SemiSouth SJEP120R100 Single Ended Follower Amplifier, with Cascode and Choke Load

Always looking for a new diy project, I decided to do something with the two SJEP120R100 that I have. They started out in a diy stripboard version of a First Watt F2J. I really liked its sound, with its lower distortion, compared to the single ended SIT common source amps that I was listening to at the time. Now, I prefer the lower distortion level of common drain SIT amps, having built a few of them. So I decided to try a single ended SJEP120R100 follower amp.

The plan is to house it in a chassis that currently has two channels of a Sony 2SJ28 choke loaded follower. This chassis started out as a 2SJ28 choked loaded L'Amp (single ended choked loaded common source), and then FW F2J before its current iteration. The power supply is CLC, good for 23~24 VDC. The audio choke is Hammond 159ZC, 60mH, 0.7 Ohm DCR, and 2A DC current capacity.

So the plan is to make full use of the power supply voltage and choke current capacities. After some simulations, LTSpice showed that it may be possible for a choke loaded follower at 24V and 2A to output about 15W into 8 Ohm. However the dissipation may be pushing it a bit a around 45W, as the SJEP120R100 is a 114W device. To keep the same power output but with lower dissipation, I decided to add a cascode to the circuit.

The lower dissipation of the 2SJEP120R100 with the cascode in the circuit will also help in another way. When I had the F2J up and running, one of the 2SJEP120R100 had quite high gate leakage current. So running them with the higher dissipation would probably not work as the higher dissipation would increase the leakage current even more.

The schematic along with simulation results are shown below. The results are promising so the next step is to build the amplifier. Hopefully the amplifier will test as good as the simulated circuit.

24v AC or DC? Im thinking about using two of them in mono in an off grid situation running them on 24v Lithium batteries with solar charging. Yes/No?

I have started on the development of a variation of the well-liked (and well reviewed) LSA Signature 50 speaker. It will have an AMT tweeter and an all new crossover and will be called the Signature 60.

Preliminary results are very promising.

Predicted response (blue) vs measured (yellow) response for the crossover. The crossover is my own passive (inverted) quasi-transient perfect Harsch. The hand drawn thick blue line is the tilt of the Harman House Curve” to give a slight down tilt of the response to eliminate listening fatigue. Crossover frequency is near 5.5kHz. I am listening to it and still voicing it. Sound is wonderful. Superb drum kit realism. Vocals midrange are to die for:

Measured Step Response:

I designed the Signature 50 speaker for LSA quite a few months back but it’s finally starting to roll off the assembly line and will be shipping soon.

It’s a 6.5in 2-way bass reflex that uses a premium 28mm silk dome tweeter, and I gave details of some of the measurements earlier in the What’s on the Bench Tonight thread.



Predicted response of crossover:


Step response is quasi transient perfect (inverted due to mic response):



Custom crossover uses inverted passive Harsch topology of my design. All high quality parts like pure copper wire inductors, and custom made film caps and non inductive wire wound resistors:


Impedance as function of frequency shows a true 8ohm speaker with lowest dip at 6.5 ohms above 20Hz:


Here is the measured response (yellow) overlaid with the predicted response (blue) based on raw measurements from in-cabinet measurements of the drivers to account for driver offset and cabinet diffraction.



And here is the measured harmonic distortion as a function of frequency - measured at 2.0Vrms and 0.5m:


You can listen to the first sound test here:
Login to view embedded media
First review is now in from Tone Audio:
https://www.tonepublications.com/review/the-lsa-signature-50-speakers-2/

Here's a dumb question:

I've just built a passive sub with the Scanspeak 30W/4558T00. I'm using it with the TDAI 1120 from Lyngdorf and I'm using the onboard amplifier with a low pass filter of the Lyngdorf to drive the sub.

But how do I connect the speaker wire to the passive sub? Should I connect both left and right of both channels, or should I only connect one channel? I'm confused and I don't want to fry the driver...

Hope you guys can help🙂

Mads

Hi Everyone,
I am restoring a McCurdy tube based radio station phono preamplifier unit. It consists of a pair of AP 120 phono preamp modules, AM 410 mixer / monitor amp and a PS 850 power supply. It's light blue in colour. It is mounted in the console with the turntable on top.

Working on it is tedious, wiring and components are tight. Does anyone have any technical information on the circuits at all? There isn't anything out there except the AU 300 phono preamp. That gives some clues as to how they thought at least. These pictures may ring a bell with someone (I hope).

This gets restored keeping as much to original components to retain the sound character. The carbon composition (new) I'm getting are all out of tolerance, so I'm not happy about that one bit. Modern caps though. Sorry, it has to be reliable.

Thanks for any help at all.

-Chris

hi everyone
firstly i'm an electronics noob
i just purchased a box of fake fairchild bc337-25 from ebay(not for a project just to tinker with), and was wondering how i could test them, so as to compare to the specs of genuine 337's. the fairchild datasheet only gives characteristics information, and no suggested circuits to test.
so far i can continuously draw about 400mA through one of the fakes, but at about 500mA the smoke comes out.

so basically my question is what easy tests can i perform to best compare the fake against the real specs ?

warm regards
gaz

I have several Quad 405-2 amplifier which I’ve done the usual recap on. I always go with the usual TL071 OPAmp. I have always followed DaDa electronics way of fitting a 100uF polarized capacitor instead of bipolar on C2. They fit the positive leg of the capacitor to ground. I myself usually use low leakage Nichicon UKL capacitors for this position. I recently just thought about if it’s is a good idea to use a Polarized cap instead of the bipolar that was fitted there originally. So, this morning I measured a couple of my 405s and saw roughly 0.2mV on both the negative and positive leg to ground, which seems fine. But what does the collective knowledge here say, should I replace the polarized with bipolar caps instead? Pic borrowed from DaDas 405 revision manual.

HI
This is a question concerning the use and connexion a dac to a streamer and set up the hardware volume control.

My volumio is V3, My DAC SMSL M100 that is compliant with the hardware volume control.

When I connect the dac via the USB port I can set up in volumio the hardware volume control
When I connect the dac via Toslink, I cannot, only software volume control is proposed.

It that mean the hardware volume control only available if we connect the dac on usb ?
Did I miss something in the setting to allow the hardware volume control when connected via toslink ?

Help will be appreciated

Georges

Hey recently I've been wandering if I can save some cash on a crossover upgrade by using a mixture of Jantzen standard z , clarity cap CSA with a cdet 940c bypass cap to meld them together. I need to make up a value of 7.5uf so would use 3.6uf standard and a 3.9uf CSA with a 0.01uf cdet 940c. Has anyone on here tried these two caps together in the tweeter circuit. Thoughts would be appreciated. The other components I'm using are Jantzen superes on everything but the parallel woofer spot were Im using Jantzen mox. There also is a parallel cap in the woofer which is an electrolytic so I plan to use a cheaper jantzen cross cap. The 1uf cap will be a Jantzen standard.
Attached is a crossover schematic

So I'll try to keep this brief. I have been trying to fix this amp that doesn't want to power on.. Yes I have read all the posts and seen the most common problem with this series is the cap 196 that is part of the start circuit. this was a design flaw from factory and changing it usually takes care of all the problems. No luck. What is making things the most difficult is that all the circuit is very small surface mount. It seems from measurements that I'm not getting the Kickstart signal that should occur with the SMP power supply. I'll attach schematic. Looking at page 6, power supply. All my measurements are referenced to V_BULKRTN. At power on I get ~168vdc across the main caps after the bridge. At TP31(C8) I get 0vdc. At the top of the resister divider feeding V_KSTART I have 168vdc and at the midpoint of resisters 84vdc. So testing the Zeners, D28, D29 in circuit both the 16v diodes test good .7vdc forward and open on reverse. The D25 tests good also in circuit. I also notice that I never get 30v_CTRL and thus no 15v_CTRL. That goes to alot of stuff. So that is a good start. One question where does the 30v_CTRL originate?? Is it the power transformer circuit at B6?? But that is the primary so not sure?
I have many years of repairing equipment but almost no experience with SMPS supplies. Understand just a little from Youtube. Anyway this is a very common problem with this line of Crown amps. But not the capacitor it usually is.

Hello just brought Yamaha ns1000m from Japan ,one is working fine and other one is bass too low , after that remove from box and test without crossover bass driver is working fine . What will be problem network for driver is damage ?

Pls welcome key in

This pair mono mono power amp one channel suddenly humming loudly one day. Old amp so I try to repair by myself.
I unplug all tube and checked high voltage is AC 362V but DC is 445V, feel the voltage is too low (it must be 500V DC). So I think HV capacitor was broke down.
Original capacitor is Tesla 250uF 500V, its withstand voltage seems not enough, so I purchase KEMET ALC70 330uF 600V from Digikey and replaced it.
After running for a few days, the sound is getting better!
The following video is a record of my repair process：(Turn on English subtitles)
Klimo Kent tube power amplifier, repair by yourself - YouTube

Hi guy's ,

I am selling :

1 x QA401 audio analyser bought in October 2021 like new

1 x stereo 6 ohm 60 w load bench for amp testing , made with Caddock MP930

all cable and stuff needed

no parting please

500 euro


.

can somone send me a schematic diagram for the output module on a behringer NU4-6000 ... or send me the part number for Diode 44

Good Day All.

