Hello, I have two wonderful Morel 5” drivers for sale. These were purchased for test fitment in some line arrays before committing to all 20 drivers. They have never been powered and may only show light mounting marks or dust.

Morel MSW144 $100 shipped in the USA
Morel CAW538 $115 shipped in the USA

Thank you!

Do you ever grab the router for this, even if you have a table saw? Are both methods just as well.

What is your primary source of weaponry for cutting panels?

Is it a crazy idea to use a router primarily for cutting all the needed cabinet panels. With 1/4" jig and a straight edge for guidance. If you use a fresh carbide it should only need a light sanding before assembly. And one or two passes if the router is powerful enough.

I remember someone looking for a Spectral DMA 50 schematic. I have one from Nelson via a customer that couldn't get it fixed.
I generated a schematic from the board. It is pretty close I may have a part or a connection in the wrong place. This is just the front end.
A pretty nice amp with low noise and distortion in the working channel. It's bandwidth exceeds 200K the limits of my AP. A nice 100 Watt amp in a compact package.
The outputs are four Hitachi Mosfets per channel.

OK- so I have a Xantech 1235X which I have dumped gallons of contact/electronics cleaner through its mint on the inside but still pops my CD's when powered on.
I have a POS Pyle 12 Channel Class D PT12050CH but noise floor is so bad I want to run it over with my suv.

I need channels to power my DIY speakers actively- As of right now I use 6 separate channels for drivers, but soon that will jump to needing 14 or more as the woofers i want to feed 100w-

Is there a amp that i can just drop in replace say the Xantechs with or a amp board that can easily be wired by an idiot like me to like 1-2 SMPS or Toroidal.

I don't have thousands to drop on a stupid multi channel amp- I just need an affordable/cheap 50W per @8Ohm with option to bridge and noise floor thats not ungodly.

I have way to many kids and working 10hr days so taking hours to make my brain bigger with learning all the ins and outs aint happening. Yes Ive been on Dayton Audio I already tried the Wondom/Sure 6 channel and its was gross noise floor. I tried "daytons" adau1701 DSP chip and it introduced train levels of noise so I wont even try "their" amps.

Hello, a couple of weeks ago I was on this site trying to get some help to better understand the inner workings of this amplifier. I purchased a scope and wanted to learn how to use it. The amplifier has a hum from both speakers with nothing connected to the inputs. I will attach some pics of the internals hoping someone can see any faults with my wiring and make some change recommendations ............also I am using a 20volt antek transformer instead of the recommended 18volt.. would appreciate any help thanks.

I finished rebuilding a Marantz 500 and I’m wanting to make sure I get the bias done correctly. The instructions are a bit difficult.




After feeding a 20 kHz signal until I got 4.5v output I got no change to the waveform as far as “large peaks indistinguishable from the distortion”. I read that someone was setting each channel for 14.5w of power consumption at idle, but that’s somewhat difficult with it having a 10w drift. I’m measuring across one of the emitter resistors and would like to calculate for bias current.

Also, the instructions don’t say, but should bias be set before the amp has a chance to warm up? I did a Kyrocera that insisted on having the bias set within the first 2 minutes of power up.

What’s a good number to shoot for? At what I felt was close to 15w consumption I was seeing about 3 mV across the .15 ohm emitter resistor which is about 20 mA. It did fluctuate, liming to 4.4 mV (30mA) and then back down to 3 mV after about an hour of being powered up.

I’d like an idea of how much current once warmed? 15-20 mA? A little higher, 20–25?

I guess anything is better than where it was at, they had 4.7 kohm resistors in which was giving me a reading of about 0.25 mA, so it was way under biased.

Dan

Hello guys,

I'm facing a kind of dumb problem here. I'm tryng to build a passive stereo volume controller to use on stage, just so I can attenuate the volume when the band is playing too loud and vice-versa.
It should be basically the input -> pot -> output, right?

But the problem is that, at max vol in the pot it all works fine, but when I turn it down a little bit, the volume drops a lot. For a 2% turn down in the pot I have a 95% decrease of the volume.

I've tried both log and linear pots, 10K and 50K, getting the sound from my mixer and from my laptop, all gave me the same result. The ground from both sides of the pot are connected, input on the right side and output on the center.

Any ideas what would be happening?

I've attached some pictures of my prototype.

Thanks a lot.

Hi, I’m interesting getting back into vinyl again. I’ve settled on the Pro-ject Debut Carbon EVO turntable with the Sumiko Rainier (mm) cartridge. The turntable doesn’t come with a built in preamp so I need to find one. Which brings me to my question, what phono preamp are you using with your ACP+?

Hello all,
I need some advice on a situation I've gotten myself into. I restored an A-1020 that I found online (blown outputs and resistors) as well as completed a full recap. Everything was all and good for about two months until I pushed the class A button. Fuse blew and protection was activated. With the little "driver boards" out, I can prevent the fuse from blowing, but I still have -5vdc and -15vdc across the outputs which is keeping it locked in protection. I've been digging for the source of this dc in the signal path and I'm coming up empty handed and confused. I'll note some of the places I've found the voltage and been stumped.



Between C208 and C210 I measure 4.25vdc, which seems to be the beginning of where I find it, but it can only come from the node right of R212 which is connected to so many other things I'm not even sure where to start looking next.

