Sales site Huobix question​

---

Never mind. Got it figured out. Thanks for looking.


https://www.huobix.website


Thanks in advance.
Norm

I've disassembled a Teac PD-H500 for cleaning and a new belt and after removing the CD tray the following part came out, but I have no clue where it came from and where to put it back.

Service manual is silent about it and only shows a drawing of the complete assembly. I only know it came from the side where the gears are located.

Any ideas? I think it's a kind of spring meant to prevent the CD tray from wobbling when moving.

Dear All,
I´m looking for a Miro 1862-DAC-board and 2 AD1862 chips.
Best regards,
Axel

Hello. I recently build a subwoofer with 18in la voce. Thinking of using it for a party and do not want to risk damaging my speakers. Was wondering if there is a post showing how to build a simple and loud 2 way speaker. Since i do not have a big amplifier it should be efficient. Wanted to try a horn loaded tweeter mid and a big woofer arohnd 10". Any suggestions?

Hello, maybe a noob question but I’ll ask it anyway.

I recently took a look at allpassfilters with a few webinars and now I’m wondering if you could possibly „change“ group Delay with a 2nd order allpassfilter with high Q factor.

Allpassfilters shift the time delay of the lower frequency’s where the filter is applied.

If you use a high Q factor it would shift the time at the frequency where the filter is applied even more than below that. I attached a picture to show what I mean.

Following situation:

Subwoofer with high group Delay at for example 40hz, with a downward sloping group Delay to 80hz. (Tapped horn)

Wouldn’t it be possible to introduce an 2nd order allpassfilter with high Q at 80hz to shorten the time distance between 40hz and 80hz? I know this would result in an overall higher group Delay. But isn’t it better to have for example 50ms at 40hz and 20ms at 80hz with a 20ms difference than 40ms at 40hz and only 5ms at 80hz with 35ms? Of course you would have to delay your mains more, but my main question is if you can get tighter bass out of a sub with this method?

Greetings to all,
first thing first, I have very basic knowledge in crossover build so please be kind.🙄
A couple of years ago I bought a pair of KEF Q950 speakers really cheap. Now I want to upgrade their crossover parts to better ones to see if I will gain any sonic benefit. The reason for doing this is that the crossover is rather simple and uses very little part count, hence small fundings needed and not that complicated to be done from me.
The schematic and a picture of the crossover is in the attachment.

I did a little research of my own about sound signatures of different components. Taking into account on how the sound can change and what sonic difference I'm after, I have already bought the capacitors (30uF Jantzen CrossCap/ 5.6uF Jantzen Superior-Z), resistors (Mundorf MOX 10W), Jantzen brass binding posts.
I'm very sensitive to harsh treble so that is the main aspect that I am trying to avoid. Also I would appreciate some additional juiciness in the midrange and guitars / piano.

Now comes my concerns about the rest of the parts and where I need the most help.
For the inductors I can't measure the DCR for now(just ordered some LCR meter from china). But if we hypothetically say that they are equal in DCR:
1. If I change the coil for the low frequencies from the stock ferrite core inductor 2.0mH/DCR?/ AWG ? to an air core Mundorf 2.0mH/0.45ohm/18AWG how will this affect the sound? Will it be worth the effort?
2. If I change the coil for the low midrange from the stock ferrite core inductor 0.85mH/ DCR?/ AWG ? to an air core Jantzen 0.85mH/0.45ohm/18AWG how will this affect the sound? Will it be worth the effort?

Any advice will be appreciated!

I just repaired this awesome cassette deck made in 1978. The brand is totally unknown to me and I wasn't able to find who is the actual manufacturer of the deck.

Posting some pics in case anyone could help.

Hi guys, I'm new here.

I struggling to find an answer for a basic question online.

I'm currently running two AVE bassboy 18inch powered subwoofers and two powered psx112 wharfedale 12inch speakers via xlr cables.

I've just had a a friend offer his two powered wharfedale ax215 dual 15inch speakers to me.

I've noticed that at the back of each ax215 speaker , they have two separate xlr inputs labeled A & B.

Can I just buy a couple of Xlr splitters and connect the ax215's to my AVE subwoofers? Or is it more complicated?

Any help is greatly appreciated

Selling 2 x anaview AMS 0100 in perfect condition. Price Euro 2 x 160.-

Hello everyone.

First, sorry for my probably not very good english.

I have 2 different DVC drivers for different subwoofer/bass speaker projects (Ciare HSG200-44 and Ciare HSB320-44). I simmed only dividing Re by 4 but i just read that Bl also has to be divided (by 2).
However i still don't know how to sim with 2 separate amps as the BL apparently also has to be divided by 2 (same for Re) which doesn't match with Qes.



Btw, I have to say i still have doubts as many 4ohm drivers often have close Bl characteristics to the 8ohm models (for drivers that have both 4 and 8ohm available).
And if Bl has to be somehow proportional to Re, is it really possible for a 8" Deaf Bonce driver to have 2x1ohm impedance (Re not specified) with a Bl of 18,4 and a Qts of 0,55 (while this Bl would mean a qts of around 0,26) ?

Could someone help me to make it a bit clearer before i start building everything ?

Thanks a lot for reading.

The historic site of Jean Marc Plantefeve will change host, its old site will therefore no longer be accessible, here is the address of the new one
https://2adiy.ovh/

HI, is the RCA output of the same quality as the XLR or does it go through an additional stage like in the Cambridge Dacmagic with XLR outputs?
In this case it would perhaps be better to build an XLR > RCA cable.

Thank you

I know the loudness circuit is generally embedded in the preamp section of the amplifier system. But I wonder are there any passive devices that are installed in the passive crossover of the speaker and allow the speaker to perform as if it had a loudness compensation itself?

The device should have the ability to vary its resistance (inversely either current or voltage of the amplifier’s output) and be connected only to the woofer.

I'm trying to simulate this very interesting circuit by Graham Maynard. Essentially a discrete op amp with Class A output stage.

It's oscillating pretty nastily in LTSpice. I've tried higher values for the feedback cap and lower values for the feedback resistor (lower gain), and it just gets worse. With even 27pf in the feedback loop, it simply doesn't work at all - only oscillation.

Any thoughts on why it's not working? Maybe it needs some sort of internal compensation?

For sale, JBL 2450 J with recent Aquaplas new diaphragms. With the new diaphragms the JBL becomes an 8 ohm CD (H version).
I have 2 for sale for 800.00 includes Fedex ground shipping in the continental US.
Also if someone is in Southern California and wants to pick them up I will throw in two nice Goldwood 2 inch waveguide's at no additional cost. The Goldwood's work well down to 550 hz.

Hello,

I've recently got a 5V bluetooth receiver audio board to play music remotly to my speakers, before I soldered the power I tested it via a 5V phone charger and it worked fine..
When plugged into the DC-DC step down board the BT receiver board is making first high frequency noises and then it's just buzzing.
Any ideas how I could fix that problem?

