Hi there folks,
I am repairing a friends Yamaha active subwoofer. It uses a Sanyo STK power module. This 60W module has a Tc max of 125 deg. Celsius.
The original power module is a direct short across V+ and V- . The Sub. design has no 'finned heat sinking' and only uses the sheet metal
control panel as cooling. I am assuming that the power module 'blew' due to being pushed very hard at a high temperature.
There is room very close to the module to mount a 240V thermal switch. My local electronic parts shop has a 100 deg. (trip) thermal switch.
My question is >
Is 100 deg. too low, too high or just right in such an application ???

Parts and tubes have overfilled basement shelves and I was "ordered" by my better half to clean up....

The driver and output stages are built with parts I found while I slaved.....

Psu was made for a 50 se amplifier some years ago. 394a-lclc, Dave Slagle's lc modules feeding Rod Colemans filament regulators. The high voltage is way to high for the driver and output tubes, so I chose to drop the excess adding two simple shunt regulators.

The SFR E130 is a really nice tube. Pretty much similar to the rs 242, but lower internal resistance. Driving it into a2 yields just below 4W.
I had some concerns that these amplifiers would lack power to drive my speakers properly, but for daily listening they are more than powerful enough. The attached measurement is taken at normal listening level. In the middle a Linestage with VT-25 (separate psu not visible). It can be configured as only AVC (Dave Slagle/Bent audio modules) or 4:1 or 2:1 stepdown.

Dear members...

Perhaps someone has or can give a suggestion how to reproduce decals (stickers) on transformers and capacitors in power amp part of Sansui receiver G-33000... Of course - there will be nice to have a vector file to produce them, but perhaps someone has nice photo or file as a pictures of those decals...

Thank you,

Boris

Hello there folks,
I am repairing a friends Yamaha active subwoofer. The amplifier module (CHIP) is a 60 watt Sanyo STK device.
The maximum operational thermal rating = 125 degrees Celsius.
With no cooling fins, the sub. design uses only the sheet metal of the control panel for cooling.
I am fairly sure the reason the Chip Amp/module blew-up was heavy drive at high temperature.
There is room close to the Chip Amp/module for me to add a 240V thermal switch.
My local electronics shop has a 100 deg. C thermal switch.
My question is >
Is 100 deg. too low, too high or just right for such an aplication ???

Hi all,

I really want to try a source-o-dyne phase inverter, like Gnobuddy's ones, however I'm unsure about the MOSFET biasing.

My power will be plus 300VDC - 0V - minus 300VDC , and the MOSFET will be the 2sk2700

How do I work out:

1/ the ideal current thru the MOSFET?
2/ R1/R2
3/ R3
4/ R4
5/ R5

Cheers 🙂

Schematic courtesy of Gnobuddy

Selling low hours High values matched pair of Ken-rad 2a3 black glass. Values on the box picture. Sound extra sweet although they have some hiss compared to actual tubes production. This pair has soul for sure. Sell for 350 Eur + shipping

Hi all,

I am seeking firmware for the Yamaha DVD-S2700.

I purchased the Yamaha DVD-S2700 completely dead. I've invested a significant amount of time into it, and although I've resolved some issues—such as
1. fixing the dead power supply
2. replacing the non-functioning tact switches—there
3. dead laser that I've replaced

Now the DVD reads all of the CD/DVD/SACD/VCD discs that I have, but I still have two unresolved issues:

1. It does not respond to the remote control. I have tried both original DVD15 remotes and a universal remote. The IR sensor seems to be functioning correctly because I measured voltage at the output of the sensor, and there's a noticeable change after pressing a button on the remote.

2. The HDMI output is not functioning (I have tried to reset HDMI according to service manual - but for a half of second it blinks "HDMI RESET" without changes)

I assume that perhaps a firmware update will help, but I cannot find firmware for this device anywhere. I have contacted Yamaha without satisfactory results. Does anyone have firmware for this device?

Best regards,
Sebastian

Hey everyone

i plan to use dual Beyma 12br70 per side ala Amphion Krypton woofer arrangement ( woofers mounted on the each side panels)

dual 12br70 is about 99db/98db. I therefore need a mid of about 97db/96db

xo first order 160hz/1300hz, so smooth roll off for the mid is critical

many thanks

Hello hello,

I have several files tapped horn profiles that i would like folded and turned into a CAD file to make it easy to cnc.
The horns are quite simple. Straight taper between throat and outlet.
The larger versions to be separated into parts to maximise cnc cutting.
happy to negotiate price so both parties win.

Short story. 15-20 years ago I removed plastic from capacitors in search for better SQ. No components, please 🙂 . I have to replace these capacitors but need help to identify ratings/values for: C18-C23. See schematics.



Yes, I know I have "vandalized" an great Copland amp, but I hope I can restore it with some help. Thanks.

I am trying to fix the US amp Merlin md3d amplifier that I believe it to be a Class A B. If I put one Probe on either the B+ and then the other probe anywhere else in the board it measures 12 volts. if I take that probe off and put it on the remote terminal the same thing occurs...... 12 volts everywhere. if I switch the probes in the opposite direction it shows negative 12 volts. I do not remember getting any other voltage reading other than 12 volts. anywhere I measure whether it be the power transistors, either side of the Transformers, all three legs of the transistors, i mean everywhere 12 volts. ...everywhere.

Hello

i wanna build a rectifier board for my DIY dac, since i think this is the better route with better parts than buying chinese ones..

did people around here test different stuff and know what sounds or is best?

i have a "audiophile" thel power supply here which seems to have 12x 3300uF for smoothing and dedicated diodes, is this the way to go?
is just LOW ESR important?

So I've been breadboarding some preamp circuits and wanted to try some "battery tubes" so, of course, the 2P29L caught my eye. Rather than posting to the 4P1L megathread I thought I'd start a new one.

I'm pretty much a copy and paste builder, not a designer, and my technical knowledge is limited, unlike many of the posters here.

I build low cost, "bang for the buck" stuff. So no expensive plate chokes, vibrator loads, output transformers or trick Rod Coleman filament supplies. Just keepin' it simple using a very basic circuit with parts I had on hand. It's a budget build not a state-of-the-art design.

I used a lower voltage PT at first, which worked OK but I remembered the rule of thumb that says a plate load resistor should be 3 or more times the plate resistance. So that meant using a 15k resistor. To accomplish this I needed more supply voltage so I changed the PT.

The current PS is built around a NOS Halldorson PT I picked up years ago at an estate sale. Because the voltages were getting a bit closer to the 450v rating of the caps than I like, I added a 500 ohm resistor between the rectifier and the first cap. It's definitely not optimal but it's good enough for a breadboard.

The 6BY5 is a dual damper diode which I chose mainly for its soft start characteristic and because I have a bunch. Plus I already had one set up on the breadboard. A different rectifier with more voltage drop might be a better choice and would, perhaps, allow me to ditch the 500 ohm resistor.

Four AAs supply -6.4v of bias to the grid.

