Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: xcoolhandx on February 28, 2014, 11:09:47 AM
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I bought this unit with the speedball upgrade already pre-build
I don't know what to make out of it ...I recently noticed resonance coming through my right channel (there is some in the left but not as much),for example when the unit is ON and I have nothing playing any tapping on the base or aluminium plate-most pressent when tapping next to headphone jack will travel through right channel ,it's more of a micro phonic sound ...what gives ???
I've tried changing tubes ,headphones and it's not going away ,I was about to swap some caps but this have to be addressed first ,any help ?
I tried power tube on my Darkvoice336SE and it's silent ,tried 3 different tubes with the same results
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So don't tap on it.
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Microphonics are a tube related problem. The longest thread in the Crack Folder is Tube Rolling.
I suggest you read some of the thread and purchase a pair of new tubes and see how it goes.
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Microphonics are a tube related problem.
Microphony is not a problem, it's an attribute.
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@ fullheadofnothing,I'm just given the example ,what lead me to it was "pulling to one side" ->left channel always seems to be stronger
@Grainger49, I'm not sure if I used the right description as "microphonic" or resonance but anyway you want to call it -it shouldn't be there -I'm not tapping on the tube for crying out loud ,I have plenty of new tubes so pointing me to a tube rolling thread won't solve the problem
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Does it make any difference where on the base you tap? Of necessity the tube sockets are bolted to the chassis so it should come as no surprise that there is noise. If this was a power amp connected to a speaker then the sound the speaker makes could cause resonance, the only way that could happen in a headphone amp is if one of the tubes was wearing the phones ;D Seriously if the loudness varies by where you tap, then possibly something needs tightened. And we also need to understand what this "resonance" is to be able to help you. Good luck
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Microphonics are a tube related problem.
Microphony is not a problem, it's an attribute.
So you are saying that all 12AU7s and all 6080s are microphonic?
This is not a problem I have had with the 12AU7s in my FP 2.
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Does it make any difference where on the base you tap? Of necessity the tube sockets are bolted to the chassis so it should come as no surprise that there is noise. If this was a power amp connected to a speaker then the sound the speaker makes could cause resonance, the only way that could happen in a headphone amp is if one of the tubes was wearing the phones ;D Seriously if the loudness varies by where you tap, then possibly something needs tightened. And we also need to understand what this "resonance" is to be able to help you. Good luck
worthless post ..why bother posting bro?
P.S. I can tap anywhere on DV336SE -tube included and you won't here a thing .."good luck" to you
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Well that looks like a very clean build it takes a little bit extra time and trouble to do so.
I can only suggest twisting your rca input cables together and see if that helps. I had some microphonics when I touched the volume knob I would get a hum take my finger off and it went, twisting the rca input cables cured this. Its a easy enough thing to try you never know.
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thanks Jamie ,finally someone that actually trying to help ,yeah Crack seems to be very vulnerable to anything and everything ,just noticed very similar thread here with dead end as well
http://bottlehead.com/smf/index.php/topic,5806.0.html
right channel is barely audible
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If that were mine I'd run through the ohm and voltage tests. Then while it was upside and playing I'd do the old chopstick test and push around on things gently with particular attention to the rca connectors, volume pot, and tube sockets. Problem might reveal itself.
Also don't discount craziness like input cables and sources.
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If that were mine I'd run through the ohm and voltage tests. Then while it was upside and playing I'd do the old chopstick test and push around on things gently with particular attention to the rca connectors, volume pot, and tube sockets. Problem might reveal itself.
Also don't discount craziness like input cables and sources.
I have Fluke MM and will do what you suggested ,I want to get to the bottom of this
Thanks
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I have had a few noise issues with my Crack in the past and all of them have been due to outside influences such as routing of connecting cables, power supply extension leads, even a electric radiator in a different part of the house that was tripping in and out on a thermostat causing a intermittent hum on the Crack (that one was a real puzzle) and was very frustrating at the time. I am sure the resident gurus here will be able to offer some better ideas than myself to help chase down the cause.
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FWIW mine is dead silent. You buy this already assembled by someone else and you seem to think that this is a problem related to design rather than the obvious solution. Maybe you should be talking to the "bro" that sold it to you, rather than coming here and dissing an extremely successful design. Have a nice life
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thanks Jamie ,finally someone that actually trying to help . . . .
I think my post was an attempt to help....
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So you are saying that all 12AU7s and all 6080s are microphonic?
This is not a problem I have had with the 12SU7s in my FP 2.
Yes, all tubes will be microphonic to some extent.
If your Foreplay 2 was a headphone amp, you might notice this. (I can tap on 12AU7's in a Foreplay when it's driving a Crack and hear this quite clearly)
To the OP - you swapped 6080's between the Crack and your other amp, but likely you have a 12AU7 that is more microphonic than normal. You can replace it with a different tube, or just recognize that this is normal with a certain percentage of tubes and keep using it.
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Everyone, chill.
If you are certain that it isn't a tube, then the next step is to turn the amp over in its base, carefully plug it in, turn it on and take a non conductive implement like a chopstick or plastic pen and tap the components near the area where you noticed the sound coming when you tapped the top. Listen over your headphones for the ringing, you may find a part that is loose and vibrating when you tap it, that is transmitted into your headphone cable or into a tube.
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FWIW mine is dead silent. You buy this already assembled by someone else and you seem to think that this is a problem related to design rather than the obvious solution. Maybe you should be talking to the "bro" that sold it to you, rather than coming here and dissing an extremely successful design. Have a nice life
you are the one that's full of assumptions and then some ,I bought this from someone that had this already assembled and came here to find solution to a problem I'm having since that's what this forum is for, so please go and do something that have a meaning in life instead of hanging around here and acting all bad,trust me I wouldn't have a problem putting this together but my eyesight is not all that great anymore
Thank you for your helpful input Sir
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Let's get back to the troubleshooting issue. Please try what I suggested below and let us know if it helps to narrow down the cause.
