I just got my system and am trying it out in the basement, first. I did experience slight feedback when the unit was directly behind me about 12 feet or less. Granted, the real test will be at the gig. But this brings to mind my question on using my feedback exterminator, which has served me well in the past, but figured I'd never need it again with PAS. I'd rather not anyhow. I realize professional sound guys are "embarrassed" to use such a device, but it has helped in the past. What are your thoughts if a person used a feedback killer?
Original Post
Because the amplifier is in the Power Stand, and the feedback eliminator has to be in the signal loop to detect feedback so it can work, the only place you could probably put it so that it would have a chance of working is in the insert loop of one of the channels, which won't help you if the feedback isn't coming from that channel.

I'd rely on gain-staging and judicious use of the EQ on the remote to deal with feedback. I've only ever had minimal problems with feedback in the four systems I use in my band, and my guess is the feedback elimination within the PAS will probably serve you better then an external system which probably won't be patched into the most effective spot to be useful.

Just my $.02...
Hi KC,

If you follow the mic technique and gain staging directions we've given here, you will not need this device. You will get loud and clear vocals without feedback.

Please review the instructions for setting the trim level on Channel 1 and 2. Sing as loud as you're going to sing with your lips touching the windscreen and adjust the trim so that the LED just flickers RED. (You can do this with the channel and master volumes on the remote turned all the way down.

Remember that when you want to be your loudest vocally, you're lips should be touching the windscreen. You can always "work" the mic by backing away from it to lower volume but always remember that when you need to be loudest, you're kissing that windscreen.

This technique is true for ANY live amplification system, not just ours.

Please stay in touch with us here and let us know how you, er, well, make out.

Ken
I have reviewed the gain staging notes from Bose. I did forget to mention that I am using preset 0, as everything is going to Yamaha 01V, then to PAS. So, I am unable to select the PAS preset for my EV457 mic. I am on the verge of feedback just in basement and dial it down to avoid. But at gig I know I'll need more gain on the mic channel. I am having a difficult time zeroing in on the culprit freq with the 01V channel EQ, though I think the 01V is pretty versatile in that respect ( narrowing the Q, then sweeping to find problem freq. But at that point, the freq exterminator ought to be able to exact a thinner band to nail the problem. though I'd rather not add more to the chain...haven't tried it yet though.

question2: I noticed the Bose documentation recommends un-hooking the B1's if you choose to use external bass amp. does this mean trouble if you continue to run the B1 bass mods AND an external amp and spkr for bass?
Hi KC

quote:
Originally posted by KC:
I have reviewed the gain staging notes from Bose. I did forget to mention that I am using preset 0, as everything is going to Yamaha 01V, then to PAS. So, I am unable to select the PAS preset for my EV457 mic.


Try the EV457 mic direct into Channel 1 or 2 with the appropriate preset. If you like the sound better, just leave it running separate from the mixer.
- Or -
you can still use the mixer but route the mic to one of the 4 busses and then route that buss to Channel 1 or 2.

quote:

I am on the verge of feedback just in basement and dial it down to avoid.

Unless you have a really big basement, you are probably more prone to feedback in that environment than you will be at a gig. The walls (and the reflections) are a lot closer than they will be at a gig.

quote:

But at gig I know I'll need more gain on the mic channel. I am having a difficult time zeroing in on the culprit freq with the 01V channel EQ, though I think the 01V is pretty versatile in that respect ( narrowing the Q, then sweeping to find problem freq. But at that point, the freq exterminator ought to be able to exact a thinner band to nail the problem. though I'd rather not add more to the chain...haven't tried it yet though.

That's a lot of work for a problem that may go away when you get out to a gig.
quote:

question2: I noticed the Bose documentation recommends un-hooking the B1's if you choose to use external bass amp. does this mean trouble if you continue to run the B1 bass mods AND an external amp and spkr for bass?


It could well be there but, I don't remember reading that in the documentation. There is mention that removing the B1 changes the frequency response with the L1. If you have something connected to the Bass Line Out, the EQ for the L1 should be the same as when you are using a B1.

I don't think there is any reason to disconnect the B1s if you are going to be using the Bass Line Out.
Hi KC, Hi Steve.

I think I may have found what you were reading. It's on the support site:


Can I use the PS1 Power Stand’s "Bass - Line OUT" with my bass amplifier and cabinet?

The "Bass - Line OUT" connector provides a flat 40 Hz to 180 Hz bandpass signal when no B1 bass module(s) are used with the PS1. We recommend unplugging the B1 bass module(s) to ensure correct EQ compensation of the "Bass - Line OUT" jack as well as phase consistency.


Why does the sound coming from the L1 Cylindrical Radiator® loudspeaker change when plug in a 1/4-inch plug into the Bass–Line OUT connector?

The L1 Cylindrical Radiator™ loudspeaker receives its audio signal from the PS1 power stand. The signal is customized by the internal DSP unit in accordance with what other devices are connected to the PS1 power stand such as how many B1 bass modules and/or amplifiers are connected to the Bass-Line OUT connector. The L1 Cylindrical Radiator™ loudspeaker when used alone with the PS1 power stand produces audio in the range of 110 Hz to 15 kHz. When the Bass–Line OUT connector is in use the frequency cutoff point is moved from 110 Hz to 180 Hz, it will not play any frequencies below 180 Hz. The Bass–Line OUT connector sends a flat bandpass signal from 40 to 180 Hz to external amplifiers that may be used for extended low frequency reinforcement.



So,
Point One
Disconnecting the B1s is to avoid phase issues. You can hear the problem if it exists and remedy it. I remember now that Hilmar-at-Bose posted something about this and I'll see if I can find it.

Point Two
Whether you use the Bass Line Out or connect a B1 (or 2 of them) the EQ changes for the L1s.


There is something strange going on with the second link and I'll report this to the People-at-Bose.
About being Out of Phase:

Although he is talking about using an external amp to drive several B1s, the principles should be the same.

Hilmar-at-Bose wrote
quote:

"There a few things to consider: Please make sure that everything is in phase (some power amps do phase reversals). The easiest way to check that is to build 2 stacks of 2 B1s about a foot or two apart. Run the left stack with the PS1/AMP3 and the right stack with the Crown. Its probably best to NOT insert the L1 Cylindrical Radiator(tm) Loudspeakers for this test, so you will only listen to the bass signals (its perfectly safe to run without the L1). Put your head in between the stacks. If its sound hollow, soft, vague or anemic, then something is probably out of phase. If it's tight and focused, it's in phase.
The other thing is level. The power amp should be set to about 30 dB of gain. I found the Crown specs not particularly helpful, so you might have to do it by ear or measurement. For the "ear" method use the same setup as for the phase check. Run both stacks intentionally out of phase and then dial in the level of the Crown so that the level between the stacks is minimal or the signal disappears completely. The flip the phase back to normal."

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