Bugera 1960 Cascade/RR/1 Wire Mod

[protestsong]

Hi everyone,

I'm a long time reader of the Metro forums but have never posted. I don't own any Metro amps (kits or otherwise), but own plenty of Marshall-like amps and I work on them all. Anyway, this post is for the people that own the Bugera 1960 (first generation, not the new "Infinium" one) that may want more gain out of it. Personally, I like it quite fine stock. With the exception of the coupling capacitor on the lead channel (.0033uf, at least on mine), it's pretty much a dead-on Superlead copy. Quality of parts aside, of course.

So, to those of you that own this amp, know the dangers of high voltage, are handy with a soldering iron and want more gain, read on...




This is the PCB to which the pots and jacks are mounted. I did not take photos to aid in the removal of this board, but it's quite simple:

1. Remove the back panel
2. Remove the chassis from the head shell (6 screws; 1 on each side, 4 on the bottom)
3. Remove the knobs from the pot shafts (it's a pressure-fit, just slide the knobs off)
4. Remove the 4 nuts from the input jacks (use masking tape around the nuts if you're worried about scratching the front panel)
5. From inside the chassis, remove the screws that hold the circuit board to the chassis. Either 3 or 4 screws, I don't remember. I did have to use a right angle screwdriver for a couple of the screws.
6. Remove the shield over the input jacks and set it aside. Put the nuts and washers back on the jacks so you don't lose them.

You can now pull the PCB back from the chassis. Be careful with the pilot lamp, though. You don't need to unscrew the nut on it; that just holds the plastic lens in place. The LED is connected directly to the PCB. Once you've worked the PCB free (again, be careful--it takes some care), prop it up so you can see it like this picture above.

Now, take the 470k resistor (R31) and remove it from the board. Take a new, 1/2 watt 470k and connect it from the top-most part of R31, over to the top of R33. Like this:



That's it! Plug in to the top left input and rock. Just like the 1959RR. Note that this mod will give you the Marshall 1959RR model except for a couple differences:

1. The Marshall has a .022uf coupling cap on the bright channel. The Bugera has a .0033uf.
2. The Marshall has no .68uf bypass cap on the 2nd (or 3rd, if in cascade mode) gain stage. The Bugera has one.
3. The Marshall's bright channel cathode resistor is 2.7k. The Bugera's is 820 ohms.

That's about what I could extract for differences. So the Bugera is brighter and a touch gainier. Oh well. Note that this mod inherits all the flaws of the Marshall, too. Unless you make further changes to the circuit. For some people, this might be enough.

Later,
Eric

[edde]

This is exactly what i was looking for!

Im about to buy a 1960 and do a lot of mods including the RR and power scaling. Some people said that capacitors can be upgraded aswell and of course tubes can be replaced.

How far from a Marshall do you think the Bugera 1960 is in terms of tone quality and tone character?

Edde

[protestsong]

Eddie,

The Bugera definitely sounds like a Marshall. If you trace the circuit, it's easy to see why--it IS a Marshall circuit. It does sound a bit thinner than an amp made with higher quality components, though. It's closer in stock form to the Marshall reissues than it is to an original one, also. Really the only thing I noticed that was a bit different was the .0033uf coupling capacitor on the bright channel. Currently, my amp is set up as such:

Stage 1 / normal channel: 2.2k/.68uf/.022uf
Stage 2 / bright channel: 2.2k/.68uf/.015uf
Stage 3: 820 ohm/no bypass cap/.022uf

All plate resistors are 100k.

It sounds quite good, but not as good as my Laney which has almost the same circuit, but better quality components. The difference is pretty marginal, though. I also replaced the output transformer with a Magnetic Components version shortly after purchasing it. Honestly, it does sound a BIT better, but I wouldn't change it again if I bought a new one. The original transformer was actually significantly louder. Good luck.

Eric

[edde]

Do you have stock tubes in the bugera? What kind of components do you think ruins the tone the most? I've heard resistors is less important, capacitors matters and outputtransformers matters more and tubes maybe matters the most. What about cheap pots?

[protestsong]

I'm not a big fan of the tubes it ships with. The Chinese output tubes sound sterile to me, so I put some Svetlana EL34s in it--really opened up the mids. In my amp, the first preamp tube is an old RCA and the second is an old Sylvania. The phase inverter is stock.

As far as components to change, I'd leave those stock and play the amp for a bit first. If you really must switch component compositions, you're very limited by space, at least capacitor wise. Mallory 150s MIGHT fit, if you're changing coupling capacitors. I didn't bother, except for the bright channel coupling cap, which I changed in value from .0033uf to .015uf. I used an old Philips cap from a PCB Laney. Also, I'm not a fan of the 820 ohm cathode resistors--or at least not the one on the bright channel. You DO have room to use standard 1/2 watt resistors in lieu of the stock 1/4 watt ones in most places. Using carbon comp types for the first couple cathode resistors MIGHT make the amp feel more "vintage." In the end, it's all subjective.

