https://www.smithsonianmag.com/smar...n-likely-world-first-video-footage-180985847/

🤔😱

Hello everyone,
For the last 2 or 3 years I have been quietly reading everything I can find on this forum about the LM3886 chip amplifier. This is because I have been building a dual mono amp with this chip for many years. It started as a small project. I had a pair of speakers and no amplifier to drive them. Now I am far down the rabbit hole. I have tinkered with a point-to-point setup and designed a few PCBs.
The latest board I want to talk about in this forum. It suffers from oscillation when the output voltage reaches the rail voltage (and while clipping). Perhaps someone has some advice on how to fix this?! More about this later in the chip amp subforum ;-)
Regards
Sven

Hi,

This is my first post here...

I want to add a headphone jack to a vacuum tube pre-Amp I'm building. Nothing fancy, but low distortion, I'll design the PCB to fit my chassis space, so a schematic would be cool too. How is LM380, LM386, LM1875, TDA7265, etc...? What stereo chip Amp has low THD and a simple circuit that will fit on a 64x64 mm PCB (sans power supply) and makes a fine easy headphone amp? Driving phones is easy so power is not an issue, I can do L Pad attenuation and matching of the phones to an 8 ohm chip Amp.

I just have no experience with chip amps at all, so hoping for some guidance to fast-path a foolproof headphone jack here, looking for a good chip for this application. I was at the headphone Amp forum, but decided I don't want to spend the time on somebody's discreet Amp design which may need troubleshooting. So I thought a chip Amp would be better here, more turn-key.

Thanks!

Drivers:
ND25FA-4 1" Soft Dome Neodymium Tweeter 4Ohm 90dB fs=1350Hz
Crossover 3000Hz
SIG180-4 6-1/2" Signature Series Woofer 4Ohm 91dB fs=40.5Hz
Crossover 200Hz
RSS390HF-4 15" Reference HF Subwoofer 4Ohm 91.2dB fs=19.5Hz
Links:
https://www.daytonaudio.com/product/1196/nd25fa-4-1-soft-dome-neodymium-tweeter-4-ohm
https://www.daytonaudio.com/product/1916/sig180-4-6-5-signature-series-woofer-80w-driver-4-ohm
https://www.daytonaudio.com/product/126/rss390hf-4-15-reference-hf-subwoofer-4-ohm

Sealed Box Qtc=0.707 Qts=0.43 Vas=212liter
Vb=124liter
Fb=32Hz

SPL in VituixCAD:

How exactly is the EPDR calculated as a function of nominal impedance and phase angle as reported in Stereophile Measurements section? Is it amp class type dependent? Do you have any reference to the actual derivations? Thx

Hi. I still have some pair of Pearl 3 PCB (my own design), for sale.
This design had being checked, built and certified 100% working. Already sold a few to happy forum members.
Come with full docs, and it is compatible with the official built guide.

Feb 6th UPDATE: Received a new batch of Pearl 3 PCB, in black this time, still 2 pairs are available...

Send me an email if interested.
SB

My ancient Exact waveform generator died so I need to replace it. All I need is sine and square wave output, adjustable amplitude and frequency, don't need all of the bells and whistles the Exact had. I use it to trace faults in amps/receivers etc and also to calibrate the recording function cassette/reel to reel decks. This is really just a hobby so I don't need expensive pro level gear. Dual channel would be nice.
Any ideas?
Thanks

Here is Current drive amplifier board for sale. I am working with current drive amplifiers maybe 15 years now. I don’t use boards with analog input myself, but decided to make one as sometimes I meet people interested in such board. Actually it is more mixed mode amplifier. Has 3 modes. Voltage mode and two mixed modes. Mixed mode where at low frequencies around resonance output impedance of amplifier is low, and above that is high. It is nothing extraordinary board. Made to be not very expensive. Uses LM3886 in composite configuration.



Some other features:

Clip protection/prevention
Overcurrent protection
Overtemperature protection
Silent turn on, turn of feature
Designed for SMPS supply
Onboard analog prefilter
Balanced input
And yes all COG caps in signal path and other obvious design things for good performance.

More things mentioned in my page and user manual is there https://www.baffless.com/analog-amp

Selling for 250Eur assembled and tested board. Without shipping from EU. You need power supply and heatsink. Good to tryout current drive. Quite a lot of posts about current drive, but no boards for sale as far as I know. In case current drive doesn’t fit your system, you can use it as voltage amp.


Before asking questions here please read the manual first.
Regards, Rytis
Thanks 🙂

Hi everyone, just finished my JLH1969 headphone amp battery version. I found here some interesting DIY resources and shared work wanna join and discuss.

Cheers
John

Hi everyone,

I am planning on building WAW speakers and I am looking for some advice.

Goals & Context
Here is some of the things I'd like to do in no particular order:

• Keep the box relatively small (around 30L max)
• Around 30cm wide baffle max and around 20cm deep (shallow design)
• F3 of 30hz, up to 20khz
• Should work well pushed into corners
• Vented box for the sub for extra extension
• Closed box for the wideband (or better suggestions?)

On a more subjective angle (probably not so helpful, but still including it here). I guess I love a 'vintage' sound that's not boomy in the sense that romantic / coloration is not something that normally bothers me. I want to be able to dream away and drown in the music. Not to say that do not believe in measurements, it's just that a flat response curve is not a particular end goal for me. One of the reasons I wanted this system to have an active XO is to also learn and listen for myself how drivers can integrate to produce a sound I love.

Where I am so far
I've been both drawing up some sketches for aesthetics and playing around with Hornresp to get some feeling for what is possible. Nothing is decided yet but I am aiming for something like below. This particular one is sketched to be 294mm wide, 193mm deep and 770mm. I like this because in my opinion these look 'less heavy' when placed on a stand or legs (which I haven't designed yet), as opposed to a floor-standing tower that reaches all the way to the ground.



So far I've made these decisions:

• Wideband will be Markaudio MAOP-5s
• Subwoofer will be the SB23MFCL45-4
• I'll use a MiniDSP Flex as a digital XO
• Port on the back

There is still lots open. With this thread I am mostly looking for some thoughts and input for further exploration. Not sure how best to approach this, so I think I'll just post the things I am pondering over in separate posts for anyone to shoot at. Starting with...

