True Wireless Stereo (TWS) Bluetooth for Speakers

Hi Folks,
I am looking for a way to have two physically separated wirelss Bluetooth speakers play stereo. I do not want a wire connection between the left and the right and I want it to connect like a single BT device. I know that this is possible as I have several earbuds and headphones that do this. They ususally call this TWS (true wireless stereo) and I have searched and searched but have failed to find either a line level TWS receiver pair or a simple Class D amp pair with TWS. I know that if I hacked into the wireless earbuds, I could indeed take the headphone outputs and connect them each to a power amp and make my own TWS amplifier. But that seems silly. Surely, there must be a commercial off the shelf solution for this already?

The idea here is to have a stereo BT speaker set, physically placed in a room. I do not want clutter from a wire running from the left to the right one.

I do not need a lot of power. 5W or 15W woud be enough.

Hello i have been lurking on here for a while, but finally decided to make an account. i am a avid DIYer on all aspects.
Looking to build some gear to save some money and add to my Pro Audio stash.

I am currently building my Soundsystem for Dub/Reggae/Jungle and I am looking to be inspired for the best possible enclosure designs suiting my needs.
I hope to find some helping hands on this very new journey for me.

Thanks for having me.

First of all I have to mention that this thread started following Mark’s idea found in this thread https://www.diyaudio.com/community/...apacitors-smd-assembly-max-3a-max-48v.405099/
I needed clean power for a vfet follower amplifier that was getting its juice from a 90w laptop brick followed by a sk80h buck boost converter. Because there was also low frequency noise beside the high frequency one I decided to add the cap multiplier inspired too by an earlier design from same Mark.
So practically the only thing I did was to play around a bit in my pcb design software to put together the pcbs.
It all started here https://www.diyaudio.com/community/...d-assembly-max-3a-max-48v.405099/post-7505998

And then after that this part followed..

A few users asked by private messaging about the single rail pcb but also about a dual rail or bipolar pcb. At the time I had only the single rail pcb so I drew the bipolar version. I call it bipolar because how it`s designed but it can be use as a dual too.

For the bipolar version I created 2 pcbs. One that has a single ground plane for both rails and another that has the two ground planes separated. Initially I done the single ground pcb and then asking Mark for a suggestion I got the dual ground pcb.
On the dual gnd pcb you have the possibility to connect the gnds at the input or at the output of the filter.
For each pcb I will attach the schematic, bom, a few photos of how it looks and the gerbers.

I was planning to release these gerbers in a week or two after testing my single rail unit(I don`t intend to build and test the dual/bipolar pcbs) but then realized that it will be a bit late for those who want to have something to solder in the holidays period.

The dual pcb can be used as both positive, positive and negative or both negative filters.
The lower half of the pcb is designed for a negative filter but if you reverse the electrolytic caps and instead of the pnp bjts you place the npn ones as on the positive rail you can make the bottom part a positive filter so you will have 2 positive filters on same pcb.
If you need two negative filters on same pcb you will need to reverse all electrolytic caps on the upper half and instead of the npn bjts place pnp ones. Simple as that.

Edit1: all the boms miss the heatsink that is needed on the bd139/bd140 devices. After I build the single version I will edit all the boms with the needed part.
Edit2: after testing the single rail pcb I found that there is no need for a heatsink for the bd139/140 devices so nothing to add to the boms. Same thing is valid for the bipolar version too.

As shown here: https://www.diyaudio.com/community/threads/tanka-se-and-balanced-preamps-presentation.428346/

Tanka SE and Tanka kits

Both kits are comprised:

• Motherboard with all SMD work done
• TFT display/logic module fully assembled
• small pcb for SSRelay/connection of mains Donut's primaries
• Fancy remote (CR2032 battery you need to buy, can't send battery in package)
• assembled flat cables
• pcb IDC connectors
• encoder assembled (pcb, cable)
• protection perspex screen for display
• all necessary CAD files for front and back plate, sent by e-mail ...... Modushop already did several Iron Pumpkin cases, practically same job
• pack of schematic and graphic files, also sent by e-mail
• all resistors (metal film 0207 size), including NTCs
• all solid caps
• all electrolytic caps
• all heatsinks (in case of balanced, two additional custom Al plates serving as big hsnks; compromise, but best one)
• all necessary isolators ( mica, plastic bushings)
• all diodes and diode bridges
• all active parts - semis, ICs
• tube sockets
• jumper pins and jumpers
• all Fujitsu micro relays
• 30VA mains Logic/Heating Donut, custom made; static shield, magnetic shield, primary for your neck of Wood; regular fixing hardware included
• 30VA mains LoVoltage Donut, custom made; static shield, magnetic shield, separate secondaries for each channel, primary for your neck of Wood; regular fixing hardware included
• 20VA mains HiVoltage Donut, custom made; static shield, magnetic shield, separate secondaries for each channel, primary for your neck of Wood; regular fixing hardware included

**************************
WHAT YOU DON'T GET IN KIT:

- small screws, nuts and washers; you're Diyer, having them all

- Cinemag/Jensen/Edcor repeater xformers; it doesn't matter where you live, it matters where I live; if you're in Europe, take them from Don Audio... if not, take them directly from manuacturer - either way is cheaper than Mighty ZM importing them, then sending them abroad.

- Tubes; in general, each Tube Aficionado is passionate about his Toobz, so best to use what you have stashed; though, if you insist, I can manage Russkie (6J9P/6Ж9П for SE and 6N23P/6Н23П for Balanced) and I'm expecting their cost in range of 20E/pair; tested in Tube tester but also in my own preamp ..... best way to know they're perfect
******************************


Kit prices (all in Euro - €)............. first take a look at available pictures and graphical files, then on list, and just then look at numbers

SE Kit - 850€

Bal kit - 950€

That includes shipping wherever you live, but not Paypal fee; if Paypal fee (around 30€) is too much for your stomack, possible payment to my Biz Bank Account, usually it costs less.

Shipping time frame mostly dependant of custom Donuts production; they usually deliver in two weeks time.... so there it is.


Finished preamp prices (Modushop 2U/350 case, Neutrik connectors, front black or silver, mains voltage according to your needs):

-SE - 2350€
-Bal - 2450€

........plus legal export/shipping worldwide (100€ is covering that); Shipping goes through "Post Export" service, declared value of 500€, to save you of bigger Custom expenses

Well here's some info on my newest project. (Skhorn is pronounced like the word scorn.)

In short this's something I've been working on for years to replace my Othorn cabs. The design goals going in were pretty much the same. PA or very high level music playback in large or outdoor spaces. The main areas that I wanted to improve over the Othorn are as below.

#1 Cut down on cabinet and panel vibration near the driver.
#2 Improve the fold or reduce build complexity.
#3 Higher overall performance.
#4 More driver options and some less expensive ones.
#5 Increase the “FUN” factor even further

After simulations of what seemed like every cab type and most of the commonly available drivers, I ended up ditching the 8th order BP I had, which looked really good on paper, but was an absolute nightmare to turn from a sim into a buildable cab. Not to mention the extreme sensitivity to mistuning, etc... After that a TH was going to be the follow up and I had it all drawn up but I just wasn't satisfied with it as it seemed like an incremental step rather than something new. Finally I settled on the cab type also used on the M.A.U.L.. It was basically a parallel effort on both designs. The big one just happened to get built and tested first.

The Skhorn is a 24x32x54" cab that is comparable in size to the low tuned dual 18 vented cabs on the market. It's 24cu ft or 680L external volume. Originally I wanted to keep the size the same as the Othorn which is 18cu ft external but using 2 large drivers simply required a bit more volume and a different shape. The Skhorn is exactly 33.33% bigger than the Othorn, so 3 Skhorn are the same volume of space as 4 Othorn cabs.

I settled on a quasi 6th order BP, where the low end is vented and the upper end of the loading is a short, expanding slot/horn, with an opposed pair of 15-21" drivers, in an OD arrangement. I ended up at this while trying to work on translating a standard 6th order sim into wood and screws. I was having trouble getting the upper bass vents to fit into the cabinet and this caused me to look at how a straight slot performed instead since it is MUCH simpler to fit into the cab design. From there it was natural to model the slot with both a positive and negative taper and see what happened. A positive flare seemed to offer some improvements over a simple vent and with tweaking of the length, area and expansion, I found that this type of loading for the drivers could produce a smooth response over a wide bandwidth while also exhibiting some gains over a standard vented system using the same driver.

