I am not able to find explanations of Panasonic's date codes for their electrolytic capacitors that match what I am seeing on a recent batch of various caps.

It is not a simple YYWW like Nichicon uses. Have searched here and AudioKarma, and googled....

Does anybody know how to read their date code?

I have for sale LM3886 chipamp boards + psu boards.

15EUR

Payment by paypall+papall fee+ shipping.

I need assistance troubleshooting this Korean amplifier that runs on LM319 and two 74HC02. It's not producing low side drive,it powers up for like 1 second and I get a DC spike on the low side drive before the amp goes into protection.

How do you go about determining the cabinet volume for a seal enclosure. By this I mean, if I want the cabinet to net 35 hz, how do I determine the cabinet size?

I've been working my way through TC's BIB thread and was wondering if Hemp Acoustics was still together. None of the links to their website work and I've only found 2 sites selling their drivers, e-speakers and ebay.

Hi all,

I recently purchased a used Exposure 2010S2 integrated amplifier. Asking for your advice on something I noticed:

The amplifier makes a pop sound (through the speakers) when switching the power on.
However, it looks like there is a relay in it which clicks about 4 seconds after powering the amp on. I would suppose that is the speaker output protection relay, but
what puzzles me is that if I have a source (e.g. the cd player) already active and playing, I can hear music through the speakers
immediately after powering on the amp (no matter if the relay has "clicked" already or not yet).

I own another 2 amplifiers, an Exposure 2010 (a 2000-2001 model) and a Sony TA-FA3ES (a 1995 model).
Both of them have the relay thing which clicks about 4-5 seconds after pushing the power button on, but those would not
play any music before the relay clicks (even if the source is active already). As soon as the relay "click" is heard, only then music would be heard through the speakers.

Given the above, am I looking at a faulty 2010S2 relay or some other faulty component in it?

Hi there!

Has anyone ever built the Emory Cook/Gus Jose "Ultimate Amp" partly described in the attached? Is there any reason to build it now?

I have the rest of the article, the parts list and the schematic if anyone is interested.

Hi. I've not yet built my own speakers, but like the idea of trying it. I stumbled across Mark Audio after seeing a YouTube video about the Pearl Acoustics Sibelius speakers. They are ridiculously expensive for something with no crossover components and drivers at less than £100 a pair. If they are as good as the hype, I like the idea of building my own using the same or similar full range drivers. However, a kit would cost about £600 and the suppliers don't appear to have any demo facilities to listen before deciding if they are any better than my current Mordaunt Short MS908i Avants.

Is there anybody on here within striking distance of Cheshire that would be prepared to let me listen to anything similar that you have built? I'm thinking about either the Pluvia or Alpair 11 MS drivers in either Frugelhorn XL or the Pensil enclosures.

In the absence of any opportunity to listen, can anyone steer me in the right direction? I really like my current speakers but wonder if there is another level of performance out there in terms of retaining the base extension but improving the level of detail and precision of the soundstage?

According to the KJF website, Alpair drivers are superior to the Pluvia's and the mono suspension is a development, but the frequency response graph of the Alpair 11 MS appears to have a heavy dip half way up, well within the audible range. Is that a problem?

If it helps, my amp is a Cambridge Audio Azure and the room I listen in is about the size of a single garage.

Many thanks in advance for any help or advice.

Hi,

After building a few 2-way speakers (which I'm pretty content with) I decided to try to take the leap and try to build a 3-way.
And I'm looking for some feedback on what I believe should be all right.
So after days of trying to find the right drivers that play a little nice together I came up with a system that I believe should work.
My current system will have:

• Woofer: Dayton Audio RS225-4 (8")
• Mid: Dayton Audio RS125-4 (4")
• Tweeter: Dayton Audio TD20F-4

The crossover looks like this:
(Please ignore the shorted / open parts as I was still toying around with values 🙂 )



The FRD Like this:



Impedance:



The only thing I'm not sure about is how to interpet phase in VituixCAD and I'm kinda hoping I've done it right 🙂




The drivers itself will be inside a vented enclosure in which I'll make some compartements (the woofer will be in it's own compartement where the mid and tweeter will be stuck together)

So what do you guys think? Is this all right? Or did I miss something / mess something up?

Any feedback will be greatly appericiated!

The effects of Karlson's reflective system were mentioned in reports from its demonstation at the fall 1954 Hi Fi show K12 introduction and illustrated in the early Karlson "12" brochure as "Aural Optics". (Bose and others referenced the patent)

A "generally cubical"cabinet ("Fig.1") was used in the patent and simplified in construction with its backwave passing over a gap between its slanted baffle and cabinet top. That gap may have been 2 inches high.

Anyhow, in such a structure I think the tight end of the aperture is setting system resonance and that Karlson probably would have not tuned this cubical "K12" higher than 70Hz.

Can it be guesstimated in hornresp and assuming "so", what model would suit?


(wonder how is "sounded"? - it might be a fun bujld)

I have 2 brand new Sjostrom Audio QSXM3 Extreme Phono Preamp pcb boards available. These are bare boards and do not include any other parts or components. $75 each plus shipping. PayPal ok with added transaction fee.

PM me if interested.

For sale
LSK 170 A
LSJ 74 A

Europe

When I return to a thread that I've read before, it goes to the beginning of the thread
instead of where I left off. I couldn't find any setting to change that.

Hi,

I am measuering a bipolar lythic of a loudspeaker in shunt position after a resistor from a bass low pass section...

On a 100uF cap I see there are few difference between the moment where the cap was pulled out of the speaker filter that was in use the day before, and then 24 hours after. The capacitance value droped from around 0,300 uF on each channel after a night rest.

