Nakamichi CD Player 3: "plays" fine, sound absolutely trashed, what do?
- By vladkorotnev
- Digital Source
- 23 Replies
Recently I've got a Nakamichi CD Player 3, the MusicBank kind. The seller said it was not opening the tray and thus playback was untested and they were giving it away for a decent discount. "Aight just a few new belts right?" — the famous last words before I turned my desk into a lab first time in a decade again.
Linking the service manual right here for those kindly playing along at home: ElektroTanya
So, indeed, first I went ahead and swapped the belts and lubricated all the plastic parts. One of the cogs in the optics lifter mechanism had some crud somehow make its way onto the rod so that had to be reseated.
Then it turned out the lever of the home position sensor of the stacker assy was broken off — so I bent the spring beneath it to account for that, finicky, but it works most of the time for now.
Powering it on revealed that sometimes it would glitch out, showing garbage on the screen or trying to spin the disc in reverse up to takeoff speeds. Tapping the +5V logic supply voltage regulator often fixed that by triggering a reset. So, reflowing that and the two transistors generating the ±5V supply for the DAC got the voltages steady and spot on within a few hundred mV of the designed value. (Those components went hot enough to slightly brown their surroundings on the board)
I took out a few caps at random on both the main and RF boards and they all matched the label, albeit I have to admit I didn't look at the ESR too much.
(Cue the Benny Hill chase soundtrack and footage of myself spending a whole day looking for the transistor shaped "turns-out-it's-a-fuse" that I've blown by shorting one of the caps by accident)
Then I plugged in my speakers and put in a pressed album and... the sound was absolutely trashed, as if only one bit of the DAC was working.
I assumed the DAC is broken, so I recorded a CD-R with a few sinewaves and a silent track, 30 seconds each.
And here's how the 1kHz sinewave, 50% FS looks like on the output:
Not quite 50%, not quite sinewave, but at least both channels are the same, so it's not like the DAC is faulty — I doubt both sides of it would've developed an exact same failure. It's more like something is loading garbage into it.
So I went on to play silence, and:
Definitely not silence either!
So, going on the path from the rear jacks backwards I traced along the following symptoms while playing the silence CD-R:
Easier done than said, I go ahead and try to look at the eye diagram on the RF input of the main board (while realizing the afterglow mode on my scope doesn't clear itself up over time), and this is what I see on a pressed CD:
Then I go onto a quest of re-lubricating the spindle motor bearing (a drop of IPA [not beer] into it, followed by some power tool oil), cleaning up the clamps, and attempting to make the eye diagram a tad better by spinning the EF SIGNAL knob, resulting in this on the pressed CD — that's as good ad I could get it:
But if it ain't broke, I fixed it! It won't really lock onto a CD-R anymore:
(in case of track 5-6, so 2.5-3min into the disc, it sometimes does play, but intermittently)
So now, the questions:
Thank you very much for your help!
Linking the service manual right here for those kindly playing along at home: ElektroTanya
So, indeed, first I went ahead and swapped the belts and lubricated all the plastic parts. One of the cogs in the optics lifter mechanism had some crud somehow make its way onto the rod so that had to be reseated.
Then it turned out the lever of the home position sensor of the stacker assy was broken off — so I bent the spring beneath it to account for that, finicky, but it works most of the time for now.
Powering it on revealed that sometimes it would glitch out, showing garbage on the screen or trying to spin the disc in reverse up to takeoff speeds. Tapping the +5V logic supply voltage regulator often fixed that by triggering a reset. So, reflowing that and the two transistors generating the ±5V supply for the DAC got the voltages steady and spot on within a few hundred mV of the designed value. (Those components went hot enough to slightly brown their surroundings on the board)
I took out a few caps at random on both the main and RF boards and they all matched the label, albeit I have to admit I didn't look at the ESR too much.
(Cue the Benny Hill chase soundtrack and footage of myself spending a whole day looking for the transistor shaped "turns-out-it's-a-fuse" that I've blown by shorting one of the caps by accident)
Then I plugged in my speakers and put in a pressed album and... the sound was absolutely trashed, as if only one bit of the DAC was working.
I assumed the DAC is broken, so I recorded a CD-R with a few sinewaves and a silent track, 30 seconds each.
