Ohoj!

Saw this test:

PureLow LO Subwoofer | Hi-Fi+

they seem impressed but price is *steep* to say the least... Maybe some here has a cheaper recipe and even tasted the dish?

Care to share?

//

Why does this parallel quarter wave alignment cancel out every frequency after 860,(1720,2580,3440,4300…14620,…19780….end of horn resp…(-990dB)? Those are sone really unique numbers… diameter of the sun, minutes/seconds in a day…or 48,96,192 hrs… procession of the equinox, (2580) Number of days in Leap yearsidereal(14620))

location if planets, etc… This things got it all…?

if it starts canceling at 860 which is 10 cm.

that’s the basis for the speed of light previously? Per Wikipediaz . And the 8/254 version of ‘pi’’ is 3.1496. This last spike in the response is exactly 149.6hz? Following one is at Mars to 236milion km/hz /uranium before fission? And filling in the three(1/4) harmonic but not at the 5(1/4 at that same location, And then the meteor bekt in all of that? Prior to the dip right where Jupiter is 475hz…


weird stuff that goes all the way back to offset driver to El Azteca driver position found in those. Which is essentially what’s being done on both sides of this in the first segment of each.

Hi,

I have a pair of bifilar 1:1 transformers from intact audio that I used at the output of a 71a preamp.

Looks like Dave doesn’t make these anymore based on his current site.

70H 20mA.

$400pr OBO

Hi all,

After along search I have finally found something of an audio holy grail, for me at least. A Cambridge Audio CD1. As all CD afficiendos will attest this is something of a notable rarity. Being apparently the first 2 (or 3) box CD player ever made, and the only one ever to use 3 TDA1540's per channel. The sound it produces is dynamic, liquid smooth, analog in nature, with the widest sound-stage I have ever heard from a CD.

My particular example had been packaged carefully and slumbering in a box, in an attic for many years. As a result I have to say it is in almost new condition. I had been using it for a week or two without fault, but have now noticed a grumbling gear noise when the CD drawer is opened and shut (occasionally needing a helping finger to finally close).

Not wanting to cause any damage I have decided to stop using it while I sort out the problem. The drive is a straight lift from the early Phillps players, that is the CDM1. As most will know this is a long lasting unit and mine shows no problems tracking and reading disks.

I have replaced CDM1 mk2's, CDM2 mk10's and other drives in older machines with direct replacements, so I'm not a complete noob in this. As many know though the drawer mechanism on the CDM1 machines are quite complex and before I strip it down, I would welcome some or any advice on what the gear noise issue may be, so that I can be forewarned.

I have attached a short video which hopefully shows the problem.

Thanks and best wishes to all.

Found a couple of PCB's for an AlephJ. Asking 10 euro each.

Also would have parts for them as well like 2SJ109 and selected IRFP240's

new in box, $125 each plus shipping. Also have 3 nc400 amp modules, new in box, for $300 each. Will discount if all items are purchased.

$1000 for everything. Buyer pays shipping. Thanks.

Well, I've wasted hundreds of £££ paying for 'protection' on parcels over the last years with parcel2go.com

Their cover does not include speakers or amplifiers.

I'm not saying don't use them. ALL couriers and agents try to get out of paying for damage. Just don't waste your money on protection.

I'm glad they highlighted this when I entered the item description as 'loudspeaker' or 'amplifier'. NOT!

Hi All,

I posted earlier that I have readable schematic for this NAD 3240PE. I am happy to share that, if anyone want a copy.

Now I have to try to solve the problem - the right channel doesn't respond to the balance adjustment as it should.

The amp sounds very nice, completely noise free when nothing is playing. IF I turn the balance knob all the way to the right and then just a little left to get some left channel going I can turn it up and get very pretty sound, but the right channel has only a tiny fraction of the left channel power.

If I take the Pre Out to another amp it sounds just fine, but when I use the integrated amp not much right channel.

I am surprised by this, I would have expected the balance pot to be a preamp failure, not manifested by the power amp alone.

I tried the usual contact cleaner hose out and rotate business. No difference.

I am attaching images of the schematic (the rest of the service manual has component lists, wiring diagrams, etc.) that can be placed side by side.

I probably just don't understand how the switches and pots work together and all I need is a new balance pot, but I could use any trouble shooting advice you all are willing to share. Should I go for a volume pot, too - while I am in it?

Thanks! BentMike

Hi all,

I recently bought a 300w sub with a broken power board for 15 quid.

I stripped out the power board and the fancy low pass filter, frequency modulator, and volume control board out. Then bought an L7 MOSFET mono power board that supports 300-350 W at 8 ohms as well as requiring 2x 50 V in, this is exactly what the transformer outputs and what the driver requires.

I also picked up a 2M ohm potentiometer for volume control and a 100Hz or so highpass/lowpass filter (i always get it the wrong way round)

because it's a mono out board I'm having a lot of trouble trying to work out how to correctly wire it all?

Any help?

Finlay.




(https://www.ebay.co.uk/itm/221254643945?_trkparms=amclksrc=ITM&aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=20200818143230&meid=f1091f7470794e6eb76178fa92c156f5&pid=101224&rk=2&rkt=5&sd=224405663394&itm=221254643945&pmt=1&noa=1&pg=2047675&algv=DefaultOrganicWeb&_trksid=p2047675.c101224.m-1 link for power board)
(https://www.hifigear.co.uk/epos-els-subwoofer.html link to sub)

I've read a bit about capacitor microphonics being a problem and have read that some have zip tied caps to the board or used hot glue. About ten years ago, when I built my first outboard, I put the caps on thin sheet rubber and secured them tightly to the board with zip ties. But now I wonder if the vibrations causing microphonics are within the capacitor and securing them to the board doesn't eliminate the problem. Is that the real problem or are zip ties/hot glue the cure?

Credit to Mark Johnson's design

4 used stuffed boards in great working condition @ $9 per board + shipping & paypal fee in continental US. They're stuffed with 50v caps.
10 bare boards @ $2 per board + shipping & paypal fee in continental US.

EDIT - ALL ARE SOLD. THANK YOU!

Note that the bare boards have mounting hole and are thicker ones. If you decide to pay like gifts then there is no fee. They're small and I'll use first class mail. Don't know how much it costs to ship, figure 4 - 5? If it costs less to ship I'll refund the difference.

Thanks for looking.

Duc

Greetings to everyone!
Own this C.E.C. TL51XR cd player is about 2 years and now I decided to make major changes! I was inspired by this for upgrade digital modules: cectl51x

I started with the power module. Here I replaced all regulators with Newclassd UWB DX78XX/79XX regulators.
Photos before changes.

