F6 Illustrated Build Guide

[jameshillj]

Thanks guys, much appreciated, especially finding them on eBay! And yes, I do tend to get a bit 'anal' about some of the details - it's a 'sort-of' challenge, or a puzzle! (I think there's a name for people like me!)

I did find a couple of different types of spring tension washers suitable for an M3 screw on the net (fitted between the screw head and the large 'penny washers') and am a bit undecided about the pressure to apply to the transistors - there seems to be a range between 2.5lbs and 7lbs - I've only looked at McMasters Carr and the MSC company - quite a range.

The transistor clips I've used apply are specified at 60N (about 10lbs) but I think it's a lot less in practice.

Working on Salas's L-Adapter to drive the F6 amp, biased to about 1.7A - going a bit overboard but ...

 

[TungstenAudio]

Something else to consider is using a torque screwdriver to get reliable and consistent torque on the M3 screws which attach the Mosfets to the heat sink. They aren't cheap, but are a good investment.

 

[ColinA123]

Something else to consider is using a torque screwdriver to get reliable and consistent torque on the M3 screws which attach the Mosfets to the heat sink. They aren't cheap, but are a good investment.

But what torque sounds best?

 

[Yaho]

Something else to consider is using a torque screwdriver

Something I've never considered. For tubes, I just have to push them in tight and wiggle a little. What would be an ideal torque?

 

[TungstenAudio]

I use 8 in-lb mounting torque. Max is usually 10 in-lb. The datasheet will have this in the Maximum Ratings section.

 

[Yaho]

The datasheet will have this in the Maximum Ratings section

And the date sheet says, Mounting 6-32 or M3 screw Torque 10 lb
I had no idea. I learned a new thing. Thanks so much!

 

[chede]

For large washers, you can also search for "fender washers" ...

For securing the bolts, I usually stick with split washers nowadays ... though, the best and proper thingies to use would be Belleville washers.

Best regards,
Claas

 

[jameshillj]

Thanks James and everyone - that pretty much gives a "ball park" tension range - some of the cheaper torque screwdrivers start about the 5 inch lb range.

I found some of the 3mm "penny washers" (thanks Colin) and the Belleville 'triple wave' washers seems a good way of doing things if there's not enough space for the clips.

 

[Yaho]

SOS
My Deluxe 4U steel is in SOMMA LOMBARDO, IT, and scheduled to arrive on this Friday. I am putting my boards together. All the parts are in and I am almost done. BUT! I just realized that I bought the zeners in pairs of 5.1v, 5.6v, 6.0v for Z1, and Z2 instead of quades (4). My question is do the value of Z1 and Z2 have to be same? Or can i mix match. In other words can the value of Z1 be 5.1V and the value of Z2 be 6.0 V?

thank you

 

[TungstenAudio]

Funny, and certainly not a disaster. Use the higher voltage zeners, and match the voltage in the same type of location across the two channels. So, pull-up bias networks get one voltage, and pull-down networks get another. Or save the zeners for another project and get 12 green LEDs to use in their place.

 

[Yaho]

Use the higher voltage zeners, and match the voltage in the same type of location across the two channels. So, pull-up bias networks get one voltage, and pull-down networks get another.

Just to be clear.

5.1v for Z1 for both boards.

6.0v for Z2 for both boards.

correct?

thanks,

 

[TungstenAudio]

You’ll probably need the 5.6V zeners instead of 5.1V. Yes, that’s the idea.

 

[Yaho]

You’ll probably need the 5.6V

Got it.
Z1s 5.6v
Z2s 6v

thanks so much

 

[tamra]

Or save the zeners for another project and get 12 green LEDs to use in their place.

Do you meant 3 green LED in series instead of zenner diode? 10K for R7,R8? or adjust value?

 

[Yaho]

10K for R7,R8?[HTML]

thats what i am doing. Changing only the zener values to 5.6 or 6.  other have changed to 3k3.  But i am sticking with Mr. Pass Nelson

 

[meanie]

Look at post #1775 for using 3 led as replacements.

You need total 12 leds.

 

[ColinA123]

Perhaps worth re-quoting the original recomendation from Zen Mod.

hogwash
all we need is some simple logic
10K from 23 to 9V1 will let 1,39mA through
5K pot across 9V1 will eat 1.82mA ........... if available ....... which isn't so replace 10K with 3K3 , put 6V8 zenner and there you go that way :
3K3 will let ~5mA through , from 23V to 6V8
5K will bleed 1.36mA across 6V8 , leaving (5-1.36)mA through zenner , absolutely stable

 

[tamra]

Look at post #1775 for using 3 led as replacements.

You need total 12 leds.

Thank you.I am sorry that I did not read all.
I read this thread at least 3 times but always stopped around 120-150 pages...

 

[meanie]

Revamped as per a post by TA and 2PicoDumbs, will try bias @1.8A.
I hope to power up the next few days.

 

[LATB]

I wouldn't want to say it over in the M2X thread, but...

I switched back from my new M2X (with only a wire for the IPS) to the F6 (also with just a wire instead of the JFETs, with the Mez DCB1 driving). Turns out I ended up listening to music the whole day -- man, I really like the F6!

I'll do some listening with different input stages on the M2X later, let's see if any of them can do better than the wire... but so far, advantage F6!