Before switching to the 2P29L, I was experimenting with the 1LE3 and using a single AA on the filament. That tube only draws 50mA so the battery lasted a good long while - roughly 24 hours.

Since the filament current is 150% higher for the 2P29L I decided to try a cheap ($3.55) AC-DC regulated switch mode supply. The output is 3.3 vdc and I'm using a 10 ohm resistor to drop it to 2.1v.

From what I've read, I wouldn't be surprised if this filament supply didn't look too good on a scope. I don't have a scope, all I have is my ears.

I started with batteries, then went to battery in one channel and the AC-DC in the other, then both to the AC-DC. I couldn't hear any difference at all. Not saying there isn't any but it wasn't audible to me.

I added a 6800 uF 6.3v cap after the 10 ohm resistor to see if some filtering would be noticeable. I haven't listened to it with the cap much yet. I'll A-B it next week and see if I hear any difference but I figure it can't hurt whether it's audible or not.

I'm not good at describing what I hear but I find it very detailed yet it doesn't exhibit any harshness. And microphonics are not a problem.

I've used the tube in stock form and also with the aluminum shield removed. The nude version looks more familiar - like a small version of a 7868 - but there's essentially no glow at all.

Here's the current schematic. Comments and suggestions welcome, of course.

Hello folks,

I recently got my hands on an EL84 PP valve amp output stage chassis (from a Dynatron Cavalcade GR1, I believe) and would like to turn it into a guitar amplifier.

Can anyone recommend any resources that would help me design a preamp for it? Or would it be better to just copy an existing design?
I have attached my attempt at tracing the circuit, along with some pictures of the chassis (please ignore the duplicate heaters).

Also, just out of curiosity, what are the two EL84 plate capacitors for (C7 and C8 - the two silver caps in the lower right corner)?

Many thanks,
Alex

EYE PATTERN

I managed to get the eye pattern on my oscilloscope( thanks to members on this forum ). I made a YouTube video above.

Now I get a lot of bouncing on the eye pattern and it gets worse with the last tracks on the cd.

I have tried moving the pots other than the laser output but don’t see much change.

What am I doing wrong or is there anything else I can do to fix it. Also I really need an angled pot adjusting flat screwdriver as when the last track is selected there is no room for a straight screwdriver to fit from the back.

I can’t find the above anywhere so I thought I’d ask on here .

Thanks
Andy
Uk based

Good morning to all!

While I'm wading through my various other things, I found one that's bugging me:
the build of a AVC, with autoformers (23 positions) I got from a serious guy in germany.
He's not very responsive though, thus I'm asking for confirmation here:

The correct connection of the Autoformer to the switch seems scary easy. So, according to the schematic from a different place, is it

• first wire to input hot,
• 2nd - 23rd wires to the positions 2 - 23,
• switch output to next stage/output
• in/out GND tied to AVC #24

While writing this, it seems to make sense, like being pretty close to the schematic.
Right?

Hi,

does anyone have the repair-manuals for the Denon hifi parts

• UTU-F88(tuner)
• UCD-F88(c.d.)

Thx

Hello can you please indicate me which Brand and Model have used a BSC in their filter.
Thanks

We have a small team that is building a DIY Curve Tracer. Not a Tek577, but a lot better than anything we found that comes close. We are close to the final stages and have a fully operating CT that I'm making measurements with.

If you're interested, have look on my blog. Eventually everything will be shared but we'll wait until we have finished the project.
This describes how we came to the design:
Paul's DIY electronics blog: Building a Curve Tracer - Version 3

Here is the final desciption of building the Curve Tracer:
https://www.paulvdiyblogs.net/2022/06/the-vba-curve-tracer.html

My blog is not great for handling questions and replies, so please leave them here.

Enjoy!

greetings !
I'm posting this topic on this forum hoping that the subject doesn't spill over 🙏🏻

I am doing purely intellectual research which has no specific goal other than knowing it, I would like to be able to have the name of the hf\coaxial compression driver
as flat as possible with innovative technologies whether on the phase whether on the dispersion or other

My stone in the building only has the 4590 of BMS
never seen such a smooth curve over such a large range, I am waiting for your documentation, link, on other compression driver

Hi, does anyone know where I might be able to get some of these? My deck needs two of them. They are photo-couplers for an auto calibration circtuit.

I put together a circuit which is mainly the combination of two circuits I found on websites.
One is for inversion (inverting the left channel, combining it with the right and getting the result).
The other is a center channel.
The designs appeared in several places and seemed to be recognized as correct.
So all I really did was join them and add a bulb and a few switches.

When I connect a small 8 ohm speaker all I get is a hum. And this occurs even without input.
I am using two LM386 ICs which are mounted in sockets (to avoid soldering the IC leads directly).
They're tiny so I had to take care not too short any.
The connections have been tested for continuity (with the leads) and discontinuity (among the socket leads).

Does anyone have any ideas how to go about debugging this?

I got two Alpair 10p full-range drivers and plugged them into the woofer holes of old speaker boxes I took apart. I took the old tweeters out and left a big hole in the box. I also took out the bass port tubes and plugged up the back hole. So now the tweeter hole in the front is like a bass port? I thought these couldn't possibly sound good like this and put them in storage for a while. I just pulled them out and plugged them into an old Denon receiver and was pleasantly surprised by the sound. How is it possible this sounds half-decent?

Some of my 6AG5 tubes have some tiny dark lines around the cylinder section of the glass. Mainly a particular batch of Sylvania tubes. My rca and GE 6ag5 just have clear glass, and so do my chinese 6j3 (modern equivalent) When i look under an LED scope, i can see that its a bunch if tiny black rings on the glass.

Picture of one of the sylvania next to a chinese 6j3 to show what im talking about. Were NoS tubes and they all look like this one, and im pretty sure i've seen dark glass on tubes before.

What is it? I'm having trouble asking google and search correctly apparently.

I also think the sylvania have a nicer sound to them then my GE or RCA. I imagine it wouldn't have anything to do with this. Would it?

Hello,
From 1988 pioneer A-443 amplifier.
10000uf Nichicon capacitors show 9600uf are still usable, is this possible after 36 years?
Should I still use these? My tester says there is no problem and the ESR value is great. I am confused.

Hello,

I am looking for a Mark Levinson 383 Control Board to purchase. If you have one for sale please send me a message.

Thank you.

For background, I'm a professional hardware design engineer with over a decade of electronics design experience.

I've been working for a couple months on this DSP headphone amplifier using the following major audio blocks:

• DAC: AK4493S
• Amp: OPA1622
• ADC: AK5572
• DSP: ADAU1467

Audio quality measurements are quite close to the DAC/ADC chip specifications, actually the chip specs are beyond the capability of the audio test equipment I currently have access to (Prism dScope III).

I have two extra units from my prototype build available, would be happy to provide at cost ($375 shipped to USA). The GUI design is still very much a work in progress (using LVGL & SquareLine Studio), so buyer definitely would be able provide some input to that. Firmware updates are very easy with computer + WiFi connection to the unit.

Any Russco or later 12C owners out there with bearing oil recommendations?

