AlanHell
500+ Head-Fier
point taken
Thanks for response anyway~~~ Seems that not many people want to do budget tube, not now it is dominated by SS amps.
I would love to have some woo audios but they are just way too expensive~~
point taken
Thanks for response anyway~~~ Seems that not many people want to do budget tube, not now it is dominated by SS amps.
Project Ember from garage1217,it's an excellent headphone hybrid amp, very powerful and versatile (can drive the majority of cans, from grado to AKG K1000, from Sennheiser HD800 to Hifiman HE6), you can tune your sound with different settings (output impedance, gain, use of the input capacitors), and change tube without any settings, and it's compatible with a huge amount of tubes (ECC81/12AT7, ECC82/12AU7, ECC83/12AX7, ECC88/6DJ8, ECC86, ECC85, ECC189, E180CC, E80CC, 6BZ7, 6GU7, 12BH7A, 6N1P, 6N2P, 6N23P, 6N27P, etc...), a great amp : http://www.garage1217.com/graphic_design_004.htm
for pricing : http://www.garage1217.com/graphic_design_006.htm
There are numerous budget tube amps but most are NOT designed for low impedance headphones.
OTL (output transformerless amps) are simple and can be inexpensive, depending on the components used and chassis etc. e.g. Bottlehead Crack.
This design is great for high impedance cans (HD600/650 etc) does not generate enough current to drive low impedance headphones. To generate the required current a tube amp needs output transformers e.g. WA-6. Good transformers are hand wound and add cost and complication. If you look at Woo WA-3 vs WA-6 the transformers add $140. Woo and Bottlehead both provide info on matching their amps to different headphones.
http://wooaudio.com/docs/wooaudio_amplifier_comparisons.pdf
http://www.bottlehead.com/et/whichheadphoneamp.htm
The inexpensive option is a "tube hybrid" e.g. Little Dot 1+ or Project Ember (referred above). These amps combine op-amps (usually) driven by driver tubes to give tube sound with SS output.
The hybrid tube technology has been around and is well tested, even in higher end gear such as the Peachtree or PAthos amps. If you like to try one that is better shielded get the Little Dot 1+ for $120 or Antique Sound LAbs makes on that's $350 but has a separate power supply ASL HB-1:
There are numerous budget tube amps but most are NOT designed for low impedance headphones.
OTL (output transformerless amps) are simple and can be inexpensive, depending on the components used and chassis etc. e.g. Bottlehead Crack.
This design is great for high impedance cans (HD600/650 etc) does not generate enough current to drive low impedance headphones. To generate the required current a tube amp needs output transformers e.g. WA-6. Good transformers are hand wound and add cost and complication. If you look at Woo WA-3 vs WA-6 the transformers add $140. Woo and Bottlehead both provide info on matching their amps to different headphones.
http://wooaudio.com/docs/wooaudio_amplifier_comparisons.pdf
http://www.bottlehead.com/et/whichheadphoneamp.htm
The inexpensive option is a "tube hybrid" e.g. Little Dot 1+ or Project Ember (referred above). These amps combine op-amps (usually) driven by driver tubes to give tube sound with SS output.
The hybrid is quiet new and not sure how mature they are right now. Still deciding how much I am willing to spend on the amp.
Just a very very silly question:
Is it possible to add an resistive load on the output and use the OTL amp for IEMs? I use to DIY some connectors for putting my HD800 aside with my T1 to compare sound in HDVD800 balance output. Not sure they will make the OTL tube sounds better on IEM though.
There's more of a problem with OTL amps and low impedances than just lack of current. OTL amps must use output coupling capacitors to filter out the DC high voltage. Unfortunately, the impedance of a headphone load combined with the output coupling capacitors form what's known in electronic theory as an RC circuit (Resistance-Capacitance circuit). This type of circuit is frequency-dependent on whether it allows current to flow. IOW, for given ratings of the capacitors and the impedance of the headphones, the circuit will filter out the bass frequencies.
OTL amps usually have output coupling capacitors that are sized (~220uf) to keep the bass frequencies unharmed for 300-ohm headphones, not 32-ohm. With typical 16-ohm IEMs, expect to start losing bass at 200-400 Hz. By the time you hit 20 Hz, response will be down by 7-8 dB.