In addition, D214 is supposed to have -60vdc on the anode and 1.7 on the cathode (which connects to points e, b, and c to control the transistors on the now disconnected driver board)...yet I get postitive 62vdc on the cathode...which is nearly full rail voltage. No idea where it's coming from since the only other point connecting to that diode is C230, which has 0V on the leg connected to the ground bus and the same +62vdc on the leg connected to D214s anode. The dc seems to appear put of nowhere.

I'm at a bit of a loss here hoping one of you kind folks can point me in the right direction.

I was in need of some transistors to replace the shorted 2SA1169 and 2SC2773 (XM20) outputs in a Yamaha R-1000. I posted a thread at Audiokarma looking for assistance and a very kind forum member messaged me and basically told me he bought out the stock when they were announced to go extinct. He sold me 4 pair, 4 2SA1494 and 4 2SC3858 (MT-200), enough to do two amplifiers. Drop in replacements. Unfortunately I went through them, I repaired two of these R-1000s with shorted outputs. I’m in need of more and instead of going back to ask if he would sell me more, I thought I’d see if I could find a modern replacement that will work with a retrofit.

Below is the NPN I’m trying to replace in the Yamaha.



I’ve looked through parts I have and I believe this may be the closest I have.



Only concerning looking thing to me would be the emitter-base voltage max, 6V vs 5V, which looks like it won’t be an issue in this amp, should be under a volt. Otherwise the replacement is more robust all around. Couldn’t I technically drill and tap a new hole and get this pair to work?

Here is the device that was sent to me and I used in the other two R-1000s.


I’ll keep looking myself, but does anyone know a pair of devices that would be a good go to for these since they’re no longer available?

Dan

Hi ... can someone help with speaker box influence on frequency?
I'd like to know at what general point does the box/horn/OB, etc. have little or no effect on the sound.
Some say 200hz. I need for all types of enclosures as some may differ.
Thanks, Zene

I need to reduce the value of my (shared) Cathode Resistor, to increase the bias, per pair of KT88 output tubes.

Presently, the Cathode Resistor comprises two 750K/12W wirewound resistors in parallel, combined to deliver 375K/24W.

With 370V measured from Cathode to Anode - and 40V measured across the Cathode Resistor at idle - the KT88 tubes are currently operating well below 50% of maximum dissipation.

To increase the bias, I need to bring the Cathode Resistor down to at least 300K, which is very easy to achieve by adding a third resistor in parallel - at a value of 1.5-Megaohms.

QUESTION: What minimum WATTAGE does the third paralleled resistor need to be, in order to maintain around 24W of power handling at this Cathode Resistor?

Apologies that my extensive scouring of the Internet has not been able to unearth a definitive answer...

Purchased a couple of these at an electronics surplus store. The number indicates a Nichicon film capacitor but why the "S" marking?

?

I was wondering if any of you have used the dual power supply available from JameCo here. A +/- 5-15v Dc adjustable supply kit supporting up to 750mA per channel. It's a whopping $35US, and should be beefy enough for a few varied projects.

I'm ordering PCBs for the Muffsy Clone from the SlowDiyer and was thinking this could make a decent linear power supply for the phono stage.
Any Thoughts?

Can anybody help, I have recently got hold of a cambridge 640h music server but it is not working,may be hdd problem.I have managed to get a 640h blaster disc with operating system on from richer sounds but i can not get it to load in the server can it be done in a pc using windows xp and if so how.any help would be appreciated. thanks brian.

Jut found this in my colection,dont used for some years now but in verry nice condition and original terminated with silent cardas conectors.This is verry musical cable ,neutral in character with hint of warmt and top transarency.2 x 1 meter lenght.Price 150 eu including shipping with track to EU!

Hey Everyone, Im a noob for the most part when it comes to building amplifiers. I have successfully built an amplifier using LM3886. Sounds great. Recently I have built a new amp by bridging the lm3886. I am using my iphone as a music source. My question is this: At some point I must be losing power by running 2 chips on each channel plus a powered subwoofer. What would be a good way to amplify the sound source and maintain sound quality ? Can someone point me in the right direction? Any help would be greatly appreciated.

Hello. I asked myself the following question about the balanced inputs and/or outputs in the preamplifiers.
What advantages do they have since I suppose that somewhere along the path of this signal it becomes unbalanced, mainly in the power stage of an amplifier, unless it is a bridged amplifier.
This question arises because I have purchased an IFI Zen Phono phono preamplifier.
The factory, among other characteristics, states that it presents balanced circuits and even apart from unbalanced rca outputs, it has balanced outputs through a special connector.
Greetings and thanks to whoever clarifies it for me.
https://ifi-audio.com/products/zen-phono/

Is the DSO1511E+ still the favored low cost, shove it into your pocket like a multimeter, scope these days? This would be for testing simple factors in various places where dragging and setting up a real oscilloscope would be a PITA. The battery powering and associated isolation is of course a real bonus here.

Hello everyone, i ask you what that Alphasonik's board can be.

Hi.

Im struggling with a very basic full-bridge setup. Feedback is a UCD-style back to both inputs of an lm311. No matter what feedback arrangement i try, i get the same odd waveforms when looking at the 2 half bridges individually. When looking at the actual differential signal between the half bridges it looks better, but still odd.

The behaviour is load-dependant. With light/no load the waveform are very good and sine-like. With load and low levels the waveform are also ok. Based on simulator models I have a strong feeling that the change on the sine-wave is where the output inductor goes from continuous to discontinuous mode. Any ideas on what to look for? My control-theory is light-years away from doing a full analysis of this.

