There is/was a shop in Idaho that was doing upgrades to the DBX 3BX series one dynamic range expander. One of the things they did was swap out ICs for a much better OPA2134. It was a drop in replacement, no mods to the surrounding circuit needed. Other than that I can’t get any other information. This is what is in the unit:

10 - LF351N
8 - LF353N
10 - RC4558P
1 - LM301N
3 - unknown, the markings have been removed.

My best guess is the RC4558P. Could it be possible to replace the LF351N and LF353N with the OPA134 and OPA2134? I really wish I could get more info on this.

Is link a schematic, but the only one I can find isnt the best quality and needs to be zoomed in on. The images I post get fairly degraded.


Thank you,
Dan

found a pair of the Pioneer BOFU drivers in the office today. thought they were gone.

anyway, is anyone interested in buying these? the surrounds are good. they were installed in a pair of the hedlund cabinets & then returned to the original shipping box from parts-express.

$50 + shipping. probably via fedex or ups.

if any are interested, i'll post some pics.

thanks.

I've stumbled across a "grail" tube preamp for me for a decent price. However, it is about 20 years old. Should I re-cap it or, assuming everything functions properly, assume it's fine? I'm torn on this one ...

Hi all building my first ACA. I am following V 1.6 for the PCB and my kit didn't come with a 10K resistor for the R13 space on the PCB. I know the v1.8 has a diff wiring for the Chassis but not seeing what is supposed to go into R13 space. Anyone know what I am missing?

Thanks
jh

Does anyone have a photo or diagram of the 14-2Zx30001D-01 power supply board? Q2 is missing and q3 has been replaced.

I found this in some ElectroVoice product literature:

"When two speaker systems are placed side by side, the woofer cones “mutually couple,” causing the two systems to act as one system with twice the effective cone area at very-low frequencies, giving an additional 3-dB increase in maximum acoustic output. Mutual coupling will occur when the frequency is such that the center-to-center distance between the two woofer manifolds is less than about one-half wavelength."

I have two identical subwoofer cabinets, placed side by side in a corner of my listening room. They are crossed over actively at 90 Hz. I've been trying to get my head around the mutual coupling thing as it applies to these boxes. Here are the numbers:

Center-to-center distance = 44.7675 cm

Estimated Speed of Sound = 34500 cm per second

Frequency = Speed of Sound / Wavelength

For Wavelength = 89.535 cm, Frequency = 34500 / 89.535 = 385.3 Hz

What I get from this is that mutual coupling only occurs above 385.3 Hz. I wouldn't call these "very-low frequencies"! What am I missing here?

EDIT: I did a search here and now I'm even more confised....

I found this formula:

Fo = c/(d*sqrt👎)

Where

"c" is the speed of sound in the air in metres per second (normally 343 is used, but can vary slightly according to air temperature and humidity).

"d" is the distance in metres between the two speakers

"n" is the number of sources.

Fo = 343 / ( .447675 * 1.4142 ) = 541.77 Hz

Help?

Thanks,

dooper

I've have a Stryke Audio HE-15 in a 22" cube with two 18" PR's. My box (purchased pre-made) is roughly half of the box pictured (actual interior dimensions are around 22"x22"x22") in the following link - thanks "greg", it's hard to find these specs nowadays.

link for subwoofer

I have a Mackie m2600 to power it (I bought this used). Here is a link for the specs:

link for mackie

I have the Stryke's 3ohm dual voice coils wired in a series.

My problem with this is the output.

With the mackie in bridged mono mode, I do not think I am getting adequate output. The amp shows that it is giving it all she's got (the front led's light up to the "clip" level), but the sub is barely moving...maybe 3/4 inch excursion. And the sound level is certainly lower the my SA 12 in a 1ft^3 sealed box with a 500w digital amplifier.

The mackie has the low pass filters off and the crossover at 120hz.

What's going on here? I have access to a much smaller amp (around 150w) and I only have rudimentary tools (a Radioshack db meter and multi-meter).

Am I expecting to much?

If not, what steps should I take to test the driver, passive radiators, box design, and amplifier? - I'm gonna assume that the box design is OK at least.

Any help would be much appreciated!

Thank you,
Chris

i've been watching a few youtube videos (like probably most of you), which were actually non audio related and noticed how many people seem to be getting PCB's and custom chips made, which made me think of has anyone done a small bt amp for a lowfi build?

i've bought a few CSR8645 Amplifier Boards and other variants of them (QCC3008) and due to the size find it difficult to firstly solder onto, but trying to cram it, plus a battery and a boost coverter all into a tiny build.

So my question would be, has anyone done a custom build, if yes, would it be hard to do for somebody who doesnt know how (but keen to learn) and how hard would it be to integrate something like a TP4056/7 1S BMS and a boost coverter (3.7 to 5v) etc?

I have a few builds which are basically 3d printed 500ml beer cans with a downward firing 2inch full range and i want to use the amp as it has the ability to be modified through the BT chip and use custom EQ settings (and it is small).

example

Csr8635 dual 5w bluetooth 4.0 /4.1 amplifier board audio bluetooth 4.1 receiver module with call function Sale - Banggood.com

Just wondering if one can use one of those 1" thick styrofoam shipping boxes used to ship meat for a test box when calculating Vas or do you need a rigid wood or mdf box?

I have some mercury rectifiers that I have not planned on using. But I am tinkering with the idea of a 'show off' amp just for demonstrating the fascinating side of tubes, and tube glow is a part of that.

One set I thought of using is a pair of Philips DCG/1000-01. But I cannot find any data on filament voltage and current.

I do find the DCG4/1000, this has 2.5V/4.8A filaments. So can I assume DCG/1000-01 is 2.5V but only 1A?

Any one here know?

As for using mercury rectifiers. I know some of the risks, probably not all, I know one must apply heater power long before HT (at least 1 minute?). Is there a tell tale way of knowing when one of these are bad, and even if they may catastrophically self destruct?

