I recently had to replace one of those cheapo stereo B100K pots that china graciously sells in packs of 10+ on amazon. I did not replace it with the same, instead, while looking for an ALPS pot that would fit I stumbled across a "ladder attenuator". For those who don't know, the ladder attenuator is essentially a ~23 position switch that has actual resistors across the poles, such that each "notch" gives you a specific resistance for extremely stable volume control. Mine is 23-step and it fit without a problem even though it takes up a lot more space than the tiny B100K. Obviously I could not mount it directly to my preamp board, so I had solder wire leads to the attenuator, which then soldered to the preamp.

I honestly did not expect there to be much of a difference, but WOW there is a huge difference and in a good way. I don't really know how to put it because this amp already sounded good, but with the ladder attenuator no matter which volume notch it is set to, the sound is impeccably clear and the separation between the stereo channels seems to be a lot more defined and precise. This separation makes sound come across as bigger, with more presence and a "wider" span.

The most noticeable changes happen at lower volume levels. The best way I can describe it is like this: with the regular rotary pot, when the volume is low certain sounds are more prominent than others...so you effectively end up with portions of sound that are inaudible. With the ladder pot, as long as it is set to an audible level ALL sound is audible, even subtle sounds.

So if you are want to do ONE upgrade to your amp that will produce meaningful and beneficial results, try a ladder attenuator. I am using one I got from ebay for about $25 that uses "dale" resistors. They are all over ebay.

What cause this to burn and how to replace it

I accidently destroyed a chip on the board so If you have a board with a bad laser you don't know what to do with it, I could be interested to buy it. Thanks

Hi ... does anyone have a copy of the original Praying Mantis tonearm?
Lost mine long ago. It might be time for a 2023 upgrade after 45 years. Linears have short arms, could work again. I've built two in the past, but were too flimsy.
Zene

Hello everyone, hope this is the correct sub forum.

I’m working on finalizing my plans for the music and tv in our new townhouse’s living room. As commonly seen, I’m designing within the spouse acceptance factor. That being said here’s my perceived options, all active with dayton kabd boards.

I’m currently in the middle of building a 1.1 system with a center consisting of two rs100p-8’s sealed with the dc28f tweet and a Tang Band W5 sealed in .23cf. This would be a benign setup with very modest bass, the small subwoofer will actually have a high shelf filter to have flat response to maybe ~30hz. Of course overall spl will suffer greatly but the lady, and neighbor probably won’t enjoy percussive content after dinnertime, so the design will be low spl flat-ish bass.

With the rather pedestrian 1.1 system, I’d be in need of a small stereo bookshelf pair for personal music listening. This pair would be limited to a set of .23cf cabinets with an anarchy 5.5” sealed, peerless 1.5” fr and 5/8” tweeters. It’s not a very large room but the .5 cf bookshelves I’d like to build would probably be a little big looking.

The last option that I feel is realistic is gutting and restoring an old ~.44cf polk center with dual anarchy 5.5’s, a 1.5” and 5/8”. This option has the ability to be a one speaker system that would be too big if there were other speakers around the room but if sold as the only speaker I want to have, it would be an easy sell.

The main question is whether I should put all my eggs into one basket (gutted polk dual 5.5” center) have what I would consider a pretty nice speaker, or compromise on a small stereo pair and small 1.1 system. Would I even be able to achieve the stereo effect in a small oddly shaped room with small bookshelves close to the wall and one probably kinda in a corner? Because if the speaker placement/size will prevent the stereo effect then wouldn’t it be wiser to just go all in on a good center? Two eq’d anarchy 5.5’s on ~150w model more than enough spl for what I’d realistically ever use. I could program a knob to attenuate bass depending on the time of day.

I appreciate that among amplifiers this is probably the easiest to point to point, however I am trying to package this neatly, so am on the lookout for pcbs...
cheers
edited to add that I am asking for any availability of boards that I would propose to buy. I am not looking for a charitable donation...

Hi,
I finished the PCM 2707 based DAC. The DAC is based on the recommended topology by TI. It works, however it reproduces sound with some very weird distortion, where some of the frequencies got echo. The specific sounds are audible many times with continually decreasing magnitude (with 4-5 audible repetitions). Does anyone have a clue what might be an issue? The sound got the same signature as if I was using old WINDOWS XP sound echo chamber mode. Just to be more specific: I used different USB cables- it did not help, also checked sound settings and all enhancements are disabled. I was not able to find much information about this chip on forum. Some photo attached. Here is a link for the project:
https://hackermagnet.com/usb-dac-pcb-with-pcm2707/

Well, you know I've been on this site for a while and I've had an end game in mind for my stereo system. These days I find myself convalescing to some degree, so things are pretty slow around my house, so I got the time and all the hardware. This project is based on what I think would be the best diy system to play with building active speakers and have the most flexibility when tuning a multichannel active speaker system while still having a way to easily switch back to an everyday system that can run a fully passive system for everyday listening that doesn't consume as much energy.

Recently I was able to horse trade for a dbx 4820, well I don't need to tell you that this is just what I was hoping to base this entire system around. It has direct balanced digital inputs, room correction, a multitude of features for sound contouring and measuring. I guess I could have gone the minindsp way or deqx but these solutions just don't seen as interactive and I just wanted to take another approach.

The only problem with the 4820 is there is no easy and cost effective solution to controlling all the 4820's channels volume simultaneously. It needs to be good quality. What I really need is a serious 6 channel preamp that also has a feature to run a separate amp and speaker system for everyday listening. I scoured that net for something suitable and came up with the Thule PR350. This is a really decent analog preamp, looking a bit more into it reveals that it has a completely seperate digital and analog sections and the seperation between the circuits (for the most part) it controlled by mechanical relays. That sounds like it would be super simple to modify into exactly what I need.

