Need a wee heater for my Feeders. saw something where 4 ...100 Ohm 1/4 watt resistors ( parallel) epoxied to underside of feeder provided 1 watt heat off of a cheap /ubiquitous USB power wart.
What resistor assembly could produce say 1.5 to 2 watts on a 5 v 1 amp or even 12 V 1 amp wall wart ? Have a few unused ones on hand
Hey.. this is what old guys fixate on.. apologies.. if not strictly Audio.

Available 6 (stereo) pcbs of the Prasi/XRK FH9VX amplifier board.

£3 each posted UK
£6 Europe and most of ROW

Glassware ACF-2 kit with matching Edcor XPWR054-120.

New cost is approx. $187 + shipping + long Edcor waiting time.
I am asking $130 + shipping

Edcor GXPP-10-8-8K Pair (used) -- New cost: $115. Asking $30 (low price due to short leads)
Edcor XPWR152 (new) -- New cost: $64. Asking $40
Edcor CXPP25-MS-8K/23% Pair (new) -- New cost: $194. Asking $160
Hammond 370FX (like new) -- New cost: $~120-130. Asking $80

AnTek AS-1T250 (like new) -- New cost: $38. Asking $25
Hammond 159T choke (new) -- New cost: $32. Asking. $20

Shipping not included

Hi DIYers,

I’m looking for a replacement for the NEC 2SA539 PNP channel transistor, TO-92 package. The pinout of a replacement won’t matter, I can bend legs. The KSA539 is unavailable, much like the original.

The original specs are as follows:

Maximum Ratings:
Collector to Base Voltage (V CBO) -60V
Emitter to Base Voltage (V EBO) -5V
Collector Current -200mA
Dissipation 250mW

Characteristics (at conditions: V CE -1V, IE -50mA)
Current gain hFE 80
fT 200Hz
Cob 8.5pF
hie 20 Ohms
Collector Cutoff Current I CBO, max 0.2uA, V CB -30V

Brand new reproduction of original cage.

Painted black. Great for shipping / storage / protecting little hands and pets.

$109 + delivery

Jono

Hello!

So, I’m in the East Midlands studying a Comp SCI course which involves some soldering (pi based projects) and of course, diyaudio. Can you guys recommend any cheap soldering station like in Aliexpress?
Do I have to go with weller or hyko for some basics stuff?
Budget £50 btw

Thank you so much!

I have a pair of 4 ohm Wavecor 8”( http://wavecor.com/WF223BD01_02_specifications.pdf) and wondered what would be a good choice of a dome tweeter to go with in a 21-26L sealed box? Is there anyone that would be willing to help with a crossover design that will get me in the ballpark, I will happily compensate. I don’t as of yet have measuring tools but plan on purchasing soon.

Hi I am hearing unusual whining/mechanica/airy noise from left channel and only in my room.

I tried the amp different room no noise, also I moved the amp the noise increase/decrease.

why is it only in my room? How can I eliminate this noise?

Hi,

I have a Cavalli LC which recently stopped playing music. There is a pulsating sound coming out of the headphones which sounds like a slow motion helicopter in the distance.
There are two push buttons on the front of the amp. One for choosing balanced or SE input, and one for 1x or 3x gain. When I push any of those, the frequency of the pulse is doubling.
You think I have any chance of fixing this with only a soldering station and a multimeter?

If so, where would you start searching for fault?

Best

Theo

Looking for an Assemblage DAC 2.7 standard or upgrade in very nice condition.

Please PM me.

Hi, everyone

I just bought a pre-owned Cavalli Liquid Carbon (V1 not massdrop) from Head-fi

The first day is fine, but in the second day when I turned it on I found my LC have some problems with the volume; btw I used 6.3 jack, the sound from left channel is super large, like turn the volume to 10-12 o'clock and I can not adjust it
After couple mins, the sound from left channel became lower, but still when I turn the volume all the way down to minimum I still can hear some sound from the left channel.

Anyone had this problem and replaced it themselves? Or any recommendation for fixing it?

Thank you guys
Ryan

very informative site!

Greetings!

About a year ago a fellow here helped me to make this crapy amplifier, which works suprisingly well.
I dug up the schematic the other day and i keep on wondering what kind of VAS is this?
I do not understang this configuration, or how it functions so i will kindly ask if someone has some spare time,
to explain to me what the hell is this config. I read Bob Cordel s book but its not in there.

I'm having this very odd issue with some speakers I built. They are a high efficiency two way design consisting of a Selenium WPU1507 woofer and a Selenium DT220I horn driver on a rectangular wave guide in vented cabinets. The crossover point is set at roughly 2.5k with 2nd order LR filters. Tuning frequency of the enclosure is 40hz.

The issue I'm having is I'm getting a buzzing type of distortion from the woofer itself at frequencies near and in between the two resonance peaks. The level of distortion gets worse as you increase the input level and remains proportional to the overall output level of the audio signal I'm driving it with. It sort of sounds like the voice coil is rubbing, but the woofer itself is mechanically ok without any hint of mechanical coil rubbing when pushing on the cone by hand straight and even at any angle of the cone. I also tried pushing on all areas of the surround, spider and as well as checking the coil input leads for vibration. I did this at the back side of the woofer too by sticking my hand through one of the ports. I bypassed the crossover completely with no change. The cabinet has absolutely no air leaks anywhere (except through the ports). I tried different amplifiers and test signal sources as well as music. When I pull the woofer out and test it free air, it doesn't do this. The distortion is coming directly from the woofer cone. The other speaker (woofer) exhibits the exact same symptoms. I checked the impedance curve of the woofer in the cabinet and saw no sharp little peaks or resonances aside from the two basic resonances around the enclosure tuning. Outside of the box tuning resonance area it plays very clean. I just don't get it!