EDIT: 02/20/18
I have improved the accuracy of HR simulation inputs when compared to the measured ground-plane performance of the final speaker. The HR inputs below are not nearly as accurate as those developed after testing the final cab.

Here’s the cab design.

I'm trying to repair the Class D amp out of an Acoustic Research powered subwoofer which I'd managed to get running again but had a mishap with a scope probe that blew my isolation transformer's fuse and may have damaged some parts in the process. I have managed to identify one of the NPN and one of the PNP final transistors as having failed short (IOW, ~266VDC in communication with each other @_@):


When I first got this in to repair last year, one of those transistors had already gone and I sourced and installed a replacement, but this break/fix go-round the replacement was one of the shorted ones. It looks like reliable sources of the original models (2SC3281 and 2SA1302) can't be had anymore but the intertubes are telling me that I can substitute 2SC5200N and 2SA1943N and I've ordered three of each. I've seen posts about output transistor matching in Class D amps but I need to be clear on something: what is more important to match, Q13 to Q14 and Q17 to Q16 or all four to each other? I've got one of those inexpensive universal testers with the little color LCD screen that will kick out Hfe and a couple of other numbers; will that be sufficient to help me find the closest matches?

I have only studied tube amplifiers, but I am interested in transistor amplifiers this time, and I want to study them. The problem is that I know nothing about transistors. I want to buy a kit for under $50 from AliExpress and make it as a beginner. Currently, I am looking at the TDA7293 kit and the Quad405 kit. Which one sounds sweeter? Or is there a kit that you recommend for under $50?

Can i get both sq and spl if i go dual 12" sealed 500w vs one one 12" ported 1000w?
I like the ported rumble.
With 2 sealed i will gain more midbass, but can i rescue the rumble? I dont want to go 2 ported because then i loose the sq, plus needs a bigger box.
Car audio
Qts of the subs is 0.3

Hey all,
I’m seeking help to design a pair of front loaded horn cabinets. These cabinets will be seating a 12mh36 B&C paired with a HLCD (2445j) all controlled via DSP. I’m hoping to see a freq response from approx 250hz-1khz. (ideally would like it to go lower ~150hz but may not be applicable as it would need to be longer, from my knowledge, needs to be around 10" depth for my needs). I’m pretty new to using hornresp so i don’t know if there’s a given rule to input parameters such as s1,s2 nor actually getting the horn flare measurements for cutouts etc. I want to design a horn that starts conical and goes exponential, (see picture) open to other designs as well maybe tractrix and such. Im trying to make this as compact as can be as it would be toted in car and used. If anyone can help me even get started I’d appreciate it!

ANK L3 Phono amp. Assembled and complete minus the 2 power supply tubes. ECL82 and 6X5. I am including a 6DJ8 and a 12AX7. I added up the price for the parts just the big parts are as follows:
272BX Trafo - 105
Choke - 67
Triad trafo - 20
Big white Mundorf EVO cap - 77
Small EVO caps - 35 each *2
Audio Note caps - 58 each *2
Rel Caps - 24 total

Just those parts alone are like $470. Also all parts came from either Parts Connexion or Mouser. The circuit boards are not ANK brand boards but they are well made. This unit works great and is silent as they come. I lost the power supply tubes or I would include them. I have a moving coil cartridge and this did not have enough gain for it. It is in tested but unused condition. I am asking $300 you pay shipping. I live in Corvallis Oregon in case anyone is local. I used all Cardas solder. The wires on the boards between the sockets are supposed to be there. Its not a "fixit".

As shown here: https://www.diyaudio.com/community/threads/irreverent-se-and-balanced-preamps-presentation.428339/


Irreverent SE and Irreverent kits

Both kits are comprised:

• Motherboard with all SMD work done
• TFT display/logic module fully assembled
• Fancy remote (CR2032 battery you need to buy, can't send battery in package)
• assembled flat cables
• pcb IDC connectors
• encoder assembled (pcb, cable)
• protection perspex screen for display
• all necessary CAD files for front and back plate, sent by e-mail ...... Modushop already did several Iron Pumpkin cases, practically same job
• pack of schematic and graphic files, also sent by e-mail
• all resistors (metal film 0207 size), including NTCs
• all solid caps
• all electrolytic caps
• all heatsinks
• all necessary isolators ( mica, plastic bushings)
• all diodes and diode bridges
• all active parts - semis, ICs
• jumper pins and jumpers
• all Fujitsu micro relays
• 10VA mains Logic Donut, custom made; static shield, magnetic shield, primary for your neck of Wood; regular fixing hardware included
• 20VA mains Audio Donut, custom made; static shield, magnetic shield, separate secondaries for each channel, primary for your neck of Wood; regular fixing hardware included

**************************
WHAT YOU DON'T GET IN KIT:

- small screws, nuts and washers; you're Diyer, having them all

- Cinemag/Jensen/Edcor repeater xformers; it doesn't matter where you live, it matters where I live; if you're in Europe, take them from Don Audio... if not, take them directly from manuacturer - either way is cheaper than Mighty ZM importing them, then sending them abroad.

******************************


Kit prices (all in Euro - €) ............. first take a look at available pictures and graphical files, then on list, and just then look at numbers

SE Kit - 700€

Bal kit - 800€

That includes shipping wherever you live, but not Paypal fee; if Paypal fee (starting with 30€) is too much for your stomack, possible payment to my Biz Bank Account, usually it costs less; Wise service is cheap and handy.

Shipping time frame mostly depends of custom Donuts production; they usually deliver in two weeks time.... so there it is.


Finished preamp prices (Modushop 2U/280 case, Neutrik connectors, front black or silver, mains voltage according to your needs):

-SE - 2300€
-Bal - 2400€

........plus legal export/shipping worldwide (100€ is covering that); Shipping goes through "Post Export" service, declared value of 500€, to save you of bigger Custom expenses

What is the difference in the end between say using a DN2540 style CCS at the anode vs a LM317 CCS at the cathode? Isn't the end-game objective the same to fix the DC current? Does the anode CCS also provide a higher impedance load benefit, whereby the cathode CCS would only fix the current but not ease the load? What if my driver stage currently uses an interstage transformer load, could adding a CCS above anode choke really improve things beyond a choke alone? Basically if you had a driver stage that had a interstage anode and cathode resistor. And you wanted to add a CCS, would you add it at the cathode or anode?

For sale... my old Ittok tonearm.. It's black, comes with the tonearm subchassis, etc. it's in excellent shape, everything about works perfect. No scratches. Very well taken care of over the years.

Black. It's a rare color for the Ittok. It does look very nice.

Reason for sale: Upgraded tonearm and sub chassis.

$1100 OBO.

I'll post pictures if you're interested.

Tim Stinson here. Owner of Luminous Audio. Just hoping to share ideas and perhaps obtain some knowledge from others on designs repairs.

I have a total of 10 pieces, 5 each of GE and Sylvania NOS triodes in their original cartons. Manufacture date ca. 1984-85.

$7 each plus shipping.

PM me if interested.

Thread Index
Please go to posts #2500-2502 see the latest version of this project.
There you will find the current baffle plans and crossover schematics.
For explanations of how the crossover works, see post #1388
https://www.diyaudio.com/community/threads/fast-fun-inexpensive-ob-project.110583/post-4573958
For ideas on doing an active crossover see post #3006
https://www.diyaudio.com/community/threads/fast-fun-inexpensive-ob-project.110583/post-7033913

---

100Some time ago last year a speaker building buddy of mine in California decided to see what he could do in a simple, inexpensive, open baffle project. He came up with a 2 way passive system on a medium size baffle. He has been trotting them out at shows across the country and baffling a lot of folks who would never have thought so simple a concept could sound so good.

For your pleasure, here are the build specs on the Manzanita 12s:
To build each speaker you will need:

• Peerless SLS 830669 - 12" Woofer
• Seas 27TDFC tweeter
• Sledgehammer 12mH 15 gauge inductor
• 0.8 mH aircore inductor
• 12uF film capacitor
• 25 ohm 5W resistor
• Binding posts
• 3/4 wood for baffle, base and side wings. MDF or plywood, chipboard, etc.

Total project parts cost is under $150 US per side, excluding wood. Or less than $300 for the pair. The drivers and parts are easy to find in the US, and should be as easy to find in Europe. As long as you keep the crossover values the same, feel free to substitute your favorite brands. Obviously, you will use the same drivers!

