The iec socket on the F6 amplifier uses a fuse on both the line and neutral. Should the neutral pole have a larger amperage fuse?

Hello,
could some expert please confirm whether this is an original Altec 515B cone or an aftermarket one. Never seen such a cone on original Altec speakers, hence my question. Could maybe made by GPA?

Hi there! Has anyone tried modifying a HIP4080 amplifier circuit to use a different half bridge driver?

I always found that NEO 3 pdr is a nearly perfect tweeter excepted the frequency response.
When I studied the construction, I found that this tweeter sufering of difraction because of the magnets in front of the diaphragm.

So I've design some flexible resin shape to bond on the tweeter surface (on both side).

This shape cancel the diffraction effect of the tweeter housing

It's 3D printing with formlabs flexible resin:


It's far more effective than I though, nearly perfect response (green curve after modification, red before modification)



I will give up the waveguide! :green:

## Update: I ended up buying an STA-1000D ##


Hi there. Long time since I've been logged in.


I've been running an 4x IRS2092 amp that I built myself out of L15DSMD boards and a big SMPS. Been quite happy with it. But it's not the most detailed amp, and it's not particularly quiet.


Then I started researching again, a couple of weeks ago. I'm quite keen on the Icepower 125ASX2 modules. But there's a lot of questionable Icepower modules on Ebay and Ali. They seem pretty hard to source inside Europe, unless it's from Chinese sellers with EU stock.


That's when I ran into the IMG Stageline STA-1000D, that has Pascal modules. But from my understanding, these modules are as basic as Pascal Class D modules can be. But then I started looking at the other Stageline AMP's, and the 400D and 800D uses Hypex boards with Hypex SMPS's.


The 800D uses 2 UcD400OEM V7 modules and 2 Hypex SMPS400 V14 modules.


I reckon from reading in here, that these UcD400 boards should be quieter and sound better than my IRS2090(L15DSMD) amp. There is also balanced input, and my Stream Magic has balanced outputs, so there's that.
I can't seem to find any comparison of the UcD400 to 125ASX2 anywhere. But with these boards I should be pretty sure they are not fakes at least.
I like building amps, but with 2 kids and a pretty full schedule I won't lie. A ready box containing these modules would be a lot easier to play with and modify.


Or does the OEM boards sound horrific and I should move on?


I need to do more research. If anyone has some experience or remember some threads that I can't find - anything would be much appreciated.


Source of information: Opinion on IMG Stage line STA-400D amplifier with Hypex modules | Audio Science Review (ASR) Forum

and: Finale di potenza basato su Moduli Hypex dal suono hi-fi
Link to manufacturer: IMG STAGELINE: STA-800D



Pictures of the innards:

Hello fellow audio enthusiasts!

I have a scooter sound system project in the process and I have run into a few problems! I have searched high and low for solutions and I have gotten so so many different answers and opinions. Heres what I'm trying to do

3 weeks ago I bought an electric scooter (The Raptor) and I have desperately been trying to figure out how to power my small 23w Sub that I took out of a 2.1 with sub PC speakers (Logitech Z4's). My first attempt literally almost killed me. I laugh at my major stupidity now but in all seriousness I could have died or at the least been seriously injured.Long story short I watched a video online on how to turn a car battery into a battery back up with a 12v cigarette lighter adapter. I then went out and got a 200w power inverter. I plugged in the speakers as is (in the original box). At first it worked awesome. My first test of a 20 minute trip went smooth. However my 2nd trip of an hour went horribly bad! The battery caught on fire while I was driving and caught my back trunk compartment on fire. Lets just say my bike no longer has a trunk lol.

I have been doing some research on the SLA batteries that my bike uses but I'm told that I would only get at most and hour of play time out of a charge. Which is actually pretty good for me since I never really ride the bike for "hours" straight.

Anyways now that you have a bit of background to what I have been up to here is what I have done so far and where I'm at.

I decided to try and power the full range speakers (both are 17w a piece) with an amp from a pair of USB powered pc speakers. So far they work fantastic. I bought a USB battery back up @ 3.6v and 2800 mha to power it on my bike. I took out the sub speaker and amp from inside the sub box.

Here is where I need help. I was hoping to be able to use the chips and diodes etc on the board I have and remake a new amp board specifically just to power the 23w sub. I have a better then average skills with a solder iron and I can follow direction with great precision but when it comes to knowing the details of what each chip and diode does is beyond me. I have no clue in where to begin to make a new amp board.

If someone could take a look at what I have (Pictures at bottom) and possibly help me find the proper instructions on how to build the amp and maybe any extra parts/materials I will need, so that it wont take a ton of power to run I would be so ever grateful!

FULL AMP BOARD VIEW:




SUBWOOFER SERIAL NUMBER:


AMP BOARD ID:


STA540 Amp Chip:


JRC 45650 Amp Chip:


TL074CN Amp Chip:


DIODES ETC..










Any help is greatly greatly appreciated! Thanks so much!

I have the components for Tony Gee"s Mezzo Galactica I built a variation of 6 years ago. I have cabinets also if you happen to live in Arizona. Although they are not like Tony's. I used the same Seas Excel T29CF001-E0038, the same PHL 1130 but, because of availability, I had to use Ciare’s NDH 15-4 instead of the NDH 15-3. I also used the same crossover design with components of similar quality. These drivers have not been abused.

Seas T29CF001-E0038... $200 for the pair.
PHL 1130..................... $200 for the pair.
Ciare NDH 15-4............. $325 for the pair.
Crossovers..................... $400 for the pair.

Shipping not included..

Thanks,
Evan

Could not elevating heaters on a KT120 SE cause it to howl like it’s oscillating? I just built the amp and it was amazing for about an hour then it began oscillating and the only thing I can think of is I didn’t elevate the heaters. I’ve checked all connections and voltages and I am at Witt’s end. Ideas appreciated.

FS: Almit SR-LA LFM 48, 1mm solder wire, 250g pack.

I have for sale 250g pack of high performance lead free solder wire (Almit SR-LA LFM 48, 1 mm). Few cm were used, bruto weight is 288g, so like new.

Price: 30 EUR + post costs. Payment via PP.

Hi guys

Im totally new to the Rabbit hole of Audio Appreciation.
I havnt even listened to a high end audio set up before, so i dont know what my listening style is yet.

I am about to put together a pair of GR Research diy "Bravo" speakers.
But i am unsure about what to use with lining the enclosures.

They recommended lining them with a product called "No Rez" which is a specialty product of a type of double density foam.
Unfortunately its far to expensive to import, so it was advised that i go with something like vinyl tiles or butyl rubber dampening mat.

To be clear this is about reducing vibration of the enclosure not about internal resonance/reflects or whatever its called (a complete noob here)
Although, in thinking about it, i would not have thought that the No Rez did anything for resonance of the enclosure because i was under the impression that it required a certain amount of mass/weight added to the walls for that where the No Rez is just foam.

After doing a bunch of reading online, i am trying to decide between two options.
Butyl rubber sound deadener mat or mass loaded vinyl.
And im leaning more to the MLV unless someone has good reasoning otherwise.

