I have many Motronix MRF-400H mosfet amplifiers (Approx 30pcs!) in stock (Barely used).
a few of them with Nichicon caps installed, all of them are in perfect working condition.

Price for matched pair: 30$ (BNIB on eBay 40$+15$ shipping for each!)
Worldwide shipping: 12$. (4 pairs or more, free shipping!)
Paypal fees on me 🙂


Specifications:
RMS continuous power:
150 Watts driven into a 4Ω load (tested with 2X40V DC Power Supply)
85 Watts driven into a 8Ω load (tested with 2X40V DC Power Supply)
0.03% Total Harmonic Distortion (THD+N)
Load: 4-8Ω (*** Can work with 2Ω load when use 2X30V DC Power supply)
Signal-to-Noise Ratio: >100dB A-weighted
Frequency Response: 20Hz to 20kHz ±0.5dB
Bandwidth: 20Hz to 100kHz ±3dB
Damping Factor: >200 @ 4Ω
Slew Rate: 30 Volts/ ms
IM Distortion: <0.05% (IHF)
Input Impedance: 20k ohm

After building a set of Pensils a few years ago I fancy trying my drivers in another enclosure.
Does anyone have a plan I can follow?

Thanks

Cleaning out my project bins and have the following unpopulated/bare boards for sale:

1. (2) MyRef RevC monoblock boards. These are the v1.3 boards that I ordered from Siva (linuxguru). See the pics in the following post: https://www.diyaudio.com/forums/chip-amps/167458-myrefc-build-guide-post2844341.html. I will include copies of the schematic and board layout that I received with the kit. $15+shipping for the pair.

2. An early (2008) VSPS (Very Simple Phono Stage) board from RJM. See the following thread for more info: https://www.diyaudio.com/forums/analogue-source/33555-diy-phono-preamp-cheap-simple.html. I will include a copy of the original BOM. $5+shipping.

PM me if you have questions. Thanks!

-bill

This is my first working tube amp. I pulled it from a old readers digest portable record player. I built a dim bulb tester and recapped it before hooking it up to my pioneer bs22 speakers. Wow am i impressed!!
Anyway...now what? Id love to remove the tone controls. And maybe improve the circuit somehow. But, i also want to keep it simple...
Thanks in advance

Amp powers up but no output .

I was checking for regulated voltages and on 1 opamp I bet the following voltages

NJM4556

Pin 1:21.35
Pin 2:12.79
Pin 3:12.79
Pin 4:12.62
Pin 5:0.02
Pin 6:12.64
Pin 7:12.78
Pin 8:12.78
Pin 9:21.53

Is this normal for these amps?

Hi!

Just for fun, a small test of three DAC's.

Denon DCD 1290
DCX2496, rca modded
OpenDRC-DA8

Source: CD 16/44.1 original record with a crowdy mix.
Target: Motu Ultralite ~600$ sound card (24/44.1 capture)

I will share the labels of the tracks tomorrow.
...Can not upload atm.

While rummaging through my wood pile, I ran into some zebra wood scraps that I thought might look cool around my AT-LP120XUSB. Spruces it up a bit. 🙂

For now they're just tacked in place on three sides with some hot glue. I plan to dampen the underside of the plinth with Plasticine sometime....when I do that I'll trim them up and fit them a little better, and re-fasten them a bit more securely, tho I'm not sure I want to mount them permanently yet.

As stated I purchased the ebay kit as seen on them here and there with the new PC boards and the like. So, Have only recapped the Hafler DH110 with success I then though to take this on. Long story short. I felt pretty good about my soldering job on it with no cold solders that I am aware of. It power on with a variac and have it up to 110. No fuses blown. Great. Get speakers on it and nothing. Not even fuzz sound. Wiggle the rca's and no sounds as well as speaker wires to hear that cracking sound when you hook them up. Just nothing. So, not knowing how to back track diag. Could someone walk my through what to check first and then the next to see what I hooked up wrong. Was working on old board and wires before.

Just to have full info.. I also rewired the entire amp as well and thought I followed the instructions to the letter.

Can get pics up if needed. Thank you for any help to this noob trying to be a one of this idiots to take these things on.

I do have a Fluke Multimeter if I could also know what setting to be on to check different parts of the amp out to diag my issue.

Geez, what a noob...

Does anyone have a frequency response plot for the KEF T27 tweeter? The only plot I can find online includes a third order high
pass filter, but I want the response of the raw driver.

Has anyone 2pcs of the LTC6228IS6#TRMPBF and would like to sell me them?
Currently ordering parts for a new project and that are the only two parts I can't get...

National Instrument has made a "community edition" of LabVIEW 2020 available for free. You need to create an account (of course) and redo the license after a year; it's a fully functional "test and measurement" program development environment that works with GPIB, Serial and other USB connected hardware. Pretty good.

Regarding Audio test, there's not much you'll be able to do with it that hasnt been thought of and done already - considering the myriad of available audio test programs available in the last 20 years...

What you can do with it is create something specific to a particular need, that other general test system programmers wouldnt have possibly thought of -

Something like "When I clap my hands, give me a spectrum analysis of the sound I'm measuring in the moment just before the clap".

I'd be interested if anyone here installs and uses the LabVIEW "community edition" for audio test and measurement -

Hello. I Thought in a project at the begining of this year with SB Acoustic drivers. I wanted a 3 way floorstander with the following config:

Tweeter: SB29SDAC-C000-4
Midrange: SATORI MW16P-8
Woofer: SATORI WO24P-8

I thought in a active system although I have changed my mind and would go for passive... or selling the drivers because I do not have much time not space for this nice project.

Does any one of you has any suitable crossover suggestion for this config?

Thank you

I have a Behringer nu6000dsp that gives a hellacious power-off thump when switched off by my smart power strip.

I want to use a relay at the speaker outputs that will open before the power is removed, which I can achieve with the delayed output on a surge protector I have.

I've perused many threads on relays and it sounds like mechanical ones are problematic because I'll never be switching with a load to keep the contacts cleans.

The possible issue with a SS relay is linearity at low levels.

I'm thinking it's probably not an issue with subwoofer frequencies but wanted to check with the more knowledgeable.

Would this one be suitable?

Solid State Relay 25A | RSS Solid State | Solid State Relays | Relays & Timers | USA

Key Features
Current ratings up to 90A at 660VAC
AC (90-280V) or DC (4-32V) input
Input current regulated 10mA
Photo isolation of input and output (up to 4000V)
Zero voltage turn on
Dual SCR output with built-in snubber
Optional fingersafe cover
Worldwide approvals: UL
C-UL
TUV
CE
LED status indicator standard
Updated pressure plate for easier installation of wires
New housing design keeps wires from twisting and breaking
Dual SCR output with epoxy free design

I bought these supposedly 30v zener diodes.could anyone confirm that they are as such?Never saw such notation.