And here's how the 1kHz sinewave, 50% FS looks like on the output:
Not quite 50%, not quite sinewave, but at least both channels are the same, so it's not like the DAC is faulty — I doubt both sides of it would've developed an exact same failure. It's more like something is loading garbage into it.
So I went on to play silence, and:
Definitely not silence either!
So, going on the path from the rear jacks backwards I traced along the following symptoms while playing the silence CD-R:
- Output filter OpAmp: just repeats the noise that the DAC sends into it, once the DAC shuts up there's no noise, so it's ruled out
- DAC: sends out the abomination on the second picture above on the L and R outs, and the input data line gets some blips of '1' bits at times, while I assume silence should be all '0'? Sure enough, shorting the data in to ground makes it shut up. The output waveform is somewhat like this:
- Digital filter / Resampler: Gets 1-2 of '1' bits every now and then on the data in line. Shorting the data in line to ground makes the whole downwards chain shut up, so I assume the Resampler is getting garbage data on the inputs.
- Sony DSP chip: the CRC incorrect flag line raises 1-2 times at a similar timing to those 1-2 '1' bits. (I don't have a second probe on the scope to compare)
- All the other frequencies seem to be spot on, aside from the PLL — it's constantly 0.2MHz too high, but locks on to the specced 4.2ish MHz just fine once the CD is spinning.
Easier done than said, I go ahead and try to look at the eye diagram on the RF input of the main board (while realizing the afterglow mode on my scope doesn't clear itself up over time), and this is what I see on a pressed CD:
Then I go onto a quest of re-lubricating the spindle motor bearing (a drop of IPA [not beer] into it, followed by some power tool oil), cleaning up the clamps, and attempting to make the eye diagram a tad better by spinning the EF SIGNAL knob, resulting in this on the pressed CD — that's as good ad I could get it:
But if it ain't broke, I fixed it! It won't really lock onto a CD-R anymore:
(in case of track 5-6, so 2.5-3min into the disc, it sometimes does play, but intermittently)
So now, the questions:
- Am I right in the assumption that the DF/DAC/OpAmp are likely all good?
- Could the Sony DSP chip fail in a way that it reads out the data fine but sends out garbage on the audio out? Are chips even likely to fail in the first place?
- Could it be the playhead having some crud get inside it and ruining the read out signal and should I replace that?
- ...Or am I dumb and those graphs just scream "I NEED A RECAP" about the main board? (The ESRs on the RF board were in spec as well so that's not it)
Thank you very much for your help!
Sonus Faber Cremona
I recently acquired a pair of these and like them for the most part but I find the top end a little too polite. They are lacking some bite and sparkle that I know exist. I realize that these are universally accepted as being laid back and forgiving speakers but if I can get a little more drive from the tweeters, these speakers would be that much more enjoyable.
All of the components are functioning properly.
Has anyone ever tweaked the crossovers in these? I came across a schematic but unfortunately no component values are indicated and I don’t how accurate the drawing is either. If a minor and reversible mod can be made in how the tweeter is attenuated, I would be willing to do some experimentation.
All of the components are functioning properly.
Has anyone ever tweaked the crossovers in these? I came across a schematic but unfortunately no component values are indicated and I don’t how accurate the drawing is either. If a minor and reversible mod can be made in how the tweeter is attenuated, I would be willing to do some experimentation.
GB4 for Pioneer Super Linear Headphone Amp PCB set?
- By EUVL
- Group Buys
- 49 Replies
Amazingly, after 5 years of GB3, I am still being asked for PCB sets.
https://www.diyaudio.com/community/...neer-super-linear-headphone-amplifier.328997/
You can see the latest successful build here :
https://www.diyaudio.com/community/threads/the-pioneer-super-linear-circuit.313163/post-7326342
We still have some boards left, enough to support 8 sets.
Minimum 5 subscribers / sets before we can cover our admin costs.
Same as before, each set consists of
2x PCB for Super Linear Amp
2x PCB for SL Current Source
2x PCB for Discrete Regulator Positive
2x PCB for Discrete Regulator Negative
1x PCB for SHPP Headphone Protection
1x PCB for CMoy Cross Feed (through hole version)
Price will be 500 HKD all inclusive (FOB).
Please enter your interest below in a running list.
Minimum 5 sets, maximum 8 sets.