A Hornresp Rocket?
In Hornresp I currently converged on modelling a vented box for the SB subwoofer with a slight taper, that gave me a response in the 30hz region while remaining the internal volume under 30 L. Here is a few screenshots from one of the configurations I ended up with, just to give you an idea of what I was doing:




Then I started playing around with this configuration and I suddenly ran into this weird configuration where the horn is almost like a rocket. This simulates really well for my purpose and decreased the size of the port somewhat. Not sure if this is something I will do, but I am honestly wondering how this configuration can give such a response? The start of the port feels so incredibly small... Anyone knows what is happening here and if this is something worth exploring further? Some screenshots...

Hello from Leipzig. I'm a big audio enthusiast and want to learn about speaker building and designing. I'm mostly interested in building a multiple entry horn, once my budget allows.

CHeers!

Hi Every one. Just shook life to the old Pioneer SX-750, bought some old Sonab 0A14 speakers. Match it with a Pioneer PL-112D turntable. Now I found this forum and are into build some speakers.
Cheers!
Erik

And thank you for letting me being a member of this exceptional forum. I'm Davide from Milano, Italy and as an introduction for my passion i can say that i have been always fascinated from stereo equipment and i remember very well all the afternoons spent in the electronic shops back when i was a child in the early '80s.
After a long time i opened a box full of old magazines and started to re-read all my stuff and i found all my notes with prices and impressions...
So i started again to buy some equipment and even if the rack is in costant change some pieces will stay, and in detail parts i have acquired and restored my myself such as 2 Scott tube amplifiers, a 222d and a 299d, a Scott 342b, JBL 96 in excellent shape, a Teac UD-301 usb D/A converter and some other stuff. I started to restore tapedeks since i want to refresh a Nakamichi 480 which i left sitting on a shelf for more than 20 years unused and an Onkyo TA2570 which has some motor troubles.
So thank you everyone and ... let's start!

Greetings from Cologne, Germany!
Really impressed by this community so far. I'm beginning to dive into the ESL-rabbithole, but my background in audio is quite limited, so I'm really only at the beginning of my journey with you guys!
Looking forward to it!

Hi, i'm from Brasil, and i'm new to the world of audio, i hope learn a lot with yours, and i'm enthusiastic to be here!
Cheers!

I just got done restoring my beloved Yamaha K1020 tape deck. I replaced all the rubber in the mechanism and pulled apart the capstan motor to replace a faulty speed control IC. I also re capped the entire power supply and preamp coupling stages using Panasonic EB in the PS and Nichicon Muse ES between audio stages. It was a struggle finding parts for the mechanism but now I can enjoy my favorite cassette deck again.

My question is, does modding a tape deck even make any sense these from a practical perspective? I can definitely hear a difference in character for the better, but its still not as dramatic as doing the same with a digital source component. What are you're thoughts?

Hi!

I recently built Rod Elliot's p88 preamplifier. https://sound-au.com/project88.htm
I love his designs and boards, the thing is, one of the channels of the preamp does not output the preamplified signal.
To troubleshoot this I injected a 1Khz sin signal in R In and L In

The following first gain stage works fine for both channels and I see the 1Khz sin signal both in AL and AR (measured with my oscilloscope).


The balance and volume controls also work great, and I get an adjustable 1Khz sin signal in BL or BR , depending on the channel where I inject the input signal:


The problem starts in the second stage. U2B (OPA2134) works great and I get the preamplified R Out signal, whose gain is adjustable by Gain R switches.

However, I can't get a preamplified signal out of U2A pin 1.


Pin 3 shows the input 1khz singal, pin 8 and 4 show +15v and -15v, but pin 2 and pin 1 read 0v, no signal present.
What could cause this? I checked the board and all components are placed in the right place. Can one of OPA2134's opamps be faulty, while the other is working fine?

Any ideas of how to further troubleshoot this, in circuit? I soldered U2 in place without a socket, and would love to hear some of your advice before desoldering and soldering a new one.

Your help is strongly appreciated!
Thank you so much!!
Fran

Part of my clear out...
3x clock boards, I think these are type 1 as I only ever toyed with TDA CDP's. These are standard XO's. One has been removed from an old cdp today but it was never used. $30 plus post for all 3.
Original product link. http://www.audio-gd.com/Pro/diy/JZ1/JZEN.htm

Hello, a 15 channel Vu meter with peak hold feature. The microcontroller outputs are powered by MOSFET to control LED diodes. You can also use COB LED modules or 12V lamps instead of LED strips. It is also possible to control a 220V lamp using the MOC3020 module and triac.

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CAUTION: If you are thinking of using a 220V lamp using a triac module, be very careful. There may be large explosions at high voltages, use a Fused Power Line and protective glasses before operating the circuit.

Finally putting some legs on my MiniDSP DDRC-88D active system.
When I do the reclocking - is it recommended to use one reclocker on the 88D input? Or am better served by having one on each of the four crossover outputs?

Or does the DDRC-88D do it for me? (though not mentioned in the literature from what I have seen)

Obviously, funding one reclocker is easier than funding four.

Thanks.

Hi I'm trying to restore my dad's CEC BD7000. It's already up and running and looking good.
But the tone arm is using a toothed belt to adjust the anti skating. These belts are known to detoriate over time.

These tone arms are the same as the Rega R200 tonearms, with the same anti skating problems. I've read several threads that replacing the belt, requiers removing the arm disconnecting the wires. I'm quite technical, but this way to small and fidgly for my.

Is there a workaround for making the anti skate work again? Maybe you can get access to the cog wheel?
Or make a diy AS mechanism?

I am sad and devastated to inform you of the passing of Bruno Plouvier

Hello! Wasn't sure where to drop this but I'm looking for a manual for my AKG K240 Sextett "Cardan" headphones and I'm drawing a blank everywhere except HiFi Engine which won't allow new registrations. I'm trying to find some replacement parts, and while a lot of the newer version parts will drop in as replacements, some of them have been altered (at least aesthetically) and I want to keep them as original as possible.

