Hello everyone,

I have finished my second ACA and this one has 2 problems. First one works great.
1) big thud in right channel on power up and. Both channels after thud emit the usual whining sound.
2) left channel goes silent after 5 minutes or so.

I checked all connections/soldering/continuity etc.

The amp runs slightly warm not hot like normally does.

Could it be the voltage is too high, spike (I use a voltage reg) although I took good care to keep it at or very near 12v

Any other suggestions?

Thanks

Hi. does anyone know if the are any difference between the top and bottom transistors? one does have an X in front? Thanks.

For sale a working Hypnotized AD797 MC Phono stage. Complete with R-core transformer, metal cases and accessories to build nice set.
I have no time to ever finish this project. Asking price is 200 euro. From the Netherlands, can ship worldwide.

Hi All.
Sorry for my absence from the forum.
Had been caring for my mother, who recently passed away.

I was hoping for information & assistance with a pair of Mordaunt Short Pageant Series 2 Loudspeakers.
The owner finds that they no longer sparkle for her.
I played a familiar track on them and found they're a little dull sounding and lack sharpness across the range.
The 2 toggle switches on the rear are a little strange.
Both are set in the up position, but will not switch downwards.
I've put some force on them but they won't budge.
I was concerned not to put too much more force on them for fear of damage.

1. Are the toggles switchable up & down and which direction is flat & which is bright?
2. Do these toggles switch the path between direct & through the resistors?
3. Is it desirable to avoid the signal going through resistors, especially cheap ones?
4. If I leave them switched bypassing the resistors, then is it pointless replacing the resistors?
5. Is it worth replacing the electrolytic caps to poly or should I just get fresh reasonable electrolytic replacements?

I plan to remove and measure current caps, but thought I'd post first.
There is currently a single 10mfd & 2 x 5mfd's fitted to the x over.
thanks cliff

Hi all,

thanks for all the assistance as always and apologies in advance if this is a silly/basic question.

I’m hoping for some assistance in matching two drivers of different impedance, a JBL 2446h (8ohm) and 2447j (16ohm). I had initially thought I could run these off two different channels of an amp as I understand that the two channels can work as separate amplifiers but is this a valid approach?
If so I guess I could use an xlr splitter cable from my x-over to achieve this but does anyone foresee any issues with proceeding like this?
Im struggling to find a matching 2446 or even similar 2” driver at 8ohm which is why I’ve been pushed to use this approach (my horns are designed for the 2446 so will be making my own adapter for the 2447).

If anyone has any suggestions / alternative options that I could explore I’m all ears!

Thanks,
Lawrence

At the BAF2013 Mr. Pass presented a nice JFET preamp. Today I cobbled up a quick prototype of one channel to test its behaviour and it's very nice. I have a BL rated Toshiba JFETs so some values had to be changed and some parts added (P1 to set the DC offset at the output and harmonic content, caps in cascode voltage divider to improve HF extension a bit). Serious build with buffer added at the output will follow. For the time being here is the schematic and the PCB layout of the preamp (copper side view, 45x50mm) :

EDIT (Oct. 27, 2013): 'final' schematics and pic of built preamp are in the post #66

All channels are sold.

Hello. I have this amp from years ago and it has always worked fine but a few days ago the left channel did not work and it damaged my column. I could smell burning. I have opened it and it has two blown fuses on the amp board.
I have checked the two transistors and they are shorted but it does not let me see which transistor it is. It has the identification erased. That is why I need the service manual to identify those components
If someone can pass it to me, I appreciate it. Thanks and regards

Hello,
i need a schematic for DC protection on a headphone amp. Let it be with transistors, THT.
Have you experienced such a scheme?
Thx.

Hello everyone,

I'm working on a project that's based around the idea of "digitally controlled analog". This project should include some basic EQ functionality to show the usefulness of other parts of the device.

Theoretically, a Baxandall style circuit should be perfect, so I went with the "Active / Single Bass Capacitor" variant from https://www.guitarscience.net/tsc/baxandall_2.htm#

My first idea of implementing digital control capabilities were digital potentiometers, which lead me to the same problem with massively distorted audio as described in this post from 2004: https://www.diyaudio.com/community/threads/digitally-controlled-baxandall.28022/
Given the age of that post, I'm curious whether nothing has changed over the last 20 years - at least I was using modern digipots that were designed for higher analog voltage levels: https://www.microchip.com/en-us/product/mcp41hv51
(The pots were powered with +/-15V and the voltage across them was never near their maximum.)

My next best idea would be motorized potentiometers, but I'm not sure whether dealing with motor control circuitry is worth it, considering their performance.

Since the values need to change in real time, preconfigured values that are switched by relays aren't really an option either - the zipper noise of digipots would already be prolematic.

The eq feature is too important for the project to be left out, but not important enough to go down another rabbit hole like vactrols...

Has anyone got another idea? Maybe in the form of a different digipot, a different eq circuit or a different way of adding digital control to existing circuitry. 🤔

Thank you all very much in advance!

SOLD AS IS
I know nothing about them.
Please see pics.
$180 shipped USA

As the title states, I'm trying to understand more about the possibilities of swapping out compression driver diaphragms with different diaphragms. On another thread I was told that it can be done, and possibly some CDs have multiple diaphragms that can be used? But I'm finding zero information online. And I thought I should make a separate thread for this question.

The reason this question comes up is because I'm using coaxial drivers (B&C 12FHX76). This coaxial design shares the magnet, so I can't swap out the entire compression driver. But what if I can find other diaphragms that would work? Could I improve the unfiltered response of the CD?

I am a noob as far as compression drivers, so I don't know how much impact the diaphragm has on the CD's performance vs how much of an effect the internal structure has. I suppose it is entirely passible that changing the diaphragm will not have much of an effect, but I want to ask. If I had parts laying around I'd swap them and see. But unfortunately I don't have any parts to play around with.

If we find that the diaphragm makes a difference, what is the chance that a diaphragm from one manufacturer will fit and function well in a different manufacturer's CD? I don't know if the curvature of the diaphragms is going to be the same, and it seems to me that the internal clearances are important. But at the same time, I suspect that physics involved forces the internals to be pretty similar?