So the features on this preamp that I will use are the direct 6 channel RCA input to control volume on all 6 mono amps powering the active speaker setup and then the preamp also has a feature to have a separate direct XLR in to XLR out with simple buffer and volume to control the passive setup. The opamps are mostly OPA2134. These are excellent quality opamps. The volume control is handled by several lm1972 ic based volume control chips. These are excellent volume control ic's and are still in production today and seen in some seriously high end gear.

So you see how this project is going to play out, I'm not really sure anyone else is going to be interested but for the curious I will post my progress on this thread. The first step is repairing the Thule, it has some blown opamps but the control circuit is in great shape. I've used this preamps direct XLR feature for many years. It is a really high quality direct volume control. The circuit for this feature even has it's own little, highly regulated power supply. It's a beautiful preamp.

Another thing I'm going to do is post lots of nudes of the 4820. I've scoured the net and can't find any and I don't know about you but I love looking at nude photos of gear and I hope this helps others on their quest by making these available.

Hi guys,
I need a good model for a triode suitable for a cathode follower that can swing some 300V pk to pk.
One candidate i have in mind is the PC92 because of the 250V heater to cathode rating.
Does any of you have a model that would work in Circuit Maker (3f4) or could easily get adapted to.
Other suitable suggestions/models are welcome
Thanks,
Pete

I need input buffer for baxandal tone controller. Schematic is given below
Thanks in advance

Nice verry little used pair of chokes. Price 110 euro plus 16,90 euro shipping inside EU. Payment by paypal for friends. This cost new 110eu each by Don Audio Germany.

I was hooking this amp up and like an idiot I wasn’t paying attention and the ground wire hit the positive terminal of the battery bank

It blew 2 traces on the bottom of the board and also took out a couple of power supply fets .

I fixed the traces and I am going to replace the power supply fets and drivers .

Is there anything else I should check to make sure nothing else got shorted ?

The output section seems to be fine
The power supply driver board in the amp is the same clone as all the other big amps

I find this sonogram from Dibirama site very useful. Very informative and understandable how the driver sounds.

What program can export flat sonogram like this?

LM4780TA Diy audio amplifier kit included power supply PCB 44€ more shipment
LM4780TA IC with PCB more power supply PCB with connectors and pré amp pcb.
Tracked shipment,shipment to US on request
Skematics sended together with articles
Payment by paypal

So I mistakenly posted this in solid state. Any ideas?

First time poster (long time lurker 😁)

I’m trying to drive a 3e tpa3255 module with a differential signal from an adau1701 DSP via I2S by feeding a pcm5102 module (the common purple one) with a mono signal on the left channel and the same mono signal (but inverted in the DSP) on the right channel. It seems to work but sometimes when I remove the inversion I can still hear some signal, when I’d expect none (except some noise from slight variations in the output stages). Maybe interference on the I2S?

Anyone tried this? Should it work? Any downsides? Any tips?

Keen to use this approach to keep weight and noise down and quality up in a portable PA party speaker.

Thanks for any help!

I’m intrigued by this newish design from Bert D that appears to be a horn / SLOB hybrid. In particular I’d like to understand the arrangement in the throat area of the woofer array. Any body got any insight into the design?

Hello. I have a pioneer pl 71 down in my basement with speed issues. (runs way fast) One of the 502 potentiometer on the motor PCB is literally falling apart. The metal slider has come off.

Is this 502 pot interchangeable with one of the Chinese made 502 pots available on ebay? Are there better quality components to be found? I've been looking at 5k ohm trimpots at website in my home country, and there are many different kinds ranging from 150mW - 1 W. Is this a important factor?
Could I play around with a multimeter to find the correct rating?
I have been looking at the service manual , but I can't really tell if there's any relevant information there.
As you might have guessed by now, I'm very much a newbie in this field.

While having had the turntable serviced by an vintage audio repair shop, the guy said the whole motor was probably shot and in need of replacement.

I however have a hunch that this 502 pot is the culprit.


Wanted to get some feedback from someone with some experience working on electronics before shopping for multimeters, random parts and soldering tools 😅

Any help is much appreciated.

Hi,

I have an Aiwa DX-666 which will not read CDs. The spindle spins up for about 10 secs then stops, and 99 appears on the display. Everytime I hit 'play' the same thing occurs. The RAFOC unit is a CDM-4/14. With no CD in the drive one can see that the radial arm moves to the innermost position and the lens moves up and down a few times. I have measured the laser current which is 50 - 55 mA, and the eye pattern is about 2 V pk to pk on a scope however this is not a clean pattern (more like a bird's nest) as the spindle stops turning after about 10 secs which is not enough time to adjust the scope trigger etc. I have re-capped all the electrolytics on the servo - preamplifier board except the bipolar one.

I have a Service manual but it is for a CDM-2 so I am not sure if the test procedures and given measurements would apply to the CDM-4. The manual mentions various 'service positions' and how to select these but not service position1; I have not attempted to set these yet. I would be very grateful if anyone could offer any advice. I am not familiar with repairing CD players and to be honest am feeling a bit lost so any help would be great.

Could I also ask if anyone knows where I can download a service manual for the CDM-4.

Many thanks.

I had to buy an isolator from usb ground noises from my puter to my DAC, i decided to buy two,

the IFI AUDIO ISILENCER https://ifi-audio.com/products/isilencer-plus/

and the wisdDenfender https://wiki.wisdpi.com/wisd-audio/wisddefender

My DAC's USB cable is 5m long, pluged on my pc's USB 3.0 back port,

the IFI does half the job removing most of digital noise, but still a lil wind blowing noise at high level at $70

my surprise was the Wisd device, it removed all noise, as if it was a toslink optical device and at around $40 priced, for 3 dongle, usb < usb, usb C< usb, usb c < usb c pack

Sometimes dearer doesn't mean better.

