From Elvee himself: If a volume pot is placed directly in front of the amplifier, its value should be 4.7K or less.
I tried using 250K (knowing it wouldn't work) and the result was horrible.
Did you try 250K pot with Piersma's inverted Circlophone? Since this particular design incorporates an additional jfet front-end, input impedance should be much higher than standard Circlophone. Thus, such higher value pots (at least as much as 100K) should be viable on that design in my opinion. Elvee's 4k7 pot recommendation is peculiar to standard Circlophone (if you're not using an external buffer of course).
My Impressions
Hallo to Elvee, Terranigma all Others.
I have build up one Mosfet- Circlo Terranigma Board with given
Components, Servo is 2905A here, only for testing that simple Circuit.
So i put a PSU 2x 10 000µF per Rail, on Input i used a 100k Pot without
any Problems and a Solen Fast PP 4,7µF couple- Cap.
It surprised me very much how nice that little Wonder sounds.
Now its time to say: Thank you Elvee, terrenigma, piersma .... all other
Mentors and rebuilder this Amp for given Instruction.
The first build impressed me, now i build a Darlington- Variant, its running
on TV in moment.
Here i have done some Changes.
1. input Cap is Mundorf M-Cap 4,7µ+ parr. 0,010µ(10n) orange Drop 715P-
my Favorit, also in Tube Amp.
If any can do or would, should do it, its not expensive, but give much more sound impression- my opinion.
2. now input LTP is BC337- don't know exactly who much better, but i have
read about lower Rbb (Rdd)?- 30 Ohm has influence in Sound?- so i test it.
3. I have found good sourced 2N4033 PNP 1A 150Mhz- it's not a Foult- doing
good job here.
In this test are used simple mono 2x 50k Pot.
All in all it sounds clear, detailed in staging, imaging is pleasing.
It don't need much extravagances to sound nicely, only good sorted parts, i
think.
Some shoots, about my experience.
The third with terranigma boards shout also be a Mosfet.
One Question: I have 2SK399 Hitachi, can i also use there here?
Next i will build up a CFP with terra- boards to listen the different.
Warm Regards Bangla H.
Hallo to Elvee, Terranigma all Others.
I have build up one Mosfet- Circlo Terranigma Board with given
Components, Servo is 2905A here, only for testing that simple Circuit.
So i put a PSU 2x 10 000µF per Rail, on Input i used a 100k Pot without
any Problems and a Solen Fast PP 4,7µF couple- Cap.
It surprised me very much how nice that little Wonder sounds.
Now its time to say: Thank you Elvee, terrenigma, piersma .... all other
Mentors and rebuilder this Amp for given Instruction.
The first build impressed me, now i build a Darlington- Variant, its running
on TV in moment.
Here i have done some Changes.
1. input Cap is Mundorf M-Cap 4,7µ+ parr. 0,010µ(10n) orange Drop 715P-
my Favorit, also in Tube Amp.
If any can do or would, should do it, its not expensive, but give much more sound impression- my opinion.
2. now input LTP is BC337- don't know exactly who much better, but i have
read about lower Rbb (Rdd)?- 30 Ohm has influence in Sound?- so i test it.
3. I have found good sourced 2N4033 PNP 1A 150Mhz- it's not a Foult- doing
good job here.
In this test are used simple mono 2x 50k Pot.
All in all it sounds clear, detailed in staging, imaging is pleasing.
It don't need much extravagances to sound nicely, only good sorted parts, i
think.
Some shoots, about my experience.
The third with terranigma boards shout also be a Mosfet.
One Question: I have 2SK399 Hitachi, can i also use there here?
Next i will build up a CFP with terra- boards to listen the different.
Warm Regards Bangla H.
Attachments
Congratulations Bangla! Nice to see someone else also noticed my mini boards. If you supply the mosfet (Vertical Mosfet, Hexfet) version with right voltage and use right components accordingly, you can extract 100-150 watts class-A sound easily from these small beasts depending on your choice of output mosfets. I suggest you to use at least 30V supplies with mosfet version due to loss of 4-5V to turn on mosfets. But 25V is also ok. Another thing is, if you aren't using a buffer, I suggest you to use lower value pots (like 4K7 and 10K). You may notice the difference.
