Dynalo parts replacement

[edwtsui]

Hi folks,

As you know that the JFET and BJT of Dynalo are discontinued already, could anyone suggest the replacement?

2SJ109
2SK389
2SC1815
2SA1015

 

[00940]

You can replace the jfet by a quad of 2sk170/2sj74, preferably matched.

The transistors, I've replaced by bc550c/bc560c.

 

[edwtsui]

Thanks. But 2sk170/2sj74 are also discontinued. Any other suggestions??

 

[00940]

Sadly, there's no true alternative to these jfet. It's been discussed here: Replacement For Toshiba 2SK170/2SJ74

Since you're in Hong Kong, there's a reliable seller selling pairs of matched 2sk170/2sj74: FET Audio | Hi-End Audio Projects

 

[thuanth43]

Or, just order new revision of the Dynalo. All current production parts, without the hassle of those discontinued and expensive parts.

 

[cspirou]

I recently made a Dynalo Mk2 with that340 jfets for the input. At headamp they recently released the Gilmore Lite Mk2 which is similar to the Dynalo. I wonder what he is using for jfet inputs?

I would probably just do a Krell KSA Clone

 

[edwtsui]

Or, just order new revision of the Dynalo. All current production parts, without the hassle of those discontinued and expensive parts.

Any schematic for the new version Dynalo??

 

[cspirou]

Here you go

 

[edwtsui]

Thanks. So it is a balanced input? Can it be unbalanced??

 

[cspirou]

Yes, just ground the negative input for unbalanced input

 

[00940]

The that 340 is made of BJT, not jfet. The new dynalo is also a balanced design with a low input impedance. They're really very different amps.

 

[edwtsui]

Yes, just ground the negative input for unbalanced input

Thanks. BTW, do you know any website which provides good documentation of this amp?

The that 340 is made of BJT, not jfet. The new dynalo is also a balanced design with a low input impedance. They're really very different amps.

What's the difference on sounding between BJT and JFET'

 

[cspirou]

The that 340 is made of BJT, not jfet. The new dynalo is also a balanced design with a low input impedance. They're really very different amps.

You are correct. The THAT chips are BJT, not JFET. However you can use JFETs as a few have been built using an adapter PCB for the toshiba transistors you mentioned.

While the toshiba transistors are no longer available, couldn't you use the lsk170/lsj74 from the diyaudio store?

 

[cspirou]

Thanks. BTW, do you know any website which provides good documentation of this amp?

Most of the information is at head-case

 

[00940]

Btw, the dynalo is a nice sounding amp (I've got one) but it's not something worth spending 100$ in jfet.

If I wanted an amp in the same class today, I would rather build a ckiii with BJT input: https://www.amb.org/audio/ck2/

 

[edwtsui]

How's the sounding of CK2 compared with beta22??

 

[00940]

The beta22 is a big powerful amp. Great if you have hard to drive headphones. If you have easier cans to drive, I'm not sure there's any real benefit.

Honestly, all my headamps are gathering dust since I built a small one based on opamps in the feedback loop of one another.

Btw, I found over the years that most of the differences between competent amps were absolutely minor. I'd rather spend money on headphones. They do make a big difference.