PS.They are indeed...just measured them, but i couldn't find a 40v supply at hand before writing this topic..As i can't delete it anymore...

hi,
i have this Parmeko oil-filled transformer,
and i dont understand the primary windings description?
it's quite clear the secondaries are 200-150-0-150-200
but the primary is a bit confusing 0.5.90.115 ???
how do i connect for 230vac operation?
and what does this 400c/s stand for?
please help me to understand it.
best and thank you.
K

I have acquired an amp which uses two ILP HY248 modules and a single ILP power supply.

When I turn it on I get ~10v across the outputs, but only if there is a load/speaker attached. If there is nothing attached there is no voltage and no voltage appears if a load/speaker is subsequently attached.

If, however, I start to put in a signal, one of the modules develops a DC voltage and one does not.

Any ideas how to fix this? Given that they are modules there is not much I can fiddle with. Can both be broken in the same way?

Many thanks,

Simon.

I just made a pair of XKi’s with PA130s in them. I am powering them with a Behringer iNuke1000dsp. I mounted them under the eaves of the side of my garage for some backyard sound and for movies when I bring a projector out. I watched a movie last night. Wow!!! I am so happy with these. The bottom is so beefy for the size of these!!! I’m not nearly as eloquent in my description but everything just sounds so well balanced. I did some tweaking with pink noise(though not really cuz I just used my iPhone mic) and a sine wave sweep.
Thank you so much to whoever has designed/shared plans!!

After much reading i have built Troels Gravesens Fusion BAD. (pic attached) Why, because he seems to go into every detail and explanation and builds for big companies as well and then gives out free build information. i liked that style.
I think they are great, i think he has done a great job and service, i am listening now, everyone else who has listened says how "out of the box" the sound is, its dynamic, realistic, great bass etc etc.
Its the best sound i have ever heard, but i accept completely there is better to be had, even Troels' own more advanced designs, probably much of what all you guys build.
I have also now read lots more since i built these.
I have done quite a lot to the room, that has helped a lot as well.
I am not dissatisfied at all, more curious, everyone says Open Baffle blow boxes away, so, if i used exactly the same hardware on an open baffle would it be interesting and good, or a waste of time and effort. the baffle could be the same dimensions, i can use the passive crossover i already built for mid/treble and even adjust the bass if necessary as the design has DSP plate amps on the bass....
It may just be that lockdown causes this curiosity, is it worth a project or a waste of time!?
thanks mike

This is more a thought experiment, I have built a couple of 3 way speakers with passive crossovers. I think about making them active, but I hit the same wall, price. For a 3.5 way setup I would need 8 channels of amplification. I think class D would work for me, but every option I look into, new power amps, kits, raw amp boards, Hypex plates or used multi-room amplifiers it always ends up costing $1,200.00 USD or more. Then I need to add a 2 in and 8 out DSP like the Aurora and I stop thinking and stick with my roughly $300.00 3 way passive crossovers. Am I missing something or is active still just expensive?

Hi
My ML Purity has stopped working, and I suspect that it is due to a
failure in the Class-D amp. (the panel works fine).
So, does anyone has a schematic for this Amp?
Br,
Brian

I have here a output transformer with ul taps and lots of 6v6 tubes.

I don't like 6v6 in a harmonica amp, too bright. but looking at building a guitar amp to use some of the parts I have on hand.

if anyone has tryed ul on the 6v6's push pull how did they sound.

preamp will probably be 5e5 but using Russian 6h9c

This is all just an idea @ the moment

I'm having trouble with my Sony CDP-333ESD which has a Sony BU-1 laser assembly.

I have just replaced the original BU1-E laser with a compatible second-hand used BU-1C.

The good news is that after installing the replacement laser it reads and plays around half of my CD's flawlessly from start to finish. The bad news is that with the rest it will not even read the TOC.

If I load a disc that it 'doesn't like' it will not even spin the disc which suggests to me that it is not detecting a reflective surface from the disc. Is that correct?

So does this mean that the photo detector system is somehow defective? Or could it be that the laser power is just a bit low (because of normal laser aging) and that this only manifests itself as an issue on discs with lower than average reflectivity?

It is very frustrating because it sounds great when playing discs it can read!

Looking for a FR driver that performs well between 100Hz - 20KHz in sealed or circular ported enclosures for LCRS speakers that will be crossed between 100-120Hz.

Goal - To use the advantage of the point source accuracy of the sound from a full range driver to build a 5.1 speaker set up for movies and music spanning genres like soft rock, dance and pop mainly. For the general sound quality benchmark, lets use the Marantz NR1510 AVR as a reference.

AVR Power Output - 8 ohm, THD - 0.08%, 2ch Drive - 50W

Current top contender - FaitalPRO 4FE35.
Reason - 8 ohms, 30W, 90Hz - 20KHz, 91dB, has good reviews and the amazing price of £13.73(Vat incl)/driver .

Question
Is a driver that has 100Hz - 20KHz range enough since HPF will be applied on LCRS speakers at 120Hz on the AVR or do I need a driver that goes lower?

Would appreciate other driver recommendations. Can go for higher priced drivers if I can get appreciably better sound quality.

PS: My earlier find was Tang Band W5-2143(£65/-) which I now feel is over kill for this project in term of its frequency range or should I stick to it for its sound quality.

This interesting article as well as recent discussions have made me think again about how I test the speakers that I am experimenting with, and also evaulating the entire sound reproduction system.

I do not have the sensitive instruments to test my speakers, no an anechoic chamber, but this may be beside the point. I have been, after all, listening to music and testing what I hear 'subjectively'.

I have come up with some working guidelines to evaluate audio systems by ear only:

• Frequency range - do I hear the lowest frequency and highest frequency instruments?
  
• Clarity - Can I hear all the instruments playing all the time clearly. If it is a familiar track, can I hear what I hear with headphones and do I hear any detail I had not heard before?
  
• Can I hear what seems to be distortion?
  
• Are the percussion sounds sharp and clearly defined or sort or muffled and woolly?
  
• Do I hear any unnatural (to me) colorations of sound- boxiness, sizzling sounds from the tweeters?
  
• Do the music and vocals sound natural?

There are only a few high powered systems and headphones that will pass fare well in the above set of tests, so it is kind of a basic hi fi filter.

Anything more to add? It seems a good way to do things.

Confusions about the options and possibilities how to combine the BPBP with the Maya remote control, made me decide to start this thread, where all info being scattered over several threads now combined in one place.

