I have accumulated a number of drivers over ti



me. Is it okay to throw them all into the same box or will they end up demagnetized or be otherwise affected?

Hello Gents,

Appears to be difficult to source the reservoir caps for the 665-VXi. Pin distance has to be 22 mm (of which there are few...most of them are 10 mm). I found cornell dubilier 8200uF 80V with this pin distance but the diameter of 40 mm is just a tad TOO big. I could drill an extra hole on the PCB and go for a 10 mm pin distance one. Any suggestions on the brand or just use a quality brand like nichicon, Panasonic or Elna etc....?

w.

Hi, please I'm completely confused with REW (5.20.13) basic A*B operation result. I'm trying to multiply my response (nierfiled + port) with bafflestep response (generated by Diffraction & Boundary Simulator 1.30 aka DBS). All each freq. responses seem to be ok, as well as DBS .FRD output - see attached pic. But when I make A*B - (NF+port) * BF.frd the result is strange. It's not possible to have more then -6dB difference in final response, but there is more, about -8dB@100Hz. What's wrong here ? It seems, there is an 3dB offset - very suspicious number, isn't it ? 😉
Thanks a lot.
Edit. For ex. here is using the same method to join responses.

Fully assembled and working well. $400+shipping from 66213 in the US. The box is 8 pounds 7 ounces, measuring 12"x12"x7".

The kit was purchased through the DIYAudio store and I upgraded a few capacitors, listed below. The original instructions and remaining stickers come with it. I didn't put all the stickers on since I didn't like how they looked and the knobs are easy to figure out.

• Tubes are Northern Electric 12AU7's.
• Muses01 opamps in phono stage.
• All four coupling caps are 0.47 uF Mundorf Supreme
• Phono stage also has two 10 uF Mundorf Mcap EVO SilverGoldOil caps

No known issues. Here are my nit picky comments:

• No power cord supplied since mine are all boring computer cords. You probably have better.
• The top covers has a very small nick in the paint, seen in the photo.
• While cleaning the PCB, I made a small scratch in the top layer in the phono area between the opamps. I covered the area with a small piece of polyimide/Kapton tape to protect it.

Let me know if you have questions.

I’m selling my Zapco HDSP-Z16V DSP which is originally designed for car audio. The system is very modular and I upgraded the stock DAC on the first 8 of 16 channels to the AKM 4490. This unit can also be upgraded to ESS 9038Pro for around $750 if you so desire. The unit is in good condition and 100% functional. I broke the door off of the optical port changing cables so had the optical port replaced but had to source component with a slightly larger footprint. This means there was a modification made to the input panel to accommodate the larger footprint. There are a couple of small scratches on the name badge as can be seen in photos. This is a great solution for DIY speakers and prototyping. I now use a computer sound card for my prototyping and prefer building passive speakers still🙂 This is a great sounding unit. Asking $1300 with free insured shipping in continental US.

*SOLD""
This is a I2S to simultaneous mode TDA1541 dac board designed by Miro. I have built a few boards, and i am only keeping one board for my own system. This is the second spare board i am trying to sell. It is built with care and high quality parts, tested to work with stability. Your own PSU and i2s source is required to complete this DAC for it to sing.

The 14 decoupling caps for the TDA1541 chip are high quality RIFA MKP, with values as per Miro's recommended BOM. Decoupling caps for the psu are KEMET MKP, and electrolytics are mainly Nichicon FG for the DAC section and ELNA Cerafine for the op amp IV. Resistors used are Vishay, including the zero ohm jumpers and the IV resistors is DALE RN55. Logic chips are decoupled with high quality Kemet SMD x7r capacitors.

This dac is designed by Miro and more info can be found here :
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-268#post-7159210

Miro also designed the PSU for this dac (not included in this sale):
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-268#post-7159234
Please study the power supply requirement carefully if you intend to use your own psu design.

Important things to note :
1. If you intend to have no capacitor at the output, it is advisable to have a dc protection board as explained in the post:
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-285#post-7187720
2. Tested with JLSounds i2s card, i have trimmed the TDA1541 offsets to be null and very stable. Any changes to the board, including inserting different op amp and different TDA1541 chip will require adjustments again. Please do check and do necessary adjustments by following the instructions by Miro. You will need to explore this on your own, with your i2s source connected.
3. All components, including the TDA1541A chip are new, which is only used for the testing of this DAC. The exception is the pair of output op amp AD797, which are old and used by me for previous projects.

Of course, the board has been tested and playing well. Price for the board is 220USD, including shipping worldwide registered. And as usual i will buy coffee for Miro.

Hi people, I have just pulled out a very old pair fo Tannoy Mercury m2.5 speakers.... both only have their tweeters working where i have pulled everything apart and the woofers are all connected fine... I assume this is a chip issue.... can you suggest how this can be fixed?

Hi,
I need some screws that are made to imperial size standard but do not know how to name it to look for on ebay or elswhere.

Length is with the head: 0.625" or also 0.73"
Width is 0.25 for the screw
Head is only 0.37" width and 0.125 high". Loot at the pictures.
The screw-thread is less tigth than what I found in EC...

How would you name it in USA or Great Britain please ?

The high side fets are heating up. The waves between high and low side are slightly different. The yellow trace is the high side.

From the alignments B4, QB3, C4, SBB4 and BB4 I prefer clearly the last, when I want to have a high efficiency sat box with tuning frequency between 55Hz and 110Hz together with an additional high pass filter.

