Looking for a AN8290S spindle motor drive IC for a Technics CD player.

Hey people,

I found these "LM1875T" ( I assume the common, not so bad sounding, fakes as everywhere). I just forgot I have them, as I changed to LM3886 just because of the higher output power. I remember them as really good sounding chips, and it would be a pity to not put them to use.
I thought, maybe I could try two of them for my tweeters, which are powered by LM3886's atm. It's all fully active, so the different output power can be aligned easily.

best regards

I'm gauging interest, here.

I built an integrated amplifier with B1 as preamp, but I didn't like the amplifier section. So I tore it apart and sold the amplifier section. Now I'm debating what I should do with my assembled B1 with Korg Triode.

If I hold on to, it might sit for a while. It's only been for a couple of months and it's already covered in dust; sorry for the pics. So selling it might make sense. Let me know if you are interested.

This board is the OG. It's the Christmas board. It's been fitted with high end parts (Vishay Dale resistors and Nichicon audio capacitors) and spec'd out to handle up to 35V.

I want to build a sub for the LFE channel for movies. I have good main speakers but I'm lacking rumble. After much digging around, I was able to find drivers with decent Q and low Fs in the local market (Argentina). The rest of the available drivers in the market are "car audio" drivers for SPL competitions with Fs all >40Hz.

The available drivers are Alpine 12" with the following specs


I've simulated them in WinISD and got these curves:




Running environment:

• The speakers will run in a 3x6 meter room where one of the corners is a bathroom, so the room is more L-shaped (I can provide a floorplan).
• I ordered a UMIK-1 so I'll run REW here to characterize the room as soon as I get it
• There will be DSP and EQ applied after characterization with REW.

The conclusions I arrived to were the following:

• Vented box will be required for low freq (of course)
• Series S will be the cheapest but requires a large box
• Series R will perform the same as an S in a much smaller box
• Series X will go much lower, in a box the same size as S

Now, the questions:

• What's the required SPL for "feeling" LFE channel? If I'm watching a movie and I want to feel the explosion on my chest, how many decibels is that?
• Do I want such a big-and-deep driver as the Series X which will go low , but will require a considerable box? Or will I get enough with a Series R that requires a fair bit smaller box and delivers very respectable -3dB of 21Hz in a 67L box?
• I suppose the answers to the second question is actuall the first: if the required SPL is enough for a R-series with more power I'm willing to sacrifice efficiency for space. I guess it's fine to run the driver at 100W instead of the larger and more expensive one at 50W to compensate, if the required SPL dB is reached?

BONUS: closed box option

All 3 drivers in closed boxes will give a -3dB of 45Hz with pretty much the same curve. 20Hz will be at -16dB in all cases. I read about using room gain to take advantage of subwoofer rolloff. I'm all for using a small box but, is room gain predictable or reliable? Is it a curve or is it spikey depending on what's in the room and its layout, etc? I don't think it'll be very helpful if the room only gives me gains on a single frequency but the rest is the same.

I imagine it's always possible to tame down the excess bass with DSP, than trying to recreate it with DSP gain?

Hello all! I just completed a pair of speakers with a set of Dayton RS-270-8s Tang Band W4-1337s, and a Vifa ring radiator mounted on a horn. I'm crossing them over using a Dayton DSP-408.

They sound pretty fantastic tonally-wise. Problem is, I'm powering them with 3 mono TPA3116d2 no-name boards from eBay and a 24v 16 amp power supply. They are extremely hissy (it's not the Dayton, I've removed it from the chain). Even after lowering the gain as much as possible, hiss is still there, probably exacerbated by the tweeter horn. Hiss can be clearly heard from the listening position. Also, power on pops are so strong they'll eventually damage the woofers.

I'm looking to replace the amps, but I've seen that most class-D amps prefer 4 Ohm loads and my woofers are 8 Ohm.

I've tried narrowing down boards, but all I can find are no-name units from eBay. I can't know if they will have hiss or pops.

I've been looking everywhere and I see that power output will be greatly diminished because of my 8 Ohm woofers.

My search has narrowed down to perhaps the TPA3250 or the TPA3251 chips. I've found some boards on eBay, but I don't know how good they are. I also know I'll need to change the power supply to a 32-36V one.

Any recommendations for a good board will be welcome. I'd love to stay with the 3116 chips, but I can't find any quality boards out there... all I've seen is this one but I don't know how good it may be.
https://www.amazon.com/TPA3116D2-Ta...12-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&psc=1

Here I will detail some of the construction details and set up of the Pete Millett Korg Nu tube Balanced preamp that I have built. Schematic is reproduced for convenience.

Jfets- I chose to use the Toshiba 2SK170BL for Q1 thru Q4. However, I did not have 16 matched ones, so I used the lower Idss values for the followers Q1A thru Q4A and the higher ones for the CCS Q1B thru Q4B with small degenerating resistors typically around 5r to get 0VDC offset. My Jfets were mostly in the 7-9ma range. I asked Pete “Could you please explain to me why you have chosen 1k source degeneration resistors (R6/R8, etc) in the Jfet followers as opposed to self biasing them without any?” His reply “Adding a resistor helps to stabilize the stage current without requiring selecting FETs for a particular current (they can vary a lot, maybe 2:1, without it). If the FETs are matched, the resistor on the upper FET also will give an output voltage equal to the input voltage, as the voltage drop on the two resistors will match.”

Capacitors C6, C7 and C13, C14- I wanted to use film caps from the get go but they are large so I asked whether smaller value caps could be used. Pete responded “The coupling caps are big largely to avoid bias shifts with the signal. Since the tube is in A2 and draws some grid current, using a lower cap will increase distortion because at low frequency the cap will discharge more on positive peaks than negative. So I wouldn't recommend going any lower.” I chose Clarity Cap CSA 12uf for the caps before the Nutube and CDE 940C caps for the ones after the tube. I mounted them under the PCB, as shown in the attached pic.

Microphony- The Nutube was mounted on top of a piece of foam mounting tape attached to the PCB. Additionally, each PCB and cap assembly was mounted using 40mm standoffs onto a base plate which in turn was attached to the chassis bottom plate with foam tape. The PSU’s and the transformers and stepped attenuator were also attached similarly. I cannot hear any pinging when turning the volume knob but you can clearly see it on display as spikes around 5khz when doing the THD plots if you tap on the case. I used the Salas DCSTB Psu’s at 15v output. Nice!

Set up – It took me a very long time, mostly due to inexperience, to get the plate voltage settings where they sounded best to me. I used my Focusrite 2i2 in balanced mode and ARTA software for the FFT plotting and set up. I finally decided on a setting where I could null both H2 and H3. From these null points, R12 was turned ACW to increase plate voltage to get H3 just a bit off its null and R13 was turned CW to decrease the plate voltage of its respective tube section to get H2 up where I want it. This gave the sound I was looking for with the resultant THD plots shown. The plots were done at 0.42V output after 2 hours warm-up using 332k plate resistors.. Here are the plate voltage readings:

L channel TP3 4.07V TP5 6.85V
R channel TP3 4.14V TP5 6.76V

Measured gain was 12.89db Left channel and 12.73db Right channel.

The above settings also result in “negative phase H2” as defined by Nelson Pass. The XLR output connector is normally connected to the PCB outputs i.e. PCB output+ and output_ are connected to XLR pins 2 and 3 respectively. To verify negative phase H2, I temporarily reversed output XLR 2 and 3 and easily noticed the sound had shifted forward. I much prefer negative phase H2.

Sound- I use this preamp to feed my Sony Vfet power amps and Troel Gravesen OBL 15 speakers. Compared to my BA3 and DCG3 balanced preamps the difference I find most striking is that each musical note sounds fuller yet is extremely clear. The other two preamps also sound clear but seem thin in comparison. If you increase H2 further the sound becomes more euphonic but gets muddier. It sounds better to my ears with a very low H3 and a much higher H2 than with a somewhat higher H3 and lower H2. Mention must be made that the overall setting is tuned to perform best with the Sony VFET amps. All three of my preamps throw a very large soundstage but the Nutube preamp sounds the most realistic, especially with classical. Late night listening at lower volumes is also very satisfying. To my great surprise even large scale orchestral works sound excellent.

