(I'm still very fresh to crossover design)

I have this Jamo crossover (ripped out of a Jamo Art speaker) and I'm really confused at why it appears that the network is entered via the negative input? 🤔

I've mapped it out and it appears that if I hook it up, the filters wouldn't sit in front of the drivers.

I'd really appreciate if someone could let me know what is happening here.

Should it be inverted when connected to an amplifier?

with apologies to the late great C&W comedian.

pretty much Wayne's design except for the use of NSVJ5908 dual JFETs throughout, and a SMT P-Channel similar to the ZVP3310. The NSVJ5908's have a 1dB noise figure and transconductance of 35mS.

It will have to run cooler than the "real" Pearl as the OnSemi JFETs have VDS limited to 15V. The 3,300uF caps are also a limiting factor.

Made the decision to keep the regulation off this board, and to use a 4-layer board.

Can anyone tell me where to find screws to fit the center cone on DX3?
I think it is a 3,5mm screw, maybe 4 mm, or something in inch?
I`ve tried to find some here in Norway, but no luck.
And it aught to be a none magnetic metal like brass.
Thanks in advance for any replies!!

Lars

Hello Community!
I was recently gifted a pair of Klipsch KSP-400 speakers that both hummed and buzzed terribly. The previous owner described one speaker as sounding like there was an angry squirrel inside. The angry squirrel was actually the usual collection of failed capacitors in the Power Amplifier Module DC supplies.

• Visual inspection showed C4 & C15 bulging slightly on both amps. No other capacitors were bulging or leaking.
• Voltage & Scope measurements at amp J16 Pins 1 & 3 revealed +/-12V supplies with huge ripple.
• Replacement of amp C3, C5, C9, C10, C4, C15, and for good measure, Control Panel PCB C14 and C15 cured the hum / squirrel noise from both speakers.
• One thing the stood out was how C3 from one amp tested open! See attached photo showing one internal terminal eaten away. This seemed like an unusually severe failure... Review of the circuit showed +/-25.2VDC on C3 and C5 that were spec'ed as 470uF @ 25V parts! TIP -> Replace amp C3 and C5 with 470uF 35V type.
• Finger temperature testing of amp U1 7812 & U2 7912 TO-220 regulators showed the 7812 was quite warm. As a precaution Digikey HS107-ND / 577202B00000G heatsinks were added to U1 & U2. A dab of RTV was added to keep the heatsinks from ever making contact with each other.
• As found Bias voltage across amp R30, R21, R33 and R36 on both amps was in the range of 4.8 - 5.6 mV.

The Service Manual does not include an amp VR101 Bias voltage adjustment procedure or spec. Can anyone in this community advise what it should be or is this an 'if it ain't broke, don't mess with it' item? Or, is there a way to determine a value from circuit topology / output transistor type? By the way, both amp heatsinks are warm to the touch when idle.

Home theatre subwoofers
Everything 80Hz and below passed to the subs, 7.2 system.

The Boss has complained that the noise from the cooling fan in the subwoofer amp is too loud [ yes it probably is] and I've just replaced the Peavey PV i 2000 with an old Kenwood power amp.
I've now got only half the power driving the subwoofers, now 250W rather than 540W per channel.
I've no idea how much peak volume I've lost if any. If it's only 3 to 6 dB or so we can live with that but if it's much more than that I'll start looking for another cheap power amp with passive cooling or very quiet fans.
I'll take the Peavey to the shed for the party system so nothing really lost

Anyone have KG CFA3, Golden Ref LV, or headphone protector boards available?

Hi,
Summer is almost here in the UK, and that means being outside is seen as a good thing by the significant other half.. cab building time 😉

I have a longer term project - a mini JCM800 tube guitar amp (still in design) that will need a small sit on cab. I'm thinking small like the old 1980s Marshall Lead12 practice amp where you can sit on whilst practicing but with a single 10" cream back and an EF80 based 2W mini JCM800 tube amp instead of the transistor based practice amp I had back in the day. Unfortunately I can't remember what happened to my old amp and so I have no references.

I have enough 12mm 9-ply baltic birch in the garage to make more than one of these, even if I doubled up the boards for thickness or used bracing internally.

The fastest way would be to base on existing plans (ie open back) I could use for dimensions - does anyone have one or two plans I could use as a base?

I have a Yamaha RX V 2090 and it goes to protect mode as soon as I on it. I do repairs for amplifiers. I checked all outputs and driver transistors and other small components on the main board and cannot find any issue. I also checked voltages on the main board according to the service manual and each stage voltages are fine. Regulators also give the correct voltages. Does anyone have any experience with this amplifier? any tip to check power supply board including octocupler and other parts. how do I make sure whether problem in the main board (amplifier) or dsp board or other area. other amplifiers I can simply disconnect the dsp board and try but this amplifier I cant find any option to do that. hence dont know where the problem is. Appreciate if anyone can help.

 Thanks

I have a Sony STR-1800 that has some moderate crackling when I adjust the volume. I assume that the pot is blown and want to replace it.

Does anyone have the wiring diagram or know the rating on the pot?

Pic of similar model (not mine)

?

This driver was damaged in an earthquake decades ago. It made an audible distorted sound only with loud piano music. The driver was replaced with a new one. It appears that some paint has been scaped off. I don't see any cracks or dents. Is it possible to repair this tweeter?

Why would any idiot want to do that you might he wondering?

This is a debate I'm having with a good friend. I have an Audio Research preamplifier, it's the main preamp in my stereo system and I love the way it sounds, and the main thing is that I have a remote control. I also have a Spectral preamp, this does not have a remote, but it does have a phenomenal phono stage in it (my AR does not have a phono preamp).

I connected the Spectral to the phono in on the audio research and turned the volume knob all the way up on the Spectral to utilize it's phono stage but still have a remote control. So... RCA from turntable to phono in on Spectral... out on Spectral (that would normally go to the amp) to Audio Research phono in (volume all the way up on Spectral).

My friend thinks by doing this I will double the output voltage and have clipping issues. My debate is that output voltage would be dictated by the phono section in the Spectral, so this will not be a problem.

For what it's worth, this seems to have worked marvelously, it sounds fantastic. I also have a Lehmann Black Cube SE phono preamp, and the Spectral does sound better.

What do you guys with more technical understanding of this than me say?

I have been rebuilding an old Pioneer SM-R150 amp from the 60's. I got it running with the old paper in oil caps replaced, and it is possible to listen to it, but there is a lot of hiss, the sound is not great, and very crackly pots indicating some DC getting to them, or major cleaning needed.
I described the amp here ...
DiyAudio - Pioneer SM-R150

I decided I do not need inputs for tape heads and crystal cartridges. In order to create something functional for today I have decided to take the 3 inputs and have Phono and two Aux. In addition to volume, it has a balance, bass and treble controls, as well as a switch for stereo/mono (both channels)/mono(one channel). I have decided I will replace the 3rd option on the stereo/mono switch with 'Direct' so the audio path can skip the balance and tone controls.

