[deserat]

Would the Bottlehead Crack 1.1 OTL work ok with my Sennheiser HD598SE and AKG K612 Pro headphones?

 
That's an interesting question. Interesting enough that I actually found and pulled out my 598's and plugged them into the Crack for the first time since I used them to test that the crack worked. I also pulled the HD600's out just to make sure I wasn't being  partial to the HD800. Even listened with both the 6080 that came stock and 5998 that I've upgraded to.  I can't speak to the AKG's sorry. 

The HD598 with  both the stock and a Tung Sol 5998 sound.... well... not great.  I enjoyed the treble  but the bass distorted and dominated the mids.  Not the kind of distortion that makes you want to rip the headphones off in fear that they might get damaged but that kind of annoying distortion you hear when the band you wanted to see brought a set of speakers that are to big  for the  venue they are playing in. It reminded me of seeing a punk band in tiny bar.  I can't recommend it unless you are underage, really drunk, and looking for a fight.

The AKG's will probably fair better as they are at the bottom end of the Crack's recommended impedance, 120 ohm. Which is roughly double the 598's 50. 

 

[vintinfinity]

I currently have an HD 650 with Magni/Modi 1 and am looking to purchase a used, pre-built BH Crack + non-installed Speedball.

I have zero soldering experience and no tools.

If upon audition I find that the BH Crack works, how likely is it to break several months down the road?

Is there anywhere in NYC where I can bring the BH Crack and ask someone to install the Speedball upgrade for me? Any idea how much this typically takes and how much it would cost?

If it works and everything (impedance and voltage checks) is in order, it is pretty unlikely to suddenly go bad. New ish caps and resistors last quite awhile (many years, decades even). Tubes do get used up but that can take years and years as well.

If you can find an electronic repair specialist or a local hobbyist that is willing to install the speedball, it is pretty simple and doesn't take long. Also easy to remove and put things back the way they were if you don't like it. No idea on cost, but it shouldn't be too bad since it is so simple.

 

[sureshot1234]

That's an interesting question. Interesting enough that I actually found and pulled out my 598's and plugged them into the Crack for the first time since I used them to test that the crack worked. I also pulled the HD600's out just to make sure I wasn't being  partial to the HD800. Even listened with both the 6080 that came stock and 5998 that I've upgraded to.  I can't speak to the AKG's sorry. 

Thank you for that information might just get a hybrid for now get a taste for tube sound to make sure I like it then when I get hd600-700 or beyer770 880 990 250 ohm I will look at the crack again


The HD598 with  both the stock and a Tung Sol 5998 sound.... well... not great.  I enjoyed the treble  but the bass distorted and dominated the mids.  Not the kind of distortion that makes you want to rip the headphones off in fear that they might get damaged but that kind of annoying distortion you hear when the band you wanted to see brought a set of speakers that are to big  for the  venue they are playing in. It reminded me of seeing a punk band in tiny bar.  I can't recommend it unless you are underage, really drunk, and looking for a fight.


The AKG's will probably fair better as they are at the bottom end of the Crack's recommended impedance, 120 ohm. Which is roughly double the 598's 50. 

 

[deserat]

@sureshot1234  was there suppposed to be a reply attached to that quoted post or have I finally become simply quotable?  
 
Edit:
 
Sorry I didn't see the paragraph added in the middle of the quote.  I can fully attest to the quality of the HD600 with the Crack. Best I've ever heard them sound.
 
The 598 are what ruined my life though. I bought them and with the Aune T1. They showed me what music could be like... and well the rest is money flying out the door. The 598 sound pretty good with a hybrid. I've used 'em with a couple and the results were nice.

 

[sureshot1234]

@sureshot1234
  was there suppposed to be a reply attached to that quoted post or have I finally become simply quotable?  

Edit:

Sorry I didn't see the paragraph added in the middle of the quote.  I can fully attest to the quality of the HD600 with the Crack. Best I've ever heard them sound.

The 598 are what ruined my life though. I bought them and with the Aune T1. They showed me what music could be like... and well the rest is money flying out the door. The 598 sound pretty good with a hybrid. I've used 'em with a couple and the results were nice.

Yes it was supposed too lol thank you for the Info I will probably just wait for that amp when I have higher impedance headphones that match well with it

 

[adydula]

598 are 50 ohms
akg 612 are 120 ohms
 
and
 
Crack is an output transformerless amp designed specifically for running higher impedance (200 ohms or higher) headphones like the many Sennheiser, AKG and Beyer designs.
 
So not that good.....
 
