I saw this today. Does anyone know anything about the merits of this reissue? Googling a bit it looks like a JJ Electronics venture?

Hello all, I’m belatedly posting an introduction despite having joined years ago. In the meantime I’ve come here often to read and learn - many thanks to members who have provided helpful information and guidance!

I became fascinated with audio in my teens and built my first speakers at that time with the help of my carpenter & joiner grandfather and his workshop. I know he was pleased to be able to share some of his skills and time with me.

Since then I’ve remained interested audio and in DIY repairs, especially of speakers, but any time it renews the usefulness of a quality product. Often this serves as an interesting challenge that also provides a learning opportunity. Add in some good music and what a great hobby this is!

I’m beginning to dabble a bit more in speaker design lately, now with the benefit of much more sophisticated tools, parts and access to info than when I was younger!

A friend has owned a Bose Wave with a DAB module for 20ish yaers. Recently when listening to dab radio on BBC stations 2,4 and 6 the sound switches on and off constantly. About 1 second intervals and consistent across these stations. Other stations work fine or have burbling from a weak signal. The radio has been in the same place for years with no nearby changes. I've moved it around her home with no improvement. No faults at local transmitters. Any thoughts? Is this a signal problem or an electrical, software or hardware fault?

More of an interest check as this is currently in use, would sell this DIY separate PSU and amp boards phono stage, set for MM carts but could be jumpered for MC (100ohm input).
Boards have some smd components differently from original Emerald boards.
Asking price 200 eur, details in pvt thanks

Good evening all,

I have begun to give some thought to experimenting with making turntable belts. My DIY turntable uses a heavy platter with massive bearing. So far I've tried rubber belts but want to try other material. I have been checking out the Teres turntable and not that they have used various materials to drive their heavy platters. My platter weighs about 15 pounds which is not light.

I was looking at starting with "leader tape" but note that is does not seem to be sticky enough. I would think that platter slippage would be a problem with this material. Any thoughts from those of you who have gone down this road? Thanks for all comments.

Bob🙂

Guys,
Does anyone know how to make a turntable belt?
I'm trying to figure out what materials I can use and how to actually make it (searches on the internet find nothing other than "replacing" belts).

To give you some info: I am using a Pro-ject Genie motor and an acrylic platter made for the genie (acrylteller).
However, the distance between motor and platter are currently quite a bit more than on the genie, so I cannot use the genie's belt.

This is a tpa3255 board that can be found everywhere on amazon. Is this a good one ?

Hi everyone,

I want to make my first set of speakers and after some research I'm at a point where I have a design. I would like some feedback from some more experienced people like yourselves before ordering all the parts and start building.

I've made the choice of making a two-way speaker inspired by the JBL L82's so the dimensions will be quite similar. For the drivers I think of pairing the Dayton Audio DA215-8 8" woofer with a DC28F-8 1/8" tweeter. The reasoning behind this, is they will create a similar look and I can use the frequency responses from the DA drivers in VirtuixCAD.




Now where I really can use some feedback is in the crossover design, shocking I know! This being my first ever crossover design, you can only do so much research before you arrive at a point where your basic knowledge gets you no further. For now I've come up with following design:



I'm looking for a warm sound, these speaker will be placed in the living room so it's not like I'm looking for a perfect reference sound. I'm trying to keep the crossover as simple as possible, no need to spend hundreds of euros for minor improvements at this point (that will be for a following project once I got some experience).

What I would like to know is if this looks like a solid start for a first project, but mostly if there are any mistakes I made or important stuff I missed.

Thanks!

Hi all!
Andrea and me and Pavel Pogodin have new design dac with input Ct7302,
Please see some . Thanks

STAR Pure DSD DAC

1 x Star Pure DSD DAC module
1 x Controller LCD module
1 x XLR and RCA output module
1 x Silver remote

This not include Amanero USB module (you can buy directly) and this not include 6.5V 20VA transformer.

INTRODUCTION

The high resolution PCM at 96-192KHz 24bit offer the possibility to have a good quality digital signal exceeding the big limits of the CD.
The DSD is very different from PCM, using a sampling frequency 64 times higher than that of a standard Compact Disc, offers a frequency response of up to 100 kHz and a dynamic range of up to 120 dB across the entire audible range.
The DSD on paper should be better than hi-resolution pcm like the 192KHz 24bit because the two conversions (from and to the analog) are more simple (see this article from Korg website) but the AES Convention Paper 6086 and AES Convention Paper 5395, seems to contradict this.
The DSD signal can be directly used to reconstruct the original analog signal with a simple RC filter but with this method we get many digital noise also using a good digital and analog filters so forget this method.
I have lost many time and money to test these solution, using different USB to DSD interfaces, I2S isolators and D-type flip-flop.
The little Lampizator and RT audiodesign companies has succeeded to reduce the noise and produce a DSD DAC with this method but with some limits.
This project here exposed has another approach, it is based on the DSC1 that is an Open Hardware, "discrete" delta-sigma D/A-converter developped by Signalyst, the DSC1 is able to convert the DSD signal to analog without noise and without a DAC chip.
The DSC converters does not work with a PCM signal so it is necesary convert the PCM to DSD on the fly during playing so it is necessary to use computers with adequate performance.
In this project we have used the CT7302PL single chip dual channel audio digital to digital bridge with a sample rate converter to convert PCM signals to DSD.


HARDWARE

The core of this design is the CT7302PL with the following specifications:

SPDIF support up to 768 KHz/32bits mode
I2S support up to 768 KHz/32bits mode
DSD support 1x/2x/4x/8xmode
DoP support 1x/2x/4x mode,throughI2S
DoP support 1x/2x/4xmode, through SPDIF
PCM SRC / ASRC fully support 32 KHz~ 768 KHz.
PCM / DSD / DoP to PCM / DSD / DoP converter with SRC / ASRC
Crystal reference clock / MCLK / DoP / Mute status output
Auto De-emphasis32KHz/44.1KHz/48KHz.
Auto detecting PCM / DoPformat.
Auto detecting I2S / DSD interface.
Volume control with fading in/out.(+18dB ~ -110dB step 1/32 dB)
SRC / ASRC 32 bits dynamicrange(192dB), THD+N (-174dB).



After the CT7302PL chip there is the DSC in the differential version designed by Pavel Pogodin with the output transformers to filter and to convert the output in un-balanced and balanced signal.
The 74AHCT595 are high-speed Si-gate CMOS devices used for the serial-to-parallel data conversion.
This module use a mute circuit to eliminate any click in the transition from one track to another using the TS5A3167 (SPDT) single-pole double-throw analogswitch .



This module need a AC power supply in the range 6.5V - 7V and it can power the Amanero USB module with a dedicated 3.3V.
On Amanero module to exclude the USB power supply and use an external 3.3V is necessary cut a wire or remove on-board regulator.
The USB interface used is the Amanero with the normal firmware to support Native DSD.




The Controller module included in the kit use the 16F877 chip, a 20MHz Enhanced 8K Flash Microcontrollers.
It drive a 4 x20 characters LCD and it is connected with the I2C bus to the CT7302PL.
A separeted power transformer is used to manage the standby function.


OUTPUT TRANSFORMERS

The output transformers are necessary to mix the differential signals coming from the 74AHCT595 in phase and out phase.
These are also used to give un-balanced and balanced output signal, the module integrate a relay to switch the ground connection.
The models has been selected by Pavel Pogodin after many test and also I have compared these with other models with much higher cost always preferring these.
These have a turn ratio of 2:1+1, made with a permalloy core with a thickness of 0.16mm and an inductance about 340H.
The declared frequency response is 10Hz - 195 KHz at -0.2dB for the yellow and 20Hz - 80 KHz at -0.2dB for the black type
Yellow type has more "air" and black are probably more balanced but it all depends very much on the record or even his mood.

Taobao
AliExpress
Alixpress type 2


REMOTE



SOFTWARE

This hardware is compatible with any PCM and DSD signal so to play music you can use any audio player.

Here follows some player in order of sound performances.
HQPlayer by Signalyst available for Windows, Mac OS and Linux, there is a Server and a Desktop version at a cost of 145,18 euro
Daphile Audiophile Music Server for x86 hardware, it is free but it need a dedicated hardware
JRiver Media Center available for Windows and Mac OS at a cost of $49.98
Foobar2000 freeware
In same case it is necessary increase the output level so use in the setting menu the V+ and -V buttons to set +6dB. +12dB or +18dB, I suggest a max of +6dB because otherwise the distortion can increase.
There is also a function to set an amplification of +6dB for DSD tracks because some player give a lower level for these.
All the settings can be saved in the EEPROM so these will be set at the next power on (press mute button on Setting menu).


MEASUREMENTS
Output at 0dB near to 1.5Vrms.


REVIEWS

STAR DSC took first place in the contest organized by the forum Vnav

Here is the result of a test in October 2019 with a friend of mine with a lot of experience in recording and playing audio.

Yesterday evening the first serious listening test about the new dsc module with CT7302 vs NAA (Network Audio Adapter) DSC module.

The quality of the last DSC with CT7302 is very high, the same details and the same sound stage of the NAA DSC module.

The NAA DSC module with the HQplayer filters is a little bit more softer but it is not easy define if it is more or less near to the real sound.

Using the CT7302 with jRiver the sound is very natural and analog.



PHOTOS

I'm returning to diy audio/electronics after a few decades and hope to learn a lot here.