If I want to dispose of them, where do I drop them off? I guess the local dump has 'dangerous goods' section and will send them to where they belong. I dont intend on selling them, just because I dont like poison going to who knows where...
Or am I over reacting?

thnx for comments

4 pieces of F2A tubes for sale $400usd OBO , one of the pair is used for a few tens of hours for an experiment. The other pair is plugged in for tests, and then stored. Selling as it is, no returns. Pm me to check shipping cost to your location. Will ship from Singapore.

This amp worked beautifully until I moved it and shoehorned it in a corner. Now it produces only a scratchy rendition at very low level sound. I opened it up and then realized I should stick to my day job.
Please help

Bit-Perfect playing WAVs - Advices for beginner

I'm just taking the first steps to get good stereo music from my WAVs through an entry-level system made up of a digital interface, a (digital) stereo amp and a pair of passive speakers running Windows 7 x64: no audio NAS, no media streaming, no music server intended.

I'm passionate and experienced about listening to music, both live and played within the walls of a room, but through my PC I have almost no experience at all and even if my PC-based system is currently an entry-level one I would like to (understand and to) get the max possible quality sound from, so I started reading and still reading articles and discussions, but now I'm a bit confused and would like to receive authoritative confirmations or even denials about some basic principles.

Running a capable software player is the Bit-Perfect playback applicable to WAV files?
If so, how do you get it?

I'm just trying 2 players that I like: Album Player (free) which I really like and JRiver Media Center (commercial) which I like enough, both with strengths and weaknesses and both with the ability to use the ASIO driver supplied with my audio interface.

I think I understand that if you use ASIO driver (or WASAPI too) for the Bit-Perfect playback then both Windows mixer and volume control are just bypassed and no longer functional, but I still can't get it: is the above true also playing WAV files?

Definitely, how to get theoretically and practically the best possible sound quality from my system playing WAV files under Windows 7?

Many thanks in advance for any appreciated addressing.

This amp works fine, but there is a hot spot on the amplifier PCB. The reason are two very hot transistors from front-end in a E-line envelope like this outline:
https://www.diodes.com/assets/Datasheets/ZTX652.pdf

For check the reason in detail I want to have a service manual or at least the schematic diagram.

Under
History | ONIX - Hi-End audio products from england since 1979
there isn't to find a download portal for pdf schematics and service manuals.

Who can upload the schematic?

More URLs:
https://www.audiovintage.fr/leforum/viewtopic.php?t=37135 (images)
Onix Audio - Wikipedia

Hey

Plan to build a old school large 2-way, perhaps petite Onken, or altec 612, or similar. Found a pair of Fostex H320 wooden horns (tips for a 1” cd going low would be nice, or if building an adapter to 1.4” is more clever, would probably work).

There are some old Emilar ew15-8a 15” woofers available, together with Emilar Ec175 and upgraded Emilar crossover of 800hz.

From some old threads, it sounds like the Emilar elements are compared favourably to Altec etc., but do any of you know? Or even have data for especially the woofers? (I read fs of 21 hz, likes large cabinets, was in a 220l box).
Maybe worth a gamble? Or better keep looking for a 414 / 416 / ? (Really hard in Sweden..)

Thanks in advance 😬

2 x 5 pair MJL4281A/4302A
Original ON Semi
Prefer one sale , 120 Euro free shipping for Europe buyers .

What would you do if you lived 3000+ years?

Read an interesting article: assume all medical issues are solvable and nobody dies of illness or old age problems. You keep the mind and body of, say, a 30yr old, indefinitely.
How long would you live then? The surprising answer came from life insurance actuarials: about 3000 years. That is the average life expectancy in our part of the world, based on only accidents, suicide, murders, that sort of thing.

Then I though: what would I do with so much time? Build your own home, a brick a day? Spend 30 years to learn all about amp design, design the ultimate one and build it including designing and building each part? Take up a study and spend 50 years to learn all there is to learn about, say, the Roman empire including doing an in-place decade of archeological digging?
Would you jump off the roof top due to sheer boredom after a couple of centuries?

The sky would be the limit!

Jan

I have a Halfler P230 amp. Even at very low volume, my speakers sound like they have bass breakup. I tried other speakers, and they do the same thing.
I checked the large power caps (10000uf 75 volts) with a VTOM. Infinite resistance. If indeed the caps are bad, would that cause this problem??? How doe the amp even work if these caps are bad?

I’m considering doing a build of Jeff Bagby’s Kairos 3-ways. I have built the CJD Khanspires, a Dayton RS series 3-way, and like them. I’m now interested in building something with a bit higher end drivers and a bit more exotic cabinet construction would be fun too. These will go in a 12x12 home office, so I don’t need huge output, but…

Has anyone built these, and if so what are your thoughts? Would you recommend an alternative for full-range, high quality sound smallish room?

hi do all Fosi amps cause loudspeaker pop?

I recently purchased a mint condition 1961 Empire 208 turntable. Everything was in excellent condition, sans the belt and rubber mounts. I replaced the belt and rubber mounts. I also re-lubed the motor thrust plate, turned the thrust plate over to the fresh side and inserted a new precision ceramic ball in the motor thrust plate. The platter spindle has a steel ball bearing which needs to be replaced, but I have not done so yet.

Using the iphone RPM app to record speed and wow/flutter (I can not vouche for the accuracy of the RPM app, but its the best I have), I recorded several measurements for speed accuracy and wow/flutter. FYI: I use a Long Dog Audio LDA Quartz Regenerator power supply which keeps a steady voltage. The Long Dog Audio unit allows the platter speed to be adjusted easily with 0.01 increments. So, I was able to lock into 33.33 RPMs and it did not fluctuate during use.

Using the stock platter (aluminum which rings like a church bell), the iphone RPM app recorded a wow & flutter measurement of 0.16 - 0.18%. This range was consistent across 3 measurements.

Then, I added a 60 pound platter from a prior DIY project to the top of the stock platter. The 60 pound platter was centered within 0.001" TIR. With the added mass, the wow & flutter measured 0.06 - 0.08% (again measured 3 times). The only variable between the measurements was the platter weight.

Also of note, with the stock platter and motor off, I spun the platter and it continues to spin for a few minutes. I used a stethoscope to listen for bearing noise. None detectable. In all my years of using a stethoscope, I always detected bearing noise until today. Quite a nice feat for a stock 1961 turntable.

