Hi there,
I bought a nice mid-woofers that have manufacture provided box volume and tube measurements. I would like to try to build my boxes with passive radiators instead a tube. My only question is should I keep the same internal volume when use those passive radiators?

I’m basically new to oscilloscopes….well I have used an old one like 10+ years ago for very basic stuff…. But yeh basically I’m new haha
I was thinking of getting an oscilloscope preferable a portable one a module type to plug into a pc, phone, or even a small hand held would be good as I do repairs at home also so portable would be great!!! I can repair most things without an oscilloscope but sometimes you just need one for in-depth faults etc.... I repair kind of everything (that I can… I’m no pro haha still learning; everyone is!!) but mainly audio equipment.
It maybe a stupid thought but one like this would be a dream!! Looks too good to be true probably cheap and nasty with basic specs haha 😱
I haven’t done much research yet as I thought to post this first to eliminate a lot of branches if someone can steer me in the right direction.

Any suggestions on which way to go? A good allrounder?

Hi,

I am looking for a few people to beta-test the vacuum tube modeling software I wrote (for my own use), to iron out bugs before I do a public code release. Basically, it can build Spice-compatible models and do simple bias point/signal analysis calculations from the traced tube data (either from datasheet curves or obtained elsewhere). See attached screenshots for examples...

It is developed on Unix platform, but as it is written in Tcl/C should be portable to Windows (any takers?). Documentation is non-existant at the moment.

If interested, email me at frolov@cita.utoronto.ca. Replies might be slow (sorry...).

Looking to sell my SB Acoustics Ara cabinets in satin white. Cabinets are sitting in their box untouched at the moment.
Selling because delivery of the cabinets took 3 months and in the meantime my plans have changed.

The cabinets come with the bass reflex port and insert nuts for drivers installed. The following parts are also included:

• Hex socket screws 4x20mm (for drivers)
• Countersunk screws 4x20mm (for terminal plate)
• Wood screws 4x16mm (for crossover)
• Stainless steel terminal plate
• Binding posts (black and red)
• Seal gasket for terminal plate
• Name plate
• Grills for tweeters and woofers
• Damping material

Looking for 450AUD/275USD + shipping

Hi!

For my next project I'm playing with the idea to make a bullet-type tweeter. The tweeter I bought (SB19-ST from SB accoustics) comes attached to a mounting plate but it seems to be easy to take that small 'baffle' of.

Are there any reasons not to do that sound-quality wise?

Kind regards,

Reinhout

I own some great cable but they are stiff, almost like TV antenna cables, it can be a bit annoying when trying to use it to measure on projects. Is there a cable >500Mhz that is flexible and maybe thin? Of cause do I not mind if the cable can be used for much higher frequencies is double shielded and so on, but that would also make the cable less to my wishes, do I think🙂

Godo day all.

I just built the APEX speaker protect circuits for my AMP CAMP AMP, but Im struggling to figure out the connections for these circuits. Could someone please advise on a schematic for it please. Image below is what I have built





Thanx for the absolutely great site.

Regards
Cedric

Hi,

i had some pcbs left, each 12€ + 1€ packaging + your shipping option, please only EU (customs declaration makes no fun!).
Cheapest way would be a padded envelope, that should be the lowest costs.


(Sorry the picture is a little distorted, please click on it)

Hi,
I'm going to power a tube with a heater current rating of 0.8 A, 6.3V.
The transformer I am considering has a secondary current rating of 2A no CT.
I plan to use a bridge rectifier and RC filter to produce DC at 6.3V.

Will the 2A 6.3 VDC transformer be sufficent to power the filament?
I have seen somewhere that the transformer current rating should be 1.8 times the load current when using a bridge.

I normally use a full wave for filaments but no CT in this case.

Hi folks,

I'm working on my second DAC project, and I've run into a problem working with the SRC4392. Maybe someone here has some insight.

I'm sending I2S from a Raspberry Pi into the Port B serial port, but it only works with 24-bit data and there doesn't appear to be a register option for 16-bit I2S. I could tell Volumio to upsample to 24-bit, but that kinda defeats the purpose of the SRC. Port B is set up as a slave.

Background:
My first DAC was a simple PCM5142 driven via I2S from a Raspberry Pi. It worked well and sounded surprisingly good. It is compatible with the Allo Piano DAC driver, so I used that.

https://www.diyaudio.com/forums/digital-line-level/313760-starting-simple-dac.html

The PCM5142 seems to be happy receiving 16- or 24-bit data at any speed from 44.1 to 192 , but the SRC4392 isn't so accommodating.

The new one has an SRC4392 between the RPi and the PCM5142, with the DAC driven at 192kHz 24-bit by a better clock. I'm programming the 4392 from an Arduino Uno, thinking I might eventually add other inputs to the 4392 and make it a digital pre.

The format options for Port B (Register 05) are:

24 bit Left Justified
24 bit I2S - this works perfectly for 24-bit files
16, 18, 20, or 24 bit right justified

I thought 24-bit I2S would work with different data lengths, since it's MSB first. But no.

Has anyone made 16-bit work with the SRC4392 serial ports?

BTW, this forum is an amazing resource and a great community!

Thanks,
Peter

Sorry, I don't know if this is the right place to post it but I had to make a pick :-/

Alltime good guy and DIY speaker Guru who passed away two weeks ago after a kidney operation and then somehow contracting Corona... :-/

https://www.washingtonpost.com/nati...GuZeyg7BgS5Na6fd0SSC25vTTSiVFEWZDBjD4XsVIuoSI

Anyone have knowledge on this amp?
Yesterday there was 77v dc on the output but I applied a 4 ohm speaker and the voltage went away and it played music fine. Then I tapped the middle of the amp and it started to have static and buzz come out of the speaker. I instantly removed power and opened it up
There was a swollen cap 80v2200uf cap near the rca input that I replaced.
So when powered up with no load on the output there is 55v dc. When I applied a 4 ohm speaker it drops to 2v roughly.
There is 2 amps idle current with or without the load applied.
Also a little side note, without remote the protection light if faintly lit.

