Posts Tagged ‘ultimate attenuator’

Ladies and Gentlemen! Welcome to the bout of the century! A truly momentous occasion in the vein of David versus Goliath! In the red corner we have a Goliath, the reigning King of Attenuators, the Ultimate Attenuator; self-proclaimed King of Transparency – Guaranteed! In the blue corner is the Aracom Power Rox PRX150-Pro, a virtual David, armed with only a transparency sling ! And here’s the opening bell!

The Ultimate Attenuator strikes first, tongue lolling, with bombastic claims of pure transparency. The agile Power Rox ducks, and moves away, its sling of true transparency whirring rapidly. Wait! It launches! It strikes the Ultimate Attenuator square in the head. It’s going down! Oh the humanity! Oh the humanity! The match was over before it was even begun!

I had the great opportunity this evening of testing the Aracom Power Rox and the Ultimate Attenuator in a head-to-head shootout to determine which was the most transparent attenuator. As you can tell from the somewhat facetious and fictitious pseudo-boxing match, you know who won: The Aracom Power Rox PRX150-Pro. Folks, it wasn’t even a contest. Even at the lowest attenuation levels, the Power Rox swept the floor with the Ultimate Attenuator!

My Test Procedures

Equipment: My test was conducted using a Replica JTM45 equipped with original Mustard Caps and a pair of  KT-66’s, into a 4 X 12 cabinet equipped with (2) Original 55Hz Greenbacks and (2) Custom Weber (75Hz) Greenbacks, with a ‘Gibson 57 Les Paul Historic Goldtop as my test guitar.

Clean Test

First, I started with the amp totally clean. I strummed a simple chord progression to get my base tone. Setting the Ultimate Attenuator at about half “volume,” I activated it. I immediately noticed a distinct loss in both highs and lows, as even at minimal attenuation, the bandwidth of my tone was severely narrowed. The full bottom-end and sparkly top-end of my clean tone were significantly reduced. The tone wasn’t that bad, mind you, but it certainly lacked the richness of my base tone – it sounded flat.

One thing that really bugged me was activating the UA, which required a strumming the guitar, then switching on the UA, as if the UA needed a signal to pass through it to even start working. What a pain! It’s amazing that users would even tolerate this.

I repeated the same test with the Power Rox, setting it at half attenuation on the 6-way switch. The result was a reduced volume, but no loss of bottom- or top-end at all.

Clean Test – Bedroom Mode

Same test as above with both attenuators. With the Ultimate Attenuator, can you say “tone sucker?” The tone was not at all pleasing! Even more narrow bandwidth, and non-existent dynamics. There was nothing even remotely good to like at this level with the UA. How the UA website can claim to be “the most transparent and safest tube amplifier attenuator on the market in the world. Guaranteed” is beyond me. Even my old Dr. Z Airbrake sounded better than the UA. So again, at this level, the Power Rox just kicked ass. Lower volume, but full retention of bandwidth and dynamics.

Dirty Tests

In my dirty tests, I ran the amp in its drive channel cranked up fully. 40 Watts through a 4 X 12 is LOUD!!! Especially when you’re standing right in front of the cab! Actually there’s nothing like feeling the SPL’s with an amp full-out! I ran the same tests as I did with the clean channel with both attenuators, and as expected got the same results: The Ultimate Attenuator really sucked my tone, while the PRX150-Pro retained tone and dynamics at all levels. The Plexi switch just made the tone even worse, acting like a treble booster, which made an already horrid tone even worse by just upping the highs. The tone was akin to an old transistor radio played at the volume of a loud TV. Not pleasing at all, and actually, it was a bit annoying, like cats screeching! YUCK!

The Power Rox, on the other hand, again just reduced the volume. The tone remained rich and full, and all the overtones and harmonics came through. It’s amazing what those subtleties do for your tone. You really miss them when they’re not there, as they provide depth.

It’s evident that the Power Rox’s Speaker Reactance Thru technology is far superior at any application. For me, the Ultimate Attenuator company can make all the claims it wants about transparency, but that’s all they are: claims. And while it doesn’t sound all that bad at low attenuation levels, the marked difference in tone between the UA and Power Rox at any attenuation level relegates the UA – at least to me – to the junk heap. You couldn’t get me to put this in my rig if you paid me.

I realize that the UA was the best game in town for quite awhile, and I am sure that at the time it came out, it outperformed the THD HotPlate, which I have also tested, and didn’t like. I also realize that I’m being fairly harsh – much more harsh than I’ve ever been with a product – but all the claims of the UA being truly transparent are mere exaggerations, and not backed up by any discussion of its technology. In fact, all the hyperbole surrounding the UA is quite irritating!

If you knew what went into a UA, you’d have serious concerns, not the least of which is the 32 ohm fixed resistor, which essentially flattens out your impedance, and creates a mismatch so high that you could fry your amp! Adding insult to injury, the solid-state amplifier is what is really running your speaker. Transparent? Hell no! Not electronically, and definitely not audibly.

And mind you, I’m not the only person who feels this way. One new PRX150-Pro user, who is also a former UA user was so impressed with the Power Rox and disgusted by the UA’s tone compared to the Power Rox, that he bought two Power Rox’s! That says quite a bit.

For more information about the Aracom Power Rox PRX150-Pro, visit the Aracom Amps PRX150-Pro product page!

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I can just imagine the heat from the flames I’d get on the forums if I said this, but this is something I just can’t hold back any longer after reading so many threads on the Ultimate Attenuator. I’ve spent a lot of time studying how different attenuators work, and I’ve come to the conclusion that despite its popularity, this is not an attenuator that I’d even consider getting, even if it’s at a reasonable price – which it isn’t. I have a lot of different reasons for not liking this attenuator, but the biggest issue to me is the fact that with the UA, the amp is no longer reacting with the speaker and vice-versa. The UA has a cheap, solid-state amplifier built into its circuitry to re-amplify the amp’s signal after it has passed through the 32 ohm fixed resistor. At that point, the speaker is interacting with the solid-state amp. How that can pass for transparency is beyond me.

Then there’s the fixed resistor. Don’t even think about running a 2 or 4 ohm output into that attenuator. You’re risking serious damage to your amp if you do that. The impedance mismatch there is so high, it has the potential to fry your power tubes or worse. As an add-on, you can get the 16/32 ohm switch, or get one of Ted Webber’s impedance matchers. But then you’ve already spent $750 – that’s just nuts!

I use the Dr. Z Airbrake which uses a rheostat type of resistor to provide variable attenuation. People have complained that at high attenuation levels it sucks tone. It does indeed, but for normal usage, just above loud conversation volume, it is very transparent, and I would daresay that it’s much more transparent than the UA because the amp and speaker are still reacting to each other as there is no “middle-man” solid-state re-amplifier.

I’m probably going to piss people off with this little rant, but so be it. I freely admit that I’m no electronics expert, but I do have the intelligence to understand a thing or two about amps, and a re-amplified attenuated signal – at least to me – isn’t going to be transparent.

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