I've seen some designs using polymer diaphragms that seem to perform quite well. And then there is the Eminence carbon fiber diaphragm. It'd be sweet if I could mix and match to fine tune my driver's performance. But will it work?

So I am working on something that can be used for Ivey's 2N2222S phonostage, the opamp Hagerman Bugle phonostage and Pass Labs B1 with Korg triode tube preamp.

I built Elliot Sound Products cap multiplier out of spare parts for a 24V output and have a few questions if anyone has any comments or opinions.

I attach a schematic.

And here are my questions:

1. I don't understand how the voltage output is adjusted. Can anyone give me a hint? I'm useless with transistors.
2. What I end up with rectified voltage is always a mystery to me. The overspec'd transformer and bridge gives me 28.8Vdc. Where I guess I would have expected 31.2V [(23VAC x 1.41) -1.2]. Oh well I was hoping for 27V rectified volts
3. Am I on the right track for a good power supply for a phonostage or preamp?

Thanks much,
Dan

Hi all,

I got a BeePre gen 1 in for repair. It has the upgraded switched attenuator with two switches, one for coarse and one for fine control. The schematic I have does not include the upgrade. On the attached image, the two resistors noted by red arrows, are burned black and I'm unable to read the value. One measures 820 ohms and the other is 940 ohms. From what I can by blowing up the pic, they appear to be 1K parts. Can anybody confirm that for me please?

Part 2: What could possibly cause a resistor in a volume control to get that hot?

Customer says the unit ran hot, maybe the regulators boards?

I'm not familiar with this unit, so I don't want to just plug it in. It has some age on it, so I'm going to replace all of the electrolytic caps.

BTW, the contacts on the switches on the actual unit (not in the pic) were black and when I sprayed some contract cleaner on them, the stuff liquified and was a tar-like material. I removed as much as I could, but I could only get the wipers clean.

Any advice will be appreciated.

I have a couple of these trialed then put aside, long ago. So long, when I tried to take pics, my finger went through the hardened foam. I found foams that should fit, but are not original, and may themselves of got lost now. Miss-shaped is more likely, as they were in a document envelope.
I really need to find these a home. They still demand $200 each, new. These are almost certainly the originals, not the later factory. I'm not going to price them though. I want to see them used, but they need a massive box, or an OB project. After fixing them.
Anyone who's gives time to the forum, can have them.

I think the foams were actually listed as infinity, and likely a search result here.

A friend of me is looking for a service manual for DAC and power supply units (Einstein made) so as the KSS-240A (and in some devices of this model KSS-213B) mechanism (SONY made).
The last wanted must actually be easy to find as long as one know, in which HiFi system or single cd player model from SONY is the same mechanism.
Thank you very much for an advice.

Hi,

Anybody out there with the service manual for the CD player
Musical Fidelity Elektra E601
(I assume that E60 will do as well)

My CD player refused to start up yesterday. There is some noise as if something in the transport spins up, the display comes alive for 0.5-1sec or so then it goes off again and the cycle repeats.
Today I left it flashing on and off for some time and then it came alive. It plays discs and all seems to be fine.

All this happened when I opened it to inspect. Now it is hard to fix if it is not broken. Still I am pretty sure the issue will come back.

I have contacted MF some time ago about the schematics/service manual but they refused to send anything...

So if anybody has anything could you please send it to me?

Who can upload the schematic diagram ?

I have the Harman Kardon. 775. Mono blocks. The problem that I'm having is turn on on one amp gives initial little buzz sound and goes away. The amp works perfectly after that. until the next startup. Does anyone have an idea? What is the problem? I adjusted the DC offset to zero. And the idle current to 36 millivolts.

.

1. I need to drive 2 x 4 Oms per channel (bi-amp per channel). I have ~800W toroid with quad output / +-65V x two linear power supplies. Would these PSUs be sufficient? Is there anything special I need to implement to decouple amp modules from each other 🤔?

2. Re: Input Voltage Driver Referenced to V-
Just to double check the connection: +Voltage Driver source must be connected to amp module; - Voltage Driver should be connected to V- (-65V); am I right?

Thanks a lot in advance!

Hi all,

First, a confession - I've killed my O2 headamp after many years of excellent service. Very stupidly I plugged the wrong power jack in and rather than receiving 15V ac it got 21V dc off an SMPS. The power led still lights but no sound out, I haven't opened it up yet to see what's fried...

So, two questions that I'd appreciate some adivce on:

1) What am I likely to have killed in the O2 and given it's age, is it worth reviving?

2) If the O2 is not state of the art these days, recommendations for a new headamp. My headphones are HiFiMan Sundara, 32 ohm IEMs so fairly current hungry. I don't need the amp to be portable and don't need an integrated DAC. I prefer revealing, uncoloured very low distortion amps, is there anything out there taking advantage of the newer OPA 16xx series? Valve amps need not apply, just my preference. 🙂

Thanks in advance for all contributions

Pair of Toroidy TTG-EL84PP with rubber pads and stainless bolts/washers

8K - 200mA - 4/8 ohm 50W UL

https://sklep.toroidy.pl/en_US/p/TT...sformer-8kOhm-2xEL84-Push-pull-or-similar/561

£110 plus delivery. UK only sale

Sold

Already have done two project with Satori 6 inch and 5.25 MAOP10. Planning to try something new with 6 inch driver.
Please suggest some good driver which can be on same level or above Satori or MAOP10.
Thinking about Fostex https://www.fostex.jp/wp/wp-content/uploads/2014/08/fe168ez.pdf

Well a while ago I did an intro thread kind of told everyone what I got and what I was planning and mentioned my dad and Daniel who are both on the board.

Last year my dad convinced me to get the KEF 107/2 (came with the proper kube too). He also found the exact same Krell KST-100 he once had (which I vividly remember from my childhood).

I am hitting 40 soon while my dad has been at this for 40 years; designing and modifying his own audio equipment, all of which I vividly remember since I was 5.

