I'm focused on speaker design and construction and I'm here to learn from you experts! I've built several pairs but want to simulate on my PC to end up with a better XO. My current project is replacing the woofers in a pair of Infinity RS2000s and re-doing the XO. I found a helpful video as a good starting point and just purchased a pair of Dayton Audio RS180-4 woofers. 4 ohm with what looks like a good match with the RS2k cabinets (from what I can glean of Vance Dickason's book). I'd appreciate any feedback - especially if someone has already been down this road. Thanks, John

$170 shipped USA​

I also have the JBL 2425J drivers themselves, many of them, and horns.

2 of the drivers need these diagraphs.

Complete working amp, toroidal 600va trafo
Someone interested? 800 euro
Nelson Pass sorted Vfet’s closely matched, 4x2sk82, 4x2sj28, I build too many amps…

Hi,
I have got a Chinese PCB board and its called a super regulator by Jung, not sure if it is one of W.Jung's designs but it works quite well, I tried it with a NOS DAC chip, not a but result but it sounds very forceful, a bit too much of a good thing I would say.
I have drawn the schematics of it and it would be great if the design can be improved if can to be improved obviously 🙂.
...please have a look at it and add your comments.
best regards
K

I picked up a Zapco AG150 that someone else started working on. When testing it on a 2.2A current limiting supply it will try to draw the full 2.2A but in pulses. I removed the rectifiers and it only draws .25A with no pulses. The power supply transistors have a sine wave input and output. All of the output and power supply transistors have been replaced and I am not confident that they are correct as I had another amp from the same person with the incorrect fets installed. A schematic or part identification would be great. Any thoughts on the repair would be great also.

Have three of these white spacers not sure where they are meant to be located , dismantled the player and then worked on another project and forgot where they should be positioned.

hello. im a long time user, donovas being my old handle, and this is my second account I'm making for the purpose of promoting via social media my audio brand that is in the works. The brand is called Sonocus, sound tree in latin, and the goal of our products are to offer the highest quality circuit design at any price point in a packaging that is highly affordable. In other words, another giant killer hopeful.

I'm comfortable with the outlook of the project though. I have been working on this single design for 3 years and it was already received favorably in Seoul where the sales were my partial income.

the project is a dual mono preamp, now modified into a headphone amp that I'd like to post on kickstarter very soon.

Anyways, thanks for letting me ramble and hello.

mods: could you please change my name to SonocusEric if possible? thank you

2 x Precision EF3-3 boards (V 4.2) which includes 2 x wolverine IPS boards. (Color -Black, )
$40.00 USD.
EF3-3 IPS, Pre-Driver & Driver: $20 USD (6 Heatsinks Total)
Total 60 USD , + shipping (worldwide). Paypal for friends

Hey there DIY-Audio-community

I’m a total beginner when it comes to Hifi-Projects but since my current setup is in desperate needs of some upgrades and I’m traditionally on the DIY-approach when it comes to “new” things, I thought about constructing my own speakers… how hard can it be? During my research with a lot of detours, the World Wide Web finally lead me to Charlie’s infamous jazzman design and I’m in quite in awe about the community surrounding the project, that is mainly based on this board. So into the rabbit-hole I went…

In a first instance, I was simply impressed by the aesthetics of this ESL, which is why I got completely lost in the project. After a first attempt to simply copy the design and therefor understand the design-choices made, I had a bit of an idea while researching for appropriate wires...

Since this is a one of a kind and my workshop is quite limited in size, I want to avoid the tensioning-jig that is usually necessary for the elongation of the single-stranded wire, by tensioning the wires within the actual Speaker.

So, in short this is the attempt to have a segmented wire-ESL with tensioned stranded wires.

By putting tension on the wires, one could also avoid a lot of the horizontal segmentation. The wire tensioning would be achieved by simple harp-pegs, that are screwed in the top of the speaker. This of course results in an odd number of wires per electrical segment. In my case 5 instead of 6 in the Jazzman-design, so my active diaphragm width is actually a bit smaller than the Jazzman-design. Nevertheless, I hope to be able to copy as much as possible from the original design, especially when it comes to electronics… Really not my expertise yet 🙁

This will be a hybrid design with open-baffle speakers. I do have four Peerless SLS 8 (830667) left, which I hope to be able to use. One idea is to use two dual speakers per speaker, the other idea is to integrate 1 per speaker and build a sub out of the remaining two. But I haven’t checked if the spl would be sufficient for an open-baffle design. Since this is really in the early stages of research, feedback is very welcome!

I’m probably in way over my head with this as a first project but maaaaaaaybe there is a chance for me to actually get these things running 🙂 And even if this is a dead end, it was quite a fun journey so far.

I have some drawings of the project attached.



Where I am at the moment:

I started a first prototype based on some leftover 22mm wood, some FLRY-A 0,5mm2, 1,55mm OD cables and some harp pegs. I build a quick router jig and milled one vertical segment. constant wire distance as well as looping of the cables is achieved by some 3D-printed parts.











After having tensioned a first loop, things look promising, after 3 days under tension the wires are still as straight as they can be. I had some problems with the wire snapping at the top in the beginning, which is in my opinion mainly due to friction in the 3D-printed parts and the loops around the nails. I’ll have to redesign this part in order to allow the wire to distribute its tension over the whole length. But I’m optimistic that I’ll achieve this in the next try.

Some recent measurements, show me a 2-3 triodes phase inverter with less than 0.0x% distortion, with more than 50Vrms on both outputs, with no feedback 🙂

Partially built ACA Mini includes the heatsinks.
Requires the transistors and few other parts.

£30 plus shipping

I have one last pair of PCBs (shown in Photo) for the construction of a Moving Coil RIAA preamplifier as was presented in my article for Audioxpress (March 2014).
The price for both PCBs (two PCBs are needed for a stereo preamplifier) is 55 Euros plus shipping.
If you are interested, send me an e-mail at gntanavaras@gmail.com

Hi all! not really a new member but never posted an introduction! I’m nicoló, i love building audio stuff and do some repairs whenever I can just for fun!
Cheers all!

Hello, I have an old 80s model jvc amplifier/ receiver and the only outputs it has on it are group one and two speaker wire outputs. The issue is, i just fixed an old klipsch subwoofer that i found on marketplace and the only input it has is RCA or Sub in. How do i go about connecting these two items together? Would connecting wire that has up to 60w running through it to an RCA input on a sub be harmful or would it even do anything?

Hello everyone.

I've been lurking on these forums for years. Currently in the process of designing no-compromise studio monitor system. It will be a 4-way looking something like this:

20-60Hz - 15" woofer (still deciding on the woofer)
60-600Hz TAD TL-1601b
600Hz - 8,000Hz TAD TD-4001
8,000Hz and up - RAAL ribbon

Looking for the best horn to make the most of the TD-4001 in those frequency ranges. Was recommended the Yuichi A-290, and can also get the TH-4001 clones made. Looking for the most transparent setup, and it will be driven with a high quality Linea Research DSP (gasp) and Benchmark / Bryston amps, so we have a lot of tools at our disposal, such as time alignment, FIR, linear phase EQ, etc.

Are there any other horn designs we should be looking at for this? Anything we may have overlooked?

Your help is much appreciated.

Hola. Soy nuevo en la comunidad y estoy muy contento de tener la oportunidad de estar aquí. Mi principal interés es la electrónica de potencia y el audio en general. Gracias.

Проект RM-6.
Начало

I want to simulate the circuit of a TAA621 IC in LTSpice.
However, there's a transistor with two collectors (T10, see datasheet linked below).
Any suggestions on how to substitute it?

TAA621 Datasheet: https://ve6aqo.com/Datasheets/German/TAA621_DATASHEET.pdf

I have owned a set of 2CeSignatures for several years; six months ago I purchased a Vandersteen Model 2W subwoofer on eBay. (Presumably, these two components should work well together.) There were no crossovers devices with the shipment (my mistake). A high-pass filter must be injected between the signal source (preamp) and the amplifier. The specifications of that filter are subject to a set of variables including the input impedance of the amplifier. At sale, Van supplied an adjustable crossover component (W-X2) that could be used to ear-test and determine the correct crossover device; once determined, the user could purchase a set of permanent filters form a Van distributor; and the W-X2 would no longer be necessary.