Then, with the 60 pound platter added to the stock platter, I once again spun the platters and used the stethoscope. Bearing noise was clearly audible. The bearing noise was cyclical which indicates that the sleeve bearing is where the noise is occurring, not the steel thrust plate. The sleeve bearing noise was likely caused by a slight imbalance in the platters weight distribution and thus would shift the bearing laterally and create the bearing noise.

So, where does this leave us:

1. 60 lbs incremental platter mass reduced wow/flutter by 50-66%.
2. Heavy platter needs to be appropriately balanced to no longer cause the sleeve bearing noise.

The 60 lbs platter is not suitable for the current setup (see photos), as it was taken from a 17" OD Gates CB500 transcription table. So, I am considering a new high mass platter and bearing.

Meanwhile, the stock papst motor purrs like a kitten, albeit with the fan noise that is inaudible at the listening position.

More to come.

Pat

3D-printing waveguides and phase plugs

So my workplace bought a 3D-printer. Of course my first thought was: "How can I use this in speaker building."


My first speaker related print. Is it obvious what it is?

Hello,

I'm having trouble identifying the part used in the DNA Sequence for midrange reproduction.

From DNA Sequence Speakers dipole open baffle woofer high efficiency point source array midrange tweeter treble loudspeaker

"5.75 inch polypropylene sandwich cone midranges made in Denmark - possibly the best midrange driver ever made!"

I bought 25 of them a few years back, and I'm trying to build with them, but having trouble figuring out the right crossover point and enclosure arrangement.

The inductance is vanishingly low, and the transient response is very good, and the SPL is around 92dB if I recall correctly.

Thanks in advance for any help.

I bought a used BK 2120 scope about 7 months ago, and its been pretty faithful actually up until this afternoon. I know how to use it and have been using it on average about an hour per day since purchase.

The trace line for both channels just today quadrupled in height. Focus cannot get the trace line as sharp as it was even just this morning. Nothing has changed at all afaik but then again dealing with old equipment. The scope still works otherwise but very annoying not seeing that sharp trace.

I opened it up but everything seems very clean inside.

Foreign object to me. There are no pots for focus fine-tune adjustment within either.

Anybody know how I might service this?

Can an ammeter like this one, connected to my main line affect sound quality?

Black Digital Ammeter Voltmeter LCD Panel Amp Volt Meter Gauge AC 100A 80-300V-buy at a low prices on Joom e-commerce platform

If you don't feel like searching the thread..

PiDSP is on GitHub:
Sourcefiles[/QUOTE]

There is also manual:
PiDSP manual

Final(hopefully 😀) version is under way. You can watch the progress in development branch in Git repo.

I'm also pondering about having a batch of PiDSP boards profesionality made.
If you are interested, drop me a PM.


----------------------------------------------------------
----------------------------------------------------------
Hello everybody 🙂,
few weeks ago I've discovered the freedsp project and found it to be very interesting... but the ADAU1452 seems so much more potent dsp.
So I got in touch with the creators and joined the team with focus on new version with ADAU1452. I've been pondering about it for some time now, reading datasheets, researching, playing with possibilities etc.
Now it's time to open development thread and ask you about your opinion, feedback, and ideas, so we can make the next version as good as we can.


Flood of questions and ideas follows..

The general idea:
DSP, DAC, PSU - each on its own separate board, connected via wires, maybe backplane. ADC is not in my scope at this moment
PCB width 100mm - enclosures available, length 80mm(half eurocard) or 100mm, we will see.
Smaller builds could fit into extruded enclosure (hammond,fischer), bigger in rack

PSU board:
talema 70000K +- 15v for opamps and 48V(via voltage doubler) for phantom - no reason not to add it. will be useful with possible ADC board
Another transformer for digital part, maybe with double secondary - second winding for analog circuitry - PLL, DAC ref. etc.
I haven't made my mind about it yet. Any suggestions?

DAC
Stacked TRS 6,3mm - only way to fit 8ch to 100mm wide PCB, 8ch - why not 4x2ch? Big, expensive, I'd like the project to be accessible, and I like KISS principle. I've narrowed down DAC choices to following:
PCM1690 - cheap, available, even got samples somewhere...
AK4358 - comparable with PCM, number-wise
dual AK4413EQ, higher performing pin compatible alternative available AK4414EQ - really nice spec.
AK4458 - new part, isn't available yet, would be nice to use new stuff in the design though. I'll try to get samples.
Opinions (and experiences) about/with DAC chips highly welcomed. My life is too short to try everyone of them, so in the end I'll just pick one and go with it,If you have something to say about them, please do.

Why no ESS stuff? I'd like you to be able to buy all necessary parts at usual outfits (digikey,farnell,mouser...).
Yes, you can buy Sabre in single qty, no problem, but the shipping is prohibitive. And world is full of sabre dacs.

DSP board.
All IO should be brought out. Clocks on UFL connectors, others on 2.54 headers, signal/ground, signal/ground... SPDIF on BNC.
We could add MCLK input, its just a few additional parts and might be useful for some.
Number of I2s lines is limited, 4in, 4out more channels is accessible via TDM. I'm considering providing isolation on I2S lines, so you could use the board directly with BBB as a source.
Would be nice if one could plug BBB directly into the board - you even could program the dsp with it.


I believe it's enough for a first post. Opinions, advices, questions?

At this point it's just bunch of ideas, in the end it could be single board with XLR outputs.... Nothing is set yet... well probably DSP, oscillator, and LDO for PLL are set 😀 ... What I meant is if you think that single board(or XLR, or DAC XYZ) solution is better, say it and add why you think so 😉

Thanks for reading

Pitrsek


P.S.😛lease feel free to notify my about my spelling/grammar mistakes via PM.TY.

OK, long shot here. Taking FB to the VAS from the primary side of the OPT (output tube plate) is a simple matter in SE amps but is there a way to take feedback from the primary side to the VAS in a PP amp? If you take it from just one output tube it might be OK for normal signals but I am thinking that things would go completely nuts when there is an overload or even class AB operation. Reasonable assumption? Any clever tricks or just bite the bullet and buy a scope?