Hello, wondering if anybody knows where I can purchase an amplifier that has the same sound signature as my pm860

I have owned and repaired quite a few of the little Soundcraftsmen PCR-800 & PM 860, pro power series etc amps and found them to be excellent performers.
Even Audio mag reviewed them highley, slightly better then the Adcom 555 amps.

Has anyone else played with these and done any mods?

How about the PCR, Phase Controlled Regulation power supplies? i have never seen another company use such a design? (maybe for a reason?) any thoughts on the PCR design??

I have done some simple mods like upgraded the PSU caps and added bypass caps, cleaned up the internal wiring and upgraded jacks etc.

These ******s can be had really cheap and they sound pretty good. My Bryston 4B had better bottom end, but these seem a but less harsh on the top end.


Zero 😎

Hello,

building two pre-amps using this http://www.tentlabs.com/Products/page31/page31.html

As far as I understand it, it does have a self-power off function )perhaps if no signal detected for some time? Can anyone confirm as Guido`s not answering my emails (hope everything is allright with him)?

hi all im starting this thread in the hope its as popular as the beringer thread and to give everyone who has any of the dbx driverack units a place t5o discuss everything about them including setup,modifications and others .ive personaly got a new driverack 260 that is going to biamp my new speakers which are 2way with eaton 12" hexacones for bass and manger transducers for the mid and highs .im using 2x goldpoint attentuaters for volume control in between the dbx and the hypex ucd400 hg modules which have the superregs fitted .once setup id like to do some mods on the dbx to see how good it can sound .ive got some ideas which are to add an outboard powersupply ,some cap upgrades and maybe play around with the opamps and clock .im hoping all the other dbx users will chime in with their thoughts and suggestions

I just picked up four of the russian 6N7S tubes with the aspiration of puttng together some type of class A (AB-leaning-heavily-A at least) push-pull amp. I chose 6N7S's because they are readily available and they put out a decent amount of power. I was a bit surprised to see that they've been traditionally used for pure class B, but I hope they have some real hi-fi potential.

If each bottle has a 12W max dissipation, I'd dissipate around 20W per pair, hoping for around 10W of nice audio. Is this feasible? I don't have a printer so I haven't done any load line drawing, but let me make sure: with the PPP setup, the load impedance that EACH triode sees is the same as the anode to anode impedance of the OPT right? Any ideas about what OPT primary impedances might be best for such a project?

I'd have to look at some load-lines to see how much swing is needed to drive the tubes but I have a few 5687's kicking around that hopefully could be up to the task. Maybe an LTP feeding a regular grounded-cathode stage? a LTP'ed SRPP?

If such an amp isn't practical I'll just save these to use as somewhat beefy drivers for another future amp. Planning ahead, I am 🙂

Does anyone have any Avid Turntable repair info??? I just repaired a Volvere and I need to know the value and speed rating (fast or slo blow) for the 2 fuses inside the power supply/speed controller unit. I have reached out to avid several times with no response so far.

Hi, looking for a valve amp, can be as low as 4watts for my kirishima speakers, more than 95db
Up to £2k
Ideally single ended.
Thanks.
Graham.

Recently i made a gainclone based amplifier & faced a weird phenomena. For test purpose i was using a simple opamp gain stage(6dB) to boost the output signal of a Bluetooth mp3 player. For preamp & mp3 player i used 7xxx based regulated power supply. Anyway when i was turning off the whole thing there was a terrible loud thump /squealing after 1-2 second. I tried different opamps (5532/072/353) but result was the same. I checked almost everything but i failed to get any clue. The mp3 player was connected to the positive rail of the preamp, to find the problem when i disconnect its supply(5v) everything becomes normal, no turn off squealing. Then i realised it was happening because positive rail collapsing faster then the negative rail & it turned out to be true! I added a LED load to the negative supply rail & voila! No turn off squealing now 🙂

I thought i should share this with everyone. Anyway have a nice day folks!

Hi, everybody...

I'm somewhat surprised that I haven't found any good information on this, so I thought I would pose it to you smart folks!

Before posing the question... a quick preface: I'm not a total noob (maybe noob-adjacent), and although I'm not a physicist who can tell you about the more technical aspects of port dynamics (e.g., laminar flow, etc.), I am familiar with their general forms and functions and all that goes into their calculations (trying to stave off questions about why this or that port is better, how to convert one port shape to another, how to calculate port length, etc.).

That said, here's the question (maybe with a few parts, if you'll indulge me):

Let's say you have a 40" port like the one outlined in black below (and the port SHOULD be 40" long)...

(a) When you add 45-degree corners to facilitate air flow (in red on diagram), how do they affect the length of the port? Or do they? Some have suggested that they don't (and that might be true!), but to my pea-brain, if the air volume in that port affects the compliance of the driver, wouldn't changing that volume (even a little bit) have SOME effect on the overall system? I imagine that you would add a wee-bit of length to the port to account for this, but I'm not at all comfortable with that 'conclusion.'

For extra credit...

(b) When you add those 45-degree pieces to the port, how far should they 'intrude' into the port (see blue and '?' on diagram)? All the way to the mid-line (noted in gray)? Somewhere in between? Is there a rationale or calculational justification for one way or another?

And if you really want to make my day...

(c) Is there any value in 'rounding' the corners in the enclosure itself with 45-degree angles like the ones in the port? Sometimes I see it... sometimes I don't. That just something I've always wondered about!

And if you're in a "Holy cow, I'm feeling generous today!" kind of mood...

(d) Looking at this box design, do you see any 'red flags' (not aesthetically, bracing, or how it might be done otherwise)--just any "Dude, you can't do that!" reactions to the overall layout?


So, if you'd like to take a crack at (a), (b), (c) and/or (d), I would greatly appreciate it. Thanks, forum! 🙂

I started building a JLH '69 several years ago including some nice home made pcb's. However, it hit some snags along the way and never got finished. Recently I tested the power supply and found excessive voltage sag under load which leads me to doubt that the transformer is up to the task of a stereo unit so this is going to be a mono block.

The details got spread around in the extensive thread on this topic, starting back in April 2011 [http://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-48.html#post2545677] ] and it's hard to keep track of what I was doing so I've opened this thread to capture it and hopefully get the thing finished. Maybe when it's all done the Mods can append this thread to the original monster.

Contraints: I want to use up the bits I have in my junk box and use the half built chasis that I have. This includes all the old RCA 2N3055H's that are rivetted onto the heatsinks. They have date codes spanning 1981 - 1982 (recovered from an e-waste power supply) and I understand they have ft of 2.5MHz. I consider this project a kind of 'industrial archeology', so I won't entertain any notion that these output devices are unsuited. The challenge with older devices is 'beta droop', in other words a significant decrease in input impedance at high current.

