Hello All,
I have a 19-year-old Mark Levinson model 431 power amplifier. After sitting unused for about 2-years, I wanted to compare it to my current amplifier. I powered it up for a few days to let it warm up. While checking the input and output to adjust gains for the two amplifiers, I noted a -140mV DC at the input, the output was 0VDC. Both channels measured the same.

My question is, can that be considered normal? The manual says the input is a balanced topology, but I use it in single-ended mode. I noted that if I add a load (if that is the proper term here) of about 1K, the DC goes to zero.

Thanks for any help
Cheers,
ceulrich

I plan to recap this crossover and put new speaker cable binding posts on this ESS AMT bookshelf

I emailed ESS. They told me that they're looking for the manual and schematics of this ESS AMT Bookshelf.

here is the schematics I found:
https://audiokarma.org/forums/index.php?threads/ess-amt-1d-schematic-upgrade.306388/




On this particular crossover, which part should I replace? Thank you in advance!

I'm building the streamer using these instructions



However, all I need is a spdif out to the DAC.

I understand that I can use the TransportPiAES board instead of the HDMI board. But I'm trying to cut costs - can I use the TrasportPi MkII instead? The author mentioned it, but it looks like it's a different shape. Will it fit? Or what can I use for the spdif out with this configuration?

Thank you
Ken

Good day all. I ecently got a Velodyne CHT avtive subwoofer from a friend. Im needing some advice regarding this subwoofer....and Im hoping to get it here. When I initially plugged it in....it worked but as soons as I increased the volume...it would clip and the relay would kick in. It would only start playing again once I lowered the volume. I checked voltages going to both op amps and its spot on 14.8 volts. What i did find is.... on the attached schematic..... Q709 and Q708 which are the output transistors base-collector come up as a dead short when testing with a MM on continuity. On Q713 and Q716 the collector-emmitter comes up as dead shorts using the multimeter set to continuity. There are numerous other components in the circuits like resistors, diodes and even caps that do the exact same thing. Polarized caps do the exact same thing when testing with a multimeter set on continuity...but it only does it for a second and then no continuity. So far I have replaced all the smaller transistors...becasue I had them. Im hoping some of the more experianced techs could maybe have a look at the below schematic and maybe offer some advice on what to check...if at all possible. any help would be appreciated. Atatched schematic is from Velodyne support. Thanx in advance.....have a blessed and prosperous 2024.

Note: this curve tracer project has a come a long way, and is now called pypsucurvetrace. This thread is for documentation, development, and discussion PyPSUcurvetrace. The software is available as a Python 3 package at GitHub and documentation is available at ReadTheDocs.

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

I recently was looking into curve tracers for power transistors. I want a setup that allows straight-forward and automatic interfacing of the curve tracer to a PC (for data acquisition and also for instrument control). While there are a few testers available for small-signal transistors, those devices don't seem very useful with power transistors.

So... I was sitting in my workshop, fiddling around with my Voltcraft PPS bench power supplies. I remembered that these PSUs have a USB computer interface, and it's actually not so difficult to talk to these PSUs via USB. I have used the PPSs at work with a little Python program that sets current or voltage limits, and reads the true voltages and currents from the PPS. The readings are surprisingly accurate (as confirmed with different DVMs). The different PPS models have different voltage and current limits, but most models will have no problem to torture a power transistor.

The idea would be to use two PPS PSUs with a computer to determine the voltage/current curves of a transistor as follows:

• The first PSU provides the voltage across the transistor and the current flowing through the transistor.
• The second PSU provide the voltage applied to the gate or base of the transistor.
• The computer sets the gate/base voltage (second PSU) and then traces the curve for this gate/base voltage by varying the voltage and current current limits at the transistor (first PSU).

I am pretty sure it would be straight forward to scan the U/I characteristics of a power transistor this way. However, the process would be rather slow (say 1 second per data point or longer), because the communication between the computer and the PPS is slow, and the PPSs are slow in setting the and reading the voltage and current values. I guess it might be tricky to keep the transistor at a sufficiently constant temperature during the test sequence. Do you think this might be an issue? Do you see any other issues with my idea?

Hello Everyone!

Recently ive been working on some amplifier project and im using the TDA1558Q. Im very confused with this chip, First of all ive copied the exact stereo circuit with the one in the datasheet and im facing problems. While pin 14 is low (Mute) everything is normal about a 100mA draw, but when the pin 14 goes high (Vp) it draws 1.2A with no external input and it measures 2.2V dc at the inputs and 6+V dc output. I thought it might be a faulty chip so i used a new one it does the same thing. Anyone that knows what is going on and what am i doing wrong with this because im very confused.

I sell PCB for MM preamplifier Actidamp MK3, designed by Mr. Dudek. It is a preamplifier with active damping. Another possible improvement of modern operational amplifiers.

I will supply all documents to the interested party.

Price: 30€ + shipping

Payment: Paypal, Wire transfer
Worldwide

Dear All,

My Nad C316BEE is broken : it does not turn on !
To fix it, I am looking for the schematics ( service manual ).
Of course there is service manual online, but for only the initial version.
Mine, version V2, has the Main VM3.0 card, with a different diagram.
Also totally different the POWER SWITCH board.
Without these diagrams, I do not know how to repair ( possible that it is problem with +5volts lost ? ).

If any of you had the diagrams ( sm will be the best ) for this V2 version...
And if he agrees to communicate them,
I will be eternally grateful to him !!!

Raymond
( pardon me for my poor English, I am French )

NOTE: The current design has proven to work rather well and has great fit and function at this point. Hardware needed is M3 bolts (8-20mm bolts work, ~12mm is ideal) and an associated M3 nut. There are 4 different lengths you can print, which are attached below (57mm, 100mm, 130mm, ^ 160mm)

I'm giving these iterations away for free as a thank you to the diyaudio community. Interested parties who need me to print parts for you just send me a prepaid shipping label so no money needs to be transferred. Reach out via PM to coordinate. Cheapest option is print yourself or use a buddy who has a hobby 3D printer.

I created the wire post to help with wire separation and management in my F5m chassis (but works on all amps), and plan to share a final product as I go through iterations to optimize the design. There are now 4 different versions that are based on height (57mm, 100mm, 130mm, and 160mm). They all work well and create great zip tie points to hold wiring firmly in place and appropriately spaced (that part is up to you).

These mount to the bottom plate with a M3 bolt and nut (nut is technically optional). It will thread securely into the PLA print as the pocket/hole is 19mm deep and smaller than the thread outer diameter, however, there's also a slot if you want to add additional "rock solid" connection using an M3 nut (just slide the nut down the slot prior to bolting the post to the plate so the bolt threads into the nut).

The whole point is to create a structural point to connect to that guides and separates the various wire runs (filter board to amp board, amp board to speaker out, etc...). The goal is to make numerous versions for a variety of applications you can print at home (or use a buddies 3D printer, maker space, or fab house). The inspiration is from aerospace industry wire posts used to control and separate wire runs.

Although the material is "PLA" (Polyacitic acid), it's thermal properties seem to sill hold up inside the class A amps. I have not seen any deformation due to heat, even when the post is very close to the hot heat sink (heat sink is 60°C and PLA softens around 100°C) so as long as the loads are low (aka, just holding wires in place), the post does not deform under the heat loads.

I printed a bunch of these to give away to interested parties. Reach out via PM if you're interested.



M3 Nut just slides into the slot before bolting on.

TUBA completed as shown. Probably better for shipping not to have heat sinks mounted. Contact pins and bridges are included although they didn't come out in the pic.
100 +s&h.
Enjoy!

I was wondering if there is any support for establishing a “library” on DIYAudio consisting of different designs for custom punch/machining patters (in DWG format) for front and rear panels of various Modushop chassis?

For example patterns developed and actually used by members could be posted in an organized fashion, perhaps by chassis type, size, and application (e.g., generic preamplifier, ACP+, H2). Each design would be accompanied by a short description, e.g. 2 RCA input in 1/2” hole; 2 XLR D/size outputs, and so forth. One could then open files to see if configuration meets their needs and then submit them to Modushop rather than possibly incurring a drafting fee.

