Can an advertisement that has been placed have the title modified? Can the advertisement be removed? Thanks

Hello,
This is my first thread here so please forgive any mistakes. English is not my native language.

I started building a DC blocker for my AV set-up devices: Pioneer VS-LX305 multi-channel amplifier in a 7.1.2 speaker configuration, Panasonic HD DP-UB424 BD Player + a few smaller components.
When building a DC blocker, I wanted to use a ready-made solution. No, not high-end because I don't expect a miraculous improvement in sound😉 I just want to proactively protect the equipment from a possible DC component so I bought a medium-sized module on Aliexpress. The schematic was not included, I drew it in LTspice:



Question #1:
What do you think about such a DC blocker? It seems a bit oversized or maybe even exaggerated, but it is built rather classically.

The total capacity is 9900uF and consists of 12 pieces 3300uF/10V capacitors connected in opposition (as bipolar). I want to believe that the Nichicon print on the capacitors means real Nichicon and not "clones"😉

I have doubts about the huge number of diode bridges. There are 6 bridges (KBJ2510 1000V / 25A), which means there are 24 diodes in the system. Please correct me if I'm wrong: diodes connected in this way will limit the maximum reverse voltage on the capacitor pairs to a maximum of 2.5-3V. In my opinion, this means that the reverse voltage on a single capacitor will be 1.25-1.5V. It seems to me that this is a bit too much. I would prefer to stick to the maximum reverse voltage of 1V on a single capacitor.
On the other hand, diodes connected in this way ensure blocking of the DC component to 3V. In my home installation, I absolutely do not expect such a high DC component, so the value of 3V in my case is oversized.

Question #2:
Would removing two bridges with diodes D17.. D24 be a reasonable move? What do you think? This would reduce the reverse voltage on the capacitor pairs to a maximum of 2V. Of course, the DC component in the home network would then be blocked to 2V and not 3V.

I would be happy to hear all opinions on the subject I have raised 🙂

thinking of one thing.. for those of you who have backup units, won't these degrade over time when they are stored? thinking of capacitors and belts for example

All 6 woofers perfect working order- pickup 44405 $75 for all 6



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It's 10" manufactured by Samco (I've no idea who for). It looks very Technics or Pioneer, possibly Aiwa.

hello. I have a nice specimen here that is blowing the mains fuse. would anybody consider taking a look for a reasonable fee and or taking the amp and using it for a while?
thank you.
I'm in maine
tom

I'm considering building this offset TL, which is slightly big for the 12" driver I'm planning to use with it (an Eminence Kappalite 12" 4 ohm driver). The predicted output looks like it's going to be better than a TL that I built using the same driver, for a slightly larger cabinet. 120dB all the way down to 40 Hz, with 40V input, and not exceeding Xmax. I want to test a little "theory" of mine - that ensuring that the vent is the same or larger CSA than the driver's Sd produces audibly better results than a simple vented box where the vent's CSA is significantly less than Sd.

Shown are two full crossovers, labeled A and B, with their differences shaded in color highlighting (orange, pink, yellow, blue, green). Each crossover was designed for identical LF, MF, and HF drivers except the HF driver in B has ferrofluid (ie., the HF driver in A does not have ferrofluid).

QUESTION: Can you identify what function each of the color shaded legs are meant to provide? (E.g., the yellow leg appears to be a notch filter in the LF driver's low pass filter...it may be there to alter impedence and/or attenuate some portion of the spectrum that's passed to the LF driver.)


BONUS QUESTION: Both A and B were production crossovers. What two loudspeakers were they used in?

I have a schematic for a 20 watt battery powered guitar amplifier. What steps do I take to get to the PCB stage?

I am not electronically inclined. To me electricity is "PFM" Pure F..ing Magic. So some directions would be helpful

I built the ProtoDAC. Everything assembled fine using a 65watt power supply, PurePi II, RPi5 8Gig. I have a question or two about implementation. It seems that I bought a RPi5 and Mo0de doesn't yet support it. I would feel bad posting this question on the Mo0de site. Picoreplayer and Volumio don't have an output selection for the Protodac. I have gotten the DAC to play using pCP using RPi driver. But the output is very slow like playing a 45RPM record at 33RPM. Any insight you anyone might have with the output configuration would be helpful.

Using a Hammond 278CX 800VCT 535mA. Starts to vibrate at about 75% of full primary voltage. Looking for other designs but not finding. NEED Something potted or maybe toroidal. HELP.

I will propose this modification of the output stage. Up to 9 watts operates in class A, is not sensitive to low-impedance loads, the output transistors operate without thermal overheating, the circuit characteristics are stable, the operating point is also more stable, the distortion spectrum up to 10 watts consists of only one second harmonic, closer to the maximum output power it increases slightly "tail" of even harmonics,
sine wave limitation is symmetrical.
with a power greater than 9 watts, the output stage operates in class AB with symmetrical (not to be confused with complementary) control.

This modification allows you to unload the current of the driver transistor Q9, and make its operation less dependent on the complex load impedance, i.e. Q9 began to work in a more linear mode than in the original version. Also, the output transistors received symmetrical control of the base current. with a power greater than 9 watts, the input stage operates in class AB with symmetrical (not to be confused with complementary) control.
compensation capacitor C8 appeared due to the fact that the input capacitances of oldschool slow/slow transistors no longer affect the frequency parameters of the driver transistor Q9.
Q9 received freedom !!!)))
The depth of negative feedback increased by 7dB and remained the same linear as in the original circuit.

Hi everybody. I've read hundreds of pages already on the diyaudio forum but never registered. I'm neither an electrical engineer nor an audio builder, at maximum I could say that I can assemble something if it's easy enough.
I already have a dual a Hypex NC400 amplifier but I'm looking to build a Nilai amplifier the coming period, so see you around.

SOLD
Miro PCM1704 DAC board for sale. This board allows JLSounds i2soverUSB or York with reclocking to be stacked for a nice, direct interfacing.
There is no IV stage on this board. You will need to improvise your own IV stage.
Two pieces of PCM1704 J graded chips on the board.
*Important Note : These are recycled chips, which were removed carefully with proper heat control. They work perfectly. I do not source the chips from random Ali or Ebay. They are from a reputable source.

What you need to provide :
1. You will need to give it PSU with rails +/-5V (Analog) and +/-5V (Digital).
Optional - one +5V for the 'dirty side' of the USB interface if you do not want to have the USB part powered from the USB bus of your PC source.

2. i2s source - JLSounds i2soverUSB or York + Reclock is needed to feed it in order to play music. Both JLSounds or York have the mounting footprint to be able stack nicely on the DAC board
http://jlsounds.com/i2soverusbFIO.html

3. IV stage of your own - tubes, discrete SS stages, transformers .....
4. Chassis, wires, connectors etc

Board fully populated with good quality components.

DAC board + shipping registered & tracking = USD 165

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

never used 3 watt stereo amp..
I had this too long.
cleaning house.
sold as is . may need new caps
usa sales only
$30 F&F pay pal plus shipping
$40 if you need invoice.. plus shipping
ship from 45385.. 2pds 8 oz 12 x 8 x 6 box usps
thanks
Doug

Up for sale is a 4pcs set of Tokin 2sk180 (2 matched pair)

They are matched at around 24V @1 amp, Vgs -3.62, -3.6, -2.5, -2.24
This is my last quad for sale.

Asking $225 +shipping.

Hi, I’m building a power supply for an audio amplifier and I need help with figuring out which manufacturers, and the options to pick?
I want to use quality parts so I’m looking for what you guys would pick if you were building an amplifier for your self. I’m learning as I go and have a couple books, but I haven’t come across how to pick out a good transformer?
It would be for a 350 watt stereo amplifier so it would be able to drive any speakers I might use in the future.

