OddBlock High Output Series 1

OddBlock High Output Series 1

OddWatt Audio is proud to announce the long awaited arrival of our OddBlock High Output Series 1 or OBHO mono block single channel power amplifier kit.

The OBHO shares most of the OddBlock Series 2 Octal’s highly regarded schematic design and performance specifications with a few very large exceptions. Two of these being the use of TUNG SOL’s monster KT120 power tubes generating a thunderous 45 watts of pure class “A” power @ less than 2% THD and having a maximum output of 55 watts. Class “A” mode of operation being forced by the use of a constant current source in the output stage.

Adding to the quality, the OBHO also features the same NOS 12SL7GT as the ODDBLOCK Series 2 OCTAL in the driver stage. The OBHO’s deliver outstanding power and exhibit superior sonic qualities delivering clear, deep and very articulate mids and highs with a huge sound stage with incredible performance and control being heard in the low frequencies with sub audio response which is flat to 10HZ. The OBHO’s are capable of driving difficult load loud speakers such as electrostatics that exhibit a highly capacitive load like Martin Logan Vistas as well as more conventional speaker systems with ease.

The OBHO kits are a mono block or single channel amplifier with two kits being required for stereo operation.
Although the OBHO uses the KT120 for maximum power output, the OBHO can be used with alternate octal base power tubes such as the 6550, KT88 and KT90’s. With a flick of a switch and a quick tube balancing operation you are ready to enjoy. The use of the mentioned alternative power tubes will yield a maximum output of approximately 25 watts verses the 45 to 55 watts output with the KT120 power tubes. We are very pleased with the listening results using the JJ KT88 power tubes in these amps.

Note: We do not recommend the use of ELECTRO-HARMONIX KT88 in these units.

Like the OddBlock Octal’s a feed back loop defeat switch is also provided for the purist at heart. OBHO utilize a very low amount of feedback, generally 3-4 db so switching to feed back defeat position can be slightly heard. We have found with these amplifiers that the use of 0 feed back results in a very pleasing result in some circumstances so we encourage experimenting with your system. Low noise, low distortion and maximum bandwidth were foremost in the design of these amplifiers. Power output was secondary but with the availability of the KT120 power tube we feel a very respectable level of both fidelity and wattage has been achieved with the OBHO design.
Most contemporary amplifiers seem to be involved in a horse power race. Bigger is better seems to be the mantra. Often sound quality in the lower power levels is sacrificed to get greater output. All OddWatt kits are designed to deliver optimum response at actual listening levels which are often only a few watts.
A feature that many will like is that when overdriven the amplifiers overload gracefully. There is no sudden massive distortion as is common in many solid state amplifiers. The OBHO comes complete with all parts to have a fully operating amplifier kit when completed including a metal top cover. We do recommend using the top cover as the KT120 power tubes emit a large amount of heat. Serious burns can result from contact with these tubes while the amplifiers are in use so please be careful.

Typical operational results if used with TUNG SOL KT120 power tubes

Rated Power output 45 watts RMS
- Distortion below 0.5% through half power, 1% at full power*
- Frequency Response 8HZ to 20 KHZ +0/-1db at any rated power*
- Signal to noise better than 85 db
- Tubes TUNG SOL KT120, NOS 12SL7GT
* Typically below 0.3%

Typical operational results if used with JJ KT88 power tubes ( JJ KT88 power tubes sold separate of OBHO kits)

- Rated Power output 25 watts RMS
- Distortion below 0.5% through half power, 2% at full power*
- Frequency Response 8HZ to 20 KHZ +0/-1db at any rated power
- Signal to noise better than 85 db
- Tubes JJ KT88, NOS 12SL7GT
* Typically below 0.3%


OBHO – One complete kit supplied with TUNG SOL KT120 power tubes with one 12SL7GT pre-amp tube $1095

TO ORDER ONE OF THE ABOVE KITS send us an email at sales@oddwattaudio.com stating the product you would like from the list above. Include the product code of your choosing such as "OBHO" in your email. Please state the amount you would like and include your shipping address so we can quote shipping for you and give you a total cost.
ACCEPTED PAYMENT TYPES - ODDWATTis unfortunately unable to take direct credit card payments however we accept PayPal, direct money transfers or checks or money orders from major US banks. Please specify how you would like to pay in your email. We do charge the customer applicable fees on PayPal and direct money transfers. We are happy to answer any questions you may have about our products or application of our products. Questions can be sent also to sales@oddwattaudio.com. GOOD LISTENING - OddWatt