Hey everyone,

I've been reading some books on designing/building a speaker cabinet. It seems like a fun project over the winter, and I'll have some time.

I do have a question though about speaker enclosures. I look at a speaker, for example the DA175-8 7" aluminum cone woofer. It has parameters of 8 ohms, Qts of 0.58, Vas of 16.3L, Fs of 39Hz. When I use online calculators to determine the optimum enclosure size for sealed vs ported, I get 33.5L for sealed, and 54L for ported (using this calculator - https://www.diyaudioandvideo.com/Calculator/SpeakerBoxEnclosure/)

But when I go to various websites, it lists this:

Optimum Cabinet Size (simulated using something called Bass box 6 pro):
Ported: 1.2ft^3 (33L)
Sealed: 0.46ft^3 (13L)

So what's the deal? Why is there such a huge discrepancy between what's listed on the manufacturing website, and what the online calculators show? When I look for completed builds as well, many of them look pretty small based on these numbers, so I'm a bit confused.

Thanks.

Ok I just got new parts but the orange rubber or silicone I'm not sure exactly what it is but on one of them where the semiconductors had burnt made little hole thru that can I still use it or do I need a new one and if so anyone know where I can buy one

Hi I have a Linn lp12 the motor is probably very old . And in thinking of changing the motor and PSU . Probably a Zeus PSU . Which Linn motor would be best suited to fit

Anyone have a schematic for this amp ?

PC # PC-4347-C

Hi there,
Does anyone have pdf copies of Audio Amateur magazine, year 1986, in pdf format, to share? I'm missing that year from my collection and would like to complete it.
Thanks in advance, Vedran

Hi.
I asked in another thread if such a configuration would be possible and in the meantime -waiting for the discussion to go on- I squeezed my neurons to the utmost and by copyng and pasting the schematics on the data sheet I came to a circuit that very likely will blow and set my house on fire. Or with a bit of luck will simply not work...
My knowledge doesn't go much beyond Ohm's law, I usually build loudspeakers and not electronic, yet exactly because I need something to tri-amp my forthcoming open baffle I decided to look at a chip-amp, and cheap-amp aswell, for the woofers.
Looking at the data sheet, it seems to me that the slave 7293 needs just the power supply and the connection to pin 11. So I basically connected the two tda pin by pin, with the exception of pins connected as requested for the modular functioning.
In the image you can see the result of so much thinking...
Can you please evaluate if the circuit makes some sense or not and if it has any possybility -with the modifications suggested by you- to work?
Thank you all.

Hello everyone,

A few years ago I built the Frugal Horn. Would like to build a new full range speaker this year, but not quite sure what design to use : ) .
(Previous build https://www.diyaudio.com/community/threads/frugel-horn-mk3.172605/page-89#post-6013616)
For this new build I'd like to use a driver that's a bit bigger than the Alpair 7.3 that I previously used.

I'm thinking something like:
- 1x Driver per speaker: 6-8" driver.
- Budget: I don't really have any limit.
- Something that's not too advanced in terms of build but not just a box either if that makes sense. (hopefully not far too advanced compared to the FHMk3)
- It seems hard for me to find good plywood, so will most likely have to make it in MDF :/ (used 15-18 mm thick last time). If anyone in Sweden has some good recommendations where to find the good plywood I'm listening.
- Size: Undecided yet, I guess it depends on the driver too? I wouldn't mind to have something on some nice looking stands. But it's cool to build something bigger too.
- Something that looks nice, gonna try to get a better finish this time, want to go for something that looks high end!

I've been looking at these drivers https://www.soundimports.eu/en/markaudio-maop-102-white.html coming into stock soon it looks like. Might order those, what do you think?
Seem popular looking at other threads.

I've been looking at the images of the Haruna (FE166En ) and Kirishima (FE206En) (looks easier to build than the MK3 even though it has more parts). They look pretty cool. Would they work with the MAOP 10.2? https://www.frugal-horn.com/spawn.html

Also looked at the some different Onken images a bit. http://frugal-phile.com/boxlib/P10free/MarKen10-1v01-map-090810.pdf for example.

Appreciate any suggestions!

In this thread, I will discuss a concept I find interesting and promising: tandem regulators.

The concept was introduced in this discussion, but it was quickly drowned by a thousand other topics, and I think it deserves better.

• Tandem regulators in a nutshell:
  A shunt regulator normally comprises two elements: the shunt part itself, and a constant-current source (or equivalent function).
  Ordinarily, these two element are completely independent; this means that the CCS has to be dimensioned for the maximum output current the regulator will ever see (+ a regulation margin), and the shunt element will see the full variation of the output current.
  This leads to high dissipation and poor output impedance.
  In a tandem combo, the CCS has its current coupled to the shunt current: this means that variations in the output current will be mostly compensated by an equivalent variation of the CCS.
  The advantages are pretty obvious in terms of dissipation and output impedance.
  Note that the regulator retains its shunt nature: the shunt regulation is the fast, dominant loop, the CCS being just a "helper": if the link fails, the regulator reverts to the ordinary shunt mode.

Let's see all this with an example tandem reg especially designed for an easy comprehension.

We start with a regular shunt reg (first pic). The CCS and shunt regs are easily identifiable.
The power supply rejection is good, a few hundreds µV residual, but the output impedance is less satisfactory (second pic, output current 7.5mA, 5mA pp variation).
Now, let's add a few components (third pic): we can check that they have negligible effect on the initial performances.
Now, let's establish the link between the two regulators (4th pic). The PSR is marginally degraded, but the effect is not significant.
By contrast, the effect on the output impedance is quite dramatic (5th pic).

Another noteworthy effect is that the output current can be increased beyond 25mA without losing the regulation (6th pic)

I was exposed to high quality audio around 1973 when I moved in with a friend Brad in Mission Beach who spent three to four times the cost of our cars (around $500 at the time) on audio equipment. Early 80's I became a budget audiophile doing DIY projects, many pieces comprise the systems I listen to now. I still enjoy repairing and upgrading electronics. So I am here to get info and help others if I can. I don't like posting but prefer emailing or better yet talking. Already I see replies to what I thought was the title to my intro post. Maybe admin can fix this and put it where it is supposed to be in Introductions. Thanks

I have a pair of DI that I made an external xover for. I have since bought the MOABs, so I returned these to stock form with upgraded posts and the lower crossover is upgraded as well. Also better internal wire. I also have the grills for them. I'm not shipping them, so they would need to be picked up here. I do have them setup in my lab, so you can hear them before you buy.

If you are close to Rockford, Il and want to have a listen and make an offer, hit me with a PM. I can get some photos for you as well.

I would say the boxes are a 6-7, but the sound is good perfect. If I can't get $1700 for them, I shall leave them where they sit... I have smaller speakers in the lab, but the DI are jamming in here now and I'm smiling. They had been sitting waiting for me to get around to putting in the original xovers, so I had forgot how sweet they are.

It's pretty amazing just how loud these things will go with 10W. They are perfect for flee watt or SET amps.

I'm playing with the idea of taking a pair of Ikea Blanda bowls, a coax or fullrange driver, poke some holes in it, and cover them with felt and hopefully end up with something like the cardioid ball from Gradient 1.4. What could go wrong right?

The Gradient 1.4 ball have it's vent on the back instead of the sides like most other cardioid speakers.
Couldn't one in theory have these anti-phase leaks on both the back, top, bottom and sides?

