An observation . . .

I have not been involved in PA systems for at least 20 years. The thinking back then was to take the bass out of the monitors. The bass player has a Marshall 4 x15 2 feet away so fold-back was focussed on the upper frequency ranges - vocalists need to hear what they are singing.

So, I'm watching a Trevor Noah video on Youtube and I'm wondering why he has at least six subs on fold-back?

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Smith & Larson woofer tester #2 still open?

Good afternoon everyone happy New Years. I happen to be a long time supporter and fan of the woofer tester # 2 buying 3 of them in the past and selling them cheaper to a few Acquaintances of mine to help them out. So I noticed that they never updated past windows 8? Now it’s windows 11. The reason am posting this is am looking at my options of getting a new computer and was wondering if anyone has direct contact with them? I have e mailed them a few times no answers back? I know they have some awesome programs out. I’m just bummed because I want to step up but, am afraid it will be a paper weight in a year or so? My windows 8 computer is very slow and takes to long to update every time Ugh. So if you know anything please let me know? Thanks for everyone’s help. Jeff

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Need DIY chassis to finish Remote Volume Control project

I'm trying to complete installing the innards for a DIY Remote Volume+Input Control I bought on eBay by putting them in an enclosure which has a front panel that is cut out to fit the LCD display and a back panel that has cut outs for the four RCA-jacks.

These are the specs I've been given that will fit but I'll settle for the enclosure and I can do the rest. Prefer a non-metal enclosure.

External dimensions: 273x190x64mm
Internal dimensions: 262x175x55mm
Accessories: Four machine feet, all aluminum knobs, power input sockets, screws

Can anyone recommend a supplier/vender/source?

Attaching three pix: two of the enclosure kit, one of the innards.

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Tandberg TCD 310 Dolby not working on one channel.

Hey all! I have a Tandberg TCD 310 that I've been renovating gradually. Upon what I thought was completion, I noticed that Dolby only works on one channel. When I switch position of the boards the problem follows with it, so there's where the fault lies. All the electrolytic capacitors and some tantalums (in the signal path) has been recap'd. I've also replaced all transistors on the faulty board without any luck. Anyone has an idea where to look next?

Skärmavbild 2022-01-14 kl. 13.45.06.png

NTC Thermistor As Soft Start For Tubes

Hi!
I would like to use NTC as soft start for my SS Tube PSU.
I have some questions:
Does anybody have experience with NTC in tube PSU circuit?
What is the best way to use a NTC Thermistor for Soft start?
1. NTC connected before the power transformer. On the primary side.
2. NTC connected after the power transformer. On the secondary side, which goes to the B+ supply.
Some people says soft start is needed only for B+,
another says for heather too,
or even for both (B+ and heather),
or even its not absolutely needed...
For me the most logical would be soft start for both supply, so the NTC should be in the input AC line.
Should I use in this case CL-60 or CL-150 NTC?
The transformer is 200VA and the AC line is 230Vac.
Greets:
Tyimo

Replacement High Temperature/Long Life or Horizontal Deflection Capacitors

In a search for particularly long-life capacitors someone suggested that I look at capacitors that have a proven track record in horizontal deflection circuits. They said that horizontal deflections circuits are very tough on capacitors.

Can anyone suggest a brand and series which have a solidly proven long-life in horizontal deflection circuits?



The actual application is in the SMPS of a Tektronix oscilloscope (they call it an inverter). I was looking at UCC KY, Nichicon UPW and Panasonic FM-A series. All are 105C and low ESR. (I was looking at 10mm to 12.5mm diameter for 1000uF and 50V or 63V to get lifetime ratings of 4,000 (FM) to 10,000 hours (KY).) The originals are Mallory of which a number have leaked.

I would like to pick a very reliable capacitor that will never need to be changed again. (Outlive the rest of the instrument.)

HQ-Flagship DAC MKII

Here are some pictures of my DAC, please take a look at it, many thanks!

Quanghao

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Scheduled for resolution Using the named day of the week in the date of a post is confusing to people who don't know what day it is which is probably half of us

No year, month, day. it shows for example: Sunday at 10:30 AM. I hope this is not the way it will be. Note: If one hovers mouse over the date it shows the whole date as we usually look at. Also if using the Enhanced print feature the date does not show up. Real problems if trying to save in a chronological order. Only started happening in the last week.

MTM or TMT Center Channel Speaker

I acquired an Angstrom Center Channel speaker model: Modular Six/C. Instead of what's normally configured as an MTM with tweeter in middle for a center channel, it has one 5" Vifa glass fiber mid/woofer (SG14SG01-8 ohm) with two Vifa soft dome tweeters (TC20SD05-06) on either side in a vented enclosure. It sounds good but was seeking some comments on this TMT layout compared to MTM. Granted an MTM speaker lying down is not the same as an MTM standing up (a.k.a. D'Appolito) and the polar sound distribution (hence lobbing effects) are not ideal in a horizontal position compared to vertical. I understand what the best layout for a center channel is W-M/T-W and that is woofer on the sides of a tweeter above a midrange in the middle. Anyone see the benefits of this TMT config. and if its better or worse than an MTM type as far a phase/lobbing and ultimate speech articulation, etc.? I struggle to see anyone using this layout in a center channel speaker or otherwise...
Angstrom Modular Six-C.jpg

FS: Aksa Alpha 20 class A mono blocks.