In Richard H. Small's paper "Vented-Box Loudspeaker Systems" (Part I-IV) under
https://sdlabo.jp/archives/Vented_Box_Loudspeaker Systems_Part_1-4.pdf
there are only small information on page 322 concerning this to find (actually only scorned resp. derogative):

Similar effects occur with other alignments. It is not difficult to see why the vented enclosure is sometimes scorned as a "boom box" when it is realized that the values of QT required are much Iower than the majority of woofers provide [15, Table 13] and that a historical emphasis on unity tuning ratio regardless of compliance ratio often results in erroneously high tuning.

Otherwise I will not find anything about the BB4 alignment.

OTOH such an alignment is obtained when the surface area of vented port corresponds to that of the diaphragm area from the bass transducer resp. driver, as long the volume of cabinet is below approximately 100 liters - for an example check out the mid-bass unit, left side on last image in post #5 under
https://www.diyaudio.com/community/...oofer-precision-devices-pd2150-inside.197034/
Along with a high pass filter one will get very clean and tight bass in the area between 60-200Hz so as a very high efficiency character.

In the frequency area between 20Hz and 120Hz I have a lot of experience with high pass filtered BB4 alignments.
Thus the most important question is for me currently up to which maximum possible frequency area one can operate according such an alignment without having to accept any disadvantages in sound quality. This I haven't check until now.

This I want to know because I'm thinking about a vented box with BB4 character with Fostex FE83 - go to
https://www.fostexinternational.com/docs/speaker_components/pdf/FE83NV2.pdf
and a very small volume (tuning frequency maybe 200-300Hz so as highest possible efficiency.

Thanks in advance for an advice.

P.S.: under
https://www.diyaudio.com/community/threads/loudspeaker-alignment-questions.42386/
there are no information to find concerning this.

This is a last resort attempt to see if my old ARCam Alpha 6 amplifier can be (or is worth) salvaging.

The amplifier stopped working a while ago and having taken the unit in for repair the advice from the workshop is that the "power amp mosfets are short-circuited". Given the unit is from around 1993 and parts are difficult to source, is it worth persevering with or do I add it to the e-waste scrap heap.

Any advice is welcome.

DD.

Anyone recently bought any Jakeband sockets? I emailed him at jakeband@gmail.com but have not heard back. I'd like to buy some GM70 sockets.

TIA,
Jim

The aim of this project is to build a simple class A monorual amplifier to play music from a CD player to desktop or floor standing speakers. The design at first pass (pun intended) uses a single transistor and minimal components. Initial testing has found that acceptable sound quality is possible, but I need to build the complete amplifier for proper testing.


This project owes much to the thread here: https://www.diyaudio.com/forums/solid-state/178761-single-gain-stage-transistor-amplifier.html

Peter Aczel and the Audio Critic wrote a review of the Beolab 5 over seventeen years ago, and I thought I'd post it here since Aczel has passed and nobody knows whether this content will be around in the future.

It's a really interesting speaker and especially good for cloning, now that 3D printing is so ubiquitous.

I bought a pair of Krohn Hite units for $100 total.
5800 function generator
4400 Ultra Low Distortion Oscillator
Neither had their fuses, and with new fuses, lights came on but both failed produce a signal.
Easy fix for both though.... the PSU electro caps and all tantalum caps were replaced.....and both came to life.
I bought the user/cal manual for the 5800. I cal'd it and it works well.

I cannot find the cal/schematic manual for the 4400.
This seems to be an early version, with 600 Ω outputs only. PC board date is 1980.....


The opamps employed are of the same era... glorified 741's and 300 series.....
MC1741 (x3)
LF13741 (x1)
LM310 (x1)
LM318 (x4)
....all directly soldered to the board, among a mixture of carbon and film resistors, etc.
Without a schematic or a Cal guide, I don't know how to adjust all the trimmers for lowest distortion.
I did pull the 741 types, and added sockets. Also, under the board I soldered some 100nf cer. caps to each power pin, to ground.
These opamps were lacking these, whereas the LM310's already have them.


Below, is the entire board, during the cap replacement, but before the 4 opamp swaps (on the left)


You might be able to see that i swapped to newer opamps, LF13741 AD845, MC1741 OP27. These were chosen from my spare chip collection.
There was an improvement, where the 2&3rd harmonics were now several dB lower.
The only way I can test distortion is using the FFT measurement on my R&S scope.
DC is removed via trimmers on the rear panel...obvious and easy.

I did not want to swap any of the 300-series opamps until I can find a proper manual and schematic. (I've looked everywhere).
That's where I stand. Anything you want to add is appreciated.
=R=

Sometimes when loading the page I obtain an ugly looking. Do anybody know why?

Kind regards.

Hi

I have an old nad 319 amplifier, which unfortunately is completely screwed up. The protect circuit would not turn off. In the beginning, it was only the relay that messed up the signal, but when I got that fixed, the voltage wouldn't drop on the TA7317 (protection circuit). After days of soldering measuring and burning components, I have come to the conclusion that I need a new psu-pcb. The only thing keeping this pcb together is the soldering mask. There is a +/-67V and a +/-60 V on the board. The 60V, which supplies the emitter-followers appears to be very stable, but the 67V running the protect circuit and signal amplification is very unreliable. This is the bottom view of the pcb:



(I have added some resistors to discharge the capacitors, while trying to fix it).

The question is: Do you think I should try to make an exact copy of the old layout or should I just make sure the connectors are placed correctly?
Before I start my pcb program - has anyone else done this before? The pcb is the same as the one in nad 317.

Regards
Christian

Hey Guys

I have a laptop and my digital music collection playing through a dac. What programs do you guys use for this purpose? Can I control payback using your smartphone?

