Valve amps, how many watts?!?

[joescartwright]

Hi all,

 

I've been using a mesa walkabout for quite a while now and keep thinking of changing over to something all valve. I picked up one of the tiddly Ashdown 15 watt valve heads and really like the immediacy it has compared to solid state stuff that I'm used to, it's not the fullest sounding amp I've played, which seems to be the main criticism of this particular amp, but for home use it's great.

 

So... if paired with a small but efficient cab like a barefaced two10, how many watts would be likely to keep up with your standard functions bands without being massively distorted? Compressed and a bit saturated is lovely but I'm not looking for something that's always gainy if that is helpful.

 

I play all passive basses, mostly with flats, and don't use much in the way off effects other than the occasional fuzzy or overdriven sound.

 

Any advice would be much appreciated

 

Joe

[EliasMooseblaster]

Ashdown themselves would advise (have advised) against it, but I've managed plenty of small gigs with a Little Bastard 30 (since rebadged as the CTM-30) and a not-particularly-efficient 1x15. More recently, it's been paired with a far superior 2x12 and those 30 watts have gone even further. I can also reassure you that the LB30/CTM-30 has a much fuller, richer sound than the CTM-15, but I guess that's what doubling the wattage does for you!

Normally, to be on the safe side, I drive the 2x12 with a CTM-100, but then I'm playing with a loud drummer, and I have a lot of sonic space to fill as we only have one guitarist. So I think my advice would be to see if a 30W is loud enough for your needs, but be prepared to move to something a little bigger if necessary!

[joescartwright]

If I can get away with 100w that'd be great, something like the ctm-100 or a v4b, I don't know how much I like the idea of carrying an SVT around!!!

[wateroftyne]

The Handbox WB-100 sounds right up your alley.

You're welcome.

[fretmeister]

I had a Mesa 4:88 for a while.

 

265W IIRC

 

It was astonishingly loud.

[joescartwright]

26 minutes ago, wateroftyne said:

The Handbox WB-100 sounds right up your alley.

You're welcome.

I'd love to try one out, I'd thought about their other one, the R-400 or something?, but not seen this one. Bit sheepish about buying one without trying it though.

[thodrik]

Just my opinion, but the Mesa Walkabout behaves in a very similar manner to an all valve amp to the point that I think that my Walkabout sounds more like a traditional all valve amp than my Trace Elliot V6 which is an all valve amp. Not saying you won't find something that you prefer, but I would definitely not sell the Walkabout too hastily. The V6 is allegedly 400 watts though, so to get 'traditional valve amp break up' I have to run it at completely unusable volume levels.

If you are going to go the all valve route, 100 watts would be plenty. In terms of traditional mainstream companies, Fender, Ashdown and Ampeg do 100 watt tube amps. There is smaller Mesa valve amp as detailed above, but the cost will be astronomical. They will all deliver varying levels of heft.

[wateroftyne]

I shifted my dearly-loved Walkabout because I wanted a little more headroom and clearer mids - the Handbox R-400 is, IMO, a Walkabout Plus.

The WB-100 adds a different dimension. The Walkabout / R-400 is close, but there's nothing like a valve power stage.

[thodrik]

Sounds awesome, I would definitely try one.  

The lack of headroom on the Walkabout is actually one of the things I love about the amp. I will admit though it isn't the most articulate of amps in terms of mids, more of a 'old school thump' kind of sound. 

[joescartwright]

Yeah, the WA sounds great but the few times I've played all valve the feel has been notably different. The transients seem much more apparent in a way I've not experienced with solid state gear.

 

The WB-100 looks like a good option, the lack of controls is a definite plus for me, I'd be happy with just volume and gain! @wateroftyne What does that little switch on the right hand side do?

[Phil Starr]

I'd say the sweet spot for valve amps is around the 100W mark. Any more than that and they get pretty heavy, and expensive. you can get away with a little less power with a valve amp because you can drive them up to their limits and the resulting overload is quite pleasing rather than unpleasantly distorted. Remember valve watts and solid state watts are still watts though, there's no magic going on just nicer distortion. Even that Barefaced isn't mega efficient compared with the old speakers that used to be used with valve amps 98dB/W will give 118dB with a 100w amp. My 1x12 gives 121db with a 300W amp and is just capable of matching a drumkit. That leaves you 3dB down though I think you should be able to push an extra 3dB higher on average because it's a valve amp.

