Dears,
I am trying to repair this beauty from longer time, in vain.
Main problem is negative voltage close to negative rail on most of the transistors.
The voltages are close like on attached printscr, R30 is added only for simulating such situation, please delete it for LTSpice sims, and connect opt Q12,13.
I desoldered all of the transistors (opt are desoldered as in the sch), checked them, and were OK, I even soldered new ones, in vain.
Please ignore complicated nfb nest, this is just the simplification of Gm selector, it is messy but works for the simulation.
This is how it looks more or less in reality:
I attach also asc file,
Please give a hint what more should I check,
and thank you in advance
regards
Pawel

Hello,

i wanna finally dive into subwoofers and wanna build my first pair

i probably will still be using studio monitors for a while as main speakers, studio subwoofer and some diy subwoofer pair quite nice with studio monitors because they include a crossover to implement the subwoofer

i was looking at the Crown XTI series, probably my best bet if i wanna have an external amp where i can easly implement subwoofers in my setup

but i was wondering... are there any alternatives? specially class AB would intrique me, i basicly need an amp with an lowpass... and preferably XLR passtrough

Thanks in advance

243 Volt well regulated.
Around 40 mA output with very little ripple ~10uV.
More or less current is possible.

Not much to say.
Uses 2 Transformers to create 260 Volt input.
Two MOSFETs to make the regulation.

Hi,
Im a DIYer looking to build a power supply for my first DIY DAC (Miro's AD1862).
As far as I have researched, people usually recommend Nichicon UFG UKZ and Elna Silmic II for Electrolytic Caps. However, they have been discontinued. What is the next best alternative for them (or something better).

My neighbor asked me if I could take a look at his receiver for him. I don’t know how on earth he did this, but he said he accidentally shorted the neutral and the hot while plugging it in. Not sure how…

Anyways, it’s completely dead, no activity whatsoever. My first thought is the standby circuitry since it won’t even go into standby. I don’t have a schematic, nor am I able to find a schematic.

Here is the receiver


I checked all of the fuses I could find and all measure good. There are two on a board mounted to the bottom board which will be an absolute pain to remove, but could reach the fuses with my meter probes.

The other fuse is on this small side mounted board which I’m assuming is the standby board (don’t work on too many items this new).



I checked the diodes and such in circuit as well as some voltages.

There is a smd bridge rectifier on the back of the board. It’s the larger of the devices.


I’m measuring line voltage across the AC pins, about 123 vac. No voltage on the + or - pins which seems like it would be an issue, but using the diode mode on my meter the rectifier checks out while in circuit. Should I swap it out anyways?

Anyone with experience in standby circuits, any other recommendations as to what to check? Anyone have a schematic? I’ll remove the rectifier from the circuit to test, but any other suggestions would be great!

Thank you,
Dan

I have n arcam 8R amp that is stuck on max volume even if i turn the volume knob down it still on max.
What would be the first thing you would look at?

I have three of them so I can swap parts.


Thanks

Hi,

I currently have a DIRAC (MiniDSP SHD) 2.2 system (subs are SVS 3000 Micro).

Please take a look at my rough floor-plan, open-plan, glass and openings everywhere, one speaker in a corner the other next to the opening going to the dining room. The 5.4 x 5.8m living room has a cathedral ceiling, wooden floors throughout.

The subs and correction really help with the room. I should mention that room treatments are out of the question and the speaker placement can't change.

So if I was to replace my speakers (MTM TL floorstanders with 5" woofers and ribbon tweeters, which I think are probably overkill now I have the subs) with DIY active (CamillaDSP with DAC8X 8-ch DAC), what should I be thinking about, line array?

Thanks.

I am a sound engineer. I have very little knowledge but some little success building speakers - designs usually found online. I’m building these speakers because comparably specified “branded” studio monitors cost 3X as much as my build. As is, being only moderately successful in third world India, it has taken me a long time to save up and procure components for this current build.

“It's better to ask for forgiveness than permission” - Grace Hopper.

Every time I seek advice on driver selection and such, I get well meaning but strong, contrasting an opinions. I end up getting confused and doing nothing. This time, following my gut, for better or worse, I went ahead and bought the following drivers (per speaker):

Subwoofer - SB Acoustics SB Acoustics SB42FHCL75-6
Woofer - Purifi PTT8.0X04
Mid-Range - Volt VM752
Tweeter - Satori TW29RN-4

Four way design powered by QSC PLD 4.2 - 4x 400W w/ onboard DSP

The listening position will be a mere 5’ from the speakers. Most of the space between the speakers and listener will be occupied by a console table.I know this could be a problem… positioning large speakers in the near-field position… but there are plenty of reputed 3 way near-field monitors, mine just add the subs. My room is very highly damped, down to about 40 Hz…

I’ve come up with two cabinet layout designs, I seek your opinions on these, and suggestions for alternatives.



Option 1: Woofer to the side of mid-range/tweeter

Advantages:
A. Driver to driver proximity should lead to a more cohesive sound?...
B. More space for subwoofer cabinet (3-way "satellite" speakers will be in a separate enclosure, placed on top of the subwoofer).

Disadvantage: path length differences will significantly affect integrity in the horizontal plane?

Option 2: Woofer below mid-range/tweeter.

Advantage: Better Integrity in the horizontal plane?

Disadvantages:

A. Woofer lip is just above the console table top, possibly leading to a reflected, comb filtered sound dominating the direct sound.
B. Less space for the subwoofer enclosure.
C. Too much driver to driver distance?

Looking forward to inputs. Thank you.

