I was going to hijack the harp Attack thread with this, but I thought I ought to just start a new one, so here goes:
I love hearing people say good things about pedals like the harp attack, harp commander, etc. Why? They are 100% SOLID STATE! I'm a transistor heretic myself, and I just love to hear tube purists rave about circuits that don't have any tubes in them. The facts are just this: a cicuit that is well designed and voiced for harp will sound really good regardless of the components. Why is the conventional wisdom that you need tubes to sound good? Well, one is tradition (all amps in the 40's/50's were tube amps), and another is that since nowadays tubes themselves are very expensive, no one bothers to make a crappy tube amp. Transistors are between 10 cents and a dollar a pop, so soild state amps CAN be made cheaply. The use of IC's make solid state designs even cheaper, so there is little impetus to make really nicely designed, properly voiced solid state designs. The Harp Attack is a new exception to this, but so are many of the classic "overdrive" pedals (tube screamer, blues breaker, etc.). Anyway, I started out with solid state because it was cheaper for a novice like me to get into, and less dangerous (no high voltage), but now that I've heard a lot of tube amps and better understand what sounds good with harp, I'm even more convinced that really it's the design of the circuit, and not the the components (obviously quality components are important) that count. It's important to note this: You CAN make a transistor sound GOOD, but you CAN'T make it "sound like a tube". I've moved beyond the idea that solid state designs need to sound like tubes to sound good. I've realized that solid state designs, like any design, just need to sound good. Period.
Anyway, when I'm done with it, I'll make a video of a new preamp I'm making, and you can see what I mean. I took a circuit that was a nice mild overdrive for use with guitar, and reworked it to sound good with harp. i've had it on the breadboard for a month,and I've experimented extensively with component values, and I've finally got a combination I think sounds good...
Isaac, One minor correction the Harp Attack has a mini 6V6 tube in it. So is not strictly Solid State. The Harp Break is however Solid State.
But you make a good point. Solid State can sound good for harp. It's just that generally tube amps give a warmer smoother sound with is rich in overtones when driven reasonably hard. Solid State tends to have a harder edge to it which is not as pleasing to a lot of players.
At home I use a 7-100 Pignose for amped practice and love the tone it gives. But for live situations I usually prefer the warmth of a tube amp (HarpGear Double Trouble).
Having said that though, I gigged for a number of years using only a Boss GE7 direct into a PA in conjunction with a JT30 (MC151 crystal element) and it was a decent enough sound and of course highly portable.
At the end of the day though it always comes down to the player. If you have a good acoustic tone you will sound good through any gear whether tube or Solid State. The opposite applies as well of course. If you have lousy tone then no gear in the world will make you sound great.
Some of the new solid state amps took the lead from GK, who several years ago, began making solid state amps using something that was borrowed from tube amp technology, and that was using an output transformer in the amp so that instead of distorting the odd numbered harmonic overtones, which tend to sound harsh, like a tube amp, with the output transformer, it would then distort the even numbered harmonic overtones, which tends to sound warm and pleasing to the human ear. The early solid state amps were not too great for harp, but the technology sure has changed and this comes from a diehard tube amp guy.
Kingley's last paragraph is the absolute, undeniable truth!!!
OOOOOHHHH Isaac - you rebel - I'm really interested in how your preamp turns out - I've been studying this stuff lately - on the down side, I should be woodshedding instead!!!
Hey BBQ - good to see you over here as well!! ;-) Is there no place I can hide from you???;-) ---------- If it ain't got harp - it ain't really blues!!!!
Ahh, Yeah, I was thinking of the Harp Break... Harp Attack does have a tube in it. Harp Break uses diode clipping. Also, you can set up the overtones/harmonics anyway you want by using clever circuitry. If you want odd harmonics, you set up an asymmetric clipping arrangement where diodes clip more on one side of the signal than the other. If you want soft clipping, you set the clipping threshold of a gain stage appropriately for a given signal level coming from the previous stage. You also select a device with a softer Knee (FET vs BJT transistor, or germanium diode versus silicon, etc.). Most importantly, you play around with the frequency response at EVERY stage in the circuit. This means fiddling with R/C network values to attenuate some frequencies and accentuate others. You do this between every gain and clipping stage, figuring out the best values for the sound you are after. Some arrangements of of gain/clipping stages need an overly bright input in order to get the nice warm sound out the other end, or else they sound muddy. Other stages will need to have the treble cut or else they sound too tinny. This is of course much easier to do when you keep the number of stages low. So far, my best results have been with two stages. after that, it's hard to keep track of the effects of one component change all the way down through the line of signal modification. This is not to say that two gain stages is some magical number. All I'm saying is that you will prob need fancier equipment than what I have (a multimeter and my ears), and more engineering knowledge than I have to be able to easily and successfully design a good sounding circuit with more then two or three signal-modifying gain stages. I'd say that this is true for both tube and SS designing. The one thing about SS designs that make them very attractive is that you can afford to buy LOT'S of differnt components,a nd then fool around with them. It's easy and very cheap to switch out different transistors. It's the same concept as doing tube swaps, but you don't need to drop $15-20 just to put in a lower gain FET. Also, your working at 9-12 volts for most SS preamp circuits, so you don't have to worry about getting zapped, and you can use a cheap battery power source and not have to pay for all that heavy Iron in the high voltage transformers. When you want to build a SS power amp, you just get a chipamp kit for $10-50, slap on a power supply and transformer (another $10-15), attach your preamp (with a voltage regulator chip to step the voltage down to 9v) down and your good to go. ---------- ------------------ The magnificent YouTube channel of the internet user known as "isaacullah"
Last Edited by on Oct 28, 2009 2:51 PM
You need an oscillascope isaacullah so you can see the waveforms you're playing with. I had one but blew some of the diodes in it and it was too costly to repair. It was a lovely bit of kit though and extremely good for circuit experimentation purposes. Wonder if it would be possible.... no, just thinking aloud but it would be nice to be able to download a simple one to use with a computer?
