Because of an interest, here is the project.
The zip file is in two parts.
Of the file: op-1005.1a.z01.zip
remove .zip
Become the name: OP-1005.1A.Z01

Hello,
50€ plus shipping for the two items.

Hello all! I recently found some old transformers and I am looking to build something from them. Id like to build a couple mic pres based on the Mastering Labs ML-1 but that is just a baseline. Here is a list of the parts i found. If anyone has a schematic, diagram, layout or idea of how to create something cool from these parts I appreciate the info. These items are NOT FOR SALE. Thanks for the help and ideas! Looking forward to making something cool!

Parts List:
1 - UTC LS-56
2 - UTC LS-10X
2 - UTC LS-141
1 - Triad HS-66
1 - Jensen JE-11S-L
10 - Beyer Dynamic 351
6 - Freed 32035
1 - Freed 39940
1 - Freed 39811
1 - UTC A-24
1 - UTC A-39
2 - UTC A-10
2 - Hammond 850Q
1 - Hammond 850N
1 - Sescom MI-29

The bias on a bank of 4 KT88 is running away and causing red plating or worse-blown KT88's.I've checked all voltages and resistors going into the MOSFET. Coming out should be -80 but I'm getting -100vdc.Bias is running away and no where near stable.I'm looking for a drop in replacement since ARC wants me to send the amp in for repair instead of selling me the replacement parts.All I know is it is a NPN enhancement mode circuit.Any help and suggestions would be greatly appreciated. Q6-Q9

Anyone heard of Taylor Speakers (Odin model)? Are they well regarded=

Hello,
I am about to upgrade my audio setup. I did a pair of SEAS MIMIR 10 years ago that I want to change for a floorstander.

Here you told me that Troels Gravesen designed a floorstander with the same woofers and (almost) the same tweeters than the MIMIR. All I have to do is to by a pair of new CA18RNX and build a (quite expensive) crossover.

The thing is that, as mentionned, my speakers are 10 years old and I whish my next project to last at least 10 more years. I am wondering if they could handle another decade?
While I was digging the internet I found Paul Carmody's AMIGA MT, so called "boutique HiFi killer". It seems to fit my needs with inexpensive speakers and crossover.


Talking about my needs: good response at low levels and with better kick and bass than the MIMIR. Price is also a concern as I don't want to go over 500€ with crossover and wood.


Do you see a clear winner between these 2 options?
Do you think that they could be powered by a TPA3255 amp?


Any advices/criticisms are welcomed!



Best

making of :304TL SE - Google Drive
input on E80CC CF direct coupled to 6C45P-E nos bifiliar IT to 6BX7GT
+300/-280V CF direct coupled to 304TL
bias tuning from 6BX7 grids
best for tube life and sound quality 180mA @ 1200V
two set of 3X420V350mA smps in the lower 1U case
then two 5H300mA choke and two D-link dry 590uF1300V
50W A1 4ohm tap 8ohm load
THD1% @28W H3 -60db

Hello world!

For my mono Bluetooth loudspeaker project, I decided to DIY again an active crossover (my first home made was around 1992!). A Linkwitz-Riley of course!

1. My first question is about buffer.

From Mr Linkwitz himself, here is the way to go:


Here is the Elliott Sound Products point of view::


What is the best design?
Especially if I need to add a pot volume before it.

NB: the source is a LQSC BT module. Amplifier: TDA7293 or LM3875 stereo (one channel per speaker). Independent power supply for crossover, amplifier and BT module.


2. For a different project, the second question is about source summation (subwoofer case) and crosstalk issue.

First example, I saw many time, summation before filter section:

I assume RA & RB are involved in the cutoff frequency formula.
Is it correct?

Second example, summation after a stereo design with 2x10K resistors:

Is it not a better way to avoid crosstalk?

Have a nice week.

Pierre

For sale cd player in top working condition with some fine scratches on the side panels, front is without scratches. On top cover is missing one screw. The player was upgradet with some verry good new capacitors from nichicon and on output with russian pio kbg mn. This was made from last owner.The player works perfectly and reed the cds without problem. The original remote is there. More info on privat mesage. Price is 100eu plus shipping.

I understand with computers that standby saves the state of memory so that code doesn't have to be loaded from physical storage again. I could see this mattering for any digital-controlled component.

For an analog component, is "standby" a thing, and does it matter? I've seen "tube saver" circuits that lower the power level through the tubes when the amp is idle. Would disconnecting power to the output stage(s) but leaving the power supply caps charged up be a type of standby? Does it matter?

Yesterday I posted the issue with my Mark Levinson 333 not powering up. I dismantled the unit and found one of the large capacitor "cans" (50,000uF/125V) to be leaking. Please see attached photos. This type (Cornell Dubilier) seems no longer available. Can somebody recommend me suitable capacitors for this unit? Considering the cost of these capacitors: Can I just replace one or do I need to replace all (2 per channel, total 4)?
Thanks!!

I really wish I stocked up on these years ago. Anyway, something with the following characteristics would be really nice:

- compact form factor (mini flange)
- hard dome
- clean behaviour (relatively smooth and with a decent CSD)
- relatively good distortion down low
- not super expensive - looking you, SS beryllium tweets...
- no ferrofluid ideally

Thread topic:
Just thought it would be nice to have a thread about stuff you've done around the house, and the important bit would be to take a picture of the completed job and a celebratory glass/bottle/can of beer (any kind, alcoholic or non-alcoholic, must be Beer, or wine or other type of fermented beverage 😉).
Small job or big, doesn't matter, as long as you're happy to be done with it and feel the need to mark the occasion. 🙂


We moved house almost 1 year ago, so many things we've had to get out of the way first.
The previous owner was not that good on work outside of the house, and I don't know who did the paint job on the terrace, but it's not good. The boards have not been painted or oiled in many years, and I've been peeling off paint on the top of the railing very easily with my fingers, because they used some rubbish acrylic paint, with no prepwork, on pressure impregnated wood.

This is the first time I can remember that I've been able to finish a task like this before Easter was over.
Yesterday I moved everything out of the way, pre-wash, wash with suitable detergent containing anionic tensides, scrub, 2 x rinse.
The floor boards completely soaked up 6 liters of linseed oil that I bought for the job last year, in two coatings. There was nothing left for the stairs (or top of the railing), but I found a small leftover of some kind of industrial "teak" coloured oil that was just enough for the stairs.