This is a dual mono amp running in Class A at around 37 watts using
This is the Aksa Lender P-mos Hybrid Aleph boards
. It uses a pair of the SLB power supply boards
A fantastic sounding very clean Class A.
That includes the 2 Aksa Alpha amp boards the 2 SLB supply boards
And the 2 Antek Transformers and the Heatsinks
Asking $680.

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GOLDRING 10-20, a Stylus replacement for cheaper

Hi again folks,
I´m coming from marvelous threat open by dimkasta: https://www.diyaudio.com/community/...io-mm-for-30-euros.234544/page-2#post-6881127
Encouraged enough now, I´ve decided to repair my GOLDRING 10-20 and it broken stylus in the... 90´s!!!!
the replacement stylus costs about 175-200 euros, if not more, an amount I am not willing to pay, and now I feel able to look for a cheaper replacement needle. I wonder if it will be the same with Goldring, and their stylus are made by another manufacturer (Chinese for sure) and they only care about choosing the model? The ways they make profit know no bounds.All I need is to find the same type or similar.

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For Sale Pearl phono stage (original one)

After 20 years of being almost complete but in storage, it's time to go.

Pearl phono stage (first one). As you can see, the boards are almost complete. I had some additional components in the same container as the boards and transformer. I can't guarantee thats all you'll need.

The transformer is a Plitron, from what I recall it was very expensive.

$300 obo plus shipping, US only please.

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D-150A-II Hot resistors in Ch1

Sorry if this has come up before I've been searching and haven't found much. I have collected a few Crown Series II D-150a amps (all above SN 61000) and it seems channel 1 is usually where a failure has occurred. I don't know the history of the units and I hope to repair them if practicable. I've got one amp that sounds pretty good I use as a reference but on it I find R3/R8/R!0 get notably hot even on light duty. The PCB has heat marks on it as do the other units. How normal is this? I've recessed the resistors from the board increasing wattage, checked output bias/diodes, updated capacitors,, and have the D-150A II service manual to assist. Should these get that hot. Any other tips out there what to check?

thanks '

Amplifier is an extension of its power supply

In preparations for my future amplifier builds I decided to start from a good power supply. For maximum performance, dual mono configuration is a must. But, I felt that this is a waste of my financial resources and planet Earth resources. Two oversized audio grade transformers, huge capacitor banks, specific “sounding good” capacitors, etc. Single regulated linear PS would be better than ordinary dual mono CRC, but I didn’t find any with low dropout, high PSRR, high output current, low noise, low output impedance and good transient response, in the same package.

So, I decided to make a one.
Silly me.
It was not an easy task.

Best approach seemed to be an add-on module for various existing CRC power supplies that replaces resistor in the CRC line and turns power supply in to the regulated one. I had some excellent CRC PS boards with active (synchronized) rectification from prasi (ANALOG DESIGN) and that was a starting point.
Final result is on the picture below and those modules should fit to all CRC PS designs suitable for amplifiers available in the Pass Labs section.

attachment.php


They work, as is without any changes, from 10 to 65 V output voltage and load up to 10 A, with dropout voltage of 0.15 V for 10 A load, PSRR greater than 100 dB @ 100/120 Hz and total noise less than 3 µV.

Diyaudio is a place where wealth of designs is available for free and, by extraordinary generosity of Mr. Nelson Pass, we get for free IP that someone else would charge you an arm and a leg.
Completing design that was not available and that could be of use to someone else except me, the only right thing to do would be to make an additional effort and provide complete documentation, but … not a small baggage comes along with such decision. After some debate with myself, here we go with my small contribution:

An arguably better replacement for the resistor in a CRC power supply - R21 PS module

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Reactions: Msander68

Lundahl Chokes, Input and Output Transformers

These are all unused and never mounted.

Power Supply Chokes
2x 3H/500mA - 120 (pair)
2x 6H/250mA - 120 (pair)

Line Level Transformer (Sold)
2x LL7903 - $200 (pair)

Output Transformer - (Sold)
2x LL2745/8mA - $150 (pair)
The LL2745 is a specially designed line output transformer for O1a and #26 directly heated valve preamplifiers.

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Help with passive volume attentuator (passive preamp)

Hi out of curiosity I decided to try a passive volume control.
The reason was to see if the cd via a dac could drive my amps.
I was hoping for a greater sound stage.
I read as many threads etc i could find on the subject and understand there is a relationship between output and input impedances
Due to that fact and not fully understanding the concept I ordered the cheapest passive I could find thinking if it worked I could change the pot, connectors and rewire for greater clarity overall.

The cd player Rotel RCD02 is listed as 10Ohms output
The dac CA Dacmagic outputs <50ohms 2.1v
The Power amps 2x bridged mono Rotel RB03 input sensitivity is 33kohms 1.0v
The RCAs are Cable Talk Monitor 3 all quite short
The pot used (allegedly) is alps rk16 10k

Plugging in last night I definitely fall into the HF roll off camp so not one to give up just yet I am curious.
The set was able to drive volume with no problems, however there is definitely a drop in HF I understand this should be due to impedance matching.

