Hi all, and sorry for the rookie vibe I´m going to pass out here now.

Not sure if I hit the most correct category here but here we go.


I have today a couple of HiFi speakers that I don´t have any use for. But would like to try do do something fun with.


I have a small Stereo amplifier with BT.
I want to connect this to one of the two speakers today and will have to mix this into mono. Fair enough so far.

BUT, it would be fun to repurpose the existing speaker connectors on the speaker, making a switch that turns the audio back to its originally stereo and then being able to use both speakers.

Anyone have a schematics or DIY description to how to achive this switch in a good way?

$115 shipped US for 08 -- new or like new
$105 shipped US for 07 -- green dome, new or like new

07 is my favorite dome tweeter, if it matters.
Not bright (I find every dome tweeter too bright), similar too XT25 on the high end, but way way more low end.
08 is pretty good too.

Hello,
I'm looking for the 32 bit driver, is someone among you, who uses exaU2I, would have kept them, because I sent a message to exadevices, they only have the 64 bit version,thank you.
Best regards,
Stefano

Hello everyone, hope all is healthy and well.


So I've been doing some browsing, and came across this: https://www.headfonia.com/2013-spring-tokyo-headphone-festival-impressions/9/


I see that they are typical Cmoy tradition, sticking a headphone amp in a mint tin. But I've never seen something like this before. They appear to be hybrid amplification because there is 1-2 valves/tubes and then an op amp. From a general knowledge point of view, these tubes aren't powered like they usually would at around 200-300 volts, and instead by a couple of rechargeable double A's. Most of the amplification is probably done by the IC. I know that a few years ago a designer that goes by the name of FredsAmps built similar designs to this as a kit on his website, but is now shut down.



I was thinking of building one of these myself, as I would like to know what all the tube hype is about. What do you all think?

Folks,


I was interested in building one of these, but I am a bit overwhelmed when trying to find a good chassis that's a good fit. Can someone help me with a specific model that works well as a chassis for the Whammy?

I am designing a drone to play sound. I can 3D print the horn. Would like suggestions for some light weight PA horn drivers. Any search I do for horn drivers only shows high frequency tweeter drivers. I need mid range for voice signal.

Would something like this work? It is a neodymium speaker designed for portable devices.AIYIMA 2Pcs Full Range Portable Speaker 2 INCH 4 Ohm 16W Sound Music Neodymium Audio Speaker Driver For Computer Loudspeaker DIY - Aliexpress

Or this? TEAX32C30-4/B | Tectonic Round Audio Exciter, 30W nom, 30W max, 4Ω | RS Components

What would happen if we re biased a pro amp Perreaux 8000c with mosfets and huge heat sinks with a view for class A with far less delivered power .It has huge heatsinks .Probably reduce rails .Its a thought in my addled mind.

Hello Guys. I upload this schematic that contains several protect circuits such as DC, overload and clip detect. But the only thing I ask you is about the overload circuit, specially how to calculate R1 and get it to work on the output impedance that one wishes. For example, if there is an under 4 ohm load impedance across amplifier output then the overload circuit will turn off the relay protecting the output stage from low impedance. Varying R1's resistance value, we will get an effective switch off but the formula to calculate this resistor value is unknown for me. Thank you friends beforehand for your response.

Hi!

In many BOM's, parts are marked, like, Rx1 (or RX1)
Have these X a meaning, other than there are options to them?
Are they case sensitive, and a lowercase x means something different than a uppercase X?

Thank you
david

As per the title I am looking for four genuine PCM 1702 SOP chips . If you know of any genuine supplier that might have these chips or if you have some packed away unused please let me know .

These are needed for the repair of a newish modern DAC but so far only supply i can find are all Asian and not too sure if these will be genuine Burr Brown Chips.
So any recommendations would help as well . 🙂

Hi all,
i have a stock aleph 3 in my garage ( still working ) i really love it's look and think of use it again in my main rig for a 8ohm medium/bass driver.
is there a benefit if put my hands on the engine or will it be a "sacrilege" 😀

i was thinking of changing the C power supply with CRC for start.
any other ideas ?

Hi everybody. I have been offered a pair of these speakers at an interesting price. Of course, them being Metaxas, they don`t work, but I hope to be able to remedy that situation.

I`m interested in views, especially from somebody who have heard them.

Regards
RMalmin

There's a TV room in the place I live and the sound coming from the TV is just dreadful. I've floated the idea of adding speakers as a summer project. I've tons of amps around and a small dsp based one (4x 50W@4r) I could use.

I've attached a quick sketch of the space I'm dealing with. It has to stay as is, in terms of positions (I can change the TV furniture though). The problem is the very wide seating with little depth to play with.

Criteria:

- will be used mostly for TV, sometimes for music.
- it has to be relatively cheap.
- no need for high volume levels nor deep bass, for the sanity of the people living just upstairs. Intelligibility is key.
- I've a pair of vintage 12" fullrange I could use as midbass but they will beam early I'm afraid.

If you have any suggestions or ideas, shoot away. Thanks in advance 🙂

To all who want to make a vintage class D Amp .I made this one on the schematic X20 from Sinclair.All transistors.gives good sound it's simplicity.original we're al germanium transistors now simple silicium.

