I am doing a passive to active conversion, 3-way using a Hypex Fusion amp with DSP and while I am doing the box building I am also looking ahead into how I will set it up.
One thing I am not sure about is how to I apply a gentle slope to the overall response, e.g. Harman curve. For example, if I wanted to apply a 0.5dB (or another tilt) per octave roll off from 200Hz upwards to 20kHs.
Crossover points will be, say, 300Hz and 3kHz.
I need to use the overall EQ function (not per channel), right?.
But is there a way, in Hypex Filter Design, to apply a slope of a certain tilt to everything above a certain frequency?

Which are your favourite Bach's cantatas?

I replaced the rotten, deteriorated surrounds foam surrounds in a subwoofer with rubber. 2 x 8" drivers in a 22 litre cabinet? I didn't expect a room-shaker but the results are disappointing.
Any ideas, tweaks?

any one ever repaired this amp? the low voltage section?

I have 6 quiet channels, that are same med reduced output , not distortion just same level output
1 channels is normal level louder than the rest,

visual inspection there is a small chip in the low voltage section of the power supply board that has the marking :
CHN
LM358N
k3Y751

some resistors around this chip, and one leg of this chip have solder joints that look a bit overheated.

Considering buying this chip and replacing. Thoughts?

DSD DAC is an architecturally better DAC than R2R

As shown in the picture below, DSD DAC has the opportunity to achieve higher resolution and faster settling time than R2R DAC, so DSD DAC is a better DAC than R2R Dac in terms of architecture.

Click to expand...

After years of research and development, a DSD fully balanced DAC was finally developed. Under the R2R architecture, he uses the ratio of 2R/R, a weighted output decoder. Under the DSD architecture, the resistance is directly output. In other words, the R2R DAC draws a line according to a single point, which has relatively large distortion, and there is no good way to test the impedance brought by the switch, so the accuracy will be greatly affected. In contrast, DSD DAC is connected to a line according to multiple points, so the accuracy of DSD DAC is much higher than that of R2R DAC. Specifically, in a DSD DAC, a fully balanced channel has 64 resistors, which is equivalent to 64 bits or 64 points, while single-ended has 32 bits. R2R DAC is 24bits at most, but many have only 16bits. Therefore, the single-ended resolution of DSD DAC has surpassed any R2R DAC. Based on the above-mentioned differences in architecture, DSD DAC has the opportunity to surpass R2R DAC, and with unparalleled advantages in details, momentum, etc., DSD DAC is the truly best DAC architecture, not R2R DAC. Of course, the final hearing effect of DSD DAC is still limited by the quality of resistance and power supply. Therefore, under the same DSD DAC architecture, the quality of resistance and power supply is used to distinguish.

In order to pursue the ultimate performance, the flagship model of A&C’s DSD DAC, in terms of resistance selection, we choose the American RA non-inductive fever resistance. There are ordinary and pure silver resistors to choose from. The sound of pure silver resistors is more delicate, loose and soft, with Extravagance. In terms of digital processing, the decoder adopts the 4th generation JUN-level digital processor. The processor is modified to a fever-level processor customized according to the requirements of the JUN level. It has powerful computing capabilities and can compute DSD signals up to 120MHz. At present, most DSD signals do not exceed 15MHz, so there is a great possibility for later upgrades. In addition to strong computing performance, the most important thing is to perform FIFO processing on the DSD signal, and to reshape the input data to output a square wave waveform close to the theory, so that the time distortion is reduced to a minimum. A&C's DSD DAC can output a strong current, up to 30ma. Currently, there are fewer manufacturers concerned about this concept. The digital signal also has requirements for the circuit. It is like adding the previous stage to the system. The output large current can easily drive the decoding chip behind, so that the sound will be more natural and transparent, and the output signal has ultra-low jitter. Distortion is further reduced.

In the I/V part, A&C's DSD DAC uses a non-negative feedback design, which has better sound processing. Common I/Vs are designed with feedback, which will compress the sound and reduce the details, but the design is simple. The output of IV uses the American JENSEN output transformer to make the sound more musical. You should have a deep understanding of the output that has been used well.

Hi, has anyone tried this amplifier with Klipsch Heritage series loudspeakers?
I've a pair of Heresy, and I would like to know if anyone has tried it with this kind of speakers.
Thank you

I've never really torn down a modern phone but wonder if it would be possible to get better LF response out of a common phone by driving the screen and back with a bipolar voice coil. If it could be better enough to warrant the difficulty in rearranging everything..

Please someone experienced for help.... I have a problem with the quiescent current on one channel... With the VR 103 trimmer (I checked it and it's fine).. I can get a maximum of 0.9mV... I also changed the zener diodes d122 and d123 but there is no result. Otherwise, I made a complete replacement of the capacitors and the device worked... it plays but I can't regulate the quiescent current on one channel... The voltages are present and ok... Does anyone have any ideas?

Hello everyone!

I'm currently restoring Yamaha CX-1000. But i made one big mistake.
Disassembled SW701 (Rec. out switch), cleaned...and forgot default position of the movable part. Now it's working strangely. Was unable to find any photo on the internet. Does have manual, but i have trouble decipher output code table.
Maybe someone will be able to help me? Almost restored this nice preamp (all that left is to repair SW701 and replace motor in motorized volume control).

With all respect,
Alex.

I'm addicted to HI-FI and I love bringing old things back to life... I have no experience in repairs so I would love to be a member of this community if someone could help me if they know....

Hello! I Have an issue with my Yamaha PC-2002M amp and hope some of you guys can help!

For the past few weeks, I've been experiencing an issue with my the amp, which I use to drive my Tannoy SRM 10b speakers—my main monitoring setup. The amp is set to 1, and volume is controlled via my mixing desk.

Every now and then, channel B drops precisely by 5dB (this is also visible on the meter). To compensate, I have to set the volume on the channel to 6 to maintain a balanced sound. Sometimes, it may return to normal out of blue, requiring me to reset it back to 1, same setting like the channel A. Sometimes it gets to normal the next day when turning the amp on again. It also happened once that, when listening at higher volumes, the level returned to normal on its own.

Does anyone have an idea what might be causing this or know of a possible fix? Taking it to a technician requires making an appointment, but the issue is inconsistent—it depends on whether the amp is acting up at that moment or not.

Thanks!

I need to replace a damaged D28AF tweeters (movers, ugh!).
I will replace both tweeters, and option to buy more of the same tweeters for a center channel and surround speakers.
These tweeters are paired with Dynaudio 17W75 in a sealed 18-liter enclosure, with an 18db low pass and a 12db high pass Madisound crossover at 2500Hz.

I really enjoy the linear frequency response, imaging, off axis sound and sound stage with this setup. In my experience, piano music is the true test of quality, and these Dynaudio tweeters are beautiful.

Any suggestions are very appreciated.

I built a pair of SLOBs a while ago (and have since changed the drivers to a pair of Lii Audio Fast 8s) - and have been playing around with Dirac on my miniDSP SHD.

I was running the Pass ACN with values suitable for the SLOBs but have since recreated the curves digitally in the SHD via biquads and am using the SHD as the crossover.

When taking measurements, would there be any benefit to cover the rears of the drivers so that only the front wave is used for correction?

