Hello friends. I recently bought a pair of Hammond 126C interstage transformers to couple my 6SN7/300B SET. Using the circuit attached, I am getting 63 Volts RMS drive for the 300Bs with a very clean looking waveform down to 40 Hz. This is way more than adequate for the 300B. My problem is that I am getting an ugly waveform on the amplifier output, which is originating in the 6SN7 driver stage. (I have proven the source by experimentation). The offending signal is about 15 millivolts P-P at 50Hz with a strong 3rd harmonic component. My line frequency is 50Hz, so I am tempted to think it is mains supply pickup. This ugly beast was not present in the output when I was using RC coupling. Has anyone else experienced this problem with the 126C? I'd very much appreciate any suggestions.

I have been modifying (and hopefully improving) some basic amps for fun lately. One was a Yamaha RS300 and a Rotel RA 930-AX(for a friend). Main improvement on both was increasing bias to abt 30mV between emitters. Anyway, that is not the topic here.

In these cases I wanted to measure channel separation, witch I have not done much, since many of my DIY builds have been dual mono, and maybe I have not considered it to be a significant factor for SQ.

What I found was that separation was pretty bad on both amps, especially on higher frequencies (around 40dB from memory).
However, the most shocking to me was that the 'distortion separation' was abt 0!? What I mean is that the distortion components on the silent channel were about the same level as the distortion components on the driven channel, even if the fundamental was 40-60dB lower. This was almost the same on both of these amps.

I suspect it has to do with the common PS, and possibly that the front end is on the same rails as the output stage?

Could somebody explain this further?

Hello there! I am a happy owner of a set of Magneplanar Tympani 1D speakers. I have rewired all 4 of the bass panels and have been pleased with how they sound. However, I have a large problem, one of the tweeters in them was destroyed (and I mean destroyed) at some point in their life to the point where the magnets and frame were damaged. It was a goner, and apparently Magneplanar no longer makes the tweeters anymore and so you can probably guess how I feel about that situation...

Anyway.

I have read a large amount of threads on this section discussing DIY ribbon tweeters. I am new to this website so please excuse my ignorance, but if anyone here has any guidance or threads discussing long ribbons, please link me to them as I need to read as much as I can before getting into this.

Efficiency is not a big deal here as from what I can tell that is the subject of concern for most. The bass panels are 84db 1 watt according to the Tympani 1D manual. What kind of magnet setup would I need to achieve that level of efficiency? I am aware that it is dependent on the size of the ribbon itself but any ballpark figures would be appreciative.

I am also thinking of doing a large scale tweeter, say 3" in width. I am looking for any opinions on whether or not a 3" wide ribbon tweeter would be able to go from 200hz to 20khz. I know the original tweeters crossed at 1.2khz but I'd like to take that down to delegate the bass panels to strictly bass, or close to that anyway.

I have a bit of experience and I'm good with rewiring a toroidal or traditional transformer for my needs, so for me that's not much of a concern.

Any links, information, or ideas would be excellent to be presented here. Question, has anyone ever tried using NiChrome foil for a ribbon diaphragm? I appreciate any replies, I really want to get these excellent speakers going. Thank you.

I'm reading the BOM for the diyAudio power supply board. It lists resistor values in a range, such as 0.47R - 1R or 4.7K - 22K. What determines which values I should use in a given build?

Dear fellow enthousiasts,

Via this post I would like to introduce myself 🙂 Music and audio has kept my interest all my life and in the course of time I build a small number of systems by my own design.

As a hobby musician, I played the bass in a number of local bands and it was great fun back then. Audio and making music myself were two sides of the same coin to me. As I became familiar with the sound of (amplified) instruments and drums and saxophones and trumpets and keyboards, I wanted to be able to recreate that experience at home. In the nineties, I watched, listened to and enjoyed great (and sometimes not so great) horn stacks in pop venues and discotheques. So I started to experiment with diy horn speakers, because I wanted that dynamic, crisp and focused sound at home too.

Because internet did not exist back then, I went to the library to study the sparse books available about audio design, I bought diy magazines and read about the many aspects that influence audio reproduction.

From my unavoidably limited knowledge, I started to build a horn system that has been modified over time, when new knowledge (and especially more purchasing power) became available. So over the course of some 25 years, I ended up with the system that is depicted in the photograph. I guess it will never be finished, but at the present state, I am very satisfied with the sound. My (mid)bass horns have never been replaced and in use for more than 25 years. Lucky shot I guess...

I would like to thank all contributors on this website, I have learned a lot! Some day I hope I will be able to start a small business (yet another one 😀) doing (horn)loudspeakers and tube amps for the local market.

I may contribute once in a while on a topic, but my academic knowledge of the matter is not that great. I hope I will be able to share some of my insights that I have picked up along the way, and post some pictures of my gear " to show off 😉".

Hi Members.
Would any Members be able to help me with the circuit diagram for the input selector board part number 2090-1. I do have the Quad 44 service manual and no mention of the board that I have in my 44. I have the late grey 44. I will be very grateful for any help given.
Best Regards Western 91

I have tried to source 1” horn or waveguide but haven’t found none in production or sale. Also European source preffered.

Looking for B-52 PHRN-1014, QSC PL-000446-GP or similar 90° x 60° waveguide.

Best compromise that I have found is 18Sound XT1086 but prefer lower crossover point than ~1,5kHz so larger waveguide like QSC would be better.

Any ideas or solution to this?

I tested this. (IQ audio Dac Pro) It has a clear, clean sound.

Unfortunately The treble (ie >2kHz) is piercing and sharp, and it makes me think this DAC does not have a flat response.

I much prefer the sound-card of the old laptop.


With the Same Amp and speaker setup:


When comparing to my laptop sound card (no effects or equalisation enabled)
with the IQAudio DAC pro+ on a Rapbserry pi 3..

The difference was obvious,
The High tones were piercing, female vocals and cymbals were unpleasant and sharp. Things only sounded normal after dialing down the treble on the amp. What detail am I missing out on now.. ?, by cutting down a chunk of sound with the dial.

With the old laptop setup, the Amp equalisation settings can be at dead-centre, and the sound is 'balanced' and full.


I thought I would share my encounter, has anyone else found similar ?

Hi Everyone,

Someone has asked me to recap this vintage Ampex 600 tape machine preamp.

Before turning it on I was trying to trace out the internals and relate the insides to the schematic and noticed some weird extra stuff in one corner! The signal in off the mic seems to be hook directly to the high DC voltage rail! When I tested pin 2 of the XLR socket it read 319VDC!!!

Here is the vid I made which shows the additional components ...

Ampex preamp safety issue - YouTube
They don't seem to make any sense at all!

The original schematic is attached.

Does anyone have any idea why these extra components were added? What they were trying to do? It's strange because none of it looks like newly added stuff (the extra caps and resistors look as old as the rest of it).

Cheers

Tom, UK

The relay on the input PCB on and off for a period. Speed is from fast to slow and then stop. Any suggestion to fix this problem?

Looking at power caps I see that I could pay more for higher ripple current values. I know it’s an important spec, but what’s a good value and what’s unnecessary?

In the interests of researching newer formats I have ... how can I say this delicately ... "acquired" a number of FLAC files. I can burn these to a CD using standard burning software and they play fine in my Oppo UDP-203 player.

