DB Drive WDX3K has a nasty turn on pop. And a slight turn off pop. When amp came in, it had shorted outputs, damaged drivers. The gain was full blast and the lpf was all the way down, lol. Not sure if the cranked gain might have damaged something else.. it's running fine aside from the turn on/off pop. is there something I can do to make it fix the problem or make it better? Owner said it did it before the repair... but ya... it's a nasty startup pop.
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DB Drive WDX3k
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Hi New
I'm new but I have read the odd post on here over the years. I've never built an amp though that looks like fun. For now I want to learn how to fix amps. I don't like most modern amps. They seem to be becoming progressively underpowered?
I currently own an Arcam Alpha 8, 2 x Technics 900Mk2, and a NAD C370. The first three (the Arcam and both Technics) still work as perfect as the day I bought them. I notice they both use Jap caps everywhere i.e. Rubycon, Panasnoic, Elna. The NAD C370 is currently dead and most of the caps appear bad and so I might ask the odd question when I start to try and fix it. It's caps are erm.. not Japanese.
Anyway, hello from England.
I currently own an Arcam Alpha 8, 2 x Technics 900Mk2, and a NAD C370. The first three (the Arcam and both Technics) still work as perfect as the day I bought them. I notice they both use Jap caps everywhere i.e. Rubycon, Panasnoic, Elna. The NAD C370 is currently dead and most of the caps appear bad and so I might ask the odd question when I start to try and fix it. It's caps are erm.. not Japanese.
Anyway, hello from England.
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Alternative to Onkyo SE-200 PCI
I sold my old Onkyo card and looking something similar for good sound with the PC.
Can someone please recommend me some internal and external sound card?
Thanks
Can someone please recommend me some internal and external sound card?
Thanks
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OB FAST with 3.5in Fullrange and SB23NRXS45-8
This thread is a spin-off from the 10F/8424 / RS225-8 FAST speaker thread here:
https://www.diyaudio.com/forums/full...st5893670.html
![Click the image to open in full size.]()
I had some extra baffles made up when I had the 10F/RS225 cabinets made. I had bought the SB23NRXS45-8's a long time ago, meaning to try them in the sealed box FAST with a 3.5in fullrange in a separate Dagger chamber. The RS225 setup with the 10F sounds so good, I never got around to trying the other woofer. Until today that is. I decided to just put it all together and listen it in the open as an OB to save time since I did not want to remove the baffle from the other speaker. Using the same passive 1st order transient perfect XO, I connected it all up. Added some aluminum MakerBeam supports held together with 3M Bluetape and plugged it into my amp and had a listen. Not expecting much, but instead - I was blown away by the sound quality. The dynamics, clarity and ease of presentation. The bass was less than a sealed speaker of course, but it wasn't bad. A subwoofer would handle the transition very nicely. This is a very narrow 10in wide baffle. Something a little bigger or even something with some fold back wings would improve bass a lot.
It sounded so good, I knew it was special and deserves its own thread as an OB. Although I am using a PS95-8 for the fullrange, any 8ohm 2.5in to 3.5in fullrange would work here: TC9FD, TG9FD, 10F/8424, B80, 3FE25, 3FE22, FF85WK, P839086, etc. I happen to be listening to it first with the PS95-8 and the sound is wonderful.
I think a lot of the quality comes from a good smooth shallow first order XO that allows a broad range of the wonderful SB23's qualities to come through. The SB23 is a papercone woofer vs the RS225's aluminum cone. They have a different sound. Both are great - but different.
I just wanted to bring attention to the fact that this speaker (or even the 10F/8424 and RS225) and its progenitor, can simply be stripped of the rear chamber and made into a compact OB. In some situations like an aprtment with close by neighbors, you may actually want less powerful bass. But the rest of the music can still sound superb.