Does anyone know where I could find some part numbers (or have access to HiFi Engine to check)?

So far I've found the Mk II and the Studio manuals, but nothing for the original model (if it even had one).

Hello,
My vacuum tubes for sale can be seen in my instagram profile.
https://www.instagram.com/vacuum_tubeseller?igsh=MXBwZTFwbm1nYnVqdA==&utm_source=qr

I repair, or at least i try to repair good quality hifi.

some time ago a TAG Mclaren DPA32R pre-amp came across which didnt turn on anymore.
i checked the voltage rails, all fine.
i checked the caps.. also all still very good.
after lots of fiddling i saw that the CPU somehow acted weird.
it had its clock signal and i saw pins switching that go to the SRAM and Flash. but nothing was happening. no data to the display or other chips.
after changing the SRAM and CPU for some new old stock ones, it still didnt work either.

i suspected a corrupt flash and went on, its nothing i can fix without a dump of a working one.

today, another Mclaren, this time a AV32R SL came to me, same cpu, same sram, same flash. same symptoms
nothing works.

i tried for hours now to find the issue.
the SRAM doesnt even get a Chip enable signal
just the Flash, it gets a address and spits out data. but i suspect this data to be corrupt aswell.

maybe the device turned off while writing to it?
i noticed when poking a finger near the address lines sometimes leds turn on and relays click. but it seems random.


now i checked ebay for defective / sold Mclaren, there were quite a few the last months. its very unusual that they all fail now.
they are so rare and unknown, that no one ever made a dump of the flash chip which is unfortunate..
also there seem to be no schematics available anywhere....

did anyone ever worked on these before?
maybe im overlooking something.


i was so close just slapping another microcontroller in there (in the DPA ) as its just shift registers to control everything.
no easy task without a working unit to see how it works.

shame that they now all go to waste, there were built properly. they were top quality back then. well ... except the flash chip it seems
long time ago i worked on a AV32R DP which only needed new caps as it displayed "initializing..." on the display. i was hoping for a similiar issue on those...

We know that we don't want a "one-note bass", the low notes must accompany the melody, the "walking" of a doublebass in music of blues or jazz must be heard with many harmonics. And the high notes should remain in the air, like the ringing of a bell or the cymbal of a drum when struck. Which is not so easy to achieve...
I found this link to a state-of-the-art speaker with 81 neodymium magnets, it is a RE of "only" 10 inches that has a BL of 2.4 Tesla!
Therefore I deduce the importance of a high BL factor for a speaker to be considered high quality/development.
The minimum currents that circulate through the coil will have a correlation in the movement of the cone, which with a low BL would be lost. Is this correct to think ?

https://www.stereotimes.com/post/cube-audio-nenuphar-loudspeakers-by-mike-girardi/

I'm building a rack-mounted audio switcher and need some advice on grounding. The power supply will be on a dedicated PCB, providing 5V for the microcontroller, 12V for relays and LEDs, and ±15V for the audio op-amps.

Would it be best to keep the power ground and audio ground separate, connecting them with a 10nF capacitor? Or should I connect them directly without the capacitor? Another option would be to tie the power ground to the chassis, with the connection to the audio ground controlled via a ground lift switch.

Hi folks.

I'd like to build a universal power supply for our "usual suspects" class A power amps, bipolar 23 volts with 1.5-2A bias.
I'd like to go the CLC route, and for space saving, shared rails (so ~4A per rail).
I already have an 800VA Toroidy with two 18v secondaries, two Triad C-59U chokes (10 mH, .1 Ohm, 12.5A), and I have nice but gargantuan Rifa 33000µf/63V caps in abundance (more than what's fitting in an enclosure).

I think I have gathered some hints here and there for PSU builds, but I'm not very confident.
So summing up all answers here sounds necessary.

- Rectification
I'm considering MOSFET rectification, using Saligny power.
But for such a "vintage" style PS, is the cost over standard diode bridge with snubber circuit worth it (mains harmonic, duty put on first cap and transformer secondaries)?

- Capacitor selection
The first cap after rectification has to be low ESR, and high ripple current capacity.
How important it is in my situation?

-Capacitor placement
Considering the size of my Rifa, I was wondering if there's an interest to locate the two last cap inside the amp itself, so CL in one box, and C in the other one?
I can imgine the benefit of the last cap being close to the load, but what about the drawbacks?

- Connector
How woud you terminate the interconnects, Speakon? LEMO?

Hoping for some ideas on what can cause the bias transistor Q309 to fail open circuit after a few minutes. Before it fails it's possible to adjust bias and the bias current stays stable until it breaks. The position of VR301 is as to be expected and there are no smoke or visible signs of overload on the transistor.
Is there a typical reason for a transistor to fail as open or short, for example will a collector current overload typically short the transistor (melting the junction) and a base voltage overload leave it in an open state?

I have built an Elekit Tu-8600s and use it to drive a pair of Heresy IV. My setup is in my home office which has some furniture and is open on the far side (away from the speakers) towards the rest of the house. I listen on the chaise in the middle of the room so I used a UMIK pointed vertically to measure the room and got this curve:



Then had the House Curve iOS app build a 20 eq curve shown below:



The speakers are under the windows, about 4-6 " from the wall, angled towards the listener.

Then I uploaded the correction PEQ into Volumio with FusionDSP. The correction quiets down the sound and it feels less harsh but I wonder if I just hear what I wish to hear. I tried using REW on my laptop but frankly found it quite complicated; still managed to build a curve but cannot hear a difference between it and the automatic curve created by the iPhone app.

What does a "good" curve look like and is there any value in pushing this further? I am a satisficer and would be happy to call it good unless some easy additional optimization can be had. Thanks for any advice.

At the end of 2017,
I obviously wanted to know whether an LT1028 and an OP27 (or OP37) are suitable for an acceptable, simple and rebuildable EQ.
Probably the motivation was to build a circuit to determine whether it works or not, all the reasons against it are well known - that's why I called the test project "Ice Cold".

