My faithful hakko 929 finally bit the big one, went in to solder, pressed and the iron hand piece part broke in half.

Playing with new FX-951. Seems to be the perfect replacement! Need to get a few additional tips. Perfect timing. Iron pre kit, XA 252 is at post office for pickup Monday, just in time.

Russellc

SOLD

Before I try and figure out Shipping these monsters, I thought I would throw them up for local pickup. (Mobile, AL)

I am currently cleaning out my closet prior to yet another move/downsize prior to retirement. Keeping my commercial equipment, shedding the DIY. Starting with the heavier stuff.

Amps - $500 with pickup

• Monoblock pair DIYAudioStore Deluxe 4U cases (custom front panels) M2x - MJ on/off circuit - Toroidy sealed transformers - SLB power board. M2x boards with upscale components, and Harris MOSFets.
• Daughter cards - Norwood, Cedarburg, Tuscon, MountainView, Austin, IPS#6, IPS#7, and some assorted DIP Op Amps, Hakuin cards in the boxes now

Speakers $1000 with pickup (I will get the shipping boxes out of storage as well)

• Zu Audio Druid V in gloss black
• Zu Audio Undertone Subwoofer in gloss black

Hi,

While swapping big output caps on my Scott 388B I incidentally broke a diode leg in the amplifier output section. The diode is marked SR1-5 and described in the service manual as "silicon rectifier". I attached diagram of my Scotts' output section with these diodes marked.
I know very little about diode types and I could use some forum help to choose the right type for replacement - specific to the power output section of the amp. I only know that the diode should be rated for 70V as this is what comes out from the connected transistor.

My questions:

• what type of diode is good for amp output section(normal rectifier or maybe Schottky)?
• does material (silicon in this case) matter?
• amperage rating? (my guess 3A might be good enough but I don't really know deciding factor here).

Thank you,
-Peter

Im going to build a MC pre https://diyaudioprojects.com/Solid/JFET-MC-Pre-Preamp-Kit/
but what are the substitute for 2sk170 BL?
What jfet can I use?
I can even use smd.
suggestions

I need to lengthen the ground wire from the transformer. What’s the best way to add a few inches? Twist together and solder, crimp connector, jam strands together so they’re intertwined and solder…?

Bought a pair of floor-standing speakers from a DIY guy. I have positioned it in a relatively small room(12x11ft)! This sounds okay but I think the highs are not sharp enough and the soundstage feels below. If I bring my ears down (sitting on the floor) at the tweeter level, it sounds right.
Is this speaker design flawed? Should I use stands for this to compensate? Or any other recommendations?

Spec-
Woofer: HiVi D6.4 MKII
Tweeter: HiVi K1
Crossover Point: 2700hz (12DB/Octave)
Impedance: 5 Ohms
Sensitivity: 92DB
Power: 100-200(W)
Dimension: 35x10x12 (in)

This group helped me with some early questions on my brother's TT set up. I am grateful. That thing is still going strong.

I am hoping for some additional information for another situation...

I know enough to be dangerous, and I am familiar with the basic TT terms. I can find my way around basic test gear (DMM and scope) along with REW etc. as needed.

I could read more, and learn more, but I'm in a time crunch, and ... truthfully, I won't likely ever own another TT for myself. This is also a unique situation (for me).

Here's where I find myself.

A good friend has inherited a very costly (by my definition) TT rig. Without getting into debates re: its merit. It holds incredible sentimental value, and it will not be replaced / sold for something better, but cheaper / DIY etc. We both assume, but we're not sure, that everything was transported safely and that all the parts and pieces are there.

I feel confident (for now) with a bit of coaching from this incredible community that if it has been transported well, that I can get it running for him ... and perhaps get it running well. From what I've seen so far... everything looks in order, but I have not seen it in person.

Relevant stuff -

TT - Basis B Signature 2500. It does not have the super-fancy external motor control / PSU.
Phono Stage - Asthetix Rhea
Arm / Cartridge / Stylus - Unsure at this point. I haven't seen it in person, and current photos are not usable.
No vacuum gizmo.

What I am hoping for...

Some basics of what to check other than does it turn and make music.

The Rhea is a tube stage. So, is there anything a novice DIYer with ambition could be pointed toward to make sure that it's working 'properly' other than turning it on and making sure it plays music? I'll assume that no one has twiddled any knobs and that his father had it set up for the cartridge... but is there an easy way to check that? I have no idea when it was last powered up. I'd prefer to not even open the lid, but if I should, I can. I'm familiar with safety practices when working with tube gear. Are there any 'simple' measurements someone should do, or is it best that if it makes music to just leave well enough alone? When I buy a used amp, I run it through some basic distortion tests. Is there something similar for a phono stage?

I am familiar with TT basics like azimuth and tracking force, but do these things typically go 'out of adjustment'? What about the TT could or should be checked to ensure that no harm comes to it when we first give it some juice and put a record on? I can grab some proper tools as needed, but I don't know if I need one of those protractors or ... anything.

The motor / belt and table are currently separated. Any guidance on belt tension and how to set that? Manuals for this thing rare as hens' teeth.

Lastly... I'm assuming, but I'm not certain that the speed adjustment / control is... well... contained within the motor assembly and is simply automatic. There are no adjustments that I'm aware of at the moment. Guidance is appreciated. It looks like you just plug it into the wall, and it's supposed to turn at the right speed regardless of mains fluctuations (even w/o the super fancy optional PSU). Change between 33 and 45 by moving the belt on the pulley. It'll only be used for 33. How can I check the proper speed? With all the extra things that were used by the previous owner like a super-fancy record cleaner etc. I'd assume there's a strobe (do people still use those?) or something to check RPM, but if not I can find one.

