Greetings,

A few months ago I had something dreadful happen in my life and it has caused a steep decline into unhealthy obsession. What occured was this video, showing up in my recommended feed. Oh boy, the spiral.
Then he goes ahead and releases another video and things only get worse.

So naturally... I decide to start building my own DML Speakers, which the first iteration looked a little like this:



But that wasn't good enough, they were rediculously large and the build quality was really only to a prototype/proof of concept level. I needed something better. Not only that, I hated the design of the passive crossover network, it was as if as soon as I introduced it the life was sucked from the panels and it's spine tingling sound dissapeared.
Alas, I chose to keep the network for the time being, add a tweeter section, and carry forward with the reconstruction.

As it stands, the full project is yet to be completed, though I'm not far off I don't think.
DML Speakers: Fully operational, just a couple items left until completion
6 Channel Amplifier: Linear Supply prototype tested and amp boards assembled.
Linkwitz Reily 24db/oct 3 way stereo crossover: Constructed, needs rewiring and testing.
Preamp: CNC phono preamp & Mussify 15-0-15 supply pre-existing, k5169 Preamp Kit needs assembly, and Case needs building too. So just the pieces :/

Alrighty, picture time:

DML Construction
Drivers are da175-8, DAEX32EP-4, and PTMini-6.
Turns out these look like big IPhones, oh well, Steve Jobs would be proud.

Passive Crossover v1

Passive Crossover v2














Current Evolution:


Active Crossover:
Used VituixCAD to model the passive network, as well as the crossover points for this board. Sellers on Aliexpress provide these with custom ranges, they change the cap and r values around to meet the need. Construction quality seems high, but what would I know (shrug?).








Preamp:
Just Image these two doods together inside a case that looks like the crossovers 😛



Power Amp:
Same deal with the preamp, just imagine them in a simlar case as the crossover 😛




I have no experience building speakers or hi fi gear, but I've always been the type to void warranties out of morbid curiousity. So it seems I know enough about electronics to be dangerous, hence I invite discussion, recommendation and critique. Hopefully I can find new ways to improve upon the design.
I haven't taken many photos or made great descriptions so if you've got questions, I'll answer em.

I'll keep updating with progress.

I bought the Boyuu A9 el34 tube amp from China. It will not play as loud as my cell phone. I replaced all tubes and that did not fix the problem. I think he may have sent me a 220 volt instead of 110 volt. Argued with him for 2 months and finally gave up. Any help or a point in the right direction would be greatly appreciated. Cannot send it back.

Hello,

I am looking to have a 12V trigger input. I am trying to find info online about a 12V trigger specification but it seems that different manufacturers do different things.

Anyway, my question is:
Is 12V trigger typically 12V for on and open circuit (high impedance) for off
or
12V on and 0V (driven to 0V) for off?

Thanks;
Leo

Follow this excellent audio amplifier, designed by me based on the original layout so good and reputable Douglas Self.

The main changes and additions were based towards greater power, higher working voltage, adjustable gain, bootstrap option on and off, using more current components and some minor changes of values ​​in order to work well with these changes.

Have a great gain, I suggest using a well-designed and well filtered power supply, especially if it is with common transformer.

follows:









Sorry, the images below are the guidelines in the Portuguese language, because they drew up especially for nosos national forum, but i guess you can understand:




IMPORTANT FACT ABOUT BIAS ADJUSTMENT:

BIAS ADJUSTMENT MUST BE PERFORMED AFTER THE CHOICE OF MODE OF OPERATION (BOOTSTRAP ON OR OFF), AND MUST BE redone AGAIN IF THE CHOICE OF OPERATION MODE IS CHANGED.







Below is a shield against the DC outputs, I used automotive relays because they are cheaper and bearing a larger chain:



Below is a rectifier plate with soft start built for those who want to make with conventional transformer. This system couples the capacitors until they've been previously loaded via load resistors:





Below are links to download the respective PCBs PFDs...

Complete amp:

https://mega.co.nz/#!mRZV0KhI!N2cQnUwLUK3nGqLudaFRfA5DaSBpAIVWrVvrBD6AFwY

Protector DC:

https://mega.co.nz/#!zUowlSCA!CZehRxETRFc7XJ4oCsXj1Q8n8CJXhmGjAx49uyZB6_I

Rectifying with softstart:

https://mega.co.nz/#!uZogmJaA!Aydvjy1sJKOIjma4PUscv1evev0DkARO0OCG1RQRRc0

Follows a video that demonstrates the immense sound quality of this amp here. I beg you not notice the mess on my desk, the power supply is improvised and inadequate:

Teste de médios / Agudos (Cindy Lauper) - Debunker - YouTube

Friends, please excuse my horrible English. Any questions, we are here ...

Hello mods
I am trying to reply to a private message but after I click on send, my reply text disappears. I dont know therefore if it was sent or not.

Any ideas?

Thanks

Tapping ballanced XLR to RCA?

Is it possible to make a tap on balanced XLR cable to another RCA output but still retain the balanced "noise free" on the XLR line?
I've got one balanced XLR output to amp on my mixer but also need to run it to another amp with RCA connectors.

Selling my Mark Johnson "Noir" Class A amp.
Smooth ALPs Blue Velvet volume control.
Works well with HI/Low impedance cans.

Price to build approx $200. Will sell for $200.
Split shipping cost so add $10 to price.

You can read my review here:
Mark Johnson Noir Class A Amp (aka T2) - Do It Yourself (DIY & Mods) - The HEADPHONE Community

Build Thread:
https://www.diyaudio.com/forums/hea...or-headphone-amp-class-single-150ma-bias.html

The Noir is on the bottom of this stack:

I noticed a hum and pulsing noise coming from my DAC even though it wasn’t on. I speculated it could be DC on the AC line. I tracked it down to a heating pad on the circuit. While I have no idea how accurate my testing was, I measured 10 millivolts with the heating pad off and 200 millivolts with it turned on. With it off the hum and pulsing stopped. That’s great because there’s nothing wrong with my DAC. Can anyone tell me definitively whether I’m somehow damaging the transformer when I use the heating pad? Would this cause a degradation in sound when the DAC is in use? Is there a relatively easy was to remove any DC on the AC line? Thanks for any answers you provide.

