F-5 boards

Jump to Latest
L

labjr

Member
Joined 2003
jeffharr said:
I purchased two of the V2.0 boards from the store, never dreaming that they wouldn't have provision to adapt to the latest schematic.

I understand that P3 isn't on the board, that's not an issue. The issue is being able to stuff the board from the most recent schematic on which the part numbers are different from the original, and the circuit has changes as well.

The store shows the original schematic, but does nothing to help this situation.

I want to build the most recent schematic but could sure use some help with an updated stuffing guide, otherwise I guess I should return the V2.0 boards and look for a more recent design?

Sure would appreciate some help with this; every other purchaser must face the same dilema!

Jeff
Click to expand...

I bought the boards too, but haven't had a chance to figure which traces to start cutting. I wish I didn't have to hack up the boards.

I think the F5 circuit in the F5 Turbo manual is the most recent version. So the resistors on the input are different values and have to be reconfigured, The thermistors need to be moved from the rails to the points between R7-Q3 and R8-Q4. And P3 added.
 
JojoD818

JojoD818

Staff Emeritus
Joined 2003
geocities.com/jojod818/index.html
jeffharr said:
I purchased two of the V2.0 boards from the store, never dreaming that they wouldn't have provision to adapt to the latest schematic.

I understand that P3 isn't on the board, that's not an issue. The issue is being able to stuff the board from the most recent schematic on which the part numbers are different from the original, and the circuit has changes as well.

The store shows the original schematic, but does nothing to help this situation.

I want to build the most recent schematic but could sure use some help with an updated stuffing guide, otherwise I guess I should return the V2.0 boards and look for a more recent design?

Sure would appreciate some help with this; every other purchaser must face the same dilema!

Jeff
Click to expand...


Hi,

The BOMs that correspond to that board has already the updated parts values. As you have noticed, the most recent iteration of the circuit has different part numbering, but the latest values have already been changed in the BOM. SO if you follow the BOM, you are actually building the latest version.

Thanks
 
JojoD818

JojoD818

Staff Emeritus
Joined 2003
geocities.com/jojod818/index.html
labjr said:
I bought the boards too, but haven't had a chance to figure which traces to start cutting. I wish I didn't have to hack up the boards.

I think the F5 circuit in the F5 Turbo manual is the most recent version. So the resistors on the input are different values and have to be reconfigured, The thermistors need to be moved from the rails to the points between R7-Q3 and R8-Q4. And P3 added.
Click to expand...


The new values are already published in our BOM which is linked to from the product page. The location of the thermistors (one of it's leads) being on the transistor side rather than the rail side has of little to no difference at all in it's performance.

P3 can be added "off-board", but I was under the impression that one needs a distortion analyzer to perfectly adjust this. It wouldn't make any sense adjusting this by ear and everyone has this tool so maybe it makes more sense to leave P3 at the moment.

Cheers
 
Last edited by a moderator:
L

labjr

Member
Joined 2003
JojoD818 said:
As I've said, the new values are already locked in the BOM. The location of the thermistors (one of it's leads) being on the transistor side rather than the rail side has of little to no difference at all in it's performance.

Cheers
Click to expand...

Then why did Nelson change the circuit?


JojoD818 said:
P3 can be added "off-board", but I was under the impression that one needs a distortion analyzer to perfectly adjust this. It wouldn't make any sense adjusting this by ear and everyone has this tool so maybe it makes more sense to leave P3 at the moment.

Cheers
Click to expand...

So why even build the circuit then?
 
JojoD818

JojoD818

Staff Emeritus
Joined 2003
geocities.com/jojod818/index.html
labjr said:
Then why did Nelson change the circuit?
Click to expand...


I believe it is so to take into account the voltage drop in the resistor.

I did say it has little to no difference at all because imho it is a minor "change the circuit" thing but I now realize this may mean the world to others and so it (the board) can still be configured to follow suit.



So why even build the circuit then?
Click to expand...

P3 was, as I understood it, added to completely minimize the effects of non-match jfets that may lead to distortion. Without P3, the amplifier still behaves and performs as published. It is therefore left to the builder if he/she will build it with or without P3.
 
L

labjr

Member
Joined 2003
Part of getting the best sound out F5 and other amplfiers is tweaking for different amounts of harmonic content which make up it's characteristic sound. It's the small things that make a difference in the character. Otherwise we'd be better off building a chip amp. Solder one chip on a board and be done with it.

So to say it makes no difference, seems like you are not impartial because the boards you have here don't have those changes.
 
JojoD818

JojoD818

Staff Emeritus
Joined 2003
geocities.com/jojod818/index.html
labjr said:
Part of getting the best sound out F5 and other amplfiers is tweaking for different amounts of harmonic content which make up it's characteristic sound. It's the small things that make a difference in the character. Otherwise we'd be better off building a chip amp. Solder one chip on a board and be done with it.

So to say it makes no difference, seems like you are not impartial because the boards you have here don't have those changes.
Click to expand...


I meant the thermistor, not the P3. And like I said, P3 can still be employed easily by just bending the leads of the trimmer and soldering it on top of the board.
 
Variac

Variac

diyAudio Editor
Joined 2001
BurningAmp.org
Paid Member
bugzbunny said:
Hi,
I hope the diyaudio store is not waiting to see how the Mayan thing unfolds before deciding to release the F5T V3 boards...:)
Do we have a tentative date on when these will be available in the store?
Click to expand...

Yeah, we're waiting for the end of the NEXT 1000 year cycle.
NO! The boards are made and I believe have shipped. Should make it to my house soon. Perhaps before Christmas. Then I have to separate and package them and send them to the order fulfillment people in LA. So we're now talking about 2 wks..
 
Last edited:
Variac

Variac

diyAudio Editor
Joined 2001
BurningAmp.org
Paid Member
labjr, you have your opinion, we have our boards. We've explained that the P3 option can be implemented. You don't like that approach. The boards we have are the boards we have. We like them, you want something different. We have certainly heard your suggestions and will consider them all. Really. But further arguing is not productive.

labjr said:
Part of getting the best sound out F5 and other amplfiers is tweaking for different amounts of harmonic content which make up it's characteristic sound. It's the small things that make a difference in the character. Otherwise we'd be better off building a chip amp. Solder one chip on a board and be done with it.

So to say it makes no difference, seems like you are not impartial because the boards you have here don't have those changes.
Click to expand...
 
Last edited:
N

No 4

Member
Joined 2011
I ordered a pair of boards Thursday and received them today, Monday! Thanks for the quick turn around! They look great, very nice quality......

I also ordered several matched pairs of the elusive 2SK170BL/2SJ74BL for this project and any future projects that may arise from this endeavor.

Thanks to all at diyaudio
 
You must log in or register to reply here.
Top Bottom