Hello
i want to replace ferrite coil with air coil in crossover.

I measured values of ferrite coil:

1.56 mH, 0.22 omh.


Is it acceptable to use an air coil that has the following values:
1.50 mH, 0.30 omh

if the difference is too large, what should be the tolerance?

I always been lazy with math i am a screwdriver person

So before i start digging in my rusty math i seek quick advise from Solid state people

In a class AB amplifier which has most of the times feedback lets suppose that one user uses cables that for some reason have some or excesive capacitance

--is the capacitance itself that introduces a filter in the circuit probably effecting high frequency response ? lets suppose that the cable has 10-20-50-or 100pf capacitance does this form a filter that is in the audible frecumncy and that will effect the total result ?

--is the relation of feedback involved and this will after all effect the total result ?

kind regards
Sakis

I ask for help. Tell me an example of using the drivers specified in the attachment.
Thanks.

As the title says really.
I've got a pair of Dayton RS180-8 7" and I have a pair of XT25 on the way.

What type of speakers would you build with those?

I don't mind floorstanding speakers as long as they aren't huge.

I've been trying to learn speaker design software during the day, but I would prefer not reinventing the wheel if there already are good designs with these drivers out there.

And I have spent the better part of 2 years or so getting decent at KiCad and PCB design. Unless necessary, I'd like to avoid learning another set of software's that I'll use for most likely this one project.

I have one pair of each so a dual 7" 2.5-way or similar is out.
Grateful for any and all help and advice.

Just purchased a used jl 500/5 . Was told working all well.
Brought it home did a power test no speakers hooked up to it .would turn on but the low ohm light would aluminate for approx 2 seconds then fade away green power light afterwa5ds, I tested each channel with a 4 ohm bookshelf speaker. All channels work well gain works,channels clear sounds equal loudness . When amp powers down low ohm light turns on right at the end ?

Also I removed the cover and powered up, all green leds come on at same time same speed .same brightness.

I called jl audio tech no real information gained .amp was too old for accurate knowledge. He was leaning towards internal short.

Looking for a pair of decent 1.5uf capacitor for my super tweeter crossover.
And if possible, not critical, a pair of thier l pad attenuators.
Both for my super tweeter for my fostex 208 horn speakers to my fostex super tweeters

When taking near field measurements what is the correct way to sum the output of multiple ports and the cone into one single response graph?

From Jeff Bagby's "White Paper - Accurate In-Room Frequency Response to 10Hz" he gives an example for adjusting for one port: The smaller of the two, usually the port, will need to be lowered in SPL (dB) because its smaller area will apply more pressure on the microphone making it appear louder. Its output needs to be lowered by the ratio of their areas using this formula: Lower the port by 20 Log (Port Diameter / Cone Diameter). So, for our 6.5” woofer, with its 5” cone area, working with a 2” port, the port output will need to be lowered by 20 Log (2 / 5) = -7.96 dB, or roughly 8 decibels"

For dual ports he give this example: for dual ports, find the total port area of both ports and determine the effective diameter for the combined area. Now, take the measurement at only one port, find the ratio of the total port diameter to the cone and make the calculation and then add 6dB. So, for our example, if there had been 2 – 2” ports then the port output would be lowered by -7.96 + 6 dB = -1.96 dB. For dual woofers and a single port we will need to do it the other way around and subtract another 6dB from the port output.

However, I'm not understanding this. If I calculate the total port area of the two ports you get a combined area of 6.28sq inches or an effective diameter of 2.28". If I then calculate the SPL adjustment by using the ratio of diameters (effective port/cone) = 20 Log (2.82/5) = -4.97dB. If I then add the 6dB I get +1.03dB.

In my particular situation I have a woofer with an effective diameter of 4.375", two ports of 0.625 diameter (front), and one port of 1.25" diameter (rear). I am trying to apply the correct adjustment to a port reading so I can stitch the woofer and port measurements into one SPL graph. I think I can figure it out once I understand how to do it correctly.

My current setup is as follows:

ThinkPad to 3x Startech 7.1 USB cards that feed 12 zones (mostly stereo, a few mono).

Running MS4L, which is an LMS/SS-Lite based setup. It lets you do the following:

1. Separate out USB sound cards into whatever mix of channels you want. You can take each 7.1 card and have 8 mono channels, 4 stereo channels, or a mix of both (e.g., 6 stereo and 2 mono).
2. You can have zones that overlap in inputs, so you could have a 1st floor zone and a living room zone.
3. LMS plugin support for Airplay, Spotify, etc.

But....

It is a pain to setup. When you have multiple USB interfaces, they are assigned to channels in order of boot and can end up mixed if you accidentally pull a cable. You have to walk through and figure out which channel is which manually which is tedious as hell. Etc.

So before I bang my head against the wall setting it up again, I want to see if there is something better.

Key requirements:

1. Let me split soundcards in the same way into multiple zones
2. Spotify support is absolutely required
3. Interrupts for doorbell and other alerts (mp3 or other)

Nice to haves:

1. On the fly synced grouping
2. An easier install
3. Room correction for each zone
4. Headless operation
5. Airplay and UPnP support

I looked, and most of them are RaspPi based (e.g., Moode, Volumio, Max2Play). I could do this, but 12+ Raspberry Pis isn't that cheap either and it feels a bit silly to have a bunch racked up instead of one more powerful system.

Need some clarification from the experts here...

I am trying to assemble a 5.1 active XO, pc based media player...

I already have the 10+ channel amplification for my 5x 2 way speakers, and I was looking to buy 3x ADAU1701 DSPs to feed the amps, but realized the whole media I consume is PC based (netflix, plex, spotify, etc.), and that I could use my PC (Equalizer APO and rePHASE) as crossover, but the problem is that I need a 10+ channel DAC or multiple soundcards... So, what choice do I have?

a). 10+ channel DAC = too expensive, and beats all the purpose.
b). Multiple USB sound cards = this would represent a problem to configure multiple outputs without delay and configuration problems.
c). Get a 16 channel USB interface like the Behringer UMC1820.