Thanks to Pete Millett for a well designed, easy to assemble PCB. I like it that all the lettering on the PCB is outside the part outlines so that they are not obscured once the parts are stuffed. Thanks to Nelson Pass for his very informative articles on H2 and to Salas for the excellent DCSTB Psu’s and his ever willingness to answer any and all questions.

Hi!

I was wondering if there is a schematic out there for an audio peak indicator circuit that uses 1 multicolor (red/green) led that turns green under 0dbu, orange betwern 0dbu and +10dbu, and red above +10dbu. The trick here is to be able to turn off the green led gradually after 0dbu and completely off after +10dbu.

Any ideas? 🙂
Thanks!

I put some stuff on sale on Swap Meet, but forgot to say anything about these. So I guess it was meant to be that, following Codyt's example, I'll give these to someone here on the Pass Labs forum. This forum has been a huge aid and inspiration on my Audiophile journey. Also the kindness and willingness to help even us "not so into the knowledge", is beautiful. So it is only fitting to give something back. So here is a chance to get MOSFETs for the F7 - or other amp.

I really don't know if there are many people seeking after ALFETs, but we will see then.

Giveaway:
ALF08P16V x2
ALF08N16V x2

So the basic rules are the same as with Codyt (I trust it's okay to copy your text Codty? You said I better then I could):

Rules and conditions:
One entry per person. I'll pay for the shipping. As long as the Finnish post will ship to your country/address. Ideally these would go to someone who hasn't had the good fortune of winning other lotteries – but if you'll use them, you may sign up.

How it'll work:
To enter, just copy the list of entrants, paste into a new comment, add your DIYA username to the bottom of that list and post. At about 11pm (local time) on the January first 2024 (1.1.2024), I'll make a comment saying that entries are closed. I'll take the final list of entrants, have my daughter state a random number between 1-100 and we'll see who's name the count stops on - that will be the winner. From there, that person simply needs to PM me their mailing address and I'll get them posted.

Happy and blessed New Year everyone!


EDIT 28.1.2024

This original lottery for a quad of ALFETs is over and out. But now, since then, Nelson has offered to donate 50 more quads.
To get on track with the current situation, jump to post #63 – and then to post #101.


EDIT 2.2.2024
The original and also the secondary lottery are completed.
If you are reading this after 1.2.2024, you were too late. Sorry for that.
But have a nice day!

Hi all diyers,

I have Alpair drivers in the pencil enclosure. I have no complaints. I would like more life out of it. I listen to a lot electric blues and old rock.

I found the https://www.speakerdesignworks.com/halcyon design, it seems very interesting as it adds two small woofers. So the enclosure is nice and small (9 inch face). Since I can control the WAF factor, would it be «better» to use one 12 inch driver of simiar value as the two SB Acoustics 6 inches ?

Does it impose more difficult blend for the sound of the two drivers ? Is it more difficult to make the crossover, it will be my first one.

Thanks for your advice,

Walter

I made a wall-mounted Speaker with CHP90.
I used 9mm MDF to reduce the weight as much as possible, but it is strong enough and I don't feel any vibration of the box.



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Hello Everyone,



I have stumbled upon an issue while doing an application. In this application there is an existing multimode fiber which is installed. We will be using Sony PXW-Z90 and QuestTel's optical extenders. My application exceeds a one kilometer distance which is not supported by multimode fiber. Since changing multimode to singlemode fiber is not an option, I would like to know if there is an option that exists that doesn't require me to change the existing infrastructure to boost the optical signal.


I am truly looking forward to a good response,
John

Hello diyAudio forum,
I was looking at the SE/SE Wire headphone amp recently but I found out that the LME49610/49600 buffer isn't in stock anymore so I looked at alternatives and found the BUF634A.
In it's datasheet there is an example headphone amp circuit using the OPA1656. I drew up a full schematic in Kicad of the circuit Login to view embedded media What are your thoughts on it? Should I change anyhting about the schematic before I go ahead and design a PCB for it so I can test it out? Also, would running it off of two buck boost converter modules to create a dual rail PSU be a good idea to power this? Kind of like how this person does it for his eurorack PSU.

I am looking for advice with crossover design. I am attempting to rebuild a set of Cerwin-Vega! L7 Bookshelf speakers. I have decided to use the following drivers:

Visaton SC5-8 Shielded 1/2" Polycarbonate Tweeter 8 Ohm.

Tang Band W5-2143 5" Paper Cone Full Range Driver 8 Ohm.

The enclosure volume is 0.44 cubic feet or 12.4 liters. I am reusing the existing port (1.69” x5" cut down to 3"). I am stuck with the 0.44 cubic feet as I don’t want to cut open the boxes.

I have been experimenting with Xsim for designing the crossover but have a couple concerns, mainly around the impedance curves. I am not sure what is going with the impedance curve for the Tang Band W5 driver, it has a massive spike at around 54 ohms. Nothing seems to smooth it out and I am wondering it this has any potential ramifications to harm my amp or the speaker itself.

Andy help would be greatly appreciated. I have attached a couple images from Xsim.

Hello all.

I am planning on using an unbalanced 1/4” TRS output to send stereo line level to a balanced stereo amp with XLR inputs.

The cable will be Canare L-4E6S. In the middle of the cable I’d like to use a small box to do the actual splitting (i.e. 1 in, 2 out). Should this box be non-conductive, or metallic? If the latter, to which ground/shield should I bond it?

Hello, I have sunfire tga-7401 amplifier. The amp has three fuces. Two for current sources and one for ac line fuse. Unfortunately one of the fuce holder is broken and I couldn't find the replacement. Without the fuse holder, fuse does not stay in. Any advice would be greatly appreciated. I have attached the pictures of fuse holder and amplifier.

The Data for a MC7805ABTG is "Linear Voltage Regulators 5V 1A Positive" Datasheet

The Data for a L7805CV is "Linear Voltage Regulators 5.0V 1.5A Positive" Datasheet

I'm not sure if the amps matter in a voltage regulator as long as its not less than.

Thanks

Hi,

With the help of ChatGPT I was trying to build the minimal JFET buffer.
The requirement for the buffer is to take high impedance preamp output and help to drive low impedance next stage.

So, ChatGPT has suggested the following circuit, claiming «the buffer will effectively isolate the preamp from the lower impedance load that follows».



I am not a real electrical engineer and the circuit kinda makes sense to me. I have tried to assemble it and I get completely no sound at the output. JFET doesn't seem to conduct any signal. I have tried it with J201 and with MPF102, no luck with both.

It is simple enough and I seem to have checked everything multiple times. And ChatGPT keeps insisting it should work and I am stupid.
Could somebody give me a hint? Is it a viable circuit? What is missing for it to work as intended?

Thanks.

New. Two pairs of short binding posts and corresponding red/black spacers. $188 retail. $145 including shipping in CONUS.

I'm in the planning phase of a 2 way MEH with the Celestion H1-9040 horn. I have the H1-9040 and it looks feasible to add either 1 or 2, 3-4 inch midrange drivers on the top or bottom of the horn.

This will be my second MEH so I'm familiar with Hornresp. What I'm not familiar with is the exponential horn. Horn flare at the beginning (1" CD driver opening) is slow to expand. This appears to allow the mid range opening at S2 to be less dependent on close location to the CD driver opening?

I only had a few hours to play with HR last night so I don't have any graphs to post.

Anyone else try messing with MEH plus exponential horn who can offer advice?

John

Hi all.
I´d like to get some help from you, if you could look at this.
A few years ago I bought this amp.
I replaced nearly all of the transistors+output transistors, diodes in power supply (except the 2 pieces of Zener diodes ), all the caps (except the one at MIC input),
many tantalum caps (except the TT and TUNER board).I cleaned all the switches and pots.
I measured resistance between grounding points and the chassis, everything seems OK.
I re-soldered everything again.
But still is some slight buzzing noise comming from the right channel (under the transformer), but the left channel is much better.
This buzz is there even when the volume pot is all the way down.
If I put some metal plate under the winding of the transformer, hum is gone but the buzz is still there.
I am sure, it is some bad grounding somewhere.
Idle current : 15 mV both channels
DC offset: R: 20mV. L: 2mV
The low noise level is still the same.
Could you help me please to find the reason?
Thank you very much.
Jan.

