Hi All. These, and other models from EBay vendor HKAUDIO9 keep coming up on my email notifications. They are reasonably priced, but I can not find any information or reviews on them. Has anyone tried them out? Here is the link....
5K SE UL C-CORE AUDIO OUTPUT TRANSFORMERS (pair) FOR ,KT-88, EL-34 | eBay

I built up a PC USB DCC controller pcb for model trains.
I sent a signal from the pc to start the train and it set off, then it started stopping and starting all on its own !
Then over load LED started flashing randomly.

I unplugged it and did a visual inspection.
Then spotted R1 missing which is the master clear pull up resistor for the PIC microcontroller.

I just finished drawing up the plans for what would be my flagship, had I the funds to build it. I will be built though. This design uses 8 of the 1" Tang Band W1-1070SE drivers in a wooden Unity horn like configuration plus a giant fiberglass spiral rear horn. Frequency response is ruler flat down to 45 hz or so and hits 125db down to that frequency (corner loaded). The impulse is fantastic and group delay is comparatively moderate (averaging between 8ms and 15ms with a peak of 35ms at about 50hz. This design is so efficeint it could reach it's full potential with a very low powered amp(2-3 watts). I'm dreaming of the Trancendant Sound OPT SET.

Here is a link to the Sketchup Model: http://sketchup.google.com/3dwarehouse/details?mid=a9c506f7521e56cde1fe2e95a7b336e7&prevstart=0

This amp has the red board with the date of 2005.

Amp is stuck in protection mode all of the outputs test good .

TL494

Pin 1:0.00
Pin 2:4.96
Pin 3:0.05
Pin 4:0.00
Pin 5:1.47
Pin 6:3.65
Pin 7:0.00
Pin 8:0.61
Pin 9:0.03
Pin 10:0.04
Pin 11:0.63
Pin 12:13.65
Pin 13:4.96
Pin 14:4.96
Pin 15:4.96
Pin 16:0.00

I hope it is not a problem to also make new thread about my problem with 1212m. So here is post again:

Hello,
I have 1212m rev 1 with FW port.
Looks like nice sounding card.
Anyway, in the last time, i have problem with one channel.
I'm using the cards analog outputs, unbalanced, and connected to the int amp CD input.
Anyway, problem is that the left channel has become obviously quieter than the right channel! Id say about 20db quieter. What can be the problem, please?
I experimented a little, and found out that when I take left TS connector and pull it about 1/2 inch out of the card, the sound becomes OK level. So, i would say that when using left TS the sound is attenuated about 20db but if using RS the sound is OK. On the right channel, the sound is the same level if the connector is fully put into the card (TS) as it is if I pull out connector about 1/2inch so it uses RS signal. I hope to help you with this to help me find a problem.
Also, I measured voltage on the outputs: right TS and RS have about 0mV while left RS have also 0mV but left TS have about 20mV.
Please, thanks for help.

I'm doing a little project intended mostly to utilise the parts I have in my drawer. It is a fully differential PP amp with the phase-splitting input transformer. And I need the volume control for it.

The most sane way is obviously to use the dual pot after the transformer, one gang for each secondary half. The problem is this is stereo amp, so I'll need the quad pot - and I don't have one of the appropriate value at hand.

I do have a selection of dual pots though, so I'd like to have a solution that uses one gang per channel. Two options come to mind - installing the pot before the transformer as the usual attenuator, or using the shunt configuration (with two constant resistors) at the secondary side. Unfortunately, both those methods make for source or load impedance varying with volume, and transformers don't really like that.

I came up with another method that seems pretty obvious to me (schematics attached), but somehow I haven't found anyone using it, apart from somewhat similar idea from the Sowter 9335 application notes (example #2) which uses multitapped secondary itself instead of the pot.

Are there some potential issues with my idea I'm unaware of? Dissimilar output impedances, unexpected phase shifts, stuff like that?

Thanks in advance!

Well, if you dont like sand in your tube projects, and you need a 555 timer... Just use this one made out of 18 tubes!

Building the Largest 555 Timer in the World out of Vacuum Tubes - YouTube

Honestly, I was not able to find a suitable forum for posting this question. Please direct me if this is inappropriate.


I am planning on building an active 4th order LR filter for my 2.1 subwoofer system. LR filters have a -6 dB point at the crossover frequency.



Adding the voltage at this point exactly produces 0 dB. -6dB corresponds with half the voltage at each output.


But the the power at each amplifier output is proportional to the square of the voltage, so a quarter of the power. Sum that and I get half the power.


So to me it seems that the voltage is constant. But the power has a -3dB dip at the crossover frequency.


Since LR-4 is quite popular and applied by many audio systems I think I make a mistake in thinking. Where?

I have a Philips CD880 that I bought new in 1989. I decided to open it up to check for signs of leaky caps. There is one that has yellowish-brown gunk on the PCB around the entire base. It is an Elna 3300uf 35v with a red case and gold print but no series marked on it.

I have searched all the usual Elna dealer sites and Ebay with no success. For some reason I can find almost any other size except this one which shows as being made in the Elna RFO, R2O, RA2 and RA3 series. Does anyone know of a source?