![Click the image to open in full size.]()
![Click the image to open in full size.]()
XO being used is same as one for 10F/RS225:
![Click the image to open in full size.]()
https://www.diyaudio.com/forums/full...st5893670.html
I had some extra baffles made up when I had the 10F/RS225 cabinets made. I had bought the SB23NRXS45-8's a long time ago, meaning to try them in the sealed box FAST with a 3.5in fullrange in a separate Dagger chamber. The RS225 setup with the 10F sounds so good, I never got around to trying the other woofer. Until today that is. I decided to just put it all together and listen it in the open as an OB to save time since I did not want to remove the baffle from the other speaker. Using the same passive 1st order transient perfect XO, I connected it all up. Added some aluminum MakerBeam supports held together with 3M Bluetape and plugged it into my amp and had a listen. Not expecting much, but instead - I was blown away by the sound quality. The dynamics, clarity and ease of presentation. The bass was less than a sealed speaker of course, but it wasn't bad. A subwoofer would handle the transition very nicely. This is a very narrow 10in wide baffle. Something a little bigger or even something with some fold back wings would improve bass a lot.
It sounded so good, I knew it was special and deserves its own thread as an OB. Although I am using a PS95-8 for the fullrange, any 8ohm 2.5in to 3.5in fullrange would work here: TC9FD, TG9FD, 10F/8424, B80, 3FE25, 3FE22, FF85WK, P839086, etc. I happen to be listening to it first with the PS95-8 and the sound is wonderful.
I think a lot of the quality comes from a good smooth shallow first order XO that allows a broad range of the wonderful SB23's qualities to come through. The SB23 is a papercone woofer vs the RS225's aluminum cone. They have a different sound. Both are great - but different.
I just wanted to bring attention to the fact that this speaker (or even the 10F/8424 and RS225) and its progenitor, can simply be stripped of the rear chamber and made into a compact OB. In some situations like an aprtment with close by neighbors, you may actually want less powerful bass. But the rest of the music can still sound superb.
XO being used is same as one for 10F/RS225:
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Nedded PC freq analizer for Tape speed adjustment
I have ahunch after listening a cassette recorded on my KX-670 that the speed is too low since on other decks the recording was a little but not shure, fast. I will get a cassete recorded of a CD with a 3khz tone. That tone I want to feed in my mic imput of the laptop and see it on a freq analizer. I do not knot any especially free software for that. please offer some guidance if at hand. Thanx!
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When is a millimetre not a millimetre ?
Bought some 5mm pitch caps off Ali-Express.
When they came they were 7.5mm.
So fit them best I could.
On my next pcb buy I made all the caps 7.5mm pitch holes.
Then I ran out so I purchased some more 7.5mm pitch caps.
When they came they were 10mm pitch FFS.
Don't they have rulers in China ?
When they came they were 7.5mm.
So fit them best I could.
On my next pcb buy I made all the caps 7.5mm pitch holes.
Then I ran out so I purchased some more 7.5mm pitch caps.
When they came they were 10mm pitch FFS.
Don't they have rulers in China ?
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We need a DIY Audio Club in the Los Angeles area
Would like to form a DIY audio club in the Los Angeles area and particularly centered in the Conejo and San Fernando Valleys.
The very large, 2100 member Los Angeles and Orange County Audio Society has absolutely no interest in DIY. Ive already talked to them about it. All they care about is very expensive audiophile gear. The more expensive the better. Huge snob appeal factor rather than actual performance concerns.
Im willing to handle most of the organization effort if there is some interest.
The very large, 2100 member Los Angeles and Orange County Audio Society has absolutely no interest in DIY. Ive already talked to them about it. All they care about is very expensive audiophile gear. The more expensive the better. Huge snob appeal factor rather than actual performance concerns.
Im willing to handle most of the organization effort if there is some interest.
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WTB: Pure Audio Project Neo 15" woofers (looking for 4)
Just like the title says
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Did my JBL2445 drives fail or not? If yes, how?
I have a problem. The FR of my drivers (both) has changed. I checked everything, even the UMIK, but it really seems something happened to the drivers.
The FR plot in blue shows normal (before, with XO) and the red the current state (without XO).
In the impedance plots, the black one was taken at the same time as the normal FR at the right driver using headphone output and a 100 ohm sensing resistor.
The red trace is the current imp curve taken with the same equipment, the yellow one is the left driver.
The funny thing is, both drivers behave very similar (the FR is same). I measured the right driver a lot and I might have sent too low frequency to it - but definitely less than one watt, it must have been more likely around 100 mW maximum. The other thing is, the drivers are connected to a SE tube amp - directly to the 8 ohm tap with active XO. Maybe the damage comes from there somehow?