I'm starting to think this has something to do with the motor design of the woofer, specifically regarding some sort of electrical non linearity caused by fluctuating coil inductance. I don't have another lf driver to try and honestly I wanted to stick with these woofers because they sound so clean and open in the midrange with their fiberglass cone. They transition very well to the hf drivers, not to mention they play fairly low with nice lf detail. It's just this distortion that's annoying and for the life of me I can't figure out the cause.

Anyone have any suggestions?

Hello from the New Forest in the United Kingdom.

I've not built a sub before ( or any speaker for that matter ), so please be gentle. I can however build houses, so I do have some level of intelligence. I am converting a garage into a movie room and I'm looking at buying some second hand ( but working and in A1 condition ) JBL 2242HPL drivers.

These drivers are in :-

https://jblpro.com/products/4645c
I'm looking at getting two of these JBL 2242HPL drivers to make two Subs. These subs will sit behind a AT screen between my LCR speakers.

The LCR set of speakers are :-

https://jblpro.com/products/3677
L Sub C Sub R

As the LCR speakers are only 292mm deep I will not really want the sub to be more than this. Is it the case I need to ensure the enclosure is the same volume as the 4645c, with a hole of the same size ( port ) in it.

The 4645C shows an internal volume of 225ltrs ( 8 cubic feet )

1010mm high x 674mm wide x 450mm deep ( not taking into account thickness of materials used )
966mm x 630mm x 386mm ( taking into account materials used ) = 234Ltrs

So, if I built something that was ( internal ) :-

1600mm x 566mm x 256mm deep

This would then sit between studs that were 600mm wide and the sub would be 300mm deep ( based upon 22mm thick material for making it. I would put a port hole the same size as used in the 4645c.

I would put bracing inside too.

I am sure it is more complicated that what I have just mentioned, but any comments would be appreciated. Please don't be toooooo technical with me 🙂

NOTE: I have a new JBL 4645C but it won't fit ( nicely ) behind my AT screen. Thinking about it. It might not be a bad idea to just buy another and stick them both at the back of the room symmetrically. That would save an awful lot of hassle ! It's not too much more than buying 2 x drivers + time + materials !

Hey guys!

So i finished making my K-402 MEH in wood and brought them in a large room.

There is only A TV desk, speakers, a sofa and that's it.

This is how the room currently look like:



The RT60 times a very huge:



Since this a huge horn with directivity control down to 100Hz, i figured i don't really need much of 'first reflection' treatments. What i need is to treat walls near the edges of the horn and somehow reduce the reverberation time of the room.

I will be placing QRD diffusers on the ceiling covering 3 meters between listening position. To cover half of the space i will need about 13 of them.

This will be made out of high density XPS, painted and look like this:



Will place a rug on the floor between the sofa and listening position.

And on the side walls near the sofa i am thinking of placing Leanfractal diffusers. 3 pieces on each side wall.

Leanfractals on the front and side walls will look like this:



Oh, and 5 diffusers on the back wall with some furniture:



Will it be enough to deal with excessive reverberation? Or do i need more absorption rather then diffusion?

No fault of my own incompetence of amp building here. I have a huge amp. And it’s ******* New Year’s Eve!!!! It’s time for 7 year old disco party. I uncorked the amp (flat amp x3??? =louder) and bang, 1700 (time of day) dead big amp.

quick headlamp amp swamp to stand by class D (?) Akitika GT-102 and we’re back to New Years karaoke.

ya know how James Webb Space Telescope has a few “single point failures” well, my Pass F5T has about 16 single point failures, and one of them cooked. Heh heh

more stories from the trenches!!!

happy new year.

Hi, Gang,

I am trying to repair an AR amp that someone else started, the PS has been taken out already. I have the SM and update notices. I expected the 2 ~16 ga purple wires to be +/- 39V to the drivers & outputs. But when I visually trace the wires, and ohm them out, neither go to the collectors of Q19, Q20, Q23, & Q24. Nothing else looks likely. This should be trivial and I'm stumped - what are the 2 purple leads, please?

Thanks,
Frank

https://flic.kr/p/2mesNsZ


https://flic.kr/p/2mesN5E vkmusic

TUBE SET 1 : Mullard CV4024, Mullard CV4003 + WE300B
TUBE SET 2 : Mullard CV4024, MUllard CV4003 + COSSOR/LINLAI WE300B

18W X 2 ---> P1616D is powerful enough to drive a lot of speakers
For the Output Transfomer options, you can pick stock Japanses OPT or HASHIMOTO OPT...

Please stay tuned for coming project..

A few years ago I introduced a Danish friend to the beauty of single full range drivers. He contacted me a few days ago, after hearing what I believe must have been the Beauhorn Virtuoso, and asked me to construct a top of the range Lowther design for him. He's quite a peculiair fellow, an investment banker of seemingly unlimited means, who sets his mind on things then subsequently sticks to it; forever! I say this to pre-empt the obligatory "why don't you try a subwoofer" and "how about a 4-way, Open Baffle etc. design” replies. I've had these - and more (Feastrex, AER?) - discussions with him; he wants a top of the line -single driver - no subwoofer - no OB - money no object - Lowther design.

I suppose this means he would like a design utilizing the Alnico range, DX4 or EX4. The size of the design is not relevant. The room in which he will set them up is the size of a two car garage. Despite the size, the room is acoustically fairly dead, with many soft furnishings. The speakers will be driven by a KT88 SE I built for him quite a while ago. His current set-up includes this amp and a pair of Klipsch loudspeakers. He has no real corners to "corner-load". He can easily move the speakers away from the wall if necessary.

