I was having a read around cascodes and came across this 1956 thesis paper on cascodes - the interesting point is figure 1b, where it shows a parallel cascode:

https://scholarworks.montana.edu/xmlui/bitstream/handle/1/5007/31762100133923.pdf?sequence=1

Essentially the parallel cascode passes the signal from the anode to the cathode but decouples the path, unlike a anode-cathode serial connection, so that both run in a lower B+ (as a benefit).

I know of the cascode shunt but I thought that this was interesting as I've never seen another 'parallel cascode' so it may be called something else.

If it's useful and doesn't have any draw backs it may help reduce B+ voltages required for cascodes.

Hi! Looking for schematics or service manual for a ML No.532. Overheating problem in one channel.

Hi,
I don't know if I should buy this cd player, might be short of lasers if break it.It is a 2000 model, and on the back it says " serviced".I like the sound, has an analogue and " vintage" sound., my only fear is if the lens fail, I can't repair it.What can you tell me?Should I buy it or no?

Hi guys
I just had a look on a old radio shop, with 50 years of old stuff, mostly crap. But! I found these Philips drivers.
What are the chance that they totalley dissolve when i give them 5 watts?
I’m also aware of that the alnico magnets loose their Power over time, but isnt easy to re-magnitize?

Its paper surround with a kind of black glue on inside surround.
I just fell i love with the cork pieces and i think they never played.
/Thomas

Both drivers brand new in boxes. Price is £250 including UK shipping. Pics to follow.

Hi All. I just wanted to know what the graph I show here means. Can't understand it. Thanks. The X axis is showing mV?

Hi
I’m into a quite broad range of interests related to audio. Look at myself as kindof a «jack-of-all-trades» but not a specialist in any.
Programmer at heart, but ended active work on that a loong time ago now, and is working more on strategy, business architecture and project managment.

On the free time I’m a hobbyist woodworker. I also do some some painting, simple metal work and so on.
I have build several subwoofers and speakers, as well as assembled some amplifiers.

DIY speaker for our livingroom.



DIY speaker for my daughter


DIY main speakers and one of three subwoofers in the home theater/basement.

Greetings! Thanks for having me here.. plenty to learn and hopefully I can share some of the unique things that I have learned!

I am building a pair of horn 3-way speakers for a buddy. I have zero experience with horns but decades of diy experience with cone and dome speakers. I assumed the usual diligence with control of edge diffraction and surface reflection by building the mid-range horn loaded JBL 2452H and super tweeter JBL 077 into a suitable frame with chamfered and rounded edges. The crossover between mid and super tweeter is active dsp at 6.4 kHz, Bessel 24 dB/Octave. The drivers are accurately time/phase aligned.
Here is the issue. A single speaker measures and sounds fine. However testing the stereo pair at the listening position with pink noise, lateral head movement produces clearly audible rapid phase cancellations and re-inforcements. I determined the main culprit is the mid-range horn loaded JBL 2452H by muting the super tweeters. Each mid-range performs adequately on its own without the phase swings but not together. In effect, comb-filtering to a degree I never experienced with any conventional cone/dome combination.
I am tending to the conclusion that horn loudspeakers, whilst able to perform adequately as a single mono speaker system, will not image accurately as a stereo pair.

please please
thanks.

I recently got some 3-4 RPM motors to turn some small mirror balls.



They spin a little too fast for my liking.

I have a variable frequency AC supply I built using an old Bogen 60 watt amp, a 15Vac to 120Vac transformer and one of those cheapie function generator kits I bought from Amazon which I made to run a record player that's slightly too slow. I tried the motors on it and found 40Hz makes them spin just about right.


So I'm thinking of building another variable frequency AC supply only this time I want to try one of those class D amplifier boards I can get from Amazon or Parts Express and a similar function generator kit along with a power transformer run in reverse to develop the voltage needed as the class D board will be a good bit smaller than the Bogen and a lot more efficient.

How well would a class D amplifier board do feeding a signal into a transformer driving a minimum 52 watt load?

As I do with everything involving audio power amps I will use my oscope to view the waveform while I do extensive testing under load to be sure the amp does produce a clean sinewave.

Before I go and order a power transformer I'll try some I already have.

The motors do run a bit warm on 120Vac, but do run on 100Vac so I'll run them on the lower voltage.

I'll also figure out some sort of voltmeter to use so that I know what the output voltage is.

Morning. I wish there was a dedicated noob forum because I hate clogging things up with my stupidity...but I need help.

So, I have a preamp I really like, a lab12 pre1. It's pretty old (14 years I think). Well I've done a few kits and speakers and they went well despite me knowing absolutely nothing and I thought, hey, let's see if a fancy volume control and capacitors make a difference to a preamp.

So I changed out the various power supply caps, removed the RCA inputs as I only needed two and I thought hey less wiring can't be bad. Installed a khozmo volume control and a switch for the inputs.

Everything seemed good and I felt, and still feel, I had everything connected the same as it had been.

Well, I get no sound at all. Zero noise whatsoever.

I've since gone through checking solder, removing the switch in case that had anything to do with it, replacing the old volume pot, staring at the "before* pics etc...

I checked continuity from input to output and:

I do not have continuity from (+) in on the board to (+) out.

I do have continuity from (-) in on the board to ... everything including (+) out...and basically every other point I check anywhere on the board. I don't know if that's good...?

What Im really hoping for is some basic troubleshooting help. What can I try or test with my simple dmm? I'm at a loss at this point.

And yes I've learned my lesson about getting ahead of myself without understanding what I'm doing. I would really like to just get the thing working again and then reassess my learning strategy.

I have pics of my before and after but there's no available schematic.

Hey everyone,

Looking for some guidance because both of our old EV MTL-1 subs died this week—thanks to someone getting a little too confident and disabling the limiter on our DSP 🤔... so now we’re in a bit of a rush to find a solution.

For now, the plan is to grab two modern 18” woofers, throw them into one of the MTL-1 cabs as a temporary fix, and then start building proper new subs as soon as possible. Not too worried if the sound isn’t perfect in the meantime, since those drivers will eventually go into the new build anyway.

We usually play bass music (sometimes punk) to crowds of 50 to 200 people, both indoors and outdoors. We’re not after an earth-shaking, rave-style bass setup—just something clean and kind of flat, but with a bit more low-end extension than the MTL-1. I’m also considering building two single 18” subs instead of another dual-driver design, since modern designs seem way more efficient and might even outperform two MTL-1s with half the drivers. Thinking of something along the lines of an L-Acoustics SB18. But we can still be interested in dual-driver design...

Our tops are bi-amped EV RX 115-75s, and I’ve got some great people around me who know their way around CNC builds. The only thing is, their experience is mostly in dub sound systems, which is awesome, but not exactly what we need for a multi-genre PA. They can build solid subs, but I want to make sure we go with the right design that works well for bass music, but also other live style of music (punk, rock, etc).

I’ve searched the forum quite a bit, but I haven’t found a good breakdown comparing modern sub designs for this kind of setup. If anyone can recommend solid designs or point me toward helpful discussions, I’d really appreciate it!

Thanks in advance!

I came across an example today of a member using chatGPT to generate a post. They were open about having done this, first time, but then added a second post, also AI generated, but which didn't make this clear. It saved them time, apparently.

This bothers me. I'm not sure I want to be reading posts written by an AI, especially if the authorship is not clear.

I looked to see if there's a forum rule about this, but I can't find anything.

