Why does it work? Crossover with RF ferrite (wires) and 10nF polystyrene (bypass)
- By maty tinman
- Multi-Way
- 69 Replies
I have a question to ALL.
Two years ago I had cheap tweaks with my KEF Q100 coaxial speaker. It was trial and error.
[comment]
[/comment]
1ª Why when I add a RF ferrite to the woofer wires I have more bass and faster?
2ª Why when I add a RF ferrite to the twitter wires I have more too much HF?
3ª Why do bypass with a small 10nF polystyrene the HF are less shrill and more pleasing despite being more detailed than before?
I have my hypothesis and I have read others but I still do not have it clear. Please, serious answers.
Two years ago I had cheap tweaks with my KEF Q100 coaxial speaker. It was trial and error.
[comment]
[/comment]
1ª Why when I add a RF ferrite to the woofer wires I have more bass and faster?
2ª Why when I add a RF ferrite to the twitter wires I have more too much HF?
3ª Why do bypass with a small 10nF polystyrene the HF are less shrill and more pleasing despite being more detailed than before?
I have my hypothesis and I have read others but I still do not have it clear. Please, serious answers.
Bruno Putzey's G-Word with Hypex HPR and HNR 12 regs
- By Bas Horneman
- Swap Meet
- 2 Replies
Attachments
noname loudspeaker – a polite request for help in identifying
Hello,
I have a polite request for help in identifying loudspeakers that I bought "for a penny" 🙂. I bought them without the ability to check/look inside, mainly due to the rubber speaker suspension and optically good condition of the enclosures. Maybe someone had something "like this" once in his hands and knows what it is ?
Going to the point:
- woofer: 16cm in diameter, magnet 9cm in diameter and 1.8cm high, rubber suspension (with inscription SR161/2), holes in the basket sealed with factory fabric, dc resistance approx. 3.6ohm, poorly visible designation CKS 7x87-378 U3 on the magnet foot (not all signs readable), the speakers were originally mounted using a black tar-like sealing agent:
- branching filter: designation 001160 30A6, Frako ETF 7,5uF and 15uF capacitors, 9217-037 small coil and a second one in the back, wound using a trafo core and epoxy-impregnated (with partially illegible designation xxx201), resistor 8,2ohm:
- tweeter: absent, only 12x12 cm hole with 10x10cm mount remained;
- housing: 40x22x20cm, made solidly, speaker fastenings made using M4 threaded rosettes pressed from underneath into the front panel:
- connections: admittedly with the proud name "Magnat" but according to me non-original, quite crap (especially on the side of soldering - or rather its absence - see how "expertly" you can connect the wires), their holes in the housing seem not to be factory-cut:
- no company sign, no other indications.
I have tried but unfortunately nowhere did I find any information about CKS speakers. I am thinking about restoring these loudspeakers, which is why I are looking for some basic information.
Best regards,
Pawel
I have a polite request for help in identifying loudspeakers that I bought "for a penny" 🙂. I bought them without the ability to check/look inside, mainly due to the rubber speaker suspension and optically good condition of the enclosures. Maybe someone had something "like this" once in his hands and knows what it is ?
Going to the point:
- woofer: 16cm in diameter, magnet 9cm in diameter and 1.8cm high, rubber suspension (with inscription SR161/2), holes in the basket sealed with factory fabric, dc resistance approx. 3.6ohm, poorly visible designation CKS 7x87-378 U3 on the magnet foot (not all signs readable), the speakers were originally mounted using a black tar-like sealing agent:
- branching filter: designation 001160 30A6, Frako ETF 7,5uF and 15uF capacitors, 9217-037 small coil and a second one in the back, wound using a trafo core and epoxy-impregnated (with partially illegible designation xxx201), resistor 8,2ohm:
- tweeter: absent, only 12x12 cm hole with 10x10cm mount remained;
- housing: 40x22x20cm, made solidly, speaker fastenings made using M4 threaded rosettes pressed from underneath into the front panel:
- connections: admittedly with the proud name "Magnat" but according to me non-original, quite crap (especially on the side of soldering - or rather its absence - see how "expertly" you can connect the wires), their holes in the housing seem not to be factory-cut:
- no company sign, no other indications.
