So if horn A has a mouth that is 1 meter wide and has horizontal coverage of 40 degrees...

And if horn B mouth is 25 cm wide and has 80 degrees of horizontal coverage...

Which horn has wider coverage in reality at the listening spot?

Is the dispersion pattern measured from the driver or from the horn mouth?

Do smaller horns have more narrow dispersion in reality because of the smaller mouth size?

Hello all,

Most that know guitar amps know that the JC-120 is THE BEST CLEAN AMP EVER - and the best Solid State Guitar amp in existence. These amps are found in all types of music - Jazz, rock and roll, metal, etc (Police - Andy Sommers, Metalica, etc)

Anyway, I downloaded the schematic (the version with 2SK117 not the later opamp version) and had a PCB fabbed with the help of a fellow DIYAudio member (Thanks Craigtone!!)

So the preamp has all the goodies including a quad of 2SK170 instead of the 2SK-117 (a deluxe version?) and behind it is a LM3886 - standard fab of Brian Bell's gainclone amp. Preamp has volume, bass, mids, treble and a Hi Treble switch. With LM3886. it's roughly 45 wpc. No reverb, chorus, etc, just the preamp / amp section. The rest you can do with pedals.

After building the amp/preamp, I bought a real Roland JC-120 Guitar amp, and surprisingly sounds very close. Bandmates were impressed!

Selling as I built another in a nicer case and it has a 200 watt/channel ICEPower 200ASC behind the JC-120 preamp.

Amp $150 + ship

Also have a few PCBs if anyone wants one - free you pay ship and you make a donation to DIYAudio site would be great.

Pics on the way...

Hi everyone
My friend have an Pioneer A-717 amp , he matched with Wardafle Diamond 12.4 speakers, so when he put the second speaker there was no sound we saw fumes coming out of the amp , It looks like the bare ends of wire shorted Spk+ with-

So I opened it up , I saw 2 pairs of one channel Transistors measuring short (2SA1265+2SC3182) , and cermaic resistors measure open (RGC55) , and two resisotrs in the block 47ohm and 260ohm were open , so I didn't had the same Transistor pair ,, I used 2SA2151+C6011 pair which has more power handling capacity, however lesser transition frequency of 20Mhz ,compared to orginal which is 30Mhz is that a concern , ? Is it suitable ?

Actually , I did replaced and power on , but I didn't get audio although I replaced Resisotrs, then I find one of the diode surrounding PA0016 IC measuring low resistance of 135ohms in both directions, which is not the measurement in the other working channel , when I Desolder IC PA0016 the short is gone and the IC measures low resistance like 32ohm and 57ohm in the adjacent pins , I feel the IC is shorted , Im thinking of swapping IC from working channel however before that I wanted to confirm that the newly repalced equivalent Transistors will cause any harm to IC PA0016 ?

(sorry for the long post , )

Hello!

I am adding a 'raised ground' to one of my power amps, a relatively common circuit that is simply a capacitor, 10R resistor and bridge rectifier in parallel. You can see it described on page 15 of this excerpt from The Valve Wizard's preamp book.

One curiosity for me is the 6A current rating that he suggests for the bridge rectifier. This seems like a helluva lot for something that is designed to blow a fuse under fault conditions! Most BR are rated for relatively high surge current, which seems like the more appropriate rating to looking at, rather than continuous forward current.

Should I just pay attention to the surge current rating when spec'ing a BR for this circuit in my own amp?

Thanks in advance for any help 🙂

https://item.taobao.com/item.htm?spm=a1z09.2.0.0.27d62e8dnvmGGx&id=643128215193&_u=b20esclga3d01d

Scan Speak D2905/95000 selling for 28EUR/pcs when it's ~140EUR/pcs in Europe DIY stores. Still a deal if we even count customs taxes and delivery through third-party shipping service to EU.

Maybe someone from China DIY community members can comment - are there any issues with product quality of these cheap branded drivers from taobao?

Hello,

I'm a residential architect that has decided to rekindle my interest in high quality sound. As many architects do, I am venturing out into product design and am in the process of creating my own custom speaker enclosure. As I dive into this project, I realize I have a lot to learn and look forward to connecting with this community. My goal is to create the best speaker enclosure within my tool set of capabilities using the best components within my budget. Looking forward to the journey and the iterations along the way.

Look on https://delax777mechanics.com/

Hi all,

My name is Plamen, and I’m from Bulgaria. I’m new to the world of audio electronics, and this is my first attempt at solving such a technical challenge. I’m currently working on a project to enhance the audio output for headphones. My setup involves a Type-C to 3.5 mm jack audio adapter connected to an Android device. The issue I’m facing is that the chip in the adapter doesn’t supply enough power to properly drive the headphones, leading to very low audio volume, even when set to maximum.

I’ve tested this setup with various headphone models, including the OMWCO1, and encountered similar problems across the board. Interestingly, swapping headphones sometimes results in interruptions and strange crackling noises. I’ve also experimented with an Xmart-branded audio adapter, dismantling it in an effort to identify the chip used inside so I could order a replacement or find a more powerful alternative from electronics suppliers. Unfortunately, I haven’t had much luck so far.

I’m looking for an external chip to act as a headphone amplifier that meets the following requirements:

• Provides sufficient amplification for clear, powerful sound.
• Maintains compatibility with Android devices via USB Type-C.
• Operates efficiently without excessive heat generation or high power consumption.

If anyone has suggestions for specific amplifier chips, resources, or general advice for a beginner, I’d be incredibly grateful. This has been a challenging but exciting journey, and I’m eager to learn more and resolve this issue.

Thank you for your help!