Any guidance is greatly, greatly appreciated in helping to get what hopefully will be an incredible TT rig playing beautiful music in its new home. I know I can't wait to hear it... and I'm not even a 'vinyl guy'.

With thanks in advance,

Patrick

Going back to school for a degree in Electrical Engineering is the obvious path I see. But perhaps there are others that I'm not seeing? Are there trade schools that would be helpful in this regard? Other possibilities?

Assume for the sake of this post that I'm specifically interested in formal approaches, and set aside the wealth of information available on the internet.

Open primary . help welcome for a replacement or repair .

Here's a no feedback solid state tube amplifier😉 for that rich warm sound, let comments flow

Last month had a bad fight with this amplifier. Has been in service, not repaired.After figuring out that without schematic will be shooting in the dark... also because of curiosity for their "no global feedback" design, decided to draw it off from the PCB. And there was no surprise - it have global feedback. Also distorting capacitors, wired like 69 on the input... they are there for nothing different than distortion.

Bad construction, difficult for repair - should remove front panel, knobs, input selector, power LED... after that the PCB can be slightly turned aside.

First problem - caused by previous service - was broken the power input screw terminals - the wires from transformers are single core (directly from the transformer winding) and are not flexible. It's very easy to break the terminals with them.

Second - 0,7V offset in the output. Was suspected transistor or diode... all measured good on the PCB. Started off-PCB check - gain, leakage... all OK. Moved to the other channel and others channel transistors on this - the problem remains. Checked all resistors... still not working. At that moment started to draw the schematic 😀 After all... few hours later, found that C6* is shorted and can measure 100 ohms on it


As we can see, there IS global feedback 🙂 T8-T9 what are doing there? Soft clipping, current limit, active biasing?

I would like to buy 2 pieces of cd player IC ym7121c
EU source if possible. Thx.

I wonder if there is any ready made boards for a pre-amp with both balanced and unbalanced inputs/outputs.

I know there is many other aspects to think about, for example passive/active but just want something good and not noisy 🙂

I'm not so good in electronics (maybe I can improve?) but can solder somewhat OK.

Understand that this is a vauge question, but I appreciate any directions.

Thanks!

Hello my dear audio DIY fellows,

I bet many of you in here already tried out field coil driver for open baffle design ? What is your recommendation for a good field coil driver for OB design that do NOT break the bank? I'm looking for good/ hifi quality sound here.
So far I have tried out so many FR conventional magnet drivers (Ferrite, Alnico, Neodymium) from 6.5 in to 15 in FR with very good result for OB.

Lately, i came across some readings about file coil driver that peaked my interest. Before jumping into the deep, I want to seek your advices for some good FC driver brand, should I go vintage or a good/new brand? What are they ? Some of the Do's and Don'ts that I should watch out for with the Field Coil driver ? One thing I know is you need a really high voltage supply for FC driver, should I go SS or Tube PS for them ? with a high voltage supply, does it affect my preamp/amp output in anyway ?

Any inputs are welcome and thank you in advance!
Warmest regards,
Tom

Hi everyone .
Do you think it is possible to turn any ground referenced stereo power amplifier into a bridge amplifier using
the following totally differential OPAMP ? . for example I have a my-ref .
Thank you
https://www.ti.com/lit/ds/symlink/opa1632.pdf?ts=1687362270520

Which manufacturer? Good for audio?

Hi guys.

My old generator developed a fault over night.
The frequency cannot be adjusted with the big dial anymore. It appears to be stuck at the low end of the dial. It can still be changed with the 3 range selection switches, but still stuck in the low end of the respective range.

When the unit is switched On, the frequency starts high and the drops over the first 1-2 seconds. The drop looks very "controlled" and well behaved. - I'm suspecting the the error is around the sweep function, but none of the other controls vary the frequency.

The output signal looks perfect and amplitude can be adjusted.

I know that a few components look very hot, but I think they are located in the amplifier section and I'm pretty sure that they looked burnt the past few years ( should replace them, yes..).

Any ideas?

I have the service manual, but I cannot figure out where to start looking. I would really like to restore this beauty. Look at the internal build quality.

Kind regards TroelsM

Either I haven’t had my coffee and these lines are misleading, or I’m a bit behind about subwoofer development. Is this just a 4th order bandpass sub (albeit mounted at angle ?why)

I've noticed you can buy good and old studio-monitors for cheap, for example, the PMC TB2 cost 350$: The drivers cost around 180$, and I'd gladly add 170$ to avoid the carpentry and deal with the electronic wires.

Although I'm looking for more offers like that, with better-more expansive drivers.

My budget is around 1,200$.

P.S. I got a powerful amp.

Im going through the gain stages of my amp, just to get a grip of each amplification stage. Trying to understand how the coupling caps effect the phase going into the last stage of preamplification...
Strange as I see it, the last coupling cap would have 2 signals 90 degree's out of phase... I must be missing something?

Really started because I couldn't find any information about the tube config (long tail, cascode etc..) that fit the last stage in this 12AU7 config..
Do tubes (grid to plate vs grid to cathode) change the phase that Im not accounting for ?

I'm trying to help a buddy out. He has this autoformer that he's looking to sell. It was part of a pallet of Amazon returns that he bought. I think it was returned because the transformer mounting bolt was slightly loose so the transformer wiggled a bit. I opened it up and there's no damage inside. I tightened the bolt and tested the transformer. It works as far as I can test it.

