The Crack seems a bit pricey to me at $430 for the kit considering it comes with cheap parts and the price of the Chinese amps - which commercial alternative is there, assembled, or alas, a kit ?
1st pic is supposedly the Crack (OTL)
2nd is one of the few generic amps I could find on Aliexpress which has a transformer and comes with a schematic
3rd looks similar and uses the same tubes but I don't see the transformer
1st pic is supposedly the Crack (OTL)
2nd is one of the few generic amps I could find on Aliexpress which has a transformer and comes with a schematic
3rd looks similar and uses the same tubes but I don't see the transformer
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I can't comment on the quality of the various kits.
But you have to factor what else is included in the price.
When you buy the bottlehead kit you know exactly what you will get. A known product, known schematics, known parts and the backup support of the bottlehead forum etc if you have issues.
If you buy the Ali Express kit, you get unknown parts, probably schematic only with no build instructions and most likely little or no after sales service/support if you have issues.
You might get lucky and end up with a quality product at a discounted price. But you might also get counterfeit parts, parts that don't match the schematic, circuit board issues etc.
The Ali Express kit is a calculated risk. If you are a confident builder and you think you can deal with whatever comes it could be a great buy.
If you are less confident then the certainty and support of the Bottlehead is probably worth the extra money to make sure you get a quality result.
As an example. My first tube preamp was a fairly expensive kit from the USA. I got great results due to the parts quality and after sales support provided.
I could build the same thing now for 1/3 of the price I paid but I would not have gotten the same results without paying the premium first time round.
But you have to factor what else is included in the price.
When you buy the bottlehead kit you know exactly what you will get. A known product, known schematics, known parts and the backup support of the bottlehead forum etc if you have issues.
If you buy the Ali Express kit, you get unknown parts, probably schematic only with no build instructions and most likely little or no after sales service/support if you have issues.
You might get lucky and end up with a quality product at a discounted price. But you might also get counterfeit parts, parts that don't match the schematic, circuit board issues etc.
The Ali Express kit is a calculated risk. If you are a confident builder and you think you can deal with whatever comes it could be a great buy.
If you are less confident then the certainty and support of the Bottlehead is probably worth the extra money to make sure you get a quality result.
As an example. My first tube preamp was a fairly expensive kit from the USA. I got great results due to the parts quality and after sales support provided.
I could build the same thing now for 1/3 of the price I paid but I would not have gotten the same results without paying the premium first time round.
No way the 1st pic is the Crack. Wrong tubes to start with. The Crack is extremely similar to the Van Waarde of headwize: A Single-Ended OTL Amplifier for Dynamic Headphones. – HeadWize Memorial
The 2nd has a different input stage but is rather similar for the output. The 3rd has a more similar input stage (with too much gain though with the cathode bypass cap, absent on the crack) but the biasing of the output is different (in my view it makes more sense actually). Still it should be the closest.
Edit: and all the above by Sadface is true.
The 2nd has a different input stage but is rather similar for the output. The 3rd has a more similar input stage (with too much gain though with the cathode bypass cap, absent on the crack) but the biasing of the output is different (in my view it makes more sense actually). Still it should be the closest.
Edit: and all the above by Sadface is true.
These are valid reasons but there are already built amps which cost 1/3 the price on aliexpress and it's just hard to argue with that considering my first preference isn't to build it myself.
Did you solve the circuit from a glance? wow.
Does any include the Camille Cascode Constant Current Source (Speedball)?
The only amp on aliexpress which has OTL in its name is the DarkVoice, but it comes with no schematic and no circuit pic...
Having built half a dozen Cracks, and had a Darkvoice across my workbench i can assure you there is no comparison between them.
The Darkvoice sufferered from a lot of hum from the heater circuit, ended up converting the 6SN7 heater to DC to fix it. The operating point of the tubes is questionable, they run far too hot, as is the rest of the circuit design. The HV power supply for example has a ludacris amount of capacitance, something like 3300uf at 250v which is completely unnecessary. Dont waste your money unless you are prepared to fix its problems.
The Darkvoice sufferered from a lot of hum from the heater circuit, ended up converting the 6SN7 heater to DC to fix it. The operating point of the tubes is questionable, they run far too hot, as is the rest of the circuit design. The HV power supply for example has a ludacris amount of capacitance, something like 3300uf at 250v which is completely unnecessary. Dont waste your money unless you are prepared to fix its problems.
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What nobody mentioned yet: do you accept the risk of a shoddy transformer burning your house down or electrocuting you if the isolation fails?
Most power transformers alone cost more than what these ebay/alie amps cost in total. So you'll likely get a core being pushed to the limit (making it run hot), with isolation material made from recycled toilet paper, on an amp that has no added isolation between the circuit and the thing you conveniently put straight over your ears.
Most power transformers alone cost more than what these ebay/alie amps cost in total. So you'll likely get a core being pushed to the limit (making it run hot), with isolation material made from recycled toilet paper, on an amp that has no added isolation between the circuit and the thing you conveniently put straight over your ears.
I built a Crack+Speedball and I received in the kit a bad tube (later their support sent me a new one after debugging it over email) which is one reason why I'm reluctant to go the kit way again.
What's the Crack secret? It doesn't measure very well as in the link above. Is it the PSU? I've had many pitch dark background amps but the Crack was darker... idk what made it different.
That's all valid but remember there's a lot to be saved from producing and selling en masse alone so as a general rule the Chinese generic amps should still cut costs by a large margin selling the same. A lot of the consumer electronics you see on Amazon is identical only rebranded.
This thread made me realize it's for sure easier to buy SS for the sole reason it's easier to know what you'll get.
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So, to summarize: you have little interest in building the amp yourself, and are asking the forum to help you identify a cheap Chinese knock-off of the Bottlehead Crack with Speedball?
I wanna get the sound again but I find it hard to justify building a kit considering how mass production can reduce costs.
If you want something plug and play, grab one of the ready made ones.
But at the very least check the safety ground (multimeter probe on the prong and check every metal part of the chassis you can touch) and plug it into a socket which is behind a GFCI. That'll save your behind 99/100 times if excrement hits the fan.
keep in mind that I see complaints about hum issues so you may have to change the heating of the smaller tube to DC to get it silenced. And someone already suggested that the cathode resistor may have to be increased a little as that output tube is running hot.
And don't plug in your <32 ohm headphones, this is meant for high impedance headphones.
But at the very least check the safety ground (multimeter probe on the prong and check every metal part of the chassis you can touch) and plug it into a socket which is behind a GFCI. That'll save your behind 99/100 times if excrement hits the fan.
keep in mind that I see complaints about hum issues so you may have to change the heating of the smaller tube to DC to get it silenced. And someone already suggested that the cathode resistor may have to be increased a little as that output tube is running hot.
And don't plug in your <32 ohm headphones, this is meant for high impedance headphones.
You get what you pay for. The words cheap and tube amp are rarely in the same sentence. The cheap designs from China are more of a starting point than a finished product. They will need some modifications to be good. So it comes down to what your time is worth.
It doesn’t answer the question of why such an expensive kit would come with a bad tube to begin with. Pay top dollar and get mediocrity?
It could be something as simple as shipping damage maybe? Or it could be a noisy tube and the noise didn't show up on a tube tester... There are many possibilities.
There are many possibilities but for me the more I spend the less tolerance I have. If the kit was cheap the extra time and effort I have to spend troubleshooting QC issues is expected. For an expensive kit that I have paid top dollar NOT to have to deal with such issues my tolerance is almost zero.