Noise measurement on output - how to ?
Dear All,
I took some finished but not properly working F5T out of (temporary) storage to avoit it turning into permananent storage as it bothered me to have that amount of money/time sleeping on the shelves in the workshop.
With the help of forum-member Vix I debugged it to that point that it's definitely usable (I had wrongly connected my ground breakers, i.e. inverting the +/- of the bridge with reference to the NP schematics). Being dual mono in one enclosure added some complexity as well... Vix saved me again.
After testing on the cheap workshop driver I attached a Scanspeak F10 fullrage (90dB sensitivity) to it and I can still hear a faint 50Hz residual (I "think" it's 100Hz) - when I say faint I mean "faint".
Attaching my trusty Fluke 79 III to the output I measure 0.1 mV AC.... with open probes the values are around 300 mV AC all over the place.
Turning on the amplifier the Fluke measures around 2mV AC and gradually goes down to 0.4mV AC (say 20 seconds) then it takes another 20 seconds for the Fluke to show the above mentionned 0.1mV AC.
Is this the right way to measure the residual noise ?
I also do have a digital scope but would suspect it does not any better than the Fluke at those frequencies.
Any hint ?
Thanks in advance,
Max
Dear All,
I took some finished but not properly working F5T out of (temporary) storage to avoit it turning into permananent storage as it bothered me to have that amount of money/time sleeping on the shelves in the workshop.
With the help of forum-member Vix I debugged it to that point that it's definitely usable (I had wrongly connected my ground breakers, i.e. inverting the +/- of the bridge with reference to the NP schematics). Being dual mono in one enclosure added some complexity as well... Vix saved me again.
After testing on the cheap workshop driver I attached a Scanspeak F10 fullrage (90dB sensitivity) to it and I can still hear a faint 50Hz residual (I "think" it's 100Hz) - when I say faint I mean "faint".
Attaching my trusty Fluke 79 III to the output I measure 0.1 mV AC.... with open probes the values are around 300 mV AC all over the place.
Turning on the amplifier the Fluke measures around 2mV AC and gradually goes down to 0.4mV AC (say 20 seconds) then it takes another 20 seconds for the Fluke to show the above mentionned 0.1mV AC.
Is this the right way to measure the residual noise ?
I also do have a digital scope but would suspect it does not any better than the Fluke at those frequencies.
Any hint ?
Thanks in advance,
Max
Using Two transformers
Just after a little help please with transformers.
I've two 300VA, 2x24V physically separate transformers (T1 and T2) that I would like to using in a F5T build. Is it possible to wire them like this...
Parallelising their secondaries, each transformer providing one half of the symmetric supply.
T1's parallelised secondaries then connect to AC1B and AC1A on the DIYAUDIO PSU PCB. Whilst T2's parallelised secondaries then connect to AC2B and AC2A on the same DIYAUDIO PSU PCB.
Is this configuration safe and doable?
Thanks.
Just after a little help please with transformers.
I've two 300VA, 2x24V physically separate transformers (T1 and T2) that I would like to using in a F5T build. Is it possible to wire them like this...
An externally hosted image should be here but it was not working when we last tested it.
Scan by Garf Arf, on Flickr
Parallelising their secondaries, each transformer providing one half of the symmetric supply.
T1's parallelised secondaries then connect to AC1B and AC1A on the DIYAUDIO PSU PCB. Whilst T2's parallelised secondaries then connect to AC2B and AC2A on the same DIYAUDIO PSU PCB.
Is this configuration safe and doable?
Thanks.
Normally it can be done. The manufacturer of the transformer will write in the data sheet if the secondaries can paralleled. Like Talema does here:
https://www.nuvotem.com/products/datasheets/Open-Style-230V-Primary-0300VA.pdf
https://www.nuvotem.com/products/datasheets/Open-Style-230V-Primary-0300VA.pdf
Noob here. Anyone have any advice on where and how to buy the 4 bipolars and 16 matched MOSFETS for a F5T V3 monoblock pair? i already purchased a matched quad JFETS from the store. I read that matching bipolars is not critical. I know next to nothing about transistors, except that i can't get the ones that are listed on the BOM.
As another noob... there are a few options. BTW - I did not do monoblocks and did the "standard" F5V3.
1) You can get them from the store - They have F5 Kits in stock. If you have not sourced your parts yet, that would be my best recommendation. The prices are very reasonable, you're guaranteed to get all the right parts with no confusion, and the matching is done for you.
There is also this person just a few posts back... I think I saw a second post, and it may be worth inquiring if there are more to be had.
Matched IRFP240 + IRFP9240 MOSFETs + F5 Turbo Kits
2) Many places keep them. There is some debate that's way over my head re: whether Vishay's are suitable to the task. Ask around the build thread if that's the route you choose. If you buy a sleeve of 25, you're pretty much guaranteed to get enough matches for your build, plus have enough extras for some other builds. I was a bit apprehensive about matching at first, and it took a while, but it was worth it. I'd give this option a distant second if you're not feeling up to it.
