Good day all,

I'm 1 of 5 that is responsible for designing a class d amps for bass frequencies. we got everything to work except the power stage. The output of full bridge configuration outputs a small square wave (mV) from a 5 volts input.

Gate driver: HIP4081a powered by 12 volts
Bootstrap: 10uF and 1N5817
Mosfets: IRFB4019 powered by 24 volts.

Can anyone please assist us?

Missing rail at the outputs, what would some possible solutions be. This is the older bd model. It came in with a burnt power supply and driver card. Repaired all of that now missing rail voltage at the outputs.
The regulators are all Correct. The capacitors are all brand new as well.

Hi!

Several boxes of new old stock arrived with me today. I have 64 TC9FD18 drivers to work with. What should I do? 🙂

Any thoughts on adding a dome midrange (monopole) to a 3 way OB? I'm currently running an open back planar tweeter, 8" midrange and 2 12" woofers per side (all active). I impulse bought an amplifier off of the 'Bay a few days ago and I'm trying to figure out my next move. ALL opinions and experiences are welcome!

Hi guys.

I am in the process of building our new house and the home theater will be be integrated in the living room. Because of the open plan layout the placement of the subwoofers is set under the tv, up against the wall.

There are 8 JBL CS1214 sealed subwoofers in total, driven by an inuke 6k. Just for reference I have attached a sample close mic response (ignore SPL).

To hide them in the room I would like to build a very solid cabinet under the tv, up against the wall and place 2 subwoofers in each 5-boundaries space, with vertical wood slats at the front.

How do I go to calculate the gain for multiple subs + boundary gain when there is 4 identical pairs with multiple boundaries per pair? Do you calculate the first pair with the spatial loading gain and then add 6db or 3db per doubling? Or do you calculate doubling (18db) plus 30db boundary gain? Is this considered co-location (6db per doubling) or not (3db per doubling)?

Looking forward to learning a few things! 😎

For sale is Naim CDX olive player with new laser head assembly and a refurbished mechanism. Player is in very good condition with no visible imperfections except lower corner nick on the bottom of the player. You can see it when you turn the player upside down. CDX is/was a part of Naim reference line of players and is still a great sounding machine.At times I prefer it to CDX2. I can provide a spare laser part guaranteed to work for additional $40. I don't have an original box. The player will come with remote, cd puck and a transport screw also a burndy plug of course. Condition rating for age since I can't see any imperfections (except that corner when I turn the player upside down )-$950

I picked up this amp and got it home and it wouldnt turn on. So I opened it up and see that one cap is blow and the 2 large ones look to be bulging. Need some help on where to start. I took a couple pics.

I've got a Clarion apa 4400g with powerguard. Cool amp, rated at 100w x 4 @ 4 ohm.

I repaired the power supply section, it had a broken trace at the remote terminal, and voila, 3 of the 4 channels sprang to life. But... The channel 3,. That one, decided not to spring back to life.

Signal goes from the input to the op amp boards that have the gain and filters, and mono stereo selector. From there I can follow the signal around to the last op amp on the main board, and them to the output section. I can trace both left and right signals to the stk350 voltage Amplifier, but channel 3 doesn't get there. Just before going into pin 14, it gets all messed up at the resistor marked with an arrow. Color bands indicated a 520 ohm 5% tolerance resistor. It's resistance was off, read 870ohm or so. So I pulled it. And I replaced it with a 475 and 33ohm resistor in series. The signal is distorting and not coming out of the replacement resistor. Why would the signal get stuck there

A Rockford T1500-1bd board number 1325-52759-05 (from 2007) doesn't start up. I found two burned resistors R6 and R1022 near the power supply, see pictures.

What are the values of these resistors..? Any schematics around..?

I picked some amps up at a garage sale and this was one of them. The amp wont power up I know I have 12v coming into it. It was really dirty inside.

I have build my self a new remote controlled test switch for A/B comparison of amps and sources.

I had such a switch for many years, to do tests while modifying all kind of audio gear. I dislike just doing modifications and have no way to make (more or less) objective listening tests.
So I put one reverence or un-modified part on one side and the "tuned" one on the other. Then I switch between them without any delay and listen.
If you have to change wires, this is not as effective as just turn a switch to really do A/B testing.

Because today many amps are bridged, I decided to build a new switch unit, also more comfortable and universal than the old one, that used a wired remote switch.

One side switches two amps to one pair of speakers or with one amp between two sets of speakers.
Because relay contacts wear out when switched under load, they are doubled. Not elegant, but a good way to keep resistance down.

The other side can be used to compare sources like CD players or DAC´s, or just to match levels while comparing A/B on the other side.

On the RCA side the ground is switched with the signal to prevent ground noise from different sources.

By using cheap offers from eBay and AliExpress I was able to realize this for roughly 30 US$.

Parts are:

Remote control 12V
4-way relay board
8-way relay board
6 double speaker binding posts
6 RCA sockets
1.5 A voltage regulator
some wires
a used case


I will just post pictures from single parts to finished unit. If you work very pedantic, like me, be prepared to spent a whole day on it. All these wires are really time consuming.

PS still have to add some LED to show the state of the switchers.

I built these last Fall. Looking to give them away to a local enthusiast.

Here is the design...

http://www.diyaudio.com/forums/full-range/226767-wibaq-tabaq-design-betsy-k.html

They are housed in unfinished maple plywood.

You come and get them for free in Saint Paul, MN USA.

Hello!
I'm trying to fix a vintage SS guitar amp that has a very bad distorsion.
It's a try and guess so i'm replacing transistors... but some are hard to find, would someone know about good replacements ?

MPSA55 (only available at one store with heavy shipping cost)
MPSU06 (this one is fried so i need a new one...)
BD507
SSC PLZ 417 (looks like a diode, cannot find anything related?)
BF315
BC209B


thanks !