First post here, So, I took an existing toroid, It said 168va 30-0-30Vac I removed one of the windings completely and then rewound the other one, calculated I should be close to 12-0-12Vac, sure enough, I measured after the rewind and was sitting pretty at 12.2Vac per winding. This is where I am now left scratching my head.... If I take 12.2Vac x 1.41- 1.2V diode drop I get 16.02Vdc on the calculator, when I measure this with the meter at the caps I only get 15.48Vdc...... The rectifier is a repurposed RS1505m and I have 2 x 4700mfd @63V..... Does this sound right? I do not know so would rather ask.

Thanks in advance.
Regards
Charles

Hi all,

I'm planning on building the Fane 18XB standard 200l design, found in the link below.

https://www.fane-international.com/downloads/Cabinets18inch200Lres.pdf

It'll be my first build and I'd like to make some slight modifications to the cabinet so it'll fit a little nicer with some other cabinets that I plan on building. I was trying to model it in in WinISD to help me with this but a I came across some strange numbers when modelling the original.

The actual plans state 4 ports of 108mm to obtain the tuning frq of 35hz whilst WinISD suggested the ports should be 310mm, slightly confusing... I'd rather go with Fane's designs as I'm sure they're tested I think but can someone explain whether I've missed something here or if it's just a quirk of the software?

Also is there anything that I should bare in mind about making the box slightly larger? Is it enough just to make the ports slightly shorter to keep the tuning frq the same relative to the increased volume?

Any help would be much appreciated.

Thanks!

I’d like to use a force cancelling (magnet to magnet) bipole sub to go “under” some dipole speakers I’m planning. I anticipate a low pass for the sub at about 80hz.
In order for the force cancelling to work the rear facing woofer will obviously need to be electronically in phase with the forward firing woofer. This means the rear wave of the sub will be out of phase with the rear wave of the rest of the speaker. Am I designing in a problem or are the wavelengths so long that its just a chaotic system at those frequencies and so entirely unpredictable ?

O2 headphone amp output booster and upgrade PCB

EDITED and updated 1/21/2017. The latest V3.6 layout, schematic, BOM, part ID diagram and build instructions for this project are at a Google Drive link here:

https://drive.google.com/folderview?id=0B67cJELZW-i8Vmp5MDVLNzJxTGc&usp=sharing

Then the "V 3.6 1_28_2017" folder.

PC boards are available. To order a board see my vendor forum link: http://www.diyaudio.com/forums/vendors-bazaar/293309-agdr-audio-sales-thread.html

The final circuit uses the OPA140 or OPA827 (OPA827 is recommended) op-amps (FET input, DC precision, low THD+N) looped around an LME49600 audio current buffer on each channel to replace the O2 Headphone Amp's original NJM4556A output chips. The board produces a 93% reduction in the O2 amp's DC output offset voltage to around 20uV from the O2's standard 3.6mV, if using the recommended OPA827 chip. Output current capability is increased from 120mA per channel to 250mA for peaks - "music power" - playing music rather than sine wave testing. The O2's power supply has limitations that would prevent continuous current draw above 200mA per channel. The Booster Board adds: a headphone relay for zero turn-on or turn-off thumps; power rail reverse clamp diodes; and true zero ohm output impedance if the O2's 1R resistors are jumpered across.

PLEASE NOTE: I highly recommend using no higher than a 12Vac transformer with NwAvGuy's O2 headphone amplifier, givne the lack of heat sinks on the O2 voltage regulators. That goes for O2's with or without a Booster Board. You want at least a 12Vac 500mA transformer like a Jameco #101258. With the Booster Board the ideal transformer is the 12Vac 1amp (1000mA) Jameco #10081 for $1 more due. More than 1 amp wouldn't buy you anything additional.

There are several older versions of the board discussed in this thread, starting with the initial idea in the rest of this post below the asterisk line, leading up to the most recent V3.6. The project files for the older of these are under the "archived older versions" folder.

V3.5 changes

I corrected a bug in the older versions that caused the DC output offset to go up to O2 "regular" O2 headphone amp levels, around 3mV, when the volume pot was turned all the way down. The bug shouldn't have caused any audible problems for anyone since it only happened with the volume control rotated to the very extreme low position - no sound coming out. Now with V3.5 and above the DC output offset is the same ultra low 20uV even with the volume control down.

I moved the 1 meg ohm resistor that has previously been soldered in series with the sense wire that solders to the O2 board onto the Booster Board. The type of SMD diode for the relay was changed to 1A from the previous 3A, which was excessive. Placeholder pads (zero ohm resistors currently) have been added in series with the inputs to the LME49600, in case some other type of op-amps (other than the OPA827 or OPA140) require them. The RC power rail filters in series with the OPA827 power leads have their BOM values lowered from 100R to 1R. The previous value was set to coincide with the chip's datasheet PSRR drop. The new value sets the corner frequency at 72KHz, above the audio range.

The direction of the connection pins has been reversed from previous version in the build instructions, with the black plastic bar now up towards the Booster Board. The connection pins work fine either way, but one person using non-BOM IC sockets in their O2 had found that the pins fit best with the bar side up. I've also added wording in the build instructions to make sure the connection pins are centered top to bottom in the IC sockets if using the non-collet socket option in the O2 BOM, when soldering up the pins. The non-collet sockets have wide flat sockets for the IC pins which can allow 0.5mm or more of front to back placement. If the connection pins are not centered in the U3 and U4 sockets when soldering them they work perfectly fine, but one or both sets of will be at something like a slight 5 degree angle front-to-back.

The front panel green LEDs and their series resistors are now listed as "optional" in the BOM since most people have chosen not to install those. They have no circuit function other than just quick indicators to show the O2's power rails are OK (one LED on each power rail). They require two new small holes be drilled in the O2 front panel to see them, although the panel will clear just fine even without holes. Plus they cause a tiny amount of additional battery drain. There is a CAD file for a new O2 front panel with the LED holes at the Google Drive link above.

V3.5 was fabricated at a board house that allows the extra 2mm of board length needed to get all the connection pins onto the board, for the same price. Previous versions had the bottom two connection pins of U4 sticking out past the board (unused anyway) since the prior board house only allowed 50mm without a big price increase.

V3.6 changes

The left and right sides of the "tab" section are moved slightly, both 1mm to the left. This gives a little more room if a person has used non-BOM filter capacitors in their O2 which are slightly bigger diameter (one fellow ran into this with his Booster). Rectangular silk screen outlines have been added around the connection pin holes on the bottom of the board as a reminder to use the plastic-bar end of the pins up toward the Booster.

Placeholder pads added (currently un-populated) for bandwidth-adjust resistors for the LME49600 chips. The LME49600s are normally run in low-bandwidth mode (110MHz) since it is adequate for the OPA827 (or OPA140), pulls less idle current and produces less heat. But if someone has a situation where their specific headphones cause oscillation (very rare) the 100R bandwidth resistors can be added to bump the LME49600 up to high-bandwith 180MHz mode, for increased phase margin.

***************************************************************************


Sergey888 - I had an idea today for your OPA551 + linearization chip 2nd order circuit. 😀

Turns out there is a open strip of space in RocketScientist / NwAvGuy's standard O2 headphone amp above all the front components that is 28mm deep and the 80mm case width. A circuit board slid into the top slot there clears all the components and mounts perfectly between the battery connectors in the rear and the front panel. The is 5.5mm of free space from the top of the PCB surface, inserted into that top slot, and the top of the standard B2-080 case.

So here is your OPA551 circuit + linearization op amp layed out on a board that fits that space in the O2. I've left the area above the noisy AC input parts blank. The board connects to the O2 by using twisted pair wires going to DIP8 headers that plug into the IC sockets where the NJM4556A chips go. In other words, just pull out the two NJM4556A chips from the sockets, plug in the two headers like this one (Mouser #535-08-600-21)

08-600-21 Aries Electronics | Mouser

slip the board into the O2 B2-080 stop slot and away it goes! Well almost. One twisted pair of wires go to one NJM4556A socket header plug (input/output, signals in phase), 4 to the other (V+, V-, input/output signals in phase) but then one additional wire has to be soldered to a ground point such as the middle hole of the output jack connector. There is no ground present in the NJM4556A chip holes.

A few potential benefits of the OPA551 output chips vs. the NJM4556A chips:

* Potentially lower distortion given the loop with the LME49990 chip. I substituted the LME49990 for the LME49860 since no voltage higher than +/-15Vdc rails is needed anymore and the 49990 specs beat the LME49720/49860 slightly.
* One single OPA551 vs. the two paralleled sections of the NJM4556A on each channel. No paralleled outputs anymore. The 1R output resistors are no longer needed, no output resistors at all in fact, unless I run into reactive load oscillation issues during testing.
* Higher output voltage capability by 3Vdc peak! The 12Vdc voltage regulators in the O2 can be replaced with 15Vdc regulators (LM7815 / LM7915) and with a 16Vac or 18Vac input you now have +/-15Vdc rails. 😀 Looking through the voltage specs of RocketScientist's capacitors I think that I only saw one that has to be bumped up to a higher voltage. The LME49990 is not only specified at +/15Vdc, it is specified at 18Vdc. The OPA551 is good with either rail voltage too, of course. The existing +/-12Vdc regulators in the O2 can still be used too, of course. No requirement to go with a higher rail voltage.
* More power dissipation. I pitched RocketScientist once on bumping up the rail voltages to +/-15Vdc. He correctly noted that would push the NJM4556A's over their maximum power dissipation under some circumstances. No such problem with the DPAK OPA551's.
* It all fits, I think. The OPA551 is apparently 4.5mm thick and there is 5.5mm of free space above the board. We'll see what happens when it is soldered down with the solder film thickness. I've used 1206 surface mount for everything else.
* Short circuit protection form the TRS is maintained with the (short circuit protected) OPA551.
* Potentially higher current output. The OPA551's are good for 200mA each vs. about 120mA for the paralled NJM4556As, but I'll have to do some power dissipation calculations on the heatsink foil area and on the un-heatsinked regulators in the O2.
* Still battery power friendly for portable use! The quiescent current draw of the OPA551 at 8mA is about the same as the 9mA of the NJM4556A's they replace on each channel, a wash. So the added current draw from the batteries are just the LME49990's on each channel at 8mA each.
* Noise, or lack of it, may be about the same. 14nV/sqrt(Hz) for the OPA551 vs. the RMS sum of 10nV/sqrt(Hz) for the two parallel sections of the NJM4556A, which happens to also equal 14nV/Hz. The distribution over the higher frequencies is not the same though and the tiny 0.9nV/sqrt(Hz) of the LME49990 is added plus some additional resistor Johnson noise.

