Hi all I’d like to start of by saying what an awesome group this is, I am a complete novice to all this so please bear with me.
We originally purchased a pair of Devine artists B15 subs but found them very quiet (500w RMS) the tops just completely out powered them so upgraded the drivers to Fane 15XS the volume was instantly better obviously as they are 2x the rms but just don’t sound right (amp is crown xls3500).
I’d like to put these drivers in THAM15 enclosure’s and would like some real world input, I like the thams due to their size as we are limited for space and as I understand would be good for output, any input is greatly appreciated.

Hi,

I’m just wondering if it’s possible to find an external “unit” or “device“ for use as oscilloscope and possible spectrum analyzer for audio equipment (up to 100 Khz. would be sufficient) using an iPAD or even an iPhone as display/processor. I know there are lots of apps using the iPad’s microphone for this, but that is not what I’m looking form. I want a direct electric measurement from a circuit, perhaps even with 2 channels instead of one.

Did anyone make it this way? Can we buy it? Where?

Any sugestions will be highly appreciated!

Regards, Gerrit

If this review is supposed to be in a different section of this forum, please advise.


Introduction
As an avid audio enthusiast, I'm always on the lookout for equipment that strikes a balance between quality sound, versatility, seamless connectivity and pricing. Especially when it is ‘above average for value’. The Arylic B50 wireless stereo amplifier is a such a product that stands out on multiple fronts.

Design & Build Quality: The first thing that caught my eye was the sleek and modern design of the Arylic B50. Its compact size makes it suitable for various setups, blending effortlessly into any space. The build quality feels sturdy, ensuring durability without compromising its aesthetic appeal.

Connectivity: The B50 truly shines in its connectivity capabilities. Both wired inputs & outputs and wireless inputs & outputs, make the B50 extremely versatile.

Wired inputs:

• Phone IN
• Line IN: CDE player
• Optical IN (e.g. Xbox/PS4 or 5)
• TV via HDMI ARC
• USB
• DAC (for laptop or PC)

Wired outputs:

• Wired (passive) speakers for stereo
• Wired (active) subwoofer

Wireless input:

• Bluetooth (in receiver mode) for smartphone, tablet or PC

Wireless outputs:

• Bluetooth headphone
• Bluetooth speakers

Bluetooth transmitter mode: One of the standout features of the Arylic B50 is its Bluetooth capabilities for receiving audio, the ‘Bluetooth transmitter mode’, sets it apart. This mode allows the B50 to transform into a Bluetooth transmitter, enabling users to stream audio from the amplifier to:

• Bluetooth-enabled headphones, providing a personal listening experience without disturbing others in the room.
• A set of 2 Bluetooth speakers. So yes, it can even connect to two Bluetooth speakers for stereo!

aptX HD: The Bluetooth audio signal is supported by aptX HD and delivers high-definition (HD) sound quality wirelessly. This enhances audio transmission over Bluetooth with the transfer of 24-bit high-resolution audio files, which results in improved clarity, detail, and overall audio fidelity compared to standard Bluetooth codecs.

Phono In connection: A standout addition to the B50's connectivity options is the ‘Phono-IN’ connection. This dedicated input accommodates vinyl record players, allowing enthusiasts to directly connect their turntables without the need for external preamps. The inclusion of the Phono input caters specifically to vinyl aficionados, preserving the classic analog sound while seamlessly integrating it into a modern setup.

Sound performance: Where the B50 truly excels is in its sound performance. Delivering 50 watts per channel, this amplifier produces rich, clear sound with remarkable depth and detail. The audio quality remains consistent across various music genres, offering a well-balanced output that caters to both audio enthusiasts and casual listeners.

HDMI ARC Integration: What sets the Arylic B50 apart is its seamless integration with ARC technology. The ARC-enabled HDMI port establishes a two-way connection between the TV and the amplifier, enabling the transmission of audio signals from the TV to the amplifier without the need for extra cables. This integration simplifies setups, reducing cable clutter and ensuring a hassle-free audio experience for movies, shows, and gaming.

User-Friendly Interface: Setting up the Arylic B50 was a breeze. The intuitive interface and user-friendly app made the initial configuration effortless. The app's interface is clean and straightforward, providing easy control over settings, EQ adjustments, and source selection.

Value for Money: Considering its feature set and performance, the Arylic B50 offers excellent value for its price point. It competes admirably with higher-priced amplifiers while delivering a comparable audio experience and a plethora of connectivity options.

Conclusion: In summary, the Arylic B50 wireless stereo amplifier exceeds expectations, combining impressive sound quality, versatile connectivity options, and an intuitive user interface.
Especially the Bluetooth Transmitter mode is something special. As most Bluetooth devices are limited to be a Bluetooth receiver, the B50 can also transmit via Bluetooth. And it is even capable of transmitting to a pair of Bluetooth speakers to create Stereo!
Whether you're a music enthusiast or someone looking to elevate their audio setup, the B50 stands as a commendable choice, providing a seamless and enjoyable listening experience.

Hello.
I’d like to try an 2SK1058 / 2SJ162 amp and would like to get your recommendation.

I don’t need very much power because it will be for an active system.

I would like it to be as easy and reliable as possible and it could be a kit or an already built unit
.

Thanks.

Can someone tell ME the value of Z9 and Z10 on a bogen black max 450 ??

After moving to active semi-OB, selling my Jordan VTL folded for Wall Mount (no BSC loss) : "Pentaline". Automotive Paint. EAD100HD.

I have designed them for wall mounting :space saving and better bass (used w/o BSC circuit)

Same internal volumes as initial VTL with the following mods:

• Folded 30°
• Upper chamber with non // walls
• bitumen + light stuffing

Great full-range sound. Can run w/o sub, however sub is recommended if you want to listen at a high volume (50W max). 6 Ohms.

Equipped with EAD100HD (slightly better response curve than original JX92S).

Medium 19mm, automotive paint.

Cost of build inc. paint : 900€.

Based near METZ, France.

Hi. I am looking for the transformer specs for the outboard power supply brick of a PS Audio IVH preamp.

I bought the preamp for a ridiculously low price without the brick.

It attaches to the preamp with a 4 pin connector, but according to the schematic, only 3 are used, and the tranformer is a 56vct. No secondary voltages are listed.

It shows 4 diodes for the rectifier with what looks like 1N4501 (7v?).

So would it makes sense that the transformer may have a 28v secondary?

One Bottlehead Paramour transformer - custom(?) Hammond H300668 like this. Thanks!

I thought it was worth creating a specific title in case anyone else wanted to use these.

I've finished a design and want to look at power levels in xover parts - just what they are intended for. Bit odd that they appear to report in dB rather the volts and amps. Sums needed to convert.
Anyway I'm using Boxsim 2. The only source of these I can find is here. Maybe there is another???
http://www.boxsim.de/SpecialChassis.html
The instructions translate well

So follow them and Boxsim produces it's red line of death and complains about missing data - the usual that comes with a speaker. The initial problem seems to be that the load defaults to data as per the box design - assumes they have been measured in this box. Change that to inf. baffle before or after a load brings up an error message saying not a sensible thing to do as a boxsim chassis will set this as it should be.