My aim is to have subwoofers which will work with different rooms, usually small ones (I rent, and move home reasonably often). Room modes are therefore unknown and going to vary; the best way that I know of to counter this is flexibility of subwoofer positioning. I don't need to cover a huge listening position, but reasonable evenness is still desirable so multiple subwoofers are preferred - I shall aim for three or four. For both reasons, and to help when moving home, small size is wanted; I'd like to be building something more exciting, or at least dual-opposed (push-push), but for now have settled on single drivers in simple sealed boxes as the practical answer.

My drivers are the 12" FAB12 4ohm version from BK electronics (much like the famous LAB12, designed for large horns but also at home both vented and sealed).

One reason for going with sealed is to eliminate ports/vents; again largely for size but also to avoid having to deal with possible port noises. One down-side of distributed subs are if they make spurious noises, that can become audibly locatable. I've also no need for a resonant alignment to increase SPL as my goals there are fairly modest.

These subs are for music, rather than home theater, so in order to keep size/weight/cost reasonable I'm not going to aim for THX reference levels or super low frequencies. I'd be happy with 85dB + 15dB peaks = 100dB max at the listening position, down to below 30hz. IMO that is quite loud in a small space; it is often accepted that target SPLs should be reduced in such situations (I've even seen as low as 76dB + peaks considered appropriate for control rooms), so 85dB + 15dB is fine for me. The listening distance is 3m so as a worst case (except for room modes) I'd only need to achieve 110dB at 1m within Xmax.

Here is a WinISD simulation of one FAB12 in a sealed box. In this case it has a Linkwitz Transform to Q=0.5, with high-pass to restrain LF excursion and an 80hz low pass (my intended crossover). It reaches Xmax at about 20hz, with about 106dB output and still only -3dB at 27hz.

A pair of these should at worst gain +3dB, realistically in room I would expect at least +4dB so there is my 110dB, even without the third or fourth subwoofer. This is why I don't feel that I need a resonant alignment for my situation. The multiple subs are for smoothing but do add a little SPL as well.

5 years since I last asked - has anyone tried them?

I decided I wanted to replace the very heavy 8-channel SpeakerCraft BB865 Class A/B 8-channel amplifier I use to drive some active 3-way stand mounts in my office. There were no problems with the existing sound, but the amplifier was causing the shelf it was sitting on to sag a bit. I wanted something lighter, so I made my mind up to build a 6-channel class D amplifier to replace the 8-channel class A/B. I decided to use pre-built class D modules rather than build something from scratch because I never had a talent for trouble-shooting switching power supplies, and class D circuits seemed to me to be similar.

As much as I would have liked to use Purifi or Hypex products, the price was simply too high, so I started looking at the next tier down in OEM products. I had seen more than a few posts on the forums discouraging using IcePower amplifiers, but the prices are more in line with my budget. I saw Amir’s review of the 125ASX2 on ASR and decided to look closer at the IcePower modules. I also had been interested in the CDA modules from ClassD Audio powered by an Antek power supply. There was very little technical data on the CDA modules, so I decided not to consider them and spent a few days poring over the IcePower datasheets and put together this chart.

Based on total price and the THD values specified in the manufactures datasheets I picked the IceMatch products versus the ASX2 line. In addition to the manufactured modules I need to design a few PCB's to support them and I also added a Raspberry Pi 3B+ to orchestrate a cleaned power on sequence and to run some PWM controlled fans and to monitor some temperature probes. It took me about 5 months of research, design and build the amplifier and I'm content with the finished product. Here is a link to my website with a detailing my build.

https://bellarossafabrica.net/6-channel-amplifier

Here is a Sansui QRX-8001 power transformer for sale.

$45

SOLD For Sale lot of eight vintage 6SN7 tubes, all tested and are good. The star of this lot is a pair of Silvertone tubes that test as new and all within 2% of each other on mutual conductance. The rest are various brands all testing very good. Shipping within the US shouldn't be more than ten dollars.

I have an aversion to open magnetic loops so prefer to avoid air-cored inductors if at all possible. Yes I know they're the most linear but they're also susceptible to noise pick-up and given the choice of lowest noise or lowest distortion, I'll go for the former. I hear from one or two sources that Barkhausen noise is a thing in ferrites but so far I haven't noticed it myself.

I did a brief search and also asked Perplexity AI about manufacturers which are using gapped ferrite-core XO inductors. It only mentioned Bose (but didn't mention 'gapped') and conflated iron-cored and ferrite-cored inductors so didn't bring any clarity. I searched images and saw none of closed-circuit ferrite-cored crossover inductors. However for low values in power supply applications, such inductors are now very much a thing. Here's an example : https://standexelectronics.com/products/pq32-series-planar-inductors/. This example is using flat wire, I'll be sticking with normal round wire for now.

How to design and implement closed-circuit ferrite cored XO inductors in practice ? I'll take an example - replacing the 1.2mH bass/mid series inductor in my Paiyon speakers. I don't have a pic of the original - I dismantled it years ago in a bid to upgrade it and substituted a Sendust toroidal for it. (At that time I hadn't realized that such a substitution wasn't too bright as Sendust has a 'progressive soft saturation' characteristic which makes its inductance vary with bias. Meaning that the LPF cutoff frequency varies with signal strength). Anyway, here is a slightly more complex XO from the same manufacturer as a guide :



The bass/mid series inductor was (I think) similar to these 'bar' shaped inductors which are laminated iron-cored. Its kinda fortunate that the value 1.2mH is printed on the silkscreen of the PCB. As a first pass I selected a PQ core that I had to hand, PQ2020.

The first thing to note is - when you buy PQ cores (try here : https://vi.aliexpress.com/item/1005003707051594.html) they aren't gapped. Gapping is absolutely essential for a couple of reasons - firstly to get a close tolerance inductance value and second to get a useful current handling capability before saturation. Ungapped cores are only really useful for making transformers, not precise valued inductors. Seeing as ferrite is a tricky material to grind down I have gone the route of creating a gap using a few layers of yellow transformer (mylar) tape around the core outer legs to space the two halves apart slightly. My trusty micrometer tells me that one thickness of this tape is about 0.055mm. But how to determine how big a gap to make? This is where we need a modicum of math....

Here's a snippet from a table in FerroxCube's catalog, for PQ2020 cores :



Of note from comparison of 3C81 with 3C90 materials is the core material's characteristic permeability doesn't matter that much, what determines the AL number (and hence, inductance) is the gap length. A bigger gap gives a lower AL value. We use AL to calculate the inductance - multiply it by the number of turns squared to get the inductance value. The bigger the gap, the higher the saturation current but along with a bigger gap you'll also need more turns of wire to achieve your target inductance. So there's a trade - if you have a target DCR for your L that'll determine the gap size you need. If that doesn't allow enough current then you'll need to step up the core size.

As I initially didn't have a feel for the math I kicked off with as large a gap size I thought I could achieve fairly easily with layers of 55um tape and that looked like 620um to me, giving AL of 160. Seeing as to keep the core halves parallel to one another we need to make a gap in both outer legs, the total gap is actually twice the thickness of all the layers of the trafo tape. By observation, the spacing of the outer legs apart creates a same-sized airgap in the centre leg too. Meaning six layers of tape (which gives 330um) results in a total gap of double that, 660um. I'd expect the AL to be slightly lower than 160 as 660um is a bigger gap than 620um. But in fact it turned out to be surprisingly close - the first two inductors measured 1.21mH and 1.22mH on my LCR meter.