Hiraga's advice was to select devices and operating points so that the dc operating current occurred at the peak of the current gain so that the drop in Hfe with the signal swing would be symmetrical. In any event, it's good advice to avoid operating the devices in a region where beta starts dropping off quickly. The datasheet for 2N3055's puts the peak Hfe at around 200mA at most, especially when hot. With a target idle current of 1.6A we'll need 8 parallel output devices. I just happen to have that number on the heatsinks.

The phase splitter / VAS is TR3 and it's performance has a big impact on the distortion profile and total THD of the amplifier. I will use a better device than JLH had available. I will also consider using a Sziklai (or CFP) compound device for TR3; this suggestion was made by Homemodder in the main thread sometime ago (Feb 2012) and also by Hugh Dean (in private correspondence).

The attached sketch shows the new direction I'm now considering. Whilst it has only a single rail supply, I've 'moved the signal ground' in order to move the output capacitor to a less harmful position - making it resemble a dual rail topology. I think this approach has been tried by others and works well.

I received a LTB notice on the Fairchild/OnSemi MOSFET FQP3N30 today from DigiKey.
This is a N-CH 300V 3.2A TO220-3 part.
Here's one link to a datasheet
LTB date is 6/23/2022.
Just a heads-up in case anybody thinks they want some in the future....

Bang & Olufsen Beovox 5700, classic vintage loudspeakers restoration, renewal, repair

I acquired these speakers a while back.



The speakers looked terrible, they were scratched and smeared with white muck / paint, dusty and very dirty and sticky. At the top were circles in the wood of lime/water that had leaked from flower pots or something. The foam dust caps in the woofers were completely perished. The pieces of foam fell out when I removed the front.
One of the resistors in the filter of a loudspeaker was completely burned out. Most electrolytic capacitors had wrong values and / or had an ESR of 1 to about 2 Ohm.

What have I done?

• Crossover filters largely renewed / upgraded, all wrong value electrolytics capacitators of 44 years old off and replaced by Jantzen audio MKP capacitors that virtually do not age, and have much better specs (especially much lower ESR).
• The orientation of the coils adjusted to reduce crosstalk. To my surprise, Bang en Olufsen had not paid attention to this at the time of manufacturing.
• The Rosewood veneer completely refurbished, all stains and the scratches and dirt removed, sanded and then oiled again. Sanded with grit 180 and grit 240, sanding only in the longitudinal direction of the wood grain! Treated the surface with hard wax oil from Rubio Monocoat.
• All units airtight fitted with new sealing tape.
• Mounted decent speaker terminals at the back, instead of the loose wires through a hole from the speaker.

They play excellent again, these are really fine speakers!

Any opinions or remarks?

These were the most expensive speakers of Bang & Olufsen at the time.

The specifications:
B & O, Bang and Olufsen, Beovox 5700, HT 5700, type 6253
100 Watt max. Power
impedance: 4 ohms
Frequency range: 35 - 20,000 Hz
max. harmonic distortion: <1%
woofer: 22.5cm Philips AD 1056 / W8
mid tone: Celestion MF 500
tweeter: Celestion HF 2000
passive radiator 25cm
crossover frequencies 600 - 6000 Hz
dimensions: 36 x 66 x 30 cm
weight: 22.5 kg
version in rosewood / rosewood veneer








Philips alnico woofer AD 1056 / W8




The philips AD 1056 / W8 woofer, the foam dust cover remnants for removal


New linen dust cover glued in, temporarily fixed and weighted with a glass










The crossover filter after upgrading with Jantzen Audio cross-cap MKP capacitors. The coils are rotated to minimize mutual crosstalk through the generated electromagnetic fields.




The old components, with the burnt-out / broken resistor of 22 ohms



Above review of the speakers from the American magazine: stereo review, number 3 from 1972

So I just got this Kicker 06 ZX1000.1 in as part of a partial trade towards other equipment. It’s “blown” is all I got, but power supply tested “good” via DMM on main terminals, charging caps, so I opened it up, safe to say I am the only one who’s ever opened this amp up in 16 years, all factory glue still intact.

I found the problem right away, you can see near recitifiers what looks to be “rods” near a hold down screw, found some stray wires near it and (yet again) looks to be the reason why this amp blew, making contact between those rods and the screw/heatsink. So far everything else tests good, removed all FETs and they all seem to be within spec. Inductor was bouncing around as well but still tests good at 200mH.

But I saw something I haven’t come across yet, so I asked other techs and was told it was prolly an engineer who did it, a “decoupler to reduce noise”? Per later board revision, components being unpopulated, and the fact all factory adhesives still instant, etc also pointing to a kicker engineer doing this.

My question is, is that little inductor marked 103.100v supposed to be connected from to pins on both of the BJTs as it looks? But it looks like it’s barely contacting one pin of the BJT the inductor is connected to ground. You can see in pic what I am talking about. Was the opposite inductor pin purposely attached to pins on both BJTs as it kinda looks or was it a quick job and the solder bled onto the other BJT as it also kinda looks like?

Any help or advise greatly appreciated, I’ll post more on physical board repair and other damage if I find any as I go through it. I only have JB weld on hand which it says it’s not electrically conductive and actually electrically insulative so going to use that. But ya this is a weird one for me, I only have maybe 10 boards Max under my belt and this is the first fine coming across an “engineering mod”.

Thx 🖖🏼

You can see the inductor in 1st pic, and the 2 pins it’s obviously supposed to contact, but is it supposed to contact the pin of the BJT the inductor is connected to via ground as well?

2nd picture is of damage, 3rd picture is the only one I could find that shows the area Undamaged, looks to me the rods just connect to that trace correct? There’s no trace on opposite side of board in that area.

Login to view embedded media

I'm working on a Carver M-4.0T power amp that I inherited, and I know nothing of its history other than it's in very clean condition and that it's one of the last revisions with the charcoal faceplate. It had not been turned on in years.

I did a safe power up and found that it was basically working, at which point I started checking for more subtle problems or time bombs. I found a number of smaller electrolytic capacitors on the boards on their way out with rising ESR, so I'm replacing those. The +/-11.4V supply caps were cooked by resistors beneath them, and the 3.3uF 160V caps showed what looked like leakage around their leads.

Last night, doing careful checks with the amp at idle, I discovered that two of the power supply rail steering diodes are shorted -- no diode drop across them. These are the diodes that prevent the higher voltage power rails from dumping into the lower voltage rails during rail switching. One is D28 in the Left channel, on the +67V supply, and the other is D29 in the Right channel on the +31V supply.

Finding two of these shorted makes me consider if these were under-spec'd parts (3A @ 200V). The originals are MR852 rectifiers, which were fast at the time in 1989, but not that fast anymore. I'm looking at the Vishay MUR420, which is officially rated 4A, but, in the datasheet, rated 6A at lower temperatures. It's also a lot faster than the now-obsolete MR852 with max recovery time of 35ns vs. 200ns with the older part. Discussions of Class G amps I've read elsewhere say you want fast diodes here to minimize power supply rail coupling, for obvious reasons.