The problem comes about when the files exceed the size of a standard CD. I have tried burning the FLAC files as audio files to a DVD but my burning software (BurnAware) won't allow that, telling me to insert a CD. D'oh! I can also save them to a DVD as data files and use the TV as a menu to play them, but the playback is mighty weird. Specifically, the two channels are out of time with each other, which gives an odd pulsating/echo effect and is very unpleasant. So, I made a few drink coasters so far. 🙂

I'm guessing that FLAC files store the data in chunks rather than interleaving them, but whatever it does this only seems to be an issue with the files large enough to need a DVD. i.e. 24/96 and 24/192 formats. I have tried to convert them to WAV format but have been unsuccessful so far, and in fact I'm unsure if WAV even supports such high resolution.

1. Any suggestions for a PC user (not Mac, not Linux) gratefully accepted. Preferrably not commercial software since this is of idle interest only.
2. It would also be nice to know what I'm supposed to do with DFF files, which also seem to be available. I've never heard of that format.

Edit: I forgot to mention that the files play fine using VLC media player, so they're not faulty. I also tried using a USB stick in the UDP-203 and got the same problem so it's not specific to the disc itself. The UDP-203 is supposed to be able to play FLAC files but it maybe it has issues with high-res formats. Insufficient buffering?

Class A Component Sunvalley EQ1616D
Recommended Components Fall 2021 Edition Phono Preamplifiers | Stereophile.com

Gramophone Dreams #42: Sunvalley Audio SV-EQ1616D phono equalizer | Stereophile.com


Class B Component ELEKIT TU-8600S

Recommended Components Fall 2021 Edition Two-Channel Power Amplifiers | Stereophile.com

Gramophone Dreams #48: The Venus Tube, Western Electric's 300B | Stereophile.com

Gramophone Dreams #27: EleKit TU-8600R amplifier kit | Stereophile.com

I want to build a mosfet amplifier (maybe the ESP P101) utilizing the transformer and heatsink assembly from a retired Tandberg 3012 integrated amp. The Tandberg was rated at 100W rms at 8 ohms / Ch.
The transformer secondary supplies about 57VDC +/- after smoothing to the rails. The original heatsink was quite robust with one pair of complementary mosfet outputs per channel. The original outputs were 2sj55 and 2sk175 rated at (ID) 8A and 125W ea. Tandberg seemed to think that these ratings were adequate for the 57V rails and functioned till the end without failure. Rod Elliot (ESP) seems to take a much more conservative approach with these higher rails (57V) and strongly suggests doubling up on the complementary pairs. As you can see in the pic the Tandberg heatsink assy. provides only for 2 TO-3 outputs per channel.
ESP P101 amplifier.
Rod recommends the Exicon ECX10N20 and ECX10P20 for the low power output. For my application (at the higher rail) I am considering the Exicon double die TO-3 versions, ECF20N20 and ECF20P20. I have read the pros and cons about the double die versions and still wonder if there are valid points to not using them. If it’s on the internet, it must be valid!?
Can I basically use the double die versions to replace the dual complementary lateral outputs without any real change to the P101 driver circuit at +/- 57VDC.
I emailed Rod and did not get a response.
OR… should I take the chance and use the lower power rated Exicons and justify it by what Tandberg used for power rated outputs. Seems to me that if this amp is used well below its rated output (like in my apartment), I should be able to get away with using the lower rated lateral outputs.

Looking at the table of First Watt amplifiers I see that single-ended designs almost always produce less power into 4 ohm compared to 8 ohm, while push-pull designs produce more. Is this inherit to the topology? If so, what is it that causes this behavior?

Hey guys, one of my next projects will be a new buffer line stage. The preamp I built a while back using 12AU7s sounds good enough, and for some things it is ideal. But it has too much gain. I am finding that many modern sources (like my DAC or an audio interface) have an output more than sufficient (by a fair bit) to drive an amplifier. With my current preamp (and it is by no means a high-gain design), I have the volume set at about 10% to achieve a normal listening level.

While it would seem that having a simple pot-in-a-box (passive) line stage would be the best, I do have some amplifiers (some of my big solid state amps, for example) have a pretty low input impedance, and while a tube line stage will add distortion, I find that even a low distortion design like my current preamp can take the slightly harsh edge off digital sources (all subjective and subtle). Beyond that, a passive preamp is rather dull and unexciting.

While I will use whatever transformers I have on hand, I think it would be good to design this to be cost effective using off-the-shelf parts in order to make it more beginner friendly. When I was looking for my first project (about nine months ago... I'm not a "seasoned veteran" by any means), I was continually frustrated by the number of designs using rare or difficult to obtain parts.

Enough rambling. I am thinking of doing a very simple cathode follower with a regulated power supply and possibly a constant current source. I've modeled some simple cathode followers in LTspice (just learning how to use it... whole new world of opportunities), and the 6DJ8, 12BH7, 6SN7 and 12AY7 seemed to perform fairly well. I have not modeled these with a CCS. The 12AU7 did not seem to perform quite as well.

As a side note, I think I have a pair of Jensen JT-11-FLCF transformers to use for a balanced output. These would be easy to omit, however, if someone wanted to save the $80 a pair of these would cost, especially if they didn't regularly use it with balanced-input power amplifiers.

My thinking, based off of inexpensive and obtainable transformers let's look at a B+ of around 260-300 volts.

So here's my real question for you all. What tubes do you all like for a cathode follower?

Ideas and suggestions are appreciated.

Thanks and sorry for the long post,

H713

It's a genuine query as I've got my set-up now and I've been told that when Bi-amping / Tri-Amping you get a synergy that gives apparent power that seems as if you have a much more powerful single amplifier.
Back story there; as way back when I was drooling over the monster Rotel RB 1090 and the sales person was telling me to Bi-Amp and use two much smaller Rotel RB 1070's which would actually have more "Music Power" and said sales man was saying double the actual music power of the 1090 and at a much more affordable price

So my current Tr-amp set-up is 380W into 4R + 150w into 8R plus 150w into 8R
Which is a bit crazy as I'll probably normally use about 15 to 30 watts when listening at a reasonable level
I suppose 680 watts per channel RMS is a tiny bit of overkill but if comparing it to a single amplifier do I really have the equal of a thousand watts per channel??

For those interested
Cambridge Audio Azure [ rebuilt]
Behringer DCX
Jaycar Playmaster / BASS
Rotel RB1070 / Mid-bass
Kenwood L-07M / Mid/tweeter

Into
BASS
Cerwin Vega Vega124
Midbass
Vifa P26
Midrange / Tweeter
Vifa P13 / Vifa D-27
Midrange/Tweeter

Hi everyone, I have a pair of Adam A7 active studio monitors that are about 12 years-old (and an Adam Sub8, which is a little newer) that I intend to keep.

About five years ago, the power transformer in one of them blew, and I replaced it with a transformer from Adam. In the past few months, the transformer in the other monitor blew and I replaced with a new full amp board from Adam (no individual transformers left).

I believe they are running low on replacement parts for these monitors, and I'm debating whether I should buy another amp board (for about £125) in case I have another problem.

Basically, the question is do you tend to find that there are just bad batches or transformers, or is it reasonable for them to blow every 5-10 years?

One other thing worth mentioning--the volume has recently starting fading in and out a little on the monitor that I fixed five years ago. However, I fortunately have a spare amp board now that presumably works fine except for the blown transformer.

Thanks.

KEF B139 SP1212 in good, working condition: $50.
(Also have another one with open VC and dented cone which can be included for free with purchase of the good one if you want it.)

KEF SP2055A 3-way crossovers, complete: $50/pair.

Prefer local sale in Los Angeles.

