Having issues with a Hitachi V212 Scope. Power LED is on, but screen is completely dead. The usual low voltages are all present, including CRT heater, but I'm guessing there is no power to the CRT grid. As I don't have High voltage test gear, is there a safe way to test and track down the fault.

Many thanks😱

John O

So bit of background, working away applying some eq to the subs n speakers for a new listening room that has been built by a close friend. It is sounding ok above 190hz as that seems to be the Schroeder frequency for the room. No doubt it will need room treatment but enough on that.

My question relates to 200hz and below, in rew automatically checked is allow narrow band Q below 200hz. Am I right in saying that the lower in the frequency range you are the narrower the Q and the higher you are in the frequencies you desire a wider Q?

Hi there!

I spent the majority of my life programming software for corporations, trying my best not to be evil, but you know...corporations! Now I'm in my fifties and have a lot of time on my hands. I'm taking this opportunity to learn electronics. It's interested me since I was a wee lad, but I finally have both the time and a small amount of discretionary funds to slowly buy components.

I love listening to music, and am making some efforts to be able to play an instrument at times.

I want to build an amp that will get me through the zombie apocalypse by being well documented, made with easily sourced parts, and be repairable with moderate skills. I'm learning on existing amps from the 80s and 90s for now. I'm already OK with digital electronics, but that stuff is easy compared to the analogue stuff that seems to need a whole other part of my brain that's been on holiday until now.

Thanks for the invite!

3D printed feet for the Zenductor II (and can be used with original Zenductor for that matter).

The goal was to both move away from the metal hex standoffs (both slippery and scratchy) and make a wider front post/foot for the tripod configuration (make it less tippy). The fact that it looks adorable is just icing on the cake 🎂

A standard M3 nut is inserted from the bottom (use a long m3 bolt to press it into the pocked) and a M3x10 (or longer) bolt is used to then secure the foot to the board.

I printed solid with TPU, but PLA would also likely work (its not squishy like TPU though).

If anyone would like me to print these and send them to you with the necessary M3 nuts/bolts, I'm happy to do that for $10 shipped within the continental USA.

Hi there. I’ve have a passion for vintage guitars, amps, vinyl, and hifi gear. I’m forever trading, tweaking, and taking on projects. I look forward to this site and all the cool people here.

Kelly

Ive been let down by an ebay seller who has left me in the lurch and i want to reassemble my guitar amplifier thats been on the bench for weeks now.

Im after the following values in 5% tolerance:

2x 10K 2W
5x 10K 0.5W
75K 0.5W x2
2.7K 0.5W x2
15K 0.5W x2

Im pretty sure thats all I need to complete this but can confirm later.

Hi there, im interested in diffraction horns, listening bars and cultural spaces. Im looking foreward to build a small cutom hifi-club-soundsystem.

Hello Everyone,

I am currently helping a friend with his cranky NAD T 751 Receiver. The left channel is very quiet (speakers and headphones) on all inputs. I assume that the problem is on the Front Amplifier board, but I have been unable to find any "known problem" issues with this board or amplifier. R518 on the attached schematic (left hand side) seems a bit discoloured and is running quite warm (> 50 C). Otherwise, there are no obvious issues visually and it seems that this board is quite difficult to remove.

Has anyone out there had experience with a similar problem in this (or similar ) amplifier? I would greatly appreciate any suggestions you might be able to provide.

Thanks,

Andrew

Hello all, Does anyone have experience with programming a new processor after replacing the microprocessor like Denon AVR-X....
If anyone has done this before can you please help me?

I have a DENON AVR-X3400H failure microprocessor

According to the service manual, after changing the chip, the main software needs to be loaded, but there is no information on how to do it.

Please help me.

Hi folks, I'm looking for a 2.1 digital amplifier that will let me select between two different RCA (or 3.5MM) inputs.
Must also have bass blocker for the stereo speakers and adjustable subwoofer output/frequency.
Wanting to stay under $100.

Any suggestions?

I found the Dayton Audio DTA-2.1BT2 but nothing else so far.


EDIT: I didn't find anything else in my price range, so I ordered the Dayton.

Hay all, I know that these are falling out of popularity, but they’re are definitely uses for vacuum tube meters as many of you know. Like the ultra high input impedance. I like having as modern and accurate equipment as I could possibly afford, looking at some 6-1/2 digit Keithleys, Agilents, and Tektronix bench meters, but if I come across a very good priced vacuum meter that is in good condition when I attend local electronic swap meets I will grab them. Last year I grabbed an HP 410B which I fully restored, replacing all the capacitors, tubes, and installing one percent resistors in place of the carbon comp. After the alignment, this thing is dead on accurate, I see why this meter has the hype behind it.

Onto my questions for help. This year I picked up an HP 412A. Like the 410 it got a full recap, 1% resistors, cleaning of controls, and I picked out all brand new tubes. The two regulators measured good, looked in my stash and found NOS JAN 12AX7, 6AU8A and 6X4, they all tested very strong and were installed.





Just some pulmonary testing measuring some DC voltages on the different input levels showed me that it was actually already very close to being aligned. I’d be very happy with leaving. It is where it is with measuring DC, but if I were to just nudge the Neal, it would be perfect, and I’m talking maybe half a needle width.

The first thing to adjust is the hum balance, and I can’t even get that, getting stuck on the first thing lol.


It says to attach a scope probe to the amplifier output on the back of the meter.


Have the meter set to volts and it says to adjust the hum control for the minimum 10 Hz signal on the scope, at least that’s what I think it is saying. I have the scope settings pretty darn low, 2mV/div or 5 mV/div. With where the meter was I wasn’t seen anywhere near 10 Hz. it was fluctuating quite a bit and the several kHz. I was able to trigger on the signal, but it was moving around a bit.



I started adjustment of the hum balance and it started adjusting the waveform I was seeing. I got the frequency closer, but it was jumping around from as low as 7 Hz up to just about one kHz. it was incredibly difficult to get it to a point where I thought it was lowest.


Am I doing this incorrectly? I did notice that when adjusting the hum balance that it greatly affected the zero point of the meter. So after making an adjustment on the balance, I would have to go to the small screw right below the minor to zero it. Is that movement from the zero point noise? Meaning would it be best to adjust for the lowest point on that meter, and that would be the lowest hum point? I’m guessing that lol.

