Is anyone building the DIY Pass F-5

Russellc · « **Reply #140 on:** 28 Mar 2011, 07:14 pm »

I got it and have replied if you want them. I would seriously consider the Toshibas however. If you cant wait, order a set from Blues. You will have them in 2 days flat!
Also, I believe these Fairchilds are matched, so you would likely want to change the good one out anyway. Really there is no need to operationally, just I like BOTH channels to be identical as well!

Russellc

strider · « **Reply #141 on:** 29 Mar 2011, 12:15 am »

Ordered the Toshibas from Blues at diyAudio this evening. Almost went with four of each to make use of the doubled output positions of my boards, but I've done drained my audio account from blowing things up. Still (from Sunday) have a PM in to ZhouFang for the Jfets and more MOSFETs, maybe by the time he responds I'll have adequate funds to double down.

Also have some stranded wire, short standoffs, and more fuses on the way. Mr. Mouser may be able to retire sooner then he thought.

Russellc · « **Reply #142 on:** 29 Mar 2011, 01:43 pm »

good news on the mosfets. Are the J-fets smoked? Or can they be used.

Russellc

strider · « **Reply #143 on:** 29 Mar 2011, 04:20 pm »

Fingers are crossed on the Jfets. Guess I should check them, though.

sts9fan · « **Reply #144 on:** 29 Mar 2011, 04:39 pm »

So what did you do? Have the trim pots at zero ohms or the highest setting? When read your pots what is the highest you can get? Mine only seem to get to 1.2K but I figure that is the circuit.

strider · « **Reply #145 on:** 29 Mar 2011, 06:37 pm »

Quote from: sts9fan on 29 Mar 2011, 04:39 pm

So what did you do? Have the trim pots at zero ohms or the highest setting? When read your pots what is the highest you can get? Mine only seem to get to 1.2K but I figure that is the circuit.

The highest reading I get across the trim pots is about 1.2k, which I believe is due to having the 2.2k resistor (R3/R4) in parallel with the 5k trimmer. Right now, on the board with the fried MOSFETs, P2 is set to the highest and P1 is set to zero. I think we set those before I left my in laws house, but with the different readings I'm having some doubts. Either way, by putting a 100 ohm power resistor in series with V+ and V- coming into the amp board, the voltage is limited enough so it's not enough to damage anything in event of the trimmers being adjusted incorrectly.

Measured the Jfets on the board that got zapped, read the same as the good board

Russellc · « **Reply #146 on:** 29 Mar 2011, 09:16 pm »

If you can come up with a variac, it is MUCH simpler, and safer. Also if you can fire up one channel, then the next.

Russellc

strider · « **Reply #147 on:** 29 Mar 2011, 09:22 pm »

Quote from: Russellc on 29 Mar 2011, 09:16 pm

If you can come up with a variac, it is MUCH simpler, and safer. Also if you can fire up one channel, then the next.

Russellc

Two other things my FIL clued me in on. Next time, headed to his house before I turn on the main switch.

Russellc · « **Reply #148 on:** 30 Mar 2011, 01:33 pm »

The variac is very usefull. You can keep voltage low, so the bias will be too, and you can safley see which way which pot will raise/lower the bias. At this low level you can zero the output dc, then ramp up voltage, check and adjust bias, ramp up a little more, check/adjust bias and so on. Prevents those full throttle accidental startups, or accidentally upping the bias through the roof.

Russellc

Russellc · « **Reply #149 on:** 31 Mar 2011, 08:37 pm »

There are a few builders I've seen who are having similar troubles with power supply. I think some of this confusion comes from the FirstWatt schematic, which uses the more modern schematic protocol that does not show "loopovers" but just has the wires crossing, and connection if any denoted by a dot there. On the FirstWatt power supply schematic it shows this on the primaries where the thermistors connect "crossing"....they indeed do crossover, there is not a connection there! if soldered at this point Ican see where some trouble would lie. See this thread: (post 406-420) http://www.audiokarma.org/forums/showthread.php?t=340873

Hope this helps somebody...

Russellc

sts9fan · « **Reply #150 on:** 31 Mar 2011, 09:24 pm »

Well, I just fixed my PS. I had my secondarys mixed

I guess I should have her up and running soon!!

Russellc · « **Reply #151 on:** 1 Apr 2011, 01:23 pm »

Have you fired up?

Russellc

JoshK · « **Reply #152 on:** 1 Apr 2011, 02:26 pm »

Slight tangent, but has anyone had the opportunity to compare the F5 to one of the single ended designs such as the Aleph J, F3 or J2? Its something I am really interested in hearing.

04dgmsilv · « **Reply #153 on:** 1 Apr 2011, 03:40 pm »

I've had a DIY F5, DIY F3 and OEM F3 in my system. I currently have the OEM F3 doing most of the heavy lifting with my Zu Essence speakers. I think it is a great combination with the ribbon tweeter, which sounds just a little rough and maybe too lit up with the F5 at times (recording dependant in many cases). The F5 does have a better grip over the bass than the F3, though not a decisive issue in my system.

I regretfully sold my DIY F3 monoblocks as they were not a kid friendly design, but I think they were the best of all three (IMO, with parts choices being the primary difference).

If you build a dual mono DIY first watt chassis/PS combo, you could always reconfigure the PS for just about any of the FW amps.

Russellc · « **Reply #154 on:** 3 Apr 2011, 09:07 pm »

Quote from: sts9fan on 31 Mar 2011, 09:24 pm

Well, I just fixed my PS. I had my secondarys mixed
I guess I should have her up and running soon!!

Are you listening yet?

Russellc

sts9fan · « **Reply #155 on:** 3 Apr 2011, 09:21 pm »

I was away for the weekend and have had no chance to work on it. I expect to have it up within a week. At that point I will have a F5 and a ZenV9 so pretty close to a F5/F3 comparison.

JoshK · « **Reply #156 on:** 4 Apr 2011, 01:06 pm »

FWIW, a more ideal comparison is the F5 vs Aleph J, as the F5 is closer to being a complementary (push-pull) version of the Aleph J (single-ended). The F3 is single-ended but its quite a bit different design altogether. Still the F3 is single ended so the harmonic differences still apply.

Russellc · « **Reply #157 on:** 4 Apr 2011, 06:52 pm »

Quote from: JoshK on 4 Apr 2011, 01:06 pm

FWIW, a more ideal comparison is the F5 vs Aleph J, as the F5 is closer to being a complementary (push-pull) version of the Aleph J (single-ended). The F3 is single-ended but its quite a bit different design altogether. Still the F3 is single ended so the harmonic differences still apply.

Actually they have little if anything in common, other than the Aleph J does use a J-fet.....Otherwise its a single ended aleph, while F-5 is P-P amp.

Russellc

sts9fan · « **Reply #158 on:** 4 Apr 2011, 07:01 pm »

I don't know anything about an ideal comparison. Ideal how? They are all apples to oranges. At least the AJ, F3 and ZV9 all use the same JFET... I think.

Russellc · « **Reply #159 on:** 4 Apr 2011, 07:32 pm »

Quote from: sts9fan on 4 Apr 2011, 07:01 pm

I don't know anything about an ideal comparison. Ideal how? They are all apples to oranges. At least the AJ, F3 and ZV9 all use the same JFET... I think.

Its all good, all Pass all the time! I have alephJ boards...sooner or later, well later as there are several infront of it!