Hi everyone, I have just purchased one of these, and I would like to convert it to 230v, I've opened it up, there is a link on 115v, can I desolder it and move it to the 230v holes and resolder it?



Any help would be greatly appreciated

I have been given a NAD 3020A which is working well apart from a loud pop through mainly the right channel when I switch it off. This happens at the same volume regardless of volume setting and also happens through headphones when connected. I am currently working round it by plugging a jack plug into the headphone socket on switch off. Is this a common fault which is easy to fix or does it need someone more skilled than me to fix it.

I have the amp built and left channel works great. I have checked all solder points. On board 1 if I test vtage points on the left side it tests 3.7 volts under load. The right side is double digits. I cannot figure out why the voltage is too high. Any help on what culprit to lock for is appreciated.

Desktop/Near-field 5.1 Center Channel Speaker

I'm in a permanent WFH set-up, so I'm looking to "upgrade" a bit from the "plug into the headphone jack" powered speakers I've been using. The office is about 11" x 10", with the corner behind the desk cut-off. The computer has HDMI, DisplayPort and ThunderBolt ports, all of which can output 5.1 sound. I have an older Sony "Home Theater" amp that can take a couple of different 5.1 inputs (Optical and IIRC, HDMI). The setup will be used predominately for music, light gaming and me-myself-and-I movies watching.

I've done a moderate amount of searching, but I'm not really finding any "near-field" center channel pre-built or plans/DIY builds. At this point, the idea is to take an existing near-field/desktop plan, turn it on it's side, and expand the non-speaker enclosure potions to become a monitor stand/riser. Current contenders are the Zaph Audio Hi-Vi B3S single driver system, with the "near-field" cross-over tweaks and the Kirby Meets Audio Side-Fire Speakers, with the "side port" actually being on the top, behind the computer monitors.

That said, I'd rather not re-invent the wheel or use a fork to spread peanut butter, if there's better solutions out there already.

Hi
I bought from ebay a SRPP kit pream based on 6N3P.Please how can I reduce the gain because it is too high for my John Linsley Hood Amplifier.V+ is 200 V dc
thanks

Inspired by member henkel
http://www.diyaudio.com/forums/showthread.php?s=&threadid=64538
I want to ask those who know something about caps for signal coupling.

Do any of you have experience with silver mica in any applications where they perform better than film caps in the signal path?

I have heard that silver mica are the best for signal coupling, better than all the rest (all types of film or foil or paper in oil).
The problem is that they do not come in larger values than 0,1uF (100nF) and they are very expensive, and large!

So they are only a possibility in active filters and RIAA where you only need small capacitor values.

There are plenty of great music video out there but I particularly like animated ones, a guilty pleasure of mine. So what are your favorites ?

Some videos to get started:

Caravan Palace - Melancolia

Pearl Jam - Do the evolution

Daft Punk - Interstella 5555

Gorillaz - Feel good inc.

Modest Mouse - King Rat

Wolf Parade - Kissing the beehive (fan matching of the song to an existing movie, but amazing match)

I listen to music with a sennheiser HD600 headset connected to a lehmann amp clone. I'd like to try building a tube headphone amplifier. Can you suggest me some tried and tested scheme with an excellent sound?
Thank's
Dario

Starting a new post for this.

I have this tonearm on the way all being well.

To go on modded LP12 -
Mober one piece sub chassic, sub platter, DC motor, tranquility.
Going into a valve phono , pre and GEC KT88 main.
Feeding rebuilt Gale 401s updated with external crossovers plus an active sub.

The change in arm is so I can try a different cartridge.
I have recently being using a Shure V15 Vxmr / project 9cc which is good but I think there is more yet to extract.

The London decca super gold interests me although I know historically that divides opinion, maybe because of experience of earlier production.

There will also be MCs but to consider those I would have to find a suitable SUT at a good price.

I want to get those gales singing like a live event while not crossing into a fatiguing presentation that cannot do delicate also.

I know there are a lot of really hard core experienced computer folk on this forum which is why I am asking the question here.

Really pleased with my tiny Azulle BYTE 3 after I added a 500gb Samsung SSD which came with Windows 10 Pro. My last experience with Microsoft was Windows 8 - what a difference. I keep getting prompts to use Microsoft Edge.

Lots of really good and useful features with 10 Pro, so should I drop Chrome for Edge? I'd like to get some serious balanced advice before committing.

Hi All,


I’m hoping to get some guidance/clarification on how to mount a woofer to make impedance/TS measurements.


I have read many write-ups on how to make the measurements but many of these don’t even mention how the driver should be mounted. For the ones that do mention mounting, there seems to be several camps: 1) Hang the driver in free air, 2) Rigidly mount the driver in mid air, 3) Place the driver on the magnet facing upwards (but that doesn’t seem right at all).


Hanging the driver from the ceiling is the easiest and I tried that first. I was measuring a 2226 woofer and the Fs peak was at 50 Hz when it should have be 40 Hz. So I thought that maybe the hanging approach wasn’t right. So I made a fixture to mount the driver off the corner of a 4x4 column in the basement. The resonant peak was still at 50 Hz but there was now a peak at 34 Hz which turned out to be the resonant frequency of the 4x4 column.


The REW help files for making TS measurements states “Note that the drive unit must be rigidly supported during the measurements, and ideally mounted vertically.“ This falls into camp #2 but I have yet to find anything on how to do this.


So does one need to make an elaborate stand to mount a driver to take these measurements or can the driver be hung from the ceiling using a coat hanger?


Thanks in advance
Bob


PS. I have to keep reminding myself that this is to try and figure out why the 2226 FS is coming in at 50 vs 40 Hz. (“When you are up to your ears in alligators, its hard to remember that your initial initiative was to drain the swamp!”)


