Hi all,

The above mentioned subject amp came with blown caps. On inspection found bad transistors in driver board after changing the caps and transistors amp came on and got good oscillations on the outputs. Few days after the amp came back with same blown caps. Any ideas?

This is a very basic question and a topic I'm sure has been covered extensively, but somehow I can't find any information, discussions or guidelines.
The question is this: knowing the rated output power and input +/- supply voltage of a given power amplifier, how do we calculate the maximum current that the PSU for this amp must handle?

For example, I'm assembling the LJM L12-2 power amp. It's 120 W into 8 Ohms at +/- 48 V.
P = I^2 * R, so I = sqrt(P / R) = sqrt(15) = less than 4 A?
Now, the key point I don't understand: does each + and - rail have to supply 4 A, or both of them in total?

My logic and understanding tells me that at any time, the amp is producing either the positive or the negative half-wave of the output, hence, the current is only being sourced by one rail at any moment, so each rail must be 4 A even though on average such a PSU seems to be twice oversized for its load.
Right or wrong?
Thanks in advance for any advice and explanations.

Hi there-

Is this green ring indicative of anything or is it strictly decorative? Lots of old tubes (from lots of brands) had this and I always wondered why. Random sample image attached. Thanks!

Quick question I'd love to have a conclusive answer on. I'm sure that it's splitting hairs but nonetheless...

My amp uses 970/2240 transistors for the input stage and 1145/2705 for the VAS stage.

There is a Marantz service bulletin that actually recommends replacing some of the input stage with their bigger counterparts.

My question is whether it's actually a good idea in the sound quality department? I have new-old stock of the 1145/2705s - about 20 of each so I can hFE match.

View attachment NPNB 2sc2240.pdf

View attachment NPNC 2SC2705.pdf

The higher powered transistors actually have a lower output capacitance, but no noise figure is stated in the data sheet. That tells me they should stay where they were intended for - the VAS stage.

Any insight would be much appreciated.

Hi Guys

Here it sends you right away to drilling section

This will bring you direct to assembly Section..

This will bring you to THROUGH HOLE Section

Here a small Guideline Step by Step, how someone could create his own PCB without having a lot of Technical Knowledge, (same as me).
But before we begin here, a few things which come first.

I use BUNGARD Positive Photosensitive PCB's. There are different Manufacturers, but for me, the ones with that light blue protection sheet are the one which, seems to make the least hassles..

Precautions.:
You are working with Chemicals, so protect yourself as good as you can.
Use thin rubber gloves, use if ever possible a separate room.

Do not inhale fumes from developing solution or while etching the PCB from etching solution.
Use Clean environment.
Work in good ventilated rooms or outside on the balcony or where ever you have lots of fresh air.

RTM
Read the manual of the PCB Manufacturer and also read what can go wrong and why it goes wrong, meaning bad and not usable output..

First Comes First: ARTWORK
But first you need to create your artwork, Single side or double side makes actually not a big difference, except that if you want to make double sided PCB, the fact is if you fail on either side you have to throw away the PCB as a whole..

A few word for manufacturing:
Keep in mind that Temperatures of all the components play a big role but also surrounding temp in your room.
For German manufacturers like Bungard, they give a lead of 20 Degrees Celsius, but not over 22 and not UNDER 20 so be exact there.

Tools you need
A Good BEAM Temp Meter where you can be sure that it measure the temp on 0.1 Degree, never mind if this is Water or Ice, Stone, Iron, Aluminum never mind the color the surface has.. ( there are cheap Temp Measuring tools out there, depending on color these will not read the correct temp.

A few plastic containers, to develop and Etch the PCB-.

Thin rubber or silicone Hand gloves.

A Ultra Violet Lamp or Exposing unit. Minimum 40 Watts

A good Paper Cutting Machine where it enables you to also cut PCB's. (check out Picture 1.6)
You need a even Surface which does not bend.

You will also need a two 3 - 5mm thick Glass Plates, large enough to cover the PCB you are going to make.

You need a Timer or Stopwatch.

You will need a certain amount of Film developing solution then also either Sodium per-sulfate. (etching Solution) Ferro chloride II 40 / 60%

A stove to heat the solution, after wards you can not use that stove for anything else again.

A lot of House hold paper..

A scissor, or sharp knife, and a lot of patience.

Then a good Gram Scale if possible Digital, because all these solutions if you mix them then it's by weight.
And there a gram does matter..

Where
A place where you can rinse the PCB after it has been finished..
Then also a place where you can dispose the used chemicals.
Do not wash it down the drain.
I have 21Pictures to show here. so I need to make 3 parts..

Here, the board I'm going to show, is from today.. PCB is 300x110mm double Sided..
Questions? then just ask.

Some important thing is:
Make sure that the printed side of the Artwork faces the PCB Copper side..
This counts for both the top and the bottom side, that's why it might be necessary that one side of the "Artwork Paper Film" is mirrored.
Usually I mirror the top side.

Heat up the ultra violet lamp prior to use for at least 10 minutes, make sure the lamp surface are free of dust or other none welcomed particles..

Make sure the the DEVELOPER Solution does not exceed TEMPS ABOVE 22Degrees Celsius. Neither the container where it is used in. Also check the temp of the PCB must be in the range between 20 & 22 Degrees, if it is higher then put it in the FREEZER until Temp is acceptable.

Using developer below 20 Degrees Celsius, then the film may will not be developed at all or badly, using temps above 23 and more, will give to a fast reaction to the film and the PCB will be unusable.
Check out the picture where I align, both sides of the PCB ARTWORK, using a simple Window method. Check out the Pics.
Double sided board must be made in one shot, unless you use to one sided PCB and glue them together..

The most important thing is..
THIS IS THE WAY I DO IT, and It works out that way 99% without failures..
But this does not mean that there are not other ways. I know only that way and may it come handy for the one or the other..

Thanks For reading,

Why:
JMFahey, asked me a while ago to write this,I said yes, and here I keep my promise..

Please Note:
Pictures are numbered so these are self explaining.

Proper Exposing Depending a lot on the BASIS MATERIAL

Testing is easy when using different exposure times, and then check out which one is the best.. therefore a small PCB of square inch or 2.5cm x 2,5cm is enough to find out the right Exposure time..

Proper Developing is not over 2 minutes and that is already long. usually it takes about 50 seconds.
Proper Etching can take up from 5 minutes to 1 Hour depends also on the Solution, the temp of the solution and how much the percentage the mixture contains.
Heating up the solution to 50Degrees will speed up the process quite a lot..

