funkle

I've tried to put as much info here as I can that Stevie and I exchanged....however I may need to go back over the PMs exchanged and see if there is more to add.

@LukeFRC I’m easy. I’m delighted for everyone to put theirs here. Equally, if it feels like it could be clunky, builders can start their own.

I’m really looking forward to hearing thoughts from other people, and seeing their builds. @Ghost_Bass I’m not sure if I’ll get to the trials of steel wool on the finish. I’m happy with how it looks and I just want to play it, lol.

A quick update after a lot more testing and a band rehearsal. I have measured the distance between the central woofer dome and the rear of the grille and I now have 37-38mm of space. That should be plenty for the woofer excursion. If it hits the grill, the driver is going to die...or is already dead... I sat down with my test setup and a comparison cab. The One10 is about half the size of the BC 112, lol. It’s actually not a bad cab to compare to. Long throw driver, well braced, rated for 250W though apparently will take up to 500W with clean sounds. So it’s a potent little driver, albeit a 10”. I maxed out the volume available from the One10 with the amp set optimally flat and the Gain at 3 o’clock and the Master at 12 o’clock. At that point I could distort the woofer with note accents. The One10 gives a very satisfying low end, easily comparable to the BC 112, but only up to a certain volume. I’ll call it jazz gig volume. It’s very good, but there are limits. it also takes a huge amount of bass boost before it farts out. Veiled top end, but enough, just. The cab clearly adds more colouration to the sound as it gets louder. It’s a nice colour and it really suits bass. It’s a great cab. Swapped over to the BC 112, leaving the amp set optimally flat. Gain at 3 o’clock and Master at 12 o’clock, as before. The upper mids and treble sparkle and the clarity is great. As expected, really. Cranked in max bass boost on the amp and the cab tolerated it at this level. Impressive for such abuse. Put bass back to flat on the amp and turned up. Could get the woofer to fart out with accents with Gain at 3 o’clock and the Master at 3 o’clock. It was stupendously loud; the wall and window shaking volume I described previously that will drown out any drummer and will definitely keep up with a full band. It remains clear at volume. Slapping at that point caused a click noise which I suspect might have been the voice coil hitting the back plate, or just a very unpleasant transient. It didn’t sound natural so I stopped doing that. (If it was the woofer travelling beyond Xdamage it would have been wrecked. It obviously wasn’t...lol...). Adding any bass boost at this point also caused woofer distortion. I am confident that this is the mechanical limits of how far the cabinet can go. I won’t go near this again; the amp can give a lot more but it will kill the cab. I started adding an HPF but had to stop to pick up the kids. Took the cab out to a very moderate volume keys/sax jazz rehearsal. Carrying it around was easy. Had to turn down the bass frequencies at the amp; otherwise I just plugged and played. Great sounds all night. The band loved it and the keys player may want to build his own after we tried the keys through it and it sounded amazing. I may have retired my One10 from the moderate volume jazz stuff. I have concluded two things. 1. The setting of volume knobs on the amp is not a good indicator of the power getting delivered. Basically this amp is very powerful and can distort woofers at settings far less than maximum. Not a surprise. 2. The BC 112 is a very capable cab. The BC cab reminds me a bit of the Faital-loaded Berg CN112. The same smoothness of the mids, mainly. However that cab was a little bass-shy; the BC 112 has more lows (more like the BF BB2). And the high end is smoother sounding than the CN112 as well, and extends higher also. I’m probably only going to bother with an HPF for loud gigs or rehearsals. In my ordinary use it doesn’t look like it will be necessary.

I’ll try it when I can. That will put the matter to rest. But first much more high volume testing, when I’m at home again.

Hmm. Now I’m confused what to try. Lol I threw away my original tester blocks after I finished the paint job. But will experiment when I can. Unfortunately my relative is now in a hospice and my time is fully occupied for a while.

That has always been the goal. I’m pleased. I have wondered about other tweaks as I have built. One was whether there is enough wood to allow the handle to be routed out to be flush mounted? Getting the grille right is another critical key to the look. I like my one. But I’d suggest taking time on the aluminium one to get it perfect.

Did some quick pics of the cab in its current state before I left this morning. Just for fun.

Thanks @stevie When I started testing, I did set the controls to optimally flat to start off with, and proceeded from there with bass boost etc. The Bass Gear Magazine article is very helpful indeed, in many ways, and learning how to set the GK flat properly was one of them. I’m trying to recall if there was a modest bass boost or not when I was getting the driver to hit the grille with moderate volume when playing G or below. I can’t reliably recall, so will simply have to re-test, with and without a HPF. I added the extra 6mm batten in last night and re-fitted the grill today. I did a dry run before doing any glueing and determined that the grill would be a very close fit indeed after adding the foam. The photos above demonstrate that well; it is just about flush fit now. So I have 21mm of batten installed now with 1mm of foam. 22mm total. That should be plenty of space. I’m not sure when I can next stress test; I’m all tied up with looking after an unwell relative at the moment. I’ll do some controlled testing when I can and report back. I’ll also be more methodical when I test as well.

How do you set up the compressor? As a normal compressor e.g. 4:1 with fast attack/release, or as a brick wall limiter (to protect the speaker)? I really like the treble from this cabinet and how it is presented. Not harsh.

Heh. I’m certainly trying. I’m not sure if the GK MB800 has an HPF built in. There’s nothing in the manual and I can’t find mention of it on Talkbass. I experimented with the Zoom B3 HPF and cannot see much difference playing into the GK front end with the cone movement with or without it. That implies there is some kind of baked in HPF in the head? (Edit. The other possibility is that the Zoom HPF doesn’t do as much as it should.) Nonetheless, I have attempted abuse of the woofer in other ways. Mainly dialling in huge bass boost to see how it reacts. Slapping is an excellent test of speaker cabs. It has a huge transient, plenty of low frequency information...and just about every bassist will do it when stressed, lol

Fascinating graphs. Look at the frequency responses of those classic cabs. Anything but FRFR...

