Yes indeed, it should be much the same. In theory a tad more high treble but unlikely to be noticed or easily adjusted for at the amp.@JohnH ,
Has it ever been determined whether or not the 8 ohm M2 is as friendly to a 4 ohm load as the 16 ohm version is to an 8 ohm load?
Just Curious?
Gene
Hi @Lancer X , dB numbers are ratios expressed on a log scsle. So anytime you halve the power, that's -3db. 1/4 power is -6db. 1/10th power is -10db. Our first stage is -7db so that's 1/5th power. etc
At 2W from the amp, there's really not much power. So I think any sensible mounting will be fine.
For your building into the amp chassis, which I haven't tried, I'd watch out for placement of parts particularly the coil. Maybe test before committing. The coil may produce a tendency to induce signals into any input wiring nearby, particularly on its axis. And mount it with a spacer to the chassis, using non-ferrous bolts of other means such a zip ties.
Hi @Lancer X , welcome to our world!
Yes you can scale down the power rating of the resistors. For a nominally 50W amp, R1 is spec'ed at 100W rating, ie 2x the amp power. It takes about 30% of the power of the amp, which gives is a factor of x3 for a case-mounted resistor. You might chose to try the ceramic block resistors, for which Id give a bigger factor. say 5. 2W x 30% x 5 = 3W. So you could go 5W or 10W.
@Lancer X ,
Next> I strongly recommend that you build the full blown, full wattage version of the M2. Once you plug your "full sized" 5E3 into the M2, your Weber MiniMass will collect dust!
A Hammond 1590D will work well, but @JohnH prefers the slightly larger 1550G. These are the fairly thick die cast boxes, not the thin aluminum sheet metal units! I implore you to build it as a well ventilated tank and you will never have a problem!
Just Sayin'
Gene
Yes indeed, it should be much the same. In theory a tad more high treble but unlikely to be noticed or easily adjusted for at the amp.
So an 8 Ohm M2 with all the Outs, is good for 16, 2x16, 8, 2x8 and 4 Ohm cabs.
-3 dB is half the power (1/2), -6 dB one quarter (1/4 = 1/2 * 1/2), etc.Here's a maths puzzle, for anyone to try: If BB is running his 50W amp, at the max attenuation of -31.5db, plus the added -28db stage, how many Watts are reaching the speaker?
Thanks for posting that. Yes it is interesting. I think I've seen something from that study before, though not that page.@JohnH , @Gene Ballzz , and crew:
Here's a link to an interesting post about placement and orientation of a pair of air core induction coils versus its effect on measured inductance. Likewise, they discuss placement close to 15mm thick aluminum panels, which seems to have a major effect on inductance.
Now of course you guys have been building in ~2mm thick Al enclosures all along, and you're happy with the curves that your attenuator designs are generating, so this is largely academic. Thought it might be helpful for future designs though, since you're probably not getting the exact inductance value that you planned for the circuit.
Cheers!
@Lancer X ,
What is that amp, anyway? Cool color for the Tweed!