The PCB you see will be the second Prototype of the Variable Current Source Class A Amplifier which will run on Idle up to 2 watts with 0.5AMPERE only

Idle is 0.34 Ampere full load depends on the Load seen at the output. 2Ohms is children play for that AMP.
Thanks to MR. Nelson Pass, for his guidance.. and also Thanks to Mr. Rod Elliot, he, with his version of DOZ was the major Starting Point of this.
Thanks to DIY AUDIO.COM that I can be a member here..
Chris Hess

Those of you with experience please recommend some Quick Connects for attaching XO wiring to driver spades and terminal cups. I have 16ga wire and need to connect to .25" and .205" spades.

Also, which crimper should I try?

Thanks

Hi.
Looking for the complete drive unit, including laser assembly etc for a Denon dvd 2500bt blu ray player.
Thanks.

Hello Friends Today Iam Shareing Power On Thump Noise, Shutdown Pop-up Noise Remover Circuit For Tpa 3116D2, Tpa 3118D2 Class d Amplifier Chips. Its Works Very Well With Both Power Supply's Whether Its A Conventional Transformer Power Supply Or a Smps. Pop-up Sound Will Not Present In Power On/Off Times. When Using A Non-Regulated Power Supply Input Voltage Below 18vdc Q1 Transistor Try To Conduct Its Will Enable The Mute For Short Period ( Or a False Trigger ). I Will Drop The Schematics Here, All suggestions And Modifications From Group Member's Are Welcome. Recommended Voltage Ratings Are +18vdc To +24vdc (max). Circuit Can Power From Same Amplifier Power Supply. I Have Upload a Demo Working Video On Youtube For This. Watch Here
Anti Power On Thump Noise // Shut Down Pop Up Noise Remover Circuit For Tpa 3116D2 Tpa 3118D2 Chips - YouTube

Link For Schematics : Mute Circuit-1.pdf - Google Drive.

Hi All,

I use RP3+picoreplayer+HIFiBerry DAC 2HD.

Is there any idea how to:
1. Add chromecast 3 (HDMI output) as a sound source to my system
2. And/or add toslink audio input to my DAC ?

I know thtat I can buy DAC which has implemented toslink input for external sources but stiil doubt how to manage sources switching in my picoreplayer. I found option which allows to switch on audio input but as I suppose it requires restart every time I want to change the source, in LMS panel there is no option to change it in simple way. Ecerything is very simple when I want to manage outputs but not inputs.

Darek

Hi there,
I am close to completing the assembly and wiring of my first point to point SET amp design and I'm almost ready to test the live circuitry. I have a sort of plan to minimize catastrophic failures, but I could also use some advice and tips from experts.

The design is a 6072A + 45 SET with a 5AR4 rectifier (the classic Bugle).

My plan so far:

1. Double check wiring.
2. Triple check wiring.
3. Apply dummy load to output (for a 45, I assume a 5W resistor per channel should be enough?).
4. Turn on system without tubes. Test voltage to rectifier, heaters, and other critical points.
5. Plug in rectifier (obviously after powering off), test B+.
6. Plug in first stage, test voltages to stage 2.
7. Plug in stage 2, test voltage to output.
8. Plug in line source, replace dummy load with sacrificial loudspeakers, set volume to zero, play music, slowly raise volume
9. Wipe forehead sweat and proceed with sound tests.

I only have a couple of nice vintage 45's, would it be worth looking up some cheap ones (worn out, etc.) on eBay just for a first run? Or should I be OK if the voltages are looking right?

Anything else I am missing?

Thanks.

Dear all,

I've just bought a pair of gold MA 11MS, and the plans for the FHXL.
I'm not good with wood working, so I've asked to a friend to built them for me.

Can these plans be used to save wood?

source: https://www.diyaudio.com/forums/full-range/246248-frugel-horn-xl-alpair-10-3-10p-fostex-ff165wk-post6851878.html

I've decided to have it build it as is now, and then implement 390 mm wide suprabaffle ( http://www.frugal-horn.com/downloads/supraBaffle-appendix-draft.pdf ) and 390 mm wide deflector ( http://www.frugal-horn.com/downloads/stealthWoofer-0v8-200309.pdf ) later on to hear differencies.

It will be in birch plywood with surface waxing.

What is the amount of stuffing that I need to insert behind and below the speaker?

250Th tube Amplifier Single end config. Running in Class A2.
250Th Single end config - YouTube

250Th Single end config - YouTube

Outside of the intro thread, this is my first post here. I'm an electrician and I run a small custom furniture design/fab shop in my detached garage.

My furniture commissions are growing and I am spending more and more time in my workshop. My current music setup, when I'm not using 3M Worktunes, is a little Ion Tailgater bluetooth boombox. I have drifted away from a lot of music I used to listen to, because I find it so much easier to concentrate while listening to doom metal (e.g. Sleep, Om, Monolord, Bell Witch). But it all sounds pretty crappy coming from this Ion unit.

I have the ability to upgrade. So I should upgrade.

My shop is 21'x22'. I have concrete floors, one wall is a 16' wide textured metal garage door and the remaining walls and 8' ceiling are OSB wood panels with about 12sqft of window on each wall. It's pretty full of equipment and machines, so I was hoping to mount or hang my speakers from the ceiling, ideally above where the garage door would retract.

So, I guess I'm coming here to see if anyone can recommend a setup that would envelop me in high SPL mid- to low frequency droning guitars and bass. I've looked at PE speaker kits, wacky line arrays, those BIC Eviction monkey coffins, consumer 2.1 packages, and even bose cubes, but I'm having a hard time pulling the trigger on anything without understanding how the ceiling/horizontal mount in that environment changes the sound when I'm reading reviews around the web. If I had to make a decision Right Now, I'd probably buy some BIC RTR-EV15s and a Behringer or Crown Amp, plug in a bluetooth adapter, and cross my fingers. I don't need high fidelity, I just need to *feel* my music.

I have about $750 budgeted for speaker components, sub driver (if needed), and an amp. MDF and other cabinet stuff is on hand and my CNC can handle any wacky cabinet designs you may find.

Available a pair of T330D in need of fresh ferrofluid
250€
Original box

When putting my DAC together, starting out on the cheap I found out that I had a couple of spare 12V/2A wall warts that came from external hard drives lying on a shelf. These were made by Asian Power Devices, and one performed better than the other - one was pretty good with little discernible noise; the other had a high-pitched oscillating whine that was detectable with nothing playing.