Good for the day, nice to have something cool to drink in the nice weather. Need more oil for the railing, and have to consider sanding it down properly first.

Can anyone who's used LM1875 amps describe the speakers/drivers that work well and not so well with them, in terms of impedance loads?

Has anyone tried bi or tri-amping with them, also? Does this give them more capability to drive a general 2 or 3-way?

Hi. My name is Steve and I am the Sales Executive for a PCB Procurement Company called JD Photodata. With over 30 years of experience we have established strong working relationships with both UK and Overseas manufacturers. From design to manufacture, inhouse inspection, and some of the cheapest prices you will find, let us look after your needs and take the strain out of purchasing. Prototypes, small runs and large runs, we can take care of all your needs. Free, no obligation quotes, scheduled deliveries for those larger orders with up to 12 months free storage.

Please feel free to call or email me to discuss any requirements you may have.
01462 452616 or

Hello,

I am a audio noob from Belgium 🙂

I would like to build my first amplifier soon, so I gather a lot of informations here.

I will then ask advices to the community once I will have the start of my project.

See you soon.

I've built two TLSE amps, one for my wife with Electraprint outputs and Edcor PS and choke. The other one for me and had One Electron outputs and Edcor PS and choke. The Electraprints sounded a notch better than the One Electrons. I then changed my outputs to Hashimoto and they sounded better than the Electraprints. If I were to add Hashimoto PT and choke to my Hashimoto output amp, would there be a noticeable improvement?

Hello diyAudio community,
I was amazed by just looking in your projects as a guest a i decided to join the community and would like to do some diy myself.
I'm trying to mod the DX-710 that my father left me, i would like to change the power transformer and the old cd reader(player/lens) that is giving me some problems while reading the discs (skipping, rewinding).
I have so many questions.
Which characteristics do i need to look for the correct power transformer?
Can i replace the cd reader(player) to any other model or do i need to replace it from the same model? Should i be careful about which lens i'm going to buy for it?
I've found some toroidal transformers on aliexpress but i don't know if it's compatible with the Onkyo DX-710
This is the one i found

About the cd reader(player) replacement i haven't got any idea on how to pick the right one and i really hope with your help i will managed to replace it.
I can't just let it die

Thank you everyone for any help!

(Power Transformer Scheme)

Hi all,

I recently contacted Martin Helms, a very kind gentleman from Tymphany Company, upon a message I read on the forum and asked him for a sample of the LPCF600 module.
The amplifier is 3-channel and the power supply is embedded.
According to the data sheet; The amplifier is capable of driving 3 x 300W RMS @2ohm and delivers 0.02% THD for 1khz at rated power (0.003% for 1w). Also, the output noise is only 35uV. These values ​​seemed quite impressive to me.
Outputs can be configured as SE or BTL. This makes it possible to use the module quite flexibly.
Last Friday I received the sample (really fast delivery) and I started to examine the module.
According to my visual impressions, the amplifier is built on 3 pcs of IRS2092. There are 3 x 2200uF average quality capacitors per rail with symmetrical supply. Likewise, there is a medium quality capacitor after the bridge diode at the mains input. There is a two-stage mains filter at the mains input, which appears to be of good quality. There are also filters on the DC outputs consisting of two-stage common-mode chokes.
OPA1678 is used on the input stage (bottom surface).
The amplifier also has a debug module. With this module, you can easily perform on-off and mute controls. In addition, this module has status LEDs and XLR analog inputs.
The amplifier module can be easily installed and used.
I tested the amplifier with my DIY ES9018S DAC and Wharfedale Diamond 9.6 speakers. There was no preamplifier or volume control unit in between. Other than that, I did not use any special equipment, cables, etc.
As for my listening impressions;
I can honestly say I was quite impressed.
The amplifier has a very detailed and wide-stage sound.
Bass, mids and trebles were just right. (Diamond 9.6s are known for their lack of treble)
I did not observe any audible distortion.
There is no audible noise of any kind in both mute mode and play mode (with my ears sticked to the tweeters, even inputs were open; wow !)
I haven't done any electrical measurements yet. So I may add to my review in the coming days.
That's all I'm going to say for now.
I highly recommend you try it if you have the opportunity.

Drivers & Amps - Peerless

Complaint : flashing red light after 10 minutes of play.
Trolling around internet I see vague mutterings of capacitor problems.
Have extracted SMPSU and tested electros with ESR meter, found none of
them spectacularly bad. Any ideas appreciated.
M

Nice amp my design.

This is a theoretical post. Nothing has been made. This is also an uncertain post, which, is based on some myths, which, may or may not be true or may have an insignificant effect. However, some of the ideas may be used ( changed or not ) for Class D amplifiers.

Myths :

Because of lack of information, the proposed controller is made after some myths, made up by the author. Whether these myths are true or false is unknown.

Myths :

1. Continuous is better than discontinuous as far as the noise is concerned.

2. Gradual and slow switching of the primary is better than fast switching as far as the noise is concerned. Instead of the whole, suggested here, transformer, RC filters can be used before the transistor to allow slow switching.

3. Higher resistance ( Rce ) in series to a switching primary is better than low resistance as far as the noise is concerned.

4. Because noise can proliferate from the auxiliary and or primary coils through to the secondary coil ( s ), a controller, made with analogue, audio parts and without any component saturation is better than a controller, made with digital parts or non audio analogue parts or parts which can go in saturation as far as the noise is concerned.

The idea, therefore, is to make a flyback transformer controller with low noise, audio components, which, switches the control transistor of the transformer’s primary gradually and slowly within the period of the switching frequency of 50KHz to > 100KHz. The controller must perform a very gradual switch of the control transistor. This may or may not reduce the noise and may, even, increase the noise. Unknown.

Here is the document :

An Idea for a Controller for a Switched Flyback Transformer Power Supply - Google Drive

The schematics are in the addendum.

Hi,

We have the below setup
Mixer: Soundcraft signature 16
Amp: Crown xli 2500
Speakers: 2 x JBL JRX 215
+ sufficient speakon and xlr connectors from neutrik

Now, I need some guidance on choosing the right cables for connecting all these. I am planning to solder these connectors by myself. Please suggest the cable specification.

