getting more volume out of a tube amp

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Post by ??????? » Sat Oct 28, 2006 8:43 pm

riantide wrote:Man, I have a 45 watt amp and my bandmates are constantly screaming at me to turn the damn thing down.

Elevate it for sure, you'll be able to hear it better. But if you want it to actually BE LOUDER, you'll need to look into mods probably. If you have a tube rectifier, a solid state rectifier will increase your headroom. You also might want to look into having your amp biased for 6550's as opposed to 6L6's. Those tubes have different breakup characteristics and will stay cleaner a little louder. And they sound cool, they're a little more chimey than 6L6's. At that point you're looking at changing the sound of the amp considerably though, so you might want to hang onto it and get another - louder - amp for playing with the band.
Just be careful. In certain amps the B+ voltage will be raised too high with a solid-state rectifier, and you will start melting power tubes (and possibly transformers) in the process. The blackface Deluxe Reverb circuit is one of these.

Additionally, the 6550 requires more current from the 6.3v filament tap of the power transformer than does the 6L6 or 6V6. Be sure your transformer is beefy enough to handle it before you go putting 6550s in there. Fender was pretty good back in the BF days about over spec'ing transformers so they would probably be okay, but I wouldn't do it to my own amp, personally.

As always, be careful accepting strangers' advice on internet forums, mine included :lol:

riantide
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Post by riantide » Sun Oct 29, 2006 11:55 am

Agreed. And of course talk to a good tech about any mods you're considering. They know a lot more than we do.

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Post by GooberNumber9 » Sun Oct 29, 2006 6:23 pm

I second the notion of ignoring the wattage. It has very little to do with the apparent loudness of an amp.

I'd say the most important things are:
1) Speaker cabinet type - get a 4x12 that matches the nominal output impedance of the amp, and get one that is sensitive. Go to Guitar Center or whatever and ask them. (find the old guy)

2) Power Tube setup - Find out if the amp has adjustable bias. If it does, try biasing it colder so that you get more headroom. This is why low-power Mesa/Boogie amps sound so loud - they're biased way too cold (that and the custom speakers, see above). If the amp doesn't have adjustable bias, call Bob at Eurotubes (www.eurotubes.com) and tell him about your dilemma. Consider buying a whole set of tubes. The tubes he sells are some of the best 6L6es I've ever heard.

3) Overall signal clarity - Use as few pedals as possible. Don't put a lot of delay-based effects like reverb, chorus, etc. in the chain. The rig will probably be loudest with no pedals, a single-coil guitar, and the tone controls in the middle. If there's a presence control on the amp, crank it. If there's a focus control, crank that also.

Experiment!

Todd Wilcox

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Post by ??????? » Sun Oct 29, 2006 7:34 pm

Another thing to try: Try disconnecting your negative feedback loop.

those amps have a negative feedback loop aimed at increasing headroom, but you actually lose a little volume. It evens out the frequency response, dampens the speaker, and makes the transition into overdrive more sudden (less gradual).

Disconnecting the negative feedback loop is as easy as removing one wire. You can try it out and see if you like it. It hurts nothing in the amp, but will make it sound louder, rawer, more midrangey, more touch-sensitive and responsive to the speaker's variable load (you will feel that the speaker is connected to your fingers, if that makes any sense), and the transition into overdrive from clean is much more natural and organic, less sudden, etc.

If you like to have both, you can do a mod I did on my blackface Deluxe wherein you install a 3-prong grounded plug and disconnect the ground switch (this should've been done already anyway for safety) and re-route the negative feedback loop through the now-disconnected ground switch. Voila! Your 'ground' switch is now a 'negative feedback on/off' switch, or a "polite/rude" switch, or as I like to think of it, a "blues/jazz" switch for my personal uses.

If you'd like more details about this let me know, I can post it tomorrow. No time now. The mod is totally non-permanent and easy to put the amp back to 100% stock. If you halfway know what you're doing it takes about 10-15 minutes to route the NFB through the ground switch. You should only attempt it if comfortable working on amps/discharging caps etc. Good luck!

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Post by lg » Tue Oct 31, 2006 10:32 am

GooberNumber9 wrote:The rig will probably be loudest with no pedals, a single-coil guitar, and the tone controls in the middle.
hm, i've found in general humbuckers to be louder than single coils...

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Post by kayagum » Tue Oct 31, 2006 1:33 pm

Another thought. Are you plugging in directly to the amp, or do you have effect pedals?

Some boxes are notorious tone suckers (especially wah and volume pedals). Even a long instrument cable can suck, or worse get interference. Getting a box that lowers your impedance can help the clarity of the tone.

Three that I have used and worked for this:

ZVex SHO
VHT Valvulator
Maxon CP101 compressor
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Post by riantide » Tue Oct 31, 2006 5:14 pm

hm, i've found in general humbuckers to be louder than single coils...
They do have a higher output, but they hit the front end of the amp harder and cause it to break up sooner.

Pedals without true bypass might suck tone a bit, but they wouldn't effect volume that much, they would mainly just introduce more noise. And true bypass pedals shouldn't be too much of a concern; use as many of them as you want. But yeah, the difference between going straight in and using 9 boss pedals in a row will definitely be noticeable.

Also, biasing colder will give you more headroom, but it will also make the amp sound worse, in my opinion. Such is the case with most mesa amps. Again, that's just my ears, not yours. Last time I checked Bob at eurotubes.com deals JJ tubes, which are amazing for new tubes. I have those in my Super Reverb at the moment, I think. Those are great tubes, but a good NOS RCA Blackplate or a Tungsol 5881 would be even sweeter... (drool)

This is gonna seem kind of stupid, but I noticed that I was cutting through the band a whole lot better when I stopped scooping my mids several years ago. Now I have the mid knob on 10 on every amp I play. That's another matter of personal taste though...

Brad, I'm damn curious about the NFB mod. Thinking about trying that one...

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Post by ??????? » Tue Oct 31, 2006 5:48 pm

will post later when I have more time.

The short version is, there is a yellow wire coming from the board and connecting to the ext. speaker jack. Disconnect it at either end (easiest to get to at the speaker jack) and you have defeated the negative feedback loop. I route mine through the ground switch so it can be switched in or out.

As always, if you open your amp, make sure you know what you are doing and be very careful.

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