|
|
Post by Deleted on Jun 15, 2018 14:53:28 GMT
That first one was handy salteedog. Good one. Mind you, I wouldn't have to do any of that if I could get the front grille off. I'll have to take those 4 screws out again and see what is stopping it from popping off. |
|
|
|
Post by Deleted on Jun 18, 2018 17:36:51 GMT
I couldn't resist it any more; I just had to see if I could get that front grille off....I couldn't. Flipped the amp over and could see at least one bolt that might be holding it on so I decided to go for a full strip down and post the images here as I've not found anything like it anywhere else. If anyone wants anything else photographing or more info I'll gladly do it. It's just a matter of a big Phillips screwdriver and a little adjustable spanner. Here we go: Undo the four corner screws in the grille.  Undo the two screws each side of the handle:  Flip the amp over and take out the four screws in the corners of the chassis:  Now here you could just slip those speaker spade connectors off and completely slide out the chassis to get to the hidden bolt holding the grille on (there is an easy to see and reach one to the left of the speaker too).   But I also wanted to take the speaker out so took the whole assembly out.  Now the grille can come out by undoing those two black bolts above and to the left of the speaker opening.  It should be easy now to insert a doughnut baffle.  That little drop down T shaped piece in the grille's chipboard houses the screws that keep the Katana symbol and Boss logo annoyingly in place.  I decided to remove the Katana symbol which I hate and, just because I could, the Boss logo too. They are held on with bolts into the plasticky-tacky badges.  With the grille off it is easy to see how it could be covered with something more appealing; maybe some silverface cloth? Anything to lift this dull box! You'd just have to remove the staples holding the plastic edge clips in place and recover.  Any badges you fancy could be mounted where the old ones were to personalise the front a bit. I may look into whether I can make a band logo badge somehow. Any ideas how something could be moulded in metal or plastic? I do have a heat sublimation press at work so I could print something. Time for a think there. I believe I have a few blank mug mats. For the moment it's now an anonymous dull looking box instead of a badged dull looking box.  It needs a designer's eye now to improve the look of the thing. I'll be photoshopping like crazy next!  |
|
|
|
Post by Deleted on Jun 19, 2018 8:55:14 GMT
Baffle foam bought...99p delivered!  |
|
3,968 posts
|
Post by salteedog on Jun 19, 2018 9:04:59 GMT
Well that's a pretty complete dismantling. I'm glad to see it has none of those annoying clips that are used generously for car interior fittings and which I usually break after forcing.
As for the logo/anonymous black box etc....I actually don't mind it at all. My vaporizer on the other hand could do with some nice silverface grille cloth.
|
|
|
|
Post by Deleted on Jun 19, 2018 9:06:44 GMT
|
|
|
|
Post by Deleted on Jun 19, 2018 9:08:46 GMT
Well that's a pretty complete dismantling. I'm glad to see it has none of those annoying clips that are used generously for car interior fittings and which I usually break after forcing. As for the logo/anonymous black box etc....I actually don't mind it at all. My vaporizer on the other hand could do with some nice silverface grille cloth. I hate it. It might as well be a Blackstar it has so little appeal! I thought the Vaporizer had a pretty great look. Is it not so hot close up? <EDIT Oh god, yes, I see. Is that some kind of stretched nylon stockings material?>  I may change the plastic Blackstar-alike corner protectors too. This amp is in for the pimp of its life! Even that dopey, too short to do anything prop is in for a mod. |
|
3,968 posts
|
Post by salteedog on Jun 19, 2018 9:44:47 GMT
Yes the grill cloth on the Vape is particularly crap. 'Stretched stocking material' is as good a description as any!
|
|
|
|
Post by Deleted on Jun 21, 2018 13:09:47 GMT
My 99p delivered square of foam arrived so I went for the doughnut. The foam's 1" thick and easy to cut with scissors.  A 3" diameter hole in the middle and in she goes.  Cut it slightly overlarge so that it stays put. I did also pop some foam in the two slots at the top but considered they were more for heat loss than for acoustics so took 'em out again. Just played through the Kat and, lo and behold, that directionality is greatly reduced; not so much difference between standing up and sitting down which was my main area of worry. I even ventured to push my treble past 9 o'clock and didn't suffer the consequences. This has to be one of the best bang for buck mods I could ever do to an amp. Taking the postage out of the equation (I don't know whether Yodel will actually deliver for 99p!) it must have cost me about nothing or less than nothing. |
|
3,968 posts
|
Post by salteedog on Jun 21, 2018 14:23:01 GMT
Very interesting. The theory of how this works appears credible and your observations are backing it up. Have you noticed the amp sounds darker now when listened to 'on-axis'?
