Minimal parts Circlotron

[stoneku]

50W/8R Circlotron Power Amplifer

Each channel need active parts:
* OPA2604 x1
* PowerJFET LU1014D x2

passive parts:
* Resistor x12
* Capacitor x3
* Inductor x1 or x2

Power supply:
* ±24V-DC voltage-gain-stage power x1
* 24V-DC circlotron power stage power x2

 

[latala]

Just what i have been looking for any figures on this?
Trev

 

[jacques antoine]

Where do you source LU1014D ?

 

[llwhtt]

Looks very similar to a SUMO NINE.

Craig

 

[stoneku]

Hi...

@jacques antoine, about PowerJFET, you can found in eBay & Taobao, not just LU1014D pls try LD1014D & LD1010D all are similar spec. 24V 50A 80w , they are used in PC motherboard switching power regulator, very cheap.

@llwhtt , yes , it is clone the SUMO NINE with variation, more simple with same power, max will be 70w/8R .

 

[stoneku]

A modify of this OPamp PowerJFET Circlotron, still simple , The PowerJFET is tiny size body only about 6mm*6mm .
1. Cascode PowerJFET
2. Adding positive-input feedback

 

[alexberg]

Do you have any idea what is the voltage across the output transistor?

 

[stoneku]

@alexberg
voltage across the output transistor ? I dont understand what you mean.

 

[as_audio]

drain to source voltage of the inner transistors ..

Do you show simulations only or have an actual build ?

 

[Boden]

Isn't there any reliable source (Digikey, Mouser, Conrad or so) for these LU/LD power Fets? Sorry but both eBay and Taobao are a recipe for disaster and fake components.

 

[stoneku]

@alexberg, @as_audio ,
Woo, both of your concern are right , simulation the Voltage of T1 & T2 will be maxmum almost 48V, so may need cascode high-voltage MOSFET .

 

[as_audio]

I think the suspicion was in fact that voltage on inner transistors in cascode is unduly low.

 

[stoneku]

@Boden ,
This PC-motherboard used PowerJFET are not audio famous parts, not worth to fake it. My information the manufacture LOVOLTECH semicoduct company is close about 2014, LU1014D stop manufacture about 2008, so in market only a few stock parts . If you want to produce official product dont think about this, but I just for hobby and learning . In Taobao I buying LD1010D 100x parts amout is less then mailing charge.

 

[stoneku]

Modify: use same PowerJFET for cascode , distortion more high a little.

 

[stoneku]

Modify V4: Cascode IRFP150 100V 41A, bias LED x3 , fix JFET V-ds . Not original simple structure 😡

 

[as_audio]

We would love to see real measurements ..

 

[Ryssen]

Have you built this amp and listened to it?

 

[xrk971]

I made a SE Class A headphone amp with LU1014D’s and they sound quite nice. They are so small though. I am not sure the best format for putting a lot of power through them as a speaker amp with 50w output.

 

[alexberg]

@alexberg, @as_audio ,
Woo, both of your concern are right , simulation the Voltage of T1 & T2 will be maxmum almost 48V, so may need cascode high-voltage MOSFET .

Duh...

 

[EUVL]

You might find some useful information about how to get the best from a LU1014 in Nelson Pass' 2 excellent articles :
Zen Variations 8 | Pass DIY
Zen Variations 9 | Pass DIY
Especially how to use cascode to form a triode cell with much improved linearity.

And if you really want to build a circlotron with minimum parts, maybe take a look at this :
The New-Tron
F5 Listening Impressions & Discussion

(Quasi)complementary JFET power amplfier
Downscaling Zen v.9 for use as headamp


Cheers,
Patrick