Bluetooth board:VHM 314 Bluetooth Audio Receiver board Bluetooth 5.0 mp3 lossless decoder board Wireless Stereo Music Module-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group

Wiring diagram:

Hello! Looking to buy a Flex Eight. If anyone has one let me know 🙂

Paraflex & Super Planar High Order Compound QW & Compound Horn variants /dev/builds

The builds you will see in this post are based upon designs provided by yours truly😀 and skillfully handcrafted by a man named J.R Vansickle of Paragon Concept audio in North Carolina ... Mr Vansickle has excellent woodworking skills, a great ear, and also a strong background in Home/Audiophile & Car Audio😎 ....

The compound loaded concepts discussed within this post started off as a configuration that had repeatedly proven itself to be viable (and practical) in simulation, so it became apparent to me that this was something worth exploring.... During this time Mr Vansickle was coincidentally receiving many requests for PA cabinets....

We had already worked together on a few designs that turned out well in the past, and now it was time to try something new

The compound loaded simulations looked like they would deliver exactly what the application called for so Mr Vansickle built the first set and they worked like a charm! .. ... A few of these successful designs are currently in use by a few of Paragon's customers in the Eastern United States ..... If the cabinets did not sound right to his ear we would have fallen back to simpler designs for the customers but the first set of these that he built sounded fantastic, so we went with it!


At this moment there are no detailed measurements, only a few crude approximations and a few low-res videos of them in action, but that should be remedied as Mr Vansickle has vastly increased his commercial shop space (new location) and is about to be outfitted with some gear that will be able to produce the detailed measurements that we sound fanatics desire🙂 ..







First of all to be fair i have to say that this is not a new idea by any means, compound horns have been around for a long time so i cannot take credit for that..... It is an old idea but sometimes old ideas are worth revisiting because new levels of performance are made possible with the use of modern drivers and modern software..

In other parts of the world some people have recently constructed 6th order subwoofers and bass cabinets that they call "Planar Wave Horns" , the plans have been floating around for a while but the popularity has not caught on here in the United States as far as i can tell ....... I pondered that higher performance might be possible if i swapped out the rear resonant chamber/vent set in the Planar Wave Horn design and replaced it with a true quarter wave resonator (with or without expansion) ..... I tried this out in Hornresp (and yes you can do this in OD mode it just requires some creative usage of a vented rear chamber )..

The result is that you can utilize the resonance of the smaller chamber tuned to a higher frequency to fill in the dreaded response "hole" which typically plagues Back Loaded Horns , Rear Loaded Horns , TLs (QWPs) , Scoops etc .......... It is interesting that filling in this "hole" not only increases the usable bandwidth but also seems to improve general efficiency just a bit as well ....

Here is a generic sim to demonstrate this useful effect:



As it turns out the bandwidth can extend well beyond the "hole" that we filled in with our upper resonance ..... This makes it possible to create something like a high performance Kick-Bin cabinet with bandwidth that extends surprisingly high ....

OR
If gain and output take priority over bandwidth (as it might in a subwoofer design) then you can make that upper tuned chamber larger or longer which increases efficiency of the system while sacrificing bandwidth ......

Note: I have been calling this upper tuned chamber the "front chamber" or "MF waveguide" for lack of a better term at the moment .... and I have been calling these designs "SUPER PLANAR"


Here is a generic example of a subwoofer based upon this design can do:

This design can under the right circumstances compete directly with Front Loaded Horn and Tapped Horn designs of the same cabinet volume and tuning, loaded with the same driver but only if the driver has the appropriate T/S parameters for this design ...

In the case of a low tuned subwoofer loaded with a large diameter driver the cabinet volume requirements can be quite large unless you choose a driver with high motor force (relative to the diameter of it's diaphragm) and this sort of thing simply wasn't possible back in the 1930s (or whenever it was when the first compound horns were devised) ...

We will revisit this idea as a subwoofer later because we did produce a set and they work well , but for now we shall go back to kickbin designs because that is what we started with and we don't want to get ahead of ourselves ....

To demonstrate how the Super Planar can compete directly with a FLH (or Tapped Horn in some cases) here is the CV B36A (which i use for a kickbin) compared to the Super Planar using the same 188EB driver and the same cabinet volume .... I prefer the Super Planar's response here ..

Not bad eh?😀 Ideally the upper response would taper off and produce something roughly resembling a "house curve", but technically due to the 18" driver this one will be limited on the upper end (certainly no higher than 500hz without becoming too 'beamy").. ....... There is a way to have some amount of control over the contouring of the upper response, and it can be seen as a red panel in the following sketch .. More explanation on that later with accompanying Akabak modeling to demonstrate alterations in the response contour ......

Here was the sketch I came up with for J R Vansickle's very first SUPER PLANAR build! This set worked very well and ended up being used as Wideband Kickbins in a night club sound system installation located in North Carolina ...



As you can see this sketch originally gave us the option of building it without the front chamber (waveguide) which would have made it a plain offset-driver Back Loaded Horn but with the front chamber included it becomes a Super Planar BLH.


The red panel can alter the midrange contour considerably but at the time Mr Vansickle wasn't set up to take detailed measurements so we left the panel at 50% depth of the waveguide because we knew that it would produce sufficient results ... With dual Dayton PA310 drivers the response reached reliably up to nearly 1khz ! We were pleasantly surprised by this .

I modeled this in Akabak in an effort to get an idea about how the contour would be altered by changing the length of our red panel ... I suspect these curves are a bit exaggerated (i did squash them vertically) but it gives you an idea of what is possible .... We are calling the red panel the "H-Panel" in this comparison...




I used a very non-scientific method in an attempt to get an idea of where the dips and bumps in response really landed in the real world cabinet ... I did this by running Mr Vansickle's recorded low-res cellphone video files (of multiple music tracks being played over these speakers) past my software RTA in peak-hold mode ...... I am happy to say that there doesn't appear to be any holes in response but there is what looks like might be a bump between 250hz-280hz and a dip centered around 310hz followed by another dip around 500hz but it is hard to say if the anomalies were just a feature of the music being played or some room interaction or boundary bounce or something else like the response of the microphone on his cellphone ..... Like i said it is the furthest thing from scientific 🙄 but promising.

Lets move on to some build photos:




He made this cabinet out of 3/4" ply (the dimensions were calculated for 1/2" ply , so needless to say the 12" drivers fit VERY tight but he made it work


You can see some more of the internal bracing on this next photo






These are 3-way cabinets with a Selenium D250X midrange compression driver coming in at right around 1khz and a Selenium D220Ti coming in at around 4khz-ish ...... The PRV horns that we put these drivers on produced responses that were very far removed from published curves 😱 (and this was obvious even without detailed measurements) so we had to redesign the crossover .... The woofers were actually run "Dry" and i didn't want to go into too much detail about the crossover network here (since it is unrelated to the compound loading concept) but in the end our filters were kept simple and sweet......