I have a few things available to anyone interested.
I'll take any offer + the cost of boxing & shipping.

Also happy to trade for exciters.

Items:

• Bel Canto 1.5 DAC (I don't have the original power supply but I do have one that works.
  
• Pair of Beyma TPL150H drivers
  
• Pair of passive crossovers from the PureAudioProject Trio15 Beyma.

ITEMS NO LONGER AVAILABLE.

Thanks to everyone for their interest.

Hi,


Anyone recognizes the model/manufacturer for this audio jack?

It's a 4 contacts-TRRS type, no switch. SMD (L/R contacts, i.e. T and R1) and TH mounting (ground/mic contacts, i.e. R2 and S). Also comes with extra mechanical support in the form of a silver metal band with TH mounting to board.

It's used in quite a few digital audio players (Fiio, Cayin etc.) but after rather extensive search (Mouser/DigiKey/Arrow/Farnell/LCSC/Aliexpress etc.) I was not able to identify it.

Eventually (actually just a few mins before writing this) I think I think I may have identified the manufacturer (G-Switch - 轻触开关-防水轻触开关-TYPE-C连接器-TYPE-C母座厂家-品赞电子) and I even found a connector listed on their website that resembles very closely the one in question (PJ-0275S00 - 3.5四极6PIN带铜套贴片镀金耳机插座_品赞电子), however not the exact one I am after. Nor was I able to see one for sale.

I guess I'll reach out to G-Switch and assuming they reply will find a way to source a replacement for the connector I am interested in, however I thought it does not hurt to ask a question here as well. Thanks

Hello,
I have acquired said transformers and I'm looking for an idea what can I use them for. I'm a newb in transformers so any help is appreciated.

That is how much in the Fed balance sheet. I would think at some point it will matters. I suppose it already matters since people are paying more for everything. It's unprecedented in modern time. I don't think anyone really know how through which mechanism can the FED unwind its massive balance sheet. It is a bubble. Can the FED keep printing? Nobody really knows.

I have a reel of these, RN60, 1k, 250mW, 100ppm.

while the 1x/100x price at Mouser is $0.500/0.185, I will part with 25 pieces for $5.00 which includes shipping. Unfortunately only US as USPS rates ex US are outrageous.

I have just been given this:



It's a Hitachi TRK-3D8E boom box / guetto blaster / brixton breifcase.

Whatever you call it, it sounds pretty good. It's powered by either mains, or what looks to be 8 x Alkaline size D cells, which would make it 12V.

Being that it's full of retro charm, I would like to modernise it's capabilities a bit, whilst retaining the retro look and feel.

Initial ideas are:

• Different power source.. motorbike battery? Lithium cells?
• Add bluetooth connectivity (or similar)
• Add additional drivers - theres a LOT of space internally from what I can see though one of the vents
• TPA3118 chipsets run on 12V....

There's an aux in on the back which I have been using with my phone and it works well.

Problems I have noticed:

• There's a bit of hissing coming through - faulty equaliser sliders?
• Cosmetically, it needs work!

I'm asking myself things like:

• How much do I gut it?
• Do I preserve things like the equaliser?
• Could one of the tape decks make way for an OLED screen?
• Charging circuitry for the batteries? (there's a switch on the back to choose AC/DC so it's not designed to charge anything)

I welcome any and all suggestions on what to do with this and how to go about it!

Very quick question - does anyone have a rough ESR value for Auricap XOs?

Up for sale here is:

1. FIFOPi Q2: like new, never been used because of the lacks of time to finish the project.
Price: 110€

2. Isolator Pi : very good condition
Price: 20€

3. Raspberry Pi 3B with OVP: very good condition, hardly used
Price: 20€

If buy 2 items or more, bonus one board of ShieldPi or I/V Std (bare board) & small discount.

First, my appologies, I may not know the best formatting as I'm new to this forum, so I hope my post is functional enough. If not I'm willing to learn!

I have an audio repair person helping me with some upgrades for my Yaqin MC-13S. I am also getting started with DIY audio and am planning to try a preamp soon - but I'm not ready yet and I want my amp functional before the holidays 🙂 Also, I might not have gotten the specs right from my repair guy. I think I'm close, but looking for help there too.

The upgrades we are attempting are listed here... although the documentation is a bit sparse:

Yaqin MC13s Upgrades and Switchable Feedback Installed – AD Audio Consultants




The quick version is that they made these changes:
Elna Silmic bypass capacitors,Mundorf ZN coupling capacitors, and Takman carbon film resistors, and a switch to disable negative feedback.

My repair person gave me the parts I would need, although I wanted to double check because he's ultra busy - and I want to make sure I understand as best I can.

1) Coupling Capacitors: .47mF 600v(or more) x 4
2) Bypass capacitors: 470mF 25v x2
3) Grid Resistors: 2w (or 3) at 820 ohms

Click to expand...

First - could someone confirm this is accurate from this schematic:

Second I was planning on:

Mundorf Supreme SilverGoldOil caps
and Audio Note Silver non-magnetic Resistors (820R Ohm, and 2Watt).

Click to expand...

Are these decent choices?


Thank you in advance for looking over and helping me.

This is my first post here, so please be gentle. I've searched around the forums, and either the posts didn't exist or I am really terrible at coming up with the proper search terms(probably the latter).

First of all, my goal is to design and build a stereo single-ended tube amp from scratch. I'm a software architect and my electronics engineering extends, unused, back about 2 decades ago. The rust extends through the paint and most of the body, and is barely salvageable.

My training 20 years ago barely touched on tubes, mostly transistors. Finally, I'm trying to do my modeling on LTspice. I've seen mixed reactions to this on the forum, so hopefully someone can help me out.



A couple problems I have to start, and hopefully someone can give me a kickstart.

1) The way that LTspice models transformers. I'm sure anyone knows that it links through the K directive and you must provide inductance for all the coils. I e-mailed Edcor(seems to be the cool guys to use) about their power and output transformer values and they replied that they don't even know - at least they were able to get me the turns ratios for their output transformers. I didn't get that far yet, I was trying to model a power transformer just based on turns ratios. The problem is that LTspice requires inductance to define the coils, so I had to make up some numbers based on unknown characteristics. You can see that in the schematic. I was not able to find some typical values to make this work out like I wanted. I have no idea what typical inductance values a power transformer may have, my training only involved turn ratios.