Can someone please identify this capacitor and where to get it, please. Thanks.

Hello! I'm trying to troubleshoot my preamp, one day it was working fine and the next day it had no sound! I'm very inexperienced with this sort of thing, and this preamp is pretty old, so google wasn't much help. I've checked the fuse, cables, and plugs, and I'm about to take it apart to clean the inside. Hoping there's a simple fix that I'm missing.

Hi,

I need to replace a broken ground connector on a Pass Labs XP-25 phono preamp, I have been looking for it or something similar at Mouser without luck.

Can someone tell me the part number that I should look for.

Thanks

Hi everyone!

Troubleshooting SMPS with output voltage fluctuation from 4.8V to 5.0V, spikes to 5.2V and back to 4.8 every 2-3 seconds.

Replaced with brand new: both optocouplers U6501/02, rectifier D6515, U6503 IC.
Primary voltage is stable 160V on C6506.
T6501 secondary side is stable AC voltage.
Diodes tested OK. Caps OK. Resistors OK.
Suspect D6524, but not sure....🙁

Any help is greatly appreciated!

Hello,
I am not an electronic engineer and my english is poor.
Sorry for my mistakes.

I work on this amplifier for a few month with MicroCap 12.
Here is the schematic, distortion with 1Watt output and phase diagram.

What is your opinion and your comments?

The power supply will be a SMPS from HYPEX + - 64V

One approach to gain more output power for single ended triode amplifiers is to drive the output tube to positive grid for class A2 operation. I found two different circuits on the Internet. One uses 12AT7 and the other uses IRF610.

Can someone with more experience comments on these two approaches?

The 12AT7 seems to be biased quite low. I am not sure it can deliver 4 mA for the 6S4A tube to operate at full A2. Can I increase the bias or change the tube to something like 12AU7 or 5687?

The IRF610 for 4P1S (4P1L), on the other hand, was biased at 42 mA. It looks like good enough to drive the 4P1L. However, what are the design criteria for this MOSFET? Is IRF610 linear enough? Are there better new MOSFET for this application?

Hi everybody !


I'm new here. I didn't find a place te present myself, so i do it here.


I'm a jazz/rock and so on guitar player from Belgium, always playing on tube amps for years and years.


One of my amp took some rock and roll on the side, and the transformer took a hit. on the side. (See picture below.)





My questions are the following : do you think the transformer is broken ? If not sure, do you think i can try to switch the amp on without damaging anything else than the transformer if it's broken ? (NB : the amp wasn't switched on when it took that hit and has never been switched on since.)


I don't have much of a peny to ask to a technician to repare it right now, but i still would like to play so hit singles if it's still working.


Thanks a lot in advance for your time and help.


Best everything you like,


Y.

Apologies if I’m brain dead and this turns out to be a stupid question. I’m building a tube amp and need to punch holes in the metal top of the chassis for 9 pin tube sockets. How does one precisely locate the holes? I have two PCB’s with two nine pin tube sockets on each board. I can’t just lay the sockets on the metal and trace around them because the PCB’s are in the way. If I lay the sockets on the metal without the boards to locate them, then they won’t line up when attaching the sockets to the PCB’s. I’ve been pondering this for weeks and can’t envision a solution. Any help will be greatly appreciated.

Hi there,

I need some advice on covering the holes that I had drilled on MDF to hold the enclosure box together after gluing, since i did not have any clamps to clamp them.

I want to get a smooth finish on the box and then want to paint it.


Any suggestions would be appreciated.


Thanx,

Tony

Hi all,
I am looking for a trusted repair shop for a turntable (Marantz Model 6300) near Houston, TX. This is for a friend - I am too far from him to work on it myself.
Thank you in advance for any pointers!

Need help identifying a missing resistor (RA31) in a Audiopipe APNK-40001.
Any help would be appreciated,
thanks

Hi guys,


currently I'm designing a class AB2 PP amplifier working with two pairs of GU-50's. The operating point will be the one in the rightmost column at page 9 of the Telefunken EL 152 datasheet. My PSU only provides 290 Vdc for the screen grid supply, though. In order to increase efficiency by decreasing the tubes' internal plate resistance, the supressor grids will be fed from +12.6 Vdc.


The datasheet doesn't read values for the screen grid resistors and especially not for the suppressor resistors, as this isn't a very common way to go. Which resistor values would you recommend, please?


Best regards!

Hello,

I am looking for only one 18S nsd1095n driver - 16 ohms version.

Many thanks !

Guillaume

Hello Folks,

I have an old and deteriorated bass reflex speaker with 8 inch driver tuned in 50hz and want to make a new enclosure

instead of make an exact copy the box i want to try some experiments

i want to try to make the same box with same tunning but instead of use a single port i want to use multiple ports like the project i saw in this old article


my question-

whats the benefits and disvantages of the distributed port enclosure compared to a single port bass reflex and why they arent so popular

hi- ive been recording with above-when i switch to tape from source the right channel drops 6db -i read that a standard din lead is wired wrong for the uher-
manual on hifiengine is missing the circuit diagram
the uher cable- is this differently wired?



-

I'm new to speaker building and I have two main questions, is it advisable to do a series parallel crossover in a 4 way speaker cabinet, and is this a good layout for my crossover in general, I'm not quite sure of the inductor layout. Also, I know the Caps aren't optimal but they were what I could afford at this time (I will be replacing them later).

Hello.

I have some pcb boards as leftovers of projects I already made.
In particular they are respectively:



2 "DC trap" boards
2 Boards for low voltage headphone amplifier with ECC82
3 Boards for s.s. "Canamp clone" headphone amplifier
3 Dual PSU with CRC filter boards

2 LM317 (+CRC filter) boards


See attached images. If someone's interested can write here or MP.

Thanks

My Class D with GanFET & LLC

I am working on a new Class D with Ganfet. Heres what I am intending to have it in the build:

LLC Switching @ 200kHz @ full load with PC95, PQ5050 using minimal gain to reduce switching noise during light load.