😉

HI, Ive had two of these chips die on me two different boards unexpectedly. Does anyone have a couple theyd part with? Its

XL7015E1 used on TPA3255 boards. Let me know. Im in US. Ty​

I can't figure out the deal with this ps. The wave going into the drive transistors is clean the output is like this.

Good morning, I just recently put together an amp with these amp boards without reading up one the issues they might have. One is oscillation and it was recommended to charge the 1K resistor to 910 ohm one. The AC ripple is near zero on both boards and the DC offset is 6 mv on one board and 10.5 mv on the other. I have not changed the resistir yet.

I have an Leader old analog scope that is 20Mhz with dual trace and a 1khz sine wave is not very steady with the peaks fluttering around and I cannot seem to drive a signal through the other channel.

First of all, I have not used a scope that much, I do, to check power output mostly on the projects I build so I can provide details to a potential buyer but I need some advice on checking for other issues. I always put in speaker protection and make sure there is a Zobel network and a Thiele networks as well to quell most issues. I do not want to have someones speakers burn out because of an amp issue. Is there a proper procedure to check for oscillation on a scope and what does it appear like on the screen. ?

Any advice would be helpful. I have hooked up my old test speakers and the sound is good, but the balance seems off a tiny bit, could be my preamp or my ears as well.!

Thanks Wayne

I heard a speaker yesterday that had superb tight and tuneful (multi-note) bass. It utilised 2 of these 15” woofers per side and the following information was provided in the blurb; reinforced paper diaphragms, 800W power handling, 4.5” voice coil, aluminium demodulation ring, twin spider suspension, ferite motor and +/- 14mm excursion. Sensitivity must be in the 90s. Here are some photos:




Anybody know what these woofers are?

Hi - looking to replace surrounds on Tannoy Arden mk1.

I see a very complicated process posted on utube recommending using voltage to raise cones etc - though also note some of his difficulty was due to having non-notched surrounds, making it very difficult to navigate round the cone reinforcements.

I have reconed quite a few drivers easily using common sense and general practical skill (regular simple woodwork projects and model aircraft on a basic level).

So;
Without using specialist equipment mentioned , and with the experince above; how do folk rate the Tannoys in difficulty - is it easy to imagine me accomplishing the re-surround or are the SGM-15 drivers a league to far in anyoine's opinion.

I notice the foams on mine appear to go underneath the reinforcements - N.B. I know this speaker had a recone early 90s at the Tannoy factory.

Any bits of advice etc welcome.

thanks.

hi, i'm new and i need help with the loudness circuit, luxman l114a amplifier 48 watts per channel
The volume potentiometer is broken, I found a new one without loudness socket ALPS 250 kohm logarithmic stereo which is ok
the loudnnes circuit formed by C 115 and R128 is now connected to the potentiometer output pin where there is R201 but the loudness effect is heard only at high volume, before at low volume it was felt a lot
I would need the loudness effect to ALWAYS feel like a low volume LOUD, and I would adjust with low tones and if I turned it up I would deactivate it with its key but I don't know how to do it thanks

circuit VR101 potenziometer volume, R128 and C115 loudness ,R201 in ampli

How do I get access to the power supply PCB in this CR-3020? Manual says to remove two plastic rivets on top side of chassis. Done. But the board isn't budging, and it has a boatload of wire wrapped pins along one side. TIA!

2 R Core transformers 2X27Vac/430VA
50 Euro/piece
Europe sale only
Shipping not included

Hi, recently i went biamped on my system using what i have already, i ended up using a old BIAMP SM23 active ross over. since it was all messed up with inside i made new pcb'S and removed the balanced line in/out circuits, because i felt that using RCA cables (home audio) would mess it all anyway.
Problem is, whenever i raise the gain input pots, i get opamp noise/hiss, that comes inevitably from the source a bit.
So, i post the simplified schematic of the BIAMP thing. yes its old and i know there a tons of better things on the market, no need to argue about that...but for the sake of knowledge on this, what would be the main problem with this circuit that would generate this much hiss noise ?

all resistors are 1% metal films
opamps are LM4562.

one thing i found is that when i reduce R1 100k down to 47k, with nothing attached to the input, the noise reduce by 50%.
thanks for any input.

Hello I have 3 Tripath evaluation board RB-TA3020 for sale at 76€ if you need power supply pcb
Included Sanken rectifier bridges and connectors is 18€.
Here populated power Supply shown as an example
Tracked shipment shipping to US on request.
Payment by paypal

Hello all, i think this question could also be answered by people who use the older CSR6xxxx chips as well, i like to use the QCC3003 bt amplifiers as for their size and ability to quickly hook up to a USB/SPI and modify the EQ settings they make great lowfi portable options.

My last project i used the same amp, 3d printed my version of an 80's ghettoblaster and had a great time using it with a nice combo of DMA45's and ND90-PR's. One thing that let me down as that i used about 4-5 3v LED Diodes and significantly slashed the run time of the singular 18650 battery.

As i need to fix up the voltage step up module as i think it failed, it made me think if i could save some of the battery life by attempting to solder 2 LED bulbs directly onto the chip itself, so then they actually have some purpose when the button is activated. Watching a video using the CSR6xxxx chip variant, it looks like a guys managed to do this as it uses 5v (apparently), so was hoping that as it was already pulling down some mA's that i could save by utilising the same. Has anyone done this with any of the variants and is it possible?

I would still like to know if anyone has managed to upload an audio/wav/mp3 to these chips to use as the intiation/bootup sounds, as i beleive it can be done, but might be a little tricky.