I suppose what I'm saying is it's very do-able but you won't have a lot to spare on a very loud stage. If you had a couple of 2x10's then you'd be sweet. Hope that helps

[VTypeV4]

I have happily gigged my Bassman 135 (probably ~100w really) with it's matching 2x15 load ed JBLs. Those old drivers are probably more efficient than some of the modern ones mentioned above. I also gigged my old 60w head with a Trace 4x10 and 1x15 many years back in a 10-piece soul outfit - that was a bit marginal but it was definitely did a great job. I don't have to compete with a 4x12" or a heavy handed drummer though so as ever - YMMV..

On the other hand, my 200w Trace V4 and pair of SWR 2x10" have never run out of steam with that combination.. Again - YMMV.

Best of luck with whatever you choose..😀

[joescartwright]

2 hours ago, Phil Starr said:

I'd say the sweet spot for valve amps is around the 100W mark. Any more than that and they get pretty heavy, and expensive. you can get away with a little less power with a valve amp because you can drive them up to their limits and the resulting overload is quite pleasing rather than unpleasantly distorted. Remember valve watts and solid state watts are still watts though, there's no magic going on just nicer distortion. Even that Barefaced isn't mega efficient compared with the old speakers that used to be used with valve amps 98dB/W will give 118dB with a 100w amp. My 1x12 gives 121db with a 300W amp and is just capable of matching a drumkit. That leaves you 3dB down though I think you should be able to push an extra 3dB higher on average because it's a valve amp.

I suppose what I'm saying is it's very do-able but you won't have a lot to spare on a very loud stage. If you had a couple of 2x10's then you'd be sweet. Hope that helps

What's the maths behind those numbers? (I'm intrigued not being critical)

[VTypeV4]

If the speaker spec says 98dB / 1w / 1 meter, this means that if you drive it with 1 watt and measure the sound pressure level at one meter from it, it should record 98dB.

But remember, Watts are a logarithmic scale so if we double the watts up to 2 then the same speaker should achieve 101, double them again to 4, we get 104 and so on..

The maths above will be:

dB = 10Log (P1 / P2)

dB = 10Log (100 / 1) - put the numbers in ie the two wattages we wish to compare

dB = 10Log 100 = 20 - twenty is the difference between the two expressed on a log scale

dB = 98 + 20 = 118 - add the log calculation to reference SPL and there's the answer

There's a simpler way also - every time you multiply the watts by 10 then the dB calculation goes up by ten so one watt to ten = 10dB and then the same again: 10 to 100 is another 10 dB but that only works for 10 log calculations..

Hope that helps..

[Phil Starr]

That's spot on.

 

To avoid having to dig the log tables out as a ready reckoner all you need to know is that 10x the watts is 10dB extra and 2x the watts is 3dB. You can then make a quick rough calculation by adding the extra dB's you get for the extra watts.

Sticking with the Barefaced 2x10 which gives 98dB for 1W and looking at something like a 400W amp. That's two lots of 10x power and then two lots of doubling (400 is 10x10x2x2) in dB's that's 10+10+3+3 or an extra 26dB, 124 in total with the Barefaced cab.

You can only just hear a 1dB change in level so calculating it to within a dB is usually good enough. A 300W amp is going to give between 1 and 2dB less 122-123db which is close enough for most purposes.

The other bit of the story is why it's important. A metre away from a drumkit the average sound level is  around 103dB. An audience makes an ambient noise level of 85dB or thereabouts so your quietest bass note needs to be at that level and your dynamic range (the difference between the quietest and loudest notes) will be about 40dB. You'll operate in a range of 80-120dB in most circumstances and if your system will do this without distorting you are going to be able to cope with most situations. When looking at bass systems I always look to beat 120dB as a target. With a valve amp you can crank it up 3dB and it will distort, in the example above the distortion kicks in at 118dB, but because its a valve amp you will only notice it as a bit of grit on the very loudest notes and a lower power amp amp will still deliver.

 

 

[mangotango]

Back in the days of The Noo Wave (OK, very late '70s), I played in a punky-reggae band with a remarkably loud drummer and got by on my Fender Bassman 50 Export and its matching 2 x 15" cab.
Best bass sound I've ever had, better than anything else before or since. I even amplified my double bass through it.
Eventually moved it on because I was convinced (wrongly) that I needed more wattage.  Mistake.

However, 40 years on from that, I'm way past carting a cab like that around any more. I will live with a lightweight bass rig that is rated at a stupid number of watts - and not knacker my spine.

