Hello all,

I hope everyone is doing well during these times.
This is my first post and a call for help, so I appreciate everyone`s input and wisdom greatly.

I have built my first ever tube amp, a SE design from Popovich`s book on tube amps, and build a power supply for it from scratch. Now I wasn’t 100% sure of the power supply for this amp, but the idea was to supply all voltages from separate windings, with bridge rectifiers for each circuit, as they are cheap and available. Upon the turn on, to have only heaters and negative bias on, and then via separate switch B+.

I fed 2Vpp 500Hz sinewave signal from the signal generator to the amp, after the preamplifier stage it gets to 31Vpp, looking all good, after passing through one half of 5687 it is amplified to 50Vpp, but with the top of the sinewave well flattened.

While testing voltages without any tubes in the amp, the voltages vary quite a lot, but with all tubes in voltages drop closer to intended values +-10%.

And now the part that throws me off, is the driver and output stages. The driver tube`s grid has the correct negative voltage and seems to be all fine, but the cathode of the driver tube has reversed polarity, instead of negative as in the schematic I get the same voltage positive? Even it is connected to negative voltage?? which effectively makes output tube`s grid positive 😕 Why does this happen? I have a feeling that I must`ve got something fundamentally wrong here, but after the amount of time spent which is equal to wanting to smash this thing to pieces, I can't really find the answer .
I tried to troubleshoot with the test lamp to see if there are any shorts, which there weren’t any. I double-checked all solder joints etc. and all seem sturdy, checked all the connections. I did try to change up a bias and driver`s power supply a little (version 2) where driver plate and negative bias were fed from the voltage doubler symmetrical circuit, to see if this makes any difference, but nothing. Did some other various changes to the power supply, but the result is the same,
I would really appreciate any help to get some output here.
Thanks,
Karolis

This in memoriam section is reserved for diyAudio members who have passed away. You may also post the deaths of well known people in audio industry.

Please post musicians in the Music forum and anyone else in the Lounge.

I listen to this just now: ( from Original CD )
http://www.youtube.com/watch?v=V3JSDUOcG7M
CREAM: We're going wrong
(Jack Bruce)
Please open your eyes,
Try to realise.
I found out today we're going wrong,
We're going wrong.

Please open your mind,
See what you can find.
I found out today we're going wrong,
We're going wrong.

We're going wrong,
We're going wrong,
We're going wrong.

Gyuri.

PS.
I hope for it meanwhile, that possibly maybe not, after all.

Looking at a EAR V20.

One channel has mains hum and crackling for about 2 mins from Switch on.
Only happens from 'cold'. If left over-night.
Once on and OK can be turned off and back on and will be OK. If left off for even an hour, will be OK.

All Valves (24x ECC83 + 2x ECC82) and Electrolytics replaced.
Still the fault remains.

Any thoughts appreciated.

P.

I appreciate that these are not exactly new devices, but I needed some complementary MOSFETs that would work well at 24v Vds and 10 mA Id and I could not find many choices. The application being for a headphone amplifier based loosely on the Sony VFET front end in case you are interested.

First problem was finding any N/P matches. Based on a relatively small sample (3 lots of 10 each from different suppliers) I obtained a range of Vgs values for the above conditions:

• 1.928 to 2.205v for ZVN3310A
• 3.351 to 3.510v for ZVP3310A

Not even close! Are my samples unusual or are these devices poor complements?

Just as a check I measured Vgs threshold (for 1ma Id) and obtained:

• 1.35v for ZVN3310A
• 2.0v for ZVP3310A

Consistent with the above results but less than ideal.

It also looks like the transconductance of the P part is rather less than that of the N by comparing the additional Vgs above the threshold required to reach 10 mA Id. However, I did not verify this as I don’t currently have a suitable test rig. The manufacturers datasheet is also of little help at these low currents. Long shot I know - but has anyone with a curve tracer measured these parts?

Finally, my devices exhibit a significant amount of self-heating at the desired operating point despite this being approx. 240mW when the device is supposed to be good for 625mW at an ambient temperature of 25C (close to the temperature here today). I guess the e-line package is rather small… So far I have tried introducing 221R source resistors but these appear too small to prevent Id from creeping slowly upwards. I suppose I shall have to increase the value but I don’t wish to go too far due to the associated voltage drop and hence reduced swing from the front end of the amplifier. Any suggestions?

I would prefer to stay with MOSFETs rather than introduce BJTs hence also interested in suggestions for suitable alternatives, preferably ones that are actually obtainable!

Good morning.
Are any of you aware of the capacity of Acousta Monitor 4 single cell?
Thanks all.

Greetings!!!

So...two months ago I was writing a file to my unit and somehow the RS232 cord came unplugged!!

From that point on, the unit will not connect through the software. I can put the unit in boot mode but still nothing!!

I cannot write to it or read from it!!

I contacted behringer...they were zero help...told me to take it into a repair depot!! Well I'm an electronics guy as it is and the repair depot owner is a friend of mine!! He contacted Behringer and he had zero luck!!

With that, Behringer did provide me with a part number to order a new flash...so I did...$25.00!! And guess what?? The IC came blank!!! Nothing on it!!!

Like I said, I work in the business...I have an eprom burner at my disposal...and before you ask, yes, I put the original chip in but whats the point...its corrupted so the read from it is useless!!

I took the 1.6 bin from their site and wrote it to the blank...I thought what the hell but it still didn't make sense as the chip is a 4 meg and the bin file is only 500k!!

Seems that Behringer doesn't understand this concept as well...

So any ideas??

My unit was date stamped at 09/06...

Behringer did say that midiox may work in sending that 1.6 bin down to the corrupted chip but I have no way of working with a midi connection.

Can anyone help or suggest something??

Thanks!!

Hi my name is David i live in kent in the UK i have a hobby restoring old valve sets TVs and a pre war MG when i get the time ! . I gained a HNC in Electronics many years ago from time to time fixing modern stuff to save the environment and achievement thanks

Hello to the community. The thing is- i have lundahll 1664 transformers se with 100 ma. I’m about to build se amp based on these transformers. They suit for both 2a3 and 300b. Currently i keep an eye on sun audio schematic as the standard one. Would anybody suggest better schematic for my needs? I’ve already simulated everything in orcad pspice and everything goes ok, ready to build pcbs. But.. maybe there is a more decent application? Your suggestions are highly appreciated.

hello, anyone has sony cdp-3000 service manual, searched all the web couldn't find anywhere.

I just got today a Rigol scope for a good price but it came sans probes. It is a 50Mhz scope. ( It is my first scope.)