I have for sale a brand new SPA1000 plate amplifier. I've opened the box and tested to make sure the unit is functional, but it is otherwise unused. I meant to match it to a Dayton UM-18 Ultimax, but decided to go in a different (smaller) direction. I have already sold the Ultimax, and am finally getting around to listing the amp. Now I just have an SVS 3000 Micro, and it does the job fine for my smaller room.

Price is $365 OBO plus shipping.

https://www.parts-express.com/Dayto...ign=18197889536&utm_content=&utm_term=&gadid=

I also have the Dayton SA-1000 amplifier, which is exactly the same thing, except it is in an external chassis. Same price ($365) for that one OBO plus shipping.

https://www.parts-express.com/Dayto...ign=18197889536&utm_content=&utm_term=&gadid=

Hi, are there some fake Shinkoh resistors on the marked?

Here are two set of resisrors, the right ones is from Hificollective.

As I understand are they NOS.
The left ones as I remember I got from another store ( dont remember witch ), suppose to be Shinkoh.

Frank

I am trying to understand why the 300B amps I have been working with have distortion much higher than what I see others reporting.

Most people I see posting FFTs show around 0.5% THD at 1 Watt out.

I have two each Psvane, Electro Harmonix Gold Lion, and LinLai WE 300B tubes. These vary from 1.4 to almost 3% THD at one watt into an 8 ohm load with the amp depicted in the attachment. The opt is a Edcor CXSE25-8-5K.

The driver is a Hybrid Mu-Follower set to 6.5mA. The schematic is missing the cathode bypass cap (1000uF). The driver is capable of 0.05%THD at 50Vrms with selective tubes (12GN7) The current driver is a 12HL7 which is giving between 0.13 and 0.14%THD. At this level, I do not expect much harmonic cancellation.

The drive voltage at the 300B grid is about 20.8Vrms for 1W out (varies slightly depending on the output tube).

Filament supply is a 5VAC transformer, bridge rectifier, 10mF cap, two 0.3R resistors and a second 10mF cap.

I have chosen an operating point from the WE datasheet of 5K, 350Vak, -76Vgk, 50mA Ia.

The measured operating point ended up at 349.8Vak, -78.6Vgk and 55mA Ia. This varies slightly from tube to tube.

The only configuration which achieved 0.5%THD was removing the bypass cap from the 300B Cathode resistor with one of the EH Gold Lion tubes. Unfortunately, this resulted in high IMD (0.1% vs 0.003% with the bypass cap) above 3KHz and thus is not acceptable.

Testing with the worst tube for THD (one of the Lin Lai) I tried several different resistors including Wire Wound and metal oxide film I have the following:

Ohmite Brown Devil WW 12W-------2.91%
Dale RS10 -------------------------------2.67%
Chinese Metal Oxide 5W parallel-----2.55%
Vishay WW 5W parallel----------------2.96%
TE Connect metal Oxide parallel------2.66%
Dale RS 5W parallel---------------------2.65%

I was using the ebay Chinese Metal Oxide resistors in my original builds, so I will continue using them as they show the lowest distortion.

I also tried a variety of bypass caps including Ryubycon Gold 82uF, United Chemcon Low ESR 330uF, and Epcos B32926 film capacitors (15uF). Anything 15uF and above seemed to have no impact on frequency response. None showed a difference in distortion.

What's good enough. Well for those seeking quality, luxury and hi end goods its a straight forward issue. For audiophiles that's another matter as what is being sough for is angelic reproduction, even this is never quite right. Insurance doesn't yet cover this condition. Here's some nice sound samples, unfortunately the samples will also interact with your system so a good set of headphones and quality DAC will come in handy. All these amplifiers are amazing. The tube bjt amp(pathos) sounds good. The class D amplifier sounds good too. The Pass labs is in the top four performers and sounds clean but is almost robbed off that musicality by the class A mosfet outputs and sounds slightly unhinged in the bass due to factors discussed here https://www.diyaudio.com/community/threads/chatgpt-ideas-about-amplifier-design.394541/post-7243081, you can actually pick out the other amplifier that sounds identical to the Pass labs. All these comments are tied to equipment such as dac/preamp and room treatment. So what's good enough for an audiophile?
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Hi to all.

Here is Raspberry Pi 4b + Hifiberry DAC2 HD hat and Moode Audio Player 8.2.2.

Sorry guys, I'm a noob.
I'm trying to figure out what to select (Moode settings) in the "Named I2S device" option's drop-down menu and in "or DT overlay" option's drop-down menu since for both there is no reference to (Hifiberry) DAC2 HD (why is it not present?).

Could someone please help me?

Thanks

I am going to design myself a 3 way center channel. For the design it will have the tweeter over the mid, in the middle with 8" woofers on the sides. The box will be about 9" tall, 30 or so inches wide and as deep as it needs to be for the required volume. My fronts are Swan diy2.2's so I'll probably use a hivi Q1R for the tweeter with it's Fs of 1000htz, I have some flexibility with the crossover point. A planar tweeter would be interesting to use if its possible??, but I don't think it would match my Swan's Q1R. Anyway, given I haven't selected my drivers yet, what are the ideal crossover points for a center channel? Are there ranges of speech where the crossover points should be avoided because it would be distracting? With this information I could choose drivers that fit those specs. These will crossover to my sub at 60htz.
Thanks, Fosmo

(I'm going to keep this a standard schpeel, I hope the Mods don't mind. If so please let me know)
I'll be popping in fairly often. I'm cleaning out and stumbling on things that the community might need.
Certainly not looking to get rich here. Make me a reasonable offer on most of the stuff I unearth and I'll probably take it. Seems a shame to have it in a cardboard box somewhere if it can be used.
Please keep it in the US - I don't really have the time to do paperwork, and i don't want to take the time to research what something might be worth.
So make a reasonable offer - PM Me - remembering it's going to take a few dollars to get it to you. I do appreciate PP F&F.