Lacking the W-2X, and using an online filter calculator, I built a few simple. cap/resistor filters using 50Hz cut-off, and random capacitance and resistance values (C/R values were set based on what I had sitting around; notice no input impedance is contained in that calculation.) Nothing worked, so I gave up and bought a W-X2 from a long time Van dealer ($140). Following instructions, I set the only adjustable (dip switch) value which was to be one level below the amp impedance; in my case, with a 50K Hz amp, the next lower value was 33Hz. Works fine, sounds good.

Assuming that 33Hz stays as the most pleasing level, I will have to find a dealer that carries a set of 30-40 year old filters marked "33." Why don't I just keep using the W-X2 and forget finding permanent filters? Per a short conversation with Richard Vandersteen, he told me to be sure to get permanent high-pass filters because the components in the W-X2 were crap and sounded like it. But, what would he know?

Anyway, this is a long lead up to this question: could anyone provide a schematic so I could build my own high-pass filters?

This driver has weak bass and treble, but the vocal extension is excellent.
It would be difficult to achieve this kind of vocal reproduction with a multi-way speaker using a network or a filtered full-range speaker.

Internal wiring was supplied with the speakers, 6mm MDF and PVC sheets were made by Daiso.
Material cost is less than 1000 yen (6.5 USD) per pair.





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I have an HDMI ProII Transport, and a reclock Pi, if anyone is interested. The HDMI Pro was sent by mistake, and Ian said I can keep it if I paid for shipping for the correct part...I don't need the HDMI Pro. It basically hasn't been out of the package except by accident, until I realized it was the wrong part!

I've been asking questions about tubes and capacitors and performance, where the answer always seems to involve "Does it meet specifications?". So, I figured I'd better check.

Tests were performed with a Scarlett Solo into a Mac Mini running Room EQ Wizard. Input voltage for all tests was ~1.76V

The high-frequency rolloff appears to be in the interface, as it appears in loopback measurements.

Frequency response
Manual States: +/- 0.25dB, 5Hz-30kHz
Result: 0.23dB total deviation, maximum to minimum (excluding high-frequency rolloff)

Distortion
Manual States: Less than 0.01% at 2V RMS output, 20Hz to 20kHz
Result: 0.007% THD maximum between 20Hz to 20kHz

Intermodulation Distortion
Manual States: Less than 0.002% at 2V RMS output
Result: 0.02% at 2V RMS output*
Note: Measurement was obtained using 7kHz and 13kHz twin-tone
--

I've included slides for the frequency and 2V distortion measurements. I've also included a 5v output static distortion slide for interest, although it is not relevant to any of the measurements discussed.

Thoughts: The frequency and distortion numbers seem to be inline with specifications. The IMD is high, but I don't understand the potential causes or ramifications of this enough to discuss it. For all measurements, I consider both my tools and techniques suspect, although I am making ever effort to be accurate, with the equipment I have. I allowed the amp to warm up for approximately 15 minutes before taking these measurements.

For full specifications: https://www.arcdb.ws/model/SP8

*Note: Slide for this measurement was lost

I have been reading here, there, and everywhere about the different Pass amps that have been made. I have many questions which is evidenced by my random scatter-brained post. MY question for this thread concerns the possibilty of substituting the Semisouth power J-Fet's in the Aleph J layout. THis uninformed question is based on the firstwatt articles including specifically the Sweet Spot. I am a newb, but have plenty of time to ask questions while simultaneously trying to figure out what the hell i am talking about. If this is doable, i will probably go ahead and buy the pcb's from Peter if they are still available. MY thinking is that this amp would be similar to the J2. I would just do the F5, which is a much easier build according to most, but i have limited funds and think, at least for now, this is what i want.

I know several V-FET / SIT data sheets have been posted over the years across many different threads, but I thought it'd be nice to have them all in one place.

Here's one fresh off the scanner - more to come when I have time to spare. Meanwhile, feel free to attach or link to whatever you have.

(Note to Mods: I hope posting these doesn't violate rule #9 - please delete the thread if you think otherwise. Thanks!)

Edit: I realize my file naming convention is not immediately obvious ==> the attached PDF contains 2SJ18, 2SK60, 2SK63 and 2SK79.

I haven't made a decision as of this time but I am planning on replacing my JBL 2380A horns with clones of either the Yuichi A-290 or TH-4001. The drivers in use are Radian Neo 950 FB / 16. (Recent upgrade from JBL2440)

Athos for either A-290 or TH-4001:

AthosAudio - Passionate about wood and sound

They also sell on eBay and have a good buyers rating. Located in Hungary shipping is a bit pricey, but manageable.

MAKA for Yuichi A-290:

Homepage - MAKA Precision Horns

Located in Holland, likely a bit quicker and a little less expensive to ship.

I've heard of both, have no direct experience with either.

I'm currently trying my hand at a USSA5 amplifier and need a few more exotic capacitors. Does anyone have at least four of each of these in his drawer and want some space for new parts and some cash?
What I'm looking for:
2200uF 16v United Chemicon Polymer APSG160ELL222MJ or RNL1C222MDS1 and
4700UF 35V United Chemicon EGPD350ELL472MK30H or EKYB350ELL472MM or UKW1V472MHD
-min. four pieces each

And yes, I know that some of these types are still available from some retailers, but ordering a handful of components from them always involves astronomical shipping costs—so I'm asking you first.

Thanks for checking!

I read about this a long time ago. Development in amplification didn't jump from vacuum tube then to the transistor, there was something in the middle......the magnetic amplifier.

WWII Germany perfected the device, and I read that one of their V-2 rockets crashed in England and didn't explode. When it was salvaged and analyzed the scientists there pieced together a magnetic amplifier used in its construction.

I have a couple of books on them, and I heard that it could be used to amplify sound. I did a quick search before making this thread and the subject is a little dead.

Just today I found this awesome site:
Homemade Magnetic Audio Amplifier.

http://sparkbangbuzz.com/mag-amp/mag-amp.htm

This is a tantalizing bit from the first site I listed site:
"The mag amp is true amplification without the use of tubes, transistors or IC's but it does require the use of an AC power source. While most ac oscillators require the use of transistors, this amp could conceivably run using an AC power signal from a carbon arc or maybe even a zinc oscillator or similar."

I wonder if the experts here could build on this and make something really well performing.

I hope somebody is interested in this stuff as much as I am, it looks neat.

Designing my amps around TPA3118 since the beginning I am always curious to discover these in commercial applications. This one was inside the Bose Soundlink. It can be seen that the bean-counters replaced output inductors by ferrite beads here. Considering the short speaker cables and the metal housing this might comply with EMC regulations anyway.

I'm trying to increase my knowledge of bootstrapping techniques and started experimenting with a simple bootstrapped op amp. It's all done in LTSpice so far. I can get it to work just fine, however... It's extremely finicky on component values. The schematic below works fine, but if I change R3 and R7 from 15k to 12k, the whole thing latches up. I'm suspecting this has to do with SPICE. Maybe it's having trouble finding the OP with all the loops in the circuit?



Here's the performance with 15k resistors. Output in the middle and high and opamp VCC and VEE at top and bottom. Looks great!
Now I nudge the values of R3 and R7 to 12k. As you can see, it latches almost immediately. Is this a legit design problem or SPICE weirdness? BTW, increasing the resistors to 18k has the same effect. I tried replacing them with zeners and voltage sources, but to no avail.

This is going to be the topic where i post Gerber's that you can order yourself. Just don't sell the boards please, allthrough there is nothing i can do to stop you from doing so.

Suggested board house is JLCPCB, those are the cheapest.

Most of what i post here are boards for tube projects. I will try to add some description of what exactly it is.