One concern i do have about the MLV, is that with its intended application in vehicles it is advised that you use a Decoupling layer with the MLV because it apparently is more effective when appied with some give to it as opposed to laying it straight against a rigid surface like the sheet metal of a car door ect.
So you lay down a thin layer (1/4") of closed cell foam as the decoupling layer and then lay the MLV on top of that. Would that be necessary with lining a speaker enclosure or would that use case benifit more from it being rigid against the walls of the box?

They are a 2 way ported speaker made from 3/4" MDF (well 18mm because im not is the US)

As a side inquiry, if the No Rez in the set up of these speakers isnt for resonance of
the enclosure itself, would i need to stuff them with something to replicate what ever it was ment to do?
Because even though i dont really know anything about the audio world yet, i do know that every component of the original design of these speaker matters.
From the little that i have learnt so far, i know that Danny from GR Research doesnt do anything to his speaker designs that doesnt matter, so changing one little thing will effect the intended sound of these speakers
And because i have no experience in this field, i wont know if i have messed anything up and i want to start off with these speaker just as they are meant to be so i can adjust and upgrade everything else around the speakers as my taste and appreciation grows knowing that the speaker sound just how they are meant to.

And yes i am aware of the irony of that statement in a post about changing the component of the speakers that i want to stay just as they are meant to be.
But when it costs $200 to ship a $50 product from the US to AUS, some compromises have to be made. Hence the search to find a suitable comparative alternative.

Thanks in advance.
Paul M.

Take a look at figure d below, from here Electro-acoustic models

It appears to be possible, using a torus-like baffle, to spread the interference nulls in space and time, so does something similar to this diagram actually become a viable option?

Got a mail from Mr. TI with this link:
ANALOG-ENGINEER-CALC Calculation tool | TI.com
Downloaded and installed it (it runs local on your PC), and checked out a few functions.

Screen shot shows function to find gain error versus bandwidth.

Very, very useful! Kudos to TI for making this available for free!

Jan

Hi All,

I was wondering if anyone still had any LU1014 for sale, i've had two 36v 600va tx sitting around for some time gathering dust, and i though it about time i would put them to good use in the form of an F3 build.

Cheers

Hi,

I would like to buy Twisted Pear Buffalo 2 PCB with trident regulators.

I have posted the .pdf article: LX-mini Analog crossover in the Articles
section of FIRST WATT

Hi.

I just got an Audire Forte. I checked the DC offset and one side is solid at about 10mV while the other is all over the place between 95 and 130mV. Keeps changing around and it doesn't settle anywhere. I tested the amp and it sounds fine. No hums, no pops. I'll be doing a recap on the driver board soon so I hope that will take care of the DC offset problem. I know this amp uses the MPQ6600 and I don't want to start looking for one. Any suggestions?

The channel with the good DC offset seems all original. The output transistors are the originals MJ15022 / MJ15023 (3 pairs). The channel with the DC offset issue has output transistors 2SD555 / 2SB600 pairs. These look like an old replacement and you can also see that some of the caps on the driver board are different. My question is: if they are working OK do you think I need to replace these for original MJ15022/MJ15023 pairs? Could these be causing the DC offset issue above?

Thanks.
Elias

NOS P&G faders. 5k. PGF3020. 28 pieces available. $17/each

Anyone in USA have a kit they no longer want? Would prefer to make it myself rather than buy already built.
I know they are currently available on DIYA store but silver front plate not available until April 2022
Might have to go black if lose patience.

Hi friends , ive bought sec hand para hca-1500a for cheap as untestesed ,the seller said its maybe fuses.

inside one fuses of the r channel was blown and replaced with correct one.

Anyway ive plugged it with light

bulb limiter for precaution ,the amp work normal ,dc offset ok 0mv ,bias ok (15 mv) without light bulb limiter.
The amp playing normal and stable but ive notice by ear some distortion , and then connected to amp to my test bench with 8r 100w dummy load both channels and to rta on pc.

Then i saw the problem . R channel distorted

L channel clean.
after all the tests i cleaned the amp , checked and cleaned all the fuses and their holders,repalced the protection relay ,dexoit pots ,resolder joints and wash the pcb ,tested all the semic' for shorts checked the bias again on both channels and the problem not solved.

Still got distorted r channel.
Thanks

Eldad.
Im adding pics in pdf files.

Hello,

First of all, I am a newbie on tube gear but understand that it is dangerous poke anything inside high voltage device like tube amplifier so I will take extra caution when I measure the voltage.

I had a couple of tube amplifiers before but it had testing point on top plate so not needed to open the bottom plate.

I got fixed bias 300B SE tube amp that does not have testing point so need to open the bottom plate to measure the plate voltage and plate current.

1) To measure the plate voltage, do I connect MultiMeter one probe to Pin 1 (Filament/Cathode) and the other probe to Pin 2 (Plate/Anode)?

2) I am not 100% sure where to put probes to measure the plate current. (scratch my head).

I have two multimeters with aligator clips on each end of probes so will measure both voltage and current simultaneously without moving probes to be extra safe.

I attached actual unit photo as well as schematics.

Thank you very much for your guidance in advance....

Actual Unit Photo underneath 300B tube socket


Schematic

I am trying to do some room analysis with REW. Soundcard is an RME ADI2, with a UMIK2 as mike.
Trouble is that REW refuses to use the UMIK2 for input. It correctly identifies the RME as the output device, but insists to use it also as input device.
If I look in W10 audio settings, I see the UMIK2 and can set it as the default mike and it tests OK.
I have tried both with RME's MADIFACE driver as well as the Java driver.
Any tips of what I might be missing?

Jan

Hello,

I always wanted to restore a solid state amplifier after playing with tube equipment. I wanted it to be something special, exciting, unique and decided on a V-Fet Sony and ended up with this TAN-8550, despite all the warning signs around it.

So, as soon as it arrived, I checked the famous diodes, and they were bad. That result didn't give me any hope for the V-Fets, and sure enough, 4 out of the 12 were shorted. (Interesting enough, only the 2SJ18s seems to be shorted (2 from each channel) and the rest has the same Vgs value as they are factory matched, I think.)

Diving into the dust and the dirt of the online auction sites and using search phrases like "assorted to-3 lot", "nos transistor lot", "Sony transistor to-3" and alike, I could be able to score a couple 2SJ18s with different ratings (all being 53 and above, 53 being the lowest mentioned transistor in the service manual). After my luck run out, I have reached some people from here for more spares and ordered a few 2SJ18s from different sources.

Now, my question is, after hopefully having more than 4 what supposed to be 2SJ18s, how can I match hem among themselves and with the ones that were already installed in the amplifier. I have this simple curve tracer from PEAK the DCA75 but the voltage settings are beyond me. I am a "push the green button, wait for the OK sign" kind of a guy when it comes to solid state. In the manual, it mentions about which resistors to change to which value if unmatched transistors are to be used, but I want to get as close as possible.

It would be great if this thread turns out to be a "screen capture" of today, the challenges, difficulties and problems that some one could face if they chose to restore a TAN-8550 and also a how-to / not-to guide, as I haven't seen any complete thread about the restoration of this amplifier. And some threads date back to 2002...2005.