All of the ON stuff was purchased through reliable sources - after all we are building amplifiers here. Please make an offer on an ettire group and the complements - not individuals.

3X MJL4302A and 3X MJL4281A - make yourself a small AB amp and have a spare set on hand.

5X MJW3281A and 5X MJW1302A - Make yourself a slightly larger AB amp and have a spare set on hand 🙂

3X MJL21193 and 3X MJL21194 - back to making a small AB amp and have a spare set on hand 🙂

5x MJL3281A - for whatever you want to do with 5 transistors

4X Industrial EMI filters, and 2X EMI IEC power entry filters. These are not new. Make offer plus $15 flat rate shipping.

Or Make a reasonable offer on all the ON stull and jam it in a small $10 flat rate box, - this would be nice and easy, wouldn't it

ALL SOLD - Thx🙂

Measure twice, cut once. I want to build horn cabinets for Tannoy HPD coaxial drivers, but "the" GRF plans widely posted online are not as definitive as I had hoped.
I have found these - the simplest:

These - with added fillets to soften the corners (and much larger):


And these - with additional horn length and complexity:


In addition to their design, they are different sizes and intended for different size drivers. The last design specifically says just widen the cabinet to accommodate the 12" vs 10" driver - I did not know you could do it that simply. Does anyone have any first (or second) hand information about these different designs? I have read some reviews of the GRF-R as lacking low bass and being too "boomy" in mid-bass. Perhaps one of these alternative designs can help rectify this issue? Thank you for your input.
-Matt

I have noticed that some amplifiers have thermal paste applied down the entire length of the heat sink.

When reapplying thermal compound after working on an amp is there any benefit to putting it back like original (all the way down the sink), or is it okay to put only under the components 'in contact' with the sink when reassembling?

Hello all
Looking for someone who can fix a pair of JL Audio C3 6.5" component woofers. Or can advise if they are worth fixing. I am in Qld, Au

I got an amp in to check over to make sure everything is ok with it before installing .

The amp is using IRFP3206 as the power supply fets with A1275,C3228 as the drivers .

There are a total of 6 banks of power supply fets in this amp each bank has its own drivers .

I noticed the power supply fets are not all the same date code in 1 bank they have one date code and another bank has a completely different date code . This amp has never been worked on before .

So my question is is this ok to run the amp like this or should all the fets have the same date code and be from the same lot ? There are 3 different date codes

The owner said he didn’t mind if they need to be switched out

The PAM 8403 that I ordered from Ali Express arrived yesterday. Just hooked it up with my Diamond IV for testing. What a nice surprise!

A really serious amplifier, plays loud at 72 dB at 1 metre without distortion, and good bass. No trace of class D metallica. There is that slight mid to high range emptiness, but this was swiftly corrected with a equalizer setting, and this is Bluetooth 4 after all, from my HTC explorer legacy device.

My previous 8403 burned out when I shorted out the speakers terminals I think, so must be careful. A great reference amp. Really nice.

A post from kimmosto on ASR got me thinking about vertical directivity. I am now more convinced that the reason I like my line array more over a wider range of music than any other speakers I have tried is due to the vertical directivity response.

https://www.audiosciencereview.com/forum/index.php?threads/some-help-with-lobing.22661/post-755427

I've done huge vertical directivity, so the last option on the list a coaxial mid tweeter got my interest.

Originally I planned for the coax to sit in between 4 woofers in a symmetric array somewhat like the perlisten tower speakers in layout. Maybe that is what will eventuate but all the interest in Kef speakers and the LS60 got me thinking. Is a Blade like arrangement of woofers a good idea. Having the reaction force of the woofers balanced and placing them close together as a virtual point source sounds good.

The drivers I have are from Sica as they were available at a good price and I have been happy with the build quality for the price on some other drivers of theirs I bought previously.

The 6.5" coaxial was chosen as visual match to the 6.5" woofers and there is something about the response that looks it will be easier to cross together.

A German project using the coaxial is here
https://www.diy-hifi-forum.eu/forum...e-Sica-5-5-und-6-5-Zoll-Coaxe-mit-Kalotten-HT
The woofers here
http://www.donhighend.de/?page_id=5291

I had been 3D modelling ideas in Fusion with inspiration from the TAD Evolution 1 speaker in mind. So this is somewhat of a small love child between that and the Blade.
The name comes from the side shape of the front baffle which is much the same as a Tachi blade.

Looking at ECL84 triode section's datasheet values for mu of 65 & gm of 4000, I want to wonder what single or dual triode (7, 8 or 9 pin) has a similar triode.

I can find plenty of mu = 70 triodes, haven't compared gm yet, because I realize there are several other differences like Pd and voltage limits that prevent direct comparison.

Rather than work in a vacuum (yeah) and draw my own naive conclusions, I thought I'd ask.

Thanks

Hi, not sure if this is a good spot for my question...
But can someone please point me in the right direction.
I have an SPS By Audiovox head unit model (FO-DLX) it only has the 4 positive speaker outputs from the head unit to a factory amp. My question is - Can I, or what would be the proper way to run this HU to a new aftermarket amp as far as the audio ground side is concerned? I found a manual for an older audiovox axt-500 amp that says you don't need to run speaker (neg) when using high level inputs. Is this still a thing today?
Or can I piggy back off the factory amp outputs with some type of LOC or similar device?
I'd really like to keep the factory 2 knob radio and not cut the dash for something that doesn't look good in the interior and didn't want to buy a new retro HU.

Thanks
Dillon

reHello,

I builded the Elliott Sound Project 05 rev D power supply (http://sound-au.com/project05b.htm) with my own PCB
But once I power it up, I got +15V and -21V.
Before the LM317 regulator I got +/-23V.