Oddly when I download them I stitched one into the default project it loads every time it starts. I managed to include it in the xover schematic. Looked at this again. I had it set in common box but have corrected that and all still ok, All with the same V2 software.

Any chassis load seems to automatically set it common box. Easily undone but no help,

I've tried every combination of loading them I can think of and no luck. Maybe I am missing some method? Or it just wont work full stop.

Maybe some load method will work? Maybe different versions are available somewhere?

I have n.4 Selectronic R-core transformer 230 primary 24Vac secondary 30VA. 20€ each or 60€ for. They were professionally modded from dual 15Vac to a single 24Vac.

A simple minded folk here.

I want to implement latest Hypex 500 or Purifi Eigentakt to fit my living room for tv watching(LG OLED) with a couple of speakers and a center channel (all of which yet to be purchased, except the TV).
I have no audio gear so I want to avoid purchasing an expensive Pre Amp.

I thought I could get away with a VTV Amp build, but there is no volume/remote.

Is there any need for a Pre Amp besides volume/source control in this scenario?
Is there any way around purchasing a >1000$ Pre Amp?

Meir

What happened to the thread "The new ESS ES9039Q2M"? It was locked some time ago but now it seems to be deleted. Why is that?

5 years ago I design and made some PCBs for a stereo PCL82 build. I've a few spare PCBs left over that are free if shipping is covered.

Schematic attached.

There are footprints to allow for the various designs floating around (shunt feedback, global NFB, triode/pentode etc).

These couple well with the power supply board here: https://www.diyaudio.com/community/...erlin-design-free-just-cover-shipping.406657/

I've used this combination daily for 5 years. Works very well for a kitchen sound system.

HI .
I would like to buy assembled PCB for state variable electronic crossover

Final Round for the DDDAC1794-PBT
Link to Post on my Blog Site

I will run a last production batch of the DAC-Boards (not the main boards) for those who still want to upgrade their current DAC with more decks. Or want/need spares…
But only if we achieve minimum goals and parts availability. These are the “Rules”:

• I need a minimum of ~ 50 boards and availability of the parts.
• You need to subscribe in the Response Form – See below Form.
• If you subscribe it is a binding commitment as soon as the last time buy is confirmed (enough boards and parts)
• Last date for subscription is December 10th.
• If minimum level is achieved and components are available, I will confirm, and subscribers will be able and invited to enter a purchase order at the Audio Creative Website. You also WILL have to make the payment at that time!
• The Special Web Shop order option for the last time buy boards will stay open till December 20th to avoid dragging this on and on.
• If all orders are in and paid for, components will be purchased, and boards will go into production.
• Expected start of delivery is end of February / beginning March.
• No returns possible

You can enter here for the group buy:

Go to the bottom of the blog post and enter the form:
Link to Post on my Blog Site


and look for this form:




Doede Douma
www.dddac.com
blog.dddac.com

Hi

OK, this is a longshot, but maybe one of you have experience with this.

Background: I have some odd/random failures in a FB (full-bridge) classD amp based on IR2184.
I have build HB (half-bridge) version, with very similar setup, but without this kind of error, so I'm trying to figure out why the FB is failing.

The only direct connection from one half-bridge to the other is the 2 SD ( shut-down) pins of the 2x IR2184. In my amp they are tied together (and can be pulled down to Vss with a transistor). - Could that be problem? I have a decent layout, acceptable decoupling and very short critical tracks.
Im pretty sure that the error only happens on turn-on (maybe turn-off, but only detected at the subsequent turn on).
I use SD to disable the IR2184 until supply voltage is high enough, and to disable if current is too high.

I remembered seeing a similar FB in an Yorkville subwoofer amp, but in that product the 2 SD-pins are separated although they are activated simultaneously .


Maybe not clear in the picture, but the 2 SD-pins are not tied together.

The circuit that pulls the 2 SD-pins high:

Why have 2 branches doing exactly the same?

Implementation on PCB ( With through-hole components...)


The only reason, I can see, for splitting the SD-signals, is that there is some distance from one IR2184 to the other IR2184 and maybe Yorkville designers tried to avoid tracks from directly from one HB to the other HB?

Any ideas?

Note: YES, the IR2184 have looong deadtime and distorts. I get below 1% in my prototype and thats plenty fine for a 500W sub-amp.

Kind regards TroelsM

Some time ago I purchased rather cheaply a KEF centre speaker with a Uni-Q driver which had a dead tweeter. As a bonus I got two iQ3 boxes, minus the drivers, just the boxes and the xovers inside.
My search for Uni-Q drivers did not produce a positive outcome, the Oz distributor had no parts available, eBay offered overpriced and in uncertain state options. So more or less a dead end.

Enter the SB Acoustics coax range.
It turned out SB Acoustics are producing a number of coax drivers and one of them looked a good match, its cutout and overall diameter are a very good match for the existing speaker holes, have very suitable T/S parameters, good sensitivity and so on.
The model is SB16PFCR25-04.
Ordered through the local distributor, WES Components, and six weeks later the drivers arrived.

In the meantime I stripped the boxes from their vinyl wrap, sanded and spray painted white.
Covered the internal walls with soft felt.
Fitted the drivers, needed to drill two extra holes in the drivers' frame to accommodate KEF's front arrangement and oh, magic, everything fits.
As a first step decided to use the original xovers and see how that performs. Next steps will be to try SB's suggested xover, and them my favorite - a 1st order Series.
But that will be later.

As a customary habit I always measure drivers T/S parameters and also always run an impedance plot before proceeding to further tests.
What struck me is how smooth the drivers impedance is, I only tested the woof part, and how smooth the overall speaker impedance is with the original xover.

Have been using this tiny dac for a couple months now. I am very, very impressed with it. Dual chips with balanced output and Xmos XU208. All for less than $100. Unbelievable. Better than my Dragonfly Red.

I opened it up and took some pics. Thought I'd share.

Hi, not sure if I selected the right category or not, but am completely clueless when it comes to anything beyond basic audio knowledge. (essentially watts and bass vs. treble is about the extend). However, I am fairly handy and capable of building/wiring/soldering if necessary.

What I am looking to do is add an external speaker via 3.5mm aux port to an existing Bluetooth stereo and/or Coyote Caller. If it’s possible to make one and it would work on both, great…. If only one, I’ll take it.

My goal is to produce extremely high frequency sounds that are very crisp and clear, not sounding like a bullhorn/siren.

We have a coyote problem, and they used to come into the caller periodically, but I think they’ve learned to recognize the “speaker” sound, and I’ve read if you can get cleaner “high-pitched” realistic sound from a 20,000-40,000 hz tweeter, it can trigger them more easily.

