Yes , thank you.. am aware of the DC offset trim.
From past experiences Bournes' are shipped at ~midpoint.
ALL is soldered in place. All that's missing is 120 Volts.
From Vssa experiences, setting bias/Ddc offset shouldn't be a problem.
I hope
Unless I've bungled a soldered connection.. somewhere.
There is Always room for a screwup.
From past experiences Bournes' are shipped at ~midpoint.
ALL is soldered in place. All that's missing is 120 Volts.
From Vssa experiences, setting bias/Ddc offset shouldn't be a problem.
I hope
Unless I've bungled a soldered connection.. somewhere.
There is Always room for a screwup.
Second what Russell has posted. I am fairly new to DIY, though built many a Heathkit in the day. I have mostly stuck with the DIY Store products. All of my transformers have been Antek, the critical transistors from the chap in Israel, Alweit is his Ebay ID. The come closely matched and are the real item. Cases have been bought through the store also. Parts mostly from Mouser and Digikey with a few from other vendors as needed. I have also tried to shop with the various merchants that post here. Apex and SoniCraft are my two favorites.
Octopart is a great website to see who has what part in stock. And Russell is right follow the guides and your Pass amp or preamp will work. Thus far I have built two F4 and one F6 amps along with a BA-3 preamp, using parts from the above vendors. They have almost always worked first time, yes I have made a few errors, corrected them and now I am enjoying Nelson Pass sound.
Octopart is a great website to see who has what part in stock. And Russell is right follow the guides and your Pass amp or preamp will work. Thus far I have built two F4 and one F6 amps along with a BA-3 preamp, using parts from the above vendors. They have almost always worked first time, yes I have made a few errors, corrected them and now I am enjoying Nelson Pass sound.
I am sourcing some resistors now and it looks like the distributors stock 100ohm 5w wirewound Welwyn W22-100RJI
Would wirewound be a good choice for the build ?
Would wirewound be a good choice for the build ?
That would be higher than I would want to go. We are talking about 32 or 33 V rails after rectification. Brave souls would try it I am sure. If my memory is correct 30V is about as high as most go. More technical savvy members can do the numbers for you where I am just speaking from what I have read.
I wouldn't use a transformer that big.
You could make a regulator set for 24-28V as shown in Nelson's Zen Variations 3 article, under the heading "a bipolar regulator for son of zen" https://www.passdiy.com/project/amplifiers/zen-variations-3 but you'd need at least 2 pair of mosfet for the regulator, and heatsinks nearly the same size as the amp.
It would be really neat to do that, but total overkill.
You could make a regulator set for 24-28V as shown in Nelson's Zen Variations 3 article, under the heading "a bipolar regulator for son of zen" https://www.passdiy.com/project/amplifiers/zen-variations-3 but you'd need at least 2 pair of mosfet for the regulator, and heatsinks nearly the same size as the amp.
It would be really neat to do that, but total overkill.
Built My light bulb tester gizmo using a 60 w bulb, disconnected power wires from PSA to amp boards.
Bulb lit bright then a second or 2 later dimmed to nothing.
Wee green Leds lit up nicely.. 24.7 V from either side of the PS outs.
Seems good to go, albeit the wee green leds stay lit for ~15 mins after power off.
So.. in setting bias efforts..what does measure across the 0.47 resistor actually mean?
Meter's Alligator clips to either end of the resistor.. Or?
Bulb lit bright then a second or 2 later dimmed to nothing.
Wee green Leds lit up nicely.. 24.7 V from either side of the PS outs.
Seems good to go, albeit the wee green leds stay lit for ~15 mins after power off.
So.. in setting bias efforts..what does measure across the 0.47 resistor actually mean?
Meter's Alligator clips to either end of the resistor.. Or?
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Yeah can use alligator clips why not and congratulations with your build.
What psu board do you use, how much capacitance?
It will definitely take a while when your caps are discharged, I got a couple of minutes for 30000uf per rail so might be longer for 60000uf))
Sent from my ONE A2003 using Tapatalk
What psu board do you use, how much capacitance?
It will definitely take a while when your caps are discharged, I got a couple of minutes for 30000uf per rail so might be longer for 60000uf))
Sent from my ONE A2003 using Tapatalk
Ermmm!?
