I'm having a hard time making acceptable quality digital recordings of an 8-bit computer synthesizer - that is with the line-out of the synth plugged into the line-in on my soundcard. The voices of the synth are programmable-frequency square wave generators.

Max level is 8-10 dB below clipping on record, but single discrete notes that sound pure directly from the synth acquire an annoying degree of "graininess" when recorded and played back - like there is a lot of FM modulation.

When playing chords of closely spaced keys in the same octave, additional and distinctly annoying artifacts are produced. It's present on the initial uncompressed WAV recordings but is exacerbated when the recording is compressed, which you can't avoid when uploading to a video sharing site.

The chord playing artifacts (especially after compression) make the digitally recorded audio sound remarkably like something being played back from a scratchy LP record.

The synth analog out has a single-pole roll-off at around 18 kHz. There is no undue noise or anything else.

I am wondering if there is still enough high-energy harmonic content in the squarewaves to play havoc with my audio cards digital sampling. My card is a not too flash Asus "Xonar" thing that set me back in the region of $35 maybe 10 years ago.

Has anyone else had similar experience or has enough insight into the robustness of anti-aliasing filtering on run-of-the-mill soundcards?

Hello,

I have two of those power supplies, from aliexpress: Nobsound 24V@6A 150W AC/DC Amplifier Power Supply.

Are those good for Amp Camp Amp?

I am going to build two balanced monoblocks (XLR connection).

Trying to bring a Acoustic 260 head back to life.
Had a blown fuse, replaced fuse and plugged it using my light bulb series power tester, bulb
stays fully lit.

Pull all four of the output transistors, easy to do as they are plug in socket mounted, short
is gone, bulb briefly lights bright and fades down to barely glowing.

Using a multimeter in diode test mode all transistors show they should be good.
Checked the two driver transistors the same way and they check good as well.

Output transistors are 40411 NPN RCA's

Anyone else dove into one these, schematics seem to be non existent,

Would it be worth just replacing the outputs with something like a set of MJ15024 or 2N3773 transistors and see
where that takes me?

Mike C.

Hi,
I have a class a se amp project with EL84 tube. But I can't find output transformer in my country. I am looking for the winding technical information of the transformer with technical data below.
-Primary part wire cross-section and number of turns.
-Secondary part wire cross-section and number of turns.
I'm sorry, my English is not very good.

Primary impedance : 5K
Secondary impedance : 0 - 4 - 8 ohm
frequency response : 20Hz ~ 40KHz
output power : 8 ~10 watt

Hi I just purchase Topping Pre90 and connected to ML 5302 using both XLR input from my DAC and XLR output to amp. I double check the connection, turn the power on Pre90 and turn the power on ML 5302 and almost blow up my speaker. Luckily protection circuit was kick in and disconnecting save my speakers. Any idea what is going on?
The DAC was off and there is no source signal. Pre90 volume was set at safe level -40 dB. Defective units? I purchased the Pre90 because of such good reviews but very disappointed. Thanks

Hi
I am looking to add another pair of outputs to an old car stereo head, so there are 6 instead of 4 (pre-amp level) channels out, all with the same output level.

So - I am looking to take one of those stereo pairs and duplicate them, with the resulting pairs being the same output level as the single outputs with some sort of buffer amplifiers (so I have three stereo pairs coming from the amp, albeit with two of those tied together on the fader control).

This is presumably a basic generic circuit - but I can't find quite what I'm looking for on the web, or the name this sort of circuit goes by (buffered splitter?).

I don't know what the exact output levels coming from the stereo head pre-amp channels are, but they must be within standard range because it works ok on several different car amps.

Making a circuit board is no problem, but I am after some advice on the right design for this purpose. Or else perhaps there is a cheap Ali-express unit which does this job for pennys (what would that item be called?) - though I am happy to make my own DIY board.

Thanks

What projects can I build around a pair of 400VA Toroidy Supremes which only have a single 25vac secondary?

After stripping down some monster amps I have many components for sale including these , any good to anyone?
Offers .

This is not often discussed, but I've been told that adding an R-C network to some tweeters helpd to refine their sound. I came across this on the LDSG:
"The MDT33 tweeter has a very devoted following. Some have also recommended the use of a Zobel to sweeten the top end."

Your thoughts/experiences?

TIA

Neil

After 18 years challenging myself, learning from you and sharing nice projects I will leave this forum.
Also because being bullied and get physical threads without support of the moderators for the last 18 years.
See you all on the next forum.

R.I.P by mod.

Hi guys,
First of all I should mention that I’m not in the league of many of you , I’ve changed a few capacitors and upgraded cables on amps and speakers , I now have these huge power amps which I believe haven’t been switched on for about 10 years, I wish to power them up myself but can this only be done safely with a variac ? And if so how do I know how many amps the variac needs to be etc . They are 240v and I’m told are 1000w ( output) each .
Obviously I don’t want to simply plug them in and hope for the best so what’s the best plan of action please?