This autoformer takes 110/120 or 230/240 V AC and turns it into 120 and 240 V AC. It's supposedly rated for 5 kVA. The power rating is probably inflated a bit, especially given that you can't actually pull 5 kW from a regular wall outlet, but judging by the size of the toroidal power transformer in it, I'd say it's probably around 2 kVA. It would be useful if you have a European appliance that you want to use in North America. Do note that this is not an isolation transformer. There is no galvanic isolation between input and output.

Anyway. These run about $200 on Amazon. Any reasonable offer will be accepted. The transformer is located just south of Calgary, Canada. It comes in its original box so it can be shipped, but it's pretty heavy so shipping will probably be a bit costly.

Tom

Hey folks

Apologies, I'm still in the asking question phase of life!

I've built a reactive load box, here is the circuit, with a tap off to go to an audio pcb board (between the 47k and the 1k resistors)



In LT spice it gives me the impedance response I want and a flat frequency response. However, when I test it with ARTA and white noise I get this:



Really (obviously) noticeable when I plug in the guitar amp and listen to the output (I have a speaker emulator on the headphone output)

I can't work it out. Is it layout? here is the prototype:



????? Maybe lead dress

I decided to ask since i really like what im hearing and would like to understand what makes this type of sound and build something like this in future:

--(images added)--


-Storytime: While ago i was listening for different kind of standmount speakers on different dealers.
I did ask to hear between two harbeth speakers they had in store, monitor 30.2 and c7es-3.

This store had system with rotel amplifier that had both speakers connected at the same time and, you could switch between two of them with A/B switch on remote.
I switched between them and they were ok for my taste, but after a while i suddenly heard a weird thing when i switched.
Volume was too high suddenly, so i turned it back down but behold:

This really perplexed me, suddenly sound was really so much better.
Instruments size and vocal were so much bigger, they were closer to me and sound had weight, body & more relaxed and presence. Everything was easier to hear, more clear, soundstage was bigger but also more diffused, not so easily localised. If single speaker was like 6-7 in scale to 10, suddenly sound was solid 9.

What had happened was that this amplifier could play both A and B at same time, and suddenly both speaker were playing same time.

------------------------------------------------------------------------------------------------------------------------------------------------

-My question is, what do you think made this difference?
Was it bigger area cm² of midwoofer & bass?
Was it placement, two midwoofers playing side by side? (wide baffle & "virtual" large midrange?)

-Can it be replicated with big single midrange driver?
(no comb filtering)

I am having too much fun in a simulator and discovered that by measuring collector currents for transistors in the output stage can show if it distorts the signal by deviating from the perfect sine wave. Also, spikes of current apparently indicate of quasi saturation operation.

Throwing together 3EF with two output pairs I have measured currents on all three transistors: pre-drivers, drivers, and outputs.

What I observed was that out of the three - driver transistor was working the hardest with current spikes up to 80mA while driving 4 ohm load with 20khz sine wave signal at full power.

I therefore was wondering how to fix it and got an idea - what if I add another driver transistor in parallel?

I measured currents from pre-driver and driver collectors and attached are screenshots to compare both.
Visually comparing between both it can be seen that spikes were reduced to under 36mA for driver transistors.

Just a though for discussion.

I have my neighbors Pioneer GM-D9605, out of his truck, Local shops could not find why the truck battery going dead. He replaced this amp, problem solved. Now we wish to repair this old amp, any one have thoughts on what to look for. i have service manual, good documentation, been few years but i used to work all kinds audio equipment. I am one of them old fart techs dumb enough to take on any job. First look at the amp i see no problems, all components look good, no obvious defects. As i read the service manual this amp should draw almost zero current when idle. Any suggestions much appreciated.

Hi Folks,

When I tap the up or down volume button on my remote control the amp volume jumps up or down too much for low volume listening. One workaround has been to lower the input volume, unfortunately that is not an option when listening to vinyl.

I have solved this issue by adding a resistor to the volume motor circuit. Less power to the motor yields a slower motor rotation speed. My concern is does adding a resistor cause issues with the IC (L293DNE) that drives the volume motor. I've thought of changing the input resistance to the IC but don't have SMD or resistors in that Ohm range. At least for now I can enjoy late night listening at low volumes. Any guidance and/or feedback is appreciated.

Motor coil resistance ~ 22 Ohms
Voltage at coil when pushing volume control button +/- 4.4 Volts DC
Added resistor ~ 47 Ohms (0.4 mW)

Schematic attached - Volume motor circuit circled in red.

I've been working on and off on this M-500T that I just can't seem to fix, primarily because I just don't understand the circuit. Hoping someone can help.

Initially the unit was not coming out of protection. I was able to resolve that by fixing cold solder joints. Ended up re-flowing the entire mainboard and power supply. All output transistors check out, out of circuit on my Peak meter. Once I got relay click, I installed new caps on the mainboard and the smaller caps on the power supply. All voltages from the supply are there at the initial measurement points, but then it starts to change halfway through the schematic, which I also don't really trust because it already has some mismarkings at the power supply, but anyway...

I don't understand the switching power supply and how it works. And i don't know if it's relevant to the issue I'm having, but basically I'm supposed to be seeing a + and - 14v at IC101 at pins 4 and 8, and I'm not. i'm getting around .6v +/- which goes up to maybe .7v if I connect an input signal. I've pulled both zener diodes and checked them and they read fine. I'm presuming that if both voltage rails are missing at that chip, then it's something that would be tied to both and not channel specific. That's what I'm having trouble finding. I'm seeing 74v and 43v +/- at points on transistors where I should be only seeing less than 2v.