I picked up a couple Type 42 tubes from a lot this weekend. They look so classic that I want to build a single ended very vintage hi-fi (yes, I some may think this is a mis-use of the word) amp around them. I know I won't get much power and there's lots of talk about distortion, but I think I could work around it and be happy with the results.

Because part of the attraction is the "look" I want to stay with a 2 digit 6 pin driver. What is everyone's thoughts for a driver. To my uninformed search, it seems a type 76 is what I should target.

Thoughts?

If anyone has a schematic that would be nice also.

Thanks in advance.

I'd like to build a power booster for a low watt tube guitar amplifier that I recently built. The guitar amp produces about .5 watt sine and maybe 1 watt max. Great for practicing at home.

I saw a design for a power booster using tubes but only achieves a power gain of about 6. I'd like something more in the range of 60 - 100 to get me to 30 - 60 watts for playing out. Using some less common tubes it could be achievable but I like to stick to stuff that readily available.

Ideally, the booster doesn't change the dynamic interaction between the speaker and the tube amp's output section.

Mosfets are maybe a better choice for the application? This is an area I where I'm seriously lacking experience.

Would a common grid setup like this have a chance of working?

So I've finally accepted that I no longer have the time/drive for audio so I'm selling my stack. Crown XLS2000, Echo Audiofire12, Fuhrman PS-8RII power conditioner/delay powerup, 4 channel DIY Hypex UcD-180hg, and 2 channel diy Class D Audio SDS-470.

Hypex 4 channel: ucd-180hg x4 modules with gain resistor removed (great for high eff!) and Hypex SMPS. XLR in for each channel and speaker out is 2x 4pole Speakon. Powercon in/out for power and a power switch on front panel. Setup for rack mount only no feet but I think I drilled the enclosure for feet. Last used in 2018. Powers up.

Class D SDS-470: 2 channel module with Class D torroidal power supply. XLR in for each channel. Has stereo gain pot as well as separate trim pots for each channel. 2 pole Speakon speaker out. Powercon in/out with power switch on front. Also setup for rack mount only same deal with the feet. Last used in 2018. Powers up.

Audiofire12, XLS2000, and Furhman were from same system. Last used in 2018. All power up.

Will include diy TRS to XLR for all channels, diy Powercon cables, and a pile of 8 pole cable, 8/4/2 poles Speakons, and maybe more.

$600 takes the lot and I prefer pickup in Rochester, MN but may travel a short distance to meet. WILL NOT SHIP. I cleaned these up as best I could but there is some dust, scuffing, etc. Used in my home.

Hi, I have a Mark Levinson 35 DAC with HDCD my question is whether it can be upgraded? Could be some new components would provide better sound than the old ones?

Hello Guys,

Please help me trace or eliminate the ringing signal from the high side output side of the T2000 and T2001. I believe this is the root cause of ringing on positve side of output fets but please correct me if I am wrong. This is the first time I trouble shoot this kind of amp.

44H11 and 45H11 readings are good I also re soldered it. I also pulled out driver transistors and all tested fine no leak.


Attached are the signal forms.

I have decided to add a small full range driver to my quarter wave tapered line speakers which will replace the original tweeter and the xover will be lowered to 500Hz.

This involves adding a pipe from the front baffle to the rear panel to act as the mid tweeters enclosure. It needs progressive stuffing of course but the line is not very long (197 mm / 8") and that doesn't give much opportunity to soak up all the backwave.

I have no problem drilling the back panel of the speaker - nobody looks behind do they 🙂 So I thought why not extend the line. I could cut a 68mm hole in the back panel and install a black pvc curved 90 degree bend used on guttering systems. The pipe could be extended down the back of the floorstanding speaker to near floor level - that would give me a line just over 90cm / 3ft long.

This is just to soak up back wave of a mid tweeter so I presume it doesn't need tuning to Fs and no output at the end of the line is desirable.

Does that sound like a good plan ?
Does the line have to be tapered ?
Is it best in this case to leave the end of the line open ?

Many thanks .

This is a simple "yes" or "no" question, I guess.

Is the output of a standard variable-state filter 180% phase shifted in relation to the source? I've read that many phase shifts happen within the filter's integrators, but I don't know if the overall output is shifted as well.

I need to know this for a practical application and unfortunately my understanding is not enough to decipher it alone.

In the image you can find the exact circuitry I'm referring to.

Thanks!
Domingo

Does anyone know what these are on tannoy super tweeters st100
They are not giving a reading on a multi reader are they some kind of resistors any help would be really appreciate

Hello!
Currently I operate the 6H30 (half the tube) in 100v @30mA. However, my friend told me 80v @40mA is the best for this tube.

Any comments?

Thanks!

Hi,

I am trying to set the bias on two musical fidelity xas100 power amps (4 mono amps).

Chips used are SAP15.

Datasheet has an explanation, as do sites/forums online but I'm struggling to interpret the information and apply it to the amp. I'd say my knowledge is begginer.

Data sheet:

"1. Recommended Operating Conditions
➀Add a variable resistor (VR) between diode terminals to adjust the idling current. The
resistor having 0 to 200Ω is to be used.
➁Adjust the forward current flowing over the diodes at 2.5mA.
➂Adjust the idling current at 40mA with the external variable resistor.
Both the temperature coefficients for the transistor and the diodes are matched"

200 Ohm VR fitted between (D-D)
Assuming the 2.5mA will be set by design (across D -D)
All I need to do is adjust the idling current to 40mA Question is, where do I take readings from to determine the current?

Any advice/assistance is much appreciated.

Thanks,

Kevin

I've searched the forums and the 'net generally but can find no hobbyist input on the PP400 phono preamp. Well, I just gambled $20 on one and, to my surprise, it's not horrible. Noise is low, detail is OK, and output is not as overly hot as I'd been led to believe. Channel separation / imaging seems a bit mediocre, and it does seem that it's lacking some oomph in the low registers.

Has anyone done any modding or experimentation with one of these?

Hey guys I didn’t really know what to call this thread, but as I was sacrificing a tektronix plug in module for parts. I thought I should share a few photos.

Hello all , I have some questions about this driver from Lii Audio in China :





I am considering building this enclosure posted on their website :



I only have this 6.5W single ended tube amp :



Is this tube amp sufficient to drive these speakers ?
( I don`t play very loud )

Could someone more knowledgable on speaker design give their opinion on this design , or alternatively , know of a similar enclosure plan suitable for this driver ?

( I don`t have room to correctly place any open baffle speakers ), so I`m only really interested in a large bass reflex cabinet.


Would I need a sub ?

Thank you .

Hello all.
I have today received and soldered together one of those super cheap Chinese 'JLH' headphone amps, his 1969 design, so published the same year as his famous "simple 10 watt class A" amp.
Long ago I built the superb kit from Hart Electronic Kits in the UK, of his Chiara Headphone amp with its separate PSU.

This one, unlike the Chiara is all discrete and quite new to me.
I wondered as I was putting it together if it would be helpful to stop and share a scan of the board as a guide to some of the smaller components. These kits come with no instructions at all!
From other photos I have seen, the PCB has jumpers on the top surface where I have filled in the Plated-through holes. I think this is all that is required (?), and maybe not even this as they are PTH .
I hope (I'm out of practice) that I've put the diodes and the LED in the right way! (I did check).