I have too many dacs so I sell boards for Buffalo iiise Pro ES9038 dac from Twisted Pear Audio. For sale:

Buffalo-IIIsePro38 2-Channel DAC w/Full Series Regulator Set
(1) Buffalo-IIIsePro38 2-Channel DAC Module (Assembled and Tested)
(1) AVCC-SR Dual 3.6V Series Regulator Module (Assembled and Tested)
(2) TridentSR 3.3V Series Regulator Module (Assembled and Tested)
(1) TridentSR 1.3V Series Regulator Module (Assembled and Tested)


(1) Centaur 2A Power Supply Complete Kit (Assembled and Tested)
(1) Mercury Balanced I/V Stage v1.1 Kit (Assembled and Tested)


To complete the kit you will need a PSU for the Mercury I/V stage like the Placid HD BP Power Supply Kit, and two transformers (9V+9V 30VA and 15V+15V 50VA).


Price: xxx Euro, including shipping within EU (outside EU please ask for quote).
PayPal friends and family.


The Buffalo-IIIse Pro (Stereo Edition) 2-Channel DAC


Thank you for watching.


Sold

I`m thinking to change it in my sony str-k7000 to muses02, any opinion about?

thanks for all


Sony STR-K7000, Service Manual, Repair Schematics

.

I have a couple of Holden And Fisher 800va 120v primary and 80 volt CT and 60 Volt CT secondaries are these any good ? What would these be worth ? I pulled them out of a pair or SIA power amps which were made here in Toronto. Peter

Hi,

Have just recapped my owned-from-new NAD 3020A.

Sounds good on first outing and have managed to get 0mV DC on the speaker posts.
Attaching some photos.

Prior to buttoning it up, please could anyone knowledgeable on the recapping of this particular amp let me know if I’ve made any obvious mistakes or omissions?
I used Nichicon UKL in the audio signal path (hope I got the correct locations…), UPW elsewhere, except 4 UKW 33000uF for the power supply.
A sprinkling of Wima caps.
(Have to say that most of the pulled caps gave reasonably good readings on a cheap transistor tester.)

Many thanks all.

Greetings,


I repaired a T753 just a few weeks ago (broken voltage regulator) and I started sending IR signals to the T753 using an arduino (I am not willing yet to buy an expensive original remote, especially not taking into account what is about to come).



At first it was easy and it worked fine. After a few minutes however, it started taking many clicks to make it do what I wanted it to do. After a day, I tried again and then it didn't work at all anymore.



Of course I sought for the problem in my improvised remote, but when looking at the IR LED with a camera and testing it on another device, I concluded that it was working perfectly.


The built-in screen was behaving weird after I repaired it too; i.e. it randomly shut down and when poking the power supply cable it worked again. Of course I removed the supply cable and tested it, but I wasn't able to find the problem. I tried testing the connectors, but there was nothing either. I don't think this is connected though and it has worked ever since, so I don't think this problem is that important.



I searched on the internet and found that other people had similar problems (not both at the same time) but weren't able to fix it. I sent a polite email to NAD to ask if they had any information about it, but they just plain ignored it. I guess it's true what they say about NAD being bad at customer service and this is discontinued for many years now too, so I didn't really expect anything.


However, I really like the sound from this amplifier and without IR, I can't do settings regarding my setup and that renders it almost useless for surround. If anyone has bumped into the same problem I would like to know about it and if anyone has fixed this issue of course.

For sale is a Dayton EMM-6 measurement microphone in great condition. Includes case, wind muffler and mic clip.

This is a great mic for taking measurements for speaker design, room EQ or any other audio analysis purpose. It is a surprisingly flat response microphone to 20kHz even without any calibration file. However, I wouldn't trust the supplied Dayton calibration at all, it's far too "noisy". I will provide the Dayton calibration file, but will also supply you with 2 alternative calibration options. One was made using a Dayton Omnimic as reference, and the other was made using a Line Audio OM1 as reference. Both are within about 0.5dB with the Omnimic cal providing a slight lift (0.5dB) in the upper mid / lower treble range, so you can decide which is more "correct". Because the mic is so flat as-is, the calibration is only providing about +/- 1dB of compensation, so the differences between them are fairly small overall.

Asking CAD$40. Expect shipping cost around $20 via Canada Post. It probably doesn't make sense to ship a low cost item like this internationally.

Hello,

i am interesset in an amp with the 100TL tube.
I can't finde any schematic about that. Can anybody help me?

Greedings from Germany
Jürgen

I have 2 ATC SM75-150S and 4 TAD TL-1601a. I run a studio and was wondering whether to build my own speaker with these drivers or sell the drivers and buy some Genelec 8351s which Ive had my eye on and would integrate well with surround sound glm Genelec system.
If I was to build I have some questions :