After a 24h rest, the capacitance meter gives after few seconds a 0,1 uF more then few seconds later 0,1 uF more yet ! I assume it is because of the DC charging from the capacitance hand meter. However the 0,300 uF are not recovered in the few seconds when I repeat the measurement.
What is please the acurate value I should keep for the filter calculation please ?

Despite a loudspeaker filter is seing AC, impulse currents, is it safe to say the damping resistor in the filter is acting as a polarising part for few undred nano cause the bipolar cap is after ? Or it is just due to the natural loading and unloading behavior of a cap whatever it ks jn a filtef cir uit and being bipolar in seie with the signal return, i.e. negative pole ?

So what do the filter see ? The cold rested measurement of the ca pvalue or the few hundred nano Farads more of the capwhen the loudspeakers are playing back music ?

I also assume than my cheap tool is more handy for classic non polar cap measurement than bipolar caps ! But the value of the two caps with the two ways of measuring go from 103.00 to 103.3 and 103.4.... and in the filter development setup the few hundred are important enough to be heard. Ok yhe ears will find what is needed qnd I can add for instance a decoupling of what is needed with precise MKP caps, but the questions are more about knowledge curiosity.

Thanks for your testimonials. Cheers.

My douglas@ email went quiet at some point in January. Apparently my mailbox on the server was full. All reset now, apologies for those that weren't able to get ahold of me!

Hey everyone, first of all, i'm sorry for regurgitating this topic.
I'm trying to fix the single ended input on a TPA3116D module i bought to work with my CSR8675.
I have seen other threads, posts and videos on this topic [1][2][3] but none of them were helpful here, because i don't quite understand the single-ended input conversion done on this board. (I'm a total beginner on this stuff)

So my naive approach here was to just remove C2, C3, C1, R4 and R5 and then add some bodge wires to the pads that go directly to pin 4,5,10,11 respectively on the TPA.
However, this didn't entirely work:

• The potentiometer still has some function that i honestly don't quite understand (ideally, i'd just want the TPA to run at about 70% volume and control the gain from the CSR otherwise, because this board also has the incorrect potentiometer installed like almost every other implementation...)
• The left output (pin 10,11) does not work at all and is just extremely noisy when i hook it up to the CSR
• The right output works somewhat (see next point)
• The amp seems to be in a strange state now where it won't power up "warm" (when i switch off my bench supply and switch it back on, it sometimes doesn't turn on, sometimes draws a unexpectedly high amount of current, etc., waiting a bit (presumably for caps to drain) fixes this. (I unknowingly removed some discharge resistor, didn't i? ....)

So basically i'm really confused because i've never done anything like this and could use some help from someone who has seen all these crappy single-ended input boards and can help me out. 😕



1: https://www.diyaudio.com/community/threads/tpa3116-csr8635-idle-noise.310628/page-2
2: Login to view embedded media 3: https://www.simplemedianetworks.com/mods/differential-tpa3116

This old girl will not power up, but is drawing 0Amps and then 1.5A when I apply rem. There is no drive signal to the PS devices nor at the transformer. A TC4027 and TC4011 ICs are on the PS board. I have not really investigated much, still determining repairability.

Is there a schematic for this or similar oldie?

This will be the story of how this sketch.....



.....inspired by this great piece of work (the Linkwitz Orion).....



.....also inspired by some of my own experiments.....





... turned into this ! 🙂

So I'm in the process of refurbishing that 60s made Vidaire Catalina tube amp.

Strangely, there are 3 different types of capacitors there, all carrying the same rating of 0.1uf/400v

Can anyone explain why they used different types of caps while they are all of the same ratings? Is there a specific reason for using different types?

Around each of the 6AN8 tube there is one huge yellow 0.1uf/400v cap, along with two smaller yellow 0.1uf/400v caps.

What new caps exactly should I use at each position? Is the bigger paper cap polarized? it does have a black ring on one side...

The "death cap" is also a 0.1uf/400v, also of a different type. I already removed it but wondering why they are all different?

Also... there's one 3VDC/50uf polarized cap around those 6AN8. A 3v cap on a tube? does it make sense or am I missing anything... can it just be replaced with a 47uf/16v electrolyte?

Thanks!

https://www.fulcrum-acoustic.com/wp-content/uploads/2021/12/Prod-Spec-DF463-v1.pdf
Looks like dual AXI 2050's to me 😛.........?

Needing more money to acoustically improve my listening room, I´m letting go of my Kiseki Blacheart NS. 11 months old, and has played exactly 30 LP´s (kept track).
I´m the only owner, and it was bought directly from the danish distributer. I only have receipt as PDF on e-mail, which can be forwarded to buyer.

Note: This cartridge is quite particular on azimut and VTA settings, so unless you are able to adjust these properly, you might want to look elsewhere.

There´s a used Blackheart for sale on AudioMarkt/Germany for 4000 Euro´s.
I´m letting mine go for 3000 Euro incl. tracked shipping in EU.
Taking PayPal (+ 4%, or the family and friends option). Preferably EU only.

Just moved into a new house, and can´t find my camera, and my cell cam won´t take close ups/macro, so photo is as good as it get´s of the actual unit.

