dave251 Posted March 24, 2002 Share Posted March 24, 2002 Here's a photo of the amp I've been wanting to build for some time now. This is a pure class A design, based on the Western Electric 300B output tube. My amp partner got it put together last night. He still has some issues to work out, but we hold high hopes for the design. There is no tone stack on the amp. As it is designed to enhance the sensitivity of the Wendler electroCoustic guitar, we felt that there just wasn't any need. We may at some later date. The design goal is to make the guitar/amp a system, ie, to function as one unit. Using a simple three tube, "0" negative feedback design, we hope to achieve the utmost in sensitvity between the player and the loudspeaker. In all of our research, this design looked to be the most simple and best sounding(a hi-fi approach)...there are only 24 electronic components in the amp!! While output will only be in the range of about 10 watts, we use a JBL speaker to enhance the loudness. I've been playing with an E130(15" lead speaker) for the last month...and it gets loud in a hurry, while still offering a wide frequency response. Once we get it tweaked in, I'll try to get some MP3's done.... http://images.prosperpoint.com/2139/107992-10.jpg Dave Wendler Instruments Link to comment Share on other sites More sharing options...
Binky_dup1 Posted March 25, 2002 Share Posted March 25, 2002 Interesting. Look forward to the MP3's. Bet toy're really lookin forward to firing it up. http://www.plaudersmilies.de/devil/sasmokin.gif Link to comment Share on other sites More sharing options...
myles_rose Posted March 25, 2002 Share Posted March 25, 2002 Originally posted by dave251: Here's a photo of the amp I've been wanting to build for some time now. This is a pure class A design, based on the Western Electric 300B .... I've been playing with an E130(15" lead speaker) for the last month...and it gets loud in a hurry, while still offering a wide frequency response. Once we get it tweaked in, I'll try to get some MP3's done.... Dave, We have talked on this project a bit, and I have to say, you are doing a fantistic job! I was on the phone late last week with Andy Marshall at THD, and we were talking about your amp. He thinks you have a great idea too. It will be interesting to see what sort of power range and voltages you come up with, as the 300B is used in a lot of less than 5 watt amps, but is quite capable of running up to 40 watts, depending on voltages. I guess the factors here would be how much you want to spend on transformers and how heavy you'd want the amp to be with the transformers at those sort of higher wattages. I think this amp, even at 10 watts, which is a lot different in Class A watts, so to speak, than class A/B watts, with an efficient speaker, would make most 100 watt stacks seem tame! Again, I am very impressed with your work, and be sure to keep me in the loop. I'd be one of your first customers! On the 300B .... the Western Electrics are very pricy, but Svetlana and JJ have offerings. The Western Electric is about the only one that I think would handle the voltages and requirements for a higher powered amp, but for under 20 watts, I think you have a pretty open choice. Maybe drop me another email and let me know what 300B you are planning to use. Regards, Myles Myles S. Rose www.guitaramplifierblueprinting.com www.la-economy.blogspot.com www.facebook.com/mylesr www.twitter.com/myles111us Link to comment Share on other sites More sharing options...
dave251 Posted March 25, 2002 Author Share Posted March 25, 2002 I believe this one is the Electro-Harmonix(I haven't actually seen the amp yet, it's in KC)...they also offer a Sovtek at about half. Western Electric(Westex)are WAY too high. Even with what we are using here, this is going to be a $2000 amp, including the E130. There will be a guitar priced similarly, for a total package of $4-4.5K. While to the unitiated this sounds a bit pricey, it's nothing for a quality acoustic to get into the $5K range. Thank god the circuit is simple... I can't start getting a good mark on the components until I hit about 35 units(on the JBL speakers mostly); If I can sell that many, it's going to be worth our while. As I said, we have some tweaking to do but I have confidence my partner will be able to work it out. http://images.prosperpoint.com/2139/107992-12.jpg I share this with the "world" because I believe it's time has come...an electric instrument that has the tonal nuance and touch sensitivity of a good acoustic. And I further believe to achieve our goal, it has to be as simple as it can be.... Dave Wendler Instruments Link to comment Share on other sites More sharing options...
Gabriel E. Posted March 25, 2002 Share Posted March 25, 2002 Very nice! I love the single knob. "You never can vouch for your own consciousness." - Norman Mailer Link to comment Share on other sites More sharing options...