I'm finding I need to run my turntable for a while for the speed to stabilize. When I completed the rebuild I used some fairly heavy weight oil in the bearing well. Once warmed up it sounds great.

It also has a tiny bit of audible rumble when the needle drops. Any tricks on reducing that?

eso

These are the best Capacitors you can find for power supply.
With their very low ESR of 5 mOhms and long life of 12000 hours you can not go wrong.
I got them from Digikey some time ago for a project but couldn't make it. They are new unused.
Part number is B41456B9479M000
These cost around $100 but I can give them away for $70 each

I have taken my Philips cd880 from the attic in a case of cd nostalgia (and because I’m frustrated with the prices of vinyl nowadays). The player is 36 years old by now and stock condition.

The unit fires up and plays without problems really, although I find it a bit dull sounding.

Given it’s age, it’s probably a good time for a recap operation. Is there anybody who could share a BOM for a full recap?

Thanks!

https://www.parts-express.com/Dayto...cwp6mZ1g6WVuAgRoj4iS5pTbRGxpS4hiohA0CgDPZf458

Just saw this on their site. Looks to me like a pretty attractive price considering the parts used (assuming you find the cost of the parts individually to be reasonable). Surprisingly no measurements are provided? At least as far as I can tell. Anyways, thought it might interest some

Hi I have made several posts now........have I passed moderation? Very keen to have a number of discussions........many thanks in anticipation....

I have a pair of Tekton Double Impacts and I am trying to understand the details of the tweeter array. I created the attached schematic from my pair.

Can any of you crossover gurus break this down and explain the functions of circuit?

Just starting to layout my headphone amplifier using the 4 x OPA1622, this project started from needing a headphone amplifier that could drive 4 x 32 ohm headphones from a digital source and needed or I wanted it to be battery powered ; my family enjoy watching movies together and headphones are our choice for listening and so this project came about.
The design will have individual volume control for each outlet and have 3 x sources of audio available, USB Audio Bridge, Optical SPDIF and stereo balanced analog inputs as well as balanced outputs all using mostly TI.com ICs. DIR9001 for digital interface, PCM1794A DAC, OPA1622, OPA1656 and OPA1637 for balanced output drive. Volume control can be selected for the XLR outputs or jumper out on the main PCB.
battery management is using TI.com BQ25616RTWR IC.

1)

1x Twisted Pear Audio "Hermes" + "Cronus" used - SOLD
Asking 50€ + shipping costs and any fees.

2)

1x Twisted Pear Audio "Hermes" + "Cronus" NEW, unused - SOLD
Asking 70€ 60€ + shipping costs and any fees.

3)

1x BeagleBone Black, Rev. C, 1GHz, 512MB, used - SOLD
Asking 30€ + shipping costs and any fees.

4)

1x BeagleBone Black, Rev. C, 1GHz, 512MB, NEW, unused - SOLD
Asking 40€ + shipping costs and any fees.

5)

1x SanCloud BBE WiFi - V1G - "BeagleBone Enhanced" (1GB DDR3 RAM...), NEW, unused - SOLD

https://www.sancloud.co.uk/beaglebone-enhanced-bbe/

Click to expand...

Asking 60€ 50€ + shipping costs and any fees.


If prices are off let me know or make an offer.

Please contact me through PM.

Does anyone have a circuit board for a paradigm pdr12 subwoofer? If so I would be interested in purchasing it for a reasonable price. Thank you.

Keep down-sizing.

Here is a pair of NIB Tango Hirata TC-10-130 chocks in die cast cases. Still sealed in the original package with documents. This model can be connected in series or in parallel to offer two combinations of inductance and DC current rate.

Please note that these two chocks are functionally identical but different in colors. When I visited Akihabara the electric town in Tokyo, the shop had two available in different colors yet I did not have time to wait for special order.

Specs (according to product insert; see photo):
Primary Inductance: 10H/130mA (Series); 2.5H/260mA (Parallel) at 5V, 50Hz
Max DC current: 150mA (Series); 300mA (Parallel)
Dimensions W56mm D50mm H80mm; Weight 0.8 kg
Color: 1 Metallic Gray; 1 Beige-White

Asking $380 for a pair or $220 for one piece. Buyer to pay actual shipping+handling from Boston, MA, USA.

Hi all. Last time I posted here was probably 5 years ago. Most of the time I come here to read. I can't find much info about the JLH 1969 MOSFET variant except one instance mentioned on the huge "JLH 10W" thread. Someone said this variant should have its own discussion thread but I can never find it. I am posting just to share my experience and not intend to "stir up" any dust.

One day I was browsing Aliexpress for something completely unrelated but then I noticed this board from China. They call it 1969M. I think M stands for MOSFET as output device. I read the description and it says to adjust Iq to 30mA and it will produce good sound. I have built a JLH 1996 dual rails many years ago (I think I posted it in this forum). Using MJ15003 as output and tested at different Iq, definitely bad sound if I set it at 30mA. However, curiosity set in. Paying less than $11 US shipped, I have nothing to lose and ordered them.

The boards came and I put them to test at the bench. Used a bench supply of 16VDC, I tested one board at a time. First board no problem set to 30mA and got sound on a test speaker. The second board's current adjustment was a bit challenging. The idle current oscillate. I short the input to ground and was able to adjust to 30mA and also got sound on the test speaker.

I then mounted them on an aluminum L bracket with a spacer at the bottom from the wooden board. The L bracket acts as the heat sink and front panel where the volume control is also mounted. I power the boards with a 24VDC LM723 analog regulated power supply. I also connect a ground wire to the L bracket so the boards will not become an AM radio. With the 24V supply, I have no problems setting the current to 30mA. 16VDC was probably too low.

I then connected them to my pair of JBL2800 which I am currently using. I didn't expect much but the initial listening impression is very promising. Afterwards, I replaced the input coupling caps with ERO MKT1813 2.2uF. After a day of two burn in for the caps (some of you disagree on coupling caps burn-in and I'm not going to stir up arguments here), the amplifier sounds really really good. The original input caps were not good, especially with piano music. The MKT1813 is way better for the job.

This amp sounds "liquid". I had another MOSFET amp years ago and this one reminds me of how MOSFET amp sounds. When I mean "liquid", it sounds like a very very small "reverb" effect is in place. The sound stage is wide and it fills from end to end of the room. The L bracket barely feels warm with a comfort volume level for a living room of about 15x15 ft. I have a tube-03 preamp with the Russian 6J1P-EV tube as the preamp of this amplifier. It seems to be the right mix for me. I know 30mA Iq definitely is not class-A but I have also not heard a solid state class AB amp that can sound this good so I take it. I do have tube amp and class D amps and I can say this amp is different. You know it is definitely not tube nor class-D but it is very comfortable to listen to. I can fall asleep while listening to this amp.....

[My source are modified (coupling cap) Sony CD player and Amazon Fire 7 streaming Pandora.]

