Bought belt idler roller kit for my deck, your opinion (pic attached)
- By UniQ
- Analogue Source
- 1 Replies
So I have an old Nakamichi BX-125 which was in need for new set of fresh rubber and bought a generic replacement kit on ebay, the 2 belts and roller looked pretty nice visually, but the idler (see pic below) has a pretty poor surface finish full of larger holes, how much will this affect wow and flutter?
It's not a huge deal as it was pretty low cost anyway, but wondering should I give a positive, neutral or negative feedback on this, the seller didn't give any feedback yet which I consider another slight negative as I have already fulfilled my bit of the transaction and puts a pressure on the buyer to give a positive feedback in fear of receiving less than positive feedback in return, most sellers do give a feedback immediately after payment without awaiting the buyers feedback.
It's not a huge deal as it was pretty low cost anyway, but wondering should I give a positive, neutral or negative feedback on this, the seller didn't give any feedback yet which I consider another slight negative as I have already fulfilled my bit of the transaction and puts a pressure on the buyer to give a positive feedback in fear of receiving less than positive feedback in return, most sellers do give a feedback immediately after payment without awaiting the buyers feedback.
Attachments
low cost USBi programmer using cypress CY7C68013A board
- By basreflex
- Digital Line Level
- 81 Replies
Attachments
For Sale SEAS Excel W21EX001
For sale 1 Pair of SEAS Excel W21EX001,very good condition, like new,used 2 years,origin latest production SEAS by AlexAudio
500 Euros shipping not included (France)
500 Euros shipping not included (France)
For Sale F5Pi Voltage Gain Stage + M2 Output Stage (with matched transistors)
- By pinnocchio
- Swap Meet
- 3 Replies
3.5Way - XO design and measurements
- By dptucunduva
- Multi-Way
- 9 Replies
Hi All!
I am building my first 3.5Way floorstanding speakers. I selected the drivers, designed the enclosure and built a test version, using scrap MDF that I had laying around my shop. The idea was to validate that it is a feasible project. Drivers are:
- Tweeter: Peerless XT25SC90-04
- Mid: HiVi Research DMB-A soft dome
- Mid Bass: Vifa P17WJ-00-08
- Woofers: Generic Aiyima chinese 8" woofers. I will be in the US by the end of the year and will get Dayton Audio DC200-8 8" Classic woofers. Box volume was already defined using Dayton's drivers.
The test box is built and I've just took a few measurements of each driver. I used REW in my macbook connected to a cheap car amplifier and a dayton audio umm-6 calibrated USB microphone, at 1m and aligned with the Mid dome (which is the height my ears will be when listening).
I also took measurements in my dedicated listening room, where I will put the speaker. In this case, the microphone was about 2,7 meters away and the speaker was toed out about 15 degrees.
Now comes the question. For each measurement, I generated a set of frd files, imported on VirtuixCad and designed a crossover. I expected the measurements to be different, but the differences that I found seem to be a little too much (do not mind the average SPL - i've used different volumes in each measurement).
This is the XO based (alpha draft version 😂) on the in-room measurement (do not mind the fact that it has only one woofer - I measured both woofers in parallel in a single sweep):
This is the XO (also alpha draft version 😂) based on the outdoor measurement:
I understand that reflections, room modes, etc would change the frequency response (that is noticeable specially below 200hz), but the huge phase difference that I am seeing - which is changing drastically crossover points and driver polarity - is bothering me a lot.
What could be causing this? Maybe the distance between the speaker and the microphone, which changes a lot the time arrival of each driver?
One last info: I am using in-room measurements because the speaker will be there for a long time. I will be using it in this room to listen to music only (for movies, the current setup that you see in the pictures will be used). So i am aiming for a passive XO that is tailor made for my room.
I would love to hear your insights.
Thanks!
I am building my first 3.5Way floorstanding speakers. I selected the drivers, designed the enclosure and built a test version, using scrap MDF that I had laying around my shop. The idea was to validate that it is a feasible project. Drivers are:
- Tweeter: Peerless XT25SC90-04
- Mid: HiVi Research DMB-A soft dome
- Mid Bass: Vifa P17WJ-00-08
- Woofers: Generic Aiyima chinese 8" woofers. I will be in the US by the end of the year and will get Dayton Audio DC200-8 8" Classic woofers. Box volume was already defined using Dayton's drivers.
The test box is built and I've just took a few measurements of each driver. I used REW in my macbook connected to a cheap car amplifier and a dayton audio umm-6 calibrated USB microphone, at 1m and aligned with the Mid dome (which is the height my ears will be when listening).
I also took measurements in my dedicated listening room, where I will put the speaker. In this case, the microphone was about 2,7 meters away and the speaker was toed out about 15 degrees.
Now comes the question. For each measurement, I generated a set of frd files, imported on VirtuixCad and designed a crossover. I expected the measurements to be different, but the differences that I found seem to be a little too much (do not mind the average SPL - i've used different volumes in each measurement).
This is the XO based (alpha draft version 😂) on the in-room measurement (do not mind the fact that it has only one woofer - I measured both woofers in parallel in a single sweep):
This is the XO (also alpha draft version 😂) based on the outdoor measurement:
I understand that reflections, room modes, etc would change the frequency response (that is noticeable specially below 200hz), but the huge phase difference that I am seeing - which is changing drastically crossover points and driver polarity - is bothering me a lot.
What could be causing this? Maybe the distance between the speaker and the microphone, which changes a lot the time arrival of each driver?
One last info: I am using in-room measurements because the speaker will be there for a long time. I will be using it in this room to listen to music only (for movies, the current setup that you see in the pictures will be used). So i am aiming for a passive XO that is tailor made for my room.
I would love to hear your insights.