And I don't find from where the issue is coming. I doubled check the diode and all are OK.

Could some one help to fond out the issue?

Regards

Maximilien

Searching using google.com, the reply is a surprising:

Loudspeakers convert only about 0.25 to 2.5 per cent of the electrical energy supplied to them into acoustic energy.

Click to expand...

Is this true about loadspeakers? What is the efficiency according to audiophiles? It also tells that the DC resistance of voice coils plays a crucial role and is very significant.

This is the equivalent circuit: https://audiojudgement.com/speaker-equivalent-circuit/

Black Friday has spurred a new build. High efficiency coaxial design using with Dayton 12" PCX12-8 and SB Audience ROSSO-34CDN-PK. I will be crossing with a DSP-408.

Now my conundrum is ported or sealed? Either way I will be crossing over above the tuning frequency (have a UM-18 to handle the low end). With being above the tuning frequency does the box have less impact on the frequencies above? Is its not resonant (and out of the Q band) my thoughts are that it might not make a big difference?

I have a pair of B&W DM640i speakers that i've had for many years. When i started having kids the speakers were left in the den which becme the Barney room and they sat there unused for a few years until I finally rebuilt my Living Room.

I just bought a pioneer VSX-1121 and hooked it up just to find that the bass driver on the right speaker is blown. Took it in to a local place (Audio Den) in Lake Grove and am told that B&W does not have the part in stock and there is no ETA on it so it could be months or I might never get it.

Assuming that I just blew most of my non-kid money on the Pioneer receiver, what options do I have to get these fixed? They are a twin bass driver speaker.

Thanks from a Newbie!

$100 for both shipped in the US.

Trying to learn to understand why certain frequencies are hard to get good when building passive crossover filters, and how the baffle size, shape, width and edges create different "problems".

And can i somehow anticipate the response, by building a certain baffleshape?
Or is a certain width and high "always" better for a certain size driver ?

For example:

Ivé build a MTM with 8 inch mids and a AMT tweeter, and have a "irregularity" i like to get better between 600-800 hz.
Sadly i haven´t got a microfone when i had the MTM i the original baffleshape with straight even sides, and after i rebuild the baffle as last picture shows i´ve seems to have hard to get the 6-800 hz "small problem" away.

Any thoughts on baffle and baffels in general ?

Best regards John

LM4781TA Diy audio amplifier kit for sale 26€ more shipment.
LM4781TA with PCB and connector
If you require power supply, the one displayed here can be supplied the cost is 8€ with connector.
Tracked shipment, shipment to US on request
Payment by paypal

Action is a general store found in Netherlands, Belgium, France, Germany, Czechia, Austria and Poland AFAICS. Not sure they stock them everywhere ofcourse.

Not everyone's cup of tea....but I like em.

I have some 6C33C and 6C41C laying around and am itching to build something for them. Initially, I thought about using the 6C33C (single cathode) in a SET amp with a pair of 800:8-ohm transformers I have on the shelf and 6C45-PI as drivers. The amp models very nicely in SPICE, and appears to yield upwards on 10W output.

And then I saw Tim Mellow's OTL... It is an intriguing design. But, I have some concerns about it.

1) Is it safe for my speakers? I know the 6C33C is supposed to be very stable once burned in, but what about at initial turn-on? Won't the output see a hefty DC spike while the 6C33C are waiting to conduct?

2) Can one build the power supply so that heaters are switched on first, and then the high voltage supply is switched on after warming the tubes? Would this be more dangerous for the speakers (by possibly causing the 6C33C to conduct before the bias supply has stabilized)?

I'm sure I'll have more questions...

Thanks!

Can anyone explain me why there is no capacitor between C & B of Q5 just like Q6? I purchased a pair of pcb but before populating it i made a veroboard version for experimentation & i have this question in my mind.

Hello, im new here and i dont know very much about how audio things actually work. I was wonder if i can connect my subwoofer https://mtxaudio.eu/products/rtp12x2/ to my stereo at home https://www.hifiengine.com/manual_library/pioneer/a-303r.shtml (yes its old, but gold). just plug and play with a speaker cable or is that gonna fry everything ?

I'd like to offer up my best version of the Thomas Mayer design 6CB5A tube amplifier. Below you'll see some finished pics and some from the construction.

This is his final (best) version as he started out just designing a cost effective alternative to a 300B amplifier, to prove a point. This he feels is better than most 300B amplifiers and he is not alone 🙂 Point proven!

I invite you to visit Thomas Mayer's web site: Vinyl Savor. Thomas is a long-time, acknowledged, master builder, active on forums and has a business where he sells his finest builds, seemingly most of them custom per customer. This design he generously gave to we who are learning 🙂. My take on this is not a two box design like most of his commercial builds but a three box, power and two channel chassis. I also like a vertical format that allows one to work on the amp while operational to make sure voltages are correct during construction. Three boxes make for better lifting too. I am getting tired of my former all-in-one builds that weigh enough to challenge a man of 60+ years. I even use handles! I went a little over-the-top in using a bridge of all mercury vapor diodes instead of Thomas' more modest blended approach but under testing I liked the sound of all MV and they are SO darn pretty. I have, of course, added switches to warm up the tubes before turning on the B+.

This amp has strength and finesse like no 300B I have been able to get MY hands on (I built two and bought two, sold them all). AND, I have five sets of output tubes for this honey. No breaking the bank when the time comes for more tubes. Others have courted the strengths of this unique tube. Me, I'd love it for the top cap alone! I have FIVE strong tube amps to listen to and that means FOUR of them must go. I am looking at leaving the country in 25 months.

Good news, bad news: the good news is that I know the market is small and I will probably sell it for less than parts cost - that's the good news to the buyer - the bad news is that I really don't want to ship this and I live at the top end of a peninsula (Traverse City, Michigan).