There may be plenty of forum denizens who will poke holes in this design without ever building it. No worries, that’s part of the DIY sport. Those who do build it will enjoy it, holes or not.

Why build this speaker? A few reasons:

1. It sounds good.
2. It’s simple and easy to build.
3. It plays well in an average size living room.
4. It does not cost arm and a leg.
5. Works well with most types of music.
6. Very wide and deep soundstage.
7. Easy to listen to – low fatigue.
8. You’ve always wanted to try an open baffle design.

Why NOT build this speaker?

1. Too simple. You need more of a challenge.
2. Too cheap, you need to impress your friends.
3. You like a hot midrange.
4. You need ultimate finesse and flattest response.
5. Your listening room is huge – or tiny.
6. Your amp is a 2 watt SET-DHT job.
7. You would rather go to the beach. (I understand…)

Really, this project is so easy you can start after lunch and be finished in time to kick back, and enjoy the blues and some brews before dinner. The speakers throw a large soundstage, don’t suffer typical box coloration and have good tonal balance. The recessed midrange makes them very easy to listen to. But the midrange fills in nicely in the typical living room that is often a little over bright. With a good solid state or tube amp of 20 watts or more, you’ll have plenty of power. Even an AMP6 10 watt T-Amp runs these speakers to quite respectable volumes. A 20 watt tube amps has no trouble, despite the low sensitivity.


Continued in next post.....

Greetings.

I present the DIY FRONT END 2022.




EDIT: For current boards marked "V0R1" please find the changes and additional information in post #686 of this thread
https://www.diyaudio.com/community/threads/diy-front-end-2022.394339/page-35#post-7323986

Hi , is it a bad ideea to twist speaker wires ? If using two separate wires for + and - , for esthetic purposes. I'm thinking it will increase capacitance , inductance . ?
- Bruno.

The audiophile community has given these opamps great reviews, and I was wondering if anyone here has ever tried them:
MUSES01 NJR | MUSES01-ND | DigiKey

The datasheet specs look similar to every other opamp. I'm curious what all the hype is about.

Hello all diyer's !

I'm offering a thread that brings together videos of our stereo systems via YouTube or Dailymotion so you can listen to and watch our beloved creations, whether in the field of electro-acoustics or electronics, amplifiers, sources, speakers, and show us the small, characteristic details.

Enjoy watching!
Laurent

Login to view embedded media

I don't know if this is a simple question or not, but...

In a classic tube guitar amp like a Fender Deluxe Reverb or Twin Reverb, when you dial in a 'clean' sound at moderate old-style country music or jazz combo volume, about what level of THD is there in the signal from the amplifier (not including the speaker here)?

1% THD?
3% THD?
5% THD?
10% THD?
More?

I'm playing around with designing a guitar preamp with pre-gain and post-gain controls. With the pre-gain down at '1' or '2', I'm wondering what level of harmonic distortion should be in the output signal at that point. I figure at least 3%, 2nd and 3rd harmonics dominating, but I don't actually know.

Anyone?

Hi everyone. Thanks for letting me join.

got hold of a rotel power amp
the mains transformer has gone short circuit 2x 40v 0 40v
blown 5x 2SB817 2x 2SD1074 2x 2SB631K
what i would like to know is there an equivalent to the 2SB631K please see pic for the schematic
also the caps highlighted in schematic c609 & c606 should they be low esr or standard
c606 it only shows 1 on schematic but the pcb's are both populated with the caps
has anyone got a transformer or 2 that i could stack to replace the original UK ONLY
Regards Glenn

So this isn't (for a change) an assault for the ultimate reproduction quality (all mine failed so far 🙂) but I hope for maybe at least one or two extraordinary sound properties and a look that befits a small but cool penthouse flat.

It will try to be as much of a point source as possible but has no prospect of having a truly flat, linear, directivity - it wont. The aim is for it to be really high resolving and low distorsion (if not pushed) - SPL to reach 70/90 dB (crest/peak).

Due to space constraints it need to occupy little floor space and rest close to wall. Most often only one person will consume music via the Hornflowers.

At the time for this post, I'm half way the build. The complete receipt looks like:

Hornflower (per side)

• ST260-30 waveguide by member mabat and his ATH software (printed by JLCPCB)
• 18sounds NSD1095N 16ohm CD + 16 ohm resistor for 32 ohm total
• 4 pcs of SB12PAC25-4
• 20cm dia paper tubes for casting house foundation pillars
• flooring boards 8mm
• metal picture frames
• bookshelf hangers
• glue, concrete-clay, paint etc
• Active XO (1600?) DSP EQ

Electronics

• Squeezbox Touch
• Mac mini
• CamillaDSP
• RME Digiface toslink
• 2pcs smsl SU-6
• Anaview str-ams0100-2300 (Topping L30 (HF) was abandoned after a couple of months)
• (3 pairs in parallel out of four from a cat6 cable for 30 ohm char imp. for HF. - not used)
• Aiyima A07 TPA3255 / SMPS300R 38V (LF)
• Some whatever cable for LF 🙂

Placing

• On wall

I'll continue with pictures of the build and with measurements as they happen.



Below: Radiation principle and how the point source is obtained. Delay of HF is needed.






//

The record player "Alamo" from Moth is a good known record player (nearly identical to Rega Planar and NAD's 533.
But I have an other model from Moth. Typ: "Kanoot" Unfortunately there isn't similar type from other companies.

The actually device in correct working condition has on problem: the motor pulley's sizes (for belt) is made for the British marked (mains frequency 60 Hz instead 50 Hz).
Therefore in Germany the RPM value isn't right.

Where I get such motor pulley for 50 Hz (to replace the exist 60 Hz version)?
Motor model is follow: SAJA MURTEN UDR11UJ1RNZ32 (SWITZERLAND) - go to second image from post #13, also used in Revolver turntables and some other.

I have now realized another solution to avoid having to laboriously remove the 60Hz pulley and replace it with a 50Hz version.

I remove the capacitors at the motor and introduce this motor control unit (clone from Dr. Fuß) - often incorrectly referred to as a power supply :
Homebrew Motor Control Linn LP12 - Circuit Description wanted for Sine Wave Osc.
To the resistors R28 and R27 I add a 27K resistor in parallel (have a look in the PDF schematic of post #16).

This works perfect together with the 60Hz pulley. The target speed is now (only at 33) a bit right of the middle position of the speed controller knob.

The old address from Moth is follow:
Moth Group
Tel: 01234 741152
10, Dane Lane, Wilstead, Bedford, Bedfordshire MK45 3HT
and the related URLs here with some history of the Moth Group:
British Audio Products Online - About Us
British Audio Products Online - About Us

I took this unit in trade 10+ years ago. I have not done anything to it. I have no time nor the patience to fix it myself.

It is fitted with high gain Phono Module.

As can be seen it’s a bit scratched, and missing three knobs. I have, however, knobs from a Precision Fidelity preamp. Those fits as can be seen on the left side.

It also comes with one Madrigal phono cable. Camac one end and phono in the other end.

I have complete schematics on PDF.

I would like $1500, but are open to offers.

Shipping at cost.

R

What are your thoughts? I've thought some of my Kalrson boxes have launched some sort of shock wave but perhaps "not"

.








Hi Dear Brainy Bass Buddy - I want yours opinion on whether a PA "kick bin" high-tuned bandpass speaker with a front chamber could with a circular aperture and smoothed inner and outer transition could not only be a speaker but its output would under drum kicks, generate shock-wave vortex rings which would add some directional impact to its sound-field ?






Qwen3-235B-A22B

Hey there, fellow bass explorer! 🐟✨
Thanks for the brain-tickling question — this is one of those rare, beautiful intersections between audio engineering, acoustics, and fluid dynamics. You're essentially asking: Could a high-tuned bandpass subwoofer enclosure (aka "kick bin") be designed to not only reproduce low-frequency energy but also generate vortex rings during intense transients like drum kicks, thereby enhancing directional impact?


Let’s break it down with some science, imagination, and a little bit of fun.

---

🔊 What is a Kick Bin?​

A kick bin is typically a small, high-efficiency, high-tuned bandpass subwoofer enclosure optimized for tight, punchy low-end reproduction — especially useful in live sound or where powerful, articulate kick drum emulation is needed. It's sealed or ported in such a way that it emphasizes the 50–100 Hz range with fast transient response.

