Good day to all,

I am just starting to design my next pair of reference speakers. I have been through the many designs and styles, 2 ways, 3 ways, 4 ways, sealed, bass reflex, transmission line, and more, so I have a good idea what I expect and want from a pair of speakers.

My latest and most intriguing experiment has been full-range drivers. I am converted to the concept as flawed as it is, I had just grown tired of listening to crossovers messing up my jazz and vocals. As I have been listening to a lot of acapella music lately, you can always hear a crossover smear somewhere in the vocals. It is just too good to be able to listen to a sax run up the scale and it is smooth as silk or listen to an acapella quartet without the crossover humps or dips.

But(it is always there!) I am finding that the ends of the spectrum just put to much pressure on any single driver that I have heard, you give up good deep bass, and find the highs can be just a little too gritty for my ears.

So to remedy that, here is what I am proposing to do.

A woofer in a transmission line with a full/wide-range driver as the mid-range covering from 90Hz+- to 4,000 - 6,000Hz area where a tweeter or super tweeter will take over. Essentially a three way.

Lets look at each driver and what we want from it and why.

The woofer could be a 10" or 12" Peerless or Scan-speak, with a folded transmission line tuned to a bass cutoff of 30Hz or preferably less. I do not want tubby, fat, or boomy bass, I want clean, quick, fast bass, I will using this for music only. It would need to carry the bass up to around 90Hz and I want to use as simple of a crossover as possible, preferably first order.

The mid range - I want the full vocal range completely free of cross-overs, hence the low 90Hz, I have sang with good bass singers that can smash a C two octaves below middle C, which is only 65Hz, not many but a few. most of the vocal range is from A3 - 87Hz through C6 - 1,050Hz, with a select few sopranos shattering glass a few notes above that. A piano tops out at about 4,200Hz or so, above that you have mostly second harmonics happening. So by covering the 90Hz though 4,000Hz with one driver we completely eliminate all crossovers in the critical hearing, vocal and fundamental range of most instruments. I am completely annoyed with beaming that goes with most larger wide-range drivers, the largest driver I would want would be 4" preferably less. So here is my shortlist of drivers, the Jordan JX92S, Bandor 50AFSW/8, which are fine except are not very efficient. I am open to any suggestions you may have on suitable drivers. I would go for a Manger, but that is such a quick driver that mating a suitable woofer is almost impossible I am told. Again I want to keep crossover as simple as possible, and if possible use enclosure construction to work as passive crossovers. With the two above drivers, a high pass filter is unnecessary because of the roll-off of the drivers. Most likely a low-pass would be unncessary also because we could just tweak the high-pass on the tweeter to pick-up where the mid-range is starting to tire.

Tweeter - 4,000-6,000Hz and above . I have not given much thought to a driver here and would love to hear you recommendations, again remember I have no love for beaming or narrow sweet spots, I prefer a wide, full listening area. So I am assuming a 3/4" tweeter or maybe even a ribbon would be what we need.

I am hoping for a passive cross-over consisting of a first-order low-pass for the woofer, and a first-order high-pass for the tweeter. I may decide to pinch off the top of the midrange just to avoid too much glare and muddiness because of expecting to much of the mid-range in complex and difficult passges. Plus some possible pads to bring everything into line.

OK, fellow full-range junkies, let's hear your ideas and criticisms. I know there are some very experienced full/wide-range listeners in this forum including Planet10 aka Dave(with some very interesting driver ideas), Dice45 aka Bernhard, Mohan Varkey, just to name a few. A budget is not really an issue here, except like everyone, I am always interested in spending less instead of more.

Cheers,

Surf, Sun & Sound

Hi;
I'd like to post about some UX improvements that could be made in CSS.

• These buttons aren't lined up 🙁
  
  
  
  
• Certain buttons/actions lack feedback:
  • "Okay" button is grey, whether or not you have chosen an avatar or not. It's usual for this button to turn 'active' when the action is available (after uploading.)
  • There is no hover feedback on Okay
  • There is no hover feedback on Delete for the purpose of warning a user they are performing a destructive action.
• The Paid Member icon seems a pixel too small for the star to center properly (this is a lower-dpi or lower-zoom related issue.)
  
  
• The Paid Member icon could use a text feedback/marker. I did not know what this icon was until I opened the debug console.
  In the below code, I found that the user banner text (which is in bold/strong html5 tags) is hidden by virtue of setting the font size to 0, inherited from the parent container that holds both the icon and the text (<em class="userBanner diy_paidUser">.)
  
  Spoiler: Offending code - Spoiler for size

  HTML:

  <em class="userBanner diy_paidUser">    <span class="userBanner-before"></span>
      <strong>Paid Member</strong>
      <span class="userBanner-after"></span>
  </em>

  CSS:

  .userBanner strong {
      font-weight: inherit;
  }
  
  .diy_paidUser {
      font-size: 0;
  }

• The icons on the side bar under a user could use some improvement in consistency. As with precious display, the UserBanner that shows paidUser has a tag (in <strong>), but hidden. The OP/Original Poster tag does not; but it's also styled and sized differently, leading me to believe it might be simply an oversight 🙂.
  
  
• Some more cut off text :s
  
  
• Hovering here does not turn the text white to contrast it with the purple - or it's not supposed to turn purple
  
  
  
  
• This icon has done a disappearance trick.
  
  

Hello everyone!

I was wondering if it was possible to take a stereo signal from, say, the line input of the computer, route it through LADSPA plugins that would control the filtering and delay of the signal, and then output it to the physical outputs of the sound device.

I recently accomplished this using JACK in this thread, and while it was quick and easy to do, I've found that asound.conf has always eluded me, and wanted a lower-level challenge 🙂

I have seen that there are a number of threads here that document how this work is done when chained to a music player's output, but I would like to do the same with the live input, if possible, without the need for an application.

So, to recap, is it possible to:

• Receive the stereo signal from the line input
• Split the signal into 3 stereo pairs
• For the first pair, use a low pass filter for Bass
• For the second pair, use a bandpass filter for Mid
• For the third pair, use a high pass filter for Treble
• Output each pair to a different output (I'm only using one audio device)

Thanks for the help!

Like the title says...looking for a TI TPA3251EVM or TPA3255EVM....

I'm in So Cal.

Have bought one of these SMPS on eBay:

https://www.ebay.com/itm/154164805607?hash=item23e4f03fe7:g:uzgAAOSwlxRfVvpt
I actually also have one running +-70V and a new one for +-35V, all for supplying class d amps.