With this gap size, where will saturation occur? Here's the equation to help with that : B = (AL * N * I)/Ae.
Here B is the flux in mT, N is the number of turns, I is the current (Amps) and Ae is the effective cross-section of the core which is gotten from the manufacturer's table, for PQ2020 its 62mm^2

With ferrite the maximum B is around 400-500mT. Rearranging to find I we get B * Ae / (AL * N).

Back to the 1.2mH - to calculate N take SQRT (L/AL) where L needs to be in nH as that's the units of AL. With AL = 160 we get N = 86.6 say 87T. Plugging this back into the I equation (taking Bmax = 400mT) the saturation current is 1.8A which might be a bit limiting in practice. I've decided to let it ride and listen to see if I can hear it saturate - a cracking sound apparently - as I raise the volume.

The first pass PQ2020s are inside the speakers now and I forgot to take pics, but I'll try again another day with larger cores.

Hi ! Found here only old discussion about PCI cards like ESI etc... Interesting to get music from modern PC via i2s without USB Audio, any suggestions ?

I managed to stock up on more of the FETs / boards etc than I actually needed.

I've built and tested a few of the remaining boards. They can be used for 24V or 12V supplies, depending on the rating of the MLCC snubber cap.

Open to reasonable offers, but please bear in mind that these are a right faff to solder

Dan

Hi guys,
I am attempting to convert these Apex models to use IRFP9240/240 for the output. I believe both model uses the same circuit and to my knowledge no one build it yet. I let LTSpice do the calculations, transient response, squarewave test and stability test (Tian method), all passed. The only problem that I am encountering is the dc offset and THD at 20khz. Increasing the front end currents significantly increases THD at 20Khz.
All the mods that I've made so far are based on what I've read in this forum. I will appreciate any pointers and solutions on how to fix problems in the present circuit. I have attached the sim files for anyone to check. I am a total noob when it comes to CFA, the reason that I ve been doing this modification is because I only have the IRFP devices.

Thank you!

Albert

Hello all, I've recently had my interest piqued by DIY audio, in particular open baffle speakers, primarily due to the fact that I chanced upon the Clayton Shaw Caladan design. I've been reading the thread on this in here and I'm keen to 'get my hands dirty'! While I love a project (it stops me from crayoning on the walls like a kid with too much sugar intake) I have no prior experience of DIY audio, so I'm keen to absorb everyone's knowledge as far as my puny brain will allow! See you on the Caladan thread!

One used TKD 2P65CS 40-step attenuator for sale.

20k ohm, stereo version. Non-magnetic construction.

Asking $300 + shipping

The problem is I have tpa3116d2 2.1 xhm139 . It is giving low output on subwoofer it is lower than its. Satelite and I give it 21v 5a . So how can fix it.please help.

Thank you

I have decided to publish full measurements of those good performing coaxial drivers. Coaxial drivers is quite a buzzword nowadays, we all know that the concept generally is very good and has benefits, though real life coaxes suffer from a lot of issues, measured performance is far from ideal. and prices are quite high.
I created 2way loudspeakers from both, and 3way from 5" coax + 6" Sica woofer. Based on listening impressions, feedback from hifi friends, and measurements, those drivers are ones of better coaxes available on the market, and Sica did the engineering right. Both sound very good and make good two way loudspeakers and definitely make good midrange-tweeter for 3ways.
Sica 6.5H 1.5CP
Sica 5.5H 1.5CP

Measurements were done in small enclosures with R28 front baffle edges, mic distance 1m for FR and 30cm for distortion, gating 10ms, SPL calibrated, measurement voltage 2.82V, microphone Earthworks M30.

5" coax assessment:

• 3kHz dip in tweeter response is trouble and not nice to look at. It makes crossover design quite challenging. Off axis responses are consistent so the issue is correctable with active crossovers.
• distortion performance is good for basic drivers and does not suggest any big issues
• tweeter top end response is not perfect, though is much better then what we usually see from other coaxes
• we had side by side comparison with KEF LS50, LS50 measurements showed elevated 3-kHz area if I recall well. Sica sounded better in all aspects.

6" coax assessment:

• 3kHz dip again. Off axis responses are consistent so the issue is correctable with active crossovers.
• distortion performance is good for basic drivers and does not suggest any big issues
• tweeter top end response is not perfect, though is much better then what we usually see from other coaxes
• I attached also Vituix 6pack for completed 2way passive loudspeaker, this version sounds very good, has reasonable low end extension and overall listening impression and feedback was there was something really right and good in the sound
• small wrinkle at 800Hz is front port interference

Both are visually very nice drivers, though some details are not perfect, for example consistency of the glue ring and surround centering.
I am also glad they use paper cones with some kind of coating, which means less severe breakups and generally better sound then alu cones (I am not a fan of KEF sound at all, though I admit Meta versions might be step in the right direction to better sound)

Crossover design for both was not easy due to 3kHz tweeter response dips. Standard two way 6" + WG is much easier. Acoustic LR4 at 2000-2500Hz is mandatory due to a) tweeter: rising distortion <2kHz, b) better directivity match, c) uneven response of midwoofer >2.5kHz.

I have lived with those 3 loudpeakers/projects for ~2years and have a lot of experience and comparison to standard 2ways and 3ways. They sound very good and for the price there is very little to complaint about. But ClassIllu 2way (Scan Speak 18W/8545K00 + 6600) beats it in every aspect. It is not fair comparison, ClassIllu drivers cost is much higher, though it tells me that coax is not the only feature that makes a good sound or would be the only prerequisite for the good sound.

Looking to buy any rotary Yamaha amp, I desperately want one whether it's a 50 up to 200. I'll pay most any price that's reasonable, the 2 thousand dollar RA-50 on eBay is FAR out of my budget and unrealistic for that lineup.

I'm attempting to repair an integrated tube amplifier for a friend. I believe it's a Vincent TAC with EL34 tubes. The fault is a dead channel which might have been caused by a bad tube. I've replaced a couple of burnt out resistors, and the dead channel is now alive but badly distorted. I compared resistances in the output transformers and one of them is unfortunately damaged.

My question is: Is it advisable to replace both output transformers even though only one is damaged? I imagine it might be difficult to find a new transfomer with exactly the same specs as the old ones.

Hi there!

My name is Jonas and I am from the Netherlands, 38 yo and working as a mechanical engineer.

Few years ago I got interested in building an amplifier after my dad built a tube amp kit from ELV. I bought an easy to build SymAsym kit and recently finished it. Most work went into sourcing parts and building the chassis. Soldering on the other hand was a 1 day job 🙂

Nice to be around other amp/music enthusiasts!

Jonas

As my title says, I am extremely interested in rotary speakers and amplifiers. I have a strong desire to build one myself, I'd love to build a Leslie or Yamaha style rotary setup for my home. I'm pretty new to guitar, but my love for electronics and all different types of music has me wanting to build myself a dream of a setup and learn to play using that.

Hi all,

I became a Hifi enthusiast during my teens in the 90s, and around the year 2000 on the german "High End" fair I was lastingly impressed by some very nice small speakers, the System Audio SA2K:


Soon afterwards a similar kit from german Scan Speak distributor AOS was published in Hobby Hifi Magazine, the initial version of their Studio 12:


Xover was just a coil for the woofer, and for the tweeter a cap and a resistor in series, with additional RCL in parallel for impedance linearization at the resonance.

I just finished my civilian service and was paid some mandatory "bonus", which I wanted to invest in my first self build speakers, and I decided that the base of the speakers should be a pair of that sinfully expensive Scan Speak-Revelator 5" woofers relatively fresh to the market. As the budget was not allowing to also buy the 9800 tweeters, I decided to take some also new released Vifa XT300 ring radiators which were a good bit cheaper and showed very nice measurements in the magazines.

