Inductive interaction/coupling between inductors is many times underrated/ignored and some times just tested on how the inductance changes between coils which is just one part of the real problem.

I was researching about crossover inductors position practices myths and facts(see here) on how audible and at what power levels this really became a problem but I was unable to find any A/B blind tests on the net.

Then to make the long story short(sorta), I was completely chocked on my own findings, I was able to drive a compression driver connected to an 0.7mH 20AWG inductor by exiting an 1.5mH 14AWG inductor and placing them just few inches in the lay-down position, the closer they become the louder the compression driver becomes, and in the recommended position I fount that putting the outer windings out of phase is the least affected position.

My tests was very simple and no expensive measurement gear was required.

Used parts list if some what to reproduce the tests(parts don't have to be exact):
1) An 1.5mH 14AWG inductor.
2) An 0.7mH 20AWG inductor.
3) An 33uF MKP capacitor.
4) An non-inductive 20W resistor.

I've used a piezo compression driver for the test as those things are sensitive but I believe any sensitive 8-ohms CD can be used as well, also I've used a standard Class A/B amplifier and put some load(fast electronic music) into an 12W 5-ohms resistor until the 1.5mH inductor made some electro-magnetic field to make an screw driver vibrate inside the hole then I've stopped increasing the volume, at this point the 12W 5-ohms resistor is hot to the touch but not burning, to my surprise I was able to even hear the kick-drum into the compression driver😱.

To conclude this simple test I believe that even 4 inches of proximity is not enough for lay-down oriented crossover coils, also the most affected are the users of high sensitivity speakers such as compression drivers.

Here is the simple test diagram:


Here is the recommended inductor position with coil outer windings out of phase:


Here is the modified crossovers from my old bookshelf speaker build, the midrange is way cleaner at high volume and the center image is now wider and immersive:


Regards!

Hey everybody, I just finished putting together a 2 way crossover design in Xsim. I have generated my own .frd files with the drivers installed in the cabin, and traced the .zma files from the manufacturer's specs.

Overall I am satisfied with the outcome. But before I give it a go, I'd like to hear your remarks for I am an absolute beginner. I am especially curious about how you would interpret the impedance graph, given the peaks are rather high up on the scale. Should I be worried or is this fine?

.

For reference, I am attaching the manufacturer's graphs for both drivers:

sb15nrxc30 (8 ohm)


Morel MDT29 (8 ohm)
.

Thank you!

I’ve been using freeze spray to identify resistors that are cold sensitive, but I’d like to be able to test individual components.

I'm rebuilding two very trashed Vermona L9033s and wondering if can i fit an EU mains cable into a 6.35mm jack like this? Thanks in advance.

Warning: Noob questions incoming. I'm planning on investing quite a bit of time and effort into the construction of a beautiful cabinet, so I need some help deciding on the material. When it comes to MDF, I'm a bit concerned about it absorbing moisture from the air over time or that the construction might not be as strong as plywood and could get wobbly over the years. Plywood should be a superior choice in that regard, but I'm unsure how its lesser density and uniformity affect performance.

If I go with MDF, would applying a sealant on the inside and veneers and finish on the outside seal it hermetically, making it last longer? I'm planning on keeping the speakers for a really long time, so longevity and build quality are important factors to me. Perhaps I'll even fit Anthology III inside the enclosure in the distant future 🙃.

Also, how difficult is it to maintain the speaker and replace the dampening on the inside, since it's probably the first thing that will rot out over the years? Another question I have is regarding the slightly rounded edges that are on most of the Anthology builds. How would the speaker fare without the roundover? I've read that the roundover is too small to have a significant effect on refraction, but I figured it would be best to ask you guys.

Thank you for reading!

I found that there are a few of these for sale on eBay lately. Now 40 years old the grease has thickened into a sticky glue that impedes the motion of the tone arm on the rail and the little belt gets stretched so it often doesn't work. Fortunately the belt is readily available and the grease is pretty easy to clean off following videos on youTube for similar models. I could not find instructions for how to align the tone arm or clock frequencies on the web, so I bought the service manual. As it has no copyright notices anywhere to be found on it, I scanned it and have attached it here. Technics SL-Q5 Service Manual.

Hi,

I would like to ask for advice on what of the 3 Aikidos that glassware offers (octal, noval and 12v) is easier to put together. I am a long time audiophile and I know how to solder and I am learning how to read a schematic, but I have some doubts as to what is the best Aikido line stage from those 3 you offer for my specific needs.

For my needs, I just need one single line level input, because I mostly listen to music from my DAC.

Regarding those 3 Aikido's, are there any evident differences in sound between the ones that require a power supply (Octal and Noval) in comparison with the 12v one?

How hard is it to put together the Noval or Octal kit with the PS-21 that glassware also offers?

Thanks,

Alan

I’m not sure is this the right place for this. I bought a known broken X250. Right channel is out. I’d like to fix it myself. How hard of a repair? Where to get parts? Story in pics below.

Hi there,

Way back in the past, closed box speakers were frequent. What are the benefits of a port ? It goes further down. But is a ported enclose as punchy as a closed one ?

Walter

Wondering if anyone has a schematic or other info on this Epperson / Waters preamp line stage, apparently designed for the Dynaco PAS2/3 series?

Thanks in advance,

Jono

Clearing out odds and ends.
Bought this NOS from vacuumtubes.net a few years ago. I have no use for it now. Works great. I always ran my RCA in place of other 6SN7 brands so this has virtually no usage whatsoever.

$30 + $6 shipping.

I also have a pair of Sylvania 5U4G that I'd throw in for free if desired.

Accuphase model "E405"-clone and Music Fax Power Amp "F18" and "A-1000" from Kaisaya HiFi Audio - Schematic wanted

For the follow products I am looking for schematic diagrams:

2pcs E405 Gold Seal Tube Post Grade Amplifier Board Class A High Power HIFI AMP Circuit Module 200W MJ15024G/MJ15025G/2SA19-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group

E405 power amplifier board (reference circuit Accuphase) (1 pair) in E405 power amplifier board (reference circuit Accuphase) (1 pair) aus Schalterkappen auf AliExpress.com | Alibaba Group

MJ21195 MJ21196 MJE15032 MJE15033 BC546B BC556B WIMA MKP10 2.0 250W Music Fax F18 Class A Postposition Power Amplifier Board in MJ21195 MJ21196 MJE15032 MJE15033 BC546B BC556B WIMA MKP10 2.0 250W Music Fax F18 Class A Postposition Power Amplifier Board aus Verstarker auf AliExpress.com | Alibaba Group

MJ21195 MJ21196 MJE15032 MJE15033 BC546B BC556B WIMA MKP10 Musik Fax A1000 2,0 60 watt Klasse A Endstufe in MJ21195 MJ21196 MJE15032 MJE15033 BC546B BC556B WIMA MKP10 Musik Fax A1000 2,0 60 watt Klasse A Endstufe aus Verstarker auf AliExpress.com | Alibaba Group
MJ21195 MJ21196 MJE15032 MJE15033 BC546B BC556B WIMA MKP10 Music Fax A1000 2.0 60W Class A Power Amplifier in MJ21195 MJ21196 MJE15032 MJE15033 BC546B BC556B WIMA MKP10 Music Fax A1000 2.0 60W Class A Power Amplifier aus Verstarker auf AliExpress.com | Alibaba Group

Thank you very much for upload.

