Hi all,

I have developed new digital crossover filters with the objective of getting the highest possible slopes under perceptual constraints (like pre-ringing)
A more detailed description is available here
I am looking for more ears to get additional feedback on these filters, so if you are interested you can contact me (you need to be able to implement FIR filters as crossovers)

Thanks,
Thierry

The mission is simple:
A friend of mine wants a car sub that could be also used on an a occasional outdoor event every now and then. He can fit up to 210L box in his car so I guess an efficient PA woofer would be ideal since he could get lots of SPL on like 300W amp (while using it as a car sub, for outdoor use he would probably use a different amp)
So far Beyma 18LEX1600Nd seems like a great woofer that can go really loud and quite low.
My questions are:
Is this a good idea?
Is that woofer okay or is there something that would work better for this use?

Have you ever compared your original recordings on CD with "remaster" versions?

Most of them are ruined using compression/limiting the signal! (reducing the dynamic range)

Here is one example :

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Now the remaster :

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They are literally killing our beloved music! (Alan Parsons , Led Zeppelin, Roger Waters , GONG ... just to name a few)

It's like your are listening to the music being using an overdrive!

Quieter parts are lost and be now in the foreground!

Louder parts are now overloud!

The original balance of the music is lost ... what a tragedy!


Uh - little mistake in the headline I wanted to write THREAT but one character went to digital dust ...

Hey all...
My current project has a controller board with three voltage regulators, two LT1963's and one LT3015 negative regulator. The "problem" which isn't a real problem is that both 1963 positive regulators are not completely shutting down when the shutdown pin is low. I get about 275 mV @ 170 uA instead of the 0 volts and "less than one microamp" it is supposed to show. Now I know that nothing will run on voltage that low but it seems weird that it doesn't go to zero volts like the LT3015 does. Is that just a quirk of the LT1963?

Here's that part of the PCB:

Any thoughts?

Mike

It was the beginning od 2012. I was still leaving in Japan and in the process of building the F5X Amp. EUVL designed a matched Pre-Amp and I started to collect parts for it. This time I decided not to go for the full F5X Pre assembly, as designed by EUVL, but to integrate various things.
10 years passed, the unit is not 100% completed, front panels still need to be designed and milled, but it's fully functional. Here are the highlights:
1) Two chassis design (PSU and Audio sections)
2) Dual mono
3) Fully balanced
4) DCB1 input buffer
5) Muses 72323 volume control
6) F5X Pre gain stage
7) CLC Psu with common mode inductors
8) Plugs to power monoblocks and control them via relays
9) Controlled with Arduino (Display, Endoder and Remote)

Everything that could be matched in this unit is matched.

It was a long journey, but I am very satisfied with the results. I learned a loads of things in the meantime. I developed a new library for the 72323 (72320 libraries are not compatible)
Things to do:
1) Front panels. The front panel where the display is located should completely enclose and shield the microprocessor.
2) Galvanic isolators between Arduino and Muses chips.
3) Listen
4) Listen
5) Listen

Greetings

If anyone has any of the following Transistors would be grateful to know.

2SB889
2SD1200
2SA950
2SA949
2SC2229
2Sk89
2SK163

Thank you for your time and consideration.

John

looking for any information on consort ca-4000 amplifier i purchased several years ago
there is very little information on the web apart from they were sold by laskys around 1978
any help would be appreciated

Hi all, recently completed another fullrange build and now looking for some advice on how to get the most out of them. I have Fostex FE208E sigma in the factory cabinet with FT17H tweeters crossed at 10k (i think?) and have a bit of budget left to treat them to a decent amplifer. So far I have run them from a basic Marantz AV receiver and a Musical Paradise 6W EL34 tube amp. I was going to go for a Muzishare KT88 amp that can switch between UL and Triode but to my ears the speakers sound better out of the Marantz than the Tubes up to now and the added power seems excessive given the high sensitivity. I have read before than some Fostex drivers are intended for use with higher output impedance but I'm now totally confused with damping factors, amp classes and different ohm ratings on binding posts. The potential is clearly there, spooky imaging and vocals + bass that can shake the floor, just not easy to pick an amp blind. TLDR: has anyone used these or similar drivers and have any advice on what might suit them?
Pics also show them with 208NS but thanks to a kind forum member I was re-united with the proper sigmas 😁

Hey all, I’m hoping you can help me out by answering a couple of questions for me. Comparing these two set, and I guess comparing other TO3P like NJW21193G/NJW21194G. I know the 21193/94 have a much slower Ft.

Would the 0302/0281 pair work in most instances where the 1302/3281 pair is called for? Spec wise they look to be identical other than the 0302/0281 pair being rated for 150w dissipation vs the 200w of the 1302/3281 pair. And then the 21193/21194 pair have that same 200w rating, but also rated for higher voltage and higher current.

I’m guessing for instance when building this STK-0050 replacement board that was wonderfully designed by great members here and audiokarma
https://audiokarma.org/forums/index.php?threads/stk-0050-replacement-for-sx-780-and-others.721181/
That the 0302/0281 outputs would work just fine in place of the 1302/3281. Are there many designs out there where the extra 50 watts of dissipation would absolutely be necessary?

And then comes the SOA of the devices, I’m guessing that the 1302/3281 is better in this regard, is that correct?

Here is why I’m asking. Parts are starting to get harder to source. The 1302/3281 packages are out of stock and have been out of stock. I still have a couple dozen of each though. I was going to buy in quantity.

Do I buy the 1302/3281 at $3.80 each and wait for them to come into stock which looks like it will be at least 9-10 months?

Or do I buy the 0302/0281 at a much lower cost of $1.50 each, but I have to buy in much larger bulk, minimum of 166 pieces of each device? Plus I get them now.

If there are many instances known where the 0302/0281 devices won’t work where the 1302/3281 do, then maybe it doesn’t make sense to buy so many and just wait until parts are back in stock over at Mouser/Digikey. But, if they will work in most instances (example being the STK-0050 board replacement I linked above) then maybe I should grab them while I can.

