Self build Amps

Discussion in 'Ampage Area' started by MickeyB, May 15, 2019.

  1. EC Strat

    EC Strat Electromatic

    Jan 11, 2019
    676C15B1-609E-485E-AE34-3847D868903C.jpeg Here is my Tweed Vibrolux clone - I bought it wish I could’ve built it. But it’s SUPER awesome

    Vintage tones - RCA NOS tubes 12AX7 and 6V6
    GreatGretsch likes this.
  2. loudnlousy

    loudnlousy Friend of Fred

    Oct 18, 2015
    Hildesheim, Germany
    A very talentet friend of mine builts some impressive amps at home. Nice ciruits, nice woodwork and cosmetics.

    We had a very satisfying project that took us several years. (He was the buider and I just lend him my ears and some ideas.)
    We wanted to improve on the JTM45 formula. The amp turned out to be fantastic.
    Working on amps is totally fun.
  3. Winnie Thomas

    Winnie Thomas Gretschie

    Jun 13, 2011
    Cochise AZ
  4. markeebee

    markeebee Country Gent

    Thanks gents!

    I've got three or four amps on the bench which will have the Bent name. After that.....uh, it's complicated. My grandmother's name was Patricia, so I thought I might use the name 'Patrician'. It sounds like the sort of name a British company from the fifties might use. So I invented a little back story......

    PATRICIAN ELECTRICALS LTD was founded by Ernest Mugginton in 1964, following his dishonourable discharge from the British Navy after a series of misdemeanours that have subsequently been suppressed by Her Majesty's Foreign Office. The company designed, manufactured and marketed a range of navigation aids for shallow-water fishing vessels, and found some success within British crab catching fleet with their PLACE-O-METER direction indicator. After the well-publicised grounding of the 32 ton dredger 'Shellfish B'stard', Patrician's products were discovered to comprise little more than a pair of randomly-actuated electromagnets which caused the indicator needle of the Place-o-meter to swing around in a arbitrary fashion.

    Mugginton was forced to develop an entirely new product range, and drew his inspiration from the long hours he spent frequenting the Beatnik trad jazz bars of the South Coast. After much development effort (reputedly as much as an hour!), Mugginton unveiled his designs for THE CLARIFONE and THE BANJONETTE, which were rudimentary pickups and associated amplifiers for use with wind and plucked string instruments. Unfortunately it transpired that the clarinet and banjo were the two instruments that people least wanted to hear amplified, so the systems were not a great success.

    Little was heard from the company for the next few years, but in the late 1960's electric guitarists in the great Beat Boom found that the Patrician amplifiers provided them with a unique and raucous tone, and demand for the devices grew steadily. Never one to miss an opportunity, in the early 1970s Mugginton produced a range of dedicated guitar amplifiers with more modern styling and updated features. These were marketed under the brand name EARL BARON, and were adopted by notable amateur bands such as THE FLUFFERS, BOB GILLOP AND HIS ARKANSAS QUADRUPLE SHOWBAND, and heavy rock outfit ROOFRACK.

    By 1980 Mugginton was in the grips of a chronic petroleum addiction and had run up significant debts following a disastrous divorce settlement with Melina Mugginton, a former Ex-Miss Bangkok and long distance canoeist. Patrician Electronics Ltd was wound up in January 1981, and it's inventory was placed in storage in a series of lock-up garages in Brighton UK. The rest is history.....

    So, you can see I have some work to do.....a dodgy maritime navigation device, a couple of 60's inspired amps, some pickups, a range of 70's inspired amps, and - best of all - getting some mates to dress up as the Arkansas Quadruple Showband for publicity pix/video.
  5. blueruins

    blueruins Country Gent

    May 28, 2013
    Savannah, GA
    Lol!!!If you haven’t, you need to pick up a book by Jack Vance...I believe you’ll find a kindred spirit:)
  6. dankas11

    dankas11 Country Gent

    Jul 6, 2014
    hey my friends amp builders and guys who understands electronics ( I don’t :) )
    I have one question. do you maybe know where to get replacement for Fender Basman blond pot: 350k ohm with a 70k tap )350ka pot with tap point) used on brown era fender amps. body 15 mm wide, mounting hole is .335"? As I have heard they are not manufactered any more and they are important for sound? Any suggestions? Tnx!
  7. hcsterg

    hcsterg Country Gent

    Feb 13, 2012
    Lionpotato and pmac11 like this.
  8. sh4rkbyt3

    sh4rkbyt3 Gretschie

    Mar 8, 2019
    Elkton, MD
    Seems like the heat could easily be remedied for a few of those amps using a few 92mm or even 80mm computer fans and likely prolong the life of the tubes as well? Just a thought. I understand the traditional part but.....improvement.
    hcsterg likes this.
  9. pmac11

    pmac11 Country Gent

    Mar 4, 2018
    Toronto, Ontario
    No, because Fender can source all of the parts in bulk, and this is a huge savings. They can then offshore the labour cost, which is another big savings.

    You might get close if you bought a kit for the amp portion, built your own cabinet, and found some usable speakers in the local online classifieds.

    Sent from my SM-T560NU using Tapatalk
    johnny g and hcsterg like this.
  10. hcsterg

    hcsterg Country Gent

    Feb 13, 2012
    Well, as far as possible, I personally design my amps to avoid using fans : the construction must offer sufficient ventilation by itself.

    Here's what I noticed with fan cooled amps (and other equipments) and deters me to use them :
    - a fan can be noisy, or end one day to be noisy : air flushing, motor noise, bearing or sleeves...
    - a fan can generates parasitic pulse interferences : being a brushless motor doesn't prevent it from that.
    - a fan can suck and bring dust in an amp : quite bad for high voltages circuits, pots, contacts...