Hi there.
My name is Terje Berg, from Norway. I am into DIY Hifi and are now trying to learn more about horn/waveguides.
I have made a JBL DD66000 and DD67000 clones in my past that was kind of successful. (From OEM raw cabinets)

Link to the local HIFI forum where is documented the process here: https://www.hifisentralen.no/forumet/threads/terjes-wall-of-sound.62948/page-6

Hi all. I completed build of V1.8 a few weeks ago. The amp seems to be performing fine (operating one in stereo mode) but in reviewing pics others have posted I now realize I incorrectly followed wiring instructions for V1.6. As long as I operate in stereo mode is it still safe to use until a get around to correcting the back panel wiring for the 3 way switch? Thanks

I'm not sure if anyone is familiar with Gavitt shielded wire. I'm old enough to remember seeing it in audio equipment, both professional and consumer. It is a braided shielded type with no outer covering, the braided shielding is exposed. The inner conductor has cloth insulation and is tinned. I'm doing an amplifier build and bought a length of the wire. The combination of braided shield, cloth insulation and tinned inner conductor helps the wire hold its shape. The absence of insulation over the braided shield probably also helps. The cons of using this type of shielded wire is the extra time and work involved. I usually only connect shields at one end of a shielded wire. However, the braided shield needs to be unbraided at both ends. I used a sewing needle to pull the braid loose. This is time consuming and one has to be careful not to damage the inner conductor cloth insulation. I used shrink tubing at the end of the braid, also over the end of the cloth insulation to prevent the insulation from fraying.

The amplifier is a two channel (stereo) Class A ultra-linear using a single output tube. Output tubes are 6L6GC or KT66. I will also try 6CA7s. The power transformer has sufficient rating to handle the extra filament current. The rectifier is a 5U4. There are three stereo inputs, each input has its own level control. Over the years, I have found input selector switches to be troublesome with dirty or worn out contacts. The other controls are balance plus low and high adjust tone controls. My listening area is small, I don't need a lot of power. I have also found that, to me, Class A operation produces a more pleasing sound than push-pull.

Folks:

I am considering hosting a group buy for pairs of Aikido Noval pcbs (kudos to John Broskie's brilliant design and the generosity of Sadface). This group buy would be limited to members in North America; members outside of North America are encouraged to buy the Noval boards directly from a fab house.

Expressions of interest in this opportunity should be directed to the originating Aikido Noval thread -- see Post #34 at https://www.diyaudio.com/community/...b-or-gerber-source.419429/page-2#post-7842704

Regards,
Scott

Hi! I am selling 6x LM4780TA, 10 pcbs for LM4780TA and 1 pcb for power supply.
All the ICs are originals.
The pcb is a stereo design and can also be configured as a single channel parallel amplifier.
Board Dimension : 144mm x 64mm. Thickness : 2mm. The PCB uses 70um thick copper ( 4 times normal thickness) and is gold plated.
Prices:
LM4780TA - 20 euro/piece
Amplifier board - 5 euro/piece
Power supply board - free for the first one who buys LM4780 + amplifier pcb
I ship only in EU, the shipping cost is 15 euro. Thank you!

Hello everyone!
I've been following the community for a long time, but I wasn't a member, and that's the end
it changed)))

I want to thank Nelson Pass for his great schematics and I also want to thank Prasi for his PCBs. I have almost finished assembling the AB100 and have even enjoyed its sound. Thank you all again.

PS: I apologize for my English, I'm from Ukraine.

Which one would you go for, in these close to identical circuits? One with LL autoformer and the other with an AC-coupled 1:1+1 transformer. I am only interested in AC-coupling, ie no DC through the primary. Not sure of LL transformer to choose, capable of handling the high signal voltage? Circuit will work between 300Hz and 4kHz.

I have noticed quite a few questions about the suitability of the store's
heat sinks for various projects, and since I have tested and documented
most of them here, I am happy to present my list of the sinks and their
respective thermal resistance numbers. Toward the bottom it lists the
wattage for a 30 deg C rise on a single side and the number of TO3-P
type packages it is drilled for.

Hi all!

My name is Walter and I'm from the Netherlands. I'm interested in DIY audio projects and hope to find answers to my questions here on diyAudio.

Amp is SST Son of Ampzilla by Bongiorno, not the latter all-new amp w/the same name and "II" suffix by Wyred4Sound/EJ Sarmento. Rated 100/200/400W @ 8/4/2-ohms, single 1k VA toroidal transformer, 100k uF PS filter, 55# net, a serious piece of kit by a person credited with creating the ubiquitous balanced differential circuit.

Can readers predict (say, within a range) the dB difference between using one SOA/Bongiorno in stereo vs. two SOA, one SOA p/c and one channel per each amp? One professional suggested 6 dB difference obviously favoring the latter, which sounds high to me.

I have a huge selection of power Rs. I have only one SOA. I considered listening to one channel of one SOA > one speaker channel and assembling a big bank of power Rs for the other unused channel, comparing the Rs to no Rs/no load. The speaker is 4-ohms nominal with a reasonable EPDR. If this is a good idea, please define the recommended R load and minimum power.

Thanks.

Dear all,

After some time I am again in DIY area, so I have (perhaps stupid) question...
I have two sparate PSU from HP, I think from some printers or scanners. Model 0957-2260, output voltage is DC 32V and output current 5625 mA, what is OK for my application. Of course, I need two of them to have symetric power supply +32 -GND- - 32V.

Question is: is it possible to connect theirs outputs to achive desired voltage or not? It means that I have to connect plus from one to a minus of another one to have central point.

Something rings in my head that someone told me that I need to do something with input connection (230VAC), but cannot remember what was warning...

Any ideas, advices?

Thank you in advance, regards,

Boris

Hi,

First post so be gentle..

I've been meaning to join this forum for a while as I almost always end up coming across great information from here. I started my interest/vocation with electronics with audio and moved onto digital/power, well, its about time I got back into the swing of analogue audio design.

My first question is about repairing a Rel Storm III sub for a neighbour. It's an older 2002 model, and by the looks of things the bipolar driver transistors for the MOSFET have blown, taking a resistor with it. After contacting Sumiko about it, I managed to convince customer support to provide the value of he burnt resistor, and I have the datasheets for the driver transistors. (BFN16 NPN, and BFN19 for PNP). As these transistors are SMT SOT89 they can't dissipate much heat, which is probably why they have failed (even with a good copper heatsink on the PCB). They added through-hole footprints on the PCB in parallel, making it easier to use TO-220's (or TO-126) for replacements, so I was thinking, MJE340's and 350's?

I am not after 'improving' sound for my neighbour as he is happy with it, so the closer I get to BFN16/19 equivilents the better, and being a sub, high end frequency response is not an issue. I picked these transistors for availability, and their higher power dissipation, along with the possibilty of adding a heatsink.