Hi. I have an original McIntosh MC2205 service manual to give away, just pay the shipping and Paypal fee.
let me know if interested.
sB

Def Tech Super cube 1 amp. Load crack then dead, any ideas. No burning visible anywhere. Caps not bloated,

Guess I need to start here?

We’ll Im a DJ who plays heavy bass JunGle. Started collecting gear for a sounDsystem worthy of bringin some Bass along with mid/highs with enough clarity. (to hear the Mc).

Hi Guys,

I'm desperately trying to get my first valve pre to work with my TDA dac based cd player and again I have ran into issues with what seems like 120hz noise.

I had help with getting the bias resistor correct (lAMPIZATOR DESIGN) and I tested the pre and was kinda happy but when you turn it up there is a very loud buzzing when the volume is increased.

This is my orignal thread about bias resistors:


I have the exact same kit as the person in this thread and he also talks about buzz, its all I have to go on. This pre uses high voltage and I rather not guess anything. Any help is greatly appreciated:


Please note the pin 9 is floating. My ac is 220v and directly across the smoothing cap is 288V DC. I have used the 240v mains input and used the 2 6.3V to heat the tube (not using the centre tap) (they are actually 3.15v each) My filament voltage is 6v.

The sound is great at low volume but when I turn my amplifier up there is a loud buzz. I used an app and around 120hz is spiking, its fast and loud.

I also tried bypassing the 2 smoothing caps with 0.1uf 400v and it didnt make any difference. Thanks

KEF T52 Tweeter from KEF Cantata loudspeaker.

Might anyone out there have a line on KEF T52's for sale, or information regarding how the KEF T52 tweeter can be disassembled?

I've taken the large screw out of the back of the unit, but it's still firmly bonded together.

Figured that I'd get some insight if any exists out there for something this old (1977) before I start applying brute force to the unit...

Tnx.

Andrew Drouin

Hello,
I want to play again with DC motors as well on turntable, like the Maxon A-max 26 110189. Long time ago I did joined a group buy for a motor and a current mirror type of speed control, it worked, but also tried to implement Manfred Huber's speed controller. That time I gave up, but now I want to restart.
Do you know if that or similar circuit is available for DIY?
I know some people run the DC motor with only a straight stable voltage, but I would not like to keep adjusting it manually. I'm looking for projects which either put some feedback on the platter or filters on the motor current for commutation and measure that.
What DC motor control would you recommend for best result?
Thanks!
JG

As I was investigating tweaks to an onboard bass preamp with a 3-band tone control here, I found LTSpice (of which otherwise I'm a big fan) rather frustrating: there's a lot of interaction between all bands and components, every time you have to enter a component value, rerun the simulation and see what it does, even if you step it you more or less have to guess which values will make sense, and often you have to adjust two or more components at the same time to get what you want.

So, I decided to make an Excel spreadsheet where you can adjust all components quickly with spinners and see immediately the effect on the frequency response. It started small but, well, you know how it goes: one thing led to another... Anyway, I thought some of you might find it useful, so here it is (see attached):



Some random comments:

• All calculations (based mainly on Wye-Delta and Delta-Wye transforms) are done in Visual Basic and I've included plenty of comments, but unless you can read code, it may be difficult to figure out how it's all calculated. If someone is interested, I'll be happy to explain.
• At the top left you have a drop-down list with three options: 2-Band, 3-Band "Classic" and 3-Band D. Self. The schematic shows the two 3-band topologies, the 2-band is the same as the "Classic" without the mids control. What I mean by "D. Self" is the one that @DouglasSelf shows in "Small Signal Audio Design" 2nd. edition, Fig. 15.31. I don't know if it's his design but I haven't seen it anywhere else, so I assume it is. The "Classic" is one of several other topologies you will find, I chose it because it's the one used in the bass preamp I mentioned and it's the closest to the Self one, as shown in the schematic it's trivial to change between them.
• As I was playing with it, often I found myself arriving at something reasonable, then screwing it up trying to improve it and not remembering what was the last good set of component values, so I added a couple of places where you can store what you have so you don't lose it as you keep tweaking. Then you can swap either of them with the current design. For illustration purposes, I include one each of the three topologies modelled.
• The "Min. Input Z" shown corresponds to the bass control at 0 and treble at max for the 2-band and bass at max, mids at 0 and treble at max for both 3-band options. I've found that this is the worst case. It's also the worst case feedback impedance with the controls at min instead of max, but in a real circuit you will also have whatever load impedance the opamp sees, so once you're happy with your design, you would take it to LTSpice, include the rest of the circuit and see what the real load impedances are.
• I think the rest is pretty much self-explanatory, but that may well be because I made it... Play with it, see if it makes sense and I'll be happy to explain anything that isn't clear.

I think that's enough for now, hope you guys find it useful, comments and questions always welcome.

Cheers,

Cabirio

Edit 9-Dec-24: Version 1.1 attached. Just a small correction (no effect on calculations and plots): the "2B", "3B C" and "3B S" style labels just below the "Swap" buttons didn't correspond to the actual style, now corrected.

Edit 13-Dec-24: Version 2.0 attached. A couple of features added, see post #5 below for details.

Hi all,
I have collected number of articles related to Vinyls, Turntables, Tonearms and Cartridges over the years. The subject is fun, interesting and foundation of modern high fidelity. So posting list of such articles which I hope you may find useful. worldradiohistory website is major source for such articles so in appreciation a big thank you for the website creator. I have take printout of specific pages as I dont like reading online for long duration.

LIST :
(Subject) (Author) (Magazines from which one can access them).

