Active hi-fi system spherical 2 way speaker /power amps/ preamp / phono

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spresto9
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Joined: Tue Jun 17, 2008 10:53 pm
Location: South Essex

Active hi-fi system spherical 2 way speaker /power amps/ preamp / phono

Post by spresto9 » Fri Nov 10, 2017 4:08 pm

Active hi-fi system spherical 2 way speaker /4 mono power amps/ preamp / phono

OK this is not for the feint hearted, a good knowledge of system and amp design would be useful as there are no circuit diagrams
Custom built system spherical 2 way speakers 4 mosfet power amps, crossovers, passive preamp with phono stage and relay source select, fully balanced lines
Massive power supplies
I acquired the system 10 years ago when a friend passed away, he developed the system over some years and was firm believer in function over form, its messy and untidy but has performed flawlessly for me almost every day for 10 years it sounds fantastic, dynamic with great drive and imaging.
His design belief was there any amp was basically of system to modulate the power supply hence the massive supplies and the use of many voltage regulators, over 25 in the system in total.
Listening can be arranged but the system must be collected as it has a total all up weight of about 130 kilos!

Photos at :-https://drive.google.com/drive/folders/ ... sp=sharing

Speakers
2 way spherical 35lt ported enclosures made from sandwiched MDF and plaster lined (extremely heavy)
10” Volt BM250 Bass drivers.
Monitor audio metal dome tweeter.
With Perspex tube mounts plus heavy floor stands that bolt on.
Fast, dynamic and great imaging

Bass Amps
Custom designed mosfet amp (4 output devices) DC servo circuit
Balanced line receiver (AD ssm2143)
Massive power supplies 1kva 50v for output only + 125va 55v regulated for driver stage and servo

Tweeter Amps
Custom designed mosfet amp (2 output devices) roughly based on Hitachi circuit
Balanced line receiver (AD ssm2143)
Massive power supplies 600va +/-50v transformer for output devices only
125va +/- 55v transformer, voltage regulated for driver stage and line receiver (separate regulators)

Passive Preamp / phono / crossover / balanced line driver
Relay selection of 5 inputs + phono
Phono based on JLH design using op-amps (AD797/LT1037) each op-amp has its own +/- voltage regulator
Linkerwitz 24db crossover
Balanced line drivers to power amps (AD ssm2142)
System timed turn on, instant off mute
Every circuit has its own voltage regulators

Switch box /preamp power supply
Switches all system/power amps on sequentially
Also contains massive power supply for pre-amp

All cables and stands included
Pm me with any questions
£1000 ono
Located in Essex

*Note source components not included.
Attachments
Petes system 2017-10-24 004 (640x427).jpg

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