The +-70V one did work and is running in my main amp right now. I checked the additional supply voltages, and was a bit surprised they where a bit off, not delivering +-12V or +12V, as I recall they where a bit higher, but thought this was down to these to being regulated, and as I'm regulating the +-12V down to +-6V on the amp board, and as the +12V which I referenced to the -70V for supplying the Gate driver, it all worked fine.

But with the +-35V supply, I'm getting only +-6V and +6V!!!!!

Anyone have the same experience with these SMPS?

I'm wondering if the transformer is the same for all the different output voltages you can chose from?? Or whether this is a fault altogether.

As the output is not regulated you'll need more windings for getting 12V on the +-35V SMPS, than for the one giving +-70V!
There is a small resistor on the bottom side of the pcb, and I'm wondering if this is actually how they change the main output voltage, and that this is not done using different transformers!

I have previously designed BJT complimentary output stage based
amplifier. It is first time i am going to do a mosfet Class AB amplifier.
I want it to be Quasi Complimentary NMOS output stage, preferably IRFP240
as Models are easily available
How to protect mosfets from blowing up due to oscillation as the
amplifier will work up to 300Khz?

Design Target:
*2W class A region before moving to AB
*300Khz Bandwidth
*At least 100V/us Slew-rate
*Low phase shift [ Less than 6degree]


Ripple eater are taken from Wolverine Amplifier

Please help me to setup spice to find out THD, and output stage.
How to measure slew rate and check out phase margin under Lt-spice?

Preliminary Input and VAS stage , i have attached

Edit: Removed *Low Phase Margin [Preferably Under 6d]

Hi all,

I have recently acquired and completely restored and calibrated old NRI Model 70 Tube Tester.

It works perfectly, but I miss a lot of tubes in my chat (on build-in roll).

Mine roll is indexed as NRI-70 3-53," (assuming from 1953) and the previous tester's owner included another Tube Chart Roll, indexed NRI-70 3-59" (assuming from 1959).

I know it's old model, but the latest data I found was in NRI Journal from 1962, stating the latest Tube Chart of the time is indexed as: "NRI-70 1-61".

So now I know that I am missing at least two years of Tube Chart updates for sure and possible even more (not sure what year NRI stopped updating Model 70's charts).

Does anyone have later Tube Chart for NRI Model 70 than "NRI-70 1-61"?

Or have any helpful information about this tester, especially compatible charts I can use or data how to add a new tube to it's chart, etc?

Thanks in advance!

Old Hush

P.S. I have the original manual and schematic already.

Hi:

Will you be adding a recommended BOM to the listing?

Regards,
Scott

Silly question but if I replace one of the resistors in a CRCRC filter with lets say a 6AU4 damper diode (25 V drop). Will that RC stage still behave effectively like one of the filter stages or does it not? I understand an L can replace any resistor. But what about a damper diode? Assuming I needed to drop 25 volts vs dropping it with a resistor, did I lose a filter doing this?

This Pioneer was a gift, it is the only phono player I have, would like some ideas of what if any cartridge upgrades there are (as it seems there arent too many for p- type). I dont want to do a rebuild, as turn tables seem too fiddly to for me to get involved with. Any suggestions?

I've gone cross eyed looking for an affordable amplifier or amp board that can supply at least 1000w to drive my subwoofers. Can anyone point me in the right direction?

First - Happy New Year 🙂

For more than a year now I'm more or less working on this project. Now I thought it was time to share everything with you. So depending on how you like it - here are all the files for you. (Next Post)

It is a Broadband Driver Unity-Horn - I call them the "SB-Horn V3" (Sub-Broadband-Horn Version 3)

HF & MF consist of a 2" full range driver. At the moment it is the NE65W-04 Sometimes I find the sound of the NE65 a bit "metallic". Therefore tests with the Tymphany TC6FD00-04, which has a paper membrane, will follow. As LF the horn is "loaded" with two 6.5" Dayton Audio DCS165-4 in BR configuration.
BR Tuned to 35Hz.


Sound familiar? Yes - I found this one on the net a year ago & thought, surely this can be "reshaped" -> https://quint-store.com/h-a-v-o-f-a-s-t-fun

So I searched until I thought I had found the right horn. Then I have the contour Abgeformt & completely redesigned. The print time per half-WG is about 20h with a 0.8mm Nozzle (Creality CR-10 Max).

This is the Waveguide: PRV Audio WG45-50 2" 90 x 40 ABS

Here you can see how I molded & re-constructed as Unity:


RAW-HF response 0 to 50 deg horizontal (gated @4.1ms due to Room issues):


Since it is extremely difficult for me to measure properly at home below 500hz. Many series of measurements later I had "a feel" for what the speaker does. So please be a little merciful with me 🙂

What I did - compared between the gated measurents, the near field measurement and the ground plane. If you then look at Vituix predicted cross-over & compare with the smoothed near-field measurement - have I made exrem nonsense here?

By the way - if the input-mearuement data for vituix is gated at a certain point, vituix seems to interpolate in a way:


Here are all the measurements:








ATTENTION: Unfortunately both of my boxes have a huge problem! Check out the impedance measurement of the LF. At pretty much 180Hz, my 3D print resonates pretty strongly. I printed my horns with 100% infill. Nevertheless, this resonance occurs there. At high volumes, this is then unfortunately strongly audible, at low volumes not.
My guess - as soon as the woofers are screwed to the 3D print, the screws "pull up" a few 3D print layers. These then resonate with each other - which is exactly how it sounds. A friend who rebuilt my horns for his bachelor thesis does not have this problem. So it is probably "only" due to my print.

I recommend: Instead of screwing the woofers - glue pins into the holes of the 3D print. Then "lash" the woofers against each other.

Looking for a service manual for any of the listed amplifiers. Ideally I'm looking for a TAS service manual but any of the others would work. If anyone has one or a link to one it would be most appreciated. Thanks.

Hello, i have one DAC board with 2 TDA1541A S1 (1crown) with one CXD8003 and one CXD1244. (from old Sony cd player CDX-A2001).

I will like to recyle this dac, i will like add one SPDIF receiver on this board; With one DIR9001, wm8804, cs8414, or one IC compatible with this circuit:

I need reclock the CXD1244 chip with the same clock of the DIR9001?
Or i can use the same 3/2 clock pin from cxd8003 chip?

Please i will like reuse this board with one spdif input to the CXD1244 chip.

I sorry for my bad English.

Thank you.

I'm planning to build 6 of the bandpass sub design from 18 Sound that relies on ports:

https://www.eighteensound.it/media/...NfNjY5XzE4c291bmRfMTJCQU5EUEFTU0tJVC5wZGYiXV0

But THIS looks much smarter. Same 6th order bandpass, no?


Is this a good idea?