Thank you for your interest,
Patrick
Frequency drift in Sony tuner(s)
- By atsirik
- Analogue Source
- 0 Replies
Some time ago I had posted a thread about adjusting a St-S370 Sony tuner. At that time, the unit would show "100.00MHz" and in reality it would "tune" to 98.50MHz, which I had "fixed" with NULL adjustment. Unfortunately after some months of not using the unit the same problem re-appeared: the unit would not light the "TUNED" indication, no stereo indication, no auto-tuning and no RDS. I had read that gravity sometimes was the cause, but I realized that in my case it was not the problem (as this time i had to turn it even "lower" to re-align). Also it was VERY temperature sensitive (on a hot evening it would not "TUNE" or auto-tune, if it was adjusted the previous cold morning).
The solution (so far) was found by accident when trying to solve a problem of another Sony tuner (St-sa5es this time). I came across a german page in which the solution was described as being a problematic capacitor soldered inside the legs of the T252 (NULL adjustment can). When I unsoldered it to access the capacitor, and tried to remove the metal can cover, the capacitor was desintegrating in my hands, and in the end it broke literally in dust, with a simple "touch" of a plastic screwdriver. I believe breaking it is the best way to remove it as the plastic of the component is also very old and sensitive to crack while removing the cover. This means I didn't have the chance to roughly measure the actual value of that capacitor, so I used 2x47pF C0G capacitors in parallel (I tried to be close to the 91 pF, the value mentioned in that webpage). I soldered the capacitors outside the can (in fact I soldered on top of the board, across a resistor which connects to the same pins where the capacitor was soldered, as I wanted to experiment with freezing and heating the capacitors). After that, a very slight NULL adjustment was needed (which indicated the faulty capacitor's value was not very different than the 94pF I used) and now everything seems to work as it should. No drift of frequency even when using hairdryer and then freezer on the capacitor (and the T252 can). I am now waiting to see what will happen in the long run, but I believe this is the definite fix, as before I had slight problems from day two (drifts when using the unit cold until it heated a bit and would "TUNE").
And now a bit of information I wanted to share about a ST-SA5ES I bought, which would not auto-tune or display RDS data. The first thing to try was again NULL adjustment. I then realized that the IFT272 (IF transformer which is the adjusting component in this unit) was stripped and it was impossible to move up or down the ferrite core by turning it! Also there are no specs anywhere on the internet, so my only chance was to buy a new plastic frame and wind the transformer myself, following the winding of the original).
So I ordered from aliexpress and empty container for the "stripped" can. The most relevant I could find was "K175 High Frequency Radio Transmitter Receiver Adjustable Inductance Coil Skeleton Kit Accessories" (5 "floors" in bobbin, 7+7x12 cm, core 3.2x5 , it is a bit taller than original).
I have to note that this has 5 pins (3+2) so I had to insert an extra pin on one side (original has 3+3 pins on)
How to wind it: (I used original thin wire which was unwound the reverse order from the instructions below):
(When I say "floor" I mean those showed on the next pic, where I number 5 is the topmost and 1 the lowest - NOTE: the pic below which I found has 4 "floors" instead of 5):
Side1 (with pins 1 to 3 from left to write): solder fine wire to left pin 1 and wind to the 3rd floor (middle of 5 floors) clockwise (looking from top) 4 times, then solder to middle pin 2, wind another 4 turns again to floor 3 and solder to the right pin 3.
Side2 (pins 3,4,5): solder fine wire to left pin 3 and wind 3 full turns clockwise (looking from top) to the lowest (1st floor), then another 3 turns to the 2nd floor, another 3 turns to the 4th floor (we skip 3rd floor) and finally 4 turns to the top (5th) floor, then solder to middle pin 4, then wind another 3 turns to the lowest 1st floor, 3 turns to the 2nd floor, 3 to the 4th and 4 turns to the 5th "floor", then solder to right pin 5.
After doing this, without using the external metal can enclosure, I could "tune" the discriminator with the iron core near the bottom of the bobbin (I used the new aliexpress core, not the smaller original). After adding the metal enclosure, the tuning point was close to the top. (When adding the supplied magnet cup, I could not fine tune as it was a over the top of the bobbin and I was out of turns - so I didn't use magnet cup).
