CALIBER 50 +

[jeid2000]

I am also a new .50 caliber + owner and i am fighting a high end sizzle that I can't seem to get rid of. I tried a 12au7 but I think it's too low gain. I have tad power tubes and tried some jj's which sounded worse. I have a jj 12ax7 a mesa boogie 12ax7 and I think the other 2 are eh.I can't get a smooth sound in the lead mode I think it has to be tubes.

EVM-12L speakers quench fizziness, for sure!

Someone has mentioned on the forum that the only lead channel uses V1, and that the rythm channel starts at V2. Sounds reasonable, but I cannot confirm this. :?

I'm pretty sure this is the case with most amps. IF you read the instruction Manual for the .50+ it says if you get a microphonics squeal only on the lead channel, then replace V1. I'm pretty sure it says the same about the rhythm channel and V2.

 

[user 7737]

I have a jj 12ax7 a mesa boogie 12ax7 and I think the other 2 are eh.I can't get a smooth sound in the lead mode I think it has to be tubes.

i'm very doubtfull about the EH, i just can't have something clear with them... does everybody here play metal or stuff like that ? high gain tubes like TS reduce the versatility of the amp... i think...

IF you read the instruction Manual for the .50+ it says if you get a microphonics squeal only on the lead channel, then replace V1. I'm pretty sure it says the same about the rhythm channel and V2.

i'm sure it's a bit more complicated... V1 influences both rythm and lead

 

[lpstudio]

I know if I put the 12au7 in v1 it doesn't effect the volume much but if it is in v2 the volume is way less. I think I will try an 12at7 in v1 as well

 

[stomper]

Someone has mentioned on the forum that the only lead channel uses V1, and that the rythm channel starts at V2. Sounds reasonable, but I cannot confirm this. :?

It is true. V1 is only functional in the lead channel.

I bought my 50 cal.+ new in 1990. I do my own repairs and just overhauled it last week. It sounds better than when it was new. There are schematics on the net if you look. Boogie will send them to you also. I don't want to post a link as R. Smith is protective of his schematics by non-owners/cloners. I will say this amp is a major pain in the behind to work on. You may have trouble finding a local tech willing to take it on if it needs repairs. That said, I have a few tweaks you may be willing to try if you are looking for a more balanced, full bodied tone that has less fizz and less midrange honk. The amp will have more bottom at low volume. If you find yourself diming your rhythm channel bass pot and want more, this is for you. If anyone is interested, I will make a followup post.

 

[Sludgenutz]

Someone has mentioned on the forum that the only lead channel uses V1, and that the rythm channel starts at V2. Sounds reasonable, but I cannot confirm this. :?

It is true. V1 is only functional in the lead channel.

I bought my 50 cal.+ new in 1990. I do my own repairs and just overhauled it last week. It sounds better than when it was new. There are schematics on the net if you look. Boogie will send them to you also. I don't want to post a link as R. Smith is protective of his schematics by non-owners/cloners. I will say this amp is a major pain in the behind to work on. You may have trouble finding a local tech willing to take it on if it needs repairs. That said, I have a few tweaks you may be willing to try if you are looking for a more balanced, full bodied tone that has less fizz and less midrange honk. The amp will have more bottom at low volume. If you find yourself diming your rhythm channel bass pot and want more, this is for you. If anyone is interested, I will make a followup post.

Hey, I'm all ears!

 

[user 7737]

Hey, I'm all ears!

so do I...

 

[jeid2000]

Yeah... also interested

 

[stomper]

[/quote]
Hey, I'm all ears![/quote] Cool. This may take a while for me to compile, but I'll do what I can in segments. I'll start with the easy ones.

Depending on the year of your amp, there is a 22k resistor in the reverb circuit that needs to be 2 watts. Early amps like mine came with a 1 watt resistor and it is underrated. It will actually be melted when you check it. It may even smoke and smell bad when the amp gets really hot. My amp still melts the 2 watt resistor! I spoke to R. Smith on the phone about it and he said to leave it at 2 watts, it won't fail. He designed the circuit to do this. :roll:

Okay ducking for this one......Have your tech put in an adjustable bias pot. The 50 cal. came with two resistors in parallel. 82k and 68k. The sum resistance is 34k. Easy to find on the schematic. All tubes will drift in their bias over the life of the tubes. Making periodic adjustments is key to getting the sound you like. Once you have the bias pot, you have more options. You can leave it at 34k and keep using Boogie tubes forever. You can also use whatever tubes you want and have your tech bias it for you. I like the new Tung Sol tubes a lot. Even the Boogie tubes will benefit from setting them exactly where you want them. Fizzy sound? Thin tone...check the bias. Running the tubes a little hotter might do the trick for you.

Obtain a few spare LDR Vactrols. They do burn out(especially if you channel switch) and if you have one on hand, you can replace it without going without your amp until the part comes in.