As there are some Naim experts (mr. Ian) here i wanted to ask somethings about a project i'm wanne start. I can get some original power boards for free. I want to put them in a nice Modus case with nice styling (Naim knobs and fonts etc). As you can see there is some work on it. I wil rebuild them. For a PSU i am thinking of a simple bridge with 20.000uf per rail just like the 140. For a transformer i think i can use something from 25vac to max. 27vac?

I'm also going to apply some acoustica.org mods like remove current protection circuit and coupling cap and maybe some Welwyn resistors in the signal and feedback.

But can you tell me something about these boards and if i'm overlooking something about this PSU or project?

My second ask within this build is the pre. After reading a lot about this i'm have my mind set on a NAC72 witch i also have. I'm gonne use a Sjöström reg on it. And maybe leave the buffer out. The relay i'm gonne leave out for sure.

But looking at the circuit i see a lot of coupling caps. I have caps in my sources. So are there any objection about leaving some out as you can see in my drawing?

How about friends, initially this amplifier came with a short in the fets of the output stage, it is recovered and we proceed to check the pulses that a csc3120 sent, but they are not reflected and since I don't see a pulse I change the IC for an irs2092s and it tries to boost but it does not succeed and when checking the output terminals it detected voltage, I removed fets and ic and I still found 2.4v, I do not think it is normal, does anyone have experience in this type of amplifier it only has one ic drivers csc3120 for 6 fets, thank you, regards.

(Due to weight – local DC/MD/VA Metro Area only).

Available for sale is the North Creek Audio Echo Speakers system– 3.1 speakers (LCR + free sub).

The cabinet construction was overkill, all Baltic Birch plywood with 1.5” baffle. They are finished in beautiful teak veneer with three coats of Waterlox tung-oil finish.

They were lightly used in a bedroom system, never pushed hard. I had designed the Left/Right to be wall-mounted (using a recessed French cleat system) – but they work just as well on speaker stands. T

hey are sealed speakers and are meant to be used with subwoofer. I can include a passive mini-subwoofer to go with these (built using the Tang Bank W5-1138MF - basically Voxel subwoofer) – also finished in teak veneer.

They are 10/10 in both functional and physical condition. Also included in the sale are a spare pair (2) woofers (just in case you ever damage them and need a replacement).

I’ve included horizontal polar measurements from 0-80. This measurement was at 1 meter, response further away was even more smoother.

So you are essentially getting:

8 – North 13W-06S woofers
3 – North D25-06S Silk Dome Tweeter
1 - Tang Band W5-1138MF woofer

Everything enclosed in beautiful teak Baltic Birch cabinets.

I don’t know what to ask, but I was thinking maybe $250?

Single unit with original dia. $150

Lowest cost/performance ratio would be greatly appreciated though I do not mean cheap, has to sound great. Not apposed to going to a smaller driver as long as we can get down to fairly low in bass output with a single driver per side.

Going into the ceiling 4 ft above the bed into a space approximately 16x30x6" filled with fiberglass and has two 3" openings to on two sides into more air space.
I am looking into a low cost but great streamer/dac/amp combo or possible separates, wired to ethernet so no wifi or BT needed. just needs to sound very nice, laid back, etc, will consider one of the little units from China with tubes even if a hybrid, would look cool and my wife loves tubes as much as I do.

Any ideas would be greatly appreciated and of course I will start doing a lot more research than I have as just came up with this idea instead of using a BT speaker like we have been doing.

Edit: I realize I will likely want a pretty high QTS driver for this.

Thanks,
Rick

Since Vbe splits amplifier power supply voltage in half, can you get by using transistors rated at half of that voltage?

For example, let’s assume power supply voltage -37V 0V 37V (dual voltage). Now, can I get by using 40V VAS transistor?

Thanks!

Hello, I have these handmade speakers, what kind of cabinet do you think they can be used in? They will play up to 500 Hz

I've got to build a 1541 based DAC just to see what it sounds like. I came across a blog or website that I cant find again. It was a single 1541 chip on a green pcb and the person had like eight or so of the PCB's stacked on top of one another. Has anyone seen something like that?

If not, what is the best layout available today? I'd like to build one with balanced output as well.

hi a friend of mine build an amp 50y ago and now he is getting humming noises after a while of usage. he measured the power supply and got 10v on one and 12v on the other branch.

initially he wanted to buy a new amp for 50E but i told him to repair the old stuff. probably a caps job would do.

starting this thread as an invite for my friend eventually he will register and join us.

check the photos.

now the question is what could be causing the humming sound?

Looking for a pair of working F4 boards that are fully stuffed or possibly a kit with the Jfets, Mosfets, and boards.

Wanting to buy or could make a trade offer.

What can I expect out of these and what are the differences and which one would you go for? thank you!

SBA Gema
https://sbacoustics.com/product/gema/

Visation Nimrod
https://www.visaton.de/en/products/3-way-speakers/nimrod

Troels Gravesen Seas/Discovery 3 way MkII
http://www.troelsgravesen.dk/Discovery-3WC-mkII.htm
http://www.troelsgravesen.dk/SEAS-3-Way-Classic-mkII.htm

Linton Heritage
https://www.wharfedale.co.uk/linton-heritage/

Considered one of the best supertweeters ever made and getting hard to find. Good condition, appears to have original dia assembly measuring around 4 Ohms for 8 Ohm nominal impedance. $485

CL - Firma, audio project by Claudio Gandolfi,
08 - 3FE25 Faital-Pro driver diameter, 8 cm,
A2 - Project code, dual 3FE25 full range, 5 emissions: 2 x direct, 1 x omnidirectional, 2 x multiTL.

The characteristics of the listening environment are very important for the quality of playback. With MDD technology, part of the energy emitted by the speakers is used to generate secondary sound fronts, the spherical fronts generated by diffraction are coherent, delayed and optimize interaction with the room. The emotions produced by listening to recorded music can also be obtained without treating the room acoustically and with economical broadband speakers. MDD Multi Delays Diffraction. The multiple emissions simulate three-dimensional sound sources, the delays optimize listening in environments that are not acoustically treated, the diffraction makes the speaker omnidirectional at all frequencies.

Acoustic loads are made with multiple waveguides. Each individual waveguide adds delayed, coherent secondary waves to all sounds even if the recording was made with microphones positioned in less than ideal locations. The primary and secondary waves are reflected by the environment and reach the listener who perceives them as compatible with a three-dimensional source present in the room. Omnidirectional emission in a reflective environment increases the effect of the waves reflected from the listening room. When the reflections of the recording room are reproduced due to the Haas effect, the brain perceives them as a continuation of the previous signals. The succession: primary wave, coherent and delayed secondary waves, reflections from the listening room, reflections from the recording room become a single sound for the brain that is easier to interpret and pleasant to listen to. It decreases the time needed for memory to decode sounds and increases the time available for imagination. Playback is similar to listening to instruments live in your room. It's not the most faithful conditions to the original recording but it can be a lot of fun. The listening area is large and you can better follow the music from every point of the room.

