I was being sarcastic.
From about ~50 amplifiers i have half is classA, second half is classAB, i got only two classD amps.
Last edited:
You just missed great oportunity there...
https://www.diyaudio.com/community/...4-near-matched-irf-9240-power-mosfets.394827/
Straightforwardness in the circuit and Class A technology
help the Pass INT-25 to amazing performance.
performance. In terms of power and features it is
limited, but not at all in terms of sound.
Matthias Böde
On the short wire
I n handling the new Pass INT-25
I kept thinking about the well-known
HiFi-sentence, according to which an optimal amplifier
amp neither adds to nor takes away from the signal
signal, ergo it is a piece of wire with amplification.
with amplification. If this is the case, the
the renowned manufacturer Pass, based in Auburn, Calif.
Auburn, California, with its INT-25
comes quite close to the ideal. Because single
simplicity of design and short distances are at the
was at the top of its agenda.
Instead of the "Super Symmetry" of the big Pass amps
of the big pass amps, the INT-25, which is much more
INT-25 relies on proven single-ended technology.
ended" technology, which allows for a reduction of the
KEYWORD
negative feedback
By means of a
loop, which connects the input
with the output
signal,
errors like
distortions and
noise are detected
and minimized.
The reduced number of components and the aforementioned
simplification of the functional circuits.
This should at the same time promote the "speed" as well as the
stability of the individual stages, which
which, according to Pass, also leads to less effort
error correction, i.e., negative feedback.
lation, at the same time.
However, this does not mean that the parts
quality is sacrificed in the parts. For example, four of the
four of the complementary components favored by the
four of the complementary field effect transistors
field effect transistors in asymmetrical,
controlled by a current feedback
controlled by a current negative feedback. Here the only three
RCA inputs are managed here, along with a 64-level
level control. A display that can be switched off shows
the selected volume value in blue shining numerical values.
blue numerical values.
The balance setting on the handy metal remote control
on the metal remote control is reserved for the
is reserved for the larger Pass models.
At least the switching of the input trio, muting and
input trio, muting and "power". But
the INT-25, which by the way is directly derived from Pass'
separate power amplifier XA25 was derived,
for which unfortunately there is not even a regulated
preamp output for the purpose of bi-amping,
concentrates on the essentials.
Wide Class A range
This also includes the superb workmanship.
Even the thick front panel, in the typical Pass titanium
typical titanium tone, with the delicate
knob on it is a poem and exudes high-end flair.
and exudes high-end flair. Likewise
the clean interior design plus the cooling fins on both
the cooling fins on both sides.
These are no mere decoration, because the
INT-25 operates over a wide power
range in Class A mode. This means that
that its two 700-Watt/40-Ampère-
FETs per channel are kept open over a high quiescent current
current, which reduces switching distortions when the
distortion during the transition of the signal from the
from the positive to the negative half-wave,
but at the same time leads to high power dissipation,
which then flows into the heat sink in the form of heat.
heat into the heat sink.
Of course, the INT-25 does not push the limits of its final transistors.
of its final transistors. Pass gives it
with two times 25 and 50 watts continuous power
for eight and four ohms, respectively, and
and promises not to exceed the distortion limit of 0.1 percent.
percent will not be exceeded. This is also the case,
as the laboratory determined. That our performance
twice as high (see test profile).
(see test profile) is primarily due to the fact that STEREO
STEREO always measures at one percent
percent harmonic distortion. But it also shows that for
that the amp is by no means finished at the lower
is not the end for the amp. But it just leaves the
Class A range, which is of secondary importance for the
This is probably of secondary importance for the ambitious volume levels.
Those who like to listen louder are usually in the upper
the upper quarter of the level range in terms of numbers.
level control. Nothing against it, because volume
volume controls are there to turn up the volume, and you can
and you can use a normal player, strea- mer or other high
player, streamer or any other high-level device
amp with a normal player, streamer or other high-level device. In case of a
"quieter" source can be adjusted if desired by the
by moving a jumper on the circuit board.
the basic gain from 25 to 31 decibels, i.e. by six dB.
from 25 to 31 decibels, i.e. by six dB.
which provides more headroom,
but at the same time also increases the
very low noise, which is why Pass
is right to use the usually fully adequate, but to a lesser extent
sufficient, but to a lesser extent
boosting setting by default.
Pronounced "clarity
The impression of an amplifier like a
wire that neither omits nor adds anything,
not only with regard to the reduced circuitry, but even more so.
reduced circuitry, but even more so in the listening room.
listening room. There Pass' smallest
not only presented sound images of stupendous directness
directness and control, but also showed differences in
differences between the cables, if not
cable differences, if not more so, then more strikingly than
other high-class amps. Wove these
their character into their performance,
the character of the pleasingly "featureless" INT-25
the INT-25, for example, its tonal tendency
for example its tonal tendency. The radiant
the radiant overtone embossing of an HMS Gran Finale
Finale Jubilee or the golden toned
smoothness of the Cardas Clear - the
INT-25 not only clearly emphasized the typical timbre
of these NF cables clearly.
And three other aspects in the presentation of the
of the American were outstanding:
its three-dimensionality and body, as well as the excellent
and excellent timing. The spatial
front-rear relief of the test titles, including the
of the test tracks was reproduced vividly, including the
of the musicians, whereby singers and soloists
singers and soloists stood out particularly clearly
from their acoustic background.
