1 dimension has to be 13" or less.
Other dimensions don't matter.

Got my speakers done, but not sure I will get to putting an amp together.

Having not been able to cure the display problem on my CDP-CX350 due to unobtainable parts, I have been exploring other models. It seems there have been several that are outwardly identical and that play 300 discs. Does anyone know what actual differences might be between mine and say a CDP-CX335? There were at least four different models capable of playing 300 discs at widely differing price levels. Any Sony enthusiasts out there?

could somebody help me make an amplifier that utilises these mosfets?
i dont want to buy any more parts and i have enough small signal bjt's and other discrete components to do it.
im a dum dum and i dont even know how to bias the dumb things.

Here is a a C Audio RA3001 fixed. Stuck in protect. Two MOSFETs blown on Channel 1 and also three small signal transistors shorted.

- Checked all fuses. .. all fine.
-Identitified blown MOSFETs on channel 1 , removed them. Measured as a resistors! Shorted and not open!!

• Pull out the rail fuses for both channels.
• switched back on via dim bulb, still stuck in protect..
• start checking all the signal transistors and diodes, visual check on board too, this takes time and concentration not to miss any...found three shorted transistors (One was a full short across all leads)
• replaced transistors, checked and checked again, fired up on dim bulb. Comes out of protect , hooray.
• drain filter caps, insert fuses, fired up and all fine and out of protect still. Just need to replace the two blown MOSFETS.

-DC offset under 10 mV.

BF423x2, BF422 and two MOSFETs blown.

Not sure what would cause all this to blow like that!

Pic is with three MOSFETs taken out. One was good though.

Dear audio enthusiasts,

I am new on the forum, and generally new to audio related stuff. Since I'm doing something like this for the first time I'd like to ask for some help in designing and building a small waterproof enclosure for an outdoor speaker. This isn't your typical audiophile project, but more like a simple DIY hobby project of mine. I'm building a small audio device with a single speaker (mono) that will be installed somewhere outside, most likely up on a tree in an open field. The device will periodically play various animal sounds like bird songs and the like. It will be solar-powered, so I will probably want an efficient design to convert maximum amount of energy into sound. The electronics and the PCB are mostly finished - there's a solar battery charger, there's a microcontroller, there's audio data storage, and there's a class-D amplifier IC on the board. I just need to wire up and stuff everything into a box.

I'm having some trouble understanding how to build this box. It's supposed to be waterproof, so wood is likely out of the question. It'll probably be PVC plastic or maybe epoxy/fiberglass, but that's not the main issue. What I'd like to ask about is the shape/size of the box. I've already tried building a test box like a small closed enclosure, but the sound coming out was heavily distorted with some hissing. It sounded like the lower frequencies were more pronounced while the higher frequencies have been cut as if the box acted like a low-pass filter. Then I tried the same speaker with a simple dipole (a plywood board with a hole in the middle), and it worked wonders. There was nice clear sound with no hissing at all. Also, opening the former box did help plenty with the sound quality. Now obviously, I cannot use a flat dipole board directly since it's not waterproof, but I am guessing I will have to use something that is opened on both sides of the speaker to maximize loudness? I also don't want it too big as it's going to be a pain to mount on a tree. Bass and lower frequencies aren't really an issue for this project.

Any suggestions how I should go about?
The speaker I'm using is this one (12 Watt): https://www.cuidevices.com/product/resource/pdf/gf0876m.pdf

Thanks in advance!

Has any member encountered such a fake socket? Two pieces of brown Bakelite sell for $13 to $18 online. From some pictures, molded markings showed foggy and unclear. That's likely NOT to be part of the CMC tradition. If you have relevant experience, please share your views. Thank you for your opinion.

Rather than continue and extend a fragmented discussion on other threads, I'm starting a new one to discuss my amplifier design, the AMP-70. Fast slew rates are desirable for audiophile amplifiers, for better transient response. My 1000V/us amplifier, which can deliver 100W rms into 8 ohms, could be thought of as an awesome hi-fi amp, but it's really just a laboratory amplifier designed to deliver a full output swing up to 5MHz, even into capacitive loads. (I've included some reduced-size images in this post, the full versions are in the Dropbox folder linked below.)



The design is based on the output amplifier in the Tektronix PG508 50MHz pulse generator. We examine this in detail as a Designs-by-the-Masters section in our upcoming book, The Art of Electronics, x-Chapters. I've included this 4-page section in the Dropbox link below. Here's the schematic.



Basically there's an input stage creating a push-pull error current into a folded-cascode VAS stage, and emitter-follower outputs. The secret for fast slewing is to use a high 60mA VAS current with low Ccb capacitance transistors, for a fast slew rate S = i/C = 3000V/us for the PG508. The Tek pulse generator only had to deliver 0.2A to its load, whereas I have to deliver 5A, so I'm using larger, higher-capacitance transistors. Following the principle, F.O.M. = Pd / Ccb, to improve the slew rate, I selected low-capacitance types. They're fragile and I'm using 20, to limit their power dissipation.



My amplifier design is somewhat more complicated, with various features to increase its capabilities, which we can discuss. Here's a dropbox link to my AMP-70A-2 schematic and related files for you to look over. https://www.dropbox.com/sh/dno89om1uezxs8a/AACoJsLyNazSQZvE9_cTcH4Ja?dl=0

Audio-Technical AT-1007 and Technics EPA-2250



I have an EPA 250 A arm a "s" and an AT-Technical Audio-Technical Arm Arm I wanted to know which current MM or MC heads, combine to obtain a better musical result thanks. Giampietro Treviso Italy

I have a set of transformers that I no longer need. Included is one original Eico ST 70 power transformer. Two NEW Eico power transformers built for me by Heyboer. And two 6600 output transformers which are also NEW. I planned to build a pair of KT66 monoblocks and I just don't have the time and too many other projects. I'm asking $500 for the lot.

Most are matched in quads.

Hi everyone,

Aside from the audiophile aspects, what would be the minimum and acceptable level of crosstalk for a phono stage?

I'm asking this because I made a phono stage and the crosstalk level at 1 kHz is about -60 dB. Obviously it's getting degraded moving to 20 Hz.

Any though will be appreciated.
Alan.

Hello.
Need help for microcontroller PIC 16F882 for CAMBRIDGE AUDIO AZUR 650A Amplifier.
Version V1.2.
Anibody Can programm one for me.

Thank you.
Regards

FYI-

https://diy.midwestaudio.club/discussion/2183/iec-test-baffle

Hi guys (and gals),

I have been designing, building and testing speaker systems since the early '70's so I am quite experienced (only for personal pleasure, close friends, family, etc.).

I need a very well designed and great performing 8 inch woofer in the $150 and under range for my next project. I am retired so I think up different designs weekly; sometimes daily!

Box is to be not much larger than 1 ft^3 (28L) and closed design ONLY. This will be a true 3-way; X/O on the low end 200Hz to 400Hz. I'm planning on a 4 to 5 inch fullrange used as a mid from say 200 to well over 4KHz (maybe as high as 6KHz). The tweeter will need to be high output (> 93dB) because of my 60 year old hearing restrictions.

I'm thinking Seas Prestige has the advantage; looking for Fs 20Hz to no more than 27Hz. I have heard HiVi and Aurum Cantus specs. are WAY off! Scan discovery doesn't have any 8 inchers with this low of a Fs.