Good luck, and happy building!
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I built my F5V3 monoblocks with separate power supplies. I was just listening to them when I read this, so I took a photo. I got my chassis from ebay, 150mm x400mmx50mm heatsinks with a 10mm base. I am running 46volt supply rails and 2.1 amps total current with CLC supply filtering and 800va transformers. The heatsinks run in the 45-50c range depending on room temp. The first C and L are in the power supply box and there is a DIY Store ps board for the 2nd C filtering in the main amp box.
They sound great, best amp I have owned. I used Jensen input transformers and am driving them balanced with a BBA3 preamp. DAC is a DDDAC 1794.
With a 46v supply I get about 120w continuous into 8 ohms. Current output is excellent with just over 400w into 2 ohms. I did not install the diodes across the source resistors.
The F5V3 is a difficult build and there are lots of chances for errors and short circuits etc. Take your time with the build and double check everything. The bias and offset adjustment takes patience, but once done is stable. Mine have been in service for almost 3 years with no issues.
Here is a link back to where I was building the monoblocks. I built th PS chassis by hand which was a lot of work.
F5 Turbo Builders Thread
F5 Turbo Builders Thread
Bfpca, really excellent work! I don't have precision machining tools to build a metal chassis by hand and have it look professional. I have actually built some of my earlier project chassis by hand and it looks like a hack job, even though most of them work very well. I want this one to look professional so I will support the site and purchase from the store. Your build is really inspiring me to take my time and make sure every step is carefully thought out and executed.
I went for the one transformer layout in the end. Thanks for the advice.
Just running up the bias. Each side sat at 300mV across the 1R resistors.
2019-11-22_07-45-10 by Garf Arf, on Flickr
Just running up the bias. Each side sat at 300mV across the 1R resistors.
2019-11-22_07-45-10 by Garf Arf, on Flickr
It may be early on yet, but once you decide what configuration you'll build, it could be as simple one of a few things:
1) If you've purchased the back panel kits from the store, which I highly recommend BTW, then you can just swap out one of the RCA inputs for an XLR on each case, wire accordingly, and off you go. Neutrik (and other brands of) XLR jacks are easy to source. I don't think I used these exact ones, but here's an example that will fit right into the pre-drilled holes.
Neutrik NC3FPP Chassis Mount Female XLR Connector Plastic "D"
2) If you're handy with a stepped drill bit and a regular bit, keep the existing holes for the RCA inputs and add another one for the XLR.
Again, you'll need to make a few decisions between now and then, but don't let the "as-shippped" case configuration hold you back. Two 5U Deluxe chassis will open up a lot of options for you, both for this project and in the future, if you decide to build more toys and use the same chassis.
Have fun.
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I do have the back panel kit. Definitely quality parts. I think what i am going to do is draw up what i want in CAD and order it from Modhouse directly. What i am looking for is just a slight modification of the standard DIY Audio config. If i ever decide to build a new amp with the same chassis i will probably just order a new back plate from Modhouse with a new config.
F5 Kit here?
I exchanged a note with Nelson, asking him about the F5 kit and if an entire kit- boards, PSU, Chassis, all parts including transistors, resistors, caps etc is avail on this site thru the store. I think the current version is version 3.
He suggested posting my question here.
Can anyone let me know and point me towards the right area to order it if it is?
I'm assuming the build guide is also available?
thanks
I exchanged a note with Nelson, asking him about the F5 kit and if an entire kit- boards, PSU, Chassis, all parts including transistors, resistors, caps etc is avail on this site thru the store. I think the current version is version 3.
He suggested posting my question here.
Can anyone let me know and point me towards the right area to order it if it is?
I'm assuming the build guide is also available?
thanks
@acowans - there is no "single click" full kit from the diyAudio store. However, there are a number of people that can help you out. There is a build guide, but it is not a step-by-step instruction set.
Have you build any of the First Watt designs before? Have you done any other DIY amps?
Have you build any of the First Watt designs before? Have you done any other DIY amps?
Hi
Itsallinmyhead
I just finished the Amp Camp Amp and it works fine,. The build instructions were detailed and therefore the build went fine.
I'd probably want/need similar instuctions for the F5 as my ability to read and solely rely on schematics is limited.
Are there good build instructions for the F5 and a complete parts list that I can use to source the parts ?
thanks
Itsallinmyhead
I just finished the Amp Camp Amp and it works fine,. The build instructions were detailed and therefore the build went fine.
I'd probably want/need similar instuctions for the F5 as my ability to read and solely rely on schematics is limited.
Are there good build instructions for the F5 and a complete parts list that I can use to source the parts ?
thanks