DIY FirstWatt Pass F5 power amplifier

Unit works perfectly

Build notes:
- DIY Audio Deluxe 4U Chassis w/ aluminum handles
- Primrose audio/SumR 500VA transformer
- Belden 89259 PTFE Coax cable for input wiring
- 16AWG silver-plated copper wiring throughout
- CMC gold-plated binding posts
- United Chemicon KMH 60,000uF, 35V power supply bank.
- Blue LED's on boards and power supply
- Mostly built to spec, except oversized 500VA transformer

Asking $800 shipped in the US.
Please consider that the DIY chassis + transformer cost $580 alone.

P.S life changes require full downsize of my system and projects, all of which I will be selling.

I have a set of FW F6 parts for sale, because I will never get to this project, and one of you guys needs this thing to distract you from the bat virus. $200.00 takes the whole kit and caboodle - shipping is free via USPS Priority Mail. Since the DIYAudio store is sold out of these parts, I can't keep this set without feeling guilty.

Here is what my price includes: DIYAudio Store PCB's and Transistor Kit (list price $80.60). Jensen JT123 Transformers (list price $75.00), Elna 1000 mfd/25V SILMIC capacitors, various resistors and zener diodes to complete the BOM from Digikey (list price $76.00). I bought diode values of 5.6V, 6.2V, 6.8V and 7.5V to match the MOSFETs, (read the article to understand why). I also will include a "Build Book" which includes all the documentation you need to build this wonderful amplifier.

If of interest, I also have a stuffed DIYAudio Power Supply PC board for use with two bridge rectifiers, AND two IXYS 600V / 68A HEXFRED bridges to go with it for an additional $50.00. This PS is fully compatible with bi-polar rail requirements like the F5 and F6. Shipping is free via USPS Priority Mail.

Hi, I just bought a a Pass Labs Pearl 1 from a very nice guy on this forum. Im using a MM 5.0mv cartridge. With CD I can only turn volume up to 9 or 10 o'clock and it is very loud. With Pearl/turntable I can turn it to 5 o'clock/ full blast and you can barely hear it. Previous owner had this problem when he switched from 150 watt solid state amp to a class D amp and thought class D didn't have enough juice to run phono pre. We talked on phone this afternoon and he experienced what I am. I know it's not the power of my amp it is something in the Pearl and previous owner agrees now looking back on it. Has anyone experienced this before while owning the Pearl. Previous owner is very willing to refund money or I send it back to him and see if he can fix it and then ship it back to me. If it's possible to fix it without shipping it back I would prefer to do that. I'm not the best diy guy but I do have friends that may be able to help if I could point them in the right direction, thank you for any help or guidance, Paul

When mating tube amps to cones...
Does the difference in tube amp physics V solid state render a different set of parameters?

Hello,

I have several inexpensive round plastic binding posts plates that come with cheap binding posts (Parts Express). I thought I would do a DIY upgrade by removing the metal binding posts, plugging the two screw holes, and drilling the flat plastic face to fit better quality binding posts.

Have any of you been able to source something like what is shown in the image that is just a blank, and isn't drilled for or come with the bindings posts? The Mundorf and other brands are well beyond my budget...

Thanks!

Joe.

After giving up on using my amp with 300B, I put the 6B4G back in and I noticed one side was somewhat weaker than the other. I figured it was one of the tubes not properly seated in the socket, usually it's the Russian driver tube because the pins are slightly narrower. I did my usual wiggling and it settled in place, then went out again. I went to wiggle the power tubes after and I noticed that one tube was much cooler than the rest. I used my new handy dandy IR thermometer that I've been using on everything, and are being used to take peoples' temps too in the age of Covid-19, and sure enough one tube measured 150F or so internally where its mate measured 250F. I checked the other pair and it was more like 220/230, so a better match. I also swapped the cooler tube with the hot one to see if it was something other than the tube but the cool tube stayed cool. And cool is relative, I wouldn't want to grab either tube.

Does this mean that the one cool tube is drawing less current and generating less heat and hence the other gets more? I know this isn't a direct measurement, but can I make this assumption? And how would I measure individual current with a shared cathode? Can I just measure with a single tube and then swap?

What got me started on using the 300B was that I thought I was going to need a new pair soon after one of the filaments crapped out a month or two ago, and I wanted to try something other than the Sovtek 6B4G. I had a spare that I used but it likely didn't match. I may be in that situation anyway.

It sounds as good as ever at the moment, when the driver isn't seated it sounds distorted since one tube isn't getting voltage on the grid and it sits at ground.

I have the following setup, Rpi4B-Volumio-Amanero-Acko Reclocker-TP BIII DAC and I cannot get the Amanero 384Combo USb input working to save my life. I have spent a lot of time trying the settings available in Voluimo and loading various versions of the 384Combo Firmware to no avail. Does anyone know how to get this to work?

I have managed to get my Windows PC to successfully stream DSD via Foobar,although it was a battle, I got good results using DSD-WASPI (Event).

If anyone can help it would be greatly appreciated.

Doing some "weeding" of my loose glassware and found a nice PX4 in a box. Tested perfectly for Gm and Ia on the VCM163 but when I switched from "Gm" to "gas", breaker flicked out and blue fault light lit up. Oh dear, too bad, never mind - time to bin it, but I was deeply suspicious as the PX4 showed no sign of blue glow when in the Gm test mode. Tried a new tactic - briefly turn the power off before doing the gas test. No grid current, no gas. no breaker : good tube. What could be wrong with my VCM163?
M

Hello everyone. I'm posting for two reasons. 1: trying to get some help with a minor issue on my Aleph J and 2: to hopefully learn something in the process.

I have built an F5 and Aleph J. Both amps have the exact same power supply parts, case and PS board from the diyaudiostore.com. The Aleph J has a 120Hz buzz in both channels when no inputs are hooked up. The F5 does not. Both amps work and sound great. Enough about the F5. Observations about the Aleph J:

1: The buzz is 120Hz measured by a frequency monitor and the very inexpensive scope I have. Approximately equal in both channels.

2: When a preamp is hooked up, the buzz quiets to the point you have to get very very very close to the speaker to hear it. This means normal listening volume you really are not affected by it.

3: Touching the shielded wires on the inputs increases the buzz.

4: Disconnecting the inputs from the PCB board has no effect on the buzz.

5: Shorting the inputs (hook + to -) eliminates the buzz.