Lowpass for the woofer and cabinet tuning was taken over from the published AOS Studio 12 xover, the tweeter network was adjusted by using Hobby HiFi measurements of both the Studio 12 speaker and the Vifa and some calculations, and the verification of the result was done with a 5 € Panasonic mic capsule plus HobbyBox measurement software demo version. Still today I think the adjustment was plausible and the result pretty good.

In my romanticized memory at least, they were the coolest speakers I've ever built. I remember well that soon after I had finished them, some colleagues from my apprenticeship visited me and the evening ended sitting in my room in complete darkness, drinking beer and listening pretty loud to everyones music for hours. The guys had nothing to with hifi before, but everyone was absolutely impressed and flashed. At least two of them bought new stereos after that experience as I remember.

The only points of criticism I noticed over time were the tweeter, which sounded a bit lame on the upper end - but never annoying, and well integrated with the woofer. And the sticky coating of the woofers collected a lot of dust...

At some point few years later, I got tired of the very rough build - untreated chipboard, crossovers loose on the floor next to it, a gray plasic tube filled with bird sand as a stand (the sand kept trickling out) and got myself a new system with Canton Ergo something floorstanding speakers and sold the drivers.

Visually it was much better, but the sound was clearly some steps backwards and dissapointing.

Now, about 23 years and more than that number of speaker builds later, I want them back. They were absolutely lovely.

The easiest exercise would be to take just similar drivers and rebuild them. To overcome the mentioned drawbacks, just changing the woofer to one without coating (15W/4531G00):


And to overcome the bit lame highs, changing the tweeter from ring radiator to dome type with wider dispersion >10kHz (D2604/833000):


After having carried this thought for some time, I decided that would be too easy and boring as a development task. So I want to extend the concept to a 3-way floorstanding speaker, LR2 acoustical slopes, stepped baffle for tweeter sound origin / phase aligment. Challenge is to achieve good on-axis and power response with as little crossover parts as possible.

The midrange I want to use is fixed, Scan Speak Revelator 15M/8631G00.
According to initial simulations with the traced manufacturer measurements in Vituixcad, driver response and baffle diffraction in eclosures with 22-25cm width will complement each other very well:






Still not decided if I should take 1x 8" or 2x 6" as woofers:






Also still thinking about the tweeter, favourite is still Scan Speak D2604/833000 as mentioned before, but other tasty canidates are also on the table, in particular

the new D3004/602200:


the classic D2905/970000 as used in the SA2K:


the D2608/913000, liked and recommended by many:


Any thought, experiences, recommendations to a nice tweeter with matching sound signature?

Woofer section is the hardest choice. I like the visual appearance of the solution with 2x 6" more, but initial simulations with common canidates, e.g. SB17NRX2C35 show low impedance and too high sensitivity when 8 Ohm types wired in parallel, and too low sensitivity with 4 Ohm types in series.

Any recommendations/ideas for the woofer section from you? I'm a bit lost in analysis paralysis and would be happy for some feedback and discussion especially to that question! Thanks! 🙂

Best regards
Peter

Hi,

Trying to get info about the Tony Gee Mezzo Calpamos design. Did you have a chance to listen to it?

Thanks,

Marijan

Anyone got a single Phase, ideally UK outlet, Variac for sale (or loan close to Oxford?).

Thanks!

Hello, i just had a problem with a TPA3116 amplifier that worked fine for 2.5 years... Then, few days ago, it failed in a weird way:

The bluetooth chip in that board blew to smithereens for no apparent reason. I was not using it though, i bypassed it because it was garbage. The external (much much better) bluetooth module is intact. But the TPA3116 is NOT intact...
There is no output. No output at all. The chip is in SHUTDOWN mode, and i cant wake it up and make it work like before. The only way is to pull the SHUTDOWN pin high with a resistor to VCC. But it is sketchy to do and that resistor would block the heatsink over the Tpa3116.

Can someone help me figuring out what actually happened? The fried Bluetooth chip was on its own, i dont even know how it managed to damage the TPA3116...

The mute pin is LOW, so the outputs should be enabled... But the FAULTZ pin is LOW, which means it is in FAULT mode. But by doing that trick with the resistor, the FAULT mode goes away and the outputs are enabled. Disconnecting that resistor puts everything in FAULT mode again.

Before, it worked fine... Is the chip partially damaged? Maybe if i replace it the problem goes away?

Hello everyone. I’m replacing the selenium rectifiers in my old Mac MR67 and there’s some debate about how to do this. Amongst all the posts and threads I’ve read, a number of people have said the Schottkey sic diodes are the way to go, but they are in the minority; nevertheless, I chose a pair and in doing so, I went by spec, choosing the one with near highest performance. What I didn’t realize was that the heat sink is tied to the cathode and if it touches anything will result in an immediate short. There are sic diodes with isolated bodies, but not the pair I purchased. How good or bad of an idea is it to cover them in heat shrink as a way of insulating/isolating them?

Please let me know and thanks,

John

I have a pair of 3-way (decent quality) speakers that have been stored for several months and need some playing time to come on song.
I have a spare amplifier (150W mono-block).
Any drawback to my wiring the speakers in series to the amp and leaving them playing for a weekend out in the workshop ?

A fascinating leap in technology using Femtosecond lasers to "project" an image in midair via plasma.

Imagine the use cases here visually, but maybe even audibly, some day? If you can excite the air like we do now but via lasers that are safe to touch why can't it be modulated and emit sound?

https://spectrum.ieee.org/femtosecond-lasers-create-3d-midair-plasma-displays-you-can-touch

Xtant x604 4 Channel car amplifier for sale
4 x 75 Watts at 4 Ohms
4 x 150 Watts at 2 Ohms
2 x 300 Watts Bridged Mono at 4 Ohms
Front + Rear independent crossovers
Balanced/Floating input--helps eliminate ground loops
Noise Gate
Thermal, overcurrent + low voltage protection
Voltage 11--15 Volts
Frequency Response 20 Hz--20K Hz
Pulse width modulated power supply
Distortion at 4 Ohms <.2%
Fuse included
Stainless steel housing
23 5/8 inches x 10 9/32 x 2 5/32
Have original box, owner's manual + installer's reference manual
Amp approximately 15 years old
Sat unused in original box(installed in 2023, removed in 2024)
Payment Paypal Goods + Services
$550 shipped

As mentioned in my introduction, I am working on finding a short in the captioned DIY amp. I have checked and rechecked wiring, connections and solder joints. I have checked continuity of virtually every wire and every tube socket pin. I have rolled rectifiers and power tubes and preamp too.

I fire it up through a variac plugged into our 120vAC main and then a light bulb current limiter plugged into the variac ....no smoke, no odor of burnt anything, no arcing in the dark. The thing starts life as it should and about 30 seconds after power on, the current limiter goes full on bright, so I shut it down and keep looking.

I know that my variac and current limiter are functioning as I tested a good amp on it. Like I said above, I have tested all resistors and caps for values within tolerance, no broken wires no bad solder joints...I'm at a loss! Oh, I even checked the resistance on both sides of both transformers before installation and after.

What am I missing?

Schematic attached.

Hello, Gang. I hope the New Year is finding you all well. I'm going further down the audio rabbit hole for sure. I had a few tube amps fall in my lap and it's re ignited my curiosity for valves. I picked up Jolida JD 302B and received, on loan, a Dynakit ST-35 and a Macintosh MC240. They are all in various conditions. I'm here to learn more about mods and the intricacies of the designs. I'm looking forward to the collective wisdom of the group. Thank you! Here is a pic of the 302b. Evidently this one has been worked on. I'm hoping that someone can tell me why they did what they did.

