This is a set of boards/parts you need to assemble M2. I was using this amp for quite some time as it sounds quite nicely and can drive various speakers without issues. It comes with caps and PSU boards that you will need to populate (actually, I can do it for you if you would like). Only things are missing for the amp to work: 18VAC transformer, 1R resistors for CRC in the PSU and a chassis. A couple of things: the PSU board is not from the store, it is some ebay board I got from a friend, but I have built with a couple these and they work fine. There was a small layout mistake one of the boards, so there some good old p-t-p soldering present. No difference other then cosmetic, I'd say. Price is $270 shipped in US. Thank you for looking.

I have this one I got from a fellow forum member sometime ago, but never fire it up. It just needs to solder LEDs (included) and connected to the transformer, included as well. Oh forgot to mention: it has 12(!!!) almost unobtainable original Toshiba k170 jfets! This one was designed back when people enjoyed their life and creativity 🙂. Price is $170 shipped in US. Thank you for checking!

Hello everyone, I was wondering if there is any way to fold a tapped horn that I have designed in Hornresp around the "BEYMA 15MC700Nd" driver without spending my whole life trying to do it 🙂. I'm familiar with Brian Steele's Excel sheets, but when I try to import the data from Hornresp using the "IMPORT SIM" button in the folding type "SS" excel, and then click the "OPTIMIZE" button, the sheet gives me an incorrect model, attached images below.
By the way, I know the mouth is 8920cm2, but even when I try it with another model like the "v2," image attached below, it still gives me a model with a weird shape or modifies "s1," "s3," and "s4," causing it to no longer have the same frequency response. I was wondering if I'm doing something wrong or if there is another way to fold my Tapped Horn. By the way, the final dimensions of the folded box don't matter to me; it can be any size. Any response will be greatly appreciated, thank you!!

Selling a pair of Audio Note AN-K I/V transformers.
Price 250$/pair. Dont know if that is a fair price?
Anyway, shipment from Norway. They have not been used for many years. Sourced directly from ANK

BR

I’ve been attempting to voicing my commercial speakers; ADS L1590/2, by eliminating some excessive mid-bass. The crossover between the dual 10” woofers and a 2” dome midrange is published at 350Hz with second-order slope for both high and low pass. What I have performed was lowering the woofers crossover frequency. Yes, it introduced more gap between two drivers. Yet, it’s fruitless, the problem still remains. Still, no space between midrange and bass was heard, but a little clearer midrange which is favorable and acceptable.

By the way, the original low-pass filter for the woofers is compose of a 3.5mH coil and a 100uF cap. I altered it to a 4.2mH coil and a 150uF cap. The high-pass filter for the midrange was left untouched consisting of a 2.6mH and a 33uF. Please forgive me for didn’t take a measurement because the speaker is about 42kg heavy. Nevertheless, trust my ear there’s a problem at mid-bass region, an Umm sound along with male’s voice and some upper bass boom.

I’m unsure whether that mid-bass comes from “upper frequency of the woofer” or the “cabinet talk”. However, as described above, I’ve done something to the woofer.

Consequently, I’d like to request for advices. What should I do next, without measurements? As far as I can think:

A) continue lowering the crossover point of the woofers’ low-pass filter
B) modify the cabinets, my friend suggested me to install the damping material for car’s doors to the cabinet walls.

Hi!
I googled a bit, but can't seem to find a solid answer. How to check for oscillations in a solid state discrete design? So far I got this:

• Overheating components can indicate oscillation
• Using oscilloscope to look for oscillations probing the circuit (sadly my only scope is ADALM2000...)
• Increased distortion (beyond expected values) when measuring the circuit

Happy to hear your point of view!

Circuit in question:


Schematic:

This is what is said a " standard Teac servo board " Do you know in which Teac / Esoteric model it was used ?

Hello Everyone,
Hope you have (Had) a Great Holiday.

Need some help with a Fender Rumble 25 Bass Amp that the Speaker Rattles like crazy when the volume go's over about halfway.
I tried another speaker and the same happens. I checked it out with a different bass and the same thing happens. I can also hear it through the headphones. So I figured maybe the power amp was faulty so I changed it (LM3876T) However the same problem. So I changed all the IC's (TL072CP and CA3080E)
No change. So I changed the three transistors that are in this model (MPSA63 and two 2N4401) still the same problem.
Any ideas??
Thanks, John.

Please I am looking for a scrap Technics SU-V6 we're I can canibalize the control unite controlling the Auxilary, Tuner phono and Tape mine is bad and I need it replaced. Please anybody having this should contact me on WhatsApp +2348166685002

I just got this minimal amp for backup of the DTA-1 from Parts Express I got years ago for desktop PC use. The AK-170 does not come with a power supply wall wart. No link for this as it was taken down... (see note on LED strips below)

I've checked for what was in the throw away box at the thrift store and they have lots of warts but usuable ones at 12 volt 3 amp as listed on the AK-170 seem to be rare. What stops me from just getting what are listed for a 12V 3A wart is "switching power supply." Some say this, some don't. And the strange thing is every time I look up one of these warts, the source is always (mostly) for LED power strips.
I don't want to waste any new errors on this thing. I've previously got a few tips on what to look for.

Eventually I'd like to get a Fosi as replacement. Parts Express just told me in a mail from their customer service that they are not bringing back the DTA-1. OTOH I saw a Fosi unboxing last night on Youtube and seemed to indicate that the Fosi doesn't come with PS either.

Hello!
First posting here, try to learn.
I have a Mission Cyrus Amp here. Later Model i think, no jumpers for PSX-R mode.
The Issue:
Amp switches on, plays the LED Sequence, all Buttons working inkl wheel are working but... no Sound.
Only a small „plop“ wenn turning the volume knob one "led-step". „plop“ too @ mute button. Mute button tested, fine.
Somebody know these issue?

Thanks for help!

AS the title says, a Sanwu HF-41 Amp + Bluetooth Board , and it has a HORRIBLE hissing noise (more noticeable at low volumes) when using the bluetooth input (but not when using the other inputs such as the usb input).

I see a million solutions for when the BT board and amp are separate boards, but I am looking for a solution to resolve this in my all-in-one board. I have not found an actionable solution that I understand yet.

Does anyone have any practical suggestions that a non-electrical engineer can understand and implement?

I am relatively new to this stuff (though I can solder, e.g. I've successfully swapped bad capacitors on TVs , etc.).

I have SO Many hours into this build, nearing the end, and this hissing noise during bluetooth usage is basically making it a junker. I'm so discouraged at this point, I don't know what to do.'

Happy to provide any other info, photos, etc. as needed (just not sure what other details will be helpful).

Hi
Attached are the output signals of two channels. One channel side, bottom wave clips and other channel top wave clips. Amp goes into protection. I removed the protection to get the waveforms.
All the rail voltages positive and negative are similar in value and low voltages are also good.

This module is easily availabe to me. Its passive tone control with volume, Bass and treble. Wanted to ask. What would be easy way to know flat (Original signal with no equalization to bass and treble frequency) response position of the controls ?

