i have an extra 1875. i just looked up the bridge pickup in my guitar and it says it puts out 425mV. so i just put a pot for one of the gain resistors and set it up so i can clip my like 18V rails? do these chips clip normally or do they have some kind of weird protection thing that sounds odd? i bet i could use it to play grim and frostbitten black metal at least.
i was planing on making that rod elliot graphic equalizer someday...
what i should really do is make a slave, i think that's the right word, to connect to the line out of my real guitar amp, so that i can power a 1x15 cabinet that i want to build as well. but then i have to find a nice tube guy who will fix the line out cos it doesn't seem to be working.
is it possible to use a guitar as a balanced input? pickups love to hum.
i was planing on making that rod elliot graphic equalizer someday...
what i should really do is make a slave, i think that's the right word, to connect to the line out of my real guitar amp, so that i can power a 1x15 cabinet that i want to build as well. but then i have to find a nice tube guy who will fix the line out cos it doesn't seem to be working.
is it possible to use a guitar as a balanced input? pickups love to hum.
Hi.
A LM1875 can be used as a guitar amp indeed. I've never heard a LM-chip amp clipping but I also suspect it would not give a nice overdriven sound. The nice thing is that youy can very easely use a combination of voltage and current drive to increase the output-impedance. See Rod Elliots website for more info on that: www.sound.au.com
To prevent the chip from clipping you could use a couple of 12V Zeners in series across the feedback resistor. This will give a much nice sound when you overdrive the amp.
For real metal-overdrive you will need something like 40dB of gain beyond linear amplification. A fair bit of bass roll-of is needed before overdrive (6db/oct @ 1KHz) if you don't wan't to sound like a fart. And offcourse a EQ section is needed if you don't want you guitar sound like a funky-jazz instrument. I prefer the Fender type (see GMarts website, from Rod Elliots links)
Best option is indeed to uses the LM1875 as a power amp, feeding it from a preamp, or other power amp.
The Humbucker elemets are allready in a balanced kind of topology, single coil element will allways hum more.
I hope I don't come on to strong, but I love building guitar amps.
Goodluck,
Thijs
A LM1875 can be used as a guitar amp indeed. I've never heard a LM-chip amp clipping but I also suspect it would not give a nice overdriven sound. The nice thing is that youy can very easely use a combination of voltage and current drive to increase the output-impedance. See Rod Elliots website for more info on that: www.sound.au.com
To prevent the chip from clipping you could use a couple of 12V Zeners in series across the feedback resistor. This will give a much nice sound when you overdrive the amp.
For real metal-overdrive you will need something like 40dB of gain beyond linear amplification. A fair bit of bass roll-of is needed before overdrive (6db/oct @ 1KHz) if you don't wan't to sound like a fart. And offcourse a EQ section is needed if you don't want you guitar sound like a funky-jazz instrument. I prefer the Fender type (see GMarts website, from Rod Elliots links)
Best option is indeed to uses the LM1875 as a power amp, feeding it from a preamp, or other power amp.
The Humbucker elemets are allready in a balanced kind of topology, single coil element will allways hum more.
I hope I don't come on to strong, but I love building guitar amps.
Goodluck,
Thijs
Yes, I think that would be the a very good option. I didn't know Sovteks had a line-out... it is taken from the preamp? post EQ?, post mastervolume? is it a FX-loop or true line-out? post output-transformer?
I thought the Sovteks do have a traditional presence controll which controll the amount high-frequenxy feedback around the output stage. This can be incorperated with a LM1875 very easy. I don't think it will sound bright, but maybe a little lack of highs: hende the presence controll.
Regards,
Thijs
BTW They are excelent amp fot the money!
I thought the Sovteks do have a traditional presence controll which controll the amount high-frequenxy feedback around the output stage. This can be incorperated with a LM1875 very easy. I don't think it will sound bright, but maybe a little lack of highs: hende the presence controll.
Regards,
Thijs
BTW They are excelent amp fot the money!
yeah, they are good amps.
i found the schematic
http://www.chris-mohrbacher.com/tech/sovtek/Mig60.jpg
i don't understand what's going on in this crazy tube stuff.
i found the schematic
http://www.chris-mohrbacher.com/tech/sovtek/Mig60.jpg
i don't understand what's going on in this crazy tube stuff.
Hi travis,
Well it looks like the line-out is just a scaled down version of the speakers output, with some strange filtering. The filter is set a bit odd, I don't understand why. Just use it a tell us how it sounds.
