Hi,

I`m looking for a Denon Au-300lc in good order condition. Or Denon Au-320, as alternative.

Thanks,

David

I have finally finished the setup of my horn system.




Here is a measurement at listening position. Looks fine.

Hi,
I am an idiot. I am enjoying my DENON DVD2900, so I thought I would get another one. Being an idiot, a broken DVD2800 turned up, duh. It has the nice HDCD device in though. It didn't recognise disk, so I got a new laser off ebay (being an idiot) and have now fitted it.
To my surprise it works, sort of.
Put in a pristine CD and will load up and play sometimes quickly sometimes less.
Put in a less than pristine CD and sometimes it will load and play happily quickly and sometimes not atall.
Put in a playable but pretty damaged CD, chuggs and spins, doesn't play.

So it seems to be sometimes struggling to read the disk. When it does, it plays fine all the way through and skips between tracks quickly.

Powering up and opening and closing the door seem to be the things that affect the how well it recognises / reads the disk.
The service manual is not very forthcoming,has a few pictures of what happy disk loading ought to look like but no corrective measures, there are no tweaky pots, just mechanical adjustments, and all the test points are under the transport. So I haven't successfully looked at them on the scope yet.
The power rails look ok enough 5v rails vary between 4.5 and 4.9.

I am tempted to try replacing a few strategic PSU caps (I am a professional (idiot) I won't kill myself) just incase and investigate the power rail voltages a bit further.

Any bright Ideas?

thanks

Just trying my luck to see if anyone has a used Toroidy 0250/001 power transformer for sale.

Shipping to New Zealand.

Thanks 🙂

Anybody can help.

I need schematic 6sn7-45-IT-300B

Many Thanks


Regards


Hendra

It's a bit of an apples to oranges comparison, but any thoughts/biased opinions on each of these speakers? I am very impressed with the reputations of the men responsible for each, and the actual/potential performance of each speaker. Yes, the Statement II has a track record, and the BMR Tower is new on the scene, and yes, one speaker is a major diy project and the other is a finished product.

Assuming I had the means to properly build the Statement II, and I wanted to achieve the highest quality audio along with high spl output, how do you think the two would compare when used for the purpose of 2 channel music rather than HT?

I would like to preface this inquiry with the intention of not denigrating anyone.

https://www.stereonet.com/forums/up...FD.jpeg.fcc0c78d312e9009542b48c79802f8d3.jpeg

https://www.philharmonicaudio.com/images/BMR-Tower-Rosewood-2-smaller.jpg

Amp turns on and plays audio but at a reduced level. Goes into protection when input level is raised. Amp has signs of heat and a burnt resistor on the input board. Replaced the burnt resistor but problem is obviously still present since I didn't repair the cause. Any help on where to start would be greatly appreciated

Hi There! This is my first post. Brief introduction i have a pretty basic and limited knowledge of HiFi equipment and a fairly basic understanding of electronics (always keen to learn though).

Recently went out and bought an Onyko A9010 Amp and a set of Q Acoustics 3020 only to be left underwhelmed by the speakers performance i started remember my love for older HiFi gear and headed straight to Ebay, Google and Gumtree to see what i could find, a few days later i had a pair of very nice coniditon Technics SB-X3 speakers for peanuts. Got them home and plugged them in and on the whole was fairly impressed with their sound.

Not being satisfied i got the tinkering urge and started to pull apart check the internal speaker connections, crossover, and to give them a general spruce up. I them started reading into the capacitor replacement for the crossover and that generally electrolytic caps are bad past 20 years or so. So having never modified a crossover ever i started googling furiously for the types of capacitors to be hit with a minefield of options, prices and types. The SB-X3 crossover features 4 NPE's, 4 Inductors and one Wire Wound resistor in series with the woofer cap. From my week of googling i opted for some Ansar Supersound polypropylene as its suggested they are vastly superior to any electrolytic capacitor in an audio path and they sat at a reasonable price point.

I have just soldered them on today, expecting to be greeted with an uplift in treble brightness and clarity (seems to be the main enhancement NPE vs poly), but only to hear a muddy ruined speaker.

Hours and hours of head scratching and checking soldering i cant figure it out guys. With the new capacitors in place the Mid cone and tweeter's output are effectively reduced by 50-75% over NPE's. More research and reading into ESR issues on Polys vs NPE's i then decided to add an inline wirewound resistor in series with the cap, i tried 0.1, 0.22, 0.5, 1.0 Ohm and none made a discernable difference. THe woofer output seems unacfected and the volume seems inline with normal on the Poly cap, although people seem to leave NPE's for the woofer and use Polys for the tweeter i just decided to renew them all. I have bypassed the speakers mid/tweeter attenuators and that also made no difference.

Where am i going wrong guys? I don't have the knowledge to know what to probe or how to trouble shoot futher. I want to make it work.

I Have attached some pictures of the Crossover. The link to this manual shows the crossover schematic and PCB layout. Thanks for any help you an offer!

Technics SB-X3 - Linear Phase Speaker System - HiFi Engine

TECHNICS SB-X3 - Service Manual Immediate Download

Hi I'm designing a box with 2 Dayton RS150T-8 (40W each) in parallel combined with a passive radiator. (and a tweeter but not important here 🙂)

What I'm now seeing is that at (very) low input (10v) 25W the basta simulation excursion graph show that I'm at Xmax ? Actually much earlier if I take the frequencies lower than 44 Hz into account.

Anybody willing to explain this please ? (I can reduce the box Vb but then the charterictics are way off) ps, vent / passive radiator are exact as per vendors parameters. (SB15SFCR-00)

Thx !