As for myself, I have no objections against filters, if used to even out the frequency response, baffle compensation, notch etc. I realize that every design will have its compromises. What I believe is important with Lowthers is that if a filter is involved it's calibrated towards a driver that has 200 - 300 hrs of playtime. Because he wants no additional LF assistance the design will need to generate bass sufficient for Jazz, Folk, Country, as well as world fusion Buddha Bar like music.

What I need to be successful is to have a tried and tested design, filter and all if applicable, preferably a good set of plans so I can have a carpenter do the initial cutting of the panels to save time. For any necessary or suggested tweaks I'd involve the diyAudio community.

I'd probably order the units from Lowther-America in May or so and build the speakers in August. I need advance time for the carpenter (he's great, excellent, but always busy and always a "man down" it would seem). If there is interest in the "community" I wouldn't mind sharing photos of the build and/or trying different techniques, set-ups etc. together.

Finally... my suggestion would have been to "buy a Beauhorn" but then, why should they have all the fun...

Ron

4700mF 35V Nichicon KG Gold Tune
I have for sale n.22 4700mF 35V Nichicon KG Gold Tune caps. They have been in an amp never finished so they are practically unused.
Asked 22euro + shipping

I was looking for a nice electronics and audio forum to join.

Just started my reg here because I lost my previous account where i was only looking through the treads rather than posting.

Cheers!

​

Hello All
I am looking to purchase a RTX6001 analyzer within US.


Thank you!

Hi!

My HP8903A has a fault on the A6 board (amps / attenuators from oscillator to output) and the version of the board is not covered in any of the various manuals I have available. The serial prefix is 2414A and the board is 08903-60105. I think it's a stepping stone to the 8903B. It has 3 relays on it (not 2 or 4!) but the gain balance looks wrong (to get correct output level from instrument the oscillator level is very low).

I have manuals for 1942A /2006A and 2450A to 2948A for 8903B.

Does an intermediate manual exist or will it be photocopied revision sheets. I think Artek may have one with the revision sheets but this doesn't look fun....

Alan

After my Denon PMA-560 output relay tripping thread, diyaudio user Karl vd Berg asked for a scan of the service manual.


I thought I'd do that and put it on a "PMA-560 fan site": Denon PMA-560 fan site 🙂


Karl did a major overhaul of his PMA-560, which is documented here: Denon PMA-560 Restoration / Refurb / Recap / Rejuvenation / Overhaul


Feedback/comments welcome

Selling

One pair of One Electron UBT-2 OPTs, used (wires have different lengths) : 125€/pair
4800ohm to 4-8-16 ohm / max prim dc : 110ma

One pair of Sowter 8424 Interstage transformers, used : 170€/pair
20k series/5k parallel

All prices excl worldwide shipping

Thought I might start what might be an interesting thread:


Just a single photo of what's on your work bench today ?


(You can guess what it is if you want but post a photo of the product you're repairing too)



I'll start you off with this:
(Not my usual vintage but someone's gotta do it 😛😉)

Hi Guys,
Came across this : www.nataudio.com/products/vacuum-integrated-tube-amplifier/item/29-single-hps.html.

Wonder how they attain 50 watt using just 1 Gm70, is it possible ?

Thought I’d turn to the pros to help with a speaker problem I’m having.

My speakers have developed an issue that kinda sucks. Up to this point I’ve not had any issues, but they have suddenly developed some sort of resonance centered at 100hz. The way the speakers are constructed, there is a false baffle with a slight horn flare. I’ve tried isolating the baffle and it’s still there. If I damp the rubber surround with my finger I can damp the vibration, so I’m pretty sure it’s in the driver (which I believe are Peerless). My first instinct was a loose screw in the driver mount. Unfortunately, there doesn’t appear to be any way paat the baffle without major surgery. The only other possible thing is one of the binding posts got loose so I did the pull and twist move to resecure it (nut is inaccessible), possible twisting the internal wiring (though I tried not too). The resonance did start appearing (at least at this level) after the fiddling with the binding post. Side note, I also tested with the port plugged, no difference. Anyone have anything similar happen? Suggestions for diagnosing before resorting to desperate surgery? Speakers are Be One Audio The Three. Small company based in Thailand now defunct with no known way to contact. Any ideas appreciated.

I have a video of the resonance but can’t upload here. Can put online somewhere if it would help.

Does anybody know how I can find a replacement for these? I've looked around but can't seem to find anything. No datasheets or anything. Kinda lost, could really use a little help if anyone has any info on these. Thanks you in advance

Hello i have a pioneer Sa8500mk2 and I got it as a defect unit and the Volume switch was out of it so I tried to find a replacement one, but i could not but i did find one with the same specs smaller but blue but I am a bit lost on how to wire it up? does anyone have a photo of the switch wired in the unit close so I can see the wires ?? here is the link to a replacement switch ... would the wiring be the same?

https://www.conradelektronik.dk/p/a...es&utm_source=google&utm_term=442771&vat=true

This amp had a pretty major power supply failure. It came to me from what appears to be a tech that gave up on it. Has new PS drivers and transistors, new output transistors and the output driver card appears to have had u1 and u2 replaced.

I am at a loss and hope to get direction. Currently I have the rectifiers removed and the amp powers up in protect. Here are the voltages I have on the TL494. Am I correct in believing pin 16 is high?

