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Crack;Bottlehead OTL - Page 96

post #1426 of 4719
Quote:
Originally Posted by uzi View Post

The Lyr is a hybrid amp and definitely has some tubey goodness... but not to the amount that, say, Schiit's Valhalla did when I heard them side by side.  I'd sooner compare the Crack+Speedball to the Valhalla than to the Lyr.  Makes sense... they're both high impedance loving OTL amps.

 

To circle back to your question... the Crack+Speedball would be more like the Lyr than the Soloist.

 

Yep, I'm aware of the design differences.

post #1427 of 4719

So what IS the Speedball upgrade exactly? Is it a linear power supply for the DC portion of the amp?

post #1428 of 4719
Quote:
Originally Posted by ben_r_ View Post

So what IS the Speedball upgrade exactly? Is it a linear power supply for the DC portion of the amp?

 

Erm, no.

 

It is a constant current source (CCS) load for the tubes. Every tube must be 'loaded' with something to allow for current-to-voltage conversion. The default Crack has a resistor load, and replacing it with the Speedball CCS is a very solid improvement.

post #1429 of 4719
Quote:
Originally Posted by Beefy View Post

 

Erm, no.

 

It is a constant current source (CCS) load for the tubes. Every tube must be 'loaded' with something to allow for current-to-voltage conversion. The default Crack has a resistor load, and replacing it with the Speedball CCS is a very solid improvement.


Ah, yea I was way off there. Thanks. Just never done any circuit design with tubes before so Im pretty uninformed on them as a whole. Time to do some fundamental reading.

post #1430 of 4719
Hi, I was planning on buying this kit, however I have no experience with soldering and DIY. Will I be able to build this kit without much problem?
post #1431 of 4719
Quote:
Originally Posted by Dgiant View Post

Hi, I was planning on buying this kit, however I have no experience with soldering and DIY. Will I be able to build this kit without much problem?

Based on my own experience, I think anyone willing could build this kit. The manual is very good.  They key to the build is being patient and double checking your work. I'd recommend you get a variable soldering iron rather than just a fixed wattage. Cooler temps worked well for the Speedball, with it's thin gauge wires, and higher temps were needed for some of the terminals with 2 or more attachments. Don't forget to allocate thought and time for the box and top plate.  Unless you go with a "naked" unfinished build, you'll need to sand, stain/paint etc. In my own case I spent nearly as much time getting the finish on my wood box to my satisfaction as I did on soldering up the kit. 

post #1432 of 4719

Supposedly the best tube for the Crack is a GEC 6AS7G. These normally go for $150-$200. If anyone is interested in buying one with me for substantially less, please PM me. I've got +99 feedback here on Head-Fi.

 

I apologize for posting this here, but I figured I was more likely to find someone interested in joining me here.

 

Best regards,

Adam

post #1433 of 4719
Quote:
Originally Posted by amcananey View Post

Supposedly the best tube for the Crack is a GEC 6AS7G. These normally go for $150-$200. If anyone is interested in buying one with me for substantially less, please PM me. I've got +99 feedback here on Head-Fi.

 

I apologize for posting this here, but I figured I was more likely to find someone interested in joining me here.

 

Best regards,

Adam


How much is "substantially less"? And why is it the best tube?

post #1434 of 4719
Quote:
Originally Posted by Doc B. View Post

We do sell the chassis plate for $45, but we don't sell that particular power transformer (PT-3) due to our agreement with the designer. We have a very similar transformer, the PT-7, that differs only in having a single high voltage secondary winding rather than two windings that are each rated for half as much current in the PT-3. I'm out of town until next week and don't have access to the prices, but I think it is around $80 or $90.


Hey Doc, this quote was from a post you made quite a while ago, but Im curious again about this PT-7 so I had another quick question about it:

 

If the PT-7 lacks the secondary high voltage winding thats the PT-3 has (at half the current) does that mean that when using the PT-7 the high voltage output terminals are already twice the current of one of the two outputs that the PT-3 has but are still at the 150v output that the PT-3 is? In other words in a Crack build the two high voltage output terminals are wired in parallel, to double the current Im assuming, so when using the PT-7 there wouldnt be a need for that and the single output terminals would be used instead giving something near 150V near 70mA?

post #1435 of 4719

Yes, that is correct. Just a note - I don't make it over here as often as our own forum, so my response time (or that of the other technical guys) on technical stuff might be shorter on the Bottlehead Forum.

post #1436 of 4719

Does anyone know how long these usually take to ship?

post #1437 of 4719
Quote:
Originally Posted by Doc B. View Post

There are a couple of threads going at once about this kit in different forums. Forgive me if this seems redundant to anyone following both threads - in the other one I mentioned that yes, this is really intended for high impedance cans, but it will work with low impedance cans though not optimally. I also mention that we have another kit with a low output impedance that works very well with low impedance headphones, so I felt we could afford to do this second, more focused design for the high impedance phone users.

Hi Doc, which amp would then be suitable for the Hifiman HE-500?

post #1438 of 4719
Quote:
Originally Posted by snip3r77 View Post

Hi Doc, which amp would then be suitable for the Hifiman HE-500?

 

You want the S.E.X. for the HiFiMAN HE-500. But if you have any high impedance headphones (Senn HD600, HD650, HD700, HD800, or the 250 or 600 Ohm versions of the Beyer DT770, DT880 or DT990s, or the Beyer T1s), then I highly recommend the Crack. I have owned a fully-balanced, top-of-the-line, no-holds-barred, fully premium Beta 22, a Woo Audio WA22 with $600 worth of tube upgrades, and a WA6 with just about every tube imaginable, and the combination of the Crack with any of my Senn HD600s, HD800s or my Beyer DT990s 600 Ohm smoked all of them. Not even close.

 

I haven't heard the S.E.X., and I'm sure it's very good, but don't just default to the more versatile tool. Sometimes a highly specialized tool can perform better (but in this case only if you have high impedance cans).

 

Best regards,

Adam

post #1439 of 4719
Quote:
Originally Posted by amcananey View Post

 

You want the S.E.X. for the HiFiMAN HE-500. But if you have any high impedance headphones (Senn HD600, HD650, HD700, HD800, or the 250 or 600 Ohm versions of the Beyer DT770, DT880 or DT990s, or the Beyer T1s), then I highly recommend the Crack. I have owned a fully-balanced, top-of-the-line, no-holds-barred, fully premium Beta 22, a Woo Audio WA22 with $600 worth of tube upgrades, and a WA6 with just about every tube imaginable, and the combination of the Crack with any of my Senn HD600s, HD800s or my Beyer DT990s 600 Ohm smoked all of them. Not even close.

 

I haven't heard the S.E.X., and I'm sure it's very good, but don't just default to the more versatile tool. Sometimes a highly specialized tool can perform better (but in this case only if you have high impedance cans).

 

Best regards,

Adam


What about the WA3? Have you compared it to the Crack with the HD-600's?

post #1440 of 4719
Quote:
Originally Posted by ben_r_ View Post


What about the WA3? Have you compared it to the Crack with the HD-600's?

 

Technically speaking, the stock Crack is pretty similar to the WA3. However a Crack with speedball spanks the WA3 in 64 different ways. Add some custom upgrades like a nicer pot, output caps, etc. and you are even further ahead.

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