I have had the edge to get what I would call a good bench meter. I have plenty of digital handhelds, Fluke 289, Fluke 87V, Fluke 27FM, Agilent U1252A and then a Klein with an amp clamp of some kind that I generally use for auto stuff and where it will get dirty. I do have one bench meter, a really old Fluke 45. Not the highest resolution, but still dead on accurate. Kind of boring and it’s getting old, wait it is old.

I’m wondering if getting a bench meter is wise since I have so many other meters, but I guess I could sell some.

I really would like to get at least a 6-1/2 digit meter. I’d consider myself an extreme hobbyist. I love repairing and restoring old pieces and enjoy building diy amplifiers and preamps. I am guessing I really don’t need that resolution, but I would really like to have it.

The models I have been looking at are the Siglent SDM3065X ($745 USD), Keithley DMM6500 ($1600ish USD though it looks like directly from South Korea I could snag it for $1450), and lastly the Keysight 34465A. I also looked at a couple of used units, like on eBay there is a Tektronix DMM4050 that won’t boot for $385, but not sure I want to chance a repair on a unit that will have future screen issues.

So, the Siglent. It’s half the cost of the other two. That’s a pretty big savings. On the other hand it also looks like it’s lacking compared to the other two, there is a reason it’s so much cheaper. A huge plus for me is that I can purchase it on Amazon and pay interest free payments over the course of 5 months, $149 a month. That is incredibly helpful and may be the decision maker.

The Keithley DMM6500, personally I love this meter. I own a couple of Tek scopes so why not. I have done a ton of reading and it looks like the DMM6500 is fairly equal to the 34465A, but is less expensive and more people recommend. Plus I like the fact that the DMM6500 has a low ohm function, will be very useful for short finding on a circuit board. Honestly this is the one I truly desire.

The Keysight 34465A looks like a fantastic meter. It looks like it has a couple of shortcomings compared to the Keithley, but at the same time is better in a couple of ways. I highly sought I’ll be doing any data logging or anything like that. If I happen to find one that is used in good condition for a price that makes sense then I would pick up this unit over the Keithley.

I found one place at looks like I could pick up the Keithley and make payments through Klarna interest free over 4 payments, but it looks like the auto draw every two weeks, so $800 each month. If someone knows of a longer payment term please let me know. I could pay all at once, but spending that kind of money all at once, I’d get the side eye from my wife. Over several months, less of a big deal.

Anyways, looking for opinions on these units, maybe people that have used a couple of these have an opinion? What would you do in my situation? Financially it seem the Siglent would be the way to go, but it seems less “wow” and I’d hate to have buyers remorse wishing I had bought better.

Thank you,
Dan

DEVICE: Parasound HCA-2003 circa 1998 three-channel amp
SYMPTOM: 10+ seconds after power-up with no input signal being provided (i.e., @ idle), one channel's output voltage (as read by a DVM on the outputs) slowly starts to go unstable, varying somewhat sinusoidally several millivolts positive then negative, growing in magnitude to in excess of a couple of volts. (This, of course, can cause voicecoil over excursion/damage to a connected speaker.)
ROOT CAUSE TARGET CIRCUIT BOARD: With 100% certainty (after experiments swapping interconnects to/from other channel's boards and/or power supplies), I've isolated the culprit to be the Inputs Board. See pic. The right hand one-third of that board is the specific at fault circuit.
ROOT CAUSE TARGET CIRCUIT/COMPONENT: I simply don't know. I've A-B-C's each and every component across the three identical circuits (for the three channels) using only an ohmmeter and voltmeter. Have found all NPN transistors functioning OK, all PNP transistors functioning OK, all diodes functioning OK, all resistors very similar in resistance, pots all very similar in min and max resistance, all pot's resistance vary smoothly and similarly with rotation, all capacitors ohm'ing out very similarly.

QUESTION 1: What am I not doing that I need to do to isolate and verify what component(s) out of spec?

QUESTION 2: What additional diagnostic devices (scope, signal generator...) might be needed?

QUESTION 3: What type of component (i.e., cap, diode, transistor...) would you suspect in light of the symptoms?

There's some confusion about the G2 rating of this 6P15P. Some data indicates 330V for both anode and G2, while other comments suggests the G2 is "fragile" and should be de-rated, maybe down to 160V like the EL83.

So for those wanting to use this in triode e.g. in a PSE amp, how to proceed? A hefty resistor on G2 or what?

There's a thread on the 6P18P which contains some information but nothing conclusive. Francois G was going to test it but no further info. Maybe he can update?

https://www.diyaudio.com/community/threads/russian-6pi18pi-6-18-any-use.391138/#post-7146682

Dear diyaudio community.

I need your help with my RAKK DAC MK IV board, (version 2.1.) I use for my DIY DAC.

I would like to use the I2S input for the first time.

My plan is to use the I2S over HDMI board from Ian Canada as input.

This offers MLK, SCK (BCK), LRCK and SD (Data) as outputs.

Unfortunately, I do not have any information on the assignment of the 10-pin connection block on the RAKK DAC MK IV board.

Does anyone know the pin assignment of the connection block?

I would be very grateful for any help.

Unfortunately, I cannot reach the developer of the RAKK DAC, David Davenport, by email.
He seems to be retired and I only have his work email address (from Raleigh Audio), which is apparently no longer active.