Comments? Questions? Ideas? Experiences?

This is for a small space only. Vented and TL's are too big for this space. Also, a tuned vented system at say 40Hz will not work since I often listen to pipe organ music. 16Hz on a 40Hz vented will reach X-max at less than 10 Watts. I don't expect deep bass obviously; subs. to come later. If I can get and F3 in the mid. to lower 50's thats good enough!

Thanks!

I have for sale some NICHICON / WIMA capacitors , Japan signal relays , audio transistor & IC /

Payment: PAY PAL
Registered priority ( box + antistatic bags )
Shipping to EUROPE 7,5 USD
Rest of the worlds: 8,50 USD
Prices in USD

If you buy for 70 USD or more shipping is free.

Multiple purchases - ONE shipment

Japan signal relays
Mfg. NEXEN ( formerly NEC )
1) EA2-12NU 12VDC DPDT Stock: 10 1,26 usd each
2) EC2-12NU 12VDC DPDT Stock: 10 1,26 usd each
3) UC2-5NU 5VDC DPDT miniature Stock: 10 1,26 usd each
Mfg. TAKAMISAWA
1) FTRBC012 12VDC DPDT miniature Stock: 10 1,41 usd each
2) RY5-WK 5VDC DPDT Stock: 10 2,14 usd each

I have for sale some NICHICON / WIMA capacitors , Japan signal relays , audio transistor & IC /

Payment: PAY PAL
Registered priority ( box + antistatic bags )
Shipping to EUROPE 7,5 USD
Rest of the worlds: 8,50 USD
Prices in USD

If you buy for 70 USD or more shipping is free.

Multiple purchases - ONE shipment

1) KSC2690A-Y ONSEMI TO126 isolated STOCK: 200 0,35 usd each
3) 2SC3503E SANYO TO126 STOCK 200 0,5 usd each
4) KSA1381E ONSEM TO126 isolated STOCK 400 0,41 usd each
5) KSC1845F ONSEMI TO92 100pcs. STOCK: 400 100pcs. x 0,09 usd = 9 usd
6) KSA992F ONSEMI TO92 100pcs STOCK: 400. 100pcs. x 0,09 usd = 9 usd
7) 2SK772-E SANYO SPA N-FET STOCK 300 0,45 usd each
8) 2SC2910-S / 2SA1208-S SANYO TO126MOD STOCK: 200 + 200 0,52 usd 1 NPN + 1 PNP
9) 2SC3382-S / 2SA1391-S SANYO TO126 STOCK: 400 + 400 0,44 usd 1 NPN + 2 PNP
10) IRS2092S INFINEON SOIC 16 STOCK: 15 2,35 usd each
11) LT3045-1 ANALOG D/ LINEAT MSOP STOCK: 5 7,46 usd each
12) LT3094 ANALOG D/ LINEAR MSOP STOCK: 5 7,63 usd each
!3) LT1166 ANALOG D. LINEAR DIP8 STOCK: 2 6,55 usd each

(Cross-posted to the headphone forum)

I have this portable "hybrid tube" headphone amplifier. The Little Bear B4-X. I adore it, it sounds just to my liking. It runs on battery power, and I generally use it by plugging it into my phone, ipad or laptop. However, it has a flaw. If it is connected to, let's say, my laptop, and then I plug my laptop in to charge, the headphone amplifier produces a fairly loud 60hz hum through the headphones. When I touch the metal chassis of the laptop, or the metal parts of the 3.5mm audio signal cable leading to the amplifier, or the metal body of the magsafe charging cable, the hum immediately vanishes. Therefore, it is only possible to use the amplifier with a source that is ALSO running on battery power.

I'm not knowledgeable enough to know why this might be, or how I could attempt to fix it. Perhaps there is some modification I can make to the device which will solve this problem?

I have tried reinforcing the chassis ground on the amplifier itself, even adding a second lead from the negative leg of the battery straight to the grounding hole on the PCB. Nothing seems to make any difference. I have some experience building audio electronics from kits. I know my way around a soldering iron. So if I knew WHAT to do, I could certainly do it. I found this sub after a search, and thought maybe someone here could help me.

I welcome any input or suggestions. I've attached a picture of the PCB here, in case it helps. Thanks in advance.

I have for sale some NICHICON / WIMA capacitors , Japan signal relays , audio transistor & IC /

Payment: PAY PAL
Registered priority ( box + antistatic bags )
Shipping to EUROPE 7,5 USD
Rest of the worlds: 8,50 USD
Prices in USD

If you buy for 70 USD or more shipping is free.

Multiple purchases - ONE shipment


Nichicon capacitors:
KZ series ( PREMIUM GRADE CAPACITORS )
1) 47uF/50V Stock: 100 pcs. 0,30 usd each
2) 100uF/25V Stock: 100 pcs. 0,32 each
3) 100uF/50V Stock: 100 pcs. 0,47 each
4) 220uF/25V Stock: 100 pcs. 0,519 each
5) 470uF/25V Stock 100 pcs. 0,84 each

FG series ( HIGH GRADE CAPACITORS )
1) 100uF/63V Stock: 100 pcs. 0,72 each

FW series ( STANDARD GRADE CAPACITORS )
1) 2200/35V Stock: 20 pcs. 1,16 each

KA series ( HIGH GRADE 105C CAPACITORS )
1) 47uF/25V Stock: 200 pcs. 0,222 each

PW series ( low impedance )
1) 100uF/63V 8 x 15mm Stock: 50 pcs. 0,32 each

WIMA
MKS2 series
1) 100nF/63V 5% Stock: 200 pcs. 0,24 each
2) 2.2uF/50V 10% Stock: 150 pcs. 0,75 each
FKP2 series
1) 10nF/63V 5% Stock: 150 pcs. 0,297 each

I have a quite a lot of unused drivers that were part of an auction I won way back and my ht is still running first gen sony pascals, so I decided to make new ht mains.

The parts are audax tm025f7 titanium tweeters and tannoy 4" pd9ec woofer probably also made by audax. Woofers are used in mercury surrounds and some mission and magnat speakers..
I have 7 woofers and 4 tweeters so I will have some spares at hand after doing the lcr speakers.

I remember that both had pretty flat fr when I measured them a few years ago.

I took out the trusty dayton dats and measured the woofers.

In simulation they seemed to require quite a big box, but I got semi decent results in 7L br tuned box with two woofers per cabinet.

So I opened up fusion and tried to whip out a design that's visually appealing like the sony pascals are.

These will be 3d printed enclosures so I prioritized printability and I also could go wild with the visual design, since no wood working will be involved.

Another goal was to NOT need ANY post processing of the printed parts so I landed on 2 color print with a fuzzy skin surface.

To evaluate the printability and visual design, I printed out a miniature and a full size test print of the top part. The test prints were mandatory also because this is the first time using petg filament for speaker enclosure.

The results were encouraging and print profiles will only need some further adjustments, so I just went ahead designing all the features in fusion 360.

The tweeters will get a printed waveguide and this is the first time I get my hands messy with akabak software.

The crossover will be designed after I have finnished the enclosures and listened the speakers in active config.

Frd and zma files will then be measured in situ and I'm going to try match the active setup as close as possible with the passive x-over.