Hello!
I was looking at the PCC85 curves, simulated a simple common cathode triode stage using an ECC85 model, and noticed that the anode voltage for the given bias was way off chart. First I blamed the model, but looking at the ECC85 datasheet I saw the curves are different from the PCC85, and both models I used matched the ECC85 curves. Both datasheets seem the original Phillips. Is that a fact that the tubes are that different, other than the obvious heater requirements?
Below the difference in anode voltage for a -3V bias, Ia 7.5mA, 262V vs 215V. I keep looking for the stupid mistake I may be doing but can't find it.
Regards,
Jose

Thinking of making a pair of these but are confused by the plans. The driver and internal panel is shown 40mm down from top, the driver cannot be fitted that high. Also the port is 32mm long, is that including the box thickness. What value should these be, Thanks.

Hi all!
It has ben many years since my last post here, I guess some 20 years, I am now retired an have some more time to my Hobby.

I am working on this CFP, which causes me som troubles.

I would be wery thankful if any of you could give me a hint to solve my little problem.

I have attached files to give you an idea of my project.

Micro-Cap schematic:

Kicad schematic:

KiCad pcb

KiCad 3D

Pcb under test

Test setup:

Here is the problem:
1. When I power up the amp without speaker connected all is fine and dc off set at the output terminals is 70mV. After powering up I can connect the speaker and hear some music.
2. Powering up with the speaker connetcted causes the amp to draw a lot of current, and I have 6V on the terminals.
3. Powering up with a cap in series with the speaker, all is fine and I have music in the speaker.
4. Powering up with an 120 ohm resistor in series with the speaker also does the trick, with les music volume of cause.

I really would appreciate som help, please!

Henrik

Have been liking the sound coming out of these 15" bass modules (https://www.diyaudio.com/forums/multi-way/277565-legis-horny-tales-20.html#post6233392) also when used as a 2-way woofers and one idea lead to another.😀

I already have the "closely TH-4001 clone" horns from Usher D3 and the 15" top and bottom bass modules so I will only have to build separate middle modules that sit between them.

The speaker will likely be 2,5-way and passive single amp system, driven with a flea watt tube amp😉.

The ready speaker will be 230cm tall and 115cm wide and 40cm deep. Lot's of Sd and even Vd even though they are sensitive pro drivers. They only consume 0,92m2 of floor space per pair and they can be pushed completely against the wall as the terminals are at the front baffle.

The 12" drivers are already ordered and I decided to get Fane FC-123F02 (got the last stock, it's discontinued model) which are pretty much the closest 12" equivalent for the 15" FC-153F01 woofers which the others are.

They seem to have the same kind of motor which has copper faraday sleeve since the impedance is also very low 25ohm at 20khz. The motor has superbly low H3.

We'll see how they sound raw/wo xo and measure when they arrive from the foggy island.😉 Will post some measurements...



Here are couple of sims.

FC-123F02 in 80l box (qtc 0,495) and FC-153F01 in 110l box (qtc 0,55). The phase should be quite agreeable inside +/- 10deg between them.



Here's a sim imported from the Vituixcad's diffraction tool. the 2x2 12" matrix is full range 0deg and the 15" 0,5-way woofers have 15mH lowpass coil.

Just to get some idea how the matrix will lobe off-axis. Seems to behave quite good "many tens" of degrees, and the power response is quite even at least in sim. I presume they will propably work best in at least slightly treated rooms where the frontal/listening window response dominates the power response (in how you percieve the balance and what the listening spot response is), so I don't have unrealistic hopes for superbly well behaved power response. Low acoustic xo point around 700-800Hz will help.



I already have a 2-way "Colossus lv1" system playing here🙂 Works quite good even with a proto xo with only 1mh coil as a low pass for the 8ohm wired mids so almost everything comes through. The phase is something like 100deg wrong/makes a step at the xo point, so adding another pole to mids (like in Usher D2/D3 it is) should fix that. Big closed Sd is a funny thing in nearfield.😛

Couple of videos:
1: Lv.1 Colossus - Yao Si Ting - YouTube
2: Lv.1 Colossus - Unforgiven - YouTube



Here's the listening spot response of the Usher D3/TH-4001 horn (with TD-4001) with no toe in like in the picture, with the original Usher D2 xo (without the small low pass coil that is there to tame TD-4001's 20kHz peak).

Hi, new to this whole thing btw, go easy on me.
I have two beovox S25 without drivers, just the cabinets.

I was wondering if i should put a 6.5" woofer + 2" tweeter, or woofer + 2" fullrange.
And then also what the filter + crossover freq should should be.
Saw some places say 3kHz-3.5kHz is good?

Resistor ID help. Discolored from heat.
It is hard to determine the colors on these resistors. The small one in the lower left measures 10k. Next one up measures 33.1k.

Over to the right the lower discolored one measures 1.5k and the one above it measures 32.4

Here is the schematic.

The bias of ECC99 is like 21mA.
The bias of MOSFET is 2A.

The output at 1 Watt is fairly low THD. Like leass than 0.02%.
Also at 10 Watt is the THD less than 0.10%.

Welcome with critic and improvements 🙂

Hi! What is the input impedance of ACA Mini??Thanks!!

I want to make a couple AC bookshelf speakers with a single full range driver, I see there is quite a bit of info for 2 way AC builds, but I'm really keen on just a single full range driver.

in regards to FAST / WAW, I have an idea bouncing around in my head for adding a passive radiator to them or a couple smaller SA subwoofers for a 2.2 setup at my office desk.