Target Operating Voltage: +/- 50Vdc
1Mhz Operation.
Paralleled EPC2207
Bridged Mode
Balanced/Unbalanced input.
DC Offset protection with MosFETs & Optocoupler as switch
Protection: OTP, OCP
All connectors are PCB Mount.
Common Chokes are used in all rails.

Cant wait to have this powered up!

And I name it as TOP DOG. 😀😀😀

Hello,
I am currently in the market for a 8" woofer to use in a 4 ways active monitor design and looking for some advices.

It will be used in a sealed box from 80Hz to 500/650Hz with a Morel EM 1308 so i need it fairly flat that range, low distortion is also a requirement. As for the Xover itself i'm using a dsp so fine tunning isn't an issue.
I don't really care about sensitivity either as my listening spot is about 1.5m.
For the material i'd prefer (treated)paper or composites as i'm not a fan of aluminium (my current woofers are alu i know their pros and cons).
And for the price per unit i'd like to keep it under 120€/130$.

After some research i had some candidates like:
-SEAS Prestige CA22RNY SEAS H1471-08 CA22RNY - 8" Subwoofer
-Peerless 830868 Nomex Peerless by Tymphany HDS-P830869 - 8" Woofer
But i'm open to any suggestions.
Thanks in advance.

hoping someone can help me get this amp sorted. i recieved the amp in a bundle deal years ago. finally getting around to use it and upon power up I notice the red protection light is on.

i have opened her up and see nothing burnt dark etc.

here are some pics.

Hi Everyone,

I have a step-down toriod transformer. Really nice quality, USA made.

Its 240v to 110V, 1000W

So long as the load is equal on both rails this should work to split the rails?

the load an amp puts on the rails should be symmetric right?

please ignore part values, its just for an example.

It just seems like I'm missing something.....

Just as everyone else, I am running down on my reserve of 2SK389/2SJ109s, and am looking for the best possible substitute.

The LSK389 is only available in N-JFET, and is not pin compatible. So for me no solution.

The most obvious solution is to use still available 2SK170/2SJ74 matched pairs. If you have a large pool, you can get them even better matched than the 2SK389/2SJ74 (spec at 3% match).

http://www.diyaudio.com/forums/showthread.php?postid=1689279#post1689279

But how about thermal coupling ?

You can glue them on the flat surfaces with silver epoxy, but you mess up the pin compatiblity to the duals.

So this is my solution. 😉

It has a factor of 3 more thermal contact surfaces than just gluing on the flat surface, for much improved thermal coupling, and is still small enough to fit in most applications, with a footprint of 16x8mm.

The heatsink helps to increase thermal insertia and hence thermal stability, and keep the temperature a bit lower than without.

They are not extrusions (with a minimum order of 1 ton in weight), but rather CNC wire-cut from solid. This also explains the rough surface finish, which is an added advantage as it increase surface area for heat exchange.


Merry Christmas,
Patrick

USB WiFi dongles confirmed working


COMFAST CF - WU735P
D-Link DWA-125 Wireless N 150 USB Adapter
D-Link DWA-182 Wireless AC 1200 Dual Band Wifi USB Adapter
Edimax AC600 Wi-Fi Dual-Band Directional High Gain USB Adapter
TP-Link TL-WN722N 150Mbps High Gain Wireless USB Adapter
TP-LINK TL-WDN3200 N600 Wireless Dual-Band USB Adapter
TP-Link TL-WN725N 150Mbps Wireless N Nano USB Adapter






Direct Ethernet(PC to PC, PC to Laptop, Laptop to PC or Laptop to Laptop) settings if you can't connect via WiFi a big thanks to Indiglo for these



Daphile Settings

IP address: 10.0.0.60
Subnet mask: 255.255.255.0
Router: leave blank or 0.0.0.0
DNS servers: 1.1.1.1
Search domains: 0.0.0.0

PC Settings
IP address: 10.0.0.61
Subnet mask: 255.255.255.0
Default gateway: leave blank
DNS servers
Prefered DNS server 1.1.1.1
Alternate DNS server: 1.0.0.1





if you know of any more please leave a comment with the name and i will update the list

Does anyome have access to actual in cab measurements taken from a Vifa M22WR09-06 driver?

I'm trying to sim a crossover and can't find anything other than the ancient Vifa factory measurements which dont help me with the in-baffle/box response.

Thanks

Here's a try using a Klipsch Heresy I with K22 spec woofer.

I may have not damped the port enough.

The Z peak, normally in the 65Hz region is flattened. Some peaking in the response curve shows (as does significant port output)

Hello,
Maybe some people on here will be able to answer this:
I'm looking to construct a Simple Speaker Protection Circuit using 2 x Back to Back Electrolytic Capacitors. To get reasonable Low frequency Response using a 12" 8 Ohm Driver, - (looking at commercial designs) - I assume that I will be needing a Capacitance Value of at least 2-3000 Microfarads to go in series with the Speaker Output. My Power Amplifiers run 60 volt Plus and Minus Rails, so I was thinking that 2 x 6800uF Capacitors connected Back to Back with a Voltage Rating of 40 Volts would be adequate. Somewhere else suggested using a Diode connected across each capacitor, with the + of the diode connected to the + of each capacitor would work better, to do with keeping each capacitor formed. At the moment, You cannot get Bi-Polar Caps with more than 2,200 uF at 25 Volts.
Here, I'm trying to get away from the idea of Isolation Relays or Series Forward Biassed Power Fets, because all of this can still fail. I'm looking to transfer no more than 50Watts of RMS Power, the rating of the drivers.
I'm sure that with everyone's vast experience on here, someone will know the answer! Thanks, and Kindest Regards - Telnet100

Building speaker cabinets I can do.
Building a crossover? Uhhh....

I'm building a pro audio cabinet. But the final design was just too big. I had to downsize for portability and the trick was that I would need a high pass filter for this box.

BassBox Pro Tech Support is telling me I need this:
What you need is an active 2nd-order high-pass EQ filter with Q = 2. This should provide a +6 dB bump at the filter frequency and a 12 dB/octave roll-off below the filter frequency.

Can someone help?
Maybe sample schematics or plans I could modify for my needs.

I'm open to any guidance.