You can get 6A fast rectifiers, but they are large enough to start interfering with other components on the boards.

Does the Vishay MUR420 sound like a good choice? I'm mainly a tube amp guy, so I'm not as confident with sand-state devices. Thanks in advance for any help.

On you Amp Camp?

On your reflow oven?

On your laptop?

Yes, all of those and more...

GONE...


Retiring and moving. These two power amp boards (A/W115-1022 Rev F) were working and pulled from my Marantz 1200 integrated amplifier, serial number 4490.

The reason I pulled them out of the amplifier was because I installed two homemade Leach Amp boards in their place.

This Marantz 1200 got me back into the audio hobby back in the early 2000 timeframe when one of my Polk Audio RTA-12 speaker drivers shorted and caused one channel to fritz out. The boards have been soldered several times through the years. I've learned lifted traces, 1970s era transistors and components are not rebuildable/replacable an infinite number of times. There are germanium diodes on the pre-driver transistor circuit, lots of old and slow transistors. That's what made me convert to the Leach Amp boards.

Boards are for sale for $200 each plus actual shipping cost, shipped from 87123.

I also have 20 each of the MJ15001G and 20 each of the MJ15004G power transistors for sale. They are brand new in the packaging as received from Digikey and Mouser. I prefer to sell them as a lot of 20 of each type rather than individually. Price is $85 per lot, plus actual shipping. This is about half the price of what Digikey, Mouser, Newark sells them for if they have them in stock. I've checked Hfe on some of them, otherwise they are brand new and unused.

I've also attached a list of other new in the package transistors I have. I would like to sell them in the quantities listed for half the price they cost from the vendors.

Respond to this post if interested. I'll leave these items on here until Friday, April 8th.

Hey guys,

I was running a Mac OS for like 10 years on a hackintosh -- Intel 3770 with a motherboard that had SPDIF out.

I could play 24/96 to my FIIO DAC via S/PDIF all these years.

Unfortunately, my 3770 system died and I had to replace it. I went with Mac Mini M1 since it provides so much power and is so quiet at an affordable.. I got for $649. However, the Mac Mini M1 does not have an S/PDIF output. I am currently running my audio out of the Mac Mini M1 to my SAMSUNG TV via HDMI, then my Samsung TV's S/PDIF output runs into my FIIO DAC.

Also unfornately the SAMSUNG HDMI to SPDIF connection limits the sample rate to 48khz, although it's 24 bit.

I would like my chipamp / first watt buffer preamp to be able to play 24/192. (the amp and preamp are both superb and diy.. i think it'll last me the rest of my life)

Any suggestions on how I should get this Mac Mini M1 audio output to my system at this 24/192? Perhaps something that sounds amazing and is affordable? This FIIO only cost me like $30 and it wasn't bad at all.. I made some mods to it with linear power supply and some extra capacitors etc.

Should I get a USB DAC? Or is there an audiophile wireless solution these days? That way I can connect to my audio system from any device without any loss of quality?

Repairing a Kicker 06 ZX650.4 I just got in, stuck in protect I guess, first thing i do with amps like this is clean them up, bottom was corroded like it sat in salt water, main power trace starting to lift from board, I clean it all up, reattach trade edge that was lifting, amp powers up perfect, waves look great etc, only thing that was off while probing, etc was the JFETs J110 in Q100, Q200, Q300, & Q400.

Spec resistance on them between Gate and Drain is 18ohms, each of these is reading between 8-9ohms, which is spec for J108, J109 is 12phms and J110 is 18ohms.

Amp seems to run perfect, haven’t benched/dyno’d it yet but can’t help but think proper spec JFETs would help that much more, problem is I can’t find them anywhere, I’m looking for exact replacements tho and don’t know of any alternatives.

Anyone know the purpose of these JFETs, and of spec JFETs are advised or if the 8-9ohm is fine, that seems like a huge discrepancy to me, half the ohmage it should be. I’d just replace if I could find them, but I can’t and amp “seems” to run perfect as is.

any advice greatly appreciated 🖖🏼

No longer for sale.

I'd rather keep it than put up with imbecilic remarks.

Hi, just registered here. Some background - I'm retired, worked in the microcomputer field most of my professional life, now returning to the magic of tubes. I build a fair amount of simple ham equipment with tubes, and recently I built a stereo amp with a pair of 6JE8s driving (do I dare type it?) Radio Shack 70V line transformers as output transformers. It all sounds much better than it should to my retired ears. Now I'm thinking about how to improve that amplifier, and what I might build next using the tube stash I have, which includes 5670 and 5965 dual triodes, lots of triode-pentode types, 5763 and 6CL6 pentodes (OK, the 5763 is a beam power tube), and a batch of 7C5s. Also various dissimilar pentode compactrons, and lots of other tubes, most of which are intended more for RF use. All I have going for me is a fair understanding how how tubes work, and a very nice scope. 🙂 I am pretty determined to just have fun with the tubes I have, but clearly I have to spend some money on OP transformers at a minimum. My question is, is such bottom-end equipment a suitable topic of discussion here? Thanks!

Started working on this before xmas but found a transistor blown (Q430) so had to wait for the parts-condition dim light tester on

issue +24v on right speaker terminal

so far as attached drawing
-no voltage on Q420 so checked R456 was open circuit-replaced
Q420-faulty-replaced-dim light tester now off
R470-tested one leg lifted-ok
R476-tested one leg lifted-ok
with both lifted at the same time-still 24v on terminal
zener's D432 and D434 one leg lifted on each at the same time-still 24v on terminal
R516-tested one leg lifted-ok has 1.5v one side 24v the other

i cant see where else i would get 24v from? something ive missed maybe?

For sale, multi-tap transformer.

Primary side: 220Vac (will work fine on 230Vac)

Secondary side:
0-20-25-30-40-50-60V
3A max, 180VA

Never been used, just for some testing.
Ideal as a testing/lab power supply.

price 20 euro excl shipping.

Wavelets....as per this article.. Signal Aligning Using Wavelets

Surprisingly repeatable measurements for low frequencies, that normally drive us crazy trying to nail down timing/phase at xover.

Works great with Arta...just like the article says 🙂

How to DIY your brain 😱 😱

DIY tDCS

Hey, everybody!

Simple question (I think--but you know how that goes sometimes):

All things being equal between these two enclosures (same airspace, same port length, same construction, same vehicle, etc.), which one is preferable (ports in red)--(a) or (b)? They'll be facing the rear of a hatchback, in case that's relevant.

Or would you expect their sound/output to be identical? I imagine they would be identical, but I couldn't help but wonder if the two ports together in the center (b) might have turbulence or some other combined effect that they wouldn't have in (a). Or maybe they would theoretically, but it wouldn't be audible or otherwise detectable.