For CFP, bear in mind that this particular version of Circlophone is somekind of a different animal and has built by very few people (including me). It sounds very well with current compensation values but it has some overshoot issue with square wave. With normal listening sessions, this issue shouldn't appear as a big problem but you must be aware of this before starting to build it in my opinion. You can simulate some other compensation strategy if you want.
Thank you for sharing photos. Keep up good work and update us for further progress.
PS: About 2SK399; I checked its datasheet and it seems a suitable one.It's high capacitance values and leg arrangement (GDS) suggest that this one is a Vertical type mosfet and suitable for Circlophone. There are also Lateral mosfets from Hitachi but their leg arrangement is different and require extra transistors to drive.
For CFP, bear in mind that this particular version of Circlophone is somekind of a different animal and has built by very few people (including me). It sounds very well with current compensation values but it has some overshoot issue with square wave. With normal listening sessions, this issue shouldn't appear as a big problem but you must be aware of this before starting to build it in my opinion. You can simulate some other compensation strategy if you want.
Thank you for sharing photos. Keep up good work and update us for further progress.
PS: About 2SK399; I checked its datasheet and it seems a suitable one.It's high capacitance values and leg arrangement (GDS) suggest that this one is a Vertical type mosfet and suitable for Circlophone. There are also Lateral mosfets from Hitachi but their leg arrangement is different and require extra transistors to drive.
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I forgot to meantion that CFP version doesn't require lower value pots as standard front-end does (if you don't have relatively high impedance source of course).
2N4033 is a good find but its 20pF Cob is slightly higher than my sweet spot (8-12 pF).
2N4033 is a good find but its 20pF Cob is slightly higher than my sweet spot (8-12 pF).
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This vertical FET output stage looks interesting. Can you please point to schematic and PCB?
I have posted it builders thread but I should post it to this thread instead:
MOSFET & Darlington Version
Schematic is at post#16
Thanks for that. Your board is very compact - seems simpler than the base Elvee design. It still has sliding bias controlled by servo and virtual class A operation?
Of course, otherwise it won't be a Circlophone. It is actually same design but there is no need to driver transistors (BD139/140) in Vertical mosfet & Darlington version. Other thing is, if you look carefully, active components are inverted (different polarity) and supply voltage is also inverted. This is a must to use NPN power darlington/mosfet at outputs. If you have PNP output devices and want to use as output, you can follow the standard scheme by inverting power supplies and bypass capacitors accordingly (haven't built & tested). Circlophone is a very flexible design.
If you interest with mosfet version, I suggest you to use matched output devices. There are sellers in ebay (search: matched irfp240) with reasonable prices.
In my opinion, mosfet variations of Circlophone (including Piersma's) one of the the best mosfet designs (if not the best) available in forum. Most vertical mosfet designs are using complementary parts (pnp+npn together) so due to production dispersion between pnp and npn mosfets, this aspect cause imbalance in symmetrical operation. Since Circlophone uses same polarity devices from start to end, it is prone of such handicaps, especially in mosfet versions.
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I have Piersma's inverted JFET input Circlophone but it uses a BJT for output not a MOSFET. I like designs that use same sex vertical MOSFETs very much. The Pass Circlotron uses same sex n channel MOSFETs as well but is differential input and a true class A heater. The Circlotron manages to be class A without being a room heater so very cool, literally. 🙂
Thanks for the explanation.
Thanks for the explanation.
use lower value pots (like 4K7 and 10K). You may notice the difference.
Hallo terranigma.
Thank you very much for given new input, new orientation.
I have read many details in thread here, also daniel gives very good information to find good parts.
The next MosFet- Circlo with better Vishay RN60 Resistors should be with 35VDC on Rails and also i lower the Pot impedance to 10k, pledged!
Your little compact Board and not needed Driver was the mainreason to build
"The MosFet Circlo".
I have bought the IRFP250M (5.generation of vertical Fet) in Mouser shop a
batch of 25 and all are in same Vgs, so lucky about this.
So i started with Boards ACA from diy Audio store build a pair using these
Mosfets.
So xrk971 if you can use these M-Type, they have impressed me very much
with clear sounding.
Now, where i now how good they work i must find a other good Amp to use.
The idefixes- Marc Nmos200 has to much Power in my usage.
Terranigma that is the reason why i use lower Railvoltage, but i taste out higher.
In the first Circlo-Mos are 2N2905A, work fine.
With my lazy ears i couldn't realise any missing in use 2N4033 in second build.