This is my last ditch effort to try figuring this thing out. I'm attaching a pic of the area of the schematic where I'm supposed to see the voltages, for what it's worth.

Hello!
If you want clean analytic sound, this is not for you.
But if you want sweet JFET sound you should build this amplifier.

The JFET adds distortion. The level of distortion is set to THD 0.050%.
Mainly 2nd and 3rd harmonics.
This is fed into one high quality opamp that can drive headphones well.
The opamp can deliver like 100mA.

This schematic shows an amp for 32 Ohm headphones.
For other impedances I have designed additional schematics which will give the same sound quality.
I may post such schematics upon requests.

Hello.

I have the following situation.
I'm building a power supply for an IV converter for a DAC, which should deliver +/- 32V (NTD1, designed by OPC) using TPS7A4701 for the positiv Voltage and TPS7A3301 for the negative Voltage. The current consumption of the IV converter is 180mA for the negative and the positive voltage.
I had toroidal transformers made with an output voltage of 24.5 VAC and 50VA power. I am using active rectifiers based on the LT 4320 (designed by Prasi). The no-load voltage of the transformers is approx. 27.3 VAC. The no-load voltage after rectification including filtering (before the TPS7A4701/3301) is 37.50 VDC and exceeds the maximum input voltage of the TPS7A4701/3301 by 1.5 VDC.
I don't know at the moment how far the voltage including consumers will drop.
Now to my questions.
1. Would I damage the TPS7A4701/3301 if I connect the unregulated 37.5 VDC - and then see how far the voltage including loads drops?
2. Can someone name a simple but good solution, how I can lower the voltage in front of the TPS7A4701/3301 by about 1.5 - 2V. Preferably without major effort such as pre-control. Just put 2 diodes in series between them? Simply looping in a resistor (CRC style) in front of the regulator only brings a voltage drop when current flows (?) and I don't know whether there will be an overvoltage including damage to the TPS7A4701/3301 in the meantime.
I would be very happy about your recommendations!

Cheers, Niels

https://darko.audio/2023/08/fomo-fi-thorens-limited-edition-td-124-dd-looks-sumptuous/

dave

For sale a pair of Satori MW16P-8 like new.
Slightly used for testing.
Tags not soldered.
Retail price is 165€ each. I’m asking 165€ for both. Pp fees and shipping to be added.

So, i have a little issues that might need extra hands to get it right, last night I did power up my 300 VA toroidal and it is making a quiet buzz.
On smaller toroidals this usually means there is a short somewhere right, but in my case the buzz persists continuously with the transformer bolted down, or with bolt removed, at a different location, and with bridge+filters connected or not.

Does anyone know what might be causing this ?

Hi everyone ! I have a problem with a JBL PRX 515 speaker amplifier! after having replaced the damaged mosfets in the woofer section, as soon as I turn on the amplifier, it doesn't start! looking at the diagram I found on the internet I noticed that on pin 11 of U2-B I should have 4MHz and instead I have nothing! I tried to replace U1A but nothing changed ! Has anyone had the opportunity to repair these modules? do you have any advice? I am attaching the schematic of the entire amplifier

I'm a super novice. Just inherited my grandparents audiolab setup with a 8000p and 8000c, audiolab Cd player, and rega planar 3 TT. Now I'm enough of a music fan that I currently own a Pro-ject carbon TT and I recently refurbished my dad's 1976 marantz 2235b (35w I think?) which is pushing a couple old Boston Acoustic bookshelf speakers for my 800+ LPs (the BAs are not tiny but they aren't gonna shake the house either). I feel with this inheritance I'm at an order of magnitude up from my current rig. I'm looking to understand how to configure the 8000c and 8000p together with the rega, what speakers should I get for the mains (probably going to turn the BAs into satellites), should I get a sub, and Anything else I should know. Any help would be so appreciated!

Trying to do a DIY turntable on the cheap and wanting to calculate pulley size. Trying to use a Pioneer PXM-032 motor from a PL-115D. If I can arrive at the motor speed my friend will help me turn the drive pulley from delrin. Thanks.

Evening all, I mentioned in another thread I loaned a friend a Behringer amp and have now found quite cheaply the 4 channel amp epq304 for him so that I can reclaim my amp for subwoofer duty.

The fans are quite noisy and research on the web has come up with someone completely disconnecting them, someone adding resistors to slow them down and some one replacing with quieter fans.

I have attached a photo from the web but checked that my friends is identical layout.

Why am I posting in the power supply section you ask?

Well I want to fiddle with this amp because I may have other uses for it but don’t want to get killed in the process.

In general domestic use with fans it runs stone cold. Without the top lid it runs stone cold and oddly is not as noisy. I have touched the heat sink on the amp section and survived so it is not live but am far more wary of the power supply.

My primitive way of experimenting in this instance would be to run the amp reasonably hard and touch the heat sinks to check temperature. Obviously safer would be to first unplug the power cord but for this type of power supply would, in general of course, the heat sinks be live and even if the power cord is removed would there be enough energy stored to shock?

I could measure with a multimeter but are these ac or dc and is the reference chassis ground or does the power supply float.

Any comments appreciated and please understand that I am at least smart enough not to kill myself.

Thanks, sp

Hi All, I'm completely confused with the whole idea and would really appreciate some advice.