6: Safety earth and the only connection to ground (through a cl60 thermister) from the power supply are to the same bolt to the chassis.

I'm assuming this situation is likely from a ground loop. Here is what I have tried to eliminate the buzz ( I realize some of this is not specific ground loop related):

1: Disconnecting input wires from PCB, checking for no continuity with the chassis on the inputs. Changed from a twisted solid pair to Cat 5. No effect.

2: Changing orientation of the transformer both by rotating and tipping up on its side. No effect.

3: Checking and rechecking continuity from the MOSFETs to the chassis. No continuity from any MOSFET to chassis when the power supply is disconnected.

4: Mains are run though the base mounting plate under the plate to the euro block shown in the picture. They are twisted the whole way. No effect.

5: Connecting the input grounds together has no effect.

What I find most curious about this is that the amp quiets when a preamp is connected. I'd like to understand this as much as fix the problem. The amp really does work very well and I know I'm letting my obsessive nature take over here. Any input or direction would be appreciated.

2 x Purifi Audio 6.5 drivers for sale.
Brand new, unused still in original box.
They were ordered for a project but there was a time delay in delivering so a replacement was found.
Very unique driver.
Cost over $900AU delivered.

Sell both for $550.

I'm curious about the design of the secondary windings and wonder if heavier gauge wire is in the four ohm section, or if multiple windings are used.

Also, my hunch is that the Paradigm Studio Reference 100.2 may be better coupled using the 4 ohm tap. Mine play plenty loud (105dB +) with solid bass. IIRC, they dip below 4 ohms at a couple points.

Hope this post is in the right spot with two questions. Thanks for any help.

So I found a Pace MP-1 desoldering station w/ SensaTemp SODR-X-Tractor Handle for $75 shipped to my door. I know that Pace is considered by many to be one of the best desoldering branded tools on the market and rarely do they show on Ebay in any type of working condition. I figured even if I can't get the desoldering station to heat up the tip, I can easily get my money back with just reselling that upgraded handle/iron. That is if the problem isn't in the iron itself (I really hope not), but based on the quote below, I believe the issue is in the desoldering station.

The seller stated: "Tested to power on. Suction appears to work. The tip did not get hot. The main station makes a rattling noise when turned over."

Click to expand...

I should have it by the end of the week and I wanted to go ahead and reach out for any info someone could provide if they have worked on this unit before. From what I can gather, this unit has not had any attempts to repair it once it stopped heating up the tip. I assume this because of the quote above, if they know something is moving around inside the case, but don't what it is; that makes me assume it has never been opened/worked on.

Opinions are welcome, even if you have never held this unit in your hands. The theory of operation of a normal soldering station should hold for any desoldering station aside from the vacuum pump. I figure another option is to get an affordable desoldering station off Ebay (station only w/o pen/handle) and use the MP-1's iron. This may obviously require some adapters/modifications.

I have been modding a power amp, mostly PS improvements(caps) and signal path resistors.

I decided to argument the power supply lines (lots of shelter in place time). The original supply lines from the main rail caps to the driver/output transistors is a series connected line of parallel runs of 23 gauge wire. There is at least 4 junctions points in the power supply path making the rail feed to the first transistor. I removed those 23 gauge jumpers, replacing them with a larger size wire to transistors. Also, since the supply to the drivers were on the end of this series supply line, I wired a separate supply path to the drivers.

I then tested the amp and there was an nice improvement in detail and dynamics.

While looking over this supply path I discovered that the output layout had additional quirks. Each channel has a push and pull section. The layout was different on each channel. One side had the output transistors in a series chain connection path to the output point like the supply line. That path had the series connection through several single 23 gauge jumper(short) connections. The other channel had (push) 4 output transistors set connected to a single pad, then through a dual 23 gauge jumper. The other 4 transistor (pull) path was a combination series/ parallel paths. All these differences due to a single sided board design limiting connection paths. There are also additional wire jumpers from the diode bridges to main filter capacitors.

So with time and curiosity (limited money investment) I started a major mod effort. I first connected (each channel) all push and pull transistors to the output point in a parallel path connection through bigger solid copper wire. Each transistor had it's own output path.

The sound became very detailed, the increase in bass output easily noticable. The only problem is it lost it's music appeal, at least to me. The top hats shimmered, the bass solid, soundstage better defined. The casualty of this change was the midrange. The overall sound (of my system and to my taste) lost its musicality.

This was a mod step I didn't like overall, and I removed the parallel transistor connection, returned to the original series output connection path but retaining the larger wire( sans the 23 gauge). The musicality return.

I have modded/played with many digital CD/DVD circuits and have a good understanding about the importance of layout in those devices, but amps? That is, discounting size and type of materials, the connection/layout matter more than I thought..... Now that the shimmering top end, solid bass definition is compromised, I feel the loss. Can't I get both that and the musical mids from this amp? Any suggestions. I don't what to wear out the screw mounting holes taking this apart another 10 times.

If low inductance is maintained, is almost any cable OK for powered subs? It seems that capacitance and the dielectric properties may not be too important - providing proper shielding is maintained in noisy environments.

I was given a set of kitchen mitts for Christmas
Amazon.com: HOMWE Extra Long Professional Silicone Oven Mitt, Oven Mitts with Quilted Liner, Heat Resistant Pot Holders, Flexible Oven Gloves, Red, 1 Pair: Kitchen & Dining
to replace some beloved old ones that had just worn out and didn't really work any more.

These long silicon mitts are much heavier and hanging them is a problem. The old ones I stuck key rings on and they thus stuck to some 1-1/4" magnets on the back of the refrigerator. The new ones drag the magnet down the refrigerator. I brought a magnet with a hook but same thing. There is not really an alternate spot to hang these
--> Need more powerful magnets!
But WHICH? I was thinking about raw flux and patterns thereof, and looking at SO many magnets on Amazon, sheesh. One says "adhesive backed" so thin double sided tape could help. Ideas?

So I tried this with my homemade amp a short while ago after getting some new 100k POTs that are linear type B ones since my original became quite scratchy and was cutting out from being a used part.
Put a 47k resistor from the middle POT pin to ground of it in my circuit and it performs surprisingly well.
Is it log? Hell if I know, but it does ride the volume up much more slowly until it reaches a point where ears and linear pots don't match and it ramps it up properly to my ears.

