SOLD
For sale is a pair of C3G pentode tubes, with outer metal shield removed to reveal their beauty 😍

They have been used lightly for experimenting. And these are rated 10k hours tubes. Plenty of life to go.

75USD shipped registered with tracking. Would be very well packed. PayPal FF only please.

Hi Peeps:
I have a Signature MPA 3250 Monster AMP ( 3 channel ) I'm curious to know if anyone knows of a source for a "Service Manual" not the owners manual, I have that 😕 . I have an issue with it kicking out when it's cold and suspect the relays or the overpwr trip circuit. It kicks out even when not playing with zero volts in even.
Anyway I'd be happy just to get a schematic.
I contacted Monster and they refered me to a repair center down South. I live in CT. and the AMP weighs in at 92 lbs. Yeah I'm going to ship it to them and back... Thanks for reading.

John Mik

This thread caused me to look at Unisonic's product offerings and it appears that Unisonic will continue making the NE5534 in surface mount.

Unisonic UNE5534: https://en.unisonic.com.tw/uploadfiles/836/part_no_pdf/une5534.pdf

They also offer the UNE5532: https://en.unisonic.com.tw/uploadfiles/836/part_no_pdf/une5532.pdf

I'm currently multi-amping my LaScala clones, using a Dayton Audio DSP-408 active crossover. There is a lot to like about it in terms off functionality: 4 channel in, 8 out; 10 bands of parametric eq per out, up to 24db Linkwitz-Riley/Butterworth/Bessel filters and a 20hz-20kHz response. It had a decent UI, with bluetooth/iOS connectivity and a windoze interface, as well. However, I would like to improve the noise floor, is has a slightly perceptible hum that is present when music isn't playing. It's entirely single-ended, but I would prefer balanced, at least as an option. Finally and this is the biggest issue for me: the DAC is limited to 48Hz, 28-/56 Bit processing, which regardless of whether it's audible or not, effectively nullifies my Schiit Audio Bifrost 2's 192Hz, 24 bit capabilities for hi-res audio file playback.

What options are available to maintain the functionality aspects that I like about the Dayton Audio DSP 408 (ins, outs, 10 band PEQ, filters & frequency response, ui and relative affordability) with better processing, at least 96Hz/24 bit, but preferably 192Hz, 24 bit, balanced inputs and outputs? I know there are pro options from companies like Ashly that are more expensive than I'd prefer and more affordable pro options from dBX, Behringer and others skimp on PEQ, or ins/outs and/or have poor UI functionality... I'd prefer to keep in the $500 ballpark (I'm ok with used components) and this is a big ask, have either iOS or Mac OS UI.

can this be done?

Hi
We have 2 Mackie HD1521 with defect Woofer in one of them. Since sourcing parts for this model is hard, would it be suitable to replace the woofer with a woofer intended for the Mackie SRM 1550? The spec on the HD1521 is 700 watt RMS, 4 ohm and neodymium magnet, while the SRM1550 has 600 watt RMS, 4 ohm and ferrite magnet.
Or would it better to replace the woofer in both of the speakers with the SRM 1550 woofer?

Hi,

I have a pair of Mackie HD1531 woofers that are broken that I want to replace. Does anyone have a woofer to recommend or can someone recommend someone who can help find a good replacement for these woofers.
Is there something I should think about when switching? I have a total of 4 that I use at the same time and therefore I want as similar a sound as possible. The original woofer is not available.

Henrik

This is for a barely used VTV Purfi amp. It has the stock buffers/no trigger (Default) I bought it new earlier this year and only used it in my smoke/pet free area.

$20 shipping.
I do PayPal F&F or Zelle.

I'm Selling my Raal SR1A's which I drove with this so I don't need it anymore is the only reason I'm selling (I'm moving so less stuff is better at the moment)

A this price you're at about as low as you'll ever find it ... you can't even order them and put them together at this price. You could literally pull out the internal Purifi Modules and probably sell them for more or buy a completely separate case and still be below what you'd pay normally.

The power part sometimes may come a bit out if you pull out the cable but you just push it back in. All the VTV models do it. It doesn't bother me as you don't yank out the cable too often. There's a bunch of holes on the bottom (same with any Ghent-like case: they just drill lots of holes so they can use them for many different types of internal amps)

It ships in the original box it came to me in.

I want to make unbalanced line ICs.

For this application ChatGPT recommended Mogami W2534 quad-core. Strangely (me thought) AI told me to employ only the braided shield for ground return and only the centermost conductor for signal. Is there potential advantage in using the 3 remaining unused conductors and if yes, how?

Please comment and/or suggest otherwise. The proposed RCA unbalanced line IC connects preamp output about 40-ohm > sub amp input about 12k-ohm. About 25' on the R side, about 3.5' on the L side (2 sub amps)

TX! Surprised no thread referral!

Hello, i just recently bought a new lanzar htg237 amplifier, which i hope to connect to a "In-phase xt-8" subwoofer driver in a custom box. Just wandering if anyone has every used this amplifier before, and if it runs any good for the price of £60 that i got it for.

Im not sure if it will be somewhat matched to my dual 2ohm coil sub. Internet says it has 300w rms, however im inexperienced and don't know if that means 300w rms per coil, or 300wrms to both coils.

Each of the amplifiers two channels are apparently rated for 2x 225w RMS at 2 ohm. or 1000w MAX at 4 ohm(bridged). So, what could be the best way to wire this up? I think i could either:

• wire the left channel to one of the coils, and the right channel to the other coil, making sure that the left and right channel are both at the same phase, this seems a little risky though

• bridge the amplifier channels (they are bridgeable) to get 1000w MAX at 4ohm, then wire both the 2ohm coils to get 4 ohms, and connect that to the bridged 1kw max output.

Would love any advice, thanks

from any few models like 704S2 and 804D3 I have found the repair manuals online (go to
https://static-pt.com/modelManual/BOWW-704S2_sm.pdf?v=1670948438555
and the last attachment) unfortunately not from the model 703 (first series, manufactured between 2003 and 2008 ser.-No 0013830)
Maybe one of the members can upload this manual - thank you very much.
A friend of me note, that the bass drivers has failed and when the membrane is moved by hand, it works for a short time.

I have aquired a Cambridge Audio A5, it hasn't got an internal phono preamp fitted, is it possible to use an external preamp between the turntable and the amp phono input.

Thanks for any help

I'm interested in building some sort of single-ended triode tube amplifier, probably in a mono power amplifier format. I know enough to know that 15W is a lot to ask of a SET amp, but not enough to know how feasible or infeasible it is. If my expectations need readjusting, then please, adjust away.

I just got an Adcom GFA-535II for free in good cosmetic condition.

F603 was blown so I replaced it.

I did the bias adjustment.

There's -1.79Vdc across the left channel speaker terminals.

There's also -483mVdc across the right speaker terminals.

Is there a part known to fail that would cause this?