I pulled out my 199C from stoarge after 20 years (pretty much new condition). Battery was bust, put in new OEM battery.

Scope powers up and all menus selections work. But no signal detected from scope or meter inputs.

Any ideas on where to go? I did spend a bunch of time on the internet with no luck.

Regards, Vinay

I just got my new DATS V3, installed the program, and hooked up the device. It is properly detected in Control Panel/Sound, but the DATS program starts then immediately closes.

No other audio programs are running, and I've tried all compatibility modes. Here's the system:

Window 10 Home
Version 21HZ
EX Build 19044.2006
Features Experience Pack 120.2212.4180.0

Any ideas, or will this just not work in Win 10?

So far I have repaired and restored several Revox B750 integrated amplifiers and I have always noticed a presence of a background noise. A typical transistor rustle which goes up and down with volume control and changes flavour with tone controls. I believe that the cause lies in extensive use of older transistors, particularly in preamp sections, such as:
BC107
BC140
BC160
BC177
BC179
BC190
BC266
In addition, I believe part of the noise comes from obsolete voltage regulators: 78/79GU1 and 78/79M20.
As I do not have an in-depth knowledge of particular types of transistors, I would like to know if some or all of the listed transistors are known as noisy and would replacing them with more modern equivalents reduce the background rustle. What is your opinion on such "updating" of the amplifier and could you suggest replacement types for these transistors? On the other hand, would there be a downside of such replacements?
Thank you in advance for your replies and advice.

SOLD

Miro PCM1704 DAC board for sale.
A pair of PCM1704 J graded chips on the board. These are recycled chips from a reliable seller, removed with proper care. They are not bought from random sellers in Ali or ebay.
Fake chips won't work, don't ask me how I know.

What you need to provide :
1. You will need to give it PSU with rails +/-5V (Analog) and +/-5V (Digital).
2. i2s source (Amanero Combo384 USB-i2s, JLSounds i2soverUSB are some examples) is needed to feed it in order to play music. u.fl connectors have been soldered on the board in case you wish to use u.fl cables for your i2s signals.
3. Chassis, wires, connectors etc

Board fully populated with good quality caps eg. Elna Tonerex, Nichicon KZ, Wima Mkp, Panasonic acrylic caps, Samsung ceramic caps. all the signal resistors are low noise non-magnetic resistors with copper leads, good quality Nextron IC gold plated contacts sockets. The IV resistors are expensive Vishay Angstrom hermetically sealed resistors.
https://www.vishay.com/en/resistors-fixed/hermetically-sealed/

The IV Stage has a pair of AD811 op amp with heatsink mounted. The board has been modified (tracks cut, caps added, ) and decoupling has been done differently from the stock board to allow the AD811 to work properly. Hence this board is optimised for the AD811. To me, this is the best op amp IV stage for the PCM1704. I did not bother to revert to stock design for other op amps after trying this. The AD811 IV designed by Grunf has been discussed here :
Of course the IV will still work with other op amps, but as mentioned the mod is optimised for the AD811. This mod is reversible if you know what you are doing, but I really would not bother.

Payment by PAYPAL FF please.
DAC + shipping registered & tracking = 225 USD or preferably 308 SGD (Singapore dollars)

Hi,
I tried to use a mini digital oscilloscope (Zeeweii DSO3D12) to visualize hum, but it's kinda act weird. Not sure if I hook up correctly.

I've just recently built a tube preamp with recommendation from this thread (https://www.diyaudio.com/community/threads/6j1-china-preamp-thoughts.309876/). It sounds fine but it has some hum, louder on the left channel. I connect probe ground to signal ground and probe to left output. Despite loud hum from the speaker, the scope show no signal. However, if I float the probe ground, it show 50hz signal at few Vpp. Using a DMM, it also show 50Hz.

What should I adjust my setting? Please suggest.
AP

Looking to put together a parallel notch filter for some Peerless 830869 drivers I have, to kill the peak and the associated sub-harmonic distortion.

Is this the right place to start? https://www.diyaudioandvideo.com/Calculator/ParallelNotchFilter/Help/

https://hificompass.com/en/speakers/measurements/peerless/peerless-830869

With f1 ~= 1800 Hz and f2 ~= 2700 Hz, I get values of roughly 66.7 uF, 1.67 mH, and 1.44 ohms. Does that make sense?

This is what i made up in ltspice, it works like crap becuse i probably missed something

Now I'm wondering, due to air dry alkyd varnishes like Elantas Elmotherm 009-0008 getting more and more expensive, are they somehow superior to regular alkyd boat varnishes you'd find at regular paint shops? And to what extent? Drying time? Anti-corona additives? Could regular alkyd varnishes contain offensive to the transformer chemicals?

I wanted to build the Kondo M7 all tube pre-amp, but discovered that the company founded by Kondo has taken the design a little further and my project will now take advantage of this to see what’s changed, what hasn’t changed and deliver the ultimate M7 for my system. The latest products being sold by Kondo Japan are very expensive so DIY is particularly attractive.

Although mine is a mono system what comes out of this still applies to the stereo version. I’m going to build from scratch, no ready made kits or pcb’s for which other threads exist to help those interested in that approach.

I hope this thread will be of interest, it’s going to look a bit like a diary of my build as it goes along. I really want it finished over the coming weeks.

Contents (by Post #):
25, 38 & 41 - main H.T. Power supply, schematic shaping up on #46
30 - adding a heater winding to an off-the-shelf power transformer
54 & 61 - shunt regulated heater supply
77 - H.T. power supply board build
88 - fixed -20dB attenuator design
90 - Line amp schematic
97 - Phono amp schematic
106 - Line amp square wave test results
111 - Line amp frequency response test results
112 - RIAA curve compliance test results
35 & 115 - RIAA design analysis, ‘correcting‘ the OEM design
118 - the finished unit

Dea DYIaudio community
I’m Marco, another fellow from Italy

My father passed me a strong passion for good old hi-fi tech and music on vinyls 🙂
I had the chance now to upgrade a bit my audio system and need some how to make it sound at best

Thanks in advance

I've got a CS-800X that's used for a "stereo" in a shop for many years. Doesn't see a lot of high output use, just running ambient music. Yesterday it started buzzing loudly so it was switched off. I turned it in today to debug and it initially buzzed loudly alternating left and right channels so I turned it back off. When I powered it back up again now it's just flickering green on the power light, again alternating between channels. The relays are clicking intermittently. DDT lights are off, speakers are fine (running on another amp now), fuses are fine and have never been replaced (by us), no other indication of issues.

I took the lid off and immediately noticed R103 on the power board (20W 400ohm) is coooookkkked, it's heated the adjacent areas around the board but looking at the schematic it looks like it's related to the fan but not much else?

~75V on both capacitors

Going to start towards verifying +26V and +/-15V output. Any other suggestions on where to start/what to suspect? Seems like it should be on the power board given that it's effecting both channels but that could turn out to be a bad assumption 🙂

Perry Marshall's Live Edge Dipoles inspired me to study them with the aim of developing my own variation on the theme. To do so, I had to develop Vituix models for the dipoles and for the Uframe, which I'd like to share. Perhaps someone can compare model predictions against their speakers.
Dipole modeling in Vituix is well known but running the model made clear that with dipole coax drivers, the coax mid woofer cone was being used over a much wider range than done in multi-way open baffle speakers and that there were consequences to that.
A U-frame model starts the same as a dipole model. Per Linkwitz, the acoustic impedance mismatch at the back of the U-frame attenuates the rear wave. Per Krekovsky, the U-frame's 1/4 wave resonance needs to be tamed which makes the Uframe response cardioid like in the low end.