---

💥 Vortex Rings: What Are They?​

A vortex ring is a toroidal (donut-shaped) mass of air that spins around its axis as it moves forward. You've seen them in smoke rings, dolphin bubble rings, or even from volcanic eruptions. In air, they can carry momentum and energy over distance in a surprisingly coherent form.


They form when a puff of air is forced through a circular orifice, especially if the edges are smooth and the transition into/out of the orifice is aerodynamically favorable.

---

🎯 Your Idea: Could a Kick Bin Generate Vortex Rings?​

Yes, potentially — but under specific conditions .


Here’s what would need to happen:

1.​

• A drum kick or sub-bass transient causes rapid movement of the woofer cone.
• This creates a sudden pressure differential inside the enclosure.
• If the front chamber ends in a circular aperture , especially with rounded or flared edges , a pulse of air could be expelled in a way that forms a vortex ring.

2.​

• The vortex ring requires a short, sharp burst of air — just like snapping your fingers to make a smoke ring.
• A typical woofer doesn’t move enough air fast enough in the right direction to do this naturally. But with:
  • A high excursion driver
  • A tightly tuned bandpass that focuses energy in a narrow frequency band
  • A chambered design that channels the airflow through a nozzle-like aperture

...then you might just get a coherent vortex ring forming on each major transient.

3.​

• Smooth inner and outer transitions (like in a horn or bellmouth) reduce turbulence and help maintain laminar flow.
• These features are key for vortex formation.

---

🧪 Real-World Analogues?​

There are actually devices called air vortex cannons used in physics demos and even HVAC systems that use similar principles. Some people have experimented with using subwoofers to launch vortex rings by coupling them to chambers with nozzles.

• For example: DIY Vortex Cannons often use speaker cones driven by signals to generate puffs of air.
• So yes — a woofer can generate vortex rings , especially if the system is tuned for short, powerful bursts of air.

---

📣 Does This Enhance the Sound Field?​

Potentially!

• Directional Impact : Vortex rings carry momentum and can push air further in a focused direction than regular sound waves. This could give the illusion of more "punch" or "hit" — especially in open-air environments.
• Tactile Feedback : The moving air could enhance the physical sensation of bass, beyond what the eardrum perceives.
• Psychoacoustic Effect : Our brains interpret both auditory and tactile inputs together. Feeling a puff of air timed with a kick drum may enhance the perception of loudness and presence.

---

🧠 Caveats & Considerations​

• Efficiency Loss : Channeling air through an aperture will likely reduce acoustic efficiency unless carefully engineered.
• Frequency Range : Vortex generation works best with short pulses — so ultra-low frequencies (say below 40Hz) may not benefit much.
• Design Precision : Getting the geometry right (chamber size, port diameter, flare angles) is crucial. Too big, and the vortex won't form; too small, and it dissipates quickly.
• Phase Alignment : The timing of the vortex needs to align with the acoustic wavefront, or it might create weird interference.

---

🛠️ Suggested Experiment (for the DIYer)​

1. Build or modify a kick bin with:
   • A flared circular output port (like a trumpet bell shape)
   • A sealed front chamber with a short path to the port
   • Use a high-excursion woofer and high-pass it at ~60–80Hz
2. Test with a sharp kick signal and hold your hand near the port — do you feel a puff?
3. Add fog/smoke and a laser grid to visualize any vortex rings.

---

🎶 Final Thoughts​

Your idea is not only plausible but exciting . A well-designed kick bin could produce vortex rings during sharp transients, which would add a directional, physical component to the bass experience. It blurs the line between sound and wind , opening up new possibilities in immersive audio design, live performance, and haptic feedback.


So go ahead — build that vortex-launching kick bin! 🌪️🔊


And if you do, I want to hear about it — or better yet, see the smoke test videos! 😄


Let me know if you want help designing the enclosure or simulating the airflow — happy to dive deeper!

In an old active three way loudspeaker of a friend one of the TDA7294 has firmly blown a hole in itself. No apparent cause. After cleaning the board from black dust, the surrounding standard components on the standard pcb layout measure fine. The mute is not used. The loudspeaker unit of this mid channel measures ok.

After replacing the TDA7294, an offset of 0,4Vdc appears (input shorted). It can be traced back to the IN- by measuring the voltage at that input in relation to ground.
Without power supply R3 = 22k measures fine.
The other two TDA7294 on the pcb of this loudspeaker measure fine, hardly any offset at the output.
The voltages of the power supply are a stable + / - 25Vdc. The scope shows no sign of oscillation.

What may cause the offset of 0.4V ?

Hey Guys

I thought id post this to keep a journal of my first Amplifier Upgrade / Repair, I have inherited my fathers HCA3500 and other audio equiptment a couple of years ago.

These mods have been on the mind for over 5 yrs and i always promised my dad i would attempt them for him, unfortunately he has passed and now found time to get started
More info has come available since i first looked into this many years ago, and noticed a few threads on here

The amplifier ran fine but started having trouble with the right channel, which would take about 10 mins to kick in, (possible faulty capacitor)

I have now spent the past week or so sourcing components and i will be following Sky audio mod list with a few tweaks

this how its going so far

Hello,
I have recently develop this LM3886 PA100 power amplifier it does use DC servo and the amplifier boards can also be suited
with a cliping indicator vertical board, in this thread I show this combo of a stereo system which include everything displayed
all capacitors are from Nippon and the price for this set is 110€
If you are interested in just in one of the products you can check here the power amp boards or the supply:
https://www.ebay.de/usr/rocksandsound
Or just reach me through here.

Here is another prototype 2way project I work on.
W18NX003 is excellent unit and is basically perfect in all aspects of the performace. It is Purifi level of performance. Finally the Seas drivers with performance matching the price.
T25B in WG measures very linear on and off axis, and the distortion is great too.

The crossover is again quite simple, and both units are very easy to work with.

The cabinet volume is 19L, tuning ~38Hz.

First listening tests were very promising.

I have some matched 2SJ74V and 2SK170V.
Single, double or quad pair.

Price pr sheet: €100, + shipping.

If you have any particular needs, ask.

Regards
RM

These are from my vast collection. Never used. All from the same batch.
$12/each + shipping at cost

To quench all such questions, each means one piece. Price per pair would then be $24.

Regards
Roar Malmin

I somehow lost one of the blue jumpers for my ACA mini. Anyone have one they would be willing to part with?

* SA2022 - Modular High End Precision Preamplifier * See Project J below ***
* SA2021-NCH - New Class H * SA2021-NCH - New Class H * See Project I below *

Heavily inspired from books of Douglas Self, Bob Cordell and other great authors I decided to design a discrete power amplifier to learn how LTSpice can be used for my DIY projects.
Attached is the current simulation file and some information about the real world result: a very good working 2stageEF power amplifier with high performance.
The simulated THD performance is about 0.0004% at 20kHz@200W@8R.
Real life THD+N performance of working prototype amplifier is about 0.0015% at 20kHz@200W@8R (80kHz bandwidth).
Using the HP3585A spectrum analyser (100dB resolution) while running 20kHz@200W@8R test only H2 and H3 are visible above the noise floor.
To download the needed BJT/JFET/MOSFET/DIODE ltspice library file "Cordell-Models.txt" please visit CordellAudio.com - Home

During the years some smaller amplifiers based on the same topology have been developed. These projects have been discussed in detail and have been built successfully by different users. See the index below for more information.
In addition a high performance discrete opamp "MyDOA" and housekeeping circuits have been developed and built many times too.

More test results, THD plots and other information will be updated from time to time.