I got a HK980 for cheap today. I have a modified HK670 ( https://www.diyaudio.com/community/threads/hk-670-integrated-amp-sim-mods-etc.384245/ ) that I like, and this has the same power amp so I could not resist.
Owner said it goes into overheat protection randomly, but works fine other than that. I tested it abt 10min when I picked it up, and it worked fine. Did not heat up, and owner claims it's not hot when it goes into protection either. Based on this I guess there is a problem with the detection circuit, and not bias. Seems to be a NC temp switch that is connected to an input on a processor. Pictures below.
I have not opened the amp yet, thought I would check if someone here has fixed the same problem before, because it seems to be a common issue with these? If not, I will post what I find when I get to it.

I’m a little stumped on this so I’m looking for help. I wired up an Engl style preamp on the bench to mess around with this weekend, just 4 stages with 2 12ax7. Something sounded really unpleasant at all gain levels so I started to probe around and noticed these weird notches in the signal on the plate of the first stage. The positive one seems to correspond to the voltage level at which the next stages grid starts to conduct; the negative side notch mirrors it.

Now, the notch isn’t present on my guitar or the signal generator I’m using. it’s not present at the grid of the first stage at any gain or signal level. It matches the input frequency and while there is a lot of high frequency noise in my house this particular pattern isn’t there with no signal applied. It sort of fades in as the gain knob is turned up which is part of why I think it’s related to grid current. I added a big 470k grid stopper right at the socket (note that there is always a 100k in series anyway) and the notches got smaller but never really disappeared at high gain when viewing the first stage anode signal. And obviously it’s still there at the grid of stage 2. I also pulled all the cathode bypass caps. I thought blocking distortion but the DC level at the grid isn’t going negative much at all in overdrive conditions. And frankly, I’ve built a lot of tube preamps and I’ve never seen notches like this.

Oh, and oscillation is a possibility. The circuit isn’t fully stable at all gains and guitar volumes. But when it does howl I can move wires and affect frequency but no wire manipulation affects the notches in any way. They are there all the time.

I know the Engl schematics are famously incomplete but I figured I’d start with the basics and tweak it myself. Here’s a reference file, all I have is from the input jack to the tone stack and I’ve omitted the switching around R10 and the bright cap.

Hi.

Yesterday I took 6 pieces 2SK170 from Segor Electronic ( shop in berlin ).

There are still some on stock. Price 1,2E ( per piece ).

https://www.segor.de//#Q=2SK170%3BImport&M=1

I measured all and Idss in range 5,3 - 5,8 mA.

Best.

Hello everyone
Recently I've received a TEAC car amplifier for repair and at first glance just the output stage of one the channels was damaged.
Upon changing damaged power transistors with new ones from the same batch and applying power the amplifier was again shorted and went into protection mode.
Then I investigated further and found the presence of voltages near the rail voltage at the base of the power transistors and as soon as you apply input the final stage driver transistors BD139/140 will die and short out causing the amplifier going into protection mode.
I checked every single components in and out of the circuit and compare their value with other channels and couldn't find any noticeable difference between them.
And of course I check the input decoupling capacitor and it's not shorted.
I also tried changing all the transistors in the preamp section and still no luck.
Can anyone help me and explain what could cause such a fault?
Thanks in advance.

I need 4 of the 34R and 8 of the 68R. Can be a couple R either way.

Non magnetic tantalum like Shinko, Audnote, Rhopoint GG102 etc. or something else equally wacky.

I replaced the output transistors in my Sherwood SEL-400 because one was bad so I replaced all four. I hooked up a turntable and headphones and it was working fine until I tried to take some voltage readings and must have shorted the test lead. A stream of smoke rose from the driver board left channel so I immediately unplugged it. Several resistors burned to a crisp, one ceramic cap is charred, at least one driver transistor is shorted and both output transistors are toast.

I'm going to use this as an opportunity to learn more about this amp and rebuild the driver board. The three transistors and three electrolytic caps (per channel) are on order but I am unfamiliar with the remainder of the components so I'm hoping to get some guidance in identifying them.

Ceramic Capacitors

Although they seem to be from the same manufacturer, they don't appear to have consistent nomenclature.

C703....schematic reads .02.....cap reads "RMC .02 20% Z5U" ( .02 uF, 20%, Z5U ? )

C704....schematic reads 820.....cap reads "RMC 820 10% Z5F" ( 820 ? Z5F ? )

C705....schematic reads 4.7.....cap reads "RMC NPO 4.7 10%" ( 4.7 uF, non-polarized, 10% tolerance, voltage? )

C707....schematic reads .01.....cap reads "RMC .01 80-20 Z5U" ( .01 uF, 80-20 ?, Z5U ? )

C720....schematic reads 47......cap reads "RMC 47N750 10%" ( 47N750 ? )

C724....schematic reads 2700..... cap reads..."RMC .0027 10% Z5F" ( 2700 pF, Z5F ? )

Red Capacitors
(what type are they?)

C701....schematic reads 10uF 35V......cap reads "10 35V" one leg has + signs

Rectangular Capacitors
(what type are they?)

C721....schematic reads "0.1"....cap reads "250 .1"

C722....same as above

Green Capacitor
(what type is it?)

C723...schematic reads "0.22 250V"....cap reads "MSH .22/K 250V"

Resistors

the values are on the schematic and I will verify the color codes, I just need to know what type they are and wattage

View attachment 1304599View attachment 1304600

I have a modified Quad 33 which I use with various sources - turntable through the disc adapter board set up for Shure V15 III, cd through Radio input with 6.8k series and 3.3k shunt resistors for (I believe) 10db attenuation, and DAC handling signal from computer through the Tape circuit. If I set the adapter to H the level is lower than cd, and on M it is slightly too high. Can I change resistors on the adapter board to adjust to the same level, and if so, can anyone point me at the right ones to save me the task of puzzling it out (I'm not very good...)

Hi I have an ADAM A8X amp, I'd like to try to replace the 2 (or more) large capacitors that are buldging. They are 4 large capacitors of the same kind in a cluser, I'd like to replace them, need some help identifying them so I can order the right kind. I can post some pictures.



ADAM A7X/A8X AMP REV C2


If anyone can provide a schematic or info that would be great thanks!

I have a pair of Seas P17REX-H H499 08s woofers for sale. These have been in storage for quite a while, but both work well. Located in Australia, but can ship anywhere, if postage is covered. $150 for both + shipping.

Cleaning house. These are older parts (except for the Chemicon caps). All parts + shipping. PM for questions.

Make offers. Help me clean the shelf!

Prices updated.

Qty 2 Duelund Coherent Audio Inductor 0.9mH - $95 / Pair 1 pair available
Qty 2 Duelund Coherent Audio Inductor 5.0mH - $145 / Pair 1 pair available
From Duelund - "Originally made by Duelund during the design phase of the Gryphon Poseidon system."

Qty 4 Nippon ChemiCon 47,000uF / 80V Caps with mounting brackets - 2 years old. Used - great condition - $25 each or $90 for all 4.
Mfr P/N E36D800HPN473ME92M
NOTE: Current version at Mouser is appx $42 each for these.

