Again, you're talking about added expensive for little reason or advantage, and quite probably lowering the audio quality (top quality audio specifically has NO protection for that very reason).
What's wrong with RMS watts?, it's the standard method, easy to test, and easily understood. Peak is a ludicrous idea though, as are the far worse types used ('400W' PC amp fed from a 12V 1A wallwart for example, or almost all car amps).
I drew the printed preamplifier for bass guitar Albert Kreuzer I will fulfill my system because I do not put across his.
Now I think the amplifier!
Please post some sound clips of that preamp once it is done. I am just finishing up my most recent bass preamp build and am always keen to hear other designs.
Ok, no problem!
I'm also slightly modify the printed to put in place of J201 BF245 circuit.
In the meantime here are some sound examples of my sound bank (MAO) of my Rickenbacker!
http://www.fruityclub.net/medias/3/9/39520/4001_Fingered1.mp3
http://www.fruityclub.net/medias/3/9/39520/4001_Fingered2.mp3
http://www.fruityclub.net/medias/3/9/39520/4001_Picked1.mp3
http://www.fruityclub.net/medias/3/9/39520/4001_Picked2.mp3
http://www.fruityclub.net/medias/3/9/39520/4001_Slap.mp3
Regards!
There are a lot of high power hi-fi FET output amp circuits that really don't perform that well in deep clipping. Especially look out for very high gain front ends that can put all the way up to protection clamp voltage on the output FETs after saturation. The VAS has to discharge that voltage to return the output to linear operation and that's where ringing and ugly notches in the signal can happen. It's not a huge issue when hi-fi listening may try to stay at -3dB max anyway.
For bass guitar you are unlikely to purposefully drive the power amp to clipping, but it shouldn't make seriously foul noises or self destruct if it happens. Checking out your circuit in spice is helpful.
In the end it's probably better to use "simple" input and driver circuits because they tend to overdrive the output stage less, recovering from clipping better without clamps everywhere, and you really don't need less than .01% harmonic distortion anyway, so long and the high odd harmonics aren't prevalent. You can also play tricks like making sure the output stage supply voltage is always high enough to keep the power transistors from saturating before the driver stage runs out of voltage drive. This sacrifices some available power but it works.
For bass guitar you are unlikely to purposefully drive the power amp to clipping, but it shouldn't make seriously foul noises or self destruct if it happens. Checking out your circuit in spice is helpful.
In the end it's probably better to use "simple" input and driver circuits because they tend to overdrive the output stage less, recovering from clipping better without clamps everywhere, and you really don't need less than .01% harmonic distortion anyway, so long and the high odd harmonics aren't prevalent. You can also play tricks like making sure the output stage supply voltage is always high enough to keep the power transistors from saturating before the driver stage runs out of voltage drive. This sacrifices some available power but it works.
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Amen brother.
I have been successfully building and selling SS Bass amps for over 40 years now, always very simple "by the book" Lin type amplifiers.
Nobody ever complained about not meeting Hi Fi specs, quite the contrary, they are considered by musicians as being extraordinarily clean.
I had to introduce mild "curve bending" circuits between preamp and power amp to get a few % of mainly even order harmonics and further distort by using undercompensated FET limiters.
I have been successfully building and selling SS Bass amps for over 40 years now, always very simple "by the book" Lin type amplifiers.
Nobody ever complained about not meeting Hi Fi specs, quite the contrary, they are considered by musicians as being extraordinarily clean.
I had to introduce mild "curve bending" circuits between preamp and power amp to get a few % of mainly even order harmonics and further distort by using undercompensated FET limiters.
So far the best circuit I have for bass guitar looks like the VSSA except it has a triple EF with ten pairs of bipolars on the output. (it drives 2.66 ohms) There are current sources at the input transistor emitters for bias, to allow direct coupling, but those are loaded by 20 ohms to ground. No part of the circuit flies off into space when the output clips, and no diode clamps are required anywhere. Before arriving at this circuit I tried to go all "hi fi", even got discouraged and thought I might use an old Hafler driver board just to get it up and running, until sim'ing it and not liking any part of the performance I saw. Still looking for an easy way out, I then simmed a recent Ampeg and I think it was a Carvin design, still not being impressed. The beefed VSSA type circuit has smoothly rounded entry and exit from clipping and gets a simmed .0007% distortion at half power, with regulated 60 volt VAS supply and 70 volt (unloaded) rectifier EF supply. I messed around with resistor values quite a bit to minimize distortion but it began to seem a little silly since I'll never play without an overdrive circuit ahead of the amp.
Hi everyone!
Thank you for all the answers but I'm at same point!
In searching the net I found this schematic that seems interesting to me but before I get into the design of the print card , I'd like to have some opinions.
Bass guitar super bridge amplifier 200 watt. | Eleccircuit.com
Regards!
Thank you for all the answers but I'm at same point!
In searching the net I found this schematic that seems interesting to me but before I get into the design of the print card , I'd like to have some opinions.
Bass guitar super bridge amplifier 200 watt. | Eleccircuit.com
Regards!
It will probably work, and in fact each half looks very much like one of my standard power amps (so called Lin type amp) , but:
1) 200W/8 ohms? NO WAY
Max peak voltage on the speaker would be 52V , and that with a regulated PSU .
With the one shown, considering at least 20% loss, it would be 52x.8=41.6V Pk .
You will have extra 10% loss into the emitter resistors, so this leaves you with 41.6x.9=37.5V Pk=26.5V RMS=87W RMS.
Which is also confirmed by the power transformer rating:
40VAC @ 4A= 160VA rating, good for a 100W amp, tops.
2) it does not have short circuit protection, which can be forgiven in a Home Hi Fi amplifier or even in a "fixed" installation PA (think a Church or a Theater) but never in a Musical Instrument amp which travels a lot and gets plugged/unplugged many times.
