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Brief sound cutouts on K2


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#1 Taustin Powers

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Posted 16 May 2006 - 04:50 AM

I am using the K2 as part my bass rig. Setup is as follows:

Read Custom Bass Purity Preamp
Crown K2, bridged mono at 4 Ohm
Eden 410XLT speaker cabinet


At my last band practice, the sound started cutting out for 1-2 seconds at a time about every other minute or so. I am trying to pinpoint where the problem lies - preamp or poweramp. None of the protection LEDs come on, so I don't think it's an overheating or clipping issue. The sound is crisp and clear when it's there, so I don't think I am overpowering the speaker either.

Any ideas of what could be causing these short cutouts in sound?

#2 P. Morrison

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Posted 16 May 2006 - 03:43 PM

bridged mono 4 ohm is just as heavy a strain as stereo 2 ohm. Not many amps can handle that. Try parallel mono instead.

#3 Bud Bolf

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Posted 16 May 2006 - 09:29 PM

Hi Taustin,
WOW, a K2 Bridged at 4 ohms, that is 2500 watts into 1 Eden 410XLT that is rated at 700 watts at 4 ohms!
That's over 3X's the rated cab spec!
Check this out: How Much Power do I Need

You would have been better off with a K1 at 1500 watts Bridged at 4 ohms.
But be that as it is, you could first bypass the preamp and go into the Amp possibly with a DI and see if it still cuts out.
Try and isolate the problem.
I don't imagine that it is the Speaker cab.
Divide and Conquer!
The truth will be shown LOL!
You could always put the K2 into a PA on a Sub or something and push the living daylights out of it!

Good Luck,
     Bud

#4 Taustin Powers

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Posted 17 May 2006 - 03:47 AM

Thanks for the input, guys.

I will switch to stereo mode tonight, and then just use one channel at 800 watts. That way I can try both channels separately to see if there might be a problem there, and it'll be much nicer for my cabinet... wink.gif Next step would be to try a different pre or DI, but that will be harder since I don't have one.

#5 Bud Bolf

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Posted 17 May 2006 - 04:17 PM

QUOTE(Taustin Powers @ May 17 2006, 04:47 AM)
Thanks for the input, guys.

I will switch to stereo mode tonight, and then just use one channel at 800 watts. That way I can try both channels separately to see if there might be a problem there, and it'll be much nicer for my cabinet... wink.gif Next step would be to try a different pre or DI, but that will be harder since I don't have one.


Hi Taustin,
I did some checking on the Read Purity Preamp and it looks like it's a great Preamp!
I could find nothing bad written about it, though that still does not mean that it does not have a problem.
That's why I thought about taking it out of the loop and just trying the Amp.

You can try both channels one at a time and see if either one gives you a problem.

What does Eden recommend for power for your cab?
The reason for the How much Power article above and that you use 1.5 to 2x
the RMS/Continuous rating of the Speaker/Cab is for headroom and the Peaks.
At the same time you need to also be careful of too much power and excessive heat to the Speakers voice coil.
Power within reason.
Too little power causes people to possibly push their amps to hard and hence CLIP!

Is your Eden cab the 4 ohm or 8 ohm version?

Either you can try and isolate the problem yourself or just take your Amp in for a Cleaning and complete check out to see if all Specs out ok.
If it is under Warranty this would be free.

I'm just shooting in the dark here.
You say that:
QUOTE
started cutting out for 1-2 seconds at a time about every other minute or so

What was the Amps status at this time?
If you turned down the Amp would it stop?
The K2's do not have a fan, is it in a hot place, or maybe leave a space open above the Amp.
I have seen posts where people have left spaces free around the Amp in a rack,
and or added a Fan to keep it cool.
This is of course if it is the Amp that is cutting out.
Do you have any other Bass Heads?
If so you could run the Preamp into that amp and just leave all settings at center and see if the preamp cuts out.
When was the last time that you changed out the Tubes in your Preamp?
Contact Read and ask if they have ever noticed a problem like this with their preamps.
Contact Eden and tell them of your setup and see what they think of it.
Everyone has Tech Support and free 800 numbers.
Make some calls and be a detective.

Good luck,
     Bud

#6 Taustin Powers

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Posted 17 May 2006 - 05:22 PM

Thanks for all the input & helpful information!

I just got back from band practice and seem to figured out the problem, although it does not seem entirely logical to me.

First I noticed that during the cut outs the signal led of the Crown would go completely out as well. So, no signal going into the Crown, therefore the speaker is ruled out as the culprit. I then hooked up the preamp to a different power amp, to see if it's the Read that stops sending the signal. Everything worked fine, I played a good 20 minutes straight - no problems. Which would narrow it down to the Crown. Now the next question was, why are there interruptions in the signal input in the Crown? None of the clipping or other warning LEDs were lighting up. At very low volume, it would even sound distorted at times, I noticed. The solution turned out to be turning the output gain of the preamp down to about 10 o' clock. I compensated the loss of volume by turning up the Crown (it's running in stereo, ergo at 800 watts, 4 Ohm now), and bingo! No more problems. I guess the Read has a really high output signal, or the input level on the Crown is set too high (I need to look into that, I bought it used).

What puzzles me: If the input signal was too high for the Crown, shouldn't there have been warning LEDs flashing, instead of just random quiet moments?

Anyways, it seems to be fine now. Thank you very much for your helpful suggestions!