Having done all that, I was able to get back tuning (TUNED and STEREO indications) and RDS recognition, and then I realized the tuner was 100kHz out (100.4 on display was actually 100.3), which I corrected very easily using the method in service manual (adjusting IFT251 to zero across the resistor that connects to pins 7 and 10 of chip 251).
As I checked it is also temperature stable, 3 weeks from adjustment nothing has "drifted", and also auto tuning works normally.
Sorry for the very long post, I just wanted to explain how to wind a "compatible" IFT272 as there is zero information on that on the internet (and this type of circuit is used in most top of the line Sony tuners - 707ES, 770ES etc.) I thought someone might need it in the future... And I wanted also to share the problem with temperature stability, which I think occurs quite frequently as those tuners are now old and many used similar cans from the same manufacturers so they might experience the same problems sooner or later.
The solution (so far) was found by accident when trying to solve a problem of another Sony tuner (St-sa5es this time). I came across a german page in which the solution was described as being a problematic capacitor soldered inside the legs of the T252 (NULL adjustment can). When I unsoldered it to access the capacitor, and tried to remove the metal can cover, the capacitor was desintegrating in my hands, and in the end it broke literally in dust, with a simple "touch" of a plastic screwdriver. I believe breaking it is the best way to remove it as the plastic of the component is also very old and sensitive to crack while removing the cover. This means I didn't have the chance to roughly measure the actual value of that capacitor, so I used 2x47pF C0G capacitors in parallel (I tried to be close to the 91 pF, the value mentioned in that webpage). I soldered the capacitors outside the can (in fact I soldered on top of the board, across a resistor which connects to the same pins where the capacitor was soldered, as I wanted to experiment with freezing and heating the capacitors). After that, a very slight NULL adjustment was needed (which indicated the faulty capacitor's value was not very different than the 94pF I used) and now everything seems to work as it should. No drift of frequency even when using hairdryer and then freezer on the capacitor (and the T252 can). I am now waiting to see what will happen in the long run, but I believe this is the definite fix, as before I had slight problems from day two (drifts when using the unit cold until it heated a bit and would "TUNE").
And now a bit of information I wanted to share about a ST-SA5ES I bought, which would not auto-tune or display RDS data. The first thing to try was again NULL adjustment. I then realized that the IFT272 (IF transformer which is the adjusting component in this unit) was stripped and it was impossible to move up or down the ferrite core by turning it! Also there are no specs anywhere on the internet, so my only chance was to buy a new plastic frame and wind the transformer myself, following the winding of the original).
So I ordered from aliexpress and empty container for the "stripped" can. The most relevant I could find was "K175 High Frequency Radio Transmitter Receiver Adjustable Inductance Coil Skeleton Kit Accessories" (5 "floors" in bobbin, 7+7x12 cm, core 3.2x5 , it is a bit taller than original).
I have to note that this has 5 pins (3+2) so I had to insert an extra pin on one side (original has 3+3 pins on)
How to wind it: (I used original thin wire which was unwound the reverse order from the instructions below):
(When I say "floor" I mean those showed on the next pic, where I number 5 is the topmost and 1 the lowest - NOTE: the pic below which I found has 4 "floors" instead of 5):
Side1 (with pins 1 to 3 from left to write): solder fine wire to left pin 1 and wind to the 3rd floor (middle of 5 floors) clockwise (looking from top) 4 times, then solder to middle pin 2, wind another 4 turns again to floor 3 and solder to the right pin 3.
Side2 (pins 3,4,5): solder fine wire to left pin 3 and wind 3 full turns clockwise (looking from top) to the lowest (1st floor), then another 3 turns to the 2nd floor, another 3 turns to the 4th floor (we skip 3rd floor) and finally 4 turns to the top (5th) floor, then solder to middle pin 4, then wind another 3 turns to the lowest 1st floor, 3 turns to the 2nd floor, 3 to the 4th and 4 turns to the 5th "floor", then solder to right pin 5.
After doing this, without using the external metal can enclosure, I could "tune" the discriminator with the iron core near the bottom of the bobbin (I used the new aliexpress core, not the smaller original). After adding the metal enclosure, the tuning point was close to the top. (When adding the supplied magnet cup, I could not fine tune as it was a over the top of the bobbin and I was out of turns - so I didn't use magnet cup).