I'm playing with both QuickPanel and Front Panel Designer, seeing how the prices and software compare. I find the instant online quotes pretty impressive. Schaeffer appear to be more expensive but the software is better in my opinion.
Quickpanel only has one font loaded in.
Is there an easy way to load in the fonts we would find in our computers in Windows for instance .? The tutorial on adding text which I assume is maybe a vector type is way beyond my pay grade.!

.

I used to have a pair of DTS10 subs in my last HT (which I loved), but I sold them when I moved...plus they would be too big for my current location. I am looking for a design for a tapped sub that is 3' wide, 2-3' tall, and 2' deep. I would like it to go flat 40-60Hz down to 20hz (corner loaded with concrete floors, and walls), and prefer an inexpensive woofer (woofer prices have skyrocketed in the past 5 years). The sub will go under my K402MEH horns...hence the dimensions I listed. I would like it to be able to put out about 120db @1 meter and will be powered by a Icepower 125asx BTL amp module.

New loudspeakers - unpacked, tried and returned to the box.
Walnut finish.
They sound sublime.
Price would be 2100EUR.

I have an old PSPICE schematic that I would like to plot. I went to Orcad and started the process of downloading the "free" version, but it seems they want to sell you a complete CAD system. You have to send a request, get an email, ... It's not really worth it for me. If I could run an old version, that would be fine, and just PSPICE, no CAD stuff. I have mostly repeated my work in LTC spice, so the need for a PSPICE viewer diminishes. But I would still like a small simple file viewer. Any suggestions?

Hi

Im doing a my first "real" 2-way speaker design, i have have dabbled before with few designs but this time will do it correctly taking time, measuring, building foamcore prototypes and modeling with vituixcad.

Thing is that i am wondering, is could active crossover help with design? (My midwoofer is Audio Technology 18H52)
I would need to try few crossover points to find out which could work out best for my taste, like 1600hz, 2200hz, 3000hz, 3400hz etc..
(with particular tweeter im testing)


Active could help out making this easy to try what i like, so i will know what crossover point i will take when i start modeling, right?

Hi Guys,

I bought this Class A board. The auction states 28v is ok. On the board itself it says 33v +-

The auction also states 30va is good enough. So I bought a 50va 25v stuck it in the 6a (I think) bridge rectifier and got out 56v.

I presume this is 56v +- so I stuck it in the 33+- and got a loud buzzing.

I'm probably doing a thousand things wrong!

Thanks in advance!

Hi everyone

im curious if any has way too much and wants to sell a little

thanks!

What are the recommended fuses to be used for each of these Amps to make MAX power and what are you getting with the fuse amperage you are using?

BT2180 = 2 x 180w UcD OEMLP modules
BT4180 = 4 x 180w UcD OEMLP modules
BT2250 = 2 x 250w UcD OEMLP modules
BT4250 = 4 x 250w UcD OEMLP modules
BT6180 = 6 x 180w UcD OEMLP modules
BT2700-2 = 2 x 700w UcD OEMLP modules

Hello all

So I have been playing with this amp for a bit and reading the fourth edition of Valve Amplifiers. I have finally gotten the output to be a decent voltage without distortion. However I am running into the issue that lower frequencies really drop in voltage and the higher frequencies spike. cant seem to figure out how to address this, any advice will be appreciated, if my design sucks, please tell me.

This amp uses IRF640 for the outputs .

Wondering will the 640N’s work in the amp ?

I am considering purchasing a set of Revels. The Ultimate Studio. Not the 2 version. Anybody have a pair out there?? Was listening to them in a dedicated showroom that was set up for listening. The speakers were on the short wall shooting down the length. Room was about12' wide by 18 long. I heard and also measured with FFT on phone a huge suckout at 40-50 hz. This was straddled by big peaks at 60hz and 30hz. Just wondering if anyone has in home measurements on this speaker? Saw a Stereophile review that show a shallow suckout at the same frequency about 2-3db. What I was measuring was about 20db!!

FS: Troels Gravesen's Nomex 164 mkII

SOLD


For sale a beautiful set of these really good sounding 2.5 ways towers!

New price request 500€ + shipping costs (to be defined, in case).

You can see the pictures of them at this dropbox folder link.

The items are in Italy (Florence), built by myself at the end of last year.
I'm selling them because I'm moving to a new house and there will not be enough space for them (at least this is my wife idea, and I had to follow her decision!).

They are well built and sound really good. Veneer is still to be applied, so you can choose the finish.

At this page you can find all the technical informations.

I can ship without problem, and I can ensure a solid and secure box; anyway, it will take me some time to prepare it and for sure the shipping will be a little expensive (not my fault, I will not ask anything for materials and labour).