All relevant info is available on WWW. Particularly take note of channel separation and channel balance, which are among the very best 🙂

For a long I am using the Edifier K550 headphone just as my computer audio listening device.
I am now testing this headphone on my latest tube headphone amplifier design to
experience the amplifiers performance with low impedance headphones ranging from 30 Ohms (the K550)
(because it is the only one I have at this moment), to 70 Ohms (the Sennheiser HD25),
(the amplifier can also handle a high impedance headphone like my Sennheiser HD650).
To my very surprise with listening tests, that cheap K550 sounds unexpectedly good both at low and at high frequencies.
And yes, it is personal taste of course. So I decided to purchase another one of that K550 but to my
great disappointment I cannot purchase this type over here in the Netherlands or any other European country.
Or did I overlook something?

hi,
i'm having an issue with the 6.5 speakers, they get a lot of water on them because of poor VW door design and this actually gets a bit in the car when raining.
i've found a special sort of cloth membrane (some poliurethane from a clothing factory) which is 100% waterproof and want to wrap my 6.5 speaker in it, but this material doesn't let air go thru also.
does anyone know or have any idea how the speaker will perform? (material will not make any noise/vibrate it's very soft and has a side which is like a cloth)
i'm interested in what way will the sound be affected? will get worse? will get better mid-bass? the air behind the cone will push the cone back and obtain unwanted sound reprodution?
any idea?
thanks

Dear All,

Please have a critique of my schematic and PCB layout for the Bob Cordell Super Gainclone "TM".

I think the C1A and C2A should go to the main ground. At present I've got it to "Quiet Ground".

Any input is most welcome.

Cheers.

I use a pair of Sony CD players, model CDP-CX350. One of them has a very faint LED display. Can someone tell me if this is something that can be repaired? Sony no longer supply specific Sony parts for this model so simply trying swapping a new display panel is not possible. I was wondering if this is a common problem that can only be rectified by display panel replacement, cleaning or resoldering connections, or replacing a chip or some other component that controls the operation of the display. I don't have the knowledge of how these things work but I do have the skills required to identify and replace an IC or some rogue resistor if someone can point me in the right direction.
Thanks in advance.

i am using 2 4ohm dynaudio 17w75xl drivers in series for a 2 way speaker.
david morison helped me before i tried using winisd. and came up with 10L for closed box volume for 17w75xl
it's a flat curve . id like a little steeper slope so tried smaller volume to boost upper bass frequencies

i am using iso-barik setting on winisd to model the output.
so when using one 4ohm 17w75xl driver in 6 L box I get the same plot
as when using two 4ohm 17w75xl drivers in 3L box. i understand 4ohm driver is more efficient than two 4 ohm paired into an 8ohm.

but shouldn't the box for 2 driver be twice the size of a box for one driver?

so shouldnt two 17w75xl connected in series require a 12L box as opposed to a 3L box

whats the error?

i attached images of winisd results
green graph is a graph of 8ohm polk mw6503 driver i am looking to replace with 2 17w75xl drivers
blue graph is one 17w75xl 4ohm in 7L box(if i put 6L volume it overlaps with 3L graph )
yellow is two 17w75xl 4ohm in series in a 3L box

My car's speakers are currently powered by a four-channel amplifier. I plan to buy a 12-inch subwoofer as well as an amplifier to power it. I've run a 4 gauge wire to the trunk for my existing amp. I'll get a distribution block and connect it using 4 gauge wire, as well as 8 gauge wire from the block to each amp. My question is: how do I determine the fuse size to use? I already have a 60amp fuse for the current amp, and I'm not sure what size fuse I'll need to replace it with. Do I replace my 60 amp fuse with a 120 amp fuse or leave my 60 amp fuse because the new amp will almost certainly require a 60 amp fuse? I believe I only require a single 60 amp fuse, but I'd like to double-check before purchasing anything. Thanks.

I just stumbled across the 6N17B pencil tube and it looks intriguing as a phono preamp input tube as it has fairly high mu and reasonable input capacitance. I suspect that it might also be fairly free of microphonics.

I suppose that these types of tubes might be inconvenient having no base but I suppose perf board could be used. Pencils could be a very interesting subspecies to play with.

I've been doing some driver 'research' in google images and came across a couple of unusual drivers I never expected to see.

I thought it would make a fun thread to collect images and details of unusual or weird drivers.

I'll start with ScanSpeak coaxial that appears to have polystyrene slapped on the front!

https://s3t.it/weirdness/scanspeak-13m-coaxial/



Next we have a grotesque version o the famous ScanSpeak mid-bass.

https://diyspeakers.eu/product/scan-speak-11m-4631g05-gold/



Then I'll add this one because it is such an unusual suspension arrangement, at least it is these days.

I am using the Aurora dsp and am ready to move start creating my own sigma studio design and customize the platform.
what I cannot figure out is how to set the akm adc and dac to 96k sampling rate.

anyone know?

I, like many of you, would like to build my own DACs because I like to build and explore, and also because I am tired of trying to fix the stuff I have and keep up with new USB protocols - I'd like to have the ability to do my own hardware updates.

If I understand correctly, DAC's are generally set up like this:
Digital input interface -> DAC conversion stage -> Analog pre/voltage stage

(And of course a well designed power supply for the whole rig)

Is this correct?

Are there resources out there for me to purchase USB interfaces but build my own I/v, analog, and PSU's? The only resource I'm aware of are the Audio Note kits but there must be more, right?

[Edited and changed I/V to DAC as per iggy's comment below]

I built this as a more fun with shift registers trial DAC a couple years ago and it it still just sounds great with a mild analog filter after it. I wonder if anyone else is playing around with this converter? I cannot kill this thing. Seems to be very well protected PS wise internally.