For sale fully functional XCCS BOSOZ. Output caps Mundorf Evo Supreme Oil.

Extract from Mr Ohashi's Blog June 30 2024
Power Amp with Hashimoto HW40... P1616D
Translated By Google Translation.



You will notice that the output transformer has been replaced by Hashimoto HW-40. It is still in the evaluation stage, but if there are no problems electrically or in terms of sound quality, it will be exported to Canada/USA.

It would be premature to think that anyone can just change the OPT... The output transformer affects the overall characteristics as much as a car engine. In cases such as a single triode with no feedback, it may be possible to replace it by checking the impedance and core capacity, but in the case of a push-pull amplifier with a large amount of feedback, in the worst case scenario, the amplifier may oscillate and be damaged, so careful consideration in advance and detailed measurements after replacement are required.

The original output transformer is a custom-made product (made in Japan) optimized for the SV-P1616D and has KNF (cathode NF) windings, but the OPT to be installed this time does not have KNF windings. NFB is established based on the delicate balance of the amplifier, so the design is very delicate and design changes are required.

According to the report of the craftsman who was commissioned to make the prototype, the default NF resistor and phase compensation capacitor capacitance caused oscillation outside the audible range. This is something that cannot be detected by ear and can only be detected by measurement, so special care is required. As a result, integral compensation was added to the secondary side of the OPT to ensure stability and the project was completed.


These are the frequency and phase characteristics of the EL34 model with integral compensation and Hashimoto OPT. The results are impressive: gain 29dB/8Ω, output 40W+40W, frequency response 10Hz~160kHz/-3dB. With KT170, the output will increase by about 15%~20%. If you convert it to a MONO BLOCK and make it a parallel PP, as I wrote in my previous entry, an output of close to 100W will become a reality.

https://www.diyaudio.com/community/threads/double-the-output-power-of-set-amp.412884/

Thought I better have a bit of a clear out. I realise as much as I like these small class A amps that my speakers are a bit more demanding.
Built with my own clone boards done by Prasi.
All working nicely, was set up at 24v.

£65 plus shipping.

Hello all!

I have found a few schematics based on L6599AD chip.

I am wondering if there is simulation model available and how to simulate SMPS.

I then want to create schematics and PCB layout for few different power outputs and post them for everyone to access.

Any help is appreciated.

Original XRK pcb - 35€/set


All Cee’s (built and ready) - 50€/set


SSR protect by LKA (built and ready) - 30€/set


SoftStart by LKA (built and ready) ((incl. dc protect, lc filter, over temp, remote master/slave)) - 60€


If anyone is interested I also have a 4U/300 modushop box with predrilled holes for boards. (incl. engraved front panel) - 100€

Payment via PayPal. I ship modules and PCBs worldwide, box only within EU.

Hi gents,
Having trouble with the speakers being overly bright , when I received the Speakers the crossovers were external because a previous owner had made them active ( kept the original crossovers )
I have since fitted the original passive crossovers internally as per originals, I wired them identically as when they were external ( photos taken before)
But now I’m told that the tweeter should be wired out of phase according to the schematic , can someone confirm if any of the drivers should be wired in reverse polarity please?

I found some pictures of B139 transmission line systems.

The first picture shows Roger's Monitor MKII on the outside and Atkins State of the Art in the middle.

The second picture is the Roger's monitor under construction.

Looking for a pair of drivers TAD TD-2001 for a new project.
If you have a pair in perfect conditions please let me know 🙂

Thank you

Good day to all. I just joined this forum this morning. I am always on the hunt for more A/V information and find forums such as this are usually a better place to obtain that information than most magazines devoted to the subject. As an A/V enthusiast for more than 50 years and one who is closer to the age of 70 than 60, I have seen technology go from a 12" black and white TV to today's amazing 100"+ displays that deliver stunning images. Have also seen and heard audio from a tinny sounding record player the size of a small suitcase (my first recorded music playback device - which was a major step up from my hand-held transistor radio) to today's astonishing options to get your music fix.
I look forward to learning from all of you.

Having discovered Sonarworks SoundID Reference for Speakers recently, I had to find out that this Speaker/Room adaptation software only provides filter settings compatible to a handfull of specific speakers and DAWs. This is unfortunate as the User Interface and wizzard steering is sooo much better than Acourate and the results comparable at a comparable license price.

Which alternatives to Acourate and Sonarworks can you recommend which are as easy to use as Sonarworks and which put out miniDSP openDRC compatible parameter files?


I just hope there's something out there I'm not aware of yet.
Thanks a lot!
Winfried

Hi,

Please can you help explain to a beginner how this design makes sense?

So up front is a 5" coaxial with a 1" dome, so basically a Q150 driver?

Four 9" woofers, so the guts of two KC92's?

It's high-density polyurethane, so thick plastic, there doesn't look like much air volume in that cabinet?

So these things are wired like normal speakers, they're not active, how does those subs work properly without a DSP?

Could I essentially get the same sound by buying four KC92's and a pair of Q150's, so a total of AUD$15K RRP and hooking them up to a DSP, with room correction, in a standard living room, it could possibly sound better than these AUD$60K speakers?

Is a coaxial with a curved baffle and loads of subs the Nirvana then?

I might head to the workshop at have a go at replicating this speaker shape in plywood with the CNC.

Thanks.

I have 40 NOS pieces Siemens D3A tubes in original boxes, I intend to sell a lots of 4 tubes for €120 but if you want more let me know. The price does not include shipping costs. PayPal accepted, plus 5% PayPal fees. With PayPal Friend, the 5% does not apply.