A lot more layout work to do, plus I need to add the bypassing. But it looks like it all may fit.

Hey Folks,
I would do this myself but I don't have access to a windows computer right now and I need to make a decision in the next day or so.
I'm looking at the RSS315HE-22 dayton subwoofer.
https://www.daytonaudio.com/images/resources/295-291--dayton-audio-rss315he-22-spec-sheet.pdf

I've tried having a play with hornresp (I actually managed to make it work on my mac), but have had no luck with WINISD.
It looks like a very small sealed box, ~25L gives a Q= .7, but it reaches max displacement really quickly.
My biggest issue is that I don't know how to model a bass boost for a sealed system in hornresp.
I've tried playing with a ported box, and ~80-90L gives a good response, but the port ends up being very very long to reduce port velocity below 17m/s.

Could someone have a quick bash at modelling this and seeing what an optimal design would look like?
I tried searching on the forums for previous modelling and didn't find much if any!
I'm looking for <100L Box with decent response down to 20hz.
I know I'll need a heap of wattage to make this happen. A 105dB Max output would be perfectly acceptable for me.
A small(ish) box is the main priority.
I will have DSP available.

Thanks for your time, even if it was just giving this a quick read.
Thanks!

hi there, first time posting.

i have a yamaha cr 2020 that was working fine, and just stopping clicking the relay and no sound.

its been recapped, and the service buillitens done. it has 2sd525 replacements.

on TR 714 i have 99 ohms and 0.068 in diode mode, reading between base and emitter. is this normal?

i was thinking this was my problem, but i dont know enough to be sure.

i have plus and -59 volts, but i dont know what else to look for voltage rail wise. any help would be much appriceated.

Hi all,

I am wondering if anyone approached such project and if anyone can point me to some good guides on how to do such a thing?

I have also heard about Solidworks, but not sure which one is better?

Thanks,
Pavlo

Friend of mine bought this house and this is the ONLY room available to set up as his listening room.

Not exactly a cube but room measures 17'4" x 18'3" with a 9' ceiling. Everyone knows a square room is terrible, but I've quickly learned that a square room where the ceiling height is a multiple is super extra terrible bad.

Initial setup was listening position 38% off back wall, JBL 4435's about 3' from each sidewall which put them almost right up against the main wall when doing an equal lateral triangle. There's no bass, tried multiple speakers with the exact same listening position, JBL L-300, Infinity Quantum 2's, Polk SDA 2.3 TL's, and many more, all speakers that should be able to knock a listener back in this room. Multiple amp's and preamps. The room has no bass, its like there's a crossover at 125hz or so, just nothing below that.

So my friend and I are on a wonderful journey together learning about room nodes! Yay!

My question to you all, if anyone here has any insight, can this be trapped/treated or DSPed out?

DSP would be an adventure, I'm going to try and teach him how to use a UMIK and REW soon, but I'm not great at it myself.

Another friend says lowering the ceiling by a foot and heavy corner and reflection point treatments are the only answer. The owner really doesn't want to have to lower the ceiling, and definitely isn't moving any walls.

Can it be fixed without changing the dimensions of the room?

FWIW, I've built a Neuorchrome Modulus 86 and a Parallel 86 about five years ago and think they both sound great. The sound far outpaced the cost.

Hello folks, working on this amplifier which blew one side of the P/S FETs (Q53,Q54,Q55). I replaced them along with burnt gate resistors. The replacements are getting hot very quickly so I suspect a bad PNP driver transistor. I’m having a problem locating that transistor and was hoping a schematic could help be locate it’s designation (Q01, Q02, Q21…).
I found some schematics online for other Focal amps, but none appear similar to this one.
Thanks in advance to anyone who can provide me with a scematic.

Hi all,

I would appreciate guidance for searching the world of Class D amplifiers, looking at a pair of amplifier modules / power supplies that can fulfil the following:

• 500-1000W @ 8R
• Subwoofer duty only
• Reliable
• Affordable

Can anyone recommend which of the 'Aliexpress' modules (or otherwise) can meet these? I have been burnt before by modules failing under load or just proving generally unreliable. I have been looking mainly at the IRS2092s and the UCD clones that seem to be all over there. I would ideally spring for something like two Hypex FA252 (it's for two active subwoofers), but they would blow the budget out of the water!

Many thanks in advance.

I'm interested in hearing how my speaker's sound changes when the room reflections are more controlled. I see lots of thin single material panels however I think I would prefer a wide band multilayer absorber to uniformly reduce reflections and not disturb the spectrum profile too much.

I found a some material tables Material Tables and a multilayer calculator Acoustic Modelling that both seem reasonable. I have (arbitrarily) limited the panel depth to 20cm. I'll post the design with measurements before/after.

If you've built one, I'd like to hear your experience / impression.

Panels Built and room measured:
1) Standing panel (H183 x W61 x D20 cm) - Standing Panel
2) Helmholtz panel (H183 x W61 x D20 cm) - Helmholtz Panel
3) Wall panel RockWool (H122 x W61 x D80 cm) - Wall Panel - RockWool
4) Wall panel foam pyramids ( 91H x W61 x D5 ) - Wall Panel - Foam Pyramids

I came across a topic yesterday that had me thinking about the slew rates present in audio and the max/min required for processing equipment - specifically, how to fill in the blanks in the following statement:

The highest slew rates are in the vicinity of <slew rate> and are frequently found in the waveforms generated by <instrument/voice/etc>.

My first guess (admittedly a WAG) would be the initial hard strike of a cymbal or something along those lines. Does anyone have any specific numbers and/or references on this topic?

Thanks,

Hal

Hello everyone,

I'm working on several of these Class D amplifiers for a friend and have a question.

These are very similar to the JBL EON 515 by the way; they look exactly the same.

Here is the question though. I've gathered all the necessary replacement parts from DigiKey & Mouser but there is one piece of the puzzle which is still a mystery to me.

What specific type of through-hole resistors are these?

From the color bands, one is 24KΩ and the other one is 75KΩ.

I ordered some metal oxide replacements from the stores mentioned above but my worry is that the replacements are much smaller in size and won't be able to handle the load. Someone mentioned these could be "flame proof" elsewhere but I cannot find exact matches anywhere.

If anyone has any input I'd highly appreciate the feedback.

So when crossing a "supertweeter" (or just a very high-extension tweeter, no matter the nomenclature) over with a full-range driver with a single low value cap to really flesh out the topmost octave, is phase aligning them important at those nearing 20kHz and above frequencies?
I mean, as critical as phase alignment can be with a range of frequencies.

If I use capacitors as 1st order for the full-range anyway, are the drivers now phase coherent in terms of at least the signal itself? Would they not be if the full-range was ran entirely crossover-free?
In relation to this, how important is physical time-alignment?

Good evening all,

This is my first post here and my first amplifier repair. If it weren't for the details I found here on DIY Audio I would have missed critical bad parts and probably found them the hardest way by damaging new parts.

I revived my old Peavey 1.3k that has been sitting in a failed state for nearly a decade. I found that it failed big time as they tend to do it seems. I found and replaced nearly 55 parts across the drive and output boards. I have a bit more work to do on it, I have a few more electrolytic caps that I am going to replace just due to age but I did a low power test and found that I have clean audio on both and channels.

As I found discussed here, I am going to install an accessory fuse block to add fuses between the rectifiers and the output board to ideally prevent so much damage should an output transistor fail again.

Thank you to the contributors in this thread:

https://www.diyaudio.com/community/threads/peavey-pv-1-3k-power-amp-repair-question.271480/​

I have spent the past few days searching this topic and I kinda hit a wall of contradictions.

For sure the JBL 2225h and 2235h have the exact same basket, and therefore a 2235h recone kit on a 2225h should make it a 2235h. Some will say the 2255h becomes a 100% exact 2235h. While others will say that the 4" motor is slightly different, and that therefore it will not become a perfect equivalent.

So... What's the last word on the subject? The topic is not about if a 2235h is or ain't a good sub. It's about the recone process.

Thanks in advance.

Hello,

I own an Audio Innovations Alto System, but without the remote control. Due to the design of this system, it cannot be controlled without the remote.

I am using a Logitech Harmony universal remote. Despite the system is in the database, there are important "missing buttons" and it's not possible to control the tuner functions. Only the "BAND" button is offered by Logitech.