Hello, my name is omar, i built a tube amp and now i want to add a reverb unit i found. how can i power this clean and hum free? it is going to go into a clone of a bassman 5f6a it is originally from a baldwin organ. I think the transistors are S429-2? cant really find much..but i need the 22+ I would be able to build a ps with its own transformer? HELLP i dont want to screw this up.




that schem is one half of it....it has two springs/circuits....here are pictures of the unit:





I really dont know how to find out about what kind of power supply to build...i dont know how much current should it get? i dont know anything about time variant equations either...well not enough to find out the total power i should give it.....if someone could help me with a ps circuit i could trade for more schematics (knight, bogen, setchell carlson, redd47,) i even have a wurlitzer reverb tank that needs power maybe for sale or trade as well...so whatdoya say?

Hey everyone!
So here’s the scenario I’m trying to simplify. I have multiple audio/video interfaces and all of them run off 12VDC except one that is 9VDC. The space available is small, so versus having to eat up room with an extra wallwart I would love to run a single larger current 12v supply and use either a small step-down buck converter, LDO, or any other suggestions to supply 9v to the single audio interface. The stock 9v power supply is 2A.

Any suggestions? 🙂

Hi All.

Just been given a SCOTT PS 48A 1 direct drive Turntable.
Are these any good?

It ha a cartridge which I haven't been able to identify.
Marked SSM / 5, with 2 circles and 3 parallel lines above the letters.
Any information would be appreciated.

Thanks Cliff

I have four Usher 1001B 10" woofers for sale. These units are new. Parts-Express sells them for US$150. Asking $60 each. Can provide a matched pair. Check the Parts-Express web listing for woofer specs. Contact me directly at audioltd@metrocast.net. Accept PayPal or bank check.

Decided to keep power transformer, although they are big, but they are more quiet than edcor PT.
Choke is still for sale.

Two choke, 6H, ao-21268

$25 per choke + shipping

Hello everyone! I'm Piergiorgio from Italy. Been lurking around for a long time and then finally decided to join the forum!

Good day,

I am having problem with the counterpoint DA11.5 cdp which always shows "error" when reading the CDs. During reading, the CD will spin for a while, stop and then "error" popup after ~10seconds later. I tried with new optical pickup (VAM1202 as I am not able to get VAM1201 over here) but "error" remains there.

Does anyone has the schematic for this DA11.5? I know I can get from the counterpoint's site but it is just too $$$ for me. 🙁

Regards,
Liew

I've read some threads about getting rid of resonance and standing waves

It seems ideal shape would be a sphere with a transmission line

If you are making a rectangular box and have limited machining/carpentry tools, what would be the best thing to do to help with resonance?

Would making side walls in triangle shape help?

Basically imitation of some b&w speakers where left and right wall of the speaker cabinet converge..so a horizontal cross section would look like a triangle more or less.

There doesn’t seem to be any info on this amplifier out on the web, so I’m posting it here for future reference.

This was the first McIntosh car amplifier made, all the ones that came after looked very different. It’s 4x100 watts, .005% THD. Idle current is around 3.5A at 13.8VDC, and it has a rather odd plug for remote turn on. There are actually 4 pins- one is remote not sure what the others are for, but possibly power guard signaling as in the later units.

The plug itself is a pull to release Hirose connector, I was able to figure out the part number in case anyone wants to order one. I just got a pair myself off eBay for around $20, the part number is HR10A-7P-4P.

Hello,

This is my first question although I have been browsing this forum for a long time.

I'm working on a design of a Peak Level Detector in combination with a VU Meter. The VU meter works great, It is proven to be working as intended. The 0dBu is set at 0,775Vrms with a 1kHz sine.
As 'peak' level +3dBu is set with this 1kHz sinus testsignal. When adjusting the Peak Level Detector to +3dBu, the LED turns on. At 0dBu the LED turns off. So it seems the design is working.

When using with music however, I noticed that the LED turns on much earlier than +3dBu. The LED starts to turn on at around -6dBu. The VU meters are working as intended. When checking with a recorded testsignal (1Khz/sinus), and parts of music on the same tape, the VU meter and the Peak work as intended at the part of the testsignal. When music is played the problem is again visible. It seems that with a complex (music)signal the Peak Level Detector turns on to early. Tests have been conducted with a 1Khz square, sawtooth and a triangle. And results ar roughly the same. LED turns on at +3dBu. It depends a little on the type of music is played but in general only with music the LED turns on to early.

I wonder has this to do with the Crest factor? What kind of signal and/or level of testsignal will adjust the Peak detector at the desired +3dBu correctly?

Regards,

Nev

Hi,

Never really posted anything here, but site has been great inspiration for me.

I have around too many drivers lying around from past 10 years of my DIY journey some never even used, so decided to do a bit of a clearout and sell a few drivers.

Got 3 of Scanspeak D2905/970000 tweeters. Only ever used for about 50 hrs in one of my first projects, but could not set them sounding right. Originally bought for front three in home cinema. Will sell at £60 each + postage. Would ideally sell all three together, but might split.

Pair of Scanspeak R2904/70000 - this is brand new never used boxed pair. Bought but never used due to change of plans. This is the pair with silver fronts. Want £275 for a pair plus postage.

Also have brand new pair of Aurum Cantus G2Se ribbon tweeters. This is factory special edition of G2 tweeter which is not available in retail stores and is only sold to manufacturers. Want £175 + postage for this.

All items are available for collection from Manchester. Or can deliver pretty much everywhere in world if you pay postage. Bank transfer prefered, but paypal is possible but cost to be covered by the buyer.

Will also advertise few other cheaper drivers once I get everything sorted and tidied up.

Thanks

I found this set on the bay

3 way Kit EM-i12 Kit made using RTi12 Major Components


3 way Kit EM-i12 Kit made using RTi12 Major Components | eBay

US $249.00
Seems like a great deal?
WO

Hi there!