Would love some pointers if anybody has them, thank you. Bring this beauty from yesteryear back to life and let it feel useful again.

Thank you,
Dan

I'm in the process of building an Aikido OTL headphone amp and thinking of add a pair of VU meters, just for the look.

The driver board I intend to use is this one: https://www.ebay.com/itm/1668490787...HbusGwtRI-&var=&widget_ver=artemis&media=COPY

My question is whether I should connect the meters to the RCA input (fed from a 2Vrms output DAC) or headphone output?
And of course, most common question, does these meters affect the sound in any way?

Thank you in advance.

Hey you builders!

Planning to play some music on the streets with some of my pals, i have been looking for a matching portable PA. Now recently people started bringing portable tower PAs (such as the JBL IRX one or the more expensive JBL Eon one mk2) to the gigs in my town. I find these all-in-one solutions really practical, if there were not the "relatively" poor sound (WHERE ARE THE MIDS?), regarding the high price. So i am planning on building a better or at least cheaper one myself. To eliminate the mid gap i thought of building a 3-way-system, where each speaker is in its own enclosure. A fourth enclosure would house the battery, crossover and mixing console. The goal is to be able to assemble them easily at the spot. Having some experience in building speakers, but never even tried a project as complicated, i'd like to post my thoughts and of course building progress here, so you guys can give me your opinions, tipps and tricks. 😉

My Requirements:

• Portable (as in weight, size, etc.)
• Battery powered
• 3 way
• rms between 150 and 600 W (i know its a lot but that leaves me with some room to play with)
• 8 channel mixer (Mono out)
• amp integrated either in the mixer or after the mixer in the same housing
• not exceeding budget of 800CHF (ca. 920 USD)

What i already have (if possible i will work with these things):

• 2 x 20000 mah 48V Battery-Pack (probably for either having a backup or in parallel)
• lots of baltic birch 12mm strength (would be cool to achieve a lightweight but sturdy construction)
• A great workshop (suited for wood, metal and esd-sensitive soldering works)
• Lots of in- and output parts for audio connections

Shopping cart:

• Woofer: B&C 10HPL64 16 Ohm or B&C 12 PE 32 (More better and more Expensive)
• Mid Driver: PD.615C002
• Tweeter: Eminence APT80 V2 (I have another one lying at home, i don't know if its of any use, i'add it here, when i'm at home)
• PCB and remaining parts for the mixing console
• PCB and remaining parts to split power of the batteries to the mixer and amp
• parts for the crossover ( or would something like this work as well?)

What do you think about this idea? I ironically do have a little experience in designing crossovers, but way less in buying speaker drivers. So i am open for alternatives and opinions! Sadly i am, as of right now, unable to find any schematics for a mixing console/power mixer. analogue or digital doesnt matter to me. anyone got a tip? i might as well buy and install a wonky solution like two of these with the input channels altered and put a honey badger amp after them.

Thanks for your opinions and ideas!
TheBigBlubb

Hi,to all. I'm new to the forum, however I've read many post for quite some time; I decided to join in.

Hello, newdy into the DIY class A world and am wanting to maybe go full active on my Carver Amazings using a class A amp(s) to power the ribbons. The bad thing is they are very power hungry and are only 1.5ohms. I want to do a pair of mono blocks and have been trying to research if or which Pass clone would be best. From my research the Aleph 2 seems like it way work. In the manual it state it’s 100 watts@8, 200 watts@4 with a maximum of 400 watts and can play into any load down to a dead short. How true is this and will they be able to play a 1.5ohm load? Any other suggestion's or advice would be greatly appreciated too!

So I want to make a valve audio preamp, but need a way to generate clean high voltage DC for the plates of my tubes. I started with rolling my own boost converter which worked well, but was unable to reach my desired voltage (about 200 V) as it was to much to ask from a single stage starting voltage of 12 V.


After some searching I came across this circuit which uses a step down transformer in reverse:



This looked nice and simple and began working on my schematic:


I added a MOSFET 'capacitance multiplier' as I want my supply to be as ripple free as possible, as well as the voltage climbing slowly will help in the following sections. C2 and C3 are probably over-kill but I have them in stock so may-swell.


The regulator is to power the filaments of two tubes and is tested and works great. My tubes only allow a 6.3 V connection.


So my first step down transformer is an enclosed 240 Vac primary, 12 Vac secondary, 36 VA. Picture here:



And my second 'step up' (backwards) transformer:



I have tested the low voltage side and regulator circuit, which seems to work perfectly.

I need about 220 V that supports a current draw of 20-30 mA.

My first question is are these transformers ideal for the application? giving that Transformer 1 gives about 13.5 Vac loaded with 1amp. how much can I expect on the high voltage side?

I plan to use large 470 uF 450 V capacitors (C2, C3) overkill I know. Is inrush current a concern on the coils?

I'm guessing the 0.01uf capacitors in parallel with the bridge rectifier diodes are to suppress EMF and high frequencies. Are these worth including?

For grounding, I plan to connect the grounds of the high voltage and low voltage side together and connect to the chassis that prevents the chassis becoming live. Is this the right approach?

I know this is a few questions rolled into one, but as my first high voltage project I want to make sure I get everything right. Thank you!

A little photo report:

Theme and Variations on a BA-3 driver stage and BA-1 follower output stage

Before soldering this , thought it might be good idea to run it by the experts .

For the voltage gain driver stage , I have some

• 2sk246 BL and 2sj103 BL jFETs
• Exicon ECX10n20 and ECX10p20 lateral MOSFET's ( Ciss = 500 pF )

The Idss ~ 7.0 mA for the jFET's .
Is matching of the lateral MOSFET's required ?

With the jFET's biased at around 4.2 mA to 4.7 mA is this enough current to be able to effectively drive
the lateral MOSFET's . Is there a cook book equation people use for this ?

The lateral MOSFET's seem to be quite content with a bias = 100 mA

For BA-1 follower output stage , rather than trying to match up 6 x IRFP240 's MOSFET's
thought it would be easier to use singles of IXFN180n10 MOSFET's ( Ciss = 10,900 pF )

So here are the schematics , any advice would be appreciated before the soldering iron comes out .
( Or the hammer )



.

hello!
please note that minidsp does not have a return policy and their products are shipped from china! you will pay huge tarrifs and have no way to return a broken product or get a reship from them! stay clear, use a local importer!
cheers

I have surplus 13 pcs of these high current - too hot to handle critters. They will be sold at $15/pcs, or exchanged for their lower current brethren, the 2SK147BL.