3+ way speakers with only two AMPs & active line-level + passive crossover network

Hi... first post... I had an idea, wondered if it's a good idea and/or has already been done. Wanted to change the thread title to "3+ way speakers with active crossovers with only two AMPs & a line-level + passive crossover network" but too late. Respect to the technical proficiency of many on this forum — this idea's fairly simple.

I was playing around with the kx driver for Creative Audigy 2 ZS 7.1 channel sound cards and found it was easy (for a noob like me) to manipulate crossovers and band-pass filters and virtual cables to create multiple customised analogue outputs. I understand passive crossovers can cause phase distortion, so we'd rather use active line level crossovers connected to multiple amps.

If you had a 3 way speaker with frequency bands like woofer/mid/tweeter 50-200Hz/200-5000Hz/5000-20,000Hz (not sure how realistic those bands are) and programmed your sound card to output woofer + tweeter on one channel & fed it to an amp, and mid on another & fed it to a second amp, then put a cheap passive crossover system on the output from the woofer/tweeter amp with a cutoff around 2000Hz then the woofer and tweeter would get their signals cut off around 200Hz and 5000Hz by the software crossover and never experience distortion from the passive crossover cutting off inbetween them.

Or you might want a four-way speaker, which I've drawn roughly... one amp does woofer/tweeter, one does sub/mid... the thick lines indicate the line level output from the multi channel computer sound card with software crossovers, the thin lines indicate the behaviour of the passive crossovers between the amps and speaker cones (of course the source could be from any line level crossover, but it's a cost cutting plan & multichannel computer audio is cheap and a software crossovers are easy to tweak).

Hello.
Unfortunately, I have lots of stuff and I need to downsize because I really have no space for all my stuff not time to enjoy so many things built and bought during the last years.

FS my Jeff Bagby Helios Spaeakers.
Simply the best 2 way bookshelf I have ever heard.
SB Acoustics Berillyum Tweeter in waveguide + 9,5" satori bass driver + 10" SB acoustics passive radiator.
Crossover was built with intertechnik and Jantzen Audio air core coils (Cu 1,4mm) and jantzen z-std and cross cap

The best speaker Jeff ever made, and his last creation before passing.

I'm asking 1400€ for these fully built speakers, what I think it's like a bargain because only the drivers, not including crossover, wood and work, will be that amount.
they habe been used less than 15 hours.

Shipping within EU will be like 40€. I have all the original boxes for all drivers and would be safely shipped in separated boxes if needed.

I recently performed an experimental validation of the use of a floating VBE multiplier to perform local linearization of an output stage. The idea is to regulate the voltage between the VAS and output to a constant value.

I researched this concept after an investigation of feedback versus "error correction" last year. OldDIY showed this strategy used in a Russian audio magazine. This implementation is an attempt to distill the benefits of Hawksford "error correction" documented by Jan Didden and LKA and others into a feedback concept with small parts count.

Attached is a schematic, generator baseline, output stage with feedback bypassed, and output stage with feedback. For the generator baseline, I set a scope to play a sine + DC offset into a DC coupled gain of 10 amplifier. This amplifier drove the output stage under test. The concept works nicely (tested with a bias of about ~20mA), resulting in about 10-15dB measured distortion reduction of the output stage with local feedback being reduced to the generator baseline. Results are shown for 5VPk or 10VPk-Pk into 8.2Ohms.

EDIT -> clarify difficult to read plots (better measurement is shown in post 4 with sound-card/global feedback)

Generator Harmonic 2 = -71dB
Generator Harmonic 3 = -72dB
Generator Harmonic 4 = -81dB

Output Stage (NO FB -> FB) Harmonic 2 = -59dB -> -71dB
Output Stage (NO FB -> FB) Harmonic 3 = -69dB -> -77dB
Output Stage (NO FB -> FB) Harmonic 4 = -70dB -> -80dB

EDIT

Some unexpected things came up with this development. I needed to set the Miller capacitor C1 higher than I thought to be stable. Initially I attempted a >1MHz bandwidth, but I settled on about a 400kHz bandwidth. I also needed to add R7 which helped the circuit find a good DC bias. The circuit feedback using R1 adds a bit more base current to drive this output stage from the VAS, but it is not terrible due to feedback making this fairly constant.

I added Q2 and R6 to increase linearization in simulation, and bypass C2 to control high frequency impedance. I also added zener diode D1 to clamp the output. I used high voltage transistors, but if I can establish the zener does not increase distortion, then lower voltage parts are potentially allowed. Unfortunately, I have reached the measurement limits of my current oscilloscope setup (Digilent Analog 2 + rat's nest) so I did not measure the distortion contributions of these circuit elements.

I did successfully incorporate this output stage into a broader amplifier circuit with 3rd order global feedback (this is the gain of 10 amplifier in front). The net result is stable. The whole amplifier circuit is easier to measure using a soundcard because it feeds back on the internal DC offset of the output stage. So I will do some modifications and measure with my RME UCX, but it may be hard to find the effects of Q2/R6/D1 in the presence of global feedback.

Hello everybody.

I own a "SabajA20a" amplifier. This amp has a "Mornsun LOF350-20B24V PSU" capable of 200W/350W peak (14.6A max) running a PCB with two Infineon MA12070 ICs with 24V. Unfortunately they built the device in a sandwich configuration. The case is very narrow. If I put my ear to it, I can hear the PSU "buzzing/summing" inside the case. Im sure there is some EMI. If I turn the volume up louder than ~80% I get "white noise" from my speakers. Im sure this is the same noise I am hearing when I put my ear to the case.

I want to replace this PSU with a better one that is to be installed in a second case which I will put next to the amp.

Plan:

• PSU-Case : HIFI 2000 GALAXY GX147 Aluminium Case 124x170x40mm 3mm Front Panel Black - Audiophonics
• Preferred new PSU : SMPS300(RE,RS) :SMPS300RS Module d'Alimentation a Decoupage 300W / 24V - Audiophonics
• or
• Meanwell RPS-400 : RPS-400-MEAN WELL Switching Power Supply Manufacturer

Questions arose so far and promise to keep on arising. I'm in hope to answer some of them with your help.

1. Is the default Mornsun LOF350-20B24V PSU" a "single rail" or "multi rail" PSU? And do I even need to bother?
2. Which one of the SMPS300 versions (RE, RS, RxE) would be best suitable to power my amp? F.e. the RS is "single rail" and has no GND on the output side, whereas the RE version has a GND at output. Both have GND at the input side (Schuko). Do I need a GND at output? (The Mornsun-PSU I believe has none).
3. Will a more powerful PSU give me more power/headroom with the two MA12070 chips? In theory their max output in Ampere is 8A per chip, so I could go 16A, but the Mornsun does only reach 14.6A.

• SMPS300RS
• SMPS300RE
• SMPS300RhE

Pictures of open amp:

I am not sure if this is the correct sub forum for this, but I am sure there are people here who could help on this.

So I picked up a piece of non-working gear from ebay to do more troubleshooting and learning how to fix more things.

The picture attached is from a B&K CS117 and the problem they listed is it kept popping fuses. So the trace that has all the bubbles in it is one of the main ground traces on this PCB.

Now my question is; if it was yours, and you wanted to keep the item, would you gently cut the top layer, check the trace itself and say it was in the shape as the top; remove and replace it?

If you replaced the trace, where would you locate that and also what would you use to then cover it.

Now I know I need to find out why this was caused, but I do not want to cover that here, just what your thoughts on a repair.

