| Archive for harpmicforum.myfastforum.org A discussion on amplified harmonica. Post you questions/comments about mics, harps, amps, tubes, music. Drop by my site, http://www.harpmicgaskets.com. |
| isaac |
"Solid State Tubelike" mic preamp for harp-- YouTuHi All,I built this "Solid State Tube Sounding" preamp from a schematic found here: http://members.tripod.com/gillcar/id24.htm I posted a video on you-tube of me playing through it to my Pignose with a couple of different effects, and one of my own custom low-z dynamic mics. You can check it out via the following link: http://www.youtube.com/watch?v=zVD97PAx4qc I'd really like to hear your feed-back as to how it sounds. Although I *basically* know what a tube amp is supposed to sound like, I have never actually owned one myself, so I am not sure how close this preamp gets. I do think that it sounds really good, and definately sounds *better* to my ears than a standard solid state preamp... Certainly more smooth than just the Pignose on it's own. Now, the question of it sounding "tubey"? Well, I'll let you decide! (PS. I will soon post another video to my YouTube channel of the preamp into a 20w PA amp, and compare that sound with the same mic plugged directly into the PA amp's built in mic preamp.) |
| gheumann |
I listened. Very, very hard to tell from a recording like that - partly due to the crappy speakers I have on my computer. But here are some things I know to be true:
1) The guitar amp makers have been trying to get a warm tube amp sound from a solid state amp for years. My guitar playin' buddies tell me that some of the best of those, which cost upwards of $4K, are getting pretty good.... but aren't all the way there yet.... for guitar. 2) Harmonica is even harder than guitar. Why? Because we send a more distorted signal INTO the amp. 3) When a tube is overdriven - literally asked to amplify more than it is capable of, the result is analog distortion made up of many harmonics but all blended together. The degradation/distortion is analog too. When a transistor is over-driven, it simply goes square-wave. (The output rises to the device's max, then stays right there over time as the input signal continues to rise, reach its peak, and then fall again until the input signal's amplitude falls low enough that the amplified signal can again amplify it accurately.) This clipping when viewed on an oscilloscope shows very sharp voltage transitions, triangular and square wave shapes with very sharp corners. The result is harsh sound. Now - I'm not an electronics expert, and I can't tell you much about the circuit you're playing with. I also know that wiring stuff together and making it work is fun - reason enough to do it no matter what. I commend you for even trying. I don't know whether your goal is simply self-education, great harp tone, or some commercial hope - but in any case I think what you really need to do if you want an honest answer to your questions is to get some perspective. You need to hear what a good, all-tube design sounds like, first hand. (warning: not all tube amps sound good for harp!) Where do you live? If there's someone on this board near you (including me) I'm willing to bet they'd be happy to give you a demo and/or let you blow through one of their amps. If you want to hear what "great tone" is - find some harmonica players whose tone you really like and see what they're using! Know, of course, that merely using what they use won't make you sound like them - good harp tone comes from a great deal of technique - great acoustic tone to begin with and a lot of experience with mic cupping technique. But once you hear what YOU sound like through that equipment, you'll have a much better idea of how your electronics compare. I would also point out there is no rule that says your tone has to sound like great tube tone. Lots of harp players experiment with lots of effects, amps, boxes, etc - and come up with a "signature" tone that THEY LIKE and that is recognizable - and may or may not bear ANY resemblance to a warm tube sound. Finally - in the future, if you make more videos like that, we'll have an easier time giving you constructive feedback if you eliminate as many variables as possible. I'd prefer to have heard just you, your mic and your amp - with and without the preamp, and nothing else in the chain. |
| isaac |
Hi Greg,
Thanks for your great reply! Yeah, I do realize that in I should have just done a simple head to head comparison of the sound of my amp with and without the SSTS preamp... That's definately next on the agenda for my YouTube channel. My main goal with this stuff certainly isn't commercial.I'm basically an intermediate player, who has done it all on my own so far... Playing around with audio circuits (and mic building) has basically become a second hobby of mine that I mainly enjoy because the results of it are things that I can actually use in my number one past-time: playing Harp! I've done a lot of research (albeit, all on the internet) on audio circuit theory, build methods, and schemtatics, and I've really enjoyed learning what I've learned so far. But, as you probably know, the internet can be very sterile and sorta lonely, so I've recently taken to using YouTube and forums like this one try to regain some of the interpersonal communication that I've found missing... I like the idea of getting feedback from others on the results of my hobby because I'd like to know if I've stumbled upon something that other people like and can use. Then I'd be really happy to know that I've been able to share it with people who appreciate it. This particular device is one of several tube emulating designs I am building... It just happened to be the first I got to work correctly!  