I’d be willing to work on this if there was interest and support from DIY Audio.

I’m asking if someone in Italy could help me contact the seller of some drivers I am interested in buying. They are listed on the subito.lt website. To be able to contact the seller I need to log in to the site, but I cannot do that as you need a Italian mobile number for the verification process. Would someone be kind enough to help me contact the seller?

Not many options for USB devices that can be used as a DSP/Xover for running 2 way active speakers? After lots of looking I've only found minidsp 2x4hd, sound blaster X3 and X4, and Asus Zonar U7.

So few options exist? There's like hundreds of single channel/headphone output USB DAC's.... but none have the ability to be used as active crossovers due to having only one output.
What are people using? I bought a used X3 and played some music (before trying it with apps to control 2 channels for the xover) and it doesn't sound clean enough to me to consider using it. I'm assuming the X4 is worse, as it's specs are worse. Then the minidsp 2x4hd has a rather poor review on audiosciencereview, and some people say the top end is missing some clarity. I'm coming from a pretty decent DAC I guess, or the X3 is this bad? So I'm worried the minidsp will sound worse too.. will it?

Any other decent performing mulitchannel output DAC I can buy without selling a kidney? It seems to be slim pickings. Also I prefer line-level output, or RCA.

SOLD!!

For Sale is one Sony VFet2 amplifier kit. You'll get ALL of the interesting/good/hard to find parts in closely matched pairs/quads. You just need to add the generic bits, a power supply, and a chassis to enjoy this beautiful and awesome amplifier.

This kit includes the following:

One pair of original DIYAudio VFet heatsink mounting brackets with predilled holes appropriately spaced for TO-3 cans
One pair of original DIYAudio VFet2 boards
Two complimentary pairs of original Sony Vfets: 2SJ28s measure 7.5v and 7.6v, 2SK82s measure 7.8v and 7.9v
One matched quad of original Toshiba jFets: 2SK170 measure 9.9mA and 9.8mA, 2SJ74 measure 9.9mA and 9.7mA
One matched quad of original Toshiba Fets: 2SK2013 measure 2.27v and 2SJ313 measure 2.27v
One pair ZTX450 transistors (unmatched)
One pair ZTX550 transistors (unmatched)
One pair of IRFP240 transistors (unmatched, but from same die)
One pair of IRFP9240 transistors, matched at 4.16v
Mica insulators for VFet TO-3 cans

Original Toshiba Front End Transistors:
2SK170/2SJ74 jFets were sourced from Spencer at FetAudio years ago. These are known/verfied original Toshiba jFets and a well-matched quad. 2SK2013/2SJ313 Fets were sourced from DIYA member NicMac long ago. They are known/verified original Toshiba parts and a well-matched quad.

Original Sony VFets sourced from Acronman at CircuitDIY years ago. These are known/verified original parts and a closely matched quad.

Here's a photo of everything that is included (oops, the ZTX450 transistors are not in the image, but still included):



Price: $475 via PayPal "Friends & Family" delivered to your door in the continental US.

Hi folks,

I found a working Technics SA-303 and want to replace the stock R703 (470ohms - 5 Watts) due to heat damage on the board (circled in red). I don’t think there are any faults. I’ve measured 40 volts across the resistor. That is 3.5 Watts for a 5 Watt rated resistor! I found a thick film 10 Watt TO-220 package resistor and a heatsink that will fit in the volume (30mm x 30mm x 30mm). Wondering if there is a more common replacement for these power resistors. All of the other 10 watt rated resistors are too big. Thanks. Schematic and photo attached.

Just gave myself a little gift for xmass.
Can anyone help me interpret some curves?
Basically just checking at first. Yes, i read some dayton brochures.

Here after hookup, i measured small aura fullrange, then four loose tweeters.

UPDATE NOTE: If you want to use an Antek 400VA transformer with this seat, you do need to use some 10-15mm spacers for the 130mm pipe strap. The slightly larger diameter of the 400VA over the 300VA transformer means there's a gap that exists between the chassis perforated plate and the strap ends. If you don't care what it looks like, then spacers really aren't needed as they don't increase the strength of the "grip". You do need to use longer M4 bolts (M4 10-12mm work for a 300VA, but 20-25mm are needed for 400VA. The spacers just make a cleaner look is all by flattening the tabs (see pics at end of this post and associated ZIP file with the 11mm spacer 3D file). Don't buy 150mm straps and think they'll fix the issue as those are too long. Stick with 130mm and either use spacers, or live with floating tabs (secure as a rock with either option).

I'm posting the 3D print files here for the Transformer Chassis Seat I created for my F5m build. Version 2 is now the most up to date (3-19-2024), which simply allows a "lip up" option to the perforated pate. The title to this thread says "Antek", but this may work for other transformers with similar widths/diameters. Making tweaks for other transformers is not hard, so feel free to reach out via PM to create a new version for other transformers.

For now, please see pictures from my build in the F5m Kit thread here: https://www.diyaudio.com/community/threads/f5m-kit.408290/post-7627904

Below is a zip file which contains both version 1 and version 2 STL & 3MF files for anyone to download and use however they see fit.

• Version 1 - Original Design, no slot for "lip up" perforated plate orientation. [I don't see any reason to use this since Version 2, does what this does and more. However, maybe being 2mm closer to the bottom is beneficial for a few folks.]
• Version 2 - 2mm Taller (allows more squish and squeeze) and has a slot to allow for "lip up" orientation of perforated plate if you go that route. Pics below are of version 2 showing the slot.

Hardware required:

• 2x qty: M4x10mm bolts with standard nuts to mount the seat to the chassis. [2x bolt and 2x nut]
• 2x qty: M4x10mm (or 12mm) bolts with lock nut, or lock washers, and fender washers to hold the pipe strap down. [2x bolt, 2x locknut, 2x fender washer]
  • NOTE: If you want to use a 400VA transformer you'll need M4 x 20mm bolts (25mm also works). Spacers are not a requirement, but will certainly make it look more professional. Spacer print is attached below, or use any spacer that is between 10-15mm.
• 1x qty: 130mm Stainless Steal Pipe Strap with Rubber Cushion (cost is around $2 or $3 for one, but you typically have to buy more than one)

Assembly

• Start by mounting the seat itself and ensure transformer has a little clearance around it.
• Set the transformer up with the wires off to sides to avoid interfering with sides of seat.
• Loosely attach one side of the pipe strap with the lock nut.
• With your three hands (yeah, a third hand would help as its tricky), put the other end of the strap on compressing the transformer into the squishy seat to get the nut to thread.
• Tighten it all up nice and tight....all done.

More to come as I try out different designs and try to make something that's more "universal" for different applications.





Here's a 400VA using 20mm M4 bolts without spacers. Still crazy secure, but kinda looks "janky". (not that anyone sees this once case is closed up)


Here's what the 400VA transformner looks like using 11mm 3D printed spacers. Just looks better, but no more, or less secure. Purely cosmetic.

Selling the first ACA Mini I built which used the ACA Mini Essentials kit, parts from Mouser and extra parts I wasn’t using. Upgrades include DynamiCap input film caps, a medical grade switching power supply, a P089ZB clone of a SMPS DC filter and Welwyn RC55 resistors in the signal path. Everything was mounted on a wooden board for expediency. Ugly, but sounds great!

$100obo including shipping to the lower 48.

Also included is a bare ACA Mini PCB and the original instructions left over from building a second ACA Mini using PCBs of my own design mounted on huge heat sinks.

Hello All

I have chanced upon a faulty Rotel RX 400A

The previous owner said when it was switched on, it briefly lit up (the front illumination) and then smoked and shut down.

On examining the amp, the transformer doesn't seem to be producing any secondary AC - only shows 3VAC.
The schematics do not show any clear transformer specs. It does produce various DC voltages using a bunch of resistor divider networks, but the max seems to be 47V (B1 in the diagram). There is also a DC smoothing cap of 50v 6300uF.
There is an odd 6.3v shown on the primary side that goes to the pilot lamps. Not sure what this is ...?