So after purchasing both, he recapped the KEF 107/2 for me (except the hard to find 240uf caps but they were fine), reformed them, redid the woofer cones and refilled the ferrofluid.

I finally brought them into my home in the new year and started listening to them

1. Minipc for the source (Tidal)
2. Portable phone DAC (cheap $100 USB powered from amazon)
3. Some cheap bias knob pass through for volume control ($30-$40 on amazon), 4.4mm balanced <> RCA connecting to the DAC and RCA to the amp

The sound was muddy, not enough bass, not clear, I used FX Sound (free windows EQ software), it helped, but it was still 'not right'.

I spent hours playing with speaker position and tweeter direction. In the end the best sound in my space was bringing them as close as possible (KEF recommends 2.4m, mine are wider), over 1/2 meter away from wall and titled/toed in entirely, with tweeters directed towards me so I get a triangle seating position. This was the best I could pull off.

No amount of EQing could get the soundstage or sound to improve further from this, so I kept researching DACs for months, all pricey or bad reviews. Long story short, I got sold on the SMSL SU-1 as an entry united but it was going to take a month to come, SMSL C-100 was here next day (I went through a lot of youtube reviews). Yes I am aware of R2R DACS, even the Gustarted R26, SMSL's R2R DAC, so many other 2k+ options. Even mid-range SU-10, SU-9 Ultra, D400EX, so many options but I ended up going with this, cheap and next day shipping.

Boy... did it wake up the setup, the portable DAC was GARBAGE (obviously), no need for EQ adjustments. It also had 6 filters, kinda useless, except 2nd option was 'warm' and I liked that. Boy big change, but still not 'right'.

Next, I figured, let me get better cables. What I had in place was plain copper wires, chopped at both ends and 'tugged in', with the biwire option also 'tugged htrough' with the plastic sleeves chopped so it passes through the posts.

First thing I got was new cables, banana to spade. Boy it made a difference, I listened to two days and it was nice once broken in, an improvement in sound stage. Right away next I ordered spade to banana bi-wire jumper cables, once again an improvement compared to the chopped copper cables that I used as jumpers.

Then I ordered some RCA cables and connected the Kube, boy, do NOT listen without a Kube, the sound was smoother and more controlled. I played around with the LF and HF knobs and I could hear a difference, initially I increased the LF to the max for impact, but it dulled and caused bass to be boomy.

It still didn't sound 'right'... so I kept reading and realized wait, I have 4 posts on my Krell, so I looked around for better cables and got Full copper oxygen free cables with gold plated bananas on both ends. Connected to the MF/HF posts straight from the amp, it sounded 'warmer and smoother'. Then I did the same with the bass and it sounded 'dull'.

So I was confused, but then I read reviews on these cables (Micca on amazon) and everyone raved about them, so I figured, I am too hasty, give them time to break in, so I listend to the 2.5 days straight and they improved but something was still 'off'.

Tonight my parents came over and while listening he told me to turn down the LF on the kube and set it to the neutral base position, I did and while the image was cleaner it didn't have the impact or oomph and I hated that. It all still sounded dull.

Well yesterday I ordered legs for the speaker spikes to sit into (they come with spikes which a lot of people don't know, the bottom plastics come off). Well I got the nickel plated ones (cheap order from amazon) and installed it with my dad.

HOLY crap, who would think LEGS make this much a difference. Instantly EVERYTHING sounded better I **** you not. Bass was clean, impactful, not boomy. So much details started showing up in the sound image, airy details of instruments, voices, strings, INCREDIBLE.

Since they left, I've been relistening some of my testing music and I am so impressed. They sound PROPER now...

So when people say small details are placebo, no they are not, cables, position of speakers, these spikes preventing resonance and boominess, better control, it all came together.

One last thing is arriving tomorrow, ordered CARDAS XLR jumpers for grounding (as they didn't come with the sale of the KRELL amp). I hear light noise on the right speaker tweeter, my dad told me to get this, so that's next.


That's my update, I love the setup, it is so harmonious, clean, smooth, warm, clear, detailed and impactful, you can hear the air moving, the depth of the stage, which was all missing when a bad dac was in place, bad cables and no proper feet on the KEFs (the plastic was driving everything into the floor).

Anyways for the future plans a better DAC, monoblock aleph amps and perhaps custom enclosures like what my dad once built are all down the line, but tonight everything came so nicely into place. I am blown away how the removal of the plastic bottoms altered the quality of the sound so much. I got goosebumps, it was so satisfying.

I want to build an H-Frame enclosure using a Dayton Ultimax UM18-22 driver. Specs HERE.

The baffle would be 20x20 and I am wondering what size for the depth.

Hello,

I thought it would be an interesting project to see if I could make a smaller subwoofer to move to the patio for a little extra bass in the summer.

Criteria
1. Portable - keep the size and weight down. 1.0 to 1.25 cuft
2. Not looking for low bass, but rather a punchy midbass to fill where the outdoor speakers leave off.
3. Efficient'ish -- I have a 500watt sub app for the project to reuse.
4. 10" or 12" drive max
5. I am using a WiiM Pro as the source and it has a parametric EQ so I have decent control for some fine tuning.

First driver that caught my eye was the Dayton Audio - RSS3315HO-4 (not the -44). I fired up WinISD and with a 30 Hz tuning things looks ok. For comparison sake, I thought I would try a couple other drivers. The UM12-22 (thinking it should not be ideal in a small vented box) and the MX12-22 (also likely not idea). As I thought, the MX needed a larger enclosure so I rejected that option. Here is the strange part, the UM12-22 seemed to model better in every way than the RSS315HO-4. What really didn't make sense to me was the output (set at 300W in WinISD) was that the UM12-22 had more output but is significantly less efficient?!?!?! I double checked the T/S parameters in WinISD -- looked ok. The other thing that didn't make sense is that the vent length was identical for both (1"x12" slot 25.77" long). That's a long vent but I think I can make it work.

Questions
1. Did I make a mistake some place and my model is wrong?
2. Any other reasonably priced drivers I should consider? SB Audio ones seemed to require larger boxes

Thoughts or comments welcome

Cheers!