First picture is output from the 2 half bridges. Second is a zoom on the point where the sine changes. I realize it's a bit hard to fully see

Can supply schematics later, but it's very basic.

Not looking for ultrahifi. Just stable performance for a sub. -ans some learning🙂

Kind regards TroelsM

Hello

This is my first class D build and it's giving me some issues.

With no input signal and a speaker attached, it will give me a siren/tea kettle sound.

If I input a 40hz tone to the amp, then looking at the output (with speaker connected), it looks like the upper half of the sine wave is not rising correctly, the lower half looks ok?

Looking at the output of the MOSFETs before the LC filter, with no signal input, I do get R-R oscillation but it is in what appears to be pulses. Is this normal? Or should it be continuous.

Another thing I noticed is that the more volume I give the amp, I see the V+ rail start climbing. My rails are +/- 54V, positive rail will climb to 77V whereas the negative rail will stay around 54V give or take a few tenths. When the positive rail hits ~77V the amp will start making a popping sound. If I decrease or remove audio, the positive rail will fall back to 54V and it will stop popping but continue making a tea kettle noise.

I've attached some scope images and schematic.

Note: In the schematic I made a mistake for VCC 12V power. It is referenced to ground. In the actual circuit I am using another power supply referenced to V- rail to VCC. I am also only using 1 pair of output FETs at the moment.

Thanks

Hi,

Currently have a Threshold SL10 preamp with the following updates:

• All electrolytic capacitors in the preamp module were changed for Elna Silmic II capacitors, considered among the very best for audio applications
• The resistors in the phono input section were changed to Vishay Dale metal film
• All RCA input jacks were replaced with gold plated copper units
• The volume potentiometer was replaced with an Alps BLUE
• All input/output wiring replaced with foamed teflon insulated Single Crystal continuous cast oxygen free copper wire
• The balance control was taken out of the circuit.
• Electrolytics in the power supply were replaced with high quality units of higher capacitance (this went up from 13,800 mF to 24,000 mF)
• The diodes in the power supply were replaced with ultra fast soft recovery hex fred
• The connecting cable between power supply and preamp was upgraded with higher AWG teflon insulated pure copper wire.
• The IEC connector was replaced with a gold plated copper unit.

The unit sounds excellent but this might be an opportunity to invest in a rare Threshold Fet10e + Fet10pe combination. I have not read about any comparisons between the SL10 and two-unit Fet10 combination.


Given the system is solely turntable based, can anyone given some direction on if it would be worth investing in a Threshold Fet10e line level + Fet10pe phono combination or would this be a lateral move rather than an upgrade.

Thanks for your help.

P.S.
Amp is a Threshold S/500 II
Cartridge is ZYX Airy 3 (0.34mv output)
Sound Lab A-3's

I bought and rebuilt this Technics SL-B2 turntable recently. It's been running great but I'm unable to identify what accessory is solidly glued to the back left corner? It appears that some sort of post would slide into the hole in the middle and be held in place by the long screw that protrudes slightly into the center hole. The other screw is shorter and does nothing I can identify. The screws and entire assembly are non-magnetic so I suspect it's built of brass or aluminum.

Google image search hasn't been able to identify it nor have I found it on Audio Technica's website. I plan to remove this and clean the area but my curiosity would really like to know what it was for!

I picked up a pair of CK647 tubes at a local military surplus place, as they looked like dual triodes and were cheap. They look like a tall 12AX7, and after some testing with multimeter and tube tester, appeared indeed to be function as dual triode with same pinout as 12AX7 and other similar 9 pin dual triodes. So I went out on a limb and put one in an amp in place of a 12AX7 and it sounded great, maybe a tad less gain than a 12AX7 but louder than a 12AU7, and great tone. I couldn't find any specs on this tube on any of the standard internet tube data sites, so does anyone have any information on this tube?

i just got this used box as a gift
the specs says 400 watts for LF duty
is a reflex system

specs below

• Subwoofer Freq. Response: 40 Hz; 120 Hz +/- 3dB
• Sound Pressure Level (1w/1m): 102 dB (half space)
• Max. SPL: 127 dB @1% THD
• Weight: 120 lbs
• Dimensions (Transport): 28" (H) x 19" (W) x 23" (D)

can i swap that 15" for a High Power driver and bypass the internal amp with a 3kw rack amp i have collecting dust
to coax out some more SPL ? of the box

i have the amp already, just need to invest on a suitable highpower driver.
any candidate drivers ?

I was looking at 15tbx100 but recommended vented box volume was around 3.5cuft and the B-52 box is almost 8cuft , i guess some less volume cause I was using the external dimensions , less the plate amp and some bracing , maybe 6cuft.

One channel of a pair both in December 2015 became open circuit recently.This occurs suddenly and no physical abuse by heavy loud music .
This is traced to corrosion of the coil wire at the glue junction. See the whitish powder . The speaker was subsequently repaired locally
Please see picture.


Has anyone else has similar experience?
Any advice on how to avoid similar fate to the other driver?
I measure 6 R across the terminals for both pair even though the speaker is spec at 8R. Is this usual ?

Is your 26mm MDF speaker cabinet resonating like a church bell despite substancial bracing - try this CLD sandwich technique!

This should reduce any nasty peaks and vibrations that might show up in later measurements.