The fastons i use are 61-1536-11/0031 OSTERRATH. TME.eu symbol: FS1536/NC

However i do not offer warranty on my designs, so order at your own risk.


furthermore all through i have a lot of spare time please i'm no tech support.
If you see something that suits your needs but isn't quite to your taste, pm and i will make changes for a small fee.



If you want to send me something for my efforts, my paypal is on some of the boards.

Here's the first revision of the mini-build guide for installing Zen Mod's Soft Heat circuit for the Korg NuTube B1 preamp. Feel free to post pictures of the modified board here to help others understand how to go about doing it.

Here's Mouser cart link for folks who want to buy the parts themselves.

Note that NO Trace Cutting is required with this approach. Removing the 270 ohm resistor is the "cut" and allows one to revert back to the original design w/o the soft heat circuit easily if one so desired.

A pair of original ESL63 stands. They have been in storage and are not pretty, paint has come off in places.
In 's new' shape they go for up to 300 euro in some places.
If you know what a sand paper is and know how to handle a spray paint can, you can pick these up at my place for 100 euro.
Pick up only, so attractive if you are in southern Netherlands, Belgium or adjacent German area: Aachen/Maastricht/Tongeren.
Let me know.

Jan

I went to AXPONA in Chicago this past week, where I could hear tons of systems, compare and enjoy the best of them, critique them, and not get impressed in some rooms. I found some DIY speakers that were my favorites and searching for them led me here. Cheers!

Hi All,
in the following I would like to describe my way to my first ob construction (and at the same time my first own speaker construction ever). After building two boxes I became aware of a thread here - the Manzanita. I built it and it happened - the OB bug bit me, it is a great speaker!



After that - it always has to be bigger - I also built the Manzanita Ultra.
But we didn't become friends, this speaker didn't fit my space, my music, my listening habits, etc.



In particular I like the open way of playing, the room, the stage, I haven't heard anything like that from conventional speakers, up to the high four-digit price range... I still tried to listen to music with conventional speakers, but something was missing... That was the point where I decided to make my own OB construction. And if possible, it must have a high sensitivity in order to be able to operate it with enough reserve with First Watt amps without any problems.
So, enough of the introduction...

Right from the start it was clear to me that it had to be a woofer-full-range combination, i.e. a 2-way system (the xo is easy there... I thought). At the same time I found a thread about the new SB Acoustics SB20FRPC30-8. Cheap enough so I ordered it straight away and two days later I installed them - in a TL box that was absolutely not designed for this speaker. I just wanted to know how the speaker sounds, approximately. And what I heard made me happy, to put it briefly.



The next step was to install it in an OB - I used that of the Manzanita Ultra. But since the Manzanita´s woofer is not very sensitive (at least compared to the SB FR with 92 dB), a new woofer was needed. Based on a recommendation, the choice fell on the SB Audience 12" OB, which is intended for OB applications. "Quickly" built an xo - low pass, high pass, 6 dB/octave, done... and it sounded terrible
There was a lack of... everything. And the measurement confirmed it...





To improve the highs I added a tweeter, of course the xo had to be redesigned quite a bit.
At first it sounded good (in the upper range), but the longer I listened, the more unbearable it became...



The lack of bass was also very clear... so I figured a second, larger woofer might help (yes, it can, but not in the way I thought).
After a short search, the Eminence Alpha 15A was delivered - and that's when things really got going. I guess I've built countless baffles out of cardboard and if it sounds bearable, also out of foam... with and without wings, with big and small ones, or even with asymmetrical wings, but it didn't really work out. After a while the bass was okay - far from good, but okay. But there were big problems in the xo, because I treated the 15" and the 12" woofer separately, with different (high) crossing frequencies. And the mids... absolute no go...
There are no pictures from this phase, that was more doggedness than conscious action 😀 Of course I also changed the xo every time... I didn't even get to measure it because I usually didn't like what I heard.

That was the point where I thought "what were you thinking, or even imagining?" But I didn't want to give up.
So - read, read, read was the motto. And most importantly, understand what works and what not. And why. @Pano helped me a lot with his contribution - many thanks

The most important thing was to lower the crossing frequency. Originally I crossed at about 1 kHz - that's incredibly high, even if that seems to be okay according to the specification of the drivers. But it is not. And that was one of the keys. First I decided to switch the two woofers in parallel (gain in output) and then I lowered the crossing frequency to around 120 Hz - and it was like a revelation. There was also the almost endless trial and error with and without wings, different wing shapes, heights, depths, etc... until a certain size and shape proved to be right (better: to be the best for this configuration).

But the revelation was only partial..., the mids didn't want to appear.
I stared at the circuitry of the xo in the SIM - and then inverted the full range. Wow, the fr response became "smooth as glass".
Put into practice quickly.
With two different full range drivers.
The MarkAudio Alpair 12P was added to the SB as an alternative, because I didn't really like the high-frequency range of the SB (on paper). So it started with the full range again. Cardboard baffle with different positions; middle, right, left... I'm still not sure which is the better option, but these are minor things compared to the start...



Currently the 12P is in break-in, the SB is now centrally positioned, and I like it.
And now the speakers sound incredibly good. For real. The best of all wives (she has nothing, zero, niente, nada to do with this hobby or with music) has heard all my speakers so far and yesterday also the "new ones"... and she said - "wow, they are them best of all, but far the best".
The feeling of pride came on 🙂



I took measurements today - I like the fr response 🙂



And finished a version of the baffles with the router. They are made of 18 mm MDF, in this version with decentralized placement for the Alpair 12P.



Yes, three-piece baffle. One of the findings was that - if the gap is not larger than 4-5 mm - the sound is better (for me).
I have no idea why, maybe the resonances of the individual baffles don't influence the other drivers.

Well, of course it's not finished yet. But I'm incredibly happy. I started at the beginning of November and there were phases where things looked bad.
At the end of this contribution, the current status of the xo - not quite finished yet (as you can see, not only the SB and the 12P are taken into account, but also the Sonido SWR250, which I will be ordering shortly).
This is so much fun.




The journey will continue 🙂

Audio Amplifier Performance Assessment Program (AAPAP)

(This introduction must be read in conjunction with the accompanying Excel spreadsheet)

General use and objective of AAPAP

The program looks at several important amplifier performance areas and provides an objective method of assessing the design and engineering effort brought to bear in reducing or eliminating shortcomings that will materially affect electrical performance and therefore sound quality negatively. The philosophy behind this approach is that, for example, hum and noise or TIM/SID cannot bring positive benefits to any amplifier either electrically, or when assessed separately, for sound quality. These are problems that require design effort to eliminate, and this is what AAPAP addresses.

The assessment process can be used during the design phase to guide the designer towards improved electrical performance and/or to assess finished designs, be they DIY or commercial.

For assessment and scoring, the amplifier under test (AUT) is treated as a black box except for the protection features scoring where the AUT specification is consulted.

The following areas of electrical performance are covered by AAPAP:-

• Output Power
• Capacitive load drive capability
• Overdrive recovery
• Frequency response into 8 Ohms resistive load and complex load
• Complex load drive capability vs distortion at high power levels
• THD + N at 1 watt into 8 Ohms (0 dBV) and at rated power (dBr measurement)
• IMD 19+20 kHz at 80% of rated power into 8 Ohms
• Noise floor of mains-related noise and hum, including cross-channel ground loop noise
• Speaker and amplifier protection assessment
• $ Cost per stereo watt (not scored, but must be stated in the assessment)

The assessment program explicitly does not address subjective notions of amplifier quality, only those that can objectively assessed using test instrumentation.

The tool distinguishes between different amplifier technologies and assesses performance within the capabilities of the designer's chosen technology. The technologies currently covered are: -

• Linear solid-state amplifiers with global feedback
• Linear solid-state amplifiers without global feedback
• Vacuum tube amplifiers
• Class D amplifiers will be added to the program once agreement is reached on how certain parameters will be scored

Tool outputs

A report card and audio analyser plots against which the parameters listed above are scored with a top-level score that places the amplifier in one of 6 categories as detailed in the Excel spreadsheet attached below.