Having read on here that Leicke power supplies are good quality, I decided to try one out, and I'm very impressed with the overall package - it's smaller than the wall wart I was using before and barely heats up at all when in use. Best of all, with nothing playing, even with an ear right next to the speaker there is no noise at all at full volume compared to when the DAC is powered off. For the price (around €15 on Amazon) they're clearly a step up from something generic, but at the same time very good value.

Many of these Chinese DAC boards can be powered either by a single +12V or a dual +/- supply. I don't know the relative merits of these or if they make a difference to the sound quality, and I'd love to hear if anyone has any measurements that show that there should be a difference.

For now, though, I'm glad to have found the one or two posts on here that mentioned using Leicke power supplies, and trusted them enough to try them out. Since the posts I read didn't mention their relative merits, I thought it was worth saying something about them. I'm impressed, at least.

Uploading PDF did not work

I give up. Maybe some kind individual can help.

I used to upload files all the time without a problem.

Contacting DIY doesn't work.

Ralf

I have a stark 9-66 tester and a few stark manuals. The 50B5 tube is not included in any manual but the 50A5 is. Also the 50C5 is included in the onboard tester roll chart.

Can anyone guide me to test a 50B5 tube on a stark 9-66 tester? 😱

I apologize if this does not come across correctly, my first post as an attachment. So I am hitting send and see if it works.

hello
looking for a more powerful replacement chinese goldwood 4028 4inches 8 ohms speaker.

I need 100/150 watt
best

My TV sits in the corner of the room on a 20” high cabinet and there is no place for external speakers near it due to the room walls. Things I’ve tried with regular monitors take up a lot of space, come out into the room too far, and are visually distracting.

So I’m thinking about building some very skinny short towers with line arrays that will fit into the corners between the TV and the wall. At the most these would be about 2 to 3 inches wide and about 24 to 30 inches tall. Smaller is better.

I’ve been looking at the Tectonic 2” BMR to use in the array. At only $8 each the cost would be pretty reasonable even I use 12 of them in each array.

I know that such a short tower is not really the best way to implement a line array and it should be much taller. But I’m not expecting the ultimate in performance. I’m looking for something that is pretty good, particularly when watching and listening to opera, but not necessarily audiophile level.

So here are my questions.

Is this likely to give me an enjoyable level of sound performance or is it going to be too short and a complete waste of time?

Is there likely to be much difference if I use 8 drivers rather than 12 in order to keep the height lower? Or is there a different driver configuration than either of those that would be better?

Any caveats or other suggestions in implementing this idea.

Thanks.

I need to repair my Aleph 5 and I've just discovered there's a glass diode on the output transistors PCB, connected neg. rail to gate. It's not shown on the schematic. Doesn't seem critical to the circuit (other than a sacrificial fail, I hope!), but wanted to replace with the same type.

Here it's shown pulled back. Suggestions?

Thanks and Happy Thanksgiving, all.

I have read lots of comments on this cartridge but can find nothing relating to this tonearm.

I'd like to try the cartridge but have no idea if it will be a dud on this arm.
Folk say the cart likes a stiff arm which this should be.
They say it likes damping and I have a trough fitted
But then I read the cart likes a heavy arm which mine is not or whether the bearings are the wrong type.

Turntable is a heavily modded Linn LP12.
Mober one piece sub chassis, DC motor etc etc.

Anyone tried similar?

Thanks Rob.

my SE 10 watt sounds good to me but a friend said that I should be using a 125SE transformer. I think that maybe I should not mess around because I have already done a lot of resoldering things.

Good evening everyone, they gave me to repair an ARC D-52B with a faulty channel, at the output there are 35 Vdc negative.

From a series of tests carried out it has emerged that up to the output of the AM2 analog module everything works (I swapped the driver / final transistor group with the one of channel 1 that works).

In fact, even with the output of the AM2 module disconnected, the output voltage remains negative. I tried replacing the defective Q3 and Q4 transistors (both 2SB555) but without solving. After I checked the hfe of all the transistors of the broken channel but I didn't find big differences between the transistors that the manual indicates as "Matched Set", only by disconnecting one of the 2K7 - 2W resistors the output voltage goes to zero.

I have tried all transistors with both the tester and a dedicated transistor test that supplies the hfe and also with a test circuit with a load bulb and a resistor in base to bring the transistor into conduction, but found no faults.

I think the problem is the difference in gain between the original transistors and the new ones (2SB555). What should be the maximum difference between the hfe of the transistors that the manual defines as "Matched Set"?

What tests could I do?

Hi there,

New to the forum and hoping someone can help.

I salvaged a Rotel RA931 MkII off the side of the road only to find the right channel is dead. Thought it might be the fuses so changed them out but no luck. This was not going to be a quick fix.

So I did some testing:
- R channel out on both direct and remote speakers
- headphones OK on both channels
- visually inspected all components for damage/burnout/bulging caps etc. - no issues found
- started tested some components with my multimeter and found R634 is dead

So before I remove the circuit board to check the underside for cracked solder and attempting to replace R634... am I on the right track and is it worth it?!

Thanks in advance for any help!

Hello,

I am trying to replace the main capacitors from this receiver.
In order to do that I need to disconnect several jumpers.
Maybe really stupid, I cannot get the jumpers loose.
See pictures.
Is there anyone who can help me out?
Thanks in advance,

best regards

I have to change voice coil on Skaaning woofer. Per Skaaning kindly sent me a proper VC and spider assembly. He offered to recoil the woofer for $75. The catch is shipping would run into $200. I reconned, changed surrounds and aligned quite a few drivers but never changed the coil. I figured that if I won't be able to do it a friendly speaker repair guy will do it. It turned out friendly speaker repair guy had a stroke and closed the shop. The main problem is that the VC is epoxied to a poly cone and I'm not sure how to detach it. I know that heating up would soften the epoxy but I'm afraid to deform the cone which is not available anymore. Any suggestions ?

I've bitten the bullet and decided to crimp not solder. But I'm faced with a wide array of terminals (forks, rings, spaces etc), uninsulated, insulated, insulated with heat shrink.

I favour heat shrink, but the pre-insulated terminals are relatively expensive compared to uninsulated.

I was wondering if buying uninsulated and buying heat shrink separate was an actual economy or if I'm just making a rod for my back. I'm not planning on crimping 1000's, more like a couple of hundred, so don't mind if there's a little extra work involved.

Ideas?

I’m having a weird mechanical issue with a Philips CDM-9/65. I’m hoping one of the experts here can help out.