I don't have any real ideas on what I would use for an amplifier...though there are a couple of affordable DiY kits by Decaware that have caught my eye. I also don't have any driver selected, but I expect if there is a suitable plan out there it will direct me with what I should use.

if the music these will play will help with suggestions, my tastes are quite eclectic but for the last couple of years I've had a steep leaning towards orchestral and instrumental with a preference for the strings.

I've been reluctant to play with the speaker calculators as I have dyscalculia / dyslexia and a very bad memory due to a TBI (which is why you'll find me to be quite eccentric or oddball) I survived 24 years ago.

what say have you? also, many thanks in advance for the patience and long-suffering you may find the need to exercise due to my inferred peculiarities. 😉

I am building mono block amplifiers, so i had to snap off the left and right side of the universal PSU board. In this case

• which is the V- and the ground on the left board, ?
• which is the V+ and ground on the right board ?

thanks

I really wanted to see if I can help my cartridge stylus do the impossible, that is, tracking a groove.
So I've built my own LP weight outer ring.
There are such rings to buy on the internet... but they are crazy expansive! 500Euro or more...
I have searched for some alternatives until I came up with the idea of using Epoxy and coind for extra weight. In the end I'm glad I did! This construction is maybe crazy but truly works.

The benefits of puting such weight on a record is threefold:
-Damping the tiny tiny vibration created by the stylus.
-flatting out wraped records
-adding outer mass- eventually a stable speed.

The downside:
-Could be too much for the motor system?
-need to be carefull with cartridge placement.

Cost=15€ (epoxy is not cheap)
But the result are awsome 😀

Resaults:
Better then I hoped for! a defintive step up in resolution, better details and gain in clarity. It just feels more in control and less background noise.
It wouldn't make me stop looking for a better phonostage or cartridge but it is a bigger upgrade then I hoped for.
After two days of playing with it I had a visitor for a listen... he concluded that I'm not halucinating and that there is indeed a big step up in resulotion... however he also added that ring tooked some liveliness from the recording. I have to admit, it does sound quiter with the ring on.

So, maybe great addition for your turntable or an absolute waste of time, depending on your preferances.

Maybe it will inspire you to do the same 😉

-‘Oversized’ TL that requires stuffing to tame the peaks At the Fb, 3•Fb and 5Fb (if an ODTL layout fixed the 3•Fb)

- higher Qts / small VAS (or both) driver that ‘rings’ at those QW resonator freqs itself and stuffing appears to tame the peaks In simulation.

Just playing with Basta! and like how it's one of the only tools I'm aware of that simulates box + baffle + room gain responses all together.

Is there a way to compare its response prediction with some other tools, just to sanity check?

Basically, Basta is indicating that room gain helps certain drivers reach acceptable F3s and F6s that otherwise wouldn't look so good.

Pair of TAMURA F-7002 permalloy core 3.5k 300B output transformers made by Tamura Seisakusho Ltd.

Primary: 3.5k ohm
Secondary: 4, 8, 16 ohm
Max Allowable DC Current: 100mA



Price: US$1600 plus shipping of your choice of 8.5kg plus packaging to wherever in the world you are. Payment by PayPal.

Hi,

I'm looking for old TO-3 IRF's, not IRFP's.
2 x IRF240 and 2 x IRF9240

Walter

For Celestion Ditton 66’s might there be some consensus on the best material to use for foam acoustic damping?

When I had the crossovers serviced a few years ago I think that the boxes might have have been missing some foam which I’d like to make good.

Should I buy some 014-0431: Jantzen Bitumen Standard Panel, 4mm thick - self-adhesive (quite expensive, and not what was in the original cabinets) or would 014-0420: Jantzen Wool Fabric probably do the job? Or something else? Naturally, I’ll try to keep the filling as evenly matched as possible for the two speaker boxes.

I’m hopeful that attending to the damping will produce a cleaner and perhaps more dynamic/forward sound?

Have scanned through the many ’66 threads but would appreciate some advice even if it's only to direct me to the best section of a pre-existing post.

Many thanks.

I snagged four NE123W-08 and two NE149W-08 from a local dealer who was closing out NOS.

The first pair had a label attached reading "Tymphany NE123W-08". A very long extended pole piece and copper ring nearly as long are visible through the venting holes of the VC former. The winding extends about 2 mm beyond the top plate. In typical Peerless fashion, the second layer is missing 1-2 turns at the top (this improves Bxl symmetry for cylindrical pole pieces). 2 mm top overhang for a stated x-lin of 3.1 mm seem on the low side but are probably ok given tolerances and intentional offset.

The second pair came without those labels attached. There are Vifa/Tymphany badges on the frame and a sticker reading RM Vifa 4". Coil overhang is only 1.5 mm in one and 1.0 mm in the other driver.

The pair of NE149 drivers has the same badges and stickers reading RM Vifa 5.25". Coil overhang is about 1.6 mm in the first and a hair above 1 mm in the other which is really low for a stated x-lin of 5.0 mm.

What kind of overhangs and variation have you observed in this series of drivers? Is there a change RM stands for midrange and these are actually drivers with a shorter coil?

This thread here has pictures of the NE149W, and according to the impedance plot, it must be a -08. In the third picture, I can count about 10 turns, and the picture is taken from slightly below the top plate, so it might even be 11 turns. I count three turns in the shorter of the two drivers (pic below).

https://techtalk.parts-express.com/forum/tech-talk-forum/57431-vifa-ne149w

I use a pair of Monitor Audio Monitor 3 rosewood floorstanding towers, which seem to be quite good, but possibly look better than they sound. But lately, I've been getting the urge to rebate the front of the boxes to fit the drivers flush, to give a more posh look. I have no idea whether the sound would improve or get worse, and have zero way of calculating or guessing, so I was just wondering if anyone could give a clue as to what may happen - assuming I don't screw it up of course !!

