F-6 Board + Transformer Kit
As shown in the photograph above, this is a package that contains the F6 PCBs and a pair of the Jensen JT-123-FLPCH signal transformer.
These F-6 Clone Boards use the same circuit as the Nelson Pass / diyAudio Firstwatt F6 described in the diyAudio Firstwatt F6 thread.
This set of circuit boards will make a Mosfet version of the F6 amplifier of Nelson Pass. This amplifier is a new and interesting developmant from his creative mind, where a small collection of parts comes together to make amazing, beautiful music. This creativity and solid engineereing has kept Mr.Pass, and his companies, Pass Labs and Firstwatt at the forefront of specialist audio engineering and construction, where new and wonderful creations are made.
The original amplifier utilized extremely rare power Jfet from SemiSouth, which will never be made again, and are all gone. Be warned, any Ebay sources claiming to have the SemSouth devices are fakes. If you happen to already have the power Jfet, they can be used with this PCB.
Populate these boards with your components, then add your own power supply, chassis and heat sinks to complete the amplifier.
The F6 is a Class-A, Mosfet power amplifier, with a Jfet driver stage. It utilizes a small-signal transformer for phase inversion, so both the output Mosfet are N-channel. This transformer greatly contributes to the overall sonic character of the amp which is very highly regarded and considered to be similar and having all the benefits and positive characteristics of a tube amp... making some observers speculate that much of the positive 'tube amp' sound is the transformers, not the tubes. The F6 is a regular kind of amp - a voltage source amplifier, requiring nothing out of the ordinary from the preamp or the speakers.
As with most of the Firstwatt amplifiers the power output is 25WPC into 8 ohm. More into 4 ohm.
A Bipolar power supply of (+/- 24V) is required. This will require an 18V+18V (or 36V Center Tapped) transformer from 300-400VA, (shielded transformers are prefered) and PSU capacitance of at 60,000uF per rail or more. A PSU for the F4, F5, or similar will be appropriate. See the build guide for details.
Chassis (heatsink) requirements
The 4U 'Jack of all Chassis' is ideal for this amplifier. If making your own chassis a good rule of thumb is at least 25sq inch (160sq cm) of finned heatsink per output transistor. (More is always better.) The diyAudio "Universal Mounting Spec" (UMS) is a common mounting pattern between the amplifier PCB and the heatsinks. If you utilize the UMS on your heatsinks or use one of the pre-drilled chassis from diyAudio, you will be able to quickly and easily mount different amplifier boards in the same chassis. For example, a 4U 'Jack of all Chassis' with a 400VA, 18V+18V transformer and PSU board, will give you a power supply and chassis where you could try the F4, F5, F5C, Aleph J, and other Pass/Firstwatt amps in the future merely by swapping the amp PCB. The investment in Chassis and PSU needs only be made once.
An Illustrated build guide showing all sorts of useful information on how to build the F6 can be found here - Build Guide
4days to Vietnam. Thanks
I have purchased several items from the DIY store and it's all been top quality. A few masking errors on boards but they are always well explained in the forums and I know it's not the stores fault. I will be buying more...question is whats the next project?
The kit is a simple kit and sounds great. This is a great amp for someone who is wanting to get started in amp building and the delivery was great as always.
The boards work great and I received everything very quickly!
The F-6 board, PSU board, FETS, MOSFETs were all delivered quickly, well packed, and just superb quality. The case is excellent, nicer than the F-6 case. I am extremely pleased with everything from the diyAudio store. I am enjoying ordering the remaining parts and putting this together. I look forward to listening to it soon.
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