What’s going on ?
When the player sits level it doesn’t read the ToC and shows “err” on the display. The disc keeps spinning indefinitely at what looks like startup speed (around 500 rpm).
When I lift the front panel of the player up about 10 cm (4”) it works perfectly normal, reads the ToC instantly, plays fine with no skipping and accesses tracks very fast.

What I tried so far (with no result) :
Cleaned the lens, including the semi-transparent mirror under the laser.
Cleaned and re-lubricated the swing arm bearing.
Checked that the ribbon cable attached to the laser moves freely without catching anywhere.
Cleaned the disc platter and checked it for any horizontal or vertical run-out.
Checked clearance under the disc platter.
Tested the disc motor independent of the circuitry. It runs super quiet.

I’m at a loss at this point. Any ideas would be greatly appreciated.

I've been running a pair of KEF LS50s, powered by a Peachtree Nova 125SE fed by an NAD M50.2 digital vault/player and an upgraded Rega Planar 1 with Nagaoka cart and Schiit Mani preamp. I've been pleased with the sound with solo voices and small instrumental ensembles even when they rock out. But the LS50s sound congested to me with orchestras and complex overlaying voices.
I decided to explore DIY speakers and settled on CSS' Criton 2TD-X two-way standmounts after CSS told me that the previous version's tweeter was being upgraded. I wanted a little more muscle than the LS50 could provide, but I didn't want to sacrifice detail and transparency for smoothness and comfort.
I am absolutely thrilled with the result. I began this project to get better sound, so that was most important to me. The Critons give me impressive bass, rich mids, and you-are-there highs. I'm still tweaking the toe-in, but I have freakily holographic imaging, even though the image is tilted slightly left at the moment (it's my room, not the speakers). I have the Critons on 28" Pangea DS400 stands (filled with sand), and the combination is both heavy and awkward to move around!
I opted for the flatpack and the upgraded crossover. I'd never built either before, and assembling the second one of both was definitely easier than doing the first! Peter Rawlings is both the world's nicest human being and an outstanding woodworker, and he bailed me out more than once during the enclosure construction and veneering.
The only nonstandard things I did were lining the cabinet with GR-Research's NoRez, replacing the interior wiring with 12-gauge, routing 3/8" roundovers on the left and right vertical edges of the baffle, and the veneer wrap. Oh, and I used hurricane nuts and machine screws to secure the drivers rather than just tapping into the MDF. I chose 10 mil paper-backed bubinga veneer and HeatLock glue, and it was my first veneering job ever. I didn't stain it...just treated it with Howard Feed-N-Wax Beeswax and Orange Oil.
My first hifi love was my pair of Martin Logan CLS electrostatics more than 30 years ago. I'm older and wiser now, but I'm very excited to have discovered romance again!

Bought one of these online, foolishly imagining that it would not be too different to a 621 so I would be able to convert into a guitar amp for a friend. After searching around a bit I discover that it's nothing like a 621 😀.
For a start it's intended for the UK market, so (contrary to what the seller thought) I don't need a step-down transformer to use it in the EU (Belgium). That's the good news ... however

• I found some images of the whole projector, and it has a weird 5-pin connector ("Jones"?) which is labelled "200-250V AC or DC 6 Amps".
• the amp itself has no visible power transformer (whereas the PT of the 621 is highly visible).
• the valve line-up is completely different to the 621, consisting mainly of PL82s.

The "AC or DC" part is well, interesting. Given the strange connector maybe it came with two cables, one using two of the flat pins for AC and one using the other two for DC.
It could be that the PT and/or rectifier was built into the body of the projector and that I need to add a 240V DC power supply. Then again it could be that this model used the very special power supply that B&H apparently came up with for the 640 model, which takes whatever it gets and uses it to power an HF oscillator


Anybody know anything about this beast?

Hi all 🙂

I am starting a new 2-way speaker project and the initial plan was a classic 15" + horn/waveguide. Passive crossover approx. 700/800hz.
It's been my experience that the transition between horn and a direct radiator can be problematic, it sounds a bit disconnected between the two.
I read somewhere, maybe on this forum, that the radiating surfaces should be close in size to provide a better horizontal directivity match.
So if I used a mid-horn with a bigger mouth size compared to the Sd of the direct radiator, this may be the culprit.

So I started thinking about the classic studiomonitors where they would use two 15" drivers in a side by side configuration with a radial horn above.
Thoughts about this, does this approach give a better directivity match between direct radiator and horn?

I want to build my first pair of speakers. And I want to make it a good one, not just for fun. I decided to go with FaitalPro 6FE200 midrange speaker because I've heard two different guys give it high praise (e. g. here), and also because the price is right and this speaker is readily available in my country. But the tweeter from the build linked above is way too expensive and the waveguide used is unobtanium in my country. So I started looking at alternatives that are available. I've found an awesome website with actual measurements of drivers, and after sifting through two dozens tweeters this one stood out to me: Monacor DT-25N.

And here's the Faital 6FE200 measurements from the same site.

Does it look like these two are a match? Or am I overlooking something important? I want the 8 Ohm versions, by the way. I'm a complete newbie in speaker building, it would be great if someone could verify the idea before I pull the trigger and purchase the drivers.

Does anyone know what the Orion 280GX Correct Rail Voltage would be?
Orion 280GX 1st Gen

Hello,
I have an project that i work on for several years (in my spare time). Its an servobias to mentain bias for valve amplifier (output tubes).

Specification:

• work with SE, PSE and PP class A with 4/2 tubes
• size 100mm X 49mm X 15mm (W*L*H) for 1-4 tubes and 81mm X 49mm for 1-2 tubes
• hole size 3mm
• power input 6.3Vac - 12.6Vac
• consumption ~ 28mA
• grid voltage -20V ... -120V (module can handle up to -200V)
• can control an external relay for HV delay (delay can be adjusted, min 5s to 1000s in one second step) to connect/disconnect HT
• small OLED display to show information and setup the module (can work without after inintial setup)
• rotary encoder with push button (can work without after initial setup)
• max voltage read from tubes cathod (K1...K4 inputs) 1V
• can detect valve current runaway, in this case all valve will be maxim negativated and HT relay is decoupled
• with double click on rotary encoder servobias go in "half mode" PDA (to preserve valve life)

Price for 4 tube version is 98Euro and for 2 tube version is 82Euro excluding sipping cost (~ 12Euro with tracking number).

For more info LINK

Hello,

my amp goes in protect-mode. Just connected power + & - & REM -> same state.
I measured the voltage up to the primary winding. After this nothing due to protect.
I dismantled the amp and checked every transistor and they are all ok.