I have tried but unfortunately nowhere did I find any information about CKS speakers. I am thinking about restoring these loudspeakers, which is why I are looking for some basic information.
Best regards,
Pawel
Turning a weird headphones amp into a preamp
- By Fergutor
- Analog Line Level
- 11 Replies
I was about to make the famous Rod Elliott's project 97 to drive a TDA7379 (that I'm yet to do) when I remembered I made a headphones amplifier years ago (it was never used apart from me checking it worked) by joining 2 different schematics for different uses, so I thought: could I turn that one into a preamplifier? What should I modify?
1-Do you think changing the output components values into the ones that P97 have is enough (6r8 to 100r, 220uF to 10uF and 10k to 100k)?
2-Should I remove that 1uF between the inverting input opamp and the Baxandall tone?
3-What about input components, should I modify those?
4-The headphones amplifier was made to use a single 9v PS, do you think it's possible to modify it to use a dual supply? Or it isn't necessary (I think it isn't)?
Or should I leave it as it is?
Or for some other reason it isn't suitable?
Or should I just make the P97 and stop bothering!? 😀
Here are the schematics:
The weird headphones amp:
The P97 just in case:
The TDA7379 shcematic from the datasheet (don't know yet what to modify ) :
1-Do you think changing the output components values into the ones that P97 have is enough (6r8 to 100r, 220uF to 10uF and 10k to 100k)?
2-Should I remove that 1uF between the inverting input opamp and the Baxandall tone?
3-What about input components, should I modify those?
4-The headphones amplifier was made to use a single 9v PS, do you think it's possible to modify it to use a dual supply? Or it isn't necessary (I think it isn't)?
Or should I leave it as it is?
Or for some other reason it isn't suitable?
Or should I just make the P97 and stop bothering!? 😀
Here are the schematics:
The weird headphones amp:
The P97 just in case:
The TDA7379 shcematic from the datasheet (don't know yet what to modify ) :
Drive Board
Hi All. I have a Star Sound 6500 amp. I stand to be corrected but I think it is a copy of the Atomic 5K.
Another tech tried to repair the amp but just messed it up. I got the amp with the drive board missing. the guy damaged a few tracks to the drive board and also broke the vias. I was able to trace most of the track but just cannot for the life of me trace just one track. this is on the center pins the one that carries the voltages. Now on the drive board this is pin 6 that goes the the op amp U4 on pin 7.
Now I need to find out on the amp board where does pin 6 go to. Does it join with pin as it looks like it does.
Another tech tried to repair the amp but just messed it up. I got the amp with the drive board missing. the guy damaged a few tracks to the drive board and also broke the vias. I was able to trace most of the track but just cannot for the life of me trace just one track. this is on the center pins the one that carries the voltages. Now on the drive board this is pin 6 that goes the the op amp U4 on pin 7.
Now I need to find out on the amp board where does pin 6 go to. Does it join with pin as it looks like it does.
Pioneer M-22 class A amp mistake in service manual?
- By jeromach
- Solid State
- 52 Replies
I recently gave this amp a full rebuild, having replaced all caps (except the large filter caps), all transistors and the four trimpots.
Now the manual states the DC offset needs to be adjusted to 80mV.
I have a hard time believing that to be correct, can it be that it is just a mistake in the service manual?
I now just ignored it and adjusted it to 0mV and it plays fine.
There is just an - I assume - unrelated difference in temperature at the right and left side of the amp, the left side heat sink warms up to about 65 degrees, while the right side goes up to around 55 degrees.
The bias is adjusted to 850mV according to the manual and it stays stable at both sides.
What would cause that relatively large difference? The power supply stage only at the left side of the amp?