Of course picking them in person after listening is more then welcome!

Waiting for your response,
best.
Giacomo!

Looking for an Aphex 124 unbalanced to balanced line convertor prefer UK sourced but WW considered if total cost, shipping & taxes is reasonable

Hi,
I have a pair of NS1000m (s) but am aware that they are "old" with unobtainable parts. I love the dynamic midrange.

I perceive that the large magnet, and hard dome are the primary contributors to the efficiency and transparency.

Therefore in the 21st century, are there any drivers which offer similar performance, particularly embodying the qualities that I think the NS1000 mid excel at:

dynamics / transients
transparency
efficiency

My ongoing search for the perfect mid lead me to acquiring some ceramic magnet 5" Accutons, but they are not particularly efficient.

Budget: ideally less than £100 each, but flexible, current ish production.

I have multiple speaker projects on the go at present, mostly waiting for my time and workshop to be finished, (almost is!!!) so this is a slow moving request...

Thank you for humoring me in my quest for the perfect mid.


Current speaker projects for the curios:

Shackman based 2 way. Parts acquired.

Bozak homage, Bandor 2" and Monitor Audio 10" bass (active, current drive) in Goodmans Magnum box! parts aquired.

monster LX5... Linaeum tweeters, Accuton mid Kef B139 bass (4 per side). parts acquired.

Serviceable 3 way monitor / NS1000 clone. still in the thought phase.

I'm experimenting with a bi-amping setup. The active crossover used is an a/d/s/ 642ix car electronic crossover. It has a feature that allows it to feed subwoofer signal, i.e. bass lower than 80 Hz filtered by subwoofer channel low-pass, to main speakers. The main speaker is a floor-standing type with two 10-inch woofers per side. The subwoofer signal would be set to MONO operation. My question is whether I need to use a "band-pass" filter on the woofers of the main speaker. Or can I use the main speaker as a full-range speaker? Because the subwoofer signal is set to mono and will be fed to the main speakers, I'm concerned that the stereo bass of the woofers and the mono bass of the subwoofer signal will interfere with each other.

System configuration:

(A) Run the main speaker as a full-range.
Tweeter = 5 k - 20 kHz
Midrange = 500 - 5 kHz
Woofer = 20 - 500 Hz
Subwoofer (fed to the woofer) = 20 - 80 Hz

(B) Apply a band-pass filter to the woofer.
Tweeter = 5 k - 20 kHz
Midrange = 500 - 5 kHz
Woofer = 80 - 500 Hz
Subwoofer (fed to the woofer) = 20 - 80 Hz

Which option should be chosen? Please advise.

Help needed…

I dug out these two stereo LM1875 boards from my parts bin, looked up the supply spec from the data sheet and have hooked up a twin secondary 15-0-15 80VA supply that I had on hand, I figured this would be good for testing four chips.

These boards utilise a dedicated AC/DC regulation chip KPB307 per LM1875 chip that with along with 2x1000uf 35v CAPS per rail should provide approx 19-20vdc dependant on mains supply by my rough calculation which is within specification of the chip.

As these boards are off the shelf I made assumptions that they would be plug n play. I tested to see if resistors were in spec and soldered properly. One resistor required replacing due to mechanical damage.

So I used a 2amp quick blow resistor and powered up but quickly noticed burning smell, powered it down and have noticed casing of one chip has split.

Have I made a grave error that has caused the damage to the chip or is this likely a failure of a dodgy fake chip?

The chips do not appear to match the genuine case format of lm1875 on data sheet.

I have removed some cables during test so this is not reflective of how it was when powered up as some wires not present in pic.

As the title says, I found a nice HP 333A locally on Craigslist for $25 and although I already have a QA400 I thought why not at that price. The unit is quite clean and the guy I bought it from told me he picked it up from the lab that he worked at where they were getting rid of a bunch of old equipment. The RMS voltmeter is pretty much spot on and works great, the distortion meter however is not working all that great.

I tested it on one of my Aleph's and the QA400 was showing about .12% distortion under test where the 333A shows about .7% distortion. The unit nulled the signal manually and it seemed that the auto nulling was working fine as well when it was switched in.

I have searched the net a bit and I have the service manual. I noticed that a lot of people are replacing the dated electrolytics. A quick glance in mine shows a lot of 1975 date codes on the caps. I'm going to go through the steps outlined in section 5-40 of the manual for troubleshooting the distortion function. I was just wondering if some of you folks that are quite familiar with the HP equipment have any tips or things to check when the dist. meter is out of line?

Its not easy being a loudspeaker designer and it likely take years to understand what to look for and in part to chose what to give up. I have been reading books and articles for a long time, but spite this, I sometimes feel stupider than when I started... LOL, and this time I want to focus on open baffle driver specifications. So lets look at what is commonly said about drivers.