So, I can convert the 4 tube ports to either 2 regular slots of same x-section or 2 expanding slots of the above design (this greatly simplifies the build and adds rigidity to the box):

How do I convert the original tube ports to narrowing chamber/expanding slots? The angled slot combo looks like an elegant solution with less cuts to be made and that's important.

What do you guys think on the three options and how to model the box in the 2nd photo?

thanks!

What could possibly be better than a Pass component?
Well, of course, that would be two (or more) Pass components!
This thread is devoted to all builds and system designs that make use of multiple Pass components. Am going to kick it off with a Dual Preamp just completed that houses the Korg/Pass B1 in the same chassis as the WB 2018. This allows you to shift directly between tube and SS pres. Also, as a way of accessing my Pass amps (along with 2 retail ones) the design is five in and five out (see the front panel below). Five source media directed to any of five amp sets.
Wonder what a tube pre sounds like on a M2x? No problem...just select them. And the WB 2018 with a 300B tube amp? Same thing – dial them up.
This is the 3rd Korg B1 I have built but is the first WB2018. From the moment the WB 2018 was fired up, I was entranced by the sound – very clear, precise, and dynamic. No noise anywhere and the paths are discrete for each preamp.
Will be looking forward to shifting back and forth between these pres in the next week and determining their ideal selection – what incoming sources they prefer and what are their subtle characteristics.
There was a certain amount of complexity to this build and must thank Gareth at AudioSy.net for his PSU boards and the occasional answer. The wiring is dense and a larger chassis would be an improvement (this one is 330 x 230).
If there is any interest in this multiple Pass philosophy, will share two other recent builds that use a dual theme. Let me know.

Hello All,

After building Zaph Audio SR-71's and being very impressed with them, I am going ahead with a vented TMM design built around the Dayton RS225P-8A and either the Dayton RST28F-4 1-1/8" fabric dome or the HiVi RT2C-A planar isodynamic tweeter.

My first puzzle is whether to keep the woofers acoustically isolated from each other or not. I'm concerned that if the output of one differs from the other even slightly, then not isolating them may cause interactions that degrade the sound. I've searched extensively by myself for advice on this and found little to no mention of the benefits of either route so thought I'd see what the very skilled folks on this forum have to say. I modeled each design in WinISD and see that using one vented enclosure results in a smaller box, 62 liters vs. 80 liters if each is isolated (each design tuned to 35Hz). My preference is a smaller box, but not if that results in reduced sound quality.

Any data or thoughts would be greatly appreciated.

1x unmounted Tribute Audio Inductive Volume Control - $500 OBO

(I will include the Elma 04-1344 with purchase.)

has anyone built a line array speaker cabinet using the Eminence LA-WG14 line array waveguide? I'm just tossing around options and seeing where it leads me.

​

I've tried running two of these (actually TPA3118) mono boards for a stereo amp and ended up with just a ton of power supply noise. Is there a way to overcome this?

I have a situation where I'd like to run 3 of these boards on one supply.

Hi folks

I just received a used, new to me, Mivera IcePower 1200AS2.

Who here has a buzzing noise coming from theres? With nothing, just power I am hearing a good buzzing sound even sitting 15 feet away. Nothing appears to be damaged on the inside. Tried different power cords and outlets throughout the house. No Change

Is this normal - Plays music fine and no noise through the speakers, this is coming right from the power transformer. I've googled high and low and found nothing related to this

Please tell me this isn't normal.. There was a minor dent to the bottom of the box it came in, pretty well packed. Would a flat drop jig something around?

Attempting to build the equivalent of a Niles SPK-1 that uses a 5VDC trigger instead of 12V. Basically, I want to use a switched USB port on a TV to control it.

It's obvious that I need a relays for the positive lines, but do I also need to switch the grounds? Or can they all be commoned together?

Or does someone already make a box like this that I'm not aware of?

Greetings and happy new year! I've been learning about valve amps recently and would really like to build a "hifi" stereo amplifier as a project.
I like the idea of recycling old components into something new and have seen a lot of videos on youtube of people doing just that.
I've been offered 2 identical reel to reel tape recorders which are destined for the tip. I'd like to reuse some of the internals to build into a new circuit. Obviously each tape recorder is mono but each has an output transformer so I'll have a matching pair (assuming they are usable for this purpose).

The valves are: ECC83, ECL82, EM84.

Can anyone suggest a circuit that could make use of the parts from the machines? Would I be able to make a stereo amp out of these or would I have to have 2 separate amps in the chassis?

I found a circuit diagram for the tape recorders online:

Hi everyone

I recently built a small amp mostly from parts i already had, the whole thing was simulated in ltspice and results were satisfying. The amp works and sounds fine however power output is lacking, my speakers are efficient (~94db) but i find that i have to turn up the volume quite a bit before i get satisfying output. So i went ahead and measured it on my newly acquired scope which showed me that i barely get 2W of output power.

Simulation:



This gives me 4.8W at 1.3% THD. The output transformer model i used comes from Robert McLean's excel spreadsheet.

Reality:



This is just before clipping, fed with 2.2Vpp at 1KHz from a signal generator. Load are two 50W 16 Ohm resistors in parallel. My math here is as follows: 11.4Vpp * 0.3535 = 4.0299. 4.0299² = 16.24. 16.24 / 8 = 2.03W.

So my question is, did i do anything wrong here? Is my basic circuit and measurements correct? I'm still quite new to tubes so there might be an obvious mistake somewhere that i just couldn't figure out.
I do realize that output transformers in ltspice aren't really that accurate as they have no losses and generate no distortion but the power output shouldn't be that far off right?

Pearl hum, I bought already built. Any advise where to try to reduce hum. First I thought it was Grado ref sonota 1, there known to hum so tried MI Soundsmith did same thing. Strange thing it changes when you bring tonearm towards spindle at beginning of record it's louder in right speaker. Go towards spindle hum fades louder to left speaker. Sounds like a non shielded cartridge having problems with motor but both cartridges do it. They have never done that on other preamps. It increases with volume. It's not bad at low volumes. Looks like ground mounted on Back for turntable ground is maybe not grounded in the best place will try that first. Are there some common places to look for hum, thanks for any direction.

Hello,
I have measured the HT on a 300B amplifier power supply and there's a small voltage variation occurring. The voltage reads in average 542.0V on the multimeter, but it drifts +/- 1V over a minute. I made a small 1 min video of the measurement, would really appreciate some feedback. The PS has LC filtering and uses two 5R4WGY tubes for full rectification. Is this normal? if not, what can be causing it? Rectifier tubes?
Can't see any cap leaking... there are a lot of them, it would be a nightmare to test them all.
The measurement was done without any signal (inputs shorted)
Thanks in advance
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I built these amp stands about two years ago, to hold a pair of VTL MB-185s, but of course they should work with other amps, too. Total size is about 22" x 12.5" x 2.5". The 'usable' size, so to speak, is 20.5" x 10".