Hello,
I am from NYC and am into tube audio and English speakers. Currently running Quicksilver V4 monoblocks with a Doge Audio 8 tube preamp into ProAc Response 2.5 speakers. Looking forward to learning and interacting with the group. Regards, Jed

Is there anybody building home audio speakers in an infinite baffle style? AFAIK, it’s so common, and popular in some places, in car audio.

1) using the driver in an extremely low Q, such as 0.5 or lower
2) using the driver with its natural roll-off on low-frequency response
3) extremely large closed enclosures

Do these three terms mean the same thing?

Also, what are the criteria for indicating that the drivers are suitable for the infinite baffle enclosure?

Hello all. Trying to get my head around super capacitors for a portable PSU that can charge up very quickly. Using the example in the linked video, how many of those modules would be equivalent in storage to replace a 48v 10AH Lithium-ion bank?

The 48v is for this amp module

Login to view embedded media

Hi Folks,

A few years back I inherited a Yamaha CDX-410. Until recently it's been in storage but from what I can remember it had a sticky drawer when I got it but in spite of this it still worked. I'd like to save it from e-waste and get it working again.

After opening it up, i can see that it definitely needs a new belt for the tray as it's quite slack and has lost its tension. However, I also noticed that when I put a CD in and tried to play it, it's not spinning. So I'm thinking that the belt for the laser probably needs replacing too? I just want to check that the lack of spin is possibly/probably being caused by the belt not moving the laser into position?

This is guesswork on my part as I don't have the service manual.

Any advice or suggestions related to this is welcome.

Cheers,

Chris

Hi.

I’m looking for help, guidance and possibly consultant work to design and develop an amplifier.

Basically I want to build an amplifier with 3 line in inputs and 2 microphone inputs.
Also for every input I need to be able to trigger to which speaker set to send the audio. (Group A, Group B or Group C)

I also want internal storage to store audio files that can be configured to play from various trigger signals.

I figured I will need an MCU for this like stm32. I have some more documentation I can show if necessary

Any pointers to get the ball rolling?
I am willing to pay for help with design and development for a prototype

Thanks.

New member today, as most here I'm sure really love music and to tinker, so why not look to combine both. Hoping to learn as much as i can, because as much as i love new equipment, i also love the idea of vintage and retro equipment as well.
Thanks for having me,
Regards, Steve

I see this has been discussed before, but I think in my case I have a better starting position. I have a mini pc that I would like to use as media player, but for that I need optical spdif out. Windows 10 recognizes spdif out and foobar plays all sample rates up to 192khz into it, so I just need a connector (I think). Pin 48 outputs spdif modulated signal during playback just fine. Any similar experiences?

Magnavox A531 Germanium Console Amp Reborn as a Vintage Stand-Alone Hi-Fi Component

Germanium transistor amplifiers are fascinating. They were proudly the first solid state designs, yet are an almost forgotten footnote lost between the chapters of vacuum tubes and silicon transistors. But germanium is worth exploring- in the same way that previously outmoded vacuum tube amplifiers are worth exploring, even though they too, had obvious design short-comings compared to the venerable silicon transistor. The germanium sound has been compared frequently with tube sound, and most of this sonic "coloration" comes from the same ingredient as tube amps- audio transformers in the signal path. Transformers provide for a fat warm bass, well defined, punchy but non-fatiguing midrange, and a delicate, silky high end. This treatment can be very beneficial when paired with modern digital sources, which are often described as harsh, technical, or sterile. I find the germanium sound to be very pleasant, and with the right music intoxicating. Those brave enough to explore germanium I think will end up giving it a welcome place among the pallet of flavors we chose from in our day to day listening.

This thread covers the restoration of a 1962 Magnavox germanium console/record player amplifier chassis to turn it into an attractive stand-alone, dare I say, "high fidelity" amplifier component. This, the first part, will cover cosmetic and chassis restoration, and the second part soon to come will cover the electrical restoration, transistor testing, and circuit details.

I have been tinkering lately with the 12V germanium amplifiers found in affordable 8-track car players from the late 60's and early 70's. They can be found almost anywhere, from garage sales to Ebay for under $30 including shipping. These really are hidden gems- because they include all of the impossible to find parts (the interstage transformers, thermistors, and matching sets of germanium pre and power transistors) already in one functional package ready for your study and redesign. Typically being of Japanese design, they are generally high quality amplifiers in a very small package. However, they are pretty low power- With only 12-14V to work with, a class AB can only generate about 4-5 Watts per channel even into 4 Ohm speakers. This is perfect for near-field listening on a desk top or bookshelf, but is not for general full-room listening. A fun detailed example of one of these that I reworked into a small stand-alone test amplifier is detailed in my "Germanium Bake King" project.

I needed something with a more power, in the 15 to 30 Watt per channel range to drive my larger vintage 3-way speakers for full room listening, and a console amplifier chassis seemed just the ticket. I had previously rebuilt a Magnavox 9300 series 6BQ5/EL84 push-pull tube amplifier chassis to be stand-alone, and thanks to the amazing Dave Gillespie redesign of this chassis posted on AudioKarma it became quite the audiophile contender and my favorite amplifier. Reworking a Magnavox germanium amp would be a perfect compliment in my collection.

When Magnavox first released their new solid state "Astro Sonic" line of consoles in the early 60's, they used germanium power transistor output stages, driven through interstage signal transformers. As these consoles age and are discarded, they provide a ready source for workable examples that can either be converted directly to stand-alone, or harvested for otherwise impossible to find parts to be reused. Many of the later models incorporated the power amplifiers into the radio chassis so they are bulky and not readily converted to stand-alone, but are a good source of parts. There are only a few designs that used a stand-alone amplifier chassis separate from the radio, primarily from the early 60's, such as the one I chose for this project.



I found this 1962 germanium amp chassis from a Magnavox record player for sale on ebay. The seller offered it for $25 plus $25 shipping, and I just could not resist. It looked pretty nasty, but would be a perfect fit if I could restore it. The seller said it did work, so I knew the bones were good, so it probably just needed a full re-cap and some minor upgrades. This is a Magnavox chassis model A531-01-00, which used the same chassis box as it's bigger brother, the A551-01-00. (In Magnavox chassis numbers, A is for Amp, A531 is the model, -01 is the version, and the -00 is revision) The more powerful A551 was used in larger full size Astro Sonic consoles with both radio and phono and was rated at 25 Watts per channel. It had a larger power transformer and used 47P1B transistors, and larger filter and output capacitors.

An example of the bigger A551:


My A531 chassis, with the smaller power transformer and the 38P1C transistors, was used in smaller stereo record player only consoles of unspecified output power. Given the supply voltage is -38V instead of the A551's -44V, I estimate about 18 Watts per channel or so. Still plenty big enough for what I need, and a good companion to the 15 Watt per channel 9300 series 6BQ5 tube amp. The interstage transformers were stamped 1386235, the 138 meaning Stancore manufactured, so excellent transformers, and the date code of work week 35 of 1962. The power transformer was also Stancore and had a similar date code work week 31. The transistors looked pretty roached- badly darkened and corroded, but they did work. The chassis still had the original molex type connector to the radio/phonograph, and the spade type connectors for speakers and pilot lamp.

To begin the cosmetic restoration, I first documented everything with photographs and notes, especially under the chassis. I disconnected and removed the power transformer discarding the really ugly looking screws and sheet metal nuts, then carefully removed and stored the transistors and heat sink to clean everything up. The only thermal paste present under the transistors was a thin oily residue, and dirt had made it's way under the transistors and the mica slips were in bad condition. This is an important area to attend to in older equipment with exposed transistors, which can benefit greatly from new mica slips and modern thermal paste.



What I feared was heavy corrosion on the nickel plated chassis turned out to be only a light fuzzy haze of corrosion, mixed with baked on dust. I tried cleaning first- alcohol, mineral spirits, and even acetone hardly made a dent. I found the fuzz was most easily removed by scraping- with the sharp edge of several wooden clothes pins that did not scratch the nickel. It was slow going, inch at a time, swapping out clothes pins as the edge dulled and started to grind into the nickel. That was followed by a vigorous rub-down with a terrycloth rag soaked in white vinegar to dissolve what I could, dried, then cleaned thoroughly with a water damp rag to remove the acid from the vinegar. While the nickel took on a nice reflective shine, it was still hazy-cloudy where corroded. At this point I could have started using metal polish like Brasso to grind down through the haze, but I don't like the shabby-schick look of over-polished nickel- it never looks right. I am reminded that with most of my projects, it's about what's under the hood and preserving it's original vintage character, not how fancy it's decorated that I really care about. It's vintage, and a bare knuckle nuts and bolts chassis, so let it be what it is in humble and dignified authenticity.

The remaining light surface rust spots on the nickel plate, rivets, and tops of the transformers came off pretty easily using a fine brass bristle brush from Harbor Freight. The brass did not scratch the steel or nickel, but removed the vinegar-softened rust down to a really nice looking patina with no damage. Be careful around the cloth covered wires and the paper/plastic wrapping on the audio transformer windings, as they damage easily even with the brush. I clipped the wires and disconnected the molex connectors, drilled out the rivets holding the the phenolic spade connector strips for the speaker and pilot connections.