Hi all

I have two identical toroidal transformers. Purchased on the same day, so probably same batch.

They have 2x 115V AC primaries, and 2x 15V AC secondaries. I need to find a way to double their voltage, while keeping them in the same common supply. Each one is capable of 15VA.

I was playing around in the software, and came up with two different combinations. See the Imgur link here.

Please let me know which would be the best method to connect the primaries.

In a weak moment I bought this pcb from ebay:
1 Stück vergoldet EL34 Push Pull Röhrenverstärker tube amp DIY PCB | eBay
It has a 5751 as input tube and ECC82 as longtail splitter.
I am going to change the Ecc82 for a ECC99 or a 6CG7 and a CCS.
But is the 5751 any good for input tube for hifi?
I have seen some use 12AT7 as input tube,but I don´t know..

Hello! I need a phono preamp circuit on nuvistors - I want to make such a device for myself . Can anyone suggest such a scheme? Perhaps - someone has already made such a preamp and got a good result. I will be very grateful for the information .

A FaceBay sale and I just collected. I thought it was worth taking a chance on a 20 minute drive and a $20- sale.
One of them is a decent enough generic 10" 4R woofer but the other.
It's a Paradigm in excellent condition.
Looking now for any information on the Paradigm B156 WFP Also note some extra numbers on the sticker W02200
Cast alloy frame and a poly cone with stiffening ribs and about 15mm of travel. Dusty and needs a clean but measure 8R

I sell three different condenser microphone amplifier modules for Chinese BM-700, BM-800 or similar microphone body on eBay:

1. CM-1A (Starting lvl);
   
2. CM-2A (Middle lvl);
   
3. CM-1XP (High lvl).

Compatible capsule: 34mm condenser capsule or 25mm electret (without built-in JFET). Required 48V phantom power.

Amp powers up and then goes into protection mode .

I noticed I get 7 volts of DC measured directly across the speaker terminals when the amp powers up

All the outputs test fine .

Any ideas ?

what can I expect the sonic differences to be between the SEAS 27TBFC/G and 27TBCD/GB-DXT? I would like to make a two way with an 8 inch woofer.

Hey All

Selling one complete (but unpainted) and two 90% complete Gedlee Abbey speakers (total of 3 speakers). I found out I'll be living in Portugal a good amount of the year, and I won't have the time to finish this system. That's the ONLY reason I'm selling. These were going to be my end-game speakers.

The 90% complete ones are detailed here:

FS: Geddes Abbey incredible speakers DIY opportunity includes speaker stands

Happy to ship via something like uShip. That's how I got the 90% complete speakers and they arrived perfectly at a very reasonable price.

Looking to sell everything together for $2,000. You pick them up in Brooklyn, NY or pay for uShip to pick them up and take them to you.

Thanks for looking!!

-Jim

Pics here:

Imgur: The magic of the Internet

Hello
I would like to ask the forum if you purchased it from Jac music in Germany is reliable? and you ask that because I deposit money for a transformer from 28/03/2014 and despite repeatedly e-mail you've sent I do not have ANY INFORMATION
Thank you

Hello,


I own a Cambridge Audio 851c CD-player/DAC/Pre-amp which I am currenty using av a DAC/Pre-amp.


Lately it has started acting up: WHen powering it on it will produce loud, static white noise. Usually switching it off and on a couple of times removes this problem, and it works as expected after this. However, as this i quite annoying, I decided to open it and have a look inside as the unit is out of warranty.


I inspected the insides and found what appears to be bad capacitors on the power board, which again is connected to the toroidal transformer. The DAC/pre-section looked fine.



I've attached some pictures of the power-board.



Could this be the cause of the problem described?
Could swapping the capacitors be a simple repair?
If so, does Cambridge Audio use "standard" soldering lead, or is there something which I should be aware of?


The values of the caps that seem bad are as follows:
C3 - 15 uF 450V, labeled 1921TQ
C14 - 1500uF 16V, labeled 92GW
C2 - 1000uF 16V, 10IICH


If this might be a matter of simply swapping the caps are there any recommended brands/types of caps or will any do?


I appreciate all and any input, thank you.

The amplifier turns on, the green LED is on, it does not go into defense, but there is no sound in any channel, more precisely, if you bring the speaker to your ear, you can hear the music very quietly. Can anyone come across such a problem or have a circuit for this amplifier? If you need to take a photo, write.

Folks:

I rebuilt a chip amp this past summer (https://www.diyaudio.com/forums/chip-amps/79303-chip-amp-photo-gallery-171.html#post6695088, post #3403) which now consists of a Super Gain Clone amplifier and RJM Audio B-Board diamond buffers and it has been in service in my kitchen ever since. It does two troublesome things: about half the time it is turned on, a second or two later it turns itself off with a loud "thump". By that I mean the illuminated latching power switch actually reverts to its "off" state. The second thing is that when I turn the amp off, it invariably issues a loud thump as well.

Ghosts maybe? A cap across the power switch? Your counsel is appreciated.

Regards,
Scott

I need to socket a Novar tube PCB, but B9E sockets are rare and very pricey.

However B9D Magnoval is in production and available very cheap.

These two bases have identical circle diameters pin center to pin center of 17.45 mm.

But the pins diameters differ by about .26 mm. Novar are 1.02 and Magnoval is 1.27 mm.

I'm thinking I should be able to plug a Novar tube into a Magnoval socket, there should be enough closure in the springs to make contact no? its only .26 mm short.

As long as I never plug a Magnoval tube into it which would then stretch out the springs making the socket too loose for Novar.

For Novar tubes do fellow DIY'ers get good enough contact using the widely available B9D sockets?