The only bad thing i see that the legs of the transformer (2 on primary and 1 on secondary winding) are a little dark and smells very light burnt.

At this point im stuck. Any help is welcome also circuit diagrams... 🙂

Thank you!

Hello

I have a lot of 500 x2SA991 and 500x 2SC 1844 to sell.

Allso i have 150 2SJ75 and 150 2SK240

Regards

Up for sale are two of the famous DAC Boards from Pedja Rogic. I sell them because I' have found 'my DAC' and there is no need for me to build up theese Boards anymore.
There are allready some ICs like the four OPA861 and the CS 8414 soldered by Pedja on the boards. I also have two TDA1541 in stock.
I have payed 80€ per board and this is what I want to get back. Shipping depends on your location.





Regards, Michael

Okay. So I bought this DAC Kit.

I know I'm not the only one, but I believe my question is unique. Read on...

I was inspired by Łukasz Fikus's Lampucero project for the CS4397 to invest in this beer budget kit.

Now, of course, the six million dollar question is: what is the perfect set of capacitors WIMA, Tantalum, OS-CONS; and in which positions to put them, to get that perfect Bass, Treble, Midrange, and Sensation score of 10, 10, 10, 10 (see article)?

See also the pictures of the board attached below.

Come on you obsessive HiFi nutcases... 😀

Got one of these little gems at the moment. Want to try NOS mode. It is the model with the separate logic board. I’ve followed the usual instructions for converting to NOS but I must be missing a trick and I suspect it’s to do with the logic board?

- pull the SAA7220 (or cut its power and leave in situ)
- connect pins 1,2,3 on SAA direct to pins 1,2,3 on TDA1541 (or jumper them across the SAA to pins 18,16,15 (respectively)

[PURIFI EUROPE] 2x Purifi 1ET400A + 1x PSU SMPS1200A400 Free shipping UP UP !

Hi amigos,

I have 4 Purifi Pack to sell, free shipping to Europe.
NB : shipping at the end of the sale of all packs

contents of the pack :

2 X Purifi 1ET400A modules + 1X SMPS1200A400 Hypex PSU

Price : 730 euros Free shipping via DHL to Europe only please.

NB : last picture is an example of an assembly that I made
Buffers are available from Neurochrome, ATM etc...

Payment : Paypal Only
Shipping free : via DHL express

So somehow I became interested in eliminating driver lobing at the crossover. It looks ugly in polar graphs I suppose..

I tend to be biased against the obvious solutions of using a fullrange or coaxial speaker so the most sensible approach is to use a very low crossover point and put the drivers as close together as physically possible. Basically what happens is as drivers are spaced further apart and the crossover rises in frequency cancellations begin to form on the vertical axis. With many popular designs the listening window can be as small as 20 degrees vertically. Xdir is a great FREE program that can simulate the directivity pattern of a given crossover scenario.

Below is a crude simulation of what this phenomena would look like if say you built a speaker that can color the air in neon green and blue. On the left, 2 point source drivers interact destructively at high frequencies to paint a nice psychedelic blooming neon.. semi-flower? On the right, the same 2 drivers interact well together at low frequencies.



I built a quick prototype to test this idea. I decided to use the Vifa NE19VTA and the HIVI B3S because of their small sizes, low price and excellent reviews on Zaph Audio.



When it comes down to cramming 2 drivers close together how close is close enough? I'm going with the assumption that the lobing effects are negligible when the centers of the drivers are spaced less than a 1/4 of the crossover frequency wavelength. Following that rule Xdir informs us that cancellations will tame the response at 90 degrees off-axis by -3dB. I think that is acceptable even by hardcore audiophiles and as I will show later, real life results are often much better than expected.

The distance between the 2 drivers in my setup is 60mm requiring a crossover point of 1400Hz. I cut a piece of the tweeter flange but the measurements look so promising I think I could've kept it in it's entire glory. The measurements show 30, 60 and 90 degrees off center, 1m away on the tweeter. The on axis frequency response is missing because it looks almost identical to the 30 degrees curve and HOLMimpulse lets me have only up to 3 curves.


I like what I'm seeing (and hearing) a lot and I am going ahead with a 3-way implementation. I'd like to hear some comments from you guys!

Hi. Is there a place I can get a copy of the Linn Slimline smps schematic. This version is the rectangle case marked as MCAS027.

Thank you

Darrel

I have a nice case if anyone is wanting to build a 25watt Class A amp. It is used and some extra holes in the heat sinks and rear panel left over from past projects.

Deluxe 5U Aluminum – diyAudio Store







A slight scuff mark on the front panel which might rub out?

It will be shipped as a flat pack to the mainland UK only at cost.

£300 offers

I'd like to modify my 300B Radiotorn amps to use DC rather than the AC I've been using. I have both 2.5V and 5V versions of the 300B and would like to use both with minor adjustments or switching from outside the amp. I've done this with AC as I just switch between the 5V transformer and its center tap. Works well in this configuration but I would like to get the hum lower.
I have both Rod Coleman regulators as well as Pete Millett's available. I've tried Millett's with a 6.3V 8A transformer and while I can adjust the voltage down from 5V to 2.5V the temperature of the regulator goes up to 90 C when going to the lower voltage. I think that may be pushing things. I have tried the center tap of a 6.3V 8A transformer but I cannot get the voltage needed - 1.9V is the maximum. I have some bigger heatsinks but oddly they have a larger C/W rating - 4.8 vs 3.8. I am hesitant to try those as a remedy.
I need some expertise as what avenue to explore. Should I just use two different transformers and switch between the two? That method adds some pretty hefty iron and expense.

Explanation of "SYSTEM ZERO" is here:
https://docs.rs-online.com/aaa3/0900766b80b458f2.pdf

I am looking for the right naming of the screws from image No 1-3 so as the suited bit from image No 4 (on left).
Image No 5 shows a slightly variation of this kind of screw (also on left).

System ZERO looks like the images No 6-8 (screwdriver-kit, bit and screw)

Such an screwdriver-kit I want to have for the screws showed in image No 1-3.

Thank you for an information.

I need to charge my battery for my audio system .

My power supply only goes up to 13.8 volts .

Is there a way to make a charger using a 7815 regulator or does anyone have any ideas ?