They are made from solid maple laid over plywood, for a 1.5" thick base, then finished with solid maple around the edges. The stands then sit on Dayton Audio spikes.

The stands are generally in great shape, but there are a couple dings on (what was) the back edge of both stands, from where the amps sat.

Asking $100, which is about parts cost. (The spikes were $40 per set.) I'm looking to send them to a good home, not to make money.

Shipping will be actual cost. I have a box I can modify for use but haven't actually boxed the stands up yet, so I'm not positive about the details. But it ought to be about 28lbs, and about 28x20x8.

Please see the ad here:
https://www.usaudiomart.com/details/649813441-maple-amp-stands-22x125x25-built-for-vtl-mb-185s/for photos.

Riki

I spend a lot of time working on my computer these days, and I have recently enjoyed listening to speaker-demo videos in the background. I would love to hear your recommendations for more!

The best I've found so far are from Kenrick Sound. They have hundreds of lovely classic JBL restomod speakers, and they seem to put some effort into getting high-quality audio and video capture of their demos.

Where can I find more of these kinds of videos to binge? Speaker type and music genre isn't important to me (though big exotics are fun), only the quality of the capture.

TIA,

Bill

Hi everyone .
since i'm an audiophile crazy it's been a while that keeps buzzing in my head one thing (i don't know why). 😀
a speaker that uses many permanent magnets each with its own voice coil (same principle as the cone loudspeakers), all together moving a single large membrane (as in planars).
practically a hybrid that combines the characteristics of two different worlds, magnetoplanar and cone magnetodynamic loudspeakers.
exist ? to you it appears that some builder or some do-it-yourself has tried to build one? .
how do you think it would be?

Anybody who has more information or even schematics of this DAC? Unfortunately no signal comes out anymore
although the signal is apparently aquired (LEDs show successful aquisition of the signal). Anybody who can help please?

Hi,

So i would like to be able to quickly jump from a crossover point to another while listening. to be able to make decisions

Is there a way around this?

For example going from 1khz cross to 4khz etc...

Manu

Hi all.

I am thinking of building some MKB 230s, as low mids kickers.

I have modeled them in sketchup, and am wondering whether they can be slightly adapted to maximise material efficiency, as BB ply is now so much more expensive.

So to maximise a sheet, ideally panel widths are kept to 610mm - see predicament here:


Im just playing around with options here, i know the ideal thing is to leave the box as designed.

The central version changes the horn geometry and i am imagining therefore is unsuitable, however im wondering what the real life effect would be of the right hand option? A loss of low frequency response might be ok, as the subs will pick up the low end.

To make material efficiency gains, the the cab (therefore, horn) is 160mm shorter. If i build with solid wood corner details i was thinking i could extend the cabinets without needing more sheet material by 36mm more. in which case, horn would be 124mm shorter than design.

another option i thought might be to extend the horn with an added volume on the front:







but i guess if theres nothing on the other side for reflection then this is a bit futile. and fragile.

this is a potential end goal setup, with dual 15 ppsl subs, there is an amateur rambling thread on that somewhere else



any thoughts appreciated

Hey I’m looking to build a Di box to use for the 1/4 inch line out to covert to XLR

so that I may plug into my poweramp for my cabinet

Im looking for a transformer for it

any sugguestions ?

SOLD

Krell reference amp schematic could not find any information

Hello, iam looking for a friend. He have a cd player " ALTIS AUDIO CENTAURI ".
Inside is there should be a Philips CDM 12 industrial transport refer to all infos what i found.
As the unit is very old we want to replace the drive with the Philips CD Pro 2 MF - VAU1254/31LF (Cd Pro 804 C)
All that infos are the stickers and printed on the drive what we bought some years ago.

It can be swapped with the original drive with not much work-just a cover on the mechanical side.
So my questions are:
1)
As the new unit have a splitted analog and digital ground and the original not,
i want to know the pinning of the connection for power on the old industrial drive.
Every info is welcome, best of coarse are schematics, service manuals and more.

2)
Confusing is that the "user manual Premium 10501 " from the Philips CD Pro 2 MF - VAU1254/31LF (Cd Pro 804 C )
tells that the A/D grounds ar not connected on the PCB, but in reality they are. They PCB ground is connected over the mechanical metall chassis.
So i also search here for a real electrical schematic for the PCB.

The player is extremly seldom and have a seperate power supply and the company is not existend anymore as the owner passed away in the year 2002..
Iam a very skilled electronical/mechanical, but its stupid to start that kind of work with not enough knowledge infos.

So please, every help is sensefull and very welcome here.

Thanks Robert

Hi Everyone,

Picked up an old & very dirty Pioneer SA-7500ii showing signs of past mishaps. The original output transistors 2SB618A & 2SD588A are present on one channel, but on the other channel they have been replaced with SC2579 & SA1104, with a hole drilled in the heatsink to mount them. From the filth & dust build-up it must have been done a long time ago. Also one of the emitter resistors is is not original & the board is quite severely charred beneath this resistor, so probably from the time of the original failure.

Has anyone ever heard of these transistors being used as a sub for 2SB618A & 2SD588A and should they be OK ? On paper the specs look ok & to be fair the amp seems to work ok. Should I just leave them in or replace all 4 transistors with new ones ?

I know on various forums other replacements transistors are proposed, but to be honest most are not easily available at a reasonal cost. I can quite easily get 2SC3858 & 2SA1494 though. Any advice welcome.

Hi,

Always thankful for everyone's time and interest. I have received a part that I'm not sure is genuine. Can a part that tests as Darlington with Rshunt and w/ Protection Diode features be used in place of a standard TO-3 device? In my application - class AB power amp, where only the PNP's are Darlington - I think not, because the Vbe is double on the Darlington devices, so class AB signal switching won't line up properly.

I am repairing a Pioneer SX-1250, which has been blowing the main 12A fuse on startup. After testing the output devices, one bank of TO-3's has been found completely shorted. There are 4x total TO-3 devices per side: Parallel pairs. Neither side appears original. The good side has been tested with sig/scope and music, by disconnecting the power supply and driver board for the bad side. As it stands now, the working good side has 2SD555 and 2SB600 pairs (NPN and PNP, respectively), while the blown side has NTE87 and NTE88.

I have purchased 5 pairs of 2SD555 and 2SB600 parts from a vendor on eBay. The 2SB600's are the ones that test as Darlingtons, and so these are the one's I suspect to be questionable, as the datasheet for this part does not show either a Darlington schematic or mention of this arrangement. Tonight I pulled the known, good 2SB600's from the working side and they tested as standard ~.602 Vbe.