I have already searched for info on this site and found a very informative thread from a PDX V9 owner but it falls short of explaining now to remove and replace ribbon cable. Recently purchased a used PDX F4 and one channel is not working properly. I suspect it is the preamp ribbon cable but I have not worked on one of these before and I am afraid to force the 15 year old plastic connectors. I have attached pics of the bad channel and a good one on my scope and the connector I am looking for help with. I don’t know how to release the ribbon cable connectors.

This is the Soft as a Feather Pillow Plus (SFPP) circuit that combines the solid state relay SFP soft start with a solid state relay low voltage switch remote on/off capability. There is also provision for remote shutdown logic via closing a contact that’s useful for thermal switches, etc. The SFPP has about a 2 second long soft start period where the in rush current is reduced by going through two NTC resistors in series. After 2 seconds, the NTC’s are bypassed allowing full current to go to the power transformer.

The circuit can handle up to two loads useful for dual trafo monoblocks in the same chassis.



Example of usage in single chassis dual monoblock amp:


Schematic:


Here is a video demonstrating the operation.
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The board has some tricky SMT parts with small pin spacing to solder. I am getting a new version with simpler easy to solder SOIC8 parts in the future but still have not tested that board out yet.

First, I would like to give this one to find a space for discussion.
I first thought of here.
It is the same as the structure of many friends here.
Maybe I didn't do the best.
+ -75V DC

I have been used for a few days in a row, it sounds very good, from the test also and I expect the same.

Although it is still a little hot, I replaced many capacitance, testing,

I hope that any I design an amplifier can steadily work for many years.

In the case of more than 300 w power 4 ohms, can stable operation.

Temperature basically control within 50 degrees, but I think maybe a fan, will be cooler.

So I need to replace 2SC2878 in muting circuits. In the short term I got a couple of (hopefully) NOS at a high price. But I'm curious to know if any current parts have been determined to work well as a drop in replacement?

Thanks...

I'm looking at affordable option to replace the OEM Plate amp in my JBL E250P which is rated at 250W 4 ohms. This is part of my home-theater setup and the sub amp is actually driven by the signal level output from my Denon AVR.
A replacement plate amp (such as a Dayton Audio) is both expensive and physically prohibitive as involves much more rework of the cabinet to accommodate.

In mini amps, what I'm currently considering might be:

Aiyima A3001 - https://www.amazon.com/dp/B08LZFBLDM or

Nobsound G2PRO - https://www.amazon.com/Nobsound-Hi-Fi-Subwoofer-Channel-Amplifier/dp/B07TTMN51V

These look to be pretty much identical inside and utilize the TI 3255 - one difference being the power adapter is 6A for the Aiyima vs 5A for the Nobsound
I'm also wondering whether upgrading to a 48V 5A power adapter is worth the investment for either of these and give a meaningful boost in power?
The benefit of those is they are certainly easy to integrate, just hook up to the speaker.

Then there's this option to go with a Sure/Wondom board:

e.g. https://www.amazon.com/400Watt-Class-Audio-Amplifier-Board/dp/B07HHNWQSK?ref_=ast_sto_dp
Then get an appropriate power supply to drive it - lots of inexpensive options on Amazon.

I'm not sure that the mini amps are enough to drive that sub although I've seen reviews of others doing similar as plate amp replacements. For sure the power number they quote are wildly optimistic though, per dyno tests of similar on YouTube
I don't have any point of reference for the Board type solution but even if those specs are exaggerated, then would still be ahead of the minis. (they have 5 & 600 W boards too, but thinking this one would be adequate) Integration is not really much of an issue, I would just fit the board and PSU in the sub enclosure. And you can even get a volume control for under $10 for those boards. A low pass filter would not be necessary as handled by the main amp.
Board, power supply and volume control would collectively be about $85, very similar to the mini-amps, which would however be a little more if adding a 48V adapter.

So what are your thoughts/opinions?

I have a Pioneer SX-820 that has developed issues while on FM: low volume (about 10% of what it should be), one channel has less volume than the other and loudness switch does not work. Both The FM Stereo/mono switch and loudness switch have been cleaned thoroughly. On all other modes such as AUX, Phono and AM Radio there is no issue. Any suggestions where to look for the problem. Any technicians out there?

Hi,
I have a long history of dabbling with DIY speakers - I dived in with a KEF Concerto kit in 1975 at the tender age of 15, then after a long hiatus starting around 1990 I designed and built some Home Theater subwoofers (1 x sealed, 3 x ported and 3 x IB) and built a set of three DIY Sound Group "Elusive 1099" kit speakers.

I am now retired and just for the fun of it I have decided to have a crack at designing a pair of bookshelf speakers from scratch. I am about a week into it - the drivers have arrived and I have a basic cabinet design. The remaining bits and pieces are on are on the way so now it get's serious - the next step is to build the cabinets and take some measurements so that i can start a crossover design. So much to learn....
Cheers
Bill

I have several ultra-low distortion oscillators from Viktor. This one has both 1kHz and 5kHz oscillators.
It sports both single-ended and balanced outputs as per Viktors recommended connections.
Has internal SilentSwitcher so runs from 5V USB absolutely clean, I routinely got down to -150dB distortion in both frequencies and all outputs.
Yours for 150 euro + shipping at-cost.

Jan

ALL SOLD
I am advised to create a new sale post instead of riding on the old one, which I have sold a couple years back.
I have now additional boards for sale because I am beginning to have the I/V op amp stage on some of my DAC boards.
Sorry for the earlier confusion.
Working AD811 IV board, more details can be found here:
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-368#post-7451599
https://www.diyaudio.com/community/...including-burson-audio-op-amps-as-i-v.394295/

Board + shipping to you = Singapore Dollars 210 paypal FF only

Hi, Is anyone successfully connected

Bose PS321 II powered Acoustimass subwoofer with an external amplifier?​

If yes, can you please guide me. Thank you.​

Hi Everyone,
I based in Muscat, Interested in world of Audio. Used few setup as of now. Here I am to learn and gain knowledge about audio. I am sure this community will help to connect with other experts. Thank you

could someine olease help me understand how to use anything that i have got on hornsrep to use in akabak?

i can upload any details needed from hornsrep

Sell as a full lot or individually various values/type inductors with few hours of use. Price 60%of their new value+ shipping
Lot 1 Intertechnik 2x0,47mH, R0,11 2mm wire
Lot 2 Mundorf L 100 2x0,39mH, R0,29
Lot 3 Solen 2x0,56mH model 16.56
Lot 4 Jantzen 2x 0,33mH R0,22
Lot 5 Jantzen 2x0,47mH R0,25

See pictures

Dear members,

Please take a look at the attached very simple power supply ripple filter.

Key performance figures:
406 V offload voltage
134 mA quiescent current
14 mVpp ripple

These are comparable to a 15H choke (~100R Rdc), yet you can get all parts for the mosfet filter for less than 1€, compared to the price of a decent choke.

Am I missing something, or why are chokes still so popular in our tube amp power supplies?

Cheers

Bought from Radio Antigua and never used as that build project never materialized. Due to shipping costs prefer to sell them both together. Brimar is the black plates,Halo getter with smoked glass. Both I paid 130 Eur. See picture and make your offer. Ideally want to get back same money 130 Eur and will gift the shipping to Europe destibation(not cheap these days) but fair offer will be accepted

Sell new for 70 euro+ shipping. I propose 50 Eur delivered to Europe destination(subject to check from my side of shipping costs, provide destination please)

They have been soldered to a speaker to test freq response and then choose a different mH value

Sell 2 inductors as per object. Used for some time, so tin residual on ends foil. 3 months old. Bought new for 95 Eur, sell for 50eur +shipping.

Hi all you folks, i ask for your competence for the Hiraga amp "the monster" that seems to me to be a interesting and simple amp. As anyone of you ever builded it? I'm interested to study a mosfet version to use it as car amp to economize to PSU. Any comment is welcome.