Intro
A preamp without a remote control, in particular for controlling the volume, is only half a preamp.
The BPBP is a superb preamp, with a solid circuit design, but most special is the absolute excellent PCB design that makes it stand op top what is possible today.
The circuit design itself was used almost exactly by Mark Levinson (and probably by many others also) over the last 10 years for all their models of Pre-amps, with the difference that they use Fet switches in a linear R-2R network for volume control, where the BPBP uses a standard linear Pot.
A pot can be remote controlled by using a motorized version, with added hardware, but more elegantly is to control the volume digitally.
Fet’s as being used by ML cannot compete with Relays in behaving like ideal switches and also a linear R-2R network is way more complex in # of components and in steering without having any advantage over a logarithmic attenuator, so the choice how to replace the pot was easy to make.

Realisation
In controlling those relays, a remote control is needed, and my attention was caught by the well-designed MAYA remote controller, having lots of options, like Bluetooth and a learning IR remote control, 64 steps to control the volume in 1dB steps, multi-channel select and last but not least a serious display giving lots of information.

A complete Maya system must be seen as a “passive” preamp where the signal comes in, gets attenuated passively via a logarithmic relay switched attenuator and leaves the system without any amplification in between.
As such, Maya is doing a great job.
The BPBP however is an active system with a very high CMRR and dynamic range, where volume control is integrated in the feedback of an Op-Amp.
As good as passive preamps may be, the top of the preamps is reserved for active preamps when looking at test magazines like for instance Stereophile.
An interesting feature is that hardly any high end preamp has a tone control, which is also not available on the BPBP.

There are however some potential restrictions like only having 2 input channels.
For this reason a 6 channel GB was started on this Forum.
Another restriction is, that the BPBP is in its basic form has no provision for a remote control.
To solve this problem, a Volume Control Board (VolCB)* was developed giving the possibility to have 64 steps of 1dB each, to being steered by the same Maya controller that also controls the passive Maya preamp.
And here it is where things are beginning to become complicated.
There are three different boards start with: the BPBP pre-amp, the Volume Control Board that replaces the stereo pot and the Maya controller.
This volume control board (VolCB) can select via the Maya remote control between the 2 channels that are available on the BPBP preamp.
If you wanted more channels at your disposal, there was the 6 channel GB board that is operated manually, but no longer available.
With a new GB PCB would it be possible to select 4 or maybe even 6 channels from a similar external input/output board directly from the existing Volume Control board, because the control hardware is already there.
If someone can give me all the essentials of the 6 input GB, I could make a redesign directly to be controlled from the VCB. Maybe 4 balanced inputs should be enough for most situations?
It would be also nice to add a balanced record output to this external board.

Do not confuse these multi-channel options with the multi-channel boards that Maya supplies for a complete system, because they cannot be used for the purpose of selecting input channels in combination with the BPBP.
In case you are happy with a passive preamp, I think the full Maya system will be an excellent choice with the option to have multiples of 4 input channels either Single Ended or Balanced.
When you want to go for the top in high end active preamps, take the BPBP.
However using the full Maya system with all its features like having many input channels IN FRONT of the BPBP, thus placing two preamps in cascade makes no sense at all and should not even be considered.

To conclude for Stereo Applications:

1) use either the full Maya system with expandable multi-channel inputs, or
2) The BPBP with standard 2 input channels to start with, combined with the Volume Control Board and the Maya controller subset, as in this diagram or (later)



3) The BPBP with an added multi-channel board (still to be designed) with 4 or 6 balanced input channels to choose from and also equipped with a balanced record output, again combined with the standard Volume Control Board and the Maya controller subset.


* Until now this board was called the “Hans” PCB, but I suggest changing this name from now on in VolCB.

Maybe all MP3 players ?
Is there a limit to the number of ( mp3 ) files that can be on 1 usb stick ?
Or number of bytes ? ... Or ?
I made a compilation of albums for my friend ,
and the titles ( at least some of them ) show on his screen ,
but the stick does not play .

I've seen some references to the idea that a bipole driver configuration can eliminate baffle step effects. I'm not seeing it.

Any driver putting out long-wavelength frequencies (compared to box dimensions) is going to radiate into 4*pi steradians. Put two drivers on the front of a box, and both are going to "creep" around in the lower frequencies and drive the whole hemisphere. Put one on the front and one on the back, and both are going to do the same thing.

Am I misunderstanding the argument or is it not grounded in reality? At the end of the day, it shouldn't matter where you place a driver if the wavelengths it is sourcing are large compared to the box (baffle) dimensions.

So you've built a diy amp, it tests ok with a restive dummy load but when you plug it into a test speaker it shows signs of instability, how do you personally go about testing and then making the amp stable?

So far I've only found two references online to the method, the best being this one by Patrick Turner - amplifier-frequency-tests I looked in the Tek Cookbook and in Metzler - nada. There is obviously some info in Radio Designers but for those who aren't big on theory it can be a bit opaque. After having read Patricks article there's a few things I'm unsure of but AFAIK the procedure is this.

With the amp in open loop and closed loop and with various capacitive loads do frequency sweeps looking for where THD is greater than 2% or where the OP of an amp peaks.

So for instance I ran several sweeps yesterday with my recent 807 PPP amp with a 100n and then a 470n as load, noting down where THD exceeded 2%, no peaks were noted or increase in THD.

I then ran a sweep with my big test speaker which is a cobbled together job of a 15" Celestion woofer cab, 10in Celestion in another cab, and two Fane horns in another cab, all through a Kef Xover, this typically is a difficult load. I got more clear results where THD shot up to 80% at 15hz and at 45khz and again at 111khz, this was using a HP3903B to monitor the OP as well as a B&K AC voltmeter, signal source an Advance Type 81A.

I'll run some more but would be very interested in other builders methods, I'm after practical methods rather than maths heavy methods involving bode plots, Nyquist diagrams and imaginary numbers please. I'll probably change the odd coupling cap and fit a few step networks as well as a zobel network to reduce gain at HF but interested in other members wrinkles.

Andy.

Hi everyone!

It seems that recently I made a major discovery for which, I think, I should be given a Nobel prize. 😉
What I did was I switched off an active crossover in the subwoofer amplifier and put a large and thick pillow near a woofer. Thus the woofer is used as a full range speaker without any crossover but the woofer in the sub is closed or muffled by a pillow and hence I hear only bass up to may be 100Hz. I was amazed by the quality of bass in this set up which does not cost anything.
You just need a good woofer, a cheap amplifier and a pillow or a blanket. And that is all: no crossover is required and a pillow is used instead of crossover. The bass is fast and pleasant to listen to. Isn’t that wonderful?