Would this last alternative work? When I plug the UMC1820 will it be recognized with EqualizerAPO? As an USB interface, all the sound output's thru this interface? The price is very atractive, buty I don't what to spend that money if it's not going to work for me. I assume hte sound must be outputed as PCM, so no bitstreaming, and I will be limited to 24bit 96khz (not a problem and I will probably use 48khz).

So the chaing would be:

PC > UMC1820 > amps > tweeters and woofers

I am not looking uber audiophile quality, I just use it for movie watching and some music, but not critical.

Thanks in advance for your help!

Hi,

I'm looking for someone to build a pair of loudspeakers--fairly simple (OB) construction but I have no time. I also don't have the skill to get the level of fit and finish we want in our LR.

I'm in Socal and am hoping for someone local.

Best
Max

Hi
Just stumbled acrooss andrea ciufolli's 300b schematic using lundahl interstage tansformerstwixt the driver tube and 300b
What do people think of this (looks mighty simple)?
What is the general concensus regarding this topology..
Thanks for your time
Nick

Hi all.
I am currently in the progress of restoring a pair of (good quality) DIY Futterman OTL's.

Being OTL's, speaker impedance obviously becomes critical, and I am considering building a pair of dedicated 16 ohm speakers for them as a side project. I will need adwise though, but first a couple of pre-requisite informations:
The speakers will be positioned in a living room with open access to two adjacent rooms with a combined footprint of around 750 sq.feet. One speaker will have to be placed in a corner but this haven't been a problem in the past, as there's plenty of room for the sound to escape into.
Sound level is fairly low, hardly ever above 90 dB.
Distance between listning position and speakers 10 to 12 feet, with the same between them.

So, what do you suggest, look for 16 ohm speakerchassis which predominantly exists in the PA industry and design a 3 way say 10"/6" with a 1" horn/bullet tweete?
Or build something with two units in series, like an isovent/isobaric solution in the bass, D'appolito for midrange and two tweeters, potentially with one facing rearwards?

Just throw in your suggestions.

Regards
Thomas

LT3045 LT3094 Positive and Negative Low Noise Regulated Linear Power Supply New | eBay


Any first hand experience or measurement with this PSU board? It uses the LT3045 and LT3094. If those were genuine IC, the noise performance should be very good. The small heatsink may need a 30-40mm cooling fan if more than 100 mA output is desired. The small board size is very attractive for low power, phono stage application.

So my situation:
- 1000W class D subwoofer amplifier (velodyne microvee)
- If I use my mobile phone as audio source- works perfectly
- If I plug it into subwoofer out on my receiver (denon x4500H): pretty serious hum.

So clearly this 'sounds like' ground loop hum, but:

- Second subwoofer has no such issues, so the receiver is probably fine
- Ground Loop Transformer has maybe a little effect but not much
- Shortening cable length down to 1m, swapping power polarity, same power strip as amp.. all no luck

My best guess is that the amp is broken, perhaps dried up caps (and in fact I used ESR Meter to check the ones that are easily reachable and one cap is definitely 'dubious'...)

But does this make sense? Why is the thing working perfectly with the mobile as audio source, but not with the separating transformer? What else could this be?

Up for sale is a pair of new unused ERSE Super Q 2.0 mH inductors. These are solid core devices wound with 16 AWG wire and have DCR of 0.143 ohms. Parts Express sells them for $22.48 each.
ERSE Super Q 2.0mH 16 AWG 500W Inductor Crossover Coil
The price is $32 for the pair + shipping and PayPal fees. I have 5 pairs available.

This cracked me up today browsing... Goes beyond poor translation

"The tone is different from the silicon tube, and it is different from the tube and the field effect tube. It has its unique charm and style, like lobster and chicken soup."

#Aliexpress NZ$ 94.11 | The sound is fascinating pure class A single-ended tube output preamplifier board, the sound is transparent and lingering LG267H
AliExpress

What strange comparisons or superlatives have you seen in descriptions for audio equipment which made you chuckle?

Hi,

It is written page up and page down about sonic traits of using different types of coupling capacitors. But in a regular ss power amp, does anyone have any experience in changing feedback resistors for no other reason than sonic improvement?

I got to thinking about this when I swapped the reasonably good Jantzen Superes 10W resistor for Duelund Cast resistor for the tweeter series resistor in my diy speakers. I have done cap swopping a lot, but I have not tried that many resistors.

I found the Jantzens a real upgrade over standard ceramic types, but I was really surpriced at the difference the duelund resistor gave. More so than capacitor I would say.

Hi. I need help with understanding actively crossed over systems. The thing that confuses me is if i for example use 40w woofer and 20w tweeter and have active crossover how do i match the levels? Correct me if I'm wrong but if i use lower power amplifier for tweeter than woofer than tweeter will have lower gain. So am I supposed to use same amplifier for woofer and tweeter and let the crossover handle power distribution or am i missing something?

Would anyone know where to buy a LRS350-48 PS? I cannot get one from Meanwell in the UK as they will only supply with a VAT number (Business ) which I do not have as just looking for personal use. There are companies called Agouk and Ledlightingsave which have identical web page so think it is the same company. Just want to avoid rip off's without paying silly money for it. Thanks.

Bob Shane, the last of the original Kingston Trio passed away Jan 26, 2020 at 85 years old.

Here is link to NYT obituary...
Bob Shane, Last of the Original Kingston Trio, Dies at 85 - The New York Times

So, just got this player quite cheap, in very good cosmetic condition and laser/transport seems fine, too. Owner claimed it was working fine with digital out, but no analog out. I don't have a standalone DAC to test, but I believe him ,as all the rest is 100% true. Checked analog out signal path and in fact no audio is coming to the opamp filter stage at all. Just some very, very low static signal (my scope has trouble triggering that waveform for so tiny its amplitude), when amplified on poweramp with preamp, it sounds like static, with very, very low and far away hear something of the music it is playing on the CD.