Cheers, Niels

Ok so i always see the bracing that goes from a panel to a front panel like inside a horn

does that needs to be like that ?




can you just brace like i saw on some 2000 era Yorkville's
LS608's to be exact

they use like a 1" by 2" wood sticks in the corners
like the below

does that augment the corner structural integrity if you drop it
or the roadies abuse the boxes ( like always )




and what about mid panel bracing like this that i found inside the yorkvilles
in L shape



can we get away with no L bracing like the below




and my question is.... do you really need to do the bracing like the below ?
or with the L braces along wide areas in the panel when flex occur you can be ok








also can you make it with single baffle wall or use double baffle wall

Hi. Does anyone recognise the capacitor in the picture, marking S7Jr .. isn't that a Polymer Tantalum cap ?



Oneminde

Hello community,

i am a new member of diyaudio.
My goal is to build a diy pc audiosetup starting from scratch, with the pcb and the speakers.
I am not new to electronics, i made 2/3 years in school and work in an environment where electrical knowledge is required, but am a complete noob regarding audio stuff.
So i signed up, hoping to learn some new stuff and getting help for my little project.

Hello all, I am in Scotland and have had the same amp audio lab 8000a and mission 763 speakers since I could afford a hifi system and have been very happy with it until now

Hi all.

Please bear with me, this is the second account I have created as my main account was flagged as a spam bot.
I sent an email to request it to be re enabled 16 days ago, as I believe this was an error, but had no response as of yet.

I apologise for breaking any forum rules to create this second account, but I would appreciate being allowed back onto the site with my main account, or at least be able to discuss why my account was banned for asking a question about designing a speaker enclosure for a open source project I'm working on.

Kind regards
Ben Jackson

I bought a used Anthem PVA-7 amplifier, knowing it was not working on 6 of the 7 channels. I have reversed engineered the working channel (no schematic) and have all 7-channels working. As I was cleaning it up, I got to looking at the fuses (only 4 rail fuses the other 4 were missing) and I have some reservations to their rating.

The main fuse coming in was a 15A fast-blow ceramic, but the board clearly states 15A slow-blow on the PCB - so I have changed to a 15A slow-blow ceramic fuse.

The power rails, +/-55Vdc, has a pair of fuses for each Heatsink (three heatsinks have 2 channels and the Center is a single channel on a heatsink). In the amplifier the Center (single channel h/s) and one of the Dual channel h/s boards came with 15A fast-blow ceramic fuses. I question the amperage and being fast-blow type, not to mention they look brand new (red flag). While I was repairing and testing to make sure I fixed everything, I used 6.3A slow-blow fuses. No trouble but I have only repaired and tested/listened at low volumes up to this point and I don't want to blow single/both fuse(s) when I give it a real test.

Any one know the specific amperage/style rail fuses that should be installed? Are the 15A fast-blow ones correct? The amp has speaker, over current and voltage protection so the fuses seem to be there in case of catastrophic failure in one or both of the rails.

The amp is a 2-pair (2SA1302/2SC3281) TO-264 output per channel and I currently have it biased at ~25mA per channel and the h/s is slightly above room temp. after 2 hours of low volume music (~5 watts), with no more than 10mV of DC offset, running at +/-55V rails, with a 40-0-40 Vac rated at 8.8A transformer.

These coffins sound very good indeed but boy they do look **** !

Can I call them Rogers Pro 9TL’s ?

Hey, I'm Ismael and I like headphones and audio and building stuff and learning more stuff and want to share my experience with and learn from more experienced members!

I’ve got a 2 watt DIY SET amp built on the Decware zKit Schematic (including the anniversary modifications/bypass capacitors)
https://www.decware.com/newsite/ZKIT1.pdf

I’ve been using this amp for about three years and when I shut it off if the source is still playing the music fades out over the course of 10 seconds or so and starts to break up before going silent. The last couple of weeks I have noticed that it started cutting out instantly when switched off. Yesterday I switched it off and it cut out instantly; I changed interconnects and turned it back on. The tubes lit up and everything looked normal but it wouldn’t produce any sound. I let it sit about 10 minutes and tried again. Still no sound. I powered it on today, about 16 hours later, and it is working normally again. Anyone have any ideas on a diagnosis for these symptoms?

Hi First time here I am looking for .laser player VAU1254/01 mine doesn’t work anymore ,does anyone wherry I Can Bey it. Gr Frans

Good afternoon.
My name is Carlos and I live in Zaragoza, a city in Spain.
I am a fan of audio and video (movies and concerts)
I hope to be able to contribute something and learn a lot in the forum.
Best regards

Hi all,

I'm currently working on an 'effect' to have adjustable amounts of second order triode distortion. Here you can see the schematic of one channel:
The input OPA amplifies the standard -10dBv to ~11Vpp. This is then fed through the 12-position stepped attenuator P1 giving 11x 4dB steps. The attenuated signal is then fed towards the grids of a paralleled 6SN7 and afterwards again attenuated by P2 to give an overall gain of 1. In the first position, the grids-stoppers are shorted to ground and the input signal is directly fed to the output OPA.

This gives adjustable ~0.05-5% of second order harmonics while keeping the loudness the same.

Here you can also see the layout, in the first image coloured according to the layers, with red facing upwards to the tubes and blue facing down towards the components. In the second they are coloured red for cathode, green for anode, green for grid, blue for heater, magenta for ground and cyan for input and output. The PCB will have a four layer stackup with both inner layers filled with solid ground planes:



I'm now wondering if I have overseen something in the schematic or layout. Specifically, are R3, R4 and R16 necessary? Should I try to make the green traces shorter?

Best regards

Dominic

Hi, I'm not much of an expert on audio, but after 55 years of owning audio equipment and reading the consumer magazines I ought to know something. I joined because I found a post by googling that may solve an issue I have. But I also have a tweak I think everyone can use that I willl be sharing.

https://western-electric.squarespace.com/s/375A.pdf

Anyone have any experience with this one? Theyre not super expensive, and look interesting as a driver....

