A big THANK YOU to Paul Marconi for taping these and posting them! There's about 40 minutes of video here. Needs to be edited down but there's a lot of good information for anyone interested in the intersection of harmonica and amplifiers.
Video 1:
Amps - feedback and where it comes from. Gain, Power, Volume, Tube substitution.
Video 2: wrap up on amps and speakers - then on to mics - mic'ing amps, stick mics, bullet mics, demonstration of Audix Fireball, Ultimate 58, Ultimate 57, bullet mics. Microphone elements. Shure elements, their names and evolution. Compression.
Unfortunately the video runs out before the final discussion about tone. If anyone at HCH has video of that- please let us know!
Thanks Greg for sharing these vids. I was at the HCH discussion and its sure nice to recap. I'm not a tech guy by any means. I heard and read about a lot of the info provided, but sure is nice to hear you guys explain.I was fortunate enough to camp next to Randy and his lovely wife Missy. They were so gracious to share so much information. ---------- And I Thank You !! KCz Backwoodz Bluz
Kinda weird, vain too, this video was posted for me. I just bought an ultimate 57 from Greg and he replaced an element in an astatic shell for me. And now my 60 Concert won't get past 3. I'm seriously pleased with it at 3 but I'll have a lot more control with changing some pre-amp tubes. I'm going with ay3's instead of au's. They're about 40% gain. This info comes by way of an old friend and harp master who committed many months to studying early Brown amps. He actually built a brown twin. Paul Linden -gigs with a Bandmaster. Tremendous piano player and I hear he's getting serious on guitar too. He worked for years with Sean Costello. Much thanks for these videos.
Last Edited by on May 30, 2012 6:11 PM
@Littoral - trust me on this - unless your amp building, piano/guitar guru is also a performing harp player, he just doesn't know what's best for you. Mics and pickups are just totally different animals. I've played three x 12AY amps and two x 12AU + 1 12AX amps. I like the latter better - it reduces gain about 3X more than the 12AYs will which will let you run the power amp section harder. You will STILL be able to get feedback long before your volume control is at 10 - so there is still plenty of gain. Tubes are relatively cheap - and 3x 12AY's may be fine for you - but I encourage you to buy a couple of 12AU's while you're at it. ---------- /Greg
@ Greg - "@Littoral - trust me on this - unless your amp building, piano/guitar guru is also a performing harp player, he just doesn't know what's best for you."
Paul Linden is a harp playing, amp building, piano/guitar guru. He has a great tone, an awesome amp collection and a great Facebook page dedicated to the brown Fenders - Fender Brownface Amplifier Appreciation Society.
Replacing AY's with AU's does more than halve the gain if we're talking series stages, as amplification factor is multiplied, not added, e.g. 44X44 = 1936 roughly for an AY, vs. 19X19 = 361 for an AU (less inherant losses in the circuit) not that it matters, what sounds right IS right, I would be wary of using a 12AU7 in the PI of a Concert though, high voltages & bigger current draw there, though the old CC plate resistors are pretty sturdy. ---------- www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by on Jun 01, 2012 1:41 AM
Tube Designation Gain Factor Can Be Substituted With - 12AU7 -19 -12AV7 12AV7 -41 -12AY7 12AY7 -45- 12AV7, 12AT7, 5751 12AT7 -60 -12AY7, 5751 5751- 70- 12AY7, 12AT7, 12AX7 12AX7 -100- 12AY7, 12AT7, 5751
Notes: 1. These tubes have common pinouts (9-pin or Noval) and similar voltage ratings. 2. Actual gain factors will vary from manufacturer to manufacturer. 3. Maximum plate current will vary between types of preamp tubes.
Last Edited by on Jun 01, 2012 6:57 AM
Exactly TMF714, as you quite rightly say "3. Maximum plate current will vary between types of preamp tubes." And a 12AU7 draws over 2x the current of a 12AX7 in a typical Fender circuit, no problem for the tube but in the PI of a high voltage amp like a Concert you might be seeing the plate resistors dissipating ~80% of their rated wattage - EDIT - that doesn't necessarily mean that I wouldn't ever do it, if it gives a sound that you just can't live without, then you'll do it...just go in with your "eyes open" ;-) ---------- www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by on Jun 01, 2012 8:45 AM
Sorry - didn't know Paul Linden was also a harp player. Which is why I said "unless". More importantly I agree 100% with Mark - "what sounds right IS right." ---------- /Greg
Linden, I asked him to stop by and participate so I expect he will. MBH is especially good at recognizing players and Paul should be in the conversation around here. Add to it that he's a university professor in Mississippi. Here's an opinion from Jason Ricci:
W E D N E S D A Y , J A N U A R Y 1 4 , 2 0 0 9
Random Thoughts/lists of importance to me you might not know...
23 Underated musicians in my book. Living and Dead. (No Order)
1.) Curtis Salgado 2.) Paul Delay 3.) Pat Ramsey 4.) Chris Michalek 5.) Sun Ra 6.) Roland Kirk 7.) Satan and Adam 8.) Paul Linden 9.) Otis Rush 10.) Shawn Starski
original link: http://jrnb.blogspot.com/2009/01/random-thoughtslists-of-importance-to.html?m=1
5F6H "And a 12AU7 draws over 2x the current of a 12AX7 in a typical Fender circuit, no problem for the tube but in the PI of a high voltage amp like a Concert you might be seeing the plate resistors dissipating ~80% of their rated wattage."
Yikes! Does that apply to a Bassman 50 head? I just got a Kinder AFB+,so I switched back to AX's in the preamp (from AU's) and put an AU in PI(was an AX)
Yes, but what's critical is the voltage that the amp runs (higher voltage, then the more the current whatever the tube & Concerts run the higher end of "normal", in lower voltage amp like a tweed Deluxe/Pro Jr/Blues Jr/Epi Valve Jr/VHT Special 6 I very much doubt you will have any additional problems), a 12AX7 might only draw 1 to 1.5 mA per triode, so even swapping in a 12AU7 isn't going to blow any expensive components (like transformers) at 3-4mA per triode. So don't panic, it's perhaps more of a "Uh-huh" than a "Yikes" situation ;-)
Despite the bad rap the Allen Bradley CC resistors that Fender used get on a lot of techy forums they are very sturdy...even if one fails - worst case scenario - it'll take a while (you sometimes get ghosting & whispery, static noises for a while then one day the amp loses power) & is easy/cheap enough to replace (just like a pot or leaky cap & the kinds of things that fail on any amp).
Truth be told, if I liked the sound of a 12AU7 in such an amp, then I'd run one...if the amp was 50yrs old, precious to me and I was conscious of replacing original parts (personally I'm not) then I'd be 'wary' (perhaps not rule it out completely, just be aware of possible consequences). I appreciate that no one is going to play an amp they don't like the sound of, in the vain hope that it will last forever, if simply subbing a tube makes it "right".
For short-ish periods you are very unlikely indeed to do any harm. ---------- www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by on Jun 01, 2012 12:01 PM
5F6H-Thanks One of the gigs this weekend is a Big Deal. Weather permitting,I'll be playing to a crowd of 1000+. The last thing I want are reliability issues. For safety's sake,should I go back to an AX (or AT)?
AX/AT/5751 all only draw small currents...any of these will give best reliability. But be sure that you're getting a sound you like & can use, the AFB+ should help there...make a judgement call based on tone.