I see a lot of different ways of dealing with extraneous holes in the chassis, some not very pretty. I find the most attractive treatment is to tack sheet metal patches from the inside. I keep a stash of vintage sheet metal pieces from the junk chassis I cannibalize, to cut patches for the holes. Vintage cadmium and nickel plated is excellent for soldering and is the easiest, but galvanized will work in a pinch. Fortunately I have an old monster 250W soldering gun from the thrift store that works wonders for soldering terminal strips and patches directly to the steel chassis, but a regular 140W Weller will work if you are patient. First clean the underside surface around the chassis hole with a scrap of sand paper or green scrubbie (don't use steel wool unless you like random shorts!), then add a few drops or dabs of soldering rosin. Once the plates are tacked in place, you can drill new holes for a power switch or input connectors, etc. I prefer to have the new device sit within the confines of the hole- Overlapping over the outside looks tacky to me.

The original standard Magnavox RCA input connectors are very close together, preventing you from using almost all RCA patch cables. I have found that the easiest and most attractive way to remedy this is to remove them, put in a patch plate, then drill for two new individual RCA connectors that are spread apart as far as possible while still fitting inside the original opening. This will allow enough space to use all but the fattest RCA cables.

I really liked how the appearance worked out on my 9300 tube amplifier, which kept very clean and understated, and put on an oak plinth with brushed nickel drawer pull handles, so I did the same thing here. The oak came from the center of a $3 used cabinet door from our local Habitat for Humanity which I cut down, sanded, and treated with the Natural shade of Watco Danish Oil. I really love that stuff! The drawer pulls were the most plain jane brushed nickel from Home Depot. I cut a sheet metal shield plate to sit between the chassis and plinth from some HVAC scrap also from habitat. The shield is held down flat on the oak with two small screws near the center to keep it from bowing up and touching something. For speaker outputs I chose the same type of small profile panel mount 4mm banana jacks as I did with the 9300. I really love the vintage understated look, and prefer ease of banana plugs for most of my speaker cables.



Stay tuned for part 2 coming soon: Electrical restoration, transistor testing, and circuit details

Hi- I want to build a pair of WESTERN ELECTRIC 124 or 142 theater amplifiers. Is there anyone out there who knows about Western Electric amplifiers? I have a number of questions>

What is the difference between the 124 and the 142? I haven't decided which one i want to build.

Is the transformer input a big part of the sound? The vintage ones are impossible and expensive to get. Are there some modern replacements for these input transformer parts that will sound good? I have never used an input transformer. How do they affect the sound?

The 124 schematic says there are two ways to hook it up : one where is generates 12 watts power and one where it generates 20 watts of power. I want to hook up for twenty.......Is this a class A and class AB power configuration.?

Please someone be my guide. I have made six amplifiers and I want to continue but I am still quite an amateur and a copycat. Now I want to copy W.E. gear. Everyone raves about these vintage amps.

Good evening @everyone! My name is Sean A. I'm a rookie EE with two years out of college experience. My frustrations of audio amplifier design brought me here as even in college, I could never get the perfect sound or power that I wanted. So I have thrown in the towel and am ready to meet and learn from some good folks who are way more experienced than me. Pleasure to meet everyone!


- Cheers from USA🙂👍

Which chinese TPA3255 amps do you recommend?

3E doesn't ship its amps to me.
TI EVM is quite expensive.

Thus, I'm looking into chinese TPA3255 amps.

What about

* A generic no-name chinese TPA3255 amp like this
(This one seems to use TI LM317 voltage regulator with maximum input voltage of 37V. Other chinese TPA3255 products use LM2575T-12 with maximum input voltage of 40V)
* A 32V 5A adaptor like this or Mean Well LRS-350-36
(Would it be safe to use a 36V power supply with chinese TPA3255 amps?)

I haven't yet seen a chinese TPA3255 amp that can comfortably work with 48V power.

If chinese TAP3255 amps sounded properly and lasted long, I would consider buying one.

Hi everyone,

I’m working on restoring my father in law’s TL12s and would love some input and advice. I have two amps and a spare third chassis with missing ironware and a mix of new and old components. There is also a Point One preamp and Troughline tuner but I am not looking at those.

The amps were last tested 20 years ago but were almost certainly in storage before that.

I have a multimeter and new digital LCR meter, and old (untested) CRT oscilloscope but no other proper test equipment.

What I’ve done so far:

• read the very helpful advice at 44bx.com
• remove the ironware and test for DC continuity with multimeter. One of the chokes has gone open circuit but luckily there is a spare in the box of stuff I was given.
• clean up the amp chassis
• test the capacitors and resistors in circuit using an LCR meter.

Questions and next steps:

1. The 4uF+8uF+4uF capacitors in the can show no signs of leakage. The LCR meter shows nominal values (3600nF-4100nF, 7800-7820nF and Vloss 0.1% ESR 0.5 Ohms for each). What else do I need to do to test if these are ok to use? Or should I just bypass them with modern caps?

2. I am planning to replace the 5 coupling capacitors in each amp with 0.27uF 630V polypropylene from Cornell Dubelier. I can’t find a reliable source of high voltage 0.25uF capacitors anywhere. Is this a sensible choice?

3. I will replace all the electrolytics with identical values, and any resistors that are out of tolerance according to the list on 44bx.com

4. How can I further test the ironware? I am getting very low resistances (MM shows about 0.5 Ohm) on the mains transformer low voltage secondaries which makes sense to me. I am also getting very low resistances on the outputs secondaries (about 0.5 Ohm).

5. The output transformers are wired for 8 Ohms impedance, but the associated resistor/capacitors are the 32 Ohms options. Maybe the transformers were rewired at some point? Is this a problem?

6. One amp has no R23 in the circuit going to the cap of the preamp valve. It just has a wire going direct to the valve cap. Should I change that? The other amp has a potentiometer in the input circuit and I haven’t worked out what is going on there yet.

5. What advice is there on powering up safely once the steps above (and any others) have been addressed?

6. What else have I missed

I happened to be wandering through YouCrack not long ago, and stumbled upon a video a guy posted saying that he had found a RadioShack store that was actually open (in Indiana). I assumed it was a novelty, someone with an old sign, or clearing old inventory or something and did not take it seriously. Then, the other day, I was driving through Hamilton, Montana (Where they filmed "Yellowstone") and there was a RadioShack store with an open sign. I almost left skid marks dodging into the parking lot and jogged in, my mind filled with the memories of discrete components and perf board I bought there so regularly.

There it was, with almost all of the inventory I remember it having around the time the stores in my area closed. The very nice fellow there indicated that RadioShack never actually went totally out of business, and that there were 500 "Mom and Pop" stores still open. He said the new owners of RadioShack was soon going to be opening new stores across the US, and greatly adding inventory to them each month.

From the website:

"Unicomer Group, through its affiliate Global Franchising Corporation (GFC), acquired RadioShack's intellectual property assets and domains in about 70 countries around the world, including the United States and Canada, Europe, and China.

RadioShack is coming back in the US with an extensive product selection that ensures our customers they will find exactly what they need to carry on with day-to-day lives or transform their home and office. Our electronics range including: music and audio equipment, gaming equipment, business traveling products, dependable computer accessories and more."

My name is Alan and I am a n00b tinkerer. Tubesplain to me, please .... I insist! I currently live in Alabama. I have been using Meitner solid state gear. I recently restored a pair of Fisher XP-16 speakers. Now I am getting acquainted with a Dynaco ST-70 that has passed through a few hand before mine.

Sunvalley SV-Pre1616D 115/230 version (point to point pre-amp project)
Made in Japan (Nagoya)

SunValley SV-Pre1616D Tube Line Stage Kit Review | Wall of Sound | Audio and Music Reviews
AVAILABLE now $975.00
Assembled by Sunvalley with 2X VCAP ODAM 4.7uf x 2 $1,525.00

EQ1616D Phono Amp









- 12 AX 7 JJ ECC 82/12 AU 7　
- 12 AX 7 GD 12 AU 7
- Mullard CV 4003/12 AU 7 (3 matched) SOVTEK 5 AR 4


You can use the following combination

① 12 AX 7 - 12 AX 7 - 12 AX 7 (Sharp and high contrast)
* Standard combination (SV - 722 Marantz type and same circuit)

② 12 AX 7 - 12 AX 7 - 12 AU 7 (Skeletal feeling and entity feeling of medium low range)
* SV - 722 Mckin type sound image Reproduced

③ 12 AU 7 - 12 AU 7 - 12 AU 7 (round and resonate rich)
※ Featuring a rich overtone feeling of the SV - 310 series


Input: 4 lines [Input 4 can be changed to USB input (option)]
Input Volume: Yes

frequency response: 15 Hz ~ 70 kHz (-3 dB)
gain: 15 dB

size: 250W, 225D, 135H (mm ) ※ including protrusions
weight: 3.6 kg






































































[

Hey all!

I have a wood working shop in my house and I'd like to make me a pair of bookshelf loudspeakers for my office based on automotive simple 2-way kit (midrange + tweeter) - nothing very fancy, just a minimum decent quality (preferably with port for bass enhancements) for enjoying music when working on computer. Sometimes I get sick of listening my playlist on phones.

Could a good soul please give me the directions to a free plan of bookshelf loudspeakers (with measurements)? I have browsed online but didn't get any luck.

Thanks!

🙂

Edit Feb 19, 2024: The BTSB was tested and verified to produce 49Vpp with balanced 4.9Vpp input and balanced output. This means it can easily drive 0dB amps like F4 to clipping levels. The LME49724 datasheet says that it should be able to drive 600ohm loads to 52Vpp with low distortion levels.