Let's hope it all goes well, since this is really backwards method compared how I usually design speakers 😅

Hello everyone. I have a Krell KSP-7B preamplifier, but we lost the external power supply when we moved. I'm willing to do it. Does anyone have a schematic of the power supply and any idea what the supply voltages and currents are?
Thanks in advance.
This foto from internet.

No longer available


$25k news in 2005

Asking $11500

Hi, i am looking for Denon POA 1003 service manual, have been hunting everywhere, no change for now
Thanks

Hello, I have 4x Saligny LCs that are brand new and unused. My applications are centre tapped.

https://evotronix.eu/product/saligny-lc/

£80 inc shipping to UK address.

hello, I'm currently in the process of designing my first speaker and I find myself blocked with the simulation of diffraction. the drivers i want to use have off axis FR magnitude graphs, respectively 0, 30 and 60 degrees .

The problem is that VituixCad's diffraction simulation tool, while it can give me off axis responses for a given baffle, can only take one FR as an input.

What is the best way to go ? Should I only use the manufacturer's on axis FR and the simulated off axis responses or is there a better way of doing it ?

I was thinking something like using the manufacturer's on axis frequency response to simulate diffraction results between 0 and 30 degrees, using the manufacturer's 30 degrees response to simulate 30 to 60 degrees and so on, but I don't know if that's a valid way of doing it.

Thank you for your time

Teo

I have a pair of lightly used B&C DE250-8 compression drivers for sale for $100 with free shipping. Shipping to 48 contiguous states. Payment via PayPal.

Hi folks,
I will have a Super Bassman 300 on my bench within a few weeks. It gives me the time to search for a schematic.
So my question is asked: Anybody with a schematic of this amp?
The problem as far as I've been told is that the auto bias circuit is disabled or even removed. It also need a thorough check-up and a back to factory settings.

Here a picture of the amp.
The Super Bassman CFA7002 is not the one. It has 4 inputs while this amp has only two.
No Deep or Bright switch, only a Vintage/Overdrive.

Thanks for reading and possibly a schematic.
Cheers,

Heat dissipation and accuracy are all the rave with todays highly portable processors but for basic processing like over and under voltage protection say switching on the power to the main trannie if voltage is either between 80-145volts or 180-290volts and auto selecting primary windings configuration if voltage is above 145volts one can use 12volt logic rather than 3.3volts.

Hi, wonder if you could help me please? I am curious- I am thinking of using my basic Sony Walkman in my car straight into line level in of my DSP, and my hifi (Denon DM41) hooked up from the headphone out jack to the line level in. A 3.5mm to 2 x RCA cable. I am nervous to do this for one reason. Back in the 1980s, I had a Realistic Karaoke Machine (Concertmate 2000) bought from Tandy here in UK (or Radio Shack in USA). The power output was poor as was the speaker, so I connected it up to my Kenwood Receiver - this again was from the headphone out to the line level in. However, it repeatedly blew internal fuses in the Karakoke machine. Sounded great, but was constantly in the repair shop. I don't understand what fuses blew, but I can remember turning it on and it just made an awful and loud humming noise through the speaker.
So - am nervous to do this again? Is it risky to connect something via headphone out vs line level out?
But more importantly - what wen't on with that machine to blow fuses? My knowledge of electronics is extremely basic - but am curious to understand what was the mismatch that went on there, as people nowadays connect their ipods, ipads, mobile phones to their hifis with the 3.5mm headphone out.
Your help would be really appreciated.
Thanks
Julian

Used BB PCM 1704-K.

$100 + postage at cost.

R

Hello diyaudio family, the problem of the device is that when the plus and minus are connected, the LED light turns red, there is no reaction when the remote is connected, there is no defective part around the TL494, can you help?

45 tube driven by 6SN7. .1 uF coupling capacitor. Does a 220K grid leak resistor seem reasonable? Should I go higher?

Hi, there is an "automatic" calculator on the internet to calculate the value of components for the RIAA in a prephono scheme like the ear834 (the RIAA ring includes the tube v2 and v3) and like the Marantz 7 or Audioresearch sp3/6/8 (RIAA ring includes all 3 tubes)? Many thanks 🙂

Hello all: I just registered here, so this is my first post.

I have been debating between buying a Buckeye or VTV class D Hypex Amp. Cost is $1100.

I got to thinking wouldn't it be cool to build my own amp. Unsure if its even possible or what the cost would be.
I want to power my front stage LCR (Emotiva C2+ & Revel Concerta2 F36)

My requirements for the system are 500w x3 channels and a RCA/Banana Plug connectors.

I figure I probably would not even save that much money, but it would be a cool experience.

Can anyone point me in the right direction on where to look, and how to get started?

I have 0 experience with electronics like this. Most experience I have is installing speakers and a head unit in my car. My ONLY soldering experience is soldering a loose speaker wire back onto the speaker chassis.

Would building a 3 channel amp with 250wpc or 500wpc be too much of a undertaking for somebody new?

I am debating between Hypex vs Purifi as well.

Any help you all could provide would be greatly appreciated.

(Side note: What is this forums thoughts on the Texas Instrument Power supplies, being used by Fosi and AIYIMA. Such as the Fosi V3 Mono)


________________________________________________________________________
Edit:
After using the search bar it appears that a kit would be easier.

Apparently " Class D amps use SMD chips" which are not for a beginner.

Any help just pointing me in the right direction would be great !!

A very well respected book. Just pay for shipping.

FYI-


Google Translate
https://translate.google.com/

Drivers: Dayton Audio RST28F-4, RS52FN-8, RS270-8
https://linhkienloadai.vn/products/loa-davalon-boi-maybelle-audio

https://linhkienloadai-vn.translate...uto&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp

https://linhkienloadai.vn/collections/mau-thung-1

Crossover @ 10:30-11:00 first video
https://maybelle.com.vn/diy-loa-ava...-su-dung-cu-loa-cua-dayton-audio-nd80938.html

Crossover. Cabinet?

This must be an FAQ, but I did search this forum for related threads and came up empty. Are there off-the-shelf speaker enclosures routed to mount the 8" Neo-8 drivers? Same dimensions as the GRS 8" planar drivers that Parts Express sells now. I've been running mine using temporary enclosures for far too long, and post-COVID I no longer have access to a shop where I could do the routing myself.

My question is somewhat counter to the DIY ethic, but I love these drivers and would like to finally get them properly mounted.

SOLD


I have a pair of like new, maybe 5 minutes on one FaitalPro HF146R compression drivers, with original boxes (will send / add pics later). $400 for the pair shipped to the lower 48. Also have a pair of LTH142 horns as well - +$100

Really unsure of the best place to put this, but really wanted to document it in case it actually works well!

I've been doing a huge amount of work over the last 18 months or so to try and open up the MOST bus audio system that can be found in cars, eventually creating a MOST bus HAT for a Pi. I am now onto an STM32 based board that will act as a sound card for transmitting audio and control messages.

For a long long time I have been tempted by some multi room audio, and ever since I have been play with the MOST stuff I have been thinking how well it could work with that.

For people that don't know a huge amount about the system, here's a quick overview of it (forgive any numbers being wrong, this is all off the dome!)