1. How hard would the build be for a beginner? I have advanced sound engineering skills ( I have ran a studio for over 20 years and can do things like pseudo anechoic measurements etc) and rudimentary carpentry skills but never built a speaker.
2. Are there any designs for the cabs for a project like this? (I would love to stick them in a tree trunk - bad idea ?)
3. What tweeters would be good with these (budget if poss)
4. Is there a ready-made crossover available for these?
5. What amplifications is going to be needed? I am not into snake-oil - I just want an amp that will do the job

tx

I was going to make my own speakers -

ATC SM75-150S and TAD TL-1601a

but I've decided that it's probably going to be too much for me at the moment and I want some other equipment so they're up for grabs make me an offer - buyer pays postage and any PayPal fees if we do it through paypal so factor that into your offer. Im based in Ireland.
All drivers are working well - I have tested them with REW, and a measurement mic in pseudo anechoic conditions. If anyone interested in these I will retake the measurements and send you the MDAT files so you can check everything is performing to spec. From a studio in Dublin that closed and used occasionally to show off to clients. One ATC driver has a chip on the plastic surround (see photo) but it does not affect performance according to my measurements. One dustcap in one of the tads is dented - again I noticed no performance difference.
Images can be found here :

IMG-20210326-120936 — ImgBB
IMG-20210326-125229 — ImgBB
IMG-20210326-125243 — ImgBB
IMG-20210326-125253 — ImgBB
IMG-20210326-120946 — ImgBB
IMG-20210326-120959 — ImgBB
https://ibb.co/tJdG5f9
https://ibb.co/W60v4c2
https://ibb.co/qdVpCQM
https://ibb.co/SP4skD8
https://ibb.co/K985LRm
https://ibb.co/QCK7nxz
https://ibb.co/G9PDFyf
https://ibb.co/DGNnvJd

Contact : augustineleudar@gmail.com

Hi,

I own an Arcam FMJ P7 Amplifier (7x150W/8) and was wondering how I would go about adding a Mundorf Silver/Oil cap to the RCA input,

I've seen number of DIY amps add a 3.9uF cap to the RCA input.

I've spoken to a couple of DIYers and they said anything higher then 2.2uF will do the job, how do I work out the right uF? or do I just try and see?

How is it connected? Just to the positive input? or is it the negative?

Can someone provide a quick comparison, pros and cons between the CDSP6x8 and the 4x10HD.

Application will be a 4 way stereo hifi speaker crossover with twin woofers plus mid and tweeter. Ideally I would use the output channels for crossover and to remove peaks/dips to get a 30hz to 20khz flat response (anachoic) and then use the input channels to tailor sound to room/taste. Source will be either Chromecast audio direct into digital input or via an Audio GD DAC into an analogue input.

All comments welcome on these or alternative minidsp products. Thanks in advance.

i just found a dream amp NIB/NOS, a Meridan 551. It's the amp that got me into the hobby during a dealer demo 25 years ago. If NIB is to be believed, should I be concerned with it's electrolytics? The amp could be up to 30 years old with un-used caps.

Conversion using UF5407 800V 3Amp 2-Pin DO-2 Soft Recovery Ultrafast Plastic Rectifier Diodes in a standard octal plug with the cap off of a fabric conditioner bottle a perfect press fit to finish it off 😀

Hi I have a Cambridge Audio Azure r551. Had it five years and been great amp . Suddenly it's started making my speakers crackle for five mins or so the diminished to nothing noise not sound. If I don't turn amp off its fine. But every time I turn on I get this problem. I want to sell it to buy a Cyrus One hd .

Any ideas guys

Magnequst BH-5 Output Transformers 3k primary SE parafeed 9ohms or 16ohms Nickel stripe.A Pair Price $400.00 USD Plus Shipping
Good choice for a 2A3 or 300B tube.(Sold)

Hi all,

I recently bought a really rare Sony 702ES DAC (from 1983 - one of the world's first outboard DACs!) which has a problem - the right channel has no audio at all. The left channel works but you get a bit of static in the sound when it's cold.

I'm no electronics expert but I've had the lid off and done a visual check and everything looks okay. I notice that one of the two DAC chips gets really hot but the other one doesn't.

Apparently this is very similar to the 703ES DAC.

Anyone got any ideas of where I could start?

Thank you.

Hi
I have a wooden floor that is on top of a concrete floor.

As far as I have read then spikes is good on at "sensitive" wooden floor and decoupling is good on a concreate floor.
But my floor is kind of a bit of both, so should I couple or decoupling?

I want to tighten up the bass if possible.

Today the speaker is sitting directly on the floor.
I intent to diy whatever it is I need - just at bit unsure of what it is I need 🙂
My own guess is decoupling, but please let me know what to do 🙂

This list is made from my few years of experience

Lower value is minimum power required for proper working
Maximum value is power of new or excellent condition

VAM 1202 300 to 500uW
TAOHS-HG1 300 to 500uW
OPH-32 200 to 320uW
KSS-121 (BU-1) 210 to 240uW
KSS-121B 210 to 240uW
KSS-123 300 to 400uW
KSS-100A 250 to 400uW
KSS-151A 105 to 120uW
KSS-190 85 to 115uW
KSS-240 original 110 to 130uW
KSS-240 modern replacement 50 to 60 uW
KSS-210 modern replacement 40 to 50 uW
KSS-210 originnal 100 to 120uW
KSS-150 100 to 120uW
KSS-152A 120 to 150uW
KSS-271A 95 to 110uW
KSS-272A 90 to 105uW
KSS-270A 105 to 125uW

all measurments were made using Hioki 3664 meter

Hi.