Just wondering why this inductor has leads of different length (I'm only used to seeing this on polarised capacitors). The datasheet doesn't specify.

19R154C | Murata 150 μH +-10% Leaded Inductor, 1.9A Idc, 129mΩ Rdc 1900R | RS Components

Hey there, I am trying to make a tape recorder from scratch. What I want to do is to erase, record and play a magnetic tape. (Now, for the purpose of learning, it does not matter what type of magnetic tape I will use, it can even be a small walkman cassette, but I am willing to make a big 30 IPS recorder/player at the end...)

I also want to make all the circuits myself, like the biasing circuit, op-amps...

Here is my start point, I have made a circuit. I have 2 signals here which are VG1 and VG2. VG1 is my audio input and VG2 is the 100kHz sine signal.



The circuit is simply adding these two signals together. (First op-amp is summing the signals, second op-amp is inverting the negative signal to positive) So my output is signal 1 + signal 2 simply...

I am wondering what is the voltage "play and record heads" use. Because this new signal which will go to the record head should not be more than ...... volts? Can you fill the gap 🙂 ?

I also would like to know how much amplification I need for the preamplifier of the play head? (The signal comes from the play head, and goes to the pre-amplifier. )

Thanks in advance...

Does anyone know where I can buy a new gain pot or have a good part number ?

It’s a 10k pot

Hi All,

I have a Hafler 9505 amplifier I'm trying to debug. As always, I tried finding the schematic and service manual online. Luckily, I was able to find a few files. Not so luckily, the component values don't seem to match the actual unit.

I was wondering if someone else ever repaired a Hafler 9505 and noticed these variation, and if you were able to find the actual (correct) service manual?

Looking online, it seems there are 2 variants of this amplifier. The one with the XLR on the top:
Hafler 9505 Transnova Power Amp | Adam's Gear Garage | Reverb
One with the XLR at the bottom:
Hafler 9505 Transnova power amplifier Photo #1414718 - US Audio Mart
The unit I have has the XLR at the top. I have no idea if the two units have a difference in the actual schematic, but I assume it might explain the differences.

While it is possible to try and debug without the schematic, it typically makes things move slower. Any help finding the schematic/component values of the amplifier I have would be highly appreciated.

Hi:

I need a pair of these to resurrect a Hafler 9130. There doesn't seem to be any threads/sources mentioned recently. I'm very skeptical of the spiffy looking ones being offered on eBay.

Does anyone have a reliable source or a recommendation for modern equivalents?

Thanks
Mayank

Hi! Looking for an already assembled crossover (2-Way 2nd order 8 Ohms 525 Hz). Eminence used to have the PXB2:500, which was crossed at 500 HZ and would have worked fine, also crossed at 600 HZ would have been a suitable alternative, since it is a hybrid speaker (woofer in a vented enclosure and full range driver in open baffle configuration), but they have discontinued those lower range 2-Way crossovers, and now they start at 800 Hz.

Please, can someone point me to a crossover assembler or a company that might have those low Hz crossovers?

In my last design I didn't look to save money on crossover parts. There for I used 14 or 15 gauge wire air core inductors for the mids and tweeter circuits. I did use steel core inductors for the woofers to keep the resistance down. I used mostly Audyn Q4's capicitors. Obviously I did keep cost in mind because I used reasonably priced parts. What I'm looking for is some guidance where I can save a little. For instance can I use smaller gauge inductors for the mids or tweeters? I would still like to avoid electrolytics, just mostly looking at what everyone is doing to keep things smaller and cheaper. Honestly I'm more concerned about saving space, some of these large value parts are hug.

Just finished building an Aleph J with the help of all the good folks here and now that it's done, it apparently has a little more gain than my other amp which uses 45's, and the preamp buzz/hum that it's always had, is now a little bothersome to me and very noticeable during a lot of songs. I'm primarially picking up 120hz buzz but also see a bit of 60hz hum on a spectrum analyzer app.

I've tried the usual stuff on the outside with cheater plug/humx, moving things around, rolling tubes, cables, there are no lights nearby, etc. I do have another couple of rectifier tubes coming thinking that maybe the 5Y3G envelope might help over the regular slender envelope.

Anyway, after poking around inside it looks like the heater wires are all done up reasonably OK after reading that thread here on good wiring practices. I'm wondering about the Hot AC run from the IEC to the switch and from the switch to the transformer. While they're both live, they are running in opposite directions, should I twist those? The rectifier filament wires are twisted, but could be one or two turns tighter, should I bother? I have a hard time thinking this is the cause. Same on the rectifier plates?

I've noted that the main power switch and center 6SN7 base arent grounded. There's also a bit of daisy chain going on with connecting all the grounded points together at all the distribution strips. (what's the proper term for those?) Seems like a high chance for a ground loop; I'd like to attempt to fix it but a lot of things are glued/potted to the chassis so it will be hard to get at everything.

Another person with this amp noted they created a ground clip that they attached to the preamp chassis to their source that killed the hum dead.

Any other thoughts? Am I thinking right here? Have been trying to get in contact with the builder without any luck unfortunately.