I prefer selling as a lot, but they can also be matched. At an additional cost. If so, please state your requirements in a PM.

Shipping at cost.

R

Hi

Does anyone has the schematic for this amp. This amp uses power transistors unlike the other AVT150H which uses the TDA7293 as the power IC. Please assist.

Thank you.

Western Pennsylvanian with interest in Pittsburg Steelers and home audio.

Hey team,

I remember there being some chatter about this, but alas my searches havent been too successful. please do point me anywhere if this is already discussed.

Planning to build an outboard power supply (dual mono, 2x 400 or 500va trafo) to power various projects - Aleph J, F5, F6, etc. and beyond. Logically, a +/- 24V output is the ideal.

I had thought originally to put 2x UPS boards within the power chassis and send umbilicals up. They would sit close to each other the two, but the idea is a modular pass system so we can enjoy various builds without having to invest in redundant parts, larger chassis, etc. etc.

Thanks in advance.

Hello everyone,

I bought a Philips CD 150 to make some modifications and see how far it's possible to improve the sound of these old devices. I have already replaced the op-amps, the power supply diodes with Schottky diodes, replaced the old capacitors, and done a DEM reclock of the TDA1540s. In addition to that, I would like to supply a dedicated power source to the SAA7030 and add a new 4.2336 MHz clock. The problem is that I understand the SAA7030, like the SAA7220, can introduce jitter into the clock signal before it enters the TDA1540s.

If I’ve read the service manual schematic correctly, the clock injects 4.2336 MHz into the SAA7000, which then redistributes the frequency to the SAA7020 and also to the SAA7030. Then, the signal passing through the SAA7030 is used to feed both TDA1540s. In my opinion, there shouldn’t be a problem continuing to power the SAA7000 to then feed the SAA7020 and the SAA7030, but it would be necessary to provide a dedicated clock to the two TDA1540s to avoid supplying a frequency from the SAA7030 with too much jitter. I also plan to power the new clock with its own power supply. Has anyone already done this and could offer advice on what and how to do it?





Here is a link with some explanations I found on internet : Clock mod TDA1540

Thanks by advance for your help guys

Symmetric CFA with EXICON 10 Watt Class A output.
The design gives dominant 2nd harmonic.

Hi folks, this is my first post here. I've toyed with building speakers in the past, but never got around to it. While this isn't it either, I do think I'm a bit out of my depth and kindly ask for some help or guidance.

I got ahold of a beautiful dali helicon center speaker, but with one mid/bass driver dead. I took it out and measured the impedance with my multimeter and sure enough it's in the KOhms range.

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Part 1: Figuring out if the rest is good

Apparently the other drivers should work fine, but I'm not exactly sure how to figure that out. I've disconnected and measured them and they seem to be ok:

• Ribbon: 8.5 Ohm
• Dome: 5.8 Ohm
• Mid/Bass #2: 6.4 Ohm

Is this enough data to confidently say they should be fine?

Part 2: Finding replacements

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From what I've managed to gather the Helicon drivers should be very similar to Vifa M18WO (not sure exactly which model, does the measured impedance imply it's the 6-Ohm version?). The issue is, those Vifas are decades old as well, so finding them doesn't look like it'll be an easy task.

How should I go about finding a newer, in-stock model that might be a close match? I'm not looking to get it 100% identical to the original, but definitely hoping to get close, at least on a quality level. Would like to match performance as much as possible as I'm using the Helicon 400 towers as my mains.

What numbers should generally tell me if the driver "fits"? Physically, sure, I can figure that one out (I hope). But electronically, sonically? That's where I'm lost.

Also, is it okay to replace just one of the mid/bass drivers or should I go ahead and replace both?

Part 3: Tweaks

Ideally the replacements work fine and that's that. But if there is work that needs to be done on the crossover, I guess I could try. I know my way around a soldering iron, at least for basic operation. I have a vague understanding on what the crossover's elements do, but not enough to comfortably tackle this on my own. Is it bound to come to that and if so, how should I go about it? The crossover is definitely hard to reach, so it's the part I'm least excited about. 🙂

Edit: I didn't even notice it before, but there is a big black spot on that crossover. Is it safe to assume that something burned? How can I go about solving that puzzle?

I took some pics in case they might come in handy:

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My question relates to 200hz and below, in rew it is automatically checked to allow narrow band Q below 200hz. Am I right in saying that the lower in the frequency range you are the narrower the Q and the higher you are in the frequencies you desire a wider Q?

This information I have gathered from audio engineers/mixers would the same apply to the room?

Hello!

I'm having a strange issue with a Coda Csib integrated amp. The bias either drifts drastically up or drastically down on one channel or the other. it seems to be only one channel at a time acting up and only after a while, at first they track pretty closely to one another until the amp is nice and warm. A lot of components seem to influence bias even when I just put my finger on and without a schematic it's really hard to track down. Does anyone have any info on this issue on this particular model or have a schematic ?
I did get an answer from coda on what bias setting to aim for but no help with the actual issue or schematic.

Hope someone out there can help me get the strange out of this one 🙂

Hi,

I have a mixing desk (Studiomaster 16:16:2) and I need some help identifying the capacitor types. I've attached a photo of a channel strip (not mine, from another thread). I can see electrolytics and ceramics on there but I don't know what the grey rectangular ones are.

https://www.diyaudio.com/community/attachments/100_4149-jpg.184679/

Thanks,
James

I am asking for a friend who is designing a three way 10/5/1 Satori speaker.
He is measuring Q with a view to the size of the midrange enclosure. He is within 5% of the SB parameters published.
The question is how much Q should be designed for, and why. 0.5? or maybe 0.75?
What would be the differences and how would this affect the size of the enclosure?
Thanks in advance; I'm a newbie here........
HD

Hello diyers,

I would like to build a DAC based on 4x TDA1387 but I don't know which parts and sections I'll need, since I'm starting to understand how a NOS DAC actually works. There are some good quality ready-made boards available online, but I need to build it very small, minimalist style for a portable application, so I must build it from scratch.

Digital data and MCLK would come via I2S from an ARM MC (Teensy4).

