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Peavey MegaBass Club

#21
BbbyBld,

Megabass question....

Can you please describe the warning signals on these amps... I'm aware there's a random condition that causes them to DC out.

How would we know before frying our speakers?
Click to expand...

I'm not aware of a particular problem with these amps, but, some PWM-type class D amps are capable of "overmodulating", which means that a MOSFET is no longer switching on and off, so it sticks on, which sends DC directly to the speaker. That can happen if you run a class D amp without the limiter and you drive it too hard.

Sometimes, DC offset is an issue with class D amps. That can be checked with a voltmeter if you are concerned, but again, I'm not aware of this amp having an issue with that.

Other than that, a shorted MOSFET can cause a class D amp to output DC until a protection circuit kicks in, or the fuse blows.
 
#23
Bobby,

Is the reason why DC passing thru this amp being a non issue is due to the fact that the DDT compressor/limiter is always on?

In order to check this with a VOM on any amp would I would have to wait until the output is actually shorted, or do they sell a device that allows you to monitor DC output before the xsistor gets stuck in the on position?

I'm not worried about the Mega but I could use such a device on my other amps.

Thanks for your contribution to this thread
 
#24
Is the reason why DC passing thru this amp being a non issue is due to the fact that the DDT compressor/limiter is always on?

In order to check this with a VOM on any amp would I would have to wait until the output is actually shorted, or do they sell a device that allows you to monitor DC output before the xsistor gets stuck in the on position?

I'm not worried about the Mega but I could use such a device on my other amps.
Click to expand...

That's why the DDT is always on. If you had reason to suspect that the DDT stopped working and the amp starts clipping, get it fixed. Also, DDT has only so much gain reduction capability, so if you really try, it's possible to clip even with DDT, which is why Peavey has always told customers DDT light flashing with signal is cool, DDT light always on is bad. Stick to that and you're good.

Actually, the way the DDT was implemented on this amp was patented. If you are interested in learning more about the technology in this amp, use the patent numbers on the back of the chassis in google. Later model Peavey class D amps had another patented failsafe so that DDT could be turned off or fail safely.

If you wanted, you can always run a meter set to read DC across the speaker output. You should read virtually nothing on most amps.
 
#26
Thanks Bobby. I wasn't aware I could run a patent number to read up on the technology of said patented device. Learn something new everyday!:)

I like the "set it and forget it" simplicity of this amp. Not being a fan of compressors (probably because I haven't spent a lot of time tweaking them) this built in one doesn't squelch the sound and gives me lots of dynamic control, something I've found lacking on other external compressors I've owned. I used to own two basses where the E and A string would come booming out and the G would disappear when played over a band. The first night I gigged with this amp it equalized the volume on all 4 strings...I still can't believe how great these amps were (and are)
Thank you again for all your knowledge
 
#27
cflbass said:
I still can't believe how great these amps were (and are)
Click to expand...

Just had to sound off to some people who care about this... I did another gig with my MegaBass last night and tried to do a set with another amp as a comparison. I won't mention the contrast amp, because it's a currently-produced unit made by an awesome company. But the Mega blew the doors off this other amp. Sounded better by a mile. Not sure which was louder, as both have plenty of juice, and I couldn't crank them way high. This was a medium-sized bar gig with no bass through the PA. The Mega bi-amped into two 8 ohm cabs blew the doors off this place. Once again, I had to use the input pad to calm the thing down. It's just a perfect gigging amp. Period.

Hey, there's another one on eBay. Looks prett chewed up, but still working... Maybe we can recruit another club member!

--Steve
 
#28
I'm there with ya, Steve. Still waiting for GC to ship the one you turned me on to. Hopefully they didn't get the order mixed and send it to somebody else:hmm:

I'm in the process of A/Bin'g everything I can find on the used market in the >400 range. If I find something better I'll post it.
So far, nothing comes close, and needless to say, I've been returning a lot of amps!:)
 
#29
#31
Stev187 said:
Not sure that it would be better, but I've been looking for currently-produced amps with the same kind of flexibility as the Mega and come across this:

[Invalid or Expired Link Removed]

Anybody here try the Carvin BX1500? There some info here in the TB archives, but anybody out there who can compare it to the MegaBass?

http://www.talkbass.com/forum/f15/carvin-bx1500-first-impressions-811943/

--Steve
Click to expand...


I too am intrigued by this amp. The fEARful guys love them, and that or a Genz Neo is going to be my next cab.

Another amp I'm looking at is the GBE1200 or GB Shuttlemax 12.0.

Thanks Steve for the heads up on that MB from GC....it arrived last week and this thing is MINT...even the SKB case is in good shape.
 
#32
cflbass said:
I too am intrigued by this amp. The fEARful guys love them, and that or a Genz Neo is going to be my next cab.

Another amp I'm looking at is the GBE1200 or GB Shuttlemax 12.0.

Thanks Steve for the heads up on that MB from GC....it arrived last week and this thing is MINT...even the SKB case is in good shape.
Click to expand...