Just impulsively picked up a 7L5 module for my old 7000 series mainframe (got one at a decent price). I tend to do heavily distortion amplifiers for my personal projects and work so, an asynchronous analyzer won't go as far as it could.

The Option 25 or 30 is what I'm hoping to pick up. Willing to pay whatever anybody would ask if they have one they'd like to part with...the 7L5's can be sold off on their own fairly easy.

I have a Devinyliser driving the subs in my system.I built this from the Signal Transfer Co kit several years ago.
Now I need to adjust the gain of the output unity summer.
I have lost all the kit paperwork , and need the list of component values referencing the circuit board stuffing numbers.
Anyone got that kit paperwork to hand.
STC arent answering at this time.

Hi all,

I have just bought a new Edifier S350DB speaker. But in some songs, my subwoofer emits some strange sound like rattling sound.

The first song that I played "Infinity Ink - Infinity (Dubdogz & Bhaskar Remix) (Bass Boosted)"
YouTube

The second song: "Imany feat. Filatov & Karas - Don't Be So Shy"

YouTube
Does my subwoofer have any problem?

Thanks!

hi guys
if anyone in the uk has original rotel transistors, then please contact me.

many thanks
gaz

Hi, I am new here. Name is Tazz...

I have gone on a wild adventure to build a DJ mixer. So far so good. I have a main board with multiple balanced outs etc... Part of this PCB is a headphone section built on the LM386. I know I know not the greatest chip...

The headphones actually sound pretty good. But the problem is when I touch the pot or the cable or the caps of only the headphone section I get EMI or loud screeching sound. This only happens at this section the rest of the PCB is fine...

The PCB has and uses 100% ground layer...

Here are schematics pictures of the PCB. The problem capacitors are c21 and c22. If touch those we get the loud screetching sound. If I put the pot on the panel of the case and close the case, the case transfers the EMI to the headphones. Touching the jack of the headphones doesn't affect it nor the rest of the circuit.

Before I go down the route of redesigning PCBs just wondering if some insulation techniques could work.

Dropbox - mixer-files - Simplify your life

Hi,
I'm in the process of building an integrated amp with an Aleph J and BA-3 front end. I am planning to power both off of the 24V Universal Power supply, using a 18v/18v 500VA transformer.

I want to add the following remote control ladder attenuator, which appears to require 5V/1A.
High Quality Audio & Industrial Attenuators


What would be the easiest way to power it? Am I going to need to try to fit another transformer in the case?

Much Appreciated!

hi,
I am looking for semeone who can help me create a step sequencer.

here is a description of the initial project,
I am adding some functionalities so it will evolve a llittle from this but basically
it will have 9 pads 1 switch for selecting items and 16 pads for note/key selection on the sequencer pad
1 usb output

the sequencer will be of a size a little bit smaller then a computer keyboard
with a row of trigger pads like on the tr808 drum machine, 16 pads,
above these pads will be a row of 8 buttons to assign sounds.
A tempo adjustment knob a usb out plug one led to show tempo

The sequencer might have midi implemented but the first and main system
is with computer keyboard keys, with numbers, so basically i would like to be able
to choose a number like 1, assign it to steps the 16 pads, then choose the number 2 and assign also, etc…
so it will be sending through a usb cable a rythm pattern with numbers (following a choosen tempo)
like: 1…2…1…2…,
so I can send this pattern to different apps like an online synthesizer.
numbers can be choosed and all the letters on the keyboard as well.

So as you can see it is not a very complicated project but it does involve some knowledge
with programming.
I would like to see your previous projects and
get this project on the road.
thank you

I recently started reading a bit about the folded/shunt cascode (thanks, Rod Coleman for your interesting posts). It's a cool circuit and I have a potential project for it as the differential front end on a push-pull amp (Allen Wright style).



I understand the basic workings and am comfortable enough to be able to calculate bias/dissipation/etc as a single-ended cap-coupled amplifier. However if simply mirroring the layout in a LTP arrangement, one runs into CCSs on top and bottom of the circuit.

Notwithstanding Morgan Jones, this is usually frowned on. But in the case of the folded cascode, I wonder if the multiple CCSs are an issue. My thinking is that surplus current is driven through the shunt anyways, and so CCS current differences at anode or cathode (with respect to the tube) are ok. Thus the two CCSs would not simultaneously be trying to set a different current. The cathode CCS sets current through the triodes and the anode CCS sets current through the triodes and the shunt.



Has anyone tried this kind of circuit as differential? Maybe a current mirror instead of a CCS would make a good anode load, too?

Hi,

Am looking to build a cable for NAIM NAP 150 that I plan to use it to drive center channel. The ones that are available are DIN to 2 RCA cables. Am thinking Mogami 2549 and Amphenol RCA but not finding the 4 pin DIN that is for NAIM. Anyone built one and where to buy. Also should I connect positives in 4pin together? The center channel is Bowers which has two binding posts so will drive 50W 2 channels to HF and LF posts. Thoughts?

WTB: Sanken & Hitach & Sanyo

Sanken 2sc2581 / 2sa1106 - Hitachi J77 / K214

Sanyo 2sa 1210 / 2sc2911

Any quantities you might have

Thanx for looking


Regards
David

If you were to build an enclosure that was flat to 20hz for 2 18s what alignment would you use. The drivers have 22mm xmax.