I see some affordable ones online but mainly they state 100mhz. Are they compatible?

Thanks

I found this preamp board on Ali that has most of the features am looking for. Confused about a few things. The diagram is really low resolution.

1. Failing to see the subwoofer output, does it come out of the 5 pin connectors? If so will a 26AWG connector suffice?

2. Would like you use the same power supply for amp board. Its asking for this. " Power supply + v G -V is the power supply port, connect positive and negative dual power DC +/- 12v, or +/- 15V." Planning on getting a Mean Well LRS-350 9.7A.

a. Does Dual power mean something else beside + / - V and ground?
b. What is the best way to reduce the voltage from the powersupply?

(will this work): I was thinking about using a LM2596 DC-DC Adjustable Buck Converter 3.0-40V to 1.5-35V Power Supply Step Down Module. But It states "Keep it under 2.5 A and use the heat sink when working for long hours." Does this mean I have to reduce the AMPs before connecting it? There is no ground on this Converter, do I just use the ground from the power supply? Do I even need a ground?

Thanks

Hi guys,

In 2007 I bought a second-hand Sherwood TEMA A-1 and TEMA P-1 power and pre-amp combination together with an Advance MCD 203 CD-player and Paradigm speakers from Athens, Greece.
Up until this year I have been lucky enough to enjoy listening to the great sound of the TEMA amps.

Unfortunately a few months ago the TEMA A-1 stopped functioning. After a lot of work and effort I managed to figure out that there was a problem with the TOSHIBA IGBTs.
I searched in vain to find spares for these and was told that this kind of technology is now obsolete. The response to my queries from Toshiba Electronics Europe GmBH was that these are discontinued and are obsolete.
I've tried Sherwood US but they didn't seem to be able to help.
I've also tried contacting INKEL in S.Korea but they never responded.

Can anyone help me find a couple of TOSHIBA GT20D201 IGBTs?
I think that the Palmer LX 2000 PA Power Amp also had these iGBTs.

Any ideas/tips?

Many thanks

I have this desk for recording with my Fostex E-16 reel-to-reel.

Some time ago I fried something in it by connecting a faulty active monitor into the right master XLR-output. There was an awful loud sound and I quickly turned everything off.

After turning the mixer on again, all that was heard is a steady clicking noise from all the master outputs, including the headphone.

Aux, talkback and groups work normally. My general suspicion is the faulty monitor gave mains back trough the main outs.

Taking it open I found this fried lead behind the op amp (see attachments mixer 1 and 2).

In the schematics, it's the lead right after U3's leg 6 (attachment monbusspcb).

Full schematics can be found here:

https://elektrotanya.com/tascam_m-25.../download.html

After making a jumper repairing it, sound started coming trough the input channels, albeit quiet and when taken to overdrive, the clicking returned but at least with some sound (see video).

Tascam M-2516 problem - YouTube

I proceeded to cannibalize two op amp chips from the talkback replacing U2 and U3 IC's as well as replacing caps C7, C8, C104, C106, C204 and C206 with no change in the problem.

Personally I've hit a bit of a brick wall on to where to look next so I was hoping someone could guide me to the direction maybe from the video sample and the description here.

Any help is much appreciated!

Thank you in advance,
-ekkhou

First of all props to the basis of my design, beeing ThatMicPre!
Really nice circuit!
For my case however, I need digital control, but I also want to avoid small QFN parts...

So I started CADing a modified version. I added:
-Gain control using the DG412 switching IC (according to this paper)
-Digitally controlled phantom power
-Line in with combo jack

One downside is that the full 60dB gain can not be reached, because of the high on-resitance of the DG412...
How would you solve the task of digital control?


I would really appreciate any feedback on my edits.
Are there simpler solutions to this?
Any tips and tricks are very welcome!

Hi,

Can someone help confirm the $399 silver faceplate option is the right one to allow this mounting?

And can you confirm if the LED hole is not actually a full hole (as in, it does not penetrate the front of the faceplate but could be drilled out later?)

I just want to be 100% sure before ordering. Thanks!

Deluxe 4U Aluminum – diyAudio Store

I was today with a friend (called Humbledeer down here) working in my workshop. I had on my rack a few old Philips AD1065 M4 drivers, of which one had a broken lead. Humbledeer fixed it and we put it in my old subwoofer cabinets originally made for a pair of Scanspeak 26W8534G00 drivers just to test how they sounded. And that actually sounded quiet good. It's a 150L ported cabinet originally tuned to about 25Hz of long ago. We are going to use them as workshop speakers now (that's why they got a gril. But it was pure luck, and i'm sure they are not tuned like they should. But there is quiet a lot of bass, more than i expected from these old drivers and a very balanced sound.

Of course no measurements, and we will not even bother to do it. It sounds better than we need in the noisy workshop. And that for 0€/$/ as all parts are leftovers or recup from other builds...

edit: the picture does not want to show right angled, how i turn it (admin?)

I have constructed a driver stage and I would like to share the results. It is a variation on the mu-stage. Inspiration for this came from Alan Kimmel and from several threads on diyAudio recently. http://www7.taosnet.com/f10/mustage.html

Though not an SRPP, the circuit resembles one. It has a pentode as the upper device. Rather than mirroring the lower device in the way an SRPP does, it behaves more like a constant current source due to the increased gain of the pentode.

Some may not like the idea of using a pentode. I was hesitant too.

The voltage gain device I am using is the 46 recommended to me by i_should_coco. I have grown quite fond of this device and it doesn't let me down here.

The pentode is the 6CM5/EL36 which I chose for it's transconductance of around 14,000uS, and because of its wide Vhk capability.

Here is the circuit (grid stoppers have been omitted for clarity).

Hello everyone,

Some time ago, I asked in this forum some advice on how to go around rebuilding Tannoy Arden (Legacy) Speakers and any advice on building a Super Tweeter.