Is there a way to modify the source, cd and/or dac output or the power amps input to improve the matching which would not detrimentally affect the system if it still is less than favourable?
I'm quite comfortable swapping out caps/resistors.
Could some diy low capacitance interconnects help?
Does the pot have any effect? e.g swapping to a genuine alps rk27 with point to point wiring and better RCA's
Or is this simply a its not going to work scenario?

Thanks in advance Ian

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CARVIN TRX-18; a good enclosure for Home Theatre?

While searching for large amplifiers to begin a journey towards large subwoofers for LFE and musical enjoyment, I cam across a deal for 4 (FOUR!) large Crown amplifiers, 2 CE2000's and 2 CE1000's, included were 2 CARVIN TRX-18 dual 18" subwoofers. I wrote a check and hauled it all home on a trailer.

Yes, they are comically large. As I pulled them up the front stairs, my girlfriend says, "You don't want to be married, huh? " - Nope. LoL !

So, I hooked up both sets of twin 18's, and set one CE2000 on each box, bridged to 4ohm, for a 2,000W RMS potential. Plenty.
I added a ROLLS box to take the RCA to balanced XLR input with a DSP-LF box upstream of that.

My SONY SNR-DN1080 has dual Sub outputs. I cut off those big JBL dual 10's at 120hz HP in the Sony and then manually X-over the big subs at 120Hz LP in the DSP-LF, (plus it's own driver, enclosure, and room correcting autotune).

Deep bass and LFE is amazing.

Question 1; What type of enclosure is this CARVIN TRX-18? It has two openings for each 18, yet it is not a port. A infinite baffle box?? 🤔
Question 2; Having way more power than I need, would I be better served building a sealed or ported box with these 18's ? - or selling them and starting from scratch on a large 18 or 21" based sub enclosures.

Thank you for any advice!!
-Paul

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Dayton ND25TA Titanium Dome tweeter

Anyone had any success using this tweeter?:
https://www.daytonaudio.com/images/...me-neodymium-tweeter-4-ohm-specifications.pdf

It's been a couple of months, but I tried this out crossed at 4KHz 2nd order, and frankly it sounded bloody awful. I perhaps should have padded it down a bit more, but wasn't motivated to try. Any hints for improvements, before I consign them to the outer darkness? I bought them based on price, dispersion looks good, & they've got an integral grille. Perhaps the peak in the high teens needs taming, but at the moment they're just confirming my prejudice towards soft domes.....

Sound Cuts Out - Low sound causes it to cut out

Hi there,


When movies have a quiet scene - the sound from the soundbar cuts in and out. Does anyone PLEASE have a fix?

We maximise the laptop/chromecast volume, then control the soundbar volume from there.

I have a TV - Chromecast 3 HDMI plugged in - and the below sound bar connected to the TV with an optical cable.

Panasonic 200W 2.1 Soundbar w/ Wireless Subwoofer
SC-HTB488GNK

The TV is quite old - Panasonic TH-P42S10A.

Oppo Resistor Identification

I have an Oppo DV-981HD dvd player. the player stopped working so I decided to open her up for a look. There is a burnt resistor in position R511 on the power supply board. Since the resistor is burnt I can't read the value. I searched online and no schematic available. There are two colors at each end that didn't get burned. One is gold and the other looks like dark green or black. I tried a suggestion to put a multi meter on one of the leads and the other just before the break in the wire. Repeat on other side. Add the two together and you would be close to the value. The problem is that there is no visible break. I get a value on one side and the other side gets no reading. The exposed core looks like it has a spiral winding. Can anyone help with this?

Thanks

class-D Amp for Bi Amping a Woofer in a 3-Way

Hey there,
i am trying to find a Amp to drive a woofer which i would like to add to a 2 way system. the 2way should be driven from a valve amp, KT88pp, and i am thinking of adding a woofer like the faital 12pr300 for low end extension.
The two way could be driven with its passive crossover, maybe a active highpass added.
i have also seen some regarded designers following this setup, and it would be a great starting point to play with class d and an active xover.
there are lots of people going for a hypex modules, but there are also some suggesting a IRS2092 sounds better (and costs substantially less).
What surprises me is that a lot of people seem to be happy to simply order some ready made "modules" from china but i wouldnt mind a bit more diy.
is it worth building a class d amp? the L15D seem to come at less than20€ each and i dont seem to be able to even find the chips😕,
any opinions?
cheers
Juergen
Merken

What are the best options this year for dome midranges?

Hi all,

I am building a large floorstanding box with removable baffle that will house several different drivers and topologies, first a 2,5/3 way with AL170*2 AL130M and waveguided tweeter. Another speaker that will be built on another baffle is a 2,5 way with 8" HDS 830869*2 and waveguided tweeter, and when im satisfied with the HDS speaker an idea i got was to try out a dome as a midrange between the 8's and tweeter that possibly not going to be waveguided.

