For the Rodd Elliott projects, try to buy the PCB from him.
He deserves it, and it's one way to help him maintain his *very* useful site.
The PCB is inexpensive and sending it by mail inside an envelope costs little.
Otherwise, design your own, but for "just one" it will be faster and cheaper to just buy it.
As of power, 100W is already a lot for a Guitar amp.
I'd MUCH prefer to have a 100W power amp and 2 12" 60/70W *guitar* speakers such as a Celestion/Eminence/Jensen to have a couple of 300W PA/HiFi speakers .
The speaker "errors" are part of the Guitar sound.
The power amp you already made is good enough for guitar; if you want you can use it "Stereo", with each channel driving one speaker .
He deserves it, and it's one way to help him maintain his *very* useful site.
The PCB is inexpensive and sending it by mail inside an envelope costs little.
Otherwise, design your own, but for "just one" it will be faster and cheaper to just buy it.
As of power, 100W is already a lot for a Guitar amp.
I'd MUCH prefer to have a 100W power amp and 2 12" 60/70W *guitar* speakers such as a Celestion/Eminence/Jensen to have a couple of 300W PA/HiFi speakers .
The speaker "errors" are part of the Guitar sound.
The power amp you already made is good enough for guitar; if you want you can use it "Stereo", with each channel driving one speaker .
Hi !
I know that we must support sites like this and I respect the work of Rodd Elliott, mind 🙂
I want few entries (therefore few preamps), example 3 or 4 : pcb cost 18$*4 without shipping. For me, isn't inexpensive. I fully agree that I can't designed my pcb for just few units ... 😛
It is still my "first" projects in audio (warning, I can build a big project with all the security rules, I'm not a beginner) but I think it takes several *years* months for unterstand all the details of a good diy audio build. For the moment, I want to build something like cheap/powerfull. After some projects, I want make good preamp/amp/speakers/ect but it's an another budget, and it's not of today 😉
But don't worry, within a few projetcs, we can build together a very good amplifier, not powerfull but the greater sound
Is anyone can explain me the bridge and impedance rules ?
So with my amp, 2*100W/8R, if I load in 4R, how to calculate the power ? I think it's 100*1.7~W but I'm not sure ... 😱 And, if I bridged my amp for a mono output, it's exactly 2*100W or a little less ? (I think it's exactly 200w ...)
Thanks
I know that we must support sites like this and I respect the work of Rodd Elliott, mind 🙂
I want few entries (therefore few preamps), example 3 or 4 : pcb cost 18$*4 without shipping. For me, isn't inexpensive. I fully agree that I can't designed my pcb for just few units ... 😛
It is still my "first" projects in audio (warning, I can build a big project with all the security rules, I'm not a beginner) but I think it takes several *years* months for unterstand all the details of a good diy audio build. For the moment, I want to build something like cheap/powerfull. After some projects, I want make good preamp/amp/speakers/ect but it's an another budget, and it's not of today 😉
But don't worry, within a few projetcs, we can build together a very good amplifier, not powerfull but the greater sound
Is anyone can explain me the bridge and impedance rules ?
So with my amp, 2*100W/8R, if I load in 4R, how to calculate the power ? I think it's 100*1.7~W but I'm not sure ... 😱 And, if I bridged my amp for a mono output, it's exactly 2*100W or a little less ? (I think it's exactly 200w ...)
Thanks
In a theoretically perfect current source amp, if it gives 100 Watts into eight ohms, it'll give 200 into four, 400 into two and so on until catching fire.
With real amps, you protect them against excess current, their power supplies drop in voltage with extra load, temperature sensing brings down the gain if they overheat… there is no equation which will allow you to precalculate power. Some eight ohm amps are current limited to give maximum current into eight ohms, so they actually give less power into four (though, considering the actual impedance curve of a loudspeaker that claims to be 8Ω, this is not very fair) – others will give full voltage peaks into two ohms, temporarily.
This is exactly the same with bridge mode. Each output sees half of the load, so is trying to give twice the current (I have an amp that will drive into 1Ω in bridge mode, off ±65 volt rails. I try and organise someone else to lift it).
You should be able to find specifications on your amp. If it doesn't give details for four ohms, don't use it, even if it claims short circuit protection. Cooking amps does not increase their reliability or lifetime.