I am attaching a pic of the transformer, and the relevant extract of the power circuit schematic.

The amp specs are 25w into 8ohm per channel.

So... I am looking for some advice on the specs of a replacement transformer. I presume I need 220V : 50-0-50V , and maybe 100VA atleast? The pilot lamps are a confusing element here, but maybe I can build a DC alternative for them, and/or swap to LEDs. Any further info on this 6.3v is helpful.

Or should I junk the whole power section and drive it with a modern power supply to get 47v DC, and let the other voltages stand as they are off the dividers?

Any advice or pointers are much appreciated.

Hi There, need some help

i own an effect unit from Ensoniq the Dp4. I have problem with the input signals, there is completly distorted a lot of hum and noise.
i did a check after the D/A converting and the effects blocks. on the signal path after the effect which is going to the outputs everyhing is okay because i can generate i sine wave signal in the effect processor and it sounds good.
What are the possibilties of these issue ?

Grounding?
a faulty Tl074?

Looking for SOTA 15" sub driver. 20 - 80hz, in sealed enclosure around 150 liters. High end music system.

I'm looking for recommendations for tweeters that can cross at 1KHz. Planning on an MTM with dual 8" woofers that shouldn't be taken higher than 1KHz. It will be active, so steep slopes are possible and OK.

High on my consideration list is the ESS HEIL AMT...it's actually the only one on my list at the moment. What else can do this that's not a large compression driver needing a large waveguide?

Thanks in advance.

I currently have lowther dx4 in BLH cabinets, which bass is rubbish, my first plan will be to try and EQ some bass using Nelsons EQ board, if this works, great.

If not then i have 3 thoughts:

1. leave the drivers in the BLH cabs and build/add a couple of subs

2. make and transfer the drivers to open baffle and build/add a couple of subs

3. make and transfer drivers to TQWT (or ML voigt)


Would appreciate any thoughts/recommendations

Thanks

Hi there . Im looking for a tubeworks service manual for a RT921 reverb . Does anyone know where i can find one . Even the founder doesnt have any , says theyre obsolete .

One amp died when Main positive and negative power in crossed, and the other failed with a multimeter attached while connected to speaker terminals while loaded. Of these two are the components I have to replace with bd139 & bd140, IRFP064N, IRF640. The first amp I have replaced with bd139 and bd140, new 47ohm resistors & IRFP064N, and repaired a trace under the coils.
I have the other amp all with the same symptoms, but additionally, the pwm/protection board has some failed components I have been scouring the forum for. I found here the schematic to help Identify resistor values but no ID on the transistor in position Q5. I dont know what Q5 is, a pnp transistor or linear voltage regulator? https://www.diyaudio.com/community/...-type-3-protectionmarkedtype3-01-pdf.1270452/
Im also reading a handful of odd resistor values on the pwm board as well.

Where I can get a hold of a replacement board? Tracing Q5 to r10A (top), bottom middle leg to pin 1, left leg to C1898, But What does the right leg lead to seeing as it blown the trace? Probing what little left of the trace shows that its connected to pin1(bottom leg & top). What is the transistor of Q5?

Edit Feb. 2024: You want parts? Read this post carefully. Do what it says, all of it. Otherwise your PM might not get an answer.

This thread is for getting my big stash of tested and matched LD1014D (LU1014D) JFETs out to the DIY world!
So far I have tested and matched several hundred parts by temperature-controlled Vgs measurement and curve tracing (see details below). Additional parts will be added as testing progresses. These parts are perfect for building a DAO headphone amp, ZEN 9, F3, LuFo, SuSyLu, etc.!

See here for more information on how to find good matches from the data provided at the link below.

Test procedures:
All parts are testing and matched using PyPSUcurvetrace with calibrated power supplies, using two test methods:

• Type A test: measure the the Gate-Source voltage (Vgs) required for a Drain current (Id) of 1.5 A at Drain-Source voltage (Vds) of 2.4 V.
• Type B test: like Type A, but additionally also measure Id vs. Vds curves at Vgs = -0.6 V and -1.0 V.

Parts are measured on a temperature-controlled heaterblock at 40°C (except early Type A measurements, which were done without temperature control).
Vgs data are recorded in a list (sorted by Vgs, see link below).
Curve traces are plotted for pairs which have Vgs values that are matched to 30 mV or better (Type B only).

Prices:

• Type A parts: EUR 10 per piece
• Type B parts: EUR 15 per piece
• Shipping and handling per envelope: EUR 10 (international) or EUR 5 (Switzerland)

Matching data and part availabilities are here:

• List with Vgs data and parts availability
• Curve matching as described here
• Parameters (Vgs, gain, etc.)

How to order your parts:

1. Post a quick reply to this thread indicating your interest in getting some LD1014s.
2. Enter your details and the LD1014 part numbers in this form.
   Send me a PM with your desired LD1014 sample numbers, your full name and address (including country!), phone number (needed for shipping), and email address.
3. Wait for my reply with payment instructions.

Much of my source material (uncompressed CD track rips; no SACDs or vinyl), are 60s pop, r&b and soundtracks, which were often victims of excessively applied compression. And some tracks during multi-vocal passages and when orchestrations get busy sound “congested”; possibly due to poor miking/baffling (??), other acoustical and/or electronic causes. So, while not outright crappy (??), much of my music was certainly less than pristinely recorded and/or mastered, even though almost all were issued by major labels.

Further complicating matters was that I had originally attempted to wed this superb midwoofers with cone HF and MF drivers. Login to view embedded media
Luckily, I caught that mistake before wasting time and funds. Troy Crowe and I are now deciding among horn drivers to finish this build. The trouble is that no matter which drivers are chosen I might end up not smiling so much while those speakers are playing anything but my tip-top quality CDs. No doubt that’s one reason why so many horn speaker owners prefer SACDs and even less than high quality vinyl over most music released only on CD.

Thus, while I do have some well recorded and well mastered CDs, perhaps the only way to make most of my stuff sound more pleasing is through careful preamp selection-and/or, where possible, tube rolling and “voicing”, as Aikido owner PierreQuiRoule suggested.

To this end, I’ve heard the Aikido described as very neutral sounding. Whether this is true and/or is the same as transparent sounding, while either may be an asset for playing high resolution source material, how would such a preamp feeding my First Watt F4 power amp driving my >94db/m/watt horn speakers present my more sonically troubled CD tracks?

I’m hoping that the Aikido, built with high quality parts and using the right tubes would somehow behave friendlier towards most of my CDs. If yes, please suggest the best caps, even some of more costly Jupiter models. If the values are too big to fit on John Broskie’s updated Noval board, I might elect to ask John and Phil Marchand about the tradeoffs of redesigning the board to accommodate them.

John also mentions here that he suspects tighter bass can be realized with an electrolytic-free power supply. https://tubecad.com/2018/03/og0415.htm

Also important to know is which are the tubes known to create the most lifelike imaging and largest sound stage?

But which are the tubes which may be too revealing for my more crappier sounding CDs?

Alternately, is there another preamp which would be altogether better for my situation, such the Nelson Pass B1 Korg Triode, or others?

gone

FS Pair Nice Capehart Jensen C12R Field Coil Speakers $400 shipped
These are in excellent condition as removed from a working high end radio. Nice matching readings VC 8 ohm, FC 680 ohm. These have quite the following. Only $350 with free CONUS

At long last, I have completed the LX-mini Analog Crossover and posted
in in the Article section of FIRST WATT

It will serve as the documentation and assembly manual for the kit which
will soon be available in the diyAudio store.

Enjoy.

We can give this thread a try. The idea is that Vituixcad newbies who have a fair understanding of speaker making concepts but are amatuers with Vituixcad can ask away for basic help. It might even help keeping it as an accessible source for a Vituixcad manual.

Of course we would like the veterans to keep an eye out that the right thing is taught so hoepfully they subscribe to the thread and keep checking in.

There aren't many 12" tapped horns for prosound. The Lab 12 is a great driver for the price, has a strong cone for tapped horn high(ish) compression ratios, and a good amount of Xmax.
12" tapped horns can be much skinnier than 15" and 18" horns, and with the price of the Lab 12 ($165) one can use 4-8 horns and not hurt the wallet too much.
With multiple horns as opposed to one or two large 18" horns, you have more options for stacking and setup.