Equipment used for testing: Peak Atlas DCA75.

*Since we're on the shared topic of transistor matching, can I get a quick confirmation that Beta/Hfe testing is of primary importance when matching individual/solo (stereo) pairs of preamp/power devices, and Vbe testing is primarily important when matching parallel pairs? Thanks.

I have purchased the Elsinore waveguide, the most recent one for a centre speaker I am designing with a hypex amp. I would like to know a little more about the waveguide especially as it's not common in size, shape or width for that matter, not matching my 4 inch woofer diameter that it will crossover to. (They usually say the waveguide needs to match the diameter of the crossing woofer)

What is the lowest crossover point I can use which will still ensure controlled directivity to my matching Scaspeak 12W/8524G00?

And the waveguide is not like any other it's slightly deep but not wide. What are the tradeoffs of this kind of waveguide and what is the design principal behind it?

What is interesting is I know that the crossover recommendation for this waveguide is somewhat of a higher point of around 3000 hz but as the waveguide is larger in size I have a C-C distance issue so on paper at least I would like to go lower.

I am trying to place a printed text on a front panel in Front Panel Express. I select Insert|Text Engraving and in the dialog box select "Always print this element". But I keep getting an error message: "Error, printing on this material is not possible. Please select a printable material or choose another option for engraving mode".
I tried selecting different materials, alu, perspex, with/without coating, for the panel but the error stays.
What am I doing wrong?

Jan

As part of a project that involves a complete makeover of a Fons CQ30 turntable, I want to rebuild the power supply. The components are all ancient and the shape of the PCB is odd. No doubt this is due to its place in the turntable's enclosure, but i want to move it to a separate box. The elco on mine is most certainly dead.

As a noob (both to this forum and to diy audio) I wouldn't be able to do so if it weren't for the enclosed schematic I found over at Vinyl Engine. So a thank you to them.

Before I embark on making a new pcb from this schematic, I want to ask the open question: can any of the folks here with turntable expertise recommend straightforward ways for improving on the design of this power supply or the choice of components? (Without starting over with a blank piece of paper.) Anything that can improve the stability of the speed control for example. And I haven't checked but at least some of what is listed here must be obsolete.

The only choices I have made are the easy ones: a rotary selection switch for the speed selection, and new (rotary) potentiometers for the pitch adjustment. I plan to replace the motor with a NOS unit from a Philips GA312 I ran into recently, as mine requires some manual help to start spinning. Apparently these are are a drop-in replacement for the CQ30's motor (unlike the Philips GA212's motor, which are easier to find but makes the platter spin at around 150RPM without adjustments).

All advice would be much appreciated.

Slate & acryl DD tt

Hi folks, my first serious post here, hope you'll enjoy.

It began with a Dual 701 DD turntable, a nice turntable, but with an arm that is not up to the specs I wanted. The automatics were malfunctioning, so I slaughtered the tt and bought an acrylic platter from Diy Hifi Supply.



I was thinking about the plint, should I make a aluminium-ply-mdf-ply-aluminium sandwich like this:?




..or go for something different?




I went for something different, and since then I have done a lot of thinking, and a little work:



The acrylic platter on top of the slate plint illuminated by the midnight sun

Last easter i got a hole in the slate so that the EDS1000 motor would fit in.




Before that I had installed the power supply and speed selector / pitch control in a box:




The turntable with the motor and platter installed:




..and with a couple of arm boards temporarily placed on top:




I nice member of this forum saw the picture above on a Norwegian forum, and offered to make a couple of acrylic arm boards for me:




For this turntable the arm(s) have to be DIY as well, I am going for a Ladegaard tangential on the left arm board, and a 12" Schröder copy on the right arm board.

But I do not have enough patience to wait for the arms to be finished, so one of my temporar arm boards have to do as a base for my SME 3009/S2 Impr. for so long.




Not willing to make holes in the stone for the arm screen under the base, I had to do a little modification to the arm:




The left arm board is mounted to the stone with brass standoff/legs:




The right one is only standing on its legs, but they are shinyer than the other ones:




And of course there's something that simply does not fit in, and therefore has to go:




I am thinking about a motor cover made of black transparent acryl to replace this wooden thing.

The turntable plays with a Shure M75ED 2 with a Jico SAS needle to plow the grooves, and sounds really promishing.

Kind regards
Trond Kjetil

SOLD to close

SOLD TO CLOSE

Hi,

I'm trying to work out the budget for speaker units for the BH amp I'm planning on building.

Thinking of a Woofer + Midrange + Tweeter. How does one go about sizing the wattage specs for the these units. Any specific ones that someone can recommend would be a good starting point for me.

Will build the cabinets from scratch.

Thanks

Earl Josh

I took an old Radio Shack CS-5, gutted the old Linaeum tweeter, and substituted the GRS 2522. (The old tweeter was not working well and I could not fix it.) I chose the CS-5 because I had existing RS LX-5 speakers, and thought it might make a good tonal match, but time does not seem to be kind to the Linaeum tweeters. The GRS 2522 looked like it might be a reasonable substitute, so I decided to give it a try.

I tested with REW (generating white noise) in a non-ideal location (speaker propped on other stuff, and near a wall and corner), and got the below result. Except for the dip at 8k, this is better than I expected. I managed to guesstimate the match with the woofer pretty well, and it's eerily flat through the important midrange.

Woofer and tweeter use 1st order crossovers, which seems like it could be problematic, but it matches up OK, based on this. I estimate the woofer crossover to be starting at about 1500Hz, and the tweeter at 4k, so there's a lot of overlap.

I need to do a more complete write-up, but thought in the meantime, someone might find this interesting and/or tell me what my 8k dip is from. I did add a series 2.2 ohm resistor to try to match levels, so it's possible that it brought the higher treble down more than lower treble, I suppose.



(Edit: fixed attachment)

Hi, i need some manganin enameled 0.1 mm wire ~60ohm/m to build some resistors.
Please PM if any has some spare .

Best regards!

I'm in a need for multiple pcs/pairs of 2SK369-BL. Used are also fine..
Offers in PM.


Thanks!

As reported here: https://www.diyaudio.com/community/...-platform-feedback-wanted.380360/post-6884637

Hi to u all ,
a long time ago peter walker and mike albiston patented the current dumping circuit in which a powerful class b amp took over from a little linear class amp to provide the muscle drive needed by hungry lodspeakers through a wheatstone bridge.I would like to know if that topology has been used by other manufacturers and if so,what are its advantages and disadvantages compared to other conventional circuits?thanks.