With real amps, you protect them against excess current, their power supplies drop in voltage with extra load, temperature sensing brings down the gain if they overheat… there is no equation which will allow you to precalculate power. Some eight ohm amps are current limited to give maximum current into eight ohms, so they actually give less power into four (though, considering the actual impedance curve of a loudspeaker that claims to be 8Ω, this is not very fair) – others will give full voltage peaks into two ohms, temporarily.
This is exactly the same with bridge mode. Each output sees half of the load, so is trying to give twice the current (I have an amp that will drive into 1Ω in bridge mode, off ±65 volt rails. I try and organise someone else to lift it).
You should be able to find specifications on your amp. If it doesn't give details for four ohms, don't use it, even if it claims short circuit protection. Cooking amps does not increase their reliability or lifetime.
ripX
have you looked at the Ax84
if you look online/netsearch this a popular diy guitar amp design and it seems to have a fair community/following.
also a bassman(fender) type design in my opinion is a good all around contender just copy something like that and enjoy!
i don't know if you have any objection to a tube design or is solid state a requirement
conseil disponible en francais
have you looked at the Ax84
if you look online/netsearch this a popular diy guitar amp design and it seems to have a fair community/following.
also a bassman(fender) type design in my opinion is a good all around contender just copy something like that and enjoy!
i don't know if you have any objection to a tube design or is solid state a requirement
conseil disponible en francais
Last edited:
Hi,
@turk 182 : Thanks for your advise, but I search a chip amp for a cost question 😉
@chrispenycate : Thanks ! In the original post of the amp, it is write "And When connected to the bridge adapter with output altitude of about 400 watts is incredible." = You can bridge this into 4 ohms ? 😕 I don't know ... and nothing in the datasheet for this information !
And, load an amp into a bad impedance can burn it, nay a good psu ?
@turk 182 : Thanks for your advise, but I search a chip amp for a cost question 😉
@chrispenycate : Thanks ! In the original post of the amp, it is write "And When connected to the bridge adapter with output altitude of about 400 watts is incredible." = You can bridge this into 4 ohms ? 😕 I don't know ... and nothing in the datasheet for this information !
And, load an amp into a bad impedance can burn it, nay a good psu ?
Anyway, more than 100W for a guitar amp is too much, believe me.
Bridging them is even more unnecessary.
One of (if not *the*) most popular amps in the World is the Peavey Bandit: 60W , 1x12" .
There are hundreds of similar amps , used and sold by the truckload: Crate/Laney/Fender/Marshall .
Why?: because the concept works.
So a 100W , 2x12" is not overkill, but a very practical solution.
Beyond that it's unneeded.
Bridging them is even more unnecessary.
One of (if not *the*) most popular amps in the World is the Peavey Bandit: 60W , 1x12" .
There are hundreds of similar amps , used and sold by the truckload: Crate/Laney/Fender/Marshall .
Why?: because the concept works.
So a 100W , 2x12" is not overkill, but a very practical solution.
Beyond that it's unneeded.
Thanks, so the amp which I have build it's working for this application in 100w stereo 8 ohms ? 🙂
well maybe something hybrid tube pre mos output like a line 6
because to me it's a tone vs cost question/quest oui ou non?!
why stereo for a guitar amp?
because to me it's a tone vs cost question/quest oui ou non?!
why stereo for a guitar amp?
Yes.
Get 2 12" *guitar* speakers, one for each channel, and you'll be *happy*.
Being in Europe, I think that Celestion or Jensen might be the best choices, but try to find the Italian SICA speakers.
(Between you and me, they are the ones who actually make the Italian Jensens, so the "Sica" branded are basically the same, without the "famous" label .... and the "famous " price 😉 ... but *I* didn't tell you 😉 )
Get 2 12" *guitar* speakers, one for each channel, and you'll be *happy*.
Being in Europe, I think that Celestion or Jensen might be the best choices, but try to find the Italian SICA speakers.
(Between you and me, they are the ones who actually make the Italian Jensens, so the "Sica" branded are basically the same, without the "famous" label .... and the "famous " price 😉 ... but *I* didn't tell you 😉 )
haha thanks 😛
Like JMFahey, a stereo amps for 2 speakers. It's better than bridge and burn the amp ... I think ...
I'll think about it, and I tell you my build and steps, if I have questions I come to you 😀
Thanks for all guys
Like JMFahey, a stereo amps for 2 speakers. It's better than bridge and burn the amp ... I think ...