The output stage is simple (uses 6AR5 tubes, a 6K6GT in a 7-pin package) and does not need any changes. The tone stack could be better implemented as a Baxendall type stage, and I have shamelessly cloned the one from this thread:
DiyAudio - Baxendall Active Tone Control

Now I need to fianalise how the Phono stage should look. I have narrowed it down to 3 options:

1. The original Phono stage, which did not get a good rap on the thread where I discussed the amp.
2. The ValveWizard version of the classic RCA Phono stage
3. The Harman Kardon A-300 phono stage (as promoted on the AngelFire HK A-300 site, which is a source of tuition marterial for LTSpice and amp design)

I based my simulations on an '.asc' file provide by Ray Waters on this thread: DiyAudio - RCA phono preamp and reverse RIAA

The first problem is I am not 100% sure what that simulation is telling me. What is an optimum set of curves, and what is acceptable? Is that phase shift on the right axes, and what is a good metric? I will only be using the existing 12AX7 tubes with the reworked phono stage, so it just has to be good; great is for another day - I need my kitchen table back!

First up is the original Phono stage, which had switched equalisations for different sources and a 30K load resistor at the input, which I have changed to the standard 47K one. It uses an active RIAA equalisation, and to my untrained eye it does not seem to do too bad a job.




Next up is the ValeWizard version of the RCA Phono stage:



Finally the HK A300. I include it here because I have used the same approach to simulate this phono stage, and I must be doing something wrong because the curves out are very different, and I am not knowledgeable enough to deduce why. I would really appreciate some input on how to interpet this approach for analysing the RIAA equalisation.



I have included the LTSpice files, and I am using tube models from Ayumi Nakabayashi.

I've read over the years many times that no sub on the market comes close to a diy sub for the ultra low frequency. Is this still the case?
I once got given rough dimensions on a 24 x24 x48" cabinet with a 15 or 18" sub and a 1000w amp that will play happily at 18hz, and that every movie one has watched will be watched again with a proper sub.
I'm a carpenter so the build isn't an issue if I have a drawing, but if possible I'd rather buy a kit. To keep things on a shoe string budget what's out there? There was good stuff 10 years ago, there must be some nice budget builds out there now? How about a kit from Dayton audio, they say they are tuned to 20hz
This is to replace the REL strata I have.

I built a pair of the Baby Labs Lance about 5 years ago and have been very happy with them, but my room has changed and they are not "working" very well now.

These are monitors for a TV at the foot of my bed. This new bedroom has hardwood floors and the back wall is a good 6' away. the rear port on the Lance makes the sound field very wide and dispersed, not great for localizing the sound as coming from the TV.

And, I've wanted to do something new anyway. I was considering the Bloodhound before moving into this new room.

I'd like to go up a "size" on the driver from the FF85wk I'd like them to go a little lower than the Lance but bass is not a priority. They need to be bookshelf sized and the design somewhat simple.

I'm open to towers as long as they will work at the foot of a bed. I'd like to stay with a thin face plate (Pluvia 7?) so I don't have to route a recess but I can hire that out if need be.

My setup is a 2.1 Breeze Audio TP116 amp (I don't remember the exact chip but it's from about 5 years ago) and a voxel sub. No preference for the driver but prefer something that does not punish poorly recorded music and music ripped at lower bit rates. The budget is somewhat open but not unlimited. I'll keep searching the forum but wanted to throw it out for suggestions.

Excellent condition Beyma TPL150 Black face plate, sequential Serial numbers.

Excellent condition, never removed the back box, never soldered connectors, minor markings on back of one rear cover as shown, otherwise cosmetically and audibly excellent.

Will ship in original boxes and outer box. I had these in a stalled out open baffle project that was sidelined when I bought klipschorns for my main area. I haven't had to the time to revisit this project and as such they are for sale here.

Asking 700$ Shipped and insured within continental US. Willing to ship outside of this region at buyer cost.

Hi,
I am new here. I love music.
I've built lots of electronics but I've only just started doing audio stuff. I had always wanted to build a power amp, and over the weekend I just about finished it, feeling pretty accomplished with myself - though I need to add some kind of relay or speaker protection to the output, parts ordered for that, so it's about 95% finished. I hope I can gain more info on audio systems from here.

Thanks.

LTspice is giving me a -3dB of over 1MHz
all models are b.cordel and Ian Hegglun (i get the same results with other models)

with the real circuit, i measured a -3dB of around 500KHz
my 2N5xxxx are coded "B331" so i replaced these with bc559c/bc549c with the same results
mje340g/350g were replaced with old bd139/140 with the same results
(outputs are from profusion)

any ideas why the circuit -3dB is so off compared to the LTspice?

Hi. Do anyone know what kind of resistor this is?

Mvh

Hi guys, i was given a dead sony DVP-S9000ES i.e- won't turn on. I checked the fuse -not burned. There is no light, or switching on of relays to transformer of the audio boards. I am not sure where to go from here. Thanks in advance.

Quan

If anyone has a F4 (DIY or official) up for grabs in the UK let me know before I order parts. Cheers

Gavin, Oxford, UK

I have an unused 4222 evaluation board that I won't get around to using. Same board TI sells for $200. $115 shipped Priority in the continental US. See link for specs

https://www.ti.com/tool/PCM4222EVM

Motivation.

My first three-way started with my wife and one of her friends. No, really.

The friend inherited a really nice turntable from another friend's family. Micro Seiki with a nice cartridge, but the turntable speed wasn't constant. So I volunteered to try my hand at fixing it. A little disassembly, cleaning some pots, some calibration, and it was good to go.

But there was a problem. When I tested it with my stereo system, swapping out my old late 70's Technics... it was awesome. I heard things I had never heard before. Dammit, now I need a new turntable & cartridge. 🙄😆

I did that. Just purchased a Fluance with a decent Ortofon cartridge. It sounds great. BUT... the mids are a little harsh, and I can hear some nasty distortion which wasn't evident before - because the rest of the sound is so clean.

And so the next domino to fall is the speakers. Currently I've got a set of Cambridge Soundworks M80's. They're a 3 way design, but looking at the impedance plot I'm not sure it even has a crossover inside. (And the distortion - meh.)

I built a couple of sets of speakers back about 20 years ago, but have never tackled a 3-way design. But now we have decent simulation software, I've got some decent measurement hardware, the kids are gone, and I'm retired so every week is six Saturdays and a Sunday. 🙂 I've spent some time lurking here, and I think I'm ready to go. And so here's the start of my build thread!

Objectives.