Using an Arduino and a IR transmitter board, I have found some additional RC5 codes and now it's possible to control the tuner:

SCAN UP - RC5 code 0x45E
SCAN DOWN - RC5 code 0x45F

STORE radio presets - RC5 0x459

The Logitech Harmony can learn these codes and add them to the remote. Maybe this information can be useful for another Audio Innovations users without a remote or with a dead remote.

I have not found the PROG button code for the CD Player. I looks the remote uses also NEC codes for CD player functions. My Arduino reports the system code 0x21B2 and different codes for the PLAY, PAUSE, etc. keys

Best regards

Looking to buy a few VRDN boards if anyone has some spare ones they aren’t using or even some already stuffed and working.

Thanks.

Due to change of plans this chassis is up for sale:








All holes predrilled for DIY VFET builds.

Asking EUR 200 Plus shipping from the Netherlands

Hi, as the title suggests, I just want to point out this new interesting 18sound subwoofer:

https://www.eighteensound.it/en/products/lf-driver/18-0/4/18NLS4000

The parameters are interesting, in particular the xmax of 22mm and the xvar of 25. The peak-to-peak excursion is not indicated but seeing the thickness of the suspension I would say that it's very high. It's really atypical for a "pro" subwoofer, it seems more meant for home theater use. Another interesting thing is that, in relation to the size, it doesn't require huge cabinet (qts 0.35), less than 150 liters (B4 130L Fb @30Hz), not bad for 18" bass reflex but of course it can be profitably used in closed boxes with good equalization, the huge excursion makes it possible without issues

Hi guys, just a question for you experienced builders! What bulb wattage could I consider as correct in building and using a dim bulb tester? I should use it for amps startup together with a variac.

Thank you all,

Gaetano.

Hello.

Humble One is a small Class A amplifier.
Output is 11 Watt into 8 Ohm and 12 Watt into 4.
The amplifier uses only parts that are possible to find and buy.

Humble One is controlled by a quality opamp, OPA189, for low distortion.
https://www.ti.com/lit/ds/symlink/opa189.pdf

Output devices are MJE3055T and MJE2955T TO-220 transistors.
https://www.onsemi.com/pdf/datasheet/mje2955t-d.pdf

Bias in output is 1.25A Class A.
The power in each output device is 20 Watt and will produce heat.

Gain is set to x10.
The offset is very low thanks to the CMOS opamp.

Transformer should be 2x12VAC, preferably 100VA.

The circuit is simulated with very good results.

Hi there.
L
I'm struggling to find the replacement potentiometer for the volume and blutooth control. I need an 8 pin pot that is switched by click the shaft. The only on I've managed to find Is on off by twisting the pot

This is what the original one looks like

Any help would be much appreciated. Thanks

Paddee

Hi All, new here and looking to get some help troubleshooting a Tube CD player. I know it's not an amplifier, but I thought I would find more help here in tube amps than the digital cd realm. This is a BAT VK-D5SE tube CD player that uses 4 6H30 tubes for the output. One channel (2 tubes) works fine the other channel has a couple issues I think are related but maybe not. I do have the schematics, and before I go into gory detail and upload the schematics, I wanted to make sure I was in the right spot and could get some help?

Thanks a bunch
jim

I have two DIY SE tube amps I built. One with 6V6 tubes and the other EL84. Both are strapped as triodes. I prefer the triode sound to pentode wired and don't need the extra couple watts. I have tried to listen to them with no NFB but they sound a bit too harsh and aggressive through Klipsch Forte's without some global NFB using a 10K resistor. I read about similar amps with no NFB and how great they sound. So please fill me in on what could be going on.

Hi guys, 1 of my sonus amator electa amator tweeter and maybe crossover broke. Planning to replace them slowly. Just thinking

Anyone selling 1 SF electa amator speakers thats in good shape all original. Better than replace slowly my broken speaker

Music Lovers Today In This Article We Are Going To See The Stk4141 Ic Stereo And Mono Amplifier Board Review And Connection Details

[IMG alt="stk4141 ic
"]https://i0.wp.com/easyamplifier.com...e5-1-1024x512.jpg?resize=1024,512&ssl=1[/IMG]
This Stk4141 Ic Can Be Operated With a Dual Power Supply DC. This STK Series Ics Comes With Many Types For Example STK4141 Ic Can Give You 25 Watts Of Power Output Per Channel, Stk4191 IC Can Give You 50 Watts Of Power Output Per Channel, And Stk4231 Ic Can Give You 100 Watts Of Power Output Per Channel. These Types Of ICs Are Mostly And Easily Available In The Market.

We Also Wrote An Article About The Best Amplifier Board In The Market. You Can Read That Article To Select The Best Amplifier board according to your needs. These STK Series ICs Are Stopped Manufacturing From Long Ago. Now, These ICs Are Available In The Markets Are Duplicate ICs That Come From China And Korea. These ICs Also Give The Best Results Equal To Original ICs.


Nowadays, STK ICs Are Available In Two Variants: The ON Series And D Series.


This Is D Series IC. When It Comes To The STK Series Amplifier Board The IC And Driver Circuit Are Available Separately You Have To Solder By Yourself.


When Compared To D Series ICs ON Series ICs Are Given The Best Results Rather Than D Series IC.

This STK4141 ICs Power Supply Range Is As Per The Datasheet You Can Give A Maximum Of 40v DC. But You Can’t Run Continually With That Supply. Because These ICs Are Not Original If You Give That Much Power Supply It Will Damage Your IC Very Soon.


So In My Point, You Can Give A 24-0-24v Power Supply To This IC When You Are Using 4 Ohms Speakers. And You Can Get A Maximum Of 25 Watts Of Audio Power Output Per Channel. Whereas If You Are Using An 8 Ohms Speaker Then You Can Get A Maximum Of 25 Watts Of Power Output Per Channel With 27-0-27 DC Power Supply.

If You Assemble A Stereo Amplifier Then In My Recommendation Use A 20-0-20 Transformer With 3 Amps To 5 Amps And If You Assemble A 5.1 Amplifier With 3 IC Then Use A 24-0-24 Transformer With A 5 To 7 Amps Power Supply.

Now We Are Going To See This STK4141 Ic Stereo Amplifier Board Input And Output Connection Details​

This STK Series IC Comes In Many Varieties But Nowadays Only Three Types (STK4141, STK4191, STK4231) Or STK ICs Are Only Available In The Market Maximum.

STK 4141 Ic Connection Diagram


STK4141 IC Comes With 18 Pins, Pin No 11 To Give Positive Supply, Pin No 14 To Give Negative Supply Input, Pins No 3 And 16 To Give Ground Supply, Pin No 1 To Give Left Channel Audio Signal Input, Pin No 10 To Get Left Channel Speaker Output, Pin No 18 To Give Right Channel Signal Input And Pin No 13 To Get Right Channel Speaker Output. All The Connection Details Are Clearly Mentioned In The Driver Board PCB. If You Have Any Doubts About The Connection You Can Ask Me In The Comment Section

STK4141 IC Mono Board Connection Details​

If You Search In STK4141 Ic Datasheet You Couldn’t Find To Stereo To Mono Conversion Method. But Our Technicians Find La4440 Stereo To Mono Conversion Method Will Also Works On The STK Series IC. And Also Successfully Made It Too… Hays Off To The Technicians To Make That Happen.

Connection Details


All The Connections Are Clearly Mentioned In The PCB. And You Can Ask Me In The Comment Section To Know More About This Board.

And We Can Make This Board Stereo To Mono And Mono To Stereo If You Want To Know How Please Ask In The Comment Section So Will Write A Separate Article About That.

Determine the input voltage of the rcore transformer. Hello everyone, I have an Rcore transformer that I want to use for an audio preamplifier circuit. I have determined the secondary and primary wire groups by measuring the resistance of the wire groups. However, I cannot determine whether the transformer is a 220v or 100v input. We hope to help

Disclaimer: I do offer a competing product for sale: Neurochrome LM3886 Done Right, although, my kit is about 5x the cost of the eBay kit reviewed here, so I'm obviously not competing on price. Still, some may perceive this as a conflict of interest and I figured I should make it publicly known up front.

There are many LM3886 boards available in the market today and they all seem to implement various bits and pieces of the Typical Application schematic from the LM3886 data sheet. Some include the components necessary for good stability. Others don't. Most of the layouts are of dubious quality to say the least, but some are pretty decent. I decided to take a look at one of the circuits that looked pretty decent in the eBay pictures.

The XY LM3886 Kit is very popular here on DIY Audio and judging by the pictures of the circuit board, it looks like the layout should be decent. So I threw $11 at it (the kit was on sale) and had the kit within a week.