PPS. If the driver does need to be rigidly mounted, recommendations would be greatly appreciated.

Hello to all, I recently bought a C325BEE unit in full working order, but I was very disappointed with the midrange resolution and finesse.

It seems really strange to me, as I often read about complaints on the treble range, not in the middle.

I want to try a quasi-complete recap of the signal path, mica or polystirene capacitors instead of ceramic ones, new electrolytics (I like cerafine or Nichicon Muse) or substitution with polyester equal values and so on, if anyone is already experienced about this please can suggest something specific to me?

Anyway, having a look at the schematics sincerely I haven't understand what the rc cells R621 and C611 (see schematic attached) is useful to. It connect the two negative input of the stereo line amplifier.

I already seen this kind of topology (with bigger capacitor value) in a differential line amplifier based on two sections that works with balanced input signal. The RC constant of this RC cell suggest that it works form near-RF on (around 3,5 MHz), but:

• one has to be sure that both L & R cables are affected by the same type and amount of signal noise to cancel it as a common mode signal
• in the worst case, noise from one channel is injected to the other channel out of phase

It seems to me that it has nothing to do with stability, I'm just asking myself if it's necessary all at all, and sincerely I'd need a suggestion about it because I'm not a technician.

Just to give an element to think about, this RC cells disappear in the C326BEE schematics.

Thank you to all

What I sell is the following.
1. Dsc2 dac in its version for amanero and beaglebone. Attention, there is a channel that does not work, it must be repaired, I do not know exactly what the problem is or what part will have to be replaced.
2. Output transformer by Ivan Biselik.
3. "Super" amanero with improved Crystek cloks, regulators and separate feed, a wonder. (Modulo HIFI Italy amantero Combo384 USB DSD 512 / PCM 384 + Crystek CCHD 957|Kits de domotica| - AliExpress and Modulo de fuente de alimentacion LT3042 LT3045 para decodificador DAC, interfaz USB|Kits de domotica| - AliExpress)
4. Beaglebone green.

The set has cost me about 900 euros but as a DSC2 it has to be repaired I sell for € 500. Shipping costs borne by the buyer.

Hi. I'm interested in buying one or two of these tweeters if available. I'd like to have at least one spare before I start my build.
Many thanks to all.

Hi,

Does anyone know if there is a benefit to using off size capacitors to get a desired value for the purposes of a crossover?

Ex: Target is 80uF. Is it 'better' to use two 40uF versus a 20uF combined with a 60uF? Is there a simple rule, or calculation?

Thanks.

Hi Guys and Girls,

I recently bought this preamplifier as not working and with a little effort I had it back up and running. After putting it in rotation, I have to say I'm pretty impressed by this little preamp when I compared it with my Pass P1.7 and Decware Zen CSP. It does a whole lot right. However it does have one issue that I am hoping you could help me with. It has much more hum/noise than I would like or expect looking at the schematic. If I had very insensitive speakers I am sure this wouldn't be much of an issue, but my speakers are 98db/watt/meter and even a little noise can be very apparent.

I've attached the schematic, I don't see that this is copyrighted and considering it's no longer sold I hope it's ok to post. If not mods, please let me know and I can remove it.

Looking at this schematic can anyone tell me what might be able to be done to reduce the noise on this preamp? It looks like the first triode is setup for gain and the second as a buffer. Beyond that the powersupply looks pretty reasonable to me as a CRLC with a bypass film cap.

As an amateur, what are the thoughts on the following
1. snubbers on the rectifiers (with fast recovery I would think this isn't needed)
1b. There is a kind of digitalish noise as well as a very slight hum, could the problem be the regulator / DC filaments. The hum is louder but with my ear near the speaker I can hear the additional noise.
2. Something about the layout of the build is causing an issue
3. The upgraded caps take a up a lot of room, could they be a source of noise
4. The gain is set too high on the first triode
5. I am asking too much for a tube preamp to be dead silent. My Pass P1.7 is pretty much dead silent but that is SS.

What isn't shown on the schematic is that the rectifiers have been upgraded to fast recovery, the caps have been upgraded to hovland musicap (5uf I believe, which is higher than stock) and the original volume pot has been upgraded.

At this point I'm just looking for some directional information and possible things to try, any help would be greatly appreciated.

I bought these for a Borbely amplifier which I never got around to building.
2 each of 2SK216, 2SJ78. Attached is Id vs Vds $12 CONUS ONLY, shipping included.

I have a Heathkit IG-72 Audio Generator. It's been working pretty well for me, albeit the signal calibration was pretty sensitive. Recently it's stopped working all together. I either get a screwed up signal (see attached), or something that's so high voltage it looks like a square wave even at 50V on my scope (Most output frequency selection settings result in the square wave, a few low frequency settings give me the screwed up wave). When I get the square wave, the tungsten bulb goes bright.

I'm looking for suggestions on where to start. I don't want to start pulling and checking parts at random, and nothing *looks* obviously bad. Tapping on the voltage adjustment knob, or some of the parts connected to the tubes causes the waveform to jiggle, for what it's worth.

Happy to provide any additional information you might want to see 🙂

Hi Jan

I intend on using a subtractive crossover consisting of a 2nd order lowpass and a derived 1st order higpass with a Manger broadband driver and an Audio Technology woofer.

It could be woth a try since it is not very complicated and it is transient perfect.

Look at http://www.passlabs.com/pdf/phasecrx.pdf

Regards

Charles

I need to amplify a line-level signal in a piece of surplus equipment to a speaker level (1W) output. I have one of the Rainbow Kit amp boards which uses a TDA7052A chip. The amp is designed for an ungrounded output. Can I connect the (-) output line to chassis ground (headphone jack)?