Why does that resonace stick out so much where there was previously a big cancellation at the full wave length between the front and rear of the driver in the upstream section?

360/90 is 4…. So it’s filling in the cancelation notch just briefly at 96 hz or so?

Hello

I have few types of Toshiba and Sanken transistors. These are new-old-stock from Polish distributors and 100% original, not from China.
Price is for complementary pair.
Please contact me for shipping - I will calculate.

For different types or grades - please contact me as well and I will check.

Toshiba:
2SC5171 + 2SA1930 - $1.50
2SC4793 + 2SA1837 - $1.50
2SC2240-GR + 2SA970-GR - $1.50
TTA004-B + TTC004-B - $1.50
2SC5198-O + 2SA1941-O - $3.50
2SC5200-O + 2SA1943-O - $5.00

Sanken:
2SA1859A-Y + 2SC4883A-Y - $3.00
2SA1668-Y + 2SC4382-Y - $3.50
2SA1186-P + 2SC2837-P - $4.50
2SB1647-P + 2SD2560-P - $7.50
2SA1492-Y + 2SC3856-Y - $8.50
2SB1560-P + 2SD2390-P - $11.00
2SA1216-Y + 2SC2922-Y - $12.00
2SA1295-Y + 2SC3264-Y - $12.00

All the best, Robert

1 Reclockpi, new and unused

50€, will ship worldwide

Hey All,

How to repair this sub broken tinsel lead ? I cant reach the broken spot on the cone from the cage to try resolder. What other options do i have ? The sub is still good shape but that tinsel lead is not..



Appreciate your input..

As title, not used in a couple years, but can't see why they shouldnt be fine, sadly I cannot test them.
No idea of value.

I have a pair of nice amorphous SE OPTS made by NP Acoustics which are now redundant since I've made other plans. They're very detailed and well run in. Outputs for 8R and 16R. Up to 90mA current. Bottom photo shows the type of OPT not my actual ones, measures 10x10x10cm. Mine are black. Quite heavy, like 2.2kg each. One transformer has a slight blemish as shown on the corner. There was some dust on the top but I just brushed that off.

Going for £185 from London UK. Andy

I swapped out some caps on the my 3 way towers. You'll see in the pictures which ones I changed. I also revised the notch to take out a little more of the cone breakup.

Female vocals sound overly bright to me now. I am considering swapping back in the elctrolytics. I really only changed caps on the mids. The tweeter already had poly caps on it. Is it possible that I prefer the duller sound of electrolytics? I did compare sound back to back and found the poly caps sound cleaning. Now that I've spent a week listening to the new caps I find them to be a bit bright for my tastes.

Do the poly caps need to burn in for "x" amount of hours before they sound right?
Is it possible I just don't like it because I am used to the other XO?

I do have multiple other systems in my house. They all use electrolytics. They do not have the same brighteness

Details:
1. All of the other caps are ClarityCaps poly. All except the big one on the woofer. That one is still electrolytic but I added a poly 1 uf coupling cap to it.
2. Other than revising the notch filter none of the values have changed.
3. Yes, I did solder them back in correctly, I verified this as I thought maybe I screwed up.
4. The two variations measure exactly the same. Within 2 db
5. All data in vituixcad is measured data
6. Drivers used are: Hivi Planar tweeter, Zaph mid 5", Peerless woofer 8"

Maybe I am missing something here.

I cant identify these 4 chip.
Any help will be appreciated.

Thanks

Hi folks,

I understand thickness of at least 5cm for this 1/4 wavelength, however, what material would you recommend to glue at the baffle edges, considering that I'm using for some sort of aesthetics. What about these polyurethane foams. You can see the simulation.









What about using these? Is the shape important?

It's suffering from the usual crackly volume / input selector issue which is not too bad, it's still usable.
Today when switching on, there was a bit of hum initially that then disappeared (set to a line-level input), which makes me think maybe it could do with a proper refurb, particularly all the electrolytics are still original.

Edit: I found https://www.amprepairservices.com/contact he looks very knowledgeable.

I might open up the PSX myself and test it under a dummy load, to see if the smoothing caps are OK, and ask him to look at the Cyrus 2. I guess a good way to start is to look at the time-constant of the +- rails into a dummy load, removing one cap at a time.

For sale is the following almost finished easy project to build a super nice DAC:
-Twisted Pear Buffalo III-SE-Pro 9028 DAC with all the good regulators (new price $459, http://www.twistedpearaudio.com/digital/buffalosep.aspx)
-Mercury I/V stage (new price $169, http://www.twistedpearaudio.com/linestages/mercury.aspx)
-Placid HD BP Power supply for Mercury (new price $95, http://www.twistedpearaudio.com/power/placidbp.aspx)
-Arduino DUE (New price ~$50) with Hifiduino TFT Pro v1.09 software programmed (https://www.dimdim.gr/arduino/tft-hifiduino-pro-project/)
-DimDim Universal signal isolator (https://www.dimdim.gr/arduino/universal-signal-isolator-shield-for-the-arduino-due/)
-Rotary Encoder board + encoder (with led) to control power on/off, menu, volume
-Nice 4.3" Color TFT screen
-Audiowind A-270 regulator to provide power to the Buffalo Board
-Twisted Pear CMP1 S/PDIF level converter kit
New price of the parts is ~$1000

I'm selling the complete package for 330 EUR firm + shipping. I'm shipping from Finland, Europe.