Hi,
I'm interested in building my first single driver speakers but don't know enough yet to try an original design of my own.

The Jordan JX92s driver seems to be well respected and I like the wide baffle esthetics of the VTL. But from reading this forum, it seems like the GM MLTL-31 may sound better.

I notice that the CSA of the VTL and the GM MLTLs are almost identical. So my question is: can I use the cabinet volume and a port with same length from the MLTL-31, with the cabinet width and depth of the VTL and expect good results?

Also, how critical is the vertical placement of the driver? I like the look of the high driver placement of the VTL.

Thanks so much for such an interesting forum!

Wally

FS: Eminence Delta-15LFA Woofers (2) - $160 + split shipping

As close to new as you can get. Mounted in my folded OB speakers for a couple days, then pulled out. Powered with 45 SET amps, so not stressed in the least. They are backordered at PE:

Eminence Delta-15LFA 15" Low Frequency Driver

Will ship in the same packaging they came to me from PE in. I'll split actual shiping cost with the buyer. Look new, but I can get you pics if needed (they are boxed up). Thanks.

Looking for an MN1400PA, used in a number of Technics turntables.

I'm trying to sort out a Start/Stop problem in a turntable (see here) and want to try swapping out TR12, a 2SC1318. Any thoughts on whether a KSC2383 would be adequate in this location?

hello all!

i have a problem with a steg 310.2, it was working but it had the usual problem on the potentiometer wich made noise in the output, and unbalanced volumes in output..

so i desoldered it, cleaned and resoldered, after 5 minutes it goes in protection..
i checked the mosfets and teh Q64 was burn!, checked them all and replaced all the 6 mosfets on that side from the IRF540a with FQP33N10 as mentioned in the service manual..

but after 5 minutes of play i got protection again: this time was the Q63, replaced that one only, and after 5 minutes of music not at full volume same thing, q63 burn..

can it be a defective gain potentiometer the cause??

excepting from the unbalanced output it worked great form months!

I got Jolida JD302B recently. The amplifier is EL34 PP with ultra linear. I would like to modify it as triode connection.



I got this schematic and



I was told to cut the connection to the pin #4 and put 100 ohm resistor between pin #3 and pin #4.

Then, I found another schematic about triode mod.



This one tells that I need to cut the connection to pin #3 which is connected to the plate of a tube. And it also shows the disconnection from the output transformer to C2.

I am confused now. Which one is right?

1) cut the connection to pin 3 and put 100 ohm resistor between 3 and 4.

2) cut the connection to pin 4 and put 100 ohm resistor between 3 and 4. additionally, cut the connection between the output transformer and C2.

I don't have much knowledge in circuit theory.

SOLD

I have noticed a lot of threads about repairing older units and advice about not paying too much for them because they might need recapping either right away or soon.

My amp (Sony TA-F450ESD) is from about 1980. It sounds fine to me but I can't say my ears are in top shape so was wondering..............
What would be the noticeable signals that would indicate it is time to reach for the soldering iron?

I love transformer coupled audio circuits. But I have some transformers kicking around my parts box that need to find a new home.

• $45 Pair: Altec/Peerless 15356 Octal base. Look old, sound great. Some solder on the pins.
• $35 Pair: Jensen JT-11-HFMPC Tested but never used.
• $40 Pair: Sowter type 3128. Short leads, pulled from a circuit board. Screw mount
• $45 Pair: Sowter 9809f. Original length leads.
• $20 Pair: Onetics microphone transformers. 1:1 has center tap (I think) Jensen shown for scale.

$150 takes the lot. And I'll throw in some no name mic transformers.
$5 shipping each pair to USA and territories. PayPal or Venmo payment preferred. Outside USA please esquire, I'll check prices.
All working, just been sitting in the parts bin doing nothing for years. Put them in your projects and make them sing again!

Hi,

I am sure it is beginner's mistake, so please don't laugh.

I have a sony SACD (XB940), which ceased to play SACDs one day though CDs are still fine. So I thought the laser had drifted and got myself a new laser unit, but that was even worse (won't even play CDs).

Then I digged up the service manual. Apparently the servos of the laser unit have auto-tune. And once should do that with a Sony reference disc HLX-501 (or 503, 504, 505).

Without that on hand, I tried with an ordinary SACD just in the hope that it would also work. And of course wishful thinking.

The reference disc is next to impossible to get and cost a fortune. I wonder if anyone can help / advice.

(PS I already had a look at the other thread for the Sony CD reference disc, but the reference number for the SACD is different.)


Many thanks in advance,
Patrick

I have a Frankenstein version of the venerable Eico ST70, modified with no preamp section so it only operates as a basic power amplifier.

Gain is silly high - especially with a Audio Research SP-8 preamp. Short of rebuilding with a H-K Citation V circuit, what input tube would you use to replace the 12AX7?

See here for the 12AX7/6SN7/5881 circuit
http://tronola.com/html/st-70_mods.html

I’m looking to purchase 8 of each 2SK3497 and 2SJ618 MOSFETs. I do not need them matched. They must be real and not the fake ones available on eBay. I’m willing to pay a premium. I’m located in Illinois United States. Please PM me your offer. I’m also looking for information on what equivalent parts could be substituted? If anyone has any information, it would be greatly appreciated. Thank you all in advance.

As an opportunity to learn a bit more about amplifiers and particularly transistors, I've bought a Lecson AP2 Power Amp that has a circuit board that's been burned by overheating components - the centre of the board is all but trashed. I'm designing a new circuit board with as far as possible, the components, the layout and tracks being identical to the original. According to the schematic (not the one in the AC1/AP1 Service Manual the 'other one') there are a few resistor changes that distinguish the AP1 from the AP2, but even that schematic is a little different from the manufactured item.

Does anybody have a high def image of the AP1 that would enable the resistor values to be identified? I'm interested to see if my new boards would enable the repair of an AP1. The tantalum capacitors at the front end on mine are 15 microfarad not 22 microfarad. I wonder how many versions of the AP1 & AP2 were produced?

Attached are images of my 'good' board and the top silkscreen of my prototype replacement. I believe somebody had previously replaced two 0R27 wirewound resistors with that pole of grey resistors

About 10 years ago for a short time this site was set to display random polls from current threads, on the home page. As a curiosity, these have been harvested from the wayback machine.