I could understand a failure of the right driver - that one was definitely under some LF stress - but at a very low volume. But not an identical failure on both at the same time.
The question is, have you ever seen anything similar? What is the cause? Can it be fixed without replacing the diaphragm? How to prevent this in future? Could the diaphragm crack? The drivers are old, so it could be a failure due to age?
The FR plot in blue shows normal (before, with XO) and the red the current state (without XO).
In the impedance plots, the black one was taken at the same time as the normal FR at the right driver using headphone output and a 100 ohm sensing resistor.
The red trace is the current imp curve taken with the same equipment, the yellow one is the left driver.
The funny thing is, both drivers behave very similar (the FR is same). I measured the right driver a lot and I might have sent too low frequency to it - but definitely less than one watt, it must have been more likely around 100 mW maximum. The other thing is, the drivers are connected to a SE tube amp - directly to the 8 ohm tap with active XO. Maybe the damage comes from there somehow?
I could understand a failure of the right driver - that one was definitely under some LF stress - but at a very low volume. But not an identical failure on both at the same time.
The question is, have you ever seen anything similar? What is the cause? Can it be fixed without replacing the diaphragm? How to prevent this in future? Could the diaphragm crack? The drivers are old, so it could be a failure due to age?
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Son of Zen Amp
Hello Gents,
What is the power draw for a Son of Zen, 3.5w @ 4 to 8 ohms ?
cheers, it's Friday !
What is the power draw for a Son of Zen, 3.5w @ 4 to 8 ohms ?
cheers, it's Friday !
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Push-Pull VAS
Hello, I'm a beginner (kinda) and have been interested in symmetric input and amplification stages for some time.
After reading the The push-pull VAS section on D.Self's book, I tried replicating his design (the one which combines input stage current mirrors with the push-pull vas) on LTSpice and indeed encountered the issues he described (mainly the impossibility of setting the VAS current as it settles by itself at some microamps).
The other issues were: excessive dissipation at the beta-enhance emitter-follower and oscillations due to the lack of current in the VAS (especially if I put a cap across the VBE multiplier).
So I tried a method of forcefully setting the VAS current:
I'll be absolutely honest here: I pulled this circuit out of my ***, but the simulation didn't give me such bad results, so I wanted to know if I should even waste my time prototyping it despite its weirdness. (also because prototyping it will take a loooong time)
I'm attaching the phase/gain plots, THD measurements and a description, as well as a PDF schematic so you can see the components more clearly. I'm also attaching the .asc file.
I plan to use the same components simulated here except:
![Click the image to open in full size.]()
![Click the image to open in full size.]()
![Click the image to open in full size.]()
![Click the image to open in full size.]()
Thank you very much.
After reading the The push-pull VAS section on D.Self's book, I tried replicating his design (the one which combines input stage current mirrors with the push-pull vas) on LTSpice and indeed encountered the issues he described (mainly the impossibility of setting the VAS current as it settles by itself at some microamps).
The other issues were: excessive dissipation at the beta-enhance emitter-follower and oscillations due to the lack of current in the VAS (especially if I put a cap across the VBE multiplier).
So I tried a method of forcefully setting the VAS current:
- Driving the base of a current mirror with the signal from the input stage
- Using the transistor not responsible for setting the mirror current as the beta-enhance EF
- And finally, using the voltage across the EF resistor (which is under a constant current) to set the VAS current
I'll be absolutely honest here: I pulled this circuit out of my ***, but the simulation didn't give me such bad results, so I wanted to know if I should even waste my time prototyping it despite its weirdness. (also because prototyping it will take a loooong time)
I'm attaching the phase/gain plots, THD measurements and a description, as well as a PDF schematic so you can see the components more clearly. I'm also attaching the .asc file.
I plan to use the same components simulated here except:
- VBE multiplier: I'll use a 2SC3807 instead of the BD139
- Pre-drivers: I'll use a 2SC3423/2SA1360 instead of the BD139/BD140
- Drivers: I'll use a 2SC5171/2SA1930 instead of the BD139/BD140
Thank you very much.
