Crate Amplifiers Rear Panel, To Eliminate Instrument Feedback, CA60 Block Diagram, Not Shown

On the

Rear Panel:

		Line Outputs			Effects		Foot
					Loop		Switch
0	10							Off
Level		Low Z	High Z	Gnd	Return	Send	Reverb/
				Lift				On
		Bal.	Bal.				Chorus	Tweeter
	33	32	31	30	29	28	27	26

26:Tweeter On/Off swtich. This switch, when depressed, deactivates the CA60’s internal tweeter.

27:Footswitch. Connect the supplied two-button footswitch here for remote on/off control of the internal reverb and chorus. (When connect- ed, the footswitch overrides the front panel chorus on/off switch.)

Note: This is a STEREO jack: tip controls the chorus, ring controls the reverb, sleeve is ground. Use only a footswitch equipped with a stereo 1/4” plug.

28:Effects Loop Send. When using an external signal processor, connect this jack to the input of the effect by means of a shielded signal cable.

29:Effects Loop Return. When using an external signal processor, connect this jack to the output of the effect by means of a shielded signal cable.

30:Ground Lift. This switch, when depressed, electronically disconnects the low Z balanced output jack’s chassis ground connection. If you expe- rience excessive noise when using the low Z balanced output jack, depress this switch.

31:High Z Bal. Use this jack to connect a high impedance, line level signal to a house sound board, a recording console or an external power ampli- fier by means of an 1/4” stereo plug-terminated cable. (Ring is signal +, tip is signal -, and sleeve is ground.)

32:Low Z Bal. Use this jack to connect a low impedance, line level signal to a house sound board, a recording console or an external power amplifi- er by means of an XLR-terminated cable. (Pin 1 is ground, pin 2 is signal +, and pin 3 is signal -.)

33:Line Out Level. Use this control to adjust the output level of the line out signal. (This control works independently from the amplifier’s master level control.)

Not Shown:

Power cord. Connect the end of this cord to a suitable source of line volt- age. Refer to the voltage information on the back of the amplifier for its voltage and current requirements.

Note: This is a grounded plug. To avoid the possibility of electric shock,

DO NOT defeat the ground connection in any way!

To Eliminate Instrument Feedback:

One of the most common problems encountered when amplifying acoustic instruments, especially in small environments, is feedback. Acoustic instruments typically have inherent qualities which cause res- onant feedback at specific frequencies. Instrument tone controls and sound board equalizers are helpful in getting rid of the problem, but they typically operate around relatively wide frequency bands. This almost always means the musician must sacrifice sound quality in his quest to do away with feedback. But since Crate’s feedback elimination circuit isolates only the offending frequency, instrument feedback from the CA60 can be eliminated without affecting the overall sound.

Chances are, you may not have a problem with feedback at all. In that case, set the CA60’s Freq and Cut controls fully counter-clockwise. However, if you do encounter feedback while playing, set the Cut control to -30dB (fully clockwise) and adjust the Freq control until the feedback is gone. Reduce the Cut to the 12 o’clock position and readjust the Freq control as needed. Continue reducing the Cut control and readjusting the Freq control until there is no more feedback with the Cut control as far counter-clockwise as possible. This approach effectively eliminates instrument feedback without sacrificing the quality of your sound.

CA60 Block Diagram:

left right

effects line out

instrument

channel

input

active piezo

phantom power

low-z vocal/aux input channel

hi-z input

filter		tones	chorus		chorus
			rev/	on
			effect
			send
freq cut	gain	low mid high	shape		depth rate
			peak
		rev/
		effect		on
		send	chorus
	tones
gain	low	high	effects
			return

on

line out

level

effects send

spring reverb	reverb
	return
		high pass
		filter
	tweeter	high
hi-z	on/off
bal.

		right	low
low-z
			30w
bal.	master
	level
		left	low
			30w