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[Timmy Liland]

I got this email from a friend.

I have a 60W Fender and a 15W Fender, all tube amps.
The volume button on the 60W (Hot Rod DeVille lll 212) is not very linear, I mostly use it between 1 and 2, the best sound can be found between ca 1.5 and 1.8.
This is still too much sound for my living room where I practice.
I therefore bought a 15W Blues Junior hoping that reducing the wattage would reduce the sound.
This is indeed an angry junior. Being so small it has an enormous SPL and an incredible sound. Although the volume button is a little more sensitive it is still too much for my living room.
After trying both amps at a gig I feel that the Blues Jr is as loud as my Hot Rod.

So my question is:
What is it that determines the SPL output from a tube amp?
Is it the number of tubes?
The tube type?
Loudspeaker sensitivity?
Is it possible to reduce the SPL in any Way
Other things?

[Chris Grimshaw]

Sounds like they've put most of the useful control in the first fraction of a turn. Bad design, IMO, but there you go. Helps with sales: "see how loud it is, and it's only on 2!". Sure, but it goes crunch at 3 and is technically on fire at 5.

If you want to reduce the volume, there's a couple of things you can do.

1 - Swap out the volume pot to something that acts in a way that's more useful.
2 - Put a -10dB attenuator in the FX loop.
3 - Put a power soak L-pad on the speaker output
4 - Try a lower sensitivity speaker in there

If you're feeling up to the task, #1 is the way I'd go. #2 will work and you can take it out for a 10dB boost, but I don't know if the amp has an FX loop. #3 is useful if you want to drive the amplifier harder (get that output stage saturation going) without increasing volume. Adding resistors can change the tone, though, since it'll interact with the speaker's impedance curve. #4 will definitely change the tone.

Chris

[TJ (Tom) Cornish]

I got this email from a friend.

I have a 60W Fender and a 15W Fender, all tube amps.
The volume button on the 60W (Hot Rod DeVille lll 212) is not very linear, I mostly use it between 1 and 2, the best sound can be found between ca 1.5 and 1.8.
This is still too much sound for my living room where I practice.
I therefore bought a 15W Blues Junior hoping that reducing the wattage would reduce the sound.
This is indeed an angry junior. Being so small it has an enormous SPL and an incredible sound. Although the volume button is a little more sensitive it is still too much for my living room.
After trying both amps at a gig I feel that the Blues Jr is as loud as my Hot Rod.

So my question is:
What is it that determines the SPL output from a tube amp?
Is it the number of tubes?
The tube type?
Loudspeaker sensitivity?
Is it possible to reduce the SPL in any Way
Other things?

Timmy,

As you have discovered, electric guitar amps are extremely efficient and can make a lot of noise with just a few watts.  All else equal, a 100 watt guitar amp will go louder than a 10 watt guitar amp, but that doesn't mean that a 10 watt guitar amp isn't also too loud.

Chris's suggestions cover much of the gamut, and all of them may have consequences to your tone to some degree. 

One other thing not yet mentioned is what is before the amp.  You may have too much gain in your pedals if you're using them.  See if you can reduce the gain somewhere before the amp and see if that helps.

[Noah D Mitchell]

Timmy,


I've been using a Weber MiniMass attenuator on my 22w 65 Deluxe Reverb re-issue - and I love it. You can dial in the amount of attenuation you need, and it has options for treble boost if you feel it's soaking your tone too much.


I found mine on Reverb.com for $80, but here's another one for a bit more...


$0.02

[Ivan Beaver]

The difference between 15 watts and 60 watts is 6dB.

About 2 clicks on your TV remote.

You need to think in terms of dB, NOT watts.

[Jay Barracato]

The difference between 15 watts and 60 watts is 6dB.

About 2 clicks on your TV remote.

You need to think in terms of dB, NOT watts.

I keep clicking the TV remote at my fender deluxe but it doesn't make a noticeable volume difference.

Seriously, an l-pad works nice for knocking the edge off, but I think there is a lot to be said for simulators in many playing situations especially if you are recreating classic tones.

Sent from my Moto Z (2) using Tapatalk

[Luke Geis]

So tube amps are unique in a couple ways. First and foremost, the type of tube and the topology of the amp determines its overall wattage output. What most don't realize is that a speakers output is rated at 1 watt @ 1 meter. So a 1 watt signal is sent to the speaker and output is measured at 1 meter. So when a speaker says it will do 98db at 1 watt / 1 meter, that means it will produce 98db with only 1 watt of signal. 98db is quite a bit really and the majority of guitar speakers will be right around 95db 1 watt / 1 meter. The other neat thing about tube amps is that they produce the same output wattage regardless of the ohm's of the speaker that is connected to it. If you plug a 4 ohm speaker into the 4 ohm output jack you get the same wattage as if you stuck a 16 ohm speaker in the 16 ohm jack. Solid state amps work differently and will drop wattage when higher loads are plugged in.