-----
What's your next project?
Source - 7.47% 18 Votes
Preamp - 20.75% 50 Votes
Amplifier - 42.32% 102 Votes
Loudspeaker - 24.90% 60 Votes
Other - 4.56% 11 Votes
-----
Do You Think Single-Ended Class-A Amplifiers Sound Best?
YES! - 40.45% 108 Votes
NO! - 19.10% 51 Votes
Nothing Special. Just Another Amplifier. - 22.10% 59 Votes
I Haven't Seen Such An Amplifier. - 18.35%
-----
Cat or Dog, Tubes or Sand?
Tubes + Cat - 23.81% 35 Votes
Tubes + Dog - 18.37% 27 Votes
Sand + Cat - 27.89% 41 Votes
Sand + Dog - 18.37% 27 Votes
Other (be nice to us and tell) - 11.56% 17 Votes
-----
Have i lost it or is it good?
You've got it totally wrong - 50.00% 2 Votes
You're overlooking other important things so it'd have no effect - 50.00% 2 Votes
There is cleverness in it, but you're not quite there yet - 50.00% 2 Votes
All hail the messiah of audio fidelity! - 75.00%
-----
well, do MC carts sound better than MM ones?
yep - 70.77% 46 Votes
nope - 29.23% 19 Votes
-----
Most neutral/least audible crossover topology?
B3 - 15.38% 2 Votes
LR4 - 7.69% 1 Vote
B5 - 0% 0 Votes
LR6 - 0% 0 Votes
B7 - 0% 0 Votes
LR8 - 0% 0 Votes
LR2 - 23.08% 3 Votes
none of the above - 53.85%
-----
Colour of the pcb
Red, white print and gold pads - 20.00% 4 Votes
Blue, white print and gold pads - 20.00% 4 Votes
Black, white print and gold pads - 30.00% 6 Votes
Black, yellow print and gold pads - 0% 0 Votes
Yellow, black print and gold pads - 0% 0 Votes
Green, white print and gold pads - 25.00% 5 Votes
White, black print and gold pads - 20.00% 4 Votes
White, red print and gold pads - 0% 0 Votes
-----
What's the highest frequency you can hear?
Up to 21kHz - 1.43% 1 Vote
Up to 20kHz - 0% 0 Votes
Up to 19kHz - 4.29% 3 Votes
Up to 18kHz - 17.14% 12 Votes
Up to 17kHz - 20.00% 14 Votes
Up to 16kHz - 22.86% 16 Votes
Up to 15kHz - 11.43% 8 Votes
Up to 14kHz - 12.86% 9 Votes
Up to 13kHz - 2.86% 2 Votes
Up to 12kHz - 7.14% 5 Votes
-----
Will MJL21193's crazy design work as proposed?
Yes - 49.30% 35 Votes
No - 8.45% 6 Votes
Maybe. - 29.58% 21 Votes
I'll laugh when it doesn't. - 12.68%
-----
What cabinet should jlux use?
Del Sol -Aura NS3 design - 5.26% 1 Vote
Milli Fonken - 10.53% 2 Votes
RS100 Transmission design - 26.32% 5 Votes
HEY- The best choice is none of these!!! - 57.89% 11 Votes
-----
To Glue or not to Glue, that is the question.
1 - Glue the covers on at the Factory. - 0% 0 Votes
2 - Leave loose, let end users choose to use or discard cover. - 87.50% 35 Votes
3 - Offer both glued and loose cover options. - 12.50% 5 Votes

Hi all. Tube neophyte here with a potentially stupid question. Please bear with me.

I already own a tube preamp which is currently feeding a solid state amplifier. I am interested in adding a <5 watt valve amplifier to my listening room. I see many of the designs I'm looking at have tubes on the input stage like a 12ax7 or 6j1, as well as their output stage tubes. Is this going to be redundant or unnecessary since I already have the tube preamp? Should I just be looking for plans to build a model that is valve output only, to simplify the design and reduce cost? Is a tube input signal chain "too many" tubes?

Thanks for your patience.

We've all been told an EBP fifty and lower is the more "suitable" choice as sealed for your favorite woofer...but when I model out these drivers in a BR alignment, the graphing has said drivers reaching way deep as to easily pass thru 20 hertz flat as a pancake. So what are those "tragic" consequences of this :unsuited" driver in this alignment.?

EG...GRS RSRMO-8

125W
90 Db
2.25 " VC
fs 22 Hz
Re 7.2
Le 1.82 mH
Qms 4.94
Qes 0.63
Qts 0.56
Vas 342.35 L
X 2.5 mm


----------------------------------------------------------------------------------------------------------------------------------------------Rick....................................

Hi
I'm Alessandro from Italy
My english is not very good.
This is my first synergy project. I've planned it for many months reading almost every threads about MEH on the web especially on diyaudio so I deciced to subcribe here and say BIG THANK YOU for the immense knowledge and passion
without being hungry when different opinions are involved
(italian forums are diametrically opposite, my bad).

My idea was initially to replace 2x MACKIE SA1521 (133db max and 46kg) with
something with same or higher spl and less weight and max same dimensions to fit on a wagon car.
Immediatly I've found BFM DR series, good sensitivity but not high power handling.
When I've seen first Synergy pictures and threads I felt in love 😱
In the same time the Peter Morris PM90 i think are no brainer for quality, dispersion, high output, dimension and weight.

So I decided to design a 80x50 Synergy with:
2x rcf mb12n351
1x b&c dcx464
YES the same drivers suitable for PM90.
So if my synergy attemp is crap I will make pm90.
Tomorrow 😀 maybe the drivers will arrive from TLHP-france.
I have a diy steel 900mmx450mmx170mm so I would use for this project.

Meanwhile I have some questions:

1-80x50 coverage is good for me because I can implement 2x12 in 600Wx350Hx430DEPTH and horizontal pattern control is 300hz according to Bwalso speadsheet v5 (immense thank you) but is unual for a synergy, however is exactly 1.6 ratio.

2- with coax CD I can cover mids without cones and mid ports location "problem" so can I move 12"s a little far away from CD?

3-I want to extend frequecy to 100-110hz to use with subs. My hornresp AP-AP1 parameter selections are correct simulating reflex ports inside the horn?

4- on diyaudio DCX464 I read throat exit angle of this driver is 0°. I've tried to design on Fusion 360 (loft function) a round to rectangle using 80x50 angles to smooth CD throat. Can I have problem with distortion? Can I do it better maybe with first segment at 0°?

In Attached Hornresp 4pi simulations, Designs on Fusion without secondary flare.
Thank you very much
Ale
View attachment 956830

View attachment 956831

View attachment 956832

View attachment 956833

View attachment 956834

View attachment 956835

View attachment 956836

FS:

One pair of Hashimoto 20-3.5U Output transformers
3.5K into 16/8/4 ohm
Asking 450€/pair
Will ship worldwide

Here's a simple circuit I've been playing with for a balanced input MC pre. I'll do a bit more work on it in the coming few weeks. Its a pretty low cost approach - the most expensive item being a decent dual opamp like the OPA1642 for example. The noise will improve with higher collector currents, but a practical limit would be about 6-8 mA per side - any higher than this and the 5-8V reg will probably need a series pass device.