1) Hum, Rumble and Noise - By R. E. Cooke - Wireless World October 1959
2) Vibrations in Gramophone Turntables - By R. L. West - Wireless World September 1959
3) Turntable Rumble and Pickup Arm Design - J. Walton - Wireless World September 1962
4) Limiting Factors in Gramophone Plastic Deformation and wear of groove walls - D. A. Barlow - Part 1 - Wireless World May 1957
5) Limiting Factors in Gramophone Pickup Design Continuity of stylus Groove Contact - Part 2 - Wireless World June 1957
6) Inner Groove Distortion - R. S. Oakley Jr. - Audio June 1962
7) Pickup for low record wear - J. Walton - Wireless World April 1959
8) Pickup Design - J. Walton - Wireless World July 1960
9) Turntables - Joseph F. Grado - Audio
10) Gramophone Record Deformation - J. Walton - Wireless World July 1961
11) Groove Deformation in Gramophone records - D. A. Barlow - Wireless World April 1964
12) Pickup Arm Problems - John K. Murray - Wireless World April 1964
13) How records are made - Gary Stock - Audio June 1980
14) Mats & Clamps by the number - Edward M. Long - Audio April 1988
15) Phonograph Reproduction 1978 - Anderson, Happ, Jakobs, Karlov, Kogen, Mastricola - Audio May 1978
16) Phonograph Reproduction 1978 - Anderson, Happ, Jakobs, Karlov, Kogen, Mastricola - Audio June 1978
17) Stereophonic Record Pickup - F. Oakes - Wireless World January 1959
18) An Approach to pickup arm design - J.S. Wright - Wireless World April 1967
19) Better Pickup Arm Performance - Len feldman - Radio Electronics - January 1980
20) Understanding Turntable Specifications - Len feldman - Radio Electronics - February 1980
21) i) Practical Parallel tracking pickup arm Part 1 - Rod cooper - Wireless World December 1979
22) Parallel tracking Pickup arm modification and improvements - Rod Cooper - Wireless World July 1981
23) The Bizarm - Ernie Lowinger - Wireless World December 1977
24) i) Pickup arm Design Techniques 1 - Tejinder Singh Randhawa - Wireless World March 1978
25) Mercury Switch for Parallel tracking pickuparm - Rod Cooper - Wireless World April 1980
26) Simple Pickup arm Design - David Read - Wireless World November 1980
27) Understanding Phono Cartridges - S. Pramanik - Audio March 1979
28) i) A New Turntable Arm Design Part 1 - Edgar Villchur - Audio September 1962
29) i) The Skating Force Phenomenon - James H. Kogen - Audio October 1966
30) The Diamond as a Phonograph Stylus material - E.J. and M.V. Marchu - Audio Engineering July 1950
31) i) Torsional Stability and the Unipivot - J. Bickerstaffe - Wireless World January 1966
32) Measuring Gramophone Pickup Performance - J. Walton - Wireless World December 1967
33) Tracking Capability of Phonograph Pickups - J.G. Woodward - Audio March 1967
34) i) Trackability 1973 - J. Kogen B. Jakobs, F. Karlov - Audio November 1966
35) Design of transcription Turntables - E. W. Mortimer - in house magazine of the Plessey Group - Google Search for pdf.
36) i) The Lateral Mechanical impedance of Phonograph Pickups - J. G. Woodward, J. B. Halter - Audio engineering June 1953
37) Skating Force Mountain or molehill - R. S. Oakley Jr. - Audio March 1967
38) Dynamic Thrust in pickups - J. F. Crabbe - Wireless World May 1960
39) Understanding Tonerams - S. K. Pramanik - Audio June 1980
40) Equivalent Mass Fact or fiction - Roger Anderson - Audio March 1978
41) A New Concept in Diamond Styli - Dr. Hedi Benz - Audio August 1972
42) A Practical High Frequency Trackability test for Phono Pickups - C. R. Anderson, P. W. Jenrick - Audio August 1972
43) How we test a Phono Cartridge - Magazine Article - Audio August 1972
44) Phono Cartridge Q. and A. Mainly for beginners - Magazine Article - August 1972
45) i) Pickup Arm Design 1 - J. K. Stevenson - Wireless World May 1966
46) Determining the tracking Capabilities of a Pickup - H. E. Roys - Audio engineering May 1950
47) Pickup Arm Design Requirements for low tracking weight and immunity from vibrations - J. Walton - Wireless World June 1959
48) Versatile Stereophonic Pickup Necessity for a low tip mass - J. Walton - Wireless World August 1961
49) Stylus Mass and distortion - J. Walton - Wireless World April 1963
50) SOUND Chapter 1 - Edgar M. Villchur - Audio September 1956
51) Pickup Tracking errors - Edgar M. Villchur - March 1952
52) High Fidelity phonograph Cartridge - Technical Seminar by SHURE Co. - Search title in google

Notes :

• Have posted this in various forums
• Most articles can be found in worldradiohistory website
• For others search in google buy title in quotation marks.

Regards

Hello lads.

I'm repairing these amplifiers, as long as it involves repairing the power supply I have no problem, but if it involves repairing the audio section we don't know what the output mosfets with code R6 or R7 or R8 actually are.

do any of you have any ideas?

SALE PENDING

Two PassDIY Pearl 2 phono PCBs, populated and working perfectly! All genuine parts of the best quality. Ask any questions you like!

Asking $100 plus postage from Toronto, Canada. Can also include a nice PSU PCB (unpopulated) if you ask nicely 🙂

Even at just $40 obo it's too far for me so please put me out of my misery:

https://sfbay.craigslist.org/pen/ele/d/half-moon-bay-parasound-dp-2000-ultra/7820751754.html

I needed some additional storage for what I consider my "recent cache" - things I'm listening to or things I picked up. One could argue I'm getting lazy with filing. I saw some cool ones at Turntable Lab, but didn't want to spend that much and I wanted something that was easy to assemble. Click here to read more. Reach out if you want the plans.

SWR documentary how a high-end turntable is built: Login to view embedded media

From my early days listening to Yellow Brick Road on my brother's headphones to making my own sub and satellite for college to rescuing B&o gear to my beloved McCormack DNA 125 -- I have owned and probably kept too much gear. For the last few years, I've been interested in rescue. I've re-coned some speakers and tracked down belts and other things to keep some equipment around. I get a little thrill when I find something unexpected at thrift stores and have saved dual cassettes and turntables to help friends build analog systems

In another thread, regarding amplifier distortion measurements (started by xrk971 some years ago), I recently posted some questions about distortion measures of my 2A3 SET amplifier. I really appreciate all the answers I got in that thread. But for not polluting that excellent thread with my specific questions, I´m now starting this thread.
Initially my question was however my measures was reliable, but rapidly the discussion were focused on how to improve the measured amplifier and to remove the deviations shown in the FFT-plot.
Now, I would like to rewind the discussion to were I started it, by -step by step, show how i proceed with the measurements and If I did something wrong. By that, conclude if the plots I get is reliable. Later i´m open for a discussions on how to progress, and how the particular DUT (amplifier) can be improved.

Hardware:
I´m using an old HP laptop (with Windows 8.1) run on batteries, put it in flight-mode, not having the risk of interruption from my internet connection. No virus- or other software is installed on this computer. I know that he measuring harnesses aught to be shielded, But I din´t have access to such cable, so I used twisted pairs, tried to keep them as short as possible.

Soundcard is Focusrite Scarlet Solo 3´rd gen which has the following interfaces:

• Input 1 (XLR). Ballanced Mic input with an internal pre amplifier.
• Input 2 (TRS). Ballanced Line level input.
• Output 1 (TRS). Ballanced Line level output

Environment:
All measures are done in my basement on the Swedish countryside, where I have some current consuming gears (electrical heater and led-lights) in my surrounding. Although I have not seen any deviations in my measurements that I could derive to radiated EMI or mains power spikes, so I think the environment is okay for these measurements.

Software:
I have downloaded the latest appropriate REW software.

Focusrite Solo Calibration/loopback:
When soundcard calibration was made, I looped Output 1 (TRS connector using TR tabs) to Input 1 (XLR connector pin 2 & 3). I also connected Output 1 (TRS connector using TR tabs) to Input 2 (TRS connector using TR tabs).

Note: Input 1 (XLR) is a mic input at Solo, and not a line input as in some other sound-cards offer. Hence I use a 10:1 attenuation (voltage divider) when measure speaker output signals (see below for detail). Input 2 is a line input.


In REW Soundcard Preferences, the setup were done as below. Levels were adjusted according to the bars and a calibration file was generated. With the calibration file used the frequency response is ruler flat from some Hz to +30kHz.


The same loop back setup were used for testing equipment noise using REW internal generator and FFT-analysator:
Note that Y-axle is in dBc (level related to the carrier (1KHz) set to 0dBc. Distorsion is low and noise is in the -115dBc region.