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Most efficient pair of subs in 6CF on 1000W?
First, the setup:
- Two Alpine SWR-1243Ds in 6 cubic feet tuned to 37Hz.
- Alpine PDX-M12 amplifier (1200W RMS at regulated between 2 or 4 ohms)
I do realize that the enclosure is quite over-sized by a factor of two (Alpine recommends 1.5CF per subwoofer). As a result, there is a significant boost in bass in the 35Hz-45Hz that I'm pretty happy with but I am now wondering if there is something else out there with a bit better bandwith while retaining this feature.
Given the power I'm sending, I don't even think I'm using the Alpines to their full extend as the port loads the woofers down and excursion never exceeds ~14mm until 30Hz (the Type R's are Klippel verified at ±20mm xmax and 70mm p-p before damage). Since I already have quite a large box, I was wondering if there is another 12" woofer that is has a lower Q resonance and generous enough travel to get more output out of the large enclosure.
One woofer that piqued my interest is the Eminence LAB12C which appears to be 3dB louder in sensitivity and has a 3x higher compliance (130L vs Alpines 43L).
I realized that I'm not really that interested in sub bass <35Hz but rather would like to hit 35-70Hz more loudly while keeping power the same (~1000-1200W).
The other thing I'm wondering is if I'm somehow downgrading in SQ or durability as the LAB12C looks like a very old-school, albeit industrial design (no shorting rings, no woven tinsel leads, foam surround, etc...). On the other hand, it is very similar to an old-school Adire Audio Shiva I used to run 15 years ago which got down very hard on just 300W.
As a side note, and a little off topic in terms of my design objective, I also have a pair of DC Audio XL 12s that I picked up last year (for a potential project if I decided to go with a huge electrical system to back up sufficient amplification). These things are 60lb a piece, 3" 2200W RMS coils, rated at 87dB. This is something I can also run but am I correct in saying that their benefits will not be realized compared to the Type R's or LAB12s on 1000W?
Any opinions on the Alpine Type R, LAB12C, or using a grossly overmotored subwoofer such as the DC XL 12 on low power. I understand that the QTS will drop when large-signal is applied so it may not be as peaky as the graph indicates. Also inductance on the XL is a whopping 5mH compared to 2mH and 1mH for the Alpine and LAB12, respectively and I know that WinISD does not model this at all.
I've attached a WinISD graph showing the three woofers in the 6CF box tuned to 37Hz on 1000W.
-Green curve = Eminence LAB 12
-Red curve = Alpine SWR-1243D
-Yellow curve = DC Audio XL m2 12
![Click the image to open in full size.]()
Thanks for any advice.
- Two Alpine SWR-1243Ds in 6 cubic feet tuned to 37Hz.
- Alpine PDX-M12 amplifier (1200W RMS at regulated between 2 or 4 ohms)
I do realize that the enclosure is quite over-sized by a factor of two (Alpine recommends 1.5CF per subwoofer). As a result, there is a significant boost in bass in the 35Hz-45Hz that I'm pretty happy with but I am now wondering if there is something else out there with a bit better bandwith while retaining this feature.
Given the power I'm sending, I don't even think I'm using the Alpines to their full extend as the port loads the woofers down and excursion never exceeds ~14mm until 30Hz (the Type R's are Klippel verified at ±20mm xmax and 70mm p-p before damage). Since I already have quite a large box, I was wondering if there is another 12" woofer that is has a lower Q resonance and generous enough travel to get more output out of the large enclosure.
One woofer that piqued my interest is the Eminence LAB12C which appears to be 3dB louder in sensitivity and has a 3x higher compliance (130L vs Alpines 43L).
I realized that I'm not really that interested in sub bass <35Hz but rather would like to hit 35-70Hz more loudly while keeping power the same (~1000-1200W).
The other thing I'm wondering is if I'm somehow downgrading in SQ or durability as the LAB12C looks like a very old-school, albeit industrial design (no shorting rings, no woven tinsel leads, foam surround, etc...). On the other hand, it is very similar to an old-school Adire Audio Shiva I used to run 15 years ago which got down very hard on just 300W.