Hello all,

I'm looking to build an active pair of PA speakers to be mounted on stands. I've built a couple dozen cabinets at this point, and already have 4 Stereo Integrity SQL 15's loaded in reflex cabs that I modeled and built. They're powered with two Crown XLS 2502's at 2 ohms, so they get around 1,200rms a piece and are very loud and smooth. I currently have a MiniDsp 2x4HD that I tame them with in the various settings I play in. I'm currently using a set of HT-12's from Erich at DIYSG as my tops, but I'm looking to upgrade. My restrictions, limitations, and general guidelines of the build are as follows:

• $3,000 budget for drivers, cab, amps, and wires. I'd prefer to come in under this, but this is the cap.
• Start date on the build needs to be within a couple of months.
• I'll be playing for up to 500 people.
• I'd like for them to be generally very reliable. I'm going to be using them at some important events, and would prefer to not skimp, especially on amplification to avoid failure.
• I want to use high quality drivers and try to match my directivity and everything as well as possible for my own OCD, but they don't have to be absolutely perfect as nobody else will notice.
• The subs I have will play comfortably up to 80hz, so there's no need for these to dip below that.
• I'd like to have a reflex enclosure to keep thermal buildup in check.
• Weight absolutely does not matter. Each one of my cabs for the 15's weigh over 100lbs, so I'm already lugging around quite a bit of gear. It's not an issue.
• I'm fine with a 1.4" CD, rather than 1". The very tip top of the frequencies won't be all that important in this environment. I just want nice, crisp, clean sound with good directivity.

I've checked into Hypex amps already, and they seem great, but I didn't know whether or not an in line DSP setup with 4 separate channels of amplification would yield better or more simple results. Please advise and thanks to all!!!

Here is a link to a good video on YouTube about phono stage design.



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Wanted krell ksa boards, may consider complete amp if there's any out there. Thanks.

Hello, if the two-way passive crossover is originally second-order with tweeter reversed polarity, does converting it to fourth-order ACTIVE still necessitate reversing tweeter polarity? And vice versa for the original tweeter's non-reversed polarity.

Edit - add more info:

In my experience, reversing the polarity of the tweeter on second-order low-pass and high-pass filters resulted in a summing frequency response at the crossover region, whereas not reversing the polarity resulted in a “dip”. Assuming we want to keep the dip in the crossover region, we have to reverse the polarity of the tweeter when using fourth-order active. Is that correct?

Im trying to understand when consider we are using a field coil driver with some flux density being about 1Tesla with Fs of 38Hz and Qt of 0.3 now consider Im quite happy with it as BL product is also high enough but more than that the Qt is as per desired but now in order to reach it with a right voice coil size if its achievable with 1T what is need to going higher flux density in the gap like 1.5T or 1.8T well in that case the Qt will drop below 0.15 or so now isnt that a problem when loaded in the box?

My question is that why do you need higher flux density when you are already reaching the desired target Qt values.

I understand more stiff field but the question is isnt it detrimental to reach very low Qts values especially with woofers or do I need to be happy as Field coils flux doesnt get modulated as its always excited with external DC irrespective of the flux density.

Is there anything that Im missing in here?

I switched to a 4-way system with Audiolense and for this reason I want to sell the FirstWatt B5. Price 800 euros.

Advance warning: this is a long read. If this subject interests you, get yourself a coffee now, or something stronger.

PREFACE
In 2010 I assembled a Tripath TA2020 amp board - the diyparadise Charlize 2, which was at that time considered the best of the TA2020 boards, and the TA2020 was still flavour-of-the-month as budget hifi amplifier.
For power supply I chose the well regarded Paul Hynes PR3G2 13.8V regulator, fed from a conventional 120VA EI transformer.
Then life intervened, and it took me another 7 years until I eventually built up a music server/DAC plus Planet10/MarkAudio speakers, to complete my hifi setup. It took another 6 months to sort out a few earthing/ground loop issues, and for the speakers to fully break-in. I am now reasonably happy with the sound, but the bass is a little over-emphasised, like when a loudness knob is turned up. Also I can't help thinking that the high-end nature of my transport, DAC, and speakers makes my system deserve an amplifier which is more than just "budget champion" status. Of course I've heard the hype about the new budget class D amplifiers such as the TPA3110/3116/3118, and the more recent TPA3255, but my preferred upgrade path is (or was) to leapfrog class D altogether, and go for a class AB amplifier such as the Ranchu/AKSA Quasi-Complementary, or the Apex AX11.

Meanwhile I became interested in building a small boombox-style music system in order to hear my music outside my house, on the deck, without needing to crank up the main system to carry the sound outside.
So I recently decided to buy and test the well regarded (and cheap) Sanwu TPA3118 and Sanwu TDA8932 amplifier boards. I had read the long forum posts regarding improvements to these boards, and I was concerned that my TA2020 was built to a higher standard, thus it wasn't going to be a fair comparison unless I did some basic upgrades to the Sanwu boards. So this is what I did:
- replace the output inductors with Wurth WE-PD 22uH inductors.
- bypass the onboard input caps, then wire IN+, IN-, and GND to 3pin XLR connectors. For some tests, good quality input capacitors (Wima MKP10) will then be wired outboard.
- for the 3118 - gain reduction mod, by removing R27.
- for the 8932 - add more capacitance to pin 12, in preparation for full balanced connection from DAC output transformer.
Power supply will be a standard 19V SMPS, smoothed with a capacitance multiplier from ALLO. The cap multiplier is set to drop 0.1V.
And let me say that these small Sanwu boards are rather hard to work on!


SOURCE AND SPEAKERS
My transport is a BeagleBone Black with Twisted Pear Cronus isolation/reclocking board, mounted directly atop a QuangHao ES9018 DAC with Lundahl LL1684 transformer output stage. This output stage can be configured for unbalanced output, or balanced output, via jumpers. Since there's no DC offset from a transformer, it's possible to bypass input capacitors on the amplifier.
My speakers are Alpair 7 gen3 (fullrange) in Planet10-designed onken-style trapezoidal cabinets, which are designated "dMar-Ken7.3mT".
Since the purpose of these tests was to choose the best amp for a cheaper music system, I thought it would be a good idea to also test with a cheap speaker - and I already have a good cheap speaker lying around - the Micca MB42X, which is sold here in Australia as the "Voll B44".
Test outcomes were the same using either MarkAudio or Micca speakers, but the Miccas revealed differences more obviously.


LISTENING TESTS
1. DAC output unbalanced, via input caps.
First I tried the TA2020, since I'm quite familiar with this setup. As I mentioned earlier my only criticism here is that the bass is a little over-emphasised.
Then the 3118 - more detail, clarity, precise treble, and while the bass was still a little over-emphasised, the music was cleaner. I'm now getting an idea of what the TA2020's alleged "tube-like" characteristic might be.
Then the 8932 - similar to the 3118, just not as refined, and some harshness in the treble.

2. DAC output unbalanced, no input caps.
TA2020 - I could maybe detect just a very subtle improvement. The Charlize2 amp is supplied without input caps, because the designer claims it sounds better this way ... but I must say the difference is barely discernible.
3118 - a very small improvement in clarity. Bear in mind that the input caps in the previous test were quite good quality, and they don't seem to impede SQ by much.
8932 - does not work in this configuration.