Figure with the 400w rms rating of the driver, huge amps aren't needed to drive the cabinets to full output.

So here is the breakdown:
$165 Eminence Lab 12 (readily available, been around forever, now two voice coil options available)
$60 per 5x5' 3/4" Baltic birch (2 sheets required)
$40 for Casters, Durtatex, terminal, screws etc

Simple folding, easy to construct. Will have handles and casters for easy transport.
38" High x 30" Deep x 15" Wide cabinet (about 10 cubic feet or 300L)
Low corner of about 35hz
15" wide cabinet maintains truck packing dimms
Group of 4 plus 2000watt amp will provide plenty of output for as little as $1600 ($1300 for 4 cabinets plus $300 for amp)
This build is with the original 6ohm driver. The new Lab12c may also work, not sure.

Lets call it "PAL12 Subwoofer" For P.A. Lab 12 Tapped Horn

DIRECTORY FOR THIS THREAD
AutoCAD drawings, 2D: (post #123)
$325 Lab 12 based PA tapped horn. ~35hz extension - Page 13 - diyAudio

3-D rendering: (post #127)
$325 Lab 12 based PA tapped horn. ~35hz extension - Page 13 - diyAudio

Construction Technique, order of panel installation: (post #129)
$325 Lab 12 based PA tapped horn. ~35hz extension - Page 13 - diyAudio

Initial measured results: (post #82)
$325 Lab 12 based PA tapped horn. ~35hz extension - Page 9 - diyAudio

Now that the sub is constructed and tested, we can post some final specs.
Operating frequency: 34Hz----120Hz +/-3db
Dimensions: 30"x38"x15"
Impedance: 4 ohms
Power handling: 400w rms, 800w program High pass 32Hz 24db/octave minimum
Weight: TBD

Hi,

I am selling surplus drivers left from various projects in the past that I do no longer need :

1) Woofers W-300. Almost like new. Asking 50 euros per piece, I have 4 units in total.
2) Mid bass units AL-170. Good condition. 70 euros for piece, 2 units total.
3) Tweeters KE25SC, highly valued. 85 for piece, 2 units total.

I sell only in pairs, shipping from EU. All speakers come with original boxes and are fully working. Used very little, mostly stored for several years.

I've just finished the build for the first pcb of my modular phono preamp project.

It does RIAA compensation and basic amplification suitable for an MM input.

I intend to design an MC stage pcb, an input connector pcb, an output connector and power pcb (perhaps with battery option), a rumble filter pcb. They will slot together with dupont-style edge connectors, allowing various configurations.

The two channels are independent in this pcb, roughly mirror-image, allowing a star-ground to be used at the power supply end.




SMT is used where possible to keep size down. PPS capacitors seem to be the best compromise for low distortion and SMT availability - here a single value, 10nF, is needed.

The RIAA circuit topology is slightly unusual in that each of the poles and zeroes is an explicit separate RC pair. Care has to be taken to keep the opamps stable into capacitive loads in this topology (the 33pF capacitors and 470 ohm resistors).

The nominal component values give exactly 75µs, 318µs and 3180µs time-constants. Alas I could only source 2% PPS capacitors, but 0.1% thin-film resistors are used throughout.


Where DC-blocking is needed I used back-to-back electrolytics of high value with a centre bias to keep them formed over time. The 22M resistors were a guess for this purpose - the time constant is measured in hours so in theory won't have any impact audibly.




There is no input DC-blocking capacitor, as my calculations show the tiny bias currents of opamps are not going to have any effect on a MM pickup (despite what a lot of people glibly state). 500nA in a 1k5 winding gives an offset of a fraction of a mV, and a few mA-turns of magneto motive force, insignificant compared to signal levels, especially when the inefficiency of the MM cartridge as a motor is considered. I think I'd need to see some hard evidence to the contrary, such as a plot of THD v. offset current.

Hello DIY'ers.
I have been given a Yamaha P2200 that is completely broken and not worth repairing - particulary so as the whole left channel has been removed. The best path forward is to try and reuse the chassis and toroid etc to build a whole new amp.
The power supply consists of a couple of 100v 22,000uf cans and I'll be replacing that fully. No problem there.
The rail voltages are very high though @ +/- 80VDC and I'm wondering whether anyone has some recommendations on suitable amp modules for this. I did read a very old thread in here about repowering a P2200 with Aussie Amplifier modules and while this is an option, it's a very expensive one.
So, does anyone have some thoughts on what I can possibly use or consider?
Cheers

Hi everybody,
I have two Fidelity Research FR-64s tonearms. They both work perfectly.
I noticed, however, that they have the different endpoints of the horizontal moving.

One of the arms can be placed directly above the TT spindle, just this position is the endpoint of its horizontally
movement.

My other FR-64s can be horizontally moved through the above mentioned endpoint a little bit further (apr. 20 degrees after the reaching the TT spindle).

The same situation by the moving right: the first arm can be horizontally moved just to the rest area, my other Fr-64s can be moved outward after the reaching the rest area a little bit further.
Is with this FR-64s something wrong and the arm must be repaired or serviced?
Thank you for any advice.

Paul

I've got the following circuit which keeps the level of an audio signal fairly constant.

Due to adding a VU meter circuit and only having a dual OP-AMP to drive the meter, I have an extra OP-AMP section.

Is it possible to connect the inputs to the + and - inputs of the OP-AMP and use it to drive a meter to indicate how much the circuit is operating on the signal?

After my fateful post re:LX Mini plan pricing, I did order the kit and plans from Madisound. Par for my course anyway, I decided to improve the WAF. Others have done 3D printing but I suspect they narrowed the focus a bit. These prints took a while and are (hopefully) cosmetic only. At least I’ve tried to make that way….



It’s not finished as I plan to incorporate a white wooden base (next time I would use a different filament color). And just to further my appreciation of “measure twice, cut (print) once” I managed to use the 6” flange OD as the bolt circle instead of the actual bolt circle. Damnit.

Z

Hey guys, can anyone, just based on their experience, tell me where should I start in trying to identify the following issue. Sub worked normally prior to this and nothing specific happened in between (like loss of power or something). It worked in the evening, turned off on a switch, then when turned on the next morning it started doing this.
I believe that the video is the best way to describe what's happening: https://www.dropbox.com/scl/fi/7vkc...nger.MOV?rlkey=yi8w2lbpc242or2b4rb7h1etn&dl=0

I obviously don't have a schematics and I would simply like to try to fix, won't die without it. I have some experience with electronics so I believe I will be able to test/remove/replace any component that can be tested with a UNI-T UT70B.
What I figured out so far:
- 1 component was missing, 47nF Capacitor next to the 4 'big' diodes, diode bridge? I've marked it in one of the photos. Capacitor was broken from it's pins, probably fell off from the sub at some point. I have replaced it (new one is on the image), but nothing has changed, same buzz before and after.

• All other components LOOK normal, no blown capacitors or burned resistors, visual inspection is good.
• I believe buzzing is not related to the input module because it behaves the same with or without it (I've disconnected it in the video)
• I can see a red LED next to transistors light up, it's on the board itself, could that mean something? Maybe that diode is a 'debug' info on some amplifiers?

I would like to know where would a repair expert start? Could have that 1 Capacitor, while missing, caused damage to some other component? Should I replace all 4 'large' diodes or test them while removed from the board? Replace big capacitors? Should I somehow test the transformer?
Without any extensive experience, I would start by replacing all 4 big diodes and their capacitors, and while ordering components, I would also order these 4 largest capacitors and replace them as well, but I would get stuck if that doesn't do the job.



Any idea is highly appreciated! Thanks!

I just have to post this, maybe the best beef, not just brisket, I have ever had in my life and I have had ribeye at Ruth Chris and generally BBQ very well using far less expensive but well raised beef.

Snake River Farms Wagyu Corned Beef.

