São Paulo – Brazil August Meet

[spritzer]

This has nothing to do with liking how something sounds.  Plenty of people like Hifi-man and Ultrasone headphones even though they are dreadful.  Just flip over the Stratus and look inside, the cheapest possible iron which everybody agrees makes or breaks an amp.  Lousy circuit design and a "DC" filament supply which will burn up the tubes.  What's not to like....?

[DefQon]

I liked the Stratus with the HD800  

 

But I ain't ever seen the insides nor spend $3.4k on it. Still prefer the Manley Neo 300B for HD800's. 

 

DC filament supply? Regulated or no? I thought it was good thing for some designs as AC could induce noise inside. (Unless I'm mixing heater and filament around).

[spritzer]

For any filament or heater supply you have to regulate the DC which DNA doesn't do.  A simple LT1083 supply would be great for heaters (a 7805 with a diode on the ground terminal also works just fine) but for DHT filaments you need a high frequency switcher to get optimal tube life. 

 

These tubes were never supposed to use AC for the heaters as a tube like the 300B was supposed to use batteries for the filament.  It's what they had at the time and explains the low voltage. 

[tin ear]

and this dramatically shortens the life of the tubes?

[spritzer]

Yes. 

[kevin gilmore]

what is the amp with the horizontal green stripes top and bottom?

[skullguise]

That's the POS  Leben

[Mario_Fpolis]

http://lebenhifi.com/products/cs300xs.html

[spritzer]

Behold the glory...

 

[nopants]

but, but ...it has hand wound transformers

[DefQon]

Add headphone output to a 6BQ5 Marshall tube guitar amp, bump up the distortion = CS300X.

[kevin gilmore]

so lets see

 

cross coupled cathodes... Nope

ultralinear... Nope

enough gain to lower distortion... Nope

local feedback around the phase inverter... Yup and bad too

etc

 

why didn't they just copy the mc40

[spritzer]

I knew you'd like it.    It's funny though that the 136$ SET kit I've been playing with has a better PSU design than this pile of fail.  A good point is the "DC" supply for the 5751 heaters.  That's not how you are supposed to do it...