My google-fu is weak today: I cannot find any description on what kind of tube is sometimes used for extra insulation on SMPS transformer windings.

I´m guessing is high-temp resistant, and guessing HPFE?
Its often clear, but I've also seen red.

I tried to show the typical example in the picture. Highlight with RED.

Any ideas?

Kind regards Troels

Cheers, deathmetalmusician in Eigenstate Zero and hifi-interested geezer. Buying old stuff and trying to make it shine. Very new to the diy-thing as far as hifi goes. Got some questions as it were. Cheers!

Working on a satellite receiver that won't power on. Only suspicious looking part of board is in PS section. Attached picture; does discolouration look like a failure or just heat discolouration?

Hello, I had 6N6P resistor loaded in my decware Zen clone.
It sounds pretty good, dark background, very smooth.
Then I rewired the filaments and tried E80CC - this was brutal improvement. Hard to describe but simply more musical, I cant forget the sound of this tube.
(both tubes something like 290V B+, unbypassed cathode resistor 430 ohms and plate resistor of 20Kohms).

So I became curious. E80CC are expensive so what about to try the ECC99? How it sounds?
Thank very much for answer.

Does any one have a copy of the parts list for this design (as published in old copies of the maplin catalogue and used in their diy disco consule many years ago). I have a schematic and a number of broken modules. Any help welcomed

Boston ac. Hps 10ho panel no power supply, need transformer values!

I have a Boston acoustics hps 10ho panel I bought from eBay to power a 10" sub from an old amp/sub combo. Panel looks great and will power my sub but it didn't come with a power transformer and that model is discontinued! No love from Boston. I have schematic diagrams and enough equipment/ knowledge to wire it in, but am I hooped to find the specific voltages needed? I will try and attach the PDF of the wiring.

Hi,

Believe it or not, at this point in my life completing a large class A project is something I don't have enough time for. As time goes on, and I sit and listen to how badly my present tube amp drives my 88db speakers, and dream of owning a big fat class A.

I certainly look forward to having the time to sit down and construct my own 'baby', but it's not going to happen any time soon! 🙁

In the meantime, an opportunity to purchase a second hand Plinius SA-250 has come my way, obviously for a second hand price.

I was wondering if any of you had any experience or comments in regards to plinius or this amp. From the reviews I've read it sounds like it could be a good building block for my 'reference' system.

Any feedback welcome!

<a href="http://www.pliniusaudio.com/pro/pro01.htm">Product Information from the Plinius site</a>

<center>
<img src="http://www.pliniusaudio.com/secimages/photos/sa250s_lg.jpg">
<p>
<img src="http://www.pliniusaudio.com/secimages/photos/sa250in01_lg.jpg">
<p>
<img src="http://www.pliniusaudio.com/secimages/photos/sa250in02_lg.jpg">
</center>

Jason.

Hi! I’m fairly new to diy audio and new to this forum. I got a pair of diy speakers from my brother for free but one of the fostex fe167e drivers is damaged, as in no mid or bass. I’m not sure what the cabinet design is specifically, but from what I have gathered based on taking out the drivers, it seems to be a mass loaded transmission line, as in this website Fostex FX120 DIY ML-TQWT (Transmission Line) Speaker Project. Is there a current fostex offering or anything that I could get my hands on for fairly cheap in the US market? Thanks!

Recently, I accidentally touched the resistors on legato and got burnt. I measure the temperature and surprising me that its over 75 deg C. Further measure those underneath the BIII, they are over 80 deg C. Is it normal? Such heat may damage or shorten the BIII life.

If you have the measurements for a horn, how do you calculate distance between each segment when the horn is “unrolled” onto a flat sheet. In the constructed horn the length between each section will be the same, but when the pieces are flat, the length will get longer as it gets closer to the mouth.

I am building an altec 1505 out of 1/8” plywood, if that is relevant!

Hi !
I was looking for schematic Tube 211 SE with EL34 driver but not found.
Anyone please help me

LM1875

Hello everyone, I'm new to the forum and I wanted to ask you for a courtesy given your experience,
could you give me a correct schematic for an amplifier with lm1875,
I'm not very experienced, but I'm trying to make one.
I followed some pattern found on the net and they don't seem to work.
I tried to find some in the forum but I couldn't.
every time I assemble one I have a problem lately
the volume was faint, in another loud noise from the speakers.
I just can't understand where I'm wrong, but I would like to start at least from a fixed point, that is a working and well tested scheme.

thank you for your kindness.
See you soon

ps this is the last pattern I followed

Tales From the Chip: LM1875 Audio Amplifier : 8 Steps (with Pictures) - Instructables...
?

I made a PCB to hold 2 diodes, a cap and a bleeder resistor for use with a center-tapped transformer.

Upon initial test, fuses are blown.
Increasing the fuse size causes a momentary buzz from the transformer and then blown too.

If I disconnect the transformer leads from the PCB, the transformer is outputting 600 VCT so it seems to be fine.
It seems like there is an obvious mistake here that I'm overlooking.

The 600VCT wire leads are connected to pin 1 and 3 on the input, and the center-tap lead is connected to 0V output.

The parts I used were:
2x MUR460 diodes
150K 2W bleeder resistor
220uF 450V snap-in capacitor.

