Entry level Velo experiment

Lowell_M

I had my ADCOM GFA-555 disconnected from my 2-channel to demo a Marsh A200s (thanks dkg999) and thought I'd mess around with the ADCOM in my HT a little.

I've wondered for some time, but been to lazy, how the addition of a quality amplifier to my Velodyne CHT-12 sub instead of using the velo's internal amp might effect the subs performance. So, I connected the ADCOM in all of its gargantuan bridged glory. (hell, the ADCOM is half the size of the entire sub) I know that others have used the GFA-555's with some of the unpowered SVS tubes and have been very happy, but this test is different. Can an entry level sub sound good or even great with amplification better than the cheesy little plate amp that it came with?

The short answer is, "WOW YES!"

The longer answer is... The dynamics and overall output of the sub increase dramatically. I used the Transformers movie as my reference and was feeling things I didn't even hear before. And it wasn't just a gain issue. I had it somewhat calibrated so that output would be where it should, but the sub was able to keep up with some of the dynamic peaks that it couldn't before.

The driver never sounded like it was being strained. In fact, I turned the gain up a bit to see what happened and response was huge without any bottoming out. (I didn't want to go too far of course though)

The bad news... You are still working with an entry level driver in an entry level box. Port noise was an even bigger issue than before because there was more air moving. Response tightened up but still not near what I have heard in some of the SVS's and other higher end subs.

So, if you have a spare ADCOM GFA_555 sitting around and a low end Velodyne, by all means, use it as your sub amp. Is buying an amp like the GFA-555 a good upgrade solution for your entry level amp? Nope. Your money would be better spent on a sub designed to perform better.

Sure was a fine experiment though. My basement has never experienced such pressurization.

ben62670

I used my 555 to power my Titanic MKIII 15" Sono, and loved it. I broke the cone loose from the driver in chapter 13 of WOW. It kinda snuck up on me:o

ViperZ

How exactly did you connect 555 to the driver?

Wouldn't you need at least a cross-over in-between, since the amplifier amplifies the entire frequency range?

Lowell_M

I disconnected the IC from the LFE input on the sub and connected it to the mono input on the ADCOM. Then ran speaker wire from the ADCOM to the speaker level inputs on the Velodyne. The signal is already crossed over from my AVR, but there is also a crossover on the Velodyne.

comfortablycurt

ben62670 wrote: »

I used my 555 to power my Titanic MKIII 15" Sono, and loved it. I broke the cone loose from the driver in chapter 13 of WOW. It kinda snuck up on me:o

Is that one of the kit subs from Parts Express? How do you like that? I've been looking at them, and they look pretty nice. I was considering maybe checking one of those out instead of the SVS PB10 I've been looking at. It'd cost roughly the same, and looks like it might pack a lot more punch. The cone breaking loose isn't really a good sign though.

Sounds like a fun little experiment. Maybe I should get an Adcom 555 to power my **** little Pioneer 8" sub...lol...it'd pack a bit more punch than the 50 watt onboard amp I'm sure...probably also blow the woofer in the process though...

Lowell_M

heh heh... I guess my Velo isn't as entry level as I make it sound, but it's nothing compared to the SVS's out there. It's got a 12" driver and ... i think something like a 150watt amp. I used to think it kicked ****, but after hearing the MicroPro 2000 and some SVS's .... I realize its just ok. Much better than your average HTIB.

heiney9

R u home? We gotta get going!!

ben62670

comfortablycurt wrote: »

Is that one of the kit subs from Parts Express? How do you like that? I've been looking at them, and they look pretty nice. I was considering maybe checking one of those out instead of the SVS PB10 I've been looking at. It'd cost roughly the same, and looks like it might pack a lot more punch. The cone breaking loose isn't really a good sign though.

Sounds like a fun little experiment. Maybe I should get an Adcom 555 to power my **** little Pioneer 8" sub...lol...it'd pack a bit more punch than the 50 watt onboard amp I'm sure...probably also blow the woofer in the process though...

http://www.polkaudio.com/forums/showthread.php?t=51533
When it broke I had the tube volume at 9' cubed. This brought the power handling down to 500 or so watts. I shrank the enclosure to about 5' cubed, for better power handling, but it was better to feed it less watts in a bigger tube. As for the woofer breaking I think it was an isolated incident. Sub bass with a little too much power.
Ben

Systems

a_mattison wrote: »

Then ran speaker wire from the ADCOM to the speaker level inputs on the Velodyne.

But then wouldn't the output of the Adcom just be driving the Velo's internal amp ,albeit through dropping resistors to bring it down to a useable level?

ben62670

I am hoping he meant he hooked the amp up directly to the driver

Systems

ben62670 wrote: »

I am hoping he meant he hooked the amp up directly to the driver

That would be the way to do it,but his actual wording is "speaker level inputs".

Lowell_M

I am such a jack ****. I thought the speaker level inputs were passive right to the driver. So, now I'm not sure what the hell I accomplished with this little experiment.

My audiophile membership card should be revoked. At least my amp has 200 wpc even if I can't use it right.

Lowell_M

heiney9 wrote: »

R u home? We gotta get going!!

I made it there didn't I?!

Systems

a_mattison wrote: »

So, now I'm not sure what the hell I accomplished with this little experiment.

I guess if you didn't recalibrate the subs level when you hooked up the Adcom,the actual levels may having been somewhat higher thus giving the impression of greater output and dynamics etc.

heiney9

a_mattison wrote: »

I made it there didn't I?!

Yep, too bad you lost your membership card. Had I known..................I would have ripped it up in front of you!!!!

Sorry the band wasn't playing tonight.

daboyz

Band? What band?;)

comfortablycurt

ben62670 wrote: »

http://www.polkaudio.com/forums/showthread.php?t=51533
When it broke I had the tube volume at 9' cubed. This brought the power handling down to 500 or so watts. I shrank the enclosure to about 5' cubed, for better power handling, but it was better to feed it less watts in a bigger tube. As for the woofer breaking I think it was an isolated incident. Sub bass with a little too much power.
Ben

Wow...I think I might want to try building one of these. Sounds like a badass sub. You may be getting some messages from me looking for help on this in the future.