Sold

I would like someone to explain how speaker impendence affects the amplifier. I know amplifier have a impedence rating and you're not supposed to go below that because it will draw too much current from the transistor.

How is that speaker impendence measured though? For example, I have a two way speaker system here whose impedence dips to 3.1 ohm. If I build the XO the way I want to it will dip down to 2.1 ohm. We all know a speaker doesn't just play one tone. It plays a spectrum of music at the same time. So, if it is playing a bass tone at 12 ohm and a high frequency tone at 3.1 tone at the same time, will it place an average impendence on the amplifier of 9 ohm? This is what I do not understand and I would like someone to explain to me.

I am an electrical engineer (slash manufacturing engineer) but I honestly do not really understand class D amplifiers. That is half the reason I got into this hobby. I like things I don't understand.

Thank you in advance for your response.

[NOTE: This is a draft design in work and has not been fully tested with the new bushing design. The original design can be found here and has been confirmed to work. This new design will get additional info added once a couple early adopters confirm it works.]

This is a mount for the standard Alps RK27 volume potentiometer to be able to mount it remotely away from the front panel, minimizing wire length to the Iron Pre SE board. The height of the design is currently configured for the Iron Pre SE chassis from Modushop to align with the 8mm bore hole on the front plate (40mm center-line off bottom chassis plate). This version should be an improvement from my original design, which required more parts, including a roller blade style bearing and two different tubes. The new version requires just one tube and uses a 3D printed part as a bearing.

It mounts with two M3 bolts from the bottom and they screw directly into the plastic. There are slots if you want to add M3 nuts for added security (however, not needed with a long enough M3 bolt). The Alps Pot fits very snugly into the mount, so don't press it all the way in until you know you won't be taking it out. It can still be removed with some force, however, just avoid pushing it all the way in until you're ready to connect the extension rod. This works just fine with the Pete Millet Alps Pot PCB.

A small 3D printed bushing is also part of the "kit" to allow a 6mm OD tube (or solid rod) to be centered in place and allow rotation of the external knob with no play. A little drop of machine oil will help create a smooth rotation.

Two additional pieces of hardware are needed. A 6mm OD tube, or solid rod (aluminum or steel) [200mm or longer] and a 6mm to 6mm coupler, both which can be found at Bezos's bookstore.




I'm willing to provide a kit at my cost + shipping if you don't have a 3D printer. However, for those folks with a 3D printer, this is a fun way to do a little more DIY vs buying something on Aliexpress. [Search for "Alps RK27 extension" to find those options]

Files attached in Zip file below are 3MF files. If you need STL files (or others), please ask.

Hello friend,
I offer for sale this set LKA softstart + LKA Amp PCB + small heatsinks

Transformers for this amp: https://www.diyaudio.com/community/threads/audio-grade-transformers.417582/#post-7789808

Price for set: 60€
Payment PayPal

I own some vintage McIntosh amps that I need fully restored and capped. I have an MA-5100, MC-2300,MC-2500, C-28, and a MAC- 4100 receiver.
I believe I’m in dire need of a good restoration and recapping of my amplifiers, meaning getting the highest quality caps and innards. Currently I’m running on the old silver General Electric big filter caps in mine at present, but I’m getting some scratching, leaky odors, and even humming in the 2300 and tha MA-5100. I’ve heard of brand names such as Elna, Nichicon/Panasonic, IC, Chem Con, and Mepco/Electra.
If anyone who has knowledge of these brands of parts, please let me know. Thanx very much.

Im repairing a Kicker CXA660.5 and I wanted to know what parts (FETs or push/pulls) are used for Q15/16 and Q501 and 502. I could not read the part numbers due to burn damage and I ordered some N channel FETs to try in it based on another Kicker amp I had but they are not working, Im getting very high current pulling and heat from the Q501/Q502 now. I assume I just got the wrong parts. The amp turned on before the repairs and the AB front/rear channels all work even though the protect light was on. I just needed to know the parts or if possible the type of parts (N or P channel FETs, or AB push/pull transistors NPN/PNP and the parameters that need to be met.

I’m totally confused (as usual) 🙈

I have been a car audio installer for 10+ years looking to learn more about horns hlcd.

I have 4 of these and considering selling 2-4 of them if at a good price.

Just curious if i can sell these for $500AUD each or 950 for a pair. Note these are located in Australia, can ship interstate for an additional cost. To get them new now in Australia would cost close to double.

These are a custom version with the phase plug.

175g instead of 250g mms.
93Db instead 90Db sensitivity.
0.48 qes and 4.8 qms

T/S parameters are here:
https://www.stereo.net.au/forums/up...d(1).png.eec824a98d9b1593d364b78f1e0ece70.png

New member here. Thought I had introduced myself, but I had only posted a profile...
Joined for a chance at Bohlender-Graebener ribbons.

Wish me luck!

LA in CA
ecc83tfk

Not sure if I qualify for diyAudio, but I've been using a MySqueezebox radio since 2011. I noticed that the back of the radio has an Ethernet port. I was looking for help to use it, sort of, but I think that's a little over my head. After seeing that the MySqueezebox site had been taken down, I was looking for tips on how to use what I have. I would be happy if I could get Pandora or other streaming radio. Of course, a recommendation for an alternative radio would be welcome.

I am able to use the Squeezebox at home accessing it over the home network.

Hope that gives you some background.

Dear all,

I would like to start building my own RH84 tube amp. Is there any online webshop that covers all or most of the parts required for that?