Having done all that, I was able to get back tuning (TUNED and STEREO indications) and RDS recognition, and then I realized the tuner was 100kHz out (100.4 on display was actually 100.3), which I corrected very easily using the method in service manual (adjusting IFT251 to zero across the resistor that connects to pins 7 and 10 of chip 251).
As I checked it is also temperature stable, 3 weeks from adjustment nothing has "drifted", and also auto tuning works normally.
Sorry for the very long post, I just wanted to explain how to wind a "compatible" IFT272 as there is zero information on that on the internet (and this type of circuit is used in most top of the line Sony tuners - 707ES, 770ES etc.) I thought someone might need it in the future... And I wanted also to share the problem with temperature stability, which I think occurs quite frequently as those tuners are now old and many used similar cans from the same manufacturers so they might experience the same problems sooner or later.
High power GU46 SE amplifier - help with certain issues
- By ClassZ
- Tubes / Valves
- 63 Replies
Attachments
Power amp OUTPUT STAGE measurements shootout
- By peufeu
- Solid State
- 561 Replies
Let's try new ways to measure the distortion of power amp output stages, with inspiration from the Gedlee metric. This is the concept:
How it works
The DUT, output stage under test (here, the usual push pull) has its bases driven and biased. Its output is set to 0V at DC.
Current is injected into its output by the two drive amplifiers on the right, via the associated resistors.
LF amplifier channel outputs a large low frequency signal (0.5-1A, 40Hz) which sets the "DC" operating point of the DUT, basically the current in both transistors.
HF amplifier channel outputs a high frequency low amplitude current (few mA, 20-40 kHz), which is injected into the output stage.
A bunch of high performance instrumentation amplifiers (AD8421) monitor voltage in interesting places:
- output voltage
- output current (for verification)
- emitter resistors to measure current through both transistors
- base resistors to measure base current
- Vbe, if needed
Implementation
Control: STM32G0 (12 bit ADC), and 4 channel 12 bit I2C DAC, with amplifiers.
Current drive amp: Modulus-86 with DC servo deactivated on one channel.
DUT Base drive: 2 channel TPA6120 composite.
The base drive amps and the high current drive amp are controlled at DC by the micro and DAC, and AC coupled with the soundcard, so they can output DC plus AC signal.
DUT bias current can be set either directly (if both bases are driven) or via the usual Vbe multiplier, which is controller by an optocoupler. In both cases, the micro can set and measure the bias current.
Soudcard: Steinberg UR-44C (4 out, 6 in, 24b-192k)
Power supply: 2x programmable KD3005P 30V 5A
Since all parameters are controlled, 4-quadrant testing is possible: for example the output stage can be driven by a sine wave, and its output current by a phase shifted sine wave, which can emulate any reactive load impedance. Additionally, the power supplies are controlled, so behavior can be investigated over the whole Vce/Vds range.
The whole thing is scripted with python.
How it works
The DUT, output stage under test (here, the usual push pull) has its bases driven and biased. Its output is set to 0V at DC.
Current is injected into its output by the two drive amplifiers on the right, via the associated resistors.
LF amplifier channel outputs a large low frequency signal (0.5-1A, 40Hz) which sets the "DC" operating point of the DUT, basically the current in both transistors.
HF amplifier channel outputs a high frequency low amplitude current (few mA, 20-40 kHz), which is injected into the output stage.
A bunch of high performance instrumentation amplifiers (AD8421) monitor voltage in interesting places:
- output voltage
- output current (for verification)
- emitter resistors to measure current through both transistors
- base resistors to measure base current
- Vbe, if needed
Implementation
Control: STM32G0 (12 bit ADC), and 4 channel 12 bit I2C DAC, with amplifiers.
Current drive amp: Modulus-86 with DC servo deactivated on one channel.
DUT Base drive: 2 channel TPA6120 composite.
The base drive amps and the high current drive amp are controlled at DC by the micro and DAC, and AC coupled with the soundcard, so they can output DC plus AC signal.
DUT bias current can be set either directly (if both bases are driven) or via the usual Vbe multiplier, which is controller by an optocoupler. In both cases, the micro can set and measure the bias current.
