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Ampeg BA115 tweeter question

M

MarkMcCombs

Nov 26, 2000
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Lee's Summit, MO
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#1
Okay, just got one of these used. Of course, now I realize that these babies really have a LOT of tweeter hiss, crossover noise, whatever is the cause, I dunno.

Last night I unhooked the tweeter, easy enough. The amp sounded fine, didn't really notice the difference except for the absence of hiss.

Tonight, however, and after reading somewhere on some other board about doing this, I thought about by-passing the crossover and sending the whole signal to the 15", knowing it'll produce about 3-4khz, which should be fine. So I open it up and guess what, -- there is no crossover. 2 wires come from the amp and go straight to the 15s posts, and 2 wires also come off those posts and go to the tweet. No, there is no evidence that there is a crossover in or near the 15's speaker posts. Is a full range signal thus going to the tweeter, and I would guess also the 15".

Any thoughts?

Thanks,

Mark
 
#3
From http://www.colomar.com/Shavano/pa_speaker_project.html

"Piezoelectric drivers, from the viewpoint of your amplifier, look like a big capacitor, just like the ones used in passive crossovers with conventional woofer-tweeter combinations. So in a way, the crossover is built into the design of a piezo driver, because its impedance starts out ridiculously high at low frequencies (500 ohms or more) and thus rejects low-frequency sounds. This resistance to current drops as the frequency increases, until by the time sparking high frequencies come down the speaker wire, the piezo's impedance has dropped to double digits and those high frequencies come out of the driver at high sound-pressure levels because most piezos are very efficient. "
 
#4
Hi people, I have just been reading the thread because I bought one of the amps yesterday and mine also hisses; It's beginning to really annoy be already.

Can anyone recommend a replacement tweeter and where I can pick one up from in the UK? If not has anyone heard of acoustic dampening that will minimize the tweeter hiss? I've been told that cover the tweeter with a piece of carpet works. Up to now disconnecting the tweeter sounds best or maybe even returning the whole thing.

I thought this amp was made in the USA until I got home and read the back panel, it turns out they are made in China. That will explain the hiss and the cheaper parts.

I previously owned an Ampeg Portabass rig and that always, always broke down so I ended up selling it after having it repaired.

I only purchased this BA-115 because it was cheap and loud but the name on the front was putting me off slighlty because of my previous negative experience with the brand.

Ampeg, I'd recommed you sort out your quality control, listen to your customers and also state that the BA-115 is made in China not the USA.
 
#5
MarkMcCombs said:
Okay, just got one of these used. Of course, now I realize that these babies really have a LOT of tweeter hiss, crossover noise, whatever is the cause, I dunno.

Last night I unhooked the tweeter, easy enough. The amp sounded fine, didn't really notice the difference except for the absence of hiss.

Tonight, however, and after reading somewhere on some other board about doing this, I thought about by-passing the crossover and sending the whole signal to the 15", knowing it'll produce about 3-4khz, which should be fine. So I open it up and guess what, -- there is no crossover. 2 wires come from the amp and go straight to the 15s posts, and 2 wires also come off those posts and go to the tweet. No, there is no evidence that there is a crossover in or near the 15's speaker posts. Is a full range signal thus going to the tweeter, and I would guess also the 15".

Any thoughts?

Thanks,

Mark
Click to expand...


There are two ways this is usually handled. A true crossover will have a cap and a large inductor. This setup limits the high freqs from going to the 15 and low freqs from going to the tweeter. The high frequency going to the 15 will not hurt anything. The reason you limit high freqs to the 15 is to keep a balanced level. However, Low freqs will destroy a tweeter, though and that's why the cap is in place. Many speaker boxes just use a cap to filter the low to the tweeter. If there is neither a cap or inductor, ther is no crossover at all and your tweeter should pop pretty quick. :D
 
#7
This doesn't have to do with the tweetwe question but I didn't want to start another BA115 thread. So far I've only used my BA115 playing along with acoustic guitars. I haven't had to tutn it up no more than 3 or so. When using the BA115 playing along with electrics, what size(watt)guitar amp will it keep up with? Anyone on here use the BA115 for small gigs and if so, how big are the electrics guitars' amps? I'm talking for small gigs or jam sessions.
 
#8
MarkMcCombs said:
So I open it up and guess what, -- there is no crossover. 2 wires come from the amp and go straight to the 15s posts, and 2 wires also come off those posts and go to the tweet. No, there is no evidence that there is a crossover in or near the 15's speaker posts. Is a full range signal thus going to the tweeter, and I would guess also the 15".

Any thoughts?

Thanks,

Mark
Click to expand...
Hi Mark,

as the piezo tweeter has an own physical frequency point (resonance where the swinging of the piezo cristal sets in) where it starts working, it does not need a crossover at all.
This is a cheap and "dirty" construction, as the noise of the slave amp always produces some treble background frequencies which you can hear as obstucting "hiss".

So I hope I could explain both issues.
 
#12
A decent noise gate would increase the price of the combo drastically, and a low budget noise gate will affect the sound and dynamic of the combo badly. I suggest you either install a switch for the tweeter to turn it off or you adjust your trebles to a "low hiss" level if it still sounds well in your ears. On my BA115 I definitely realize the hiss when practicing alone, but it does not obstruct my sound expectation once I play with the band.
 
#17
With regards to the question on how can the BA-115 keep up with band volumes - I've never had a problem playing weddings, various club dates (using the DI out into the PA system or the amp to fill the room), theater gigs, etc.

My tweeter is intermittent - sometimes on, sometimes off. I'll try disconnecting the wires next time I am home. I definitely like the sound better without the tweeter.

imp
 
#18
mine was "hissing" or rattling. so i took off the handle sat down next to it and hit some notes. the damn tweeter was physically vibrating cuz of the magnet on the back. i stuck my arm in the hole and grabbed onto the tweeter and it stopped. so i took out the tweeter, unscrewed the magnet from it, put the plactic horn/tweeter back in place and shoved a black sock in the tiny tweeter hole. while i was at it, i put medium density foam around the perimeter of any metal that touched the cab. RAttle Free and sounds much better.
 
#19
Hey I just bought an ampeg BA-115, I have a muisc man stingray, its an active bass, When I play my E string open, I hear a little buzz, its that what you are talking about? It doesnt happend with the rest of the strings
 

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