My question is this: Is it possible to do a DIY high-end tweeter that is either powered by the 3.5mm Jack, or could be powered by an external battery/amp of some sort?

The devices I would like to plug it into are:

-Lucky Duck Revolt Predator Caller : https://www.luckyduck.com/the-revolt-e-caller/

-Anker Soundcore Motion Boom Plus: https://a.co/d/3T6eELs


Thank you so much in advance.

Looking to buy Aya Dac PCB if anyone is willing to part.

Thanks for looking.
Regards,
Som

Hi

Mr. Marsh's excellent capacitor article from years ago suggested that low-value C0G-NP0 caps were low distortion and acceptable for use in audio amps. It seems today that it is almost impossible to buy old-fashioned single-layer ceramic caps as everything is MLCC. If the value is <100pF and the dielectric is listed as C0G-NP0 is the cap still acceptable if it is also MLCC?

MLCC = multi-layer ceramic cap

so I thinking of mounting the chips to the heatsink in this fashion (pics below and please ignore the spacers. those are there temporarily.)

The L-shaped aluminum bracket dimensions are 1.2in x 1.2in x 0.125in. i can also get (if these are better):

• 2in x 1.2in x 0.125in
• 2in x 2in x 0.125in

I will be using some thermal paste for better heat tranfer.

thoughts? Thanks in advance.

edit1: The bottom of the bracket will then be mounted to the heatink. (just stating this so it's clear)

edit2: The metallic thing with the black markings/lines is a 14in x 6in x 4in heatsink.

Anyone have any experience troubleshooting one of these guys?

I picked one up today that is not behaving properly. When plugged in, the amber power light turns white, as expected; lights on front panel blink a few times as expected; then the power light turns red briefly, then goes back to amber.

When holding down the "Bass EQ (SERVICE)" button in the back, which should supposedly put it into service mode for the purposes of re-flashing firmware, instead of the lights on top turning on, the lights on front turn on instead, which is not indicated as expected behavior by the manual or firmware updating instructions.

It's also not obvious how to get the thing open. It appears it's held together with plastic clips, but I can only relieve tension on one of the edges.. I feel like I'm missing something, and likely to break the cover if I proceed.

Uffornica Homestage in concept
She is a premium home entertainment audiovisual item featuring home theatre decoding, music playback and live instrument inputs with an integrated mixer and amplification

I have been developing an all tube based front end for my upcoming commercial bass amp with the premise that a live player should sound like a studio recording and not boom clash brash. I named this instrument Uffornica. The name is alluding to things like euphonic distortion and the almost sensual satisfaction of gorgeous music. The bass amp has an aux input for play along tracks and pro speakers from a different audio industry, in a one box 2.1 arrangement. As I developed this project, I found that this bass amp is making many parts of my home entertainment and home studio setup redundant, e.g. front channel poweramps, subwoofer, mixer, USB music player, Bluetooth receiver and everything that goes into connecting them all together. See we enjoy plugging in an instrument or mic and jamming along whenever the urge hits us

This inspired me to separate the electronics from the amp cab and develop it further where it takes the main duties in my particular home setup and the resulting concept I am naming Homestage

Project objectives
Form the hub of home theatre and studio
Remove clutter
High quality audio components
Dressed worthy of such a centrepiece

Dress up
I would like to offer my criticism of audio equipment aesthetics. A web search for amplifiers brings up industrial or lab look in the industry. Usually hard silver or black units. This is so boring, everything really looks much like everything else. Whether in hi-fi or pro audio. The internet is littered with clone build projects. So many are trying to make their guitar amp or Bluetooth speaker look like a Marshal. Music is a beautiful thing. The makers of makers of music, in other words the instrument makers, totally get this. The instruments are things of beauty, featuring a massive variety of colours and aesthetic ideas. What these instruments and their recording pass through look boring

If she is worth the best effort of DIY, then she deserves the best effort to be dressed fine

My design process
Usually I form a 3D, detailed mental image of what to build. I call this MAD (mind aided design) and then I go on to whatever lengths needed to bring it into existence, marrying form with function. The second setup for me is to transfer the MAD design to a 2D drawing, which is called a general arrangement or GA. This allows me to then start developing individual parts and working out fit to scale the GA. Then I usually use CAD if required to draw plans or just do it from MAD

Many of the chassis components will be bespoke e.g. panels, knobbery, switchery, PCBs and light effects. Build material will feature fabrics, aluminium, brass, acrylic and wood. I will be emulating the look of a process known as Menakari for the knob colours, which a colour coded for ease of use. The lightening effects are to complement our home entertainment light effects as well as for ease of use in a darkish environment, much like Roland's Aira lineup. A Roland JDXI will sit to one side of this and a Roland MX1 to the other. Together with a Mac mini desktop and a large screen TV. These and our string instruments are all the items that I want to take up space in the living area

These are the GA 2D drawings of Uffornica Homestage, I'll refer to it as Uffornica HS as well

Hi all, trying to assemble a music system that a tri of year 4 primary schoolers may plug various instruments into for practice. This needs to double up as a bass amp for my daughter for her electric bass classes at school. She is used to the little sub plugged into our mixing desk at home and like me she hates the weak uninspiring sounds that the usual suspects in the music shop make in the sub $1500 mark. Our usual listening and playing stuff is West Indian including dub

For $35 I found a group of four Logitech 2.1 systems that included the one that was the same z623 model sub we use. Issue was that this one didn’t have the satellites in lot. The left satellite contains the controls and plugs into a DB15. The right satellite plugs into a dedicated rca. Rear panel also has rca and 3.5mm inputs. The missing satellite has another 3.5mm input as well as headphone out, bass level knob, volume knob

In that lot there were satellites from LG as well ones for the other smaller three subs

I have a little USB/battery powered mixer with Bluetooth, instrument in and aux in

Also have two Kemo M040n black box preamps, 18 volts of battery, 18v dc wart, 9v dc wart, pots and passives for passive tone controls, passives to build four sets of the MPF102 jfet pres from another thread

Add to the list some knobs, wheels, mdf, marine ply, upholstery fabric, carpet, retractable handle from bag

Hoping to fit the sub and a pair or two of satellites into another new box and something the gyals may plug things like electric bass, upright bass pickup, mic, electric guitar, electronic drum set, tablet and like. Basic controls to find basic sounds

First challenge is to decode the DB15 pinout. I know that the pins for discrete input for the sub section and standby from the net searches. Plugged into this pin with the little mixer and bass guitar sounds sweet but the loudness is absent. Swapping the satellites from the home system and plugging the mixer into that returns the loudness

Now I am going to try to cascade (is this the right word, please advise) one Kemo into passive bass and treble tone circuit assembled from net schematics. That will be followed by another Kemo. Both Kemo will have 10k pots on the input lead. I’ll plug the bass into this and hook it to the sub direct pin and see if I can get acceptable volume and tone control