Edit Nov 23, 2020: Tips on videos on how to do your own SMT/SMD soldering:
BTSB Buffer - SE/Bal to SE/Bal Buffer GB

Edit Oct 22, 2020: new boards v1.3 for TH and v1.2 for SMT have corrected them layout error and verified to be working properly in all aspects.

Edit Sept. 4, 2020: Stop Press! Please note that there is an error on J36 (the phase is flipped). I am ordering new boards and will send out replacements to folks who have already purchased these. This only afftects one of the SE outputs. If you have no need for the SE output, it doesn't matter. There is a workaround to it here. So sorry about this but it was the one thing I did not check on the verification build.

Edit Aug 18, 2020: Mouser shopping carts for the BOM here. Thanks to Vunce for making these for us!

This is the Best Thing since Sliced Bread (BTSB) Buffer that I will be offering as a GB. It was designed by Jhofland to address a need that I had with my TPA3255 Class D amp which required balanced input with gain. Jhofland designed a prototype that had just balanced output with gain (selectable via jumpers) with either balanced or SE inputs. I tested it out and it works great.

Here was the v1.0 verification prototype that I built:


Member Redjr has already used the prototype version on his very nice TPA3255 amp build here.



I thought that a more universal buffer would provide a choice of either SE/Balanced input and be able to driver SE/Balanced outputs simultaneously. This might be useful for driving a subwoofer amp, for example. The topology uses a state of the art OPA1656 for the input buffers and state of the art LME49724 balanced line drivers and another OPA1656 for the SE outputs. Another OPA1656 provides a bootstrap for the input amp to allow lower distortion drive at higher drive levels close to rail voltages. The power supply is provided with a very low noise Murata isolated DC/DC converter to take 12vdc from a wall-wart to +/-15v using the DC/DC followed with a CLC filter. The BTSB is absolutely silent and adds no noise or coloration. It is very transparent and can be used as a simple signal booster in cases where you need just a little bit of extra bump in the output from your source or existing preamp.

With the ability to accept SE or balanced and to drive SE or balanced, and with your choice of 0dB, 6dB, 14dB, or 20dB gain selectable with a convenient 8-position DIP switch - you will find it an indispensible part of your electronics toolbox kit. I think that you will agree that is may be the best thing since sliced bread...

To see the schematic, please click below. It is too wide of an image to display inline.

Here is the layout:


Here is a photo of the PCB with a Neutrik XLR jack (plain Molex KK terminals are also provided if XLR is not needed):


Here is a measurement of a 1kHz low distortion signal from Victor’s oscillator and 20dB gain from SE to Bal mode and fed to XLR input of my Focusrite - the so-called loop back test with BTSB in the loop. It has noise and distortion below the measurable limit of the Focusrite.


Here is a measurement of the distortion of my TPA3255 w PFFB as driven by the BTSB in SE to Balance out with 20dB gain applied - the THD is lower than the TI factory data at the same condition. The noise baseline is very low at -130dB:


I'll post a photo of the populated board as soon as I get back from vacation.

We can get the GB interest list started. Boards will be 1.6mm thick, 1oz copper, ENIG finish, and green color solder mask. Construction is straight forward as it is mostly through hole except for the opamps. Price is $23 ea for the bare PCB. The BOM cost is about $65. Please see BOM below - I will post a Mouser shopping cart to make ordering easy (soon).

I have received questions about whether or not a version will be provided with the SMT parts pre-installed. Yes, I can do that and the cost for a BTSB with 4x OPA1656 and 2x LM47924 pre-installed will be $69 ea. The 6 opamps cost $21, and I am charging $25 for the SMT soldering service.

Also available in all SMT - 70mm x 70mm. No XLR jack. Same price as TH version (Schematic and BOM here).


Please add your name, desired boards, SMT pre-pop'd Y/N, and country below.


BTSB Buffer GB Interest List:
-----------------------------
Name No. of boards SMT pre-populated (Y/N) Country

Please place a pre-order in my shop if you add your name to the list above.
BTSB Buffer SE/Bal to SE/Bal Buffer | Etsy

There is a new panel mount version of the BTSB that has separate auto-switched RCA inputs. Anytime something is plugged into XLR/TRS, a relay automatically disconnects RCA's. This version also uses OPA1637 for balanced output driver (uses less quiescent current). Mounts directly to rear panel and no mounting standoffs needed. Very compact and conserves chassis real estate on bottom panel. Also reduces flying leads that can pick up noise.



Fit check with 3D print:




Here is panel hole template. Note that the vertical CTC distance below is for the Elecaudio RCA jacks. If you purchase the RCA jacks from my shop or the RTR BTSB Panel Mount then the distance is 7.25mm:


Board dimensions:

BTSB TH v1.3 board dimensions are 100mm wide x 88m high.

BTSB SMT v1.2 board dimensions are 70mm wide x 70mm high.

BTSB Panel Mount SMT v1.2p is 132mm wide x 45mm high.

Recently taken an interest a working on my first amp a Sony TA 2650. Low power from left side and checked around. I have 140mV on white white and 600 on red wire.

Folks,

I have been struggling with this project since last April. And I received good advice and suggestions back then.
But it got to the point where I felt that I no longer believed that the LM386 was the right IC for this project. (It was pointed out to me that it was ancient.)
So I've redesigned things a bit and will be using two MC33171N ICs.

The schematic was redone but was largely unchanged. That is, I substituted the new ICs and added, changed or removed connections accordingly.
So, for example, there's no longer the bias cap from the LM386 pin 7. And there's no longer a pin 1/8 gain adjustment.
But as the overall design is from an LM386-based schematic that I found on the net (and failed to store the link) certain components are still in place.
For example, the product info on the MC33171N shows me a freq. vs. impedance graph which suggests to me that the IC's output, unlike the LM386, is not 8 ohms.
Can anyone tell me what the likely impedance would be based on my circuit?
Also, there are a few holdovers as I mentioned. What purposes are served by the 220μF and 470nF caps on the output stage? For that matter I never understood the purpose of the two 470nF caps leading into the "Summing" 2-gang balance pot.
So I welcome your answers and suggestions.

Thank you,
Roy

So "Hello" to all the lovely people who make up this forum.

Thanks for sharing.

I have loved listening to music for as long as I can remember and I'm fifty eight now.

Since I was sixteen I have played bass and guitar so I have a special interest in electronics for performing.

Best Wishes......

🙂

Hello,

I am looking for references from a known manufacturer of small PCB transformers with a 1:3 turn ratio to support AC operation below 20V up to 3 to 5A.

A transformer that would look like those I saw at a Chinese seller but whose datasheet is unreadable.

https://www.aliexpress.com/item/1005001873197381.html

If anyone knows, thanks in advance.

Regards,

Stef.

Hi, Tom here in wintery Columbus, Ohio. In our twenties my friends and I would prowl the high end stereo stores to hear stuff we could not afford. Then around 1980 my poor roommate decided he needed better speakers than his JBLs. I was reading a bunch at the time and Jordan had caught my attention (faster than electrostatics!). The roommate was convinced and I helped him make crude boxes. The modules were in "hatboxes" made of two Sonotubes filled with spray foam with particleboard on the top and bottom. Holy Moly the final system sounded fantastic compared to any top end system. The detail. It was a bargain compared to any commercial system. We moved on. I wasted too much money chasing sound until the Maggie's ended up in the basement now powered by a 70s 35watt Kenwood.
Jordan stressed as most important moving mass. The modules were .3 grams as I remember. Not bad for a 2 inch cone with a frequency range of 75 to 24k hz. He also stressed how bad crossovers are.
Now the Jordan drivers have much heavier moving mass but don't need to be crossed at 150hz like the modules.
I have now focused my desire to build some Markaudio speakers as the moving mass of a tweeter in a full range seems to be a relic of the past.

I'm a frail 75yo so be kind,
Tom 😎

Over the years I read here and there about a old speaker type called a boffle.

It consists of a open backed box with many felt curtains with different sized holes behind the driver. Here are some images to illustrate what it looks like




The idea is to "eat away the back wave" to emulate a infinite baffle.

My question is this, wouldn't it be better to use CLD material (constrained layer damping) in stead of felt curtains......or CLD material covered in felt?

In my mind CLD dividers would suck more energy out of the back wave, especially at low frequencies. I could make sheets from bitumen sandwiched between thin metal plates covered with thin automotive felt....

Is it worth a try?

http://p10hifi.net/tlinespeakers/forum/boffle-RadioElectronics.pdf

okay guys,
i did tda on a veroboard today. there is less than 20mv DC in the output. i used the circuit picked up from Rod's site, with minor modifications

1)added 2uf mkp input capacitor as he doest have one, which is necessary.😀
On the basis of following page, made other few changes
Avoiding TDA7293 pitfalls
2)changed the bootstrap capacitor (as suggested in pitfalls of tda) to 100uf
3)changed the NFB cap to 100uf.

NOTE-the decoupling caps are smaller in comparison to datasheet on the rod eliotts site, and i have used ceramic 100nf ones alongwith them.

The problem is, i did a side by side comparison to tda2050 on 18v rails. but! i am really disappointed by the bass tda7293 puts out on my speakers.
can someone lend me an insight?

Sanyo/B&O Icepower 200AC Rev.D, schematic about rev. engin., not complete finished

some time ago I had make trobleshooting and repair by a ICEPOWER module from B&O. Therefore I must create a schematic, that was not available by the manufacturer. But the schematic was difficult to reconstuct, because the PCB use multilayer technology. So any connections are not to see and some other are unknown, where do they go (at whole four or five wires - I think).