Ironamp project video posted here:

https://www.youtube.com/watch?v=FZymAeaVsAg

I hope you enjoy it. 🙂

I updated the captions if you want to try Youtube's translation option - should be funny 🙂

Hi Guys

I'm selling 4 pieces of Hovland Musicap 0,1µF/400V capacitors. 60€ including shipping.

Regards

I have 2 red tops crossed swords and 2 blue top .
I bought these from a reputable high end Hifi and tube dealer in Holland ( receipt provided)
I am assured by him and other tube aficionados that these are genuine.
I paid €200 euros for the 2 pairs so I’m asking £200.

For Sale one LME49720HA MM Phonostage and two Salas Shunt power supply (negative and positive).

The phono stage is based on the project from LME49720 datasheet. High quality components (Nichicon for audio, WIMA, ELNA low ESR etc.)

What you see in the picture is what you get.

The price is 135 Euro + Shipping to EU only.

Hello I have a Audio Note Kits (ANK) Canada Dac 4.1 with tube output stage with two 5687 tubes.
For tube rolling I bought this socket from eBay
"1PC Convert Tube Socket 12BH7 (Top) TO 5687 (Bottom) Tube DIY Adapter Socket"
1PC Convert Tube Socket 12BH7 (Top) TO 5687 (Bottom) Tube DIY Adapter Socket | eBay

After using this socket with 12BH7a tubes instead of 5687 and starting the DAC big distortion in sound started with very little audio signal. The tubes got very hot. I immediately switched of the DAC.
After I removed the adapters and just used my original 5687. Still the same distortion and my tubes got very hot.

Did I destroy the DAC?
Can anyone of tube experts help please?
The Tube output is connected for I think 12volts heater supply to 5687.
So what I need to repair? Is main power transformer burned or I have to change some capacitor?
Thanking you in advance😕

Hi
i have a raspberry pi 4 and Khadas tone board
i want to power the pi via the original power supply but i would like to give the tone board a low noise supply to improve the sound .
what i want to know is if i split the power from the supply and feed it into a buck converter board set at 5v to 7v out to feed the tps7a4700 ultra low noise regulator board set at 5v to power the tone board ? would this be ok ? see pic
the buck is there to give the regulator a bit of voltage to drop
CamScanner 05-22-2020 22.06.23_1 by glenn jarrett, on Flickr

These are 7 pin tubes, do they fit into 9 pin sockets?

Hi,

I'm building an amp that will use a Hypex SMPS1200A400 power supply (DIYclassd.com), and I want to add a soft start module, also from Hypex (DIYclassd.com) for in-rush current protection as well as standby functionality.

The soft-start module will make it relatively straight-forward to add a push-button to toggle the amp between standby and on. I would also like to add a 12V trigger, but Hypex told me that their soft-start module doesn't support that feature.

Does anyone here know of a way to rig something up so a 12V trigger could still work with this soft-start module? I'd prefer to use this module as with it the power supply would only draw 1.2W in standby mode, whereas without it, it will draw 9W in standby mode.

And otherwise, is a soft-start module really necessary? I'm pretty new to working with electronics and would like to be able to put this amp in standby mode or switch it on with a button on the front of my case, and use the 12V trigger to turn it on/standby from other components in my system.

Would appreciate any ideas 🙂

What would be a good supply to power the 3.3v this diyinhk xmos board requires ?
XMOS 384kHz DXD DSD256 high-quality USB to I2S/DSD/SPDIF PCB - DIYINHK

I'm currently using one of these
low noise Pre-Amp / DAC power supply MJE15034 TL072 Regulator based on STUDER 900
to power a SRC at 5v and another at 6v feeding an AMS1117 board to power the xmos.
5pcs DC 5V to 3.3V Step-Down Power Supply Module AMS1117-3.3 800MA LDO NEW 700850568148 | eBay

What would improve on that ?

Hi everyone, I've been a music and hi-fi fan for over forty years. A sound engineer friend recently introduced me to the wonderful world of DIY performance upgrades and I have been cheerfully tinkering with many old CD players and amplifiers, giving them a new lease of life.

For me it's been about bringing equipment back so someone else can enjoy it and also funding the upgrades on my lounge system! I've just completed a full restoration on a Sansui SR222 MkII, including building a brand new plinth and base from MDF. A trip down memory lane as one of these beauties was my first piece of real hi-fi. A saga for another day perhaps.

Anyway, I look forward to hearing all about your adventures in this wonderful hobby and learning how to do more than just recap amps and fix broken CD mechs!

Take care everyone.

Mark

This is one speaker that I have not seen cloned (or facsimiled)

Spica TC-50 (woofers 8 ohm data)
Spica TC-50 Product Information, The Spica Speaker Enthustiast


Crossover
Spica TC-50 Crossover, The Spica Speaker Enthustiast

Speaker Replacements: Madisound Speaker Components

"Spica Speaker Replacements
Spica TC50

The Audax tweeters used in this speaker are available again! The new tweeter is the Audax TW025A2 tweeter, replacing the old part number of HD100D25. The woofer is the Hif 17JVX 4 ohm and we don't know of any similar speaker to replace this driver. There is no fix for the woofer that we are aware of. Bad woofer = junk speaker."



I think this is close to the Audax.

Visaton W170s (vas? difference)

Visaton W170S-8 6.5" Woofer with Treated Paper Cone 8 Ohm

Visaton W170S-4 6.5" Woofer with Treated Paper Cone 4 Ohm


Aside from an exact replacement woofer, what are the important parameters for a substitute?

TIA
-Chris

Hi,

Please look at the schematic.
This is presented as a clone of REDDI DI box in a different forum.
The pot at the output will short the transformer at the extreme position.
Am I missing anything here?
Thank you
Glass painter

I've recently started designing PCBs in Kicad and would like to know of any people or companies who make circuit boards that you'd consider exceptional examples or even interesting examples of design styles. I'm spending plenty of time reading about design methodology and I'd like to supplement that by looking at a variety of implementations.

