Amp gain question (Myles?)

[TurboDog]

Why is it, that I much prefer my preamp gain to my power amp gain (distortion?)?

 

Everybody talks about baking your power tubes to get sweet distortion, but I find this tone to be very harsh, and not smooth at all. I can dime my preamp volume and get a creamy distortion. (Rivera 30-12).

 

I even pulled a tube to get more heat into the remaining tube (30 watts can get awefully loud) with no improvement.

 

Normally I would just accept this as a matter of taste and move on. But my sound guy wants me to come off the front end and turn up the back end to get a better sound for mixing.

 

Additionally, I don't like mids that much. I can't bear turning up my mids past 4, maybe 5. But a lot of people recommend cranking the mids to cut thru.

 

So am I stuck with a lot of mids thru back end overdrive? I may cut thru, but I'll sound like ASS.

 

Any suggestions/comments?

[Bonedog]

I'll bite, why do you like preamp gain more than power amp gain?

 

It's hard to tell without hearing your rig but with an open back cabinet (and with most amps) turning your mid up to 5 or so should be enough, that's provided you don't have your treble and bass set to stun. What kind of music do you play, what sound are you going for? A guy told me when I was younger that "guitar is a mid voiced insrument, why rob it of it's voice...?" It took me a while to get used to the sound, but once I got used to it...now I can't go back. How long have you been playing? I find with most players, the first few years, everyone goes through the scooped mids thing and you get used to that sound.

 

About pulling power tubes, is that ok to do with your amp. You can do that with some amps but what happens is that your power gets cut in half, one tube doesn't get "hotter". You should really check with a technician to see if that's ok to do with your amp. It could end up being an expensive mistake...

 

As far as sounding like ass goes, if your sound is balanced (not too much or too little of anything) you shouldn't sound like ass.

 

Hope this makes some sense,

Scott

[Gabriel E.]

Pulling a single tube out of 2-tube amp is a BAD idea.

 

Pulling 2 tubes (check the schematic to see which ones, you can't pull them at random) out of a 4-tube amp is ok but will alter the output impedence and require rebiasing.

 

How does your sound work in context of the band? I used to use what I thought was a great tone - until I played with drums and bass and it dissapeared. Often a honky midrange will sound like ass by itself but will sound splendid in a band.

[myles_rose]

Originally posted by TurboDog:

Why is it, that I much prefer my preamp gain to my power amp gain (distortion?)?

 

Everybody talks about baking your power tubes to get sweet distortion, but I find this tone to be very harsh, and not smooth at all. I can dime my preamp volume and get a creamy distortion. (Rivera 30-12).

 

I even pulled a tube to get more heat into the remaining tube (30 watts can get awefully loud) with no improvement.

 

Normally I would just accept this as a matter of taste and move on. But my sound guy wants me to come off the front end and turn up the back end to get a better sound for mixing.

 

Additionally, I don't like mids that much. I can't bear turning up my mids past 4, maybe 5. But a lot of people recommend cranking the mids to cut thru.

 

So am I stuck with a lot of mids thru back end overdrive? I may cut thru, but I'll sound like ASS.

 

Any suggestions/comments?

TurboDog...

 

Some folks like preamp distortion and overdrive, some prefer output compression and overdrive. Its just a matter of personal taste.

 

For singing lead solo work, the preamp overdrive is usually favored. That is how the Mesa Boogie amps were generally designed, with very high gain front ends. Some of their amps have 245 volts on the preamp tube plates, compared to a Fender Deluxe with about 170 volts.

 

One of the reasons a Marshall has a different sound than a Fender is also the higher gain in the front end, as well as the tone stack and some other items.

 

On output tubes, they need to be driven close to their limits for their sort of distortion. On some amps, this is pretty hard to do without causing some legal recourse to follow. On a 100 watt Marshall or Hiwatt head, this is very loud. Some folks use power brakes or hot plates by THD to drive the amp to higher levels while keeping the sound output at rational levels for residential areas

 

The Rivera amps are a bit different than a lot of other amps in a few ways. For one thing, as a comparison, a Mesa Mk series uses cascading gain ... one preamp triode feeds a second triode. In Rivera amps, they run the two sides of a dual triode in parallel, rather than in series, and therefore get a lot of headroom and gain is accomplished in other ways that are more engineering savy and more expensive. Listen some time to a Rake head or Knucklehead ... all the gain you'd ever want or need, but not the graininess of a Mesa Rectifier. Different tastes for different folks.

 

Your particular amp is a great blues amp if you turn the master all the way up and keep the preamp down, so you get that output distortion and compression going. On the other hand, if you want that gain for sustain, hammper-ons and tapping ... then crank the preamp gain and dial back on the master. Your amp is very versitile.

 

Don't pull a tube. You will imbalance the output stage and change the impediance. This can result in output transformer failure .... actually it will, in pretty short order. If you want to drive your amp hard, use something like a THD Hot Plate ( www.thdelectronics.com ) That is also something your sound guy will like.

 

On your issue with mids ... its all personal taste. Its your sound, and sometimes being happy with what you like should take precidence over what the engineer is asking you to do. You can listen to the end result once its "printed" and then go back and retrack using different setting to compare. Things do sound different live vs. recorded, and this is where an engineer can help.