Melos tirode 200+ schematics looking for

Hello
I own a Melos triode 200 plus stero and I have problemas with one output (noises and distorsions) and when the problems began the powamp produce a terrible burning smell. It seems a transistor burning smell.
I'm looking for the schematics, but "Melos audio restoration" is closed, Melos audio is closed too.
Please somebody have the schematics?
Thankyou very much in advance
Roberto

Is it really that bad using a sealed sub with ported main speakers, I notice that some manufacturers do it in their ranges i.e. Monitor Audio in the Silver range.

Hi all,

This amp was in protect. Changed outputs and the amp comes on but seeing -1.5v on output terminals without signal. When signal given it is still having same -1.6v but when I increase the gain until it clip the voltage disappears (with no load).

Hello !

Does anyone have the schematic / service manual from Ground Zero GZIA 2230 HPX?

Thanks

This schematic are most likely a earlier version of the well known mullard 3-3 amplifier using different tubes than the the later version we all know real well (EF86-EL84) . This version uses EF40 as the pretube and EL41 as power output tube.

Enjoy 🙂










Btw . There is a third version of the schematic too that uses EF36 or EF37(A) and EL33. But i have not found a schematic yet on this version.

I would like to get polar data for my speakers but a lot of my speakers are large so a turntable is quite impractical. Instead I would like to build a 90 degree microphone arc with 5 degree spacing (18 microphones) at a radius of 3m and use a multichannel interface to capture the sweep. This would look similar to the Dynaudio measurement chamber:
Dynaudio: inside the speaker corp's state-of-the-art measurement facility | Home Cinema Choice

it would be very expensive to purchase 18 commercial measurement microphones, however I have constructed a microphone in the past using these instructions:
System Test
the WM-60AY capsule is no longer available though. Is there a modern replacement? perhaps MEMS?

Hello, i can't hear anyting over 13K... 20€

In fiddling with my composite amp ive found out that two of my toroidals dont sound the same.

One is an antek 300va 24 0 24 0, the other same spec but a local korean brand. They weight about the same. The amp uses lm3886 for output and a simple C filter (not crc)

Simply put the antek sounds much better. The bass is bigger, theres better grip on the lower notes. The korean transformer sounds tinny in comparison as if the power has been halved.

I couldnt get much out of how the korean toroidal was wound except that their core is outsourced (so probably cheap chinese) and they have hum issues (primary wound close to saturation?)

What would differ in a good and bad quality toroidals and how would that affect the bass in a class ab amp?

Thank you for your input in advance.

I’m just trying to get a reference for what more experience people find useful. I’ve mostly been using .075”, but its time for me to reorder and I wanted to know if there was anything else I should try.

My question is: why are all the output sockets I see in all turntable phones all single-ended? Why are they not balanced?

I was under the impression that if

• you have a floating differential signal,
• the signal amplitude is low, thus making it vulnerable to noise pickup

you have a textbook case to want to feed the two wires to a differential input of a balanced or differential amplifier. And I was under the impression that all cartridges, like most (passive) mics, are passive transducers which will generate a differential or "balanced" output. Basically, phono cartridges and XLR connectors and balanced interconnects and XLR inputs to phono preamps seem to be a match made in heaven. This is certainly true about mics and mic preamps.

Yet, I find all turntables fitted with RCA sockets. None of them (that I've seen) are balanced. (I'm sure there are a few, but that's not my point.) Why? Is my understanding of what constitutes a balanced signal incorrect? Is there some other reason why all turntables and phono preamp inputs in the world do not do balanced connections?

I tried searching, but couldn't find anything which discusses this. Maybe my searching was inept.

If you bi-wire your speakers, is it better to remove the jumper cables, or to keep them?

I've been dabbling in alternative technologies for a while now.
Usually they involve gluing 1um thick mylar to something.

I have very rarely been able to make anything close to a perfect diaphram.

For starters getting the mylar to be taught without wrinkles and without ripping the mylar is..somewhat of a challenge.
I currently just unroll the mylar and kind of stretch it out onto a mirror and kind of hope for the best and gently push the wrinkles and bubbles out.

Then I apply super 77 to it and apply the aluminum.

However, this is crude, annoying, slow, and imperfect.

I've tried ordering rolls of metalized mylar from china but they always tell me something along the lines of "sorry this is meant for capacitors" and then shut me out completely, the moment they get a hint that I am doing something unusual which is hard to avoid because they ask for a bunch of capacitor related technical parameters that I don't need or don't understand.
I'm not sure why they just don't take my money...

In any case. How would a professional do this?
Is there some contraption I can use to accomplish this quickly and easily with perfect results every time?

Hi All,

I noticed an ad on FB marketplace that may appeal to someone. This isn't my stuff. I don't know the guy. But I have been super curious about some of these things, so maybe you are too:

JBL 4628B- $300 ea., 4 availablec
JBL 4695– $550 ea., 2 available
JBL 4699B - $650 ea., 2 available
JBL 4625B – $200 ea., 4 available
JBL 4602A - $350 Each, 4 available
JBL 4691B Cabaret Series Speakers – $300 ea., 4 available

The link is here if you have FB: Log into Facebook

I'm working hard to not buy a pair of the 4628Bs just to check them out.

Paul

Superb woofers, these were only in use for about 20 hours in a prototype design, and are in brand new condition.

$700 for the pair, will ship in the original boxes.

Cheers,

Ken
ken@songeraudio.com

with an amp purchase ? Let me know.

FS: HK Citation II Cage (Reproduction) $79

This is a brand new, high-quality, heavy-duty cage for the Harmon Kardon Citation II Amplifier.