Hoping this works, then I’ll have the starting of a bass amp that my kid may find inspiring and satisfying to play

Next thing to attempt is finding the direct ins for main speakers amps in that DB15. For this I will need to make or buy a three instrument channel plus stereo mixer and 2.1 filter

As a side I have been curious about the MPF102 jfet. I have some and the parts needed to build some internet schematics. First attempt at building from random schematics as well as trying to learn about circuits like these pres ans mixers

Hope to find some assistance here if I get stuck. Thanks and regards

Randy

Hello all
I am thinking about making a sound bar type unit using three drivers only but still getting a stereo sound overall

I have a 10" driver with dual voice coils each 4R and a pair of 3" full range drivers that work happily when run in an active 2.1 setup. I would like to use these drivers with only a 2 channel amp and using a passive crossover on each voice coil of the woofer to run a full range

I have a two channel power amp board with a built-in mains power supply and has aux power outputs for preamps as well as fans. Insterested in making a custom tone control to control level matching between the drivers over using another amp to run them in 2.1

Most of the bass should come from the woofer so the passive crossover should be around 500hz

Is this kind of setup possible?

Opinions please 🙂

Hello,
I am new to this forum and apologize if I am in the wrong section.
I need help. As the title reads, I have a ppi amp that powers up, appears to be spotless inside, nothing looks burned or smells fried. I got it this way. I know it isn’t anything on my side because I swapped it for my other amp that is identical and works in that vehicle, this one just has no sound.
I am an HVAC Technician but this is beyond my skill.
Any easy fix would be awesome or if you know someone that could fix it for me, I wouldn’t mind paying. I prefer old school amps.
Thanks,
Scott Murphy

Recently i cam across the AP7311 is used in my 5.1 home theater system from true sound waltz. This is has inputs from aux/dvd etc and output goes to power amplifier. Clock and data lines going to sp3306 mcu. This AP7311 has 28 pins. This IC seems to be prologic decoder with audio analog input selection and digital volume controller. Can anybody help me in identifying this IC exactly what it is. Will be thankful if somebody share its datasheet as well.

Just quick questions:

What is the roll-off frequency of a transmission line and is there any difference between one without filling and with filling?

Does the taper change the roll-off?

Hey guys!

I have finally gathered confidence to design my first own crossover from the little knowledge i gained. would you please help me maybe improve on the design or give me some suggestions. I have tried to crossover the speakers at 200 and 2000Hz.
These are the drivers that i am using!
Tweeter: https://www.soundimports.eu/de/monacor-dt-100.html
Mid Driver: https://www.soundimports.eu/de/scan-speak-18w-8545-01.html
Bass Driver: https://www.soundimports.eu/de/scan-speak-25w-8565-00.html

Thank you very much in advance. keep in mind that this is my first crossover.

All items are in perfect condition and working order. Prices include postage to UK, overseas please enquire

TKD 4CP2500 Balanced 4 channel pot mounted on PCB, hardly used - SOLD

Academy Audio VCU MUSES all in one volume control, single ended very lightly used - SOLD

AMB E24 power switch driver kit, includes momentary power switch and power supply SOLD

(please move this thread to the new Horns forum when possible 🙂 )

It's a K-horn, which is short for Korner horn or Klipsch Horn depending on who you ask. The original was designed and produced by Paul Klipsch around 1946 and the rest, as they say, is history. https://www.klipsch.ca/blog/klipsch-down-low-horn-speakers

The design was licensed by the British company Vitavox and 20+years ago plans derived from the Vitavox version found their way to Ontario where various models were produced (and I know of an enthusiast who's still active and who helped build the boxes that now sit in my basement).

They are capable of good imaging so one need not be afraid of corner-situated speakers: https://www.diyaudio.com/community/threads/corner-horn-imaging-faq.248444/

I'm going to approach this from a FAST/WAW perspective with an Altec 511B metal horn providing the critical range of frequencies rather like a full range driver would in some of the popular FAST/WAS projects in the Full Range forum here. The driver on my 511B horn is the Altec 808-8a CD.

The box defines the woofer horn, so the only part left to play with will be the X-over and here there are many opinions.

FYI - I had originally turned down the opportunity to re-store these speakers after realizing it was boxes only with no drivers or metal horn and they are darn heavy but I was told that they sounded very good. Stereophile has this to say about the modern version "No one with a taste for realistic playback, and especially no one with a taste for low-power amps and high-sensitivity speakers, should miss a chance to hear these." https://www.stereophile.com/content/klipsch-klipschorn-ak6-loudspeaker

Hello there.

I have a Motorola Moto G9 Power that I will no longer use and I can use it for Spotify/Tidal. The screen doesn't work very well.

Wondering if the DAC is good enough for CD quality. Is it?

OTOH, if there is interesting software to install please let me know. Something that works like a streamer.

Hello!
I've recently 'repaired' an ARC D70. It was victim to a catastrophic failure, with the filter caps shorted with signs of arcing, a bias cap bulging and a blown 6550 tube. After replacing all the electrolytic's, a couple tubes (and re-biasing, of course) and some burnt out resistors, it sounds amazing!
The only trouble is that it makes a short zappy 'hum' on startup while it warms up (faulty thermister perhaps?), and every time you turn it off, there is a loud thump/pop in the speakers. I would assume since this beast has very complex (at least for me) power supply design, that this might not be normal operation- especially the shut down pop.
I'm running an attenuator from my source to the inputs, so no preamp to blame.

Any suggestions?
Schematic attached.

What's on your audio or workshop Christmas list:

Me, I would like a new Weller Soldering Gun.

I'm looking for recommendations for ouput transformers for an EL84 push-pull amplifier.

• The schematic calls for 8k and I need 8 ohm output, with a 4 ohm output being nice to have but not strictly needed.
• Solid bass performance required to 20Hz. Poor/lightweight bass performance is not acceptable.
• Rated 15 watts (or more) I suppose.
• Ultra-linear is not needed.
• I cannot use toroidals. They need to be a traditional transformer with end bells and wire leads.
• I do want a very good transformer, but I don't want to spend a million dollars on a pair either. I know there are some very expensive names out there.

I am looking for a solid performer that will not be light on the bass. A lot of transformers are available from China, but you never know what you are going to get, and most are only rated down to 30Hz which usually means closer to 50 or 60Hz in reality.

What high quality OPTs are currently available? Most links that I find no longer work or the product is no longer available.

WTB: BB OPA634AM in metal can.

Put simply, I have filtering caps run in series that need appropriate balance resistors. The set up is this:

• Two sets of two 270uF, 420V(max) caps connected in parallel.
• Those two sets are connected in series
• In effect, I have 270uF rated for 840V
• Using the following formula:
  
  
• and with the values:
  • n = 2
  • Vrated = 420V
  • Vbus = 497V
  • Imax_D_leak = 3 x sqrt(270uF x 420V) = ~0.001A (assumes no leakage in one set and maximum leakage in the other)
• I get an Rbalance of 343K

Here's the thing, I see a lot of schematics that have somewhat similar configs. They typically use either 100K or 220K ohm resistors (Merlin's PSU book recommends 50/C, which gives a conservative 95K). Few give ratings, and they range from 1/4W all the way up to 5W.