As a side note, and a little off topic in terms of my design objective, I also have a pair of DC Audio XL 12s that I picked up last year (for a potential project if I decided to go with a huge electrical system to back up sufficient amplification). These things are 60lb a piece, 3" 2200W RMS coils, rated at 87dB. This is something I can also run but am I correct in saying that their benefits will not be realized compared to the Type R's or LAB12s on 1000W?
Any opinions on the Alpine Type R, LAB12C, or using a grossly overmotored subwoofer such as the DC XL 12 on low power. I understand that the QTS will drop when large-signal is applied so it may not be as peaky as the graph indicates. Also inductance on the XL is a whopping 5mH compared to 2mH and 1mH for the Alpine and LAB12, respectively and I know that WinISD does not model this at all.
I've attached a WinISD graph showing the three woofers in the 6CF box tuned to 37Hz on 1000W.
-Green curve = Eminence LAB 12
-Red curve = Alpine SWR-1243D
-Yellow curve = DC Audio XL m2 12
Thanks for any advice.
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NFG here ; what the numbers mean?
Lets start with the sensitivity or could it be efficiency then bandwidth, whats normal and whats the top end units have? Impedance, why 4 ohm or 8 ohm, where is the performance and the reasons for the difference? Where might Ifind a thread explaining all this stuff? Thanks
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Revox B795 hall sensors - Siemens SBV566?
Hi, I need a pair of hall sensors for a revox B795, can someone help please? I have read that the Siemens SBV566 may be a good replacement.
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TAD 2-way in slim enclosure
Hi there,
I am looking to build a 2-way system with TL-1601a and TD-2001.
My problem is that I do not have room for a wide baffle (like TAD 2402 for example) and would like to build a slimmer and taller enclosure.
What is your experience with this assuming crossover with 12dB at around 800 Hz? Will I get problems without baffle step correction?
I am looking at 140 liter internal volume with bass reflex using a Klangfilm Eurodyn horn for the TD-2001.
Inputs or images of similar projects would be very helpful.
Thanks :)
Br Jesper
I am looking to build a 2-way system with TL-1601a and TD-2001.
My problem is that I do not have room for a wide baffle (like TAD 2402 for example) and would like to build a slimmer and taller enclosure.
What is your experience with this assuming crossover with 12dB at around 800 Hz? Will I get problems without baffle step correction?
I am looking at 140 liter internal volume with bass reflex using a Klangfilm Eurodyn horn for the TD-2001.
Inputs or images of similar projects would be very helpful.
Thanks :)
Br Jesper
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Matching BJT transistors help
Hi here.
I know it's the wrong place, but i also know that we sometimes need matched transistors for our beloved Pass amp.
Well, long story short; i need to match two "complimentary" transistors, excatly BCP53T which is PNP / https://assets.nexperia.com/document...BCP53T_SER.pdf with an BCP56T (NPN) https://assets.nexperia.com/document...BCP56T_SER.pdf
I need to match T8A with T9A and T8B with T9B on the attached schem.
The thing i build is an class-A outputstage for a DAC i am building Arduino controlled Dual Mono AK4490 DAC (Part 3) | Dimdim's Blog
So the description (which ofcause also can be read in link) of biasing the circuit is as this :
I was hoping that someone here could point me in the right direction, howto match those transistors for the circuit?
I also attached a schematic from Sound.Elliot which i intend to use maybe for this.
Matching Power and Driver Transistors
I hope i got it explained right, otherwise please ask :)
Best regards; Jesper.
I know it's the wrong place, but i also know that we sometimes need matched transistors for our beloved Pass amp.
Well, long story short; i need to match two "complimentary" transistors, excatly BCP53T which is PNP / https://assets.nexperia.com/document...BCP53T_SER.pdf with an BCP56T (NPN) https://assets.nexperia.com/document...BCP56T_SER.pdf
I need to match T8A with T9A and T8B with T9B on the attached schem.