Good Morning

Anyone have or know where I can get a BD output card for Rockford T2500BD.
I just bought one by parts and I need it. You can write to my email albis.calderon@gmail.com to contact us

Hi


The replacement SF135 Ultralinear output transformer I ordered from Hammond has arrived. I fitted in this transformer and put in all new tubes, Two 12AT7, Four 12AX7 and Four 6L6GC. I turned ON the amp and set the bias. The amp is working but when I turn the master volume above 4, it gives out a whistling sound and the tone becomes very sharp (high frequency). As I increase the volume further, the whistling gets louder and deafening. I then put in another output transformer from another SF135 ultralinear twin reverb, and this is transformer is original. I set the master volume to maximum and there is no problem. I wonder what is happenning as this 1750WR Hammond is suppose to be an exact replacement for this Fender Output Transformer No:013691.
I am sure all the wires for the plates and screens are correctly fitted. The secondary, green/yellow is fitted to the output from the board, the black to speaker ground (chasis) and the green to Ext speaker terminal. What could be the problem. Attached the pdf for the transformer.


Thanks

Hi,
I am currently designing a guitar preamp and before my tonestack I want to put a paralleled 12ax7 (shared plate resistor, shared cathode resistor).

I want to draw my load line for this stage but it seems impossible to find the datasheet for parallel 12ax7. If anybody has it, I would love to see it.

I've checked on many forum and did not find the information I was looking for.
I know that if I 1/2 my resistors the stage would behave like a single triode, but that's not what I want to know, I just want to design and draw my loadline...

Any help would be appreciated!

Thank you

WTB

Dayton Audio IB385-8 15"

Thanks

I've been toying with the idea to make active speakers with DSP for a while, but it always seemed too expensive - either using MiniDSP's with chinese class D amps, or using existing plate amps with DSP, it always turned out to cost at least 300 euros per speaker just for amplification and DSP, before even starting to look at drivers and cabinet building.

Today I stumbled on this:
Aktivlautsprecher | Lautsprecher- Bausatze | Hobbyhifiladen

These use Wondom TPA230 / 250 boards - basically class D amplifier boards based on the TPA3116
(that my current DIY amp is based on as well!)
AND include DSP - and these Wondoms just cost around 45 euros!

It seems I have found my platform to start tinkering with DSP on a budget..!

Sure it means having to learn Sigmastudio, but as I'm clueless about analog crossover design as well, learning this seems a nice doable hobby project to me as I'm better with code than I am with analog electronics 🙂

Has any of you already played around with these Sure / Wondom DSP thingies?

Hi guys,

I need some help for my setup. I built by myself pre, amp and a network player but I never built a speaker before and I'm not good when it comes to wood work. For this reason, being my first try I would like to use some kind of pre-made kit.

I am looking at a full range bookshelf speaker set that can offer some good overall sounds, with clear mids and solid bass. I listen literally all kind of music.

Speakers will be installed on 50cm stands and replace my cheap Mission LX-2 on this setup:

ESS9023 based DAC
Kuartlotron pre
TPA3251 amp

My room layout is attached.


Any nice idea?

Cheers!

Hello,

I decided to refresh my old the speakers, the new dumping, the wiring capacitors ... But when I pulled out the crossover I was confused by the design.

I would be grateful if you would take a look at the photos and the drawing I made and tell your opinion if everything is all right before I buy the capacitors. I measured and wrote the values of the coils and resistors in the drawing. Maybe I can put in better resistors so please advice.
It confuses me that the capacitors 2.2 and 1.5 are in the series, it also seems to me that the bass does not have a capacitor, I also do not understand the point of soldering the negative pole wire before the coil of the twitter speakers.

I don't have much knowledge in electronics, especially I don't know the logic of crossover design and I don't know if anyone has ever worked on that crossover before.

The speakers are Pilot V-3 (German speakers from the early 80's)
I don't want to change the characteristics, I just want to improve them.
I will use Mundorf mcap evo oil Capacitore, and keep the ferrite coil on the bass.

All tips and ideas are welcome

I consider this part of the DIY Audio forums as a research center run or at least driving by Nelson and his wonderful electronics proposals.
I noticed that most of it are based on "non obtainable" or old new stock of transistors.
Why that ? Can't we find in the actual productions some interesting components ?
For instance, things like this :
CG2H40xx & CG2H30xx GaN HEMTs - Wolfspeed / Cree | Mouser France

I have no idea if these could even be placed into a musically interesting amp, but here is the idea.

The Microsoft "data streamer" app seems to have been developed within the last year or so. It provides a very easy method of reading serial data from an Arduino/PIC/Atmel.

If you have Office 365 you can find it by opening an Office application:
File->Options->Add-ins-> Manage COM Add-Ins

If the program isn't listed, you can download it from MSFT.

There are some youtube videos demonstrating use of the add-in

Hi!
Do you think that the Satori TW29RN-B can benefit from a super tweeter?
If the answer is yes please let me know some good examples.

Thank you!

So I'm looking at another project and thinking of buying a chassis that has some holes pre-drilled - IEC, Volume, Power. The only missing holes are RCA and headphone jack. RCA is easy. 4mm back panels. Since this chassis has a 8mm front panel and my headphone jack won't go that deep I need to make the jack recessed. The plan is to first drill a hole that works for the size of the jack 8mm deep using my drill press. Then use a separate bit that is larger and go about 4mm deep. What type of bit is used to do the 2nd hole? My guess is a reamer. Or is there a better bit for this?



Thanks,
Mull3t

Hi, greetings all.

Looking to learn a lot here.

Currently listening to vinyl on :

Rega P3 2016, with a whole host of modifications raring to go, waiting on a camera to take some footage and measurements using the KAB Speedstrobe kit.
Hana SL cartridge already installed.

The Beast all valve phono preamp is on it’s way!

Primaluna valve preamp, 1973 NOS AU7s matched from Watford Valves rolled in and it sweetened the sound right up!