Here is a pic of what the manufacturer recommends to charge the battery . The battery needs to be charged to atleast 15 volts

Just wondering if there was another way to make one since my truck will be sitting another week or so and don’t want the battery to sit out in the garage completely dead while it’s cold outside

I quickly cobbled together crossover for speaker project consisting of Altec 803a (new cone old spider and VC ) a 12 ohm nominal impedance in ~ 4 Cu Ft closed box , JBl 2441 trurextent dia 16 Om in 270 HZ (estimate) Tractrix horn (Sierra , Brooks) and tad Et 703 super tweeter (8 Ohm) Crossover is all 1 st order: 3mH on woofer , 20 uF on mid plus LPAD and 0.1 uF on a supertweeter .
I hooked up DAT's V2 to that bundle and the impedance plot is ruler flat at around d 15 Ohm from 100 Hz to 20 kHz . There is impedance peak at 75 Hz (aroud 80 Ohm) where F3 of the sealed cab is. I must be doing something wrong. It shouldn't be so good should it??

I am looking for a set of Viawave GRT-145W faceplates, I have no clue where to buy these. I already sent a mail to the Russian producer, no reaction.

Good evening gents, after having had a set of Hammond 1650R in my parts drawer, alongside all the parts I ordered for a KT88 push-pull amplifier, I figured it is time to finish this project. However I need some help with determining whether the 1650R would even be suitable for what I'm trying to do.

The design I've drafted is somewhat less than conventional, as I'm using a full symmetrical/balanced design, all the way down to the output transformer. Please see the attached schematic for reference.

I'm aiming for 8R secondary impedance and I'm hoping I can get away with what I have in mind. Basically I'm starting from the 16R configuration, but am grounding the center point (BLK/YEL+GRN) and am taking feedback (-NFB and +NFB) from each of the respective end points of these windings.

By doing this, would I have enough current drive capability for 8R or would I need to consider a different configuration of the transformer's secondary windings? Or would this not be recommended all together, and if so, why not?

I just took delivery of this wall mount shelf for turntables. It is very solid and weighs about 20 pounds (9.1Kg), and my turntable is about the same weight. The instructions for mounting the shelf emphasize how important it is to screw it to wooden studs, but the top row of mounting holes are on 17" centers with a middle hole, and the bottom row of holes are on about 12" centers. There are three holes top and bottom. There is very little chance that all the outside screws, top or bottom, will catch studs.

Has anyone here installed one of these? Should I screw the middle holes to a stud and use the supplied gyproc inserts for the outside 4 holes? The only other alternative I cann see is to securely screw a piece of wood to the wall and fasten the shelf to that, which kind of ruins the aesthetics of the shelf.

Let's consider the textbook cascode circuit with the lower tube in common cathode and the upper tube in common grid connection. Either can be a triode or a pentode.

What about the requirements for the lower and upper tube? Which one should be higher gm? In which position is a pentode preffered over a triode?

While checking for eventual shows in my area in 2022, I was shocked to learn about the death of David. He was not a diy audio member but a great musician as the lead vocalist of the active Big Big Train progressive music group. He died last Friday in an accident. He was not only the main vocalist but a great front man. The music is the reason of our Diy audio hobby. If you like old Genesis style progressive music, Big Big Train is the group.

David Announcement - Big Big Train

Fab

Anyone have a pair of extra M2 boards for sale preferable with the Jfet buffer on the board. I hate to buy the M2X package from our DIY store and then just theow away 3 of those 4 daughter boards.

The DPS is a 12-volt linear power supply considered an upgrade over the stock wall wart power supply for a number of WTL turntables. I've seen nothing but praise for it on the internet, and it is definitely an improvement on the wall wart. I'm running a Fidelity Research cartridge, mounted on a Simplex, into a Softube phono preamp. It can sound great, magical oftentimes.

BUT . . .

I went to turn off the TT last night and I could hear a low level, yet clearly audible hiss. At first I though it was my phono stage, but when I turned off the DPS, that's when the noise floor went down. I had the preamp cranked up for louder-than-usual tunes last night, so that's why I hadn't noticed earlier.

Maybe I should try the Linear Audio Silent Switcher at the Store? It's only rated to 150 mA (@15 volts), but the DPS is only rated at 100 mA, so I guess it ought to work okay.

I had a pair of Tang Band W5-2143 FR drivers on hand for some time and wanted to make a TL box for them but never got around to it.

Open baffle has always intrigued me but the W5-2143 did not seem well suited. Nonetheless I decided to give it a try anyhow and purchased a few IKEA door and drawer panels and used some scrap board cedar for the frame rails with the generous help of a friend with a router.

I pondered on which 12” woofer to use and with my thinking in keeping everything cheap, I selected GRS 12PF-8 woofers and a 100 Hz low-pass filter.

Once all was assembled and drivers hooked up the sound was decidedly unimpressive with the GRS woofers providing very minimal bass response. The Tang Bands were sounding quite bright and not too nice. I decided to remove the low pass filters and see what resulted. It was much, much better! But I was confused.

The GRS are rated 35Hz to 5000Hz and I thought surely that frequency overlap with the Tang Band FR would sound like a mess but it doesn’t at all, rather it is quite clean in the whole lower frequencies all the way up to the higher mids.

I have the DIY OB paired with two REL T-Zero subs and I think it sounds quite good. But I would like to learn why running the GRS pair with the Tang Band unfiltered seems to somehow work? Any ideas, or did I just get simply lucky in the pairing?

Try to be nice in your comments because I truly have little idea what I am doing and just liked the look of the Pure Audio so tried to (poorly) copy them. I think for one, I have a mismatch in the sensitivity of the 12” woofers (87dB) and the 5” FR driver (90dB) and seems I have read the woofer needs to be higher sensitivity but I failed to find an inexpensive one so went with the GRS. Despite that, as mentioned, the combo sounds quite good to my ears, realizing I could very well be biased as I might be forcing myself to approve since it was my “creation”.

I have quite a few PCC88 made by Ei, a small number of ECC88 made by Brimar and Mullard, a bunch of Russian 6N1P and various ECC82 by Electro Harmonix, JJ and Edicron and a couple of Electro Harmonix EF86 for sale. I also have some PCB mounting ceramic B9A bases that are surplus to requirements.

Not looking for silly money. Just need to clear out stuff that is not likely to be used.

Cheers

IAn

No longer wanted or needed. Bit the bullet and ordered a rack of MOSFETs from Mouser. Looking at tekequipment.net for a new PS. Hey, it's only money. . . .

I have a few already, but my crap Korad power supply failed on me (won't do CC and the voltage is fluctuating like crazy). Rather than buy a new PS and a stick of MOSFETs right now, I was wondering if somebody had four reasonably matched IRFP150s for a Zen Mod Aleph J PCB. Two pairs of matched sets is fine, too (using 'em for stereo).