 

I don't know if any of this actually helped, as this is all personal preference, and you seem to know what you prefer. Its up to you to convince your engineer that you want a certain sound, and he should be able to give that to you.

 

Regards,

[TurboDog]

Thanks for the posts. By the way Gabriel, I'm a native CrescentCity-ite.

 

I only pulled the second tube for about 2-3 minutes. I know it cuts power, that's why I pulled it. So I could crank the volume (poweramp) and get more tube breakup. Cranking a 30 watter to 8 or 9 in my living room isn't too plausible.

 

I've been playing for several years. Most of what I play is classic rock to hard rock. I typically play with another guitarist, who plays rythym mostly with acoustic, sometimes electric. I do the heavy rythym and leads (rarely long leads, mostly little riffs and fills.)

 

I love the lead tone when my preamp is turned up. The tone I get from more power-amp breakup isn't as sharp or clean.

 

Of course, rythym is a whole different animal. Some songs require very little breakup. I use the 2nd channel, the American voiced channel for that. I actually like that channel with power amp breakup.

 

For songs with heavy gain rythym, I use channel 1 with a lot of pre-amp gain and work the volume on my guitar to soften up when necessary.

 

The best way I can describe the power-amp distortion is that it's very rough and abrasive, whereas the preamp is much smoother.

 

I don't use pedals really. I use a wah and my amps channel/boost switching pedal and that's it. I use a delay occasionally. So it's just my guitar and amp. I used to use a chorus, compression, and dist. pedal, but they've been closeted.

 

As for the mids, I have my dirty channel at 4, and my clean at 7. Any higher on the dirty channel and I get this nasty look on my face. I understand mids may be an acquired taste. But anything could be an acquired taste. A friend tries to sell me on Guiness beer. "It's an acquired taste" he says. "So is drinking piss," I tell him.

 

Anyway, thanks again for the comments and any more that you may have for me.

 

Maybe a tube replacement is in order...

[Gabriel E.]

Should have known from your name. I love Abita too.

 

Chilly today huh?

[TurboDog]

Cold up here in Huntsville for sure.

 

Thanks guys for the info. Myles, as always, you gave me some great info. I absolutely agree that for bluesy tones I kick up the power amp and drop the pre. Usually on channel 2 though.

 

The preamp gain on channel 2 gets ugly pretty quick, which I know is a problem for some Rivera models. Some people have changed tubes and speakers and been very satisfied. I'll work on this in the future.

 

Anyway, thanks for bringing me over to musicplayer. Much less BS to weed through.

[myles_rose]

Originally posted by Bonedog:

I'll bite, why do you like preamp gain more than power amp gain?

 

It's hard to tell without hearing your rig but with an open back cabinet (and with most amps) turning your mid up to 5 or so should be enough, that's provided you don't have your treble and bass set to stun. What kind of music do you play, what sound are you going for? A guy told me when I was younger that "guitar is a mid voiced insrument, why rob it of it's voice...?" It took me a while to get used to the sound, but once I got used to it...now I can't go back. How long have you been playing? I find with most players, the first few years, everyone goes through the scooped mids thing and you get used to that sound.

 

About pulling power tubes, is that ok to do with your amp. You can do that with some amps but what happens is that your power gets cut in half, one tube doesn't get "hotter". You should really check with a technician to see if that's ok to do with your amp. It could end up being an expensive mistake...

 

As far as sounding like ass goes, if your sound is balanced (not too much or too little of anything) you shouldn't sound like ass.

 

Hope this makes some sense,

Scott

It is not OK to pull one tube of a pair. Its also not OK to pull one tube of a quad.

 

If you have a 100 watt amp, or something with a quad and an impedience selector, you may make it into a 50 watt amp by pulling one "pair" ... usually the center two tubes OR the outer two tubes. You then have to cut your impedience in half. That means if you have an 8 ohm cabinet, and pull two tubes, you then need to set the impedience selector to 4 ohms, even though you are connected to an 8 ohm load.

 

Failure to follow these guielines will probably result in a blown output transformer.

 

Regards,

[myles_rose]

Originally posted by TurboDog:

Cold up here in Huntsville for sure.

 

Thanks guys for the info. Myles, as always, you gave me some great info. I absolutely agree that for bluesy tones I kick up the power amp and drop the pre. Usually on channel 2 though.

 

The preamp gain on channel 2 gets ugly pretty quick, which I know is a problem for some Rivera models. Some people have changed tubes and speakers and been very satisfied. I'll work on this in the future.

 

Anyway, thanks for bringing me over to musicplayer. Much less BS to weed through.

TurboDog ...

 

From your earlier post, where you thought a new set of tubes may be in order .... I don't think so. For a few minutes, there was no damage.

 

In a Rivera amp, the transformers, both power and output, are about 3x the cost of a Marshall or Fender transformer, or I should say, 3x the quality. A typical Rivera amp's transformers are very over designed, and that's why their amps put out considerably more power than their ratings. If your amp sounds fine now, you probably did not do any damage.

 

Rivera amps are generally voiced USA on channel 2 and Brit on Channel 1. Channel 2 on his amps can do the Fender "things" very well, and Channel 1 are more of the higher gain Marshall flavor.

 

Regards,