Thoughts?

Im working on a PPI Art A600 which had failed outputs on the left channel. I replaced all outputs in BOTH channels with 2n6488 and 2n6491 as the originals were BDT81/BDT82 and NLA. There is 1 twist as there is an extra 91 on one channel, and an extra 88 in the other channel. I believe I did this correctly as I went over it 3 times before soldering. I did not replace any drivers which are C2344 and A1011 being controlled by MPSA06. All these transistors are testing out well off the PCB.

The amp powers, and gently plays through speaker terminals to my HoneyTone, but as soon as I hook up an actual 4-ohm load the amp clamps on my power supply and there is no sound.

Another symptom is the amp can only be powered for about 40 seconds before the outputs get too warm for idling. Also amperage draw starts at 1.3A, and over that 40 seconds rises to un-expected levels. I pulled power at 2.75A as it was starting to really take off.

All VR pots are set to full CCW. There is no voltage across several emitters I've tested.

The left channel has 1.4vDC on it while the right has +-0.1vDC. Theres a DC reference pot but it can only get the left channel down to about 1.1vDC.

Am I missing something? I checked multiple components and nothing is popping out at me.

Hi all,
I really appreciate any of you who can help me find schematic diagram of my OLD Girl who stop working just recently MERIDIAN 557 Power amplifier, this old girl serve me very well for the last 10years, lots of parts are toasted, especially in HVtransistors, so please if anyone of you have come across or may have repaired same issues that I have please share it with me thank you all folks

Hello all, Just joined this site. Seems pretty legit at first glance. Surprised I haven't seen it sooner than now. Anyway, looking for anybody that can help with some repair questions on a Rockford Fosgate 600a4 mobile audio amplifier. When I purchased this amplifier ($20) I did not do any inspection of the unit and was unable to test. Oh well,m I'm the guy that enjoys the vhallenge of fixing things!!! In the event that it didn't work. Well, it worked great! But....,you knew this was coming, the gains were so terribly gouged out that they were hardly recognizable as potentiometers. I tried soldering in a set from a different amplifier ( Not RF ) and now it does not produce any sound at all. Looking for the how to and know how to figure out my issue! Any help is appreciated.

Hello guys looking for MM tube phono stage can be diy or brand for max 300 EUR.
I am located in the EU so if someone has something interesting for sale let me know.

Thanks!

Last fall I acquired around 4000 records from an audiophile friend who is moving in retirement. I have gone through them and kept what I can manage to store and am now looking to move the remaining collection on to the next person who will appreciate them. I did not cherry pick for value. I used a somewhat random criteria as there are far more records here than I wanted to keep. The collection is mostly Mozart, Beethoven, Bach, Brahms, Chopin, Handel, Litzt.

Most of them are in reasonably good condition and are very listenable. I figure there are about 1600 records here. Disclaimer, As one would expect, there are definitely some things that nobody is likely to want. You will absolutely have a junk pile of records that you just don't want.

Make an offer.

I know what they are worth (or not worth in this case). I am most interested in them not ending up in a landfill. I want them all to go, not sell one or two here or there.

Located in Vermont.

I have some ST102-267 Cores that I want to use to make some simple low power Push-Pull SMPS transformers. The input is 12V the output will be connected to a diode bridge to give +/- 30. I have finished the control circuitry and the MOSFET's, everything is running @ 45Khz. Now my question what is the best method to wind them? I need 12 total turns in the primary.

Would I:

A) wind 6 turns (around half the core) center tap then wind the next 6 turns in the same directions back to the beginning of the core?

B) Wind 2 parallel wires 6 turns each all the way around the core then connect the output of one into the input of the other (at this point also connect the input power)?

As for the secondary I know I should wind the secondary in the opposite direction of the primary but should they be wound all the way around the core or only half CT then the other half also?

The transformer will be connect as seen below, disregard the rest of the schematic as the controll side is totally different.

Good evening altogether,

I am looking for a DIY preamp to go with a pair of Troels Gravesen Ekta 2D. Goal is to add some of the tube warmth, sweetness, musicality (you know what I mean).

Might the Elekit TU8500 do the trick here? Any suggestions?


I hope that this solution will give a powerful, sweet, warm, detailled and balanced sound whilst making sure the electricity bill and room temp stay down. Do you agree/disagree? Any thoughts?



Best Regards from Vienna,

Johannes

Hi , someone have mid-high Front loaded wood horn Plans ?

DWG or some other format for CNC.

I'm trying to decide between the Fountek Neox1.0 and the Fountek NeoCD3.0. Is there a big difference in sound between these two tweeters? They are roughly the same price right now.

Are there diy amp projects and commercial amplifier products, where the AD-846AN serves as front end?
Thanks for advices.

Harman's Real-Time Linear Smoothing/RLS for DAC (HD7725/HD-7725) still in use on currently available Audio Components ?

While cleaning up I discovered the description of this (at those days) new technology in DAC's as a copy from the German magazine "Infosat", issue 60 published in March 1993 - see attached files.
Please note, the last both images shows the cover of this magazine as an example, bot not from issue 60.