Thanks!
Adding NFB to 12AU7 pre
- By Painkiller
- Tubes / Valves
- 89 Replies
I have a bit too much gain in my system, so I need to reduce the output of my pre. I'm new to tubes, so I was thinking I'll just ask. Is there any way to successfully add NFB to this circuit?
My first tuby
- By systux
- Tubes / Valves
- 23 Replies
After lurking dozens of years here on diyaudio , I decided to build my own riaa tube preamps.
After retirement I recently picked up an old hobby, tubes and amps, combined with a renewed interest in playing vinyl , I acquired some pcb's on aliexpress. One board was based on the Mofi riaa mm/mc preamp, two dual opamps opa1652, two voltage regulators for symmetric psu ,+18V and -18V, and the split active low boost - passive high roll-off riaa network, ready in no time, and sounded quite nice, no hum, noise or other inconveniences, but not very satisfying to listen to.
After some reading on the internet, I got interested in some tube based riaa preamps, in particular the ear384 which seems a shunt feedback design, the Joe Tritschler split passive high - shunt fb active low boost design with unobtainable tubes , and the JL Hood , originally solid state but translated to tubes-mosfet hybrid by me, split series feedback low boost and shunt fb high roll-off design. To that end I acquired two pcb's from aliexpress, one designed for the ear384 design and one for the shure M65 preamp. I wasn't very impressed with the sound of the Mofi ear384, it seemed to have more than twice the voltage output at 20kHz than at 20Hz. Measured with an inverse riaa filter , modelled after the design on Rod Elliot's webpages, with the 1k gain setting resistor altered to 590R , much closer to the original 604R from this design, with all inverse riaa components selected to be within 0.1% of the target values, this fed by a GFG-8015 function generator. So I changed that to the tube-mosfet hybrid JL Hood design:
A few errors , the 43R from the shunt feedback network is connected after the 3.3uF capacitor and the 590R isn't there.
This was a lot better to my ears. Allso measurements with the inverse riaa filter seemed to indicate a much better riaa conformance , with deviations <0.2dB , and a slight roll of at 20kHz, depending on the actual value of the 81.5pF capacitor. The CCS loading the ecc83 is made out of a J112 jfet and a cpc3960 depletion mode mosfet with ca 1mA current. The active low boost riaa feedback network is targeted at around 4mA current. The capacitor parallel to the source resistor can be made into a rudimentary rumble filter. The 6J52P pentode can be anything , ef184 e280f e180f e186f e810f or 6j11p. This my not very tidy test model:
Two gas discharge tubes for ca. 289V stabilized HT and a LM317 for a stabilized 12.6V , the two 6J52P tubes here used run heaters in series, just like the single ecc83. Riaa componenets are selected to match between left and right channel. Because of the feedback design tube matching on gain is less relevant and left and rigt outputs match very nicely.
I allso read much regard for a completely passive design, so I used the shure M65 board to make a complete passive design:
Again a hybrid design , with a 2sk117 jfet cascading into a 6BK7A triode , here cascoding the jfet and the triode would give higher gain, but I wanted to have a line level output voltage. Output is buffered by the ccs loaded mosfet source follower, whereafter the passive riaa network, the values shown gave me the best riaa conformance, though official calculations give sligtly different values. The second triode is ccs loaded with the "mu?" output used as the output. The 825R for the cathode, unbypassed, is to limit output voltage , a LM385Z-adj. would yield more gain, but I wanted to keep the output at approx. line level. This amp allso sounded very nice , though somewhat softer in tone , but absolute no listening fatigue, so much so I have to reconsider playing records because the cost of good needles is pretty inflating my household budget. This is the modified shur M65 pcb:
I couldn't decide which was the better of the above two designs, or the solid state mofi design. I find the tube designs more interesting to listen to, I think mainly because of the looks, with solid state there ain't much to look at, and , despite what people might say, looks count for the listening experience.
To listen to the tube riaa preamps , I allso decided to build an integrated power tube amp, consisting of the standard PP power amp, a tube based tone control, and a builtin riaa preamp.
It's based om el86/6p43p tubes , with a 6BK7A based LTP phase splitter ,ccs in the tail to the -50V ,and a shared ecc83 input tube for L and R channels. The tone control is based on the ecc832 , the AU halve is used as the CF input with the AX halve serving as the actual tone control triode, baxandall type, so no gain in mid position. Both loaded with ccs's made of a J112 and a CPC3960, 4mA for the AU and 1.2mA for the AX , wherev the "mu" output is used for connecting to the power amp input. The riaa preamp is based on the Joe Tritschler passive -active shunt fb design, but with ecc83 tubes, a 2sk208 cascading into the the ecc83 as input, that is ccs loaded with 1.2mA , with the mu output loaded with the passive riaa high roll-of. It's cathode held at fixed voltage by two LM385Z-5 vref's that need only 10 micro A to work properly, and with 1Ohm dynamic resitance no capacitor for AC is needed. The second triode halve , allso ccs loaded with 1.2mA functions as the low boost shunt feedback amp and output to the volume pot. This riaa preamp allso sounds very good, albeit not as "clean" as the other two. The whole amp is fed by a smps , supposedly 300Watt, I got cheap from aliexpress. It's advertised to deliver 300V/600mA, 12.6V/?A , 6.3V/?A and -50V/100mA . Actual output voltages weren't that good. The 6.3V has it's own switcher to make the 6.3V from the 12.6V output. It gave under load only 5.9V and I had to change the feedback resistor value to the switcher to a slightly higher value, it's now 6.23V which seems close enough. The 12.6V was only 12.18V, after allso changing the feedback resitor to the calculated necessary value I got 12.54V , close enough, which allso brought the HT output from 278V to 283V, still quite some lower than the advertised 300V , but since I was using el86 tubes in standerd UL PP design, it was more than enough. Loaded with 5k OPT's , it delivers 18Watts per channel , constant tone test.