3. DAC output balanced, secondary centre-tap to GND, no input caps.
3118 - ah, the over-emphasised bass is now gone, with a nicer tonal balance, and a clean, balanced sound.
8932 - does not work in this configuration.
TA2020 supports unbalanced inputs only.

4. for 8932 ONLY - unique connection from secondary centre-tap to amplifier pin 12 (input reference voltage)
Similar to previous result with 3118 - nice clean tonal balance - but occasional harshness in the treble remains.


RESULTS, CONCLUSIONS
I consider myself a rational sceptic, and I was never convinced by the hyperbole surrounding the TPA3118 and TDA8932 - specifically that their SQ eclipsed all that came before, including the TA2020.
But now I'm happy to concede that they are, indeed, better than the TA2020.
The 8932 is definitely in 2nd place behind the 3118. There are comments on this forum that the Sanwu 8932 amp board can be improved by cleaning up the voltage applied to the analogue supply pin, so that its SQ then leapfrogs the 3118, but I can say that presently the Sanwu 3118 sounds nicer than the Sanwu 8932 board.
UPDATE: just today I see an optimised TDA8932 board emerge on the forum! It will be interesting to see how it performs.

Balanced configuration with the 3118 is a clear winner in these listening tests ... but wait ... I don't suggest everyone with a 3118 amp should rush out to get a balanced DAC! This result should be seen in light of my particular situation - I have a transformer output stage with a specific configuration. Sure, you might expect these class D amps to sound slightly better using balanced input compared to using unbalanced input, but I don't imagine the difference to be as stark as the difference that I heard. No, I think this difference is more due to my DAC transformer output stage - I think its performance/characteristics are starkly different between its balanced and unbalanced configurations. This may be related to the topology - my transformer has a filter network on the primary side tailored to suit the ES9018 DAC.

On a related note, over in the TPA3118 forum thread I see it's popular to use an input transformer in unbal-to-bal configuration instead of input capacitors. This is similar to my situation, but not the same - especially in terms of the aforementioned filter network of my transformer. So it makes me wonder which aspect(s) of this input transformer achieve the apparent improvement in SQ:
i) using the amp in balanced input mode instead of unbalanced input mode?
ii) eliminating input caps? (in my tests, good quality input caps don't hurt the SQ of the 3118 very much)
iii) adding a transformer flavour to the sound?
iv) a combination of the above?


WHAT NEXT?
To get a better idea of the different quality outcomes of using unbalanced or balanced inputs of a TPA 3118, it would be useful to employ some form of output stage OTHER than a transformer; say a solid state device with switchable unbalanced/balanced outputs. Or maybe the direct output from a PCM5xxx DAC chip. The PCM5122 is unbalanced, and the PCM5242 is balanced. And both have no DC offset, so you can go cap-less into the amp.

But I've lost interest in any further tests at this stage. Winter is closing in, and building a 2nd system/boombox has fallen down the priority list!
For now I think I will probably swap out the Charlize TA2020 amp in my main system with the 3118 amp - and obviously connect the new amp in balanced configuration.
Can I be bothered to box up the 3118 boards in a nice chassis? Probably not. This generally ends up taking more time than you expect, and also I need to take some time to consider my next step with the hifi system overall. I now know that my source device is (significantly) better in balanced mode, so the unbalanced class AB amps I was previously considering are now probably off the list. If I stick with the TPA3118, maybe I should get one of the "premium" boards such as the newly released one from ALLO? Then again, current flavour-of-the-month seems to be the TPA3255, or for my fullrange speakers maybe more suitable would be its lower power brother the TPA3250?
And then there's the TPA3244 - I don't think anyone here has heard this amp yet?

Must sleep on it.

Recently received a 350W custom PT. I spec'ed it out for 115V primary, but it came with 220/230V primary instead. Cannot use this unless I run extension cord from laundry room- lol. I see from research here that primary is most likely first winding, so is there easy (or relatively easy) way to modify it- ie separate into 2 equal windings to operate in parallel for 115V operation? Or should I sell it and take the loss?
Thanks,
Jim

Just wondering if anyone's got a leftover pair of Pearl 2 PCBs laying around? Preferably without the JFETs (as I already have those) and from an EU-location, but let me hear what's out there 😎

I would add to that, reasonably constant directivity above 1kHz, with 90-ish deg beamwidth in the horizontal plane. HD products restricted to the audible range.

I'm not well versed in horn-loaded designs, but I believe no such combination exists that's commercially available? For all I know, the limitations imposed by non-linear acoustics may prevent such an outcome...

Thanks.

Hi, my active crossover, a/d/s/ 642ix, can only be adjusted filter frequencies by changing filter modules. It has instruction for modifying these modules. They also had provided table of modified values. Please find attached pictures. I’d like to have the low-pass filter frequency to be at 320 Hz. Please help me to calculate component values to achieve 320 Hz. Thanks in advance

I have for sale the above amplifier in mint conditon given its age.

This model was designed for Clair Bros & features a pressed steel chassis and was used by Jands Production Services.

The amplifier has been fully maintained throughout its service life.
The Phase Linear 700B Series 11 produces a conservative power output of 360 watts into 8 ohms per channel, the threshold of clipping being 450 watts per channel.

The amplifier for its vintage and design produces excellent measured and subjective performance. I know longer have a use for this amplifier.

This sale is only available to residents in Australia.
The price is $700.00. All shipping costs are paid by the buyer.

Please send a Pm if you are interested.

Ian

Diyaudio Pass F5 Boards for sale, currently out of stock in the store.

£10 plus shipping at cost

Here's a schematic of the XO for the Heybrook HB2's -- the woofer for this one was destroyed by too much teenage activity so it is in the woofer replacement facility -- why is R1, C2, L3 connected to the tweeter "+" ? when I simmed it I note that it "shelves" the response. The tweeter seems to be the standard, government issue Audax 1"



Here's what the actual response into a resistive load looks like:

I'd like to take some acoustic measurements outdoors. Eg. empty basketball court, football or cricket pitch. Bringing a laptop to power the audio interface and microphone is great; only thing that needs AC power is the test amplifier.

So I'm looking for battery powered amp that can output approximately 1-16V into 4 ohms (~50 into 4 ohms).
Ideally self-enclosed, has audio input and speaker output connections.

Mono is fine. I get that this is a DIY Audio forum and people like to build their own, but right now I just need to collect measurements from loudspeakers.
The most I would like to do is to connect alligators clips to a SLA to a DC-input based TPA3255 based amplifier, but before I do this, is there another solution that people have used?

A friend was over the other day to recap his crossovers. I have a solder sucker but it really doesn't clean out all the old solder and we had a hard time removing all the solder. Then I remembered this little tool I use to clean out my gas welder tips.

I could pass these tiny round files through what little holes were left after we cleared out the solder.

Works really well and easy and they are inexpensive

Wires not cut!
800$ incl. shipping!

Regards, Klaus

I'm in the process of putting together a system with a Audio Sector Gainclone kit and a Pass Labs B1 input buffer. My main sources are a phono pre and a CD player. I will also have a mini jack input for my ipod or computer output for streaming audio such as Rhapsody or Pandora. Both my ipod and computer have a pretty low output. I want to be able to match the gain on that input to the level of the CD player which has nice output and the phono pre that has a gain control. I'd like to have all the levels equal before they go through the selector switch and then into the B1.

Is there a simple gain stage circuit with a pot that I can run the ipod/computer through to give it a little boost to match the rest of the sources?