The thing i build is an class-A outputstage for a DAC i am building Arduino controlled Dual Mono AK4490 DAC (Part 3) | Dimdim's Blog
So the description (which ofcause also can be read in link) of biasing the circuit is as this :
Quote:
|
Power should be ideally +/-16VDC. A bit less is OK. The board is running in class-A so current draw is constant. A power supply with 100mA current capacity should be enough. Bias current is adjusted by the multi-turn trimmers R26A and R26B. They should be adjusted to their mid value before soldering to the board (~1K). To adjust bias just measure current consumption at one of the rails while turning the pot. Adjust for ~25mA total current draw per rail and per channel. Current draw on the negative rail should be about 1mA higher than on the positive rail. |
I also attached a schematic from Sound.Elliot which i intend to use maybe for this.
Matching Power and Driver Transistors
I hope i got it explained right, otherwise please ask :)
Best regards; Jesper.
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Retip possible after potting?
Hi! I have removed the plastic casing of my Denon DL103R, and is considering if I should pot or not? The new body is aluminum. Can the cartridge be retipped after epoxy potting? It seem to me that you will not be able to reach the thin wires of the cartridge if using to much epoxy? I also thought of using acrylic filler (not sure if this is the correct term..) instead of epoxy. It would be difficult, but not impossible to remove, but would it give similar sonic result as epoxy?
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Synchronous Motor Driver for Dual CS522 or CS505 using SM100-1 motor
Synchronous Motor Driver for Dual CS522 or CS505 using SM100-1 motor
Much has been written about the Synchronous motor power supply for turntables. Especially for Linn, Thorens and VPI type turntables, these turntables enjoy a dedicated driver that give them a very good name and also some ridiculous prices. Many turntables below the $1500 price mark using AC motor still rely on a simple capacitor phase delay scheme. The disadvantage is well known : vibration. And hence degraded sound. A motor driver like the case of a Linn Lingo or etc, are too complicated and Expensive. This project shows a motor driver that is cheap to build, with readily available parts, and demonstrated to significantly eliminate the vibration on a Dual SM100-1 motor. The circuit is nothing new, but the investigation shows significant improvement on other turntables that uses AC motor. (eg. Rega)
Using a DC motor to replace the AC motor may not be a final answer. DC motor control is complicated, and may even involve mechanical modification for existing motor mounting. The control scheme may involve a feedback tacho generator, which can also be a problem to implement.
The following system diagram is inspired by Hans Polak in his 2016 post on Optimally driving a (VPI) synchronous turntable motor. I have learned a lot from Hans, Thank you! I have also done some investigations using the Dual CS522 motor and have some interesting findings.
The system diagram explains the concept and strategy
![Click the image to open in full size.]()
The Clock generator is a standard well known 3.2768Mhz Crystal Clock circuit, under going divisions to get 50Hz or 60Hz. The SM100 is a 16 pole motor, so 50hz gives 375 rpm rotational speed. This drives the pulley systems in many CS522 or 505 family turn tables. I verified that the SM100 is able to run at higher frequency of 75hz, and directly drives the platter to give 45rpm on the Dual. However, I want to make use of the mechanical selections available on the Dual, so I focus on getting a very stable 375 rpm with little or no vibration from the SM100 motor. The 4013 D flip flop providing division by 2, twice, is a sensitive circuit, that needs care in soldering and securing to give a stable operation.
![Click the image to open in full size.]()
Filtering is done by an 8th order Butterworth low pass filter. Design is automated using the Anlog Device wizard here Filter Wizard | Analog Devices
The corner frequency is selected at 60Hz, and stop band before the first square wave harmonic of 150Hz for 50Hz. This filter circuit is easy to build and act as a ramp during start up.
![Click the image to open in full size.]()
![Click the image to open in full size.]()
The phase generator can vary the delay from 90 degrees to even further. There were some interesting findings : Delay to further such as 95 , the motor will reach a sweet spot with very little vibration. Advancing the phase to less than 90, of course, will generate more vibration. I cannot explain the delay. This could be physical construction of the SM100 motor. I have checked 3 different SM100 motors, and each has a different sweet spot. Some manual adjustment is needed. Visually, I used the scope to check the delay, but I use my palm to feel the vibration. Delaying the phase further slightly gives a better result.
![Click the image to open in full size.]()
The inverter driver is a simple TDA 2030 Kit, which is sold in Ebay as a stereo subwoofer driver for less than $10 for a built up board. I have changed the gain setting feedback resistor to 5k ohms and the ref resistor 1 k ohms. This amplifier is gain stable and operates at about 55C for extended hours with no further heat sinking required.