Hello!
Anyone has tried voltage doubler for big triode like 211 or 845 and operating around 1100v??


Any pros and cons with voltage doubler rather than conventional type high voltage with full wave rectification?


Thanks!

Hi guys,
A while back I picked up a Symaudio P-200 Mk II pre-amp that needed repairs. With all the free time I have available I decided to try to salvage it. As you can see the power supply wiring was stripped. I jimmied power into the pre-amp and apart from a few problems it seems to be working fine.
(Maybe more to come later???)
I would like advice and or opinions as to how to make proper connections to the power supply. I suppose I could just attache the power cord to the 2 black wires of the Toroid (thru the fuse) and be done with it.
Voltage in is 120Vac & out is +20Vac & -20Vac.
From the picture:
the yellow & orange wires go to the bridge rectifier on the PC board.
one black wire goes to one end of fuse
one end of the power chord would go to the other black wire from the Toroid & the other one to the fuse.
on the side of the case to the right of the toroid is a ground lug with no wires.
I'm presuming that the power chord (which was not included) had only 2 wires, i.e., no ground wire.
So the question is: How best to wire this pre-amp. should I use safety caps, what connections should be made to the ground lug, etc., etc.
Any and all opinions/advice will be greatly appreciated.
Thanks
Fred P.

Does anyone have a schematics for plug shunt filter like istoek EVO3 isoplug or PA audio noiseharvester .....?

I have one Audison vrx 4.300 without any sound.I don't have any alarm or protect mode and i have also HV rail alive.
I need electrical diagram/similar or some clue because is very difficult to troubleshot this.I will upload some pictures from inside.

Sonore Async USB-I2S, DXD/DSD interface with onboard OSF

Hey folks, I wanted to introduce the new USB-I2S interface for DIY DACs from Sonore.

Features:

44.1-384 kHz capable
DSD 64 and 128 via DoP (4x and 8x DSD may be possible via ASIO native)
Asynchronous USB operation
Complete galvanic isolation from the serving computer
Ultra low phase noise oscillators: Crystek CCHD 957 Series
Output on micro BNC connectors for u.fl cables, and solder pads for direct wiring.
I2S and DSD output multiplexed to suit ESS based DACs
Advanced, onboard 8x oversampling filter using proprietary digital filters


For ordering details go here:

SONORE USB Interface

And of course, further discussion is encouraged here.

Hello I’m Gary,
I’m new to the forum and also to the world of home cinemas!

I don’t have a clue what to do but, I want something set up in my bedroom , I can run cables in the loft and get a speaker to each corner of the room and even get the cables down the wall to potentially be behind my tv.

The only thing I don’t know if that’s the way of doing things?
The Tv will be used for watching movies and general tv and playing my computer so would love the sound to be all around my room.

can someone point me to the right equipment, I don’t want to spend loads at all. After all as it won’t be used all the time maybe a couple hours on a weekend.

Thanks

Gary

I've been lurking on here for a while and this is my first post and first speaker build.

I have decided to build 5.1 system using the Digger 8 subwoofer and Helium micromonitors.

I decided to make a downwards firing design and to fit a fabric cover over the PR which also wraps around to the front.
I planned the build using Solidworks.





Bought a Bosch router and a cheap version of a Jasper circle jig which seems to work quite well.

I didn't cut the panels very accurately or get the panels lined up particularly well so there were some gaps which I filled and sanded using car body filler.



Added the washers to the PR and assembled it all. It sounds good so far.



Waiting for the cloth and teak veneer to arrive now.

.

Would a classic 47 headphone amp make an effective buffer for the input of an IcePower 50ASX25E? (Schematic for the 47 attached) My input sources are literally Schiit: Mani or Modi into a Sys for switching and volume control.

Hi,

Looking for ScanSpeak D2905/9900 tweeter pair (new or used but in good shape).

Thanks,

What does time alignment, Infinity Kappa's, an NVX pocket amp, and a horn subwoofer sound like? Have a listen below:

YouTube

I bought an Isco Model 453 the other day and there is no information on the net about it. I mean nothing. I hope someone proves me wrong. Anyway, couple questions if you personally know anything about it.


1. What type test leads fit best
2. Can you short the + and- to set current (mA) knob.


Thanks in advance.


tk

Recently acquired Trio (Kenwood) vacuum tube audio generator on Ebay. Did a Google search for schematic and got zero hits. If anyone out there has this information it would be greatly appreciated. Thanks.

I have a conventional stereo set-up with an N-core class D type amplifier and electrostatic loudspeakers. The output signal of each amplifier channel (some 40 Volts max) goes into one loudspeaker and there into a transformer that transforms it up to a few thousand Volts. Then the high voltage signal goes to the stators of the electrostat. Nothing abnormal, all as can be expected.

I am wondering if it would be possible to bring the transformer out of the loudspeaker and in to the closed loop of the class D amplifier. The primary coil of the transformer would act then as the low pass filter of the class D amplifier. The loop of the amplifier would be closed by connecting the secondary coil through the / a loop-filter to the input of the amplifier.
In a momentary lapse of reason I even throught of replacing the normal transformer by a (cheap!) fly-back transformer.