As regards the fact that some people might think that in this setup the sound coming from the sub can be easily localized that is not the case.
I have installed my sub near the right speaker to the right of the speaker. If 100 to 200 Hz were coming out of the sub then I could easily hear the sound coming from the right speaker. But I do not hear any sound coming from the right. All I hear is just deep bass.
So this means that a pillow muffles sound very efficiently indeed.
I wonder if anyone has heard of this method before?

Selling my stash of TDA1541A DAC chips

All tested in various diy projects

marking explainations here: Philips TDA1541A d/a converter information - DutchAudioClassics.nl

TDA1541A - S2 100 euro

The others 40 euro combined

Shipping at cost

Hello,

I am trundling right along with my Neurochrome LM3886DR amp build, and I am at the point where I need to start wiring things together.

(red and black wires sort of mock up the input signal path)



What is the prefered method of wiring single ended inputs to an amplifier board?

The two options are, Mogami 2330 shielded microphone cable or plain 'ole twisted solid core 22g wire.



Shielded is a little more difficult to wire up, but is "supposed" to be better. (don't be too critical of the ends on the wire in the photo, I was just playing around, I know the ferrule should be pushed up to the insulator of the centre wire)

Twisted 22g solid core wire is super easy to deal with for soldering and "stays put" when bent where it needs to go.

Like most things I do, I am sure I am overthinking this, and either solution would be fine as I have seen both examples used. I am also pretty sure I would not hear a difference, but I would like to use "best practice" even if I won't notice the difference.

Thoughts on one vs. the other?

(I did lots of reading on this forum about this topic as well as general Google searched and I am still on the fence)

Thank you,

David.

I am looking to venture more towards a 300B dual tube per channel integrated amp for its sound preference and lower plate voltage. This dream machine might weight a ton after its done but that's fine. If I can get some suggestions with a rock solid simple design circuit with an excellent set of transformers that would be great. Integrated amp is always my personal preference. A dual tube mono block can be a last option. I saved up a handful of preamp, rectifiers and 300b power tubes. Any takes or suggestions will help be great.

Hey guys,

I've recently thrown a KAB-BE battery board onto my build with KAB-250v3, although since it's run out of power I haven't had any luck charging it.

It recommends a 19V 1.5A power supply to charge it, the closest thing I could find is a 1.66A. Regardless, Ive tried to charg overnight and I still don't have any power.

Any ideas what could be wrong?

My only hypothesis is that you're meant to connect a charging cable directly to the battery, although the only wiring setup I could find similar to mine had power go into the amp.

Thank you!

Why do my active speakers sound better with my PC as a source compared to a Denon AVR-E300?

PC motherboard is a Gigabyte G-Z170N-Gaming 5. Line out from the PC is a 3.5mm to RCA breakout cable. The RCA ends plug into a Dayton Audio DSP-408. Speaker wires run from DSP-408 to active speakers. (JBL 305P MkII, also tested with a DIY set of active speakers.) With this setup the speakers sound fantastic.

However, if I use my Denon AVR-E300 the active speakers -- both sets -- sound terrible. Attaching passive speakers to the AVR-E300 sounds much better, but not even close to the quality of the PC to active speaker combo.

As an alternative to the Gigabyte motherboard I have also used a Topping E30 to bypass the motherboard DAC through a USB connection. I did not notice a difference between running active speakers on either the PC motherboard or the dedicated DAC. Sounds the same to my ear.

Does anyone know why a PC motherboard would sound so good and an AVR would sound bad with active speakers?

Hello everyone, I’m new to the forum so I really hope I’m posting this in the right place. I am fairly new with car audio but I am familiar with working with electronics/basic multimeter functions as I work with them a bit at work.
So I recently took this amp to a “repair shop” and after I got it back one of the channels is still not working. After speaking with the guy of the repair shop who supposedly didn’t see anything wrong with it after he bench tested it he told me I should sell it and get a new amp. I originally took it to him because it was not powering on which he did fix. I don’t plan on taking it back to him.
Anyways, I tested the amp In my truck myself to find the issue. Power is very good (4g wire) 12.8v at the battery the same voltage on amp. Ground is on bare metal and getting a 0 reading on meter. Remote is coming from radio also working fine.
When I wired up all my speakers 4 + sub the amp was shutting off when I turned up the volume not even too high but I would say a medium volume. Took off all the speakers and tested each speaker terminal one at a time. All work great no issues except for 1. When I turn up the volume or gain on that particular terminal the amp turns off, it will come back on but I need to shut off the remote and turn it back on. I changed rca’s issue still there. Used multiple speakers, issue continued. So I’m pretty sure problem is in the amp. Again this is with only one speaker hooked up to the amp in that one particular terminal. I get sound from it but can’t turn up the volume very loud.
I hooked up my speakers to all other terminals without anything in the “bad” one and amp played fine and loud.
I opened up the amp and very thoroughly looked at it but I don’t see a sign of anything burned or blown. Can someone point me in the right direction to what I should be looking for here? Or what I should do next?

A have one of these critters on the workbench that has let the magic smoke out badly. Unfortunately it is somewhat different to the other 8000 series on Elektrotanya. Can anyone help me out with a schematic please.
Thx, M.

___SOLD___

Hello,
I sell my rack najda system.
It works perfectly, I've been using it for 3 years without problems, I include the remote with it.
It's powered with a SMPS which works great.
On the picture you can see XLR connectors but the outputs are unbalanced. The connector panels can easily be changed for RCA's.

___SOLD___

An estimate is what I am looking for. Housed in a Sonance 1250 power amp a Multizone amplifier 50w into 12 channels or 150w x 6 channels. The rear says 1200w. I guess this might be a 1.2kVA unit? There is no wiring diagram or mfg seal/ logo, just a generic part number with no reference.

Size wise, it sort of checks out... I have 2 other Toroids for comparison.

T1 is Antek 1kva
T2 is Toroid Inc (Now Noratel) 725va unit
T3 is the Toroid under investigation...

.

.

.

Hi,
12DW7/ECC832 contains 1/2 12AXT and 1/2 12AU7.Do you know a dissimilar triode which contains 1/2 12AT7 and 1/2 12AU7 ??
Thanks

Franco.-

Im redesigned (most closer orginal diagram) luxman m02.

Hi All,

Need some help/information on this USA made Transar/atd Current Source Power Amplifier....

Looking for any information and a schematic....

There was a short thread on this started on 2011. My Danish friend Erlend commented on this in 2014, but now the Amplifier has shifted owner to another of my friends, and I promised him to try to gather some info on this.

Ok.

Let me try to express this properly.

It's a bit complicated and multi-faceted.

At this point I'm casting about for a new DAC.