Don't forget to use a dummy load if you disconnet the speakers from your tube-amp, and you will need a volume controll because the line-out is pretty hot.
cheers,
Thijs
Well it looks like the line-out is just a scaled down version of the speakers output, with some strange filtering. The filter is set a bit odd, I don't understand why. Just use it a tell us how it sounds.
Don't forget to use a dummy load if you disconnet the speakers from your tube-amp, and you will need a volume controll because the line-out is pretty hot.
cheers,
Thijs
Sorry to dig up this old thread.
I just find these chipamps great for:
1. Bass amps, if powerful enough. The 1875 doesn't qualify.
2. Small practice amps. Some fender models use the TDA 2030 (!)
AFAIK the 1875 is NOT SPike-protected.
Also if you have a good amp simulator it would be the best.
A lot of the character of guitar amps comes from cone breakup as well. some of the poorer combos fart rather than breakup. Good ditortion is impossible to achieve on SS, unless it is done before amplification.
Maybe a tube/1875 hybrid concept would be very good here. Which would be the point of using the Sovtek line out...
I just find these chipamps great for:
1. Bass amps, if powerful enough. The 1875 doesn't qualify.
2. Small practice amps. Some fender models use the TDA 2030 (!)
AFAIK the 1875 is NOT SPike-protected.
Also if you have a good amp simulator it would be the best.
A lot of the character of guitar amps comes from cone breakup as well. some of the poorer combos fart rather than breakup. Good ditortion is impossible to achieve on SS, unless it is done before amplification.
Maybe a tube/1875 hybrid concept would be very good here. Which would be the point of using the Sovtek line out...
Have to ask...
Just wondering...thinking about re-building an old Ampeg (mid 60's era). Never really liked the way it sounds. Someone has replaced the speaker with something from Radio Shack some years ago. Speaker still playes, but tonality...
If I was to replace the speaker, why couldn't I use an "normal" "full range" speaker?
Also, been playing guitar for only a few years. And no one has been able to answer me about why every amp I see, has the rear of the cabinet open...speaker not in a sealed/vented type chamber?
Thanks,
Rino
Just wondering...thinking about re-building an old Ampeg (mid 60's era). Never really liked the way it sounds. Someone has replaced the speaker with something from Radio Shack some years ago. Speaker still playes, but tonality...
If I was to replace the speaker, why couldn't I use an "normal" "full range" speaker?
Also, been playing guitar for only a few years. And no one has been able to answer me about why every amp I see, has the rear of the cabinet open...speaker not in a sealed/vented type chamber?
Thanks,
Rino
Guitar amps need a speaker that rolls off in the 5Khz range to sound right. It will be VERY buzzy if you use any kind of distortion through a full range speaker. That, and guitar speakers are made to have a certain amount of cone "breakup". You're better off getting a speaker made for guitar.
Whilst I agree with the advice that you are better off with a guitar speaker in general, I don't agree with the comments on how a guitar sounds through a full-range speaker.
I, my sons and several of my gigging friends regularly use my designs cabs that use---full-range speakers. These are driven by my design valve amps and sound superb. The amp design are class A and no feedback so they can be overdriven hard without the nasties appearing that typical guitar amps produce.
It's true that a typical modern guitar amp driven into a full range speaker can sound horrible - for much the reasons given but it doesn't have to be so and you shut off a whole universe of superb tone if you just stick to conventional wisdom...
ciao
James
I, my sons and several of my gigging friends regularly use my designs cabs that use---full-range speakers. These are driven by my design valve amps and sound superb. The amp design are class A and no feedback so they can be overdriven hard without the nasties appearing that typical guitar amps produce.
It's true that a typical modern guitar amp driven into a full range speaker can sound horrible - for much the reasons given but it doesn't have to be so and you shut off a whole universe of superb tone if you just stick to conventional wisdom...
ciao
James
To each his/her own! That's one of the best things about playing guitar- everyone has their own style. You have to admit though, that 99% of guitarists would NEVER play through full range cabinets (unless you have a tone-shaping circuit in the amp to simulate a guitar cabinet).
James D. said:
...Non Est Disputandum...
yeah - we might argue the odd percentage point but really that's moot...
Most wouldn't because they don't understand how to set their head up to do so and what tone variations that would open up...
And it really doesn't matter if they are happy with their sound.
BUT when discussing the engineering of guitar amplifiers and cabs we should care and try to understand the differences and what causes them...
ciao
James (jumping off his soap box)
yeah - we might argue the odd percentage point but really that's moot...
Most wouldn't because they don't understand how to set their head up to do so and what tone variations that would open up...
And it really doesn't matter if they are happy with their sound.