MOST is a fibre optic network that has a network master. The network master sets the Fs of the network, either 44.1khz or 48khz. It transmits upto 15 quadlets of synchronous data at once, so allows up to 15 16bit 2 channels streams all at once. A device can stream audio onto the network after negotiation with the master, and any device can retrieve that audio off of the network aswell by setting those quadlets to be assigned to it's own sink.

So here's my thinking of how I can have a play with this.

I've managed to source 10metres of the correct plastic fibre optic cable from ali express for £14, I am going to put a MOST device into everywhere that currently has some type of amplifier (man cave, living room, garage, kitchen), I'm then going to route the cable into each room and build some kind of web app to control the system. So if I am playing audio on my Mac, I will stream that onto 4 channels, if I want that audio picked up in the living room, connect that device to those 4 channels etc etc.

Now I know someone will raise the question and yes I know this is a lot of effort for something that can be done wirelessly these days, but I have a bunch of spare devices that work perfectly well from prototyping etc, also I've grown rather attached to the system, and most importantly - it's going to be great fun!

Anyhow, that's the current thinking, I am happy to keep this post updated if people find it of interest!

Greetings to all, I would like you to help me solve this problem, I have this Monster POWER that was working perfectly, I went to adjust the front brightness to stronger because it was very dim and when I increased the intensity, the Monster Power turned off, it starts to the blue CLEAN POWER ON light flashes and after three seconds the red ABNORMAL VOLTAGE light activates, it flashes for about 3 seconds and the CLEAN POWER ON option is activated again, thus remaining in a loop, three seconds in this option, it goes to the other for three seconds, any idea what's happening? Could you help me solve this problem? Thank you for reading.

For those of us guys, in our best age, who likes old school speakers with large high sensitivity paper midwoofer and wide baffle here it is.

We are goong back to the good old Snell days but with more dynamics and especially details in the treble. The alu dome tweeter sounds indeed good. And you can play loud to.

One of the major benefits with 8 inch and wide baffle is warmer lower midrange and very good punch in the bass. It sounds good with all kind of music.

It is also an easy load for the amp.

Some will comment the power response dip in the crossover area in this and all 8 inch + dome tweeter constructions but to be honest, the sum of advantages will make up for this. And you can barely hear it.

The drivers is as «high end» as you are used to in the HiFi shop, but not expensive though.

Complete drawing and crossover description is here:

https://www.seas.no/index.php?optio...s-aphel-kit&catid=66:seas-diy-kits&Itemid=345

@BP1Fanatic , what is this the dudes thing about freqs and Platonic solid shapes and angles and wavelengths?

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Hi,

I've got some monster 845 SE amps based on the Grover Gardner circuit. (Parallel 6N7 to triode EL34 to 845, SS rectified CLCLCRC. This isn't my troublesome two chassis stereo version of the same circuit I've posted about in other threads.)

When I got them, one had a low level 120hz hum. After using them for two years, I took them to the bench to replace an intermittent power switch. I got overly excited and replaced all of the power supply capacitors (many, given the series caps), changed the filament supplies changed to Coleman regs with transformers to match, swapped in newer and fancier switches and jacks, tidied up some wiring, etc.

After deploying the parts cannon and bringing them back to life, one amp is still very quiet and the other STILL has a low level 120 hz hum.

It could just be unlucky layout on the one side. They are huge, but maybe not huge enough. Maybe the big ground buss arrangement that is fine for one isn't loved by the other. I'm not going to explore major layout changes or a complete rebuild. I could turn the PS chokes 180 degrees, but I can't imagine that would be much help.

I'll keep staring at it until at least next weekend and check all the solder joints again. I'll review some threads about hum, but I've read a lot after battling many humming tube amps. Other random thoughts?

Paul

Hello for all,
I have for sale severall boards from Tripath,for the people interested you can check here:
https://www.ebay.de/usr/dialedinmusic?_trksid=p4429486.m3561.l2559

I really like my Technics SL-Q350 turntable other than the higher 60 Hz noise in the right channel. The left channel is great. I want to use it for ripping to digital with the pspacialaudio Stereo Lab software and I'm trying to get an 80 dB SNR in both channels. It uses T4P cartridges that I like, so I am wondering if it is possible to rewire the tone arm at all. The right channel has about 15 dB more hum than the left. I did my best to manage the wires that are easily accessible in the underside of the chassis, twisting the wires for each channel together tightly and keeping them away from other wires had no effect. So the only wire left is in the tone arm and the few inches that go through the gimble. Apparently the wires are far enough apart to create a loop area on just the right channel. The resistance of both channels to the cartridge is the same, around 0.5 ohms. Disassembly looks like hours of work and lots of parts, so I thought I would ask if it's possible to swap wires into that tone arm and T4P head shell?

Hi i have this power amp Quested dx 3000, and looks like is very rare,i am triyng to find schematics cos i have a problem with one channela ,but i cant find anything ,i wropte to quested but at the moment they cant find information,so if somebody have informaton about this amp please let me know

thanks

I bought a pair of Totem Hawk speaker. However, one of the tweeter is blown. And I ordered a new tweeter from my local Totem dealer. I removed the old one and install the new one and found that the original circuit has the polarity reversed. The crossover is a simply first order design. Can anyone tell me why the tweeter polarity is reversed? Also in the tweeter circuit, why do they used three resisters in parallel along with one resister in series? Can them just use one resister? Is it because a specific resistance value that they want to achieve?

thanks a lot in advance

As there was a lot of discussion about microphone distortion here recently and I'm actually working on a pressure chamber which can produce >160dBSpl ... I spent an afternoon to do some microphone measurements.

Setup
A pressure chamber is a device with a speaker membrane with a very small and 100% sealed front chamber. This pushes the resonance frequency of the 8" speaker to about 350Hz in my case - the volume is that small. But you can produce huge pressure changes now!
Measurements as always done with proper gear (APx515, Class1 Calibrator, Benchmark AHB2 Amp etc).
Measurement frequency is 250Hz (to be sure we are in 100% pressure chamber behaviour and it's the recommended calibration frequency by B&K and GRAS), stepped level sweep, 31 steps.

Check of the chamber - how much THD produces the speaker.
Such a pressure chamber produces stupendous SPL at very little membrane movement - so there is very little THD from the speaker. To check my limits I did the first 2 measurements with a GRAS 1/4" 40BD capsule with 2 different "preamps" (actually just impedance converters, they are just called preamps but there is no amplification).
That's the result.

There is a LOT of noise and some strange stuff between 115 and 135dBSpl going on with these 1/4" capsules - legit THD measurements are only starting from 140dBSpl and up. So we produce 150dBSpl with <1%THD and 160dBSpl <3%THD. We don't know if that's the speaker or the refmic! (I have an idea ...)
But we are sure about staying under 1% <150dBSpl and 3% <160dBSpl

So how are our microphones performing.

Here you see the linearity graph. 160dBSpl is easy for our 1/4" capsule. Not so for the other microphones ...
M50 gets to 145dBSpl - spec is 140dBSpl
M215 around 140dBSpl depending on capsule sensitivity -> preamp distortion. Spec is 135dBSpl.
I didn't bother to look after the Behringer Mic spec as it's just here as deterrent example - but >130dBSpl is actually not bad!