Thanks, Scott

In many thread in this post I see some people asking how to control the volume/voltage of a line level signal. In many cases, people recommend using a 10k potentiometer (optimally it should logarithmic but let's not take this into account right now) as a voltage divider connecting the left pin of the pot to GND, the middle pin will be the line level with its volume decreased and the right pin would be the line level.

Some people says it works just fine, but I am wondering here: the line leve spec recommends using a 100 to 600 ohm resistance in the line out level. Using the 10k pot as above, would result in a much much higher resistance.

Also, many line inputs have already 10k ohm (or even 100k) resistance so using a 10k ohm at the line output shouldnt be a good idea (I dont know why, but I think it shouldnt be correct).

So I ask you guys: why most people recommend using a 10k ohm potentiometer at the line level out? Wouldnt it be much better to use a 1k ohm potentiometer since you would be much closer to the spec (600ohm) and much further away from the 10k-100k resistance of most line input?

I've read a lot of DIYaudio posts but haven't posted much myself:well here goes. I got into vintage tube radios about three years ago and that lead me to a Harman-Kardon tube AM-FM receiver. This dude weighs like 40 pounds and has twenty tubes; it will heat a small house but I love look and sound of this vintage of gear. I have gone through this receiver and brought it up to specs but I m having trouble finding power tubes (7355s). I have been able to find un-matched 7355s but it really needs a matched quad to perform as designed, and they are not available. I did some research on a replacement and the closest pentode to a 7355 currently in production is the 7591. 7355s and 7591s operate in push-pull at pretty similar voltages except the Grid #1 voltage, which are -23.5 vs -16, respectively. So how do you change the grid #1 voltage? H-K brings the cathode ground up with a voltage divider circuit that also drives the filaments of three pre-amp tubes instead of having true negative dc. And to boot, on my unit, the aforementioned filament voltages are low (8.9, 8.5, 7.6). Instead of trying to make a new divider circuit, I decided adding a new power supply would be the answer. The new power supply has an adjustable negative dc for grid #1 and powers the pre-amp tubes at 12.6 volts (±10%). The bonus to having an adjustable -dc is I can properly bias either 7355s or 7591s. I have completed step one, which is to install the new power supply, re-power the pre-amp filaments, connect grid #1 circuit to the neg dc supply, and connect the cathodes to ground. I haven't modified the tube sockets yet so I brought it up today with 7355s and it biased very easily and performed very well. I wasn't sure what effects the increased filament voltage in the pre-amp and increased plate to cathode voltage in the power tubes would have, but i'm happy to report no new hums and a slight increase output, particularly in the phono pre-amp. I attached the schematic of the mods. The only modification left is to decouple pin 4 on the power tube sockets, and put a jumper from pins 8 to 4. After the sockets are modified, I'll try try to bias a new matched quad of re-production Tung-Sol 7591s power tubes and report back. Thanks for reading.

Bill

Hi Folks,

I think this might be my first post here, so please go easy. I recently completed a Martinnson ROAR12 build using a Beyma 112nd/w. It simulated quite nicely in Hornresp






The build was easy enough, but the results were somewhat interesting. The intended use is a small PA for my farm and as the bottom end of a bass guitar rig.


I am fortunate enough to be able to measure in a paddock 100+m from anything reflective. The results are as follows (uncorrected SPL) -



The efficiency is simply ridiculous at 100hz, but the low end is rather disappointing. 45hz is some 15db down on 100hz. It still outputs a surprising amount of noise at 45hz, and a simply ridiculous amount of noise at 100-150hz. The 1w/1w efficiency at 100hz works out around 110db and if I eq this out, the woofer seems to run out of excursion down low.

I have read some threads where the merits of the ROAR design were questioned, but not resolved.

Has anyone built one of these and has similar results? Is there a likelihood I have stuffed up something in the construction, or is it more likely that those questioning the design and simulations were correct?


Any input would be appreciated.

Lax

Well MTM minus the T 😉
for you speaker building guru's I'm curious to know, does it work OK to use two full range drivers per cabinet to raise the sensitivity?
You have to do sim's, and modify the cabinet or can use the same cabinet design for the given driver?
Spacing between the drivers is critical?... I assume adds another complexity to figure out or experimented with?
What about if the drivers have a whizzer cone, does it matter, and can it still work?

Dave, has anyone tried this with the Frugel horn or other cabs?
a quick search found this about dual drivers - I will edit this post as I find more ...
http://www.planet10-hifi.com/downloads/Dual-Driver-Wiring.pdf

below I added a speaker designed by Omega sold by Decware - so I guess it works.

I built myself a 'spud' headphone amp a few years ago that's nothing more than a 500VCT power transformer with full wave solid-state diode rectification, CLCRC DC plate supply, 6.3VCT (AC) heater supply, two 12HL7 pentodes wired triode, a pair of Edcor 8k:50 SE OPTs, and the usual complement of jacks and a volume control.

The 12HL7s are being run pretty hot, at about 150V plate-cathode and 45mA Ip, so Pdiss is almost 7W. That's an attempt to keep the rp down low to compensate for the not-very-generous primary inductance of the very cheap OPTs. The max combined plate+screen dissipation for 12HL7 is 11W, so I figure 7W is low enough that the tubes should have a decently long service life.

Being that it's a headphone amp for bedtime listening, I sometimes fall asleep and leave it on overnight. Sometimes I forget to power it off when I get up, so it stays on all day.

I find that the 12HL7s go noisy after about a year and a half of use. One or the other of them will start to crackle, which is horribly uncomfortable in headphones! (Ouch.) My question is, should I expect these touchy high gm RF pentodes to go noisy after a year or two of use, or does it sound like something is wrong and I should start looking for a problem?

I have 1k ohm grid stoppers on the 12HL7s and 0.1uF 100V film caps bypassing the heater supply to chassis. Perhaps there are more oscillation suppression steps I should take? 10 ohm plate stoppers?

There is a critical design update here:

http://www.diyaudio.com/forums/digi...sic-pass-labs-d1-ess-dac-173.html#post3662046

Please read this before ordering any parts!!!! I will update the BOM attached below at some point and see if I can have up replaced.

Hi Guys,

This will be the official build thread for the I/V stage PCB group buy. Please post all build related questions here.

Also, feel free to post pictures of your build, chassis ideas, parts suggestions etc...

I'll start things off with a final schematic and SMD BOM which people will need for the build. I'll have a BOM posted for the remainder of the PTH parts, and it will include all the parts I used in my build.

Cheers,
Owen

I been lurking on this forum for a while, learning from the kind and knowledgable folks here. Thank you! Years ago, I built MLTL bass boxes based on a design of Paul Kittinger, using Martin King's programs. Loved it!

Now, I'm inspired by the Pensils and Sebelius to design and build an MLTL tower using Alpair 10.2's. To fit in my space, I'd like the cabinets to be a bit smaller than the Pensil. The first diagram gives the general dimensions. I did a bunch of modeling using Hornresp. The pictures show the model parameters I came up with. The modeled response looks pretty good to me, with a bump ~42hz. Mouth velocity is a little high near the driver x-max. Otherwise, I would have make a narrower shallower port. Did I model this correctly?

I built a test box and measured it. The test box is slightly larger than the model to allow for some adjustments. But, it's pretty close. The driver has ~150 hours of break-in time. The near field measurement look pretty good. And it sounds pretty good! The bass is extraordinary for such a small driver.