1. 0.015
2. 4.870
3. 4.697
4. 4.929
5. 1.481
6. 3.652
7. 0.011
8. 13.17
9. 0.011
10. 0.011
11. 13.17
12. 13.17
13. 4.961
14. 4.961
15. 4.961
16. 6.82

So for a while I had a set of ‘78 Klipsch lascalas that I truly enjoyed the sound of. The mid bass hump, while not flat, was nice to listen to and I very much dig the love or hate “horn sound”.

Only issue was I wasn’t in love with the 12 cubic foot black boxes in my listening room and wanted something a little nicer to look at and also that was in two pieces like the modern LaScala to make them a bit more manageable. I’d heard people have had great results with the K510 horn from the Jubilee so decided to go with that. (The 402 is just too huge to consider for me).

So CAD was thrown together based on LaScala plans and measuring the set I had, parts were ordered and things have started to arrive so I figured I would document the process here. Here’s a quick list of what the project consists of.

• 1” Russian birch for the outer panels to calm the resonances I noticed in the originals using 3/4.
• Eminence Kappa 15C woofers for the bass bins.
• Klipsch K510 horn clone (thanks eBay)
• JBL 2446h compression drivers (was going to go b&c but found a good deal on these second hand so giving them a shot first)
• Minidsp for the EQ for the CD horn and crossover
• Two piece construction so if I for some reason hate it I can just build a top half with my Altec 511b’s and some CT120’s, use my ALK passive crossover and abandon active/two way (unlikely, but peace of mind is nice)

I’m open to suggestions for setting up the active crossover, I don’t have a ton of experience besides some basic room correction. I do have the umik-1 and minidsp 2x4. Oh and for amplification it will be a Bryston 4B for the low end and a 2B for the highs.

First post doesn’t have a ton of progress yet, I’m currently waiting on the horns, compression drivers and plywood. That said, I have the woofers and the motorboard and wings are being made from MDF as they’re not seen so that was started yesterday.

Does anyone know how it access all/any if the past messages, or have they been deleted?

Hi folks


I need to build a PSU for the pair of ACA boards I have, which I intend to use to make a pair of monoblocs.


So I was looking at the diyAudio PSU board v3, but building it as a point to point version.

This is the original schematic minus the rectifier section as I plan to just use a monolithic rectifier as I already have several of those.




For powering an ACA board, I believe I can simplify that to this:




To build it point to point in the way I was envisaging, can I do it like this?




C1-C8 would be Dubilier 6700uF 35v caps I already have, but I'm not clear on what values for the other parts, assuming I want a 24V output.

I was told these are step up transformers. Marked Thermador Geo Trans TG-310.

Are they useful for audio?

looking to swap exicon 10n20 / 10p20 for hitachi-renesas 2sk1058 / 2sj162 in the UK


the exicon 10n20 / 10p20 parts have not been soldered but have been used via screw terminals

Hey all. I completed a TSE-II build with 45s a few weeks back, all went great, checked out perfectly and sounded beautiful on my test bench.

I rehoused it this weekend into its newly built case and there's a problem, the output tubes are not heating… here are my voltages:

No tubes installed:
-0.35 VDC B+
-137 VDC B-
5.4 VAC Rectifier Filament VAC (Pins 2-8)
8.26 VDC 5842 Filament (Pins 3-9)
0.48 VDC 45 Filament (Pins 1-4)

5AR4 Rectifier installed:
345 VDC B+
-137 VDC B-
0.46 VDC 45 Filament

5842s installed:
Biased to 175VDC
331 VDC B+
-137 VDC B-
5.85 VDC 5842 Filament
0.44 VDC 45 Filament

I think all checks out good except the 45 heater voltages; obviously expecting 2.5 VDC here. Resistors all check out fine. Any help greatly appreciated!

For sale mint condition Satori 5", $400 USD for the pair. Never soldered, never overdriven. Continental US only. Thanks for looking.
https://www.madisoundspeakerstore.com/approx-5-woofers/satori-5-mw13tx-4-textreme-cone-woofer-4-ohm/

good day ,

I am repairing a Cadence ZRS C1 mono car amp, i found out no signal to 1 bank of the amplifier section that is why the audio is very weak. Can you please provide the IC numbers of U2 and U3 in the picture of board driver of the mosfet in the amp. section. U1 chip is readable but U2 and U3 i believe was burnt out. Thank you in advance.

I do not know why went so unnoticed.. there is only few tweeters which can be used below 2kHz, and this one looks very usable..
https://www.monacor.com/en-us/monac...y/speaker-technology/hi-fi-tweeters/dt-350nf/

Speaking of loudspeaker, I understood their was a trade-off between : compactness of the enclosure, low cutoff frequency, and sensitivity. You can have two of those, but not three.

So I wonder, how can Klipsch makes something like that : https://www.klipsch.com/products/rp-400m-bookshelf-speaker
exterior (!) volume : 8.2Liters
low cut-off (3db) 52Hz
sensitivity : 93db @ 2.83V

I see no speaker on the shelf which can do a similar thing. (low VAS, low FS, high sensitivity)
How are they doing ?
My best hypothesis so far is that they dont, maybe the 93db is a maximum very far from 50hz (and the sensitivity is closer to 89db or something), maybe there's a bump at 55hz (and a hole deeper than -3db between 70hz~120hz).
But, are they doing it ? Can I do it too ?

Can i replace a 2n6p tube instead of 12ax7 of vibrato ?

Anyone done an entire living room ceiling with 2 or 3 inches of Owens Corning 705? How did you cover it, how did it sound?

I have just purchased a mint Linn Sondek, Ittok VII, Valhalla, Trampolin with a Grado Reference Platinum.