Thanks!
Mike, WB0LDJ
mharmon at att dot net

Hi

I have the right channel OK et left channel blown.

I changed most transistors (2SC5200 and KSA1943 were short circuited) and diodes on the wrong channel but I still have this problem. On the D101 anode I have 2.5v between diode and ground without input signal and 65 v or more with signal.

I measure this value on the correct channel and it's always 1.1V on D101 anode whatever the input signal level.

I don't understand what is the function of the Q127 and Q137 transistors. I changed them but I replaced the Q127 with a 2SC3200GR, not a BL so the Hfe is different. Do you think it could be the problem ?

Regards

Eric

Hello everyone!


I have been looking into getting a new amplifier to play with. Mostly as a chance to swap my current class D amplifier in my desktop setup as well as using the building/soldering of the amplifier as some learning experience.


My current Class D amp is a TPA3116 with a 5532 Preamp.


I've been thinking about getting a LM3886 kit "on a budget", I have seen many great boards for this chip but I can't really afford them of now.


Doing some searches, Aliexpress does have some fairly interesting (looking...I know little about the 3886) kits, this is one of them:
Placa de amplificador de potencia unisian lm3886, amplificador operacional independente auido op07 ne5534 com protecao para alto falante 68w|Amplificador| - AliExpress


My question is, does anyone have any experience with those cheap kits?

Or, should I use my current budget (about 50 USD) to get another kit or components to build something?

Any recommendation or advice is much welcome, and just in case it serves the purpose, anything around 10 W or even less is good enough, as long as it can handle 8Ohms and have a fairly decent sound quality. Single rail PSUs up to 24V (I have a meanwell one) would be perfect, but I wouldn't mind needing to get a transformer, I should have a 13.5Vx2 laying around.

I've been looking in to building a SET OTL headphone amp and I want to use the tung sol 6SN7 for the voltage gain and Svetlana 6AS7 as power tubes. B+ is 200V right now but this can be adjusted I just don't want to face any huge issues with the 250V rating of the 6AS7's. the goal is to drive a pair of HD660s with ease and maybe even something with a lower impedance in the future.
I'm facing some issues with the simulation (orcad 2019) it seems like the coupling cap in the first stage is blocking pretty much everything I get roughly 5 uV swing after it even if I have a good 10v swing before it (which is still too high for the bias of the second stage).
Do you guys see any horrible misstakes made?
how can I improve it?
Do I need electrolytic coupling caps in the output stage as well or is it safe with only the poly ones?
also am I adding the negative feedback from the output the correct way, how can I increase it?
Lots of questions I'm still learning my ropes around these circuits.

That is in restorable condition. I don't care for the grill ,fabric etc.

I wanted to start this thread because I find that a lot of people aren't aware of the work that has been done in this area in the last five years or so. Much of this work is my own (our own) but there is also a lot of corroborating research - notably by Alex Voishvillo at JBL among others. I am best equiped to talk about my own so I won't specifically discuss others, but I am aware of it and it virtually all is saying the same thing.

In 2003 my partner and I published two papers on the perception of nonlinear distortion. Much of the results from this work is available here http://gedlee.com/distortion_perception.htm.

Basically through an ellaborate test of some 25 college students we were able to show that THD and IMD are meaningless measurements of distortion as far as perception is concerned. Basically one cannot say that something does or does not sound good based on these measurements. .01% can sound outrageous in some cases and 25% can be inaudible in others. The numbers are meaningless.

This result has been confirmed by several sources and now virtually eveyone in the loudspeaker business is coming to the conclusion that making THD measurements is pointless. Floyd Toole believes that nonlinearties in loudspeakers is irrelavent as evidenced by the fact that his new book contains no discussion of this topic. Lorri Fincham recently remarked at ALMA that THD and IMD were completely meaningless as a judge of sound quality. My own presentation from ALMA (China) last year says the same thing and maybe goes even a bit further.

Basically distortion, as we are used to thinking about it, is completely incorrect. This was further confirmed when we did a study of compression drivers published in JAES. In this study no one of about 30 subjects could hear nonlinear distortion up to the thermal limit of the driver - some 126 dB at the waveguide. This result was surprising and quite controversial, but it is holding firm as quite correct.

There are things that we perceive as distortion-like artifacts, but these are not nonlinearities in the drivers themselves, but are actually nonlinearities in our hearing system. This was brought to like by my partner and I in Oct. 2006 at the AES convention. These diffraction-like artifacts are perceived quite readily by us, but only at higher SPL levels, there are not audible at lower SPLs. These effects are virtually ignored in most loudspeaker designs.

All in all the situation is unfolding quite differently than what has been presumed to be the reality.

Recent studies of mine have clearly shown the human PREFERENCE for distortion of low order or at higher amplitudes. These are viewed subjectively as enriching the sound.

I am putting this topic out so that people can become aware of what is being recognized as the truth about distortion. Its not what we thought it was. Pursuing a loudspeaker design to lower the distortion is a waste of time if its nonlinear distortion that you are trying to lower. It simply doesn't matter.

Hello,
i'm doing a metal preamp that uses 12 vdc for heaters. So i used the 12V winding for the heaters with a diode bridge (4x1N4007). It works good.
But i used the 6.3V winding to give 6 vdc to the relays and the leds. I used a bridge that is 80 v 1.5 A and a 6 v voltage regulator (with 2 capacitors) and the bridge burnt after 2 secondes of no load at all, the relays were not connected.

Why?

Thanks

Hello, maybe someone has idea what those trim resistors might adjust on this preamp? Transistors or op amps?