There's also the MJE15034/35, which are most expensive, higher gain, greater power dissiaption, highg frequency response etc.. but I fear the high end won't be needed for a sub, plus, perhaps the higher gain would result in a change in sound, or require a change in the values of passives.

As cheeky as this is, if anyone owns a storm III, any cance you could post a pic of the power amp PCB? Specifically the driver transistors not the MOSFET's). I read that Rel upgraded the design in 2005 due to failures (most likely of this kind) so a picture of the later model would be ideal, as I could see any changes they made. As you can guess, Rel is understandably a bit hush hush on this, as they want money for repairs, plus, its a specialists field, for qualified 'rel engineers' only.

Ultimately, despite my (somewhat limited) understanding of audio electronics, I am not trying to reinvent the wheel. Purely to get the sub working again, as close to the original sound quality as posible, but improving reliability so parts don't overheat again. Hopefully he can enjoy another 10 years of it, without having to upgrade 🙂

Cheers,

Buriedcode

Hello! Having a great time designing and building my own audio equipment!

Been working on a stereo PCB based on the Project 3A from Rod Elliot, i'm here asking you guys what do you think about this layout.
P.S. Since i can't find the exact BJTs used in the original Project, i wonder if i could use a couple of 2SC5200 and 2SA193.

I run sound at a local skating rink that has a 10,000 square foot oval skating floor that is coated concrete. Has walls on three sides with one long side open to the rest of the building.

We currently have four Yorkville 18" subs (two at one end of the rink two at the other end of the rink) which never sounded good.

We replaced three of the 14 QSC 8" two way powered speakers (only three of them actually still worked) with three of the Mackie 212 powered speaker.

Decided to look up subs and found the Rockville RBG18FA as I'm looking for the ability to reproduce bass under 40Hz and the Frequency Response spec is +/-3dB 25Hz - 120Hz which should fit the bill quite nicely.

https://www.rockvilleaudio.com/rbg18fa/

Would that be a good sub for the application and if so how many are needed and where should they be placed?

If that is not a good sub, what sub would be recommended for about $1,000 or under?

The system gets turned up a good bit once a week for four hours continuous by a local DJ who plays there.

My SMPS1200A180 (v7) (feeding a 4-channel UcD180-based amplifier) was taking progressively longer and longer time to start. Over a year or so it gradually went from seconds to minutes from the moment the power was supplied to the relay click and the actual start of the amplifiers. Today it just refused to power up. The internal fuse is fine. Disconnecting the amplifiers makes no difference.

Anyone with a similar experience? Any suggestions on the repairs? Thank you!

I've got a DBX 234XS crossover which I use in my home stereo using XLR to RCA cables I made and XLR to 1/4" balanced to connect to the USB audio interface.

Anyways when I turn off power to the power strip everything is plugged into, there is a nice pop in my speakers.

Is it normal for the 234XS to cause that sort of pop and if so can it be fixed, or does it have a problem?

Also, if it is normal and no fix can be done, what is a decent 2 way 24 dB/octave active crossover that does not produce any pop in the speakers?

Hello forum, I'm thinking of building this but using rimlock complement (EF40, ECC40, EL41/2, EZ40) just for fun I did this exact version once with very good results and since I have the valves and sockets thought of putting them into something "useful"
I know EF40 is EF86 equivalent and the pentode section of the ECL86 is almost the same as the EL41

My question is what would I need modify to fit the ECC40, accordingly to Philips the cathode and overall bias has to be changed (of course it is a completely different tube)



So, do you agree with Philips recommendation ? any comments will be appreciated.

Greetings from Dallas, TX.

I bought a pair of these from a guy who does new cinema sound installs and selling the old systems.

Link for reference is here: https://eaw.com/documentation/cb152x/



Would anyone know what model of woofer is used there? It looks like a BC 15", since one of the HF drivers is BC DE72. I took it out, bit there is no label (OEM by BC?)

I might try to take it out and make pictures, but it looks as many other 15" woofers if no one knows the replacement given by EAW. The one I took out already had its part number unreadable, will have to try the other one.

Hi all! My name is Nick and I live in San Diego.

I am an audio enthusiast and my current setup consists of:

Sources:
Luxman PD-151 Mk II turntable/Gold Note PH-1000 Lite
Gustard A26 Dac

Preamp/Amp:
BAT VK-80/Accuphase P-360 (just upgraded)

Speakers:
Scansonic MB3.5B

I use Roon and HQPlayer for streaming with both running on a Mac Mini M1 and the HQP NAA running on a RPi5.

I am interested in a DSC2 DSD dac to replace the Gustard since I prefer to let HQP convert everything to DSD.

Thanks for reading - Nick

Brand New in boxes.
These have been sitting in my cupboard for 10 years for unfinished Boominator project. Selling to rationalise my extensive project list.

• (4x) P.Audio SN-10MB MkII 600Watt 10" Low Mid Frequency Woofer
• (4x) P.Audio PHT-407N 1 Inch Horn Loaded Super Tweeter Neodymium Driver/Horn Combination

$1000 for the lot.

https://audioxpress.com/news/the-return-of-an-icon-the-new-revox-b77-mk-iii-tape-recorder



dave

Hi folks. Long story but keeping it short. I have a CA5300 that was blowing fuses. I took it to repair and see my luck. Figured out that one channel's amp board had all the outputs shorted. Below is summary

CH1 - While amp was off, I didnt realize that wired from PS still had 80+ volts and it sparked. I then discharged the caps and then connected it. I then noticed the 253 transistor was chipped off. No burn smell through. I replaced it from other board. Swapped this from other board and when I switched it on a loud bang and before any smoke, I immediately switched it off. With these amps there is no way I can use a DLB or Variac as the protection circuit doesnt engage if it sees that I have a DLB (100V bulb) or a variac.

CH2 - I powered it on but had the magic smoke. Later I see there is a 82V zenar doide and adjacent 253 transistor was smoked. I used parts from this board to CH1 and waiting for the parts to arrive.