One factor or indicator to look at is the EBP (Efficient Bandwidth Product) – The efficiency bandwidth product is a rough indicator measure. A common rule of thumb indicates that for when EBP >100, the driver is perhaps best used in a vented enclosure (ported, aperiodic and transmission line), while EBP<50 indicates a sealed enclosure. For EBP 50><100 either enclosure may be used effectively. Because a sealed cabinet offers cone or membrane support to a higher degree than in open air, the requirements of the suspension is different. The former can be looser so to speak. Lets check if this is correct

I am going to use two drivers from SB Audience because they perfectly encapsulate the issue at hand. Both drivers are 12". Driver #1 is the BIANCO-12OB150-01 which is marketed as an open baffle driver. Driver #2 is the BIANCO-12MW200 "non OB. According to the theory, the open baffle driver should have better suspension compliance and higher EPB values.

Driver - efficiency - Qms - Le - CMS - Rms - EPB

1) BIANCO-12OB150-01 (OB) - 96dB - 6.39 - 1.18mH - 0.25mm/N - 2.26kg/s - 64
2) BIANCO-12MW200 (non OB) - 99dB - 14.33 - 0.38mH - 0.15mm/N - 1.45kg/s - 100

Qms: A unitless measurement, characterizing the mechanical damping of the driver, that is, the losses in the suspension (surround and spider). It varies roughly between 0.5 and 10, with a typical value around 3. High Qms indicates lower mechanical losses, and low Qms indicates higher losses.
Cms: Measured in meter per newton (m/N). Describes the compliance (i.e., the inverse of stiffness) of the suspension. The more compliant a suspension system is, the lower its stiffness - The higher the force on the cone and suspension assembly the further it travels.

If we look at both Qms and Cms we can see that the are inverse to one another. As the Qms increases, Cms will decrease. An open baffle driver should therefore and theoretically have a high Qms and low Cms to be stiff enough to withstand external forces, compared to a driver mounted to a finite cabinet like mentioned before. Also, if we have a stiff suspension and high efficiency, all the better and together with a low Le, such a driver should be well suited for an open air operation or open baffle.

Q: Why then is the driver with less stiffness and less EBP (BIANCO-12OB150-01) recommended for open baffle ?

Sources:
1. https://en.wikipedia.org/wiki/Thiele/Small_parameters
2 http://www.sbaudience.com/index.php/products/woofers/bianco-12mw200/
3 http://www.sbaudience.com/index.php/products/open-baffle-drivers/bianco-12ob150/

I’m curious about few things and I would like to know!

I have built several stages of DIY phono, some published in DIYAUDIO, but I always have the doubt that is what gives good dynamics to a preamplifier.

I have passive phono preamps; assets; mixed some I like their sound but they do not have good dynamics and vice versa.

In all of them I use the same power source (50 watts and ultra-fast diodes); and the rest of the audio system is the same

Please what is the factor for good dynamics to be obtained?

Fs Samwha 10000uf 63v caps 4 pin 105oc x11 unsed. Moving some more items on I have more than enough of.

Someone take them all £25 shipped to the UK.

I have an old Dac Magic DAC that takes 12V AC input from a wall wart plug. I measured the input voltage at 14V AC with the load on. I have heard many stories of improved sound with a larger/better transformer.....So I though well I have this huge oversize 16A Variac, so why not turn this down and try it before spending money on a dedicated 'better' transformer. Well I did, and when it was turned down to 14V I plugged into the DAC Magic, and it tripped the main 100A house RCD, not even the local consumer unit one I dedicate to the Hifi Circuit?!? so I tied it again, and the same thing happened.

I have taken the Neutral to the -ve and the Live to the +ve of the transformer secondary into the 2.5mm plug into the DMagic.

I figure this has something to do with the Earth and Neutral connections on the output of the Variac, but I thought the trip from an RCD was if you used the earth as a return not neutral?

Confused!?!?!

Thanks

I am working on a differential tube preamp with a CCS for the LTP. I would like to design a low noise, high impedance current source with reasonable temperature stability and would like to understand the pros and cons of using a BJT vs JFET vs MOSFET. I am looking for 10-15mA and have about 25V to work with. I don't mind some circuit complexity (although I don't have tons of space) or spending some $$ to get the best performance.

I was considering an op-amp based circuit using a precision voltage reference driving a MOSFET, but I'm not sure if this would deliver the best performance.

Thanks for any assistance.

I've bought a job lot of parts and these were part of it, they are regulators I know that, print on pcbs say diyaudio layout by Jens Rasmussen 2006, could anyone point me in the right direction to any documentation?

I have a pair of 3 way floor standing speakers, on the back of the speaker cabinets it says they are: 180 watts, Impedence 8 ohm, Sensitivity 92 dB, Frequency 35hz- 25Khz. But inside on the back of the speaker cones it says 6 ohm are my speakers 6 or 8 ohm, i'm upgrading to a new amp what should i buy a 6 ohm or 8 ohm amp

Hi,

I'm screwing TO-220 and TO-264 transistors onto a heatsink. Any tips on type of screw, washer etc. to make a good thermal solution that is also durable with years of thermal cycling?

