Hey Guys, I have found this forum invaluable in helping me evaluate which sub I want to build to start my mini rig. In particular the Xoc1 TH18 thread has me sold thats the way i want to go. Thanks for having me!

Hi guys, new to the "business" and trying to build a wifi speaker 😀 will be fun

I heard these speakers by someone who tried to build Dunlavy SC V1 clone type speakers. They used two Focal Audiom 15 inch woofers. The model number for the woofers were 15VX. These were top of the line Focal Audio 15 inch woofers, 2 Focal Polyglass midbases. The model number for the midbase was 7K6411 and a Raven R2 ribbon tweeter.
The speakers were about 6 feet tall and weighed 335 pounds.

They speakers had a nice soundstage and the bass was tight with good extension. These woofers were very impressive.
Now, he couldn't do a crossover like Dunlavy. Dunlavy could make speakers that used ok drivers, but make the speakers sound great.

I remember i heard the Dunlavy SC-IV speakers that used all Vifa drivers. These speakers had an amazing soundstage and sounded very layered and the bass was fast and tight. I always though what could Dunlavy have designed using top of the line drivers like Focal at the time or Scanspeak.

Here's a pic of the speakers he designed.

I've been trying to find a reliable formula to calculate the total group sensitivity of a relatively odd configuration and number of LF drivers. They would be arranged as close as possible to each other.

In my own personal scenario ->

- 3 identical 12" LF drivers, wired in parallel, individual base sensitivity of 87 dB/2.8V/1M per driver, arranged in a triangle.

- what would the total sensitivity be of all 3 drivers playing together at frequencies lower than the equivalent of 1/2 WL?

With an even number of 4 drivers connected 2 in series, then the 2 groups paralleled, we'd theoretically observe a 3dB gain from doubling the driver count and another 3dB from doubling the cone area, but lose 3dB from cutting the drive voltage to each woofer of the series connections. That leaves us with a total net gain of only 3 dB if we only count the frequency range that falls in the 1/2 WL CTC driver spacing.

With an abnormal quantity of drivers, CTC spacing and adding in series.resistance from a thinner awg, it becomes a bit more complicated to figure all this out. Short of putting it in a software sim, which isn't always accurate, there has to be a better way to get a closer answer.

V-FET lottery amp #038 P-channel from first lottery
Original, unmodified, perfect condition
In addition: 2 Bulwark FE and 1 Tuba filter
Asking price: 700CHF + Paypal Fees and Shipping

Do i need to worry about baffel step correction if i measure all my drivers in the finished speaker cabinet or will that measurement already account for it? Thanks! Travis

US patent 5,612,646 (PDF version) discusses Berning's ZOTL circuitry (there are actually commercial amplifiers), where instead of using a regular output transformer, the output tube is fed through a high frequency ferrite transformer by the load and MOSFET bridge. Begning claims significant improvements in performance as the high frequency transformer supposedly has little impact on audio frequencies (the switching frequency is suggested around 250 kHz).

A diyaudio member, hifizen, suggested to me that a better design would, instead of having a switching bridge in the signal path, use AM modulation, thus still allowing the use of a high frequency transformer instead of a regular OTL.

I'd like to get some opinions and discussion on the pros and cons of these two suggestions, as well as implementation caveats to watch out for (I actually intend to build one or the other, and have procured appropriate ferrite cores).

Hello everyone,
I have for sale pair of DIY finished boards of B&K st 140 amplifier built on the original exactly schematics.
Construction with components of absolute audio quality and definitely superior to the original:

• Nichicon Fine Gold audio capacitors
• Nichicon MUSE audio on the signal path (green)
• MKP bypass capacitors (Polypropylene)
• Cornell Dubilier silver mica capacitors
• ORIGINAL HITACHI K135 and J50 final MOSFETS
• Construction with Cardas tin.

Calibration as service manual 200ma @ 20kHz and zero DC offset (see photo) and absolutely perfect measurements in terms of bias, DC offset and THD (see measurements).
Power supply required dual 60V DC to have the nominal power of 105Watt/channel on 8 ohms.
Sound very well and powerful with NO hum and perfectly stable in temperature and elecrtical parameters.
Big heat sinks is not included.
Price request 80 Euro plus shipping (From ITALY).
Consider that the Hitachi mosfets alone are worth the asking price.
Some pics:

The TDA7293 series are underrated gems in the DIY world. This chipamp, with its modular structure, clip detector, mute-stby functions, low noise and low distortion, produced with DMOS technology, actually has the potential to compete perfectly with National/TI's LM3886. On the other hand, it is common practice to use chipamps with a buffer due to low source impedance demands and relatively high input bias currents. Likewise, with composite feedback applications, both the noise and distortion efficiency of chipamps can increase significantly. In our implementation, two matched N-channel JFETs, together with the PNP transistor, operate as a complementary feedback pair as a high-impedance, high-CMRR differential input buffer for the TDA7293. The JFE2140 / LSK389 LSK489 dual JFET combination used provides significant improvement in THD and noise compared to the use of the chipamp alone, thanks to its extremely low noise. The composite feedback rate is 26dB (20x). In this way, ~1.25v RMS input signal is sufficient for full power. On the other hand, thanks to the DC servo circuit established with TI's low-noise, low-offset opamp OPA277, the DC offset remains below 1mv.

Our inspiration for our design was Bob Cordell's LSK489 application notes and JFE2145 datasheet.
https://www.cordellaudio.com/JFETs/LSK489appnote.pdf
https://www.ti.com/lit/ds/symlink/jfe2140.pdf?ts=1717672324923&ref_url=https%3A%2F%2Fwww.ti.com%2Fproduct%2FJFE2140
https://www.st.com/resource/en/datasheet/tda7293.pdf
https://www.ti.com/lit/ds/symlink/tps7a49.pdf?ts=1717660447218&ref_url=https%3A%2F%2Fwww.google.com%2F
https://www.ti.com/lit/ds/symlink/tps7a3001-ep.pdf?ts=1717738722969&ref_url=https%3A%2F%2Fwww.google.com%2F


The ancient 78xx 79xx series regulators, which are well known in the electronics community, have been used in audio circuits for years thanks to their stable structure, high PSRR rates and relatively low noise(?).
Measurements of 78xx-79xx ICs (even though noise values such as "0.003% Vo" are given in their datasheets) have been found to reach noise values of 500uV - 1mV in the audio band, which may disturb sensitive ears, regardless of the input noise. Of course, such a supply noise is meaningless for modern audio opamps whose PSRR is around 120dB.
However, especially in discrete applications (since PSRR efficiencies are quite low), this level of noise will be disturbing.
Although complex, discrete, parallel-hybrid low-noise solutions have been produced to solve this problem, these applications remain a troublesome alternative due to application difficulties, additional noise due to the area covered by the regulator, and the necessity of matching components in some applications.
Our application provides a good and affordable alternative to all these difficulties. TI's low-noise regulators TPS7A4901 for + rail and TPS7A3001 for – rail form the heart of our application. The effective noise amounts of these regulators in the audio band are below 15uV (RMS) level. In addition, while PSRR rates are 60dB in the 78/79 series for 100-120Hz, they are around 70dB in the TPS7As. On the other hand, load and line regulation rates and transition responses are significantly higher than the 78/79 series.
Although the input voltage of these regulators is limited to a maximum of +/-36v, input up to +/-60v can be applied thanks to the input voltage limiter used in our application.
Since the pinout of the 78/79 series is used directly, they can be used as a one-to-one replacement in applications where these regulators are used.

EPIC S

EPIC S


Positive Regulator Schematic


Negative Regulator Schematic


Final prototype measurement of EPIC S.
1K-1NF input filter
47K-4.7K NFB Resistors
4.7mA Input bias
Power: 78W 8ohm (2x42V)
Input sensivity: 1.25V
Slew Rate: 8V/uS 8ohm/1nf (JFE2140)
Slew Rate: 9V/uS 8ohm/1nf (LSK489)
Bandwidth: 5-75khz -3db
DC Offset: <500uV



EPIC S Output Noise

Hello,
I'm building a P3A amp that will be paired with the ESP tone control preamp. The pre already has an output cap so I'm wondering if there is any reason to keep the input cap on the P3A, and if not, could I also eliminate R1, R2, & C2?

This Error-Correction/Composite Combo amp is based on Mr Evil "Unnamed feedback method explored" and Nickolay Shvydky "My ZD-50 ultralow distortion chipamp"

Output power at +/-29.5V: 8 ohms clip at 42W, 4 ohm clip at 65W. It is very stable in both EC and Comp mode. Ans it behaves very well after clipping.

I could only measure its THD+N very roughly using Focusrite Solo 3rd, which has a minimal line-out and line-in THD+N of 0.002%.

U1 is OPA1655 and U2 is OPA828. For error-correction(EC) mode, RV1 was set at 330ohm. For composite (Comp) mode, RV1 was set at 680 ohms.

Only looking for the SuperCables Cookbook now. The Vacuum State site is no longer available, so hoping to find someone who wants to part with their book.

Well, origin thread is here : Iron Pumpkin(s) and other smaller vegetable animals

If nothing else, read at least first several posts on linked page , to grasp enough info about concept itself.

This one having two purposes :

-placing all necessary info about final iteration,

-trying to layout clearer picture of what's fuss about,

-with edits of this first post - making comprehensive list of tips and tricks and funny fine details , and answering on any clever or dumb question you'll possibly have ......either here or further in thread

(3 purposes then , not two )

edit at 22.05.2020. short how-to-do for Iron Pumpkin SE, referencing to post #2:

do not connect buffer output to Turtle

maximize trimpot R36 (measure across R39 to confirm max value)

R37 position is irrelevant for now

if you're sure that you connected everything properly, just power it on

set positive and negative rails to +/-12Vdc , with trimpots R9 and R10

power off, place DVMdc crocs across R34, power On then fiddle with R36 to set 20mV across R34, then fiddle with R37 to set 0mV DC offset at output


do everything the same with other channel, connect outputs of buffers to Turtle, enjoy

Earlier in the Le Monstre Preamp thread, we posted schematics and spice files for 3 different line level buffers.
www.diyaudio.com/community/threads/preamp-for-hiraga-le-monstr-2024.421562/

They all have JFET inputs and use 4 complementary transistors in total.
We have now built and measured them all, as shown in the pdf attached.


Patrick

.

Hi

The big thread of "100W Ultimate Fidelity Amplifier" is a chaos.
i need time to search through all the page and mark all i can find.
pcb is done in yellow by jlcpcb.