I 3d printed a port computed with WinISD. Box is 2.83L of internal volume and tuned to 76.44. Port is 32mm x 12mm. I followed suggestions about making a port with the biggest area you can afford in the enclosure leaving a port diameter clearance. I really like the way it sounds, if I compare with the PS95 after getting the recommended passive elements to tame the peaks.

Questions:

• Do you like this rule and if so, does it apply to small speakers? With 5W I get port wind speed = 14.
• Is it better to model to the max wattage you are planning to use and have speed close to 20?
• Is the frequency response acceptable? Can I do better with a speaker this size?

Thanks.

Hi,

I'm looking at extending the bottom range of my system a bit with a sub. This is in a small room (12 square meters ~4m x 3m).

I have 2way speakers I built with Accuton C173 drivers and Mundorf AMT tweeters. 17l vented enclosure. They sound wonderful but sometimes, I little more "oomph" at the low end would be nice.

Amp is tube based 35W. Loud enough for this room.

I figure an active sub is called for that would feed off the speaker connection from the amp (hi-level connection). That needs to happen in a way that doesn't do wired things to the impedance that the amp sees. The speakers have a very well designed impedance lineraziation which works well with the tube amp and I don't want to mess that up. I don't know much about active sub-woofer designs but in theory, it shouldn't be a problem I think as that input would have super high impedance that is totally getting dominated by the impedance of the speakers. But then again, I have not done this before so I'd rather use a prooven design if possible.
Obviously, bringing a solid-state active subwoofer into a tube setup might feel like a bit (or a lot) of blasphemy to some but I think it's a good option in my case. I don't have space in this room for huge full-range speakers so I'm good with mixing whatever gets the job done as long as the quality is right.

Given that the system is of quite high quality, I want the sub to match that and use high a high quality driver and electronics. Using ready-made modules would be OK but I'd rather build the electronics myself so I have some say in parts selection.

With the limited expirience I have, just looking around, I think I'd build a closed box (60l) for a 15" Timphany STW. I think a vented design would be too huge given that this is a small room. I don't need a lot of volume. I'ts just about extending the range of the system into the lower regions while maintaing tightness and definition of the sound.

Rather then figuring this all out on my own (which is fun but also error-prone), if someone knows about an exiting project which has proven itself in practice, I'd rather start with that than building from scratch.

General question about high-level inputs/outputs and crossovers in active subs. Would this be design in such a way that it represents a high-pass to the signal that is going to the main speakers or would it just represent a voltag divider and sit in parallel with the main speakers and then use a low-pass internally when feeding its own output stage that's hooked up to the driver?

Thanks,
Lars

Hello DIY,

My active speakers/ monitors ( Event Opal) , 2 way, with AB amps, started doing something interesting recently.

When powering off, the woofer, on one side/ channel only, moves in then out. Sometimes accompanied by a slight thump.

The other side/ channel, doesn't move much if at all, and is quiet.

This is a new characteristic

What could be going on?

🤔

As I continue cleaning the audiophile closet, I find that I have an as-new Alesis Masterlink ML-9600 that I would like to sell to someone who has a use for such a device. Currently packed in original double box with all accessories. I don't believe that this was used more than a few weeks, then packed away. Here's a review in Stereophile by Michael Fremer. Product Overview Sheet here.

I see these are currently going for $249 to $299 on eBay. I'm fine with $150 if a diyAudio member is interested. PM me for more info.

I don't know if this problem is common across all Nakamichi DR series cassette decks or just in the DR-2 model but here is what I found in one and how I fixed it.
When measuring various aspects of the deck I noticed this harmonic noise comb in the source monitor loop. Not evident in the tape monitor loop. Either because absent, line muted, or tape noise covered.
After examining it I understood the ground-loop's root issue and decided a least intrusive solution. To simply insulate the RCA quad's grounded face plate from the chassis.
I punched a white Post-it paper with a BIC ballpoint using the back of the chassis as template for the RCAs to feed through. It worked... Here are the FFT results.

I believe this fix will prove useful to Nakamichi DR owners. It increases the bass to mid resolution (less grunge noise) in the source loop during the recording process.

Hi members, I am from Sri Lanka and managed to lay my hands on a couple of HB2's that I had been searching for years.

I am missing the harbeth logo on one and would like to lay my hands on one. Also incase I need to replace any components is there a known source?

Kindly help/advice.

Warm regards

Lalith

Anyone know what the maximum recomended operating tempurature of a 5 watt sand/cement/ceramic what ever you call the little white coffin type resistors is??

I am working on another SWR bass amp that failed because the resistors got so hot they melted the solder!!!

These amps use two 5 watt 1100 ohm resistors piggybacked and two 7.5 volt zeners in series to drop the +/- 75V down to +/-15v

I measured over 200 deg F / 100 Deg C right on the resistor body! that seems a little too hot for me!

I also noticed that the flux around the resistor legs where they are soldered together was bubbling!

This really seems like a serious design error if these resistors are running that hot. thats 2 amps now that have failed for the same reason. this one only partially failed. It was exhibiting odd performance fluctuations. sometimes it would run fine, others, it had no power and ran very hot. I found that when one of the resistors would lose contact, the amp would oscillate at full power! NASTY! Luckily we caught the problem before the amp went POOOF!

I have to find a cost effective solution for these things. there just isnt any room in there to mount 10 watt resistors.


Im still working on the pass regulator boards, havent had any time to test them yet however.