I have installed an Audison F8.9 DSP/AMP and 3-way active front stage in my car using Audison VOCE tweets, mids, and midbass.

Also an Audison Prima APBX 10 AS2 Active Sub

I also have the Audison BCON wireless streamer and have connected that to the DSP to stream music from my phone (Samsung S23 Ultra) into the BCON and straight to the DSP via Optical Toslink.

The BCON is certified HIRES and I've been feeding it LDAC.

I'm really happy with the sound quality as it is (I've finally After many months managed to tune the sysyem using REW) and it sounds great, but as with anything you always wonder if there is more you can squeeze out?

My question is will I hear any benefit from replacing my phone with a DAP or using my phone with a USB Dongle?

I was just about to purchase an A&K S35 but then realised it doesn't have optical output on its 3.5mm jack!

Do any of you have any recommendations on the best route to go down to upgrade the source? As I understand from reviews of the Samsung S23 Ultra that the audio ability of the DAC isn't very good......

I see there DAP, DAC, USB dongles, and then there is the Fiio Q11 which appears to have optical output? But it also is a DAC/AMP will the AMP part of it blow my DSP if plugged into optical toslink?

And I also don't quite understand if I even need to get a new source or if I just need a USB C to Toslink connector and then feed that from my phone directly to the Audison F8.9 DSP as that 'may' already have a DAC built in and may be better to use that? I've done some reading and can't see if it has a built in DAC?

Link to my DSP is here
https://www.fourcaraudio.co.uk/brands/audison/audison-prima/audison-prima-ap-f89-bit

I'm looking to get more into diy dac & headphone amp projects, especially interested in trying out some of the classic or lower cost designs to get some variety & cheap fun into my second system.

This amp came back with 1/2 the PS fets blown. I replace the bad bank of FETs, the driver MPSA06/56, and 10ohm gate resistors. Pull down resistors are good measuring 820ohms. Drive signal to the PS FETs looks OK, but the fets run hot at greater than 13vDC at B+.

I replaced the 1n4742 diodes, checked the 10ohm resistors to PNP collectors.

The amp appears to be able to pass audio under mild bench load just fine.

As soon as more than 13vDC enters the amp, the FETs heat.

Removing the rects and the PD Fets never heat (Though fets gets driven to 100%)


If I mount the amp to a sync, it'll hold for a bit; but I'm afraid it'll come back (again) once strained.

There doesn't seem to be much consensus on this topic. Some say that you should only pair high sensitivity compression drivers with similarly sensitive drivers. Others say that a good lpad makes compression drivers just as suitable a match as any other tweeter, even to lower sensitivity woofers. What do you think, and why? Or, what have your experiences been?

This one came in with half the PS blown, and half of each channel BJTs. I'm troubleshooting the power supply with rectifiers removed, and I cant get the original blown fets now replaced with IRF3205 to not over heat. I also replaced the other side's PS fets which were not blown so all matching IRF3205 now. I found a 12v ZD near the corner of the board just near the inside speaker terminal had also blown short. The PS fets which get hot are the ones also near the speaker terminal. Drive signal to the gates without fets looks strong, but when installed the drive signal gets a bit wavy even when fully driven. I also replaced all MPSA06/56 drivers in the PS. Clean square wave is coming off the TL494. When I apply 14.4v, the amp powers with rects removed and only draws about 0.3A. When I drop input voltage to about 10vDC that side of the PS FETs will overheat and draw excessively. Its defiantly a weird one IMO. With rects installed that same side of the PS overheats easily at any voltage. I've serviced a bunch of these 225HCCA amps but this one is getting me.

The drive signal looks OK, maybe a bit poor on both sides of the PS for my liking but both sides are matching and the other side stays absolutely stone cold.

I think the muting circuit may operate on the faulty side of this amp.

This amp was severely over-loaded, and possibly over-volt. I found both rail caps partially detached and replaced both and the main PS filter caps.

Why does this amp draw excessively when input voltage is dropped?

Looking at restoring a Luxman L58a and when looking at the schematic I've found an adjustment pot in the psu that isn't mentioned in the adjustment procedure, anyone known what its doing? Please see attached pic

Hello diyaudio people !
Nice to meet you all !

Hi! Looking on schematics of the Vox pathfinder 10 which I found on this forum. There is U1B op-amp which is configured as inverting band-pass, but after that I can't see nothing that will invert this signal back. So are this guitar amp supplies inverted singal directly to speaker? Or my understanding is somewhere wrong?

Hi. I have this amp on the bench, it was just very dirty, not used for a long time, dirty pots, in short, things like that. Adjusting the idle current as specified in the manual, 15 minutes of warm-up, between 7 and 15mV, so far, all good. The problem is that if I leave it operating with load and sine wave with the heat sink hot, the quiescent current drops to zero and as it cools down it returns to the preset value. Is that okay? It has happened to me with other amplifiers, but it never drops to zero.

I built a linear supply for a Pass ACA amp. I don't understand the rectified voltage. It is much lower than I expected.

I attached the schematic.

My question is why is the voltage after the bridge rectifier 26.5v instead of 31v? My experience is that voltage would be [(22.2VAC x 1.4) - 0.6v].

BTW, the filtering seems to work pretty good.

Thanks,
Dan

Can I feed the + and - signal directly to Q1 and Q2? And double up R1 and R2?

Preferably a Mk2.
I am in the UK.

For sale: Digilent Analog Discovery Portable Analog Circuit Design Kit with a BNC PCB

price: 170euro/$170

shipping costs: shipping from the Netherlands, should be about $7-10 within EU and $20 to the US, in any case ask and I will tell you for sure.