It is professionally painted black. Attaching hardware is not included. The price of steel has tripled in the last year or so, and this unit is sold below cost.

I have a source for the hardware kits -- about $18.00. PM me if interested.

$79 + shipping

I have one channel outputting 18VDC and no idea where to start troubleshooting.
Any help greatly appreciated.

Looking for a finger lift and armrest for a Pickering 194 or 196 tonearm.

So, I've had my VFET amplifier since Thursday and it's now Sunday morning. It has cured my Audiophilia Nervosa (i.e. FOMO) but a worse complaint has set in. I have incurable insomnia! That's right, I've barely slept in days!!

I keep thinking about my music collection, most of which I haven't listened to in 15 years, and wondering how this album or that album will sound. So far I've gone through Michael Franks, Jennifer Warnes, Stanley Jordan, Bill Withers, Thomas Dolby, Ricky Lee Jones, Steely Dan, the Doobie Brothers, Ryuichi Sakamoto and all my test albums. I've started buying CDs again just to hear how they sound.

How can I make it stop?? Argh!!!!

variable DC poewr supply to drive TT motor

Hi all,

I'm looking for a stable lab varible DC power supply to drive a Maxon A-max motor driving my TT.

Found one for sale with:

Ripple & Noise: <1mV rms
Waves and noises: CV<0.5mV r.m.s, CC 3mA, r.m.s
Power effect: CV < 0.01 % +1mV, CC <0.2% + 1mA
Overload effect: CV<0.01% +3mV, CC<0.2% +3mA

could such a supply run my platter good and steady?

Thanks all
Ik

Been an interesting few weeks.
Been trying to sell on a few bits.
1/ Ebay now just a rare sale.
2/ Amazon, listings rarely shown by Amazon so no buyers.
3/ gum tree, no bites.
4/ Ebuy, no sales
5/ DIYAUDIO swap meet, next to nothing sold.

Recession here ?

So after seeing some of the threads on here, and seeing many tubes that would be useful but not finding any sockets, I've designed a PCB based socket for them.

It uses a set of nine Keystone 1434 as the socket pinholes. They are easy to desolder in the event they wear out.

The connections are made to screw terminals.

There is a centre hole to make drilling the chassis easier, too. EDIT: The hole is 3mm. I now know some Novar tubes have the evacuation tip on the bottom. The hole can be drilled out if needed.

To the mods - Move to Vendors if necessary. I post this in parts so people will see it.

Oh, and Happy Wednesday.

Koda

I can detect a 0.5% change in pitch at 1000 Hz...... for instance changing it from 1000 to 1005 Hz.
Who else can dump their comment(s) on here and make it a decent thread?

Hi all,

I am in the process of putting together the parts for my RH84 V.2 EL84SE valve amp.

RH Amplifiers: RH84 amplifier - revision 2

I will be using NOS Russian 6P14P-EV in place of the EL84s.

The suggested rectifier power supply by the designer is a 5R4



The datasheet is here
http://www.r-type.org/pdfs/5r4gy.pdf

I was wondering about using a Russian 5C3S which is being advertised as being equivalent to a 5U4G.



Russian tube 5C3S is a quality equivalent of the 5U4G. Military equipment, high reliability. Svetlana factory. OTK marking.
Name: 5C3S
Type: double-anode rectifier
Application: alternative current rectification
Cathode type: oxide, direct heating
Envelope: glass
Mass: 72g
Filament voltage: 5V
Filament current: 2,7-3,3A
Anode voltage: 75V
Anode current: 0,225A
Socket type: rsh5-1
Max.reverse anode voltage: 1,7kV

The data sheet is here
https://drtube.com/datasheets/5c3s.pdf


The reason is purely down to looks of the tube at this stage. I have tried using the PSD2 software but I am such a novice I am not sure if I have done it correctly.

I have bought Lundahl LL1663 SE OPTs


http://www.lundahl.se/wp-content/uploads/datasheets/1663.pdf

and a Toroidy 10H 250mA toroidal choke for the amp project and will be using 8ohm speakers.

TDS10/250 - Toroidal Choke 10H 250mA DC - Shop Toroidy.pl

I am thinking of using a Hammond 372DX Transformer with
600V CT@144ma, 50 VAC, 5vCT@3A, 6.3VCT@4A which is a bit overkill but would enable PSE in the future I think.

The B+ is 315V

Can anyone advise on the choice of Rectifier tube and any changes to the capacitor values that may be needed to make this work if possible run the PSUD2 software to check the values for me. If it is a no and not worth doing then please do say

If this is in the wrong section could admin move it to the right section?

Thanks for all your help.

Lee

Hi,
i feel like i need to add the 3rd drive into my 2way JBL GTO 609C front doors set. I will custom install it into the A pillar, the tweeter i would probably let them in factory triangle on the door because they would be alligned but would make a custom mold also for better aiming.
The tricky part is what driver would i choose. I don't want to spend very much on these (even tho i know they are crucial drivers regarding clarity).
To keep install ok i would need 3" drivers (4" would be too big)
I have seen real budget speakers from 10USD to 60USD (a bit much for me at the moment).
What brands from the following will i be best with:
Visaton, Lavoce, Dayton Audio, Hivi, Fountek, Monacor, Tang Band and Peerless
From specs, some are even widebands.
They will be amplified (even though i've seen these requiring 15-20 W RMS most)

thanks.

Hi everyone,


This is my first post here, so if I'm doing something wrong, I'm sorry!


I'm repairing an old organ, the previous owner tried to tune it and destroyed what was probably a trimpot (which is now totally missing).
According to the schematics, the part "number" or "name" is "23.515".