2) I wanted to use a tube rectifier in my model - specifically the 5AR4. I saw, attached to this forum, the .inc model for this rectifier, but I'm unable to find a schematic symbol that works with it. Has someone made this and I've missed it?

3) This may take a bit of an LTspice expert to look at, not that I am one at all, and it may dive into #1 and my gap of knowledge after 20 years of non-practice. In the schematic, I have L4 pumping out to nets H1 and H2, supposed to heat up the filament. This just isn't working. The plate voltage stays flat. The voltage and current oscillate at 60Hz. The analysis across the lines show ~6Vac and ~200mA, about 1.2W. It just isn't "heating up" in the model. If I provide a direct AC voltage source(inserted into the schematic instead of sourcing off of the transformer), it "heats up" after about 4.5 seconds and works normally after that. I am having a lot of trouble figuring out what the difference is to the software.

Anyway, I'm welcoming all sorts of feedback(solicited and unsolicited). I'm looking at this as a learning adventure and to refresh a passion I've had and long lost.

Thanks to anyone who replies.

Im looking at the specs of Faitalpro 6FE200 and it suits my needs well, but does it compare to something modern with demodulation rings? I want to replace my Seas Excel w18 driver with something more efficient and with no insane breakup peaks. (I've also looked at the SB Acoustics 6.5" MW16P-4, but I think I will have a hard time getting that into a 3. or 4. order acoustic high frequency roll-off at about 3kHz without some serious crossover work.) I need to to match my 4. order acoustic Neo 3.0 hornloaded ribbon roll-off.) With the 6FE200 I hope I can use a 2.order lpf filter and get 3. order acoustic roll-off with some trial and errors with REW. So any inputs on how good sound one can achive with this driver, or links to mods done to it would be helpful! I could put a phase plug and some copper on it if anyone thinks thats a good idea. I'm not good at crossovers, but the 6FE200 looks easy to work with. I plan to use a sub up to max 2-300Hz with dsp and the upper limit needs to reach atleast 5kHz. The off -axis respons on the 4 ohms version looks very good in the 4kHz area. I can get this driver cheaply in Norway so I'm considering to try it out 🙂

Dear friends, i have a problem in the radial correction circuit. The player reads CDs TOC with all but most when it gets to tracks 8 9 10 .. the mechanics start to make noise and the audio distorts. Checking the measurement points as per the service manual, I realized that I have wrong measurements in two points. Pin 1 of Q214 (LM324) in Stop measure + 500mv. instead of -7.1V and at Pin 14 of Q215 (LM324) I measure -3.05V. instead of -11.4V. In Play the measurements in these points are like the manual even if not stable. doing various tests I realized that by disconnecting the radial error connector on the CDM0 board, the measurements listed above return to being perfect. The mysterious thing is that I first replaced the servo board then also the CDM0 drawer but the problem remains the same. If anyone can give me any suggestions you will be grateful, I am really heartbroken.

Thanks!

I enclose an image of the circuit.


2021-11-08 08_45_25-1.png - Google Drive

Hi,

Trying to figure out what are the relevant parameters for an Onken enclosure?

EBP is helpful when working through Horn/ported/sealed types of enclosures.

Any thoughts on what the pertinent parameters are when designing an Onken?

Thanks!

Per

Looking for the pivot portion of an empire tone arm for a DIY project. would happily buy the whole arm too. prefer a 990 with anti-skate built in, but open to options. If you have a broken one that needs rebuilt, that works fine too. It will save me starting from scratch on my project.

Thanks!

As I build my class A simple amplifier, and delve into the current-controllable-variable-resistor concept which is the transistor, I keep wondering if a similar device could have been invented earlier? This is for audio amplification applications.

Has anyone come up with a variable-resistance relay that will do a similar job? Of course reliability will not be the same as a transistor, and performance may degenerate. Maybe a motor controlled by a small current moving a mechanical potentiometer?

The circuit I envisage is a simple amplifier circuit. (Single ended etc)

Alternatively, could a simple oscillator circuit using a capacitor be set up, with the input audio somehow made to vary the pulse width of the signal, this in turn used to create an amplified signal at the output sort of a class D without the transistors?

The first idea is within the realm of possibility, and I intend to try it out sometime. The second one...

There is also the magnetic amplifier but sound quality is said to be not so great, aka distortion.

Selling a licensees for AFMG EASERA 1.2 acoustic and electronic measurements software for the professional. I purchased this license when it was version 1.1 but has understand it buyer will download version 1.2 and it will except the license. I would like £400 for the license, but I may except a good offer.

For more information about this software here's the link

AFMG EASERA | Ahnert Feistel Media Group

I emailed AFMG asking if I can sell my licenses for EASERA and the response was.

Hi Mark,

Thank you for getting in touch.

Yes, you are allowed to. Please notice that in order to transfer a license to another company, the following is necessary:

Please send some kind of written proof/confirmation to AFMG using the stationary/letterhead of the former company.
This should include:
The name and full address of the new company
The license IDs that shall be re-named
Name and signature of authorized person
Go to our pricelist on the internet: [link removed by eBay]
Purchase the Service Charge (50 EUR) for every license that shall be re-named.
Mention the license IDs in the comment field on the checkout form.



We will then process your request, close your license and generate a new license to the buyer.



Best Regards

I have this Sansui AU 2900 which I had all the capacitors replaced.
The problem is that the left channel continues to produce crackling. I have already taken it back to the audio store technician for a second time and after 3 months of waiting they told me that they tested it for a long time and in the end it was just a fuse making a false contact. The technician also told me that he checked the transistors and put plastic and new thermal paste.
The whole operation to date has cost me 700E and in the gallery you can see all the capacitors replaced. I took pictures of other details of the board and the transistors. From the gallery you can see the first 4 photos (before) of the original state while all the others are post operation (after).

Unfortunately, I lost confidence in the technician who did the repairs, and could probably have spent 700E on a new, modern amp.
I am very despondent and would like someone to help me understand and maybe try to repair it myself. I'm not an electronics expert, but I do have good dexterity.
If you need more details, I am willing to send more pictures.