Best Wishes,
Dirk

Hi i tried to gett a LarsHolt 7252 fm module to work but it Will not do it what
I am going to with it somebody that has schematics obuit the module

Lasse Sweden

Hi. Here I am again with my vintage amplifier copy.
Just when I thought that I was finally done something has to go wrong again...
I was working on the vintage amplifier that I copied from the old solid state radio. It is based around ac187k, ac188k complimentary pairs for the outputs and silicon transistors for all the other stages. I know it is not the best circuit (no thermal compensation or emitter resistors) but now I really want to finish it plus that circuit was in that old radio from the 70s and still works after rough conditions in the workshop of my grandparents.
Anyway. As I was finishing up the whole amplifier module it was working fine but one channel shorted the outputs without any overheating or anything strange. I just touched the input for "buzz test" and it shorted after 1 second.
The other channel works fine for now but I am scared of destroying another pair of transistors...
So here are my questions:
1 was maybe 16v too much for the circuit?
2 what is the maximal safe voltage?
3 can it be converted to silicon transistors?
4 why do you think the transistors failed (they were stone cold!!!)
I personally suspect that I damaged the transistor in previous attempts (I accidentally swapped emitters and collectors around) and it broke down.
This was supposed to be a fun project but it turned into frustration... But I want to finish it now because I want to understand what went wrong.
Here is the circuit diagram of the radio and some pictures...

Hi, I am planning a build with the Dissipante 3U chassis. I was thinking to use the same power connector from the back panel kit, the Schurter 4304 6090 IEC Power entry module. I found this on Mouser, however it specifies IEC C14 or C18 compatibility. Looking for mating power cords on Mouser, no luck. Is this actually the correct power entry module for NA use? I'm certainly no expert on power connector specs, any feedback or suggestions welcome. Thanks.

The most common complaint about diyAudio I've heard over the years is that you have to often wade through thousands of posts to find out how to build something. Often there are little nuggets of information interspersed over the posts, and it's very easy to miss something. For this reason, getting started with DIY audio has been much harder than it should be, especially for newcomers.

When I originally started diyAudio, it was actually to collate online a list of audio projects people could build. Over the years it's grown into much more than that of course, and I am blessed to be a part of this amazing community. However having a single place to find a project, get the information you need, and start building has always been elusive.

I'm happy to announce a solution for this problem - diyAudio Guides, available at http://guides.diyaudio.com.

Right now it's in "beta" and we're putting in the work to set the communicative and visual standard that others can follow. It's not currently linked from diyAudio.com, nor is it open to the public to contribute. But when it's ready, I'm hoping it will form an integral part of the community, especially for newbies, and it will be open for every member to contribute in the way they feel capable - projects, build guides, construction technique, soldering tips, anything that can help other members realize their DIY dreams.

diyAudio Guides runs on another platform, and has a "SSO" (Single Sign On) that is linked to your diyAudio user ID. When you go to Guides, you should be automatically logged in there, and you can comment straight away on any individual step of a guide (which I think will be very helpful).

The plan is that at the end of each guide the corresponding discussion on diyAudio is pulled through or you are directed back to diyAudio for more detailed discussion. We'll work that out later. Right now, it's a bit of a hack, but once we move to our next forum platform over the next few months, we will be able to custom code a nice solution to deeply integrate Guides into the structure of diyAudio.com itself so it's one cohesive platform.

So.. this is just the first announcement. Right now we've only got one guide in there, that's the Amp Camp Amp March 2018 Build Guide. Pretty soon we'll have all of 6L6's other amazing guides, and over the next few weeks work out any bugs. If you have a guide you'd like to contribute, please get in touch via contact@diyaudio.com - we'd love to have you be a part of this early-stage fleshing-out of diyAudio Guides.

I'm very excited about the future for diyAudio in 2018. New forum software, the diyAudio Guides section, and the store finally (hopefully!) being permanently in stock of beginner level kits to get people started in the hobby. We'll be very busy keeping the engine room of diyAudio running...

If you have any feedback, comments, complaints, or bug reports about diyAudio Guides, please post it in this thread.

I need some recommendations for enclosure plans, drivers and most importantly the amplifier modules.Id like to spend no more than $4000.00.
Feel free to chime in if you think I‘m making the wrong move, I just want to consolidate space and have a less intrusive looking audio system.

Anyone tried these 6A 650V GEN6 SiC Schottky Diode as filament bias in DHT?

hello , im puzzled by the freq response of my dual 6" bass drivers , wired in parallel , 3 way foorstander ( SD Acoustics 'SD5' , from 2001 )

drivers unknown, no labels , but seem to be giving an incredible in room response of +/- 1db 30-1khz, which seems bizarre ( well that seems incredible to me )

basically, im trying to lower the crossover point to 200hz , but i can not get the woofer to stop outputting , its pretty flat to 1khz ( I used a textbook filter of 6.7mh + 100uF 2nd order ) ....those values should produce approx a 200hz crossover with 4ohms

the drivers have combined DCR of 3.3R , plus 0.8R inductor DCR

please see the graphs , one taken 10cm away, with the above filter applied ( both 1/48 smoothing)

other graph is with no filter , taken 40cm away

- I dont understand how 6.7mH + 100uF can produce a crossover point at 1khz?

Hello, thanks for stopping by.

I build my own tube amps, pres, FX and things, and have an opportunity to bid on some older equipment that my company needs to move on. They just purchased some very expensive high end scopes, signal generators and power supplies.

I was hoping that some of you might comment on these models so I may better pick one or two to bid on. Thank you! There is:

BK Precision 3017A Function generator
Wavtek FG2C Function generator
Leader LFG-1310 function generator

and for power supplies:

BK Precision 1746B DC power supply 16V @ 10A
Harrison 6286 power supply DC 1-24V, @ 12A

I notice that the the BK and Leader function generators have sweep and/or burst functions which I'm thinking are good features for testing audio equipment.

There is also a Fluke 8050A digital multimeter which looks like something good to have around besides my typical DMM.

Thanks for commenting!
Best,
Phil Donovan - building up an electrics work/build/test bench

I'm trying to decide if I want to build the VFET kit I won in the lottery, 2nd round. I'd like to know if anyone has compared the characteristic sound of the M2 with the VFET amp. I've built 2 M2s and this amp has become my every day amp driving my horns, even replacing my DHT amps. I just don't know for sure if I want to build another low wattage amp. Any experience is appreciated.

Regards,
Milkduds

Hi i recently purchased one of the above amplifiers in working condition off trade me but would like to know more about the company ect or even get some service info schematics ect.
judging by the date codes on the devices i would say the amp was manufactured about the middle nineties but have been unable to find any information on the net any help would be greatly apreciated.
Thanks Peter.

I'm still building my 3-way which is a combination of a bass-reflex low cabinet (2x Visaton W250S), a mid horn (Visaton DR45+M300) and high horn (Visaton TL16H).

But I'm unsure about the low-mid. They (Visaton literature) let that mid horn go down to 800HZ. Looks low for such a speaker for me. While at the same time going up to 800Hz for 2 25cm speakers looks high. The distance between them is coming below a wavelength.

Now I have from a previous build a couple of Fostex FE208Ez around. The full-range I did with them isn't for me as they lack seriously in the low end. But they do sound great in the voice range. They have a good efficiency as well. So it looks as if they might be a good mid-low (400-3000). I dropped the parameters in an online calculator and this shows up as a 4.2 liter closed box. Seems very small but OK.

Anyone experience using this speaker this way?