CH3 - Working fine

CH4 - This was the original channel that had blown outputs. So I swapped the A1294/C3263 pair of outputs. Total of 5 pairs. This time, I used all the outputs from CH2 and the amp started to work and thought I had fixed it. The sound was not fully clear when I was testing. I increased the volume and boom. went into protection mode and same original issue. It was blowing fuses. All 5 pairs of outputs went shorted within 2 mins of running. This also caused the two big CL80 thremosister (maybe a bigger one not sure) to smoke but I switched the unit off on time.

CH 5- Working fine.

I checked all the caps. For each board there are 9 of 100uf 100v. They all are measuring 89 to 92uf with .45 ohm ESR. I will be changing all the caps and will see. For the people who worked on these amps, what were the probable components that failed. The LME49810 is unobtainable and I don't know how to check if the chip is working or not. I am trying to source 10 pairs of A1294/C3263 and K-amps member was kind enough to confirm that he might have them.

So key question is what would be the cause for the pop/bang from amp board and smoke. Even if I manage to find 10 pairs, how do I validate if the amp board would work without burning any components. Any guidance that helps me. Thanks

Hello everyone

I have been gone for some time. I know there are many threads on this boards and i have them open but I have. few particuklar questions for this build and it would be very helpful to. me if i could document the progress here with p[ictures and ask my questions and hopefully get some tips and guidance.

I have these parts:
Login to view embedded media
my first question is about powering the board with +-15 VDC
would it be possible/advisable to power it with one external 15VDC power supply? i wire in the positive polarity for the +15 and i swap the positive and negative for -15
in this way i am only using one power supply and the two voltages will be mirror images so if one has a +0.03v ripple the other will have the exact voltage in opposite plarity and the two channels will have truly mirror coltages applied to them at every instant. is that electrically ok?

Hi all, I have been replacing old passive components from a tube amp and have seen that people think a polypropylene cap is better than a polyester cap and was seeing if you thought it was a good idea to replace them. They are 0.047uf 250v. I’ve included a pic of a cap that I plan on replacing and a photo of replacement. Also is there a better replacement for this polyester cap?
Thanks in advance
Matt

I've started a layout design on the Rod Elliott's Project 10, i'm seeking for you advices.

Hi!

I've built a couple of kits before, but I've just started designing and building a speaker from scratch. I’m cheating a bit though. Ganesha, my speaker, will use the same drivers and have roughly the same volume as the open-source SB Acoustics Bromo kit. So, it wouldn’t surprise me if I end up with similar port dimensions and a comparable crossover.

I've just glued up the cabinet and started to learn how to measure drivers... and I'm a bit lost so thats why I'm here. 🙂

Cheers,
Jan

I have been testing a pile of JFETs (multiple different part numbers) with multiple different instruments to find a simple DIY method for creating matches for some JFET Beast PCB builds.

I believe that matching can be accomplished simply and at a very low cost. This thread is to show my conclusion of a rig to measure each JFET.

The journey to get to this point is a discussion for another time.

The pTA consists of a connected pair of OTA's to simplify balanced input/output functions, wanting to avoid the matching of numbers of precision resistors without resorting to INA's necessarily. It takes advantage of the formidable current mirroring (shown below on the right) and the CMRR already existing in AD844 devices, adding a linearization input network using an NE5532 dual VFA op-amp. Although this pTA cannot match the minimalist distortions or CMRR capabilities of the best INA's it does an excellent job IMO without using global feedback, producing a pair of differential phase aligned output currents.

The pTA supports differential input signalling, allowing for a broad range of applications left to the imagination of anyone here to use. The NE5532 input device bypasses the non-linear transconductance of the input buffers in each of the AD844 CFA's. In so doing the pTA has much lower distortion and can generate programmable currents using a single resistor, in this case R6, in a simple calculation using Ohm's law in relation to the differential input voltage.

As this current is channeled to flow only into (or out of) the inverting terminals of opposing AD844's, the currents are equal in feeding into their respective current mirrors, being also complementary matched in the folding over with AC, a condition that generates equal amplitude differential currents phase aligned over wide frequencies. Phase alignment is of advantage in the process of converting back from differentials to single ended at the receiving end.

A basic implementation of the pTA is shown in the LTSpice screenshot below. The voltage outputs shown on the right are labelled on top, this corresponds to nodes identified on the schematic, being also colour coded to the waveforms below the labels.



In this simple example a 1 kHz 2 Volt pk/pk signal is presented from a floating source B2 that looks into a 50 kOhm load, being arbitrarily offset by 4 volts DC. The ends feed into U3 and U4 via lines N001 and N006. These appear as red and grey waveforms centered around +4 V DC. The two output signals in yellow and blue are centered around zero volts, being produced by U1 and U2 on nodes N004 and N008 respectively. The output signal voltages can easily be calculated with reference to the input Vin differential signal whereupon for the yellow sine trace has Vo = Vin(diff) x (R11/R6) or 3/4 Vin and the bottom Vo = Vin(diff) x (R2/R6) or Vo= Vin. As can be seen on the schematic the extent the 4 Volt DC is stripped from the output signal is down to 4 or 5 milliVolts, this is close to about -60dB CMRR. To obtain similar results from a resistor based network seems would require resistor tolerances in the order of 0.1%.

I would like to thank Hans Polak for his assistance in reviewing this material, for conducting simulation experiments on distortion and for assisting in the learning and using of LTSpice. I hope that the material presented is of use to anyone wanting to experiment with it... and hope that the results are shared...forget it if its negative though...quiet...no I won't!...I'm warning you...make my day punk!...stop it... people with start to think I'm crazy... I know I do...

Hi everyone!
My name is Daniel and I'm from Norway. I've recently gotten into the world of audio and found a lot of valuable information on this forum and I'm very excited to learn more!

I have finally acquired a Counterpoint SA-11 preamplifier! It does not pass a signal except through the passive output. I am hoping someone can help me with documentation. A manual for adjusting the various potentiometers and a schematic would be wonderful. If you PM me, I'll send my email. Thank you very much!

I just made myself a high voltage regulator that I could use for my tube experiments. If you also need a high voltage regulator with good performance, or want to make use of the jellybean parts around, here's a design that is fully simulated and tested.