The brand "Music Fax" I have never heard before, but the board of power amp so as the completly device looks both very impressive and well made.

I've come into a few hundred 2SK389s as well as few hundred 2SJ109s. I want to try to match them up and then sell the pairs on Ebay.

I've done JFET matching before but not with IDSS method. What I have done, for sensor applications, is measure the VGS for both sides of the FET at the bias point, or very close to it, of the final circuit.

What is typical bias point for audio applications? I was thinking 9V and 5ma, but I really have no idea.

Here i have Aluminium Case that is used for Class AB Amplifier. I buy that aluminium case and drill a few holes inside heatsink to mount audio amplifier. But i sell that amplifier to member here in diyAudio forum so i got the case that is like new, without scratches or any phisically damage. It comes in protection box that is ready to ship for happy buyer here, and comes with softstart inside box and dual bridge rectifier, volume aluminium knob and push button for on/off that have LED inside.

Heatsink size is 42cm x 13cm x 32cm and are two heatsink, each at one side of aluminium case. From aluminium plate is 8mm thickness and it comes with screws and all accessories that came with the box.

These heatsinks can cool 200W/8R Class AB or 40W in class A, so it is intended to use as audio amplifier case with nice looking style and LED push button for on/off.

At rear it comes with golden speaker terminals, and integrated fuse inside AC conector from rear side so user can change fuse if it is needed.

All in all, very nice aluminium case with nice look and performance for Class A or Class AB project.

Price is €232,00 including free shipping to EU country and paying with paypal. PM with your shipping address and i will replay with my paypal data. Shipping will be with tracking number to buyer address.

I’ve got four of these driver new in the box that I am not going to use. I’m selling them cheap as I don’t have the space. I want to get $350 for them. Local pickup. I can meet someone to swap them but no shipping them.

Thanks

All,

I'm currently into constructing a new armboard for my all DIY turntable and Schröder Clone tonearm.
Here's the history.

I started out with an armboard entirely made of aluminium.


Sound was quite good - until I tried making an armboard from Panzerholz (same material as the plinth is build from):

The first version was without the copper disks. The soundstage was already way better than with the aluminium armboard - but it was lacking bass.
The two disks glued together with a viscoelastic glue cured that.

And now I beleive that there is / may be some potential left that I can unearth with a proper approach.

What I did was calculate the resonance freqauencyof the tonearm based on the effective mass of the tonearm: 8,05Hz.
As I read in one of the few threads that seem to be reasonable if it comes toi matchng armboards to tonearms, the mechanical impedances of both should be a match.
So I've calculated the mechanical impedace (with a little help from chatgpt) Zm = i1,752Ns/m based on the resonance frequency of the tonearm.

And this is where I'm lost and stuck. If I now would like to make the armboard of Panzerholz or a composite of different materials - say Aliminium/Panzerholöz/Aluminium - how would I calculte it's dimensions?
Or am I entirely wrong with my approach?

Best Stephan

Bought it broken to compliment vintage Meridian pieces. It was exhibiting typical TDA1541 crackling sound symptoms and as a transport it only played first few tracks and refused to go forward. I thought it will be rather easy fix but I was wrong. I replaced TDA with a chip from donor board I vaguely remembered it was working. Voltages seemed correct but it didn't help. There was no output at all. Frustrated I pulled the chip and put it in my DAc .It was working fine . I checked old chip ( S1) and surely enough it was fried. I put it back , checked and re re checked and again nothing. I cut out Meridian output IV stages and installed resistors to check nothing at all. Damn it. Since no schematic is available decided to use machine as a transport only and pulled the chip again which pretty much damaged fragile plated throug PCB tracks. Still salvageable and I have 28dil socket on order. Back to transport. Thinking that recap will fix the tracking issue I took it apart and replace servo capacitors, Psu caps and all el caps around transport serving chips . Nope . The mech is rare as hen teeth CDM4/21 . It's not an issue with clamp since Meridian is using custom clamping arm where nothing wears out. It's just a plastic platter spinning against flat metal surface. Player plays 3 to 6 first tracks then servo makes some screechy sounds and the playback stops. I didn't get to mechanism own control board with potentiometer not seeing any capacitors there.
Anybody familiar with quirks of this machine. I replaced SA7220ap and it made no difference. Bummer

Hello, i will update the clock to SC-Pure. Musik play from Qobuz and Tidal with MConnect from ipad.
DAC is Holoaudio Spring 3.
Must i buy 1 clock 45 or 49mhz or need i 2 clocks 45 and 49 mhz? I dont understand this?
thanks

I know that midbass is the hardest thing to fix in car audio , but even outside or in house my subs didnt hit, they where just loud af.
i had only 12" subs. Rockford t2 and alpine type x. The t2 was so nice in a small box
Why a 1k sub can't hit you in the chest and a crappy 15" 100w pa driver can?

is Sd my problem? Or is the vas and cms, mms. bl

Now i have an eclipse sw8122, 12" 140gr mms, high cms with 90L vas! 21bl, 500w rms on paper but can do a little more.
Is the same, so is not that. This eclipse is a very efficient sub, qts is 0.3 so the box recommendation is small. Is a nice sq sub

Or is just my taste in old school subs?



(I am buying old subs (only in good shape) because they are cheap, and i can sell them for the same price or more. New subs can be expensive, i am from europe, we dont have cheap good subs brands like in usa)

So...I have my drivers, I've tried a few prototypes, and I feel like it's time to get serious and I need to choose an overall geometry. I'm new to this and could use some help narrowing down baffle approach. I would say complexity and materials are irrelevant as I have access to CNC and design experts.

One main thing I don't fully understand is mounting the drivers. Rear mounting with chamfer or round over vs front flush mounting. I guess if someone wanted to give me some Coles notes on that I would appreciate it 🙂



I'm doing 18" (SB audience bianco18sw450), up to about 80hz, then 12" (jbl123a) up to... probably 500, then wide range (sonido 096 field coil)to 8000, then a tweeter/super tweeter, probably rear firing. Or I may let the wide ranger go all the way with no tweeter, not totally sure yet.

