F6 Illustrated Build Guide

[JimM]

I have not had a problem with turn on thump, and this is with 93 db efficient speakers.

 

[audioexplorations]

same here with 95dB.

 

[Bare]

Thank you.. Any views on Soft start?

 

[2 picoDumbs]

What's wrong with Nelson's thermistor soft start arrangement.
If he's happy using that in firstwatt products, I'm certainly happy using it in diy projects.

 

[drpro]

Just wanted to share a bit of acoustical fireworks for playing through your Pass amplifiers.
"Escape from Taiwan" by Johnny Staats. I have been playing this through my BA-3/F6 combo. The videos on Youtube are amazing. Another awesome group is the Fox Tower Band out of Germany.

 

[Bare]

Absolutely Nothing.. I would imagine.
Remember: Komplete Newbie.. If I had the requisite knowledge, I wouldn't need to be asking
So these cl60 's are the soft start?

 

[Soundhappy]

So these cl60 's are the soft start?

Yes

 

[grimberg]

Bare,

Look at the bottom of the page linked below:

http://www.plitron.com/news/technical-notes/

The section called Inrush Current explains the need for the soft start. This type of technical note is available from many transformer manufacturers. Here is another example.

http://www.avellindberg.com/transformers/tech_notes/tech_notes13.htm

 

[Bones13]

Bare,

Look at the bottom of the page linked below:

Design Notes and Efficiencies | Plitron

The section called Inrush Current explains the need for the soft start. This type of technical note is available from many transformer manufacturers. Here is another example.

http://www.avellindberg.com/transformers/tech_notes/tech_notes13.htm

I put a soft start circuit on my Aleph J, and it seemed appropriate since I upsized the transformer to 400 VA. (this is consistent with the Plitron writing)

Considering staying with 300VA for the upcoming F6 build. (using the Nelson Pass circuit as drawn) The momentary switch circuit PCB I obtained has the soft start on it, and I will probably use it too, although a couple of thermistors sure looks simpler and cheaper.

 

[drpro]

I have been using 500va transformers in my three builds, even though the F4/F6 are happy at 300VA. So each one has the DIY Store softstart board in them

 

[Bare]

although a couple of thermistors sure looks simpler and cheaper.

Seems so to me as well.
Struck me as Odd.. to clutter up an elegantly minimalist design with redundant add - on features.
But I had too little knowledge to dismiss those offhand.

Thanks once again gents.. Until I trip over yet another 'inevitable' obstacle.

 

[JimM]

Go for the thermistors it is an easy fix and if doesn't work for you then add the additional circuits / boards. I have not had any any indication of a large surge to charge the power supply.
JimM

 

[2 picoDumbs]

I'm running 400VA with 528000 uF of capacitance with thermistor soft start.
No issues here.

 

[Dennis Hui]

Another data point: For an Aleph 30, I used a 500VA transformer with
about 240000 uF cap with a thermistor soft start. It's been working well
for over 13 years.

Dennis

 

[eriksquires]

Sorry if this is the wrong place to ask. I really want to build a pair of F6 channels. Has anyone found suitable mono enclosures? I happen to have the perfect speaker stands to sneak an amp in underneath.

Thanks!

Erik

 

[2 picoDumbs]

I'll take a picture of one of mine I'm working on a bit later

 

[2 picoDumbs]

Sorry if this is the wrong place to ask. I really want to build a pair of F6 channels. Has anyone found suitable mono enclosures? I happen to have the perfect speaker stands to sneak an amp in underneath.

Thanks!

Erik

I have a larger mono case but may as well start with smallest one.
This one easily dissipates 80W. Good enough for one F6 channel.

 

[eriksquires]

That looks good, but may I have a link to buying one?

Best,

Erik

I have a larger mono case but may as well start with smallest one.
This one easily dissipates 80W. Good enough for one F6 channel.

 

[2 picoDumbs]

That looks good, but may I have a link to buying one?

Best,

Erik

I built it myself, using 2 x MF30-1F-75 per case.
Conrad Heatsinks - Products

But you can request a custom order from modu
asking for the appropriate size cases for your requirements.

 

[Milkduds]

I started populating my F6 boards this weekend and I have a couple questions:

1) Is the Aavid Thermalloy Thermal Interface Model 4180G ok for connecting the mosfet to the heat sink? It is a thick aluminum oxide piece. I bought from Mouser. If so, is the heat transfer cream necessary for this part?

2) How many builders are building the 2nd variable harmonic version? I'd like to know if it is worth the trouble to add the outboard pot or just build the standard diy version.

3) What is the size of the fender washer used to compress the mosfet to the sink, or does it matter?

TIA,
Jim