If you know good meat you either or should know about SRF, some say best in the US and one of the best in the world, might be, sure dang expensive as a 12oz ribeye is $64, 32oz porterhouse is $129 or so.....each, ouch! At Costco they had the Corned Beef Brisket at $8.95lb which is quite high for that cut compared to other brands but had to give it a try. We picked up a 4lb one and cooked it at lower temps for hours in my Grandma's very old dutch oven, towards the end red potatoes, carrots, celery, all organic and good quality, forgot to grab some organic cabbage but still dang fine, getting cabbage in the morning!

Oh my, I am simply blown away as to how good it is and one heck of a value at the price.
We did not even use the good horse radish or mustards we have, just not needed, just the seasoning packet, which normally I throw away but it looked pretty good so tried it, it was perfect.

My next favorite is a pork rib roast slow cooked on the BBQ on indirect heat, mmmm.

With a last name starting with Mc....I have to do a bit of celebrating this time of the year

Rick

Last year at the Munich Fair I was impressed with boenicke w5, but unfortunately price is bigger than my limit , especially SE version
Since we have design studio and 2 CNC machine (for other purpose) I tried to do it something similar, but way is more than complicate since need to make holes on 3 different side s
No meter, if not counting our time, material, drivers, crossover and rest is almost 20 percent of price of W5SE
After I test it, sound is more than awesome
Here is couple pict from production process
BTW my workmates is also make pair for him, and we order material for one pair for our office

Hey there . Im looking for a service manual for a tubeworks RT921 reverb . Does anyone know where i can get one . Even the founder doent have one , says there obsolete.

SOLD

A complete unused kit for balanced inputs + volume.

1 Controller PCB
1 Programmed controller
2 Volume PCB
2 Main boards

SOLD!!

I've decided to sell my unassembled Iron Pre Single Ended kit. You get everything that came with the kit from the DIY Audio store. I could post an image, or you could just look at the link to kit in the DIYA store. You get:

• 1x Iron Pre SE PCB, good for two channels
• 1x Iron Pre “Twister Board” PCB for Input Selection with LED indicator and Mute x 1 positions (LEDs not included)
• Active Devices (QTY based on SE board)
  • 2x 2SK370 Matched JFET Pairs (J1, J3)
  • 2x 2SJ74 (J2, J4)
  • 1x BD139 (Q1 )
  • 1x BD140 (Q2)
  • 7x BC546 (T1, T3, T5, T7, T9, T11, T13)
  • 7x BC556 (T2, T4, T6, T8, T10, T12, T14)
  • 2X LM336 2.5 (U1, U2)
  • 1X IRF510 (M1)
  • 2X IRF9510 (M2, M3)
• 2X CineMag CMOQ-4HPC (high nickel laminations) Signal Transformers

Everything is completely new and unused/never soldered. I opened the static-safe just once in order to verify the contents to make this list. Your price is exactly what I paid for it from the DIYAudio store: $150 + $15 for paypal fees and shipping. Shipping to the continental US only. First response gets it.

If this is still available in the morning, I'll post a few images (exactly the same as what you see on the store link).

Hi Folks,

You can find it here:
Cronus Reclocking

Cronus is a module designed for providing clocks to and reclocking output from digital sources. Cronus forms the backbone for audio sources built around 2 other module types - Hermes and Rhea.

Cronus was a long time coming - because we worked hard to make the results not just good - but superb. We could have released earlier - but we wanted to get in all of the things we desired after two prototypes.

Special thanks to Miero for his beta testing.

Extra special thanks to Brian for being patient with my long design process - and for putting together awesome beta and production kits.

Cronus provides the following:

• An ultra low noise low impedance 3.3V power supply for clocks and reclocking section.
• A clock selection multiplexer to switch between 44.1 and 48Khz time bases.
• A selectable/bypassable ultra low phase noise clock divider to supply 1:2 or 1:4 clocks to a source.
• A synchronous reclocker that re-clocks the audio from the source back to the master clock. This brings all signals back into alignment with the actual master clock regardless of source jitter - thus your final signal is as good as the clock you supply - which is to say - excellent!
• Pads for pluggable clock sockets based on standard DIP(8 and 14) clock - See Rhea thread for more details.
• An interface for connection to our isolation modules for various sources - See Hermes threads for more details. Hermes isolates your DAC completely from your source.
• Interfaces for connecting to B3/B3SE and any other PCM/DSD DAC.
• SMA and uFL connectors for external clock signals (both in or out)
• uFL connectors for PCM/DSD output.

Some useful things to keep in mind:

The re-clocking section makes use of a Potato semi FlipFlop. When using a FF in this way the frequency of the clock input supplied to the FF must be at least 2 x any signal. For this reason ~22-24Mhz family clocks can be used for PCM signals up to 192Khz - for up to 384Khz you must double that. The device is capable of up to 768Khz PCM.

The module is designed for around ~5VDC input - but it is fine to go higher (absolute max is 16VDC) depending on the load you are putting on the VREG (adm7150) please refer to the datasheet about limits. The max current is listed at 800ma. The current consumption will vary depending on loads and audio frequencies. In testing using Crystek clocks (50Mhz family) I am drawing well under 150ma at 384khz. Keep in mind also that Hermes modules are designed to be powered on the clean side by the Cronus power supply.

The clocks are isolated from each-other and the rest of the circuit by utilizing L/C filtering with ferrites.

The Cronus is designed to work with Sources that provide a clock selection signal (CS) and can accept an external audio master clock - it is currently tested with two Hermes modules. Hermes-BBB for the BeagleBone black (using Botic distro), and the Hermes-Amanero for the Amanero USB module. There will be a thread for each. Both are tested and work up to 384Khz.

I will fill in more details to this post as necessary.

A manual is under way for each module - but I hope you basically know what you need right now.

The Hermes and Rhea threads will fill in a lot more detail.

I have also attached the pinouts of the .1" headers on the output side of the cronus and the Hermes header.

Note: If you use the terminal blocks - it is recommended to mount them on the bottom side so they don't interfere with uFL connectors etc.

Ask away!

Been a long time since I have posted in here. Starting a Tube Lab SPP build and have ran into an issue with a bit of a solder bridge and was wondering if this will be an issue?

R204/R203 and pin 8 on the V200 tube socket? I've been trying to clean it up🥴

Looks like R204/R203 are connected? But definitely get the solder away from pin 8. Just want to make sure before I overdue it trying to remove something I don't need to.

Thanks in advance

Hello everyone. I am designing a 3 way crossover in Xsim. The frequency is OK but the impedance response is terrible. I have tried Zobel networks without success or even much improvement. Could someone please point me in the right direction.
Also, on the frequency response traces, the system trace is higher that the bass and mid response. Surely that can't be right! The maybe but not the bass. The Xsim file is attached.
Thanks for your help.
Peter

Automatic Volume control for online TV 📺 commercials.

Today I run across streaming channels where they increase the volume on commercials ant thing on the market or schematic to stop 🛑 this from happening

Dave

Please let me know if you have any questions about this board. I have one of these at my studio in Orlando, FL. East Rom Suites It is by far one of the best consoles for a small studio footprint. It is definitely an amazing bridge between analog and digital.



The Standard information:

• 32 x 16 x 16 'Insert Router' for up to 16 external hardware processing devices
• Hardware processors can be inserted via console controls or cross-platform drag-and-drop software browser
• Stereo or 5.1 EXT monitoring outputs with independent Main and Mini monitor control
• Hardware processors can be inserted individually or as 'chains'40 input Super Analogue summing console
• Stereo Aux Send and 4 x Mono Sends per channel
• 4 Stereo Returns with full stereo mix bus routing
• Dual Stereo Mix Busses with summing Inserts and reassign In Line' DAW monitoring with 'SuperCue' headphone mode
• Stereo or 5.1 External Monitor inputs
• Stereo digital I/O (S/PDIF, AES/EBU) with SSL converter technology
• iJack front panel Monitor input
• Heavy-duty external PSU16 analog line channels with two inputs per channel
• Artist Monitor output with independent EQ and monitor source selection
• Single button push flips control between the analog signal path and DAW software
• Multi-layer control of up to four DAWs simultaneously
• Ergonomically advanced hybrid hardware control surface
• Digital scribble strips for constant visual feedback
• Fader-linking for analog channels
• Additional motorized 'Focus' fader for simultaneous DAW/Console control
• 16 channel strips each with motorized fader and assignable rotary encoder
• Total Recall for analog console controls
• General purpose MIDI controller mode
• A-FADA or MIDI Fader automation
• Ethernet MIDI connectivity
• Simple drag and drop insert router page for configuring hardware device chains and loading inserts
• Intuitive cross-platform remote browser for system configuration and project management
• Cross-platform 'Logictivity' remote browser interface
• Programmable hardware buttons for sending standard USB keyboard commands

- has been a popular build in Europe and spoken of, like Karlson boxes in general, as playing very loud with very little visible cone movement.

