buffer with 1M input impedance in front of the power amp, plus a tone stack (hi/mid/bass) with volume control.
The poweramp looks a bit like a gainclone, with point-to-point wiring and mounted on an old cpu cooler! Even without any shielding (it's inside a wooden cabinet), the whole setup is very quiet, almost no noticable hum.
Of course this amp will never sound like a tube amp, but it's a very nice clean sounding amp, and if you need distortion, just hook up a pedal. |
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