F4 power amplifier

[flocchini]

Originally Posted by buzzforb

Hey I got one of those xformer thingies. Guess i could hook it up to F4 Toaster time!

I really like the transformer in the headphone amp I have working
It would be interesting how the modded F4 compares to your F6

[flocchini]

Originally Posted by Zen Mod

simple

ZM speaks and one channel sings. Now time to debug one is really wrong with the other. Checking connections

[flocchini]

ZM speaks and both channels sing


cold solder

Thank you again

[gl]

Last year I built a direct box for bass guitar using the F4 circuit but scaled way down to just a couple of watts. The output section used 5 pairs of irf610/9510 mosfets driving a Jensen JT-11-DMPC. The 9510's were the good old Intersil ones by the way. I used 18V rails and 50ma of bias on each transistor so I didn't use any heat sinks.

I needed to drive long lines (100-200 meters) in a number of venues where I play and this box really works well. With a gain of one and lots of output current, I don't have the 20-25 dB of loss you get with DI boxes like the JDI.

The unit uses unregulated supplies just like the big F4 and the biggest issue was hum. It took a couple of transformer swaps and a lot of tinkering with parts placement, but in the end everything turned out well.

Bottom line - the F4 circuit works REALLY well with transformer output.

I have been meaning to start a thread on this DI box project but..well...you all know how that goes.

Graeme

[flocchini]

Originally Posted by buzzforb

Hey I got one of those xformer thingies. Guess i could hook it up to F4 Toaster time!

Anybody using F4 as a bass amp?

I'm kicking around the idea of transformer interstage F4 to drive my SEAS woofers because I really get nice tight bass to the headphones

Currently using Crown K1s

[Zen Mod]

I didn't heard anyone , using F4 or derivative (BA output) , complaining about performance in bass

[flocchini]

Originally Posted by buzzforb

Hey I got one of those xformer thingies. Guess i could hook it up to F4 Toaster time!

Buzz

If/when you do this I would like to hear what you think of this relative to your BA3/F4.

Now that I have done it a few times (with help on wiring transformers correctly) I really like the sound and simplicity. As I mentioned above I would consider doing a full blown F4 with interstage transformers to see how they drive my SEAS woofers.

Thanks

Bob

[buzzforb]

If you got the gain, they got the grunt. That is biased at normal levels. If you are quazy, just bias them higher and raise rail voltage and you definitely have no issues. it is current amp, so it laughs at tough load. As for combinations, I have all boards in quesiton populated, its just matter of taking time to throw it together. I have always wanted tro try Lovoltech JFet SRPP FE for F4. Taylor it to specific Zin of jfet free F4 and you got an amp that can swing big V and shoot big I

[Piero2012]

Hello everyone, I am a new member on this forum and I write from Italy, I need your help to make an amplifier First Watt F4, draft Nelson Pass. Who can give me tips on buying the necessary equipment? It 'an existing kit of this amplifier? Thank you all for the help I will be given later, I look forward to hearing from you
Pierluigi

[Itsmee]

There are no complete kits available AFAIK,

The PCBs can be purchased from the diyAudio store, there is a link at the top of the page.

P-F4-2V20 - Pair of F-4 boards (Makes 2 channels; Rev 2.0) - Boards

A semiconductor kit can be purchased from a forum member h_a

matched Fets for your F1, F4, F5, Aleph J...

Amplifier chassis with pre drilled and tapped heatsinks will be available soon from the store.

The diyAudio Store (USA) soon to stock chassis – requesting your feedback!

Large value PSU capacitors can be purchased from forum member umut1001

50V 68000uf KENDEIL CAPS FOR SALE!!!

I have purchased from all of the above without any problems.

Welcome to the forum and happy building