Some pics of the rebuild;
Now the manual states the DC offset needs to be adjusted to 80mV.
I have a hard time believing that to be correct, can it be that it is just a mistake in the service manual?
I now just ignored it and adjusted it to 0mV and it plays fine.
There is just an - I assume - unrelated difference in temperature at the right and left side of the amp, the left side heat sink warms up to about 65 degrees, while the right side goes up to around 55 degrees.
The bias is adjusted to 850mV according to the manual and it stays stable at both sides.
What would cause that relatively large difference? The power supply stage only at the left side of the amp?
Some pics of the rebuild;
Push-Pull EL84 amplifier
- By Giulio28
- Tubes / Valves
- 77 Replies
Hi, i want to build a simple el84 pp amp. I have a 8k output transformer (without UL) 2 el84 and a ecc82. Is this a good schematic?
Has the ecc82 a proper gain for a input a .5Vrms at full power? If i have 2 nputs, one a CD player, and the other is a Computer, which has a minor output, how can i have a equal level at the same volume?
Thanks for any ansower and sorry for any grammatical error, i'm an italian student and i don't know english very well.
Has the ecc82 a proper gain for a input a .5Vrms at full power? If i have 2 nputs, one a CD player, and the other is a Computer, which has a minor output, how can i have a equal level at the same volume?
Thanks for any ansower and sorry for any grammatical error, i'm an italian student and i don't know english very well.
Polymer vs. electrolytic caps in phono pre
Looking to change out cheap electrolytics in an ART DJ Pre II phono preamp and wondering if there are opinions on whether switching to polymers or just using better electrolytics would be best choice.
I like the sound of the budget ART and willing to experiment with a cap change to see if it can elevate the already decent performance. Whether or not this is a wise thing to spend a similar amount on caps as the whole unit costs is not really for debate.
I have only come across one user who switched out some of the cheap electrolytics with some Panasonic OS-CON polymers and commented "sounds really good now".
A very knowledgeable hobbyist has suggested the polymers in such a circuit might sound cold and dry so seeking more opinions on whether this might be the case.
In the end, I realize the only way to find out is to do the swap but before I commit I would appreciate any expert opinions on polymer vs. electrolytic choice.
I like the sound of the budget ART and willing to experiment with a cap change to see if it can elevate the already decent performance. Whether or not this is a wise thing to spend a similar amount on caps as the whole unit costs is not really for debate.
I have only come across one user who switched out some of the cheap electrolytics with some Panasonic OS-CON polymers and commented "sounds really good now".
A very knowledgeable hobbyist has suggested the polymers in such a circuit might sound cold and dry so seeking more opinions on whether this might be the case.
In the end, I realize the only way to find out is to do the swap but before I commit I would appreciate any expert opinions on polymer vs. electrolytic choice.
An interesting thing happened while gluing a voice coil..
On over-excursion of a woofer(s) run in Dipole, there was a loud "POP"..
Turns-out it was the cone hitting the VC leads which were sloppy-large: plenty of VC lead, but the natural bend down to the VC sagged to low: on recovery the cone slams into that "sag" from the VC lead.
Fortunately there is enough lead there to sort of "lift and separate" (like a bra on an old woman
) and still allow for more than enough excursion (even when pushing well beyond the gap).
My solution then was to put some felt tabs on the frame (inside/underside) near the driver's terminals and "lift/separate" them to those felt tabs. This puts the lead's just coming off of the driver's terminal stuck to those tabs.
..so, I pull-out the "crazy" glue (Cyanoacrylate), use gloves (disposable), glue the leads and press them firmly on the felt tabs for almost a minute.
-and the interesting thing was: it didn't hold.. at all. (..stuck wonderfully to the gloves though).
I don't think I've ever had that type of glue NOT work before, but something about the VC (flux?) - just wouldn't work with that type of glue.