Luxman emphasize their circuit boards and their maybeslightlygimmicky curvy lines, Audio Research has a sort of stylistic signature, Audio Note UK certainly does, Lavardin does some pretty patterned ground planes, Aavik likes planar inductors, and there are many examples of creative component and case mounting.

Whose boards do you consider exemplary?

I have been looking at some of the measurements Amir has been performing over at audiosciencereview.com with a Klippel Near Field Scanner

There was one for the JBL LSR 305P MKii speakers and I happen to have a pair so I downloaded the measurements to have a look. After a bit of fiddling I got the On Axis and Listening Window responses into REW. They are very similar with a little bit of a rise in high frequencies for the on axis response.



A couple of people had made EQ corrections for them over at ASR so I thought I would try my hand at it.

I used manual EQ to flatten the curve as much as I could without micro managing it too much, the result was much flatter.



There were still a few minor bumps that would be difficult to try and improve on with basic PEQ so I started on an inversion based EQ.

I used REW to invert the Listening Window response using 1/A in Trace Arithmetic. This isn't very usable as it is with the huge boost to flatten the low rolloff.



There is a way to use DRC_FIR to apply a target response to a dirac pulse so you end up with an impulse from a text file. I exported the measurement as text and only used the portion between 67Hz and 4K to avoid the excess boost and not correct above 4K as apparently the measurement is not valid over that point due to an error in the operation of the Klippel, this speaker was the first test measurement.



A couple of edits to the text file to make it work with DRC and this is the filter that came out. It corrects the measurement to flat between 67Hz and 4K very nicely.



Here is a comparison of the basic REW PEQ and the DRC filter. My manual filter is very similar to the inversion so I'm happy I did a good job there.



I have attached an MDAT (LSR Klippel EQ.zip) of the different steps in case anybody wants to look. By selecting the Listening Window response and the EQ tab the REW EQ settings can be exported if anyone wants to give it a try.

I have also attached the impulse correction filter as a zipped wav (LSR.zip) for use in a convolver. There is a slight gain of about 2dB add a reduction if you need to.

I haven't tested this myself to see if it works as I don't have the speakers set up at the moment. I will test it out at some point and report back.

Hello!

I need some help regarding the repair of vintage amplifier. When I replace the output transistors 2n3055 or MJE 3055, they burn out. Also, what is a good replacement for the driver transistors?(schematic down below)

Best Regards electronicsman

HSR 48 shema - Google Search

I have one of the later (TOG) Cyrus Ones.
It has been “upgraded” before I got it, back in 2008 or so.
However whilst we’re all under lockdown, and as the front panel badly needed repainting anyway, I decided it could do with a look over, including having a proper look at the electrolytics. The onboard polarised caps were all Panasonic FCs and looked in good order, so I left them alone.
The original PSU caps (which I believe were rather nice slit foils) had been replaced at some point by Nippon Chem Con KMG ones. Since Cyrus spec’d slit foils, I decided to return it to spec.
The original NP electrolytics had also been replaced before I got it, by ones from SJE (Sang Jing Electronics).
I decided to replace the main PSU caps (with 10,000uf slit foils from DNM) and replace the NP electrolytics (with a mix of Nichicon Muse and Elna from HiFiCollective). I did think of replacing the lower value NP caps with Poly caps, but I would have been tight for space on the board, so stuck with NCs.
Results are spectacularly good. I’m delighted and would thoroughly recommend these components to anyone looking to keep their old Cyrus One running.
Paul

Hi, yesterday i found a couple of speaker in my storage room. It doesn't have any specs written on its box other than W3-2001S. I have attached some pictures of the driver. It measures at 3 inch. Do anyone know who manufactures this speakers an or know the specs? Any help would be appreciated. Thanks!

Please help me close this thread: chipAMP with flat TF beyond 50KHz with any inductive speaker?

...and also let me know how to do such requests-to-admin more simple, if any possibility exist. Please advise.

Thanks,
Ionmw

Only two ports , input and output , base on a switch IC

What I mean is, how important it is to match (hfe) output transistors on a class A/B power amplifier, if they have emitter resistors.

Attaching the area around TL494. One side drivers burn and burnt the board too. It is soundstream tx2.1500 amp. I cleaned the area and changed TL494 removed all the power fets from board. Switched on the amp to see oscillations. Found no oscillations. Pin 16 is high 3.5v . It is connected to optocoupler and pin3 through diode. I removed the diode and optocoupler still getting 3v on pin16. And pin 3 is 3.5v. Getting oscillations but duty cycle is far different from normal oscillations.

Hi all ,

I am restoring a PIONEER SA – 810 tube amplifier for a
friend of mine , but I don’t have the schematics , I could
not find anything in Google or Yahoo .

Please , can anybody help me ??? As the service is for
my friend ( and FREE .... !!!! ) , I can’t spend money , so
I need your help guys . Any file format will be wellcome !!!

Hi gingertube ,

I was reading an old thread ( 11-03-2005 ) , where you
had said that you have a CD with all Pioneer tube schema-
tics , in .pcx Photoshop format file , and the SA-810 schema-
tics was there . Do you still have this CD ??? Can you help
me ??? It’s not possible to make contact with your e-mail
through the forum , because it is not available . If you read
it , please reply !!!

Any input will be wellcome . Thanks in advance for all .

Carlos

Hi,

I have recently studied the principles of some well known commercial power supplies, such as the Paul Hynes SR-7, Uptone JS2, etc... , and it appears that the quality of the transformer has an impact on the final result (sound quality).

As I am not an expert in the transformers domain, I try to identify what are the criterias that make a transformer better (sounding) than another. I know a firm that can manufacture custom transformers, Toroidals and C-core.
Of course the Transformer is not the only part to make a difference, but for now I just focus on the transformer.

The cost is not really a concern for the time being: I just try to identify the criteria to care about.

The P.S. should be able to deliver 10A on 12V, with 2 rails.

So:
-Toroids or C-Core ?
-And of course what are the other things that could be asked to the manufacturer ? screen, what quality of materials, etc...