I would assume its based upon Karlson's 2nd K12 with a distributed slot port which appeared around 1956 and published in the July 1958 issue of Popular Mechanics. Its 3 port slots are much larger than Karlson's K12 with 6 saw blade-width cut slits, so should have less velocity. The panel above the speaker baffle, fully perpendicular.

IIRC, there was a build some years back on Diyaudio, but I've not been able to locate the thread or post.

Article https://i.imgur.com/SBDGevY.png

Plan http://home.planet.nl/~ulfman/images/Plans/new12in.gif

Karlson's 2nd K12


a couple of Karlson's mid 1960's K12 - one apparently offered with a blank port panel

(the first pair are mine)





A down-scaled version of the "Dutch" Karlson 12

I don't think there are many of us left using the Beaglebone/Hermes/Cronus. It seems development for the Botic driver has been dropped. I have been using GentooPlayer but the developer no longer supports the BB. He said it's not worth his time. This is really too bad because the BB is much superior to the RPi for our purposes. One alternative is supplied by IanCanada. He has a lot of products and it takes some time to sort them out. Just thought I'd post my experiences with this in case anyone is interested.

I use HQPlayer on a separate PC to convert everything to DSD256 and send over the network to the BBB.

I purchased a FiFoPi from IanCanada along with his PurePi power supply. I connected the BuffaloPro to the FifoPi using I2s. Just to get started I loaded RoPieee on a RPi4. Had to choose "Generic I2s DAC" nothing else worked. The best I could get was DSD64 using DOP. This is apparently a limitation of Linux on the RPi. The BBB does not have this limitation even though it uses Linux as well.

Initially I felt the sound was improved and more detailed but a little forward in the upper midrange. Bass was very good. I'm told that the clocks need time to burn in so I listened to this setup for a week or so. Ultimately it became a bit fatiguing. I could maybe make some adjustments in my speaker crossovers to help. For now I have gone back to the BBB/Cronus but substituting the clocks from IanCanada. This is a happy medium with bit more detail but not quite so searing.

Check this out:

https://www.stereophile.com/content/davina-loudspeaker-prototype

What's your thoughts on the planar line array, done like this?

I am planning a small size 3 way with Dayton RS52AN which I have, Initially brought with an Idea to build Black Box (Dayton RS270S-8 + Dayton RS52AN-8 + Dayton RS28A-4) --https://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_Black%20Box.pdf but later to my delay RS28A-4 has become obsolete.

Due to space constraints Iam not opting for http://zaphaudio.com/ZDT3.5.html

As I require a small footprint 3-way speaker, My thought is to go with a passive radiator for the woofer.

Has anybody tried building a 3-way Dayton RS52AN ( other than the above builds )?

Kindly help me to complete my build, your inputs are highly appreciated.

I get second hand all in one box micro stereo with 3" speakers and sound of it really needs upgrade.

I made measurements in room from 1m and there are problems to solve. Room modes have very little influence and holes on 500 Hz and 1.2kHz are from speaker.
Black line is bass reflex port near filed and blue is speaker near filed measurement.
Port+box have very low Q, probably because air leaks, this can be easily fixed, but can help only increase very little in bass response.



My first idea was Alpair 5.3.
Speaker box volumes are 1,75 L what is very little but it cannot be increased.
Simulation of Alpair 5 in existing box with existing port ( 30 mm diameter, 80 mm length) give not best results, solid lines on image
Optimized volume configuration lines are doted, 3,58 L box, port 30 mm diameter, 80 mm length.

What other 3" FR speakers can be used with small bass reflex box volume?



If I increase port length in simulation to 140 mm change is to better but little.

Looking for a Tripath TA2020-020 chip to repair my old Charlize

Anyone got one laying around?

Hi, I am wondering if anyone has any information on 4033X's parameters?

Previous links with datasheets appear to be removed a long time ago.

On radiomuseum (without sources), it states that it requires 4V filament, but stated the 6V tube, 4033L as "Normally replaceable-slightly different"

I note that online tube sellers commonly label 4033X together with NT37, which was stated to use 6V (http://www.r-type.org/pdfs/cv1220.pdf)

Any ideas if 4V on radiomuseum is a mistake, or could the 4033X be one of those tubes that are usable on both listed voltages?

March 24, 2023 / Dallas, TX

Miller Audio LLC ( https://milleraudiollc.com/ ) is re-introducing the Dyna-70 Ultimate Upgrade for the Dynaco ST-70 to the DIY audio community. Several years ago Erhard Audio introduced the Dyna-70 Ultimate Upgrade. In our testing and listening trials, we concluded that the Dyna-70 was the best of the ST-70 driver upgrades that are in production and available today. We built and integrated a number of Erhard Audio Dyna-70 Ultimate Upgrades for our ST-70 customers. The Dyna-70 sounds so good the kit sells itself once you hear one.



The Dyna-70 Ultimate Upgrade is different than most ST-70 driver updates offered today because it isn't just an audio driver upgrade, its also a power supply upgrade. In fact, the truth is a Dyna-70 is a more expensive upgrade than just replacing a driver CCA, and it provides the ST-70 something it has always needed- more power and filtering. The Rectifier tube and multi-section cap can have been replaced with on-board, solid-state rectification and a minimum of 2-3X of additional filtering capacitance. It also features an on-board in-rush current limiter (ICL) with a 2-stage warm-up cycle for the signal/preamp tubes to come up before the output tubes, minimizing warm up noise. The Dyna-70 Ultimate Upgrade now comes in two configurations at different price points: Automatic Bias or Manual Bias.

The Dyna-70 Ultimate Upgrade is now available and in production. Visit https://milleraudiollc.com/ for details and contact information. We offer a full selection of NOS 6SN7's, as well as a comprehensive selection of new production EL34 / 6CA7 tubes, and film coupling capacitor upgrades from Mundorf and Solen. We also offer the Dyna-70 bare PCB for DIY'ers in both auto-bias or manual bias configurations, allowing DIY'ers the ability to pick their own parts or experiment with various components.

Miller Audio LLC will be demonstrating the Dyna-70 Ultimate Upgrade at the Lone Star Audio Fest, June 2-4, 2023 in Dallas, TX at the Embassy Suites Hotel, Dallas Galleria,
14021 Noel Road, Dallas, Texas, 75240

For more info on the Lone Star Audio Fest (LSAF) visit: http://lonestaraudiofest.com/

We welcome everyone to stop by and listen to some of the best sounding ST-70's you'll ever hear.

Looking for anode reactors and filter chokes for a new project.
Anode choke please 30H 50mA and more, filter chokes minimum 80-100mA 30-50H or similar.

If you want to sell please let me know what you got!

Thanks....

Up for sale is an used class A/B power amp of dynacord, model L1800FD.
Very good condition, used for hifi only.

I am willing to trade, the price is 550 EUR + shipping.

Looking for used Jensen JT-11P4-1 input transformers or the JT-11P-1

If you want to sell please let me know. I am located in the EU.

Thanks!

Good afternoon, I am writing to inquire about something specific. I have a Technics SU-7200 to which the power transistors have been changed, and that ones are now short-circuited. Could someone advise me on whether using the original 2SD526-Y and 2SB596-Y matched transistors would make the amplifier work perfectly, or if there are other transistors that might work better? I'm not an electronics expert, but I have some knowledge. I would be very grateful for your help as a humble radio enthusiast. Thanks in advance.

