I'm making TL cabinets for Alpair 10.3. I routed holes according to the spec which says 139mm. When I tried to test fit the driver and pre drill mounting holes I realised that there is too little of meat left and I could've safely make driver holes smaller in diameter. And It's too late to redo it. I'm using 18mm MDF with 10mm cutout to fit drivers flush. Any ideas how to strengthen this area? My first idea is to put blobs of thick Poxipol epoxy under screws and redrill. Or glue pieces of 6mm MDF with the same compound.

So I've been using this circuit but I'm getting varying readings.

It sort of stabilizes and then Erin I go up/down again.

I've searched the net for an alternative circuit and came across LCR meter.

Thoughts on these devices?

Thanks

Any abandoned FC-100 amp projects out there? I’m looking for PCBs, components (especially the various matched transistors that are required) and any other relevant parts.

Hi folks,

I have busy lately and I have built some PCBs with TPS7A4700 regulator. This is a low noise regulator with output capable of 1A.

Specs
Input voltage range: 2.2V to 25V AC, 3V to 36V DC
Output voltage range: 1.4V to 20.5V DC
Output voltage noise: 4uVrms (10Hz, 100kHz)
Dropout voltage: 350mV at 1A
Output current: 1A (with sifficent heatsink)

More details
-Output voltage is configurable via solder jumpers
-Sensing pins for better performance, DUAL PCB has sensing for positive voltage only, SINGLE PCB has sensing for positive and negative voltage, if not used they can be bridged to output via solder jumpers
-DUAL PCB can be easily configured to operate in symmetrical or single voltage output (solder jumper), transformer with dual secondary windings is a must when you use symmetrical output
-SINGLE PCB can have better capacitor in sensing circuit, there is space for 5mm lead spacing capacitor (for example: Wima 1uF/63V PET)
-DUAL PCB uses bridge rectifier, SINGLE PCB uses rectifying diodes to convert AC voltage to DC voltage.
-user can fit 0805 LED diode and dedicated resistor to indicate working state of regulator

PCB size & colour
-DUAL PCB: 77mm x 37mm
-SINGLE PCB: 75mm x 26mm
-all PCBs are in black colour

What is in the offer?
TPS7A4700 single voltage output 21€

What do you get for the price
Single PCB with smt components soldered on 1pcs
SBYV27 rectifying diode 4pcs
Epcos 1uF/63V PET capacitor 1pcs
Screw PCB connector 2pcs
attached aluminum block 1pcs (works as heatsink or heatbridge)
M3 nuts 4pcs
standoffs 4pcs
Panasonic FR capacitor 1pcs

Shipping & fees, payment
Priority shipping worldwide for one PCB is 3€,for each additional PCB you'll have to add 1€. I accept only PAYPAL, fees are included in the price. You'll receive invoice for what you are buying.

Price calculation examples:
1PCS single PCB + shipping = 24€
2PCS single PCB + shipping = 46€
3PCS single PCB + shipping = 68€
...etc
Best Regards,
Ales

UPDATE: 27.2.2015 Added more components to the offer,updated price and shipping.

Dear TAD enthusiasts,
sorry in advance for the long and highly specialized post. I am in the process of building the TAD 2402 clones and I am putting together info on the xover. A couple of points that are confusing to me when looking at the french melaudia site, the hand drawn schematic by jeanphilippe and the posts by Marco Gea. I want to make sure I get the details right and I would appreciate any help.
I am afraid to post schematics here but these are readily available on the aforementioned site under the 'Filtres TAD/Kinoshita pour TSM et TSM like' thread. Of course I could post my questions there as well but I am trying to keep all my eggs in the diyaudio basket. 🙂

1) Marco Gea revises the schematic saying that L1 = 2.7mH but the hand drawn by jeanphilippe says L1 = 3.4mH.
What do you guys think?

2)I have seen people mention different kinds of HF attenuators. There are even two different schematics, one printed and the other by jeanphilippe one showing a 2 pin connection the hand drawn showing a 3 pin connection. I see mention of constant impedance attenuators and I was recommended the fostex attenuator. That's a transformer based one with primary and secondary so 4 pins. That seems different from the printed schematic that has only 1input and 1output. The transformer R100T2 based should be connected as shown here:

https://www.fostex.jp/wp/wp-content/uploads/FOSTEX_R80B_R82B_R100T2_OM_OL_A4.pdf

Does it mean that the following RLC section should be connected on the secondary downstream of the attenuator?

To keep it all in the Matsumoto family, I bought a pair of Pioneer AT 8S attenuators hopefully they are fine for the application.
Kind Regards,

Pa mentioned a new and improved F5 in the works. Any rumors, news, hints?

Winter is fast approaching here in the Great White North and I need a new basement heater.

Regards,
Dan

Hi,
I want to buy boards from china for cheap, to not spend at least $50 on interface for dynamic microphone which is XM8500.
I know I need to buy AMP and ADC, but IDK what output power should the AMP have.
Here's few things I've found (I was looking for headphone and microphone AMPs, so they don't have a lot of power, but IDK how much is required for ADC, I thought is should be something around this)
AMP:

LM386 2x NE5532 NE5532 or AD828 MAX4410​

ADC:

PCM1808 ADS1015 or ADS1115 ADS1115​

Can any of those be reasonably paired?​

Thank you for answers in advance.

​

Quick question regarding low voltage signal relays, do they degrade just sitting around new and unused? I have several NEC MR62 24V which in my case are the exact replacement model (nice for aesthetic reasons) there is a stamp on them 47/7 that makes me think 47th week of 2007 (or maybe 1997 or 1987) if that's what the numbers mean then they're at least 15ys/o.

