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I have a crate Bass amp that is generating a distorted signal from the imput instrument and it will not clear up :what may be causing this condition on this unit?? Cc:Perplexed!!

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Without hearing the distortion, it will be difficult to state with any confidence where in the amp the problem exists. That being said, the most common problem is with the preamp section. Many of these use 4558 chips as the pre-amp section. If hte chip is blown, the sound may still be heard, but it will be distorted. This is easily seen on a scope. The chips can be purchsed in bulk for les than $1, so the parts cost for the repair should be low.
Dan

Posted on Jun 06, 2008

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I have a vsx-821-k reciever and cant adjust the bass


If the treble is good and is working then the failure to adjust or increase bass output even when it is done can be due to faulty OP-AMP in the BASS circuit. The BASS frequency must be enhance with an amplification and a pass filter with amplification boost and so a failure of this stage can be the reason for non action.You will need to have a signal test on the bass section to confirm the faulty IC.Check for poor solder joint and faulty capacitors/controls.

Dec 14, 2011 | Audio & Video Receivers

2 Answers

Can I use front preouts for subwoofer?


First, you have to have a self-powered subwoofer (or two) with this reciver. That means the sub has its own amplifier. These are usually capable of accepting either Line Level (RCA) input or direct L and R amplifier channel speaker wires from your receiver from which it will react only to frequencies in its range. It doesn't actually use any if the power from your receiver's amp.

That is why you can extend your front speakers from the sub. Again, understand this - it is not playing any part in amplifying them. The amps in your receiver are just passing through it.

Setting your speaker 'Type' definition to Large will tell your receiver that they are capable of real bass (as opposed to small satellites) but won't necessarily steal anything from the subs. Set your LFE/Bass Out setting to Both if your front speakers are capable of handling real bass. Why would you want to deny them bass if they can handle it?

This part is confusing "If I can get the sub working on taking the lows out of the front speakers if I set them to large on the receiver then that is one thing less to send to the other sub on the LFE channel". The crossover feature allows you to define what bass goes to the sub. You would use the various points to smooth out the transition between your sub and the rest. Your quote of 47hz spec for something doesn't suggest your other speakers are great bass reproducers. One needs to see the +- db spec with less than x% distortion for that number make any sense.

Your receiver has two RCA Subwoofer Outputs but I'm sure they get the exact same level. If you're having trouble matching two different subs doesn't at least one of them have an adjustment for volume? Or maybe you could use physical positioning to adjust their comparative volume.

May 08, 2009 | Yamaha RX-V663 Receiver

1 Answer

CRATE PA-B6350 no output


The 2 speaker jacks are wired in parallel. If your subs are 4 ohm rated the amp is seeing a 2 ohm load and may be trying to protect itself - hence the red light. I would suggest you unplug 1 of the subs and see if the problem goes away. You may have a problem with one of your subs. This amp is probably not the best choice for such demanding work as it is not fan cooled. Good luck.

Feb 21, 2009 | Onkyo TX-NR905 Receiver

1 Answer

I have a crate BX 160 that shuts down at the point where it starts limiting and then after a about 30 seconds. it starts back up. I would like to get a schematic on this particular piece of equipment...


I just saw your post. I happen to have a Crate BX-160 and was able to call Crate in St. Louis and talked with a tech there at the plant and he actually sent me full schematics for free.

Your problem, based on my electrical background and fixing audio equipment for 10 years, seems to be related to the built-in limiter in the power transformer. In other words, you might just need a new power transformer and it is a piece of cake to install (all push-on connections).

The schematic will show you the many test points for voltage checks, but unless you know what you are looking for, its just information overload. It is a rather simple amplifier and built resonably well. I have been using mine since 2003 and have fixed it a few times (age related problems like loose connections). There just is not much to go wrong on them except for the fact the amp is subjected to extream vibration. THis causes physical connections to fail resulting in vexing issues that are hard to solve. This is not unique to this amp (all bass amps).

I would bet anything your problem is the power supply shut-down circuitry is malfunctioning. In my expereience with amps, unless the amp is drawing current (failing power circuitry) and making strange sounds, the failure is usually not related to the power section failing (like power transformers going out). Likely, the built in limiter is the problem.

I hope this helps!

-mike
(development engineer)

Jan 20, 2009 | Audio & Video Receivers

1 Answer

No sound out of the Amplifier.


hello if you not even heard a low buzz en the speakers with all volume up is probably burned take it to rapier shop for a estimated saludos

Jan 08, 2009 | Audio & Video Receivers

1 Answer

I want to get the metallica sound from my marshall AVT50


Use the high gain channel. Set the bass to 8-10 set set the mids to 6-7 and the treble to taaste to cut through. Also turn the contour all the way up. To gice that scooped mid sound. Or use the celan channel on the amp and run a boss metal zone pedal through it. Set amps clean channel EQ to flat ( at 5) and the metal zones controls. Treble to taste for a good bite, bass up to the point were it wont fart out on your amp, sweep the mids outer knob set about 5-7 and the inner knob to about 4. Set prescence for clearity and the distortion level as high as you can stand it.

Aug 19, 2008 | Audio & Video Receivers

1 Answer

I have this pioneer receiver model VSXD608 in which when the volume goes below 20db the unit goes in protection and after some time it tries to switch on back but goes to protection again and keeps on...


Check to see that the electrolytic capacitors that are in the output stage circuits and driver stage circuits are not high in ESR.

Check to see that the power supply is in specs. The main electrolytic caps may not be up to specs. To test the power supply it is best to run a load test on it. You will need the proper setup for this.

The supply current to the output stage may be high, and thus causing the protection to turn on. You will need to have the service manual for details.

It is also possible that the speakers are too low impedance, or their crossovers are going defective and causing a miss-match for their loading impedance.

Look with a scope to see that there are no high frequency oscillations in the output of the amp going to the speakers. A common cause of this type of fault are worn de-coupler caps in the bias circuits for the various stages along the signal path.

Check to see that there is no DC out to the speakers with any position of the volume control with no signal going in. The speakers must be disconnected for this test. Do the same with a sine-wave signal from the test generator. 1 kHz is good to use for this test. Use a proper rated 8 ohm dummy load for your amplifier when applying the test signal. Do not put steady strong tone in to your speakers. You will have to refer to the service manual to know the allowable DC offset at the output stage to the speaker terminals. Most consumer amplifiers must be less than 50 mv. The higher end amplifiers are down to less than 10 mv.

It is also good to do a distortion test to see if there is too high a distortion that is causing the protection to trip.

You can also use the dummy load and the audio generator along with the scope to do power handling tests. This gets involved to put over this type of email.

These are only some basic examples of what to check. You will need the service manual, a scope, ESR meter, DVM, audio generator, and distortion analyzer to go through all the tests to find out where the fault is.


Jerry G.


Jul 07, 2008 | Pioneer Audio & Video Receivers

1 Answer

Crate VC6212 Amp


Yes the tube could be what is called microphonic. In other words it behaves like a mic and feeds some signal back into the amp. These are usually 12ax7 tubes and are not expensive. Start with replacing that tube.
Keep us posted.
Dan

Apr 07, 2008 | Audio & Video Receivers

1 Answer

Receiver amp problem?


You are having problems with you audio amps, 1 or more are going out. will need to change using part number on amps. you can order from, Bluestar-online.***, VanceBaldwin.***

Oct 04, 2007 | Audio & Video Receivers

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