F5 Help Needed

[woodturner-fran]

OK, looks like all those things are covered - I knew you would have, but its worth double checking (given my past experience ).


Go try what papa says!


Fran

 

[vdi_nenna]

Thank you, Fran. I appreciate your time and input.

Vince

 

[vdi_nenna]

Does the F5 need more drive than an ipod can provide? To save space my current setup is an iPod to a B1 to a gain clone. I have a BOZ and BLS in storage.

Thx,

V~

 

[CBRworm]

No, an iPod can drive an F5 quite loudly.

 

[vdi_nenna]

No, an iPod can drive an F5 quite loudly

That's what I was afraid of.

Also, replacing R3 & 4 with a 3.3k resistor brought the bias voltage closer to .59, but not close enough. It gets up to about .50, then drifts downward. Still no DC at output. Might try 4.7k resistors just for fun.

Thanks,

V~

 

[vdi_nenna]

Can I use the same test gig to test P-Channel jfets as showing in post #15?

Thanks,

Vince

 

[Tea-Bag]

Can I use the same test gig to test P-Channel jefets as showing in post #15?

Thanks,

Vince

Not exactly, got to flip things around.

Check this one out.
http://www.diamondstar.de/transistor_matching_jfet.html

 

[vdi_nenna]

Thanks Tea-bag, that was quick!

 

[vdi_nenna]

Found the problem

The schematic Fig 6 shows Q3 as a IRFP9240 and Q4 as a IRFP240.

The article says, "The output MOSFETs are the IRF240 N channel type (Q3) and the IRD9240 P channel type (Q4).

I'm probably the only fool that followed the article instead of the schematic.
Can someone verify this for me?

I'm using IRFP140s and IRFP9140s.

Thanks,

Vince

 

[Tea-Bag]

Yep, that's wrong in the article. The schematic is correct.
Here is the schem sans protection circuit.

You are there now.

 

[vdi_nenna]

Finally!

I think I have it working! Got .60 across R12 and .078 DC at the output.
Approximately the same on both channel.

For a second I thought I let out the smoke out of this build!! It was just the alligator clip rubber jacket that got too close to a 3w resistor!!

This build was done on Peter Daniel's F5 amp board.

Won't check this one off as done until I hear some music out of it.

Thanks everyone.

 

[woodturner-fran]

mmmm, and I think you will find that the efforts you put in will be well worth it. Very fine amp indeed.


Fran

 

[vdi_nenna]

Pics

you will find that the efforts you put in will be well worth it. Very fine amp indeed.

I agree.

Some Pics...

http://i145.photobucket.com/albums/r216/vdinenna/Audio Projects/F5_1_Fin.jpg

http://i145.photobucket.com/albums/r216/vdinenna/Audio Projects/F5_2_Fin.jpg

http://i145.photobucket.com/albums/r216/vdinenna/Audio Projects/F5_4_Fin.jpg

 

[scranton]

F5 Problems

Thanks Tea-Bag and Vdi-Nenna. I have been through two PD amp boards and not able to get past the very first testing step with a veriac. And the reason...there may be others, that's for sure...is I did exactly what vdi-Nenna did. Swapping the output transistors. Thanks

Jan

 

[vdi_nenna]

I did exactly what vdi-Nenna did. Swapping the output transistors.

The first build is still a mystery. The build that worked was a different set of amp boards. Once I understood what was correct (schem or article) I saw that I had the FETs correctly installed.

Increasing the 2.2k resistors didn't help either.

I'm listening to the F5 and B1 right now. It's hard to describe. I can say nothing seems hidden. I've actually heard a few songs where before the lyrics were indistinguishable. Not anymore. It's like untying a musical knot.



V~

 

[scranton]

F5

Hi

I can't wait to get home to see if I can get this up and going. I got a hold of PD's gainclone kit after two tries on the F5. My hope to was to have the B1 and F5 drive my KJKing open baffles. With and Adom 555 2 and the B1, I am hearing somthing like what you are describing. I hope the F5 takes to that level. Thanks

Jan

 

[Tea-Bag]

Right now I am running F5 on top, F5 on bottom, with Open Baffles.

Lowther on top, 2 EM Alpha 15A's on bottom like mjk stuff.

I also put T-bass on the bottom end, and this brought down extension real well.
Sound is pretty pinpoint on the F5s even on the low end. Good times!

 

[vdi_nenna]

The full-range drivers are starting to interest me. They make so much sense. Haven't built one yet. Any recommendations for starters?

 

[scranton]

Lowther on top, 2 EM Alpha 15A's on bottom like mjk stuff.

I use the same 15 in woofers and only drem of Lowther. I have 6.5 inch Fostex 166esr for the high end. It is better than the 103's that MJK used first. Which lowther are you using? Like MJK?

Jan

 

[Tea-Bag]

I have DX4 lowthers with a notch filter on them. I have had them for some time. I have not heard the fostex speakers.

I hear the PM6A is not quite as detailed, but very magical and doesn't need as much or no filtering in OB.

There seems to be lots of options now for full range drivers. I am not the right person to ask.