My thinking being that OBs do have issues with bass, but otherwise with an appropriate baffle, not really an issue. By blocking the rear wave, would my impulse measurements and corrections then be more accurate?

I was thinking a cardboard box a bit larger than each driver with some mineral wool inside loosely covering each driver - absorbing the sound from the rear but not affecting the response in the way a sealed box would, or at least not much.

This would just be for measurement, then I'd get back my regular sweet sweet OB ambiance once done measuring and take them off.

I've never seen this discussed, so figured I'd ask before spending a chunk of time on some arts and crafts.

Thanks for any wisdom-

Pete

Only $110USD

https://www.audiosciencereview.com/.../fosi-audio-box-x5-phono-preamp-review.59982/

Hello;
I was wondering, for my next 3-way active speaker system, focusing solely on sound performance, which would be better: a MiniDSP Flex Eight, or an audio-PC (fanless i7), a MOTU UltraLite mk5 audio interface, and software like Equalizer APO / CamillaDSP - REW?
Thank you?

Hey Everyone in the DIY world!

I had the idea to build a low roofed shed at a small outdoor wooded venue where I throw edm events. The dancefloor space is roughly 40x40 with a wooden platform at one end. I will upload a picture if I can find one that shows the space well. I have drawn a few diagrams to help the visual learners such as myself on here. Last event we threw in the fall resulted in a neighbor noticing their windows shaking about 2000' away from where I have my space (new windows may solve the issue). My set up last year was 2 Keystone Subs by Welter Systems with B&C18SW115-4 powered by XTi 6002 and 2 Yamaha DB12 PA tops. I figured my problem was the long throw capabilities of the keystone subs, and close property line. This is a rough diagram of the layout from last year.

My initial thought was to learn a lot more about sound processing and see if I could figure out a cardioid set up on the opposite side of the dance floor. The property line on the other side is much further from any structures with more trees and hills to disperse the sound. I have never been to a club or venue with rear arrays so Im assuming this is unusual and I should move the dj table leaving the platform as a viewing space. This idea is represented in this next drawing.

The area I feel most experienced in the DIY speaker building processes is in the woodworking side of things and less so in the engineering/numbers side of things. I have help from a friend with my speaker set up and DSP settings, but its not my area of comfort yet. With that in mind I was already thinking of building a low shed to put my speakers and amps in during events to keep them dry and less dusty. I was wondering if anyone cared to chime in on the idea of building a horn extension into my low shed using the roof, doors and ground. If I were to enclose my two existing subs into a low shed would that help direct the sound more than a cardioid set up with 3 subwoofers? Would the tolerances have to be super tight or would just putting them in a box make a difference? Below is a diagram of this concept.

Would putting a cardioid setup in a shed make it useless because there is a barrier blocking the sounds from emanating from the back of the shed. If I made rockwool insulated panels for the shed would it help block the sound from my neighbors in any appreciable way?

I know this is a lot of questions and I am pretty green in the technical side of things. I do have an excavator and can move dirt and build a lot within reason to make this a unique outdoor sound experience as my system grows. Please feel free to point me elsewhere or explore your imagination and help me make this happen.

Thanks everyone!! Y'all are the best

soon I will have a listening session to test a pair of RCA cables assembled by me.
Top of the range Marants CDs, Ampli + pre I don't remember the name (I'll update you later) but monstrous dimensions and weight and B&W 801 matrix speakers.

Hi, long shot maybe ... but I just finished repairing my TA-2600. Replaced the 2 belts. As of my usual habit .. I have 2 spare parts left over 😎... They must be from somewhere around/on the tape desk mechanism. I consulted the exploded views but can't seem to locate them. Anyone has an idea ? Btw .. The deck is working perfectly without them !

the bastards save space by recompressing old videos with the result being that all music videos that aren't recent sound like AM radio

those morons also aren't bright enough to differentiate between videos and music ... this from a company that is investing into AI

are artists supposed to reupload music videos every year so that there are 20 versions of every video each with its own comments links etc ?

the scary thought is the average person is even stupider than the ones that work for Google - luckily i don't often have to deal with average people.

i used to do cardio by biking on a trail that goes around Google and i swear all their employees looked like they have been dropped on the head a few too many times.

and Spotify is not much better. it set my playback quality to "low" by default even though i am on 400 mbit connection and premium plan. pretty sure i have set it to "very high" several times before. i think every time it installs update or i switch devices it keeps resetting to "low"

but at least with Spotify you can change it back in the settings. with YouTube they just keep sucking life out of old music videos and there is nothing you can do to stop those rat bastards.

I have the official Elektor Archive on a USB drive and am having issues with the main index page. A large chunk of the files (which curiously are those dated from 01/01/2000 (lol, millennium bug) report as not available. All the files are present and correct and all open normally if you drill down and find them manually on the drive.

When hovering over each title on the index I see anything with a 'US' (presumably as in USA) will not open. All the ones that open correctly have EN and not US in the file path. I tried remaining one as a test, but it doesn't work.

All titles open OK if opened from the root of the folder.

I'm asking Elektor over this but wondered if anyone else had come across this.

In image #1 you can see the file path in the lower left of the screen when hovering over a title. It is the ones with US in that do not open.

Hi all new to here, not new to audio, and always learning. I am about to re-cab a pair of Mission 760i's and joined to share and learn from comments.

i am sure you noticed that modern music has more bass than old music - this is in part because compact disc can produce lower frequencies than analog sources like vinyl and in part because class D amps can push more power into the subs than before ...

but that is not disturbing, that's good !

what is actually disturbing is modern music has less highs ... or are you just going deaf ? well it's both !

what used to bee "boom tss boom tss" is now is now just boom boom boom boom ... no "tss"

i used to think people got tired of the fatiguing sound of "tss" and it fell out of favor ...

but then i read an article about line arrays where the author suggested having a talk with your mix engineer to reduce the amount of HF because arrays struggle to reproduce it ...

what if HF in music is going down for the same reason bass is going up - because modern tech ( arrays ) prefers it that way ...

well it's disturbing for you ( or should be ) but not for me. if i am going to build arrays it actually works in my favor !

i thought i went deaf because i couldn't hear any highs in music then i listen to an old school metal track like this:

Login to view embedded media
( except not on YouTube where it is compressed the living **** out of )

and there is highs everywhere, so actually music is losing highs faster than i am losing my hearing.

they don't make music like this ( with highs ) anymore. not even metal. now it's just bass.

Hi:

Anyone can explain why this board with DIR9001 didn´t work in an Arcam Delta Black Box, with TDA1541A?

I have nothing more than pure silence!

Thank you!
Antonio

Are any of the tube magazines like Glass Audio, etc. available in pdf format anywhere for free? Would be handy to have them in electronic format. I have most of them in paper format so not interested in paying a second time.

Back due to demand! Again!

Please note that it can take a few months to get everything. Supply chain issues have made it take longer. Some have wanted different parts for that reason but the popular opinion still remains on preferring the very nice quality ones originally included.


5x20mm fuse option added for Euro buyers

So over the years people have asked about the old version, made by someone else.