It is active and will be using minidsp for the two woofers so I can eq as needed.

Here are some primary options as I see it...

1. Wide baffle all the way, around 20" wide and around 45" high, with gradual round over on the edges, similar to the Sonus Faber Stradivarius U frame or partial uframe for the 18".

Reasoning: the wide baffle with large round over seems to give good defraction characteristics for the higher frequency. Pretty good looking if a little large.

2. Do the midrange completely baffle-less mounted somehow above a more traditional flat, wide baffle for the woofers.

Reasoning: no baffle at all for mid-high has best defraction characteristics...? The woofers will appreciate some baffle for cancellation purposes

3. No baffles anywhere. Nothing extends beyond the drivers.

Reasoning: again, defraction characteristics and off axis for mids and highs is good. Lows have zero baffle coloration. Also zero cancellation mitigation so needs a lot of eq.
Can look pretty cool.

4. Triangle. Baffle gets progressively larger as the drivers get larger. I could imagine benefits for off axis response similar to offsetting drivers due to the fact that the angles are changing for each driver, vs a parallel+perpendicular shape of a rectangle. Can look good.

5. Separate, different shapes baffles. Sort of looking at the pap construction but using the size most suitable (determined...with edge software?) for each driver. Similar to the triangle idea but with rectangles basically, and more flexible on size since each is separate. Large round over on all angles would perhaps guide much of the wave off the baffle before it hits the next baffle/driver?

Other factors, possibilities:

• mount drivers in felt only, inlayed in a baffle
• rear mount with drivers just barely touching baffle to reduce vibration

I may be wrong thinking in some, most, or all of this, because I'm new and dumb...

I’m looking for the tube output stage for “DAC END”
Also the power supply for it.
http://www.audiodesignguide.com/DACend2/

Thanks

I bought some headphone amp boards from a local electronic store with quality parts and a really good design, but I could use some help figuring out how to increase the gain for some more output. I currently use two pairs of headphones that are 250 and 300 ohm and I find myself having to turn the volume up 3/4 of the way for normal listening levels where my Whammy I can't even get to halfway.

The headphone amp boards were supposed to come with four LME49710 but two were missing. I am instead using Burson Vivid opamps (V5 pair & V6 pair) now in all four positions. I am using a VRDN set at +-15 Volts.

I am wondering if I NEED to use LME 49710 in all 4 locations (or maybe just in the inverting circuit) to get the unit to perform correctly or if I can change a couple resistors to increase the gain without changing the distortion. The part of the circuit I believe I need to focus on is this one. Could I safely change R10 to 6.8k ohms to result in a gain of 10 where previously it was 5.9.

Or, should I adjust the gain in Stage 2 where it is set to only a gain of 1? I have included the full documentation of the headphone boards in the attachment.

Any help is appreciated here. I really like this circuit but could appreciate it more if it had some more UMPH!

The datasheets for Mitsubishi jfets do not exist on the internet, does anyone have the databook?
Thanks,
Alex

Hi,
I would like to use a simple high voltage regulator for a SE project.

I came out with this preliminary schematic, where the feedback of the output ripple to the gate of the main mosfet (M1) is given by a mosfet (M3) loaded with CCS (M1) to maximize its gain so its correction (idea taken from @SpreadSpectrum Corona amp, where he loads a pentode by a CCS to maximize its gain and apply more nfb).



On simulations, supplying 100 mA with a 20Vpp ripple at infeed I get 600 uVpp ripple at its output, that is a 90dB reduction.
It seems too optimistic, so... what am I overlooking?

I know all safety measures for turn on/off are missing, but that will be checked and then asked later on.

Thanks in advance

This questions specifically involves the S5151 and S5151R which are dual diode devices with either common cathode or common anode and the pair are used in many vintage pieces of equipment to rectifier the AC coming from the secondary windings of the power transformer. In all the years I have been doing this I have read, been told that they are 5A diodes. In a pretty much identical case is the SS3 and SS5, the SS3 being rated for 3.5A and a smaller version of the package and the SS5 being rated 5A and the same size as the S5151. Unfortunately there are no data for the S5151. There are some threads I came across where members were asking about changing these out with discrete components and members like Echowars and Avionic which definitely know their stuff recommended 5 amp diodes as replacements like the HER504.

So I showed my replacment of these dual diode packages using MUR550 as I wanted ultrafast soft recovery diodes in place. They are 5A 570v rated. There is one full bridge for each channel of amplification on a Pioneer SX-1250


It was then brought up by another member, I won’t call him out (hopefully he’ll respond here, but he too knows his stuff as well), that the S5151 may not be 5A rated. He brought up the fact that the SX-1050 uses a 20A rated rectifier, so 10A per channel for less output power. So why a smaller rectifier for more power? I suggested that the rectifier may have been overkill, they could have put a 30A or 40A in there.

I then brought up the fact that the SX-950 which is 85 watts per channel, so 170 total (10 more watts total than each channel of the SX-1250) used a quad of the SR3AM diodes, both channel share the one bridge rectifier. The SR3AM is rated for 2A continuous or 3A with a heatsink which they didn’t use.

He then brings up a conversation that he was having with someone wanting to use 1N5404 (3A rated) in the SX-950, but he felt they weren’t adequate and recommended the need for 6A rated diodes. Why would an amp that came from the factory and has been working for nearly 50 years on 2A rated diodes (3A with heatsink) need 6A? The SX-950 runs at lower rail voltages than the SX-1050 and SX-1250.

So I figure if the SX-950 can make 170 watts output using 2A (3A with heatsink) diodes why can’t the SX-1250 make 160 watts using 5A diodes? I’m still convinced that these S5151 devices are 5A. I set up the bride rectifier so that I could measure the current in the SX-1250 and into clipping the amp heavily the highest I saw was a little over 900mA, but of course I wasn’t seeing peaks.

Regardless I put the SX-1250 back together with these new 5A MUR550s installed and it’s been playing for over 24 hours straight, blasting it pretty loudly during the daytime hours playing into my ADS L1590/2 and ESS AMT 1B. They may not be the most demanding load, but it’s been perfectly fine.

But for me it’s down to the fact the SX-950 makes slightly more power total on a lower current rated bridge rectifier and that for as long as I can remember the original has always been thought to have been a 5A device.

Thoughts?

Dan

I have been looking to pick up some 2SK117s for some time, but knowing they are no longer produced, the likelihood of getting fakes are pretty high. I know that things can be faked to make the item look as authentic as possible, but I found this seller out of Japan, has 100% positive feedback, and if he indeed has the original box and such, I would put my money on these being authentic. Does anyone have the same opinion of them?