European and international shipping are acceptable.

Not very sure if a recommendation for dealer by replying to this post is allowed, so please PM me if is good for you.

Thank you.

Best,

Here is Otaru...


Mr Kazutoshi Tsukahara


Mr Makoto Ohashi's 100+ years house




FUKUOKA- Nakasu

I am interested in building the Scan Speak Discovery 861 speakers but need the crossover values for the capacitors, inductors, and resistors. Anybody willing to share this data? I can buy the speaker drivers from US suppliers, but need the cross over data. I dont want to have to pay for overseas shipping and custom's fees for buying the full kit from Jantzen Audio. Thanks for your help.

For sale are the newest burson opamps, V7 Vivid dual. Two pieces. Price 110€ + shipping fees, paypal F&F. Classics fit my system better, so Vivids are up for grabs.

Hi folks

I own an APx525 ( first gen, SW 4.6 ) and for years, I wanted to have a discussion about pros/cons/tips and tricks for this unit,
I know, tomchr had one ( now on APx555, I think ). Any other APx users out there ? Should we open a dedicated thread
about APx machines ( not AP 2xxx, cause of the total different GUI, sorry ) ?
Also, if one prefers to have a private conversation, would be fine, too.

Greetings from Vienna

Gary

I have had this great sounding QED CD240 amp for decades. Over the years it's had several sets of BD911/912 replacement output devices and a few other small driver components.
About 3 years ago it suddenly stopped working after a period of running quite hot to the touch.
I then changed the bridge rectifier and it worked fine until recently when it started playing up by taking progressively longer to start working
after switching it back on. Even now, once it starts after 15 minutes and if I don't switch it off it works fine until I switch it off. Any ideas anyone? Thanks

Questions about RF chokes used in McIntosh tube amps.

Since 1960 production, McIntosh MC240 and MC275 have used RF choke 1.5uH and 2.7uH that

1. connects KT88’s plate to transformer primary plate out - this is understandable to avoid high frequency oscillation.

2. connects upper KT88’s screen to lower KT88’s plate? And another choke to connect upper KT88’s plate to lower KT88’s screen? Why is that?

3. Why two different choke values? Aren’t push pull supposed to be symmetric at high frequency cut off?

Good evening.
I planned on getting out of this hobby, mostly due to lack of time for building and learning.

So, I thought "why not make a pre amp and a simple power amp and leave it at that?".

I decade or two ago I build Greg Balls GB150 and for some reason I sold it.

I managed to find old kits for 4x channels and thought that this will take no time at all.

The PSU is ok but fuses are blowing when I connect the power amp PCBs.

I thought that there must be a short somewhere and measured resistance between the positive and negative rail on the PCBs (PSU disconnected) and found it to be just above 1R.

So, does anyone remember these old amps?

I have attached the schematic which should be mostly correct anyway.

Hopefully someone can assist me with some troubleshooting, I kind of realized that I should do something I actually can learn instead but I want to finish this 🙂

Hi, What are these 2 components connected to the Cathode / Ground of the 12AT7 tube. Also, what would be their purpose/function? This tube is the 2nd tube in the phono stage. 12AT7 --> 12AT7 --> line stage

Thanks

Interlude Audio launched earlier this year with the release of an Analog HAT and we’re now ready to launch our Digital HAT.

We’re compatible with RPi 3, 4, and 5 and support auto config, which means there’s no tweaking the config.txt file. Our drivers are integrated with the Raspberry Pi OS, we have support for Volumio, and we’ve built our own Busker OS based on the Raspberry Pi OS, which includes support for Spotify, Airplay, and Roon.

Analog HAT
The Interlude Audio Analog HAT offers a high quality power circuit which ensures exceptional DAC/ADC performance. This sophisticated design includes a meticulously crafted power tree, providing clean, stable power to all parts of the circuit, and effectively isolates noise. We include a 12V power supply which powers both the HAT and the RPi.

Utilizing the CS4272 featuring wide dynamic range, negligible distortion, and low noise, our Analog HAT achieves an SNR of 105.7dB, dynamic range of 103.9dB, and SINAD measured at 94.9dB.


Digital HAT
Based on the WM8805, to reduce jitter and maintain signal integrity, the Interlude Audio Digital HAT provides both coax and optical input and output. Furthermore, our dual oscillator design guarantees zero jitter across all sample rates.

The Digital HAT stands out in its ability to handle a wide range of sample rates, making it a versatile choice for high-resolution audio playback. We’ve made monitoring the sample rate of your audio simple by including LEDs which indicate the current sample rate in kHz: 44.1, 88.2, 176.4, 48, 96, and 192.



Please visit our website for more information: interludeaudio.com

Well, I am putting Greg Balls GB150 together and for some reason thought it a good idea to try one of those Chinese smps.

I got one 300W with +48 0 -48 secondaries and the regular L-PE-N primary.

I added a 2A slow blow and it keeps blowing at startup. Even with the amplifier disconnected.

Am I missing something?

Just completed V2 of the fully active, zero/open baffle units.
Login to view embedded media

which driver sounds the best.. I want dry..
https://www.eighteensound.it/media/W1siZiIsIjIwMjMvMDcvMTcvMTRfMDVfNTlfMzA3XzE4U3ViX3YxXzEucGRmIl1d

it should work well with this..
https://www.eighteensound.it/media/...dfNzcxXzE4X1NvdW5kXzEyXzJfV2F5c192MS5wZGYiXV0

I'm thinking of building passive crossovers for tops and subs..