I have experimented with the HPF in the Zoom B3 Fishman Preamp sim. It works great as usual at tidying up the lows, although to be honest turning down the bass knob on my instrument or the amp seemed just as good. I have had much more profound effects on other cabs with the HPF than on this one. I didn’t experiment it with trying to take the ‘click’ of the woofer hitting the grille. It might work, but I suspect the woofer just needs to have a certain amount of movement. The ‘clicking’ happened at very moderate volumes when I accented notes or slapped; I suspect a compressor set as a brick wall limiter would have been a better tool than the HPF, perhaps. TLDR; I think it was the power of the amp rather than any subsonics causing the cone travel.

No problem. I want to know before a gig what I can expect. Not during it...running out of enough cab is an unpleasant experience. Or suddenly finding that low G and below gives a horrible click every time you hit it at moderate volume, because the grille is just a smidge too close. No kidding. The mugs shook on the shelves, the windows rattled, I could hear walls vibrate. I felt a strong breeze from the port on low notes. On open A at max power, I actually watched the cab walk itself backwards an inch or two. My wife came in from the front of the house en route to somewhere else and said she could hear it out front (quietly). That is through a few stone walls and was about 40 ft away. This is clearly a capable cab. Eventually, when more cabs are built, you know someone, somewhere, will do this without knowing what they are doing...better to know how it behaves with borderline or outright improper use. As a side note. The preamp on the Celinders is legendary for putting out mega treble. I messed with it this morning and flicked the switches that give boosts in both lower and upper treble, just to see what it was like through this cab. Then cranked the volume up. Indescribably piercing. I’ve never had so much treble, ever, at that volume. It was a very clear, even treble, but just too much. I turned those switches off smartly. As it is, even without the boosts, both Celinder Updates I have (Jazz 4 and PJ4) need the treble rolled off a bit to be manageable through this cab. Running cab sims from the Zoom B3 into the cab, I am struck by how many of them clearly roll off the upper end, quite significantly.

Found what I need at B&Q. It will add another 6mm depth to the battens in one easy move. It’s 6mm deep and 11mm wide (in fact it’s probably 10.5mm, they just round up for some reason). Same width as what I already have. https://www.diy.com/departments/smooth-stripwood-t-6mm-w-11mm-l-2400mm-pack-of-1/1793539_BQ.prd Just a teeny bit more building and painting work now.

Agreed. I’m listening carefully for signs of distress. The most I’ve been able to cause by stressing the driver so far is woofer distortion. Thankfully no other worrying sounds... I’m interested in knowing the cab’s limits before it hits a gig. I definitely do stress cabs. But as carefully as I can. When I can, it will come to a rehearsal space with me, as basically I’ve found a smallish room with loud musicians is often more intense volume wise than many gigs. Lol... The only driver that has taken every form of abuse I can hit it with is the 3012LF. That thing caused my (500W into 8 ohm) power supply to cry for help. I never heard the driver ever distort with that power level. Slapping a B string with max bass boost on amp and bass; it never sweated. Insane. But of course it lost midrange sensitivity because of that LF performance, and to my eye needs crossed over to another driver around 1.5kHz (maybe 2kHz if you can live with the spike in response). I never asked, but at what frequency does the crossover shift things between the drivers?

Thanks @stevie I agree, I’ve been thinking about solutions and the best is to add more batten height. I’ll strip out the foam I’ve got and install some more batten. The current batten is probably going to be very hard to remove, so I might have to look for very narrow strips to glue on top of the existing batten. Don’t sweat sending me anything, I’m just going to measure everything again and then hit either B&Q or Wickes to buy something suitable.

Good morning all I was testing the cab out further again a bit yesterday evening and today. I’ve had to cancel some gigs due to a family member being unwell, which led to a little extra time alone at home. Everyone else was out of the house, so I cranked the GK’s gain and volume up. I noticed a metallic ‘clank’ noise when I got everything up to about the 12 o’clock on both, which is moderately loud but not excessive. I hadn’t noticed it previously in testing the cab (hint: my previous higher volume testing was done with the grille off...). It seemed to come at notes hit hard around ‘G’ on the E string or below; it was only present during volume spikes, not when I played softer. It seemed pretty odd to happen at what was well within the cab’s capabilities previously. This was obviously concerning, but I soon worked out the cause. I was afraid it was the voice coil hitting the back plate with a voltage spike with the low notes. Or the woofer cable hitting the back of the woofer. Neither was the case. It’s the grille. I screwed my grille in fairly firmly, and iI think the cone is hitting it when I slapped or accented lower notes. I took the grille off and worked my way up to max on both the gain and volume controls. Pretty intense testing....insane volume....no metallic ‘clank’ noise any more. Whew. (I could still make the woofer distort a little if I push it that hard/at that volume, or cranked in more bass. That seemed normal to me, every cab has its limit somewhere.) My conclusion. At very high volume transients it appears to be possible to get the woofer to touch the grille, currently. (The alternative explanation, that the grille simply vibrated a lot with those spikes, didn’t seem to be the case when I pressed on it or checked the fit again.) I will need to perhaps add another layer of foam to the battens and experiment. As context. The GK MB800 is a very powerful amplifier, and the Faital woofer is rated at 300W AES (max 600W). I double checked the bench test output from the GK from Bass Gear Magazine and I attach the info below for context. The GK delivers continuous power at near max handling of the driver, and burst power beyond it. (Dependent on THD %)