Hi, Tiefbassuebertr
The extrusion company is "EDICO". They said that this extrusion profile is actually a custom one, (for telecomunication company at that time). They still have the moulding, but we have to buy minimal 1 ton of aluminum.
I don't have the documentation of the making of this amp. Basically it is an F5 with 12V SMPS.
Sound is nice (how should I say this ?
)
I think F5 can work in AB mode. So I'm not using the bias value recomended by the article, I use less than that. The amp draws about 5A at 12VDC. I can adjust the bias value to the article value, but it just toooooo hot for my current heatsink
The extrusion company is "EDICO". They said that this extrusion profile is actually a custom one, (for telecomunication company at that time). They still have the moulding, but we have to buy minimal 1 ton of aluminum.
I don't have the documentation of the making of this amp. Basically it is an F5 with 12V SMPS.
Sound is nice (how should I say this ?
) I think F5 can work in AB mode. So I'm not using the bias value recomended by the article, I use less than that. The amp draws about 5A at 12VDC. I can adjust the bias value to the article value, but it just toooooo hot for my current heatsink
Today I run a Soundstream MC140x in my car, and I've been telling people it's design roots are of Nelson pass. I beleive the MC series of amps were similar to the Dxx series of the time - MC being the higher end. Its a Class-B design using TIP102/107 otuputs.
Am I correct in calling this amp a Nelson Pass?
This is not an NP design , well i dont think so , the Class A-40-50 d40, d60
d100, d200 were, the early ones ..
The Class -A 40 was the best sounding of the bunch IMO , they would thermal shut down on a hot day , so they did an Class-a 50 with reduced bias. We used to run cooling fans on them to prevent thermal shut down.
Still have a few ....
When I was doing remote recording, I had a Soundstream D200 driving ADS200s in a station wagon. The speakers could be swiveled to face backwards towards the tailgate where a Studer 169 mixing console rested. Great portable monitoring system. I acquired the Soundstream after a fellow Acoustat owner, who had Thresholds, told me that Maestro Pass had a hand in their design.
A2125
The A 2125 which Zed built for Alphasonik in 1985 was a regular class B amplifier using TIP35/36 for the amplifier and TIP35 for the switching supply. We ran the supply at about 25KHz as this was the limit for TIP35's. Unfortunately good MOSFETs were not available at that time.
The sliding bias was based on Threshold's patent but it could never be biased so that the output stage ran at any decent level of class A.
This was pretty much the same design as the early Hifonics which we were producing at that time.
Steve Mantz
Zed Audio Corporation
The A 2125 which Zed built for Alphasonik in 1985 was a regular class B amplifier using TIP35/36 for the amplifier and TIP35 for the switching supply. We ran the supply at about 25KHz as this was the limit for TIP35's. Unfortunately good MOSFETs were not available at that time.
The sliding bias was based on Threshold's patent but it could never be biased so that the output stage ran at any decent level of class A.
This was pretty much the same design as the early Hifonics which we were producing at that time.
Steve Mantz
Zed Audio Corporation
That would be it... I didn't see it mentioned in this thread... That was a lovely sounding amp..
Alphasonik A2125
The A-2125 (circa 1984) was TIP142 x 3 + TIP147 x 3 per channel.
Regulated power supply is SG3524 with 8 x TIP35.
Has banana jacks for power and speakers.
The A-2125 Mk II (circa 1985) was TIP35 x 3 + TIP36 x 3 per channel.
Regulated power supply is TL494 with 10 x TIP35
Fixed power wire and molex for speakers.
I designed this amplifier in 1984 and it NEVER used TIP142/147 devices. and I have NEVER designed using SG3523 PWM chip.
Where people get their information is beyond me.
So please "oPossum" check up before posting inaccurate information.
Another post by tsmith1315 says "Current limited TIP35/36 amps using a 555 timer-based SMPS.". Never uses a 555 timer in my life so where this comes from is again.........beyond me.
In those days I did indeed use the TIP35C/36C and still today I use the TL494 as it is much more versatile than any SGxxxx chip.
As to class A amplifiers for the mobile industry, it is simply a fantasy. Does anyone know what the efficiency of a push pull class A amplifier is?
Class A is defined as the idle current must be equal to or greater then the peak load current. I personally do not agree with this as the impedance of a speaker is not constant and the speaker has reactance. So an amplifier designed to run PURE class A into say a 4 ohm load MUST take into account these things and therefore should be capable of at least PURE class A operation into a 2 ohm load.
A single channel PURE CLASS A 25 watt 4 ohm amplifier with switching supply draws massive current from the battery. Typical real world efficiency is less than 25% just for the amplifier and maybe 90% for the power supply.
This would dissipate about 83 watts constant from the battery = 7Amps.
So a 125w/ch like the A2125 would be enormous and draw over 83 amps continuous from the battery.
So again pure class A for mobile is a pipe dream in any meaningfull power category.
zed only built the A215 in Los Angeles and in fact was the only amp we built for Akphasonik until the late 90's.
Yeah the Soundstream Class A was just a slightly over biased version of these early Soundstream amps but 100% not a class A amplifier.
Someone take some TIP142/147 and bias them hard using the 0.1 ohm emitter resistors used and see how quickly these TIPs turn to ash.
Always amused me how convinced people are when some company advertises "Class A" and they believe the BS put out by these companies who know less than zero what class A really is.
Finally I have never met Nelson Pass but have the utmost respect for him and the designs he has put out. I have read many articles and interviews about Nelson and have found him to be a modest and humble guy.
Steve Mantz
Zed Audio Corporation
The A-2125 (circa 1984) was TIP142 x 3 + TIP147 x 3 per channel.
