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Old 9th June 2020, 09:36 AM   #6091
JeffYoung is online now JeffYoung  Ireland
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F5 Turbo Builders Thread
How does your music get to the F5? If it starts off as digital files through something like Roon, it's often easiest to use Roon's DSP engine to do balancing as well as correcting room nodes.

I'm sure Audirvana has something similar; not sure about others.
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Old 9th June 2020, 10:09 AM   #6092
Bfpca is offline Bfpca  Canada
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F5 Turbo Builders Thread
Keep in mind that some recordings, particularly those from the early stereo era have some issues with balance, often featuring instruments skewed totally to one side. Depending on the song this can lead to the entire perspective of the performance shifting off centre.
I have experienced this slight imbalance in channels over the years. There have been good suggestions made about room acoustics and front end equipment issues. Sometimes, in my case, the problem is with my ears. I sometimes have problems with allergies and this leads to my hearing being impacted more in one ear than the other. It has been happening lately due to the very high levels of tree pollen in the air at this time of year.
With regards to room acoustics, if you have asymmetrical room reflections in the high frequencies this can cause the treble to pull to one side. You could experiment with speaker toe in and maybe some room treatment, perhaps as simple as a wall hanging to break up a large expanse of reflective wall area.
You could simply try to compensate with a balance adjustment.
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Old 9th June 2020, 10:21 AM   #6093
wijgers is offline wijgers  Netherlands
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Quote:
Originally Posted by Bfpca View Post
Keep in mind that some recordings, particularly those from the early stereo era have some issues with balance, often featuring instruments skewed totally to one side. Depending on the song this can lead to the entire perspective of the performance shifting off centre.
I have experienced this slight imbalance in channels over the years. There have been good suggestions made about room acoustics and front end equipment issues. Sometimes, in my case, the problem is with my ears. I sometimes have problems with allergies and this leads to my hearing being impacted more in one ear than the other. It has been happening lately due to the very high levels of tree pollen in the air at this time of year.
With regards to room acoustics, if you have asymmetrical room reflections in the high frequencies this can cause the treble to pull to one side. You could experiment with speaker toe in and maybe some room treatment, perhaps as simple as a wall hanging to break up a large expanse of reflective wall area.
You could simply try to compensate with a balance adjustment.
some tracks are from the early era indeed. there is more than just my F5!

Quote:
Originally Posted by JeffYoung View Post
How does your music get to the F5? If it starts off as digital files through something like Roon, it's often easiest to use Roon's DSP engine to do balancing as well as correcting room nodes.

I'm sure Audirvana has something similar; not sure about others.
I'm using the Camridge Audio Azure 851N as Digital pre-amp and streamer. So yes I can play with balance as you mentioned.

But I will try to figure out if the amp is OK.
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Old 9th June 2020, 02:35 PM   #6094
nashbap is offline nashbap  United States
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F5 Turbo Builders Thread
Nils,

In addition to what has been suggested earlier check that you have not inadvertently swapped the + and - connections at the amp and at the speakers.

Nash
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F5TV3, AVC, BA3b pre, Salas DCG3b, OBL-15, SonyVfet2pair monos
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Old 1st July 2020, 08:35 PM   #6095
Shteve is offline Shteve
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I bought a pair of F5 Turbo V2 boards and silicon about 6 years ago on a sleep deprived new father hood, uneducated whim. I slowly bought components and heat sinks and have designed what will be (one day) a pair of mono blocks. I've subsequently had some sleep, read what a wonderful chap Nelson is and built the B1 Korg with much success. Thank you very much to all for the wonderful documentation this site gives.

But I have made a mistaken purchase. The transformers are 500VA 230 primary to dual 25V secondary. Mains is measured at 240+V round our way so I think I should expect to see ~36V at the rails. The V2 aims for 32V rails and I'm worried that the extra 4V will be to much for the input JFETs.

What do you think. Risk it with heat sinks on the JFETs or cascade as suggested for V3.

If cascading, can anyone help me understand what value R25/R27 and R26/R28 voltage dividers should be to get the correct (32V?) at the JFETs please?

And is 32V the 'optimal' voltage for the JFETs, or should I target something else, and why?

No hurry, I haven't built up the PSU yet and the boxes are only just drilled and ready for paint and oil. Still very much in the shed and not ready for the kitchen table yet.

Best regards
Steve
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Old 1st July 2020, 09:22 PM   #6096
AudioSan is offline AudioSan  Norway
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cascode them. Let the J-fets se about 16V.
Formula for calculating the cascode voltage is: railvoltage/(R25+R27)*R27.
so for 36Vdc rails you can use 10Kohm for R25/R26 and also 10Kohm for R27/R28.
that will be 36Vdc/(10+10)*10=18Vdc
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Old 2nd July 2020, 07:34 PM   #6097
Shteve is offline Shteve
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Thank you. Best I go paint the box and order some parts.
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