Hi all,

I'm looking for a pair of 300b SE transformers - anyone got a set that they are looking to move on? Europe preferably just for shipping reasons.

What is the color scheme for connecting Markaudio 10 drivers?

I'm current using an APT Holman preamp, which I like. But it's the time of the year to do some window shopping. Budget is under $1000, much less like $500 is more reasonable.

I may end up keeping the Apt and doing some mods to it, please dont be offernded if i dont actually purchase anything - your thoughts on a replacement are appreciated.

DIY, used OK of course. But if DIY, I'd need to be able to purchase a good looking chassis since my mechanical skills are near zero.

Nice to have but NOT necesary:
Tubes - never really had a tube amp, wouldn't mind trying
Remote volume
quality phono stage
tape loops
many inputs (I only need maybe 3, depends if it has built in phono)

Hii im reparing deafbounce aab 4900.1 amplifier i have repaired it's ps and output section but clipping light is fully on with blue light i have checked all output Ic's pwn ic, driving ics with its buffer ics all are ok. Can someone help me please

Why do designers of crossovers ignore this? OK, I can understand it's a crossover.
But then builders using these on real world boxes need an extra stage to compensate for this. Why do they choose to ignore this after they have gone to the trouble of multi-amps?

Who offers a ready built PCB that can add this?

Condition:
Open box
“New, never used.”
One pair Lowther DX3 full range drivers.

New in box, one has been opened, never used.

Accept PayPal only

$10 insured shipping
PRICE TOTAL FOR ITEMS AND SHIPPING:600$

NEXO GEO S1210 2-Way Passive Loudspeaker (PAIR) (church owned) CG00N92

• Very Good condition (A few small marks and light wear. No major damage.)
• Works perfectly. No functional issues.
• ested & Approved Gear – Each piece of gear is fully tested and approved by our ChurchGear techs.
• Fast Shipping – We ship within one business day and provide you with the tracking number.
• World Wide Shipping – We ship anywhere on the planet. Please contact us for a quote.
• Easy Returns – 30-day returns for any reason, no restocking fees!*
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• PRICE:1100$ free shipping

Hi All,

I’m probably a couple days away from a first listen on a new build so I thought I’d post some random photos so everyone can tell me all the things I did wrong that I can’t undo 😱

As per the title this is Troels’ SBA 16 MTM. My priority is midrange clarity so, after some discussion in the forums here and a quick double check with Troels I decided to go sealed and reduce the size a bit for ~.7 qtc with a -3db at 60ish hertz. Parts are from Jantzen (naturally).

I’m quite a poor carpenter so box building is typically one disaster after another. This build has been no different but I’m confident I’ll get to the finish line this weekend. I just have to make the crossover, glue in the back, make an access door for the crossover, and mount the drivers. They won’t be pretty unless I try my hands at veneering down the road. Frankly this project has been dragging on since Christmas so I have full tunnel vision on getting them hooked up in my living room regardless of what they look like. I’ll start uploading pictures in my next post.


Brian

Would it be acceptable to drive a Baxandall passive/active tone stack via a 6DJ8? I have mostly finalized a headphone amp design that is driving 6GC5 SE pentodes via a 6DJ8 (1/2) per channel, and have enough physical space and current headroom on the PSU to add another tube to the design. I've got several other 6DJ8's and Soviet 6N23P's on hand, and would like to use one to drive a tone stack in-between the preamp and power amp section, if that would be an appropriate tube to use for that. I've mainly seen high mu triodes like the 12AX7 used in that role, however. B+ here is 240v. It makes more than enough gain as is, but I'd like to keep that headroom in case I want to turn the volume up on particularly quiet tracks. Worth doing or would I be better suited to use a high mu triode?

Hi !
I apologize right away if this topic has already been debated ad nauseam
But in the world of audio reviews I see that measurements have less and less space than subjective listening
Not only that ... the few who try to find a correlation between laboratory measurements and performance are rather mistreated and the comments are even mocking
Instead, I was struck, in a positive way, by this statement that can be found in this review
https://www.stereophile.com/floorloudspeakers/99dun4/index.html
"DAL firmly believes that a full set of credible measurements, made by qualified engineering staff using state-of-the-art equipment and facilities, can reliably predict the potential of a loudspeaker to accurately reproduce the complex sounds of music."—Dunlavy Audio labs
It is known that immediately afterwards the journalist adds a lot to create some doubt and confusion
"Yet it must be said that, no matter how good the theory, how impeccable the designer's credentials, and how impressive the measurements, a speaker may still disappoint in subjective terms. The proof, as always, is in the listening"
Another interesting interview here https://www.stereophile.com/interviews/163
"John Dunlavy: Oh, no. Listening comes later. Because if you stop to think about it, no loudspeaker can sound more accurate than it measures. It may sound worse, or it may sound sweeter, prettier, but if we're talking about absolute accuracy—the ability of the speaker to reproduce as perfectly as possible whatever's fed to it—such a system can never sound more accurate than it first measures. So we try to get the greatest accuracy we can achieve from measurements. Then we begin doing what some people might call "voicing," because the best set of measurements are still open to interpretation."
I tend to believe to Mr Dunlavy
And you ?
Kind regards, gino

Looking for a couple of IMS boads for lu1014 mounting. If they have the jfets even better.

Thank you.

i live in a ural area and have limited cell coverage i have tried a couple of ideas on youtube but no help i am considering trying another one but would like to get some feed back and a better design mybe i dont have much money so i am trying to use materials i have a home one question is they use a steel clothes hanger i have a bunch of copper ground wire why not use copper for the antenna

Hey, I know there are some threads about noise problems here but I couldn't find the right answer.
I am building an amp out of an Fosi Audio ZK-502T Bluetooth 5.0 Amplifier Board (TPA3116D2 Chip).

...and I have some Issues with noise. Please hear this video for demonstration.
Login to view embedded media
For some context:
The 1 khz Sinus sound you hear is on purpose, I needed some input signal because otherwise there is a noise gate turning on. So ignore this one.
First there is this white noise like sound in the background, might be normal is not that wild. Only audible at very high volume.
But then there is also this incredible loud buzzing sound. When I touch somewhere on the circuit (ground) it gets way more silent and when I come near the cables it gets louder, even before touching.

I am connected over bluetooth, so no input device is connected.

This is the board.


I modified it a bit to build it into my casing.



I desoldered all 3 potentiometers.
The volume poti also works as an on/off switch, so I bridged these two paths to have it always on. (Red small wire)
The other connectors I wired back to the potis to have them somewhere else in the case.

Before I desoldered the potis I think there was no problem of this sort. Only tested it shortly once before so not 100% sure. My guess would be some problem with the cables or the ON/OFF shorting.

Can you please help me figure out where my problem is?
Thank you!

Hello Everyone

I got a Harman Kardon Schematic from an online source which is of a 240 - 9240 Mosfet Based amplifier.