It's probably time for an updated one. This one is a bit different. You may notice it does not have following capacitors after the choke. I have tried both ways, and my preference is without the following X2 capacitors. Also the capacitors prior to the choke are not varied in size because overall capacitance is more important - and they won't randomly resonate with each other.

The other major change is the addition of bypass resistors for the chokes. These don't ruin the filtration, but they do a good job of quieting the chokes that can get excited by different combinations of things on the mains.

Click to expand...

View attachment 1043981

Gen1 w/comoco's


Here's how it is different in settling time from the original.


Here's a comparison between resonances.

*2oz copper PCB (1oz is standard)
*Weco 983ZD terminals, copper alloy and can accept 2 wires for daisy chain. These are also safer, particularly if you use solid core wire that otherwise likes to make cold solder joints you can't see.
*X2 rated capacitors for safety, 4x 0.47uf. They are alternated for CFC (capacitor field cancellation).
*Discharge resistor for X2 capacitors
Coilcraft Comoco choke w/fuse or Bourns 8120/8121-RC choke w/o fuse & 15/16A/20A() max sockets
*Fuse clips are beryllium copper 3AG & 5x20mm options
*120/230v operation (parts & pcb)
*Mounting holes are sized to work nicely with M3 screws and standoff kits
*Size: 2.25x4.25in

Click to expand...

The Weco 983ZD are preferred terminals, but not always available as individual sale. For this reason I'm going to include them in the price of PCB, so that I can meet min order requirements for them and save everyone the shipping.

Price: $14ea ($10 per filter board, $2 per Weco, 2 needed per board)

Shipping: $11 US, priority USPS box
$20 CAD
$22 General international padded envelope (prices may vary due to a crazy world)

If ordering over 4x boards there may be an additional $10, depending on destination.

Need 32 filter board commitments to order.

sebbtp 12
birdbox 6
danbmellow 4
MtlJazz 6
skunark 4
jedibones 6
clsidxxl 4
jam econo 4
ElliotA 12
utownsquash 6
ItsAllInMyHead 6
rickmcinnis 6

Click to expand...

​

I am looking to output both balanced and single ended from a differential mono DAC (AK4499EXEQ) output after en I/V conversion while degrading quality as little as possible. I want to use an op-amp based circuit to do this, however, information on keeping both outputs is hard to find. Having one or the other is much easier to find documentation on. If you have any book recommendations or schematics to share, please do!

The circuit is the front end of the Pass A-40 with a CFP output stage. Powering up with VR1 all the way up, all the voltages match per the LTSpice sketch. However, once I touch the output with the signal generator positive (or any metallic object) the bias current jumps 500mA. The output sine wave is thick and zooming in shows a 4Vp-p 4MHz clean sine wave.
Apart from being fat, the output sine wave is normal as the level and frequency is changed. This is the same with any changes to the bias.

Rearranging Q7, Q8, Q9, Q10 to form an EF output stage (with a 150R between Q9e and Q10e) does not change things. However, removing the drivers and connecting Q7b and Q8b directly to the VAS results in a clean sign wave and square wave with no ringing for any bias current. The output is normal with input voltage and frequency changes up until the negative clips at about 10Vp.

I tried base stoppers 4.7 to 10R for all the output transistors. I changed Q5 from a KSA992 to a BD140. I tried KSA1220 and KSC2690 for Q9 and Q10.

The pcb is 100mm square with 4 layers -- signal top & bottom, power on 2 and ground on 3. Output and drivers connected by wires to the pcb, Q7, Q8 on heatsinks with a fan. The grounds from the board to the power supply common goes through a 10R resistor bypassed with a 0.68u Wima. The PS common is lifted from earth, the scope probe ground is not used and the only path to earth is the signal generator negative.

I pretty sure my test setup (3CH PS and signal generator, both Instek) are not the problem because I have built the Hiraga 30W Class A and there were no issues with proper grounding, etc. Appreciate any help or insights as to what I think should be a simple design.

Links to Modulus-86 build videos on YouTube: Post #2499.

matt_garman went through the Modulus-86 Build Thread and compiled a list of build pictures. You can find his list here: Modulus-86 Build Thread - Post #4463. A nice and compact Modulus-86 build is shown here: Modulus-86 Build Thread - Post #5213.

Getting all the holes in the right spots on the chassis can be a challenge for many. Here's my suggested method: Modulus-86 Build Thread - Post #5215.

Update 10 OCT 2021: Rev. 3.0 released. This revision represents the first major design revision since Rev. 2.0, which was launched in 2015. You can read more about Rev. 3.0 here: Post #2480

Update 16 MAY 2019: Tweaks to the CM cap connections to the THAT1200. The Modulus-86 boards are now made in Canada.

Update 30 DEC 2018: I completely forgot to add Rev. 2.3 to this revision history. That's remarkable as Rev. 2.3 was released nine months ago. 😱 TI finally decided to kill the LME49710, thus Rev. 2.3 uses one of the opamps in the dual LME49720, which is still in current production. The unused opamp is connected as a buffer with its input grounded. Rev. 2.3 uses all current production parts. You can find the product description and measurements here: Neurochrome :: Modulus-86

Update 10 SEP 2017: Modulus-86 is now in Rev. 2.2. TI brought back the DIP version of the LME49710. In Rev. 2.2 I switched back to the DIP version of the IC as some builders found the TO-99 version harder to work with. This reduced the BOM cost by a few bucks too. In addition to this change, the DC servo was updated to reflect the lessons learned from the development of the Modulus-286 while shaving a little more off the BOM cost. The Modulus-86 Rev. 2.2 provides the same stellar performance as Rev. 2.1. To order PCBs, please visit the Modulus-86 Rev. 2.2 product page: Neurochrome :: Modulus-86 Rev. 2.2.

Update 14 APR 2016: Modulus-86 Rev. 2.1 is now available for purchase. The main updates are: Changed LME49710 footprint to TO-99 to address Texas Instruments' decision to discontinue the DIP version. Slight improvement in THD near clipping. Complete rewrite of the chapters on power supply and heat sink dimensioning in the design documentation. See the release announcement in Post #2115.

Update 24 FEB 2015: Modulus-86 Rev. 2.0 is now available offering improved performance. See Post #838.

This spring I set out to design the Mother of All LM3886 Amplifiers. An amplifier so good that it would knock your socks off. But also an amplifier that someone with decent soldering skills could build if provided a well-designed circuit board. This design effort took a while and led to an interesting investigation of the capabilities of the LM3886. It also led me to produce an LM3886 design guide: Taming the LM3886 Chip Amplifier, which I will keep adding material to as it becomes available.

The Modulus-86 is my latest amplifier design. It is a composite amplifier using an LME49710 precision opamp to control an LM3886 power amp. The performance of the resulting composite amp, both in terms of measured performance and in terms of sound quality, is dominated by the performance of the LME49710. Hence, the performance of the Modulus-86 is absolutely stellar. One of the many benefits of the composite topology is that the power supply rejection is very high. This means the Modulus-86 performs as well on a real power supply (I tested with a toroidal transformer, rectifier, and 2x22000 uF) as it does on a regulated, $1200, lab supply (I used an Agilent E3632A). The excellent supply rejection is also one of the main contributors to the stellar sound quality of this amp.
In addition to the LME49710, an OPA2277 precision opamp is used for the DC servo. The use of a DC servo avoids the use of large capacitors in the main signal path.
The input to the amplifier is provided by a THAT1200 differential receiver. This makes it possible to use the XLR connections commonly found in pro audio. The THAT1200 provides performance rivaling that of an input transformer. When using differential connections, this minimizes the induction of hum and EMI, resulting in dead quiet during quiet passages in the music. The differential input can also be configured for use with the single-ended RCA connectors commonly used on prosumer audio gear.