In my case, it's OK that the transistor package, heatsink (probably Cu) and screw are electrically connected.

It could be so easy that what I'm looking for is M3 screws, a drop of Loctite and a springy washer. Of these, locating the right kind of washer is probably the hardest part since it must prevent overtorquing and thermal expansion / contraction from breaking the transistor while maintaining thermal conduction.

Thanks,
Børge

Wanted pair of Viawave GRT145-4, must be 4 ohm version.

Used or old stock from before the war broke out please.

Hi, I have a used HP 8903A audio analyzer for sale if anyone is interested in the UK? Surplus to requirements since I now have a better one. Asking price is 499 GBP with free mainland UK postage. Please PM me if interested.

Is 5534 still a good choice for audio amp (pre-amp) design?

Ok So I got a Dual cs430 on the bench for repair with speed problems.
The external adaptor/ power supply was gone (12vdc 20mA). Pretty simple affair (transformer/bridge/cap & no stabilization)
So I replaced it with a new one.
Now the problem is a little bit better but it still turns to slowly and not stable.
The belt has been replaced and is OK.
12v DC is coming in ok.
Only thing really left is the DC motor itself. It says DC205.
Problem is I can't find a replacement for it. I found Dualfred but he doesn't have it either.

I read online that the electronic control is inside the motor itself.
The TT itself is nothing special. DC power comes in trough a switch in the arm. And there is a 33/45rpm switch that connectos to the motor also. That's it.
If anyone has a solution fort this, it would be great.

Best Regards
Jurgen

Finally finished my speakers. Diy open baffle subwoofer with 2x Eminence Beta 5, 8Ohm in series on a 1.5x1.5m semi open baffle. Two 3 way satellite tall slim speakers. Minidsp, 2xICEPower125asx2, Behringer A800. First i was building the lxmini with the speaker drivers but I was not happy with the sound result for my beloved music, so i switched back to closed speaker for the satellites crossed over at 80hz. Woofer 80-1lHz, midrange 1-3kHz, tweeter 3kHz and up. The built video is here: Login to view embedded media

Like to hear opinions about this and possible usage senarios?

AK4191EQ | Audio D/A Converters | PRODUCTS | Asahi Kasei Microdevices (AKM)

Amp is pretty much the same as Fusion-FP9001D. Schematics are in Perry's guide.
Some guy tried to fix it, but made more damage to the amp than anything good. Output section was totally dead.

I've changed so far:
Hip4080 -->new one from reputable source
CA3290 --> NE5532
CD4069UBM --> new one from reputable source
CA5470 --> TLC2274ACN
Couple of resistors and caps. Took out the mosfets (they were indeed shorted).
I could NOT change the CD4013B as it's unavailable in my region anywhere due to supply issues.

Amp now starts but the FLIP FLOP CD4013B shuts down the hip4080 thru pin 3 going high. I do have all the +12v, +6v from the regulator.

When driven to clipping at the RCA input I see a small square wave modulated at pin 7 of the HIP4080 riding the 6v DC.

Pin 5 has 105khz square wave.
Pin 6 has the triangle wave.
Pin 1 and 2 have their 12v.
Only issue is pin 3 have 12.5v on it too, so the ic stays disabled.
Overload led stays on all the time.
Could not find any resistor out of tolerance, bad diode, or shorted transistor. I still can't wrap my head around the Truth table for CD4013B.

If it is helpful i can post voltages of any chip.

I kind-a hate this amp layout as everything is on vertical driver boards.

I have a Umik-1 microphone and REW

A 350va 2 x 120v primary 2 x 30v secondary toroidal for sale, its branded Farnell but its made by Avel. Primary have terminals on them but can be removed, please see pic.

£25 with £8 postage to UK only

I know it won't win awards for looks but I always wanted to make a ribbon mic. the ribbon is just ordinary aluminum foil, the magnets are neodymium and the step up xformer is from a sony tv.

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FOR SALE: Morel Supreme Tweeter ST-1108 PAIR, Soft Dome Matched, Works, 8 ohm, Silver Faceplate, see the 10 Pics below​

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1-1/8" Soft Dome Tweeter Pair with Silver face plate. They were used for a project, probably have about 300 hours on them.

In good working condition, both work well, been stored in their own boxes, missing one clear plastic storage cover, I just tested them again recently, both are good. Domes and housing are in good shape, Metal housing is clean without any damage, one dome appears to have a very slight tiny indent but very hard to see. Please see all the pics for best description and condition. Size: 110mm (4.33") x 40mm(1.57")

Asking $325 for the pair + $12 USPS Priority Shipping with tracking to lower 48, Prefer Payment made with ZELLE or PayPal "Friends & Family", Paypal Fee's are extra. Will be promptly packed up and shipped to you. Local Pickup in (LA) is also welcomed.