My initial question is which sections this DAC should include. To my understanding an LPF and a voltage to current (VI) converter are needed at the output of the DAC paralleled ICs, the latter can be an opamp or inductor network. Which other sections would I minimally need, provided PSU and MCKL are already there? I think a TTL IC might still be necessary for it work in slave mode, but still don't understand it's function so I'm not sure about it.

I'm trying to get a broad view on what does it mean to embark in this project. I don't need the best quality ever, but that it works decently for monitoring audio to be recorded. If anybody has seen a circuit diagram for this DAC with components, that would be very helpful. There is a 4x board around but it's USB and undocumented. I haven't found any diagram on the 8x chip I2S board neither. Any contribution will be highly appreciated.

Regards and cheerful Christmas (specially for those who celebrate),
Domingo

Hi
Does anyone have a supplier for replacement tweeter coil for celestion DL8.
So far I can only find Chinese suppliers.
Ta.

Ucd400 Q & A

Hi,

I thought it an appropriate time to start this thread.

I've read before there were two versions of the UCD400 being develloped at the same time.

Which is currently available, will there still be another version comming out soon, if so what can we expect on it should we wait that we won't find on the currently available version?

Exactly what kind of protection does it feature? Overcurrent? DC? etc.

I've a question about the order form as well but I'll ask that privately in email.

I'd like to comment on the picture used on the webpage, it's very dark, especially the one that pops up when you pass your cursor over it 🙂

Do the drivers for it feature adaptive dead time?
Are there any other ways in which it differs from the UCD180, filter, input..?


What op amps does it use in the input stage?

That's it for now, thanks alot.

Chris

I’m rebuilding a HP 412A and nearly done. There is a Sprague 192P film cap that is in the switch and in a place that would be an absolute pain to swap out.





This is what it looks like


It’s a 200v rated cap and I’m guessing it doesn’t see a whole lot of voltage I the switch.



So not being stressed, would you think this cap would be perfectly fine? Or are these well known to degrade like bumble bees or black beauty (well the paper ones) and I should take the 2 hours to remove it and swap it out? I know there are polyester films that do go bad like the flat grey ones used in Marantz, those are notorious for failing.

Thank you,
Dan

Hi all,

Any assistance appreciated. I like overall the drivers here and would like to build with them, but I can't seem to come up with a basic crossover to match them up passively.

I'm thinking of crossing around 300~400hz, or even 500hz with the planar wide band driver. The low end will be a bass reflex cabinet with the two woofers. Was thinking of doing the two woofers in series (8ohm) dual opposed in the cabinet (tower) with a 28~35hz tuned port.

Goal is a stereo tower pair. Crossing around 500hz maybe? 1 wide band, 2 woofers. A WAW/FAST at heart I suppose? Bass reflex towers tuned to 28~35hz range. Goal is to be 4ohm~8ohm range as seen by an amplifier. Will only ever give it about 100w total. Ok to not be flat, but prefer it to not be super bright so was trying to calm down the top end with compensation. Baffle width total will be about 12 inches I think.

Drivers:

Planar wide band:

https://www.parts-express.com/GRS-PT6816-8-8-Planar-Slim-Tweeter-8-Ohm-272-128?quantity=1

Was thinking crossing anywhre from 300~500hz range?



Woofers (was thinking 2 per tower in series):

https://www.parts-express.com/GRS-1...-Excursion-Subwoofer-4-Ohm-292-818?quantity=1

Maybe take these up to 400~500hz range?



I have loaded these into X-sim to experiment. But I'm really falling apart on it. This is my weakest point in speakers... passive x-cover design. So any help super appreciated.

Xsim attached with drivers pre-loaded for any help to make it easier and less tedious to enter info. 🙂

I keep getting nasty cancellation or silly low impedance. It's bad. Real bad. I'm bad at this lol.



Very best,

Hello,
I just got a Nad C3050 along with its BluOS-D card.
So far I enjoy a lot the vintage look, vu-meters and most of all BluOS streaming.



But I am not convinced by the sound which, although very neutral seems a bit thin-sounding, especially in the midrange.
Voices seem to disapear in the background, my previous Rega Elex-R had way more life.

I am considering swapping the internal Hypex UcD102 for a better module, as it seems to be plenty of space available.
(And I would like to avoid having a separate power amp. )




Which module would you recommend as an upgrade? Or is there anything I coud do on the UcD board to improve it?

So I’m looking to replace the drivers on a set of 80’s kenwood jl850 speakers. Obviously the old drivers are no longer in production and the ones in it need to be replaced. The speakers are fairly sensitive and easy to drive with about 125rms and 250w peak. The drivers are the old paper cone type on all drivers. I’m doing this for my grandfather who bought them new back around 86’ and wants to keep the original system. Not looking to break the bank here just give him some good sound that he lost. The tweeters are 2”cone , mids are 4.5” cones and woofer is 15” cone. I’m thinking possibly a premade crossover also since I don’t possess the skills to make one from scratch. Any and all suggestions are welcome here. Even if someone has any ideas about crossovers I would take them. Thanks to all who can help with this.

I know there are some folks who think that tinkering with a commercial product is sacrilegious,

Then there are others who want to dissect every part of the machine looking for weak points to upgrade.

I've seen a number of threads over the years of people tweaking their hardware to improve sonic purity by the replacement of certain parts with higher quality, or adding things which might help. Examples include regulators, op amps, wiring, capacitors, etc.

I've been listening to my MiniDSP 4x10 lately and I have a suspicion that there might be a few improvements possible. I noticed that the EQ filters aren't transparent. If I use a software EQ on my PC, I get nicer and more pleasant sound in the highs than if I use the parametric EQ of the minidsp itself... so right now I'm in the middle of efforts to get all the gains optimized so that minimal eq is necessary. I've also swapped out my system with a couple other dsp units from behringer and even run multichannel dsp in software on my pc. The results all sound different.

But this isn't a software question so much as the software got me thinking of how much improvement could be had if I open the box and start experimenting with what's inside.

Any minidsp aficionados out there who have ventured into hardware modification territory? What have you learned, and what would you recommend?

Thanks!

hello all, i hope this is the correct section for this thread.

i have this dbx m2 mic, trying to make measurements for my speaker project with REW.
the only info i can find about it here: http://www.aes.org/sections/pnw/pnwrecaps/2012/jj_jan/acoustic_meas_sys_101.pptx

the m2 response as shown in the pics attached has abig bump at the high frequences
is there an appropriate calibration file for it? anyone using this mic?

thanks for your time

Hi there. I recently bought a pair of 1958 Mullard tubes. One seemed to have slight defect in the top plate but I thought I’d try them in my phono stage. About 1 minute in BAM! It made a huge bang and fried my speaker.