The amplifier has no appreciable hum or noise when line level inputs are selected and volume max with ear against speaker cone, but considerable hum when one of the riaa preamps is selected. The seperate riaa preamps have transformer psu's and sound more open than the built-in riaa preamp, but all have equal loud hum with volume at max. Might the smps be the reason for the less open sounding built-in riaa preamp ? I do see a lot of HF dirt on the several supply lines, in the 100kHz till 1MHz range. After changing the power supply input capacitor from the low quality 150uF 400V type to a brand quality 390uF 450V it was less, but still. From scope readings it seems to operate around the 115kHz region and is of the LLC resonant type. The output supply lines have no inductors , like you see in computer psu's. What would be usable types for this frequency and application? The tone control and power amp don't seem to suffer that much from the smps, but I have the idea the riaa preamp has. The tone control and riaa tubes are HT fed by a voltage regulator that brings down the 283V HT to 253V. I tried shielding the smps but that didn't had much effect. Allso, a signicant 50Hz ripple is present on the supply lines , as I understood from reading several papers, caused by the capacitor between the groundplanes of the power input and the supply output. Is there a preferred way of grounding this contraption. I now have a earthed power entry with HF filter to supress HF bleeding into the powerlines and at the supply side a bus ground connected to the power earth entry. Power ground is o.c. not connected. to any of earth or supply ground , except for the capacitor between the power ground and supply ground, which is there for safety reasons as I could make up of reading of the appropriate papers.
And the hum, how could I get most of the hum removed, when I connect the record player through the mofi solid state preamp, no hum at all, when I use one of the 3 tube riaa preamps lots of hum. I have to say that at the normal listening levels of the volume knob , there is no hum noticeable in listening position, only a bit with ear against speaker.
In the end I would say that all riaa preamps, when built to standards sound the same, with the fully active a bit more snappy and the fully passive a bit more airy , and the in-betweens , well , in between. The solid state preamp has no hum or noise issues whatsover, but is uninspiring and a bit flat sounding, probably mainly it doesn't look that good. The tube based riaa preamp are hummy at max volume, couldn't figure out where that comes from, grounding is exactly the same as with the solid state preamp. Noise is allso not a preblem for the tube preamps, though the smps fed riaa preamp seems to suffer a bit in cleanliness, hard to tell. I will at one point replace the smps with a transformer based psu, see how that goes. I am not sure if I hear that right, but smps seems to compress the audio a bit, but than again, might be completely subjective, knowing what you listen to might make you hear things that aren't there. Anyways, all the riaa preamps seem to perform quite well. The mofi ear384 and the shure M65 , the original designs for two of the pcb's I had bought sounded dreadful and very fatiguing, not recommended. I think I like the fully passive design best for acoustic/classical music and the JL Hood active series - active shunt design best for the electrified classic blues, blues-rock etc. music I like to listen to. Any comments on the designs would be appreciated. I am no electronics engineer so there might be a lot to comment on, all designs are cobbled together from bits and pieces I found lurking throught diyudio and the internet in general.
Thanks for reading this travel log into tubesland.
Systux
After retirement I recently picked up an old hobby, tubes and amps, combined with a renewed interest in playing vinyl , I acquired some pcb's on aliexpress. One board was based on the Mofi riaa mm/mc preamp, two dual opamps opa1652, two voltage regulators for symmetric psu ,+18V and -18V, and the split active low boost - passive high roll-off riaa network, ready in no time, and sounded quite nice, no hum, noise or other inconveniences, but not very satisfying to listen to.
After some reading on the internet, I got interested in some tube based riaa preamps, in particular the ear384 which seems a shunt feedback design, the Joe Tritschler split passive high - shunt fb active low boost design with unobtainable tubes , and the JL Hood , originally solid state but translated to tubes-mosfet hybrid by me, split series feedback low boost and shunt fb high roll-off design. To that end I acquired two pcb's from aliexpress, one designed for the ear384 design and one for the shure M65 preamp. I wasn't very impressed with the sound of the Mofi ear384, it seemed to have more than twice the voltage output at 20kHz than at 20Hz. Measured with an inverse riaa filter , modelled after the design on Rod Elliot's webpages, with the 1k gain setting resistor altered to 590R , much closer to the original 604R from this design, with all inverse riaa components selected to be within 0.1% of the target values, this fed by a GFG-8015 function generator. So I changed that to the tube-mosfet hybrid JL Hood design:
A few errors , the 43R from the shunt feedback network is connected after the 3.3uF capacitor and the 590R isn't there.
This was a lot better to my ears. Allso measurements with the inverse riaa filter seemed to indicate a much better riaa conformance , with deviations <0.2dB , and a slight roll of at 20kHz, depending on the actual value of the 81.5pF capacitor. The CCS loading the ecc83 is made out of a J112 jfet and a cpc3960 depletion mode mosfet with ca 1mA current. The active low boost riaa feedback network is targeted at around 4mA current. The capacitor parallel to the source resistor can be made into a rudimentary rumble filter. The 6J52P pentode can be anything , ef184 e280f e180f e186f e810f or 6j11p. This my not very tidy test model:
Two gas discharge tubes for ca. 289V stabilized HT and a LM317 for a stabilized 12.6V , the two 6J52P tubes here used run heaters in series, just like the single ecc83. Riaa componenets are selected to match between left and right channel. Because of the feedback design tube matching on gain is less relevant and left and rigt outputs match very nicely.