My first question is about the FR chart dips in the 100hz-200hz range. Some were measured at 3', others were measured at the listening position of 10'. Is this floor bounce (carpeted room)? Rear wall bounce? A gated measurement problem? Poor cab construction? Interference due to distance between the driver and port? Should I do anything about this?

My second question is about baffle step compensation. I find that the speaker sounds more natural with a ~2db baffle step shelf starting at ~1khz. Have any of you found the same? Do you think building a full-size Pensil would increase the low end and midrange enought to avoid the need for baffle step compensation?

Any advice would be appreciated!

ALTEC LANSING 414-8B pair - NEW wrapped in plastic/boxed -- $999 USD OBO
411-8A pair -- used -- $999 OBO
Horns 511B pair -- NEW no screw marks, etc -- $500 OBO

All in original boxes

Prices are for pick-up
Shipping might be possible, depends mostly on price and payment

What's the difference in noise performance of two triodes in parallel ( Anode, grid and cathode connected directly in parallel ) and one with a common anode load and separate cathode resistors with bypass capacitors ?
Unless the sections are very closely matched , the direct connection will not ensure identical operation of the two sections. Which is a better way to operate in 'parallel' ?

Conrad Johnson had a design with 12 tubes in parallel. How did they do it ?
IIRC some designers claim that parallel operation of tubes ( or even SS chips) sound worse than single device operation.

Is this observation confirmed now ?
Cheers,
Ashok.

can somone please send me a schematic diagram for a pyramid 1800x amplifier >

First, let me automate the inevitable debate that will follow. This is in C code, which is almost as old as the Bose Co. itself 🙂

FlameWar(void)
{
while (TRUE)
{
printf("Bose sucks!\n");
printf("No! Bose rules!\n");
}
}

Ahem! Moving right along, Soldermizer has been main-tracked, actually working on relevant DIY stuff the past few months. He just built a shelf unit for his garage. Something actually practical for God's sake! This is very out of character for him. However, his motive is pure: he now can more easily store his paint cans for his continued "faux [pas] finish" interiors, wood graining his '09 Suzuki (yes really, looks pretty good...) and water marbling with oil paint (fun and very messy.) Now what, you ask, does this have to do with Bose? Damned little to be honest, but here goes. The point is that Soldermizer hasn't devoted the usual amount of time he usually does to idiotic stereo ideas. Thus today's installment.

Everybody who knows Bose usually "knows" the first product was the 901. Not so. Two years prior was the very odd 2201. This was if I remember correctly, a pair of 1/8 sphere speakers. Each was a polyhedron of 22 active (and individually EQ-ed?) drivers. Bose was attempting to re-create a sphere diffusion or some such idea. I think he later abandoned this idea, but ... did he, or anyone else, do further research on it? Could it be that the dear Doctor, before he devolved into that phenomenally successful marketer and arch nemesis of audio snobs everywhere , was actually onto a valid concept he abandoned too soon, you know, sort of like Tesla* giving up on his time machine (kidding!)?

Is it possible that he did not have enough technology in 1966 to adequately build his speaker? In 2015 China sells us more than fireworks 🙂 Four dozen (small) amplifiers and the same amount of DSP filters are within the budget of many experimenters.

This would be a fascinating area to research, even if just in the literature. Anybody ever heard if this sphere idea was developed further?

*We should all be thankful to Tesla and his discoveries. If it weren't for him, we would not have AC current and our speakers would really sound like crap with only DC current 🙄

Selling 1x pair of Markus Klug wooden horns for Altec 604/605

Longer screws included

SOLD

I'm curious what if any small bookshelf/desktop full-range no-crossover speakers are there with decently high sensitivity
(say 91db/1w or more) that are for sale retail?

-- SOLD --

1pair TAD TD-2001 H.F. Compression Drivers
New in original packaging, opened for test fitting and photos.
$2,000 for the pair
Shipping negotiable world-wide

will throw in B.Edgar 650Hz Tractrix wood horns if wanted, but one mounting plate is missing 🙁

I'm trying to repair a ribbon cable in my MacBookPro. It carries the power for the display back light and the ribbon has cracked, a known issue. The local Mac store want $600 to fix it, and new display with cable is $250. The cable is not replaceable. That's why I'm attempting the repair.

So far I've made decent progress scraping the insulation off the cable, tinning the tracks and almost getting it repaired with thin wire strands over the tracks. But as you can see from the photo below, I've got too much solder on a couple of tracks and it's bridging where there shouldn't be a bridge. I'm having a very hard time removing the excess solder. The work area is small, about 4mm across.

Chemtronics solder wick size #3 is somewhat too wide and thick, it's not sucking up the solder. I don't have a solder sucker.
Melting the solder and flicking it off with an Xacto knife isn't working, the solder stays put.
Solder is Kester SN63PB37 0.02" diameter.

Anyone have an idea for getting these solder blobs off the traces so that I can start over?

This is one hell of a long shot, but i'm getting somewhat desperate, so here goes.

I recently got myself an ancient knockoff of an AKG P820 tube mic from a local store brand, per the service manuals, at least the PSU is a direct 1:1 copy. Now, the PSU appears to be dead, the T125 fuses blow instantly and the light never comes on, this model is basically wholly undocumented but there is one forum post from 2012 that indicated a possible faulty transformer. Upon desoldering the transformer to take some DCR and impedance measurements off the crusty board, i promptly lifted all pads. That, combined with the no-name unspec'd transformer and the generally subpar parts, have given me the idea to just design a brand new PSU basically replacing everything except for the pattern selection section. So my question is, is there anyone that'd be able to help me figure out what kind of voltages i'm looking at so i can get started? I will post pictures and link to the service manual in a couple of hours when i get home from work.

(I have contacted both the store that used to carry them as well as AKG and it would seem i'm SoL as far as getting original parts, despite the AKG variant being a currently available product, i'd frankly prefer an improved self design version anyhow)

Thanks for any help!

BMS 12N630 12" Neodymium Ultra Low Distortion Woofers
8ohms, 600W

2 pairs available
$500 a pair + shipping

Selling a pair of Elrog ER300B tubes

They were bought December 2021 and have about 400hrs on them.

SOLD

Hi, What do you think of the TDA1514a regarding audio quality? Is it lower or higher than LM3886/TDA7294?
Thanks

I fell over Robert Jenkins WEB site offering PCBs of this JLH design from the schematic on Paul Kemble's site.

It's something I'd have built from the Hart kit at the time if I'd had the money, so I thought why not, scratch an itch, and sent him an email. No response. Tried again some time later, still no response.

Anyone purchased any or had any contact with him?

Hi friends

This is an embarassing question: What is the orientation of the backside's drawing (with the motor's connection pins) in the datasheet (see below)? The pot's connection-pins downwards I guess? (So, looking at the pot's back with the pins downards oriented, V+ is on the right side?)


I kinda think it's either way and can be just tested (swap the wires if it doesn't work), but I'd like to have it confirmed because I have a little issue here (motor's not turning although everything else seems to work), and it would be comfortable to have one variable less...

Thank you

Hello

I have a Pyramid power supply which gives 13.8V . I adjusted the pot inside the PS but can get near 13.2volts at lower point. I want 12 volts to feed a Mac mini. This circuit seems interesting because it uses discrete parts instead of ubiquitous 78xx with a pass transistor. Any other mods suggestion ? Thanks

I have 2 Tubes with 50 pieces Caddock MP930-0.25R-1% thick film resistors without use .