What is still needed to finalize this:
-Transformer to feed Placid HD BP Power supply
-Transformer + rectifier or another power supply to feed A-270 regulator board
-Enclosure
-Connectors, etc. small parts
-Wiring
+ whatever options you want to have, like amanero or similar (not mandatory)

See attached photos and the linked video of the action: https://photos.app.goo.gl/uJM3o9JnfWE8aFxM8

BR, Sami

Hi all.

I'm very interested in Tony Gee's Plutone speaker.
I have problems finding any reviews of them.
Do any herre know if there is any review of these speakers?

Thank you

If anyone out there has one of zenmods XA252 kits and situation has changed, and would like to sell it, please let me know! I destroyed one of my boards and really miss this amp!

Thanks,

Russellc

While slowly working on my other MEH projects, I just noticed the Ikea Kallax in front of myself and I just thought it would be cool to fit in a synergy horn there. The internal dimension of the kallax cell are 330 x 330 x 380 mm, so the speaker must fit into this volume including wires in the back. This is nothing new, it has been done before, e.g. this one by aragorus https://www.diyaudio.com/community/...-6-5-coax-in-a-reflex-box.353906/post-6190455 would most probably fit the shelf.

Coaxial is the obvious option, but I would like to try if I can fit in the GRS PT 6816 planar tweeter in there...

And if necessary, I can add a bass unit to a shelf cell below. Not that I would necessarily use the speakers inside the shelves, but it is a quite handy size and a bit of a challenge🙂

Has pukydawgs.com gone out of business?

Folks:

Please forgive what may well be a very dumb question, but I do need some advice. I am planning a Noval Aikido preamp project and have a power supply question. I have two Hammond transformers on hand -- a 369JX (50VA, 500V C.T. @ 69 ma and 6.3V C.T. @ 2.5A) and a 166L6 (12.6VA, 6.3V C.T. @ 2.0A). I understand the Aikido needs more heater current than the 369JX alone can supply. Can the 6.3VAC secondaries on both transformers be connected together at the power supply? I have attached a copy of the power supply circuit; the power supply board itself can be found at https://www.ebay.com/itm/144817864498

Regards,
Scott

Hi
I built a full bridge SMPS with IR2110 + boostrap capacitor + old mosfets as recommended, which works fine, but I would like to replace the old mosfets with GT60N321 IGBTs, add a totem array, remove the boostrap and add an isolated power supply of +14VDC and -4VDC to get rid of the Miller effect.

Simply replacing the old mosfets with IGBTs also works, but according to the oscilloscope I see that it would be a good idea to add a totem array and adjust the power supply for the output side of the IR2110. For the power supply of the upper and lower sides, they will use isolated converters designed for driving IGBTs with outputs of +14VDC and -4VDC.Is it possible to keep the IR2110 driver and connect the IGBT and totem array using isolated converters in this way ?
I will adjust the Deadtime only after the circuit with isolated converters and IGBTs works.
Thank you, samponek

Hi,


I have an old Sennheiser VKS 203 in very good esthetically and working shape.

Unfortunately, the front input selector line has an issue and because of that the signal coming from the preamp part is not equal on both channels.

Can anyone help me with a part or a contact for repair? Thanks.

All the Best from Hungary,
Arthur

I have blank tubelab spp PCB and some tubes to sell.
PCB - sold

Used Matsushita 12AT7 measured pair 14usd

Nos Toshiba 12AT7 pair 20usd
(Hi-s version - selected items)
Used Matsushita 6BQ5 measured two matched pairs 55usd

+PayPal fee 4% or frieds family option
+ Shipping 15 usd with tracking number

Hi, as new member I would like to share my repairs and lessons learnt as well as learn from other members.

After and during the COVID period working from my home disk I missed my audio gear from the eighties for a proper music experience. As such I started to acquire new stereo equipment form the 70s/ early 80s around built quality went done.

As some of these equipment required repair or restoration I started the hobby of repairing equipment, solid state as well as tube gear.

Regards, Werner

Has anyone had experience with the power / speaker switch on Pioneer SX450 receiver? The switch has these positions: Power Off, Speakers A, Off, Speakers B, Speakers A+B. Starting the amp through my dim bulb from Off to A, the light stays bright and a hum is heard through the speakers. If I turn the knob to the next Off position then back to A, the bulb dims and it works fine. The receiver sounds fine. I suspect there may be an issue with the switch, but it's a very fiddly thing to pull out so wondered if there are any other thoughts about this out there.
Regards John L.

https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/SDR-960/SDR-960-Spec.pdf

Hello!

May I ask for help to optimize a MW SDR-960-48 SMPS here?
I chose this power supply to feed six TPA3255 in PBTL configuration for a cheap trick 2x3 way active setup.
Powerwise the SMPS should be more than sufficient, so no problem there.

Even though, the SDR-960 is of good reliant quality and miles ahead of most noname SMPSs, some may claim that the ripple could be better (it's <1%), not sure if this is a real problem at all or a theoretical paranoia phenomen.

However, before making the layout for the amp case, I wonder what kind of optimization could be worth to implement.

1. Additional EMI filter on the 230 AC side?
2. Additional buffer with 63V / 10-20.000 uF caps at the supply 48V side and or additional filters?
3. Any other thoughts how you would optimize it? Or just go and relax?

Thanks for your time and input in advance! 🙂

Rather than open an old thread and necropost I'm starting another.
Without wanting to be morbid I'm not getting any younger [ mores the pity] and I am writing a new will and pre-planning my funeral.
As part of that I am chasing a recipe for a very strong dark beer to drink on the day.
I'm not of a religious persuasion and if asked I always tell folk I'm a pagan and believe in the dark artz.
Anybody got any good recipes for a bitter-sweet stout of as strong a strength as possible?
Something like Theakstons Old Peculier but sweeter and stronger approaching 12% or better, a "**** & Raisin Ale" perhaps?