Hi all, my amps not clicking on. When I disconnect the power rail the relays click on, but they don’t when connected. DC is fine.

Hoping someone has a service manual? Maybe even help me diagnose the problem.

Thanks gang 🙂

Hi guys,

does anyone know if there is a service manual available somewhere for the Myryad MA500?
I want to recap mine (23+ years old and it runs a bit warm). During dismantling I discovered that no bleed resistors are built in: the psu pcb shifted a bit and the filter caps discharged unplanned and uncontrolled on it's own mounting bracket. Optically, there's no damage other than a black spot on the pcb. But I can't test the unit at the moment. During the recap, I might as well replace any and all components around the fried spot on the pcb. Including some diodes I know nothing about, except a voltage rating of 22V (D609, D610). So a service manual might come in handy to identify risk-areas and components.

Thanks in advance!

James.

HELP WITH HICKOK 539C!
Hello everyone, I am writing with the hope that someone with more experience in the repair and calibration of this equipment can help me, I am calibrating the Hickok 539C and so far everything is going well except that when I set the function switch to H the fuse lights up brightly. , I only found this when it is set to H, I don't know if this is normal or there is some problem (short) in this switch, any help will be greatly appreciated.
greetings
Alex

The interface is basically brand new with all protective films still on. Bought it for measurements, but never got into it. Plugged it in only to check if everything works ok. Price is $95 + PP fees + shipping. US shipping only. Thanks!

Selling 2 new genuine Pioneer PA0016 chips still in their original bags(never used) purchased years ago from Pioneer distributor .
I had a Pioneer A-717 amplifier that i never repaired .

These can be very useful for someone repairing Pioneer 7-series amplifiers as these chips are obsolete and really hard to find .
Asking 50€ for both + shipping.

Thanks

SEAS KingRO4Y Mk III Active Loudspeaker Kit - as an OB?

Hi,
I was looking at the Madisound kits and was curious if you could do the KingRO4y as an Open Baffle speaker.

I seem to recall reading somewhere that for an OB, you want drivers with a QTS greater than .6?
Thought I could do one w the plate amp in the base?

With the 10" driver ... how wide would the baffle have to be?

This was just a thought that crossed my mind. More of a thought exercise than actual project.

Thx

Hi!

I found this tutorial on how to use REW and RePhase to do both EQ and Phase correction
Login to view embedded media
Hands down the most interesting and new way I have ever seen so far. Maybe not for beginners... but if you follow the steps maybe you can make it too.
I will try...

I have a tube preamplifier for my turntable that has no markings so I don't know anything. I also am extremely new to the use of tubes but want to upgrade the tubes in the preamp to potentially get a fuller and cleaner sound. The preamp has 2 of 819 6Z4 tubes. 4 of 6N2-J tubes and 2 of 12AX78 tubes. They all appear to be Chinese made and the preamp has a tag that is in either Japanese or Chinese. Can anyone help me find upgraded tubes?

Damaged mine and hope to find replacement. Please let me know if you have one for sale. Tks. Richard

I'd like to get hold of a pair of the old Seas M15CH001 mid drivers. The ones with poly cones and a copper phase plug. PM me if you can help, thanks.

Here i have for sale NOS KSC2690A-Y+KSA1220A-Y 4 pairs (total 8devices + 2xKSA1220A-Y). This is high gain BJT using Y markings and used in VAS stage of audio amplifier or output stage in preamplifier. Manufacturer is FAIRCHILD and is new newer used.

Price is €20,00 (for 10devices) + Shipping + PayPal fee.

Any idea what output transistors the Parasound A21+ uses?

They appear to be MT-200 case and perhaps 2SC2922 and 2SA1216, but where would they be getting them, or do they just have a huge stash of them?

I'd be grateful if anyone has a schematic for the minimax preamp.

Thanks David

Hi All,

I have a pair of Zu audio Tone bookshelf speakers (I believe there were also called Omen bookshelf) and I would like to build a little larger cabinets to "squeeze" lower bass from them.
On the back panel there is "2010" so I believe it's the speakers production year, as far as I know there were few revisions for these speakers and there was a change in the full range driver at some point, from Zu260FRD/G4 to Zu260FRD/ND.
There was also a change in the super tweeter and in my speakers it looks like the newer model.
Does anyone knows which full range element has been used at 2010? And were I can find the driver's thiell small parameters?

Thanks

Dear knowledgeable folks of DiyAudio, I want to build a Goldmund clone amp, and come across these following boards. Which would you choose and why? Does anybody know on what Goldmund amps these boards are based? Any experiences with these boards and tips on the build are very welcome too.
Extra boards and extra info will be added in follow up posts.

Board 1: 200W Mono Power Amp Board based on Goldmund Line + PSU Board L11-30, 2SC2922/A1216

As far as I can tell this mono channel board comes with a powersupply board with speaker protection and rectification and 4x 10.000uF 63v Rubicon capacitors. The voltage rating on the caps seems too low to me to make this into a powerfull 200watt amp (I think it needs like 70v DC to be a 200watt amp, please correct me when I am wrong).

Any experiences or thoughts about this board and the psu board?

I recently got this 500w rms kenwood sub.
Can the amp twister f4 560 power the sub and 2 speakers by bridging maybe,if so how?

Hello,
A new fast fun inexpensive OB project. It is my second attempt to do a FAST OB. Several reasons to this defect but not suitable drivers.

Looking for a woofer usable for OB, I found this one, a driver for bass guitar : Lavoce LBASS15-15-8
Some challengers were simulated Fs < 40Hz Qt > 0.6 Not a lot of contenders.