VTL ST 85 power amp, ran KT88s for 18 months, in for repair tomorrow as first left tube failure and impossible to bias!

AR 210 monoblocks arriving in the next few days as an upgrade.

Q Accoustic Concept 500 floor speakers.

I have a Sony PS-X70 on my bench that isn't doing the one thing every turntable needs to do -- turn! When either Start or Auto Start are pressed, there is no movement of the platter. Nada.



After some work on the power supply board, all of the PS voltages to the main board are correct. Working backwards from the motor, it appears that the issue starts at IC3, prior to the gain adjustment for the Hall Sensors and the motor drive circuit. I should be getting around 1.8V at pin 1, but instead it shows zero. When I bypass IC3 and apply 1.5V DC from an external source, the platter turns. I'm also seeing zero at Pin 3 and at the emitter of Q5. Given these measurements, I'm trying to understand how the circuit is supposed to function to send the correct voltages to pins 2 and 3 of IC3. Is it via Q2, Q3, Q4, and Q5? Or through IC1?

Schematic — imgbb.com

I am planning to produce new stabilizers or the Sony players using the "Fixed Pickup Mechanism"
The Sony CDP-X5000, Sony SCD-777ES and Sony SCD-1 are some famous players
using this mechanism.
A short movie of the working prototype can be seen here:

https://www.youtube.com/watch?v=Zda77-xck1E

Anyone interested in them, thus I could start to produce a first batch...

All the best,
Salar

Hi!
I want to build the Phy-HP open baffle with H30LB15 and twin TW-37 that is based on the links below.

openbaffle

twinplate

But Twin TW-37 plate failed to indicate the screw mounting holes for both twin TW-37 and H30LB15.

Anyone can advice??

Thanks!

Hi all,

I've got a class D amplifier that runs in either single ended or bridged configurations, and I'm working to figure out how much decoupling capacitors I need.

The power supply has two rails, -60, gnd, and +60.

There are multiple class D modules on these rails, and they are running at +-15V max signal output when in single ended mode.

In bridged mode, they are running at the full voltage for 70V commercial distributed audio output.

I'm trying to wrap my head around how much decoupling capacitance is needed for my application.

Is it really just a matter of target THD since I'm barely pumping the rails in single ended mode? or is there a safety issue with skimping on decoupling capacitors?

Thanks in advance,
bob

well I want to have home sub-woofer that has 12 inch and over 1200w at 4ohm load what could you suggest me to have or is there something could fit to be best in home use?

Monster power strip hts 1000mk2
All caps.
Turn it on get a buzzing noise , something internally needs repaired .
Need a cheap soldier tool but still do not have one [emoji3516]
Any help ?
Thanks
Not sure we’re in forums this belongs , any mods can move this ..

hey there,

Trying to understand how to bypass the bad HPF-OFF-LPF switch on a Sony XM-1502SX. I want to fix the board so the filter is in the OFF position. I want to think I would jump the three middle pins? I have attached a page from the service manual and the switch is on the bottom left by #4. There are 2 sets of 5 pins and not sure which ones to jump to get full range.

thanks for your time

Hi Guys

I’m looking to construct a low pass filter. Having done some research I can see it would consist of a resistor, in series and a capacitor in parallel.

Would it be possible to change the order that is parallel the capacitor first and then add the series resister. I was actually looking to use the input impedance of the amplifier thereby only using a parallel capacitor.

Would this arrangement achieve the same result.

It’s quite clear from the research that Ive done for a high pass filter that the capacitor is in series and the resistor (amplifier impedance is in parallel) and that works ok.

Many thanks

I'm about to start the process of drilling into an anodized aluminum chassis purchased via Par-Metal and I'm looking for tips on the dos and donts with this particular chassis.

A few thoughts on the process:

• I'll be using a 10" bench top drill press for drilling. So at least it'll be easier to make precision holes.

• I've bought an automatic center punch for initial hole drilling.

• When doing design phase of this project, I used AutoCAD for drawings. I plan on printing out drawings at 1:1 scale and then applying to chassis. Any tips or tricks for this?

• I've heard it's best to drill a pilot hole first - at least for the larger holes.

• I've also bought cutting fluid to keep bits in shape and heat down.

• I got some scrap aluminum to practice feed and speed on. RPM on drill press is adjustable from 530 to 3100. I've heard RPM for aluminum would be at slowest setting.

• For the larger holes e.g. Neutrik panel mount holes I was going to start with a smaller hole and use a stepped bit to get to close to the final ≈1" holes.

Some questions:

When drilling the holes should I do from within chassis to keep a cleaner look? Not sure if this makes sense or not.

Am I missing anything?

Thanks,
Mull3t

My brother suggested I join this forum about very technical tube stuff. I'm new to this forum. I never heard of anyone talk much on EL156 since it's quite popular in Japanese DIY Audio field.

I read its specification, it can run 450V for class A and class AB up to 800V.

It's a pentode, but can be run in triode for 500V. I see someone claimed a pair of these in PP capable for 150W!

Therefore, which way you prefer class A pentode or triode, or high power in class AB with much high operating voltage??

Hi,

The Electronics instructor where I teach wants to run a class to build a tube amp and is asking for my assistance. I may have planted the idea in his head, but cant be sure 🙄. In any event, we've come up with three options for an AB1 amp; bargain, mid priced, and full tube Williamson circuit amp. In tallying up the cost of parts, just the expensive ones, prices are about $250, $330, or $400. At least I think that is what my notes say. Most of the cost difference is in the transformers.

My question is, for an introductory electronics class is one a better option than another? People taking this class may not have any experience with electronics, or may be fairly well versed. I don't know the cost of the class at this point, but we would be providing the parts and there is a very noticeable difference in the "kit" prices. We'd like a good turnout so the lower price is attractive. We also want something that sounds respectable and provides about 8 to 10 watts. Any suggestions for which way to go?