I just came across this article and I have to say I have never heard of magnetic amplifiers before. Were these types of designs ever used in amplifiers or other high end audio we see today? Considering this was used for military tech at the same time as the vacuum tube I would think there would be some audio maps made this way.

Magnetic Amplifiers

Does anyone have schematics for this technology or ideas on if it's worth salvaging for home audio?

A question regarding Merlin's Active Smoothing chapter 4..

In Merlin's book Power Supplies for Valve Amplifier there is chapter 4.4 about Active Smoothing.
In that chapter there is section 4.4.1 The Capacitive Multiplier, and section 4.4.2 The Gyrator or Simulated Inductor.
To my untrained eye fig 4.29 (practical cap multiplier [CM]) and fig 4.35 (gyrator circuit) look quite similar (I not sure if it is permissible to post the schematics so I shan't).
So.......could a gyrator and a CM be combined into their one unit?
The only advantage may be a little space saving.......I dunno.
I think Gingertube posted a schematic similar to what I envisage.

https://www.diyaudio.com/community/threads/power-supply-mosfet-vs-choke-filter.261117/#post-4038197

Is it possible to do this and if so and both are combined is there anything to look out for?

tim

Hi all,

I know today we have streamers and smartphones but my audio desktop PC works very well for me and I'd like to stay with it. I've been using it with a wireless keyboard/mouse set for "remote control" and I was looking for a similar solution for the monitor. Some internet research returned "WIFI to VGA adapters". This one looks nice and inexpensive but now discontinued https://www.google.com/url?sa=t&sou...MQFnoECBUQAQ&usg=AOvVaw0IRrCCsbjutvk6eYdBacmu and the new model comes at a much higher price. I can find a few cheap devices but they mention iphone and miracast so I don't know if they are what I'm looking for. It has to work without an internet connection for this win7 PC. Low resolution is OK. Low cost is a requirement. Any suggestions are welcome.

I bought a Vivid V6 single opamp with my own money - definitely not a paid shill like many other Burson reviews I see!

I've measured its distortion performance using the QA403 audio analyzer and here are the graphs, first distortion v. level for both inverting (gain=-1) and non-inverting (gain=+1) topologies:


Clearly this opamp has decent (but not world class) distortion performance. Powered at +/-15V. 600 ohms load seems to be handled in its stride.
Alas the power consumption is a massive 13mA with no signal (the only pitiable specimen of a datasheet I could find claimed 8mA). That same datasheet only claimed 0.02% for distortion, which perversely under-sells it - perhaps the datasheet is not for the Vivid V6?

Little bit let down at higher levels, but most practical uses will be somewhere in the 0 to 10dBV range.

Frequency response:


No signs of performance dropping at HF.

19kHz/20kHz IMD:

Again decent performance in line with other graphs.

So the only elephant in the room is the cost - there are many opamps with similar or better performance that are much cheaper - for instance OPA1642 will do rather better with only 1.8mA per opamp...

The high power consumption makes it run at 50C or so which isn't great.

The packaging it came in was not anti-static which is worrying.

Why on earth don't Burson make a proper datasheet for each of their opamps - its not like they have anything to lose by stating its true performance which is much better than the existing terse effort: https://drive.google.com/open?id=1JyV88oA-33QHSHbGYF16A3FRW1mDRV1N

I guess my conclusions are:

1) If you have one, don't worry its pretty decent performance.
2) If you don't then think twice and look at cheaper and cooler-running alternatives like OPA1688, LM4562, OPA1656, ADA4625, OPA1612, OPA1642, OPA1652, OPA1662 and more... (NE553x if you can still get them!).
3) Its fussy about decoupling, you can't necessarily get away with just 100nF between V+ and V-, make sure both rails are decoupled to ground as well.

[ Oh one other thing, my unit came with the polarizing groove on the base and the case 180 degrees apart - turns out the case was correct and the base was wrong, but that's rather disconcerting... ]

I can't help myself buying a packet of cigarettes every now and then.
I think I am an addict. 🙂

I already own a pair of Capaciti E160 though I bought them recently and unsurprisingly found the membranes were in need of replacement (poor sensitivity and very uneven FR on one panel due to blown resistors). They were refurbished but not yet shipped back.

I now have the chance to buy a pair of ML Electromotion for less than what I paid for the Capacities + Refurb. They are still on their original foils which are 8 - 10 years old. I could drive there, listen and measure.

Supposing the panels are still good, for how long can I expect them to still live? Can I expect superior sound from the curved MLs with their 500 Hz XO to the woofer vs. the full range E160 (which will be joined by a sub below 70 Hz)?

Thanks

speaker dave has passed away. May his soul rest in peace.
Below is his message from his wife.

Dear WonderfulAudio and all --This is David's wife Melinda with sad news that David died mid January. He enjoyed the diyAudio forums immensely. In his last days, he asked that I reach out to you all with thanks. Hoping it's appropriate, I included the story below about the guy I love. Best to all --Melinda Rayburn Smith

David L. Smith
March 23, 1955 – January 18, 2024

My beloved David has died. He struggled increasingly with lymphoma and associated
lung complications. He leaves behind a sad but grateful wife, partner, and fellow
adventurer and two crazy spaniels, cherished family, friends and colleagues. We miss
him greatly but take comfort that he is no longer struggling.

David was an engineer. He loved measurements.

 We met 50 years ago. The moment I laid eyes on David, he didn’t have a
chance.
 We moved 11 times in 44 years of marriage. This included 3 countries, 3
apartments, the first one over a garage, 8 houses and one beach house.
 As an engineer, David worked for numerous companies, including JBL in
California, KEF in the UK, Snell and Bose in Massachusetts, McIntosh in New York
and PSB in Canada.
 We’ve had five spaniels, two American and three English.
 Lucky me, he had one wife.

Work travel took him to China, Japan, Taiwan, Singapore, EU, UK, Canada and
throughout the US. When I asked David what he enjoyed most about work, his reply
was, “Being surrounded by people who kept me on my toes.”

I have always considered David the consummate Renaissance man. His interests and
talents ranged from drawing to piano playing, photography to political junkie, kayaking,
rowing, bird watching, biking, hiking, ping pong…

And, of course, collecting. David collected cameras, watches, radios, amplifiers, pre
amps, speakers, LPs, magazines, books… He loved to find quality old stuff and repair
it, use and then place it lovingly on a shelf. A day before he died, David mentioned that
he wanted to start collecting old light fixtures. I am not certain if he was kidding.
Probably not.

David was hospitalized for the last two months of his life. We are incredibly grateful to
the staff ranging from the meal order taker (lots of milk), to the highly professional
oncologists, pulmonologists, cardiologists, hematologist and hospitalists. Top on our list
is the nurses and therapists who treated his failing body and both of our souls. Thank
you all.

We were asked many times during David’s last months, “What was our secret to our
long and happy marriage?” At first, we just shrugged, but soon realized we did have a
good answer. “Laugh together often and genuinely.”
David, I promise to continue to do so.

With love and gratitude, Melinda

----UPDATE-----
While the original question verted on technique to analyze ripple induced by 12VDC to AC 230V inverter on the input 12VDC, THE TOPIC moved on solve the problem.

I've solved it.

Brief recap
- From AmyAlice post I got suggestion to try to eliminate negative ripple with diode SB140 (from aliexpress, maybe fake?). FAIL.
The negative ripple is still present. The problem is the ripple pass over the regulator of Arduino.

- Together with SB140 Ive tried a NANO V3 BOARD modified with one of each .1, 1, 10, 100uF capacitor all together, in parallel, packed in one big cubic cap soldered between pin Vin and GND of the PCB (shortest path possible to reduce inductive downside). FAIL.
The ripple is still the problem and the caps seems not sufficient to shunt HF to GND. The diode doesn't make any difference.

- The ISOLATED DCDC, in this case this general AC/DC input to 5VDC USB-A output (optocoupled) worked. SUCCESS.