I will do separate posts for each of my models

Hello friends. Im glad to join you here.
Love to bild speakers and amps. That is my favourite hobby for many years.

This totally reminds me of walking into a class for the first time and the teacher has you stand up and say something about yourself, which then leads me to the movie Stripes….. I can’t remember the guys name that “I like fast cars and fast women”.
I have no idea what to put here, I’m only posting here because I have to to post elsewhere on this site.

Disclaim: DIY at your own risk. No responsibility will be taken if precious amplifiers/speakers are blown.

Introduction
More and more SMPS are used in audio amplifiers. Meanwell desk SMPS for the newest V-FET amplifier is used. The feedback to use SMPS in the amp from all lucky winners is generally positive.

SMPS
Phoenix Contact Quint-PS/1AC/24DC/5 is selected for the test because of seeing and using them a lot. Its output voltage is 18-29.5VDC adjustable, very handy for future testing and different amps. The output current is 5A, but it has a boost mode, which allows 7.5A at 24VDC if the ambient temperature is not over 40°C. The residual noise is 40mV P-P, which is very low. They can work in parallel to increase the current or series to double the voltage. It is very well built, metal case, 105°C Rubycon and Nichicon capacitors. And all other components look very solid.

The most important feature is the build in protection function. They have built-in protections.

Capacitance Load Test

“True audiophile nervosa” cannot tolerate the oblivion of their best sounding, huge, beautiful capacitors from their beloved amplifier power supply. Some capacitors are be added in.
In the spec, the SMPS used does not list a max direct load capacitance load. But other similar SMPS can have 3000uF-8000uF direct capacitance load. Started from 1000uF and ended with a 10000uF capacitor, the SMPS can start. But one of the PS started oscillation on pure capacitor load. A 4.7K resistor is added and give the PS some small current load to solve the problem.

Does anyone know the parts number for a replacement woofer for the Tannoy D700? A friend has a pair with a missing woofer - I assume it got sent for re-coning at some point and never came back...... I could take the remaining one out and measure to see if I could find an alternative pair, but it's definitely option two. Any info - or replacement suggestions - would be most welcome.

Be keen to get them working again - a quick internet scroll seems to rate them very well.

I don't know what to do.
The amp only turns on after a few tries after being pluged in, but once it turns on it will work fine and then i can turn it off and on and it will work as intended untill i unplug it for a random amount of time, and then it goes back to not turning on.
If i remove the cover to try to find the problem, the amp turns on no problem even if left overnight, so the problem goes away
Any ideas on what could be wrong?
Attached is the power supply section of the amp

If i understand the circuit correctly
the switch turns on mains via a inducter to the main rectifier and capacitors via two inrush limiting resistors. Before the rectifier power is bypassed to transformer T101 that feeds a 7815 voltage stabilizer that powers a IR2153 half bridge driver that drives T104 so that it will provide all voltages needed by the amp and turn on the power relay to bypass the two inrush protection resistors.

I have used Alpha pots (made in Taiwan) in the past. I ordered a batch of pots for a project and have found that although they still have a nice smooth operation, their resistance tolerances leave a lot to be desired. In dual pots, the sections may or may not match. A 500K dual pot may be 500K in one section and 450K in the other. In a volume control, at lower volume levels, this causes the channel balance to shift. To get a pot with both sections the same resistance, you have to order a bunch and weed out the bad ones. The audio taper pots all seem to not really be an audio taper. They are more like linear until near the end of rotation, then suddenly the resistance changes. Mechanically they are nice pots, electronically not so much. Any suggestions for more accurate pots?

Poor Man’s Planets

Some time ago, in a grey November day I decided to do something about the sound of music in our bedroom. We used a Bluetooth speaker located in the top shelf of our bedroom commode/sideboard, which was neat but no real stereo.

Since I’m a bit of an audiophile naturally I would prefer a (cheaper) alternative to Duevel’s Planets, which are superb sounding omnis with a decent amp, but meanwhile around 1k €/$ a pair and quite large for such a small room - hence the name for the project.

Disclaimer: For me the greatest motivation to build something, whether it is artwork, music, software, home improvement, bikes or this speakers is to create and get something new, which wasn't there before and cannot be acquired otherwise – the days I was poor in any meaning are long gone.

Searching the internet and some retailers I found out about a building kit for classic omnis – as satellites with optional sub woover which would be a basis for some modifications but still 600 to 700 a pair – with unknown sound quality, and no builder or user feedback available … the idea was to use the shelf board as kind of box volume / semi open back solution for the “satellites”…

During searching for wood materials to make the base board from, the Focal Performance Expert Flax PC165F dual speakers came along since I was searching parallel for posibillities to simplify the design, and they are two way speakers and have a near perfect wood-color fabric membrane, and so the idea of simpler “Planets” with only one diffusor/reflector was born.

As they arrived I got my first headwash during this project: “No, you will not build such ugly color-mismatching wood extensions to the shelfboard!” and… much more later “Perhaps in white*, and I don’t want to see any black from the bed!” harsh conditions – I was speechless for some time – because I introduced the project some time ago – and it was wood the whole time.
*which is the second base color of the sideboard

So… time to redesign the materials and composition, from a straight plywood multiplex composition to a plywood – white plastics composition with white ironed edge-Tape around.

I changed the planet holder bows to chromed copper pipe, and bought white Christmas balls in 10cm diameter and a collection of 2 to 3cm diameter ones because it wasn’t possible to figure out the size of the sockets without buying and dismounting them.

And the main board to precoated white shelf boards from the hardware store.

After Christmas (I ordered my own present – a 200W Douk Audio ST-01 PRO Mini HiFi-tube amp)



…all materials had arrived I started to build.

As built plan (after) first build:



In a first step we cut the 125mm Sewage elbows parallel to the shelfboard in my father’s workshop.



I had to remove the inner section later.



I made several cut outs from the plywood until it fits.



Two layers of plywood were glued together/laminated and screwed+glued to the parallel boards, which have been screwed to the sewage-elbows before,





and the upper bows filled with brick-layered cut wood strips – I was not able to saw out the exact needed shape with the electric jigsaw, and was not enthusiastic enough to do so with the manual saw.


I had changed the width of the horizontal ear boards because the planned width seemed too narrow during building. In the effect I had some trouble with cutting and glueing the plastic board because I had to mirror one side to minimize waste and gaining enough area.






Turns out copper plumbing-Ts are eighter too large or too small, such I ended with screwing a short section/ring of 30mm plastic pipe to a wooden peg which perfectly fits in the chromed copper pipe bow. In the larger glass balls I put a wooden strip with a hollow nut in the middle, and in the smaller glass balls I glued a fitting mechanical bolt/screw and screwed it through the plastics ring together.



First test of the setup was sobering, I was disappointed, the sound was telephonic with a lot of resonances and nearly no bass. I had to ad to add additional wood bars behind, and wood strips to the front board to eliminate resonance of the boards and sound damping layering in the pipe-elbow ends, the elbow itself and a squared absorber foam block in elongation to the front board



– And to finally get some bass I added a passive bass reflection absorber box in the middle of the shelf.



And I added another wood block as support beam for a furniture foot used as a clamp to press the upper side of the speakers’ boards against the top board of the side board.

