Blog Forums DIY Speakers and Subwoofers DIY Vintage Guitar Amplifier Build and Discussion

last updated by drdan 7 months, 1 week ago
5 voices
21 replies
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    • #15165
      123toid
      Keymaster

      Recently I built my first DIY Guitar Amplifier.  Thought I would make a section if anyone had any questions about it. 

       

      🛠️Parts Used in Building a Vintage Guitar Amplifier:

      Eminence Speaker:

      https://amzn.to/3sPEUtm or https://bit.ly/3pKH23G

      Vintage Grill Cloth: https://bit.ly/3pItdT8

      Footnote Amplifier: https://bit.ly/3zglnTW

      12V Power Supply: https://amzn.to/3HvmGkH

      Step Down: https://amzn.to/3sPzfDl

      Finish Stain: https://amzn.to/3zp1RVy

      Top Coat: https://amzn.to/3qEYp53

      Vintage Handle: https://amzn.to/3eEH9r9

      Sound Demo


    • #15166
      tvor-ceasar
      Moderator

      That old Gretsch style always was a great look. Really nice job on the build.


    • #15168
      123toid
      Keymaster

      @tvor-ceasar 

      Thank you! And you are absolutely correct! That’s the exact one that I modeled the face after. But I wanted to add the hardwood look to it as well. You have an unbelievable eye. I can’t get anything by you 😜 


    • #15173
      tvor-ceasar
      Moderator

      That basic model is one that I was looking at when I was trying to find an old style combo to design for my son and his intended. I’m not at home, but I’ve got that one downloaded for reference. Have you ever seen the ones with the twin oval speakers on a slant? I always wondered what they’d sounded like. Terry over at D-Lab recently fixed a combo cab with an oval speaker and it sounded great. 


    • #15175
      123toid
      Keymaster

      @tvor-ceasar 

      I have they look really cool.  I am really intrigued with what some guitar speaker designers choose and why.


    • #15176
      tvor-ceasar
      Moderator

      Home.

      Here’s a 1960 Gretsch 6156 Playboy:

      (looks to be your inspiration)

       

      and this is a 1960(‘s) Gretsch 6161 Electromatic Twin Tube Combo:

      This has one been on my mind for a while. I just like the twin ovals.

      If you look, most combo amps are open back. If I had some factory 6×9’s, they’d be perfect for an open back combo. You could run a full automotive amp, even a small one, with a computer power supply, and do all the tone shaping and overdrive in the preamp stages.

      Nope, never, ever thought of any of this before…. 😉 🙄 🤣 

       

      I think the only thing I would have done differently would have been to back mount the speaker with some T-nuts or even some carriage bolts, just to facilitate easy repair or replacement of the driver.


    • #15177
      imcokeman
      Participant

      @tvor-ceasar Is there anything with a driver in it that you haven’t thought through every step of making?  

      Nice amp, and 6x9s outside of car audio sounds intriguing, outside of that Gretsch amp not sure I can think of other examples.

       

       

    • #15179
      tvor-ceasar
      Moderator

      @imcokeman 

      I’ve seen some old suitcase style and hard guitar case styles that have used oval speakers, some of really oddball sizes. Apparently the English were into oval speakers back in the day, and even quite a few home sets were built with them.

      I’m always in the lookout for the unique things in life, no matter what it may be. Keeps my mind, eyes, ears, nose and mouth sharp. 


    • #15182
      tvor-ceasar
      Moderator

      @imcokeman Here’s that video of Terry (D-Lab) fixing a Valco Amplifier with twin oval speakers from a couple of weeks ago ago. Also, Brad The Guitologist has done a few of those as well. If you want to hear them, skip ahead to the 9:00 mark.


    • #15183
      123toid
      Keymaster

      I’m going to try to get an audio clip out of the amplifier later today. It might not be till late tonight though


    • #15184
      tvor-ceasar
      Moderator

      @123toid Wish we could see you dropping it off. I can only imagine it to go something like this:

      And sounding as good. 😀


    • #15185
      123toid
      Keymaster

      Sound Demo is updated in the first post. 


    • #15188
      elliottdesigns
      Participant

      @imcokeman as long as dispersion is controlled between drivers, efficiency is high enough (or power capability high enough), distortion is low enough, and the speaker suites the enclosure. Any driver (car or otherwise) can be suitable for any application with those rules applied, meaning there’s no reason 6x9s shouldn’t work. In fact, because they are designed to fit in large leaky door enclosures, I imagine they would be well suited to an open baffle arrangement as found with many guitar amplifiers.

    • #15191
      tvor-ceasar
      Moderator

      @elliottdesigns Happy New Year! Hope you had a good celebration.

      I want to give a recap of what I left on YT:

      …”What you have to remember about what the difference is between reproduction of music in the Stereo/AV situation and music creation is that they have two distinctly different roles, and their functions reflect that. As you know all too well, the function of the HiFi speakers is to attempt to recreate the total soundstage of the recorded music/soundtrack so as to make you believe you are “there”, a part of that audio experience.

      With instrument combo amps and speaker cabinets, their functions is to create the sound which will be picked up by the microphone(s) to be recorded or to be passed on to the PA system to then be reproduced for the venue being played. In this case, the speaker/driver will usually be very close mic’d, anywhere from 6-8″ to as close as just outside maximum excursion. This gets rid of many of the concerns taken into account with HiFi because they simply don’t matter. You get the actual color of the drivers and the different parts of the driver from the center of the dust cap all the way out to the edge of the cone. Plus the driver has to be able to handle the transients and distortion introduced into the signal to create that masterpiece being played.

