# AudioControl Epicenter vs RCA Bass Detonator



## envisionelec

So you've probably seen these "bass processors" pop up over the years touting themselves as "like the Epicenter" with reps from AudioControl vigorously denying these claims.

So let's blow the lid off this thing. After all, that's what I do!

I purchased an RCA RC779D Bass Detonator on eBay on an educated whim that the physical appearance of the unit was quite similar to the Epicenter. I searched the interwebz for this unit and came up virtually empty-handed. 
My suspicions grew as the units were being unloaded as a "Turntable Bass Restoration" device when there is absolutely no 'phono' input, it is 12V powered and there is a "Dash Remote" port on the main unit. _Turntable Restoration...riiiight._

I received the unit today and opened it up to investigate. I was _shocked. _Let's look at the differences, the similarities and the errors.
A= Epicenter
B= RCA Clone

*1A*: Programmable Filter Module. A resistor network consisting of 8 same-value resistors that set the corner frequency of the subsonic filter. Default is 33Hz made from eight 220 ohm resistors.
*1B*: There are 8 resistors permanently soldered to the PCB. A person could/should replace these resistors with a 16-pin DIP socket to accept AudioControl's Filter Modules. It is set for 0.033Hz - basically defeated - because it is loaded with eight 220k resistors(!)

*2A*: Balanced/Unbalanced Input Selection
*2B*: Same jumper selections, but they're unlabeled on the PCB. Mentioned in the manual, though. Default, they have the input Balanced and the output Unbalanced.

*3A*: Adjustable voltage output via jumpers for 2.5V, 5V, 7.5V and 10V
*3B*: Same thing, except the 10V setting is obscured, making it look like 0V. Ha_ha_.

*4A*: Glowing Epicenter logo pulsates as the processor creates that rumble.
*4B*: The LED _locations are present, but not populated. _However, the rest of the parts _are_ installed so adding the LEDs is possible. But the lid is solid...so there's nowhere for the light to glow...er...go.
*
5A*: Epicenter power supply driven by a Linear Technology LT1072, a self-contained switching regulator.
*5B*: Contains a common TL494 and a single switching transistor. Functionally identical and much less expensive, though parts-count heavy.

*6A*: +/-15V Power Supply, regulated.
*6B*: Same.

*7A*: Remote Bass Gain control with two color LED (reverse it to change green/red) intensity increasing with clockwise rotation. Epicenter uses the LM13600 (obsolete) VCA IC for the remote gain. The 13600 has a documented DC offset problem that the superseded 13700 does not. 
*7B*: Very similar except only a Red LED. Uses the newer 13700. Audio Control may have switched to this - it is directly pin-compatible.

*8A*: ISO, 200 ohm and COM power supply isolation. This sets the ground reference of the processing circuitry to be fully connected, 200 ohms apart, or fully isolated from input ground connection. 
*8B*: The jumper doesn't exist. The secondary is connected to input GND through a 47 ohm resistor. 

*9A*: Top-mounted Red Power LED
*9B*: Top-mounted *********** LED AND front-firing Blue LED. They're connected in parallel.

*10A*: True Bass Reconstruction circuitry. The key component is a 4013 D Flip Flop which is used to generate a frequency 1/2 of the fundamental. 
*10B*: Exactly the same. 

So, let's look at some comparison pictures. The layout is absolutely identical. The only difference, as outlined above, is the power supply section on the right. 

Now, I have not measured actual performance of this clone, because I don't own an Epicenter. However, the circuitry outside of the power supply and the PFM hack is exactly the same: net-net.

If you are looking for a clone of the real Epicenter and _you are not afraid of some soldering _to fix that PFM issue_,_ then this is a STEAL at $19 shipped. Just look for it on eBay. A company called TechforLESS is closing them out.

Epicenter Clones - a set on Flickr


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## Miguel.Gto

thanks for taking the time to do the review... so what would need to be soldered ?