The key features of the Modulus-86 are:

• 65 W (4 Ω) and 40 W output power (8 Ω) using a Power-86 with the recommended power transformer.
• Ideally suited for multi-channel amplification.
• Ultra-low 0.000061 % THD (1 W, 8 Ω, 1 kHz).
• Ultra-low 0.000067 % THD (40 W, 8 Ω, 1 kHz).
• Ultra-low 0.00038 % THD+N (40 W, 8 Ω, 1 kHz).
• Ultra-low 0.000067 % THD (65 W, 4 Ω, 1 kHz).
• Ultra-low 0.00041 % THD+N (65 W, 4 Ω, 1 kHz).
• Ultra-low 0.00069 % IMD (40 W, 8 Ω, SMPTE 60 Hz + 7 kHz @ 4:1).
• 0.065 Hz ~ 85 kHz bandwidth.
• 14 V/µs slew rate (fully symmetric).
• 84 kHz full-power bandwidth.
• 33 µV RMS output noise (20 Hz - 20 kHz, A-weighted).
• 42 µV RMS output noise (20 Hz - 20 kHz, unweighted).
• Differential input with 90 dB CMRR eliminating ground loops in the signal path.
• Phenomenal power supply rejection ensuring consistent, high performance even using unregulated power supplies.
• Elaborate use of planes and copper pours to maximize circuit performance by minimizing supply and ground impedances.
• Low-inductance signal ground connects to power ground at one point only for maximum performance.
• On-board Zobel and Thiele networks for maximum stability even with capacitive loads.
• On-board EMI/RFI input filter and ESD protection.
• On-board low noise voltage regulators for the driver op-amp and DC servo.
• Power and output terminal blocks accept wire sizes up to AWG 10 (5.2 mm2).
• All leaded. Easy to solder. 90 × 70 mm board footprint.

The THD+N is constant versus frequency throughout the majority of the audio range. The THD+N does rise slightly towards the high end as the loop gain of the amplifier rolls off. At normal listening levels (<1 W), the THD+N is perfectly flat versus frequency, resulting in incredible sound quality.

The differential input makes it super easy to use multiple boards in a bridge, parallel, or bridge/parallel configuration. All that is required to turn a stereo amp into a mono, bridged amp is that two wires are swapped. No component substitutions necessary.

The Modulus-86 has a gain of +20 dB (10x) for better gain structure in the end system. Should a higher gain be desired, the amp can be configured for +26 dB (20x) by changing a resistor. The circuit support the use of the THAT1203 and THAT1206 for gains of +17 dB (7x) and +14 dB (5x), respectively, should lower gains be desired for further optimization of the gain structure.

"But, but ... how does it sound?", I hear you ask. It sounds fantastic! The first time I turned on the Modulus-86 and started the music, I went “WOW!” before even making it to my listening chair. It was immediately obvious that this amp was something special. What struck me was the level of clarity of the reproduction and the deep quiet during quiet passages in the music. Talk about a huge dynamic range! I have played a few instruments in my life – including the trumpet and a brief stint with a drum set. It is especially important to me that metallic instruments (brass wind and cymbal for example) sound metallic and natural. This is an area that challenges many amplifiers and where the Modulus-86 really shines. The midrange is open and natural. The bass is precise and tight. What can I say? I really like it… The detail reproduced from Dire Straits, “Brothers in Arms” and “On Every Street”, for example, is out of this world. I am certain the incredible sonic performance is due to the stellar supply rejection and flat THD+N vs. frequency of the Modulus-86.

For those interested in more background information on composite amplifiers, I suggest reading the article, "Composite Audio Power Amplifiers" in Electronics Now, Nov. 1992 (pp. 38-44). This DIY Audio thread contains a few pictures from the article: composite amplifiers

For the impact of layout on the performance of an LM3886, I suggest looking at this DIY Audio Thread: http://www.diyaudio.com/forums/chip-amps/252436-lm3886-pcb-vs-point-point-data.html

Finally, for a more complete picture, I'll direct you to my Taming the LM3886 page: Neurochrome.com : : Audio : Taming the LM3886 Chip Amplifier

Thanks,

~Tom

I've got a Carlsbro Scorpion amp and early version which is the same as a Hornet 45 apparently and there doesn't seem to be a schematic for this.

Anyway there has been two replacement resistors installed as they both burnt out so am looking for confirmation that they are the correct value, the ones in question are R32 and R31.

Does anyone have any original that can help me out?

Awhile back member Adason had a near-giveaway of dual stepped attenuators like the ones shown in the picture below (these two are from Adason). Unfortunately, these two particular attenuators don't have matched values, they differ at steps 1, 3, 6, 9 and 12. also, they step backwards meaning the highest resistance occurs at the far-clockwise position, which is fine by me. Anyway!

I would like to use two matched attenuators in a Balanced Iron Pre project. If anyone who picked up an attenuator identical to either one of these from Adason has one for sale, or wants to swap with me to create a matched pair, please let me know. Thank you!

red resistor values at those steps: 2R3, 2k, 20k, 200k, 2M
brown (Dale) resistor values at those steps: 0R5, 2k5, 25k, 250k, 2M5
remaining values written on the paper

Hi from Copenhagen. I'm doing live pro audio and studio electronics design and service. Rigth now deep diving into tape machine syncronization. Thanks for keeping this nice forum going!

Just a bad room. Cavities, one open end to the left, the right side wall is going to be too close. I've gotten the room calmed down reasonably well, but can't escape from the basic geometry. I can get the main speakers of the moment (Wharfedale P10) into a nice place for listening (marked with tape on the floor, L & R not oriented the same, but they sound rather transparent and clear that way), but when regular life takes over they have to move back. They also make for too wide a sound stage for the TV (I didn't expect) and don't like late-night low volume. I'm perturbed.

Rather than trying all the speakers, perhaps the experienced will have ideas. At most about 14" to the wall behind the TV.

Current options:

3" transmission line. These sounded OK before, clean, but small.

3.5" open back - suspect these won't work, they take a lot of EQ

Polk RT55 3 way (2 6" and a tweeter). They have an odd bass sensation, but perhaps I could do something. No port in back. They sounded better before with pillows behind them. They're really too big for the location.

Wharfedale P10. I'm tempted to nearly plug the rear-facing ports. Can this work? Or maybe dense pillows behind. Seems unkind.

Antique DCM Time Piece. These are small transmission lines that sound rather nice, but the drivers and old and cheap, really do well in there, but replacing the drivers might be an option. I'm not sure of everything inside, and substantial surgery would be required. They're mint, so I'm a bit reluctant.