• SB Audience 15OB350 design for open baffle, has the best max output level. My second choice because the Lavoce has a lighter cone and less expensive, less crossover cost.
• Celestion Pulse XL 15 Interesting but too much crossover work to have the same bass extension as the others.
• Eminence Alpha 15 Best bass response 40Hz less sensitivity 85dB and a peak in the group delay. The most expensive in the group 200€ ! Harder to find in Europe

The choice for the mid-tweeter : I saw a lot of tests and based on return of experience on the web : Markaudio seems to be the way to go. There are also Fostex FF85WK.
I want a good treble as good as dome tweeters. Many fullrange i listened to has not the treble I want it very realistic. And the mid is couloured... It is my opinion 😉.
For the mid_tweeter I tried first an Alpair 7ms, good mid but treble miss extension to my ears. Go to Alpair 5.3 the sound became ok to my ears.
I tried first a 6dB crossover, LR2 slope but the sound was sometimes muddy in the midrange. Go to LR4 slope, all things are OK.
I wanted to test the MAOP 5, my opinion it is a more refined and neutral driver than Alpair 5.3 . The two drivers have the same response on the baffle.
This design should work with FF85WK or Alpair 7ms, not tested with a LR4. The crossover is a little different, 8 ohms drivers.
It is not a very expensive speaker 500-600€/$ for a very good sound.

The bandwidth is 50Hz-20kHz 87db/2,83V . The Qt of the woofer on the panel is 0.8 and 36Hz resonance. I made some measurements, the response curve of the speaker is honest. The crossover frequency is 640Hz.
I was a little lazy for the construction, the panel is a shelf board with standard dimension 80cmx40cm.
It is a compact open baffle. I add a shelf bracket in the back to tilt the panel.

There are some similar old projects :
John Busch (RIP) Fast, fun, Inexpensive OB project
Martin J. King MV Model 3P OB Loudspeaker Project

I enjoy a lot the speaker, it works good to my ears.

Have fun.

Hi all, does anyone recognise these old Wharfedale woofer drivers. They are said to be 8 inch. I don't know what model they are from. Keen to know specs and any other info. Glenn

Please, let me know which is the highest transconductance cheap and easily available for RF and oscillator JFET & MOSFET N chanel you know? Preferably in TO92 or SOT23 packages. No more than 12V power supply needed.

Many thanks.
Kind regards.

This design is for use by folks who want to utilize the Anderson Powerwerx connectors that seat together for use in the standard back plate AC pocket. There are two options available:
Option 1) 8x Powerwerx Connectors.
Option 2) 4x Powerwerx Connectors.

After assembling the Powerwerx connectors together in a "plug" arrangement, the whole assemble firmly "snaps" into place into this 3D printed part, which in turn bolts into the standard AC mains input pocket that is already machined into standard Modushop Chassis. The fit is "friction fit" and is so tight that once secured in place, no additional tooling is required to secure it. If removal is necessary for whatever reason, a swift "hit" from a hammer on the assemble will dislodge it from the "snap in latch" design. Otherwise, it remains secure for use. If you want to add an additional mechanism to keep it secure, a M2.5mm x 40mm bolt through the assemble and printed part will ensure it cannot be removed (totally unnecessary, but an option for "feel good factor").

If you want one of these and can't procure yourself with a 3D printer near you, reach out to me via PM and I'll hook you up.

Here's some pics....

• 
  

Hello,
I need help from the experts here.
I'm starting a new project and have to find a descent Op Amp in DIP8 socket.
Thanks

I've been poking around Cortex M4 MCU datasheets for a number of years now, looking for the lowest power (uA/MHz) offerings. The primary purpose is to perform digital filtering functions - initially as an upgrade for SAA7220 in oversampling DAC designs. For a long while the best bang for the Watt in the general purpose space (excluding chips with fancy radios on-board which are normally rather limited in their maximum MHz) came in the form of the STM32F401/11 which take ~130uA/MHz and go up to 100MHz for the 411. The STM32G4 range arrived more recently and offers a higher top end and a richer peripheral set but roughly equivalent energy efficiency to the 411. STM32L4 manages to do slightly better at 110uA/MHz but tops out at 80MHz. Its 'low power' designation really comes from its low leakage rather than the energy efficiency of its CPU.

Over in the NXP stable there is the LPC550X (using Cortex M33 a newer design which is roughly equivalent to the M4) which delivers stunning numbers for uA/MHz. Until you read the fine print that a DC/DC converter is involved that is. So the currents are those drawn at the input to the DC/DC rather than what's drawn by the CPU itself. When that's taken account of, the device is still nicely efficient, in the 100uA/MHz region but the DC/DC converter is an unknown source of noise which I'd prefer to avoid if at all possible. Furthermore, its maximum clock speed is 96MHz. The LPC552X goes up to 150MHz but loses some of the attractive efficiency of its baby brother at that high clock. LPC54114 goes up to 150MHz with 17mA supply (no DC/DC) so that makes it about the most attractive NXP part. I haven't looked in depth at Kinetis branded parts recently but K24 headlines at 250uA/MHz so clearly not in the same ballpark.

There have been some Chinese vendors putting out M4s of late, GigaDevice was the first of these I looked at, GD32F303 runs ~200uA/MHz and is very cheap. However about 3 months ago I came across another part from a vendor I'd not met before, XSHC, as a very cheap (20RMB, $3) development module on Taobao. Being so affordable I felt compelled to check it out, however there is no datasheet in English as far as I'm aware. LCSC has stock https://www.lcsc.com/products/Microcontroller-Units-MCUs-MPUs-SOCs_11329.html?keyword=hc32f460
Wifey got hold of the Chinese DS and it wasn't too hard to figure out the uA/MHz from that - just under 100uA/MHz most of the way up to 200MHz. But it might not be an apples-apples comparison as the master oscillator current isn't included in that. Still at under $2 for the chip at official prices (cheaper on TB) and $3 for the module this has to be the winner. I just need to get a translation sorted out now.... The preliminary efforts I've so far made indicate it has enough functionality, including 4 * I2S, a TRNG and 192k SRAM though only 32k of that is able to run at 0 wait states.

<later> Attached first pass at translating the interesting meat of the DS, the outline descriptions of the functionality supported. Had to .zip it because .rtf isn't supported.
Development files here for Keil uVision use : https://github.com/ANYCUBIC-3D/HDSC_SupportPackage
Aliexpress purchase link : https://www.aliexpress.com/item/100...!sea!HK!2609685283&curPageLogUid=NDfczG45ooJ3

I plan to use 1/4" sheets of MDF/cardboard as forms (front and back) to create 1" thick boards for speaker sides.

