You can pretty much put R100's as a drop in for N ch mosfets, keeping in mind the differences in Vgs values, which are on the order of a volt and a half.
You should expect lower distortion and wider bandwidth without any effort.
Keep in mind that there are some DC gate currents on the order of 10 microamps or so, and you should confirm the value If the source impedance is high.
You should expect lower distortion and wider bandwidth without any effort.
Keep in mind that there are some DC gate currents on the order of 10 microamps or so, and you should confirm the value If the source impedance is high.
well i intend on trying it with jx, but from what i gather some more drive is needed from the input stage when using them. anyone care to offer a solution? is it as simple as paralleling more fuses and using little heatsinks? finding the illusive j109v?
or must we keep jx rather than jjx by using a different device like small mosfet or bipolar (or little linear tech ref) and losing mosfet for r100? these are things i intend to find out, but i also would like to hear from those who have tried it.
or must we keep jx rather than jjx by using a different device like small mosfet or bipolar (or little linear tech ref) and losing mosfet for r100? these are things i intend to find out, but i also would like to hear from those who have tried it.
You can pretty much put R100's as a drop in for N ch mosfets, keeping in mind the differences in Vgs values, which are on the order of a volt and a half.
You should expect lower distortion and wider bandwidth without any effort.
Keep in mind that there are some DC gate currents on the order of 10 microamps or so, and you should confirm the value If the source impedance is high.
Do the SS jfets have a different sonic signature than the mfets. I know there is a different sound, but is this a result of lower distorion or is it a combination of lower distortion and all together different sound. Kind of like different kt88 tubes.
Last edited:
When I get lower distortion out of a part I tend to use it as
an excuse for less feedback, so the net result is often not
less measured distortion.
I like the sound of the Jfets - it's more relaxed and organic
in quality, and of course this reflects my taste. If I listened
to punk or metal, or if I am watching TV or driving the car,
then these things wouldn't be important.
THanks.When I get lower distortion out of a part I tend to use it as
an excuse for less feedback, so the net result is often not
less measured distortion.
I like the sound of the Jfets - it's more relaxed and organic
in quality, and of course this reflects my taste. If I listened
to punk or metal, or if I am watching TV or driving the car,
then these things wouldn't be important.
Needed an good explanation for my wife to buy 6 of them to put in my 3 pair AJ mono blocks. As if they aren't good enough..... I think i may have a problem.
Ah, what a shame. Is anyone aware of any online retailers that can sell relatively small quantities?
I am sure he would love to sell you as few or as many as you are willing to buy. They come matched too.
When I get lower distortion out of a part I tend to use it as
an excuse for less feedback, so the net result is often not
less measured distortion.
I like the sound of the Jfets - it's more relaxed and organic
in quality, and of course this reflects my taste. If I listened
to punk or metal, or if I am watching TV or driving the car,
then these things wouldn't be important.
This makes me want to read the negative feedback article again. Seems like sonic purity is your quest. One last bothersome question if I may. How would you describe the sound of a fet circlotron. Thinking for a while of using SS fets in this unusual schem. Many have built one, but sound is not often spoken of. Perhaps fellow builders have grown wise to the trap of describing ones personal musical experience.
Negative feedback with SS R100 in Circlotron
I use the R100's in a circlotron (2x +28V supplies) with a bit less feedback, and I must say these SS are very stable. I think the need of feedback depends on the speakers you use.
Please do mind that the gain changes with the amount of feedback:
>nfb = <gain
It's important to keep the volume at the same level in comparative listening tests....
My circlotron sounds a bit more laid back (or natural?) than my F5. But bass control is really, really good on my 4 Ohms 94dB 'd appolito system.
And 50W@4Ohm is more than enough
So I can really recommend using the R100's in a circlotron setup, but don't cut corners in the power supplies!
Have fun!
I use the R100's in a circlotron (2x +28V supplies) with a bit less feedback, and I must say these SS are very stable. I think the need of feedback depends on the speakers you use.
Please do mind that the gain changes with the amount of feedback:
>nfb = <gain
It's important to keep the volume at the same level in comparative listening tests....
My circlotron sounds a bit more laid back (or natural?) than my F5. But bass control is really, really good on my 4 Ohms 94dB 'd appolito system.
And 50W@4Ohm is more than enough
So I can really recommend using the R100's in a circlotron setup, but don't cut corners in the power supplies!
Have fun!
Last edited:
I use the R100's in a circlotron (2x +28V supplies) with a bit less feedback, and I must say these SS are very stable. I think the need of feedback depends on the speakers you use.
Please do mind that the gain changes with the amount of feedback:
>nfb = <gain
It's important to keep the volume at the same level in comparative listening tests....
My circlotron sounds a bit more laid back (or natural?) than my F5. Butt bass control is really, really good on my 4 Ohms 94dB 'd appolito system.
And 50W@4Ohm is more than enough
So I can really recommend using the R100's in a circlotron setup, but don't cut corners in the power supply!
Have fun!
Did you use MRothatcher's design?
I've listened to a few variations of SemiSouths
1. BA-1 with 1 output
2. Mini-A with SSR100 output
3. BabelfishJ2
4. F2J
The bottom three sounded the best to me, with 2,4 having a similiar flavor. The Mini-A sounds a bit more 'warm' than the others.
The F2J with no feedback really is really really nice, and the BabelFish J2, can change it's sonic signature playing around with source and gate resistors.
I tried a variation on what the J2 appears to look like, but removed the current limiting and set a pair of R100's on fire!
All of them sound can sound 'cleaner' than the IRFP240 counterparts. As I've stated elsewhere, Whisky for MOSFET, Vodka for R100 JFET.
I think with a circlotron that maybe the R085's could be used?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.