I'll think about it, and I tell you my build and steps, if I have questions I come to you 😀
Thanks for all guys
Hi,
@turk 182 : Thanks for your advise, but I search a chip amp for a cost question 😉
@chrispenycate : Thanks ! In the original post of the amp, it is write "And When connected to the bridge adapter with output altitude of about 400 watts is incredible." = You can bridge this into 4 ohms ? 😕 I don't know ... and nothing in the datasheet for this information !
And, load an amp into a bad impedance can burn it, nay a good psu ?
When I design an amp it won't catch fire – but occasionally 'portable' isn't the best description. Acoustic music generally contains short-term peaks at many times the average power of the music. Tube amps (amplis a lampe, valve amps) are superb for reproducing these, and some transistor amps are given a similar capacity; which generally renders them vulnerable to output device failure if the 'peak' turns out to be a plateau. Then mixing engineers like (I hang my head in shame) me remove all this lovely dynamic range so the music sounds as loud as possible on a car stereo. (and dead.)
But the power curve for an electric guitar, particularly one running into distortion, is not the same as an orchestral mix. So, yes, I have repaired amps that have not merely smoked (common) but have had flames inside. If this should happen to yours, always pull the power cord out, either of the amp or the wall, before tipping beer through the ventilation grill to extinguish it.
It is rare that a manufacturer of an amplifier that will give 2X200 Watts into 4 ohms, or bridge to 400, will rate it as a hundred watt stereo. Not that it isn't, nor that that isn't plenty of power for a guitar unless you're doing a stadium gig without PA, but there's a definite tendency to rate at absolute maximum output.
And, for whoever it was who asked "why stereo?":- it's so if half of the amp catches fire, you can go on playing the other half while somebody fetches the fire extinguisher (on stage there are other advantages).
you made me laugh man 😀
I do not want that my amp catch fire, so if I choose this amp, I load into 8 ohms in stereo, and it's all 🙂
If I'm not mistaken, it's easier to bridge two mono separe amps ? 🙄 But with a stereo amp it's not advisable, it's right ?
I'm in thread with a electronician for him to teach me how to make a pcb design ! I think this will be easier for make good amps/preamps without big spending ... 🙂
Thanks
I do not want that my amp catch fire, so if I choose this amp, I load into 8 ohms in stereo, and it's all 🙂
If I'm not mistaken, it's easier to bridge two mono separe amps ? 🙄 But with a stereo amp it's not advisable, it's right ?
I'm in thread with a electronician for him to teach me how to make a pcb design ! I think this will be easier for make good amps/preamps without big spending ... 🙂
Thanks
sorry
i think point to point wiring is easier and cheaper and the problems of disposal of the chemicals with making pcb's is another story altogether!
it might be different if you where looking to make several not just one.
isn't a stereo amp really just two mono amps linked by a balance control all in one box!?!?
as far as bridging goes design and real world stability and matched or close tolerance in operation are more significant to successful bridged operation.
i think point to point wiring is easier and cheaper and the problems of disposal of the chemicals with making pcb's is another story altogether!
it might be different if you where looking to make several not just one.
isn't a stereo amp really just two mono amps linked by a balance control all in one box!?!?
as far as bridging goes design and real world stability and matched or close tolerance in operation are more significant to successful bridged operation.
je ne suis pas toujours 100% serieux, c'est vrai.RIP said:
Reality check; when we say "stereo amp", we are all talking about a two channel power amplifier, with no preamplifier and only volume controls, not a full integrated HiFj amp with input selectors, tone controls, the works? Either can catch fire, although the latter is more prone to it😉.
The former frequently has a switch to put it into bridge mode (and presumably as one amp's going down while the other goes up the power supply likes it). The latter is a touch more difficult to bridge (oh, not beyond the capacity of anyone here) requiring polarity inversion of the signal, and a slight understanding of what you're doing. Two mono amps demand no tone control (so phase information doesn't get mixed up) and reasonable gain matching, but a dB or two of mismatch is not all that critical - just drops your final power a touch. Not like matching on balanced inputs.