Orginal posts here

and here

The build is finally complete and I am adding some photos of it to share with forum members

20210825_143338.jpg - Google Drive

20210825_150539.jpg - Google Drive

20210827_153457.jpg - Google Drive

https://drive.google.com/file/d/13auUlG-W0mc6-KrtNLB18j7XF1c_CiA8/view?usp=sharing

https://drive.google.com/file/d/126Y5aiedX_nqixJ40v7d8xC4vjBnKf6_/view?usp=sharing

https://drive.google.com/file/d/1YnA1amcQ37ETms0g8_0fOPtHqCibI9DL/view?usp=sharing

https://drive.google.com/file/d/18hxyJXJVC1hOJL7VpUzN-q5u8GUKkEGk/view?usp=sharing

https://drive.google.com/file/d/1nNDMe7CneqCBesht-5UnKlV-P9GlkD64/view?usp=sharing

https://drive.google.com/file/d/11Ox_u1t8KYG75KIN0xAapL9e1cLDJ7Of/view?usp=sharing

https://drive.google.com/file/d/1cG1Mbxa-8y6e1BaE8738_NAfoJqnXpjo/view?usp=sharing

https://drive.google.com/file/d/1G_4g-MCJzxxJGdiYLUyooDukgjG_9sts/view?usp=sharing

https://drive.google.com/file/d/1ufUCTYpdeFis9PVFd5Rmwwik0TB1Lv4s/view?usp=sharing

https://drive.google.com/file/d/1qNNUogybhMQ_WC9fG-xziTF_SffGcz6r/view?usp=sharing

https://drive.google.com/file/d/1nsYAqdQv6SMICexVBV2CwT-j0vHttepa/view?usp=sharing

https://drive.google.com/file/d/1myhuqnfgkdHFNG3wkyq9LiD2We6bYF9C/view?usp=sharing

https://drive.google.com/file/d/1_Sv0oHl0AwwDgAcdTLSFCqAM_PsZfdbM/view?usp=sharing


https://drive.google.com/file/d/13kkfPOAERIhG85ca53o57Dqh-FEP5Bq7/view?usp=sharing

Hi,

I have both tweeters blown on my pair of HB2's. Looking closely the fine wire between the terminals and the coil has corroded and broken a couple of mm from the coil. Can I repair this (e.g. solder together)? I know I can get a replacement tweeter on Falcon Acoustics but that will set me back £50each, so I thought I would try a DIY repair first.

Any thoughts or advice appreciated.

Ed

PS Anyone know what a Heybrook Trio speaker is? Is it similar to the HB1? Is it any good?

And vice versa. I have the SB16PFCR25-4 on hand and I'm interested in Michael Chua's projects that use the 8 ohm version. Rather than purchase the 8 ohm version, is there a simple adjustment I can make to the crossover to allow me to use what I have? Thanks for any and all suggestions. His contributions to DIY are amazing.

Has anybody built this 300B/6SN7 amp advertised on eBay?

Link to eBay.

First post, and first speaker project.. 🙂

I've been reading an learning a lot over the last past weeks about speakers and XO design and time has come for a first speaker project.

So, here's the story:
I bought a pair of Dual CL140 speakers in a second hand store some time ago because I liked the 70s look of them..
came home, hooked them up to my Marantz 2275 remote speaker output, they sounded ok but very little bass. A few weeks later my flatmate had a party while I was away for the weekend and her boyfriend turned up the volume knob and... blew up the speakers. Came home, apologies were made and accepted, he payed me back the 40eur/50usd that they costed me and I ended up with nice looking bookshelf cabinets with broken woofers laying around.
The cabinets have an internal volume of 15,35L (0.54cu.ft) and the woofers cut out hole is 175mm/7".

Now, I decided to use these cabinets to build the speakers for a chinese el34 DIY tube amp kit thats on my way atm, similar to this one:

https://www.diyaudio.com/forums/tubes-valves/182989-building-chinese-se-el34b-amp-diy-kit.html

I allready ordered it before reading here at DIYaudio that it is actually a cheap piece of junk, but since I ordered it for the fun of learnig and tweaking it in the first place it should meet its purpose.
Anyway, in the end it should serve daily to play music in the dining room/ kitchen.
Thats is a square 60m3/2100ft3 room.

The amp is stated to have a 13W*2 output, 4ohm or 8ohm speaker connections.

If I did my homework right it should pair well with a pair of speakers with a fairly high sensitivity (around 90dB/W), impedance drops should be avoided and the curve should be more or less flat.. ??
At first i searched for DIY speaker kits that matched needs, then decided it would be more fun and I would learn a lot more by starting my own project.

The speaker built should meet these requirements:

- Stick to the CL140 cabinets (15,35L internal volume)
- Woofer size should be 7,5" or 8" if possible (the cutout hole now is 175mm/7" and making the hole bigger is easier than smaller)
- Sensitivity of 90db/W (the more the better)
- Bass should go low enough
- Impedance friendly for the vacuum tube amp.

I pretty soon found out that its not easy to find a solution for every of the above requirements and that the solution might be found in a compromise, so this is what I came up with:
I used Dayton Audio drivers, just because they have FRD and ZMA files easily available that I can load into VituxCAD

RST28F 4ohm tweeter
DSA215 8ohm woofer (I tried many many woofers and got the best results with this one... low bass/flat FR/high sensitivity is not an easy combo)
A ported 15.35L enclosure with diameter 40mm, 140mm long port should give me an acceptable f3 of 56,6 Hz/ f6 43,6 Hz/ Fb 38,0 Hz

What are your thoughts, feedback of what I've got so far?
All comments, advice are very much appreciated.


Am I on the right track here?
Is the impedance curve acceptable? because I just cant get it flatter without messing up the frequency range.
Is that bump around 900Hz something to be worried about?
The overall sensitivity is around 89dB, will this be enough for the amp?





I attached the curves pics..
3rd pic is the enclosure SPL with the XO applied to it.

Is the pictured type of mic cable unsuitable for wiring the input signals in a power amplifier chassis? It is called "Rapco CM Rated Installation Grade Mic Cable":

Rapco CM Rated Installation Grade Mic Cable | Musician's Friend

Such as wiring from the RCA to the potentiometer board? And then the potentiometer board to the power amplifier boards?


I ask primarily due to the foil shield type construction. Is the resistance too high? Or the shielding (foil) not optimal/not suitable? From reading the following link (slide 31) should I purchase a different type with a heavy braided copper shield instead?

http://hifisonix.com/wordpress/wp-content/uploads/2019/02/Ground-Loops.pdf

I ask since I am trying to reduce hum (and a THD increase) that occurs when both inputs are wired to the amplifier boards in a stereo configuration. I think a loop is occurring as per slide 36 of the hifisonix document. I wonder if it is worth trying to reduce the resistance in the loop (with lower resistance interconnect) or whether I should simply switch to dual power transformers and dual rectifier/filter boards or even a mono-block configuration to avoid the loop.

Here are measurements with and without the suspected ground loop:

https://www.diyaudio.com/forums/sof...stortion-measurements-rew-96.html#post6781170

Folks,

I have two things - and I want to get them to work together if I can. I have a pair of Bozak 302 “Urbans”, in very nice shape, though the tweeters are gone. I ALSO have a pair of Stephen’s 15” trusonic coaxial drivers. These are the 206 AXA models with crossovers. It seems to me I can remove the baffle from the bozaks and shoehorn in a new one, with the driver placed closer to the top of the baffle and some ports at the bottom.

