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Linn Lingo schematic
Linn Lingo schematic
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Old 28th January 2019, 09:21 AM   #21
cakyol is offline cakyol  United States
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In the interest of not overloading the max voltage capacity of the transistors (and other components), would it be ok to convert the 120V US supply to about 190 volts thru a transformer and use the 240 V setting of the Valhalla ? So it would be as if the Valhalla is connected to a 190 Volt instead of 240. This would still give full wave rectification and would produce 1.41 x 190 = 270 Volts (not as hi as the 320 as is the case with the full 240V UK supply). Would the circuit continue working but at much LESS stress levels ?

I am thinking of having a custom transformer made with 120/240 Volt primary and 190 Volt secondary at about 25-30VA for this purpose

Thanks
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Old 28th January 2019, 11:09 AM   #22
nigel pearson is offline nigel pearson  United Kingdom
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I just built the circuit using ex Linn parts I didn't throw away. There isn't a big difference in ripple when USA voltage. A well designed circuit. What is different is DC voltages. 230 VAC ( UK ) is 311VDC. 115 VAC ( US ) is 292 VDC. That further suggests 85V rms RED phase to be about right. I used 2 x 4K7 7 W and 1 x 680R 3 watt ( 22V to measure ). Circuits as above. 9.3V pk to pk ripple. It should be 2 V pk to pk 220 uF. My test suggest lower as ripple becomes more sinusoidal.

As I was using a variac I took the voltages up very slowly to reform the capacitors. All gave > 47 uF. USA gets a small advantage using 60Hz. Made on a piece of wood and using brass woodscrews.

My feeling is 47 uF is just the wrong side of correct. Linn told me they only realised when trying 45 RPM and saw what we saw on my graphs. Usually it was hidden in the UK. Beat frequencies between real 50 Hz and mains took place. It is possible the USA is better off with 50/60 Hz. Linn said Lingo is class A. They assumed Valhalla class AB. As far as I know it's not and has 5 watts static dissipation. As the motor is less than 1 watt that should be class A. It runs 24/7 I think.

All in all Valhalla is a well designed unit which really required 100 uF minimum. Ultra reliable. It's usually justs the rectifier and R1 that go and the caps in time. The standard of the better TV circuits. I was dissapointed with my Lingo. I liked my improved Valhalla more. The 66 VAC of my Lingo being more detailed at the cost of pace. I suspect an improved Valhalla and a Lingo both at 75 VAC would be very alike. Doubtless the Lingo will do - 80dB. I have no idea if that is important.
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Old 28th January 2019, 11:27 AM   #23
nigel pearson is offline nigel pearson  United Kingdom
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Quote:
Originally Posted by cakyol View Post
In the interest of not overloading the max voltage capacity of the transistors (and other components), would it be ok to convert the 120V US supply to about 190 volts thru a transformer and use the 240 V setting of the Valhalla ? So it would be as if the Valhalla is connected to a 190 Volt instead of 240. This would still give full wave rectification and would produce 1.41 x 190 = 270 Volts (not as hi as the 320 as is the case with the full 240V UK supply). Would the circuit continue working but at much LESS stress levels ?

I am thinking of having a custom transformer made with 120/240 Volt primary and 190 Volt secondary at about 25-30VA for this purpose

Thanks
You will most likely clip the output wave. That should be heard in the motor as chatter. If it's run this long it should continue OK.

What you could try is a lamp in series with live in ( or neutral ). Try a 40 watt one first. Old type not LED or whatever. Look to drop 5 VAC or 10. You should see it go brighter on start. As Valhalla is always on it's only when starting from unpluged we see this. Old TV repairmans trick as current limiter. That should be best of all ideas.

This is the cheaper idea I found. I think they do 0-115 0-115 to 0-55 0-55 also. That way many options are possible.

Vigortronix VTX-146-050-155 Toroidal Transformer 230V Single Primary 50VA 0-55V | Rapid Online
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Old 29th January 2019, 10:24 AM   #24
nigel pearson is offline nigel pearson  United Kingdom
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I just looked again at the Lingo circuit again. The designer obviously was making it complex for the sake of it. I don't understand using a simple transistor cyrystal oscillator when a 4060 does it better. Maybe he thought the 4060 was about to die. The output stage is very like the Valhalla which is ironic as Linn were convinced the two were very different. The Lingo uses TL074 in place of LM324N quad op amp. The filter looks to be similar to Ti Filter Pro solution ( was freeware and maybe still is ). If LM324N is used at low current it can give good results. 1mA perhaps. It has many virtues in near rail to rail use and seems to be based on a comparator ( LM339? + class AB stage ). I suspect if +/- DC rail version of the Valhalla could be built it would be better. Easy to say, harder to do. A State Variable Filer oscillator could be better. A simple strobe to set the speed. 33 1/3 - 45 would could 2 pence and a switch if so. ESP Audio show how that's done. The TD125 of which the LP12 is a cousin had the Wien variant of that and lamp stabilisier. Reading the TD125 review got me into hi fi. If Linn requested a 6 V version of their motor from Airpax it would have been better. It wouldn't be hard to hand wind that. The motor is very simple inside.