The kit came with the parts pictured and an instruction sheet in Chinese. No schematic or top level hook-up diagram was included. Basically, if you understand Chinese, you have enough information to put the components into the board but you're on your own from there. Thankfully, the silk screen on the board indicates the part values so I could assemble the kit. The kit included two shoulder washers, which aren't needed, and an M3 machine screw for securing the LM3886 to a heat sink. Excellent!
The passives look decent. You get a couple of noname 100 uF electrolytic caps for supply decoupling (National Semiconductor recommends minimum 470 uF) and the mute capacitor, along with another noname electrolytic for the feedback capacitor. The input cap appears to be a Wima polyester cap. Not the best choice of dielectric for low THD, but it could be worse. The resistors appear to be ±1 % metal film and measure within the ±1 % tolerance of the value marked on them. There is also a 0.15Ω, 5W power resistor that appears to be used to keep the amp stable with a capacitive load. Interesting choice. The three terminal blocks accept wires ranging from AWG 22 to AWG 14 and are of the leaf spring type rather than the better rising cage clamp type.
The LM3886 and the rest of the parts were in a regular plastic zip-lock bag inside of an ESD heat-sealed bag. From an ESD perspective, that's a no-no. The outer ESD bag is basically for show as the inner plastic bag will still be able to accumulate charge. Considering that XY has a machine to seal the ESD bags, I' surprised they didn't follow regular ESD practices and precautions and double-bagged the parts in ESD bags.

Now about the LM3886. I've always wondered how these Chinese eBay vendors can make money selling $11 kits that contain $20+ worth of parts. I think I've figured out how. The LM3886 that was included with the XY LM3886 Kit is pictured next to a brand new LM3886 from Mouser in the attached images. Note that the "LM3886" from XY is marked in ink whereas the LM3886 from National Semiconductor/Texas Instruments is marked with a laser. Note how the National logo on the XY "LM3886" isn't as crisp as the LM3886 from National? Note how the text on the "LM3886" appears to be right-adjusted whereas the text on the LM3886 follows western convention and is left-adjusted. The ink markings are a dead give-away. I worked for National Semiconductor from 2005 until we were acquired by Texas Instruments in 2012 and continued with TI until last year when I decided to pursue other opportunities. I have seen many, many National parts none of them were marked in ink. I did give XY the benefit of the doubt, though. It could be an old stock part... So I had a friend at TI look up the lot code "PM52AE". This lot code does not exist in the TI/National system. The "LM3886" that I received as part of the XY kit is fake. I am 99.999999 % certain of this and will send the IC to TI for analysis to find out for sure. Update: See the results of TI's analysis in Post #216.
Considering that Wima's capacitors are popular targets for copycats as well, one is left to wonder how many genuine parts are in this kit.

Those in need of more detail on the marking of National Semiconductor parts, please have a look at:
TI: Former National part marking Info
Chipdocs: National Semiconductor

OK, fine! You get what you pay for, right? I can't ship the kit across Canada, never mind to China, for the amount I spent on the kit. What's the big deal!? Hey, maybe it's a factory reject that failed on one parameter that I don't care about. Or maybe it's a completely different die in a package marked LM3886. Who knows? Needless to say, I was very careful when I powered up the kit.

The PCB layout is decent. There's a ground pour on one side of the board for the power ground and a pour or the top side of the board for the input and feedback ground. You really don't want the feedback and input ground together as the feedback current is pretty nasty and will create an error voltage across the input ground with high harmonic content. The two grounds should ideally also connect at the output ground rather than at the supply decoupling caps as done in the XY board. The saving grace is that the board is tiny, so the impedance of the pours are relatively low, thus, not much error voltage develops.
I do like that the supply routing comes in from the left (pin 1) side of the LM3886, though. This allows for the lowest possible supply impedance and keeps the traces close together to minimize rail-induced distortion. To me, this is the only supply routing for an LM3886 that makes sense. I'm actually a bit puzzled why so many have the VEE supply come in from the right. Anyway. Good for XY that they got the supply routing right. Aside from the ground pours (not planes!) and supply routing, the board is a basic "connect-the-dots" layout similar to what I'd expect for a beginner's first PCB layout. Pretty good, but there's room for improvement.

The kit came together very quickly. I think it took me 15-20 minutes to solder it up. For the test, I used a heat sink with a thermal resistance of 0.4 K/W to ensure that the IC would run cool. I used a pair of HP 6643A laboratory power supplies to power the board. I measured the THD, IMD, etc. with my Audio Precision APx525. The time-domain measurements were performed using an HP 3312A function generator and TEK 2465B 400 MHz oscilloscope (limited to 20 MHz bandwidth to provide the cleanest measurements). The frequency response measurements were performed using an HP 3563A Dynamic Signal Analyzer for the low end and HP 3577A Network Analyzer for the high end. Markers are placed at the -3 dB frequencies (3 dB down from the level at 1 kHz).

The supply voltage was ±30 V for all tests. A 10000 uF capacitor was placed on each supply rail to ensure a good and stable power supply.

Enjoy.

Tom

I made this chart of all the voltages you'd get using standard 1% resistor values for all the combinations of R1 and R2 where R1 is 120R through 1K and R2 is 120R through 10K. It makes it really easy to choose fixed resistors to get near the voltage you want without having to look up numerous standard values and do each calculation until you find something.

For example if you want to heat a 6.3V tube filament just find your voltage and R1 will be at the top and R2 at the left, in this case 6.25 volts is found at the intersection of 300R (R1) and 1.2K (R2) a nice voltage for the tube just under 6.3. If you wanted to hit it nearly spot on 6.28V is found at R1 = 820 R2 = 3300. Thought it might come in handy for others so contributing it here.

I absolutely love listening to music via DPLIIx and that is how I listen to all my music. This has become my preference and I'm wondering whether there are fellow members of the forum who prefer and enjoy the same. Having said that, I'm not happy about the fact that DPLII has now been eradicated from all the new processors and receivers. Got to hear music I know well via the new DSU codec but was not impressed, not sure if it has been improved to be as good as DPLIIx. I know DSU is designed to work with Atmos configurations but does it sound as good as DPLIIx is the question.

I suppose music that is mixed and mastered specifically for Atmos will definitely be more refined but 2 channel music content is still mainstream.

Greetings,
I'm getting ready for my first tube amp project ever, although it might be challenging I'm trying to build a guitar amp inspired from a Mesa Boogie (for personal use).

I bought a new transformer rated for the original amplifier, which supports 2x 6L6 + 2x EL34, with the following specs:

75W max. Raa ca. 3.6k
M6 Lamination: 3,75", Stacking: 1 9/16"
Mounting on 79mm x 54mm

Primary: Orig. colors in brackets
A1 6L6 Blue (Blue)
A1 EL34 Violet (Blue/White)
B+ Red (Red)
A2 EL34 Orange (Brown/White)
A2 6L6 Brown (Brown)

Secondary:
0 Ohm Black (Black)
4 Ohms Green (Green)
8 Ohms Yellow (Yellow)

As you can see the OT has two separate taps for 6L6 and EL34.

Since I don't want to destroy anything, I decided to do the math/simulation first and test the output transformer by connecting a variac on the primary and measuring the unloaded voltage on the secondary (8 ohm tap), until the secondary voltage reaches exactly 1V (as suggested by Uncle Doug on a YT video).

The values that I measured are:
For 6L6: Brown-Blue: 19.1V, Black-Yellow: 1.0V
For EL34: Violet-Orange: 15.27V, Black-Yellow: 1.0V

It gives an primary impedance of ~2918 ohm for the 6L6 tap and 1865 ohm for the EL34 tap, using the formula (8 ohm)*(Wratio^2)
Are these values compatible with a PP of the given tubes? I usually read much higher primary impedence values used for those tubes..

The specs say that it should have a Raa of about 3.6K, but my values are quite different. What am I overlooking? Perhaps should I have measured it using an 8ohm load?

Dear all,

happy to announce, that we are resuming demos of Siegfried Linkwitz´creation LX521.4 in


Corte Madera, CA (Nov.13th),

Healdsburg, CA (by appointment),

Houston, TX (by appointment) and

Stuttgart/Germany (by appointment).


Enjoy new cascaded, phase coherent analog crossover and low distortion 22cm Magnesium driver. These reports may be a teaser.


Feel free to book via email



Best
Frank

Audio-GD NOS 11 Discrete PCM1704UK DAC + Headphone amplifier / Preamplifier (with upgrades).

https://www.icloud.com/sharedalbum/#B0yG4VTwGGYt1IF

Asking Price: £1,100 (But sensible offers considered).

I bought this new (Feb-2017) from the wonderful people at Magna-HiFi in the Netherlands. Jos helped me immensely.

I had an upgrade (silver wires/connectors) installed by Jos before shipping to me in UK.

I then returned it and had Jos fit an upgraded Singxer F1 USB interface in Sept-2018

Works really very well.

Comes with: Original Aluminium remote; VDC mains cable with Wattgate 320evo Standard on one end

No original box (I never envisaged needing it as this was a keeper!)

I'm also including its companion M-Way – ACSS NTRL Ref Analogue balanced interlink (mini-xlr to 4-PIN XLR) for connecting this unit to an ACSS-capable power amp.

COLLECTION ONLY.

However, I'm happy to come to an arrangement to meet-half-way-so to peak and within reason.

I'm prepared to drive up to 30 miles from Malmesbury as part of the sale price.

I'm prepared to drive between 30 miles and up to 100 miles from Malmesbury @£0.40/mile (I'll charge for full round trip) to drop this off.

Please don't ask me to ship as I wont.

This is a great piece of kit. I'm selling as I have no where to put it and it's been under my bed for 2 years.

I'm happy to discuss more via messaging - just reach out.

UK ONLY - I WILL NOT SHIP THIS ITEM.

Thanks.

Please change my username from Pida to PKAudio.
Thank you

the idea is to put a couple of sensors in my system, excursion metering (and motor temperature metering). i want to know whats going on in my subwoofers. has anyone experience with this? links to diy metering projects much appreciated.