More in general: does somebody knows any high voltage class D amplifier designs?

I am building a Home Theater sub woofer. I would like to go with an 10 or 12 inch driver. I don't have a whole lot of money so i was looking on eBay at Klipsch replacement sub drivers. Then I discovered that kicker makes large sub drivers for cheap. I assume that there is some bad side or maybe it is just bad for home audio? Any help would be appreciated! (FYI my budget is right around $60)

Thanks!

Hi all, I figured that I would start a new thread ref. This issue, as I received a PM about it today. The original thread is ancient history so I’ll come clean here.

A while back my Heath AA-141 preamp decided that it needed a new power transformer and I found myself with few options for replacement.

I found a suitable replacement in a toroidal transformer made by AnTek
. The part number is AS-05T120

I can’t remember how much it cost, and I don’t know if they are still in business.

antekinc.com

It had two filament taps if memory serves, and I only needed one, so I tied them together in parallel.

I read on the wiki that it is best to use the impedence of a speaker at its xover frequency not its nominal impedance.. so in the case of the Audax ap17ozo its nominal imp is 6 ohms... its impedence at the crossover frequency I'd like to use 3000hz is 11.6 ohms... I will use it in a 3 way setup and that would be the high crossover.. now my question is if I put in a zobel network to control the impendence at high freq... and if I calc correctly.. Rz is 1.25 x Rnom = 8 ohms.. and the cap is Le/Rzsquared = 11.6 uf.. will this effect the speaker impendence at 3000hz?? in effect knocking down the 11.6 ohms impedence with the zobel network installed... that is what it is for.. right???

Bud

Hi, I'm planning to build two 3-way active speakers that will be mounted on the family room wall for listening while standing, mostly when in the kitchen. I've built 5 speakers from kits but can't find a kit that will work for this difficult setup--I also want to try building active. Since my source will be Spotify I've settled on the nanoDigi so I need 6chs of dac and amp.

My question is: how I should divide my budget between the dacs and amps to get the best sound? I'm thinking I should get the best dac for the tweeters, something in the middle for the midrange, and save money on the woofer's dac? I figure the higher frequency sounds are harder for DACs to do well.

For the amps it might be similar but with say 500 lower quality watts for each woofer, say 100-200 for mids and 50-100 for tweeters?

Any suggestions on brands is most welcome. I plan to spend around $1200 on the drivers so I figure $1500 for the other components to get the best bang for my buck? Given a relatively low quality source I don't want to go crazy on the component cost/quality.

Any guidance / thoughts would be much appreciated.

I recently was given a Stage Classic TG-10 practice guitar amplifier. The amplifier circuit board is a pre-amp plus a single transistor (?) for the output stage. The pcb has the following info printed on it:


I'm thinking of re-purposing/using the preamp board and was wondering if anyone could provide some information about the board eg. schematics, expected power out, wire harness colour coding, etc. TIA

I am having a big issue with the solid state guitar amp i built. The pre amplifier is from the dean markley k-20x and the power amp is the TDA2040 30W amplifier. I am reading 15.5 to 16 volts dc on the positive speaker output and -15.5 to -16 volts dc on the negative speaker output (those are my power supply voltages).
I have desoldered the jumper wire that connects the pre amplifier and power amplifier so i know the issue is there. I have also checked every single resistor and capacitor in the power amplifier and checked my board design again.
I noticed only the positive side TDA2040 appears to short and heat up and when i switched it for a new one and turned the amp on i was able to see the voltage quickly rise to those 15.5 volts on the oscilloscope(then it just stays on that value). Also when i desolder the shorted TDA only pins 4 and 5 (output and V+) check for continuity(these pins measure about 30M ohm on a brand new chip), and the rest of the pins seem okay. The negative side TDA2040 seems okay too.

I attached the power amp schematic below.

Id love to hear your opinion on this. This is for a final year project and im getting desperate.
I start to regret not having done a little arduino toy like the rest of the class instead of a real eletronics project.

P.S- I did not put any isolation between the chips and the heatsinks because I didnt think that would be a problem. Please tell me if it is. The two heatsinks are separate from each other and arent touching anything else.

Double P.S- Im using a 12-0-12V 80VA transformer with a BR356L rectifier and two 2200uF/25V capacitors as my power supply

Hi All,

i've been planning on building an analog dj mixer for a change. I've build various midi mixers, but like to get back to analog mixing. Buying is an option but not the fun route so that's why.

the E&S DJR 400 has caught my eye and the basic volume mixing wouldn't be a problem, an active 2 band EQ is not that hard either.

The problem would be building the Isolator. I've been searching all day but can't find any proper schematic with explanation.

Could one of you guys point me in the right direction?

here is a link to the example mixer

Hi Guys, I have not been designing or building speakers for some 5 years, but with the quarantine in Puerto Rico I have plenty of time in my hands, so I have fixed some speakers that I had laying around, I started building outriggers for a pair of TABAQ which sound great, but due to my lack of woodworking skills then, one of them is a little tilted to the side, which will be leveled by using outriggers. In the process of building a Class D 7 channel amp for HT duties, and want to build a Push Pull EL-84 amp (if someone can direct me to a simple, but good, EL-84 plans so I can build it I will appreciate it).