Hoping someone with more experience than I might weigh in. Thanks so much!

Hi all!

I was interested in experimenting with a Zobel network across the secondary of my 1:20 step-up transformer to address some brightness/coherence issues at high frequencies in my phono setup. I am using a Denon DL-303 MC cartridge (40 Ohm impedance and ~0.20 mV output) and a couple of different SUTs, but mainly a Fidelity Research FRT-3. The output of the SUT goes into a Hagerman Bugle 2 phono preamp.

My questions:

1. To find the cuttoff frequency (Fc) of the Zobel, I am using Fc = 1/(2πRC). What ballpark cutoff frequency (Fc) and values of C and R are good to start with?

From the Sowter website for their 1:20 SUT, they use 9.2kOhms and 330pF which gives an Fm = 52kHz. I've copied this and built a few Zobel networks using an Fm of about 50 kHz, but using capacitance values over 100pF seems too large for my needs. My cursory testing leads me to think that capacitance in the 10-50pF range might be better, but I might be losing some bass response... I'm assuming the objective is to find the smallest value of capacitance and the highest value of resistance that will remove any potential overshoot/ringing issues in the SUT (as per the recommendation an old post I found written by Jensen Technician Dale Roche). Is this reasonable?

2. Is there any need to parallel a resistor to the Zobel network or should one be used only to change the resistive load "seen" by the cartridge?

Sorry for all the questions but I super appreciate any help!! I tried first using just resistive loading across the secondary, but to make things sound balanced, I am losing too much gain and squashing the dynamics. Thanks!!!

offering a full set of 16 PCB‘s for a UGS Muse pramp build.
including salas shunt regultor and PSU.

Price: 220€ + shipping

HI Everyone, Recently I purchased a Nakamichi OMS 7 CD Player from the orginal owner who has never got it serviced since new, this is the orignal OMS 7 not the OMS 7II CD Player. The problem is that there I cannot see any light in the laser and its spins like mad when a cd is placed inside and after few seconds ejects it. No its not the belt underneath as I put the heat shrink on the motor pulley to get better traction also I noted that when you remove the belt and move the gears so the cd compartment is all the way back inside , install the belt with the cd still in place I can see that the cd spins slowly at first there is no light inside the laser head the whole laser assembly move forward toward the cd to come in the center of the cd and then its starts spinning like mad! and after few seconds it will eject the cd . I have tested all the mechanical switches and they tested ok as does the photo switch in the hole in the cd tray. There also a photo switch on the top which shows voltage of 1.1 v on diode setting on the digital meter with the cd player on, I dont know how to test this switch i have shorted it thinking if its not working and if you make a connection with two terminal with a short piece of wire it will make the circuit complete and have also placed a black piece of tape on the clear light sensing area of the photo switch none of these steps have helped solve the problem. I dont have the serivce manual the oms 7 but I do have the service manaul of the oms 7II how much is the difference circuit wise between these two players.

Can someone who had this same problem let me why is there is no light in the laser what to look for and what might be causing the problem mentioned above. All other functions appear to be working the display light up , it accept commands from the wireless remote, green light up in play and pause modes, you can forward the track number from to other numbers from the remote control but not from the buttons on the cd player itself, it in very good condition cosmetically and no one has ever worked on it. Also like to know what color of the light will be if we can get the laser to work again will it be red or green. My email to send copy of service manaul is salihingoro@gmail.com. Any kind help to get this great cd player working again will be GREATLY APPRECIATED! THANKS! Sikander

When browsing through old DIY articles, I found one interesting topology,
that seems was never built, at least not on this forum.
Here is a link to EETimes article "Samuel Groner New Topology",
unfortunately, only part 3 is readable (earlier parts come up with no images),
but never the less, this is the most important part that shows actual schematic of a (headphones ?) pre-amp.
Not sure if this material is copyrighted or not, so I'm not attaching it here.
I think Groner's article was also published in "Linear Audio".

This Groner topology can deliver very high slew rates (over 200 V/us), and very low Thd.
I tried to incorporate this design into a power amp, and to simplify the task, I used op-amp in the input stage,
instead of LTP with current mirror (as in the original design).
Also, increasing current from 1mA to 2mA in the next stage (Q11/Q12) seems to improve stability.
Sim results look good, but one thing that needs improvement for sure, is clipping behavior.
Any suggestions how to do that? Sim file attached.

Update April 2022:
Actual build of the amp, and revised schematic are in post #10

Two toroidal transformers by Amplimo, each with one 230V primary and dual 9V 15A / 0.83A secondaries. The two secondaries can be paralleled for 9V 30VA / 1.66A, or put in series for 18V 15VA / 0.83A. Comes with mounting materials.

New €40 a piece, asking price €50 for the pair excluding shipping from The Netherlands.

Used a little over a year and bought from ringkerntrafo.nl.

Datasheet: https://www.amplimo.nl/images/downloads/ds standardrange/08011.pdf

Hi!!

I am planning to upgrade my headphone tube amp by replacing capacitors and resistors.

I am perfectly capable of soldering, but I don't know how a vacuum tube amplifier works and all the components' functions.

I am curious to know what function do the capacitors have that I marked in green and pink?

I know that the capacitors that I marked with green are 22uF 500V the pink ones I don't really know.

What type of capacitors would you recommend to replace them with? I assume electrolytic are the worst option, right?

Thanks and best regards

Hello.

I have for sell many pcs of used, tested for capacitance and dispassion Siemens capacitors:
All from 60' and 70'.

1. Dual capacitor 2x 1uF 250V MP J/S 10% B25990-A205-K1
Electrode: Metal layer vapor-deposited on side of paper
Impregnation: Hard wax and oil
size 33x26x19mm






2. Dual capacitor 0,3uF + 0,4uF 160V MP J/S 10% B21990-A0704-G1
Electrode: Metal layer vapor-deposited on side of paper
Impregnation: Hard wax and oil
size 33x26x19mm




Price for 1pcs is 12USD + shipping

Payment via Paypal or bank transfer, shipping world wide.

I repair the output and power supply sections.Amp powers up and plays good audio but I can hear some squealing noise coming from the transformer .

Twisting the transformers doesn’t stop the noise.PS FETs on one side of the board gets warm while the other side stays cool.Drive signal look ok but it looks like some frequency interference on the side that is getting warm.

many suggestions?

10v/dv 10/us

I have an Immedia RPM-2 tonearm but need the damping oil. An article by Michael Fremmer indicates that it uses synthetic motor oil, but doesn't specify the viscosity. I've tried to reach Immedia but it appears they may be out of business. Any suggestions will be appreciated.

Hello, can anyone tell me if I can use my PC as a player and a Sony NAS-E300HD Audio Shelf System as an amplifier.
The Sony has a DMPORT, is this a Digital Music Port? If it is do you know what cable I would need and where can I buy one?
Thanks in advance.