I see some development in this area. Is it already possible to use a diagram (format X) as input for a PCB (format Y)? Is it available for DIY (public domain or low cost…)
I guess this could shorten the time of PCB development.

Regards, Gerrit

Hi all,

Just a quick question regarding cathode bias voltage and, in particular, stability.

After catastrophic failure caused by an overused output tube (runaway cathode voltage). I rebuilt the amp and installed meters to indicate what the cathode bias voltage was on the KT66's (as pictured).

Generally, they do vary slightly (albeit always 1v apart) but occasionally, the left channel (blue) will skip very quickly between 38v - 39.5v. It sort of cycles from 38v then jumps quickly to 39.5v then back down, then back up. This happens over a few minutes and all the time the right channel (red readout) is stable. After a few minutes, it becomes stable too.

Happened today shortly after switch on, yesterday after about 2hrs use.

Schematic attached.

I have for sale the following drivers from Tang Band in new condition:

10 units TB W5-1374SB 34€/unit
2 units TB W5-610SG 40€/unit
2 units TB W7-337S 45€/unit
2 units TB W4-1263SC 30€/unit
Check pictures attached...
Payment by paypal

Selling 1x pair of LT DC filament supplies, designed by Ale Moglia
More info here: https://www.bartola.co.uk/valves/for-sale/dht-lt-supply-pcb/

Including 2 populated and working/tested boards, with common mode chokes installed and 2x pair (4 total, only 2 pictured) of hammond 159ZE 28mH/3A inductors

125€/pair, ex worldwide shipping

Yesterday I sold succesfully the overhauled Basis '95 - 2023 to a happy new owner in Helmond.

https://www.diyaudio.com/community/threads/re-built-vifa-basis-95-2023.395894/page-9#post-7490956

At the moment I'm playing again (after 15 years, {bought back} for a fraction) with my old self made Odin's MkIII built in 2007 (sold in 2008) 😍.
First project ever built good DIY speaker.
Very nice!

The story:
The new owner from 2008 contacted me about 2 months ago and told me that he wants to sell my speakers after 15 years listening music with pleasure.
He asked me some advice for a good description for his advertisement text on the internet.
But I was thinking....... this is unique......I like to have them back in my house / listening room....... full of good memmories with this speaker!
We make a deal and now they are back here in my living room again and still playing as good as in 2007.😍😍

Just curious about what the other guy's workbench looks like?
Well it's pretty sad but here's mine.
leftovers, trashcan fodder, blown speakers Etc. Etc.

OK we could call this thread the wall of shame. Be a man, step up and show us just how twisted you are.

Has anyone routed a rebate into the insides of the side panels as per (I think) the flat packs. ?
I'm building from scratch and could just glue them in place, but thought about trying this.
I only have basic diy tools and can do one side easy enough probably, but what would be the easiest way to mirror it perfectly on the other side?
Short of a lot of measuring and marking, is there an easier way?
Thanks..
Rik

Up for grabs are my brand new and unused D28 af Tweeters ( D2806 2A )

This is for the pair ( not splitting)

£250 + p&p

Up for grabs are my used D28/2 ( 81466 ) tweeters , both are working perfectly and were removed from my Ruark Accolades .

£180 + p&p

I bought one of these devices from Aliexpress. Technically, the use case isn't audio - it's radio - but I thought you might be interested in this quick review.

My main goal was to find a decent power supply with the following requirements:

• 5V @ 1A (and I need 0.9A of that)
• Low switching noise (so either not a switcher, or very low noise)
• Under 100mV ripple (which probably isn't low noise by audio standards)

It turned up. Superficially, it works. 5V comes out, no fire.



Internally, it's made up of a 2*110V to 2*7.5V transformer. The two primaries are wired in series for 220VAC operation, but typically my mains voltage is around 245VAC here. The switch is single pole. There is no dedicated fuse, although the transformer appears to have a thermal cut-out. There is no connection to earth, despite being metal cased.

That goes into a full wave rectifier and 3300uF and 100nF capacitors. After that, an LM317T regulator, with 2*1000uF, 2*220uF and 100nF capacitors.



Output regulation is acceptable up to around 0.7A. There's quite a difference in behavior between when it is first turned on ("Cold") and after it has been loaded for a while ("Warm").



Ripple is relatively well controlled at lower currents but gets pretty wild later. At 0.7A it is around 5mV. By 0.8A it is 235mV. At 1A it is 660mV - although from time to time, when warm, it gets worse.

When connected to a USB device drawing 0.9A with a switcher inside it, you get a horrible interaction, with the voltage dropping and the current increasing. It ends up oscillating.

As expected, on the spectrum, the 100Hz is the fundamental with several harmonics.



It also gets warm enough to emit that warm plastic smell...



All in all, I would not recommend this device.

I had these cabines ready for a new project but I really have no time to build anything right now, so, I will put for sale if there is any interest.
They a Sonys Faber Electa Amator stye anf fuly built in solid Cherry wood. Fully new.
THe cabinets were made for Swans HiVi M1 kit but can be easily modified to your project.