The project uses the 1a-direct (over 100 waveguides) and MDD3ZC350 V2 (5 + 7 waveguides) prototypes, each channel has two 3FE25 drivers from Faital-Pro connected in series. The 3FE25 driver of the 1a-direct prototype has a direct front emission and a rear emission with multiple mddTL transmission lines. The 3FE25 driver of the MDD3ZC350 V2 prototype has a partial direct front emission, a multiple omnidirectional front emission mddOmni and a rear emission with multiple transmission lines mddTL.

The single waveguide fractions the sound energy emitted by the driver cones, isolates it from the listening environment, transports it to positions distant from the driver, re-emits it into the environment with a delay and maintaining coherence with the emission primary of the driver. The output size of the waveguides is 1 - 2 cm therefore, due to the effect of acoustic diffraction, spherical sound fronts are generated up to almost 20 KHz.

The sound quality is excellent but the implementation is complex. There are many components, waveguides mounted with mechanically disadvantageous levers can generate unwanted vibrations worsening reproduction. The compression chambers of the waveguides must be airtight so as not to reduce the low frequency response. It is not a suitable project for those who want to start with DIY. I'm already thinking of a new project with the same audio characteristics but simpler to create.

time domain​

From the listening point you can see dozens of omnidirectional emission points, the sound fronts generated at different points in the space arrive directly without reflections. In MDD (Multi Delays Diffraction) technology, multiple, coherent, delayed and omnidirectional emissions make the sound scene three-dimensional, masking the unwanted effects of reflections in the listening room.




From the step response graphs you can understand the complexity of the acoustic signal emitted by the pair of 1a-direct prototypes, MDD3ZC350 V2. The measurement graphs are further complicated by the presence of reflections. In the theoretical response design I consider an impulse made by a single half-wave at 1KHz (0.5 msec), for simplicity I neglect the reflections and assume that all waveguides have a flat frequency response, The time axis is realistic, the amplitude values are indicative for a qualitative analysis.

1. The first sound pulse (green) that arrives at the listening point is the one emitted by the 1a-direct prototype. The 3FE25 driver is positioned approximately 1 meter high.

2. The second sound pulse (green) is delayed by approximately 1.1 milliseconds and arrives in phase with reduced amplitude. It is output by the MDD3ZC350 V2 prototype driver. The amplitude is reduced because part of the sound energy emitted is sent into the mddOmni frontal acoustic load.

3. A series of five sound pulses (red) follows. The pulses are in phase with the first, they are coherent and with progressive delays between 1.4 and 7 milliseconds, the amplitude is reduced. It is the multiple omnidirectional emission from the mddOmni front load of the MDD3ZC350 V2 prototype.

4. At the same time, a series of 180 sound pulses (blue) emitted by the mddTL acoustic load of the 1a-direct prototype arrives. The pulses are in counter-phase, they are coherent and with progressive delays between 1.8 and 3.7 milliseconds, the amplitude is further reduced.

5. Next, a series of seven sound pulses (blue) arrive at the listening point. The pulses are in counter-phase with respect to the first, they are coherent and with progressive delays between 7 and 10 milliseconds, the amplitude is similar to that of the pulses emitted by the mddOmni acoustic load. It is the output from the mddTL rear load of the MDD3ZC350 V2 prototype

All the sound impulses generated are synchronized, they are emitted by the two drivers connected in series and crossed by the same electric current, the forces acting on the cones are proportional to the current. The delayed pulses emitted by diffraction from the mddOmni and mddTL waveguides are consistent with the driver output, the delays depend only on the length of the waveguides.

3D effect​

MDD technology generates coherent and delayed sound fronts to simulate the presence of the instrument being played inside the listening room. An instrument emits multiple sound fronts at different points in space at the same time which reach the listener's ears at different times. With MDD technology, the multiple emission points of secondary waves simulate a virtual volume of the instrument being reproduced, this also facilitates the recognition of the sound emitted at any point in the listening room. There is a 3D effect generated by the distribution of the waveguide outputs in the orthogonal directions of the three axes X, Y and Z.

The setting is an alternative to point source emission which optimizes listening in a limited area and in acoustically treated rooms.

anti Haas effect​

The Haas effect (precedence) occurs when two identical sounds arrive at the ear in succession. With delays greater than 5 milliseconds with simple sounds (clicks) the ear perceives distinct sounds. With more complex sounds the time increases to 40 milliseconds. The emission points of the mddOmni acoustic load are located at increasing distances from the driver and the sound fronts have delays between 1 and 10 milliseconds. The succession of sound fronts prevents the activation of the Haas effect, an event cannot be perceived as two distinct sounds.

Using MDD technology is equivalent to covering the reflective walls with diffraction panels, the possible paths of acoustic energy between the speaker and the listening point are multiplied. MDD technology can also be used in highly reflective listening environments. The delays optimize listening in environments that are not acoustically treated, it is the same effect that is obtained by applying passive diffractors to the walls. The waveguides generate delays between 0 and 10 milliseconds, the emission envelope expands (lasts longer at the listening point) and the reflections are perceived as generated from the same origin, listening fatigue decreases and recognizing sounds is easier. The omnidirectional emission with the multiplication of the possible paths further reduces the possibility of activation of the precedence effect.

frequency domain​

The 1a-direct prototype increases the level of high frequencies at the listening point. In the MDD3ZC350 V2 prototype the high frequency sound energy is emitted by the 3FE25 driver in a frontal lobe, the mddOmni acoustic load redistributes it over 360 degrees, reducing the sound pressure. With the 1a-direct prototype, high frequencies can be heard well even at reduced sound levels compared to the MDD3ZC350 V2 prototype alone.

The MDD3ZC350 V2 prototype reproduces low frequencies below 100 Hz better than the 1a-direct prototype. Neutral cabinet technology is used in both prototypes.



the mddOmni frontal acoustic load of the MDD3ZC350 V2 prototype is made with 5 rectangular cardboard waveguides of increasing length, the series has Lmax = 8Lmin = 2000 mm, (379, 574, 871, 1320, 2000 mm). The 5 guides are arranged in a cross and create four additional open 90 degree waveguides outside them. The emission of each waveguide is omnidirectional even at high frequencies due to the phenomenon of acoustic diffraction.



In the MDD3ZC350 V2 prototype the rear acoustic load mddTL is made with 7 waveguides of increasing length, the series has Lmax = 2Lmin = 3400 mm (1877, 2072, 2288, 2526, 2789, 3079, 3400 mm). The guides function as multiple transmission lines and have the first L/4 resonance frequencies homogeneously distributed between 25 and 45 Hz. The internal volume of the compression chamber also activates the resonances of the waveguides open on both sides, the first L/2 resonance frequencies are distributed homogeneously between 50 and 90 Hz. The frequency responses of the waveguides overlap in such a way that the acoustic energy of all frequencies above 25 Hz can be transferred into effectively from the compression chamber to the listening environment. The mddTL rear acoustic load attenuates the emission at high frequencies.