When I tried to create a board out of it, I faced a few problems. Initially it wasn't powering/switching and I found I chose the wrong preset of 1k. I changed to same per schema, now it is giving 51 volt AC output.u

Can you please look at the schematic and let me know what's wrong with it? Also, what could be the best corrections/modifications required in this schematic so that it can operate smoothly with good results?

Thanks in advance.

Hi.

I received a pair of these speakers at a belated birthday present over the weekend. My friend thought it would be an interesting project for making some improvements on.

Unfortunately, my web searches didn't produce much useful information. One post on the World Designs forum mention a simple crossover of a 3.3uF capacitor and a 2R7 resistor. On opening the back of my units, I have 3.7uF of capacitance and a 15R resistor (plus an, as yet, unidentified component buried in hot glue).

My first change is to replace the internal wiring which is pitifully thin. It seems an odd choice, given that they spent some extra pennies on film caps instead of electrolytics.

Does anyone have any information regarding this speaker please? An owner's manual perhaps?

How about a collection of hacks and rules of thumb for audio.
It could be a simple chart showing you what range of volume your sealed speaker should use based on speaker size. You can do the complex math. And they just for fun see if the size you came up with matches the rule of thumb chart.
It could be a hack to help you pick the best transistor from a pile of possible transistors you could use for a project.
My guru says there is nothing as perfect every ear has its own preference. So why not pick a transistor my ear likes.

Let me get the ball rolling with my idea. (It could be a brain fart). So humor me.

The number one problem today with all parts is fake or substandard parts. Or picking the right part.

So I have this pile of transistors and we need to find the one type which will sound best.
Was looking at some videos on youtube where they explain how to build an amp with one transistor. A cap and a resistor.
What if I were to build a bread board where a single transistor is replaced one after the other. Power supply used is based on where in the amp the transistor is being used.
And I play some test tunes. or music and then swap out the transistors one by one. And just listen to the music. I could also use a spectrum analyser on my phone to get an idea of freq response off each transistor.
Do you think the idea has merit or do you have a better idea to quickly pick from a pile of similar transistors. The test rig could work with a single transistor or you could make one which works with PNP / NPN pairs. Im not chasing perfection just a quick and dirty test rig. Instead of a speaker we could use an audio jack and feed the signal to a scope or the mic in of your laptop. Also if its a fake it pops on the board. Worst case taking out a resistor or cap vs taking out a complete board and many other components with it.
Im still trying to understand how to pick the best transistor from a pile. With my component tester i.e. is HFE important as in higher HFE= Better. Or a certain pf value or its speed from the datasheet.

I recently purchased a used, nice condition Musical Fidelity A308 integrated amp. It works well and sounds great. I opened the top and I did notice what looks like significant modifications of the original factory capacitors throughout the unit. Below are hi res photos. Note the banks of caps sitting on wood blocks on top of the power transformers... and there seems to be replaced silver colored caps all over the main circuit board as well. The caps are not marked with branding, also no values can be seen. Below the pics of my unit are a link to an old for sale ad of a stock unit... the pics in it are not great but one can see the black original caps...

I am curious to know, if knowledgeable people here can tell me, what these modded caps are and any other thoughts or comments you might have. I will repeat, the amp is dead quiet and sounds great.

And FWIW - here is the link to photos of the innards of what should be a stock unit:

https://www.hifi4sale.net/t73965-musical-fidelity-a308-integrated-amplifiersold

I am building the Akitika Z4 Power Amplifier kit.
It is based on LM3886 - I hope they will be in stock again.
The kit has been sitting for 6 months due to work, but now I started. I think I am somewhat 60% done.
You can read about the kit here - it comes with everything except solder 🙂
I am building the 4 ohm version. It is actually easier than I thought.

There are 3 major modules, the Power Supply Board, and tho Amplifier Boards. Here a quick status.

The manual quite clearly writes how to get started, and what bags to find stuff in.
I never thought I should write it - but the PCB is quite nice. Thick and solid.


It does seem a bit scary , but it is not that bad.... I even cannot really solder. But I found the key trick is to heat up pin a few seconds before adding solder.




Within a few hours I actually made progress.....



The board is soldered on the back....




Done.....
Next, Amp board.....



Image below of finished Amp board and power supply board. I just need to finish one more.
And install it all with power supply, and a bit more stuff.



Here it will all go....



More is coming... happy for any suggestions or questions..

I'm working on a LM3886 amplifier, and I have it working and it sounds mostly great. But when I put my ears up against the speaker, I can hear a little bit of what sounds like faint power supply noise.

I've been messing with the grounding, but I can't seem to nail it.

Right now for testing I have two RCA inputs that are isolated from the chassis (verified with a multimeter). These go to two different PCBs representing the right and left channel. These are connected by two 2-wire twisted pairs. If I don't tie these to ground within the amplifier, it doesn't sound good at all. If I tie them to ground at the power supply caps, it sounds good, but it has the faint hum with my ear up close (this is the current configuration). If I take one channel and ground it instead at the speaker gnd of the appropriate channel the hum goes away and it's totally quiet. If I do the same with the other channel though, the sound gets worse. The RCA cable source is my iPad using a mini audio connector cable that splits into RCA.

Another question is should the INPUT GND be totally separate from the SIGNAL GND/ I read the Taming the LM3886 article, and it seems the consensus is to tie the SIGNAL ground into the speaker negative terminal, but it doesn't really mention what happens to the INPUT GND.

Thanks.

I want to selling audio research what best price selling

where can you sell

Item: Audio Research Reference 6
Location: Georgio.Decatur
Item Condition: MINT.
Reason for selling: Not used after upgrade to audio research reference 9
Price: US$6100+ postage.
Payment Method: Paypal buyer portection
Extra Info:
Bought from a specialist dealer in April 2020. First owner.
Condition: like new. Only 1639 engine hours.
Age: 2 years 7 months.
It is not the SE version.
Including 6 tube dampers from EAT (Cooldamper) for € 180.00.
Including 3 fine fuses Supreme 3 from Hifi-Tuning for € 135,-.
For a surcharge with LEVAR Resonance Magnetic Absorber Leveling Feet LR7-HA (SP € 899,- for € 650,-.
New price Ref 6: € 17,900.00. The Ref 6 SE even costs €20,900.
Invoice, original packaging, all accessories available.
No replacement.

Test results :

"The Reference 6 high-level preamp is a monument of current tube technology and an enrichment of the top class. It impresses with crystal-clear, spacious and highly dynamic sound performance, which, paired with excellent precision, leaves nothing to be desired. With its typical design, it proudly shows its origins , the workmanship is flawless, as you would expect from Audio Research."

" Somehow Audio Research manages to outdo itself on every occasion – at least in the last few generations of Reference series preamplifiers. The Reference 5 SE was among the very best preamps on the market, yet the Reference 6 takes it to another level.

To qualify this, the Ref 6 is substantially more transparent than its predecessor – you really hear into the recording (as an enthusiast and reader of these pages, I'm sure you know what I mean) – and thoroughly overshadows it when it comes to macro-dynamic expression and bass power and control.

