Power amps!

Re: Power amps!

Postby Jon S. » Mon Apr 23, 2012 9:06 am

A 3db increase is double the volume - i.e. 103 db is twice as loud as 100 db.

Respectfully, the above is inaccurate.
an increase of 3dB results in a voltage increase 1.4 times the original, a doubling of power, and yields only a subjective increase in loudness only 1.23 times the original. To get a doubling of loudness, it is important to note that an increase of 10dB is necessary.

Source: http://www.gcaudio.com/resources/howtos ... dness.html
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Re: Power amps!

Postby strumminsix » Mon Apr 23, 2012 9:16 am

I always thought the calc was: you need to double your power to increase 3db. And let's be clear, 3db is ALOT. 2db is about the difference between a lead and rhythm instrument.
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Re: Power amps!

Postby Rusty the Scoob » Mon Apr 23, 2012 9:50 am

Thanks for the correction, Jon S!
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Re: Power amps!

Postby Jon S. » Mon Apr 23, 2012 10:21 am

It's all cool & strumminsix and you are certainly right that an 3db increase is quite significant in its own right as anyone who has changed from a 97 db to 100 db-efficient speaker can attest (though more volume doesn't necessarily mean better tone!).
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Re: Power amps!

Postby Jon S. » Tue Apr 24, 2012 3:54 am

wolftigerrosebud wrote:I'm actually looking to try something different in the power amp area this summer... the Rocktron is a pretty good sounding amp, but I noticed when I was playing with some friends at a party a few weeks ago that the sound is too thin sounding. Here's the video: [deleted for this response]

Rig I'm using now is a USA Hamer Artist with split Super 2s -> effects (all "true bypass", Dist +, Big Muff, Earth Drive, Q-tron, Phase 100, but none active here) -> SMS JG mod w/ PRPs -> Rocktron amp -> Eminence Commonwealth 12. I'm confident in the top-notch quality of all those components except for the power amp.

Anyway... I want a ballsier sound. Anyone have any ideas? The Mesa 50/50's been on my mind... I'd go for a mac but there really aren't any good electronics repair places around where I live and I'm reluctant to buy old electronic equipment because of that.

Brief iPhone reply now, more following your responses. What exact Rocktron model are you using? How much, if at all, have you experimented with varying the relative levels/settings of your guitar, preamp, and power amp (makes a huge difference - getting the balance right was my key to max results from my own Rocktron'). Have you tried buffering your signal (all true bypass effects may be sucking your tone by the time it reaches your preamp)? Bottom line is follow Treebeard's advice: Don't be hasty. Before you convince yourself you need yet another piece of hardware, know & tweak what you've already got.
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Re: Power amps!

Postby wolftigerrosebud » Tue Apr 24, 2012 7:03 am

Good advice Jon... No, I haven't tried buffering my signal, mainly because I'm not 100% sure what you mean by that. You mean adding a buffer like Brad's or Waldo's? Using a V300 btw.

I have actually experimented rather extensively with the power amp settings, the guitar's volume and tone pots, and the preamp's output level. It still doesn't give me... something. It's almost too dark, there's a kind of snap that I feel like I can't get from the amp without it sounding shrill.
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Re: Power amps!

Postby Jon S. » Tue Apr 24, 2012 7:12 am

Now we're getting somewhere. I'm using a RV300, also. My chain is my Philtone J-caster w/on board CAE buffer into a Line 6 M13 into an SMS Classic Preamp into the RV300 into a SSP Jerry vertical 2X12 w/a Jensen Neo on the bottom (for lower mids girth) and Weber NeoMag on top (for not-identical-to but JBL-like upper mids). I have many thoughts and a few suggestions for things you can try with your unit, including some more esoteric steps you may not have thought of at all, but a conversation would be better than trying to type it all out back and forth. If you want me to give you call, feel free to PM me a number and tell me when it's best to call. I can say, though, that while it's a fair argument that an RV300 is never going to sound truly = a Mac, used correctly, it should be neither thin, dark or shrill (interesting combination of comments on your part, BTW, I can't say I've every had an amp that did all 3 of these simultaneously!).
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Re: Power amps!

Postby strumminsix » Tue Apr 24, 2012 7:23 am

wolftigerrosebud wrote: It still doesn't give me... something. It's almost too dark, there's a kind of snap that I feel like I can't get from the amp without it sounding shrill.


that's odd. What is your toggle set at on the SMS? How high is your reactance on the RV?
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Re: Power amps!

Postby Jon S. » Tue Apr 24, 2012 9:26 am

Waldo is going to say "I told you so" if he reads this but these days, my SMS is set w/the bright switch in the middle setting and treble full on, bass very close to on 0, and mids at around 2PM, and the reactance and definition on my RV300 at around 10AM and 3PM, respectively. (I will admit, though, to having set up a model on my M13 using the Proco Rat model with the volume dimed and the distortion barely on just above unity gain for when I, myself, desire extra "snap" to my tone.)
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Re: Power amps!

Postby wolftigerrosebud » Tue Apr 24, 2012 10:37 am

it should be neither thin, dark or shrill (interesting combination of comments on your part, BTW, I can't say I've every had an amp that did all 3 of these simultaneously!).


Lol.... Yeah, those are kind of contradictory descriptions, aren't they? Wasn't specific enough: shrill sounding when the definition's up, unpleasantly dark when the reactance is up, and generally kind of flat-sounding, not so much thin. There's a certain mid-rangey smoothness and lack of definition to it (and the definition knob increases that definition but not in what I find to be a pleasant way). I'd really prefer something with more snap to it, but snap that's both clean and with a great deal of presence and that's aurally pleasing to me in the same way Jerry's snappy guitar sound is to my ear. So I was thinking just getting a power section that's similar to an old blackface Fender Twin might solve my problem, or that it may be time to try a Mac. When it comes down to it, it's not that I want more mids, highs, or lows. Just that I want it to sound right to me. It may also be the Commonwealth. I know that it's a pretty bassy speaker. But I dunno... when I switched to the commonwealth from an Emi RWB it was a huge improvement to the sound, so I'm not inclined to think it's the speaker.