Another unique thing to tube amps is the way they compress when distorted. They don't clip per se like a solid state amp does, they just compress more. The THD is still high, but it is smoother and more rounded and the type of harmonics of the distortion that is created from clipping is generally more acceptable to the ear. This compression and more rounding off of the clipped signal gives the amp the perceived impression of more volume, even though the wattage is the same in comparison to solid state counterparts.

So when you have a 100 watt tube amp and you get it to the volume you like, there is a high likelihood, that you're only using a few possibly only 10's of watts. Each time you double the wattage you realize a 3db increase in speaker output. So if it is 97db 1 watt / 1 meter ( going for easy math here ), when you present 2 watt on teh speaker you will have 100db in output. If you go from 2 watts to 4 watts, you will have 103db of output. If you present 8 watts of output to the speaker you will have 106db of level from the speaker. So as you can see the majority of level from the amp is produced rather early. As you start turning up more, you are getting less and less actual output. The way the volumes work on many guitar amps lends to an altered impression of what the amp is actually doing. The fact is that even though the volume knob is at 1-2 or even only 5, the level sent to the power amp may be high enough to have already driven the amp to full output and it is simply starting to clip. This is why many amps don't seem to get much louder after a certain point, they just get more crunchy and distorted sounding.

So your little Blues Jr. is rated for 15 watts. If the speaker that is in the cab is rated at around 95db, it will be rather loud for bedroom practice and when cranked full nilly, could get as much as 107db. This is rather freaking loud when you are only a few feet away. If the speaker is even more sensitive, you could be well over 110db!!! So how much louder is a 100 watt tube amp then? Well in theory, with the same speaker, it would only get about another 6-8db louder. Not much, but enough to be perceived as perhaps twice as loud.

The quick and dirty way to gain more control over the touchy master volume is to insert a volume pedal or other type of devise with volume control into the FX loop. This will allow you to dial down the level to a more usable range at the cost of some extra noise.

[Ned Ward]

Chris nailed the right answer, and here's the background.

Fender for some dumb reason put a linear taper pot in these Deville amps instead of a more common audio taper pot. It's involved in terms of the soldering, but any amp tech worth his or her salt should be able to do this easily and give back more range on your volume knobs and make this amp useable again.

the Blues Jr. is a loud angry little amp - it's loud because it's EL84 powered, and 2 x EL84 can get deceivingly loud quickly. It's also why it doesn't sound like other Fender amps because outside of the Champ/Princeton/Deluxe that run 6V6, the bigger brethren all run 6L6 tubes.

Changing the speaker to a less efficient one can help, but those Blues Jr.'s are just fun little loud amps. Run it through an extension cab for a treat.

Here's the Seymour Duncan article on this.
https://www.seymourduncan.com/forum/showthread.php?188708-Hotrod-Deluxe-Volume-Mod

[Stephen Kirby]

Changing the pot is best done by someone used to working on PC boards.  Old school amp techs don't like them because they've never learned how.

After playing with various attenuators, I like a plain old L-Pad.  Especially on a small amp that doesn't have that much power.  My rebuilt Deluxe Reverb with Vibrolux transformers but still with 6V6s puts out 28 W at clipping.  Which a 100W L-Pad can handle easily.

Lower efficiency speakers are also a good way to attenuate the amp a bit.  Derek Trucks used to put comparatively low efficiency car stereo speakers in his Fender amps to allow him to drive them harder.  The guy who developed the speaker in the Hot Rod Deluxe told me that his marching orders were to make the amp sound as loud as possible.  Odds are the folks on the DeVille and Junior probably were told the same thing.  Along with the linear taper pot to make the big initial jump.  You also get the opportunity to revoice the amp a bit.

And I did say clipping.  I determined this by looking at a scope and observing a 1kHz sine wave until the top started flattening and measuring the voltage at that point.  It flattens out with rounded edges and eventually harmonic components.  Much less ugly looking that the higher frequency ringing and sharp edges you typically get overdriving a transistor.  But clipping just the same.

EL84s were designed to shrink an EL34 pentode into something that could be put in a car radio (back when car radios had tubes) and other compact devices.  Dick Denney used the EL84 in the Vox AC15 (later doubled up in the AC30).  It fell out of favor as folks wanted higher and higher power amps but has had a resurgence as of late.  The Mesa Maverick uses 4 in a class A section and is probably the warmest sounding amp they've ever made (I've had one along with various Marks) so there's nothing intrinsically bright, jangly or raw about them.  It's just how the circuit is designed.  It was also used in the Watkins Dominator which has a very unique sound (think the guitar solo at the end of the Abbey Road medley or various Led Zeppelin songs).

[Luke Geis]

I recently built ( from scratch ) an 18 Watt Marshall TMB variant! It has more balls than most amps and has a pretty neutered coupling cap between the first stage and the cathode follower on the high gain channel. The clean channel as far as I am concerned is the loudest clean channel I have come across! It also get s very loud very quick.

Do not be fooled by low wattage amps. If you plug them into the same cabs as you do your bigger amps, they sound just the same if not ballsier. If you want bedroom quiet, you really have to get the current run of modelers. The AX8, Helix, POD HD and teh like are getting so close.

[ProSoundWeb Community]