I’m asking for 1 tube / 50pieces €75

Power Rating: 30W with Heatsink / without 2,25W

• Product Range: CADDOCK - MP930 Series
• Resistance: 0.25ohm
• Resistance Tolerance: ± 1%
• Resistor Case Style: TO-220
• Resistor Element Material: Metal Film
• SVHC: 27-Oct-2004 & 26-April-2004

Price + PayPal 4% + register shipping expenses. Shipping form Finland

Rgds
Finwbu

Hopefully this one is a little more simple. Rockford Fosgate 250a2 PC-2035-G. Typical blown channel, but when I went to replace an open source resistor I noticed they are 0.03 ohm, not 0.1 ohm as I'm used to seeing. Also, R261 & R235 are 0 ohm jumper "resistors", and R262 & R234 are excluded. The amp hasn't been worked on before, and matches another 250a2 I looked at.

The main issue is I don't see much available for 0.03/30mOhm 3W 5% resistors. If I changed to a 0.1ohm source resistor, would I restore R261 and R262 like the earlier revisions? I only have schematics for Rev B & Rev C, which show 0.1 ohm source resistors and R261 as 20 ohm, R262 as 10 ohm. The IRF540 side of the 200 channel is the only damage (inc/R252, Q216, D204). Would I do the IRF9540 side as well?

Hi , I recently bought a Audio Research LS15 tube preamp that is working and sounds very good. It has an issue though. It after it has been on for a while say maybe an hour It automatically shuts off. turning it back on it will work for a little while then shut off again. I bought it knowing this and without knowing how the unit was designed initially thought maybe it was a just a cold solder joint or a crack in a trace maybe a wonky tube socket.
Upon receiving it i discovered that front panel controls are not analog pots and switches but digital and are handled by a 8-bit microcontroller and a couple 8-bit shift registers. In the manual it warns that static discharge could potentially lock up the MCU and require a restart. That got me thinking this is a older unit circa 1998-9ish and maybe the electrolytic caps are out of spec and when it heats up for a while maybe voltage fluctuations are causing the MCU to switch the unit off?

I figure maybe the best course of action is to replace all the electrolytic's and then go from there?
My question is there are no electrolytic's in the audio path just in the PSU and MCU sections , They are all Nichicon VX(M) series caps except the two 470uf (M) 200V main caps which are SMH series snap-in types, all are out of production. Can anyone tell me what series caps would be suitable as modern replacements? They are all temp rated 85c, would it hurt to be looking at 105c? One of them on the underside of the circuit board is a 47uf 250v polar Axial which i don't think is made anymore. Could i just lay a radial type on its side and end the leg over the top? Thanks in advance for any help.

I have an excellent probably 20-22 year old, 211 SE amplifier rated at 18W per channel. I use it to drive my mids/tweeter D'Appolitto speaker. The amps designer is no longer with us. In September of this year the amp developed a ticking sound in both channels, not loud but when you get close to the drivers you'll hear it. If I put my lowther PM2a in then it is loud (ticking) as expected from a 97db speaker. The odd thing, to me, is that the bass driver which is driven by a 200W solid state amp also ticks, and this stops as soon as I turn the tube amp off. I am pretty confident the source is the tube amp and probably some old, heat affected components like plate resistors, resistors in the 211 filament circuit, possibly old electrolytic caps, after all the amp is 20 years old and throws some serious heat.

I have attached a schematic which the designer sent me a few years ago, I highlighted in yellow a capacitor in the filament circuit of the 211 which calls for a 3.5uF, 100V capacitor. In reality installed is a 1.25uf, the K I believe is 10%, 100V MPC style. I am not a technician but does that look ok to you 1.25 installed vs. 3.5 schematic. Also at the amps input I have a texas component 1K bulk metal foil resistor which connects to the grid of the 6sn7, also, according to the schematic a 200K ohm resistor runs from the grid side of the input resistor to ground. Installed in the amp is a 79K ohm resistor, not the 200K. Is that an issue?

I replaced the plate resistors (15K and 12.5K) earlier this year with mills MRA 12 resistors (15K and 12K) and earlier this week rechecked my soldering to make sure I had good joints, so hopefully these are not the cause. Visually looking over the components the 1K resistor in the 211 filament circuit looks a little heat beat up and the board below a bit brownish, I have 10W, 1K vishays on order to replace these. As stated in the title the ticking does not start until the amp has been on anywhere from 2-5 hours. You can see this 1K resistor right in front of the yellow capacitor in the attached photo.

Basically I am looking for advice on what you think could be the most likely cause of my ticking and if the 2 cases I note above are fine (they probably are) as is or should I revert back to what the schematic says. The components mount on vector boards with swaged terminal posts and these can be wired from the top or bottom. Things can get pretty tight in there, so soldering to these is not the most fun thing to do. Should I just replace some older components just because they are old and if so what priority should be given?

Thank you!!

Hi all.
I have been reading conflicting arguments when it comes to fuse sizing for transformers. Especially when it comes to smaller transformers say <25VA.
To complicate things further some manufactures include a thermal fuse in the windings.
Reading some of Rod Elliotts articles suggests that smaller transformers can’t be made safer with the use of external fuses. I still can’t understand why he says so. Maybe someone can explain?
I have opened up many wall wart type packs only to find no fuses and sometimes only thermal fuses. What if i find a replacement transformer that has no thermal fuse?
I do mainly repairs and want to give my clients the assurance when having to replace a transformer in their gear.
Thank you in advance all!!

Hi,

I know DIYhink sold one, but are you aware of such things in Europe ? Basicly a three I2S output for a 3 ways active loudspeakers

Well I can buy too a Behringer UMC1820, but I have already three stereo dacs that just need to see each an I2S.

something like that : https://www.diyinhk.com/shop/audio-...et-type_c_new_and_slim/159-esd_protection-2kv

thanks

Its about time we gave this one a thread😉

I just build a stereo amp using two NC400 modules, a SMPS1200A400 and the connection kit



Im using the Amp Enable pins in the board to connect both NC400 nAMPON wires, but for some reason, Im getting a slight turn-on pop on the speakers. I've read some other builds not using this PCB and they state that the amps have no pop whatsoever and Im wondering if this pop is the result of using this board.

Here is a pic of my current build

Hello,

i wanna share with you quite a strange story
i bought the Presonus Eris E8 quite a while ago (like in 2016) and was blown away by the piercing high frequencys (and the otherwise really good sound), well the -2 to -4db highshelf eq helps that get spoken about quite alot on the web for the Eris but it kept me curious how sound engineers can bear the sound while working since they are studio monitors and they should be used "flat" for that purpose
i even send them back to thomann who measured them, all ok but i kept going and send them back to Presonus directly and got a new pair since i thought they are defective in some way (well ... my first "good" speakers and no clue about audio at that time)

well, since then i lived with the EQ setting on the back of the speakers for -2 to -4db high frequency reduction and since i use CamillaDSP in moode i Eq`d it there

fast forward, since a few months i noticed that
A. my left speaker/tweeter isnt happy with some frequencys, in layman terms it sounds like it "breaks up" or clips or something even if i just listen at about 75-80db still unsure what it is but for most music it sounds fine, sinus sweeps sound perfectly fine too! (please let me know if you have a clue)
B. the right speaker isnt happy with some low frequencys, i think its the resonance frequency of the speaker itself, something rattles inside if the right frequency gets hit

now i found recently a good song that hits the right frequency with each bass and thought "lets look inside" maybe something loosed up or something, everything was fine so i thought maybe its the cables to the speakers that rattle against something, so i took some cable ties and remanaged the cablemanagement inside and where the tweeter and woofer cable where tied together in the first place, i actually seperated them, i listened and HUH the high frequencys sound much better now.... so i also did this mod for the left speaker and yea, improvement overall in the high frequencys, i was even able to turn the EQ off, well i ended up just reducing the high frequency reduction to around -1.5db where it was before -2.5

Now im questioning myself a bit, is it even possible that the high frequencys sound worse if the cable of the woofer touches the tweeter cables? is it some kind of "overspoken" signal? and if yes why the hell the manufactor decides to tie them together?