Antique 6" Open Back with tweeters, bad drivers, small baffles, sound oddly almost OK, except the drivers are truly sucky old Radio Shack units on their last legs. I'm puzzled that they sound OK as far as back reflections.

New options:

I can make something. Considering 4" more or less MarkAudio or similar full range in something. Pensil. TABAQ. Folded Voigt. Not having heard all these designs, hard to tell which might be least sensitive to poor location.

I might just be whining. Oddly, my 3.5" open back with a sub and EQ sound the best, my desktops. There's nothing behind them for a long way. Insanely crisp and clean, transparent soundstage, feels like about 18" depth from just at the monitor and back. Kind of spooky. That's what I want in the main area of the room!

Thanks for sympathy and suggestions.

Guys greetings, I have a power to repair, customer says it was attempted after it first died but it seems they attempted the repair. However the parts doesn’t seems to be appropriate based on their arrangement. Can someone suggest power supply FETs and audio output FETs or a full or partial schematic? They had IRF540N in the PS and a mixture of P75N05 mixed batch in the output.

I just acquired a Proceed CDP. While obtaining the user manual was very straightforward, obtaining a service manual not so much.
Would anyone be able to help out?

HI!

I am helping my friend with Infinity Kappa 6.2i series II speakers. I was wondering if there is a need to replace non polar capacitors with a newer ones? Usually electrolytic capacitors get dry during age. Woofer cap is 146uF and 100V. Midrange has 47uF, 26uF and 36uF non polar caps. Speakers were built in between 1992-1996.

For me woofer sound really boomy and do not go lower frequencies. The woofer winds have been glued by last owner and the midrange has been replaced with an new another no name driver.

If someone knows how to get best of these speakers working with crossovers caps or changing woofer for better one please let me know. 🙂

Sonic Frontiers Line-1 Main PCB - Signature Edition

For Sale this gourgeous Sonic Frontiers Line 1 Main PCB, with supply, Tube preamp with balanced designed from input to output.

This is the heart of the original Line-1 preamp, and it is the Signature edition version with tons of upgrade, Vishay VTA-56 and Caddock resistors at key location, Holcos resistors for the rest,
Upgrade bypass MultiCap Capacitor, upgrade rectifier diodes, etc... It was the original Signature upgrade done at the factory. I got this PCB from a former Sonic Frontiers employee years ago.
I made the also the optional Headroom Headphone amplifier, with crossfeed. This PCB uses now NE5532 opamp, OPA2604 shown on picture were reused years ago in other projects.
This preamp has no output coupling capacitors, it uses servo. It would be safer to have a DC detector circuit to and mute the output.

This preamp was controlled by a processor, and needs just a few addition to make it fully functionnal.
This is how I was planning to make it work:
-Input selection done by a rear PCB with relays and rotary switch selector on front. I made the PCB, it is functionnal, all the remaining parts are included. It also includes the Mute relay
-Start up HV relay control and Mute relay control. I made a timer controller PCB, with leds driver, to start the HV after 40sec delay, and then un-mute the output. A front toggle switch is use to control the Munte-Un-Mute. The Multiple Led driver circuit shows the delays, Mute, etc. These leds can be installed on the front as well.
-The original Volume was done by two PGA2311 chips. I have the detailled schematic of this section, two options:
1) use two stereo potentiometers on the front, and control the volume this way, don't use the on-board volume chips.
2) The are plenty of Arduino controller using PGA2311 chips on the net, make your own controller and use the on-board Volume chips. I have the code, and PCB design for one if interested...
I was planning to make a controller but never got there, the simpler solution of two stereo pots can be implemented rapidly and the preamp will be fully fonctionnal
-Front Power On toggle switch to add.
-DC offset detect board to shut down output if the DC detect signal needs to short the output (MUTE) - just in case the output servo ever fails (never done)

So to resume the only parts remaining to complete this preamp are:
-DC offset detect board to shut down output if the DC detect signal needs to short the output (MUTE)
-Chassis
-Front Power-On and Mute Toggle switches
-Front headphone connector.
-Front dual stereo Volume pots
-Knobs.

This is a great preamp, and a great project almost completed. I have all the schematics, detailled Parts List, Silkscreen and schematics of the PCB I made.
So it is easy to complete by an experienced user. The Main PCB was tested and it is fully functionnal.
Too many projects, not enough time to do all them, sorry this one as to go as well...

I have the brand new set of 6 tubes available (EH6822) at an extra costs, tubes are new, used only for the preamp testing.

Kit includes:
-Line 1 Main PCB with supply, complete, fucntionnal, missing two volume chips, Signature Upgrade
-Rear input realys selection and Mute PCB, with front rotary switch, all parts, connectors, switchs,etc included.
-Headroom Headphone Amplifier PCB (with NE5532 op-amp, not with the opamp shown on the picture...)
-Mute and HV Delay with LED control PCB
-All documentation, schematics, BOM

Optional 6 tubes for the preamp Electro Harmonix 6922EH, brand new (31U$ each at Parts Connexion)

Asking 500U$ for the kit + Shipping + Paypal 3.5% fee (Just in parts, this PCB is worth way more than that...)

possible to buy the 6 tubes set as well for an extra 125U$ (more than 215U$ if you buy them...)

Thanks for looking
SB

I am selling off my extra amps and preamps that I have not been using in order to buy a new pair of speakers. I love this setup, but it needs a new home. The Amp is dead quiet with the preamp on my Klipsch Heresy IV which are 99db efficient.

Aleph JZM Amplifier

• Custom made chassis from repurposed heat sinks, perforated sheet metal/aluminum, and a Modushop Hifi2000 faceplate (all pieces except the faceplate and heatsinks were powder coated silver)
• Antek AS-4218 transformer
• 47,000uf x 25v capacitors used
• Quasimodo boards on the rectifiers
• Switches to flip between SE and XLR inputs

Zen Mod Balanced Iron Preamp

• 3 Balanced and 2 SE inputs
• One Balanced and one SE output
• DIY Goldpoint 4 gang stepped attenuator POT (it's either 20k or 50k, cannot remember)
• Modushop Hifi2000 Pesante 2U chassis with custom faceplate
• Antek Transformers

I would like to sell both pieces together for $1500 and I will ship for free anywhere Conus... I have shipped these larger amps before and I plan to double box and probably ship both items separately with insurance.

Thanks for looking. If you need more pics, just ask.

The formula to calculate the THD of a system when the voltages of the first few harmonics are known, is this:
Where:
a) THD is the harmonic distortion
b) V2, V3, V4, ... are the harmonics voltages starting from the second harmonic
c) V1 is the fundamental voltage.

HP comes in a big difference of impedances.
I like to know what impedance your headphones are.
The phones you consider as your major.

For myself I have phones with 32 Ohms.
Many earphones are 16 Ohms.
Sennheiser have 300 Ohms phones.

Hello,

Im currently trying to fix my Orange Terror Bass 500w which has faulty Fqa28n50. They go short right after i turn the unit on. It takes the 6.3a fuse but also the 2 mosfets....
I attached the schematic, it uses a ir2153. What i dont get is when i power the ic with 12v, i have my gates acting on my mosfets but only a 15v amplitude oscillation.

I check everything on the psu and everything look ok so i might be playing with fakish component either the driver or the Mosfet...