Dan

Hi
I'm building a 3 way speaker using morel components:
Tweeter: TSCT1044
Mid:TSCM634
Woofer: TiCW1258Ft

The speaker is divided to two boxes. one for the mid and tweeter and one for the woofer.

I started by building test box and advanced from there.
I saw a problem with the test box of the mid but i thought it was in issue with the internal of the box. but it looks like I was wrong.
After building the final box i saw the same problem.
The problem is a notch in the midrange measurements. -5db @ 2.1khz.

Ok so then I was thinking it is something with the edges of the box.
0.5 of the baffle width wave length is very close the 2khz.
I tried some kind of improvisation to increase the baffle width but it did not have any effect on this dip.

I was able to fix it in the XO but it is a constrain that i wish to get rid of.
I wish to understand the problem and may be to avoid it in the next design.

See attached files.
Thanks
Ran

Hi all,
In humble need for recomendation here 🙂

Room setup (see image):

• ~6x6m basement (2.25m hight) with projector
• 2*4m screen, give or take.
• soft materials (so far, - can be upgraded): acoustic curtains (marked in green) on both sides, carpet in the middle, sofa in the back

However, I do not have sound system, and want to build a set of speakers (marked S1+S2).
So far I am thinking I would settle for a stereo solid state amp (would probably buy used one from older times) and a pair of speakers.

I have done 4 sets of speakers by now (all were full-range, would love to try something new now), so it can be of (slightly) harder design/setup to increase the challange 🙂))

The only requirements:

• not bigger than 40cm in depth
• not wider than 80cm
• can be as high as needed (can be floor standing, can be on "legs") - as long as it fits in the room (2.25m is limit)
• a pair should not exceed 1500usd (max 2000usd) in price
• what they will play: anything on TV/Netflix/Apple TV.

would be so thankful for any type of advice 😉

I often see the modified second-order crossover topology, as I call it myself, used in many speakers. Notice the R1; it is usually found on low-pass filters in both 2- and 3-way systems.

The simulation showed that the R1 is used to modify the slope of the low-pass filter, or someone could define it, in other words, as a Q adjuster.

According to observations, its value usually stays in a range of 0.5 to 2 Ohms. I believe the manufacturers don't put it there randomly. Despite my research into many of Loudspeaker's cookbooks, I found little to no mention of them.

Therefore, I'd like to ask directly: Is there a formula or calculation method for R1?

Hi Guys,

I was wondering if you could share your experience and/or opinions regarding I/V conversion of a current DAC (TDA1541, AD1865 etc) with a transformer like Sowter 1465 or 1495 or similar good quality transformers. Such transformers are quite expensive and I'd like to make an informed decision based on your experience.

My current setup is a TDA1541 DAC in NOS mode with a passive I/V resistor of 50ohm. This feeds the grid of the Aikido preamp with 6N2P as first stage followed by 6N1P as second stage. Quite a bit of gain but I like the 6N2P sound.

Overall I'm very pleased with the sound however I do suffer of FOMO and I'd like to try a transformer coupled with a resistor. This will cost about US $400 for 2 of them which is expensive.

I'm planning to add a secondary TDA1541 in parallel. A single TDA has a 4mA p-p. Twin will be 8mA p-p. Based on sowter calculation, using the 1465 transformer and 8.2kohm on the secondary winding will generate 2V rms. This should be enough to skip the Aikido altogether.

Based on your experience, it it worth the money to go this route? Did it have an improvement on your current out DAC going from passive I/V resistor only to transformer + resistor? I'm not currently entertaining an active I/V conversion. I'd like to keep the signal path as simple as possible.

Thanks

Wow now would this be good for a field coil driver ? https://arxiv.org/abs/2307.12008?fb...iiZvB-2nIoHHOk89KcFv6fM_VV9tMeoLZzcdW0zjzZubs

The literature usually just states that emitter followers have a voltage gain of 1 -- but I would like to know how to compute that with a bit better accuracy.

With a 1 kHz sine wave, on point A I measure 4.36 Vp-p, and 4.04 Vp-p on point B, so the voltage gain is 0,9266.

The current through the driver (Q1) is 920uA, and the DC bias is right on target at +5VDC.

I tried to simulate the whole circuit in Multisim, and it's giving me identical Vp-p values for A and B, and that is most certainly not correct.

Hello there, I'm the author of a freeware package called PSUD2, a simple application for designing linear power supplies.

It's been around since 1998 and has been received a fair amount of use from the DIY audio and ham radio community, amongst others. I'm planning a PSUD3 which will have a new file format and allow some enhancements to be made, some of which I've had to hold back on due to the fixed file format.

Here's some of the ideas that are brewing the lab right now:

• Integrated diode modeling tool - add points from the data sheet to get the correct parameters
• Rectifiers as separate files rather than a single rectifier.txt so you don't get a wipeout every time the software is updated
• Diode parameters stored in the PSU file, makes things easier to share
• Chart preferences (line colour, width, style) stored in the PSU file so you can have a consistent look that works for you
• R type block before load (current limit)
• Stepped resistance load in addition to stepped current source
• Support for mercury rectifiers

Anything else?

Regards / 73,
Duncan

I've been using ALTEC A7's in my 600 s.f. workshop for years and am very happy with them. I have an additional set of 416-8 woofers, 811B horns and 802-8D drivers. I would like to build some enclosures/crossovers and use them in a 9x12 dedicated listening room but I'm thinking the 811B horns may not be the best option.

Would these B&C horns be more appropriate for this small room?

https://www.parts-express.com/B-C-ME45-1-Exponential-Horn-90x40-2-Bolt-294-622?quantity=1

One would think that with around 8 million people that there would be a parts store in Los Angeles! With the coming end of All Electronics there is no where to get any parts and hardware at all in the city. You can get wire and assorted hardware out at Apex Surplus but there isn’t anyone carrying high end caps and resistors in stock. Let alone tubes themselves! Does anyone know of a secret location to get parts without ordering from Canada or similar? I would think a US based store would do well. I’m almost tempted to get some investors and open a place!