We talked about building the PS on it's own chassis, and the low and high priced alternatives on their own chassis for comparison purposes. That sounds like a good experiment, doesn't it?

Dual Power Amplifier Board PCB Toshiba 2SC5200 2SA1943 400W Mono High Power AMP

I translated this board to ltspice and I am getting 11% thd on it. Can someone confirm this for me. My asc file is attached. I am new to using ltspice so although I have checked my settings several times, I may be doing something wrong.

Hello,

I'm thinking about making a DIY subwoofer similar to Klipsch R12.

Is there a payable fitting class D amp with crossover network and phase regulation?
I found nice amp boards based on IRS2092 but no signal manipulation moduls.

Hello people.

I got given a dead Kenwood KAF-3030R for free.

The unit has no standby power or anything so I've suspected its a standby board issue. It had the mains cable half cut, damaged, the natural wire cut only. Not sure if that created the problem or was damaged afterwards.

So far I have cut the mains lead down and soldered it to the pins, it gets the voltage to it. I downloaded the schematics from Hifi Engine, tried the hold source direct and press power button to no avail. I checked the voltage before the relay on the standby board which should be 13v yet only 2.6v. This makes me think its a problem before the relay. I checked the resistors, measured in tolerances, pulled out the diodes, measured good both ways. This makes me think its the standby transformer being faulty. I'm presuming the ceramic caps are fine.

I have a working Kenwood kaf-1030 yet its not remote controlled so no standby board to swap over.

I have spare standby transformers from other equipment and wondered if I could try them? I'm guessing not.
It has a microcontroller to control the input but Im guessing it's not a problem with that?

I have reflowed all suspect joints and all joints in standby board and switch board. Swapped the electrolytic 470uF cap for a working one. All fuses had continuity.

Any advice will be greatly appreciated indeed, as always, thanks for reading.

I've got a Sony STR-DN1060 which blew one of the FL channel transistors the other week. I've replaced the pair and the matched double ceramic resistor. Put it back together and I'm still getting a protector error after about 10s.

I have the schematics for it. I've stripped it back down (repeatedly) and checked the resistances across the resitors in the current detector circuit on that channel (R1700-R1719), all look ok. I've checked the fuses (all OK), and D1700 and 1701, also check OK.

Any ideas for where to go next please?

I recently got this amplifier which seems in original condition. Serial# 36, so probably quite old and appears to have been well used.
It plays very silent but there are a couple of small issues: a "thud" at startup
not so loud to worry for the speakers though; I wonder if this is normal?
Second issue is that after shutting down it continues to deliver distorted
sound for some 10/15 seconds.
Bias seems ok at approx. 55 celsius on both heat sinks (average temperature of 26 in the room).
Maybe time to change main caps and/or check anything else?

Given M ( ms ) and other T / S parameters
With driver in hand ..
Can M ( md ) be calculated ?

I see a few reviewers that seem to think this company's products are
a great value at double the price. Sonics akin or better than Pass.
Anyone tried them?

Hi,
I'm helping a friend with his broken IA100, he told me that it suddenly wouldn't adjust the volume.
I'v done som quick testing, one channel is running low and the other is running on max volume it seems.
I hooked up an external pre amp to main in and that worked fine.
I see that it uses a software controlled LM1972m chip for volume adjustment, can it be a software error or is the chip it self at fault. haven't found any other faulty parts yet.
I'm not that familiar with chip testing, how can i measure the chip?

PCB version: EM1070 rev.9

Also, does anybody have the service manual? Or just the schematic of the pre amp part?

edit: found schematics for IA60 looks like it uses the same PCB.

Also, R139 and R140 seems to run very hot, is that normal in this amp?

Hi All.

I've been trying to wrap my head around Hornresp for a little while now in order to design a full size 30HZ horn, but I am having difficulty reading my results. I would like to build two horns for "stereo". These horns will be crossed over to a two way horn loaded speaker at 80-100HZ. I will probably use a La Scala bass bin or similar with a single large horn for the high frequencies.

I know that this will make for a very large horn, but I do have the space for it, and I would like to use the concrete walls and floor of a large space for two of the four walls of the horn. This system will be used for listening to music, not for PA, so sound quality is more important than SPL.

I have attached a couple of photos of the Hornresp simulation for your consideration, and I have a few questions.

1. If I use the throat area, the mouth area and the horns length as primary design criteria and either ignore or roughly approximate the flare rate, would that have a large impact on the horn's sound quality?

2. I have a pair of Alpine SDR 1222D at hand, and the sim is for these speakers, but I will build the throat/back chamber so that it will be easy to swap out drivers or change the sealed back chamber size. I have a couple of pro amps that have plenty of power for these speakers. Are these 12 inch Alpine Type R speakers a good choice?

3. If I were to build the horns with at least a rough approximation of the exponential curve, where do I get the required measurements? Am I missing something in Hornresp that shows these measurements other than the schematic?

Sorry if these are noob questions, but that would be a good description of my relationship with Hornresp. Any assistance/advice that you can provide would be much appreciated.

As promised earlier in the Semisouth GB, we shall offer 30 quads of curve traced matched 2SJ74BLs to J2 builders.
These are from a matching pool of 1000+ devices, and are curve traced using our own equipment under controlled temperature.
They have Idss between 6.4 and 7.4mA, optimum for the J2 input stage running at 3~4mA bias.

A typical quad set is as follows.
First number is Idss (mA), second number Yfs (mS).

6.42 36.73
6.42 36.77
6.42 36.87
6.42 36.98

Both Idss and Yfs are tightly matched, as can be seen.


The price for each quad set is 600 HKD including Paypal fees and postage by registered air mail worldwide.
The GB is limited to 30 quads, and to one quad per person unless there are surplus at the end.
There will be NO waiting list to avoid dispute.

We shall call for Payment some time in December.
You will receive payment instructions by PM via DIYA when ready.


Thank you for your interest,
Patrick

Suppose we have an active (not passive nor transformer based), buffered, variable audio balanced XLR output. If the answer potentially changes for SS or tube circuit, please explain.