I did not do the whole inside because volume is low as it is. I did not enjoy reducing the depth of the cabinet even more, but something had to be done about this ringing. Bracing is there, and as much as I dare to have, not to create separate compartments within the compartment.

Inspired by the excellent sound of Devore Orangutan O/96, I only put a patch of recycled denim damping material behind each driver, and a small one on the bottom. I don’t want it unaturally dead. More like Schrödinger’s cat dead.

I will avoid polyfill, but might throw in a used merino wool sweater.

Here is before and after, of me finger tapping my woofer cabinet. No music yet, but I expect crap since these cabinets are too small for two pairs of W26FX002 woofers.
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References:
Where did I get this idea? Scroll to the last experiment.
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Hi guys,

I wanted to share with you this teardown of a Inhaos LP2010 low-pass filter for class-D measurements. If any of you decides to design one like it, please make it open hardware!

I love this little device. It can easily be configured for 20Vpp or 50Vpp input with some series resistors.

In an effort to reduce B+ (chifi 110v ps in a 120v country) i made some changes most notable was the cathode resistor of 680 ohms to 1k ohms. The cathode current dropped from 90ma to 70ma.
Was working on whats required to get it to the 80ma range and thought now might be a good time to see if i could add in a pot on both cathodes making the bias somewhat adjustable.
Knowing I know only enough to make many mistakes figured i should see how its been done before.
My search terms are giving me nothing too usefull..
My thinking was to add a 20k pot in parallel with the cathode to ground, figuring I probably forgot something...

Anyone have any scematic examples of how this is done?

This is a small, simple British amp I just bought cheap. Previous owner had spray painted it black, so I cleaned that off. I've ordered some adapters for the DIN connectors, so haven't been able to listen to it yet, but it does power up and seller said it works great.

Opened her up and inside is nice and clean, all components are original.

I'm debating whether I should recap this thing, I'll decide after I listen to it play music I guess.

I can't find any info on this amp or a schematic, the design looks similar to the JLH 1969 amp to my eyes.


Anyone know anything about this amp?

This is my second DIY tone arm. Based on schroder design with magnetic tread bearing but with some changes.
The arm pivot is stabilized with dual tread architecture and arm gymbal geometric center is achieved with sphere shaped magnet. Antiscating and azimuth can be adjusted while playing.

Hello Everyone,
This is my first project for experiment on avr microcontroller, Hope this helps and any comment I will Thanks for you advanced.


Source Code over there is HERE>

Hi , everybody,Im new to this site. I have a Ampeg SVT150H and my problem is : when looking at the trace on the scope the positive half cycle clips when o/p
reaches certain level. All ic's, caps and output transstors have been changed but fault persists. Anyone got any ideas? Thanks in advace. A.S.

I got an old CRT analog oscilloscope recently and it's acting a little odd. When using the built-in calibration square wave, the right side of it seems compressed, as if the wave has a higher frequency on the right side of the screen. I've tried a different probe and that's not the problem. Any suggestions of what it could be?

Dear all,


for the last couple of years i have read and found a lot of interesting topics about horns, hifi, amps and other interessting stuff about my hobby (and small business by now next to my full time job as an optics engineer) on this website. Finally i decided to join your community as well and i am very excited to learn and share!


Sadly i directly have to come up with a question on the Hiraga 30W Amplifier...


Short background on the history:


I am running two of those beatiful amps already, which i have build years ago with an friend of mine, who has passed away too early sadly. Now i wanted to give it another try on my own, because i am really fascinated by the sound of these amps and i wanted to learn more about electronics and i have better capabilities to manufacture nice enclosures.


I found the PCB's on Ebay three years ago, a week ago i decided i wanted to finalize the amps already.... It's the blue ones with the little monster printed on them (no link anymore, but see pic's attached). Meanwhile i have found out, that they are very similar (but not identical) to those ones available here:


Hiraga 30W A class Amplifier - HiFiStor


But they are not completly similar, because

- the driver transistors 2SA634 and 2SC1096 are different in my kit.

The power supply came with transistors instead of diodes.

The output transistors were off as well (2SC5198 and 2SA1941 instead of 5200 and 1943)

All in all, looking back, i am afraid the ebay kit was a wierd mix of transistors and PCB's and a knock off....



The Problem:


I have checked the circuit and values of resistors several times. Both channels behave similarly. My Power Supply runs at +-34V with lots of capacitors (see picture), so that should work fine.

I nevertheless only measure a very small voltage across the 0.33R resistor with 47k Resistors as R3 and R2 in place (from schematic in the link above). Putting a 200k Stereopoti in parallel allows me to increase the Voltage drop across R12/R13 (its the 0.33R ones) to around 0.2V to 0.25V (quasi cold state). Slowly lowering the resistance further, all of the sudden i can hear a "plop" and one of the two power transistors shorts and is broken (i think by then i am around 33k in total). They are attached to rather large Fischer Heatsinks (see pictures). The 300R resistor R18 looks a little brownish by now.
I have checked the 0.6mV across Q4 & Q3 and that looks fine. There is supposed to be a Voltage at R10 & R9 of around 1V (1mA@1k from the original Hiraga schematic), which seems to be a little low at my setup with around 0.65V. The zener-diodes show 22.0V, as supposed to be.



I am thinking that my transistors 2SA940 and 2SC2073 do not fit well as the drivers. The datasheets are hard to compare (for me and my limited knowledge/experience) because the data given does not match (Voltages and currents where the Data is given varies, see attached pdfs).