I have around 100 120v:11.5v 80VA power transformers that I am trying to find a use for. They are basically factory seconds with various connector issues, etc. I also have a more or less unlimited supply of 26awg magnet wire from shaded pole fan motors of the same situation. I am thinking about cutting the "El" cores of the transformers open, 3d-printing bobbins and making "EE" core filter reactor chokes with an air gap between the "E" sections to prevent saturation because of the DC. Maybe lay a piece of fish paper between them for better insulation/separation. 26 awg isn't very thick, but I could wind several conductors in parallel for better current capacity. Does this idea have any merit at all? Is there a better way of going about it? All of this stuff is going straight into the trash if I don't snatch it up first, and I hate seeing it go to waste.


Edit: I also have a cache of microwave oven transformers as well, which I have done several things with. I've considered the same "EE core with air gap" format using them instead. They'd be huge, but I imagine the inductance would be huge as well. I'd of course cut the original windings out.

I just saw this article and I thought you guys might like it. It looks like a company created a special type of screw to help turn drywall into sound absorbing panels. I'm really curious how they perform. Considering the price of building a room with great acoustics this would be an amazing way to improve a room, as well as a whole house, for peanuts.

New Spring-Loaded Screw Turns Drywall Into Sound-Absorbing Panels.

The remote control seems weak.
Its not the batteries, they are new and have correct voltage.
Its for a quad77 cd player and the remote only works when close, say a foot or 300mm. What goes wrong?
Thanks
thyristor44

If someone from European Union has a pcb with Twisted Pear 9028Pro (preferably without Tridents) which he doesn't currently use, please pm me.

I am building a Troels larger box design and he uses quite a bit of internal bracing with nice round routed holes etc. With the current price of lumber in the US I found that steel bracing would be much cheaper on a cost per stiffness basis. Plus I prefer welding and cutting to routing.


So I am thinking of a rigid space frame internal construction and with front mdf baffle and sides attached to the frame. Still keeping the designed internal volumes.


Any big drawbacks to this plan?

This is a tough one, but a very serious inquiry and I am sort of desperate for a solution. I'm wondering if there's any way to lower the output impedance of my SP200 headphone amp, to better match the ridiculous 9 ohm impedance of my beloved Shure SE846 IEM's.
----------------------------------

Some background:

I recently upgraded all the phone amps in my recording studio. after extensive trials with every highly-regarded amp under $600, I settled on the SMSL SP200.
(Not the Massdrop, which I didn't test) It's amazing for the money, and after a psu cap upgrade, which tightens the loose LF, it's staggeringly good.

Unfortunately, I stupidly only tested the amps with studio cans, from 250-600 ohms. I forgot that low impedance IEMs might give different results. My Shure SR846 are about as low as it gets, at only 9 ohms. The SP200 was independently tested as having about a 1.3 ohm output, and yes the mis-match is extremely audible. Harsh, distorted, and a massive loss of LF.

So that's where I'm at. I REALLY don't want to start looking for alternative IEM's, although that may be the only solution.
=============================================

AND SO:

To be clear, I need lower impedance, not (just) lower gain.

I tried an inline resistor network at 80 ohms, but while this brought back the LF and lowered the distortion, it also killed a significant amount of HF. (resistance is not capacitance.) Ugh .....

Maybe a different resistor network design would work better? I know there are L pads, H pads, etc. They all drop the volume, but maybe result in different amounts of HF loss? But probably not, so on to possible amp-mod solutions:
-------------------

I don't have a schematic, so all of this will be tricky even for you guys. For me, it's like a chimp doing quantum physics equations. Well, regardless:


Idea #1: Maybe change the amp's gain structure, by lowering both the input and the output resistance?


Idea #2: Maybe add a little "buffering" circuit on the output. Unity (or even - 6dB) gain but with a super-low output impedance?


Idea #3: Maybe use a different op amp?
The two stock SP200 gain op amps are OPA1612A.

The Benchmarl HPA4, a $3,000 THX-888 design, uses 2 OPA 564 op amps. Surprisingly, (to me) It also uses a pair of OPA1612A dual op-amps as "error-correction" amplifiers.

The HP4A has a rated output impedance of “less than 1 ohm” .
Given my SE846’s 9 ohm impedance, that could actually make a big difference to me.

I’d LOVE to know why Benchmark used this alternate 20-pin power ic, and then used what the SP200 uses as some kind of ancillary circuit. What is “error-correction?”

And the obvious questions:

# Can the OPA 564 be used as a direct-replacement for the SP200’s 1612A? (I suspect not)

# If so, could it possibly have a lower output impedance?
- I’m guessing that this is indeed why Benchmark uses the 564, but then something in that IC requires the “error correction” 1612A’s to be added. In which case, there is of course little hope of a direct-swap.

The B1 thread is already bigger than 1500 posts. In this big pile of information I'm not able to find which JFET's can be used instead of the standard 2SK170/LSK170/2SK370 types.
Purpose of this thread is to make a list with suitable replacement JFET's for use in the B1 buffer. Any information on the performance of the replacement devices compared with the standard ones is welcome.
Some possible alternatives:
J309
J310
2sk117
2N5459

Preferably pro audio. Pair.

🙂

I get this board, you see "48V" on power input

you see on board LM2575T-12 (Input 45Vmax)
my board has LM2576S-12 (Input 42Vmax)

so, of course both can't be used with 48V,
because there is a direct connection form power input to the regulator.

so, I'm looking for a discussion on diyaudio with but unfortunately
all threads are longer than I can read

What can I do?
change the regaulator to LM2575/76 HV

I like to do anything to change the board to get the values from datasheet

Trying to simulate a bass tone controll.
Seems I get the same frequency responce at all potentiometer states.

What could be wrong...

I've noticed a quite few people seem to be having all sorts of problems using WinISD when trying to design speaker cabs. So i thought i'd explain how i do it.

Enter the Thiele Small parameters from the drivers data sheet in the order you see in my screenie.





A = Qes

B = Qms

C = Fs

D = Re

E = Vas

F = Pe

G = Xmax

H = BL

Pay VERY close attention to the terminology, as there are multiple choices available to choose from in WinISD. This is because not all manufactures list them identically. One incorrect entry and your design will we way off, and will NOT work as you hoped.