3) for that kind of power, search for the ApexAudio schematics around here, but the ones with short protection.
Rodd Elliott also has suitable amps.
EDIT: to be more precise, *one* of them has short protection, the other one does not , the Author makes tha unwarranted assumption that "if one current limits, the other is protected too" which is very dubious.
No need to bridge when you can easily get 200/8 with conventional circuits.
Hint: you'll need around 65/70V rails for that.
1) 200W/8 ohms? NO WAY
Max peak voltage on the speaker would be 52V , and that with a regulated PSU .
With the one shown, considering at least 20% loss, it would be 52x.8=41.6V Pk .
You will have extra 10% loss into the emitter resistors, so this leaves you with 41.6x.9=37.5V Pk=26.5V RMS=87W RMS.
Which is also confirmed by the power transformer rating:
40VAC @ 4A= 160VA rating, good for a 100W amp, tops.
2) it does not have short circuit protection, which can be forgiven in a Home Hi Fi amplifier or even in a "fixed" installation PA (think a Church or a Theater) but never in a Musical Instrument amp which travels a lot and gets plugged/unplugged many times.
3) for that kind of power, search for the ApexAudio schematics around here, but the ones with short protection.
Rodd Elliott also has suitable amps.
EDIT: to be more precise, *one* of them has short protection, the other one does not
, the Author makes tha unwarranted assumption that "if one current limits, the other is protected too" which is very dubious.No need to bridge when you can easily get 200/8 with conventional circuits.
Hint: you'll need around 65/70V rails for that.
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JMFahey thank you for everything!
My choice is made and I opted for the latter scheme. I drew my circuit and it remains only controlling me if the design is ok. For information the output will be darlingtons TIP142 - TIP147 and small signal transistors BC546 and BC556.
In a short time I started directing the preamplifier and amplifier. If all goes well I'll post the drawings of PCBs, of course I will make a report on the sound.
Regards!
My choice is made and I opted for the latter scheme. I drew my circuit and it remains only controlling me if the design is ok. For information the output will be darlingtons TIP142 - TIP147 and small signal transistors BC546 and BC556.
In a short time I started directing the preamplifier and amplifier. If all goes well I'll post the drawings of PCBs, of course I will make a report on the sound.
Regards!
Attachments
To which project on Rodd Elliot's website are you referring to? 68, 101 or 117??
The schema in post #30.
http://www.diyaudio.com/forums/inst...i-fi-amplifier-bass-guitar-3.html#post3519335
Thanks! But I was actually curious to which project JMFahey was referring on ESP Projects Pages - DIY Audio and Electronics
I was referring not to a specific one, but in a general way, considering Rodd Elliott a good designer, with his feet firmly in the ground.
And his designs are simple and robust.
See that rather than concentrating on minute distortion levels or incredible slew rate or perfect 100KHz squarewaves (nothing against, of course) he cares more about "muscle" .... which is proper in the hot, sweaty and overdriven Music Instrument world.
I'd start by building this one
100W Guitar Amplifier (Mk II) Figure 2 ;
100W is a very popular power level , good for rehearsal and Club/Pub shows, and yet compact, light and inexpensive.
It's enough to get even (not drown, of course ) with a normal drummer, and a Guitar player using , say, a Tiny Terror, a Blues junior or a Classic 30 , just to name a few small band popular tube amps.
Or if SS, someone using a Bandit, a Valvestate 40 or 65, or one of the many 60/65W 1x12" amps (Princeton 112, Performer, Roc Pro, etc.).
Couple it to 2 x 10" woofers, maybe add a Piezo tweeter if you are into heavy slapping and you are good to go.
Or a 4 ohms 15" .
For a *louder* band, (say, your Guitar player uses a Twin, or a 50W Marshall into a 4x12" or similar and your drummer's "other job" is being a sparring for Mike Tyson) you'll need 250 to 300W.
In this case 300/500W Subwoofer Power Amplifier Fig1 is fine.
See that basically it's the exact same design as the 100W one with added "muscle".
He didn't draw a short protection here because this particular one was meant to be mounted inside a powered enclosure, but of course you can use the one from P68 .
It's only adding 4 resistors, 2 diodes, 2 small transistors, connected the same way (sensing emitter current and clamping driver base current about a certain level, around 8A).
Read all he says about dissipation, adding more transistors if used with +/- 70V and 4 ohms, heatsinking, wiring, fusing, etc.
Lots of practical advice, that's what I like abour Rodd's projects.
Not many go into "small" but important details as deburring properly the heatsinks or mica type and thickness.
Which he mentions in his:
Project 101 - High Power, High Fidelity Lateral MOSFET power amplifier
Here you trade higher cost transistors for simplicity, but that's your choice, of course.
MosFets have no second breakdown and are robust enough to be protected by simple fuses.
As of Project 117 , it was meant more as a joke, he actually calls it "insane" and does not recommend building it.
Me neither, at those power levels simple Class AB is a thermal Inferno .... literally.
No normal Bass player needs that kind of power.
I've posted pictures of some of my customers who do, but they generally buy (or have custom made) some cool preamp, and drive big commercial PA amps.
But we are talking packed Football stadiums here.
The preamp section from that one sounds quite good for bass too, I used one for a few years on hundreds of gigs.
I got to play through the 800 watt mark bass head and a david eden 4-10 cab.
Awesome bass head and for 600 bucks or around that it can not be beat.
Never had to turn it above 10 o clock position with the gain and pre set around 9 o clock positions. (active bass of mine is hot)
Awesome bass head and for 600 bucks or around that it can not be beat.
Never had to turn it above 10 o clock position with the gain and pre set around 9 o clock positions. (active bass of mine is hot)
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