It’s for an Onix OA21 hifi amplifier, input channel switching not speaker protection, I’ve read it’s a good idea to replace relays after about 20 years as the contacts weaken and corrode, the builder actually posted on DIYA that they should be replaced when doing a full service. Specs state contacts are gold over silver alloy and it's potted and sealed so I don't really see how they would corrode just sitting around even after many years, on the other hand the springs and coils inside might just be seized up or corroded. It's a very hard PCB to pull out IOW this is something I only want to do once while I'm recapping it.

A new set of equivalent Omrons would cost me $10 so not a big deal but I really hate to not use stuff I have on hand plus aesthetically it would look right, the NEC's are pink 🙂

A decade ago I rescued a couple of Garrard 301s heading towards a skip. I didn't think the SME 3009 arms on them competed with my Ekos 2, and the decks sat fallow for many years. When lockdown came I decided to solve this problem.

It was my intention to try to make an arm better than my Ekos 2, and I targeted the bearing as the weakest part of that arm's design (as I suspect it may be in all gimble/ball-bearing arms), and also the most difficult to diy, so I designed an arm with a very low tech but nearly ideal new kind of bearing.

Prototype 1 sounded so much better than my Ekos that I spent many months refining the design and I applied for a patent on the novel bearing.

It has been a steady learning curve going from this...



...to this...


...and this:


Serial number 2 is now in use by an audio blogger in Canada, and this is what he has said about it:

Of the former, similarly excellent results. On my first pressing of Pentangle’s debut — a disc I have listened to a million times — I have NEVER heard Jacqui's vocals sound so clean and present. A truly moving, spine-tingling experience.

Click to expand...

Dave Holland’s Conference of Birds is brilliant, wide, clear, with superb textures on bowed instruments, an absolute audio thrill. Low’s C’mon sounds bigger and more dramatic than ever.

Click to expand...

I’ve noticed that my system is also sounding better at all volume levels — I don’t feel like I need to get it as loud to get into the “thrill zone.” But this is probably just another way of saying “it sounds better".

Click to expand...

Even with much experimentation to come, I can say with total confidence that my system has clearly never sounded better. This is a stunning arm!

Click to expand...

His deck is a Sondek and he normally uses a Tiger Paw Javelin.

Please ask if you have any questions about this project.

Web site: supatrac

As in the title, I'm trying to figure out how to properly determine the maximum voltage / watts, or whatever that my various drivers can handle, and then understand how I would use THOSE numbers to set my limiters. (For both subs & tops.)

I of course want the option of maximum safe volume, without burning up coils.

At a minimum I'd like to understand the basic steps typically taken for this. I'm pretty sure it has to do with voltage, yes? But that's where my knowledge ends.

I do own a signal generator, a dB meter, a volt meter (Fluke 87) and some RTA software that can also somehow function as an oscilloscope, though I have no idea yet how that part actually works.
================================================


More specific helps would be even better, of course, so FWIW:

My processor is an EAW UX3600, and both tops and subs are driven by Lab Gruppen C48:4 4 channel amps.

The amps have a few different settings for maximum voltage, but no fine-tuning. The highest three choices are 100v, 118v, and 141v. With a typical input gain, this equates to about 630w, 880w, and 1200w per channel. I believe that's at 4 ohms, (the manual doesn't specifiy) as that's the maximum 1/8 power at 4 ohms. Everything I'm running now is 8 ohms per channel, so MY GUESS is that these voltages equate to about 525w, 760w, and 1,000 at 8 ohms.
These amps also have protection circuits that hard-limit the output to those voltage settings.

The processor has brick-limiters for each output. The parameter of concern here is the threshold setting, which is in dBu, and defaults to 6 dBu.
---------------------------------

Again, if anyone has the time to respond with specifics, then here are my driver specs:

TOPS: EAW KF394, currently running in full-range mode (not bi-amped) and each rated at 1100w / 8 ohms.
I'm not using that amp's outputs 3 & 4 yet, but will later when I experiment with the KF394's bi-amp mode

Two diffferent subs types, depending on the venue:

A: Bag End sealed 18's. I run four of them, and use one amp channel for each, so at 8 ohms. They are each rated at 400w / 8 ohms

B: Two custom-made dual 12" ported boxes, each with two Eminence Kappalite 12" drivers. (Many thanks to Art W for helping me fine-tune this design.)
Again, I'm currently running each driver off of a separate amp channel, so 8 ohms each. They are each rated at 450w / 8 ohms.

And additionally - I may build a third 2X12" sub, for outdoor gigs. At that point, I'll probably change the subs' internal wiring to parallel / 4 ohms per cabinet, so I don't have to carry another amp with me. So I need to know how THAT affects maximun voltage and limiter settings as well.
=====================================================



ANY info on this at all would be massively helpful, even if just the basic concepts.

Thanks in advance, guys.

Hi Thanks for reading. I've built a crossover for my tweeters and have soldered the cap in series with the tweeter, then soldered the inductor across the tweeter.
Is it okay to do this, to leave the components dangling in the air like that, or is it better to fix them down in some way. I just thought it would save me money on having to buy a circuit board and this way is a lot faster, but is performance affected in any way? What is the effect.
The speaker is open-back so the components will not be buffeted by the changing air pressures.
Many thanks

A warm greeting to all of you, I hope to enjoy myself here with you. 🙂🙂

I'm slowly warming up to the idea that I may need to put my Bliesma T25Bs in waveguides. I figure I'll go with either the round 6" or 6.5" augerpro guides. They will probably be crossed over to Purifi PTT6.5Xs. I've never done any 3D printing, but I have access to some Dremel Digilab printers at work and we are encouraged to use them for personal projects. So some novice questions:

1. What material works best for a waveguide?
2. How do I determine how much I will need?
3. What, if anything, will need to be done to it after it is printed to make it look good?
4. Approximately how long will it take to print?
5. Will I need to "check in on it" or do anything while it's printing? (I suppose, I probably will anyway)
6. What else do I need to be aware of?