I’m wondering if I even need them though. I know this is all circuit dependent, so in the end I guess really wouldn’t know. I have at least a couple hundred each 2SK170 and 2SJ74, that I know with absolute certainty are the real thing. In most instances would the 2SK170 be a good sub for the 2SK117? In what instances would it not be a good sub other than circus that use higher than 40 V? Another option I was thinking of was using the SMD part 2SK209, putting it on a small adaptor board. It does have about half the dissipation of the 2SK117 though.

I like having large quantities on hand, especially if things are no longer available, which is why I have a couple hundred each of the 170/74 combo. So I don’t mind buying 200 of the SK117 and if I were to get the 2SK209 I would grab a couple hundred of them as well.

I was hoping to get opinions of others in here. If those 117s do look authentic would it be best if I grabbed those or do you think in 99% of instances the 170 will work? Or with the combo of the 170 and the 209 I should be good to go?

Dan

hi everyone.
instead of using a fixed high gain electronic module (whatever the technology) and an attenuation pot (whatever the technology) , why not have a preamp circuit that exhibits from the start the exact gain needed according to the source output level, amp sensitivity and listening level chosen ?
For instance, with today's sources and amps and at usual listening level, you often need a say 0dB gain preamp so your common and possibly very expensive 20dB line preamp has -20db of attenuation in front or in tail. Not the shortest road ... As we say in French : "Quand le tabouret est trop bas, on coupe les pieds du piano". By the way, most line preamp designs have in reality an enormous gain that is reduced to around 10 by the use of negative feedback.
Here is a three BJT tunable gain preamp -very messy- prototype that gives 20dB of max gain, very large bandwidth and very decent output impedance. No feedback used, no regulated PSU but cross wired double choke on balanced bipolar PS and by design very low power power trans instead (definitely not the modern trend !), among other things.
Considering the very encouraging sonic results, I believe the idea is worth digging.

Laid this out for 12x8x2. GZ34 top left, PT to right, Lundahl 1673 choke, 6SL7 center right, 2A3 bottom left, Hashimoto H-20-7U to right.

2” height should be enough room for internal components. I’m not using those polish paper-wrapped capacitors, so the electrolytics are under 35mm diameter.

I figure input in the back, shielded into 1st stage, RCA jack to front SIDE - this will be for RIGHT channel, left channel will be mirror image.

From experiences with other amps (Tektron 2A3/50IS/300b and a homebuilt 300b, it doesn’t get THAT warm inside to worry about, but I’ll leave some space around the sockets for air flow.

Any suggestions about placement, spacing? Go with a 16x8 or 17x10?

Thanks in advance.

Norm

Hello

Recently I made myself a 6 Channel amplifier to put use in my car. The amplifier board I'm using is CS8673 chip BTL Mono output 80W peak x6.

The input signal configuration is, from single pair of stereo RCA input, 2 channel received Right signal, 2 channel received Left signal. These 4 channel I use I cable for ground with continuous wiring. The other 2 channel received low-pass sub signal from different single pair of RCA input coming from sub filter crossover. or basically 2x Left + 2x Right + 2x Subwoofer

Forget the 2 sub channel which working perfectly fine. Now the 4x stereo channel board have some issue which is the output sound level is not balance. 1 out of 4 of the channel produce have lower volume.

I have retested the amp board that has lower volume externally and it just working fine. What could be the cause here? Is it because the input power reduced because I am sharing audio input signal with 2 amplifier board? Or because each amp has different power supply cable lenght? Or because the last or farthest amp from ground received less ground coverage?

Any expert can give advice how to make the sound output balance. The overall sound quality of this is quite good and. Thank you.

I don't want to reinvent the wheel, I want to build something someone else has already figured out that sounds really great.

Honestly, these speakers are going to be 95% HT, as I don't have time at home to sit around listening to music (and I do that all day at work), and I have several pairs of great headphones. I do want them to sound amazing for music, because in my opinion most "HT" speakers are loud and don't sound great. With a newborn, loud isn't in the future plans anyways. Currently, I have a Paul Carmody Sunflower Center Channel tucked in the entertainment center. As you can see from below photo, I don't have a lot of room between the entertainment center and the wall.

What I'd like to do, is build a pair of Rythmik 12" subs for each side so I get stereo bass, and stack something on top. I think I'd like to build something that I can modify the cabinet dimensions to make it shorter, so once it's on the subs it'll be the correct height. Is this a bad plan?

Any recommendations? I'm sort of leaning towards the Zaph ZRT 2.5 way, but I'm okay with something a bit less expensive.

Thanks!

This is weird.

I've tried to make contact with this Indian company but no luck. I know we have Indian members and hopefully one of them can help.

This is a big Indian company and they make among other things some excellent water purifiers but I simply havn't found a way to make contact with them.

I w to know if I can buy one of their water purifiers - are they available in the EU or if not how I can get details about the dimensions of input pipework etc. How much they cost and how much for postage, many questions.

Can any Indian member help me?

Hi,

I have a constant 50Hz humming from an AC compressor when it's almost on full power. The AC aleady got additional dampened with new rubber feet and a sound dampening enclosure, but my walls are very thin. The humming is bearly hearable but i can notice it when there is silence.
Is there are a cheap way to dampen more of the 50Hz noise?
Especially with a heavy cloud panel, or bass traps?
I could also do walls, but i'm limited on the thickness.

thank you

Hello, I have got a Line Magnetic Mini 218ia, single ended triode, 3+3 watt. The room is not small by italian standards, 46 square meters, but t is a nearfield listening set up, I'm about 2.5 meters away from the speakers.

I have been driving with it a couple of Triangle Plaisir Lymna bookshelf speakers, rated at 90 db/1w/1m, nominal impedance 6 ohm, minimum impedance 4.1 ohm. These are Triangle data. The 90 db of sensitivity may be a bit overrated but it worked well. I used the 4 ohm tap and listened with the volume knob at 9 or 10 o clock.

Line Magnetic specify that the amp can drive 6 ohm speakers, they say to try both the 8 ohm and 4 ohm taps to get a better result.

I now got a couple of Kef Coda 7 from the late nineties. Rated by Kef at 91 db sensitivity. Nominal impedance 6 ohm. I found an old online review where they measured a minimum impedance of 4.6 ohm and a slightly lower sensitivity, 90 db 1w/1m. They didn't talk about phase angle.

These Kef are more efficient than the Triangle, I use the 4 ohm tap and listen with the volume knob at only 7 o clock.

I prefer these, they have got higher sensitivity and a more british, relaxed sound. But the amplifier power transformer gets hotter with these. It is not scorching hot to the point of getting burned, just hotter. On paper these shouldn't be a very difficult load for a tube amp, should they? I can't hear problems with the bass or signs of distortion. I have tried 4 and 8 ohm taps but they seem to work better with the 4 ohm.