Thanks

Hi all,

I have a 2.5 way on the bench with the task to renew the drivers and xover, reuse is only the enclosure.
Still a little craftsmanship to do, but I'm thinking how to generate the measurement data for VituixCAD xover simulation best.

I plan to acquire following measurement data:

• 0° and 10° step hor/ver spinorama FR of every driver separately within the enclosure, at least half space +/-90°. Ideally, I can measure outside with >2m mic height in 1,5-2m distance on a little turntable.
• Near-field data of both woofers and the port to merge below 200-300 Hz after gating the spin data.

Challenge is how to handle the two midwoofers acting to one enclosure and resonator, but driven via two seperately filtered electrical pathes.

I think the nearfield data and merge is easiest:

1) Connect both woofers in parallel to the measurement amp. Run the sweeps.
2) Measure port nearfield response, and nearfield response randomly* of one of both woofers.
3) Prepare diffraction response of both woofer positions in Vituixcad baffle simulator.
4) In Vituixcad merge tool:
- load random woofer nearfield response and scale to 1x woofer cone area
- load port nearfield response and scale to 1x port area, and then substract -6dB
- load specific woofer diffraction response
- load specific woofer gated anechoic response --> merge and export
- repeat with second woofer

*) Rationale: Both woofers shall act same in the nearfield at these low frequencies and driven in parallel. I would nevertheless measure both, but more for integration check that the cones are healthy and no standing wave resonance within the enclosure introduces disturbance - so to verify that they act same.


Spin data gets more interesting.

a) Option "lazy":

• Connect both woofers in parallel, go to somehow ~2m measurement distance, and do only 1 spin for the woofer path
• Substract -6dB from the responses, and just use the same for both channel xover path simulations.

For the horizontal data it might get not that wrong, but how will that affect overall vertical system response simulation, especially in the range they are filtered differently it would be messed or? Or I am even "super-lazy" and only take horizontals for the filter tuneset in simulation...


b) Option "Cover":

• Build a tight and stiff cover, that fits exactly one rebate hole for the woofer
• Close/plug the port.
• Mount one woofer, and close the rebate for the other with the cover. Do the spin.
• Exchange woofer and cover. Do another spin for the second woofer data.

One woofer will not interact with the port as two will do, so better close it as the measurements were anyway gated below 200-300Hz.

Sounds like a solid solution?
The cover may have a bit other shape than a woofer cone, so there might be some difference in baffle reflections between the measured and later used system.
And I'm too lazy to build that cover ;-)


c) Option "electrical damping":

• Close/plug the port.
• Mount both woofers to the enclosure. Connect one to the measurement amp, and shotcut the clamps of the other. Do the spin.
• Exchange amp connection and shortcut. Do another spin with the second woofer.

Could work, or?
Ideally, the short-circuited driver will see somehow similar conditions like in full speaker operation (there with zero ohm drive impedance from the voltage amplifier at the clamps)?
--> Have to do some math and thinking, anyone concepts/equations/models for input?

Anyhow, could be a solution for the gated measurements above 200-300Hz, with the resonance frequency behavior changes between the different "pneumatic" operating conditions well damped and below that range.
Will try that out first in comparison to both drivers connected parallel (and with one open clamp driver also for interest) before building a cover....


Do you have experience, hints or thoughts about measurement data acquisition from some 2.5 way?

Thanks a lot and best regards
Peter

I need just 3 metres or so of film and it only needs to be 200mm wide, so maybe someone has some offcuts of a suitable size ?

I'd like to share my experience with this. So far, I have converted one pair of Magnepan 3.7, two pairs of 3.6 and one pair of 1.6 to active crossovers. Well, I also did a pair of 1.5, but that was later reverted to the original passive crossover.

The first question may be - why do it? First of all - because you can, and it fun and easy to do. You can also make it a much better speaker in my opinion.

The first task will be to open the speaker and bypass the internal crossover. All Magnepans made the last 30 years or so have an internal crossover located below the speaker panels, facing the front side of the speaker. Some, like the 3.6/R, also have an external in addition. I guess they did it like that because they couldn't fit the whole thing inside the speaker. The later 3.7 have a rather odd series crossover, which requires less parts. The entire 3.7 crossover resides inside the speaker. All 1.x, 0.x models, the LRS, 20.7 and a few others have internal crossovers only.

There are basically two ways of accessing the crossover:
1) Take off the "sock" or cloth cover
2) Cut a hole in the cloth

The latter can be done with 3.6 and 3.7, as the front cover can be taken off, and the hole in the "sock" will not be visible. On any 1.x model, you need to take off the "socks". The next post will cover how to open a 3.6/3.7.

New Old Stock. For use with A series amps and Ariston AX series. $29?

This isn't audio related but the principals should still apply.
The application is a lighting coil on an engine which uses a single diode, half wave rectifier, with a shunt regulator to produce pulsating DC for the lights. I would like to switch to LED lighting but with LEDs the flicker at lower rpms is very pronounced so I was thinking of modifying it to use a high speed bridge rectifier. What I'm wondering is how that would affect the load on the lighting coil? I don't want it to overheat and burnout.

Hello all. I am in the process of refurbishing two pairs of klh model nines and could use some parts. Does anyone have tweeters and or power supplies for sale? Also, if anyone repairs these power supplies in the Massachusetts area that could work also. Any guidance on this journey would be great.

Tube amplifier sockets
18 new in packaging chassis mount.
28$ + shipping

I’m rebuilding a pair of Carver ALS Plats. Replacing all the 12” woofers and upgrading to 60” ribbons. Removing the internal crossovers in favor of using a miniDSP flex8 for external crossover and driven by two Carver M500t amps. What value cap is needed to block DC to the ribbons?

I bought some Twisted Pear Audio modules (kind of a random seeming assortment) from an estate sale a while back and I would finally like to do something with them. Here is what I have:

Buffalo 32S
COD
2x Ventus EZ
Opus USB receiver
2x Opus WM8804 Receiver
LCDPS
2x LCBPS

I was planning to use these widgets to deliver I2S to the DACs instead of the receiver boards, since I am mostly coming from tube/vinyl land and my only digital source is Tidal via smart phone.
So my main question is about the PSU modules. I was not able to find any info on the Twisted Pear website about them. Can anyone help me understand what transformer to will power them, and what voltages they put out?
I also clearly have two DACs and one I/v stage... is the Ventus better suited to one of the DACs and not the other? Or might I just as well tryout both DACs with the Ventus, if i get it all up and running?... I will be using everything single ended.

Any help (especially regarding the LCDPS and LCBPS) appreciated,

Hello -
Not sure if I should be posting in a specific thread, so if this is not the right thread please let me know!
I have 2 Black Gate dual-section capacitors that are 220uF / 350V, and each can has a common ground. I think it seems obvious, but is there any way of connecting them to get a higher voltage without losing a section in each? I need about 480V on the supply. I was planning on using them in a CLC filter, but now seems that's out the window with the common ground.

Thanks!