I dived deep into this subject like many others. It would be great if we could use this thread to just share our projects and our experiences. Might they be technical (implementations) or listening reviews (subjective no problem it is just about sharing your experience)

I would like to avoid discussions if this all make sense, again, just sharing your work and experience.

Reason is, we might pick up ideas on implementation or also find inspiration to try out other clocks in our DAC systems.

having said so, also non DAC applications would be welcomed here (like ethernet switches for example or ADC ?)

Looking forward to your inputs and many pictures. I will take the lead with Post #2 🙂


.

Hi guys, I had a dead Xetec Gravity G500 monoblock on hand, the power supply keep dropped into the short circuit protection mode. Someone has messed with it before but seemed no luck yet more torn PCB pads.

After I remove the module with defaced chip, which I think most likely to be the Class-D modulator, the amp was able to power up without any output.

I wanna ask is anyone had the schematics or able to identify the defaced chip?

I'm considering trying to build an IoT soundlevel meter and wondering if modern 24bit ADCs can support such a use-case.

I'm hoping for a dynamic range of about 120dB, and power draw around 10-20mW (just for the ADC not including draw from the driver and other components). Not too sure about other specs yet.

I saw the upcoming ad4630 which with about 20 averages and scaled down CNV clock gets within the ballpark I think. Prototyping with that package doesn't look fun though and I don't know when the part will be available.

LTC2500 looks like it could be an option, again with some use of averaging.

Anything else I should consider?

If this is my first ever ADC design project and I'm also pretty green with MCUs should I start with an easier task and work up to this? I was eyeing the older AD7766; although it won't meet my specs it looks a bit more simple and like I may be able to use it with an Arduino fairly easily. Suggestions welcome.

Hello all, just picked up a pair of mk iii’s, and looking for advice. I’m new to working on tube amps, but I know what sounds good to me. I’m using these guys, through a Tad-150 preamp (pretty decent Chinese/slightly modded by a guy that used to sell them in Chicago) , and vandersteen 2ce sig II speakers.
Pretty revealing speakers. I listen mainly to rock, so I want it to sound right-
Full and driving. Don’t care for classical, or being able to determine the orchestra
Hall size. Do listen to plenty of acoustic music, jazz, whatnot- and I’ve been a musician for 30 years- so I know exactly how certain instruments sound.

First impression of these dynaco’s- they are good amps. Very musical, with great separation. Not much to complain about. They are stock- rebuilt with new caps, selenium rectifier changed. 550 filter caps.

However- they are a little lacking- a bit thin sounding. Reverb stands out way too much. They’ve got decent low end, and plenty of highs, decent mids, but seems like something is missing. And that reverb area- really sticks out.

I’ve read tons about them, and am not sure what to attack. I thought maybe negative feedback- and I disconnected the 680 resistor and added a 250k pot after it, and it did make a useful control, but the range I got from the pot was way too much, slightly moving it up made a huge difference- mids popped out huge, and gain went up big time. This would be a nice control to have, but this pot was way overkill. I also tried the feedback at the 8 ohm tap, but that was a little too much as well. Anyhow- like I said, I’m new to this and have no idea really- this feedback system is beyond me, and it might not be the right area to mess with.

These mk iii’s replaced a TAD-60 power amp, fairly similar- 60 wpc from 4 kt88’s. It did have a feedback control, and it was quite useful. The tad might have a bad opt, is the only reason I switched.

So what do you guys suggest? I’ve done speaker placement , and my room is small, so nowhere else to go there. Acoustic guitars are missing their full sound. Too thin. Something is missing, or maybe something is standing out too much. I’m guessing missing.

I chose these amps, from what I read about them, good solid amps, USA made, every component easily replaceable, with good transformers, simple- and probably a good intro to messing with tube amps. And I needed something to do locked in the house! Which they have delivered already in spades!

Hey all,

I work for a small production company and was recently tasked with installing XLR inputs on our Fostex 6301B full range monitors. I simply drilled a hole in the housing, rivet mounted the XLR input, and (I think foolishly) wired the pins of the TRS connector to the XLR connector.

Now the speaker has a few symptoms it didn't before. Sometimes it will operate smoothly, sometimes it will get fuzzy and distorted, and other times the volume will modulate while the signal cracks and distorts.

I am wondering if a direct link with the pins is the issue but am not sure. I would love some experienced help with getting the speaker operational again.

Here is a link to the circuit diagram.

Fostex 6301BEAV Service Manual (Page 9 of 12) | ManualsLib

So I recently received my Amp Camp Amp kit in the mail, and then promptly went on holidays for almost a month and hadn't had a chance to check out the parts that were included until now.


Turns out that the speaker terminals included are ferro-magnetic (i.e., some form of steel plated with gold or somesuch) rather than a non-magnetic alloy such as plated brass. Why does this matter? Well, after reading through Douglas Self's Audio Power Amplifier Design (6th ed., 2013), on pages 426-427 he talks about magnetic distortion introduced into a power amp's output by ferromagnetic speaker terminals. Turns out this is a thing, and introduces detectable third-order harmonic distortion. Does anyone know where I can obtain speaker terminals that are guaranteed NOT to be ferro-magnetic? The usual sources have all managed to fail me so far, which is annoying. I've probably ordered close to 100 dollars' worth of terminals from various sources (eBay, various Canadian electronics distributors, Parts Express) and all of them have been attracted to the magnets I've waved over 'em, even though they've all claimed to be plated brass.

Hello!

I have old broken Brüel & Kjær 1023 sine generator and need maintenance manual or just schematic diagrams for it.

Can anybody help?

I have asked manual or schematics direct from Brüel & Kjær and their agents, but they state, that they dont have product support for those old equipments anymore.

I think most of the complicated parts of an amplifier design can be taken out of the equation by using ICs. So as a beginner who doesn't know much electronics I figured this maybe a good point to start. I want to be able to design my own amplifiers using chips such TDA 7294, LM3886 or even some class D chips. I want to be able to look at a commercially available amplifier using such ICs and improve them by swapping parts or using same parts in a different arrangement. I don't know the functions of resistors, capacitors, inductors in a circuit other than that resistor hinders current flow and can be used for voltage dividers and that a capacitor stores charge and opposes change in voltage...basically textbook high school physics. So how can I actually do what I want to? I have flipped through the pages of Bob Cordell's 'Designing Audio Power Amplifiers' and it seemed too advanced and over overkill for my goal.

Mike Holt's Forum
Electrical Calculations / Engineering | Mike Holt's Forum

Is Mike Holt using the same XF software that we will be using here? (Understanding that there is much customization available to forum operator.)

It works OK over there.

BTW, do NOT butt-in there. Mike is The Teacher (books and paid courses), those guys are professionals, and very arrogant about putzes and dabblers.

Was reading a thread MARK started ref a freebie Rega Goldring GR1.2
Well I bought it off him.last week, pretty much in the state he showed in his pics.
Loved the tip from someone about the cerium oxide, to add to that, a little tip from me, (use this on steel splashbacks)After all the elbow grease use Johnsons Baby Oil and a soft microfibre cloth to give it a shine.
I'm quite close to finishing the refurbishment, pics attached, just the cartridge to sort (hopefully Mike's soldering holds up)
Mike i'll let you know how she sounds soon hopefully and thanks for the bargain 😀

I’ve been lurking almost daily for the last 6 months trying to absorb and soak in as much information as possible. I’ve learned a lot to the point of making the decision to join the DIY game and build some amps. The plan is start with a ACA mini, then Tokin SIT amp (when details are released) and maybe eventually a M2X. As I have read and learned I am beginning to I stand Nelson’s love of the 2nd harmonic character of his designs especially when the 2nd harmonic is a negative phase.