I WILL in fact ship it and I know how to pack it for shipping, but... I predict it will cost $150 and I will NOT be responsible for what the gorillas and fork lifts do. I would really like someone to come up for a nice visit to a beautiful, wonderful, foody, artsy lake city, take in the sights, hear this amp and take it home with them.

AND of course, I have more where that came from.

Parts price on this amp is $800. Come on up and haggle, or not - I always have a good bottle of wine or scotch that needs opening 🙂

Cheers!

Hello,

I work on an old DAC (Parasound DAC 2000) inside which there are a lot of small caps with a yellow color, as shown on the attached photo:



These are small value: 220pF as squared (squared in red color) in the attached schematic, or 0.1µF for the other bypass capacitors.


I would like to know what type of caps there are ? they are probably Film caps, but do you know what type of ?

Thank you very much,

I'm looking at this surround receiver that has a mains switch turn on pop (rocker power switch at the back of the unit) from the subwoofer out. It has several line outs aside from speaker outs. There's no pop from the speakers when turning on.

From the mains switch pop, I measured the sub out and there's no DC spike, but there's AC spike anywhere between 20-60mV.
During standby theres no DC on the outputs, turning on with the front panel switch the sub out has either -20mV or 7mV DC offset. There's a thud and the noise tapers down as the offset drops.

With regards to the mains switch pop, I'm going to replace the X2 mains snubber caps for good measure.
I'm not sure what to do about the pop from turning on from standby. Can't find documentations or adjustments for it.
Anyone could point me in a general direction for this?

Hello all,

I rarely post, but my search-fu has not been able to find an answer to my question. If I install my Raspberry Pi running Moode Audio in my Okto Dac8 Stereo as a streamer, does it remain powered even if the the DAC is turned off, or do I have to shut down the Pi prior to shutting down the DAC?

Thanks for any input/response.

I want to build some Modex Plate style bass traps. I have seen these referred to as VPR or CBA bass traps.

Does anybody have a tested recipe I can follow? I've seen a lot of talk about the general workings but not a build diary with testing.

I'm also not sure how they should be mounted on a wall. Anything touching the steel plate will surely change the modal pattern.

I am looking for a programmable power supply that has very high resolution on the current readback value. Searching the internet, I found this:
https://www.salukitec.com/sps81x-series-programmable-dc-power-supply/

According to the specs, the resolution on the current reading is 0.001 mA, or 1 μA. I asked the company for a quote, and they said it's about $700. That's a lot of money, but much less than what other manufacturers would ask for a programmable PSU with the same current readback resolution.

Is this legit? Any thoughts on the SPS831 unit or the Saluki company in general?

Since integrated linear amplifiers may use a pair of diodes instead of a VBE multiplier, I would like to ask whether anyone had tried successfully using diodes instead of a VBE multiplier to bias a Class AB amplifier built from discrete components. I am thinking of two or more diodes with a high resistance shunt used as a bias voltage trimmer. Diodes have the advantage of becoming shorted in the event of failure as opposed to a VBE transistor which may become open circuited causing the bias voltage to increase to damaging values. I am thinking about using rectifier diodes as bias diodes.

Help is much appreciated.

This tweeter needs service. Who knows the model of this tweeter? It is in use by follow ESS speakers
ESS PS9A speakers pair with air motion transformer tweeters Photo #219772 - Canuck Audio Mart
and
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/8KoAAOSwoydWqRNJ/$_1.JPG
Here pics of the tweeter itself:
http://img.canuckaudiomart.com/uploads/large/86840-ess_heil_ps5a_speakers.jpg
http://bilder.hifi-forum.de/medium/178783/ps8a_244986.jpg
There are no informations under
Heil AMT – ESS Labs., LLC
Maybe it is the predecessor of the AMT-2 - go to
LSV Dieter Achenbach
If I have the model number, I hope to find the instruction manual for disassebmly and reconing.
Thanks for your advices.

For lower level listening, is it better to have inefficient speakers at higher volume or efficient speakers at lower volume?

Hi all,

I have this amp with a shorted output fet. Please advise what parts are to be used as replacements, power supply and output.

Power supply fets are not shorted. Pics attached.

Power supply - H1

Outputs - B2

Hello Admin and members
I would like to request an addition to source and line forum, please. A forum for 'Audio Creation' devices. There are some great forums for Audio production out there, but all these lean heavily on brand names. We have the instruments and amps and the PA forum here, but those are again for the larger scale items like power amps and PA as well as troubleshooting and cloning. Basically that, I am noting that the bulk of the forums represent audio reproduction while more and more music enthusiasts are exploring a variety of home music creation setups with the modern range of electronic and computer based tools and instruments

It would be great to have somewhere to discus and evolve DIY music creation tools and devices. Both hardware and software. Things like shop and DIY synths and digital mixers and controllers, monitors as well as the usual DIY shenanigans with upgrading and customising. I really feel we are missing this to fully cover our scope of interests


I have a self-interest in this. Today I am starting a home renovation. I am semi retired and moved into a "tiny home" in sunny QLD with my wife and daughter. We are now expecting another child. It's just been too hot to work in the shed, so I am bringing a part of my workshop inside into the studio area, which is also the main bedroom. It will be awesome to have somewhere to log and request to assist with the challenges of child safety, challenges of audio production and reproduction with limited spaces and such

Another example of self-interest would be, in planning for the renovation, I have been acquiring both production and reproduction hardware. I have now all the mixers and controllers and such here and space planned out. I want to add a stand alone virtual synth based on an Android PC. Will be awesome to have the place to discuss the evolution of this too

The source and line forum would be perfect for this as it is another facet of audio manipulated around line level

Guys, please back me up if you see the merit

Thanks and regards
Randy

I've got an application in mind for an NPN bipolar, running about 10mA, at low VCE. Imagine a cascoded current source or a full 4T Wilson mirror, that sort of thing. I'd prefer to avoid transistors that exhibit Quasi Saturation at 10mA, because their effective ro (=Vearly/Ice) is poor.

