Thurlby Thandar AC1000A Low Distortion 1kW Power Source | Rapid Online
This is one that comes from a test equipment manufacturer . It looks to be much like the Accuphase and perhaps the older PS ? I am told it is a bit mechanically noisy . Interesting it should exist .
This is one that comes from a test equipment manufacturer . It looks to be much like the Accuphase and perhaps the older PS ? I am told it is a bit mechanically noisy . Interesting it should exist .
From the TT datasheet:
"Because of the large increase in the peak currents that can result from having a pure sinewave maims voltage supply, the AC1000A is also very useful for stress testing a wide variety of power supplies types within electronic equipment."
I think their idea of low cost will be quite different from ours.
"Because of the large increase in the peak currents that can result from having a pure sinewave maims voltage supply, the AC1000A is also very useful for stress testing a wide variety of power supplies types within electronic equipment."
I think their idea of low cost will be quite different from ours.
My advice is this . 80 VA and that's the limit (0.5 deg/watt heat-sink ) . 0.1 % THD . Build it yourself . It will be a handy thing to have and will sometimes do a good job . Above that the Naim Audio advice . It might have variable voltage and Hz . Try having 40 Hz also . It is about the limit of how low you can go . I have doubts about going above 60 Hz . My Garrard PSU's went from 40 to 60 Hz 200 to 253 V. Distortion about 0.05% on the real load . Garrard were designed to work up to 270 VAC ( 135 ) at 50 Hz . I suspect USA users would be better to use 50 Hz . The pulley's were also to a higher standard when 50 Hz as more metal left on the pulley . The 40 Hz comes from an area that had it( I think ICI supplied an area with power from the chemical works , Garrard built to that 40 Hz spec ) . Handy to have that as some 78's are more like 66 RPM . You have to watch out for beat frequencies between incoming and outgoing supplies . For a turntable the higher speeds require more voltage for the same torque when 78 . About 60 to 95 RPM if using 40 to 60 Hz and the tweak control using 50 Hz as the centre frequency .
210 V suits very early Garrard 301's when used with modern pick ups . As a rule these have black tape windings and no green wires ( some are cobbled together from different 301's so hard to always say ) . Early 401's need 246 V ( pop up strobe and 301 flat thrust bearing ) . Most others like 235 V . The motors do get very hot , ventilate them . By a gnats whisker I like 301's about serial number 60 000 best and the later cheap looking strobe 401's ( 16 watt motor not 12 watt ) . TD124 is not as good too me . A Lenco 88 will soon be my home turntable . I will build it a regenerator .
210 V suits very early Garrard 301's when used with modern pick ups . As a rule these have black tape windings and no green wires ( some are cobbled together from different 301's so hard to always say ) . Early 401's need 246 V ( pop up strobe and 301 flat thrust bearing ) . Most others like 235 V . The motors do get very hot , ventilate them . By a gnats whisker I like 301's about serial number 60 000 best and the later cheap looking strobe 401's ( 16 watt motor not 12 watt ) . TD124 is not as good too me . A Lenco 88 will soon be my home turntable . I will build it a regenerator .
I have some experience with turntable drive circuits. I designed the driver circuit for the first and second generation Rockport turntables. It was pretty straightforward. I used a state variable oscillator to get two precisely 90 degree drive signals. These then went to two LM3886 power amps and then transformers. I used current feedback to stabilize everything. Getting .01% THD is not difficult, but the motors internal fields are not perfect and a low output impedance amplifies the motor issues. The current feedback also allows for correction with frequency. The first one provided 33 and 45 (60Hz and 81 Hz) so it was not a big deal. The second version was designed for a library application for transcribing a lot of older recordings including 78's. It was continuously variable from below 30 RPM to 90 RPM with a switchable motor to provide 1/2 speed, which they used for the transfers once they were sure of the original speed. The big frequency range necessitated the drive level compensation. Current drive corrected for it automatically. I also had a start cycle with full power and then dropped the power by approx 1/2 once the platter was spinning. The transfer system had an 80 Lb 18" stainless platter as I remember. With two amps and two transformers driving a motor similar to the old big Papst outer rotor motor, during start is was around 50W and running the whole thing used around 20W. A fun project, no money to speak of and only a few ever made.
