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Old 19th October 2006, 01:16 PM   #11
quasi is offline quasi  Australia
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Default Re: who s got the best schematic?

Quote:
Originally posted by seanmacss
who has the best schematic to build a 100w to 1000w
iam just wondering wich is the best power amp to build???

Quote:
Originally posted by richie00boy
Best for what? Ease of build? Cheapness? Sound? Measured performance?

One mans best is another mans rubbish.

There are a some great amps designed by DIYA members available here. Each is great for different reasons and have been designed from different points of view.

If you are interested check out my ideas here. This amp design was intended to be;

- cheap
- high quality
- powerful
- flexible in terms of components and power
- easy to build.

This link takes you to the middle of the relevant thread Power amp under development and this one to a document with all the details http://www.raindogindustrialarts.com...2006-05-06.pdf

The amp can be built to suit powers from about 80 watts to over 500 (4 ohms).

Cheers
Q
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Old 19th October 2006, 06:49 PM   #12
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Due to the initial question of this thread, perhaps design defense is appropriate. My device brings reduced open-loop gain, and with it comfortable and precise transient response and low increasing order of distortion. It utilizes complementary symmetry throughout, just like music might. Its dynamic response is well-attended; no saturation, no casual current limiting (only for low-ohm / short circuit output loads), no current mirrors. It has lots of feedback pathways, but comparatively low 'quantities' of feedback. Similarly it can be made more or less powerful with relative ease. I would be pleased if people wanted to build it and then tell me what they find wrong with it or suggest improvements. I'll be checking my email for queries for it...

My design philosophy embraces the fact that transistors can be very well-disciplined if not coerced into violence.

Quasi - don't thermally track the output FET's too closely... I'd place T8-T10 on their own small heatsink together, because the bias needs to track the bipolars only, especially T10 since it gives the only local feedback for the negative output polarity. FETs increase resistance the hotter they get.
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Old 20th October 2006, 12:48 AM   #13
quasi is offline quasi  Australia
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Quote:
Originally posted by acoustixman
Quasi - don't thermally track the output FET's too closely... I'd place T8-T10 on their own small heatsink together, because the bias needs to track the bipolars only, especially T10 since it gives the only local feedback for the negative output polarity. FETs increase resistance the hotter they get.
This is true for the FETs that SuzyJ used but not true for the types of FETs used in my amp. In this case transconductance increases with temperature. As the attached chart shows this is true for currents up to almost 20 amps and this unfortunately is more than the FET can handle.
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Old 20th October 2006, 02:12 AM   #14
Leolabs is offline Leolabs  Malaysia
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LATFET or HEXFET???
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Old 20th October 2006, 04:08 AM   #15
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Are you good enough to figure out the schematic to the amplifier with the best specs? Just like Jeprody....


DMA-360 Monaural Power Amplifier
Power Output
(continuous): @ 8 ohms - 300 Watts RMS
@ 4 ohms - 533 Watts RMS
@ 2 ohms - 680 Watts RMS
Output Compliment: 90 Amps peak
Frequency Response: +-0.1 dB, DC - 150 KHz
+-1 dB, DC - 1 MHz
+-3 dB, DC - 1.8 MHz
Distortion
Static: less than 0.015% from DC
to 100 KHz, typically
0.009% @ 300 WRMS/8 ohms
Dynamic: 8 Tone Cluster Test 20
KHz @ 500 Hz separation
0.01% @ 8 ohms
0.015% @ 4 ohms
Speed:
Risetime: less than 300 nanoseconds
Settling: 1.5 microseconds to -40 dB
Slew Rate: 600 volts/microsecond
Noise:
Signal to Noise: 97 dB nweighted,
107 dB ASA A
Crosstalk: 98 dB @ full power 8 ohms
Input:
Impedance: 10k ohms
Sensitivity: 1.5 volts / nominal output
Power Supply:
Line Voltage: 100 volts, 120 volts,
240 volts (internal wiring)
AC Voltage Range: +-10%
Maximum Consumption: 2000 Watts
Quiescent Consumption: 250 Watts

Operating Temperature: 0 deg. to +50 deg. Cesius range,
32 deg. to +122 deg. Fahrenheit
Protection Features:
DC Protection Servo: .5 volt range
Current Limit Onset: 90 Amps
Thermal Threshold: Protects at 85 deg. Censius,
185 deg. Fahrenheit