In 1983, I bought a new Linn LP12, removed the Valhalla board, ON/OFF switch and put them in an aluminum case. There was a slight improvement in sound. Please see scanned photo, left box.

Now, I am thinking of purchasing either the Hercules II from Stamford Audio or the Mose + Hercules board fully assembled and tested directly from Hong Kong.

How many of you are using any of those boards and how content are you with this mod?

Best regards,

Looking for tech who could build me 01A preamp based on Ale Bartola's 01A low gain design.
I have procured all PBCs already.
We could agree on all details/specs/pricing, I am very open minded. Please PM

Hello,

I bought my chips from Rochester Electronic. Never used. So totally all of Genuine. I'm from Turkey, Ankara. Please send PM for payment details.
My Best

Price;

I posted this the other day and the post disappeared. I'm looking for a 2.4µF non-polarized cap to protect a tweeter and Google isn't helping me. I suppose I could consider two 1.2µF wired in parallel?

I own many GFA-565's and a couple of 585's, and I run my theater on these amps. Since I own a fleet of them I have decided to attempt to become competent at repairing them. Am I insane, of course.

I bought a broken one on ebay for pretty cheap and it is pretty broken. I bought a new input board from Hoppe's brain but the output transistors are destroyed so I will be replacing them. The input board was recapped at some point, but I am going to replace the input board just as a matter of getting all of my amps up to a standard configuration as I go through them. I also plan to implement the various tricks I have dug up on the forums and hope to improve their sound quality a bit along the way. I am not unhappy with them, but while I have the iron out I might as well.

Do people move the DC rail fuses internal on this amp like the old 555? If so what do you suggest for fuse holders? It looks like I could save some wire length, and one of the rail fuse holders is wrecked already.

Hello everybody!🙂

My name is Oleg, I’m from Russia, Saint-Petersburg, so first of all I please you to excuse my English and also I’m new to electronics, and my question can be to lame, but I need answer anyway…

Few months ago I bought used Philips Fidelio p9 – portable bluetooth speaker. A bit later it broken and local service told me that they can’t repair it, so I decided to build same thing by myself. That’s how I found this forum🙂

So. I’m going to build a Bluetooth speaker which will use SLA 12V 7Ah battery. And the main question is under voltage and overcharge protection. I want it to be pretty simple as it was in Philips – you plug the supply jack and charging started, if battery is charged – charging process doesn't start.

Question 1:
Block diagram:

This is my diagram of battery protection and charging: «power supply - power supply jack - Automatic Battery Charger – battery - Undervoltage-lockout – amplifier». So the first question: is it logical diagram? Is it right? Will it work? How will it work if my speakers are turned on, will the battery being charged, and will it take longer to charge?

If this block diagram is correct, than I can move further. And here’s the next question:

Question 2
Battery charger and overcharging protection. As a charger, I want to use this scheme using L200C:

Resistor R2- R6 depends of the battery capacity (0.1C, so i chosen R4 - 0,75A). I want to add a relay, which is driven by transistor (I found this scheme in internet. Here it is: Simplest SMF, Automotive Battery Charger Circuit Diagram Explained | Homemade Circuit Projects ). This addition must to turn off the further charging process if the battery is fully charged. So, please , look at this scheme, is it correct, will it work?



Question 3
Also, I presume, hysteresis is needed here for this situation: let’s imagine, that we connected the power source (I mean 220V socket and power supply) to the system, the charging started, meanwhile the speakers were working. When battery became fully charged (It’s important to say that we use cycle regime, so it’s around 14.5V), the system locked off the charger, but when the voltage became not 14,5 but 14, 4999 the charging process started again. Overcharge protection would turn off and on the charger many times - jittering would happen. That's why the system must turn on charger only at level of 13,5V (as example). This is hysteresis. So the question is HOW TO ADD HYSTERESIS HERE?

Question 4
I also made some findings, please to read and agree/disagree with me:
1) Battery work in cycle regime. Not in storage regime.
2) The cycle regime charging voltage - 14.5V
3) As soon as battery charged it must be locked off the load!
4) As a result of item 3, we need hysteresis

I’m sorry for mass of text, I was trying to write it shorter, but…) I also read a lot from boominator threads but still need to get information. I can’t use some turnkey solutions because of the cost. I hope answers would help other boombox makers)))

So i had a 909 serviced a while back and they changed the main caps and the transformer out, and now it doesn't sound as good lol (when i was expecting it sound better).

The sound is even more laid back and flat (not good lol).

The transformer is presumably an off the shelf of some variety and the caps are Kemet/BHC.

I figure both of these things are effecting the sound negatively, rather than it just being a single bad item.

I know Naim Audio use Talema transformers, if i asked them to make me up a transformer would it likely improve the sound?

Is it possible the Naim transformers colour the sound in a pleasant way, are are they likely to be dead quiet which may possibly be a bit boring?

No need to wax lyrical about Synergy-type horns. Lots of advantages obviously.

My question: why are midrange ports not more common on flat baffle speakers, i.e. speakers with 180-degree waveguides? The same caveats apply, such as minimizing midrange chamber volume, avoiding internal resonance and phase cancellation, etc. But I could see various situations where the use of port-fired mids would significantly reduce c-c distance to the tweeter, compared to conventionally-exposed direct-firing mids.

Of course, one big downside: midrange drivers are often physically delayed vs the tweeter right from the get go, so you're almost forced to use DSP to correct the time delay if hiding the mids behind the baffle... besides that and additional cost/complexity, what else? You can fit larger, more sensitive, higher power-handling, lower distortion drivers for the same c-c distance, generally speaking, not to mention achieving c-c distance that would otherwise be impossible.