I allso read much regard for a completely passive design, so I used the shure M65 board to make a complete passive design:
Again a hybrid design , with a 2sk117 jfet cascading into a 6BK7A triode , here cascoding the jfet and the triode would give higher gain, but I wanted to have a line level output voltage. Output is buffered by the ccs loaded mosfet source follower, whereafter the passive riaa network, the values shown gave me the best riaa conformance, though official calculations give sligtly different values. The second triode is ccs loaded with the "mu?" output used as the output. The 825R for the cathode, unbypassed, is to limit output voltage , a LM385Z-adj. would yield more gain, but I wanted to keep the output at approx. line level. This amp allso sounded very nice , though somewhat softer in tone , but absolute no listening fatigue, so much so I have to reconsider playing records because the cost of good needles is pretty inflating my household budget. This is the modified shur M65 pcb:
I couldn't decide which was the better of the above two designs, or the solid state mofi design. I find the tube designs more interesting to listen to, I think mainly because of the looks, with solid state there ain't much to look at, and , despite what people might say, looks count for the listening experience.
To listen to the tube riaa preamps , I allso decided to build an integrated power tube amp, consisting of the standard PP power amp, a tube based tone control, and a builtin riaa preamp.
It's based om el86/6p43p tubes , with a 6BK7A based LTP phase splitter ,ccs in the tail to the -50V ,and a shared ecc83 input tube for L and R channels. The tone control is based on the ecc832 , the AU halve is used as the CF input with the AX halve serving as the actual tone control triode, baxandall type, so no gain in mid position. Both loaded with ccs's made of a J112 and a CPC3960, 4mA for the AU and 1.2mA for the AX , wherev the "mu" output is used for connecting to the power amp input. The riaa preamp is based on the Joe Tritschler passive -active shunt fb design, but with ecc83 tubes, a 2sk208 cascading into the the ecc83 as input, that is ccs loaded with 1.2mA , with the mu output loaded with the passive riaa high roll-of. It's cathode held at fixed voltage by two LM385Z-5 vref's that need only 10 micro A to work properly, and with 1Ohm dynamic resitance no capacitor for AC is needed. The second triode halve , allso ccs loaded with 1.2mA functions as the low boost shunt feedback amp and output to the volume pot. This riaa preamp allso sounds very good, albeit not as "clean" as the other two. The whole amp is fed by a smps , supposedly 300Watt, I got cheap from aliexpress. It's advertised to deliver 300V/600mA, 12.6V/?A , 6.3V/?A and -50V/100mA . Actual output voltages weren't that good. The 6.3V has it's own switcher to make the 6.3V from the 12.6V output. It gave under load only 5.9V and I had to change the feedback resistor value to the switcher to a slightly higher value, it's now 6.23V which seems close enough. The 12.6V was only 12.18V, after allso changing the feedback resitor to the calculated necessary value I got 12.54V , close enough, which allso brought the HT output from 278V to 283V, still quite some lower than the advertised 300V , but since I was using el86 tubes in standerd UL PP design, it was more than enough. Loaded with 5k OPT's , it delivers 18Watts per channel , constant tone test.
The amplifier has no appreciable hum or noise when line level inputs are selected and volume max with ear against speaker cone, but considerable hum when one of the riaa preamps is selected. The seperate riaa preamps have transformer psu's and sound more open than the built-in riaa preamp, but all have equal loud hum with volume at max. Might the smps be the reason for the less open sounding built-in riaa preamp ? I do see a lot of HF dirt on the several supply lines, in the 100kHz till 1MHz range. After changing the power supply input capacitor from the low quality 150uF 400V type to a brand quality 390uF 450V it was less, but still. From scope readings it seems to operate around the 115kHz region and is of the LLC resonant type. The output supply lines have no inductors , like you see in computer psu's. What would be usable types for this frequency and application? The tone control and power amp don't seem to suffer that much from the smps, but I have the idea the riaa preamp has. The tone control and riaa tubes are HT fed by a voltage regulator that brings down the 283V HT to 253V. I tried shielding the smps but that didn't had much effect. Allso, a signicant 50Hz ripple is present on the supply lines , as I understood from reading several papers, caused by the capacitor between the groundplanes of the power input and the supply output. Is there a preferred way of grounding this contraption. I now have a earthed power entry with HF filter to supress HF bleeding into the powerlines and at the supply side a bus ground connected to the power earth entry. Power ground is o.c. not connected. to any of earth or supply ground , except for the capacitor between the power ground and supply ground, which is there for safety reasons as I could make up of reading of the appropriate papers.
And the hum, how could I get most of the hum removed, when I connect the record player through the mofi solid state preamp, no hum at all, when I use one of the 3 tube riaa preamps lots of hum. I have to say that at the normal listening levels of the volume knob , there is no hum noticeable in listening position, only a bit with ear against speaker.
In the end I would say that all riaa preamps, when built to standards sound the same, with the fully active a bit more snappy and the fully passive a bit more airy , and the in-betweens , well , in between. The solid state preamp has no hum or noise issues whatsover, but is uninspiring and a bit flat sounding, probably mainly it doesn't look that good. The tube based riaa preamp are hummy at max volume, couldn't figure out where that comes from, grounding is exactly the same as with the solid state preamp. Noise is allso not a preblem for the tube preamps, though the smps fed riaa preamp seems to suffer a bit in cleanliness, hard to tell. I will at one point replace the smps with a transformer based psu, see how that goes. I am not sure if I hear that right, but smps seems to compress the audio a bit, but than again, might be completely subjective, knowing what you listen to might make you hear things that aren't there. Anyways, all the riaa preamps seem to perform quite well. The mofi ear384 and the shure M65 , the original designs for two of the pcb's I had bought sounded dreadful and very fatiguing, not recommended. I think I like the fully passive design best for acoustic/classical music and the JL Hood active series - active shunt design best for the electrified classic blues, blues-rock etc. music I like to listen to. Any comments on the designs would be appreciated. I am no electronics engineer so there might be a lot to comment on, all designs are cobbled together from bits and pieces I found lurking throught diyudio and the internet in general.