Alex

 

[buke9]

Yeah probably not that low, but it does have triple the transconductance of 6080.

My 7802 was cheaper than an 5998. Probably would be good to stock pile a few 7802 since I could see these are going to be very expensive in the future since I could only find one seller with it in stock.

Doc I am wondering if it's possible to drop the impedance even more? I know its possible to lower the impedance by lowering the cathode resistor value, but crack is CCS loaded so I am not sure what to do on the CCS.

Do you mind telling where you sourced the 7802 ? After your post about it I looked high and low and couldn't find one. I just think it might help out my HD 700's just a bit more than the 5998 I have right now. The RCA 6080 sounded bad bloaty bass and everything else for that matter. Screwed up and was looking for a Chatham 5998 and bought a pair of Chatham 6080's (late night eBay and beer) and sounded a lot better but so far the TS-5998 sounds better. The 7802 just might be a little better I hope.

 

[jamesino]

Thanks for the help. I just purchased a used, pre-built BH Crack.
 
Just one question, do I need to plug the Crack directly into my home AC outlet, or can I plug it into a powerstrip shared with other equipment? I live in the USA and have standard US outlets. 

 

[buke9]

Thanks for the help. I just purchased a used, pre-built BH Crack.

Just one question, do I need to plug the Crack directly into my home AC outlet, or can I plug it into a powerstrip shared with other equipment? I live in the USA and have standard US outlets. 

A power strip is fine. Unless you get a lot of noise then something might have a ground loop problem.

 

[jamesino]

It should be safe to leave my HD 650 plugged into the BH Crack when powering on and off the Crack right?
 
All I have to do is turn the volume all the way down, and then power on/off right?

 

[Doc B.]

Yes. The startup voltage with the headphones plugged in is very low. For belt-and-suspenders type assurance you can do the following, if it hasn't already been done -
 
http://bottlehead.com/smf/index.php?topic=2946.0

 

[jamesino]

Are your guys' BH Cracks dead silent 100% of the time when music is not playing?
 
I hear occasional crackles/static in my left ear only. The crackle/static persists even when volume is 0 and/or DAC not plugged into USB port. The loudness of the crackle/static is unaffected by the volume knob. Unplugging the left RCA cable appears to stop the crackle/static. 
 
I tried carefully lifting it up and poking at the wires with a chopstick, but can't reproduce the static.
 
I also tried plugging the BH Crack directly into wall AC outlet, instead of powerstrip, and the crackle/static still persists. I also tried clearing the surrounding area of any electronics, the crackle/static still persists. It occurs from the moment I turn the amp on, and even after it's been playing for 30-45 mins. 
 
It occurs every 5-20 secs for a split second. 
 
Not terribly bothersome, but it'd be great if there was an obvious solution I'm missing. 

 

[buke9]

Are your guys' BH Cracks dead silent 100% of the time when music is not playing?

I hear occasional crackles/static in my left ear only. The crackle/static persists even when volume is 0 and/or DAC not plugged into USB port. The loudness of the crackle/static is unaffected by the volume knob. Unplugging the left RCA cable appears to stop the crackle/static. 

I tried carefully lifting it up and poking at the wires with a chopstick, but can't reproduce the static.

I also tried plugging the BH Crack directly into wall AC outlet, instead of powerstrip, and the crackle/static still persists. I also tried clearing the surrounding area of any electronics, the crackle/static still persists. It occurs from the moment I turn the amp on, and even after it's been playing for 30-45 mins. 

It occurs every 5-20 secs for a split second. 

Not terribly bothersome, but it'd be great if there was an obvious solution I'm missing. 

Not being a expert by any means but if you unplugged the source and it stopped it could be the source that is the problem not the amp. Not a real safe thing to do poking around with the amp on. Easy to budge a wire loose if not connected well and if it was a wooden chopstick wood is not a great conductor but still is one.

 

[Doc B.]

If the noise is occurring at intervals it is possibly due to outside interference from some appliance, cellphone or wifi router. From your description that the noise is there even with the DAC not connected it is apparent that the noise is not coming thru the cables from the DAC. For technical support regarding Bottlehead gear I always recommend posting your inquiry on the Bottlehead forum, as there is a pretty rich experience base.
 
You might try different tubes to eliminate the possibility that one of them is sensitive to interference.

 

[jamesino]

Thanks guys, I'll do some more testing. So to be sure, it is NOT safe to poke around the amp while it is turned on? I got that idea from reading some suggestions on the BH forums where someone recommended doing some poking with a chopstick to see if the crackle can be emulated to help isolate the possible weak solder joint.