Please feel free to ask me any questions or if need more info or pics. Thanks for looking.

Typical retail price is approx. $640/pair and this is the hard to find silver face version.

Manufactuer & Model info Link: https://www.morelhifi.com/product/st-1108/

Link to tear sheet with specs: https://www.parts-express.com/pedocs/specs/277-096--morel-st-1108-black-spec-sheet.pdf

Underhung voice coil
Large Hexatech™ aluminum voice coil
110mm IDR™ Improved Dispersion Recess
Replaceable Acuflex™ dome/coil assembly
Aluminum Face Plate
Neodymium flat pancake design magnet
High power handling

Nominal Impedance Z 8Ω
DC Resistance Re 5.2Ω
Voice Coil Inductance @ 1KHz LBM: 0.09mH




















close up of right tweeter

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Authentic Toshiba NOS 2Sk170BL

I've got 64 of these that need to go

I will say selling no longer matched as not alot of interest now dirt cheap for original Toshiba

£1 each or all for £50 plus shipping at cost

For sale very known tube tester AVO CT160. Fully functional and in great shape. 1000€

Also, I have Tektronix 575 Curve Tracer for sale, fully functional. 300€

Location Croatia, Europe. I prefer local pickup, but would consider shipping to EU countries only (only AVO CT160, Tektronix is too heavy).

Trying to repair one of my two nx 3000
Red light protection on channel B so no sound in this channel
It was connected to 2 Electovoice zx200
I’ve the shematic but really not gifted in electronics
There’s no repair shop in all the city where I live
do these amps have common problems?

I need help identifying this system.It is well constructed including tying the foil on the capacitors to ground.I have started restoration that will begin with drawing a schematic for it.I would be grateful for any info.Thanks

Looking for some direction for resolving an issue of it displaying "OVERLOAD". I am aware of what the user manual says, but I have this amp on the bench with only the power supply connected.

This is an AD844 IV stage with OPA627 buffer at the output. I got the Gerber file posted by a member here some time ago and recently done up a few boards since I have 5 of them (MOQ by JLCPCB).
DC can be easily trimmed using the trimmer at the AD844 and measured at pin5. Then it can be trimmed out again at the trimmer at OPA627. Holds at zero Volts DC using 300mV range on my FLuke multimeter, rock steady all the time. No caps needed at all at the output. I am using 1.5k as the IV resistor and running this board for my Miro AD1862 dac.

65usd net , shipped to your country.

I picked up a small batch of 12C5 power pentodes with the "Coronado" brand. One has the octagonal "stop sign" with 12C5/12CU5 inside, one looks like typical Sylvania marking. Has anyone else encountered this brand. The parent company is Gamble-Skogmo out of Minneapolis.

https://phys.org/news/2022-11-rats-bopping-video-innate-synchronization.html

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dave

getting to grips with designing my own speakers I want to use a sealed box and have been inputting lots of different drivers into a website calculator however I've noticed a few different results than the manufacturer recommends. having tried a different websites calculator I'm getting wildly different results for the same drivers . is there a reliable app that anyone recommends for android or a particularly good calculator I could use through Google please .the two I've tried so far are the hifi audio design sealed box calculator and the aj design calculator
thanks in advance

I just wanted to share some photos of these parts that came today.

These waveguides are were designed using ATH and Fusion 360, then 3D printed in resin by JLCPCB.com and they were cheap, too! About $10 + shipping. I got some in black and some in white. I added a note to tell them only use printing supports (help them to print it) on the back so the front stays good looking.

I made my own using FDM 3d printing first for testing the acoustics, but you see the rough layers using that method (looks rather DIY). These look really smooth and have great detail. There are a few minor scuff marks but they are barely noticeable. I'll be spray painting them anyway, but I'm very pleased 🙂

If you don't have a 3D printer or want more professional looking detailed parts I'm happy to give a recommendation to JLC.

I have put together all of the original documentation I have on the GAS head amp and have posted it for everyone's edification. After reviewing it I can see a glaring error. The bias setup for version 2, board #334, shows the wrong PCB layout. Suffices to say that there should be 1 volt across the 51 ohm resistor R20 and also across resistor R25 in the output section.

There ya go. Hope this helps someone.

Hi boys,
I would like to know how much inductance and capacitance metal film resistors generate when used in audio amps circuits. How much percentage value would be that?
Thanks in advance 👍

Hi,
while at a friends house, I Spotted a pair of 'Acoustic Research AR-7' bookshelf speakers. Doing a bit of googling, I was surprised to discover that these are supposedly quite good speakers, praised for flat frequency response and revealing sound. I am wondering how much speakers have developed since the 70's, since if they really are good, revealing speakers, then I would like to use them in a recording studio as monitors, but if 'good' means anything between 120-14kHz by 70s standards, then I might not bother. 🙂 Does anyone know anything about these speakers? And would an old pair be likely in need of £££ of restoration?