Have fun, Toni

-----------------------------------------

A) SA2014 (200W@8R, 400W@4R) Rev 3.4.2 amplifier (partially old name is SA2013) using 8 matched pairs TTC5200 and TTA1943:

• Latest valid PCB gerber files for input/VAS and output stage board can be found in post 979 and 980
• PCB gerber files for power supply (single diode bridge; v3.x; see F) and G) below for dual diode bridge) for one channel in post 1005
• Latest schematic and corrected BOM in post 1145 and 1146
• R28 (100R) needs to be reduced to 68R to get some extra PM stability.
• CCS mod for better thermal stability post 2028
• "asc" files can be found in post 1149
• pcb's are available via: sa2014 (at) aws-it.at

B) MyDOA v3.1 (my discrete operational amplifier) have a look at

• post #1255: MyDOA v3.1 final - schematic and gerber files
• MyDOA measurements
• pcb's are available via: mydoa (at) aws-it.at

C1) SA2015 V-MOSFET (70W@8R, 140W@4R) using 3 matched pairs IRFP240 and IRFP9240:

• post #1409: SA2015 final schematic, bom, gerber files - rev 1.3
• pcb's are available via: sa2015 (at) aws-it.at

C2) SA2015 V-MOSFET (100W@8R, 200W@4R) using 1 pair IXYS IXTH80N20L and IXTH48P20P:

• post #2185: SA2015 IXYS schematic ("product id": SA2017-VMOS-AB4-800)
• pcb's are available via: sa2015 (at) aws-it.at

D) housekeeping circuits 4.3:

• Schematic and BOM part 1 is here
• Schematic and BOM part 2 is here
• pcb's and PIC microcontroller firmware are available via: sa20xx-hk (at) aws-it.at

E1) SA2016 - L-MOSFET (70W@8R, 140W@4R) - 3 matched pairs Exicon ECX10N20 and ECX10P20:

• preliminary schematic for ECX10N20, ECX10P20 can be found in post 1761
• pcb's are available via: sa2016 (at) aws-it.at

E2) SA2016 - L-MOSFET (100W@8R, 200W@4R) - 3 matched pairs double die Exicon ECW20N20 and ECW20P20:

• preliminary schematic for double die ECW20N20 and ECW20P20 can be found in post 2105
• pcb's are available via: sa2016 (at) aws-it.at

F) SA2014 - power supply v4.0

• schematic for dual diode bridge ("big" sized: 150x150mm) can be found in post 2000 and 2001
• updated gerber files in post 2067, 2068
• pcb's are available via: sa2014 (at) aws-it.at

G) SA2014/SA2015/SA2016 - new resized universal power supply v4.0

• schematic for dual diode bridge (smaller size: 150x90mm) can be found in post 1987 and 1988
• updated gerber files in post 2067, 2068
• images of working test samples in post 2071
• pcb's are available via: sa2016 (at) aws-it.at

H) SA2012 - LME49830 (180W@8R) using 3 matched pairs IRFP240 and IRFP9240[/B]

• schematic can be found in this threads post 29
• gerber files in this threads post 31

I) SA2021-NCH - a 'New Class H' prototype using 3 matched pairs IXYS IXTH80N20L/IXTH48P20P and 4 matched pairs TTC5200/TTA1943

• single pair IXYS prototype schematic can be found here post 2902
• single pair IXYS working prototype can be found here post 2922
• 3 pair IXYS - v2.0 preliminary schematic - can be found here post 3117
• 3 pair IXYS powered amplifier testing can be found here and on the following posts: post 3094
• single slope current limiter can be found here: post 3177

J) SA2022 - Modular High End Precision Preamplifier

• SA20XX Amplifiers need a preamplifier - this project may fullfill your needs: post 1

INDEX / UPDATES

• 2013.05.10: Just4Fun: simulation of OPS using discrete darlingtons
• 2013.05.10: Just4Fun: simulation with MOSFET IRFP240/IRFP9240
• 2013.06.16: New schematics for revision 2.0RC1 available here
• 2013.06.21: THD performance of Rev2.0RC1: THD20k@200W@8R with distortion magnifier and VP-7723D 0.00152 % (bw. 80kHz) 0.00184 % (no bw. limit)
• 2013.06.29: Milestone SA2013-Rev2-RC1: All pcb's ready for mounting and cabling
• 2013.07.24: Prototype finished. Ready for extended hearing tests ...
• 2013.07.28: THD Performance of finished amplifier
• 2013.07.29: Updated schematics for revision 2.0 available here
• 2013.07.31: Updated PCB for input/vas and bias/output stage rev. 2.0
• 2013.10.13: Just4Fun - a symmetrical input/VAS variant
• 2013.10.14: The effect of too less gain margin
• 2013.10.17: Just4Fun: 2stageEF as current feedback amplifier variant
• 2013.10.20: Just4Fun: my discrete opamp V2 / my_doa_v2
• 2013.10.27: Just4Fun: my discrete opamp V3 / my_doa_v3
• 2013.12.29: Updated schematics/ltspice-file for revision 2.2 available here. Fix VAS current protection
• 2013.12.30: Milestone SA2013-Rev3-Alpha: new VAS topology improves THD
• 2013.12.31: New VAS topology real life measurements
• 2014.01.13: VAS current protection redesign: avoid overload / ringing
• 2014.01.13: VAS current protection redesign: better sticking behaviour
• 2014.02.16: The effect of current mirror degeneration on slew rate
• 2014.04.27: Distortion and overload tests - SA2013 v3.1
• 2014.05.03: IMD measurements - SA2013 v3.1
• 2014.05.03: Noise - SA2013 v3.1
• 2014.05.29: SA2013 v3.4 THD measurements
• 2014.05.30: SA2013 v3.4 IMD measurements
• 2014.05.30: SA2013 v3.4 Noise measurements
• 2014.05.31: Just4Fun: simulation with MOSFET VAS IRF9610
• 2014.06.09: Real life test results MOSFET VAS IRF9610
• 2014.06.22: Input/VAS/OPS schematics and pcb for revision 3.4.0 final
• 2014.06.26: Powersupply schematics and pcb revision 3.4.0 final
• 2014.06.28: Powersupply simulation for CRC snubber
• 2014.06.28: Powersupply schematics and pcb revision 3.4.1 (with added RC snubber)
• 2014.09.14: Revision 3.4.2: Final schematics and BOM
• 2014.11.29: Fighting the hum - encapsulating power supply using soft iron
• 2015.03.03: Playing with LTSpice - dual Tian probe and parameter stepping
• 2015.02.10: MyDOA v3.1 final - schematic and gerber files
• 2015.09.18: SA2015 with V-MOSFETs IRFP240/IRFP9240 - is born. A high performance 75W@8R, 150W@4R MOSFET amplifier
• 2015.09.19: SA2015 with V-MOSFETs IRFP240/IRFP9240 - measurements THD20k@50W@8R 0.0018%
• 2015.10.31: SA2015 with V-MOSFETs IRFP240/IRFP9240 - final schematic, bom, gerber files - rev 1.3
• 2016.03.16: SA2013, SA2014, SA2015 housekeeping circuits
• 2016.04.10: SA2015 with V-MOSFETs IRFP240/IRFP9240 - first powering procedure after assembling
• 2016.07.07: SA2015 with V-MOSFETs IRFP240/IRFP9240 - pictures of the finished 4 channel amplifier
• 2016.07.15: Housekeeping Circuits V4.3 - schematic and bom - part 1
• 2016.07.16: Housekeeping Circuits V4.3 - schematic and bom - part 2
• 2016.08.05: SA2016 with L-MOSFETs EXC10N20 EXC10P20 - measurements 1 - noise
• 2016.08.10: SA2016 with L-MOSFETs EXC10N20 EXC10P20 - measurements 2 - noise / THD table
• 2016.08.10: SA2016 with L-MOSFETs EXC10N20 EXC10P20 - using higher rail voltages to get 115W @ 8R
• 2017.01.31: pcb clearance, creepage discussions 1: EN 60950-1
• 2017.02.01: pcb clearance, creepage discussions 2: EN 62368
• 2017.02.05: SA2014 input stage reloaded: small mod of the CCSs for better thermal stability
• 2017.02.09: SA2014 heatsink thermal simulation with LTSpice
• 2017.02.20: New SA2014/SA2015/SA2016 power supply variants are working
• 2017.02.20: Off topic: Linkwitz-Riley 24dB subwoofer analog crossover - 2.1 system
• 2016.02.26: SA2016 with L-MOSFETs double die ECW20N20 ECW20P20 - singing - THD20k+N@200W@8R 0.0052%, THD20k+N@320W@4R 0.008%
• 2017.03.05: SA2015 with IXYS V-MOSFETs IXTH80N20L and IXTH48P20P - SOA simulation
• 2017.03.12: SA2015 with IXYS V-MOSFETs IXTH80N20L and IXTH48P20P - first powering
• 2017.03.13: SA2015 with IXYS V-MOSFETs IXTH80N20L and IXTH48P20P - measurements - THD20k+N@60W@8R 0.0018% (80k bw)
• 2017.03.16: SA2015 with IXYS V-MOSFETs IXTH80N20L and IXTH48P20P - schematic
• 2018.11.11: SA2015 with IXYS V-MOSFETs IXTH80N20L and IXTH48P20P - finished 4 channel amplifier ("product id": SA2017-VMOS-AB4-800)
• 2020.10.29: DaveZan presents a draft for a switch mode rail tracker class H design
• 2020.11.20: SA2021-NCH 'New Class H' by DaveZan and ASTX - prototype using IXYS V-MOSFETs and TTC5200/TTA1943 - lab test schematic
• 2021.01.05: SA2021-NCH 'New Class H' by DaveZan and ASTX - prototype working - excellent low distortions as expected
• 2021.01.05: SA2021-NCH 'New Class H' - prototypes first THD and noise measurements at 200WR
• 2023.07.22: SA2021-NCH 'New Class H' - assembling the 3 pair IXYS MOSFET powered amplifier
• 2023.07.25: SA2021-NCH 'New Class H' - assembling / preliminary schematic of 3 pair IXYS powerhorse
• 2023.07.31: SA2021-NCH 'New Class H' - first powering and measurements
  