There has to be a way to get that 90 degrees on a stylus without the damn air pump!!


I don't want to go off track in other tonearm threads so I decided to start a new thread focusing on the discussion and design ideas for pivot style tonearms that can attain tangential tracking, a pivot linear tracker if you will. Sounds like an oxymoron but it can be done.

To be brief, most tangential tracking tonearms are typically air-bearing tonearms that allows the stylus glide across the radius in almost frictionless manner to simulate how a record is cut on a lathe. Other means of this gliding action can be also achieve via linear bearings like rollers on a rod or bushing on a rod, etc... Some concept arms even suggest using floating opposing magnets. The flaw of such tonearm is that the horizontal mass is enormous regardless of bearing quality, low friction or no friction. It limits the choices of stylus, depending on its compliance. And the use of an air pump is not for everyone to say the least - a personal pet peeve of mine. The genre of electronic servo detection pseudo-tangential trackers like the Rabco tracking across the record in tiny little arcs constantly self correcting its way to the end of the record is not part of this discussion here. Anyway, this thread is NOT about the above tonearms. We want to talk about pivot tonearms that can track tangentially by changing stylus angle simultaneously.

The best examples are actually currently available in production. By now, many people have heard of the Thales tonearm from Switzerland. It is a pivot style tonearm with an extra pivot at the headshell area right above the stylus. The changing angle is always 90 degree to the radius because it is part of a triangle that is inside a semi-circle that adheres to the Thales theorem, that is, "Thales discovered that the circumferential angle subtended by a triangle in a semicircle is always a right angle. As a result, the half circle above the hypotenuse of a right-angled triangle is called the Thales Circle."

http://www.tonarm.ch/kommentare/thaleskreis_e.html

6moons industryfeatures: Thales

.



.

With the basis of the Thales Circle, the designer Micha Huber devised a tonearm that can track any point inside the semi-circle always 90 degrees to the center of the record, voila a linear tracking tonearm that pivots without any linear motion. Genius! The tonearm appears to be executed with quality construction and precise worthy of a Swiss watch. So far it is the ONLY tonearm on the market that is capable of 100% geometric accuracy in maintaining tangency, at a price,of course, as it sells for, I believe, 6000 €.

.



.

Visually, it has the look of a Rube Goldberg device but looking closely, everything seems to have its specific function for good reason. I don't want to write a white paper on the Thales design but for those who are interested in examining it more closely, feel free to explore its website. But this tonearm does give a good example of the objective here.

.

Thales will introduce a new tonearm named "Simplicity" that looks simpler and elegant and even though it is not 100% accurate in geometry but it reduces the tracking error to a maximum of 0.008°! Pretty damn good in my book.

.



.

There are historical predecessors of such design and one can find that in the classic Garrard Zero 100.

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.

And the Burne-Jones arms.

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.

One can also find examples in contemporary designs like the RS Labs RS-A1 arm with a pivoting headshell.

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.

"Prototype of the 'Bajulaz' tonearm on a TD-124. It was designed by Ing. Bajulaz to overcome the geometry problems of the conventional tonearms, but allegedly it wasn't so good for the new stereo cartridges and therefore never went in production."

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.

I will continue to upload more pictures and present ideas to stimulate discussions and, hopefully, inspire the DIY spirit.


.

I have a few tubes for sale. Each pair sold separately, or discounted as a bulk sale.

2 tubes each below

GE vt-52 / 841. (pair $425)
Philips 814 (pair $325)
GM70 Russian Graphite Plate (pair $250)
Valvo Aa ($299)

Reasonable offers accepted.

All tubes are NOS. 5-day money back guarantee (less shipping).

Happy to provide photos upon request.

Thanks!
Pat
banpuku@mac.com

Does anyone have a copy of the software for the Circuit Ed CT100 ?

I have misplaced mine!

Hello.
Need help for connecting external DAC for AMC CDM7 / MD5401 cd player.
Original player no digital output.
When I need solder 2 wires on PCB board for coaxial output.
Thanks.

Schematic

https://elektrotanya.com/amc_cdm7_cd_player.pdf/download.html

Hello felllow audio DIY-ers!
I'm just starting to build a 25 year old project...a stereo push pull tube amplifier I "started" to build when I was in highschool...but never got to finish....I guess it's about time
Back then there was no chance to get a good output transformer...for me anyway..and the internet was not what it is today...some had dialup I didn't...so I gathered the chunkiest transformers I could find planning to open them up and rewind them, all local magazines with tube amplifier articles...found old electronic engineers in my town to source schematics datasheets and..the tubes of course. Things stopped when I tried to open up and rewind the output transformers ...good luck with that!..and highschool finished priorities changed...
I the meantime I occasionally "light up" about tube amps or other things while browsing the internet so at some point I purchased toroidal output transformers, all components for a linear regulator and an old grundig tv set transformer
So having basically all components sitting for the amplifier...I got this "urge" a few days ago to build it and I started putting together a chassis with all the components.
I don't know what's gotten into me I'm not even into tube amps anymore...or am I? I find myself salivating when I see nice tube amps or full boxes of interesting NOS tubes and wish to have them
I'll post some pictures and later I'll have some questions for sure...

Electronic Schema Power Amplifier LJM L20SE

Electronic schema and analysis

Schema: Amplif_L20SE.pdf - Google Drive

Project: Amplif_L20SE.ms14 - Google Drive

I am not marketing this product and I am not the author of the project. I did the schematic circuit for analyzing and sharing information.

Hi all, I have this 8-pin audio connector for my Alpine amplifier. The yellow power cable wiggled loose from its pin, and I have been unable to remove the pin from the connector, despite my best efforts filing paperclip ends into a flat profile to make a depinning tool.

How can I remove the pin, and where could I order new pins (or reuse this one) ? Thanks!

I am located in the UK. Thanks!

This is possibly self-answering, but I‘m looking for confirmation:

4PDT „ON-ON“ is the same as
4PDT „ON-NONE-ON“?

https://eu.mouser.com/ProductDetail/NKK-Switches/M2042SS4W01

https://eu.mouser.com/ProductDetail/NKK-Switches/M2042SS4W03

I‘m asking because I used something that looked liked a „4P3T“ (?) but it had continuity to an outer channel when it was in the center position. Removed it and want to avoid further glitches…

I have the parts together for a quick and dirty 2 way open baffle system. One of the uses I have for them would be as studio monitors and the desk has the center of the 12" bass driver basically at ear level. I would be using a DSP amp so I can mess with delay and other parameters.... but I was thinking about mounting the full range driver coaxially. I don't think I've seen such a setup here outside of pre-made coaxial drivers.... am I missing something?

First post to the forum...

I recently purchased a few of the LM1875 XY boards from Ali Express, but there was no schematic included to compare with the data sheets for the chips, and as a relative newbie to DIY Amplifiers and I am confused by a few items.

I was initially confused by J3, but after a few hrs of research online, I found some photos of a KBL04 bridge rectifier in its place. I was also confused by C1 and C4, as there were numerous holes supplied and it only called for a 1uf capacitor. I have since realized that the extra holes were to be able to choose different sized capacitors perhaps?

Anyway, after scouring some threads, it appears that there are some issues with the power supply being inadequate... So I was wondering if anyone has used these boards to build either a LM1875 or TD 2030/2050 "decent" sounding amplifier, if they wouldn't mind sharing their build ideas or links to threads that I can explore, or any other recommendations before I start soldering... I'm basically just looking to build a decent sounding power amp to power some YAMAHA S115V PA speakers that I had laying around....

Thanks in advance!