I am currently doing an internship. Where I was given a side project in which I am required to create a sawtooth wave using a DAC Tester board that utilizes the AK4495. Initially, I need to establish communication between the DAC and microcontroller and generate a sawtooth. I have figured out how to read and write to the registers of the DAC. I need help generating the sawtooth through the i2s protocol.

Hi I hope you are all well..

Maybe someone could help me with an issue I have with this amplifier. I bought this privately last year. When i checked over the amp at home, one of the screen resistors had blown, I subsequently replaced this 2w 100ohm and fitted new valves and biased them. I also replaced the PS caps.

All has been fine for a few months, however last night the sound distorted then the amp blew its fuse. There was a bad smell of burning, upon inspection V4 and V6 had blown screen resistors and the output transformer on the right hand channel doesn't smell good.

I have basic knowledge in electronics, can use a meter. It could be a scrapper if the OPT is toast but any help welcome.

Anyone here had to fix those infernal paint peels on the edge of old Mac faceplates?

I've got one in front of me and can verify Testor's gloss black in the little bottle is real close but doesn't quite exactly match. Is there a known good paint for this? Please share what you've heard and thank you very much.

I'm sure that many are aware of early Fender amps being constructed of pine wood with finger joints.
I'm wondering when did Fender move to MDF for the boxes?
I'm looking at a used Twin Reverb empty cabinet and while it is old, probably 1960s the seller doesn't
think it is pine.
The grill comes off and is held on with velcro if that offers any dating info.

Howdy,

The project meant for these is not going to happen as I had hoped. For sale are two (2) FA253 plate amplifiers along with the remote kit and remote control.
I would like to get $1,200 shipped (after fees if required). The plate amps have never been used.


https://www.madisoundspeakerstore.com/speaker-amps/hypex-fusionamp-fa253-250w-250w-100w/
https://www.madisoundspeakerstore.com/speaker-amps/hypex-fusion-remote-kit/
https://www.madisoundspeakerstore.com/hypex-amplifiers/hypex-remote-control/

Hello everyone,

I wanted to 3D print a horn for my iPhone. Mostly just for fun but it should actually work.
I can handle hornresp but obviously i don't have ts parameters, so it's back to the roots (what I can't to).

What can we do with that? How long and big should the horn be and what could we expect in terms of performance.
Is it even possible to do something remotely useful?
LMK what you think.

Measuring the speaker, we probably have an horn throat of 11x3mm

Those are 2 measurements: The upper one is close to the speaker (1cm), the lower one is further away (10cm)

Hi,
I need to replace transistors on some amplifiers. The transistors are the combo Motorola BD139-16 / BD140-16 and the Motorola BD441 / BD 442.

For now, I found the combo Toshiba TTA004B / TTC004B and/or the Toshiba TTA008B / TTC015B to replace those. Is it a good replacements choice or do you have other transistors to recommended.
Thanks

Hi All!
My friend is working on an upgrade to hid Ultrapath based on this link. I just wonder anyone has tried it.
Section 6:



https://www.dmitrynizh.com/Ultrapath.htm#a_solution
The attachment is the circuit of his Ultrapath

Here is a creative way to generate a low-power, isolated auxiliary supply "for free": it uses the stray field from a conventional, 50/60Hz transformer.
If you can't beat it, use it !
The collecting device is simply a coil having an open magnetic circuit.
In this case, I have recycled a coil from a proximity sensor or a card-reader, I do not remember exactly.


When pushed against the laminations of a transformer, it has an inductance of ~1 Henry.

To improve the collection efficiency, it is made to resonate at the third harmonic with a parallel capacitor of 1µF, and the voltage is rectified through a voltage quadrupler:



The resulting voltage is sufficient to bias a zener, light a white LED and provide the supply of a LCD DPM (an ordinary one, requiring 1~2mA, not a micro-power):



The positioning of the coil on the transformer is quite critical:



Here, it is placed at the junction of the I's and the E's, where the magnetic leaks are maximal.

I made no optimization effort, and the transformer is of good quality: it is made by Siemens.

The scheme could be used to generate a bias voltage, or to feed a millivoltmeter, as in this example. The fact that the generated voltage is completely floating makes it particularly useful: it could spare a small auxiliary transformer

Hello all,

I am looking for a schematic or any other information you may have on this preamp. I wish to return it to original condition.

Thanks!

Hey Guys, A while back I bought a pair of used speakers that had Morel supreme carbon scw 636 mid bass drivers (the ones with the aluminum voice coil formers) . One of the drivers was bad so when I looked into replacing it I got a deal on a new pair so I bought both. After I installed them I heard a buzzing at certain frequencies in one of the drivers. when I inspected it they seemed not to be glued properly in one small section. I contacted Morel they sent me a replacement but did not want the driver back.

So I have one good driver and one driver that needs to be re-reglued. I thought I would pop in here before discarding these if someone could re-glue the surround to the cone they could have them for shipping cost.

Thanks! Dwayne (Halifax, Nova Scotia, Canada)

So we have:

300va toroidal with 2x 25v secondary

Soft start board with momentarily switch support

HTPC case, solid aluminium

Dual mono TPA3255 boards - fully balanced. XLR input only.

For context I also have a Musical Fidelity X200r and a Technics A900s. Both well regarded Class A amps costing 2 or 3 times what it cost me to build this.

It blows the Musical Fidelity out of the water, no contest. It's slightly better than the Technics, with a more relaxed sound and better separation.

I was dubious about Class D. Not any more.

Hi
I have an opprtunity to buy this:

https://www.dba.dk/andet-15-jbl-signature/id-1103395958/

I was thinking of putting it in my twin reverb, sort of making a "Vibrosonic" amp, because i heard one once, and liked the jbl 15" vibe.