For example - Vas might be listed as 9.288 cubic feet, which is the same as 263.00 Liters in my screenie. If you carefully click on the appropriate position, in this case L as shown by the red arrow, you are able to change it to match what your data sheet shows.





Also notice how the text in the white entry boxes are coloured. Green, Blue and Black.

Green = Manually entered data

Blue = Automatically calculated

Black = No data

If you Carefully follow the above advice, then you should be now be able to design boxes more confidently and accurately. I've been using WinISD for many years this way, with great success both commercially and privately.

Happy building and listening,

Regards

Zero D

I have a halfler dh 220 that has the high end Fantasia upgrade with the turn on thump kit installed also . I have noticed a humm/vibration that happens about ever 45 seconds and last for about 5 seconds . You can feel it also if you put your hand on the amp while it’s doing it . Any thoughts this doesn’t seem normal to me ?

I have a updated Hafler Dh 110 that when I touch the Bass tone knob I get a hum through the speaker and also the knob wiggles when moves up and down and side to side . All other knob are tight . ? Any thoughts

It seems difficult and/or quite expensive to find a symmetric DC power supply capable of adjustable rails of up about 70 Volts DC capable of delivering about 5-6 amps.

In my possession, I already have a:

- 1000 VA toroidal transformer (120/240 VAC -> 2 x 50VAC).
- dual gang 40 VAC -> 40 VAC 10 amp variac (Powerstat 116CU-40-2)
- 160 amp rectifier
- about 200,000uF @ 200 volt electrolytics.

So I decided to do the following, please indicate if you see any flaw with it.
The idea is to feed the 50 volts from each secondary of the transformer to the 40 V inputs of the dual gang variac. The outputs are rectified and filtered and I get a very powerful (with very little ripple) power supply of up to about +/- 70 volts DC at about 10 amps max.

One issue I am thinking is that specific variac is specced to run at 60Hz. If I move this to a 50Hz country, I presume the max current rating will probably be less but does anyone see any other issue ?

I am adding a picture here:

Some years old but in top working condition build with top parts and the sound is verry good from this little chip amp. Plese se on pictures for more detail. Transformers are from Talema with 18V secondarys. The psu is build with Panasonic Fc 7 pieces 3300uf 35V per rail. There are four rails so all together 4 x 23100uf.The lm 3886 pcb are from Brian GT build with good parts like Amtrans and Takman resistors, Elna Silmic and Panasonic Fc and Nichicon capacitor. The speaker conector are missing but I ordered new one, so the buyer will become complet build, plug and play amp. The enclosure you must build by yourself. Sorry no time for this. Price is 250eu plus shipping inside EU
Or best offer.

For sale: transport USBridge Signature from Allo - sold

I bought this USBrigde Sig in March 2021. It has been used for less than 50 hours or so roughly. I only added a heatsink on the raspberry Pi CPU. The rest is original and working condition. It also includes an USB dongle (also bought from Allo) for wifi with very good range and speed. I also include the SDCard with Volumio pré-installed and including latest driver for the dual band wifi dongle.

Price on Allo.com: 239$ main board and 24$ USB wifi dongle (USD).

I would sell for 190$ USD for both or 170$ for main board w/o wifi dongle

Note: It does not include the power supply.

Shipping price needs to be added of course. Please specify preferred transport.

Fab

Hifonics VI Colossus amp half in protect

Started working on an old Zed Hifonics VI Colossus, which is essentially 2x Mono block amps I believe inside. Separate everything.

One of the amps powers up fine. Not sure if it will play though as I'm servicing the other amp which has the RCAs on it.

The bad amp, with RCAs, powers up for about 5 seconds or so and then falls into protect. My DVM is sensing +2~3vDC on speaker terminal which rises up to about +3vDC before the amp kicks into protect. Positive and negative rail voltage seems to be alright during that time. I found numerous bad solder joints which I cleaned up. Rail caps are testing good off the PCB.

There are no opamps on this board, only discrete components. Regulated voltage appears to be OK.

I've not seen very many VI amps.

Does anyone know what components I can remove to keep the amp powered up for testing, or any other thoughts as to why there would be +DC on speaker terminals?

Photos in a moment.
Thank you

Hi has any one listen to the DNA Sequence speaker or build a similar line array?

On paper its sound good, and I like the idea about line arrays, but until now it's has always been 2 or 3 ways systems for me.

So why did I start this thread? I just want to gather as much information about the DNA line array as I can.

Please tip in😉

Beginner's Chip Amplifier, HiFi LM1875, The Amplifier Board

This is for the purpose of an accessible hifi chip amplifier, it is in reference to Commercial complete Gainclone kit for a beginner? - diyAudio and it is by request. Here's LM1875, at low cost, and easily made by following the "play by play" photographic format (starting at post#24). The LM1875's "only 5 pins hookup," and the absence of spike system noise, can give you 25 watts per channel of high fidelity, at a bargain price, and with an easy time of building your own amplifier.

But, first, let's have a look at how "not" to use the LM1875: If you're planning the maneuver of pushing inefficient speakers with great force, then try something else. Our introductory LM1875 project here, has not been paralleled to withstand 4 ohm speakers.

LM1875 works great with efficient 8 ohm or 16 ohm speakers: Since this thread starts from Gychang's post and since he is famous for the full range hifi genre speakers, then I think that the laid-back hifi sounds of LM1875 could be a perfect fit. Any reasonably efficient 8 ohm speaker is suitable.

Circa 2012 update
Suitable transformer voltage is actually 18+18vac or less. These transformers are affordable: Antek - AN-0518 Monobloc/dualmono build is recommended for current control and wider imaging. For good longevity don't give an LM1875 chip access to more than 1a~1.5a worth of transformer. That's why Monoblocs really make sense.
Input load resistor should actually be 10k (not 15k).
Due to lack of NFB-shunt cap, consider adding high quality output cap assembly, in series to the speaker, for long lasting speaker protection. Adjust capacitance value to suit speaker size for enhanced headroom. Output caps strongly recommended if using irreplaceable speakers with Any chip amplifier kit or project. (click this link to see older nearfield design). The 2012 edition is a slightly refined version of the circa 2008 original, and suited to studio mixer/desktop use.