External dimensions (cm) 21 width x 33 height x 26 depth. Wood thickness 22mm. 11.2 internal liters.
The current holes for drivers are:
Tweeter 120mm diameter (90x75mm cut off originally for the HiVi RT1C-A Tweeter)
Woofer 115mm depth. Ready for 5" surface mounted midwoofer. (Hivi F5)


Asking 250€ for the cabinets. Shipping to EU will be 20 to 25€.
Will be sent in their original packaging


https://ibb.co/GnHgVFW][/url]

https://ibb.co/1RN8MSK][/url]

https://ibb.co/Vm54SK0][/url]

https://ibb.co/x5yzMPY][/url]

https://ibb.co/nmV1NZY][/url]

https://ibb.co/1b51gRP][/url]

https://ibb.co/PG8qwf8][/url]

https://ibb.co/T1rkxTz][/url]

https://ibb.co/phMtFmw][/url]

https://ibb.co/TvnZndt][/url]

https://ibb.co/jTymDxd][/url]
https://ibb.co/rFXjVZG][/url]

Very often, diyAudio is very slow, especially with images and videos.
From France, 100MBit connection.

I am using a few 12V switching power supplies for heaters of my DIY tube amps. Because the heater resistance is too low, some of them will not start. Two of them blink for 10 - 30 seconds then run normally. I assume the blinking is due to current limiting of the supply. My question is whether start-up blinking will cause premature failure of the supplies or hurt the tube heaters?

Hello,

my friend gave me a PM80 MKII amplifier.
I want to use it with my Bose 901 VI but I was not able to do the right required connections.
Is it possible to add Pre-Out / Main In in the amplifier ?
Someone did it ?

Regards

This is a line/headphones preamplifier with no global NFB used, but still with very low distortion.
First stage is input gain stage with variable gaain
Secon stage is a buffer.

Here is description of first/gain stage.
It started as GainWire CFA preamplifier, and I decided to redesign it in to a non global NFB preamp.
The gain is set to 4 times at the rheostat P1 value of 10k and it's calculated as P1/R19.
It uses a current conveyor as a gain block.
SNR does not change with the gain, so it is the same for low as it is for high gain, as the input signal is never attenuated, signal noise ration stay the same for all gains.

Gerbers are here: https://www.diyaudio.com/community/...ne-non-gnfb-preamp.395695/page-3#post-7733838

I recently had the good fortune to find a used Threshold CAS-2 at one of my local high-end audio stores. It has been a pleasure to listen to and learn about the history of one of the earliest Threshold designs from the late 70s.

The unit was well cared for by its previous owner(s). If anything, it may have been in clean storage for a few years. Initial power up resulted in a significant amount of mechanical 120Hz hum from the internal power transformers. This subsided a little over the next couple hours as I let the amp come up to temperature. There was also a small amount of 120Hz hum present from the speakers, but this component was not noticeable at my listening position. Initial listening was good, with a noticeable amount of brightness to the tonal balance. The brightness mellowed out slightly over the next few hours of powered operation.
I switched to a Transparent power cable for the next day's listening. This power cable is an earlier 1.5 meter model that has three lumps of filter network along its length. I have used it in the past with amplifiers that had sensitive power transformers. The Transparent cable did its job once again, and both the mechanical hum and audio hum were noticeable reduced. Listening to the amp with this configuration proved to be a lot of fun. In many ways the CAS-2 reminds me of my old olive era Naim NAP250, in the best of ways. The CAS-2 is lively and engaging, with a distinct sense of Pace, Rhythm and Timing, as Naim aficionados like to say.
Over the next two days of listening sessions I found the amp to sound better integrated over the whole frequency spectrum. The imaging solidified as well, and there started to be a better sence of the distinct harmonics of acoustic and simple electric instruments. The bass developed good extension and definition, sometimes calling more attention to itself than I am used to on a few recordings, though this feature also mellowed slightly over time. The amp definitely sounds its best when it is left on for a few hours, so I started leaving it on all the time. The case gets just slightly warm after a full day. This is not a Class A design, but a moderate high bias class A/B. It appears to be an excellent match with my newer Vandersteen 3A Signatures, with plenty of power available for good control. The dynamic presentation seems to be better with the CAS-2 than with my DIY M2x. I have enjoyed revisiting a number of my favorite recordings to hear them with a better set of dynamics.
The CAS-2 also compares very favorably with my DIY F6. The F6 has been something of a test bed lately, as I was experimenting with some alternate Mosfets in the output stage. The sonic comparison with the CAS-2 led me to re-think some aspects of my F6 modifications, and I intend to try some new ideas to help the F6 provide some of the same rhythmic enjoyment that the older amp seems to provide with ease.

This design is a refinement of one I designed and built about 15 years ago. In most respects the front end is not that unusual, being a derivative of a Krell front end. The most unusual feature is the use of separate feedback loops for the voltage gain and output stages. If there is interest I can post additional details and a circuit description.

The electronics have been designed and simulated, and the PCBs will shortly be arriving. I'll be posting some photos of the mechanicals: no acceptable chassis was available, so I had to fabricate one from scratch.

Jeff

After over 43 years my Oracle turntable was in need of a refurbishing. The Papst motor was getting noisy and I was unable to fix the problem. A replacement motor was unavailable, so the next step was to replace the motor and motor controller. This entailed some electrical design and quite a bit of mechanical design and machining. The first attempt utilized a Maxon DC motor with an optical encoder feedback loop. Speed stability was fine, but the motor noise was unacceptable. Mitigation efforts were only partially successful.

The second approach used a DC brushless motor and a Maxon controller. Some motor cogging noise remained, but the addition of sound deadening polymer (Sorbathane) eliminated that noise. The controller speed is set by a DC voltage, so the auxilliary electronics are limited to generating the DC levels corresponsing to 33.3 and 45 RPM and producing a 60 Hz strobe signal to an LED. The latter makes it easy to calibrate the TT with a strobe disk.