Thanks for reading this travel log into tubesland.
Systux
Audio garage sale. Fane 15'' fullrange drivers in mint condition (FC152F01-TC)
- By tommydoan84
- Swap Meet
- 1 Replies
Originally purchased an OEM pair of Fane FC1502F01 from Thomman music in Germany. Still ub original box and moved on with different DIY projects. The pair is in absolute mint condition!! So many projects. Too little time
Selling price is 50 USD + Shipping cost via Paypal to local 48 CONUS
Spec is here:
https://www.fane-international.com/downloads/Fane-FC152F01-DS280417.pdf
There's a whole thread from DIYaudio forum talking about this speaker build
https://www.diyaudio.com/forums/full-range/308652-15-range-fane.html
I live in San Diego, CA so local pick up is more than welcome to save shipping cost.
This sale is only for US local. No international shipping.
Thanks,
IMG_9765
IMG_9766
IMG_9769 (1)
IMG_9776
IMG_9859
IMG_9860
Selling price is 50 USD + Shipping cost via Paypal to local 48 CONUS
Spec is here:
https://www.fane-international.com/downloads/Fane-FC152F01-DS280417.pdf
There's a whole thread from DIYaudio forum talking about this speaker build
https://www.diyaudio.com/forums/full-range/308652-15-range-fane.html
I live in San Diego, CA so local pick up is more than welcome to save shipping cost.
This sale is only for US local. No international shipping.
Thanks,
IMG_9765 IMG_9766 IMG_9769 (1) IMG_9776 IMG_9859 IMG_9860
The ultimate OTL6080
- By tubelectron
- Tubes / Valves
- 226 Replies
Hi All,
I've been off for a while : no time, not much money to devote to... 🙁
My last Audio Hi-Fi build I posted was The ULTIMATE 300B :
In the same vein (same format, same chassis) I am building the prototype of what should be (one day) The ULTIMATE OTL6080 :
General layout of what should be a mono block :
Amp section prototype only, for tests and qualification purposes, same disposition as layout :
I have to build the PSU prototype now, in the days to come.
Wait and See ! 😉
A+!
I've been off for a while : no time, not much money to devote to... 🙁
My last Audio Hi-Fi build I posted was The ULTIMATE 300B :
In the same vein (same format, same chassis) I am building the prototype of what should be (one day) The ULTIMATE OTL6080 :
General layout of what should be a mono block :
Amp section prototype only, for tests and qualification purposes, same disposition as layout :
I have to build the PSU prototype now, in the days to come.
Wait and See ! 😉
A+!
Adding a remote control to the SPL Volume 2 preamp
- By movie_fan
- Analog Line Level
- 4 Replies
Hello everybody!!
A SPL Volume 2 preamp is coming my way, and I'll be looking into adding remote controlled volume to it.
Looking around, there's this kind of motorized volume control kits: https://www.aliexpress.us/item/3256802832503035.html
They seem relatively straight-forward, but there's not much space inside the SPL preamp for adding the control kit to it:
At any rate, would you think this approach is feasible?
TIA!! 🙂
A SPL Volume 2 preamp is coming my way, and I'll be looking into adding remote controlled volume to it.
Looking around, there's this kind of motorized volume control kits: https://www.aliexpress.us/item/3256802832503035.html
They seem relatively straight-forward, but there's not much space inside the SPL preamp for adding the control kit to it:
At any rate, would you think this approach is feasible?
TIA!! 🙂
Wire and connectors embedded in resin - how to remove? Martin Logan Prodigy
- By bchow
- Planars & Exotics
- 30 Replies
One of the connectors that connect the panel to the electronics of my Martin Logan Prodigy has failed. This is a known issue at ML but they no longer have the connector available.
Does anyone have any ideas how I can remove that resin-like substance that the wires are embedded in? I would like to remove that to access the bare wires/connectors to fix the bad connection.
Or better yet, if anyone knows where I can get a new one that would be amazing. The connector is called Pulse-lok from Alden. Unfortunately ML says it is no longer available.
Does anyone have any ideas how I can remove that resin-like substance that the wires are embedded in? I would like to remove that to access the bare wires/connectors to fix the bad connection.
Or better yet, if anyone knows where I can get a new one that would be amazing. The connector is called Pulse-lok from Alden. Unfortunately ML says it is no longer available.
Copy-cat Drivers
It would be quite fun to test these.
KEF Clone DZ05
KEF Clone DZ 06
Scanspeak Clone EY04
SB Acoustics CDC Tweeter kind of clone
KEF Clone DZ05
KEF Clone DZ 06
Scanspeak Clone EY04
SB Acoustics CDC Tweeter kind of clone
DIY spherical ESL
- By MarkRehorst
- Planars & Exotics
- 28 Replies
Moving this from the thread on DIY spherical speakers...
For those who haven't seen the previous posts, I am looking at using a 3D printer to produce a "spherical" ESL with 12 drivers about 200 mm in diameter each arranged on the surface of a truncated dodecahedron. The printed parts will serve as structural elements as well as the stator supports for wire screen stators unless I can find a cheap source of perforated sheet metal discs. Diaphragms will be 6 um polyester with Licron coating.
The diaphragm side of the printed parts will print on the printer's bed so they will be smooth and flat. My printer has a 300x300 mm cast aluminum tooling plate bed with a layer of PEI. I am planning to use ABS to print the actual speaker parts and will solvent weld them together using acetone. I have printed some 100 mm stator pieces and a gluing jig to test the accuracy of the printer.