Just purchased a large quantity of a CG Electronics
75 Uf 600V 5% Metalized Polypropylene Capacitors
They Measure 3 1/8" long X 1" thick and have 3/4" leads
Price $3.95 each

818 248-0416
steve.apexjr@prodigy.net

Is there a place for a dedicated thread on Micro Controllers In Tube Amplifiers? If there is no interest the thread will die.

I was reading the thread by jcalvarez on Hybrib Bias For Output Stage, and a comment by Chris about servo bias made me think of using a micro controller.
I have been tempted to use a PIC micro as a set fixed-bias device as it could also function as a fault detector possibly operating a SCR crowbar fuse type emergency shutdown on the on the B+. One micro could monitor all the tubes in the amplifier, better to blow a fuse and flag an error rather than damage expensive components.
I'm certain many forum users are very skilled in the use of micros and programming.
Maybe some readily available boards like the Arduino range could be employed and be powered from the heater supply, code and designs could be shared.
Rather than over complicate the amplifier it may be possible to protect some expensive hardware relatively cheaply.
Some possibilities:
shorted tube detection
arc detection
set bias
flag weak out of spec tubes
auto shut down after inactivity
emergency SCR shutdown
detect shorted/overloaded/open circuit output
clipping indication maybe a LED
B+ delay (relay)
soft start B+
RF detection
low/high voltage mains detection
faults could be flagged and saved to eeprom, fault codes could be cleared by pushing a button.

For a simple device no programming approach trim pots could set bias and other parameters.
Maybe someone could write a phone app.
If Arduino was used the program parameters can be edited using free software. Arduino use C++ I think.
As far as possible the designs could be fail to safe.

ESP32's seem to be fashionable at the moment, I believe one can use the Arduino IDE.
Some PIC's have stood the test of time and seem to be very good, a custom board would need to be made. There is free software about for programming PIC's (C and BASIC).
Custom PCB's would be the best approach. The board could be relatively simple to install and should not impact the sound quality apart from precise the auto bias as the tubes age. Bias information would be held in eeprom.

Hello people, I need information on how many watts these resistors have to withstand, blue: 39 ohms, yellow: 100 k ohms and red: 22 ohms, thanks in advance

Hi all, just listening to some lp's when i came across this picture lp. I thing its a promotional thing as it does not sound as good as real lp.
What are they made of? Is it pvc?

Dear friends.
I build this vintage quasi amplifier in ltspice. I just start using ltspice a few days ago so i wanted to know that how to simulate it. Need advice and tips.
Thanks in advance.

https://www.parts-express.com/GRS-PT6816-8-8-Planar-Slim-Tweeter-8-Ohm-272-128?quantity=1

I had these on order for a short array project but they were on backorder for months so I cancelled…..notw they’re back in stock but I put that project on hold. My plan was an open baffle array from 800hz on up. Just wondering how they sound overall. The array would be 8 elements so I don’t think the 800hz crossover point would be an issue

This Transformer has a 117v Primary and was removed from a Brand New Amplifier . Has some rust . New old stock. See picture for secondary winding data. Great for that Hybrid Amplifier project.

$45 Plus shipping

Hello,

I want to build a spherical speaker, but I don't really know how to do it.

What exactly do I have to consider when designing the housing and which calculations do I have to make?

How to calculate the size of the case for a normal box is written a thousand times on the internet, but how do I do that for a spherical case?

can someone give me something like a guideline?

Selling a new Sony VFet chassis I got from the last group buy. Package has only been opened for inspection.
I can add a pair of vfets 2SJ28. They pass the diode test and the complementary ones from the same batch were fine.



I hope to get back what I paid for them.
The chassis can't be ordered anymore. £250
The Vfets are £100 extra
Shipping from UK

Hey there,
So I have this Ibanez bass and for the last few years the active function has not worked. Passive is fine, but when I switch it over to active there is literally no sound (not even a hum). Naturally, I’ve tried several batteries, but the issue persists. I’ve started joking that’s it’s my bass’s kill switch; however as time has gone on I’ve wanted to get my active back. On the inside, no wires connections to the active switch seem to be amiss. There is one wire that runs from the pickups to the bass knob (see second photo) that is not insulated, but I’m not sure if that could affect the active system. I will attach photos to see if any of you can see something I’ve missed.

Hello to all,

I just received a used Meridian 506.20 which arrived slightly defective from France: It would not play any CD. It sometimes manages to recognise CDs (display total duration of CD and number of tracks), which indicates laser mechanism ok, but not play them - neither error codes nor a 'No Disc' message on the display though, display shows 4 horizontal lines when inserting disc.

After a bit looking closer I noticed that the black CD holder cap from the drive spindle had been fallen off (I still have it but it's detached from spindle). If I carefully place it again on its originally position, the CD player can play CDs again - beautifully so.



How do I properly align it on its axis and mount it again - super-strong glue?

Best and thanks a lot (alone the smooth tray slider mechanism of the Meridian is a sight to behold, so much like to make this thing running again!),
mbosse99

Hi DIY'ers.
I have recently bought a FM300A clone from Aliexpress.
I would really like to have the diagram or a service manual for the amp, does anyone know of this?
I have found the diagram for the amplifier section alone, but would like to have the power supply and auxillary circuits (relay control, peak detection etc) diagrams as well.

Does anyone have it, or know of a place/shop that does?

Kind regards,
The Priest

Hello everyone,
First, Im sorry if I didnt choose correct place/options to start this topic.
So I rly need help, and I dont know who else to ask. I have almost new bluetooth speaker - medion P61468 (MD44468) - used maybe 5 times and it died. It shows that it charge and it shows when battery is full (red and green led) but I have no display and I cant use any function to play sound. So I try searching for parts, mainboard, I look for broken speakers as well, I cant find anything. So I unscrew it check power supply and battery and its good, I check power swich, also good. So I guess main board is causing issue.
So you probably wonder what help do I need, any tip on what to look on mainboard, what to test and try replacing it would be helpful.

OR tips with this:

I have speakers, power supply and almost new battery, I was thinking why not use it for parts and build my own speaker, I know its possible just Im not rly good with choosing parts because lots of things I dont understand (compatibility things).
So I have 2 x 3ohm-40w speakers, and 2 x small one (I know name of those on my own language but on english idk how you call those), so I need some bt audio controller for those and Im not sure do I need battery controller or it has one inside separated from main board ( they glue it so much that I gave up from looking inside battery case for now). Im also not sure can I use power supply from the speaker (12v).If anyone have some tips, guides, videos that I can watch that would be helpful or links with parts that I need and that are compatible with these speakers and voltage that I have... that would also be great
So please guide me if you know what can I do with this medion garbage that I have and dont buy medion speakers, I still have warrenty but its cheaper for me to buy new one than drive to store where I bought this and dont trust their pictures, they have 2 cosmetic speakers made of plastic with 0 wires inside.

I'm looking for driver recommendations for my latest speaker build; a super high quality nearfield 'monitor' set for the study. I'd also value opinions on weather going 3-way is warranted in a small high quality build with max 5" woofer.