Jeff

Cast into a humble & simple question....
Gave away my Horowitz & Hill to my nephew (somesort of my clone actually), I'm stuck into how to calculate the final compound transconductance of a Sziklai pair consisting of a J-fet and a BJT. Any clue upward pointed appreciated.

Ive decided that I want to upgrade and try the best sounding midrange I can find. what is the best sounding midrange you've worked with or heard....
my current mid is a peerless 830883 6 1/2 mid. hope to upgrade from this

hello all my name is Mantas im from lithuania

New member here, 58 yrs old. Also a musician of many years with plenty of stage experience. Always been into all things electronics since middle school. In fact, in high school a friend and I cut a guitar cable in half and he took one walkie talkie apart and I did the same to the other. He unsoldered the microphone and soldered the cable in it's place. I unsoldered the speaker on mine and soldered in my half of the cable. When we put them back together he taped the microphone button on and plugged it into his guitar. We then plugged the other cable/talkie into his amp and put it speaker facing out his bedroom window. He walked all around the neighborhood blasting his guitar to all the neighbors. We had a huge laugh when the local truckers CBs came through the amp and so did the neighbors. 😆😆Nobody could quite understand how we created a wireless guitar system back in the mid 80's but it worked! Sorta. I like to learn anything I can so here I am in the DIY Audio Group.

I've got a 8" woofer and a CD + horn. I've used DSP with delay to time align drivers before, and liked the result. So for this passive build I thought I'd try to get the acoustic centers aligned physically.

So to investigate what that would require, I set up some boards between 2 tables so I could hang my woofer and then my tweeter at the same vertical location, facing up. I set up a mic above, pointed down and didn't move it between measurements. Then I measured with REW with a timing reference channel, and that told me the distance (acoustically) to each driver. Then I just gotta make my baffle so that I can line 'em up...

Looking at the woofer and CD+horn I thought it would be pretty close. The measurements suggest otherwise... =\ I've got the Tymph AULA02014 8" woofer and the Celestion CDX1-1446 on a JBL / Selenium HM17-25. I have a thread for those drivers here: https://www.diyaudio.com/community/threads/tymphany-aula02014-0006-pe-buyout.416365/ but this discussion is to focus on baffle structure ideas.

REW thinks the tweeter is 70 mm behind the woofer. To line them up I need to bring the tweeter forward rather than back, and by a fair 2.8 inches! Now, I've seen the dual chassis type of horn build, where there's a box with a big woofer in it, and then the big multi-cell horn leans over the front of the box, and that achieves a horn-forward type of build. I kind of had a more visually discreet aesthetic in mind. The HM15-25 isn't a huge monster, I had imagined mounting it in the box / on the baffle. XO is expected to be ~ 2 kHz I was hoping to keep C2C distance from becoming enormous, but also don't want to put a big diffraction object right near the woofer.

Has anyone made / seen an elegant horn mouth fwd of woofer type build? I'm looking for ideas.

- A

Sold.

Hi,

Looking to buy the following NOS genuine transistors, matched if possible:

2SA1986-O, PNP, 230V, 15A - Qty 30
2SC3558-O/R, NPN, 230V, 15A - Qty 30
2SC3478-K/U, NPN - Qty 10+
2SA1376-K/U, PNP - Qty 10+
2SC2705-Y, NPN - 10+
2SA1145-Y, PNP, 150V, 50ma - Qty 10+
2SC3790-E/F, NPN - Qty 5+
2SA1480-E/F, PNP, 300V, 100ma - Qty 5+
2SC4685, NPN - Qty 5+
2SA1507-S/T, PNP - Qty 10+
2SC3902-S/T, NPN - Qty 10+
2SK330-Y (1.2-3ma IDSS) - Qty 5+

Please let me know by PM

Thanks
Do

I opened this up to work on the switches and seen the 3.3K resistors that are in series with the inputs. I am trying to figure out the reason for those resistors in a passive switching device.
Any ideas?

I am a retired VW tech and now working at a machine shop in Abilene TX. Trying to teach myself something new.

I have a couple of hundred to match.But how close should they be matched?
They are for discrete headphone and amblifier,

Well, I gone and done it! in Austria when you have a child, you get four weeks off as a father to stay home and help out.

Since our new son came into the world at the beginning of November, I’ve had some time off, and decided to finally throw together a 45 amp, without all the bells and whistles that I normally would use. There’s no Coleman regulators, no fancy, expensive output transformers, no solid state help.

It’s relatively simple, AC heating, a 6SL7, and only parts that I had in the junk box. I think it turned out great, I’m really impressed, I had never actually tried AC heating in all my years of building….

I was going for that 1950s industrial look.😎🤞🏻

Any opinions on Beyma CP-755Ti vs. 18sound ND1424BT, both 1.4" titanium drivers?

Both versions are for operating without mains power supply - just two secondary D-cells are in use.
What is the difference ?

BTW - the mains supply version uses the additional term "AC"
The difference is the year of release - the suffix "DC" means a newer series (release 1976) than the older series without that suffix (release already 1974) go to
ハイファイ堂メールマガジン
Who know the difference between the gain stage circuits of this both versions ?

The schematic of the JC-1DC (potted version), which I have create some years ago, you will find in post #8 below.
Maybe there is also a schematic of the JC-1 anywhere. Simplified schematic you will find in post #32 so as some hints concerning the question from headline.
The last both pictures in post #12 are from a device in not worked condition at left channel - unfortunately also in a potted version. The replace of electrolytic capacitors by new ones don't provide the wanted success.