Gerber and all other documents are in post 13908: here
input BJT i use the recommended KSC1845, driver are 1381 and 3503, power mosfets are the renesas 1058/J162
as C4 it is written 220µF, and XRK use a polymer elco with 330µF. I use a orange 1000/16VµF by epcos
for C9,C16, C12, C15 i use Panasonic 680µF/50V
input cap is a red polymer panasonic 2,2µF/400V instead of 10µF
i use the lower gain setting R11, R12--> 550R and 20k
i did my first output coil...its not nice done but it has about 0,9µH the resistor is under the pcb

bias setting:
post 6686 bias at 100ma-170mA, wrote about goldmund amps--> bias 200-300mA
my bias is set according to the hint of post 7753 by bimo to 400mA. the amp is working fine.
post 6971 test by XRK as an Class A amp with 1,3A works fine...big heat sink is needed!

i used for the first test a 0,65K heat sink.
i plan to use a 4U/300 case by modushop with a 300VA 2x24V sec. transformer

i will just check the other channel.
psu voltage is 31 per rail and bias is after 2 hours 420mA stable. no heat problems, no smoke..

Gain is about 31dB, at 8ohm load about 29WATT.

if you have any hints , let me know.

edit:
Apex directory - done by XRK ..thx:
here:

edit: 26.8.2024: set bias current back to 400mA #post 104
edit: 25.03.2025: post 123 latest PCB Gerber by Peter(Kleinhorn) - thank you!
post 123

kr
chris

I have a distortion in one of my tweeters on my 3-way. The distortion occurs only at certain frequencies and above a certain volume. The distortion is pretty deterministic, I can reproduce it. They are old 3 ways energy speakers from the 2000. I managed to isolate the distortion problem : it is only one side, and because I can bi-wire it, I can confirm that the distortion is coming from the tweeter and not from the mid or bass (because mid and bass share the connector).

I also swapped sides of the amplifier, so I know it is the tweeter on the speaker and not the amplifier that is problematic.

The screw to remove the drivers are not accessible (see: https://rvb-img.reverb.com/image/up...,t_large/v1639605839/olidljagmyhg8zmbkcx4.jpg), so I would like do the debugging and part sourcing before taking them apart.

Is there something I can do to pinpoint where the problems, i.e. crossover, dome, magnet, voice coil? And the potential solution?

Thanks

I don't really post up here as often as I should, but I have been posting as tarior on AudioKarma for over 20 years now.
At any rate I have a ton of obsolete chip amplifiers and some excess small signal transistors. I would like to trade them for parts I can use, or, I can sell them outright.
All of the transistors were sourced from Digi-Key, Arrow, or Mouser. I'll start with parts I don't have enough of:
KSA1381, 2SC2240/A970, 2SA1370/C3467, KSC1845/A992 with a gain range higher than F, KSA1220A, through hole versions of 2SC4207/A1552, 2SC1904/A899, 2SC1885/A912, 2SB568, 2SB718, and TDA7109P. If you have interest in any of the parts, and have some of the ones listed, I'll let you determine the trade ratio, within reason. If you would like to buy any outright, we can also talk about that.
First up, we have a few transistor part numbers.

KSC3503D 200-300 available.
KSC1815GR 2000 available
KSA1015GR 500 available, maybe more in the future.
KSD1616A(L) 2000 available
KSB1116A(L) 2000 available.
MJ2901 NOS 9 available.
SGSD00034 6 pieces
SGSD00032 2 pieces
SK3009 3 new, one used. I'll throw in any used ones for free.
SK3014 1 new, two used. ""
Tektronix 151-0337 One piece
SK3113 Germanium damper diode One
2SC3976 3
2SC3982 2
2SD1441 1
2SD1453 1
SGSD00042 3
SGSP321 2
SGSP579 2

Next is the long list of obsolete chip amps.

(Rohm) BA511 9 pieces BA511A 3 pieces BA521 1 piece BA532 4 pieces

Sanyo LA4430 7 pieces LA4420 9 pieces LA4400 3 pieces LA4422 2 pieces LA4100 4 pieces LA4032 2 pieces LA4122 4 pieces LA4220 8 pieces
LA4140 4pieces LA4102 1 piece LA4182 1 piece

Hitachi HA1338 3 pieces HA1308 7 pieces HA1339A 5 pieces HA1306W 10 pieces HA1306P 2 pieces FA6013 2 pieces HA1366W 2 pieces
HA1366WR 2 pieces HA1368 1 piece HA1377 4 pieces

Panasonic AN7120 6 pieces AN315 6 pieces AN214Q 2 pieces AN7147N 1 piece AN630 1 piece MN2114 2 pieces M5115P 1 piece M5115PR 1 piece
M5109P 1 piece

Delco DA101 2 pieces DM31 1 piece DM11 1 piece DM44 1 piece DM32 4 pieces

Dolby NE545B 2 pieces

NEC upc1230H2 8 pieces upc1182H 4 pieces upc1181H 3 pieces upc1181H (board pulls) 4 pieces upc1025H 6 pieces upc1185H 4 pieces
upc575C2 11 pieces upc577H1 1 piece upc555H 1 piece upc554C 1 piece

ST Micro TDA1170N
TFK TDA1170N

Toshiba TA7205P 10 pieces TA7209P 2 pieces TA7201P 2 pieces TA7203P 1 piece

Fujitsu MB3731 1 piece

Mitsubishi M51513BL 3 pieces MB51514AL 7 pieces MB51515BL 3 pieces M51102L 1 piece

Few years ago I build Seas based speakers. (T25-001 and W17E-002). Speakers was my own design, even filter.

I was quite satisfied speakers sound to the moment when I get chance to listen original Jamo Concert 8 speakers. After that I was not satisfied anymore


So my question is that, does anybody have Jamo Concert 8 (Jamo D830) crossover schematic?

I have seen some pictures taken from that crossover board, but component values are not clear to me.

Picture shows how components are placed to board.
Red are capacitors, white are resistor and black circles are coils.

I got the proto of the s.e. trafo with multi tap
5 kohm, 43% and 20% UL
5 ohm single secondary
around 20H
primary wire 0,28 mm diam - Rdc 140 ohm
max Ia around 200mA
Pmax around 10 watt, column 40x45,
M3 - 0,3 mm. o.g.
4,4 kg




This is not available.

To play in the real world not in virtual
Testing some circuit.
Unfortunately I have to service now my Sofia ( some hard problem) then I can test the tube that will play in the circuit
proposed


Walter

The Iron Pre is now listed in the diyAudio store for anyone to purchase.

Until the 'Build Guide / Build Thread' is created, this post will contain all current schematics and notes for the Iron Pre sold through the diyAudio store. Check back frequently to ensure you have the latest files.

Sep 14 2023 - Below is what you're waiting for! See some awesome information and help from 6L6 on the SE build. A new thread and the guide using the web interface will be posted ... soon. Post #2291

Background

Hello Happy DIYers / Greedy Boyz!

I am thrilled to announce that Zen Mod's Iron Pre essentials kits will be offered in the DIYAudio store. This is not a group buy. You can learn more about the project in the thread linked below.

https://www.diyaudio.com/community/threads/whats-wrong-with-the-kiss-boy.293169/

Highlights include matched Toshiba JFETs from Nelson Pass and high-nickel CineMag transformers. 6L6 has volunteered to post one of his incredible build guides also.

If you're a Smiths fan, you may ask, How Soon Is Now? They should be available for order before the end of the year. At this time, we have enough parts sourced for 100 SE and 50 balanced kits.

The next obvious question is, how much? Costing is not final yet, but the goal is $100 for the SE kits and $125 for the balanced kits; a tremendous bargain. We have contingencies for all the parts, and we hope that this will be a permanent addition to the store. However, for now, we can only promise what we've got. Get 'em while you can.

Click the link below to see what will be included in the kit, answer a few questions about what you might like to see in the future, and get on the list.

Note - The n-channel JFETs will be 2SK370.

Quick and Dirty Startup Process

This happens after: the boards are stuffed, the AC supply is verified and connected properly, and I/O has been connected. Nothing needs to be shorted. Note the additional step for the V4 SMD version.

1. Set V+ and V-
   
   Adjust P1 and P2 for each board until V+ is +15V0 and V- is -15V0
   
   GND, V+ and V- pads are clearly marked on PCBs.
   Do not move forward if you cannot adjust the voltages to within 0V1 or if the voltage seems unstable.
   
   
2. For V4 SMD Only- Set current through JFETs
   • Set DMM to DCmV.
   • Place probes across R34 and R37 for SE or R40 and 41 for Balanced. You can also use square pads / test points near resistors.
   • Turn P4 and P6 respectively until DMM reads 14mV +- 0.05mV - See schematic.
3. Null DC offset
   • SE
     • No jumper caps in place for JP1 or JP2
     • Measure at center pin of JP1 and JP2 NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers for your choice of gain.
   • Balanced
     • No jumper caps on JP+ or JP-
     • Measure at pin 1 of JP+ and JP- NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers.​

Updates

4-May 2023

Edited 7-Aug 2023. All in-line photos have been removed. Please see attached files for all documentation.

5-May 2023

Updated Single-Ended BoM to correct 330R part notations in the gain stage to R28 and R29.

Attached are the Bill of Materials / Parts Lists - Note File Names for Balanced and SE

26 - May 2023

Updated SE and Balanced Bill of Materials to indicate that snubber components should not be installed.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v5.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v5.pdf

27 - May 2023

Updated SE and Balanced Bill of Materials to correct and clearly note which diodes should be installed for input switching.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v6.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v6.pdf

1 - June 2023

Note - No changes required. However, the packing lists some of you will receive may note LM336-5.0. That was a typo; apologies. The correct parts (as supplied and noted in the BoM) are LM336-2.5.

Removed the link to sign up indicating interest in kits. Those currently on the list will get first priority for the next round of kits. After that, they will be sold through the normal process through the store.

6 - June 2023

There are two gorgeous prototype chassis available; one designed specifically for SE, and one for Balanced. You can find some details in post #431. The depth for both chassis is 280mm. There is additional information sprinkled throughout the thread re: acceptable sizes and some potential part numbers for IECs, input / outputs etc. along with pictures of some examples. Please search first before asking chassis questions, and I'd recommend using the latest posts' information. Again, they are prototype chassis, and anything could change at any time until the design is finalized. The best source of information re: the chassis is directly from Modushop until they are sold in the diyAudio store. Timing TBD.

8 - June 2023

Added parts placement and pcb layouts for those interested.

30 - June 2023

V7 - Minor Updates to BoMs. QTY added. Ensure to check quantity per board against the quantity you need for your project. Added links to a popular online website to show examples of parts that will work for the connection between the main boards and the twister boards for input selection / LED power etc. Added generic descriptions for those that would prefer to select their own parts.

1 - July 2023

V8 - Minor Updates to BoMs. Added heatsinks for M3 if 12V relays are used.

7 - Aug 2023

I'm excited to say that more kits will be available very soon for 'round 2'. Continue checking this post (as always) and the thread overall for up to the minute updates.

In his graciousness, ZM has made some minor running changes. Changes are:

• Updated transformer snubber circuit.
• Easier positioning / mounting of the CineMag transformers in some situations.
• Changes to allow easier use of some logic circuits for input switching.