I propose pin 2 to drive a sub amp with 12k input Z, simultaneously while pin 3 drives a main amp with almost certainly higher input Z (estimate 30k to 100k).

Pin 1 ground shorts to amp 1 and 2 input grounds. Let's presume the output has enough current to properly drive each load. I realize pin 3 is inverted, easily fixed by inverting speaker cable polarity. Sub amp volume fixes sensitivity differences.

Tx!

Edit: The amp is now sold.

Hi all,

It’s time to part with my Neurochrome flagship amplifier build. This no-holds-barred setup employs two Neurochrome Modulus 686 modules in a dual mono configuration. These are Class AB amplifiers specced to provide 360 wpc into 4 ohms with a vanishingly low THD+N of 0.00025%.

Some build notes below before the Bill of Materials and asking price :

1.) Power Supply
Not one, but *two* Power 686 modules provide the DC, backed by a massively oversized 1kVA toroidal transformer by Antek. This transformer has two 25V secondaries with a shield in the middle, making a true dual-mono configuration.

2.) Power Inlet
Neurochrome's Intelligent Soft Start was added to limit inrush current and provide a variety of switching options. Currently the IEC inlet's toggle switch is connected. I will include a trigger jack in the box that you can add if you wish.

3.) Power Output
The amp's power is tapped through Furutech's FT-867 binding posts (connected using their recommended FT-210 pure copper disconnect terminals). Unlike all-metal binding posts that carry a lot of conducting mass, this model uses a single OCC wire conductor wound around a ceramic+nylon+fiberglass housing. The minimal conducting mass allows the post to be electrically and sonically transparent.

4.) Signal Input
The amp's signal comes in over 23 awg UPOCC Silver wire by Neotech via Neutrik XLR connectors. I do have a pair of Furutech XLR inlets (FT-786) that can be included at cost ($80).

5.) Chassis
Everything is assembled into Modushop's 4U Deluxe Chassis - their top of the line offering, with Universal Mounting System holes for easy repurposing or expansion in the future. Since the amp does not use UMS, its mounting holes were CNC milled into the heat sink using Neurochrome's provided template.

NOTE: The rear panel came pre-milled from Modushop, and while the Furutech binding posts fit perfectly, their teardrop-shaped barrels bump into each other when twisting. You will need a strong twist to move past the interference, which is a one time exercise if you use spades, and a non-issue if you use bananas.

6.) Module Construction
The Neurochrome Modules were purchased fully populated, because Tom puts his boards through a complex wash cycle after soldering to rid them of residual flux, then tests them. He no longer offers fully populated versions of either the Power 686 or the ISS.

7.) Heat
The heat generated is minimal, even when playing at moderate volumes. The heat sinks remain cool to the touch.

8.) Sound Quality
The sound quality is really something to marvel at. The impetus for this build was to compete against my friend's Gryphon Diablo 300 at a fraction of the cost. Comparing them head to head, it is hard to tell who comes out ahead as they are very very close.

9.) Age
The build was completed in fall of 2019 and the amplifier has about 300 hours on it since then, meaning it is only just breaking in.

10.) Bill Of Materials
The Bill Of Materials is as follows:

2x Neurochrome Modulus 686 - $499 x2 = $998
2x Neurochrome Power 686 - $249 x2 = $498
1x Neurochrome Intelligent Soft Start (ISS) = $249
1x Antek AN-10425 1000 VA Transformer = $119
2x Furutech FT-876 Binding Posts - $75 x2 = $150
1x Deluxe 4U Modushop chassis w/ Anti Vibration feet = $355
2x Neutrik NC3FD XLR Sockets - $6 x2 = $12
1x Schurter IEC Inlet = $15
3 ft Neotech UPOCC Silver Solid Core 23 AWG - $11 x3 = $33

Total Bill of Materials = $2429 without shipping of components or assembly

* * *

I am asking SOLD + PayPal and Shipping as an adoption fee. The unit is in San Francisco with me.


Thank you!

Hey all,

I'm new to this forum and also new to car audio. I am still learning as much as I can.

I am building a sound system in my 2015 Harley Street Glide. I am running:

2- 6.5 inch speakers in the fairing - wired directly to the Sony AX7000 deck
4- 6x9 Polk Audio (4-ohms each) wired in series/parallel to:
Soundstream PN4.1000D 1000W 4-channel Amp with a 4 ohm rating of 140w x 4 channel

I was able to get everything working properly by wiring the 4 6x9 speakers in series/parallel, similar to the image attached:


I am happy with the sound, but I want more highs. To do this, I ordered 4 4-ohm super tweeters (DS18 PRO-TW220) at 225W RMS.

I ran them similar to the 6x9 speakers in series/parallel (since they are all 4 ohm resistance) to the "front" portion of the amp. The "rear" portion of the amp is running the 6x9 speakers. However, I am not getting any sound at all. The 4 tweeters come with capacitors built in. So, I was thinking about tapping into the wires for the 6x9 speakers to run the tweeters, but how would I do that without affecting the impedance? Where would I connect the positive and negatives to exactly?

Again, I'm brand new to all of this and refuse to pay someone to do this as I want to learn myself. Thanks.

Would someone be willing to recommend me an inexpensive isolation transformer for ground isolation / safety? I am putting together my first full-scale DIY amplifier building bench and I am taking all of the necessary safety precautions.

I have looked into several isolation transformers, but it seems that inevitably, each one has some fatal flaw (no pun intended), whether that be no true ground isolation, grounded neutral, etc. Any recommendations would be appreciated, thanks 🙂

I am looking through some mods for 6505+.

It seems mods for that amp are well documented and reposted. Most of them are clearly explained, as far as the reason for them.

Can somebody explain to me what this suggestion would do, theoretically?