NOTE: Without the recommended HL14-25 horn the D250X does not want to reach very low.... In the PRV horn that we used there was a tremendous honk at 1khz, and if we reduced the series capacitance enough we could tame that 1khz bump however when set up that way there was no chance of significant output from it much below 1khz, so it was a good thing that the PA310s had no problem reaching up to that range despite the fact that they were recessed behind the waveguide which composes the front chamber on this cabinet .......

ANOTHER NOTE: On the PRV horn that we used the Selenium D250X is very loud (as if we traded some bandwidth for efficiency perhaps) and so it did require some padding/attenuation to better match the 220Ti and the parallel PA310s..

YET ANOTHER NOTE: We found that the D220Ti needed to be phase flipped in order to integrate smoothly with the midrange ..



AND NOW FOR SOME SUBWOOFER CABINETS

The goal was to build some subwoofers that could fit underneath the stage.. These would be installed at the same nightclub where the Super Planar tops were going to be used .... There was 23" of vertical clearance underneath the stage, and a heck of a lot of depth that we could utilize ....... Due to the height limitation and the design of the cabinet we knew it was going to be a tight fit for the driver so we came up with a few different baffle shape options ....

Mr Vansickle chose the "S" shaped baffle in the following sketch



We went with a Faital Pro brand driver but there are many more options that will work as listed on the right, some are crossed out because their excessive mounting depth means that they won't fit unless the box dimensions are made taller . ...



Many (if not the majority of) PA sub applications don't require such a low tuning , so in that case the cabinet would not need to be 60" deep, the path can be shortened a bit....

. These are some BIG boxes!😱






Lovely holed braces







Yes yes, I know ... He chose this banana jack binding post set (instead of Speakon) for a good reason i am sure, possibly having something to do with the tight quarters underneath the stage ...

For sale,

An absolutely fantastic piece of art.
The Audison HV Venti 2 channel audiophile audio (new price about 13.000 dollars).
This is the best amplifier you can buy in terms of sound quality.
The amplifier is very heavy, so it's preffered to pick it up at my house. Insured shipping is possible, but it will be expensive.

New price is about 13.000 dollars
My price is 3500 dollars.

It's fully functional and sounds fantastic!

For more information or interests, feel free to send me a message.

Me and brother in law had talked about installing in his Tacoma the original JBL premium speakers which are 45-50watts each. Suggested 200watt amp too low would be at capacity maybe leave room by getting larger amp like 3-400wattX4 instead he wants do 200wattX4. I offered my used Kenwood kac with 900watts maybe a bit much but then he went off like this is he talking straight, feels like college class if you ever seen his other texts but I'm open minded.

Me: 200 Watts that's crazy low for 4 speakers fyi don't run minimum RMS or your sound won't be as good it could be. Speakers I put in my dad's Cobalt recently are an RMS of 60 watts but they can handle up to 180 watts and running about 80 watts to each but truck not huge space so maybe don't
Need to much power idk.

his response lol nerdy but maybe good.
Yeah, none of that is true.
Because there's no standardized way to measure amplifier output power except watts, people put too much emphasis on that number. Thing is, a Watt (W) is just the product of multiplying the measured current (amps) by the measured voltage (V).
Amps = Number of Electrons
Volts = How badly the electrons want to move

You can make 35,000 volts just rubbing your feet on carpet.

While volts are easy to come by, amps are not.

Real world result is that an expensive 25 watt tube amp is much louder than a cheap 2000 watt mosfet amp.

See I tried be simple and I don't even think mosfet uses or tubes or by his application. Yeah I always talk to him in terms of RMS but he stating zero way to measure watts. But everything based on wattage and yes you need to adjust voltage/amperage but if his speakers need 45-50 watts each I also understand him wanting a 200x4 amp would have zero room and be maxed out. Lol just never talk audio like it's college day so trying to understand history point of view really because he is often wrong and but idk this time.

Gentlemen, I have a pair of Mr. Nelson Pass A40 ClassA amplifier PCBs, which I want to offer you.

The PCBs layout is done by myself.
I have included the frontend, the backend and a simple C-R-C PSU on the PCB.
The PCBs size is: 236x85mm.

I am using "current" transistors as replacement for the transistors that Mr. Pass used in his original design.
I use - for example - MJH628X Darlingtons as Output Transistors, KSC2690 and KSA1220 instead of obsolete MPSL, …

Find attached an image of the PCBs, a "PCB - look-through" and the schematic.

I offer the pair of PCBs for 20€ (shipping - without tracking ID - and PayPal-fee is included).
If you are interested having the PCBs: give me a PM.

Best regards - Rudi

Up for sale is my Miro AD1862 I2S NOS dac with Burson V6 Vivid OpAmps:
Optionally the LM317 and VRDN PSU's can be sold with the DAC

Asking EUR 150 plus shipping from The Netherlands.

Mmats D700.1 amplifier has 0.5 dvc on the out put, plays audio but sounds like my coil is rubbing. Does anyone know what this pot is used for ? Is it dc offset for outputs?

Hello,

I have to admit, I expected more people to add 12v triggers for their DIY amplifiers, but I am having a heck of a time trying to find any information. For instance, on the back of VTV amplifiers, there is an in/out 12v trigger. I'm building my own amp, and I am designing the rear panel right now in CAD. I have it about complete besides this 12v trigger. I'm not sure what holes I need cut for the trigger- there doesn't appear to be a standard 'part' for it... are all 12v triggers on amps just some home-made design? I thought a 12v trigger system was more universal than this, as something that can be found on a lot of equipment, but I guess not?

Is it even worth it to add to my homemade amp or is there something else you all do when building your amps and equipment for home theater? Do you use 'smart' (master/slave) power strips instead?

Here is what my back plate looks like right now. I wanted to add the trigger in the obvious empty area.



Thanks!

Howdy. I've decided to build a set of Klipsch Cornwall clones as my next project. I've built two kits from CSS Audio but they come pre-cut and are pretty much foolproof. I can easily find the rough drawings of the Cornwall 1's. So I know this build is going to take a lot longer than a kit but I'm having a hell of a time finding plans for the model 3s. I've seen pictures of builds that clearly don't have the Gen 1 drivers installed so I'm assuming those builders bought the larger horns and reverse-engineered the plans. The speakers in the 1s are mounted inside while the later ones are surface/flush mounted. Can anyone point me in the direction of cabinet plans for the more recent types? I'm pretty sure it just comes down to speaker placement on the front baffle as the horns changed over the years. Thanks in advance.

December 25, 1946 - September 1, 2023

I am in mourning today. I am disillusioned. He was immortal.

Some of you may have seen the delicious pics from Munich posted recently and noticed larger ScanSpeak Elipticor drivers. Today I was notified that there is a new, and curious, midrange available.

https://www.scan-speak.dk/product/d8404-552000/

Dome, close backed, 3 Ohm minimum, power TBD. The frequency response is curious, but I can see if this is used with the matching tweeter maybe they will have the same acoustic distance, making crossover design easier?