- Ive prototyped the ultimate solution BUT probably I will never implement. It was the last thing to do if nothing would worked. Here the layout. It is composed by 2 relays and an 230VAC to 12VDC transformer. When INVERTER turns on, AC trigger the first relay to disconnect NANO from battery source and then connect to the AC/DC 12V source. So when Inverter is off, the ripple is absent and the lifepo4 system power it up. When ripple and so inverter starts, it switches to AC rippleless source. With general ON/OFF switch.


------------------------------------------
Hallo,
I've bought this oscilloscope (ZEEWEII DSO2512G) and set to AC coupling, 10x probe.
But I dont know how proceed in a reliable way.

The problem is not strictly inherent to audio world but other comunities can't help.
I've got a ARDUINO NANO board connected to 8 DHT22 humidity temperature sensors.

Changing PSU influences the output of sensors. My choice PSU (13V>5V dcdc) fails many times each read cycle. The best is achieved with a 5V powerbank.

The situation is:

• powerbank, no reading fail at all
• 230v to 5v 1A apple transformer, fail just one sensor, like 1 time in 30 cycles or more
• dc dc fails a lot, like multiple sensor each cycle every cycle
• DIY L7805 regulator board fails like the dc dc

I would like to investigate PSUs and THAT'S THE TOPIC

So... can you help me to put down a method to investigate in that?
Since supplied current is not the problem, what remains is voltage ripple.

Im not sure if my DSO (120MHz 500msas) can do the job....

I think that FREQUENCY of ripple is the problem that interferes with proper sensor reading.

But Im really newbie in Oscilloscope world and PSU output analysis.

Thanks is advance
Gabriel

Hello and greetings from Brazil!

I'm a Computer Engineering student and I've been playing guitar for almost 12 years. Recently I started a journey to build my own looper pedal for guitar. I know it may be a long shot - when experienced people hear "loop pedal" they go "why though? they're so complicated and the DSP/programming is so advanced you're better off just buying one" - but I'm willing to fail multiple times in order to learn. This has been a great learning experience, and I've learned a lot more regarding electronics and op amps than I did in class.

So far I haven't been able to go past the input stage, that's why I'm joining the forum, it seems to be crowded with good & experienced people.

Gday!
Long time observer, but infrequent poster.
recently i have been diving into all the youtube videos about diy tweeters and planar speakers.
particularly the work of joppe peelen which i have throughly been enjoying! (do check him out if you are not familiar, tho i think this unlikely 😛 )
I have an old set of original AMT heil tweeters, sadly one of the diaphragm is damaged, it has several small tears in the pleats, im going to try and repair it, but i really dont see it being salvagable,
seeing as they are the original diaphragms, i imagine if one is damaged it means replacing them both so they are matched ~$400aud. (ouch, budget is tight)
after watching all the videos and peeking about some posts here, im wondering if it would be feasable to try and make some diaphragms myself and if so im wondering if someone could point me in the right direction.
i have freinds with laser engravers, cnc machines, 3d printers etc and an extensive collection of gadgets and tools.
its always been a dream to make a speaker from scratch(ish) and i feel this could be a good start, or is it to much trouble and costs to be bothered with?
joppe makes it look so easy sometimes!

kind regards
lemonfuzzy

So, I'm rebuilding my door panels and looking to mount my midrange high in the door.

I'm fortunate to have a big cavern there to work with, so I thought it would be cool to 'go stealth,' mounting the driver from behind the panel, chamfering (rounding over) the edge--kind of like this:



I'm wondering about the off-axis response, particularly on the driver's side.

Do you think there would be much difference in the off-axis response (~45-60 degrees) between this configuration (rear-mount) and a more customary surface mount?

Thanks for your help!

I got a Sansui SR-2050C record player that was given to me in 2017. I restored it and noticed the speed was slightly slow. I tried a new belt given the one on it was a little loose and that didn't help.

The motor spins as free as it should and the platter does as well.

I figured the slight speed difference must be within some tolerance, however it's a difference I can easily hear.

My cure was to take a Bogen CHS-60A amplifier and make a variable frequency AC supply out of it then set the frequency to where the platter spins at 33 1/3 RPM and the speed is correct on the 45 RPM setting. Needed a frequency of 61.75Hz.

Anyways I'm thinking of moving the record player to my bedroom and I don't have any space for the supply nor do I need another heat generator in my room as the tube amp does a good enough job by itself of heating the room up.

I was looking at doing this to my RCA 45 player.


I then thought why not do it to the Sansui.


Here's the schematic.





The relay looks like it operates on 50Vrms and the auto shut off arm raiser operates on 100V. So in order to keep those circuits intact I'd need a transformer with dual 50V secondaries or a 100V center tapped secondary. That said would it be possible to use the 200V tap on the 120V line and use the 100V tap to power the relay?

Also if I use that motor controller I'd need to figure a way to make the 33/45 buttons actuate a switch that changes the motor speed as currently the switch moves the belt to a different motor pulley step.

What easily sourced motors are out there that would work for this or is there a cure for the speed issue using the stock motor?

Now if I could find another small function generator kit I could use a small amplifier that puts out 45Vrms at about an amp or so then connect it to the 100V tap while moving the circuit connection to the 250V tap.

Hello. This is my first post here and I hope you like it. After taking my JBL ES250P subwoofer (12", 250W, 4 Ohm) to two authorized JBL technical support centers, it was found that the amplification board was defective and could not be repaired or spare parts were available. So I decided to try to recover this excellent subwoofer myself and it worked very well. I will share here what was done.

🎯 Objective​

To replace the faulty amplifier board of the JBL ES250P subwoofer with a new board based on the IRS2092S, ensuring the retention of all original protection features and optimizing thermal dissipation for safe operation within the subwoofer's sealed enclosure, without forced ventilation.

🧱 Original Configuration​

• The JBL ES250P comprises three main boards:
  1. Preamplifier, Filters and Limiter Board: Handles signal input, control, and crossover functions.
  2. Power Supply and Protection Board : Manages rectification and filtering with capacitors.
  3. Amplifier Board (see below): The original board was damaged beyond repair and unavailable for replacement.

🔁 Amplifier Board Replacement​

• Chosen Replacement: Chinese L30D Module (There are already some discussion forums about this amplifier here at diyAudio)
  • Based on the IRS2092S Class D amplifier IC.
  • Hybrid architecture combining elements from Infineon's designs:
    • IRAUDAMP7S: Manages input and control (pins 1–6 of IRS2092S) and +15V Vcc power supply (pin 12 of IRS2092S).
    • IRAUDAMP9: Handles output stage with totem-pole BJT + IRFB4227 MOSFETs (pins 7–11, 13-16 of IRS2092S).
      

🔥 Initial Thermal Challenges Identified in L30D board​

1. Vcc Power Supply (+15V)​

• Originally implemented using (see IRAUDAMP7S):
  • R114 (1 kΩ / 5 W)
  • Z102 15 V Zener Diode
  • Q105 TIP31 configured as an emitter follower
• Resulted in excessive power dissipation (~3.6 W) in R114, leading to significant heating.
  
  

2. Capacitors CP5 (bypass filter for Vcc supply) and CP6 (bootstrap)​

• Electrolytic capacitors rated at 47 µF / 63 V (as per the Chinese PCB version).
• Experienced considerable heating due to high-frequency ripple and 400 kHz switching cycles.

✅ Implemented Modifications for Thermal Optimization​

🔋 Vcc Power Supply Replacement​

• Removed the original TIP31 + Zener + R114 configuration.
• Introduced a XL7015 DC-DC Buck Converter Module:
  • Input: −75 V
  • Output: −60 V (=15 V relative to −75 V)
  • Provides ample current to power the IRS2092S and totem-pole stages with minimal heat generation.

🔧 Capacitor Upgrades for CP5 and CP6​

• CP5:
  • Replaced with a 10 µF / 25 V Tantalum Capacitor.
  • Added a 1 µF / 50 V Ceramic Capacitor in parallel.
• CP6:
  • Replaced with a 22 µF / 25 V Tantalum Capacitor.

✅ Outcome: Eliminated noticeable heating in these components.