I made sure to first do a line load test and put a 47k resistor across the line inputs to my amp with volume at max and input set low and dumped the 47k across it and it didn't decrease volume level so there seems to be no issue with pull-down or impedance issues.

Curious how many of you have done this to convert linear volume potentiometers to pseudo log types and your experience.

For those lost to what I am talking about here is some essential reading in my opinion..
http://geofex.com/Article_Folders/potsecrets/potscret.htm

I performed a web search on the topic of this thread but found no information that applied, and knowing not only the generous spirit of the members on this forum but also the fact that many are experienced in various technological professions and are all around "sciencey" kind of guys, I humbly post it here in the hope that someone can shed some light on a most perplexing mystery.

I own a small two-wheeled truck of tubular steel construction with a small open steel platform at its base which rests and rolls upon two pneumatic rubber tires. It is the kind of cart normally used for transporting heavy objects such as large boxes, furniture, and appliances over short distances. In my area it is commonly called a "two wheeler". As the spring season wore on and the weather warmed the lawn grass began to grow again and I began my springtime outdoor chores. One of those tasks involved moving some items over the lawn with my two wheeler and a few days after doing so I noticed that there were yellow tracks in the green grass where the tires had passed over. I took notice but had little concern because as the grass grew the yellow portions of the grass blades grew upward with green portions of the same blades pushing up from underneath. The yellow portions of the blades were at the top where the tires had contacted them.

To the best of my knowledge the tires have never come into contact with any herbicide or other poisonous substance and the truck, which is about two years old, has never been used off of my property. I purchased it at one of the large home improvement stores here in the US. It was manufactured in this country, but the pneumatic tires, which appear to be made of a curious amalgam of normal rubber and perhaps vinyl, are embossed with a phrase that indicates their place of origin is a geographically large Asian country with a tremendous population and a large manufacturing base.

Could the tires present toxic contact to plants? I can think of no other explanation. I am not overly concerned as the effect on the grass was temporary and superficial, not systemic, and the green grass is now growing in the affected tracks and seems to be perfectly healthy. I myself have no intention of eating the tires but I will be sure to wash after handling them for purpose of inflation.

If anyone has heard of this effect from another source or could offer an educated guess as to the cause of the yellowing of the grass in the tire tracks which cleared to green as the grass grew, I would be interested to hear from you.

I think I may have found a topic that is fresh...then again nothing is new under the sun...so here goes.

Vented woofer boxes, to me, is just another horn style. The proper way to use a horn is to have the tuning note, which governs cutoff, a specific distance away from the lowest intended note played.....if I tune my 18" woofer to ~15hz, Decay and Group Delay are significantly improved even before adding damping material into the design, so much so, that it begs to question...are people purposely sacrificing SQ for spl? If I tune to fs 24hz, performance in the 30hz area is bad with group delay and decay, though much louder.

A separate issue; lets put a huge resonance on top of the woofers resonance...who thought that was a good idea! Decay is exacerbated by the lack of control the woofer has at fs! let alone tuning too close to the passband.

I am focusing on 30hz, but as we move the register decay/group delay is improved as well.

I've "upgraded" my 6B4G amp, a completely modded ST-70, to accept 300B tubes interchangeably. It uses the stock Dynaco transformers, the original choke in the power supply and the chassis. The driver board is a Curcio "premium" board that is spec'ed to use 4x6DJ8 as phase splitter/LTP, but I've been using 6N6P instead in the driver position. The main change with the power tubes is to remove the negative fixed bias and use cathode bias with 550R on the filament center tap. I also disconnected the negative feedback. Of course the UL tap just dead ends at the tube socket since the pin is open on a 6B4G. It really isn't hard to do the mod and make it work. The quad cap was replaced with a Curcio board that increases the capacitance with higher voltage caps and also nicely has bleeder resistors built in.

With the 6B4G tubes this amp just rocks, and can also play the soft stuff with finesse. I really had no complaints with it. And it has been stable too, no problems with it.

I modded it for 300B by removing the old unused cathode ground and the 10R resistor for the bias measurement. (the original I believe is 15.6R but you can't find them.) I then ran dropping resistors between pins 2&1 and 7&8. I wired adapters to take the heater voltage from 1&8 whereas the 6B4G uses 2&7. Each side worked when I tried it. So far, so good.

But what happens with the 300B in place is that when I turn up the volume one side drops out and doesn't come back when I turn it down. And not that loud either, just moderate really. (It is playing a lot louder than that now, We Will, We Will Rock You!!! So loud, but with the 6B4G). The PS is shared, so it isn't that. I have 2 theories. First, I don't have enough current to power both sides and one just drops. Second, the dropping resistors can't take the current through them. When I turn it off and back on both channels will play. And the 6B4G continue to work as always, so I haven't fried anything important. I haven't tried switching sides with the tubes but I'll do that tomorrow.

I'm also disappointed with the bass, but if I can't turn it up I won't get much bass anyway.

Any ideas? I get that I'm stretching an ST-70 beyond its limits so maybe I should just leave well enough alone and build a real amp.

Hello everyone. I come here to seek help in the design of a compressor with a focus on mastering. I have two 6DJ8 valves and one of the requirements of the project is to use one or both of them.

Before I start, I want to make it clear that one of my goals is to minimize costs, even if it means worse sound quality - I'm doing it because it's a grad project and also for learning, but I don't have a decent budget at the moment, and the logistics and component production here is very costly and slow.

I developed a basic prototype in LTSpice to simulate with .wav files, and managed to compress drum sounds pretty effectively, at least in theory. However, I have no knowledge of the real, practical aspects behind it, and therefore I would like to receive help from the forum folk.