/anders

Hi ! i am testing caps i have at hand with this meter


some caps rated 22mF measure around 17mF
i wonder if i can still use them without issues
Other NOS caps instead measure accordingly with their rating
Moreover i would like to understand if there is a cheap but reliable way to check the ESR
I have seen only a very expensive meter
Thank you all sincerely

I bought a defective DALI SWA 15 subwoofer and the builtin Class D amplifier is not amplifying (can hear very low signal), i had contact with hifiklubben (the reseller in Sweden) so they could contact dali but they dont give out the servicemanuals to endcustomers.
Is there anyone here that can manage to get a hold of one or mabye point in a possible direction that what could be wrong ?

The fuses was blown (all 3) so the mosfets and 2 controller ic's is now replaced by a very experienced repairman.
But now he has come out of ideas. Apparently the transformer has a big load and he cant get it to be normal.

I have built a movieroom on the second floor of my garage and are experimenting on how to get a versatile soundsetup.

Reciever : Nad 758v3
Amplifiers : 1 Crown XLS 2502, 2 Crown XLS 1002 and one CewinVega 2.6kW
Front speakers : 2 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer in moviemode and 2 CerwinVega Clsc215 for partymode
Center : 1 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer
Sidepeakers : 2 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer
Rearspeakers : 2 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer
Front cornersubs : 2 homebuilt ported boxes recessed in the walls with Dayton Ultimax UM18 tuned to 20Hz
Rear cornersubs : 2 homebuilt ported boxes recessed in the walls with PA 18" tuned to 30Hz
Subcontroller : MiniDSP 2x4HD and Umic1
Visual : Philips The one 75" screen
Speakermeasurements : Dayton Dats v3

Fostex FE206NV project is finished.
Some ML-TL derived from a Martin King project for Lowther that with some modifications fit into the TS parameters of the Fostex, these being very similar to those of the Lowther Dx2.
http://www.quarter-wave.com/Project04/Project04.html

To equalize this extended range I decided on two notch filters centered at 2.6k and 9k and a step speaker that starts at 150 hrz.
It has a rise of about 5 dB above 10k, very suitable for those of us who have lost sensitivity in those highs.
The impedance was very friendly for the tube amplifier with which this system will be used.

Note: Hornresp was used for the design and simulation of the box. Jeff Bagby's spreadsheet and XSim were used to design and simulate the filters. For response measurements the REW and for impedance the LIMP. All software free to use. It was measured with a Dayton IMM6 calibrated microphone.
Sorry for my english

Hi,

I have made PCB layout in Eagle 6.5 for DOGC-H amplifier designed by Dr. Borivoje Jagodic.

PCB is not tested yet, so any improvement suggestions are welcomed.

Hi ! sorry if the question sounds confused
I still think that a low THD is a good think to get
I was reading a review online and i found these graphs
https://www.audiosciencereview.com/...ds/revel-m106-bookshelf-speaker-review.14363/
considering the graph on the right i have the feeling that using this speaker full range could be a very bad idea
Anyway i wonder if i had to use a high pass filter on this speaker what would be the best crossover point
I mean how much THD can be tolerated ?
What is missing is a IMD graph
I am sure that exciting this speaker with powerful 100Hz signals would be devastating for the overall performance

https://www.diyaudio.com/forums/attachments/solid-state/1001999d1638447744-cfh7-amp-cfh11_1v2_sch-pdfFollowing the naming convention for amps used in this thread and also first posted here, I am starting a new thread as this is not anything like an Apex design offshoot anymore:

100W Ultimate Fidelity Amplifier - Page 820 - diyAudio

However, I think I will keep the standard naming convention that Apex Audio likes to use. So CFH7 stands for Current feedback HexFET with 7 active components. The amp arose out of the surprisingly successful FH9 and FH11/12 amp designs from the same thread, but with a current feedback topology that I believe was first used by Gaborbela as described here:

My first DIY amplifier 20 years a go - diyAudio



This same topology is also used in the very popular VSSA series of amps (VSSA, PeeCeeBee, FET-hex explendit, etc). My biggest inspiration for using the Gaborbela topology came after I built the amp described here:

VSSA Through-Hole Version by Jason - Page 86 - diyAudio

Now, I have applied the Gaborbela topology with the great sounding, popular and cost-effective IRFP240/9240 hexFETs, while reducing the number of active component parts count from the FH9, which has 9, to 7 transistors by elimination of two transistor CCS's. The simulations of this amp in TINA indicate a surprisingly good level of performance. The usual BD139 is still used for temperature compensation as a Vbe multiplier. Very large 4700uF rail caps are needed if you want the squarest square waves, but smaller 1000uF caps would probably sound just fine.

Here is the schematic:



And here are the simulated results:

1kHz sine wave at 50v p-p with 80mA quiescent bias current:


50kHz square wave:


200kHz square wave:


FFT spectrum at 1kHz:


HD components at 1kHz sine wave excitation:


HD components at 20kHz sine wave excitation:


Gain and Phase as a function of frequency:


As you can see, the predicted HD of 0.00084% at 1kHz and the clean, sharp-edged square waves are very good indeed for a 7 active element amp that uses nothing exotic or special. Vishay hexFETs are available for under $1/ea, so this amp is literally under $5 to build. The bang for the buck on this amp is pretty much up there.

So, it's still in simulated schematic stage at this point and un-tested. I would welcome someone taking a crack at the layout for a Sprint/Gerber file and we can then test and listen.