I am not a expert with measuring equipment only can trust what i listen.
Of course is the next step put the Amp together with the right Speaker.
For examble the ACA work together with my Fostex FE126 Horns very well.
For CFP, bear in mind that this particular version of Circlophone is somekind of a different animal and has built by very few people (including me). It sounds very well with current compensation values but it has some overshoot issue with square wave. With normal listening sessions, this issue shouldn't appear as a big problem but you must be aware of this before starting to build it in my opinion. You can simulate some other compensation strategy if you want.
That makes me bit bad tempered to read that.
Yes i realise there was woke up a different animal, hmmmm..... now i not
what i exactly should do
But the MosFet, Darlindton Variant runs very good, so i'm not real disap-pointed now.
Hopefully there are any experts who can setup the beasty animal CFP in right
working conditions, that we later also can enjoy it.
The overshoot comes from capacitance, thats the own what i not sure know-
really not an expert at that point.
Regards Bangla.
enjoying listening Circlophone now.
Hallo terranigma.
Thank you very much for given new input, new orientation.
I have read many details in thread here, also daniel gives very good information to find good parts.
The next MosFet- Circlo with better Vishay RN60 Resistors should be with 35VDC on Rails and also i lower the Pot impedance to 10k, pledged!
Your little compact Board and not needed Driver was the mainreason to build
"The MosFet Circlo".
I have bought the IRFP250M (5.generation of vertical Fet) in Mouser shop a
batch of 25 and all are in same Vgs, so lucky about this.
So i started with Boards ACA from diy Audio store build a pair using these
Mosfets.
So xrk971 if you can use these M-Type, they have impressed me very much
with clear sounding.
Now, where i now how good they work i must find a other good Amp to use.
The idefixes- Marc Nmos200 has to much Power in my usage.
Terranigma that is the reason why i use lower Railvoltage, but i taste out higher.
In the first Circlo-Mos are 2N2905A, work fine.
With my lazy ears i couldn't realise any missing in use 2N4033 in second build.
I am not a expert with measuring equipment only can trust what i listen.
Of course is the next step put the Amp together with the right Speaker.
For examble the ACA work together with my Fostex FE126 Horns very well.
For CFP, bear in mind that this particular version of Circlophone is somekind of a different animal and has built by very few people (including me). It sounds very well with current compensation values but it has some overshoot issue with square wave. With normal listening sessions, this issue shouldn't appear as a big problem but you must be aware of this before starting to build it in my opinion. You can simulate some other compensation strategy if you want.
That makes me bit bad tempered to read that.
Yes i realise there was woke up a different animal, hmmmm..... now i not
what i exactly should do
But the MosFet, Darlindton Variant runs very good, so i'm not real disap-pointed now.
Hopefully there are any experts who can setup the beasty animal CFP in right
working conditions, that we later also can enjoy it.
The overshoot comes from capacitance, thats the own what i not sure know-
really not an expert at that point.
Regards Bangla.
enjoying listening Circlophone now.
Bangla H,
If you have the complementary IRFP9250 you can build the vHex
http://www.diyaudio.com/forums/solid-state/286992-irfp240-9240-amplifier-simulated-tina-25.html
Or the Apex FH9 which I helped design. The FH9 is basically an FX8 with provision for vertical hexFETs via simple Vbe multiplier and source/drain resistors. Here is nice layout by Sonal Kunal. FH9 is an easy build and sounds very nice - almost on par with Circlophone.
Schematic here:
http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-733.html#post4702737
If you have the complementary IRFP9250 you can build the vHex
http://www.diyaudio.com/forums/solid-state/286992-irfp240-9240-amplifier-simulated-tina-25.html
Or the Apex FH9 which I helped design. The FH9 is basically an FX8 with provision for vertical hexFETs via simple Vbe multiplier and source/drain resistors. Here is nice layout by Sonal Kunal. FH9 is an easy build and sounds very nice - almost on par with Circlophone.
Schematic here:
http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-733.html#post4702737
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Hi Bangla,
I'm not an expert either. I'm just sharing my early experiences those based on my limited capabilities. Since I have decided to build a B1 like external buffer to use with standard Circlophone front-end (what it is like darlington&mosfet pcb), I didn't pay enough attention to CFP like alternative front-ends to run simulations in order to find an alternative compensation scheme. Maybe a bit later.