The fEARful guys love the Carvin? (or the Mega?) I've thought that building a fEARful might be an interesting project some day. I was wondering which design would work best with the MegaBass. Right now I am using the Mega with a 2x10/1x15 pair on gigs. Sounds great, but it would be cool to have a single cab solution for that.

A MegaBass popped up locally on Craigslist this week. Trying to resist the urge to get a backup. Glad that GC amp turned out great. Congrats.

--Steve
 
#33
P.S. Here's my 10-year old kid using the Mega on a recent gig. He's in a band with other 10-12 year olds and they open for their band teacher. Kid is working more than I am these days!!!

owen_rig.jpg
 
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#34
The Carvin is what a lot of the fEARful guys have. Based on their recommendation, plus the similar attributes of the adjustable x-over/dual power amp design I'm intrigued by this amp.

The GB shuttle is about the same price $/watt, and I saw a GBE1200 Lead Sled for 699 used on GC's site with five stars.
I have a feeling I'll be buying another amp to backup my MBs :)

The fEARful 15/6 sounds like it might be a good fit for your current situation. My cabs are all 4x10s but having used them for 20 years I want to try something new. The 15/6 and possibly 15sub will be what I'll build.

I believe Greenboy has stated the cabs all pretty much sound the same, its a matter of footprint/schleppage factor and power handling.

I'll let you know if I pickup a Carvin or build a fEARful and A/B it with my current rig.
 
#36
May I please have a number?

Here's mine, in pretty tatty shape:

This picture makes it look better than it is. Someone with really sweaty fingers turned it on and off and adjusted the controls a lot of times, because the finish is corroded right off.

After working perfectly for years, the biamp feature may be dodgy because when I plug it into my 1820, it sounds exactly the same plugged into full range and biamp.

Here's the story. I saw one, brand new, in Center Music in Framingham, MA in the '90's. It looked about as sleek and professional as an amplifier can look. It looked space age. The price was way beyond what I could afford. It was unattainable.

Years later I was demo-ing a cabinet at GC and they had a used MB. I'd never heard one but boy was I excited and had them hook it right up. It was about the fattest, cleanest, most gorgeous musical bass tone I had ever heard. To this day, I maintain the MB is not an amplifier, it is a musical instrument.

That it has loads of power, seemingly way beyond its rating, is just icing on the cake. The power just assures that there is no bass tone this thing will not beautifully reproduce.

Not long after the demo, I went to one of the old Daddy's Junky Music warehouse sales in NH. It was like harmonic convergence, or synchronicity or something because there it was. I could not believe it. The coincidence was just too much. I was not at all in the market for an amp but there it was! I walked all around the place but kept coming back to it. Finally what I now consider my better judgment took over and I bought it.

Now when I think about it, I wonder why I ever hesitated. Not just because it sounds so great, because of the price.

$100.00. Not kidding.

That had to be ten years ago. And it has never failed. Ever.

As time has gone on my tastes have changed a little, and I'm now using an old CS-800 with a Peavey Bassist preamp.

I found a guy in Manchester, NH who cleaned up the CS-800 for me, so if I ever want to get the MB back into fighting shape I know who to go to. I'm certainly never going to sell it.
 

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#37
bleepo said:
I had no idea people still used these! I've got one in a closet I haven't used in ages. Maybe I should dig it out. Its certainly lighter than my GBE1200...
Click to expand...

You want a number, or no, bleepo? Let me know. Current number list:

1 - Stev187
2 - Ayce
3 - jpknox
4 - MNAirHead
5 - cflbass
6 - uhdinator
7 - Five String

I found another one locally for cheap--will probably grab it.

--Steve
 
#38
Five String said:
After working perfectly for years, the biamp feature may be dodgy because when I plug it into my 1820, it sounds exactly the same plugged into full range and biamp.
Click to expand...

That might be your 1820, Five String. Have you tried the MB biamped into other cabs? I have a 1810 (nearly identical to the 1820) that fried an amp because the crossover was shot. Be careful with that thing. My solution was to remove the xover and just drive the 2x10 and 1x18 separately with the MB (one of the only heads I know that could do this). I leave that cab at the drummer's house.

--Steve
 
#39
Stev187 said:
That might be your 1820, Five String. Have you tried the MB biamped into other cabs? I have a 1810 (nearly identical to the 1820) that fried an amp because the crossover was shot. Be careful with that thing. My solution was to remove the xover and just drive the 2x10 and 1x18 separately with the MB (one of the only heads I know that could do this). I leave that cab at the drummer's house.

--Steve
Click to expand...

Ah, it was the crossover? Glad to hear you found the cause to your issue, Steve.
 
#40
Hi Steve - Good point. However, I run one CS-800 channel through the 2X10 and one through the 18 with no problem and clearly bi-amped.

But I have thought about doing exactly what you say, removing the crossover. My MB and my Bassist both have crossover adjustment knobs so I don't really need the crossover in the cab.

I think I probably need to remove the crossover from my 1516 because before the MB bi-amp got dodgy, I tried bi-amping that and got a lot of crackle. If I remove the crossover I can still run these cabs full range, can't I?

BTW, can't say enough good about the sound from the 1516 or 1820. Weight, well, that's another matter.
 

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