My worry is that I am told that’s just not enough volume for 15” drivers. The bozak’s are 24 x 24 x 22 = 12,672 cubic inches. HOWEVER, the Tannoy Ardens (which also use 15” drivers) are just 36 x 24 x 14 = 12,096 cubic inches. Ie, 12,000 cubic inches would seem to support a 15” driver in a bass reflex enclosure. Where have I gone wrong?

Hey Guys! I had an arcing sound with bright flashes in my own 100B but after checking capacitors and wiring, I put it all back together as I found nothing wrong, well the arcing had stopped. Then I had another 100B in for service with constant arcing which was down to the -70V bias wire breaking down to the +500V rail. Out of curiosity I removed the bottom plate of my 100B and sure enough the infamous Black wire was laying on the end cap of the 5k1 resistor. Careful visual inspection shows some strange discolour of the wires Black sleeving just where it lay alongside the resistor end cap.
I know it is a bit of a pain, but I would recommend you remove the 34 screws 🤬 and check, upon removing the bottom panel, that you do not have the dreaded Black wire draped on top of the 5k1. This is only a problem it seems with early models and I personally think the wire used has insufficient voltage rating. Remember it is the Right Channel but of course it is on the Left Hand side when you are looking from underneath with the front panel towards you.
Here's what can happen if you are unlucky.

http://www.g4cnh.com/public/100B_spark_up.mp4

Super Transconductance Tubes

Thoughts

Hi.

I need help figuring out the port size that would be required for a series 6th order bandpass box with a custom sundown nsv3 18.

I don't have the specs yes, but I have been using the parameters for the nsv4 18d1 found on sundowns own site. I'd think this is rather close and I'll have to re design the box anyways.

I just need to know if I'd have space for a 6th order in my trunk at all.
I have modeled that a 200-250l ported enclosure tuned to 25-30Hz should just fit. That is what I'm going with if I can't fit a 6th order.
The problem is I have 8kw rms of power and I need a very large port for this.
In the ported design I can get the port air velocity down to about 30-35 m/s, which I think is pretty good for that much power.

I'll be using a 20Hz HPF or something to control the xmax to 45mm.

Now I have tried to design a series tuned 6th order in hornresp.
I have a start with 160l front chamber and 80l rear chamber.
With the rear chamber tuned to 25-30hz and the front chamber to around 70hz.

The goal is to get more sensitivity and a wider frequency range with the 6th order, as this is going into a car, that will boost the lows maybe 15dB+. So I want the hard hitting lows with a little more highs for a flatter response.

But when I have a good looking frequency graph in hornresp, the port air velocities are through the roof. like 60-80 m/s, and seem to need upwards of 3000sqcm of port area to get it down even a little bit.

I don't care about chuffing because I can't hear that in the car. All I want is a nice response that doesn't get too much port compression at 8kw.

How high of an air speed can I have for this alignment? I need to stay under about 350l of total air space for the enclosure, maybe even more like 300l.

Hi,

I currently restore a Sony WM-D6C Walkman, and there is broken 3.5mm Jack, that seems to have unusual dimensions: see the attached photo, it is the RED one.



Replacing this broken jack with one having a different size would be a nightmare, so :

do you know where I could buy such a 3.5mm stereo jack ?

Thank you very much,

I’m currently building an f6 and am making use of an lm 329(6.9 v) as a voltage reference. I’m curious what size resistor to use at R7 & R8? Is 3k3 adequate?
I’m using an Antek 400 va with 18 volt secondary. What is the formula for determining ideal resistor value? I’ve got some 3k3 metal film 1/4 watt on hand but can order perhaps 3.9k? Not sure though
Thanks

I really enjoyed building the ACA, and Bottlehead Reduction kit. I know there are some other audio kits out there (like the Elekit and Sunvalley stuff)

Even if not audio-related, are there other DIY kits that you would suggest?

Thanks!

Hello fellow Denverians out there. I myself live in Highlands Ranch. I wish to ask if any of you know of a good Speaker repair shop. I have had for many many years (2000) a pair of Infinity RS-10 floor standing speakers. Today, I noticed that one speaker is exhibiting a "crackling" (distortion) coming from the Subwoofer. I suspect that the built in Subwoofer amp, is dying, because swapped cables, reversing channels on the amplifier has not solved the issue and have determined that the problem is in this area. The tweeter and the mids, are working fine..its only the sub that is producing this horrible noise. I hate to cut loose of these fine speakers and hoping that I can get the amplifier repaired..
Any help will be greatly appreciated.

I have a Dynaco SCA-35 that I've re-done for and with my son, using the Dave Gillespie update boards.

On the whole it has turned out great but one problem I'm left chasing is the balance control, which keeps going intermittent despite being carefully disassembled and cleaned.

Since 750K M-N taper balance pots of high quality appear to be as scarce as unicorns, I am looking at putting in an 11-step 2 pole rotary switch, with resistors.

I recognize that to work like an M-N taper, each deck should have six of the 11 positions with no resistors, in mirror image (opposite directions) to one another, with the center position having no attenuation of either channel.

I also understand that the "taper" of the remaining five positions that will have resistors should be logarithmic, but that's where I start to get lost - abstract math has never been one of my areas of skill/comfort.

Can anyone please advise how I would "taper" 750K over five positions to work like a logarithmic balance control? Or a "for dummies" way that I could calculate it?

Thanks in advance!

Got a REL T3 subwoofer with some resistors that I can no longer determine the values. Any chance anyone has a service manual/circuit diagram or the actual amp for reference?

Hi All,

Had a decent read of many posts and I think this is the correct way to wire my Hiraga build. Just a hobbyist so looking for confirmation this looks ok. My main query is in regards to the IEC safety and the circuit/star ground. Is there continuity between the two ? Hopefully picture comes through.

Thanks in advance

Richard

Hello everyone,

the M-audio transit, http://www.m-audio.com/products/en_us/Transit-main-1.html is a 24/96khz adc. dac and digital i/o box

Has anyone got one they can take an internal picture of? I'm hoping it is not one FPGA, etc, so I can tap into the i2s data lines.


It would make a great 24/96 reciever for a dac, (and tx for a adc) if one could tap into the i2s lines. here's hoping


Regards,
Mark Hathaway

Can anyone please enlighten me as to the purpose of the 2W 56ohm resistor in this cct? (The LED illumitators also have a 2W56ohm resistor in series)

Also IN4002's getting pretty warm, would a higher wattage diode help?