Short R27 and C15. The Soldano SLO100 and high-gain Marshalls just use a 68k grid stop and don’t worry about the rest.
Increase R2 to 220K

Click to expand...

Here is the link to the schematic.

https://www.thetubestore.com/lib/thetubestore/schematics/Peavey/Peavey-5150-II-Schematic.pdf

Good Morning,

I have a 12B4 preamp that works great, except when my TV is connected via RCA and turned on. I end up with something that sounds like a 120hz hum. Is this a grounding situation? I presume it has something to do with the switching PSU on the TV.

The hum remains no matter what source is selected.

I had considered running optical from the TV to a DAC to the preamp. It's not out of the question but I really don't want to lose analog volume control from the TV.

Thank you!

Evan

Hello all! I am a sound man in progress, learning from mistakes and lots of hours reading this forum.

I DJ and set up sound equipment for social country western dances at various locations near the university I attend. Lately I have been having a terrible time with sibilance in my music and I simply don't have enough experience to know what I'm doing wrong. I have done a fair amount of googling, but most of the advice has to do with mixing live vocals or creating mixes in a program.

I'll list the specifications for the sound system at the bottom of my post, however here is the general set up. The dances are in a basketball gym. Music purchased from itunes is played from a laptop at 70% volume and routed to the mixer through the stereo RCA in jacks. I usually set the channel fader about 3/4 of the way up, a little below unity. The main fader is about 1/3 up. L and R audio is then sent to the two powered speakers set 40 feet apart using the XLR out on the mixer. And that it! There's no real mixing going on. The problem I am having is that I have started to have some painful sibilance.

I have tried turning down the highs, but that has only made the lyrics muddy. I turned up the laptop volume until the VU lights are hitting right where they should, and then raised the channel volume fader and dropped the main fader. That helped some, but it was still bad and the music was muddy.

I am almost certain it is caused by operator error and not the equipment because I have used this exact same set up for previous dances in the same location and did not have a problem. The music format may be contributing, however I have used the same music files before with no issue.

What are common causes of sibilance when playing professionally produced music over a PA? Any advice anyone has would be appreciated. Thank you for helping a noob out!

Equipment used:
Yamaha MG12XU mixer
2 Peavey PVXp15-DSP 800W 15" Powered Speakers
Lenovo laptop playing music from itunes

FS: Satori MW13P-4 5” midrange / midwoofers (Pair)

Price: $175 shipped to the continental US.

Condition: New in Box

Photos:

Can someone clue me in on what to call these RCA jacks in a search term. I’m having a devil of a time finding them online. I need to buy some.

Thanks,

David

So, my band has a gig this Saturday and our lead guitarist's head just suddenly stopped working yesterday. It's a Marshall Valvestate 100v 8100. We had a show last night and after everything was set up and he pushed the power button it flickered on then died. You can imagine my panic. Luckily the band before us was nice enough to let us use their setup. I wanted to try and save myself the trouble of taking it in and getting ripped off and was hoping someone out there might have an idea what the problem was.

Please! Please help!

Hello guys. I have built inthe past one dc coupled amplifier and enjoyed its sound very much. But there were weak bass and dynamics. I felt that the cathode resistor is a bad thing.
My schematic of the amp is here:

I tried changing the ultrapath into cathode cap and vice versa but no difference in sound.

Do you think that it is possible some DC coupled without that big cathode resistor? Something like this,justvery big negative grid supply instead of the Rk voltage drop? Will it work? What are your opinions?
Thank you. Best regards, Michal

Hi all,

I have built a guitar amp and I am having some issues with supplying v1 with DC.
I basically took a Mesa Boogie design from their Rectifier series but it is too noisy in my case.
The setup is: 6.3V heater supply to full wave bridge rectifier( uf5408) to 10000uf. I even upped the filter to 30000uf without success.

Where am I getting all this noise from, especially when Mesa Boogie is selling this design commercially?

Hello everyone, I'm new in this forum!

I'm the proud owner of a Krell KSA 100 EUR amplifier. It works fine, but it has never been recapped, and I'm using it a lot. So I thought it is time to do some maintenance work.

Here's what I plan to do:

1. Replace all capacitors
2. Replace all potentiometers
3. I am considering applying new thermal paste and insulators on all the transistors. But I'm not sure if I should do that, if I'm not also replacing the parts. The stress on the PCB and on the components might outweigh the potential benefits.... Thoughts?
4. Clean all connectors
5. Adjust DC offset, idle current, ...

Anything else you would recommend doing, while in there?

I do have schematics for my amp, and before I take anything apart, I'd like to understand the schematics. I started with the protection circuit (the board at the rear end of the amplifier).

I do have a couple of questions about this:

1. The schematics shows some weird resistor arrays with switches, which I can't identify on the board. Instead of the 1k resistor and the resistor array, I see on the board a 100ohms resistor and a 12.4ohms resistor + a 100ohms potentiometer. From my understanding, this circuit shuts down the amp, if too much current flows through the 1ohm resistor in the output path. So my question is: How do I calibrate this circuit?
2. For C32 and C33 the schematics gives a value of "100" but on the board it looks like its a 10pF capacitor. What is the correct value of this capacitor?
3. The schematics shows two 47uF capacitors (C28, C29) - one for each channel. But on the board I see only one 47uF capacitor!! What's wrong here?
4. Obviously the schematics I have does not exactly match my model (maybe a slightly older or newer revision). Does anyone have the schematics for my exact model?

These are just my initial questions 😀 and I guess there will be many more... 😎 so please be patient with me...

I managed to pick up a nice bargain today, a pair of B&W CM8 Series 2 to replace my ageing B&W 683's.

I'll be putting the 683's on Ebay unless someone would like to make an offer for them. They are in A1 condition and boxed with everything that came with them when new. There is a minor dent in one tweeter cone but it doesn't affect the performance at all. These are in the UK.

I am in search of a PCIe soundcard with coax/RCA (or BNC) S/PDIF (75ohm?) output;

specifically Not optical... (= "jitter"?)