Curious what you guys think! and maybe you can help me with the tweeter problem in the left speaker that sometimes i think also apear in the right speaker but by far not as worse, is it maybe just what we call in german "Klirrfaktor" ?

I’m interested in building an F6. I’ve only recently begun looking at some of the information available here and it seems like a fairly straight forward process. I would be using parts from the diyaudio store. Do these parts replicate the Pass design accurately enough? I just want to be able to duplicate the amp exactly as Pass intended. I’ve successfully built a pair tube amps and a preamp from kits as well as a pair of speakers; a Dick Olsher inspired Basszilla Platinum. While I feel confident in my soldering skills and identifying components this looks a bit more demanding. This amp will replace a 20 year old SS Marantz ht receiver.
This is a a great forum. I look forward to your help

Never got around to doing anything exciting with these. Purchased from a UK source. Legit Maxwell supercaps.
8 off for £30 delivered UK. Rest of World please ask.

The speakers themselves are normally 3-way. If I use an active crossover to filter low-pass signal at about below 100Hz and feed it to the amplifier that drives 3-way speakers. Could it be considered as a 3.5-way system?

I have 4 of these boards available. 1oz copper as I don't intend to be using anywhere near the 5A capability.
£3 plus postage
Thanks

Finished a phono preamp build. Used a cheap EI transformer to generate the AC voltage needed for the +12V/-12V. When I powered the preamp up I got hum. After some troubleshooting I decided to power the preamp with two 9V batteries, bingo no hum!

Next thing I do is energize the transformer but leave the secondaries disconnected. Testing for hum that is being coupled to the audio signal. Doing this I got hum again.

I added an IEC filter as I suspected there was some DC on the incoming AC power line. This helped a great deal with the hum but some still persists.

What can I do to minimize the hum now? I have lots of copper shielding tape left over from shielding a guitar. I don't really want to go buy a toroidal transformer.

Here is a pic for reference (click to enlarge)

I decided to highlight this scheme as a separate topic, because a concept has been formed both in terms of topology, element base, correction features, and, in fact, sound.
This scheme was called Fury (FURY).
circuit features:
1) the circuit of the voltage amplifier on JFET transistors in cascode inclusion
2) two NFB circuits, one of which covers the output capacitor, the second also corrects the stability (taken from the output of the amplifier)
3) complementary hexfet output
4) deep NFB (not less than 70dB)
5) inverting inclusion

The block diagram of Fury consists of three stages:
1st cascade on the field (jfet) with inverting inclusion
2-nd cascade of field devices (jfet) with dynamic load and low-impedance output for coordination with output stage
3rd cascade single follower with high-resistance input and with dynamic load + push-pull output stage on hexfettes in class AB
The nuances of the scheme:
* the first two stages without load have a gain of 95dB
* The contour of NFB at the input determines the overall gain of the circuit at 19.2 dB
* maximum input voltage (amplitude 3 volts)
* added RC input f = 816kHz to reduce dynamic distortion
* the second NFB circuit goes to the gate of the second stage, it is connected relative to the reference voltage of 13 volts (implemented on the zener diode), this circuit carries out correction of the amplifier at high frequencies for its stability and sets the operation mode of the output stage by constant voltage.

P.S. In the event of a break in any of the negative feedback loops or two at the same time, the circuit remains operational.
Nuances of the scheme of the 3rd cascade:
* at the input a field + bipolar transistor, which takes a signal from the source of a stable current source, because lower pre-amplifier output impedance is needed to match these stages
* dynamic load performed on mosfet IRF510
* The bias circuit of the output stage is made on the BD139 transistor with the IRF530 transistor - it provides smooth adjustment of the initial current of the output stage 100mA
* The thermosensitive element is the BD139 transistor, it is he who is screwed to the radiator.
* The use of IRF630 / 9630 turned out to be quite a musical complementary pair ...

Circuit Parameters:
* Ku = 19.2dB
* Uin max ~ 3V (amplitude), Uin nom ~ 2V (amplitude)
* P out (RMS) max = 40 watts (4 Ohms)
* slew rate SR = 5.84V / microS
* Frequency response in the frequency range 1-100000Hz is 0.05dB
* uneven phase response -1.5 degrees (20 kHz) and -7 degrees (100 kHz)
* delay at a frequency of 100 Hz - 0.24 microS, at a frequency of 20 Hz - 1.4 microS, at a frequency of 5 Hz - 96 microS
* output impedance R (i) 0.34 ohm ...
* the depth of the negative feedback in the frequency range 1-1000Hz is 76dB, at a frequency of 20kHz - 70dB
* THD distortion (nominal) at a frequency of 1 kHz less than 0.001% (0.0004%), at a frequency of 20 kHz - 0.006%
* initial current of the output stage 100mA
* power scheme - you can use unstabilized

Hi,

I need a pair of 2SK3497 for a J2 build.

Thanks,

Marijan

I created this contraption 40~45 years ago, but since it is just ordinary, run-of-the-mill circuitry combined with a lousy implementation, I never cared to publish it before.
However, even though the implementation is unremarkable and completely outdated, the principles are sound and could be reused in a more modern reinterpretation.



The principle is simple: a mechanical probe (a strip of spring-metal) is swept across the ridged surface to be analyzed. The probe is in contact with a piezoelectic sensor, which generates a sharp pulse each time the probe jumps from one peak to the next one.
The pulses are shaped, filtered and counted after being subjected to hysteresis to remove false/double counts.
This oscillogram shows the signal at the input of the schmitt trigger when the probe is swept quickly through a M4 threaded rod:



The pulses are accumulated in a two-digit counter, which limits the maximum count to 99, but in practice it is usable to ~200: it is easy to see if a winding or a thread has more than 100 turns, and in this case if you read 35 for example, it means that the actual number is 135.

The circuit is slightly more complex, to take into account the realities of such measurements:



When you prepare yourself to make the test, you generally have both of your hands busy, but you need to push the clear button and then place the probe in contact with the object you test, without accidentally touching something else, or landing too roughly on the surface; in the meantime, you have your gaze focussed on the work area, not on the counter, and you may miss an accidental count or two.
To prevent the situation, Lachesis is fitted with a rudimentary sequencer: when the "Start" surface is touched or brushed, a timer is initiated, providing a 6-second dead-time before any count can be registered.
When the 6 seconds delay is elapsed, counting is allowed and the status is signalled by a red LED and an (optional) acoustic signal.
The active phase lasts 90 seconds, and its end is signalled by the green LED and the muting of the audible signal. The probe can then be safely removed without risking to alter the total.
The tester can also operate in a completely manual manner.
The schematic is not fully detailed, as it would make little sense: even if someone wants to duplicate exactly my build (this would make little sense), it would be very easy based on the datasheets of the IC's used.