Is the power transformer higher temperature worrying? Should I stop using the Kef?

Thanks in advance

I bought this NAD 3020A from a member on the AV Forums South Africa for R300.00 He was selling it as spare parts, other members described it as scrap😀
It has no top or bottom cover plates and some knobs are missing.
After a good clean up, I noticed that one of the OT's had been de-soldered and from there I saw that there had been quite a bit of work done on this amp.
Motivated by poundy's post https://www.diyaudio.com/community/...t-ever-modified-and-complete-nad-3020.411511/
I was going to try and get this piece of scrap in a working condition.

Hello

I am building two Fullrange Tops
fitting to my two 18" Subwoofers (t.amp E-1200)
I will follow this cabinet design:

LAVOCE

i will use this drivers

Faital Pro HF1440 - 1,4", 120W 8Ohm
Horn RCF HF94
Speaker Lavoce WAF123.00, 8 ohm, 12 inch

and this amps

the t.amp E-400
JBSYSTEMS amp 400.2

and this DSP
t.racks DSP 206

Greetings Jonas

Hi, I was looking to design a relatively high gain mic-preamp for an audio interface I'm building. It's a USB audio interface with an ADC that nominally takes a fully differential 2.8V p-p signal, and most of the chip amps either required buffer stages or a higher supply voltage. This might not be the most practical solution, and I might just go with a voltage doubler and an INA849, but I wanted to try my hand at a preamp design. I'm relatively new to audio and electronics in general, so I would appreciate any criticism. Note that R11 is a logarithmic gain adjustment pot, and this is designed to have a high enough input impedance to also be used as an instrument pre-amp. The LTSpice and circuit image files are attached below.

---

To the mods--unsure if this was supposed to go in "Analog Source" or "Analog Line Level", my apologies if I guessed wrong.

I'm reluctantly selling a pair of AE Speakers TD6M-8 midrange drivers. I bought these about 9 years ago, and they have never been used other than to take measurements.

They are hand-made in the USA by John Janowitz and have the same over-the-top build quality as his larger drivers, including the heavy copper faraday sleeve. They really are in another league, weighing about 4.5Kg each!

Asking $AUD 350 for the pair, plus postage at cost.

Sensitivity: 94dB/1W
Frequency Response: 65Hz to 6KHz
Nominal Impedance: 8 Ohms

Suggested Enclosures:
4L – 10L vented for midbass/midrange
1.5L – 5L sealed for midrange

They are still in their original boxes, mounted to a square of ply for protection during shipping. I can post at cost within Australia.

Pulled out my old Tek 2465 Scope and the horizontal sweep seems to have gone on vacation 🙂

Everything else seems to be working and I can get vertical deflection on the calibration point. Text, measurements and x/y mode work just fine. I've gone through the service manual and checked what I can (voltages are good, cleaned and re-seated the hybrids, etc), but since I don't have a second scope, there are several things I can check. It's from the 90's, so could be a capacitor issue, but visually, things look good. Any suggestions would be welcome

Hello there,

I'm asking for some help in understanding the capacitive divider used in this circuit.

It appears that the "division" occurs at the node between the two 8.2nf capacitors to the power transformers CT.

Why does this node need to be referenced to the middle of the reservoir capacitor stack?

I wish to use this design, but I want balancing resistors for my series reservoir caps to ensure that one does not charge/discharge dispraportionately.
I'm assuming adding these resistors would mess with the DC conditions of the circuit.

Any thoughts?

absolutely nothing from the website or internet worked.. Error 432.

solution:
copy cd to a folder on the HD.
Rename or delete _isdel file.
run setup. Voila!

Hi guys! I'm looking for some advice on replacing what I believe to be an JFET that was externally fitted to an old-ish USB mic.
Quick summary of it's life. Purhased it for gaming a good while back, found it too quiet so I ripped the microphone out and directly wired it to a 3.5mm jack WITHOUT THE pre-amp. Fine for a couple of years but then I think i had some grounding issue. Behind the mic was a small pcb about 1.5 by 1 cm with a small 3 pin component on it, which i believe was the JFET.
While cleaning up the soldering the copper came away from the pcb and broke one of the legs to this component.
The mic itself is fine I just need to figure out what the replacement part is.
Unfortunately there's no numbers on the component.
I've included a picture of the mic and a link to the actual original microphone.
https://www.worthpoint.com/worthopedia/prosound-a99jb-usb-0-hq-podcast-vocal-523124932
Any help would be grately appreciated.
Chris

I'm designing a box for an 8" woofer, when I see the air speed graphs in the ducts it's always absurd values and when I fix the duct it's more than a meter in size
What frequency do you recommend for this box? I tried co, 30, 35 and 43.49 Hz
Here are my woofer settings
I tried to make it work in a sealed box so the spl disparity between the sealed and ducted box really discouraged me, as the midrange has a very high spl in comparison.

Hello--

I've got an Audio Note Kit 2.1 DAC which, when not playing music, produces a high pitched noise. If I play music, it stops. When I pause a track, there will be no high pitched whine for a second or two, but it always returns. It is volume dependent and I must turn the amplifier up pretty high to hear it. Currently don't have an oscilloscope to do any measurement, but will have a very basic one soon. In the meantime, I've used an online tone generator and the high pitched noise seems to be something like ~12 kHz.

There is a deactivated ANK forum that I have searched for help on this issue to no avail. Also consulted Brian, ANK proprietor, but did not have great luck with him on it. He basically offered to send me a new AD1865, then didn't, then said "this has only happened with 1 other kit and we have never been able to reproduce it."

So I'm here. If this is an inappropriate post on DIYAudio, please let me know and we can delete it.

The DAC can be broken into two halves: analog and digital. A single transformer feeds a digital and analog power supply.

The analog power supply is AN's "M2 power supply," which uses a 6X5 and an ECL82. This feeds into an output stage which uses two 6DJ8s.

The digital power supply is a basic Schottky diode bridge rectifier with (going by eye) an RC filter. This outputs at +/- ~9V to the pre-assembled DAC board. I do not have a schematic for the DAC board or the power supply, unfortunately. The DAC board features an AD1865N-K and a CS8414 Digital Audio Receiver chip.

The DAC board and the analog out board are transformer coupled via I/V transformers.

I use a Raspberry Pi with a JustBoom DigiHAT with Moode to stream via Qobuz.

Does anyone have suggestions for how to investigate this? As mentioned, I will have a basic oscilloscope available soon. Is there any way to determine if this originates via the digital or analog side?

Is this known behavior amongst DACs?