Thank you for your replies

Recently I had a couple of stylii send off to be imaged as a favour. Both AT microlines, but one well worn (audibly so) and the other under 10 hours. After sticking them under the microscope a track was recorded with each so there is a record of what a worn out stylus sounds like. But we were mulling what sort of audio analysis might be useful. If I can work out how to operate dropbox I'll post links here but in the meantime any ideas what might be of use?

Hi
I ordered some speaker ports for a smallish desktop design, however on receiving the ports I’ve found the actually taper from approx 41mm at the front to 38 at the rear over about a 100mm length.
So the question is which measurement do I base the calculations off the opening @ 41mm or the rear of the port @38mm or do I take an average between the two?
Thanks for any inout

Hi,

with standard UL configuration, where screens are connected to the same voltage supply of the plates, the higher the signal at the input, the lower the plates go compared to the screens (more secondary emission?) but in any case screens will never go negative.

With tertiary windings, like for 6550 where to maximize power you need to connect plates to 600V and screens to 300V, or GU50 with plates at 900V and screens at 300V.

Now if you have classic 43% UL connection, and the plates swing down to 50V, the screens will swing:
- 6550: (600-50) x 0,43 = 236,5 Vp
- GU50: (900-50) x 0,43 = 365,5 Vp

So when the plates will be at 50V the screens will go down to:
- 6550: 300 - 236,5 = 63,5 V (still positive and close to Va)
- GU50: 300 - 365,5 = -65,6 V (negative voltage)

So the first case is ok, there will be almost no secondary emission I would say, and screens should have no issue, but what happens on GU50s with negative voltage on screens?

LTSpice simulations go into oscillation, but what will happen in reality?

Thanks

I have a pair of 10" subwoofers, on an engineered hardwood floor, over slab-on-grade concrete. Currently I have them sitting on Auralex MoPad foam isolators. I have threaded spikes in a drawer.

I am not keen to use the spikes because in the past they have damaged wooden floors, even when mounted in cups. Also, installing them is a pain in the ***.

What does theory say I should use, isolators or spikes? What is your personal experience?

Is it any good
#Aliexpress US $63.19 21%OFF | Nobsound Mini FU32(832A) Valve Tube Amplifier Hi-Fi Stereo Preamp Desktop Tube Headphone Amp
Nobsound Mini FU32(832A) Valve Tube Amplifier Hi Fi Stereo Preamp Desktop Tube Headphone Amp|Amplifier| - AliExpress

I don't have a specific purpose. I just think it look Uber cool. Could it be used as a buffer for pascal spro2 module. Or only as headphone preamp? I also have have a Kt120 class A amp that also need some fun stuff

Anyone have a copy of this service manual? Pacparts doesn't sell them. :/ (Likely due to the recall.)

I have a decommissioned (recalled) unit that I'd like to be able pull some parts from for testing another amp. The parts list from the service manual would make identifying parts much easier.

It's a long shot but does anyone have a wiring diagram for a denco TDO 2 tape recorder oscillating coil ?
Thankyou colin

I thought it would be fun to have a new project during the current covid-19 work from home situation so I picked up a pair of "custom" speakers cheap that were made from Rectilinear III Highboys. After doing a little research about speaker design I realized I was in way over my head.

I've got tools and I'm handy with wood and steel but know very little about speaker design or audio wiring in general.

So what here is what I am starting with:



Yes, those are the original tweeters and super tweeters covered over with silicon caulk. I know, the horror. I have enough OCD that it wouldn't let me leave these as is even if they sounded perfect.

One speaker sounded OK (not great, but OK) and the other one was was flat like when the caps have gone bad in the crossover. I took them apart annd this is what I am left with:



Box outside dimensions 31 7/8"H x 17 7/8"W x 12"D (baffle is recessed 7/8")
Made from 3/4" panels. There is a 3" foot on both speakers.

The baffle is easy to remove and I plan on replacing it with the new configuration.

I calculate the volume at 2.77 cubic ft (78.5 Liters) before subtracting volume of bracing etc.

The salvageable components I pulled are:
Dayton Audio DC300-8 12" woofer 8 Ohm with
Peerless 821639 2" Poly Dome Midrange 4 Ohm
JAMO 20134 1" Soft Dome Tweeter 8 Ohm
all tested and working.

So my first question is are any of the drivers worth re-using? I'd like to at least re-use the woofers in the new design as long as they are not dogs.

Thanks.

Hi,

I have a Berhinger ADA8000 that the mains transformer has burned out. Anybody knows where I can get a replacement? I read some threads and seems that it's a common problem with these units.

Thanks.

I have an Xtant 3300c in my Camry, and I never bothered to get it set up right. I always had to turn up the volume on my deck too far to get the volume I wanted out of the amp, and my speakers are of reasonable efficiency. Because of that, I'd like to see if adjusting gain settings will help.


The gain jumper for the two front channels is set to the 0 setting. I'm not clear from the installation manual what that means. What is the gain for this model amp when the gain is set to 0?


Also, what's the difference between that gain jumper and the rotary gain pots for the front channel?


Can you folks recommend a procedure for setting gain properly on this amp, both jumper and rotary pot controls?


Thanks

Does anyone make a plate amp for powered speakers that has both wifi capability AND an active crossover?

Dayton Audio WF60PA has the wireless. Hypex FusionAmp FA122 has the active crossover. Any product have both?

TIA.

I've run a few searches and can only find one reference of the LM3886SMPS board.

LM3886SMPS | Connex Electronic

LM3886SMPS Stereo Amplifier Module 2x 60W 4 Ohms LM3886T - Audiophonics

All I can find is a picture of a partially installed board:

http://www.jkwynn.co.uk/Pics/LM3886_Lashup.JPG

I am in the process of finishing a set of Alpair 7.3s for my desk set-up and am currently running a 2xTPA3118d2 amp with a 19v 6a power supply.

I was about to pull the trigger on an ICEpower 50ASX2SE and a case from Ghent Audio until I came across the LM3886SMPS. From my understanding, both amplifiers are easy to assemble, the only major difference being that the LM3886 requires a heat sink.