Hellas,

i was wonderung if someone can direct me towards a solution for a boosting amp, to put between a tinysine dsp board (TSA1701, with ADAU1701) and the amplifier i choosed to use, which requieres roughly 2 volts input to be driven in full.
So far i came up with this "brilliant" idea PAM8304 dual amplifier board, which would be marvelous, if it could be a workaround, because it houses two of these little PAM8304 amps. Hence the question how good is this realy in terms of audio quality or would i just out in the next bug of noice between my amp and the dsp? (of course a would have to adjust the output by regulating it through the dsp)
The problem of the tinysine and also the minidsp 2x4 is there low output voltage of around 1V, which is great for lowlevel amps but can't realy drive other amps above that. And a real workaround, for a decent price i could not realy find or got someone a good idea of how to achieve an higher output?

Would be glad for some tips!

Swany

Hi,
Do you know where I can get this book in English? Thank you

VT231 6sn7gt Raytheon's tested on a Hickok TV7.
110 / 112 date code L3
91 / 93 LE4
120$ shipped in the usa

So today i acquired a new to me headphone amp designed and built by the late Gary Dodd of Dodd Audio out of Texas. Not new, and based on what few posts i can find, there weren’t many made. And I’m not sure anyone has any documentation which why I’m here - I’m looking for first a schematic, and a owners manual would be nice too.

I opened it briefly before i purchased it. Not too complicated Gary’s reputation included using very good parts and his stuff got lots of high praise (from more than 1 poster!). Its a single ended design with output custom Dodd transformers designed qnd built for his gear. He also built and sold a line of boutique tube amps and a battery powered tube pre! in addition to these headphone amps.

Listening now and am very happy with my purchase.. lots of detail, mids are tube sweet and hearing things I’ve not before. (But this is my first dip into better headphone space, so maybe this is what i should expect.

Sadly it seems Gary has since passed and it seems like it was before he got a chance to grow what sounds like a business around some pretty nice builds. Too bad for us…

So for now, if someone has any documentation or knowledge of how to get it, that would be a big help! Thanks

Pic attached. And if anyone wants more, let me know.

Listen on…. and keep your smile.

Wanted: Two Celestion Ditton 1" metal dome protector

Thanks in advance

Hi does anyone has experience with the 4PR65A tube as a single ended amplifier?
Its supposed to generate 15w in triode. There's a amplifier on sale that has rectified with ey500 and ecc40 is input tube.
I'm not sure what to expect. Someone has built this and im going to listen to it tomorrow 🙂. Its for sale for €600.
Im not experienced in diy, so Love to hear your opinions and experiences and tips on what to check when auditioning. 🙏

It would appear that some controls for pre-amps are not meant for use in thick front panels like those supplied with some Modushop chassis. For example, the Alps volume controls only have a shaft length of 20mm, including the threaded part, which would not allow sufficient shaft to mount anything but a very thin knob on the outer side.
Is there a smarter alternative than having to resort to CNC drilling and rebating that one can do at home?
Thanks

hi all - still starting out here learning about designing and building speakers and im interested in other designs that use a single driver and enclosure with out any other electronics to affect the sound. ive build the Le Petit and im enjoying the sound very much.. i was reading about the new pearl acoustics that manage to go no-electronics.

curious to hear others who have takes on this challenge; tips or other builds to try out. thanks in advance🙏

Dear all, when opening loudness and bass one of my Ditton 33 woofers starts cracking and distorting. I checked amp and channels to see whether the problem could be up streams but no, seems to be the woofer. Question: Where could the problem be and is it repairable (i could try to turn the woofer 180 deg and see) ? If not, any good replacement woofer ? I tried to Google but did not find any info for a modern replacement. Thank you.

I have a vintage acoustic 370 amp that uses a 3900uF electrolytic cap to block transistor DC power from the speaker. I've wondered about the case that the cap fails short circuit and I'd like to protect the speakers.

Could I put a fuse in line with the amp feeding the speaker to protect from this? I know I could but more a question of practicality. It's woofers this thing's feeding. I'd just hate to see full B+ on the speakers in the event of a failure.

https://zelfbouwaudio.nl/forum/viewtopic.php?t=30807&sid=3021065e57611a9d37b82664ce674eda

Google Translate
https://translate.google.com/

There is a legend that exists among a small circle of people who lived in Sydney in the 1970s. The legend of the Magic Amplifier. The story begins ...

Most of you have heard of Allen Wright (1947-2011) whose final company, VacuumState Electronics, is still being run in Switzerland by his ex-wife. In the early days Allen gained a reputation for the most amazing AM radio design anyone had ever heard, which was important at the time since Australia hadn't yet gone FM. He once told me that if I ever saw one (only about 200 were ever built) that I should snap it up immediately. I did actually see one for sale about 12 months ago, but let it go - I have done SDR since then and nothing beats SDR. Besides, it would have the wrong whistle filter, we changed to 9 kHz spacing years ago.

