portaflex/B15 users. rattly cabinets?

[joninc]

hey all - i have professed my love for the ampeg fliptops many times for recording bass and i actually got one in a trade on some work i was doing. it's not the same model i had used previously but in the same family. it's the B15s. (it's unusual in that it's high watts - 100 watts.)

here's the deal - the cabinet rattles insanely if i try to turn it up above like 3 (using a bass through it). bad news for recording. i can obviously run it lower but there are times when i'd love to juice it up a little more.

we were trying to use it for rehearsal the other day (not overly loud players at all - in a small room) and it was farting out and really not useable.

it helps if i take the head off it for recording but i was designed to be used with the head on it correct? (plus the cable attached to the head is too short to have it very far away - i need to get a long one put on)

is this normal? got any tricks? do you guys use different cabs wit yours? should i be getting a new speaker?

i have recorded this same head through a big 8 x 10 cab and it sounded amazing so i am pretty sure the head itself is not the issue here.

[newfuturevintage]

take it apart and put it back together, with an emphasis on getting everything on tightly. Might need to buy the weird headed screwdriver to do so, but fliptops.net sell it for $7.

My SB12 rattled pretty badly over a certain point, but just tightening the chassis screws took care of it.

and yep, designed to be run with the head in place. silly question: does the cab still have the latches to hold the head down?

[joninc]

yep - still has the latches.

[A.David.MacKinnon]

God I love those things for recording bass and clean guitar. So good.

As suggested above, tighten the shit out of everything and maybe put some tape over the latches as well just to dampen any vibrations. Also, there's no harm in taking the head off the cab for recording if it makes this usable. No-one will know and if they ask you can lie.

Enjoy. I wish I had one. My next best thing is an early silver-face Super Reverb.

[calaverasgrandes]

My GK 4x12, 2x10 (in one cab) used to rattle like hell.
I I took it all apart and put it back together with more insane hardware (stainless steel bolts) and rewired it with heavier guage wire. It sounds awesome now. But then it has lived in my home theater as a sub for a year now!

[teleharmonium]

You might save yourself some trouble by taking a piece of plastic tubing, putting one end in your ear and moving the other end around the amp while looping something through it to help localize the buzz.

There are long screws and washers stuff that hold the head chassis to the removeable plate on the top of the amp; those can get loose (they're adjustable in order to control the chassis height, which also means they can move over time) and buzz. Also there's probably a double baffle where the speaker is mounted, you might find that the screws there need to be tightened. Or it could be the speaker is loose on the baffle, or was previous made overly tight and is now warped and causing the rattle. Another possibility is that the speaker gasket has partly disintegrated and the speaker is still working but doing weird things.

If you have the dolly, take the amp off the dolly to remove the wheels and coupling of those two things from the equation.

There's gasket material that is supposed to stick out slightly in order to compress and make a seal on the top of the cabinet where the head plate goes on; it can get crushed over the years so it no longer works, or it might have been removed after it started to look crappy. You can replace that if need be.

[joninc]

ok - so i did some further hunting and chasing of the buzz today.

i discovered that there was a little bit of a loose screw around the speaker in one place that was causing it to vibrate against the cabinet and make a rattle. i tightened it and that sound went away.

then i experimented with playing with the head on or off the cab.

i do get a lot of additional rattling when the head is on the cabinet. i can't really explain why - i don't believe the rattling is coming FROM the head itself (i mean acoustically/mechanically) but as a result of putting the head in place - i get a real noticeable amount of noise. somehow it's transferring through the electronics/tubes or something?

AHHH! that is really annoying! i can't really see how this is something i can fix.

any further thoughts?

[@?,*???&?]

hey all - i have professed my love for the ampeg fliptops many times for recording bass and i actually got one in a trade on some work i was doing. it's not the same model i had used previously but in the same family. it's the B15s. (it's unusual in that it's high watts - 100 watts.)

here's the deal - the cabinet rattles insanely if i try to turn it up above like 3 (using a bass through it). bad news for recording. i can obviously run it lower but there are times when i'd love to juice it up a little more.

we were trying to use it for rehearsal the other day (not overly loud players at all - in a small room) and it was farting out and really not useable.

it helps if i take the head off it for recording but i was designed to be used with the head on it correct? (plus the cable attached to the head is too short to have it very far away - i need to get a long one put on)

is this normal? got any tricks? do you guys use different cabs wit yours? should i be getting a new speaker?

i have recorded this same head through a big 8 x 10 cab and it sounded amazing so i am pretty sure the head itself is not the issue here.