Hi everybody
Long time since I posted here in the forum but need some help/advice with this amplifier.
It is a Kelvin Labs Integrated (early series) that after a problem in my house wiring (damp in the walls) got hit by a surge after one of the many power cuts.
The problem is that now sounds like the is a car engine running in the background with or without signal in all inputs not changing with the volume settings.
I allready checked the power supply and changed all the caps (after 20+ years was in need) without change to the problem.
Traced the problem to the preamp, if I disconnect the preamp connection to the amp (at volume pot) the amp goes dead silent.
Here is my problem, on the preamp are no elcos just mylar and tantalum capacitors and don't know were to go from here.😕
Do I replace the tantalums with same type or can I use other type of caps ?
Any advice is welcome

Ric

PS; Don't know if this is the right forum but the amp is a Class A (?) one

try to repair the 6j1 preamp, the same scheme follows the original, only there is a modification in the psu, the plate voltage is 28 volt ct, the output of the regulator is lm317 and 337, the transformer is 3 ampere, the heater uses 1 ampere, the voltage using 9 volts is turned down using lm2596 to 6.3 volt dc... which makes I'm confused, originally I used 12vac 1 amper (it's safe) then multipliered it to 28 vdc. When using a model like this, it often makes noise, so I modified a separate PSU (the hum is gone, the noise is gone). The question is why the 3 ampere transformer heats up quickly even though the regulator IC is still there. It's just cool.....maybe someone can help

Taking of from here (post #485), I adopted this lovely gain stage as the part of a power amp - Cubie sounds great but Cubie2 manages to sound a bit better. 🙂

So Cubie2 is an extension of BAF 2013 preamp idea, with current mirror (Q3/Q5 and Q4/Q8) instead of resistor/CCS and introduction of negative feedback loop (R7/R16) which sets the gain at about 19dB. The LATFETs in the output stage (Q9/Q10) work in source-follower mode, without source resistors, providing some extended class A regime due to the square law transfer characteristic of MOSFETs.

The input JFET pair can be of any flavor (GR, BL or V), it's just important to dimension R11/R13 so to get about 10-12 mA flowing through the folded cascode branch (Q6/Q7/Rbias). Values on the sch. are based on JFETs' Id of about 6.5 mA. With such JFETs I got about 10mA through Rbias=330R which sets the LATFETs Vgs_Q10 + Vgs_Q9 = 3.3V and the output pair's Id at about 0.7A, but you can use the 1k pot instead of Rbias to set the output stage current to different value or to accommodate for LATFETs' differentiating Vgs/Id characteristic (my current batch of k1058s need 1.70-1.75V for Id of 0.7A and J162s need 1.55-1.60V for the same Id). P1 sets the 0V DC offset at the output, and it's very stable: +/-10mV from cold to hot and +/-2mV when hot. It's also very stable into reactive loads - testing it, I didn't succeed to make it misbehave.
R25 is there to load the folded cascode and determine the OLG (about 45dB) while the C3 shorts the gates of LATFETs for AC signal.
Full power before clipping is 34W_peak at 4R load with 1.3V_peak input signal and about 19W_peak at 8R load with 1.4V_peak at input.

The PCB dimensions are 70 x 25 mm, copper side view. The GND connection for decoupling caps (C5/C6) should be made with separate wires to main GND point, independent from signal GND on the PCB.

The PSU is same as here (post #62).

I tested the amp without the feedback loop (R7 and R25 go out, Rbias is split into 2 x 160R and from their middle point 1k connects to GND) and it sounds great too but with feedback loop it has a bit more definition and bass firmness. Those who enjoy "velvety" quality of BAF2013 preamp might like it more without the feedback loop.

I am looking for the Linear Audio Autoranger (or similar). Sadly, I didn't know I needed one, until they're out of production it seems.

https://www.linearaudio.net/la-autoranger

I've built a few voltage dividers and other reasonable solutions, but I'd like something more elegant / consistent / better.

If you have one you're willing to part with and/or could provide a link to alternatives, I'd be grateful.

Thank you in advance.

I have a good 2 months out of school and i decided to build a replication of the loudspeakers MBL 101 mkII. The monetary resources to build a clone at least parts of it are taken care of . The following are the complete information of construction regarding the MBL 101 mkII. This project is inspired by this thread My MBL 101E replicas

DELAYED
The Tweeter :
Number Of Petals - 24
Lamella Material - Uni-Directional Carbon Fiber
Lamella - 24mm x Unknown
Lamella Bending Radius - 25mm
Lamella Type - Non-Stitched Epoxy Bonded
Lamella Resin - MGS System 285 (H287S MGS HARDENER SLOW)
Lamella - Bake Temperature And Pressure Unknown
Lamella Prepeg ratio - 54% Carbon Fiber 46% Epoxy Resin
Lamella Glue - unknown
Dampening - Polyester Fiber (Twaron Angel hair)
Top Cap - W x 44.45mm
Top Cap Hole Diameter - Unknown
Mid Support Rod - W x L Unknown
Voice coil - Diameter 37mm ( 3.7cm )
Voice coil/Former - 4n Copper Wiring Used
Voice coil/Former - Aluminum Former Used
Voice coil/Former- Glue used is car break glue ''burned in at 500 Fahrenheit''
Voice coil/Former - Floats In Ferrofluid
Top Plate Diameter - 120.40mm
Bottom Plate Diameter - Unknown
Magnetic Material - Neodymium
Magnet size - 70mm ( 7cm )







IN-PROGRESS
The Mid-Range :
Number of petals - 12
Lamella material - Cross-Woven Carbon-Fiber
Lamella Tow - 1K
Lamella Type - Spread tow ( PrimeTex ZB )
Lamella cut - Bias
Lamella - 12.5mm x 1 sheet x 62mm
Lamella Bending Radius - 55mm
Lamella Resin - MGS System 285 (H287S MGS HARDENER SLOW)
Lamella - Bake Temperature 176F And Pressure 200psi
Lamella Prepeg Ratio - 54% Carbon Fiber 46% Epoxy Resin
Lamella Glue - Silicon Rubber Glue (Wacker)
Dampening - Polyester Fiber (Twaron Angel Hair)
Inner Ring- 40mm x 12.5mm
Inner-Ring Material - AL-MG ( Aluminum/Magnesium)
Inner-Ring Hole Diameter - 13mm
Outer-Ring - 90 x 12.5mm
Outer-Ring Material - AL-MG ( Aluminum/Magnesium)
Outer ring Hole diameter - 9.525mm ( 3/8" )
Inner-Hollow pass through -Rod - (OD)13mm x 5"
Inner-Hollow pass through -Rod (ID) 6.25mm
Inner-Hollow pass through -Rod Material - Graphite
Outer-Steel Support-Rod - 9.525mm ( 3/8" ) x 60mm ( 6cm )
Outer-Support-Rod Material - Super-Refined Steel
Voice coil Diameter - 5cm ( 50mm )
Voice coil/Former - 4n copper wiring used
Voice coil/Former - Kapton former used
Voice coil/Former- Glue used is car break glue ''burned in at 500 Fahrenheit''
Voice coil/Former - Floats In Ferro-Fluid
Top Plate Diameter - Unknown
Bottom Plate Diameter - Unknown
Magnet material - Neodymium
Magnet size - 12cm ( 120mm )

​

Delayed
The Melon :
Number of petals - 12
Lamella material - an alloy of Aluminum,magnesium,and silicon
Alloy ratio - Unknown
Lamella - Raw 50mm widest point x 20mm at end points x D x 360mm
Lamella - Assembled 10in x D x 16.5in with a lamella end of 4inch
Lamella Glue - Silicon Rubber
Lamella Bending Radius - Unknown
Dampening - Polyurethane Foam/Polyester Fiber
Copper Rods - L x W Unknown
Top Cap - W x D x L Unknown
Top Cap Hole Diameter -Unknown
Mid- Hollow -Rod - W x D x L Unknown
Voice coil Diameter - 100mm OD (10cm)
Voice coil/Former - 4n copper wiring used Likely
Voice coil/Former- Glue used is car break glue Likely
Voice coil/Former - Former Used Unknown
Voice coil/Former - floats in Ferrofluid likely
Magnetic Material - Ferrite
Magnet size - 200mm OD (20cm)
Spider ID-OD - 100mm (10cm)

The aluminum lamellas are a sandwich construction of two aluminum wedges held with epoxy resin Wrong. The petals are given 2 days to cool like airplane parts. layers of polyurethane foam are slapped on the back of each lamella to provide damping and additional mass. Each lamella is fitted with 2 thick reddish copper ''wires''. The wires are fitted into the vertical recesses of the petal. The wires add mass and an aesthetic beauty. The recesses of the driver are rolled and not stamped. The whole assembly rest on a cast aluminum plinth coated in automotive grade atracite metallic paint.