I am very unvertain about the wattage this speaker can handle. Some say only 25, others say 60 watts.

Does anyone know, how much it can handle?

Btw. Will pull two tubes from the twin reverb, so there will be an impedance match, and less wattage thean 100 😉

Would like a pair of One Electron UBT-2 output transformers (4.8k:4-8-16 ohms. )

Terence

I have had a good search but can't find anything.
Does anyone have a circuit for the type 1 Cviller power supply boards that they can let me have a copy please?

Need help understanding dirty signals.
Pic below shows input signal vs output signal.
Where my brain loses the plot is when one starts to see dirty lines.
Is it a scope thing. It would be nice if there was a database or list explaining what this noise is. How its caused. And the different kinds of noise on signals.
In this input vs output the noise on the in (Yellow line) seems random. But I have encountered other types of noise where the wave form is made up of very clean clear small zigzag lines. Then there are those where the wave carries minor spikes inside the curve. Those I found seem to appear when there are dirty of failing caps in the circuit. Sorry if this is a very basic question. But it would seem I need to grasp these concepts to make any progress with this hobby.

Hi all, I am just wondering if 2 smaller transformers (separate transformer for each channel) will have any benefits compared to a single bigger transformer.

The reason I am asking this is because I am getting an old 2nd hand krell fpb 300cx (would need to recap it as well). The amp is a single 1700va transformer. Photos I googled seems to show that output was spliced to supply power to both channel.

I am just thinking if each channel gets its own transformer instead of sharing from a single one, would that be better?

have 2 of the Ghent RTX unbalanced to balanced input buffers for icepower or other
I have one Ghent audio custom case left (Mono) w speaker bin posts, XLR, RCA Power receptacle.

Hello everyone, I am seeking this communities knowledgeable advice. I am wondering if it is worth trying to find an amp that will power a jl audio 15w1-8 subwoofer.
link to specs:
https://www.manualslib.com/manual/490247/Jl-Audio-15w1-4.html
(Edit: The images are in post #5)

I have two of the jl subwoofers with one currently in a box. Both subs are old and have not been used for 15 years plus. I had purchased them for a car back when I was in high school.
Box cubic feet appears to be 1.71, which is below the recommended size for the woofer.

I tried hooking up the one subwoofer that is currently in a box and was disappointed with the results. I bought fosi amp linked below based on the amazon reviews but it seems it does not have enough power at 8 ohms to drive the subwoofer. At full volume on the amplifier and with boost of 4 db using voicemeter banana on my pc it still seems underpowered. It is better with the 4db boost but seems lacking as the volume goes up on my old loudspeakers.

Fosi Audio M03 200 Watt TPA3255 Subwoofer Amplifier Mini Mono Channel Audio Power Amp for Home Theater Full-Frequency and SUB Bass Switchable with 32V/5A Power Supply​

https://www.amazon.ca/dp/B07VHG2LR9?psc=1&ref=ppx_yo2ov_dt_b_product_details
I plan to return this to amp to amazon.

Use:
I would like to use the sub mainly for music but I would be open to building a better box for the second in my living room for movies.
Music: 80 and 90s dance music, some classic rock

However, I know my wife will not appreciate a 15inch sub in the living room. She is a fan of bose and their size of the speakers.........She thinks that they are too much and is happy with google home. I am currently borrowing a bose lifestyle 35 system from my father. I previously had a lifestyle 28 that failed.

I plan to put the one sub in a 14x16 room. It will be paired with two 3-way loud speakers with 12 inch drivers (midrange is only original speaker in the box). I currently power them with a rotel-1312 that never goes past half volume. Link to amplifier https://www.hifiengine.com/manual_library/rotel/ra-1312.shtml.

Looking for:
I am looking for a lower priced amp to add to this setup if you think the subwoofer is worth investing in. I have tried looking for subwoofers on kijiji but have not found any well rated sub for under 500 as I am looking for Canadian options. If I am to get another amp I would like it to have speaker inputs as the rotel doesnt have anything to output to the sub.
I would like to avoid using my computer and just use chromecast audio to stream music, or an old cell phone loaded with music, or streamed from plex.
I have the equipment to build another box if needed but it would obviously add to the overall cost. I also have a 3d printer if required and can do basic modelling.
I did take a look at winisd but I am still trying to understand it.


Any and all help is appreciated. Thank you.

A rather odd & interesting album related to AI & VR >

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I've recently come across Beyma's 6NFMW and just did input it's specs to calculate box and port size.

Fs: 40Hz
Qts: 0.34
Vas: 11L
*Port Length: 18mm (Working with this just to match the standard thickness of MDF/Plywood)

The program came up with a 14.5mm port size.
What I wanted to know is if this will cause any resonance or muddiness as the air travels out. I've yet to see a bass reflex speaker with a port so small so I am questioning whether it's something that shouldn't be done.

I am looking at Benchmark AHB2.

https://benchmarkmedia.com/products/benchmark-ahb2-power-amplifier

Regarding input impedance, it says:

50 k Ohms, normal mode
1 M Ohm, common mode

If I were to use a single ended passive "preamp" which number should I be looking at?

If I were to use a balanced passive "preamp" which number should I be looking at?

Thanks for reading.

KEF Loudspeaker Systems Guide September 1990

KEF Loudspeaker Systems Guide September 1990

KEF Driver Data Sheets

KEF Driver Data Sheets

Someone may find this information useful.