Boards that include the changes will note "2023" vs. "2021" on the silkscreen. The Twister board accompanying the 2023 boards notes V.3. Both 2021 and 2023 boards are included with 'round 2'. You cannot choose which you will receive, and you will not know which you will receive until they arrive. Do not fret if you get a kit with 2021 boards. If you need to use a particular type logic solution, there is a very easy modification previously noted in the thread, and the snubber is not necessary. The changes made were a kindness from ZM, but all 2021 boards can be made to function just like 2023 boards with a few user-tweaks described in the thread.

Note - The attachments have been packaged and note which files to choose for the respective boards. Previous attachments and in-line thumbnails / photos have been removed for clarity. The BoMs have been updated slightly for clarity.

9 - Aug 2023

There is a minor error on the silkscreen for the boards marked Iron Pre SE Zen Mod Labs 2023. The polarity notation for C11 visible when the cap is installed is incorrect. Ignore it.



13 - Aug 2023

His Mightiness created two graphics for how to wire standard pots for both SE and Balanced. Attached.

29 - Aug 2023

Minor updates to balanced BoMs. Removed reference to D15.

31 - Aug 2023

Added wiring diagram for AVC for SE. See post #2113 for context.

21 - June 2024

All testing for the Super Mega Deluxe version is complete. Kits will be back in the store 'soon'.

25 - September 2024

"Soon" is relative. 🙂. SMD kits are on sale. The schematics and files for the Super Mega Deluxe (SMD) have been attached in their appropriately named .zip files. Enjoy your builds.

26 - September 2024

A few people purchased the "completion" kits for the V3 and earlier boards and were wondering if they could be used for the V4 SMD kits. A lot of the parts are identical, but below is what you'll need in addition and to swap a few parts.

For balanced you will need:
4x additional 825R or 820R resistors - I like these Vishay BC 825R
8x 58R or 62R resistors - I like these Vishay BC 62R
4x 1R resistors - I like these Vishay BC 1R
8x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
4x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

For SE you will need:
2x additional 825R or 820R resistors - I like these Vishay BC 825R
4x 58R or 62R resistors - I like these Vishay BC 62R
2x 1R resistors - I like these Vishay BC 1R
4x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
2x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

27 - September 2024

Some potentially helpful additional parts in post #3784. If people have more helpful suggestions, I can add them.

3 - February 2025

Added diagrams for setting buffer current in V4 builds.

(For Mechano24 design with Scan Speak drivers click here LINK)
(For Mechano323 3-way design with AMT driver click here LINK)
(For Mechano23 design with Scan Speak and SB Acoustics drivers click here LINK)
(For Mechano325 7l 3-way design with Dayton drivers in "horizontal" arrangement click here LINK)


Mechano22
Not so long ago, I made a small 2-way speaker design with the following goals: f6 around 40Hz with 8 liters BR enclosure, generally balanced on-axis response and close to linear frequency power response.

Experience gathered with that design led me to a conclusion that maybe it could be done better and cheaper. And here is the new version, codemame "Mechano22".

It is based on relatively inexpensive set from Dayton: ND25FW-4 tweeter with waveguide and DS135-8 midwoofer.

Box dimensions: HxWxD: 290x174x260mm, made of 18mm birch plywood. The Box is filled with polyester fiber.

Both drivers are placed in the middle of the front panel, with centers 75mm (tweeter ) and 195mm (woofer ) from the top edge.

The woofer has a flat basket edge, which, according to the manufacturer's note, allows application without flush so it wasn't implemented. On the other hand, woofer mounting hole was chamfered on the inside.

Pic1. System on-axis and power response characteristics in comparison with target lines. For power response calculation +-180deg measurements were taken in H and V planes (10deg step):




Pic2. frequency response for DS135-8 (orange) and ND25FW-4 (gray):



Pic3. Crossover schematic:


Pic4. VituixCad, schematic and 6-pack for double check:



Pic5. Filters assembled on a scrap of plywood (for 1 unit):


Pic6. Units assembled (need sanding and waxing ):


Pic7. Measured on-axis dBspl (both units, 5dB/div). f6=40Hz if I did not messed up the measurements.


Pic8. Measured system impedance (both units).Nominal impedance is 6R (considering 5R minimum at 200Hz):


List of components used (for one unit):

Dayton Audio DMPC4.3 / 4.3 uF / 5% / 250 V / Polypropylene capacitor MKP
Capacitor Jantzen Audio CrossCap 0.47uF / 400VDC / 5% / MKP /
Dayton Audio DMPC8.2 / 8.2 uF / 5% / 250 V / MKP 2 pcs.
Capacitor Jantzen Audio Cross-Cap 9.1uF / 400VDC / 5% / MKP
Dayton Audio DMPC-2.7 / 2.7 uF / 5% / 250 V / MKP polypropylene capacitor /
Ty-Ohm ceramic resistor 22ohm / 22R0 / 20W 5% SQP
Ty-Ohm ceramic resistor 4.7ohm / 4R7 / 5W 5% SQP
Ty-Ohm ceramic resistor 100ohm / 100R0 / 5W 5% SQP
Ty-Ohm 12ohm / 12R0 / 5W 5% SQP
Jantzen Audio core coil 0.68mH / cylindrical / 0.162ohm / dr.1mm Fe 0.021kg / dia.20, length 40mm /
Jantzen Audio core coil 0.82mH / reel / 0.22ohm / dr 0.8mm Fe 0.056kg / dia.24 length 33mm /
Jantzen Audio Air coil 3.7mH / 3.25ohm / dr 0.5mm / dia.33, length 15mm
Jantzen Audio Air coil 2mH / 3.21ohm / dr 0.4mm / dia.31, length 8mm
Jantzen Audio air coil 0.12mH / 0.26ohm / dr 0.7mm / dia.27 length 8mm

Attached files: VituixCAD *.vxp and XMachina *.xmp with spinorama.

Good morning

I am building a clone of the SUGDEN A21 amp (class A) and want to associate a very good preamp with RIAA, tone control.
That of ELEKTOR 2012 caught my attention. To validate the quality of the PCBs manufactured by JLCPCB, I ordered the tone corrector part from them. Superb quality.

Now that I am sure I can have PCBs, I would like to have feedback from those built or use/used the Elekto Preamp 2012 or want to go in the same adventure than me!
So any feedback from this preampli would be appreciated, going to build it alone with no support is a bit hard.

Please let me/us know

Georges

I have a limited supply of these extremely low distortion NatSem ICs.

Common price, €10/each. + postage. Min 5 pcs, mixed ok.

Ships from Sweden, so no tax in EU.

R

Hi to all,

I just want to make a album for 15 songs time over 16 minutes. It's simple. Each user has to copy and paste adding only one song to the album so in the end it's 12 songs, one per user, and each album has to have a different theme.

Whoever adds the last song of the album gets to say what the the theme for the next album will be and it starts all over again.

Songs over 16 minutes:

1. Pink Floyd - Echoes (23:31)
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.

Hi all
I'm trying to design a 3-way speaker based on mid-range and tweeter I already have (used in a 2 way speaker some years ago).
I decided to add SB26SFCL38-8 to these 2 drivers in bass reflex configuration. The volume for the woofer will be around 88L with a resonant frequency is 27Hz.
I want create a cabinet with hard plywood 19mm with external size WxDxH 38x55x63 (the height is a constraint).
The cabinet will have a "small room" for the mid and tweeter of about 8L.
The port tube will have diameter of 9,2 cm and length of 22,5 cm
I have 2 main doubts now (may be more 🙂)
1. Where put the port tube. I have not enough space below the woofer do I would like to place it upper. Something like this...



I also did a try with 2 port of 6,6 cm and 24,5 cm length below the woofer.



What do you think is the best solution?

2. How many braces, where to place them and how shape them. I'm not so expert about this aspect.

Acoustic Horn Design – The Easy Way (Ath tool)

This is an associated thread for a waveguide generator called Ath (Advanced Transition Horn), version 4.
Ath is a piece of software for designing waveguides and horns. At the same time it makes it possible to easily simulate their acoustic behaviour by means of FEA (BEM) via ABEC/AKABAK tool.

The current Ath release is available at https://at-horns.eu





Thread milestones (last edited 26.12.2020, no longer maintained):

#233 Birth of the OS-SE formula
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#375 Measuring driver's exit wavefront
Acoustic Horn Design – The Easy Way (Ath4)

#666 Some of the practical verifications:
Acoustic Horn Design – The Easy Way (Ath4)

#844 Ath 4.4.1 - Introducing superformula
Acoustic Horn Design – The Easy Way (Ath4)

#922 JBL M2 "How-to"
Acoustic Horn Design – The Easy Way (Ath4)

#933 JBL M2 - Ath clone
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#1003 Comparison of an OS waveguide and a flat piston
Acoustic Horn Design – The Easy Way (Ath4)

#1117 Ath 4.4.3 released (Fusion 360 import)
Acoustic Horn Design – The Easy Way (Ath4)

#1533 Ath 4.5.0 released (scripts not backward compatible)
Acoustic Horn Design – The Easy Way (Ath4)

#1602 General phase-plug discussion
Acoustic Horn Design – The Easy Way (Ath4)

#2389 Joining profiles of different curvatures
Acoustic Horn Design – The Easy Way (Ath4)

#2494 Tritona Waveguide
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)


Spherical-wave phase plug

#1706 Initial ideas
Acoustic Horn Design – The Easy Way (Ath4)

#1824 Kessito's input
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#1892 Compression cavity modal analysis
Acoustic Horn Design – The Easy Way (Ath4)

#2016 Diaphragm suspension analysis
Acoustic Horn Design – The Easy Way (Ath4)


Free standing waveguides

#2600
Acoustic Horn Design – The Easy Way (Ath4)

#2936 Rolling back the profile
Acoustic Horn Design – The Easy Way (Ath4)

#3390 Employing axisymmetric BEM (finally)
Acoustic Horn Design – The Easy Way (Ath4)

#3427 Rollback added
Acoustic Horn Design – The Easy Way (Ath4)

#3532 Source amplitude shading
Acoustic Horn Design – The Easy Way (Ath4)

#3549 OS-SE formula extended: k
Acoustic Horn Design – The Easy Way (Ath4)

#3664 Effect of an enclosure and other parameters
Acoustic Horn Design – The Easy Way (Ath4)

#3822 Compression driver throat plug
Acoustic Horn Design – The Easy Way (Ath4)

#4186 Preferred in-room response and DI target (discussion)
Acoustic Horn Design – The Easy Way (Ath4)

#4503 Incorporating compression driver model
Acoustic Horn Design – The Easy Way (Ath4)

Morning all. I joined in hopes of finding drivers to refresh a Fischer & Fischer SL 1000 speaker built in 2000. I purchased the speakers used. I'm looking for Seas W17EX002 bass woofer preferably in black. Unfortunately, this particular Seas woofer is long out of production. The original speakers are in white, but I'm trying to redo the speakers in all black. If you happen to know the crossover points for these speakers, please let me know. Thanks.

