Bottlehead Crack - Illustrated write-up

L

lokesen

New member
I made this little write-up illustrating the process of making the Bottlehead Crack and modding it.

There are 5 parts and I do hope you'll find some inspiration here, if you haven't made a Bottlehead Crack yet.

Cabinet and Chassis http://diy.koenigs.dk/2014/02/20/6/
Mounting the Parts http://diy.koenigs.dk/2014/02/20/mounting-the-parts/
Soldering the components http://diy.koenigs.dk/2014/02/21/soldering-the-components/
Speedball Upgrade - http://diy.koenigs.dk/2014/02/25/speedball-upgrade/
Capacitor Hot-Rod'ing - http://diy.koenigs.dk/2014/02/26/hot-rodding-with-film-caps/
Stepped Attenuator & legendary G.E.C CV 2523 tube http://diy.koenigs.dk/2014/03/18/stepped-attenuator-legendary-g-e-c-cv-2523-tube/

To make room for the next project, this beauty is now up for auction: http://www.ebay.co.uk/itm/141272593815?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

Ends the May 5
 
Very nice, good job on the website too.

I see you also built an O2, i can pretty much guarantee it will only be used as a paperweight from now on :)

 
Hi lokesen and all.
Nice job.
Lots of pictures, good, simple and clear explanations.
Very well written and much more.
I am still unsure if all the up-grades make such a big improvement on sound.
The stock Crack is already very good,
how much better can it get with the same headphones? (HD-650)
I only spend my $$$ when I can hear a huge difference/improvement,
up to now, that did not happen often with my audio stuff.
Thanks for that fantastic write-up.

Guy 13
 
Guy 13 said:
Hi lokesen and all.
Nice job.
Lots of pictures, good, simple and clear explanations.
Very well written and much more.
I am still unsure if all the up-grades make such a big improvement on sound.
The stock Crack is already very good,
how much better can it get with the same headphones? (HD-650)
I only spend my $$$ when I can hear a huge difference/improvement,
up to now, that did not happen often with my audio stuff.
Thanks for that fantastic write-up.

Guy 13
Click to expand...
Thanks, I totally agree. Changing caps is not good value for money. Upgrading your headphones to HD800 would probably make more sense. But differences will always be subtle because HD650 and Bottlehead Crack is already high-end.
 
Interesting I was really surprised at the difference doing similar made the change after switching pots was far from subtle with the 650. With the 650 the differences was more subtle. While with my Beyer T1's the changes are much more noticeable.
I concluded rightly or wrongly that the 650's must be very close to their peak performance wise.  I also found my capacitors required about 100hrs plus to settle in and start sounding their best. With that in mind you should still have some improvements to come.   
 
Here is my concern with the "non upgrade "thought process.  IMO, you need to maximize the quality of the amp to fully take advantage of the  upgraded headphones.  Think of it in order of $$$$ magnitude.  Just using MSRP, Senn HD650's are $500, the HD800's $1500.  The headphone upgrade costs $1000 or three times the cost of the HD650's.  I am befuddled by the idea that it is a better sound value investment than upgrading the amp!!  The law of diminishing returns is unavoidable. 

So are the 800 better than the 650's? Yes, but by what level of improvement and where in the reproduction spectrum is that improvement achieved?  For the sake of argument, let's say that the 800's are 25% better for the 1000 bucks more. (the %age improvement is probably a bit high given audio's diminishing returns slope!) Just for grins & giggles, let's say each 1% improvement costs $40!! ($1000/25%)

Does the stock built Crack capture 100%of the HD650 capability?  Probably not.  So logically  the stock Crack would capture an even lower percentage of the 800's improvement.  The basic tenet of "match the amp to the speakers/headphones" is still valid!  ( Just a thought!  If I were looking to get the 800's, I would probably be looking at the Mainline first.  Likely a better match!!)