Edit Aug 3, 2016: several members have pointed out that this topology probably originated from Japan in the 1970's:







Version 1.1 schematic that Idefix will design layout for:


Update Aug. 7, 2016: Idefixes generated the new layout (with associated schematic for parts numbering):



We are going to press with this layout - a masterpiece - great work Idefixes!


BOM for above amp:

http://www.diyaudio.com/forums/attachments/solid-state/572548d1475477936-cfh7-amp-cfh7-bom.txt

Edit: Aug 15, 2016 - Sonal Kunal has just developed a single sided layout - still not final but very cool looking.



Edit: Aug. 16, 2106 - Latest layout from Sonal with no onboard inductor but 100mm max size


Edit: Aug. 17, 2016 - Idefixes has a beautiful new 2-layer layout that re-routes the ground bus to reduce RF spray onto the input stage:


So many layouts to try!

Still4given or Andrewlebon will probably be the first to reach first sound.

Andrewlebon in progress...


Still4given in progress...


I can't wait to see someone with a small waisted F1 car style board as Sonal has prescribed.

Edit Aug 19, 2016: Still4given had built and verified that Sonal's layout works but requires fixing wiring of Vbe multiplier as that has an error and also 4.7R gate stoppers are not enough to prevent oscillation. 100R seems to work there.

CFH7 Amp - Page 21 - diyAudio



Here is a dual output pair version called CFH9:


CFH9 works well - nice square wave:


CFH9 in stereo with Juma's Easy Peasy cap multiplier:


This is one of my top 3 amps.


Dec 16, 2016: Thanks to Thimios for finding grounding issue in design. Here is final mod to achieve very good PSRR and low THD. See post here

http://www.diyaudio.com/forums/solid-state/294834-cfh7-amp-82.html#post4920073



Edit Dec 5, 2021: saddevil has made a nice layout with some improvements in a cap Mx for the front end and one for the main outputs. This should have a really low noise background.


More info and Gerbers, here. Schematics here.

I have seen where someone has added a 12v relay for switching to the mc103, but I would like to put a module in that automatically switches to the active source. I know my Fosi v3 monoblocks have that feature built in and I think it would be nice to integrate jnto mine.

What do they call a board that does this, and what do I need to look for in one when I find one?

Did anyone else stupidly not properly save their months and months worth of adding items to their basket, only to lose it all when the Mouser site had some issues last week.!
Bugger.
Lesson learned!

Hello,

All This is Raghu from Hyderabad INDIA iam interested in discussion of Audio and Video.

Thanks
Raghu

Hi
I have technics sl-pg200a, bought it just to take cdm4/19 out of it. Also bought used Philips monokit board based on saa7310 and zc99696p which I thought should be better than mn6626 (which is used in technics). But after testing the Philips board with the mechanism I noticed that seeking between tracks is much slower than in technics and also a bit noisier. Is that normal behaviour or should I look for some issues on that board?

So I’m looking for a tweeter to replace my initial design for a large high power 3-way studio monitor main.
The bass is a 12” Fane pro driver.
The midrange is also a Fane; 5” studio.
Initially I planned to use a Fane 1” compression driver in a small waveguide but
A) I’m unable to source the Fane CDs anywhere but in UK which would amplify the cost dramatically, and
B) I cannot find a waveguide small enough and still rugged enough to fit the baffle and carry the weight of a solid CD.
My backup option is to use a leftover Eminence APT50 but I don’t like the plastic horn, I’d prefer something aluminum and I’m unsure about its performance.
Also it is a tad to big.
So I’m considering a plan C then; a traditional tweeter of small footprint.
But I have some requirements:

• no bigger than 7cm diameter, preferably a neo magnet
• metal grill for protection
• slightly hornloaded is preferred to control the directivity and boost the sensitivity
• high power high sensitivity from 3kHz
• proven vendor, spare parts/replaceability
• sweet sound but details are more important / honest revealing
• no plastic chassis
• easy mounting cutout
• cheap

Any ideas?

Sold

Hi

I hope someone can help me in my search for a very specific part - or maybe advise an alternative way to achieve the same with other means.
So, in short I am looking for a potentiometer with a center detent - but would like to have one that is spring loaded in both directions.
Meaning that if I turn to one side and release it I want it to snap back to the center detent. Naturally the same for the other side as well.
I have searched a lot but have not been able to find anything except spring loaded switches. But that is not what I am searching for.
Thinking old motorized tuners would use something like that.
Alternatively, if there is an easy way to create/attach a spring load mechanism - but remember working both directions then that would potentially
be even better if I that way was also able to adjust how strong the springs could be.
Hope someone has a great idea.

Thanks

https://audioxpress.com/news/ess-te...igh-performance-8-channel-ess-sabre-smart-dac



dave

I was offered a Sae A205 amp, there is not much info out there, plenty of power, looks like a Acurus or Adcom mosfet amp.
but I am not sure.

Is this a Mosfet amp ?
what are the bias number without a service manual ?
Is the design any good ?

100wpc Class A/200wpc Class AB1.
4x Toshiba 2SA1302, 4 x 2SC3281 each side

thanks for your help

Is there someone who can explain this further and even have experience:

https://lyngdorf.steinwaylyngdorf.com/lyngdorf-ls-1000/

I can see that the tweeter is slightly angeled. But Lyngdorf say this:

The Lyngdorf LS-1000 Left has a sound dispersion slightly beaming inwards when placed on the left side, away from the side wall and towards the listening area.

The Lyngdorf LS-1000 Right has a sound dispersion slightly beaming inwards when placed on the right side, away from the side wall and towards the listening area.


