I totally agree with you Colin. I've purchase one of the 8 sets of LSJ74's (B grade) from the store front here and got three nicely matched sets out of the eight. I'll get LSK170's when available and probably swap out parts with what I've got installed currently. I'll be curious to see if I can tell a difference.
Finally completed my F6 build. Simple AC degeneration version, with 6.2v for zeners and 3.3 kohm for r7/r8. Biased around 600mA, heatsinks at 51 degrees celsius - though it is cool today (26 degrees in the tropics). Running it in using direct output from an iphone earphone jack - sweet.
Appreciate it if the experienced diyers can share their thoughts on speaker protection for F6 - looking at the minimal number of part, my immediate thoughts are that there are fewer points of failure, lowering the risk. But there's always Murphy's law....
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Appreciate it if the experienced diyers can share their thoughts on speaker protection for F6 - looking at the minimal number of part, my immediate thoughts are that there are fewer points of failure, lowering the risk. But there's always Murphy's law....
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Alvin,
Your yellow Fluke voltmeter shows 0.6V or 600mV. I am assuming you used 0.47 ohms for R2. Judging that those 2 variables are accurate, then:
0.6V/0.47 ohms = 1.28 A bias.
I am also assuming your other blue voltmeter is showing the D.C. Offset which appears to be low enough.
Best,
Anand.
Your yellow Fluke voltmeter shows 0.6V or 600mV. I am assuming you used 0.47 ohms for R2. Judging that those 2 variables are accurate, then:
0.6V/0.47 ohms = 1.28 A bias.
I am also assuming your other blue voltmeter is showing the D.C. Offset which appears to be low enough.
Best,
Anand.
Last edited:
That's correct. DC offset was fluctuating from 0 to 5mV, depending the temperature. Will probably need to check it again after a week, but i think i can live with 5mV max.
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It will depend on the efficiency of your speakers. I have modified Klipsch LaScala's rated at 103 db and my manual suggested 1 1/4 amp fast blow. I use a 1 amp fast blow and it never blows with music. If I drop my turntable arm it will. From memory most speakers in the 85 db range use 3 amps but do some research before choosing because my memory could be wrong.
Mouser https://www.mouser.sg/Search/Produc...tualkey57280000virtualkey941-C503BBCNCV0Z0461
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C1 & C2 connections
I have a question on the routing of the two, C1 & C2, 220uF capacitors.
I've seen some schematics that show the - ,negative pole, of C1 connected to the output and C2 connected to the negative power supply?
For instance this post in F6 with PCF, (also, elsewhere)
http://www.diyaudio.com/forums/pass-labs/288725-f6-pcf-2.html#post4676475
should the caps be connected that way or to the junction of the mosfet/SemiSouth sources and the resistors, R11 &R12?
The store PCB for the F6 have the caps - going to the mfet/resistor junction.
If it is connected as in the post above, what difference operationally/sonically does it make?
Also, I've noticed some recommend no source resistance or only on the bottom source and none on the top source, SemiSouth FETs, f.i. poster BUZZ.
I have a question on the routing of the two, C1 & C2, 220uF capacitors.
I've seen some schematics that show the - ,negative pole, of C1 connected to the output and C2 connected to the negative power supply?
For instance this post in F6 with PCF, (also, elsewhere)
http://www.diyaudio.com/forums/pass-labs/288725-f6-pcf-2.html#post4676475
should the caps be connected that way or to the junction of the mosfet/SemiSouth sources and the resistors, R11 &R12?
The store PCB for the F6 have the caps - going to the mfet/resistor junction.
If it is connected as in the post above, what difference operationally/sonically does it make?
Also, I've noticed some recommend no source resistance or only on the bottom source and none on the top source, SemiSouth FETs, f.i. poster BUZZ.
Hi,
Planning my next FW build, which will be the F6 to be used with 4-inch full range back loaded horn speakers with subwoofer supplementation.
Is it wise to use a Deluxe 5U chassis for optimal spacing of power supply components away from the input transformer and input components, or will the Deluxe 4U provide adequate space with careful layout as noted in some of the builds online, for quiet performance in 96-98 db/w speakers?
Thanks,
Matt
Planning my next FW build, which will be the F6 to be used with 4-inch full range back loaded horn speakers with subwoofer supplementation.
Is it wise to use a Deluxe 5U chassis for optimal spacing of power supply components away from the input transformer and input components, or will the Deluxe 4U provide adequate space with careful layout as noted in some of the builds online, for quiet performance in 96-98 db/w speakers?
Thanks,
Matt
I built a dual mono F6 with 2 x 400 toroids in the deluxe 4U chassis and it is totally dead silent with my ear to the speakers - but that is on 86dB SPL speakers (Quad electrostatics), I'll add pics.
PS, the handles come from the local hardware store, they are kitchen cupboard handles, $18 each - a bargain I thought!
PS, the handles come from the local hardware store, they are kitchen cupboard handles, $18 each - a bargain I thought!