By having the Audio Research Reference 6 preamplifier within the context of your system you'll feel well confident that it will never be the bottleneck inhibiting your stereo's full musical expression.

These speakers are heavy, and are minimally packaged.

-Kit of parts https://www.diysoundgroup.com/tempest-12.html
-Flat pack cabinet kit https://web.archive.org/web/2015031...speaker-kits/fusion-12/tempest-flat-pack.html
-Other necessaries purchased: glue, lining, binding posts, paint, boxes for (external) crossovers.

You can see from the response curve shown on the Fusion 12 page that there is a rising low frequency response. This makes the speakers sound as if the response goes lower than it actually does, but this rise also makes it difficult to integrate a powered sub. I put together 6 fabric covered styrofoam balls to experiment with raising the F3 of the speakers. I found that 2 worked best for me. The purchaser of the speakers gets the 6 plugs, and also a schematic of the crossover.

Finish is black Duratex. Lining is 1” thick adhesive backed acoustical foam. Two sets of binding posts on back of cabinet, one set to each driver. Crossover capacitors upgraded to SoniCap Gen 1, and Cornell Dubilier bypass capacitors added across each.

Subs shown NLA.

When simulating a center-tap full-wave rectifier circuit, the transformer current is high by a factor of 1.414 (should be same as diode current) and waveform shows positive and negative pulses (should be positive only). Both occur only with latest version. And the table formatting is awful - need to resize every column each time I use it.

I've been using version 2.0.04 and will continue to... it works fine in Win10. I'd tell the author if I could find a contact.

Hello,

I'm slowly introducing myself to the world of diy audio and so far it's been great ... untill i met the dynaco 120 🙂
After an easy repair (2 transistors and a capacitor) it played really good for a while.
Then one day it blew up 🙂
After trying to repair it like i did last time, it failed again with more smoke ...
I decided to change all the electronics on one channel and still nothing 🙁

I am using MJ802 as replacement for 2N3772 as that part is not available here.
In fact the amp used to work with MJ802 for a while so I guess they should do the job.

The power supply gives a steady 71.6V when the B+ of both channels are disconnected.
When I connect the right channel I get 71.6V across both collectors of Q5 and Q6. I know that 1 should be 71.6 and the other around 36V ... half the supply voltage.

With the left channel connected, the supply outputs around 10V and readings on the pins of the PCB get really weird -72 and such.

Hope someone can shed some light on whats going on.

Thanks for your help,

Ilan

Hello,

I wanted to start this thread to discuss the Heathkit AA-1800 Stereo Power Amplifier.

So, I guess my first question would be:

Does anyone know what the voltage ratings are for the power transformer? I can not find it in my manuals nor is it located on the unit itself.

I was considering perhaps making separate power supplies for each channel and locating the supplies in a separate chasis.

My Capacitors need to be replaced as they are original and I am sure are out of tolerances. So, I figured I would considerably increase the uF values ( ie, larger and/or more caps). That got me to thinking about separate supplies, basically for a project to do.

I am sure I would have to have a transformer made if I where to go with the same size. So, I was considering a new pair of toroids??? I would hate to gut a working amplifier to get a transformer from it. I own 3 now and just don't have the heart!

Recommendations/Suggestions?

Thanks!

Ed

The kit was bid from Japan, labelled that it was made by 1986, imaged with Pioneer AU-999. I think it is a pre-amplifier, but cannot get a circuit diagram from the internet websites. As enclosed with the pictures for searching the circuit diagram if having. Thanks a lot.

Having trouble selling you're conflagulator box? You're simply marketing in the wrong place!

At "ShopGoodwill", you dont even have to say what the box does, or what any of the controls do, nor mention those pesky power requirements - and folks will open their wallets wide for you!



Not that the commercial stuff goes any cheaper;



I watch this stuff for my own amusement. Volume, bass treble gain. I think you can do that. It's just a matter of where you market your creation! Stomp boxes are alive and well. Now, where's that log-amp schematic?

Greetings All!

I just finished a recap on this very nice vintage receiver and all appears to work well except...

I get a sizable pop out of the speakers when the protection relay kicks in and when it clicks off. The volume pot has no affect.

The recap was done to the entire amp board and anywhere I could reach that didn't require the chassis to be disassembled. The filter caps were left alone and the power supply board has no other caps. The amplifier coupling caps were replaced with Wimas.

Like I said, other than the pop on/off everything else appears normal. DC offset is reasonable ~ 20mv. I can provide images of the manual if you like.

I did run this inquiry by the folks at AK but didn't get a solution.

Best Regards,
Mike

Even if a similar question specifically applied to a phono preamp, I think the question on how to better star ground a schematic when you design the pcb is a much larger issue.
On analog audio it applies to all types of circuits, be it low noise or not. Power amplifiers are certainly not low noise designs, but you have be careful with the input stage, where signals are more susceptible to different type of interference.
Star grounding is relatively new concept, which was very talked about and discussed in the late '80s and '90s, probably when DIY became more demanding and sophisticated.
Perhaps people can come to this thread and tell about what worked for them, and how it was implemented to cure hum and RFI, which became a problem when cell phones got popular. Local decoupling became almost an art, complementing star grounding when it existed or solving the noise problem when it did not.
I will google about this matter and look here in DIYAudio a bit too.
Let's hope people get interested.

I picked up a M&K MX350THX subwoofer super cheap recently.

The cones moved a little but virtually no volume. I visually checked the main logic board and didn't see anything obvious. I then the power supply. One cap had brown stuff coming out of the top so I ordered 4 new caps of the same manufacturer and specs. Could this bad cause almost no volume?

Finished assembling the amp, LEDs light up both channel, I was able to set the DC balance, but extremely low output from the right. My knowledge of electronics is very limited, this is the 3rd amp kit ( Hafler and Akitika) I have built and the others work fine. I checked the back side of the board and can`t find any cold joints or solder bridges. If anyone has time to look at the pics and advise me, I would be grateful. I`m hoping it is something simple. Thanks.

Hi,
I'm building a class a amplifier similar to the design in this wesite:
https://sound-au.com/tcaas/jlhupdate.htm

This is my first class a build, and I have never do biasing before. I've searched online on how to bias a class a, and this is what I found:

• to set the bias voltage: no input, no load, connect the multimeter to the output and V+, using the vr set the voltage to 18v (I'm using 18v symmetrical power supply)
• to set the quiescent current: no input, no load, connect the multimeter between the (+) input voltage and power supply, using the vr to set the current to 2.8 amps as stated in the website

Please correct me if I'm wrong. I've seen some videos where they biasing with load (speakers) connected, and I don't know which one is correct

Thanks

I made some small sealed box stand mount speakers with Markaudio CHN40 drivers for my PC and they turned out great, but I'm toying with the idea of making a new box for the drivers which would improve the bass and not require stands. I have a plan for the box as file but wondered if I could reduce the height to 420mm, and if so what other changes would be required like port slot size. Thank you in advance, just feeling my way at the moment.