IMHO, the nearest common value for optimal balance resistors would be 1/2W, 330K ohm. Unless I calculated wrong, or am missing something?

I have read information for some time now, including topics on this forum. But I haven't found an answer yet. I want to use a set of 4 ohm tweeters in my car, high passing at 3500hz with at least 12db. I have looked at a Linkwitz Reilly crossover design and I got values of 5,69uF and 0,36mH. Here's the thing though. It's a budget build and the inductors I have found and are not said to be of mediocre quality (vented core copper for example) cost a lot of money. If need be for good quality sound then I will pay the money. But I was wondering if anyone has any knowledge how I could do this cheaper without much quality loss? I'm hoping not having to spend 30 to 40 dollars on a set of 2nd order high pass filters.

Trying something different, trying to figure out if this sort of thing is useful to make.. or ditch the whole idea. might try some things before i ditch it completely. i am thinking of making a higher one and using 2 coils for mid and 1 that reaches to 18khz.... making vertical dispersion as good as this one... maybe... interesting. while having much more surface area for mids !

here is a small video Login to view embedded media

Hi, from a surplus 1kg pack I got the following interesting parts:

1: Resistor, presumably hermetically sealed mil-spec.
Marked "Rdm1" with an Omega inside a delta

2: unknown, RTV covered, glass substrate, 4 terminal.
no significant capacitance between any terminal.


Anyone?
Thanks!

I just picked up 3 boxes of WWII radio repair parts that have never been used. Mainly tubes, transformers, resistors, and can caps. All of it is NOS so are the caps no good?

Does anyone have a schematic for a Counterpoint Solid-2 power amplifier you would be willing to share? Thank you very much.

Hello everyone!
I'm looking for the English versions of the Telefunken M15 and M15A Handbook, Operations and Service Manuals.
Actually, I'm looking for any documentation for the Telefunken M15 and M15A in English, even brochures.

I have a Telefunken M15A in working condition that needs to be serviced and calibrated. I have scanned PDFs of the Handbooks and some other documents in German but it's very difficult to translate and understand what you're supposed to do, especially because the manuals are not as straight-forward as Studer manuals.

@tmuikku I read a post on the groupdiy forum that you have these manuals scanned and asked that anyone else that needed the manuals should reach out to you on diyaudio. If you still have the manuals and don't mind sharing them, can you please send them to me?
I'm, posting this publicly so that other people can find this info more easily. Ultimately, if you don't mind, I would like to publish all documents and manuals somewhere where they will always remain publicly available for everyone, possibly on GitHub in a public repository.

I believe that one of the reasons why Studer machines are more popular than Telefukens is the better written and easily publically available documantation about them. Also, my current impression is that the Studer groups and forums have more people that want to help eachother out. I would like to change that and find a way to help other people with Telefunken machines.

Hey DIYers',

I've got a CR-820 which has a problem upon cold start-up - after the protection relay engages, the first 5 seconds of using the volume knob produces loud static noises. I need to wait a while to reproduce the issue, hence cold start-up only.

I have a feeling it's a capacitor - DC voltage on the pot would explain the noise, cap charge and discharge time would explain why the problem fades and then doesn't return until the amp is cold again.

Am I on the right track? Any tips on where to starting looking would be appreciated!

http://akdatabase.org/AKview/albums/userpics/10007/Yamaha CR-820 Service Manual.pdf

Background

With a halfway decent sound system, I started looking for new music to listen to. "New" meaning music I have no heard before, and that would mean a trip to the 1970s over again, where the music I like originated. As part of my journey, I came across, or to be more accurate, searched for and found Bostons song and "More Than A Feeling" and their also album "Third Stage" on my streaming provider. Interest in the band led me to watching an interview with Tom Sholz, who basically founded the band, and created that guitar sound that we all know and love. He said something intriguing: that he could never get the CD recordings to sound as he wanted them to sound.

https://www.diyaudio.com/community/...l-insights-as-a-producer.398525/#post-7331773

He said he found it difficult to mix for the CD format, and he was able to come up with a final recording that 'did not annoy him too much' as I recall he said.

If there really a problem with the CD format, then I should think of buying some other format. Maybe vinyl. Vinyl had that clarity, but it never impressed me with its bass output. The cassette tapes I have are now beyond restoration, at least to the level of quality I can now hear on the mp3s and CD recordings.Playing a CD or two, I could hear a somewhat metallic ring to the sound (I am able to detect the difference between some Digital amplifiers and Analog amplifiers over You Tube, so the effect is real)

Listening to the dreaded Crosley turntable reviews over YouTube again, I was able to hear a clarity that was pleasing: I knew of course better turntables connected to better systems would sound much better, and I was intrigued. I have ordered my first turntable and a record to test it with as well, it is, shall we say, a turntable that is not really recommended by anyone here. Think Crosley and you are not far from the truth. My journey has begun, it seems, hopefully not a false step.

From watching reviews of the lowest end of the turntable market (There was one reviewer who purchased a turntable for $10, it sounded ok but let's leave it at that), I was directed by YouTube to the very highest end of the market, it seems, the OMA turntable:

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I was listening to an incredible story. From the thousands of hours of research, to the cast iron casing, only 1 in 10 is acceptable, a powerful direct drive motor, and a dedicated motor controller, I could not believe the amount of money and effort that had gone into this design.

Was there a better way?

A Possible Solution

The main problem that seem to plague the turntable are variations in speed of the turntable and vibrations. You can add surface noise to that as well.
One approach is to maintain the speed of the turntable no matter what. The other is to try to correct for these variations. Immediately there is a problem, as OMA has pointed out, the variation in speed changes the character of the music itself.

Is it possible, and I know it is possible, I should ask how successful is it to use a method used with CD players and digital music, to convert the signal into digital format, and then store this signal in blocks of data for processing and correction, and then output that data to the amplifier at exactly the correct speed? The corrections will have to incorporate the following.

1. Corrections for wow and flutter using a turntable speed sensor as input
2. Corrections for surface noise from a 'surface noise library' that matches the surface noise pattern

Apparently there are some related patents:

https://patents.google.com/patent/US3983316

https://patents.google.com/patent/US3873764

Has this ever been attempted? If not, anyone on this forum may develop this further, I only ask that the idea be acknowledged, that it came from me in this post.