Zc

Hello,
I have an Allo volt +D that I want to put in a smaller box and, as I don't use the volume control and it is quite bulky, I want to get rid of it, and ideally substitute it for a two position switch (max. Vol and say 60% vol).
Does anyone know which of the 6 cables I need to short or connect resistors to (in the case of the switch option)?
Thanks a lot in advance.

Has anyone seen anything other than red circuit boards in any of the orion HCCA amplifiers?

I have a Rockford Fosgate R1200-1D. When I enable the amp the power rails power up. +- 50vdc. However the rail voltages doesn't seem to be making to the power transistors. I assume the +/- 50 volts should be showing up on the power transistors also. And oh yea, the blue light is on. Is there a couple of switching transistors that switch the power rails to the power transistors? Does anybody have schematics for this amp, or can tell me where I may be loosing the power lease?

Al
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Quite a few years ago I built three SEAS Idunns using kits and pre-finished cabinets from Madisound. Originally they were uses as LRC in my apartment's home theater setup. Now that I'm in a house, I use two of them in my PC soundsystem while continuing to use one of them as a center channel.

I'm in the process of building some DIYSG Volt coaxials for surrounds and a center channel, which will leave me with a spare Idunn that I can use to experiment with.

My experience with the Idunns has been that I like the sound of the drivers, but the overall tonal balance is a bit bright (especially sitting close to them) and the bass has always been anemic. I never loved them on their own running full range. In my current setup, I have them crossed at 100Hz to a very powerful array of eight 12" sealed subs. I have a high shelf to tame the treble by a few dB. This setup sounds amazing, but the Idunns start to run out of steam a bit earlier than I'd like. They also lack punchiness in the midbass. I'm also just ready to try something a bit different.

The design goal of this system is to be hi-fi for daily listening but with the ability to crank up the bass and get loud when I practice DJing. Trying to have it both ways. The room is small at 11'x11' but treated with some bass traps and absorption panels.

One option is starting over and building entirely new and different speakers from a kit or from scratch. Put that aside. The other option is buying an additional SEAS woofer and going MTM.

My skill level: I've got a measurement mic and Dayton Audio DSP but have only done basic in-room response measurements of my finished system for EQ purposes. I've never done cabinet building or crossover design. I may be willing to dabble in both for this project, but wouldn't mind keeping it simple.

Which leads me to my questions about the SEAS Bragi design.

1. These woofers say they are designed for ported enclosures, but given my subwoofers I have no need for bass extension. Would they perform well as MTMs in a sealed 24L box if I were to reuse the Idunn cabinets with a new baffle (the Idunns being front-ported)? Would the crossover need to be redesigned for this?

2. Assuming I built new 30L cabinets for the Bragi, should I use the SEAS crossover design given my opinions on the Idunn voicing? Are there any issues with the crossover in general that jump out at the experienced designer? I figure if the crossover point and overall topology are good, I can probably tune the tonal balance to taste with my DSP rather than messing around with padding the tweeter or whatever, but if there are bigger issues then perhaps I'd take a stab at a different crossover or run them active (I'd need to purchase an additional amp, but that's ok). Keep in mind that my listening distance is about 5 feet, so driver integration is very important.

Thanks in advance.

I've got a little work cut out for me here. I'm thinking either this amp suffered from reverse polarity, over voltage, or possible just the Pre-amp FET (BUZ11) overheated. Its got a small sync on it. This FET burned the board pretty good but seems the large traces can be easily reconstructed after cut-out. I'm planning on mounting the new single FET to the main heatsync afterward.

SO, I realize theres not much literature out there on these amps so here goes. The amp is using 4 powers supplies, but the power supplies won't start until the one BUZ11 on the Pre-amp board starts. After which, the main PSs supply the two B&O Icepower A1000 modules.

In previously servicing another one of these; I know the amp should power up with the IcePower modules removed. See reference thread a few months ago: Eclipse DA7232 - ICEpower 1000A?

I dont have that other amp any more.

The failed BUZ11 caused some trace lifting on the Pre-amp board, trace also burned up. Also a trace on the main PS board got hot enough to burn the topcoat but seems to be OK.

LM2574M +5.0 P+ is driving the BUZ11 FET. After figuring out the ground trace was required I can observe clean drive signal to the gate of BUZ11.


I'm at the point where I need to cut and then build-up, but I was wondering what D201 is? Its missing and I dont know what it should be. Anode source and Cathode to drain. Is this just a reverse polarity diode? 1n4004? Or perhaps HER105?

The other missing resistor is a 2w 1ohm which happened to be in a parts bag inside the amp.

Photos coming

My apology if this has been asked in the past, tried to search but didn't found anything.

Is there a Russian equivalent for 12AU7? Same pin arrangement and perhaps electrically compatible.

Please bear with me as I'm just learning about valve. Thank you.

~Kecap

One of the amps in this model was damaged; I repaired the PS bjts 2n6488, and ALL caps in this amp. Now one channel has 2.5vDC on it, and the other has -0.6vDC on it. With a speaker load, the amp draws just a few amps of current as it sucks in the speaker just slightly. The channel with 2.5vDC on it has a lot of noise through a test speaker. I replaced the 5532 opamp, and pulled the 5533 opamp to clean under it's pads. I dont have a replacement for the 5533, except I may try swapping the 5533 from the good half of this amp which is actually working just fine.

Good rail, +-18vDC. Good regulated +-14.5vDC.

Nothing seems open, shorted, or anything. Any clues where there might be so much DC on those channels?

The other amp's half, which I also replaced ALL electrolytic caps is working just fine.