I have a question to those who are familiar with the Yamaha A-700 / A-1000 line.

I've been working on an A-700 on and off for a few weeks now, which was going in and out of protection. It was also not balancing correctly in tape monitor mode / only working in Mono mode. On first looks, I saw the glue had corroded a bunch of resistors and diodes around the 2 680uf caps, so my first instinct was to pull those, test them, and either replace or reinstall. I opted to replace the resistors since that's a nominal cost, and I replaced the caps as well. Left the diodes alone as they measured out fine. Once I powered it back up I had no power to the LED boards on the front panel. Screwed around with it for a while, back-tracing my work, and could not find anything obvious. Then I started seeing all the dry solder joints and literally moving transistors. So I went through the board, re-soldered all the transistors that felt wiggly and also some just because, might as well. I now have power to the front panel, but still no relay. I am getting voltage at the hot side of the relay (51V -on the dim bulb) but something is preventing the relay from engaging.

I have attached the section of the schematic I am concentrating on, which revolves around the relay itself. I am getting 51-52v at the collectors of TR151 and TR152, but I'm not getting the supposed 4.4v at the base of TR151. TR150 I get nothing, and I wouldn't expect to. Logic would tell me the transistor is bad or the solder joint is bad, but I removed and tested the transistors (all 3) on my Peak meter and they all check out with no shorts.

If anyone has any insight on this, please let me know. I am getting B+ voltages at other parts of the board where noted, so there shouldn't be any issue with the supply.

Good evening folks,

I received a kit to mod my Fender Blues Deluxe Reissue Guitar Amp and what I was supposed to receive and what I received are different primarily for the tone stack and volume and drive pots.

I'll list what I think I should have received based on the ad and what I received, for those that mod tell me what you think of the substitutions:

C5 - .1 Orange Drop (received .1 Wima MKS 4)
C6 - .015 Orange Drop (received .015 Wima MKS 4)
C7 - 250 Silver Mica (received 270 MLCC)
Across pins 1 and 2 of the volume and drive pots 100 Silver Micas (received 100 MLCCs)

Your thoughts?

Hi,
somebody can tell me if this meter work with this build?

https://www.gyraf.dk/gy_pd/1176/1176.htm

Description:
Panel-VU-Meter with Frame
Part-Nr. : SD-740 -B
Dual-dB: -20~+3dB
with 12V Color=Amber Bulb lamp
with black plastic mounting frame
DC 500uA Full Scale, DCR=650Ω
(Item is only for a display meter, design the driver board by yourself, not included, please understand)
Thanks!

I once came across an excellent site for classic audiophile equipment. It's a generic site that looks really old, with a beige background, but excellent content. It even has audiophile music files for free download (all legal). Anyone know the URL for such a site?

Thanks for the help.

The Markaudio 7MS has a resonance and a corresponding dip in the response at 460 Hz.

Then I had this idea that I might be able to fill that dip with a cleverly tuned port with its port resonance at the same frequency...

Is filling in a resonance with another resonance a really bad idea or a clever one?

Hello everybody and Merry Christmas

I have had this project in the works for about 6 months but really haven't had much to show so I waited until now to really post anything. I am both envious and intimidated with the amount of knowledge people on this forum have, most of you have forgotten more than I will ever know.

I have a set of almost new panels from a Martin Logan Quest including power supplies that I purchased from a user on the Martin Logan forums. I am going to build a hybrid ESL using the panels, custom stands and woofer enclosures.

I chose to use Fane Sovereign Pro 12" woofers for bass support. These have good response out past 500hz and have very low moving mass so integration with the panel will hopefully be pretty good.


I'm using the OEM Martin Logan power supplies with a pair of MULTICOMP PRO VTX-146-050-106 toroidal transformers wired together to get the correct winding ratio. Original transformers from Martin Logan are no longer available for this panel but other people have used these smaller toroidal transformer with good success.

The entire speaker will be ran off a Dayton 4X8 DSP unit, I will not be using any form of passive crossovers on the woofer or the panel. I will probably be crossing the ELS panel over with a 350HZ highpass @ 24BD/octave and the woofer will be bandpassed at 350hz and 60hz. The lower bass extension from 60hz and down will be handled by subwoofers. This seems to be a good starting point when looking at other hybrid electrostatic speakers.

The main construction of this speaker will be laser cut 3/16" steel, including the woofer enclosure. I am proficient in AutoCAD and routinely send large parts order out to a laser cutting company so for me this is actually an easy and cost effective option. I am not a good woodworker and my entire shop is setup for metalworking.

I plan on getting all the fabrication completed before the new year so more updates to come soon. I have included pictures of the progress so far below, I'm interested to here what everyone thinks.

I have a Rockford P600x4 with two burnt transistors (Q103,Q105) on the
P/S card 1325-57321-02. Any help identifying these components would be
greatly appreciated.

Hi:

I need to replace a broken thermistor on the Adcom GFA-555. The service manual specifies this to be TDS-C210 1K thermistor. Unfortunately, I have not been able to find its specifications, datasheet or references to substitutes.

Would it be OK to replace it with this one from EPCOS/TDK:

B57164K0102K000 EPCOS / TDK | Mouser

Thanks in advance,
Mayank

I’m trying to find a way to upgrade the speaker connectors on an old Silver/Harman Kardon amp and I had seen someone do similar with some panel mounted bullet sockets. I have tried everywhere I can think and haven’t been able to source any, so asking for ideas. Picture attached. Any other ideas would be welcomed, it currently has 2 pin DIN sockets that are a bit unreliable.

Hi all,

I want to play around with STM32 Cube IDE and embedded C for some audio projects. The goal is really just to learn a bit about embedded C, STM32, DSP and to have a bit of fun.

For example, let’s say I just want to apply at FIR to an audio signal from line-in or onboard microphone.

Any recommendations for development board would be appropriate?

Hi
Im making my first 2way speaker, i want to do as good phase as i can under other compromises.
Any feedback is appreciated, i really want to understand this..

There are "rules" like you have to change driver polarity with second order, but not really explanation why and how phase works (at least with just googling resources..) so i made this thread to see have i understood how crossover order affects phase with ideal drivers.
I have understood that for every order (1,2,3,4), highpass and lowpass moves phase out 90 degrees of original pole to different directions.
(this direction is constant as orders go higher)

This is on flat speaker baffle:
-----------------------------------------------------------------------------------------------------------------------------------------------

-P0: First image is loudspeaker signal without crossover.

-P1: First order:
LP woofer signal has moved 90 degrees left and HP tweeter signal has moved 90 degrees right.
Both drivers are 90° out of phase looking original signal and 180° out of phase between each other.

-P2: Second order:
LP woofer signal has moved 180 degrees left and HP tweeter signal has moved 180 degrees right.
Both drivers are 180° out of phase looking original signal and again in phase between each other.

-P3: Third order:
LP woofer signal has moved 270 degrees left and HP tweeter signal has moved 270 degrees right.
Both drivers are 270° out of phase looking original signal and 180° out of phase between each other.