Sell linear power supply with dual output selectable between 12, 15 and 16 vdc.
Additionally can sell Gotham star quad oyaide terminated 1 Mt..
No original pack(thin box) but will make very good packing. Price 280+ shipping

Welcome to the 'Inner Sanctum', the complementing secondary volume for a woofer alignment in a 2way or 3way consisting of 1.5ft^3 gross. Stand mounts preferred, but not required.

No cost limits of any kind, nor xover limits, nor restrictions on what drivers to use. If you have them, use them! Passive xover implementations only, please, for this challenge, but entering the challenge is not required for attendance if more than observing. Limit one challenge entry per person.

Photos or drawings of internal construction must be provided for verification as visual inspection will not likely be possible. Simple large window braces or simple large holes do not conform to the dual chamber specifications. This should be specified as a vent, PR, driver, or air flow restriction between the 2 chambers in the most common definitions.

Basically, the woofer alignment must incorporate a dual chamber arrangement. This allows isobaric, 4th or 6th order bandpass, Augmented PR (noted in the LDC), multichamber aperiodic(MAPD), dual (or more) chamber bass reflex or DCR+, HPAS, or any other dual-chambered or more arrangement. Feel free to do the same with the optional midrange if you wish, but it is not required, nor will it take the place of the required woofer envelopment.

Since multiple woofers can be used, 2 different alignments or one for each woofer can be applied. They do however have to be different alignments if both woofers do not share both chambers. However, using a pair of woofers in the same plane will require it be a 2.5way, no matter either TMM or MTM. Same plane dual woofer 3ways, or 3ways with dual woofers facing externally are not allowed. Dual external woofers are for 2 or 2.5ways alone.

Dual transmission lines are also allowed via a single driver like the Bose cannon, or dual driver while following the above rules.

Stubbed vented alignments, as in 4thtry's Plummer's Delights from the Nano challenge a few years ago are allowed, BUT the stub chamber and port diameter must not be of the same shape or cross-sectional area. This constitutes 2 chambers, and therefore is allowed.

I look forward to your experiments, and the outcome of this challenge.
More about event will solidify as things happen, likely near end of year (Dec) or beginning of next year.
See you there next year,
Wolf

I am new to all this, but reading forth and back on this forum, I can read many places, that adjusting Tracking bias and Focus bias usually end up somewhere around the point where the two coils stay silent.

My question is this: How silent is silent?
Is that dead silent or is it a point where they go from loud and clearly audible, to a far suppressed noise? Is it a level where they give a very damped little sound if one put's ones ear to them? Or something else?
I am not speaking about the adjustment itself as a read out on an oscilloscope.

I am very interested in hearing about this.

More specifically, the lasers in question are Sony KSS-140 and KSS-151a, but also on a more general level.

Kind regards,
Jacques

I need to make external volume control. I'm connecting mixer line output to PA mixer Mic input. The input level is too high for the PA to handle so I need to control it because the PA preamp has volume control after the preamp circuit, not on the input socket. Hope I make sense 🙂. My guess is that 100K log pot should do it .
But the mixer output all ready has a volume pot but I don't know what value it is so I'm thinking using 100k after it shouldn't put too much extra load on it?

I have a troubling noise issue that I spent a fair bit of time diagnosing today. My amplifier (3e audio unit) is installed in my car, and is fed by a dc boost module to go from 12v to 48v. The amplifier is fed by a DSP, which runs on 12v. Because the DSP has single ended RCA outputs (not balanced), I modified the amplifier to accept the single ended input. I am getting a roughly 20hz tone (I think this may be PWM noise by a component in the car). My question is, is it possible the noise is being caused because the RCA cable signal ground is grounding to the 12v dsp and the 48v amplifier?

Here are the combinations I tried that made me suspect the signal ground:

DSP>3e amp=noise
Phone with usb c to rca converter>3e amp=no noise (rules out issue with amplifier)
DSP>amplifier/speaker outside of car (with long rca)=no noise (rules out issue with DSP)
DSP>commercial car audio amp=no noise (I'm not sure if car audio amps run fully on 12v throughout? Or they manage the signal ground differently?)

I also did several other things like run the dsp from a different 12v source to eliminate ground loops, tried different RCAs/shielding etc.

Another thing that makes me think an issue with the signal ground is that when I insert the RCA into the amp while it is carrying a signal from the dsp, I can start to hear the music when the middle signal pin makes contact without any noise, but when the ground connection is made the noise starts.

Any help would be greatly appreciated, I am stumped on how to address this!

123

I would say most speakers reproduce much less than that range, and so does most people's hearing and most music recordings as well. Perhaps for a speaker to be a good audiophile or PA speaker it should strive to reach 20k, but very few systems or recordings will have a decent response down to 20HZ.
That can be good for movies and such, but just like the top octave, the bottom (20-40Hz) is pretty pretty unimportant for most music. In my experience a HPF around 40Hz often sounds better because the information down there just contains crap that takes up headroom, and demands a well treated room to not be a total mess anyway. My subs are designed go down to 35Hz, which I think is perfect for most music.

My point is really that a lot of people tend to assign a lot of importance to those extreme ranges even though they are a very small part of the listening experience. You can make an really amazing sounding system that only covers 50-16k, and there are many bad systems that cover 20-20k.

I prefer transient non-linear low end/bass compression, added harmonics to high end/ treble and non-linear limiting with my music. Essentially, tube pre-amp goodness.
But I want to accomplish it without the tube hassle and limitations. Please let me know any available good DSP solutions that can authentically simulate tube sound, and allow tweaking of the parameters.

Hi guys, I have a problem on a precision power a600 amplifier.
Basically the amp came to me not working, I saw that one bank of transistors had components the other totally different, not having an original schematic to refer to.
I think the 4 npn bdt 81 and bdt 82 are original (the other bank mounted bd711 and bd712).
I would like to know what original amps it mounted ee above all it did not come to me complete, but transistors were missing.
I enclose the photo of the amplifier by circling the parts not present of which I would like to know the abbreviation in order to install them corettamente on the net I have not found anything about it.

Some of you may recall years ago when there was inventory of the Sony
VFETs still to be had in Singapore. After purchasing some (soon to
appear here on diyAudio as the last of the DIY Sony VFET amp kits)
I posted a note advising people to buy some while they still could.
Those people are probably happy they did.

Now it looks to me like the inventory of Tokin VFETs (2SK180, 2SK182 and
THF51S) will follow the same path. The stock is limited and they aren't
making any more, the Fukushima event having taken Tokin out.

I am contemplating a couple of projects using them, and I advise anyone
who wants to play to acquire them while you still can. All three part
types are usable and most applications would not require matching.

On Ebay watanabletomoaki and pras1170 are known reliable sources.
At this time tomoaki has the lower price at $60 each.

What are the differences and which one would your prefer or suggest? Thank you!

Is there a more accurate way of determining slot port length with end correction for a subwoofer enclosure than the method explained by JL Audio in the link below? It seems that their method is just a ball park way of doing it but I would prefer a more precise method. The enclosure will be pretty big, made of 1.5" MDF, and I hate working with MDF because the dust gets everywhere so I don't want to have to remake the enclosure.

https://jlaudio.zendesk.com/hc/en-us/articles/221068047-Enclosure-Ports

The Enclosure specs will be 2.5 cu.ft. net volume, 3"x13" slot port, tuned to 32Hz, 3 shared walls on port.