Do you know any drop-in replacement for the quad CMOS switch Toshiba TC9145P (similar to 4066 but 16-pin)?
Also trying to find a spec sheet, but seems to be unobtanium...(yes, I have checked alldatasheets.com)

Hi enjoying the posts on the forum, have been searching possible mods for my dacmagic have completed a suggested mod on headfi which seemed to work quite well by bypassing and bridging caps inside dacmagic.
This is about my comfort level and quite easy to do, the mod is shown herehttp://www.head-fi.org/t/430326/cambridge-dacmagic-anyone-thread-ii/495
Unfortunately cant read schematics, I only understand on a very , very basic level.
I was looking into the possibility of replacing opamps which the dacmagic seems to have six.
I have read about the upgrade to 4 x LM4562MA with the remaining two upgrading to burson opamps.
Firstly do you consider this to be a worthwhile upgrade?
Secondly should I be considering other upgrades? Capacitors and such.
If anyone has done this with a dacmagic please supply a list of capacitors values etc.
To be honest the level of soldering required looks quite daunting and I may use someone else with more expertise than me.
All I'm looking for at the moment is advice on the possible sonic results and obviously because of my absolute inability to tell one end of a circuit board from another that the attached file is correct in assuming the positions of the opamps.😱

Hi all,
Been here (this forum) before when I need a more Pro "take" on things.
Need a project for these middle-aged hands & eyes as a good stress relief project. It's been a while but I'm a moderate skill level. So, which of these two would one prefer? Looking for personal experience, or comments on design pluses or minuses of each.
*BOOZEHOUND: J Fet design, Russian NOS oil/ paper caps.

* ELLIOT P06: Dual Op-Amp design.

The Boozehound is $79, including PCB and all parts, no P.S., Case, connectors, etc.

The Elliot P06: $30 shipped for PCB Only (w/ instruction)

Thanks for any input at all.
-Gary

From this thread covering my (attempted) repair of an old CS-800,
https://www.diyaudio.com/community/threads/replacement-peavey-cs-800-power-transistors.379993/I found a pair of NOS Motorolas that matched the same part number (as can be seen at the end of my original post). I changed the output board's speaker protection triac (it had shorted the output due to a previous DC offset on the speaker out). I fired the amp up and could hear that the channel was now working for a second... BUT there was 1.5VDC on the speaker at idle (no music playing). Within a few seconds, the triac shorted and the lights dimmed. I now have the same state as I found the amp in (measuring shorts at the output transistors).

So the problem... why could I be seeing 1.5VDC across the speaker at idle? Would this take out the speaker protection triac? I'm guessing even this 1.5VDC being shorted would be enough to kill the output transistor(s) that failed? There was no audio being played when all this happened... Just idling.

Dear All,

I have recently purchased a pair of kef Concerto, I know they are ok but lack detail. The reason I bought them is to extract the units from the cabinets and make, with new crossovers a pair of descent speakers akin to Cambridge R50 or similar. I am struggling to find any plans for a decent build. I have some woodwork skills and a bench saw and so can make most things. The crossovers are apparently easy to obtain from Falcon, but it is the use of a super tweeter and smooth out the bass etc that is my main concern. I also have a pair of dual concentric Goodman's 15" that I could utilise in a design akin to the Kef 105 if that would make more sense. That is to say use the Goodman's as a pure Bass unit isolated from the mid and treble in separate pods.

Comments appreciated and thank you in advance.

Ray

Hi.
I am an owner of a greek made pair of floorstanders. Each speaker has two Vifa P17WJ-00-08 midwoofers and one D25TG-35-06 tweeter in MTM configuration. The crossover is 2nd order L/R (electrical) at about 2400Hz. The cabin is thin and tall. The speakers serve me for 30 years, usually in low and medium SPLs.

The problem is that the surrounds of the vifas became stiff. When i press a surround gently it needs many seconds to regain it's shape.
So i am thinking of replacing them. The spec sheet of the vifas refers "high dumping rubber surround". I do not know if the rubber is styrene-butadiene (SBR), nitrile- butadiene (NBR) or butyl rubber or something else.

To your experience which type of rubber is best suited to offer high dumping?
High dumping surround is similar to low loss surround described at some online stores that sell refoam kits?
Will it be necessary to replace the spiders too after so many years of use? Visually they look fine.

I've been wanting to design and simulate a few circuits using the BF862 JFET, and I decided I had better use LTSPICE models that I truly believe in. So I measured some transistors myself and fitted the LTSPICE JFET model parameters myself.

I've chosen to take a Worst Case Analysis approach: I measured 100 BF862 transistors, purchased on 3 different dates from 2 different distros (Mouser, DigiKey) and found the two Worst Case devices: the "slowest" BF862, and the "fastest" BF862 in my collection. Then I fitted LTSPICE models to each of these FETs. I figure if my circuit designs work well with the Worst Case transistors, those designs ought to also work well with Typical transistors that fall somewhere between the fastest and the slowest devices I fitted.

(This design approach is called Vertex Analysis when performing design-for-yield optimization; you can read more about it in Spence and Soin's book. It's the approach used to design MOS integrated circuits at Intel, ST Micro, and all of the Silicon Valley startups I ever worked for. Make it work in the worst case: presto it works everywhere else too.)