Could anyone offer any advice on which board to purchase, I would greatly appreciate the feedback.

So, I found a power amp, specifically this one:
STK4133II WITH BOARD - Integrated Circuit - KSP ELECTRONICS
(Yes, with the board)
I searched the web but didn't found any datasheet that explaines what are those 18 pins do or even better, where shall i connect the 9 coloured cables of this board.


Does anyone have any clue?

Anyone know the value of these resistors ?

They are all discolored and are way out of tolorance .

And know why they may have burned ?

Hello!

I have a Heathkit AR-15 receiver. I recently began having this problem: The volume control does not reduce the volume to zero, on one side only. The right side.
This started after I had the control way up high, because of a Passive Volume Control I inserted after the “Tape Monitor” output and the “Tape Monitor” input. I was using an external volume control to control volume, so the actual volume control on the receiver was turned way up – to the maximum level I figured I’d ever need it. Long story – with a passive volume control I was able to control other devices that were being fed by the Tape Monitor output as well as the receiver itself.
I can’t imagine why that would cause the problem I’m having but it seems like it did. I don’t enough to zero in on what happened when I skewed the volume in that way. I’m stuck at the cause-and-effect level, without the knowledge to go any further.
So the actual problem is, that while the volume in the left channel is reduced to zero by the control, the volume in the right channel hits a plateau and will not go below that. Not even the “balance” control can reduce it.
(NOTE: the Passive Volume Control has been removed and the only volume control being used now, and described here, is the one proper to the AR-15.)
After maybe 20 seconds or so, there is a “null” spot in the rotation of the volume control potentiometer where the volume in the right channel – as well as the volume in the left channel - is almost zero. But that spot is not where the potentiometer is at the zero spot; it’s a little bit after. In other words, at a place where some minimal volume would be expected.
I was willing to let it go at that, since I’d never really need the volume to be that low. So if the receiver powered up at that volume level it wouldn’t be a problem.
The control starts to work as it should at that point and from there on up.
(to re-cap: below a certain point in the Volume Control potentiometer’s trajectory, the right channel sticks at a certain volume and there’s no way to cut it out. Even the balance control has no effect on it. Above that point the volume goes up and down as it should, following the volume control.
BUT if I set the volume control at the above-mentioned “null” spot where both channels are almost zero, and then turn the unit off and back on again, the right channel comes on quite loud. After a short time, well under a minute, the volume begins to drop – back to the almost-zero spot again.
I thought it was the volume control itself so I replaced it. To my dismay, the problem is still there.
In my naïve way of seeing things, I have isolated the 10mfd capacitor that comes after the volume control and before the final two amplifying transistors in the pre-amp and/or the 10 mfd capacitor that intervenes between the pre-amp and the amplifier as possible culprits. My reasoning is that, since capacitors charge, one of those two, or both, capacitors might restrict the volume while charged but, after the unit is turned off it (or they) would discharge and no longer restrict the volume.
I don’t know if this theory has any validity. What I don’t know is how or why a capacitor would be used to restrict volume. So I’m in need of a more knowledgeable opinion. There may well be some other culprit in the current problem, and I am curious to know what it is.
Can someone help me out? I’ve drawn circles around the volume control and the two capacitors I mentioned on the first attached file. The second one is the entire schematic for the AR-15.
Well, that was my plan anyway. Maybe you can help me figure out why this website wouldn't upload my files. I guess th



I’d appreciate someone’s more knowledgeable analysis. Thanks in advance!

bob

Cambridge CD2 manuals, schematics & mods

Does anyone have any information on the Cambridge CD2 manuals, schematics and modifications.

I intend to fit the Elso Kwak clock.
Also a common problem with the cd2 is with the display switching left to right.

just wondering if a pair of 2sa1492/2sc3856 would be a suitable replacement for the original 2sa1294/2sc3263 power transistors in a silver face fender frontman 212r?

I was in the process of redoing my boxes. And i noticed about 3 of my mids, have very small dents/scratches. Pictures below can be seen.

I was just wondering if this will be audible?

And how can I test the impact of them to see if they are still working as intended to?

I was thinking of measuring all the mids against the one that I know is in perfect form. Should I do it 1" away like with subwoofers? Or should I do it 1 meter?

Title says it all. Too much time for cooking and eating and not a whole lot of ladder climbing. Not allowed to play tennis unless it's with someone in your household. Many of the parks are closed, including some dog parks. Very little recreational activities of the interesting kind these days.

It's all eat, drink and be lazy and it's showing up just above my belt.

Hey all, new to the forum, great info here, even if you're a novice (me).

But, I am a discriminating listener, had done some research here and elsewhere and felt confident that buying a smsl sa-36a pro would be a good choice - with all the high marks given to the tpa3116/3118 chips.

When I received it, the back voltage markings were suspicious (12-15v instead of 12-24v), so I opened it up and here's what I saw: not a tpa3116/3118 but instead a TDA7492PE chip! And seams to be under-powered. I've ordered 3 now from 3 different sellers: Amazon ships and sold by, CrazyEve/Amazon, and an ebay seller sourced in China that seemed legit and shipped very fast (US warehouse probably). The latter is the one I have now. It's strange because the board is printed with sa-36a (not pro) and its NOT using the older ta2020 tripath chip.

What do you think? Is this counterfeit, or SMSL changing the build? How would it measure up against the 2014 2.1 and 2.2 versions of sa-36a pro?

This build looks like a downgrade to me, but I don't know anything, I'm looking for some wordly input from those in the know here. Thanks

2 different units opened up here with slightly different builds.

Already for weeks I have been trying to build my first SE tube amp from old soviet TV parts. Tubes are 6P14P on amp and 6N2P on preamp. The amp is working only if I play super mildly and on low level. As soon as I pluck some string heavier a horrible distortion starts. I think I have tried everything - different resistor values, different OPT, different input and pot wiring. Gods are against me! Is there a mistake in schematic? Are the tubes bad? (I have few, all second hand, but from different sources so some of them have to be good.) Probably its just me, but where? Power transformer is 216 Vac on secondaries. B+ is 295 Vdc, B+1 after OPT 260 Vdc, B+ 260Vdc, B+3 = 130 Vdc, B+4= 150 Vdc. Filament Voltage 6.8 V. I have two OPT - one from same TV (measures 485 ohms on primaries, 2,8 ohms secondaries (so WR should be 13:1?)), other one from old radio (WR 23:1).
(The value of R14 is 200 K right now and input has 1 meg resistor that's not shown in schematic).