According to the tuning formula shown in the JL link above and solving for Lv this port should be 35.87" long. How can I determine what the end correction is and how the end correction will affect it?

Also, will flaring both ends of the slot port with a 1.5" round over bit affect its length similar to how the flare on a round port affects its length?

Hey Guys,

I have bought a £400 DBX Driverack PA 2 and I think it is very good value. DriveRack PA2 | dbx Professional Audio

The DSP section for crossovers Eq and room correction is really superb.... But the A to D and 6 channel DAC's are not great. There is no digital input, only analog, so all sound sources are compromised both on input and output.

I am looking for someone with PCB trace cutting skills so I can access the digital input and digital output and allow me to use my own high end AKM A to D and 6 channel AKM DAC's.

Can anyone help me....?!
Thanks.
Alex.

Can anyone identify the Noble (Taiwan) potentiometer shown? I find nothing on the web and messages to Noble have gone unanswered. A datasheet would be helpful if someone has an old catalog from late 90s to early 2000s. I am looking at Bourns now to see if something that's close will fit.

I am developing some vibration reduction feet named the Vibration Black Hole (VBH) for Vera-Fi Audio. It uses several stages of viscoslastic gel damping combined with changes in material density (aluminum to stainless steel to nylon) to produce mechanical impedance mismatches that enhance the loss of mechanical energy transmission. The feet are 50mm in dia and 33mm high. They are designed to be used with spike feet that contact a conical depression in the small black nylon pisto st the top. Self adhesive spike can be provided for installation on the bottom of the piece of gear. The feet work not only in the axial direction but also laterally (radial).

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I set up a test to measure the attenuation of an impact to a table that is then transmitted to the plinth of a TT. By instrumenting the plinth with a piezoelectric transducer, we can measure the transmitted energy from a mechanical impact to the table. I use a special instrumented hammer fitted with a calibrated transducer (PCB Piezotronics, ICP Impact Hanmer). This way, we can quantity the hammer impact energy for accurate comparison.

This is the VBH:




Here is the setup - LSA TT, Owon digital Oscope, PCB Piezotronics ICP hammer and signal conditioner, disc piezoelectric transducer mounted on plinth.


The piezoelectric transducer is mounted to the plinth with 3M thin double sided tape at the 1/3 and 1/3 position to avoid the vibrational nodes:


This is the instrumented PCB Piezotronics ICP hammer:


Here is the Oscope trace without the VBH. Yellow trace is hammer strike energy and blue trace shows the time response of vibrations in the plinth:


Here is a closeup of the VBH installed with a spike foot under the stock feet:


Here is the Oscope trace with VBH. Note that the hammer energy is approximately the same at around 24.6Vpp. The transmitted vibration is reduced in amplitude but more importantly, the high frequency resonances are smoothed out. The VBH will help to dissipate impulsive energy (taps, bumps, etc,):

Recently got one from AudioAdvisor, a place I have bought stuff from for decades. I saw all sorts of reviews, either rating it as trash, or the greatest thing since sliced bread.
Knowing Audio Advisor would do me fine I bought it. Apparently it has a devil of a time hooking up to wifi, it sole mission besides streaming. Whatever I decided to scale the learning curve. AA gave me a phone number to a tech crew from Bluesound. Called, prompted to hold for help all helpers busy, then finally message to leave message and get call back. Which they did, but next day while at work. Oh well, AA has been great, offering refund up to 60 days, refund now, they advise to scale learning curve to get it to work. Allegedly if tech crew cant resolve, they have some main dude number for last resorts.

Now the question. I suspect my unit is dead! It will not hook up to wifi. The rest of procedure works fine, app finds unit, just some error preventing hooking up message.
After a while, light turns red, which I understand is bad. I am close to router, I even tried hard wiring it with no luck.

Anybody else out there had this deal to go through with this unit, and save me headache? Either this unit is defective, or some simple problem?

Oh well.

Russellc

Hi. FS CD-Pro2 VAU1254/31LF CD Player Assy - NEW, NEVER USED. Now almost impossible to find, this unit was pought years ago as spare, but was never used, still in its box.
This is the version with spring:The four corners of the rack are equipped with spring supports, suitable for installation.

Asking same price as I paid (still has the original invoice), a similar item is selling for 500U$ on ebay, but you can't be sure that's the real thing, mine is...

See pictures for details.

Asking 400U$ + Shipping + 3.5% Paypal fee

I would like some comments from people who have experience with either of these two woofers. The application is a sealed box with Linkwitz Transform bass EQ, using the woofer up to about 300 Hz.

Both woofers seem nearly equivalent in performance (on paper), and are nearly the same price (in North America). I am looking for some real world commentary, experience, opinons on these drivers... Thanks ! .... j.

I need a speaker selection switch and have read many posts. Most recommend niles, russounds and adcom, becuase they have components that protect amps and speakers. I don't understand why I need that protection. It seems that, since just a pair of wires are used to connect an amp directly to a pair of speakers, it seems only a simple switch, with two wires from amp and wires from two sets of speakers would be needed to connect to a switch. I don't want volume control. What am I misiing?

Thanks

Hi all,

so it is not exactly about amp design, but I would appreciate some help and shared experience with a tube amp shipping. So I bought a line magnetic Lm-518 amp. The amp was offered for a pickup without any box. My friend got it for and now I need to figure out how to ship the beast. It is ~80lb big amp and I have no idea what would be the best way to pack and ship it across the country (US). Maybe you have some experience and know where to get packing material and what would be wrapping techniques. I appreciate any help. Thank you! Here are the pictures, weight and dimensions: https://www.hifi-amplifiers.com/en/...class-a-singleended-amplifier-24w2-p-869.html

I took a brief survey of solid-state power amplifiers as reviewed by Stereophile. I chose one point, THD+N at 20KHz into 4 ohms at roughly 20V. These are demanding conditions. Stereophile's measurements are:


The distortion measured in commercial amplifiers is roughly an order of magnitude higher than the simulated distortion numbers seen on this board. I can think of several reasons why simulation may be optimistic:

• Test conditions are easy: 1KHz where the loop gain is high and 8 ohm load.
• Complementary devices are perfectly matched.
• Bias current is optimal. This ignores that the amplifier will be hot.

Some commercial designs have enough distortion to be audible, but I don't think they are paying less attention to distortion than hobbyist designs. I also don't think the simulation will be off by an order of magnitude if given realistic conditions.

What do you think? Are we living in a bubble?
Ed

Morning, just turned 68 and discovering the joys of Social Security and having the time to work on long neglected audio projects.

The first was refreshing the crossovers caps in my Klipsch, RF-3s. With the great help and guidance from the members of the Klipsch Community, they now sound as good or even better than the day I brought them home, 21 year ago! The second oldest component is my over 20 years old Rotel, RCD-991 player. For the last few months its been acting like its laser is on its way out. Symptoms are; the draw reopening several times after initially loading a CD, going to “Track 10” instead of “Track 1”, and taking significantly longer to boot a CD. All these symptoms seem to cure themselves after its been running for a few minutes. The laser warms up and it functions normally. I’ve already cleaned and renewed the lubricant on the rails, gears, and tray, but while the tray is a bit smoother, the other symptoms are still there. I can’t be too surprised or upset, I gather the lasers are only good for about 10 years, so I guess it was about due.