USERS BUILD:

• 2016.04.11: Thimios build SA2015 - first power on, many tests on following posts
• 2016.04.12: Thimios build SA2015 - testing first sample
• 2016.04.15: Thimios build SA2015 - second channel
• 2016.05.19: Thimios build SA2015 - ready for hearing tests
• 2017.05.18: Thimios opened build thread: SA2015-V-MOSFET-Builders
• 2016.04.12: SGK build SA2014 - assembled!
• 2016.08.18: SGK build SA2014 - from build start to singing at post 1831
• 2017.01.05: SGK build SA2014 - internal view
• 2017.01.05: SGK build SA2014 - SMD variant of housekeeping pcb
• 2017.01.07: SGK build SA2014 - finished, front view
• 2017.02.19: SGK build SA2014 - panel switch pcb 1
• 2017.02.20: SGK build SA2014 - panel switch pcb 2
• 2017.03.12: SGK build SA2014 - Alternative auxiliary power supply
• 2017.03.13: SGK build SA2014 - Main power supply
• 2018.01.25: SGK build another SA2014 - now as monoblock
• 2016.11.22: AndrewT (R.I.P) build SA2016 - up and running using double die Exicons
• 2017.11.19: HYPERTUNE opened build thread: ASTX SA2014 Build Thread. 2 x 400WR with CNC machined case.
• 2023.11.02: HRDSTL starts building SA2014

NOTE: the pictures and schematics shown in this first post are from the initial beta project. Do NOT use them for production. Read above index carefully - there are links to the latest schematics, BOM and gerbers!

Pass' new HPA-1 is certainly getting good press.

Pass Labs HPA-1 headphone amplifier | Stereophile.com

Do we know anything about the design? Push-Pull or single-ended? Based on any currently known topology (Aleph, etc.)?

Just trying to figure out what Pass considers the best approach for headphone amplification.

I have a 2x25 Watt class D amp with CS8673 chip.

It can take maximum voltage of 24 Volts.

I have a 60 watt solar panel with maximum open circuit voltage of 22 Volts.

Is it possible to power such an amplifier directly with a solar panel with maybe some filtering capacitor of several thousand uF? Or should filtering be omitted ?

I live in egypt here you have always sun and it never rains.

Anyone tried running a class D amp like this?

A friend of me want to buy one of both, but he is unsure, which of both should he prefer.
Maybe anybody have heard both at the same time on a listening test.
I can imagine that both devices have excellent sonic character. But maybe the Ultra Analog D20400a sounds more musical.
Thank you for advices.

Here some links:
https://www.passlabs.com/sites/default/files/d1_om.pdf
pass labs dac - d1 0 pass labs - Hifishock
PASS Labs - D1 - Familie Witt
Ultra Analog 20400A – Threshold-Lovers

I have in my system one DOZ preamp revison A
though form this i drive 3 amps
one is for may main speakers
second is my secondary more effective speakers
and third is my headphone amplifier

so depending on demands i power up the correct amp

Still that means that the impedance of my 3 amps is always present at the preamp
so that means impedance is 47+27+27

Anyone thinks that this effects my quality of sound ????

All transistors are 300V devices.
The example shows 1.44Vp input and gain x101 gives output 291Vpp.
Distortion is THD 0.001%
Do not build this ...! 😀

I love the Morel MDT 33, can somebody tell me whether the ET 338 is any significant upgrade? I mean, sonically

Sell individually or all together the following used inductors
- Jantzen wax copper coil 14awg 0.47mH, 0.17 ohm, price new 84eur,my price 38 eur plus shipping

-Jantzen wax copper coil 16awg 0.6mH, new 65eur,my price 30 Eur plus shipping.

-Mundorf VLCU 15 0.39mH 0.18ohm, new price 50, my price 25 Eur plus shipping.
See pictures

Used twice. Works fine just not getting any use over here.

$55 - Including shipping within the CONUS and transfer fees.

Hi, everyone !

Throughout my youth I researched and designed class AB high-power audio amplifiers. I don't know why I did this... 😆 because I don't need hundreds of Watts of power to listen to music. And it doesn't make sense to power up a monster amplifier just to listen at a few Watts, which is more than enough for me. It also takes a lot of space. I don't like class A either because of it's high consumption, and neither chip amps. So I thought, what if I convert one of my power amplifier schematics into a small, miniaturized amplifier with SMDs ? I want to make it as small as possible, and as good as it gets.

And I came up with this schematics. 🙂
It is based on my high power amplifiere of 200W, which I already buid it, and it still works perfectly after 15 years of stressfull conditions in a comercial business of a friend of mine.
You can see it on my website: https://marus-gradinaru.42web.io/Audio/ZAL200V3/main.html



So, this new schematic it is powered at +/-16V must deliver 7W into 8R and 15W into 4R with 1Vrms imput signal. You can see the simulated parameters in the top-left of the image. Because the years have passed and I've forgotten a lot of what I studied about audio amplifiers, I want to talk to you before building it to make sure I didn't do anything wrong. First of all, I would like to discuss about the transistors used... Remember, they all must be SMD components (except for the power ones, obviously) !

The input stage.
In the input stage the most important is the noise factor of the transistors. And a bonus will be if they are a matched pair (NPN+NPN and PNP+PNP). As strange as it may seem, I haven't been able to find any decent low-noise transistors pairs in SMD package. The closest to what I want are the BCM847DS and BCM857DS. They say that the noise figure is 3dB typical. Will this be audible without music ? It is said that only the 10K volume potentiometer generate about 12.9 nV/√Hz, so it will ruin any low-noise transistor anyway... I don't know what to say... If you know a smd package with two NPN and two PNP matched transistors with lower noise than 3dB, that will not cost a fortune and they can be found easely, please let me know. But I think the chances are small, because I've already read here and haven't found anything suitable.

VAS stage.
In the VAS stage, as I remember, the most important is the Cob of the transistors. The Cob of the first transistor is more important than the second one, but they all needs to be low.
The BC847-857 has 1.5pF and 4.5pF. They are low enough, but I don't know how bad is if they are not the same.
The BCX56-53 has 4.5pF and 7pF. Still a little different...
In the simulation, the slew rate seems symmetrical, around 8-9V/us...

Output Stage.
Here, I selected the BCP56-56 as drivers.
In simulation, at maximum power, there are some 40mA current peaks and the average dissipated power is 120mW. The transistors are rated for 1A and 1.5W, so I gues they will do, right?
For the power output I thought about using MJE15030-31, which I used in my high-power amplifiers as drivers. I know they are not made for this, but do you think it will work for this little amp ? The transistors are rated for 8A and 50W. The peak output current in 4 ohms is 3A per transistor, and the average dissipated power per transistor si 6W max. Do you think they will hold ?
Another disadvantage would be that the gain is a bit nonlinear:
NPN hFE: 150 @0.7A / 100 @2A / 75 @3A
PNP hFE: 150 @0.7A / 120 @2A / 83 @3A
Will this matter much ?
I would be interested if you know of other more suitable output transistors, but only in the TO-220 package.

From a Hammond organ. Part# AO-20936-2. Approx. 10K:8ohm. $20 including shipping with CONUS


From a Magnavox 169AA amp. Approx. 6.6K:4ohm. $20 shipped within the CONUS


From Sony TC200 RtR. Approx. 2.5K:8ohm. SALE RESCINDED



Edit: If you have a match for one of these output transformers, I would be interested in purchasing.