Figure 1 below shows my measurements of the two worst case BF862s I found. The "fastest" (highest current) one is plotted in red; her IDSS is about 21mA. The "slowest" transistor (lowest current) is plotted in blue; her IDSS is about 10mA. NXP's BF862 datasheet says that min_IDSS is 10mA and max_IDSS is 20mA so these measurements are at the outer limits of datasheet approval. Figure 2 shows the LTSPICE simulation results using my fitted models: green for the fastest, red for the slowest. Agreement with measurement (Fig. 1) is pretty good. The simulation circuit is shown in Figure 3.

And here are my fitted model parameter sets:
The goodness-of-fit plots are Figures 4 and 5. I've overlaid the measurement data (dots) with the LTSPICE simulation results (lines). You can see that my curve tracer's channel-2 has a 38mV offset: when I tell it to output -200mV, it actually puts out -162mV. So that's why the VGS numbers at the far right edge of the plot are so goofy-looking. They're offset 38mV from my utterly non goofy steps of 0, -0.1, -0.2, -0.3, -0.4, et cetera. Annoying but not fatal, especially since we're trying to get Worst Case models and not Perfect Fit models.

Figures 6 and 7 show the measured data for the gate-to-source junction diodes. {Remember, these are JFETs with PN diodes, not oxide insulators, on the gate}

If the DIYA posting software lets me, I'm also trying to attach Figures 8-10. These are the simulated I-V curves for the fastest and slowest transistors, plus the simulation circuit. Notice the annoying but nonfatal 38mV offset in the simulation control statement.

Please feel free to use, redistribute, design commercial products with, and/or sell these LTSPICE models. They're completely free with no strings attached. However, at that price, you don't get any technical support either. Here they are; there is no more.

Mark Johnson

Like every year, I renewed my One time/year 10$ subscription to support these great forums.
Strangely I received the wrong update receipt for Fanatic One Off 2 Months, which is not what I wanted nor clicked for.
Could someone explain what happened?
Cheers,

Jacques

Hi,

I have a couple of 3e Audio ADAU1701 DSP, that I like a lot, but It only have 2 inputs and 4 outputs.

The thing is this boards also have I2S inputs and outputs.

My question is... is there any possibility to use simultaneously both the analog inputs and I2S inputs, and analog outputs and I2S outpus for a total of 4 inputs 8 outputs?

What hardware do I need? Any cons of doing this?

Also, I have an Aliexpress ADAU1452 with the AD1938 codec, which is a 4x8 DSP, and I've read in the manual that I can use extra codec boards for more inputs and outputs... is this really possible? do I just buy extra codec board, wire it and I am ready to program it with SIGMA STUDIO?

Looking for your help!

What's up?

I bought these tubes a few years ago as NOS. They were clear at the time. They were then used in an asymmetrical circuit (one side higher current than the other) and now there is a resulting flash spot on the glass, one larger than the other. Clearly this is a product of convection, but in a vacuum there is no such thing. Am I right to assume there isn't a very hard vacuum in these?

Is it heater or cathode material I wonder?

They work perfectly fine for all intents and purposes (not tested in a tester, just in the circuit where they work with nearly 600V B+). Just wondering who else has seen this before. Also, since most tubes have a top getter who would even see it?

Hi folks !

A couple of months ago I read Ian Hegglun article about current driven OPS (Linear Audio vol 13). At this time I came across an interesting Class-B amplifier modified by local member Danhard on czech forum. He also improved the old texan amp and helped me to create this output stage which main features are:

* Class-B, 150W/4R, idle current < 1mA
* Current driven output transistors
* voltage gain 1
* Positive feedback in NFB loop
* distortion < 0.01% (1-150W/4R,20-20kHz)

The following schematic diagram is not final, it was never build, maybe has serious errors, etc.
I'm publishing it for further discussion in a hope we'll able to improve it.
Ian gave me some helpful advice already, thanks. And of course the czech guru Danhard, vdaka fesak.

This is what the founder of Harbeth Speakers, Alan Shaw says.

Don't you think this is a disrespectful comment to Nelson Pass and other amp designers who have spent years on this business/hobby?

How about others who measures ACA amps or similar and find them bad according to their measurements?

This is ridiculous IMO.

Looking at the "Members -> New Profile Posts" it seems that quite a few users are confusing the Profile Post with Direct Messages. After looking a few times I see posts that some people might find slightly embarassing if they knew it was public. (I won't link it to avoid further exacerbating the problem). I guess the purpose of "Profile Posts" is equivalent to a Facebook "Wall", but it doesn't seem to be used as such, and this community doesn't really seem to be the type to do that sort of thing.

So to avoid possible confusion and future embarassment when a message you thought was private is actually public, perhaps this feature should be disabled?

The cinch sockets and the source selector rotary switch (Lorlin) as well as the potentiometer for volume control (Alps) are to be replaced by high-quality versions in a diy tube preamp device (Shindo-clone). Actually an easy task.
But because of the potentiometer, the shielding plate must have a recess, because the new one is longer in relation to the dimension of the installation depth. This requires complete dismantling, as the main boards are mounted on this plate.

The old potentiometer (model-No. ACW-136-A, black colored) looks the same than the good known RK27 series (blue colored - go to the attachments).
The new potentiometer is from NOBLE special made for Audio Note - go to
https://www.hificollective.co.uk/potentiometers/audio-note-100k-potentiometer.html
Could it be that the black ACW version from Alps, that is still installed, is a higher quality version such as the well-known blue RK27 series and in the same quality class than the mentioned one from Noble ?
If yes, I can save a lot of time.

Thanks for an advice.

i was so excited about trying out their SMT service at JLCPCB.com until i realized their component feeder fee is $3 per part, and that i would have to pay $60 or so feeder fee to get the design i wanted. I dont know how hard it is to load an smt reel into a machine but $3 per task seems exuberant to me and defeats the whole purpose of outsourcing my project to china.