My question is what effect does balanced input into the amp have on the 2nd harmonic characteristic? Does the common mode rejection inherent in a balanced topography cancel this out?

Bigger picture. I started following/reading after picking up a XA30.8 amp. First time ditching tubes in 20 years and not really looking back. In the 6 months that followed a XP25 and XP22 showed up. My understanding is all of these are fully differential/balanced topographies. at the same time I remember reading that part of the change from the .5 to .8 amps was a greater emphasis on the negative phase 2nd harmonic. Would running XLR from XP22 to XA30.8 negate those changes? And further let’s say I did run XLR from pre to amp and liked the presentation would I expect a similar effect on a FW J2 using balanced vs single ended?

And lastly, would effect would running the XP25 to XP22 balanced and then single ended to the amps have harmonically/sound presentation wise? Clearly if I do build the mini ACA, Tokin SIT, and M2X I’m looking at singled ended input into those amps.

Thanks fo any input!

PS: I’ve been working on a laundry list of tools to grab for the amp building projects. If I was going to post a thread with specific questions about tools needed to complete something like M2X or VFET front end boards should I do that here since it’s Pass specific for the equipment/tools section?

My DIY tonearm project continues.

I got my parts from McMaster. Right now I'm using the aluminum spacers (instead of the stainless I also ordered) because they're light. The overall height of the arm is 1-3/8" but you need some clearance at the bottom for pivoting action. I'm trying to keep the height down because my platter/motor won't be too terribly high (they are pulls from an old Technics SL-6, if you recall).

I'll likely replace the screws with flat-heads to reduce the overall height and compensate for the tonearm wiring having to clear that front screw on top. My tonearm material is just 3/16" thick, so I might end up needing to order undercut screws (should have thought of that). I'll try countersinking carefully.

The wire I'm using is from a travel mouse, it is very fine, probably nearly 32 AWG. You can't tell from the pic but the section of wire with the insulation still in place has the shield wire running into the same hole as the rest of the wires, and then it wraps around the top part of my pivot component. So ground will be carried down through the pivot. I don't know at this point whether I'll even need a ground, but this is my pending/untested solution if I do.

The counterweight idea worked out extremely well. I can adjust weight and azimuth (because the counterweight can be shifted left/right). Right now I'm using washers and a nut/wingnut as my actual counterweight. Once I get further along, I can come up with a properly-sized more elegant solution.

The entire thing is very light, and extremely responsive without being wobbly. I think I could further lift the "headshell" area to do an even better job of aligning the stylus with the pivot, due to my low center of gravity counterweight method, without making for a wobbly unit.

The steel nut you see where the cartridge should go is my attempt at approximating the weight of a cartridge. It is just 2-sided taped in position.

I need to find a very inexpensive cartridge and screws to mount it to my tonearm for initial testing. Also the proper clips to go on the end of my wire (the ones there were from a shell for the mouse connection, and I can't make them work for a cartridge for reasons I won't bore you with).

I'll keep watching eBay for a crap cartridge and screws and cartridge clips. The little things start to add-up, as the shipping starts to eat into the cost on this stuff.

Looking for a pair of new or used Cinemag CMLI-15/15B transformers.
Shipping will be to Canada.

Please let me know if you a have a pair for sale.
Thank you!
Pierre

Hi All,

I have a few of these Blazer PCB, s that had the trimmers replaced, one turn with multi turn. Not sure if they are correct.
Board has a 2-5K. Two have 5k and two have 10k. Will post pics. Feel free to comment on anything that may need upgraded or...

AND, how and why to adjust this single trimmer? For crossover point or BIAS?

Thanks

P.S.
Not sure if it is 500w.

Some of these complementary Mosfets for sale! Anyone interested ?

Regards,
VS

After building a pair of Decware DNA rear loaded horns, I became enamored by the sound of the Alpair 10P speakers. So clear, so coherent. If only they had the bass to go with that sound. Don’t get me wrong, they’re impressive in the DNA horns, but they won’t shake the house. After coming across the Manzanita thread, I thought two GRS woofers in parallel should bring the efficiency up to about the same level as the Alpairs and make the crossover a piece of cake. Long story short, built a set of open baffles similar to the Manzanita Ultra Plus but using the Alpair 10Ps. I could get them to sound wonderful using an active crossover but just could not get a passive put together that didn’t sound like crap. The Alpairs went back into the DNAs and the Ultras into a corner of the basement.
While on a trip to Walmart I found a Blaupunkt touch screen stereo on clearance for $35 with two 6.5” speakers. Since my old truck needed a stereo, this was a no brainer. I tried out the speakers and they sounded amazingly good for something you can buy for about $25 a pair but were lacking in the bass department. They didn’t go into the truck but I tried them in a transmission line alignment that I had and was very impressed by them. I almost stopped there but happened to notice the frames with the two GRS sitting in the corner. Cut the ears off the 6.5” Blaupunkts and into the frames they went. A Parts Express 4 ohm 100hz crossover was wired in as a simple first order and a pot used to pad down the Blaupunkts. Amazing sound out of a total of about $200 of parts! I’ve replaced the pot with 8ohm resistors and may have to do a little shaping but it is damn close as is. The Blaupunkts are basically operating full range and naturally fall off in the lower octaves. The 9mh inductor of the crossover tunes 4ohms to 47hz but the slow rise of the GRS woofers combined with the inductor ends up pretty flat to 200hz before tapering off. It just works.

dear all,

i am joining with a question that is probably simple for many of you but i werent able to figure it out.

i was trying to make a concrete wiring diagram of james giffitn’s tapered line array example that he mentiones in his great 2003 paper and of which i join the relevant page here.

there is also my humble attempt to draw a diagram for the first two (uniform feeds) wirings (3 groups of four in parralel and simultanously 4 groups of three).

can anybody help me with that, please? i seem to be getting all sorts of short circuits as you need to do multiple series and parralel wirings to the same speakers in the array. we see several problems there: direct connection of several speakers (not series any more only) and shorts.

many thanks in advance for your help. guess this is also interesting for other people.

best wishes to all members

Can't edit thread name, it's possible?

TIA
Felipe

Hi Guys

I have an Ashly XR1000 crossover that I generally like but would consider an opamp upgrade. It uses LT072s and other dual opamps. What would a be a good modern alternative for unity gain stability and active filters? t
they are all on dual sockets for easy replacement.

Thanks,

Scott

Aleph J PCB/Part set, include the most needed parts


- Transformer Müller Rondo

- Semiconductors (matchted 2SJ109/ matched Output Stage transistors, ZTX)

- PCB´s include PSU

- Dale/Panasonic resistors

- Elna Silmic II Caps

- Clarity ESA coupling caps

- Neutrik XLR

- rectifier

- main switch

...