• I want the best set of speakers I can afford. Of course. 😉 I want to be able to listen to Elvis Costello, John Coltrane, Patti Smith, Norah Jones. I want to be able to play the Moody Blues "I'm just a singer (in a rock and roll band)" and hear the vocals on top of the guitar and bass line, without hearing them (vocals) breaking up.
• I would also like to have a design I can tinker with, with well-behaved drivers. I love to learn, and if there's a design that I can start with, model myself, and maybe make some tweaks, now I'm learning something.
• I would like to have a design that can be adapted to a home theater setting - center speakers, satellites. Having a set of similar drivers available which can be easily "matched" is a plus. Having a set that can be dropped into existing crossover designs with a minimum of tweaking is even better.

(BTW my listening room is about 12 x 30, I'm listening across the 12' dimension. There's a hard floor I need to deal with. If the design works really well, there's an upstairs room which might also get a new set of speakers, along with a center channel.)

I was originally thinking of John Krutke's designs with his ZA14W woofer/midrange, but that appears to be NLA, at least for now. And I'm not sure how much bass I could squeeze out of that design. So, onwards, more reading.

I like Jim Holtz and Curt Campbell's designs, if for no other reason than that they're well documented. Unfortunately, so many of those designs are also NLA. I finally zeroed on on the Anthology design. It's an MTMWW design which utilizes the Dayton Audio RS225 woofer, the SB Acoustics SB15NRXC30-8 5" midrange, and the Seas 22TFF 3/4" tweeter. Some sims show that I have some hope of using this as a starting point for varied other designs, including a 2-way, a W(T/M)W center channel, or even a simpler TMW.

And so I've got my MiniDSP UMIK measuring microphone, my impedance jig, an oscilloscope (if I need it), taught myself a little bit of VituixCAD, and off we go!

Why mess with a winning combo (the Anthology design)?

Why change what works? The Anthology seems to be well regarded. But, per my points above, this project is not only about building a speaker, but about learning how to build a speaker. Jim & Curt have given enough design details on the crossover and enclosure that I think I can do some tweaking and some learning. And if I fail, I can always go back to their design!

The drivers.

The first thing I did was sim the Anthology design with the stock crossover. OK, works, except that the published design appears to have the tweeter wired out of phase; inverting the phase makes it look great. But... I've read that Jim really likes the SB15CAC woofer for midrange. I subbed the SB15CAC in for the SB15NRX2 (since the NRX is on its way out), and sims beautifully. Better than the NRX2, which has a nasty mode at around 10k that pushes its way into the overall response.

Next step - what about the tweeter? The SB Acoustics SB21RDC (or for that matter, the SB19 and/or SB26) appear to be close to drop-in into the Anthology design, with just a little tweaking, and they seem to be well regarded. An additional advantage is that there's a design for a 3D printed waveguide for these drivers, giving me even more to play around with/learn about!

For the woofer, I see no reason to vary from the Dayton Audio RS225-8.

The advantage of the mid and woofer is that there are other sizes for each which are pretty easy drop-ins for the crossover design (again, with a few tweaks). For example, one could make a pretty good W(T/M)W center channel with the SB12CAC (little sibling to the SB15) and the RS150 (again, akin to the RS225). Or, substitute the RS270 for the RS225 if I want to turn it up to 11.

The crossover.

For now, the important thing for me is that I have a starting model for a crossover and a decent simulator. The "real"/final crossover design will need to wait until I get the actual drivers in and measure them, then put them in an enclosure in the room.

I've got a simulation below. It's second order except for the HF crossover to the mid, which is first order. I've put a "dummy" L-pad in the woofer section to simulate baffle loss since I haven't figured out how to integrate that into the response curve yet. 😆 Once I get the actual drivers, I can better match baffle step with the woofer/mid crossover.



What next?

My work plan is:

• Decide on tentative design, including drivers.
  • Put that design out for the diyaudio world for comment - am I missing something? Where I am now!
• Order drivers. I hope to do this next week.
• Measure driver parameters, import into VituixCAD for crossover design.
  • Try the tweeter with a 3D printed waveguide and sim that as well - can I improve horizontal response?
• Enclosure design and build (tentative) enclosure.
• Install drivers and play with crossover design/tweaks.
• Tweak for compatibility with listening room.
• Build the "real" cabinet, with veneer and a nice finish.
• Listen and enjoy!
• Lather/rinse/repeat.

There's my project, so far. If there's anything I'm missing, or a "OMG, why the **** are you using that driver?", please feel free to chime in! (Especially before I order the drivers!)

Mike (aka Cheesehead)

Fully functional and sounds great. Used sparing. Accessories still in box. Just thinning herd to fund more purchases.

$325 / shipped?

Hi, I have electrical disturbances when I operate the motorized window shutters, the initial cue of the motors causes bad noises in the various home hi-fi systems. The general electrical panel has a dedicated line for the motorized shutters, and on that line I would like to put a capacitor/inductor that I recovered from a washing machine, could it work? Is 1-3 IN and 2-4 OUT okay? I attach image

Troubleshooting on PWM/Class-D Power Amplifier Stages - which Publications are released ?

concerning not digital amplifiers like tube and solid state single ended and push pull class A/AB there are a lot of publications available - e. g.:
https://sound-au.com/troubleshooting.htm
https://www.allaboutcircuits.com/worksheets/bjt-amplifier-troubleshooting/
https://www.google.de/books/edition...ier+Repair+service&pg=PA1&printsec=frontcover
https://www.google.de/books/edition..._Guitar_and_Amp_Mai/FCaskxpGLooC?hl=de&gbpv=0

Concerning Class-D resp. PWM power amplifier stages I just found only publications regarding the basic operation and special circuitry features, but not regarding service and maintenance/troubleshooting - go to this URL's:
https://www.soundandvision.com/content/bruno-putzeys-head-class-d
https://books.google.de/books?id=sF...=gbs_selected_pages&cad=2#v=onepage&q&f=false
https://ieeexplore.ieee.org/document/954289
https://www.allaboutcircuits.com/projects/how-to-build-a-class-d-power-amplifier/
https://www.semanticscholar.org/pap...g-Ge/e5adc785ac9fdfbd546e7bad725a6cb5fcadc341
https://www.semanticscholar.org/pap...-Wei/1b37a348f7a5418b7fe62394ce9bf28c22685b13
https://www.analog.com/en/analog-dialogue/articles/class-d-audio-amplifiers.html (go for an overview to last page)
https://forum.visaton.de/forum/mess...uben-ein-korrekturprogramm-würde-alles-regeln
https://web.archive.org/web/2020112...ion-bruno-putzeys-purifi-hypex-kii-mola-mola/
https://www.audiosciencereview.com/forum/index.php?threads/interview-with-bruno-putzey.14970/
https://www.diyaudio.com/community/...n-a-decent-book-on-class-d-amp-design.196068/ (closed thread)

what is the reason therefore ?
Maybe confidential details (B&O, Hypex and most other manufacturers always explain the same: ""No User Serviceable Parts Inside") ?