I googled around and got some schematics, but the important section, the DAC, is not of SE edition ,has a different DAC. This one uses CS4391. I checked all digital signals from transport with my scope and they seem fine (SDATA, SCLK and LRCLK), although with a bit of HF noise on the top of the wave form (but I guess it's normal, they all look quite good), and yes, they do arrive at the DAC. Also, IC seems to be well soldered and nothing measures odd, except for one thing: the resistance from RST pin to +V, was like 200 ohms. When operating, voltage was measuring only 2,78V, which is weird. It has a soft start delay and hardwiring it to +5V made the output static a bit more intense, but nothing solved.

Started to research and found a lot of reports on the internet of the CS4391 failing, especially the lots produced around 2000 (well this player is from 2002...), and people reporting static noises. To be sure, I substituted all three passive components which make the soft start reset circuit, nothing changed and they all measured good.

So, I suppose I can conclude almost 100% sure that the DAC IC is toast??


Also, what is more important: if the IC is fried, which is very likely, the problem of taking it out and soldering a new one arrives, as it is tiny, I'm good at soldering, long years experience and have a good soldering station, but very little experience with SMD work. I mean, I don't say that I couldn't get the stuff needed and try. But there's a certain risk that I might damage some pcb pads and that's a serious problem to fix, some have traces under the IC...

So, I guess I have two options here:
1) get a new CS4391 (or a couple of them, should something go wrong) and take the risk, or, as I was thinking in modding this player for myself,
2) go the total adventure route and build a DIY DAC for this CD player??? What do you think? Has someone done this with this kind of transport (it outputs SDATA, SCLK, LRCLK, but also a normal one wire digital signal + ground, which goes directly to the digital outs on back panel, so there would be two kind of interface available to connect to custom DAC).

There's one thing against building my own DAC board (whatever kind): I was really curious to listen to this player with the original DAC from Crystal, as it got some nice reviews and was curious to compare it against my loved and modded Marantz CD40 (like: modern against vintage 😀)...

One the other hand, a custom made DAC might be much better and make this player far superior? Now an important question: is the transport worth the hassle? I mean, they do have a nice copper box around the servo logic with big, blatant words (and ICs shown for that in schematic seem state of the art of that time) and I do like the front panel (which seems in great shape, no display issues, like they often report), BUT... the KSS-213 is quite basic and cheap, at least when we compare it with the great swing arm transports, for example, and this one seems quite noisy, it even makes some slight ticking noise when the CD runs, like if it was something uneven (don't think it's the CD...). Although seems to read and track fine.

Thanks in advance to all opinions and hints I get, I'm feeling a little bit lost here right now...

I would like to launch a series of discussions about the design of low-distortion sinewave oscillators.

There are already a number of threads dedicated to the subject, this one being a typical example.

Together, these threads represent a huge amount of information(s), but they tend to be large, messy, and mix up new ideas, old designs, SOTA designs, and revolve about all aspects of such oscillators and sometimes unrelated subjects.

With thousands of posts, any relevant information tends to be drowned in an ocean of "noise".

Here, I will discuss each aspect in turn: gain control will be the first one, but I also intend to discuss topologies, active elements (gain blocks), amplitude acquisition and filtering, passives, etc.

I am not interested in the current state of the art: this can be found on the net, or here, without too much effort.
I would like to see new approaches, and they could be new takes on existing solutions, or completely new solutions.

I am going to illustrate that point, based on the classic jFET VCR example:



First is the classical implementation, with all its known issues.
This basic circuit can be improved by using a more clever summing scheme, to improve the accuracy and speed of response: SOTA.
Both the previous circuits suffer from a residual non-linearity and limited dynamic range.
It would be interesting to find a corrector network, to lower the distortion and improve the dynamic.
Only the last circuit would qualify, because it brings something new.

I am going to prime the discussion by presenting a gain control based on lambda/Early effect.

The Early effect, and its FET counterpart, the channel modulation are non-linear effects.

They are generally seen as a problem, because they increase the THD of amplifiers, but would it be possible to take advantage of them to create novel types of VCA's?

The answer is (apparently) yes. This drawing illustrates the principle:



The output resistance of the transistor can be modulated by the collector current or the Vce.
The dependence on the Vce is what causes the non-linearity in amplifiers, but Ic provides a convenient, direct means of controlling the resistance.
Of course, using a single transistor would be somewhat impractical.
A push-pull configuration seems ideal, since it neatly solves DC issues etc:



Now that there are two active elements, the Vce term disappears, meaning the synthetic resistor becomes linear (assuming the Early law is cast in bronze, which is not exactly the case unfortunately).
Things are not that simple though, mainly because complementary transistors are a fiction that doesn't hold in reality (in silicon at least).
Parameters differ widely, and Vaf (Early voltage) is heavily affected: PNP's have a much lower Vaf than NPN's.

The solution is to go all PNP:



This is a first, half-practical example. I will examine later its shortcomings, and possible remedies.
I will also introduce a figure of merit, to evaluate more objectively the various alternatives.

The simulation shows an amplitude sweep, from 6Vpp to ~0.6Vpp

Datasheet still available on OnSemi's website -- discontinued by OnSemi about 5 years ago.

NJL4281/4302 15A/350V 230W hfe=80-250 cob=600p
NJL3281/1302 15A/260V 200W hfe=75-150 cob=600p

Rochester has the NJL4281 on offer @$2.59, no offer on the complementary device.

4 each NJL4281DG/4302DG (8 devices) $10, shipping conus $7.45, row $14

PM if interested.

Not at all confident about this...so need to check that this will do the job.

Have found this standard grade Toroid on the Toroidy.pl site.


TTS0300 - Transformer TS300VA/230 - voltage to 50 V - Shop Toroidy.pl


Needs to replace a burnt out ILP 73033 (300VA 50-0-50) in an 80's built

Hart Kit JLH Monoblock amp.


It isn't audiograde.....but understand that the original ILP wasn't audiograde either!

Hi,

Edit: R2R DAC emulation implemented
Sound Distorter R2R 0.2.37.53




Many times while considering to order a new DAC, that should better than a previous, I asked myself how low distortions I do need practically. The question was always important just because any next DAC requires next growing budget. I believe the equation is not surprising for anybody.