Some of my handwritten data:

Overdrive reserve 26dB
RIAA deviation less than +/- 0.1dB
SNR greater than 76dB
THD less than 0.07% (this seems too high to me, but I don't remember under which conditions this value was obtained and with which measuring equipment, sorry)
Gain(1kHz) 60dB

C2 was measured to be greater than 2% and C4 to be less than 1%, all resistors metal film 1%.

The sound was great, open and completely transparent, crisp! Obviously it works fine with a (so often maligned) LT1028.


Kind Regards,
HBt.

Hi All,

Following the astounding success of my first full range design, I want to go onto something a little more interesting. I am trying to get my head around the Voigt pipe design and have a few queries and parameters I am hoping to confirm which will hopefully be clarified by the below picture.

1) The total internal height from apex to floor (including port) should be 1/4 of the driver's F0, correct?

2) The driver should be mounted about 50-60% of the way down the front baffle (by baffle I mean the front panel not including the port - see picture)? Is there an accepted standard position?

3) The pipe volume should be equal to or larger than the driver VAS, correct? Does the pipe volume used for this calculation include section B or only section A? Is a volume larger than the VAS preferable and if so, how big is too big?

4) Is the portion of the wedge above the driver normally stuffed or just damped?

5) Is the portion of the wedge below the driver normally covered with damping material? Is it ever stuffed?

6) How large should the port/mouth/hole be?

I am trying to model this thing in hornresp which is my first real attempt to use the package. I figure the TL design section is probably the bit to use. Regarding this...

1) Is the overall length of the TL in hornresp equal to the height of the Voigt Pipe or only the length above the port?
2) is the mouth area of the second interval in hornresp equal to the port hole area or the area of the wedge at the top of the port?

Any other thoughts or suggestions?

Any advice is much appreciated.

Regards,

Greg

I didn't intend to work on this one for some time, but silicone oil leaked from the dampers during shipping; I had to tear it down to clean it off. It only made sense to go through it before putting it back together.

Dear all,
I'm looking for a pair of aluminum T brackets for the 2017 version of the sony diy vfet amplifier ( to be clear this version: https://www.diyaudio.com/community/threads/sony-vfet-illustrated-build-guide.302380/)
Many thanks

GaN is faster than Silicon ,
Even more efficient than GaAs used in Military AESA radar

Any good GaN transistor for Class A amplifier?

I am a long-time audio enthusiast and I am just finishing my first dedicated theater. The room turned out very well but I am still working on getting the LFE to my liking. Glad to be here!

Eric

Hi. I am looking to buy a kit either the Aleph JZM or the ACA Min Max soon. This would be my first amp build and I think I would prefer to do the ACA because it seems simpler as a first amp but my priority is to not just build one but to build one that’s good enough to go with my GR Research diy speakers I started building and can give me a high level of performance sonically. Basically I am asking which one will bring me closer to something like the j2 or f5 which I’ve never heard personally but heard a lot about how good they are

Hi... my Lynx PCIe card allows me to change its digital I/O from AES to SPDIF via a jumper on the circuit board. I have the Lynx digital I/O breakout cables but they terminate to 3-pin XLR. So, in order to connect the digital signal to my Topping DAC's RCA coax connection, I need to build a short length XLR to RCA adapter cable. Lynx offers one (see pic) but since I already have a Monoprice 75 ohm RCA coaxial cable I'm not using, I thought I'd splice it and connect the other end to a female XLR jack.

Could someone help me with wiring the XLR side of the cable? I've seen a few diagrams online but I'd like to get the information here.

Thanks

I have and old pair of prolinear stage 60 speakers.
They are magnificent now

I'm having the exact same issue as this thread: https://www.diyaudio.com/community/threads/golden-tube-audio-se-40-filament-supplies.340709/

I'm not seeing an outcome or the ability to DM J Bbeede to ask if he ever got 'er workin'.

excuse my ignorance of the system - but the thread is closed and I can't see how to DM the poster.

any help would be appreciated.

DEAN

When amplifier powers on I get +11v on the RCA shield which after about a second goes to -12v.I replace both op-amp because one had DC on most pins but no charge.

Any suggestions?

Looking for a beefy ~8x5in (+/- doesn't matter) black anodized heat sink with 3/8 or more thick base plate and any height above 2inches.
If you have such item, maybe unpaired and not suitable for building an amp enclosure, and are looking to get rid of it please PM me.



EDIT: just to clarify, this is the type of heatsink I am looking for:

Hey im johannes from germany im really new into the pa-Technik. And planing to build stuff on my own🙂
Im happy to Flunder this forum to learn about

I have been designing some subwoofer motors in FEMM and recently figured out how to use David Meeker's tutorials for blocked impedance and shorting rings in Mathematica and Matlab. I have a pretty good design close to where I want it and the BL²/re in the FEMM model is where I want it too.

But I'm stumped on how that would translate into a real world number assembled as a unit with the soft parts. Say I end up with a BL²/re in FEMM of 100, but I build that motor into a 15" with say a 350g mmd. Will that result in a lower BL²/re than the model? If so, is there any way to correlate/quantify mmd or sd for its affect on BL²/re? Should I overshoot the BL²/re in the FEMM model to get the real world number I want?

What would like to see added or expanded?

For those who aren't forum members (or anyone who would prefer) email me.
babin_perry@yahoo.com

Hi all,

I have been using ChatGPT to help design a 3 way speaker for a 4w EL84SE amp and a 6w EL34SE Amp.