Project requirements:

• These will be for nearfield use, about 1m away from my face.
• The cabinets will be 10L, sealed. I have something special in mind... 😛
• I want super high quality midrange
• I want as much bass as i can reasonably get. I will likely EQ digitally or in analog, or even use room correction to extend out what i can get out of the relatively small enclosures
• I'm not looking to play at very high volumes so it can be vastly inefficient if it needs to be
• I'm undecided if i should go 2 or 3 way. I struggled with my last attempt at a 2-way with an 8" woofer, it never wanted to meet the tweeter properly and mids suffered. With a 10L cabinet and the right midbass I am wondering if a 2 way might be acceptable...

I generally like the sound of rigid cones and am keen to experiment with some of the more open backed drivers. So far i have found the Seas W15CH001 which looks promising. Scanspeak also do an intriguing looking 12MU/8731T00, but it appears not to be suited to a 10l sealed box at all. Are there any others i should consider?

Thanks!

Searching for one for testing... Can be unpopulated or populated....

Hi all.

For sale Sigma 22 set to +-15 volt. Aks 40€ plus shipping.

Open to offers.

Regards

Preamble: I'm doing some work renovating a 1980s-vintage, very lovely solid state, discrete component Meridian MCA pre-amp. They originally shipped with a crappy little single input and output IE transformer that rattled about in a plastic box external to the pre-amp itself. It put out an AC voltage through a twin-core umbilical into an unscreened socket marked with a notional 19V AC requirement. I have one of the 2 original transformers (the other is for another piece from the same stable - the MFM Radio module) which doesn't specify the VA value: there is just a faded label marked '225-115-0'. The only other thing that may or may not help is '35 x 3/4S' (3 over 4) engraved on the plastic back cover. A quick, gash, test on my home supply (nearer 240V than 230) gave me an unloaded secondary output of 22V - 3V more than the notional loaded figure.

There is a lot of discussion about suitable VA values for Power Amplifier transformers, including talk about extra headroom etc, but very little guidance about pre-amplifiers, which draw significantly fewer Amps in their normal use. Nor whether there is a need for headroom above and beyond the notional maxima of - say - linear regulator chips. The MCA pre-amp PSU has 78/79XX TO-220-3 regulators on its main rails, stepping down to +/- 15v via TO-92-3 devices further downstream so my instinct was to go for something that could go up to the full 1A capacity of the TO-220 components. But would this be overkill?

Question(s): Is there a need for a higher current-handling figure than that suggested by the schematic, when this may result in the transformer not being fully loaded to its nominal output? Is there a 'typical' total amperage figure/range for a domestic preamp that I could safely use? Instinctively I think we're talking tens of milliamps here. I'd value some guidance about whether there's a rule of thumb along the lines of 'known amperage x 1.25' or something... and, as I'll still be using a transformer in a separate housing outside the component case, are there any considerations about the best type to use, about screening the umbilical, filter components integrated with it, etc. Assuming that Meridian would have not gone overboard with the original spec, can I deduce the VA value of the original transformer from its loaded v unloaded voltages, and use that purchasing a new one?

WTB Kevin Gilmore CFA3 boards.

Hi all!

I'm quite new to electronics. Since I've been a child I've been fascinated by it but didn't got a chance to learn a lot about it. I've learn some basic of programming and thought myself a lot about computers in general. Now with the age of internet and microcontrollers this all has become much more accessible so I've started this hobby to do thigs I'm interested in.

Recently I began working on a project with ESP32 to implement my speakers which a are of good/ok quality to be used in the living room for out TV, listening to music from a phone over Bluetooth and adding internet radio, and maybe even FM radio if it'll be necessary. It's quite an extensive project and since I've always research stuff before I go into them I've noticed that I often ended up here on this forum, thus I've decided to join it. To contribute and share my experience.

SMD B1K Nutube, brought to perfection, quality of sound follows. This is my second custom iteration of papa Nelson circuit, this time on a very small footprint (board size is 6.5x6.5cm, case size is 15.8x9.2x4.7cm) using best available parts. Jfet buffers are jfe2140, signal capacitors are amazing rubycon mu 4.7uf 35v, filter caps are 1800uf 25v UHW nichicon, vishay dale 5W 270R resistor, metal element 10R 2W resistors, rest of resistors are 0.1% thin film. Nutube is decoupled by custom board and specifically chosen sponges with silicone polimer binder in between. Rubber standoffs to decouple entire board from case, wire to nut gnd. P089ZB custom filter is applied as well, amazing pairing to this little beast (there is enough room for another one if you want to daisy chain). Wiring is upocc copper neotech for signals. Alps potentiometer included, with enough room if you want to put something more niche instead. In the package is included power brick from original nelson kit (you may want to up the game there with meanwell rs-25-24 for aditional few % performance). Everything together amounts to very significant performance upgrade, from smaller signal path, top of the line smd jfets, best smd film caps, large filter caps, to board design..

Selling this so i can finance the same project, but as buffer boards for my purifi 1et400a amp, somewhat like atm audio.

Price is 250€ + shipping

I scored a Conar 221 in good shape today. Seems to work just fine and came with all the original paperwork and a few extra documents as well. I have a Stereo 70 I am
Retubing, this will be nice to have on hand. I used one often in the mid 90s when I was building a lot more vacuum amplifiers. I’m glad to have this at my disposal again…

This thread is intended to be dedicated to 3D print designs that can be used with various Modushop HiFi2000 chassis. The intent here is to create a single location where people can share all sorts of 3D CAD designs that can be printed on a hobby 3D printer which interface in some way to a chassis, particularly those which are provided by Modushop. I will start this thread off with one simple design and we shall see where it goes. This is my first every thread I've created, so any advice to maximize it's value is greatly appreciated.

I'll edit this first post and put the latest versions (assuming there is a revision) here to help keep everything you may want to download in a single location.

Here's a link to a vertical mount for both 300VA and 400VA Antek (or other similar sized) transformers. Total cost for this is under $5 if you can get access to the 3D print file. Reach out to me via PM if you need a print made and you're willing to pay for shipping.
https://www.diyaudio.com/community/...ing-of-antek-300-400va-3d-print-files.410476/

Here's a link to a horizontal mount for both 300VA and 400VA transformers that lifts the transformer up enough to fit over a lip up orientation on a Modushop 4U/300 chassis. It just moves the transformer a little closer to the front plate when using the lip up orientation of the perforated plate.
https://www.diyaudio.com/community/...on-over-chassis-plate-lip-up-3d-print.410708/

Hi All,

A bit of a long shot, but if anyone has one or two of the older JA 8008 mid woofers I would be interested in buying these.
Thanks,
Nic

Hi

I have a number or sources with I2S out. I would like to use a DAC with balanced line out or easily modded to add rather than a seperate add on board.

Ideally a budget solution (<$50) there use to be a bunch of offerings on AE.

Suggestions?

I'm planning to have a sub box made to put in the rear footwell behind the drivers' seat. And I'm currently enamored with the idea of twin 8" opposed for force canceling. At external dimensions of about 9x12x20" that means let us say 0.84 cubic feet, which would be 0.42 cubic feet per woofer, ignoring any stuffing effects for now.