Nevertheless this schematic could be of interest for one or the other.

Perhaps one of the members this can complete.

My second Allen & Heath XONE 92 has a bad channel strip.
This must be a design flaw as it happened to 2 units built 10 years apart.
Does anyone have a fix for this problem?
Thank You

Interested in your opinions, I'm looking for something cheapish with a sweet treble and reasonable power handling..

In general, high efficiency fabric dome tweeter without horn are hard to find.
But today I have read in the German magazine "Hobby Hifi" about a new device from the Italian brand "Ciare", type: "MT 320" (MT320)
http://www.lautsprechershop.de/pdf/ciare/ciare_mt320.pdf
(Italian language)

Are there any audible experience ?

An older phenol dome tweeter in this kind is that one from "Bass Art Box MkII" from the German brand "Glockenklang" (go to the last images from attachment) and "Acoustic Art MK-III" - go to
https://www.glockenklang.de/de/produkte/bass_systeme/acoustik_art_mk3.htm
Unfortunately, this tweeter was just a spare part and not as an industry standard available, and therefore there are some diy projects to create such a high efficiency tweeter, e. g.
http://www.6moons.com/audioreviews/bastanis/vc.JPG from
Bastanis DIY Forum

This Glockenklang dome tweeter is based to the no longer available RCF driver magnet TW116 ("TW 116")
and the cone from the appropriate recone kit
https://www.worthpoint.com/worthopedia/original-rcf-m39-rcf-tw-116-tweeter-1834169072

If there are a appropriate successor for the RCF TW-116 magnet, I can order this and the TW-116 recone kit for clone the Glockenklang tweeter, that have 99 db spl/2,83V/m efficiency.

Who knows more about such a RCF TW-116 successor ?

Murton-Pike Systems Vendor Thread

Single thread combined from others in Vendor's Bazaar.

PCBCAD51 available at Murton-Pike Systems

Touch screen compatible.

2018 Windows full version of PCBCAD51 PCB DESIGN SOFTWARE with 127 LAYER AUTOROUTER.

Runs on Windows XP (SP3) , Windows Vista and Windows 7, Windows 8 and Windows 10.

This is a mature product with no bug list, if I find a bug it is fixed immediately.

Support for this product is second to none, you are supported by the guy who wrote this software.

Schematic and PCB symbol designer wizards.
Auto creates SIL, DIL, circular and QUAD PCB footprints from your parameters.

Schematic entry with auto convert schematic to PCB ratsnest, unconnected pin scanner and single ended net scanner.

PCB entry with 127 layer rip up and retry auto-router with clearance and continuity check.

360 degree rotations of pcb components with obround pads.

Integrity checker, compares schematic and PCB for differences.

Component locater.

Parts list output.

Schematic/PCB component auto-renumbering and re-annotation.

RS274X Gerber file generator and NC/Excellon drill file generator.

Pick and place file generator with fiducial option.

3D PCB viewer module.

Output schematic to printer auto-sized.

Output PCB to printer in 4:1, 2:1 and 1:1 scaling, inversion and mirroring about x and y axis.

Merge schematics and merge PCB's.

Library scanners for fast component selection.

Gerber file viewer (PCBCAD51 files only)

Component locater, block-mode for repeats, shifts, rotations etc.

Net optimizer for shortest routes.

Auto component placers for minimum routing.

Recursive auto-autoplace, rotational autoplace and swap autoplacer.

Auto-place and route recursively function for lazy PCB design.

Unconnected pin scanner.

Forward annotation function from schematic to PCB.

Screen capture to bitmap file in schematic and PCB entry.

PCB's up to 50 by 50 inches.

127 copper layers.
127 resist layers.
Copper pours, each layer can be connected to a different NET.

2 silk layers (upper/lower)

Comes with symbol libraries, 4000, 7400, smd4000, smd7400 and general as standard.

User manual in each module

This is the full version and not a crippled, time limited or downsized version.

This is a fully integrated package and not a suite of amateur free programs cobbled together.

Fully supported package with email and phone help lines.

Note: This is the 2018 version and not an obsolete version.

I am designing a RCRC filter to go before a Jan Didden Treg for an aikido preamp.

Putting aside such things as cost, space etc.

Am I correct that the aim of such a filter is to get the fc as far below the mains fundamental frequency (50Hz in NZ) within an acceptable voltage drop and/or dissipation across the two resistors?

Is say 20Hz a reasonable target or should I be aiming lower if possible?

I got four TEBM65C20F-8 drivers. This driver has good review at PE forum. I want to try it for a compact bookshelf design.

I started from impedance measurement for extracting parameters. Instead of solely using line-level for small-signal parameter extraction, I used multi-level 0.1 to 5.0 V driving signal to get a set of VI curves. These curves were imported to LEAP to generate LTP models.

One analog output my AP S1 was connected to an amplifier. Output of the amplifier was connected to the driver under test via an 1 R, 1% current sense resistor. Voltage across the driver terminals and current shunt were connected to the two balanced inputs of AP S1, respectively.

Driving levels were 0.1V, 0.2V, 0.5V, 1.0V, 2.0V, 2.83V and 5.0V. Sine sweep with 513 steps was used. Added mass (2g) was used for Mms estimation.

LTD table of the four drivers are shown below. Their resonant frequency are "much" lower than that in the spec. The lowest one is 48.2 Hz. Qts is also much lower than that in the spec. Is it due to different tools for parameter extraction/model fitting or production variation?

Impedance curves of a sample are shown in the figure.

Hello,
just a little background. I have a wide interest in engineering, both electrical and mechanical and have worked in both disciplines.
I installed the Solar PV system myself and the solar hot water system.
I drive an MGF which I have maintained for around 10 years.
I love BBC Radio 4

I have a pair of 15" HPD/385/8 Tannoy Speakers.
Having recently cleaned the selector switches of one of the units I am considering replacing them with new ones.
However I guess that is a matter for another post.

Hi all -

I’m Batiste, 36yrs old, living in Paris. I’ve done some diy in the audio territory (thanks notably to Tubelab and reading this forum on a regular basis). I’d love continuing this great DIY journey here!

Batiste

Hi,
I wonder what are the real world effect of different values of Rf1 and Ri for non-inverting design. Going through data sheet and old threads points out that keeping it low to provide enough feedback current, thus less noise. Make it too low will increase too much current and heats up the resistor (leads to more noise). Also, Rf1 and Ri value are used to calculate Rb for input bias current. Too much current will also increase the noise, if I understand this correctly. Most people seems to use 20k/1k, which seems to be "magic numbers" from datasheet.

Nevertheless, I haven't found data "how much" less or more noise for different values of these resistors. Some manufacturers (op-amp) provide data of how much noise different, but I can't find for LM3886. Occasionally, I come across some design with higher value says 47k/2.7k or somewhere in between. At the end of data sheet (p22-23), TI/National also show case how to design a 40W @4 ohms amp, which, by example's requirement, they used 100k/8.2k.
https://www.ti.com/lit/ds/symlink/lm3886.pdf?ts=1736072004540

Please share your thoughts on this.
AP

Hi I have an amp ( NAD2700 thx ) whose output transistors were replaced at some point with Sankyen - I’m trying to find some genuine 2SC3281/2SA1302 to replace them with - not sure if there will be any benefit - only way I can tell is that my unmodified 30 year old 2400 sounds better than the repaired unit - and I’m not sure if going back to the Toshiba pair will make the difference but worth a try ? If so, how do I get genuine pairs vs counterfeit- the fake 2SC3281/2SA1302 may be worse than the sankyens I currently have

2 x 1 meter in like new condition. Price 200 euro including shipping inside EU. Payment paypal. I dont need this so offer are also welcome.

For sale here is a nice pair of the Sony Tamura output transformers. There’s a rumor they have nickel cores, can’t confirm, but I can confirm that they sound fantastic.

These are 5K to 8ohm with 600 ohm secondaries as well. They were gapped for 60 ma. , and sound great with EL84, 6V6GT, etc..

120€ paypal friends and family

Hello

I'd like to share a relatively new tapped horn design with you all. It's called Lonely TH15 Pro and developed
by Viktor Stoll from Germany. I stumbled upon Viktors TH designs in a German DIY audio Facebook group, he
has done quite a few tapped horn designs ranging from 6 - 18".

I had a Paraflex Type O 2x15 subwoofer for my garage setup wich was quite impressive, but very big and hard to place.
I didn't fancy building another one just to tackle the problems I had with room modes. I found the Lonely TH15 wich was
about half the size of my Paraflex, and figured that two smaller subwoofers willbe better than one big.
Having built a BFM Table Tuba a long time ago and liking the sound of it, I didn't hesitate to build a tapped horn again.

The Lonely TH15 was designed around Thomanns inexpensive The Box 15LB075-UW4, I asked Viktor if I could use The Box 15LB100-8W instead?
He promptly answered that the box can be built narrower with a stronger driver. Didn't take him many days to come back with a new design suited
for stronger PA drivers and even adjusting the plans for 18mm BB-ply that I had on hand, what a champ! 🙂

These are easy to build, not too big and I really like the way it sounds. The cabinet tunig is 42Hz, but to me it reallysound deeper.
For the kind of music I listen to ranging from blues, rock to metal (even some EDM now and then) I can't say that I'm missing anything
in the low end. What I really like about them is how musical it is, no one note bass and really nice sounding upper bass. What's also
to like is how efficient it is and the way it's present from low volume.

