I bought a Crack off ebay some time ago, pre-built. It came with A?ON output capacitors, an ALPS potentiometer, and one of the tubes appears to not be stock. I've since replaced the RCAs with Neutrik ones and the headphone jack with a Neutrik latching jawn. The octal tube socket just plain sucks and the signal started becoming intermittent, so I took the amp out of commission and I am going to do a whole slew of things to it.
So far I'm impressed with the amp. I didn't think the sound would change that much from the on-board amp on my STX card. Naysayers obviously don't understand that impedance is only measured at one frequency point and high-impedance headphones like my HD-650s are quite demanding of power for bass. You need a healthy reserve of power to drive low frequencies.
When I got it:
After I fiddled with it:
More updates to come later today regarding the teardown of it and what I found.
Edited by ramicio - 8/6/12 at 8:09am
- I ordered new tube sockets. They are the teflon composite type from Parts Connexion. They have a silver-plated crown springs inside the contacts made of beryllium copper.
- The capacitors came dangling. I just used packing tape to keep them held up. It works and can't easily be seen because it's clear. It's not ideal so I designed some brackets in SketchUp and are having them made at shapeways for $3.96 apiece. They made specifically for my capacitors, and you can see the slots for the zip tie. Click this sentence to visit the site and maybe purchase them. I don't get anything for it. I designed them and put them up for everybody.
The headphone jack is crooked and could use some mounting work. I am going to look for a machinist to just nip into the top plate a tiny bit to the shape of the jack's flange so it absolutely will not move. - I am replacing all hardware with torx hardware. I haven't found a place where I can get all the same alloy for all of the sizes I need and inexpensive. McMaster-Carr has them all for cheap, but in different alloys. Aaron's has any size you can imagine and in whatever alloy you want, but small quantities are expensive. I would maybe go for larger quantities if people would go in on a buy (hint hint). Fastenal doesn't really have anything, anymore.
- I am going to have the top plate and transformer end bell powder coated.
- I am looking to build in an audio spectrum analyzer circuit I bought some time ago. I would like it to be after the volume control. Will there be any impedance problems?
- I am looking to add a timed relay circuit that won't connect the headphone jack to the output until a set amount of time after the power is turned on.
- The Speedball upgrade will be done. Does anyone know what hardware (screws) that kit uses? If I have excess quantities from the bulk I order for the Crack itself it would be nice to have these used for mounting the Speedball.
- I am thinking about solid silver wire with cloth insulation, and not with PVC or teflon innards. Does anyone know of a place that sells a decent selection of sizes and colors (red, white, and black)? I found a place in the UK, but I would prefer somewhere in North America. I wouldn't mind getting uncoated wire and just getting the cloth separate.
So far I'm impressed with the amp. I didn't think the sound would change that much from the on-board amp on my STX card. Naysayers obviously don't understand that impedance is only measured at one frequency point and high-impedance headphones like my HD-650s are quite demanding of power for bass. You need a healthy reserve of power to drive low frequencies.
When I got it:
After I fiddled with it:
More updates to come later today regarding the teardown of it and what I found.
Edited by ramicio - 8/6/12 at 8:09am
Server & video encoder
(12 items) |
Quiet Desktop
(15 items) |
| CPU | Motherboard | RAM | Hard Drive |
|---|---|---|---|
| i5-2500k | ASUS P8Z68-M Pro | 16 GB (4 x 4GB) Mushkin Enhanced Silverline DDR... | 64GB Kingston SSD |
| Optical Drive | Cooling | OS | Monitor |
| Blu-ray reader and DVD/CD burner combo drive | Scythe Big Shuriken 2 Rev. B | Windows 7 Ultimate x64 | 1440x900 old LG LCD with anti-glare film peeled... |
| Keyboard | Power | Case | Mouse |
| Dusty old Dell PS/2 | Seasonic 560 watt modular | Lian-li PC-V354B | Some generic one from Best Buy |
| Mouse Pad | Audio | Audio | |
| Plain black | ASUS Xonar Essence STX | Bottlehead Crack w/ Speedball | |
| View all | |||
|
Server & video encoder
(12 items) |
Quiet Desktop
(15 items) |
| CPU | Motherboard | RAM | Hard Drive |
|---|---|---|---|
| i5-2500k | ASUS P8Z68-M Pro | 16 GB (4 x 4GB) Mushkin Enhanced Silverline DDR... | 64GB Kingston SSD |
| Optical Drive | Cooling | OS | Monitor |
| Blu-ray reader and DVD/CD burner combo drive | Scythe Big Shuriken 2 Rev. B | Windows 7 Ultimate x64 | 1440x900 old LG LCD with anti-glare film peeled... |
| Keyboard | Power | Case | Mouse |
| Dusty old Dell PS/2 | Seasonic 560 watt modular | Lian-li PC-V354B | Some generic one from Best Buy |
| Mouse Pad | Audio | Audio | |
| Plain black | ASUS Xonar Essence STX | Bottlehead Crack w/ Speedball | |
| View all | |||