The fix was easy of course: hot glue gun. 😀
-burnt my finger a little though (..4 times - it was 2 drivers). 😱
Turns-out it was the cone hitting the VC leads which were sloppy-large: plenty of VC lead, but the natural bend down to the VC sagged to low: on recovery the cone slams into that "sag" from the VC lead.
Fortunately there is enough lead there to sort of "lift and separate" (like a bra on an old woman
) and still allow for more than enough excursion (even when pushing well beyond the gap).My solution then was to put some felt tabs on the frame (inside/underside) near the driver's terminals and "lift/separate" them to those felt tabs. This puts the lead's just coming off of the driver's terminal stuck to those tabs.
..so, I pull-out the "crazy" glue (Cyanoacrylate), use gloves (disposable), glue the leads and press them firmly on the felt tabs for almost a minute.
-and the interesting thing was: it didn't hold.. at all. (..stuck wonderfully to the gloves though).
I don't think I've ever had that type of glue NOT work before, but something about the VC (flux?) - just wouldn't work with that type of glue.
The fix was easy of course: hot glue gun. 😀
-burnt my finger a little though (..4 times - it was 2 drivers). 😱
Help wiring a 4P3T switch
- By pelayostyle
- Parts
- 6 Replies
I'm either having a massive brain fart or a stroke because I can't visualize the physical connections of a 4P3T switch as described in the excerpt below. Its driving me crazy, so I've come to you geniuses for help.
Can someone please create a simple wiring diagram in MS Pain, for example, of how this switch layout would be wired?
Thanks
Can someone please create a simple wiring diagram in MS Pain, for example, of how this switch layout would be wired?
Thanks
Ultra low noise PSU on e-bay
- By keilau
- Power Supplies
- 72 Replies
LT3045 LT3094 Positive and Negative Low Noise Regulated Linear Power Supply New | eBay
Any first hand experience or measurement with this PSU board? It uses the LT3045 and LT3094. If those were genuine IC, the noise performance should be very good. The small heatsink may need a 30-40mm cooling fan if more than 100 mA output is desired. The small board size is very attractive for low power, phono stage application.
Any first hand experience or measurement with this PSU board? It uses the LT3045 and LT3094. If those were genuine IC, the noise performance should be very good. The small heatsink may need a 30-40mm cooling fan if more than 100 mA output is desired. The small board size is very attractive for low power, phono stage application.
For sale: new unused ERSE Super Q 2.0 mH inductor pair
Up for sale is a pair of new unused ERSE Super Q 2.0 mH inductors. These are solid core devices wound with 16 AWG wire and have DCR of 0.143 ohms. Parts Express sells them for $22.48 each.
ERSE Super Q 2.0mH 16 AWG 500W Inductor Crossover Coil
The price is $32 for the pair + shipping and PayPal fees. I have 5 pairs available.
ERSE Super Q 2.0mH 16 AWG 500W Inductor Crossover Coil
The price is $32 for the pair + shipping and PayPal fees. I have 5 pairs available.
Attachments
Sinewave oscillators: 1. The gain control block
- By Elvee
- Equipment & Tools
- 17 Replies
I would like to launch a series of discussions about the design of low-distortion sinewave oscillators.
There are already a number of threads dedicated to the subject, this one being a typical example.
Together, these threads represent a huge amount of information(s), but they tend to be large, messy, and mix up new ideas, old designs, SOTA designs, and revolve about all aspects of such oscillators and sometimes unrelated subjects.
With thousands of posts, any relevant information tends to be drowned in an ocean of "noise".
Here, I will discuss each aspect in turn: gain control will be the first one, but I also intend to discuss topologies, active elements (gain blocks), amplitude acquisition and filtering, passives, etc.
I am not interested in the current state of the art: this can be found on the net, or here, without too much effort.
I would like to see new approaches, and they could be new takes on existing solutions, or completely new solutions.
I am going to illustrate that point, based on the classic jFET VCR example:
First is the classical implementation, with all its known issues.
This basic circuit can be improved by using a more clever summing scheme, to improve the accuracy and speed of response: SOTA.