What do you think could go wrong ? Its obviously on the primary side, it goes bad with no loads.

Cheers

Hi all, I'm going to breathe new life into a Heathkit W4-AM amplifier, that my Dad built in the late '50s. At some point in the past, and for reasons Dad can't quite recall, the original power transformer was replaced. The new Hammond (274BX) is similarly spec'ed to the OEM, just slightly lower HV at 375/0/375 vs the original 380/0/380. However, Dad noted on the schematic, along with the new transformer specs, that he changed the rectifier tube from a 5V4G to a 5U4G. No idea why... Given that the 5V4G draws less heater current, and has a lower forward voltage drop, would I be better to revert back? or is the higher current capability of the 5U4G going to make the amp more reliable? If you're not too familiar with this amp, it uses a pair of 6SN7's for the gain stage and phase splitter, followed by a pair of 5881's for the power stage. I won't be making use of the pre-amp power output capabilities (have a Mesa Studio for that task!). Appreciate any thoughts or suggestions!
Cheers, Dave

Join us at the Orchard Audio Open House and experience the future of audio, where every note and sound is brought to life with precision and passion!

• Date: January 20 (this is a monthly event, future events will be announced in this same thread)
• Time: Noon - 4:30 pm
• Location: 176 Franklin Ave, Rockaway, NJ 07866

What to expect:

• Live demonstrations of our state-of-the-art audio technology.
• Expert insights and Q&A sessions with our team.
• Refreshments and networking with fellow audio enthusiasts.
• Special promotions

Come and celebrate the beauty of sound with us! This open house is the perfect opportunity to get up close and personal with the latest innovations in audio.

Please RSVP to ensure we can accommodate all guests.
https://fb.me/e/1rUOfFlTS

Current Setup:
Source: PecanPi+ Streamer – $800
Amplifier: Starkrimson Stereo Ultra – $2650
Speakers: Soundfield Audio M1V2 – $2300 / pair
Cables: Triode Wire Labs
Room Treatment: GIK Acoustics

For more information please contact me here:
orchardaudio.com/contact or call 504-233-3444

Editor's Note: This is the thread for DIY Instruments and Amps - Stuff you or some other non-commercial person made!

For posting photos of your store-bought Instruments and Amps go here:
Post Your Pics of Store-Bought Instruments/Amps Here
End Note

Get a copy of the Grizzly Industrial catalog -- seems that the owner is zonkers for hand/home made guitars -- Grizzly is the source for cutting tools, end mills, boring tools etc., but there is an entire section in the catalog devoted to guitar construction Shop Tools and Machinery at Grizzly.com

Hi,
I have two enclosure as shown in the diagram below


There are 14 wires (16AWG) that will run from enclosure 1 to enclosure 2 (enclosure 1 has all the power supply).
One simple way to do this would be to drill holes in both the enclosures and run all the wires from enclosure 1 to enclosure 2. The problem i have there is that enclosure 1 is then coupled to enclosure 2. So if i wanted to work on either enclosure independently it becomes a headache, as i'll have to always keep both of the eclosures together.

Is there any solution by which the wires from enclosure 1 can be kept detachable from enclosure2? That if i want to work on either of the enclosures , i can just detach the cables like IEC inlet ?

Thanks.

This is my first high power class AB amplifier . Its performing good , the only issue I am having is the static pop or spike noise from speaker when I touch the chassis or ground with a metal object and it doesn't come when I touch it with bare hands . I am having only line and neutral in my home I have few amplifiers from brands , they didn't make any pop or spike sound .
I have tried disconnecting the tone control board and problem disappears but when I connect it again then problem comes back . Please help me to solve this issue

I am currently trying to install my system in my new truck but am running into a brick wall when tryimg to find access through the firewall for my 4ga power wire. I have a 2019 GMC Sierra Denali 2500 Diesel, way different than my 1500 which was a piece of cake. Anyone know of a good spot to go through? Thanks.

I have one PCM1704 that I know to be original and genuine, three more that I don’t know.

Anyway, price for all are $100 + shipping at cost.

R

Back in June of 2023 it was decided that Tubelab Inc would cease operations at the end of 2023. My wife Sherri who is half of Tubelab the corporation is still strongly in favor of the dissolution of Tubelab Inc. The long term operational fate of Tubelab Inc. is still undecided, however for the time being board sales have resumed. In order to meet the requirements of being a Florida Corporation, I now have to rent a Florida business address where a person is present during "normal business hours." A friend whose address I had been using closed down his operations at the end of 2023 leaving Tubelab Inc "homeless" so I found a suitable reasonable cost solution for 2024. The Florida Corporate status has been renewed. We will see how it works out.

I can't figure out how to edit the title of this thread. If it can be done or requires moderator assistance I need a "NOT" before the word ceasing in the title.

Tubelab Inc. is still here and shipping boards. Stock got low so I bent the Tubelab credit card severely. This was the result, ample stock of all boards is in the house:


George

I've bought a supposed NOS Metcal MX500, now I have it the psu buzzes quite loudly, is this accepted as normal?

Hi everyone, I joined the forum last night because I was searching on how to repair my Benkson TR5 transistor radio and came across Mooly's post.

My interests are cb/ amateur radio and cars, I am no electronic expert but have dabbled in cb radio's over the years.

A bit history, I found this TR5 radio on ebay and it was exactly the same as the one I had as a child so bought it however it doesn't work, Mooly kindly sent me some photos of the inside of his radio so I can check the wiring as mine seems to be missing some, fingers crossed it will be as simple as that.

I will keep you all posted if this works.

Thanks again Mooly I really appreciate your time.

Daryn (2327)

Newby question... I'm redrawing the Andrea Ciuffoli PSE 300B "reference amp" circuit so I'll have an "as built" drawing as I go along. I want to use Coleman regulators instead of the AC heated 300B's in the original schematic. Posted below is the original schematic and my work-in-progress schematic. My question is in red on my schematic, would someone help me complete the 300B circuit to ground so I can draw it? The original design used AC heating and returned the tube to ground via the CT of the filament transformer.

Work in progress schematic:





Original design:

Thanks to System 7 for his recommendation of the Monacor HT-22/8 cone tweeter and one of his suggested crossovers. I've been curious about this tweeter but have held off since they are not available in the states. I decided to take the plunge and order from a German dealer on ebay and was very pleased with the service. I used the Steve's attached crossover with the Monacors and a couple of whizzerless old Radio Shack 40-1354 I had laying around. I compared Steve's 3rd and 4th order
XO's for the Monacor and found the 4th order more to my liking. Here is my budget special using plywood found at the curb and old growth pine for the front baffle. They sound really good. No measurements because I can't do that but, really pleased.

In two-pole version this connectors are to find here (formerly Otto Heil)
http://www.hifizubehoer24.de/Heil-3017-Netzstecker-2-polig
In use on brands like Revox, Roland,
the datasheets (now from Schurter) are here:
https://www.schurter.com/de/datasheet/typ_3017.pdf
https://www.schurter.com/de/datasheet/typ_6075.pdf
https://www.schurter.com/de/datasheet/typ_6076.pdf

But in 3-pole version (go to the attached files) I don't find the exact naming. Even not by this supplier:
https://www.wittnercinetec.com/epag...WittnerCinetec-Super8-16mm-Film/Products/4092

Thank you very much for your information.