250€ plus shipping from germany

Can anyone tell me the difference you would notice in the sound between the basic red and the more expensive models of the cartridge style? Thank you.

hello!

i am looking for a dsp solution for my 4-way PA system.

this cheap behringer/minidsp stuff just wont do it for me...

it needs to be reliable, sound good, have digital in, iir+fir capabilities, and 8 digital outputs.

it can be a naked board, doesnt have to be in a case.

would be nice if price is under 3k, but im open to all price ranges.

danville signal seems to have boards that fit these specs, however i am a bit overwhelmed by their descriptions, i am not sure i should order one without understanding any of their user manuals.

can anyone point me in the right direction?

cheers, lisette

I've heard of people using wood glue, but that seems to be alot more of a hassle than it needs to be. Does anybody have any tips? I try to do it with watered-down wood filler, which seems to work ok, but I don't know if that's the difinitive way to do it or not.

SOLD

I've just obtained a lovely pair of Goodmans Magnum K2 speakers, which are 3 way, and with large bass drivers.

When I've taken a good look at the bass drivers it looks like the plastic (shiny and black) coating has started to delaminate around the dust cap area, which is not good. Although they still sound really good.

Is there an easy/simple way to resolve this?

My first thought was to see if I could gently press it back against the cone material, and see if it would stick back again. However I think the plastic coating has shrunk, which is why it's delaminated. When you try and push it back, its tight.

My first idea is to put the speakers on their back, and using a heat gun see if I could gently stretch it, and possibly get it to stick down. This would be by keeping the gun constantly moving and gradually increasing the heat until it makes the plastic malleable.

However "before" attempting this, I thought I'd reach out to the combined wisdom on this forum and see if there's a better way to do this, or easier.
I know I could maybe try re coning them, or get them re coned, but I'd rather do a fix if I can.

Please see attached pictures.

Thanks, Rob

Hello learned colleagues,
Does anyone know which Sanyo board does the Roksan Attessa Transport use?
I am trying to tune it properly and because of lack of manual, I'd like to get one from another player using the same board.
The designation is 1B10007700 which in Google bring out a single result from someone asking the same question (but has more pics) and is about Morgan Audio DeVa:
Morgan Audio 'DeVa' CD Player - UK Vintage Radio Repair and Restoration Discussion Forum

Any clues?
Cheers
Roman

Been out of the sub game for a while and need some advice. I have a pair of subs that I would like to power with something around 800w per side. 8 ohm each so probably paralleled do a 4 ohm load.
What options do you recommend? Plate amp, diy, prosound?
Cheers.

I do Have this question for both amps : The Blues Junior and the Blues Deville
Is there any way to completely disconnect the Amp part and use only the preamp by connecting the preamp out to another extrenal amp?

Let’s say the spec calls for a 50uF capacitor with a tolerance or +/- 20%. Could I safely replace it with a 45uF or 55uF capacitor, since the new part is within the tolerance of the old part? Or could there be problems because I’ve moved the center of the tolerance window up or down slightly?

911EDA, Inc. provides full electronic product development services. Our services include PCB design using all major software tools, as well as schematic design and capture. Engineering services include schematic reviews and audits, hardware, software, and firmware design. We also offer PCB manufacturing. Since 2000, 911EDA has provided our vision to clients within the consumer electronics, industrial, medical, military, and telecommunications industries. With offices in San Diego and Boston, we support customers across the United States. https://www.911eda.com

ESP P101 boards



Pains me to sell them, but at 66 and recent eye surgery.

All high grade parts from Mouser USA. Except matched parts from AmpsLab USA.

Prefer USA shipping. If it fits it ships USPS medium box 1 add $14.



I WILL SHIP REGULAR USPS IN USA ONLY.
I HAVE NO PayPal account. Do WalMart $ transfer, OR 2 day money order.
NO PERSONAL CHECKS.

You get 4 boards and the parts on them. 2 boards were in a working amp for 5 years EXCELLENT SOUND. The other 2 were extras.

One is missing semi conductors and ONLY one working board has power transistors,

Used VARIC to +-15v, two 100 ohm safety resisters, and 60 watt lightbulb as per ESP site instructions for safe testing.



Plus you get a bunch of power transistors, WORKING??? Not sure on the testing, DMM only. Purchased MATCHED sets from AmpsLab, NOT CHINA.

ONE board is working and biased at .014v with 40-0-40.

R7 & 8 have 5.6 on all boards



My eyes are failing, so…





LINK INFO



https://sound-au.com/project101.htm

I build a headphone amp recently but I find the sound rather harsh. This is the circuit. Its driving some DT559 cans. Just for the record I would not use an OPT again. The result is ugly and the mains transformers couple into the OPT producing hum. Toroid's are better here but if you have the HT volts a WCF circuit would be a solution. The frequency response is fine. So the question is are headphones meant to be driving from low output impedance or are better on higher drive impedance?

I just finished building the Clearwave 4TSE towers designed Jed Kunz. I had previously built his Center Speaker which made watching movies so much nicer. I could hear everything and almost stopped using subtitles! Now that I have made the towers to replace some 25 y/o B&W speakers I could not be happier. Really, it is a totally new experience listening to music and movies.
The below link is to a YouTube video while making the speakers. Nothing fancy, but the idea comes across.
Clearwave 4 TSE Tower Speaker Build DIY - YouTube

BBC-style thin-wall cabinets. Why so special?

I have always found the lossy design to be interesting and decided to do some digging today as I haven't had much going on at work.

This thread is very interesting and I thought I would share it here.

It talks about how you can "tune" a thinner walled lossy box but not the standard thick walled boxes.

I have been looking at different driver materials and in the past I have found poly to be a bit over damped and "wooly" sounding. Some untreated paper can be a bit harsh if not properly designed. I was looking at Visaton and Arum Cantus. I am not familiar with their Aerogel or Visatons treated paper cones (almost plastic looking). How do they sound? I like woofers that perform well in the lower mids.

Hello,

I have the TI EVM3255 module that is not working and wondering if someone can help me troubleshoot the problem. I am a newbie in electronics and my knowledge is pretty much non-existent.

I bought the module but it was DOA. Texas Instruments sent me a replacement which is now working. I would like to fix the module rather than throwing it away. I need a subwoofer amp and this one will fit nicely.

When I turn on the amp, the FAULTz (D4) instantly lights up in red. No output at all when input and speakers are connected. Is it something that the faulty part/s can be identified? As someone who has zero knowledge, I do not know where to begin.

Any help is very much appreciated. Thanks!

Hello,

I am hoping that I could get some help on a starting point on this amplifier.

I have this vintage receiver. It has A LOT of sentiments value to me.
However this amp doesn’t have a lot of support. I can’t even find the electrical schematic for it.

What it is
University Sound ( A Division of LTV Ling Altec. Inc) Studio Pro 120A
From I am guessing the 60s- 70s

I would like to restore it, or even improve it if it is possible.
The other modification I would like to make is wire in some preamp out Main in Jumpers so in the future I could use this for my preamp for my Dynakit St-70

So the question is where would I start?

- Can someone help me identified which each board is for?

- I am guessing all the capacitors need to be replaced at this point in its life.
What kind of capacitors can i use to replace them?

- Identification of where I could source out pre amp signals?

Thank you for your help!

Pictures will follow soon

Over the last 6 months the diyAudio team has been busy planning, preparing and testing our much-needed shift to a new software platform.

We are planning to perform the migration mid-December.

Our current platform is now beyond "end of life" (EOL) which means it no longer has access to software and security updates. It’s important we transition to a modern and well supported platform as soon as possible.