Tube cad has this odd amp circuite using 2 tubes . At much
lower voltages should this work with using jfets ? Oh the
schematic is probably simplified and I would probably need
gate stopers but as a basic concept would it likely work.

HI All,

Seeking some help with my build... I am in the process of building my first full range speakers with some Alpair 10P's. This is also my first attempt at a ported box and I thought I would go for a SBB4 alignment.

Using a simple app and the datasheet specs, I came up with the box design in the first image below. This is in approx. agreement to what I got doing the same design with WinISD.

The datasheet specifies the Fs of the 10P as 42Hz. However, today I tested the drivers with a DATS V3 and the resonant frequency seems to differ markedly from the spec sheet - see the impedance plots below. One is 55Hz and one is 47Hz. While I know specs often deviate from the spec sheet, this difference is more than I was expecting and if correct would mean my design may not work very well. 47Hz is almost tolerable but 55 seems pretty off.

I am seeking advice on where to go from here. Do I alter the box design to suit the measured Fs or stick to the original plan? I have already cut the panels but still have the opportunity to alter the port length or make the box smaller by using some kind of internal space filler. Could the DATS results be off or unreliable somehow? I tested some 6" sbacoustics drivers as well and they were nearly spot on.

Appreciate any advice anyone might have!

I have an IMMACULATE pair, LIKE NEW, stored in a church attic for many, many moons, here on the Mississippi Gulf coast. I am looking to relocate them to a nice, warm, loving, kind home, and am accepting offers!!! Serial #'s: 01825 & 01831.

Email: johnboise32@gmail.com

I am working on building a couple pair of 2 way bookshelf speakers based on the Purifi 6.5 https://www.madisoundspeakerstore.c...rifi-audio-ptt6.5x04-nfa-01-6.5-woofer-4-ohm/ and a Satori beryllium tweeter with waveguide https://www.madisoundspeakerstore.c...bnwg-4-beryllium-dome-tweeter-with-waveguide/. I am basing it on a Jantzen audio discontinued kit http://www.troelsgravesen.dk/Purifi-6R.htm. I am planning initially anyway to biamp them with a Minidsp DDRC 24. Probably going to put a cap with the tweeter as protection since it is expensive. Madisound recommended a 50 microfarad as I recall. At any rate the port in the TG design is hard to find in the USA so went looking around and found a Chinese sight that had 65mm by 180mm which is close to the 68mm by 160 that TG specifies. The TG/Jantzen has a larger flare at the opening as well. I am wondering if the pictured ports will provide close to the response of the Jantzen? Thanks for any insight.

IRF9540 is a very good MOSFET. 150W and TO-220.

Here is shown a load of 5A with only 0.48V drop.
R1, C1 and D1 provide a start impulse for the regulator.
The regulator is variable 5-25V.

I'm always in need of various bits and pieces like 6.3V DC or 12V DC regulators for vacuum tube heater supplies, or +/-15V DC supplies for op-amps.

I see a lot of DC buck converters available at very low prices, from surplus sellers, eBay, etc. Like this one:
https://www.mpja.com/07-31-23.asp?r=393065&s=18

It says it's based on a XL4015 regulator. I looked up the data sheet, and it looks capable, with up to 7A out with heatsinking and a super low 0.3V dropout voltage. But I remain skeptical and I have zero experience building with switching power supplies, which is why I'm asking about it here.

Also, the XL4015 data sheet says it runs at a fixed switching frequency of 180kHz (144kHz min, 216kHz max). I wonder how fearsome of a switching frequency spike that is. It's low enough that I'd be hesitant to inject a big spike at that frequency into whatever preamp, etc. I happen to be building. But $2.95 for a pre-made regulator PCB is very tempting, especially since it shouldn't need as big a heatsink as an LM317-based regulator of equivalent current capacity.

Is a switching frequency of 180kHz too low?
Are there other regulator chips that are similar to this XL4015 but work with switching frequencies of >300kHz?

Is using a switching buck converter like this doomed to fail if used for a 6.3V 1A vacuum tube heater supply down from something like a 12V DC raw supply?
Does this type of switching buck converter need to be used with only about 1.5V stepdown in voltage, so that it doesn't go into shutdown from inrush current at power on?

Finally, should I have posted this in the Valves/Tubes section? I posted it here because it is a power supply question.

Yesterday as soon as i turned on my car all of my speakers started making weird noises that sounded like a techno song and then went quiet. I check my amps and the 6ch running these speaker was stuck on protect.

1. I disconnected everything from the amp except the power/remote/ground = protect
2. Just power and ground = protect
3. Took out the ground lead and tried putting it back in = spark
4. Used DMM to measure continuity = continuity detected between power and ground.
5. Opened amp to check for any burned components = nothing everything looks clean

I connected the amp to my bench power supply set at 12V/2amps and no more protect BUT i believe its due to the low current supplied. The subwoofer amp and dsp are working just fine, I put in another 6ch amp in for now and everything is back to normal on my car.

This is an MMats Hifi-6150D which i sent in for repair 7 months ago for blown MOSFETs but this happened in a whole different car/system, mmats just gave me a whole different amp. I made a post about it here a while back but at the end i just sent it back because that amp did had a lot of issues.

I want to try fixing this one myself and save the $250 service.

Pls PM if interested.
Unassembled but opened box for checking
100v/200v, Japanese manual only
All original. Except for upgraded to 2 x TUNG-SOL 6L6GC STR
Shipping from HK and PayPal

Hi,

Well I'm hoping that the title of this thread will stir up some debate !

I am expecting a lot of 'yes it is, it's a bad chip, rip it out and go NOS' but I'd like to understand the reasons behind people thinking NOS is better.

There will be some, I'm sure, who think that interpolation is just wrong and with any oversampling filter you're not listening to the real music. There will be others, who have tried it and prefer the results because it sounds better to them; whether the sound is more 'realistic' or not.

What I am wondering is, why this is? Is it, not because the digital filter is a bad chip, but, actually because it creates a lot of pollution on the power rails which affects the DAC; with the data clocked at 4fs instead of 1fs timing is more critical (jitter) and since everything is running faster more attention needs to be paid to design of the power supply, decoupling, layout, grounding and so on. If all these things are taken care of can the combination of SAA7220P/B + TDA1541A work well ? Is it really that the implementation of the SAA7220 in most players leaves something to be desired ?

Cards on the table. I have an Arcam Alpha 5 (SAA7220P/B + TDA1541A) and I have socketed both chips so I could easily go NOS and I will and compare the result but if I do like it better I'd like to know why, certainly reproducing a 20KHz sinewave with a 44.1KHz sample rate isn't going to sound good !

So, let the comments begin ...