Thanks to anyone who can help me find a solution.

Edit 1: I've seen in other thread and forum that this is a common issue. I've downloaded the service manual and first thing I learned is about bias. Comparing the pictures before/after it looks like that was not touched. Is it possible that after recapping the full unit there is no need to adjust the bias? In the service manual they suggest to check every 3 months. I have a multimeter and I think that this is the first thing I'll do tomorrow morning, but not sure it will fix the issue.


Edit 2: the cables I'm using for connecting the speakers are custom; I made them by myself using an high quality 4mm^2 section cable . I'm not sure if I'm doing the right thing but I'm connecting them this way with spades at the very end. I realized only at the end that they are a bit bigger but they sound great.


Edit 3: I've recorded 2 videos:


- After the recap
- Today, when I got i back home and the technician told me that was only a fuse...


As you can see on the left channel the sound is completely distorted with lot of crackling.


Edit 4: I used my multimeter to adjust the bias. I was able to adjust the right channel to 13mV but I have alway 0mV on the left one. I measured several times, ampli was running for 30min or more, speakers connected, volume at minimum and I can measure 12.9/13/13.1 mV always on the right channel and always 0mV to the left.


Edit 5: I let the ampli cooling down and I'm able to measure the on both channel ~13mV and there is no distortion. I'll redo the measure in 30min.


Edit 6: I listened at low volume (3 on the knob) for half an hour. I adjusted the bias to 13mV in both channels. No distortion. I continued listening at low volume and then increased the volume to 5. As soon as it started to distort, I turned the volume down and measured 13mV on the right channel and 0mV on the left channel. @anatech Is this still related to TR03 TR04 and IC01 and IC02?

Yes, I'm looking for a NPN type that has:

1. as high hfe as possible
2. high transconductance at around 100mA
3. capable of more that 1W
4. Will be run cascoded - no particular voltage requirements.
5. Reasonably easy to get.

Any tips?

Thank's

Morning all - Consensus is that the phono stage in a Pioneer A400 is a bit rubbish and I’m looking to improve on it either by modding the internal one or adding an external one. Found the schematic here although this one does also cover the A400X: PIONEER A400 A400X Service Manual download, schematics, eeprom, repair info for electronics experts

I have so far changed the caps in the phono stage and fitted an OPA2134 - Nichicon Muse electrolytic coupling caps of the original value, polystyrene feedback caps and 1000uF PSU caps (Panasonic FM I think?)

Does anyone have any recommendations for further improvements - the above have already made a really big difference (with the caveat that the amp is ~30 years old and had never had a recap before so may just have benefited from a simple recap). Would a fancy opamp like a Burson or Muses be worth looking at in such a simple circuit?

Coupling caps are 22uf so not sure where I’d go to upgrade them further.

To follow on from the above, would I be best off for the time and effort just purchasing an external preamp? With the mods done I’m not really sure what level I’d need to look to make improvements over what’s in there now.

I have built an open baffle floor standing speaker, that is going close to the wall behind. Because of this I want to absorb a lot of the rear radiation.. I have got a cobbled together collection of cushions and towels which sort of work.

Part of what I want to do is to put 1 to 2 inch thick absorbant panels on the rear of the baffle, the inside of the wings. I thought Rockwool, but there is a problem. I have bronchiectasis and anything that sheds particles is a nono. Which rules out glass fibre.too.

So, can anyone suggest something that would suit my needs. (I will probably use raw wool in the free air behind the speaker)

I'm hoping this thread is relevant for novice speaker builders like myself.

I've built a 5.8 ft3/96 liter box (35" x 16" x 15") well stuffed box for a 12" Acoustic Elegance Td12h-4 woofer mounted center top and a 4" diameter x 8" long port placed center around 5" from the bottom.

sub box



My close mic measurements from the woofer are fine and from the port, what you'd expect. Together they would suggest a fine response curve.

response curves



At 1 meter, I'm seeing something fairly catastrophic. Blocking the port does not change the response.

The speaker is 10' from the back-wall, and projects into an open floor plan around 50' long. Me and my pocket clio are around 2 meters from the source.

I'm looking for general theories that explain what I'm seeing. Could I have made any novice design mistakes?

Thanks so much.

Does anyone have any experience troubleshooting a Universal Audio 2-610? Picked up a broken one and was looking for the schematic - can’t find it anywhere!

Hi all,

After several years away from audio things because of work, I now found the time to be back to this hobby 🙂

So some days ago I was able to acquire a System two 2322. The price was very interesting and it still was perfectly calibrated and in mint condition, functionally and aesthetically. And with its PCI card.

But there is no free lunch, and it is has no options.

Searching on the forum I found out that some users were able to design (and sell) a brickwall AES17 compliant lowpass and an AWGT filter

I'd like to have at least the IMD board for measuring DACs and if someone had one to sell I would buy it for sure. It would be great to find an S-AES17 option too [I know there is a guy that worked at AP that had probably some of them to sell @Audio1Man is his nickname, I emailed him some days ago but still got no reply]

So question time:
1) Are IMD and S-AES17 mandatory tools for testing DACs? [I still have to build some experience into audio devices testing]
2) I saw that the DSP D/A generator has IMD tones generation but with no IMD option the Analog Analyzer has the IMD function disabled. Is there a meaningful way to use the IMD D/A tones with the Digital Analyzer, DSP etc making the IMD option not necessary?
3) Is a 2322, despite old, an useful tool to evaluate digital devices that have today performances that were not existent when it was designed (48k digital analyser is a limitation already with 96kHz and 192kHz being common today)?

I am just evaluating if I could get something meaningful from it or I should trade it in as soon as it has some value and wait to gather money to buy something more actual like, say, an APx515 or a Prism M1 for example.

Thank you for valuable opinion!

I saw these old cabinets posted in a discussion group on Facebook, apparently originally these used an upward firing 12” fullrange speaker.
Curious if anyone tried to diy similar designs? Do they work well?

Hello, I need to do my 1st design attempt of speaker with Jantzen 8008 HMQ and SB Acoustics TW29BN-B-8. No change in drivers is possible (because I already have them)

Requirements:
1) two designs, one base and one floor. I have chosen so far 58X36cm baffle for stands and something like 110x30 for floor.
2) Efficiency preferred > 92db but >90db is ok
3) Room is like 24 sq.m., curtain behind the speakers, thick carpet on the floor. Room is only for listening.
4) Could be bass reflex or not.
5) Conventional design, this is my 1st attempt to build speakers
6) Would prefer to have simple crossover, unless proven needs to be otherwise.