Thanks, James

Ive been contemplating a new set of studio monitor ls for a while now. Ive been eye balling the M-Audio M3-8 active monitors for a while now but in the spirit of DIY i jist cant bring myself to pull the trigger :O

So! My latest plan involves a 2 way horizontal configuration using Dayton's ES180-Ti woofer paired with a Dayton PT2C-8 planar tweeter.

Call me a fan boy but I have had great sucess with prior Dayton products, albeit my previous projects where always low budget.

Anyways, my design goal is a full range 2 way in a moderate sized enclosure with 40Hz extension. Ive been wanting to hear this planar for a while now, I am privy of its narrow vertical dispersion given my studio is fairly small and this will be a near field application.

I would be powering these actively with an ART SLA4 using a minidsp 2x4 for x-over.

My questions, is it more acceptable to use such an arrangement horizontally given the tweeter dispersion pattern?

How will this pairing fair in a monitor application assuming an crossover of 3khz?

Ive also been looking are options from Morel and Dynavox but im liking that the dayton has more xmax and needs slightly less space to dig as deep.

Just wanted to emphasize, full and accurate representation to 40Hz is paramount for me given the genres I am mixing/producing.

These will be for monitoring so i dont need earbleeding volume, i have a second "master channel" with plenty of power for chest crushing bass when I feel the need for such a thing.

Anyways, I apologize for being long winded. Hopefully someone can chime in with possible cons/trade off of my driver selection and preferred orientation.

-Josh

I have some Aa tubes that will be used as a driver in my new amp Aa drives 50 monoblocks.

Per the attached Aa spec sheet, typical operating values: 3mA, 220V, -2V

Would like your thoughts on the following 2 alternatives for Aa operating values:

Option A
Ua = 240
bias = -3
Ia = 3.4mA
225-115=110Vpp
(110V/2)/1.414 = 39Vrms
Dissipation = 0.0086a * 110V= 0.95W = 63% max
(max dissipation = 1.5W per spec sheet)

Option B
Ua = 220
bias = -2.4
Ia = 3mA
205-115=90Vpp
(105V/2)/1.414 = 32Vrms
Dissipation = 0.0085a * 90V= 0.76W = 50% max
(max dissipation = 1.5W per spec sheet)

Not sure if this is enough to swing / drive the Type 50 output tube.

Also, I have a 4Vac filament tap. The Aa spec sheet calls for 3.8V. Do you foresee any issues using 4V instead of 3.8? I will try AC as I like the sound of AC, but if hum becomes an issue, then I will go to a regulated 3.8Vdc.

Note: The attached Aa curves are courtesy Intact Audio, Dave Slagle.

Thanks

I have a pair of these drivers that have been in use in Nelson Pass's TL speaker box designed for the driver. It's quite nice. But the drivers both need refoaming. I've done this on several drivers in the past so not too worried about the job. But the original foam was applied to the back side of the cone. Just how important do you think it is to apply the replacement to the backside of the cone? I can't see that it would make any real difference, though there would be a lip of the foam where it joins the cone. Again, hard for me to believe that would matter a lot. I'd imagine getting the foam OFF of the back would be more important relative to mass.

Anyway, I'd be interested in any thoughts you all have. Thank you!

I got a big bag of 0B2 tubes of questionable provenance for about $0.80 each, and lucky me, only 2 were dead. Three of them are labled IEC Mullard, "MADE NI ENGLAND". They are unlike any 0B2 tubes that I had ever seen, though my experience is very limited. Instead of the usual cylindrical innards, there is a backwards "S" shaped plate(?). The regulated voltage is spot on at 108V, and they light up very brightly even with only 6mA running through them. I did a pretty extensive search on the web and didn't see anything like them. Anyone seen them before?

Hi

Just curious what would be better sounding amplifier to HK990 ?

So far i have modded HK980 and it sounded quite nice... would be willing to say it sounded more "musical" than the current HK990 with a bit of mods.
I tried to go to tube amps but with the kind of music i listen to ( genres all over the place ) it seems not to be fit for the job.

Power wise i have no reservations (running Fostex FE206En ) as a matter of fact i was looking at maybe building the "Le Monstre" with original 8W of claimed output.

Are there any other more "musical" amps than the HK990 in the DIY space ?
Is it even worth to DIY anything since the HK990 seems to play everything effortlessly ?

Thanks for the answers 🙂

Hi All,


I have a Mission Cyrus 2 amplifier (after fully recap and some other tweekings), it's mains transformer is 200VA (2x28Vac) rated and I was wondering what will be the effect of replacing it's transformer for a higher VA rating and output voltage, let's say 300VA (or higher VA rating) 2x30v output.
I've read that the PSX (optional) power supply's transformer rating is 500VA and the PSX DC voltage output is +/- 40Vdc.
I attached the schematics of the Cyrus 2 power supply section as a reference.


Thanks

Hi all, I have a dumb/basic question that seems to not have been asked. I'm attempting to maximize a space-constrained, hopefully-stealth build for car audio. Is it possible to mount the subwoofer magnet through/ outside the enclosure? It might save "just" 3/4", but it could be more in some cases. For example, the Tang Band W8-1363SB has an exceptionally long but thin magnet. (However, I believe this magnet has an open center which would make this stupid? confirmation appreciated). You could recover a lot more space with that, if the bump is in the right place. And it actually seems beneficial, at least structurally-speaking.

Yes, this might create more heat build-up/less cooling of the magnet. Well, you could use a tight-fitting aluminum ring with a bit of thermal glue to achieve a similar surface area for dissipation.

Anyway, I've seen very heavy magnets supported 1/3 to halfway around with ply in HT applications, to prevent destructive torsion on the face of the box. But I've never seen a magnet fully surrounded by wood or protruding from the enclosure. Any tips appreciated, thanks!

I was looking to build a simple 2-way speaker similar to the BR-1 kit on Parts Express, but instead of the 6.5" woofer, use the 10" DC250-8 in a sealed box. I am familiar with the 6.5" DC160-8 and while I think it is a quality woofer, I am looking for a bit more bottom end without porting (for better transient response).

Looking at the DC250-8's response graph, it seems a good crossover point would be around 2khz. However I know it would be advisable to keep the center of the drivers within a wavelength of each other (13560/2000 = 6.78") that would be physically impossible at that crossover point (Minimum ~7.5"). However, if I used a crossover of 1.5-1.8khz I would have enough spacing to make it work and I think these drivers could cross over in that range assuming I used a 2nd-3rd order.

My question is, are there other potential issues I am not seeing with this design? I may slant the baffle to account for time delay between drivers as well. I just have not seen many 2-way designs with a 10" woofer. I assume this is generally because the cross over doesn't work, but I think it would here.

Please advise me for other problems I may not be accounting for or for other suggestions all together.

Thanks

Hello Everyone,

I'm trying to rebuild the PSU of my old class AB amp.

The original PSU have just a 150va 25v secondary with 2 x 10,000uF; and I have on hand a 225va with 2 x 25v secondary, 2 x 10,000uF and 2 x 4,700uF; all capacitors are Vishay56 series 63v.

Space is not a constrain though new PSU has slightly bigger toroidal and 2 more capacitors.

I am wondering if I should put the 10,000uF closer to the rectifier and the 4,700uF on the amp side, or is it better the other way around?

On PSU 0v, the plan is to have a bus wire across a pair of capacitor, but I'm not sure if there is any difference to have the bus wire across the pair of capacitors closer to the rectifier vs bus wire across the pair closer to the amp. The speaker returns will be connected to this bus wire.

Thanks in advance for all your input and advice.