Obviosly 7812 is maxxed out, especially when tubes are cold (heater resistance I believe are 15ohm cold, 80ohm hot)

Decided recently to build the Classix II (and learn along the way about crossover designing). Thought about putting the exact components for the Classix II build by Paul Carmody on VituixCAD and the response graph is completely different than his!

I have used the official FRD and ZMA files for both drivers. What could the problem be?

Can you please tell me which permissible scatter in sensitivity can be between a pair of tweeters? For example, on Twitters Dayton indicated 89 0.2 and 89 0.4 This can be considered a selected pair? Or for example 89 0.2 and 88 0.4 This can be considered a selected pair?

If you follow the thread on building a class A amplifier here:

Single gain stage transistor amplifier.

you may realize I am continuing to have fun dabbling with the 'single ended' transistor amplifier with some measure of success. Distortion levels vary, possibly due to bad connections, so I need to re-do the circuit again (solder-less of course). Sometimes I am able to listen without much distortion at all on the desktops, so the concept is workable.

As you can imagine, I am getting a little impatient, and tired of listening to the right channel only or left channel only on the large floor standing speakers or the smaller desktop speakers I have. Wouldn't it be nice to hear the sound from two speakers, albeit in mono? Is it possible to convert a stereo signal to mono? Happily there is a way to do this, and readers will probably know all about it. Some testing with the said class A amplifier and the ES 333 speakers in series provided a good level of sound, and relatively similar to the stereo music I have heard, although the amplifier needs to be improved greatly.. I am more comfortable listening to two speakers in mono rather than one speaker, there is more sound and it does not seem to come from a narrow corridor on one side of the room. To listen in stereo you have to be in the 'sweet spot' that varies by speaker, of course. There are other benefits, in depth and sound stage, although you can hear the stereo effect when seated to one side of the speakers, much of the time spent listening is in semi-mono. The 'stereo/mono' switch on FM tuners is another feature which readers will be familiar with, and it does not render the radio station unlistenable to.

Here is the proposed system: the simplicity of putting together a mono amplifier circuit, single channel, and listening to music from two speakers is a quick fix that is difficult to pass up. I can do all the listening tests and enjoy the music at the same time. One circuit, one power supply, one transformer, etc, at the cost of some input resistors and some wiring to add the L and R signals together.

I have not been able to find any threads on DIY audio that are related to this concept and I was wondering: is anyone listening in mono over two vintage speakers (Bluetooth speakers do it all the time).? Any advantages?

Hiya folks,
I've just picked up an old Playmaster 200 I'd like to refurbish. One channel works fine, the other sounds dead - but there was some warmup "rustle" on the other when turning the bass control, so I think both output channels are good. I haven't started troubleshooting yet, I had hoped it was the balance pot but that checks out OK, although a bit odd - it seems to be 2 linear 10k pots where the range works zeroR to centre then rising to 10k for last 1/2 turn - mirror image each side - presumably to keep crosstalk down. Don't fancy finding a replacement for that, will probably go with Left and Right volumes if it's an issue. BUT! Does anyone have a copy of the circuit diagram, or even the construction articles? I though it must be on the net somewhere, but a couple nights on google haven't found anything... cheers,
Terry

Recently,


Hypex has released a new firmware (1.45) which fortunately corrected some annoying bugs but introduced a new one : on previous firmware, green led was blinking when fusion Amp were muted. It's is not the case anymore...

Hope a pilot can identify this craft.
I took the pic just after sunrise in IAH airspace.
The more I study it, the list of questions gets longer.

-Angle, time of flight should be visible strat layers or else speed was verrry high.
-what is the rolling all about, it continues entire path.
-what is the 'bubble' at launch
-must be unmanned but in a metro area?
- heading is N-NE
- no boom heard.
-what engine makes a flat wide trail?

The attached pic is original taken with a windows phone

Hi All,

I am fitting a 100 ohm Humdinder pot to my 15w amplifier. Heaters are 6.3v and take just over 2 amps.

Is it okay to twist all three wires together (6.3v pair plus ground) that are going to the three pot terminals, or should I just twist the two outers (6.3vac pair) and leave the ground out of the twist?

Your advice would be appreciated.

Roger

Hi there.

I've looked at the previous topics on Horn Resp and cannot find the definitive answer to the following..:

Does the 'acoustical power' window of horn resp tell you the 'shape' that the horn loading is adding to the manufacturer's curve?

Or is it giving you its prediction of the actual frequency response (presumably 'measured' at 1m on axis)?

Thanks
Peter


PS thanks to all those who have contributed to my previous questions!

Hello,

Can anybody help me with a Russian/USSR tube plate cap like the one in the images? I only have one and I need two pcs. It's for tubes with 1/4" or 6.35 mm diameter caps.

Alternatively I would like to buy one pair or several such top caps but only of old production. I have a pair of Chinese current production caps and they do not make good contact.

Thank you!!
Marius

Greeting Audio Guru's out there. I was a massive home theater freak many years ago, and had a deep interest in Amps, speakers and Home theater. I was able to educate myself on the subject of home theater and was able to setup my own home theater system at home...Sadly, I faded away from this interest, and I do realize, 10 plus years away from this arena, there has been massive technology innovations. Its so comforting to know that you all out there have kept your knowledge and interest in this subject matter alive and marching on..

I design circuits for a living. Lately many semiconductors are hard to get as the supply, rightly so or not, slowed with the pandemic.
There's a new business model "Semiconductor Pirate". I can thing of two companies that are founded on it.
They research parts that are in demand and buy out all of manufacturer's inventory at once. They mark it up 100 fold and sell it on the open market. The manufactures issue a 50 week lead time thereafter. We OEMs have no choice but to pay it - oops there goes the profit margin.
I am inclined from here on not to design in any chips/module that are highly integrated - back to future I guess.
Has anyone else experienced this?

Purchased a parts unit Eight that needs the following :
* F-1278 driver boards
* Original chassis power cord recepticle
* large plastic tuning cord wheels and gears
* RH faceplate trim piece.. or complete faceplate
* Original service manual with Large schematic diagrams
* Eight wood case
Thanks,
Rapide998
Oregon

Hi,

Are these genuine Elna caps? The printing looks suspicious and I can’t really identify what cap line of Elna this is.. The seller describes them as “Elna S Gold”.. Thanks!

Well - this was not fun. Repaired my buddy's AR HD220 Amplifier, it had a blown bridge rectifier - replaced it and got it running, including a glitch with the soft start.