The sub woofer
[FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]The woofer is a 12" driver with a 4" voice coil. The voice coil is composed of black anodized aluminum that has a very low thermal resistance, approximately 1 K/W. This gives the system large power handling capability. The voice coil wire is also constructed of high temperature material able to withstand temperatures of up to 360¡C. The wire is glued with the same glue used in the fabrication of motorcycle brakes, and is able to withstand a temperature of 260¡C. As a result, it is almost impossible to destroy the speaker. The air gap is 10 mm high and the moving coil has a winding width of 24 mm. Thus, the speaker possesses an extremely high linear throw, with a maximum of 14-mm peak to peak. The maximum mechanical throw is two times greater -- 28 mm maximum peak to peak.[/SIZE][/FONT]


The cabinet :
Material - MDF
Material thickness - 30mm (1.25")
Port Holes - 2 inches in Diameter

Additional cabinet info
the cabinet has rectangular cross configuration to both stabilize the walls and hold the magnet with polyurethane supports.

specifications:
Crossover frequencies: 105Hz, 600Hz, 3.5kHz (Linkwitz-Riley, fourth-order). Acoustic center: 45" (1140mm) from floor. Frequency range: 24Hz–40kHz. Sensitivity: 81dB/2.83V/m. Nominal impedance: 4 ohms. Power handling: 320–500W continuous, 2.2kW peak.

Right now i am hopping to simply replicate the mid-range and used them as my stereo setup and as research and design along with resources progress the replication of the other 2 drivers will begin. I am learning to use Femm so that i can design and build the magnetic circuit for the mid range.The processes for building the mid range will hopefully be done in parts such as

Step 1 : Magnetic circuit fully designed and optimized in femm

Step 2 : ferrofluid properties such as viscosity,heat tolerance,and Gauss rating can then be calculated

Step 3 : Carbon fiber baking methods can be R&D

Please tell me your thoughts on such a project

For sale some parts from my 300b amp. All together 100 eu plus shipping inside EU.

Hi,

I've been recenlty doing all sorts of listening experiments, trying to get more familiar with my DIY speakers and speakers in general. Experiments from trying to find out how room affects perceived sound to how vibrations (knock) various parts of my speaker structure makes the freestanding waveguide resonate 🙂 Plan is to post about these for fun, even though they are not translatable through posts like this so you could have the same experience as I have had live doing these, hopefully my posts encourage everyone develop their listening skills and systems of course.

if you have some fun listening tests / experiments, please post them so me and others following can learn more 🙂

Here is fun set to start. Bought few compression drivers and was interested in how much their sound can differ in application, meaning that each was adjusted as part of complete system very close to same response would there still be meaningful difference? Well, didn't quite get there yet but had some time to make one round of measurements drivers playing alone, and thought to record small snippets out of that. There was 5uF capacitor in series with all, otherwise measured fullrange but then while exporting sound files I applied crude 4th order high pass at 1300Hz, about where it would be adjusted in application.

The test was not very scientific, although I tried to keep everything untouched, except change the driver. Waveguide is RCF H100 and drivers are hf10ak, cdx1-1747 and nd350.
HF10AK is measured three times actually, once with the same setup with cdx and nd350. Then twice with slightly different measurement setup with motivation to compare if there is difference between 5uf protection cap or series resistor with parallel inductor making high passinstead. I had to level match the inductor measurement as the resistor works as a pad.

Anyway, behind link thre is some wav files if you want to listen to. There is a snippet from a song and short white and pink noise files for each DUT. Also gated frequency response sweeps form on-axis. The files are level matched quite close, but frequency responses vary some. See text file inside to see which DUT-x- in file names is which driver 🙂

Well, haven't done much yet with the data. Plan is try to EQ match them with some tools and by ear and so on, just to manipulate them for a while to learn what the sound differences are. If you have a good methodology how to compare drivers in/for application, how to EQ match each for example, I'd be interested, thanks!🙂

https://www.dropbox.com/scl/fo/1kgiujc85ffjon3c9rppk/h?rlkey=ra4f89gldoabrjidc0swr1h1y&dl=0

For sale two of the most amazing car audio amps that I've ever owned. A legendary piece of equipment if I can say.
Pure class A quality sound. With tomahawk chips at perfect working condition.

Photos will be uploaded soon.


Price is 800 euros per amp plus shipping costs and PayPal fees if any. In case someone wants them both, the price is 1500 shipping included.

Thanks to Don Snyder & Chris.



Split off from this long post,

http://www.diyaudio.com/forums/showthread.php?postid=1819879#post1819879

- 2-sheets of 3/4" 15-ply ApplePly used.

- The blue CAT5 will be used to power some RGB LEDs to illuminate the 1/2" Green-Edge CNC Carving / access panel.

- Coil will be installed later

Here are my current build pictures:

Old Canon 10D, 28-135mm USM-IS, ISO100, F16, 1/80sec.






Some CNC V-Bit Carving Action:





Setup took about an hour

Does anyone know why Jean Paul left? and has his email?

Something like BAMA, but more consumer-oriented:
https://www.automatice.org/cgi-bin/index.cgi

Hello everyone!

Looking for input on the schematic I have came up! I'm new to audio diy so I'm not expecting that it is perfect.

Power input is +-35V

Thank you!

As fall and winter approach, time to start my yearly exercise in self indulgence. The introduction last year of the two dual 18 dipole subs to the studio has taught me not much can beat OB in this space so the focus on this project will follow suit. Hopefully these will fall into use as dynamic midfield mix/mastering monitors as we expand.

We added a 16 channel Trident console for a hybrid system this spring so the budget is blown for the year…..all spare change for this one resulted in driver element choices are all value driven. High efficiency means we won’t need a lot of power to drive these to crazy levels when needed…..a repurposed Parasound 5 channel home theater amp we picked up at an estate sale a few years back along with a miniDSP should take care of things.

I recently completed a pair of ACA’s from the store and the Redux version from Nelson Brock.

I like them both very much and they will be in regular rotation on my Forte IV’s. I think they just need a little push to live permanently in the living room.

I’m currently using a Schiit passive preamp with them and I’m satisfied. But I’m wondering if I build a ACP+ preamp, if I can expect to get anymore volume out of them? Connected through my BottleHead Moreplay I don’t notice much improvement, so not sure the ACP+ will give me anything.

Any insight on this would be helpful. Thank you.

Came across this and just wondering what people might think of a little more serious effort on this?
https://maker.pro/analog/projects/diy-simple-gu81-tube-hybrid-amplifier-130-watts-rms-in-a-class

I learned about the FP230 series of transformers from Triad. These are flat pack, 2 primaries and 2 secondaries wound on a 4 chamber bobbin, so with guaranteed insulation between the windings. The 230 refers to the secondaries: 2x 115V. I used these as filter chokes in two Futterman OTL amps, where they perform very well.
https://www.mouser.ch/c/power/transformers/power-transformers/?q=fp230

Another application is as a center tapped PP choke. Due to higher RDC at secondaries, I connected the transformer as shown. The resistors and pots are to increase the voltage drop, which is used for biasing the output tubes. The amp uses an input transformer, I choose the cheap TY-250P, also from Triad. The cathode resistor is 154R. I choose it over LEDs or CCS as it helps in keeping the current through the output tubes stable with varying mains AC (tested with a Variac). The actual B- is rather - -190V DC. For the output stage, the 4P1Ls were wired as triode, and fed from a VCCS.

The power supply uses a PT from a defect SS amplifier, which puts out about 88VAC. This goes in the doubler, and with a level shifting cap, to form the negative supply, with some additional filtering.

As directly heated, the 4P1L starts drawing current way before the ECC81s are hot and conducting, so I combined the capacitance multiplier with a crude current limiter, based on the 2x 6.2V zeners (had these hand, 12V Zener also ok) and the 2x 10R resistors. When too much current is drawn, the zeners start conducting and the gate of the Fet is pulled down. This works indeed. As a DC coupled amp, it is indeed nice to have a current limiter if something fails during operation.

As output transformers, I used Talema 7VA toroidal power transformers (230V to 7V). Unloaded, they measure about 8V at the secondary, so they present a 6k6 primary at 8R secondary.

The amp works, currently biased at circa 35mA per output tube. 1W at 0.35% THD, about 2.5W max. The frequency response is circa -2dB at 20kHz, and this is solely due to the used OPT. At the plate of the ECC81 the frequency response is flat until at least 30kHz. Amplification is 60x and very low distortion, so the PP chokes are doing their job.

I tested current disbalance in the FP230-25, and it can take some mA without getting much worse (I will get the exact numbers). The toroidal OPT were tested with a 5mA disbalance (so one side pulling 5mA more than the other). The THD doubled (to 0,6% THD at 1W) and the bass response suffered a bit. I will be using these as mid/high amps with a 12dB HP at 600Hz, so I do not care much about the bass performance.

There are no caps in the audio signal (not that I think that they hurt, but wanted to try it like this). There is still caps in the PS, so I am considering to feed the OPT through a choke, to isolate the amp from the PS and force class A operation (learned that from Lynn Olson’s website).

What I do specially like is that one can have quite a good performance as PP choke from a 10 USD part. Also, the 6 USD TY-250P surprised me.

Now I still have to listen to it!

This is one of those days. Many of us have experienced similar days, I’m sure.

I started my day off with some good coffee. Kettle on. Fresh ground beans of my favorite variety that is easily bought locally. Slow pour into my hodgepodge design of cotton fabric filter plus tea infuser. Then I performed the ritual powering-on of my audio systems. There are of course multiple ridiculous steps, just like the coffee. Preamp (two switches), power amp, speaker selector… No magic smoke. Preamp and power amp in the secondary system. Then fire up the music server. I have to restart squeezelite on two of my four synchronized piCorePlayers after multiple hours of inactivity for whatever reason, so I tapped multiple things with my phone browser to do that. Finally, ready to select some music. What do I feel like today? Kid in a candy store! Random mix of locally saved music felt right for today.