-P4: Fourth order:
LP woofer signal has moved 360 degrees left and HP tweeter signal has moved 360 degrees right. They are back in phase, but one cycle out of order.
Both drivers are 0° out of phase looking original signal and again in phase between each other.

Anyone noticing how discrete parts prices are rocketing upwards... feels like just yesterday (well 2007) that the MJ21193/4/5/6 could be had for less than $2 a piece. Now on Mouser etc they are over $10 Each !!! Even the reasonably priced MJL1302 are over $5 now... this is making the hobby a lot more expensive for larger builds...

I just finished measuring a completed speaker, and am somewhat surprised to see that the measured response of the crossover is quite different from the modelled response. This is the crossover:


And here is the response:

(I know the response isn't pretty either way, but that's besides the point right now.)

The orange line represents the measured response of the complete speaker, the blue line is the modelled one using raw driver measurements (all gated farfield measurements with a 4.5ms window). Up to around 2.5kHz the lines are quite similar, but in the higher frequencies not so much. I am 100% positive I did not make a mistake in the crossover assembly. Measuring equipment was a Behringer UMC-22 audio interface (with loopback for reference in REW), a Dayton EMM-6 mic, and a cheap TDA7498E amp from aliexpress.

What am I doing wrong here?

I have attached the FRD and ZMA and VituixCad files.

Hi All,
I'm building a living room spk, 1cuft, vented and am considering the Pluvia or Betsy K? I think the posted response for the Betsy K is smoothed? I like MK ( I have 10p in my main system) and would jump on the Pluvia if it was not a metal cone. I never been able to get past what metal cones do to string instruments ( especially cello). So looking for recommendations. Anyone have a real Betsy K response graph? Any other "cheap" driver I should consider. Had Fostex FE167e at one time...liked them but no longer made (maybe FE166nv).

In the end this is what I built ... transients tested and listening tests ... it sounds fine (soon I will post a small video of the horrific creature). I hope I didn't make any mistakes in transcribing it to TinyCad.
Write me if you have any questions, suggestions or complaints ...

(WRONG SCHEMATICS!)
(the right schematics at #3)

I have a Roberts preamp & 2 Stromberg Carlson APH 1100's that I would like to modify into a hi-fi that would work with a turntable/tuner/CD player. All separate components. Would this be worth the effort? Any advice would be greatly appreciated. I recapped the 1100's a few years ago but the preamp could probably use it.

Hi,

Not sure if this the right place.

My Creative aurvana play 2 headband is broken, and I thinking to replace the housing to this: https://www.aliexpress.com/item/1005004041053880.html?spm=a2g0o.cart.0.0.3aae38davtoGEJ&mp=1

Any suggestion on what I should be aware of?

Regards.

UPDATE 11-9-2022: Critical update to the project in the post #18. Major layout error involving LM337 was fixed!
Update 12-24-22: Project was revisited and redesigned from the scratch.

The idea was to make a single board that will include it all:

• two channels of inverted LM3886 amps
• input buffer OPAMP
• rectifier bridge
• filter caps
• power delivery for the OPAMP

To finish the project you would need:

• case
• heatsink
• transformer
• RCA inputs, binding posts outputs
• power plug (preferrably with EMI filtering)

Board size is 200mm x 75mm.

Input level for this amp is set to +4 dBu - typically found in professional audio equipment.

Input buffer OPAMP can be NE5532, LM4562, or any other.

Attached are schematics, PCB design, simulation file, and gerber files.

Had a idea that it should be possible to do an MEH with a co-axial woofer.
Sort of a cross between a Tannoy co-axial and an MEH.
The horn portion of the MEH would pass thru the woofer, and the woofer would be connected to the horn via short holes/slots, rather than use the woofer cone as the horn, as the Tannoy does.
This should make it possible to make the interface between the woofer and the horn into a proper phase assembly, just like a scaled-up compression driver.
Better phase coherence should provide a lot more flexibility.
Obviously this requires a woofer with a hole thru the centre, MacCauly do one, for their own modular coaxial speakers.
Anyone tried this?
Or have any recommendations for woofers?

David

Hello Forum,
I am new here - been a professional engineers in research (audio compression), with an amplifier manufacturer (R&D in digital and analog Audio) and the last 20 years in the digital communications industry.

I have grown tired of my high end system with narrow baffle, high resolution sound. Now gradually building up a system that it fun to listen to (I have two Audio Research D150 under restoration) and some big JBL studio monitors - actually making a system from the period in audio when I thought listening to music was fun and gave a you a feeling of being subjected to something which touched you emotionally.

In connection with restoring the D-150's (I do that absolutely without compromise - respecting also the period of the equipment), I have noticed that the magazine "The Audio Amateur" has a sort of review of the D-150 in issue 2 1984 (Classical schematics). I do not have this article (naturally I have the schematics and the parts-list), but I wonder if some additional text goes together with this in the magazine.

Is there someone out there whom could be willing to depart with this issue - or just a copy of the article? I would be a very happy receiver/purchaser.

Thank you and best regards

Morten

P.S. If anyone is busy with a D-150, I have found an error in the construction which is present on both of my amplifiers (the high impedance feedback from the primary of the output transformer back to the drive V9 (&V10) is connected in in-correct phase for the right channel - thereby introducing a slight positive feedback instead of the negative feedback as intended by the design)

Here's how you can do loudspeaker simulations in the Cloud.











Above are the five steps I used to create my instance in AWS. You could do this in Azure or GCP also. I've heard GCP is generally cheaper but I know AWS the best so that's what I used. (Patrick Bateman AWS Certified Solutions Architect)

I'm using this instance for my ATH ABEC sims, because the latest version that can do enclosures really needs some firepower. I'm using an AMD Epyc

Here are the specs and pricing:

• Instance name On-Demand hourly rate vCPU Memory Storage Network performance
• m6a.4xlarge $1.4272 16 64 GiB EBS Only Up to 12500 Megabit

This PSU I use for SS Preamp. Output voltage +/-24Vmax.

Does anyone know how to build a balanced inverse RIAA network or are threre any papers available?
I didnt find anything so far....
Thanks!