Hello. I have been reading up on using horns and waveguides with tweeters, and a few times I've heard mention of developing a passive crossover to "rotate" the frequency response to account for the rolloff in the high frequencies you get with horns. The higher frequencies will gradually and consistently taper off at the top end, so a passive network is devised that somehow rotates the entire frequency response such that the response is flat, instead of tapering downward as frequency increases. I don't see many people talking about this, or how to do it. Is there anyone who can point me in the direction of where to start? I am still working on developing an understanding of the effects of placing different components in different parts of the crossover, but I can't find any resources that explore this in depth. Thank you 🙂

My dad asked me to take a look at a little Rotel receiver that he has. It is a RX-1052. I have the service manual for it and was able to use it to replace a surface mount resistor that had torched. There was also an electrolytic in the same circuit that needed replaced. I’ve gone through in spot, checked several of the capacitors, and some of them have somewhat high ESR and some of them are OK. I have not checked any of the capacitors on the amplifier board as it’s mounted to the heat sink and I wanna wait until I pull it out. I am able to get output from the amp now, which I wasn’t able to before, but on the bottom of the waveform on both channels, there is this small clip. It doesn’t happen every time on the bottom. Seems like maybe every other time the wave goes down it happens.



Apologies for the blurry pic. I’m going to pull the amplifier board and heat sink and then go through and check the capacitors on the board, especially the ones close to hot resistors. I am also going to go through and check some of the transistors like the drivers and just make sure they are OK. Since I am seeing output, I am nearly certain they are just fine, but with the anomaly in both channels, I’m guessing it might be power supply related??? As I turn the volume up the clip gets bigger.

Thought I would ask here to see if the collective great minds might be able to give me some suggestions on what to look at.

Thank you,
Dan

I am restoring a TD124 Mk1 and I've ran into a problem where the the step pulley and idler wheel do not align.

With only 1 fibre washer and the nylon washer fitted on the idler shaft, the idler is about 1-2mm too high on the step pulley.



I have the idler rod which goes down to the cam mechanism as low as it will go, photo shows it in speed set to the '78' position (apologies if I have the terminology wrong)



Does anyone have information on the gap distance between the chassis base and the step pulley as I believe I could adjust the step pulley bearing housing slightly by loosening the nut and using a flat blade screwdriver to adjust the housing? Also, oil is leaking out of the bottom of the step pulley bearing housing - is there a way to stop that?

Anyway, I can't see how I can get any more adjustment on the idler as I think* I have it in the lowest position it will go. All the articles I find online take about raising the idler wheel position by adding more fibre washers (up to 3) but that's obviously not much use to me!

Any pearls of wisdom gratefully received.

Finally, here's a picture of how the belt is riding on the pulley in case someone sees something wrong there.

What difference between BY255 and BY399 diodes

What do you folks think of this idea?

I am thinking about using this slot loaded open baffle bass concept in conjunction with a ribbon ob using a BG RD-50 for mids from 350Hz to 4000Hz, then a Magnepan 60" ribbon tweeter for the highs. I am thinking that 6 pairs of the 8" GRS woofer would give me a slot array roughly the same length as the mid ribbon- the 8" would give a 350Hz upper limit which is perfect for the RD-50. I would mount the wings on the back of the baffle to isolate the mid and tweeter ribbons from the bass backwave.

The idea springs from the XSD Speaker thread here: https://www.diyaudio.com/community/posts/7414759/

Thanks!

Hello, i would like to present my headphone amplifier/preamplifier project. Lets start with the name, it was diverted from my real name, and thus the name "Zig-Zag" was born. The idea was to make great sounding, low noise headphone amplifier, with lowest possible distortion. The basic idea of designing an amplification stage is opamp with diamond buffer. Input signal comes thru film capacitor, which doesnt allow dc offset of the input device, to be amplified. Later on, the low pass filter, filters out all the high frequency mess. The input signal goes to the non inverting input of the opamp. In my case i choosed the LME49710HA, tin can version. Negative feedback is composed of two resistor, wich change the gain and also the compensation cap was added, in case of opamp oscillation. Blocking capacitors were added to the power rails of opamp for best stability. The operational amplifier will amplify the voltage and diamond buffer, composed of LED current sources and BD139/BD140 transistors works as an current amplifier. To protect the headphones from dc offset in case of some problems, protection circuit was added, it also works as delayed load connection, which removes the pop when amplifier is being turned on. Time of relay switch is set to 5 seconds. Power supply comes from Walt Jungs designs. It is composed of an opamp, wich works as an error amp. Two resistors connected to the inverting input sets the output voltage. Led diodes connected to the non inverting input works as a voltage reference. Opamp compares the two voltages and difference is being amplified at the output, wich opens the power transistor. Such a power supply is considered low noise with low output impedance. All the components are high quality ones, like ONSEMI/FAIRCHILD transistors, WIMA film capacitors, NICHICON and PANASONIC LOW ESR electrolytic capacitors, gold plated IC sockets, NEUTRIK/REAN connectors, Talema PCB transformer and ALPS potentiometer. Case is custom made from aluminium and steel, with custom engravings on front and rear panels.

Amplifier was tested with headphones like KOSS PortaPro, SONY MDR-7506, Beyerdynamic DT 770 and more. On the input, i tested dacs like Topping D10S, SMSL SU-1. Sound was very dynamic, without any noise or hearable distortion.

Device can be used also as a preamplifier, output jack for headphones works as an manual switch, when headphones are plugged in, the rear output connectors are disconected, when you unplug headphones, rear output connectors connects a thus it can be used as preamp.

Full specs:
Dimensions: 130x45x235mm
Output power: 1,9W 33R, 118mW 670R
Quiescent current of diamond buffer: 14mA (diamond buffer works in class A with all loads)
DC offset: about 0,3mV per chanel
Output impedance: 5R
Gain: 4.2x/12,5

I was contacted by Xyzkum that he had a "friend" ('Keith M.') who had an OPT transformer I was seeking.

'Keith M.' sent me several photos of the part from highlandox@aol.com, along with details.

I sent payment to his "wife's account" - 'Deborah Barclay'.

No response after that. I missed or ignored the signs, having transacted on audio sites and never having been ripped off until now. Buyer beware and learn from my mistakes.

What diode could replace 1ss106 (a) ?
Would bat 42 / 43 work , or are there better subs?

I recently posted a WTB here and soon after received a message from a DIYA member saying they had exactly what I was looking for and that I should email them at an aol address they gave in their message.