But what about THD?!
Here it is - the truth about reference microphone THD:

As expected ... don't use cheap measurement microphones for delicate measurements. They can't do them. The Behringer is out.
Interesting is that the Earthworks has higher THD as the M215! Noise area is up to about 105dBSpl (there is a lot of noise in the pressure chamber cause of it's sensitivity!!!) but then we get valid measurements. At the specified 140dBSpl max it has already 2% THD - that's A LOT! Studio microphones are normally specified with 0,5% THD, somtimes with 1% when the manufacturer wants to push it a little.
M215 - 135dBSpl is where the preamp starts distorting - that's not a limit of the capsule! Actually - it is when you take the 0,5% THD rule ...
BUT - one of the M215 amplifiers produces more noise as it should. Noise should be less as the M50 (dark green) but number 1 has more noise (light green). Will have to investigate, maybe just dirt in the high impedance area (these mics don't get pampered).

You can calculate your THD from this graph for lower SPL. -20dB -> 1/10th of THD. Even the Behringer follows that rule, it's how a condenser capsule SHOULD behave in theory. And they do!

So what about higher order harmonics?
tbc.

Very early on in my electronics heyday, I was replacing some capacitors in an old RTR I had and I replaced the electrolytic motor capacitors with other electrolytic, of same value. After I was done rebuilding it I ran it and a few seconds later I heard a big pop. That is when I learned that you can’t just put regular old electrolytic capacitors in place of ones rated for motor use. is the case the same for polypropylene? I see that many people now use poly propylene for the capacitors, do they need to be rated for that or pretty much any poly propylene work in that position?

I have a 2.5 µF at 250 V AC and a 6.8 µF at 125 V AC. I know that capacitor is ready for 400 V DC are also rated for 250 V AC, so could I just swap something like this in? Or is it absolutely necessary I get one rated for motor use.



Thank you,
Dan

Hello all, here is a shot in the dark. Please excuse if a stupid question. This is related to my Cub Sandwich sub build

Let's say I wanted to keep the speaker passive and use if with an outboard amp. It's a very small cab in a system sealed by passive radiators. I have designed in a heatpipe to take hot air away from the motor vent. Is there a way to bleed off a lil bit of power from the speaker terminals to power a small fan to encourage air movement in the pipe?

I.e. an active fan inside a passive speaker without any other power supply for the fan

Thanks and regards
Randy

What is the best internal lining for sealed and ducted boxes?
Do sealed boxes really need internal lining?
I once made a sealed box and covered it with glass wool but I was never able to check whether or not it made a difference to the sound.
For ducted boxes with subwoofers intended for deep bass, what coating should I use?

I'm working on creating a "Wall Sequencer" that let users create their own beats.
I'm trying to get a budget friendly options to build the right Audio Setup.



I'm looking at the following:

• Professional Audio Amplifier Module 2.1CH TPA3255 Chipset Imported JRC2068 For Home Sound Systems For Subwoofer Speaker
• ZK-3002 TPA3255 Pure Rear Level Digital Amplifier Board Stereo 300W x 2, Bridged Mono 600W AMP Audio Music Power Amplifier Board
• YS-AS21 2*220W+350W 2.1 Channel BT Digital Power Amplifier Board TPA3255 AMP Subwoofer Treble Bass Tone Audio APP USB Function
• SAMP-200 Dual core TPA3255 High power 2 channel amplifier board 600W+600W
• UNISIAN TDA7498E Bluetooth 5.0 Amplifier Digital High Power 2*160W+220W 2.1 Channel Audio Power Amplifiers Board DC32V
• XH-A128 TDA7498E Digital Power Amplifier Board D12-32V 160Wx2 And 220W Stereo 2.1 Channel Amp Amplifier Board
• TDA7498E Built-in cooling Fan ZK-HT21 AUX Bluetooth-compatible 5.0 USB Stereo Audio Power Amplifier Board 2.1 Channel
• 220W+220W+350W High Power 2.1 Channel TPA3255 AUX USB Bluetooth Audio Power Amplifier Board Frequency Treble Bass Volume Control
• ZK-AS21 2.1 Channel TPA3255 Bluetooth Digital Power Amplifier Board Module High And Low Tone Subwoofer 220WX2+350W
• 2*220W+350W TPA3251 Bluetooth Power Amplifier Board 2.1 Ch Class D USB Sound Card Subwoofer Theater Audio Stereo Equalizer Amp

The wall will be outside in the open desert.
My goal is to have a clear sound of mostly Electronic (Techno) Instruments, so clear sound and low frequencies are important for me less than volume (power).
I believe the setup should be 2.1 speakers.

Would love to hear your thoughts an ideas on how to get the right Class D for me.

Hi folks,
Is this an issue with the LCD itself or the circuit? I am thinking of replacing electrolytic capacitors anyway as a preventative maintenance.

Another issue I’m seeing is brightness level will not adjust (stuck on High) in the AM band.

I’ve attached schematics to the T40, similar model. The LCD model on the T40 appears to be NEC FIP7A8S, so far no luck with finding this model on google.

Thanks.

Photos of LCD brightness set to Off and Low, and T50 boards.

Foobar2000 released the VST 2.x/3.x Adapter plugin on 2022-11-17, the latest version is 0.12, the plugin allows VST effects to be used as a DSP in foobar2000, VST/VST3 can be used. In this way, the foobar2000 can directly call to load the FIR filter as a DSP digital crossover. It's extremely simple and plays smoothly.
Hardware:
One PC. One multi-channel DAC.
Software:
System software version: Windows7 SP1 or later. Install the sound card driver.
Foobar2000 version V1.6 or later, preferably V2.1.5.
VST 2.x/3.x Adapter Current version: 0.12。
convolver4-4vc++。 convolver4-4vc++ is an open-source, high-performance Windows application for applying a finite impulse response (FIR) filter.
rePhase。 Speaker phase linearization, equalizer, and FIR filter generation tools.

First, install convolver4-4vc++ on your system. Then, the administrator runs rePhase to generate the FIR filter file (low-pass .wav, bandpass .wav, high-pass .wav), and uses a text editor to generate the txt text file of config.
Install foobar2000V2.1.5 on the system, download and install the VST 2.x/3.x plug-in, add the VST 2.x/3.x plug-in in the DSP management of the preferences, configure the VST 2.x/3.x plug-in, add the folder where the installed convolver is located, select convolverVST (VST v2 32bit), and display the VST Effect in the pop-up format Click Filter/config in the configuration window, select the config file generated earlier, OK. Select the default speaker exclusive in the output and play it.

Purchased a decent Audio Technica turntable with the stock cartridge and want to replace the original cartridge with one I have owned for many years. I am concerned with the additional weight of the Pickering XV-15 cartridge with the D1200 stylus and brush that I want to use. The weight of the Audio Technica cartridge with headshell and hardware is 15.525 grams. The weight of the Pickering with head shell, brush and hardware is 17.8 grams. The stock Audio Technica head shell and hardware is 10.7 grams.

The only information I was able to come up with is the Audio Technica can use a cartridge between 3.5 grams and 8.5 grams. I can find no information as to compliance or tone arm weight.

Haven't used it yet as I'm still trying to find more information so any help or comments would be appreciated.

Hi there,

Am coming from France, south France, Montpellier.

I am a collector of audio devices but mainly of CD players.

I chose this forum because it seems to me to be the most in-depth in its discussions.

Thank you for welcoming me.

Hi there,

I need your suggestions please. It's a curious failure, at least for me.