Hi Everyone,
I`m an EE student, loved music since i was born. I`ve been on this forum for a while to gather info and ideas since there`s plenty. Have a great time.
Marco

ONLY 12 PAIRS LEFT. HURRY UP.

€80 FOR THE REST, REGISTERED SHIPPING INCLUDED.

I have a few hundred pairs for sale. As you can see they are quite old, the 2SA is green.

Also unopened plastic bags of 50 each. Not shown here.

Price $6/pair.

R

Onsemi announced that KSA1381ESTU is end of life with a last order date of Jan 5, 2025. Is there any interest in a group buy for these?

My thought is to combine it with a group buy of 2SC3503E which is available from Rochester Electronics (link here), but only in large quantities (1000+). This makes for a good pairing as KSC3503 is currently only available in D grade.

Lot sizes will be 100 pieces of each device.

As this would be a large cash outlay for the initial purchase, we'd probably need to have money up front. We'd have to backorder them as both Mouser and Digikey are currently out of stock, but accepting backorders. Maybe it'll arrive in time for Christmas.

I will keep the first post updated with anyone interested in participating.

PRICING UPDATE:

Pricing factors in the price to order, taxes, shipping and repacking materials with a bit of a bump so I don't hopefully loose money on this.

Round 1: $30/100. For example, 100 x 2SC3503E and 100 x KSA1381E would be $60 + shipping.

Round 2: $30/100 for 2SC3503E and $35/100 for KSA1381E. The higher price in round 2 for KSA1381E is due to a price hike on Mouser's end.

SHIPPING:
For shipping, US will be $5. International will be $20 if the quantity is 100/100. If over this, I'll PM an estimate. This is due to the weight threshold where international shipping prices increase.

VAT: If there is VAT in your country, I understand this will be collected from the recipient, not paid by me.

TIMING UPDATE:
The Mouser order for KSA1381ESTU has been placed. Its backordered at Mouser with a restock date of 11/11/2024 (if Mousers date is accurate).
Domestic orders arrive in the second half of November.
International orders will go out via USPS international which shows shipping times of 1 to 4 weeks.

PAYMENT:
I'll send payment info once I get close to being able to ship. I have PayPal and Venmo.

April 2025 UPDATE:
The Mouser order for KSA1381E failed to come through. Mouser canceled the order despite it being placed months ahead of the final order deadline. It's unclear if this is a Mouser or OnSemi issue. We looked extensively for alternate sources of KSA1381E but could not locate anything that was cost effective. It was determined that KEC KTA1381Y was the next best alternative.

April 20, 2025: Profusion order for KEC KTA1381Y placed.
April 25, 2025: Profusion order received
April 30, 2025: Estimated Ship Date for Round 1 order (for those that have paid)
Early May: Payment instructions to be sent for Round 2 participants

ROUND 1: Closed for new participants (Shipping April 30 ,2025)



ROUND 2: Closed for new participants (Shipping early May 2025)



ROUND 3: Open for new participants (based on available stock)

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

I have a rather large stock of NOS MOSFETs. New and used.

New are $20/pcs, used $15/pcs.

Ships from Sweden.

Thanks for looking.

R Malmin

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

I have for sale a number of these very low Cob Toshiba TO-126 transistors. They are of course original, NOS, and will only be sold Hfe matched. Y means Hfe 120-240.

€10/set. That is for one 2SA1360Y and one 2SC3423Y.

Shipping at cost.

R

I have been rebuilding a pair of Quad ESL-63s and am getting close to finishing. By rebuild, I mean I have reglued stators, and replaced diaphragms in all eight drivers.

I used Gorilla clear polyurethane glue to glue the stators of only one speaker- the other stators were bonded well and would probably have broken if I tried to break them loose.

I used 3 um mylar film, stretched using a pneumatic stretcher, with resonance tuned while the film was on the stretcher to about 92Hz. The diaphragms are glued using 4693H contact cement that unlike the factory glue, actually bonds to the grid and the diaphragm.

I applied Licron Crystal to the diaphragms and tested resistivity and resonance before and after applying the Licron. Resistivities all came out at either 10^8 or 10^9 Ohms/square. Resonance dropped by about 1 Hz with the added mass of the Licron Crystal. For those who might be concerned about longevity, I have some old drivers that I worked on in the early 90s that used 4693H and Licron coating, and they are still in good shape.







You can see details of my failed and successful methods on my blog page, here.

I'll be installing the drivers back into the speakers and testing with full bias applied over the next couple days.

Another, more powerful Woofer. Also - could I use a compression driver? I have these small speakers. For homework.

Hi all, I signed up here years ago, so I suppose that at some point it's time to say hello.

Hello.

This might be a silly question, but I've been wondering if there are any tips for listening to parts of a multi-way speaker individually?

I've been working on some multi-entry horn ideas, but want to test out various parts individually to get a feel for how they sound before commiting to a complete build around certain drivers.

It got me thinking of using an existing speaker and just EQing out the range of interest and then using it to "accompany" the driver in question.

Please let me know if anyone has ideas about this.

Hi
in attach the first proto of 300B OT with nano
It is 3k primary
5 ohm secondary (single)
Around 40H -100Hz but some adj with gap will be possible.
At the end it will be potted.
The first test are almost fine.






The Freq. answer; there is a little step at 50kHz, but it will be fixed
Zs are 700 ohm (blu) and 1 kohm (red)
At thr moment out of the power stage that will be ready soon



The phase

cancelled due an error

I recently acquired a set of Paradigm 11se Mk-1s from a friends dad. I've read a lot of great things about them but I think they suck. Of course everyone's opinion is going to be different but I think something is wrong with them but I don't know what. Let me explain....

These Paradigms are the ones with the Vifa DT19 tweeter, the Vifa D75 dome mid (the original gray dome) and the milky clear plastic 10" woofer (I'm assuming an Energy driver). Now I know these are often considered forward sounding, and I agree, but in every other respect they are worse then every other speaker I have. The largest of the issues is the dull, lifeless, anemic bass. And yes, they very likely have the original crossovers. I know these are early Paradigms, but a custom spec'd woofer in this big box, with three big ports? Even Chris Roemer's Nano Neo MT speakers have deeper and more powerful bass. [It sounds like I am talking about blown woofers maybe, but they do work and there is no distortion...]

In direct comparison to Energy Pro22 Reference Connoisseurs, the Energy's have a wider, taller, deeper sound stage, tighter imaging, and higher resolution. The 7" pro22 woofers have considerably more and deeper bass, with much more life and texture. My specific Pro22s have Solen caps in the crossover but I bet they are 15-20 years old.

The same impressions apply to my ADC 303x speakers (with brand new crossovers), though not as deep in the bass as the Pro22s. My newer speakers are significantly better then the Paradigm, but I just wanted to compare speakers from the same era. I've used tube and solidstate preamps and amps, even a tube/classD hybrid amp....same impressions. The Paradigms simply do not match up to any other speaker I own.

Normally I would just say they are not what I am looking for but everything I read on line in nearly every form suggests they should be at least equal if not better than the Reference Connoissurs.

So what do you think? Could the Paradigms be ranking so low just from the old crossover, or do you think they honestly are worse than the Pro22s and ADC303x's (with modern crossover parts)? Something else wrong with them?

[for reference, I appreciate a darker speaker with great soundstaging higher then tonality or analytical qualities. I listen to classic rock/modern rock/pop/classical at mid 90s db's]

Hello everyone,


I’m encountering an issue with my Pioneer PD-91 CD player. When it is flat, the disc doesn’t spin when I press "play," only a slight movement is visible. However, as soon as I place the player on its side (about a 45° angle), the disc starts spinning normally and playback works perfectly. Once the disc has started, I can place the player flat again, and it continues to work perfectly without any issues 😕.


I’ve cleaned the lens, but the problem persists. Could this indicate that the PWY 1004 laser is dead, or could it be another issue (spindle motor, alignment, clamp mechanism, etc.)?


I would love to hear if anyone has experienced a similar problem and if you have suggestions on any adjustments I could make to improve the situation. Are there any settings or simple repairs I could try before concluding that the laser is faulty?


Thank you in advance for any advice and feedback!

I saw a simple amplifier but thought maybe I can do it better without to many components.
Here is the result. Its not very temperature stable but in class A it gets less hot the louder you play.
So it is just to measure the current in the output transistors = voltage over R8 or R9 and adjust it with P1 to
a little more than Feed voltage / 4 * R speaker. But take half an Hour for the heat to be stable after the last adjustment.
It is easily adapted to other voltages and speaker impedances. Distortion is about 0,1% which maybe some people don't hear.
Noise is extremely low under 5 uv 20 - 20k. Common mode rejection is determined by C2. Frequency response is good 25 Hz to 95kHz -3dB.
View attachment 1418335


But looking at the results it is possible to do it much better. Faster and much lower distortion but a little more noise.
The problem now is that the P1 is very sensitive in adjusting the current.
Now the anti thump + radio interference filter on the input is included. But still pretty simple.
I changed the R12 to 0,82 ohm because I believe the IRF 540 has about 5S at about 1A.

I ran some tests with REW while waiting for the Scarlet 2i2 3rd.
On the Asus motherboard there is a 5.1 that I use in 2.1 (4front/modified) and on the subwoofer there is a 5" Vifa.
Here is the measurement of the card with this configuration.
How do you think?

Need help hooking up the main speaker system's remote.
rggl front rggl
rggl back rggl
Caution: floating grounds do not use with common ground system /What does this mean for me, hooking up four speakers?

Next is the main in /pre out front
back main in /pre out

2ch a,b both/4ch a,b and both
How to get them all to play on at once a b and a+b

tape 1___tape2
front and back
play and record
been working on this for weeks, think I got it, then I don't like the way it works, also some speakers don't work on a , b or both some speakers on sometimes, and then on with all
still have to find out how to hook up equalizer and subwoofer if I can to this old Planar XR4120 FOUR/2-channel BRIDGED RECEIVER????
I DO NOT KNOW HOW TO TRANSFER FROM ANDROID CELL TO THIS CHROMEBOOK SO NO PHOTOS UNLESS I CAN SEND TO MAIL OR SOMETHING

I want to buy 2 prasis crc pcb with lt4320.

Glad to finally be a part of this community, appreciate the wealth of knowledge on this site!

Hey I'm having trouble understanding exactly how I can control volume from my TV remote. I really wish TV's still had a volume controlled RCA analog output but here we are. I only have an optical out and HDMI ARC port. Is it possible to use one of those HDMI arc to analog audio converters so I can use the RCA output to my amplifier and control the volume with the TV's remote?

Which one of these caps is for the delay of the protection circuit? and what the other cap is for?

I'm looking for a schematic and any info for an 8 Channel Delco amplifier from an older Peterbuilt heavy truck. I think it may be the same as the older GM Monsoon systems used. It's an 8 channel amplifier with built in crossovers. It uses eight Delco 82452 chip amps. This one won't power up and the head unit is displaying "Check Amp Fuse".