I recently bought an old TA-5650 amp in very decent condition and am in the process of cleaning and servicing it.
The amp appears to be a letter model, with the changes made in the Dutch service bulletin and with the wire wrap power leads instead of connectors.
I have replaced the suicide diodes and installed the double diode centre ground in the voltage doubler circuit.
Yesterday I measured the V-Fets and noticed that one of the 2SK60s (number 6) was showing a little high on the SD measurement of around 3.5 ohms. Am I looking at a shagged V-fet here ? If so, does anyone know if there is any place to source a 2SK60 with JC-54 grading?

Cheers,
Jon

I bought the 3D model from Joseph Crowe and now it is being printed. One half finished, second one will be finished in a few hours. My good old Beyma CP385Nds will be measured on this horn. One half uses ca 130 m of PLA filament and with 0.3 mm layer and 20% infill it takes about 15 hours to print. The bottom part on the first piece is slightly warped, but that is no big deal, since the top part is flat for glueing. The second one will be printed most probably with more infill so that I will use one spool for both halves. And it maybe will bend a bit less with more infil. Woden CNC'd would look better, but if I ever have these made, they would be the larger ES-600 for 1.4" driver, I have Beyma 755Nd on my shopping list🙂

Hi!

Who here has mastered Soundeasy?

I use Dayton for measuring TS and impedance, I would like to input TS parameters in Soundeasy and start modelling a box. I have heard its a complicated program to learn but I bought it. I have looked into the Music and Design guide v4 but I have a newer version, some things are different and the guide starts with measuring TS parameters, but I would like to insert them manually. I tried but have no plots showing. I really want to learn this program, because it promises the best results but the info on the net is not enough for my brain. Maybe there is a way

I have been using Hornresp and WinISD and seem to understand them quite well, but now I need to model boxes as precisely as possible

A simple bassreflex box with a front port for start would be nice to understand how to model.

A

Hi,
Is there a diy amp kit at around 150$? quality is secondary.
Thanx,
Shirly

I haven't seen much comment lately on the results of the new Alpair 12P in various cabinets. In particular, I am wondering if anyone has had a chance to compare the new driver in the old and new pencils or perhaps the new driver in the older dbr or *ken designs.

Jp

Hi all
The above mentioned amp is dead. All fets looking good. The amp does not come on at all. Pin16 of 494 has around 11v.

594 is having oscillations.

Moin! (Means hello in northern germany)

I try to build an class AB push pull tube amp with KT150.
But it only workes in Class A. If the Power is going higher than 1W, the sinus is collapsing.Any suggestion what can be wrong?

The power source can spend 1.2 A and the actual consumption is ~ 160mA.
The is no disturbance of the gate signals of the KT150.

Greetings Kai

V1 is well underway - that's my personal headphone amp for my mancave.

I'm now looking for a small 20W stereo amp to drive some full range smaller Markaudio speakers. Footprint size, square and 12" corner to corner (realistically 10") to sit in the living room under the TV on an open shelf. Basically this is for the mrs to listen to Adelle in the front room on the CD/Bluray player. If possible the supply in the same box, but option for a small external supply box exists.

I was thinking of a small SRPP with a solid state backend - perhaps a small class D backend fed by a SRPP buffer (the recent thread got me thinking).

Has anyone done any projects like this?

Perhaps something like this: Hybrid Amplifier by Andrea Ciuffoli but scaled down from 100W.

Crystal CS8412. Seems to be a pulled one from an IC socket. I don't remember why it was pulled but I sure don't stock defective stuff so it must be OK.

For those that have those nice jittery Audio Note DACs a spare SPDIF receiver 🙂

10 Euro ex shipping.

Would love for some wiser & more experienced folks to chime in on this project, as I've been going back and forth on driver choices and design decisions as I wait for the SEOS 18 1.4" horns to arrive from Autotech, a slight roadblock at this stage.

This build is intended for moderate listening levels (hi-fi) 90% of the time but needs to be able to withstand PA level territory (115dBA-120dBA) as the multi-purpose space might host the occasional DJ set. A total of 4x 2-way cabinets in a 80ft x 25ft room with 2x Danley TH118 on sub duties.



My two questions aim at finalizing design choices on a no compromise high-efficiency 2-way with a big (14 or 15"), low-mms woofer with great midrange & break-up behaviour + a 1.4" CD that is a great fit for the SEOS 18-1.4 and it's dispersion characteristics for an xo between around 650-950hz (more on this below)

-System is active (BLU 160, FIR filtered)
-2x Danley TH118 on sub duties
-cabinet volume limitation around 75L-100L (port layout based on Altec 9812)

I was originally set on using 4x JBL 2226H I have on hand (and for which I built a test cabinet with good results). But I had a bad surprise when I ran measurements on all 4x units: only 2x have original cones, the other two have been reconed with what appears to be aftermarket cones. Here is the test cabinet and FR/Impedance plots.



Since the JBL is old tech that clashed with the rest of the components anyway, I went back to the drawing board & set out on a search for modern 15s that fit the bill. But before committing to anything, I want to measure the SEOS 18 1.4. I'm basically hesitant to commit to other aspects of the build before I can fact-check my design decisions with measurements of the horn.

Tell me if I'm over-thinking it, but here's my reasoning:

Since the polar plot of the SEOS 18-1.4 is inexistant online and unavailable from Autotech, here is the plot of the SEOS 18, the closest relative to the SEOS 18-1.4 for which there are polars available. From my interpretation of the polar plot, it seems the dispersion is effectively closer to 70°h x 80°v between 650hz and 900hz?



I'm concerned that my dispersion measurements of the SEOS 18 1.4 turn out to suggest a higher xo than what I originally had in mind based on the SEOS 18 plots above.

If the pattern control at 750hz is marginally better than in the SEOS 18, could it mean the dispersion no longer matches the 15's narrowing dispersion at 750hz, or would that be a negligible difference? Seems like I could be looking at an ideal xo point closer higher than originally planned.

