Samson Servo 550 studio amp

jkeny · 12th December 2006, 05:29 PM

I just got 3 of these rescued from recycling (don't know if they are working but large heatsinks worth the reclamation alone).

275W output with something like 5 2SA1943 & 5 2SC5200, Heavy duty transformer, 20,000uf Sawha caps.

Specs look reasonably good with THD at 0.07% at 275W.

has anybody heard one of these - what's the verdict - before I strip them down for parts?

John

jkeny · 12th December 2006, 10:39 PM

Here's some specs:

1. Rated Output Power @ 5% @ 1%
At 1 kHz, 4 ohm Model 550 340 W 300 W
At 1 kHz, 8 ohm Model 550 230 W 215 W
2. Total Harmonic Distortion (with 30 kHz LPF, 4 ohm)
Model 550 @ 275 watts 0.07%
3. Signal To Noise Ratio (with 80 kHz LPF, all models)
Channel R 103 dB
Channel L 103 dB
4. Frequency Response (LPF off, all models) 20 Hz - 50 kHz, 0 - 1.5 dB
6. Crosstalk (at 7 kHz sine wave, all models) 85 dB typical
7. Residual Noise (VR min, all models) 73 dB typical
8. DC Offset Voltage (all models) 0 ± 50 mV
9. Idle LED Indicator Output Sensitivity (all models) More than 2.2 V
10. Damping Factor Greater than 100

pinkmouse · 12th December 2006, 10:43 PM

Never had chance to take them apart to have a proper look, but one of the companies I worked for used them and they were reliable and sounded fine. Don't know much else I'm afraid.

jkeny · 12th December 2006, 11:09 PM

Thanks Pinkmouse,
I've got 3 so I will take one apart & use its case, PSU Caps & heatsinks to host a SKA amp - (Greg Ball's amp).

Every time I go to the recycling centre, I find something worthwhile - last month I picked up a Rogers Cadet III tube power amp.

Recyling costs 7 euro per car load which I find outrageous as it should be free but this makes it good value.

John

Zero Cool · 12th December 2006, 11:14 PM

I think these are the same amplifiers used in Hartke Bass amplifers. I have repaired many of those! input grounding is touchy. Most problems are cracked solder connections or gross abuse. most transistors fail open rather then short. so be looking for devices with no connection to one leg. make sure the V-I limiter is working and not clamped closed as these often fail.

make sure to replace all emitter resistors and check all output devices if even one output transitor failed.

Zc

jkeny · 12th December 2006, 11:45 PM

Thanks for the advice Zero Cool. I will check out elements that yo mention.

John

12th December 2006, 05:29 PM	#1
jkeny Banned Join Date: Feb 2007 Location: Dublin	Samson Servo 550 studio amp I just got 3 of these rescued from recycling (don't know if they are working but large heatsinks worth the reclamation alone). 275W output with something like 5 2SA1943 & 5 2SC5200, Heavy duty transformer, 20,000uf Sawha caps. Specs look reasonably good with THD at 0.07% at 275W. has anybody heard one of these - what's the verdict - before I strip them down for parts? John

12th December 2006, 10:43 PM	#3
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Never had chance to take them apart to have a proper look, but one of the companies I worked for used them and they were reliable and sounded fine. Don't know much else I'm afraid. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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12th December 2006, 10:39 PM	#2
jkeny Banned Join Date: Feb 2007 Location: Dublin	Here's some specs: 1. Rated Output Power @ 5% @ 1% At 1 kHz, 4 ohm Model 550 340 W 300 W At 1 kHz, 8 ohm Model 550 230 W 215 W 2. Total Harmonic Distortion (with 30 kHz LPF, 4 ohm) Model 550 @ 275 watts 0.07% 3. Signal To Noise Ratio (with 80 kHz LPF, all models) Channel R 103 dB Channel L 103 dB 4. Frequency Response (LPF off, all models) 20 Hz - 50 kHz, 0 - 1.5 dB 6. Crosstalk (at 7 kHz sine wave, all models) 85 dB typical 7. Residual Noise (VR min, all models) 73 dB typical 8. DC Offset Voltage (all models) 0 ± 50 mV 9. Idle LED Indicator Output Sensitivity (all models) More than 2.2 V 10. Damping Factor Greater than 100

12th December 2006, 11:09 PM	#4
jkeny Banned Join Date: Feb 2007 Location: Dublin	Thanks Pinkmouse, I've got 3 so I will take one apart & use its case, PSU Caps & heatsinks to host a SKA amp - (Greg Ball's amp). Every time I go to the recycling centre, I find something worthwhile - last month I picked up a Rogers Cadet III tube power amp. Recyling costs 7 euro per car load which I find outrageous as it should be free but this makes it good value. John

12th December 2006, 11:14 PM	#5
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	I think these are the same amplifiers used in Hartke Bass amplifers. I have repaired many of those! input grounding is touchy. Most problems are cracked solder connections or gross abuse. most transistors fail open rather then short. so be looking for devices with no connection to one leg. make sure the V-I limiter is working and not clamped closed as these often fail. make sure to replace all emitter resistors and check all output devices if even one output transitor failed. Zc

12th December 2006, 11:45 PM	#6
jkeny Banned Join Date: Feb 2007 Location: Dublin	Thanks for the advice Zero Cool. I will check out elements that yo mention. John

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