Edcor OPTs for Class A ss amps

[andyjevans]

I'm relatively new to solid state amps - I think and build tubes. I'm intrigued by some of the new generation ss devices, like lateral MOSfets and Semisouth devices. Thinking along tube lines, I'd be interested to try a build with OPTs. Have a look at these Edcor Class X OPTs and tell me which of these could be used, and suggest schematics I could look at! I'd be wanting about 12W or a bit more for a fullrange Alpair 10 unit (like JX92) about 88db.

Below is SE 600 ohms to 8 ohms, rated 250mA
EDCOR Electronics Corporation. CXSE25-8-600

Below is SE 150 ohms to 8 ohms, rated 400mA
EDCOR Electronics Corporation. CXSE25-8-150

Below is SE 300 ohms to 8 ohms, rated 400mA
EDCOR Electronics Corporation. CXSE25-8-300

Below is PP 1.7K ohms to 8 ohms, rated 100W
EDCOR Electronics Corporation. CXPP100-MS-1.7K

 

[kenpeter]

For high Voltage, don't neglect to look into IGBTs.
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00229142.pdf

Anyways, McIntosh'd solid scrape amps had like 2 ohm output.
An auto transformer was used to bring that UP to 8 ohms...

I'm guessing high voltage transistors weren't good enough yet?
They chose to go the way of high current instead...

 

[jcx]

for SS amps a xfmr only adds distortion - unless you care about extreme fault protection for the speakers I can't see the point today

 

[Pano]

I dunno, I've heard a few mighty fine (and clean) SS amps with output iron. Seems strange, but can sound good.

Edcor will wind custom transformers if you can figure out what you need.

 

[hitsware]

It depends on which devices you use.
In general the lower impedance primaries
would be better ......
(if only to keep the rail(s?) lower)
for both safety and cost concerns

 

[andyjevans]

I'm OK for rails up to 300v, since I use tube equipment anyway. I don't know much about devices like the Semisouth ones - which are rated 1200v - or also there's the Russian KP926. I have some curves for that which suggest 55v at 150mA. Wrenchone has been running the 085 at 300v and 150mA as far as I can see. On the other hand, Nelson Pass ran the 085 at 35v. I'm totally new to these devices, so I don't have much idea yet about what primary to go for. I'm used to seeing curves for triodes, and I'm a bit in the dark here.

 

[pieter t]

Andy,

May I suggest also to look at Susan Parker's thread here, and her website (very well documented).
PP transformer coupled SS amplifier; SE possible if you want some additional distortion😀
In stead of fet follower - step up transformer for voltage amplification you could use your beloved 26 stage.

 

[andyjevans]

I know Susan - she lives close by and we are both in the London Audiocircle. She uses a quite expensive Sowter transformer. We've talked in a preliminary way and when she has some free time we'll talk further. Yes - that's the idea, to use the 26 stage. I have various interstages from Lundahl which can step down or up. Down I would think from a 26! I think various people are working on some of the new devices with OPTs.

Andy