Hello i want to build a music subwoofer ( bass reflex ) with tight articulate bass with good instrument separation and reasonable extension ( 35 hz ) and i can choose 1 x sb acoustics woofer or for the same price 4 x peerless ( sort of like Tekton 4-10 SUB , they will be 2 x 2 driver modules but stacked onto eachother ) . Will the sba be bested by 4 x cheaper drivers ? Are any downsides to using multiple bass drivers with slightly different parameters than one driver ? Looking at dibirama THD measurements the peerless sub starts to distort heavily below 60 hz compared to even SB34NRX75-6 which is worse driver than NRXL-08. Are there any alternative drivers for cheap multiple drivers sub ?

I will be posting information about my new design balanced amplifier.
Today, the amplifier schematic, and a picture of the amplifier.

Soon, the power supply schematic, another picture, and my discussion of the design decisions I made.

Later, measurements of the amplifier performance.

https://rolfbader.de/the-metamaterial-wall


Has anyone built this? I'm hoping to start experimenting with some of the panels he describes

Hi,

Member from many years ago returning with some unused goodies to sell.

Took part in the 2003 group buy of the 11x11 R-Theta 65340 heatsinks and never quite got around to building the project. At this stage, it's better that someone else have some enjoyment from them.

If you can believe it, one of the boxes had been sealed since 2003. Here's a quick pic of one of heatsinks out of the packaging:

I'll sell them all for $240 Canadian plus shipping, on inflation alone they'd sell for $316 now. They are heavy and there are two (original) boxes to be shipped, so I expect the shipping quote to be sizeable.

I'm in Halifax, Nova Scotia, if there is anyone nearby interested. Can provide more pics if necessary.

Thanks for reading, and I hope there is someone out there that can turn these into a decent project.

Robt

I am looking for a good sounding power amp for an active system.

To drive a pair of 5" drivers per channel, 8ohm Celestion TF0510MR closed back, wired in parallel.
The drivers have no crossovers hi or lo pass, and operate with acoustic frequency limits / horn loaded through taps in a band pass, between around 325Hz to 954Hz.
What's below that and above that is killed off with EQ.

I've been using a little 5W EL84 SET amp and recently trying a Topping TP-60 (I know😀), just to try.
I wonder if the damping factor of the SET is too low for the drivers. It operates but...
The TP-60 seems to work okay but I want to up the game if possible, within a reasonable budget.

All help gratefully received.

I have a set of potted output transformers, purportedly from a Sansui amplifier/receiver. They were touted by the Ebay seller as transformers compatible with EL84/6BQ5 outputs, which would place them at 8K optimum plate-plate impedance. As I usually do, I scoped out the primary leads (~400 ohms plate-plate, with a tap at 200 ohms - smells like a P-P transformer). I drove the 2 plate leads with a sine source at 50VAC, 300Hz, and got 0.905V out. This has me scratching my hard, as this indicates a turns ratio of 55:1, and a bona-fide 8k transformer would have a turns ratio of 31.6:1, and an output of 1.6 V or so when driven with 50V P-P. The turns ratio indicates 24k load at primary side with 8 ohm load. What were these transformers intended to do? They look good for about 15W apiece from the standpoint of size. Higher voltage input? Lower output impedance.? I hunted around on the secondary taps, and 0.9V or so is the most I can get out of them with 50V plate-plate drive on the primary side. Both transformers measure the same - head-scratching time...

I'm looking to get into voice coil rewinding.
I have a few questions.

Where can I get some supplies?
Like a winder that can count turns?
Those metal cylinders of various sizes you use to build a new coil around? Not sure how to find these because I don't know what to call them.
Material to build the formers out of?
Is there anything I need to be aware of when buying magnet wire, other than gauge?

What do I use to hold the windings together? Epoxy? Varnish? Youtube videos showed epoxy. Slow cure?

I can replace voice coil assemblies and do reconing and refoaming already.

Hey guys, I'm inexperienced in the realm of tape decks, walkman, etc. I recently bought a Kenwood KX-50 tape deck. The tape deck turns on, however, it doesn't play anything. So I opened it up and a lot of the belts had melted. The ones which were still intact were very stretched... So I went onto ebay and bought a 'kit', only to later realise upon the arrival of the kit, that the kit only contained 2 belts - I needed all 5...
I see that HifiEngine has the service manual which - I hope - may contain the measurements for the belts. I figured that I could buy some cheap belts from AliExpress which are similar in size to the originals. I just can't find the measurements of the orignals, so my plan is being halted. HifiEngine's registerations seem to be closed as well which I find quite bizarre... I was wondering if there's a kind person out there which can help me get a hold of the measurements or service manual from HifiEngine or any other site which can provide either. I also tried ElectroTanya but to no avail... Thank you very much in advance!

I am selling my NAGRA IV-S professional reel to reel broadcast recorder. Offer includes the NAGRA IV-S plus ANT-2 power supply as well as a genuine Nagra leather carrying case/bag.

It is in excellent technical and cosmetic condition, a true collector's item.

Location: Budapest

Asking price: EUR 4.690 + shipping

I am happy to send more photos for serious buyers.

I am selling my Lyra Dorian, which has been checked and updated with a new boron cantilever and Micro Ridge stylus by Ana Mighty Sound. Since the retip it has been only used 10-20 hours.

Frequency range : 10Hz - 50kHz
Cantilever system : Boron rod cantilever, natural diamond, Namiki MicroRidge line-contact stylus (2.5 x 75 micrometers profile)
Channel separation : 30dB or better at 1kHz
Internal impedance : 9.5 ohms
Output voltage : 0.6mV (5.0cm/sec., zero to peak, 45 degrees)
Cartridge weight (without stylus cover) : 6.4g
Compliance : Approx. 12 x 10-6 cm/dyne at 100Hz
Centerline through mounting holes to stylus tip : 9.5 mm
Recommended tracking force : 1.8 - 2.0g
Recommended impedance : 100 ohms to 47 kohms

Tracking ability: 80 micron / 315 Hz / lateral / 18mN

Location: Budapest
Asking price: EUR 790 + shipping

I can pack it very safe, I shipped many cartridges in the past.

Condition: used, but with new silicone damper in excellent condition and low playback hours. Silicone damper has been installed by Ana Mighty Sound.

Specifications
Stylus: Shibata
Cantilever: Ruby
Colis: copper
Coil imp.: 6,5 Ohms/ch/DC
Tracking ability: 70 micron / 315 Hz / lateral / 21mN

(Tested in an IKEDA IT-407 tonearm with DIN 45549 test record.)

Location: Budapest
Asking price: EUR 1390 + shipping

Condition: used, in excellent condition and very low playback hours. New silicone damper has been installed by Ana Mighty Sound.

Tested in an IKEDA IT-407 tonearm with DIN 45549 test record.
Tracking ability: 120 micron / 315 Hz / lateral / 22mN.

Specifications:
Type : Moving coil
Output: 0.21 mV/cm/sec (RMS), 1.05 mV @ 5cm/sec recorded velocity
Stylus: Super fine line - F. Gyger II ( 6 x 40 micron ) nude diamond
Cantilever: Aluminium Tube
Tracking weight: 2.2 -2.5 (2.4 grams recommended)
Cartridge body: 5 axis machined solid aluminium alloy
Generator fixing: Unique 3- point rigid fixing, spiked to body (without adhesive)
Cartridge fixing : Standard 0.5 inch centres (12.7mm)
Recommended load: 30-1000Ω (100Ω recommended)
Coil impedance: 24Ω
Frequency response: 5Hz - 30kHz
Channel balance: Within 1dB
Channel separation: 0dB/ 1 kHz
F I M: < 0.5%, 19μ
Cartridge weight: 8.2 g

Location: Budapest
Asking price: EUR 1800 + shipping

Condition: used, but in very good technical and comsetic condition, with low usage hours.
It has been checked by Ana Mighty Sound.

Tested in SME V tonearm with DIN 45549 test record.
Tracking ability: 80 micron / 315 Hz / lateral / 25mN.