What material would be good for the filler?

Concrete? Epoxy?

This would be used to create a rounded back for a speaker, using concrete forms cut lengthwise in half.

I have for sale 10 cartons of Peerless 832873 5.25" woofers with nomex paper cones. They are new and still sealed, packed 12pcs per box. I will only sell them by the carton for $480 each ($40/woofer) + shipping. Paypal add 3%.

What I want to show here is that when you use a resonant circuit to fix a speaker resonance, the negative qualities do not remain after the correction has been made.

Like electronics, individual speaker drivers generally are minimum phase devices (this doesn't include effects like diffraction which include a delay component).

The first image is a plot of response vs frequency. I have split a flat response into a bandpassed and a bandstopped component, and then combined them. This combined response is flat like the original.



The second image is a plot of time vs level to show any ringing directly, on the same circuit test points. Using a square wave from the generator, the upper and lower circuit branches show resonance effects from their filters. The recombined result is again a perfect square wave.

Hello everyone,
I have an old radio cabinet, that i want to turn into a speaker. Its inner dimensions measure roughly 33.5x24x58.5 cm. I have uploaded a picture of the box at the bottom of the post. Because its all in one unit, I assume a boombox type build would be best. Meaning 2 tweeters and 2 full range drivers. I would also like a woofer or mini subwoofer + a passive radiator aswell, shooting towards the front, since I'm a huge bass lover, however I'm not sure how the subwoofer would impact the rest of the build. I have been looking at a couple of drivers:

• Subwoofers/woofers:
  • https://www.soundimports.eu/en/tang-band-w5-1138smf.html
  • https://www.soundimports.eu/en/hivi-m6n.html
  • https://www.soundimports.eu/en/hivi-l6-4r.html
• Full range:
  • https://www.soundimports.eu/en/fountek-fe85.html
  • https://www.soundimports.eu/en/dayton-audio-pc83-8.html
  • https://www.soundimports.eu/en/markaudio-chr-70-champagne.html
• Tweeters:
  • https://www.soundimports.eu/en/grs-prt-8.html
  • https://www.soundimports.eu/en/dayton-audio-nhp25ti-4.html
  • https://www.soundimports.eu/en/dayton-audio-dsn25ti-4.html

As for amplefier boards, ive been looking at the following:

• https://www.soundimports.eu/en/sure-electronics-aa-ab34181.html?
• categories=audio_components&price=2.45-116.95~%E2%82%AC
• https://www.soundimports.eu/en/arylic-up2stream-21-amp.html
  https://www.soundimports.eu/en/tpa3116d21-bt.html

I have messed around with filters aswell, however I'm not a pro at any of them. I know some of the amplification boards have a separate subwoofer channel, and the sub therefore doesn't need a filter. I assume the fullrange driver doesnt need one either, but a bandpass filter would probably help.

I have made a lot of conciderations, however im still unsure. I would appreciate any help i can get. I have tried to select some drivers that look good together, because i probably wont have a cloth or anything covering the drivers (I love the looks of drivers). Do you guys have any guidelines to speaker parts, which ones are better and worse or maybe some sugestions for drivers you would reccomend yourself. I also apologize if I have done anything wrong in this post, since its my first post here.
Thanks for everything, Dudedek

These drivers were originally used by my son in his high school DJing years. We built Adire spec cylindrical housings made of 23" O.D. green sewer pipe and these babies rocked! Played less than a dozen times. Unfortunately, son moved on to a career path, house was sold and I had to discard the cylinder housings. The Maelstroms remain in great condition. I can provide pictures and negotiate payment methods. Asking $125 per. They are located in Delaware way down but can ship.
Andy

G'day Guys,

A question of power rating.

I have a resistor of 820R
Passing 0.017A
Dropping 13.94Vdc

I make this a power output of 0.237W.

This resistor is dropping voltage from the 37Vdc main supply rail to a 24vdc relay coil so the power will be continuous during operation.

I've tried deciphering the derating curves but predicting the temperature rise inside the amp chassis and the temperature rise of the resistor itself is beyond my understanding.

So. As a rule of thumb, am I safe to run a 1w carbon film resistor at 1/4 of its 1w rating continuously?
Assuming of course, that the temperature inside the chassis doesn't get obscene, which it shouldn't since this is a class AB amp.

Hello, I am wondering about a few mounting issues for transistors, resistors and heat spreader bars.
I am planning on mounting some filament regulator transistors (Coleman V9) to an aluminum bar 3/8" thick that will then bolt to an aluminum chassis. The transistors are plastic bodied. I will also be mounting an aluminum bodied chassis mount type resistor to the chassis.

Is there a need for thermal paste on these parts before bolting them down? They do not need to be electrically insulated I know.

Same question for the spreader bar to the aluminum chassis. Is a thermal past needed?

I am NOT planning on grinding the surfaces - just running the extrusions over some abrasive paper on a glass sheet. I also have enough Keratherm to use if needed. None of these parts are running over 100° F on a breadboarded amp with cobbled together thermal management techniques. (Bolted to some punched aluminum panels around 4 x 6 inches).
Thanks in advance.

