Has anyone in diy land ever added a set of mosfets to a DH-200 or DH-220? The Hafler P-230 has an extra set of mosfets as does the XL-280. If so, is the benefit being able to drive lower impedance loads?
I added an extra set of outputs to a DH 200, but you need to match the set of 3 positives and the 3 negative devices for equal Vgs .( I had enough extra devices) . Also you need to set the bias to at least 350 ma ( more bias would be nicer but watch for thermal shutdowns). Yes more drive into low impedance loads, but the heatsinks are the limitation thermally.
Thank you for the input. By chance are there any photos of the unit with the modifications? We’re the results of the modifications worth the time and effort? Would you do it to another unit in the future?
IMHO, you can, but be super careful of stability as of course the outputs are not available, so if you blow them you will have to convert to Exicons.
Of course if you want a 280, just watch for one. Safer.
Of course if you want a 280, just watch for one. Safer.
Frankly, I would not bother. Doing it on a budget is one thing (not mine)
building a super amp without limits may require a different approach.
Or approaches. 😉
It would be easiest to buy/use a matched sets of (single die) Exicons, 4 per side
that would in effect, give you "the same" electrically as the 6 per side
on P230 or XL280. It will cost you... but worth it. Far less effort
and experimentation, than "adding" extra outputs.
I like (much prefer) the character of 6 devices, I like the
"current dumping" effect with greater body and weight.
That is ~ with ~ a beefy PS. Stock PS are too anemic.
Sort of off topic ~ but related. I have been listening to several builds,
the past 6 months, with 6 single Exicons with 82 volt power supplies
("challenging" ' testing the heatsink capacity) running 8 ohm loads.
(L) 63 volt amp / (R) 82 volt amp, on image 2.
Well, I like it SO MUCH, I have plans >in the works< for a "XL280"
with "Hafler 500" power supplies, on a 200 chassis.
It had to be 2 story to fit. Stay tuned... 🙂
Beefy power supplies were required to deliver on this...
building a super amp without limits may require a different approach.
Or approaches. 😉
It would be easiest to buy/use a matched sets of (single die) Exicons, 4 per side
that would in effect, give you "the same" electrically as the 6 per side
on P230 or XL280. It will cost you... but worth it. Far less effort
and experimentation, than "adding" extra outputs.
I like (much prefer) the character of 6 devices, I like the
"current dumping" effect with greater body and weight.
That is ~ with ~ a beefy PS. Stock PS are too anemic.
Sort of off topic ~ but related. I have been listening to several builds,
the past 6 months, with 6 single Exicons with 82 volt power supplies
("challenging" ' testing the heatsink capacity) running 8 ohm loads.
(L) 63 volt amp / (R) 82 volt amp, on image 2.
Well, I like it SO MUCH, I have plans >in the works< for a "XL280"
with "Hafler 500" power supplies, on a 200 chassis.
It had to be 2 story to fit. Stay tuned... 🙂
Beefy power supplies were required to deliver on this...
Attachments
Ozark,
How about using two 220 chassis and make mono blocks. Lower voltage, but all the current you need.
I run a modified 120 with exicons. Converting to Miller compensation, 4 times the rail caps and a few other tweaks, quite nice. Not a power house, but I don't need one.
How about using two 220 chassis and make mono blocks. Lower voltage, but all the current you need.
I run a modified 120 with exicons. Converting to Miller compensation, 4 times the rail caps and a few other tweaks, quite nice. Not a power house, but I don't need one.
Be SUPER CAREFUL buying XL280 (and XL600) FWIW.
The front ends [on most] are "out of tolerance", DC offset is too high
with no means of adjusting and NO REPLACEMENT FETS!
Test these amps (people never do) for DC offset before buying one.
The image shown, XL600 .after. the "protection relay" connect
to speaker load...
This amp saw a resistive load, never drove any of my speaker
until completely rebuilt [ditched the stock boards]
it was unusable (as sold to me)
The front ends [on most] are "out of tolerance", DC offset is too high
with no means of adjusting and NO REPLACEMENT FETS!
Test these amps (people never do) for DC offset before buying one.
The image shown, XL600 .after. the "protection relay" connect
to speaker load...
This amp saw a resistive load, never drove any of my speaker
until completely rebuilt [ditched the stock boards]
it was unusable (as sold to me)
Attachments
I went this lop-sided amp direction, to fit the PS into a (single) chassis.
I have (4 pair) 8 similar mono amps, built in different configurations...
but as identical mono pairs, by using the chassis tops as chassis pans.
The XL280 (not shown) was for simply sh!ts and g!ggles!
Actually more like a "Hafler 500" .without. a fan.
~ the HIGHER voltages ~ to me, result in a more "propulsive" sound,
with greater weight and body, all desirable. Struggle for a word.