I've been using a PCM63 based dac with a x-coupled Jfet/Mosfet buffer for years - it sounds very good. I listen via a very clean signal path, only a passive discrete"L" attenuator between it and the amp(s). Speakers can be Quad 57, Acoustat III (modified), wide range horns (~250Hz --->~14kHz) with high bass driver + BEAR Labs Quadripole subs (using Crown MacroTech 2400). Amps usually are my Symphony No.1 amp or BEAR Labs SE Mosfet amps (with the Quads mostly). Friends bring tube gear over, so I have that reference point. Easy to hear what "guest" amps, or other gear is doing... very. A rather relaxed and natural sound, not "hot", not "bright".

So, I'm looking at the Soekris 1102 thread, back when it started. Thinking, hmmm, interesting. Forgot about it. Until a few days ago. Then I realized that I had missed everything, and that there were now assembled boards for it. Also had come across the Schiit stuff, and some others that seem innovative.

I also see that Soekris is making a DAC product complete as well, same basic topology, all-in-one with a discrete output buffer (surprising).

I'm wanting to get a handle on both the sound and if it is worth the effort to DIY.

Frankly reading quite a lot of the thread(s) it seems like the Soekris DIY build is not simple and is complicated by things like thumps, outboard uproc controllers, displays, upgraded power supplies, etc, etc. That makes it a BIG project costing maybe 2-3x the board itself. That puts the hardware cost in range of some commercial DACs, before considering the time it might take to build it up.

Then, I'm thinking maybe I can slam the 1201 into a box with bare bones supply run it "naked" and see... but what will that sound like compared to the fully decked out builds?? How much difference? Any?

And sonics, what's the diff between V1,2 and now V4??
Does V4 not need the muting circuit??

But then too, I have no way that I know of to get an audition with the commercial DACs either. 🙁 Or the Soekris for that matter!

The other thing that I think I noticed is that the absolute values of the specs and the look of the FFTs are not utterly spectacular at all?? Seems to me that I recall seeing an order of magnitude lower THD values from previous generation chip DACs?? Am I imagining this?

So, I am hoping for a discussion regarding all of these factors. Especially, IF you're running a Soekris DAC, I'd really appreciate hearing your sonic impressions - hopefully in the context of your system, listening preferences/experiences, and possibly comparisons with other units.

Anyone have a built up unit they might wish to sell or ship for an audition?
(I'm in upstate NY, just in case you are not that far away (NYC <---> Boston)

Looking forward to hearing more...


_-_-

After digesting a long thread about waveguides, some large and going quite low, I was thinking about building something with one. And if big enough, with large woofers, maybe no need for separate subs which are problematic in the space I want to rework next. So typically you end up with a horn in the top part of a tower with some big PA-style woofer below, maybe two. Blah. Or put the woofers on the sides opposed...still not attractive, and not practical for the space.

Then a little thought popped into my head. What if the woofer(s) were on the BACK, facing the wall? Yes, myriad problems come up:
(a) Getting the horn to go low enough...this implies probably a larger horn than there's really space for 🙄
(b) Finding a woofer setup whose radiation would need to be essentially omnidirectional to a pretty high frequency.
(c) The slot between the woofer(s) and the wall could make a resonance. Perhaps some kind of splitter or phase plug could be applied on the back to reduce phase cancellation?
(d) There's a time alignment problem between the horn and the woofers. Maybe with the right AVR* the AVR could power the woofers and in parallel from preouts power external amps with ideally crossover and time delay to power the horns?

What other problems and hopefully solutions can y'all think up?

P.S. If you are objecting that "the speaker isn't backwards, just part"-yeah, you're right 😱

*Yes many amazing solutions are possible with all kinds of multi-box solutions, miniDSP etc, but that's not something this friend would want to get into at all.

For a while now my main stereo loudspeakers have been using a pair of Peerless 830452s in a H baffle. These are very similar to the bass configuration used in the Orion as designed by Linkwitz.

What I have been considering, is doing away with the H baffles entirely and building 4 small infinite baffle cube shaped subs, with 1 XLS per cube. This would allow me to make use of boundary reinforcement and room gain.

The end result would end up giving me greater in room extension whilst requiring less power. Another benefit would be that the main panels would no longer be 'excited' by the vibrations caused by the H baffles that support them.

I know that Earl seems to recommend 3 subs, but this is in conjunction with the main loudspeakers, giving 5 individual sources.

Without the H baffles the main panels extend down to 100hz.

I don't have much, if any, experience at integrating subs into a system and am wondering if there would be any problems in trying this out?

I've wondered for a long time about that old bone of contention "does the speaker load ever appear less than the DC resistance."

IIRC it was Matti Otala who first said an 8 ohm speaker could transiently appear to be 1 ohm
AES Convention Papers Forum >> Peak Current Requirement of Commercial Loudspeaker Systems
which led to Harman-Kardon's "high current" receivers and amplifiers.

But then a later paper-which I very unfortunately do not recall the authors of-said "well, Otala's data was only from simulations, we find no actual evidence of the loudspeakers transient impedance ever being lower than the D.C. resistance"

I'm wondering if anyone has ever tried measuring this* or knows of any other evidence about this?


*I had a scheme where I wanted to rig up a data-output voltmeter across the speaker, another across a 0.1 or so ohm resistor in series to the speaker, then play actual music. Each second or whatever, record both values into a computer, which would then divide the two to find an impedance magnitude. But then I changed jobs and that never happened.

Another approach might be to calibrate a storage oscilloscope running an X-Y I-V plot-the slope of the line for a sine wave would be the impedance, so presumably you could look at that and see if the slope ever goes past the DCR value (which you could calibrate with an actual resistor).

Both of these idea may not be quite right-I haven't thought about this for a long time.

Hello
I have a question and maybe a favor to ask
Who here uses or had any tv tubes ?
Don’t some tube amps use tv tubes ?
Reason why am asking for some free ( donated ) TV tubes, is I acquired a mint ,technicians vacuum tube rejuvenator , for TV tubes. And is like to give it a try to see how it works.
It’s made by B&K , model 465 CRT tester
So if anyone can help, I would really appreciate it. Please send me a message or post openly about your knowledge involving TV vacuum tubes in an audio circuit of amplifiers

So this is a flat indoor antenna. It is very good. Brings in stations very clearly on my Dynatuner FM3 which is not known for exceptional sensitivity, as good as a dipole on my Tandberg 3001A. The FM3 does not do well with the dipole. I'm just curious if piggy backing two of these would be even more powerful?

Good morning,
I found 2 audiobahn aw1206t subwoofers in my garage. I have never rebuilt a subwoofer, but would like to try. I was going to use the baskets but need help to find replacement parts. I already know I'm going to get **** cause they are audiobahn, but instead of throwing them away, I want to.use them to build and learn.