So I wrote a tool to simulate controllable distortions from -110db to - 40db and to add the distortion to a software player. Sound Distorter

Also in the background I've been thinking about no-linear distortion in general.
Actually there is a set of audio equipment genres, such as R2R DACs, tube amplifier, with distortions noticeably higher than expected.
However the sound of such devices is often perceived as desired, not just specific. Ordering an R2R DAC (for instance) just to check the sound is not the best idea to me (at least), the experiment doesn't look affordable. So I think about whether it's possible to simulate the same specific distortions programmatically and compare the difference.

I would like some feedback if the subject is curious to somebody else.

Thank you,
Serge

Working on another one of these amps .

Does anyone know the values of these components

R222,223
R214
R225

They are all missing out of both channels so the 200 and 300 parts are missing

Alright, I'll start by saying that I don't know whether this is the appropriate place or the Class D forums, but here goes...

I'm working on a proof-of-concept idea for a mobile karaoke setup. I have two cheap, Chinese class D amps that cost me $22 and $30 respectively, the first one based on the TPA3116 that I bought a couple years ago and a new one based on the TDA7498 that I literally just got in the mail today. They both share the same extruded aluminum "Breeze Audio" case, but I suppose that's not terribly relevant. I'm sure many of you are familiar with these. The new one is definitely more hefty.

Anyway, my proof-of-concept idea goes as follows:
I can back my Jeep Cherokee up into any random field, parking lot, etc. and pop the tailgate, and within five minutes have a working PA set up. The back of the Cherokee is the "table" where I set my laptop and mixer and the two amps, the two 12" speakers (Panasonic RAMSA WS-A200's if anyone cares) go up on some cheap stands, a mic stand is set up with two mics on it, and an 8" monitor speaker (RAMSA WS-A80) gets set up on some kind of stand (still working this part out) with a USB 3.0 screen connected to my laptop in front of the mics. Boom.

So here's my question:

The two amps are both set up stereo. Obviously I want to use the more powerful of the two (TDA7498) to drive the mains. The monitor only needs to be mono though, so should I consider attaching a dummy load to the unused channel of the TPA3116? I don't want to hurt it, but these little amps actually seem fairly resilient. Let me stress that no signal will be put through that channel.


Add-ons:

If anyone knows anything about wiring extra power into this system via a couple deep-cycle batteries so I don't have to run my engine/alternator all the time and still have enough juice to get me through a night without killing my car battery, any info on that would be awesome. Ideally I'd like the extra batteries to charge from the alternator while I'm driving. Even better would be if I could run the power from them back into my car in case I have trouble starting it in the winter, but I have no idea how plausible that is.

I'm already taking the car power from a cigarette lighter and running it into a 24v up-converter to drive the amps. I've yet to attempt driving both at once, so I suppose another question would be whether I should invest in another up-converter that puts out like 10 amps and drive both amps off that, or if I can use the two I already own that put out 3 and 5 amps. Will that make a difference? What's the more efficient way to handle this? The mixer will also need to derive its power from the vehicle but it takes 15v so I know I'll have to buy a 12-15v converter, too.

The mixer is a cheap Chinese model as well. It's an "ammoon" mixer with five mic channels and one stereo channel, along with some on-board delay/echo. I entertained the idea of using a small Behringer mixer I already own but those take AC power and I wasn't sure if there was a workable DC solution.

Any comments/info would be appreciated. I'll do my best to answer follow-up questions.

I am selecting some 18" subs for my scoopers and I am thinking perhaps Celestion FTR18-4080F's paired with Bryston 7B's. I know that's a lot of money in amps but they are the only ones I trust so much from my recording background and I'm not very well versed in selecting LF drivers. I'm still learning what is "high end" for LF driver brands other than TAD and Celestion and what amps are more pro or consumer grade.

Bryston 7B
Description: Solid-state monoblock amplifier. Output power: 600W continuous into 8 ohms (27.8dBW), 900W into 4 ohms (26.6dBW). Gain select and sensitivity: 29dB (2.3V in = 600W into 8 ohms), 1V setting; 23dB (4.6V in = 600W into 8 ohms), 2V setting. Frequency response: not specified.

4080F
Nominal diameter 457mm/18in
Power rating 600Wrms
Continuous power rating 1200W
EIA power rating 800W
Nominal impedance 8Ω
Sensitivity 97dB
Frequency range 30-3,000Hz
Voice coil diameter 100mm/4in
Chassis type Cast Aluminium

What do you think? Any suggestions?

Has anyone used the psvane KT 88s in there SSE. They have a nice blue colored tube. They ask if your amp is self biased with automatic shutoff or manual bias I think for this I should say manual?

Title says most of it really! I'm in town for a few days and I'd read that Sim Lim sqr/tower was where I might find some electronics components stores. Is this still the case?
Thanks in advance!

Hi
Can anyone confirm the model of the mid/bass drivers used in the above speaker?
I thought they were Audax HD20B25 H
but I have now seen that there are a variety of Audax HD20B25 then various suffices (J, E etc.)

Thanks

Hi,

I got a pair of Focal EC 165 Coaxial car speakers i don't use and i want to use them in a portable boombox build, but i want to make a 2.1 enclosure with a sub.
Which sub would work for this project? I will run it all from a TDA7498E 2.1 bluetooth 5.0 amplifier board 160Wx2+220W sub (AIYIMA TDA7498E Subwoofer Amplifier Audio Board 160Wx2+220W 2.1 Amplificador Power Amplifier Speaker Home Sound Theater DIY BTL on AliExpress) and a 29.4v battery i have made with the spot welder.

It needs to be
- 4ohm
- Need no more than about 15 liter because i dont want the boombox to be too
big. 6-8 inches would be enough.
- Need to be able to be used with 200w or less.
- go down to 35hz or lower.

Is this possible, any suggestions?

Hello all,
I need to get some recording software, but as I have no idea what to buy, I must ask for advice.

I need software that can run on both Windows and Mac. The more user friendly the better, as I am the most technologically illiterate teen I know. Basic is good, but I'd like something that won't hold me back in later years if I decide to invest a lot of time in mixing and mastering.

That's all, really. I already have access to a lot of good microphones and I'm sure I can find someone who can help me set it up. Any suggestions for good software is much appreciated.