Can someone help? Thanks in advance.

Hello,
I use this preamplifier since a little more than a year. It was in the estate of my deceased elder brother.
It had suffered a flaw in the phono preamp, with one channel a lot lower than the other and you helped me solve it. (it was a dead electrolytic capacitor).
I was advised to change all the electrolytic caps in the device but did not proceed because I am afraid to break something.
Anyway, i live near a lot of FM broadcast stations (I'm on the only hill above the city... ) and I've noticed that one station is audible when I listen to a vinyl. If I'm not mistaken, it was not the case before, but I wont bet my life on this...
As the cart has been changed ( an old Grado with a Black2 diamond has given room for an AT VM95E cart), I thought I could play with the input impedance setting and the capacitance adapter switch but to no avail.
So I'm seeking advice here.
Many thanks in advance for your help.
Have a nice day and stay safe !

Sherwood S-402CP integrated amp, 1978-80, 35wpc. This amp has pre-out and main-in connections. It does not have a speaker relay. I thought that I had the ability to at least differentiate between signal carrying and power supply, but this circuit has me baffled.


I am referring to a group of four transistors TR304 through TR307, marked in red in the schematics below. I had to split this into two pics to show the entire circuit. The first pic shows that a lead straight off the secondary of the transformer which (I believe) is half-wave rectified and run through a couple resistors, feeds the base of TR304.

Please correct me if any of my assumptions are incorrect. The second pic shows that the outputs of TR306 and TR307 connect to the outputs of the Tone Amp.

What is the purpose of this circuit? Thanks in advance... 🙂

Are there any 3D tube meshes available? I can make envelopes pretty quickly just from an outline. Frank.Pocnet provides plenty of those. Filling the guts though could take a day or two per tube. I just want to plot my circuit while forming layout and the chassis. I don't want a tube used in my project until every connection is bolted down to its terminal block. If I try to jimmy it, I might die from clumsiness.

Here im gona post some pictures of my Holton build for the last couple of years.
Ounce you tried one, you cant stopp 😱

With the last order im up to 20 modules and one SmartDac.


Today i have Nxv-500R2 monoblocks for the midrange and tweeters.
For the bass system i have ordered another set of Nxv-500R2 modules for another set of monoblocks.
Speakers is Infinity RS1 and dipol bass is H baffel with 4 pc Peerless XLS 12" for each "tower"
Behringer DCX2496 crossover for midrange and bass. Tweeters have passive crossover, but some day some Nxv-200R2 monoblocks will be powering the Emit tweeters.

Sorry for the bad english writing.

Hi All.

I've been recently engaged with Crossover rejuvenation projects on a number of vintage Loudspeakers.

Part of this is to allow me to build up knowledge and expertise in Loudspeakers.

A member previously advised the use of Jaycar jumbo Speaker cable.
It's fig8 multi strand ofc speaker cable with 12/13 awg per core.
Peeling the two cores apart yields double the length.

Jumbo OFC Fig.8 Speaker Cable - Sold per metre | Jaycar Electronics

I was hoping to get advise as to which cable to use for internal Loudspeaker upgrades.

I don't know either way, but if it's decided internal wiring doesn't have an impact on reproduced sound, then I'd also be looking for things to avoid.
These might include high resistance, poor insulation properties, or other characteristics which might cause issues.
And/or are there wiring conventions such as color etc.

Also, are there cable tests which can be performed?

Not looking for state of the art, but rather best bang for buck solutions.

cheers

Cliff

here's the post

In a fit of tube fever, I purchased a Healthkit A7 amp that uses a pair of 12A6 beam tetrodes, along with other unusual tubes 5Y3 x1, 12SQ7 x1, 12SN7 x1, 12SL7 x1.

The 12A6 appears to be low power (6 watts in ultralinear) and is very inexpensive ($2-5 each, from what I've seen).

My original idea was to see how they sound for guitar, with the intention of making an inexpensive low-power push-pull guitar amp.

I'm wondering if this migh yield fruit for a guitar amp, or was delerious with tube DIY fever.

Any comments/suggestions/therapy will be greatly appreciated.

12A6 beam tetrode

Heater voltage 12.6V
Heater current 150mA
Max anode voltage 250V
Max screen voltage 250V
Max anode dissipation 7.5W
Max screen dissipation 1.5W

Hi.

Having a closer look at my Jamo Crossover.

The negative wires coming from the midrange and tweeter drivers meet together and then pass through 2 circuits on their way to the negative speaker terminal.

The first circuit contains an 18 ohm 5 watt Resistor.

The second circuit (in parallel) contains a Thermistor (PTC C995).

As they can be problematic, I'll be removing the Thermistor.

After removal of the Thermistor do I maintain that second path with a wire, or is the Resistor path enough to complete the circuit?


Thanks

Cliff

Seems ever post I make has to be approved by a moderator..
Do this end at some point?
Is there a number or time when it stops..

Tried searching to find answer but don't know what I should ask to find answer..

Thanks

Hi all, oprtr back.

I'd like to discuss a concrete example on EL84 operating points in triode vs pentode mode:

Why is it that all of the spec sheets insist that when those babies are triode operated that Rk should be higher and thus the bias lower. Aren't the current swings supposed to be lower and thus safer when running the tubes in class A, triode or not.

I have measured both plate and grid current and dissipation with the tubes cathode biased at 98% and it was perfect. I guess everyone worries about the screen grid, but even at max plate bias the screen was well below the 2W dissipation with no swings.



VS



What am I missing 😡

Hi everyone,

I posted this in the photo thread but later realised that it would be better to have it's own thread in case there is any discussion which would disrupt the photo thread. Just thought I'd share my first amp project, a tube headphone amp with integrated DAC.