AC Main Fuses: 120v 5A or 220v 2.5A slo blo
Size and Weight:
Dimensions: 20" (50.8 cm) W,
7.23" (18.4 cm) H,
19.6" (49.9 cm) D,

Weight: 67 lbs, 30.4 KG Net


UNPARALLELED RESOLUTION, UNPRECEDENTED POWER


The very high-speed launch and enormous current reserves of the DMA-360 are made possible with the use of Spectral's proprietary "Focused Array" construction. This breakthrough topology aligns high-current vertical fet output devices for rapid, pistonic signal launch. The output section is comprised of eight individual V-FET amplifier modules paralleled to achieve a minimum 300 watt RMS output with 90 amp capability, and full rated power is delivered with absolute load stability at an unprecedented 1 MHz. Output current is approximately double that of any previous high-speed amplifier design. The "Focused Array" output section design of the DMA-360 makes possible the practical use of ultra-fast vertical fet devices for the first time in a high powered audio application. Each device, having vacuum tube like operating character, is energized from its own dedicated high energy storage capacitor, rectifier, and individually powered from an isolated ultra-low coupled transformer winding. Individual teflon bias trimmers calibrate each V-FET output device separately for maximum linearity and precise alignment. Groups of these individually powered output sections utilize field folded RF type construction and electronic shielding to banish noise and eliminate low level propagation of stray interference. The resulting "Focused Array" of eight individually powered output sections performs as one with virtually no cross-coupling or energy storage artifacts reflecting between output devices. During extreme program dynamics, this arrangement can launch an instantaneous high-current drive of over 90 amps to the most sophisticated loudspeakers with unprecedented waveform tracing precision. Gone are performance damaging magnetic and electrical field propagation problems of conventional high-powered amplifier construction. Without stray radiation, critical small signal paths within the DMA-360 can perform with lowest possible distortion and settle to signal extinction in millionths of a second. Hence, the DMA-360 works with high power and great speed yet behaves inert to other system components. Reproduction is extremely articulate and naturally resolving yet has all the powerful unlimited sonic character of the most brutal high power amplifier designs. THE POWER VAULT

The Focused Power output section of the DMA-360 is only one of the many Spectral innovations designed to create the ultimate in amplifier control and resolution. A unique transformer architecture supports the critical requirements for lowest noise and high power capability of the powered output section array. In traditional high-end power amplifiers, output transformers are located away from active amplifier circuitry for purposes of noise isolation and construction ease. This virtually universal method extracts a significant sonic price, however, because of the speed and regulation losses which are imposed by the long power supply wiring harness. In addition, the EMI and noise which radiate from the supply harness invariably contaminate sensitive low level circuitry by noise modulating the musical signal. Spectral engineers have long recognized the problems associated with power supply noise contamination and have proposed a unique solution in the DMA-360 Monaural Reference Amplifier. The Power Vault electromagnetic field containment system virtually eliminates EMI radiation to the amplifier signal path circuitry as well as power and regulation losses through the traditional power supply harness. The architecture starts with Spectral's elaborate high performance custom power supply transformers. These unique designs are the result of years of research and development to maximize isolation and regulation. Each transformer features individual isolated windings to support each individual output transistor in the amplifier output section. The twin power transformers are mounted between massive machined mounting plates for damping and resonance control. The combined 38 lb. Transformer structure is then mounted on a constrained rubber floating suspension system similar to a fine turntable suspension. The finished transformer assembly is then suspended inside an EMI, RFI tight welded aluminum containment box located directly beneath the DMA-360 output section. The resulting transformer Power Vault containment system results in an uncompromising solution to the universal power supply noise problem. The high-current power transformers are now intimately sited next to their own high-current output devices with extraordinary noise isolation. The high-speed driver circuitry of the DMA-360 operates in a pristine environment free of the noise radiation and phantom signals which plague other power amplifiers. Dynamic range limitations are removed with a sonic clarity and quietude which are palpable.