I've found pictures of the missing component: Infrequent Sound [sex.tex] technology: GEM Galanti Group Rodeo 49, made in Italy
My missing part is the bottom left potentiometer.

Does this "23.515" refer to something standard ?

Thanks for any advice!

Greetings all,

I have hesitated to which sub-forum to post the topic, but as it is relevant to a low-frequency part of a multi-way speaker, I believe that this sub-forum is the best.

Background

For one reason or another, I had to give away my fully horn-loaded system and live with headphones. I am now in a position to acquire/build a pair of speakers, though not by replicating my former system. I have been contemplating a three-way, preliminarily a MEH above a 15 inch low-frequency driver. I seem to have a preference for a sealed box; which may well be because something always bothered me in a certain frequency portion of ported box. So, I will limit the following drivel to that topology.

Problem definition/proposed standard

From my understanding, one of the criticism of sealed box, and I am paraphrasing, is a “lack of low frequency extension and low efficiency”. Admittedly, this is a rather ill-defined statement, so let me attempt to qualify it vis-à-vis my preferred music genre.

As I tend to listen mostly to classical music, I have found two topics that appear to be relevant: “What high efficiency speaker for Classical Music?”, https://www.diyaudio.com/forums/multi-way/292232-efficiency-speaker-classical-music-26.html, and “A Test. How much Voltage (power) do your speakers need?”, https://www.diyaudio.com/forums/multi-way/204857-test-voltage-power-speakers.html.

I understand that different people may have different opinions regarding the required SPL, still, given the title of at least the first topic, one would expect at least some commonality, but the amplifiers range from a 2A3 to high-power solid state, and associated differences in the amplifier’s power.

In an attempt to understand the power requirement, I propose the following. According to my understanding majority of classical pieces do not have much content below about 40 Hz. Of course, there are exceptions, e.g., P.I. Tchaikovsky - 1812 Overture; R. Strauss - Also sprach Zarathustra; some G. Mahler pieces – 8th symphony, but they are that – exception. Since I live in a quiet environment and my listening preferences are on average 80 dB or less, assuming that the dynamic range of classical music is 20-30 dB it follows that 110 dB at 40 Hz peaks should be the standard.

Method

1. Driver selection

My first naïve idea was to look for high-efficiency 15 inch drivers, but, as I quickly found, they have about the same efficiency, cf., Table 1. So this does not appear to be a silver bullet.

2. Required power vs Vb

Recalling J. A. Hofman’s “iron law”, I decided to investigate the relationship between an enclosure’s Vb and a power that would satisfy the above-proposed standard. I started with Vb=100l, not due to any sophisticated reasoning, but simply because I had built such an enclosure; the idea having been that I had to start somewhere, and by comparing a model for the specific Vb with a measurement, it may be reasonable to correlate to different volumes.

Using Unibox v. 4.08, I had adjusted the power to the required SPL at 40 Hz. I repeated the exercise for different volumes, cf., Table. 2.

Notes: (i) Table 2 summarizes the model without any consideration for a room gain;
(ii) I was not concerned about exceeding the Xmax for the frequencies below the 40 Hz as this is an implementation and not conceptual issue.

Conclusion/Discussion

1. The parameters Fb and even more F3 are not strongly dependent on the change in Vb;
2. There is an inverse relationship between the Vb and the Qts;
3. There is an inverse relationship between the Vb and the power, which agrees with the “iron Law”; and
4. There is no escaping the conclusion that, assuming that the above-defined standard is to be achieved, a power higher than presented in the links is needed.

Provided that the conclusions are correct, and please do not hesitate to point any flaws in my diatribe, the above now presents at least two questions:

1. What would be the best architecture for an amplifier that will be most of the time supplying power 30 dB below peak, considering preliminary frequency of operation 40 Hz – 350 Hz?; and
2. Disregarding WAF, is there any guidance on selecting the Vb, considering the Vb to Qts relationship?

Kindest regards,

M

Table. 1

Driver Fs [Hz] SPL /1W/1M [dB]
TAD1601A 28 97
TD-15M 34.7 97.8
JBL2226 40 97

Table. 2

Vb [l] Fb {Hz] F3 [Hz] Qts Max SPL [dB] Power [W]
101.7 56.1 60.81 0.655 116.30 155
111.9 54.15 60.81 0.632 116.30 145
122.1 52.47 60.26 0.617 116.10 140
132.3 51.01 61.38 0.601 116.00 135
142.4 49.72 60.81 0.585 116.00 130
152.6 48.57 61.94 0.576 115.60 125

Hello all,

I have a Myriad Mi Integrated Amp that has been running well until recently. It hasn't been used for about 9 months and the first time I was listening to it after that it was fine for about 20 minutes and then the amp wend dead, I heard an on-and-off 'buzzing' noise for a few seconds, and then I saw smoke. I pulled the plug and opened it up.

After some investigation it seems that a Varistor (one of two) has blown. In the attached image it is circled in red, it is labelled 'VDR2' on the PCB, the second one is circled in yellow and labelled 'VDR1'.

All other components seem okay to the naked eye.

The two Varistors seem identical. Due to the location of the blown one I can not make out all the markings at the bottom but comparing it to the markings on VDR1 they seem to be identical components (see attached photos). The text that I can clearly read states "ZOV 14D471K (various certification markings) CH52Z".

Some observations that I found interesting were that (a) the two Varistors seem to be identical yet the blown VDR1 is a paler green to the good VDR2, and (b) the failed VDR1 had some heat shrink completely covering it which burned through when it failed.