![Click the image to open in full size.]()
The output transformers are a pair of 6VA EI type transformers. They are readily available. I have chosen the 230V type so there are more copper and iron in the transformer. The SM100-1 is basically a 115V motor, and in countries like UK the voltage is dropped via a power resistor (which can run very hot within a plastic casing). The 230V type transformer appear to make the TDA2030 cope better in the stepping up of voltage to 115V. I recommend running the motor at 115V and less than 100V the motor may not have sufficient torque.
![Click the image to open in full size.]()
The Dual CS522 or 505 in its original form, has 3 rubber stands that can cope with a vibrating AC motor. This upgrade makes the motor operate as if it is a DC motor. Hence there will be reduced disturbances to the arm. Note that due to the age of the motor, it is recommended to service the motor with a new rotor and new sintered bushings soaked in ester type machine oil. The air gap of the rotor to the stator can be confirmed by inserting stripes of A4 paper during installation. This will ensure there is a uniform air gap, a key to low vibration motor.
After installation, I found that the motor phase sweet spot needed to be further adjusted when it is loaded. The delay was even further than it was running in no load condition. I have yet investigated why this is so. If someone can explain this I will be grateful.
Touching the motor SM100, can hardly feel it is vibrating when in operation. The motor speed is rock solid at 33.33 or 45 rpm. Note that the Dual motor pinion needs to setup properly with reference to Dual service manual, in order to allow the speed adjust and speed select to work flawlessly.
![Click the image to open in full size.]()
I could not hear any motor noise using the stethoscope on the turntable when it is turning. The next step is to mount a new CS505-4 type arm, replace the 5 ball bearings on the support using ceramic type, and verify using listening test to compare with a stock CS522 turntable.
![Click the image to open in full size.]()
Much has been written about the Synchronous motor power supply for turntables. Especially for Linn, Thorens and VPI type turntables, these turntables enjoy a dedicated driver that give them a very good name and also some ridiculous prices. Many turntables below the $1500 price mark using AC motor still rely on a simple capacitor phase delay scheme. The disadvantage is well known : vibration. And hence degraded sound. A motor driver like the case of a Linn Lingo or etc, are too complicated and Expensive. This project shows a motor driver that is cheap to build, with readily available parts, and demonstrated to significantly eliminate the vibration on a Dual SM100-1 motor. The circuit is nothing new, but the investigation shows significant improvement on other turntables that uses AC motor. (eg. Rega)
Using a DC motor to replace the AC motor may not be a final answer. DC motor control is complicated, and may even involve mechanical modification for existing motor mounting. The control scheme may involve a feedback tacho generator, which can also be a problem to implement.
The following system diagram is inspired by Hans Polak in his 2016 post on Optimally driving a (VPI) synchronous turntable motor. I have learned a lot from Hans, Thank you! I have also done some investigations using the Dual CS522 motor and have some interesting findings.
The system diagram explains the concept and strategy
The Clock generator is a standard well known 3.2768Mhz Crystal Clock circuit, under going divisions to get 50Hz or 60Hz. The SM100 is a 16 pole motor, so 50hz gives 375 rpm rotational speed. This drives the pulley systems in many CS522 or 505 family turn tables. I verified that the SM100 is able to run at higher frequency of 75hz, and directly drives the platter to give 45rpm on the Dual. However, I want to make use of the mechanical selections available on the Dual, so I focus on getting a very stable 375 rpm with little or no vibration from the SM100 motor. The 4013 D flip flop providing division by 2, twice, is a sensitive circuit, that needs care in soldering and securing to give a stable operation.
Filtering is done by an 8th order Butterworth low pass filter. Design is automated using the Anlog Device wizard here Filter Wizard | Analog Devices
The corner frequency is selected at 60Hz, and stop band before the first square wave harmonic of 150Hz for 50Hz. This filter circuit is easy to build and act as a ramp during start up.