Anyone ever have an exploding tube? You can see a chuck out of the top plate.

The 33/45 lever stopped working on my TD-145, and I found that the linkage which is supposed to engage the motor does not extend quite far enough to release the switch which engages the motor.

If I push outward a tiny bit on the linkage, the motor engages and works fine on both 33 and 45 positions.

I consulted the service manual, but I cannot find any mention of adjustment of this linkage. Is there some way to adjust it.

TIA

irf1404z and irf1404;
are they interchangeable?

Hello, I'm having a problem with my pass the x250 in the right channel, when I turn on the speaker it goes out and returns to its position and when I turn it off it goes backwards and also returns to its position. Can someone help me understand what it can be? Thanks a lot
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Next stage on my speaker build is to apply the veneer strips to the rounded sides. I picked up Rosewood veneer that is 1/42" (0.6mm) thick, non-backed. Beautiful wood.

Any recommendations for an adhesive to the birch ply sides? I have not worked with unbacked veneer before.

Thanks!

To broaden my horizon after use a tube based output stage, I’m looking to try some discrete output stages for tda1541a. Not pinned down on which one, just want to experiment a bit. Given others probably have tested multiple option and eventually settled for something, why not use what you have lying around… Shipping to Netherlands.

Examples:
Pedja
Sen/Cen
Others

Hello diyAudio family,

I require help regarding a project I am working on. I have a drive thru setup of my own where I have a base station microphone, the document says its a phantom powered microphone but with +18V, +18V and GND line instead of standard 48V phantom power. The current base station model doesn't support the recording feature so I decided to make my own. I am looking to tap the signals from the microphone and record them whenever a vehicle is present. I have done the tapping of the vehicle detect logic which is a simple relay logic turning on and off. But I am stuck in the microphone signals tapping phase. Can someone please guide me where should I start with? Your help will be highly appreciated.

Hello diyAudio family.

I am new here in this forum. My passion for audio engineering stuff has brought me in here.

Thanks in advance for any help or advice you can offer!

My speakers, Merlin VSM-MXr come with a custom hardware bass EQ that bumps them up +4db at 35hz and rolls of the bass more quickly. It goes between my yamaha CD-2100(high end SACD player/DAC) and my balanced 300B set tube pre amp. I'm integrating a sub for the first time via the second set of pre-out from the line stage and removed the EQ so that I don't boost and roll off the sub but when I ran frequency sweeps(REW, calibarted mic) before and after there was a noticeable drop out in the high freq starting at 2khz and peaking at -4dB at 10khz when I was running direct from CD player to pre-amp.

The EQ has a stable output impedance of 100ohms and I measured the output impedance of my CD player to be 530ohms(seems quite high but I verified it multiple times). I contacted Yamaha support and they verified that this seemed correct although it's not a published spec. I tried the XLR(measured at 1050ohms) out on the CD player but it was even worse with 15dB down at 10khz.

So it appears that my pre amp cannot handle the output impedance of the CD player causing high frequency loss. I measured the output voltage before and after the EQ and it's the same but if I remove the EQ the output voltage at with a 10khz sine signal drops from the preamp. The pre-amp is supposed to have an input impedance of 100,000 ohms. I verified using another source with lower impedance and without the EQ that there's no high frequency drop out. I also made a test tone cd and verified this happens both through the USB DAC and CD only output. This and the fact that the problem got worse with the higher impedance XLR suggest strongly this is an impedance based problem to me. To get the voltages and impedance numbers I used REW to generate a sine wave at various frequencies and used the USB input to my SACD player's DAC. Attached aligators to the RCA/XLR cables and used a multimeter(using a known resistor to load the output so I could calculate the impedance).

So basically I'm wondering is 530ohms very high output imp for a CD player and should a pre-amp with 100,000ohms input impedance struggle with that at all? I don't have the experience to know if 530ohms is abnormally high and should be looking for a problem inside the CD Player or concentrating on the pre-amp. What is generally the desired ratio for output/input impedance?

Is there a relatively easy way to measure the input impedance on the pre-amp to make sure that it is actually 100k Ohm as advertised? I'm suspicious that it may not be as I also tested the CD player with a Rotel integrated(with pre outs) which only has 47K ohm input impedance and there was no drop out.

I may be missing something obvious due to my lack of experience so I'm happy to have the assumptions I've made corrected.

Thanks for your time and consideration!

2 x 10F/8424G00, circa 2018, original shipping packaging, never powered. $180 + shipping

Ships from 78681, TX USA

I'm posing the question toward those who have completed a project already and would give their results at least 4 stars.

I'm looking for enclosure plans and a link to someone who sells the drivers in the mainland USA for a floor standing speaker with a Mark Audio driver.

It will be my first experience with a proper full-range speaker, and I'm intrigued by what little I have read about them so far, especially the commentary hovering around the Pearl Acoustics speakers. I'm not expecting performance to be quite at that level and although I could buy them outright, for me the fun is in the learning and experimental processes, and in building and finishing the enclosures myself. Gotta stay busy, otherwise retirement is just waiting for the grave, gnome-say'n?

Any advice?

This is a shared DIY project for non-commercial use.

The MA-3D is a 3 channel class D amp suitable for driving a BLWR172S-24-2000 or BLWS231S-24-2000 BLDC motor from Anaheim Automation. The amp is custom designed to work with only these 2 motors; any other motor connected to the output of the amp can permanently damage the amp. The BLWR series has a 4mm shaft and no mounting flange. The BLWS series has a ¼” shaft and a mounting flange that matches up with a Hurst 59 series motor. There are aluminum sleeves available from the RC boat market that will convert 4mm shafts to 3/16" props that will allow the BLWR series motor to work with 3/16" center bore pulleys ie VPI 600 RPM pulleys.

This is not a universal motor controller, it will only work with the 2 motors listed above. If you decide to use a different motor, you are on your own--do not ask me how to make it work for you.