Most stereo amps run off one power supply for the two halves so you can be confident of reference ground between the two halves; when you have two independent amps making sure of ground currents flowing where you want them (trust grounding through power cords? Connect two output 'cold' terminals together?) and with ground currents of several ampères (I was going to use the standard contraction "amps" then thought how, as we are also using that as a contraction for "amplifiers", confusing this could become. Pedantic, ain't I?) instability at several frequencies became a very real risk. And RF instability is one of the chief culprits in setting fire to amps (and tweeters. And cooking voice coils in bigger drivers. None of which we want, thank you.)
Using a HiFi amp at its maximum rated power continuously, Hendrix style, is likely to cause it to overheat, so running it into twice it's suggested minimum impedance would seem sensible (Hendrix, with amps that were designed to be overdriven, used to cycle heads between numbers to give them time to recover - another roady I knew with another band used to wear asbestos gloves on stage and, during the spiel between numbers pull out and change all the EL34s, whose anodes would be glowing bright orange red. There are certain guitarists who think a volume control is a switch.)
Point to point? I wouldn't use anything else on tubes, it's quite usable on discrete transistors but for prototyping ICs veroboard (is that "vector board" in modern speak? Not, admittedly as flexible to change, as after a few resolderings the copper starts to peel and things get really messy, but gives a mechanical matrix in which to breadboard.
Hi guys !
When you look for a pcb and it costs 5 to 150$ ... sure, for 5$, not the time to design and make the pcb, but for 150$ it's an another story. Anyway, even the preamp you advise me, I can't pay 18$ + shipping each board. And I think designed is the way to learn what we do and improve. I don't know if in your country chemicals are easy to delete but in france it's free and easy (and green) so no problems 😀
Yes, stereo amp = 2 channels board ... 🙄 In fact, the bridge principe for two board (is I have good understand the simplest way for more power easy) can be find here no ? DIY BPA300 6x LM3886 300W audio Amplifier I have look, I think is a very good thread ... 😎
And, you said "Using a HiFi amp at its maximum rated power continuously, Hendrix style, is likely to cause it to overheat" ... so, if I am the way of your sentence, a big chip amp is better for an guitar amp.
Since bigger power = amp less stress for the same load = less heat = bigger lifetime ..?
Thanks
When you look for a pcb and it costs 5 to 150$ ... sure, for 5$, not the time to design and make the pcb, but for 150$ it's an another story. Anyway, even the preamp you advise me, I can't pay 18$ + shipping each board. And I think designed is the way to learn what we do and improve. I don't know if in your country chemicals are easy to delete but in france it's free and easy (and green) so no problems 😀
Yes, stereo amp = 2 channels board ... 🙄 In fact, the bridge principe for two board (is I have good understand the simplest way for more power easy) can be find here no ? DIY BPA300 6x LM3886 300W audio Amplifier I have look, I think is a very good thread ... 😎
And, you said "Using a HiFi amp at its maximum rated power continuously, Hendrix style, is likely to cause it to overheat" ... so, if I am the way of your sentence, a big chip amp is better for an guitar amp.
Since bigger power = amp less stress for the same load = less heat = bigger lifetime ..?
Thanks
that 'big' chipamp might be great
but I wouldnt bridge 2 channels
with guitar you have little use of balanced signal
unless for a mixer/PA/recording
neither would I use a stereo amp
you risk all sorts of things
noise, hum, or phase problems
you gain more but using more speakers
one mono amp
and 8x 10" 😀
I have learned the lesson myself....keep it simple
but I wouldnt bridge 2 channels
with guitar you have little use of balanced signal
unless for a mixer/PA/recording
neither would I use a stereo amp
you risk all sorts of things
noise, hum, or phase problems
you gain more but using more speakers
one mono amp
and 8x 10" 😀
I have learned the lesson myself....keep it simple
I don't find bridge amps excessive complexity; mature technology, we've been using them since the sixties, they give extra volts without expensive components, and with the increased power rating of loudspeakers since my youth (I put it down to adhesives technology) you need that extra voltage to push the speakers to their limits. And not bringing the speaker current through your ground, but directly from the power rails eliminates all sorts of potential grounding problems.
Putting on extra speakers is friendlier to the individual drivers, but needs more current. With chip amps you can't just bung on a few more output transistors (and emitter resistors, to take up gain differences); it's whole new amps.
And what scares me faeces-free about that article is the casual paralleling up of entire amplifiers, negligible output impedance, the slightest difference in gain causing currents to circulate between amps – OK, 0.2 ohm series resistors, not really negligible impedance, a straightforward response to a problem of limited precision.