Today I redesigned and printed the gluing jig for the smaller test build before I commit to the full size speaker build, and welded one hemisphere together. I used ethyl acetate (sold as MEK substitute) to solvent weld the 3D printed PETG parts together. As I was gluing it occurred to me that the jig may not be necessary- strategically placed binder clips might do the job just fine. It takes just a tiny drop of the solvent and the joint is secure in a less than a minute.
When I set the glued up assembly down on a flat table all the surfaces on the bottom of the assembly touch the table so I think the printer is producing the prints with accurate angles. The surfaces that are welded looked like they were parallel to each other. I will print the other 6 individual stator pieces and glue them together and see how the two assemblies line up. Then it will be on to more of the design work for the actual drivers.
Note- the print quality is less than ideal- I have a 1mm nozzle on the machine so retraction doesn't work worth a damn resulting in blobby defects. I'll probably switch to a smaller nozzle where I can use retraction effectively for the final prints.
This is a truncated dodecahedron:
Three of the outer stators pieces (red) in the gluing jig (blue). The orange piece is one of the inner stator pieces:
Here is a hemisphere made from the small, test-sized outer stator pieces:
It will be interesting to see if the diaphragm tension causes the stator pieces to flex out of shape. I'll probably add some supports for the wire screen to the inner and outer stator pieces, as well as some means to add dust covers to each driver using the same 6um film as the diaphragms. I still have to work out details of the electrical connections.
For those who haven't seen the previous posts, I am looking at using a 3D printer to produce a "spherical" ESL with 12 drivers about 200 mm in diameter each arranged on the surface of a truncated dodecahedron. The printed parts will serve as structural elements as well as the stator supports for wire screen stators unless I can find a cheap source of perforated sheet metal discs. Diaphragms will be 6 um polyester with Licron coating.
The diaphragm side of the printed parts will print on the printer's bed so they will be smooth and flat. My printer has a 300x300 mm cast aluminum tooling plate bed with a layer of PEI. I am planning to use ABS to print the actual speaker parts and will solvent weld them together using acetone. I have printed some 100 mm stator pieces and a gluing jig to test the accuracy of the printer.
Today I redesigned and printed the gluing jig for the smaller test build before I commit to the full size speaker build, and welded one hemisphere together. I used ethyl acetate (sold as MEK substitute) to solvent weld the 3D printed PETG parts together. As I was gluing it occurred to me that the jig may not be necessary- strategically placed binder clips might do the job just fine. It takes just a tiny drop of the solvent and the joint is secure in a less than a minute.
When I set the glued up assembly down on a flat table all the surfaces on the bottom of the assembly touch the table so I think the printer is producing the prints with accurate angles. The surfaces that are welded looked like they were parallel to each other. I will print the other 6 individual stator pieces and glue them together and see how the two assemblies line up. Then it will be on to more of the design work for the actual drivers.
Note- the print quality is less than ideal- I have a 1mm nozzle on the machine so retraction doesn't work worth a damn resulting in blobby defects. I'll probably switch to a smaller nozzle where I can use retraction effectively for the final prints.
This is a truncated dodecahedron:
Three of the outer stators pieces (red) in the gluing jig (blue). The orange piece is one of the inner stator pieces:
Here is a hemisphere made from the small, test-sized outer stator pieces:
It will be interesting to see if the diaphragm tension causes the stator pieces to flex out of shape. I'll probably add some supports for the wire screen to the inner and outer stator pieces, as well as some means to add dust covers to each driver using the same 6um film as the diaphragms. I still have to work out details of the electrical connections.
aleph 0 biasing
Hi Folks,
Got Aleph 0 from a friend to overlook. Figured out it needs dc re-adjusting and rebiasing. For DC offset it is quite clear, the right pot does the thing. But I am feeling a bit lost with biasing. I understand the left pot is setting the bias, but what is the best way to measure? Points and values, if you don't hesitate.
Thanks in advance.
Got Aleph 0 from a friend to overlook. Figured out it needs dc re-adjusting and rebiasing. For DC offset it is quite clear, the right pot does the thing. But I am feeling a bit lost with biasing. I understand the left pot is setting the bias, but what is the best way to measure? Points and values, if you don't hesitate.
Thanks in advance.
NAD C 525BEE strange skipping...possibly solved
- By Pernas
- Digital Source
- 2 Replies
Hi!
Another NAD-issue here but hopefully solved by now. I guess skipping is more or less strange (and annoying) when it happens.
However, this one didn't make any sense due to the following:
- The C 525BEE quickly handled all my (troublesome) CD/CD-R/CD-RW's without any issues plus is remarkable resistent to movement during playback...not
at all like a player that struggles to read due to a weak laser...
And now the issue, many longer CD's (>=40min) started to skip towards the end.
Well, I opened the little bugger and while everything looked very nice:
However, after using it for a while I noticed the following little "collision" between the white flat ribbon and the black AC wires from the transformer. (Fixed in these photos).
The "collision" took place at the red markup below:
After moving the AC wires away they are never close to each other anymore and haven't heard a skip since then.
Could this really have been the root cause for the skipping - I hope so anyway and I'm a happy NAD CD listener now 🙂
/Per
Another NAD-issue here but hopefully solved by now. I guess skipping is more or less strange (and annoying) when it happens.
However, this one didn't make any sense due to the following:
- The C 525BEE quickly handled all my (troublesome) CD/CD-R/CD-RW's without any issues plus is remarkable resistent to movement during playback...not
at all like a player that struggles to read due to a weak laser...
And now the issue, many longer CD's (>=40min) started to skip towards the end.