Regarding the output transformer, I'd leave it stock. I changed mine for very little tonal benefit, and lost a decent amount of volume in the process.

Eric

[edde]

I bought the amp today and im gonna open it tomorrow and se what it looks like.

I will do the RR mod switchable (except for the cap). What tubes are stock in a marshall? I dont have any components at all at home and live in the woods in north of sweden so i need to make an order from some website. Do you know a good one?

[protestsong]

Congratulations on your purchase. I highly suggest you play the amp stock first before changing anything, because it really sounds quite good stock. (I have clips if you want.) Anywho... Marshalls of late come with Svetlana EL34s, or at least they used to. Honestly, I prefer JJ E34Ls lately for power tubes. They have this AWESOME lower mid emphasis that other new production tubes just don't have. No idea what they ship with for preamp tubes, but I'd guess Shuguang.

Try it stock. Jump the channels and run the 'Normal' channel at 6-7 with the High Treble channel dimed. EQ to taste. If you want to mod it after that, go for it.

As far as where to get components from, I'm an authorized distributor for Mojo (I repair and modify amps, so I need parts at a decent price point), so I recommend them. For tubes, there's http://www.thetubestore.com" onclick="window.open(this.href);return false; and http://www.tubedepot.com" onclick="window.open(this.href);return false; as well as plenty of others. For resistors and capacitors, the best retail pricing comes from Mouser.

Eric

[edde]

Do you have and sound clips when you compare the bugera vs the laney or another plexi type amp? What model is the laney?

I got some resistors from school today. They are 0.25watts instead of 0.5W as you suggested. Will that matter? If i take two 1Mohm 0.25W resistors and put them in parallell, would that act like 470K 0.5W? They will only be a temporary solution until get some good resistor from a website.

Are you familiar with Kevin O'Connors power scaling? I bought the SB-1 kit and i need to locate the amps "raw bias supply". I cranked the amp in the music store when i bought it but i live in a apartment so neighbours will not be very happy so the power scaling will do it i think. This kit claims to not affect the tone (at least when a included drive compensator also is installed which i yet dont know how to install).

Edde

[edde]

I installed the RR mode now with a switch!

IMAG0017.jpg

(292.56 KiB) Downloaded 9540 times

The green cable is connected on the backside

I see that its very tight around the big capacitors. Isnt it just to put two inches of cable from the pcb to the new capacitor if it wouldnt fit?

The pots for volume and eq looks very bad, do you think they suck a lot of tone? Do extension cables in general suck tone? The bypass circuit looks digital and i really doubt its true bypass, that will also suck some tone?

Im not sure if i know were to find this stages of the amp:

"Va - anode supply; plate voltage to output stage; aka V+ or B+; in the context of the Power Scale circuit, this is the actual voltage applied to the output transformer from the regulator output

Va' - Va-prime; this is the stock plate supply connection on the filter cap positive-end

Vs - screen supply; in the context of the Power Scale circuit, this is the voltage applied to the screen resistors from the regulator output

Vs' - Vs-prime; this is the stock screen supply connection on the filter cap positive-end"

If you know were they are, could you please tell me?

Edde

[protestsong]

Do you have and sound clips when you compare the bugera vs the laney or another plexi type amp? What model is the laney?

I got some resistors from school today. They are 0.25watts instead of 0.5W as you suggested. Will that matter? If i take two 1Mohm 0.25W resistors and put them in parallell, would that act like 470K 0.5W? They will only be a temporary solution until get some good resistor from a website.

Are you familiar with Kevin O'Connors power scaling? I bought the SB-1 kit and i need to locate the amps "raw bias supply". I cranked the amp in the music store when i bought it but i live in a apartment so neighbours will not be very happy so the power scaling will do it i think. This kit claims to not affect the tone (at least when a included drive compensator also is installed which i yet dont know how to install).

Edde

I do not have clips comparing them side by side, sorry. As far as resistors, I only specified the use of a 1/2 watt because you can easily span the gap with the resistor itself without the use of a jumper wire. Plus I don't know many amp techs (tube amp techs, at least) that keep 1/4 watt resistors laying around. Maybe if they primarily work on newer stuff, I guess. Two 1 Mohm resistors in parallel would equal 500k, so you're fine.

I'm familiar with power scaling, but have never tried to implement it, so I'm of no use to you here.

Eric

[protestsong]

I installed the RR mode now with a switch!

IMAG0017.jpg

The green cable is connected on the backside

I see that its very tight around the big capacitors. Isnt it just to put two inches of cable from the pcb to the new capacitor if it wouldnt fit?

The pots for volume and eq looks very bad, do you think they suck a lot of tone? Do extension cables in general suck tone? The bypass circuit looks digital and i really doubt its true bypass, that will also suck some tone?