Tweeters intended to be tested are my current HDS tweeters in my Elsinore's, SB26ADC, SB21SDC and hopefully also the new DA25BG08-06.

The idea behind using a dome mid os to try out a speaker that is spreading as wide as possible as high up in frequency as possible and to see what that does to the sound against the more common controlled directivity a waveguide gives, as this might be hard to comprehend but all my speakers i have own have had some form of waveguide.

But whats out on the market thats is good? And hopefully somewhat cheap? Lets say preferably under 100$/100€ but if something a bit more expensive is really good then please post it!

Also please post your input on use of the driver and what you think about it!

Best regards from a cold place where the winter is coming...

AB International 713A amps with built in active crossover

Hello there;

I own some AB International 713A amps with built in active crossovers.
I want to change it from 3-way to 2-way like the model 712A.
Does anybody know or own a model 712A to give me some info on the jumper settings of that crossover-pcb.
Seems like the pcb is standard for all models ,just the jumpers change.
Thanks in Advance;

Jorre

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Epos ES14 2-way Refit Project

I want to put a 2-way kit into Epos ES14 boxes and stumble on a respectable system. See poc - should be able to mount drivers on baffle and screw in

Facts:

° LWH = 12”x9”x19” (20+ liters?)
° Ported in back
° Internal metal bracing
° Simple banana plugs
° Have 80 watt Sony TA-F500ES amp
° Also have ~1962 HK Citation II awaiting McShane rebuild - so tube friendly good

Boxes obviously don’t deserve $1k kit. And I’ll initially have them in corners…haha I don’t care. But occasionally out in “display”.

So I’m hoping to get drivers for cheap. Will adopt used ones from a loving, non-abusive home.

But what?!

Idunn, rediscover ii, sr71, etc? Emphasis on spopranos-basses, and pianos. No ice picks - my ears are…seasoned!

Peace and love to you and families.
Cjrtrio

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which opamp for active crossover

Hi guys,
Am planning to build this: Linkwitz-Riley Electronic Crossover still working on the pcb layout.
I am on a college budget and i have a choice of three opamps:NE5532,most expensive and is recommended for the job;TL072,cheaper than the NE;and a "4558",the cheapest option and is flooding the market,used in most electronics from china.
Which will sound decent among the three without eating into my wallet?

Has someone built this phono stage?

Hello. After some time away from DIYAUDIO, here I am again.
I revive the question asked a few years ago.
It's about the phono preamp posted on TNT.
Solidphono TNT. (They say it is based on the Lehemann Black Cube circuit)
I have built it many years ago and it seemed excellent in its performance.
But I have found a post of a phono pre based on this one from TNT. But with the RIAA network divided. It is still passive RIAA, with some different value. (I have simulated it in LTSpice and the response is almost flat)
I have built it but using the IC THAT 1510 in the first stage.
Of course on homemade PCB.
Sounds like a very good phono stage to me. One of the best I have ever had.
Here I return to the question:
Has someone built this phono stage?
Someone is encouraged to test your construction and see if I am right that it is good?

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For Sale Battery Powered MM Phono preamp

MM Phono preamp. DIY. Uses 4, 9 volt batteries. Opamps are AD712JN. Angel Polypro output caps. Gold RCA input and output connectors. XLO signal wiring. Silver mica and Polystyrene RIAA caps. Carbon film resistors. Great sounding simple RIAA stage. 50db gain. Will accept High End Audio DIPs.
Top has some scratches from use. With a little paint, it would be a 10. Will ship w/o batteries to avoid extra weight and hassles with shipping batteries.

Asking $75.00 obo. Shipping CONUS only.

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Would combining stereo signal pairs in a single cable reduce potential ground hum?

In the article How To Wire an Audio Amplifier by Andrew Russell, the author advises minimizing the separation of single ended interconnects to minimize loop area that can be affected by magnetic fields. Carrying this to its logical conclusion, would not a single cable with four conductors provide the optimal loop area? I've never seen a single-ended cabled designed in this way, besides phono cables with a 5-pin DIN connector on one end. Why not expand the concept to an entire system?

A tangential tracking pivoting tonearm

I want to present a version of a pivoting tangential tracking tone arm. I will firstly describe the theoretical model without addressing the engineering implementation.
I have pored through the threads on DIY Audio concerned with related technology. I can’t find any projects with precisely the same viewpoint as put forward here but I may have missed some threads. To be absolutely clear, I won’t be discussing a parallel tracking tonearm, but a version of a pivoting tonearm that maintains tangency of stylus in the groove.The tonearm will experience no side thrust and hence will require no anti skating device.

The proposal will not rely on a pivoting cartridge headshell. Tangency can be enforced purely passively with no servo involved, although a servo version can be implemented.

I have tried to keep the principles close to fundamentals, so it can be clearly understood. In the interests of clarity I will present the proposals in a series of posts, each building on the previous, and illustrated with simple geometric diagrams.

I am not yet in a position to engage in detailed debate concerning the practical implementation. However I do welcome any constructive advice. In a later post I will show some videos of a basic working model.

