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Holton Precision Audio
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Holton Precision Audio

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Welcome to HPAs first Newsletter for 2015.
This year I hope to release a number of new products, this will include a pre-amplifier board, stand alone DC Servo, Balanced to Single Ended input amplifier to name a few.
To start off 2015 I have a couple of new products to show you.
The first one is the extreme version of the NXV1200L, this amplifier has been beefed up to the max with double the amount of output stage power supply filtering and improved and enlarged PCB layout.
The second new product is the NXV101L Signature Mono Block Amplifier.
This module uses a single pair of Exicon dual die lateral MOSFETs for much improved power output compared to the NXV101 R2 module. It also has improved power supply filtering with 12 x 4700uf 80 volt capacitors in is power supply. Signal to Noise Ratio has also been improved to over -112dB with respect to full output.
Power output for this module is up to 180 watts into 8 ohms and 300 watts into 4 ohm loads.
Visit holtonprecisionaudio.com for more information.
HPA-NXV1200LE Mono Block Amplifier
1200 Watts RMS into 4 Ohms
700 Watts Into 8 Ohms
64800uf of output stage DC filtering
THD+N = 0.05% SNR = -100dB
DC Servo to correct DC offset to less than 1mv
See photo below.
HPA-NXV101L Mono Block Amplifier
300 Watts RMS into 4 Ohms
200 Watts RMS Into 8 Ohms
56400uf of output stage DC filtering
THD+N = 0.005% SNR = -112.8dB
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Holton Precision Audio

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The development continues with the 20 watt Class A module. So far THD has been reduced to 0.004% at 15 watts into 8 Ohms and -103dB SNR. Not too bad at this stage. But looking for a little bit more. What has come out of this development is the importance's of isolating the input-driver stages from the output stage power supply. Just adding a little bit more supply decoupling between the input and output supplies helped the THD to be reduced from 0.005% down to 0.004%. It may not seem much but it is the difference between 50ppm and 40ppm. I think the Volt One regulator could be a great addition or at the very least an option for the 20 Watt Class A amplifier module.
What is even more interesting is this performance has been achieved on my dirty 2kw VARIAC controlled power supply. So I think once I get this module on its own clean power supply it just might look even better.
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Holton Precision Audio

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Here is some more THD figures to munch on for the 20 Watt Class A amplifier module.
The following THD figures were just measured on my Boonton 1120 Audio Analyzer with a 80khz bandwidth measurement.
At 15 watts into 8 Ohm load.
1khz - 0.004%
10khz - 0.006%
20khz - 0.0074%
30khz - 0.0078%
40khz - 0.0082%
I kind of stopped here, suffice to say this amplifier is very linear indeed!
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Holton Precision Audio

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Just a few notes on what has been happening; I have being working on a Push Pull Class A amplifier design, It will be in the 20 watt range into 8 ohms. One of its key features will be active output stage current monitoring and DC offset servo built in.
The prototype is working great, the output stage bias can be set to bias setting in the range of 20ma to 5 amps and because of the active monitoring the current locks into place regardless of voltage supply or heat sink temperature. It is really impressive to watch an amplifier draw 2 amps through its output stage using output devices such as the Toshiba 2SK1530 or the IRFP240 devices and the current setting does not budge. Only varying +-8ma as the heat sink warms up. The new module will have a gain setting of around 26dB or less depending on its application, ideally suited to the higher efficiency loudspeakers and the module will have a DC offset of less than 1mv because of the on board DC Servo.
High End Handcrafted Audio Amplifiers
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