Some important points I would love to have contributions:

• I want to avoid using transformers as much as possible (I know you can disagree with that, but tell me if it's possible to do it without transformers, or at least convince me why is it so critical/necessary).
• The LED-LDR (in green) group represents a makeshift Vactrol I made with heat shrink, where the LED excites the LDR directly. I measured the set and developed its equation, which is under the LDR in the schematic.
• I never saw an amp op buffer directly into the a compressor's input, therefore i feel in my guts this looks absurd in some way. Shed a light on this, would you?
• The 6DJ8 uses 130V max plate voltage. As I live in a place where the electrical network is 127Vrms, I intend to rectify the signal directly to supply the valves. I heard about humming. Can I do it?
• To supply the NE5532, I would like suggestions: switching source, voltage regulator... What is the most suitable solution?
• The output represents an old radio output transformer (2400:8) and my laptop as load. How necessary is the transformer? Can I get rid of it? What are the implications of directly connecting, for example, my phone in the input and laptop in output?
• I know mastering should be done in stereo. Can I just replicate this circuit for the Left/Right channels? Is there any (transformerless) other way?

Essentially: what works in this circuit? What is absolutely garbage? EVERY piece of information is extremely valuable. Feel free to contribute in any way. Thanks!

Hi,
At 64 with eye sight fading and shaky hands, I have had a go at my first pre-amp + phono stage since the late 80's. What a ball ache. Tried hot air gun and soldering Iron, but I am getting there, need tweezers and an eye class just to see the component. Went with SMD to keep size down as I only have free version of Eagle, hence modula design with many connecting cables...Just volume board to finish when parts arrive from Mouser.. Shocked at how much a few SMD resistors cost (thin film Vishy or Panasonic)..Hope images come out OK..







.

I noticed that QSC is producing a line of 2 or 4 channel compact (half rack) sized Class-D amps. Info:
I scoured the spec sheets but I could not find any mention of distortion at any level. This has me concerned that spec is not very impressive. Maybe these amps are intended for commercial use where that is not a critical parameter?

Since I like to build active speakers, half-rack sized power amps are of interest because they could easily be incorporated into or placed on the speaker itself while remaining unobtrusive. An example of this is the Parasound Zamp. There are also some compact, modern 2-channel class-D amps from various Asian sellers, but I have not found them to have a very good looking distortion profile. There are mono amps like the Emotiva PA-1, but that is not really what I am looking for. Feel free to point out products that might work in this application.

Hi

my home cinema is breaking down (it's an LG HX506DI which is blocked at startup with the message: "please wait") ... so I have in my pocession two speakers and a subwoofer that I would like re-use with another amplifier that I plan to buy used ... in the meantime I wonder if it is not possible to make an amplifier myself with the constraint: two kinds for the two speakers and one output for the subwoofer, a 2.1 input ...

Thanks

Hi just complete my Decware DIY SE84 amp and one side there is a issue.It plays ok for a second then slowly the volume falls to almost zero.I check the tubes,swapped tubes,cable,check the caps.Everything seems ok.The single driver tube by my tube tester indicates its weak.Could a single driver tube cause the inbalance of the channels volume?.

A brief look at some Parts threads in this Forum involving Crossover parts has taken the wind out of my sails.

I thought it would be a simple task of carefully selecting replacement parts involved ensuring quality:

Inductors:
Select air core 16 gauge pure copper.
(avoiding iron core, thin gauge low purity copper winding)

Resistors:
Select quality examples which are non inductive.
(Avoid anything sandcast, and use of magnetic materials.

Capacitors:
Select quality examples avoiding cheap electrolytic designs.

After reading a few Parts threads on this subject I'm learning that there are almost as many variations on parts as there are Speaker manufacturers and Speaker models.

A nightmare to navigate.

I know variations can encompass, personal tastes, choice of musical source, equipment and loudspeakers involved which will play a part in making a selection, not to mention actual testing of performance.

For the simple enthusiast who is just looking for best bang for buck speaker crossover improvement, but isn't particularly technical and doesn't want to sink a kings ransom, is there such a thing as "go to" Capacitors, Resisters, & Inductors, not to mention binding posts (free of iron), which can make a difference to the performance of ones Loudspeakers?

Not only brands to choose, but a reasonably supplier?

cheers

Cliff

Being looking at this board for a few hours checked all transistors and change most diodes

i marked the voltages i am getting at test points

could anyone take a look and send me in the right direction..

most of the voltages are twice what they should be see attached

thanks so much for any help

I found one, and now can't delete post.

Not sure if this is the right area to ask this or not,but here goes.
I have this little 2.1 amplifier

TPS3116D2 Class D 2.1 Bluetooth 5.0 Amplifier Board 2 x 50W + 100W with Filter and Volume Controls

and this power supply

Amazon.com: AIYIMA 24V 4.5A 108W Universal AC Power Adapter Laptop Charger 5.5x2.5mm,Audio Amplifier Power Supply(24V): Home Audio & Theater

that I plan on putting in this aluminum case

Senmod 120x114x33mm Sliver White Aluminum Power Amplifier Enclosure HIFI Electronic Project Box Case - - Amazon.com


The case is longer than the board and I want to add a 5.5 x 2.1 jack to the back panel of the case so I can plug in the power supply. The amp has + and - power terminals so you can add an external jack. I found the ones below but was worried that I couldn't use them because they will ground to the aluminum case.

Amazon.com: Lsgoodcare 10Pack 5.5 x 2.1 MM 5A DC Power Jack Socket Threaded Female Mount Connector Adapter with Dustproof Plug: Home Audio & Theater

Is that going to be a problem? There are jacks available with plastic casings as well, but most of those say they only handle 3A. Does anybody think that will be a problem using the plastic ones because of the lower amp rating? The board for the amp seems to have a pretty cheap plastic female plug so I didnt think the plastic ones would be any worry.

Thanks

Hi, this speaker only have a capacitor in series with tweeter as crossover. Someone here know the valiue on the capacitor?

Make a list. You probably can't get everything completed but it's a plan.
My list:
Three st70 chassis need to be rewired and tested.
Finalize tube hybrid design.(using only parts on hand)
Minimus7 speaker stands.
Combo guitar amp of my dreams.
Finish stereo plate reverb.
Learn how to play harmonica.
Finish quantum action at distance experiment.
Update password book again.
Build boombox with some of those $2.00 tpa3118 amps bought years ago.
Become proficient in f150 hacks using forscan.
Repair the stack of Marantz receivers collected.
Find better solution for music software, start re-ripping bucket library. (nursing home version)
Update the buried hard drives.(field trip)
Get ham station back on air.

This list is probably good for a 90 day pandemic.