Hello all,

I have a Sony CDP 228 ESD with a problem in the CD reader.
Was bought en ebay a month ago and worked well while.Now CD is not recognized.
The loader tray works well, but the disc does not rotate, the laser head moves several times trying to focus, but the disc only rotates a quarter of a turn or less, and it goes like at intervals
I had read about pickup laser KSS151A,check corrient laser.
I have been able to measure the current of the laser while it tries to focus the disk for several seconds,then goes off. Its current is 54.06 mA, (the laser sticker indicates 51.3 mA)
Based on this, the laser appears to be within its life span (less than 10 mA increase)


But the first question that arises in my mind.
Could it be the CD spinning motor or could it be the laser ? How to rule out spining motor or laser head to begin?

Thanks in advance and regards

I have an old quad 33. It worked initially, but now it can be silent in right channel for a long time and suddenly it comes back. It happens once or twice a week lately. Any suggestions?

Sudennly I came with an error streaming through foobar2000 to Moode. Can't stream at all, Anyone can help?

Thanks

Hello.
Integrated amplifier ATOLL IN30.
Fuses F1 & F2 blown.
Amplifier power on with only F1 fuse no blown.
With 2 fuses F1 & F2 alln 2 fuses blown.
With F1 fuse and 60w bulb on F2 power on but the sound cut after 2-3 seconds and the bulb lights up a little.
All transistors are ok.

No service manual.

This thread is started as a continuation of a previous one regarding the effects demonstrated by changing the capacitors in the yamaha 1000's crossover.

I have now very crudely removed the crossovers and made them external and I have changed every capacitor with modern day non-electrolytics ensuring exact capacitance is copied.

The results were stunning! Now I thought the Yams were superb speakers with the speed and transparency of my stacked quads. However! With the above changes this is what I get with minimal burn in time mind! The volume output goes up significantly ???about 30% for the same volume position.

Increased detail and air around the musicians. For example in terms of detail, well known studio tracks now clearly demonstrate stunningly the background studio noises. In term of music,cymbals have more shimmer and decay. The complex harmonies that make up a piano note are more audibly felt. Voices gain body and tonal WARMTH. The midrange becomes less recessed and far more prominent. The realism is in fact enhanced further than before, and trust me in stock state the Yams are one of the best i have come across.
Bass is clearer deeper and more detailed.

Separation of complex multi instrument tracks are suddenly clearer and more easily followed.

During the conversions I initially did only one speaker first. I was then able to compare a mono track between the tweaked and stock speakers. It was IMMEDIATELY apparent by jumping from one speaker to the other that the tweaked version was clearer warmer and had noticeably deeper bass.

Now I can only conclude one of three things

1) the original caps may have been knackered
2)externalising the crossover takes away those magnetic and sound pressure fields that may affect them
3)the original caps were of a crap quality.

Then what if I built silver inductors? or changed the caps to ultra expensive audionote copper? Or upgraded the internal cabling to one of the well respected manufacturers e.g audio note ansp??

Exciting or what.

My previous speaker experiences in chronological order are
quad esl57 stacked
spendor bc1
avantgarde duo
audio physic avanti
harbeth 30 and 40
rogers ls3.5a
etc etc

the speakers are being used with the following set up

pink triangle dacapo and transport
jadis jps2 pre
audio note 300b silver signature monoblocks
audio note silver cabling throughout

My old tweeter were 2 inch 4ohms Kenwood

I am replacing them with new one I have sorted some tweeter can someone suggest which is should I go with.

Attached pics below.

Thanks

Most full range speakers are 8 in and larger. I'm planning to build an open baffle speaker with an included woofer. I'd like to use the Visaton B100 4 inch as the full range speaker. I was looking at the Visaton B200 8 inch first and noticed how much better the polar dispersion is in the B100. It seems to me that a four inch speaker would be faster and better localization too; but at a reduced volume.
Why not?
I'm planning to crossover to the woofer at 100-200 Hz to relieve the 4 inch of bass duty. Shouldn't that get me to a 90db output level? I don't need a lot of volume preferring smaller ensemble music -- and I have a JBL horn system in another room.
So right now I'm planning to build the Visaton No Box speaker about 25% smaller in height and width but not depth. I think I'd also offset the 4" somewhat to the outer edges of the pair. I'd use an electronic crossover and separate class D amplification for the woofers- Eminence Alpha 12a's.
Am I missing anything here???
Thanks for any help

I was recently inspired by a thread here with a NAD lat-fet conversion, and did some reading on lat-fets/amps, and now I bought two pairs of Exicon ECX10N/P20 lateral fet's to play with, and the idea right now is to put them in a Pioneer amp I have on the shelf:


Thoughts/comments? Any reason this amp is not a good candidate?
Plan is to remove emitter resistors, add larger heat sinks, possibly rework bias spreader, and compensation could be a challenge..

I've been bypassing the inferior sounding pre-amp section of this integrated by utilizing the pre out jacks as a power amp input. The DAC I have connected has it's volume controlled line out capacitively coupled, so I removed the bipolar cap C55 from the pre and jumpered across C3 at the power amp input. The sound quality improved in all areas aside from a quite noticeable low frequency attenuation from about 80hz down.

Space limitations prevent polypropylene caps from being installed, and I've read that PET or MUSE bipolar caps would offer little sonic improvement over the stock electrolytics. Any insight as to what might be causing this? There is no DC potential on the input.

Hello all,

I would like to inform the forum members that we have two new moderators on board. kevinkr from Boston and wintermute from Sydney. Both are old and cool members, I wish them good luck in their new task. Australia time guys you get one in sync at last. Nice.🙂

I have an old amp with a blown 2SC5169 chip. They are not easy to find and was thinking that I could just use two NPN transistors with equivalent specs. It really is just two transistors with a common emitter.
What do you think?

This might be a little out there but wondering if this might be viable- using the two tympani bass panels inside two "L" shaped panels to make sort of a SLOB slot loaded enclosure???

First steps in making a 2 meter planar transducer. More to come in my slow pace.

For starters I have an Audiopipe APDLO-16001D which is a dealer line series amp that can only be bought at brick and mortar stores of which there are only 3 of on the east Coast two in Florida and one in Connecticut. I live in NC right in the middle of them. I got lucky and bought it new in box from a guy local to me for $80 (so cheap I felt bad and tried to offer him $100 😂) as of right now replacing it is out of the question (with any amp at the moment for cost reasons) because of cost and distance, I am handy with electrical circuits and soldering so I would like to attempt to repair it myself with either new parts or parts salvageable from other amplifiers/electronics. So burnt up 3 of what Im pretty sure are mossfets, and one of the capacitors, that I can visibly see atleast. I called Audiopipe tech support and found out that it was likely from connecting the subwoofer with the amp already powered up. Something I had never had an issue with before or heard of. But I guess there's always something to learn. Also a few weeks back I could hear something loose inside the amp when I was moving it to its new location when I removed the cover it was a white ceramic box that was supposed to be attached to a post on the board labeled RX1 it had the same one opposite side of the board labeled RX2 still attached and the amp had been and was still playing fine with it disconnected so I removed it, put the cover back on and continued playing the amp with no problems until yesterday when I made the mistake that ended the amp. He told me I could email tech support for a schematic (not knowing what I'm looking at is 90% of the problem at hand, parts availability and money is the other 10%). So a schematic(if anyone happens to have one as Audiopipe has not yet replied) and parts list, potential electronics to find usable parts in and a second set of eyes that know what they are looking at and any other parts that may have damage that can't be seen along with any suggestions as far as what setting as far as volts/ohms/amps etc. and where/what to test with my multimeter for further diagnosis, would be super helpful. Attached are photos of what damage is visible along with an old Memphis 16-ST1000D that I could get some resistors and other common parts from if possible/needed.