I purchased a bag of polyester pillow stuffing hoping it consists of long fibers but it happened to be shredded and it forms a sort of loose granules. So it just wouldn't stay in one area. I'm going to use it anyway by putting it in a sack. I think a cheese cloth may work well. Any other ides?

Hi friends!
I'll delve into a new little adventure: A friend of mine is collecting antique B&O gear. Among them are a wonderful "Beomaster 1200" and a "Beogram 1200". Both have a white laquered plinth, requiring a do-over...
Just doing a nice repaint-job with modern materials wouldn't be much of a problem, I probably have all the required tools (and skills), as this is part of my professional activities. But I'm inclined to go as far as possible and use the original materials and techniques, if findable and available.
Does somebody know of a good source of knowledge concerning these quite specific challenges?

thank you!

For sale matched pair of tubes, Nos and new. I buy this some time ago from Langrex from UK. I thing about 80 euro to get for this pair including shipping to EU. Or best offer.

New, never used pair Mundorf SiO capacitor, matched pair 0,1uf. I buy this by Hifi collective UK, but never come to use this. Price 50 euro including shipping inside EU. Payment paypal for friends.

SOLD

This diy subwoofer made by Toids DIY Audiolooks is very impressive.
It does require room gain and dsp to go to 20hz.

Using a SB Audience Rosso 21SW800

http://www.sbaudience.com/index.php/products/subwoofers/rosso-21sw800/

One woofer costs 450 euro

https://www.toutlehautparleur.com/haut-parleur-sb-audience-rosso-21sw800-8-ohm-21-pouce.html
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I am selling two new audio supreme serie of toroidy 2x22V 60VA
One for 60 eur + shipping + paypal charge
Both for 100 eur + shipping + paypal
Both were buyed some moths ago, and never used (only for testing)

I am cleaning out my shop and here is the detailed list of parts included:

25 Used Blackgate F Series Electrolytic Caps (10 of 100uF 25V / 13 of 10uF 50V / 2 of 4.7uF 50V)

1 New Laser Assembly for California Audio Labs (Models CL-10 /Cl-15 / ICON Mk II)

4 New RFI Reducer XLR Caps (2 Male / 2 Female)

1 Used Tang Band 6" Paper Woofer Model W6-1139SI 4 ohm (Center Concave Paper Cap looks a little rough
1 - 8" Generic Polypropylene Woofer
2 Fostex / Pioneer Radial Horn Tweeter (From Audiosphere Speaker)
1 Sony 1" Sony Soft Dome Tweeter

4 Used 10000uF 63V Radial Electrolytic Caps
100+ USED Electrolytic capacitors - Various sizes and voltage ratings

8 New / Used 6 Ohm 50W Heat-Sinked Resistors with Flying Leads

1 True 75 ohm BNC to BNC coaxial Cable - 6 ft in length
2 Pairs of 18" RCA to RCA Interconnects
1 Single Female to Dual Male Splitter RCA Shielded cable

7 Used Miscellaneous Component Feet
2 Tonearm Headshells - Both Dual (?)

Take it ALL for $79 USD with Free insured Shipping to US or Canada
OR $59 without the speaker drivers

25 Used Blackgate F Series Electrolytic Caps
10 of 100uF 25V
13 of 10uF 50V
2 of 4.7uF 50V

$45 USD with Free Shipping to US and Canada

Paypal is accepted

Hello,
I'm having some trouble with a quad 66 cd player. It reads instantly and sounds very nice but when it has been on for while there's a slight crackle on the right channel. It had a lot of dry solder joints so I started there (including the smd caps on the dac) and cleaned the lens but the problem was still there. I had another TDA1451A in stock so I swapped it thinking that, as it affected only one channel, it had to be the dac. The problem is still there and I probably should have done this before but I used the coax digital output on an external dac and the problem is present as well (still just on one channel). Any thoughts as to what this might be ?
Thank you!

PS : I noticed that both channels are separated inside the SAA7220 and than mixed again to be sent to the dac and the digital output, could that chip be faulty and cause this ?

Thinking of building an active tube preamp (or buffered preamp) and would like to add a bypass switch to have the option to operate it as a passive pre as most of my sources have enough output to drive the power amp. The signal would be split after the input selector and attenuator. My question is… can I leave the preamp powered on and simply switch back and forth between the active and passive preamp? I understand tube power amps need a load or else bad things happen. Thanks!

Hey,
I’m looking for a latop that will function as a music server. It will be also be used for internet access. I currently have a late 2012 Mac mini that’s essentially a desktop. It works fine except having a separate display is very inconvenient so portability is key. I’m unsure about budget but would like to stay under $500. Used is fine. Probably stay with a Mac but would consider a pc.
Suggestions please

Hi!
I came across an EL2003CN by élantec that has gone bad. It's a monolithic unity gain input buffer in a music labs ML825 power amp. It has high offset and goes crazy when heated up even just by putting my finger on it. It has a kind of strange pinout and is rated for 100mA of output with a slew rate of 1200V/µS. Does anyone know of a suitable replacement (the full datasheet is accessible on alldatasheet) ?