Thanks

Hello, newbie looking for some suggestion on resurrecting my old Class A/B amplifier after a catastrophic failure.

Here's the tale, so for the best of my luck when I was checking the bias mA on my Samson S700 amplifier for note them down as maintenance routine, somehow when I powered the amp the test alligator clip slides from the output emitter pin touching other pin or the nearest resistor and I quickly turned the unit off after a smelly big smoke cloud, this is the first time this silly thing happens to me tbh, really frustrating situation.

Now the amp channel 1 module has two failed transistors one pair 2SA1492 / 2SC3856, two small 1/2W burned base resistors, tree open/burned 0.47ohms 5W emitter resistors and the unobtanium 2SJ78 / 2SK215 lateral MOSFET's.😱

Since there is no 2SC3856 avail at Mouser, Newark nor Digi-Key and since eBay is full of fakes to bother with, I opted for all the pair 2SA1943N / 2SC5200N(2SA1386A/2SC3519A was pricey) as I've read some threads users using them as replacements and they are a tad better, also listed by the NTE as replacement too.

So I ordered all the parts, 6 pairs 2SA1943N / 2SC5200N and the silicon thermal pads, all the small base/emitter 1/2W resistors, all 12x 0.47ohms 5W emitter output resistors.

However I'm now stuck at trying to find 2 pairs 2SJ78 / 2SK215(or 2SJ79/2SK216) lateral mosfets from any reputable sources to no avail, and the ones I've found under the U.S. location are a bit pricey for being NOS parts if that's even the case.😒

All this frustration made me spent lots of time searching/compare for those laterals mosfets and I almost to execute an absurd experimentation, just replacing the 2SJ78 with -> ECX10P20 and the 2SK215 with -> ECX10N20, I know those laterals are way overkill for the role of pre-drivers but I could not find anything similar in the case TO-220 unfortunately.🤔

So the question is, after re-biasing the amp does this big laterals can work as drivers in place of the unobtanium/obsolete 2SJ78 / 2SK215, and what could be the drawbacks of using such large/overkill laterals instead the smaller with less input capacitance, I guess the amp may be prone to oscillation at high frequencies and/or lower amplifier gain? assuming this overkill laterals can work as drivers of course.

Also is there another/better 2SJ78/2SK215 replacement candidates with similar specs regardless of the gate/drain pin configuration, I'm up for options/experimentation.

Amp channel modules cleanup/preparation started:


Regards

Moving soon so I need to sell some heavier stuff. Have these great amp building books that I no longer need.

Books by Kevin O'Connor - $60 each plus shipping (can make a deal for multiple purchases):

The Ultimate Tone Volume 1
The Ultimate Tone Volume 2
The Ultimate Tone Volume 4
The Ultimate Tone Tonnes of Tone

Books by Melin Blencowe - $40 each plus shipping (these are the out of print first editions in excellent condition):

Designing Power Supplies for Valve Amplifiers
Designing Tube Preamps for Guitar and Bass

Pictures:

Please message for any questions. Thanks!

Roman

Hi,

Still continuing to have fun learning about things, I thought I'd kill two birds with one stone and learn Tina TI, whilst figuring out how to design a simple composite amp using the LM3886 as the power amp.

It took quite a bit of playing around with the circuit but I think I've found something that works*.

First things first I wanted to keep it as simple as possible, so no balanced inputs or DC servo (I think I'm correct in assuming that a DC servo replaces the DC coupling cap at the input).

I also modelled the standard LM3886 amp with all the stability components to get a THD baseline. With a 1kHz base frequency, Tina TI's Fourier Series analysis reports a harmonic distortion of 0.054%. I know this is based on "ideal" components, and doesn't take into account parasitics and PCB layout, etc., but it's a useful baseline.

The composite version, using a LME49710 I've got the HD down to 0.0027, which is around a 20x reduction!

I've also tested it with 10kHz square waves with various capacitances across the load, and the square wave is stable (it took adding in C8 to achieve this, as before, any square wave would oscillate wildly; I also tried using Cf and Rf2, and while this helped with the stability, it affected the distortion to the non-composite levels).

*the one area it definitely falls over is at clipping. Something catastrophic happens when the amp goes into clipping, so that will need fixing.

I guess my questions are, what additional components do I need to make this a successful design, and do I need to move anything around? I was a bit confused as to whether stability components go in the inner loop, or the outer one, or if they're needed at all.

Any and all feedback gratefully received. Thanks for your time!