Measuring DUT:
When measuring the device I removed the loop back harness, and instead used this one.
The power resistors are two resistors of total 8 Ohm. Banana plugs are connected to speaker outlet respective to a Fluke true rms ac volt meter.
Parallel to the power resistors there is attenuation network of 100K resistor in series, and between them two 10K resistors, making a virtual center tap and a 10:1 attenuation for each leg.
This "pseudo balanced" signal (two hot and one virtual ground) was connected to the XLR at Soundcard Input 1
Soundcard Output 1 (TRS connector using TR tabs) connected to av RCA male attached to the DUT input. and also to Input 2 (TRS connector using TR tabs)



Turning the DUT on with no stimuli added. this is what the FFT-plot shows. As seen there is an annoying peak at 50Hz and it´s harmonics. Note that there are also peaks in the 8kHz - 13kHz region. I have no idea what causes that?



Measurement 1W output (2.82Vrms /8 Ohm)
With 1kHz stimuli added the plot shows as below. 50Hz peak increased to -60dBc and one can see that the 1kHz stimuli (and its harmonics) are modulated.



Anyone seeing anything odd or faulty done in this so far?

Hi All,
Joining this forum to improve on my execution of my first DIY DAC project - Lampucera. Hopefully if this goes well my next project will be a pair of KT88 Tube Monoblocks.
Thanks

Let’s make a dedicated thread for this project to keep things consistent. Links to relevant threads are appreciated! 🙏

Project Goals​

I’ve been eager to start a new project. My current Audio Note setup sounds wonderful but has reached its peak development for now. I don’t expect this build to replace that system, but for variety’s sake, it would be fun to build something myself. While I’m not experienced in advanced speaker design theory, I understand basic principles and have a good grasp of furniture and component design as well as common manufacturing methods and materials.
This project will proceed at its own pace (likely slowly). The goal is to build a relatively risk-free, "safe bet" speaker with minimal iterations and prototyping.

Ballpark Concept​

• Size: Bookshelf/monitor, max height ~500 mm
• Enclosure: Sealed
• Configuration: 2-way preferred for simplicity, but I’ll consider 3-way if benefits (like lower f3) are predictable and budget-friendly
• Drivers: Bass driver 8" or 10" but curious…
• Amplification: Hypex Fusion or equivalent
• Budget: Max €2000 per pair (excluding labor and cabinet materials)

Design Rationale​

• Sealed Enclosure: Works better in my space than vented solutions. I value the responsiveness of sealed designs over absolute bass extension.
• Target Frequency Response: Ideally around 40 Hz in-room. If that’s not achievable, the design should allow easy future integration of a bass module or active subwoofer for possible future, higher SPL situations like psychedelic garage parties with beer bongs and people in weird clothing.
• Performance Focus: Prioritize good value for money and performance within budget constraints.
• Listening Environment: Apartment with neighbours, 3-meter listening distance, typical listening level < 75 dB.

(Very Loose) Inspirations & Preferences​

• Consider a [sealed configuration] Antelope Atlas i8 as very rough reference
• Dynaudio Focus 10 as another…
• An ideal, financially completely unrestrained (and boring) option would be a Dutch & Dutch 8c, delivered and custom setup at my home while drinking my expensive wine in my tweed jacket and claiming to know many things others don't
• Paper-cone woofers preferred for their pleasant sound, though not mandatory
• Controlled directivity is a plus but not essential

Current Component Ideas​

• Woofer:
  SB Acoustics SB23NRXS45-8
  (8-inch)
• Tweeter:
  Wavecor TW030WA11
  (low fs of 425 Hz and a waveguide)
• Amplification:
  Hypex Fusion FA122
• Cabinet: ~25 liters
• Crossover: Target ~1.6 kHz

This setup would undercut my budget by ~€500 and seems promising, but I’m open to better suggestions.

Questions for the Community​

1. Is the proposed 25-liter cabinet size appropriate for the SB Acoustics woofer?
2. Thoughts on driver matching, particularly the Wavecor tweeter and crossover frequency?
3. Any other driver/enclosure recommendations within the budget?
4. Would you rather fight one horse-sized duck or 100 duck-sized horses?

Thanks in advance for your suggestions and insights!

How do I calculate the output (line) impedance of this circuit?

Hi everyone! I want to make the ESP project 13 low noise amplifier with the addition of a balanced pre input.

I need some insight in the power supply design. This is what I've come up with so far. Any thoughts?

1.
Transformer (Toroidal, 22.7V & 34.6V AC taps)
2.
Two full-wave bridge rectifiers (each using four BY550 diodes)
3.
Filtering capacitors:
30V section → 4700µF, 50V
48V section → 2200µF, 63V
4.
Voltage Regulator (LM317 for 30V output)
5.
Phantom Power Switch (SPST) before the 6.8kΩ resistors
6.
Phantom Power Resistors (6.8kΩ, 1%) → XLR Pin 2 & 3

Having a pair of old Threshold amps I wonder if it is a real benefit to install solid caps (that's how ZenMod calls film caps 😉) over the big electrolytic PSU caps like this of course:


I ask this because I read an article called ´‘Power Supplies: Commentary for Consumers’, by Nelson Pass.
Excerpt about capacitors from that article:
"Big electrolytic capacitors have a small amount of inductance, or "coilness", in their makeup, a result of the spiral winding of the capacitive
film. To reduce the effect of this inductance, film capacitors which have
low inductance are often placed in parallel, so that at high frequencies
the current flows a little more easily.

An examination of the numbers will provide some insight here. It is common for the inductance of a large electrolytic capacitor to cause its
impedance to begin increasing at about 10 KHz so that its impedance is a large fraction of an ohm at 100 KHz.
Placing a film cap in parallel will keep the impedance to .1 ohm or so above this frequency.

Is this important because audio has real power at these frequencies?
No. Audio has power which declines at about 12 dB/octave above 5 Khz, and real musical slew rate figures are a fraction of a volt per
microsecond, meaning that practically no power is needed at 100 Khz.

However, high frequency impedance can be important to the stability of the amplifier, particularly with more complex circuits, as the source
impedance of the power supply starts figuring into the feedback at frequencies of a mega-Hertz or so. Interestingly, some designers have
depended on a particular source impedance of the supply at these frequencies for stability, thus it is possible to destabilize the amplifier
circuit by paralleling film capacitors across the electrolytics.
In general, however, film caps in the power supplies are a good sign from the consumer's standpoint."

Maybe I draw the wrong conclusion here but it seems that NP doesn´t recommend/finds it beneficiary to install solid caps in the PSU over the electrolytics.
I'm curious what is your opinion in this matter.

I have sony xplode 4 ohm 2 x 4 ch 800, 4 ch 1000, and 2 ch 1300w set of amps all rated at peak. 4 amps but i dont need to use all. I have a 1973 opel gt that I'm replacing the drivetrain and redoing the interior as well before repainting the body.

First i want your opinion on what to use for the low bass in the back of the car. 4th, 6th, 8th order are all saying they are better than ported or sealed. What is better for something using lower watts?

Looking at how newer generation boxes look, I'm guessing i should build the inside like 2 ported boxes, smaller cubic inches behind sub 60hz, front bigger cubic inches 30hz, if 8th order 45hz for last port? Am I way off? Would they cancel each other out at the end?

Is it better to use a 6th order with 60hz in smaller side and 35hz for bigger side? Would the bigger side have louder base and smaller be quieter like how a normal ported works?

I'm going to use a fiberglass box inside another fiberglass box on outside because the inner box needs to be stronger than the outside that's just used for resonance. I might use 1/4 mdf on the inside of the inner fiberglass box to make it easier to bolt together.

2nd question
I guess I should start with what size sub? single or dual? I can run a pair of dvc subs bridged 800w amps giving me 1600w. A single sub 1300w bridged would allow me a bigger box for a higher order design.