I checked the user account to find it was less than 1 day old and when googled the email address is reported elsewhere as a known scammer.

I reported the message for moderation and looks like the moderators have kicked the account as it does not come up now when searching member accounts.

Be careful and do a quick little due diligence if being approached in this forum.

Regards

Clayton

Hello, has anyone used TOROIDY 10K/4Ohms transformers for the ESL audio input?
Thanks

Hey guys,

I hope you are all well. First post here so if there's anything wrong with it, please let me know.

I have a CP70B that just recapped and replace all x9 original transistors with 2SK170. Though this bring the sound back to life, now I can hear a clipping sound specially when playing the lower octaves or when there are several notes played with sustain. I also changed the tantalum C110-111. The value of these two (470nf) seems to be crucial in how much signal passes to the next stage. I also tried with regular caps but not real audible difference and the problem was still there. I tested the trannies prior to replacing them with the DCA55 tester with no issues. Any ideas please?

Cheers,

Fer.

I bought 4 of these original LME49990 opamps from the seller on DIYAudio. I wanted to solder them onto adapters for my CNC Phono stage but got out of vinyl hobby altogether. I paid $80 for them and $10 for adapters. I will accept $75 for them shipped in cont. USA with Friends and Family PayPal payment.

I have perfect Audiogon and eBay rating so feel free to ask me for the feedback links.

Suppose a dome midrange driver has a natural roll-off frequency of 540 Hz with a 12 dB/octave slope rate.

Can we establish a higher-order slope by adding a passive (or active) crossover of the same corner frequency and same slope, i.e., 540 Hz @ 12 dB/octave, to this driver?

Will we obtain a new slope for this driver at 540 Hz with 24 dB per octave?

What's the simplest way to add reliable biasing to this OP stage?
(The VDC will probably be double, ~36-40V)

Hello!
I am ready to try something else in place of my pair of corner placed 18" subs.

I am thinking about evenly distributed, wall-of-subs, shallow sealed boxes.
In other words, on the front wall behind speakers. A lot of 18" sealed subs, wall to wall and floor to ceiling. Perhaps, evenly spaced, covering most of the front wall.

Maybe the "Bag End" style sealed subs and infra processing, but that's going into details...

"The wall of subs"
Is this a good idea for DIY project? It seems not too complex. Just a bunch of 18" sealed shallow subs + dsp + hefty amps.
Does this work for good quality bass and even bass room coverage? Acoustically speaking, any drawbacks here?
Are there articles on this topology / analysis?
How will it sound?

thanks!!

Mick's house gone in fire storm.

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Details and cct in November issue.
10+10W, 6L6, 12AX7
Looks way easy to build.
Interesting to see what a kit costs.

Edit - can't spell "Silicon" ^^

US speaker parts & electronic supplier Parts-Express.com is having a 20% off sale ending 8/5/23 EDT. Use discount code hotsummer$
What I needed urgently was a $13 replacement soldering iron to replace the one I tripped over. Electric bicycle is limited to 8 mph assist because I broke a hall effect sensor wire.
What bonus I ordered was a pair of Eminence Compression Drivers N314X-8 for a savings of $46 each. I've been slobbering over these for 2 years; I have had the 15" woofers that long and the plywood almost as long. Plenty of woofers, mid range, crossover parts etc. available. Annoying I couldn't calculate the crossover values at 2 AM.

All Prices Include Shipping, with-in the USA, and PayPal fees!
People outside of the USA message me about shipping and we can try and work something out.
All Prices Include shipping, with in the USA, and PayPal fees!
Heavily modified Fostex TH-900 Lawton Mark 4 Museum Quality African Rose wood:
These headphones have been heavily modified. I replaced the drivers with the MK2 TH-900 Drivers, the new drivers have about 10 hours on them. They have also be modded by @John Massaria 1 on top of the Lawton full upgrade. The wood is a lot darker than the pictures show not sure why it is so light in the photos. There are also a couple of cosmetic marks on the metal around the cups. The cups themselves are in fantastic shape. They also come with a hard case. I also found a pair of Yaxi Pads that I’m going to throw in with the headphones: $1000
More Photos: Fostex TH-900 - Album on Imgur

Philphone TH900 Drivers With custom painted grills and Baffles:
The excellent TH900 Driver Philphone. Custom made my a Reddit user in small batches. Mine are the latest version with the balanced output upgrade and custom painted grills and driver baffles. The grills are Orange and the Baffles are Blue. They come with the stock pads, ZMF Ori Perforated leather pads, Stock pads, and Dekoni Replacement pads(forgot to take pictures of the other pads buit they are included). Like new condition: $800
More Photos: PhilPhone - Album on Imgur 1

Kennerton Rognir Dynamic JM MK1:
Bought these in the middle of January, 2022, directly from Kennerton. So they still have 2 years left on the warranty They are in excellent condition. I’ve probably put about 20 hours in-total on them. After I got them I sent them to @John Massaria 1 to have him mod them. After getting them back they have a much darker background with tighter control in the low end. The mod improved almost every aspect of the headphones. they are quite similar to the HD800s in tone but with a little more bass. They are in the Baltic Sea color. They come with the stock 1/4 cable, stock ECL-03 pads, pleather carrying case, and cloth pouch: $1200
More Photos: Rognir Dynamic - Album on Imgur

Kennerton Gjallarhorn GH40:
Got these at the same time I got the Rognir Dynamic, January, 2022. So these also have 2 years left on there warranty. They are in excellent condition. I’ve maybe put 5 hours on these headphones. They are made out of maple wood. I found these headphone to be the most comfortable of the Kennerton line. They are the light Maple color. They come with the stock 1/4" cable, pleather carrying case, and cloth pouch: $600
More Photos: Gjallarhorn GH40 - Album on Imgur