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## TrickyRicky

The 8 resistors to change the frequency.

Thanks for the comparing them. Exactly as I though.


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## tneig002

So basically it's a less luminescent Epicenter sans a subsonic filter?


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## envisionelec

tneig002 said:


> So basically it's a less luminescent Epicenter sans a subsonic filter?


You got it.  :surprised:  

I just hooked it up in my car - it works perfectly. 

I'll post a how to video on replacing the resistors soon - probably this weekend. It's very simple - you just need a 16 pin DIP socket and eight resistors...and basic soldering skilz. You can also use the official PFM modules if you wanted to, but they're just $1 resistor networks.

The formula for the resistors is (7200/frequency)= Resistor Value. So for 33Hz (standard) it's 7200/33 = 218. Use eight 220 ohm resistors.


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## Miguel.Gto

envisionelec said:


> You got it.  :surprised:
> 
> I just hooked it up in my car - it works perfectly.
> 
> I'll post a how to video on replacing the resistors soon - probably this weekend. It's very simple - you just need a 16 pin DIP socket and eight resistors...and basic soldering skilz. You can also use the official PFM modules if you wanted to, but they're just $1 resistor networks.
> 
> The formula for the resistors is (7200/frequency)= Resistor Value. So for 33Hz (standard) it's 7200/33 = 218. Use eight 220 ohm resistors.


thanks that would be very helpful, i bought one but haven't received it yet... how long did it take techforless to ship it ?


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## jason19

can you post a link to them on ebay I cant seem to find any


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## Miguel.Gto

jason19 said:


> can you post a link to them on ebay I cant seem to find any


they dont have anymore... they only had 1 new unit and 1 refurb, both sold.


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## Miguel.Gto

also, on your last picture where it has a page with the settings, it says 33hz filter factory, is that paper from epicenter ?? or came with the clone unit ???


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## envisionelec

Miguel.Gto said:


> also, on your last picture where it has a page with the settings, it says 33hz filter factory, is that paper from epicenter ?? or came with the clone unit ???


It's from the Clone. However it's totally wrong. 

The clone unit talks about changing the subsonic filter values - but doesn't say how. I think it's because you can't...

The clone's manual is very poorly written. It is an obvious copy of the Epicenter. 

But this isn't about the manual - the basic circuitry is the same...and that's all that matters.


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## envisionelec

Miguel.Gto said:


> thanks that would be very helpful, i bought one but haven't received it yet... how long did it take techforless to ship it ?


I wasn't paying attention...it was less than a week, though.


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## envisionelec

Miguel.Gto said:


> they dont have anymore... they only had 1 new unit and 1 refurb, both sold.


I don't know how legit these places are...but...

http://underbid.com/merchant/tflout...ator_Bass_Restoration_Processor.html?ref=base

http://www.electotronics.com/rcarc779dbassdetonator.aspx

http://www.d2delectronics.com/RCA-R...mponents/Turntables-Accessories-p5868372.html


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## Miguel.Gto

envisionelec said:


> I don't know how legit these places are...but...
> 
> RCA RC779D Turntable Bass Detonator Bass Restoration Processor, Electronics, Audio, Other at Underbid.com
> 
> RCA RC779D Bass Detonator
> 
> RCA RC779D Bass Detonator


i actually bought the new one from techforless_outlet on ebay.


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## Miguel.Gto

envisionelec said:


> It's from the Clone. However it's totally wrong.
> 
> The clone unit talks about changing the subsonic filter values - but doesn't say how. I think it's because you can't...
> 
> The clone's manual is very poorly written. It is an obvious copy of the Epicenter.
> 
> But this isn't about the manual - the basic circuitry is the same...and that's all that matters.


ok, so how do you know where the sweep is set at ???


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## envisionelec

Miguel.Gto said:


> ok, so how do you know where the sweep is set at ???


Read the Epicenter manual.