Most of the time, we insert a disc (in perfect condition) and it fits correctly in its slot.
The disk does not turn, we hear the actuator click while it makes several movements, then nothing and the display indicates zeros.

We eject the trapdoor and its disk several times AND! the disc starts to spin, the Toc is read immediately.
We insist on the "read" button, the actuator clicks once, the disc does not turn.

We take the disc out several times, but this time we press the “play” button directly.
At some point, reading will start !
The entire disc can be played perfectly, without skipping. You can skip back and forth between tracks, change tracks at will !

As soon as you stop the disk, it will not restart. We eject the disc several times and wait for the next reading ! 👽

Notes :

• The central motor has been checked with an external power supply and is working well. I added a drop of oil to the axle.
• I looked at the cable connections to the motherboard, but no false contact
• Using the multimeter on the central motor connector of the motherboard, I have between 4 and 2 volts when the disk is spinning. No voltage when the disk is not spinning.
• Belts have been checked, no problem.
• I also noticed that the LA6520 (ic202) is hot when the second one is cold (there are two on this card)
• The control panel is not the cause, we see the actuator move with each selection.
• There is nothing visually suspicious about the electronic components.

- The soldering under the card was bad originally. it is poor in tin and under the soldering iron, the component legs refuse to solder.
We see in this photo the difficulty :

I reworked a majority of solders correctly and even on the chips

Click to expand...

A view of the entire board :



- I also looked under the optical unit. Maybe a problem with the cms capacitors?
I didn't see anything special on the weld side.



- I then saw that the rubber suspensions of the chassis were all dead !



- I temporarily replaced these suspensions with plumbing washers on hand I had. No improvement.
In any case, even if the chassis is poorly suspended or crooked, the spindle remains aligned on its common chassis facing the optics.
isn't it ?
(and the CD did not rub when turning)

It's only with the revision of the soldering of the board that I find the best. The disc is read once in five, instead of once in 15.

Click to expand...

Click to expand...

I find it hard to question the optics since when the reader works, it works perfectly.
It's a PEA1335, unobtainable or overpriced !

What can I do now ? Can you help me please ?

Doc here : https://elektrotanya.com/pioneer_pd-106_sm.pdf/download.html

Hi Diyers,

I have a MiniDSP 8-channel processor, a Denon AVR-3083 (with pre-in for each channel) and a pair of KEF Q7s. I'm getting set up for bi-amping and bass management trough the MiniDSP. The Q7 is bi-ampable - splitting the woofer from the coaxial mid-hi arrangement. The Q7 nominal impedance is 8 ohm. I've just measured each driver separately (Q7 disassembled for refinishing) and they each measure 3 ohms woofer, mid & hi.
The AVR-3803's recommended minimum impedance per channel is 6 ohm.

Am I going to destroy my cheap old AVR if I biamp with it?

I'm surprised the binding post bridges seem to be series linking the drivers to get 8ohm. I would have thought positive to positive and negative to negative binding post bridges are a parallel connection. (drivers at 16ohm each...) Maybe KEF internally flipped the connections so we are getting 4 +6 ohm = about 8 ohm.

Thoughts?
Thanks

I have one for sale, unused and supplied with interconnects. (I bought three and used two to grreat effect)
Also on ebay:

https://www.ebay.co.uk/itm/285433001874

SPDIF to I2S adaptor also listed.

Hello DIYers,

I'd like to make a shielded cable to connect a tonearm (low output MC cartridge) to an MC phono stage. The phono input is unbalanced (sigh).
A few cables I've looked at are the Mogami W2534 and the W2893, both shielded quad. Another option is Canare L-4E6S sheilded star quad.

If there is a better choice of wire and preferred shield termination style for this application, just lemme know!

I have two of these guys, I cant seem to find info on if these can be safely paralleled to double current and if so whats best practice in doing so?

So I had these on my desktop, and they are deceased after 2 decades of loyal service. Also a tad large, but I liked them a whole lot.

So after a lot of searching and reading (sitting close and phase, open baffle and wall, imaging, that tweeter has ehm questionable reviews apparently), I think the best and easiest option is a nice fullrange in closed box, either a Fane or a Sica, this is (probably?) as large as I can get away with next to my screen. But I'd like to avoid an absolutely huge box.

What is the smallest housing for either of these that I can get away with, is 45-47 liter good? Is it stupid to even ask and am I then better off with 10 inch drivers? About 50% music, 50% games if relevant. I just want to get rid of these crappy Logitechs. Recommend other drivers if a lot better for a small box but try and cap it at say 2×-3× the price.

Hello, I currently has an idea to dampen standing waves in a room, but I didn't find much content about it, to know if this idea would work.

So, the idea is to make a transmission line with one extremity open and the other closed, where the open extremity is the entrance of the sound from the room, so it can pass through the path that will probably have a conicity that decreases towards the closed extremity.
So, this idea came to me when I was thinking about a way to dampen or absorb low-frequency standing waves in a room.
The first alternative that came to me were bass traps, but research showed me that for bass traps to work with good efficiency from 50 to 100 or 200 hz, they would have to be very thick, in addition to the expense of large amounts of rock wool or glass wool would start to get tall.
The second alternative that came to me were the Helmholtz absorbers, but this type of absorber would not be ideal for me, as it only works with a very small range, which would make me have to make several resonators each tuned to an ideal frequency, and they also seem to me to be more complex than the quarter wave absorbers.

So, if this idea can work to dampen or absorb the stationary waves that are in the corners of my room or in other regions of my room, then could you show me content about this type of absorption or if it has ever been tried?
If this absorber idea can work, I'll talk more about my room.

Hello,
Anyone have experience with these thermal pads? I need buy a 32 pcs.

https://www.tme.com/us/en-us/details/cd-02-05-264/heatsinks-equipment/wakefield-thermal/

Greetings all. I just joined this group. My background is researching designing toroidal transformers and have extensive knowledge of same. From what I have read so far, there seems to be some misinformation. Pls post any toroid questions and I will do my best to answer them.

Are there any DIY analog to digital projects, boards or kits out there? I would love to get something like the Mytek Brooklyn ADC (Not DAC) but it's discontinued. That leaves me with searching for a used one or seeing if there is a project for one.

I am having trouble identifying a diode that was physically burned by a cooked power supply mosfet. I could not get clear photo of the diodes in the power supply section but it looks exactly like D3 in the photo, no numbers just black on one end and a thin gold stripe. It has .6 voltage drop one way and reads open when I reverse the leads. I was thinking it’s a 4148. Any thoughts?

Just bought one of these! Yes, it's stereo, not mono. $6! Free shipping!

Why not? 😎😎😎

Promotion TDA7297 Whi Fi Noiseless 2 0 Audio Power Amplifier Board Max 30W 30W | eBay

See attached schematic.

Audio Research terminates the feedback loop connections at the binding posts. Is there any reason they chose that vs. terminating at the transformer? The area behind the posts is cramped, and terminating the wires at the transformer also reduces overall wire length. I don't want to second guess ARC, I'm sure they have their reasons, but it seems electrically equivalent. Am I missing something?

I'm new(ish) to using digital streaming. I had been successfully using Ropieee through a Raspberry Pi over the last 3 years or so. I used various DAC hats or USB outputs to various DACs.

I've now expanded my horizons, and I'm trying out some new things that I desperately do not wish to screw up.

