AVS › AVS Forum › Audio › DIY Speakers and Subs › Modifying Bash 500 amp
New Posts  All Forums:Forum Nav:

Modifying Bash 500 amp

post #1 of 10
1/22/10 at 2:58pm
Thread Starter 
Hi guys, need help.

I have an unmodified Bash 500 amp that I'd like to use temporarily for the IB project that I have going on. Financial advisor (Wife) is not in agreement with me spending money on a new amp at the moment.

The help that I need is modifying the Bash high pass. So far, I have found the formula to figure out what resistors I'd need but for the life of me, I cannot figure it out.

m=Q^2 * 4
R17=1/(2*pi*2.2e-7*fc*sqrt(m))
R18=R17*m

To me, that's not a language spoken by any human!!

Can someone please help??? I need to know which resistors to buy and how far down I should go as far as the high pass is concerned.

Another thing, once I'm able to buy the proper amp for the IB, this Bash 500 is going to be relocated into another sub with a 12" Titanic MKIII so eitherway I'd like to change the high pass on the amp.

BTW... I emailed and chatted with Parts Express tech support (some guy named Chris Frechette) and he must have been the absolute most CLUELESS tech I have ever been in contact with!! Completely worthless. Didn't even know that the site page for the Bash amp on their own website has a pic and spec sheet with resistor values for the mod. He also kept confusing the specs on the Bash 300 for the Bash 500.
Reply
Reply
post #2 of 10
1/22/10 at 4:53pm
I've modded 2 of them so far, what are your goals?

Need to know the high-pass frequency you want and the desired bass boost (if any).

Then, it is just a matter of removing and replacing two resistors. Not too hard, I managed it without too much drama.
Reply
Reply
post #3 of 10
1/22/10 at 7:19pm
Thread Starter 
Quote:
Originally Posted by lilmike View Post

I've modded 2 of them so far, what are your goals?

Need to know the high-pass frequency you want and the desired bass boost (if any).

Then, it is just a matter of removing and replacing two resistors. Not too hard, I managed it without too much drama.

Thanks for the help lilmike...

Actually, I don't know how low I'd like the HPF. Is aiming for 15hz too low? As for the boost... don't know either.

Also, the amp's final home will be with the 12" Titanic sub in a ported box tuned to 20hz but for the next couple of months, it's going to be mated to (qty: 2) FiCar IB3 18" woofers in an IB setup until I get the green light to buy the proper amp for them.

I can do the soldering but I feel like my brain is on "STOP" when it comes to what I want to do with the Bash amp.

Let's put it this way... I'll go with what the general concensus thinks is good.
Reply
Reply
post #4 of 10
1/23/10 at 5:21am
Thread Starter 
Looking back at some old threads, I came across someone that was modifying theirs to go for:

Fc = 12Hz
Q = .9

Resistors needed to reach above target according to thread:

R17 = 34k
R18 = 108k

Does this look correct? If it does, I'm going to try to get these resistors locally today.
Reply
Reply
post #5 of 10
1/23/10 at 2:38pm
That's what I came up with.

110K and 33K should be close enough.
Reply
Reply
post #6 of 10
1/23/10 at 4:45pm
Thread Starter 
Quote:
Originally Posted by lilmike View Post

That's what I came up with.

110K and 33K should be close enough.

Thanks again!!! Now, last question...

There are 1/2 watt and 1 watt versions. Which one do I pick up?
Reply
Reply
post #7 of 10
1/23/10 at 6:44pm
1/4 watt will be fine, anything larger will work, but will be harder to fit into the space available.
Reply
Reply
post #8 of 10
1/23/10 at 9:16pm
Thread Starter 
Quote:
Originally Posted by lilmike View Post

1/4 watt will be fine, anything larger will work, but will be harder to fit into the space available.

Can only find 1/2 watt. I guess it's fine since I can mount them on the rear of the board.

33k is easy to find
110k for some reason is not. Which would work instead 100k or 120k?
Reply
Reply
post #9 of 10
1/23/10 at 10:58pm
Quote:
Originally Posted by chucky08016 View Post

Can only find 1/2 watt. I guess it's fine since I can mount them on the rear of the board.

33k is easy to find
110k for some reason is not. Which would work instead 100k or 120k?

120 K takes the corner frequency down a touch lower. That's probably the better choice.
Reply
Reply
post #10 of 10
1/24/10 at 7:47am
Thread Starter 
Quote:
Originally Posted by lilmike View Post

120 K takes the corner frequency down a touch lower. That's probably the better choice.

Thanks!!! I'll document the mod as I go.
Reply
Reply
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: DIY Speakers and Subs
AVS › AVS Forum › Audio › DIY Speakers and Subs › Modifying Bash 500 amp