Alternatively, would you consider this a good setup for the DCX 464, with a 500hz-650hz xo? This would mean I'd have to use the horn below it's pattern control cutoff. The consequences of this seem negligible vs. achieving a directivity match at the crossover point. Thoughts?

If there's a possibility to cross lower by using the DCX 464 instead, it would mean i'm no longer bound to using a mid woofer clean to 3khz and can be looking at more midbass oriented woofers. I'm also unsure of the consequences of crossing this low on that horn, aside from the pattern control loss. Anything else I might be overlooking?

Considering I don't need much output below 70hz from these cabinets as they will be used with 2x TH118s, would you stick with the initial plan that called for a woofer with good midrange performance well into 2Khz territory?

Do any of you see any issue with the reasoning of a capable mid woofer vs. more midbass oriented alternatives? I don't see much benefit from the latter when used with quality subs, aside from the ability to play louder for longer. B&C 15NDL76 can handle the occasional abuse from my experience. What about the Faital 15PR400? Xmech is rather low. It also seems to want a cabinet around 150L (like the Calpamos for instance) I'm wondering if that's as good a candidate as I'm hoping.

Here are my woofer options if ever some of you strongly favour one over another:

If horn dictates xo around 650hz to 900hz:
-Faital 15PR400 (wants more volume than 100L, any succesful builds in less volume?)
-18Sound 15MB1000 (hard to get)
-B&C 15NDL76
-B&C 14NDL76 (could 14" be wise? possibly a better dispersion match)


If xo can be lower (500hz to 650hz):
-Faital 15FH520
-B&C 15NW76
-B&C 14NDL88 (14"...)


Am I making a mistake discarding the DCX464 based on the 800hz cutoff of the horn?

What would be your preferred approach for the compromises presented above?

Hi all,

I am looking for ideas for a DIY high SPL speech system to be deployed outdoor for political rallies with crowds of 3000 to 6000 people.

What are you using?
What do you recommend?

Just bought a pair of these for events with no power. Play music from a USB stick, tracks are numbered but speaker plays in random order. How can I set up to play in the order on the stick ??

Very beginning:

4 G subs loaded with RCF L18P300

2 Mackie SRM550

Upgrades:
Either addition of 3 Cubo Kick 15 loaded with Kappa Pro 15A

OR

2 G subs become kick bins, drivers from the other 2 G subs are used in 4 Paraflex C2E 1x18"

The G subs are a very simple build with decent output, with 8 of them lined up will be sure to provide the sub and kick to begin with.
The Mackie SRM550 are a bit more budget friendly high output mid top that should last for a decent while, while having good clarity.
Deciding how to upgrade will most likely depend on budget/what the future of the system would become. If it stays more local and smaller, the Cubo Kick will be the go to upgrade (as it stands right now) and if the soundsystem will see bigger venues and bigger events then the paraflex will be eventual upgrade.



Will mostly be used at the start for upto around 200 person gigs outdoors, and upto around 300 indoors, focussed mostly on jungle and drum and bass.



Any feedback on anything within here would be helpful. Recommendations for alternative designs for subs or alternative tops would be appreciated 🙂

Hi,

JBL Nano K8 vs JBL308PMKII: Same woofer size, same waveguide size, both active crossover biamp systems. Functionally they seem to be identical, whats the difference? I dont get it.

JBL NANO K8 | JBL Professional Loudspeakers
https://www.amazon.com/JBL-Professional-Next-Generation-Powered-308PMKII/dp/B077NHM2K6?th=1


Thanks and Regards,
WonderfulAudio

Need a little help , I have a near mint au9500 in bench . Everything is original and fully working but not the loudness.
The original volume pot was replace for a modern blue alps . This has no tap for loudness so the wire from pcb have been isolate .
Now I like to have it again ,. I don’t mind if loudness depend on volume pot position . Just switch loudness .
I have tried with 3 resistor value 3/10/47 K.
First I solder the resistor from tap wire link to the middle of pot . No difference
Then from tap link to ground.... no difference .
I think need two resistor one from input of pot to tap and another from tap to ground .
Someone can help me or maybe already had experience.
Just a little and show schematic part

Was reading Merlin's HiFi Preamp book, he talks about the golden ratio and 1/3 Imax with 2/3 of B+ (or HT).

Since ra is roughly 3k in a 6922.
(My B+ is 250V):

Ra should be 2xra.. so 6k. Isnt it too low?
Imax then would be 41.6mA.

And center bias would be.. 2/3 of B+ = 167V ; Imax/3 = 13.8 mA.

Is this correct?
How should I choose proper plate resistor?
Thanks.

Hello,

I want to make a portable DAC+headphone amp. Powered by mains, but not huge and heavy like my normal DAC with tube output and OTL headphone amp.

On the other hand, I want to get the best out of it what I can.

I stick to the AD1865 in NOS config, and TPA6120 at the end. What is in between is new to me again. Last time I've used opamps was lots of years ago.

I would appreciate if you would look at it and tell me if you have concerns if it works, or, how would you improve it.

Thanks a lot,
JG

View attachment sch.pdf

A friend asked me to fix her Toa model KD-1 integrated combo amp. She plays Cello in a local quintet.
This unit has one mic input, four RCA type inputs an amp, and a 12" speaker with a secondary small cone (forgot what hey are called) attached to the same voice coil. TOA had a good rep back in the day,
Anyway, the power amp is bad and it has one of those dreaded (IMO) STK modules which is a complete audio amp in an lage hybrid IC package.
I've only heard how unreliable these modules are. I suspect the run away thermally?
It has the STK 3046V. specifically which doesn't seem to be available.
What's the scoop on these things. There appears to be many variants. Do they all have the same pinout?
Should I attempt replacing with a different variant.?
If I owned it, I'd replace the module with a class D amp I suppose. I'm not willing to put that much time in someone I'm working on for free for though.