Im not sure if i know were to find this stages of the amp:

"Va - anode supply; plate voltage to output stage; aka V+ or B+; in the context of the Power Scale circuit, this is the actual voltage applied to the output transformer from the regulator output

Va' - Va-prime; this is the stock plate supply connection on the filter cap positive-end

Vs - screen supply; in the context of the Power Scale circuit, this is the voltage applied to the screen resistors from the regulator output

Vs' - Vs-prime; this is the stock screen supply connection on the filter cap positive-end"

If you know were they are, could you please tell me?

Edde

Your wiring is top-notch. Good work! I don't quite understand your first question. Regarding the pots, wiring and effects loop, I really doubt there's a lot of tone loss going on here. Is it possible with the pots? Sure. Would it be audible? It may be, but it'd be slight, at best. I wouldn't worry about the wiring. As far as the effects loop goes, I have no idea. I'm not going to trace the circuit to find out, either. It is what it is: a (very) cheap, good-sounding Marshall copy made with cheap parts.

Regarding the location of your aforementioned components, I don't have the amp here with me so I can't tell you. Sorry about that. If I had it here, I might crack it open and take a peak for you, but I don't. Let me know how you make out.

Eric

[araysoloartist]

Hi everyone,

I'm a long time reader of the Metro forums but have never posted. I don't own any Metro amps (kits or otherwise), but own plenty of Marshall-like amps and I work on them all. Anyway, this post is for the people that own the Bugera 1960 (first generation, not the new "Infinium" one) that may want more gain out of it. Personally, I like it quite fine stock. With the exception of the coupling capacitor on the lead channel (.0033uf, at least on mine), it's pretty much a dead-on Superlead copy. Quality of parts aside, of course.

So, to those of you that own this amp, know the dangers of high voltage, are handy with a soldering iron and want more gain, read on...




This is the PCB to which the pots and jacks are mounted. I did not take photos to aid in the removal of this board, but it's quite simple:

1. Remove the back panel
2. Remove the chassis from the head shell (6 screws; 1 on each side, 4 on the bottom)
3. Remove the knobs from the pot shafts (it's a pressure-fit, just slide the knobs off)
4. Remove the 4 nuts from the input jacks (use masking tape around the nuts if you're worried about scratching the front panel)
5. From inside the chassis, remove the screws that hold the circuit board to the chassis. Either 3 or 4 screws, I don't remember. I did have to use a right angle screwdriver for a couple of the screws.
6. Remove the shield over the input jacks and set it aside. Put the nuts and washers back on the jacks so you don't lose them.

You can now pull the PCB back from the chassis. Be careful with the pilot lamp, though. You don't need to unscrew the nut on it; that just holds the plastic lens in place. The LED is connected directly to the PCB. Once you've worked the PCB free (again, be careful--it takes some care), prop it up so you can see it like this picture above.

Now, take the 470k resistor (R31) and remove it from the board. Take a new, 1/2 watt 470k and connect it from the top-most part of R31, over to the top of R33. Like this:



That's it! Plug in to the top left input and rock. Just like the 1959RR. Note that this mod will give you the Marshall 1959RR model except for a couple differences:

1. The Marshall has a .022uf coupling cap on the bright channel. The Bugera has a .0033uf.
2. The Marshall has no .68uf bypass cap on the 2nd (or 3rd, if in cascade mode) gain stage. The Bugera has one.
3. The Marshall's bright channel cathode resistor is 2.7k. The Bugera's is 820 ohms.

That's about what I could extract for differences. So the Bugera is brighter and a touch gainier. Oh well. Note that this mod inherits all the flaws of the Marshall, too. Unless you make further changes to the circuit. For some people, this might be enough.

Later,
Eric

Total NEWBIE I AM...sorry for that but ...after this RR1 style mod to my Bugera 1960 Classic does this mean I will use the Vol1 and Vol2 as GAIN now??....instead of ripping my head off with its loudness as it is now...Im in search of this mod as well as the PPIMV mod for the Bugera 1960...but Im a total newbie with good soldering skills...but no mod experience on amps...

[protestsong]

Plugged into the top right input, you now have the normal channel running into the treble channel. Volume 2 will be your control for how much volume from channel 2 (the normal channel) gets sent to the next gain stage, which is the high treble channel. Volume 1 is your control for how much volume from the treble channel (as well as the previous stage, the normal channel) gets sent to the third gain stage. So there is no master volume by doing this mod alone, per se. Also, anyone doing this mod would do it justice to consider AT LEAST changing the cathode bypass cap on the first stage to something much smaller. Maybe 1uF or .68uF.

Eric

[araysoloartist]

So if Im understanding , this mod REPLACES the jumper you would run to get these options...amp works just like it would with no need to use a patch cable. Doesn't add any more distortion etc. Very cool !
Thanks for the speedy reply ! You RAWK !

[protestsong]

No, you do get more gain with this mod. Linking the inputs with a patch cable, you're running both channels in parallel--side-by-side. With this mod, you're putting the two channels in SERIES, giving you three stages of gain instead of two. More gain, but no master volume unless you mod it further. Hope that helps.

Eric