After assembling some of the Ian Canada parts into a very basic setup, I have the Gentoo Player on the Raspberry Pi configured for USB output to a DAC. I set it up as a Roon Bridge, and it seems to be working quite well.

Now, I want to try out the other "fancy" Ian Canada parts to output the signal to the DAC properly over the various interface options.

A few (okay a lot of) questions:

First the I2S

• I assume in Gentoo player one would select the "DAC" as Generic I2S, correct?
• Then, as but one example, I have a few DACs. One is a Topping D90. I noticed that the pinout for the Ian Canada board is:

In the manual for the Topping, it shows the following for phase:



It would seem that I would need to reverse the phase with the D90 (or just remember to do it in Roon, I think) - no big deal.

What's odd (to me) is that it shows the following for DSD:


If I'm interpreting this correctly (highly suspect) the two (Ian's board and the D90 with DSD) cannot match. I can either have the phase reversed or the channels reversed, correct? I don't play a lot of DSD, but I'd like to have it set up properly.

It seems like it may be easiest to change the DSD to DSDR Data to get the channels correct. I can leave the phase alone. It would be inverted for both types. Then, I can just leave the phase inverted in Roon, if I actually care at all about absolute phase... which... I don't really, but...

OR

Are those settings independent of each other? i.e. if I swap the phase in the preceding step, it ALSO applies to the DSD?

I can test all of this, but it would be nice to not need to fool with testing phase.

So, if anyone knows, I'd be grateful.

-------------------------------------------

Next the AES

Onto the one that I really don't have a clue about... Gentoo Player with the TransportPiAES.

Do I still leave the "DAC" in Gentoo Player as generic I2S when I swap over to that?

Also, does anyone know how to use the Ian Canada I2S and the AES boards in a stacked configuration? I'd love to have both options permanently mounted, so I don't have to swap back and forth. However, the Masterclock from the Fifopi can only go to one thing, I think. Any advice is appreciated.

Just getting the Gentoo Player set up and running was a monumental task. In hindsight, it's easy as Pi It just had a steep learning curve for me. It's playing now, and it hasn't glitched, so... I'm leaving it alone... until I may need to change it for the AES board...



Edited to insert thumbnails vs. have the massive pics.

Hi all!

I recently acquired a project preamp without documentation which uses six pentodes dual triodes (two in phono stage plus four in linestage).

I assumed all would be the same E88CC, and prior to turning it on, proceded to test the tubes on my TV-7U/D. Four are Telefunken, one Siemens, and one sans-branding (likely Chinese).

When I began testing, two showed no conductivity for both triode sides, which led me to question whether they were in fact E88CCs. Of course they lack markings other than the Telefunken diamond and country of manufacture.

What's odd is that the two mystery tubes were not in the phono stage, but instead within the linestage section, which relies on matched pairs for the two channels.

Attached is a comparison of the tube in question as well as a known, labeled Telefunken E88CC. The known E88CC has a getter plate supporting the halo post, whereas the tube in question does not. I'm not familiar enough with 9-pin tubes - much less Telefunken models to identify whether this is just another variant or a different tube altogether, so pitching this out to the experts 😉.

In the attahed images, the known E88CC is the one with gold pins and the mirror image of the number "11" inside its diamond on the underside.

Thanks!

Preface

• This report is a follow-up to, "Acoustat Magne-Kinetic Interface MK-121-2 - A Successful Restoration" https://www.diyaudio.com/community/...ace-mk-121-2-a-successful-restoration.404764/
• As stated in this restoration report, "Initial Symptoms. When powered up, annoying hum noise coming from both interfaces." This noise issue was addressed in section "Minimization of 50 Hz induced hum noise" accompanied by Figures 19 and 20 in the report, whereby applying synthetic rubber sheeting to the chassis was effective in reducing the hum noise.
• However, I was intrigued by the comment from Mr. AAM from his review of my report where he kindly replied with, "And speaking of the bias transformer, later units had the transformer mounted on rubber grommets, alleviating the "chassis hum" you experienced."
• As these are my only pair of Acoustat electrostatic loudspeakers having purchased them new in 1980, I would never have known about this subsequent change to the transformer mounting. So, thanks to Mr. AAM for sharing this information, it got me thinking!

Purpose

• While the initial restoration report addressed reducing the hum noise, the purpose of this report is to minimize the noise vibrations at its source.
• Without having information about how the transformer mounting was changed in subsequent production or the parts involved, another purpose of this report is to share with our members an inexpensive solution using commercially available parts.

Anti-vibration method
* Initially I experimented with grommets to modify the bias transformer mounting, but the most effective result came from using rubber anti-vibration studs to isolate the vibrations (Fig. 1).

Figure 1. Elesa VD1-1510M4 (left) not used, and Elesa VD1-1515M4 (right) used in this installation.

• Two vibration dampers are required for each bias transformer, or total 4 for the pair of speakers.
• Of the two series of vibration dampers purchased, VD1-1510M4 of rubber height 10mm and VD1-1515M4 of rubber height 15mm, I decided to first try the VD1-1515M4 as it had the softer spring constant (Table 1). In the event of insufficient clearance between the bias transformer housing and the high-voltage board with the VD1-1515M4, then I would change to the lower profile VD1-1510M4.
• An M4 thread type was chosen as the M4 diameter was close to the diameter of the original mounting hardware, whereas the next size up M6 would require enlarging the chassis holes.

Table 1. Specifications of Elesa Type VD1 Rubber Vibration Dampers - dimensions in mm.

* A full set of specifications for the VD1 series can be obtained from the attached specification sheet. An optional stainless-steel version VD1-SUS is available for wet or corrosive applications but isn't needed here.

Preparation

• Safety. Ensure the AC power cord is disconnected, and the high voltage circuit has been fully discharged.
• A consequence of the rubber damping material is it isolates the earth connection between transformer housing and chassis. Proper grounding is very important, both for safety and to complete the connection to the bias high voltage.
• To re-establish the ground connection a small wiring harness was constructed (Fig. 2).

Figure 2. Pre-assembly showing wiring harness for connecting both ends of each VD1-1515M4.


Figure 3. Partial assembly, VD1-1515M4 pair and wiring harness attached to transformer base.

• The inside surface of the interface's chassis was lightly sanded around the mounting holes to ensure a bare metal contact with the grounding wire lugs.
• Finally, the bias transformer with wiring harness and anti-vibration studs was installed back in the interface using M4 fastening hardware (Fig. 4).

Figure 4. Bias transformer reinstalled with new VD1-1515M4 pair and ground wiring.
* Fortunately, this installation using the VD1-1515M4 pair allowed just enough clearance between the bias transformer housing and the large 50 K ohm resistor (Fig. 4).

Results

• After installing these parts and upon powering up I was pleasantly relieved all transformer hum noise is gone, both interfaces are now dead quiet. Considering the parts cost less than $5 per interface this was a worthwhile modification.
• Previously when placing your hand on the interface chassis you could feel the vibrations, but this is greatly diminished now.
• Regarding the initial approach of attaching synthetic rubber isolation sheets to the chassis, this was left in place as it does no harm.
• Side note, while the reduction in hum noise was clearly apparent, I was not expecting any changes in the audio sound quality. But there is a very subtle improvement with a clearer, more open sound. I don't think I'm imagining things as I have owned these speakers for 44 years and am accustomed to their amazing sound quality, on the other hand I cannot quantify in measurements what I have heard. While it's difficult to say, one theory might be the previous mechanical vibrations throughout the chassis impacted the performance of different components, whereas these chassis vibrations are now considerably diminished.