At the same time, they appeared to be firmly and precisely
in their places and defined down to the finest nuances.
nuances.
When, for example, Lyn Stanley in "Little Drum-
mer Boy", Lyn Stanley held the "M" of "Drum" longer,
you could feel the air flowing through her nose.
through her nose. The passport conveyed the
the physical texture of the articulation,
which also included tiny details in the opening of
lips or other sounds.
You don't want to know that exactly?
Yes, you do, because the insights into the art of
intimate insights into the art of the actors
provides for closeness and tingling tension.
This is also contributed to by the fact that the
INT-25 delicately brings out rhythmic structures
structures. "Saturday Night" by the Red
Norvo Quintet was emphatically snappy around the corners.
corners, which promoted its energizing drive.
while Maria Pihl's "Mal-
vina" made itself comfortable in its wide melodic
in its broad melodic arches, which in turn
the serenity and comfort that the piece radiates.
piece was underlined.
Fluidly resolved rendition
The passport does all this and more
without the slightest hint of analytical
of analytical foregrounding or artifi cial
lishment. On the contrary, it presents itself
a nuance smoother than other amplifiers,
but still very open, fl ink and audible.
In connection with the contoured
the contoured, agile bass, its subtle punch and
punch and its ruby mar- kiness in the lower mids.
in the lower mids. Whether this is
the unusually high damping factor of the output
damping factor of its output stage, which
damping factor of its output stage, by means of which it
the loudspeaker under control? In any case, the impression
fits perfectly into the relaxed, barbless performance of the
performance of the INT-25.
It is also not afraid of higher
higher levels, whereby the
due to the Class A design
of course, enjoyment before power play
goes. The fact that this does not lead to
coloration, but rather the
delicately dissolving Califor-
despite the sunny disposition
always tightly to the point
is what makes his fascination
tion and strength and supports the
supports the impression of being
puristically "on the short wire".
wire" with him.
With this integrated amplifier, Pass proves that you can
with less effort than with the
than with the high-priced bolides of the Americans
amplifiers of high musical expression
expressive power. The Class A technology
the concept that combines subtlety and rhythm
and rhythm with straightforward conciseness.
binated. A top tip for consistently audiophile-oriented
oriented purists, for whom performance and
equipment are secondary.
Measurement results
Continuous power (8 Ohm / 4 Ohm) 58 W / 99 W
Impulse power 4 Ohm (1kHz) 131 W
Clirrf. 50 mW/5 W/1 dB Pmax 0.014 % / 0.006 % / 0.044 %
Interm. 50mW/5W/1dB Pmax 0.005 % / 0.005 % / 1.5 %
Signal to noise ratio at 50 mW/ 5 W 70 / 90 dB
Attenuation factor at 4 ohms (63 Hz/1 kHz/14 kHz) 200/182/89
Upper cut-off frequency (-3 dB/4 Ohm) >80 kHz
Crosstalk Line 1 > Line 2 74 dB
Volume synchronization error at -60 dB 0.1 dB
Stereo channel separation at 10 kHz 43 dB
Power Rec. Stby/idle (at) <0.1 W / 165 W (225 volts)
Lab comments
For most cases
completely sufficient
performance, very low
distortions in the Class A range as well as
pleasantly high signal-to-noise ratios (measured at the preset
measured at the preset 25 decibel gain),
moderate channel separation, precise volume control, higher
higher idle power consumption typical for Class A amplifiers.
power consumption in idle mode.
You have now set a record 🙂
The longest text post ever ......
The longest text post ever ......
240/9240 are what i use most
Lu1014 power jfet is not easy to work with, but its cheap and available and plenty of circuits to try, f3, lufo, susylu, ludef, f1j...
Lu1014 power jfet is not easy to work with, but its cheap and available and plenty of circuits to try, f3, lufo, susylu, ludef, f1j...
It looks
And reads more
Like poetry too.
Wouldn’t score well on the essay portion of a college entrance exam either. But it probably does exceed 1000 words.
+1 on the 240/9240 - this is a case where the original is still the best. You don’t need .0005 ohm on resistance when it costs real-world SOA and you put emitter resistors on them anyway.
Hej! Thats hi in swedish, i just came from ikea.
Those j200/k1529 are great, i built some amps with those. Some of the circuit posted on that page are just concepts or work in progress.
Those mosfets are long gone.
Those j200/k1529 are great, i built some amps with those. Some of the circuit posted on that page are just concepts or work in progress.
Those mosfets are long gone.
I just added SPICE Models for 2SK1530 and 2SJ201.
Those models are by Cordell.
But tested those models and found they have a very low VGSon.
Way lower than the specified min of 0.8 Volt.
Anyone else have used those models?
Those models are by Cordell.
But tested those models and found they have a very low VGSon.
Way lower than the specified min of 0.8 Volt.
Anyone else have used those models?
I don't understand what you guys do with the obsolete 1530/201 or 1529/200.
You do for real or you just simulate ? 😉
You do for real or you just simulate ? 😉
I'm lucky enough to have a stash of matched 1530/201's. I've built 8 odd amps with them. As far as the Cordell models go.. I use them but have never questioned them. (I'm in no position to do so!) With about -1.5v VDS on the P device I get 120mA bias. That seems about right?