My old Technics amplifier went dead. I suspected the power IC SVI3205 may blown.
How can I determine?
I read from a book that checking on-board IC can be done by measure the resistance of the chip's individual connector against the ground (positive & reverse). Take the reading and then verify against the resistance value provided by the manufacturer to determine the IC is bad or not.
Is that work?
However, I can only found the chip diagram from the following website but no resistance value found:

http://www.geocities.com/technicshifi/SVI3206.jpg

Could someone kindly provide me the resistance value I want?

Also, I can't find this SVI3205 IC in digikey.ca. Is any model of STK or LM series IC could replace it? I think it's easy to find and must more cheaper.

Thanks in advance for your kind assistance.

Hi folks. I have a project in mind that requires skills beyond my scope.
I need to design and 3d print a waveguide but i have no idea where to start. I can however draw a profile of what I need, a 2d profile I guess you could call it. If i supply this drawing is it possible that someone would be able to convert it into a usable file for a 3d printing company to use?
Cheers.

Buy valvular Copland CTA-505 in very good condition both exterior and functional, the 6550 valves were changed in August 2013

The price is 1150 € + Shipping

Technical Data
Form Tube power amplifier Class A Triode operation
Effective output At the time of PENTODE connection: 67W+67W
At the time of TRIODE connection: 35W+35W
THD Below 0.02% (1kHz/1W)
Below 0.8% (1kHz/60W)
Frequency response 5Hz - -80kHz +/- 3 dB
Output bandwidth 8Hz - -45kHz 3 dB
Signal to noise ratio 102dB (IHF / input short-circuit)
Input sensitivity 1.5V
Input impedance 250kohm
Output load impedance 4 Ohms or 8 Ohms (minus community, plus connection substitute)
Negative feedback 16dB
The phase between input and output Right phase
Valves employed Voltage magnification and phase inversion: 12AX7A x 2 - 12AU7 x 2 - 12AT7 x 1
Electric-power magnification: 6550A SVETLANA x 4 set
Power consumption 185W (Electrical Appliance and Material Control Law)
Dimensions Width 430 mm x Height 175 mm x Depth 375 mm
Weight 25kg

I've had good success using these inexpensive DC-DC converters for vacuum tube B+ for a couple of years, but recently had two failures. A previous thread here reverse-engineering the circuit was very helpful but I wonder if a more complete schematic is available, as a couple of links are no longer working.

I'm going to do more measurements but have one of the units working again after replacing the FET. The RU7088 used is a 65 volt device and I'm going to see how close to that limit the drain voltage gets with the supply cranked up to full voltage, as I was had done. Another FET tested good using a DMM but still would not work in the board, although an IRF510 replacement does.

I also found the half-wave rectifier diode was leaky causing a low impedance at the output, and am puzzled about how that happened and whether it could have loaded the secondary enough to cause the FET to fail. I would have expected the overcurrent protection to kick in but some boards have a metal shorting bar in place of the current sense resistor.

I just thought I'd ask to see if anyone has experienced similar failures with these inexpensive boards. I'm also interested in any open sourced 3-400 volt DC-DC or line operated switchers good for 100mA for vacuum tube projects if anyone has suggestions (ideally using off-the-shelf magnetics).

Thanks, Bob

Hi
Im not sure this is the right place to ask, but I am frustrated and desparated.. so hopefully some experts can give me some ideal of how to fix this amp.
I have a Rotel RMB-1095 amplifier (produced around 2003). It is a 5 channels, 200w/channel. I only connected and used 2 front channels (L,R) at lower volume (20-25% power). The amp worked well except it RANDOMLY went into protection mode!! Sometime it was 1 hour into the movies, sometime 3,4 hrs, or even every 2-3 days (RANDOMLY, unpredictable!!). When the protection mode kicked in, all 5 LED (for 5 channels) turned on, and sound disappeared (even though I only connected/used 2 front channels!!). As soon as I reset the power (On/Off), the unit worked well again until the next shut down! This unit run quite hot, but I placed 2 computer fans on top cover, so overheat should not be a problem. I tried to isolate the issue and did an experiment:
1. Connected power + signal input + speakers ...... unit shut down
2. Connected power + signal input. DISCONNECTED speakers .... unit shut down.
3. Connected only power. DISCONNECTED signal inputs ...... unit would run perfect for weeks, NO protection mode kicked in!!

Also noted, I have this same setup of speakers, cables, signal input (Denon AVR) for years with other amps... all worked perfect, so we can eliminate the speakers and cables factors.

I sent the amp to Rotel AUTHORIZED service center. Per Rotel's service bulletin, he replaced the 5 resistors (which supposed to be under voltage..etc..), rebuilt "protection power supply" board. He stated that the unit tested and worked fine. As soon as I took it home, the same protection circuit triggered again (no improvement at all!!). I had since brought it back to Rotel's technician 3 times, and he could not anything wrong with it!!

I am so frustrated and tired with this amp. I had invested more than $1500 in to this, hoping I can keep it for another 10 years.... But the protection circuit trigger drove me nut!!. I have invested too much to justify throwing it away!!. Can someone have any idea what to look for? where should I check out? which components might be the issue?? Or even any local shop that is capable of fixing these type of issues?? I am from Orange County, near Los Angeles area... dont mind driving around 100 miles radius if there is somebody around here that know how to fix it. Thank you

I was experimenting with running different preamps into a Hypex NCore amplifier. I modified the Hypex buffer to create a unity gain buffer so I have the right gain structure, by removing Rg shown here. Works great!

One preamp I have is singled ended tube, AC coupled through a cap, Output Z of 1500 Ohms. If I measure the frequency response into 100K ohms, I get a LF rolloff of almost 5 db (I should increase the cap size - I think its 1or 2 uF).