More information about the cartridge can be found here: http://ortofon.com/hifi/products/historical-products/mc-rohmann

Location: Budapest
Asking price: EUR 800 + shipping

Hi.
I have a uniherz jello star phone with bluetooth 5,3 and some noname bluetooth 5.3 in ears. I wonder if that means automatically that they both support lc3?
Also I wonder how its possible to see what codec is being used. I can't find this information on my old Redmi either.
Cheers!

I would like to share my latest blog where I test microphone distortion between four different mics.
https://josephcrowe.com/blogs/news/microphone-distortion-comparison

Hello friends,

Many years in ago, in 2006, I built this 6SN7 preamp. I sourced the schematic from the late Wim Bouwman (Mr Valve) in South Africa. I used the preamp with a solid state power amplifier, and it sounded really good. The gain was somewhat high though.

I have lost my notes on the project, and cannot seem to find satisfying info on a simple yet effective power supply design for this build.

Below is are pictures of the schematic.

Could any of you tube aficionados point me in the right direction? It would be much appreciated.

Thank you in advance,
Christian

I want to connect 5.1 audio to sony gn88d from my pc.But sony gn88d does not have 5.1 channel aux input.On its main board,There is an FPC connector named FR,FL,SL,SR,C,SW etc.

I connected phone audio there.Audio is not clear and broken audio. In schematics PCM1609KPTR (Digital to analog converter ic)> circuit ( filter or something)>M61530FP-D60G(surround volume control).



When I connect phone audio to the circuit(filter ?) before the surround volume controller ic, the audio is clear but 90% volume is decrease.

Any solution?

Or

Is it possible to convert the phone audio signal with the same characteristics analog audio coming from the PCM1609 ic?


Sorry my English is bad.

I recently did a test running one of my class D PA amps against my hifi (cambridge audio azure power amp). This was done through my hifi speakers (focal aria 926). PA amp drove the left speaker whilst the cambridge drove the right. When sat at a distance with not great room acoustics it sounded like the same amplifier driving both speakers. But putting your head right next to the drivers and moving going back and forth between the left and right speaker there was a noticeable difference. The cambridge amp just had greater high end detail and better separation of the midrange elements. Id say the difference was comparable to testing a 500 quid integrated hifi amp versus my a mid / higher end power amp.
It got me thinking that maybe for my PA system I could move away from the high power class D amps for the top end (dual diaphram coaxial compression drivers - 700hz up) and perhaps go with a much lower powered class AB amp instead. I believe these are inherrently much cleaner at the top end than class D. I'd need a 2 channel amp per driver / stack and ideally with the ability to set rms / peak limiters via DSP.
There was one unit I found which does seem to fit the bill, the QSC XTi 1002. Has all the attributes and isnt too expensive per unit, but the question is would I be wasting my time even obtaining and trying this amp. Will it actually have a cleaner top end more on par with my hifi power amp? Or should I just get saving and go with a higher end class D amp instead ( powersoft, mc2, linear research etc). Any thoughts appreciated.

Hi, I have a Home Theater PC that I use to feed my DAC from the USB. To get a better signal, I have a SoTM pci to USB card. For the streaming Imhave etither JRiver or Roon. My question is I know that a PC is a very noisy environnement. Does anyone know a way to at least replace the PSU and put a linear PSU for ATX. In my research, I have found the Teradak system but it’s way over priced. More then $2k just for a power supply. Or am I better go to a NUC pc and add a good linear psu. In this case I won’t be able to use my SoTM USB card…

thanks

I'm about to start making a pair of celestion TF1525e speaker boxes (https://celestion.com/wp-content/uploads/2019/10/188.pdf) and was wondering if anyone had attempted making these before and had any specific tips on making them, or if anyone had more general advice on speaker cab construction.

For the panels, I'm going to get them cut on a cnc machine to keep the edges nice and straight. I'm either going to use the recommended 15mm birch plywood, or an alternative to birch as its quite expensive at the moment. To secure the panels together I was thinking of using wood glue and countersunk screws to increase the grip between the panels (is this nesacery or will just standard brad nails work instead?). I'm going to leave the finish as exposed wood instead of painting so will need to apply some hard wearing varnish on them so that they don't get banged up as easily. I might look to make some stands for them as well as this is the recommend positioning for them (but I might also jsut use them on a table depends how lazy I'm feeling).

For making the crossover I'm going to use the plan shown on the link above, although one part of it has confused me a little. On the design C1 and C2 are shown next to each other but with a "/" in between. Does this mean that the values are interchangeable or will I need two capacitors for the low pass filter? Also on the diagram for C2 the value is in uH instead of uF, I'm guessing this is just a typo though and I'm just going to use a uF value instead. For the inductors I haven't really been able to find ones of the exact values so I may have to buy some larger ones and uncoil them to get the right value, does anyone have any experience of doing this and know how to get the best results? I've also drafted up a components list of what I'll need for the crossover:
LF:
L1: https://www.bluearan.co.uk/index.php?id=CNVACLD180 - potentially use a core from willys hifi -https://willys-hifi.com/
C1: https://willys-hifi.com/products/mkp-polypropylene-hifi-crossover-capacitor-10uf-250v
C2: https://willys-hifi.com/products/mkp-polypropylene-hifi-crossover-capacitor-2-2uf-250v
R1: https://uk.farnell.com/arcol/hs25-1r-j/resistor-wirewound-1ohm-5-axial/dp/2478173?st=1ohm resistor - more on https://willys-hifi.com/collections/resistors-20-watt

HF:
L2: https://www.bluearan.co.uk/index.php?id=CNVACMC072 - will need to uncoil to give desired value - potentially use a core from willys hifi -https://willys-hifi.com/
R2: 12 Ohm 20 Watt 5% Ceramic Wirewound Resistor - Willys-Hifi Ltd - more on https://willys-hifi.com/collections/resistors-20-watt
R3: Jantzen Superes 10W 100 Ohm 1% Crossover Resistor - Willys-Hifi Ltd - more on https://willys-hifi.com/collections/resistors-20-watt
C3: https://willys-hifi.com/collections...lypropylene-hifi-crossover-capacitor-1uf-250v
C4: https://willys-hifi.com/collections...propylene-hifi-crossover-capacitor-6-8uf-250v
P1: https://cpc.farnell.com/raychem-te-...-radial-1-35a/dp/FF02433?ost=1.35a+polyswitch

Please refer to the link at the top if the component acronyms don't make any sense.

I think this post covers my basic prebuild understanding of the design and how I will execute the build, if anyone has any tips to add or things that I should be considering which I haven't mentioned then please let me know. Otherwise just wait for more posts to show progress updates on the build!

Sanyo/B&O Icepower 200AC Rev.D, schematic about rev. engin., not complete finished

some time ago I had make trobleshooting and repair by a ICEPOWER module from B&O. Therefore I must create a schematic, that was not available by the manufacturer. But the schematic was difficult to reconstuct, because the PCB use multilayer technology. So any connections are not to see and some other are unknown, where do they go (at whole four or five wires - I think).

Nevertheless this schematic could be of interest for one or the other.

Perhaps one of the members this can complete.

hi,

does anyone have a schematic for a micromega duo cd3.1?
the power transformer has died and i need to know the rating/voltages so i can get some kind of replacement.

it started to hum, then over time developed a slight buzz until it started really vibrate almost like a mobile on silent, then it suddenly stopped and then i noticed the player was off. tried the fuse, cable and then i opened up the cd player and could see that the top of the transformer has gone a brown colour like it was giving off loads of heat

how does this kind of thing happen? am i right to think that with age and heat that it has somehow 'de-laminated' itself which caused it to vibrate? the micromega has a circuit which is always powered up unless you unplug it, mabey thats why it died?

i have searched the web and found what i think are suitable replacements but without knowing the specs im stuck.

any info would be much appreciated
thanks

Hello,

I'm trying to restart my micromega solo after a long period of storage. unfortunately it seems to me that the transformer is out of order. do you know the reference of this transformer and possibly a site where to buy this part?

thank you!

Edit June 5, 2020: Here is my completed FH9HVX in dual mono using a cast iron griddle heatsink:



More info on the Griddle Amp here.