🧠 Integration with JBL's Original Protection System​

🔐 Retained Active Protections:​

• Temperature Monitoring: Sensor relocated to the new L30D module's heatsink.
• DC Output Detection: Continuously monitored through original circuitry.
• Output Short-Circuit Protection: Ensured through original circuitry.
• Idle Timeout: Activates protection after 10 minutes of inactivity through original circuitry.
  
  

🛑 IRS2092S Shutdown Implementation (Extern SD):​

• The original JBL protection circuit outputs +15 V upon fault detection.
• This signal directly controls a transistor (2N5551) circuit that pulls the SD (Shutdown) pin of the IRS2092S to -5V, effectively disabling the output amplifier during fault conditions.

🔴 Protection Indicator LED:​

• A red LED was integrated into the protection circuit in case of SD (external or internal), using a BC557 transistor.
• Provides a clear visual indication when the system enters protection mode.

💡 Physical and Thermal Customizations​

• LED Placement:
  • Utilized two existing mounting holes from the original JBL amplifier PCB:
    • Installed the L30D's original green LED (indicating active PWM) in one hole.
    • Installed the new red protection LED in the other hole.

• Mounting the L30D Module:
  • Drilled two new holes in the JBL's metal backplate to secure the L30D module.
  • Mounted the module via its heatsink, utilizing two pre-existing holes in the heatsink.
  • Applied thermal paste between the L30D heatsink and the JBL metal plate to enhance heat dissipation.

✅ Final Outcome​

• Successfully restored the JBL ES250P subwoofer to full functionality.
• The L30D amplifier module operates now with enhanced thermal management and integrated protection features.
• Achieves optimized power consumption, cool component operation, and reliable performance.
• Retains original subwoofer behaviors: automatic shutdown, output relay control, and comprehensive fault protection.

This comprehensive guide aims to assist others facing similar challenges with the JBL ES250P subwoofer, offering a detailed roadmap for effective amplifier module replacement and system integration.

My second marriage, with a American woman btw, blessed me with a generous mother-in-law. She bought me a HP15C, and it followed me through thick and thin, surviving the marriage by almost 20 years, only to be lost in my suitcase en route from Georgia, the country-not the state, to Norway. Actually it disappeared in St. Petersburg, Russia, never to be seen again. I bought a new one, actually second hand, but anyway it was received with gratitude and worship. My two daughters have graced me with a full four grandchildren, some of whom have rather sticky fingers. Anyway, my second HP15C magically vanished during a visit, also never to return. My third HP15C, I`m almost willing to admit, I have managed to loose myself.

So to my question: Do I have any thankful customer in the US who are willing to buy me one and ship it? I would prefer a nice looking unit, preferably with the sleeve intact, but it goes without saying that if not that`s not a dealbreaker.
I realise many of you will wince rather loud about my misfortune, or unability to look after my gear, but I can assure you, it`s not a situation I cherish to be in.

Offers are kindly asked to be sent by PM.

Gloating is allowed and even encouraged here.

Regards
Roar Malmin

Hi all,
I’m working on a Marantz HD-DAC1 that has two persistent issues with its headphone output:

1. Colder, flatter sound with noticeably less volume and body (3 to 4 decibels less) compared to a second, identical unit I own.
2. Audible static/hiss at 100% volume with no signal playing — not present on my other unit.

I connected both Marantz put both volumes knobs all the way to 0, then used one of the remotes to increase the volume to 25% (Both volume controls went up together) which clearly let me hear the difference in volume.

What I’ve done so far, taking boards from my good unit:

• Swapped the DAC board (CUP12688Z)
• Swapped the power supply board (CUP12689-2)
• Swapped the headphone amp/bias board (CUP12689-3)
• Swapped the front panel and logic boards (CUP12687-2 and COP126878)
• Swapped the transformer (CLT5P055ZE)

None of these fixed the issue. The only original part remaining is the mainboard (CUP12689).

Headphone used is a Beyerdynamic DT1770.

I believe only the headphone output is affected, when connected through RCA output they sound identical.

• I did replace C958 and C968, but didn't make a difference.
• Bias is set correctly and matched between channels

Any help tracing the signal or suggesting next test points would be greatly appreciated!
Photos available on request.

This is the service manual i'm using -> Marantz HD-DAC1 Service manual

Thanks!

Just after a long long Linesourse diy build, find out that some drivers must have to much undertones. "in them selfes"

Lika a Piano, but wrong....Hard to explain.
The measurement are really great, but high SPL not, something isent right!

It´s like drivers have to long undertones, that makes the sound "blurry/long" and makes sound unpleasant to human ears.
Driver MMS are 6,5 g and driver are peerless_fsl_0512r01_08

Still fantastic on voice-range, like "in a center"

Some years back I was at a friends shop and listening room and we were working with some Altec 15" coaxes that were missing their horns. Someone there said he could 3D print news horns. I said "Great, can we do a soccer ball pattern?" He said to send him the drawing, which I did, but never heard back. I don't know if they got printed or or even modeled.

Fast forward about 12 years and I now have a 3D printer and can bash and thrash my way thru drawing in Fusion 360. So I jumped in. What would they look like? I have some renderings to show, and am printing some tests at the moment. The geometry was much more complex to draw than I anticipated, and my limited skills didn't help. But here they are.
The reason for the truncated icosahedron (football) shape is that the pentagon and hexagon fit together so well on the surface of a sphere, no gaps. This shape also makes it easy to do a "sort of" round multi-cell horn. I have drawn some other shapes - all hexagons, circle in the middle with arcs around the edge and some others, but the soccer ball shape looks the coolest. 🙂

Below you can see what the throat looks like. This is for a 1" driver and you can see how the pentagon and hexagons have been brought into rounded shapes to fit the round opening of the driver exit. No wasted space. You can also see that the fins are brought to a point where they face the driver exit. Finders crossed that works.

Tomorrow I should have some photos of the test prints. Right now the flange and the start of the throat are test printing.

SWTPC Tiger Amp Madness!

There are several threads on here about various Tiger amps that were construction articles in
Popular and Radio Electronics back in the late 60 and early 70s. Many people have commented
about how they brought back memories and how they went up in smoke or
even (probably brief) flames. I'll share some pictures here for laughs.

I built and repaired the Lil'Tiger and Universal Tiger (UT) (stereo version) many times. I scratch
built the larger Tigersaurus that never failed.
The UT (stereo) I worked on is my parent's amp and over the years I've picked up a few on ebay,
and various members and friends have given more to me. Tubelab (George) here sent me
two nearly completed UT boards and a pair of outputs transistors from 1976.

Michael Chua (Ampslab) sent me 5 pairs of much newer output transistors from the 1990s.

A local friend bought a pair of Plastic Tiger boards years ago that he tried to run on +/-45V not
knowing that the 40V in the article was a misprint and should have been +/-30V - his went up in
flames on turn on. He later had plans to build many more amps and offered his home etched boards and parts.

I was given a UT MKII mono block with incorrect output devices, I'm sure that it failed at
some point.

Here's the basic schematic of the original UT used in both the mono block and stereo versions, the boards are the same:
https://www.diyaudio.com/forums/att...217283-tiger-amp-madness-pe_oct_1970_pg32-jpg

The UT came in an open chassis mono block version and a closed chassis stereo version.
The stereo version used the same power supply but it was shared between the channels.
The mono block had one transistor per heat sink while the stereo version had the same
heatsinks but with 2 outputs on each one. They also deleted the thermal cut off in the
stereo version.