I see a quad of 240s go for $24 + s/h at the Store. I'll be happy to pay $40 + s/h to my place in Austin. That means I'll probably not want to go for shipping from Europe or Asia, sorry.

Now, can anybody recommend a great used power supply that does up to 40 volts @ 5 amps? This time I want something heavy. 😉

I have a Sony X7ESD CDP which uses a pair of Burr Brown PCM58 DACs and has the facility to adjust the DAC for maximum linearity by means of tweaking four small trimmer potentiometers.

The method is to play a CD with a recorded 0dB 1KHz sine wave and observe/measure the distortion of the analogue output. You then adjust the MSB for minimum distortion before moving onto the next less significant bit and so on.

I'm trying to find out what equipment I need to be able to do this adjustment and I understand that I need a spectrum analyser of some sort. A 'proper' benchtop spectrum analyser is a very expensive bit of equipment but I have seen small USB devices for under £100 which may be enough for my purposes.

Something like this one:

http://www.velleman.co.uk/contents/en-uk/p972_Velleman_PCSU01_Mini_PC_USB_Oscilloscope.html

I don't suppose it helps but I already have an Tektronix analogue oscilloscope.

Any advice will be much appreciated.

I don't know if any of you chaps have heard of these guys, but I just took a punt on buying their PreAmp kit:
Classique – Phono Valve Preamp Amplifier With Passive RIAA Using 12AX7 / 12AU7 – DIY Kit – Caledonian Audio
Whilst Caledonian stuff gets great reviews, I don't have quite the same space as the standard enclosure needs, as you can see in the picture below (Top LH shelf is the deck, the highest shelf on the right is for my phono stage):



However, as this comes as a kit (without the enclosure) I figured I could look at making a custom enclosure so I dropped them an email. The owner came back to me and has been really helpful. After a number of emails back and forth, trying to find a way to fit all the components into the space, I came to the conclusion that there were two two options, both with issues:

1. Two Housings.
Separate the PSU PCB and Transformers (which are lovely, but big bu99ers), from the Amp PCB and valves and join the two with cables. However, I have some safety concerns around having a cable carrying HT DC and felt it will be neater if everything is in one case. So we discussed whether a single transformer could work, but I liked the purity of the CA design in using 2 transformers.

2. Use smaller transformers.
So, what about smaller transformers? After all, we are only driving three small tubes. To stay with the CA separate power supply design, and perhaps mitigate the chances of hum even more, use two toroidal transformers? And to minimise space, could the heater transformer be smaller too?
Perhaps a compact toroidal for the HT Anode supply, such as this:
240V/6.3V toroid power transformer – Amp Maker: Guitar amp kits and parts
Then a miniature toroidal for the heater supply, such as this:
60032 | Nuvotem Talema 115V ac, 230V ac, 2 x 12V ac Toroidal Transformer, 7VA 2 Output | RS Components

In the end, we decided that option 1 (two housings) could work if the PSU PCB was housed within the PreAmp housing.
I.E. A separate enclosure, housing the two transformers, building the enclosure from mild steel sheet with a central steel bulkhead, separating the two transformers. Then in the Preamp enclosure, I house both the preamp pcb and psu pcb, again with bulkhead between them. Then, all that is required between the two, is a 5-way cable linking the enclosures, comprising 2x twisted pairs (one for heaters and one for HT), each pair within its own shielded outer (e.g. shielded heat shrink), with shielding only grounded at the transformer enclosure, and a high-quality / low resistance grounding strap between the two enclosures.

However, space is still going to be tight in my application.
Height wise, the distance between the preamp shelf and the overlappling turntable shelf above, means I have 67mm of available height. Taking into account the 52mm for the 220uf 400v capacitor including the power supply board, that allows 15mm for the PCB mount, case and feet. Case top and bottom will total 3mm, feet about 5mm and if I use 5mm PCB mounts, I will have a couple of mm clearance. Tight as a gnat's chuff!

As far as width and depth are concerned, here are 1:1 scale cardboard representations of the 2x PCBs laid onto the original template I sent to the stonemasons who made the slate shelving for me:




As it happens, I was planning to copy the shape of the black slate shelf when creating the preamp case. As you can see; there is just enough room for the outer case (and a bulkhead between the PCBs to ensure EMF separation), with an area behind the amp pcb to site the input/output signal sockets and ground connection. There is also an area next to the power pcb, where I can site the power connections. Currently, all connections are hidden inside the shelving (power and signal in separate channels) so I should be able to also do this with the preamp.

So, I should be able to end up with a discretly powered Valve Preamp that is exactly the same teardrop (ish) shape as the slate shelf, and not a cable in sight!

Once everything arrives and I get started, I will Blog here about my build experience and the results
B

Hello,
I did some analysis of the old TDA2005. My main reason was to find why is immortal. Still have no answer about this but it is interesting chip. It has all the spirit of the late '70s and the early '80s.
There is something like a SPICE model in the attached files. I generated them strictly for the analysis, no pretention for compliance.
I hope someone can find the files useful.
Cheers.

Never connected,
Original box
Price drop
125 eur

Hello,
I have an opportunity to buy these drivers. I don't get to inspect or listen to them in person as they are far away from where I live.
Does anybody know them? What can you tell me about their sound quality and if you can give an approximate value that would be greatly appreciated.
I assume they are high efficiency but the 5 ohm impedance has me wondering if maybe they aren't that efficient (unless it's an easy flat curve)
Are they a nice vintage full ranger?

They seem to be pretty rare. All I can find is this from the Klangfilm.org website:
Fullrange speaker made by Klangfilm in Germany in 1930s used as control loudspeaker in connection with Klangfilm Europa amplifier.

- Dimensions: 24,5 X 24,5 X 14 cm,
- Weight: 2,7 Kg,
- Diameter: 20 cm,
- Alnico magnet (OERSTIT DEW magnet),
- Impedance: 5 ohms

[/IMG]

[/IMG]

Hi,
withdraw from sale sorry

I was looking for examples of EL86 amplifiers, and have come across this interesting candidate.

It is credited to a person called 'lagarto', and is partially described here ...
EL86SE

It has the whiff of Japanese innovation about it, and I'm sure it could work, but could it match a transformer with a UL tap?

If it is an effective alternative, then there are lots of tubes with lower voltage rated screens that could surely benefit from this approach?

It looks deceptively simple. What are the purposes of the 100uF from the primary of the OPT to the EL86 cathode? And the 47R?

Hi folks!

I have a Sony TA-F6B which I recently was given, virtually for free. It's a lovely looking - and by all accounts sounding - amplifier so I'd like to get it working again.