Hello,
I am brand new to Moode Audio and very impressed so far with it. I have searched around but haven't found the different type of audio files supported. I have got it to play mp3 files with no problem, but wondering if it will also play flac files?

Thanks for the help,
Gary

Hi, I have some Class AB gear to sell. As a newbie, my eyes and pocketbook were bigger years ago. I will not be building the attached kits, boards, etc. Prices are marked at a good discount already, but all offers considered. Shipping is not included. Shipped from Western Canada.

Image 1: Destroyer Dx Super A w/coils
Image 2: Dx regulated PS.
I have 2 sets of these (2DxSA+1DXPS / set): $50usd per set

Image 3: My Ref FE v.1.05
I have 2 pcb: $30usd for 2 pcb

Image 4: VSSA amp module, components installed list, build guide
I have 2 modules: $60usd for 2 modules

Image 5: CFH9 amp Apex/xrk971/Sonal
I have 2 pcb: $20usd for 2 pcb

Image 6: P30ZF pre amp Apex/alexmm
I have 4 pcb (2 needed per preamp) $10usd per set of 2

That's about it for this advertisement. PM if interested. I will be advertising more gear also, so keep tuned.

Regards,

Myles

Here is a list of my components id like to use. Im not sure how well this pre-made 3 way crossover is but the 4500 cross with the tweeter seems good to me as with the rest.

Peerless 830990 6-1/2" GFC Cone HDS Woofer 8ohm
Peerless by Tymphany 830990 6-1/2" GFC Cone HDS Woofer
Peerless 830992 4" GFC Cone HDS Woofer 8ohm
Peerless by Tymphany 830992 4" GFC Cone HDS Woofer
Fountek NeoCD1.0 ribbon tweeter 5ohm
Fountek NeoCD1.0 Ribbon Tweeter
or this tweeter 7ohm
Fountek NeoCd3.0M-blk 3" Ribbon Tweeter - Round Flange - Black

Crossover
Speaker Crossover 3-Way 8 Ohm 800/4,500 Hz 200W
or
Eminence PXB3:3K5 3-Way Speaker Crossover Board 500/3,500 Hz

my other issue is wiring since the tweeter seems to be 5 ohm and the other two are 8ohm. Not sure how that will workout. I also wanted to build a center speaker with one more 6.5" driver.
Any help or recommendations on if this will work?

Hello everyone, hoping all is safe.



A friend of mine recently gave me a pair of HiVi F6 drivers which I plan on building powered bookshelf speakers out of.



I am looking for a good budget tweeter, preferable around or under the 30 dollar range. A couple of options I was looking at are the Morel MDT12, Morel MDT22, Dayton Audio RST28F-4, and the Dayton Audio DC28F-8.


What do you guys think, any suggestions?

Much appreciated

What is the measured voltage swing peak to peak on steady tone 1KHz needed to bring a push-pull 6550/KT88 pair of tubes in UL connection with A431 output transformer?


Power supply B+ is 500Vdc
Each tube bias at 50mA




Question arised from measurement of a mono bloc Dynaco MK 3 and pushing only 40 Volts peak to peak at onset of visible clipping, on 8 ohms tap with a resistor.
Should go near 60 V p-p ??


Driver stage is a Poseidon with new tubes 12AX7, 12BH7
Outputs clips before the driver stage shows clipping measured at the input 6550 KT88 grid.


Thanks.

Anyone else out there having problems with all this hand washing and using alcohol cleaners?
My wife gave me a bottle of Aveeno something or other and I can say it really helps but it is ridiculous how much I have to use.
Not usually a manly topic but it sure is now.

Anyone have a circuit diagram for this pre amp?
I have found a faulty diode and IC in power supply, IC is no problem TOP223, but the diode has no recognizable markings, it is Z something on pcb board.
I'm guessing it's a zener, but have no idea of voltage or wattage.

Im looking to recap my preamp with good quality capacitors that are readily available from Mouser, Digikey.
Any particular brands and models I should consider without breaking the bank of course, there are more than 40 in all.
thx

I'm looking to build a pair of floorstanding 3.5 way speakers with the following components and would appreciate any feedback.
My goals are some amazing sounding home theater floor standing speakers that will be used 50% for movies and 50% for music.
I have a Velodyne SPL-1200 Ultra subwoofer so won't need the speakers to give any rumble during films, but would like them to cover as much of the 20hz - 20khz range as possible as I like to listen without the sub for music generally.

I've picked Dayton Audio Reference drivers as I've been recommended them as brilliant quality drivers.

Tweeters: Dayton Audio RST28F-4 1-1/8" Reference Series Fabric Dome Tweeter 4 Ohm

Midrange: Dayton Audio RS52FN-8 2" Reference Fabric Dome Midrange 8 Ohm

Bass: Dayton Audio RS225-8 8" Reference Woofer

I've never designed a crossover before so any help would be greatly appreciated.

One of the hardest parts of DIY amp building, for me at least, is rounding up all the miscellaneous parts to make things work in my chassis.

At places like mouser, there are literally hundreds of thousands of these parts. I live in a remote area and don't have a place to go "look" at parts to figure out which ones I would like best.

So I thought I would start a thread to get input on your favorite miscellaneous chassis parts. There are no limits to what you suggest, but a few items that are always necessary. Would be nice to list the mouser or other location part numbers.

- power entry connectors

- power switches

- power fuses/holders

- terminal strips/blocks to mount on the chassis for various components like an NTC or other external parts.

- Switches of many different types, input selector switches, bias meter switches, etc.

- Meters for things like bias, other settings, power meters, etc.

- RCA connectors, speaker connectors, etc.


What are your favorite misc chassis parts? If I can get a good list going, I'll create a mouser project and share it out for others to use/copy.

gabo


I'll start off by offering this link:

Keystone Electronics Lug Terminals Terminal Strip Solder Terminals | Mouser

It took me a while to find these on mouser, but find that I use some variant of these on almost every project.

Hi everyone,

I looking for datasheets of PTO / PTO/2 / etc. etc. or SGS ATES 10337 because I should repair my vintage radios.

Thanks to all

I am playing around with some 12As in a preamp and i have noticed something odd:

I use a LM317T as current regulator for each tube (two separate LM317Ts plus separate floating PSUs). The CCS are adjustable so I set each one for 5V measured at the valve pins.