My mission is NOT to build an accurate solid state replacement of a tube amp (of a specific tube amp, or even of tube amps in general)... I'm aware that the "tone" of tube distortion is due to the difference between the way they distort and how transistors distort. I've come across various sources that indicate FET (both JFET and MOSFET) transistors have properties that, if exploited by the proper circuit, can largely avoid that square wave problem. I have seen the evidence that these circuits can produce distortion with even-order harmonics, and have heard clips that also prove this aurally. One source of this info is from the website I refered to in my first post, and another major source has been www.runoffgroove.com
I'm basically am looking to build really nice sounding solid state preamps that provide various tonal qualities that sound good with amplified harp... I'd like to be able to really understand WHY these device have the tonal qualities they do, and HOW they obtain them. There's no way I could ever afford to buy someone elses' boutique harp amps and effects, anyway, let alone be able to buy enough of 'em to make an educated decision about tone. My only recourse is to build stuff myself, and luckily enough for me, I really enjoy doing this stuff... I also believe in the DIY ethic and of free knowledge and sharing, and that if you don't at least TRY to do it your self, then you'll never really know what's going on... As for your question about where I live: I currently live in Tempe, AZ, where I am a poor grad student at ASU... I've looked pretty hard, but I really haven't found a community of people here interested in blues harp or even really in the blues in general... I've got a couple friends that are into DIY amps and effects, but they're all rocker types who play guitar, and have no room for the harp in their musical repertoires... If anyone on this list lives nearby, I'd be very happy to meet up with them to do just as you suggest!!! By the way, before coming out here for school, I used to live in San Mateo... I gather from your website, that you live close by there, and I've noticed on Harp-L that there seems to be a really nice (and fairly large) community of blues harp players and teachers back in the lovely old Bay Area... It's too bad I didn't realize that when I still lived there... Would be really nice to get a chance to actually talk to like minded people about the harp... I feel I'm basically at the point where I could really benefit from some sort of community, but there really doesn't seem to be anything here like that. It's high on the list of things I don't really like about Arizona, and just another reason why I'm leaving this state just as soon as I get that ol' Dissertation done! And as time goes by, I miss the Bay Area more and more! But anyway, thanks again for your great reply... I really appreciate your advice! |
| isaac |
I forgot to also mention Holmes Engineering as another inspiration source. All the harp commander products are FET-based circuits. I'm not trying to build myself anything so complicated as what those devices do (and I understand they do what they do VERY well), but I'm heading down the same garden path as they. Ron Holmes believes in discreet FET circuitry for harp audio (check out his free book on the subject: "Harp Player's Questions and Ron's Answers" <http://www.lulu.com/content/1143681> )
FYI, my next project will be a single FET, low-gain, preamp/buffer designed around the runoff groove "fetzer valve" design. I'll use the "fender' type dual inputs--one high and one low impedance--but make sure that those impedances are correct for harp mics. What I mean is that i will adjust the circuit to have one input that has a load of ~5 M Ohms, and one with a load closer to ~150-200 Ohms... Check out the Fetzer Valve circuit at: http://www.runoffgroove.com/fetzervalve.html I'm really hopeful for this circuit... It seems like it could be a really nice one for use with harp, and very versatile too... Cheers, Isaac |
| Jeffrey Spoor |
Shoot, why not build a little harp preamp with a 12ay tube! Sounds like you have the skills. |
| isaac |
Solid State Tube Sounding preamp, round 2!!!Hi all... I have now uploaded a video of a head to head of this preamp, both set to a clean and to a dirty tone, with the built in preamp in my PA... There is nothing at all in my effects line. It's just harp (Bb Blues Harp), mic (simple lo-Z dynamic element), preamp (either the SSTS pre, or the PA pre), PA. Nothin' else! Take a look at this one, I really think people will hear what this thing is capable of...http://www.youtube.com/watch?v=f6OcNZjEu0U If you like it, let me know! Cheers, Isaac |