Note:
there is no usable space in back as a truck because there is no tailgate, so I can use the entire area for a box. 36x36x30 and I have space behind the seat to where the rear box is from floor to roof as well.

2nd note:
I want one 4 ch amp for 2 pairs of 6.5 component speakers that will be for midrange and 4 tweeters will use the 10.1 touch screen built in amp. The stereo has a great speaker, surround, and subwoofer equalizer for each output

3rd question:
1st option:
I was thinking of making ported fiberglass boxes for the doors to have 6.5 midbass subs for a 4 ch amp bridged or run each channel if they are dvc.

Second option:
Put all speakers in front and use a pair of 8 inch behind the seats on the sides sealed infront of rear sub(s).

Conclusion:
I want good bass and think separating the rear being most powerful 1300 watt, second smaller subs using 500x2 watt, speakers 200x4, 4 tweeters 45x4 will blend for good sound.

Since all are in their own boxes, they shouldn't create distortion with each other but that's a guess based on setups I've seen for the last 25 years.

I know lots of tweaking will be needed.

Hi Everyone,

I've been interested in how a high powered, single-ended amp might sound for some time. I suppose a large Aleph could solve that mystery. The BAF2015 SE 50w has a couple of nice twists, one being it uses Schade feedback to give the MOSFET triode like curves. It's also a really simple circuit.

I suppose it's worth while thread to start, unless one was started already.
I searched and went back a few pages, but didn't see anything, so here it is.

Attached is a screenshot of the schematic with its creator. In the shadows...😉

I'll crate a wiki once things get rolling so that FAQ can be answered.

Hope to hear from interested people.

Vince

Notes:

Dave Hill at Jensen, the JT-112-L (what's on the schematic in the video) is an obsolete part number, the part still exists as the JT-123-FL, and the various mounting permutations of that transformer.

Power transformer: 500va minimum, 600 to 800va recommended.

10k resistor adjustment. See post #49.

To adjust CCS, change .2 Ohm resistors. For example, to lower current by half, increase resistors to .4 Ohm.

Changing The Circuit Voltage:

The question- If I were to lower the voltage of the circuit from 60v to 40v, would the drain of the mosfet be at half the circuit voltage, e.i., 18v-20v?
Is this similar to the ACA bias adjustment? Would I then monitor the drain voltage while adjusting the bias at the gate, arriving at around ~20v?

Answer from ZM- Yup, goal is to have symmetrical behavior of amp's output , in voltage domain .... thus resulting in highest possible power (from voltage window) ..... finally resulting in so-so symmetrical clipping


NP: "If your source is cap coupled, then you will need some resistance to ground.
Try a value like 10K and watch for motorboat (with load). Decrease the
resistance until the motor stops."
Example preamps: BA3- Pre and B1 are cap coupled.
Set input to ground on SE amp input before Jensen input transformer.

NP:
1) The amplifier must be driven by something with a resistive component
to its output impedance. That means that the source cannot be capacitively
coupled, or if it is, there is a resistor to ground after it. Otherwise the
amplifier will motor-boat.

2) The DC Drain voltage of the circuit's gain transistor is temperature
dependent, but it generally should be fairly stable if the heat sinking is
adequate - If it's not stable enough you can put a 5 or 10 watt 220 ohm
resistor from Drain to Source to stabilize it better. I don't think you need
the complexity of a servo.

SoundHappy: [Adjustment of input resistor] Can be done with 10 K potentiometer.
You try find the lower R without motorboat sound , next step measure resistance on potentiometer
then replace potentiometer with fixed resistor who have resistance value close to measurement Enjoy

For more on stabilizing see posts 455 and 456 of this thread.


@ Diyers
Voltage at lead outs of two 1000 uF caps are less 10 V.
10 KuF output cap have 59V for short time at power on.
After few minutes at 3A2 full bias , tension go down to ~ 15 V.
Anyway 50 V rated big can is safe.

PE seems to have a full line of planar drivers just released.

GRS PT2522-4 3-1/2" Planar Tweeter 4 Ohm

GRS PT2522C-8 3-1/2" Planar Tweeter with Back Cup 8 Ohm

GRS PT6816-8 8" Planar Slim Tweeter 8 Ohm

GRS PT6825-8 8" Planar Mid/Tweeter 8 Ohm

Let's hope they have better consistency than the standard Chinese BG knock-offs.

Greg

Hello, I'm Radu, interested in class A amplifiers design. Looking forward to contribute to this forum.

PA150 LM3886 pcb with all components,with Jantzen input capacitor for sale:87€, that you could check here:
https://www.ebay.de/itm/325598035746
I will offer a DRV134 IC and it's pcb for who buy a stereo set, that you coul check here:
https://www.ebay.de/itm/326039146998
IC's are new and are not applied on the pcb,like main capacitors,power connectors and SMD output resistors
the other components are already assembled, with genuine components.
Machined Heatsink with the machined copper hardware and ceramic pads can be supplied the cost is 62€,
It is available for purchase in another listing.
I have also power supply pcb's that are on my other listings.
More than one set available
Tracked shipment to European union

The Idea was to create something relatively portable to take out with me when camping and hiking. To do that it needs to be powered by battery and power outlet as well, slightly more than a boombox (soundwise, lookwise) at the same time make use of combination of technics (3d printing, woodworking…) to make easy on myself.
Inspired by Paul Carmody’s Isetta.

Here is the final result:


More on
https://forum.arylic.com/t/visetta-boombox-ac-and-battery-powered-3d-printed-up2stream-amp-2-1/9165

Hi folks,
I have a Stereo amplifier Board from Wondow - offering a whopping 2x 900W @6ohms and 10% THD.
AB32551 WONDOM T-AMP HV 2 x 900Watt Class D Audio Amplifier Board

The datasheet promises a SNR or 99dB (A-wheighted).
The datasheet notes a 450µV A-wheighted noise rms voltage - which would correlate to 45Vrms output voltage. The spec is with 120Vdc so the amp deliver arrount 84Vrms).

But when connected to a power supply (I tried various SMPS and laboratory supply) the output noise on a connected tweeter horn is substantial.
Even at 48V it is much higher than on comparable Wondom products (AB35511 WONDOM T-AMP 3 X 500Watt Class D Audio Amplifier Board).
I tried shorting the input jacks - without much of an improvement.

A request to wondom did not deliver any feedback.
Any idea how to improve or what to test?

1. How can I test the RMS noise with DIY equippment?
2. How can I simulate the A-weighted characteristic?
3. Is there any means of grounding required?

Help is much appreciated!

Hi guys,

I am looking for a low SNR high power Amp Design that offers a full digital path.
So I want you use a DSP (like SigmaDSP) to deliver I2S signals to a PWM Modulator Chip (e.g. TAS555x from Texas Instruments).

These PWM modulators normally have integrated Noise Shapers and offer PWM signals to drive a power stage.
But they normally dont offer any means of feedback from the final AMP output to eliminate distortions or voltage fluctuations of power supply fluctuations.

Normally you add a Power stage like TAS5634 (2x300W) - the include the output stage, full protection and a feedback from output to PWM signals.


The Idea:

• Use a PWM Modulator Chip to produce PWM Signals for output stage
• Feed PWM Signals into discret MOSFET Power stage with fast and low jitter gatedrivers
• Add protection against crosscunduction, overtemperature and overcurrent

Questions:

• How can a feedback be implemented to modify PWM signals?
• Can a outputsignal feedback be avoided by sampling supply voltage and feedback measurement to DSP stage (BW < 1kHz)?