Are there DA-converters from currently production, where this feature is integrated or is this technology vintage stuff resp. outdated technology ?

Thanks for advices.

Hi Admins

May I suggest we create a new sub-forum, under “Design & Build” specifically catering to modern building technologies: “Laser, CNC & 3D Printing”?

Within the current forum structure, it’s not a simple matter to find posts relevant to these topics.

For your consideration.


Thank you

Hi all, I am building a new input switching board for my DIY amp (using a couple of CMOS and relays). I made it so that I could connect each input direct or through a voltage divider. The idea was to use it as a passive attenuator for sources too hot. The input board is going to be connected to a DSP (ADAU1701 based) with an input sensitivity of 1.0 Vrms and an input impedance of 10k. My RIAA preamp is usually outputting around 0.5 to 0.8 Vrms but my CD player and DAC are too hot at around 2.1 Vrms. So I am seeking the preferred resistor values if I would run the CD player and DAC through voltage dividers to add some -10 dB attenuation.

The values I am considering are (given R1 in series and R2 parallel to ground):

Alternative 1: R1 = 5.6k, R2 = 2.7k => -9.75 dB, Zin = 8.3k, Zout = 1.8k
Alternative 2: R1 = 6.8k, R2 = 3.3k => -9.72 dB, Zin = 10.1k, Zout = 2.2k

The DAC got a quite high output impedance of 480R so I guess alternative 2 might be preferable based on Zin but I guess it has to be balanced against the Zout. So my questions to you all, did I get the math right? Would you go with alternative 1 or 2? Does it really matter? Any other suggestions or comments?

One reason I am questioning my values is the following Goldpoint page: Balancing Amplifiers

According to the tables on that page for an amp with 10k input impedance they recommend: R1 = 19.1k, R2 = 75k. For those values my calculations gives => -1.97dB, Zin = 94.1k, Zout = 15.2k. So what am I missing here?

Hi,

I built 2 hypex UcD400HG w/HxR monoblocks about 4 or 5 years ago.
At that point the switch mode PSU had not been introduced, so I used 2 500VA toroids.

I think this amplifier sounds amazing for my studio monitors, and have decided that I must have one in the living room as well.

Since then, the price has gone down by about 30-40%, and the nCore has been introduced as the new "top of the line". The nCore costs just slightly more than the UcD400HG used to.

The specs speak for themselves, but how does this translate into practical terms? I currently own the following relevant speakers: ProAc studio 100 (for mixing), PMC LB1 (for mastering) and 90s Seas Argon (large, full-range, very enjoyable and fairly inexpensive, for the living room)

For loudspeakers at this level, will I even notice the difference between the two amplifiers?

Class A or not, is there anything else in the price range that is regarded superior to the Hypex?

Looking for output transformer for Silvertone DGR 9012 amo, model 1471. Any equivalent trans will do.

The Suez Canal has been blocked and a big backlog of ships is building up after a huge container ship ran aground during bad weather.

I'm sure we all are here a bit of experienced sailors now and we can discuss this situation.

SOLD: 2SJ109 + 2SK389 (Genuine, NOS)

SOLD

Update: all JFETs are gone.
---
Genuine Toshiba 2SK389s (NOS) purchased many years ago in Sweden before the world turned bad.

10 pcs. 2SK389GR left, all same date code "2K":

IDSS-measurement (DGS1/DGS2):
1. 3.5/3.5mA
2. 3.1/3.1
3. 5.9/5.9
4. 4.5/4.5
5. 3.5/3.5
6. 5.1/5.1
7. 3.4/3.5
8. 4.1/4.1
9. 3.2/3.2
10. 3.4/3.4

Hello all,

I have a Buffalo III SE (non-pro, 9018) and am wanting to hook up an I2S source for my digital (well, non-silver disc digital) content.

The most obvious solution to me was a raspberry pi 4, but after some searching here it looks like everyone is using BeagleBone Black boards.

I know I'm late to the game, but why is this the case (BBB over rpi)?

Would BBB still be the recommended I2S source (Quboz streaming, NAS storage, etc) in 2021? Isn't there a lot more app support for rpi?

Also, what is the advantage/necessity of using the various reclocker boards vs I2S directly from the pi (or similar)? Doesn't the 9018 already do reclocking to be asynchronous? Sorry if I'm missing something, I don't know what I don't know

Thank you!

Tuning a Bass-Reflex enclosure with a impedance curve

I recall back in an earlier day reading a Popular Electronics periodical about early base-reflex enclosures. The article published the impedance curve of a speaker in a sealed enclosure. Then the author began drilling a number of half inch holes in the enclosure. With each added hole the original impedance peak lowered in amplitude and increased in frequency. Also with the addition of new ½ inch holes there was a new lower frequency peak added to the impedance plot. With the addition of additional holes both impedance peaks increased in frequency. The lower frequency peak increased in amplitude and frequency. The higher impedance peak continued to reduce in amplitude and increase in frequency with addition holes in the enclosure.

This past Friday I took out a base-reflex enclosure, about 1.5 cubic feet with a JBL 2204H driver installed. The enclosure has a fair amount of polyester fill and two 1-3/4” holes drilled through the 3/4” front baffle. I plugged the holes and plotted the impedance. Then I unplugged one of the holes and appended the plot, then unplugged the second hole and appended the plot again. The AP plot is attached.