Here are three quite different woofers to consider:
https://rockfordfosgate.com/products/details/p2d4-8/ which I can get FREE!*
https://www.parts-express.com/Dayto...-Series-HO-Subwoofer-8-ohm-295-459?quantity=1
and the seemingly unsuitable
https://www.parts-express.com/LaVoce-WAF082.00-8-Woofer-8-Ohm-293-714?quantity=1

Can someone kindly simulate these with actual SPL?* Just a simple model, never mind inductance and all that, and never mind Xmax. Please feel free to comment about those things! But my interest here is what happens just like below 80 Hz, I am curious. Suggestions about a single 10" or 12" also welcome as alternatives to the twin 8"

Domo arigato!

*(I plan to install WinISD but have some problems with that since the machine is at work and I need IT Department to install it. But if the Rockford is good enough I can ask for that later this week 😀
If I simulate at https://speakerboxlite.com/subwoofer-box-calculator/tab-graphs the curves all look the same at the low end since they are all below resonance. The LaVoce looks "lower" but this simulator does not do actual absolute SPL, and if I offset the zero level it seems maybe it would be almost the same at very low frequencies.)



BONUS questions:
3/4" material? Or 1/2" material to gain a bit more internal air space? Or give up a bit more for super solid 1" material? Presume internal bracing and anti vibration goop (what goop though? I'm out of touch with this)/

Something around 16 Mhz cheap and good 🙂

Hi guys!
I have problem with output transformer on SE TH100 monoblock amp. Transformer is James Audio.
Sometimes it starts buzing,long,short,quiet,loud...there is no rule to the patern. But now i find out that buzing get much quieter when i put my hand on transformer.
Any idea what is problem?
Everything is nicly connectet,ther is no poor conection insida amp. I give it to some guy who "fix it",he change so resistors on power transformer,but problem stay.
I have DALLAS II speakers with fostex 206s so they are very sensitive,so buz its too too loud forbmuzic listening.
I try to put new tubes,change tubes from one monoblock to another,but nothing changing the ptoblem. Second monoblock work with no problem,perfectly.
So,any idea?

I've been adjusting the tonal balance of my 3-way speakers. Previously, they were tuned to be flat. But now, I've decided to add some Bass EQ to them.

Bass EQ is simply the attenuation of the mid and high. I added L-Pads to the mid and high and tweaked them slightly until the new amplitude curve was perfectly lean on the original. However, for the bass section, the original crossover is implemented using a second-order configuration with L = 3.5mH and C = 100uF.

Since I don't have any experiences about equalization, I'm hesitant to choose the mid-to-bass or Bass EQ curve.

Attached are the plots of new versus original curves for comparisons. There are five different shapes of bass EQs made from parts (inductors and capacitors) I have. I've tried listening to all of them, but I still can't decide.

A ) 3.5mH and 100uF (Original combination)
B ) 4.0mH and 130uF
C ) 4.2mH and 150uF
D ) 5.0mH and 70.5uF
E ) 5.0mH and 100uF

Please advise which option is the most appropriate.

I ask in all sincerity: If something like a Firstwatt amp can be built with such high sound quality and so few parts, why are most commercial offerings from all eras so complex in parts count? I understand manufacturing (my profession) and that in the end viable commercial solutions come down to dollars and cents along with being reliable and stupid proof (that alone takes time, energy and resources! A LOT of money goes into stupid proof!). In general, the more parts the higher the cost in both acquiring those parts and labor to install them; unless those more numerous parts are so insanely cheap they can do the job of fewer more expensive parts. Or perhaps those numerous parts make the product more universal to all markets so money is saved by having a single highly numerous product as opposed to variants in a smaller number. Or perhaps something else altogether?

When you pull the covers off most audio components, especially anything that is not "esoteric", you're staring at MANY devices whether they be passive or microchips. That said, what am I overlooking?

I bought a Pioneer PL-516 for cheap recently with the intention of rebuilding and flipping it. As purchased the belt was gone but the motor ran when the tonearm was forcibly moved; it was mechanically bound somehow inside the plinth. A Grado F3+ cartridge was present on the tonearm which I took as a sign that at one time this turntable was cared for. Upon teardown I found that the automatic mechanism on the bottom of the tonearm had jumped track and thus bound up. With the adjustment specs from the service manual in hand I disassembled the automatic mechanism and got everything realigned correctly and moving freely. A new belt was installed along with replacing the caps on the motor control board (kit available on ebay). The PL-516 motor control board provides separate fine adjustments for both 33 and 45 rpm and with the coarse speed adjustment on the tonearm base set in the middle both fine adjustments were able to be dialed in. Standard cleaning and lubing of all switches and pots along with the motor board cap replacement and new belt had speed holding rock solid. The turntable appeared to be in good condition other than whatever heavy handedness had caused the tonearm automatic mechanism to be askew and I found nothing broken or finicky; the parts are pretty hardy.

The PL-516 has a heavy particle board plinth covered in vinyl. The power transformer and motor are both mounted to a small steel sub-chassis bolted to the steel bottom plate and isolated from the chassis with rubber bumpers; a nice touch. The cast metal tonearm plate assembly bolts onto the top of the plinth and can be easily removed as a whole after unplugging a few connectors and switches without having to touch the tonearm wires themselves. Once I had all running correctly I swapped it into my system and realized immediately I preferred this combo to the Technics SL-B2/Shure M97 combo I had previously used. So much for the plan to flip the Pioneer!

Once I decided to keep the turntable I stripped it back down to veneer the plinth. The vinyl stripped easily with the help of a heat gun and then a scraper stripped the remaining glue. A quick hit all over with 80 grit on a palm sander to clean and square the corners and the plinth was ready for veneer. I prefer to use paper backed veneer and contact cement and had enough scraps of zebrawood on hand for this project. Veneering is straight forward but covers all the screw hole locations for the hardware to bolt back on. Often times these can be marked onto paper and located once again after veneering but in this case I used a tiny pin vise twist drill to drill pilot holes from the top and completely through the bottom of the plinth. This way once the veneer was applied I could drill upwards with the same tiny drill to make a hole in the veneer to locate the screws.


Platter removed along with steel top plate. The entire tonearm assembly is held in by the four remaining screws and can be removed as well after unplugging and/or removing the switches, neon and tonearm wires. Motor sub chassis is at top left with transformer hiding underneath. All four corners of this sub-chassis rest on large rubber bumpers to isolate vibration. Motor control board is just below motor and mounts inverted. The two small holes on left side of motor board allow independent adjustment of 33 and 45 rpm speeds. There are also holes in bottom plate to allow access to these adjustments.


Plinth veneered, stained and with two thin coats of water based poly. I didn't have a veneer scrap large enough to cover the entire top so had to use two pieces, but the grain of the zebrawood makes the seam invisible. New RCA cables were wired into the tonearm connector and out the back at the stock location. These are quite thicker than the originals so care must be taken to ensure they don't disrupt operation of the automatic mechanism.