Tooka, that certainly got me thinking (and googling). $139 is still way to rich for my blood, though. Here's a completely free piece of software that might do the trick: http://www.sonicvisualiser.org/
It's open source, and developed at a university. It's not an oscilloscope per se, but it seems like it'll do the job in a pinch. I imagine using it this way: Play a reference tone through the circuit, and record the output of the circuit to your PC. Then use this piece of software to analyze the waveform, and compare it to the true reference tone. My tuner will put out reference pitches through a 1/4 out jack, so that could be a good source of a steady signal. Also, I think there's free squarewave generator software out there too... hmmm... I think I'll give this a try actually... I'll let you know what happens...
I just love it when you eggheads talk dirty like this-- blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, tubes--blah, blah, blah, blah, blah, blah, blah, transistors.
I think I'll just keep playing acoustic. . .;-)
Last Edited by on Oct 28, 2009 9:05 PM
Wow, I'd never have thought of a software oscilloscope! Obviously you'd need some kind of interface to protect your PC from high voltages.
If I were building a solid-state amp, I don't know if I'd want to include any integrated circuits. Maybe operational amplifiers. In fact, I wonder if operational amplifiers could more or less replace transistors? It would be fun to experiment with that to see if you could employ the negative feedback to emulate valve/tube compression.
The problem comes when you want to convert from voltage amplification to power amplification - I wouldn't know where to begin.
I was last interested in this kind of thing 30 years ago, and I see from Wiki that Op Amps are probably used more than transistors nowadays. In 1979 the 741 was only 11 years old, so it was state of the art! http://en.wikipedia.org/wiki/Operational_amplifier 1968: Release of the ?A741 – would be seen as a nearly ubiquitous chip
Now I wouldn't even know where to buy one. I guess you can buy a bag of 100 for £20 on the internet somewhere.
Wiki warns that the basic 741 is nowadays considered to be too noisy, but if all you're doing is emulating tube amps, who cares?
Here's one source. I wonder if I'd be crazy to get interested in this shit again! http://www.rapidonline.com/Electronic-Components/Integrated-Circuits/Operational-Amplifiers/Operational-amplifiers/67379/kw/82-0334?source=googleps&utm_source=googleps
Last Edited by on Oct 28, 2009 10:41 PM
I've been playing at mic nights with a little crate 15W solid state amp that was given to me. It sounds like crap on its own, but when they mic it and put reverb on it, it sounds pretty good. Every time I play people ask, "man, what amp is that?" I show them, tell them "I'm wanting to get a good tube amp." They say "dude, THAT amp sounds great." I think the speaker is 6".
The only drawback is if I play someplace else, where they don't mic the amp into the pa, I have really crank it up, and the high notes are just too piercing. So, I turned the eq's high range all the way down, now it's not so bad.
@Andrew@ You've thrown me now. You said you were into this kind of stuff 30 yrs ago. From your previous posts I had you down as a twenty something student doing maths. How did I go wrong? ----------
I'm 49. 30 years ago I studied electronics at university, but hated it and wished I was studying maths. Now I'm studying maths I'm hating it and don't know why I'm bothering!
Last Edited by on Oct 29, 2009 5:32 AM
@Isaaculla I like what I've heard you say about "good" design. I wish I had the time to do the same thing you have been doing. I want to ask a question about my pet theory about amp design.
My opinion has always been that the tube sound people like the most is from the Class B push pull amp through a transformer. The energy in the transformers magnetic field soften and round out the harsh wave forms when the amp clips, and the push pull make for symetrical wave forms that produce the pleasing even order harmonics. The question.... have you done solid state push pull via a transformer. I've heard solid state, I've heard transformers, I've heard 6V6, (a low power 6L6). I'm all for class A amplification in the preamp,but I believe in class B in the output. What's your experience??