BUT when discussing the engineering of guitar amplifiers and cabs we should care and try to understand the differences and what causes them...
ciao
James (jumping off his soap box)
You're absolutely correct, sir. (now what do we have behind door number 1
)Understanding that when a signal is clipped hard, as in any guitar amp (tube or solid state) on the distortion channel, it generates amazing amounts of harmonics, which in any normal guitar amp from the last 50 years, are rolled off by the speaker. In fact, many guitar amps use a capacitor in the high gain stages to turn off some of the high end before it even gets to the speaker!
You didn't quote me completely. If you either design a preamp with built in cabinet simulation, or use one of the many tone boxes (yuck!) out there by digitech, etc. you can run direct into the board, direct into the PA, whatever, which is basically the same, I assume, as what you're doing. In other words, electronics are doing the same thing, basically, as the speaker cabinet. It's not the best approach for all out raw tone though. Let's face it- tone was defined by rock and jazz legends from the past, working with and abusing what they had. At least in America, a good guitar tone means tubes played through Celestions (or something similar). This doesn't mean necessarily that someone shouldn't dare to break the rules. Many have successfully. But, the greatest ones have always stayed close to that old formula. Why do you think that is?
Don't think that I'm telling you that you're wrong for what you're doing. I think it's cool that you're doing your own thing. But when someone gets on here and asks why their amp doesn't sound right, it would be stupid not to stick to what will give proven results- not 1 guy and his band's opinion of what sounds good. Chances are very good that he will be happy with a good guitar speaker, and that a fullrange will sound like trash to him in that application (as it does to nearly everybody else who has tried it).
Maybe you're the next big thing and I just missed it, but I'll stick with ratty old non-fullrange speakers.
Oh, and by the way- I did build an amp once that used a bullet tweeter that would switch on by relay on the clean channel (but it was a VERY clean channel).
Actually a lot of the cheaper amps just have solid state output stages and also with IC´s.
What makes a few of them special in sound is the preamp (which should be tube IMO).
You´ll find loads of schematics on the net about some cool commercial products from Marshall and the sort.
You might get a real nice sound finding the appropriate preamp.
The question is how far that would take you as the LM1875 won´t put out much watts and will probably have problems driving a 15" and being louder than even some jazz-drummer.
If I was to build a guitar amp I´d use a bridged-parallel gainclone to get more power.
Go ahead build a nice preamp and try your LM1875.
You can still exchange the output stage.
Cheers
Jens
Talking about metal:
When I was still playing metal I used the BOSS Metal Zone.
Ever tried that pedal?
I wouldn´t use it anymore as I´m going for tuby sounds only but for metal it was brilliant.
What makes a few of them special in sound is the preamp (which should be tube IMO).
You´ll find loads of schematics on the net about some cool commercial products from Marshall and the sort.
You might get a real nice sound finding the appropriate preamp.
The question is how far that would take you as the LM1875 won´t put out much watts and will probably have problems driving a 15" and being louder than even some jazz-drummer.
If I was to build a guitar amp I´d use a bridged-parallel gainclone to get more power.
Go ahead build a nice preamp and try your LM1875.
You can still exchange the output stage.
Cheers
Jens
Talking about metal:
When I was still playing metal I used the BOSS Metal Zone.
Ever tried that pedal?
I wouldn´t use it anymore as I´m going for tuby sounds only but for metal it was brilliant.
The preamp is responsible for the basic sound of the amp, but it's the output stage that makes a great amp. I didn't realize this at first and thought it wouldn't matter what you used behind the right preamp. I remember years ago telling one older guy this at a music store, and him just shaking his head and giving me a look like I was clueless. He was right! Some of the suggestions on modifying the output impedance are good ones. I think it could sound good if you like a punchy and clean output stage sound, but you just can't beat a good tube output stage with a tube rectifier. I have heard some solid state preamps run through tube output stages that would amaze you. For you metal heads- try what Joensd was saying with a Boss pedal, only through a p/p tube output stage. Killer metal sounds!
Thanks for the advice guys! I thought that it was a problem, it just sounded off...if you know what I meen. The only thing though...when I play my Les Paul Studio through it (cranked of corse), if I hit the right notes (unfortunately only happens once in a blue moon) when playing some Jimi Page, it really really sounds good. But only then...strange eh. Sounds very accurate...I wonder if Mr. Page was playing around with things to get his famous sound? Hummmm.
Rino
Rino
Assuming you're looking for a clean sound, the thing that will make the most difference is input impedance. Most passive pickups have a very inductive output, meaning there's a big loss of high frequencies when it's driving a typical 47K line input. Upping this to 1M or 2M gives a much better sound, although this might lead to other problems with the LM1875 (noise and DC offset, for instance).
Cheers
IH
Cheers
IH
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