When I run this preamp into the Hypex, and measure at the output of the preamp + amp, the rolloff is completely gone. It's now flat to 20 Hz. Great!!

The Hypex has has an input impedance of 47K, but yet it behaves like a very light load. THD is even down as well. I tried reading it about it, and I see that the feedback of the instrumentation amplifier buffer somehow simulates a high impedance. But I don't quite get it. Could someone explain how this works? And also, if it doesn't behave like a 47K load, why is the input R listed that way? To everyone trying to bypass buffers of amps, more transparency blah blah, just take a look at the benefits! See pic below.

Does anyone have any experience using a choke-to-ground on the cathode instead of a cap/resistor to ground?
I tried it twice. In both cases the current of the choke matched the current going through the tube so that it did not overheat and I made up the resistance required by the original cap/resistor combo by adding a resistor in series to choke. Bias was also correct.
I have tried it twice using two different chokes: one Ei and one toroid and they sounded the same. Both had a similar effect with a vocal and piano cd: the piano came out clear and sharp as usual; the voice was as if it was out of phase with itself: much quieter, recessed and barely audible relative to the piano.
What gives?

Both are in great condition and work fine make a reasonable offer or trade for a pair of nice 12s.

Hi

I have gradually been building a 1979 vintage 'Sony System A' (replicating what my brother and I shared as teenagers) for my 20 yr old son, and have the turntable (PST15), Tuner (STA30L) and Amp (TAF30), and it sounds great (at moment using speakers from a 20 year old Technics mini system).

I was wondering if anyone can tell me what the correct cable would be to connect the Amp to the tuner ( I am currently using a twin cable (apologies I do not know the correct name) that came with a Sony video camera I brought in 1997.

I also need to find an aerial to use as I cannot get a very good signal using the built-in (AM ?) aerial at the back if the tuner. Again I'd be grateful if anyone can offer some advice.

Lastly I am looking for the System A tape deck and tuner, so any advice on what to look for/pitfalls to avoid for would be much appreciated.

Thanks in advance

Regards
ferric

Hello from Perth Australia... just trying to set up a first post
.

Hello.

I have just joined this community and wanted to say hello.

I first appreciated audio / hifi when my parents saved up and brought my brother and I a Sony 'System A 'in 1979, which wet got a lot of use and pleasure from.

Unfortunately after we have both moved out of the family home 20 years later the hifi was unused in our old bedroom, and my father eventually disposed of it when he moved out.

However I have gradually been building it up from Ebay and have the turntable (PST15), Tuner (STA30L) and Amp (TAF30), and it sounds great (at the moment using speakers from a 20 year old Technics mini system).

I have joined to learn how I can identify how to maintain the system and find the best second hand parts I need (Tape Deck and speakers) and what pitfalls to avoid.

I am also interested in developing some knowledge in sound recording.

Regards
ferric

I have several days now the status "operational delay" at CDG airport for shipping on my 4U Deluxe case.

Are FedEx operational delays common when trying to get a chassis shipped to the US?

For beer money, or free:
2x Kenwood TA2030
2x Kenwood TA2040
If preferred with the weird 2-in-1 resistors for setting bias. Can also remove the uPC1237H protection IC (but only for a while, amp will be going somewhere else).

Removed from a "working" amplifier. All switches were totally crap on this amplifier. Normally the signal would not get through, but with all switches soldered through it would work. However, I decided to put something else in, because it gave off a high-pitched squeal sometimes. I am not sure if this is due to the crappy front-end or because the chips are giving up. (There were technics chips where the internal carbon tracks would deteriorate).

Thus: free to a good home, but preferably for a little beer money 😀
Shipping from europe.

I ordered a center channel upgrade for crossovers and the speaker has a big null in the crossover range of 200hz if I wire all speakers in phase.
The speaker has two woofers wired in parallel crossed at 200hz with a big inductor only. So first order I think? They are two 6.5” drivers. The midrange is a 4 inch so distance is a bit compared to the 6.5’s

The tweeter and woofer measure very good together all ran through their crossovers and connected all positive to positive negative to negative. I flipped the + and - from the parallel woofers after the crossover so the negative goes to the positive of the branch and the negative going to the positive of the branch. This fixed the null in the 200hz range.

so does that mean the woofers are out of phase with the midrange? Should I flip polarity on the speaker when I run the software for my receiver for the sub to match up?

evening.I had just finished repairing one of these today and got it all set up, but when i went to test it, and depressed the SLC switch it all went a bit haywire and the lamp came on relay bright.
so my first thoughts as always was to check the immediate surrounding components but the 4 immediate resitors are all good(circled in red)
Now its only one channel and the lamp is only on with fuse F6 in place
what could have happened here, im not familiar with this feature
whats odd though is i have about +2v on each channel, not just the apparent faulty one.

any help would be great while i plod on.

many thanks

I would like to build a choke input power supply that calls for a 3A choke
with a critical inductance of 10 mh. Would it be ok to use a inductor just
rated for 2A and 70 mh. Oh I realize it will start to saturate but even if it
did lose 75 % of it's inductance that would still be above the critical value.
But would the 3 A likely harm it ?

I bought a couple of packs of machined PCB turrets but haven't found the right tool or technique to support them when setting the tail. The turrets collapse when I try to set the rivet.

I was expecting the outside diameter of the wire supports to be smaller than the base OD to allow a sleeve tool to transfer the reaction force to the base, but these ones have an equal OD.



For scale, the stem at the bottom is 2mm long.

Does anyone know of the correct tool for this type of turret?