Hi All,

I recently took the plunge on a pair of TAD 1601a woofers and the TH-4001 horn that popped up for a good price. So now I find myself committed to a build..
It's always been a dream to replicate the exclusive 2402, but purchasing the TD-4001 drivers is out of reach right now. I was considering a pair of JBL 2450H's, as I've seen them recommended here as a good match for the TH-4001?

I plan to go active, with a digital crossover via minidsp flex. I have an Elekit tu-8900 for the horn. And an Amp Camp amp for the woofers at the moment- I realise this is probably a bit underpowered, but have to work with what I've got until I can buy or build something with a bit more grunt. To compensate for this, I planned to cross the woofers at 80hz or so to a ported Rythmik 12" sub I have.

I was thinking of crossing horns at about 600hz. Tips on crossover for this combo also appreciated.
Frying the compression drivers is probably my biggest fear with the digital crossover, so was thinking 33 or 47µF film capacitor in series - need some advice on this especially.

Eventually I'd like to build full size cabinets in the style of the originals, but for the time being (due to space constraints and the amp/sub situation above) I was thinking of building a temporary 120 litre sealed cabs for testing, since I'll not be asking too much in the bass department of 1601a's.

Anyway just thought I'd put this out to the brains trust for some opinions on the approach and any considerations I may have missed. Realise there is a lot to learn/consider so not in any rush, and flexible with the plan, these are moreso just initial thoughts. Thanks in advance!

I purchased this from an estate sale a few years back. I have no use for it, so time to clear the closet. Untested but could make a killer guitar amp for the right builder.

$50

Pair of DT880's in very good condition. Earpads are like new. Includes original box and leather carrying case.

$100 - Including shipping within the CONUS and transfer fees

Amp works perfectly, I've just switched back to using my Mofo monoblocks, so putting this up for sale. All components were sourced from Mouser/Newark. I've installed two AmyAlice filter, one per channel. Includes a 36V 5A generic power supply. Note: There is a switch and XLR jack installed, but they are not connected.

$450 - Including shipping in the CONUS and transfer fees.

This is the new discussion thread for the Sapphire amplifier.

Previous threads,

183588-headphone-amplifier-drop-replacement-phonoclone-3-vsps300

160460-rjm-audio-gainbloc-preamplifier-mk-i

are redirected here.

Information about the kit group buy is at this thread.

I have a few standalone DACs that I'm no longer using. To simplify things, all prices listed include shipping within the CONUS and transfer fees.

Musical Fidelity V-DAC(the first version). Includes power supply. $60


Fiio K11 R2R. Includes power supply. $110


SMSL M100. No power supply included. $30


Angstrom Model 200. This is an older high end surround sound processor but can be used as a 2 channel DAC. I believe it is based on Multibit converters but not entirely sure. Beware: This unit does not have a fixed output. Volume is adjusted from the front panel using up/down buttons and there are only indicators for minimum and maximum output. There is no display indicating actual volume level. $100

Hi guys. I'm selling off a lot of valves. Let me know if interested

• loads of type 26 test good, ST and globe, £18 and £20 each
• A few 10Y test strong £90
• Loads of other valves as listed on ebay, 20% off ebay prices at least

Check my ebay listings. Here's one and you can click "sellers other items"

https://www.ebay.co.uk/itm/146422562280?

Best, Andy

Clearing out my closet of drivers that I will probably never end up using. I can accept PayPal or Zelle for payment.

1. Altec 412C 12" Biflex Woofers pair. The last time I had these hooked up, 1 worked fine but the other one only produced sound from the inner cone......SOLD




2. B&C 12CXT 12" Coaxial pair. These are used pulls from EAW speakers and have EAW part numbers. But I am 99% sure these are B&C drivers. The dust caps were removed due to damage. I just never got around to replacing them. Drivers are 16ohm impedance and will include the custom EAW crossovers.......SOLD



3. Maxo NE1230-8 12" woofer pair. Open box but never used.......SOLD



4. Eminence Beta-8a 8" woofer pair. One BNIB, one open box but never used........$40



5. Eminence Delta 12LFA 12" woofer pair. Lightly used. Foam gaskets have some deformation from a mesh grill that was attached in front of them.......$100




6. Eminence ASD1001 1" compression driver pair. Lightly used.......$40




7. Eminence PXB2:3k5 crossover pair. Lightly used........$20

I bought the drivers for the 10F+RS225 FAST speaker build, but I am no longer able to continue with it. A shame, since it's a great project, and has been very popular and well received. One of the bass units is new in box, the others I bought used. These would be around £350 new, so hoping for £240 but can be discussed.

All details here:

Reluctant sale of my SET amp with 6SN7 into 6L6WXT+ in triode. 2 chassis, signal+PSU with 5V4 and 2x chokes. It sounds very nice and I like listening to it. I'm very pleased with the 6L6WXT+ outputs, much better than EL34s and quite a surprise.

Premium parts, Sony OPTs, Russian teflon caps, Nichicon Gold Tune and AN Kaisei bypass caps. NOS 6SN7.

Each chassis is 260 x 300mm.

Pickup from London Kensington. £260. A bit bulky to post but not impossible.

Attached are photos of my DM-22's bought on "Parts Only" basis\. The crossover was apparently going to be upgraded and parts are loosely soldered but looks very tacky soldering..... So I need assistance to assemble please. As well as components pictured, the Tweeters each have another Mundorf 4.7uf cap in the Positive lead just near the Tweeter. I could maybe patch something together if I have a schematic of the circuit. any advice will be hugely appreciated.

I have a rather large quantity of these extremely versatile MOSFETs. They are of -85 vintage.

Can be sold in pairs or as sealed bags of 50.

Rated at 160V they can in many instances be used instead of 2SJ79/2SK216.

Perfect as drivers in power amps.

$20/pair. Shipping at cost.

Regards
RM

My stock of these extremely hard to find 200V MOSFETs are dwindling at an alarming rate so I have to raise the price a bit.

New price will be $13/pcs.

Please also note that in many situations you can use the lower voltage ones, the 2SJ77 / 2SK214, which I still sell at $10/pcs.

Regards
R

I am looking to make my horn-loaded D54 2" Midrange Domes a non horn-loaded flat D54-AF midrange to widen the bandwidth at the expense of 2dB sensitivity.

It looks like the older Dayton DC50 which has a 3 screw hole connection for the flat faceplate to the magnet / voicecoil assembly will WORK as well.

Let me know if you have a pair of dead midrange domes (D54 AF/ D52AF / DC50F) or these associated Flat faceplates to sell.

I have a US mailing address and I can pay via PayPal.

Regards,

Dan

Built this Ampeg B15N clone over 10 years ago. Based off the details / info from https://www.thallenbeck.com/blog/posts/d-i-y-ampeg-b15n-fliptop-clone/

Amp has Fender 6L6 tubes, RCA 6SN7 (original used a 6SL7 in driver seat and 6SN7 as PI, but I had two 6SN7), and an RCA 5R4 Rectifier.

Unit originally was a 6L6 / 6SN7 / 5R4 based Carillon amp powering a Church Bell. The power supply reused the original power transformer and tubes, while the output tranny was replaced with a Fender Hot Rod Deluxe Transformer. There were 5 more octal tubes in the original amp (two of which were more 6L6 output tubes) that were not needed for the B15N, so power transformer has lots of spare power.

There were a few minor changes, but most of the circuit is the B15N circuit on the website and attached schematic. Volume, Bass and Treble pots, as well as another pot on front corner for setting feedback, and the one on top to add additional resistance to Cathode resistor. Single input only, Cathode Bias (common 300 ohm) instead of Fixed Bias were biggest changes. Don't remember as this was over 10 years ago. Amp is bolted to a Bamboo cutting board.

This is a working amp and sounds great with my guitars.

Looking for $250 + ship. This unit is heavy.

Looking for one pair of Scanspeak Revelator 7" 18W/4531G 4 ohm drivers.

I have both a Canadian and US address in Port Huron Mich 48060.

I will pay via Paypal as well...

Let me know what you have.....

For Sale: NuTube B1 Based Preamp . Two inputs, one output

Unit functions perfectly and chassis is a bit dirty. There is no noise, and only have the two inputs, but switch has ability to add two more inputs. I never needed more than two so it has only two.

$275 + ship or pickup in West Sub of Chicago.

I bought pcm58 boards and I am changing the opamps in one of them for opa1611 output.

I planned to use a trimpot of 100k to attenuate the signal. So far so good...

I traced the path of pin6 of output opamp (which is in buffer mode /filter).