Interesting what passes for competence in audio engineering - a friend who I've been visting quite often, seeing how he's progressing in tweaking his gear, is down an amp at the moment. Naim was just mentioned, and he uses a recent Naim integrated and Naim speakers - both are about 5 years old. Capable of very good sound when everything is firing, that integrated is out cold at the moment ...
Reason? The PS smoothing caps have spilt their guts out everywhere, in a slow process, apparently it's a complete mess inside - will take him some time to clean up the crap, hopefully without too much replacement of other parts. Possible culprit? Rails of 38V, caps are marked 40V - I can vouch for the amp not being in a hot environment, etc.
Reason? The PS smoothing caps have spilt their guts out everywhere, in a slow process, apparently it's a complete mess inside - will take him some time to clean up the crap, hopefully without too much replacement of other parts. Possible culprit? Rails of 38V, caps are marked 40V - I can vouch for the amp not being in a hot environment, etc.
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Its a Naim, what did you expect , budget built hi-fi and i emphasize budget ....
??? Could you please elaborate a bit? Why is that "a Scottish" thing?
"Budget"? Wayne, I don't know when you looked last, but in Europe, they are hardly cheap.
Obviously, it will heavily depend on what one calls budget. For me, budget is a cheap, God knows whose but probably Chinese, amp costing like $200-350, and promising "High End" performance in pidgeon English.
But once you are over $1k per uniot for your cheapest, entry level product, you are no longer cheap. Not exorbitant, but no longer cheap.
And by then, they do face some tough competition, now that the mass producers, like Yamaha, Pioneer, Marantz, etc have started launching models costing $3k and above.
I did struggle to go below 0.05% . The load seems to be the problem . I suspect I was measuring distortion of the output and load combined . That is an output impedance exacerbated by the output transformer caused the regenerator to correct what it saw which was a composite . Hence saying a direct coupled bridge at 360 VDC . It is just possible that a composite is no bad thing ? With a motor there is no difficult choice . The vibration is less or it isn't . Voltage and distortion are the key factors if a hysteresis motor . Low distortion allows a higher voltage and sounds better . With belt drive the effects are very subtle . Voltage is the main thing and motor size . I dislike belt drives as no amount of PSU sophistication brings about a big change . This suggests to me a belt is a device for a middle grade turntable . A stiff belt is better . My criticism is most turntables kept faith with the AR turntable . It was a cunning cheap device . It is not a broadcast quality turntable although serviceable as a stand in .
A further piece of evidence . If a steeper motor ( 7.5 deg ) is connected to another motor it's output can be measured into a resistor . It will be a strange looking sine wave of about 10 % THD . A top grade turntable synchronous will be identical . This causes me to speculate that early steppers were just redesigned synchronous . Take them apart and all the pieces look alike .
If a synchronous is driven by a direct coupled PSU the waveform drops to 0.01% if that's where we are . Insert a small resistance , then measure again . With very little resistor help the motor is back at 10 % THD . Logically this must be true as the alternator output should be identical .
With very little trouble I can get a synchronous to run at 10% THD if mains or regenerator . That involves a tiny bit of passive filtering when mains . The question then is how much voltage . Motors can be combined to phase cancel vibration . I don't think I ever saw motors vertically stacked ?
Hysteresis motors are different and will respond better . They are reasonably synchronous which helps . I suspect Paspt might be a hysteresis type . They hate DC .
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A bit of a silly problem . My old Quad 33 / 303 used for the TV has a small background hum . As my job is 90% sorting out hums like this I should correct it . About - 80 dB .