As I understand it these Varistors are a layer of protection in the circuit to protect from over voltage spikes. Is it logical to assume that this was the cause or could it have just failed independently? If it is likely to have failed due to over voltage would that be coming from the mains supply or a failure upstream in the circuit?

So I have a few questions:

1. Is the colour difference likely due to heat during or leading up to the failure or maybe a different batch, a potential cause of failure?
   
2. Why would there be heat shrink over only one of the Varistors and not the other? Could that have caused overheating and premature failure?
   
3. Can I just replace the failed Varistor with another ZOV 14D471K (of any manufacturer), turn on the Amp, and see what happens?
   
4. Finally, whilst I'm 'in there' is there any point at all replacing and upgrading any of the other components - Cap upgrades for example?

I look forward to your thoughts and advice.

I picked up two hundred 1W 270R carbon composition resistors for a $2 at a ham swap last month. The resistor body is 15mm x 5.8 mm. I was going to keep them as my "lifetime" stock of grid stoppers...

Is there any rule about not using 1 watter's as grid stoppers? They should have no difference than 1/2 watter's in that position no? They certainly have twice the carbon 🙂

I'm kind of prolific when it comes to "making waveguides", but the crazy thing is that 25% of my projects never get posted. Basically I'll make a waveguide in 2-4 hours, print it, measure it, then forget about it for one reason or another.

This is one of those; I don't think I've posted this. If I'm wrong, apologies for the double post.

For some reason both channels of my amplifier thermal protection LEDs are on and the amp does not activate. This happens as soon as I plug in the unit and the power switch in OFF position. When I power on the amp, it does work, but no sound and the transistors are not getting warm at all (both channels). Any help would be appreciated.

Greetings everyone,

I watched this CXC mod video:

[wiki= https://www.youtube.com/watch?v=VoxC3st7WQw]%[/wiki]

And following, relocated the two cables and put a book on top to deal with resonance - these changes made a noticeable difference. I intend now to apply the resonance dampening material inside and will solder in a BNC connector. Near the end of the video, Miguel suggests adding a capacitor to the output, but, no details are given. Has anyone any idea what he’s suggesting, where this cap would be installed and what value?

Any and all information appreciated.

Thanks,

John

Hello everyone !
Here is an updated build or my project :
I want to build a portable "boombox". I must insist on the "portable" as I don't have a car nor a bike. I'm tall and still in "good" shape so I think I can easily move around 15Kg (and If I can't, I'll just use a small trolley, or go to the gym 😀). Usually parties are outdoor, playing for 6hours, for 50-100 people. It won't be the only speaker, it's to support an already existing setup with several boombox (sometimes only one Aiwa Exos-9, which is not enough, that's the main reason why I want to build it). My budget is between 500€ and 750€. I live in France and the wood I can get would cost me around 50€-100€ for MDF (which I entend to use).
I'm not looking for perfection here. The project is basically a cheaper soundboks gen. 3.
Thanks a lot for the help 🙂

Here is the new build :
Mid/bass 10" drivers : Eminence Beta-10A – Thomann France x2
Tweeter compression 1" : Celestion CDX1-1010 – Thomann France
Horn. : Celestion H1-8050 – Thomann France
DSP 2x4: miniDSP Kits: miniDSP 2x4 kit
3way amp : WONDOM AA-AB35281 T-Amp Class D Amplifier Module 3x200W 3 Ohm - Audiophonics
36V battery : https://fra.grandado.com/products/3..._BwE&variant=UHJvZHVjdFZhcmlhbnQ6MjA1MDY4NDg3

Let me know what you think. 🙂

Hi All

I just wanted to share this unit gain headphone amp circuit I designed and built it on Sunday.

So far it has exemplary performance and specs considering its simplicity, the built version exceeded my expectations:
Even thought I show a cap in the circuit, if the JFET's are matched the circuit is DC coupled input to output. I built 2 channels and 1 channel has 4mV DC offset andthe other has an 3.4mV DC output offset
The frequency responce is crazy I measured the responce to be almost perfectly flat with 0dB from 10Hz to 1MHz into a 33R resistor.

The specific JFETs isn't critical as long as IDSS is greater than 3mA and they are matched. I simulated with 2sk170GR, 2sk246GR/BL but I built it with 2sk117Y's (the model of the 2SK117 wasn't good).
The output bias current it set by 0.65/R75+R76, in the built version I went with R75 and R76 5R and R50 10R so it didn't run too hot.

I put it in a box last night and listening to Leonard Cohen with it now.

Have to give credit to Nelson Pass for his constant current stage and Erno Borbely for inspiration.

Cheers

Tim

Well I pulled a 6AV5 out of a box of tubes that was on my bench, but the other end of the tube box didn't have a cover flap. So the 6AV5 slid head first 90 degrees onto a hardwood floor from a height of 3 feet. It shattered. But it shattered perfectly out of its base, meaning there were no shards sticking out of the octal base, smooth all around!

So if you're thinking of smashing an octal tube this is definitely the way to do it. Years a ago I remember hitting one from the side with a tack hammer. All the shards were still sticking out of the base, and I probably smashed up the insides, and plenty of glass remained, not good. This dropping on its head method removes every bit of glass and the insides unharmed.

Hi all. Just letting you know that I've redesigned the RedRoo 5W SE amp to use a powder-coated steel chassis.

I'm also now offering it as a kitset (less the valves and external 12V transformer which many people will already have lying around).

If you want to roll-your-own chassis or use a timber case there is a version with a precision-drilled top plate only.

Or you can download the full design for free from the website, and maybe just purchase the pc board.