I have used it to analyse and review various speakers and I am narrowing it down to the following

Woofer: Faital Pro 8PR200 8" 200W 8 Ohm

Technical specifications

• Nominal Diameter: 200 mm (8in)
• Overall Diameter: 223.75/207.9 mm (8.81/8.18in)
• Bolt Circle Diameter: 210 mm (8.27in)
• Baffle Cutout Diameter: 183 mm (7.20in)
• Overall Depth: 116.7 mm (4.59in)
• Flange/Gasket Thickness: 10.7 mm (0.42in)
• Impedance: 8 ohm
• Minimum Impedance: 6.4 ohm
• AES Power: 200 W
• Program Power: 400 W
• Sensitivity: 95 dB
• Frequency Range: 70:5000 Hz
• Voice Coil Diameter: 52 mm (2in)
• Voice Coil Material: Al
• Voice Coil Former: Glass Fiber
• Voice Coil Depth: 19.3 mm (0.76in)
• Magnetic Gap Depth: 9 mm (0.35in)
• Surround Type: Triple
• Spider Profile: 1x variable height waves
• Chassis Material: Aluminum
• Magnet Material: Neodymium Ring
• Demodulating Ring: Aluminum Ring
• Flux Density: 1.15 T
• Driver Displacement Volume: 1 L (0.035ft^3)

Thiele and small parameters

• Resonance (Fs) - 58 Hz
• DC Resistance (Re) - 5.1 Ohm
• Electrical Q (Qes) - 0.38
• Mechanical Q (Qms) - 9.4
• Total Q (Qts) - 0.37
• Compliance Equivalent Volume (Vas) - 16.9 L
• Diaphragm Area (Sd) - 209 cm<small>2</small>
• Maximum Linear Excursion (Xmax) - 8.15 mm
• Maximum Mechanical Excursion (Xdamage) - 13.5 mm
• Moving Mass - System (Mms) - 27.2 g
• Force Factor (BL) - 11.5 Tm
• Voice Coil Inductance (Le) - 0.55 mH
• Moving Mass - Diaphragm (Mmd) - 23.8 g
• Compliance (Cms) - 0.28 mm/N
• Mechanical Resistance (Rms) - 1.1 Kg/s
• Reference Efficiency (Eta Zero) - 0.84 %
• Efficiency Bandwidth Product (EBP) - 153

There is a spec sheet with graphs here
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=101030200

Midwoofer : 6.5” B&C 6MD38

Specifications​

Nominal Diameter 170 mm (6.5 in)
Nominal Impedance 8 Ω
Minimum Impedance 6.5 Ω
Nominal Power Handling 120 W
Continuous Power Handling 240 W
Sensitivity 96 dB
Frequency Range 130 Hz - 6000 Hz
Voice Coil Diameter 38 mm (1.5 in)
Winding Material Aluminium
Former Material Glass Fibre
Winding Depth 9 mm (0.35 in)
Magnetic Gap Depth 6 mm (0.25 in)
Flux Density 1.4 T
Woofer Cone Treatment None

Parameters​

Fs 130 Hz​

Re 5.7 Ω
Qes 0.49
Qms 3.7
Qts 0.44
Vas 3 dm³ (0.1 ft³)
Sd 132 cm² (20.5 sq²)
η0 1.4 %
Xmax 2 mm
Xvar 4.5 mm
Mms 12 g
Bl 10.5 Tm
Le 0.25 mH
EBP 265 Hz

Design​

Surround Shape Triple Roll​

Cone Shape Exponential
Magnet Material Ferrite
Spider Single
Pole Design T-Pole
Woofer Cone Treatment None




https://www.bcspeakers.com/en/products/lf-driver/6.5/8/6MD38


They are both high sensitive designs and I would be grateful for any views and help on choosing a tweeter or AMT for a ported design and the size of the box.

Thanks

Hello everyone,
Does anyone have a service manual for a Sugden A25, Bias adjustment, offset, etc..
Thank you very much

Hi all, it has been a few years since I have spent much time at DIY audio forums. Now I think I need to build a new end of life time speaker. Or the last speaker I will ever need. I have been happy with the Watt/Puppy quazi clone that I made about 25 years ago. But now I'm in a slightly larger room and I want a lower bass response.

The design will be roughly similar to the Wilson Sophia. It will use a 10 or 12 inch subwoofer for the bass speaker. I don't have a large budget and I see that the price of raw drivers has greatly increased since I have built my last 3 way system.

I have pretty much decided on all of the drivers but the 8-9 inch mid bass. My Puppy clones used the VIFA P21W drivers which are very excellent sounding and very easy to get to work with a 12 db crossover. They were only about 60 bucks back then. The drivers will operate in an approximately 1 cubic foot aperiodic enclosure.

I have some new ideas to extend the quality of DIY MDF speaker cabinets that I would like to explore with this design. Inspired by the Rockport technologies speakers.

My budget is about 120-130 bucks each for these 8 inch drivers.

Here is a shape concept worked up for this speaker. I will go into the cabinet design later. But now I am seeking ideas for where to look for a great sounding easy to crossover driver for a reasonable cost.

Speakers I am planning to use:

Tweeter: Morel high end tweeter. these are never used tweeters I have had for some time. I forget the model number.
Upper mid bass: Audax hm170c
Lower mid bass: undecided 8-9 inch driver
Bass driver: Dayton RSS265HF-8 10" Reference HF Subwoofer 8 Ohm

electra print output transformers for 300b and alike
working great condition
4 8 16 ohms output
120ma
copper wire
asking $450 + shipping + fees
USA inland only

The powers that be would like for me to introduce myself, so here goes.

Over 30 years in hifi. Have sold equipment (hi end 2 channel) retail, have reviewed equipment for a handful of places. Back into "tinkering" since im now semi retired.

As requested a seperate thread on transformer based solid state amplifers.

The schematic:



... and what it looks like in practise ...



Everything to the right is power supply, and everything from the middle is amplifier.

See: http://www.susan-parker.co.uk/zeus.htm for more details.

This amplifier is based on Impedance Amplification and has similar distortion characteristics to valve triode designs.

It is relativly easy to build and only has one twiddle pot to set the bias level. The pic shows a monoblock which I built nearly ten years ago and it has not needed adjustment since.

Best wishes,
Susan.

P.S. Yes, it does work.

This is a group buy for parts to populate the CRCRC Power Supply that will ship with the Pearl 3 Kit from the DIYAudio.com store.

Group Buy Pricing for kits will be based on the volume of the group buy. It's looking like about $45 + shipping at a group buy of about 25 kits. There will likely be some savings at higher volume.