Anyhow, not gonna keep boring all of you with all the work I have done around the house and in my vehicles, plus all the cooking; going into the 7th week of quarantine.

Some time ago my cousin had given me a pair of tweeters to do a DIY project with. I had put off designing a speaker to use them in, it's time to do something with them.

Can someone suggest a woofer or mid-woofer to go with a Hiquphon OW-1, or a speaker design that I can use it in? I understand it is a very good tweeter.

My woodworking skills have gotten much better over the years and I have a 1/2" MDF panel in my garage begging to be used. Thanks in advance for your help.

Hi all,
Has anyone got a Mark Johnson Quasimodo built up and working that they aren't using and wish to shift? I have a need and would prefer in this instance to not take on yet another project but rather just get the tools to complete a few and (hopefully) clear some desperately needed bench space! However I need this to systematically quieten down some unruly transformer ringing so if someone has a PCB gathering dust I will very happily consider it if nobody is selling a complete unit. Please PM if you can help, I'm in UK for shipping.

Thanks in advance, and kaló Pascha

I know people already tried rock wool but specificaly the Safe N Sound brand product?

Also who compared the effect on mid frequencies and low-mid frequencies?

Specs here:

https://cdn01.rockwool.com/siteasse...fing-Insulation-Techdata.pdf?f=20190515124445

Seems to be more efficient starting from 250hz according to that sheet, but what about twice the thickness (6'') ?

Hello,

I recently acquired two Tymphany NE265W-04 Woofers hoping to build a 3 way floorstanding speaker. Has anyone used these in such a design ?

Thanks

Hello,

I m doing a diy circuit to make a battery power supply for my portable cdp used as source for my home system.
The question is about the differences in quality sound I can obtain with different battery technologies....
A well reputed CD tweaker told me several years ago that traditional lead acid ones sounded better than gel ones...
Lastly somebody told me that he had very good results with lithium polymer ones...
Did you have advice about it?

Thank you: David

These are about 6 months old, used a little, not sure how many hours but less than 200 for sure, probably less than 100.

They are the UltraSonic SS type:

One UltraSonic SS-30, fits 6SN7 and equivalent size.

Two UltraSonic SS-9, fits 12AX7 and equivalent size.

$30 shipped in the continental US for all three.

I am cytowing on eBay with 594 positive feedbacks, never a neutral or negative.

Thanks.
David

Hi!
I've planned to build a tube preamplifier according to this:
Linear Audio | your tech audio resource
It's a low voltage design witch I think is a good starter project for a beginner like me.



My plan was to use 6922 tubes and GZ34 rectifier. Rp1_ohms = 87 K and Rp2_ohms = 26 K.

For a power transformer I was planning to use this with its 45V tap:
https://www.lundahltransformers.com/wp-content/uploads/datasheets/1683.pdf
and this choke:
https://www.lundahltransformers.com/wp-content/uploads/datasheets/1685.pdf

I did some calculations in PSUD2 and if I use the transformer 45V-tap and rectify it in GZ34, parallell 20uF capacitor, series 17 mH choke, parallell 100uF capacitor, series 17 mH choke, parallell 270uF capacitor --> B+.

What do you guys think? A resonable approach?

SOLD - Octal Mono Aikido w/Regulated PS

These are GlassWare PCB's fully-populated and tested. The power supply is a PS-1 with Audyn film caps set for 300V B+ and 6.3V heaters. The driver boards are Octal Mono Rev. E set-up for 6SN7 tubes with Audyn PS film and 1.5uF Obbligato Gold coupling caps. Gold ceramic octal sockets on back side for through-chassis mounting.

This preamp has been assembled and tested. With a quad of Sylvania Bad Boy tubes, this was the most transparent and dynamic line stage I think I have ever heard! It is just WAY TOO much gain for my system!

Comes with both PS-1 and Aikido User Manuals.

$250 for everything shipped to the US. International contact me for shipping costs.

The Thorens TD125 used a Wein bridge oscillator to drive the motor, firstly using discrete components and then in the Mk2 709/714 op amps.

With the top-end TD320 they used an RC oscillator (schematic attached). However I am puzzled by this circuit. It seems to most closely resemble a quadrature oscillator using the two top left op amps. However a quadrature oscillator requires 3 RC segments whereas this only appears to have 2 ( consisting of the 1% toleranced caps and resistors, I assume).

Can anyone explain how this works please?

I built a tri amp two years ago with three separate power supplies, one for the base amp, one for both mid and high frequency amps and one for the controls, filter and attenuator. This took up a large cabinet but works fine.
I intend building another tri amp with all the amps using discrete components due to obsolete chips. The power supplies for this tri amp would be separate for each of the amplifiers and a fourth ps for the controls, filter and attenuator.
The space requirements would mean a very big cabinet.
My question is - could switch mode power supplies be used without creating interference problems. I have never used a switch mode ps and have only read of the interference problems with them in the past.

I have a simple question that's probably been asked and answered before (I tried searching but couldn't find it)

Can I connect two outputs on my carstereo to one speaker? For example in my 2-door (and 2-speaker) car, can I connect the front+ output AND the rear+ output to the speaker's + input (and same with the -) on each side/channel, to utilize my 4 channel stereo better?