In the 1a-direct prototype the mddTL rear acoustic load characteristics are similar to those of a transmission line approximately one meter long. In this case I used 9 5 mm honeycomb polypropylene panels glued with a 10 x 10 mm aluminum profile inside fixed to the wooden base of the MDD3ZC350 V2 prototype. The panel sizes are: 445, 481, 519. 561, 606, 654, 706, 763, 824, 890 mm. In total there are approximately 180 waveguides of different lengths with their respective resonances compensating each other.

Each waveguide has its own frequency response with more resonances than the air inside it, the frequencies change with length. Listening is not penalized by this effect as hearing has a logarithmic sensitivity to acoustic pressure and the individual emissions add up with the properties of logarithms. If the resonances are distributed, spaced and overlapped appropriately, the overall frequency response will be regular. The logarithmic sum of the sound pressures is also useful for mutually compensating two speakers with different frequency responses. Listening to the CL08A2 prototype you can perceive a better frequency response compared to the individual 1a-direct and MDD3ZC350 V2 prototypes.

subsonic resonance support​

The subsonic resonance mount acoustically isolates the speaker from the floor in the audio band, avoiding unwanted interactions between the floor and the speaker. The video shows how the CL08A2 prototype oscillates, the frequency is so low that the oscillations can be counted directly.


The base is a plywood square 20 x 340 x 340 mm. It has three rubber feet mounted asymmetrically, two on the front edges and one on the rear side at 210 and 130 mm from the edges. The L-bracket of the subsonic support of the MDD3ZC350 V2 prototype is attached above the rear foot. The L-bracket of the subsonic support of the 1a-direct prototype is fixed above a front foot.

wiring​

The project uses the 1a-direct and MDD3ZC350 V2 prototypes, each channel has two 3FE25 drivers from Faital-Pro connected in series.


The series connection circulates the same current in the 3FE25 drivers of the same channel. The forces applied to the speaker cones are proportional to the electrical current flowing through the coils, so the drivers will be perfectly synchronized.

With a parallel connection the amplifier can only control the voltage applied to the loop. Due to voltage-current phase shifts, electric currents could be generated in the mesh itself which are not compensated by the amplifier.



The cabling uses cat5 UTP cable in star-quad configuration. The positive pole uses wires: white-orange, orange, white-brown, brown. The negative pole uses wires: white-blue, blue, white-green, green. The connections are soldered directly onto the driver poles. The negative pole passes inside the basket to prevent the ferromagnetic material beam from activating hysteresis phenomena which increase distortion.

Link:
MDD Multi Delays Diffraction

mddOmni
3D effect
anti Haas effect
omnidirectional acoustic diffractor
psychoacoustics

mddTL
neutral cabinet
logarithmic sum

subsonic resonance support
asymmetric base

CL08A2

Anybody have one? A great value?

NOS in the box aerogel Audax midwoofer -$49 . I have only this single one and post the picture soon.

Posting here to avoid Ebay if it can be done. USA only since it makes no sense to source it from abroad

I have another problem NAD. I purchased this knowing it was needing repair. When I opened it up it smelled like it was in a house fire. I cleaned it up and it looks like it was never touched. So, I plugged it into my DBT and Vairac and was pleased to see no smoke or bright bulb. Now is where the fun begins. I decided to test it and low and behold it was fine. I ran load test with 4 and 8 ohm loads. Distortion was fine. Output was great. Perfect. Then I decided to recap it and put new relays in it. Now it stays in protect. I used all good new tested caps. I know the old adage of if it not broke don't fix it but if you saw the physical condition and smell of this thing you might of just used it for parts. This is frustrating because I'm not an electronic engineer but I have experience with this hobby for years. Any ideas?

I have an old Exposure X over here. It needs some service.
But i can see that the Alps is replaced at some time. Also an emitter resistor (with a wrong value).
The Alps that is now in the amp has 100k impedance.
Does anybody know if this is the right one. I see different values on the internet.

Hi. Has anyone got a built crossover for lxmini speakers that they don’t need any more?

I would be very grateful

Thank you, David

So I've got an issue that I've never seen before, and I'm confused. On one amp, if I measure the voltage on the plate of the driver tube (6350) I get around 350v which seems to be fine, but when I measure in the same place on the other amplifier, the voltage shoots up over 500v.

Does anyone have any idea what would cause voltage to end up so high here? At the bottom is where the mains trafo goes into the diode bridge, goes through a 5k resistor, and then into a 68k resistor before it's on the plate of the 6350.

I'm starting to question my sanity with this amplifier, if it didn't weigh 80 lbs I might throw it in the street.

While rebuilding my Apt Holman, I kept looking at the empty MC expansion header, thinking it's a shame to let it go unused, and wondered if something could be done about it. With some careful measurement of the insides & close exam of the schematics, it seemed feasible, so I decided to try building a board for it.

Having never seen an actual factory MC card (real or photos), or schematic of one, or know anyone who has one in their Apt, I didn't know how they'd built or fitted it, so had to wing it somewhat.

The goal was to build something simple & small enough to fit within the Apt confines, using quality, proven components, with performance worthy of the Apt.

It's based on the AD797 opamp, as these have been used in other MC head-amps with good results and performance, and are easier than discrete transistors for non-EEs (like me) to work with.

With the sage advice of real-life engineers, the schematic and PCB layout were drawn, and the boards fabricated and populated. Made a couple of mistakes on the physical board layout, but not the circuit, so was able to work around them.

The Apt expansion header only includes +18v, so had to bring in -18v by a separate wire tapped into the main board. Kind of a kludge, not plug-n-play, but it works.

It fits good and sounds great, so the main goal was accomplished. Concept proven, I've started working on a newer design that won't need to tap into -18v (and w/out the mistakes!).

Hello everyone!

I had this idea for a while, but only now had time to come up with a rough draft of the schematics.

Board has a simple functionality that will allow the user to power on/off various devices by a simple push of the button.
When the device is on, LED is lit to indicate operation.
1W SMPS is used to energize the NE555 circuit that monitors the user input.
When the user pushes the button, relay connects mains live.
When the user pushes the button second time, relay disconnects main live and LED is turned off.
Mains neutral is passed through at all times.

Please feel free to point out any obvious flaws.

Appreciate everyone's help!

HI Guys,

I was desoldering some electrolytic capacitors from an old AV for salvage today when I encountered one that just wanted to accumulate a voltage.
I was working away when I suddently had a spark when I shorted the -ve rail and ground.
5000uF/71V and the thing just wanted to build it up.
After the spark is had -20vdc on it.

I used a 2k resistor to de-energise the thing. Desoldered it and measured it again.
With it connected to my DMM and nothing else, I watched accumulate voltage at something like 100mV per second.

This doesnt strike me as normal behaviour.
Does anybody know what is going on here?

I am aware things like CRTs can accumulate voltages by themselves but I've never seen it in a capacitor before.

Hello,

I was thinking of getting the ICE Power 700AS1 https://shop.icepoweraudio.com/product/700as1/ as this comes with the power supply, but I'm not sure that can even do it. They quote 700W into 4 Ohms, 350W into 8 Ohms, or the 1200AS1, https://shop.icepoweraudio.com/product/1200as1 is probably a better fit, 1200W into 4 Ohms, 600W into 8Ohms.