The amplifier is based off a well-known OTL amp circuit which utilises 12AU7/ECC82 input & 6080 triodes and is output transformerless (OTL). It should pair nicely with the high input impedance of my my Sennheiser HD6xx headphones. Input options are either switchable line level analogue or USB digital. Digital input is provided via Khadas Tone Board. It currently has GEC CV 2984(6080) and GE 12AU7 tubes installed, these are just what we had easily available at the tim eof building and I had planned to upgrade them. After some research it seems the CV 2984 is fairly well regarded and an upgrade would be quite costly, but i'm interested in any recommendations.

This amp will predominantly reside on my desk at work, the decision was made to integrate a high quality DAC as I have found the sound output of modern office PCs to be quite poor.

I’m very happy with how it turned out. I've attached some pics below but there are more pics and full build documentation on my blog if anyone is interested. OTL Headphone Amplifier / DAC – Jeremy Young Design

Cheers,
Jeremy

D'Agostino Relentless Mono Power Amplifier | Hi-Fi News

In use you'll regularly see that needle flicking up beyond 300W, but this is 'fake news' - the meters are made to move all the time so that 'users are confident something is going on', admitted Dan, 'fun to look at, but please don't take the numbers too seriously'.
Decorative By Design
Why? Simply put, the early Momentum amplifiers had accurate meters and, with typical real-world outputs being just a few watts for much of the time, the needles were barely moving.

Click to expand...

what is this, a toy? and this on:

So this is the first and possibly the only full and independent technical test you will read of the hi-fi world's most luxurious, most powerful, heaviest and costliest amplifier... ever.

Click to expand...

Yo, good morning/evening/night. Im very new to these audio things and I searched for something like "Tri-amped amplifier and just found almost nothing, only wikipedia and desc, but I want to get some good one
I have a set of a 10" sub, a 4" mid and a 6" tweeter (2 of each, stereo sound), so I dont really want something loud asf, I just want the best audio fidelity I can get of them (plan to use for mixing) , I'm whillin to pay at the maximum 100U$D
Also, I am using a very very very very old amplifier, Philco - Hitachi PSR 60, Is sounds pretty good, I used to mix on it so anything 2x better than him (doesnt need to be loud as him, I use him at 1-5 volume (from 1 to 10) also, my speakers are 8ohms
Thank you for the attention 🙂

Hello everyone,

I am new to diy audio and have been researching and dreaming of speaker design for quite a while and now the time has come for me to make my first speaker and would love some help and answers from the diyaudio community. I have decided on a closed box, 2 way design to keep things nice and easy for my first attempt. I've decided on the drivers, the tweeter being a vifa XT25BG60-04 and a SB13PFC25-04 for the mid/sub I have attached the spec sheets below. My reasons for selecting these drivers was 1. Budget 2.i had heard good things about them mainly internet reviews and comments and 3. They seem a reasonable match for a crossover for a two way (at 2khz). as a newbie i would love to hear any opinions on this.

The main questions I have concerning the drivers is power ratings. The woofer is rated at 40w (rated power handling) and the tweeter is rated at 100w (rated noise power). Are these the same? And if so is the difference in the power rating a problem?.

The other power rating questions I have is to do with crossover components. I have designed the crossover and all its different values. But i'm a bit confused by the power rating of components like resistors etc. should the components be rated the same as the drivers eg: 40w for woofer and 100w for tweeter?. Or is it the same wattage for the whole crossover? Does anyone know of any guides for this?

Cheers everyone hope to hear from you all soon.

Hello! I have an old Nakamichi DAC-101 that i would like to run in NOS. The digital filter YM3414 (4 or 8times OS) split the I2s signal to one left and one right . The left signal comes to the dac TDA1541A-S1 like one "left normall" and one "left inverted". The right signal goes to it's dac in the same way as the left do. I need to find a device that can replace the digital filter. I only want the I2s signal to be splited in left and right without filtering or OS. I send the schematic for you people to see.

Hello!

Op-Amps would be perfect to drive and control power amplifiers
if it wasn't for one thing:
- they work at too low voltage when it comes to higher power.

With the method I will show you, you can drive a power amp
even from an opamp working from +5/-5 Volt supply.

First, opamps can often put out 20-40 mA.
OPA134, which I have used for my SPICE, puts out 35-40 mA.
This is more than enough to drive one power output stage.
A triple Darlington needs no more than like 0.1 mA for plenty of Watt out.
One ordinary Darlington (driver + power transistor)
should do well on a couple of mA. Maybe max 5 mA in worst case.

This tells us, that there is no need to amplify the current from Op Amp.
We can let the output current, as it is, drive the power amplifier output.


If you look at my diagram, you see the opamp output is split in 2 halves
and via foldback transistors fed to the output.
The blue lines show the path.

I have done SPICE for 100 W/8 Ohm 200W/4 Ohm with great results and performance.
OPA134 is good enough for this job.
I think you should have a look att this method if you are intesrested.

Regards Lineup

First off a thank you to all the hobbyist who contribute to the diy HiFi community. I was hoping you guys may be able to shed some light on a question I have pertaining to Troels 5" Seas design using the the 22TAF/G tweeter SEAS 5INCH . I have the CA15RLY driver but not the tweeter. What I do have is the Seas 19TFF1(H737) and the Seas 27TFFC(H0881) tweeters. I am sure by now you know my question. What if any mods would be recommended to the crossover to use one or the other? I do not have the crossover skills some on this website have. I can build cabinets, wire up crossovers and put everything together. Just do not have the crossover design skills. I am more of a kit builder. This design will be built to Troels specs except for the tweeter mod in the crossover. Thank you for any help you can give me

Hi,

I found a box that that seems to be part of a moviola editing machine or 16mm transfer system. Inside the box is an amp consisting of a 12AX7 , then a 6J6 and a single 6AQ5A power amp.

Both sides of the 12AX7 are being used, before and after the volume pot, but only 1 side of the 6J6, which then goes in to the grid of the 6AQ5A.