Soudcard: Steinberg UR-44C (4 out, 6 in, 24b-192k)
Power supply: 2x programmable KD3005P 30V 5A
Since all parameters are controlled, 4-quadrant testing is possible: for example the output stage can be driven by a sine wave, and its output current by a phase shifted sine wave, which can emulate any reactive load impedance. Additionally, the power supplies are controlled, so behavior can be investigated over the whole Vce/Vds range.
The whole thing is scripted with python.
Leaking electrolytic capacitors nearly destroyed my old preamp - A cautionary tale
About 5 years ago I had a problem with my Rowland Consummate preamp. DC on the outputs.
I contacted Rowland about the problem. The preamp has a separate power supply enclosure, and the power supply measured within spec, so it was assumed the problem was in the potted gain modules, which were no longer available. The preamp went into storage.
About 3 years ago Jeff was able to find some old gain modules, which I gladly bought. Sadly, the problem that seemed to go away came back soon afterwards. The preamp went into storage again.
Since I started diy about 10 years, I am (very, very) slowly understanding how some simple circuits works. Also, reading the experiences of other diyers has been great to gain a better understanding of what does what, and why and how. Anyway, I had a feeling the electrolytic capacitors (1993 vintage) might be the cause of the problem. I opened up both enclosures to take detailed photos to find out the specifications of the original caps used. I needed this if I was going to find replacement capacitors (there is no service manual or schematic available to my knowledge).
What I found when I zoomed in on one of the photo's in particular was what I assumed was a leaking capacitor.
Long story short, yes there were a few leaking capacitors. They had been leaking electrolyte and it looked like they had damaged a few tracks on the pcb.
Knowing I was out of my depth and not wanting to damage such a rare and beautiful preamp, I found a technician with lots of experience. He removed all the electrolytic caps from both pcbs and was able to clean up the boards for me.
With the aid of photos sent to me by someone who had just recapped his own Consummate, my technician was able to reconstruct the damaged tracks of the amplifier pcb and replaced all the caps for me.
After 5 years, I am once again listening to a great preamp!
If you have vintage gear, please check for leaking electrolytic capacitors. Don't wait until the leaking electrolyte eats away the tracks and causes damage that cannot be repaired
I contacted Rowland about the problem. The preamp has a separate power supply enclosure, and the power supply measured within spec, so it was assumed the problem was in the potted gain modules, which were no longer available. The preamp went into storage.
About 3 years ago Jeff was able to find some old gain modules, which I gladly bought. Sadly, the problem that seemed to go away came back soon afterwards. The preamp went into storage again.
Since I started diy about 10 years, I am (very, very) slowly understanding how some simple circuits works. Also, reading the experiences of other diyers has been great to gain a better understanding of what does what, and why and how. Anyway, I had a feeling the electrolytic capacitors (1993 vintage) might be the cause of the problem. I opened up both enclosures to take detailed photos to find out the specifications of the original caps used. I needed this if I was going to find replacement capacitors (there is no service manual or schematic available to my knowledge).
What I found when I zoomed in on one of the photo's in particular was what I assumed was a leaking capacitor.
Long story short, yes there were a few leaking capacitors. They had been leaking electrolyte and it looked like they had damaged a few tracks on the pcb.
Knowing I was out of my depth and not wanting to damage such a rare and beautiful preamp, I found a technician with lots of experience. He removed all the electrolytic caps from both pcbs and was able to clean up the boards for me.
With the aid of photos sent to me by someone who had just recapped his own Consummate, my technician was able to reconstruct the damaged tracks of the amplifier pcb and replaced all the caps for me.
After 5 years, I am once again listening to a great preamp!
If you have vintage gear, please check for leaking electrolytic capacitors. Don't wait until the leaking electrolyte eats away the tracks and causes damage that cannot be repaired
Needs advice on how to achieve wireless PC audio to mixer
- By TanMason
- PA Systems
- 7 Replies
Hi,
Here is what i am trying to achieve. You may refer to the layout map.
Host is using wireless mic connected to mixer and usb condenser mic connected to PC for zoom streaming.
1. Is there a way to stream PC sound(Music etc) wirelessly to the mixer?
2. Is there a way to concurrently output the usb condenser mic to PC and mixer(wirelessly).
*USB condenser mic has a headphone monitoring port, can i perhaps use that as a way? or recommend a condenser mic that can accomplish that is fine as well(Budget below 300USD)
USB condenser mic BOYA BY-PM500
Wireless mic lav mic(Mini XLR) to transmitter pack
Thank You in advance. Do ask if you need more information. Not an expert in AV field, will try my best to explain as clearly as i can haha.