Both the previous circuits suffer from a residual non-linearity and limited dynamic range.
It would be interesting to find a corrector network, to lower the distortion and improve the dynamic.
Only the last circuit would qualify, because it brings something new.
I am going to prime the discussion by presenting a gain control based on lambda/Early effect.
The Early effect, and its FET counterpart, the channel modulation are non-linear effects.
They are generally seen as a problem, because they increase the THD of amplifiers, but would it be possible to take advantage of them to create novel types of VCA's?
The answer is (apparently) yes. This drawing illustrates the principle:
The output resistance of the transistor can be modulated by the collector current or the Vce.
The dependence on the Vce is what causes the non-linearity in amplifiers, but Ic provides a convenient, direct means of controlling the resistance.
Of course, using a single transistor would be somewhat impractical.
A push-pull configuration seems ideal, since it neatly solves DC issues etc:
Now that there are two active elements, the Vce term disappears, meaning the synthetic resistor becomes linear (assuming the Early law is cast in bronze, which is not exactly the case unfortunately).
Things are not that simple though, mainly because complementary transistors are a fiction that doesn't hold in reality (in silicon at least).
Parameters differ widely, and Vaf (Early voltage) is heavily affected: PNP's have a much lower Vaf than NPN's.
The solution is to go all PNP:
This is a first, half-practical example. I will examine later its shortcomings, and possible remedies.
I will also introduce a figure of merit, to evaluate more objectively the various alternatives.
The simulation shows an amplitude sweep, from 6Vpp to ~0.6Vpp
There are already a number of threads dedicated to the subject, this one being a typical example.
Together, these threads represent a huge amount of information(s), but they tend to be large, messy, and mix up new ideas, old designs, SOTA designs, and revolve about all aspects of such oscillators and sometimes unrelated subjects.
With thousands of posts, any relevant information tends to be drowned in an ocean of "noise".
Here, I will discuss each aspect in turn: gain control will be the first one, but I also intend to discuss topologies, active elements (gain blocks), amplitude acquisition and filtering, passives, etc.
I am not interested in the current state of the art: this can be found on the net, or here, without too much effort.
I would like to see new approaches, and they could be new takes on existing solutions, or completely new solutions.
I am going to illustrate that point, based on the classic jFET VCR example:
First is the classical implementation, with all its known issues.
This basic circuit can be improved by using a more clever summing scheme, to improve the accuracy and speed of response: SOTA.
Both the previous circuits suffer from a residual non-linearity and limited dynamic range.
It would be interesting to find a corrector network, to lower the distortion and improve the dynamic.
Only the last circuit would qualify, because it brings something new.
I am going to prime the discussion by presenting a gain control based on lambda/Early effect.
The Early effect, and its FET counterpart, the channel modulation are non-linear effects.
They are generally seen as a problem, because they increase the THD of amplifiers, but would it be possible to take advantage of them to create novel types of VCA's?
The answer is (apparently) yes. This drawing illustrates the principle:
The output resistance of the transistor can be modulated by the collector current or the Vce.
The dependence on the Vce is what causes the non-linearity in amplifiers, but Ic provides a convenient, direct means of controlling the resistance.
Of course, using a single transistor would be somewhat impractical.
A push-pull configuration seems ideal, since it neatly solves DC issues etc:
Now that there are two active elements, the Vce term disappears, meaning the synthetic resistor becomes linear (assuming the Early law is cast in bronze, which is not exactly the case unfortunately).
Things are not that simple though, mainly because complementary transistors are a fiction that doesn't hold in reality (in silicon at least).
Parameters differ widely, and Vaf (Early voltage) is heavily affected: PNP's have a much lower Vaf than NPN's.
The solution is to go all PNP:
This is a first, half-practical example. I will examine later its shortcomings, and possible remedies.
I will also introduce a figure of merit, to evaluate more objectively the various alternatives.
The simulation shows an amplitude sweep, from 6Vpp to ~0.6Vpp