I hooked it up in my system and played it for a half hour or so, left it running, and went down to my shop to work on other stuff. After about another half hour my wife calls me and tells me the amplifier is on fire, literally on fire. Now if you look at the wiring that goes from the capacitor boards to the output stages you can see this is where it started they got red hot and the insulation melted and caught on fire - really why would one use wire like that inside an amplifier ?

It would appear that this was caused by oscillation, perhaps because I had it hooked up via 25 ft long RCA interconnects to a tubed preamp with a relatively high output impedance.

What i find extremely puzzling is that the right side input wire appears to have got real hot as well - or perhaps the wire insulation caught on fire from the hot wires below if - but really - why use wire with insulation that that can do that?

Now this could easily have been avoided with a set of rail fuses to each output stage.

Anyone have any input on this ?

Good Listening


Peter

I'm trying to mock up a new crossover for my Swans (hivi) DIY 2.2a
I found the Woofer (HiVi D6.8B) frequency responce and impedance responce as text files on parts express. I just saved them as ZMA, and FRD files. Is this how you're supposed to do it ??

But I could not find any files for the HiVi Q1R 1-1/8. Anyone???

Can someone help me design a crossover using the
Satori AT60NC-4 AMT Tweeter
as a super tweeter ?

Hello,

Long story short, I am moving to Europe from USA and have decided to take my Tannoy Arden Speakers with.

More info on these speakers here:

Tannoy Arden Loudspeaker (each) – Upscale Audio

Main specs are as below:
Frequency response: 35 Hz-30 KHz ±6 dB
Recommended Amplifier Power: 20-300 W
Power handling: 150 W continuous, 600 W peak
Sensitivity: 93 dB
Impedance: 8 ohm
Crossover Frequency: 1.1 kHz
Enclosure: Triple distributed port
Dimensions (HWD): 35.8" x 23.7" x 14.25" (910 x 602 x 362 mm)
Net weight: 41 kg (90 lb)

Due to shipping restrictions, I will not be able to take the cabinets, I am planning to take the drivers and rebuild the cabinets in Europe.
Not ideal but this is the best I can do at the moment.

So my questions are:

1) If I keep the same cabinet volume, but make the enclosure narrower and deeper, would I lose anything soundwise ?
2) The speaker has 3 vents, 5.5 inches wide, 8 inches long. Could I do two vents 7 inches wide and 8 inches long and keep the same tuning and sound characteristics ?
3) Can I move the forward facing ports to be rear facing and will this significantly change the sound characteristics ?

Anything else I should consider ?

Thanks

My first ever post here 🙂 So I recently felt like some nostalgia and got my old MF amp out of storage. But did it ever make some awful crackling noises - I then remembered why I stored it (probably 20 years or more ago!).

I also remembered that I was going to re-build the preamp stage which was a bit of a crazy design IMO but never got around to it. Well, now's the time. But first things first - I've got a full set of 105C 10,000U's to swap-in. The originals looked OK but they're just so old (and only rated for 85C which is a laugh in this Amp).

So here's the rusty article getting new caps:





Funny how the PCB is labelled A200. I think this was a fan-cooled product that got re-engineered into a bigger case and called A120 to make it seem like a big brother to the A1. The circuit is very similar but has a higher supply voltage and separate reservoir capacitors for left and right channels in a CRC filter arrangement. The output transistors are also doubled-up to handle the higher dissipation.

One question I have about this thing... see the black wires looped over the phono section bottom left in the first photo? They loop round to the underside and basically parallel-up with two short tracks coming from the MC/MM switch. They don't actually provide a circuit, they're just little "loop antennae". This just looks so random. Anyone got a clue what the story is here?

Anyway, as for my next job I'm going to bypass the entire preamp stage and feed the signal directly into the power stage just to see if there's enough gain to be usable with a CD input.

I'm familiar with the A1 mods described at www.markhennessy.co.uk but the pot position at the back of the A120 makes his approach less attractive. Instead, if I do need some gain, I plan to remove all the parts associated with the original quad op-amp and link the inputs/power/outputs onto a DIL socket inserted into the same footprint. Then I can plug-in a custom daughter board with an improved design. I'm not bothered about cutting the odd track here and there, the original preamp design is never going to make a comeback 😉

Hi,

I am taking the reference of LME49600 evaluation board design and modify it for my own. I change the opamp to be OPA627 and buffer to be BUF634. I use LME49720 for DC servo for both channels. I also change the feedback resistors so that the gain is 11.

I want to make the amp more stable and I am going to add a 10pF compensation cap for this design. The question is, should I place the compensation cap C3 in parallel with feedback resistor R4 (Diagram 1)? Or should I place it across the OPA627 output PIN and negative input PIN(Diagram 2)?

Qurtre Amplifier ???

As I was going through all my hidey holes of old Electronics I found a very heavy Qurtre Amplifier. I hooked it up and all seems well and works good and sounds good....But, I know nothing about this Amp as there is no name plate or other ID anywhere except the Qurtre Name on the Silver brushed front panel with one tiny red power light on the front bottom center. Any input as to what I have here is appreciated. Searched the web with basically no information.
Thanks
Bill😕

Sale:
1P24B — 2 pcs. for $1
2P1P – 163 pcs. for $1,
2P2P – 75 pcs. for $1,
2P29L — 18 pcs. for $1.5
2P29P – 96 pcs. for $1.5
4P1L — 20 pcs. for $4
6P1P-EV — 100 pcs. for $3
6P3S — 20 pcs. for $4
6P3S-E — 20 pcs. for $7
6P7S — 50 pcs. for $3
6P9 — 100 pcs. for $1.5
6P13S – 5 pcs. for $2
6P13S (hole plate) — 50 pcs. for $10
6P14P-EV — 200 pcs. for $10
6P14P-ER — 200 pcs. for $12
6P15P — 100 pcs. for $1.5
6P15P-EV — 100 pcs. for $2
6P18P — 200 pcs. for $1
6P21S – 28 pcs. for $3
6P23P – 16 pcs. for $1.5
6P31S – 6 pcs. for $2
6P36S – 30 pcs. for $3
6P37N-V — 17 pcs. for $20
6P42S – 14 pcs. for $12
6P44S – 28 pcs. for $2.5
6P43P-E — 10 pcs. for $2.5
6P45S – 20 pcs. for $18

I got a very trashed Sony CDP-215 a super basic mid 90's player. I just wanted to make it run for fun so I replaced loading belt and pickup (a KSS-240a) and it worked. I then decided to give it a clean so i took it apart and cleaned most of it to make it at least presentable. Upon reassembly it no longer works, the disc spindle start rotating in both direction and the lens is moved all the way up.