Well, I opened the little bugger and while everything looked very nice:
However, after using it for a while I noticed the following little "collision" between the white flat ribbon and the black AC wires from the transformer. (Fixed in these photos).
The "collision" took place at the red markup below:
After moving the AC wires away they are never close to each other anymore and haven't heard a skip since then.
Could this really have been the root cause for the skipping - I hope so anyway and I'm a happy NAD CD listener now 🙂
/Per
Project Ryu - DIY Field Coil Loudspeaker
Hello,
***First i want to say I'm not sure if i should post this under Fullrange or Multiway. Since at this point, there is a high posibility of the need for a supertweeter i chose Multiway forums. I won't mind tho if moderators think it's more suited for Fullrange forums.
About 6 months ago, i started thinking about a DIY fieldcoil speaker. I know opinions vary quite a lot on this matter and so i will do my best to offer as much data as possible for things to be judged objectively. Since that time I have been talking with some fellow countrymen and audio enthusiasts about this project and these conversations helped me in making some of the design decisions. The work is still in progress and i hope your opinions and comments can help tune it to higher performance.
To begin, here are the basic aspects about this project:
- field coil underhung motor structure
- 12" diameter
- Wide range (up to 10kHz), hopefully fullrange (up to 20kHz)
- high efficiency
- to be used in BLH
My personal taste in sound is that i like it when it comes out of large radiating surfaces. Large SD, large horn mouths etc. I think it's a necesity when one tries to reach real, live music levels and at the same time keep a good response to instruments' attack, sustain and decay. This is the reason i chose 12 inch diameter. I would've liked 15" better but it would've been too difficult to make it wide range. Perphaps a future project.
Field Coil Motor Structure:
I have spent a lot of time looking for other field coil projects, for any information on FC design or about available products and i have to say there isn't
much out there. From the pictures of opened FC units i could see a basic shape of the pole pieces. I have to say this is amongst the first design issues i encountered, there isn't much freedom to design these pole pieces, not like the case with permanent magnets anyway.
The next thing one can notice is that the new FCs are low impedance type and this is easily understandable. I have decided that my field coil will also work with 12-15V supply.
Underhung design means thick top plate. Of course this will cause a drop in flux density in the gap. The compromise here i found to be between flux density value and voice coil excursion. Since this speaker will mostly be used horn loaded i sacrificied Xmax to make a thinner top plate. I use standard 1010 steel with a maximum of 0.13% carbon, the best i could get my hands on.
I ran simmulations in FEMM for different values of top plate thickness, FC's number of turns, dimension, wire diameter etc. Here are the results i stopped at:
- magnetic gap height: 12mm
- magnetic gap width: 1-1.5mm
- 5.3 ohm FC 1400 turns of 1.25mm copper wire
Below you can find a rather crude sketch of motor structure:
Here are some results from FEMM analysis:
I ran simmulations with 1010 steel as well as 416 steel (has slightly more carbon typical 0.15%) to see the differences.
1010 Steel Curve over 20mm and 12mm:
416 Steel Curve over 20mm and 12mm: (actually the curves are smoother had to lower resolution a bit because of my computer)
Magnetic gap:
AS it is, at 2.2 Amps we have 25W for the FC. I don't expect to have too much trouble with heat at this power. Test will tell tho, depending on how well the metal does the job of sinking the heat. The value predicted by FEMM lies around 1.6 Tesla. In reality i believe this value will be smaller 1.4-1.5 T. In tests i will drive the FC with 3 amps and see how much it heats up.
In this design the gap width is 1.5mm. Somewhat large, I'm thinking to add a 0.5mm thick copper ring right in the gap (yellow part from picture below). Now
it's true i have never seen a picture with a FC unit having a faraday ring and I'm not sure if it's necesary. I guess the FC itself has a role in that too.
I'm also making a 1mm gap variant (without copper ring) in hopes to get more flux density. The FEMM simmulation shows:
Here are some parts of the magnetic structure after machining:
***First i want to say I'm not sure if i should post this under Fullrange or Multiway. Since at this point, there is a high posibility of the need for a supertweeter i chose Multiway forums. I won't mind tho if moderators think it's more suited for Fullrange forums.
About 6 months ago, i started thinking about a DIY fieldcoil speaker. I know opinions vary quite a lot on this matter and so i will do my best to offer as much data as possible for things to be judged objectively. Since that time I have been talking with some fellow countrymen and audio enthusiasts about this project and these conversations helped me in making some of the design decisions. The work is still in progress and i hope your opinions and comments can help tune it to higher performance.
To begin, here are the basic aspects about this project:
- field coil underhung motor structure
- 12" diameter
- Wide range (up to 10kHz), hopefully fullrange (up to 20kHz)
- high efficiency
- to be used in BLH
My personal taste in sound is that i like it when it comes out of large radiating surfaces. Large SD, large horn mouths etc. I think it's a necesity when one tries to reach real, live music levels and at the same time keep a good response to instruments' attack, sustain and decay. This is the reason i chose 12 inch diameter. I would've liked 15" better but it would've been too difficult to make it wide range. Perphaps a future project.
Field Coil Motor Structure:
I have spent a lot of time looking for other field coil projects, for any information on FC design or about available products and i have to say there isn't
much out there. From the pictures of opened FC units i could see a basic shape of the pole pieces. I have to say this is amongst the first design issues i encountered, there isn't much freedom to design these pole pieces, not like the case with permanent magnets anyway.
The next thing one can notice is that the new FCs are low impedance type and this is easily understandable. I have decided that my field coil will also work with 12-15V supply.
Underhung design means thick top plate. Of course this will cause a drop in flux density in the gap. The compromise here i found to be between flux density value and voice coil excursion. Since this speaker will mostly be used horn loaded i sacrificied Xmax to make a thinner top plate. I use standard 1010 steel with a maximum of 0.13% carbon, the best i could get my hands on.