Will adding foam lining change the apparent cross sectional area of a tapered transmission line? I am trying to improve 25 year old speaker not build new. It is a "classic" transmission line with a 10 inch driver at one end and a 6 foot line that tapers from 10" x 13.5" to 2.4" x 13.5 inches. One half inch foam would obviously drastically change the cross sectional area if one just calculates the area using the narrowing caused by the foam. But is that the correct way to calculate this? The goal is the improve the cabinet as the folds in the line use less than 1/2 inch MDF. So far bracing has greatly improved the knuckle rap test. The taper goes quickly down to 6" x 13.5" after 6 inches line length and then tapers fairly uniformly there after. I am thinking of using 1/2 inch foam on only one side of the line for the first two feet of the line which is about 3.6 inches at it's narrowest. The crossover to ESL panels is at 172Hz.

Recently I purchased replacement caps for the analogue output section of my Pioneer cd player which called for 100uf/ 25v caps. Instead of using the standard two pin caps electrolytic caps (Elna or Cerafine) and because I have had excellent experience with Mundorf's 4-pin power supply caps in power supplies, I decided to swap out the cd player caps with the Mundorf's (the Mundorf's were rated for 100uf @100v) . I asked Mundorf about this idea and they did not recommend it because they said the caps would "break". I asked them to explain, but nothing came back.
I decided to do it any way.
With the correct wiring for these special (and expensive) caps, I installed them and as soon as I turned on the player I heard the wonder of these caps. They really are something special and I loved them for about a month. Then the left channel failed: it started with intermittent popping, and eventually that channel failed completely.
So my question is this to those might know (since Mundorf isn't saying): what is it about a/c which makes these caps incompatible with any thing but d/c? Why can they not be used for a/c or in any output section? Would over-rating the voltage even more help them last longer?
Thanks in advance.

Hi, just bought a DacMagic to play around with, anyone know how to actually open this thing? I've only had it a few days so I'm reluctant to be too keen, I removed the 6 chassis screws from the back panel which seems to have made no difference, HELP!

RC 😕

Best budget (400Eur/pc max) compression driver May 2020? Suggestions, please.

There are certainly some new models available. My budget is 400 Eur/piece maximum. Currently I have a pair of Beyma CP385Nds and BC DE500s. I really like the integrated driver of Beyma 12XA30. I would like to have extension as high as possible and as low as possible for HiFi application and high sensitivity. 1.2 kHz or lower. Exit size does not matter. It will be used with a midbass and bass horn or in a synergy style horn.

I scored cheaply some Altec 511b horns. Since i cannot find easily Altec drivers here in Europe, I wonder if somebody had some experience with any modern era 1" compression drivers and these horns?
I've found on audiokarma there had been some success with BMS 4550 and Eminence PSD2002. Any luck with some other driver? I know it is an old horn, and maybe not so hi-fi by today merits, but I would like to give them a try. I plan to use Hypex amp with DSP and cross it over to a 15".
Thanks in advance!

I have been considering a few options for a PC desktop speaker. I like small FR drivers for such an application, but was looking to mitigate a couple of possible issues.

1. Desktop bounce; I don't know how much of an issue this actually is, but if using smaller drivers, 4" and below, their greater midrange dispersion may comb-filter with the reflection to an extent where addressing it could be worthwhile.
2. A "hot" top-end; often found on such drivers, where the upper kHz range sees a rise in response up to the driver's HF roll-off. This can help balance the in-room power-response if listened to with some distance and off-axis, but for nearfield on-axis use, it can be a bit much in some cases.
3. Baffle-step; nothing new, but a typical 1.5-way likely offers too much compensation at 6dB, especially for desktop use with a wall behind the speakers.

I was initially thinking of a 2-driver array to reduce the vertical pattern and address issue 1. With the speaker elevated or angled correctly, it's easy to aim it at your ears' height while conserving a wide horizontal sweet-spot.

As to issue 2, what if we simply rolled-off one driver around the frequency where the rise in response happens? By 8-10kHz, a single driver's beam should already be narrowing, even for a 3", so that it does not make the array moot for the desktop bounce issue described above.

Finally for issue 3, the need for BSC depends on taste and bass alignment. For several reasons, I would not go as far as adding 2 additional drivers to make a 4-driver 1.5-way. What if we only added one extra driver? It would provide partial BSC, hopefully in a manner complimentary to the bass alignment and speaker location.

The driver playing fullrange (A) and the one rolled-off in the 8kHz or so region (B) would naturally be arrayed vertically, most likely as close as possible to each other, or spaced so as to adjust the vertical pattern. The BSC driver could be placed anywhere on the enclosure really. I would possibly make a triangle, with the BSC driver on side, mid-height, of the two "main" drivers, just because it would look cool. 🙂

I see this being useful with drivers such as the Tymphany TC9/TG9, which do seem to have a rise up high and are affordable enough to buy 6 of easily. I have never worked with them or measured them myself though.

The one awkward thing might be wiring and impedance. It would also depend on the used driver's own impedance, 4-8-16 ohm. One could wire in series with bypass capacitors on two drivers, or in parallel with series inductors on two drivers. I'm wishfully thinking first-order electrical roll-off should be enough for both "steps", but this would be a case-by-case ultimately IMO, particularly for the HF step. The impedance response of a complete speaker will likely range from 4 to 12+ ohm nominally, Le notwithstanding. SS amplifiers should not mind if rated for the lowest impedance range.

Does this make sense and could it be worthwhile? Is there anything obvious I overlooked? Is anybody readying a straight-jacket?

I have a larger project for a multi-amp 4 way system and I want to design the best 4 way active crossover filter possible, and keep it buildable as a DIY project, so I want to avoid any SMT type of stuff. Although careful choice of opamps can allow 2 versions of PCBs made, one through-hole and the other could be SMT.

I have all my speakers made and I plan to have a kind of short rack on wheels to house all the power amps, the crossover and all the electronics needed, including a micro-controller based management of the whole thing to automate it so no human intervention is needed on the rack itself, not even to turn it off.

The type of filter chosen is Linkwitz-Riley 24db/oct, making use of all-pass filters to correct the phase differences.

The tentative crossover frequencies chosen (for now) are:

150hz
1.5khz
8khz

Certain things remain to be debated, as far as eventual additional adjustable delays on some bands to compensate for physical alignments of speakers. My speakers are adjustable, as each of the 4 ways is in its own cabinet and they are on top of each other, thus can be physically adjusted, to a point. But perhaps having an extra adjustable delay to correct for some of the physical alignment that can't practically be made, could be useful.

