Axiom Home Page Forums General Discussion Stereo ADA-1500: A BEAST of an amp!

I reported a while back I flipped a couple of M5s on top of each other and connected them in parallel. In my room, this sounded very good - better than the M100v4. I found the images created on some songs unnaturally large though so I experimented a little by moving them further apart and adding spacers (port plugs) between the cabinets. What do you know? They sound great! See link.

https://drive.google.com/open?id=1-HTUof-ixrhav2AVhY0gi980WgAU2ZkR

I'm feeding them from an ADA-1500 and sitting 13 feet away. I can push them to 1350 peak Watts each...maybe more because I'm not sure I'm really capturing the peaks. This is at around +3 on my Onk. Even though the M5s are crossed at 80Hz to my 800v4, on bass-heavy songs the 1500/M5 combo gives in before my ears do on some well-recorded tunes. The songs that are shutting them down have some nice peaks in between some "quiescent" periods. These songs are "Drums of Thunderdome" by Estrella Boyer, the vintage version of St. Louis Blues by Wycliffe Gordon and a few others that are of similar acoustic signature. On Wycliffe Gordon, I can push each M5 to 1500W peak...LOL!

I'm surprised by how much power is really needed to get a visceral sense of well-recorded music. On these tunes, I could have used more power - a lot more. As I've said before, movies are a completely different story. I don't need an ADA and the Onk is just fine on BluRays at around -15.

Still, the ADA-1500 is a BEAST! Those M5s in parallel represent a load of around 3 Ohms which is a full Ohm below the rated load impedance of the 1500. That's 1300W to 1500W peak into 3 Ohms. That's 21 Amps of peak current into each pair of M5s!

If I replace the M5s with M100s, the ADA-1500 sources 2800W peak and the SPL is so high, I just can't take it even at 13 feet away.

I'm really looking forward to checking out the active M5s.

I should also mention those M5s swallowed that power like a champ. They sounded totally composed.

Nice. Now all you need is a pair of M5's as a center channel

Aye. A single M5 as a centre does sound puny.

Wow nice set up.

It's totally surprising how fast power demands actually go up. For minimal increases in volumes. We're told by so many oh 50 to a 100 Watts is ample. Heck even a tube is enough for some. Then we get in to party mode and realize that was only enough for background listening.

Looks like a fun weekend stacking and experimenting

Yeah...when it comes to music, 50W or 100W is not good enough for speakers of typical sensitivity. It might be good enough for something like La Scalas but they have other problems.

Hi Mojo

Did you get a reading on an SPL meter while blowing mega watts through your M5s?

Phil, my reference song for gauging peaks cleanly is Renee Olstead's Hit the Road Jack.

With that tune, four M5s in twin-parallel configuration as described above, crossed at 80Hz to my 800v4, I measure 111.5 dBC peaks at 13 feet away in my 4,200 cu. ft. room before the ADA-1500 throws in the towel.

In 5.1 PLII music, with the 160v4 powered by the third channel of the ADA-1500 and 2xQS10 powered by the Onk, I measure 112 clean dB.

This may sound like it's loud, and it is, but it's not ridiculous due to the nature of the song. I'd love to hear those peaks at 120dB.

Anyone reading this, I highlight the following: 111.5 clean dBC at 13 feet away, with amazing fidelity and holographic soundstage, for under $US7K! If I was the competition, I'd be quaking in my boots.

If you read some of my other posts, you come to the realization that twin M5s per channel with an ADA-1500 have 11.5 dBC more output than single M5s per channel with an ADA-1000. 3dB of this 11.5dB comes from stacking the M5s. The remaining 8.5dB comes from replacing the 1000 with a 1500.

A bit of that might come from wiring the M5's in parallel and so presenting a lower impedence to the amp... but I don't remember offhand what a single M5 is rated at impedence-wise.

A single M5 hits a valley of 6 Ohms at the low frequencies where I witness the 1500 and 1000 shutting down. Two in parallel go down to 3 Ohms at those low frequencies and 2 Ohms in the lower mid-range. That's well below the ADA 4 Ohm spec.

The saving grace for the ADA is that at low frequencies, the M5 load is almost purely resistive. That's not the case in the lower mid-range but there's less energy in that band compared to the lows so no shut-downs there.

Agreed that shunting boosts the current to a point. Then the voltage collapses and that's the end of that.

The ADAs are well-designed from what I can see.

I really love the protection on these ADA amps. Before they can distort or worse (ignite or pop a component), the channel in distress gracefully temporarily shuts down. When I say temporarily, I mean transiently. It's not like it turns off and takes minutes or even seconds to come back again. Sometimes the protection is silent, and sometimes I can hear a slight pop. I suppose there's a turn-off transient somewhere that arises in the circuit. That's not a big deal; it's just an observation.