For this reason the complete class D main board resp. module is in general to replace on power amplifier devices in case if occur any failures/issues.

P.S.: why is this thread closed resp. inactive ?
https://www.diyaudio.com/community/...amplifier-books-overview-google-books.153311/

Hi guys,

I am trying to improve an amp I have here and using this nice chassis/amp as a learning platform. It's a combination of topologies I am vaguely familiar with but don't want to start smoking parts by just diving in. I have been reading about CCS in LTP, no problem by itself with AC coupling to the grids, but this amp has an SRPP (or maybe it's a CCS loaded triode) which is DC coupled to the 6SN7 grids. I have made all the required voltage/current measurements and put them on the schematic. I am planning on an LM334 for the CCS but am open to other suggestions. My main concern is the 93 volts on the tail of the cathodes and the voltage limit of 40 for the LM334. Could I put the LM334 on top of the cathode resistor, maybe drop it to 10K so the 334 has about 10V across it? I am also open to changing the input configuration to something else, maybe another LTP and AC couple it. The 2 input tubes are on a PCB so changing topologies would be a challenge, but not undoable.

Looking forward to learning more about this type of circuit.

Thanks for any help you may be able to offer.

Cheers

PS current in input stage 1.6mA, LTP ~3.5mA per leg

Coming up soon on March 5th 2023, the 60th anniversary of The tragic death of the Legendary singer Patsy Cline.
She'd be 90 years old today had she lived, passing away at 30 in that plane crash in Camden Tennesee.
What's kind of ironic is, her one popular love song, "I Fall To Pieces" struck me oddly.
Her remains were mostly intact at the crash site, except that half her face was ripped off, her body was jammed under a down tree (a result of the crash) and her one missing foot was found dangling up in a tree.
The investigators knew it was hers, it had painted toenails.
So... in a sad, tragic way, she finally did "fall to pieces".

I had the pleasure of meeting her husband Charlie, and her daughter Julie at a dedication ceremony in Winchester Va back in 2005.
Charlie is now up there with Patsy since then, and Julie is handling the Patsy Cline museum there.
RIP Patsy, you'll always have a special place in people's hearts.

Hi, I have a few original M51132FPs available, has anyone ever used this for a preamp?

Analog EQ shifts phase on boost or cut, does a EQ done in the digital domain have the same phase shift?

Hello,
I am looking for Fifopi or Allo Kali relocker 384kHz in EU.
Thanks.

Hi

I do not think I will ever make JLH Class A amp. I have some other amp on my wish list..
The PCBs are from siliconray £12 + shipping (you need two for a stereo pair, the price is for the stereo set)

Also I have some surplus Elvee's diegomj1973 denoisers single (£3) and dual rail (£4) plus shipping.

hello,

I got a surplus stock of 680nF MKP X2.

Evident uses should be capacitive power supply or generic Polypropylene circuits...

Are they typical uses of 680nF caps ?

I am ready to order parts for the above but am not sure of the DCR values for the inductors. They are not specified on the schematic. I plan to use quality air cores.
The internal wiring for the drivers is 20 gauge, rather thin I believe. These speakers are used at relatively low volume settings sometimes with my 8 wpc SET amp and sometimes with my Hegel 250 wpc ss amp.
I will use 10w wire-wound resistors because that's what is in my OEM crossover. I am considering upgrading the internal cabinet wiring to either 18 gauge or 16 gauge. My inclination would be to pick inductors with the same AWG. Of course that alters the DCR value which is why I'm asking for advice here.
Note: the OEM inductors are iron core and the wire leads look to be 20 gauge.
Opinions and suggestions please!
Many thanks, Fred

FS:

hi all, selling for a friend:

1 power transformer 28VA for different 6,3V filaments, manufacturer: AAE Transformers ( NL)​

-EI Core, grain oriented core laminations and vacuum impregnated.

PRI: 0-230V-240V ,1x screenwinding acts as a shield ( SCH)
-SEC: 6,3V 0,75A, 6,3V 1,2A, 6,3V 2,4A

finest quality, unused and never mounted.

49€

pse ask for shipping costs ( depending your country)

So i have 2 of these amps, Orion HCCA 5000.1D v1, each amp only had damaged FETs, 1st is repaired and running perfectly all new FETs, changed out all the FETs on 2nd but this amp’s Power Supply section is acting “weird” and not like my 1st. I couldn’t upload the 3 videos to here so here’s link to Imgur. My apologizes.

Login to view embedded media
3rd video shows following:
top wave chan-1: Rectifier switching
Bottom wave Chan-2: PS FET gate switching
Switching starts normally, but soon as the waves build to full the switching “degrades” into what is on video, if I remove rectifiers the Power Supply will build as in video but will stay a square wave/not degrade. My other amp does not do this, it switches correctly. But amp does reproduce input signal at speaker output terminals (when output is switching; see 2nd/3rd video)

Maybe the 2 problems are related???

1st & 2nd videos show the output switching problem possibly related to gain knob? Output section will not start switching most of the time unless gain is at/near half. I’m going to try a replacing with a 3rd gain knob, as 2nd is doing same as 1st. When amp boots with output switching proper it idles at 6.25a and reproduces input signal at subwoofer, when amp is below half or less gain output section does not start switching and will not reproduce input signal at subwoofer

As it is now the only time the amp will not work is when output section will not switch, which seems to be gain knob related, but about to try a 3rd potentiometer.

I’ve never seen a power supply switch like this and I’ve never seen a gain knob do this to output section. Really throwing me for a loop.

I scratch built a WAD Series II phono stage ages ago. I modified it with a ccs on top of the first stage and a ccs below the CF out. I really love it.

But when I turn it up, it does like to make some hum. Attached is a picture of of my iPhone showing hum at 47db when the volume is turn way up. This is very noticeable between tracks or during quiet passages, but hey I've lived with it for years. But mostly not noticeable over my wife's screams of "turn it down!"

Well, I tried something new. I unplugged the turntable leads and replaced them with RCA with 100k ohm resistor grounded as in the picture.

The hum dropped very noticeably. See the next picture at 35db.

Does this mean I'm getting noise in from my turntable?

I can't find any obviously wrong grounding practice in the preamp. (And both the phono and pre are in one box, the pre-amp stage is nice and quiet.)

Any comments would be most appreciated.

Thanks,
Dan

I've heard a number of good things about horn designs, like increasing low-frequency response on HF drivers, improvements in directivity, better efficiency, etc. But it seems to be difficult to find documentation on how to control these various parameters and how to design a waveguide with specific goals in mind.
I am planning on building a speaker with some planar drivers from parts express, but all of them seem to have a sloping FR; lower in lows, and higher in highs. Thus I am hoping waveguides would be the solution to make them flatter and easier to crossover.