Thanks!

And off topic advice. I'm wondering if anybody knows of the best or simplest way to extract data from a web site and then take that data and say send it to a serial port, I found this website TOP-15 best web scraping tools, web scraping software for data extraction 2019 | MyDataProvider.
Obviously there's a lot of applications for mining real time data from websites and using it to control various things.

An example is to look at the BOM website and look at the various weather stations looking for approaching wind gust and then controlling an external device by either
sending values to an external microcontroller to make the decision and control the hardware or the PC making the decision and sending the immediate command to the device.
The other thought was to reassemble the data and then send it to another third party web page.

It's not just the BOM, that's just one example. There are quite a few pages I'd like to mine real time data from.

Hello,
My project with these high end tweeters never started. (got kids 🙂 )
C25-6-012
So, I am selling one matching pair of Accuton (Thiel & PArtner) C25-6-12 in perfect condition.





Asking for 440€ for the pair + shipping.

HI all.
I am aware that the usual life span of electrolytics, subject to use is in the order of 15 years, give or take.

My question is, do film capacitors eg, polystyrene, polyproplyne etc suffer the same fate?

I ask this beceause a still have good stocks of Rifa / ROE / WIMA etc which have never been used, but are approaching 15 years old.

If any one can help me with this question it will be greatly appreciated.

It seems a shame to have to throw them out, but if they are no good beceause of age, Oh well!!

Regards,
George.

Hello Everyone,

I am having some difficulty with hum in a push pull amplifier I am working on. The amp powers up correctly, the B+ voltage reads about 10 volts above what I modeled during my design calculations, and everything seems OK with respect to component temperatures, capacitor polarities, etc. -- i.e. I didn't get electrocuted and the amp didn't catch fire.

But, there is a nasty hum present once I went to attach speakers (although I can hear a signal alongside the hum if I apply one).

If I ground the input grid to the first voltage amplifier stage (plate resistor loaded 12AX7) by turning the input volume potentiometer all the way to zero, there is no hum. The signal lead is taken off of the wiper, so turning up the pot increases the resistance between grid input and ground. As anticipated, the hum volume audibly increases as I turn up the volume pot. Can I interpret this as meaning that the hum is originating by some unwanted noise being imposed on the input stage's grids? Both channels exhibit similar hum.

I'm trying to rule out heater current inducing hum insubsequent stage's grid connections, tube imbalance, transformer shielding, etc., by virtue of the fact that grounding the first input stage's grid eliminates the hum.

Before I tear everything apart, some details about the circuit from input to 12AX7 grid:

-1k grid stopper

-100k volume pot, signal taken from the wiper

-0.2 uF film capacitors to attenuate DC

-26 AWG shielded cable from RCA jacks to input selector. Shields are connected at one end to the aluminum chassis. Cutting the shield connection didn't help anything.

-Both input selector and volume pot bodies are earthed by virtue of their contact to the aluminum chassis. Ditto the RCA jack's body. Initial signal inputs were with an iphone not connected to its charger. The hum is present without any input device connected to the RCA jacks.

-All signal grounds join at a single bus, which is then connected to a grounded bus in the power supply turret board. This is connected to IEC neutral. I am using an IEC plug with the earth connected to the chassis and no connection between chassis and neutral.

Any suggestions?

Hi I have found a shop in Denmark (where I live) that sells the Keithley DMM6500 for $950 + shipment. Thought that some may be interested🙂

PAIR OF HYPEX NC500 STANDARD OEM BUFFER BOARDS.6 MONTHS OLD. £40 incl delivery to UK.

Waymo (google) has started a driverless service in Arizona. There cars have put on over 20 million miles on real roads in real cities. Even if they prevent 80% of crashes they will save 30,000 lives a year just in the US!

Waymo – Waymo

And there saftey report.

https://storage.googleapis.com/sdc-prod/v1/safety-report/Safety Report 2018.pdf

What do you think?

I learned from Alexmm about a SMPS designed for the QUASAR and decided to open this thread since other projects may benefit from it.

The schematics can be downloaded HERE.

The first group buy is now closed, but the second one is still open HERE.
If you are interested you can register in English.

I understand from Tibi that these boards should cost around 7 Euros each plus shipping.

Please let me know if you are interested so we can consider the possibility of having boards for all US buyers sent to a single address for redistribution ($aving $hipping).

At this point this is all I know about it. Probably Tibi can help out answering questions.

Cheers!

Bit of a long shot here but I am getting an intermittent fall out of signal when using the AES/EBU OUT into the AES/EBU IN of my Behringer Ultramatch. It would seem that there may be a mis-match or signal overload? The LED which relates to the Balanced In flickers when the dropout occurs. I have only just tried the balanced out on the cambridge. The SPDIF works fine.

As the Cambridge is a very old unit I cannot find any information about it online.

Hello

Dc offset can't be nulled on one side of an Electrocompaniet AWII. If I load the input with a 100K resistor, I can do it. I thought replacing R5 with 200 ohms to have more range with the pot. Here is the front end schematic. There was a service bulletin with upgrades that have been done. C1 and R4 are now replaced with a jumper. C2 is replaced with 1K resistor. Thanks

I bought a EL-34 SEP Chinese amp and was wondering what I need to do to be able to run 6L6s in it as well. I know it can be done, but don't have a clue about what I need to do with pin #1 for the 6L6 and if I need a switch. I have seen an amp that would run 6L6s and EL-34s but it has been so long ago that I can't remember anything about it other than it sounded great.

Thatch

Guys,

Just wondering if there's any real reason why domestic speakers seem to be designed with loads of baffle step and then plonked far from the walls?

I mean, in studios we use flush mount, and in most domestic environments it would make much more sense to mount the speakers on the wall and not have to deal with baffle step...

So are there any other acoustic reasons for this?

I ask because my silly flat has lots of foundation walls with plasterboard partitions, so it makes complete sense to make a "corner wall speaker" that sits in the recess, it's about 15cm deep, so I could have something like 4 4" speakers in there, admittedly the bass would roll off from about 100Hz, but given the environment (i.e. neighbours in a block of flats) that's probably no bad thing... so why aren't comercial speakers more like this?? am I missing something?