I have no need, nor interest in, Surround processing;

The bulk of my music sources are CD/SACD (stereo), along with some sound tracks ripped from DVDs (DoP?).

Ideally, a software-driven (i.e. digital-domain) subwoofer filtering/output would also be spiffy (can be analog or S/PDIF out).

The Holy Grail: PCIe sound card with active, software-driven (digital domain) active crossover (3-way, stereo)... analog or S/PDIF outs.

PC is Lenovo C30 (dual Xeon E5 v2 CPUs, 32GB DDR3, 2@ PCIe x16 - one for Graphics card, second 16x slot yet unused.. also PCIe x4 available) Win10Pro 64.... may eventually move/re-rip music library to NVME/PCIe card (PCIe x4). FREAC/EAC/Handbrake currently installed/used... Win10/WMP12 also works with FLAC.

My ASUS D2X card worked well in my old Win7Pro 64/Corsair 850W PSU machine; however, as the Lenovo C30 machine did not have a "floppy drive" molex/power connector (soldered one in, spliced off of SATA power connector)... the D2X did not seem to cooperate with theC30... Win7(XP?) was possibly the last for the D2X... IMHO the out-of-reach power connector placement was a stupid, stupid idea (never did figure out if both 5VDC and 12VDC was needed)

Purpose is good tunage for my Classic Airhead (BMW) motorcycle hobby shop.

FWIW, I still have a yet-to-be-assembled Wroclaw Audio Force Najda (Latest frimware and modified for S/PDIF in by Nick) in the box (software is for XP... possibly Win7??)... an Orfeusz 206 also collecting dust (gifted to me by Nick, for lending some help). Also, a short stack (3@) of Cambridge Audio A1s (not v.3) modified for single-input S/PDIF DACs... bridged TPA3116 (@ 22/19VDC) may suffice for Subs....

Hello, just completed the bias on my tube amp, is it ok if one of the tubes have a very slight glow in the middle of it? You can only see the glow if the lights are off in the room (totaly dark). As well the amp sounds fine, and it takes about 10-15 minutes for this to happen. If the lights in the room are on, can't see the glow. The tubes are 6550's if that matters.

Thanks

Rino Odorico

I have a question to ALL.

Two years ago I had cheap tweaks with my KEF Q100 coaxial speaker. It was trial and error.
[comment]
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1ª Why when I add a RF ferrite to the woofer wires I have more bass and faster?

2ª Why when I add a RF ferrite to the twitter wires I have more too much HF?

3ª Why do bypass with a small 10nF polystyrene the HF are less shrill and more pleasing despite being more detailed than before?


I have my hypothesis and I have read others but I still do not have it clear. Please, serious answers.

FS: Bruno Putzey's G-Word with Hypex HPR and HNR 12 regs

I can't imagine anyone wanting it in the box it is in. But willing to send it as is.

The price will be same with or without the enclosure. (The volume knob is not supplied) I'd like to keep that.

150 Euro excluding shipment.

I do accept paypal.

In 100% percent working order. I just haven't installed a switch to switch between the two inputs.

Hello all,

I am about to start working on my Opera Consonance M100 plus amp, and would like to review the schematics before diving in. Does anybody out there have a schematic that you could email me please and thanks?

Cheers

Hey all!

I am currently working on tuning my DIY speaker, but I have some bass problems.

When I play at 80% volume, the bass plays very well and still is clean, but when I play it at 100% volume, the bass drops so much that it is less bass than what I had at 80% volume. As if I lower the volume for the bass, while in reality I actually increase the volume..

Has anyone experienced this too? Or does anyone know how to solve this?


Im using my fully custom FXtreme DB450 boards for this, which has the following specs:

------------------------------
-ADAU1701 DSP

-CSRA64215 BT

-TPA3116D2 x2 (4 channels, set to 26dB Gain)

-TPA6132A2 opamp (Between BT and DSP, Gain set to 0dB)

-AD8608 Precision opamp (Between DSP and Amp chips)

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

BTW: The high gain in SigmaStudio is for low-volume Bass Boost, as far as I know that is not the problem.

Note: Got it all fixed, there was a problem in my design..

==To the usual Mylar/Polyester used for diaphragms with various coatings...

How about Polythene coated with anti-static 'licron' or whatever its called....

Polythene is a whole lot easier to get....

Hi,
A buddy want to swap his 40 years old lytics...one speaker seems weaker whatever he îs standing in his room
Budget is a concern and some capacitance values in serie are highs.
Being in CE, I imagine some Mundorf lytics plain serie should cop, but I will measure the capacitance of the caps
Does capacitance move for lytic serie caps after 40 years...higher, lower ?
There is also no bypass, I have eventually some old styrens from philips I can give him...but is it good to mix a slow esr cap with a very low one of a tiny capacitance ? Seems an old way to bypass with 0.1 uF but is it still usefull todaý?
Cheap MKP in the 2 numbers range may fit on the pcb...but often I found it brighty if I remember from my limited speaker experience ?
I thought MKt that ESR lies between lytic and mkp are cheaper, but is that not also colored as the russian K73-16 are ?
What could I do to stay cheap? Bypass ? Cheap mkp or expensive Mundorf , generic mkt? ...
need to be axial for the pcb.
Sorry too much questions...no polemic please, just what was your experience to stay cheap and good enough either please?

I am looking to buy a alpine pdx v9, it is $850, but on amazon its $420, the downside is it isnt a authorized seller, but according to the reviews the amp works 100% and it seems legit. Im looking for your guys opinions

Hello guys,

I am starting to learn all about designing 40-50mm headphones drivers and large studio monitor speaker drivers.
I want to know what is the absolute best and most professionally used software in this field.
Now I understand that “best” is subjective, but I believe that there are softwares that are more professional and are in a way leading the industry of speaker design. (Headphones and Studio monitors both)
Any recommendations?
Your help will be greatly appreciated!