I have been working on scripts to speed up development of midrange horns in AKABAK3. They are in an early stage of development but I have decided to share them as they might be useful to people. At the moment they can generate meshes for horns based on horizontal and vertical guiding curves. This means that you can create scripts to draw any rectangular horn. Everything is very crude atm!
https://github.com/kipman725/OCTAVE_HORNS

The reason for this is that I am trying to make a horn for the M200 compresion driver with the following specification:
90x60 dispersion (-6dB)
400Hz - 4kHz operating band
maximum 0.9x0.5m mouth size
'good' loading, I'm not quite sure what would be acceptable but it seems a normalised real part of throat impedance of 0.2 is posible at 300Hz

Attached is some data on various exponential flare sections joined to a 90x60 conic-conic horn simlar to the EV HP640:

Edit - Jan 12, 2014: The bottom line - here is the final in room response and THD of the Nautaloss II Reference Monitor with Subwoofer and DSP crossover. -3 dB points are 42 Hz to 18 kHz, THD is between -30 dB to -40 dB at an average of 96 dB SPL at the listening position:





I started this speaker in the Foam Core thread (http://www.diyaudio.com/forums/full-range/223313-foam-core-board-speaker-enclosures-203.html#post3734447) on somewhat of a whim as I was inspired by the namesake speaker and wanted to try a quick and cheap foam core version to see what it may possibly sound like. (Anthonybisset is credited for coining the name)

Usually, I model and simulate a speaker pretty thoroughly before a build, but in this case, the concept was to have a spiral sealed-TL so I thought it would not be as critical as the point was to absorb the back wave and provide bass extension to as close as possible the natural fs of the driver in an open baffle. Eschewing sims, I began directly with a pencil sketch on a piece of foam core and drew an approximate 36 in long spiral that fit in a 12 in tall x 9 in deep envelope (to keep a reasonable size for a bookshelf or desktop speaker).

I then added some internal bracing at 90 deg intervals for the first 360 deg.

Then put in some speaker wire and added pillow stuffing. I glued some open cell foam around the flat areas near the front - the idea being to avoid any flat surface that could produce a back reflection or resonance that might show up on the front side of the cone. I then capped it off with a combination of hot melt and pva glue. Let it dry for 6 hours then installed the Vifa TC9FD driver.

First sound listening impressions: wow! - the clarity, transparency, and overall balance was just amazing. Although it has no bass below 150 Hz really given that the fs is 120 Hz, however this is perfect for use with a helper woofer or subwoofer crossed at about 200 to 300 Hz. The speaker really sounds good.

To confirm my suspicions that the speaker was indeed very even in character, I set out to measure it using a Panasonic WM61A mic capsule wired to my laptop soundcard. This works well below 5kHz but unfortunately cannot get anything above 6kHz due to what appears to be a low-pass filter built in to the mic input as it was designed for web chats.

The initial measurements really shocked me by how flat it was from 300 Hz on up. The measured THD was very low - I would say probably rivaling some of the very best full range drivers out there costing many times more. However, there was this pesky drop off in the response that made a cliff at 300 Hz. After scratching my head and looking at some sims in Akabak, this drop is a room-effect (distance to walls and floor).



Here are sims without room reflections:


Here is the sim including rear wall at 50 inches and floor at 45 inches high:



I then repeated the measurement with the same driver in an open baffle at the same location and also saw the same 300 Hz cliff, confirming that it is not the speaker enclosure (nor driver break-in) that caused this effect. The next step was to orient the speaker so that the room walls were 45 deg and I added a sheet of open cell foam and a pillow on the floor below.



The new measurements with the room effects, now mitigated, produced a very nice frequency response curve from 150 Hz on up (I will assume that above 6 kHz the speaker performs closely along the manufacturer's published data - which is actually very flat for a full range driver). Note that from 200 Hz on up the variation in SPL is only about +/ 2 dB and the THD is typically below -50dB with a wide loaf shaped bump at about 3kHz but still very respectable. The phase variation over this range is also very linear and relatively flat. I believe, all these things point to a speaker that will sound very coherent and accurate. Finally, looking at the impulse response function, we see that this speaker has an almost ideal response function that is very clean and short with minimal ringing. This might be described as tight, clean, or fast.

Given that this speaker appears to measure very closely to an OB, I would say that the spiral is doing its job of acting like an infinite cavity by absorbing all the back wave without any reflections.

This speaker can be constructed from exactly 1 sheet of $1 foam core stock and the Vifa driver costs $10. These are not the most efficient drivers but at 85 dB for 2.83V input, they are not bad for near field use. The frequency response flatness, the low THD, the linear phase variations, and the near ideal impulse response make them perhaps one of the best values for a near field "monitor" from 200 Hz to 20 kHz.

Finally, here is the measured response with the effect of the room wall/floor bounce cancellation effect mitigated:



It is a fun and easy quick build. Give it a try if you are looking for a cheap but accurate speaker. This will make an excellent top for FAST system.

Cheers,
Xrk971


*** Edit (Jan 5, 2014) *** added measurements from dual driver Nautaloss II (including waterfall and spectrogram).

Nautaloss II Measurements are here: http://www.diyaudio.com/forums/full-range/247598-nautaloss-ref-monitor-11.html#post3766222




Here is the pdf plan for the Nautaloss II http://www.diyaudio.com/forums/full-range/247598-nautaloss-ref-monitor-19.html#post3788028


Freq Response is very flat from 200 hz to 18 kHz:



THD is -50dB!:



Spectral Decay:

Hi guys n girls newbie here looking for some pointers on a 300b build,the most suitable output and power transformers to use.any help most appreciated.

I'm selling a pair of speakers I built. Each speaker uses:

• 2 x RS225 reference woofers in a mass loaded transmission line (MLTL) design by Paul Kittinger
• BG Neo10 midrange on 1" thick solid bamboo open baffle with optional bamboo rear cabinet (included)
• BG Neo3PDR tweeter with shallow wave guide trim and optional back cup (included)

I am running these tri-amped with an active crossover (not included). There are protective caps on the mid and tweeter that are well out of the operating range of the drivers and are just there to protect against DC or low frequency signals. Otherwise there is no crossover.

The woofer cabinets are very solid, ready veneer or painting. The mid/tweet portion needs final assembly. I just don't have the time to do this.

Available to audition in San Diego. Local sale is preferred.

$700/pair

I decided to run a separate topic on S200 so not mixup with other Stasis models and no outdoor activities…

I am a big fan of Nelson amps, always had great time with my 150.5, Fet 10e, S150 mk I, s300 mk II, but I always wanted to listen SA and S optical bias, finally catch S200 optical bias S/N: 04504 (what is the year of manufacturing btw?).

The amp came in so-so condition, so it was fixed, tested, measured (dc offset: right ch 13mV / left ch 107mV), disassembled, cleaned (no bad soldering points found), measured, trim pot replaced, pictured, assembled, adjusted based on the recommendations from DIYAUDIO, thanks to Mr. Pass, Zen Mod, and other beautiful and kind people from this forum.
Here I share some pics and hints I used...

I was surprised to see 2K trim pots on s200 driver boards, and I did not have them at home, so replaced them with 5K Spectrol multiturn, works fine!
Unfortunately, I did not have 0.15 uF film (only 0.1uF) to replace 0.15 uF 35V tantalum (I guess they are optocupler shunt caps) so I left them on until I will be able to shop them.

Caps are original grey 15000 uF 75V MEPCO.

I also found that all 1Ohm 2W WW resistors have a bad tolerance from 0.88 up to 1.07 Ohm.

I was surprised to found that 3 Ohm 2W emitter resistors are Carbon Composition… Do I need to replace them with nice Dali WW?

