Bottlehead Forum
Bottlehead Kits => S.E.X. Kit => Topic started by: Gobes on February 27, 2021, 10:28:45 AM
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Folks, not sure what the issue is, but I hear a jarring noise around the drum beats and lost a lot of clarity. Any thoughts about how I could resolve this issue would be much appreciated
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How old is your kit? Is it both channels?
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It's about 3 weeks old.. Yes both channels.. it happens at the bass notes, very small volume increase in volume.
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This could be something as simple as a cold solder joint that is a poor conductor. Maybe you could make a recording of what you're hearing?
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Thank you Paul, I went through the entire amp again, there was q bit of a cold solder at the RCA input. I re soldered, I however still get a jarring sound not as bad as before but just a jarring sound that i would like to address. The tubes are black? May be I replace them? If yes could you advise the tubes you would recommend and from where? Or could it be an issue with the transformers? Thank you and appreciate your help
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Thank you Paul, I went through the entire amp again, there was q bit of a cold solder at the RCA input. I re soldered, I however still get a jarring sound not as bad as before but just a jarring sound that i would like to address.
Can you make a recording? I can't really imagine what a jarring sound would sound like.
The tubes are black? May be I replace them?
Can you post a photo? If you said your tubes were white, I would say to replace them.
Or could it be an issue with the transformers?
This is exceptionally unlikely.
There's an enormous tendency for folks to blame tubes and transformers when their amp isn't working, but most frequently it's solder joints.
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Hi Paul, there are 2 dropbox links
1. T .wav file. The recording was from my cell phone from a SENNHEISER 6xx https://www.dropbox.com/s/nvl9qtm3pi6i21e/ampissue.wav?dl=0
2. The picture of the tubes. https://www.dropbox.com/s/vjdshoz3kf1217z/20210301_204041.jpg?dl=0
Thank you and appreciate your help
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I can hear you clipping the amp in the WAV file, what speakers are you using? The tubes look fine in the second photo, though they don't look like they are pushed in all the way. Your power transformer also appears to be missing. Your plate chokes also aren't properly mounted.
...so what does the inside look like?
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I was using SENNHEISER 6xx headphones. Do you not hear a cracking sound? I can push the tubes in for sure.
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I heard the amp clipping.
I see a lot of build errors without seeing inside the amp.
I'm not sure what more I can offer.
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Sure, I understand and respect that as that (as this is your expertise) I can send you the inside of the Amp. At the end of the day I am tyring to solve the issue and respect that you are trying to help me with it!
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It's also possible that you're overdriving the headphones.
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It's difficult to judge from a recording because we can't hear how loud the headphones are playing, but to me the recording sounds like you are way overdriving your amp and your headphones as you turn the volume up. When you turn it back down in that recording it sounds just fine. Use caution, you can damage the HD6XX with the output swing from a SEX amp. They are only rated for a few tenths of a watt.
The plates of those tubes are indeed supposed to be black, if that is what you mean about the tube being black.
Aside from the fact that the power transformer has been improperly installed it's hard to know if there is anything wrong with the build since we can't see the underside assembly. I would suggest rechecking the voltages and noting if any are off at the same time that you take pics of the underside. If the amp is running not at the proper voltages there could be distortion that is not normal. But it sounds to me like it's probably fine and you have just cranked the volume up farther than the amp or headphones want to go.
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Thank you Doc and Paul. I appreciate your input. As mentioned before you guys are the experts and respect that. The reason I bring this issue up as just a week ago, the clarity was fantastic. Suddenly, something changed. I have taken some additional pictures. As mentioned I love the amp, but it's just different from last week. May be something I might have missed. I have attached futher picks for your references. Thanks again and I respect your time in helping me solve this issue.
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More pics
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Did you recheck the voltages and note any that were off from the numbers in the manual? That will help give us some idea of what is going on.
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Why did you mount the power transformer on the bottom of the amp?
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Thank you Doc and Paul, the voltage were in range as per the manual when checked yesterday to see if there were any cold solders.
With respect to the power transformers, given there were connections from and to the transformer to the other part of the amp my understanding was that it would be at the bottom. I was also initially confused, but I re checked the manual and I was under the impression that it should be at the bottom. Unless you think this is a big mistake?
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Yes, that's a giant mistake.
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"Oh Well"- I guess i either would need to fix that. Do you happen to have any picture i could follow as i am still couple of things. I did check out the manual but still unclear. Thank you again Paul.
