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Old 12th September 2013, 02:45 PM   #2361
Mallard is offline Mallard  Germany
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Join Date: Jan 2003
Location: Germany, Luenen
Default FET Audio F5T Kit

Hi,

has anyone used the F5T V3 Kit from FET Audio? I know he is using a F4 pcb with only 3 pairs of output stages instead of 4. Ok the effect is to have less current and therefore less bass quality? Has this really such a deep impact on the sound quality?

What's your experience with that?

Would appreciate if someone can give a hint!

Cheers,
Mallard
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Old 12th September 2013, 02:51 PM   #2362
6L6 is offline 6L6  United States
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Location: Denver, Colorado
Quote:
Originally Posted by Mallard View Post
I know he is using a F4 pcb with only 3 pairs of output stages instead of 4
That is more output devices than a F5Tv2, therefore will give lots of bass, current, and power.

I think it would be a wonderful amp!!
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Old 12th September 2013, 03:11 PM   #2363
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I hope so... I bought two sets from him...
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Old 12th September 2013, 03:18 PM   #2364
Mallard is offline Mallard  Germany
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Quote:
Originally Posted by ijscobar View Post
I hope so... I bought two sets from him...
Ohh nice, it would be great if you can share your experiences with that!
Unfortunatelly Spencer is out of matched 2SK1530/2SJ201 and it will take till October timframe when he can sell these again.
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Old 12th September 2013, 03:24 PM   #2365
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Will share but it's a long term project i'm afraid
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Old 12th September 2013, 04:48 PM   #2366
WalterW is offline WalterW  Netherlands
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Quote:
Originally Posted by Mallard View Post
Unfortunatelly Spencer is out of matched 2SK1530/2SJ201 and it will take till October timframe when he can sell these again.
Look here: enough 2sj201 en 2sk1530 perfectly matched:
Operating Vgs and Yfs matched 2SK1530/2SJ201 for the F5, F5 Turbo and F5X

Walter
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Pass F5, F5Tv3, ACA, Aleph J, DDDAC1794, DCB1, BA3-preamp, VFET CSX1.
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Old 16th September 2013, 05:37 PM   #2367
gabsta is offline gabsta  United Kingdom
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Default my f5t saga

hello all. I have only signed up today. iam looking to make some friends and get help with my f5t build.
my friend riki started to do the electronics on this project for me and I designed and built the chassis. some of you may have seen my amp on here already when he was getting advice on here.
basic issue he blew the amp first time and set fire to it second time lol so we have some issues not sure what though. I will post as many pics as I can to anyone who might be able to help. but so far iam a novice scientific electronic stuff, so go gentle lol.
Attached Images
File Type: jpg IMG_0363.jpg (602.4 KB, 278 views)
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Old 16th September 2013, 05:54 PM   #2368
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first you need to get som other heatsinks. horisontal fins is a very bad idea for a amp like this
whats the rail voltage and bias? is it with or without diodes. if you have diodes, how are they mounted?
and how many output pairs?
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Old 16th September 2013, 06:39 PM   #2369
gabsta is offline gabsta  United Kingdom
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ok so firstly a question I can answer straight away. the heat sinks are fine. they dissipate the heat with no trouble what so ever. I remember asking about that and he said not even at top bias advised for those chips it was cool enough. but I think he reduced the bias.
I need to ask him bout voltage on rails and other stuff as have only just received it back from him. he did build an ordinary f5 which had no trouble but this f5 pushed things a little too far I think as didn't even get to connecting the b1 or the db meters or any of that side of it I think he was using and testing the amp only. and so my suspicion is that it is to do with the wiring inside or the type of wire used or its proximity to the transformer or anything really. as he did say he believes the amp is oscillating and so If I could get an oscilloscope I might find out more.

I have added some more pics of the inside. as far as I know its only one mosfets and diodes burnt out this time last time was the same but only one channel iam not sure this time if more is damaged or if its just same as first time.IMG_0365.jpg

IMG_0367.jpg

IMG_0368.jpg

IMG_0369.jpg

IMG_0370.jpg
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Old 16th September 2013, 08:51 PM   #2370
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what i see here is that the diodes is mounted on the main sink. wich runs so hot that he needed to take the bias down?? the diodes start to conduct earlier when they run hot. so a bias runaway is one possibility. that will blow outputs and set them on fire.
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