I'm confused because I see microphones placed one meter away, and others only 20cm from the speaker.
And while we're at it, any advice on what to take to measure with quality.
the latest generation sound card, which should also be purchased, but I already have clearer ideas, will have the best features.
I just installed REW

I think Ronnie O'Sullivan has done the 147 snooker thing about 15 times. But this one was a particular goodie:

Login to view embedded media
Obviously raising his game with Reanne Evans. Like you would. But he did give her a fair chance! 🙂

The comments are achingly funny too. People who know how hard a 147 is. 😎

I've come up with an unusual amplifier topology involving boostrapped stuff, and that seems to have, shall we say... non-optimal clipping behavior. So it looks like I'm going to need a pre-clipping circuit.

Of course it should not distort at all until it does.

I've sketched a number of attempts, all involving bootstrapping the clipper diodes to reduce distortion by keeping voltage across them constant, which avoids nonlinear capacitance effects, leakage, etc. The bootstrap voltage is itself clipped by another pair of diodes, so when it reaches the limit, the other side of the diodes no longer follows the input signal and they begin doing their job.

The four ones on the left use diodes or transistors as diodes. They're strictly at the input of the amp, so they need an opamp buffer for the bootstrap voltage. The one on the right deletes the opamp by using the amp's output voltage (the power amp is VCVS E1) and using BJT emitter followers as diodes. Basically the two transistors' bases follow the input signal so they do nothing, until the diodes on the right conduct, at which point the transistors limit the input signal.

On the left is a sinewave with a smashed top.



And here is THD vs input level. Simulations are sometimes slightly optimistic, but it looks like "no distortion before it has to begin clipping" is achievable.



Thoughts?

VRDN: bipolar regulator PCB for line level ckts: ±11V to ±20V @ 1.5A with "De-Noiser"

A couple of diyAudio members and I perceived the need for a power supply board aimed at line level applications, such as for example Wayne's BA 2018 linestage. We felt it should include the following features:

• Rectifier diodes on board
• Transformer snubbers on board
• Usable with both dual-secondary and single-secondary transformers (AC-to-AC wall warts)
• True 1.5 ampere output capability, therefore: real heatsinks & big capacitors
• Output voltages field adjustable via multi-turn trimpots

The result is a PCB called "VRDN" - Voltage Regulator with De-Noiser technology. The DN technology was originally invented and published by Charles Wenzel, whose original article called it "Finesse" (link) . DN technology was greatly improved and expanded by diyAudio member Elvee, who named the improved circuit his "De-Noiser" (link) This regulator PCB implements De-Noiser circuitry, as shown in the schematic of Figure 1 below.

Capacitor C13, and everything to the right of C13, are the De-Noiser. Jumper block J3 allows you to easily disable the De-Noiser (jumper installed) or enable it (jumper removed). This gives the pleasant option of performing a before-and-after pair of tests, either with measuring equipment OR with human listeners. Try it one way, then try it the other. Which do YOU prefer?

The board includes two transformer secondary snubbers, namely (MOV1, C1, R1) and (MOV2, C2, R2). Metal Oxide Varistors perform double duty in these snubbers, serving as the across-the-secondary capacitance "Cx" and also acting as voltage clamps, if an AC mains spike or surge occurs. The values of snubbing resistors R1 and R2 were chosen after performing several Quasimodo tests on several different transformers, and I expect these resistor values will work well IN THIS PARTICULAR CIRCUIT, with a wide variety of different transformers. However, if you wish to perform your own Quasimodo tests on your own transformer, and derive your own optimum values for R1 and R2, please go right ahead with my blessings and good wishes. Just remember to insert your actual MOV1 component into your Quasimodo's "Cx" socket.

Figure 1 includes two bridge rectifier components, BR1 and BR2. Each of these implements a "Full Wave" rectifier, meaning it transfers energy from the AC mains to the DC filter capacitors, two times per cycle: once at the peak of the mains sine wave, and once at the trough. The circuit contains two Full Wave rectifiers, one per transformer secondary. One of them produces the positive DC voltage output, and the other produces the negative DC voltage output.

However, when conceiving this board, we envisioned that some hobbyists might wish to build a bipolar regulated supply but feed it from an AC-to-AC wall wart instead. This has the great advantage that it keeps the mains voltage completely away from the DIY chassis; instead of 115VAC or 230VAC, the wires which enter the chassis carry only 16VAC or 18VAC, which is noticeably less dangerous. An AC-to-AC wall wart also allows a smaller DIY chassis with less interior volume, since the transformer is now outside rather than inside the chassis. But an AC wall wart is just a transformer with a single secondary.

VRDN implements the conventional, textbook method for creating a bipolar DC supply from a single secondary transformer. It's called a "Half Wave" rectifier, and as the name suggests, it transfers energy from the AC mains to the DC filter capacitors, only one time per cycle: either at the peak, or the trough, of the mains sine wave. One HWR generates the positive DC voltage output, and the other HWR generates the negative DC voltage output. Exactly as is done in the Objective-2 headphone amplifier, among MANY other examples.

To use the VRDN board with a single secondary, AC-to-AC wall wart, we need to make a few very minor adjustments. They are tabulated in Figure 2 below. As you can see, the only changes are to the list of stuff-and-solder actions. No PCB tracks need to be cut, no soldermask needs to be scraped off. You simply do-not-stuff six components, add three jumper wires (each 2.5mm long) into pre-labeled locations, and stuff two discrete diodes into existing & labeled thru-holes. It's easy.

Figure 3 shows two VRDN boards. The top PCB in the photo is configured for a dual secondary transformer -- notice it has two green Euroblok connectors at the left edge of the board. One connector for each secondary. The bottom board is configured for a single secondary AC-to-AC wall wart. It has only one Euroblok connector and only one snubber at the left edge of the board. Everything else on the two boards is identical.

Figure 4 is a detailed picture of the input circuitry, on a PCB configured for two secondaries. Again notice the two Euroblok connectors.

Figure 5 is a detailed picture of the same region, this time on a PCB configured for a single secondary AC-to-AC wall wart. You can see that the bridge rectifiers are not stuffed, the (MOV2, C2, R2) snubber is not stuffed, and the Euroblok connector is not stuffed. You can also see that the three jumper wires "JOR1, JOR2, JOR3" have been stuffed -- look for pink arrows on the photo. Discrete Schottky diodes (5 amperes, 100 volts rated) have been stuffed -- look for gold stars. One diode is stuffed in holes "A" and "C", the other diode is stuffed in holes "L" and "M". Exactly as required by the options table shown in Figure 2.

The Jumper Options are shown on the schematic as 22 megohm resistors. This is a limitation of the CAD system and, specifically, a limitation of the CAD system USER, namely me. In truth, in real life, on your real PCB, JOR1 is either a zero ohm resistor (i.e. a piece of 22AWG hookup wire with white insulation) or else it is an INFINITY ohm resistor (i.e. an open circuit; nothing stuffed). Same goes for JOR2 and JOR3. Completely disregard "22 megohms" on the schematic. Ignore it. Pay it no attention. Simply remember that JOR1-3 are either opens or shorts. Opens or shorts. Repeat after me: opens or shorts. Look at the photos in Figures 4 and 5. Those options are either not-stuffed-at-all (open) or else stuffed with hookup wire (shorts). You can see them right in the photographs. Repeat after me: opens or shorts.

Figure 6 is a photograph of the output side of the PCB. Individual wire-to-board connections are provided for supply and ground, for each of two stereo channels. Also visible in this photograph are the vertically mounted resistors. This PCB uses the vertical orientation exclusively. Finally if you look very closely, you can see the amber colored Kapton tape on the back of the heatsinks.

TIPS FOR BUILDERS

Please carefully study the top silkscreen text layer when stuffing and soldering the 1N4004 diodes and the 1N4148 diodes. There is a little "A" next to each hole where an Anode is soldered. You'll find that on every 1N4004 and 1N4148, the cathode (band end) of the diode is the short wire which is stuffed straight thru the PCB with no bends; the cathode is the "butt end" of the vertical diode. The anode wire is the one which is bent into a 180 degree U-Turn, and is exposed for easy probing. The anode wire goes into the PCB hole with the little letter "A" on silkscreen.

First stuff and solder all resistors and axial diodes. Second, stuff and solder the MOVs and the bridge rectifiers (if using!!). Third, stuff and solder the Euroblok connectors and the two pin headers J3 and J4. Fourth, stuff and solder the small (non 2200uF) capacitors, the trimmer pots, and the transistors. Fifth, stuff the regulators-on-heatsinks (next paragraph).

After you bolt the LM317 and LM337 to their heatsinks, including the Sil-Pad insulator and the insulated shoulder washer / bushing, I recommend that you test-fit one of them into the PCB. You will discover that your unmodified assemby doesn't quite fit! You'll need to modify it. Bend the leads of the TO-220, backwards (towards the heatsink) about 1-2 millimeters. Try this. Aha! Now it fits. Put a piece of Kapton insulating tape on the back of each heatsink, over the TO-220 mounting bolt. The two heatsinks are positioned back-to-back and we don't want them to come into electrical contact. Kapton tape prevents that.

Stuff the regulators-on-heatsinks so the heatsink edges are flush with the PCB, but only solder the IC legs for now. Do not solder the heatsink mounting pins yet. Instead, turn the board right side up and look at the heatsinks placed back to back. You want to see a nice wide air gap between the two heatsinks, about 3-6 millimeters wide. When building my boards, I folded a sheet of paper in half, and half again, and again, etc., until I had a bundle 5mm thick. Then I jammed this paper bundle down between the two heatsinks to create a definite gap between them. With the paper in place, enforcing a nice gap, THEN I soldered the four heatsink mounting pins in place. After the solder joints cooled, I removed the paper bundle and voila! A nice, permanent, air gap between the two heatsinks.

Finally, stuff and solder the twelve 2200 microfarad capacitors.

SUMMARY OF FEATURES AND MIS-FEATURES

• De-Noiser circuit with jumper enable/disable
• Diodes on PCB
• Transformer Snubbers on PCB
• Big capacitors on PCB allowing true 1.5A output
• No bleeder resistors on PCB
• Voltage regulator ICs mounted on heatsinks for true 1.5A output
• Heatsink thermal resistance is 8.6 deg C per watt
• This is a four layer PCB, three of which are ground planes
• Gerber CAD files freely available, send to any fab you wish
• No "pilot light" LEDs on DC outputs
• Can use with either dual secondary trafo or AC-to-AC wall wart
• No SMD components; 100% thru-hole
• PCB unique identifier is TZPTR7 ; suffix -A means "revision A"
• PCB mounting holes compatible with Modushop chassis baseplate
• Board size 62 x 142 mm (edges) ; 50 x 130 mm (holes)

NEW INFORMATION

• 2023-12-21: a Forum member has created a new PCB layout of VRDN with only two layers. He has made the Gerber files freely downloadable in (this thread). Be sure to read his Disclaimer and non-Guarantee at the bottom of post #1.