So my question now is:

Can anyone help me to find out what goes wrong here?
Is it worth changing the drivers to the 634/1096 ones?

Might it be a problem of matching the input transistors?

Waht am i overlooking, because the problem occurs in both channels?
How can i systematically track the error (i do not know which voltages should be where without simulation the circuit?)



I am a little lost beacuse i am in the wierd state of generally understanding how a transistor works, but still beeing (massively 😉 ) overwhelmed with analyzing schematics to great detail. And then there are three versions of this amp (my old one, the ebay one which is the problem, the linked one) with different transistors and resistorvalues, which dont make it easier to truly understand the important parts of the circuit.


Sorry for the long story and thanks a lot for your support!



For a better understanding i have attached a few pictures of the amplifer.

We have been talking for long time, and i asked him to let me post some schematics.

Those circuits i did not assemble, so, i cannot evaluate, as not hearing i have not this condition.

As Bora is experienced, i suppose he had constructed some prototypes.

Now, presenting Bora to forum friends.

regards,

Carlos

Need a single HMF200 in proper working order.

Hello,

which is the most sensitive / loudest 1x18" design, regardless of size or speaker, 30-120Hz roughly ?

I wonder which one it is, Martin audio ?

cheers

My mother has early stage memory loss and bad judgment and after discussing with a friend he sent me this video,it changed my perspective,hope it does the same to you.
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I noticed that TO 92 package component ( details were erased ) 1st and 2nd pins are normally closed, when the negative supply - 7v has been given to the 3rd pin slowly 1st and 2nd pins slowly turn in normal opened. kindly help me to identify the component

Counterpoint sa-100 Upgrade version

Hi all
I have this turntable. There is a very little info available. The SP 12 was Japan specific model and produced in very limited quantities. I am looking to build a plinth for the TT. It would be good if someone here help me finding a plinth plan for the TT.
Here are few pics of my TT



and a video
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Regards
Sachin

Hello all, I have always been a fan of the hybrid amps, Llano Trinity, Moscode 600 are the two I'm most familiar with. I'm not an electrical engineer or audio guru, just a kit builder that can follow directions.

My question is, are there any of these power amp boards that could be easily used with a tube driver stage? I was looking at the "Honey Badger" kit, has anybody here done this before? I have a couple different driver stages I would like to "marry" to a high output amp. I have a couple of the boards for the upgraded Dynaco ST-70, one using 12AU7, the other using 6SN7, and then the Llano type is simple to build.

Any thoughts or advice would be appreciated,
Thanks,

Replace INFINEON Audio IC IRS2092 IRS20957

Car amplifiers are electronic devices that increase the power of the car audio system signals that pass through it. Car amplifiers manufacturers need to use some audio ICs, IGBT, Mosfet and Diodes as following:

• SMD C.I. DRIVER DIGITAL IRS2092STR SOIC-16
• SMD CI DRIVER DIGITAL SOIC16 IRS20957STRPBF
• IGBT FGL40N120ANDTU
• IGBT FGH60T65SQD-F155-D
• Mosfet IRLML2244TRPbF
• Mosfet IRLML9303TRPBF

Previously, these mosfet or audio ICs are mainly supplied by Infineon and Texas. The lead time of INFINEON or Texas is normally 30 to 50 weeks. Car amplifiers factories suffer a lot of bad lead time and unstable prices, especially in 2021.

Topdiode Manufacturer, a Chinese active components manufacturers since 1996 are very professional in providing solutions for car amplifiers and audio cross over circuit.

Topdiode offer replacement of INFINEON Audio IC IRS2092 IRS20957, and lead time only take 5 weeks.

Here it is:
Topdiode Audio IC7012 replace IR_INFINEON [IRS2092STRPBF
Topdiode Audio IC NSA2092 SOIC16 replace IR_INFINEON [IRS2092STRPBF
Topdiode IGBT 40TD120WW TO-264 REPLACE IGBT FGL40N120ANDTU

website： www.topdiode.com

Hi, im looking to buy above mentioned transistors, matched!
Anyone have some of these or know where one can find them matched?

Hi all,

I'm going to purchase some of Merlin's Universal PCBs to use, and, to try to extract some of his wisdom regarding the way he solved the design problem.

I know chassis layout is a huge part of building an amplifier so the way the PCB is laid out will also be critical. Avoiding ground loops, using star grounds sensibly is high on my priority list. I know ground planes don't really make sense at audio frequencies.

But other than that, are there any general advice for laying out PCBs for valve amplifiers? For example: track thicknesses, maintaining separation between signal carrying track and sources of noise, where to use metallisation, should certain tracks be separated along the front and back of the board?

I am mostly coming from guitar amplifier perspective so I will have a few gain stages, EQ, phase splitter, power section and power supply.

Quite a broad topic, I'm mainly interested in any wisdom I can gather before starting so I don't have to repeat mistakes others have encountered! But also knowing why to do things is a certain way is important I think.

I am looking to buy 2 pieces of said amp module. Does anyone know where I can get them? They don't seem to be available to the general public.

TY, Alexander

Hi everyone .
Do you think it is possible to visualize the phase difference between woofer and tweeter with REW?
if the answer is yes, how?

Hi all,

I had this idea on my mind to design amplifier that will have 2SK170 (or LSK170 or LS844 matched pair) used as LTP producing respectable THD performance while delivering nice sound.
For output stage I wanted to use IRF9240 and IRF240 MOSFETs.