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## envisionelec

From further research, it seems that AudioControl has been slapped with a lawsuit on March 1, 2011 for falsely labeling their Epicenter products with an expired (as of July 11, 2005) 4,698,842 patent for Bass Restoration. HA!

The docket explains a Relator (private individual - possibly a whistleblower within AC) filed the complaint again AC via Patent Group, LLC and is seeking damages of up to $500 per falsely marked item. Not good!

And I JUST sent an email to the AC contact form advising them of this teardown/analysis. Not that they wouldn't know, but I was genuinely interested in the process of prosecuting the offending company. Now it appears I may have 'tripped the wire'. Oops. Hello, AudioControl peeps. 

Geez - the weird things you find while searching for other stuff. Here I thought I was going to find AudioControl suing someone else....

The internet rules for finding stuff. I am constantly amazed at the amount of information available online. 

Case# 2:2011cv00130 March 1, 2011


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## Miguel.Gto

envisionelec said:


> From further research, it seems that AudioControl has been slapped with a lawsuit on March 1, 2011 for falsely labeling their Epicenter products with an expired (as of July 11, 2005) patent for Bass Restoration. HA!
> 
> The docket explains a Relator (private individual - possibly a whistleblower within AC) filed the complaint again AC via Patent Group, LLC and is seeking damages of up to $500 per falsely marked item. Not good!
> 
> Geez - the weird things you find while searching for other stuff. Here I thought I was going to find AudioControl suing someone else....
> 
> The internet rules for finding stuff. I am constantly amazed at the amount of information available online.
> 
> Case# 2:2011cv00130 March 1, 2011


wow, interesting....

6 years with an expired patent !!!! lots of units


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## jrs1006

subscribed interesting stuff


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## tyroneshoes

The epicenter required a full range signal which many sub preouts do not offer, Im assuming the same requirement is needed for the RCA branded unit?

Interesting indeed


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## envisionelec

tyroneshoes said:


> The epicenter required a full range signal which many sub preouts do not offer, Im assuming the same requirement is needed for the RCA branded unit?
> 
> Interesting indeed


You got it.

If your Sub Preout crossover can be bypassed, then you can use it. Otherwise your results may not be as good.


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## Miguel.Gto

envisionelec said:


> You got it.
> 
> If your Sub Preout crossover can be bypassed, then you can use it. Otherwise your results may not be as good.


thats because it analyzes all the frequencies and creates bass frequencies based on the information. correct ??


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## envisionelec

Miguel.Gto said:


> thats because it analyzes all the frequencies and creates bass frequencies based on the information. correct ??


No - not ALL the frequencies. Just 200Hz and below. Its upper "creation" limit is ~100Hz.


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## envisionelec

Meh. I f***ed up the subsonic frequency calculation. It IS 220k, not 220 ohms. The RCA manual had a misprint. The values didn't make sense at the time - I should have known.

The correct method of calculation is 7200 / frequency = value in KILO ohms. So, for 33Hz it is 7200 / 33 = 218k ohms or [common value] 220k

I'm gonna have to change that because I'm losing valuable subsonic information.


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## tyroneshoes

envisionelec said:


> Meh. I f***ed up the subsonic frequency calculation. It IS 220k, not 220 ohms. The RCA manual had a misprint. The values didn't make sense at the time - I should have known.
> 
> The correct method of calculation is 7200 / frequency = value in KILO ohms. So, for 33Hz it is 7200 / 33 = 218k ohms or [common value] 220k
> 
> I'm gonna have to change that because I'm losing valuable subsonic information.


Im looking at an audiocontrol chip, it seems they use 8 pins for 24db slopes and 7 pins for 18 db. Can you confirm this?