Am trying to get enough information to understand the necessary parameters for a ripole sub driver. Optimum characteristics for different size drivers. Seems that Qt increase as driver size decrease and decrease as driver size increases. What about cone stiffness and driver mass? What about acceptable linear excerssion? Larger cones would not have to move as far but what are the practical excursion ranges.? Would like to be able to search for suitable drivers but from looking at published designs it seems that there are no set parameters with many different drivers being used.
It would seem to me that dual ripole systems are the best compromise and that larger drivers in the 15 to 18 inch range would be the most practicle way to overcome the largest and most common complaint of this design which is output. Ripoles are not the most efficient design but they would seem to be the most compact. For home theate systems where outputs above 105 db at low frequencies are desired it would appear that either multiple dual 12 inch ripoles are required (and this makes good sense in terms of driving the room) or a smaller number of 15 - 18 inch dual ripoles. I am wondering where the turning point is. Larger drivers 15 - 18 inch usually end up costing more and long throw versions are not as common as the mechanics become more involved with the higher mass structures which is part of the increase in cost. The 12 inch driver would seem to be the best all round compromise in terms of moving a lot of air and keeping the cost from getting out of hand. For a given size of motor the 12 inch represents the best balance that I can see in the market place from a cost/performance point of view.
I understand that people want/need to generate large outputs of bass in HT systems and want to get as much as they can from as few boxes as is possible but really high output at low frequencies usually gets very large or very inefficient when made smaller. Interfacing large single cabinet subs into a room does not seem to be the answer.
I am also interested to know from those with hands on experience how much of an issue ported pole noise is in ripole sub designs. Hope that we can have a polite and useful intercourse here as this topic has had some heated differences of opinion in the past. I would like to get past that to discussing the reasons behind those differing opinions. Regards Moray James.

I got an Eminence CB15 speaker in a bass guitar enclosure for free.

The Eminence rattles at around 45hz, which I notice is near it's specified resonant frequency. When I gently move the cone in and out by hand, with it out of the enclosure, I can't feel or hear any cone rub. I can't see any tears in the cone. The cone is glued solidly around the outer lip.

Recently I was able to fix an old Peavey Black Widow 15" by unbolting the magnet and rotating it 1/3, which cured the cone rub. Very gratifying!

But this one doesn't seem to have bolts. Are these things glued together?

Given the cost of recone kits now, I guess it is a paper weight if I can't get in it without cutting the cone? The free enclosure is useful for the Peavey anyway, but is there anything to be done with this speaker? It looks new and sounds great in higher frequencies.

It's with great sadness that we annouce the passing of one of our most well known members, AndrewT, aka Andrew Tymkewycz, who passed away on February 24, 2018. Andrew was the top poster here at diyAudio, and he will be sorely missed.

Andrew, R.I.P.

Andrew TYMKEWYCZ Obituary - Edinburgh, City of Edinburgh | Edinburgh News

We discussed using CMCs with SMPS supplies in the thread on All-DHT Amplifiers, but could we continue it in more detail?

Can we also discuss using CMCs in a linear supply? Where to put them, what values, and how they help hum suppression?

Goal would be to use the supply for something like a 6B4G, 10Y, 112A stage in filament bias. Could be using Rod Coleman regs also.

Here's a simple diagram to start with that you can analyse and pull apart and suggest modifications.

Hi all. I sell my last SJEP063 quad set. They only were used for checking and never used in a circuit.
Price is 100 eur each + shipping + paypal
On the other side, I found two forgotten 2SK183 in a drawer. I attach the curves I did for them.
Price is 50 eur each + shipping + paypal

Pair of 45 tubes from Emission Labs (solid plate version)

MAX 500 hours use, probably much less. Prefect condition and perfect working order. (No noise, etc.)

Original packaging (double-boxed) + certificate.

You pay shipping, whatever type you want, wherever, cost no more.

If you want, we can get the tubes tested and checked out by a 3rd party we both trust (we can discuss this). No problem.

Price is 140 euros or nearest offer.

Cheers
Deon

SBA is coming up with this....

8” SB20FRPC30-8 / Paper – Sbacoustics

sealed F3 is 64Hz in 30-ish litres, 38Hz in a vented 70 litres.
Very nice curve in a MLTL as well.

11mm p-to-p Xmax, 92dB sensitivity, Fs=39Hz, 50W handling power... a beast of FR driver!

I'll try to grab a pair when they come out!

These 6 transformers and 6 chokes from local manufacturers were salvaged from the power supply of a 2-chassis stereo 300B amp.

Chokes are 10H 100mA (4) and 5H 150mA (2).

The transformers are designed for 240VAC mains. The 2 marked transformers are: 390.0.390/250.0.250/6.3/5 from 240V @ 0.12A, 0.1A, 1.6A and 4A respectively

I measured the 4 unmarked transformers by putting in 10VAC and measuring the secondaries and multiplying by 24.

• The 2 medium sized transformers measured 800V (strange!), 36V (not sure what that was for) and 5V (300B heaters)
• The 2 smaller transformers, one of which is labelled “Heaters”: 12V (for the tube rectifiers), 16.6V (which was regulated for the input/driver tubes) and 130V (presumably for the bias).

I really should have measured the voltages in-situ but the amp was old and the workmanship poor – I didn’t want to even turn it on! I was really after the Tamura output transformers which I've already advertised.

Probably not worth shipping so local pickup in Perth WA would be best.

You can have the lot for Aus$100.

Hello all hope I'm placing this in the correct place but I need help!!I have a Cyrus 2 and when I turn on I get a large bong noise out of both speakers!! I have changed a few small caps but nothing! Still sounds fab but obviously not good for speakers on start up as I've had my meter on speaker terminals and dc comes through but then settles to zero after about 15 seconds.

once the amplifer has made this noise you can flick the amp off and back on and no noise but this is because I guess that it already all powered up still inside ? Please help and any suggestions welcome. I have tryed swapping the main caps and still the noise drives me crazy!!! I dont want to use it till i get ir sorted i dont want to damage my speakers!! That would just send me over the edge!😱 I use a psx with this and still does the noise when i use psx!

HHHHHHHHHHHEEEEELLLLLLLPPPPPPPPPP.

I might use an Elekit TU8200R in my 4-way active speaker system to drive either the midrange driver or tweeter (or both??), with sensitivities of 91-93 dB. Given its limited frequency response for either of these drivers, power won’t be much of a problem. I currently use the Amp Camp Kit for the tweeters.

I have some questions about Elekit upgrades:

1- What advantages do the Lundahl l transformers provide over the stock Japanese ones?