The laser is the KSS-213B that seems like every vendor in the world sells, even Walmart lists it, LOL! The options are buying just the laser unit, KSS-213B or C or the complete mechanism, KSS-213CL, which includes the laser, both motors, and drive gears. My mechanical instincts tell me to spend the extra cash and renew the complete laser drive unit. Either option looks like a pretty simple straight forward job. Anybody here lend me some advice or experience replacing a laser? And recommend a good vendor to source the part or unit from?
Thanks Gene

I originally bought this amp back when it was the cool new thing. I remember upgrading coils and things, but sorry, I don't recall the details. I have used it on and off over the years. The volume pot is currently disconnected.

Includes the original power supply.

$60 shipped within mainland USA.

Payment via PayPal.

Thanks

An Idea for an Audio Men's Shed

Ideas for a Men's Audio Shed SIG (Special Interest Group). Continuing in the article below I highlight a project I’m currently involved in at my local Men's Shed Association. Should my idea be of interest to you, may I suggest discussing it with your local association before posting comments. Meanwhile, I have pitched this idea to the UK Men’s Shed Association who may, or may not, broadcast this idea to their members - awaiting response.

Firstly, I am designing an enclosure for DIY Hi-Fi loudspeakers and I will build a pair with the help of my local Men’s Shed. I thought that if I share the enclosure’s schematic and construction tips with other Men's Sheds worldwide a made to order flat-pack package could be made available on request for local pick-up. Such an activity may, or may not, become a revenue opportunity. Personally, before anyone asks, I’m avoiding scope creep and don’t plan more than one or two designs. If you think this would be a good project for you local Men's Shed please share this information and ask them to pitch this to the association, should mine get overlooked. In the near future I'll post my proposed enclosure design in the Loudspeaker forum.

Secondly, I am also in the process of designing a 10 - 20W amp to power the speakers. Again, I thought that if I share the schematic with Men’s Sheds who have a member with knowledge of using a multimeter, to assist testing a completed amplifier, this might be an opportunity for those with an interest in an audio electronics project. I must emphasise that this second project is very much work in progress! I have a design I’m testing with a Spice simulator. Should any reader be willing to give concrete input to conclude a design, or donate a design, I’ll create a new discussion in the Amp forum. I aim to create a schematic with a level of completion that would include test points/nodes and values for testing.


Thanks for reading.

Hi everyone, can you help if you can🙂 Looking for an onkyo tx-sv919thx service manual. Thanks.

This headphone amplifier is based on the Tori amplifier, which name seems to come from an agressive dog.
I hope to have tamed that dog, hence the name 'Snuggles', Simulating the amplifier in LTspice was not easy for me to get right. I probably should have called this amp 'Struggles' instead of 'Snuggles'.
Anyway, I am planning to build it using a NE5532 or similar, but what do you think? Does it have a chance of success?

Have to reduce my collection of tubes to concentrate on the onegoing projects:

one Lewis & Kaufmann 100th 40€

one RCA 826 40€

one RCA 828 40€

one Telefunken 612 40€

one ATS25 20€

one Hytron HY61 20€

three!!! Heintz & Kaufman 254W 60€ each

two!!! QE08/200 very similar to 7378. Tretode 60€ each

price excl. shipping

I just bought a second hand 18 Inch Sub. It is a closed box and uses the BMS 18N850.

Hypex FA251 is my amp. So I have three presets 100/90/80Hz low pass. But since I hear so much more bass than with my previous 15 Inch...I wanted to look at the crossover settings again. Maybe boost some freq so playing music with lower volume sounds a bit fuller?

I know these are all vague requirements. And perhaps there is no rule of thumb. And one should just play around with it and see what works in my room. etc.

It's just that I wonder what do other folks do that have an active sub with a dsp.

I have 3 of these spare.
£5 each. JLCPCB 1.6mm
Nice CRC PSU with the second Cs being isolated for L/R channels.
Credit to Jeff Young for the layout and sharing the files.

A pair used but verry good condition the contact wires are about 50mm long.Little sign of use but top condition.price 50 euro/pair plus shipping inside EU.

I'm working on the final details of a speaker cabinet.

I'm using B&C 12FHX76 coaxial drivers. I want to hide the speaker flanges, so my idea is to make a plate that covers them, giving the speaker appearance of a rear mount. This idea is about improving the appearance of the speaker, but I want to make sure that it doesn't have a negative effect on sound quality.

I've seen a variety of opinions on the subject, but I don't see any clear concensus. So I took some measurements. Measurements are "raw" data, meaning no EQ. Measurements are taken 18" from the driver, and the microphone was not moved between measurements. (I did time-align the woofer and horn, but that is all.)

I'm attaching the REW measurements in case anyone is interested in playing along. I see small differences, but I don't know either has a problem that I can't fix with DSP. I'm not sure if there is a particular piece of data that would stand out as a problem, so I'm throwing the entire files up for you guys to look at.

-The first measurement is the driver front mounted to a flat baffle.
-The second measurement has a secondary baffle that covers the perimeter of the driver, so it is concealed like a rear mounted driver. This secondary baffle has a 1/2" radius around the driver.
-The third measurement is the "front mount" driver with EQ. I don't see any glaring issues with the post-EQ measurement either, but I'm not an expert.

What do you think? Is one meaningfully better than the other?



My prototype speaker with the "front mount" secondary baffle attached. Just a test. I won't build the cabinet like this.

Is it worth invest in expensive cap, inductor and resistors in notch filter for fullrange driver? Example Mundorf oil cap or litz wire oil inductor

This is a handy and affordable little dual-polarity output module that's available on Aliexpress here for about $5. I
should point out that I bought mine on Taobao but the modules look to me to be identical whichever platform you
happen find them on.

I fired this up and made a few measurements, primarily I started off looking at its efficiency. The quiescent is
decently low (10mA or so) but delivering around 4W of output at +/-24V I found the efficiency rather dismal
for a switcher and definitely lower than as advertised on the vendor's Ali page. I was getting about 55% which
meant around 4W was going somewhere - initially I wasn't sure just where. I figured best to wait a while and
then poke around with my finger to see what was getting hot as 4W wouldn't be possible to hide for very long.

It took less than a minute to detect that the toroidal inductors were to blame, everything else was cool. After
extracting them and taking the shrink jacket off one, it looks like this :



My LCR meter confirms a nice low DCR but at 100kHz, the resistance is close to 3ohm indicating
high AC losses. The switching chip operates at 180kHz so obviously this particular material isn't a
great choice in this application. From its colour scheme (yellow/white) its probably a type 26
which is about the cheapest toroid going, a great choice for a CLCLC power supply filter but
unsuitable for high frequency work. I have quite a few different sizes of Sendust cores so why not
try some of those, they're much better at HF.