@ Jim: I personally have not built a push-pull transistro amp,a dn I have not really fooled around with OT's, but I have two amps that are solid state that do this. They both sound good for harp. One is the Legendary pignose 7-100, which has an x-former between the preamp and power amp as well as an OT between poweramp and speakers, and the other is an old Realistic (radioshack) brand solid state PA amp that I modded very slightly and mounted in a cabinet with a vintage 8" speaker from an old organ to make a really bitchin' small 20 watt combo amp. In fact I just finished putting that one together the other day. The secret was to re-tap the negative feedback loop form the 8ohm output of the OT to the 4 ohm output. This lets some nice breakup happen while still reducing noise and hum. I made it switchable too, so I can get crunchy (on the 4ohm tap) or really clean (on the 16ohm tap). I'm not sure if it's class a or class ab, (I can't find a schemo for it, and I was too lazy to trace it out by hand), but it is definitely push-pull. Same I think for the pignose (for which I do have kind of crappy schemo for).
@ mr_so&so: Yeah, I've tried SPICE before, and some cad programs for drawing circuits, but the problem is that I'm not an engineer, and these things are way to complicated for a novice like me to use correctly... I've started using a nice piece of free layout software called DIY Layout Creator, and I draw schemos with MS paint and a library of electronics symbols clipart. I do most of my testing by ear and with a multimeter, but I think I'll start using that Sonic Visualizer program to analyze the sound now. It's VERY cool and very easy to use. Much like audacity, but made to analyze music rather than edit it. Actually anyone interested in really understanding a song shold give it atry. It'll figure out measures, beats, time signature, song key, notes, etc. as well as letting yo make statistical comparisons between tracks, and stuff. Pretty cool stuff. I know a lot of peopl over at the DIY stompbox forum use spice to simulate their circuits first. Some swea by it, and others say that there is no way to tell how a circuit will sound until you listen to it in real life... I don't don't necessarily support one camp over the other, but I guess I fall by default in the "listen and learn" camp because of my education limitations! Thanks for the comments! ---------- ------------------ The magnificent YouTube channel of the internet user known as "isaacullah"
Isaac - talking about "solid state" have you heard much discussion about the ToneCore DSP Developer Kit? It looks interesting, but probably has a really steep learning curve. I sort of want one for Christmas now ;-)
Keith, Yeah I've seen that ToneCore kit. It looks very cool, but at ~200 bucks, it's again too rich for me. In terms of DIY dsp, something that I WILL be getting is this: http://www.oct-distribution.com/. It's a pre-programed module that lets you buid a super awesome multi-reverb-delay-tremolo-chorus-awesomeness pedal or insert as an on-board fx unit in your amp. All for $25 and some switches. ---------- ------------------ The magnificent YouTube channel of the internet user known as "isaacullah"
Okay, here's a video of that Realistic brand, model MPA-20 PA amp that I modified and made into a combo amp (see above). I don't have the preamp soldered completely yet, so that will have to come next week. I'll post another video in a new thread about those footdrums I'm using.
Hey Isaac - is this thing you're working on going to be something like the Harp Attack or like an add on to your amp? It sounds interesting - leave those drums alone and get it finished I want to hear it!! ;-) ---------- If it ain't got harp - it ain't really blues!!!!
jawbone. The beauty of working with chipamps is that they don't NEED a preamp section--the chip can take direct input from a low level signal and make very loud. The preamp section you put in a chipamp is there ONLY to shape the tone. that means that you can use ANY distortion/overdrive/DI design and use it as preamp in a chipamp. So, this is a long way of saying that the thing I'm working on will be for using inside an amp I'm building, but that it COULD be used as a stand alone pedal/DI like the Harp Atack. All you would have to do so is to put it in it's own box with a 9v battery powersource with an on/off switch, hook up 1/4" jacks at each end, and optionally some sort of bypass switching if you want to use it like an FX pedal. You could use it to go straight to the PA, or you could use it to overdrive your amp directly.
Yeah, I'll get it together soon. Prob by next week. I'm still a bit busy with school stuff, but I'm trying to give myself a little "harp 'n electronics" time each week so I don't go completely insane! I'll make a vid, and I'll post the schematic too... ---------- ------------------ The magnificent YouTube channel of the internet user known as "isaacullah"
Man, this stuff is so far over my head...should I put off getting the Harp Attack? I've been studying up on simple preamps and such but haven't tackled anything yet - to heck with school, get this thing done and then sell me a schematic!!!! Get off the forum - back to work!!!!
---------- If it ain't got harp - it ain't really blues!!!!