Barely used, only for measuring THD and as a spectrum analyser during one project, but then was replaced by a Handyscope, works great!

Works with Digilent's software as well as nice external package for working with audio amplifiers:
Login to view embedded media

Features:

The Analog Discovery’s analog and digital inputs and outputs connect to a circuit using simple wire probes. Inputs and outputs are controlled using the free PC-based Waveforms software that can configure the Discovery to work as any one of several traditional instruments. Instruments include:

• Two channel oscilloscope (1MΩ, ±25V, differential, 14 bit, 100MS/s, 5MHz bandwidth);
• Two channel arbitrary function generator (22Ω, ±5V, 14 bit, 100MS/s, 5MHz bandwidth);
• Stereo audio amplifier to drive external headphones or speakers with replicated AWG signals;
• 16-channel digital logic analyzer (3.3V CMOS, 100MS/s)*;
• 16-channel pattern generator (3.3V CMOS, 100MS/s)*;
• 16-channel virtual digital I/O including buttons, switches and LEDs –good for logic trainer applications*;
• Two input/output digital trigger signals for linking multiple instruments (3.3V CMOS);
• Two power supplies (+5V at 50mA, -5V at 50mA).
• Single channel voltmeter (AC, DC, ±25V);
• Network analyzer – Bode, Nyquist, Nichols transfer diagrams of a circuit. Range: 1Hz to 10MHz;
• Spectrum Analyzer - power spectrum and spectral measurements (noise floor, SFDR, SNR, THD, etc.);
• Digital Bus Analyzers (SPI, I2C, UART, Parallel);

Morning gents,

I've just finished the build of the Wolverine amp (solid state) and I'm looking ofr a new project. I'm currently running a Dietpi with BubblePNP (dlna) and Qubuz which feeds my standalone S.M.S.L. Sanskrit Model 3, 10-th edition using the USB input. This DAC directly feeds into the Wolverine. The Wolverine drives to (ancient) KEF Reference Model 3's .The only control I have is the volume on the DAC.
My questions are these:

• Is it worth building your own DAC from a sound quality perspective?
• Are there diy DAC's worth building?
• Any suggestion on digital controls? DSP?

thx in advance

Willem

I considered putting together a Purifi amp, but after listening to my SMSL class D amp for a while I'm not convinced class D is the way to go.

Then I considered getting the Benchmark AHB-2, but thought the price is a little steep.

Then I considered Holton amp modules, until I read the horror story about the company.

I wonder, if there are any other high performing class AB amp modules out there?

If not I might have to build a Pass F5, but it is class A.

And knowing myself, building an amp from scratch like the Honey Badger or AMB Beta 24 might never get built.

Hello everyone

I haven't had any experience with switching power supplies and I’m not sure what is a normal behavior at the voltage output of my Connex Electronic SMPS300RE. It is a version with a dual voltage output and a dual aux voltage. It should be the current version of the power supply unit, but it looks a bit different to the pics on the manufacturer website.

So what do you think, can a defect be assumed if the positive voltage drops immediately after disconnection from the mains, but the negative voltage drops slowly?

There is a little difference of 0.5 volts between the positive and negative voltage. The dual auxiliary voltage drops evenly and slowly on the positive and negative side.

I would have assumed that either the output capacitor of the positive main voltage is defective or that there is a short circuit. Does anyone have any experience of what is the "normal" behavior of such a switching power supply?

Regards

Josoeff

Hello every one

can somebody tell me the chip amps that works on single 12vdc

I used to read somewhere that when establishing a bi-amp configuration, the power could be calculated to new power, i.e., a bi-amp system employing a 60W mid/high amplifier and a 60W woofer amplifier can equal or exceed the performance of a single 150W amplifier driving a speaker through its passive network.

Is there a formula for calculating the new power when setting up a bi-amp configuration?

e.g., employing a 70W mid/high amplifier and a 105W woofer amplifier can equal or exceed the performance of a single .... Watts amplifier, or employing a 65W mid/high amplifier and a 120W woofer amplifier can equal or exceed the performance of a single .... Watts amplifier.

Hi. is there somebody who has a schematic for a Sunfire model D-8 circuit board?

Hi, what temperature do you use when solder parts in PCB? I use 350 C / 662 F.

WBT say 250 C / 482 F.


Frank

I have been looking to design an active elliptic filter for a dac project that I have been working on to speed up audio at a specified multiplier. The dac can speed 44.1 audio all the way up mhz sample rate ranges. I was wondering if anyone can recommend a tool to help design an active elliptic reconstruction filter?

Previously I have attempted to implement a passive elliptic filter stage using the rf-tools elliptic filter calculator but struggled with the very specific inductor and capacitor values required for said filter. Implementing a passive filter multiple times as required for the project would be a complex undertaking so I'm thinking an active stage would be easier to implement and also be more repeatable when needed? If my target sample rate was 2.8224 mhz images will start appearing at around half of the sample rate so I'm guessing a filter utilising a 1.3mhz cut off would be sufficient to suppress the dac images? My maximum theoretical frequency would be around 1.28mhz. If anyone has any pointers I am eager to listen.

Does anybody know where I can get a schematic for the LINX Nebula intergrated amp,as I'm having trouble with the 12v supply going down after about 15 mins of use,
any help would be much appreciated.

thanks malcolm

Alarming how long I've had these kicking around.