As he was using RCA connectors, I assume the only reason for the balancing board was polarity inversion for the bridging (I would have put XLRs on it and used balanced in, but that's too many years of studio, live and broadcast talking). Strange he didn't spot that with a chip amp like that bridging is ultra simple (you merely sum the outputs and compare them with zero).
He says in the article the heatsinks run hot on loud music, but doesn't say how hot (run a fan in series with the power supplies or make a pot of tea hot?). Still, the chips are supposed to be thermally as well as current protected.
How would I have done it? Nastily, I fear. rely on feedback to get rid of distortion products rather than design nicely linear. Great big heatsinks, with the chipamp and a load of complementary parallel pairs of power transistors. Still bridge, with smallish series resistors between chip and speaker, feedback from speaker end. When enough voltage across series resistor, transistors start taking extra current. Trust the chipamp for current limitation (oh takes a little while with resistor values) and thermal shutdown. Low powers, chipamp does all the work, high powers you're too deaf to hear crossove distortion. Not elegant, but loud.
Putting on extra speakers is friendlier to the individual drivers, but needs more current. With chip amps you can't just bung on a few more output transistors (and emitter resistors, to take up gain differences); it's whole new amps.
And what scares me faeces-free about that article is the casual paralleling up of entire amplifiers, negligible output impedance, the slightest difference in gain causing currents to circulate between amps – OK, 0.2 ohm series resistors, not really negligible impedance, a straightforward response to a problem of limited precision.
As he was using RCA connectors, I assume the only reason for the balancing board was polarity inversion for the bridging (I would have put XLRs on it and used balanced in, but that's too many years of studio, live and broadcast talking). Strange he didn't spot that with a chip amp like that bridging is ultra simple (you merely sum the outputs and compare them with zero).
He says in the article the heatsinks run hot on loud music, but doesn't say how hot (run a fan in series with the power supplies or make a pot of tea hot?). Still, the chips are supposed to be thermally as well as current protected.
How would I have done it? Nastily, I fear. rely on feedback to get rid of distortion products rather than design nicely linear. Great big heatsinks, with the chipamp and a load of complementary parallel pairs of power transistors. Still bridge, with smallish series resistors between chip and speaker, feedback from speaker end. When enough voltage across series resistor, transistors start taking extra current. Trust the chipamp for current limitation (oh takes a little while with resistor values) and thermal shutdown. Low powers, chipamp does all the work, high powers you're too deaf to hear crossove distortion. Not elegant, but loud.
Hi, your informations are very cool guys, thanks ! 😀
For the BPA 300, the project is interesting in so far as there are 2 boards, very cheap components, and 4 ohms 300w output ... For the DRV134 board, I have not understand if it's a usefull operation or not for a guitar amp ... sorry 🙁
I think I will first decide me for speakers ! After, I can choose a project that bests fits for me. And by then, I could certainly draw my pcb myself, which can further expand the list of possibilities !
For the speaker, I have an idea ! Not the best, I know, I'm not a genious ... 😛
I can buid a very powerfull amp and preamp's with transparent sound and *relatively* cheap speakers. With this, I can notify the police and all the people of my town which I build beautiful amps myself 😀 and
need to host parties guitars in cafes !
And, after, I can build a little but very great sound amp and preamp *and speaker* for my home when I want to play without waking everyone !
Finaly, I could plug the little great amp on the very big transparent amp for make a very big great sound ...? 🙄
Thanks !
For the BPA 300, the project is interesting in so far as there are 2 boards, very cheap components, and 4 ohms 300w output ... For the DRV134 board, I have not understand if it's a usefull operation or not for a guitar amp ... sorry 🙁
I think I will first decide me for speakers ! After, I can choose a project that bests fits for me. And by then, I could certainly draw my pcb myself, which can further expand the list of possibilities !
For the speaker, I have an idea ! Not the best, I know, I'm not a genious ... 😛
I can buid a very powerfull amp and preamp's with transparent sound and *relatively* cheap speakers. With this, I can notify the police and all the people of my town which I build beautiful amps myself 😀 and
need to host parties guitars in cafes !
And, after, I can build a little but very great sound amp and preamp *and speaker* for my home when I want to play without waking everyone !
Finaly, I could plug the little great amp on the very big transparent amp for make a very big great sound ...? 🙄
Thanks !
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