Overall view in place. Dust cover needs to be sanded and polished. I thought of painting the tonearm base satin black but now feel I prefer the factory almost champagne color.


Closeup of plinth.

This turntable drives a Pearl 2 phono preamp and though I had no complaints of the Technics SL-B2/Shure M97 previously in place, the Pioneer PL-516/Grado F3+ combo is the clear winner to me. The Pioneer does everything better and is far quieter. I experimented with swapping cartridges between the turntables and in my opinion the Technics sounded best with the Shure cartridge and the Pioneer best with the Grado cartridge. Not a bad find for a broken PL-516!

Brand New, never used.
Has been tested

Specs:

Primary dual 120v 50/60 Hz
Secondary 360v C.T. 250ma
6.3v, 3a

$65 plus shipping and any PayPal fees

Looking to build first 2 way and want it to be above average but not really SOA. Willing to spend about 500-600 on drivers. My neighbor is cabinet maker but only looking for basic box. Would also like to entertain an 8" driver maybe 7" if better to extend down some. Will be used in large space also more than likely an active design using active crossover at least to start with. Really would like to try out something highly regarded in tweeter more like ring radiator or the like. I think that is enough to start. Let the feedback begin.

Dear DIY Audio Community,

In this thread I like to discuss a amplifier / speaker protection circuit that I designed.


Foreword:

I once fried a speaker by turning equipment on the wrong order.
As a countermeasure I improvised a circuit to delay speaker connection on power on.
So far so bad.
I like to get rid of the improvised delay circuit and have a real protection circuit instead.
There are a lot of modules available on the market, some even extremely cheap to buy.
I also found lots of circuits.
But none work the way I need them to.


My requirements for a speaker protection circuit:

1. Delayed connection of speaker after power on.
2. Instant speaker disconnection on power off.
3. Quick speaker disconnect in case of DC on amplifier output.
4. Latch relays off when any fault occurred.
5. Can be used for my dual mono design without hard wiring ground of the two amps together.
6. Can be built from parts I have at home or can source easily and cheap.
7. Is component selection invariant.
8. Is supply invariant from 12V to 24V.
9. Can be configured in a lot of ways so that others can make use of it easily.


From the circuits I found I liked the DIY Audio circuit best that is also used for the boards in the DIY Audio store.
It already fulfills requirements 6 and 7 and 8.
But this circuit has serious drawbacks I tried to get rid off.
I spent lots of time developing a circuit that hopefully does what I envisioned.


Circuit description:

The circuit has following modules:
1. AC to DC rectifier
2. Linear regulator
3. Relay status indicator
4. Turn on delay circuit
5. Latch circuit
6. DC detection
7. Instant off on AC loss


Module description in detail:

1. AC to DC
This is a standard rectifier. Nothing to explain.

2. Linear regulator
This is made up of discrete parts and a very basic circuit. I'm not sure whether this is a good design since I've never done any before and don't know the pitfalls. Feedback from the great engineers of the DIY community is very appreciated.

3. Relays status indicator
I used this circuit from the DIY Audio schematic. I find it a nice solution with the blinken light. Just tweaked component values to my needs. The LED blinks until the relays are engaged and then lights constantly.

4. Turn on delay circuit
I started with the DIY Audio schematic but added a Schmitt trigger for clearly defined switching of the relays because this was missing.

5. Latch circuit
A failure is a potentially catastrophic event. Should the speaker survive the first wave and the relays succeed to disconnect the speaker in time I don't like to give the disaster a second and third chance to ruin my speakers. This is why I designed this latch circuit to keep the relays disengaged after a fault occurred.
The latch is triggered by pulling the node called DC-DETECT to ground. So this can be triggered by any open collector output.

6. DC Detection
Again I used the DIY Audio circuit to start with but found it has two drawbacks:
First it is not sensitive enough. This may be intentional to avoid false error detection.
Second is that it can't detect simultaneous failure of both amps with one going positive and one going negative DC. Murphy will make that happen for sure especially since the DC event is a catastrophic failure condition and everything bad that is possible will happen here.
I also added resistors in the ground path to separate the two ground from each other. Hope this works as intended. For a stereo amplifier I recommend to leave R24 and R25 away and instead double the value of R22 and R23.

7. Instant off on AC loss
I found this circuit on the web and it does exactly what I need. Once the AC goes off the relays shall go off too quickly. There might be too much charge in the power supply capacitors that delay relay turn off. So the AC is sensed and makes the latch trigger once gone.


The circuit simulation shows that the circuit seems to behave the way I intended.
Turn off DC threshold is ~2V.
Relay turn off delay is ~70ms.


Please review the circuit and let me know your thoughts.
Did I get something totally wrong?
Do you have ideas to improve the circuit?


Thank you very much and best regards

Lee


Attachments:

• Schematic as PDF
• Schematic as LT Spice schematic
• Screenshot of operation with latch disabled to show every case that is covered

I came across a stash of these rare vintage NOS Newmarket NKT275 red dots. These are these are the real ones used in the early Arbeiter Fuzz Face. I'm keeping some and selling these. Low leakage, high gain (hFE over 100 but under 200) NOS Q1 Q2 pairs with super low leakage. Two pairs shown for $100/pair shipped.

Quantity of four 50uf 160 volts Rifa capacitors. These capacitors were used in a New York Audio Labs
Moscode 600 Hybrid Tube Amplifier. They were used as an option to bypass the power supply capacitors . The cans are dented but measure fine on my capacitor tester. They also were charged to 50 volts and held a charge just fine

$45 plus shipping and any PayPal fees

Hello all,

I am cleaning up an old Traynor YPM-250 power amp which is functional. Does anyone know the correct procedure to adjust the output bias using R10 which is a 470R pot? Attached are the applicable schematics. I contacted the manufacturer, they had no further information.

Similar Traynor amps such as the PM-300 say to adjust for 10mV across a custom nichrome wire resistor, however the YPM-250 does not utilize this configuration.

Thanks in advance.

Primary 115vac Secondary 6.3 volts center tap at 6 amps. New in the box. I have a pair of them.

18$ + shipping Each

Chicago Standard F-65 115 230 volt primary. Secondary 6.3 volt 5.5 amp center tap Secondary. This Transformer is Really clean and is hermetically sealed.
Tested under 4 amp load. Runs Cool

$45 + shipping

Hello, I am looking for a pair of AD1862N chips. If anyone has it and wants to sell please message me. I live in California, US.

Thanks,
Subbu

Hello! I wonder if I am the only one who seems to be annoyed that the REL Tzero mk3 seems to have too much mid bass that bleeds into vocal ranges… I find the crossover on the back sloping too gentle and would want to modify it to have a more aggressive/sharp cut off slope.