All output transistors are original 15004 (PNP) and 15003 (NPN), 1988 and 1989 year of manufacturing, the rest are: 2N5566, MPSU10, MPSU60, MPSA42, MPSA92, but also a one I never seen in Stasis before – PN4250A (see the pics), but the soldering points looks like original…

I wash the driver boards with toothbrush and flux cleaning, so they looks nice now.

To avoid occasional shorts (heh I had a bad experience before) I solder thin temporary wires across the middle emitter resistor on the positive rail, so it was very convenient to measure the voltage drop and to fine tune, thanks to the multiturn trim tops. Use a pare file as a top cover.

Finally I ended up with 51.1 degree on both sides, with voltage drop of 95,75mV vs 95.5mV per channel after 2H, and it works quite stable, I would say it perfectly tuned. Maybe a bit hot…

DC offset now lowered down to 97mV. Still need advice were to dig to fix.

Also I need an advice on MDA3502 bridge rectifier, which I want to replace with 16A 600V DIY based on HFA08S (which sound signature I like), but I am not sure if this one will have enough current on startup, would appreciate your opinions.

I just want to say, I am in love with this baby, it is far ahead of s150, as I can remember..., so far very positive about optical bias sound signature!

Hi I'm new to this froum a greeting to all .... I have a problem with my MC 275 I think it is the SS version (serial number E10381), in particular one of the two NTCs on the primary of the power transformer T1 has blown and in phase a loud metallic hum is heard when listening. I replaced the NTC with one with the same code (CL 70). Now the mechanical hum has subsided but there is a loud noise on the speakers and when listening it feels distorted .... Can anyone tell me what to check and where to download the wiring diagram for this model? (I find schematics of other versions but not of this one). Thanks in advance...

So I have a solid state DAC, Preamp, and Power Amp. I am adding a tube buffer (Musical Fidelity X-10D) (2x 6922EH) for some of that valve “magic”. I have it attached to the preamp tape loop. It sounds great but occasionally there is distortion. I suspect the DAC’s output is over driving the tube buffer stage. The distortion is not present when I do not engage the tube buffer (turn off Tape Monitor). I will mention, all connections are RCA single ended. I know the DAC output is “hot” at 2.127V. When I drop the DAC output (has digital “preamp” volume control) 4-6db the distortion seems to go away.

My questions (go easy on me, I’m totally new to tubes). Is the line level output voltages to high for the tube buffer input? It was advertised to be used between a CD player and a preamp. Is the DAC output too high with hot recordings? What is the preferred connection to support all my inputs (digital and MC phono)? Should I skip the Tape Loop/Monitor set up and instead place it between the preamp and the power amp? With this configuration, voltage will be attenuated by the active preamp and would unlikely every hit the same voltage levels of input unless playing VERY loud. I would rather not run the digital volume control on the DAC and give up the bits that it uses, and when playing DSD, there is no digital volume control (1-bit signal).

Thanks for the guidance. So far, aside for when the signal gets distributed, the sound with the tube buffer in place is very pleasant.
Andy

This is the GB for XEN designed cases for the corresponding GB for PCBs and component sets.

The cases are produced in Europe and will start production in Jan 2020.

The objective is for the cases to be ready for delivery by the time members build the PCBs and need to test the build.

Cost per case set ( 2 Cases )( Power and Signal ) is €650 + shipping.

All materials and finishes as per EUVLs specs and design.

Payment on confirmation will be 50% total cost, remainder prior to delivery.

GB end date 5 Jan 2020 GB now Closed.
Shipping method will be fully traceable but final solution still to be determined. some work better for some countries others require different method....learned that from the DAO Headamp GB !!!....

Final List

Lbud4 — 1 Case set - CONFIRMED - Data Sent - Payment 1st installment -
JBdV — 2 Case sets - CONFIRMED - Data Sent - FULL payment - CASEs sent -
Auro — 1 case set - CONFIRMED - Data sent - Payment 1st installment -
Morde — 1 Case set - CONFIRMED - Data Sent - Payment 1st installment -
S610adam — 1 Case set - CONFIRMED - Data Sent - Payment 1st installment -
soldersober — 1 case set - CONFIRMED - Data Sent - Payment 1st installment -
JoeyDD — 1 Case set - CONFIRMED - Data Sent - Payment 1st installment -
markus22ch - 1 case set - CONFIRMED - Data sent - FULL payment - CASE sent -
Horio - 1 case set - CONFIRMED - Data Sent - Payment 1st installment -
Arthur 1 case set - CONFIRMED - Data Sent - Full Payment minus shipping.
Dennis1 case set - CONFIRMED - Data sent - FULL payment - CASE sent-
Some images as examples:

Hi all-

Working on a 9505 (2nd generation, I think - XLRs at the bottom, bananas at the top, & SMD input stage). It warms up and gets noisy.

I've found comments that the drivers are the prime suspect here - MPSA06/MPSA56, Q14 thru Q17.

Seems simple enough to swap but happy to hear from anyone who's been here before? Thanks.

I'm looking for a 2 channel amplifier board that could work with a transformer that I already have that outputs 38.5v-0-38.5 and 14.5-0-14.5. I'm looking to drive some desktop speakers and some statement floor standing speakers in the future. As far as what class amplification I am unsure what to go with. I have found some boards such as https://www.ebay.com/itm/265784869001?hash=item3de2034089:g:L3EAAOSwvZpi1O55 but in my experience some chinese boards can be somewhat hit or miss so any guidance would be appreciated.

Merry Christmas!!

I have a 7.1 channel Pioneer Elite VSX90 receiver that has a failed output transistor in one of the front channels. This amp uses the obsolete Sanken SAP17 Darlington pair transistors with 5 pins. The P channel device is blown which has internal thermal compensation diodes so I can't really just make my own Darlington pair like I have done before from two discrete transistors.

I only use the two front channels of the receiver and so I do not need all the channels. My question is can I just remove both N and P transistors from a channel I won't be using as donors to install in the bad front channel? My thoughts are as long as I don't connect a load to the channel where I removed the output transistors from nothing bad should happen. With both N and P devices removed there should be no DC present at output to trip protection. So long as there is no load connected the driver transistors shouldn't blow up when signal is present. I may even be able to disable the rear channel that I plan to take the transistors from within the settings of the amp, that way there no signal even goes through that channel that has the output removed.

What concerns me is the feedback loop. I don't have a schematic for the amp so I'm not sure if there is DC feedback that will damage the drivers if the outputs are removed.


What say the experts? Will this work or am I losing my mind?

Maxi Jazz (Maxwell Fraser) of the highly influential British band "Faithless" died in his sleep on Friday night (23rd December 2022) aged 65.

https://www.bbc.co.uk/news/entertainment-arts-64088168

Hello all
my Hifonics Thor Vii powers on, orange power led but no audio. I powered it up after a long time in storage, it worked OK for 5 minutes then I lost all audio, any thoughts on what could be the issue?

I checked TL594CN the board is marked 5v and +12v next to it, the corresponding pins have 5v DC and 12v DC, two other pins say Out they both measure 00.1v dc
So pin 9, 00.1vdc
Pin 10, 00.1vdc
Pin 11, 12vdc

Pin13, 5vdc
Pin 15, 5vdc

Entertaining the idea of having a case milled for my Aleph J. What do you all think about top mounted heatsinks?
Partly inspired by the Mola Mola audio gear, they have very attractive top plates.