Time to sort out breakfast for my kids. After that’s done, time to casually read diyAudio threads.

After mulling over the myriad unfinished never-ending audio projects I have catalogued in my brain, I decided to do some DSP PEQ tweaking of my speakers. Many “WOOOOoooooiiiiiii” iterations later, I thought I had reached a significant improvement in the low end. That was the goal for this tinkering exercise, so I felt rather accomplished. It sounded pretty good.

Time to futz around in the back yard a bit before the rain comes. The weather has been deliciously autumnal in the mid-Atlantic the last few days. I harvested the waning tomatoes from my container garden and dead-headed some flowers for seed collecting.

With the success of PEQ fiddling, why not see how it sounds in the vinly rig? Sure. Sit back and rela— But what? The right channel is very weak. Oh no. Did my beloved vintage RIAA stage finally go belly-up? After testing all the physical connections and not getting any benefit, I decided to bring the whole vinyl rig out for troubleshooting. It is not a trivial task to disconnect equipment from the main system. Carefully threading cables in a tight corner. I brought it all to the dining room table to see where the problem was. Thankfully I have any number of unused power amps not in rotation to contribute to the effort. Commandeering the entire table with the turntable, multiple preamps, buffer with gain, an ADC, a power amp, and test speakers… It was an operation. should have grabbed a picture of it, but I was trying to be efficient.

To my surprise, everything worked fine. No recurrence of the weak right channel. All components working perfectly. Relief, but perplexing. I switched things around enough to make sure all was well, then hauled it all back to the main system. More futzing with cables and tight spaces.

Finally, all things checked out. Time to sit back and enjoy an album.

Insight, execution, joy, shock, fear, perseverance, vindication, wonder, all in the day of diyAudio.

Enjoy the journey!

Hi,

I have the above amp that was stuck in protection mode (red flashing LED). I removed the covers and saw the main reservoir caps on the PSU were swollen, so I replaced those and all the other electrolytics on the power board and for a few days, it seemed to work ok. This morning, it's dropped back into protection mode without anything connected to it.

Does anyone have any ideas where I should look to try and get to the bottom of this? I've measured all output devices and they seem to be fine (speakers are also ok).

Also, does anyone have the full service manual for this model?

Thanks

I have a two 3" granite surface plates that I use for a turntable stand. I recently found a new bearing that is taller than the stock one and would like to bore a 2 inch diameter hole in the lower plate. The original cut-outs were done by a water-jet machine but transporting the plate is difficult and I'm not sure if they can do it without a CAD drawing anyway. Any opinions as to the feasibility of a DIY solution? The hole doesn't have to be perfect. It is just for clearance. The hole would go in the second picture basically in the center there the heaters meet.

Hey all, does anyone have a schematic they could post for an original AudioControl 2XS crossover? Or in a pinch 2nd generation unit?

Thanks
/Rob

Hi i do have one very old Rodec Mixmaster II in sad shape that i would like to restore.
Cant find information at all about it. Its the Canadian version (made in canada).

schematics would be nice.

already contacted Rodec.be

thanks.

Hey guys! Just recovering from a late summer c0uld and inflamed middle ear/s (there's 2 of them, right? Not actually a 3rd whole ear as such?). My hearing has been mostly down a few dB, but strangely UP in the bass. Particularly at about 77 Hz, and something has been making a rather steady tone at that frequency 24/7 and it has been driving me up the wall.

OK, I'm no professional like Clouseau, but I've been motivated to do some serious sleuthing. This is what I've got so far:

SPL: extremely low. Maybe 5 or 10dB above absolute zero. It easily fades and disappears momentarily with the onset of louder sounds, and if there's too much other noise I just won't hear it at all. It seems loudest at about 4 or 5am. Right in the middle of my beauty sleep!

Initially, I had to rule out mains electricity, so I switched off the breakers late at night. No fridge, no pumps or anything. I put the clock in a cupboard. No change.

Maybe it was tinnitus? Nope. From experience, that was usually some transient ringing that would shortly fade, and only on one side at a time. Or maybe a high frequency cicada like noise, but not constant bass in both ears.

I'd heard it before, but initially wrote it off as probably a water pump, so I put it out of my mind. But then we moved house, and then it dawned on me that the new place was producing the exact same sound from a year ago. As if the walls themselves were throbbing, and the tone seemed a bit louder if I was close to a wall or in a corner.

I haven't tried recording it yet. With my current non-setup it will likely be all noise and no signal, but it's coming.

I tried to pin-point the frequency by humming it and finding it on my keyboard, and eventually got a D# almost 2 octaves below middle C.

Then I found that if I played a D (natural) really softly with a mellow Rhodes-like sound and waited for the levels to balance out, I could get the two tones to interfere! Gotcha!!! The bastard!

Maybe it was underground mining or a factory or something nearby? The two houses are only a few km apart, so it still could have been a local source. But then I visited family over 40km away, and it was the same.

~~~
At this point, the only thing that seems to vaguely make sense is that it's a Schumann resonance of the earth (one of the harmonics anyway). But those are meant to be radio waves. Bizarre!

SOLD

Modushop steel 4U Deluxe chassis, black, new in box. 300mm deep, 10mm faceplate.

$250 incls shipping within Continental US. Payment via Paypal.

Vifa silk dome tweeter? Came out of an old m&k bookshelf. Is it worth keeping or just another silk dome? Looks like another Polk audio silk done without the trilaminate coating I highly doubt it can handle the volume that a poke silk dumb can handle but I might be surprised. Denmark sounds impressive

I'm a gigging guitarist, and until recently I was using a 30w Mooer Baby Bomb as a power amp to drive an 8 ohm load for performances. However, the Baby Bomb developed a harsh ground loop noise reminiscent of chirping crickets- I'm not sure if it's the power supply or not, as a new one has not arrived yet, but I decided to try building a DIY power amp of my own, as it sounded like a fun project.

I stumbled upon this diagram of a stereo amp using two TPA3118 chips. I only needed it in mono, so I essentially cut the diagram in half. I also ended up going with a TDA8932 chip and a TDA7492 so I could try multiple options- the TDA8932 is listed as 35w at 8 ohms, and the TDA7492 is listed as being 2x50w at 8 ohms, which I bridged- if my understanding of impedance and power is correct, it's still 50w at 8 ohms (going down from 100w at 4 ohms), but it should be putting less strain on the amplifier.

I wired everything up according to the diagram above, using the specified capacitors and potentiometer for volume. I let the solder cool and plugged everything in to test, and while I was able to get sound, they're both pretty quiet. At half volume, the Baby Bomb would be peeling the paint off the walls (and would distort past there), but at full volume with a 24v power supply, both of these weren't even loud enough to keep up with a drummer. By absolutely cranking the output of my preamp, I was able to get the TDA8932 nearly there, but at that point some kind of overload protection seemed to kick on and the chip started to cut out.

What might be affecting the volume level of these chips? Everyone else I've seen online seems to get plenty of volume out of these, but I'm not sure what I'm doing wrong. Should I be using a different chip?

I encountered a significant setback while studying the process of measuring the Equivalent Input Noise (EIN) of a microphone preamp. There are several tutorials on EIN measurement available online, but I have many areas of confusion, which has resulted in me spending over a week without fully understanding how to calculate it.




The simplest method I found is to obtain a known gain and then insert a 150-ohm plug to measure the noise. In my case, the RMS meter in Reaper shows -80.8dB, with a gain of 57.7dB. This results in an absurd value of -138.5dB, whereas the EIN (Equivalent Input Noise) should typically be around -130.X. Clearly, there seems to be some issue.

Login to view embedded media The second method I tried was from YouTube. The challenging part of this method is that my sound card has analog knobs, so I cannot precisely control the dB gain. I used the same -50dBV generator as the person in the video and tried adjusting the dBFS portion in REW to exactly increase it by 50dB. However, using their calculation method, I only obtained an EIN of around -126dB, which is a completely different value from the previous method.



The third method, I'm not entirely sure about. I used a known voltage, such as a 1mV input, to calibrate in the RTA interface within REW. Then, I disconnected the sine wave input and plugged in a 150-ohm load, switching directly to the dBu interface to view the values. This value seems to be very close to the "normal EIN value" of around -130dB, but I highly suspect it might be a coincidence because I haven't come across anyone using this method, at least not in tutorials available on the internet.

https://benchmarkmedia.com/blogs/app...c-preamp-noise
and this one completely different… I can't understand it at all.

I am soooo confused，and need some help.

I made some weird planars with a 180 degree arc. and here are 2 tunes. where i show the dispersion, but besides that... its weird how it interacts with the room, when gated i get a flat response (relative) but then in real live its waay to mid/high heavy.
So i might need to tone that dispersion down so it does not interact so much with the room ? since it only adds up from 500hz to 10 khz or something.... (see measurements)
well who knows.. here it is

Login to view embedded media here are 2 measurements in the midle of the room one gated... and one not gated. and you can see there is quite some excesive mid/top added when not gated 5-9dB, while the top top end above 11khz does not add. witch makes the perception of me listening in the room pretty mid forward.... at least thats what i think. its sounds incorrect, while i love the stereo image.
i know there shoudl be a difference between the 2 but it looks excesive compared to flat panels. (i guess way more reflections because of the dispersion?)

Sales site Huobix question​

---

Never mind. Got it figured out. Thanks for looking.


https://www.huobix.website


Thanks in advance.
Norm