I have a Logic 4 channel amp on my work bench that has a blown IC on the bottom of the motherboard.

I have never seen the inside of one of these amps before and I have no clue as to what this IC is that is clearly toast. I am wondering if anyone has any information on these amps. The ICs are labeled on the board as U3 and U6. U3 has obviously seen better days. The ICs are mounted to the heat sink so I’d imagine that they typically run on the warm side and do a lot of work. They are connected across the rails.

Thanks in advance for any assistance,

David

Question for those with more building experience. Working on my first from-scratch SET amp, building is about to begin. I need to drop the filament voltage for my power tubes, it is a little too high for comfort (7.1V on 6.3V rated tubes). Values and whatnot are already determined, going to use a pair of 0.25ohm Ohmite wirewound resistors to knock 0.5V off the 1A filaments.

I am using a Lundahl mains transformer which does not come pre-wired. My question is, rather than connecting the resistors at the tube socket pins, is there any reason I can't solder them directly to the transformer winding pins? That way I'd be able to keep a nice tight twist all the way to the heaters rather than it ending in a pair of resistors at the tube socket.

I konw this is a novice question, I don't see why not but I'd rather ask and than get a surprise 😀 thanks.

H all,
I obtained some 6AV6 and 6AQ5, along with a couple of Altronics M1120 transformers:

Cheap Output Transformers

to use as output transformers (Somebody worked out these suit 6V6 at about 8K impedance). Now I know I could use different (better) valves and transformers, but the fun is to try and use these to make an acceptable stereo amp. I found this schematic:

http://pacifictv.ca/schematics/electrohomehft400-6watt.pdf

which I am using except substituting a pair of 6AV6's for the splitter. I have built one channel on the bench and have semi-reasonable sound from the speakers, albeit it takes most of an iPod output to drive it. I had to add a cap from the anode of the top 6AV6 to ground to kill a 248Khz oscillation, and I only had 3 x 472 caps in series on hand to try. Bass seems reasonable, but it seems to lack top end frequencies and "clarity" (don't know how else to describe it). I assume the cap I added is too large, and will pick up a 220 or 470pF to put in.
I intend on the weekend to try to characterise the frequency response and see how it s actually performing. Will post if I am successful.

Are there any improvements anybody can offer to make this a nice little amp for a small room?
Thanks,
Glenn.

Brief History, skip to next paragraph for real question: I started a small business in a college town selling Tannoy and Klipsch in the 80s. Also worked in a stadium as tech director, lot of experience changing out old horn aluminum diaphrams 🙂. Once I heard the Tannoy DCs I never looked back. My next company purchased a large order of Tannoys to open a dealership in the late 80s. Many boxes have come and gone (System 6/8/10, Ellipses, DMT10) but I have kept the CPA-15s to this day. I have them on monoblocks and have them as my main LR channels. I currently have a set of Arena Center Channels I have collected as my surrounds. I have purchased a used CPA-15 for my center channel. The box was not packed well and the main magnet assembly was cracked all around, common shipping failure. Crossover was also destroyed but I have a good one to replace it with from another CPA.

I am having trouble finding a 3836 driver. I can find a 3828 but I am concerned that it will color the mix. My preference is a 3836/3833 but what other good options would there be? Suggestions?

I have a Rockford Fosgate Punch 800a2 that I replaced some MOSFETs , and my question is it came with 10 mosfets IRF640 five per side and I replaced all 5 on one side with an IRF640N, should I replace the other five 640's with 640n ?

3/4" Tweeter + 6" Mid-Woofer

Scan-Speak Newsletter – Scan-Speak A/S

A while ago I bought a hundred 2SK170BLs from spencer which I have been using on my projects. Unfortunately I don't have time to do as many projects anymore so i am selling the remaining. These are new and genuine Toshiba parts. I have used them in several projects and they work perfectly. I have measured and matched them all myself, so they are guaranteed to work.

Pricing as follows:

- Matched Quad of Toshiba 2SK170BLs to 0.2mA £20 Sold out
- Matched Pair of Toshiba 2K170BLs to 0.2mA £10 Sold out
- Matched Quad of Linear Systems LS74 at 9.1mA (bought from diyaudio store) £30 Sold out

Plus shipping costs.

If you are interested please send me a private message with your postal address and paypal email for a quote.

Thanks

Evan

Hello i want to replace this transistor.Can you suggest any equivalents?
Will KSA1381-D be ok?

Looking for the above board, as I unfortunately toasted mine. Also possible without the SPDIF connection as in the version of DDDac. Must be the newer one which can play up to 384khz.
thanks!

JBL speakers for sale. Unfortunately just one horn.
Condition 9.5/10
Location Norfolk, UK.
Open for offers.
Thanks

JBL 2206HPL x 2 - SOLD

FS: Couple of SSR DC speaker protect modules

2 off speaker DC protect modules.
Solid state relay.
Power up detect with four second mute delay.
Power down detect with mute.
Up to 350WRMS into 4 ohms or 700WRMS in 8 ohms.
£9.99 each plus p+p
p+p is £3.99 to uk and £10.99 rest of world.

Requires local mains transformer 9-0 9-0 2VA or more per speaker protect unit (can't use same transformer for both !)

I have a pair of Jupiter VT Flat Stacked 100v 6.8UF capacitors for sale. Asking price is $110 US dollars plus shipping charges from US 01013. I do not think you can get these caps anymore. The asking price is less than half what they cost. Asking price is firm!

I have owned a Marsh A400 for years. Performance is great but the the remote power on does not work. Does anyone have experience with this. It appears that the company is defunct. Anyone have a schematic for the amp?

Was going to knock up a SE garage amp from 6GV8s I have on hand but I think I may build a Bench Supply first as it will probably come in handy for other projects. Other than the 120V PT for the garage amp I have only one truly high voltage PT. I was saving it for an amp but since it is only rated for about 120-125mA on the B+ winding it might be marginal for a lot of stereo PP applications I may use it for the bench supply instead since one normally prototypes just a single channel and if I do overload it in the bench supply application it would be for a very short time.



