F1 Service Manual

[Nelson Pass]

I'm sourcing all the components to build a clone, and have a question. I suppose you are using a 300VA toroid, is this correct?

Yes, it's a stock Plitron at 18 + 18 V

 

[Raka]

Thanks.

just for curiosity, which type of 1uF have you used? I'm surprised to see such a small footprint.

 

[Nelson Pass]

I found them in a dusty box on the back shelf, labeled

--- CRAPPY CAPACITORS - DO NOT USE ---

and I got a good deal on them.

 

[jacco vermeulen]

Now, that is funny !
I just stumbled over a dusty box with 63 volts MKP caps of the same value, with LeClanché written on it.
Turns out to be a trendy froggy brand nowadays.

Oh well, back to retrieving the X1000 on the 5,376,899 Patent

 

[Raka]

I found them in a dusty box on the back shelf, labeled

--- CRAPPY CAPACITORS - DO NOT USE ---

and I got a good deal on them.

Really?

What a coincidence! I have a lot of those capacitors! I was told "Crappy" wass a daughter company of a very well known cap manufacturer, that was sold because of it's bad marketing.

 

[Ipanema]

Hi,

I have an old Coral Flat8 in a big fat bass reflex enclosure. Wonder if anyone have tried the transconductance amplifier with this driver?

Regards.

 

[BTW]

Hi,

I have an old Coral Flat8 in a big fat bass reflex enclosure. Wonder if anyone have tried the transconductance amplifier with this driver?

Regards.

Yup, we've tried the Flat 8 in BR with a F2 clone... Excellent sound overall... The extension of the bass and the bass control is really outstanding. Do build one if you can.

 

[Ipanema]

Hi BTW,

Interesting. Would you like to share your enclosure design and also speaker compensation circuits that you use?

Regards.

 

[BTW]

Hi BTW,

Interesting. Would you like to share your enclosure design and also speaker compensation circuits that you use?

Regards.

Hi Ipanema,

The Coral Beta 8 box works well enough for the Flat 8. Currently not using any compensation circuits, the bass is already excellent..

 

[Nelson Pass]

Current-source amps seem to be moving from the "dismissal-
by-experts" phase to the "early-cashing-in" phase.

There are two more companies offering product for sale.

Of course I remember one (unnamable) expert announcing that
the Zen was a joke I perpetrated on the audio community.

 

[Blues]

Of course I remember one (unnamable) expert announcing that
the Zen was a joke I perpetrated on the audio community.

"...and the last laugh baby is yours..." -Mark Knoffler and Van Morrison

 

[cyliew]

Good day,

I am confused with the schematic and pcb layout of F1. In the schematic, R6 and R8 will bias the Q2 to 7V at place where R4 meets Q2. But in the pcb layout, R6 and R8 are connected to junction where R4,C2 and Z2 are connected.Could someone please tell me which part is the correct one?

Thanks.

 

[Nelson Pass]

It doesn't matter - both work identically.

 

[cyliew]

Hi Nelson,

Thanks for reassured me by answering my doubts.

Cheers.

 

[Raka]

Nelson, the rating of some of the resistors is actually a bit "generous", is there any technical reason for that ?

 

[cyliew]

Another question about F1. Do I need to match those MOSFETs?

cheers.

 

[jh6you]

Matching is always considered better.

In my case, I did not match them and got offset voltage some what higher than 50mA. I reduced it by adding a risistor in parallel with one of the bias resistors, as advised in the F1 service manual.

Good luck!

Regards
jH

 

[Nelson Pass]

Nelson, the rating of some of the resistors is actually a bit "generous", is there any technical reason for that ?

You never run anything near their ratings. I like 20-30% of
thermal ratings, so I never get into trouble.

 

[Blues]

Nelson, the rating of some of the resistors is actually a bit "generous", is there any technical reason for that ?

Nelson has always been generous.

 

[cyliew]

In my case, I did not match them and got offset voltage some what higher than 50mA. I reduced it by adding a risistor in parallel with one of the bias resistors, as advised in the F1 service manual.

JH, thanks for the tips. Will try to match them before use.
Cheers.