To restate the tests of yesterday. The main disadvantage of the 115V Valhalla is lower DC voltages ( Circa 311 VDC and 292 VDC at 230/115 VAC ). If looking to use 100 VAC output at 45 RPM that should be factored in ( I assume a high degree of understanding to even think of it ). I would take the output to be 90% at best VDC/2 x 0.7071. That says 90 Vrms for 115 Vrms mains. A 10 VAC ( rms ) boost transformer to give 125 VAC is the limit ( my house is 246 VDC ). My best advice is 85 VAC 33 1/3- 45. My load was 10 K 80 ( 2 x 4K7 7W and 680R 3 watt to measure ). Ripple was 9.3 V peak to peak 2 x 47 uF. It is hard to say how my test meter reacts to that much ripple. All the same it was the same test each time. I infer the 220 uF version is 2 V pk to pk. That is a 13.4 dB upgrade which seems to be seem on tests. As the motor itself the major distortion ( current waveform about 10 % THD, I have a graph if asked ) -60 dB seems a good result. The very low output impedance of Valhalla might say the current waveform is being controlled.

This all came about because my Valhalla went wrong. I had sold my first production Lingo to raise cash. It seemed daft not to find out the truth. I was told another Scotish company used the same contractor to make this circuit. I suspect like an engine management device it wasn't really understood. I have a lot of respect for Valhalla's designer. Within a tight budget it has no major defect. The one is has if any is easy to put right. If it had been a +/- voltage rail design 47 uF would have been enough as it seems to be a common mode error.

http://www.ti.com/tool/filterpro&DCM...e+OT+filterpro
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Old 29th January 2019, 12:31 PM   #25
postpunk is online now postpunk  Germany
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I Don’t have an oscilloscope, so I have to rely on the facts provided by Nigel. That being said, my ears are telling me that putting in larger caps is worth it. Fitting the caps offboard is necessary because of lack of space. I let them dangle on short pieces of wire and made extensive use of shrink tubing and electrical tape.
Still, I would like a Lingo to compare with. I might be able to get one for a good price, we will see.

I am getting a sort of thumping ticking noise picked up my the phono leads. Getting rid of that is now my number one priority. Some sort of a shielding sock, perhaps. Putting preamp and turntable elsewhere is not an option.
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Old 29th January 2019, 03:47 PM   #26
postpunk is online now postpunk  Germany
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Oh, after a more extended evaluation I must say that it is clearly better now. Putting my ear to the top plate reveals that the motor is quieter now even though the voltage is set higher than it previously was.
Thanks Nigel! Also thanks for going through the circuits, very interesting!
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Old 30th January 2019, 08:08 AM   #27
postpunk is online now postpunk  Germany
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Quote:
Originally Posted by postpunk View Post
Oh, after a more extended evaluation I must say that it is clearly better now. Putting my ear to the top plate reveals that the motor is quieter now even though the voltage is set higher than it previously was.
Thanks Nigel! Also thanks for going through the circuits, very interesting!
Probably entirely unrelated to the mods, I am now hearing motor chatter. I guess that means that the amplifier is clipping. DC is also too high. Tried with another motor and it's the same. A kind of tock tock tick noise. I get that from time to time. Any idea what might be the cause?
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Old 30th January 2019, 12:05 PM   #28
postpunk is online now postpunk  Germany
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Never mind, I reversed my isolation transformer to drop 20V. Everything seems fine now. The mains here are at 247 V in the night. My isolation transformer on top of that seems to have pushed it over the edge.
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Old 6th February 2019, 07:38 AM   #29
postpunk is online now postpunk  Germany
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I have gone for the full hog, 45rpm mod. It works very well. I am using relays to switch crystals and phase shift capacitor. The crystals are not spot on, with the 45rpm one giving 65,7 Hz and the 33rpm 49,8 Hz.
Is there any point in buying say ten of each to try finding slightly slower and faster ones? I guess that there are some tolerances?
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Old 7th February 2019, 07:50 PM   #30
cakyol is offline cakyol  United States
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Has anyone generated a low voltage (24 volt) using the Valhalla board ? I am thinking of exchanging the 110 volt premotec/airpax Linn motor with a 24 volt Hurst motor. If I can generate 20 - 24 volts from the Valhalla, I cn drive the Hurst motor. Since it is of lower voltage, it is bound to be a bit less noisy.

Has anyone tried adjusting the Valhalla board to a LOWER voltage ?

Thanks
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