Ampeg BA-108 Coffeeshop Micro Rig

[Woodstockz]

Wondering if it would be worth buying a second 108 to modify with the Fane speaker, then do an A-B test...

I'd already ordered an alpha 8a when the fane posting came up. The Fane looks very interesting and on paper looks like a big winner over the alpha 8a. I just wanna know if I should ship back the alpha 8a when it finally comes in favor of the fane or not.

Btw woodstockz, thanks for looking into doing some looking into these speakers.

I am in the same boat on ordering speakers.

After Ukiah mentioned the Faital, I looked around at some other speakers. I ordered a B&C 8NDL51. It looked really good on paper. Very close to the Faital, with just a little less xmax.
Then the Fane came up. I will keep the B&C and will test both.

Since I already cut out the box for a 10 incher, I have to make a donut adapter to hold the 8.

 

[Woodstockz]

Since we're talking about 8" replacement/upgrade speakers...
I put an alpha 8a in a Fender Rumple 15 that I had kicking around, after lining the cab with damping material. I'm noticing that when I get to "5", it starts to fart out on me on anything below an A. I'm thinking a couple of things:
1. This speaker wants a bigger cab,
2. I need to glue the seams (maybe what I hear is a subtle rattle),
3. My expectations are too high for this little guy.
Any other thoughts?

Try modeling your box in WINISD with the new speaker. Maybe your port is too small for the new speaker?

 

[xk49w]

Here's another one - same price as the Alpha. I tuned it to 55 Hz to get an extended shelf type of response.

 

[bnolsen]

Couldn't you similarly return the cab down a touch with the alpha 8a driver and get a similar result to your tuning with the celestion? Btw, what's the tuning of the default port?

 

[xk49w]

Couldn't you similarly return the cab down a touch with the alpha 8a driver and get a similar result to your tuning with the celestion? Btw, what's the tuning of the default port?

The Alpha really needs more volume but it could be tuned down some, though the peak around 110 stays. There always seems to be some kind of compromise when trying to fit a driver into a given volume, and this volume is pretty small. Still, it has been a fun project that worked out well for me. I measured the stock tuning at 70 Hz. Here is stock driver TSPs.

 

[VeskuFIN]

Seems to me that Alpha starts working better around 1ft3 of enclosure volume. In the picture below yellow is Fane, green is Alpha in BA108's enclosure, and orange is Alpha in 1ft3 enclosure.

 

[VeskuFIN]

By the way, WinISD seems to give somewhat wrong values for Alpha by default. It's better to update them according Eminence's webpage.

 

[gary m]

Dancing with the thought of ordering the Fane and doing the old fashioned ear test. Should be better than the Alpha, given higher sensitivity and greater Xmax values. We shall see.

Also starting to get visions of a 108 mini stack by connecting two modded units in series and stacking them vertically. The head spins.

 

[bnolsen]

Also starting to get visions of a 108 mini stack by connecting two modded units in series and stacking them vertically. The head spins.

lots of knobs but why not? Gotta do something with those line out jacks.

 

[-Asdfgh-]

The Ampeg BA108 puts out 35 watts.
The Precision Port is advertised to give a 3 dB gain.
The Eminence speaker was measured to give a 2.5 dB gain over the BA110 speaker.
Pretty good SPL for this project.

Parts Express lists the Eminence S2010 at $139.99. I got the Eminence S2010 speaker for $112.49 at Amazon, but it has gone up since then. Still, the portability is worth it for me.

I have an S2010 lying around as I was considering building a cab for it (I have a 30lb 1x15 cab, but something smaller might be handy at times although I have an old 1x12 Trace combo for bar jams). I gave up with the woodworking aspect as I was on a highway to nothing trying to make it lighter than the 1x15 but maybe an old tatty and not too heavy cab the size of the BA108 in a pawn shop might be an option after all.

 

[-Asdfgh-]

Dancing with the thought of ordering the Fane

Fanes were the thing back in the day and it was a Fane in my first amp. It wasn't new when I got it and must be 30 years old now. I gave it away and it is apparently still going.

 

[bnolsen]

Maybe not the right place to post...I have an alpha 8a driver sitting not yet installed (just been playing the 108v1 stock). I was wondering what's the best way to quantitatively measure the ba108's response before and after the speaker swap?

 

[gary m]

Probably just your ears. If you wanted to measure more accurately, you might use a decibel meter and a spectrum analyzer to determine volume level and frequency response. I don't have those tools, so ears it is.