Recently the Play Station has joined it ( not mine although useful for internet ) . The hum levels subtly higher . It turns out not to be the Play Station .
At first it seemed an obvious hum loop . Drawing it on paper says not very likely . Down the pub the switch-mode in some device acting as an AM transmitter gets mentioned . This had occurred to me . Yes there was a little of something there on my old oscilloscope ( must buy a laptop so as to use a modern one , I have that on my main computer ) .
Many filters built and no result . The connection of just the RCA ground enough to cause the problem .
Then a leap in the dark . 470 pF NPO ceramic put in the TV aerial centre . Cured . Even though the aerial amplifier is fed by a high grade transformer and big cap then a conventional voltage regulator this is the source of the hum ( isolated transformer with chassis ground , no 0 volt to ground ) . I didn't calculate the 470 pF , it seemed about right as a first attempt .
Isn't life strange . A modern amp had no problem . This is no mystery , but not expected .
The Quad is to book spec with 3 minor modes . Tape input set high for CD . Separate output caps for tweeters . PSU bypass caps . The bias is set by fixed resistors and DC at centre voltage likewise . Always check DC . It can be very low or high and still work albeit badly . It should be 67 V . With modern speakers the 303 is sometimes exactly the right sound . In it's day perhaps it found fewer good matches . I never get listening fatigue when it is used . I keep it for sentimental reasons . These days I just trust it to be honest when comparing . Even the phono side which is nothing special is good enough to say why I like LP's . The FM 3 still a first class tuner . Detail is excellent . Friends who own " better " sometimes are unable to understand why it sounds so good . Cables are all home made and sensible .
I wonder if car designers have a Traction Avant in the garage to keep them honest ? They should . Mine would be a Slough made one with DS suspension ( the last ones made in UK ) .
I put together a Hypex amp recently . I suspect I found it's sweet spot by getting the gain just right and building a nice PSU . Mostly I prefer the Quad . It is hard to say either is better . They seem very similar . Using the Hypex SMPS made them less similar . I would say although perfectly pleasant the SMPS sounds brighter in a way that seems less accurate . I would liken it to how a ribbon mike sounds which is fine if a ribbon mike . The conventional PSU has to be very large to compete . To my great regret I found I liked the Hypex . I was determined not to .
Recently the Play Station has joined it ( not mine although useful for internet ) . The hum levels subtly higher . It turns out not to be the Play Station .
At first it seemed an obvious hum loop . Drawing it on paper says not very likely . Down the pub the switch-mode in some device acting as an AM transmitter gets mentioned . This had occurred to me . Yes there was a little of something there on my old oscilloscope ( must buy a laptop so as to use a modern one , I have that on my main computer ) .
Many filters built and no result . The connection of just the RCA ground enough to cause the problem .
Then a leap in the dark . 470 pF NPO ceramic put in the TV aerial centre . Cured . Even though the aerial amplifier is fed by a high grade transformer and big cap then a conventional voltage regulator this is the source of the hum ( isolated transformer with chassis ground , no 0 volt to ground ) . I didn't calculate the 470 pF , it seemed about right as a first attempt .
Isn't life strange . A modern amp had no problem . This is no mystery , but not expected .
The Quad is to book spec with 3 minor modes . Tape input set high for CD . Separate output caps for tweeters . PSU bypass caps . The bias is set by fixed resistors and DC at centre voltage likewise . Always check DC . It can be very low or high and still work albeit badly . It should be 67 V . With modern speakers the 303 is sometimes exactly the right sound . In it's day perhaps it found fewer good matches . I never get listening fatigue when it is used . I keep it for sentimental reasons . These days I just trust it to be honest when comparing . Even the phono side which is nothing special is good enough to say why I like LP's . The FM 3 still a first class tuner . Detail is excellent . Friends who own " better " sometimes are unable to understand why it sounds so good . Cables are all home made and sensible .