TIA

I did some experimenting with the 19V Mofo versions of these amps and enjoyed them for the last 6 months. I saved some boards to try out some 24V versions in the future but need to sell these to fund other projects. I also have a Pass Front end to sell with one of the Mofo pairs.

- First amp is mono blocks in a single chassis with Wima caps, matte silver painted faceplate, Peruvian walnut bottom, and heatsinks cut to size and mounted together. 19V Dell Power supplies included. I used Hammond 193T chokes. - SOLD!

- Second is a pair built on separate Peruvian Walnut Wood planks. Only difference are the boards, the heatsinks are a tad bigger and run a few degrees cooler, and the caps are Solen. Asking $250 and help to ship

- The Front End I built into a Hammond chassis. It has an Alps Blue RK27 10k pot, silver Mil spec wire, Mark Johnson's SMPS filter, Nichicon BP caps on the input and Wima caps on the output. Powering it is a 48V Meanwell SMPS and it is set at 20db to run the Mofos - SOLD!

I am also open to trades for DIYAudio parts, boards, kits, etc to experiment with.

I'm after a pair of Inductors for my LuDEF PSU. Ideally <0R16 Rdc, >5mH, >4A

Either of these would be perfect:

Hammond 157E
Hammond 159ZJ

I'm in the UK

Sold sold sold….Here's four brand new KLE (Eichmann) Copper Harmony Phono/RCA plugs

Plus 8 of the older style Bullet plugs made by Eichmann. Two of the bullet are missing the little set screws. (See Photos.)

Free CONUS (continental United States) shipping. No international shipping. Not even Canada. Too much hassle.

$40.

I can take a Zelle payment or a personal check. Sorry, but I no longer take paypal.

Please know that I've been selling audio stuff online for ~20 years under the username Kolledog with perfect, 100%-positive feedback on all the sites. Never ripped off anyone. Have sold a few things on this site too.

Happy, merry.

Thanks.

Hi, I have used full analoge crossover for my 3 way floor standing speaker, vented not ported ( SP6600, Seas Excel W18EX and Seas Excel W26 ).

In the lately I have crossed between bass and mid / high with a Accuphase 2 way active fiter ( filter for mid / top is analog ).

Now I thinking of using only a 1 way active lowpass filter for the bass, and use the hole pasive for mid crossing down. And mid / top is as now.
Maybe I tell it complicated ( :
I have picture of the hole passive filter, all the bass parts goes away when using 1 way filter for bass. But I have to put back the 68uF serie cap and the 1.8mH paralel inductor ( did not use them when crossing with Accuphase ). The reason for doing this is that we ( friend and me ) have listen to some speakers and hear that the mid / top is gaining (play more freely and more detail / airy top from have passive crossover, compare to semiconductors ( opamp ).

1: Crossed at 200Hz before, testing 110Hz ( between 6.5" and 10" ), some advice here, pros / cons for where to cross?
2: The two parts that I have to put back (68uF and 1.8mH, have to change the value when change crossoverpoint ). What is that filter called, CL filter ?
3: Could I used a RC filter insted to cross the mid from low Hz, or maybe the cap and inductor is there for a special reason? I know the parts filtering upwards, the 1.8mH serie inductor is for rolloff uppwards and the paralell 10uF cap and 0.1mH inductor is a surge circut to take hand of the around 7000Hz breakup from the Excel 6.5" cone.

Puhhh!! Hope you understand the questions.

Frank

Hello folks,
here is a re-design of pcb of Rockola PA amp.
let me know your comments.. let me also know replacements of trannies.

I have tried to make it more convenient to build.
I am posting input circuit... output stage is coming up...
I will try to link the design, here or next post..
regards
prasi

Selling output transformers taken out from a working pair of Unison Research 845 SE tube power amplifier.
Looking for $350.00. Shipping extra.

Can't find the attachment's list (photos, drawings, graphs). - before there was a paper clip icon as link, near to each thread name
And now how can be done?
c

I managed to bring my Linear Power Model 120 amplifiers back to life in 2023... YAY. Made a video clip. These amps are STILL very POWERFUL in 2023. Login to view embedded media

I’ve recently been testing a basic e-choke for its frequency attenuation performance, as that aspect is somewhat lacking from what I can identify on-line. Testing has allowed a better insight into part selection and also general e-choke operation.

The test jig and e-choke circuit I used is attached below. A two channel PicoScope 4224A and FRA4 gain-phase software are used to measure the e-choke attenuation from ‘input’ to ‘output’, with a simple 1 ohm resistor load. The waveform generator output of the Picoscope is buffered/boosted by the venerable LM12 power opamp, which achieves a flat large-signal amplitude out to 100kHz, and -20dB out at 400kHz. The signal generator and FRA4 software allows a dc voltage offset to be included with the ac signal, which can then apply a practical DC voltage across the e-choke DUT, along with substantial AC voltage to allow gain-phase measurement across the e-choke, given that e-choke applications for say valve amps require an e-choke providing circa 100mAdc. The e-choke dc current is normally determined by the application amp's operation, but for the purposes of this test the e-choke dc current is set by applying a dc voltage from the buffer to the input of the e-choke.

The low frequency operation of an e-choke is explained in a few on-line references. In summary, the resistor divider R1:R2 sets the idle Vds voltage of the fet for a given e-choke dc current. This is done by applying a Vgs-on voltage consistent with the dc voltage drop across R3 and the specific Vgs-on characteristic of the FET used. For example, with an input voltage of 10Vdc, and Idc=100mA through R3=20 ohm, the Vgs-on=3V as R1:R2 sets Vgs-on + Idc.20 = 5V. In a class A amp application with a constant current draw, the idle voltage drop across the e-choke will vary somewhat as the FET Vgs-on voltage characteristic is temperature dependent, but would otherwise be constant.

An input ripple voltage causes Vds to vary similarly by way of C1 keeping Vgs pseudo-constant with a characteristic that emulates an inductance (effective impedance of the e-choke increases with frequency by way of C1 impedance falling with frequency). Vds negative swing is limited when Vds approaches FET on-voltage (~0V), so a symmetrical swing of Vds is about twice the idle Vds voltage – which then relates to the maximum incoming ripple voltage that the e-choke can linearly attenuate.