For starters, I worked with SpeakerSim and VituixCAD.

I attach response file and graphs I have so far.

INFO: I have used two pairs of speakers so far in the room: Dali Oberon 7 and now Focal 948. Impressions:
Dali: Good bass, good treble, they create a stage and vocals are good.
Focal 948: Enormous bass and have an excess @50-60Hz. Bass is moving the couch. Vocals excellent really, enormous stage. very good detail but not excellent. Highs are very warm but sometimes I feel I would like more. Maybe it is because bass is so much.

So, aim is not to have that 50-60 Hz room spike, keep the voices and stage of 948 and have somehow better highs.

My 1st crossover for the small box is only two coils and one capacitor.
See attachments.

Now waiting for your advice

I would like to share my setup which is used for AirPlay, and nothing more than that.
My equipment is as follows:
Purifi EVAL1
smps1200a400
SMSL SU-8s
Raspberry PI4
Elac FS407

My goal was to achieve the greatest possible user-friendliness, while not compromising on quality.

The first thing I did was buy two of these: TRU COMPONENTS 718672 3.5 mm audio jack Socket, vertical vertical Number of pins: 2 Mono Black 1 pc(s) | Conrad.com
One connected to the smps1200a400 (GPIO / GND to PIN J5.1 / J5.5) and the other to the Raspberry PI (GPIO / BCM pin 21 and GND39) then just connect the PI to the smps1200a400 via a minijack cable
Notice my 5A fastblow fuse, unbelievable Ghent does not add it 🙁



My wish is that my PI should turn on my amplifier when music is playing, and turn it off when nothing is playing and after 5 minutes.

And here I must admit that I came across a difficult task. Because I can not code anything. And I could not find anything that lived up to what I want. Yes. Volumio has a plugin, it only works during play / pause and not when the music stops by itself.

So ... I had to get started 🙂

The following is code without explanation. The purpose is as written to get my amplifier to turn on when music is playing and turn off when no music is playing and after 5 min

Download, install Raspberry Lite Raspberry Pi OS – Raspberry Pi

Write an empty text file named "ssh" (no file extension) to the root of the directory of the card.

Create a text file called wpa_supplicant.conf, and place it in the root directory of the microSD card.


From Mac via terminal
ssh pi@ipadress
Password:raspberry

Change the password!!!
sudo raspi-config

******************************
Update Raspiberry
******************************
sudo apt-get update
sudo apt-get upgrade
sudo reboot
******************************
Install shairport
******************************
shairport-sync/INSTALL.md at master * mikebrady/shairport-sync * GitHub


git clone GitHub - mikebrady/shairport-sync: AirPlay audio player. Shairport Sync adds multi-room capability with Audio Synchronisation
cd shairport-sync
autoreconf -fi
./configure --sysconfdir=/etc --with-alsa --with-soxr --with-avahi --with-ssl=openssl --with-systemd
make
sudo make install

sudo systemctl enable shairport-sync
sudo systemctl start shairport-sync

******************************
Shairport settings
******************************

sudo nano /etc/shairport-sync.conf


******************************
On/off on play/pause/music stops via GPIO
******************************

sudo apt install python3-gpiozero

sudo usermod -aG gpio shairport-sync

sudo mkdir pyh

cd pyh
sudo nano start.py


sudo nano stop.py


sudo chmod +x pyh/start.py
sudo chmod +x pyh/stop.py

******************************
Off on boot via GPIO
******************************

sudo mkdir logs

cd pyh
sudo nano launcher.sh


sudo chmod 755 launcher.sh

sudo crontab -e


I can add if you need 3V, and not 0V to trigger your smps to turn on, then swap these start.py and stop.py so it looks like this:


sudo reboot
Play and forget

I propose a simple differential BJT amplifier as a soft peak limiter combined with additional asymmetric H2 distortion that is generally attributed to tube sound.
The symmetrical output drives directly the inputs of TPA3255, for instance. Setup properly, PBTL-output level is limited below the class-D typic clipping.

The LTSpice simulation shows the contribution of the emitter resistor to H2 and may intrigue you to play around with different values.
Enjoy😉

Hello.
NAD 3020 integrated amplifier.
Model with 4 big caps in center.
Amplifier works fine.
The sound is clean,very great engine.
But right channel crackling.
Volume on zero.... crackling.
Pre amp.....no cracks
I replaced 2 power transistors....no success.
No bad soldering,no suspects parts.
All potentiometers and switch was cleaned.

This sound is similar when you fry bacon.

if I turn up the sound, then this noise is not heard.

Regards

Service manual

NAD 3020 SM Service Manual download, schematics, eeprom, repair info for electronics experts

PP Choice - Baby Huey or Engineers Amp

Having spent most of my time with Class A amps I'd like to take a journey into hot glowing valves.

I have Huey boards but the Engineers amp board is cheap too. I wondered would I get most from Baby Huey EL84 vs P Millet's Engineers amp?

Barbouri implemented a nice PCB and design of Scullcomm's Milliohm meter.

Milliohm Meter Version 1.5 - Barbouri's Electronics Projects



scully incorporated it into an update:

Milliohm Meter Update – Scullcom



I have just made the Scullcom version using the 1.4 boards. (didn’t notice there were some 1.5’s!.)
Just finished it and its working fine. I ordered the 1.4 boards by mistake but implemented the 1.5 changes.



Getting hold of the 2V voltmeter (YB5145B) was difficult to find in the UK. I could only get 200mV version. After a lot of mucking about I found a way to convert the 200mV to a 2V version.

1) Remove 2 resistors, RA and R1,

2) Put a 100k at R1 and a 11K at R2.

3) Then change the decimal point link to 2V.

(It should be 10K at R2 but I couldn’t get the bourn pot to set it to 1.999 Volts.)
China seems to have a lot of 200V versions, suspect they could be modified the same way.


I have 2 boards and 2 modified Voltmeters if anyone in the UK wants to have ago.