Searching for the right mix of cable(s) features for the dual mono power supply for the Pearl 2.

Found this Harwin Unveils New Twisted and Shielded Cabling Solutions for Gecko Products | Harwin

Thinking each board should/will have a stand alone shielded power umbilical cable with twisted conductors to minimize inductance.

Understanding that the cost will drive actual parts used "used for space" equals expensive assembly.

Thoughts? Good enough? How would you make it?

During capturing some VHS tapes the unbalanced red and white audio RCA stereo coming out the VCR and going into the BrightEye75 pro capture device which is equipped with balanced Phoenix style connector audio input (see photo), I've noticed that some tapes have very low level even with the gain cranked all the way up in the BrightEye75 audio menu I still have the level below -10db in the capture app.



The hookup instructions for the BE75 recommends connecting the cold and ground to the ground side of the unbalanced and the hot to the positive side of the unbalanced side, this still produced low level, what is the easiest way to boost the level by 6db without an external box that requires too many cables.

Will these gizmos work without sacrificing the quality? and how to power them up?

TEAS - Test Equipment Acquisition Syndrome - YouTube

I did a kick watching this video!

Art

I think this might be my first post here, I am certianly a noob to the forum and today is likely the longest I have even been logged in.

Lived in So Cal for 47 years and a few years ago moved to West Tennessee.

I have been fairly consistent in activity level, building and designing tube amps for audio reproduction since about 1994. For many years I bought and sold vacuum tubes (and tube relateds) in So Cal and supplemented my income with such. Then it became antique radio repair, then HAM radio, along the way I started a firm that provided low voltage and communications services for LA/OC and all of So Cal. My base was mostly in West LA. Along the way I got to experience systems like Cello Music/Levinson, countless ridiculous audio and media systems working for the LA Elites and that experience helped guide my tastes, preferences and expectations from audio and other electronic systems. Ive been In the homes or Perenchio, Murdoch, Senators, actors/actresses, producers and directors (Copollas home to name one), Paramount, Warner Bros, CBS, NBC (every studio in So Cal), musicians, comedians, philanthropists, bankers, felons (rich ones), engineers and retired Secret Service agents, plus Vic Edelbrock, Parnelli Jones, Vasek Polak and the President of Nissan Motors at his CA rental home on Portugeuse Bend Road (just to go a different direction in the list), etc. My work allowed me to meet an inumerable host of people and most all of them had audio and video systems (why I was in their homes and businesses to start with). I remember a guy name M.C. Hong in Rolling Hills, CA (Evergreen Shipping, China seems to ring a bell), All I know was he had $7000 a sheet wall paper (it was gold leaf) being hung for the second time in his home, as he didnt like the test wall (like 11 sheets required) and had the prior equally expensive paper removed! So I met a diverse group of people, I was fortunate and it was a career. I have heard many audio systems but in the last decade that has been on a serious decline, really serious decline. And now I hear NONE.

A case in point, it was a video system in Encino that put me in this Chinese guys house, really great fellow. He was a strip mall owner and lived on a short street off Van Nuys Blvd West of the 405 by a few miles. He had audio systems in every room (BIG BI-LEVEL house) and had maybe 6-7 of them in the great room downstairs. Enough gear where you wadded through it! He traded on an open account with some well knonw audio store even further west on the Blvd. It was a marble crypt, hard surfaces everywhere. But this is where I first experienced electrostats as tall as me at 6 foot, maybe taller. Big 120 Watt Jadis monoblocks feeding them (with rows of Genuine Tungsol 6550US STs on fire). Opera is what I heard and I had a fit listening while I worked. Never heard music so good and instead of enjoying Jim Morrison, I found myself really immersed in Opera for teh first time and enjoyed crap out of it. I broke my foot at that job, dropped a heavy item in his driveway and broke metatarsals while I honored his request to go shoeless in the house. Magnepans, tubes---- Thiel speakers, horns, just stupid amounts of gear. That is when I said- screw Mosfets and Silicon!
Just a fun memory to give some insight to my history and experiences.

When I moved to TN I did not retire. I became a supporter of agriculture, I work for farmers and agriculture businesses and also manufacturing plants of all sorts. I no longer build audio and video systems, I can't even find one here....... I know where the RICE, yellow soy, corn, milo, hard red and soft white wheats are grown and I can probably grade a grain and get pretty close to a price for a given moisture and Bushel Weight. Meaning........ the electronics I see now are PLC's and motor controls, and scales and moisture meters and process switches and tractors and grain bins with blowers and heaters! You eat and have diesel and ethanol and rice in part, because of my participation in agriculture. Im proud to be part of it now.

I wanted to post to say hello and maybe reach a sourcepool of WEST TN, EAST AR, NORTH MS goofs that are looking for another goof that builds audio gear or at least likes to listen to "quality music" whom I can communicate with. I have ZERO except the Atlanta Audio Society (IIRC) and they have never replied to any email I have sent. Plus they are too far to bother. I am shocked that there is NO Audio Club of any kind here in and around Memphis..... the home of SUN Studios, Beale Street, blah blah blah. I dont even think there is one in Nashville. I have searched, I find nothing, anywhere within reach.

BTW: Im NOT OPPOSED TO HELPING FOUND OR OTHERWISE INITIATING ONE! Hint Hint!!

Anyway, thanks for a great forum. I have perused it MANY MANY times for anecdotal data (for many many years) and it has been a useful resource. If anyone has any experience with Burning Amp Fest and how that whole "bring your gear for audition" works, Id sure like to hear about it. PM me.

Not sure I have anything to contribute unless you want to know what moisture you should sell your yellow soy at for best return and even then....... At some point Ill probably speak up about some designs and some theory (mine not yours!) but I spend less time crunching numbers for a perfect load line and I like what Nobu K. Shishido always leaned toward ..... using his ears more than his eyes because we cant listen with our eyes and a load line sounds horrible. That whole Eastern Medicine vs Western, not that a rat tail tea will or wont cure me of a disease but there is more than meets the eye in audio, there is always what meets your ears too. My wife cant hear a load line and she could care less where the Q point is, so really I shouldnt necessarily focus on one. If it sounds awesome, then maybe its right???? If she likes it and proclaims it awesome, even better?? Quite honestly Im sick, the build and design time is far more appealing than the finished product...... Im sure in a group of DIY'ers I am alone in this sickness to which there is no known cure.

I am corerftech absolutely everywhere and there is no other. If you see that handle somewhere on the net, its me!

Mike in Germantown!!
Formerly of Garden Grove, CA for 47 years.

Bare copper? Tinned copper? OFC? Something exotic? Just curious what’s popular.

Here is a little project I have been working on over the past few weeks. Its a "clone" of the WLM Stella bookshelf speaker.

It uses the Visaton drivers W130S 5" mid-woofer and TW70 paper cone tweeter.

The tweeter has a fast rolloff below 1.4khz and 4th order acoustic slope can be achieved with just a capacitor. The W130S sounds very smooth and has good bass response for such a small woofer.

Some measurements to come shortly.

Hi there People,

does anyone out there remember the manufacturer or model number of a passive box which was to be introduced between the CD analogue output and the CD input of the amplifier. This was in the early days of CD (mid 80s ?) and it was "supposed" to make CD sound less digital. As far as I remember this box was designed to emulate some of the physical characteristics (failings?) of a cartridge, I think crosstalk was mentioned as the main idea behind it. I also seem to remember it was a sealed unit so the last statement could be pure conjecture.