There was a very nice little Class AB amplifier I worked on years ago based off of Apex Audio's wonderful little FX-8 lateral FET amp. Back then I did not want to use the lateral FETs because they were pricey. So I set off to make a hexFET based version. It was called the FH9, and it sounded very good. If one used generic resistors and caps, you could build the whole amp for under $10. The layout was done by several people, Sonal K and Prasi, but the one that caught on was the Sonal K layout.
Here was the Sonal K layout:


Many people have built this amp since then and it has been a favorite. At one point, I swapped out the transistors for some high voltage ones and hooked it up to a $20 Abletec +/52v SMPS. Running a pair of IRFP240/9240's I was able to eek 150w into 8ohms with it.


That's 34.5Vrms into fan cooled 8ohm load:


Over the years, I continually get requests for help with this amp or people asking for a PCB etc. I have noticed that lately with the Covid19 quarantine going on, many people are not having as much cash on hand for premium parts. So I thought it might be neat to revisit this amp and see if we can make a nice performing budget 100w amplifier. Naturally, I have enlisted the help of JPS64 to do the layout, and Vunce to help with the beta testing. Vunce has since gotten the original FH9 to work and is about to get stereo sound any minute now. In the meantime, I have put the circuit back on LTspice (it was on Tina in the early days). And I have tweaked it for 52v rails and nominal output up to 100w into 8ohms. No fancy parts and not even four MOSFETs. Just 1 pair per amp if you use Fairchild with a higher power rating, should be fine. No matching to do. The amp is super simple and very pleasant to build in one evening. If you happen to have an old Abletec 225w SMPS, dust it off and you can have one of these amps playing. It has a very powerful bass and nice overall presentation. One of my favorite simple amps to make and listen to. Many people can vouch for its sound if you check on the Apex thread.

On this amp, one can use nice Dale resistors, boutique input coupling caps, or you can use no name Aliexpress resistors - it won't matter. I just ask that you get either genuine Vishay IRFP240/9240 or genuine Fairchild FQA40N25/FQA36P15's (about $7/pair). You can run it at +/-35v of course as a 50w amp, but I suggest going for the +/-52v version and getting it to crank to 100w without a sweat. THD predicted at 100w is only 0.005% and at 25w is less than 0.003%. Dominant second/third order harmonic distortion, and a semi-monotonic descending higher orders (ok, so it's no SE Class A amp in profile...) But what it has is some great bass dynamics, and killer foot tapping immediacy. A very fun amp to listen to and play with. Cheap fun.

If you don't want to go with a cheap +/-52v SMPS, a single 300VA 38v trafo will work nicely or dual 200VA 38v trafos and a simple CRC PSU with four 10,000uF caps each will work fine.

Here is the LTspice schematic (in JPS64 part notation):


Here is the LTspice file for the simulation.

Here is the predicted distortion at 25w into 8ohms of 0.0027%:

Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+03 1.984e+01 1.000e+00 -0.72° 0.00°
2 2.000e+03 3.797e-04 1.913e-05 134.57° 135.29°
3 3.000e+03 2.438e-04 1.228e-05 -115.92° -115.21°
4 4.000e+03 1.048e-04 5.279e-06 173.49° 174.21°
5 5.000e+03 1.811e-04 9.124e-06 -110.61° -109.89°
6 6.000e+03 8.789e-05 4.429e-06 173.30° 174.02°
7 7.000e+03 9.443e-05 4.758e-06 -114.64° -113.92°
8 8.000e+03 7.359e-05 3.708e-06 172.29° 173.00°
9 9.000e+03 4.741e-05 2.389e-06 -123.30° -122.58°
10 1.000e+04 6.369e-05 3.209e-06 170.96° 171.68°
11 1.100e+04 1.842e-05 9.282e-07 -149.71° -148.99°
12 1.200e+04 5.589e-05 2.816e-06 169.47° 170.19°
13 1.300e+04 1.325e-05 6.676e-07 127.79° 128.50°
14 1.400e+04 4.934e-05 2.486e-06 167.92° 168.64°
15 1.500e+04 2.346e-05 1.182e-06 94.55° 95.26°
Total Harmonic Distortion: 0.002677%(0.008486%)

Click to expand...

FFT for 25w into 8ohms:


Here is a sneak preview at the 100mm x 100mm PCB that JPS64 is working on. We will have optional flying leads with quick connects for the MOSFETs.


The pre-proto FH9HVX built by Vunce is working very nicely. Here it is in an old donated chassis and powered by the Abletec SMPS. There is not much to this amp. But it packs a punch.



Here is the pre-proto FH9HVX all buttoned up:


Edit May 9, 2020: Vunce has made Mouser shopping carts for this project here. There is a basic version for $32 and the premium version for $56.
FH9HVX - Budget Conscious 100w Class AB for Lean Times

BOM in Excel format v01a here:

FH9HVX - Budget Conscious 100w Class AB for Lean Times

The prototype schematic is here:


Here is the All Cee's PSU that is recommended for use with the FH9HV:
FH9HVX - Budget Conscious 100w Class AB for Lean Times


Edit Aug 2, 2020: please be careful of the orientation of the LED in the input stage CCS. The Anode goes to ground - not cathode.

Hello to All !
This project started because I have a 7L small box and not to know what to do with it.
Looking for small driver which can fit in this and can make bass. The SLS P830945 seems to be a good candidate, It is a subwoofer and can handle a tweeter till 3KHz
For the tweeter, the Peerless DX20 was a good candidate but it is a 3/4", go to 2Khz could not be its cup of tea. SB acoustics have the sb26 in small form factor ! Good ! and don't know how this series works, I would like discover. The project was on the way ! Peerless has made a passive radiator, the SDS P830880 (Thanks to @wolf_teeth for the TS parameters, publish on Part-express forum). After some simulations of the box with this passive, it was OK.
Not a lot project with this tiny subwoofer SLS 5.25 only one, 3 ways, high end project, goes further in definition : Purveyor; a dynamite small 3-way with concussive tendencies....
After some hard work, measurements, simulations, found a good solution, a crossover ~2400Hz LR4 with good phase tracking. The sound is great and this speaker can play loud, and goes low ! For the price it is a bargain.
Pleased to shared this project. I think this 5.525 subwoofer can have a lot of application to make high quality system in HC, HIFI with two in MTM/MMTMM to make center and floor standing speaker. The sensitivity is low but not a problem with modern amplifier.
The speaker :

The name bulldog is coming from the Peerless 5.25 with it big roll surround. It remind me this dog. Can play loud in a small box.

The technical details :


The price : 160€ drivers, 100€ crossover parts, 100€ for a pretty box. Total 360€ (~400$) for a pair !

It was a pleasure to discover this small woofer. I have used the 10" and 12", they work well in open baffle design with low distortion.

Have fun !

Edit : I forgot to mention this option if the rear panel permits you can add a second passive P830880, it is cheap and +3dB in the bass (60Hz). The box resonance rises from 40 to 50Hz. The binding post should be small. I don't test this option but I suppose the level of bass becomes terrific, useful in large room.

By a friend occurs an issue at the display on this device:
Naim | All-in-one-Player | Uniti-Serie | SuperUniti

Obviously there are several other models with the same technology and the same basic deficiency.

You can find a lot about this on the web, but no helpful information:
Naim Audio Forum Archive
NaimUniti Mk.1 display panel fading - Hi-Fi Corner - Naim Audio - Community
Naim Unitiqute -- repair or cut my losses? | Audiogon Discussion Forum
Naim gebraucht, Geräte mit Display - Langzeiterfahrungen, Kaufberatung Stereo - HIFI-FORUM (in German)
http://www.hifi-forum.de/viewthread-33-1036-678.html#34185 (in German, #34185-#34213)

The actually question is, what is the exact reason therefore and whether sustainable self-repair is possible by replacing the associated parts (Naim Audio unfortunately recommends - like many others - always urgently not to lend a hand and invest the 300 to 400 € costs for genuine repair service).
Thank you for your advice

Hi Members.

Hoping to get advice regarding suitable Soldering Irons for Loudspeaker crossover builds
I suspect I'm using unsuitable tools.