Every commercial product is built to a price point.  This includes kits.  The reason for DIY kits, to me, is simple....buy a well engineered design, (anything from Doc, PJ, etal at BH), and then address the "price point" selection with better quality.  For example, the stock Crack's major commercial compromise, IMO, is the electrolytic output caps.  The caps are very good electrolytics, but they are 'lytics.  I am assuming that the caps were chosen based on cost, size and ease of construction for the builder.  But even very good "for audio" electrolytic caps are not that great sounding as compared to film caps.

The design of the Crack will let you hear every improvement, but logically the first upgrade step must be the output caps! Why?  Every other upgrade to the signal path must go through the output caps to get to the headphones.  So what is the cost of improving the output caps? It can be fairly low by bypassing the 'lytics with quality film caps or outrageous with high capacitance boutique caps.

So what would I do before dropping $40 for each 1% improvement? 
1) Change out, (or bypass), the output caps for the best quality/size fit caps that I can accommodate.

2) Change out the stock volume pot for a high quality TDK, Noble,  Alps or stepped attenuator, (remember the source signal goes through here before any amplification!)

3) Improve the power supply with a choke and a film/PIO final PS cap. Clean power = clean signal!

Now once I have done all of this I can compare the 650's to the 800's, (insert your favorite $$$ blackholes here!)  Short read...Spend a $100  for a far greater improvement, before you spend an additional $1000 for a potentially lesser overall improvement.  You may find that giving your current phones the benefit of the  best that the Crack offers is all you need!

Of course YMMV!

Cheers,
Geary
 
Geary, that is a very good post and I think you are spot with the $100 figure also. When taken into context with say a aftermarket cable upgrade for the HD650's it really is a no brainer.

I have a Valab stepper fitted to my Crack and a new Blue velvet pot in my parts box, I think I will fit it over the weekend. the valab was a very noticeable mod (I was over the moon with the difference) I think it was about $10 more than the blue alps velvet just under $30. So it would be a worth while experiment to see how they compare.

 
JamieMcC said:
Interesting I was really surprised at the difference doing similar made the change after switching pots was far from subtle with the 650. With the 650 the differences was more subtle. While with my Beyer T1's the changes are much more noticeable.
I concluded rightly or wrongly that the 650's must be very close to their peak performance wise.  I also found my capacitors required about 100hrs plus to settle in and start sounding their best. With that in mind you should still have some improvements to come. 
Click to expand...

I think you're right about the capacitors, I can hear a tiny bit of sibilance in the treble and it sounds like they need to burn in more. But I have fun burning them in, so it's all good :) 
 
galyons said:
Here is my concern with the "non upgrade "thought process.  IMO, you need to maximize the quality of the amp to fully take advantage of the  upgraded headphones.  Think of it in order of $$$$ magnitude.  Just using MSRP, Senn HD650's are $500, the HD800's $1500.  The headphone upgrade costs $1000 or three times the cost of the HD650's.  I am befuddled by the idea that it is a better sound value investment than upgrading the amp!!  The law of diminishing returns is unavoidable. 

So are the 800 better than the 650's? Yes, but by what level of improvement and where in the reproduction spectrum is that improvement achieved?  For the sake of argument, let's say that the 800's are 25% better for the 1000 bucks more. (the %age improvement is probably a bit high given audio's diminishing returns slope!) Just for grins & giggles, let's say each 1% improvement costs $40!! ($1000/25%)

Does the stock built Crack capture 100%of the HD650 capability?  Probably not.  So logically  the stock Crack would capture an even lower percentage of the 800's improvement.  The basic tenet of "match the amp to the speakers/headphones" is still valid!  ( Just a thought!  If I were looking to get the 800's, I would probably be looking at the Mainline first.  Likely a better match!!)

Every commercial product is built to a price point.  This includes kits.  The reason for DIY kits, to me, is simple....buy a well engineered design, (anything from Doc, PJ, etal at BH), and the address the "price point" selection with better quality.  For example, the stock Crack's major commercial compromise, IMO, is the electrolytic output caps.  The caps are very good electrolytics, but they are 'lytics.  I am assuming that the caps were chosen based on cost, size and ease of construction for the builder.  But even very good "for audio" electrolytic caps are not that great sounding as compared to film caps.