Regards,

Jon

I want to thank Stephe for sharing the Youtube video and her adventure with the amp that I am considering to build.
I want to clarify a few quesions
1) can I use solid state diode power supply for the B+ ?
2) What about using an ac to dc power smps from Meanwell for the heaters ?
3) I notice that most output transformer show usage of 2.5 or 3.5 K output transformer . Is there any issue with 5K output transformer ?
What is the wattage of the output transformer ?

Thank you

Kp93300

https://audioxpress.com/article/fre...asure-audio-and-acoustic-measurement-software

dave

Sold
Last spare set of Miro PCM63 DAC for sale. i2s inputs on board.
Circuit design and board info available here:
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-209#post-7049224
You need a PSU and I2s source and a pair of single op amp for this DAC to function. Look at the info in the thread to see the PSU requirements.

Board fully populated with good quality caps eg. Elna Tonerex throughout, Kemet mkp caps, all the signal resistors are low noise non-magnetic resistors with copper leads, panasonic smd ceramic caps., good quality Nextron IC gold plated contacts sockets. IV resistors are high quality red PRP ones.

You will be supplied with a pair of unused PCM63P-K chips. They are 100% new, with 'virgin legs' and you will need to press the legs inwards to insert into the IC sockets. I used my own pair of PCM63 to test this board and will not send these to the buyer. These are so difficult to come by now.

IMPORTANT : Please note that I will not be providing the IV op amp.

Price is $220USD, including shipping registered worldwide. Paypal FF only please. Shipped 30+ packages to US,UK and Euro with a clean record. Pictures to follow.

Hey guys,
I'm sure some of you have gauss meters in your tool collections.
Just curious on what you use?
I'm going to get one for measuring neo magnets and some coils etc....

Post what you use and pros and cons
Thanks guys heaps!!

Hi there,

I’m interested in a pair of 2SJ28 if you have some kicking around underutilized..

Thanks!

I have some audio accessories I want to sell
1- Tango FX 40-5 for EL34, KT88 PP new fullbox - price: 320$
2 TKD 2P2511s NEW - 100$
3- Blackgate VK 47uf 160v used - sold out
4- Blackgate Không phân cực 33uf 16v NOS 120$/2cps
5-
Used Fluke 278
All features work normally, there are a few light scratches
Comes with Fluke TL175 test probe and carrying bag
Sold out

HCMC, VietNam

Hi, A couple of quick questions on OPTs for a GM70 output stage. My design has a max power output of 25W from the GM70. Ua = 770V, -65V bias, 80mA.

1. Should the OPT be spec'd for 25W + % headroom? If so, what % is reasonable to use?

2. I am targeting a 7K primary and 8ohm secondary. There are some 3.5K primary OPTs available and therefore, can I use the 3.5K primary with 4ohm secondary tap and get the same results as a 7K : 8 ohm? Is this as simple as primary : secondary ratios?

Thanks.

Hi,
I'm always afraid of using small trimmers where a significant current will flow through the wiper. Will the following approach (U1 section) be fine for biasing a CCS using a pot? The extra resulting resistor in the current path is small enough to not affect the CCS, I believe. Any drawback of this approach?
Thank you!
Jose

Hi.

I'm trying to figure out how to design some basic ported speaker boxes.

I have a pile of NITB Proficient speakers (c800) that my company was going to toss in the dumpster.

These are coax speakers, witb a tweeter suspended over the woofer and intended to be installed by using your drywall as a baffle, not installed in a box.

That being said, I've already figured out all of the fs and qs for the speakers using a signal generator, and an RMS multimeter, but I'm having a heck of a time finding a software program for MacOS or an online generator that works.

The speakers will be installed between open ceiling joists, and the ceiling are staying unfinished like that for this space.

The boxes I'm trying to create are ported enclosures similar to the Bose 301 slot style, but without the reflecting tweeters.

Can someone please point me in the right direction? I've literally spent about 30 hours flailing around without getting anywhere.

Thanks!

I want to make an in-line high-pass filter, but before I order my parts, I just wanted to make sure, it really is just the R and the C, right? There are no extra pieces that should be included for a real filter that don't exist in the educational diagrams?

Hi,

according to topic; I`m searching for one Interface for the Spectra 22/2200.

Best regards
Olaf

Just wanted to say Hi and introduce myself. Just joined the forum after lurking for some time. I live in the Bay of Plenty in NZ and have an interest in audio and car audio. At 53 I’m thinking about teaching myself about amplifier repair just for fun. I’ll probably ask some very noob questions but will do my best to search out answers first. Cheers. Stephan

I have no experience building an audio amp before but I have built a Tesla coil or two. I attached an image. Basically I want to build this video here Login to view embedded media . It is a Tesla coil fed purely on essentially a class-D audio amp. It’s a hard project to do but I have built a Tesla coil before which I have attached. The idea of attaching an audio amp to the Tesla coil is to remove pretty much all of the audio distortions. I have been teaching myself audrino coding and I am in college with one of my subjects being alternating current so I know what formulas I will be using for design. I do not know the best guide for the design of a class-D audio amp. Ideally it would be single channel, simple to build and be capable of being scaled up to higher voltages. This topology can be scaled up infinitely. Ideally mine would be small, scalable, simple and highly efficient . As a noobie to class-D amps I do not want it to go further than say 100w. But I wish the topology i choose to be scalable as I have a 1kw Tesla coil I would be connecting to the amp as a baseline. I have a small coil like the one in the video also I may choose to use.

I have wadia 860 cdp and our country uses 220 voltage. I'm anxiously looking for the Sony kss-151a laser lens optical pick up part that goes into my cdp. I want to get the real thing, not the fake one and I can't tell it apart. It would be greatly appreciated if you could tell me how to get this part. Thanks.

I've settled on Eminence Beta 12CX and PRV D290py-S compression drivers in a JE Labs style open baffle with a MiniDSP crossover. My design goals are to create a mid-range focused system for low to low-moderate listening (paper thin walls in the new apartment). So far I've only built mono systems so I'm excited to explore soundstage and imaging! I have headphones for bass heavy music, but I'm interested in exploring more jazz, soul, world and opera with this system. Note: I cannot hear past 16000hz.

I'm constructing a rig to measure this speaker 6' off the ground in my back yard. Past this iteration I'm interested in exploring felt baffles with large round over edges, but for the moment I'm content learning the ins and outs of DSP.

I just ordered two 2x15w boards from classdaudio.com to power the 12CXs/tweeters, but I also have an inuke1000 at my disposal if I need more power for the woofers. Question: I like dynamic systems, if I use a more powerful amp to power the woofers and EQ nulls will I loose dynamics? The woofers are 97db with 250watt RMS power handling. The inuke puts out about 160 watts into 8 ohms. Like I said, I'm not trying to get super loud with lean bass. Any tips for designing a DSP based system for quiet listening?