LSA HP-Diamond:
Bought these new from UnderWood in March, 2022. In excellent condition. I believe they are B-stock due to the color of the wood going from light to dark. I really love the look of the multi color wood cups. I’ve put about 40 hours on them. they come with a $350 upgrade cable made out of litz copper, gold, and silver. The current pads installed on them are the ELC-02 pads. They come with an extra set of ECL-01 pads which make them much more neutral sounding overall. They also come with a Pleather carrying case and the stock 1/4" cable: $1800
More Photos: LSA HP-Diamond - Album on Imgur

LSA HP-1:
I am the second owner of the headphones. They have about 100 hours on them. They are in great shape. The only flaw I can see is there is a small mark on the headband, see more photos. The current pads installed are the ECL-01 pads. They come with an extra pair of ECL-02 pads which improve add more bass and low end extension. They also come with an extra silver plated cable. Come with the stock 1/4" cable and a pleather carrying case: $1100
More Photos: LSA HP-1 - Album on Imgur

Audio-GD NFB-1.38:
I bought this new from Audio-GD, fully upgraded, back in 2019. The original cost with shipping was $950. It has served me well for the last 3 years. It is a fantastic sounding DAC and very hard to beat for the money. The only reason I’m selling it is because I went to an R2R DAC a few months back. It is in very good condition besides a scratch on the bottom of the unit. It is quite large and weight a fair bit. So be sure you have space for it before you buy it: $750
More Photos: NFB-1.38 - Album on Imgur

Heart Audio Cable Collection:
Bought these new from Heart Audio in July, 2022. I haven’t actually used any of the cables. So they are all brand new. Included in the collection is a 6’ HC-7(Dual mono 2.5mm), 6’ HC-9(Dual Balanced 3.5mm), and HC-10(Dual mini-4pin XLR): $50 per cable
More Pictures: Heart Audio Collection - Album on Imgur

Pi2aes Black Plesxi:
I’m the second owner. It is in excellent condition and works great. Fully built. Includes a power cord and micro usb. It is great little device just. I just didn’t really have any use for it. It comes factory rest so you can set it up how you want: $325
More pictures: Pi2aes - Album on Imgur 1

Hello,

Long story short: I need to extract a negative rail from a 275-0-275Vrms transformer winding. As the transformer is a Hammond, we can assume the voltage will be a bit higher in reality. The negative rail will be used for some Mosfet followers direct coupled to a quad of 6S4S (soviet 6B4G) so a sudden loss of voltage due to diode failure would be distastrous.
Would one 1N4007 or UF4007 per "phase" be enough or should I put two in series?
My choices are pretty much limited to: 1N4007, UF4007, 1N5408 (all 1000V PIV) or C3D02060F (600V PIV SIC Schottky).

Hi, I'm looking to upgrade my current subwoofers that I use for outdoor live sound, also some playback. All the music is usually classic rock or metal, so not looking for any extreme low frequency. I have 4 JBL 2279H drivers laying around and want to get the best output from them that I can for my situation.

My tops are 2 JBL SRX835P, sub amp is a lab gruppen clone FP20000q, and a peavey vsx26e is doing the processing.

The specs for these drivers I want to use are below:


To me these drivers don't look like the best choice for a tapped horn, but they are something that I already have on hand, so currently i'm thinking either build two double 18 BR cabs (These drivers are used in the SRX828) or maybe build four keystone subs? I'm open to other suggestions using this driver, I'd like to keep the woodworking on the simple side if possible.

I took in a White Audio Labs B3 amplifier to repair from a local audiophile. The left channel wasn't biasing up but the right channel seemed to be working fine. The customer had already replaced the 220uF feedback down e-cap on the left channel driver board due to low capacitance, but the other parts that I tested checked okay. I pulled the ZTX transistors that had obviously been running quite hot and discolored the pcb. Those ZTX parts checked good with the tester. The amp circuit is pretty simple so I pulled the driver board and drew up schematics in Kicad. They're attached.

I ended up finding some dodgy solder joints on the rather fragile driver board from the left channel. After touching these bad solder joints up the channel started biasing up. The DC offset in the right channel was < 10mV and in the L channel its about 65mV so they're both okay. I ran it for about an hour on the bench and then put it on the AP analyzer and immediately noticed a difference in gain between channels. I ran a freq response and that graph is attached. The left channel is the bad one. Upon doing some more probing in the amp I discovered that several of the K1058's and J162 laterals are running hugely different bias currents. The highest are measuring about 25mV across the 0.100ohm source resistors, the lowest are measuring around 9 - 10mV across the 0.100 resistors. So each channel has a couple of much higher current lateral devices in the mix, so its not just one channel with this issue. This is a large difference in idle power dissipation, with the 60+VDC rails this is about 15W for the highest measuring outputs and 6w for the lowest. This level of imbalance seems to me to indicate that the outputs have been compromised at some point. I cannot see where the output mosfets would've had this level of spread between the Vgs voltages when the amp was built. I told the customer that a full set of replacement select grade Exicon's may be in order.

I do worry that oscillation may have been a problem with this amplifier in the past and may be even more of a problem if I install the Exicon's. So extra compensation will likely be needed. The right channel in this amp has an extra capacitor strapped in parallel across the C2 capacitor shown in my driver pcb schematic, it was tacked onto the backside of the board. It seems to me that this would've likely been placed there when the amp was built to tame some oscillations seen when it was built. The left channel doesn't have this extra cap added.

Thoughts or ideas?

I have it connected as 3,5k now but want to connected as 5k.
I have been searching on the web but cant find any info.

Hi all,

I inherited a pair of DM603 speakers, but the tweeters are in bad condition and so are the passive bass radiators. Does anyone know of some suitable aftermarket tweeters and woofers that would fit in these speakers? As it would be a shame to throw these speakers away.

Hello. I'm trying to repair a Spectro Acoustics 500sr amp . It appears to have 4 blown output transistors. Is there a suitable replacement for the Motorola 150-0068 ?
Does anyone know where I can find a schematic for it. HI-Fi engine shows one available for download but they're not taking any new registrations,so I'm unable to get it. TIA.