Either way £100 inc UK shipping for a 48pcs

Hi everyone, I bought this nichicon ka capacitor, I see this capacitor has a curved shape like the picture, and capacitors from reputable websites have straight legs, do I have to buy fake capacitors or are the curved legs? Really made to order

Someone asked me how I fit the Jung-Didden regulators into this box...which led me to look at the phono section.

The two input transistors that Crown used, 2N3895A and PN4250A low Rb, the LM301A opamp is truly ancient. I hadn't seen this type of phono-pre, but only started seriously dabbling in phono pre and RIAA comp networks in the past decade or so!

SY isn't around to throw bricks at this Crown design. The compliance, in simulation, to the RIAA curve is very good. Will have to see if my actual living model is equal to the simulations.

Looking through a lot of relatively new circuit designs of valve amplifiers, the Constant Current Source takes almost all the leading position. Except those used in Filament CCS, almost all other designs are Cascode ones.

For example like this, the M3 and J1-J4 formed a Cascode CCS.
If we set it at 10mA and using DN2540 at M3, the FET at J1-J4 position could only get a Vds even below 1.5Volts, which can't drive the FETs into saturation area.
If the lower side FET can't go into saturation area, how could it deliver a constant current?

These new SiC JFETs entirely eliminated such problem. The Vgsoff of these transistors is typically -9Volts, which means you'll have over 8Volts for the lower side.
I could say these SiC JFETs fully "liberate" the lower side conponents, providing a better working condition(Over 8.7Volts for 25mA) comparing with traditional Depletion MOSFETs such as DN2540(lower than 1Volts for 25mA) and IXCP10M90S(About 2.4Volts for 25mA). Even LM317 could be used here for a higher current accuracy.

I've bought some samples of the 650V 80mΩ version, and give it to my friend replacing DN2540 in the Mu Follower design. Now his only remainging question is what to use at the lower side😀.

The problems of the SiC JFETs are also clear.
The capacitance is the biggest one. The Rdson=80mΩ version has a Crss of 88pF, while the Crss of Rdson=400mΩ version is 18pF. It's much higher comparing with DN2540.
Maybe packaging the UJ3N1701K2 is the ultimate solution 😵


Here's the curves I traced with DTT-X of UJ3N065080K3S.


These two are the characteristics of UJ3N170400B7S.

And I also managed to trace the output characteristics in high voltage area of UJ3N065080K3S with etracer. Since it's not easy setting, I've only scanned the curves when Vgs=-9.0V.
Notice that Vgs should be provided externally and previously, because the normally-on state of JFETs will trigger the Short Circuit Detection of etracer.
It's not as horizontal as DN2540, so Cascode is necessary.

I have, absolutely no idea what could be wrong with this. Can someone help me out? Thanks in advance

Hello everyone. I'm thinking of building a pair of Dayton BR-1 speakers.
I would be interested in your opinion on whether to do it with your original crossover or with the crossover modification proposed by Dennis Murphy.
The drawer would have the measurements of Paul Carmody's Classic II.
The position of the drivers would be respected according to the original BR-1.
The duct would be later.
Another question is if the tweeter in Murphy's crossover mod is the Dayton DC28F-8 or does he have another.
First is original and second is Murphy.

http://murphyblaster.com/content.php?f=pe_br1.html

SOLD

Thanks DIYAudio!

Hello everyone,

I just bought a pair of old KEF 103.4 speakers from the 90s. Unfortunately 1 of the speaker sounds completely muffled. I thought the ferrofluid of the tweeter had to be replaced but the problem seems to be the mid range driver. The driver is a b160 sp1278 and it seems that the membrane is somewhat stuck. if I apply pressure on the membrane it does not move freely. It feels like there is a lot of resistance (the other speaker’s membrane is much more flexible and the speaker sounds fine). It also seems there there is a damage. I attach a video where I try to visualise the issue Login to view embedded media
I would swap out the driver but I am not able to find any. Does anyone have a clue if there is a way to fix this issue? Any suggestion is highly appreciated. I really don’t want the speaker to end up in the landfill so I would like to repair it.

Many thanks!

Alberto

https://www.labmanager.com/moth-win...g-wallpaper-in-sight-after-breakthrough-28276
https://www.bristol.ac.uk/news/2022/june/moth-wing-inspired-sound-absorbing-wallpaper.html
Speaker cabinets? Room treatments certainly.

Does anyone have a sub replacement part number for the channel selector switch on the power 650 amplifier

At the request of those who are helping me with this issue, and for the benefit of all members of the community who may someday experience a similar problem, I am going to gather the details of this "case" in this new thread...

The circuit in question is the TSE-II SE amplifier with 5842 input tubes and 300B power tubes.

The schematic is attached to this post.

The power transformer in this case is:

https://edcorusa.com/products/xpwr178-660v330-0-330-200ma-6-3v3-15-0-3-15-6a-5v2-5-0-2-5-3a

I measured DCR as follows:

• Primary winding: 1.75 ohm
• HV secondary: 35.3 ohm and 36.8 ohm

I did use this choke in place of R4:

https://edcorusa.com/products/cxc125-10h-200ma-10h-200ma-choke

Its DCR is 75 ohm (vs. the 150 ohm R4).

C4 is a quality 47uF 450V electrolytic capacitor.

(A 5AR4 should be able to handle a 60uF input capacitor, according to the datasheet.)

C5 is a quality 150uF 450V electrolytic capacitor.