 

[bnolsen]

Ugh. Well I do have 3 very good usb mics. All with different setups (samson go mic, mxl ac404, zoon h2n). I guess I could try to set up some sort of test field, just would need to find some suitable test tones to run through it or something like that. Worth opening a new thread?

 

[Woodstockz]

Probably just your ears. If you wanted to measure more accurately, you might use a decibel meter and a spectrum analyzer to determine volume level and frequency response. I don't have those tools, so ears it is.

You can test Subjectively and/or objectively.

Subjectively, you can use your ears as gary_m suggested.
First, slowly crank up the box with the stock speaker until it starts to fart out, and make a note of volume position. (about half volume)
Next, do the same thing with the new speaker, and note volume position. (almost full volume). Did you break any dishes?
Useful, but not very scientific.

Objectively, you can do some 1 Watt at 1 meter testing.
Put the speaker in the middle of the back yard on it's back. Place the mic or decibel meter in a mic stand to hold it 1 meter above the speaker.
Put a sine wave on the input, and adjust volume for 2.83 Volts measured at the speaker. Why 2.83 Volts? Power = V**2/R = 1 Watt.
Make a spreadsheet of frequencies to test over the audio band. Compare stock and upgrade.
The responses will be spikey, like a porcupine, due to resonances. Not smooth. Where one speaker peaks, another one may dip.
Put all of your readings into a spreadsheet and do some averaging. Compare stock and upgrade.

 

[Woodstockz]

You can test Subjectively and/or objectively.

Subjectively, you can use your ears as gary_m suggested.
First, slowly crank up the box with the stock speaker until it starts to fart out, and make a note of volume position. (about half volume)
Next, do the same thing with the new speaker, and note volume position. (almost full volume). Did you break any dishes?
Useful, but not very scientific.

Objectively, you can do some 1 Watt at 1 meter testing.
Put the speaker in the middle of the back yard on it's back. Place the mic or decibel meter in a mic stand to hold it 1 meter above the speaker.
Put a sine wave on the input, and adjust volume for 2.83 Volts measured at the speaker. Why 2.83 Volts? Power = V**2/R = 1 Watt.
Make a spreadsheet of frequencies to test over the audio band. Compare stock and upgrade.
The responses will be spikey, like a porcupine, due to resonances. Not smooth. Where one speaker peaks, another one may dip.
Put all of your readings into a spreadsheet and do some averaging. Compare stock and upgrade.

This is what I did with the BA-110.

Objectively, the stock speaker farted out at about half volume.
The Eminence S2010 never farted out. However, I did begin to hear some amplifier distortion at around 90% volume position.

Subjectively, in 1Watt/meter sine wave tests, the S2010 avaraged about 3 dB louder than stock.

I used a signal generator to input sine waves, and adjusted the output to 2.83 Volts for each frequency.
I didn't get much below 80 Hz. Then I realized that they designed in an HPF.


...Then I crammed the S2010 into the BA-108.

 

[experimental bassist]

I couldn't resist...

This thread and all the other threads praising the BA108, PLUS my own great experience owning an old (vintage?) BA210, PLUS how much I love my BA112 for small gigs, PLUS my own auditioning the entire BA line few months ago when I bought my BA112 and being so impressed with the little BA108, PLUS the fact that the V1's are being phased out in favor of the V2's, PLUS the fact that my BA112 is just a bit big for a full time living room amp, all this meant that I was practically FORCED to pull the trigger and order my own BA108.



Should arrive sometime next week. Looking forward to adding to my BA collection.

 

[bnolsen]

I keep my ba108 on a coffee table that currently sits up against a wall (to make space for my rotten kids to trash the room with toys). I used to keep the genz benz combo next to the coffee table but I was always afraid I'd forget to unplug the amp and then some munchkin might crank it and flip it on. I'm not quite as concerned with the damage the ba108 could do.

Hopefully you got yours at good discount like I did mine. I think the tone is really impressive.

 

[experimental bassist]

I keep my ba108 on a coffee table that currently sits up against a wall (to make space for my rotten kids to trash the room with toys). I used to keep the genz benz combo next to the coffee table but I was always afraid I'd forget to unplug the amp and then some munchkin might crank it and flip it on. I'm not quite as concerned with the damage the ba108 could do.

Hopefully you got yours at good discount like I did mine. I think the tone is really impressive.

Got my little BA108 today, the tone is really impressive indeed, and yep, got a silly great price through MF.

NAD thread here.

 

[Dondabass]

I have a question for you guys...my Alpha 8a will be here soon. What is the best way to glue the seams of the BA-108 cab?