With respect to frequency response of attenuation, the impedance of C1 approaches zero above ball-park 1kHz, and so gain (attenuation rate) then changes from -20dB/decade back to unity. Above nominal 1kHz the effective capacitance across the FET (drain-source) starts to become significant such that FET impedance becomes capacitive and dominant, and the e-choke gain increases at +20dB/decade back towards unity. This frequency response is equivalent to that of a common iron-cored choke where choke impedance rises with frequency but then reaches a peak at the choke self-resonance frequency, and then falls as the shunt capacitance of the choke winding then dominates.

Of interest with the test measurements was the influence of FET capacitance. With an IRF840, the maximum e-choke attenuation reaches about -90dB at 1kHz before the impact of FET capacitance then starts to dominate, and at higher frequency represents a drain-source capacitance of about 2.9nF. The IRF840 has a datasheet Coss of about 2nF at Vds=1V, so it seems like the FET gate resistor and/or a Miller effect may be at play.

Changing to a MTD1N80 FET, with a significantly lower datasheet Coss of 320pF at 1V, did push out the frequency to above 10kHz where e-choke attenuation starts to fall, and the response represents a drain-source capacitance of about 510pF. Increasing R4 certainly showed a dominating influence.

This is all food for thought perhaps, although I don't think many have used e-chokes, and fewer have likely checked their performance.

Ciao, Tim
PS. excuse the error in LM12 gain, and the phase axis numbering in the middle plot.

Today is the beginning of the incandescent light bulb ban - 8-1-23 !
https://www.cnn.com/2023/08/01/business/incandescent-light-bulb-ban/index.html

What do we do to design a DIm Bulb Tester Now ?

Dear All,

Does anybody have the schematic of the x-over of the Grand Piano Domus ?
They do not have the post for bi-amping and I was trying to understand if this would be possible isolating sections of the x-over.

Thanks,

Davide

Hello all. I'm not a builder so apologies for only asking for help.

I want to replace the volume control on my lab12 Pre1. I'm doing this because
a) I can't find a preamp I like better (I've tried a variety of integrated in the $20k range and I always come back to my lab12) and so I want to hot rod this one as far as I can and;
b) I need balance control due to hearing issues, the volume control doesn't seem to land in my favorite listening volume when using the remote.

So I'm looking for top tier sound quality, balanced, with remote, and ideally an digital screen so I can see the volume, but that's least important.

I would say cost is no object but understandably I would rather keep it under $1000.

I do not know how to tell if one is technically compatible.

I won't be doing the work of installing myself.

I don't mind hacking up the case or building a separate one. That side of things I'm good at.

Thanks so much to anyone who can provide suggestions.

I own a pair of Sonus Faber Grand Piano Domus speakers and have a question: knowing that the two bass woofers in each speaker work in parallel, does the crossover send exactly the same frequency range for the two woofers or they work with different frequency ranges?

In the second case, what's the frequency range sent to the first/up woofer?

Thanks in advance.

Im trying to get a little 6j1 tube preamp (the fever/bile one, lol) i built from an ebay kit to sound right through an (I think) 22k ohm input impedance (generic class D, tpa3255). The output impedance of the tube preamp is 5k ohm =/- so far as i can determine with research. It has rising output impedance toward the low end of the frequency spectrum but quite low near the high end. And as far as im aware, the rule of thumb goes, it wants to see no less then 50k input.

My obviously wrong logic (as well as several youtube videos and forum guides) would dictate i should be experiencing very rolled of low-end running it into an impedance that's too low. And i can fix that by changing the included coupling capacitors from 1uf 50v ceramic to 1-2uf 50v film caps.

Well when i plug the preamp into the power amp, the opposite is my problem, all i get is low end. Id guess its rolling the high end off no higher then 5khz. Went ahead and did the coupling capacitor mod anyway, and as the problem would dictate, it made the issue got worse. At that point i assumed there was some components functioning improperly so i ordered the kit again, exact same issue.

For the hell of it i plugged the preamp out of my little kit tube headphone amplifier into the power amp. Exact same issue, but plugging in the headphone output sounds great. I do not have this issue with my DAC, my tube phono preamp, or any other line level source of audio i have.

To add to the confusion, they all sound just fine plugged into the 3.5mm aux input on the back of the phono preamp (Fosi x4), but fosi is not being cooperative on telling me what the input impedance of the preamp when used as a buffer only so i can actually understand anything i'm observing, i don't have enough info on my own. very much a beginner, and for whatever reason google has been all but neutered. Obviously it's going to be very high, it's a buffer. But no clue the actual value.

What am i missing? I'm definitely missing something obvious here, i've been searching off and on all day and cant figure out how to fix my issue. Should i drop the value of the coupling capacitors and see how that sounds? Im just learning as far as this circuitry goes and i dont want to damage anything.

Schematic of the amp in picture. And i am aware of the output resistor to ground error in it as well. I was able to remove the hum with a modification to the filter cap circuits, and into my fosi buffer and the yamaha s801 in the den, it sound phenomenal. So i'm pretty motivated to get the thing right for my bedroom/desktop power amp. The fosi x4 handles tubey imaging duties in the den just fine already.

Our Bose Wave Radio, model AWRCC2 always skips on the first few tracks of CDs. Has anyone had this problem or found a solution ?

Hello I have a question how to connect to the tpa 3110 xh-a232 amplifier using the bluetooth module, I already have this module connected, I mean how to connect the 12 volt battery to this design, with a connector for charging and how to make the current from the battery flow to the bluetooth module and also to the amplifier. Will I need an overcharge protection module or something else? A diagram of how to handle it all would be enough for me.

the amplifier I'm writing about
Bluetooth module I'm writing about

I have a bunch of lm338 left over from an old project.

Would an lm338 make good sense for powering an ACA mini?

Would a cap mx be superior?

Cap mx + lm338 overkill?

After over 12 years of perfect service, one speaker suddenly began popping loudly with approx 0,5 s intervals, sometimes a little faster or slower, sometimes buzzing, too.
The pop sounds a a bit like a relay klicking, too, but there isn't any relays in there afaik. It is likely the lower bass panel.
Anyway, I try to avoid opening them. If there any chance by letting the pop on for until whatever has crept in between the diaphragms burn out? I have put them on the side to hope smth moves in there and also hit them gently. No change.

Hi.
I have a Weilang Dac7 with USB and coaxial input. It only has a "dummy" optical connector. It seems like it was an optional feature and I did not explicitely ask for it when I bought it 10 years ago. Or maybe they "forgot" to set it up? 😀
I guess this is not an easy task but in case it was not so, could I wire the connector to make it work? It has a WM8805 spdif transceiver and I was reading this is then doable.
I gather I need the proper voltages from the PCB and I see there are +/- 3.3V. Where should I get the signal from? It already has got a switch to choose between USB and spdif input.
I think I found the schematics on the web but I do not know whether it is allowed uploading it here.
Thank you!