I never heard it; I am just trying to remember what it was

thanks in advance
Neddy

Hey guys, I'm curious as to how infinite baffle subwoofer ensloures might perform against paraflex, generally speaking.

I'm working with the following 21" driver, for pro audio application. Also if there's any good guides for modelling these kinds of enclosures using Hornresp or any other software, would love to know it.

Much thanks!

Hello,

I have a problem that just started happening with this amp. When it turns on one of the channels sends a DC signal and tries to jump my speaker cone out of the magnet. It sometimes does it a few more times within 30 seconds but then stops and operates normally.

If I shut it down then turn back on within a minute it doesn't do this. If I wait a little longer it sends the DC again. It is only happening in the one channel.

Any ideas why or how to troubleshoot? I searched for a schematic but wasn't able to find one.

Thanks for any help...

Well I just had to share about something I just discovered. I recently picked up a DIA-150 integrated amplifier off Kijiji for $100 bucks because it wouldn't power up. I thought it was a great deal and maybe I could fix it. I tested the amp sections and they were fine. The problem seemed to be on the control board because it just wouldn't power up.

So I dissembled the entire amp, something you got to do to get at the the control PCB. And after some investigating and removing parts I found the culprit. Someone had removed the filter cap for this board and carefully cut through the copper trace leading to the voltage regulator that powers up the on/off and input selector circuit. Then they resoldered the capacitor back into place so no one could see their handy work.

Man, that is greasy. Someone either really didn't like this guy or it was a ploy to buy the amp for really cheap claiming it couldn't be repaired.

It also looks like the volume pot has been sprayed with some kinda oil.

Another episode in the massive process of semi manufacturing concentration, after AD purchasing Linear Technology, it is now time for Maxim to be digested by one of the two giants (AD and TI). Short of the fabless companies relying on silicon foundries like TSMC to manufacture niche products, AD and TI is all what's left out of a once burgeoning and diverse semi manufacturing market in the US.

Never really liked Maxim, their strategy to rather quickly obsolete their products was annoying, plus that they did not have a wide range of high voltage linear products, but some of their power management products were useful in audio. They had a very generous samples policy, which likely will vanish in the usual corporate massacre that will follow the acquisition.

Hello! I have a sound system composed of 4 electrovoice eliminator speakers and 2 horn subwoofers. All are phased checking
Speakers go fullrange and subwoofers crossover the problem is that you have to press the reverse buttons on the crossover to sound the bass full. that is, they cancel each other out on normal 0 degrees. It is normal to use the reverse button ? the speakers are in the club at a distance of 3 meters between them
The speakers used in the subwoofers are b & c 101b.

If there is a document I've not found that covers it, please send me there instead. But, I have some basic questions to help me clarify my understanding of power supply design choices:

1. The transformer provides the power used by the system, which means the transformer needs to be rated at least as high as the maximum draw expected from the system. If you know a system will only ever draw a maximum of 300W, is there any benefit from using a transformer greater than 300VA?

2. I understand that the filter capacitors smooth out the DC voltage and provide voltage when the draw from the system is greater than the inflow of electricity through the transformer. How does the filter cap capacity relate to the circuit that will draw on it? IE, how do you know how many farads you need for a given circuit? And is there any benefit to adding more?

3. What are the benefits of dual-mono power supplies? I understand in principle that having a separate power circuit for each amplifier circuit has benefits, but I'm not clear on exactly what or why. Additionally, Nelson Pass describes a "dual mono" power supply with one transformer feeding two bridge rectifiers and two capacitor banks. To what extent does this achieve the benefits of dual-mono design, and what is the tradeoff of using one transformer vs. two?

Hi there,

I'm calculating a case size for the first time and I haven't quite understood a couple of things yet. I also included a photo.

I have a sphere with a diameter of 50cm. Corresponds to a total volume of 65L.

I would like to install a 12 inch woofer there.
Now I have found such a table on the Internet:

Woofer Size Enclosure Volume
4 ".25 - .39 cubic feet
6 ".35 - .54 cubic feet
8 ".54 - .96 cubic feet
10 ".96 - 1.8 cubic feet
12 "1.8 - 3.5 cubic feet
15 "3.5 - 8 cubic feet

According to my calculation, with a volume of 65L I come to 2.3 cubic feet. A 12 inch driver would fit.


Now we come to the second part in the photo. Because I somehow have to build the drivers into my sphere, I have to make sure that one part has a flat surface.
My 12 inch driver would now come in there.

Now I only have a remaining volume of 39L or 1.3 cubic feet. If I go according to the table, would a 50cm diameter case still be too small for a 12 inch driver, or am I getting that wrong?

I have a pair of Stax SR-X Mark 3 headphones.
I'm not having any luck finding replacement muffs.
Last pair were cheap generics that fell apart after a month.
Years ago I found one set on fleabay in Japan, but they were never sent and they never replied.

So, where can I get a decent set ?

Hi all,
Been out of the car audio scene for about 20 years so I need a little advice. Would like to get my daughter a sub + amp for her 2010 Subaru Outback. I would like to keep it as simple as possible. Something she could move or take out in case she needs the trunk space and so.ething that could be added to her existing stock stereo. I thought about something like a 10" Bazooka bass tube or something similar as it would be easy to move or remove. Like I said, been out of the game for a while so just looking for suggestions. Thanks.
Paul

Need help on designing a car subwoofer enclosure

Hey guys,

I hope I am posting in the right category. So I've been trying to design an enclosure in VituixCAD and WinISD. I've got some difficulties making it meet my desired specs. The cab + subwoofer are designed to be in a car trunk.

From what I understand it would be best fit into a rather small enclosure (max 40l), I've tried many things and past 45l f-3 keeps getting higher.

I just achieved something pretty good. My biggest problem is the cone excursion though.

The speaker I have is this one :

Sica 10 SR 2,5 CP 4Ω. Specs are attached.

I would like to get a solid 40Hz @ f-3. Here are the specs of my actual simulated enclosure :





Actually pretty good IMO. But then, as you can see, here is the problem : the cone excursion.



This @200W (which is the maximum power I can get from my amplifier)

i get roughly the same result in WinISD.

Is that a problem ? Is there another problem I don"t see ? Do you see a better alternative ? I'm a total beginner so I would be happy to get as much info as I can.

Thank you !

Hiya,
I have a cd80 i that bought new in 1993. it is a fantastic player, one i would not be keen on replacing. My cd80 runs pretty hot thouhg, the heatsink runs hot (as it always has) but the cds often come out of the drawer very warm after playback - is this normal? the machine behaves well in all other rspects. I am concerned as i have just placed damping sheets onto the inner chassis, case and ICs, and wondered if this was the cause.

One of the lights above above the cd drawer that create the blue glow (is this the same as the green/blue lights that others (Krell, YBA) bathe the laser in?) has failed - are these common devices?

Finally does anyone have a schematic or know where i could find one?

thanx

Hello,
I have a question regarding the throat flare rate, there are several topics on the drivers, but I do not find an answer on the choice of the output angle.
In the book "Acoustics" Leo Beranek, he talks about the best ratio between membrane surface and exit hole.
In EV notes, the mismatch between horn and driver, I tried to search the internet, but there is not much literature on the subject.
In practice, I use the R-H ssd5600 drivers with for now, the horn associated cbh 250-6.
These drivers have a half exit angle of 6.9 ° degree.
I simulated the horn with hornresp,
the curves provided by the software are similar with R-H datasheet.
I want to make a horn larger, but if I keep the angle of the first part of the horn (S2), more or less similar as the cbh 250-6, for this match, the exit throat, even with a horn that is 50 centimeters longer,
there's always that same fall, the low frequencies.