I planned on just making horns using trial and error to determine some of the variables that can be used to tweak a driver's response, but there has to be someone out there who's already done that science.
Does anyone know of any design methodologies or readings to point me in the correct direction?

HI, its my first post, im a noob to the point that i am not even sure i chose the right subforum. i think the 8801 is a solid state channel strip so i hope thats fine.

I bought it used, and i love it.
but there is 1 thing i'd like to modify: you can chose 4 attack times, however for 2 of them you have to open up the unit and switch some jumpers around.
(as a sidenote im baffled that they did this in such a price range)


the Jumpers are marked in red.
So i want to switch these position without opening up the unit.
A friend who knows nothing about audio but a little bit about electronics & soldering told me i can do this easily with these 2 components:


The frontplate of the 8801 looks pretty filled up, so without looking inside the unit im pretty sure there is not enough room to somehow make this "pretty" and add it on the front.
Since its my only rack unit, and i dont even have a rack, i would be perfectly fine with having the switch hang out at the side of the panel or maybe drilling a tiny hole on top.


Im making this post in hopes that 1st of all if this is somehow a horrible idea, maybe u guys can let me know, and secondly, if it works,
there is a few questions that came to mind.

nr 1, could it be, that with jumper configurations, there is a possibility of getting 2 MORE attack times (6 total) ?
nr 2. furthermore, is there like a supereasy way to somehow add even more attack times?
dare i say a potentiometer that fluent from 0.5 ms (current lowest attack possible) up to something like 30, 50 ms ? (current max is 8ms)


im assuming the 2nd idea is way too complicated and not realistic, im just asking since it would be epic if possible.

thats it, any tips/thoughts are appreciated
thank you

Hi all, does anyone know the specifications on the Wharfedale 1040H bass driver and what model speaker it was originally fitted to? Possibly fitted to Valdus model. It is a 4 inch unit with plastic frame, Possibly made around 2001. I am asking as there is a pair for sale. Glenn

I know my chances are less than hitting a state lottery jackpot, but....
I have a pair of those cutie boxes that came with that system, but not hte rest. The problem: tohose boxes work (properly) exclusively with the matching amplifier, since they are response corrected in the low frequencies (Ace Bass system, kind of current feedback system). Without the amp the sound is very thin, not much below 70 Hz (Qts: 0.22, Fs: 75 Hz)
I reworked the woofer (removed the extra magnet, plus softened the suspension) so now they can be used with other amps too. But the crossover now is not matching, and it is potted in an epoxy box, so I can't rework that part. The sound is very good even this way, the Focal Polyglass woofer is a rather decent piece so I'd like to improve on it anyway. Does anyone has any info regarding the crossover of those boxes?

Hello good people,
Need some advice, insight, suggestions and criticism from you. I recently got onto the diy bandwagon after years of being a consumer. Two months ago I successfully built a tda 2030 amplifier 😂, and now I feel that i should join the bigger boys with a discrete AB amp.

The below is a design 'stolen' from some chinese manufacturer, it's based on c5200 A1943 outputs.
I've tested it using a 20-0-20v transformer and it was kinda working with some problems. I don't have an oscilloscope. Here in Kenya the price of an oscilloscope can feed two villages for a month. (I'm okay with that though)
So, I'm diving blindly into it with just a multimeter ,soldering iron and some poor speaker whose life is on the line.

kindly check out the attached schematics and help answer the following questions.

1. What's the best (maximum and safe) transformer voltage and amps to run it?
2. How many parallel outputs are recommend to get more power and handle 4ohm loads well? And what can be done on the drivers to make them handle more output transistors?
4. Are the biasing resistors values and diodes done well?
5. What are the improvements, corrections, that can be done to make it a better sounding yet powerful amplifier?

I'm very, veeeery new to electronics. Y'all's answers, advice and support is highly requested and appreciated

Best regards

I want to build an inductor to make a first-order low-pass filter.


I basically have to build a 5mH and two 2.7mH inductors based on which amplifier I'm going to use, but I don't know how to determine:

1. The wire length
2. The wire size (because it depends on the RMS current and the wire length)
3. Diameter and number of windings
4. Which material should I use for the core

For the high-pass filter, it was easier, from the power and resistance of the speaker I determined the maximum voltage (~35V) hence I bought 50V capacitors, but the inductor is a bit more tricky because the current is now involved and I don't know which equations I should use. Even if I did study electronic engineering, I'm able to prove the formula to determine the auto inductance, unfortunately, I have zero ideas on how to build a real inductor🤣. I would also guess that those theoretical formulas wouldn't apply here and that for sure there's some sort of simulator that can do a better job than me.

Hello everyone,
I am an undergraduate student, not related to audio. I am planning to build a sub with 2 passive radiators, I am on the look for recommendations on the subwoofer driver, as mentioned being a student, my budget for the driver is 120 dollars average. I currently have Boreas BR02's as my speakers which reach approx. 51Hz as low. I would like also recommendations, considering the driver recommended, in the box size (I don't want another bed-side table). Also considering the driver recommended, I would gladly take other ideas for ported or other, in the case it is thought to be better.
Thank you for reading.

First, I'm pretty green when it comes to chip amps, so expert help appreciated.

The amp in question is a Enlightened Audio Designs PowerMaster 500. The company is defunct, and I've not been able to locate a schematic or really much of any info about this amp, other than that it's 5 channel and uses two LM3886's per channel.

Four channels work fine, but when an 8 ohm dummy load is connected to channel five (no input signal), the current being drawn from the line goes from 800mA to about 2.5A and hangs there. Here are the voltages I can read from one of the two LM3886's for the bad channel (need to get a better needle point probe to safely reach the back pins):

Pin 1: +42.9V
Pin 2:
Pin 3: -42.8V
Pin 4:
Pin 5: +43.1V
Pin 6:
Pin 7: 0V
Pin 8:
Pin 9: -42.7V
Pin 10: -0.344V
Pin 11: -11.7V

Hi all,

received this amp in this condition, it is in protection.

can someone assist with a schematic please?

PSU has IRFP2907 & IRFP064N

Outputs are IRF640 & IRF9640

As some here may know, I've been doing measurements on acoustic guitar bodies. My preferred way is with pink noise as excitation, though I can and have done it with Swept Sine. I'm using a Dayton DAEX25FHE exciter, weighing in at about 3.5 oz. I simply rest the exciter output on the guitar's bridge/saddle and use a rubber band and clip to keep it from "walking". It doesnt take much amplitude to get a clear response spectrum; the amp I use (for the pink noise anyway) runs off a +5V USB port, with its volume setting nowhere near full.