Now I was satisfied with the sound for some time – real good jazz speakers for soft to medium volume, with very precise stereo position and depth… And with some SciFi finish…



In May or June I built additional front boards from new 60cm long shelfboards (and remainders from the building process as support in the back) to increase the volume of the boxes mainly for bass…

It got more bass, but lowered brilliance and a second “headwash”, she didn’t want to see the new fronts again – too large!

So I only tested them from time to time but was never satisfied myself…

Some weeks ago I had another “sting” and sat down to redesign the speakers in terms of used volume and resonance prevention – I ended up with larger, slightly downward pointing front board - preventing steady front to back and “circular” reflections. Second topic was a slightly backward aimed /”opening” back board to prevent in phase front to back reflections – but both would require a real wood workshop for milling straight flush egdes – better tools and a complete disassembly and nearly total rebuild of the speakers… both a bit out of reach…



But since I got the “sting” I decided to do it half way! I used the electric saw to remove half of the back boards and the wood strips to the front. Then I added the 60cm front board which I cleaned from the supports and did it in a slide angle as planned and shifted so only 12cm longer, as long as the added absorber foam block before, connected / supported with wood glue, wood strips and 6 wood screws. Layered with flooring fabric at the ends – the absorber turned 120 degrees inwards. So there is a nice slight bass reflex horn like design (including the passive box) now.



The appearance changed a bit from technical (visual pipe elbows) to clean Bauhaus style.





The sound is brilliant, precise stereo position (i.e. Yosi Horikawa – Bubbles), room filling – great depth esp. in ambient (like) productions (i.e. Pink Floyd – nearly any Intro, esp. High Hopes [from the division bell], Hattler – Sand am Meer [from Warhol Holidays]; Carbon Based Lifeforms – M [from Interloper], Massive Attack – anything from Mezzanine, Dan Gibsons Solitudes – Rocky Mountains Suite), decent bass – I am very happy and satisfied …

…awaiting the final “headwash” when she notices the larger front boards, if, ever…

probability sinks, weeks in the aftermath … 😉

in the moment i'm writing this i'm lounging on the bed, listening to Moby and Two Lanes and simply enjoying the great sound...

Hello, I have spent part of this summer to try to build a nice two way speaker. I have used VituixCAD2 to help with the layout of crossover. The speaker elements are Scanspeak D2010, 851300 Tweeter (oldish but not used) and Monacor SPH-165KEP. Unfortunately there is no measurefiles from ScanSpeak or Monacor, so I have used Vituix to plot. It seems to work. I posted one time earlier here at diyAudio as introduction and was recomended this forum/thread. On recommendation from @knotscott I tried to make a RC zobel to improve impedance. Crossover at 4000hz is my goal and also what ScanSpeak tells. If I raise resistans on Monacor everything falls apart in some way, but impedance can be set to 6-8 ohms. Any suggestion is welcome.

Hey guys.

I have the chassis of an old Alesis poweramp, which I would like to turn into a relatively low power (20-40 watts I guess) stereo speaker amp for my living room TV.

I'd like to use the chassis as-is, and each channel has space for 7 transistors on its heat-sink. Is there any class AB design that you guys could recommend? I'm willing to design my own boards if needed, no need for a complete DIY kit.

Thanks 🙂

It´s 135 mm
Mark´t 8-9 ohm at the backside, but no modelnumber.

Regards John

A couple years back I went from a pair of passive dayton based bookshelves to a fully active system based on the daton PCX-12 coaxial. Details can be seen here: https://www.diyaudio.com/community/...s-the-box-less-important.392703/#post-7222109

These were a real learning experience from being my first go at active XO's, measurement, and PA gear. From the active XO side of things, I'm not looking back. The results that I have achieved (after investing the time) have exceed expectations that i dont think my patience could match rolling components in a passive xo.

Being PA coaxials with a small wave guide, the speakers have a very very narrow sweet spot for a residential sized room. I thought about experimenting with different waveguides but dont think I could sufficiently close the gap. One thing these do deliver though, is the party, and this was a design target for these. The super small sweet spot is 90% of my motivation to build a new set of speakers but solving this has many avenues that I could take. Some of my ideas are below, id be interested in hearing others suggestions.

1. Re-use the drivers but put the CD in a proper horn. Bonus, it only costs mdf and time. But again, the directivity may leave me lacking.
2. Go back to a traditional dome tweeter and build a set of 8" MTM's. This will help my LF xover to the sub and hopfully give me more even bass in the room/floor.
3. Make a 3-way 6.5" MTM with a 10 or 12" sub in each and leave the low lows to the UM-18.
4. .....Something else that wont break the bank

FS Four vintage US made Tung-Sol 12AX7 tubes. Tested and strong on TV-7D/U tester at 40-42 where 32 is passing. Price is $49 plus shipping within the US. Payment by check or MO, no Payal or other online payments so please don't ask.

Hi Folks,

here is an embarrassingly simple-sounding question: can I connect two power outputs of a 9V power supply to get enough current for a more power-hungry digital pedal?

I am considering getting a pedal board with an integrated power supply, probably this one: https://www.amazon.com/dp/B0CT34HZRG

The problem is that these board's power supply come with a bunch of 200mA outputs, and I need 300mA for my main pedal - Flamma FS06 amp modeler. So I was thinking of getting a splitter cable like this one (https://www.amazon.com/Mozeat-Lens-Splitter-Electric-Adapter/dp/B0CZ8JNS12) and just use two 200mA sockets for the Flamma.

Is there any reason it won't work? Thanks!

Hello,
How much does a preamplifier impact sound quality? Should the electret capsule primarily determine the sound quality? I’m considering purchasing the AD620BRZ, INA849DGKT, AD797ANZ, and MUSES03 for testing, but I’m unsure if they will work well together. I’m working on building a microphone for musical instruments and would appreciate any insights.

Thanks!

Hello,

I have built a subwoofer box for the budget subwoofer "GRS 15PF-8" and it didn't turn out the way i wanted/expected it to, let me explain. I have installed winisd to do some calculations on what box/port size ect. I have watched some tutorials from "Diy Audio Guy" on what parameters I should look at and what they should be. And I came to the conclusion that a box of 50x50x50 cm =125L or a little over 4 cuft minus the subwoofer air replacement is about 4 cuft and a port of 4x50 cm of 50 cm long gets the tuning frequency's matched up pretty well. This configuration gives a Transfer function magnitude graph that looks like this
with almost an 16 db gain at 29 hertz. Now here's the problem: I built this subwoofer box and it does not sound like this AT ALL!! It more sounds/feels like the 16 db gain is at 60 hertz instead of 29 hertz. I have taken it outside to ensure it is not something with my room and it shows the same results outside. I don't know what i did wrong here and i would really appreciate any answers to what it possibly could be.

Nanno Haasjes

ps. the amplifier i'm using is the skytek spl 500 (a little overpowering it i know)

Ha! (mods don't lounge this yet)

After dozens of diy experiments under a wide range of (domestic) conditions and speaker/listener placements (including height), I'm reasonably convinced by the empirical evidence and common-sense inference to state a theory of soundstage imaging depth. Bits had been posted over time to the Full Range Photo Gallery and various threads such as on-going "ragged coaxials".

Metaphysics or psycho-acoustics -- a progression?

Claim 1: It is the monophonic recording-through-to-playback-chain that is responsible for enabling soundstage depth perception; the stereophonic L/R is responsible for enabling horizontal directional perception.

Claim 2: A necessary and sufficient condition for a monophonic audio chain to enable the perception of soundstage depth that projected well beyond the speaker, is close time- and phase-alignment (coherence), including very-high-frequency components of the sound.