Apparently if I want a very flat curve, I have to reduce the half angle at about 2.2 ° degree.

The QUESTION is: what is a mistake to want to change the angle of the phasing plug, suitable for the horn,
What kinds of problems could sustain, resonance, yield loss.
Any of you would have done tests in this direction?

Best Regards
Stefano

Good afternoon folks


this I undersatdn will be a long shot, does anyone have access to or know where I can accquire/pay for a Wadia 15 (non i) service manual at all?


May thanks


Sighound

Does anyone know who makes the Tube Amp Doctor EL-34B STR?

Thank you

I have been using these speakers for some time, at one point four resistors decided to self destruct. I tried all the values that Ray Vandersteen recommended but did not like sound. I sent them off to a guy who "fixed" them for me but was still unhappy with the result, I am still unhappy as there is terrible sibilance and there is a lot of stuff I just cannot listen to it is that bad. I have tried altering resistor values but to no avail.I have also changed out the metal dome tweeter for a soft dome Audax TWO-25-AO but this has not cured the problem. Something in the circuit is interfering with the treble but I am at the end of the road, does anyone have any suggestions please?

I am looking to buy an assembled and tested Мiro's AD1862 DAC. I prefer from Europe.

Acoustic Energy 109. How to "guestimate" port tuning based on crossover point

I have all the drivers and crossover to make an Acoustic Energy AE 109.



What I do not have is the length and diameter of the port of the woofer (rear ported) and mid woofer (two front ports)

Crossover : 3-way, 8 element 12dB per octave slope at 300Hz and 3kHz with high power low-distortion toroid inductor for bass
Overall frequency response : 35Hz to 22kHz
Frequency Response : 55Hz to 18kHz [± 3db]

Based on the frequency response of 35 hz to 18khz and crossover at 300hz, can I safely assume that the port tuning of the woofer is around 45hz and 300 hz for the mid woofer ?

I do not need the design to be perfect, this would be used as a secondary system.

Can an opamp (TL071) in a subwoofer plate amp cause fuse and power transistors to blow?

FS: Mini Dissipante 3U-400, black, like new

sold!

Having my 3rd Output-stage in the works (beside just as many input-stages), wich all will end in a modushop-chassis, the chassis-construction is itching me a bit.

Especially the dissipante/mini dissipante seem a bit awkward to me.
Because: The construction is quite graceful and has very generous tolerances in every direction. The steel-frame that holds every side together allows the heat-sinks, front- and back-panels to be adjusted, which is nice at first glance, but makes the final assembly tricky.

Since in the end, every part has its very precise position, and the parts seem to be CNC-made thus allowing narrow tolerances/high precision... Why isn't this reflected in the steel-frame?

(And the greedy wannabe-designer in me also keeps nagging about the screws. Should be possible to have a build where there are barely a screw visible, and the front- / back panel maybe even could be plugged in and secured by just 1 screw? But THIS is just me.)

Hi,

I recently bought mono power amps from a very small French brand 'Cairn', being the Cairn MEA 500. Very nicely built amplifier, sounds sweet and powerfull, and the case is absolutely beautifull. 130W 8Ohm, 250W 4 Ohm.

It has a 500 VA torrodial.

The Cairn MEA 500 has from the factory 37600 µF of filtering capacitors.

There is a factory extra option to use an external box 'full of capacitors' which they call the 'CAPA'. It contains 16 4700µF capacitors, increasing the capacity to 97000µF. This would allow for 40 A currents and improve the amplifier.

The external box however is extremely ugly. I wonder what it really adds to the amplifier? for esthetic reasons I would just remove those boxes, but if it really has an added value I would keep them and possibly make a nicer looking box for them, or try to put them somewhere where they are less visible.

thanks!

hello, currently in my last year in EE bachelor program. did some computer science and much prefer working with analog signals but I am fairly more proficient with digital stuff even though I did more EE because well analog is harder.

anyway been getting started working on audio projects at home. amplifiers power supplies and even speakers. I have been accumulating components to prototype whatever thing I find in a book so I keep a continuous learning path

I just ordered my first modern book of amplifier design and its Audio Power Amplifiers: Towards Inherently Linear Amplifiers by Mr Arto Kolinummi

its not as common as the Self and Cordell books but I saw it get some recognition. I will probably get the Cordell book soon too but I dont think Ill be getting the small signal analysis book I learned quite enough about that in school and its confusing to say the least. just a lot of theory

I have some older books from online that are out of print and some older design books I bought. its very useful in my opinion to see the different design ideologies as nobody is going to explain everything so you might get a bit of information from every author.

did some simple stuff in my design lab course like a really simple LM386 amp circuit with a jfet op-amp pre-amp for a microphone but thats about it. I would like to believe im not an idiot that doesnt know how things fundamentally work but obviously real world results are very different. gonna be a lot of trial and error and experience


any less known book recommendations?. any tips. either way I probably wont be here too frequently because I usually look up information or exist on reddit about this. but might ask a few questions.

Hi
I'm planning to do a hack on my MiniDSP DDRC-24 to get SPDIF output. I will follow this guide: MiniDSP DDRC-24: MiniDSP DDRC-24: Modified To Output SPDIF - Album on Imgur in which the I2S data is taken from the input of the DAC chip on the DDRC-24 and send to a I2S to SPDIF converter. In the guide one I2S to SPDIF converter is used to provide SPDIF for channels 1 and 2. I would like to add another converter to also get SPDIF out for channels 3 and 4.

My question is: Is some sort of buffer needed to buffer the I2S signals when using 2 boards? And how would one go about doing that?

Hello,

Trying to see how many people here would be interested in a group buy of my Starkrimson Ultra Amp modules.

$892 per pair -- 15% discount -- minimum 10 pairs of modules sold
$840 per pair -- 20% discount -- minimum 15 pairs of modules sold
$787 per pair -- 25% discount -- minimum 25 pairs of modules sold

Features:

• Fully balanced from input to output (w/ differential input)
• Differential and single-ended audio inputs
• Extremely low noise and distortion
• Power output into 16Ω/8Ω/4Ω: 125W/250W/500W
• 2-ohm capable
• Overcurrent, overvoltage, and thermal protection
• 20A output current

Specifications:

• Gain (balanced input): 19.05dB
• Gain (single-ended input): 25.05dB
• Signal-to-Noise Ratio (SNR): 120dB (A-weighted)
• Input Impedance balanced/single-ended: 44k/22k
• Sensitivity (balanced input): 5Vin for 250W into 8Ω
• Sensitivity (single-ended input): 2.5Vin for 250W into 8Ω
• Damping Factor: >700 @ 1kHz
• Size: 4.95" (125.7mm) x 3.75" (95.3mm) x 1.45" (36.8mm)
• 6 x M3 / 4-40 mounting holes
• Required Power Supplies for Module (Hypex SMPS1200A100 provides all required voltages)
  • +/-36V (+/-30 to 42.5V) - Amplifier Power Rails
  • +15V (11 to 16V) - Mosfet Driver Supply - Referenced to -36V rail - 100mA minimum
  • +/-12V (+/-10 to 22V) - Analog Supplies - 100mA per supply minimum

Full test results here:
Starkrimson(R) Ultra Amplifier Modules -- 250/500W into 8/4ohm | Audio Science Review (ASR) Forum