These are getting quite expensive, so wondering if you know any alternatives? A bare PCB is fine, but I also need a power supply, either integrated or separate.

A bit about the application, I am building and testing core saturation and temperature rise in an inductor.

These are Long-life grade capacitors made by Epcos (now TDK) in 2017.

Made in Hungary. New old stock, never used.

All items are tested by Capacitance, Quality factor (and ESR) measurement.

Specification:

• Rated voltage: 500 V
• Surge voltage: 550 V
• Rated capacitance: 3900 uF
• Tolerance: +/-20 %
• Maximum operating temperature: 85 °C
• Useful life at 85 °C: 12 000 h
• Maximum current at 40°C, 100 Hz: 38 A
• Maximum current at 85°C, 100 Hz: 14 A
• ESR (max): 42 mΩ

Tested electrical parameters:

• Capacitance: 3,25 mF
• ESR: 23 mΩ (@ 120 Hz)
• Quality factor at 120 Hz: 18

Measured ESR is half of the specified max, therefore the product is in new condition, but please note that capacitance is -16...-17 % lower then the nominal (within +/-20 % tolerance). This is normal.

Applications:

• Frequency converters
• Uninterruptible power supplies
• For switch-mode power supplies in professional equipments
• Audio applications

Mechanical properties:

• Diameter: 77 mm
• Body height: 145 mm
• Total height: 176 mm.
• Mounting: M12 screw
• Termination: M6 screw
• Mass: 850 g

Price:
1 piece: 20 EUR
2 pcs: 16 EUR
3 pcs: 14 EUR
4 and over: 13 EUR

Shipping:
I can ship only to these European countries (with DPD, unless you can advice an other reasonably priced delivery company available in Hungary):

Open box , maybe 50 hours of use , silver. Got it in exchange for something I don't remember anymore. Warmish sound signature ,hefty transformer inside and class D power stage . Well regarded little lifestyle amp. Kept it to pair with Nagra pre which was relegated to a display role since. Box and everything included, pictures follow . $200

Hello to all members of this forum. I wanted to ask for help in building a simple tube tester based on Arduino like this one: http://agalavotti.altervista.org/TubeTester1/TubeTester1.html I made a test assembly and had the following problems. I only have the correct reading of Vg (input -8.3v, reading -8.3v), Va (input +200v, reading +9.34v), Vf (input +12v, reading +0.53v), they are well below the input value. As for Ia, I wanted to ask for help on how to connect the A2 port of the ADS1115 to the analog part of the circuit. My goal is to test normal tubes ECC81, 82, 85, 88, EL84, EL34, etc. Thanks to anyone who can help.
Thank you, Fernando

Hello,

I am seaching for a replacement transformer for my Boston Acoustics Micro 90PV sub.

Can anybody point me in the right direction where i can order it? Prefferd in the EU.

Kind regards.

Hello friends, I can't find the answer to the question I mentioned in the title. I have capacitors with different different uF values. I have to choose a capacitor to use in my tweeters. Is there a table or site with frequency according to uF value?

Hello!
Who has the crossover circuit of Tannoy V8 and i8 for sharing?

Many thanks!

Well... 🙂

Preferable from € land...

Only the amp modules. No pow, no box.... no etc...

//

hi, what could I replace a 904A184 tweeter with?

Hello everyone!
Whith BMS should i choose or your recomend for LiFePo4 batteries 24V-320Ah?
LiFePo4 batteries for 8pcs 3.2V-320Ah.
Thanks,

Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD

**Updated: Lower distortion with a slightly different board.
**Updated 2: Distortion is even lower than before, found a piece of steel was interfering with previous measurements. (thought it was tinned copper)

Alright everyone! We’ve got the redesign done.


(Image of prototype)

The EC7293 uses 2 chip amps in parallel for high power with a discrete error correction frontend which reduces distortion; and has very low memory distortion. High sensitivity makes it perfect for a variety of sources with 8ohm and 4ohm speakers.

Input impedance: 27k
Gain: 32db
Distortion 1K; 8ohm; full power w/Antek AS-3225: <0.0005% (immeasurable by us)

No Load

8ohm

4ohm

2ohm

Loopback




Board size: 6.25x2.25"

*****There is not a mirrored left/right set because it would screw up the feedback layout*****

Discrete front end: 4 transistors

PVI: The frontend uses a photovoltaic power supply for galvanic isolation of the signal path. It uses a G4 LED bulb with a current source to disable the onboard driver of the G4.

Distortion: <0.0005%

High power: These are running in "modular" mode so that they can handle a 4 ohm load with some dips, while providing substantial power with a max output current of 20A. The Antek AS-3225 is a great fit for 60/120w. More power may be possible if you follow the guidelines of the TDA7293 datasheet and make provisions with higher voltage capacitors, and larger heatsinks.

Terminals: Happy to say we've found some that are based on a copper metallurgy, that accept decent sized wire, and don't strip too easily (I can torque them pretty good with screwdriver) that the boards are made to fit, and I recommend in the BOM.

Input Capacitor: This one is less sensitive to capacitors compared to the DIY7297. It has provisions for the same PHE426 and other caps. There is a slot-hole next to the pads so you can zip tie on larger caps and it has extra pads on the bottom to connect off board/long input capacitors.

CFC, smart PCB layout, & Copper Pours: Trace routing is optimized to improve performance and the power capacitors are placed for field cancellation (CFC); and copper pours are used for lower inductance.




Dualpole PSU PCB

Board Size: 4.25x3"

TO220 Diodes

CFC, smart PCB layout, & Copper Pours

Via holes for snap caps

RC and bypass: dampen the transformer & reduce noise


Suggested implementation with EC7293:

• 18000uF to 24000uF per rail
• Antek AS-3225 transformer
• Keratherm insulators from DIYAudio store. (Chip tabs are 1.1” apart).
• Heatsinks need to be larger than used on the 7297, nearly any enclosure with heatsinks for sides should work
• 3U enclosure from DIYAudio store is a good fit. **
• 2x Duapole's for dual mono with 2x transformers (Antek AS-2225)

**2U may work in dual mono with two smaller (shorter) transformers

Price & Amount needed to Print:

In order to print these up so I don't run out the day after, I need a commitment of 12x, two EC7293 boards and one PSU board. I'm hoping to see a lot more than 12x. To anyone that liked the DIY7297, this one is better, simply better.

EC7293+G4LEDR PCB $45ea (you'll need 2, to make a stereo amp)
DualPole PSU PCB $40ea

Shipping USA $8
Shipping International $16

And it will come with a BOM and some build details.

Paul Hirst 2,1 (1x)
s610adam 2,2 (1x)
Pi DE 2,1 (1x)
Roundtoit 2,1 (1x)
pistollero 2,2 (1x)
jmc207 2,1 (1x)
Danny23 2,2 (1x)
Domino99 2,1 (1x)
annamarykahn 2,1 (1x)

Click to expand...