Any other cool ideas or design recommendations?

I remember reading a post by @abraxalito where he recommended a passive analog filter, especially for multibit dacs. I'm playing with an NOS multibit dac and thought I would try no filter and passive filters of a few slopes to see what the subjective sound differences are.

As I started simulating the filter, I realized how critical the input impedance and output impedance of the filter can be in the output response of the filter.

My first question is if I am correctly representing the impedance in my model? I'm using Micro-Cap 12 for simulation. In the schematic, I am using a pure AC voltage source with a resistor in series representing the output impedance of the dac. I am also using a resistor as the load representing the input impedance of the pre-amp following the filter. The load resistance is much less sensitive because it is a high impedance compared to the filter.

The listed output impedance of the dac is 625 Ohms which should be OK feeding a pre-amp but seems to have a large affect of a passive filter. Happily this can be tuned out of the system but I'm curious if others have found this in practice?

Hi,

I am wondering if anyone built a working track detection for a linear tracking turntable like Technics SL-6, J1, RCA MTT230 etc. The theory is clear. IR reflective sensors like TCRT5000 or ITR8307. But in practice it is really hard to build it reliable. Are there any better sensors available or what is the trick?
With some records the gaps are very small, coloured vinyl is hard to detect, the thickness of the record is an issue...
Would be very interesting if someone did some research on it.

I am a 18 year old from sweden i am a intermediate audio guy and i am pleased to be here.

Hello, my friend suggested the forum. I am interested in hobby electronics. I live in Turkey. I like analog audio, hi-end audio, and simple arduino projects.

I am a PC tech' who needed some ferrofluid for a KEF 104/2 rebuild in my office, and could not find any in Canada (!). So I bought a good sized bottle of APG L11M from Ferrotec USA and have been breaking it down into syringes, each syringe holding enough ferrofluid to refill two tweeter units.

Cost is $25 CAD including shipping, mailed surface post anywhere in North America.

Hit me up if you need some ferro' folks!

Andrew Drouin
www.SpeakerFerrofluid.com

Hi,
I'm testing my inverted LM3886 and found significant distortion when testing a 4 ohms load. Here's my setup and schematic.
DC = +- 35.8V (a little high)
Green = components added for stability
P1, P2 = Probe location, using ground at input
Load = 4/8 ohms 100W dummy load



Here's the distortion at 4 ohms load


Here's peak power at 8 ohms


My question is;
1. At 4 ohms, I got much less power with significant distortion. Is this SpiKE protection? or what is it?
2. At 8 ohms, I got about 31W, which seems low given the supply voltage?
3. Possibility of fake chip? I got the chip 2 years ago when it was scarce as "old stock".

(Known issues of this board
-Occasional ringing oscillation, still can't fully catch it but it happens less after more stability components added
-If C3 is removed, it will oscillate and R9 in Zobel network will burn (happened twice!))

Any suggestion would be appreciated.
AP

Sadly it looks like Monacor have withdrawn the SPH-135C. They no longer list it on their site and many sources now no longer list it or show it as unavailable.

It is (was!) a carbon fibre coned 5.25” with very good excursion that I used in very small cabinets as bass drivers with lots of EQ. They produce an astonishing amount of bass for their small size.

I was thinking of using them in my next build as a midrange driver.

The most similar driver in terms of size, shape and spec seems to be the SPH-135KEP and is more expensive and visually very different with a bright yellow Kevlar cone and black phase plug rather than the carbon fibre.

TLHP still list it as unavailable https://en.toutlehautparleur.com/speaker-monacor-sph-135c-8-ohm-5-24-x-5-24-inch.html

I’ll have to very careful not to blow them up!

I’m sorry to see them go NLA. They have given me great listening pleasure and hopefully will continue to do so for many years.

The smaller SPH-100C has also gone although I never used that one.

Jeff.

Ecco la traduzione in inglese:

---

Good morning everyone,
I have built a DAC with two DA-7 MkII boards and an unbalanced output using a DS2206 transformer, and I am extremely satisfied with it. The sound is truly excellent, but I fear that the Vrms output might be a bit low, as you can see from the picture.

I am currently listening to it with a Naim Nait XS-3, and I have noticed that at low volumes, the sound feels "compressed," while increasing the volume makes it truly outstanding.

Right now, I am using Volumio on a Raspberry Pi, connected via USB to the JLSound board.

The next step I would like to take is building a preamplifier—possibly balanced—to connect to a Modulus-86 power amplifier (which I have yet to build).

In the past, I built a Nelson Pass B1, but since it has a unity gain, I fear it might not be helpful for my purpose.

Do you have any advice on how to proceed with the preamplifier, or any alternative solutions I may not have considered?

Many thanks to anyone who can help!

I have a pair of Genelec 8030A. The Left speaker had a 6 db lower bass and a bit of distortion than the other one. I changed the boards to find out the problem is from the board or woofer. After the change the healthy one not work at all. So I bring it to an electronic expert and He found the LM4780s not work. He connect the input pin of LM4780 to an active speaker and the sound was clear. We track sound to input pins but there isn't any sound on outputs so there isn't any problem in the boarad before amp. the LM4780 discontinued but I order from a Chinese website but the LM4780s were fake and didn't work at all. The electronic guy suggested to replace LM4780s with two TPA3118 and place them somewhere in the cabinet. The guy had a TPA3118 circuit and run it at 24v to drive the woofer. But the sound was very bad also at full volume was very weak and a lot of distortion. the cabinet don't have a lot of space and I don't wanna change the cabinet or cut it or...
Is there anyone can suggest a solution or had the same problem? What about TPA1316? How can I rescue the old 8030s?

Good day all. I'm having a wierd one with my Numark mixer. Let me try and explain the best I can. So the unit has a 5 bdan graphic EQ, thing is I get very little effect out from the uq on the speakers through a power amp, but get fulle effect from the headphones when plugged into the mixer. So im assuming it's jys after the headphone stage and before the output stage going to the power amp. I managed to get the circuit for it from Numark, and will upload it here now as a reply. Sounds really awful, and seems to effect most the up frequencies. As mentioned, through the headphones it's full frequencies. Thanx in advance

https://www.headphonesty.com/2025/02/scientists-reveal-pricey-hifi-setup-live-music/

Your speakers are amazing… just not that amazing.

No matter how much you invest in high-end speakers, amps, or cutting-edge audio tech, your hi-fi system will never truly replicate a live concert.

Click to expand...

I thought this was interesting but had the thought "don't live performances use speakers?".

Hi

I'd love to have JC-1 monoblocks, but these are big (like two of my A21), and I do not like their 35W constant power consumption..

A21 is fabulous, I compared it against two much pricier amps and still preferred A21 🙂

What I would like to improve:
imaging, more transparency and lower noise floor..
and Class A bias.. now is it 10W? 15W would be likely better..

I like the sound signature, so I merely looking for 'more of the same'..
I am not so strong in electronics, so the advises here I will bring to my engineer..

thanks in advance,
--Michael

Xsim is limited to 20khz, and REW 24khz. If my impedance graph is on a downward slope at those limits, I would assume that it continues downward. Is it a problem if the impedance drops to a very low value at ultra high frequencies? Would it eventually become a short circuit?