Theoretically it should work.
But it does not want to for some reason.

I simulated LTP and VAS stages separately and they worked fine.
Adding bias transistor servo and output stage broke it for some reason. Maybe I need to tweak the bias?

Anyway, will be thankful for any help.
Attached is TINA-TI simulation file.

With great help from this community I changed the laser unit in the Marantz CD63SE and it works fine now mechanically. Now suddenly I have an issue with the RCA output connectors. It appears that the center post of an RCA male plug is not making good contact with the RCA output terminal in the CD player. I've tried several different RCA cables and once you get one to work, it works for a while but even a small touch will lose contact. I have tried contact cleaner and bending the external tabs on the jack so the ground is making good contact so it must be the center hot connection that is iffy. If you push the rca plug in one direction it will make contact and play but obviously the contact is not good without some lateral pressure. The rca terminals are housed in a plastic housing directly attached (soldered) to the main board so I either need to find a replacement or figure some other way to cure this problem. Any suggestions? Thanks if you can help.

Hello All,

I posted the below on Audio Karma and it was suggested I come to this site.

I recently picked one up (not working). Did not attempt to power it up. I can't find what fuses are supposed be in this. Assume there are all fast blow fuses.

I removed the top cover to take a look inside. Left channel side there was a 4a 250v fuse and right side was a 4a 32v fuse. The 32v fuse was blown. Are these the correct fuses for this unit? If not, what is correct?

Anyone have the service manual for this? Like I can read schematics...Not! I'm an electronics Newbie. Mechanical side is my forte. Thought this would be a good project for this old retiree.

I would appreciate guidance getting the Amp going. What to do/not do etc.

Considering its age, it is in nice cosmetic condition. SN 770882. Ground broken off the power cord so need to replace the cord.

Thanks much

Recently built a DIY speaker kit.....my 2nd after putting together a different one nearly a decade ago.....So far I'm not a huge fan of how it's voiced and how it sounds in my particular application. (I liked my Classix II better......) I've found measurements for this kit that confirmed my suspicions of what I was hearing.....
So I'm looking at altering/experimenting with the crossover, but I'm new to this, and learning about crossovers.... Been reading through some of the massive threads on these, and trying to understand the basics of how they work, etc.

So, I've drawn up the supplied crossover for this kit...... I can understand that that L2 and C3 are a filter for the woofer, basically...and that C1 and L1 do the same for the tweeter....and R1 is probably there to bring the tweeter down to the desired level... But I can't figure out the purpose of the 2nd capacitor in series after the first capacitor/inductor combo on the tweeter....What would this do? And the purpose of the R2 parallel resistor...I assume for impedance matching? Or do the 2nd capacitor and parallel resistor somehow work in combo? Or is there something else I'm not understanding?

Thanks for any insight!

-Nate

I am (trying) to build a PC88-ECC88 phono pre— I have gotten the bugger working and it measures and sounds fantastic….but…it is also oscillating and motorboating like crazy. Design is on a PCB and I used separate 100R CC grid stops for all 5 grids. Motorboating is obviously a PSU coupling issue but I cannot get the PC88s to stop squealing. I tried 470R CC grid stops with no luck so I must have a layout issue. Any tips on using high-gm tubes on PCBs?

Has anybody got T/S data for this vintage speaker?
I have 4 of them and thought I would give them a try.

I was lucky to get some AD1865N-K dacs and plan to build dual mono dac with it.

Did anyone do the same and can you please share the output circuit? I would prefer to go with passive I/V (resistor) stage. While it is a simple resistor between the current output end the ground for each channel using single chip, what is the best approach using two chips (dual mono)?

Is it possible at all to use passive resistor also for dual mono differential current output?

I just got this odd two channel SE amp for$50 thinking I’ll just use the transformers but I’ve never seen anything like it before. There are no names or model numbers and it came without tubes except a 5R4 rectifier. I can’t figure out the resistor array on top. Looks like DC heaters. Who has a clue?

Used matched pair of tubes for sale.Iv used this for about 6 months in my tjoeb cd player.I sale the player so dont need this anymore.Buyed by kunisch tube shop germany.Used about 6 hours pro week.There is no hum and no hiss.Verry good sounding tubes.Price would be 60 euro plus 8,90 shipping inside EU with track.Payment paypal for friends.

https://www.apexjr.com/Sockets.htm





https://www.apexjr.com/Sockets.htm

I'm working on a hybrid line stage with a tube voltage amplifier (6N6P in LTP) feeding a source follower output stage. The source follower will be cascoded and use a CCS load, with a B+ of around 250V.

Besides the higher cost, what are the pros and cons of using a SiC Mosfet for the source follower (and cascode)?

Hi everyone,

I have an Arcam Alpha 10 amp that on power up, displays a solid amber LED for around 20-30seconds then drops to the flashing red LED.

I've checked the main rails and the 5v/15v power supplies and they seem to up ok (I can measure them for a few seconds on power up), there are also no signs of DC voltage on the output of the amplifiers. I've also been round and checked all the fusible resistors but these are all ok....

I wondered if anyone had any experience of these and had any advice as to where else I can start looking?

TIA

I really do not understand their range of drivers so i must ask, which of their 6.5” driver has the best combo of midrange and woofer sound quality?

Hello,

I am designing my first set of speakers and I have questions about crossover.
I have designed this theoretical crossover with Xsim, difference between the loudest and the most quiet points in this graph is around 5db but that is mostly due to speaker curves as I understand.