I presented this in another forum, with spectrums before and after the application of a "Tornavoz"- guitar speak for a ducted port - invented in the late 17th century. In the spectrums, both the cavity / port and first mode of the top of the guitar resonance was evident. One astute reader challenged the validity, saying the exciter mass weighing down the top - as now part of the system - would change its resonant frequency appreciably.

Made sense to me.

Of course, the going from a plain hole to a ducted port only changes the air cavity resonance. Adding a weight to the bridge area wont change that. So the effect of the Tornavoz was valid frequency wise (it brought resonance down, as expected)

So I tried an experiment; one, where the 3.5 oz weight of the exciter was applied as a downward force; held by clip and band, the other, the guitar was held vertically as if played, with the exciter held by hand, pressed against the saddle / bridge by hand. So the exciter weight was hand held, versus guitar held.

No difference in top resonance, in fact it went slightly down being held by hand - the opposite of what one would think. How can this be?

Something to do with the compliance of the exciter at resonance makes its virtual weight go to zero - I just cant wrap my head around it. Any help with thinking this through would be appreciated! Thanks.

Hello,

Does anyone have the information for the output inductor in the DH-220? I have a unit that I am trying to restore that has been "modified", and the inductors were removed. I included a picture below of the missing part. The only info in the parts list is "L1 Output Inductor".

Hello, I have a concern over the 6L6 voltage regulator used to stabilize the output tube screen grids shown in the attached schematic. Seems like the Vhk is very excessive and, I'm not sure of the extent I can go with heater elevation. The first thing I am considering is a separate 6.3 VAC transformer for the 6L6 (I don't have a 5VAC tap on the power transformer and it is my understanding that the 6L6 CF should be run off of a separate PT winding). Should I also do the heater elevation? Any other specific recommendations? Can't say how long or how hard it was run like this. I have not run the amp much as it needs to be refurbished, but it sounds pretty good considering. I have seen one other very similar amp that Mr. Evans built that did have a separate winding for the 6L6, but this one has all the tube heaters running off the same winding. Any advice is appreciated. Cheers

Hi all, long time lurker first time poster!

After enjoying my s2000 MTMs for 4 years I am looking to build Troel Gravesen's CNO-Grande, but am having trouble sourcing a cabinet maker. I have chosen this route after difficulty sourcing quality grade plywood and also not having access to a shop this time around. I am looking for at least CNC services but also open to complete construction. I know this is not truly DIY, but I would very much appreciate any and all help 😀

thank you!

2023 - okay, I really want to go through turntable circuit of my JVC (actually Victor) JL-B31 and fix the speed problem. This is something I posted about on and off last year on another forum, but I seem to have stalled with responses there. I'm hoping that someone has the patience to tell me what to test, and in some cases exactly how, right down to "put the -ve probe on A and the +ve probe on B"...Yep; I'm afraid there are many parts of the circuit/schematic I don't properly understand. I can post photos of anything that might help to clarify things.

I have the service manual, and have spent a lot of time gazing at the schematic and the components on the boards, without much in the way of enlightenment occurring. I've done some measurements but it clearly hasn't been enough to identify the problem. A quick summary:

Powered on, the platter rotates very slowly at first, picks up speed over about half a minute, and drifts back and forth between too fast and too slow. Top panel variable resistors don't stabilize it.

The switches, power cap and rectifier diodes all seemed to check okay, though I replaced a power cap anyway. I do need to measure the TO3 transistor, and I'm unsure/nervous about what to do there: it should be 75V, measuring the collector (metal case) and...where does the other probe go?

The replaced power cap is C822, which I've circled on the schematic (along with X814, the TO3 transistor I will need to measure). The other caps in the power supply I left alone. In the end, out of a faint hope that it might make some difference, I replaced the electrolytics, as there are only about a dozen. But much as I expected, that's not where the problem is.

Any suggestions about what to look for start with this? The motor is clean and lubed and there are no obvious signs of issues originating there.

Hello,

I bought the vfet pt 3 kit, I have the necessary VFET and I want to use these parts to build a headphone amp.

What is the best way to achieve this ?

Many thanks,

Cauwil

Hey everyone! First time posting in the amp forum!

I have a Dayton KABD-4100 and the thing just hisses, I don't know how to measure it exactly but its very evident and more than I have heard in the past from other amps. I have this powered by a Meanwell Power Supply and when I unplug the input and the control board it just hisses. I have it running on a PC right now and that itself induces additional noise but just sitting there wondering what its doing with its life it just hisses.

Any recommendations on how to effectively lower the hissing on this thing?

I found some "Toshiba" 2SK389 SOIC packaged dual transistors on Ebay. They do NOT have the same pin-out as the Linear Systems LSK389.
They are marked K389BL OF
I soldered them onto some DIP adapters to test them. (I checked the adapters for correct pin translations)
The pin-out appears (and works) as:
pin2 S1 or D1
pin 3 gate 1
pin 4 D1 or S1

pin 5 S2 or D2
pin 6 gate 2
pin 7 D2 or S2

No apparent connections to pin 1 or pin 8.

The FETs trace on the curve tracer just like a 2SK170 and are well matched for gm. However the current offset ( Idss ? ) can be mis-matched by up to 25mV gate V.
(half a step division offset with 15 traces and 50 mV steps, so 25mV mis-match) One device did trace perfectly matched.
I would think that adjacent dies would be better matched on Idss. Could these be matched 2SK170 dies in an SOIC package?

Looks like these SOIC parts have surfaced before:
https://www.diyaudio.com/community/threads/help-2sk389-soic-packaged.100856/
but no resolution. No Toshiba SOIC 2SK389 apparently made.

Any way to tell which pin is Source versus Drain. They (and 2SK170) trace exactly the same way by swapping S and D around. Does it matter?

And a small detail: The SOIC to DIP adapters have a foil plane on the back side below the chip, and a big plated thru hole to a smaller foil plane just below the chip package.
I assume this is intended for some heatsinkng effect. To get good thermal contact with the chip package should this plate thru hole be solder filled or maybe just some glue fill to avoid over heating the chip. Since these surface mount things get wave soldered, it would seem that momentary solder heating should be tolerable.

I was planning to try out the 2SK389 for a Mimesis type board in place of the 2N5565 that Goldmund used. Also planning to try an Analog Devices MAT02. Those MAT02 devices DO match perfectly on the curve tracer. (TEK576) I even adjusted the beam focus to try and see any difference. Perfect match.