I'm using very standard Circlophone by now with a 10K pot and this setup fair enough to my ears..so I became a bit lazy about building DC coupled B1 buffer unfortunately. I couldn't finish my DAC project yet thus I need to give priority for that instead of buffer and other things by now.
Regards.
Hallo terranigma.
In that mind i find it is a nice place, sharing hobby- without pirates- hopefully.
Yesterday i have turned and soldered wires with 10k pot for input.
Today morning i hooked it up for short listening.
It harms very much better in overall sounding like promised.
Now i realized my fault.
Before there was some buckling in any frequencies, i could listen with my sharp ears,
but after changing i understand.
And i have unfinished mezmerize shunt B1, it's time to do now, for given reason!
So Solder iron on go away.
Regards Bangla.
Or the Apex FH9 which I helped design.
Hallo xrk971.
Congrats, very nice designed Amp.
Could i say you drives me crazy?
In that threat i read also time to time, many good people and stuff sharing.
And Apex is a wide range of possibilities- AX6, 11, NX14 and also these one.
Last days i am inspired by Borys FET- Hex Amp VSSA- inspired. He used better
pairing 240/9140, which i have pairs on Hand.
Also simpler shaan picibi variant is very interesting- LatMos- Amp.
Jason Kuetemann TO-3 Variant, he wrote: "blowing my mind"
For moment i have saved the pic to remind back later.
How find time to etch, soldering so many😕. Also it is a Question of budget i have.
Is there any reason to cry now?😀😱
Looking forward: The MosFet/Darlington is closed in Heart.
Regards Bangla.
Hallo xrk971.
Congrats, very nice designed Amp.
Could i say you drives me crazy?
In that threat i read also time to time, many good people and stuff sharing.
And Apex is a wide range of possibilities- AX6, 11, NX14 and also these one.
Last days i am inspired by Borys FET- Hex Amp VSSA- inspired. He used better
pairing 240/9140, which i have pairs on Hand.
Also simpler shaan picibi variant is very interesting- LatMos- Amp.
Jason Kuetemann TO-3 Variant, he wrote: "blowing my mind"
For moment i have saved the pic to remind back later.
How find time to etch, soldering so many😕. Also it is a Question of budget i have.
Is there any reason to cry now?😀😱
Looking forward: The MosFet/Darlington is closed in Heart.
Regards Bangla.
Bangla H:
There are certainly more designs than any one person can hope to build in a lifetime around here. 🙂
We are very lucky so many talented designers share their designs and so many people help out with layouts and double checking for errors, etc. once a layout has seen by (probably) thousands of eyes and people agree it's ok to go - I order PCBs from Singapore etc with Gerber files provided by the layout artists. Wait 3 weeks - which is same time for BOM to arrive from Aliexpress. Then build. The soldering is the easy (and fun) part.
I want to make the MOSFET Circlophone or All-FET Circlotron next.
Regarding the FH9 above, we have a confirmed second build by another member and he says it works great with SMPS even. No noise when no input.
Sorry for the OT - now back to Circlophone fun !
There are certainly more designs than any one person can hope to build in a lifetime around here. 🙂
We are very lucky so many talented designers share their designs and so many people help out with layouts and double checking for errors, etc. once a layout has seen by (probably) thousands of eyes and people agree it's ok to go - I order PCBs from Singapore etc with Gerber files provided by the layout artists. Wait 3 weeks - which is same time for BOM to arrive from Aliexpress. Then build. The soldering is the easy (and fun) part.
I want to make the MOSFET Circlophone or All-FET Circlotron next.
Regarding the FH9 above, we have a confirmed second build by another member and he says it works great with SMPS even. No noise when no input.
Sorry for the OT - now back to Circlophone fun !
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Yes, that's why we all have to select, what we can realize with given talent, money and time.
For that i actually enjoy even the ACA, also, with station "cool jazz"- real cool to listen.
I have also done a query to FH9, last minutes.
The Thread 745 sites now- wow!
Enjoy listening music. Bangla.
Nice!!!
I noticed there is a +ve and -ve and signal ground. Is this setup for differential balanced inputs now? Do we need to ground the -ve input if not using balanced input?
Also, are you using MOSFET outputs or BJT's?
I have BJT already and now want to try a vertical MOSFET IRFP240. Or maybe 9240 - still awaiting directions on how to implement MOSFET outputs.