Also if you have a chance envisionelec, I curious what your feedback would be on this post

http://www.diymobileaudio.com/forum...ssovers/104541-amp-gurus-i-have-question.html


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## Miguel.Gto

envisionelec said:


> Meh. I f***ed up the subsonic frequency calculation. It IS 220k, not 220 ohms. The RCA manual had a misprint. The values didn't make sense at the time - I should have known.
> 
> The correct method of calculation is 7200 / frequency = value in KILO ohms. So, for 33Hz it is 7200 / 33 = 218k ohms or [common value] 220k
> 
> I'm gonna have to change that because I'm losing valuable subsonic information.


how low would u want ur filter at ??? my subs have frequency response down to 25hz


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## envisionelec

tyroneshoes said:


> Im looking at an audiocontrol chip, it seems they use 8 pins for 24db slopes and 7 pins for 18 db. Can you confirm this?
> 
> Also if you have a chance envisionelec, I curious what your feedback would be on this post
> 
> http://www.diymobileaudio.com/forum...ssovers/104541-amp-gurus-i-have-question.html


Yes, that's correct. And an interesting but useless point is that they only use 6 of the 7 resistors on the 18db/oc.


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## DiMora

Or, for an another viewpoint - how about those of us that want bass restoration buy genuine AudioControl Epicenters that are made in Washington state and support some American jobs instead of Chinese knock-offs; patent issues aside?

I have always loved my Epicenters. Not always needed, but on something like Van Halen's 1984, it is an absolute must if you can add it into your system's design.

I hope AudioControl once again returns to its glory days. I would love to see a 6 channel DQT product or AudioControl head unit.


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## cleansoundz

DiMora said:


> Or, for an another viewpoint - how about those of us that want bass restoration buy genuine AudioControl Epicenters that are made in Washington state and support some American jobs instead of Chinese knock-offs; patent issues aside?
> 
> I have always loved my Epicenters. Not always needed, but on something like Van Halen's 1984, it is an absolute must if you can add it into your system's design.
> 
> I hope AudioControl once again returns to its glory days. I would love to see a 6 channel DQT product or AudioControl head unit.


Agreed I just reinstalled my Epicenter after about 2 1/2 weeks of using my Arc Audio KS 1000.1BX with the built in epicenter. It worked good but not like my Epicenter.


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## envisionelec

DiMora said:


> Or, for an another viewpoint - how about those of us that want bass restoration buy genuine AudioControl Epicenters that are made in Washington state and support some American jobs instead of Chinese knock-offs; patent issues aside?
> 
> I have always loved my Epicenters. Not always needed, but on something like Van Halen's 1984, it is an absolute must if you can add it into your system's design.
> 
> I hope AudioControl once again returns to its glory days. I would love to see a 6 channel DQT product or AudioControl head unit.


I only bought it out of curiosity. I have given away several Audio Control pieces; that's about how much I think of their usefulness with the availability of today's technology 

I can't justify spending $200 for one album. If the songs don't have enough bass - well, that's the way it was recorded. Tastes vary.


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## DiMora

envisionelec said:


> I only bought it out of curiosity. I have given away several Audio Control pieces; that's about how much I think of their usefulness with the availability of today's technology
> 
> I can't justify spending $200 for one album. If the songs don't have enough bass - well, that's the way it was recorded. Tastes vary.


I added my old-school Epicenter to my modern system. (Alpine Imprint). I love it - it makes a huge difference.

Their stuff is quite useful in certain systems.


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## TrickyRicky

I still dont get it, what exactly does an epicenter do? Because for all I know its a bass booster (which can be accomplished by HU or crossover). Not only that, it makes music un-real not like it suppost to be.

Am with envision if the music was recorded with low bass then thats how it should be played.


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## DiMora

TrickyRicky said:


> I still dont get it, what exactly does an epicenter do? Because for all I know its a bass booster (which can be accomplished by HU or crossover). Not only that, it makes music un-real not like it suppost to be.
> 
> Am with envision if the music was recorded with low bass then thats how it should be played.


Remember that engineers EQ songs so they sound good on small studio monitors, and therefore the crappy car stereos and I-Pods with the crappy earbuds that 99% of Joe Q. Public use...after they further desecrate the signal with MP3 compression, satellite radio, or FM radio transmission.