Allen was obsessive about finding the best designs possible, and would spend long listening sessions with each audio product he repaired or built. But since there was very little money in audio gear he also worked in other areas to make a living. His company Haltronics made digital test instruments. He also contracted to the Snooper Company in Castlereagh Street to repair radar detectors for cars, and a second contract had us set up a company in Drummoyne to build 1000 video games from kits supplied from the USA. I was his stand-in whenever he needed to go overseas, which happened twice. I also got very good at playing video pong. 🙂

It is a little-known fact that in the early days Allen didn't design his own amplifiers. In fact the shop in Wentworth Avenue was dedicated mostly to modifications of name brands, and Allen gained a solid repuatation as someone who could repair or improve almost anything. He also had a listening room with stacked Quad panels with a (then fashionable) live-end/dead-end setup. But most of the stuff that came through, the bread-and-butter work, was instrument and PA amplifiers. Old valve stuff, with brands like Playmaster and Orange and Phase Linear.

Anyhow, I digress. His book "The Tube Preamp Cookbook" mentions a character called "The Guru" who is a shady, ethereal character living just out of the limelight. In truth Rowan McCombe was even stranger than that. He lived in a Darlinghurst terrace house which was the home of Ellis D. Fogg, well known stage lighting guy who was a family name around the inner city area. You have to remember this was the mid/late 70's, the era of weekly bands touring from overseas and there was a huge demand for his services, as there was for Allen's amplifier repair services. Another close friend of mine, ABC journalist Peter M - who I've known since he was a photographer with ANU travel in 1972 - also lived at the house in Darlinghurst with The Guru, but he was often overseas on assignment.

So there was the little clique of people I knew from different places who had all somehow managed to also know each other. In fact it got so weird that one day that I rang Allen and Peter answered. I asked why he was at Allen's place and he replied that he wasn't, but that he had also dialed Allen and we had gotten a crossed line!

So anyhow, The Guru is the focus of this tale because he had designed the Magic Amp. It was the unkillable reference source, the standard by which all proposed designs and all equipment manufactured by other companies was to be judged, and judged harshly. There was only one Magic Amplifier, and it looked like a rats' nest, but it was allegedly amazing. I never heard that prototype but I know three people who did and they concur that it was unbeatable; or at least it was until one day Allen made a modified tube amp that finally knocked it off the pedestal, as is inevitable with standards.

But before that sad day, Allen was in the process of commercializing the design, and he laid out a PCB to make several copies to ensure that they matched the original. The Cookbook goes into an interesting story about how he messed up the first one, and how The Guru had roasted his @ss about it. But the time between these prototypes being built and the tube amp mod knocking the Magic Amp off its pedestal was very short, and it never went into production.

So, there were three Magic Amps in all; the hand-wired original, the one Allen made for himself and the one that Peter M got. Of the three in existence, Rowan's original probably went to the tip when he passed away, Hanni probably still has Allen's original in Schuffhausen, and Peter M has been promising to send me his copy for years so I can reverse engineer it. The trouble is, he lives on a tiny island off the coast of New Zealand and the amp is in a box somewhere under his son's house in Sydney. Not to mention Covid19.

So, when I finally twigged that the circuit on page 8 of the Cookbook was the exact same design a couple of days ago, I became very excited indeed. In fact, I immediately simulated it in Spice and it's good enough that I will be building a replica. Because CURIOSITY, that why. This is the amp of legends, and legends have to be either killed off or made to live on in glorious perpetuity.

Watch this space.

Again some DIY parts, stashed with me for too long, looks never to have time to be realized. I guess this DD motor is well known among DIY, regarded as one of the best ever made and IMHO it really is. No quartz but unbelievable silent and smooth.

Motor here is totally original, never been opened, great shape and 100%, working flawless. Complete with power supply, 33/45 regulation, heavy alu disc and rubber mat.

Everything checked, working strong and smooth. Only needs a decent plinth for a great TT.

Looking for 150€ plus shipping, Paypal preferred, for more info please PM me.

Regards, Davorin

hello people...ive got this fatman itube mk1 13w per channel 😱 the problem is it sounds dull and distorted but when i touch my hand on the metal on the back of the phono lead and put my other hand anywhere on the metal casing it goes normal? strange but true, ive had it apart and looked for anything that could be shorting it out but it all looks good, theres no broken tracks or loose wires, any ideas? this is the first tube amp ive ever owned i got it cheap, when its on the metal at the top of the tubes has got small hole on it, any help or ideas would be greatly appreciated guys, cheers

On my phone sometimes random thread titles are extra large and it is distracting. I don't see this on my desktop or laptop.

Png format attachments that have proper light background in the thumbnail preview, when opened with forum picture viewer, have dark transparent background, which makes details impossible to see. When downloaded and opened at the client PC, pictures are displayed correct. Example, post #2 attachments:
Issue example

This section is getting a lot of off-topic posts.

A full HALF are not about "Platform" (i.e. software) and should be re-filed to an appropriate section.

Quad 306 left channel very low output
Crossover Design, Is it really this easy?
Musical Fidelity Trivista 21 schematics
Adding Power Amplifier to My Pioneer SX1010 to drive Dahlquist DQ-10’s
300B Amplifier kits
Anyone modified a HIP4080 amplifier?

Maybe there should be a better name too. (Or time to close this and the secret beta section?)

What's the proper procedure for powering up an amp for the first time? Specifically testing voltages before sending it to the tubes.
The power filter section would be my first guess,
but how do you put a load on it before you send power to the tubes?

A Few years back I built a dim bulb tester with GFCI for my first build that worked great.I'm assuming it worked btw (it probably kept me alive) after that I never checked any voltages.
(high V? who cares?shitty soldering it'll hold.)

Hi ! looking for information about drivers i found this thread
https://www.diyaudio.com/community/threads/fs-magico-7-4-ohm-4-pcs.376772/
being a giant killers hunter for dna ... one comment hit me deeply this one
https://www.diyaudio.com/community/threads/fs-magico-7-4-ohm-4-pcs.376772/post-6800525
to cut to the chase i would love to know how do you select a driver for your project
I am mostly interested in woofer from 8" to 6"
Thank you very much and kind regards gino

Guys can you help me identify this transistor # on my 125ASX2.
i have an issue of 125ASX2 no power.. upon visual check. the transistor on this part is busted.
thank you!!