It looks like the enclosure could use one more 1-3/4” port to make the impedance peaks close to equal.

Thoughts

Thanks DT

D

Totem element ember -question for owners

I have a question to all Ember owners. Can you tell me the diameter and length of the port in your embers ? Thank you Peter

Hi all, new to the forum... Not an extreme 'audiophile' or anything. But I do love music and have assembled two elekit amps and one preamp.

I have a TU-8200 w/ an 8500 preamp on JBL 4312M II compact monitors and a TU-8600 on Klipsch Heresy IV speakers and for input, a Technics SL-1200MK3D turntable...and an iPhone. Love all the amps, and am really pleased with the new 8600 in general.

I have noticed one issue though, the turntable sounds great running through the 8200 even without a preamp, but pretty ... not as great ... running through the 8600 with no preamp.

I want to learn a little more about the technical side and was wondering if anyone could provide an explanation as to why that may be so. On the practical side, the 8500 doesn't match the 8600 aesthetically so I don't want it sitting next to it on the shelf!


I won't rule out anything I may have screwed up on the build, but I'm inclined to think it's not an issue there. And it doesn't sound terrible or anything, just weak in comparison to a computer or phone input, which is the opposite of my other elekit set up.

Hello,

Does anyone have a source for legitimate BC550/BC560 transistors?

BC550 can still be purchased, but BC560 seem to be gone from "normal" channels (i.e. Digikey, Mouser, etc.).

Anyone had any luck with Ebay or Aliexpress? Care to list any specific sellers?

What about CDIL (Continental Device India Ltd) version of the BC550/BC560 that is available via TME (Transfer Multisort Elektronik)?



Thank you,

David.

Hi, can i use 1.5ohm resistor instead of 1ohm for lm1875 amplifier? I know that the value of this resistor isn't critical but still... has anyone had any experience in this regard? I've some good 1.5ohm 1watt flameproof resistors, so i want to use them. For zobel capacitor i'm going to use 0.22uf 100v wima.

I am working on troubleshooting what appear to be high (+10v) B voltages at the PS board outputs. What I have done so far.

1. Replaced all electrolytic caps and upgraded film caps

2. Replaced bridge rectifiers 3 bolt mount and 3 in board (1N4004's)

3. checked resistors and diodes in circuit and pulled a few. They all seem ok with DMM. Checked transformer output voltages 70 VAC and 33 VAC. Resistance at the B terminal on the driver/output boards is ~30M ohms. There is ~.5 V of AC measured at the B term. Measurements were made at idle with all boards plugged in and 8 ohm dummy at speaker terms.

Adjusted bias to exactly 50mV and output offset to 0 mV +-1mV and it is very stable. Scope shows perfect sine wave 100- 10,000 Hz. Clips at 46VAC.

My questions are:

1. Is a 15% voltage increase within design spec tolerance ? Seems high to me.

2. Can anybody tell me what the transform output AC voltages should be?

3. Can resistors measure properly at low voltages and fail at higher voltages?

4. What other checks can I do ? Is it possible the Driver/ output boards have too much resistance or draw too much current and I should go through testing them? What should the total idle resistance or current draw be by the amplifier? Seems odd that all 3 boards have issues, but I suppose if the PS electrolytics went bad then the boards may have all suffered equally... thinking more that the issues are in the input/output boards, which are one in the same on this design. I'll start by testing the transistors and move downstream. Just bought a Peak pro tester.

Other symptoms of the amp which seem off are the FETs get hot and the sound seems just ok, but should be much better. My updated GFA-555 sounds much better.

Update: After pushing it a bit (running 3 fans down drafting with a variable power supply) to the Dunlavy SC-IV's and SC-S2 sub it is sounding quite a bit better. I think all the polypropylene the film caps needed some burning in..... Wonder if these caps will lower their resistance after burning in ? - wouldn't think enough to affect the I*R parameters enough to affect B voltage.

Thanks

I have for sale an original Rotel toroidal transformer pulled from an RB-1080 power amplifier rated 2x200W. Can be used from 220V or 110V. I measured the secondaries without load 2x55V and another one 12V for standby module.
It also has shielding between primaries and secondaries and a wire to connect to chassy. I have the schematic if you are interested. The VA could be around 800 judging by the size.
PM for more info

Hello
Looking for all the Mosfet Output Gurus; I'm sure You will know the answer!
Attached is the hand drawn copy of a Well-known Mosfet Band amplifier which was designed here in New Zealand years ago, and is known to be virtually bulletproof.
Because of this, I just went ahead and copied the circuit and produced my own PC boards as I have done other times.
The only change from the original is that I am using Hitachi 2SJ56 and 2SK176 Output devices, which I had a few of. The Original Devices were BUZ901 and BUZ906. I did not need the 400 Watts of the Original circuit, so I am only using 2 Output Devices instead of 8 per channel.
I carefully checked the specifications of these substitute devices to find that they were indeed very similar, before I started construction.
The amp sets up perfectly and is very stable. The Quiescent Current in the output devices is about 4 mV measured across the .22 Ohm Resistors, which is of course 0.0181A or 18 milliamps. The circuit as it is has no way to adjust this value.
The problem the amp has, is that when you apply an Audio Input circuit, the output is quite distorted and the Output Devices immediately start to heat up, even though they are heatsunk to a good sink. Thus far, I have not supplied it with a sine wave input to be able to examine it's output. Maybe I have missed something important, maybe the substitution of Output Devices? I was looking for a simple circuit -- maybe too simple?
No doubt someone will have the answer!