Take a look at DIY Valve Amplifier kitset at DIY Valve Amplifier kitset

Phil

Hi all,

I just had a question about the effects loop on a roland JC40. Could any damage be caused by using this as an auxillary input (with my phone)? I've use my phone for a metronome app when I practice through headphones but am afraid to continue doing this out of fear of damaging components of the amp. For clarity, my instrument is plugged into the front input channel, headphones through the headphone jack in the back, and phone plugged into the effects input loop on the back side. Thanks for any input.

C

Hi all,

I am proud to say i've finished a Hugh's project once again. This was a particularly different journey, given i decided to dig up some treasures found in the attic , stored from past ages, but nevertheless one of the most fun to do ever.

I should start to say thanks to Hugh.R.Dean, as this is THE man.
He is behind all this, and of course i am mainly the workforce in a job where the brains is all that matters. Hugh has kindly given my support during this assembly, particularly hard thing to do from the other side of the world about a design thought more than 15 years ago. This is proof of Hugh's commitment to people and to his work. Praises.

So this is my GK-LIFEFORCE.
A tube-hybrid preamp and power amplifier built around a GK-1 and a Lifeforce 100.



I decided to join these 2 products together and mount them in the same chassis, however they are fully independent right down to their AC power input. Built from scratch, i had to source and buy just about every litle part.
It has the same look&feel of my previous designs in the past, right down to Hugh's signature on the front fascia. My tribute to him reamins. Kudos again and again



It features 3x inputs using an ELMA rotary switch and a ALPS 20K volume pot.
There is an independent AC filter conditioning ( FO-FELIX by FOLSOM ) for the GK-1 and the LIFEFORCE.
The Lifeforce was built with its power transistors flip sided so they can directly coupled to the large heatsinks that make up the chassis. This proves to be a very efficient solution, it barely warms up.







Chassis was built with a perforated steel plate separating the AC from DC side (more or less). AC side has filters, transformers and power supply. DC side has the power amp pcbs and the preamp board (split in 2 😀 )





I plan to add little extra in the future. I use a raspberry pi + HAT DAC for source. As this is really small and i still have space inside the chassis close to the inputs i was thinking to built it as a 4th input. Only worried about possible wifi noise going into the tube sensitive preamp. Maybe someone can share experiences ?



Not bad for 6 months work? At least I am happy with it.
All the best
Filipe

This is the followup from:

Schematic hunt: RIAA Phono Preamp

It took me a little over a year to round up all the parts, but mostly just to find some personal bandwidth to dig into this in earnest. I just finished prototyping the tube rectified LCLC power supply found at the bottom here:

RJM Audio - Tube passive phono preamplifier

I followed every component spec to the letter with the only exception being the transformer is 620VCT vs. the specified 625VCT, but the 0.8% variance is almost certainly less than the manufacturing tolerance.

Hammond 372X datasheet:
http://www.hammondmfg.com/pdf/EDB372X.pdf

I fired it up, and checked the output immediately (didn't wait for it to warm up in case I screwed something up). I should see 250-300V from B+ to ground, but I'm actually getting 475VDC!!! Something is very very wrong. Blow up components wrong! Or I'm just an idiot wrong... Very much a possibility here. First rodeo of this sort.

My Fluke is only good for 600V AC/DC, so I can't test for the 620V output of the transformer secondary coil, but I can test from each of the 310V sides of the 620VCT output coil to 0V, and they're giving me 348V. That's ~11% high, and probably within manufacturing tolerance*. My mains current is 123V as of just now (I used the 120V blu/brn and wht/blk leads for the primary coils).

What could I have messed up and how to get such a high output voltage from this power supply?

*Looking closer at the transformer datasheet, I see that the wiring setup for what's supposed to be 620VCT is actually expected to output 340.0V +/-2% with 120V, which is very close to the 348V I got, but not at all the 310V printed elsewhere on the same datasheet/half the 620V that's on the sticker on the physical component...?

Hi all

I have recently acquired Nelson Pass' M2 kit, and as such I have decided to build a proper power supply to compliment it.

A friend of mine gave me an MCI 4-05-5602 transformer. The only problem is that I cannot find its datasheet, let alone any evidence of its existence.

Here are some pictures of the actual transformer...
Imgur: The magic of the Internet

If anyone could help me find its datasheet or provide any info on it I would appreciate it a lot!

I'm intrigued by what I believe is called terminated transmission line...I mean a transmission line inside a sealed enclosure, to be used for the midbass within an active 4-way system.

A couple of sealed subwoofers take care below 80hz. The midabass would cover 80 to 450Hz or so, in a sealed enclosure. Midrange and tweeter would be in sealed boxes too, I think.

Is the midbass a good range for TL? I understand the back wave of the driver bounces back against the back of the cabinet (assuming a flat, vertical surface) and out through the cone itself, out of phase. This generates distortion and is most prominent at frequencies where 1/4 of the wavelength equates the depth of the cabinet. At 80Hz the 1/4 wave is 108cm long, at 150Hz it's 57cm, and at 300Hz it's 29cm. So in my mind midbass is where TL ought to be applied. Am I right?

Are the gains worth the trouble of building this? Maybe I'm conceptually correct but this is not material enough?

Alternatively I could build a quadratic residue diffuser against the back wall to break down the back wave, or even simply place a very large chamfered piece to scatter it.

FWIW, some midbass woofer alternatives under consideration are twin Beyma 10G40 per side (each in its own enclosure), or one 12P80Fe or Nd per side.

Looking forward to your input!

Can I safely replace 2SD218 with MJ15003? These are the only parts that are original manufacturer that I can obtain new where I live.
Amplifier is AA-8500. I will replace all 8 in both channels.