This is the probe:








It is pluggable, but in fact I never built another one.
The piezo element was salvaged from an old PU cartridge, and inserted into a silicone sleeve. The sensing element and the spring strip were then inserted in a common silicone sleeve and pushed inside a brass tube:



The silicone provides the elasticity, the mechanical linking and the damping. IIRC, the metal strip came from a razor-blade, and has a thickness <0.1mm, setting the maximum possible resolution.
With this particular piezo element, the open-circuit voltage exceeds 10V and does not require amplification.
Other models could have widely different outputs.
An electrodynamic sensor could probably be used too, with the right signal-conditionning.

A modern version would be based on a µcontroller, and have loads of additional bells and whistles, but even this rudimentary version is useful, especially for people like myself: when something goes wrong during the winding process, I tend to concentrate on the problem and lose the count as a result.
When this happens, a quick sweep provides a definitive answer (sweep 3 or 4 times, for confirmation, like for a bank-note counter)

Today I did some measurements on the B&G Neo3W and Neo3PDR. Biggest differences:

- Neo3W has approximately 3 dB higher sensitivity
- Neo3PDR has better dispersion in the top octave
- Neo3W has a smoother transition from dipole to beaming

EDIT: too bad, the pdf is too big to upload. Try this link: [removed link]
I hope it works.

EDIT2: apparently not too well. I'll have to try something else.

EDIT3: I've got a zip uploaded, but without the pictures.

EDIT4:




http://img843.imageshack.us/img843/6442/measurementsetup.jpg
http://img651.imageshack.us/img651/5986/photoofbothtweeters.jpg

Hello, I have an urge to play around the miniature 6N16B and I want to use it as DAC output stage. Ive came accross two schematics that I like.
One is classic SRPP, the second is CCDA or constant current draw amplifier. You have two almost the same stages dc coupled together and one of these stages is anode gain stage, the other cathode follower. The idea behind this is that when signal is at the input, one tube will conduct equally more as the other one will conduct less - so the current draw from the power supply will be (more) constant. I have a question will this work in the reality like this and will it be better than using one SRPP stage?
My powersupply will be solid state, with choke input, and with electrolytic capacitors (maybe I will split it with some resistors or more chokes to high quality final filtration oil capacitor).
Do you really think 6N6P, E88CC, E80CC... are better than 6N16B? I have these tubes at hand.
Cheers, Michal

Hello.
I had this drivers awaiting a new Project but... I can let them go because I have too much things and just a few time for projects.

2x Dynaudio Esotar T330D in perfect working condition but with cosmetics scratches and dents
The front plate has scratches in one unit that has a damage in the rear chamber (repaired with sealant rubber).
In perfect working condition.








2x Dynaudio Esotec 15w75 15W-7504 4 Ohm.
LIKE NEW



I'd like to get 500€ for the pair and I prefer to sell together, but could split if there is interest for 15w75
PP fees and shipping not included

These speakers are well reviewed (Infinity Primus P363 Floorstanding Loudspeaker Review — Reviews and News from Audioholics), so I decided to buy them on a whim to see what all the fuss was about. Product specs at Primus 363 - Infinity

Well, they're not half bad. They're actually listenable and one of the few speakers I've owned that pairs well with my NAD C720BEE integrated.

Positives:

• They do the midrange very respectably, if a tad forward
• Likewise, the treble is clear as a bell, with the faintest touch of sibilance
• Decent mid bass, for their size

Not-so-Positives:

• A bit flabby bass
• I think they could benefit from some cabinet bracing
• May benefit from some judicious cabinet lining
• All caps in the crossover are electrolytic

In short, .. I think there are definitely some improvements that these speakers could benefit from. Some are obvious to me, and I'd like your feedback on others that may not be that obvious. As it stands, these are a great value, but I'm sure they can be improved somewhat, without busting the bank.

I hope I’m asking this in the correct area. I took apart the back panel of my NAD M3 in order to do a recap on it. The RCA jacks are isolated from the back panel using these small plastic pieces, white for the left channels and red for the right. The left channel is completely fine, but I guess the red dye in the right channel has lead to their destruction, they literally crumble when you touch them.




Here are a couple of the most complete I have, I know it’s a long shot, but does anyone know where I might be able to find these or a near replacement? I may see if I can find someone who can 3D print them.



Thank you,
Dan

-- SOLD --
(2) TAD TL-1601a Low Frequency Loudspeakers available
New in original sealed/taped boxes
$850ea
Shipping negotiable world-wide

Greetings to all,



I have developed a board for a heater supply that is capable of 1.5A and can be upgraded to higher currents by substituting a different part for the LM337



Its a mix of known circuits, and works pretty well in testing, there are currently half a dozen of these modules operating, and the first feedback is positive. With some raving reviews from some friends that have tried these in their amplifiers.



See the attached circuit diagram, its essentially a TL431 reference, biased by a LM337 in the negative lead, followed by a current source that is voltage driven by a comparator through a low pass filter.



The diode D4 increases the voltage over the current source by another 650mV or so, so the 2SC6144 transistor is in its linear operating region.



Diode D3 serves to keep the current ramp up characteristics of the current source independent of supply voltage, this means the circuit will have a nice soft start characteristic whereby the current is brought up slowly, keeping thermal shock of the filaments to a minimum. Furthermore it also provides a limit to the amount of current that a cold filament can draw during start-up.

R1 and R2 are the current sense resistors, with a 1n4148 for D3 the maximum drive to the opamp-transistor current source is about 650-700mV depending on exact supply voltage and diode production lot. This will yield a short circuit current of ~2A for the current source with the values as per the schematic.





Current source frequency compensation

R4 C1 serve to make the circuit more stable with light inductive loads, i have not optimized the value of C1 very much because the circuit seems stable with leads in of several meters.
Upgrade to 2.5A

By replacing R1 and R2 with 390mOhm 2W metal oxide resistors and replacing the LM337 with the 3A LT1033 allows for 2.5A of current.



Circuit advantages,


One of the advantages of the LM337 pre-regulator setup is that the voltage over the 2SC6144 transistor is tightly controlled by the circuit which increases reliability, and furthermore the input voltage is not too critical because the LM337/LT1033 both have internal over-temperature protections.



The diode clamping on the output of the comparator yields very nice startup behaviour on most directly heated tubes.



Noise is also very low, i cannot measure it very well with the limited test equipment i have available for the job, but most meters agree its somewhat lower than 100uV. With some popcorn noise visible on my Rigol oscilloscope.


Disadvantages



This circuit is not exactly efficient, by deleting the pre-regulator and lowering the value of the sense resistors, dropout could be lowered to half a volt. enabling the supply to run from AC to DC in most 5V and up DHT's



try the circuit yourself,



I have lots of boards available, and can also provide kits with all the components needed to build this circuit yourself.



There is a group buy for these regulators here: Group buy filament regulator for DHT tubes

Sound Diffusers 101: Free Designs for DIY Diffuser Panels

Based on the Honours thesis of Tim Perry of the University of Victoria:

http://arqen.com/wp-content/docs/Acoustic-Diffuser-Optimization-Arqen.pdf

dave

Good evening,

I was hoping someone could tell me why Q41 would be missing it's base voltage? See attachment. If I short emitter/collector, the PS and it's rails work as expected. I thought it might be standby pulling the base down to ground, but I bypassed that and the ~5V still does not appear. Thanks!

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