I have the following motor run capacitor in parallel with C5:

https://www.digikey.com/en/products/detail/kemet/C870CG36100AA0J/6556371
(100 uF Film Capacitor 470V Polypropylene)

hello everyone
I have a speaker in the works that I’d like some input for
Im quite new to diy so it’s quite a ambitious project
The driver I have are
Beyma tpl 200h
Ae td10m 4ohm ( on order )
Ae td15h+ 4 ohm

The front end will be mini dsp flex so it will be a active speaker
I’m planing on using 3 pairs of stereo audiphonics Hypex ncore amps

The main problem for me is the size, I want to keep it as compact as possible

I was thinking of either having the 15s in there own chamber maybe sealed
And then either having the tdm and Tpl share a chamber
But I could also remove the rear of the tpl so that would need it’s own chamber

I was either thinking of having the speaker 12” wide for the td10m, so it looks slimmer from the front
And have the the cabinet 17” deep for the 15” drivers to be side firing

Or have it 17” wide and the 15” face mounted but make the speaker 12/13” deep

So sealed or ported for the td10m / 15h+
At the minute the td15h+ are in small sealed boxes with about 750w each to them

I was thinking of being able to get around 60 litres sealed in the 3 way

John recommended ported for the td10m

The other thing I’d like to do is cross the td10m as low as possible to the td15h+ with some shallow slopes to help that 100hz area

Help Sizes slopes stuffing cabinet design etc would all be appreciated

Thanks in advance

Need to replace the left front speaker terminal. The plastic broke and now I only have the rear channel.

Hi all-

I am excited to report I have finally found and purchased a pair of Beveridge electrostatic speakers. I am NOT excited to report they are in rough shape and do not currently run; they need significant work. So let's start a conversation, shall we? I'm happy to hear from anyone who's been there and done that.

They are model 2SW-1 but the separate woofers are gone. The amps need a significant amount of work, time & money to fix. Before I do all that I first want to verify the health of the ESL elements, to the extent possible anyway. So let's start with them.

I have not opened the cabinets yet but the capacitance measured at the banana plugs is ~2,500pF from stator-to-stator, and it's one-half that from the membrane to any stator (~1,300pF). Both cabinets measure the same; I take that as a hopeful sign.

So... what do you think? What testing and inspections should I be doing here? Any input is most welcome, these are unique in many ways and I could easily be missing some important detail (or several 😀).

Many thanks.

I have a shelf of old Fender transformers. Some are from the Fender/Panasonic collaboration many years ago (they made power amps and larger scale mixing consoles). Some are older transformers for tube amps. Small ones are probably for reverb tanks? Most of these are NOS (new old stock).

I'm moving and these need to go, hopefully to a good home. Contact me if you're interested in any of this.

Location: Chicagoland Illinois USA

Additional pics.
https://www.teedy.audiovidual.com/s...606f7b7e/c69fe0e0-b976-4675-8937-313180f0d5cf

Hi. I would apprechiate any help on I guess, quite basic question. Is the dc offset measuring procedure the same for integrated and power amp, or do I have to do something diferent when checking power amp offset? May I just power it on with no preamp and speakers conected and measure offset on sp terminals, or... ? Thank you.

Im parting out my Icepower 50asx2BTL mono blocks.
I have 2 Modules available, real BTL not SE converted. ASKING 75 SHIPPED EACH USA
Ghent Audio MonoBlock case 60 shipped Like new still
Ghent Audio RTX Module have 2 of these as well. 65 shipped COnt USA.

hello, i picked up a fostex vf80 recorder from reverb.com,not knowing it didn't have the build in CD burner ,so i found one CD 1-a burner on eBay,installed it in the unit,and found out it was not plug and play, you have to upgrade the software as well, the software is fostex version 2.0,i know this is a shot in the dark,but if anyone happen to have a fostex version 2.0 for fostex vf80 recorder,and can put it on a flash drive/cd i am willing to pay for it as well as shipping,this maybe a long shot,but without the software the installed CD burner wont work,thanks

Hey everyone!

First time posting here. I have owned and used a pair of KRK Rokit Classic 5s for close to 8 years now. I always really enjoyed their sounds, not knowing any better. It has 'good enough bass extension' and sounds alright.

I have been meaning to upgrade my system for a little while know. I would like to go the DIY road because I want the absolute best bang for my bucks. I have some experience when it comes to DIY, enough to undertake a nice build, going slow and steady.

I'm somewhat on a tight-ish budget, and wanted to explore my options. The speakers would be placed in a room that is about 14/16 square meters, on bookshelves.

I listen to jazz and electronic music mainly so bass extension and good detail retrieval is important for me. Most of all, I'd like for the build to truly feel like an upgrade from my current studio monitors.

I have about 400€ set aside for the build. I've been looking everywhere but it's hard finding good, recent recommendations, and I always end up clicking on dead links or seeing recs from 2011. I was wondering where the best value lies nowadays.

I don't mind sourcing individual parts vs. getting a kit. I have access to some woodworking equipment but would prefer something straightforward vs. some odd, complex slanted cabinets. Of course, if a complex cabinet is what's standing between me and an awesome speaker, I'd be willing to go the extra mile.

I would chose an amp based of my choice of build. Budget for that is around 200/250€. DIY is alright as well.

Thread here. https://www.diyaudio.com/community/threads/recording-studio-power-amplifier.401675/
Gerbers are still available for personal non commercial use for the next 24 hours for the early birds for the rest of us RSVP

http://frugal-phile.com/boxlib/pensils/Pensil103-plan-300114.pdf
http://frugal-phile.com/boxlib/pensils/Pensil10p-plan-140613.pdf

dave