I wonder if car designers have a Traction Avant in the garage to keep them honest ? They should . Mine would be a Slough made one with DS suspension ( the last ones made in UK ) .
I put together a Hypex amp recently . I suspect I found it's sweet spot by getting the gain just right and building a nice PSU . Mostly I prefer the Quad . It is hard to say either is better . They seem very similar . Using the Hypex SMPS made them less similar . I would say although perfectly pleasant the SMPS sounds brighter in a way that seems less accurate . I would liken it to how a ribbon mike sounds which is fine if a ribbon mike . The conventional PSU has to be very large to compete . To my great regret I found I liked the Hypex . I was determined not to .
Scotts Are Blowhards....
Scotts are world renowned for being niggards (stingy, miserly.....IOW tight arsed to the extreme).
Running 40V caps at 38V is begging for future warranty claim and reputation trouble, and for the saving of not very much additional BOM cost.
Naim gear has never impressed me for build quality, nor sound quality.
Dan.
LOL.
Scotts are world renowned for being niggards (stingy, miserly.....IOW tight arsed to the extreme).
Running 40V caps at 38V is begging for future warranty claim and reputation trouble, and for the saving of not very much additional BOM cost.
Naim gear has never impressed me for build quality, nor sound quality.
Dan.
Musical Fidelity were the masters of running capacitors ABOVE rated voltage
Max, each and every country has a part of it with such a reputation. My own country is no exception. So I know what you refer to.
On the plus side, the Scotts are very likeable people on the whole, and as I have tasted, extremely hospitable. I have tremednously enjoyed my visit to Edinburgh in 2009, definitely one of the best trips of my life.
I was a bit surprised when our host greeted us at his home, took us in, offered us a drink in form of Scotch, opened a brand new bottle and threw the cork away. He explained that was their traditional way of saying there's no leaving while there's a drop left in the bottle. Unfortunately, totally wasted on me, I don't drink at all, and the only Scotch even I can actually recognize and even enjoy once a year is Grant's whiskey.
We (wife and I) came prepared, so we retaliated with a bottle of Serbian made plum brandy, sliwovitz (literal translation: plum drink), but strongly advised against opening it up at all at that time, let alone throwing the cork out.
That aside, I am not at all sure Naim is a Scottish company, as is say Linn. As a matter of fact, I believe Naim is located somewhere in souther England.
As for Naim's sound, agreed, I also am not impressed, but I do note that they seem to have a very partisan following.
Of all UK audio companies, Armstrong was "my" company, they never failed me. And neither did Boothroyd-Stuart Meridian, either as Lecson, or as Meridian. And of course, there's always dCS, but they are not of this planet, as witnessed by their cosmic prices.
On the plus side, the Scotts are very likeable people on the whole, and as I have tasted, extremely hospitable. I have tremednously enjoyed my visit to Edinburgh in 2009, definitely one of the best trips of my life.
I was a bit surprised when our host greeted us at his home, took us in, offered us a drink in form of Scotch, opened a brand new bottle and threw the cork away. He explained that was their traditional way of saying there's no leaving while there's a drop left in the bottle. Unfortunately, totally wasted on me, I don't drink at all, and the only Scotch even I can actually recognize and even enjoy once a year is Grant's whiskey.
We (wife and I) came prepared, so we retaliated with a bottle of Serbian made plum brandy, sliwovitz (literal translation: plum drink), but strongly advised against opening it up at all at that time, let alone throwing the cork out.
That aside, I am not at all sure Naim is a Scottish company, as is say Linn. As a matter of fact, I believe Naim is located somewhere in souther England.
As for Naim's sound, agreed, I also am not impressed, but I do note that they seem to have a very partisan following.
Of all UK audio companies, Armstrong was "my" company, they never failed me. And neither did Boothroyd-Stuart Meridian, either as Lecson, or as Meridian. And of course, there's always dCS, but they are not of this planet, as witnessed by their cosmic prices.
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