Hi guys,

Anyone having information about high voltage JFET's ..probably which can support voltages of magnitude 150V [VDS]

thanks in advance...
K a n w a r

Can someone please help with a good resolution schematic of the old Sansui 5500 receiver (not the newer AU-5500) , as the one I got is sadly in a very poor PDF quality.....
Thanks in advance 🙂

3 Executone PA amps available, 2 with matching date codes and power transformers, one a few months older with a slightly smaller power transformer. Same output transformer on all three. One original cover/cage will be included with the older unit. Untested, no tubes. No obvious damage except for the usual dirt and corrosion. I believe these were working when removed from a factory facility about 25 year ago, have been in storage since. No tubes, but each unit has one preamp tube shield that I neglected to include in the pictures.

Asking $60 each, $110 for the matched pair, or $150 for all three. Shipping at buyers expense at 20lbs per unit from 11542. (I would pack two in a box at 40lbs and use a second box for the third to keep the weight manageable.) More pics available on request.

I'm not very active here on diyAudio, but I'm JonL on AudioKarma and enginejon2003 on eBay if you want to check me out.


Note the difference in PT size.

Some years ago I bought a bunch of unknown transformers at an estate sale. (Cool detail - it was the estate of a physics Nobel laureate!) The transformers had no documentation other than part numbers on the boxes and units themselves. Schumacher has no record of these and web searches come up empty. I measured the voltage ratios as shown in one of the attached photos. There's one filament transformer, two pairs of P-P outputs (four total OPTs, but two different part numbers and voltage ratios), and three different individual P-P outputs, all different from each other. A total of eight units. I'm looking for $100 for the lot plus shipping (15 lbs) from 11542.

I'm not very active here, but I'm JonL on AudioKarma and enginejon2003 on eBay if you'd like to check me out.

More pics on request.

HI. I have this lm4500 decoder and wish to install it in my troughline stereo.

Would anybody have any images and or clear diagrams for its connection. The ones i have are not very clear and i dont want to do any guess work with it to mess things up.

I have some capacitors and resistors. It would also be good to hear which parts you recommend for connection.

I enclose an image of the decoder.

I have completed my build of the Elekit TU-8200 and am having an issue with the left channel. No sound and the left channel tubes are significantly cooler than the right. I did modify the build slightly by replacing the standard volume POT with a TKD 2CP-601 POT and by replacing the 8200 transformers with LL2777B transformers (the 8200VK option).

The schematic for the 8200 is here:

Initially, the left channel would work fine for 5 to 10 minutes and then drop out. I did some basic research and troubleshooting (swapping tubes around, checking cables and connections…) and made an assumption that the Q1 transistor, part of the active automatic bias circuit, was bad and replaced it with another A1266 transistor. Since this replacement I have had no sound on the left channel after powering the amp. I have done some basic troubleshooting since then, visual, continuity, hot spots and I am not seeing anything obvious to my limited experience. I’m at a loss and am concerned that my limited troubleshooting ability has made things worse.

Below are my readings at the test points listed in the schematic:


Any guidance and advice is greatly welcomed.

FYI I have cross posted this in r/AskElectronics.

Bill

Pass F5t Fe Boards (UK)

Hello!
Looking to purchase a Sencore PM 82.
Email cesaudiopro@yahoo.com

I was very excited when i picked these up, i have always wanted a pair!







They look awesome and belonged to one owner, who 3 years ago had them reconed (lockwood). They are made in 1979 and in mint condition.

So i was expecting to hear some beautiful breathtaking sounds coming from these, but instead they sounded dull and laid back, almost muffled, the bass was lacking. They just didn't hit the sweet spot i was expecting great things, my kef 105.2's and Ruark talismen II sound and perform much better.

I tried different amplifiers from my quad ii, pass alpeh m, B&W mpa1 etc but still they didn't sound right. Even my wife said they don't sound right, before she moaned at me about bringing bigger speakers home which don't fit 🙂.

I thought perhaps the crossovers being almost 40 years old could do with some TLC, i know that these components can drift in value. I thought maybe they need room to breathe and need a big space?

If i put the volume up they start to sound better, but then it's just too loud to enjoy. Low listening levels are not a strong point with the speakers, they are just missing something.

Anyway i thought i'd take them apart replace the x overs.





Heavy speaker to take out i can tell you!

old crossovers look like new?! Not sure if these are original components or they have been replaced? Could these be the problem in how my speakers sound?

which of these transports will give me the least trouble and sound the best?

I want to start modding, but my skills are at 0 and I have a hakko iron in my shopping cart, but not bought yet.

I want to replace the lytics and do a tube clock mod on either machine, also, which would be easier to work on?

Hi I haven't used your forum before, but have read several posts. I hope this is a good place to ask this. I want to horizontally bi-amp a class AB amp (for highs) and class D amp (for lows). I understand that both amps must have matching gain and input sensitivity. The AB amp has a fixed 20db 3.2v input and the D amp has 28.6db 1.43v input. The class D has a variable gain so I can match the 20db, is there a way of working out what the input sensitivity will change to when lowering the gain down to 20db. If it makes a difference both amps are balanced and into a load of 8ohms, the AB is 130 watts per channel into 8ohms and the D is 185 watts per channel into 8ohms.

Please don't get to technical with me lol I'm more a dabbler than a technician.

Many Thanks

I have been using a diy LM317/337 power supply +15/-15vdc supply rails to power a DIY preamp for a few years.

I have noticed, just, that the positive regulator (LM317) is notably hotter than the negative. Both have the same heatsinks/conditions etc.

Is there a reason for this mystery?

One CViller power supply for sale. Suitable for all First Watt diy amps.

£20 with UK delivery.

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The driver PDFs ...

https://www.arylic.com/pages/download

I wonder about zero reaction of the DIY crowd - anything wrong with these offers?

https://www.arylic.com/products/midbass-speakers

https://www.arylic.com/products/air-motion-transformer

Who knows what's going on here?