The last owner said it made a loud popping sound one day, and hasn't worked since. After taking the amp apart, it's obvious the owner before him either did some tinkering, or gave it to a tech who cut a few corners...!

I have traced the problem to the PLPS (Pulse Locked Power Supply - basically a late 70s Sony SMPS I think). A heatsink/clamp to four power transistors was not replaced by previous owner/tech so in the end two of these met their maker! Worse he replaced two of the transistors with a different make, and all four are meant to be hFE/batch matched. There is also evidence of lifted solder pads and a jumper wire too in the following pics:





Here's what it should look like with the missing clamp:

http://picasaweb.google.com/895720/SONYTAF6BPLPS?feat=directlink#5325951198508682210

So basically, I need to know what an ideal modern substitute for the 'R' hFE grade, and 'O' hFE grade Sanken 2SC2023 power transistor would be please, as the original devices seem next to impossible to get hold of now.

Any help/advice would be gratefully received 🙂

Thanks,

- John

Hi,

I'm using a 2-way system with an active crossover.

And i get to know about Comb Filter Distortion while searching for sound quality improvement.

Currently my speakers are arranged like below and have the same phase.




Will Comb Filter Distortion occur when speakers are placed like this?

Do I need to change toe-in angle of the speaker to solve this?

Hi Guys,

Im looking for a laptech 5.6 mhz sc cut crystal. I need a replacement for my drixo clock..


Thanks

So I have this amp on the bench.

PS working. Outputs have signal/oscillation.

Not passing signal. No activity on the status led. LED signal seems to be generated on pre-amp board so leaning toward a lack of power on preamp board. Header pins probe most voltages +/-15, +/-5, etc.

Hard to probe pre-amp board while amp is powered, but I did order jumper ribbon cables. Don't have them yet.

Ideas?

Have a little question what the 3 letters mean before 110.
CHR? CHN? CHP?
What does C stand for? What does H stand for? R? N? P?
Can anyone explain it.

I have this setup already running for a month and it's okey... I got sony xplod 12 inch sub inside a tube and a noname boshmann amp. From PC (or TV) via 3.5 mm jack audio goes through a simple wire to wire splitter, to 2.1 PC speakers with a small amplified sub, and to boshmann amp through line level RCA and then to the sub.

Today, I find out that I should be sending audio to high level input...

Would it make a difference if I do? What kind of difference?

I guess I could try before asking questions, but I first need to source a connector somewhere.

Hello.
I do not understand this text on Mark Audio website.

"After design, each driver is individually measured in the echo-free chamber of the Markaudio plant and paired based on these data to within 0.5% tolerance. Each pair comes with individual electrical and acoustic measurements."

What does 0.5% tolerance stand for?

Regards Leif

There is always the question of: "do audio cables sound different?"

Rather than say "yes or no" (..which is pointless, as you've either think you've heard a difference or not), I'm starting off this thread with this video:

The Big Misconception About Electricity - YouTube


(..and though much of video discusses AC as opposed to DC (relative to speaker connection), the most salient point of the video should give some idea that things aren't quite so simple as most would believe.)

It also makes me think a bit more about my proximity to high-power AC distribution lines near my home. 😱 😱

Morning all!

I've just about assembled "Project Mono v0.1" - a mono ADC board.

Featuring

+24dBu input signal
THAT1286 wired in anti-phase per channel
24dB resitor pad for approx -128.3dBu noise into ADC
Subtraction mono in DSP should provide a further 3dB noise reduction
OPA1611 VQ buffer
74VHC125MT & NC7SZ125M5X digital buffers
I2S slave, quad speed mode, high pass filter on
6V DC supply
Ultra low noise 4 channel regulator providing analog and digital rails

DHL should be delivering the THAT ICs today. More to follow!

I'm looking for some various effect circuits to play with and possibly wing up adding
to my audio system. Things like 2nd harmonic generators, sterio width controllers, etc.

Being in kit form or having a PC board available would be a nice plus.

Please list any you may have.

Thank you

I was using headphone output (1/4 jack) on my Yamaha receiver (about "-25 dB" was the volume setting) to XLR input on the XLS 602 amp.
Is that a bad idea?

Testing one channel at a time and then a loud band and sparks flew out of the back where the fans are. I think this happened twice. The channels I was testing when this loud pop happened, no longer works.

What do you think exploded? 😀

Only thing I see there are MJ15024 and MJ15025 transistors.

Everything looks okay. Top of one of the heat sinks next to the top cover looks like something exploded there, but I don't see any electronics near there.

I have a bunch of transistors, maybe I can fix it? I think I might still have some MJ15024/25 also.

Maybe I shorted the cover to the heatsink? I think I was pressing down on the top cover to mess around with the back of the amp.

Just got this, the Denon blu ray transport.
The seller (for which I believe them) said it was all working fine.
Basically the drawer is very slow to open, and sometimes doesn't make it, needing assistance.
My first thought is a belt? But would that not happen over time.
My other thought it may have been stored for a couple of weeks in a non heated warehouse,. Could the cold affect it?
Is it simply a case of letting it warm back up for couple days, or is it worth investigating further, for a belt issue, although on first inspection I cannot see it.
It all works fine in terms of, once the disc is in, and in lovely condition.
It was very very well wrapped, so cannot believe the courier damaged it either.
Thanks all.
It wasn't expensive, so happy to have a tinker.

Hello. I have set up a system with: TPA 3116, connected to a pre amplifier (XH-A901), which has its audio input connected to the signal output of a bluetooth module.

The sound is working but I have some problems like: intermittent hum, regardless of input(AUX,MIC,BL). When increasing the volume, the hum is no longer heard (due to volume reasons, of course).

I tried to separate power from devices with different sources, and the problem persisted. I tried to change the pre amp, and amp and bluetooth module, for others and the problem also persists.

Another problem I have encountered is when turning on the sound, or changing music, a click is returned in the speakers. Follows used equipment and photo.



Placa amplificadora de audio, 120w * 2, tpa3116d2, canal duplo, estereo, digital, 12v 24v, tpa3116, classe d, hifi, diy, modulo de amplificador|Amplificador| - AliExpress



Placa de pre amplificador de tom verificador com ajuste de volume, ne5532, pre amplificador de tom para placa amplificadora|Circuitos integrados| - AliExpress


Placa de decodificador mp3 tela colorida bluetooth v5.0 carro mp3 player usb modulo gravacao fm aux radio para alto falante|Circuitos integrados| - AliExpress




Does anyone have any idea what it might be?


Here's video and photo.
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