P.S.: last image show a version with additional centering resp. guide rails.

A month ago I was contacted by Brandon at the DIYAUDIO forum. He had seen my post on Krell Amplifier repairs and asked if I am able to help repair his Mark Levinson No 20.6. One of the monoblocks was experiencing a fault and and kept tripping and shutting down the amplifier.

I said sure. Little did I know that I was embarking on the most challenging task in my last fifty plus years experience in tinkering with amplifiers.

It is going to be a long story and I will start updating this post moving forward.

Hi all,
I bought a dusty Hafler DH-220 last year and am finally getting around to working on it. When I purchased it, it had crackling sounds on the right channel, but worked.

I knew it needed the electrolytic caps replaced, and figured that a new set of transistors for Q1-Q6 was a good investment. I got them from ebay along with a power supply capacitor (and bridge rectifier) upgrade. Those seemed to go fine, so I powered up on a DBT (all went as expected) and set to biasing. Left channel went as hoped, but the right channel is totally unresponsive. It measures .009 ma and turning P2 has no effect.

I've read many of the same problem from other folks here, so i started pulling resistors and diodes to check values (and replaced all with new units). R1-7, & D11-14 were all pulled and replaced. All were fine, but oddly R5 and R6 were 560 ohm, not the 1000 ohm shown on my parts schematic. is this an update?

I have checked R22-R28 in circuit, and they look to be in spec, but have not pulled them.

I have pulled all my voltages to compare to the voltages listed in the service manual. It seems all the small signal levels are off (rail voltages and ground are expected). I made a pdf with both the transistor voltages and the voltages at all the terminals and test points.

What am I missing?

Hello to all!

Hello!

New website for the sale of tubes, capacitors, sockets and everything necessary for valve equipment. We upload products from our large stock daily. If you can't find something, please ask.

Fast shipping and stock of Wima capacitors. JJ Tubes, Electro-harmonix, Sovtek.

Tubes and Parts

E-mail: info@tubesandparts.com

Thanks

So I'm setting up a PA system and I'm kind of confused. I have a berhinger europower p1500 amp. This amp is to be bridged to my subwoofer, a behringer e1800x. I'm imagining this is a very simple answer but it still is confusing me. To go from the amp to the speaker am I required to have a balanced (trs) cable? I have the speakon for the amp wired to +1/+2 but then to go into my mixer I require a 1/4" connector. if i am using a TS cable would that not be putting power to the + terminal (tip of the TS cable) and then also power to the - sleeve which is the ground? isn't that a textbook short circuit? does it work like this or am i required to have a balanced TRS cable? I am very confused.

Also, once it goes from amp to mixer to speaker does the speaker end also need to be wired +1/+2 or does it stay +1/-1?

thanks so much for any help.

Hello again! some time ago purchased this cd player with the usual broken laser head stepper gear, I replaced it, but it's still dead.

When switched on, the motor that moves the cd rotates at full speed (or fast) and eventually stops, no matter if the cover is open or not, as if the closing switch is ignored, the lens tries to focus, but the laser is not perceived. There is no other head movement.

I notice that the R176 resistor gets very hot, I don't know if this is normal, however the resistor measures 327 Ohms which according to the schematic is 330Ohm which seems correct to me. The consumption of the single board on power on alone is 0.12A which seems a lot to me, around 1w for only the LCD?,

The voltages indicated on IC101, IC 841 and IC 871 are correct.

On the CD802 connector pins 1 and 2 receive about 1,7v if we act on the SK130 switch (door switch).

Is there any way to know if the laser is damaged? I think there is no replacement now if it is damaged. Any help is appreciated. Thank you very much!

It strikes me as very odd how almost everyone wants feedback from me these days - even my bank now asks me for transaction fb when I buy things!

Anyway, hello peeps from the forlorn UK. My main electronics interest is not audio but vintage calculators (early 70s), but having decided to treat my niece to her very first 'proper' hi fi (compared to a smart TV and sound bar) for her 18th bday later this year, I had the idea to graft one of those android car head units onto a vintage amp I have, to make it 'cool' and also be able to talk with her cellphone.

But I might have to forget that idea - the vintage amp I had in mind is a Metrosound ST20 which I bought for £10 in 2011, and I only bought it because it was made in the town where I grew up and now live in. My main interest these days is local history.

Well, I had always assumed that the ST20 was bargain basement, but on a fresh surfing of the waves to start my idea off, that seems not to be quite true and I now can't bring myself to cannibalise it! Instead, I might restore (recap and possibly reswitch) it, try to add more separates (I just grabbed a very poor condition companion 8-track deck on eBay), and one day donate the system to the local museum... if they can find room for it.

My surfing brought me to the ST20 thread on this forum, and it was so interesting and potentially useful that I decided to sign up to express my gratitude. I must give a special thanks to Mooly the mod... I might just be coming back in a while to ask for more insight into the schematic Mooly! Old calculators rarely have any sort of audio capability, and those that do are best not mentioned here!

Cheers, amplifryer

I have some very large heatsinks for sale - see photo. They measure approx 32 x 30cm and the longest fins are 7cm long. They weigh 5.5kg each. I do not have a dissipation rating for them but you would have to be building a truly monstrous class A amp for these to be inadequate!
They also look really cool because of the curved profile of the fins. Price is £45 for one or £80 for two plus carriage. I have several pairs for sale.

Hello! Thanks for accepting me. I play the guitar for more than 30 years. I am a software engineer specialized in machine learning and AI with some knowledge on electronics and audio. I've been reading this forum for some time and hopefully I will contribute to this community the best way I can.

Variable inductance with frequency is something that occurs in all inductive loads, and without it, high inductance subwoofer simulations are very inaccurate. Woofer Tester Pro has a way of measuring variable Le, and simulating it is possible with their software. With that and with the help of @Bolserst, Hornresp now has the function of simulating it. Bolserst posted a spreadsheet on the Hornresp thread which can calculate semi-inductance/variable Le with frequency using impedance curves. With that, you can create much more accurate sims. Because of this, I will not simulate any speakers over 2mH of inductance without Semi-Inductance anymore. Here is a link to the spreadsheet: Hornresp - Page 851 - diyAudio
Here is a list of Semi-Inductance drivers:
Semi-Inductance Drivers - Google Drive

I'm adding my final updates to my Citation 2024 amp'

1. No change to the main PCB.
2. Speaker Dethumper PCB , Resistor R1 changed to a 200k pot by drilling two holes for the pot.. The cap C1 changed to 220uF. Time can be set from 48-0 seconds.
3. New Gerber rev 4 files for the speaker PCB with Gerber files is attached below.
4. Power supply PCB changed to rev 15. C2, C4 changed to 1000uF 500VDC. Added a terminal block to add a choke of desired. L1 Chole is a 1H 600mA.
5. Optional two VU meter panels are interchangeable. One is analog VU meters, the other is a LCD Touchscreen. Both are fed off the 12 volt power supply and the left/right signals from the main PCB. All files for both versions are available in this post.
6. Also include with this post are all the schematics, Gerber assembly, BOM and photos.
7. My only request, is that if anybody does try this project to let me know how it works out for you. You are responsible for your changes.
8. Did look into upping the power from 30 to 60 watts. Decided not to do after looking at the original amp and it's wiring.
8. The amplifier has been running fine since August.