I’m paring it with the Ls3/5a which has a huge 100hz mid bass bump to compensate the lack of bass, hence the leak from the sub is extremely noticeable…

I purchased this El34 amp kit awhile back and just came across it again. Time flies and so did the manual and info regarding this little kit. I was hoping I could get some help identifying it and possible links to supporting information like scats and power supply components. Any help to get this project started would be appreciated. Attached is a picture of the board, but the only identifiers I can find(other than component location) is 2578-EL K91563BS and EL34-V1.2

Here we go again; more Sony V-fet adventures

To save looking
Part 1 : https://www.diyaudio.com/community/threads/another-sony-ta-4650-v-fet-thread.376634/#post6775928
Part 2 : https://www.diyaudio.com/community/...aka-another-sony-ta-5650-v-fet-thread.379125/

Hopefully, not being too clever for my own good I've plumped for a TAN-5550 Vfet power amp frpm Ebay Germany, so hopefully I understood the ad well enough, "Defekt" was pretty clear.
So no V-fets either and it's certainly been worked on at some point - no chimneys installed and some of the screws are missing. But the boards appear OK so it should be re-buildable.

First impression is that Sony made NO attempt to use anything from the TA-5650, although the TAN-5550 could (should?) have been that, without all the extra stuff associated with a pre-section.... Anyway for 'reasons' there is a very different 'class A' board (including a couple of 2SK58 dual fets) and a completely different amp board. It's also entirely directly coupled throughout, which is nice.

As before, this thread is for my benefit in terms of documenting what I've done. Hopefully it's of use to anyone attempting the same thing. But this is how I did it (am doing it) 🙂

I have found the following design on the 'net:

http://xipix.de/elektro/gimos50.html

It looks interesting, although very unfamiliar to me: it's a soft clipping power amp with, by what I read, low global feedback, current feedback and (therefore) high output impedance. It looks very well suited to guitar duties, although I'm not an expert (I can find my way around preamps and I can also design them, but I'm not familiar with power amps).

I've tried deciphering the schematic, but as I said, a lot is unfamiliar to me: the input stage isn't the common differential pair and kinda looks like an output stage? Also, it employs MOSFETs while most of the things I've read up on employ BJT transistors (there shouldn't be much difference though, MOSFETs are biased similarly to bipolar transistors, with the difference that the gate is basically electrically isolated).

Could you please walk me through it and explain to me if and where it can be improved upon?

I recently got a DATS V3 and tested a number of drivers I had. I use to use Speaker Workshop and a Wallin Jig. The results were reasonable to published specs. I just received a used pair of Peerless 830870's, a 4" poly cone in their HDS series. When I tested them, key parameters, such as Fs and Qts were considerably out of spec. Example, Fs spec is 91Hz and measured was 129Hz. I consider 10% reasonable and and consistant with other Peerless models I've tested. It does look like Peerless claims 15% on Fs for this model, but still considerably off from that.

I've also had good luck with measuring Peerless drivers with the added weight method for Vas. The inverted dust cone helps there. I have been using 30g for smallish woofers and 45g for larger. When I try to test these drivers, the test fails because Fs didn't change enough. I tried 30g, 45g, and 75g. This has me concerned there might be some damage to them. BTW, both drivers test very close to each other.

The drivers are used, and see signs of being mounted, so do not suspect they would need break-in. Now, the drivers were shipped, face down against a styrofoam board, compressing the surround. I suspect that this might be the issue and will let them set for a few days, and running tests on each to see if they improve. Is there a test signal that would accellerate this process?

Le and Re measure close to spec, so don't think the voice coil is shorting out. They also pass the "rub and buzz" test.

Any thoughts and what may be causing these issues?

Looking into various options for 4.5" driver to achieve 42Hz -3dB in a 13 x 15 room typical volume 70dB.
Unfortunately the low dB listening doesn't seem to offer much help in gaining extra bass response.
Counter-intuitively, changing port length or closer to wall speaker placement makes negligible improvement. FR is still shelved down below 100Hz.
I have used DSP to depress the midrange. Can't decide if it is better to live with the loss of bass compared to the reduction in sound quality, albeit with less midrange giving the appearance of more bass, that you get with DSP.

1) Baffle step correction passive components.
2)Transmission line - Sibelius or NSMT Bossa Nova.
3) Use 2) 4.5" drivers. One runs full range with no passive components. The second just used to boost FR below 100 Hz. I would feel more confident if I had the skill of Sandy Gross who knows how to design x-overs to focus the sound of multiple drivers to sound like one but with more clarity and impact.
...3a) Run 2 but in opposition. One driver on front baffle and other on back. That would eliminate sound waves from the 2 drivers interfering with each other.
4) Give up and go with 6" like the Alpair.
5) Open baffle.

My limited experience with both transmission line and long-throw drivers both have slow bass and kind of bloated. You get more bass but not the kind of quality you get with 6-10" woofer.

Since the Madisound A26 kit with cabinet doesn’t have instructions, just a list, I thought I’d help would-be assemblers with pictures and some things I learned. This is more suited for beginners. Note: I deviated from their preferences two ways. First, I soldered rather than using the crimping spades and tubes supplied. It should be possible to assemble this solderlessly given what came with the kit. Second, I put the resistors internally. The directions call for attaching them to the upper binding posts. That would have the advantage of trying different value resistors (there are three possibilities, 6 resistors supplied), without opening the cabinet up, so you can change the tweeter level to taste and room.

There are 5 major tasks:

• Line the cabinets with foam insulation.
• Assemble the crossover,
• Wire and install the tweeter.
• Vent stuffing & cabinet stuffing,
• Wire and install the woofer

First, while it says to cut 4x 8.25”x18” pieces and 4x 8.25” x 9.5” pieces, the supplied foam sheet doesn’t correspond to those sizes. So my 18” pieces were 6.25” wide.



I used a glue gun, $18 from Michaels, Fine tip. The long pieces went in the sides, the shorter for the top and bottom. I cut one side one to leave an area for mounting the crossover.



Then I cut the leftover piece to fit exposed areas, completely covering the rear wall except for the cutout for the posts, thinking that damping the woofer rear radiation would be the most important.



Again, the directions say to use the resistors across the tweeter binding posts so you can try the three supplied sets. This would allow you to increase or decrease tweeter output to compensate for a lively or damped room. The pair I built was a gift, so I opted to use the middle value resistor thinking the recipient wouldn’t want to fiddle with it. And, I made the choice permanent by assembling the capacitor with the resistor for internal mounting. The boards were not supplied. Parts express has them. Description: White Perforated Large Hole Crossover Board Pair 3.5" x 5", Part #260-182 URL: https://www.parts-express.com/White-Perforated-Large-Hole-Crossover-Board-Pair-3.5-x-5-260-182



The kit includes crimps for solderless assembly but since these will be shipped, I wanted to make sure nothing got loose so I soldered them. The components can be glued or wired down.

I used 4x3/4" wood screws to attach it the crossover board. I made guide holes ¼” deep in the inside of the speaker. It would be best to lay the crossover board flat, before adding components to drill the holes. Placing tape on the drill bit to make sure you don’t go too deep may be a good idea. Fortunately, the woofer opening is large enough for access of a hand with a small rechargeable drill.



I used the glue gun to secure the components to the board. I passed the other wire under the board, just snipping the red wire to make the circuit through the components, first capacitor then resistor, as the schematic says. I used ¼” number 6 nylon spacers to lift the board from the mdf. Gluing the spacers help them from moving during the inside installation.