What’s included – everything you need to stuff the PCB including optional snubber caps and resistors:
Qty. = 1 - C1 - 3300pF, X1 Safety Rated
Qty. = 2 - C2-3 - FILM 10000pF / 10nF / .01uF - Snubber Cap
Qty. = 2 - C4-5 - FILM 150nF / .15uF - Snubber Cap
Qty. = 6 - C6-11 - 4,700 uF / 25V Nichicon or Illinois Cap
Qty. = 2 - R1-2 - 68R 1/4W Resistor - Snubber Resistor
Qty. = 2 - R3-4 - 3k 1W
Qty. = 4 - R5-8 - 4-10R 1W
Qty. = 3 - R9-11 - 10k 1/4W
Qty. = 3 - D1, 2, 6 - Diode Bridge - KBL Package
Qty. = 3 - D3-5 - LEDs
Qty. = 1 - TR1 - 15x2 V 15VA Transformer
Qty. = 1 - Terminal Block - Input - 2 Position Terminal Block
Qty. = 1 - Terminal Block - Output - 3 Position Terminal Block

The parts picture is from a Pearl 2 supply, so the values aren’t the same. It illustrates what you’ll get.

This kit will fit into the 1U chassis that is being offered by Modushop for the Pearl 3. It will also fit in a Hammond chassis. Both are tested and proven options.

Group Buy #1 COMPLETE
Group Buy #2 COMPLETE
Group Buy #3 COMPLETE

May 2024 Update - Appx 50 kits available - send me a PM.

Assuming parts cost is the same, the price shall be US$44/kit + shipping. Single kit shipping is $10 for USA, more outside USA.

Please make a running list by entering your DIYAudio username. I'll total things up when the group buy closes and order parts. Then I'll PM to finalize payment and shipping details. Payment via Paypal F&F.

Hi everyone,

Does anyone have a clue how to remove these bulbs?

24V/1,2W

Thank you. Jan.

Greetings all-
I've been lurking for a while and haven't posted here. I have two early Amber stereo 70s (black with rack mount handles) that are great. I'd like to use them in mono configuration with my Acoustat Spectra 44s, but one only works in stereo. From what I've read it could be as simple a fix as using deoxit on the stereo/ mono switch, which I'll do. The Spectra 44s are a difficult load and I don't want to stress the amps.

So...I'm looking for good LM391-100 or 391-90 drivers and an actual manual (Hifi Engine show that there is one, but it's not actually there). The schematic seems to be available. Does anyone out there have experience with Chinese made 391s? I'm a bit dubious.

Run as stereo amps, I prefer the 70s to my Eagle 2 and my BEL 1001 and they're basically equal to my buddy's Stax DA-80. Not too shabby.

Thanks-

Harry Z

Dear fellow DIYers,
I have purchased the Lampucera with Lampizator DAC kit from Lawrence in Hongkong for 220 Euros incl. shipping. I switched out one of the included transformers for a 50VA toroidal and inserted a OPA2134PA opamp (Second toroidal is coming for the tube output stage). Already I find this DAC very engaging and wins hands down against my Sabaj A10d AKM version with Topping P50 LPS.

As I have zero experience with tubes (never used them before), can anyone recommend a good 6922 tube for it? I was looking at this one:
https://www.audiophonics.fr/en/tube...-compatible-6dj8-ecc88-e88cc-7308-p-6162.html
Also opamp recommendations are very welcome.
Additionally I saw someone changing the output capacitors on the tube output stage for Jantzen Superior Z and was thinking of doing the same.

My questions are: does someone have experience with this particular kit? Can you share some of your thoughts and ideas?

Thank you very much!

​

Anyone have a simple schematic that can convert a single ended audio signal into a differential signal, but only using a single supply voltage (12V)?

Thanks.

There have been endless discussions about 2SK170BL replacement.
I have already published data indicating that 2x209GR in parallel would be a good replacement in all respects.
https://www.diyaudio.com/forums/pas...source-follower-applications.html#post5582425

Of course you can also use a single 2SK2145GR, which is in principle 2x 2SK209GR.
They are not guarantee to be a match pair, and from experience some 10% are poorly matched.
So the best is to measure the Idss of each JFET and select only the good ones.
But for those who just want to save money and don't care about performance,
no one will stop you from using the 2SK2145GR without any selection.

Here are the Gerber files of a small 5x5mm conversion PCB.
Both size and pin assignment correspond to the 2SK170BL.
Plenty avaiable at Mouser, etc.
What more do you want ....

🙂


Cheers,
Patrick

.

Hello,
welcome to my new tool for the Behringer DEQ-2496.
I love this gadget but turning knobs and pressing small buttons is not what I
like.
So I decided do create DEQ2496-Control because Simon Rhode (seoman)
stops his project DEQ2496-Remote. I've tested my Tool up to Windows 7 64
bits.
DEQ2496-Control is tailored to my personal needs. May be that I expand the
functionality in the future but everything I need is working.
You can use it free of charge. Use it on your own risks.


Please read the attached PDF before you use it.

DEQ2496Control-V099-Setup


Kind regards
BigD

My name is Nemanja, im from Serbia, my hobi is to make speaker and small amps, im newbie and i would like to learn more aboute lm3886 super gainclone with op amp...

Did anyone check out the recent article in Elektor Electronics? There's a class A/B amp, very low noise, discrete and through hole design.

https://www.elektormagazine.com/labs/fortissimo-100

To my eyes it looks kind of interesting. Symmetrical and pleasing to the eye. I can't judge the design, though, but interested if someone has any opinions about it.

The ThermalTrak transistors from On Semiconductor makes it a bit expensive to build and they seem hard to get right now, probably due to usual component shortages.

Greetings!
I am Valentin Derouet from France, passionate about HiFi and audio restoration. I manage dlr-audio.com (in construction), where I share tests, reviews, and repair guides for audio equipment, organized by brand.

Currently, I am exploring acoustic measurement projects, considering a B&K 2306 to draw sound curves from ARTA on paper. I seek to combine precision measurement with the art of sound restoration.
I'm building my own turntable for polar measure ments. (see https://www.diyaudio.com/community/...arta-stepper-motor-and-tic-controller.387325/)
I have all the Philips MFB in my collection plus a pair of Pioneer CS-E900.