The end result is an over-boosted compressed signal, with dynamic limiters employed during mastering, and the loudness cranked way up.

One of the other results is the bass often gets limited so it sounds good with the paper whizzer cones in your neighbors Honda CR-V.

So....the Epicenter looks at your lowest notes in the music you are hearing, then it creates a fundamental that is one octave lower than what your music actually has in it.

Is it fake? Yep. Does it sound awesome? Yep. Will I have an Epicenter in every system I build? Yep.

The beauty of it is at it is like having salt, pepper, seasoned salt, Tabasco, A1, ketchup, or Frank's red hot right there when dining...you don't always need it, but when you do, it is essential.

I promise you, if you get one, you will use it more often than not.

You can always turn it off...but you won't.

Those who don't have it have no clue what they are missing.


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## TrickyRicky

DiMora said:


> Remember that engineers EQ songs so they sound good on small studio monitors, and therefore the crappy car stereos and I-Pods with the crappy earbuds that 99% of Joe Q. Public use...after they further desecrate the signal with MP3 compression, satellite radio, or FM radio transmission.
> 
> The end result is an over-boosted compressed signal, with dynamic limiters employed during mastering, and the loudness cranked way up.
> 
> One of the other results is the bass often gets limited so it sounds good with the paper whizzer cones in your neighbors Honda CR-V.
> 
> So....the Epicenter looks at your lowest notes in the music you are hearing, then it creates a fundamental that is one octave lower than what your music actually has in it.
> 
> Is it fake? Yep. Does it sound awesome? Yep. Will I have an Epicenter in every system I build? Yep.
> 
> The beauty of it is at it is like having salt, pepper, seasoned salt, Tabasco, A1, ketchup, or Frank's red hot right there when dining...you don't always need it, but when you do, it is essential.
> 
> I promise you, if you get one, you will use it more often than not.
> 
> You can always turn it off...but you won't.
> 
> Those who don't have it have no clue what they are missing.


I hear ya', but I've never used one and even took out a couple for a two friends that where complaining about how bad their systems sounded. One of them I didnt even told them I was taking out the Epicenter, then when I did I let him hear it and told me it was way better than before.

I dont see myself ever using it, didn't when I was a teen so why would I now.


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## DiMora

TrickyRicky said:


> I hear ya', but I've never used one and even took out a couple for a two friends that where complaining about how bad their systems sounded. One of them I didnt even told them I was taking out the Epicenter, then when I did I let him hear it and told me it was way better than before.
> 
> I dont see myself ever using it, didn't when I was a teen so why would I now.


Because it rules.

There is no need to uninstall it...it has a knob...and you can turn it down or completely off if desired.

If he had sound quality issues, it was not due to the Epicenter.

By all means, if the its result is not desirable, then there is no need for it, but I have yet to observe someone listen to it and say they did not like it with one exception: With male vocal only singing, or with talk-radio, if you turn it up, it does indeed have a "fake" effect where one can tell the voice is processed (and deeper than in real life)...but those are the cases where you turn it either down or completely off.

I commented to my buddy yesterday that I am glad I can still use this piece with my Alpine Imprint - it is one of my favorite units in the system. One quick play of Van Halen's 1984 (which has virtually no deep bass - it is a terrible recording) and the Epicenter proves its merit.


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## cleansoundz

Both of my vehicles hav the epicenter installed. It's a nice piece if used properly. I listen to lots of oldies so it comes in real handy.


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## GibTG

Sorry to bring a thread back from the dead, but does anyone have one of these RCA units sitting in a closet somewhere? As cheap as they are, I'd like to have one of these to play with, but they are no longer available new online.


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## PPI_GUY

GibTG said:


> Sorry to bring a thread back from the dead, but does anyone have one of these RCA units sitting in a closet somewhere? As cheap as they are, I'd like to have one of these to play with, but they are no longer available new online.


You've got a PM.


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