I am selling a pair of magnificent Fullrange Tang Band W8-1808 speakers. Only drivers does not include the wooden stand in the photo. Used few months in Open Baffle project. Great sound.
Your price 450 euros plus shipping from Spain.
I do not have original packaging but I do have a plastic protector and they would be sent in suitable packaging.

I have a pair of Infinity 2.6 active speakers in good condition, except that one BASH amp for a woofer is not working. Am willing to part them out, sell both as-is ($300), or purchase a working speaker or internal amp crossover so that there will be a working pair of these good speakers for someone.
Let me know if you wish to buy or sell parts or complete speakers.
Thanks for having a look.

I think these are the holes to drill out to install the front panel handles (however hear them referred to as the LED pilot holes). There are some similar holes that are hidden under the installed heatsinks. Is one set intended for the handled?

Here?


Or the ones under the heatsinks?

Can someone tell me where I can find these? I want to try these tubes...

Our lounge room is our listening room and has a few of the normal problems associated with small rooms that are square.
Room is 4 * 4 and 2.7 high.
I'd like to put something on the wall to help a bit with HF bounce and I need to have some convincing arguments when having the discussion with SWMBO.
I was thinking of a single layer of something very heavy like 40kg felt or double thickness carpet but The Boss may prefer something diaphanous. Is a double layer with the LW net on the front coupled with something more solid closer to the wall more effective?
My beloved is highly resistant to me going back to hanging old woollen blankets.
On that note how effective are floor rugs as wall hangings?
The wall hanging would be about the size of a medium sized rug, say about 1500/1800 * 2700 / 3200mm
No need for it to hang lower than the back of the lounge or the chairs IMO

Hello!

I'd like to build a JFET buffer to be used either as an input buffer for a power amplifier or for S&K filters for electronic crossovers (similarly to the LX Mini crossover by Nelson Pass). I can't decide between two topologies.

On the left, a JFET buffer designed by Arthur J. Metz in the '80s for Tek 'scopes (US Pat # 4,471,319) and modified to use N channel JFETs; on the right the input buffer of the Pioneer A09 Class A amplifier (authour unknown), modified to use available JFETs.

I plan to use LSK170 and LSJ74 JFETs for the input device(s) and J112 and J270 for the cascodes (the only reasonably complementary pair with an available P channel JFET amplifier - not switch - I've found; suggestions for alternative parts are welcome).

I'd like to hear expert opinions about the two topologies (beside the obvious disadvantage of the need for P channel JFETs for the Pioneer). Suggestions for alternative topologies are welcome but the complexity shall not exceed the Tek circuit and part selection shall not exceed the requirements of the Pioneer circuit.

Thank you.


Giorgio

Hi Guys,

Just looking for some help with the power supply requirements on a LM1875 based amp im trying to plan. Currently my plan is to use a unipolar supply biased. I've come up with the below and i was wondering if I was correct or if i was just confusing myself.

Audio Signal Voltage : 0.775vRMS
Speaker / Load Resistance: 8 ohm
Efficiency Assumption: 50%
Continuous Power: 5w

Am I on the right track in saying to achieve 5w @ 8 ohms with a 50% efficient amplifier i would require a 36v supply which would source just under 1 amp of current to avoid it from clipping?

I also know that the LM1875 needs a closed loop gain of 10x to stay stable, but I can attenuate before the amplifier to reduce in input signal to achieve a power target.

Hello all. I have a bunch of old vacuum tubes and I was wondering if there are any circuits that use simple tubes (preferably AA5 tubes like 12BA6, 12BE6, etc) as a sort of buffer to add tube-like timbres and tones to an input audio signal. I am not an expert when it comes to working with tubes (I generally try to avoid it when possible) so any help is appreciated. Thanks

So this amp has B31n20's and IRF9640's in the output stage.

Anyone have any history with alternates? I know I can get B38N20's, but what to use for the 9640's?

Also, 3205's acceptable in the PS?

Since I am self-financing my research and development, time to time I sell finished prototypes that I build to test new features. Here is one more for sale.

2021 prototype Edelweiss-3 Power Amp Plus vacuum tube | eBay

Has anyone ever tried to make a discrete copy of buf03 or even sim it? The circuit looks very unique to my untrained eyes. Probably lent a single ended sound which is part of why the chip is held in high reputation to this day. And its uniqueness alone could be of great value in this day when theres one too many diamond buffers floating about.

Attached is the most detailed schematic i could find. Id be happy to breadboard it if the missing details could be figured out.

Howdy y'all.

been searching the japanese sites recently. a simple google for yourself will do the topic justice.

apparently, the FE138ES-R in a 5 inch swan style enclosure is recommended.

start drooling. I hope they make enough to satisfy the global market this time. so put pressure on them.

they will likely not be super expensive. I would estimate them at about a grand usd a pair. or thereabouts.

hi guys!

i'd like to bi-amp my 3-way speakers. to do it properly, i need an active crossover. The passive crossover crosses at 300, and 3500 hertz. It is my intention to use an active crossover at 300 hertz, and keep the passive one at 3500 hertz.
does anyone of you have experience with a variable crossover as used in the world of PA? Is it a bad thing that the passive crossover in my speakers is of a 4th- or 3th-order, and that most active crossovers are 1st-order?
any help would be appreciated!

keyser

Hello,
I have a Hypex UCD400ST that is about 12 years old, and I haven't used it in the past couple of years, but pulled it out, and it is having some problems. At low volume it works, but once it gets only slightly loud it cuts out and resets continiously. I put a meter on the VIN, and it doesn't seem to cut out, so I guess it is the amp itself. Any ideas on what I can check? I don't have a scope, but just meters.