(I also changed the 5V voltage regulator (MIC39100-5.0WS) because the one specified seems to be either discontinued or a very long wait, C10 becomes a 1microF Tant and C5 a 220microF electrolytic with a > 100mOhm ESR for stability reasons for this chip)

Anyone know where I can get a better pump from? Dam things keep failing....
preferably a real good one if available.
The one I have is exactly the same as in the photo.

I have acquired a pair of Meridian M2 active loudspeakers and both a 101 and a 101B preamp.

I'm completely new to the world of electronics DIY.

Back in the day I lusted after this setup - it was well regarded, but the design simplicity did it for me. In a world of shiny silver Japanese kit the style of the Meridian kit was a fabulous counterpoint.

I am going to replace the electrolytic capacitors in the amps and speakers as a matter of course.

I'm also going to 'upgrade' the opamps. I know this is something of a contentious issue but I want to have a play. I'm going to fit DIL sockets to the boards so opamp replacement becomes simply plug'n'play.

Are there any other worthwhile mods to either the 101s or the M2s that I can consider?

With regard to the 101s I have seen mention of mods to rectifier circuits but don't have any details.

I'm keen to learn and quite excited to learn some new knowledge and skills.

I am intending to completely refurbish the M2s - re-veneer the cabinets and get them looking as good as I can. The drive units appear to be in great condition.

Any advice/pointers/details gratefully received.

Dear all,

This is a cross-post from the TPA support forum but I haven't received any answer to my question for 4 months now so I was hoping to find some help here.

About 6 months ago I purchased the TPA Rpi Hat and Cronus module.
I have installed Volumio on the Pi and I tried to install Miero's software for the Hat but the installation fails.

At it gave the following outcome:

root@volumio:/home/volumio/tpa-hermes-rpi-dev# git pull
Already up-to-date.
root@volumio:/home/volumio/tpa-hermes-rpi-dev# make clean
make -C /lib/modules/uname -r/build M=$PWD clean
make[1]: *** /lib/modules/4.19.118-v7+/build: No such file or directory. Stop.
Makefile:27: recipe for target ‘clean’ failed
make: *** [clean] Error 2
root@volumio:/home/volumio/tpa-hermes-rpi-dev#

We have also tried the installation with the Cronus installed and powered. Would this be required at all for the installation to succeed?

Anny suggestions or knowledge here?

Thank you!

Jordo

Hi,
I'll be building a sub for a car. i'd like to use two 10" drivers; each in separate compartment [20liter net volume; closed enclosure] (or maybe one 40liter for both- not decided yet). subs will be wired as parallel and are intended to work in 20-60Hz range (f3 close to 27Hz with a bit of eq).


i was thinking about using SB Acoustics SW26DBAC76-8 or SW26DBAC76-3-DV (voice coils in series). but i can find any measurements / reviews for those units;



can any body share some thoughts about those drivers? maybe any kind of measurements?


i'll be grateful 🙂

Please delete - Just noticed the Active Basstrap Post.

It's one piece in a set of three from an early Precision Power car amplifier. This one has 2 sockets, The next one has 4 sockets and lastly the largest one has 5 sockets. I'm guessing the pins would be about 5mm in diameter and the wire input size is up to 6ga or 8ga I'm guessing.
I'm ultimately looking for a part number if possible.
Thanks for looking!

For sale pair Toshiba 2SK117GR in matched pairs matched to 0.01-0.015mA) price is 4eur/pair.



Two of them equals to one 2SK170BL with slight higher amplificaton, even lower capacistance and also with lower resistance (desirable feature for R2R dac output) they are They are 100% genue(dealing with Toshiba for 10 years) most of the them are in 4.3mA to 5.8mA range. If you want extreme ranges they are also available( lowest 3.12mA, highest 6.21mA).

matched quads is also possible, 8of them makes nice Patrick's SEN for r2r DAC I have tried SEN CEN with sj74/sk170 and SEN sk170 x4 but 8x sk117GR sounds nicer- better bass and dynamics.

I have 2kohm Vishay RNCY90 to go with those as well.

Hello,
my search for the next amp-projekt ist still not finish. So i have to check the sources for some items. I look for some Eimac 327A Did anybody know a source oder sell some?

Thanks
greedings from Germany


Ps: to sell?...write a PM

I'm working on a pair of MC30s and one has got some problems.
It runs hot and distorted.
The voltage at the rectifier (pin 2) starts appropriately and then swiftly drops to under 300vdc. At start up, sometimes there is a fad in/out hum like a power tube imbalance that goes away.
Same story with voltage at the power tubes.
Filament voltage at the rectifier is 5.2vac, 6.6vac at the power tubes.
One issue is that pin 5 on the power tubes is measuring +2vdc, and the manual states that it should be -42vdc.
Any direction would be much appreciated.

The picture shows a JBL 2446. It shows where one attaches a horn. The exit hole in the center of the driver is about 2 inches deep and 2 inches in diameter. Is that hole part of the throat chamber or does it count towards the first 2 inches of length for whatever horn you attach it to?

Hi!

I'm doing a project where I have connected a microphone and an amplifier. It was very noisy before, as can be seen in one of the attached images, but now I have applied low pass filters.

Right now the frequency spectrum looks like the second image (with less noise) but I do not why there still is a peak at around 9kHz?

I've tried to filter both before and after the amplifer, but the noise is always there and with almost the same amplitude.

Can you brainstorm with me, could it be due to bad connection somewhere, bad grounding, wires, computer?

So I was presented with this little amp with customer saying there is no sound. The obvious fault is that the output transformer which carries the signal from the power tubes to the speaker is missing.
I need to find a 30W push pull 4 and 8 ohm speaker output.
I would appreciate if anyone could point me in the direction of said transformer.
As to why it's missing, well that's another story.

Cheers,
Rhea

Hi guys, I am looking for a very low leakage capacitor. Value flexible, say between 1uF and 10uF, voltage rating >10V. It should have a leakage less than 10nA at DC.
Does such a beast exist? Probably film, teflon?

Jan

I wonder if anyone can help diagnose this.

I have an intermittent crackling noise on one channel. It's in the power amp stage as it happens even with the preamp disconnected. It's not in the speakers or speaker cables as it stays on same channel when speakers are swapped.

The music still comes through at the same volume as the other channel.