I have compare it to the Marty Cube loaded with a Lavoce WAF 154.00 wich is tuned quite a bit lower with an F3 of 27Hz if I remeber correctly.
The Marty is impressive at high volumes and sure it goes lower. But the Lonely TH sound so effortless and musical that for me it's a
no brainer which one to keep. The Paraflex is of course even more efficient than the TH, having two drivers and being double the size,
but the TH still is more HiFi and sound better higher up in the register to me.

Now I only need to build another one! Hope this inspire some one who want to build a great subwoofer.

Here are links to Viktors posts with simulations, measurements and building plans on the German HiFi forum.

Lonely TH15 Pro, simulations and construction plans in english available at the end of the post.
http://www.hifi-forum.de/viewthread-159-11222.html

And here is the regular Lonely TH15, where you can find the simulation and also the real world measurements.
http://www.hifi-forum.de/viewthread-159-11218.html


Easy to build, single row bracing.




From the left Marty Cube, Lonely TH15 Pro, Paraflex Type O 2x15

Hi everyone!
I just got a pair of Chinese 300b Monoblocks from eBay and have some questions and comments, and wonder if anyone who knows what they are doing has looked at them.
The amps that I got are sold by a bunch of different people but they all look the same. There is very little actual identifying labeling, the vendor that I chose has a funKenya banner on the pictures.
I got the version that came with PSVane 300bs and Russian rectifier and driver tubes. It only took two weeks to get to Pennsylvania from Hong Kong! It was very well packaged and the packaging and contents were undamaged.
There was no manual of any sort included, but I don't read Chinese so that isn't a great loss. The case has no identifying markings at all but there is a sticker on the bottom.
The first thing that I did was peal off the warranty stickers over two of the screws holding the side panels so that I could verify which socket is for the driver and which one gets the rectifier. The case is labeled 110 volts in several places so I checked the heater voltage for the 300b and it was almost 6 volts. I built power cords with 10 volt bucking transformers and reduced my line voltage from 123v to 110v and the heater voltage to 5 volts.
I tested them out on the workbench with small speakers and they appeared to be operating properly, so I brought them upstairs and hooked them up to the big system.
Right off the bat they sounded pretty darn good. Not really competitive with my big VTL monoblocks, but they had something to offer over the Skunkie Designs modified A12 that I had hooked up yesterday. After a couple of hours, they really started to sound pretty darn good!
I brought them downstairs and put them back on the bench with the small speakers out of phase and pushed up against each other, and the Sheffield Labs burn-in track running on repeat. I'm going to hook them back up shortly, after 4 hours or so.
My questions:
Has anyone who knows what they are doing looked at these things? They seem more "engineered" than the A12 but I still wonder if the circuit is actually properly designed and implemented.
I would love to get rid of the Russian tubes and use more common types. It comes with a 5U4M rectifier and obviously a 5AR4 would give me more choice and availability, similarly with the 6H8C driver tube, a 6SN7 is a lot easier to come by. I'm pretty sure that I can't just use the "equivalent" tube types, lol.
There is a multi-turn potentiometer on the back but no exposed test point that I can find. Does it seem possible that this amp is configured with adjustable bias? That raises several other questions.
I'm about ready to bite the bullet and order some better 300b's for it but if I can do something about the others while I'm at it that would be great.

Thanks,
Pete

Hi everyone,
I am now stuck and need your help. I bought, for about six months ago, a CD player of the type: Pioneer PD-S703. I wanted to do a DAC conversion according to Lukasz Fiku's instructions. I wound up a transformer and built the entire conversion inside the player. The problem was that I got a hum as soon as I connected it to my amplifier AUX input. Furthermore, I decided to try isolate the CD player, transformer, power unit and the terminal from each other in the hope that the hum would go away, but no it's still there and won't go away.
any ideas what could be the error?
Sends here some pictures of the construction and one oscilloscope picture with the measured B+ signal (Ch3) and the output signal (Ch2). It appears that the ripple in B+ affects the output signal DC voltage. What do you think? If so, how can I filter out all the ripple? Right now I'm testing with only one channel. 6,3 volt filament voltage appears to be flat (no ripple). Will be very happy if someone can help me with this!
thank you!

Hi, I have a JVC Nivico 5020u amplifier which i got from my dad, the only problem with it is that the transistors are blown. The blown transistors are four NEC 2SD180 and it says MA9X under it (I've also added a photo of it). I would appreciate if someone could help me find a replacement part.

Top end appears to be hot by 10+ dB, but it certainly reaches up there. Solen will sell them for $90 CAD, but they're currently on back order. Also, the spec sheet lists the same exact parameters as that of the 12-200LT. It appears as though they simply copied the text. I also noticed that the Xmax was mysteriously changed from 2mm to 5.25 on the 12-200LT, so I'd take that with a grain of salt. Aside from these things, it does appear to be an interesting driver. In particular, I can imagine the Karlson guys finding interest in this one..

Fane International Ltd Loud Speakers
http://www.fane-acoustics.com/downloads/Fane Sovereign 12250TC DS030513.pdf

Hey, everybody. I'm looking for a good electret microphone. I have some EM273s, but their disadvantage is that they are omnidirectional. I'm looking for a directional mic. Can anyone tell me what brand of microphone to choose? Maybe you know manufacturers in Europe? Thanks

I have n.16 Siemens D3A nos. price is 30€ each.

I'm thinking about trying a pair of the Sunbuck 2A3 monoblock amps that I have found on AliExpress and I wonder if anyone has any experience with them. Right now I'm using BRZ HiFi 300b monoblocks on the squawkers of my LaScalas and ACA monoblocks for the tweeters. The new amps would be for the tweeters, obviously.

I'm very impressed with my 300b amps and even more so now that they are just tasked with the mid-range. I replaced the WIMA coupling caps with nice Audio Note copper foils and took them to a whole 'nother level. Buying this sort of cheap equipment from China is something of a risk but I've had good luck so far.

Pete

I wanted to start a thread containing any bargain priced woofers, midbass and mid cone drivers.

That said, what is your favorite bargain cone driver and why you like it. Any measurements and data are also very welcomed.

I'll start with the Silver Flute W20RC38 in 4 and 8 ohms.

This woofer/midbass is highly underrated, especially for 1.25 cu ft tuned to 35hz. The midrange is also outstanding, with a very manageable upper peak around 4k. It handles tons of power and doesn't show any signs of strain, even at higher excursion in a 2 or 2.5 way crossed around 3k. Its a fantastic budget cast frame driver costing around 50 bucks.

Im not sure if I can get help here or not for this one. The factory radios in these cars have 3 external amps and a control box. That and, its especially important that this particular car Im working on stays with the factory radio.

AM/FM radio works so I know the unit works. I don't have a tape to test the tape deck.

The CD player had some issues that I worked through like a stuck load motor, dirty potentiometers, wiped the laser eye with 91% alcohol, etc..

Now I can get it to pull in audio CDs, and it will spins a bit at different speeds but it doesn't play. Eventually it ejects the disc. I tried multiple discs - CDR, real CDs, clean, scratched ones; nothing but spin and spit out.

Here is a good link with a BUNCH of photos on Page 1 AND Page 2. I already did what the link said but about the player skipping, but Im not even getting to that point at all as I have no audio. Its like the laser is just not operating.
http://www.turbomr2.com/MR2/HowTo/CDFix/FixCD-01.htm

Any help?

Does anyone know of any graphs which show the measured high-frequency horizontal polar-response of standard, off-the-shelf type, cone drivers when mounted vertically and inverted, so as to radiate omnidirectional from the back-side of its cone? Meaning, like in an Ohm Walsh style driver configuration, except utilizing a normal cone driver instead of a Walsh driver as the radiating element. This has been done before in many diy omni designs, and also, seemingly, in commercial speakers as well. Including, I believe, in Ohm’s current omni speaker range which don’t appear to utilize a Walsh driver. Instead, utilizing, what appears to be a normal cone driver, presumably, to dramatically lower speaker cost.

I’m particularly interested to know whether the horizontal polar-pattern at the highest frequencies of a cone driver are, indeed, radiated 360 degrees from the back-side of a vertically and inverted mounted driver, as seems the presumption. I read one of Ohm Acoustic’s omnidirectional driver patents, which indicates that, what appears to be, a normal cone driver radiates 360 degrees horizontally from the back of its cone up to at least 8kHz, where it is then crossed to a tweeter in the patent. The driver in the Ohm patent is not depicted as, nor specified as a Walsh type driver. A Walsh driver clearly looks different in design than that shown in the patent drawings, and also is easy to picture as naturally radiating 360 degrees over its full frequency range.

Good morning,
Unfortunately I broke the shaft from 1 of the rotary switches on the crossover.
Who can tell me the both types of rotary switches (positions, poles)?
The current rotary switches are from the Lorlin brand.
Are the shafts changeable without de-soldering?

Many thanks in advance for the replies!
Eric
Netherlands

I proposed to meet every other Saturday afternoon to meet, greet and swap parts and advice.

Let's start with

May 26, 2012
Tim Horton's @ Sheppard ave, east of 404 exit
let's say 2pm or so?

-joe

BA1 FE as Line Stage or Diy FE2022

Hi everyone
Anyone have schematic driagram of sub8003-AS ll?help please thank you 🙏

Hello to All,

My member name is hkskw.

I'd just registered with diyAudio a few days.

I knew the existence of diyAudio several years ago. A recent post pushed me to register because
it's so well written and invaluable to me.

