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Update on the EP-600:

After talking to both JC & Brent over the weekend, I took apart the woofer today and checked for anything loose inside. Nothing found... I then tightened the hex screws around the amp which seems thus far to have silenced the rattle coming from the back of the sub. (great news)

After doing both, I didn't have a lot of time to experiment, but from a quick review of U571, it appears that the audible rattles during extremely loud/low bass is gone.

At this point, I am focusing more on placement and receiver configuration to see if I can dial into a sound on music that I like. I did listen to the Mugzy's Move CD for a few minutes and was very happy with the performance of the 600. This music is really not in my most-listened to genres, but I feel it really shows the full range of the Axioms and was very happy with what the 600 added to the performance.

I've also been playing a bit with the Buckcherry CD that Mojo and I were discussing in thread about the new SVS sub and have been working on tweaking the crossover and other receiver settings to see how close I can get to reproducing the ever-elusive "punch" we've been seeking. Given all the time Mojo has spent on this and all of the previous discussion about how what I think I want is actually described as sub-par performance from a sub, I don't expect to find what I'm looking for, but I don't see any reason that it should keep me from trying!

The biggest change for the positive so far is the removal of the rattles that were really distracting me from any critical listening. Secondly, I've moved it around to different areas of the room and did another round of "the subwoofer crawl" to make sure I hadn't overlooked a better opportunity for placement. I actually did find a spot I like better for both sound and aesthetics (front left of the room, moved from the back right). The earthquake sub now sits in the back right where the 600 was, which seems to have smoothed response in the room a bit as well (though the issues with daisy chaining it through the 600 unfortunately remain).

JC and I are scheduled to talk tomorrow about the input impedance questions. He was going to talk to Ian & Tom to see if he could get some definitive info back to me about what's going on and if there is a way to overcome it.

I'm hoping to take the next week to spend some quality time with a variety of musical material to get to know the 600 and its performance with different genres of music. As you can probably tell by the tone of the note, I'm feeling a bit more positive about the 600 after fixing the rattles and moving to a new location. Now I can really take it for a test drive, which should be fun. (as soon as my ears stop rattling from the U571 test run tonight that is)

PS: I need to point out that what appeared to be a non-response from Axiom to my first set of e-mails on this issue was my fault, or rather, Yahoo's fault. Their spam filters were grabbing all of JC's e-mails back to me and not letting them through (despite him diligently resending them to me 3x over the course of a week!)

Of course, as soon as I called and left a message this weekend, JC called me back within 10 minutes and got me on the right track and figured out what was going on with the e-mail situation. JC/Brent, sorry about the confusion and thanks for all the help you've provided already!

Do you think and ep600 will work with an ep500 or is the impedance issue going to cause a problem?

It's going to cause a problem unless you have a pre/pro that has a high current output for the LFE. You need to get the input impedance specifics from Axiom and then find a pre/pro to match.

A couple of years ago I was driving a quad of EP500s/600s with an Arcam avp300 receiver, an older HK avr and later with an Arcam avr700. If you can't drive multiple subs the fault lies with your receiver/processor.

Are you sure the quads were being driven to their full potential?

In another post, I calculated the input impedance of the 600 to be 43% of the output impedance of the pre/pro. I found out later that the output impedance of my Denon is 10K. That puts the 600 at 4.3K. If you had 4 connected, that's an input impedance of 1K.

Do pre/pros out there drive loads as low as this? Maybe JohnK can jump in here who knows more about system specs than I ever hope to know.

Yes. I had no problem calibrating them or hitting 130db in room. The Arcams are high current units. Many receivers are just not designed to handle multiple subs let alone 7.1 setups. If your receiver can't handle multiple subs, time for a new avp and amp.

Hey guys,

"Punch" is a pretty subjective term, but it might help to think about what makes low freq in music and what it really sounds like in real life. Go hit the lowest key on a piano if you have one nearby or just think about what it sounds like. The fundamental note is 27.5 hz but it sounds radically different than a 27.5 sin wave. You are also hearing a whole bunch of harmonics. That fundamental low is there, if it was missing it would, well, be missing, but that is definitely not the whole picture. I play the bass guitar with my low string being B (31 hz). Believe me there is no punch when I thump that note. The string just moves too slow. The punch, if it is there, comes from timing with the kick drum such that it sounds like the kick drum hit my string. There is a ton of sound from the kick at around 45 hz. I think that is primarily what the bouncing low riders have boosted to the moon. But is the impact of the kick drum at 45 hz? What is the freq of the pedal thing actually hitting the drum head (initial attack)? I bet its quite a bit higher. It is the boom boom that is lower.

I don't think that a big driver in an enormous cabinet is going to ever reproduce the initial attack of the kick, the sound of my finger on the string or the hammer way down at one end of the piano string. Nor should it necessarily. You have other drivers much more suited to those sounds and when your sub is integrated well with the speakers you will not ever hear it directly. You will just think that those M80s are slamming. Can't you feel it? LFE is felt more than heard but should be directly connected to what we are hearing in a way that it is part of it, not separated.

Jeb

Jeb,

Agreed. The inital attack is higher than 100Hz. Likely that initial attack is around 8 msec and maybe a little faster which puts the frequency at 120Hz or greater. I don't hear that attack with my Axiom system. And now that I have the SVS Ultra 13, I KNOW that the problem is not my room!

Mo, if you mentioned it before, I missed it, but how did you find that the output impedance of your Denon is 10K? That seems rather unlikely since, as we discussed before, typical receiver output impedances are in the hundreds of ohms with few if any significantly over 1000 ohms. As I'd mentioned, for example, Onkyo specifically stated the spec as 470 ohms. I also saw a lab test of a Denon receiver from a few years ago in which the output impedance of the preout measured 1000 ohms. Again, if the number is actually in this range, your measurements and calculation would put the EP600 input impedance in the area of a few hundred ohms, which would be far lower than any I ever heard of.

Any preout number from a few hundred to a thousand ohms would work well with amplifier input impedances which are typically 10K ohms or more(usually more), therefore satisfying that 10/1 ratio rule-of-thumb for good performance(and receivers typically have sub outputs with plenty of voltage). I'm still waiting to hear what the input impedance of the EP600 amp actually is.

Hang on...let me go check the manual.