And if so, what happens to the audio signal? In my mind it shouldn't affect the audio signal at all, but I could be wrong.

Looking for a pair to build a line stage.

Jim

My build so far.
I am going to use the same chassis JY used in his build.
Waiting patiently for Antek to have some 3218s back in stock to get an idea for layout.

Finally rounded up the gear for dedicated podcast recording. While not exactly PA or live sound, some setup aspects remain similar. Take a peak:

YouTube

I have the BrianGT mini Aleph board set and would like to build an Aleph 40: 8 output devices, 6 on the output boards, and 2 on the main board. Yes, I know this will make the enclosure more challenging, but I have some ideas.

However, I have some questions. Sorry if these have been asked before.

1) The parts list I found says the bias resistors for the output board should be 0.47 ohms, but the schematic I found shows them as 1 ohm. Which is correct, and is this also correct for 8 output devices?

2) I don't have ZTX450/550, but I have BD139/140. Can I use these?

3) I have lots and lots of IRFP044. Any issues using these? Can I turn up the wick with these? How?

2 of these I want to buy....

Hi,

I'm looking for help in understanding the circuit design for the Haffler DH220.

First, a bit about me. I have a degree in physics and did some electronic labs in college, but I'm not an engineer and that was 20+ years ago. I do some electronics hobbying, mostly fixing broken stuff, but don't have any experience in audio projects, though that seems to be a hobby waiting to happen. I've good analytic and mechanical skills. I work as an IT Architect and restore motorcycles as a hobby. All this is to say that I think I'm up to the task of understanding this, but I could use a little help.

I have a working amp that I want to refurbish as it sounds a bit "dead". Not dead like it doesn't work, but just not very open, vibrant, etc. My thought is that I'll upgrade capacitors and replace components as needed based on testing them.

However, rather than just jump in, I'd like to have a solid understanding of the circuit first. From studying the schematic (posted below with my markup), reading literally hundreds of posts on this and other forums, reading appropriate sections electronics texts (The Art of Electronics, and Sloan's books High Power Audio Amplifier and Audiophile's Project Sourcebook), and reading through Marshall Leach's description of his amp design (very helpful), I have a pretty good high level understanding of the Haffler design. However, there are some sections of the circuit I don't understand.

What follows is my understanding (please correct any errors) as well as my questions.

The design follows Lin's 3 stage architecture. It is a complementary design, so in the following (and in my markup of the schematic), I'm just going to focus on 1/2 of the circuit

The input impedance is set by R1. The input is ac coupled through C1 and C2.
C21 and C22 are to remove any power supply ripple.

The input stage is a differential amplifier formed by Q3 & Q4 with a current source in the tail formed by Q2, D4, D5, D6 and R9.

The input stage is biased by the voltage divider that is adjusted by P1.

Output from the input stage is from the collector of Q3 and feeds the 2nd stage (the VAS). The 2nd stage is a Darlington Pair (Q7 & Q8). Diode D9 seems to work like a Baker Clamp to protect Q7 from saturating. If I understood my reading correctly, a Baker Clamp would have another diode, so I'm not sure if this actually is a Baker Clamp or not.

The output of stage two is from the collector of Q8 and feeds the base on the output driver Q12. Q12 is biased by the amplified diode formed with Q9, P2, and the associated resistors. Q12 is configured as an emitter-follower and the emitter output feeds the parallel MOSFETS that complete the output stage.

The output is run through some filters composed of L1& R36 along with R35 & C19 and R37 & C20 (I believe these two RC segments are part of a Zobel network).

Questions:

How is this 2nd stage biased? Is it through R9 and C4? If not, what is the purpose of R9 and C4?

What is the purpose of R34 and C18? My guess is that R34 is part of the feedback network and C18 provides a mean to bypass R18 for certain frequencies to adjust feedback.

The circuit near point A in the schematic is the feedback network, correct? If someone feels like explaining how that functions, that would be great, though just knowing it is the feedback network is enough for my general understanding.

What is the purpose of C23?

What is the purpose of C11, C12, and C13? More power supply filtering?

One of the output stage input drivers (lower part of diagram) has some capacitors in it's circuit segment (C10 and C17) that the other driver doesn't. What is the purpose of those and why on only one driver?

What are the diodes in the middle of the diagram for (D11, D12, D13, & D14)?

Finally, can someone explain the purpose of the Resistors and Capacitor (R401, R402, and C401) in the output stage? Are those there for biasing? I'm having a hard time wrapping my head around that detail.

Thanks in advance for your input on this. If I get a thorough (and accurate) understanding of the circuit, I'll write it up and repost it.

James

I need some info regarding replacing the output transistors. I realize finding original replacements is not going to happen. I have purchased a pair of IRFP9240 and IRFP240 after reading some threads about this amp.

I need to know if I need to modify anything else inside to get these to work. Also should I replace both channels with the new parts. I believe that one channels original outputs are still working. So do I need to replace both sides?

I did try and install these new parts on the dead channel. Everthing went OK I thought. But as I turned it on and try to adjust the Bias I am getting 0.0v on one side and the other seems fine I can set it to the 65 mv the service manual asks for.