      So, as you can see, what you are worrying about is not a big consideration in this instance, unless you intend to have them pull double duty as just plain powered speakers.

       

      In the case of a guitar amp combo, it is essential that you can push the driver through heavy distortion and it holds up over time. The best drivers I’ve seen for this usually have accordion paper surrounds. And with the mic’ing situation, it usually gets placed close enough to the cone that even limited range drivers (the Eminence is only rated up to 4.6 kHz) sound more like full range drivers because the mic is placed well within the wavelength of the upper frequencies. Actually, there’s a 8″ Dayton Woofer that seems like it would do just as good as the Eminence driver, especially in an open back situation. A little wall boundary reinforcement and the matching bass unit I posited on the video could be a real thing. 

       


    • #15193
      elliottdesigns
      Participant

      @tvor-ceasar Happy New year to you too… ah, true, however I thought distortion with guitars is best created in the signal chain because that way it’s controlled distortion, I suppose what you are saying is that it isn’t critical. In which case, car audio drivers along with PA drivers are probably the best aren’t they? Car audio are mostly designed for handling being overdriven because this is what typically happens to those speakers in a typical build (at least I imagine so). I also imagine most people doing these builds won’t be using this amplifier on stage (MICed up), so the properties I discussed may be more important than they otherwise would. Overall though, I agree with your statement 🙂👍

    • #15200
      tvor-ceasar
      Moderator

      @elliottdesigns A lot of the distortion comes from the amp, but the way the driver reacts to that distortion is what gives the Combo/Cab it’s signature sound when really driven.

      I agree that Automotive drivers have potential, but many of them are meant to handle very high power levels and withstand the distortion at those SPL and cabin pressure levels. Good for SQ and SPL situations, but not necessarily for creating that “crunch” so many electric guitarists want (“I NEED THAT!!!” LOL).

      Take, for example, the Celestion Vintage 30. This is the most used guitar speaker of the last 20-30 years. It’s only 60 watts, and for a 12″, it’s more of a mid-bass unit rather than a woofer. If you look at its specs, other than its SPL rating, you’d pass it up for something much more suitable for hifi use. But it’s in the way it’s constructed, matched to amplifier power and the SPL level that makes it so well suited for music creation. Plus, they are tough. It takes a lot to destroy one of them, even when abused.


    • #15202
      elliottdesigns
      Participant

      @tvor-ceasar aha, I see. You clearly know a lot more about this topic than I, the only instrument I play is MIDI piano, and for that you want ideal speakers as you would for home/home theatre use, hence my assumptions.

    • #15215
      drdan
      Participant
      Posted by: @tvor-ceasar

      That basic model is one that I was looking at when I was trying to find an old style combo to design for my son and his intended. I’m not at home, but I’ve got that one downloaded for reference. Have you ever seen the ones with the twin oval speakers on a slant? I always wondered what they’d sounded like. Terry over at D-Lab recently fixed a combo cab with an oval speaker and it sounded great. 

      I have used Terry’s 6K6 PCB and think this amp would be a good candidate for that design.

    • #15216
      tvor-ceasar
      Moderator

      @drdan Did you use just the board from Terry or did you also get parts from him?

      That kit does make a really nice practice amp.


    • #15217
      imcokeman
      Participant

      interesting, I was definitely thinking more of signal chain including pedals/amp for the overdrive crunch than the actual driver being over driven, but then that last bit can only happen at loud volumes and I think even some tube amps have a lower volume setting where they can still get distortion from the amp side even without pedals.  There is a long history and I wouldn’t be surprised if the newer modeling amps takes some inspiration from all different areas that could add tone.

    • #15218
      tvor-ceasar
      Moderator

      @imcokeman

      The signal chain does most of the heavy lifting, but in the end (when you are going final analog, aka the speaker and mic), it’s how the driver handles the signal. For example, the kit Dan built from Terry (D-Lab) is pretty much a 3 watt amp, but you can overdrive it and get that lovely tube distortion. If you try different drivers with different constructions and materials, you’ll get different final sounds and tones, some of which you’d expect, but some are actually due to the way the cone and suspensions react, staying stiff enough to react quickly, yet flex enough to enhance that distortion to give it what you are looking for. 

      Sometimes I find it hard to really express how it works because I see it in my mind how the signal comes out of the amp, with all it’s desired “enhancements”, going into the voice coil, moving up through the cone and being constrained by the surround and spider, and seeing the initial stiffness around the voice coil former/dust cap and how it weakens out by the surround, and how the particular material introduces its own bits of distortion the further out you go, I wish I could share my mind’s actual view. Until I can, I’ll continue to attempt to adequately share.


    • #15221
      drdan
      Participant
      Posted by: @tvor-ceasar

      @drdan Did you use just the board from Terry or did you also get parts from him?

      That kit does make a really nice practice amp.

      I had the parts already and soldered my own, but Terry offers a populated board. You also need two tubes, two pots, as well as a power transformer and output transformer. I also had all of these things, along with chassis parts, from other projects. His drawing shows you exactly how things are hooked to the board. 

       

       

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