You can find images of the kit here:
Shared album - Kyle Karthauser - Google Photos

(Note that I am using a SS faux-tube rectifier in lieu of a 6X5 right now--6X5GT just died and I wanted to give one a shot)

Please let me know if any additional details on the issue or the DAC would be helpful.

Thanks!

Wanted to buy:

One Antek AS-1T150 toroidal power transformer - 100VA
4 Outputs:
Output 1 - 150V 0.33A
Output 2 - 150V 0.33A
Output 3 - 6.3V 3A
Output 4 - 6.3V 3A

I am New Zealand based
Thank you!
Andrew

I have bought a pair of used Hammond 1650 E output transformers. I see on the Hammond website that the colors of mine, and the colors of the wires on the secondary side, on the form on the website are different. The colors of mine are black, black with red markings, green, black with green markings. Mine were manufactured in March 2004. Can anyone help me out there?







Tilbakemelding

Google Oversetter​

Hello. I am looking for AK4490EQ chip. I need the chip to be from a reliable source - original.

Monster subwoofer driver from Adire Audio for sale. Very lightly used. I decided to go with a higher-sensitivity driver instead. I no longer have the box. Local pickup in San Francisco Bay Area preferred.


(stock photo)

Details: https://adireaudio.com/product/brahma-x-15/

I paid $824.05 after tax. Asking $400 which is over half off.

First-time post for me. I'm the AV tech at our church, and have cabinet making skills. I recently purchased a Micca M-8C 8" 2-way in-ceiling speaker for our church's front entrance foyer. We have a 100+ year-old building with Lath & plaster ceilings. Using a 16-element stud finder, I thought I located an area free of obstacles. I drilled a 3/8" hole, but when I attempted to cut two lines out from the center of the hole found an electrical conduit on one side and a ceiling joist on the other side.
I want to construct an enclosure for the speaker that will be mounted to the surface of the ceiling. I need some help in understanding the acoustics involved in speaker box construction. The outer dimensions of the speaker are 10.7" diameter, with a mounting depth of 3.5". I am imagining a box that 12" square and 4" high with slots (instead of one or more round port holes) on two or four sides, say 1/4" x some length less than 12" long. Someone indicated I need to obtain the Thiele/Small parameters in order to proceed with a proper design. I've requested this information from Micca. I'm looking for advice on how to proceed. For example, does this box need to be tuned? What do I do with the Thiele/Small parameters if Micca provides them? Thank you! Link to Micca M-8C.

not sure what to call this other then a volume pedal even tho its not a pedal. i have some questions about how to wire it and not sure where to get the information so i figure id ask here.
basically i built this little box that looks like a amp and all it does it have a on/off switch for a power bar i mounted inside, and three volume pots with three outputs. the idea is i play through two amps and this will act like a ABY pedal. the third output is just for extra options (ideally for my rocksmith cable lol),

my problem is wiring it and grounding it, i seem to get a loud buzz from the output and i think its a grounding issue, i know using two amps can cause a ground loop aswell and ive had aby pedals that made this worse so i added some resistors between the grounds, i read on google about that but im not sure even sure about that.

here is the wiring i had



this is what im building is anyone is interested

Hi guys , hoping you can help me establish the values of these 2 resistors please?
Burmester 785 preamp

Greetings from the UK, with some free time on my hand I'm back into audio electronics

Hey Folks

Have an amp here that's not coming out of standby / or going into protect.

Relay clicks when power button is pressed but led doesn't go green and no output.

Pics of board and schematic attached.

Any pointers on methodical fault finding would be a help

Only thing I noticed on the board - looks like got hot around the 'remote' connector - I've reflowed the four resistors R426 R427 R428 R169 and transistors Q404 and Q405 which also tested as expected with a DMM.

I have component tested the momentary buttons and the the two IRF740 mosfets which are ok.

Looks like the irs2153D is there as a gate driver to protect the fets anyway, and boom I'm suddenly out of my depth on this one. I'm trying to dredge up knowledge I had many years ago but haven't practised in sometime.

Haven't got a scope here, just a DMM and a reflow station.

Any help or pointers greatly appreciated.

Douglas Self Audio Power Amplifier Design handbook Third Edition. $50
Handbook of Transducers SOLD
Vinyl Book SOLD

Hello.
For sale is a large Ulveco toroidal transformer, dual 25v, 29a, centertapped, It is heavy, so Europe only.
Guess it would suit many pass class A designs.
What should it cost ? 200 euro?.

Long story. Got this vintage class-D amp with a borked power supply. After fixing the issue it went back to the agent who requested the repair. Fully functional. Its owner then requested a recap which the experienced agent duly executed. At powerup (on DBT) it went full latch-up. Sheepishly the agent (who shall remain nameless) came back to me after finding nothing amiss.

After two months breaking my teeth on it I found that the latchup is caused by the SITs not being switched off fully at powerup. Without the output transistors and the PWM in service mode (R119/69) it works like a charm. Now the latchup causes the power supply to be overloaded. Which is weird given that it would work fine with DBT previously. With the PSU overloaded the two gate supply rails (+/-120 V) don't rise enough to cut off the SITs. Which need more than 25 V to reach that point. I also found that the PWM modulator also goes in a latchup mode due to the current source Q103/53 not starting as its power rail also rises too slowly. I did manage to get it going by removing C155 (I am working on the right channel, left is still in service mode) and using an external power supply to get the gate supplies going. At first it would start reliably when switching on the external PSU but when I started to move SITs around that went south and now it is bursting or even flatlining fully latched up. I don't believe that the SITs are bad. The rush-in current limiters are both OK and when the amp does work properly get shorted with their respective relays. Apart from the plethora of PSU rails the circuit itself is not all that complicated but the chicken/egg situation has me utterly flummoxed. What is going on here and how can I fix it? It must be something silly that I am overlooking but for the love of all that's holy I can't see it.

Scope images might illustrate. This is the gate drive of the SITs. This is a successful start with the external PSU:


And here it fails:


Once the PSU rails are established the rushin relays kick in, followed by the speaker protect relays. The slow rise is caused by the first stage of the PSU, which builds the primary regulated voltage (240 VDC). This is then fed to the second stage which provides mains isolation and all the secondary voltage rails. There are no less than eight. The PSU has not been touched, only the amp itself has been recapped.

I am considering the following measurement of DAC chip linearity and conversion accuracy (having 16-bit current output DAC in mind, like the TDA1541A):
Feed the DAC with an offset binary digital signal so that only the MSB has 1, all other bits are 0. The output current will be 2 mA. The accuracy of this current should be better than 1/2 LSB. The LSB current is 1/32768 * 2 mA = 61 nA. Half of this is about 30 nA. 30 nA related to 2 mA is 15 ppm. Is it possible to measure the output current with 15 ppm accuracy? The are precision 6.5 or 7.5 digit DMMs that could do it, I suppose.
What do you think about this idea?