Happy to exchange ideas and learn from this great community!
Valentin

Hello to all. I recently became a fan of NAD equipment. I accidentally stumbled upon their 50 years video and loved the story. So I immediately went on to Reverb and found a NAD 3020A in fantastic condition. I was not disappointed in the sound quality that this amp puts out. I also purchased a power amp (2150) and a 5240 CD player ( not that I will use it much because I am a Vinyl guy). I am looking forward to a great journey with you all in not only appreciating this equipment, but repairing as well. Thank you.

Hi everyone, I'm troubleshooting and repairing a Technics SL-1300mk2 that I have used for five years. It developed a speed issue. Not racing but just faster than 33 1/3. Cleaned speed switch, but the pitch control, which was intermittent before is not unresponsive. Anyone that can help me bypass the pitch control, get back to 33 1/3, etc. That's what Im here for, to learn about how to manage my own stuff. Thanks

Hi! I make loudspeakers as a hobby. I'm not bad at it. But I need some advice. That's why I'm here.

Hey all. I'm from the US and I am interested in learning more about DIY modifications to wired earbuds. I have a background in robotics/SDLC but have yet to dive into an audio project like this.

The specific mod I am looking to do is to take a pair of Apple Earpods USB-C and reterminate them with MMCX connectors. This would enable use of MMCX IEMs while retaining functionality of the existing Apple Earpods inline mic. The reason why I want to do this is because the inline mic on this Earpods cable is miles better than any alternative I've tried, yet I find the earbuds quite uncomfortable. I need a reliable solution for work calls, which entails me traveling a lot. I'm not a fan of wireless earbuds, overear headsets, or standalone mic type solutions. A service provider did this mod already but it's unclear if the microphone retains its function post-mod.

Any suggestions on where I could discuss feasibility/approach for this further in the forum?

Cheers!
James

Hello everyone! I'm a passionate music enthusiast currently working on repairing and upgrading some of my audio equipment, including a Pioneer DJM-600 mixer. I'm looking forward to exchanging ideas and learning from this knowledgeable community to enhance my HiFi experience. 🎵🔧

Hello everyone,

I'm writing to introduce myself as a hi-fi enthusiast from France. My passion lies particularly in audio electronics rather than speaker design and woodworking. I enjoy understanding, repairing, and sometimes modifying hi-fi equipment circuits to get the best out of them.

I look forward to exchanging with you all about our shared interests and learning from each other's experiences in the audio world.

See you around the forum!

Wild Burrow Betsy "L" Speaker Design

This is my design of a very successful Betsy open-baffle speaker design. I used Maple 3/4" plywood and cork backing. It sounds fantastic! don

Hi,
I'm new to this forum.
My name is Uli, I did an apprenticeship in 1986 as Radio-and TV-technician, studied afterwards precision engineering (Feinwerktechnik in German)
and work now for an international company which is leader in HVAC solution for cars as resident engineer at BMW in Munich.
I love repairing old audio equipment and building new ones myself, usually from schematics.
I create the associated PCBs with KiCAD (and previously also with Altium, until it became too expensive for me).
In vehicle measurement technology, I develop measurement equipment privately, sometimes also more complex measurement systems (mainly with ARM9).

At the moment I am restoring an old Thorens TD146, giving it a completely new wiring and installing a Denon DL103R.
I am also builing the phono preamplifier from “Bonsai” and hope to get a few tips and suggestions here.

Greetings form Freising
Uli

I'm wondering if anyone successfully crossed Dayton Audio RSS390HF-4 a bit higher, let's say at 400 Hz or so, to a smaller mid/extended range?

If someone did that or at least heard such beast, how did it sound?

Is it something one would want to attempt on purpose..?

Any experiences or opinions would be appreciated!

Hi Everyone!
My newest ESS DAC design is almost finished. I will make a group ordering action if there are any intrested guys in this forum...
Detailed informations are soon available, or please simply ask...!

I've rabbit-holed down a number of paths, and am now confused at a higher level.

My room is 12.5 ft across from where the sound system must go. 13 ft across, then one side opens up into a larger basement area. Mildly acoustic absorbing drop ceiling. Decent room, some acoustic treatment behind the speakers and bookshelves. Current system is a HTA100 hybrid driven by TV optical or bluetooth from other things (bluetooth's limits show up). The speakers are Polk RT55 Two 6.5" and a 1" dome tweeter. Well supported (invisibly) by a decent subwoofer. Not as crisp and detailed as I'd like for nicely recorded music, but nice for the TV.

I intend to find or build a reasonably compact pair of cabinets. These would move away for TV time, and for my relaxing time, move into the room a bit, would still be oddly placed (I think frugalhorn mk3 and other rear firing designs are out.

Small footprint, ideally no more than 3 ft / meter tall, more or less. I'd really like to be able to build with already dimensioned lumber, standard widths being 3.5", 4.5", 5.5", 7.25", 8.25" and so on. Sides I can use good ply.

I'm looking for clean, crisp, transparent sound. I don't need super highs or magic earthshattering bass. I just need moderate volume. I can rig to my sub, or get a small sub for each speaker if need be, but having them stand alone OK would be nice. Not so easily "seeing" where the speakers are would be great. My odd HiVi system is invisible, I can look right at the drivers and can't see/hear that the sound is coming from there. That's the sensation I want.

Decision 1: Size of drivers. I'm listening to 3" HiVi B3N in pipe TL at about 20" washing across computer monitor screen. That's what I want but large. 3" drivers may be too little. Based on reviews of various posts here, 4" or 5" seem right, given the size of the room. I could easily be wrong, and 3" might allow slightly more compact.

Decision 2: Which driver? I keep coming back to the Pluvia 7.2 HD based on "listening" to youtube videos. Other contenders include the Alpair 7 MS. But I really don't know. Something $75/driver is great, but I could go to perhaps $110 before flinching.

Decision 3: Cabinet. I'm tempted by the various tall open boxes, e.g., TABAQ and Pensil. But the folded up Voigt pipe versions (e.g., long Sibelius discussion) got me thinking. https://www.diyaudio.com/community/threads/markaudio-7ms-and-chp90-enclosure-options.402623/ has some compelling ideas. I really like the 12.5 ML design that heads that discussion, just conceptually. I may be nuts. Who knows, but that type of thing appeals. If I can pick a driver, and pull together a design that can use regular dimensioned lumber, then I can put together a nice solid-wood cabinet that would look good.

