I'm using 0.25, but most of my other values also came out different when I simulated it. I'm also running 2x of the double die devices, so mine is quite a bit different.
As before, @mikelm would request not to post full schematics on the thread, regardless of accuracy. That's asking for cloners to start looking.
As before, @mikelm would request not to post full schematics on the thread, regardless of accuracy. That's asking for cloners to start looking.
Thought I might try Powertrons for current sense which Mouser don't stock but they seem to be good value for most other things
Sangram, sorry about the diagram, I had forgotten about this policy. Please remove if required.
May ask if you had any stability issues with the double die laterals ? I was thinking to use them too but a friend who used them in a MOFO amp recently got oscillation in the 100s of meg Hz region even with generously valued gate stoppers in place
Did your F7 version work OK without gate stoppers ( or other resonance damping measures ? )
thanks
May ask if you had any stability issues with the double die laterals ? I was thinking to use them too but a friend who used them in a MOFO amp recently got oscillation in the 100s of meg Hz region even with generously valued gate stoppers in place
Did your F7 version work OK without gate stoppers ( or other resonance damping measures ? )
thanks
Re the removal, best to report your own post for the team to take action. We don't work alone. And it was a request as no one is actively enforcing the policy. It's just to protect the circuit from cloners.
Re the double die devices I've not seen any major issues, though some fine-tuning is still needed in sims. They need stoppers and a bit more mollycoddling than the Renesas devices, that's for sure (I have some zobels in place, hopefully won't need them). There are also 4 dies effectively, so the input stage is quite heavily loaded. To help with this, I also use a cascode. The resistor values I have are markedly different from the ones you've shown, so I tend to have more feedback in general.
I have yet to fire it up due to some pending metalwork, but hope to do so next week.
Re the double die devices I've not seen any major issues, though some fine-tuning is still needed in sims. They need stoppers and a bit more mollycoddling than the Renesas devices, that's for sure (I have some zobels in place, hopefully won't need them). There are also 4 dies effectively, so the input stage is quite heavily loaded. To help with this, I also use a cascode. The resistor values I have are markedly different from the ones you've shown, so I tend to have more feedback in general.
I have yet to fire it up due to some pending metalwork, but hope to do so next week.
Manganin has two advantageous characteristics:
* It has a very low temperature co-efficient
* It is non magnetic.
I have some bare manganin wire which I use for low power applications - I have not yet heard a resistor that sounds better
I did not know that powertron used it - thanks for sharing
* It has a very low temperature co-efficient
* It is non magnetic.
I have some bare manganin wire which I use for low power applications - I have not yet heard a resistor that sounds better
I did not know that powertron used it - thanks for sharing
Yes, the bulk foil resistors TO-218/TO-247 size Powertron (now part of VPG, Vishay) precision devices use the Isabellehutte Manganin foil (their other well-known alloy is the Isotan/Constantan (Cu55%, Ni45%, Mn1%) foil - a much brighter sound and has been around for many years.
I use them as source resistors, etc and they don't seem to mind getting a 'bit hot' (the temp drift is minimal up to about 60*C) - the wire wound ones like the 'General Resistance' resistors (there's a diyA group buy) need to stay cool.
There's quite a few surface mount units but generally unavailable in small quantities for casual diy purchase although Rhopoint are pretty accommodating - the Caddock MP9000 (the same TO-247 size) are similar but metal film - good resistors too
Surprisingly, the Mn wire is still around on eBay, not sure about delivery these days
I use them as source resistors, etc and they don't seem to mind getting a 'bit hot' (the temp drift is minimal up to about 60*C) - the wire wound ones like the 'General Resistance' resistors (there's a diyA group buy) need to stay cool.
There's quite a few surface mount units but generally unavailable in small quantities for casual diy purchase although Rhopoint are pretty accommodating - the Caddock MP9000 (the same TO-247 size) are similar but metal film - good resistors too
Surprisingly, the Mn wire is still around on eBay, not sure about delivery these days
jameshillj
Oh is Manganin supposed to be scarce these days ?
There is a supplier close to where I live and they still have plenty in stock - but that is not much use to you I guess
For those is UK it is here: https://www.wires.co.uk/
Oh is Manganin supposed to be scarce these days ?
Sorry Mike, Not really, but the extremely close tolerance thru-hole devices have become specialty products hence the fancy prices at places like the HiFi Collective, etc - the equivalent Mundorf versions are even more expensive - the curious thing is that the SMD equivalents are a lot cheaper if you can get them.
Who makes the Manganin wire for "wires.co.uk"? There's quite an array of Manganin content wire like 6j6, 6j11, 6j12, etc made in China with different alloy content and manufacturing process - it's not really "Manganin Alloy" at all but unsure what differences this would make to the "sound" of the wire.
Sorry Mike, Not really, but the extremely close tolerance thru-hole devices have become specialty products hence the fancy prices at places like the HiFi Collective, etc - the equivalent Mundorf versions are even more expensive - the curious thing is that the SMD equivalents are a lot cheaper if you can get them.
Who makes the Manganin wire for "wires.co.uk"? There's quite an array of Manganin content wire like 6j6, 6j11, 6j12, etc made in China with different alloy content and manufacturing process - it's not really "Manganin Alloy" at all but unsure what differences this would make to the "sound" of the wire.
Using matched Jfets in the F7
I am thinking that if we have very well matched Jfets on the input of the F7 might there be a little too much cancelation of 2nd harmonic distortion ?
If we are not using source degen resistors to get a little bit of asymmetry, might it not be better subjectively to have slightly unmatched Jfets ?
Would be interested to hear hear from anyone who has built with matched Jfets and subsequently measured the FFT.
thanks
mike
I am thinking that if we have very well matched Jfets on the input of the F7 might there be a little too much cancelation of 2nd harmonic distortion ?
If we are not using source degen resistors to get a little bit of asymmetry, might it not be better subjectively to have slightly unmatched Jfets ?
Would be interested to hear hear from anyone who has built with matched Jfets and subsequently measured the FFT.
thanks
mike
Yes, my clone shows relatively high intermodulation products with 100 Hz from the rectifier. However, they are about 10 dB below the H3 level (see my plot at #1779). Better smoothing in the power supply would be an option here.
Duplicate Exicons might help for better linearity, but would result in the F7 turbo. However, we want to clone an F7 classic.
Duplicate Exicons might help for better linearity, but would result in the F7 turbo. However, we want to clone an F7 classic.