#7 Bud Bolf

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Posted 17 May 2006 - 05:35 PM

QUOTE(Taustin Powers @ May 17 2006, 06:22 PM)
Thanks for all the input & helpful information!

I just got back from band practice and seem to figured out the problem, although it does not seem entirely logical to me.

First I noticed that during the cut outs the signal led of the Crown would go completely out as well. So, no signal going into the Crown, therefore the speaker is ruled out as the culprit. I then hooked up the preamp to a different power amp, to see if it's the Read that stops sending the signal. Everything worked fine, I played a good 20 minutes straight - no problems. Which would narrow it down to the Crown. Now the next question was, why are there interruptions in the signal input in the Crown? None of the clipping or other warning LEDs were lighting up. At very low volume, it would even sound distorted at times, I noticed. The solution turned out to be turning the output gain of the preamp down to about 10 o' clock. I compensated the loss of volume by turning up the Crown (it's running in stereo, ergo at 800 watts, 4 Ohm now), and bingo! No more problems. I guess the Read has a really high output signal, or the input level on the Crown is set too high (I need to look into that, I bought it used).

What puzzles me: If the input signal was too high for the Crown, shouldn't there have been warning LEDs flashing, instead of just random quiet moments?

Anyways, it seems to be fine now. Thank you very much for your helpful suggestions!


Taustin,
What do you have the Input sensitivity set to for the K2.
This is from the Spec sheet for the K2:

QUOTE
Voltage Gain (at maximum level setting): 31.5 dB (K1) or 33.1 dB (K2) with input sensitivity switch set to 1.4V. 26 dB with input sensitivity switch set to 26 dB gain (back panel switchable).


The Read Purity should say what the Voltage Input should be set to.
Also is there a +4/-10 dB setting on the Read Purity?

Glad to hear that it's better, maybe just in the setup of PreAmp to K2.

Later,
   Bud

#8 Bud Bolf

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Posted 17 May 2006 - 06:03 PM

Hi Taustin,
In searching out your Read Purity Preamp I came across this post by you, over at TalkBass:
Taustin Powers Bass

How did the Bass come out, though I see that this post was in 2002 and where is Jack at ReadyCustom?
When I try to pull up www.readycustom.com nothing comes up.
Is his site dead?

Thanks,
    Bud

#9 Taustin Powers

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Posted 18 May 2006 - 02:09 AM

The bass came out pretty much flawless when I received it. Looked gorgeous, played smoothly and a tone to die for. However, over time it has turned out to be somewhat of a problem child. It looks like the woods Jack used hadn't been suffieciently dried out at the time, so they are still in the process of doing that today. This results in a lot of wood warping/shrinking. At some point I wasn't able to set it up properly anymore without getting fret buzz, so I had it plek'd. (www.plek.com) It played very well again, but the luthier also noticed how much the wood had warped already. He filed down the edges of the frets too, that were sticking out the side of the fret board now. About a month later, the electronics in the bass crapped out on me. I took it back to the same luthier, and first thing he noticed was that the frets were already starting to stick out over the fret board again, i.e. the wood is still shrinking. I had to have the cavity cover fixed too, as it wouldn't fit snug anymore (warped). It still looks and sounds incredibly nice, but this whole wood thing left a little aftertaste... And I live in Germany now, so I can't really just take it back to him.

www.readcustom.com has been down for awhile, he hasn't been answering to emails either. From what I hear, he stopped building basses and is going to focus on amps, and he's right now going through a transition phase, or something.

The preamp is awesome btw, and also Jack is a great guy to work with. He did everything in his power to make sure I got the exact bass I wanted. All the more surprising is then that the woods hadn't been drying long enough when he used them. For a guy of his caliber, that is really disappointing.

#10 Taustin Powers

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Posted 19 May 2006 - 02:47 AM

Here is another interesting piece of info I found:

"Transformer overheating (an extremely unlikely event) will result in a temporary shutdown; when it has cooled to a safe temperature, the transformer will automatically reset itself."


Could this what what was happening? What would cause a transformer to overheat?

I did reconfigure the amp to 230v when I brought it over to Europe from the states. However, I placed the jumper cables correctly, replaced the fuse and attached a new power plug. Did I miss something?

#11 DGlass

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Posted 25 May 2006 - 09:25 AM

QUOTE(P. Morrison @ May 16 2006, 03:43 PM)
bridged mono 4 ohm is just as heavy a strain as stereo 2 ohm. Not many amps can handle that. Try parallel mono instead.

The K series will not do a Parallel Mono Mode. Parallel Mono mode was a special output state that our Grounded Bridge topology amplifiers (MA/MT/CT/PB/PT etc) could be placed in.

#12 DGlass

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Posted 25 May 2006 - 09:39 AM

QUOTE(Taustin Powers @ May 19 2006, 02:47 AM)
Here is another interesting piece of info I found:

"Transformer overheating (an extremely unlikely event) will result in a temporary shutdown; when it has cooled to a safe temperature, the transformer will automatically reset itself."


Could this what what was happening? What would cause a transformer to overheat?

I did reconfigure the amp to 230v when I brought it over to Europe from the states. However, I placed the jumper cables correctly, replaced the fuse and attached a new power plug. Did I miss something?

If a K series amplifier transformer does overheat it would shut the amp down as a protection method.
It could be a bad thermal switch which would mean the transformer would need to be replaced. I would however first check the 2-conductor female Molex plug going to sensor/switch. If for some reason it was ever looked at before and the plug wasn't correctly reinserted it could be making a bad connection and causing the same symptoms.