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I sincerely hope you are able to fix your problem,and am sorry that you are having problems with your eyesight. However you do catch more flies with honey than vinegar and dismissing very experienced people's advice out of hand is not a good way to start off around here
Peace, love, and happiness
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The guy that built that thing is suspect.
I see an LED propped way up from the board right next to one that is flush. I see lots of unclipped leads. I see a lack of solder. I see a resistor connection that was clipped too short. I see transistors that are too low.
Yup, I suspect the age old assembly problems.
I can tell you that mine does not ring even if I tap the tubes let alone the plate or the base.
Good luck!
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Everyone, chill.
If you are certain that it isn't a tube, then the next step is to turn the amp over in its base, carefully plug it in, turn it on and take a non conductive implement like a chopstick or plastic pen and tap the components near the area where you noticed the sound coming when you tapped the top. Listen over your headphones for the ringing, you may find a part that is loose and vibrating when you tap it, that is transmitted into your headphone cable or into a tube.
I did what you suggested with no avail ,can't find the source , still pulling to the left (hear more in the left channel)
EDIT; if you want I can take close-up pics of all the soldering ,I also noticed that one of the square PCBs (I think it's called LED and that's what the MikeB was referring ) is tilted-there is little to much solder on one of the heatsink posts ,don't know if it's this would be the problem
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I was going through the manual today just looking for my culprit ,here is the first thing that didn't look right quote from manual ;
"Attach the 1/4” stripped end to terminal
13U. Thread the 1” stripped end
through terminal B5, then through
terminal B2. Solder 13L, solder B5"
comparison manual and my crack
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I will again say that this is most likely a microphonic 12AU7, have you tried a substitute?
In my opinion, the amp looks well built.
In my experience, I haven't had microphonics in tube equipment come from anything but the tubes themselves.
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I will again say that this is most likely a microphonic 12AU7, have you tried a substitute?
In my opinion, the amp looks well built.
In my experience, I haven't had microphonics in tube equipment come from anything but the tubes themselves.
I understand what you saying and wouldn't bother posting here ,I'm well aware of all the ins and outs of the valve tube in general ,..let me repeat my self again ..there is imbalance-> I can here more in the left channel then I can here in the right one (no matter what tube I use-TS 7236,5998,GEC 6AS7G,Haltron 6AS7G A1834 and for driver -new JJ ECC82,NOS 1952 Lansdale 12AU7 Black Plate,GE 12AU7 and two other tubes) that was the main reason for me to investigate what was causing it ,the tapping was just a tale tale of the right channel being noisy-lack off proper balance between both channels and an example of something not being right that's why I mention it ,left channel is dead silent
I'm waiting for some 20 gauge wire and will disassemble this thing myself ..half blind ,will give some more slack for some wires especially around 9 pin socket and trim
excess leads
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Is the channel imbalance present regardless of volume control position?
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no it's not ( I did read the FAQ ) ,sorry I edited my last post
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OK, if you have an imbalance at low volumes, you can pad the input of the Crack, or decrease the amount of signal coming out of your source.
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NO I don't have imbalance at low volume just like I mention it in my last post
as for imbalance it's not a big difference but you can tell
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there is at list two or three threads in the last two pages mentioning bad right channel ..co-incidents ?
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The next thing to do would be to take voltage measurements.
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thanks Jamie ,finally someone that actually trying to help ,yeah Crack seems to be very vulnerable to anything and everything ,just noticed very similar thread here with dead end as well
http://bottlehead.com/smf/index.php/topic,5806.0.html
right channel is barely audible
I'm not sure how this has a dead end? There was an issue present in this thread that would show up on voltage checks (and probably resistance checks), and once the error was remedied, the amplifier performed to its specifications.
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The next thing to do would be to take voltage measurements.
I have to look in manual since I'm not sure where you take the measurements,also
It took some time, but I found what was causing the buzzing noise in the right channel. I had previously swapped speedball boards left to right, but this had no effect. Eventually I noticed that the red wire coming from the pot was running right beside the heater wires toward the input tube. I rerouted the red (signal) wire to approach the socket terminal from another direction and this completely fixed the problem.
here is my 9 pin socket
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Did you change the output coupling capacitors?
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yes I did but nothing changed
,here is the weird part ..when I have the unit on it's side everything is nice and even and no noise
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A change by laying the unit on its side would tend to indicate that gravity is changing the contact of something. The first thing that comes to mind is that the headphone plug might be making better contact inside the jack. That might be supported by your earlier mention of some kind of microphony when tapping near the jack. Perhaps the plug was overheated a bit and distorted a little when soldered.
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I already ordered new phone and RCA jacks from this place
https://www.parts-express.com/ShoppingCart.aspx
and Blue velvet arrived today as well
EDIT; were there any socket complains in the past and what would be good socket replacement ?..just in case
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EDIT; were there any socket complains in the past and what would be good socket replacement ?..just in case
Yes, we have had at least one customer remove a teflon upgrade socket because it was defective.
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little update on this issue..
impedance no more rerouted few wires ,swapped phone jack ,RCA jack and I'm back in the game (the tapping noise is almost gone )
P.S. I recently noticed this thread (probable cause of my dead HE400s ..I think I connected my cans to early -loud pop=only one channel active)
http://bottlehead.com/smf/index.php/topic,2946.0.html