Features

• Ripple rejection measured at least 93dB (limited by apparatus)
• Output noise measured at most 50μVrms
• Using TL431 as voltage reference and LM317 as pass transistor
• Ability to add soft start function
• No bulky film capacitor needed (if a bit higher noise floor can be tolerated, so the PCB could be made smaller than a credit card!)

Yes, I know there's the 21st Century Maida Regulator, which is very applicable and I even built one myself. But after intense experiment I'd like to share some ways you can tune a regulator better or more suitable to your case. Perhaps I could call this regulator the 2020s Maida Regulator 😉.

Schematic


The good thing about LM317 is that it's available, reliable, and doesn't require a big output capacitor to be stable. However, the original Maida regulator suffers from poor ripple rejection because of greatly reduced loop gain especially at low frequencies, and the additional 6.9V zener doesn't help much. I found there was a mysterious 1.5Hz voltage fluctuation on my mains and the Maida regulator was almost helpless. (In fact I even tried a 100V zener. It did help a little, but for greatly increased noise and temperature coefficient.)

A TL431 driving LM317 is always seen as a form of super regulator: it has very high ripple rejection, at least IN THEORY. My regulator uses the same idea but adds protection to every low voltage part so they can regulate a higher voltage. (Q1 protects U1, Q2 protects U2, Q3 protects U3) For details of the components see the following sections.

Measurements

I tested the prototype PCB using my DIY low noise preamplifier whose input noise density is only 1.4nV/√Hz and bandwidth 0.1Hz~100kHz. (with a 10Hz HPF for the following measurements, image 02 below) All measurements use a 10kΩ load at the output unless specified. The output voltage is 451V, which is a bit off from the theoretical 2.495V/1.8k*(1.8k+330k)=460V because I used 5% resistors. However the voltage reading doesn't change when load changes to 3.3kΩ (136mA).

When C1 is 3.8μF of ceramic capacitors, the output noise is 70μVrms. When C1 is a 4.7μF film capacitor, the output noise is 50μVrms. The image 01 shows the noise waveform 1000x amplified.

According to the SPICE simulation with the most accurate 431 and 317 model I can find, PSRR reaches 160dB and the output ripple shouldn't exceed 100nVrms. (buried in noise) Reality is mostly disappointing. With an input ripple of 1.8Vrms, the output ripple measured by averaging is 40uVrms which means PSRR=93dB. However my preamp shielding isn't particularly clean and the output might have been polluted by the mains, because measuring the LT3080 version also gives around 45uVrms, which means the majority of output ripple might be mains hum coupled into the scope somewhere. Try measuring it better by yourself to determine the actual PSRR value.

Components

I assembled the prototype board with mainly SMD parts, and ignoring the unused area (which I planned for testing some other circuits) the actual size is smaller than a card. You can use THT parts of course. Here's a list of explanation for some components:

Q2: Power MOSFET used as cascoded U2 protector. I just happened to have STW11NK90Z in hand, but beefier STW12NK95 or lighter STW8NK80Z should also work.
U1: Original Maida regulator uses a Zener diode, but I found using a TL431 gives lower output noise. TL431 has another benefit which is its low output impedance compared to a Zener. This impedance acting with the Ciss of Q2 can create an unwanted pole in the cascode loop, and may cause parasitic oscillation. See Q1.
Q1: Providing bias current to U1, and isolates the Ciss of Q2 from U1. TL431 typically can only take up to 1nF (for small capacitance) from its cathode, so Q1 also acts as a buffer between U1 and the gate capacitance larger than 1nF. Also if you:

• use a resistor instead of Q1, or
• use two LND150 in series instead of CPC3980, or
• connect Q2's gate to the bottom side of R3 (suggested by The AoE Figure 9.113. To be fair they added a ferrite at the gate.)

then using a 0.5W 15V zener to drive STW11NK90Z will certainly result in oscillation and the HV transformer will shout. Interestingly, 1W zener driving STW11NK90Z (Ciss=3nF) or 0.5W zener driving STW8NK80Z (Ciss=1.32nF) is stable. Meanwhile, I highly suggest that you DO NOT include a gate stopper resistor for Q2, as it also slows Q2 down and WILL cause oscillation. These observations are highly component-dependent and I don't know if your parts will behave the same.
U3: Voltage reference and feedback amplifier. This TL431 is protected by Q3, D1, and D4. However, TL431s from different manufacturers might behave differently. See R10.
Q3: U3 protector by cascoding. I have some LND150 in hand but an enhancement MOSFET with enough voltage rating (like over 600V) should also work. If using an enhancement MOSFET, prepare another bias voltage of around 10 to 15 volts for the gate.
R4: Decrease the thermal dissipation of Q3. If you change the output voltage to be lower this is optional.
R8, R9: Feedback resistor determines the output voltage. Output voltage is 2.495V/R9*(R9+R8)
C1: Adj bypass capacitor for LM317. Can be as low as 0.22uF but the larger C1 is, the lower output noise will be. If C1 is larger than 4.7uF, during start up the output voltage will ramp up for extented period of time. This acts as a soft start. Capacitor larger than 10uF doesn't affect the output noise more but still extends the soft start. C1 also contributes to the loop stability, see R10.
C2: Used for increasing HF loop gain around U3. Maybe be optional but adding it improves PSRR and lowers noise. 0.22uF MLCC is generally enough.
R10: Tunes the HF loop gain. If C1 is larger than around 1.5uF and U3 is a TI or HTC one, then R10 can be 0Ω (shorted). If C1 is smaller, then R10 has to be made larger to ensure stability. For example, when using C1=0.22uF (MLCC), R10 has to be at least 20kΩ. Less R10 results in a noise peaking at higher frequency until the circuit oscillates, but more R10 causes excessive broadband noise at the output, so you might have to trim it for your need. Also, if U3 is from onsemi when C1=3.8uF (MLCC), then R10 has to be at least 10kΩ to be stable. (but the noise rises to 400μVrms, so not a good deal) Again, these are only the results from the batch of parts I have, and your build might behave differently.

All caps used here are rated 600V or higher. They can be polarized ones but polarized capacitor tends to take a lot of place and the value can be too large for this application.