Edited July 13, 2018 by mangotango
update

[itsmedunc]

I've got a Selmer 50w Treble n Bass head. I paired it with 2 Ashdown 4x8's (500w and 600w) and it nearly blew my bass clean off. Power in the extreme!

[wateroftyne]

22 hours ago, joescartwright said:

The WB-100 looks like a good option, the lack of controls is a definite plus for me, I'd be happy with just volume and gain! @wateroftyne What does that little switch on the right hand side do?

It’s does some magic feedback loop thing that I don’t understand the technicalities of. In a nutshell, quick changes between:

1. Bigger, thicker sound

2. ‘Normal’

3. Tighter, slap-friendly

 

[joescartwright]

@VTypeV4 @Phil Starr Thanks! So how would I calculate it with two two10 cabs?

 

@wateroftyne Sounds really great, love the sound clips you posted in the other thread. Let's see if Leszek is happy to send over a demo model ... 

 

Wish me luck!

[Phil Starr]

It's slightly complicated with two cabs because the impedance changes so you may, or may not draw more power from the amp. That's probably less of a problem with valve amps of course as the output transformer means they should be able to match to most common impedances.

For the same power doubling the cone area will give you an extra 3dB.  

That's how itsmedunc got such a good result from his Ashdown 4x8's I'm guessing here but  an 8" speaker is pretty efficient if it gives 92dB/W. Two would give you 95dB about the same as a reasonable 12" speaker. Four drivers would double again so 98dB/W and two cabs 101dB/W a 50W amp into this would give an extra 17dB That will give you 118dB the same as you might get from a Two10 and a 100W valve amp. 

Two Two10's with a 100W amp would give you 121dB, with a little overdrive/distortion that would be as loud as a 124dB solid state system in practice. Louder than almost all drums and more than enough to permanently damage your hearing.

At this stage I need to say something. Each 3db increase in level halves the time you should be exposed to noise. Anything above 85dB will damage your hearing permanently if you are exposed to it for too long. The 100dB levels we average on stage with a Rock band will start to damage your hearing in about 15mins without ear plugs. I have mild tinnitus.

https://www.noisehelp.com/noise-dose.html

[wateroftyne]

10 hours ago, joescartwright said:

 

@wateroftyne Sounds really great, love the sound clips you posted in the other thread. Let's see if Leszek is happy to send over a demo model ... 

 

Wish me luck!

Good luck. He's on holiday at the moment, I think..

[joescartwright]

Thanks all for the help. Despite being a thread about being loud I completely hate loud noises and use some pretty serious ear defence even for moderate volume levels.

[Bill Fitzmaurice]

6 hours ago, Phil Starr said:

Anything above 85dB will damage your hearing permanently if you are exposed to it for too long. The 100dB levels we average on stage with a Rock band will start to damage your hearing in about 15mins without ear plugs. I have mild tinnitus.

https://www.noisehelp.com/noise-dose.html

Those levels are totally wrong, because they're A-Weighted. A-Weighting should only be used in industrial applications. It's useless with respect to music, as it doesn't measure  bass. The primary power pass band with music is centered at 60-70Hz, which when measured with A-Weighting registers some 40dB lower than actual. You may safely add 20dB to those noise dose recommendations when the source is music measured with C or Z weighting. 

[Phil Starr]

Well Bill you might if you plan to play solo bass with all the treble rolled off, I suspect Joe intends to play with other musicians, noisy guitarists and such like. If he pushes the bass to those levels you can expect everyone else in the band to turn up to match him. That'll probably mean the band collectively are going to reach levels maybe 6dB above the sorts of levels we are describing. I'm talking about a capability of 40dB dynamic range with peaks of 120dB for each instrument. I don't think you are seriously suggesting safely going up to 160dB peaks. 

I've chosen to make a whole series of assumptions in my sound levels, without making it into a 101 acoustics paper I have tried to indicate which bits are factual and what my reasoning is based upon where I've made broad assumptions. I don't think they are anything more than one person's opinion offered as a guideline but they are based in real world experience. I'd absolutely say that a speaker capable of 120dB across a broad spectrum is going to match a drummer 90% of the time and one which will only do 117dB is likely to struggle at times in some bands. I'm trying to keep it simple too, there are so many variables.

The only point I was really making is that there is no point in just purchasing more and more sound output just because you can, and that there are hazards in extremely high sound levels. There comes a point where you are loud enough.

[2elliot]

Buy a CTM100 and a good pre amp. Job done. They are loud enough for most applications and sound gorgeous, the pre amp is required  because the eq on the amp is very limited... but the basic sound is lush. Loud... yes, very.