Attachments: Schematic, FFT analysis, FFT graphs (phase plot a bit weird?), Square wave @ 10nF, Square wave @ 100nF, Square wave @ 1uF, Clipping, FFT analysis of standard LM3886 circuit (all at 21x gain)

I managed to break one by applying to much soldering heat. They are however not available to buy in small quantities. Minimum is 2000 and it will take months.
I have ofc checked ebay etc but nothing.

Anyone know where I can find them?

https://www.nisshinbo-microdevices.co.jp/en/products/audio-switch/spec/?product=njw1112

I've seen photos of these speakers around the place and I always wondered, what's the effect of having two open baffle woofers arranged like this?

To my mind it seems like it will still perform the same as a single di-pole configuration, won't it? Do we get more sensitivity?



https://www.dagogo.com/legacy-audio-whisper-dsw-review-part-1-of-3-what-if/

UNTESTED
BEST OFFER

Pics are of 2 sets of 4 tubes

8 total

Anyone know what outputs are being used in this amp ?

I received it and all outputs are missing

Selling 2 PSE 144 Synergy horns.
$1600 and you pay for shipping from Destin FL 32541.
$1500 if you willing to wire the crossovers yourself. They will be in 2 large shipping boxes 56” x 24” 24”.
P.S. I also have 4 spare mids for them - Celestions TF041MF $80 for all 4. (used)
Description is below.
No-compromise Point source loudspeaker, free from of distracting cues that makes us aware we are listening to a loudspeaker. The acoustic image is precise and cohesive. • Extreme dynamics and details • Imaging vastly better than ANY 2-3 ways speakers • Ability to move within the room and the sound from the PSEs does not change • Better details - hearing lots of stuff on familiar music I've never heard before

FS matched components that were originally part of the F5X group buy. I've only got the parts for this as was part of a bulk buy I've bought, components as listed,

Semi's
Matched 2sk170bl x4
Matched 2sj74bl x4
Matched 2sj201 x4
Matched 2sk1530 x4

Plus kerathern isolation pads

Resistors
Mpc74 0.47r 2 x lots of 8 matched to 0.1mv
Mpc74 0.22r 2 x lots of 8 matched to 0.1mv

Prp resistors 33r 1/4watt 3 lots of 8 Matched
Prp resistors 220r 1 watt 4 lots of 8 Matched


£100 plus postage at cost anywhere

I used it to work on my turntable. No longer needed. Works perfectly well. Some scratches on top, otherwise in great shape.

Sansui TA-2050 in excellent condition. Original arm tube replaced with carbon fiber. Headshell is removable carbon fiber and can rotate to set azimuth. Internal wire replaced with 5/9s silver wire with Teflon insulation. Gold RCA termination box for STD cables. Original cue mech included (for std Sansui table). All bearings checked and are in excellent condition. Arm operates as it should. Mounting hardware included.

Arm length increased to STD 9"

This was Sansui's top of the line arm. This arm now competes with my Fidelity Research FR-24 MKII.

Asking $190.

So I'm trying to replace the sub on my PC setup.
My current sub is part of an ancient Logitech Z-5500 setup, which has a 10" sub, and I've been very happy with it.
Can anyone give me some info/opinions on which would be better between the Dayton or Monoprice?
I like the larger driver of the MP, but the Dayton has a good rep among the searches I've done also. I just can't tell which would be the better option overall.
I would be connecting it to something like this (probably), most likely via the sub out, unless I can't for some unforeseen reason.

Just an idle thought and I've not yet put the numbers into a box program.
Has anybody used the SBAudience Bianco 15" woofer other than as an OB, IG not Ripole etc.
Somebody is selling a pair for a reasonable cost and I was wondering if it was worth the experiment as i like big speakers etc

Hi

I keep seeing numbers between 250-450kHz being the "standard" for class D audio. However, I can't seem to find why this is actually the case. I figure that as the frequency ^ we get more PWM of the audio input, but why wouldn't I then just go for the highest frequency? Is it due to noise?
I read

Note: I'm using a comparator + integrator configuration to generate a triangle as the reference.

Is there any reason why 0.12 ohms is the chosen value of the total resistance in the crc section of the power supply.
Is this a good all-round figure to go for that gives decent levels of noise filtering, and there would not be much benefit in increasing this value. The resistance value does not seem to take into acount that there maybe different levels of noise due to how clean the mains ac supply is.
Thanks

Hy I would like to replace capacitors in my Pioneer CS-770 speakers.
There is a pair of 2,7uf 63v in each box...
Should I use electrolityc or film?
Any brand recommendations?
Speakers are 3 way, 6ohm 110w...

This is a 48v, carbon brushes motor. Took months to complete the order during which time i moved onto a dual synchronous motor setup and lost all interest in pursuing DC motors.

EU duties came to about 85€. Asking 150€ + 10€ shipping + PP charges. Shipping only within EU.

Will stay here for about a week before Ebay.