I wish this little application note might offer some help for those who want to build a power supply. Keep safe and good luck.

Hi, sometime ago I got a kit with upc1342v and NJW0218G/ NJW0302G transistors.
There was an instruction about how to set it (I guess the quiescient current), but I lost it.

Here is the schematic


I dont quite remember what to measure when setting the 5k trimmer (the current going through the power lines?).
How much the current should be for the given power transistors?
Also, if it is dangerous if I drop half the power supply when I am measuring (as it is dangerous with some chip amps).

Hi peeps,

I have a bit of a noob question to ask.

The value for this rezistor should be 1.4 kohm, right? Or am I missing something?

Thank you.

Hello Everyone,
I have read somewhere in the forum about tube rectification for PS of TDA 1543 ? Is that some joke since we are talking about max 8 vols at a very low current ? Is someone seeing some idea in that ?
Thanks

As I have two LL1667 5mA lying in my box, I thought of giving them a chance in the concertina, for a 15W 6B4G PPP for my 414-8A midbass 60-350Hz. With coils in opposite phase 15mA is max. Would be great if it worked as planned as there will be less problems with max swing compared with a conventinal inverted concertina with the available 270V B+. Will try to find a suitable low Cin MOSFET if the 2540 isn´t good enough. Driver before the concertina is a trioded 6E5P.

Could anyone please do a sanity check of the circuit. Sims good, but you can not see what will happen at higher frequencies. Tried to get capacitance and K figures from Lundahl, but they couldn´t help me.

Hi!

Has anybody got the PCB Gerber Files to make Giulianodes Relay–Based Interpretation of Bob Cordell's THD Analyzer Design please?

The Rotary Wafer Switch Assemblies and the wafers/screens, etc., etc., are getting very difficult to find and are a great deal more expensive than the total number of relays Member Giulianodes used!

There used to be a Dropbox link but this has been dead for years, and several other Members have said they have the files!

Chris Williams

Selling 1x ECDesigns U192ETL

USB to ElectroTOS/ Toslink converter, transport
all capacitors changed to Audio Note Kaisei BP
Including ElectroTOS cable

SOLD

Hi,

Do not ask me why, but after 10+ year an old obsession came back and I like to play with motors for turntables :- )
Maybe because I've recently acquired a Systemdek TT and want to improve.

Some 10+ years ago I wanted to play with 3 phase motors, I thought that should be the most smooth, silent but stable strong driving. Maybe THE ultimate driving. Since I had experience with DDS generators, to generate a precise, very close to sinewave (14bit, 400MSPS) what I can adjust each phase difference was not a problem.

Then I've started to search for motors. Had an expensive maxon and a lot of hard drive motors, some RC plane motors. None was good for being a TT motor, the reason was they liked to spin in high rpm, hated to spin in low rpm we need. Not only with my drive, I've acquired multiple divers too, result was the same.

A 2 phase driver derivated from that project, to drive the good old premotec/airpax/philips sycn motor - and that was great success. Especially with motors rewind to 24V. Sure it is overkill. Making 2 sinewave with 2 AD9954, than some signal conditioning and a power amp module (2x LM3886). I prefer it over the usual maxon 110191/110189 what I have to a friend.
I've used the DDSgen+LM3886 to 24V sync motor for a decade, I guess it will still win and will be my main driver, but I just can not stop playing with DC motors too, and now, I would ask YOU:

Do you have any tip, advice for a 3 phase motor suitable for TT, which may also accept (or even better is designed to) low rpm?

What is low rpm is relative I know. The sync motor spins 250 rpm, but with smaller pulley and driving on the outside of the platter we could go up somewhat (but for sure not to 3000+ RPM, where most motors started to shine what I've tested so far).

???

Thanks!
JG

Hi,
Trying to experiment for the first time. I've got some MAOP 10.2's well broken in, but currently homeless and I am considering grabbing some SB Audience 18SW450 18" subwoofers cause I've never really had "big displacement" drivers before.

Considering my first build with these to be an open baffle, cause I also haven't had an open baffle before, or even listened to one.
AND I'm also trying to design a speaker for the first time.

This is where I've gotten to currently.
Please note the shape of the baffle is a bit rough. Not deliberately wonky! Designed to be a winged OB.
1st order lowpass on SW at 100hz, 1st order highpasson MAOP at 600hz.



Without xovers:



I have a sneaking suspicion that the response on the MAOP is actually terrible. I don't believe BASTA models well above 1k though, so I'm not sure. Note the scale of the dB response.
I also don't like that the Full ranger is so far away from the SW driver (40cm).
I believe it should be within 1/4 wavelength of crossover to sum well? Which is actually kind of impossible with an 18" woofer anyway? With a non-symmetrical crossover, which should I be calculating for? The midpoint at 350hz? ~25cm

I don't actually really know what I'm looking at. I'm going through and trying to compare it all to the documentation that is online, and actually learn what I'm doing, but understanding what keywords I should be looking for in this instance, might accelerate the process significantly. I'd love anyone's tips or feedback here so I can move to my next phase of learning.

Is the peaking at the bottom end of the MAOP response "bad" or expected with OB?
What is a good goal response for the FR driver if this is actually as bad as I think?
How high in the bandwidth do I stop paying attention to BASTA's sim?
Does the SW actually look good like this with the lowpass in place?
Should I consider a H frame or U frame for the SW with a separate baffle on top for the MAOP?

Thank you for your time, I can't wait to hear your thoughts.

Dear diyAudio members and professionals!
I'm Robert, form Hungary.
I would like to join your community as an amateur electronics technician.

Hello, after looking around for options i would like to build my own volume control, relay based one seem to be one of the best and they allow me to play around with arduino again

some features im looking for

• atleast 1db steps
• 2x2 XLR Balanced Inputs
• 2x2 XLR Outputs

Microcontroller for:

• Display
• Rotary encoder
• Remote
• Mute Button
• Input Select Button
• Output Select Button
• Saving Volumes for each input

If Possible:
A "desktop unit" controlling the main unit (IR?)

imo the most flexible i stay with a relay board that basicly just contains the relays, i might do a seperate controller board (or wire it individually)

Questions i still have
1. i saw a design with 6 relais (-1db, -2db, -4db, -8db, -16db, -32db) but it seems this design has up to 6 resistors in series, isnt a shunt stepped attueuator "better" with only two resistors?
2. which type of relais/resistors? pref 0,1% precision
3. any recommendations or ideas are welcome 🙂 also when people are interested i buy a few boards more...