The input needs to be balanced, to allow for long signal cables, while the amp racks would be positioned very close to the speakers, to minimize the speaker cable lengths. I expect the longest power cable length not to exceed about 2m, probably even less, at least for the tweeters, that are way on top of everything else. The bass power cables might not even be much longer than about 1m.

Sorry for the us based diyers, as I work only in metric 😀

Attaching a rough synoptic of the crossover.

Enjoy. Since it is public domain already... 🙂

WCPS v2.1 pcb
A Whammy style psu, made from gerbers I found on here. I dont seem to be able to find the post anymore since the forum migration.
I had 5 of these made in my last JLPCB order. A bit more costly due to over 100mm long.

4 available

£4.5 UK
£8.50 ROW

This thread is for discussions about the F5 clone boards. For more information on this product, please see the product page below.

• Product Page
• Build Guide
• Schematic (V2 boards)
• Bill of Materials (V2 boards)
• Dimensions (V2 boards)
• V3 board schematic

Threads on diyAudio that relate to this product (If we have missed one, please post it in this thread and we will add it to the list):

• Build Thread: http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier.html
• Build Thread: http://www.diyaudio.com/forums/pass-labs/182723-how-build-f5.html
• Build Thread: http://www.diyaudio.com/forums/pass-labs/188691-illustrated-guide-building-f5.html
• Build Thread: http://www.diyaudio.com/forums/pass-labs/185154-initial-setting-f5-bias-help-please.html
• Listening Impressions: http://www.diyaudio.com/forums/pass-labs/155599-f5-listening-impressions-discussion.html
• Modifications: http://www.diyaudio.com/forums/pass...building-quartet-amps-search-ultimate-f5.html
• Modifications: http://www.diyaudio.com/forums/pass-labs/168040-f5-2sk2013-2sj313.html
• Modifications: http://www.diyaudio.com/forums/pass-labs/182966-f5-low-z-loads.html
• Review: 6moons.com - industry features: Swansong for an ugly duckling

Hello everyone!

Attached is a schematics for inverted LM3886 that uses NE5532 opamp as a buffer and also as a difference amp for the balanced input signals. I am not in a hurry to build this one as it will probably take some time before LM3886 will be back in stock on Mouser.

This schematics is just hypothetical idea on how to combine multiple useful properties of opamps. There are a lot of benefits with inverted LM3886. An input opamp serves dual purpose too that I thought was really cool.

My other way of thinking was to not do balanced input and feed the signal into the inverted input of the NE5532 - in that case both chips will be inverting the signal and it will be in phase on the output. Idk though, is it that important to get output signal that is in phase? img attached

Any thoughts or input will be greatly appreciated.

Hi.I want to build quad405 assembled kit (my friend changed driver transistors and now it seems amps work ) with LLC smps. I will use metal enclosure.Should i isolate the T angle aluminium from the radiators? Radiator will be connected to the case of amp.

Hello,
I wanted to know your opinion about the YXF series from Rubycon.
These are electrolytic, 105°C. Low ESR types... can they be good for PS decoupling (I can get 100uF /50V at low price)?

Cheers

Andrea

This power amplifier is damaged in the power supply part, and the dB performance cannot work now
Need PHILIPS SQ 45 circuit diagram repair manual, who can provide
grateful

Hi friends
Tady, my aging eyes spotted a broken corner on my td-125's plexiglass(?) cover. This is quite a common damage it seems.
I‘m confident that there’s a suitable glue for it, but which one?
Acrylic glues tend to blind the material with the solvent, and I read somewhere elese that epoxi isn’t good either?

Well here we go, this should be interesting.
Left channel main fuse blown, so possibly a transistor fault.
As far as i can make out there are 3 versions of this, with 3 different schematics
first thing, serial number on the back of mine doesnt match with anything but i have a 63v supply so im going to assume at the moment i have a V1 model
The others appear to have a modified supply at 30v
vesions 2 and 3 have opamps, a bit more like the later version 5050

biggest problem now is the board is unmarked at all, so its all going to be tracing from here on with cross referencing the drawing.

I know that resistors exhibit resistance variations with temperature (temperature coefficient), and with voltage across them (voltage coefficient). These change with signal levels, causing the resistor to change value with instantaneous signal level, giving rise to signal distortion. All well documented and quantified.

But are these the only sources of resistor non-linearity? (I consider noise as a separate phenomenon so exclude it here).

Jan

Hi,

I was able to purchase a set of TDA1541A and TDA1541A-S1 single Crown dac chips.
See photo's attached.

New Old Stock (never used!):
6 pieces TDA1541A S1 (8931 and 8805)
2 pieces TDA1541A (8714)

These are from a repair shop in Belgium and have been sitting in their parts stock all the time. They are brand new and genuine, no Chinese over-stamped rubbish.
I have kept some S1 pieces for myself and they are truly amazing!

I also have 4 pieces TDA1541A (8828) from a diy dac board that I purchased from a diy-er that build the pcb's but never got around to finish this project.
I think these are also brand new, the pins however have some normal scratches due to them being pressed into the dac pcb's (not soldered).

The dac chips and pcb's are for sale.
Please PM me for pricing.

Hello, I picked up a pair of the unusual Fostex mg130HR drivers, they seem really nice.

I`m building the recomended enclosure supplied by fostex ( 10.2l BR 62hz port ). Simples.

I love floor standers, not book shelf. Is there a floor stander I can put these drivers into the frugal horn XL for example?

Any advice great fully taken on board.


Thanks you

Hi folks,
I have an Elekit 8600s and was wondering if it is safe or not to switch the impedance switch between the two settings while the amp is on or on and playing music. I don’t want to do anything stupid! Thanks for any hel!
erik

I have a pair of DIY speakers I built from a design from someone that was posted on this site I believe. Some of you may recall what the design was called, but my memory no longer serves me well. They have ribbon tweeters and a Tang-Band driver for the mid-range; I do not recall what woofer it is, I'm sorry. I bought all the components from Solen here in Canada. The colour of the boxes may not to be your liking, but I assure you these are very well built - I built them. They come with two basic metal stands a friend made for me. These are FREE for anyone who lives in the lower mainland of British Columbia, Canada who is able to pick them up from me. My hearing and general health has taken much joy from my life; I hope whomever wants these enjoys the music they produce.

Hi All, I’m working on a large sculpture and want to incorporate PCBs glued together for vering looks.

where can I find used PCBs? Thanks in advance.

Hi , I want to start here an open Diskussion which is the better OPV for the composite mode by using with LM3886

I can get both of the types for free. So we do not must diskuss about price and availability.

So only about technical Stuff , advantages, disadvantages.
And which OPV values in particular fit better with the LM3886 in 20k / 1k gain or 10k / 1k for the LM

So please diskuss here what are your opinions

Target Use: The Composite OPV for LM3886 at Vcc +/- 15V or 12V OPV Voltage.

kind regards and happy discussuing

Is there a collection I can buy that is actually original, not remastered?