I call this effect "audio-lensing" and experienced it quite dramatically, replaying phone-recordings of my coherent near-field 15in/ceramic-tweeter "reflector-coaxial" (playing virtuosic violin music). Aiming the phone-top-end (Vivo iqoo Z7 with stereo speakers at the ends) in various directions and at various distance-combinations from self, and room boundary 1-7 meters away, the sound source was heard to project/float mid-air far from the phone and near or just-past the wall in the pointed direction. In one extreme case the sound "played" from second-floor balcony at ~7.5m. The phenomenon as observed was analogous to "lensing" in that the distances from the phone to me and to the perceived source were in reciprocal relationship; source was farther away if phone was closer to me (and the reverse). Again, this was a stereo-phone playback with one end-speaker pointed away, of recordings of a monophonic coherent near-field 15"/ceramic-tweeter 2-way. This phenomenon was not observed replaying other people's sound-clips but I did not have time to test very many.

I will be adding experimental observations I've had, and inferences to back up this theory. And audio-clips if possible. I'd appreciate members sharing their experience and insight.

https://www.diyaudio.com/community/...ials-with-ragged-response.408887/post-7783316

Pico's Dumb (ie Pico is Dumb) Biasing Trick for F6 and other Amps

As you may or may not appreciate many devices have a positive, negative, or virtually zero temperature coefficient.
Most mosfets have a positive temperature coefficient, ie as they heat up they draw more current when biased with a constant voltage source applied to the gate of the mosfet (provided the bloody voltage is adequate to turn it on).

To reduce the effect of this increasing current draw as the device gets hotter we can do a few things.

1) Reduce Delta T of the devices, eg larger heatsinks, better thermal pads ie improving Case to Heatsink performance, etc

2) Using source degeneration which acts as a form of negative feedback, ie as the device attempts to draw more current, an increasing voltage drop occurs across the source resistor which effectively reduces Vgs which then stops or reduces the amount of thermal current drift.

3) Using NTC thermistors in the bias circuitry, which effectively reduces the Voltage at the gate as the thermistors heat up, eg as seen in F5, and elsewhere. I used a similar method to this, in F4 beast builders ie building push-pull amps (mostly with hockey pucks) with zero degeneration.

4) Active bias control circuitry, optocouplers, hall sensors, discrete designs.

You can obviously also combine some or even all of these methods, to get the result you need.
There are probably quite a few more techniques than this, but I am telling the story and I don't want it to be batshit boring.

Even though I have successfully used method 3, and 4 in the past, I don't like "intelligent solutions", I like dumb simple solutions that don't require maths or too much intelligence.

I have often thought, there has to be a dumber way to do this.

So I am sitting on the toilet (it always happens like this), and I am considering my options with regards to voltage references, TL431, LM329, Zeners, Leds.
I start thinking about Zeners and leds, since they are dumber than the other devices, and remembering that Zeners below 5V have a negative temperature coefficient and zeners above 5V have a positive temperature coefficient, the light bulb turns on "aahhh you bloody dumb bastard" and gave myself an uppercut for not considering this earlier.

Many here have either personally built the F6, or are at least aware that in many cases, the 5.1V zener shown in the original circuit diagram is not quite adequate to produce the required voltage at the gate to bias the F6 to the required value.
Most of us have used 5.6V, 6.2V, 6.8V zeners etc, some have used LM329.

Well, all these devices have a positive temperature coefficient, you could probably say that LM329 is effectively zero but it has a very small positive temp coefficient.

So, what is stopping us from using 2 smaller valued Zeners to achieve the required zener voltage eg 2 x 2.7V zeners, and achieve a slight negative temperature coefficient.
LEDs also have a negative temperature coefficient with regards to Vf, but we will first consider comparing Zener diodes.

Anyway, so I decided to compare the observed measured differences in biasing up a Vishay IRFP150 mosfet (with zero degeneration) using 3 different zener configurations:

1) 2 x 2.7V zeners in series (effectively 5.4V)
2) 5.6V zener
3) 6.2V Zener
4) 3 x Green LED LTL 4231N - tested at a later date

The zener diodes were fed around 5mA in each case (more detailed information below)

A multiturn trimpot was used in each case (just like F6 circuit) to achieve exactly 3.925V at the gate.
I used zero degeneration on the mosfet to better illustrate the effect.

Results
------------------------------------------------------------------------

Case (1) 2 x 2.7V Zener Configuration
Initial Vgs: 3.925 V
Ambient Temperature: 21.8 deg C

Id at turn on: 1.32 A
Id at thermal equilibrium: 1.68 A

Vgs at thermal equilibrium: 3.899 V

Delta Id after thermal equilibrium: 1.68-1.32 = 0.36 A
Delta Vgs due to Zener: 3.899-3.925= -0.026V (negative 26mV)
------------------------------------------------------------------------

Case (2) 5.6V Zener

Initial Vgs: 3.925 V
Ambient Temperature: 21.8 deg C

Id at turn on: 1.32 A
Id at thermal equilibrium: 1.95 A

Vgs at thermal equilibrium: 3.936 V

Delta Id after thermal equilibrium: 1.95-1.32 = 0.63 A
Delta Vgs due to Zener: 3.936-3.925= 0.011 V (positive 11mV)
------------------------------------------------------------------------

Case (3) 6.2V Zener

Initial Vgs: 3.925 V
Ambient Temperature: 21.8 deg C

Id at turn on: 1.32 A
Id at thermal equilibrium: 2.25 A

Vgs at thermal equilibrium: 3.954 V

Delta Id after thermal equilibrium: 2.25-1.32 = 0.93 A
Delta Vgs due to Zener: 3.954-3.925= 0.029 V (positive 29mV)
------------------------------------------------------------------------

Brief Discussion of Results

As predicted during my toilet brainstorming, the 2 x 2.7V zener in series produces an excellent result, with a delta Id between turn on and thermal equilibrium of 0.36 Amps. This was achieved using the negative temperature coefficient of a 2.7V zener to our advantage.

The 5.6V zener is twice as bad, and the 6.2V, almost 3 times as bad as our 2.7V zener setup.

The test was performed on a large heatsink (relative to the heat dissipation of the device) flat on the floor, with excellent ventilation.
If the same test was repeated on a relatively smaller heatsink with regards to dissipation like one you might be using, and performed inside the chassis of an amp, we would expect to see an even greater positive affect with regards to using 2 x 2.7V zeners.

However, if I were to repeat this test exactly as performed above using degenerating resistors the results would be closer together.
This was merely done the way it was to clearly illustrate the effect, and I always try to avoid any kind of degeneration, so this kind of thing is of interest to me.

You could also try 3 x 1.8V Zeners for an ever greater effect.
Or you could use 2 x 3V or whatever you might have. Basically anything below a 4V Zener configured for the voltage you need, is going to have a nice affect.
EDIT: A 3 x LTL 4231N LED combination was also tested and gave favourable results like 2 x 2.7V zeners, however it has better regulation than the Zener combination.

It's up to you if you want to try this out. I am not into preaching, just sharing.



Test Conditions:

Zeners tested:
5.4V (2.7V x 2 in series) BZX55C2V7-TR
5.6V BZX79-B5V6.113
6.2V BZX79-B6V2.113
LED: LTL 4231N

Mosfet:
Vishay IRFP150

Trimpot:
10k 0.5W Bourns 3299Y series

Resistor feeding current to Zener
3.3k CMF55 (zeners biased at approximately 5mA - close enough)

Powersupply Feeding Circuit
Linear regulated lab powersupply set to 23V

Heatsink
MF35-151.5 just laying flat on ground.

Ambient Temperature 21.8 deg C

Biasing Circuit
F6 basic biasing circuit.

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