Hello everyone,
I am writing in this forum to seek assistance with an issue I have encountered.
Recently, I acquired an SA-9900 amplifier—a machine that, in my opinion, is exceptionally well-crafted and reminiscent of a bygone era.
Unfortunately, there were some burnt output transistors and other damaged transistors on the final amplifier board (AWH037).
To ensure a lasting repair, I proceeded to replace all the transistors on this board. Since many of the original transistors are no longer available, I opted for equivalent replacements—choosing transistors with equal or superior parameters, such as hFE, maximum VCE, and VBE.
Now that the repair work is complete, the sound output is fundamentally correct.
However, I’ve encountered a problem: after some time of the amplifier being powered on, the protection circuit automatically triggers (the relay disconnects the speaker connections). Usually, after a few seconds, it reactivates.
I conducted some measurements and observed that the bias current, initially set on the amplifier, gradually decreases over time. When I measure the voltage between PIN 2 and 6 (as indicated in the service manual), I notice that the values drop from the initial 50 mV calibration to around 10 mV and occasionally even to 0 (at which point the protection intervenes).
Additionally, the initial calibration process is quite challenging because the values read on the tester (both for zeroing the output voltage and for bias current) appear highly unstable. A slight adjustment of the trimmer causes the measured voltage to deviate significantly from the initial value, eventually settling after 1 or 2 seconds.
I wonder if the choice of transistors (or a specific one) has influenced this somewhat erratic behavior, both in the biasing current and in the protection circuit.
Any help is more than appreciated !
Attached is the schematic diagram of the main amplifier board.

Thank you in advance,
Alberto

I need some small fullrange drivers (2.5" 3.0") to use them in my car, on the a pillars. That can work in a 0.2, 0.3L pod! I am thinking about the sb acoustics sb65. But the qtc in a small pod for this driver is 0.9. How bad will sound?

My second choise is peerless ne65w qtc around 0.7

I am planning to cross them around 200-300hz
What to do? I like the sb

Or what driver should i chose

Thanks

Hi all,
I'm looking to add ReceiverPI to my Raspberrypi with Pi2AES board as I need to do digital processing on the Pi side before sending the signal to an external dac.
However, I was not able to find any information if ReceiverPI allows that type of routing.
In short, the signal should always go ReceiverPI - > raspberrypi -> Pi2AES and should never bypass raspberrypi.
Is it achievable?
Which version of ReceiverPI should I get for that? proII or DDC
In addition, I would also prefer automatic coaxial\optical switching on ReceiverPI side based on an input signal.
If auto input switching is not possible can I use monitorpi pro for that?

note: Pi2AES uses HiFiberry Digi+ driver and is a masterclock
Digital audio stream will mostly be 96Khz 24bit or 48Khz 16bit (no dsd audio)

Thank you.

Anybody used a Sample & Hold curcuit in a DAC (after the I/V conversion, in front of the output buffer)? I have a pair of National LF398AH, does it make sense to experiment with it? I attached the datasheet. Perhaps its acquisition time is too slow for this application.

The Vox AC15C1 is their reasonably priced ($800) current production 15W circuit board based version and I
finally found a schematic for it here: I'll also try to attach the .pdf in case that source is lost.
https://www.tdpri.com/attachments/ac15c1-schematics-rev-2-pdf.291408/
Posted in this thread: https://www.tdpri.com/threads/vox-ac15c1-no-sound.570181/

There's at least one error in the reverb driver, perhaps more but overall a good job, by inkomodo.dragon
not sure who this is or if they are on here or not.

I've looked at the vintage 60s AC15 and thought that the Tremolo is way too complicated and it
would be a major cost savings to make it solid state which they've done in this design.
The Reverb driver and recovery is done with OP amps for another cost savings.

There's one OP amp in the main signal path that it looks like there's no need for, or it could at least
be moved so that it is in the Reverb path only.

Here's a discussion about this amp including some mods:
Remove the 330K in front of the volume pot in the Normal channel.
Change the tone stack values to those used in the JMI version.
He does one more that adds a "mid shift" switch but not sure how that's done:
Login to view embedded media
Login to view embedded media

I'm trying to build some diffusor panels in the style of parametric wall art but I'm trying to find a calculator to deflect a specific range of frequencies. Does anyone have any links?

Hello-
I am looking for advice/opinions on the feasibility of the following:
I am looking at putting together a 4 sub system using 2 AE dipole 18's and 2 CSS sdx12's in sealed cabinets. I plan to use dsp and 4 channels of amplification- not sure yet if I will go all mono or stereo. In any case, due to the configuration of the room, I originally planned to make h-frames for each of the dipole 18's, however, further thinking has me wondering if I might put them each in a sonotube mounted vertically facing downward, sort of a vertical round h-frame. This way, I could get the recommended 3' of space from the rear of the drivers to the nearest wall (ceiling in this case) and perhaps position them behind my Acoustat 6600's to use as a diffuser of sorts. Since I intend to cross them over at around 80Hz, I wouldn't have any resonance issues with a sonotube that was say, 3' tall. I could also perhaps put a slot on the bottom to make them into a slob of sorts....Any issues with this I am not thinking of???

I'm trying to measure FR of my phono playback system. I have a test record from Ortofon from 2016. It has frequency sweep tracks recorded with constant velocity.

Hypothetically, if these tracks are played by ideal cartridge through ideal RIAA preamp and recorded in Audacity, what is the expected form of the signal envelope? These are possible answers I could think of:

a) It would follow RIAA curve
b) It would be flat from start to finish
c) Something else

I already did such measurements with my cart and preamp, but the result is a bit strange, so I want to check if my interpretation is correct. I would appreciate your informed comments.

I'm looking to build some speakers for my desktop. I don't really have any tools but am willing to buy some for this purpose.
I listened to some active speakers in the store and was not impressed. (Kali lp-8, neumann kh120)
I also listened to some passive speakers with amplifiers in audiophile stores, but also was not too impressed. I find it hard to justify spending 500€ on speakers and 500€ on an amplifier which doesn't sound much better than random 100€ used speakers with a 100€ used amplifier. And I don't want to go used as I hate dealing with people and risk getting modly or broken equipment.

I'd like to power them with something like Schiit Rekkr or Schiit Gjallahorn. Something small, servicable, okay sounding.
I don't know much about hifi, but seems to me a lot of DIY stuff you guys do here is very efficient, with normal impedance of 8+ ohms, compared to store bought speakers which declare 8 ohms but are actually 3 ohms.

Should I look for a full range or a coaxial driver? My room is quite small so open baffle is out of the question I assume, so some drivers that work in a budget easy to build enclosure would be my best bet I assume.

Sorry if this is the wrong forum location to post this in. Open to any and all suggestions. Thanks!