Thanks.

I'm looking at parts to build a dummy load. I am considering using one of these 100W resistors: Acl Ap101 | Ohmite Mfg Co

I identified this heatsink: Sink F R | Ohmite Mfg Co

Based on a figure of 3.5W at 25C.

I have a hard time understanding how to match up parts and heatsinks, which is why I'm posting here. If I'm off track, could someone people explain the process for selecting a heatsink for a given part? When I google, I find mostly stuff about designing custom heatsinks.

Actually the title may be misleading - I don't need help screwing up my SP-10, I've done that myself.

I bought an SP10 that didn't have a PSU. I built a PSU according to the design by MP Barney. It's a clever design that starts the 32.5VDC a bit later than the 5V owing to a larger capacitor on the 32V regulator. I've built one of these previously and it worked like a charm.

HOWEVER, I'm an idiot: I connected the 32.5V supply to the 5V connector on the table, and vice versa. I corrected it but the table won't run. I suspect I've screwed up the logic circuit by supplying it with 32V instead of 5V.

I don't have the slightest idea where to start troubleshooting. Any suggestions will be appreciated.

EVEN BETTER would be someone who would do the repair for me. Of course I'd pay the going rate for this work. If you're willing to tackle this, please drop me a PM or email at whirsch@indy.rr.com

Thank you.

I am refreshing an ADCOM GDA-600 DAC as a learning experience and trying to understand some of the LPF used here.

This DAC uses dual channel op-amps per channel. To my understanding, each opamp does both I/V and filtering.

I've attached the relevant section of the schematic.

A few questions:
1) Is it correct that this is a "second order LPF" ?

2) There is an LC filter on the output. Is this actually needed given that we already have active filtering?

3) Can the circuit be optimized here? The cap values here seem to be non-standard based on Digikey and Mouser inventory. I've also read somewhere that the resistor value should be between 10K-100K while 1.21K is used here.

Thanks!

P.S I will be replacing the stock op-amps with OPA2132 if that matters

Hello. According to Fostex literature, the 3" satellites in this system are full range. Why is there a Crossover? network on the speaker terminal cup?

Hi All.

Aleph L first revision without switches is giving too much gain. Hardly possible to listen, its playing with original pair of Aleph 0 monos. Even on the second pot position it's almost too loud. Friend of mine bought it used from Japan. Surprisingly no dip switches onboard. (see pictures).

Any schematic available for this particular revision? Nominal values are of the most interest. Board picture is attached.

hi i bought a damaged crest 4001 amplifier



im new to repairing amps i have repaired already half a dozen

but this is my first profesional amp

so i already changed the damaged nec 2sb600/2sd555 https://www.diyaudio.com/forums/attachments/solid-state/998278d1637121923-crest-audio-4001-profesional-poer-amplifier-help-biasing-help-datasheet-2sb600-2sd555-nec-pdf outputs transistors for on-semi mj21195/mj21196 https://www.diyaudio.com/forums/attachments/solid-state/998279d1637121923-crest-audio-4001-profesional-poer-amplifier-help-biasing-help-datasheet-mj21195_on-pdf
changed all the capacitors, some damaged resistors, diodes, the damaged toshiba drivers 2sa10006/2sc2336 https://www.diyaudio.com/forums/attachments/solid-state/998280d1637121923-crest-audio-4001-profesional-poer-amplifier-help-biasing-help-datasheet-2sa1006-1006a-2sc2336-2336a-2336b-pdf for on-semi mje15032/mje15033 https://www.diyaudio.com/forums/attachments/solid-state/998281d1637121923-crest-audio-4001-profesional-poer-amplifier-help-biasing-help-datasheet-mje15032-pdf and a damaged mje340https://www.diyaudio.com/forums/attachments/solid-state/998282d1637121923-crest-audio-4001-profesional-poer-amplifier-help-biasing-help-datasheet-mje340-pdf for a new of the same

the amp is turning on the 3 relays click and i have output the thing is the biasing preset is turn all the way down its a 250ohm preset its my first to-3 transistor amp i fix and i cant place the probes easily as a to-222 transistor because of its design and i need help so where i can place the probes to calibrate bias and if i need to put a higer ohm preset

A boring question but needed---

I find soldering a pair of wires to tiny microphone capsules to be a daunting task. I tried both lead and silver and while I am succeeding it is slow and I overheated a few capsules.
Short of cutting PCB boards to mount these does anyone know if there exists, a socket to receive the common lead spacings of small capsules?

Thanks
Fritz

I received this amp for repair.. Obviously everything is OK. It started for a few seconds, than in protect. Checked the audio banks, one works good, the other has problems to build up waveforms. I don't now this drive board. Is there also irs21844s inside? Mosfets measures all OK. The output from the drive board is buffered.

Wondered if anyone had one before I purchase a new kit?

Ideally 230v, but can convert…

Gavin
Oxford,UK

My AC main voltage seems to have crept up quite a bit. We used to get ~225V AC a few years back, and now it is around 240V-245V AC.

Given the situation, I am thinking of installing an AVR (Automatic Voltage Regulator).

There are various types - which ones are good for audio?

I have posted on the solid state forum as I intend to run solid state gear on the AVR regulated mains. If the moderators think this thread should be part of another sub-forum, please move it there.

Hi, for sale 2 Fostex T90A. With very little use (50 hours approximately) and Attenuator (L-Pad) Fostex R80B (two units). Gift 2 capacitors of 0.47Uf necessary for connection. I send photos to those interested.