CDM4/19 based Technics CD player and old CD-R discs

I'm trying to fix an old Technics SL-PJ27A, nothing fancy, just a basic CD player from early 90's. It is based on the Philips CDM4/19 mechanism and so far i had little problems with players based on such swing arm mechanism. This player indeed works perfectly with stamped CD, but with CD-R it can have problems: it reads the TOC with no problem, but then when playback starts it seems as if it is not able to correctly lock on the track and the arm is swung back and forth with the head hitting the plastic wall near the spindle motor. Once it locks on the track, it then plays the CD with no issue from start to finish.
I have already replaced the faulty Philips electrolytic caps in the servo board and both laser power and focus offset are correctly adjusted.
What could be wrong in this player ?

thanks

I'd like to build sub using three AC8D's, should I build a sealed sub if I don't have a detailed plan for a triple box

Planet audio has the specs for a single box...
Ported Dimensions:
Length (L) : 14”
Width (W) : 12”
Height (H) : 12.75”
Port: 11.25” x 1” x 22”
Port Extension: 10.125”
Port Tuning: 40 Hz

Following the measurements the opening leading to the port is only 3/4" and the port is 1". This seems off so I would like to use WinISD to come up with a design but I can't find the electro-mechanical measurements anywhere. Is there any decent 600w 8" subs in the $50 price range?

Permeability of MPP core?

Hi,
I am going to wind a toroid inductor for this circuit,
but would a high permeability core of this type have any downsides?
And is 34 AWG wire fine for this?

Info on core:
Core type MPP
OD 39.90 mm
ID 24.1 mm
HT 14.5 mm
AL value: 740 +/- 8% (nH)
MPP Permeability: 550 (μ)
Wire gauge: 34 AWG

Turns:
16 KHz - 29.9 mH 195 turns
10 kHz - 31.4 mH add 5 turns
8 kHz - 48.2 mH add 48 turns
5 kHz - 67.5 mH add 45 turns
4 kHz - 87.9 mH add 41 turns
3 kHz - 156 mH add 111 turns

Inductor-schematic.png



Help is much appreciated!

Mac audio device to deliver uncompressed 7.1.4 to avr

Hey gang,

New here. Looking for some guidance I’ve not found anywhere else…

I’m an audio mix engineer. I’m putting together a home theater setup that I’d like to be able to act as a secondary workstation to my studio and am trying to figure out a clever, cost effective way to pull it off. Here’s the deets:

I’m branching into atmos and spatial mixing this year. My studio will have a proper atmos mixing setup. At home, Im putting together a home theater setup with an Oled + atmos capable avr + 7.1.4 speaker setup. Ideally would like this to stand alone without building it around a computer in any way. BUT…I want to find a way to loop my 2019 MacBook Pro (Big Sur) into the setup and mix/monitor on the 7.1.4.

****Important point: though I’m mixing atmos in the daw, my DAW will NOT be outputting a Dolby atmos stream. It’s not an option even if I wanted it. It will be outputting a decoded stream of 12 discreet, uncompresssed channels…7.1.4. And it’s this 7.1.4 PCM audio I need to get over into my AVR somehow.

The problem is (short of spending thousands and thousands more I cant afford) I can’t figure out how to output that many channels to an AVR. I’ve got tons of experience with audio interfaces, but none with avrs and hdmi type connections. But seems like it must be possible somehow…

Things like hdmi 1.4, coaxial, optical etc reach their channel limits topping out at 8. But e-arc hdmi is capable of tons more bandwidth…up to 32 channels of audio. But I have no idea how to package the 12 channels of pcm I have and deliver it.

FYI, the AVR I’m leaning toward is a Tonewinner at-300. It does everything I need, including providing the right analog outputs IF I can just get the mix over to it. https://summithifiusa.com/products/at-300-16-channel-pre-pro-releasing-soon

I’m open a variety of solutions like: a virtual audio device that outputs to some sort of converter to earc, an inexepsive piece of hardware/interface that does similar, another AVR altogether…something else I’ve not thought of that meets the goal.

any ideas?

Big drivers for sealed subwoofer but with good sound up to 100-150Hz

New project - inspirated by DynamiKKs Monitor 12/18.
Speakers: one coaxial 10-12" and woofer 18" or 2x15" in sealed box. I like quick bass with a punch 🙂
Active powered by Hypex FA 503 with build in DSP (or FA 253)
What woofer will be best for low bass up to 100-150 Hz? Typical great subwoofer like Dayton RSS460HO-4 18" Reference HO I think will be not good sounding up to 100-150 Hz - or Am I wrong? Any propositons for good soundings coaxial?

Best so far:
FaitalPro 18XL1800 (F3 55 Hz in 95 dm3)
BMS 18N862 (F3 55 Hz in 95 dm3)

Coaxial likely:
BMS 12C382 (F3 136 Hz in 11 dm3) This one need woofer working well up to 130 Hz or so
FaitalPro 12HX230 (F3 94 Hz in 40 dm3) This one need woofer working well up to 100 Hz or so
B&C 12NCX (F3 88 Hz in 60 dm3) This one need woofer working well up to 100 Hz or so

DynamiKKs Monitor 12/18 (bass-reflex)
speaker-1.png

What is wrong with TPA3255?