The coupling capacitors to the power section are .047uf. Change these to .1uf for a fuller low end. Bigger caps here will balance that fizzy top end and honky midrange to a nice even tone in both channels. Look at the Fender Blackface Twin schematic. Fender used them for a reason. If I had to guess, R. Smith went with the smaller cap to give the amp more percieved loudness. If the amp has less bass to amplify, it will be able to make the midrange and treble louder.

Okay, I have put forward some things that I feel are crucial to getting a great tone from the 50 Cal. more to come as I neaten up my wiring diagram for you.

 

[scottcrud]

"Obtain a few spare LDR Vactrols"

And where would one find these? Are these also known as Opti-couplers?

Thanks, Scott

 

[lpstudio]

wow very interesting thanks a bunch. I was trying a bunch of different tubes tonight power and preamp and I can't tame the fizz. I want to like this amp but next to my old Traynor mark3 head it sounds like crap on the lead channel

 

[user 7737]

****... That requires some real technical skills :?

i like this amp but we have to be industrial engineer to handle it

 

[stomper]

****... That requires some real technical skills :?

i like this amp but we have to be industrial engineer to handle it

Unfortunately, yes. The good thing is, once tuned up it is very reliable.

 

[stomper]

"Obtain a few spare LDR Vactrols"

And where would one find these? Are these also known as Opti-couplers?

Thanks, Scott

Right, optocoupler is another name. Try tubesandmore.com. I feel sorry for the MarkIV owners because those amps probably use a bunch of them. And you know those guys are switching channels often. At $9 a pop it will add up quick.

If you need to change a vactrol, don't unsolder the part from the board. Just cut the leads as close to the old one as you can. Heat sink the original leads(they are very skinny) and solder the new part to those leads. The less you stress the board and the copper traces underneath, the better. Try this when replacing just about any part in the caliber Boogies. These amps are too hard to work on to risk messing up traces.

 

[stomper]

wow very interesting thanks a bunch. I was trying a bunch of different tubes tonight power and preamp and I can't tame the fizz. I want to like this amp but next to my old Traynor mark3 head it sounds like crap on the lead channel

Glad to help. I've never worked on a Traynor, but they are reputed to be a near copy of a Marshall plexi, and very well built. That is mostly power amp distortion. It sounds richer harmonically, and feels better when playing. The amp is very touch sensitive to what you play on the guitar. I can't cop an old Aerosmith tone with the lead channel of my Boogie. It totally gets the Metallica thing though. I like the Fulltone OCD with my rhythm channel of the 50 cal. better than the Lead channel of the 50 cal. If you look at the schematic, you will be surprised at how rudimentary the lead circuit really is. It is only 7 parts, including the tube.

 

[lpstudio]

I was thinking of driving the rhythm channel of the boogie as it sounds great

 

[slayer44]

Im a proud owner, wouldnt get rid of it if my life depended on it. I use it primarily for 80s thrash, and its got the fastest attack of any amp Ive played. I recently switched v1 and v2 to the new mullard reissues, and they made a HUGE difference in the tone. I run Ruby 6L6GCs in the power section and a eh12at7 in the PI slot. Ive tried JJs, =C='s, GTs, Mesa, Svetlana, and Sovteks in the power section, and the only ones I wouldnt recommend are the JJs (although I like them in my 5150). They made the amp too aggressive, while the SED =C=s were a close 2nd to the Rubys. My settings seem to have alot more low end than the others that have posted settings. I have to keep it on about 7.

 

[scottcrud]

mine isn't fizzy at all, guess it's cause I had the tiny power and output transformers yanked out of there and had 100 watt power and output trannies installed. And the 6550's don't break up like the 6L6's...

 

[jeid2000]

How many cabs can you run off of a .50 C+?

It's got three outputs, anyone know if you can run 3 cabs from it safely? I've never tried.

 

[Whoopysnorp]

Right, optocoupler is another name. Try tubesandmore.com. I feel sorry for the MarkIV owners because those amps probably use a bunch of them. And you know those guys are switching channels often. At $9 a pop it will add up quick.

If you need to change a vactrol, don't unsolder the part from the board. Just cut the leads as close to the old one as you can. Heat sink the original leads(they are very skinny) and solder the new part to those leads. The less you stress the board and the copper traces underneath, the better. Try this when replacing just about any part in the caliber Boogies. These amps are too hard to work on to risk messing up traces.

Does anybody know if the Studio Preamp uses these for switching too? I know I've read that these commonly wear out in the Studio Pre. My Pre is fine, but my roommate's doesn't switch cleanly between lead and rhythm...the lead tone kind of 'dissolves' into the rhythm tone in the space of about a second.

 

[stomper]

The Studio Preamp uses the vactrols also.