ULTRA PREMIUM DISCRETE CIRCUITY

Small signal circuitry is based on Spectral's proven discrete circuit multiple cascode double push-pull FET technology. Premium silicon array construction, similar to circuitry in the DMC-20 Reference Preamplifier, is applied to the DMA-360 to achieve enormous internal dynamic range capability. This reserve is linear class A with many times greater dynamic capability than program demands. It allows high current drive for quick controlled response from the very large output V-FETs as well as isolation from their internal electronic activity. Unhindered by interferences and slow cumbersome response of conventional practice, these parts operate with unyielding control and exacting precision. Reproduction is clean, effortless and highly holographic. Audio amplification paths through the DMA-360 are direct, inherently linear and simple. These minimalist configurations have always sounded and measured best but normally become ponderous and overburdened when protection and support functions are added. The DMA-360 takes a different route to solve the sonic problems of amplifier protection circuitry. To maintain the pristine signal path, a sophisticated analog computing ancillary system is thermal and opto coupled within the amplifier. This "hands off" operational management system observes device loading and power dissipation as well as speaker damaging out of range signals. It takes control without circuitous cross interfering connections to electronics in the signal path, leaving the musical signal pure and totally untouched.


A REMARKABLE TOPOLOGY

The DMA-360 utilizes custom FETs and high speed bipolar transistors in a dense, fully balanced topology to achieve high-current launch and ultra-fast settling capability. RF (radio frequency) design techniques are employed to achieve a DC coupled power band with intrinsic bandwidth to almost 5 MHz!
Input Stage.
The shielded input stage utilizes a balanced, double cascode design using matched differential pairs of J-FETs. The cascode design derives its own ground reference and produces extremely high levels of isolation from the preamplifier and between the stages of the DMA-360 itself.

Gain Stage.
The gain stage utilizes super high frequency (RF) bipolar transistors matched in a cascode configuration to bring the circuit gain into the power device realm.

Output Stage.
The output stage consists of eight individually powered VMOS-FET output amplifiers. This precision amplifier array features individual push-pull drivers, high-speed power supplies and individual biasing to function as a single ultra-fast, high current output section. The result of these techniques is unprecedented fast settling and remarkable intertransient silence.
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Old 20th October 2006, 11:19 AM   #16
jez is offline jez  United Kingdom
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Suzy,
Nice work on that amp! I've followed most of the thread about your diy ETI.....
Just one point here though, the distortion graph you have posted above shows a rapid rise at low frequencys. If this is not due to the measurement set up then it could be worthwhile taking another look at the type and values of the feedback capacitor/s (if this design uses any...don't have schematic in front of me ) and rail decoupling caps.....just an idea
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Old 20th October 2006, 11:31 AM   #17
suzyj is offline suzyj  Australia-Aboriginal
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Quote:
Originally posted by jez
Suzy,
Nice work on that amp! I've followed most of the thread about your diy ETI.....
Just one point here though, the distortion graph you have posted above shows a rapid rise at low frequencys. If this is not due to the measurement set up then it could be worthwhile taking another look at the type and values of the feedback capacitor/s (if this design uses any...don't have schematic in front of me ) and rail decoupling caps.....just an idea
Hiya Jez,

Thanks for the compliments.

I don't think the rise at low frequencies is real. The distortion analyser has a high pass filter to reduce the influence of mains hum, so at low frequencies it's working with lower levels, hence the noise floor goes up.

Cheers,

Suzy
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Old 20th October 2006, 11:51 AM   #18
wputera is offline wputera  Indonesia
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hello Suzy. I dont have sst 404 dual jfet. if i like to build aem 6000 with 2sk246 replacing sst 404, what will happen with my amp?it is save for my amp. coz i have 6 pairs of 2sk1058-2sj162 and i like to build a good amp with easy component to build my amp.

hello quasi. keep your good work. i will build your quasi amp too with 5 pairs but i only have 45v-ct-45v 15A transformator, how many watt if my speaker 4 ohms and 8 ohm.

Thank you all good guys n good girls
God bless U all.
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Old 20th October 2006, 12:09 PM   #19
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Be around 400 watts into 4 ohms, maybe a little less. Probably about 220 watts into 8 ohms. 5 pairs of devices is fine for the 4 ohm load.
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Old 20th October 2006, 12:42 PM   #20
suzyj is offline suzyj  Australia-Aboriginal
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Quote:
Originally posted by wputera
hello Suzy. I dont have sst 404 dual jfet. if i like to build aem 6000 with 2sk246 replacing sst 404, what will happen with my amp?
I don't know off-hand. As long as it's good for better than 15V Vds it should work okay.

Mouser has SST404s. They're pretty cheap.

Regards,

Suzy
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