However current through both valves is 297mA?? I experienced the same with a 71A I plugged in...

Input to the CCS is 12V. The LM317Ts have ~4V across them so they are not dropping out. The voltage across the sense resistor (10R in parallel with 390R and a 1k pot) is 2.88V. Both filaments measure 5V

What gives? The spec for both 12A and 71A is 5V at 250mA....?

Looked around a bunch on here and think I have my answer, but just looking for confirmation.

I'm trying to make a pair of longish RCA cables to add a second zone to my stereo. It's going to run through the basement so I received Canare star quad cable as a recommendation to keep out the interference.

I read a couple of threads on here about how to construct these properly and have one last question.

Of the three wires, signal (Blue), return/drain (white) and shield (braid), which one do I leave unconnected at one end of the cable? I've read posts/articles that say the drain should only go one way, but most of what I've read said the shield should be the wire left floating.

Thanks!

Images of 6.5 for sale. Unused. $550pr. Cost of $900

Happy easter, at the moment unable to use search facility so apologize if already covered. Has anyone undertaken any upgrades to the Quad Artera power amp.
And if so did it release more detail and micro dynamics.

All,
if someone owns one or does know a potential source, any hint is appreciated,
Marcus

Admin: If this thread is located in the wrong section, please move it.

Alright, I am experimenting with some cable design and got to the part of measuring parallel capacitance (Cp) and realized I am missing some information.
When we read the shared information from cable manufacturers, Ls, Cp & DCR is often shared.

My question is this: I understand that Cp is measured between 2 leads with one of the ends open, but that is not what I am wondering about. Say you have more than 2 conductors (typical), each conductor pair has Cp.
Am I suppose to only look at the Cp between one pair or am I suppose to add all the pairs together ?

Ex): There are 5 conductors, which amounts to 4 pairs, so: Cptot = C1+C2+C3+C4

Many thanks in advanced.

Oneminde

Hello all! Hopefully this hasn't already been posted about, I couldn't find anything using the search.
I recently acquired a pair of OneAudio Studio Wireless M headphones by accident. I got them as an open box for super cheap and didn't realize they were a bluetooth model with no input jack. They were so cheap it wasn't worth shipping them back, and they actually sound decent enough for the price. I figured theyre good for when I'm doing homework and I don't have to worry about breaking them if I toss them in my backpack for school.

That being said, I'd like to add a wired option to them so I can use them if the battery is dead. I've never dealt with bluetooth so I was wondering if you could provide some help. I'm assuming the receiver must have output wires to the drivers that I could solder the jack to. What I'm not sure of is if I need to add some sort of switch to change the source, or if just having the headphones shut off when I plug them in would be sufficient.

I think this should be pretty simple to do, I'm just still learning about how electronics work so I thought I'd ask the pro's. I figure its also a good pair of headphones to play with since they were super cheap and if I mess something up I won't be out much. Thanks in advance!

Nice aluminum chassis for a headphone amp project.
My RJM Sapphire was in this chassis. PCB's are sold and I'm parting out the rest.
Chassis is in generally good condition, bottom has drill holes from previous project.
Front and rear panels by Front Panel Express

- Dimensions: 7W x 12D x 2.5H
- Front panel - holes for volume pot and headphone socket
- Back panel - holes for RCA. New IEC and used SPST fitted.
- Bottom - 3M bumper feet

Case costs around $67, panels another ~$50, IEC, SPST etc....

Asking $45 + shipping

P.S I haven't verified all dimensions but I think a WHAMMY with offboard pot can fit nicely

Even though it's not indicated in the service manual, both Cerafine 27000uf 50v power supply caps are bypassed with a 100uf 50v Cerafine cap. It looks original. 😕

Why are these there and does it really make a difference in sound? Should I replace these when recapping or leave them out?

JRC claims noise for it's NJM2060 quad opamp as 1.2uV RMS (RIAA Rs=2.2k, 30kHz LPF). How much is that in nV/rtHz?

In the attached photo, is "A" supposed to be connected to "B"? If so, what is the purpose of the round area between them?

If someone has a spare TPA3255EVM board, I'm interested in buying

Thanks

I've designed many complex digital layouts but never anything analogue and certainly not valve.

I've created a PCB layout for the RH84 design amplifier and would appreciate comments on the layout. I've attached two versions: the basic layout, and one with a ground plane copper flood - something that is routine for digital.

The layout is single sided with no jumpers needed. The heaters are not included as I would intend to wire these separately with twisted paired wire routed away from the PCB. The PCB size is 100x200mm which is the size of the blanks I happen to have available. All HT traces have a separation of at least 2.5mm from any other trace which should be good for 315VDC without solder resist.

All comments appreciated

Image1 — ImgBB

Image2 — ImgBB

First post here so, please, be gentle.

I have two April Music S1 stereo/mono power amps that had been humming along nicely for several years. The amps are based on the ICEpower 250ASX2 module. I've been using them since new in the mono configuration.

Several months ago, one of the amps started producing a horrendous noise when switched on. I was sure it was going to blow out the Esotar tweeter in its corresponding speaker. Thankfully, it did not.

I took the offending amp out of service and switched the other amp to the stereo configuration. That was fine for a while. Incredibly, about a month after the first meltdown, the second amp experienced the exact same failure!

With April Music out of business, there's no manufacturer's safety net in place.

Since so many forum members have experience with class D modules it seemed like a good resource to turn to for advice. While there is additional circuitry inside the S1 amps, I can't help but think the noise is most likely originating with the 250ASX2 modules. Is that a reasonable assumption? Replacing the modules would not be that difficult (expensive, but not difficult).

Yes, it is VERY curious that after years of service the two amps would fail within months of each other. Don't know what to say about that. I've replaced them with a pair of Schiit Vidars (in mono mode) and those amps have had no issues despite having been dropped into the exact same equipment setup as the April Music amps.

Any thoughts, suggestions, recommendations would be greatly appreciated.

I have the frame and magnet of this old 8 inch AlNiCo speaker that I got from I friend of mine. Its cone was destroyed so I cleaned it to rebuild it in the future.

However, I have a single one and I wanted to have a pair. And I'm trying to figure out what speaker it is to find a similar or equivalent one online.