The MA-3D is an amplifier section only and requires the SG-4 sinewave generator to provide the drive signals for each phase. The MA-3D board can also supply the SG-4 with the 12VDC signal needed to power it, so only one wall adapter is needed. The 15V 1A wall adapater included in the BOM powers both the SG4 and the MA-3D. The SG-4 must have firmware version 1.03 or later to work with these motors. V1.01 and 1.02 had a lower frequency limit of 40Hz for 33 RPM and 60Hz for 45 RPM. V1.03 reduces the lower frequency limit to 1.00Hz.

The PCB uses all thru-hole components for easy assembly (with the exception of the 4 inductors which are SMT), but some soldering skills are still required.

The project consists of a bare PCB, a parts "kit" available as a shared cart from Mouser electronics and the on-line documentation you see here.

The PCB is available from OshPark PCB fabricators at the following link: [url]https://www.oshpark.com/shared_projects/mYxj6roI[/URL]
The PCB is created in multiples of 3 for a cost of ~$54 or $18/board.

The parts kit can be ordered from Mouser Electronics: [url]http://www.mouser.com/tools/projectcartsharing.aspx[/URL]
Enter the Access ID code: 90C2DDF260. The parts kit to build 1 PCB costs $55.68.

The following documentation is available below to aid in construction of the project:

MA-3D Schematic.pdf
MA-3D Parts Locator.pdf
MA-3D Assembly Instructions.pdf
MA-3D BOM.pdf (Generic bill of materials with part references)
MA-3D.zip (Gerber X274 files if you want to use your own PCB fabricator)
MA-3D PCB.pdf (X-Ray view of the PCB w/traces, pads and silk screen)
MA-3D.png (X-Ray view of the PCB w/traces, pads and silk screen)

Well, that’s what they say. I’m about to try Asahi Linux (Fedora) on my Mac Mini with an M1 chip. There hasn’t been Linux for it for a long time, the M1 had to be reverse engineered, or at least ‘discovered’. Apple of course was no help. I hope this version helps with the sound from my Mac Mini. We’ll see. I think the Mini’s sound is pretty good if not a bit dry, depending on the DAC. I find direct from the SACD/CD player to be better though.

Fedora: ”With Fedora’s excellent 64-bit ARM support and mature development process, you can expect a solid and high-quality experience without any unwanted surprises. Fedora Asahi Remix is based on Fedora Linux 39, the latest Fedora Linux release with the newest software versions across the board. All M1 and M2 series MacBook, Mac Mini, Mac Studio, and iMac devices are supported.”

https://asahilinux.org/fedora/

About the audio: “Over the past two years, we’ve worked hard to pioneer the world’s first fully integrated DSP solution for the desktop Linux ecosystem. Just install Fedora Asahi Remix and enjoy high-quality audio right out of the box, no setup needed. We’ve worked together with the PipeWire and WirePlumber projects to add support for fully automatic and transparent DSP configuration, and then individually measured and calibrated 8+ different machine models, designing a customized DSP filter configuration for each one.

With our in-house Bankstown bass boost technology and our own pioneering open source Smart Amp implementation to safely provide full loudness and dynamic range, the result is the best audio you’ve ever heard on a Linux laptop. And we’ve even optimized the scheduling and power consumption of the DSP processing, so you’ll get excellent battery life while playing back audio.”

Hello all… beginning to enjoy this great hobby as I approach a more laid back lifestyle. The older gears from the 90s and 00s are my interests.

Hello everyone. Since I’m an old guy, I’m step-by-step refurbishing/fixing all my beloved SAE stuff: presently SAE 3200 tuner, second hand, US version 110V. Well, first step, since I live in
Europe, I successfully swapped the original 110V xformer with a 220V toroidal one. Then all the polarized caps. Push buttons have bad action and uncertain result. Is the tuning knob driving a variable capacitor or a resistor? I see three-legged capacitors (?) that could be filters… Sorry, when I’ve no schematics, I feel lost. Can anyone out there help the whole service manual or at least the schematics, please? Of course I’m willing to pay for it … thanks for a kind reply, if any. Cheers.

Selling a NP D1V33 including the case, only high-quality components were used, the clone DAC works, this was developed by Spencer using 4x PCM63PK, PMD100 to SM5842 converter. Spencer (FET Audio) did this D1 clone a while back. I can provide the Diagrams for the NP D1 DAC clone (enhancement)

I had this running for a few years. But I switched from the balanced signal chain to single ended and have no use for the DAC anymore. I can also add the CS8414 receiver and the SM5842APT that I used before the PMD100. The D1V33 DAC is delivered with the Aluminum Case from Schroff (hight:110mm, deep: 320mm, wide: 430mm Front:485mm) as shown in the pictures but without the two transformers.

If anyone needs pictures, I can send them by email.
Following two Transformers needed with min specs. 2 x 9V/30Va and 1 x 18V/30Va
The DAC is located in the EU, I would prefer to sell it within Europe, but other Countries is possible as well.
The price I’m asking is 400€ plus shipping with DHL and 5% PayPal fees.

Happy to be in the community.

I have made a mistake, I feed the Recitifing tube 6.3V instead of 5V for the glow. Of course did the tube end in an instant and painles death. It was more painful for me...
I rumbled around in my box with good tho have stuff and found an salvaged used 5Y3 and stuffed it to my SSE.
To my joy did the 5Y3 work. However are the voltage drop according to datasheets 60V and the GZ34 has only 10V.

What does a dropp of 50V or 20% of the B+ actually do?
I have not changed anything else, the anod resistor are the same. With the GZ34 was the cathod curret 56mA and dissipating power was about 20W. With lower B+ voltage do I assume that cathod current and dissapating power also will drop?

The 5Y3 has according to datasheet half the current capacity (125mA), as I'm in terory close to 125mA with 2x56mA do I assume it will not live for ever and eventually do I in the near future need to buy a GZ34 or do to solid state.

Looking for the schematic to trace a problem on the amp board and get the correct part, if needed. Thx.

Looking for D3a nos. Anyone willing to sell?

I picked up a Phase Linear 300 that needed repair. The overall build quality wasn't that great so I decided rather than repair the existing boards I'd design and build new ones. My first breadboard used bipolar outputs and I found that I had to run them with a fairly low bias current to keep the amplifier from overheating. Phase Linear amps always seemed like they used heat sinks that were marginal at best without fan cooling. I decided to go with lateral MOSFETs and run them at 50 mA bias current. With the stock transformer I get 130 watts RMS with both channels driven. The THD is less than 0.005% at 20 KHz, and improves at lower power and lower frequencies. So this circuit meets or exceeds the original. I've been using it for 3 months with no issues and I just laid out and ordered a second board with the provisions for boosted power supplies for the driver. That's the schematic I attached to this post.