The crackling occurs even when the input is grounded but is a bit louder when input is floating. There is also a slight hiss when input is floating but not when grounded. (The other channel never has this hiss).

I have looked carefully for any cracked solder joint and have tried tapping each of the components to see if I can make the crackle come on demand, but it seems to be independent of any tapping.

I have looked for any dirt shorting across tracks the circuit board.

It's not in the "power envelope"� circuitry as it still happens when this is disabled by removing the fuses on the +/-71V supply.

It's not in the speaker selection switch as I have tried connecting a speaker to the output track before this switch.

Any ideas for more tests I could try?
I attach a schematic.

Can anyone help with a circuit of this transport, sounds really good standard, it's got, unashamidly written across the front, Ultra-Low-Jitter-Clock-Circuit, I would love to try to make it better I hear they don't exist anymore, hope someone can help with the circuit.

Cheers George

I I recently bought a couple amps DIY kits from eBay and I need help with a schematics if you can help please thank you

I have a pair of 15" Pyle PPA 15s from a previous OB project that I'm having a hard time moving on.

Was wondering if I can actually integrate them as an OB sub alongside my current Pensils. I'm keen to keep the smallest footprint possible, and wondered if a SLOB might work, with drivers mounted face to face.

Can anyone advise the relevant t/s or other considerations for this type of design?

Basic parameters attached.

This circuit uses a trasistor instead of a front-end op amp.

So, I think we're often taught to have the highest inertia possible, with high mass platters, and weight concentrated around the perimeter.

But does this make sense with DC motors that have optical encoders that send corrections to the motors?

Examples would be the Linn Radikal, Mober and the Teres motors.

Wouldn't the inertia, make it more difficult for the motor to make a correction?

Would love peoples thoughts here and maybe an explanation of why the math wouldn't work out that way (if you applied a small change in force in an effort to correct the RPM variation)

Hello all,

Not sure if this is the right place, but. I have a question for you.
A friend of mine wants to install a subwoofer in a corner in to his living room; and knowing I'm "into such things" asked for my help in solving an issue.
His problem is that the hifi gears and loudspeakers are installed along a wall, while he would like to install the subwoofer on the opposite side of the living room, in a place 6-7 meters away from the amplifier.
His idea is to build a low pass active filter, connected to the amplifier outputs, and then route the filter output to a subwoofer amplifier; this is not a problem, both of us are quiet experts in electronics.
The problem is that there's no way to run a cable from the hifi gears to the subwoofer.
So, the only solution that came to our mind is to use some sort of audio radio transmitter/receiver.
So, do you know of any of such thing?
I can find a lot of TV audio repeaters, wireless headphones, and so on: but do you know a nice real solution, with (almost) zero delay, maybe an analog one, with a wide passband, that could transmit and reproduce the subwoofer low frequencies?
With h such a device, we could be able to install a subwoofer with an integrated amplifier, and only have to connect it to the radio receiver.
Thank you in advance.
Ciao,
Giovanni

I picked up this unit a number of months ago for pennies. As you can see in the pix it has a a negative and a positive 5v 10 amp, 15v 10amp, and 25v 3amp unites.

I have not messed with solid state but thought i might if I could use these.

Hello,

If someone has a spare set cedarburg daughtercards for the M2x I´d be highly interested.
Should be shipped from within Europe,

tnx,
stefan

Hi,

I'm looking at various solid state phono preamop designs out there, trying to learn from them and coming up with my own design at some point. (I know, there are a lot of working designs out there but for this one I want to have something that I understand from the ground up)

I'm still in the very early stages thinking about the general features and structure of the amp before going into designing the details.

One thing I know I want to build is the ability for the amp to be adapted to a wide range of MM and MC cartridges because I like to experiment with those a lot (I don't like step-up transformers).

So the overall gain needs to be adaptable and I have seen a number of approaches how that is implemented:
- Simple have one gain stage that can provide 40-65 dB by variying the amount of NFB on the OpAmp
- Use two stages (one before and one after RIAA) and make the gain in the second stage variable so it can provide additional boost in case of the MC cardridge
- Have a Pre-Pre-Amp stage that gets inserted before the main MM/RIAA stage to provide around 20-25 dB of Gain

I have a bit of a hard time figuring out the advantages and disadvantages of the various topology choices, so maybe some here would be able to share some wisdom on the matter.

What I like about the idea of the Pre-Pre-Amp topology is that that stage can be much more customized toward the needs of the lower impedance MC system, beyond simply changing the terminating resistor to load the cartridge apropriatly... may discrete transistors would make more sense in that stage than an op-amp

However, there are probably many more things to consider.

Cheers,
Lars

hi all,
i have been using a 24eur Meizu Hifi DAC (non pro version) for a while and it works great when plugged to my phone or my laptop.

being so cheap and small, i thought it would be perfect to use with a raspberry pi-Moode as streamer to feed an amplifier or headphones so gave it a try.

the good news is that it gives 2 volts and is perfect to feed my amplifier.

the bad news is that from time to time it makes hiccups and this is a no go... (much worse with a zero w but still noticeable with a 4b)

i really want to make it work because other than that it sounds excellent and the price and size i find it much better than a regular dac hat

does anyone have experience with this particular dongle on a pi? any suggestion to make it work without hiccups?

thanks a lot

Simple question, should all the standoffs be electrically connected to the case or just one standoff and put the earth ground at that location. I'm thinking the last.

The picture shows a modified single rail power supply board with all four standoffs connected to the ground of the power supply and through the standoffs, to the case.

I'm thinking I should cut the traces to three of the standoffs and just leave the upper right one connected to the supply ground and connect my earth there also.

View attachment 995775

Hi,

The schiit modi is US$99 without shipping. That puts it in the same category as many ebay board DACs out there. And this already includes a nice case...

Has anybody though about buying one just to mod?

Schiit Audio Modi review - $99 killer | Digital Audio Review by John Darko

It already has a CM6631 USB chip, a AKM4396 DAC and a AD8616 output chip.

If you have modded one, share your experience modding the DAC, (better caps, Direct out etc).

I am thinking about using a simple pass B1 pre amp for the output stage with a low pass filter. And I guess giving it an external 5V power supply

Any thoughts on that?

Thanks...

Oon