I found this random impedance graph online to use as an example:

[Moderation edit: Original thread title CamillaDSP 2 for piCorePlayer 9: Changed 17Jan25 ]

This is the support thread for a project I've published at
https://github.com/charleski/Camilladsp-for-pCP9

This includes a CamillaDSP GUI that functions with scripple's automatic samplerate-changer and the whole thing is done the 'tinycore way', with all the components running in RAM, rather than leaving part of it on a static partition. The installation has been designed to be as simple as possible, needing little more than copying and pasting commands into a SSH terminal, apart from a little bit of editing to specify the correct output card. If there's interest I might try to simplify that part further at a later date.

I've tested it on a fresh install of pCP9, but can only test with a USB DAC. If anyone runs into problems please let me know here, and I'd particularly like to know if it works with 'hat' DACs.

Anyone have experience with SPICE models of BSS84 especially those usable with LTspice?

The NXP model in the LTspice library seems closest to DS (datasheet) for Vds - Id but is still far out circa Vgs 2.5V

There's a Diode International model but that is WAY out for all Vds - Id

Da TINA people like a Zetex .subckt but I haven't been able to get it to work in LTspice. Anyone know what I'm doing wrong?

I'm new to LTspice .. especially when creating 'new' components.

After long hesitate and couple of PMs, I decided to open this thread.

Inspired by diyaudio member Dadod's thread, I've built power amplifier with Hawksford error correction scheme (HEC).
It's a split design, IPS and OPS. They are not enclosed by global feedback loop (which is not totally true, IPS has a jumper to set it, but only for testing purpose). There are two versions of OPS (diamond buffer quadruple), bipolar (3 pairs of NJW0281/0302) and hexfet (3 pairs of IRFP240/9240). It can deliver 200/170 Watt into 4 ohms, pcb is common for both types. Measured thd1 was 0.003% 50W@4.5ohm (or better, sound card limitation), slew-rate 120V/us.

K200 - OPS bjt, stable, built (schematic v1.5, pcb v2.2)
https://picasaweb.google.com/106882583920049206569/K20002?authuser=0&feat=directlink

K200M - OPS hexfet, under development (schematic v1.1, pcb v2.2)
https://picasaweb.google.com/106882583920049206569/K200M?authuser=0&feat=directlink

K4 - IPS vfa (blameless), stable, built (schematic v2.3, pcb v2.0)
https://picasaweb.google.com/106882583920049206569/K4Frontend?authuser=0&feat=directlink

K5 - IPS cfa, stable, built (schematic v1.2, pcb v1.0)
https://picasaweb.google.com/106882583920049206569/K5Frontend?authuser=0&feat=directlink

ProtectOne - auxiliary circuits, built (schematic v1.0, pcb v1.0)
* on/off toggle switch
* transformer soft-start
* mains LC filter
* loadspeaker protection (DC, delay)
* OPS RL network
https://www.youtube.com/watch?v=QMYUAJ7LMV4



I am rather builder than circuit or pcb designer.
My knowledge about amps are at quite low level.
This is my first complex design, so, if you can, help me to improve it, please.

Hi everyone,

I’d like to introduce you to one of our popular products, the TSA8498B (Apt-X): a powerful 4 x 100W Class D Bluetooth Audio Amplifier Board. This is a 4x100W audio amplifier board with a new AudioB plus Bluetooth module that supports Apt-X. It's integrated 2xST high performance TDA7498 which supports dual channel audio amplification. Each channel is capable of outputting nominal power simultaneously and continuously. This board can be powered by any DC14V-39V* power supply. The power input port can be a power jack or screw terminal. The DC input jack is 2.5mm with positive core polarity, And if you use a screw terminal, please pay attention to the polarity!

It has a smart cooling system, and the fan does not work in normal cases to reduce the noise. The fan only starts when the chip temperature is > 65°C. Once the temperature goes down, the fan stops running.

It's perfect for your Hi-Fi application, the audio source can be RCA input or Bluetooth. Compatible with all Bluetooth devices that support media audio, including iPhone, and Android. Let your smartphone paired with this board, play music. So easy!



We tested it. It also works well with 12VDC power. But we suggest using DC14V-39V power if possible.

Features:

• Size: 15.5cm x 11cm
• Apt-X supported
• Smart cooling system
• Bluetooth 5.0
• External mute control port
• External Bluetooth/LINE IN control port
• Working voltage: DC14V-39V
• Over/under voltage protection
• Over current protection
• Over temperature protection

Hi, I wanted to build a discrete version of the LM4562 op amp following zubr's drawing of its internal schematic (link). However, I'm having trouble getting it stable. Maybe someone who has more experience on amplifier compensation than me can help me.

There is always a resonance at 20 to 40 MHz, which - even if the loopgain looks fine - leads to full or partial instability in the square wave test. I think it is visible in the datasheet's phase plot as well, but there it is tamed down (see attached images).

Some observations:

• The datasheet loopgain has knees at around 10 Hz and 1 MHz suggesting a compensation capacitor in the 100 pF range.
• Replacing the emitter follower buffered current mirror with a different type notably changes the phase response.
• I'm not sure about the role of Q6 (zubr's schematic). Normally it's off, suggesting it's role is protection related. Removing it has some influence on loopgain still. There is the option to remove its emitter resistor, but therefore either increase the VAS emitter resistor or reduce the current mirror degeneration resistors. zubr noted he wasn't sure if it has an emitter resistor or not.

Project files are attached. The plots show loopgain, FPBW, PSRR+, PSRR-. I'm using the Cordell SPICE models.

Any help is appreciated.

I’ve been trying to build a cartridge for a couple of years now. Getting pretty close to finishing it, but came to the conclusion that I don’t have a proper arm for it…
Have been using it on an old Lenco P77 I machined a new headshell for.
Having bought all the machinery (Small lathe and mill) for the cartridge, figured I might as well try my luck at a tonearm as well.
Had someone else’s 12” project arm I could use the bearings from, but it needed a new yoke, bearing house, armtube and counterweight.
Made a model in CAD, took some basic dimensions off of an Ortofon RMG and grabbed a couple of pieces of brass.
Everything fits together nicely. No loose parts, nice sliding fit on the counterweight and headshell connector. Used some thick walled aluminium tube of which I turned the inside diameter down to get to a nice fit for the connector. Also put a strip of balsa in the tube to dampen it a bit. Still need to shorten the tube, but wanted to see if everything would move as it should.



Still need to figure out the correct angle and length for the tube… The geometry is still a bit complicated for my simple brain. 🙂

Edit: design is largely influenced by the Old Ortofon arms.

* Asking price reduced: $575 OBO.



I've made too many things and am selling the Mar-Ken10pwTT I made last year. These unique speakers are finished with coffee (Trader Joe's French Roast) and satin polyurethane. Made of 18mm Baltic Birch ply, solid Brazilian cherry, and natural wool for the interior lining.

Dimensions are 21"T x 11"W x 10"D; weight 26 lbs. ea.

Remarkable bass extension, clarity, and dynamics.

I hate to let these go but thought someone on the forum might be interested. Local pickup preferred but will ship at buyer's expense (from Tulsa, OK). Due to their size and weight, they might need to ship in two packages.

Hi everyone,

My name is Fiona, and I’m really interested in electronic modules, which is why I’ve joined DIY Audio. I’m excited to be here and look forward to sharing experiences with all of you. In the future, I hope to discuss more about electronic modules and learn from everyone.
Looking forward to connecting with you all!