Good afternoon all,

I have recently noticed the PCB in my ARC preamp has quite a bit of discoloration around a stack of 6 resistors near the 6550 tube. A quick Google search revealed ARC must have reworked that part and used a single high power resistor later on.

Does anyone know the value of the parts there? The resistors look like 6x 1.5k in parallel giving 250 ohm but what about the carbon resistor next to them? I've tried to find pictures of other REF5's but none are clear enough to read the value of the carbon one and the single power resistor they used later.

Sony TA F444ESX
I have here for sale this amplifier in perfect working condition and in great visual aspect.
Everything is working just fine,sides constructed in solid walnut with the original screw
covers, seeing by having more equipment of the genus.
For buying or bid please check here or get in touch:
https://www.ebay.de/itm/326310639782

I installed my own protection circuit into a Bose 1801 power amp. After I used the amp for a week or two, the transformer I installed to power the relay started buzzing loudly.
It is a loose mechanical sounding buzz that changes or goes away when I rotate it, press on it, or tap on it.

I don't think I overloaded it but want to check with people here to make sure I didn't do something wrong before I chalk this up to random failure and reinstall a new transformer of the same part #.

The transformer is a 186B36 and it powers a big LY4F-DC48V relay. Transformer is rated for 6.12 VA/170mA and the relay coil current is 30mA. That seems like plenty of headroom. But I don't want this amp to come back with the same issue, so here I am.

I’m trying to fix a home theater receiver for a neighbor. I don’t know how it happened exactly, I don’t even know how it could happen, but his son was unplugging it, and somehow shorted the hot and neutral line together on the power cord. There was a pop and now there is no action at all from the receiver. No standbys no lights, completely dead.

I have looked and looked and cannot find a service manual or a schematic, so I’m going through and seeing if I can find any bad components. I checked all the obvious like fuses and such but I am working on this standby power supply board.




All the diodes and transistors seem to be working, but I am onto testing this optocoupler. From what I understand, you can put a little bit of voltage across the internal LED and measure resistance on the other side. Using a Peak Atlas DCA75, the led side measured good with a forward voltage of about 1.15v. The other side had a forward voltage of a little over 10 volts.


I’m injection voltage to the led, + to anode and - to cathode. I’ve had resistance go down to 49 ohms, but then I’m hitting current limiting on my power supply.



I at first set the limit of current to 100 mA, but hit that limit quickly. So I raised it to 200 mA, but hit that with only 1.77 v going to the led. That seems like a lot of current draw for a led. I didn’t take it any higher for fear of damage and it was indeed getting warm.


I tried a limiting resistor of 2k (not having a schematic sucks by the way) but no luck. After the testing I measured the led side with the peak again and it still measures exactly the same.

Does the optocoupler seem to be behaving oddly? Is there a better way to test it?

Thank you,
Dan

Hi all! A complete noob to loudspeaker design here. I have designed amplifiers and home automation circuits in the past but Loudspeaker and crossover design is a completely new thing to me! Hoping to get educated inputs from veterans in this field.

I have a few different types of transistors I am hoping to use in Fuzz pedal builds amongst other projects, mainly PNP germanium.
What are the desired ones to be used? I know NKT275's are very sought after alongside a few others.

Also I am interested in certain famous pedals used certain transistors, some of which I know little about. What famous or great sounding pedals used what transistors exactly?

Also does anyone know what the 'P' designation means on NKT transistors? I have seen a few with NKT275P stamped on them, do they differ from the NKT275 at all? I have a couple of them with the NKT275P designation, I think they are quite low the hFe on them, like in the 30-40 range.

I am finishing a 4 channel tube microphone preamp build. The audio channels are based on EF86 and ECC88 tubes, and there is a solid state power supply with a regulator for high voltage and one for filaments.

If one of the input transformers is left without input load termination, there is noise on all the preamp channels.

With no load resistor across the input transformer secondary, noise is 2Khz and upper harmonics. With a 130K load resistor, noise is 20KHz.

How should I properly deal with this situation ? Obviously it's not acceptable to have all the 4 microphone input plugged in at all time in order to maintain noise free operation.

Do I have to fine tune the secondary load resistor, or perhaps adding a zobel network ?

I present this circuit for general discussion, it is based on the ETI project 470 from November 1979. My scaling to 20 watts (into 8 ohms) works and has worked flawlessly for several years.


Fire away!

I have a Pioneer SX-950 that recently cooked resistor R38 (150 ohm) and the 4 outputs as the result of VR4 (100 ohm) trim pot shorting out. All trim pots were replaced with new Bourns pots, R38/R40 replaced with new 2w resistors and new outputs on right side as well (MJ21193/94). Unfortunately now for some reason the Bias on the right channel (facing front of unit) will not trim below 27mv , while correct spec is 20 mv. The only I can even get it to go to 27 mv is with the trimmer turned all the way to the right. Any turning to the left brings bias up to very high levels (200-250mv). Left channel is fine and to spec. I am running it with a DBT to bring some level of protection to outputs. When turned on I get a protection click after 5-6 seconds and DBT says no shorts or opens (bright then dim to nothing). Please note that was running fine and to spec until the R38 went open. Have checked the components in the path of VR4 and can find any open or short items. Any suggestions where to check or look. Assistance would be greatly appreciated.

Hi guys I'm consolidating my projects so I'm selling of a pair of Faital HF140 drivers with matching LTH142 horns on very good condition used in a home system only. Faital rates these combo at 65 watts at 600hz, low power SET fans could run them lower with the right crossover. Mortite was added to the horn to improve damping. They come with original boxes and will be double boxed. Super smooth response and low distortion. $500.00 a pair plus shipping in CONUS only.

SOLD and shipped.

In light of the JJ 2A3-40 plate dissipation of 40 compared to 2A3 which I think is around 15. How should I adapt traditional 2A3 schematics to get this extra wattage? Would anyone have an example of SE schematics specifically adapted for this tube, voltage/current? I'm coming up empty for proven schematics but if it's just as simple as getting the tube to run at a different voltage operating point, what would that be?

Newly acquired a (variable speeds) Goldring 88. It needed a new idler tyre plus general lube and fettle. It's run for a few hours now so thought abt a re-check of the speed using the accompanying Goldring strobe disc and an LED table lamp.

