"Active/Piezo" button on Crate CA-125 acoustic guitar amplifier

[Jonathan]

I have an approximately 20 year old Crate CA-125 acoustic guitar amplifier, and next to the input jack is a button that says "Active/Piezo." I have always been curious what this button does. Does anyone here know?

Here is what the manual says:

Active/Piezo switch. Use this switch to select the type of pickup on
your instrument. For active electronic pickups, set the switch to
“active” (switch out). For passive/magnetic pickups, set it to “piezo”
(switch depressed).

Thanks,
Jonathan

[RichL]

"Jonathan" <gosto.d...@gmail.com> wrote in message
news:0f20f3e1-6ee4-41d8...@googlegroups.com...

Basically it's changing the input impedance (higher for piezo pickups, lower
for active) and input sensitivity.

[Jonathan]

On Sunday, November 18, 2012 7:04:36 PM UTC-5, RichL wrote:
> "Jonathan" <gosto.d...@gmail.com> wrote in message
>
> news:0f20f3e1-6ee4-41d8...@googlegroups.com...
>
> > I have an approximately 20 year old Crate CA-125 acoustic guitar
>
> > amplifier, and next to the input jack is a button that says
>
> > "Active/Piezo." I have always been curious what this button does. Does
>
> > anyone here know?
>
> >
>
> > Here is what the manual says:
>
> >
>
> > Active/Piezo switch. Use this switch to select the type of pickup on
>
> > your instrument. For active electronic pickups, set the switch to
>

> > �active� (switch out). For passive/magnetic pickups, set it to �piezo�

>
> > (switch depressed).
>
>
>
> Basically it's changing the input impedance (higher for piezo pickups, lower
>
> for active) and input sensitivity.

Interesting. How come the more modern acoustic guitar amps like the Fishman Loudbox, Fender Acoustisonic, and California Blonde no longer seem to have this switch?

Thanks,
Jonathan

[RichL]

"Jonathan" <gosto.d...@gmail.com> wrote in message

news:bb74d965-6be5-4903...@googlegroups.com...

> On Sunday, November 18, 2012 7:04:36 PM UTC-5, RichL wrote:
>> "Jonathan" <gosto.d...@gmail.com> wrote in message
>>
>> news:0f20f3e1-6ee4-41d8...@googlegroups.com...
>>
>> > I have an approximately 20 year old Crate CA-125 acoustic guitar
>>
>> > amplifier, and next to the input jack is a button that says
>>
>> > "Active/Piezo." I have always been curious what this button does. Does
>>
>> > anyone here know?
>>
>> >
>>
>> > Here is what the manual says:
>>
>> >
>>
>> > Active/Piezo switch. Use this switch to select the type of pickup on
>>
>> > your instrument. For active electronic pickups, set the switch to
>>

>> > �active� (switch out). For passive/magnetic pickups, set it to
>> > �piezo�

>>
>> > (switch depressed).
>>
>>
>>
>> Basically it's changing the input impedance (higher for piezo pickups,
>> lower
>>
>> for active) and input sensitivity.
>
> Interesting. How come the more modern acoustic guitar amps like the
> Fishman Loudbox, Fender Acoustisonic, and California Blonde no longer seem
> to have this switch?
>
> Thanks,
> Jonathan

I'm just guessing, but I think it's because most modern "electrified"
acoustic guitars have piezo pickups or microphone pickups that are
compatible with the input impedance and sensitivity that correspond with
piezos.

[Tony Done]

- Because the great majority now have low impedance preamps in the
guitar. The amps mentioned might not sound good with a passive piezo
going into them; tinkerers such as myself would assume that if the
guitar didn't have a preamp it would be necessary to have one between
the guitar and the amp.

--
Tony Done

http://www.soundclick.com/bands/default.cfm?bandID=784456
http://www.flickr.com/photos/done_family/

[JJTj]

On Sun, 18 Nov 2012 20:43:34 -0500, "RichL" <rple...@yahoo.com>
wrote:

>>> Basically it's changing the input impedance (higher for piezo pickups,
>>> lower for active) and input sensitivity.

That's about it, maybe a small trim cap too but esp a Create, who
(exp back then) did it on the cheap. Other companies may of used
a sep op amp (or trans) gain stage, but in this amp, I'd guess a res.

>> Interesting. How come the more modern acoustic guitar amps like the
>> Fishman Loudbox, Fender Acoustisonic, and California Blonde no longer seem
>> to have this switch?