So I decided to measure a few transistors. Here are the results. The ones that my eyeball says "Yes, that looks like Quasi Saturation to me!!" are marked with red arrowheads.

Surprisingly, a few Author Favorite transistors seem to Quasi Saturate at 10mA:

• Bob Cordell's preferred 2N5551: yes it Quasi Saturates.
• Douglas Self's 2SC2240BL and MPSA42: both Quasi Saturate.
• Samuel Groner's MPSA18 (and 2SC2240BL): both Quasi Saturate.

I don't mean to suggest that these fine gentlemen have made a mistake; rather, I'm just pointing out that when I run their favorite transistors at 10mA, the measured IV curves are a bit ugly. Perhaps these honorable fellows would never in ten million years recommend operating these devices at 10mA. I bet that in the future, they certainly do not.

Hi everyone,
I am looking for a place to buy BBE-style dual-channel ICs with per-channel control like the XR1075, but I can only find it pre-mounted to processing boards, which I do not want. Does anyone know where I can get these? I have been using two CoolAudio V2153s on one PCB but it makes the schematic needlessly complicated and redundant. Thank you.

Has anyone tried out this processor?

Just wondering if the Beyma 15LX60v2 would be able to used for a 2 way system? I have a 600Hz horn that I plan on using for the HF.

Anyone had any direct experience with this driver and if so what would be the HF limit of it?

Is there another driver that would work better? i.e. I like the 15PR400 but I am concerned about its limited xmax. Also the 15LX60v2 looks like it would work in a smaller enclosure.

Thanks in advance

Richard

Hi. Does anyone have a copy of the schematic for the Parasound Zamp version 1 handy?

Thanks in advance
Mayank

Hi,
anyone has Mackie MR624 II schematic/service manual. ?
thanks and regards.

Hi guys,
Just curious if there's any performance gains. Putting aside cost is there any advantage of using 4 trafo with 1 secondary each feeding say 4 supplies vs 1 trafo with 4 secondaries feeding the 4 supplies.

Thks

Hi guys,

I opened an amp with heavily burned power resistors.
The board itself was burned as well.
I expected it to be the VCC supply of the opamps in the filter section, but I don't read strange numbers there.

Does anyone know how much the resistor value should be? Since they are all discoloured?

Not sure if there is a build log area, but here goes.

Driver: Rockville RVW1800P8
https://www.amazon.com/Rockville-RVW1800P8-Subwoofer-Woofer-Magnet/dp/B01DP0HKJK?th=1

AMP: GetSHOW 2400W Plate Amplifier with DSP: https://www.aliexpress.com/item/400...o.order_list.order_list_main.5.648c1802L916aM

(If it turns out its not as powerful as I expect, I will likely make it a passive speaker cabinet for now. I think plate amps are hard to gauge, if that is the case I will likely use a Crown amplifier instead. I based the enclosure loosely on the design here: https://www.loudspeakersplus.com/Articles.asp?ID=258

The enclosure is built to also accept other 18 inch drivers, mainly because I wanted to ensure I could actually figure out how to build a decent one before splurging on the RCF drivers I originally wanted. (RCF LF18X401)

Tomorrow after the original glue up for the front element is dry, I will start to assemble the box and put in the bracing. Stay tuned!

Build itself:
Attached is the cut list, with the final dimensions being 780x580x650. Port area is 540cm2 or 10x54cm.

The debt of the port is 37cm, or 34 internal. I could have made this slightly longer for a expected resonance of 35hz, but I think this is fine.

Its made to accept a much more powerful speaker, upwards of 1500w and 125 dB @ 1m (Calculated). I will make two of these to replace some old ELX200's that's disappointed me multiple times..

Besides the cutlist, I used a local sawmill, you also need to cut the baffle at 544 x 37 and a small support at 37x10 cm.


Handles? I will be purchasing some from Adam hall, and a speaker-con connector plate.

Hi all,

I've read multiple threads on the subject and I'm getting a bit frustrated 🙂 Before calculating my own box I wanted to 'benchmark' by simulating the cab designs available on the website in WINISD. I don't get why, simulated before with dayton and other drivers, which I built and measured as expected.

I followed the tips on how to input a driver, basically not entering all data but having WINISD calculate as much as possible to avoid rounding errors. I got a 'green message' approving my driver in Winisd which is good. I tried also the export file available at loudspeakerdatabase, but it keeps calculating differently from the cab design sheet, I keep on getting a negative port length. I must be doing something wrong, and getting a bit frustrated.

Strange things is, I do get a vent speed similar (but higher, but that's because i used a round port as most topics say winisd does not calculate rectangular ports correctly) to the simulation. Also the graphs look similar, except the DB are much higher. Also the cone excursion at 600W is completely off.

I've done dozens of simulations, changed the parameters, so I will probably be doing something very wrong, would love to get your help on this! Avoids me building total crap with this driver.

How did u get into the world of repairing amplifiers?

PA150 LM3886 pcb with all components to complete less the audio input capacitor "68€ more shipment"
IC's are new and are not applied on the pcb,like main capacitors,power connectors and SMD output resistors
the other components are already assembled, with genuine components,like on the second picture.
Machined Heatsink with the machined copper hardware and ceramic pads can be supplied the cost is 78€.
DRV134 and gold plated pcb can be supplied if requested cost is 16€
I have also power supply pcb's for who want one model the power supply can be used for powers up to 400watt
and the other for powers up to 800watt, power supply partial assembled as example.
Tracked shipment, shipment to US on request.
Payment by paypal