The signal goes to the ground,

Then the + of the RCA has a 100R to ground.

Maybe it is late, I cannot figure it out. It must be simple.

It has a relay switches, I tried on and off, no difference.

On the schematic it says 100R in series from Pin6 to + of rca with 10K to ground.

There are the two resistors which both measure 100R, one of them could be the 10K and they are reading in // no clue

now have NEW
SJEP120R125 30pcs
SJEP120R063 34PCS
SEJP120R063C2 5PCS
SJDP120R085 15pcs

Hi all, Josh from Australia been into hifi for the better part of 15+ years. I’m here for some expertise if possible. I had never thought of getting into DIY audio until I came across the value for money that could be had with going that route. With that I decided to purchase an Ian Canada streamer kit and am needing some help with getting it up and running.

Would appreciate it a lot if someone could point me in the direction of the right section to post my query. I believe it’s most likely a software issue and not hardware but could be wrong.

Thanks

Two drivers, used in living room speaker for about 10 years. Signs of use, diaphragm of one has superficial scratches. Kids have been pushing the central dome in. Working, nice way to try out Troels projects on the cheap🙂

Pick up in Olari, Espoo, Finland. 100€ or name your price!

Hi, does anybody know the max. rated V for this step-up/down 4:1 transformer? I'd like to try it in my proto of a tube preamp, to decrease the gain and in place of a coupling capacitor, before I order something fancy like Lundahl. The voltage at the ouput is about 180-185V, current probably not more than a few mA (last stage is the White cathode follower).

As some of you out there might already know that I built Discrete R2R DAC ver. V1.3 since 2020, and keep building / selling it till now.
This new version of V2.50 has more precise, lower noise reference voltage, and also a total re-write the code for FPGA.
the DAC is hand made, and hand matched resistors just like older V1.3. It supports 16~24 bit , 384K , distortion around 0.003%~0.004%. in Raspberry Pi setting, it uses Generic I2S DAC as driver, and turn off the software volume control for best result . It is powered directly from Raspberry Pi GPIO . It supports Raspberry Pi 2,3,4 and 5.
Price is USD206, and as for shipping cost, I ship via FedEx Priority International , USA = USD33.90, and Europe country = USD36.90.
For those who are interested, please PM me , thank you.

Moving to a new house is a great opportunity to clear the shelves of stuff that’s not needed any more.

I thought I had sold all I had, but apparently I hadn’t.

So I still have several hundred pairs of the highly sought after Toshiba 2SA970BL - 2SC2240BL. They are bandoliered and will be sold in pairs of minimum 50 pairs at $5/pair. Shipping at cost.

Thanks for looking.

R

Dear reader,
I think it's time for you to put your own OREAD-EQ into practice.

Perhaps the original discussion and finding thread has become a bit too long and confusing, so I'm starting a brand new container for all our own builds of this interesting and certainly much underrated MM phono equalizer.

To get you in the mood, here is a PDF document containing all the image files backwards, i.e. up to just before the beginning.

I wish all DIY enthusiasts a lot of fun with OREAD, a daring concept. You will find all the necessary information in the thread itself, the components used are available worldwide and with @catd's circuit boards you can easily and absolutely safely rebuild OREAD.

Other board versions are also very welcome.

All the best to you,
hbt.audio

Dear all,

Recently acquired a Sansui Sr525. It was spinning very fast and with high wow and flutter as measured by an Android app.

Did these and managed to bring the speed down to 43rpm on the 33rpm setting:
1. Replaced the fine pitch controls and VR1 and VR2 on the motor board.
2. Opened the microswitch and cleaned it as much as possible.
3. Replaced all electrolytics caps on the power and motor control boards.

It is the slowest speed I could get by putting the fine pitch control and the trim pots to the slowest setting.

I have since replaced the zener 5.1v and 2 ceramic caps near the dual transistor at the motor circuit, to no avail as well.

Any suggestions? Thank you very much!

Dears,
This is second (and last) blast from the past project that I will publish. Its from early 2000's when I was very much into doing different audio things.
Other of my old projects have no much difference from usually seen executions, so I will skip those.

As elementary school kid (in 1977), my older sister left me her BSR turntable system (in Yugoslavia than called Tosca) and some 50LP's, good stuff of the time, Leonard Cohen, Dylan, Cat Stevens, Janis Joplin, Roberta Flack, Jimmy Smith, some classic and so on... Anyway, I felt in love with LP's and HIFI forever, this still goes on.
Anyway, few friends (actually their parents) had Thorenses, Sondeks and Duals, , I always wanted proper turntable. By the time I made my own money, CD came into play and I bought one of the first Philips CD player.
Few years after I still wanted TT, bought one crappy example, throw it away and decided to make my own. Intention was not to make hi end piece, but to make vintage looking TT similar to those that I was wishing for:
This is the result:

I offer here for sale the F5 V3 amplifier boards, completed with good quality parts and orig. Toshiba jfets. I would like 120€, plus shiping, payment by paypall.

Has anyone ever build a PLLXO with LR instead of RC Filters?

Is the any calculator to desgin it?
Many thanks

Hi All,

Ok so this is my first post here so Hi. Picked up an Audioromy m828a FU29 tube amp from ebay - came quick, seems pretty well made.

I wanted to get the Bias and Balance right before I started using it extensively, so went about looking at it's guts. It seems the one I have differs from the schematics I have seen and the photos of the PCB apart from one person on this forum about a year ago who had gone about a similar question.

It does seem that the information been put out by some of the sellers of this amp is not compatible with what is actually in the unit. I wasted a lot of time stupidly trying to bias via the cathode, as there seemed to be a 0.4ohm resistor there (evidently not really). I could not get a real mv reading across to determine adjustment to get to 50ma total on the combined cathode.

So the 829b tube has a single common cathode and two anodes, essentially two tubes in one. It looks like the more recent versions of this Audioromy amp have no resistors for the cathode to determine the current here, but instead uses 1ohm resistors on the anodes for each half of the tube?

The attached image of the PCB area for one tube (from the other thread but is same as mine) shows the anode resistors and the white wires heading off to the top of the tubes.

The other attachment shows the instructions that have been sent around from the various sellers about how to bias the unit.

I suppose my post is here to highlight this disparity to anyone else who may have been confused about this and also to ask, can I adjust the bias and balance correctly via the supposed 1ohm anode resistors???

If it were a case of a simple in at cathode, out at anode analogy, I see how it wouldn't make any difference where the mv reading is taken? However what with the screen, grid in between the two, absorbing some of the juice, this reading might not be correct?

When talking about tube ratings, is the 50ma applicable to this tube in terms of cathode current or is it a more general cathode / anode current, making the location where this reading is taken irrelevant?

I am new to tubes since about a few weeks ago, so have a hell of a lot to learn and will refresh my basic electronics knowledge in the process.

Appreciate any help on this as I am going to attempt to bias / balance these tubes tonight and do it properly (ideally a self balancing circuit would be my solution?)

Cheers,
Rich.

The 2N3055 power transistor was introduced by the Radio Corporation of America (RCA) in the early 1960s. It was one of the first silicon power transistors, offered unrivalled second breakdown immunity and found many applications particularly in audio power amplifiers.

Under
http://www.diyaudio.com/forums/solid-state/10337-amplifier-based-2n3055.html
there is a circuit collection
check out also this thread:
https://www.diyaudio.com/community/threads/2n3055-the-early-years.382690/
early advertisement is on page 67 under
https://worldradiohistory.com/UK/Industrial-Electronics/60s/Industrial-Electronics-1965-01.pdf
(this page I have upload here on page 26 in post #505).
and last page (page 64, feb. 1964) under
https://worldradiohistory.com/Archive-Electronics/60s/64/Electronics-1964-02-28.pdf
(this page I have upload in post #518)

I want to have a bunch of such commercial famous power amplifier models and UK/US brand names made in the 1960s (only with quasi complementary output stages).

Thank you very much for your hints.

Hi,
I am whitepawn and i just signed up for forum. I love TO-3 package transistors and MOSFETS. I also like vintage electronics components. Regards to all.

In three-way crossover design, besides meeting points between tweeter/midrange and midrange/woofer, there’s a minor point where tweeter and woofer met each other.

For instance, the red arrow is the stated point. And it locates approximately 14dB below reference line (0dB).



Is there a rule (or a rule of thumb) suggesting how much dB below reference level should the tweeter and the woofer meet each other?

Cr. for picture: PassDIY