Here is what i am trying to achieve. You may refer to the layout map.
Host is using wireless mic connected to mixer and usb condenser mic connected to PC for zoom streaming.
1. Is there a way to stream PC sound(Music etc) wirelessly to the mixer?
2. Is there a way to concurrently output the usb condenser mic to PC and mixer(wirelessly).
*USB condenser mic has a headphone monitoring port, can i perhaps use that as a way? or recommend a condenser mic that can accomplish that is fine as well(Budget below 300USD)
USB condenser mic BOYA BY-PM500
Wireless mic lav mic(Mini XLR) to transmitter pack
Thank You in advance. Do ask if you need more information. Not an expert in AV field, will try my best to explain as clearly as i can haha.
Orchard Audio Demo Room in Rockaway, NJ - Grand Opening - October 21st 2023
- By orchardaudio
- Vendor's Bazaar
- 0 Replies
Time: October 21st, Noon to 4pm
Location: 176 Franklin Ave, Rockaway, NJ 07866
Come listen to some great music and get 10% off for coming to check out our demo room.
If you have your own favorite songs, bring them on a flash drive.
The current setup is
Source: PecanPi+ Streamer
Amplifier: Starkrimson Stereo Ultra
Speakers: Soundfield Audio M1V2
Cables: Triode Wire Labs
Room Treatment: GIK Acoustics
If you use FB please RSVP here: https://www.facebook.com/events/850175626681294/
Location: 176 Franklin Ave, Rockaway, NJ 07866
Come listen to some great music and get 10% off for coming to check out our demo room.
If you have your own favorite songs, bring them on a flash drive.
The current setup is
Source: PecanPi+ Streamer
Amplifier: Starkrimson Stereo Ultra
Speakers: Soundfield Audio M1V2
Cables: Triode Wire Labs
Room Treatment: GIK Acoustics
If you use FB please RSVP here: https://www.facebook.com/events/850175626681294/
Crest Audio CA9 repair help- Who added these resistors?
- By Zolof911
- Solid State
- 0 Replies
Attachments
Help understanding balance circuit in Kenwood KR-5600, and how I can replace the pot
- By bdondo
- Solid State
- 3 Replies
I have a Kenwood KR-5600 receiver, which was my dad's while I was growing up. I'm trying to fix it up as it's one of the few things I have of his. The balance pot's shaft was broken off a long time ago, probably by me as a kid, and it's proving to be the hardest replacement to find.
It's 200K, 17mm wide, 30mm shaft length, knurled, and linear taper. Going by the part number description from Bourns, I believe the theoretical replacement part number would be PDB181-K230K-204B (or PDB181-K430K-204B would work too). As far as I can tell, this doesn't exist, and I haven't found anything like it online anywhere.
So I thought maybe I could use a 100K pot instead. My circuit analysis skills faded long ago, but I tried to figure out what effect changing the pot would have on the amplitude of the signal reaching the first transistor in the power amp. I'm hoping someone can chime in and tell me if using a 100K pot instead of 200K pot would be ok. The relevant part of the circuit is below:
I tried drawing a simplified schematic of one channel here, but I'm not totally sure I got it right. In this sketch I'm replacing the 100K volume control with two 50K resistors, and setting the balance to the center, so it's 100K on each side.
I roughly calculated the resistance of all the resistors to the right of the first 50K resistor (from the volume pot) to be about 25KOhms (I assumed the capacitors could be replaced with shorts for this calculation, based on fuzzy recollection from school 25 years ago). If I replace the balance pot with a 100K pot, and set it to center so that only 50K is used, then this resistance becomes 20KOhms.
I also simulated the circuit on circuitlab (before my free trial ran out) and using 1KHz, 1V (peak) signal in, the signal at the base of the transistor is 317mV (peak) using the 200K pot. With the 100K pot, it drops 14.5% to 271mV (peak).