I love music and audio and I hope to learn from all experts here in diyAudio. Thank you!

Hello everyone im Tej, im 18 and i joined this website because i want to fix my dad's old JVC Nivico amplifier.

I finally put aside enough cash to upgrade my 6 year old Emotiva BasX A-300 amp. I want to try a Class D amp this time. My choices are Hypex Nilai DIY Kit, NCX500 or Purifi Eigentakt. My speakers are Monitor Audio Silver 100 (Gen 6) which are easy to drive. My preamp is Topping Pre90.

Any input would be appreciated.

It uses an ATX power supply (or a 12V battery/car) to heat the heaters and drive boost converters for HV, including one that boosts 12V to 13.5V to get 440V from a 380V supply.

I use an EVGA 750W G2 supply: EVGA - Products - EVGA SuperNOVA 750 G2, 80+ GOLD 750W, Fully Modular, EVGA ECO Mode, 10 Year Warranty, Includes FREE Power On Self Tester Power Supply 220-G2-0750-XR - 220-G2-0750-XR

into the following:

This module gives the boost from the LV supply: 1200W 20A DC Converter Boost Car Step-up Power Supply Module 8-60V to 12-83V | eBay

This module gives me 280V for the preamp/buffer/headphone amp: DC-AC Converter 12V to 110V 200V 220V 280V 150W Inverter Boost Board Transformer | eBay

This module gives me the 440V for the power stage after boosting the input to 13.5V: MINI DC-AC Inverter 12V to 18V220V/380V 500W Boost Step UP Power Module New Hot | eBay

This works far better, and for less money than a conventional linear supply.

It powers an integrated amp with 20 tubes.

I think my acoustic guitar sounds best Mic'd. I mean, tip 'o the hat to all the piezo bridge transducers and sound hole mounted mag pickups, but I play nylon, so one of those options isnt viable. It's easier for the sound guy to just plug in an instrument, when changing players / guitars...

I'd like to mount the mic - in an easily removable fashion - directly on the guitar body. This will allow freedom of movement while maintaining a consistent distance to the capsule. That's problematic, as the guitar has sound vibration happening everywhere on its body, including the neck block / tail block. Put that with there's limited space for it to physically go, due to right hand playing style.

The microphone, of course, is as adept at picking up vibration as it is sound, so what you get for your "sound" is the sum / difference between the acoustic sound and mechanically conducted body vibrations. A hard mount to the side of the guitar would be worst case.

The microphone itself cannot be gigantic - no one's going to put an SM57 on standard gooseneck plumbing with a flange screwed to the top or side of their guitar. Though Dan Hicks did exactly that and went on TV with it.

I've been using a dynamic mic from a Shure headset. It's small and light, picks up sound from both sides like a ribbon and its plumbing diameter is small; almost looks the part. The trouble lies mostly in mounting it to the guitar somehow. It must be easily removable and quickly set up upon pulling the guitar from its case.

This is what works best so far. Basically a cylinder of soft foam Velcro mounted to the side of the guitar, in a spot where my hand wont hit it while grabbin' those strings. (Neodymium magnets would be a "stage 2" development - a pair glued to the inside of the guitar, a pair on whatever it is getting attached) The foam - apparently - works as both an isolator and damper within which the microphone floats. As opposed to a hard mount, where the mic and its plumbing stem would go tong-tong-tong upon plucking the capsule end. Another nice arbitrary resonance to add / subtract from the guitar's sound.



I'm tempted to get one of those camera microphone "shock-mounts" with the o-ring bands, but I'm afraid it'll be an instant fail endeavor. One can actually buy the foam cylinders off epay, in 65 and 100 mm diameter, for more than what the aluminum camera shock mount costs! Whatever material / scheme it is, it has to hold the mic in place during reasonable standing position stage movement and isolate, damp, isolate. This prototype performs adequately, just looks like crap. Hey, I dont have a CNC waterjet or laser, so machining precise features into light density open cell foam - I'm lucky to make a somewhat square to the part hole in it at all.

Any other material suitable? The ubiquitous Sorbothane, but I've never seen it as a foam. I suppose it'd be possible to layup a few discs of the stuff into a cylindrical shape - if I can get discs in the "shore" that'd work for this application. I wouldnt trust metal springs, as there's no damping at all in such an arrangement. A "rollup" of Sorbo sheet with thin foam filling, like a pastry?

I have built my own electronics in the past (post the valve age) and am now more inclined towards top end digital although everything starts and ends in the analogue world, but came to this website to answer a specific query about DAB.

I noticed that in an earlier discussion regarding Tannoy crossovers, someone suggested the following replacement:

Lorlin, 6 Position DPST Rotary Switch
RS Stock No: 866-0271
Mfr. Part No: CK1045

Does anyone know whether these are a suitable alternative regarding the HPD/385/8 ?

Kind regards
Petra

Hi All,

I'm doing a renovation upgrade project on my UPL analyzer.

I thought to list down all the possible upgrades one can do for his/her analyzer.

Then maybe i can also learn some new stuff from you guys.

Here is the link where i'm storing all my information (Software, DOS, Service Manuals, Installation disks, Many Photos) regarding my analyzer. Feel free to look around.

R&S UPL Audio Analyzer - Google Drive

See you soon.

Kind Regards,

Bart

Greetings, fellow audio enthusiasts. I'm here to jump into rabbit hole of DIY audio stuff.
Over and out

This is my latest audio project: an amplifier for the legendary Sennheiser HD600 headphones made with the superb 4P1L directly heated tubes in triode configuration.
Some technical information:
-output power: 0.2W (maximum power for HD600 headphones) for 0.7V input signal, output impedances 300 or 32 ohms;
-frequency band (output power 0.1W) at -3dB: 18Hz-40KHz, at -1dB 40Hz-20KHz;
-no headphones noise, at maximum volume (the headphones have an SPL of 112dB, they don't forgive anything!)
-distortions, SNR and harmonic distribution according to the attached graphs;
-no global negative feedback loop.
I chose another approach for DHT heaters and establishing the static operating point: I used constant current sources on the positive and negative branches and a constant voltage source for the tube bias. Thus, I obtain a perfect isolation of the supply heaters from the audio path that closes through them. The noise attenuation on each branch of the heaters is approx. 40dB and the impedance of the voltage references in the cathodes is around tenths of ohms, making unnecessary frequency compensation with decoupling capacitors. All of these lead to maximum power delivered to the load, lower current consumption (compared to the option of using a cathode bias resistor), high signal/noise ratio, high frequency response.
The noise reduction of the power sources was achieved by using electrostatic shields between the primary and secondary of the power transformers, electromagnetic shields with GOS steel sheet, separate power transformers for the DHT tubes, low noise regulators for the anode voltages, efficient and low noise DC/DC converters for low voltage power supplies and separate power supply for each amplifier. A microcontroller sets the start-up sequence, which includes anode power transformer soft-start, heaters soft-start, timed anode and headphone protection.
I also included a three-band tone corrector, with triodes and CCSs. It's noise floor is somewhere around -110 -120dBu and the corrections are +/-12dB at low, +/-5dB at mid, +/-8dB at high frequency. It can be switched off during listening.
To have a reference of the input signal level, I also included a VU-meter with EM84 that can be switched off, too.
It sounds great! I'm delighted and I can't get enough of listening to it after almost a year of building it. Together with the HD600, they are a perfect pair.

I'm going through a phase in my life when I want to design 3-way conventional box speakers with large (10" or 12") woofers and large midranges, where the midrange will almost have LF extension to act as the midbass in 2-way designs. Having loved the Darbari which I had since 2014, I now want to see if I can make them smaller, perhaps with less expensive crossovers, and better.

So, on this journey, I realise I am hesitant to design a passive crossover at, say 100Hz to 250Hz, which is where my crossover between midrange and woofer will happen. I am afraid the coils and crossovers will be large, and even hard-core fans of passive crossovers seem to be happier doing this one part active, and driving the woofer with a separate amp channel. I'm thinking of doing (at least) the same, so I need a 2-way active crossover.

I want to use something which I can embed inside the speaker, throw in the mains PSU and two amp channels, and basically make the speaker a standalone, powered active speaker. I'll be happy to do a passive xo between mid and tweeter. I've worked with difficult passive crossovers for the Asawari 4 and Asawari 5, so I feel more confident now that I'll be able to do a decent job there even with fairly difficult drivers. What I need active for is just the low-frequency split between mid+tweeter on one side and woofer on the other.

I've worked with MiniDSP hardware (the Darbari runs on the 4x10HD), but I balked at the idea of using a 2-in 4-out box (their smallest) for my simpler 1-in 2-out requirement. I am hoping that any active analog crossover I design will be as clean but less expensive than their 2x4HD. The 2x4HD would have made me invest USD 200 per speaker enclosure -- I'm hoping my module will be much less expensive. Also, KiCAD has become really powerful, so I thought I'll just wing it. Make my own. Fabbing a prototype PCB is also super-easy these days -- I use PCBPower with super results.

Studies
Most of my learning is from Don Lancaster's Active Filter Cookbook and Doug Self's Design Of Active Crossovers. Linkwitz' website. Rod's ESP pages. Randy Slone's Audiophile Projects Sourcebook. Plus years of trickle-down learning from everyone. I missed Bob Ellis' active xo project and group buy which happened 15 years ago, so I didn't learn much from there. I found the PDF of their builder manual online recently, but it wasn't very clear without a PCB on hand. Doug Self's book is the most useful.