I've been accumulating tube amplifier parts for many years and decided now that I'm retired I'd spend a little time and put something together. I like the lower distortion and better load dynamic load handling of push pull triode outputs so I was designing for that. I had a pair of 6000 to 4/8/16 ohm transformers that had been removed form a 30W Sansui integrated amplifier. I don't recall the model number, I bought them many years ago from a person that was parting it out. I had a number of 6BG6 sweep tubes including several that were very well matched that I was planning to use as my outputs but I could only get about 10 watts RMS from them and that wasn't quite enough for the speakers I have. My goal was 15 to 20 watts even though I realize that's not much more than 10, it is enough to listen to the speakers in my work area without them clipping.

I experimented with a couple other tubes but then decided to try the 6AR6 triode strapped. I'd read about them many years ago but had never actually designed anything with them. They are pretty readily available and are an inexpensive alternative to most other power tubes. I looked at their tube data curves and looked like I'd need on the order of 450 volts on the plate and a -75V bias to get 20 watts RMS in class AB1 with my transformers. So working backwards I needed about 150 volts peak to peak from the drive stage. I'm fortunate to have collected many power transformers over the years and I had one that was rated at 380-0-380 at 350 mA. That allowed me to use solid state rectifiers for the driver and get a 550V DC supply to regualte down to 525 and also get 450 from a tube rectifier with a CLC filter. I've had good results with the 6SL7 long tailed pair with a constant current bias and using 525 volts and large value (220K or larger) plate resisotrs. I follow that with a 6SN7 cathode follower so the bias resistors don't load the 6SL7. The 6SL7 is capable of a very linear output over a large (nearly 300V) output. One gain stage wasn't quite enough so I fed the long tailed pair with a 6SF5 triode. I could have used many different parts there but since the other tubes were octals I went with the 6SF5. It's not used that frequently but it has a mu of 100 and is much less expensive than a 12AX7 or 12AT7 and it is an octal base tube.

The inductor in the CLC filter is a 5H 300 mA choke, way larger then what I needed, but again I had it and it does have the benefit of low series resistance. I've tried both the 5V4 and 5U4 rectifiers on this amplifier, the 5V4 gives a higher DC voltage by about 15 volts under full load. At some point I'll try a 5AR4, but I only have one of those so I wanted to make sure eveything works first.

I did some breadboarding first and then when I was reasoanbly happy with the results I put this together. The driver stag ahs a voltage gain of approximately 65dB and the entire amplifier has an open loop THD under 5%. Closed loop, I can get 20 watts RMS per channel with 0.05% THD at 1 KHz and 0.15% at 20 KHz. At 5 watts out the THD is well under .05%. I got tired of setting up meters to adjsut the bias so I used inexpensive digital voltmeters across 10 ohm cathode resistors to measure and set the bias. I can adjust the level and balance for the outputs. I'm currently running them at 32 mA, I started at 40 mA but there was no advantage to that higher current.

I included a top and bottom view. The fuse was not yet connected when I took the picture.

I enjoyed building this amplifier and welcome and questions and comments. If anyone is interested I'll post the schematic.

I spotted this new quad 32 bit ADC on the TI site, less than 2USD
https://www.ti.com/product/PCM1841-Q1?jktype=homepageproduct

The performance at both full scale and -60 dB is remarkable, not that long ago something like this would have cost a fortune

Does anyone have any experience with the Dayton Audio PT Mini-6? I'm trying to build a set of desktop speakers and my treble sounds a bit "splashy" compared to similar silk dome tweeters, almost as if it's lacking in clarity. Any suggestions?

Tip for relative beginners like myself, who specifically want to understand more about commonly used op-amp concepts such as noise, common mode, offset, etc. and want to simulate (LTSpice) and experiment with them. After a long search I found a suitable little book with a good explanation: "OP-Amps Circuits Simulations and Experiments" by Sid Antoch. For the chapters on filters and the like it is useful to pick up the basic concepts of complex arithmetic (brilliantly simple explanations in the excellent dsp_book_Ch30.pdf on analog.com) and the node voltage method.(khanacademy.org). Good LTSpice classes are easy to find on the Internet. More tips are very welcome.

Hi Everyone,

It's been a very long time since I sold all of my tools. I find myself now wanting to modify a pair of speakers to accept a plate amplifier. The speakers right now have a panel with speaker terminals which is a little small and will have to be enlarged, plus if possible I'd like to inset the plate so that it's flush with the back panel.

Is there an easy way to build a router template for a rectangular shape?

Thanks!

Erik

I have this vintage Audio Tekne power amp from Japan. There’s distortion in the left channel. Swapping tubes does not change anything. The distortion remains on the left channel.

This is fine. I’ve been told it’s likely a bad resistor. Seeing as how I have to take it to a local tech, I thought it may be a good opportunity to improve what I can while I have it with a tech.
First plan is to replace those sandcast resistors with mills resistors(or any recommended resistors of high quality) of higher ohm rating to lower bias and not run these NOS GE 6550 tubes so hard at 90mA even though I’ve read the GE 6550s can handle the high bias.

The point of the question. Does the capacitor on the tube socket make a difference in sound quality? I’ve seen Kondo builds where the electrolytic looks bypassed with a small film cap. Does that mean putting a film capacitor would yield sound changes/improvements easily heard?

Hello,

I posted a thread recently regarding a sealed 2-way all Dayton build (with 1" and 8" drivers) and I got a lot of help. Thanks a lot for that! As an alternative to that project, I started working on another sealed build with RST28F-4 and dual RS125P-8. It is for my 5.1 living room setup which has an 11" sealed sub. I would like to share with you some screenshots (crossover and full space response with diffraction) and it would be great to get your feedback knowing I am a beginner. My main questions are:

1- Is my design realist?
2- Do you see any flaws in the simulation?

Thanks in advance.

Hello im Barry. I have just bought a pair of tl speakers. The crossovers I need to figure out which wires correctly go to which driver. It's s design iv never seen before. Hopefully the pictures will help

Completed kit and sounding great! Kitted with sound-dampening material to almost eliminate microphonics. Includes power supply. $220 plus shipping.

Completed kit and sounding great! Includes power supply. $250 plus shipping.

I have two 1kW SMPS for sale:

Meanwell SE-1000-48 : $80 plus shipping
China MFG XKCL-1000-36 : $50 plus shipping

You can find info online and from the pics. These are perfect for e.g. TPA3255 amps, etc. Both are fan cooled. They are boxed in the MFG shipping packages, new and unused.

I will combine shipping if you buy both. Thanks for looking!