The center tapped B+ winding has full voltage tap and a lower voltage tap (maybe intended for screen supply or just for lower voltage option) on the same winding. on one leg of the B+ winding there is also a lower voltage tap for a bias supply. The bias tap is only on one side of the CT. Not sure whether I should use those lower B+ taps to provide a second output for screen supplies or whether to use it for range selection and use a separate transformer to make a screen supply output. Since it is on only one side I would have to be sure that a bias output was not loaded very much to prevent asymmetry on the B+ outputs.

It has a 5V heater winding and a 6V heater winding. It appears that there are three taps on the primary (blue. gray and brown) which I suspect are 240, 120 and 100 (Japan). I suspect I could use any of the primaries to choose different voltage output ranges so as not to over stress the pass tubes but if I do so I would not be able to use the heater windings for the tubes in the supply. Of course the same would apply for using a variac to reduce voltage range.

If I use separate trannies for heaters I could connect the 5V and 6V windings in series to provide a regulated DC heater supply output (max 7V or so).

The chassis has 3 octal and 3 9 pin mini sockets. I figure on using 1 octal for the screen supply output pass tube and the other two for parallel pass tubes for the main B+ output. The 9 pins can be used for error amplifier tubes and bias supply pass tube. I also have a few 9 and 12 pin compactron sockets that fit where the octals are so if I need to I can use some of those tubes for pass tubes.

Possible pass tubes on hand:

6JS6C (1)
6JB6 (1)
6JN6 (1)
6L6 (2 Used)
6W6GT (1)
6LQ6 (3)
6LU8 (lots)
17JM6A (1)
17JN6 (1)
33GY7A (1)
36KD6 (1)
38HE7 (1)
22JF6 (1)

I could start with the 6LQ6s and if they prove to be in good condition I could sell them and use the proceeds to get some other less expensive tubes for this and use the remainder for some iron or other goodies. 😀

As always thoughts welcomed.

Say for construction reasons it was awkward or inelegant to solder a resistor directly up against a valve base, do ferrite beads generally work instead? I see it recommended a lot but I don't see it done often. The valves in question are high GM RF types.

I have some tiny toroidals with (presumably lossy) cores rated for EMI suppression. A couple of turns through them gives a measured inductance of around 10uH at 200Khz. Ideally above a certain frequency, a resistive lossy component would dominate, dampening any parasitic resonances.


Does anyone have any first hand experience with this working, or perhaps even making things worse? Any data points would be appreciated.


My confession is I absolutely hate having unsupported resistors poking out of valve sockets, which are then soldered to a wire. I would love to avoid this in a particular scenario where there is nowhere to secure a resistor. 😉

I got these power supply boards made for my M2 amplifier using PCBway but as you know there is a minimum quantity order, so I ended up paying way more than I would like to admit. I have some boards that I don't need that I am selling to recover costs.

I am asking $20 for each plus shipping.Sold out

They are designed to fit the cases available from the diyaudio store without having to vertically mount the transformer. They fit the holes on the bottom panel as well. They also have AC Live & Neutral lines passthrough for easy transformer connection. They are of course inspired by Nelson Pass's generic power supply design.

If you are interested please send me a private message with your address and paypal email so I can send you a full quote.

Thanks
Evan

Hi!
I am working on a Technics SL-10. I have gone through the unit and have identified a problem with the voltage supply on the MC amp section. I included a pic of the schematic section that I need help on. So the zener is a 9.1V which is supposed to be supplying the base of Q2 with 9.1V but the voltage I measure at the base is 8.2. This is not enough to get Q1 to supply 8.9V to the MC amp circuit. My amp circuit supply off Q1 emitter is 7.5V. I know enough to be dangerous here and I have changed out the zener with no change in the output voltage of Q1. I also changed out the Q2, the caps and 3.9K resistor in the immediate area. I lifted the emitter leg on Q1 and the voltage stayed at 7.5. I am sure my supply voltage is at 12V so that is not the problem. I am measuring about 3.1V across the zener so I know where the voltage is going but I can't understand why the zener is not doing its job and sending 9.1V to Q2's base. Can anyone advise me on what I am missing here? Thanks very much for helping!

Hi,

After getting my SSE running again, I decided to spin-off my thread as I'm looking for commentary on running some of the bigger output tubes with the existing amp design. I have a bit more B+ due to the Edcor PT, and unless I need to beef up the cathode bias circuit R & C, should be set.

I've seen a few threads using the KT120 and KT150 and was curious if anyone has any longer term experience with these tubes. Did they last or did they suffer the same fate as some like the Russian TS 6550's where the getters fade too quickly and they go into runaway?

Also, any comparison between the two tube models themselves? They both should have more headroom and output capacity than the 6550's (and the KT88's I've had decent luck with). I'm just trying to decide whether they will be as good or better than the value priced EH KT88's, as so far they have been the best bang for the buck in this amp both in sound and lifespan.

Thanks!

Good evening
I‘m inclined to go with a ladder type attenuator, but fray off by the steep price tag...
On the other hand there‘s those relay solutions, where the resistor network is On a pcb, connected to a switch, or glasshouse‘s passive pre...
not being electronics-savvy, I ask myself and the community if it wasn’t possible to build the ladder on a breadboard/pcb and wire it up to the switch (24 steps), thus saving on the switch‘s price tag as well as its size? (2 Decks instead of 4...)

Quite possible that I didn’t get the principle, I’m beginner)
Thoughts?
David

Hello everyone!
Has anyone ever thought of an ACE Bass amplifier?

Hello everyone.

Suddenly, i got this Yamaha DSP-E800 almost for free.
It uses AK4324 as a main DAC. Heard a rumor that it can be changed to AK4393 or 96, is that true? I like how AK4396 DACs are playing.

So, anyway, i'm planning to add rear channels to my system with this Yamaha.
Will use it as a DAC from PC S/PDIF and CD S/PDIF output for some time.
And wanted to know, can 4324 be changed to newer 4396 (unfortunately, newest AKs from 44xx series are out of question).