There's plenty of upside however! Modern software means we'll get to enjoy a slew of modern niceties often taken for granted today, such as post auto-saving, drag and drop images, and a WYSIWYG editor.

The focus and vibe of the forum will stay the same - helping you find and build amazing audio projects with the help of the most passionate and generous audio community in the world.

The forum will be offline for around 24 hours during the migration. No data will be lost. All discussions, private messages and thread subscriptions will carry forward.

The new software (XenForo) is written by the same people who wrote the current software. While it looks different it feels similar. There will be a light theme as the default, a dark theme for night owls, and a classic theme that's as similar to the current look and feel as is possible.

A "clean slate" in terms of software means we'll be able to properly review and act on areas of the site that regrettably had to be retired over the last few years due to EOL issues such as blogs, articles and galleries. It also means we'll be unencumbered to pursue our mission - making discovering, building and discussing your dream audio projects as easy and accessible as possible.

For those who have been generous enough to donate to the forum in the past (thank you!), we're changing the name of "donations" to "premium memberships". The benefits for each level will be equivalent or better than what is offered now. We're removing the lowest tier and anyone currently on that will be bumped up to the next level.

The new site is currently in beta. Functionally it's getting close to ready and has pretty good feedback. Many thanks to the mods and a keen cabal of members who have been giving it a good working over.

For any members who are interested in helping with beta testing of the new site, please click here to register your interest.

Now is a good time for me to introduce Gerard.

Gerard (gerardv) is a long time diyAudio member but more recently our man-at-arms who has been championing the progress of the migration behind the scenes. He is managing the onboarding of beta testers, collating feedback and liaising with the development team. If you sign up above to be a beta tester, he'll be the guy who gets in touch with you with further details, when the time is right.

Lastly, THANK YOU to every diyAudio member for participating in this amazing community. It has been an amazing journey over the last 22 years and I feel we are just about to hit the home straight 🙂

May your projects be many and the smoke stay in,

Jason

I ordered an 8200r kit off of Ebay last week, and started looking for information on the build, so as to get prepared. I couldn't find any schematics, and realized that I might be getting a "Japanese Only" manual with the kit. Having made this discovery about a week after the order, I think it may have shipped, and I'm afraid that I may not have any readable instructions. I contacted the seller, and they said they would get back to me on whether they could get an English translation, but I haven't gotten an answer. I am in a small town in western CO, and I don't think there are any Japanese speakers here to help me translate. Does anyone know where I can get an English manual, or just the schematic? I am a retired EE, and know how to solder, so the schematic would be good enough for me to assemble the kit, though the instructions wouldn't hurt as well. Thanks in advance!

I got two bookshelf speakers for $20 US, figured I would try to build an amplifier to test them, but having trouble finding a good 2-channel chip. Any recommendations?

The Speakers are VB-15 Bookshelf Speaker | Klipsch

Hi,

For my current project I’m looking for a digital panel display that can display DC voltages up to (and slightly above) 600V. This meter has to be placed inside the amplifier control unit.

I know many people use the standard 200mV display modules, with voltage dividing resistors in front.

I want to see 600.0 instead of 0600.0 displayed. I want to measure many more voltages (like 400 V, -120V, -50V, 12V, 15V, -15V and 6.3V (DC, not AC), so I do need one decimal. It would be nice if the meter dan display the V symbol too.

So far I haven’t found the right meter for this. Any suggestions are welcome.
What do you use?

Regards, Gerrit

P.S. I intend to use a similar display for current measurements, by converting the voltage over the cathode resistor to mA readings.

Hi Folks.

This is my first post to this forum. So it's nice to meet you all.

I have a Technics SU-A808 which sounds great most of the time. But sometimes the safety circuit kicks-in and resets the amplifier. Then it comes back on and works like normal again.

Now I'm an Electronics Design engineer by trade, but not in audio. By business is Temperature & Humidity Measurement and Logging.

I puchased the Technics Service Manual online, thinking it would give lots of information. But apart from the circuit and a parts list, it's lacking good description.

The fault occurs when cold or hot. I have heated with a hair dryer and it doesn't trigger the error, and cooled with freezer spray and no change.

I have removed the board, and re-soldered the SVI3205B Power Amp Modules. The soldering looks very dry and cracked, and I thought this was the issue. But it made no difference.

Both main rails look ok at -50 and +50V.

I guess the safety circuit is tripping because there is to much dc on the speaker output.

The manual talks about adjusting the amplifer so output voltage. This is done by injecting a signal of 1kHz, 100mV in to the tuner input. Set Volume to MAX and adjust VR203 (Lch) and VR204 (Rch) for 14.0Vac +/- 0.2V. But I don't think this is effecting the dc output level, just setting up the correct input level to the amp.

When the trip occurs it can happen a couple of times in a row, but something many hours between. To I can't see any errors.

I guess I could discount the speakers, then disable to safety circuit, and when the error occurs try and check the voltages. But I risk damage to the amp.

Any advice out there?

How reliable are the SVI3205B Power Amp Modules, and how available are they. I would hate to bin this amp, the sound is just perfect for my old ears. It sounds great when playing my DVD-Audio Queen music through it.

Thanks for responses in advance
sNick

I just bought a tube preamp. It uses two 12AT7, one per channel, and I know it also uses feedback around the circuit. Gain is 20dB and output impedance is low, 200 ohms. What circuit(s) could this be? SRPP, for example? I'm just curious to understand this better as a newbie

This is the description of a simple fullrange and fast 3d construction technique, and also of applying DSP (by CamillaDSP) for frequency equalizing and interchannel crosstalk compensation.

Intro:

I do not like the performance of average, small PC desktop speakers. Neither do I like to clutter my desk with fair sounding, but, for a desktop, rather huge standard HiFi loudpeakers. And I do not like to spend as much as a pair of small genelecs would cost.

But then, I had a pair of spare Vifa Ne65W drivers. Along with some bit if corian board, I built a small, «fullrange» stereo dipole array, knowing that the performance would be very limited in terms of SPL and lower frequency range extension. And with a stereo base of 7cm, they would neither project an impressive, 3D stereo landscape. So, this small speaker was not intended for serious audio. but more so to be small and also optically to match the monitor design, and last not least, to resproduce some of the audio signals potentially emanating from the pc once in a while in a better than desastrous quality. No more. And no less. And this is what I need most of the time, when I am confronted to a PC sounding.

1.jpg

2.jpg

However, from time to time I wanted a slightly better audio than that, e.g. for music flics on youtube or the like. But still, I did not want to add further electronics gear onto my desktop. So, what to do? I decided to go for a solution à la convertible.

Construction:

Having some cardboard boxes (a leftover from a recent LED-Lamp buy branded «BUFFY Indoor»), I built some kind of a horn addon box, along with hot glue rods and hydroculture burnt argile speres. It was quite fun how quickly its rough structure could be assembled. As cardboard is very resonant, I filled all spaces with layers of hot glue and expanded argile spheres. Also this procedure is a very fast and simple, straightforward and iterative process: Disperse hot melted glue, pour a handful of spheres onto it, squeeze it a bit, then pour the non-adherent speres away/out. Then again disperse hot glue on this newly applied spheres layer again, pour handful of speres onto it … The glue and speres block gets quite rigid. The surface of the last, upmost layer might be soaked and brushed with white glue for wood bonds, in order to seal the whole thing. What finally came out, I called it a BUF Indoo. Don't ask why ...