Hi, ​

Looking for a pair (or 2) of 2SK2087C in order to build the Total Domination VFET (TDV) Amp from RA7 or similar amplifier that is using that output device.​

These are presently hard to find but most probably some of you have extra they will never use.

Please send me a PM if you have a few spare you wouldn’t mind sharing.

Thanks
Eric

Hello,

I have a Mark Levinson 436 that has 21 volts on the output.

Initially the amp had a slight pop when powering on, so I attempted to adjust the servo voltage with R1. When attempting to adjust it to below 100mv the reading was around 3.5 volts. Adjusting R1 would not reduce the voltage, but the voltage actually went up to about 4.5 volts, and would not go down from there. I replaced R1 which allowed this to go down to 112mv. It would not go below that, and now there is 21 volts DC present on the output/speaker binding posts. I have replaced all electrolytic caps on the VG board, but there is still 21 volts DC on the output.

Any help in finding the issue would be very much appreciated.

Thank you.

Why not recreate an ancient representative of the first integrated operational amplifiers and track down the developers?

Have a discrete op-amp at hand as a universal genius - and all this with exactly the components that you yourself consider to be the best at this point.
What could you /we conjure up from this? From an audio preamplifier to a power amplifier, to an active reconstruction filter for our countless D to A converters or even a sensitive, low-noise thingamajig for RIAA equalization - anything is possible!

Why don't we start a small dimensioning challenge,
at the end of which perhaps this year's DIYAUDIO (i.e. 2024) operational amplifier will emerge?

Here's a suggestion:

Fire away, but don't look in vintage data books and just copy - the topology is very well known and has been frequently integrated and sold as a standard, worldwide.


Kind regards and good luck,
HBt.

Clearing out some more shelf space:

26 drives EL12N stereo amplifier (credit to @andyjevans for the idea!)
2 chassis construction

26s are in filament bias with Rod Coleman boards
26s are transformer coupled
EL12N in triode, OPTs are Lundahl LL1664
Can add a volume pot, if needed

Power supply chassis with cLCLC for HV, first cap is a 4uf KBG-MN cap
Filament supplies are cLCLC, with the last choke in common mode
Rectifier is an AZ12

Not sure on price yet, make me an offer if interested!

So I'm repairing nad 3020B (yes unusual I know 😉) but when I took the lid off someone has replaced the switch. But in doing so, permanently shorted out out the live feed, disconnected the FET muting and switched the neutral

Small toy lm1875t
The simplest toy.
AC15-0-15

Selling a lovely sounding DI-16 DAC made by ECDesigns

It uses 16x Philips TDA1543 DAC ICs running in NOS mode, and a procedure called Direct Interpolation to avoid the use of an analog filter at the analog output.

This version has S/Pdif and Toslink inputs

Asking 325€obo, will ship worldwide

In preparation for testing the MT19CP-8 with my active amplification, I need sealed cabs for two of these. Does anyone in the USA have a serviceable pair of cabs with a front panel at least 10" wide?

Solid construction more important than cosmetics.

Preference for plywood.

Budget $250 USD

Posting to 02790

Not looking for it anymore, Project Changed.

Good evening, I can't decide between these 2 amplifiers. Which one of them is better and more reliable?

200eur for the Apocalypse
250eur for the Soundigital (comes with the remote)

Hey everyone... I've gotten my hands on an hifonics bxi4000d. It had some shorted output fets wich i have already replaced. It now powers up fine and doesnt go into protection anymore. However now whenever the output relays switch the output on, i get -83V on the output terminals. My suspicion is that the Gate drivers are dead.... The signal they give to my mosfets is Sometimes -12v or some horrible square wave with a huge dc offset. Sadly the markings of the driver ics are scraped off... Does anybody know what drivers hifonics might be using? Thanks in advance!

Kind regards,
Karl

I am looking for opinions on machines for cleaning vinyl records and especially on the two main methods used, namely, with cleaning liquid plus suction, or ultrasonic bath.
We share, with my oldest friend, a large collection of records, it is time for some of them to take a good shower.
25 years ago, I worked in a store that was a reseller of the Nitty Gritty brand. https://www.nittygrittyinc.com/
Extremely efficient machines, I see that the offer has multiplied over the years and above all, I no longer have the money to buy a machine of this brand.

Hi,
I use my Android phone with HIBY music Player or USB Audio Player Pro (both bit perfect with USB priority tweaks) to stream qobuz to my DACs. I have found several USB dongle DACs - you know, like the audioquest dragonfly, that sound good to me.

Some of these small DACs are pretty sophisticated: I have 3 R2R Dacs, one of which is 1-bit, one of which has a great FPGA. I have some delta sigmas with different chipsets which have their own characters. These all play into my home stereo right next to my turntable and standalone (old school bitstream DAC). I power the dongle DACs with a power brick (one of those fat mobile phone chargers) and use a USB hub to give them more power than a phone offers. I mention all of this because it sounds good and is pretty fun to be able to chabge your DAC every few days.

I am sure though, that a GOOD USB in and USB out reclocker between the phone and the DACs would be an improvement. Can you recommend such a beast ? if it has a powered USB out that would be bonus.

Most of the reclockers or USB decrapifiers tend to deal with i2s or convert from one connection type to another. I would be stoked if I could get this done with a USB c in and a USB c out with the magic done by the reclocker: (decrapifying, noise filtering, jitter reduction).

I don't want to overspend on the ifi galvanic USB or similar. they cost too much and do too little. I am pretty sure something pi related might be the best.

regards,
W

I saw an uncommon speaker enclosure design some time ago - here at diyaudio, I think - and would like to explore it further. But, for the life of me, I can't recall the name and haven't had any success searching for it.

Here's what I remember about it: The name of the design, presumably that of the originator, sounds European, possibly German. It has an opening at the front that starts as a narrow slit at the top and widens downwards with the sides curving away as something similar to a parabolic curve. There's a system of baffles and channels inside.

There was a link to what was obviously a scan of an old document. I've made a rough sketch from memory of what it would look like from the front. Can you please help find the reference again?