Hello
These was my first DIY amplifier , I built about 20 years a go .
Now I think to rebuild it . From beter quality parts .
Any comment welcome .
When firs I built it I used one pair power transistors but after I added one more pair which brought a lot of improvement in the sound .
More dynamic , more bass , I used +/-56V power supply with two pair 50 000uF Mepco capacitors .
I post the schematic you can take a look . No need for preamplifier , just a 10K pot. . On the input is better to use a bit higher value capacitor .
One more time any comment ,advise welcome
Greetings

I am looking for the target frequency response that it is often used by TVs or Soundbars as a sound mode usually under the title News or Dialogues.

This offers more clarity/ integibility when the broadcasted program is News or Sports.

Can anyone help? Is there a recommendation or a paper about this?

I would like to get these to someone to use, I'm no longer into building/repairing speakers.
1 pr Dayton Audio soft dome, NIB
1 pr CSS soft dome, used very lightly.

Pics should tell all. $70.00 shipped USPS Priority to the contiguous 48 states. Paypal +3%, or Friends and Family.

Working on a smps.
A pair of N channel mosfets are testing as P type?

Using Fluke 115. Red probe in red socket. Black probe in black/common socket. Meter set to diode mode.

Removed a pair of mosfets marked 1L02AB FDP

26N40 from the circuit.

The pair of Mosfets are still screwed to the single heatsink. Mosfet printing facing me.

I did the test where I short the left and center pins. I put black probe on right pin and red probe on center pin. I get OL. While keeping black probe on right pin, I put red probe on left pin and get OL. After a few seconds I move red probe from left pin back to center pin and still get OL.

Now, even after I short the left and center pins, if I switch the probes put the red probe on the right pin and black probe on center pin, I get .49v. The center pin never measures OL even after shorting the left and center pins when measured like this.

This happens with both mostets. But there is no short from the left pin to the center pin (gate to drain).

What's the deal?

anyone got a cheap source for perspex / acrylic sheets for circle template making for use with a router ,
someone you've ordered from before and it wasn't mega expensive or crap when it came.
I don't mind cutting the template myself I just need a good source ... thanks

Hi, I recently acquired a tube phono preamp and I don't want to use it just for my turntable but also for my digital sources. As far as I know, I can achieve this by feeding the signal from DAC through a reverse riaa circuit (R-riaa) to the preamp. My problem is where should I add the voltage divider? Basically there is two options, adding between the DAC and R-riaa or between the R-riaa and the preamp.

In addition, although I can find somewhere to purchase the R-riaa, I can't find anywhere sell the voltage divider and I assume I have to make one by myself. My demand for the voltage divider is simply the following. First, it is able to reduce 2V from line stage to 200mV so that it doesn't overload my preamp. Second, I prefer it to have rca input and 3.5mm rca input jacks. In this case, what material do I need? I haven't diy before but this seems to be a easy project.

By the way, does anyone have the experience of doing similar thing, what is your impression about the result and what suggestions you would have for me?

For sale are jantzen cross coil foil inductors.

2 x 0.680 mH
1 x 1.700 mH

Offers welcome.

Ex post.

Inevitably during tube builds it becomes obvious that at least 10 megohms/volt DC is needed, especially on grid circuit measurements.
So this guy, from an SS background where 20k /volt was fine, had to tool up. Went online and purchased eico 232 VTVM and micronta 22-220 FETVM.
Had to spruce up the eico a bit, HCL on the rotaries and battery eliminator- also replacing the 1% resistors that were way out tolerance- the ohms scale was egregiously off. Micronta, the other hand was pristine inside- initial readings checked out- but cleaned the rotary for good measure.

After using both-
Can say that really wanted FET meter to be the go-to, but it's sensitivity isn't as good as the VTVM when on amp grids & especially tube receiver tanks.
Of concern is decay in readings w/ the FETVM... goes up to a point, then begins to fall on the above examples... Could be a prob w/ the meter?? It doesn't have same issue other less sensitive areas. Also, meter response is ketchup bottle slow compared to the eico, which snaps up immediately w/ reading.

These are my shallow impressions thus far w/ these 2 analog meters. I'm sure digitals are different, but I prefer good analog- 2% accuracy is good enough.
Moreover, can easily identify low freq voltage fluctuations w/ analog V digital meters- JMO
What are members here using?
Jim

Having never seen an actual comparison of the same cabinet used as a push pull (PP) compared to a normal forward facing pair, decided to do it myself.

Since comparative push-pull and push-push distortion measurements are hard to locate, thought it would be good to reference Mark100's more recent work here too in post #27:

https://www.diyaudio.com/forums/sub...normal-distortion-compared-3.html#post6609651

PP proponents claim large reductions in distortion due to the cancellation of the differences caused by non-symmetrical cone movement, but without a comparison of the same speaker in the same cabinet, other design features such as a front plenum or horn loading make the reductions hard to quantify.

In my test, a suitable sized rock was chosen after an extensive 30 second observational period and placed in the enclosure on top of some rags to keep the internal cabinet volume the same when the cone was reversed for PP testing. The speaker with the magnet facing forward has the polarity reversed, both cones move forward when positive voltage is applied.

We had a perfect day for testing, (other than smoke from the many nearby fires, and 100 degree temperature) ambient and wind noise were very low. Testing was done at 2 meters.

Using LAB12 drivers, although second, fourth, and sixth order harmonics were greatly reduced by push-pull loading, the second harmonic sometimes increased, resulting in the THD (total harmonic distortion) not always significantly changing, as can be seen in the 20 Hz 49 volt test results .
That said, distortion figures were reduced by 50% or more at some frequencies.

Since the frequency response and output of both the PP and standard cabinets were almost identical, an A/B listening test was simple, just swap the speaker cord and short out the unused cabinet.

At lower power levels, where the LAB12 is quite clean, no difference could be detected. When pushed at a power level where distortion could be noticed, the most distracting artifact was the audible vent noise from the reversed magnet structure of the PP. The lack of the second harmonic, an octave, made the now predominant third harmonic distortion more apparent in the PP cabinet. This is a music related thing, the third harmonic, being a perfect fifth, may sound OK with some compositions, while sounding “wrong” with others.

Although the technical side of me says reduction of distortion of any sort is a good thing as far as a reproduction system is concerned, both my old ears, and a college freshman apprentice thought the push pull cabinet sounded less “musical” when pushed hard.

Listening tests were not extensive, as we had to put the speakers away due to rain, the first in months. I put the speakers back to normal, and put the grill back on. Today I realized we had not done listening tests on the sealed versions of the cabinets. Also forgot to take an amplitude response for the PP ported cabinet, but judging from the response curves of the sealed PP cabinet compared to normal, looks like the frequency response would be little different below 250 Hz. The sharp dip around 300 Hz in the “Raw 2x12” is a port resonance.

The distortion screen shots are in posts 3 & 4.