Hi,

I want to measure the noise the final tubes make in a PP stage. In other words, disconnected from the driver stage. With nothing connected to the finals G1 (except the negative voltage through a 100K resistor) I can hear some noise. With UL the noise is louder than in triode mode, but the nature / sound of the noise is similar.

I tried shorting both G1’s with a capacitor (0.15 uF) to ground. This resulted in quite loud pops (pop pop pop, every second) from the speaker. Then I tried both G1’s connected to each other with these capacitors, but this resulted in a high tone screaming from the speaker. There is no NFB in the amplifier, only UL mode when selected.

Do driving grids pick up noise when not shorted for AC?

I will hookup my spectrum analyzer tomorrow to get a beter view on what’s happening.

Regards, Gerrit

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Seems like there's some ideas that could be used for Audio DACs such as the divider driven LSB etc.

Hi. How can i sell my troubleshooting notes? I have been an audio Tech for over 40 years.​

Thank you

I have 4 new Talema 70065K transformers including the matching boards for sale, each for 20€ or all together for 70€.I have a few more of these 4 of these and can let a few more go as well. The Talema Transformers are very silent. The price does not include PayPal and shipping costs. PayPal is accepted, registered mail order buyer pays the additional 5% PayPal fees. With PayPal Freund the 5% does not apply and can be sent without tracking, the shipping costs within the EU are approx. 15€. Shipping within Germany €6. Outside the EU it may vary by country. Combined shipping possible. If you are interested send me a PM.

hello! i need help audison bit one processor is not turning on. Using remote turn on or audio signal turn on is not working. please give advice or somebody has a schematic at power supply side, i really appreciate.
thank you and keep safe

Hi there,
I am a guitarist and wish to take the smallest equipment to replicate my favourite guitar tone to various amateur live venues. My ideal equipment is a small ‘guitar headphone amp’. This unit plugs into my guitar and has a mini headphone jack output. Designed to practise at home. I assume I can send this into an ‘aux’ input in a venue’s mixing desk, but if they don’t have this option then how can I send it to one of the main line level inputs?

Pair of LL2785CAM 60ma amorphous single ended OPT for 300b or 2a3
Only a month old. Perfect condition.
Ideal upgrade for Elekit TU-8900E.
I can confirm that these sound spectacular!

These retail for USD482 each.

Asking USD700 or 550GBP pair
These are in the UK. I can ship worldwide at cost.
Payment by WISE or bank transfer only. No Paypal.

Hi all, I love diyAudio. Learn from everyone

Hi thanks for allowing me to join this group.
My system has been working flawlessly for years but today I noticed the main amp was still powering the main speakers with the blue off , power ring button released !
Still sounds great but would appear to be permanently active .

Thanks for accepting me, I've been involved with electronics since I was just a kid in the mid-1960s, In the 1970s I built my FM receivers which for some reason were scarce here in Australia when FM transmissions began, in the mid-1980 I designed and built my own solid state amplifiers, I also built my own transmission line laud speakers, from the late 1980's work pressures moved my HiFi on hold until I retired in 2021, since then I renewed my electronics to three-way active loudspeakers, last year I put together my first streamer, based on RP4 Allo digione streamer with ES9038 DAC, running on Volumio, which really impressed me, the noise floor has pushed some distance underground, Currently I'm trying to commission my new Protodac/RP4 streamer, trying to configure on MoOde, the available instructions are vague would be an understatement.

Hi to all.
Having purchased a TA-5650 with half working Vfets, I wanted to ask the experts what modifications is necessary to make it work with only one pair of Vfets per channel, as in the 4650. The voltages for the power transistors are almost identical and it is probably only necessary to modify the values of some resistances. Thanks for the help

This originally started in this thread which asks the question "why aren't we building a bookshelf synergy monitor" and answers it with "we are" or at least "let's try and see what we get."

I got inspired back in the Trynergy thread to build a semi bookshelf point source horn

The results with the SB Acoustics SB65WBAC25-4 were very encouraging that Bushmeister went and ordered the drivers and some off the shelf waveguides to start experimenting.

So here is sort of my vision of the end goal. It's all very fluid and we try to make things smaller where possible. The reality is it might be closer to a small stand mount. Decisions of which WG to bass the system on sets overall size.



Thanks to Bushmeister for the willing spirit to tackle this project. We are going to work together to come up with a new speaker with development and plans happening in real time ad hoc. It starts with Bushmeister picking the off the shelf 18 Sound waveguide.

Here is a summary of the completed speaker built by Bushmeister.

I guess we are calling the "XBush". Post 1248

Some highlights of the XBush:

Predicted sensitivity and response before EQ using a Harsch XO at 500Hz and SB23NRXS45-8 woofers:


The business side of the horn normally not visible when boxed up:


Mounted inside cabinet:


Finished speaker:


Acoustic XO slopes for Harsch:


Harmonic distortion at 100dB and 1m (nice!). Note that this is just a 2-wa speaker with two sealed 8in drivers - that manage to produce nice deep bass extension with low distortion:


Measured acoustic phase:


Measured Horizontal Polar Directivity:


Measured Vertical Polar Directivity:


Step Response:


Measured Group Delay:



######### XRK971's XBUSH ############

Not fully up to snuff yet when compared to Bushmeister's amazing effort, but here is Xrk971's attempt which uses a Faital Pro LTH142 waveguide, dual Dayton RS180P-8 woofers, and same SB65WBAC25-4 mid/tweeter:

Internals with all 3d printed driver to horn adapters (here shown with early version using DC200-8 wofoer):


Later version with RS180P-8 woofers:


Detail of SB65 throat adapter:


CAD drawing of adapter:


All 3D files (STL) for xrk971’s Xbush are here:
A Bookshelf Multi-Way Point-Source Horn

Fitting into box for first time:


Measured Polar directivity of SB65 in LTH142 waveguide:


3d printed woofer to waveguide adapter:


3d printed woofer chamber volume reducer plug:


Polar directivity with woofer holes:




Used in stereo with uTrynergy on left and Xrk's speaker on right:


Acoustic XO slopes of Xrk's speaker:


Phase of Xrk's speaker (still working on getting it flatter and proper 55deg phase bump for Harsch):


Harmonic Distortion of Xrk's speaker (not very good - many leagues below what Bushmeister is able to do):


I suspect the higher HD has to do with a number of things including: driver choice, cabinet volume and wall material, cabinet resonance damping methods, waveguide inertness via 4kg of epoxy Bondo, and larger holes (60mm vs equiv 29mm).
All pieces and adapters on Xrk's speaker were 3d printed PLA vs hand cut and epoxy for Bushmeister's excellent effort. Sometimes low tech gives better results.