(Also searching for DSP-AX1, these beasts use PCM1704 for all channels, but they are rare as hell).

Hello I need one piece of Dynaudio 24w-75 for a replacement.
Offers for single or pairs are welcome.
Thank you.

I was fortunate enough to score a small handful of these devices.

Enjoy the pictures.

Hello.We have 15000uf 40v Genuine BC Vishay 058 105C LL ROHS compliant capacitors for sale.

BC Vishay 058 15000uf 40v 105C 10.000 hours very long life caps: If you buy 32pcs we can make 3,99USD each plus shipping.Shipping costs 29,99USD for 32pcs worldwide.
Dimensions: 35x50mm
Datasheet: http://www.vishay.com/docs/28342/058059pl.pdf

Do not miss.Limited quantity 🙂
PM me for any questions 🙂
Thank you very much

Marantz 250M Power Amplifier. Amplifier is in need of repair. Powers up but no sound when attached to a working Marantz 3600 per-amp. Exterior is very nice with only two minor blemishes as seen in the pictures. Silk screening still looks nearly perfect on the face plate. Missing one face plate screw. I'm not an expert on vintage Marantz amps but it appears to be a very original unit. The amp was working when place in storage 5 years ago. It could be something simple or more serious but I've priced the amp accordingly if the buyer decides to have the amp fully restored. I'm glad to answer any questions about the amp and test any item that can be tested with a multi-miter.

Amp is on eBay at 495.00 + shipping with no reserve. See eBay auction link for more pictures - eBay Auction

Thanks, Rick

I build a 6- 60 AMP MONOBLOCK .I used as output transformer Edcor 100Cxpp 2.2k.As powertransfo Amplimo 6N536P.Input Ef86 in triode mode then Ecc83 phase splitter and this drives 4 xEl34.The rectifier is a diode bridge out of old PC supply.This is an easy to build amp witch is perfectly stabel good bass and high .Easy to build no exotic tubes .Output power +- 60 Watt .

Does anyone else drop test their builds?

When I build a tube amp (using point to point) and it's up and working nicely, I'll "test" it by tapping the tubes, the chassis, and eventually picking up the amp and dropping it up to 12 inches onto the desk while it's running to check for bad connections (and make sure it would survive being shipped).

Who else does this?

How many of you still use "percussive maintenance"? It's the art of fixing something by hitting it for those who haven't heard of the term.

I am searching for a suitable Sub that could do up to 300Hz at high volume output of 90db or above. I am building new HTS and my design limitation for tower speakers is that the max size of driver can only be 4". 4" drivers are unable to do sub 300Hz without distortion. What can be best suitable Sub which can do up to 300Hz without distortion. No limit on budget.

Hey everyone!

first post, ive been lurking.
im going to get straight to the point!

I am wanting to build a set of ESL headphones and a direct drive amp.
ive been doing some research but ide much rather have a discussion with you guys about it as im a little confused and there really is SO much information to try and catch up on.
basically i have moved away from my wife and home for 3 months for work, this is going to give me some DIYing time. however im reluctant to spend the whole time researching (and it seems i could spend 5 years researching before i start assembling), as then i wont get a chance to actually build anything!

im confident of my hand skills and have experience with electrical circuits of all kinds. (im an avionics engineer, so although i dont work with the intricacies of audio often i understand most electrical and signal, circuit concepts)

im thinking of of basing my designs on the following two designs.


All-Triode Direct-Drive Amps for Electrostatic and Electret Headphones | HeadWize
DIY Electrostatic Headphones | HeadWize

although this is just my initial idea, and i am really wanting your input to help me decide what is going to be the best path to go down.

my initial question.

1/ what is this going to cost me ROUGHLY in parts for headphones and amp. time is irrelevant, and i do have access to cnc machines etc, so this is parts only.
i do have access to a bunch of random parts, but lets assume i have nothing, and am working on a budget (ie i cant afford $240 for apex op amps) im planning on upgrading components over time as i can afford them.

thanks very much for your time.
looking forward to working with you!

I have a pair of LL684's that I bought used from L&L back in 2013.

Used for a while in a DAC back then, but they have been collecting dust for a while some time to find a new home.

Looking for $160 total price, I'll cover US shipping and paypal fees.
Will ship international, adding in actual international shipping cost.
USPS Priority small box to Europe is about $40 as an example.

Randy

It is easy to make volume control if you using build in chip amps. But for discrete class d amplifiers, how we can make volume control after PDM modulation? I saw some sample schematics use volume control before PWM modulation but in my case i use PDM instead of PWM also output voltage of PDM modulation is constant. Simple resistor or r-2r resistor network work on PDM signal?

I'm here on the forum for years, but did not post much of the results of my diy stuff and the all the things i learned by camping arround here.

Today i almost finished a big sealed 77L 18mm birch ply sub for a 10" Scanspeak 26W/8534G000 driver, ment to be used in the corner of my living room. it should give me a F3 of 42Hz and an F10 of 24Hz with a QTC of 0.695 says modelling with the measurements of the drivers i have. Bracing is done with an internal frame and the front baffle is screwed on, but with rubber seals to seal it.

I wanted it to look old so i used a antique trader trick to let new wood look old and this is the result without the driver. I'm lacking the right screws to install the driver it in (wich is painfull that i forgot those). But i already like the rough, beaten up look of the case. It's something different than most of you do, i know, but that is how i like it.

Tops will be these Mark Audio 10M Gen 3 in a 11.5L sealed masss damped lossy cabinet (last picture). All are my own design after years of studying the subject, and experimenting. And a huge part of that knowledge comes from this site, so thanks to all the posters arround here...

Pictures of the finished builds and measurements should follow soon.

For sale i have the following:

Faital Pro 18XL1600 @ £185 - Faital Pro 18XL1600 | eBay
BMS 4552 x2 - @ £90 each - BMS 4552 1" Neo HF Comp Driver | eBay
Faital Pro M5N8-80 x2 @ £30 each - 2x Faital Pro M5N8-80 5" drivers | eBay

All based in London, UK. Can be shipped worldwide.

Any questions, let me know.
Sal