1. I don't have access to driver measurement equipment and will use DSP EQ tuned by ear so is it really necessary to try to find a friend that has a studio and pro mic or this would do?
2. Is there a difference if I should solder L-pad before or after the highpass?
3. By manufacturer's datasheets my woofer would play up to 1,5 kHz and tweeter from 1,4 kHz up. Is 100 Hz enough to crossover in practice?
4. Can I trust FRD and ZMA graphs found online?

Drivers I have chosen so far:
Woofer: Tang Band W5-1138SMF
Tweeter: Dayton Audio Reference RST28F

Gents,
As the title states, I am looking for something to replace the now, seemingly unobtanium, SilentSwitcher. I liked those a lot!

I need to power 2 to 4 opamps, so very little power needed, but needs to be very COMPACT and high performance. Are there pcbs or kits available?

thanks!

Hi all,

Schematics is one-to-one from the application note for LS844 JFETS (those are dual 2SK170).
https://www.digikey.com/en/pdf/l/linear-integrated-systems/ls844-application-note

I was wondering what kind of distortion figures this amplifier produces so I simulated this in TINA TI.
Few models were missing so I had to search for those.
MJE15032 and MJE15033 transistors are not available and were substituted.
Attached are all sim files.

This is a comparison of Intermodulation Distortion (IMD) in 2.5" (70mm) drivers. This test will focus on the SB Acoustics SB65WBAC25-4, Tectonic TEBM54C30-8 and Wavecor FR070WA05. These are fun drivers to test and listen to, the absence of cone breakup where your ears are really sensitive (around 2k like from a 6" woofer) is pleasant to the ear.

I like all three drivers for different reasons. The SB acoustics has the most high frequency sparkle, the upper harmonics that come off of stringed instruments are accurately portrayed. SB acoustics is also the lowest price of the three. The SB has well engineered excursion as it kept up or outperformed the other drivers at 150hz while having a smaller cone area.

The Tectonic does very well in the midrange, the acoustics and ambiance of the recording room come through clear. The tectonic can also play louder than the other two with it's bigger 1.52" voice coil and higher sensitivity. However the tradeoff is less native bass response. The Tectonic projects high frequencies as advertised, I walked across my room while playing music with no discernable drop in the high frequencies.

The wavecor has a very low loss suspension and it can portray larger than life dynamics. The large impedence peak in my .5 liter test box boosts the efficiency from 105-215hz and drums and other instruments with fundamentals in this range sound excellent. This is interesting to me as many large woofers (6-10" for example) drop impedance in this 100-200hz range and sound rough. All three drivers can use some filtering or baffle step compensation, however if none is used the wavecor sounds the best to me as the native high frequency roll off blends well with the relative boost you see in the treble with baffle step.

I performed the 150hz-800hz IMD tests with the same measurement conditions as my other IMD tests (The microphone is on a stand 49"high with the base of the microphone 33" from the driver). But for the other tests since they contain higher frequencies I measured on-axis at 1meter away. All drivers were placed in a sealed enclosure of .5 liters.

Any feedback or drivers you would like to see?

I have put together a HV pulse circuit using a 6BK4C.
This is my first tube circuit, so just a beginner when it comes to tubes.
I want an understanding of the tube and how hard I can push this 6BK4,
I'm using it at 12kV, well under the maximum spec.

Does that fact allow me to raise the maximum current at all?

The spec sheets says, "Under Maximum ratings",
'DC plate Voltage' 27,000 Volts,
But then says 'Unregulated DC Supply Voltage' 60,000 Volts.
I don't understand the difference?

Then I see 'Average Plate Current' 1.6Ma, does that mean if I have a 50% duty cycle, I can go to 3.2ma during the conduction time?

The next spec is 'Plate Dissipation' 40 watts, Is that plate Voltage times plate current?

Meaning, 40 Watts / 12,000V = 3.33ma plate current?

Then at the bottom of the specsheet there is a note;
* series impedance should be used with cathode to limit cathode current under prolonged short-circuit conditions to under 450ma.
Confusing, when the maximum is 1.6ma!

I've attached a simplified circuit diagram, but it's not much more complicated.
My basic question, I'm pushing the plate current spec a little, how much can I get away with?
Thanks for the help, Mikek
The specsheet is here, https://www.rfwiz.com/6el4a-6bk4c-ge-vacuum-tube

Hello. I'm looking for a pair of the tweeters used in the GR Research XL-S Encore speakers. I have a pair of the XL-S Classic's that were designed by Danny Richie and sold by AV123/Onix, and I'm not quite satisfied with the sound. Would like to try to upgrade them to the XL-S Encore, if anyone has a pair lying around let me know! Thank you 🙂

Hi All. I am working on a very large metal sculpture with the center focus of a 3D copper head of Freda Kahlo. I want to make the head with a steel core structure with metal rod bent to match the “slices” if her head in what would become 3” layers, top to bottom.

I need help from someone to 3D model her head from a number of photographs, then pull out the individual slices which I can blow up and bend the rod to match.

I’ll the weld the rods to the metal infrastructure and cover the rod structure with copper.

Does this make sense? Thanks guys.

Due to grossly overstocking I`m able to offer a number of these critters, namely the 2SA1349GR/BL-2SC3381GR/BL and 2SJ109GR/BL/V-2SK389GR/BL/V for sale. As I`m a sticker for symmetry, they will normally only be offered in pairs, however exceptions may be made where I don`t have matching numbers. Please apply for pricing structure.