Addendum:
The Lab 12 DC resistance and cabinet minimum impedance is almost the same, 4.29 ohms per speaker, 2.145 for a pair of Lab 12s at 49 volts is about 560 (rather than 400) watts per driver, 282 (rather than 200) watts per driver in the 38.4 volt test.

Art

I have a pair of Peerless TC9FD18-08 drivers. I've tested them in a 3 L heavily stuffed closed box and they sound fantastic. The best mids/highs I've heard.
And now I want proper speakers made with them, conventional 2.0 design. I want to preserve as much of the frequency range produced by the TC9 drivers as possible while providing assistance in the low-end range.

I need a woofer/subwoofer that will work in a reasonably sized vented(or with a passive radiator) box(around 10-12 L not more than around 15 L) and play up to around 350 Hz.
Also I would like to select something that will go as low as humanly possible with a 5-6.5 inches driver and reasonably sized box.
I plan on listening my future speakers at very moderate levels, few Watts of power, not more than that. I will prefer low-end reach to a huge excursion and power handling for sure.
I will listen to them in the only sweet spot behind my desk.
2nd-order crossover will be active and the speakers will be bi-amped, so no sensitivity match required between woofer and fullrange. HP filter with high Q to assist with the bottom end and to limit the excursion can be easily added.

I'm eagerly waiting for your recommendations.

I've seen a FAST design with TC9FD18-08 and RS225-8, but that 8-incher requires a huge box that won't fit my current living space.

I’m very much enjoying a simple box with a pair of the MA SOTA drivers but now I’m looking to downsize my main system and the Tysen/FAST system piqued my interest.

The Alpair 5.3 looks like a little detail monster so that is my choice for the mid/high portion

For the bass I’ve always liked the look of the SB15SFCR39-8 from SB Acoustics (https://doc.soundimports.nl/pdf/brands/SB Acoustics/SB15SFCR39-8/SB15SFCR39-8.pdf) A pair in an opposed side firing,push push design but sealed. This might be nice as they have a lovely deep roll off for tuneful lows In a sealed box.

Am I nuts for going sealed? Will the Alpair 5.3 keep up? What sort of positioning in the room should a Tysen have with its side firing woofers? I’m used to much larger speakers 15/10/1.4CD inch drivers, but have lost WAF. I know the A5.3 is renowned for detail so I’m wondering what sort of picture will this design can paint?

Any thoughts would be greatly received.

I am in the process of updating the drivers on the ML-4C. I have redone the crossover schematic to match the crossovers documented in the ML4C service manual(also attached). The new drivers are the MDT40 and MDM55 made by Morel as recommended by Roger Russel in his restoration info attached to this thread, https://www.diyaudio.com/community/threads/restoring-mcintosh-ml-1cs.380129/. The manufacturer published 0 degree FRD/ZMA for those drivers are also attached. I also attached the SPL graph from VituixCAD for the upper/lower midrange and tweeter reponses and the VituixCAD file for this speaker system(change the extension on the ml4c_all_speakers_schematic file to ml4c_all_speakers_schematic.vxp, in order for it to load into VituixCAD). The Woofer and Midrange schematic is included but is detached from the main crossover because I do not have the FRD/ZMA for those old drivers. I am posting this info hoping someone has the frequency responses of those drivers to verify the 1.5K crossover and overall axial response. If not available and I've searched everywhere, likely I will have to measure those drivers... but being the ML-4Cs weigh more than a fridge, I'm not looking forward to that.

I had previously updated the crossover components in 2021(pandemic project) with the same original schematic values and brought life back into those speakers.

Before:


After:


I'm wanting to update the drivers so I can get some more life from these wonderful speakers.

Any comments on the crossover are welcome. Sadly, Roger Russel is no longer available to us.

The discussions around current drive amps has been going on for years, but very few are ever built. Any active speaker with dedicated amps for mid and tweeter might potentially benefit from it, and also FR drivers tends to have a huge benefit from being powered by a current drive amplifier.

In theory, a current drive amplifier is just an amplifier with infinite output impedance. A voltage drive amplifier, on the other hand, is an amplifier with zero output impedance. As all speakers generate their force from current, and not from voltage, having the speaker fed by a controlled voltage is in many senses a step away from controling the driver directly. This is not suitable for all speakers, certainly not if you have 100% current drive, but for some situations, a current drive amp just might be the right choice.

One of the most obvious situations where a current drive power amplifier should be considered is for midrange and tweeter compression driver/horn-combinations. This is sort of the basic idea behind this project, so one of the main focus points is low noise and low distortion. High gain and high power however, is not a priority.

To achieve this, the idea is to stack many small signal op-amps in parallell on each output. By manipulating the balance of the circuit, the level of current drive (or output impedance if you will), the amp is adjustable between current drive and voltage drive. At most, it should be pretty much 100% current drive, and at the other end of the scale, it should be close to 100% voltage drive.

Other priorities are noise (less than 10µV unweighted) and, of course, very low distortion. We are looking at adding local voltage regulators for each op-amp to better achieve this. We are probably looking at upwards to 80W/8 ohm and 160W/4 ohm, but as a current drive amplifier does not increase the power when the impedance is reduced, these numbers are slightly theoretical.

Is this something you guys find interesting? Should I keep you updated on this?



EDIT: And before you post your opinion on why voltage drive is better for a complete loudspeaker. Yes, that is why current drive is only used successfully in active systems, and especially for mid and tweeter, (above Fs) which is also the aim for this project.

I have 2 of these dated 26.01.2023 that have been sitting on the bench due to changed amp plans.

€30 each plus shipping from Sweden.

Light domestic use and never above 35C, specced at 19,000h @ 85C and have been on the bench for the last 15 years so plenty of life left.
https://www.mouser.se/datasheet/2/212/KEM_A4034_PEH200-1101128.pdf
€40 for both plus shipping.

Can’t find the orignal Stereo Review April cover but it looks like someone actually made a LIRPA-style record player.



https://www.cultofmac.com/829200/rokblok-wireless-portable-record-player/#google_vignette

https://deals.cultofmac.com/sales/r...7745&utm_content=a0x1P000005OuoTQAS&scsonar=1

https://www.soundandvision.com/content/history-lirpa-labs

dave

SOLD


This is a completed RaspberryPi based streamer with top of the line parts from Ian Canada. It is loaded with Ropieee software but could be changed out to a different software. Some DIY knowledge would be needed to manage that and set it up on a new network. A great sounding unit that really made me realize the difference a streamer could make in the sound quality of a system. So why am I selling it then? I'm going to move up to a significantly more expensive streamer in hopes of further refining my system.

Price is $450 including shipping CONUS only and payment via PayPal friends and family option.

This is significantly less than the cost of all the components that went into the streamer. I have those parts listed out below with associated new costs. I am not looking to sell individual components and will only sell as a package

Pair of Output Transformers for Push-Pull Amp. Approximate values are 1600-1700Pri Impedance to 4, 8 and 16ohm secondary. As you can see in the images, there is also what looks to be a second output winding with the green, green/yellow stripe and brown/white striped wires. I am not sure what it could be used for. Transformers are heavy at app 7.5lbs each. Wires have never been soldered. $150obo plus $40 shipping in continental United States.