|
|
|
|
Post by Deleted on Jun 21, 2018 15:13:26 GMT
It's a good question saltee. As far as I can see the bass just pushes on through as though there was nothing there. I guess that's long waves for you. But I reckon there must be some top disappearing as I am able to use my treble knob far more than I used to be able to. I used to pretend it wasn't even there!
I wonder if there are any other shapes that people have tried to tweak the response? Star shapes? Slots either vertical, horizontal or concentric? Personally I'm happy to live with this for a while and try it at band practice. It will be nice to really open up the volume and see how it seems.
|
|
3,968 posts
|
Post by salteedog on Jun 21, 2018 16:08:55 GMT
Doughtnut shape makes most sense as it is entirely symmetric. Otherwise you are opening up the possibility of creating comb-filters where certain frequencies get dropped at different listening positions. I'd imagine the way to tweak this is to adjust the size of the doughnut hole, use a different foam material or use a different thickness of foam.
The theory as I read it is that with the doughnut the higher frequencies are now less beamed (so are spread across a bigger angled 'cone') and hence should sound more attenuated than it used to when listening 'on axis'. The off axis tone should be pretty much the same as it was before (i.e. comparably muddy). So now you will increase the mids/treble to compensate for that muddiness but hopefully the tone will be more consistent across the different listening positions.
|
|
|
|
Post by Deleted on Jun 21, 2018 17:11:58 GMT
What I'm finding seems to be exactly what Jay Mitchell who invented these things says, "A 12" speaker has huge variations in its response above ~1200 Hz within just 10 degrees of the speaker's axis. With the 3/4" foam doughnut in place, the on axis response and the response at 40 degrees off axis are almost identical. This is a huge improvement.
If you think about the subject of directivity, you'll easily recognize that there are two ways of saying the same thing: when you say a speaker becomes "beamy" at high frequencies, you're also saying that its on axis response is much brighter than its off axis response. For example, if you equalized the response to be flat on axis (a hypothetical exercise, as that's never what you actually want from a guitar speaker), you'd find that the response off axis falls off pretty rapidly at higher (> 1200 Hz) frequencies.
The reason for the preceding paragraph is to point out that making directivity more consistent over frequency requires that either the on axis or off axis response change. The foam doughnut causes a change in the on axis response, while leaving the off axis response alone. This means that, if you've tweaked your tone with the speaker aimed at your ears, it's now going to sound darker, and you'll need more treble, presence, and/or midrange, depending on the design of your amp's tonestack and other tone-altering circuits. If you're placing your amp on the floor facing the audience, the response you hear will change little or none, but the response the audience hears will now match what you've been hearing all along."[/b]
I had been tweaking my sound off-axis and then hating the beaminess directly in front so I switched to tweaking my sound on-axis but could never really get anything that wasn't too toppy and as nice as my previous off-axis sound...and it sounded wooly off-axis. Now I can get those tone knobs working as they should when on-axis, getting a nice tone and then don't lose that tone when I stand up or move around. Early signs are exceptionally good.
|
|
3,968 posts
|
Post by salteedog on Jun 21, 2018 17:38:33 GMT
Exactly. That's the article I read too. Very good to know this mod works.
|
|
|
|
Post by Deleted on Jun 28, 2018 22:03:33 GMT
Amp Shield probably does the same trick no?
|
|
|
|
Post by Deleted on Jun 29, 2018 7:47:27 GMT
Hi Che. No, an amp shield is just there to reduce the volume of an over loud amp. You may need to really roast the valves to get the sound you want out of an amp but is is then too loud for either the audience or the rest of the band (or even yourself). An amp shield is just a way of naturally attenuating the volume. I would imagine they are all designed to not alter the tone.
I need my Katana to be as loud as it will cleanly go on stage if I'm going to use it as my live amp. A shield would be the last thing I would want.
|
|