The design of the Crack will let you hear every improvement, but logically the first upgrade step must be the output caps! Why?  Every other upgrade to the signal path must go through the output caps to get to the headphones.  So what is the cost of improving the output caps? It can be fairly low by bypassing the 'lytics with quality film caps or outrageous with high capacitance boutique caps.

So what would I do before dropping $40 for each 1% improvement? 
1) Change out, (or bypass), the output caps for the best quality/size fit caps that I can accommodate.

2) Change out the stock volume pot for a high quality TDK, Noble,  Alps or stepped attenuator, (remember the source signal goes through here before any amplification!)

3) Improve the power supply with a choke and a film/PIO final PS cap. Clean power = clean signal!

Now once I have done all of this I can compare the 650's to the 800's, (insert you favorite $$$ blackholes here!)  Short read...Spend a $100  for a far greater improvement, before you spend an additional $1000 for a potentially lesser overall improvement.  You may find that giving your current phones the benefit of the the best the Crack offers is all you need!

Of course YMMV!

Cheers,
Geary
Click to expand...

+ it's so much fun modding your equipment yourself, compared to buying new stuff. That's worth a lot to me.
 
Hi galyons.
Thanks for sharing with us your experience.
Everything you wrote make sense.
I think Bottlehead should offer (As an option) up-grade kits to the DIYers.
Some DIYers don't want to chase around parts and/or don't have to experience to choose
the right up-grade parts that really makes a difference.
Is Doc reading this?
Doc, you could make extra $$$ on this.

Guy 13

 
Retailing parts is a different business than manufacturing and supporting kits, and we have found that it is better for us to focus on our core proficiency. The parts that are included in the kit have been chosen based upon 20 years of experience doing this stuff. Any talk about "designing to a price point" is going down a slippery slope. 

We went thru this deal with attenuators when we developed the BeePre. We started with the stock pots, tried Alps Blue, PECs, S&B TVCs, Goldpoints, and probably a few other very highly regarded attenuators I don't recall. They were somewhat better than the stock pot, but when it came down to it we had to design our own attenuator to get something significantly better sounding than stock. Hence we sell the Bee Quiet kit. If you want to hear a Crack sound significantly better put a Submissive in front of it wth very short interconnects and replace the stock pot with 100K grid loading resistors.

Along these lines I spend a fair amount of time trying to explain to people that a stock Mainline is going to sound better than throwing $1500 worth of parts at a Crack, not because it has more expensive parts - which it does- but primarily because the circuit just plain sounds better.

 
Doc B. said:
Any talk about "designing to a price point" is going down a slippery slope. 

Along these lines I spend a fair amount of time trying to explain to people that a stock Mainline is going to sound better than throwing $1500 worth of parts at a Crack, not because it has more expensive parts - which it does- but primarily because the circuit just plain sounds better.
Click to expand...

Doc,
This was the exact context of "designing to a price point".  Slippery slope or not,  the Crack is not the Mainline!! It wasn't designed to be.  If the Mainline could be produced to retail at the price point of the Crack, there would be no commercial need for the Crack.

Cheers,
Geary
 
lokesen said:
    .  .  .    Changing caps is not good value for money.  .  .  . 
Click to expand...

If you are going to pay over $100 for capacitors I agree.  But there are more moderate priced caps out there.  For the output caps you are replacing electrolytics.  They are polarized and are intended for a power supply not the audio path. 

At 100uF I fully understand why Bottlehead doesn't use a film here.
 
I do think an attenuator upgrade kit is a good idea, i had suggested that before. But thats about it, for anything else you really need to DIY.

For example i found upgrading the Solen output cap on my S.E.X. made a very nice difference, the Solen is a $3 part, vs the Mundorf which is a $72 part. Its not 24 times better, nor can anybody reasonably expect Doc to stock them in case anybody should decide they want them.  The Solen cap is however fantastic for the price, and i think that's the key here with the parts Bottlehead uses, the perfect balance of cost vs performance.

Or to put it another way, if they were to start using $70 capacitors and $200 attenuators it would be a long way from a $500 kit.
 
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