I have been explained that f ex JBL 4435 have this feature for high placement in studios.

I ask because i am interested to make a similar inwall line source whitout physical toe-in

Am originally power supply designer. Good for resolving power supply issue for amp.

New member here, this is my introductory post.

I started my audio journey restoring valve radios, moving onwards to building valve amplifiers and the occasional solid state build.

I enjoy the building as much as I do the listening.

Looking forward to contributing and learning from this community

Gabriel

Got an old Denon CD player which I terminated but not before doing some tests. Besides SM5840 and 2 x PCM61 it had the often found dual tracking regulator M5290P. It came to my eye that this regulator is pretty silent.

Never thought about that. This is a regulator of at least 25 years ago. Check that datasheet!

Hello,

I have an amplifier Marantz-95 equivalent to Philips DFA 1000 which needs to be serviced.
For doinfg so I need the corresponding service manual.
Any input to get it will be welcomed.

Thanks a lot


Alain

Marantz PM-95 Specifications Marantz

Hello,
During my internet travels I bumped into this guy. I wonder if anyone here is familiar?

https://kaamostech.com/

Guitar players spend years to find the right mix of 2 or even 4 speakers in their cab.... Like a cook blending spices.

I was looking at compression drivers and suddenly thought "what about mixing 2 or even 4 different ones on one horn (with a manifold). Obviously ones with similar sensitivity and impedance....

My rationale is: Every driver has different artifacts, resonances, diffracions and breakup modes.

A single driver that has a +2 db spike somewhere along the frequency plot would only show up as a 0.5db hump in the combined output of 4 different drivers. Also it would be interesting how a titanium and phenolic driver sound together on a single horn.

Is this a silly idea?
Has it been done before?
Are there any obvious negatives?

I am interested to hear what others think of this.

Im trying to build the eval board of si8244 which is basically a half bridge design. I want to drive subwoofers with it. Is there any issue with bus pumping which is usually observed in Half bridge design?
Did anyone listened to the si8244 eval board? how is bus pumping with it? these days some diy members say that bus pumping was old generation issue but with new gen its not a problem.

A friend has loaned me his 521 complete system for a couple of months. System includes 2 Emotiva amps ,analog crossovers and speakers and all connectors/cables. Only issue is I have is no sound )-: . Crossovers have both red and green LED's lit -is this normal? Have tried two different pre-amps -so some sort of weird pre-amp failure is ruled out ? Secret handshake ? Hidden mute function ? Moon phase ?

I attach schematic for traditional hybrid amp that runs +-17vdc and has a series electro cap and resistor as a simple way to protect phones from electronic failure ... according to D. Self. I don't understand how this polarized cap survives polarity swings.

I tinkered with parallel opamps, as seen in the O2 amp, which worked great even with 62 ohm AKGs. Now I want to try hybrid discrete circuits but I am wary of mistakes.

2. Can feedback be taken from the load side of this circuit.

Hallo. Im jack from indonesia

I disassembled the vintage two-way bookshelf speakers: Denon SC-C3. I was a bit surprised with their crossover networks. They have only high-pass filter on the tweeter comprising a 3.3uF and a 0.47mH combo forming a second-order filter. And they have no low-pass filter for the woofer. The sticker on the cabinet is labeled crossover point at 4kHz which is consistent with high-pass’s component values.

Although I was surprised, I could remember that there’s a case in which the designer may intend to utilize the “natural roll-off“ of the woofer. However, by doing this, there are few disadvantages which are the dispersion, woofer’s break-up/beaming and off-axis radiation problems. So, does it mean these issues could actually be ignored?

If so, what would be the tricks for using this method? I mean how to choose the proper crossover frequency for the high-pass filter of the tweeter with the presence of woofer’s off-axis response variety i.e. 15, 30, 45, 60 degrees? Because, in typical configuration, the woofer would be employed low-pass filter below the frequency where off-axis variation curves occur.

This project is considered an upgrade to DAC1136, as the chip for DAC1136 is difficult to obtain. However, DAC1146 is relatively easy to purchase. I purchased 2 and they are very new. There are two versions of DAC1146. The first version has a plastic shell that is all black with silk screened white font. The internal R-2R part of this structure uses an AD7541 ceramic encapsulated gold cover plate. The second version is a plastic shell with white stickers, which uses ceramic packaging for the AD7541. Regardless of the structure, it can refresh you and his voice is very good. It is not something that IC can imitate. I like modules.Now share with everyone.You will get his PCB at a very low price. But he is in China.If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email: 410746700@qq.com，My store address: hikvocal.taobao.com

Many people in China like PCM63P and consider it an irreplaceable project compared to PCM1702. Because PCM63P has a more delicate sound, and PCM1702's digital defects cannot compete with PCM63. So I created all the projects related to PCM63.Now share with everyone.You will get his PCB at a very low price. But he is in China.If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email: 410746700@qq.com，My store address: hikvocal.taobao.com

Six chips can work in the same environment, which is the best way to choose the one that suits your listening experience. I also created two methods. Operational amplifier and TUBE output. Just select the digits through format conversion.Now share with everyone.You will get his PCB at a very low price. But he is in China.If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email: 410746700@qq.com，My store address: hikvocal.taobao.com

Hi
I am Xaver an a Elektronics Enegneer.
I have already built my first preamplifier. With an integrated phono stage. The amplifier has a 5751 input tube in the phono amp and after that a e82cc. The line-amp after that is a parallel 6072a like the Kondo amps.

I also built a magnetic tone arm according to the Schröder principle on a Garrard 401 player.