I checked with the finger on the BD board controlling the pick-up and an IC gets pretty hot within seconds. Referring to the attached image is the IC on the right, the driver for all the actuators (motors and coils). Is it toast ?

I checked all connections and everything looks fine; I tried several other KSS-240 and it always behaved the same regardless the pick-up was actually working or not. On the BD board there are very little components that can go wrong, no electrolytic's, no transistors, just two IC's, several resistors and ceramic caps. The pickup is entirely controlled by this board, the main board receives the PCM data already decoded and just instructs the BD board to play, stop pause and skip.

Very likely that IC is toast, I do not know how I did it, but this player has been heavily used.

Any idea ?
thanks

I posted this in a thread about repairing surrounds, but it's several years old, so I am posting here.
I am replacing the surrounds on some Scanspeak Revelator 7" mid/woofers & have a few questions. I plan to use the DC voltage or 50Hz sinewave method to help center the VC. The question is about the gluing process. These surrounds fit tightly into the rim of the frame with very, if any, wiggle room for final alignment. If I am very careful when gluing the cone would this lack of rim adjustability be a concern? On one hand I can see that this situation may benefit the accuracy of my initial gluing of the cone & on the other hand.... well it may make it more difficult. Any thoughts are appreciated.
Also: when using a regulated power supply what voltage should I set it to & should I worry about limiting the current? Power handling specs state: 100h RMS noise test = 60W & Long term Max Power = 70W
Also #2: Is the DC voltage as effective at aligning the VC or is it just a convenience for lifting the cone into position? Guess & could use both to offset the cone while still having it travel in the gap. My main concern tho, is the amount of DC to apply for the time it takes to complete the job.
Thanks,
Kev

Hello,

now I am here, after reading and enjoying the forums in the last couple of months 🙂
My name is Istvan (which means Steven), I am 53 years young, living in Vienna, Austria in the heart of Europe.
My main hobby is high end audio (really? 😀); until now I had some diy-projects (only amps) but most recently I finished my first speaker, the Frugal Horn MkIII.
I'm looking for a good exchange of experiences and ideas and for a good communication too. Regarding communication... I am by far not a native english speaker (really? 😀), so I am sorry for my mistakes in advance... but I'll try my best.

Best regards
Istvan

Hi,
I am struggling to understand the purpose of the 60 ohm resistor in this crossover:

I simulated it with "5 spice", I understand the purpose of the other elements, but this appears to reduce the attenuation of the woofer at high frequencies to just a few dB below the output of the tweeter? Is this for transient response? Doesn't it make one prone to hearing the effects of the cone break up?
thanks

(ps. This comes from Mark K's speaker pages: The Seas ER18DXT ported two way
Looks like an interesting 2 way)
tx

Hi Everyone,

Bit of a novice her, but enjoying trying to fix junk old amplifiers, especially with the helps from you guys.

I have a Scott A417, where the output & driver transitors are complete toast on one channel, together with a whole bunch or resistors in the near vicinity. Also all 4 diodes on the rectifier are burntout, so this amp is a complete basket case.

Taking this opportunity I intend to change all the transistors on the power board, caps & of course all burnt resistors. There are a couple of antiquated low power transistors 2SC374 & 2SA495, where I can't find any equivalent transistors referring to on-line sites for equivalence, I guess this is because of their body type (TO98-1), but really the form or shape of the transistor isn't important as they are all free standing off the board.

These transistors both have very low Vce & Vcb voltage ratings compared to modern available types & hFE of 40.

Question. I presume the key important parameter for their replacement is the amplification factor (hFE), so maintaining the same value of 40. Is this correct ?
Also practically would fitting transistors with (much) higher max voltage ratings & collector current be an issue, or is it better to try to find ones with similar ratings ?

Many thanks,

Hey everyone,

I'm interested in doing my first speaker build, and I'd like it to be a kit for use on my desk. I'm somewhat space limited, so I'm considering options in the Overnight Sensation size range - IE 6x9x8 and 4.5L ish for volume. Options I've identified so far:

• Overnight Sensations
• Carmody S2000
• Bagby Sopranos

The Sopranos look great, but I'm not sure it's wise to spend that much money on my first foray. I've looked at the parts-express C note, and I think they're just a little too large. So that brings it down the the OS and S2000 (unless I'm missing other options, which I'm all ears for). Anyone have opinions on one vs the other? I'd like to keep it around the $200 mark.

Thanks in advance.

-Adrian

Hi, I'm trying to repair a friend's cheap USB capable turntable. It's powered by a 14V wall wart and has a lot of SMD electronics inside it.



I found an apparent Schottky diode (SMD component with a cathode band marked as SS34, according to Vishay has a 40V max DC blocking voltage) with some odd behavior- I can measure single digit resistance across it in either direction using an ohmmeter. When the unit is receiving power from the wall wart I can't measure a potential difference across the diode, though I can measure about 14V from another, nearby diode. I tried shorting across the suspect diode with a normal 1N4004 diode but that didn't help (not surprising given it's acting like a wire on it's own).



My questions are 1) this is bad behavior for a Schottky diode, right? and 2) is there any reasonable circuit design that would have single-digit resistance in both directions in parallel with a Schottky diode? I have no schematic and wasn't able to find one online.


Trying to decide whether it's worth it to try and replace the Schottky or not. Thanks for reading!

Seems to have vanished from the members area?

Hello, I am new to this forum but reading already for quite some time interesting questions and answers.
Over the years I developed myself a nice audio system which I really enjoy (system components listed below). I did investigate what is the best option for me to improve my system and I think replacing the analog active filter I use by a DSP based system would be a nice next step. I want to move to DSP based crossover, phase correction, time alignment, room correction and have some questions related. I think PC software based DSP is the best way for me to go for.
I am planning to use Acourate for measurement and creating the filters.
At the moment I am using Roon and I did read Roon can handle these filters so that could be interesting for me. Otherwise JRiver is one of the best option as far as I understood.
I now try to make the right design decisions regarding the hardware and interfaces to use.
Question 1: I am thinking of using an fanless NUC with i5 or i7 and 8GB RAM. Any advice on this?
Question 2: I am planning to add 2 more Metrum DAC’s to my system to create a DSP based 3-way system. What is the best option to connect these DAC’s to the NUC? Use the USB port of the Metrum and connect 3 USB cables from NUC to the 3 Metrum DAC’s? I have the feeling this can generate timing (clock) problems. But is this more theoretical are also audible?
Or is it better to add an audio card to the NUC with for example 3x AES/EBU output. Or is it better to use something like “XMOS USB Digital Interface 32/384khz AES EBU” like the XMOS USB Digital Interface 32/384khz AES EBU TCXO Alimentation 230V Silver - Audiophonics or SINGXER SU-2 USB Digital Interface 32bit 768khz DSD1024 SPDIF AES/EBU I2S HDMI LVDS - Audiophonics ?
Or do you advice a different way to connect the DSP NUC to the DAC’s?