Right channel under test/running with 60 w light bulb at medium brightness
Using the 6.2 v Z and 3.3k resistors (dunno about the Ohms from Memory only) but read/followed as Zen Mods suggestion.
Bias trimmer runs out of travel (clicks) at 0.386 V with Offset at 0 at that, but offset Bournes is also within a turn of Clicking as well
Are the 6.2v Z 's and those resistors Not allowing any higher bias ??
Device Temp is at 27 C after an hour.
Ohhh
Just realised that the Bulb tester gizmo shouldn't ?? be in circuit for this
Back to the meters to reset and try again
Right channel under test/running with 60 w light bulb at medium brightness
Using the 6.2 v Z and 3.3k resistors (dunno about the Ohms from Memory only) but read/followed as Zen Mods suggestion.
Bias trimmer runs out of travel (clicks) at 0.386 V with Offset at 0 at that, but offset Bournes is also within a turn of Clicking as well
Are the 6.2v Z 's and those resistors Not allowing any higher bias ??
Device Temp is at 27 C after an hour.
Ohhh
Just realised that the Bulb tester gizmo shouldn't ?? be in circuit for this Back to the meters to reset and try again
It's Alive!
Without Tester Bulb in Circuit
It biased /set up Foolishly easily.
0.55v.. 0.00v offset.. devices at 45C, Heatsink at 40C Seems (so far) as rock steady
Really it's embarrassingly simple.. Once one knows how
All that's missing Now is to button up and attach Speakers
Without Tester Bulb in Circuit
It biased /set up Foolishly easily.
0.55v.. 0.00v offset.. devices at 45C, Heatsink at 40C Seems (so far) as rock steady
Really it's embarrassingly simple.. Once one knows how
All that's missing Now is to button up and attach Speakers
Attachments
Thanks
Tested with a pair of DIY Mark Audio full rangers (albeit with tweets) which to be honest, never did please me.
Sounded a helluvalot better on the F6 than ever before tho.
Sounds seemed a bit thinnish on start up, good detail and presence however. Interestingly after a half hour or more of use... sounds became fuller, deeper and clearer.
Quite Nice when fully warmed up, actually.
I'm liking it
Clearly this isn't going to be an Instant on/ready to use Amp.
Small issue with my Leds. I fitted 3mm ones to 1/32" holes in the front panel. Still Too Bright, especially the green PS ones.
A wee trimmer pot fitted inline to dial in the brightness.. perhaps?
A passable idea? if so, any quick suggestions for a trimmer value ?
Testing my Tannoys .. tomorrow
Tested with a pair of DIY Mark Audio full rangers (albeit with tweets) which to be honest, never did please me.
Sounded a helluvalot better on the F6 than ever before tho.
Sounds seemed a bit thinnish on start up, good detail and presence however. Interestingly after a half hour or more of use... sounds became fuller, deeper and clearer.
Quite Nice when fully warmed up, actually.
I'm liking it
Clearly this isn't going to be an Instant on/ready to use Amp.
Small issue with my Leds. I fitted 3mm ones to 1/32" holes in the front panel. Still Too Bright, especially the green PS ones.
A wee trimmer pot fitted inline to dial in the brightness.. perhaps?
A passable idea? if so, any quick suggestions for a trimmer value ?
Testing my Tannoys .. tomorrow
Hi Guys,
I've been enjoying my F6 for several months now, but when I switched it on after 30 - 40 seconds a low hum, lower that a ground loop comes up under the music. Before it was always dead quiet. It still plays music but with a deep hum. I opened it up today to take a look and I found R4 on the left channel fried, everything else looks fine, and all looks good on the right channel. I had used 1/4 w MF resistors in this position. I'm going to order some replacement resistors 1/2w MF this time, but before I do is there anything else I ought to consider replacing ?
Thanks,
Paul
I've been enjoying my F6 for several months now, but when I switched it on after 30 - 40 seconds a low hum, lower that a ground loop comes up under the music. Before it was always dead quiet. It still plays music but with a deep hum. I opened it up today to take a look and I found R4 on the left channel fried, everything else looks fine, and all looks good on the right channel. I had used 1/4 w MF resistors in this position. I'm going to order some replacement resistors 1/2w MF this time, but before I do is there anything else I ought to consider replacing ?
Thanks,
Paul