Regards
Roar Malmin

Hi all,
I've built two of Ivan's speaker kits (IPL acoustics) and was about to buy a third when I found out that Ivan has retired. The kits were amazing. My £300 M3TLm kit (I made the boxes from mdf and veneered them) sound and look superb. I now want to build another pair.
I can source the drivers and make the boxes but I'm struggling with the crossover (the kit came with all the crossover bits and some great instructions).
The speakers are transmission line, use hivi drivers (ribbon tweeter and woofer) and a biwired terminal. I've attached (I hope) the crossover diagram.
I'm not sure about the inductors.... can I buy a ready assembled crossover that would work OK? The speakers are two way. What size inductor would i need?
Assistance would be appreciated! Thanks.

HI,
where is daphile technical support on the web? Is there a dedicated forum?

How can I set up the touch screen display on Daphile?

Thank you
wide

I have a Helix MKII amplifier stuck in protect, was playing fine when I got it but only for 10 or so minutes at low volumes before going into protect and staying there. Bought it with the knowledge of it being stuck in protect before so knew I was going to have to mess with it. Has the orange “short protection” LED.

Input voltage 13.6v (the 5.1v on pin 16 is present as soon as I attach the remote, but within a second it drops to 0)


3525
1) GND
2) 0
3) 0
4) 0
5) 0
6) 0
7) 0
8) 0.520
9) 0.010
10) 0
11) 0
12) GND
13) 0.399
14) 0
15) 0.399
16) 0


LM339 (there is two on this amp, both by each other) Left/towards power terminals
1) 0.006
2) 2.038
3) 10
4) 0.007
5) 7.14
6) 7.14
7) 8.58
8) 7.35
9) 0.985
10) 0.688
11) 7.14
12) 0.001
13) 10
14) 0.078

LM339 Right/towards speaker terminals.
1) 8.66
2) 8.66
3) 10
4) 7.14
5) 9.68
6) 7.14
7) 9.67
8) 8.66
9) 7.14
10) 7.14
11) 8.66
12) 0.001
13) 0.006
14) 0.047

Has anybody heard Monolith Magnetics OP transformers. They're located in Belgium. Can't seem to find much in reviews on the web.

Hi there!

Got an option to pick up a pair of Faital 18XL1500 cheaply with the goal of building a compact, single driver, reflex sub for PA use.
In that regard I got two question that I hope you could help me with 🙂

1) With a volume of 285L and a tune of 30hz i get a F3 of 28 which is plenty low for what I need.
However, modelled cone excursion at 1kw exceeds xmax with 1.5mm at 40hz. Is that amount critical to the longevity?
Going smaller in enclosure volume or increasing the tune gets me below xmax but makes the port length too long to build.
Is there a way around this?

2) My plan was to build a onken style enclosure with a total of 6 tall aspect slot ports along the sides. The baffle will be recessed for stiffness and protection of the driver, creating a sort of 'enclosure within a shell' (I have made a crude sketch of the design below from a top down view)
Where should I measure the ports from?
And is there a critical dimension at the corner that I need to be aware of?

I hope all that makes sense.
Cheers.

I'm currently working of a Bottlehead Kaiju 300B speaker amp. I'm planning on upgrading the caps when I install the DC filimant upgrade later on down the road. For right now I'm looking for 300B suggestion to try out on the Kaiju. I already own a quite a few different pairs of the 5670 input tubes so I'm set on that front.

I am currently looking at getting a set of Mesh/Perforated Chines tubes. Like the Linlai 300B-N, Cossor 300B, Psyvane 300B-NSen and the Linlain 300B-T2. I've looked at the EML tubes but they all have a higher amp level than is recommend for the Kaiju. Anybody have experience with the Chinese mesh tubes? If so how did they sound/how reliable are they?

I'm also looking at getting a pair of Linlai E-300B, since I love the Linlai E-6SN7, or the GL 300B.

I'm willing to spend around $1000, in total, for the tubes so I'm also open to any suggestions

Hi there.

I got a used wooden amp box cheap, 7USD. It has a TDA2030a for the bass and it worked in a test when I moved cables, the main output is burnt, shorted speakers were connected.

I found it interesting because it has a 4th order band-pass in the box. I hadn't seen it before, but I hadn't seen too much so maybe this is common. The back of the speaker in the photo is isolated with the sealed part. I couldn't find similar devices it with image searches nor with the model in the label.

The transformer gets hot, wondering if it's because something's shorted in the board. I'll test in a few days.

I think I'll try using a TDA7850 for 2 full range drivers and 2 tweeters and a Tpa3118 for the speaker that came in the box. I watched this review for the TDA7850 and by reading the datasheet I think that by pulling less watts and using 8ohm it could sound good.

I could build another front panel and reuse the glass if I put a Raspberry PI I have around, with display.



Thoughts welcome.

Before I make prototypes, which resistive vent you expect to be best.

Speaker will be used close to the wall. Fullrange driver crossed to the woofer at 350Hz.
CNC machined, stacked plywood construction.

All prototypes will use Acoustic Thinsulate 7.7 kg/m3 inside.
Prototype C will be using wool felt sheet , 20 mm, 230 kg/m3 covering round holes from the inside.
The rest will use wool felt sheet 2 mm thick, 230 kg/m3 covering the vent hole.