Before that though I wanted to see if I could understand the schematic, a switcher with 3
inductors isn't something I've encountered before.

I've been on the hunt for a thin, fabric-sleeved instrument cable, something in the ~5mm range. The thinnest pre-made cable I've found is from CNZ Audio at 6.5mm. I was going to make my own with Best-Tronics CA-0678 cable, but I'm not sure which braided sleeving material to use - i.e., nylon, TPE, cotton+PET, etc.. Any recommendations?

I am trying to figure out what the differences are between these tubes. According to the valve museum the a2134 is the “commercial” version of the n78 but the data pages they link to look like very different tubes. Various places on the internet say that the n78 is similar to an el84 with a different pin out. I dunno, the data sheets kind of line up but not really. I saw an old discussion on here with @7N7 saying that GEC could be really generous with their ratings at times. Oh, and as an added bonus, how does the cv4062 figure into this? The valve museum says that they can be a “sensible” substitute for the a2134.

Recent mention of the 6s19p 6S19P Push Pull Build has me intrigued with that tube's characteristics and low cost.

A thought experiment - 6.3v x 20 = 126v.

Could you series-string the filaments of 20 6s19p tubes, to feed from standard ~+/- 125vac? Seems very appealing compared to a high-current 6.3v filament transformer.

I know that series-stringing filaments was super common in cost-cutting designs in the mid-to-late consumer product vacuum tube era [and often required tubes with appropriate characteristics for the series arrangement] but I have never heard of someone doing a series string of a ridiculous number of 6.3v filament tubes

Picked up a PL-5 for cheap to gift to some friends. It had the "speed wobble" where it changed speed on its own, wouldn't hold speed and was just off. Normally, I simple fix, open it up and deoxit a bunch, work everything, reassemble and its good.

Did all that, got it back together and plugged it in. It started on its own, and the motor is spinning back and forth and stop button isn't working.

Pulled it apart, realigned everything, worked all pots again and am letting it sit and dry now.

Any advice on potential causes? I've checked mechanical alignment several times, have the service manual and didn't break anything.

Links to improved models are at the end of this post.

Greetings and Merry Christmas. This post will be edited as better information is found.

In the latest update of LTSpice (version 4.22k) Mike has responded to requests from multiple people including Bob Cordell, Ian Hegglun and myself to improve the accuracy of the MOSFET model.

At low currents, lateral and vertical MOSFETs operate in what is called the subthreshold conduction region. In this region, Ids responds to Vgs exponentially like a diode, rising a decade for every so many mV (typically 60mV for Si diodes, but 200-300mV for MOSFETs).

Until now, LTspice has not modeled this region of operation well. Because class AB power amplifiers and low-power MOSFET buffers operate within or close to this region, many audio circuits were not modeled very well and the simulations did not agree well with real life, or had noisy results due to sharp edges in the derivative of the transconductance curve which caused an impulse whenever moving in and out of the subthreshold region.

At the same time, alternatives such as the EKV model did not do a good job at modeling the highly variable junction capacitances, where VDMOS is needed. Now that the VDMOS model has a good subthreshold conduction model it appears we can bake our cake and eat it too.

It was beginning to appear we would need to make complex and non-user-friendly subcircuit models to achieve this, but Mike has stepped up and improved the internal simulator model so that the improved models will integrate fully with LTSpice and be available in the model selector.

We don't know for sure yet exactly how accurate the subthreshold curve in this model is to real life, we will have to see as we go along.


Some things to keep in mind:

• Current models without subthreshold conduction parameters will not automatically take advantage of the new model functionality.
• The original 'subthres' parameter, is left in for models that still use the old subthreshold model. For new models ksubthres should be used. See below for some of Mike's actual comments on the model.
  
• The 'ksubthres' parameter if present will determine subthreshold behavior and cause the 'subthres' parameter to be ignored.

I've attached an image that shows the effect of the 'ksubthres' parameter. The 'subthres' parameter works in a similar way, just using different values. According to the discussion on the LTSpice Yahoo group, 'ksubthres' should be used instead of 'subthres'.

The improvements in the model will be applicable to vertical (IRF240...) and lateral (ECX10N20...) MOSFETs and should be an improvement on even the best current models. If you can measure Ids vs. Vgs in the subthreshold region, it should be possible to augment current models with the new parameters. Needless to say, such models are in the works, but don't let that stop you from trying it out.

I've collected some of the comments made by Mike on the model:

Mike Engelhart said:

BTW, I've changed the device equations for VDMOS subthreshold. It uses
a new dimensionless parameter Ksubthres. It will accept the old parameter
and match Id at Vds=1V and Vgs-Vto=-1V. The new VDMOS equations should
be now be continuous in value and all derivatives everywhere. I changed
the subthreshold equations so that it would cooperate with another
undocumented parameter, theta, which adjusts mobility on Vgs.

--Mike

Subthres was a spline fit and how it fit depended on many things. Don't use it
any more. Use Ksubthres instead. Ksubthres remaps the Vgs numberline so that
that there's now a unified subthres, linear and triode region.

​

--Mike

Click to expand...

Links to improved models:

• Alfet/Exicon/Semelab 10N20, 10P20, 20N20, and 20P20 lateral MOSFETs
• DN2540, DN2530 (In the zip file)
  
  Vertical MOSFETs:
  
  
  [*]IRFP240/IRFP9240
  [*]IRF640/IRF9640
  [*]IRF610/IRF9610
  [*]IRF710
  [*]IRFP340/IRFP9140
  ​
  
  

Parasound HCA-2200II & HCA-3500 power amplifier fuseholders; will fit other models as well. These are leftover stock from when I did warranty repair for them. One pair available for free... just pay the First Class shipping. I cannot respond currently as I am locked to no more than 5 message replies in an hour (!??). Please pm me and I will respond as soon as I can.

Good afternoon

I'm working on a Sundown Salt 400.2. The output section is damaged. 2 diodes marked A2 are toast. Is this a 1N4148 diode in SOD123F package? It measures 1.75mm x 1.25mm and has the flat narrow leads. The data sheet I'm looking at lists the 123 package much larger.

They were connected to pins 1 (VAA) and 6 (VSS) of the IRS2092S. Locations D7 and D8 in first pic. 2nd pic is of other side. Easier to read the diodes.

Thanks in advance!

What types and brands are there on the marked with such tweeters?

In the moment I know only the MT320 (MT 320) from Ciare (only 96 db, but still more than the average) and a RCF TW-116 based tweeter from German brand "Glockenklang" go to
http://www.soundland.de/catalog/images/products/tn/20/203545-350x407.jpg
and
http://www.diyaudio.com/forums/mult...glockenklang-phenol-99db-based-rcf-tw116.html

Please note, I know the most magnetostatic tweeters like "Stage Accompany" SA8535 and different Alcone versions - I search only an overview about dome tweeters without metallic diaphragm material and very high sound pressure level without horn.