I ran simmulations in FEMM for different values of top plate thickness, FC's number of turns, dimension, wire diameter etc. Here are the results i stopped at:
- magnetic gap height: 12mm
- magnetic gap width: 1-1.5mm
- 5.3 ohm FC 1400 turns of 1.25mm copper wire
Below you can find a rather crude sketch of motor structure:
Here are some results from FEMM analysis:
I ran simmulations with 1010 steel as well as 416 steel (has slightly more carbon typical 0.15%) to see the differences.
1010 Steel Curve over 20mm and 12mm:
416 Steel Curve over 20mm and 12mm: (actually the curves are smoother had to lower resolution a bit because of my computer)
Magnetic gap:
AS it is, at 2.2 Amps we have 25W for the FC. I don't expect to have too much trouble with heat at this power. Test will tell tho, depending on how well the metal does the job of sinking the heat. The value predicted by FEMM lies around 1.6 Tesla. In reality i believe this value will be smaller 1.4-1.5 T. In tests i will drive the FC with 3 amps and see how much it heats up.
In this design the gap width is 1.5mm. Somewhat large, I'm thinking to add a 0.5mm thick copper ring right in the gap (yellow part from picture below). Now
it's true i have never seen a picture with a FC unit having a faraday ring and I'm not sure if it's necesary. I guess the FC itself has a role in that too.
I'm also making a 1mm gap variant (without copper ring) in hopes to get more flux density. The FEMM simmulation shows:
Here are some parts of the magnetic structure after machining:
Attachments
Weird wiring in Musical Fidelity phono preamp sections
- By mz543578854
- Solid State
- 26 Replies
Hi,
does anyone know what the two wires in the Musical Fidelity A1, B200, and other amps from that perdiod are supposed to be for?
If I am not completely mistaken, the cut track is just reconnected with one of them, and the other wire is just in parallel to another (uncut) track.
This is the 2nd amp I see this "in person" on now and searching the net for pics of open A1s etc. shows this is "normal".
The tracks are both coming from the MM/MC switch.
Any reasonable explanation?
Thanks,
Mo
does anyone know what the two wires in the Musical Fidelity A1, B200, and other amps from that perdiod are supposed to be for?
If I am not completely mistaken, the cut track is just reconnected with one of them, and the other wire is just in parallel to another (uncut) track.
This is the 2nd amp I see this "in person" on now and searching the net for pics of open A1s etc. shows this is "normal".
The tracks are both coming from the MM/MC switch.
Any reasonable explanation?
Thanks,
Mo
VSSA Lateral Mosfet Amplifier (lazycat) with EXICON
- By sercan85
- Solid State
- 86 Replies
VSSA AMPLIFIER WITH EXICON LATERAL MOSFET
PCB is available
PCB is available
Attachments
Safety Practices, General and Ultra-High Voltage
- By DrDeville
- Tubes / Valves
- 601 Replies
I want to live. 
In the interest of safety, I would like to collect whatever safety tips and practices this forum kindly and experienced members will share, so that all may benefit.
First, some warnings and disclaimers:
And please note that I have *no* amplifier hardware on hand, and will not for a while. This is a discussion only, and I will only be talking about doing stupid things, not actually doing them.
Okay, with that out of the way, I would like any tube equipment electrical safety advice you care to share, both in general, and for what I will classify (for the purposes of this discussion) as UltraHighVoltage--1000V to 1500V.
I'll start with what I think I know, and you can add more or correct me if I am wrong.
I can think of two basic rules of thumb--
From those rules of thumb, I can think of these specific practices:
In the interest of safety, I would like to collect whatever safety tips and practices this forum kindly and experienced members will share, so that all may benefit.
First, some warnings and disclaimers:
- Any voltage can be deadly.
- Amplifiers are dangerous--each person (me included) is responsible for deciding if they are willing to risk their life, and for ensuring that whatever information they receive is correct
- This forum and its members accept no responsibility for any death, injury or property damage that result from any of these suggestions--your safety is your own responsibility.
And please note that I have *no* amplifier hardware on hand, and will not for a while. This is a discussion only, and I will only be talking about doing stupid things, not actually doing them.
Okay, with that out of the way, I would like any tube equipment electrical safety advice you care to share, both in general, and for what I will classify (for the purposes of this discussion) as UltraHighVoltage--1000V to 1500V.
I'll start with what I think I know, and you can add more or correct me if I am wrong.
I can think of two basic rules of thumb--
- Make sure any charge-storing devices remain discharged while working on the equipment
- Avoid creating a circuit which would pass current through the heart.
From those rules of thumb, I can think of these specific practices:
- Put a drain load across all significant charge-storage devices (e.g. B+), and leave them there for the duration of your work--some devices can redevelop voltage if left unloaded.
- Verify that all charge-storing devices are discharged before starting work.
- Always work with only one hand--keep the other hand in your pocket.
- Use hook probe for secure connections and to avoid shorts.
- Wear rubber gloves and rubber soled shoes--no bare feet or socks.
- Make sure your design has the chassis safety grounded--connected to the ground wire of the power plug.
[/list=1]
Okay, what do you think about these practices, and what can you add?
One member spoke of a "bench isolating transformer". What is that, what does it do, and how is it installed/used?
Also, what extra design and usage practices apply to UltraHighVoltage (1000V to 1500V) electronics? I'm thinking about things like component choices, test procedures (standard DMMs are only rated to 600V), design practices (danger of arcing), etc.
Thanks for your attention and advice. Although I hope for courtesy, I'd rather be flamed figuratively than literally. 😉
Best,
George Ferguson