Got an A88 which has been much modified. I found the previous owner had cut most of the cables in the preamp, so I stripped all of that out with the intent of using it as a straight power amplifier. However, I have run out of both expertise and time and would like an expert to give it a once over and do some basic testing. Very happy to pay for your time and ship it down to you, but I would rather get it working than scrap it. Of course, the original case is now full of holes etc where the knobs and switches once were so I am going to build a wooden case for it. If anyone wants some 88 spares, please get in touch!

I thought that posts could be edited by the poster after it has gone live? Is that functionality gone?

I se that an individual starting a new head has he capability to edit a post to show, among other things, that an item in a list of times for sale is no longer available, or a new item has been added. How do I do that?

I checked Help, and ran a search in this forum to no avail. Do I need to ask the forum administrator to make changes? If so, how would I accomplish this?

I recently parted out an old Baldwin 41P organ, and among the future amplifier parts is an OPT labeled 512-19234B. I did a ratio test at both 60 hz and 1khz, and the turns ratio is approximately 19.3 : 1. I did not think to check the speaker impedance or wiring (series or parallel) before disposing the of the unusable parts of the organ , so I have no idea what the reflected impedance would have been. Does anyone happen to know what the typical Baldwin organ speaker impedance/wiring scheme of that era would have been? My research seems to indicate that the speaker impedance may have been 16 ohms, and there were two of them powered by the 2-tube PP 6L6 amplifier section from which this transformer came. I also would like to know if a 6V6 PP power section would handle roughly 3K impedance on the primary from an 8-ohm secondary load. Thanks for any help anyone can provide!

PS, I did find this post about the same transformer (https://www.diyaudio.com/community/threads/baldwin-transformer-swap.168380/#post-2213258). It gives 6.4K to 8 as the impedance ratio which works out to a 28:1 turns ratio if my math is correct (square root of the impedance ratio 6.4k/8), but that doesn't match what I'm measuring out of my 512-19234B unit. Hmmmmm.....

Have one of these in the shop. Customer had brought to another shop prior to bringing here.
The problem I noted off the get-go was that the front panel LED doesn't light at all and the amplifier won't pass any signal and appears to be in mute.

Taking a closer look at this front end PCB, it looks like Q1, Q2, Q4 and Q5 were removed for some reason.
The PIC doesn't have any observable clock on pin 1. I don't know if the PIC is bad, or if the board doesn't work because of the missing transistors.

If anyone is familiar with this particular VTL preamp, can you tell me if these transistors are present on other serial number units?

Hello folks,
I have a Philips CD100 CD Player I purchased back in 1983 in Belgium.
I moved to Florida 37 years ago and I would like to fire it up again, but I need help with the Voltage selection.
There is no external switch selector I can use so it has to be done internally.

I've done some reasearch and I translated some instructions using Google translate.
Unfortunately it still not clear enough and my brains cannot figure this out, so maybe someone can chime in.

I'm including a couple pictures.

Thanks.

Its a recording of a set of mine using CBT like ribbon drivers (yes with shading) and a pair of my old planar bass panels.
i bought some new mics and wanted to see if this pair finally works out. put your headphones on!! and have patience i talk allot 🙂

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Hi,

In a project I'm working on I need a source follower supplied with +40 and -140V, with a cascode of two BJT as CCS set at 6 mA.
The bottom BJT will be a 2N5551, while I'm open to suggestion for the top BJT.
Requirements are:

1. Being able to dissipate up to 900mW on peaks (it will swing up to +10V), 450mW as average (it will be set around -55V at idle), so I would say we need to exclude TO92;
2. Vce of at least 200V (I'd consider at least 230V for safety due to voltage fluctuations on the 180V we have as nominal);
3. Fit a classic TO92 pcb connection (1=b 2=c 3=e) because this is how the pcb has been done;
4. A good Hfe to improve the CCS impedance.

I've checked on mouser, and I've found some options:

1. KSC2752Y : https://www.mouser.it/datasheet/2/308/1/KSC2752_D-1810664.pdf
   TO126, Vce 300V, Hfe 40-80, pinout fits, 0.61 €/each;
2. TTC011B : https://www.mouser.it/datasheet/2/408/TTC011B_datasheet_en_20160209-1649840.pdf
   TO126, Vce 200V, Hfe 100-320, pinout fits, 0.64 €/each;
3. TTC008 : https://www.mouser.it/datasheet/2/408/TTC008_datasheet_en_20140403-1916100.pdf
   New PW-Mold2, Vce 200V, Hfe 80-250, pinout fits, 0.87 €/each;
4. TTD1409B : https://www.mouser.it/datasheet/2/408/TTD1409B_datasheet_en_20150806-1915948.pdf
   TO126, Vce 400V, Hfe 600, pinout fits, 1.62 €/each.

TTD1409B seems the best choice, do you have other suggestions?
Thanks in advance,

Kind Regards
Roberto

A Gift option has appeared under messages. It appears to buy membership time for the recipient. I had not seen an announcement of this interesting feature?

I just changed the grid resistor value from 500r to 2k on a 12b4a preamp build.
I now have to advance the volume pot significantly to reach a normal listening volume.
I have never made such a large change in grid resistor on any project...
Is this to be expected?

Hello everyone,
is anyone able to view these images?