Currently I have 2 Scope 25 watt MH25 Soldering Irons.
Are these suitable?

If not which models/specifications should I be looking for?
As a non professional I'd be looking for something not only suitable but also affordable.

Thanks.

Cliff

Goodday all,
I am looking for a Triac replacement for a Smor5g42, It is part of an X drive like Carver is using in their power supplies, I think it is a 500mA jobbie.
Help appreciated !
Regards
Jan

I have a Micromega Solo CD player which is not working. When turned on, it will start to rotate counter clockwise at first hesitantly and then faster. It happens with the lid open or closed ( a top loader) and also with a CD in place

I noted there is some slight vertical movement in the lens when it is turned on - but I cannot see the normal red glow on the laser when viewed from the side. Sometimes the laser assembly swings back and forth with CD in place.

I have noticed there is about 2-3 mm of vertical play in the spindle

It has a CDM4/25 transport fitted - I have tried cleaning the lens and checking all of the contacts. The 33uf cap on the servo board has been replaced - still it runs backwards!


I would greatly appreciate and advice and suggestions for sorting it out!

Regards Dave

I need a schematic diagram of this compact disc player models in top loader version
for attachment 4, 5 and 6 in high resolution open this URL:
Mcintosh MA6400 ????, MicroMega Trio CDP ??? ?????(Wilson Audio),????(Wharfedale),???(MARANTZ),??(JAMO),??(ONKYO),??(TEAC),????(JBL),?????(AUDIOPRO),??(KEF),????,????(Nakamichi),???(Philips),??(ARCAM),

Hey,

i decided to DIY my next DAC and kinda wanna share my jorney here and kinda wanna document it for myself...

i will keep the parts list updated here:
-------------

Case - https://modushop.biz/site/index.php?route=product/product&path=171_229&product_id=158 with inner baseplate for 70 euro
EMI filter - https://de.aliexpress.com/item/33030666632.html for 12 euro (nice pcb layout)
Transformers - toroidy audio grade
usb to i2s - either jlsounds or amanero derivate
dac - probably jlsounds ak4493

-------------

i might also do some pcb"s on my own, the rectifier board seems easy todo and probably better than chinese bought ones..

still alot to go... stay tuned

Hi everyone, I intend to design some pcb for Mr. Walt Jung's shunt, I took the original schematic and added the reference GLED431. My idea is to design a pcb schematic and then make it public for those who want to print it themselves or modify it since there are none. I share the schematic I created, I would like to know if there are improvements to be made and if you need to have specific precautions in the design phase of the pcb. The PCBs that will then be created will have the rectifier part on board, and perhaps even a transformer for each branch. But let's go in order before we establish the goodness of the scheme ...

For reference : https://refsnregs.waltjung.org/.

Hi all,

Does anyone knows what is the difference between PCM63P-J and PCM63P?

I have a Rotel rcd-971 with PCM63P dac chip and a Parasound D/AC1000 with PCM63P-J and I would like to know if one has better specs than the other (couldn't find in the spec sheet) or maybe they are both exactly the same.



Thanks

This amplifier is based on American Beauty Buffer https://www.diyaudio.com/community/threads/1w-7-components-american-beauty-buffer.331274/
The clever idea is by @diegomj1973

Suitable for 8-64 Ohm headphones.
Distortion is low THD 0.0001%
The +/-12V supply should be well regulated. Use voltage regulators.

Hi all, I bought an active subwoofer, an Alpine SWE-815, and am using the components in a wooden box I built, but am not sure which way to fire the 8" sub.
Here are some photos of the install location. It could fire right, left, or forward toward the cubby door / seat.

Thanks!

Thinking about getting a higher current supply for testing amplifiers under load. Car amplifiers that is, .

I have a prism sound dscope and am able to do power sweeps etc, been doing it for quite awhile.

I'm constructing 4 banks of a bit over 1000W capable 4ohm loads that are fan cooled. I'll be able to parallel the banks up later. They are 45ea of the vishay 2.2 ohm 25 watt resistors. 9 series/5 parallel fwiw. Should be pretty nice.

I currently have a tekpower 15v 60A (and 5A 30v tekpower for debug). Kind of limited for the higher power amps I'm repairing, especially if I want to test below four ohms.

Spark Usina makes an interesting offering out of Brazil. Will do 220A at 15v. Decent price.

I know everyone will suggest this and I've built server power supplies and have one. I haven't figured out how to bypass the overvoltage. So it's only good to 13.8v which isn't ideal. Pretty common to hit the overvoltage barrier with sever supplies I believe.. I used this one before I got the high power tekpower.

I have access to 220v 20A at my workbench fwiw.

Wondering if I'm missing another option? Would like to be able to do 200A at 15v at least. Needs to monitor and display both current and voltage too.

--------
Ended up buying x3 of HP dps-1200fb hstns-pd19 and modifying... This thread became kind of a how-to..

Hello, after i built my first numpad which works, i now want to see if i can build myself a compact microphone preamp, as well as dac/amp for my headphones as well.
I want it to be a digital one, so i can add software modules/addons for said software without needing more than a processor and enough ram to handle all the tasks it needs to do.
It will need: 48v phantom power supply (don't know how this stuff works yet, but i learn as i go along), Rotary dials, and sliders for microphone EQ/low, mids and high's, as well as volume/gain
For headphones: dac/amp components for up to 600 ohm, if i ever get heavy driven headphones, as well as EQ sliders for it for low mids and high's as well. Maybe even a physical section of sliders to adjust EQ that way.

Headphones will be 3.5-6.35mm aux, mic will be XLR.

Is this accomplishable?

When winding a mains transformer with center tapped secondary the outer half winding will be larger than the inner half.
Also the wire resistance will be greater than the inner winding.
How much will this affect the voltage?

My Nakamichi PA7II USA version was in beautiful aesthetic condition and functioning beautifully in our home. I check bias about every 180 days, and set it to 40mA. It has been used about 6-8 hours a week with no troubles at all.

A few weeks ago I lent it to a good friend whose amp started making noise. He took that amp to his tech, and I installed my amp into his system to make sure it wouldn't be damaged.

He used it every day for over a week, then decided he wanted to change speakers and preamps. He noticed after that the amp dropped volume in the left channel, and the right became distorted. He indicated that he shut it down immediately, and not wanting to return it to me damaged, and knowing I was in the middle of rebuilding two APT amplifiers and working on other projects, he took it to his tech.

A few days ago the tech was diagnosed with cancer, and returned both amps to my friend, but unfortunately, my beautiful Nakamichi is now a basket case.

The output transistors were removed, and a few caps were removed from each amp board. The front panel limiter PCB was opened up for testing. The tech gave my friend some minimal notes of his observations, but I'm really unsure of the best way to proceed.

The tech reported that he put the amp onto a dim bulb tester which lit up but then seemed to draw less current, so he checked bias on the left, and it could not be adjusted. The red bias LED was brightly lit at low bias current, then flickered out when the bias pot was raised. The right amp board then started smoking the 5R1 Zobel resistor, so he shut it down. He also noted the VAS transistor area of the board was running hot, so he installed some small heat sinks.

What I've done so far is to replace the missing electrolytic caps as well as the remainder on each board. I've also tested the output transistors with a Peak DCA75 just to find out if they were shorted, and get a rough idea of condition. The photos show the hFE reported by the Peak for each output transistor in their original positions (they were numbered when removed). They don't look great to me - many are very low, and the variance is pretty wide. Unfortunately, new replacements aren't available - the ones for sale are fakes.

Additionally, I have...

1: Checked all of the diodes using my DMM in diode check mode. No shorts or opens, but some (labeled B2 types in manual) read similar voltages in each direction.
2: Checked all small transistors using DMM in diode check mode. No obvious shorts or opens.
3: Checked all resistors. Most check very close to values specified, with a few that are difficult to measure because they were in circuit.
4: Replaced the 5R1 Zobel resistor and the poly cap on both boards.
5: Checked the power supply - no obvious problems.
6: Replaced the electrolytic caps in the limiter PCB. The 2R2 20W resistor is not burned nor are there any other bad components.
7: Re-installed the output transistors.