Best,
Fiona

This one goes into protection as soon as 12v is applied (no remote). I replaced :
C20
C23
C27
C30
Still does the same.I'm only getting 2.9vdc on pins 8, 11 and 12 on the power supply IC (S494P).

n/a

Caveat emptor! The threaded mounting bushing was completely loose on these input transformers, so there wasn't any way to tighten the nut down. When pulling a little tension on the threaded grommet to get it to stay put, the bottom of the transformer can popped right off.

HI,
I need a simple 150v regulated PSU (with transistors) for EL36 screen grids, my last project is a EL36 SE amplifier.
Thanks
Alain

Hello everyone, new here,

I'm passionate about vintage electronics, from amplifier to tuner and turntables i love restoring them while diving into their circuits to understand how they work. Excited to learn, share, and discuss with fellow enthusiasts!

Hi all, Just wondering if anyone has come across this issue. i bought a used yorkville nx750p powered loudspeaker (15” B &C Neodymium woofer) and during a gig the woofer starts to bottom out and you can hear the voice coil clack as it hits the magnet. This happens well into the party and before that it is able to produce good bass with no audible distortion so it seems to be a thermal problem. Im not over driving the speaker. When it starts bottoming I enable the 90hz high pass filter on the speaker and it plays normal and can get by. Since I only have this single speaker I borrow my cousins which is a 750p series 2. His cabinet is much newer and and some small differences but the biggest is it has a ceramic woofer instead, I’m not sure if it came like that or someone swapped out the woofer. His speaker can keep on going strong with no issue. He bought his used and told me the store changed to ceramic as the neo woofers we’re failing.

I replaced the volume pot in my Technics SA-206 with a ALPS 4-Gang Motorized pot. The motor is controlled by a L298n board connected to an ESP32. My question is: is it possible to somehow convey the current position of the pot to the ESP, (e.g. voltage) without incurring introducing a bunch of digital noise into the signal?

Hello!
Rumour has it that the circuit can use CCS for cathode follower.

How?

What about this one?
http://www.pmillett.com/current_source.htm

Thanks!

Do any of you guys have the PC -0766-C schematics, I'm trying to figure out the power fets numbers the 2 pc boards I have they used IRFZ40 but they don't match this board.

I have been recently thinking of building my own amp that can properly drive my Kappas 9.2i and any other future Infinity's I'm going to own.
I have not much experience with building electronics, besides recapping some old amps and reading a few books a long time ago. But I love playing around with this kind of stuff. So I would like get some input on where to begin.

I want a BIG and powerful amp capable of delivering at least 300 watts at 8 ohm and being stable at 1 ohm. MOSFET or SIT. Also playing first 20-50 watts in class A.

I know this will be expensive and maybe difficult to build, so I'm looking at this as a long term project.

So, where should I begin?
Can I use some of the Firstwatt or Pass schematics?
Have anyone here build a similar amp?

Hi, I'm working on a Sony receiver where the right channel is barely audible compared to the left. I put a test tone through the CD input and I took my oscilloscope and looked at the input signals on pins 6 and 8 and they match. The output on pin 2 and 3 looks the same as pin 6 where pins 11 and 12 are amplified quite a bit. Is this a clear indication that this IC is bad or could something else be at fault? I pulled out and tested some of the caps like c651, c655 and c565 and they're all within spec. I didn't see anything strange or out of line reading the voltages of all of the pins either.

I have genuine, unopened, B&C 18 IPAL recone kits for sale.
US $300 per kit.
Shipping is from Canada, to be discussed.

Hello fellow audio enthusiasts! I'm thrilled to join this community where passion for diy high-end audio unites us all. I have a particular interest in DIY audio projects and am a big fan of Sansui and Decware amplifiers. I'm eager to deepen my understanding, share my experiences, and learn from the wealth of knowledge within this forum. Looking forward to engaging in discussions and exploring the fascinating world of HiFi together.

One pair used but verry good condition. Verry nice slunding drivers. In 40L netto enclosure - 3dB down to 34Hz.
Shipping i side EU. Price 150 euro/pair plus 19,50 euro shipping inside EU. Payment Paypal.

A friend dug these out of storage and gave them to me. They were never used and look to be perfectly fine in the packaging. I see they were often part of a well known “Minimus 7” bookshelf speaker.

I guess I’m wondering what a nice short path to using them might be? My wife could use some book shelf speakers in her office. But I don’t know where to start in terms of a tweeter or crossover.

Edit: a thread about M7 upgrades directs to these little crossovers. Or there’s this thread about upgrade crossovers.

I've acquired an Audiolab 8000A which is popping its mains fuses.

I've checked the power supply with the rails to the output stage disconnected and all is OK - voltages OK, minor ripple.

Looking in to the power rails the resistance on both channels and rails is the same and showing no shorts or low resistance so I think the output transistors are OK.

With the power connected to the power amp again and the amp powered via a DBT nothing looks untoward - the expected inrush then a steady dim glow.

However, when directly connected to the mains the transformer briefly hums as though under high load and the fuse goes.

The only anomaly I've found is that one of R495/R496 which are 4R7 2W resistors is down to 2R8 when measured out of circuit. That resistor is in series with a 100nF capacitor, which are across the output.

Is that circuit to filter high frequencies to prevent oscillation? Could oscillation be what's causing the high current draw and be due to that filter not working correctly due to the resistor's lower value? Given the amp blows its fuse so quickly it's not that feasible to detect with a scope.

It also looks like some of the output transistors have been changed - perhaps for unsuitable replacements?

Hi Folks,

My name is Rich… a few folks know me as the guy who provides support and service for folks with Merlin Music Systems speakers and Joule-Electra tube gear. I’m a EE and have been playing around with electronics since high school and have been into (high end) audio since my early teens (I caught the disease from my dad being raised around AR3A’s, Dynaco gear, Thorens turntables etc). As a EE, my speciality was more in systems/project engineering which is what I did in the defense industry during the 80’s and early 90’s before deciding to go do my own thing in the world of high end audio.

Though (full disclosure) I am a (very small) high-end audio retailer, close to half of my work is taking care of old Joule-Electra gear and Merlin Music Systems speakers and a some other stuff (mostly tube stuff). I knew the owners/designers at both companies well and loved their gear. With these guys not around (Bobby P at Merlin passed in 2015 and Jud Barber at Joule retired and closed his company down in 2013 and has passed on 2 yers ago) I’ve done what I can get help keep that gear going and making music. At times hat has meant being creative and DIYing some fixes for things. 🙂

What do I DIY then??? I do some of my own mods/tweaks to things (don’t really have the time to build complete things from scratch these days) Latest project is trying to learn DIPTrace PCB design SW so I can make a simple replacement circuit board which will allow different/better volume and balance controls in later Joule-Electra preamps (including my own of course). It’s been slow going. Could really use some help with this and DIPTrace’s on discussion forum has not been of any help. Hoping I can find someone here who has some actual circuit board design experience (which I am a total newbie to) who can help (this idiot) out!

Last major project was resurrecting a 25 year old pair of Joule-Electra VZN-160 OTL amps which have sat in storage/unused for close to 20 years (a lot of filter capacitor replacing, some cap reforming, doing some mods to improve serviceability, and then testing testing testing to make sure the amps were reliable and problem free before sending them to a new home.

Thanks for reading my rambling long post…

Cheers
Rich