The input of the amp is a monophonic tape head going straight in to the grid of the 12AX7 and the output is to a 49.7:1 transformer and 4 ohm speaker. There are no controls other than the volume/power switch.

Could anyone suggest what the purpose of the 6J6 could be?

Thanks

the schematic is attached below for further examination

i have a 10k log pot

i need it to behave as 0-33k from wiper to out
and 0-220k from wiper to ground

if i add a 68k resistors in series with the output lug and then parallel the end of it with the wiper using another 68k resistor

and placing a 220k series resistor in the ground lug then strapping in parallel the exit with the wiper

then will it behave the way i described?

Hi Everyone,

I've built a lot of single ended gear using el84's, 2A3's, and 6B4G's. and I've owned/repaired/modded single ended gear using 6V6's, 6L6's, EL34's, KT88's, and 300B's. I've owned a few PP using 6L6's, EL34's, and EL84's.

Overall I've enjoyed the sound of the SE el84's and 2A3/6B4G's the most but I am starting to miss the bottom end and being able to use a variety of speakers. I have a bit of money at the moment I can use for audio and I'm debating what I should pursue.

The reason I've been thinking about a 6B4G PP is because I've heard a lot of people, that I respect their opinion, say they've really enjoyed them, even though it's PP they still seem to have a pretty high 2nd harmonic, it would give me some extra power to play with, better bottom end performance since it's PP. The down side would be the added expenses of 4 output tubes, and possibly making the circuit more complex by going with CCS and DC heater filaments. (with high efficiency speakers I really like having a very low noise floor, my el84 amp is 30 Db if I'm remembering correctly)

One other project I'm considering is modding my el84 monoblocks to run with either el84's or 6B4G's and then using my minidsp as a crossover with subs. I have James Audio outputs in it so I have multiple taps and could run both tubes at the their preferred output tap. I just know from past experience I would have to go DC for the 6B4G's filaments. Also I'm not sure if it's possible to have one driver stage that would work equally well for both tubes or if I would have to have to do separate driver stages.

Currently speaker wise my tube amps drive either my econowaved ElectroVoice Aristocrats or my Klipsch RP600's. I was gifted some custom speakers by a friend that have 21" woofers and enormous JBL mid horns but, one of the woofer's voice coils is rubbing 🙁 so they've just been sitting, also they're enormous and I don't really have the space to set them up properly. My only other speakers are my McIntosh XR 1051, after I recapped them I really enjoyed them (they mate very well with a Citation 16 I rebuilt from the ground up).

Also part of me thinks I'm a little insane for starting another audio project when I have about 6 other audio projects I have parts for but, the idea of building my first PP and getting 6B4G sound with more power and bottom end is an exciting thought.

The reason I was thinking about toroidy's outputs is because I like the idea of an extended frequency response and people that use them seem to be very happy with them. I do know that I would have to be careful of balancing the DC with a PP so I was thinking about using CCS to keep it balanced. In the end even if I don't go for the PP 6B4G I think I would still pick up a SE output from them just to play with. I am curious if I could squeeze more bottom end out of a SE el84 with one of their OT.

As a side note, that I might make another thread about is, my 6336a SET amp. I've noticed when comparing it to my other amps the mid-range seems muffled and I'm wondering if it's because of the driver stage (it's only using half of a 6SL7) or maybe that's just the sound of the 6336a? I'm wondering if I should mod it or just move onto something else.

Sorry for the long post there's just a bunch of factors effecting this decision for me.

As always any thoughts, ideas, input, is greatly appreciated

Hello,

i got a Yamaha M50 on the healing bench, but i cannot find a schematic for it.


One of the channel the 2SC2581 are shorted and the 0,33 ohm resistors are open. not sure if anything else is blown, was about to check with the schematic on hand before going in blind.



elektrotanya and hifiengine provides a service manual which mentions schematics on page 14.. but the scans i found only go to page 11.


Does anyone know a source for a full service manual or have one?

ive seen schematics on radiomuseum but you gotta apply for paid membership to see them...


thanks in advance!

I have the Parasound p5 preamp and the Marantz cd5004 cd player both, with headphone outputs would either of those be enough to drive the Massdrop x Sennheiser HD 6XX Headphones with 300 ohm impedance? Thanks! 🙂

Hello all,
I have a Hickok 539A tube tester with a busted transconductance meter. Exact replacements seem to be very difficult to find, but I’m thinking of replacing the meter with one from another Hickok tester, if I can find one, and swap in the scale from the original meter. This is providing the new meter has the same physical dimensions as the original of course, also as far as the scale is concerned.
Do any of you happen to know of Hickok meters that would fit? And still have the original outer appearance? The manual unfortunately doesn’t mention which type of meter was used. Judging from pictures, the 532 or 600 seem to look alike to me, but I’m not sure.
The replacement meter will probably be less sensitive, but that could be compensated for with a suitable opamp circuit, so that wouldn’t be a dealbreaker.
I’m looking forward to hearing if you have any info on this.
Thanks...

hi - i was thinking of using the above with a small chinese tube amp

1. its not clear in the info- does the twin have two cones or two drivers- ie coaxial?

if twin cone-what kind of whizzer is that?

2. treble quoted at 18k - but no fr graph is offered- could the treble really be acceptable from an old large driver?

many thanks

Hello everyone,

sorry if I ask silly questions. I'm new to this stuff and English is not my native language what makes it a bit more complicated.

The bottom line is can I make it work? I want to connect Speakers and subwoofer to Samsung Smart TV.

1) I got those speakers without middle part. Originally they were for karaoke system with two mics. That's why each speaker has mono 1/8 (3.5mm) jack (see on pic).

2) I got subwoofer. Check details on the picture.

3) I got adapter to have connection from TV to speakers through optical output (see on pic).

The problems are:
1) Speakers have 3.5 jacks but subwoofer doesn't.
2) Speakers have 3 ohm.
3) Maybe more problems, let me know))

Can any of you see how it might work? Should I buy something in between? Cut jacks and insert to subwoofer (high level output)?
Or those won't work together and I should quit?

I will be thankful for any ideas!!!

Thank you!!!