I bought this stereo UTS on ebay and it looks exactly like ours did when it failed, completely
burnt R12 and R14 with the board being charred even on the back side.
It is interesting that at audio frequencies and full power simulation shows about .9W in
R12, R14 and about the same in R15 and R16. The oscillation must be at high frequency
since plastic caps C3 and C4 melt and act to protect R15 and R16 forcing more power to
R12 and R14. The next and last revision of the UT increased R12 and R14 to 2W but left
the rest at 1/2 W when they also should have gone to at least 1W.
Here's a picture of the UTS from ebay with burnt resistors and melted caps on the top board:
https://www.diyaudio.com/forums/att...0684d1572213354-tiger-amp-madness-uts-top-jpg

The next is a close up of the top driver board:
https://www.diyaudio.com/forums/att...572213747-tiger-amp-madness-uts-top-board-jpg

An odd thing is that often one channel has severe damage like the top board but then
often there are damaged parts in the other channel. I don't know the details of how this
amp from ebay failed but the lower board has R13 slightly burnt. I should test all the
parts on that board. R12 and R14 are mildly burnt and the caps partially melted:
https://www.diyaudio.com/forums/att...572215741-tiger-amp-madness-sut-bot-board-jpg

When our amp failed, back in the early 70s, I did the repair and wrote this letter to SWTPC:
I found this letter recently in a folder with equipment manuals and it is very interesting to
note that the diff pair transistor Q2 failed, as well as the feedback shunt resistor R8 and a
mild burn to R12 and R14. The violent HF oscillation in one channel leaked into the other
channel. It is also interesting that both drivers failed in the badly damaged channel but
only one output device failed since probably the negative rail fuse saved the other output
transistor. I was 12 years old when I built that amp and 14 when I wrote this letter:
https://www.diyaudio.com/forums/att...7d1572214249-tiger-amp-madness-uts-letter-jpg

More pictures of the Stereo UT:
Front, ours had a stick on brushed gold front panel but otherwise was the same:
https://www.diyaudio.com/forums/att...98d1572215850-tiger-amp-madness-sut-front-jpg

Back:
https://www.diyaudio.com/forums/attachments/solid-state/790699d1572215913-tiger-amp-madness-uts-jpg

This one, actually a pair from ebay were built by Trout Audio Labs:
https://www.diyaudio.com/forums/att...00d1572216040-tiger-amp-madness-sut-trout-jpg

Here is the other in the pair from ebay, this one did not come with boards:
https://www.diyaudio.com/forums/att...01d1572216164-tiger-amp-madness-sut-2-top-jpg

Few years ago, we had enormous fun in funny named thread : F4 Beast Builders

Well, you can call it Group of Hysteric Housewives Brainstorming 😛

Result of that was that I had myriad of back of napkin sketches, and after these I started simulating ...... and simulating ... and simulating

After myriad of sims ( out of sheer enthusiasm I even made pcb files for some of iterations), I finally had made nice smallish channel pcbs, containing OS having different-ish approach to biasing than Papa's original XA25, while FE was in principle same as Papa's, but with few beautiful quirks, of which I was damn proud (yup, Mighty ZM reinventing Da Wheel, time and time again)

And they were sitting, populated, on my shelf ........ always being pushed to bottom of list; I knew they would work, but somehow I wasn't content with overall picture

Now, recently - besides revising biasing mechanismus for SissySIT ( resulting in R.3) and few other amps, I also made FE called Plethora of Pinjatas ( or just Plethora, short) and found interesting to combine it in sitting Babelfish XA25 project

Plethora Fe having both SE and Bal inputs as matter of choice, called to adding another "2" in name , so result is Babelfish XA252

Plan is also to have iteration of DEF OS ( real SIT, no emulation in form of Schaded Mosfet), thus addition of "SIT" in name, so Babelfish XA252 / SIT

Find enclosed cumulative schematic, and will do edits of this post, if and when needed

OK1-OK2-TH1 .......... 10A limiting circuit, Savior of Our Souls, blatantly stolen from Pa 😛


amp is phase correct , Papa's fave gigglywiggly graphs sez that 2nd is negative phase

all measurements made with SE input, neg leg input grounded


edit on 18.07.2021.

Babelfish XA252 SIT - post #64 Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET

Babelfish XA252 SET - post #119 Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET


edit on 18.12.2022.

separate schmtc for Full Mos, SET, SIT iterations, post #624

ignore notes on schematics about "do not mount" - just follow schematics

read all down for separate schmtcs, Extra-carefully made set of files, for each of 3 amp iterations

short setting procedure:
*********************
P1 is for DC Offset, P2 is for Iq


do not forget to have grounded neg input , presuming you're using it SE input, but also ground positive input, temporary

no load at output

P1 irrelevant for start how it's set

P2 set to max value - check with probes across unpopulated Rt, that one being in parallel with P2; that way pre-set is min Iq

I don't care for left-right orientation of trimpots - never taking care about that when making pcbs - too much times in my service work I

expected some logic with trimpots orientation, just to be confused and from then on, I'm just using DMM as guide

leave JP1 open for start

advisable to put temporary fuses in rails - say 2A

if you have variac, use it

of course, regular praxis - one DVM across rail sense resistor group ( + or -, irrelevant) - Iq observer

second DVM at output, offset observer

power up, have an eye on Iq observer;

DC offset for start - good even if few volts, but normal to expect few dozen of mV

now, fiddle with P2, slowly, to get half of intended Iq

observe DC offset is it still OK


give it time to develop some heat in heatsinks, then increase Iq to 75%


if everything is stable, close JP1 ( alive, no need to power off for that), try to minimize DC offset as much you can

if that is done, open JP1 ( alive, no need to power off for that), wait for some time to get closer to temp equilibrium, increase Iq to

final desired value


that's it

try few lazy powering off - powering On sequences, observe behaviour

if everything is OK, power off, remove temporary fuses, wire rails properly

proceed/repeat procedure with second channel
*******************

edit on 22.12.2023.

set of files for last iteration, Post #1386 - consider it as hair-splitting changes, gilding da lilly, whatever; ZM playing in Sandbox...

read down.....

Edit on 07. Jan. 2024.

Extra-carefully made set of files, for each of 3 amp iterations, post #1462 https://www.diyaudio.com/community/...2-sit-babelfish-xa252-set.373443/post-7560120

Edit on 03.02.2025.
Important revision of protection circuit: read post #2573, https://www.diyaudio.com/community/...2-sit-babelfish-xa252-set.373443/post-7919078

I have two about 42 years old Visaton RHT12S planar tweeters and i noticed that the output was getting less.
I measagered it and above 8 - 10 KHz was a steep decline in output which i now compensate with APO Equelizer
with about 10dB.

What could the reason be that the planar has less output? Could it be the membrane or magnets? Any input is welcome..

Recently purchased this sub and soundbar set from auction. Knowing the sub was faulty but soundbar working took a chance.

Opened the back up expecting to find a blown fuse or something as on another JBL I used to have but nothing obvious. Only thing that seems apparent is where the power input connects to the board.

Can someone advise if this is normal? If it's a quick fix with some solder? Or where I'd go about replacing the part/diagnosing the issue?

Thanks in advance!

Simple parallel composite amplifier with balanced input, based on the article "High Precision Composite OP Amps", John D. Yewen, El and WW, Feb 1987 and the application bulletin AB-051, Morgan Monks, Burr-Brown Corp., Mar 1993.

The ZD-50 power amplifier was taken as a basis, as well as the output stage of the RME ADI-2 DAC headphone amplifier. DC voltage protection at the output was partly taken from the Omicron headphone protection.

The R250 amplifier consists of: an input buffer U1, U2 (OPA1656), a differential amplifier/filter U3 (OPA1656) with A=-1, a composite amplifier U4 (OPA1612), U5-U10 (OPA1688) with A=-2.

The secondary power supply U14 is SEPIC on the TPS61175 converter, with an operating frequency of about 1 MHz. The linear voltage regulators U12, U13 of op-amps (except for the OPA1688) are built on the TPS7A47 and TPS7A33.

Schematic diagram:


Assembly:


Thermal picture:



Open Loop:


The main design idea of the R250 amplifier is minimal phase distortion.
To achieve this, the open loop gain must be maximal and linear, the phase must be as flat as possible in the range 300 Hz - 20 kHz.

Never used. 65 € + shipping

NOT For sale (anymore)
got it from the linkwitz store a few years ago
Only used for testing for a short period, then stocked
SEAS XM004 L26RO4Y
Woofers, black anodized cone