I wrote this here but probably it was the wrong place. I think it's better to open a discussion.

I have an audiosector premium kit based on the LM3875 (Audiosector by Peter Daniel). The input impedance is set by R2=22K. I need an higher Zin because my tube premp likes higher Z. Have somebody tried an higher R2 value (like 50K-75K)?

Hello all,

I have this LM3886 based amplifier board. I want to use a small passive mixer as a source for it. The thing is, the passive mixer has something like a 2KOhm output impedance, which is kind of high. So, thinking that I need at least 20KOhm input impedance at the amplifier input, I set out to find out what it actually is.

Checking the manufacturer's spec sheet did not mention input impedance. Upon inquiry, they mentioned that the amplifier has a preamplifier stage, and that its input impedance is 2.2KOhms.

Upon seeing this quite low number, I thought it was possible they didn't have a clue what they were talking about. So I set out to try to estimate it myself. I used the following video:

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The trick is adjusting an external trim pot until the output amplitude is halved, then you can disconnect and measure your input resistance at the trim pot. The only thing I did differently was instead of using an oscilloscope to check output amplitude, I used a normal multimeter to measure AC rms voltage since I reckoned it's proportional to amplitude thus an equivalent measurement.

I used two test signals, one at 1KHz and one at 600Hz, of the same amplitude. Interestingly enough, my measurements for impedance with this method were 2.6KOhm @1KHz and 2.84KOhm @600Hz. The trick seems to at least yield higher impedance for lower frequencies and for certain the numbers are of the same order of magnitude as what the manufacturer claimed.

Now, supposing we have a source of about 2KHz output impedance, and an amplifier of about the same input impedance, what could I do to connect them without losing signal quality? I understand input impedance should be one order of magnitude higher.

I have attached a couple of pictures of the amplifier board and its input stage. Near the input I believe we see the op amps for preamplification the manufacturer mentioned. I wonder, could one solution be tapping the circuit after the preamplification stage where it could hopefully have higher impedance?

A final note, this thing sounds fantastic but I always found it too damn loud. I have to lower the volume a lot on all of my sources for normal listening levels. This is why I suspect that bypassing the preamplifier could be the way to go.

Any info/ideas/suggestions are welcome. Thank you guys.

Four used in good condition, 4 ohm,
send an offer, not sure what to ask for them

I got over 20 feedbacks on headfi in case you need proof im trustworthy 🙂

Hello all. I seem to have replaced all the speakers in my various listening situations to FR driver based systems. One difficulty has been finding powerful drivers for situations that need it. Looking into coaxial brings up threads listing the negative issues with existing units, as well as some threads on DIY stuff. MEH has been pointed out as one path, but it does take up some horn space

Would like to propose a community developed DIY driver that can be assembled at home from a combination of off the shelf parts and homemade bespoke parts. I have a number of ideas and thoughts on this and, judging by past threads, so do many others. We have already encountered the issues suffered by these drivers in those threads, so time to move on to exploring practical DIY solutions

I also propose that such a project should be economically biased towards the DIYer as well be solid and sound in performance and reliability. Ability to be hung of 100wrms and a native flat response would be good targets to aspire to, and the dynamic range to run some favourite Eq curves. These requirements would likely result in a driver not suited to very small amps so let's acknowledge that here

Point source fans would also be aware of the design of most of the drivers raised in the previous coax threads, so let's first round up some more units that try to make an attempt at cleaning up the HF

Here is a new one for me. What looks like a whizzer is not part of the woofer section. It doesn't move and forms a guide for the tweeter. I am aware of those older type large woofers with rectangular horn over the coax tweeters. This driver seems to differ a bit by trying to balance woofer cone depth and guide height by taking a flatter approach. Could this be the approach to explore for the community development? I want to investigate this approach in detail by combining an extended range subwoofer/woofer and a FR or tweeter that can go low. The donor woofer would have a large enough dust cap that can be removed to mount a custom throat that can retain the higher frequency driver and the woofer vent large enough to run a line to a volume mounted behind the woofer magnet. If we can find the right donor woofer and HF driver, then we can place a custom foam overlay on the woofer cone to change its dish to a flatter one while matching a waveguide to the HF unit that will ensure zero interference with the woofer cone surface. I have a feeling this can work with enough development effort. The overlay can be made easily with DIY jigs, and I am able to demonstrate that. At some point I will attach some FreeCAD files that we can pull and tweak for the guide and HF throat, line and volume and this can be printed at home

For anyone thinking of IP type issues here, let's be fair, if anyone can take any ideas from the thread and commercialise it, well make it good enough to be worth my while and I will buy them from you!

Hi everyone,

I have a 'Monster Power HDP1750G+ Powercenter' power conditioner which is making a loud buzzing noise.

The unit seems to be working fine other than the buzzing noise.

When you plug it in there is no noise. You turn the power switch on, and there is a low volume buzzing noise from the left hand side of the unit. Then after about 10 seconds a relay kicks in and a loud buzzing noise comes from the right hand side of the unit.

I have contacted Monster and they have told me that this noise is the surge protection circuitry kicking in and that I should dispose of the unit.
They have also advise there are no schematics available for this unit.

I have opened the unit up and everything looks clean and healthy (nothing looks blown or damaged).

The buzzing seems to be coming from the section with the varistors, chokes, caps, and relays (circled in the picture)

Has anyone come across this problem with a Monster power condition before?

I am suspecting it's the varistors which is making the noise and needs changing? Am I correct in my assumption?
If so, is it something I should do? Or is it time to dispose of the unit?

Thanks

Objective: I am looking to a) measure the components on the 2-way crossover of the Tangent Acoustic RS2 speakers I have and b) duplicate the crossover to build a new speaker with the same drivers (T27/ Audax HD20 B25J).

Current Plan:

a) Map out the circuit with a continuity tester
b) Identify bands on resistors/markings on Caps for ratings
c) Use an LCR meter to measure and confirm labled vs actual
d) Establish the delta and list components that need to be replaced in the old crossover.
e) Purchase components to re-store old cross over + build a new crossover.
f) Learn how to solder 😀 and build it out.

Current Roadblock: Purchasing a LCR meter that allows me to measure all components. Hence this thread.

I am considering the Tenma 72-10465 and the EXTECH LCR200.

Reason: Budget, and I see the EXTECH supports 5 different test frequencies vs the 1 on the Tenma. I am hoping for accurate readings on the 3 inductors since they can be hard to measure (is my understanding)/can influence the sound heavily if not duplicated correctly.

Seeking feedback from folks and their experiences with rebuilding/duplicating a crossover. Thank you!

Hello
Looking to test drive a component..
Wondering if real world conditions for the THAT1253 device will work with my present power supply..
The device has a listed minimum VCC-VEE of 7V, and I have +-5 for 10V, and I am curious if this is an adequate margin.
Not in the mood to redesign my power supply if not needed.
Preceeding single ended signal voltage is 2.1Vrms and differential is 4.2Vrms from the DAC that I have.

Thanks for any advice
S