Regulated power supply is SG3524 with 8 x TIP35.
Has banana jacks for power and speakers.
The A-2125 Mk II (circa 1985) was TIP35 x 3 + TIP36 x 3 per channel.
Regulated power supply is TL494 with 10 x TIP35
Fixed power wire and molex for speakers.
I designed this amplifier in 1984 and it NEVER used TIP142/147 devices. and I have NEVER designed using SG3523 PWM chip.
Where people get their information is beyond me.
So please "oPossum" check up before posting inaccurate information.
Another post by tsmith1315 says "Current limited TIP35/36 amps using a 555 timer-based SMPS.". Never uses a 555 timer in my life so where this comes from is again.........beyond me.
In those days I did indeed use the TIP35C/36C and still today I use the TL494 as it is much more versatile than any SGxxxx chip.
As to class A amplifiers for the mobile industry, it is simply a fantasy. Does anyone know what the efficiency of a push pull class A amplifier is?
Class A is defined as the idle current must be equal to or greater then the peak load current. I personally do not agree with this as the impedance of a speaker is not constant and the speaker has reactance. So an amplifier designed to run PURE class A into say a 4 ohm load MUST take into account these things and therefore should be capable of at least PURE class A operation into a 2 ohm load.
A single channel PURE CLASS A 25 watt 4 ohm amplifier with switching supply draws massive current from the battery. Typical real world efficiency is less than 25% just for the amplifier and maybe 90% for the power supply.
This would dissipate about 83 watts constant from the battery = 7Amps.
So a 125w/ch like the A2125 would be enormous and draw over 83 amps continuous from the battery.
So again pure class A for mobile is a pipe dream in any meaningfull power category.
zed only built the A215 in Los Angeles and in fact was the only amp we built for Akphasonik until the late 90's.
Yeah the Soundstream Class A was just a slightly over biased version of these early Soundstream amps but 100% not a class A amplifier.
Someone take some TIP142/147 and bias them hard using the 0.1 ohm emitter resistors used and see how quickly these TIPs turn to ash.
Always amused me how convinced people are when some company advertises "Class A" and they believe the BS put out by these companies who know less than zero what class A really is.
Finally I have never met Nelson Pass but have the utmost respect for him and the designs he has put out. I have read many articles and interviews about Nelson and have found him to be a modest and humble guy.
Steve Mantz
Zed Audio Corporation
I went through a Nakamichi pa300 for use in the car, was amazed at how much more current it consumed as the bias was turned up a bit, idles at 3 amps now and uses a 12v fan running at 5v to keep it cool and quiet. Was also amazed at how good it sounds
I have had a chunk of time spent awaiting my daughters daily release from school, and it has made for a good time to enjoy some music in a non-moving car.
The sound improved with the replacement of most of the Mylar caps and most of the electrolytic ones also. Source is a modified factory head unit, dedicated power, better decoupling, popular discrete op amps.
I have had a chunk of time spent awaiting my daughters daily release from school, and it has made for a good time to enjoy some music in a non-moving car.
The sound improved with the replacement of most of the Mylar caps and most of the electrolytic ones also. Source is a modified factory head unit, dedicated power, better decoupling, popular discrete op amps.
Nelson Pass Power Amps
Another user who just found this thread - so late to the party. Long time fan of Nelson Pass designs, all the way back to the 1970's. My introduction to high end audio was a Threshold 400. Later owned a pair of 4000 amps, ran them bridged to power Dayton Wright electrostats. That setup required a dedicated 20 amp circuit for each amp. Still later sold one and had Threshold modify one to a stasis design, which I still own.
I have collected, and still run, several Soundstream Reference series amps (Picasso and 10.0). Thought these were Nelson Pass designs. Yes? No? The amps are pretty old by now. I think they are all original inside - they definitely need some attention.
Seems a lot of the posters to this thread are not afraid to pull a cover and actually work on an amp, and that's why I'm posting today. Hope you're still around to read and reply. I have schematics. I don't have the skills to work on a power amp.
So, would someone here be interested in rebuilding a Picasso and a 10.0. Or can you recommend someone with experience with Reference Series amps.
Thanks.
Another user who just found this thread - so late to the party. Long time fan of Nelson Pass designs, all the way back to the 1970's. My introduction to high end audio was a Threshold 400. Later owned a pair of 4000 amps, ran them bridged to power Dayton Wright electrostats. That setup required a dedicated 20 amp circuit for each amp. Still later sold one and had Threshold modify one to a stasis design, which I still own.
I have collected, and still run, several Soundstream Reference series amps (Picasso and 10.0). Thought these were Nelson Pass designs. Yes? No? The amps are pretty old by now. I think they are all original inside - they definitely need some attention.
Seems a lot of the posters to this thread are not afraid to pull a cover and actually work on an amp, and that's why I'm posting today. Hope you're still around to read and reply. I have schematics. I don't have the skills to work on a power amp.
So, would someone here be interested in rebuilding a Picasso and a 10.0. Or can you recommend someone with experience with Reference Series amps.
Thanks.
Try Wade. He did two D100II's for me.. (He worked at SS)
Old School Soundstream Repair
soumdstream old school amplifiers
Hello,
..........
Thanks,
Wade Stewart
8513 Elm Ave
Orangevale, CA
95662
916 294 7967
wade@acelabsaudio.com
.
Old School Soundstream Repair
soumdstream old school amplifiers
Hello,
..........
Thanks,
Wade Stewart
8513 Elm Ave
Orangevale, CA
95662
916 294 7967
wade@acelabsaudio.com
.
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