2- Are there any capacitor upgrades that are worthwhile?

3- Given that this amp will not see anything low frequency, are there output tubes other than the 6L6 that would be exceptional in the midrange and higher frequencies?

Long ago, all I had were tube kit products, mostly Dynakits, and I have a need to hear that sound, again. It’s been too long without. Sorry if my questions are inane.

Thanks and Regards, Mike (michiganmike711)

What are the options for a 2 or 2.1 channel amplifiers with Bluetooth and possibly line out.

Looking to make super portable and good sounding system consisting of 2 bookshelf speakers(one will have the amp bolted onto it)

It will be like a Lego transformer. Mostly use the 2 speakers attached next to each other but sometimes would want to separate them when need true stereo.

The system needs to be battery powered. 12-19v I would guess

I might add a downfiring subwoofer in a form of a base for the two speakers.

Ideally I would like 2.1 amp that can power small bookshelves + 6.5 or 8" subwoofer. If its not possible have a 2 channel system with a subwoofer out .

I've seen some options on parts-express 50+50+100w amps.
Are there any other options to consider outside parts express.

Plus need a battery. Could I use Ryobi 18v 6ah battery that comes with their tools?

I've decided to build Steve Dove's 5 band EQ that was published in Studio Sound back in 1981 (Part Nine, Equalizers 3). But, I cant find a source for the potentiometers, dual, antilog, 10K, 22K, 47K and 220K. Schematic attached.

The usual suspects, like Digikey and Mouser, don't have. Any suggestions?

Thanks in advance,
Mike

Looking for a pair of 15" @ 8 ohm Fane 15-300TC speakers.

Am located in Nebraska but asking for a friend in Oregon.

Thanks,
K

I have a pair of Audio Physic Caldera(30 years old speakers) that were passed down to me. A few years ago I tried to go active and gutted the bass crossover. Long story short, I want to put the oem bass crossover back because to me the original passive system sounded better with my 845 tube amp. It has been 5 years now, and I dont remember how the crossover were connected to the input(amplifier) terminals. The two pairs of black and red wires go to the woofers, but where is the inputs? Could you please take a look at the photos and help me? Thank you so much.

btw. This is a 3 way system. midrange and high have their own enclosure and crossover. Photos below are the bass/woofer crossover. Thx

I read somewhere about a design using the 15PR400 in a transmission line enclosure? Right now I am just looking at a BR in a 150L enclosure tuned to about 40hz. But a TL may be interesting. Did GM have a design for one floating around?

Thanks!!!

About 13 years ago, my kid had a rave party and sent square-wave like audio through my 2325. One of the right output transistors shorted and sent 60 VDC through my right JBL and blew out the woofer coil. The protection circuit - well.... didn't. The unit absolutely needs a full recap, but that is phase 2. Right now I am just trying to get the right amp module working. 13 years ago, I had ordered a bunch (a dozen each) of the output xstrs and the 747's HFE's were within a reasonable range and grouped closely. The1116A's were in two groups >1000 and <150. The also had a smaller "dome" (Cheap Chinese knockoffs?). I shelved the unit.. Now - I have replaced the TO3 2SA747A's (PNP) and 2SC1116A's (NPN) with matched pairs of these questionable (Chinese?) devices. I have replaced the three lytics and checked every smaller onboard semiconductor out of circuit. Also the power resistors are OK. I have powered the board with my current-limited bench supply that does + and - 35 VDC. Lower than the required 60 VDC but probably OK for testing. The speaker output shows 5 V DC offset which is far beyond the adjustment range, also. The voltage indication for the idle current is very high. Could these crappy output xstrs be the culprit? They test OK... Any thoughts?
Thanks, Russ KD4JO

Altec 802g original pair

Hi everyone,

All of my DIY journey was helped, if not totally so, by the great people on DIYAudio.com.

Without DIYAudio, I would not have progressed and enjoyed this hobby as much as possible. Thank you!

I would like to share a new blog that I have created which focuses on my new monoblocks and related topics. Your feedback is welcome and I will also post many of the monoblock photos on the Gallery forum within DIYAudio.com.

https://ironandglass.squarespace.com/

Hope you enjoy.

Pat

Hello - I'm a bit baffled by a no-load test on swapping the input/output on a small power transformer: 'Been doing electronics for years, but never had occasion to feed the secondary, versus primary, to get (modest plate current) HV B+ from surplus former transistor amp xformers...

In slowing ramping up the input voltage to this ~2Ampere 24vac xformer (e.g. 5:1 ratio), I was not able to get even 20vac into it - e.g. 100vac out - before it began overheating; again...no-load?!?

I regularly see 120->12->120 small ampt PS's ...but, are there some (unusual?) windings on standard power transformers that would preclude pushing them backwards - e.g. heating up on their own eddy currents? Thanks in advance for any practical experience and findings...!

I've just picked up a freebie locally.
This one needs a new power cable to be legal and probably why it was free.
But it is fitted with a new OM-10 cartridge so it's probably worth fixing up. What is it that I should do; if anything?
Lubrication? If so how and with what?
Was it considered a decent TT or just something entry level, as it is pretty basic and lightweight

How hot is too hot to subject an output transformer to? I read that the pouring epoxy hits 200 degrees, is that too hot?

I was thinking it might be interesting to make a form and end up with a nice smooth black covering on a toroidal.

Since my outputs never get warm it generating heat in use shouldn't be a problem but the heat from the chemical reaction of the epoxy could be.

I got one of these early 1970's Krohn Hite 3202 dual Hi/Low filters - online.
The switches were stuck, but some good DuPont silicone lube freed them up. Also, I cleaned the switch contacts and sparingly applied some DeOxit, plus I installed all new electrolytic caps.
This filter now works, but I want to have a go at Calibrating it.
I have a R&S RTB2004 modern scope, and a Tek 2246 scope, and Fluke 189 handheld RMS meter.
DC offset adjust is good, at less than 0.8 milli vdc.