The phase generator can vary the delay from 90 degrees to even further. There were some interesting findings : Delay to further such as 95 , the motor will reach a sweet spot with very little vibration. Advancing the phase to less than 90, of course, will generate more vibration. I cannot explain the delay. This could be physical construction of the SM100 motor. I have checked 3 different SM100 motors, and each has a different sweet spot. Some manual adjustment is needed. Visually, I used the scope to check the delay, but I use my palm to feel the vibration. Delaying the phase further slightly gives a better result.
The inverter driver is a simple TDA 2030 Kit, which is sold in Ebay as a stereo subwoofer driver for less than $10 for a built up board. I have changed the gain setting feedback resistor to 5k ohms and the ref resistor 1 k ohms. This amplifier is gain stable and operates at about 55C for extended hours with no further heat sinking required.
The output transformers are a pair of 6VA EI type transformers. They are readily available. I have chosen the 230V type so there are more copper and iron in the transformer. The SM100-1 is basically a 115V motor, and in countries like UK the voltage is dropped via a power resistor (which can run very hot within a plastic casing). The 230V type transformer appear to make the TDA2030 cope better in the stepping up of voltage to 115V. I recommend running the motor at 115V and less than 100V the motor may not have sufficient torque.
The Dual CS522 or 505 in its original form, has 3 rubber stands that can cope with a vibrating AC motor. This upgrade makes the motor operate as if it is a DC motor. Hence there will be reduced disturbances to the arm. Note that due to the age of the motor, it is recommended to service the motor with a new rotor and new sintered bushings soaked in ester type machine oil. The air gap of the rotor to the stator can be confirmed by inserting stripes of A4 paper during installation. This will ensure there is a uniform air gap, a key to low vibration motor.
After installation, I found that the motor phase sweet spot needed to be further adjusted when it is loaded. The delay was even further than it was running in no load condition. I have yet investigated why this is so. If someone can explain this I will be grateful.
Touching the motor SM100, can hardly feel it is vibrating when in operation. The motor speed is rock solid at 33.33 or 45 rpm. Note that the Dual motor pinion needs to setup properly with reference to Dual service manual, in order to allow the speed adjust and speed select to work flawlessly.
I could not hear any motor noise using the stethoscope on the turntable when it is turning. The next step is to mount a new CS505-4 type arm, replace the 5 ball bearings on the support using ceramic type, and verify using listening test to compare with a stock CS522 turntable.
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FS: Stuff I dont need anymore
Here I want to sell the following stuff:
1. Fully build and working condition Sigma22 linear dual rail power supply from AMB labs set to +-24V. (the voltage can be set to other voltages needed) I have two boards available for sale! Price 120 USD / regulator
2. NEW never used diyAB "Honey Badger" Class AB Power Amp - 150W/Channel PCB boards for the wonderful class A/B amp. Price: 39 USD
3. NEW M2X boards set for the firstwatt clone M2 amplifier. Price 29 USD + 71 USD for the already build MountainView and Ishikawa modules (original toshiba 2sk170/2sj79 transistors)
Shipping worldwide via priority mail.
Item location EU.
1. Fully build and working condition Sigma22 linear dual rail power supply from AMB labs set to +-24V. (the voltage can be set to other voltages needed) I have two boards available for sale! Price 120 USD / regulator
2. NEW never used diyAB "Honey Badger" Class AB Power Amp - 150W/Channel PCB boards for the wonderful class A/B amp. Price: 39 USD
3. NEW M2X boards set for the firstwatt clone M2 amplifier. Price 29 USD + 71 USD for the already build MountainView and Ishikawa modules (original toshiba 2sk170/2sj79 transistors)
Shipping worldwide via priority mail.
Item location EU.
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Transistors equivalent parts
Hi, I hope posted the thread in right section.
I have some driver and power transistors dead and I want find a good replacement with specs as close possible to the originals.
Appreciate any helps!
Thanks
Here the parts:
2SC897 (SCHEMATIC SHOW 2SD217)
2SC959
2SA606
2SA762
2SD427
2SB557
Thanks all
S.
I have some driver and power transistors dead and I want find a good replacement with specs as close possible to the originals.
Appreciate any helps!
Thanks
Here the parts:
2SC897 (SCHEMATIC SHOW 2SD217)
2SC959
2SA606
2SA762
2SD427
2SB557
Thanks all
S.
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