Here are some pics:












As you can see its remarkably similar to Philips 9710, but it isn't a Philips 9710. There are some differences, as, for example, the fact it seemingly uses a brass demodulation ring (and in a different placement) and the "holes" in the frame are completely round, while 9710 had holes with flattened sides.

I remember the original cone (although damaged) it had a whizzer exactly like Philips 9710.

It has these numbers and codes behind: "KF 239" (with an indiscernible number ahead, but looks like a 10) and "326", none of which gave me any results.

This speaker was found inside one enclosure of a used stereo vinyl player, and I don't know if this is the original speaker. The speaker in the other enclosure was a different AlNiCO speaker.

It was bought in Brazil but I doubt this speaker was built here at all.

So, any ideas?

Do you think that If I bought an used Philips 9710 I could rebuild both to be reasonably matched drivers?

Thanks!

Firs do I have to tell that Mooly have already told me how to construct a power supply for his amplifier. What I am trying is to learn and understand the PSU thingy🙂
I do not learn by just copying and not understanding what is going on.



Let me start by telling what I think I may have understood.


1) A power amplifier do have a predetermined gain-multiplier, a multiplication of the input signal, that are the result of the construction and is not adjustable.


2) If the power supply's Voltage is less then (input signal x gain) you have clipping.


3) headroom do let the amplifier avoid clipping if the input signal, suddenly gets higher, due to suddenly change in input signal.


My question is first, is that right?


Second input signal x gain must have an upper "real world" limit, a limit for how high an input signal can bee?


If we take Mooly's amplifier, since that is what I am building for the moment. It have a recommended input Voltage of 45V p/p but what would 100V do (assuming all component can handle it) Would that give headroom, general higher gain or just stupid?


Please if you want, do try to explain it so even an dummy can understand it🙂

Does anybody know how to build one of these?

Having some trouble with this amp, when I give it +12 on the remote the amp tries to pull what I assume is excessive current. (I have my bench top power supply set to 3 amps.) The power supply will pulse on and off trying to build rail voltage but not achieving it. I never get a square drive wave on the gates.

I removed the rectifiers, the power supply no longer pulses and the amp only draws a little bit of current on start-up. There's a good drive wave on the PS gates at start up but it disappears very quickly and the current draw falls back to near zero.

The rectifiers tested OK; no shorts, not open, passing current in the correct direction.

One of the output FETs is no good, the other 3 check out OK on my multimeter. With the outputs pulled from the board and the rectifiers back in the amp returns to a state of pulsing, failing to build rail voltage.

The only components generating heat are the PS FETs which get warm but I also have not left it running for more than a minute.


Does anyone have a suggestion of where to look next? I was not prepared to find a TDA7570 driving the outputs.

Hi

The DIY speaker bug got into me about two year ago and, unfortunately, the more I read, I felt that the less I knew... Now with far too much time on my hands, I decided to give it another go. Yes, I understand that a 3 way speaker is much more difficult to develop and I would be better off with just buying a kit, but where is the risk in that 😀

Drivers used:

Dayton Audio DSA315-8 12" Designer Series Aluminum Cone Woofer
Dayton Audio RS52AN-8 2" Reference Aluminum Dome Midrange
Dayton Audio PT2C-8 Planar Tweeter

I tried to maintain a flat curve and an overall impedance over 4/5 ohms (my past attempts would just dip to 2 ohms or lower).

What I do not understand:

a. Regarding the phase graph.. Are the vertical lines supposed to overlap in order for the drivers to be in phase (I assume in phase electrically, as they can be out of phase depending on how I place them on the baffle)

I was hoping I could have your opinion regarding the crossover/ the feasibility of my design.

Thank you

I've got an amp project going on another thread here. In that project I want to use a TV horizontal sweep damper tube as a "slow start" device for the B+. Currently I have option "A" in that schematic. But I was thinking... if the purpose of the damper is only to give me a slow B+... Why the heck am I putting it right behind my silicon diodes? It can be anywhere right? So I drew up options B and C in the picture. I'm liking C the best but want to run it past. Moving the damper down the chain allows me to use a much larger first filter capacitor (option B). But then I thought why not get a lot more filtering capacitance by moving the damper to the end of the whole train? (option C). All options have the same number of capacitors, just in different places (MRC is motor run capacitor as I wanted to end the filter train with a film capacitor).

Which do you like the best? Am I way off on something here?

stuartmp said:

Thanks again for all that guy's. Just wondering if anyone has upgraded there output stage to a triple EF. There seams to be a lot of advantages to having a triple. No idea why the HD does not employ one.

Click to expand...

i have a badger TEF in the works, the VAS and the big CCS are adjusted for 5 mA idle currents....

I just recieved new from partsconnexion that they have sold out of black gate N 100uF 50v caps. This is very unfortunate as I was planning to build a parallel version of Peter Daniels gainclone (using his pcbs). I have a stereo version up and running and it is wonderful with the BG N caps - they were a big improvement to the standard panasonics supplied in the kit. Now I can't source similar parts and it seems that I will have to build a parallel version using other caps. It is rather frustrating that BG are discontinued as they really have improved the sound in my alephs, preamp and my DAC...

1.
Are there any caps that have similar sonics to the BG N cap?

2.
Would parallelling a BG standard with a smaller value of BG N or film cap be a good approach?

3.
Would it be possible to use 70uF instead of 100uF? As in one very big film cap. (so long for the small enclosure)

Thanks for any answers.

Hi guys,
I have this Memphis on the operating table. The symptoms are protection light and power light are both on. I pulled the outputs to see if protection light would go off, nope. I pulled driver board, no help there either. Pulled the power supply FET's, that wasn't the answer. Has anyone ran across this before?

I’ve made a very good 3eAUDIO TPA3255 amp with an analogue input and I am thinking of making something a bit more high tech next. I’ve done some some research into components and figured I could build this into a small case.

A tiny windows 10 pc with WiFi, hdmi and 2 usb’s.
5” Touchscreen
Khadas dac
Audirvana software or similar
USB SD card reader

I know I could get it to work but does anyone think I would be able to get the user interface configured to work well.

There`s lot of people using MicroCap for simulating circuits so I guess this thread will be useful..

1. How to measure Output imedance vs Frequency?