Guys

I'm building an S/PDIF switcher with Twisted Pair's 4:1 Mux/Demux board and I'm wondering what wire to use for internal wiring between the board and the RCA connectors (±10cm each). Do I realy need coax for this or can I get away with something else?

Regards

Im looking for speaker /maybe full range/ for RCA Victor SA-20, 8 inch.

For sale a pair of NIB Ciare NDH 15-4S 8 Ohm loudspeakers.
New, never used or connected, in original boxes.

Price: 450 EUR

Shipping from Kazakhstan, 60 EUR to Europe, 70 to Americas, registered airmail with tracking.

Buyer pays paypal fees, offers are welcome.

I don't think bringing the name BOSE might go well with people!

But, there are some decisions which makes me wonder why they are taken and the benefits which it might bring!

As title suggests, I'm still wondering the decisions that went through when these speakers were finalized.

Why use a dual opposed driver for full range?
What advantages and disadvantages does this setup bring?
Can this work on any other driver?

Your thoughts please?

(Attached the image just for information! Credits:BOSE)

Hello, Everybody.
How are you doing?


I'm designing an STK4231II amplifier, with an original part that I have for more than 20 years and never used (precious! 🙂. Just to relax, rsrs.
I started with the Sanyo's reference design, to calculate gain, poles, bandwidth, protection, etc, with further reading of some services manuals, just to see what there is out there, and I found something curious that I can't explain well. On the services manuals (more than one), the designers have placed a small capacitor across STK's inverting and non inverting inputs. After some matlab and LTSpice, this capacitor creates an additional pole at around 40MHz, using an ideal model of an operatinal amplifier.
Does anybody know the reason for this spending? Maybe for susceptibility compatibility? The designer has placed this small capacitor across all the operational amplifiers he/she used in the equipment

Hi i need help with this amp everything is working but no switching on the output section

Boy, who knew 'cosplay' was such a large business (search for 'EVA foam')!

I have several cabinets to make with 12" speakers (12.2" outer diameter).
These are FRFR cabinets, speakers are front loaded and I need material to make gaskets out of.

From reading other posts EVA foam seems to be the way to go. I am looking for EVA foam that is soft enough / suitable for gasket material ('cosplay' EVA foam seems to be to 'hard' for this purpose). 'Craft' type sheets seem to only come in 12" x 9" sheets with unspecified hardness.

Anyone know where I can get EVA foam wide / tall enough to cut gaskets from?
My preference:
-- 1/8" thick maximum.
-- 'Rubber Band' softness (Shore A: 20, Shore 00: 20).

Or anyone with other ideas for gasket material (No tape, whether striping, or 'goo' type material. I want to cut the gaskets from sheets) and possible suppliers would also be appreciated.

I am in the U.S.

Thanks.

I have a very nice Heathkit IG - 37 for sale. This unit works fine and comes with a very nice factory manual, plus both factory cables. The very hard to find 300 Ohm twin lead connector that plugs into the front of the unit is included. The 300 Ohm twin lead still has the factory alligator test clip setup, that connects to the tuner's external antenna posts also. Price is 125.00 US dollars, plus all shipping/tax costs to your doorstep. No Paypal. TIA

Hey everyone!

Disclaimer: I'm fairly new to diyaudio, amplifiers, power supplies, schematics, PCB design and everything that this forum touches on (read: noob), so I urge you to be patient with me - I am eager to learn though.

That being said - Hi! My name is Mladen 🙂

Anyway, on to the point: Recently I came across @xrk971 thread Hakuin SE Class A HP Amp which got me interested into building my own amp (PCB design and everything).
But, since X hasn't opened source his power supply schematic I decided to tackle that on my own (without some extras he implemented). Basically what I tried to do is: Battery Charger --> Boost Converter --> LDO.

Spent last few days reading through data sheets and reference designs and this is what I came up with. I would greatly appreciate if you could fact check the schematic and suggest things I should do (things that I've probably missed).

I plan to use Samsung's EB-BJ710CBE battery (if possible).

Data Sheets:

MCP73871, TPS61178, TPS7A470

I have to sell Brand new dayton Spa 250 dsp plate amplifiter
price $100 plus shipping

best regards
myintv

I have one of these in for repair that has been modified......anybody have a schematic please ?.

Eric.

Empty Munro Egg 100 enclosures going cheep on Ebay UK!

From what I can find out, they are normally populated with Peerless by Tymphany BC25SC06-04 tweeter and possibly the SDS-P830855 4".

I've bought a pair, I think I'll put Monacor MSH-115 and a cone tweeter in using a shaped MDF baffle or two.

Pair of Egg Shaped Speaker Housings - Colour Red - (24) | eBay

I have the Sherbourn PA 7-350 power amp that I bought from Emotiva when they had the clearance sale. This is a really solid and well built amp but it randomly shuts down due to its protection circuit kicking in. Sometimes I can watch a whole movie without a problem and sometimes it shuts down in about an hour. Here are things to note:-

1. The shutting down is not related to volume, it can shut down even when nothing is playing.
2. The shutdown is not due to overheating problems as the amp is in a well ventilated place.
3. Shutdown is accompanied by mainly the channel 7 lights blinking which id the front right speaker with occasional channel 6 light blinking which is the side right speaker.

Remedies that I have tried:-

1. replaced my XLR cables between pre/pro and amp but it made no difference.
2. Replaced the speaker cable for both those channels but no difference.
3. Swapped speakers to rule out any speaker problems but nothing changed.
4. Swapped the XLR cables to ascertain if it's my pre/pro but no change which means my pre/pro is intact.

Things that I will be trying:-

1. To disconnect all speakers and check wiring to rule out lose connections on all channels.
2. Bypass the 20Amp mains power stabiliser/conditioner that feeds the amp.

If anyone has any experience with such matters then help will be appreciated as I'm still in the process of trouble-shooting.

I'm wondering if there are other members of this forum who are using the same power-amp.

I'm hoping that it is not an over-sensitive protection circuit - any electronic enthusiasts or engineers here that would know how to resolve this?

Wood chips/shavings from woodworking machines is easily available in my locality. I would like to ask whether packed woodchips/shavings can serve as echo mufflers like fibre glass slabs? The reason for asking is ease of purchase and price. Please, be aware I am not after making studio for professional use but only a room for music play back without dominant room modes.

My idea is to use carton boxes of medium rigidity, cut them in the shape of prisms, and fill them with woodworking chips compressing the latter with my hands. That way, I should reach a certain density.

What do you think? Room modes are still ruining some music tracks and these tiresome modes seem to be sensitive to air humidity and temperature.