Last week a buddy lent me a SUT to try. I use a Denon DL103. Connected it to the Pearl. A lot of hum. Then proceeded to lower the gain in the Pearl by means of altering R14 if I recall correctly, less hum but still too much noise. The SUT had some input variables that I tried without a difference.
BTW, I could tell that there was no noticeable difference by using it.
My question is, out of curiosity, is the Pearl2 not compatible with a SUT?

How well would this dual voice coil sub work in a 1 CU FT sealed box driven by an Adcom GFA 545II with one channel per voice coil?

https://www.parts-express.com/Dayto...ce-Series-HO-DVC-Subwoofer-295-463?quantity=1

An Adcom GFA 535II will drive a pair of Klipsch bookshelf speakers.

A Kicker KX2 active crossover is used for the high pass and low pass.

Used to be active here over a decade back. Starting to pull some of my old stuff out of storage and complete some projects I started a LONG time ago. Have to finish my old Leach Amp and Alpeh-X

Can anyone tell me the 3 LEDs in the front and what they are/colors each one is? I broke them off trying to remove the PCB when it got hung on that weird light chute thing.

I came across a OTL amp using a parallel string of 6AS7 or 6080 on the top and a huge inductor on the bottom. I can't find the Japanese article again. I did come across a simpler and abbreviate schematic dated 1952, see attached, but it wasn't the same circuit. Is anyone familiar with such a circuit?
I built the P. Dickie Jr & A. Macovski (June 1954) circuit but increased the output to 9 parallel per channel to handle 8 ohms speakers which I thought might be reconfigured to the SE design if I can find it.


p

The air pressure between Leadville and New York City can vary by a lot. Does it affect loudspeakers? It should but by how much?

Hi guys,
I've got a mackie thump15 powered speaker in for repairs. The issue was the sound cuts out when the speaker is turned up loud. My initial thought was dry joints and intermittent connection due to vibration.
When I got it in and after removing the amp I measured the resistance of the drivers and the woofer measures at 1.7ohm!. That didn't look right. The marking on the speaker states that its suppose to be 8 ohms. So then my thought was the speaker coil have shorted partly and the amplifier chip was detecting a fault when driven hard and was cutting out. The amplifier chip used is TDA8924TH.
But here is where things got a bit interesting. To check whether the amplifier was functioning I connected my test woofer rated at 8 ohms and it was working fine no issues (my test woofer was not attached to the enclosure). To see whether the sound cuts out, I then checked with the faulty woofer and it worked perfectly fine :S and same as before the woofer is not attached to the enclosure.
I haven't got a working mackie thump to measure the actual resistance of the coil of the woofer. The label on the speaker says 8 ohms though I know sometimes labels can be misleading. If some one can confirm the resistance of these would be greatly appreciated. Can the TDA8924TH be paired with a 2 Ohm-ish load and work?
Thanks in advance for your input.
P.S- I don't hear any coil rubbing when driven with signal or pushed and pulled by hand

This seems to be a common design issue with many HK units, including this one.
There are a few switches that tick or pop when used. Sometimes more than other times.

I get a big pop when using the tone defeat switch, but only if I just turned the unit on.
There is usually a tick when switching to AM.
There is a tick when using the treble cut switch.

Are there any tweaks I can do to prevent this? I've tried reducing some of the signal path capacitor values, HK seems to like making their cutoff frequencies crazy low.

Power amp input capacitor was changed to 4.7uF.

And in the preamp, I tried changing C6/C33 to 4.7uf (from 47). And then C13/C40 to 4.7 from 100uF. Both are highpass filters with a 100k resistor. This should give a cutoff frequency of 0.34Hz, right?

Service manual is attached, preamp is on page 17. Does anyone see any glaring issues?

Hello,

I need your knowledge about a rega Elex mk1, PCB V2.

First of all, does anyone have a service manual for this amplifier? It's crazy, on the PCB many components have the same marking!

The amplifier worked for a short time with one channel less efficient than the other. It ended up blowing the right channel output transistors.

Someone has obviously already worked on this side of the amplifier. Some transistors have been replaced as well as diodes and resistors.

Do you know if this amp accepts being powered on without the C2837 and A1186 output transistors so that I can check if something else has failed?
Before breakdown, the power transistors were powered and +-43V and the level difference problem seemed to come from the power part of the channel in question.

Thank you in advance for your help !

Edit : surprisingly, an LED of the phono part of the same channel is also HS

Hi to all
I've been trying to repair this excellent CD player for a few days now, with no success. It reads disks only occasionally. The disc is loaded normally and starts spinning "crazy", but the laser head remains stationary at the starting point (doesn't slide at all) and of course, there is no RF signal output. However, the laser head moves up and down trying to focus every time the "PLAY" is pressed, but I couldn't detect if the laser beam is active. I did a thorough cleaning of the lens of course. I then tried to check the laser beam with my smartphone camera placed over the lens and could only see a small and very weak red dot. I checked all voltages and they look OK. The voltage across the "LD" laser diode (pins 7 and 11 of pickup assy flex ribbon, see on the left side of attached picture) is close to 1.9 volts. The spindle motor is working, the same applies to the carriage motor. Do you think the laser diode is deficient? Attached is the circuit of the PEA1343 pickup.

We have a big Lundahl Transformers sale going on, 20% off list price, for larger quantities, additional discounts will apply.
For all the details and pricing, please go here, https://www.erhard-audio.com/Transformer-Sale.html

Hello Jan-Peter, Bruno,

As this subject maybe of interest to more readers, just a few questions here on the Hypex UCD180 modules.

I received 4 UCD180 modules today. Apparently I`m one of the first customers since I had serial number 0004 to 0007 🙂
I have not yet hooked them up to a power supply, so I have not done any listening tests (will have to wait until weekend or even later).

A few questions concerning the input of the module. The module has a symmetric input using a NE5532 dual opamp. It seems to be used as an instrumental amplifier like input with the UCD itself acting as the 3rd differential amp. I can not see all traces on the PCB but it seems to be connected like an instrumental amplifier with a gain of about 4.5 or so. The outputs of the two opamps go to the inputs of the UCD amp itself. This is done by two coupling capacitors that are 22uF electrolitic capacitors. Assuming that the input impedance of the UCD amp itself is something like 1.8k for the inverting input (as stated in the classd.pdf file), then that gives a high pass filter at 4Hz. That should be fine for all apllications. However, when I`m going to use this amp for a tweeter or a midrange, I sure would want to replace the electrolitic caps with a different type of cap and of course with a lower value. Are those caps really required? What happens if they are replaced with a piece of wire (0 Ohm resistor). Would that give problems when the input voltage is not purely symmetrical? I assume that when the input signal is pure symmetrical, it sould not hurt to remove the caps, would it?

Best regards

Gertjan