Greetings, I want to build a decent amplifier to drive my front main speakers. I have a multi channel 7.2 AVR that's adequate for the home theater speakers but I don't think it pushes my newest pair of speakers to anywhere near their potential and even then, it's an AVR! I was looking around online for an integrated amp for them but the cost for even mediocre quality, vintage or modern/new is just out of proportion so I have decided that I would like to take a shot at building one. All I need is a 2 channel analog stereo amplifier that I can feed with the pre-outs from the AVR and will drive a pair of speakers with the following specs; Frequency Response = 34hz to 21khz, Sensitivity = 98db, up to 150 watts RMS, 8ohms, dual 8" thermoformed crystalline polymer woofers and 1" linear travel suspension titanium diaphragm tweeter. R-800F
I have some things to possibly work with but I would greatly appreciate a list of the most basic components necessary to build a suitable amplifier for these speakers. It doesn't have to be anything fancy or even good looking, I only need it to provide decent amplification from the AVR pre-outs to the 2 speakers. I have some parts already such as a large transformer from an old Harman Kardon receiver and the base to the case it was in. I have some parts taken from different receivers and car audio mono amps and various other things around but I am not sure what will work with what or what else I will need or won't need out of what I have. So a basic list will be a good starting point for me I think and then I can go from there once I can gather what I need.

Any old punks out there? Post your favourites here:

These were late to the punk scene and soon transformed unsuccessfully into some New Romantics as I recall.

But they did leave one good punk single behind

Blitz- Someones Gonna Die Tonight from the All Out Attack EP


blitz-someones gonna die tonight - YouTube

The original pmd100 and pmd200 chips are complicated beasts! I've heard that the non-HDCD filter PMD designed was superior to others at the time (say, Philips or NPC)
Anyone know whether the oversampling filters found inside the OEM pmd100 and pmd200 chips are different from HDCD filter by itself?
That is, in rare devices like the Burr-Brown PCM1732 delta-sigma 96k dac chip, that feature HDCD filtering, is the non-HDCD interpolating filter (that PMD supposedly designed (for use with non-HDCDs) also being used?
When Microsoft software plays back HDCD, does it use the full oversampler?
Bottom line: I'm not interested in HDCD; but just how different companies approach interpolation for common Red Book digital.

Another set finally out the door. Thx COVID for all the delays.

Shout out to Dr Zeus for extending me the chance to own one of these, it’s a holy grail piece for sure even though it’s not totally complete. Good news: all the important bits are there, the board with the status LED’s is missing but I can probably make one since it’s just some lights on a PCB. Bad news: still need a lot of work- the chassis has corrosion, one of the large silver aluminum pieces that goes across the top is broken, and the middle part and plexiglass window is absent as well.

I will electronically restore this, and if all goes well I’ll see about having the missing stuff recast. But it’s gonna take time...

Hi all. First time posting on this forum, I have gotten alot of help over at el34world but I am looking for any more advice where I might find it. I am almost done designing a standalone preamp based on ceriatone chupacabra 50 for my friend. I currently am using valvewizard universal effects loop circuit as the effects loop/output but I am told that this will have significant distortion and impedance issues. I need V3B to output line level to an unbalanced input of a power amp (Like peavey classic 50/50). I have been reading the cathode follower sections at valvewizard but I am really struggling with the theory. I have built a few JCM800s but designing tube stages from scratch is a skill I am trying to learn.

Does anyone perhaps have a circuit I can use for an effects loop and output driver for this application? I do not mind adding more tubes or stages. Any advice really on how I can go about calculating component values? I really appreciate ANY advice, please let me know if I did not post enough information.

Iancanada FIFO Q3 and Reclock Pi (Retail of the Q3 was $125 and ReclockPi is still $75) - used $125

Well Tempered Master Clock Driscoll 5.6448MHz ($250 new plus $80 for the crystal) - SOLD

Iancanada Oven Kit for the SC-Cut crystal listed above ($39 retail) - SOLD

Iancanada UcPure ($87 retail) - new $75

Eaton 3000F/3.0VDC SuperCaps (retail $80 each) - SOLD

All together or separate. If you buy it all, I'll pay shipping in the US.

Free to good home, nicely built (in my opinion) zebrawood multi-layer plinth set up for 12" arm. Contact me if interested.

I'm retiring (for the second time) on May 12th. I'll have time on my hands to build more speakers and other equipment, so I'm kicking around the idea of building the ACA Redux. Would this be a good match for a MA A10-2, MA A7.3, MA CHP-70, MA CHR 70?As far as the CHP-70 and CHR-70, I have more than one pair, so I wouldn't mind putting two in an enclosure. Maybe a set of microTowers?
Thanks,
Mike

Fully functional. Pretty handy when experimenting. Too much stuff so selling.

$75 shipped?

This evening (2/24/2023) both my computers take forever to bring up the site.
Sometimes I can't even get on.... just shows a blank screen and no loading activity.
If I use the one computer (Win XP) which requires logging in each time, eventually I can bring up the site.
But on this the Win 10 computer, it takes forever. - the "scrolling" bar just keeps repeating.
I've checked my logon saved info, it seems ok.
other sites online are fine and load in a flash.
Any changes made recently?

Hello everyone, this is my first post. I am novice wrt. amps however I am enthusiastic about music and building speakers and DIY in general, just that the electronics side of things is not my strong point, however I am willing to learn.

I have this board: TPA3116d2 XH-M568 (or a clone of it). It's in no way 2x100W, other websites list it as 2x50W, identical layout.
My plan is to use it for a sound generator in a car, so it will be driven only at 13.8-14.4V when the alternator is running. For now, I am only using one output channel(L) with a 4ohm speaker, the other is open. I also am feeding a mono signal, on the input channel (L) that has a speaker(L), the other input(R) is open as well. I do understand that it's not a good idea to leave the other output channel open and this may fry the board. For input I am using one of the 3 inputs ports, present on the board, yet this does not matter, the board is apparently meant to be used with switchable inputs, I have just one source anyway, so I've selected Input1. So far, so good, it has decent power, probably not more than 10-15W on the 4ohm speaker. The sound is coming from an ESP32. The amplifier board has a stabilized 5V output which is very handy to drive the ESP32 without an additional stepdown regulator.

I have a couple of questions:
1) Should I connect the other output channel to the same 4ohm speaker? Is this possible with this board? I know that TPA3116 can be pBTL-ed, but I do not know the layout of this board. If so, how should the wiring be done, speaker connected to both + outputs, ore one output to be grounded?
2) In order to have more output power, I would need higher voltage. Is it safe to use a step-up buck converter in an automotive environment? Everything is fused and proper cable awg is used and the boards and ESP32 will be enclosed in an aluminum case, so if there is magic smoke at least there is some protection to it.

I know I could swap to a mono amp, yet I like the 5V output for the reasons mentioned above and I might want to run at some point a second speaker. Thank you in advance.

PS: I can post a link to the board if I am allowed to. This board is present on all big commercial sites.

Good day, gentlemen
due to lack of time to realize this project i offer it for sale.
I bought it a few years ago from a fellow forum member who wrote the following:
I have 2 packages of the GB offerred by Rudi Ratlos in 2016. I received them in 2017 and only opened up to see what was sent. One set is with the shunt regulation pcbs and the other is with the LT3062, as I thought I would like both. I also purchased an extra set of RC-100 and shunt boards from Rudy in 2019, as he wanted to get rid of them.
I can guarantee that you will not pay more than what I paid in 2016-17.` Let me know if any interest.
i don't want to make a profit either and would like the price of 190€ plus shipping that i paid at the time.