Hello guys, I wanted to share my last build, maybe get some feedback.

I was very happy with my nupole (nude dipole on a pole).
Took the dipole path few years ago, for a very evolutive and iterative process with 20+ versions.
The last one was very very satisfying, but I couldn't stop thinking that it might all be based on biases that evolved in parallel.
Friends and even more Hifi enlighten friends enjoyed it too but could not invalidate my choices.
Also the room evolved with the build, and I know this could hurt the end result, or know that I might have to change few things to better work with a box system, but this is for later.

So I decided to try one last time a boxed system.
I initially started with a simple 3 way sealed, classic look that I like, reasonable size as I thought I wouldn't need much SPL.
First prototype was not very pleasant.
Build a second one a little bigger, not much better.
It felt weak, not enough presence in the room, no filling/no feeling.
I'm sure it could have been better with a lot of tune work but it was just not a good enough starting point.

So, for the time and money involved why not go nuts with the biggest I could fit in the room?
Always love the jbl 4350 serie, so this was the first inspiration.
And really love the Pitt & Giblin stuff, this was the kick in the back I needed to decide for a 3 way sealed with horns.

In the same time Nicolas opened his online shop on Audio Horn so after discussion I went with the X-28 with roundover option.
2x15" woofer sealed for the bottom to try sub-less first, and allow a future port if needed.
Studied a bit what kind of woofers could play nice in a sealed box of 100L, at reasonable prices, and went for the SB 15OB350 (very cheap and the simulated response was not much better with the 15SW800).
Then what kind of midrange could play nice between 200-1500Hz with this horn? The PHL3040 seemed a good fit, among others.
I could have gone with a more low midrange oriented one but wanted to try.


Construction was fun, I'm very impatient and usually start with minimal plans, my way to deal with surprises during the process.
Very useful informations were found online around the jbl : plans, clones, video build etc so I had a good idea how to do it.
I also have a limited wood work knowledge, practice and tools, so I again went the ikea route, for a good enough finish with minimal work.
So I took some door panels, full particle boards with a fake but nice walnut finish, for the outer box, and Eket boxes resized for the horns.
22mm plywood for front and back, with mdf as second layer where needed + bracing.
100x70x40cm, 280L outside and around 220-230L inside, with a 15L. box for the midrange, bracing very similar to the the jbl, all panels in their longer length + support around the woofers. Kind of light bracing as a start, that could evolve if needed.

Bought few tools to get a nicer result, a little router that was very easy to manage and surprisingly strong enough for the big holes, and a plunge saw with rails for better cuts as my regular circular one didn't cut straight on longer runs.

I've built one at a time and was ready for 3 thinking I will mess the 1st too much, but fortunately it was ok and I was able to do 2 very similar in a row. The second one is a little cleaner on edge cuts and details but is 95% the same I'd say.
To do better I would have to study real wood working, or ask for help.
It sure could be built better but it is solid, where I thought it seemed a little weak I would just add some wood.
If I redo one I would go even bigger as finally their size is fine.

Few pics of the boxes:








And some of last rew stuff:

- Nearfield response per driver, no eq needed on the midrange, big +12db boost on the woofers.
Did a bunch of off-axis measurement to get a feeling of the response, not shared here I just don't always save them and almost never "tag" them anyway.
Planned for a 1200ish Hz crossover for the horn, but surprisingly the 10" midrange off axis response was too good high up, or not enough directive if I can say to get a good match with the horn, so went with 1400Hz.




- Sum and timing made at listening point with mic and ears, before and after eq with averages:




I first heavily stuffed them but at the end removed everything. Clearly lost 4-5db with stuff above 50hz for just a little more low end.
And without, compensated by eq, it just sounds better.
I didin't notice much resonance, nor saw any in the impedance sweeps, just something to check for later.
Still working on the tuning of course, the first result was disappointing on the low end, I clearly missed the clarity of the dipole stuff.
It really felt like I missed some notes! Or the room just ate them.
I tried to integrate the H-frame subs, but this was nearly impossible, placement and room interaction just didn't work to mix both types.

I don't listen super loud so I have headroom with the woofers, that's why I pushed them a lot.
And after few more tunes it got better, I was able to get back some of the presence the first octave can give you.
But sure the room is not forgiving, work in progress…

The horn is really good, of course it gave me more precision in the soundstage, more than the dipole.
So a little more accurate, easier on listening window too, but also less ambiance. It's just too early to judge.
Nothing to say on the midrange, it does its job perfectly, and very efficient too.
They might not be as good as the kartesian, but here it's also too early to judge.
It's the very beginning and there's a lot more to do and test. different crossover points, different slopes etc.
The target is hard to adjust, I need more time as it's a very different result.
Also one day I might measure them outside and try Virtuix, but they're damn heavy…


I re-used the flex 8 and some of previous amps at first.
A Schiit rekkr for the horns, perfect, absolutely silent!
A fosi v3 stereo with 36v for the midrange, lowered the volume but it's still a little hissy.
And Crown xls 1502 for the woofers since the boost needs some power.

I initially though about getting some plate amps, fusion maybe for an integrated look, and to get power for the woofers.
But I also had not so good experience with hypex and HE drivers, so I first took some voltage measurements on the cones to see what kind of power they used.

• dual parallel woofers, 3.6 ohms at 30hz where EQ boost is severe: at -20db on flex, 2.8 watts and at -10db, where I just almost never go: 28 watts. So far off the Xmax limit around 500w even at max volume.
• midrange at 1Khz, peak of the response: -20db 0.025 watts, -10db 0.25 watts

Very efficient, so finally and since I don't think I'll ever go over -6db I ordered a second rekkr to put on the midranges, I'm confident they will be then totally silent.
For the woofers the xls is too noisy, tried the little fosi v3 with 48v and it's better, but I think their new v3 mono will be a better match, waiting for them now. Glad I didn't ordered the fusions!


So now I enjoy the new sound, it's different, but the more I tune the closer it gets.
I don't think I will get he clarity of the dipole, but I will just have to decide it I can accept the new compromise.
If ok I will then finish them a little better, paint the baffle, adjust few things, and then start to adapt the room, relocating the diffusors for example.
If convinced I could even rebuild them better, bigger.
One thing for sure, they will be easier to live with as I don't have big powerplants in the middle of the room anymore, better when receiving a bunch of people during summer.
Cats enjoyed them too, they don't care about the cones and I'm glad, just two more big things to climb on and chill 😉

I have a Quad99 system, with AE speakers, which yields a sound akin to analogue and I love it. Unfortunately, the CDs have started to skip after a minute: everything is fine, then it stops and the display goes ape with numbers randomly flashing on the screen. I suspect the laser lens is playing up. I use a CD lens cleaner but it obviously is not man enough to do the necessary. So, do I buy a new CD lens cleaner, or open the CD player up and try to give it a good clean (compressed air? vacuum?). Or, as it seems to work fine for a minute, could the laser lens transport be at fault? If so, how can I confirm?
Has anyone had a similar experience? How easy is it to get inside a Quad99 CD player? Any suggestions???
Cheers

Hello everyone,

I’m working on designing a Class H audio amplifier with a power output of 2000W RMS at 4Ω load, and I need some guidance from experienced designers.

I've previously designed a a 800W RMS Class AB amplifier for outdoor applications. Now, I want to develop a high-efficiency Class H amplifier for professional audio use.

Key Requirements:​

✅ Output Power: 2000W RMS @ 4Ω
✅ Topology: Class H with multiple rail switching
✅ High Efficiency & Low Distortion
✅ Stable Power Supply Design
✅ Thermal Management & Protection Circuits

I’d appreciate any insights on:
🔹 Proper rail voltage selection for efficient power switching
🔹 Best MOSFETs/BJTs for high power handling
🔹 Reliable protection circuits (Overcurrent, DC, thermal, SOA protection)
🔹 PCB layout guidelines to minimize noise and EMI
🔹 Any reference schematics, simulations, or design resources

If you have experience in designing high-power Class H amplifiers, I’d love to hear your advice! Feel free to drop suggestions, references, or even share your past projects.

Thanks in advance! 😊🎛️🔊

The Mission 778X is based around the design of the Quad Vena II and Leak Stereo 130 which both use the LM3886 as far as I know. Looking at internal pics I can see 6 forward pins on those two but the 778X has 8 forward pins so maybe a TDA7293? Specifications are similar for all the amps and are made in the same IAG factory. I assume when the 778X was designed, the LM3886 supply issues came into play.

I can't see enough through the vent holes and as it's new I do not want to remove the cover as well I do not have a Torx bit small enough.

Looking for a NOS pair, ideally in the UK or Europe.

Hi Folks,

I'm not an expert on SPDIF nor transmission lines, so bear with me please!

Background:
My good old well working Audio DSP has a digital output port with CS8420 feeding a AES3 (with TXP & TXN) and a Cinch (75Ohm) Output (with TXP) in parallel at Pin26.
The picture "original" shows the output schematic as far as I could analyse the (4-layer) board (pretty obviously with supply and GND layers). GND on the board is split between the output connector area and the circuit area (for unknown reasons) bridged with 0Ohm parts.

My Plan and request for confirmation or advice what to do:
The DSP is planned to drive 5m/15ft long koax stereo SPDIF BNC connections to each of my stereo speakers sporting digital 4-way "mono" x-overs. I.e. whether the speaker is "left" or "right" is selectable in the speaker. So, basically I need two parallel BNC Outs (would remove the cinch connector and disconnecting AES3 circuitry).

Please kindly have a look at the schematics and options I have come up with. I am sure my stuff needs changes to work properly, so I would be very grateful for recommendations "how to do this right".



Thanks a lot for reading all this and I hope you care to answer with any helpful recommendations.
Regards,
Winfried

Looking for 1pcs 2sk60 rank 5 or 6.
Can also trade for ...i have 100pcs 2sk170, some Black Gates, good European triodes, new in box ecc82 Telefunken, e88cc, ecc83, 3pcs rda1541
I have also 1 set of D3 tda1541 boards with 50% ,parts.
Maybe chinese board heavy modified es9038q2m with first generation Bisesik nanocrystalinev output transformers hi-fi tunimg silver gold 10A fuse new in box.
Thank you.

Offered here, for your consideration, an original prototype FirstWatt F6. Built and sold at auction in support of Burning Amp by Papa in 2023.

This amp is of the original design configuration that used SemiSouth JFETs, not the MOSFETs that the commercial F6 used. Note the dual LEDs on the front. I have no proof but I believe Papa assembled this himself. The amp was opened and pictures taken at BA that year, I have not opened it nor messed with it or put it on any test gear, but I have listened to it lots in my main system. There is nothing at all wrong with this amp. To my ears, and in my system, it is the most detailed amp I have heard, but for some mysterious reason I favor the air and liveliness of my F5m and Aleph Jzm more.