Circa 2013 update
With its gain of 34X, a computer sound card or digiplayer can drive this amplifier easily, without straining the source device. Now for 2013, it does have the NFB-shunt cap so it can't amplify DC. The parts paralleling shown is for high end quality at low cost. Output caps are no longer shown on the schematic but they are fun to use for bass and headroom enhancement. Tone option: To compensate for a peakish speaker, add just ONE of this model 4.7u from V+ to V- (rail2rail cap) at the amplifier board's power circuit to cause quieter midrange with higher resolution. Mains fuse and speaker jack fuse are suggested. Each monobloc produces up to 25 watts of power to an 8 ohm speaker.

Power Supply
Here are CRC power supplies for these monoblocs:

Option: You can use 3300uF 35v or 50v caps, such as Nichicon FW or Panasonic FC.

Transformer Voltage
Example transformer voltage is 18+18vac
Click on best match for your application to see a hookup diagram.
♦ Your mains is 120vac and your transformer is 18+18 or less?
♦ Your mains is 230vac and your transformer is 18+18 or less?
♦ Your mains is 120vac and your transformer is 36+36 or less?(dual primaries in series)
♦ Your mains is 230vac and your transformer is 9+9 or less?(dual primaries in parallel)
(please assure that the transformer output is 18+18vac or less)
And see Decibel Dungeon for a briefing on how to power your audio amplifier, including construction and safety.

Transformer Amperage
Greater durability can be had via good design and a right-sized transformer, or you could use a lot of fuses.
Monobloc/Dualmono:
♦ 36va*0.67=24 watts, which is perfect; however, we might want to adapt to dual secondaries and twin bridge rectifiers to maximize the little 1 ampere transformer. Use a mains fuse.
♦ 50va*0.67=33 watts, which is a bit too much; however, that's safe if given a Center Tap transformer (just one bridge rectifier) And the CRC power supply. Use a mains fuse and speaker jack fuse.
Stereo:
♦ 100va, instead of breaking chips, you may choose to use mains fuse and rails fuses for right channel amplifier board and rails fuses for left channel amplifier board and speaker jack fuses for each speaker. No matter if stereo or monobloc, a minimum of 7 fuses is mandatory if the transformer is greater than 50va.

Before powering on the new amp
Here's AndrewT's checklist:

AndrewT said:

Have you powered up via a bulb tester?
Keep this bulb tester in circuit until AFTER you have completed all tests and proved you have everything wired up correctly.
Have you powered the transformer alone and checked you have it wired correctly?
Have you powered up the transformer and rectifier and checked you have it wired correctly?
Have you powered up the transformer, rectifier and smoothing capacitors and checked you have it wired correctly?
Have you powered up the transformer, rectifier, smoothing capacitors and one channel of amplifier and checked you have it wired correctly?
Have you shorted the amplifier input and checked you have near zero output offset?
Have you measured the output noise with the input short in place?
Have you removed the input short and re-checked the output offset and output noise?
Have you connected your source and re-checked the output offset and output noise?
Have you tried moving the volume control and switching the source off and on and checked the output offset during all these changes?
Now you are ready to connect a dummy load.

Click to expand...

I would also like to suggest putting a capacitor in series with the speaker for protector. It costs less than replacement speakers. And you get the Bonus of fun bass efficiency tuning for maximized headroom (a lot more power), by simply reducing the capacitance size to match what the speaker can do and roll-off what it can't do. This makes your amplifier output only what the speaker can use. Cheaper: If installed at speaker ground of a stereo build, two speakers can share the protector.

Avoiding destruction
It may be very difficult to get up and running without the NFB-Shunt Cap, so here's a photo of the old 2008 project re-fitted for greater durability and so it won't amplify DC. This added part, NFB-Shunt Cap is the electrolytic cap in the upper-left corner pictured. Whatever else it may do, it is absolutely certain to give you better odds at building a working amplifier. So, use it.

I am planning to build a music system. I was searching around some amplifier boards, and I found these two PAM8610 2x15w and TPA3110 2x15w which are good but which is better? Also I am using 12.6V BMS 3S 20A 18650 Lithium Battery Protection Board to power the board.(also I heard that Pam8610 has some noise distortion and something)

hi I need help, I have a nad av 713 5.1 surround digital amp and it is making static and pop noises in both channels and in both speaker sets (A&B) I have tried cleaning the potentiometers and it hadn't helped 😡 also i have tried all the inputs and they have the same problem if anyone have any ideas of the culprit i will be more then happy tor hear

thakns

I am coating the interior of a speaker enclosure with these bitumen damping pads:

Solen Electronique Inc. | DAMPING PAD

The pad have a thick easy to remove plastic film under the self adhesive side, but on the other side, there is a very thin plastic film that is very hard to remove.

If I try to peel it, only small sections can be peeled peel off at a time, as the film has no elasticity.

Is it meant to be removed ?

I would prefer to leave it, because the pads have an unpleasant bitumen smell, and it would save the trouble.

On the other hand, felt needs to be glued to the pads, and perhaps the film is not a great surface.

Suggestions would be appreciated.

Hi guys I have 143x LME49990 to sell from an old stock I recently found.

101x Are new and unused, bought from Digikey in Jan 2016. 10€/pc
34x New and unused. Buy date unknown but must be before 2016.

8x Are used. 1€/pcs will only be shipped when buying new parts. Max 2/person depending on demand.

PM if interested.

Hi,
I've got a pair of beautifully made pyramid shaped speaker cabinets. Mixed wood finials with ebony.


They're 75cm tall, with a 30cm square base. The internal volume is 21L.


The cut outs for the 3 drivers are; 1", 4" & 7 1/2".


Sell the cabinets on, or invest in getting them working?


Cheers for any advice.

I am concerned about impedance matching of a microphone circuit. This is an electret mic.

Perusing standard XLR type audio cables, I don't see any impedances mentioned. This would be handy. Anyone know what this number might be?

I would assume the output of the mic and its associated circuit would match this at typical audio frequencies.

Thanks
Fritz