Similar thing happened when I went to buy a bass amp back when I was playing bass. Plugged into a WT800 and plugged into an EA iAmp Pro, and I just didn't like the way the Eden sounded. The EA sounded a million times better to me, so I bought that one. Which is crazy, I know -- Eden makes great gear, Phil uses it, etc. But I have pretty sensitive hearing and it's really just taste, which is hard to predict or cater to.

I actually read your V300 settings a while back in a different thread, and I've tried the 10 for reactance and 3 for definition, and they just don't sound right to my ear anymore than the rest of the amp sounds "right" at other settings. Sound is such a subjective thing -- in the end, all I'm trying to do (all we're all trying to do) with all this gear is elicit an emotionally pleasing response.

But, having played with the reactance and definition knobs in different positions, I've just been turning them both off all the way. It sounds worse to me with them on, so my thinking is that minimizing damage might be the best course of action. So I leave 'em off. That may be a poor choice, and if y'all think it is, I'd love to be able to try out any recommendations you have.

Settings on SMS are bright switch on middle position, treble at 10, mids at 4-6 depending, and bass all the way off or close to all the way off.

Edit: I realize that doesn't leave a lot of room for recommendations with the power amp I currently have (though I'm open to any and all), so it kind of brings me back to my initial question... thinking a different power amp may be the answer to this tone issue for me. If anyone has suggestions I'm open. My ideal amp would just be getting a fuckin MC2300 already, or a 2100 or a 2150 would also be fine. That being said, though, I'd prefer something new because there are no decent electronics repair places around here, and with vintage electronic gear I don't doubt that I'll run into more technical issues than with newer stuff. Got some nice bass gear to sell (lol) to fund that particular project, so let's say, for the sake of opening up suggestions, that money is no object up to around the $2000 line. I'd also really like to be able to buy something that I could go and hear and play through in person first -- personal recommendations are only so useful.
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Re: Power amps!

Postby hippieguy1954 » Tue Apr 24, 2012 12:01 pm

I used to own the V300 also. Jon S. and I have compared notes a bit on this.

I also have a SMS Classic/Jerry mod. The best sound I got (and it was very good) was with the same settings as you are using on the SMS but on the V300 I'd use 0 for reactance and 3 0r 4 for definition.

I set the Volume on the SMS at about 4 or 5. I set the SMS gain control (on back) on 6 or 7. I leave these setting the same all the time.

I adjust the volume for room size etc. with the volume control on the V300.

I'm not very familiar with the speaker you are using, but I know from years of experience that it is hard to get JBL E120 tone from any other speaker.

Also, what guitar and pick ups are you using? :smile: :smile: :smile:
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Re: Power amps!

Postby Jon S. » Tue Apr 24, 2012 12:06 pm

wolftigerrosebud wrote:I actually read your V300 settings a while back in a different thread, and I've tried the 10 for reactance and 3 for definition ...

Holy missettings, Batman! You'll have to show me where I wrote to use those settings (they'd not occur to me in million years!).

The short version: the RV300 inputs are not sufficiently padded, in my view (and that of some others I've spoken with), for most guitar pickups. The way to deal with this is to pre-set your SMS's front panel output level at between 9 and 10 o'clock, ONLY. Then bring the level up using the SMS's rear pad control to taste. YMMV but my experience is that anything over 10 o'clock on the SMS's front panel output control will overdrive the RV300 - something we don't want for Jerry tones. With my SMS's front panel output control set low, I then simply bring up the volume to taste using the RV300's volume controls and it works for me.
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Re: Power amps!

Postby strumminsix » Tue Apr 24, 2012 12:09 pm

Wow, that Commonwealth is a mid-heavy speaker.

You should try:
1. flipping on the bright switch
2. drop your bass to 0
3. start with your treble on 8
4. bring up your mids for your needed low end
5. adjust treble for clarity
6. turn up the volume!
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Re: Power amps!

Postby wolftigerrosebud » Tue Apr 24, 2012 1:00 pm

Holy missettings, Batman! You'll have to show me where I wrote to use those settings (they'd not occur to me in million years!).


Right here:

and the reactance and definition on my RV300 at around 10AM and 3PM, respectively.


I didn't mean that I had the reactance dimed and the definition on 3. Was just writing kind of quickly.

The way to deal with this is to pre-set your SMS's front panel output level at between 9 and 10 o'clock, ONLY. Then bring the level up using the SMS's rear pad control to taste. YMMV but my experience is that anything over 10 o'clock on the SMS's front panel output control will overdrive the RV300


Very useful info, I'll try this out.

1. flipping on the bright switch
2. drop your bass to 0
3. start with your treble on 8
4. bring up your mids for your needed low end
5. adjust treble for clarity
6. turn up the volume!


Also useful, will try these and see.

The best sound I got (and it was very good) was with the same settings as you are using on the SMS but on the V300 I'd use 0 for reactance and 3 0r 4 for definition.


I'll try this. Good info from all, thanks very much for sharing! Will report back when I've tried it all out. 8)
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Re: Power amps!

Postby Jon S. » Tue Apr 24, 2012 2:30 pm

I'm thinking I'm becoming dyslexic. Yes, 10 o'clock for reactance (I'm actually down to 9 now) and around 3 on definition. Sorry for being so burnt out today! :oops:
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