mass attenuator

[Bushbaby]

Hi all 
I do hope you've all had a good Christmas and are staying very safe.

After all the years of playing guitar at home I finally decided to buy a mass attenuator so that I could play at a reasonable volume (to me) without annoying anyone (as much as possible). I bought a Harley Benton PA100 attenuator having read numerous reviews but I am just a little concerned about the Lpad. I have noted that these appear to damage relatively easily if pushed too hard. Considering that that the biggest amp that this will be used with will be 20 Watt output, is this something to be too concerned about? I do have to say that I haven't used it yet either!
I am not planning to use this on any bigger amps such as my 150watt Trace Elliot GP7 SM150 which works a treat at an output level of 1!

Best Regards

Rob

[Amie]

It will be fine on 20W Rob!

Another way to do it is lower the HT of your amplifier, or easier and cheaper still is use a smaller amp and overdrive that!

Seasons greetings.
Amie.

[Murphyv310]

Hi
I made an attenuator for valve guitar amp repairs many years ago.
In the workshop I used a dummy load mostly but the band boys wanted to hear the amp fully cranked up on collection.
There was no way I could allow this as the Audio Dept was directly above the main office.
So I made up the box with various load resistors and dropping resistors to the speakers. Only had to buy a die-cast box, all the resistors were made up from TV droppers, worked a treat, most likely in the loft somewhere.

[Bushbaby]

Thanks
I bought a small amp years ago from Matamp in Huddersfield (Little Rock) to have something of low power (4 watts) to drive hard at home. However, this was so far from the truth as its a truly LOUD amp and is far too much for bedroom use.
One day, I will get around to building a part isolation cabinet to see if this helps. I've always wanted a custom built music room at home but I just dont have the space and I now think its unlikely we will move again coming to the end of my working career.

Best Regards

[Crackle]

I made a 10:1 power soak for my sons Marshall JCM800 Super Lead amp, so that he could drive the amp hard at home.
It was a blessed relief.
Mike

[Mark Hennessy]

Of course, the difference between 20 watts and 4 watts is only 7dB...

Guitar speakers are very efficient. Picking one at random, the Celestion "Eight 15" - just picked at random as the smallest (8") guitar speaker on their website - the sensitivity is quoted at 95dB. That's an incomplete spec: what they really mean is 95dB, measured at 1 metre, with a 1 watt electrical input.

Just let that sink in for a moment. Just 1 watt will produce 95dB, relative to the threshold of hearing (20µPa). That is a seriously loud noise. From just 1 watt.

For comparison, good monitor loudspeakers might be 85dB/W/m. The LS3/5A is nearer 83dB. An efficient hi-fi speaker might be closer to 90dB/W/m.

This speaker has a power rating of 20W. That's 13dBW, meaning that one of these speakers fed from a 20W amp will peak at 108dB at 1m! Even a small 4W amp will make something like 101dB. That's ignoring second-order effects like power compression, breakup, etc...

Just out of interest, I noted that their 15" guitar speaker (the "G15V-100 Fullback") is 99dB/W/m. And it has a power rating of 100W, which is 20dBW, so one of these will make 119dB at 1m.

After the drummer, my biggest challenge when doing live sound is persuading the guitarist(s) to turn down their amps. If I'm aiming to keep the whole band below around 90dBSPL, you can see the problem... Don't forget that the guitars (and most of the other instruments and vocals) have to be piped to the stage monitors so the rest of the band can hear their colleagues more clearly. A lot of the time in our small venue, the PA is virtually just carrying the vocals and kick drum! Slight exaggeration, but you get the idea... Thank goodness for power soaks and modelling amps!

If building a power soak for home practice use, I'd instinctively expect to need more than 10:1, which is only 10dB of loss. Perhaps have an option for 100:1, giving 20dB? Obviously it depends on the power output of the amp in question and the speaker sensitivity, but having shared a student house with a guitarist using a 3W valve amp (found in a skip!), I know how loud these things can be in a small room!

[Murphyv310]

Hi.
Totally agree Mark.
In a very practical way I bore this out a few years ago.
I made a Mullard 3-3 as a test amp around 8 years ago.
It was something else before but it used an EL84 and ECC83. I converted it to the 3-3 but unfortunately it had to make do with 230v HT and a very small output transformer. It actually works OK but is restricted to 2 Watts before it clips like mad.
Fast forward to 4 years ago. I had a Marshall 100 watt amp to fix that no one else would fix. Once complete the owner said he'd bring the speaker to test it with.
Well the speaker took up a lot of room in the shed had a pair of 12 in drive unit's. The Marshall was loud to say the least, deafening at the annoyance of one neighbour even for just a minute. I then thought I'd try my 2watt 3-3. Again my neighbour complained, it too was loud at less than maximum it was very pleasant indeed, great quality and bass from that tiny output transformer. So yes an efficient speaker can make a big difference to what level you hear.