Half this club is still waiting for the Linear System 74/170 duo.
Getting the P-channel right is very difficult, i gathered, the Japanese are not about to tell.
(Fab guys who speak Japanese, and have a deep understanding of the culture, are likely rare)
You can get the ones you need for an F5T build from me, for your hard labour.
UKToecutter,
I will also jump on board for this project with boards for 5 channels and some extra psu pcbs for future use.
So:
1. 10 output boards
2. 5 v3 main boards
3. 10 psu boards
Thank you in advance for all the hard work you've done till now.
I will also jump on board for this project with boards for 5 channels and some extra psu pcbs for future use.
So:
1. 10 output boards
2. 5 v3 main boards
3. 10 psu boards
Thank you in advance for all the hard work you've done till now.
still nobody asked for circular output pcbs arrangement ?
Trouble maker ....... 🙂
Well we have been going around in circles ......
Just had a look at Linear Systems web site.
They do not do a single P channel device of any flavour!!!
I think it's going to be a long wait !!!
Are those building balanced V3 with 250mm or shorter heatsink, planning to use forced air?
If not could anyone let us know plan on heatsink configuration?
Building V3 means one wants class A power and rail voltage substantially higher than those V2, so assuming 100W into 8 ohm and rail voltage substantially higher than 32V , heat dissipation per channel for balanced seems to be something like 400W per channel or more. Since stacking heat sinks on top of the other drastically reduce heatsink efficiency, I don't get how this heat dissipation requirement could be met with 1 monoblock per channel with normal "cheap" 250mm heat sinks....
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Hi,
I assume they will mount a the V3 output boards on seperate heatsinks, so 2 x 250mm heatsinks for a single channel
Andy,
I just realized that distracted with PCB details discussions with you i forgot to put myself down on the list for 2 V2 boards.😎
I just realized that distracted with PCB details discussions with you i forgot to put myself down on the list for 2 V2 boards.😎
I spoke to someone at linear systems a few days ago. They said the J74 would be in production in the next month or so.
The plan is for a bi-amped three way mains speakers using 4 F5T channels and a matching center channel. For the surrounds I'm tempted for a normal F5 build.
Hehe, at least my relaxation room will be hot all year long!
Hehe, at least my relaxation room will be hot all year long!
Now that's great news! Maybe we can build mini version of Papa's Beast with a Thousand JFETs...😀
I know that. But if those 2 heatsinnks are stacked on top of each other ( to accomodate 4 heatsinks per monoblock), it will only be effective something like 1.5 heatsinks. So the question.
My standard F5 uses 10 inch deep 12 inch high (1 inch long fins) which is just right for 60W dissipation. With same length fin, 400W dissipation will easily require something like 60 inch high heat sinks per side for a monoblock. That is not off the shelf 2 heat sinks per side... Using 2-3 inch long fin increase efficient only by fraction also. I know I'm assuming a lot here, but you get the idea...
That is what I'm planning on doing. Mounting each output board on its own 250mm sink, so a total of (4) 250mm sink per mono-block or channel. You'll want to watch your dissipation carefully though, and select your bias carefully. I'm probably only going to put around 70W into each 250mm sink, and if I use the Conrad 250mm x 150mm, that should give me around a 30 degree rise from ambient.
O.K. so you are not stacking these on top first of all.
Are you doing balanced or single ended? I'm assuming balanced, and if so, the heat dissipation per device is only about 17W? If so, it appears to me that quite low bias per FET or low rail voltage are used in such that the class A power into 8 ohm is not going to be larger than V2 spec?
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I am planning to do balanced. Right now I am leaning toward only populating either 2 or 3 FETs on each of the output boards. With dissipation in the 30W/fet range or so.
Hi Horio,
That makes more sense, but...
Definitely not trying to rail on your plan, just trying to clarify because what we communicate here to UKtoecutter is important for success of the boards he's making for all of us.
Here is what I'm wondering. If you are populating 2 FETs now then it is basically V2. If you need V3 due to high rail voltage, then depending on how high, that heat sink might not be enough. If you are planning to populate rest of 2 FETs per outputboads later on with heatsink upgrade, chances are you are going to have to replace the heat sink with not 300mm high but more like 450mm high ones. Then using 250mm board any how does not seem to be ideal for the placement of FET on the heat sinks....
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