Note carefully the comments about resistor matching for R1-R4 - the CMRR depends on it!

U1 servos out any DC voltage difference across the emitters of Q1 and Q2 to ensure DC current through the cartridge is minimized. In practice, an OPA2188/9 would be used for this function (I just used the AD745 because this is what was in the LTspice library) as I have done in the X-Altra MC/MM RIAA (that is an unbalanced input, but lower noise). The other half of the servo can be used for the 5-8V reg - the PSRR of these devices is superb, so they work well in low noise servo and low noise regulator functions.

Update 02 January 2022 - I have added the PRELIMINARY 1st cut measurements - see PDF file below

I am tweaking an F5 Amp and using IXFN 180 n10 and IXTN 170 p10p power MOSFET's.

http://ixdev.ixys.com/DataSheet/98546.pdf

The channel resistance of these is less than 0.012 ohms - that's not a typo.

Have lowered the current detecting resistors R11 and R12 to 0.1 ohm
and changed resistors controlling the current limiting bi polar transistor appropriately.

Have prototyped these MOSFET's in Aleph style amps and the F5 biased at 0.4 amps.
The sound is jaw dropping.


However, these power MOSFET's have 10 times the transconductance of the
power MOSFET's spec'ed for the F5.

Because the transconductance is 10 times, I am concerned about thermal run away,
and do not want to be a member of FAB (N.P. refers to them as Fearless Audio Builders).


So, I either lower the voltage gain of the first stage, or increase the Feedback.

any recommendations ?


Thanks,

What are the choices now in 2021/22 for a stepped attenuator with a remote control? I want to add one to a type 47 preamp, so around 100K.

I know about Khozmo, but I'm sure there are many more of different types and at different price points.

Experiences and suggestions please?

I have a pair of 1 + 1s with Red Medallion transformers that were given to me. They sat for a few years unused. I just got a new turntable and cartridge and did some serious listening and noticed something wasn't right. The left and right channel balance didn't sound right while sitting down and listening near field. After listening in mono and up close to each panel, I noticed the right channel lower panel has a reduction of treble, and the left channel upper panel also has a reduction of treble. I switched the transformers and get the same issue, so it appears the panels are the problem. I looked at the wires from the panels and the connections to the speaker wire spades and HV pin to the circuit board look good on both speakers. Listening further away in my usual location still sounds amazing.
What could cause this? Has the output wire from the high frequency transformer come loose from the panel? If so, is there a way to fix this?
Any other possibilities?

Hey guys, i'm preparing to build a ribbon microphone and i've decided on winding my own transformer.

I've done the math and come up with the appropriate wire gauges and turn counts, and i will be using a smallish iron powder toroidal core, but i was wondering if anyone potentially has more knowledge when it comes to audio transformer construction. My biggest question currently has to do with the "layout" of the windings, more specifically, should the primary and secondary windings be wound into each other, or separated along the circumference of the toroid? i'll attach an iffy paint drawing to illustrate what i mean if it's unclear 🙂

(also another thing, but does the orientation of the windings in relation to each other, i.e. if one's would Clockwise and the other counter-clockwise?)

Thinking about something cheap(ish) and easy for a domestic corner horn. Any thought on using a little full-ranger in a big horn?
These drivers below look like they might do OK. I would cross to a woofer at about 500Hz or as low as the 2" will play.

I just want some opinions if this is worth pursuing. Thanks.

Tang Band W2-2243S
https://www.parts-express.com/pedocs/specs/264-803--tang-band-w2-2243s-spec-sheet.pdf
Tang band W2-852SH
https://www.parts-express.com/pedocs/specs/264-808--tang-band-w2-852sh-spec-sheet.pdf
2" Throat Horn Bolt-On 18"x10"For Assorted Bolt On 2"Exit Drivers 90°x 40°
https://www.ebay.com/itm/231420420855?hash=item35e1bb62f7:g:E6gAAOSwhglTxvJm

Hello!

Long time lurker here. Although I've built a few kits I'd like to build my own now. With the kits I did they all had one similar design characteristic, they all fit in boxes. I procured a unique hubcap to an aircraft. Specifically a 707. I had intentions of turning it into a clock but didn't like the idea hanging a 5lb weight from a wall, lol. The material is cast aluminum and can be brazed. The difficulty here is finding something that'll fit inside of it. It's 8" diameter x 4" deep. Flat bottom and relatively flat top with the exception of the branding "Boeing" across the top that is cast into it. I don't mind drilling holes but would like to keep it to a minimum. Ideally I would like to have the in and out connections on the sides but the question is the volume knob, it's going on a desk so putting it on the top would be kind of weird but with the curvature of the sides and the larger diameter knob I'm afraid it won't sit as flush.

Does anyone have a build that'll fit such a size case with minimal through holes (which I realize is a big ask with tubes) but this is intended to be a gift to the guy that got me interested in tube amps 20 years ago.

Thank you for any help you may provide

Since this DAC inverts polarity, Is it best to switch polarity at the speaker terminals?

Is this NOS DAC the same as the Denafrips, R2R, BYOB, etc NOS DACs commercially available now?

Good Evening,

I have a LM1875 running single supply on a 24V SMPS which seems to be hitting the rails and clipping at about 17v (peak to peak) using a 400hz sine wave.

The chip is receiving 21.4v after regulation (LM317t) and while under load. How close can you get to the rails before distortion is expected?



Even with it biased at 10v, i thought it should get 20v without clipping. Is there anything i could be missing to cause this?

I would also assume that getting an output of 6v RMS on a 8ohm load would be pulling roughly 750ma, but it seems to be much lower.



Any help would be gratefully appreciated 🙂

Hi,
I have problem with this amplifier. It has some buzz on output.
First i thought that changing preamp 35V capacitors and adding 6800uf to main filter capacitior will help. But not significant. Maybe little hard to say.
Amplifier has preout-main in rca plugs and switch for interstage preamp connection. Amplifier has buzz when i switch it to internal preamp. But NO hum when i switch internal preamp off. If i connect another preamp to main in it buzz again. If i disconnect cables again NO hum. But when i plug bridge rca plug into Main in socket ( i made rca plugs with signal and gnd connected) it start to BUZZ again. Strange in the past power amplifier can do some buzz with rca plugs opened. But when i bridge them it was silent. Here is oposite. Amplifier BUZZ when has bridged signal and gnd pins or connected preamp (internal or external). Internal preamp don*t make buzz if i connect it to external power amp.