See attached pictures. Best regardso Sale

I've recently assembled a USB DAC with JLSOUNDS I2soverusb board with an I2S implementation of an AD1865 DAC.

The sound is perfect but when the DAC is 'engaged' by the PC/USB device there is a loud thump.

I have checked a few tests now - MOODE, VOLUMIO and USB AUDIO PLAYER PRO.

I can confirm each time the popping noise only happens when the player is 're-set'. For example, if the USB AUDIO PLAYER PRO app is closed and then re-opened, and the connection to the DAC is refreshed, there is a large pop. Or if I restart Volumio or Moode, it will give the loud popping noise. This happens whether using AC power or on battery of the computer.

I don't have a USB isolation device to break the ground to test, but I don't think it relates to a grounding issue.

Would adding a mute circuit assist in this case, or is there another work-around (apart from leaving the PC and DAC on 24/7!)?

@Mooly

Test.

Please forgive if this is a noob question.
So I picked up this blue tooth module. By team pie called the TDM157. It uses a AP8064 chip I will try and include the data sheet for this.

My issues. The chip seems to have many functions that have not been used by the guy who developed the PCB.
The other issue is that the response is not flat. I don't think this is a bad thing. But if I connect via blue tooth and send it a freq sweep. And I connect my scope to the output I see that the voltage change with freq.
How hard would it be for me to make a custom firmware. Where I can use all the special functions of the chip and maybe develop a custom eq.
Visited the site of the company who makes this chip. Did not see any SDK.
Lets assume this chip does not support a SDK for custom firmware what chip is there out there with the best SDK and support.

Sell the populated tested and working b1k board kit. Will build a second One with different components hence i sell this with prp resistors +4 100 ohm zfoil resistors that you see in the picture.sell for 160 Eur shipped to Europe. Price only for the board populated. If interested can sell the alps Blue with Pete board as well

Building a 30 watt class A amplifier using the attached LTSpice schematic and pcb layout. I have the prototype board set up on the test bench with a GW Instek GPE3323 regulated power supply, an OWON HDS242S for the scope and signal, and an OWON XDM1041 bench multi-meter.

First I tested without the output transistors installed. Power supply set to +/- 32 volts DC. The ground reference for signal and power are connected floating to the common of the power supply. All voltages at every node match the simulation results of the LTSpice run. With a 2Vpp signal I adjusted the bias to correspond with the voltage gain shown in the LTSpice run. All input signal voltage changes from 0.5Vpp to 2.6Vpp (clipping) thereafter matched and followed the corresponding LTSpice runs for signal gain. So far so good.

Connecting the output transistors (heat sinked plus fan), I adjusted the bias to 1.3 amps and the board ran at idle without issue over two hours, maintaining the bias current exactly at 1.3 amps. However, when I went to do a signal test and attached the signal generator lead to the pcb input, the power supply tripped at the cutoff current I set at 1.5 amps. Setting the current limit to the 3 amp max, the power supply still tripped and ran at constant voltage (about 5 volts).

No matter what I touch to the input node -- probe, rca cable, even a piece of wire -- the current draw increases (seems like it's shorting out somewhere). I even hooked up an rca cable from a cd player. Same thing, tripping the power supply.

I tried installing a 100K resistor between the signal input and ground upstream of the capacitor and removing the input capacitors. I tried tying the ground from the power supply common to the earth ground. Nothing changed.

I built another type of transistor amplifier using the same power supply and it works just fine. Never had the above issue while testing that one.

Appreciate any suggestions,
thank you

thanks

Hey All!

I recently completely reinstalled my AP 2.24 software and now I seem to be having a weird menu window scroll issue. After the install, the bottom of each of my tool windows has a horizontal side scroll that partial blocks some features from being used (Like Append or Single-Point on the Sweep Menu). I cannot manually resize any of the windows by clicking and dragging. I don't see anything related to this in the Utilities/Config or anywhere online. I'm sure it's probably something simple I'm overlooking, but can someone shed some light on this please. Thanks!

Hello everybody,
I'm now working on another power amplifier and I want it to have balanced inputs along with unbalanced ones. I did several balanced input preamps and amps with the "classic" one op-amp and three op-amps designs but I was looking for a higher performance solution (if there is one). After reading several articles and the chapters dedicated to this subject from D. Self's books, I decided to try and build the schematic below. From several sources on the net, this seems to be a very low noise solution. I do not need level control but I would implement a gain switch to be able to switch from high to low gain and I will add an unbalanced input as well (from the IN+ and GND connections).
If any of you have experience with these and maybe built something like this, I would like to hear your input. I'm open to other ideas as well. The only real downside I see on the schematic below, is that it uses 4x opamps per channel. For me, this is not a real concern as the LM4562 opamp that I use extensively is not that expensive and its performance is very good (ignore the LME49720 MPN from the schematic). From D. Self's book, there is a lower noise solution that uses 6x LM4562 but the noise difference from the schematic below is not that big (2dBu) and the one below is more tan enough for what I need.

Wanted Sony DVP-S9000ES Part Number FL-114 Interface Control Board. I reflow IC204 and it works for a few days then PCON dies and controls stop working. The IC shows signs of degrading in plastic. Personal DVD player for my Vintage 1999 Audio Video system.

Entire set of 16 Silmic 2 caps for the First Watt DIY Sony VFET R0 amp.

That's 16 caps: 8-off 47uF 35V and 8-off 220uF 35V.

£20 posted in the UK

For sale a oair if SE trans with 2,5 Kohm primary and 8 and 16 ohm secondary pkus 2 chokes 2H and 150mA.the transformers were taken from some old Copland amplifier. Iv used this for about 2 years now in my 2a3 amps. Working perfectly. This are abot 10x10x8cm big and weight about 3kg each. Plese look at pictures. Price for all four parts would be 90 euro plus shipping. Payment by paypal for friends.

I have a SUBZERO 20R (BluesJR clone) and I recently started to take interest in "bettering it".
I just did a small lead dress for starters and it really helped get rid of a lot of noise!
I am now considering changing the cheap trashy condensors for some more suitable substitute.

Would this help give the tone some more sweetness and lower the noise even more?
I'm thinking of replacing all of the Black Changx but am not sure about the rest of the red ones...

Very greatful for any insight because im just getting into all this mod stuff 🙂)





Pictures:

Hello, I am Danyixuan DiDiu1. From China, I have a simple way to introduce the work point of the electronic tube work point without labeling the circuit diagram.
I have used this method for more than 20 years, which is very accurate and convenient.