I have done many tests to see where I am getting voltage. Or for short resistors. I found a couple that were out of tolerance and replaed them accordingly. Voltage is making it to the main board. On the side with the original outputs. My measurements are not to far off the required values. The other side gets voltage but nothing across the emitter resistors. I cannot find the short. Please help

I am not looking to send this out to be fixed by a tech. I want to do it myself. I do have some knowlege in electronics but I am not a tech or professional. Please anyone that can help me I greatly appreciate it.

Do I need to look at the driver board? Or main board? or other mods to get these outputs to work.

The amp's tubes both light up. I really like this amp. Please reply.

i have for sale four lt3042 double power supplies (picture has 5 but i sold one already), ideal for dacs, clocks etc. they are good, just need transformer and are ready do power!
2x5V and 2x3.3v lt3042 doubles power supplies.

asking 45 euros for all, including shipping in Europe.

😱😱

I've been looking everywhere for a service manual for the Wavetek 146 generator, but have had no luck.

Sort of throwing a Hail Mary if anyone has come across a circuit to jazz up the front panel of a piece of equipment? Sort of like a front panel LED that doesn't just stay solid, but pulses to output power, or pulses to music, etc? Thinking that must have been used some time some where on a commercial piece of gear, maybe even just an elegant application of a special purpose IC.

I know you can rig up a simple transistor circuit to act as a single LED to pulse with signal, but doesn't seem like a good solution, as setting would only work at one volume unless there was AGC as well.

Hi All,

Just a quick question about my Sharp stereo amplifier model SM-1122.

I was in the garage listening to the radio using the Sharp model ST-1122 AM/FM stereo tuner when I heard a loud POP. Immediately there was quite a bit of hiss/static along with the music, similar to when you get this analog tuner close to a station but not really on it yet. I walked over and looked at the tuner signal meters and they were close on but I adjusted the dial anyway. No help.

It's an old set up and I have used DeOx on the switches and buttons once about 3 years ago. So every once and a while I have to cycle thru the buttons on the tuner (AM/FM, mono, air check) to fix little issues. I cycled thru the buttons on the tuner, no help. Then I cycled thru the buttons (loudness, mono)(phono, tuner, tape, aux) on the amp. No help.

That's when I noticed that no matter what source button I selected I now had a constant loud hiss that is not affected by the volume control.

Has the amp finally given up the ghost?

R/
Jim

Any idea's, Dynaudio issue

In 1991 I built a pair of Dynaudio Twynn speaker with Dynaudio 17 W-75 woofers. Over time, (in the past three years) the top drivers (mid-range speaker) on both pairs has started to rattle with music that has heavy base or if I play them a little loud. I am guessing that the voice coil is bad. Any feedback on if you think that is my problem?

My real question is;
Can I get them fixed? If so at about what cost? and by who?

Or;

What is a good replacement driver for the Dynaudio 17 W-75's that would work with my Dynaudio Twynn setup and be as good or better than the Dynaudio 17 W-75's .

Thanks for the help,
John..

I have one of these in for repair .

The SJE2889 can be replaced with 2N6488 correct ?

Also do I need a bridging module or what do I need for the input

They are din connectors so wondering if I need a module or din to rca or does anyone have a module I can build for this ?

searching pair LL1668 choke in 10ma or 15ma gap 🙂

Hi Y'all,

Maybe someone out there has a something like a Dell Laptop with
win7 on it that they aren't using any longer. I need one so that I can use
my QA400 analyzer through it on a USB2 port.
charger that works etc.

Probably needs the 8MB RAM and whatever video memory will
work. The larger the screen the better.

QA400 doesn't work on WIN10 machines.
It worked with WIN8 but that is problematic.
with WIN7 it worked just fine.

PM me with what you have or post a pic here etc and price.

PS - I'm on a very limited budget.

Open to trade for tubes or for sale.
Matched NOS Pairs:
7581A NOS,NIB Philips ECG7581A for reference only ebay $429.99 LINK
Mine are triple matched, factory, distributor, then in actual amp. I'd let these
pairs go for $325 plus actual shipping. While they last.
Gm = 4700, Ip = 50
Amp match varies a bit as it's not as controlled
as a precision matcher. These voltages were measured
through a 10 ohm Dale RN65 to ground and subsequent
extrapolation to current draw at 450V if I recall.

Tube were burned in for approx 30 minutes to stabilize,
then also checked for noise, and microphonics by chopstick
testing. I guarantee these tubes!

5 - .439 = 43.9mA
6 - .420 = 42.0mA


7 - .426 = 42.6mA
8 - .404 = 40.4mA
9 - .419 = 41.9mA
10- .423 = 42.3mA

The only non-performance issue that I noticed with
these tubes is they've been in in-home storage cabinet
and each tube has been protected with a green puffy
styrofoam peanut. They exhibit a slight fog on glass
appearance that I wiped off the two tubes in the pic.
Along with the very gentle wiping, some of the green
logo edges started to lift also.

6V6 GT NOS Mazda "Guerre"
This pair only, $125 plus actual shipping

Gm = 26.0, Ip = 3.10
Gm = 26.0, Ip = 2.90

Cheers,