Looking for a ~5.5" mid and I see the Faital Pro 6RS140 being spoken highly of. For example, Troels uses it in his Loudspeaker center and raves about it. My problem with this (and other Faital drivers that have been measured) is that it has some fairly high distortion. In this case there appears to be a giant peak at ~1300 Hz as shown in Dickason's review linked below. I realize most of this is 2nd order harmonic (up to 4%), but the 3rd order also clears 1% in this range, which from my understanding should be clearly audible. Is the problem that other drivers are not better here? (Wondering about the SB Acoustics SB15CRC30-4, where the IMD has been measured but I can't find harmonic distortion tests) Or is it that the strong 2nd order harmonics are inoffensive enough and mask the 3rd order for most listeners?

https://audioxpress.com/article/test-bench-faital-pro-6rs140-midwoofer-midrange

Hello , cheer up Dayton Audio for this DIY gem :

https://cdn.xingosoftware.com/audioxpress/images/fetch/dpr_2.25,w_300,h_394,c_fit/https://audioxpress.com/assets/upload/images/1/20240228205005_20240228180745-VC-Cover202403--March1.jpg

Measurements by Vance Dickason are way better than expected , the Sig180-4 show no weaknesses!

Am I dreaming ... or some good soul alien must have beamed me into wonderland 🙂

But wait until the Sig120-4 will be klippelized , I guess some other designers will burst into tears seeing the meas' results!

Future is golden! (in our little DIY universe)

At the moment I'm using a B&C DE250 on an RCF H100 horn from 3,5kHz on up on my open baffle setup.
I also have some Air Motion Transformers and some Dipole planars I frequently put on them.

Out of the three options the B&C RCF combo has by far the best dynamics which also improves the bass of the system quite a bit (yes, no typo)
However, the other two options sound more natural, they have better top-end resolution and have a different presentation which is a bit more relaxed. It is not that the The B&C RCF combo sound aggressive or too forward, it's more the lack of top-end resolution that makes most of the difference. Since this is already a four-way system I don't want tot turn it into a five-way system by adding another super-tweeter. Besides, in my experience with super-tweeters in the past is that they add something nice but have a trade-off in image stability.

The option I'm currently looking at is to either try the Faital Pro STH-100 with the Faital PRO HF10AK or HF108R or go for a better dipole tweeter like a Mundorf AMT, both math the off-axis response of my wideband midrange pretty good.
I have tried the big ESS AMT's but the magnet structure forms a pretty bad-sounding waveguide and I have never been able to integrate them into the system properly.

Has anyone compared the B&C DE250 in either RCF-H100 or Faital STH-100 to the Faital HF10AK or HF108R? Both Faital drivers might have a better top-end resolution in theory but I would like an opinion from first hand. I have read the HF10AK is supposed to have more "air" but I wonder if this is really more resolution or just the rising frequency response. Frequency response shaping is also easy enough on the DE250 but that does not improve its resolution. I'm not much interested in the response towards the lower end since I cross them at 3,5kHz and won't go any lower anyway. Most of the discussions about compression drivers seem to be about how comfortably low they can go, I'm more interested in how comfortably high they can go.


Anyone?

I've always been captivated by the power of music. As a child, I would spend hours tinkering with my father's old stereo system, trying to understand the magic behind the sound. This curiosity eventually led me to pursue a degree in Electronics Engineering, and now, I'm excited to explore the world of Audio Engineering.

I am interested to built a circuit i notice at http://webook.fset.de/20091999PHCHO/audio/prepre.htm
inside the author recommended to use the transistor recomended to him by toshiba
the transistor is TBC559
is this transistor similar to bc559 made by philips/motorola
i am wondering as tbc559 can't be sourced from where i am staying(M'sia)
any other transistor type that can be used ?

Sold

Have two sets of Miro PCM1704 DAC boards for sale.
I will only get either board sold, and I will keep the one not sold.
Please read the condition of the board stated below, and note the individual price.

What you need to provide :
1. You will need to give it PSU with rails +/-5V (Analog) and +/-5V (Digital).
2. i2s source (Amanero Combo384 USB-i2s, JLSounds i2soverUSB are some examples) is needed to feed it in order to play music.
3. Two pieces of single op amps or whatever IV stages you have.
4. Chassis, wires, connectors etc

Board fully populated with good quality caps eg. Elna Tonerex, Nichicon KZ, Vishay mkp and Kemet mkp film caps, Panasonic acrylic caps, Samsung ceramic caps. all the signal resistors are low noise non-magnetic resistors with copper leads, good quality Nextron IC gold plated contacts sockets. Packed with high quality components. As seen in the pictures, both boards have different types/brands of components. Both boards also have u.fl connectors installed in case you would use them.

Payment by PAYPAL FF please.
I have sent 50+ packages to US, EU and a couple to Asia. All receive the packages in good condition.

I’ve been experimenting connecting the outputs of Nakamichi EC-200 electronic crossover in different way by tying low and high frequencies outputs together via Y-cables. The objective is to use it as a bass boosting that is splitting low and high frequencies apart for allowing level adjustments independently and merging them again before sending it to a single amplifier, see attached. The unit was inserted at tape minitor loop of the preamplifier section of the integrated amplifier. Normally, the high frequency level will be left at fully clockwise (maximum position). And the low frequency level will be used alternately from min to max positions for adjusting bass level. After experimenting, I found an issue that the signal cancelled (output decreased) against each other when the low level knob was set at fully clockwise (max) and fully anti-clockwise (min). But it summed at around mid-rotation. I’d like to ask if there’s a potential to modify the unit to completely perform as desired description earlier.