But the other instructions have me confused.
STEP #1 ....looks like 600hz @1v is sent to the filter input and the scope input, and the output also to the scope, in X/Y mode..... and look for an "ellipse".
All I get is what I expected.... an "in phase" 45deg straight line, and that does not change with turns of the dial.
I'm also not sure what they mean by "20 divisions" ?



Also, with only 1.0 volt input, how does the VTVM read 20 dB ? Is the VTVM on a different scale setting ? Because with my DVM on dB mode, 1v is 0.1 dB....and.... 20dB is about 10vac.

Here is a meter scale from an older VTVM.......
(thumbnail)

I'm looking to purchase one or the other. If something terrible should happen are power transistors etc available?

Bob Cordell Interview:

Here & presentation here.

I am selling for the benefit of a former stereo salesman who has fallen on hard times (and who has trouble paying for food and fuel) an early version of the NAGRA "SN" battery-powered tape recorder, priced below market. The auction is on eBay: https://www.ebay.com/itm/334668550624

There is a YouTube of the item running: Login to view embedded media
I am hoping that by not asking cray-cray money (like everybody else does when a NAGRA SN shows up), I can help him have a nice Christmas.

john

PS: SOLD at $1,219.

Looking to sell my collection of vintage NOS chips for audio applications. Some rare and discontinued stuff with it. I haven't counted them but you get the idea.

Not interested in selling single ICs - only the lot!

70€ incl. shipping in Europe

Hi !

I have some difficulty to evaluate output tube dissipation power. KT88, 455V B+, 85mA idle current, ~38.7 power.
In LTSpice model I(anode) shows peak 330mA. How max anode dissipated power not exceeding 42W?
What am I missing in this particular case?

Thanks in advance.

Hi, the woofer in question is: Audio technology 18h52 17 06 SD

I have understood that QTS value 0,32 should go more as vented, but just curious could it actually work as sealed?

Im not worried that vented box will not work, since my volume/port length for woofer will be same as Jeff Bagby´s Spirit Winds.
Just curious since i know i will be using high quality subwoofer anyway, could i stuff it and try to see do i like actually sealed bass better.

Looking for a pair of sb26cdc tweeters, thanks

Hello! My name is Mike Ruiz Serra, I am a furniture designer based in NYC. Over the past few years I've been mastering the craft of plaster based composites for custom furnishings. I've developed an appreciation for vintage Elipson loudspeakers, as they were using similar materials and production processes.

Last year I built this set of speakers (images below) as a sort of homage to the Elipson AS 30's. I wanted to capture the aesthetic qualities and feel of the vintage Elipson's while using more modern components. For these I used Seas Prestige FA22RCZ full range drivers and designed the cabinets and ports based on the recommendations from Madisound. I use these everyday and they sound great, but I'm interested in producing more of these speakers for select clients and friends. But because I'm not formally trained in speaker design, I'm looking for some guidance.

I really love the Seas drivers, but I'm thinking about switching to Supravox speakers. Specifically the 215 Bi-Cone Signature model. I'm thinking about switching to Supravox because I heard these were the speakers that Elipson used to use, so maybe they're better optimized for this unconventional cabinet design? Sadly I'm unable to get a hold of anyone from Supravox and I was wondering if anyone has any experience with these speakers. I'm mainly trying to figure out: What is the recommended cabinet volume and port size/depth? Is dampening necessary on the inside? I'm also trying to figure out the ideal wall thickness for my material, not sure if this matters.

I'm also considering just sticking with the Seas drivers, as there seems to be more support for these.

Looking forward to hearing your thoughts on this, thanks!

Hello, I have an Alpine 3566 that was purchased from a Japan site. The seller claimed the amp was working, however there was no audio output.
I completely replaced all electrolytic caps in the amp. The amp now powers up but goes into protection mode for about four minutes, then the protection led goes green and the amp provides audio. The four 2SC4024 transistors in the "cancel" circuit of the inverter get quite warm after a few minutes , I then pull power away to eliminate any further damage. I probed the uPC4094C chip . Pin 5 has a sawtooth pattern, both pins 9 and 10 have the square wave but the wave looks distorted to me. pins 13 and 14 have 5 volts. I have since taken out the rectifiers to disconnect the power supply from the output section. The protection led immediately goes green and the power section stays on. The four 2SC4024 transistors only get warm now but the square wave still concerns me. Any ideas on what to check? Thank you.

Hello everzbody, i looking for speaker protection (dc protection) but without power supply that i can mount directly on speaker , i saw couple of these devices but i cannot find schematic

Hi all,

I completed my latest project, a high value inexpensive build based on the Dayton MX15-22 drivers that were on sale a while back for a pretty deep discount from PartsExpress. Pretty decent driver for the cost when on sale. These towers are 50 inches tall by 20 inches by 20 inches. The slot port is at the top and exits behind it with a 3" x 18.75" opening and a total length of 34.6 inches. I modeled them in larger cabinets in WinISD and then built a physical model with scrap to verify my calculations for my port and my final cabinets show the 20hz tuning pretty precisely so I'm happy with how it all worked out. The front is double baffled and I used 1.5x2.5 stud for bracing. Each driver is powered by a single Behringer NX3000 that I got on deep sale (50% off) in bridged mode and they're handled by a miniDSP 2x4 HD. The cabinets are made with 3/4th inch ply that already had Birch veneer on them that I found at Lowes for an ok price and I stained them with Early American minwax and sealed with a satin poly.

50" x 20" x 20" Cabinets
Bass Reflex, 20hz Port Tuning Frequency
Net Internal Volume 8.2 cubic feet
Dayton MX15-22 Drivers (wired in series; 4ohm)
Behringer NX3000 Amplifier (Bridged; each)
MiniDSP HD 2x4



Cabinet 1 DATS V3 Impedance Sweep to verify port tuning frequency:



Cabinet 2 DATS V3 Impedance Sweep to verify port tuning frequency:



Near field measurement of the driver and the port to show the relationship and also examine the port's output which has a nice gentle peak SPL output at the 19~20hz area.