An old Vector Research. Not much. but is what i have. It Has an 8" down facing driver in a 20 x 13 x 5 inch tall enclosure with 2 cardboard ports on one end. The specs call it a Linear Compliance Woofer with specs of 6 ohms ,90 db, 28 Hz-150 Hz. 25 Watts Min 125 Watts Max. The wiring is set with both channels going into the inputs and outputs going to two satellite speakers.
I want to just use it as a sub and was hoping to just put in a simple crossover and new inputs, but open to ideas. Or should i just wire direct. I have only made one speaker kit so far and hoping to keep it k.i.s.s.
What say ye?

Hi, i wanted to know if there is a good program to simulate frequency responce off multiple drivers ( MTM design horizontal ) and lobing. the reason is because i want a simular responce from all angles wich can't be done perfectly but i'm curious how close i can come! i was thinking about the Kartesian 4 inch driver with a dayton nd28 tweeter crossed over at 2200hz ( the lowest the tweeter can go ). So with a MTM design the center to center off the 4 inch drivers will be 17,6 cm so after 500hz lobing will occur in a certain degree and i want to know if i can calculate this. if it's all the same at every angle i can simply adjust the frequency responce with dsp.

i also can build a standing( vertical ) MTM to solve the problem and with this design i could put the passive radiators on the sides instead of side and back to cancel internal resonances? or at least the uncontrolled vibration off the speaker because off the weight of the passives trowing in different directions...BUT i don't like the standing MTM design ( it looks cheaper to me, as a portable speaker). i also can make a 3 way design like more expensive MTM to solve the lobing issues and even acting like a 1 point source speaker but this will be more difficult and would make the speaker larger.

does someone have tips or suggestions for me, thanks!!

2 x 18NLW9400, 152 liters each closed box (or both in one box of 304 liters) - processing see MathCAD screenshot, next post.
2 x 15MI100, 91 liters each closed box, processing see MathCAD.

NO ANY resonator, filter corner frequency, steep phase decay, helmholtz, etc. between 20Hz and 400Hz -> Transient response at its best - tight controlled bass, group delay minimized. No Booming, no thunder, just pure signal. Absolutely perfect for home theater.
Crossover is done by pure mathematical magic - see MathCAD.
Sensible Excursion distribution of both 15"s vs. both 18"s. So the 15s can go up to 400Hz without bad excursion caused intermodulation.
18s and 15s acoustically 100% in phase where it is most needed.
System level up to 108.75dBSPL undistorted, -3dB at 16.8Hz. (-10dB at 10Hz).
Aiming for below 17Hz may be BEYOND INSANE for music listening, but barely enough for some HT enthusiasts, over at avsforum.com. I am always wondering what kind of investment some guys there are doing to reach below 10Hz at medium SPL. This system is very cheap and light weight (at least in comparison to some avsforum freak systems).
Depending on the Amping used, the system may be below 170kg. Adding decent midrange and compression tweeter, DSP and amping, the whole system may be ~ EUR 6000 for DIY.
Next post is the MathCAD.

Hello all, I’m on a small tube preamp that I have. I’m removing all of the paper/wax caps and placing films. One of the values in the circuit is 2200pF or .0022uF. I have a roughly 250 .0022uF X/Y rated caps on hand so I’d like to use them as I have a lifetime supply lol. Would an X/Y rated cap function as a non safety cap in that location? It has nothing to do with the AC line, it actually connects to the volume pot. Just want to make sure it’ll work correctly.


Thank you,

Who loves their Allo Pi plus xyz? I am having trouble making it work and am about ready to send it along. Not great support for an old fart that's not to tech savy and I am not looking to get 3 college credits in the process. Am I going to be missing out? Seemed like a nice idea but I'm frustrated and pretty pissy by now.

Hi Everyone,

I'm not sure whether this is really "Pass Labs" enough to post in this forum, but here goes anyway.

Tombo56 has a thread about his awesome input buffer (https://www.diyaudio.com/community/...ludef-sissysit-and-similar-amplifiers.382345/) and as I posted there I've made a pair and am trying them out in a (very) temporary chassis. I like them a lot, and need to fix them up in a more permanent home. A friend was throwing out his old Sony TA-S7 integrated amp, which he recently replaced because it is giving trouble (outputs cut in and out, volume sometimes suddenly jumps to full in one channel... maybe other things too...) and I rescued it from going to recycling. Initially I thought I'd have a go at fixing it (although I don't think I'd actually use it if it was working) and then thought alternatively I could maybe salvage some parts from it, and perhaps use the chassis as a home for the buffer pre.

Opening it up I found that there is a toroidal transformer, with a nice housing. It looks like the main output is +/- 18 Vac, although I'm not 100% certain I've measured the only secondary winding, since some parts of the power supply section aren't very visiv=ble, and I haven't taken it apart yet. Fiddling around a bit I found that all the remote control functioning works just fine (with a universal remote) with some of the audio circuitry disconnected, and apparently the relays switching the inputs work just fine with the pushbuttons (although so far I can't get them to work on the remote). This led me to wonder whether I could take out the power amp section and most of the preamp section, and simply build tombo's buffer into the case, using the PSU, relay outputs and remote control functions. This would create a sort of "Franken-buffer" preamp, with remote control functionality, and the really low THD and nice sound. (Physically a fair bit bigger than really necessary, of course.) The PSU would probably need a voltage drop (since I built the buffers for _/0 15V, but that's no big deal, and there would be plenty of space in the chassis to do it.

I've posted a couple of photos of the Sony below. One or two small boards have been removed for visibility.

So is it a shame to sacrifice an amp that could maybe be repaired? It seems it was well-regarded when new, but I doubt it's worth any great amount of $$ now, even fixed. Anyone have thoughts on whether the Franken-project is a good idea?

Best

Nigel

This is a little project of mine, based on some modules i made for someone i know who had noise issues with AC heating in his 813PP amplifier.

The original design specifications called for a module that was capable of making 10VDC 5A out of 10VAC with optional soft start and very low noise.

The modules use the off the shelf "Saligny" rectifier boards. https://evotronix.eu/main/

I have redesigned the original design to exclude SMD components.

The controller is a MIC5156YM and the FET is a IXTH80N075L2 for absolute reliability.

I will be posting gerbers in this thread once im finished with the redesign.

Hi,

When you listen to typical 2 channel setup, regardless speakers size, be it towers or small bookshelf speakers, the low end could be 20Hz-80Hz.

If the smaller speaker cannot play anything lower than 80Hz by design, how would it get damaged?

Or does this only apply to home theater system where you set speakers to Large for full range but speakers can only gown down to 80Hz?

I thought anything below the 80Hz, the speakers just cannot play it due to the crossover cutting off those lower end frequencies?