Hello lads, I'm dealing with a sounddigital power 35000.
We have some shorted output devices that send the entire amplifier into protection.
Unfortunately it's my first 35000, so I don't know what the output devices are.
I only know that they are abraded with the wording "L3.
I am well aware that SOUNDIGITAL is reluctant to provide part numbers, but unfortunately the official assistance in Slovenia is the last resort, because it is very slow, going, waiting, repairing, returning.
If someone is kind, he can also contact me privately.
A thousand thanks.

Hi,

I discovered this site recently while looking to purchase a new amp. Even after buying one, I found myself coming back. I have no background in electronics or diy audio, but got interested in amplifier design while I researched for my purpose. My first thought was to take a theoretical approach, learn from books, but the complexity made me realize that I would never get to the "build" phase, so balancing book learning with doing seemed the best bet. The weak link in my system is probably my phono preamp, and 6L6 and others were very supportive and helpful, so I decided to start with a Pearl II.

My goal with this thread is not to create a guide to a great approach to building a Pearl II, as I do not have a great approach. It is really to do two things. First, it will likely help me. Forcing myself to write down what I am doing will make sure that I really think it through, don't skip steps, know what I know and don't know. Second, it is to with any luck help other beginners who are thinking of taking up the hobby. At times the threads on this site are way over my head, and I worry that I am missing things (I am) and that this will lead me to make mistakes (it has). Possibly, by going through my thought process, it will help others who are at the same level.

Also, there is the chance someone who knows what they are doing will say "you are making a mistake!!!" which would be helpful.

When I decided to build the Pearl II, I made two decisions: I would start with the power supply, and I would start with the case as opposed to the pcb and other pieces. The focus on the power supply was primarily because the parts were cheaper, so if I screwed up it would cost me less. Also it seemed less clear than the main board, so I decided that I would try to tackle it now to avoid frustration later. The case just seemed like a good idea, and it was, if I hadn't screwed it up, which I did. But that is the point of these posts, I suppose.

One last thing: this may take a while. I have work/family that keeps me away from hobbies for days at a time, and I see this process as learning first, finishing second, so I will likely go sideways and backwards at times.

People should feel free to post or send me notes, but please remember my beginner status. I will respond but won't aswer what I don't know. There are experts here who will!

Amp came in with a blown power supply. I replaced all PS drivers, gate resistors, and about half the FETs. Good drive signal.

Amp draws excessive current but appears to power up. I removed ALL rectifiers and PS is working just fine. Then I put rectifiers in for the Class-AB side and amp works fine. Rectifiers installed in the Class-D side; and something is wrong. Amp is using IRF640/IRF9640 output transistors which are not measuring shorted. I removed the driver board with the F16/B52 ICs and the amp powers up just fine without excessive current draw.

Im not 100% positive what to look at next. Either I was going to remove the IRF640/9640 outputs to the troubleshoot the driver card (Type 1), or possibly try powering the amp through a current limiter.

Hi,

I planned to design the zen amplifier that will apply BJT instead of MOSFET. Could anybody tell me which BJT should be applied for 10W zen amplifier?

Goodmorning

Years ago i have build the Buffalo II,and a friend of mine loves it.
So we bought a Buffalo III in the marker place.....
The Buffalo II was quite easy,but the III was a differtent story for me.....🙄

The power supplies are working fine but it stays muted....
After better reading of the manual......
I came up with 2 problems:
-I think i need a Sp/dif level converter,it uses only once source.
-how can i check which firmware is on there?
With te second version all the dipswitch settings seem te be inverted.

Hi, I’m wondering if anybody has experience with both the B&C ME75 and the JBL 2380A

What I really want is a nice, non-cracked pair of 2380A to replace the cracked one in my system that I could possibly repair myself, but nobody within a few hours drive will sell me one or a pair for a reasonable price.

This has me looking at the all-aluminum alternative from B&C (a decent mfg from what I can gather) the ME75… they look very similar visually and dimensionally, however the ME75 has a wider throat opening and the curves are sharper, which makes me think the response would be more peaky, and directivity more beamy.

I will be using this horn between 700 ~ 8Khz with a 2445J driver with a radian diaphragm in a 3-way system crossing over into a Beyma CP25 or JBL 2405. I’m not so worried if the slope of the response is different since that’s something I can easily compensate for, but not peaks/internal resonances. but if it’s beamy around 8k, that’ll be a problem 🙁 Especially since i’m very content with the way the 2380A sounds in my setup

"Getting real, strong 20 hz output from a loudspeaker is no mean feat. Going lower than that is subwoofer territory.

Gemme Audio proudly introduces the revolutionary VFlex technology, based on a unique Focused Pressure Field loading method that extends low frequency reproduction below the human hearing threshold of 20 Hertz using small drivers and enclosures. The new Vivace loudspeaker is our first model based on VFlex technology.

The Vivace are no ordinary speakers and they go LOW, real LOW, lower than 20 hz in most room conditions... That's quite amazing performance for any speaker, but their most stunning feature is not that they go that low... It"s that they can do it with a single 4" driver! Imagine what we can do with a larger driver!"

...

"Gemme Audio is aiming to offer its new VFlex line of full range loudspeakers early in 2007. After many tests and listening sessions, we've finalized the design. Utmost rigidity allied to awesome look and sound will be the hallmarks. We sincerely believe that our VFlex technology brings a revolution to the loudspeaker market. Nobody can imagine the sound of the VFlex loudspeakers when they see the small drivers. Nobody is prepared to hear full 20 hz. output from a 4" driver. But this is all real as listeners and NRC testings can testify.

Here is a comment from a reviewer waiting for a pair of Vivace : "...if you can make it a full range speaker, I think that would be incredibly awesome". Here's another comment from a web forum member : "You seem to have found the audio Holy Grail."

We'll be offering two models in the VFlex line as a start.

For the single-driver, horn sound afficionado, there will be the single-driver Vivace, offering "real" full range sound, from as low as 20 hz up the 18,000 hz, using the Fostex FE108E Sigma 4" driver in a very rigid cabinet, finished in real wood. The next model, called Tanto, will be a two-way tower, using a 6" driver paired to a Vifa ring radiator tweeter, offering bass that rivals 15" driver designs of yesteryears. Both models will offer small tower, resonant-free cabinets with sculpted front panels that are sure to offer a very high WAF!

At this moment, the look and finish are still on the drawing board but photos should be available in early January 2007.

Stay tuned to hear more about the Vflex models going where no other small driver loudspeakers have gone before."

For more look here http://66.130.192.248:9081/gemmeAudio/

What do you think? I would really like to know how the "VFlex" acutally works?

Regards
Mike

I want Ntp3000 Arduino Code ....I tried a lot To make this code....But I can't make this code...Can you help me.... Please