Here's the two towers referenced at 95db individually and then with time/phase alignment in the miniDSP to get a summation result in in the dark blue line. The final net summation gain is about +5db from 17hz to about 60hz. No smoothing applied.



And finally, I use the summation results to then apply a heavy house curve EQ that has an overall 15db slope down to 19hz; again no smoothing applied. The room is 18 feet x 14 feet x 8 feet. Currently I have -6db in the miniDSP on the output as I have lots of headroom still from the summation gain and was peaking 115db while watching a few heavy scenes with my AVR at -12 and -10 to get an idea of things while auditioning and running REW RTA to see the peaks. So the amp limiter lights never blink and I'm comfortable with the 110db peaks. More than that and It starts to be too loud for comfort. At max output, everything rattles and shakes, and I'm not about that kind of noise. Overall they effortlessly do their job with lots of room to spare.



Very best,

I have no ideea how much I should ask on it, but looks pretty rare.Do you have an ideea for a good price?It has stereo mike for recording and the speed pitch control has a huge range.

Hi,

By and large I think most speakers would place the mids below ear level with the tweeter at ear level. However if you think about it, most of the time the source of sound will be above you. In a jazz bar, you are sitting down and the singer is on stage and the PA speakers are on stands. In an orchestra the you are sitting below and the musicians are on top of a stage. So in most cases the sound source is above ear height. To achieve most accurate imaging. I believe speakers should be slightly above you

What are your thoughts and arguments for or against this?

Here is a schematic of jbl charge 3 i just want to ask why 1k resistor divider is used in audio output from main chip and it goes to amplifier input , and what if i use 1k alone in series instead of divider ? I m making a Bluetooth speaker and I just want to reduce disortion at full volume..please help..

Looking to build a listening room in my basement with different combinations of pre-amps, amplifiers and speakers. It be strictly a 2 channel system with variations of tube and solid state equipment as well as a variety of speakers.

Does anyone have a suggestion or recommendation on a switching controller that could handle input and output selctions, sort of like what they have in profesional listening rooms? Something where I can select different combinations? For example, select pre-amp A, run through amplifer C, and then output to speaker set B.

I'm sure I can call a few local places in ATL, but thought I'd check here first. Google isn't coming up with squat.

Thanks!

Hello,

I have inherited a pair of speakers: seas thor kit in Planet 10 quarterwave transmission line cabinets which are 49.5 x 9 x 13 inches. These belonged to two great men in my audio club and now I have inherited them. I believe they have the original crossover or something else that does not work. The speakers produce phenomenal (overpowering) deep bass and and a very forward midrange and treble that is highly detailed and fatiguing. I am looking for a crossover schematic that will suit this speaker without throwing out all the great bass and detail. I am happy to splurge on high quality components for the crossover as the drivers are excellent.
My friend that had these speakers said that this forum has had several different clever people work on this before and I am hoping that I can refine these beauties with help from the DIY community.

Regards

Rhett

This is a pair of Tomcat Audio Mono Blocks.
They are rated at 60 watts,the power tubes are Tung Sol KT120 you can also use KT88 or EL34.
The phase splitter uses 12au7 the Driver tube can use 12at7 or 12au7
They use very nice Hammond Transformers.
Front illuminated Bias Meter with adjustable bias for each power tube.
They are less than 6 months old with little play time on them.
Great sounding mono blocks with plenty of power to spare.
Local pickup only Huntersville,NC. $1350

Hello all
I purchased a Pioneer PD-S505 CD player as a non runner.
The symptoms are:
Turntable starts slowly and runs continuosly with no way of being able to stop it other than disconnecting the mains plug.
The carriage motor moves the mechanism to the outside of the disc, and if not shut off, will repeatedly bottom against the end stop.
The laser tries to focus, however there is no evidence of any beam. The lens is affixed to the laser assy (hasn't fallen out).
If put in Test Mode, the REW and FF buttons on the front panel move the carriage in the opposite directions, ie REW sees the carriage moving towards the outside of the disc.
The disc spins up without any button prompts. No other buttons are effective in Test Mode.
Voltages at test points look OK.
The tray switch and the INSD (inside switch) are both functioning.
Both carriage and spindle motors ar OK.
Any thoughts on this?
Cheers

Ok, going way out on a limb here perhaps but, is there a valve in existence, a large transmitting tube perhaps, that is capable of producing 15-20W in a single ended design, with no driver? I imagine it being some super high voltage monster, is there a valve that could do it or is it a pipe dream?

anyone have any service info or schematics for a VK-500 power amp?

So when calculating boxes for a speaker with multiple drivers you get a curve for each driver

One driver will produce -18db of 70hz
The second driver will produce -6db of 70hz

Just looking at curves for each driver

Does this mean the the final product, the speaker will have a curve which sums the bass output of both drivers and will look flatter than each individual curve?

Attached is an example of mark audio alpair 5 gen 3 + peerless 5.25 woofer. Alpair will have its own sealed box which will be encapsulated into a bigger box containing peerless woofer

Red curve is mark audio alpair 5 gen 3 in .5 liter box.

Blue curve is peerless sds-135F25CP02-04 in a closed 3L box.

Green curve is peerless sds-135F25CP02-04 in a vented 3L box.

If I decide to make a complete closed box system will the final speaker bass performance be the sum of red + blue curves?

How to calculate how much bass will be contributed by alpair 5 to final result. Doesn't it ad like 3db to final result. Is it just adding the DB values st a certain frequency?

Reason I decided to keep alpair 5 in closed box is so it could handle more power and not bottom out. I like to have good amount of headroom.