Hi all,

Well, I reckon this is going to be a quite short thread as my feel is that what I am looking for does not exist ... But knowing that there are many knowledgeable people here there might just be someone knowing something about this ...

Is there an ultra-low distortion (<125 dB THD (DC to ~30 kHz), non-GFB, discrete components (non-opamp), non-complex design (basically "not that many components") DAC line level amplification circuitry (gain 5-10x) in existence somewhere accessible? I am asking because MarcelvdG's RTZ FIRDAC design in this post:

https://www.diyaudio.com/community/...t-register-firdac.379406/page-55#post-7419240

shows great potential, however, I would prefer to have the subsequent amplifier be a non-GFB & discrete design (and, yes, there need be filters but "first things first").

Yet I have never seen a non-GFB & discrete design with such low THD values - so my guess is that it doesn't exist ... ? Or may I just have missed it?

Cheers & thanks for reading & maybe replying with good news ;-)

Jesper

4x Texas Components Corporation - Bulk metal foil resistors / Z-foil resistors - TX2575 133Ω 0.1% - SOLD

Asking 40€ 25€ + shipping costs and any fees.

If the price is off let me know or make an offer.

Please contact me through PM.

Inspired by StigErik’s hybrid Magnepan speaker project (please come back StigE if you are reading this) I’ve decided to put together an unusual hybrid speaker system comprising Maggie ribbon tweeters, ESL mid range (cut out of some old gen 1 Acorn panels) and OB woofer arrays. The ESL mid range will use a 3 micron diaphragm.

On paper it probably doesn’t look very sensible to mix 3 different transducer types but I’m in a position to try it without going to enormous expense and so why not give it a go. To maximise the chances of success I will be using Audiolense for the crossovers etc.

Still in the planning stage but I will post updates as I progress.

Every now and then, we do something totally different, for fun but also for bench-marking.

This is almost 180° to what we normally do.
No FETs, no NOS parts, no 0.3% matching (although hfe matching does improve performance significantly).
All parts are in active production; you can get them from Digikey or Mouser for very little money.

It is Class A, has no global feedback, can deliver +/-10V into 30R before clipping.
It delivers 1Vrms into 30R at an amazing -97dB THD, and has a -3dB bandwidth of 2MHz.

You can read about it here :
http://xen-audio.com/documents/SLHPA/SLHPA Description Public 171005.pdf


Patrick

.

Hey gang, so I have this old valve radio which has an ecc83 preamp tube run as a two channel stereo and then there are ECL86s for each of the channel in the power amp section.

Now, although it somewhat worked while still in the wooden enclosure, something got damaged while i was taking it out. I don't really feel like bothering to measure all the old dusty buggered semiconductors, also the construction of the multiband radio receiver is a big mess.. or maze.. or both so to get to the board where the amplifier section is mounted is extremely inconvenient, that is why i have decided not to try to mend it but rather salvage what i know is good and functional and build a new simpler amp around those parts in a fresh chasis: the transformers, tubes and sockets and the amp board.

Now my question.. is it possible to rewire the two triodes of the ecc83 as two gain stages and then run it to one of the ecl 86's in the power section?

And if so, is it possible to wire a gain pot? The radio obviously only had a volume one, treble, bass (and stereobalance which i would remove bcs i do not intend to use it as a stereo amp).

I do have a full schematic and parts data sheet. But I am seriously considering just using the ecc83, one ecl86 and just point to point wiring it bcs there is a lot going on the original pcb and there are leads and switches all around the place bcs of the multiband radio receiver..

I know I should probably just buy brand new parts for a simplified princeton or whatever but at the same time I would like to give new life and purpose to this old junk which has been lying in the attic for decades. And I do want to build from these parts bcs I know it sounded pretty good considering its age and state and the fact those werent even guitar spekers. Login to view embedded media
Here is the maintenance manual with the schematic of the radio at the end http://www.oldradio.cz/schemata/ts538sn.pdf

Hi everyone. Having built 3 Lang 20W class A amplifiers, after finishing the 4th, during the final measurements, the dc offset is 7mV at the right channel and at the left is -25mV. In all the previous amplifiers the offset voltage was between +5 to +13mV. The only difference among them is that instead of +-20V regulated voltage supply, +-28V unregulated power supply which I think it is not a big deal. My worst problem has been in matching the BC560C. i have bought 100 of them and their Hfe was below 600 except of 2. So While all the BC550C were from 600 to 612, I have placed the only 2 BC560C with Hfe 600 at the differential amplifier and the rest where it has been needed to. The quiescent current was set for 2A as per the instructions of the article. I use separate toroid transformers with 2 separate secondaries 2 X 20VAC/8A and 4 X 6 X10.000uF so every negative and positive voltage use 60.000uF each. All the components have been purchased by Mouser except the BC560C. The output waveform are clean and undistorted at 1Khz/4V input from the wave generator. Do you think that those difference will affect the fidelity of the amplifier and if yes how can I fix it? Check the attached files for every helpful detail. Thanks a lot in advance.

Hello.
Need help for CAMBRIDGE AUDIO AZUR 650A Amplifier.
Amplifier is in Protect mode.
CAP5 protect led blink 4 times which means
shorted speakers,but no speakers connected to Amplifier.

Please help me where I need to control.

Regards

I hope I posted this in the right place... I was trying to build a portable speaker. My budget varies but I didn't want to go crazy. It started out as a simple idea... build a speaker box that I could plug in my Qudelix 5K to have the awesome app and equalizer. I didn't care if it didn't sound "great"... My goals were: 1: Try not to spend more than necessary. 2: Don't make it TOO big, I wanted the biggest speaker to be no more than 4 inches if I could help it. 3: I wanted to separate the highs and lows between two speakers, A tweeter and a woofer/full range, with a crossover. Added: 4: I realized flat 20hz to 20,000hz was NOT going to happen, so I decided I wanted it to have around 60hz to 19,000hz on a relatively decent flat overall response curve, made more difficult as most Woofers I looked at had a bit too much fall-off around 100 to 80hz. BONUS: 5: Use 4ohm speakers for power efficiency.
I tried to learn what I could browsing many forums and actual build guides.
Looking at Ohms I saw things like: "Make sure the speakers are the same Ohms as the Amp or you will blow the speakers or burn out the amp," or "The speakers can be a higher Ohm than the Amp but they have to be the same as the other speaker," or build guides where the speakers' Ohms didn't match at all.
Looking at Wattage I saw things like: "Match the RMS wattage of all the components," or "Make sure the wattages of the speakers are a bit higher than the Amp so the Amp can't blow them," or "If the speakers' wattages are too high compared to the Amp's then they will stress the Amp."
Looking at Sensitivity I saw: "The ohms and wattage don't matter, it's the sensitivity of the speakers that matters, match that instead," but on some build guides I saw, none of that matched either! I saw things like a 20w RMS 4ohm 90dB 2.83V/1m Tweeter being used with a 50w RMS 8ohm 80dB 2.83V/1m Woofer!
I'm incredibly confused! I spent several days looking at Speakers and Amps trying to just match everything so I don't have to worry about any of it, but that being very difficult isn't even what has stopped me... It's my realization that I'm in way over my head! I'm obviously either missing something or overcomplicating it... I just want to know how to match a Tweeter to a Woofer with DECENT accuracy and not blow anything up...
...
Now with how expensive the parts are that match in ways similar to those above, I'm considering doing a mono Amp with only 1 Tweeter and 1 Woofer for now and eventually building a second later splicing them together by feeding each the split left and right signal... or using two Bluetooth transmitters, each with a split left and right signal out of my Qudellix to each of the Satellite speakers.

No longer needed.

I’m Looking for a pair of ATC-Sm75-150
Eu preferably
Please, PM if you have a pair for sale.

I could be interested as well in one single unit of ATC-SM75-150Super

Best

Having examined the data sheets of 18 sound’s comp drivers in recent days, I’m intrigued by the fact that depending on the 8 or 16 ohm version, there are notable differences in the frequency response, with a tendency to more accidents and decrease in the UHF region for the 16 ohm versions.

