Hi-Z Instructions On Big Al

[cassius987]

I noticed each time I went to GC to check out the same Big Al (really tempting bass by the way), it has a "Connect this instrument to Hi-Z input only", kind of warning near the input jack. Just curious--doesn't this advice apply not only to every MusicMan bass, but also to the vast majority of basses made? I wonder what the impetus was to suddenly apply this warning exclusively to the Big Al when it seems like people should have gotten up to speed on this issue decades ago. What's up? I know these are active basses but still you would think most people are going Hi-Z with their amps, etc. Or maybe I just answered my own question--is this the only EBMM bass capable of going passive via the VT circuit?

By the way, I don't own any EBMM instruments at this time (Mr. Al is drawing me back to the fold though), so if this is a totally out-of-the-loop question I apologize.

 

[Grand Wazoo]

It's meant to say that with the on board 18V preamp, if your amplifier is provided with 2 input sockets one "passive" the other "active" you should connect this bass to the active input. If your amp only has one input then you must adjust the gain level accordingly, i.e. keeping it below clip and that is achieved by keeping your bass at full volume and making sure the input level stays clean and does not break into distortion, unless of course you do want to have a distorted sound.

 

[oli@bass]

The Big Al, the 25th, and the upcoming Reflex have a preamp that can be bypassed so that the instrument ist actually passive. While it is possible to connect instruments with preamps to inputs that are actually not designed for instruments (like going direct into line level inputs at mixing consoles) with good results, this does not work properly for passive instruments which require a high impedance input for to work correctly.


AFAIK

Here some Wikipedia insight on the topic:
High impedance - Wikipedia, the free encyclopedia

"In analog circuits a high impedance node is one that does not have any low impedance paths to any other nodes. High impedance nodes have high thermal noise and are prone to pick up. They are also often difficult to probe as the impedance of a scope can load down the node. High impedance nodes are useful in amplifiers as they allow for large voltage gains without large current consumption."

 

[Big Poppa]

Its the same reason why they tell you not to operate heavy equipment drunk. Warn you the the stove is hot. Advise pregnant women to not take acid. You have to state the obvious to the outside world.

 

[RobertB]

I don't even know what any of this is in reference to ... but I do understand myself a little better now ... (Mom was a 60's flower child).

 

[projectapollo]

Works without batteries, right?

Here is my understanding of the issue. The 25th and Big Al are the first basses to provide both active and passive modes. By passive, I understand that they work even without batteries!! Truly passive, not just an EQ-bypass switch. So, to keep the gain reasonably level when one swithces from passive to actice on the fly, it looks to me like the active signal level has been trimmed back somewhat from your other all-active music man basses. Thus the Hi-Z label. Always plug these basses into the "passive" input of one is provided, that is what is intended by MM. I had a 25th for a while and its ouput was definately considerably less hot than the Bongo. OK, I think I just contradicted some folks, here, so let me know what I have wrong.

 

[RobertB]

My take is this - when playing a bass that has both active and passive circuits/modes (and you plan to use 'em both), you want to pad your active signal so that there won't be a huge difference in your active & passive signal levels when you switch between them, making you sound like a noob on stage, at practice, or in the studio.

Brandt says basically the same at 1:50 in this very cool 25th HH review

 

[cassius987]

So who's using the passive circuit with the Big Al with good results? I neglected to demo it for too long at GC any of the times I was playing the lovely beast. The 4-band pre is my favorite MM pre so I pretty much sat admiring it the whole time, in addition to the cool pickup switch system.

 

[cellkirk74]

I did notice distortion problems when I used the passive input option on one of my amps with the Big Al. Especially the serial setting has an rather hot output in both active an passive mode.

I have a -10db pad knob that does it just right. In general lower output is not a problem at all. That's why bassamps have volume knobs.

 

[Rick Auricchio]

A high-impedance ("Hi-Z") input causes less loading of the bass signal; this loading can cause loss of volume or loss of top end.

Active basses are able to easily drive lower impedance loads, so they're rarely affected by this.

A passive bass, however, really needs a hi-Z input to prevent loading down the signal. Since the Big Al allows passive operation, you might be disappointed if using a lo-Z input on an amplifier.

BTW, my DD2 Big Al sounds just fine in passive mode. And the output is about the same level in either mode. So far, I'm liking passive mode better.

 

[Stereo_Monkey]

So who's using the passive circuit with the Big Al with good results?

Me, Sir! Actually passive is the on and only mode that I am running my two Big Al basses in...

 

[sitonmybass]

Since I own a Bongo 5 HH, Bongo 5 single H, Sterling 5 single H and a Big Al 5 single H, I noticed that the Big Al 5 single H had less output than the other three basses and I must admit that I was disappointed upon discovering this.

I should mention that I've only been using the parallel/active mode; it's a very clear sound and a little closer to what I'm used to using with my other EBMMs but it seems to have a lesser output.

 

[Movielife]

So if an amp has high and low gain inputs, the Big Al goes into the high?! Two different answers above.

 

[projectapollo]

So if an amp has high and low gain inputs, the Big Al goes into the high?! Two different answers above.

Hi-Z, which is low gain.

 

[koogie2k]

Its the same reason why they tell you not to operate heavy equipment drunk. Warn you the the stove is hot. Advise pregnant women to not take acid. You have to state the obvious to the outside world.

A stove gets hot?? Time to warn my beloved....hahaha..


Yeah...some people may not know and a "warning label" may help. Good idea really. Hopefully it cuts down the CS calls. Who knows....certainly not I.

 

[Movielife]

Hi-Z, which is low gain.

Ah right, that makes sense!