3.jpg

4.jpg

5.jpg

6.jpg

Acoustics and measurements:

Now, how does this BUF Indoo behave acoustically? Lets see … Roughly, the desktop and the monitor provide a small pi/4 – space, along with the BUF Indoo radiating out of the corner line. Therefore, desktop and monitor might act as tow faces forming a semi-horn. Semi, because the sides of this semi-horn are left open.

For most of the loudspeaker measurements and filters post processing, I use Acourate. All measurements were performed at a space of some 70cm-80cm, the distance where I sit while spending time at the PC. A «high» measurement was made at my head height (red graph), a «low» one at the heigth of the desktop plane (brown graph), and an «intermediate» one (green graph) at an elevation in between «low» and «high».

Native.png

Low (Brown) at more or less zero elevation from the desktop plane and also at the height of the loutspeakers show a +-5dB behavior from 150Hz … 15kHz, which is quite remarkable for such a simple and crude setup. A single, decent +4dB … +5dB peaking filter centered at about 4.5kHz … 5kHz would provide an even better result.

Intermediate (Green) and High (Red) are roughly 15° and 30° out of the direct radiating axis of the BUF Indoo. The frequency response is much more uneven than inline which call for a more elaborate equalization. For practical reasons, I had Acourate then compute an averaged and smoothed curve (black) out of both responses.

DSP by Camilladsp:

Along with CamillaDSPs IIR filters, this black average could be reasonably corrected by three peaking filters and a single shelving filter: A fist, broad, low-Q peaking filter, attenuating -4dB at 500Hz, a second peaking filter boosting +3dB at 4kHz, and a third peaking filter attenuating -3.5dB at 8.5kHz. Finally a shelving filter of some 8dB centered at 2kHz will bring the response into a reasonably flat state. IIR filters declarations are very handy if you want to experiment with different sampling rates. One filter declaration fits all use cases, then.

Instead, I decided to generate and apply a FIR filter (blue), which roughly corresponds to the inversion of the averaged black response. Keep in mind that you might set the max. level of such a corrective filter intended for a realtime-convolution to max. 0dB. It is even wiser to set such a filter to a max. of -2dB … -3dB to be shure to avoid intersample clipping.

Inverse.png

A test convolution of this filter on the upper (red) and mid (green) response shows neat results for both cases. As expected, the (initially more or less linear) low response (brown) now suffers and shows more or less the characteristic of the corrective, inverse filter. Nota bene: If you mess around with FIR filters and different sampling rates, then you will need one filter (or one filterset in case of a multiway x-over design) per each sampling frequency you might use.

Convolution.png

DSP is really nice. Besides of the correction in the frequency domain as explained above, it is easily possible to implement also a moderate interchannel crosstalk compensation. In the pipeline section of the CamillaDSP configuration file, you have to first split the stereo channels into four subchannels by a mixer, then apply the cancelation, and then merge the four subchannels back into the two stereo signals, now including the cancelling information in each channel. Using some trigonimety, at a listening distance of 80cm with an interaural distance of 27cm and a loudspeaker stereo basis of tiny 7cm the interchannel difference of the pathways results to 1.16cm, which at a speed of sound of 343m/s results in a teeny weeny delay of 0.034ms to apply for the cancelling signal.

My desktop computer runs as a Windows 10 system. I configured CamillaDSP to use the onbaord Realtec S/PDIF soundcard/soundchip section as the shared capture device in loopback mode. This runs nice up to 192kHz. CamillaDSP outputs to a dedicated, internal PCI RME HDSP 9632 Soundcard in shared mode also. There is even no need for an amplifier. The phones output of the RME soundcard is just loud enough.

Outlook:

Thats it. It was a fun and somehow hilariously simple project. And as the BUF Indoo even has a somehow ridiculous optical characteristic, I consequently will leave the whole box as is: As a kind of weird cardboard-glue-and-argile-sphere agglomerate. No black piano stain. No. Not really … Such a piano-stained version might be the case for a next iteration. Then, maybe with some decent and optional sidewalls from the side of the monitor to the desktop also, forming some kind of four-walled-horn. Maybe. And maybe not.

Appendix:

The CamillaDSP config.yml (subject to change ...)

Hopefully someone can help. I recently built the 8600s with lundahl transformers. And it sounds fantastic. However, in my right channel the voltage starts out spot-on but then starts to vary. For example:

after 30 minutes.
TP3 101.1
TP4 109 one time then 29. Very strange
TP20 113
TP24 113
TP28 16

I quadruple checked the component placement and it lines up.

In addition, had an issue with one of the PCs 201 or 202 that the instructions indicated to put it one way and pages 22, the pcb chart, said another way - I put it the way on page 22 but maybe that isn't correct.

I checked the soldering but will check my solder on tube v1 pin 1, and PC202, and v4 tube pin 2?

Any advice would be appreciated.

SOLD SOLD SOLD SOLD SOLD SOLD



























SALE PENDING FS Bliesma T25A-6 Tweeters ONE MATCHED PAIR BNIB; ONE PAIR SOLD

Hello,

I bought these pre-covid for a build that was put on hold indefinitely. Never mounted, never connected. Only taken out of the boxes for pictures. Build quality is superb.

Solen sells them for $145 USD each + shipping; I can let them go for $200/pair + shipping and PP fee.

I'm willing to ship internationally at the buyer's expense but please don't ask me to undervalue the customs declaration.

These are matched pairs with consecutive serials:
SOLD Pair 1: Serials 00127 & 00128--SOLD
SOLD Pair 2: Serials 00129 & 00130--SOLD

See Hifi Compass's characterization of these excellent drivers: <https://hificompass.com/en/reviews/bliesma-t25a-6-t25b-6-t25d-6-t25s-6>

Features :

• 25mm aluminium-magnesium alloy dome with variable thickness for ultrasonic first breakup mode

• Extremely low moving mass for better transient response and higher efficiency

• Fully saturated neodymium motor with copper sleeve for low non linear and modulation distortion

• 2mm linear excursion and large vent channel for undistorted low frequency operation

• Narrow surround for less “soft dome” coloration

• Flush mounted surround and rear mounted magnet system for flat frequency response and wide off-axis response

• No ferrofluid for improved dynamics

• Underhung voice coil wound on titanium former

• Flexible and lightweight lead wires made in Denmark

• Thick aluminium powder coated flange

• Aluminium rear chamber with natural wool damping

• Gold plated wire terminals

• Recommended frequency range 2.2kHz-35kHz

Hi,
in the past (i.e. in my youth) I've successfully wound dozens of transformers, both power and output transformers, as well as chokes. I did it the, say, German way, using flanged bobbins and serrated insulation foils. Both are (were?) very common here and make winding a relatively easy-peasy job.
Now I've harvested quite a number of power transformers from cheesy transistorized Hammond organs. Unfortunately, most of them feature 115 Vac primary windings, hence aren't much of use for me in their present state. So I'm about to rewind (some of) them. Even more unfortunately they weren't wound on flanged bobbins, just rectangular tubes are there.
That makes me scratching my head now. What precautions do I need to do to prevent the magnet wire from slipping when it comes close to the edges?
Best regards!