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You’d have to remove all the connections going to the power transformer (the one in the middle), then unattach it from the chassis. Then you should follow the instructions for the order of screws, star washers, shoulder washers, and the bell housing in the manual, but the power transformer will sit on your bench on top of the bell housing with the mounting screws already inserted, then you’ll place the amp face down on top of those screws. Make sure you have the terminals oriented the way the manual indicates.
You do have connections to make underneath but there will be plenty of room in the cutout provided.
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FYI - One of those electrolytic capacitors is about to let go, top of it has started to swell out. I would'nt attempt to power the amplifier up again until you have moved the transformer and run through all the resistance checks in the assembly manual as something isnt right.
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"Oh Well"- I guess i either would need to fix that. Do you happen to have any picture i could follow as i am still couple of things. I did check out the manual but still unclear.
The manual is abundantly clear on how this is supposed to be done. We have been using the same set of power transformer mounting instructions for about 15 years and this isn't something that has ever happened.
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Yes Of course. It is "ME" who dint get this right... LOL... Of course it was my first time... Paul, Anyway I can send this to you guys to help me fix this at this point. I am happy to pay the required fee..Totally loved the experience, but definitely, not my strength and of course love the Amplifier and do not want to further mess it up. Truly respect and appreciate your help!
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I think you could get it built properly and I would encourage you to give it another shot!
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Thank you Paul. I appreciate kind your words. I think i must have put in around 65 hours (LOL) which i am sure will take you 6 hours to build this whole thing. I would truly respect the fact if you can help me and let me know how i could ship this out and i will be happy to pay the service fee. Again, just doing this exercise has given me a lot of perspective of what goes in to build an amp and the components involve experience has been absolutely wonderful.
Thank you again!
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Before you pull the trigger on sending it in for repair, I'll mention that a lot of folks seem not to know that the photos in the BH pdf manuals are very high resolution and can be expanded to fit your entire computer screen (e.g., using the magnifying glass symbol in Adobe Acrobat Reader). This gives you a very clear and detailed photo of every installation step. If you simply printed the manual and worked from the printed copy, you might want to explore this.
cheers, Derek
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Thank you Deke609. I appreciate your input.
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let me know how i could ship this out and i will be happy to pay the service fee.
The cost of doing this is very high. It would take me some hours to carefully disassemble what you have, then I would have to start from scratch and build a fresh kit with fresh parts. This would well exceed the cost of a completely new SEX kit.
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Paul, thank you. Let me ask with respect to the the amp built and the instruction (for which I have taken a picture), can you help pin point where exactly the issue is? That would help me a lot. Does the Power Transformer need to be installed from the top of the chasis?
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Yes it installed on top of the chassis plate. re read pages 16,17 and 18 of the manual.
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You can look at the product shot on this page to see how the power transformer should be installed -
https://bottlehead.com/product/single-ended-experimenters-kit-3-0-for-headphones-sensitive-speakers/ (https://bottlehead.com/product/single-ended-experimenters-kit-3-0-for-headphones-sensitive-speakers/)
That photo is also on the first page of your assembly manual.
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Is that power transformer installed on the top or the bottom of the chassis?
The power transformer mounting instructions start on page 16. You need to follow these, not eyeball a photo later in the manual to determine what you're supposed to do. If you followed just the first two steps on mounting the power transformer, it wouldn't have been possible to mount it on the bottom of the chassis.
I see similar mistakes in your build with how you have the plate chokes mounted.
I would suggest rebuilding the amp.
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Hi Paul/Doc
Thank you for your input. I spent the whole day today pretty much rebuilding the whole amp. I also checked every single step from the beginning. Attached are the pictures and the .wav file. The volume was at 50%-60* of the max volume. Please let me know your thoughts.. I still seem to get the jarring/cracking noise. To make sure there was no headphone issue i recorded this on a HiFi Sundara which was different compared to the last time which was on HD6XX
https://www.dropbox.com/sh/ur3qcrx6fjo7eaf/AADyc59tVbtovaCrC8AuEHOma?dl=0
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There is a maximum power that headphones can handle and a maximum output level thereabouts. If you need really loud listening levels, you might want to look into some Grado headphones.
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Paul, thank you. I went back and measured, I am starting to hear the cracking noise starting at 30% of the volume. I'm just reporting what I am hearing and I'm sure you guys are amazing and will be able to help me out. At the end of the day the product is amazing and sometimes things go wrong and thats why I appreciate all your help here..As mentioned yesterday, I went through and did a whole rebuild as well.
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Is that the volume of your dac or volume of the amp?
If it's the volume of your dac what volume is your amp set too?