>> Thanks,
>> Jonathan

>I'm just guessing, but I think it's because most modern "electrified"
>acoustic guitars have piezo pickups or microphone pickups that are
>compatible with the input impedance and sensitivity that correspond with
>piezos.

Also, a 'happy medium' was found. Remember, a switch and a knob
cost $$, and companies constantly find ways to cut corners. ESP in
that time frame. Cheaper then a knob (to adjust the imp) is a switch
(to switch it from a to b), then comes a sep jack pre-wried one way.

Glad to see some on-topic posts here for a change...

JJTj

[Jonathan]

What are the consequences (sonic or otherwise) if the impedance between the instrument and amplifier are mismatched? Is it possible to harm either, or will it just sound bad?

[Neil Gould]

I think it's the opposite... most modern amplifiers have higher input
impedances, making them more compatible with piezos, stomp boxes, etc. while
still working well with magnetic pickups.

--
best regards,

Neil

[jh]

Am 19.11.2012 16:01, schrieb Neil Gould:
> RichL wrote:
>> "Jonathan"<gosto.d...@gmail.com> wrote in message
>> news:bb74d965-6be5-4903...@googlegroups.com...
>>> On Sunday, November 18, 2012 7:04:36 PM UTC-5, RichL wrote:
>>>> "Jonathan"<gosto.d...@gmail.com> wrote in message
>>>>
>>>> news:0f20f3e1-6ee4-41d8...@googlegroups.com...
>>>>
>>>>> I have an approximately 20 year old Crate CA-125 acoustic guitar
>>>>
>>>>> amplifier, and next to the input jack is a button that says
>>>>
>>>>> "Active/Piezo." I have always been curious what this button does.
>>>>> Does
>>>>
>>>>> anyone here know?
>>>>
>>>>>
>>>>
>>>>> Here is what the manual says:
>>>>
>>>>>
>>>>
>>>>> Active/Piezo switch. Use this switch to select the type of pickup
>>>>> on
>>>>
>>>>> your instrument. For active electronic pickups, set the switch to
>>>>

>>>>> ￜactiveￜ (switch out). For passive/magnetic pickups, set it to
>>>>> ￜpiezoￜ

>>>>
>>>>> (switch depressed).
>>>>
>>>>
>>>>
>>>> Basically it's changing the input impedance (higher for piezo
>>>> pickups, lower
>>>>
>>>> for active) and input sensitivity.
>>>
>>> Interesting. How come the more modern acoustic guitar amps like the
>>> Fishman Loudbox, Fender Acoustisonic, and California Blonde no
>>> longer seem to have this switch?
>>>
>>> Thanks,
>>> Jonathan
>>
>> I'm just guessing, but I think it's because most modern "electrified"
>> acoustic guitars have piezo pickups or microphone pickups that are
>> compatible with the input impedance and sensitivity that correspond
>> with piezos.
>>
> I think it's the opposite... most modern amplifiers have higher input
> impedances, making them more compatible with piezos, stomp boxes, etc. while
> still working well with magnetic pickups.
>

...

=:o

[Tony Done]

From what I have read the amp impedance should be higher than the
guitar. - Unbuffered piezos certainly sound bad going into a standard
guitar amp input.

[Tony Done]

Just checked. That certainly applies to the Acoustasonic, input
impedance 10 megohms. Ibanez Troubador not so much, 500K. It would be
interesting to see how they actually work with unbuffered piezos. EQ to
eliminate hardness and quack would also be important.

There are other factors with unbuffered piezos, like cable loss.

[Neil Gould]

A lot depends on the circuit design.

I have preamped piezos in some of my guitars, and I'm currently working with
a set of ST1s that I installed passively in my Dan Armstrong, now a Neil
Armstrong ;-). The ST1s are composite bridge pieces very similar to and
possibly a forerunner of the Graph Tech Ghosts, since I bought them about 15
years ago.

They sound fine that way, and there is no cable loss because I designed the
volume and tone circuit to address the impedance requirements of the piezos.
Naturally, the piezo's output level isn't up to the Armstrong pickup, but
that was to be expected since the DA pickup is the loudest pickup in any
guitar I've played over the last 50 years or so, and they blend together
beautifully, too.

--
best regards,

Neil

[Les Cargill]

It is most likely a pad.

--
Les Cargill

[Les Cargill]

output Z on a preamp is much lower than a naked peizo. Yeah, there's
EQ and all but the main job of a preamp is to buffer it.


--
Les Cargill