Hi everyone,
I've just posted my introduction and here's my first thread on this great forum.

A few days ago I aquired an Audio research D90 (not a D90B) which is populated with Electro Harmonix KT90 power tubes and an EH 6550 regulator tube.
The amp was in a doubtful condition:
-aged soldering connections (already solved since yesterday)
-Lousy aftermarket loudspeaker sockets (I fixed it up to the point where at least it's safe to operate; should do more later)
-It was badly mis-adjusted. (especially the DC balance was farrrrr off...

I did a full adjustment as per the guidelines of ARC and found the amp to be working well, with a few things I like to ask advice on from more experienced users:

-Heat: Even without the top cover, the power tubes get blazing hot. And not only them, the power transformer gets very hot as well. (too hot to touch after a few hours of playing.) Is this normal?

-With the above, please note that I biassed the KT90's on 65mA (ARC suggestes an even higher bias of 75mA. Would this make a big difference on the sound?

-The power transformer is buzzing / rattling loudly. I can hear it through soft passages in the music. I'd like to make it more quiet. Plastic spray came to my mind, but I think that given the temperature of the transformer, this isn't wise. Any suggestions?

Thanks for reading this 🙂 I'm looking forward to know ya all a bit better and to get my D90 in perfect shape as well.

hello,

what do you think of this design for a vented concrete box?

the driver is Tang Band W8-2145 8"
spec-sheet
the box volume is ~ 5550CM3

can you help me figure out if the box volume is big enough and what are the port measurements?
and one more question, would you use a close or ported design for this driver?

I'm building a pair of subs each with 2x Dayton Audio SD215A-88 8" drivers and a single 4" flared port.

With a target volume of 3ft^3; I'm wanting to make it roughly the same footprint as my Infinity Towers, which is 12" deep (outside). If I assume 1/2" MDF/plywood and a double baffle, that gives me 10.5" deep (inside), but with my port flush mounted, that gives me 11.5" from the front baffle to the inside of the rear wall. My 4" port (actually measured 3 15/16") needs to be 8.5" long to produce the tuning I want (31Hz) plus the flairs. The flairs are 1.25" each end or 2.5" total, so my total port length, including flanges, is 11". That only leaves me 1/2" of space between my rear flange and the rear wall, which is obviously not enough space. If I bump my depth to 14", I have 2.5" of space to work with, which still seems a bit tight to me, but I'm not really sure why.

My question is, how much space do I need to leave between the rear of my flange and the back of my speaker box to avoid unwanted effects? Is there a general rule of thumb with or without flairs? Is it based more on air speed than anything? If it matters, I'll only be pushing 100w total through both towers (50w per tower), so at 50w each, that a port velocity of 16.5m/s. If I were to hook it up to a bigger amp and run a full 160w through each tower, that would be 30m/s.

I built the temperature compensated LM334 current source (Figure 1 below), configured for 5.5 milliamps: R1 = 27R and R2 = 270R and D1 = 1N457A. When I put it on the curve tracer to sweep out its I-vs-V curve, I got quite a pleasant surprise: the LM334's "knee", where it ceases acting at a current source, is at a relatively low voltage: 2 volts. See Figure 2.

Linear Technology's datasheet suggests adding a JFET with large |Vpinchoff| as a cascode (Figure 3). I tried this, using the J105 device (Figure 4). It only moved the "knee" upwards about 200 millivolts or so, maybe to 2.2 volts: Figure 5.

I was pleased.

diyAudio members who have created an LTSPICE model of the LM334 and the J105 and the 1N457A, may wish to simulate these two I-vs-V curves and see whether measured data matches simulation results.

_

Hi guys,

What's the difference between a Threshold SA/30s and a SA/3.9e apart from the typenumber?

Thanks in advance

Does anybody know the loudness specification of NAD 3020? I couldn't info about it although found many schematics or service manuals on the internet. I'd like know what frequencies does its loudness boost and how much dB of boost? Thanks in advance

closed

Bought a pair on parts express deal of the day. Wanted to put them in sons truck. Decided to play around with them first. So used them to put some time in on my new printer. I am very impressed. Sound great
Especially vocals for such a small setup. I find they breakup a little up high if anything. Thinking about printing a single box for 2 when I reprint these. Make it a portable speaker.
If only I can figure out a micro sub to go with them fir just a little extra.

When driving a speaker on a long cable, what is a safe capacitance to design an amplifier to be stable driving? Would 10 nF be a sufficient maximum capacitance or 100 nF? I measured some audio cable at about 400 pF/m, but I would guess that the variations in setups might produce higher capacitance loads. Are audio amps ever designed to be unconditionally stable with respect to capacitive loading, and if so, how? Given that oscillation of an amplifier could produce a catastrophic effect on a speaker if the amplitude was high enough, I would think this might be a consideration to maintain SOA.

Hi All,

Fairly new here 😁 thought I'd share here some of my story repairing and restoring a "parts" HA-4700 from TradeMe. If anyone's interested.

When I got it, the lights were on but there was no output at all.

What I found was one channel with the output emitters sitting around 8v, the other at the + rail more or less. Dead output on that one I thought. But it turned out that every single 1/4w "fusible" resistor in the thing was either high Z or open. This was the same problem as was found in the excellent YouTube video by JoulesperCoulomb which was what prompted me to start checking them.

Replacing them all with standard metal film resistors ("fusible" resistors in those values proved hard to come by and normal metal film resistors should work well enough at failing open if need be) brought it to life except for a several megahertz oscillation (another problem also found in the video! These must be reasonably common issues) which was due to some of the (weird) axial caps gone bad. Replaced those with mlcc type and that sorted it! Adjusted the bias and DC offset and was away. A few dry joints fixed along the way and of course new thermal paste for the power trannies.

Knowing it was serviceable, I moved onto cosmetics, restoration and tidy up. So far
* Replaced 8200uF bulk caps with 10000uF CDE caps. They actually tested fine at over 7000uF apiece but 8200 seemed kind of small for a 50W amp anyway.
* Replaced dead "TAPE" bulb with yellow LED
* Replaced incorrect 1N4004 diodes on indicator/selector board with the correct 10v zener
* Removed case bottom for corrosion and paint repair

Still to do:

* Replace other indicators with LED
* replace a switch I broke 😭 which is going to be tricky
* polish up the chromed buttons and knobs best I can, they're a bit corroded (green spots)
* Clean up rust on case and repaint
* Clean up rust on transformers and paint
* Receive new volume knob (was missing)
* Reassemble!

If people are interested I have loads of photos so... Let me know if you wanna see them.