No allpass filters
In my studies, the biggest difficulty I have faced is in understanding the use of allpass filters. When Linkwitz says "there's no point in designing an accurate crossover unless you also correct the delay", you tend to sit up and dig deeper to figure out just what problem he's fixing. This is one piece which doesn't show up in passive xo designs, so I never learned about them in my previous speaker designs, all passive. So I studied all I could find, took my final set of confusions to this thread, processed the helpful answers, and concluded that if I design active xo the way I have been designing passive xo, I don't need allpass filters. So, my circuit will not have provision for any.

Powering from power amp rails
I'll design the board to take AC from the secondaries of the transformer. I'll have one toroid per speaker enclosure, and this will have high(er) voltage secondaries, because they'll power the power amp channels. I'll avoid asking for a separate pair of windings just for my xo -- I'll do a voltage dropper after the bridge, on my board, and feed its output to the voltage regulator ICs. A voltage dropper is just a TO220 transistor, a zener, some R and C per rail. Rod Elliot's pre-regulator supplies the basic idea.

SMD 4-opamp chips
I took a deep breath and decided to bite the bullet and go with 4-opamp chips. My simple 2-way already requires 9 opamps it seems. Placing 5 dual-opamp chips seems just too messy in this day and age. Since many of the best chips in this category are only available in SOIC-14 and TSSOP packages, I'll provide for those SMD footprints on the PCB, and will also provide for 14-pin DIP pads so that people can do opamp rolling using SOIC-14 to DIP adapters. I personally do not have appetite for opamp rolling. If no one tells me otherwise, I'll go with OPA1604 4-opamp chips. If my opamp count remains at the current 9, I'll use two 4-opamp chips and one dual-opamp LM4562 DIP-8 chip.

SMD capacitors?
I'm not comfortable soldering SMD parts, but I think I'll use SMD for the filter capacitors, because the through-hole high quality box capacitors can be as large as 13mm x 6 mm, which is really too big when I'm going to use so many of them. So I'm thinking of using 1206 SMD footprints, the biggest there is in SMD.

Many capactors, all resistors and other components will be through hole.

The filter blocks themselves
People who build textbook electrical active filters have life easy -- they never have to learn about equal-component-value versus unity-gain S&K filters, or about the fact that they may be forced to manage the gain from stage to stage, because sometimes you may need to just accept whatever gain the topology gives you, once you fix your Q. So I'll try to make suitable provisions for these things in my schematic.

For the LPF blocks, the first component in the signal path is a resistor. This is useful because one can split this resistor into two and make a voltage divider, and achieve some gain reduction, all the while conforming to the filter formula. (This YouTube video explains it very well.) So for my LPF blocks, I'll keep provision for this second resistor.

Input, output and enclosure
This is a single-channel board, so it'll have a single analog input. I'll have provisions for both XLR and RCA, and I'll use one opamp for both these inputs, borrowing circuit ideas from Doug Self's books. I'm still trying to figure out the circuit which will let me provide both unbalanced and balanced inputs without a switch. If I add a switch, it's easy. Input will travel to this board through connectors, and the cables bringing signals in to it will be at least 2 metres long (from a central audio rack to each speaker). Output from the board will travel over internal shielded cable to power amps, so these output cables may be 12" away.

Do I need a separate output buffer? I definitely need gain control for each "way", but does it need to be active if the signal is travelling over a short internal cable to a power amp nearby, and I have control over what power amp it is?

I expect the board to be mounted on a metal plate (maybe 2mm thick steel sheet). This metal plate will be at least 12" long, and the XLR connector, RCA connector and mounting holes for this xo PCB will be near the top. Below this will be the power amp heatsink, on which 2 power amps will be fitted. Below the heatsink will be the IEC mains socket and power switch. Somewhere near the IEC and power switch will be the mounting holes for the soft start module. I'll have to find some separate mounting location for the toroid transformer. So, this metal plate with all this active circuitry will be fitted to the rear baffle of my speaker enclosure. Since my speaker enclosures are much larger than 12", I'll have space above the metal plate on the rear baffle for my passive mid-to-tweeter xo.

BSC: global or just low-pass
The BSC block is supposed to apply to the midbass branch if you're doing a normal 2-way speaker design. It's supposed to span both bass and midrange if you're doing a 3-way where the woofer-to-mid crossover frequency is really low, as in my case. So, though my crossover will be a 2-way design, I'll need the BSC block to be global, so that it spans both branches. However, someone else may want to use my PCB for a conventional 2-way speaker (heck, I myself am tempted for one of the Asawaris maybe), so I'll keep jumpers. You can take the PCB and choose which jumper to add, to keep BSC global or just for the low-freq branch.

I won't provide trimpot-adjustable BSC. I'll provide for a 4-way DIP switch, so that you can select 0/2/4/6dB of compensation. BSC is one attribute which I believe may need adjusting even after a speaker design is finished, because it depends on room placement.

Optional LT
I'll provide an LT block, but you may not want it if you are doing, for instance, a ported design. I love sealed bass. I'll be highly likely to use it. I'll provide jumpers, and you can add the appropriate jumper to bypass the LT or use it. In fact, one of the biggest reasons to go active for my 3-way speakers is because I want to use sealed bass, which often requires LT. I aim for F10 at 20Hz, with a Q of 0.6-0.7.

No notches
Notch filters are common in complex active filters, but I'm not providing for any here, because I'm primarily aiming to use the circuit for woofer-to-midrange xo, at quite low frequencies. For this xo, there will not be the need for any notches in most cases. Those blocks are usually needed at higher frequencies.

No spreadsheet for easy calculations
It has been a tradition that active analog xo designs have come with a handy spreadsheet (or even a Windows executable, for Rod Elliot's board) so that you can just say what your Fc is and you get the R and C values for an LR4 xo. My board can be used that way if you want, but I don't intend to use it that way, ever. I expect to design and optimise my xo in an active xo simulation software like VituixCAD (or SoundEasy/LSPCad if you prefer) and tune the knee frequency and Q to get exactly the phase-aligned acoustic curves I need, after loading the actual SPL measurements of my actual drivers on my actual front baffle (a lot of actuals there but I'm trying to make a point here). I have no use for textbook electrical filters.

So, if you want to use my circuit boards, you'll need to use my design approach with active crossover simulation software, or you can use one of the spreadsheets from somewhere else.

No trimpots
I don't have trimpots in my passive xo, and the speakers I've made sound lovely. I have no idea why I should need gain control trimpots for my active xo. (Modern crossover simulation software is next only to Hogwards magic, isn't it?) So, I'll provide gain control trimpots in my circuit, but I'll also provide places for a voltage divider with two static resistors, so that you can play with variable gain if you want, but you can later remove the trimpot, measure the two legs, and replace the trimpot with the static resistor pair. Or just keep trimpots in permanently, it's your choice. I'll make provisions for top-adjusting multi-turn Bourns trimpots -- maybe 4-turn and 12-turn options.

Cascade for 3-way?
Two of these boards can be cascaded for a mono 3-way design, I guess. I'll try to provide for a mechanism for supplying the regulated power rails to cascaded boards from a single board, so the PSU circuit can be populated only on one board. That way the tall heatsinks on the TO220 pre-regulator transistors, the 3-pin voltage regulator ICs and the supply filter capacitors can all be on the topmost board and other boards can be stacked below it close by. Of course, if you need anything other than a simple 4th order filter for your xo (my mid-to-tweeter xo often do), then this board won't be of much use for your 3-way or 4-way designs.

Github
The design files will go into a public repo at GitHub. Finally, with GitHub and KiCAD, we have a full open source suite of systems and products which allow us to do open hardware without having to attach zip files to posts in a forum like this. With Git, both CAD files and associated documentation (README.md) will be version controlled with Git tags, so you just check out a specific revision. All files will be published under a Creative Commons open source licence.

I've attached just a top level block diagram. Each block here is an opamp.

Will need your help
Will look for inputs for all aspects. I'm no expert.

PS: is there any way to keep the first post of a thread permanently editable? If yes, I can keep updating this thread as the project progresses.

To introduce myself to this lovely community and my goal is to learn stuff for this project I’m doing.

Will probably end up outsourcing the solution to my problems but let’s see where this rabbit hole takes me.

Over and out

Hi, I’m an avid second hand and flea market enthusiast who love listening to music, preferably on vintage British gear found for bargain prices.

I hope you can help me trying to mend some older amps and speakers as well as guidance trying to build my first set of speakers.

I have learned so much from this community over the last 20+ years, yet never became a member. I wouldn't know who to thank after such a long time.
But those that helped would include BLH builders and Full Range driver users/modifiers.
Thank you!!
Ward

Hello all


I need the repair manual for Sumo Andromeda II MOSFET amplifier

Was working fine in 2011, now it's blowing the output fet's with no audio connected. Q310 & Q410 are also getting hot. Power supply seems to be doing fine (~45vdc).

Here is yet another inrush current limiter. The circuit is straightforward, and component values need not be precise. Also attached are two plots: one showing the line current with the limiter and the second without the limiter. Needless to say, the large current/voltage transients encountered without limiting are not good for the life of the filter caps or other components.

I have implemented this circuit and variants thereof for both inrush limit and output connect, where the latter was used to prevent turn-on transients from appearing at the amp/preamp output. The circuit also implements asymmetric turn-on and turn-off characteristics, such that a transient line power loss results in a reset and full delay time to relay close.