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Discussion in 'Marshall Amps' started by DreamerDeceiver, Dec 5, 2021.
Oh, I know, just havin' a little fun, too tempting.
According to my meter with 6db attenuator reduction average of 104-108db.
No, power brake is ok but a Rockcrusher is way better, trust me it's what i use with my 87X and there is one more in the room too.
I find that hard to believe. A single speaker is 100dB per Watt. If you play a 4x12 that figure rises due to acoustic impedance coupling for frequencies with wavelength longer that the distance between the speakers; say 103dB per Watt You then pump atleast 70 Watts in them. That is an extra 17dB . Total makes 120dB and this is in open space. In a closed room add atleast 6dB for 126 total. Shave off 6dB with an attenuator and you are left with 120dB.
That is high enough for permanent hearing damage after a single hour of exposure.
12 x 18 room with sound meter pointed directly at speaker cab will peak hold at the numbers i gave. Consistently every time. Maybe it's where i set the volume knobs?????
Neh. Once the PA overdrives it doesnt get much louder.
dBA,B,C, or unweigthed? What averaging time? Distance? Callibrated meter, which class? Do you have a callibration device?
Maybe you aet your attenuator at something else than -6dB? Something is significantly off for you to read those numbers.
To answer one of your earlier questions, the 1987X is made in UK. It's very well built. It seems like you're leaning towards the 1987X and IMO, is the right choice. I haven't built one of John H's attenuators yet but I only hear great things about them from those who have. You might also consider is a Fryette PS1, 2, or 100, as they afford options, not the least of which is a great "post" preamp and power section effects loop. Expensive, yes, but it will serve you well for your subsequent, several plexi purchases.
Rockcrusher fan and owner here..
My recommendation as well.
Nothin wrong with a THD attenuator , been using one for years .....with 1987's ,go figure
Nothin wrong with a PPIMV either
I like the PPIMV
Well if he is getting his attenuator at mates rates and as a pay when u can thing, I guess try what he will part with and find what your happy with and what lvl you can play it at, and that will mean more than any suggestion here
It can always be upgraded later.
My new les paul standard and EH power tubes really made the sound come around
The purchase is on hold:
Money constraints. Even though he offered to front it to me, Id prefer to have some dough on hand at the transaction.
We'll revisit in Jan 2022 .
Great info guys......plus, it gave me time to research what components to obtain.
Works best with guitar and guitar lead!
Speaker dB rating is on axis at 1meter. Also the lad never said his amp was cranked. Also +3 dB for two speakers, +6 for four. Also in a room a guitar speaker lands somewhere between a point source and line source. The most efficient frequencies at 1 meter on axis will occur around 4K or so so that is more on the line source side of things. Doesn’t drop as fast with distance but very directional. So where was the mic in this axis? We don’t know so 103 dB per watt even if known would be an improper assumption.
Get an SV20H (quite similar in operation & sounds to the 1987) and give it a MASTER VOLUME in the same part of the circuit as the SC20, by putting a JHS Little Black Amp Box in the EFFECTS LOOP. Gives the the best of both worlds. The 4-hole SV20H preamp, with the MASTER VOLUME of the SC20H!
We have a winner ladies and gentlemen.
Same on thd
Works well with all marshalls