Hi,

I have tried a bunch of TPA3116 amps...they all sound OK, some sound very well...

I am ready for the next step in class D amplifiers, thats how I found TPA3255...specs look very promising.

I could not find any DIY boards so I ordered TAS5630B instead...not my cup of tea...to noisy. (I hear a white noise in my listening chair)...

I was wondering why I could not find any DIY boards based on TPA3255...

Any hints?

kind regards,

Tony

NAD C356BEE (Missing -18 Volt rail)

Hi Members,

my new NAD adventure with this amplifier that seems to have very fragile traces and solder points has started.
The unit turns on fine, amber LED on then click, click Blue LED stable.....good news.
DC Offset is on the high side, one channel 50 mv other one 100 mv after 10 minutes (not able to adjust it at all).
BIAS Current is good (6 mV) and fully adjustable.
I suspect that somewhere in the feedback circuit something is wrong.
Upon inspection all voltages are present except the minus 18 V and -26 V rails.

I pulled the LM337M and tested it separately in a small circuit to verify that it was working.

Refer to attached pictures, appreciating any feedback.

Thanks

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Favorite Threads and Posts in "Pass Labs"

Favorite Threads and Posts in this Forum

This permanent thread is a place for links to threads or posts in this particular forum that are useful and/or exemplify the best of DIY Audio.

This is so others- especially newer members can find them. Feel free to post with these links and a brief comment on what the thread discusses Occasionally the moderators will consolidate them into fewer posts.

Denon PMA-2000ivr Amp cuts out, need advice

Hello everyone,
I've had this Denon PMA-2000irv amp from new in 1999. Always well cared for. Wonderful amp, great sound. Love this amp.
However it has developed a couple problems. I believe they are not related but I'll describe both just in case.

The main problem is the amp will just cut out completely for just a couple seconds and then click back on and perform fine. It does not happen very often and when it does it may do it a couple times and then go away. Amp works fine for a week or so and then does it again.
It has a main power button which when pushed in can be shut down with remote. Amp goes into sleep mode with the button pushed in but still consumes power.
I always turn the amp on and off with the button, never leave it in sleep mode.

The other problem seems to be with the selector switch for aux/tuner/phono/cd/etc. Sometimes it will suddenly change selection, clicking from cd to tuner, etc.
I figured it may have something to do with the remote mech and have covered the remote IR sensor with black tape. This seems to have stopped the problem.

I've had the cover off, everything looks really good, very clean, no outward signs of bulging, etc.

I live in a fairly remote mountain village and the closest Hi-Fi repair shop is in Calgary Canada, a full days drive away.
So my main question is if anyone has an idea what the trouble is and whether it's something that can still be repaired these days.
Cheers!

Unused pin 866A

Quick question(s). Can I use one of the unused socket pins on a 866A for a lug to extend my HV going to the top cap? Just 1 & 4 are for the filaments. 2 & 3 are unused so I was hoping to use one of those as a terminal. Related question is how far away from the surrounding metal structures would be a safe distance assuming a working voltage of 450V? Currently, I have about 0.1" or 2.6mm.

Another TC-750 question on mods...

I've been playing with a TC-750 preamp.

I found this guide on modding it: https://www.superbestaudiofriends.org/index.php?threads/tc-750-phono-pre-amp-continued.150/

I've removed the 220pf input caps (circled in green in my included schematic), as I don't need any additional capacitance, I rely on whatever is provided by my cabling. I do have a couple of test records with pink noise, and I can confirm my response is very flat (+/- 1db) out to the limits of the album and my ADC (typically 20k).

In one of the comments, someone mentioned they removed the 1k input resistors (circled in red). I had tried this but thought I was getting more noise. As it turns out, my noise may have been induced by power/cabling issues. But, I did put them back in.

My Q before I try removing them again is, does anyone know what function they may provide, and whether removing them is indeed something that may reduce noise?

TIA for any help.

tc-750_mods.jpg

System two SYS-2322 digital input dead

So my Christmas present this year is the digital input of my system two 2322 dying with no prior notice.

During a routine self test it did not recognise any of the 3 possible inputs (BNC, XLR and Toslink) and threw "check connections" error. In normal instrument operation digital input voltage readout is always few millivolts. Only exception is BNC to BNC (cable loopback) when output is set to 2.5Vpp and Hi-Z the input readout is 2.9Vpp (?!), at 2.2Vpp output readout is 1.9Vpp and below 2.1Vpp output readout is always few millivolts. No more working (always few millivolts) if set to 75 ohm. The same with no cable connected an GenMon input or any other combination XLR and Toslink. It looks there is a kind of crosstalk because if I connect BNC to BNC and set input to XLR I still say valid data but voltage is, again, few millivolts. I probed the output of digital generator with an oscope and signal is OK.

So I am starting checking for any clue. I noticed on the digital connectors board there is a MAX310 multiplexer. Should I start replacing it? I know there are very competente users about AP old stuff. Like Audio1Man user. So it's great if someone could put me in the right direction.

Lack of schematics does not help for sure.

Thanks!