I then installed only the left channel (mounted to heat sink) to the amp and connected to the limiter board, and then tested on the DBT.

Here is what I observed.

The limiter circuit switches on properly, but the left channel would not bias properly. Adjusting the pot would result in a momentary increase from a few mA to about 16mA, then it would fall back to a few mA.

I removed the left channel and installed the right channel. It would not bias - stuck at about 4mA no matter which way the bias pot was adjusted. I then found 76V at the DC offset test points, and shut it down.

I've since removed the boards from the heat sinks and the output transistors from the boards again, and have tried to re-measure everything on the board, but can't find anything that leads me in the right direction. I don't truly understand the Stasis topology, and can't figure out why there would be 76VDC on the offset test points without having either shorted output transistors, or some other short on the amp boards, but I can't find any evidence.

This is a beautiful amp with a clean, straight chassis and otherwise great condition, and it has real value to me, but I am not sure of my next steps. I've rebuilt or repaired 11 other amplifiers and learned from each one, and don't want this one to be the one I can't bring back to life.

Like others I hear from here, my brand new edcor xformer has a very loud buzz .. I have been around enough similar transformers over the years to know its not what a high quality/functioning xformer should sound like. Talking with edcor did not leave me feeling sending it back was worth the hassle or cost. . Has anyone had any luck sending back buzzing edcor xformers? Anyone make high quality xformers that are reliably quiet? I am not super price sensitive though good value would be appreciated...

Not sure if I’m asking in the right place but here goes. I frequently replace TO3 and MT200 output devices with TO3p and TO247/TO264. Generally, the only complaint about doing this would be the smaller heat spreader. I was trying to figure out how to get around this, thinking of making aluminum plates, the same shape as the original devices, but I’m still at the mercy of the thermal compound then I saw a product on xraytonyb’s channel and realized it was exactly what I was looking for. Instead of using aluminum, I would use copper and then solder the device directly to that plate. This product was developed by Hoppe’s brain.




This method is likely the best you were going to get to replacing the larger heat spreader. As soon as I saw it, I was thinking of also making them for TO3 and the batwing transistors using TO220. wouldn’t you know I found that he was also developing those. So instead of buying a sheet of copper and cutting them out myself I figured that since JLCPCB offers boards that use a solid copper substrate I could have them do it. Basically, I would be ordering boards with no traces on them, I don’t even have to have a silk screen. I would be completely happy with just copper cut outs.



I am replacing some right now and they would definitely be handy. I would buy them directly from Hoppe’s, but I use these frequently enough that I would like to purchase around 100 of each shape and ordering them from him would be very costly. So to make these files and send them to JLCPCB would Kicad be the best option? I don’t know what the best/ cheapest solution would be have them cut out all the shapes individually or have them ship me aboard where I clip them out myself with a pair of snips, meaning have like 20 to a sheet that I cut out on my own. Just looking for guidance really.

If there is anyone that would be interested in doing up the Gerber files in exchange for some of the plates, I would be very interested in that as well, I don’t have a lot of experience doing this type of thing. I’m thinking that since the drawing is one dimension, basically like a cookie cutter that it wouldn’t be too difficult to do the file, but I don’t know.

Thank you,
Dan

I'm curious to learn a little about the uMar-KenSET speaker design that's been shown here. I'm looking for a relatively small speaker that will be used with my computer. Playback chain will be Focusrite Scarlett 2i4 DAC ---> ACA ---> nice small speakers that will flank the monitor on my desktop and be pushed up against the wall behind the desk.

The uMar-KenSET looks like an interesting speaker that seems to fit my criteria. Will this design perform well in this context? I figure it probably won't generate much bass (maybe wall and desktop boundaries will help a little?), but I need something that is pretty accurate on the top end for click and pop editing on vinyl rips. Open to other ideas, of ocurse, but I'd like to keep driver cost under about $100 each and keep the footprint small.

The slanty-front baffle design also looks like it might be worthwhile, given the nearfield listening.

I was pulling apart my KEF Ref 102/3s to rebuild crossovers and ended up tearing the rubber coupler which holds the woofer in the enclosure. The rear mounting screw wouldn't budge and it just spun the coupler until it tore away. I had to stick the coupling rod in a vise to break the rear screw lose. Now i need to figure out how to repair or replace the rear mounting coupler.

Any ideas where to find or fabricate a replacement?

Hi gang.
A guy in the German Visaton Forum did a mod to the Visaton BG20 that is worth sharing here.
Maybe it has been covered but I did not find it with the search engine.
The basic mods like additional magnet on the back, basket damping and felt rings in the center of the voice coil suppose to benefit the BG20 allot but
this mod seems to make the biggest upgrade to the unit:
Applying Dekalin a visco elastic sticky sealing paste onto the ridges of the surround exhibit the following measured results.
First photo is the stock unit
Second with only the inner ridge treated
Third with two ridges treated

Hello everyone, I recently built some bookshelf speakers which I simply called "Classic 25" due to the shape, design and use of a pair of widely used Seas 8" + 1" drivers, the CA22RNY woofer and the 27TFFC tweeter . Among the various audio constructions that I have made over the years for my personal enjoyment, I decided to show them to you because, in my opinion, they sound very good, they are easy to build, practical to use and have a cost which, although not low in absolute, it's pretty low compared to what they offer.

Let's start immediately from the end, the sound. As you can see, the filming takes place in a very ordinary dining room, without acoustic treatment and with some critical surfaces (mirrors, glass cabinets, tiles), measuring 25m2. The Classics are placed on a sideboard (bookcase, desktop, TV stand, etc.) a few centimeters from the back wall and two meters from each other.

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My Denon DVD2900 has a damaged slide gear for loading mechanism. I found exact part number in service manual, but google search came up with nothing. Is anyone selling Denon parts in Europe? I already asked Denon Netherlands and looking for other ideas while waiting for an answer. It's the part marked as 11 in the picture. Part number 9KC 1G00 3 (SLIDE-CAM).

I found this diagram for a Harman Kardon 730 rebuild and a lengthy discussion about modding the phono stage to an RIAA signal opposed to the IEC signal it was designed as (for some reason).
Has anyone done this mod? Results?? Cheers!

Hello guys, a couple of weeks ago i took two amps from a friend, both were in someones else repair “bench”, this is what my friend told “ amp was bought as a bargain, took it to a guy to install the fromel kit, after that amp has NO preamp, and also switching its sketchy (when push change channel light turns red it’s supposed to be yellow, and when you press more drive its glowing lighter then completes turns of) so this is what i have done

~ cleaned all solders and repaired some burned trails
~checked all components and steps on the fromel kit, they tested ok and they are all correctly installed.
~ i measured R78 R79 im reading 47.8v from one side which is good, but am reading 3.0v and 2.9v from the other side so all low power supply its wrong.
~im not getting readings from U1 just the same reading on pins 4 and 8 3.0v 2.9v
~ i did change Q4 channel switching behave ok but its again down, maybe other component its shorting taking Q4 down?
~i do have clean audio on power amp in/send , so i do suspect problem is on switching related, also i did not notice anything else in bad shape.

As a note im suspecting this amp was already on bad shape, I don’t think the last guy repaired to stock condition and then modified, i do think somehow he was hoping after the mod the amp worked, anyways now its my problem so let me know if you guys can chime in with some ideas, thaaanks a lot

Hi,

I would like to know if anyone has already uploaded some "user" libraries online, to integrate the "standard" libraries that LTSpice 24 automatically updates.
As you know you can't modify the "standard" libraries, because they are overwritten at every update of the libraries, so with the latest revision LTSpice has the possibility to integrate other "user" libraries to the "standard" ones.

I've done mine for mosfets, but I would like to know if someone else has done something similar.

Thanks,
Roberto

Hi,
I am building cabinets for my 604e w/ GPA crossover. I'm using 3/4" birch. With much due respect does anyone know if I could ask Greg Montfort for some much needed advice?