Showing posts with label GZ34. Show all posts
Showing posts with label GZ34. Show all posts

Tuesday, December 1, 2015

'65 Deluxe Reverb Re-issue. This offends me!


 Today we have what I consider to be one of the best values on the marketplace today: a good ol' Fender '65 Deluxe Reverb reissue. Classic design, perfect club amp for those who like the black panel Fender sound. 22 watts of power through a pair of 6V6 tubes. There was a time when if I had a dozen original ones in my store they would be gone in a month. Everyone seemed to want one about 15 years ago. Now the watts war is in reverse and that honor goes to the Princeton Reverb. Those sell effortlessly enough that Fender made a re-issue of those as well. I prefer the Deluxe myself.

  So hopefully my headline got your attention. These are great amps but there are a few things about modern construction that just bum me out. This one was dead, no big deal, just had a burnt 6V6 tube. The fuse didn't pop so the 470 ohm 1 watt screen grid resistor burned up. Again, no big deal.

  In the old amps Fender put the 470 ohm screen resistors on the tube sockets along with the 1.5k grid stop resistors. To cut cost they put these on the circuit board. When one burns up, and it is a dramatic burn, it makes a mess. Here is the socket:



And here are the burnt resistors on the board:



So first step is to cut those resistors out and clean up the board with sandpaper and compressed air. Get as much of that carbon out as you can.



  Next I bypass where the old resistors were. I also bypass R60 & R61, the grid stops. I will be moving those to the sockets as well. Why? They should be on the sockets. They don't always work when they aren't. Why risk that? I've seen it happen before, having them on the board doesn't prevent oscillation at high volumes. Simple fix.



  Now admittedly, I'm cutting a corner here too. The proper way to do this is to remove the board and remove the resistors, then replace them with a solid piece of wire. Do as I say, not as I do. This does add time to the job but we are on a budget and this works just fine.

  Here are the re-wired sockets:




  Notice I moved the orange from pin 4 to 6 and put the 470 ohm, now 2 watt resistor between 4 and 6. I also moved the green wire from 5 to 1 and put nice sounding carbon composition 1.5k 1/2 watt resistors between 1 and 5. This is how they did it in the glory days of amp building.

  Now if a tube blows again, there is less mess to clean. I feel better about the whole thing. Not to mention, if we were to put those screen resistors back there they were, the next time they burn, they will burn a whole through the board most likely, then we'll have a real mess! Prevention is easy on these amps. Do this and save yourself trouble down the road!

JB

Thursday, June 18, 2015

'59 Bassman Reissue

One of the most sought after amplifiers in the world is the Fender tweed Bassman produced from about 1958-1960. There is a good reason for that. It really is a Swiss Army Knife that can handle just about any gig with the exception of metal, but even Eddie Van Halen enjoyed one of these. Trouble is to find an original you need a bankroll like fast Eddie, they can command prices upwards of $10K in great condition. I remember the first one I ever tried, that was at Mr C's Music in Marlboro, Massachusetts. My dear friend Shawn Clement's pop owned it (remember mom and pop music stores?). It was an ugly example and this would be in 1986. The tweed was removed and the pine box had a walnut stain to it. This was the days before people started re-tweeding, relic weirdness etc. You simply played the things and made them better looking in your eyes. I thought is was really cool looking actually and when I played it, though it had no 'overdrive' channel or reverb, the sound I could produce with my 18 year old fingers got me curious about old amps. It was around the next year (1987) that I went to the NAMM show with the Clement family and Fender introduced the '59 Bassman Re-issue. I'm a lifelong Fender fanatic so this totally caught my eye.

Todays example is one from right around that era. It has the blue Eminence speakers rather than the trashy sounding Jensen Re-issues. True story, I had a totally stock Re-issue Bassman from this era and a Victoria version (all hand wired, very nice amp!) that had my least favorite caps and speakers, the Jensens and those 715P orange drops. I had a bunch of my customers play them and they all preferred the re-issue. When I told them it was just an $800 stock re-issue amp, none of my customers believed me. So yeah, these are really good amps.


This particular one was making no sound at all. Dead. That part of the problem was easy to solve: one of the speakers, which are wired in parallel had shorted out. Zero ohms. Unusual. In 25 years I have maybe seen this once, and that could be my memory inventing stories. So I replaced it with an Eminence alnico. Same great speaker as far as I can tell, and I'm a fan of Eminence speakers in general.



Control panel. Yes, those of you who know amps already know this. This is the amp Jim Marshall copied when he made the even prettier Marshall amplifier. Circuit is nearly identical, layout is nearly the same and they are both lovely amps. Those of you who may find that morally objectionable, nothing is original. Fender merely copied old Western Electric and RCA circuits and elaborated on them. That is the fun of tube amps. Copy then experiment!



This amp was also modded, or, hand-wired. Not the tidiest job but still well done:



I've done these before. I prefer to go the old fiberboard route. More room for cooler capacitors. Curiously these are the same caps that Fender uses in there modern amps. Why go to all the trouble if you're not going to do something different. Still, this is an improvement and the person who owns it is selling it. The next buyer is getting something that would sell for a lot more if it were 'boutique'.

This part I didn't like:



Very well done but no cover for the filter caps. Not that anyone will be reaching up there during a gig while it's on but, man, this is dangerous. Also the 2 main filters are 220@350v in series giving you 110uf. With a tube rectifier you really don't want to go above 50. It can cause a drain on that tube and on the 5V filament winding. Or at least this is what the old RCA manuals say and I trust them.

Using such a large filter in your first stage gives you the benefit of improved low end and overall more headroom, plus it's quiet. However, most folks like a little sag and compression. I changed them to 100uf each giving me 50 total. Hum? Nope. Very quiet.

Also had one noisy preamp tube and after a cleaning and tightening every bolt (many were really loose! Output transformer was barely hanging on!) then it was a wrap! Great sounding amp. If I ever decided to go big againit would either be one of these or a Vox AC30 or a Marshall Bluesbreaker. Either re-issue amps so I can actually play them live without worry or I'll build one myself. I had the honor of re-building Jimmy Vivino's Bassman Re-issue years ago and I heard it became a favorite of his. Allegedly Slash rocked it and fell in love too. That amp I simply took out some funky mods and re-tubed it. These are great amps. If you can find an early one like this even better. If you can pay me or someone else you trust to hand wire it then you have something that is really just as good as a $10,000 original! Why pay more?

J