I’ve been rebuilding a few tube radios that I own. I realize that our line voltage is a bit higher than it was back in the day, so I am installing a thermistor on each of them to bring it down a few volts and I’m even open to adding a large resistor right before the primary winding to bring it down a few more.

I know that many of the capacitors from back in the day had both their working voltage and a peak voltage stamped on the can. I replaced the caps in this particular radio were rated for 400v and 450v. I replaced them all with 450v. I measured them on power up and the voltage shots up to 480-490v on all three caps and then settle at about 380v on the original 450v cap and 350v on the two caps what were 400v rated caps. So that means the two 400v caps were seeing nearly 20-25% higher than rated voltage, granted only for a few seconds. These originals don’t have a peak voltage printed on them.

I looked on the spec sheet of my replacements and couldn’t find anything on peak voltage. I’m using Nichicon CA, and another very good quality Nichicon along with good quality Panasonic, all 105 c of course. I haven’t run into an issue yet, but I was just curious as to how high these newer caps can go. If I were to swap the 400v rated caps with 400v rated, could the new 400v caps see that 480-490v for that several second duration like the vintage caps could?

Dan

I was the fortunate winner of the Sony VFET essentials kit auctioned yesterday at BAF22. So, naturally, I immediately contacted Gianluca of Modushop to beg for a chassis - like the gorgeous limited run done for the lottery. Gianluca amazed me by replying at what must have been the closing time of the bar opposite Burning Amp - in the wee, small hours…

Gianluca, who I hope will see this and confirm the following, said he would be prepared to do a small production run for a minimum of ten chassis. He suggested we start a thread and that is what this is - a list of interested parties prepared to commit to buying one or more VFET chassis from Gianluca. I am not offering to head up a Group Buy but simply hoping we can get to ten or more chassis orders here and then contact Gianluca with orders.

Name / Number of chassis wanted

derekr 3

Hi All,

Looking to build a nice set of 3 way floor standers.
I have a large room, approx 50-60m2, so looking for a decent size speaker to cover it.
Will be running a Denon X3800h (or extra amp if required when going passive)

I have been doing heaps of research to find a design, but i'd get stumped with massive freight costs, or unable to buy the driver etc.

So I have decided I'd like to build a 3 way, SB accoustics build, mainly because I can easily source the drivers in Australia.

I have tossed up the idea of active vs passive, was thinking maybe a couple of Hypex amps. So i could do a bit of dsp etc, if required.

I had nearly decided on a set of Zaph 12.3, but I'm undecided, thought i would ask some advice before deciding.
The physical size here is no worries.

So my decision basically comes down to active vs passive (1.5-2k worth of hypex amps before i even start the build) vs designing/testing crossovers and buying an amp if needed.
I don't mind either way honestly.

Then it just comes down to drivers. I do like the idea of having the 12" low end, 6-7" mid and tweeter.
I've seen a few designs that have the likes of, SB29RDNC, SB17NRX, SB34 variants.
If i went passive and crossovers costs didnt get out of control, i could probably stretch the driver budget a bit higher. EG. Satori midwoofer, TW29R tweeter

Going passive will require me to ask a lot more questions on here as its been years since i have dabbled with speaker building.
I've got a Umik-1 & DATS V2. Happy to learn whatever programs needed to do sims.
I've got plenty of access to panel saws, CNC routers etc, so i'm all good for the woodworking side of things.

Where should i go from here?

If you were in the same boat, what would you build?

Thanks so much in advanced!

I'm designing a compressor and everything is quite clear to me, apart from one thing relating to the attack time:
a thought to which I cannot find an answer, as the opposite condition is generally assumed: attack time shorter than the threshold trigger period
What happens if the input signal goes below the threshold before the attack time is over? Will it reset compressor starting the release curve or will the reduction (compression) continue to rise until the attack time is completed even if the threshold is no longer triggered and then goes into the release curve?
Thank you!

Hello everyone. I've been digging on Youtube and found a Mr. who designs, builds and measures other builders' speakers.
I see that he performs measurements of different well-known brands of speakers, finding defects in their frequency response and in turn making modifications in order to improve them.
I see brands like KEF; B&W; Klipsch; paradigm; Focus Chorus; Etc finds them poorly designed. This is so?. The big manufacturers do this on purpose? Is it good or bad to get a speaker to have a flat frequency response?
I have a B&W DM602, and although I find it too analytical and a bit bright, I don't see it as a bad thing, on the contrary, I like it.
Greetings to all.
https://www.youtube.com/@GRResearch/videos

I am looking for information or photos for the correct positioning of the rotary switch of the Tektronix DMM912 multimeter
I'm also looking for the wiring diagram.

Hey guys,

I'll start with a little background. I'm a helicopter pilot by trade and one of my day to day jobs is flying digital surveying flights. Essentially flying a grid pattern over specified areas for up to 8 hours at a time. I adore my job, but there is no doubt it gets a little tedious without some tunes or an audiobook to focus on. Recently I dropped some considerable cash on an in-line Bluetooth adapter for my helmet. However, the audio quality is dismal. Well suited to phone calls, but that's about it.

I've decided to try and build my own Bluetooth receiver. I've been experimenting with an ESP-32 and an I2S DAC acting as the audio source. This is working well. However, I'm a little bit stumped on how to feed my amplified music into my headset without backfeeding the helicopters intercom system.

The basic requirement is theoretically simple I think: I need to overlay my amplified music on top of the amplified signal from the helicopter without cross talk. Additionally The helicopter audio needs to pass through even if my Bluetooth system is not powered.

I'm not entirely sure how to approach this problem.

I figure I have two options: I can mix the two signals, or I can switch between the two signals.

I think mixing is the more technically correct solution. If something goes wrong with my hardware it's less likely to mute the helicopters intercom system. But switching between the amplified sources may be the more robust solution, however it would have to be carefully designed to automatically switch back to the helicopters audio when it detects audio on the intercom or if the Bluetooth battery dies.

Anyway, I'll cut to the point:

I have two amplifiers and one headset. What is the best for me to connect both amplifiers to the single headset without damaging anything? Is it better to switch back and forth, or is it possible to mix both amplified sources? What ICs or circuitry should I be looking at?

Thanks a ton for letting me pick your brains, guys. I really appreciate it!

I have two microwave transformers for 230v mains. they are gaped to support DC

could one be used as output transforemr for SE triode amp ?
230v secondary is maybe good for 16ohm speaker?

I was hoping someone could explain how to hook up this amplifier Pioneer GM-H120...I was reading an old thread and apparently this amp has something called a floating circuit. You have to ground the "shields" but I don't know what SHIELDS mean???