Was this tube primarily intended to replace the 6L6 for use in more compact cabinets? I see that fans of each tube exist. Do I remember seeing a compact 6L6 also? Thanks.

I recently picked up an Onkyo A-8800 from someone who said the "digital filters" were broken. I thought he meant there was something up in the DAC board but it turns out the real issue is when the selector dial is turned from "direct" to "tone" the left speaker channel cuts out except for very high frequencies, and when turned to "tone + processor" both channels get very distorted. I'm decent with electronics but have never taken apart an amplifier before -- where should I start?

Started on a new project for a capacitor ESR tester.
A ac waveform is applied to the cap under test.
The output is monitored and measured by an a2d converter.
This is USB'ed to the PC and the pc prints out ESR ohms.
A sledgehammer to crack a nut maybe.
The output of cap is peak detected and smoothed into a buffer then a2d.

I'm thinking specifically of how the BA-3 front end can also be used as the core of a preamp. Is this usually the case, at least in principle if not practicality? More generally, would it be beneficial to remove this double gain and make either the preamp or power amp input passive, to reduce the total number of gain stages?

Hello

Is it possible to repair a cracked vacuum fluorescent display that has been exposed to oxygen? Are there gases that were lost? I was thinking of reheating the seal point and closing the hole. Or is it too late?

Paul

Hey folks, I have a Fosi Audio class D amp that's been on my PC desktop for a while. It's useful and wasn't outrageously expensive.

I have two gripes about this little feller, and I'm interested in seeing if I can tinker with it to smooth things over. Not a value proposition or whatever - I have it and I like to tinker so that's what I'm doing.

Problem 1: volume pot tracks unevenly between channels. Not a huge problem, I'll replace the pot.

Problem 2: Upon power-up there's always static on the volume pot. If I wiggle it around a little bit, it'll make staticky crunchy noises and channels will drop out intermittently. Then they get quieter as I move the knob until eventually the attenuator works quietly with no dropouts. Question: does this mean there's DC on the pot? What would cause this sort of noise?

It's a new sealed pot so I doubt dirt / grime in the contacts is the issue.

What do you think?

Go to this thread.

http://www.audioheritage.org/vbulletin/showpost.php?p=61627&postcount=318

I don't work for Passlabs (yet) but I will always support and believe in a product that sells itself.

The people behind the product are of course what makes it a star.

Macka

Not much info on these so thought a quick 1st impressions might be useful. I have powered my 'Unibuff' with a 30va Toroid @15v through a generic rectifier/regulator using decent parts like nichicon 3x1000uf smoothing caps and schotty diodes. I don't really like the screw clamp connectors and have direct soldered to the bottom of the board. I'm running balanced in via 20K 4 gang pot and using balanced out for main and SE to subwoofer. (both work simultaneously).

The noise floor is inaudible.

There is little or no effect on timbre vs running passive.
I do think I detect a smoother treble, and also a better control of sibilance - though suspect this is down to improved matching through my system rather than unibuf 'adding' anything. (Was Running Ares direct to NC400).

Dynamics are not much different (do i detect some extra punch?), and do I detect some soundstage refinement in depth, and location? - I think so, the take-away being no detriment here imo. Another finding has mooted running the unibuf with some gain (I am currently 1;1) has given livelier dynamics. (just add resistors in pre drilled locations)

Overall; I find this is indeed a 'transparent' circuit, and an easy route to creating a quality (and silent!) preamp.

Replaced one channel of the AB outputs and got all 4 AB output boards running.

Amp remains in mute. There is no gate voltage to any of the 4 Jfet muting transistors - not sure yet where the muting is for the Class D sub channel.

If I remove jfet channel operates normally.

All voltages are correct on all 5 channels.

Trying to trace out where muting originates. Maybe on the preamp board close to the remote power on section?

Anyone have any knowledge of what/where the muting circuits are?

Hi, are there people here who know something about limiters and equal loudness contour circuits on adau1701. I use a dspb250 board from dayton with adau1701 and want to get the best out the project but i don't know where to start because it's a bit overwelming for a beginner. Who have some knowlegde about it??

I've looked through a number of the help threads on attaching images but haven't found an answer to this.

When people build illustrated DIY guides and such, what's the best way to embed images inline such that they're viewable by everyone regardless whether they're logged in or not? When I look at many of the existing threads they are viewable to the public but it seems if you upload the image file to be hosted by the DIYAudio forum, its only available to those who are logged into the forum.

Does the image need to be hosted externally and linked. Is there a permissions thing that can be changed in the DIYAudio uploads?

Ideas? Thanks!

hai,
i use Allo usbridge signature with picore player and bubble upnp[android mobile] to stream tidal quobuz and spotify[LMS plugin]. I would like to stream apple music too via the same setup.
Is is possible ? Kindly help

Hello All,

Just had the lid off and take a fancy at replacing the caps:

4x 0.47u 275v
2x 0.22u 275v

Would like to replace them with ClarityCap ESAs, but they don't seem to make any to the same exact spec. Their 0.22u's are 630v and the 0.47u's are available in 250v and 630v.

Does this matter if they are not an exact match on the voltage ?

Many thanks

Aikido octal 6sn7 completed and used for about two years. All original boards with verry good parts and PS-21 Psu. It is build in some old rotel preamp enclosure, is not the best enclosure but not the worst either. The buyer will become 4 pieces tungsol Nos mouse ear tubes plus one spair, 4 tungsol reissue tubes used for about 100 hours and a pair of Nos Hytron 6sn7gt tubes never used. Price is 1750 euro including all tubes and shipping inside EU only. For more info or price offer, contact me. Payment thru paypal or bank transfer.