Thank you for your advices

Got a trio of JBL 2226H 15" drivers that I need to either get rid of or use. I don't have time for a major project but if I could make a simple 2-way like an econowave or something similar and maybe just save the last driver for a spare.
So:
1. Make a 2-way party speaker
2. Sell the drivers and put the money towards my PM 90 project.
3. Other
Thoughts or suggestions are welcome. Thanks

I was wondering whether anyone else using MiniDSP hardware like the SHD, SHD Studio etc are seeing this when they run a room calibration.



When this occurs Dirac will not correct for phase or delay. This problem started when I updated to Dirac 3.9.7 from 3.8.2 which worked fine the last time I used it a few months ago. I have always used my UMIK-2 with Dirac without issue. I subsequently reverted to 3.7.3 and continued to have the issue until I switched to my UMIK-1 mic and I was finally able to do a calibration which seems valid. (Not one of my best outcomes however)

The UMIK-2 works fine with REW, HolmImpulse and audiotester.de., but suddenly not with Dirac.

I previously owned an SHD before replacement with the Studio a couple of years ago, and have a lot of experience with doing Dirac calibrations. I never had any problems until a week or so ago when a hardware replacement (Danley DNA SC48) dictated the need for a recalibration after I completed configuring it. (I did a lot of measurements with the UMIK-2 during that process and had no problems with it.)

Dirac provides access to previous versions of Dirac as well as release notes for each version, but I have not found a way to contact anyone there about the problem.

More disturbingly there are reports of this problem on ASR going back to 2019 so it has been plaguing MiniDSP users for some time (also other licenssees). MiniDSP indicated that they were not really able to provide assistance in this matter, and to contact Dirac for assistance. (FWIW - maybe not much.)

Without functional Dirac the Studio is sort of pointless in a sense, although the digital pre-amp functionality is still needed.

And yes the room is not great, I've made a lot of improvements, but serious issues persist.

To check that a TDA7293 integrated circuit is genuine and not a fake made from a re-printed TDA7294 you can perform the following simple tests:

Using any reasonable quality 3.5 digits DMM set for resistance measurement (or the highest resistance range if it is not auto-ranging):
Positive probe to the metal tab and the negative to either pin 5 or 10 or 11 should give a reading of around 3M Ohms in the genuine device. Reversing the polarity should not show any reading. If you do not get these readings then the device is a fake since in the TDA7294 all these pins are not used (N.C.). This is a reliable test and the results are conclusive.

Explanation: Pin 5, 10 and 11 in TDA7294 are not connected (not used) but in TDA7293 they are used for cascading (and detection indication pin-5). Only the TDA7293 is capable of cascading to give more output power using multiple ICs.

Obviously there are more tests you can perform with a DMM but it is not really necessary, however, I will list them all the same:
+ve probe to pin 1, -ve to pin 5 should read around 4.5 M Ohms reversing the polarity should show around 8 MOhms reading.
+ve probe to pin 11, -ve to pin 1 should read around 8.5 M Ohms
+ve probe to pin 15, -ve to pin 12 should read around 12 M Ohms

Visual inspection of the suspected device often provides indication of counterfeited devices. Genuine STM device markings are laser engraved while a fake is likely to be printed. STM like most manufacturers nowadays laser engrave the devices in order to combat the counterfeiters. The laser markings often use unique or very distinctive fonts.

The TDA7293 is an extremely popular device extensively used in power amplifiers (Audio and non-audio) and in vast volumes by manufacturers ranging from the professional to the consumer products. This provided the fakers with the incentive to flood the market with fakes made from a re-printed cheaper device (and of lower performance) TDA7294.

There are plenty of genuine devices as well as fakes available over the internet (Ebay, Amazon, Ebid etc.). Buying in small or medium quantities is uneconomical from franchised distributors due to their operational and overhead costs. So here are a few simple rules to minimise the risk when buying on the internet:
1. Avoid sellers who do not show a CLEAR picture of the ACTUAL device. They have something to hide and do not be fooled by any commercial indicators such as trusted seller, to-rated seller, registered company, large feedback ratings, experienced seller, or a professional sounding name etc.
2. Do not buy devices that are printed.
3. Only buy devices that are laser engraved and carefully examine the provided picture.
4. You must reject the devices if they differ from the listed picture. This is your right by law and the selling medium (Ebay, Amazon, Ebid, Paypal etc) should support you 100%.
5. High price is not an indicator of authenticity. Quite often counterfeiters use a high-price to hoodwink buyers.

The thing to remember is that a fake TDA7293 device made of re-printed TDA7294 will work in a circuit but with lower performance. Also a fake device will provide output power when used as the first device in a cascaded configuration but the rest of the cascade will always be idle. In an audio power amplifier you will only notice that when you try to get more output power.

Attached is a picture of the genuine device to help readers see the laser engraved IC markings.

Hi!
What would happen if using thicker wire size for the internal hook up in the speaker?

How it sounds if wire goes thicker?

Thanks!

Hello,

I hope I'm posting this on the correct section!

This is my first attempt in designing a linear power supply and after a few days of intensive reading (my brain has melted) I've settled to this design.

I have too many questions to ask but it would be great if you could critique my design for starters... 🙂

Thank you all in advance!

Hi, I purchased a used 540 VA 18-0-18 V transformer and I would like to test whether it has operating problems under load. Not having armored resistors, can I create a load with a boiler resistor with the following characteristics? R 27.5 ohm, 1950 W, 230V. Rectifying 36 V I would have around 48V which with the 27.5 ohm resistor should make around 1.75A. It's definitely not a heavy load for this transformer, do you think it's enough to understand if it works well? Thank you

Hi,


Iam Looking for replacement/improvised amplifier boards for Denon POA 2400. Is there some one who makes replacement boards or modified boards with todays available components ?


Regards,
Suman

After decades of being behind the scenes, develpoing planar drivers for other brands, he's created a finished product.

https://www.consonusaudio.com/products

The tech section white paper has some intersting diagrams and radiation plots.

It's a wondermachine for women who are looking for a Telefunken U47 but had no luck ... damn good to massage your ears with the finest piece of music ever hit the earth (starts with some strange noise ..) :

Login to view embedded media

Hello,

Once again I have decided to throw my hat into the Ring known as InDIYana (Midwest Audio Club annual get together), and as usual, I don't really know what I am doing.

^The most important part of that is, my Wife has once agreed to drive 6 hours/300 miles across an International border to attend with me.

I must be thicker than the average bear, because I don't think I really understand all the rules, but Ben has said my plans for a coaxial tweeter/mid and pair of midwoofer isobaric style meet the theme criterion, so here we are.

Drivers are,

2x,
Sica 6,5 C 1,5 CP
Coaxial unit for HiFi and Studio Monitor
Code: Z004102
Nominal overall diameter: 6.5″
Nominal voice coil diameter: LF 1.5″ / HF 1″
Magnet material: LF Ferrite / HF Neodymium
Basket material: Aluminium Die-Cast
Power: 240 W
Sensitivity: LF 91.0 dB / HF 93.9 dB
Frequency range: 55-18000 Hz

4x,
Sica 6,5 H 1,5 CP
Hi-Fi / Studio Monitor
Code: Z004100
Nominal overall diameter: 6.5″
Nominal voice coil diameter: 1.5″
Magnet material: Ferrite
Basket material: Aluminium Die-Cast
Power: 240 W
Sensitivity: 89.4 dB
Frequency range: 40-4500 Hz

There is an overall plan (more of an outline) in my head for what I want to do, but most of the specifics are still to be worked out.

