House Jam Micro Cab

[Pea Turgh]

2 hours ago, Mediocre Polymath said:

So I've been tinkering away on a mini speaker project very similar to this one, something small enough that my dad could easily take it to open mics and house jam things. It was going to be a christmas present, hence me working on it today.

 

Like CBD, my attempts to model a flat response curve with the Fane speaker were a bust – I'm guessing they've changed the specs since the original House Jam cabs were made. No matter how I played around with cabinet volume and port tuning, it always had a pronounced 4–5-dB spike around the tuning port frequency and then a drop in efficiency between 100–160 hz. WinISD twiddling suggested I'd have better results with a Faital 6FE100 and a slightly larger cab (about 13.5 litres) tuned to about 65 hz, so I went with that.

 

I built the cab and finally wired it up this morning and while it sounded good for about two minutes, it quickly started distorting, then crackling, then cut out entirely. I was only driving it with a MarkBass 250-watt amp, running at 8 ohms and about 1/4 volume, but yeah, it dead.

 

Any idea where I blundered here? Was my port tuning too low? 

Oh no!  Must have been a duff driver?

[Mediocre Polymath]

Just now, Pea Turgh said:

Oh no!  Must have been a duff driver?

I'm inclined to assume it was something I did, I've never had problems with Faital drivers in the past. Might try again with the 6FE200 and a port tuned to about 80hz.

[RhythmJunky]

12 minutes ago, Mediocre Polymath said:

I'm inclined to assume it was something I did, I've never had problems with Faital drivers in the past. Might try again with the 6FE200 and a port tuned to about 80hz.

 

Is it working again or has something died ?

 

I'm no expert on cab building, but do have some electrical experience and don't really see how a cab could cause that. I'd have thought a duff driver, or maybe a wiring issue somewhere. Have you tested the speaker impedance with a DVM since this experience?  

 

Anyway, I'm sure one of the grown ups with real experience will be along to help soon. 

[bremen]

The excursion would have been huge below 65Hz with more than a few watts, easy to kill a driver that way. (I've learned from my mistakes and can repeat them perfectly)

Edited yesterday at 15:49 by bremen
corrected as it's not 80Hz tuning

[Mediocre Polymath]

1 hour ago, bremen said:

The excursion would have been huge below 65Hz with more than a few watts, easy to kill a driver that way. (I've learned from my mistakes and can repeat them perfectly)

Yeah, I think I probably over-reached with what I could reasonably get out of a 6-inch speaker. Interesting learning experience though, and it wasn't particularly expensive to learn. I'm mostly just pleased with how the cab itself has turned out. It was more a sewing exercise than a can building one. The speaker/wiring is the most straightforward part of the process.

 

 

 

Look! built in cable pockets!

Edited 23 hours ago by Mediocre Polymath

[Chienmortbb]

Faital Pro’s FE range of drivers is not really good enough for bass drivers IMHO.

 

@Phil Starris right about Piezo tweeters however Motorola, the inventors have convinced everyone that you only need a resistor in series to crossover. Not true, the  resistor protects the Piezo but does little to the response. To successfully use a Piezo you do have to use a traditional crossover which does take many of their perceived benefits away. In addition the small round one, as shown in the pictures above are only good above 4KHz, way past where most LF drivers start beaming. This makes it very difficult to get a decent dispersion and the dip, off axis, is right in the area that the ears are most sensitive to. 
 

more piezo information here https://www.grc.com/acoustics/CTS_Piezo_Tweeter_AppNote.pdf

 

[bremen]

I've never heard a system involving piezos that hasn't had that dreaded tizz and boom quality, redolent of village hall discos, karaoke and cheap lager.

 

Apparently it can be done though, I think BFM knows the secret...