Im wondering if you guys know of any other pcb company where you dont have to deal with such exuberant labor fee.

The Solid State Wiki and diyAudio Wiki Pages come up with 404 Not Found error.

hello
i'm looking for help with schematics for getting the most alternate value combinations out of capacitor switching using
- single pole on/off/on ,
-single pole on/on .
and maybe even double pole switching combinations for future projects if any one has any schematics.

I have been using 1pole 5position rotary switches for a 10n...... 100n switching though am looking for an easier way with getting the best from a single pole on/off/on or a single pole on/on, any help with a wiring schematic would be great thank you.

heres a photo of what i have been previously wiring for any one looking for interest sake.
I was also wondering when its best in circuits and what can be gained from using capacitor and coupling capacitor switching verses using resistor switching in lp /hp filtering instead. if it is all round better to use resistor switching? please excuse my lack of knowledge i am about 50% trial and error.

I got a great haul being sold on Craigslist from an storage locker owned by an old amp tech, specialty unknown. One of the gems was mounds and mounds of vintage caps of all sorts! I can readily ID most electrolytics, more common poly_______ caps such as orange drops, and obvious ones like ceramic disc, mica etc... but there are a good couple dozen types I'm unsure about. I believe many of these are paper in oil, but believe some of them might be poly_______ as well. I would greatly appreciate any help in classifying their material/construction type, as well as any insight as to which ones are more or less reliable over time.

I've grouped them in this picture based on appearance and what I already know. For example, I am reasonably sure the 4 at the bottom are paper in oil caps, and shouldn't generally be relied upon. I also believe the 3 in the bottom right are dry electrolytics, of which I am unsure of their reliability. But I am completely unsure of most of the others, especially the rectangular ones, the 4 very unique ones at the top, and the cylindrical ones towards the left, bottom left and center, which seem to make up most of the haul.

Let me know if a closer picture is needed on any of these. Thanks in advance!

Hello everyone,

I have just finished putting together an LM3886 build from Neurochrome audio. It went together great, measures fine in terms of DC offset/gain, has no static/distortion etc however I am quite skeptical on the LM3886's that I had ordered from eBay.

As they were not in stock on Mouser or DigiKey at the time of purchasing the other parts, I decided to take my chances and look for a North-American based seller with good recent feedback thus purchacing a pair for 16-17ish dollars. They came in 3 days and looked good to me, checking for any poor QC/Cloning or obvious fake markings like the use of ink or right-skewed text.

I attached an image here (I have 2, both matched pairs supposedly) :

If I wanted to build a preamp with an integrated DAC, would I need to modify that DAC circuit to omit the output stage and use the preamp output stage directly?

Just found one 🙁 of these by the side-of-the-road; They have a nice 10" woofer, seems to be fairly efficient, & a 1" dome tweeter
thought I might as well document the xover
The resistor in series with the tweeter is switchable, for -3dB it's 6.8 ohm, for +3dB it's 1.5 ohm.
The inductors are ferrite core, fairly fine gauge of wire, so I'd say highish DCR.
I'd say these are from the late 70s/early 80s
Box is 35L sealed, a layer of felt on the back wall

So splitting your signal at RCA level is supposed to leave the voltage alone...hmm...the ears disagree. That's why I run 2 matched DACs and split my signal using Toslink. I use SMSL M100 DACs to feed unchanged (maximum) voltage to my full range and subwoofer amplifiers. They're powered by mini USB connectors at 5V rated at 1.2W each. This opens up all kinds of power options from USB outlets. These DACs sound better at higher wattages, specifically the higher the better. I run the full ranger from a USB 3.0 power bank rated 18W and the subwoofer DAC runs off USB 2.0 at 10W. This combination produces the best sound, unbelievable clarity increase over the recommended power rating.

Am I killing my DACs with this over voltage situation? 😳

I've laid out a couple of PCBs from schematics I found on the Elliott Sound Products page (https://sound-au.com/) for single-sided home etching.

I've tried various Op amps from the 5532, LM4562, and OPA2134... I like the resolution of the LM4562, however, this op amp turns my circuits into a radio! I get bleeps and bloops from god knows what, probably WIFI and nearby computers, and whatever electronics my neighbors are running.

From what I have read - the LM4562 can be sensitive to things like PCB layout. Admittedly, I have never considered interference issues with much of the PCBs i've laid out until now.
I usually make it a game of trying to make the most compact layout with the least number of jumpers, I'm guessing this approach doesn't work well for super sensitive devices like the LM4562...

Would any of you be able to look at my layouts and tell me what I'm doing wrong with the output stage and phono preamp layouts below to give me such interference problems? And why the tone control circuit is somehow more quiet despite using the same op amps?

I could just use one of the other op amps... but I would like to know what the fundamental issues are.

Thanks in advance!

Is it really so that in this forum software it is impossible to have 24-hour time format?

Did some doodling the other night. Digging through the stash, I initially was after the box of 6BQ6GTB's, but I found a shoebox full of NOS 7C5 and some sockets for them. I don't need 30-40W so clearly the 7C5 is the way forward here.

Couldn't find a good operating point for the 12AT7 LTP for the phase inverter, but 12AU7 biases up nice and puts up a clean operating point. 11mA per section, op point should be OK.

12AX7 is the clear choice for input gain and tone stack gain recovery, but I still should take a second look at that and make sure it'll work the way I want. R18 is a typo, and should be a 1k grid stopper, not 100k

Borrowed from the 5F6 and some Marshall stuff for the inputs. Should work OK.