In short my current audio system:
• Magnepan MG20.1 (fully modified, silver foil wiring, no internal crossover, all external with high quality components)
• 2x Velodyne DD12 (I am not using the bass panel of the MG20.1 because it has a negative influence on the mid panel and tweeter. The 2x DD12 replaces the bass panels and using the internal DSP I already improved the low level frequency domain in combination with my room.)
• Metrum Ambre source
• Metrum Adagio DAC (volume control normally not used)
• Audio Research LS26 (modified with ODAM caps)
• Magnepan active analog filter (crossover between bass and mid/high)
• Krell KSA 300S (upgraded version) and Audio Research VS115 (I use 1 of both to power the MG20.1. The Krell is better in controlling the mid panel and the VS115 creates a nicer and bigger soundstage with the big ribbon tweeter)
• Interlinks Transparent Balanced reference and speaker wires self made using Mundorf 44mm foil and Teflon isolator.

Hello all,
My first post with a question🙂
I am looking for a amplifier with high input to power my DIY sub .
If possible no plate amp ,something like a Reckhorn sub amp.
This has (crossover) adjustment in it ( not wat I want).
There is no low output available (and is in my opinion not the way to go)
I am doing a diy crossover with high end components
Summery :I need a straight amp (500 watt at 2 ohm RMS) with high input and no correction .
Not a very common setup I know.
My search on the net for a amp like this has not produced a lot options.
Has anyone ever heard or seen an amp like this ?
Al input is Welkom.
Best regards Ron

Hi everyone, i hope you all doing well. Anyway I need advice here. Despite worst quality component & circuit design i purchased this kit mainly because the chip is authentic. This kit cost me less than $2, so why not?! Already i have removed most of the components & will heavily modify it. It had BC548 based gain stage or something like that for each channel and cheap 4.7uf electrolytic + 47Kohm carbon film resistor in series with non-inv input!😱 Tda7297 has a fixed gain of 32dB & i believe that's more than enough or maybe way too much for unclipped full output.
Anyway my question is about mute & st-by operation. The layout has no provision for 'low cost st-by & mute option', instead the manufacturer chose second option (without microprocessor, see attached schematics); 10k resistor + 10uf cap for each pin connected to +VCC. My concern is power on pop noise. Should i increase mute resistor/ capacitor value to increase the delay time to avoid noise ? 🙂 Btw for power supply i'm going to use 12v bridge type transformer, 18vDC max.

Anyone know where to buy good but fairly cheap dual SMPS supplies for Class-D amps in Europe?

Now that we almost get a fine for ordering anything in China, we need some good alternatives to eBay.

Need Dual voltage + 1x15V + 1x12V

There is of course Hypex, but wouldn't mind somethin a bit lower priced per Watt

Thanks, Baldin

Yesterday I did an experiment that some of you might find interesting. I had been noticing bright, shrill sound from downloaded audio files and, in order to eliminate the incompetence of the person doing the original encoding, I dug out some DVD players from storage that are capable of making copies of SACD discs.

First attempt was with my Oppo BDP-103D and I used Sting's Sacred Love SACD as the original material. I copied an ISO of the whole disc via wireless LAN to my PC using SACDExtract, then converted to DFF stereo with ISO2DSD. Playback chain is PC -> Wi-fi -> Oppo UDP-103 -> Victor JM-S7 VFET -> Jordan J6T linear arrays.

Result: 5/10 Dry, bright, flat soundstage , no air.


Second attempt employed the Oppo BDP-105D using the same procedure.

Result: 7/10 Dry, less bright, more detail, no air.


Third attempt was using the BDP-105D ISO but converted to multi-channel.

Result: 8.5/10 More detail again, starting to sound normal.


Final test was to put the original disc in my UDP-2013 and play it.

Result: Huge soundstage, sweet, open, details for miles.


Conclusion: If you're serious about listening to music, don't download stuff off the internet. I just performed a BEST CASE assessment using the highest quality player capable of ripping SACD and lost 15% in the process. The average person uses equipment at BDP-103 level or lower quality, which just sucks the life out of the music completely.

And if you don't believe that digital information is changed in the process of copying it, I challenge you to make a copy of an HDCD disc and see if it lights the HDCD indicator on your player. I tried three discs downloaded off torrents, and none of them were HDCD any longer.

If so, and if yours is a recent model (the serial number of mine is D2S-09195, which I believe is 3-4 years old), then I have a favor to ask.

Would you be willing to open it up and take a couple pics for me? One straight-on shot of each side of the pc board is needed.

I will soon be doing an article detaling thorough modifications to make this amp sound good. But I forgot to take photos of both sides of the pcb before starting! Argh! These pics are absolutely necessary for identifying and locating components.

Any help would be greatly appreciated. Either PM me or post them here.

I want to make a SMPS of around 2400 to 1800 W that is lower noise and EMI and more efficient than the usual.
I started a "3 phase" thread but 3 phase is not widely available and that limited the interest.
Since my preferred option is to build the three phase system out of a series of one phase modules anyway, I decided to start this thread dedicated to just the standard one phase SMPS component, usable by anybody.

For modules of around 800 W the basic default is usually a rectifier, boost PFC, bulk capacitor, then switcher for isolation and step down, then more rectification.
These days the switcher is often an LLC to enable it to soft switch.
That all works OK but is less efficient than possible because the multiple conversion steps all add losses.
A better option seems to be to combine the PFC and switcher, and maybe eliminate the separate input rectifiers too.
There's a lot of ways to do this and I have read many but can't find much of an overview or principles to choose between the options.
Some of the issues are

• Overall efficiency
• Control
  . Can a standard IC controller be used?
  . Duty cycle versus variable frequency etc.
• Control behaviour
  . Buck has simple response, many others have RHP zero that complicates feedback
• Stress on the transistors
  . Some circuits stress the transistors more severely with peak current or over volt transients at turn off/on.
• Ripple on the output.
  . Cuk looks nice here
• EMI coupled to the input
  . Cuk also nice here
• Soft-start
  . Easier with some circuits
• Circuit simplicity.
  . Obviously prefer simplicity, what's the trade-off?
• DCM/BCM/CCM
  . Optimisation of current mode.

Anyone tried to build an advanced circuit with better efficiency and lower noise?

David

I just read over this (while I was reading whatever somethings 🙂 )

Why would one want to cripple an F4?