Baffle is to be 1.5" bamboo made from a stock shelf item at a local building centre, edges are going to get a 1.5" roundover, so with the woofers frame being almost 7", that gives me a baffle width of 10-11 inches'ish. Coax and woofer share the same basket dimensions. Coax will be mounted as close to the top of the baffle as possible with no edge treatment on the top edge.

Distance between woofer and coax will be whatever it needs to be. Not sure how much to chamfer backs of the baffle around the woofer for enough breathing room, nor how big the enclosure behind the midwoofer needs to be to attach the second isobaric woofer behind it. These two things will have a lot to do with overall enclosure height, and overall box dimensions cannot be determined until I work these two things out.

Box material will be a semi normal 3/4" Baltic birch box with separate chambers for coax and woofer sections, one solid brace between. Two removable panels on the back to get into box for XO, wiring, port tuning etc.. Veneer sides, either bamboo, walnut or cherry, not sure yet. No translam this year, too expensive, too time consuming and mostly too heavy,

Once I decide on how much the drivers need to breathe, then I can build the isobaric back chamber, then I can design a box around what those need to be. Not very good at planning all this out in advance, just take one step at a time and see where I end up.

My understanding of one of the major drawbacks to Coaxial speakers is intermodulation distortion caused by the woofer surrounding the tweeter, so I hope can limit its extension by crossing it over to the midwoofers beneath it around 400-600Hz. This will be instead of running the woofer coax full range (no high pass) and using the isobaric midwoofers as the .5 in a 2.5. I know sensitivity will take a big hit with this plan, but it's the plan.

Let the building commence,

(This is an isobaric build for sake of an isobaric build theme show and tell get together, please refrain from commenting on the general merits of isobaric designs)

I need new output transistors , as the old ones are shorted in one channel.

Original transistors:
2sc3856
2sa1492

What replacements could i use?
So far i have looked at :
NJW 0281g / 0302g
NJW 1302g / 3281g
2sc 5200n / 2sa 1943n
2sc 5242 / 2sa 1962

I am limited by space for mounting transistors , so replacement cannot be larger than the originals.
Will change all output transistors

Hello All,

My first post in this (or a) forum 🙂...

I'm working on a circuit where I discovered that the behavior in spice simulations is quite different from what I find in reality. Of course, this is no news to most here...
But my question is, maybe I'm missing something in the LTspice settings since my results are not even close to the diagrams I'm getting with LTspice?

Attached are the screenshots and .asc file used to give the overview.

I'm hoping somebody will share some insight here,
Best regards, Rens.

SuperPlayer - The DSP_Engine (CamillaDSP) samplerate switching & ESP32 remote control

Thread title changed at member's request.

Hey all!

As i feel guilty filling Henrik's amazing CamillaDSP thread with my stuff i am opening this thread to use for this SuperPlayer i hacked and created "howto's" for.
When i did this hack, and decided to make auto sample rate switching possible for my squeezelite/camilladsp combo, i didn't throught it would be as of any interest... But i was wrong, there seem to be a lot of people out there using it, part of it or whatever, cool... I'am really glad to contribute.

Lykkedk (Jesper Lykke) * GitHub

I have three repositories, the original SuperPlayer and a SuperPlayer v2 for upgrading the SuperPlayer to newer versions of CamillaDSP.
Along with that i have a fork of squeezelite, with the hack i did in the [Master] branch

I AM NOT at all any guru into programming or Linux, but been using it on and off for many years i know my way around it a bit through 🙂

• 
  Also i am not allway's fast at reply's... so hoping everyone contribute here.

I hope this thread will be usefull, welcome!

Jesper.

Hi,

I’m thinking about making a linear power supply for my Sony VFet n-channel amp.

Wondering what approach folks have taken when making one?

Curious to see what experiences have been when adding one as far as the Amps performance changed from using a linear power supply vs using the SMPS.

Thanks!

Per

Here for sale my spare ML38 Preamp PCB set with remote PCB. This is the complete preamp, with everything you need to build a real Mark levinson ML38 preamp.
The Main PCB is original ML38 that is really the complete preamp, with dual mono power supplies, relay source selection, digital volume control (in the analog domain without loss of resolution), eveything.
At the time Mark Levinson was offering to his customers his preamp upgrades by swapping the main PCB, hence this original main PCB for the ML38.
All that was needed to have a complete preamp was the front panel PCB, volume rotary encoder and a remote.

At the time I made numerous kit to complete the preamp, and I kept two spares.
It is your chance to get a full function, top of the line real Mark levinson ML38 preamp, for a fraction of the price. This is a real commercial, high end SE/Balanced preamp, not some DIY flinky one opamp preamp...
You can simply mount it onto a piece of wood, and you'll have the real preamp, without any extra spending, or make your own enclosure with the nice real panel custom silkscreen panel.

This preamp is currently configured for 120Vac, but by changing a few jumpers can be easily configured from 100V to 240V.

The kit comes with full schematics and instructions on how to change the AC configuration for AC worldwide compatibility.

At this price, it doesn't even cover the cost of the high parts used on this board, custom plitron power transformer, real high quality Agilent rotary encoder, custom ML RCA connector, etc...

The complete kit includes: Main ML38 preamp pcb, front panel pcb with flat ribbon cable to main pcb, Volume original Agilent rotary encoder with cable, remote pcb with battery adapter, remote custom top plate with silkscreen and button, rear panel silkscreen panel, AC input inlet and even the little DACD38 original pcb that allow for ML control link, IR repeater, etc... The main PCB firmware was also updated to the latest ML380 firmware, so it has the ML380 latest software upgrade such as improve volume control, time out turn off, etc...

The kit will be ship into the original ML shipping box.

Complete kit had been tested and fully functional. This is a real ML38 preamp, so the original User Manual is valid. Check the web for further details.

At the asking price I'll include a few extra such as the custom discrete regulator pcb if you want to upgrade the supply rectifier to the same one used into the ML380S.

Complete kit 750U$, Worldwide Shipping accepted and will be paid by the buyer, Paypal 3.5% extra.

Let me know if interested.
SB

My Accuphase E303 show oscillation on both channels.
I recapped both output boards but the oscillation hasn’t changed.
When I disconnect the power to the output transistors the gate signals are fine.
The oscillation occurs when I apply voltage to the output Mosfets.
I have checked the biasing current which is ok,
I have tested the 4x mosfets with the simple tester (without load) and the measure OK.
I suspected the 4x 47pF mica caps but I de soldered one and it was spot on.
Could it be that the mosfets got old and cause these phenomena ?

Needless to say they are obsolete and I haven’t been able to find a suitable replacement
but perhaps it would be more sensible to maintain those original Fets
and do something about the oscillation.

I would love to see if anyone has some advice on this issue.
Many best wishes from Singapore
Bjoern