I paid $2600. I am asking $2600, plus shipping to your locale (it will come in the factory original shipping box). If you happen to reside in Northern California, I'm open to arranging a pickup but please be patient with me as I work for a living and have some travel coming up. This isn't about the money, it's not a forced sale, I'm not in a hurry, no low ballers, I know what I've got, etc., etc. I've just listened to this amp enough to learn from it and I'm willing to pass (haha! Pass) it on to another aficionado.

Thanks for looking.

First, forgive me that I have not posted here in ages. I'm looking for help with my much loved Threshold FET ten/hl preamp. In my system the outputs of the FET ten/hl are connected to a homebrew converter using Jensen JT-6110K-B 4:1 stepdown line input transformers. The balanced outputs from my transformer box feed a pair of Schiit Tyr monoblocks.

The problem is I have been measuring about a 5 dB drop off from 40 Hz to 20,000 Hz at the outputs of the Tyrs.. My first thought was the problem might be caused by excess capacitance in the cables running from the transformer box. I swapped out cables. I removed the transformer box. I swapped out a lot of things. The only thing that fixed the drop off problem was disconnecting the FET ten/hl and putting in a different preamp. Nothing else made any difference.

Would anyone have thoughts or suggestions?

Lot of updates have happened. Version 2.0 PCB has been made and group buy completed. All PCBs sold, but if you want one, PM me.

Latest schematic and build docs
Test PCB Image
Power up procedure
Distortion measurements
Gain calculations
Part I Upgrade to original design
_____________________
Original Post

Introducing the Schade Common Gate (SCG) Preamp. Signal comes in at the bottom source follower (unity voltage gain) and is then amplified by the Schade-enabled top MOSFET operated in a common gate configuration. This gets around the problem of low impedance on the gate of the Schade device.


Note: the schematics and information presented here is for personal and DIY use only and NOT for commercial use. Any other use needs my permission.

Inspiration came from George (tubelab) and Smoking-Amp, who were exploring the source-follower to common gate configuration for tube pentodes. I made a comment here that you could do this with MOSFETs too. Wrenchone and others have explored the Schade idea and Papa himself posted that really elegant Schade-enabled amplifier where the feedback connection is on the primary of the transformer to get around the problem of input impedance. I really like simplicity and elegance this circuit provides.

Here’s some of the pros of this approach:

• Gain device operates in triode mode.
• Low parts count.
• No unobtanium transistors or tubes.
• Low cost.
• No cap on the input.
• High input impedance and low output impedance (though I haven’t measured this yet).
• Preserves the phase: the source follow and common gate stages both preserve phase.

I built the resistor-loaded circuit and also a CCS loaded one (next post). It sounds excellent. It has the negative phase H2 (blue goes down when red goes up and blue goes down when red goes down), which really brings out the magic. Over the past couple of weeks, I’ve compared it to my other preamps, the 801a and the LuminAria, and it is comparable in sound.

Here are some measurements of the resistor-loaded version. I haven’t played with the load line much, but raising the load from 500R to 1k does improve things. The CCS version has almost no distortion. Subjectively though, I prefer the resistor-loaded version, it has much more of that 3D and “live” sound of LuminAria.

The build is a rats nest right now. Used the existing LuminAria setup with the Salas shunt reg. Hope to put it in its own box.

I've recently came across a new cheap little component tester that does way more than just the usual few basic tests.



This little beauty also can do basic DSO functions and is also reasonably accurate. There's also a signal generator and a full set of electronic diagnostic testing, including cap leakage/ESR, full inductor parameters and decoding IR remote waveforms, automatic pinout recognition of just about any device, including IGBTs, SCRs, diacs, triacs, all sorts of diode types, etc etc etc.

It run off an internal battery rechargeable through USBC and includes cables,, probes and connectors. The menus are very easy to navigate through and most tests are done very quickly. I've been trying to find specific devices it doesn't recognize or can't test. So far I haven't come across any (excluding ICs, but it will detect some lower voltage 3 pin Vregs!)

The best part is this tester is that its quite accurate and only costs $43!!!

looking at building some pensil type speakers, and at the moment don't have the drivers called for in any of the designs. Is there some rule of thumb that I can use to modify the box dimensions to get close enough to re-size the box to drivers I do have?

Drivers I want to try currently are Mark Audio CHN-70. There will be others soon enough, I'm sure.

I have modeled a few of the various published boxes in CAD (I use fusion 360), so that I could figure out the net volume (not including the driver), and have not really figured out what speaker parameters are the cause for a bigger or smaller box. I'm guessing the Fo, and the Qts are the more important numbers, but also the Vas?

pensil R70.3 has a volume of 2124 in3, pensil p70.2 has 2098 in3 - Not a huge difference. The original pensil R70 had 1792 in3 and the p70 had 2303 in3 volumes. I have not found the specs on those drivers yet to compare. of the currently available drivers with parameters listed online, the CHN-70 look closest in t/s parameters to the CHP-70 gen 2, though they have slightly lower Qts, larger Vas, smaller magnet, and lighter cone. I could try a box built to the same size as called for in the P70.2, but if I knew how to adjust these properly, it might save a bunch of trouble.


I'm also curious about bracing on these boxes. They don't seem really big enough to need it, but the plans say to refer to how the super pensil is braced, which is easy enough to follow. What I'm not sure about it whether I should keep the overall volume inside the same with the bracing, or increase it based on how much space the bracing takes up.


I have hornresp on my computer, but haven't quite figured out the ins and outs of getting useful information from it yet. I'll mess around with it some more and see if I can figure out how to input models of this kind of speaker (this is a mass loaded transmission line?).

Hi everyone, I'm a new member so let me tell you why I'm here! Since last year I started collecting vinyls and eventually found myself getting into audio equipment but I'm new to this, never really made any repairs myself. I know the basic of electronic but it's all text book, never really tried it out in real life.

For now I want to work on amplifiers mainly for turntables that I found in thrift stores or on marketplace.

That's it, lets see where this goes! 🙂

Hi everyone

I've been working professionally with solid state amplifiers for over 3 decades , and have been surprised by the sudden surge of devices going EOL. I believe that traditional class AB amplifiers are not going away, but are transitioning away from the mainstream to a boutique market. Valve amplifiers saw this happen a long time ago. With that said, there are a lot of high end solid state amps being built, and specialized parts sources are out there to supply them. I would like to list a number of sought after device type easily available, in some cases with a different part number.
They are available from Profusion plc in the UK. We have verified samples of everything listed here in pro audio gear made by LAR audio systems.
LAR audio is reason I had to locate some new sources.

KEC DEVICES (Korea Electronics Corp.):

KTA1381 / KTC3503 300V FAST VAS STAGE TO126 Replacement for the EOL ON devices really fast high voltage VAS
They should be in stock by Jan.

KTA1837 / KTC4793 230V VAS / DRIVER TO220 Replacement for toshiba 2SA1837 / 2SC4793 , good VAS and driver , in stock

KTA1700 / KTC2800 160V VAS / DRIVER TO126 Replacement for 2SA1220A / 2SC2690A , GOOD VAS and driver in TO-126
They should be in stock in Jan

KTB2640G / KTD1640G 150V 130W FAST DARLINGTON OUTPUT TO3P N Replacement for Sanken 2SB1647 / 2SD2560 improved SOA, in stock
This is a really nice output device for simple hifi amps

KTA1943A / KTC5200A 230V 150W WIDE SOA FAST OUTPUT TO3P L (TO264) This is an enhanced version of Toshiba devices, almost identical to 2SA1302 / 2SC3281 in every way , but higher voltage rating.

Unisonic This is not the most serious sounding name for semiconductors, but it is an established OEM supplier in Taiwan.

2SD669/A / 2SB649/A The TO126 versions are a good substitue for 2SA1220A / 2SC2690A There is some confusion about power ratings on the data sheets because they come various packages, including SMD, and the rated power is in free air We have verified that the SOA curves for the 2SD669A apply to all TO126 devices when on a heatsink.

2SA1837 / 2SC4793 The TO220 versions are also like the old favorite, but they are available in various case styles.

I may have post this in the wrong area, but searching threads, most appeared to discuss a specific need for a specific project. I hope I have been helpful to continue on with the construction of fine Transistor amplifiers.

Six months ago, I bought a second-hand DUNTECH Sovereign 2001 to fulfill a dream from my youth. However, its sound disappointed me, so I decided to modify it. After two months of research, the first step I took was to replace the original DA 30W100 06 subwoofers with Scan 30W/T4558T00, the DA 17W75 06 woofers with Scan 15W/8531K00, and the Scan D2010 tweeters with Scan D2104/71200. Since I couldn’t find an ideal replacement for the midrange drivers, I left them unchanged for now.

The second step was to remove the original passive crossover and install a custom 4-way speaker input panel, moving toward a fully digital 4-way active crossover setup. I'm using the ZIDOO UHD8000 streamer, which allows digital volume control on the SPDIF output, feeding directly into the Accuphase DF-45, then into power amplifier and speakers; no need for preamplifier. This ensures a clean and transparent signal path. The next step is to fine-tune everything using SMAART V8.( I had used SMAART since V3; the Floppy Disc era)

PS: The SCAN drivers for SUB and LOW cannot be directly mounted to the screw holes of the original DA drivers on baffle of Sovereign 2001. Custom-designed and 3D-printed adapter rings are required to fit them onto the existing DA mounting holes on baffle of Sovereign 2001.


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How about this to start it off ?

The Class-A Amplifier Site - JLH Headphone Amplifiers

Hello noob question here.
If a schematic for a tube amp calls for a 300-0-300@ 200ma can a 300-0-300@390ma be used or will the extra ma's cause problems?

Hello,

I have bought a used pair of the McCauley 6174 quite some time ago, and did my best to use them in an open baffle configuration (with limited success...).

But now it's time to finally put them where they belong, into a vented box. I use Unibox by Kristian Ougaard for the calculations, the ideal size would be a bit over 500 Liters... but that's a bit more than I can fit! I played around a bit with the values and ended up with a 300 Liter box with 261 Liter internal volume (deducting driver and bracing), tuned to 20 Hz, F3 should be at roughly 30 Hz (if I did this all correctly):



And here is a rendering of what it should end up looking like:



Here the baffle and bracing only:


And I hear some readers screaming "what, OSB?".

Well, to be honest, I have my doubts about that idea now. I just happen to have a bunch of it left-over at the moment. The baffle is cut from an old but nice and strong oak-veneered 3/4" plywood, it's already being glued up to the bracing:



No OSB has been used yet, so still time to re-think. When I read about gluing OSB, I found a few people saying it doesn't glue well with wood glue. One point against using OSB. Further I just think that going through all this effort building the speaker (two, actually), why not spend another 150 Euros and use some Plywood for the rest instead?