Final notes

• Why it took me so long to act on Mr. AAM's comment regarding transformer isolation? To be honest the biggest priority after restoring the interfaces was repairing the multiple broken stator wire joints, documented in "Acoustat Stator Wire Repair: Hints and Lessons Learned" and this effort took over a year to complete before I could address the transformer hum. https://www.diyaudio.com/community/...wire-repair-hints-and-lessons-learned.404881/
• As mentioned, I purchased two series of vibration dampers, VD1-1510M4 of rubber height 10mm which I kept as spare, and VD1-1515M4 of rubber height 15mm which I installed and documented in this report. Should one day the VD1-1515M4 rubber become soft and the bias transformer begins to sag, my plan is to change to the lower profile VD1-1510M4 having a higher spring constant (Table 1).
• While not documented in this report, other makes of similar anti-vibration hardware could give similar results.

References

• VD1 series, Japanese. https://www.imao.co.jp/files/ja/pdf/vd1.pdf
• VD1 series, English. https://www.imao.com/files/en/pdf/vd1-e.pdf

Working very well. Good quality parts.

£100 Ono

Fellow DIYers! I am reaching out to you regarding a unique collection of 814 valves that I currently possess. These valves were acquired from France some time ago, and I have meticulously preserved them since then.

However, as life often leads us down unexpected paths, my circumstances have shifted, prompting me to reassess my priorities. Consequently, I find myself in the position of needing to part with these valves.

I am posting here to inquire whether you might be interested in acquiring this collection. The valves are in impeccable condition, having been carefully maintained, and I believe they could be of value to someone with a passion for such items.

Given my impending relocation to another country, I am eager to find a new home for these valves. If you are interested or require any further information, please do not hesitate to reach out to me.

You can read more about this tube here: https://www.bartola.co.uk/valves/2013/11/23/814-se-a2-amplifier/

Thank you for considering this opportunity.

I have 3x KEF Blade Coax drive units that I want to use in a new setup in a new house, together with 8x Dayton RS180 per side in a baffle wall.
(I have 3 of these nice coaxes, so there will also be a center speaker with the same setup but with only 4 RS180 mid)

Does anyone here know how to calculate spacing and possibly distance from floor and ceiling, and possibly have general thoughts about solutions?

Appreciate feedback and discussions!

My thoughts are in this way to solve a lot of the room nodes in the elevation plan. Split frequency will be considered, but around 4-500hz possibly with some overlap.
Originally Kef Blade is shared at 320hz, but I personally feel it is a bit low. There will be a subwoofer to take the bass area.
I have a Minidsp OpenDRC-DA8 for active crossover incl FIR.

See picture for alternative placements of mids.
In one set-up, the coax is at a height of approx. 1.25m, which I feel is somewhat high compared to the approx. 1m sitting position?

For Eminence's Delta 10A - say either a mini-La Scala ~ 15" cube or a "C" horn. If you've something in this ballpark I'd like to see the plan. Simpler is better.

just like to have a fun toy - one of Dr. Edgar's first Speaker Builder Magazine's articles concerned a folded midhorn.

Hi All,

As I was tidying up my workshop, I naturally came across an old Music Angel XD-800MkII for EL34's that I'd bought as a DIY project, without tubes, but with case and transformers. GU50 was (is!) the tube I wanted to use.

So I'd merrily started this about a decade ago, but then got distracted onto something else, and never managed to get back to it. As such, it needs tidying up, I.e populating with tubes, and a circuit, etc.

So the original Music Angle (KT88) schematic floats about, and there's the Dynaco ST70 design which is nice, but that's all been done before, and my original concept was to build a local feedback PP, due to the wonderful sound from my local feedback SE.

Anyway, if I just built old stuff, where would I be? Surrounded by nice, working things? The horror..

So anyway after a few false starts and dead ends (LTPs, I'm looking at you!), this is what I came up with. LtSpice only so far.
The 'slightly unconventional' anode resistors for the 6AU6's (which I'm pretty sure I have in stock, from an old raid on a Tek 545b) to B+ is to give it a 'more CCS like' anode load, without having to add Yet More Bits'.

Caveats: I'm not 100% sure of the B+ voltage. Or the output transformers. Or really, the tube models.. but I've attached them.
The tubelibrary I downloaded from the tube Spice model thread, but I re-wired the GU50 model to match the tetrode symbol. I'm not sure why they don't use the pentode symbol, perhaps some SPICE vs LTSPICE thing.

So I don't get much feedback in there, 6dB or so, but I'm low on gain. But at least this concertina + Schade resists the temptation to turn into an oscillator, so that's encouraging. I could add an input stage, of course, but that's another stage, more distortion and more bits. No feedback beyond the primary, as that would be madness 😆

I did try the GU50 in triode mode too, but that was hopeless. In Pentode mode literally everything is better 😍. This design has a wonderful soft clipping too, tubes seem far more 'elastic' than MOSFETs !

Tubes are chosen as to what I already have, a sure fire method I use to ensure I can build stuff...

Please point out any easy fixes, improvements, etc, as in my ideal dream world, I'll build it and it'll be magnificent.
At some point I'll send a small AC signal into the transformers and work out what the ratios might be too. 🔬

Biasing is a bit glossed over, it's awful in the original, but if anyone has a good circuit for PP tube balance (Pot 1) and level (Pot 2) please can you post it? A handy method to casually null the PP magetic field would be cool, with absolute level setting being demoted to a 'baseplate off' think as that drifting doesn't worry me.

All comments welcome, many thanks in advance!

Selling this pair of IRD MB-100 amps. 100 watts Class AB into 8 ohm and 200 into 4 ohm.

I replaced the chip on one of the amps.

Asking $350 and I’ll ship anywhere in the CONUS for free.

I've seen the late Tim's 859. And he uses a cathode follower. I'm not sure he would do it the same if he were to design it today. Though if a pcb was available I would have used that design. But it will become a rats nest if I build it point to point. But I digress.

How would you do it today? Perhaps a "power drive"?

Power Drive | Tubelab

I have few STU9HN65M2....

My output transformer is going to be a One Electron UBT-1.

I powered down and unplugged my working REL Studio II for a planned power outage to repair a utility pole. Two hours later, when I turned the sub back on, the drivers relay began to click on/off. No sound could be heard except for a brief moment when the relay tried to connect the speaker drivers to the audio circuits. Needless to say, my sub is no longer working.

Visual inspection of the board show the caps to be in like new condition (no bulging or leaks anywhere). In fact the whole board looks brand new.

This sub was always left on and only turned off either due to infrequent power outages (storms) or when away for an extended time. Otherwise, the powered sub is always on.

Has anyone experienced this where only the relay is faulty or is it the power supply causing the clicking? I haven't tested any voltages yet needing advice on what/where to test. See image below for the relay picture. I can't find a schematic for this unit.

I did measure the relay's coil voltage and it fluctuates with each click - rising to a few volts then falling to zero. My digital meter is not fast enough to catch it because the click is so fast.

Thanks