Farting sound? YEAH. AWESOME. Plug a guitar into it- something like a Telecaster, front pick-up. Record another version of "To Bring You My Love". F---in awesome. And PJ is so GODDAMN HOT...

Problem? Nope.

Ooops, for bass? It's a B15. What's the problem?

Just don't record all day with it at temperature and expect it to sound the name next day- after a nights cool down. Fussy, with a capital 'S' and Awesome with a capital 'A'.

[Jim Williams]

Get some white glue and a hypo and reseal all the wood joints. Then air seal them with silicon glue.

The joints can work loose after so many years. They wern't made that great so it's a good idea to redo all those wood joints. After 24 hours, use silicon calking like for the bath. That will seal any air leaks. Check for leaks with a lighter flame while playing low E. Don't melt the tolex.

Glue down all loose caps inside the amp. Reset the tube sockets by tightening the pins or just replace them with ceramic sockets.

Remove all stuffing from the speaker cab. Order 4 DeFlex round panels from
www.michaelpercyaudio.com

Use silicon glue and mount them on the sides of the cabinet. That will damp better than stuffing and will eliminate cabinet resonance, that "boxy" sound. They also increase bass output.

You will be impressed!

[teleharmonium]

any further thoughts?

see my post above. Have you checked the gasket on the top of the cabinet where the head plate goes ?

[joninc]

jim - thanks for the thoughts - but can i ask further: how do you think the head is affecting this issue?

when it's off the cab - it's not rattling anymore but there is nothing obviously loose in the head. the tubes are all secure - no loose screws etc.

the rattling i hear when it's on the cab is not emanating from the head or out of the speaker - it's coming from inside the cab - somewhere in the back i think.

i wonder if it's just that the head is creating a seal for the cab adding to the air pressure on all the seams etc.. of the cab?

maybe i should just get a longer cable for my head and deal with having it off the cab? is there any tonal issue with having the cab open on the top? would the sound be more focussed if the head were on and nothing rattled?

[joninc]

any further thoughts?

see my post above. Have you checked the gasket on the top of the cabinet where the head plate goes ?

i am not sure if i understand what you mean.

is this a part of the head - or the cab?

EDIT: i reread your post - i am thinking we are talking about the head now.

ok - i looked at the head but i am not sure how to take it off the plate - is it those (horizontal) outside screws that need to be undone?

[teleharmonium]

any further thoughts?

see my post above. Have you checked the gasket on the top of the cabinet where the head plate goes ?

i am not sure if i understand what you mean.

is this a part of the head - or the cab?

EDIT: i reread your post - i am thinking we are talking about the head now.

ok - i looked at the head but i am not sure how to take it off the plate - is it those (horizontal) outside screws that need to be undone?

It's on the cabinet. The head is mounted to a wooden plate which is where the 4 luggage clips are holding it down; if you look at the top of the cabinet, the rectangle formed by the top surface of the cut out area where that plate goes on top of the cabinet, has this gasket (or at least would have had it originally). It should protrude a little bit above the wood, so that it absorbs vibration so that less vibration is transferred to the head.

[joninc]

ok - i checked that - it's definitely flattened right down and is not protruding at all.
i should replace this - i think that would help with vibration/transferance etc...

any idea what to use to replace it with or where to obtain a material like that?

[teleharmonium]

ok - i checked that - it's definitely flattened right down and is not protruding at all.
i should replace this - i think that would help with vibration/transferance etc...

any idea what to use to replace it with or where to obtain a material like that?

I got mine from here -

http://www.fliptops.net/catalog/product ... cts_id=506

-although it seems like the sort of thing that you might be able to get from a hardware store for less if you knew the right name for it. It's just rubber gasket material with a thin strip which slides down into the rectangular slot to hold it in place, and then a fatter lip on top to do the cushioning.

Also, the latches themselves play a role, over time they tend to get angled so that they aren't adding pressure any more. Especially if your amp has no side handles and it has been moved in the past using the top handle only with the chassis in the inside position, putting the entire weight of the amp on those luggage latches.

If they move easily, you might consider putting some superglue and wood dust into the screw holes with a toothpick to make them tighter and then reinstalling them.