I'm not very confident that my simplified circuit is correct, or if these differences in resistance and voltage I've calculated/simulated are significant. I was thinking they aren't a big deal, but then I read about balance controls in Douglas Self's Small Signal Audio Design book, and now I'm not so sure. It seems that these values could be important in maintaining the right amount of noise, dB loss at center position, etc., but I'm also not sure I fully understand what I just read in that book.
Any help would be greatly appreciated!
It's 200K, 17mm wide, 30mm shaft length, knurled, and linear taper. Going by the part number description from Bourns, I believe the theoretical replacement part number would be PDB181-K230K-204B (or PDB181-K430K-204B would work too). As far as I can tell, this doesn't exist, and I haven't found anything like it online anywhere.
So I thought maybe I could use a 100K pot instead. My circuit analysis skills faded long ago, but I tried to figure out what effect changing the pot would have on the amplitude of the signal reaching the first transistor in the power amp. I'm hoping someone can chime in and tell me if using a 100K pot instead of 200K pot would be ok. The relevant part of the circuit is below:
I tried drawing a simplified schematic of one channel here, but I'm not totally sure I got it right. In this sketch I'm replacing the 100K volume control with two 50K resistors, and setting the balance to the center, so it's 100K on each side.
I roughly calculated the resistance of all the resistors to the right of the first 50K resistor (from the volume pot) to be about 25KOhms (I assumed the capacitors could be replaced with shorts for this calculation, based on fuzzy recollection from school 25 years ago). If I replace the balance pot with a 100K pot, and set it to center so that only 50K is used, then this resistance becomes 20KOhms.
I also simulated the circuit on circuitlab (before my free trial ran out) and using 1KHz, 1V (peak) signal in, the signal at the base of the transistor is 317mV (peak) using the 200K pot. With the 100K pot, it drops 14.5% to 271mV (peak).
I'm not very confident that my simplified circuit is correct, or if these differences in resistance and voltage I've calculated/simulated are significant. I was thinking they aren't a big deal, but then I read about balance controls in Douglas Self's Small Signal Audio Design book, and now I'm not so sure. It seems that these values could be important in maintaining the right amount of noise, dB loss at center position, etc., but I'm also not sure I fully understand what I just read in that book.
Any help would be greatly appreciated!
59.0 BILLION images searched at Tineye - what manufacturer is this?
This is from the biasing board for a Willsenton R8 amplifier. Ostensibly it's a wirewound rheostat.
First, I'm trying to identify the company.
Second, looking for suitable replacement (preventive, not needing replacement at this time although a few folks HAVE had issues with them. Willsenton just sends them new boards).
Did I search the web? Yep. Pages upon pages of logos.
Did I contact the company, Willsenton? Not yet. Too easy.
Thanks in advance.
First, I'm trying to identify the company.
Second, looking for suitable replacement (preventive, not needing replacement at this time although a few folks HAVE had issues with them. Willsenton just sends them new boards).
Did I search the web? Yep. Pages upon pages of logos.
Did I contact the company, Willsenton? Not yet. Too easy.
Thanks in advance.
![PXL_20230919_214629906[1].jpg](/community/data/attachments/1122/1122935-f6aefa9d067d139741fde019d11737fe.jpg?hash=9q76nQZ9E5)
McIntosh MC2505 Volume Pot Needed
- By ampexperts
- Parts
- 6 Replies
Customer said his 2505 took a fall. The pots are smashed in. I was able to repair one of them, but the other one has a crash in the diecast metal thread assembly which separated from the part of the diecast that attaches to front of pot.
McIntosh p/n 134-207. 250K. Shaft is 2-5/8" long.
Anyone got one? Or the diecast part so I can fix this one?
McIntosh p/n 134-207. 250K. Shaft is 2-5/8" long.
Anyone got one? Or the diecast part so I can fix this one?
For Sale Ellipticor tweeters and revelator midranges
- By vassilis1984
- Swap Meet
- 2 Replies
Attachments
1625/807 UNSET PP review
- By jderimig
- Tubes / Valves
- 12 Replies
Below is an LTSpice model of a prospective PP amp with 1625 using UNSET topology. Of course the real amp will have adjustable bias and grid and screen resistors etc but first I just wanted to rough this out. Input will be from a balanced source. This model is biased for the outputs to remain in class A and develops about 20W at clipping. Spice says it seems to want 10-11K primary impedance transformers at this plate voltage of around 400V. Any major flaws? Other things to consider?