Then I remembered Gridwatch. A single page giving real-time power grid data including exact mains frequency for nerds like me. True, engineers try to keep the total number of cycles per day accurate but the frequency throughout does vary fractionally. The needle on the dial showed more deflection than I'm used to though I've seen it more off than that. The frequency was 49.85 Hz. If you translate that to concert pitch 440Hz that would play at 438.7Hz. I reckon a guitar tuner would pick that up but I wouldn't. Point is, if I see the strobe lines move, whatever the mains is doing its caused by the deck!

If you are setting the speed using a strobe you're locking it to the mains frequency at that time. Best to glance at what you're locking it to, or possibly just get a life....

Hi to All and good morning
If I understand well a good home theater system should provide high SPLs with very low distortion
The natural answer to me should be a pa system
Anyone doing this?
Moreover if you happen to play classical music on it are you pleased enough?
Thanks a lot for any kind and welcomed advice
Kind regards Gino

As per the title, "unopened" spool, 32 EUR + shipping, EU only, PayPal F&F (or G&S + fees). Thanks for looking!

Edit: Registered shipping within the EU would be ~10 EUR.

Looking for experience with the remote volume control kits sold using Alps pots.
Are they real or fake Alps pots and how have they performed for you?

hello
I received this prestigious amplifier from a Japanese auction.
technics A99 or SU-8099
it is still nicely preserved.
but it has a problem... It turns on but there is no sound...
no click of the relay can be heard... ? what to do
the fuses are all ok
I am attaching pictures.. it was very very very dusty. He had 5 kg of powder. crazy
after cleaning it looks like this.

Here's my intro...
New here obviously. Long time audio tinkerer, literally since I was a 5-6 year old child. I started off taking my parents clock radio apart, and managed to put it back together well enough they didn't notice. I was hooked after that and summarily started taking apart everything. Record players, alarm clocks, the dryer. (Got lucky on that one and woke up in the opposite corner in the laundry room) I'm still at it, 50+ years later. Been soldering since I was around 6, and failed to mention that in every field related job interview since. Went on to recording studio engineering (when they had parking lots, not driveways) live touring, corporate audio and video engineering. (I only did that briefly. Corporate will steal your soul) audio trucks and TV trucks, doing live sports, entertainment, and live multitrack recording in said trucks. Still hide the fact that I can solder, unless it's an emergency. Regardless, hello to everyone.

Hi, I’m working on a Digital Design car amp for a friend and I need help getting the same part. It’s a B20k potentiometer it has 6 pins, it’s blue plastic and has a black plastic screw head for adjustment. Reason for replacing is the screw head is stripped. Thanks In advance.

help me!
in the past ive made some butt ugly bluetooth and passive speakers and want to take the plunge with making something a bit more classy.
i currently have a pair of ma chn110 drivers that have been sat under my work desk for 6 months whilst i decide on a cabinet for them.

final cabs cant be too big, the wife is short!!

my current short list

pensil a11
pensil 103


oryxchr120
and the kewel compact

both pensils are about the limit depth wise and the oryx and kewel i could do if i put the port on the front rather than the back.

any downsides to squeezing the chn110 into any of the above ?

any advice appreciated

cheers

steve

SOLD

For more info see the build thread here https://www.diyaudio.com/community/...l-ht-system-w-linaeum-focal-and-morel.415843/

Drivers, crossovers (XO’s), and partially completed enclosures for qty 6 speaker systems using the included cabinets; up to 24 monopole speakers systems with additional XO’s.

Higher resolution photos: https://photos.app.goo.gl/UhQvTqLrBa18QMjFA

24 ea modified Focal 4C212 bass/mid drivers 50 lb (cost $685)

22 ea RS ET-5A (unused) and qty 7 ET-5 (used) Linnaeum monopole tweeters 16 lb (cost $580)

4 ea XO’s for 4C212 and ET5/A 7 lb (cost $160)

2 ea Morel MW168 bass/mids 6 lb (cost $280)

2 ea XO’s for MW168 and ET5/5A 4 lb (cost $80)

4 ea Side surround enclosure 10 lb ea free + shipping

2 ea back surround enclosure 12 lb ea free + shipping

2 ea partial subwoofer enclosure 20 lb ea free + shipping

8 ea 2” dia. X 7” L Precision Port tubes and 6 ea couplings 27 oz total free + shipping

5 ea Optimus PRO X77cast aluminum enclosures 5 lb ea free + shipping

Incomplete subwoofer enclosures (one is damaged) free + shipping

Box of capacitors, inductors, resistors, and misc parts 5 lb free + shipping

Polyester from a couple of pillows for box stuffing free + shipping

Packaging materials will add to weight & shipping cost

Total cost was $1785; asking $450 + shipping

$75 off for local pickup in Mountain View, CA 94043 (saves me a day of packing)

All offers considered


Drivers, crossovers (XO’s), and partially completed enclosures for qty 6 speaker systems using the included cabinets; up to 24 monopole speakers systems with additional XO’s.

Higher resolution photos: https://photos.app.goo.gl/UhQvTqLrBa18QMjFA

24 ea modified Focal 4C212 bass/mid drivers 50 lb (cost $685)

22 ea RS ET-5A (unused) and qty 7 ET-5 (used) Linnaeum monopole tweeters 16 lb (cost $580)

4 ea XO’s for 4C212 and ET5/A 7 lb (cost $160)

2 ea Morel MW168 bass/mids 6 lb (cost $280)

2 ea XO’s for MW168 and ET5/5A 4 lb (cost $80)

4 ea Side surround enclosure 10 lb ea free + shipping

2 ea back surround enclosure 12 lb ea free + shipping

2 ea partial subwoofer enclosure 20 lb ea free + shipping

8 ea 2” dia. X 7” L Precision Port tubes and 6 ea couplings 27 oz total free + shipping

5 ea Optimus PRO X77cast aluminum enclosures 5 lb ea free + shipping

Incomplete subwoofer enclosures (one is damaged) free + shipping

Box of capacitors, inductors, resistors, and misc parts 5 lb free + shipping

Polyester from a couple of pillows for box stuffing free + shipping

Packaging materials will add to weight & shipping cost

Total cost was $1785; asking $450 + shipping

$75 off for local pickup in Mountain View, CA 94043 (saves me a day of packing)

All offers considered