Shipping only to EU, shipping costs borne by the buyer. Price for everything 500 euros non-negotiable, if I sell separately 450 euros the couple of Fostex and 60 euros the couple of R80B.

Best regards

My 1700B won't null intermittently, lightly tap the front near the "distortion" push button and it will null. I have verified the oscillator is OK. So my question is has anyone ignored the warning stickers inside and cleaned the switches with DeOxit?

Craig

Hi everyone. I’ve been building a high end PA system in the past few weeks. Ultimately it’s more or less a copy of the pm90 but using bigger driver. Instead of the 12 inch woofer I’m using 2 15 inch B&c 15nw76. I’ve also decided to use a bms 4599he coupled with 4 ciare ct440 super tweeters. I’m still waiting on my bms 4599he as it’s being build, but almost everything is done except for a few touches. I have been contemplating a few ways on how to mount the 4 super tweeters. Given the limited space I have left, I was thinking of just mounting them one on top of they other. The only problem I’m running into is, coverage. Ciare has not shown it’s of axis response nor its coverage pattern. So coverage might be limited if it’s all on the same horizontal axis. On a side note, I’ve built a 90x40 horn for the bms 4599he. So ultimately I would want the coverage pattern on the tweeter to be quite similar. Any suggestions? Additionally, I’m not exactly sure of the built quality of my horn for the bms4599he. The horn sensitivity is obviously a big concern as it’s meant for pro applications. It also need to be able to play at least down to 650hz where it will be crossing with the 15inch woofer. Any suggestions would be much appreciated. Thx

Hello,

I've built a player (or several before 🙂 with RPI+moOde >> I2S FIFO >> serial convert >> AD1865 >> I/V trafo >> ECC82. That is my main DAC, but now I need one for headphone music listening. I would use an XMOS / Amanero USB >> I2S board than an I2S DAC.

If I like AD1865 the most, what modern DAC would I like now? AK or ES ? Which version?

As far as DAC chip, which is the best nowadays for mainly acoustic music?

I have a Chinese AK4497 board what I do not like. I guess it is the opamp output, but It is rather harsh. I do not like to wash away details, but for me, quality comes when it sounds pleasant and detailing in the same time. Of course, it could be that the DAC chip is just a copy also, so I do not judge based on this, but I need help which DAC should I go with?

Thanks a lot!
JG

Hi All,

About 15 years ago my father and I built a pair of cabinets using FE206E drivers. I'm almost certain these are the design plans, even though the driver listed is FE206EN.

https://www.fostexinternational.com/docs/speaker_components/pdf/FE206En.pdf

The drivers have seen better days so I'd like to replace them.

Should I replace them with the Foster FE206E, or are there better options now?

Advice on amplifier choice is welcome as well-I've always wanted to build a tube amp for them but haven't gotten around to it...yet!

Good evening everyone. I thought I would share pictures between the two Fostex Fe EN vs the Fe NV driver’s. I have not heard the new Fostex FE126NV drivers next to the FE126EN drivers which are one of my favorites. So I will be doing a project with the New NV drivers soon. So here is my take on each driver Just looking at them both side by side.

Fostex FE126EN Driver’s.
1. Has a bigger magnet.
2. The cone is almost very light and almost see through.
3. Heavier.
4. Nice live sounding.
5. You get more Info on the drivers Mechanical specs and small parameters.
6. Has been around a while.

Fostex FE126NV driver’s.
1. Cleaner wire hiding and no white dots on the cone from soldering.
2. The magnet is not so big and is more rounded even.
3. Gold plated terminal’s and are spaced out a little more from each other.
4. Frame is more of a glossy black and not a coated black finish.
5. The cone looks cleaner around the edges and the middle dust cap.
6. The cone looks more stiffer and has sparkling on the cone? Fairly dust 😀
7. Shipping with a plastic speaker cone protector.


Things I don’t care for in each driver.
1.Still has a steal frame and can cause a problem if you don’t dampen it some how.
2. Magnet is either to big or small nothing In the middle or a different type of magnet material.
3. NV has very little info on published driver Info like T.S.
4.FE has a sloppy look to around the dust cap and outer edge of the cloth sound.
5. Charges a lot for the drivers.


This is all I can think of. Again I will be working on a project soon with the new drivers and I will post pictures and give my honest opinion. Cheers Jeff

I have amp with Hypex Soft start and Hypex SMPS1200A100 psu. Amp is about 1 month old. Amp was in old box. Yesterday I transferred everything in to nice new Modushop box. When all done, I did a power up check before putting the top cover on the box. All was good. Cover on to box.

So, this morning I'm all excited about the amp in the new box and everything all nice, neat and tidy inside and outside the box. So what happens .........amp does not turn on.

Off goes the cover, turn on amp and I see the Power LED's on the just flash on and off. So something not working right.

Voltage checks show soft start is good. Hypex psu voltage is not good, at +7V and -1.2mV for rail voltages.

SO, is there something simple and fixable on the psu?
Or is the psu stuffed?

I'm just throwing this out there in case this has happened to someone else and perhaps there is some easy answer other than "Get a new one".

Have the below terminals at this mount
NCJ9FI-S | Neutrik

1, 2, 3, G, N, RN, T, TN, S, SN

How to make the wiring connetion in this?

I have 8 channel snake cable.

DA2X - 220V version
DA202 - 100V version
No repair and no modification before. Original working set.

Please offer me and work out a total including shipping method and cost.

Regards, Spencer

I have for sale one (1+ 1) Seas Nextel W18NX001 unit. Unit was lightly used for few years and it is in perfect mechanical and electrical shape. The metal plug is nickel chrome polished (new versions has a bit different finish). Original packing included.


Price is 90 EUR + post costs. Payment via PP.