Building the 7pi (seven pi) speakers - Spring/Summer 2021

I wanted to upgrade my stereo system downstairs hoping to eliminate the effect which always reminded me where the sound was originating. My previous speakers were a pair of Sound Dynamics 300TI, which I like very much and worked very well in the room. However, I have a pair of BassZillas in my system upstairs, which create a huge sound stage. I was hoping for something similar downstairs despite the space constraints.

After researching for a while I decided to build a pair of Pi Speakers 7pi.
I have just finished building them and am delighted with the results. The 7pi creates a large sound stage, much bigger than the room where they are located.

Many thanks to Wayne Parham for sharing this great design.

Here are some pictures of the build. I designed my own crossover PCB just as part of the enjoyment of building my own speaker system.

attachment.php


Also built a case for it.

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Here is the crossover encased

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To fit behind the mid-horn I added a base to keep it vertical

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This is how the crossover sits on the bass unit

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Source follower buffer/ccs implemention

Hi All,

Hoping for some advice with my current build. I am intending to implement a source follower buffer/bootstrap CCS for the input and driver stage, a bit like the below image.

Due to the heatsink configuration, I am limited to a about 2W dissipation in the FET, which means I can run it at 10mA or so.

I was hoping to run the 6SN7 at 10mA also (200V at 10mA looks like a real nice operating point under constant current conditions).

It occurs to me that perhaps the bootstrap won't work well supplying 10mA with only a 10mA sink capablity in the follower, i.e. the follower should possibly be run at significantly more current than the 6SN7. Is this a valid assumption? Not sure I completely understand all the factors at play.

I am pretty much locked in to 10mA in the follower, so the alternative is to run the 6SN7 at 5mA or so (with 20k load resistors).

Appreciate any thougthts you might have!

Greg



source follower.PNG

InDIYana 2022; "Missing Link" competition included....

InDIYana 2022 will be Friday May 6/Saturday May 7. Pertinent info at the website link, and is most concise as to needed information.
Information to be updated as it happens.

We are having a 'Voicing Day' In LaPorte on Jan 29th, see posted address on website.
We are minimal in RSVP at this point for Voicing Day. Just 6 of us. Please let us know if you are coming.
https://sites.google.com/site/indiyanaevent/
To Download measurement file for Missing Link competition/challenge, see event website or look here:
https://diy.midwestaudio.club/discussion/1769/indiyana-2022-missing-link-theme-announcement/p1
For those whom are international and want to be included in the challenge, please contact Mark at Meniscus.
Please register and let us know if you want to attend,
Wolf
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Replacements for SA1941 and SC5198

Hi All,

Repairing an Onkyo receiver. Shorted output transistors. Both an SA1941 and SC5198, which are obsolete. Interestingly, the schematics for the device list Sanken 2SA1695 and 2SC4468, which can be had. But some other threads have indicated to use Fairchild FJA4210OTU and FJA4310OTU. Anyone got any opinions on which? Price is comparable, the biggest diff is Digikey sells the Sanken's, and Mouser sells the Fairchild. Specs look similar enough.

Lovoltech LU1014 Power Jfet Group Buy

Group Buy signup sheet


With Zen Mod's recent news of the LuDEF amplifier concept, there has been renewed interest in the Lovoltech LU1014D power Jfet. Papa first used the LU1014D in the Zen Variations 8 & 9 and then in the First Watt F3.

Links-

First Watt F3

Zen Variation 8

Zen Variations 9

LuDEF

The LU1014D has long been out of stock and joined the list of power Jfets (SemiSouth R100) that we all want to buy and use but can't seem to find.

Luckily for us, a certain benefactor (initials are NP), has a stash of the LU1014D that he's agreed to make available to us through a group buy. A few members are working out the GB details currently- cost, shipping cost, sign up sheet, etc... and we expect to have the details on this thread shortly.

It will be an international group buy and we expect to have enough supply to fulfill demand.

If you haven't seen an LU1014D, I've attached a photo with an IRFP240 for comparison. They are tiny.

FAQ-

What can I build with the LU1014D? A- An F3, ZV8, ZV9, maybe a LuDEF. Schematics are all on line. Or maybe design your own amp.

Yeah, but there's no PCBs for those amps. A- True. Maybe we just need to sprinkle a few LU1014Ds around to get members to create a few gerber files. Seemed to work with the SemiSouth giveway. There's a few new Aleph J pcbs, plus renewed interest in the F1 and F2. Why not the F3?

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Synergy attempt without compression driver

I've been intrigued by the Synergy concept for some years but have some resistance against using compression drivers. The very high sensitivity makes them noisy with my amplifiers. But primarily I've gotten really nice results with the ScanSpeak R2604 in a waveguide which makes me want to try it.

A first sketch:
530212d1455107911-synergy-attempt-without-compression-driver-r2604-synergy.png

Inside. The woofers are Faital Pro 8FE200.

530213d1455107911-synergy-attempt-without-compression-driver-sketch2.png

Outside view.

The size is about 50 x 35 x 30 cm (W x H x D, 20" x 13" x 12"), i.e. a quite compact synergy.