I want to run a bass bins in parallel with my 2-way loudspeaker.
I'm a mid-bass head and sit far away.
The 2-way has an 18db crossover (3 pole, 1,200hz).

Can I run 6db rolloff (single inductor assuming flat z-curve) on the midbass modules (can be seen as baffle step woofers even) and it will be in phase with the woofer ?

I may have to flip the polarity…….


Love my 2-way, just want more punch impact like my double 15's had...…...

Anyone know what all 4 of these ic’s are ?

A guy sent them to me saying they are defective and wanted me to rebuild the boards for him .

Hello,

10 years ago I made a amp with two STKs 4241 II.
A few months ago I decided to rebuild it ,since the first build was hasty and had some noise.
I finished it a couple of days ago and it works fine except some issues.

First one is that there is too much treble.I connected a pre amp I made with a NE5532 and I have to cut down 20-25% of treble to make it sound good.That happens either with the preamp(without cutting down treble) or with a signal straight to the amp.
I guess it has something to do with the input capacitor.Everything on the board is what is stated on the datasheet so the capacitor is a 2.2uf.

Second problem is a bit of a hum when nothing is connected but that's not too annoying,as it's not too loud.It could be a ground loop and I will check my grounding again.Note that I star grounded everything.

Third issue is that when input is connected then more noise appears,at different frequency, that increases when I increase the volume.The volume is adjusted by a pot connected to the RCA.Could that be RF interference?Note that the front and rear of the chassis are plastic as they are 3D printed.Chassis is grounded.

I will upload later some photos from the amp and a drawing of how everything is grounded.
I have a toroidal 600VA transformer ,two STKs on 2 different boards,the input signal cable is shielded,however some 220V cables are nearby so that could be the reason for my second problem.

Thanks!

Was wondering if anyone could tell me if the Sophia electric globe or st shaped 45's will fit in the original tse without the bulbs touching?

Thanks.

Anybody knows if there is a tube with single section, that is electrically equivalent to 6SL7? Also a single section equivalent
of 6BL7?

Alex Deveza

Got an old kenwood cassett deck .

Unit will not power up fuse is good .

Wondering if the IC that controls the speaker outputs also controls the unit to power up ? TA8263BH

Or am I looking for something else as to why it won’t power up

I recently wanted to split 24 volts into 2 12 volt rails from a 24DC power supply wall wart.
The circuit below seems to work very well.

I would like to introduce and recommend a neglected 6SN7 substitute, the Raytheon
5694. It's a made for the military dual AF power triode. The 5694 = premium 6N7 GT
with separate cathode leads, like a 6SN7. It is similar electrically to a Mullard ECC32 /
CV-181, BUT with a different pin-out. The Raytheon tube actually is closer electronically to a 6SN7 than the ECC32s are. The Vfil = 6.3V @ 800ma, versus 950ma for the ECC32s and 600ma for a 6SN7 GTB. These tubes although rare can still be found for between $15 to $50 each delivered. My yield of platinum (5%) matched and balanced pairs and a single quad brought my price per tube to about $100, still a great bargain considering the fact that they are far superior to the $500 to $600 plus a pair of Mullard ECC32 / CV-181, when and if you can find them.
Raytheon has accidentally and unknowingly given the audio world a great gift.

These tubes are far less noisy than the ECC32s and deliver details like a Jazz piano with no close rival. The silent passages are as mute as you have never heard. They are also much easier on the ears, allowing for longer, more pleasant listening periods. I found the Mullard ECC32 lacking in bottom end response. My previous
6SN7 favorite flavor was the "holy grail" of the 6SN7 world, the Tung-Sol 1940s
6SN7 GT, black glass, black plates, round getters, fetching $400 to $500 a pair, when and if you can find them. Not being sentimental or indecisive, my barely used quintet quickly fetched $1,000 on the slightly used NOS market.

They require adapters or re-wiring of the octal sockets they are going into, but it's more than worth it. The required pin-out follows: Pin # 1 Cathode, 2 & 7 Filament,
3 Plate, 4 Grid, 5 Grid 6 Plate 8 Cathode. IF your making adapters, use the following pin-out. Tube base number / Tube socket number: 1 / 4, 2 /3, 3 /1, 4 / 5,
5 / 6, 6 / 8, 7 / 7, 8 / 2.
Good luck treasure hunting, I humbly await your opinions.

Amplifier with no adjust (offset, bias) +/-60V. Simple to build, no oscilation, hum and noise. Praktik, usuful and good sound.

Ordered the PCB and the first component today.
I like the sound from my Marantz CD-60, even if it's only partially modded, so I wanted that sound for my PC too.
This build will take some time as I'll gather parts as I can afford them..

DAC PCB


SAA7220P/B


and finally