I'd love to hear your thoughts on that, and any other thoughts of course as well!

P.S.: The vented port is still missing in the drawings.

Many people say that dome midrange drivers have a sound quality which is unique and desirable. I have heard systems with dome mids that sounded very good, and others which were very ordinary. This thread discusses this topic in detail....link

For the past year, I have been thinking about the Bliesma M74A-6 driver, and simulating various options to use it effectively. To me, this driver offers an excellent way to experience the power and potential of a good dome mid in a high performance application. I like that it operates pistonically over its full range, and the first mode resonance is more than an octave above its likely pass band. This feature sets it apart from its silk and paper dome sisters. I like that it has high sensitivity and high SPL capability. I like that @HiFiCompass has measured very low harmonic and modulation distortion at high SPL. I like that the “A” aluminum dome version is considerably less expensive than the beryllium and textreme versions.

Thus, I started this project with just one primary requirement, that it use the M74A driver.

Index

I was reading about SLAPS Passive Radiators. Please see attached SLAPS_manual_ENG.pdf. It just has two back to back attached surrounds sharing same PR disk mass.
Attached are front, side and rear images of SLAPS PR, the slots on one surround are just to avoid air compression during operation which will otherwise damp the movement, for our discussion, the slots can be ignored and we can assume that there are two back to back surrounds without these slots.

One effect I immediately see is that this SLAPS will increase effective stiffness of the PR as each surround is bringing its own stiffness. I assume that we can punch in the numbers in a PR simulation program like Unibox and generate the frequency response of the system.

However, I was surprised to read SLAPS_manual_ENG.pdf and found some things deviating from usual theory of PR working and I have listed down only those points below. Can we have a discussion on each point to either accept it as mentioned in SLAPS_manual_ENG.pdf or dismiss it as gimmick? I have also mentioned my understanding for each of the point below in italics.

1) Claim: The revolutionary efficiency and performance are the result of the pneumatic coupling between SLAPS and the active driver.
Wait, 'pneumatic coupling'? I thought this supposed pneumatic coupling was also valid with a normal PR, how does that suddenly improve with SLAPS?

2) Claim: The unique design allows the active driver compression-free movement resulting in deep, dynamic and hard-hitting bass response.
In case of normal PR, the PR size is one greater than active driver, for eg for 12" active driver, a 15" PR is recommended so that we dont get xmax related compression. Whats so different with SLAPS?

3) Claim: Conventional computer modeling software will not work correctly with SLAPS and will in most cases greatly overestimate the internal volume of the optimal cabinet.
Why does double surround PR break simulation?

4) Claim: SLAPS increases a subwoofer efficiency and capability for ultra low frequency reproduction (very deep Sub-bass) without the drawbacks of traditional designs.
So, I read the patent and attached the PR excursion vs frequency plot from the patent, as you can see they show more extension for SLAPS and a steep fall response for normal PR, why this difference in bass extension between both?

5) Claim: It gives you much better performance due to the increased surface area and the fact that the particles of air
inside the enclosure and outside the cabinet moves with the same speed and in a near phase relationship. Phase means that the active device and SLAP work almost concurrently and simultaneously creates respectively pressure and counter-pressure at the same time.
Now, what is being said? I am lost in the phase jargon. And both active and PR dont move in unison, there is air spring the sound wave has to travel that air-spring, of course due to the wavelengths being so large they may appear concurrent due to very small delay, but this is valid for normal PR also. What is so different with SLAPS?

6) Claim: A traditional bass reflex port design, the system is limited in performance due to the air in the reflex port not being in phase or at the same speed of movement as the air in front of the active driver.
As far as I understand the PR does exactly what the cylindrical air mass of air does in a bass reflex port. What limited performance is being described, is it port velocity limit of port?

7) Claim: Active woofer unit should preferably have a resonance frequency (FS) of 30Hz or less and not more than 35 HZ.
In the entire document, TS parameters are never considered or even mentioned and now this limit imposed on Fs, why cant I take Fs of 40Hz and tune PR to 25Hz? Haven't people done that already?

8) Claim: Typically 16 mm MDF or thicker. Particleboard or plywood are also excellent materials.
For long stroke active driver and long stroke SLAPS PR, isn't 16mm too thin, should it instead be saying to use more thickness and more bracing than used typically?

9) Claim: It is important that you do not exceed the maximum specified enclosure volume. The air inside the cabinet acts like a spring and the larger the enclosure the lower the linear output. This also introduces distortion.
10 "inch 20 - 45 liters internal volume sealed cabinet
12" inch 30-60 liters internal volume sealed cabinet
15 "inch 35-100 liters internal volume sealed cabinet
18" inch 50-140 liters internal volume sealed cabinet

As far as I understand the opposite is true, and this is what I read, I dont remember where. Lets assume the volume of air displaced at Xmax of active driver is Vxmax in each direction, then as the cone goes in at Xmax the active driver reduces the volume of the enclosure by Vxmax and the stiffness of the enclosued volume increases, same way, as the cone goes out at Xmax the active driver increases the volume of the enclosure by Vxmax and the stiffness of the enclosued volume decreases. This increase and decrease if substantial, causes distortion. If the enclosure volume is large then the Vmax and the corresponding change in stiffness is negligible and distortion is negligible. Now, if if we reduce the enclosure volume then this Vmax becomes a sufficient portion of enclosure volume causing large changes in stiffness at both the ends at Xmax, thus distortion increases. The Vmax of the driver should not be more than 5% of the enclosure essentially putting a lower limit on tghe enclosed volume. Thus, a large active driver needs larger enclosure and higher Xmax also needs a larger enclosure. Of course, the actual frequency response still has to be simulated. Isn't it the same reason that when Sunfire put their large excursion drivers into very small enclosures they had to improve distortion using servo based electronics/amplifier? How does a small volume benefit SLAPS?

10)Claim: By placing SLAPS right next to the active woofer so you run the risk that at the acoustic resonance frequency there may be a negative interference which and the can lower the overall sound pressure level of the deepest bass tones. The lower the resonance is set, the less likely it is that there will be an issue. Best results are obtained by placing it on the back or side of the cabinet.

Firstly at box resonance the active driver moves the least, it hardly produces sound, the entire output at this frequency is from SLAPS so where is the claimed cancellation coming from. And if we move the SLAPS to rear even then both the drivers output is within 1/4 wavelength, so if cancellation has to somehow occur, it will occur the same way with a rear mounted SLAPS, no?

Thanks in advance,
Warm Regards,
WonderfulAudio

I've been working on a bass 8k (power supply seems identical to MD8000.1 so I've been browsing repair posts for those as well). I've replaced IC9, IC3, and IC1 and any accompanying SMDs that needed replaced. I replaced both power supply, output fets, and gate resistors. With the rectifiers pulled to isolate the power supply I can't get it to build a square wave on powerup. IC1 builds a perfect 40khz square wave, IC3 not so much, it tries to build a very odd signal initially and then goes flat once the amp goes through it's power up cycle. While testing R150 went up in smoke. I'm running out of ideas and looking for some guidance. I will be buying Perrys book as soon as I have the funds as well

Any help is greatly appreciated, I have a lot to learn and am very appreciative of any guidance and tips. Thank you!

I’m about to embark on building the Lampucera DAC, as described by Serbian YouTube star iiWi, You can see the video here:
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He claims this is the best DAC he has ever had in his listening room.

The DAC is a precursor to the Lampizator line developed by Lucasz Fikus. Details, documentation, from iiWi here:
https://drive.google.com/drive/folders/1MvSMdEsZ8DPtGMXrzUgQ7ceyAVS86uxO?usp=sharing

Ebay starting kit from HKaudio1 (Lawrence, who has been very responsive):
https://www.ebay.com/itm/1863217614...zPANM_6Rl2&var=&widget_ver=artemis&media=COPY

I’m probably not going to use Lawrence’s included tube output stage, instead following iiWi’s version with the 6N6P [but maybe experiment with the eBay one first].

My first two question areas, for which I am seeking advice:

1. What do you recommend as a source for metal chassis that is easy to mod, and large enough for transformers and giant capacitors as iiWi had?
2. If you look at the schematic, it is based on 220V transformer on input. I have US 120V input. What transformer changes are needed?

• A. Best to stick with toroidal transformers? Seems like a lot of audio guys prefer laminated. Can you recommend any source that is up to the standard here?
• B. I assume it’s easy to find a 120V to 6.3V transformer for tube heater. Any suggestions?
• C. It looks like the anode supplies start with 120V. Does that mean I don’t need any transformers for them?

If anybody has done this, and/or has advice to offer, I’d be most appreciative.

I'm a 2 year student of Ho Chi Minh university of Technology, Electrical & Electronic Faculty. I have passion on making amplifier so that is the reason why i choose that faculty.
It's nice to meet youuu.

I got this amp with the power supply and output sections both having blown fets. I replaced the fets and now when I power it up the power supply starts fine for the first 3 seconds Drawing .4 amps. But when the output stage kicks on the amp draws current for a tenth of a second and the output side shuts down. And keeps cycling this way

Dear all,
more for experimenting than of any practical value I would like to ask
this nice community for inputs & opinions on two related, highly theoretical projects,
the first one realistic, the second one utopia. I asked ChatGPT a bit for answers, but I'm not sure
how accurate the information gained is.

Project #1 (software):
Task: Retrieve digital audio samples of very high quality.
Split the audio range (20 Hz - 20000 Hz) of these samples into non-overlapping, logarithmically spaced bands of a variable number "n".
"n" variable for experimenting, f.ex. n = 1 up to 1000.
Measure total amplitude of every single band and apply this amplitude to a sinus wave of each
band's center frequency. Add all these new sinus waves together again to receive a summed signal which is a 'reduction'
of the source's audio signal (Fourier etc.).
Base Questions: How many bands "n" at a minimum are necessary to understand voice signals again from this source signal reduction
& resynthesis ? And how many at a minimum for 'rather' uncompromised audio quality ?
(Interestingly modern cochlear implants (of course no HiFi quality) use the very low number of 8 - 22 different frequency bands,
that are overlapping, however, and thus correspond possibly to 6 - 12 different bands only, effectively !)

Which software(s) then could do this job for sample source signals efficiently and accurately, but not necessarily in real time ?
(the problem is of course more complex, because not only amplitudes but also the phases of the signals also are important
across these manipulations).

Project #2 (practical utopia):
To build a loudspeaker with a large multitude of single low cost chassis.
Each chassis emits only one single fixed frequency, and each is triggered by an upstream
(cheap & as small as possible) amplifier that receives modulating input only from single sinus waves
(from Project #1).
Question: What is the minimum number "n" of chassis with logarithmically spaced fixed sinus signals
to recover 'rather' optimum audio quality (20, or 40, or 200, or 1000) ?

thank you kindly for any input & critique,
good night,
FrankieS

I've had them for ages and it's time to move on. $600 plus $20 shipping in US . Probably over $70 abroad. Only transformers are for sale.