Here's some pics of the state I got it in... Fairly rough:

"Parts" Hitachi HA-4700 Original State - Google Photos

Good Day to all. I am about to repair my personal JL Audio 1000/1 again, that I had repaired twice before over the 5 years I have had it. The first time it went out when I mistakenly wired it to 1 ohm combined with low voltage, and the second time I believe it was low voltage alone. I will start the repair thread by first asking for help to select the PS FETs and outputs.

PS FETS: The amp originally had IRF3707 in the power supply, and I used IRF3709Z both times previously. I am unable to find IRF3709Z available at this time so I am looking for advice regarding what I should use. Using alltransistor.com equivalent chart I personally think IRL3103 would be a good substitute as the specs are very close to the IRF3707 according to the attached chart. Digikey suggested the IRLB8721PBF as a substitute. The gate resistors were changed to 22ohm to work with the IRF3709Z.

OUTPUTS:. Don't know what was originally in this amp as the previous owner had tried to repair it with IRF540. I had used IRFB31N20D both previous repairs. What would be the best choice for outputs this repair?

Hello all,

I am starting to dabble in a active speaker setup, using a Xonar U7 MKII for a simple active 3 way mains, 2.1 setup at my desk. I am wondering, how someone would setup a 5.2.4 setup for an active home theater?

Are there any 15, or 23 channel devices that cost less than my house? Is that what would be required?

Is there a way to use multiple Xonar U7 MKIIs without having huge timing issues?

A more realistic idea, how would someone "actively" control just a center speaker in a basic AVR setup? Or just the left, center and right?

Sorry if I am using the incorrect terms. Pretty fresh on my DIY audio adventure.

Thank you.

Ive been wondering, for a while, why so many people believe the audio myths and why theres so many. Always had the feeling the internet was at its root. Now I have some evidence.

The Social Dilemma | Official Trailer | Netflix - YouTube

Fake news spreads 7 times faster than the truth. Everyone has there own truth, and since it makes money for the rich this will continue and get worse. When people get there "facts", that are customized per individual, from social media what do we expect. How have we become such sheep?

I hope Ive enticed a few to watch, as they say the cure is knowledge.

Hey everyone.

I am in the process of designing my first tube/SS hybrid.

The original idea was a single ended design, but for the price of another tube and a couple of resistors and caps, push pull becomes an option, no?

This is the preliminary design.

If I understand it right, this should work as a class A push pull amp putting out about 20W? I could also change the top 6N3P for a 18k resistor to save a tube I think...

Koda

I have a 1971 Fisher S-695-IP console, with the following speaker compliment per side:

Qty 1 - 12” Rola woofer, 8 Ohm
Qty 2 – 5” Rola mid-range speakers, 8 Ohm each, wired in parallel (effective 4 Ohm)
Qty 1 – 3” CTS tweeter, 16 Ohm

The crossover is comprised of the following:

Woofer: 2.6 mH air coil/inductor
Mid-range: 5.6 Ohm resistor, 25 uF capacitor, .5 mH air coil/inductor
Tweeter: 4.7 Ohm resistor, 4 uF capacitor


Since the console is now 50 years old (wow how time flies! ) the old capacitors in the crossover are due to be replaced. And of course normally that would be all that is required, especially if no changes in crossover design or driver are to occur.

And normally I would approach this simple rehabilitation with the intent to make no changes and keep the design and drivers as manufactured by Fisher in 1971... effectively just replacing the capacitors with the same values and move on.

However, I have a few observations that lead me to consider modifying the crossover and replacing the tweeter with something more modern.

Fisher speakers are known to be voiced, as many manufacturers do, for a specific style and taste. Fisher was known to voice their speakers more toward vocal, classical, and jazz versus many of the styles that are popular today. With that in mind it seems from my listening and other subjective reviews that Fisher speakers seem to slightly mute or roll off the upper mids and highs a bit to perhaps “soften” the sound. And this does seem to be the case subjectively when listening to this 1971 Statesman console.

In addition, the use of 3” paper cone tweeter likely plays a part, even after replacing the capacitor, and noting that prototyping its replacement with a small soft dome really pleasantly brightens up the sound.

So, my first thought was to replace the OEM CTS 16 Ohm paper cone tweeter with a soft dome. But finding an appropriate new 16 ohm tweeter is challenging, and I found none except for a very expensive horn that isn’t a good fit in several ways.

But that’s not a big deal theoretically of course, as I simply need to modify the capacitor for the tweeter to accommodate an 8 Ohm modern tweeter, and leave the rest of the crossover alone.

However, this is where I am asking for some expert analysis of the OEM crossover before I change anything.

If I run the OEM crossover points through some online crossover calculators, it seems that the factory advertised crossover points of 2500 & 400 Hz may not align with the capacitor and coil/inductor values that are actually installed. There seems to be a big frequency gap between the mid-ranges and tweeter, and it takes choosing some wildly different crossover values to make the OEM capacitor & coil/inductor values to get even close... but not at the same time.

But I’m admittedly not an expert crossover designer, and along with the capacitors & coils involved, there are also a couple resistors in play.

I know that typically a resistor in a crossover may be used to attenuate a driver, and normally isn’t used to change the impedance of a driver, but I do wonder if perhaps it has a slight effect on impedance and thus influenced these crossover capacitor & coil/inductor values in a way I don’t understand and the online calculators can’t take into account.

Also, I realize that we don’t know a lot about the drivers themselves other than the impedance, and obviously the manufacturer did have that data. So that leaves us at something of a disadvantage, but really in this case I’m only concerned about the mid-range and tweeter portions so the bulk of the T/S parameters probably aren’t that relevant.

But sensitivity is relevant, however without objectively testing the drivers or having their specifications we’ll likely never know, but I can say it is likely that they all are high sensitivity given their vintage and the relatively low power (30ish wpc) of the receiver.

Whew… OK 🙄


So can someone with some crossover expertise look at the OEM design and try to explain how it is working to deliver the specified 2500/400 crossover points, or discern if there are any issues with that design such that is is not delivering the specified (or more ideal) crossover points and if so what component values should be modified?

And with that in mind, and my plan to replace the 16 Ohm tweeter with an 8 Ohm tweeter, what component values would be appropriate to change in the crossover?

Thanks in advance!

First of all hi, pretty much an absolute beginner here.

I'm just starting to get into amplifier design, and the variety of parts is somewhat... overwhelming. I guess I could semi-blindly pick, but I thought I'd use the wealth of information on this forum to ask:

What're some decent, generic parts that you'd recommend keeping in stock and using for designs? Nothing hugely special, expensive or obsolete. Stuff like small signal transistors, some complimentary models, some output mosfets. Capacitor brands you trust or have had good results with, or other devices like voltage regulators if they're not too specific to the application.

I'm sorry for the hugely vague question, and thanks in advance!