These are the horisontal polars of the R2604 in an early waveguide (210x130x85 mm):
An externally hosted image should be here but it was not working when we last tested it.


KpluznBl.jpg

Measured waveguide (the brown one).

530214d1455108141-synergy-attempt-without-compression-driver-r2604-wg-raw.jpg

On axis, with phase.

530215d1455108141-synergy-attempt-without-compression-driver-r2604-wg-lt-peq.jpg

On axis with PEQ and LT.

530219d1455108855-synergy-attempt-without-compression-driver-r2604-wg-lt-peq-impulse.jpg

On axis with PEQ and LT.

530216d1455108141-synergy-attempt-without-compression-driver-r2604-wg-dist-85db.jpg

Distortion at 85 dB with 1.2 kHz bessel (for Harsch XO).

530217d1455108141-synergy-attempt-without-compression-driver-r2604-wg-dist-94db.jpg

Distortion at 94 dB with 1.2 kHz bessel (for Harsch XO).The R2604 should be better loaded in the bottom end with a 50 cm wide waveguide (synergy horn) and that should reduce the distortion to enable a 1.2 kHz crossover and 95 dB maximum level.

The plan is to 3D-print the first part of the horn (throat) and then use wood for the last part.

I'm quite new to Hornresp, but have tried a little:
530224d1455109880-synergy-attempt-without-compression-driver-hornresp-input.png


530223d1455109775-synergy-attempt-without-compression-driver-hornresp-power.png


Throat velocity (separate model) is 9 m/s at 2.83 V and diaphragm displacement is 1 mm. I've used 2 x 1" holes for each woofer in 19 mm MDF using minimal volume filler (measured the Vtc for the woofers at 350 ml).

The plan is also to have a leaky supercardioid setup for the woofers to stretch the directivity of the speaker down to below 200 Hz.

I'll post 3D-models later to show what I plan to print 🙂

/Anton

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Finding the right amplifier for my 3-way speaker

Hello to everyone! I'm really new to the building of loudspeakers and I've decided to build a 3 - way speaker. I picked my drivers from Dayton:
Subwoofer: RSS210HF-4 8" Reference HF Subwoofer 4 Ohm RMS: 280 watts
Mid: PM180-8 6-1/2" Neo Wideband Midbass Driver RMS: 30 watts
Tweeter: ND25FA-4 1" Soft Dome Neodymium Tweeter 4 Ohm RMS 20 watts

I designed my crossover on vituix and I've attached my design.
微信图片_20220112172945.png
微信图片_20220112172958.png
微信图片_20220112173009.png
微信图片_20220112173015.png
微信图片_20220112173021.png
微信图片_20220112173026.png

My questions are
1. What exact amplifier should I get? I've read so many articles about this and was still unsure: Some say 2 x the subwoofer (which in my case = 560 watts) I am afraid that it might burn my tweeter. I've originally decided to use one amp to power all but if not possible, will two amps affect my crossover? If two amps are a better choice, which ones should I get and how should I connect them together?
2. I've noticed that the lower end of my impedance dropped to about 3.5 ohms, Is that a bad thing?
3. Is my SPL curve good enough? IF not please let me know which part needs to be improved!
4. If there's anything ridiculously wrong in the charts please let me know that as well!

Thank you all for your time!

Weird Kitty Hawk M1

A while back I bought a Kitty Hawk M1 amp.
However, I soon saw that this implementation deviated from the schematic that is circulating on the internet:
http://www.kittyhawkamps.com/schaltplaene/m1preamp.jpghttp://www.kittyhawkamps.com/schaltplaene/m1_m3_endstufe.jpg
What immediately strikes me is the combination of EL34 and 6L6 power tubes.
In addition, I did not have the switch to switch between EL34 and 6L6 and the Class A / AB switch on the front was also missing.
In short, time for reverse engineering.
Preamp.png

Poweramp.png

Power Supply.png


This does deviate from the M1 schematics that is circulating on the internet.
There also appears to be a tda2030 for the reverb.
The main thing that stands out is the power amplifier.
There seems to be a gain stage after the phase shifter. Has anyone seen this before?
As mentioned before, there are 2 types of power tubes in the power amplifier. Namely a pair of EL34 and a pair of 6L6.
Now these all have the same bias voltage and anode voltage. This doesn't seem right to me.
Then measurements were made on the power tubes. Below the result.

V7 - EL34
V8 - EL34
V9 - 6L6
V10 - 6L6

V7:
60W 81mA
120W 67mA

V8:
120W 68mA

Q9:
120W 52mA

V10:
60W 74mA
120W 67mA

Measurement on tube V9 deviates a lot from the rest.
Switched V9 and V10 for the test and did another test on the position of V10.

V10:
60W 60mA
120W 50mA

Doesn't seem like this tube is completely within spec?
And the rest of the currents, aren't they set very high?
For example, if I enter the data for an EL34 on this site: http://mail.robrobinette.com/Tube_Bias_Calculator.htm I could get about 38.9mA at 70% disipation.
This makes a significant difference.
In addition, the settings for both EL34 and 6L6 appear to be equal with the same bias voltage. This isn't quite right either, is it?
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