So, my speaker is still a project waiting for more work to improve the phase, the step response, and improve the harmonic distortion.

Hi all,
with JLE TPA3255 amp in the table, i am trying to shunt the input stage, which is unuseful because drived with a high level differential DAC (SMSL SU-9).
The JLE amp is design with PFFB topology.
Tried yesterday shunting input stages not working. Amp goes to FAULT.
What i had done :

• Remove SE/BAL solder jumpers
• Remove opamps from sockets
• Connect J1-1 to socket A pin 1
• Connect J1-3 to socket A pin 7
• Connect J2-1 to socket B pin 1
• Connect J2-3 to socket B pin 7

Something strange is near 2.9V DC mesured at the outputs AC blocking caps.





Another try is removing 100k input resistors to ground (RA1, RA2, RB1, RB2). Same results.

If you like it, does it matter how it measures

Hey guys,

is there a possibility to switch between the EQ presets without connecting the DSP to a laptop?

Like switching from BT to Aux via short circuiting Ground and Stop.

Thank you!

I have a recently acquired Kenwood KD-770D with a speed problem. It appears that the PLL is not working because the table runs about 54 RPM at both 33 and 45 settings. PLL lock LED doesn't engage. I'd appreciate any suggestions on troubleshooting this table, thanks.

EDIT: I'm just looking for suggestions based on prior experience with this table (or similar, e.g. KD-990). Just trying to shortcut the solution with information from someone who's already been there. Cheers.

Hello,

I have for sale a few pcbs or finished modules for this amplifier.


More info about the Gaincore can be found here.
This amp is capable of giving 25wrms/8r with very low thd using a single 29.5vdc power supply.
It accepts sits and mosfets(to247 and sot227(pucks)).

The A2Cmx-V hosts an A2Cmx filter like this one and a negative rail converter this way you need a single rail power supply.

As a minimum requirement for the choke you will need 60-70mh and 2a.

2x Gaincore pcb + 2x A2Cmx-V pcb - 40€
2x Gaincore module(without Sit) - 140€
2x A2Cmx-V module - 120€

Hello. Working into a Williamson project, kind of. I can get 100 Vdc above onto the first plate supplying the first stage with the same 400Vdc as cathodyne did with 100k plate / 1k cathode resistors. I know the original scheme used 47k/ 470 ohm suplied at 250v above to get the same current. But the swing is minimal, I drived the amp with 200mVpk without nfb applied. Does it make a dramatic difference in respect with original circuit please ? Thanks.

This is my actual circuit.

Hello!
I just wanted to share something I found on eBay UK. Sold as base extenders, seems pretty useful to test tubes that are not pin-compatible with an existing amp or a tube tester.
Search for "McMurdo B9A Vintage Valve Base Extenders - Set of 6"

Hey guys,

my name is Chris and I'm from germany.

I have built two LF-Sat12 from a german developer (Jobst Audio) and a lonely.TH12 MKII (12 inch tapped horn) from a german developer (lonelybabe69).

Now I need some help with my DSP (NVArcher) and hopefully I'll get the needed information here.

Thank you!

Any audio enthusiast in West palm beach, fort lauderdale, miami area?

Martin

I just scored a Dynaco FM-3 for $60 to complete my Dynaco system. I’m going to clean and refurbish it. Are there any common things I should look for? I’m debating on changing out all the carbon comp resistors with new metal film ones. I’m going to replace the multi cap with individual caps under the deck. I’ll also do electrolytic to form on any signal path caps. What else should I look at?

I'm building an old school distributor machine for testing vintage motorcycle ignition systems. I want to flash LEDs to indicate when the ignition pulse is happening and would like to use 12V to trigger them to avoid needing the high voltage coil and spark plug. One hurdle I'm running into is the dwell time of the ignition pulse is far too long. The LEDs stay on too long to see any timing marks.

I've been searching for edge trigger circuit designs that will work for me but every one I've in come across the minimum on time is at least as long as the trigger pulse. I can make a microcontroller see a rising or falling edge and flash the LEDs for a few microseconds but it seems to go erratic at the upper end of the RPM range.

Does anyone know of an edge trigger circuit that can have an output that's shorter than the input pulse?

This: (one of the L15D boards in my 7-channel amplifier):



Not actually sure what caused it as all I did was change an opamp in the phase inverter buffer. But it was quite exciting, with flames, noise, and magic smoke everywhere! And it even blew the VCC leg off the opamp "Is something burning?" asked my wife, "Nothing to see here, move on", I replied sheepishly 😱. Lucky I have a spare board and inverting buffer.

But I have a question. Should I have fuses between the +/-55V 500W SMPS and the L15 boards, and if so, what value fuses should I use? And should I put one fuse in the +55V rail and another in the -55V rail?

TIA, Jon.

Hello all. I'm hoping someone more knowledgeable can help me out with the electronics on my filter. I'm using a piezo tweeter in a two-way with the following filter on the piezo: a capacitor in series and a parallel (shunt) resistor across the piezo element. I'd like to know how phase is affected (if at all) by this type of arrangement. As far as I know, piezo elements also behave like capacitors in circuit.

Thanks for any help. Let me know if I should post this in a different section.

Hey everyone! I’m new here! I’ve just gotten into designing turntables and audio equipment so I’m excited to learn more about how they function!

Hello DIY audio. Very excited to explore the world of audio electronics with you!