I left a space without sound insulation on the upper left side for mounting the crossover board



Wire the crossover to the binding posts and the tweeter. I used red tape to not get confused about polarity.

Gasketing the speaker hole is best done right before drilling. And the material should not be stretched, or the joint will pull away and leave a gap. Just push it against the edge. Note: the pan head screws are for the dual binding posts in the back. Both woofer and tweeter take the allen screws.



First the tweeter. The woofer comes last, after everything else: stuffing the vent the polyfill.



A couple of tips on stuffing the vent. The kit comes with two bars of material for it, but they’re too big and will crease if stuffed. So, just carefully cut them to be a little oversized, maybe an inch too long and ¾” too wide. It also helps to snip a tiny amount to correspond to the rounded corners of the slot.

The hot glue hardens too fast to do the whole thing at once. I did the corners and the short sides, running glue along the mdf. Then I made sure with a hand inside and out that the foam edge is flush with the veneer and all the way to the end. Once the ends are done and you’ve waited for it to harden, say 15 minutes, pull the foam back slightly and inject glue point by point along the long sides, again using two hands to keep it flush.

Tease the polyfill into the enclosure and gasket the opening before soldering the woofer. After soldering, make sure the gasket hasn’t pulled up and drop it in.

Tip: I’ve found that measuring the two bottom screw holes to the vent line was a good way to make sure the woofer was correctly oriented. When the two distances equaled I had it straight and I was ready to drill.

I made guide holes about half the screw width and vacuumed out the mdf the drill pulled up before switching bits to screw down the drivers.

Be sure to tighten the screws a little all around, then at opposite ends. That way you won’t bend the basket. Done!

All things J2 so far...

https://www.firstwatt.com/downloads/J2 Power Amplifier pdf.pdf

https://www.firstwatt.com/downloads/J2 BRO pdf.pdf

https://www.firstwatt.com/wattsnew.html

http://www.6moons.com/audioreviews/firstwatt10/j2.html

Is it possible to connect a full range driver and a bass driver in series, using a low pass filter to make sure only low frequencies are fed to the bass driver?

Hello. Some time ago I gave my Philips CD 304 to an acquaintance to listen to and he returned it to me not working. It said it wasn't opened. The display lights up, the dial spins at normal speed, the display says 00lllllllllllllll in the display and stops. At first I thought it was a power supply problem, but no. So on focus. Not again. I replace the Dac board with a working one and everything is OK. Next is measurement of all electrolytic capacitors, active elements, making new bridges on tables, inspection of all solder joints, but no change. I'm asking for help.

hey everyone 🙂

im searching for an experienced electronics tech in the toronto area

i have some active monitors, with class a/b amps ( all discrete components) , that need some servicing

i have all the schematics and service manuals

event opal monitors

cheers

sw

* if this is not the proper forum for this ad, please let me know 🙂

Good Day everyone,
I'm new here but I'd love some assistance, I'm totally out of ideas. I have an amplifier (A clone/ chinese copy/ remake of a crown macrotech 5002 vz) that I'm currently using for bass. Here's the issue about 2 months ago it started overheating while playing and going into thermal protect (So hot that the back of the amp will burn your hand) . So, I've read a lot and diagnosed a lot. With no speakers or input signals connected, it stays cold. With input signal and speakers connect it runs cold on low to moderate volumes. Only when playing at loud volumes the amplifer overheats terribly. I know i'm not pushing the amp past it's limits as in the past I've used it on heavier duty and it worked fine and stayed cold. Also, I've noticed, that on 8 ohm load it takes longer to overheat (Approximately 1 hour) 4 ohm load it overheats in approximately 15 minutes. I usually run 4 ohm load on the amplifer with no issues

Some of the things I've done:
Checked speakers and cables, even bought brands new speakers just incase, no difference
Checked bias and adjusted and readjusted( lowered and even raised it, no difference
Checked all pcb's for any visible damages, none
Checked output transistors (If you all suspect that failed output transistors may caue this, I'll recheck them)
Checked pre drivers, they seem good

The amp has independent transformers, power supply sections and output modules. only the pre amp section links both boards (Possibly) but the problem affects both channels equally and in the same manner. Its not different for each channel, it affects both channels once loaded the same way

I cannot understand this problem and I've reached a point I don't know what else to check or fix. Any help or advice would be grately appreciated. Thank youuuuu!!!!

Is it possible to purchase TA4F connectors with the circuit board already attached? For Shure wireless lav mics.

My days of thinking I'm clever are long over, so nobody need worry about that. I just noticed that all my power amp simulations go potty whenever I leave class A, and everything I could find on sliding bias seems to have quietly scurried away with time except new products branded as such. Pioneer solved all of class AB's problems in '75 with the 8800, the Levinson 33 sounds good. I get it, but there are no .asc files showing it works at all?

I recently obtained some Exicon fets and determined I would try to use them as best I can. A friend told me class A is dead so I tried to avoid it. The following happened and I can't come up with a good excuse except I started with a "current feedback" circuit and wanted to keep the pulse performance and have less distortion. Please critique or I might be doomed to make a terribly expensive oscillatorsparksmoke. I'll probably do it anyway.

There are some magic current and voltage sources here to make things easier to simulate but the idea I think is pretty obvious. The bipolars are thrown in only because I noticed the latfets didn't like low voltage in heavy saturation so much. They really needed at least 10 volts on them, which is more heat. The "third loop" differential input stage is sensitive to the input filter shift so that the exact values have to be tuned to get the error signal to "null" at 20kHz. Of course the overall feedback resistor must be as well, but you could probably watch the current on the output coupling resistor while adjusting. The differential output coupling resistor value can be tuned for sound, damping factor, or oscillations, whatever you're into. The current on that can come down to some hundred nA of pretty much just the error in simulation. Being off by couple 10uA doesn't seem to wreck it though. I haven't come up with a great way to match the first two loops without a distortion analyzer but haven't thought about it much. Other than that anything else is or isn't real either. Sorry for the scrubby drawing but at least it actually ran the last time I tried. Thanks for looking.

A

My music PC and other audio equipment was once plugged into a surge-protected mains extension lead. But that didn't last too many years (as I understand it these things use metal oxide varistors which can 'go' during higher energy spikes), so I want to get a replacement.

Are there any better (yet still affordable) answers, or do I just buy or make another protected mains extension lead and accept that it (or maybe just its MOVs) will need replacing periodically?

Thanks,
Kev

SOLD I little used , in like new shape.
Two mids = 110$ each
two tweeters 100$ each
and I have the back plate with the volume controls. = 50$
thanks Rick

Hello, I'm going to get an Aleph 3 DIY power amplifier, and I'm wondering if I could in the future use the Pearl 2 phono preamp to put directly to the Aleph 3 the signal of my MM cartridge (obviously through a volume control pot). I would be grateful if you give me an idea of the signal levels involved in this chain and related others (MM/MC, line, power amp input and so on) and necessary gains.
Thank you very much!