Odd question: Feasible, not bad, to put in a speaker selection switch box? My amplifier does not have a/b speaker select. I'd like to be able to use one amp to drive either set of speakers.

Thanks much for any suggestions and hints.

I have plans modify a pair of these including replacing the woofer with a different bass solution and then using an active DSP crossover for the bass / mid crossover at 180 hz, but leaving the mid / tweeter as passive.

I own a pair of the formidable Aurasound NS15 992-4A woofers and one option would be to put them in a sealed cabinet. However given the rest of the speaker is dipole, I’m wondering about putting them in an H or U frame. They have incredible Xmax and I could obviously EQ them with DSP. I also already own a very powerful amp to drive them. I’d welcome comments on these options.

The orignal circuit of st-70 has some drawback if you want to use it today. I did some mod to the original circuit to address those issues.
1. 16 Ohm speakers are not common nowadays. Changing nfb point to 8 Ohm tap makes more sense. As this change adds more gain after closing the feedback loop. The 390pf cap could be reduced as well.
2. 7199 tube is hard to find. The subtitude such as 6gh8 may have different bias point. Thus, I added DC negative feedback to lock in the bias point. The optimal voltage of the cathode of the triode portion of 7199 should be around 115v~125v. Here is a good writeout about this. https://www.angelfire.com/electronic/funwithtubes/pentode-triode.html
3. The shunt network (18K with 82pf) may not be necessary. I believe this portion is omitted in some of st-70 series II design. (Edited. I have played this for days with the oscilloscope. The amp is very stable without this network. There is a little overshot with sqarewave, but it is very stable. The original design is very aggressive. The amp has the gain-bandwidth product about 100KHz, which provides 20dB+ negative feedback at any frequency below 10KHz. It also reflects the engineer was very confident about its output transformer.)

I have a QED A240CD integrated amplifier that I’ve owned since new. I recently replaced all the electrolytic capacitors (except main filter caps) for quality ones and also the 911/912 and 140 transistors. Also replaced the Omron G2E-182P-M relay and the RS403L bridge rectifier. All this with the intention to check the bias settings to ensure all running nicely. DC offset on the left channel is fine but the right channel is returning 80mV when amp initially turned on (I’m aware this would change once amp warmed up). The heatsink does get quite warm (approaching hot but not so much that I can’t touch). Can anyone advise where my problem might be. Many Thanks, Andy

I picked up an Onkyo TX-SR607 AVR listed as faulty to see if I could get it to work. I’d like to use this as a low-investment opportunity to learn electronics repair. I know someone ‘tried to get it to work’ before I took it off them, and I’ve done a couple of things to it which in hindsight were misguided. The fault is that, when first turned on, after about 30 seconds it enters protection mode, and then enters protection mode after a couple of seconds thereafter. There was some water damage to the top of the case. The two resistors on the speaker output board for FL and FR shows signs of heat damage on the PCB, but measure fine. The output rails, +-B1, measure around 58V, not the 53.8V indicated on the schematic. I am in the UK and wonder if this is due to an assumption of 220V mains.

One of the channels (SR) has a few hundred millivolts on it when probing the central point of R6104 with no signal and no load. After testing all transistors and in-circuit resistances across all resistors and capacitors and comparing them to another channel I have not found anything which indicates why this would be. I suspect this is what is causing the amp to enter protection mode.

While 'playing' with this, I first shorted the output transistors on the SL channel (Q6053 & Q6063) while probing, unplugged but without discharging the capacitors, resulting in a bit of a bang and the transistors being shorted. I've replaced these with a pair from Aliexpress, I don't believe they are matched despite the listing, although think they are likely used genuine parts.

I also tried to remove (a few 10's of millivolts) offset from the FR channel's speaker terminals by adjusting the bios pot. Reading up on class AB amplifiers, this seems to have been misguided, given that it is setting the bias point, not modifying the position of the zero crossing! Anyway, while turning the pot to one end of travel one of the output transistors popped and burst into flames! The pair are currently removed from the board, and the rest of driver board is obviously not okay. Is this degree of destruction expected from enthusiastic pot usage, or was there likely a fault in the driver board already?

Many thanks for any help you can give me with this, it'd be nice to save this AVR from the scrap heap but appreciate this will be quite a learning curve for me.

Hello all,
Just got back into high end audio after a decades long hiatus and came here to poke around. Looking forward to learning and maybe getting some help.

Joe

Hello! I just got a Trace Elliot head second hand and when first plugging it in, everything seem to work fine (it goes loud and then some, built-in compressor is great etc.). However, I discovered quickly that the solid state to valve blend doesn't seem to work. When all the way to solid state the sound is loud and when turning towards valve it gets progressively quieter until there's no sound at all when it's all the way to valve.

I tried swapping out the tube with a known working tube but that changed nothing. I got it for a fairly good deal and the cost of repair quoted by a pro (£100) would be more than the cost of acquisition. It may still be worth it, but I wanted to check my option first... Is there a way for me to diagnostic the issue and see if it's worth fixing?

In addition, when I use pedals in between the bass and the amp, there's a loud pop when the effect is turned on or off. That doesn't happen with my other amp.

I found the repair manual online so I have the full schematic which is cool. I've got a multimeter and some basic tools and I'm willing to learn (if it's not too dangerous of course).

SY's newest baby in LA Volume 7.

I don't think that the 3.18uS compensation (Neumann) is necessary (the 91R):



Without it you'd be hard pressed to get an RIAA network which hugs the curves so tightly:



I can't wait to start soldering this one up!

I am designing a simple 14-15W unity gain power follower to drive my sealed box midbass system. To get good damping even below crossover I want it DC-coupled at the output.

I have never dealt with servos before, but have tried to come up with two versions by copying other. For some reason the left one sims slightly better.

The reason for the 10k resistor and 0.27u capacitor is to form a 1st order 60Hz HP filter. Removing C4 and C6 might be unnecessary, as they don´t seem to alter the sims.

Should the servo be designed otherwise?