My new project will be a horn loudspeaker with a JBL 2451 with aluminum cone in the midrange. The horn should be conical like Bill Woods.
Underneath, the bass horn is to be driven by a JBL 2227. The horn should also be conical.

Like to be with u

Hi 😀. I'm interested in modifying my existing receiver and I'm here for any and all advice.

If you would like to understand the title, please Google "the infinite monkey theorem"

This will be the start of my build log. A little background on this: For the past year I have been pouring through everything from white papers to text books, and sending out emails all over the place to learn about audio and speaker design. I've gone down so many rabbit holes. There is so much to learn and so many details you can expand upon in design. There's also something called the law of diminishing returns. At this point, I just wanna make something. So here we go:

T he objective is a set of active monitors with the best distortion figures possible while still being somewhat compact (and before you say it i am WELL aware of how many other designs there are out there). Some components will be expensive, others will not. Trying to be at least somewhat cost effective... I'm not the monopoly guy.

Here's the concept:



(I apologize for the chicken scratch, but I'm currently on vacation and decided to sketch it out a little with a notepad on hand)
Starting with the body: I found a little while ago a company that makes prefabricated carbon fiber parts. In this instance, a carbon fiber tube ( https://dragonplate.com/1075-id-x-48-carbon-fiber-tube ). Split that in half, and possibly a little more, and you have yourself a very rigid skin. It will be attached to a base (most likely MDF) and have a small bracket in the center (more on that later). Next would come a CLD layer, then the rest of the contents of the speaker.

The inside will be in 4 pieces. Each will contain a driver except for the one with the electronics. The 2 pieces on the sides will each contain a seas 8" sub. The placement will allow for force cancelation of each woofer allowing it to hit lower frequencies as well as cancel out any modes not supposed to be there. Additionally, because sound becomes omnidirectional at lower frequencies, and because it's a round enclosure, I shouldn't have to worry too much about distorting modes caused by edges and baffle stepping.

At the front will be an MTM configuration for the rest of the frequencies. This will be a small enclosure that has its own sound dampening seperately from the main chamber. Originally I was thinking about bliesma M74 mids, bit it seems purifi still wins this round with lower distortion figures. Will be going with a set of 4" woofers. The trade off there is efficiency. The tweeter will be a RAAL 70-20.

The last piece will be the electronics enclosure. Going with a hypex fusion amp for this one. I would have loved to design the electronics as well, but I do not have access to a lab at the moment to test them so this is the next best thing lol. From there it's just a little more sound dampening, a cap on top, and voila.

With all that said, I still need to sift through all the particulars. Am definitely going to need to dust off my CAD skills to make sure everything fits together the way I think it will. May fiddle with the design a little more, but all in all, I think it'll turn out great! Would love to hear from those a little longer in the tooth who have more experience in this than I. This whole thing has been a learning experience, and we aren't done yet.

Hi everyone,

The last few months have brought me some strange experiences in my sourcing of 45 tubes for my DIY amp. I had one seller who refused to provide precise measurements of his tubes, even though he listed them as testing "good". Which to me means nothing. Another one listed measurements and also gave me more details by email, but he backed out once I had purchased the tubes, perhaps because I mentioned that I was going to test them on my Pentavac tube tester.

However, the case that intrigues me the most is an experienced seller with whom I have been doing business for over 5 years. He has been selling tubes for nearly 30 years. He claims that the 45 is an extremely difficult tube to test and that he tests each one on four different calibrated tube tester.

When I ask him for more explanation on these testing difficulties, he vaguely mentions a temperature to obtain at the level of heating the filaments, as well as a "hard" material of it, without really giving more details.

Is the 45 really so difficult to test? I would like to have opinions on the question.

For my part, my Pentavac is equipped with an external power supply in 2.5 or 5V to test among others 45, 2A3, 300B. I have tested several 45 with it and I am always happy with its use. I have several that have tested with excellent emission between 95% and 105% of new for example, but also several that I had to reject. In two recent cases, I have returned them to the seller because they did not match the NOS measurements announced.

Finally, recent experiences have shown me a strong intolerance of some sellers who do not accept that we buy tubes from them if we test them afterwards. De facto, they reject the calibration of our tube tester and do not want to know anything about trading with customers who would be likely to test their tubes later with their own tube tester.

Personally, in this kind of business, it seems to me that we must at best have a common reference. The seller must be able to ensure the quality of the tubes he sells and the serious buyer, to be able to check everything after purchase.

Sébastien

F4 boards
Four were used for balanced headphone amp
Two for standard F4
$125 shipped to CONUS

Sorry for the clickbait title as this is not really about ESS hump. Or is it?

As I was testing my ES9822PRO board I noticed that the 1kHz FFT spectrum has high harmonics up to 100kHz and beyond.

Here is ES9038Q2M to ES9822PRO.



The harmonics of 1kHz continue throughout the spectrum albeit at a low level.

So are these harmonics coming from the DAC or the ADC?

Here is the same ES9038Q2M DAC but with AK5394 as ADC (fs is now 96kHz).



So it seems DAC is the culprit. Or is it?

To verify I switched to a 1kHz oscillator (my take on Victor's). Here is 1kHz oscillator + AK5394.



As expected spectrum is quite clean.

Let's repeat that measurement with ES9822PRO.



Surprise, surprise. The 1kHz harmonics are back. Also ES9822PRO has high harmonics.

So it appears that ESS architecture (Hyperstream?) causes high harmonics both in DACs and ADCs. Is this the cause for the infamous ESS sound?