Best Regards,

Tom

My DIY sub design is pretty good, but if you go too loud (and not *that* loud), the bracket that holds the voice coil starts rattling a little, and indeed I think there is a tiny bit of space somewhere.

Is there some fix recommendation for it, or is it 'start over'?

For example: is there some recommended sheet of maybe compressable rubbery material I can just squeeze into the gap and hope it'll stop the final bit of vibration?

Hello,
I have a polite request for help in identifying loudspeakers that I bought "for a penny" 🙂. I bought them without the ability to check/look inside, mainly due to the rubber speaker suspension and optically good condition of the enclosures. Maybe someone had something "like this" once in his hands and knows what it is ?
Going to the point:
- woofer: 16cm in diameter, magnet 9cm in diameter and 1.8cm high, rubber suspension (with inscription SR161/2), holes in the basket sealed with factory fabric, dc resistance approx. 3.6ohm, poorly visible designation CKS 7x87-378 U3 on the magnet foot (not all signs readable), the speakers were originally mounted using a black tar-like sealing agent:

- branching filter: designation 001160 30A6, Frako ETF 7,5uF and 15uF capacitors, 9217-037 small coil and a second one in the back, wound using a trafo core and epoxy-impregnated (with partially illegible designation xxx201), resistor 8,2ohm:

- tweeter: absent, only 12x12 cm hole with 10x10cm mount remained;
- housing: 40x22x20cm, made solidly, speaker fastenings made using M4 threaded rosettes pressed from underneath into the front panel:


- connections: admittedly with the proud name "Magnat" but according to me non-original, quite crap (especially on the side of soldering - or rather its absence - see how "expertly" you can connect the wires), their holes in the housing seem not to be factory-cut:

- no company sign, no other indications.
I have tried but unfortunately nowhere did I find any information about CKS speakers. I am thinking about restoring these loudspeakers, which is why I are looking for some basic information.
Best regards,
Pawel

I was about to make the famous Rod Elliott's project 97 to drive a TDA7379 (that I'm yet to do) when I remembered I made a headphones amplifier years ago (it was never used apart from me checking it worked) by joining 2 different schematics for different uses, so I thought: could I turn that one into a preamplifier? What should I modify?

1-Do you think changing the output components values into the ones that P97 have is enough (6r8 to 100r, 220uF to 10uF and 10k to 100k)?
2-Should I remove that 1uF between the inverting input opamp and the Baxandall tone?
3-What about input components, should I modify those?
4-The headphones amplifier was made to use a single 9v PS, do you think it's possible to modify it to use a dual supply? Or it isn't necessary (I think it isn't)?

Or should I leave it as it is?
Or for some other reason it isn't suitable?
Or should I just make the P97 and stop bothering!? 😀

Here are the schematics:
The weird headphones amp:



The P97 just in case:



The TDA7379 shcematic from the datasheet (don't know yet what to modify ) :

Hi All. I have a Star Sound 6500 amp. I stand to be corrected but I think it is a copy of the Atomic 5K.





Another tech tried to repair the amp but just messed it up. I got the amp with the drive board missing. the guy damaged a few tracks to the drive board and also broke the vias. I was able to trace most of the track but just cannot for the life of me trace just one track. this is on the center pins the one that carries the voltages. Now on the drive board this is pin 6 that goes the the op amp U4 on pin 7.



Now I need to find out on the amp board where does pin 6 go to. Does it join with pin as it looks like it does.

Sold

This item has sold.

I have the following TubeCad Boards with parts for sale:

PS1 power supply with TubeCad supplied parts…..$65.00

Aikido Octal Dual Mono pre-amp boards. 2 boards with TubeCad resistors and caps…$85.00

Both include construction guides. Note that these are just the parts supplied by TubeCad, other parts are needed for completion.

Pricing includes shipping. PayPal (gift) with US shipping only.

Please advise brand and condition. Ships to Chicago. Thank you.

Sold!

This item has sold!

I have a Siglent programable power supply for sale. Model SPD 3303c
This is a 3-channel programmable supply with 2 variable channels and one fixed.
The variable channels are 0 – 30 at 3 amps each.
The fixed channel is selectable for 2.5, 3.3, and 5V at 5 amps.
$175 includes shipping.
PayPal (gift) and US shipping only

I have a triamped main system using the Altec Model 19 parts in an MLTL cabinet with the Altec 416 alone in the 15 cu ft cabinet. I have been driving the woofers with a JBL 6290, way too much power and I think there is a better choice for the 416's.
I use a Pass F5 on the horns and have a AMT1 used as a super tweeter, using a variety of smaller amps for that.

The sound is good (I may remove some stuffing in the cab as an experiment).
The 416's and MLTL keep the lower register effective and there is no "bump" at 100 hz ->150 hz, as is typical for the stock cabinets.

What I'm seeking is a good amp design that can control the Altec 416's and is a better fit than the JBL.

Hi, I have an old Akai AM-2250 amp. Some time ago it stopped working through one channel. After asking around (on this forum a while ago) it was suggested that the STK amp unit was probably the culprit, so I got a new STK465 and recently got round to replacing it. Having done so, the same problem persisted.


I then noticed that a fuse had blown - there's a bank of three fuses in the middle of the board, and one of these had failed. It's a small 20mm 1.25A fuse, so I bought a pack and replaced that. When I turn it on, there is a loud buzzing coming through the channel that didn't work, which lasts for about 2 seconds, then the fuse blows again. I tried it with two new fuses, same each time.


I'm not technical and at the end of my expertise with this - this is a last attempt to find out what could be causing one channel to fail and the fuse to blow. Any suggestions on what to look for, or what could be the issue?


Thanks for reading 😱

Greetings

I am a new forum member who is interested in learning about building amps.

I am currently building a DIY speaker kit. I also am interested in acoustic treatments.

I hope to learn a lot here, and hopefully someday be able to contribute.

Allan