As mentioned on my earlier thread here are some more Salas L adapter circuits placed on a raspberry pi board outline for music servers that run Moode Audio. I have made some new ones with a changed component footprint positioning to better suit the other boards in my stack, So the old ones are for sale if anyone is interested. I will list them as I swap out my old ones.
The 3 shown here power the Pi through the IO header. White connectors supply 5VDC. The usb is across the output and supplies 5v. It is basically Mr Salas fine circuit with a few add ons. My Pi running Moode only drew about 500mA. If you were drawing more you might need a bigger heatsink. My heatsinks didnt get hot. It was supplied by 9v dc by an old linear wall pack. There is a provision on the board to fit diodes if you wanted to power it by a suitable AC voltage but I only fed it from 9 VDC.
$45 AUD each. I will throw in a volume pcb front panel if you want one. I have made PCB front panels for a few of my projects and the end result can look quite good. I fitted a rotary encoder on these and connected it to 3 pins of IO and used it for volume control in Moode. It worked well.
prefer Australian or NZ postage.

I am looking for at least 1 of these drivers, however I am willing to buy pairs.

Here is some info: http://telefunken.te.funpic.de/philips61/philips120.jpg

Please let me know if you can help. Thanks!!

Hi All.

Working on a Lab Craft Type 605 Scandinavian Turntable and noticed the fine screw which holds the Cartridge to the Head is not long enough.
I suspect partial thread stripping in initial part of the cartridge plate.

The Cartridge includes the Markings "2R2 Japan"

The fine screw has under cap thread length of 5mm.
I'd say it needs 7mm-8mm.

What thread size would this be.
Are such screws common or readily available?

I have an old poweramp Denon POA2400 that i want to recap and give a little Tlc. The main capacitors in the powersupply are Nippon Chemicon 10000uf 80v
seriesDL which are probably obsolete now, but when i search for it online, it feels more like they dont exist at all. Do anyone here know anything about that specific series?🙂

How do you deal with the lack of feedback to your designs and general validation as a designer? I'm depressed to be honest...

FS: Nelson Pass A40 PCBs

UPDATE: a new batch of PCBs arrived! See post #17 below for photos of a bare PCB, post #28 for the schematic, post #33 for photos of a sample build.

The price is $10 per pair of boards plus shipping. Estimated USPS shipping prices are $5 for the continental U.S., $12 for Canada, $16 for Europe and Australia, and probably for most of the other countries. PM me if interested.

For details on the amplifier see the relevant article on FIRSTWATT web site and another one for substituting modern parts. The PCBs are double sided and follow the original 1978 design. Each 3"x3" PCB is for one channel front end only (power stage is off board), so you'd need a pair for stereo.

Hi,

I run across interesting and simple solution of dynamic BIAS circuit designed by P.Turner. Looks like it have pros of both of fixed and cathode BIAS. However, I have some doubts that it works as intended. There are 2 versions of the schematic dated 2003 and 2014, I have attached both, and will refer in latest version in my text.

Web mirror of article, original site doesn't exists anymore.
https://www.vacuum-tube.eu/www.turneraudio.com.au/300w-5-bias-stabilizer.html

At first sight, it even protects tube against over-current and overheating, yet voltage on cathode resistors R12/R13 820 Ohm will decrease when transistors Q1/Q2 start to conduct, leaving protection circuit off. Transistors in dynamic BIAS are in series with resistors only 33 Ohm. Although hard clipping with low-frequency signal and consecutive output tube over-current is an unlikely scenario, circuit need to be more foolproof. I think R20/R21 which are in series with BJTs must be increased to 300 - 400 Ohm.

Please share your opinion and ideas. Thanks in advance.

Hello all!! I currently in the process of treating my own mixing and mastering room in my house. I’m building corner bass traps. My dilemma is I see “everywhere” that everyone covers their panels and traps with cloth. But I was going to cover mine with acoustic 1-1/2” or 2-1/2” foam. It would be easier and look nicer, and I’ll get the extra thickness for more sound absorption. “So I think” but I may be blocking the audio, thus not letting the traps do their job. Please help. And thank you. Cloth or foam. Thanks again. I’ll post pics.

I just got this cheap [ $50-] turntable for the shed and plugging it into my little party mixer I have the worst earth hum.
There is no wire connector with this TT for earth connection to the amp or pre-amp/mixer and the instructions on-line are no help.
Is there a workaround or does simply using the inbuilt preamp and treating it as a line level input work best?
I haven't yet tried using line inpiut as it means taking everything apart and it's almost time for me to start cooking dinner

Looking for a variable power supply for a pair of Oleg Rullit lab 8 field coils.Needs 0-120 vdc.Any ideas or circuits would be great.

Hi,
I need to build a system able to connect and remotely switch my 2 amplifiers (Both transistor based) with the same loudspeaker set (Right, Left and Sub out). I've already read many posts about loudspeaker switching (Considering both mechanical and DIY Solid state relay), but I need some suggestions.

The Switch control unit would be arduino (ESP8266) based, and both my amplifiers can be remotely controlled (RS232 and IR), so what i was thinking to prevent any sort of problems (like arcing) is:

• Remotely Switch off both the amplifiers outputs
• Select the "Active" amplifier via relay
• Switch on the Active amplifier

And talking about the relay: I was thinking about using a serie of DPDT, Latching relay consisting of:

• One Power Relay used for ground connection for both the loudspeakers
• One Power Relay for each loudspeaker positive
• One Signal Relay for Subwoofer ground connection
• One Signal Relay for Subwoofer positive pole

Should this be a good idea to build a safe Loudspeaker switch? Have you got any suggestions about the relay specs to find?
Why was a Latching relay never considered? It should be better as there is no signal needed to keep the NO state closed or is there something I've not considered specifically for loudspeaker DC output?

Thanks!