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They are diagrams published on this forum, but I cannot open them.
I thank those who can help me in advance.

Wondering if anyone in this forum can offer guidance on a minor issue with my Unison Research S6 tube integrated amplifier. This amp has six buttons to adjust the bias - one for each EL34 power tube. There is one "bias meter" per channel and each meter has three buttons associated with it - one for each EL34 tube (six in total).

The issue is that the meter does not react when pressing the top left bias adjuster button. There are no issues with the other buttons. I have tried switching the afftected tube with a different functional EL34 tube but I'm still not getting a meter response - ie - meter needle does not react.

I may be wrong but in my newbie opinion, the tube and its power output do not seem to be affected. The tube glows as usual and there is no audible difference.

Anyone have any ideas of what can be wrong? Anyone believe this is serious enough for me to stop turning on the amp until it's fixed?

Thanks in advance for any response and guidance.
Tony

I write a post on my phone, using brave browser, copy a link, select text in the post, click on the link button in the post toolbar, paste the link, and the post is 'sent' as well as the link being added to the post...

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So the setup in no particular order;

• DAC is silent, scope is on the left channel, DAC is connected to a 10KOhm line in.
• "Default" the scope
• Auto tune
• Set time division really wide to allow analysis of lower freqs (1 per division 14Mpts in my case)
• Math->FFT
• Exclusive screen
• Units dbm
• Horizontal reference and Hz per division set to show 0-22k (35k actually).
• Label peaks, show table, show frequency.

I don't see any 50Hz, unless that unlabeled peak is it? However its more likely to be FFT bin 0 aka DC.

Not shown is the rest of the spectrum, which has two very obvious spikes way up to -20dbm of ~3Mhz and exactly 24.576Mhz. No surprises where they come from.

Odd thing is, this is post "filter". Although it is a "filterless" DAC in that it require no output filter. It isn't doing a very good job of cleaning all the Mhz crap out of there. Not that I will hear it, it's just it isn't necessary to be there and might upset things down stream. Besides, routing 24.576Mhz around on audio cables won't do your EMI environment much good.

Hi guys recently my mtx 2300 starts playing very low. When i bought it i replace the 16 mosfets, it was like three years ago. Didnt replace power supply transistors nor rectifiers. Amp was playing great and one day and the next day when i turn it on, the amp starts playing very low. When new it came with ssp45n20a and i replace for the same models on the outputs. On the power supply it has 75339P. Any suggestions on where to start, no fuse blowns.

Does anyone have any info on this active crossover? I picked one up on the bay and wondering what the crossover point is (the X-1 is a 2 way).

I would open it up but I do not yet have it in my possession...was planning on sending tone thru it to try to determine the crossover point...need around 250hz for my Magnepans...

Anyone familiar with it?

When connecting a single ended source, you often see that the single ended hot line is connected to the balanced hot line (XLR pin 2), and the ground of the singe endsed source is then connected both to the cold line of the balanced input (XLR pin 3) as well as to the ground of the balanced input (XLR pin 1).
ground at the receiver end.

I believe this last connection, to receiver ground, is not required (assuming you have enough headroom), but I'm not sure.

What do ye think?

Jan

Hello together,
I am currently building the Troels Gravensen Illuminator 5 and except the 12 MU I already got all drivers. I am interested in the 4 as well as the 8 Ohm version.
I live in Germany and therefore I prefer offers from Europe as VAT is expensive. Just PM me and tell me your price.
Greetings Björn

Can anyone recommend a good solder for me. Looking at some of the usual brands it seems hard to find a dealer in the UK for leaded solder. Everything on the likes of amazonUK seems to be lead free?

Speaker Builders Dream SALE!!!

The majority of these items are new. Those which are not are in mint brand new condition.

Beyma 15P80FE/N 15" Woofer Pair:
https://www.ebay.com/itm/275641135898

B&C DCM 414 Compression Driver Pair:
https://www.ebay.com/itm/275594401096

Beyma CP755ND Compression Driver Single:
https://www.ebay.com/itm/275594358408

Beyma CP380M Compression Driver Pair:
https://www.ebay.com/itm/275594360760

Well duh, isn't that what room correction systems are SUPPOSED to do?!?! However nothing in this world is perfect. And the idea of this thread is not to focus on the lowest frequencies. (Nor to answer by saying "use active crossovers or DSP**)

• My big question really is can Audyssey/Dirac/ARC fix the drooping response of a constant directivity horn?*
• Baffle step compensation, instead of bothering about this (which is then bothered by room boundary proximities anyway) can room correction "fix" it?
• If the correction system is allegedly time-based, can it correct time misalignment between drivers?

Any other observations about limitations-or little known strengths-of such systems please post!


*I have a bucket list dream to make some high sensitivity PA-style woofer + big horn towers. I would like constant directivity, which then means the response drooping at ah isn't it -6 dB per octave IIRC?

• I did ask this question to Audyssey but the answer was equivocal and not specific.
• The amount of boost/cut needed for a big horn could add up considerably, no?

**So far the only painless way to do surround is an AVR or pre-pro. I haven't seen for instance a pre-pro box with multiple digital out. I'm aware some folks implement home theater PCs but I will never get around to such in this lifetime.

Sale:
6P14P-EV - 500 pcs. for $10,
6P14P-ER - 100 pcs. for $12,
6N23P-EV - 100 pcs. for $20,
6N13S - 100 pcs. for $7.

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I rewatched this last night and thought that some of you would appreciate it. Fantastic sit down with Ralph, Chester, Terry, Chad, and Ruth. I think that I have a bit of a mind crush on Ruth. Glenn.