myles_rose Posted March 25, 2002 Share Posted March 25, 2002 Originally posted by dave251: I believe this one is the Electro-Harmonix(I haven't actually seen the amp yet, it's in KC)...they also offer a Sovtek at about half. Western Electric(Westex)are WAY too high. Even with what we are using here, this is going to be a $2000 amp, including the E130. There will be a guitar priced similarly, for a total package of $4-4.5K. While to the unitiated this sounds a bit pricey, it's nothing for a quality acoustic to get into the $5K range. Thank god the circuit is simple... I can't start getting a good mark on the components until I hit about 35 units(on the JBL speakers mostly); If I can sell that many, it's going to be worth our while. As I said, we have some tweaking to do but I have confidence my partner will be able to work it out. I share this with the "world" because I believe it's time has come...an electric instrument that has the tonal nuance and touch sensitivity of a good acoustic. And I further believe to achieve our goal, it has to be as simple as it can be....Dave, Not to cut my own throat .... but $2000 is the projected price for the amp? Have you looked at the cost of other "limited production" amps, even those such as Matchless and Victoria? I am a bit in touch with the cost of components, and the cost of your transformers and the 300B itself, are very high. I recognize your caps from the photo, and your sockets, and there are sockets available for 1/5 the cost, and your caps are very expensive. At least two of your high wattage precision resistors are very pricy too, and the workmanship ois first rate. The excellent Univalve by THD is $1000, and a bargain at that price. Their new BiValve 30 is about $1500 I believe. Now on top of this you will include a JBL speaker? Perhaps your $2000 is dealer cost with a 40% mark up expected for retail or something, I may be a bit lost here. In any case, I was asking to be among the first on when the amp is in production, but to reconsider, I would like to be put at the top of the list if there is nobody there yet. Knowing the costs of some of the parts here, looking at your work, and seeing some of the way you build guitars, I am just hoping your guitars will support the business long enough for you to produce the amp, and get one in my hands .... before you realize that an amp like yours in the high end audio world goes for about three times the cost at least. Check some hi end audio sites for 300B class A amps, with the same tube compliment but less in the way of pots and EQ, as that is all in the $7500 preamp that you need too. I am an electric player as you know, but use my Univalve more than any other of my amps at this time. I'd love to play an ES-175 or L5 with your amp, and you know, I am even starting to play some of my acoustics more often and am thinking of yours more than I'd care to admit to my wife. Keep me in the loop! Regards, Myles Myles S. Rose www.guitaramplifierblueprinting.com www.la-economy.blogspot.com www.facebook.com/mylesr www.twitter.com/myles111us Link to comment Share on other sites More sharing options...
Dak Lander Posted March 25, 2002 Share Posted March 25, 2002 Dave, that's one heck of a nice looking amp setup. As I told you before, I'm lookin hard at one of your guitars because of the sound demo cd you sent me. If this amp helps that, even a little bit, you can count me in on one pretty close behind Myles. Also, I'll be in touch before too long and order that pickup you suggested. The Guild definately needs something other than the Fishman I have in it now. Our Joint "When you come slam bang up against trouble, it never looks half as bad if you face up to it." The Duke... Link to comment Share on other sites More sharing options...
dave251 Posted March 29, 2002 Author Share Posted March 29, 2002 Made a couple of minor changes....we weren't getting enough gain from the 6SN7, changed to a 6SL7. Also, I was wondering if we really needed that tube rectifier....would a SS really make a tonal difference in a pure class A amp? Dave Wendler Instruments Link to comment Share on other sites More sharing options...
myles_rose Posted March 30, 2002 Share Posted March 30, 2002 Originally posted by dave251: Made a couple of minor changes....we weren't getting enough gain from the 6SN7, changed to a 6SL7. Also, I was wondering if we really needed that tube rectifier....would a SS really make a tonal difference in a pure class A amp?Dave .... A few suggestions .... First, on the "six series" preamp tubes, unless there is some specific reason for these, I'd forget them for a few reasons: 1. They are not all that easy to find, as far as good ones. 2. They have a higher percentage of being microphonic than a 12AX7 config. If you want to wire the circuit for one, you can always also include a little device called something like "subssitube" which is available from Groove Tubes, which will allow folks to use either the 8 or 9 pin configuration. This also allows one to easier change gain structure by using a 12AX7, AT7, AU7, AY7, 5751, ECC83, 7025, etc. Next ... as far as a vacuum tube rectifier, in a single ended class A amp, these are not the best idea. In something like a class A Matchless or Vox, they are fine, as when you start to drive the amp, the tubes are really working in a puch-pull config, even though cathode biased. But .... single ended class A amps are a different story. Most folks think that class A amps conduct all the time at the same level, whether at idle or full output. This is "somewhat" true. In reality, at idle, the tube is conducting 100% full current draw, but as signal is applied, this actually drops a little bit, maybe to 95%. So, with a vacuum tube rectifier, the exact opposite happens than in a push-pull or class A/B amp, that is, as the voltage builds, you actually have a drop in volume rather than a rise, sort of an opposite compression thing going on. In conventional music such as a recording in a Hi Fi environment, the sound is more constant, even in pieces with a wide dynamic range such as symphony music, so vacuum tube rectification is fine. In a guitar amp though, and for what you are doing with acoustic instruments, a solid state rectifier would be more accurate and articulate. You would also need less from your power supply, and you would not have to wire in the rectifier socket, or if you wanted to, leave it and supply a solid state plug in rectifier, and if people wanted the tube rectifier for the "look" or to be trendy, then they could just plug one into the socket. You're doing great, keep it up, and I still want one, even if I have to make those changes myself, as they are pretty fast and easy to do. Regards, Myles S. Rose www.guitaramplifierblueprinting.com www.la-economy.blogspot.com www.facebook.com/mylesr www.twitter.com/myles111us Link to comment Share on other sites More sharing options...
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