    That said, the help of a fan may be necessary to help cooling on big amps models - like bass tube amps heads, for example (think the Ashdown BTA-400 with its 8xKT88 output stage), or because they are built to a rack format, where a forced ventilation may be compulsory to avoid heat concentration.

    Just for the occasion of that momentary "cooling fan discussion", here is a pair of mono block amps that I build in 1993, now owned by a "Hi-Fi freak" pal.

    On these - yes - I used a switchable 3 speed DC 80mm powered fan circuit : stop / slow and noiseless / fast.

    Here are the original pictures from 1993. On the second one, you can clearly see the fan at the rear of the returned chassis :


    On the 2000's pictures below, you can notice the chassis surround openings of the tube bases : these are air vents, where the cooling air flows around the tubes glass, by chimney effect, coming from the fan inlet at the back - the fan being switched on or not. I mean : the flowing air is already enough for cooling the amp adequately by itself :


    So the air crosses all the inside chassis and ends his internal cooling run by the tubes surround outlets. Of course, if the fan is on, the blown-in air helps more the chimney effect, going from right to left on the picture below :


    The low-noiseless fan speed is enough to cool the whole amp and the chassis surface around the tubes to make it cold. The resulting noise is not more than a modern laptop fan. I had to add an electric RLC filter to avoid any fan motor interferences in the audio signal.

    Without fan activated, the temperature proved to be only lightly warm after several hours of operation. I was unsure o_O, but the natural cooling effect was enough... :cool:

    That said, the output tubes are 4x 6080WA, 2x 12AU7WA and 1x12AX7WA, already totalizing a total heaters current of circa 11 amps under 6.3VAC, so a dissipation of 70W... That's why I planned this cooling system - to be safe anyway - but fan-forcing the air flow proved not compulsory, finally.

    But it's me, OK ? :D

    Last edited: May 19, 2019
  11. sh4rkbyt3

    sh4rkbyt3 Gretschie

    Mar 8, 2019
    Elkton, MD
    Thanks Hcsterg. I wonder if applying them under the tubes themselves, increasing chimney effect?
  12. hcsterg

    hcsterg Country Gent

    Feb 13, 2012
    Sorry, sharkbyt3 :oops:, would you clarify your purpose ? o_O

  13. sh4rkbyt3

    sh4rkbyt3 Gretschie

    Mar 8, 2019
    Elkton, MD
    Just wondering if a few little tweaks would make much if any difference is all.
  14. MickeyB

    MickeyB Electromatic

    Jul 24, 2017
    Birmingham England UK
    Very impressed with the quality of the builds. I commend your cooling efforts - I once owned an amp with 4x KT 88 power tubes - the cabinet smoked after an hour!
    Regarding the fan - I did wonder if it would generate electrical noise so what is the filter you used?
    hcsterg likes this.
  15. markeebee

    markeebee Country Gent

    Best way is to use a brushless DC fan (less radiated noise than an ac fan) and use an isolated power supply (i.e. don't connect the -ve of the supply to the main ground bus of the amp). Probably a good idea to stick q 100uf across the output of the power supply as extra insurance.
  16. Uncle Daddy

    Uncle Daddy Friend of Fred

    Jan 19, 2012
    Maldon UK

    Marvellous stuff. You couldn't make it up!
  17. Axis39

    Axis39 Country Gent

    Jun 2, 2008
    La Quinta, CA
    First, let me say, @hcsterg you've done some really nice work! (I also kinda like the name Bent... Kinda seems mildly subversive. That should appeal to the Rock and Roll crowd!)

    It depends on the amp, really... Building a tweed Champ? It's probably cheaper than buying a hand-wired replica. Building a high power Tweed Twin? Again, probably ahead of the game by building.

    But, if you are comparing a mass produced, PCB build, like a Twin Reverb, to a hand wired amp you built yourself? @ $1300 bucks, you might break even, but I would wager the Fender amp is cheaper. However, the Fender amp is a PCB production, a good one, mind you, but still PCB. The hand wired amp you made yourself? Well, it's got love, some education, a lot of satisfaction, a good bit of frustration, and for me a serious sense of accomplishment when I play it at gigs.

    I mean, let's be honest, I didn't start from scratch when I built/restored/re-wired my Twin. I had to pay for the amp initially. I never would have been able to afford a working HPTT. They go for stupid money, even player grade examples. I was in the right place, at the right time, when a friend was retiring and downsizing. The newest ones from Fender, the Bonamassa Signature models, go for $3500. You can buy an HPTT kit all day long for half that (or less), probably be able to source parts for 1/3 if you are careful and you don't 'charge' for your research hours.

    But, something like a Silverface Bassman 50 or a Bandmaster, any of the higher wattage Fender amps from the late 60's and 70's.. Well, they just aren't as desirable. So, building is not gonna be cheaper.
    johnny g likes this.
  18. Lionpotato

    Lionpotato Gretschie

    Oct 10, 2018
    Bought a 72 Bassman 50 for $450 and rewired to Blonde Bassman specs. Handwired in general is far more reliable than a wispy thin PCB which is what most are today. Had a PCB Peavey Delta Blues. The heater trace burned out on the PCB. A royal pain to fix. Handwired would have been super easy fix. But you have to have the knowledge. I like working on amps and have been a student. So easy decision for me.
    Axis39 likes this.
  19. hcsterg

    hcsterg Country Gent

    Feb 13, 2012
    I searched in my notes and drawings : the filter I used was a 220µF 63V cap, the low speed was obtained via a 150R 5W resistor, and the fan was powered via a 2 wires + shield cord from the DC PSU to the fan itself.

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