Enjoy... Happy Holidays

I'm thinking of building this measurement amplifier having seen the reference to it in Self's Small Signal Audio Design.

I note that Samuel has kindly made gerber files available on his website but I was wondering if anyone had already ordered some boards and had any spare.

Thanks

Steve

Hello,

I've checked all the MOSFETS, inductors, diodes and filter caps and there's no shorts. I've removed the IRS 2093. When I turn the amplifier on, with only channel 2 high and low side transistors in and they're getting hot, I limit my PSU to 1amp hence why I think this hasn't blown up yet I think.

When all channels are populated with MOSFETS only channel 3 MOSFETS get warm, mostly the high side one.
Now with only channel 2 populated the high side is significantly hotter than the low side.

What could be the cause of this?

I'm helping a friend with his Quad am8/16 which is a mono amp used by the BBC to power one of their monitor speakers, we want to test it but need to make a lead up from phono to 3 pin xlr. I'm having a complete mental block of how to wire one up, can anyone give me a point in the right direction?

Hi,
I have a question about B2031a.
They are four potentiometer on the pcb - VR1,2,3,4.
All available from outside.

VR4 is input level
VR3 is bass speaker level ?
VR1 and VR2 are in HT part.
What are VR1 and VR2 doing ?
One is for HT level (VR2 ?), another one (VR1 ?) for 17KHz boost ?
Am I right ?
I just would like to reduce HT level.
Look at the attached crossover picture.
Thank you 🙂

Hi all,

For those of you who burn in your system/components I would like to mention the Cascade Noise Burn in sound file from TARA Labs.

It is an mp3 file with low to high frequencies continuously overlapping. IMHO a quite impressive difference using it, however, from a practical point of view please note that it can be VERY noisy so I would suggest starting out at low volumes (and maybe in general be careful with loudspeakers and headphones).

Download link is here: https://taralabs.com/media/cascade-free-burn-in-disc/

( ... not intending to start a discussion about whether or not burn in matters ... I reckon there may be many opinions about this ... )

Cheers,

Jesper

Hello everyone, I am trying to figure out why resistors R870 and R871 are burning out on the power supply board of the Marantz PM16. All connectors from the board have been disconnected, only the input power remains connected.

I bought the amplifier with regular 150R resistors instead of the original fusible ones. 😳 These don't burn out, but the ±60V voltages are incorrect. If everything is connected and the regular 150R resistors are in place, as it was when I bought it, the -60V rail measures -38V, and the +60V rail measures +25V. The 5V and 22V rails are correct. I have already measured almost everything on the power supply board. If I test it using a 100W light bulb, the 1.2R fusible resistor does not burn out.

Q854 (KRA104M on my board) seems suspicious. It measures strangely, but that might be due to its different internal structure.

Have you encountered a similar problem? Thank you.

Brought this a few yrs ago already built from a guy in Sweden has a few upgrades Caddock film resistors on out put and Auricap capacitors as seen in photos. I used this with a Khozmo stepped attenuator and it sounded really good. Looking for £150.00 plus postage or it can be picked up from Chichester West Sussex. Payment by bank transfer or paypal f/f.

I am trying to learn ngspice because it is open source and free. Unlike LTSpice I have to type the netlist directly as a text file which is boring and very prone to errors. Are there any graphical software tools I can use to graphically create .cir files?

What have I got myself in for?

The cabinet is 1,750mm tall, 550mm wide and 600mm deep. With 25mm thick panels of Euro birch ply, the volume is approx 480 litres, or 16.95 cubic feet.

Lovely Jarrah veneer, with Jarrah hardwood trim.

The driver is Lii's top spec reference unit, with this client receiving pre-production versions. Beautifully made, in polished chrome...very heavy.

Adding some quality Cardas terminals and solid core thin cabling.

With a low Fs of 28Hz, the cabinet has been tuned to 30Hz, using a wide slot-port.

Grill cloth will be a Marshall vintage style.

Should be fun.

I have around 1000 CDs collected over many years but find myself increasingly using streaming (Spotify and Apple) along with my vinyls. I am moving house, and SWMBO has intimated that they all need to go. What do you think? Keep 'em or ditch 'em?

Hi From Australia - Looking forward to contributing to the forum. Specifically wanted to join to add to thanks a member who posted a thread which helped me fix up an old REL acoustics storm MK1.

I'm a 50yo electronics hobbyist (software engineer by trade) and want to say thanks for some of the incredible help and resources in this forum.

I'm preparing to restore a family Rock-Ola jukebox and so have been studying the schematic for about 18 months and learning every aspect of tube circuits I don't yet understand. I've now modelled the entire amp in LTSpice and feel like I understand enough not to kill it or me. Some of the posts on this forum have been incredibly insightful, especially the spice models.

I've registered so I can share my simulations and everything I learned along the way - could be a big post! Any tips on where I should submit that? (I guess Amplifiers>Tube.

thanks

As some of us quickly learned from this thread that Lii Audio (established in 2006) is not Lii Song (established in 2019) now it's easy to define the original manufacturer by a line of brand new Coaxial Drivers.

As a fan boy of Tannoy I'm glad the Lii Audio (not Lii Song) is now making not only full-range, but new BIG Coaxial Drivers.

In this thread I want to discuss their new line, please do not post here about Lii Song as they have been separated from each other due to war between two ex partners. This is why you will not find coax drivers in the Lii Song catalog.

I hope Lii Audio will continue manufacturing unique drivers and will be able to expand their sales internationally, at the moment you can follow them on instagram for updates.

If some of you will find any reviews or have personal experience with any of Lii Audio COAX drivers please post in this thread.

On Ali Express for international buyers at the moment I can see '12 inch (C1202) , also '15 inch (H1502) and even '18 inch (Lii Audio TRIAX 18 and C1802) models and they are working on a bigger size as you can read on instargam page.

Some of them are good looking units, but pricey! What about sound quality?

Been cranking rock and roll since the late sixties. With my 70th in the near horizon, I am dedicating this journey around the sun as a music renaissance for the ole man. Having just winged it for all these years, I am digging in deeper into the addiction and this time doing it right. Self study for the last several months, thank you all those whose posts have helped my understanding of the fine art of music reproduction. Sound measurement and the fine art of speaker building are my current educational endeavors.

Does anyone know how to remove the counter weight shaft from the tonearm , so that I can replace rubber bushing that is sagging. I see one grub screw in the shaft and two below on the round part of the arm, but not sure which area. Also, can anyone confirm whether they can be removed, because I see some residue that looks like glue. This is from a QL-10 that is in great shape, except the arm, and I would like to have it spin vinyl again. Thanks.

Hello.

Would anyone know where I would be able to get a replacement bulb (called neon lamp in the service manual, but no part number) for the power lamp on an HH Scott 99D amplifier? I have some LEDs, but the voltage across the connections for that bulb seem pretty high.

Thanks in advance,
Les