The impedance curves also tend to exhibit more accidents with several maxima.

Only explanation I came up til now is that the 16 ohm versions involve a greater distance between core and diaphragm (due to longer moving coil??).

Anyone can comment on the above?

A lot of modern music players allow you to search for EQ presets for different headphones based on tests ran to make them sound more neutral.

For example, with Plexamp I can search for my IEMs and grab an EQ preset from oratory1990.

Can Moode do this?

Hello, I’m new to this forum but found it while searching for thoughts on repairing an MX5000 amplifier. My issue started out as loud uncontrolled low frequency noise coming from the sub. I thought it might just be too much gain on the sub so I went to turn it down a bit. I got more of this noise when exercising the gain potentiometer so I thought it might be the issue. It showed as an A50K potentiometer so I ordered what I thought was a replacement. Turns out it was a B50K but I figured it was ok so I soldered it in. Well, it didn’t work and I found/ordered an A50K. I took out the B50K and soldered in the A50K and now I’ve got nothing. Occasionally I get some weird noises. I took it apart this evening just to look over everything and I don’t see any evidence of electrical damage on either of the circuit boards. I connected all the wires back up internally and and plugged it back in. Then got some chattering noise with no audio inputs. Hooked up audio inputs and nothing and the chattering has gone away. I do get a low frequency hum if I touch both the positive and negative terminals on the low level audio inputs. Is the amp dead? Is there anything I can easily check? Can I put some sort of steady state resistor in the place of the pot to just check it? I’ve learned that I can get a replacement plate amplifier which will probably solve my problems. However, I just want to make sure I exhaust all my options before doing this.

Thanks for any help that you can provide.

Here is a fast approximation of a 6th order I'm building,
where the middle baffle and outer walls are set in stone and cannot be moved. But the baffle can be sawed, partly...

So to convert this into a properly working 6th order I have to "steal" space from the rear chamber to the front chamber.
But there is a port and a brace in the way, making the opening to the "stub" smaller than the outer/front port.
The stub opening would be 900cm2 and the port would be 1000cm2.
Now the question is, will this stub have it's own resonance or somehow otherwise affect the front chamber loading?

Hello,

i made a guitar amplifier. But i have a problem. I add a video and schematic link.

video : https://drive.google.com/file/d/1UWhGdim6vpIAbIJum5EPUE7MTuyZL0RR/view?usp=sharing

schematic: https://drive.google.com/file/d/1ybwzHHtpqFBV5gKnsvlcSiusPlCdJg0P/view?usp=sharing

mail : snkmuhendislik@gmail.com

Hi, last week I finished my fifth pair of electrostatic loudspeakers. (see attachments #5 and #6) I think it's the best effort of my five attempts.

Sensitivity is around 86 dB / 1m / 1 VA / 1 kHz. Outer dimensions are 40 cm x 150 cm. Diaphragm (mylar) thickness is 6 micron and dimensions are 23 x 130 cm. Stator / membrane spacing is about 1,6 mm, a little less than I used in previous models. (about 2,4 mm). I'm aware this limits maximum excursion, but has the benefit of improved sensitivity. I use a custom made 1:125 full range quality setup transformer.

I use loudspeaker screen on the front because otherwise the panels don't fit esthetically with my room. This dampened the fundamental resonance frequency with 5 dB. After fitting a mesh damping screen with a rather low rayle number on the rear stator (on the inner side of the wire stator in order to damp resonances in mid range as well), I got around 2,5 dB more damping, resulting in 7 to 8 dB damping. Resonance frequencies of both panels are 62 and 76 Hz. I guess they will lower a bit after breaking in. I hope they will stabalize around 50 Hz.

I used the software "esl_seg_ui" by Edo Hulsebos to simulate / calculate the electrical segmentation. (see attachements #1)

In the simulation I included the 1 Ohms series resistor between amplifier and audio transformer.

I did extensive listening tests in the room where I built the speakers which is a smaller room than my living room where I put them after they were finished. Bass extension was ok in the smaller room, but in my larger (26 square meters) room at greater listening distance (5 meters from speakers) it feels a bit thin. Not too bad, but I would like to have a bit more lf extension / power.

For frequency and impedance measurements, see attachements #2 and #3.

Instead of building another, larger pair of speakers I was thinking about adding an extra panel per channel which serves as a bass panel to improve bass extension. By putting two panels per channel close to each other airload increases resulting in lowering of resonance frequency. So I'm considering to build another pair with same dimensions and use the same amount of wires (64 per panel) and connect them to the other, segmented panels by adding 1 resistor which makes a low-pass filter. The only possible disadvantage could be that this lf segment is not symetrically on both sides of the main panel, but on only 1 side. Would this be a problem? I made another simulation using esl_seg_ui by adding this new panel by adding one new wire group of 32 wires (2x 32 in this simulation equals 1 new seperate bass panel of 64 wires). See attachements #4.

Included attachements:

#1: segmentation simulation for current panel
#2: impedance and phase measurement in REW, using a custom 1:125 step-up transformer and a 1 Ohms series resistor
#3: frequency measurement in REW with microphone close to front stator (about 3 cm)
#4: segmentation simulation for current + new bass panel
#5: rear side of new panel
#6: front side of new panel

I am parting out a set of prototype speakers a friend had built for his recording studio. just as he got his studio finished. the landlord sold the building so these have zero use!!!

I have FOUR (4) Dayton Audio RSS265HF-8 10" Reference Series HF Subwoofer 8 Ohm these are currently $205each plus tax and shipping. asking $140 Each or best offer. $250 for a pair shipping not included, or buy all four for $500 and get free shipping in the USA! and these babies are HEAVY!

I have FOUR (4) Dayton Audio RS180-8 7" Reference Woofer. these are currently $70 each plus tax and shipping. asking $50 each, $100 per pair plus shipping or buy all four for $200 and get free shipping in the USA

I have TWO (2) Dayton Audio RST28A-4 1-1/8" Reference Series Aluminum Dome Tweeter 4 Ohm these are currently $42each. asking $60 per pair plus shipping.

or buy ALL for $750 with free shipping in the USA. may consider offers.

all drivers have zero play time on them. but some woofers have some white paint on the rubber surround. should clean off easily.

Located in Minnesota. Please PM me for details

I'm looking for a better processor for my unconventional active 4 way speaker project. I am currently using the Peavey 48VSX, which has the main features I'm looking for, but I am finding it is fairly noisy for a home environment. And it would help to have a few more inputs, whether by having a single unit with more inputs, or two units that can be configured together.

The noise I'm experience is signal noise, and also the fan is very loud. I've actually unplugged the fan, since none of the components appear to need active cooling.

My wish list is:

Rack mount--1RU ideally
4-6 Balanced inputs (XLR?)
8 Balanced outputs (XLR?)
Low noise
10+ parametric EQs per channel (Including high pass, low pass, shelf, etc)
Matrix programming, delays, etc
Expandable (I might go multi-channel at some point)

My budget is going to be up to ~$1500. Hopefully less, but I don't expect to get something for nothing.

I got the idea to build a large, DSP controlled 3 driver 3 way speaker by using a 18" woofer (namely the Faital Pro 18FX600). The midrange driver needs to be used from 400 Hz, otherwise it's distortion is high. My initial problem is the 18" seems to resonate/distort if I run a sine-sweep in free-air mode. My Eminence Kappalite 3012LF doesn't acts like this. But recently read somewhere a similar problem, and when the 18" was secured to a baffle/box, the distortion had gone.

The 18FX600 is a relative low Mms 18" with not too high Le, so I thought it may be usable up to 500 Hz, where it not beams yet, according to the factory off-axis response.

Does anyone have experience with large woofer free-air distortion that gone away when the driver is secured to a box?

I tried the smaller brother 15FX560 which have very good reputation amongst builders and that woofer also sounded distorted in free-air.

Any replies appreciated!

These QFET Fairchild products are all gone very soon FQA28N15,FQA30N30,FQA30N20
every used any of these in design , get as many as you can afford.