FOR SALE
I have a Connoisseur BD1 deck, built from a kit, in a homemade plinth, no lid, for sale. There is a Hadcock HD228 tonearm, Sugden SAU2 tonearm and various construction and set-up instructions and protractors, nuts, bolts, washers, allen keys , etc. in the lot. There is also a AKG P7E cartridge/stylus and another unidentified cartridge, condition of both unknown.
This equipment has remained unused and stored for 30 years or more. On testing the turntable still works so the belt is still intact. No doubt it would be necessary to remount and set up the tonearm(s)

I am open to offers for this equipment, which I would prefer to sell as a lot.
I'm based in the northwest of England, Manchester area.

I do have some matched nice NOS EL34/6L6/6V6’s. Also a bunch of NOS 6SN7/6SL7’s. Two Hammond 125CSE (8W 60mA, 2.5, 5, 10K) opt’s and a PT Hammond 290ABX.
Never built an HIFI amp before (many guitar amps) but was thinking of a stereo SE amp. Any ideas on what will sound best?

I have a 1967 black panel Bassman that appears to have been modified several times over the years. Since the circuit is far from original anyway, I figure I may as well set it up the way I want. The power section, from the PI on, is currently an AA864 circuit (schematic attached), which I intend to keep. I'm converting the "bass instrument" channel to a Marshall JTM45 preamp (details not important here). So, I thought it might be nice to turn the disconnected ground switch into a NFB switch that lets me choose between the stock AA864 NFB loop, and the greater level of feedback used in the JTM45.

My worry is the size of the resistors involved in the AA864 NFB loop. The NFB resistor is 820R, and connects at a point between the PI tail resistor and a 100R resistor to ground. I measure 0.4V there (other side of the 820R from the speaker). My first thought to get the right amount of NFB to match a JTM45 would be to have the switch connect a 330R resistor in parallel across the 820, getting ~220 ohms. (If you know how transformer taps affect negative feedback, maybe you can check my math: JTM45 has a 5k:27k voltage divider from the 16 ohm tap, I'm aiming for a similar amount of feedback using a 100:220 divider from the 4 ohm tap.) But that's a small enough value to make me worry a little about exposing the speaker to DC from that 0.4V node.

If I'm calculating correctly, the amp in its current form should be putting about 0.5mA through the 4 ohm speaker coil. Using a dummy load with my modification, I get 0.31V at the tail junction, so I think it will be putting more like 1.4mA through the speaker. I'm thinking that will be okay, but is there anything I'm missing here? Am I thinking about this the right way?

Regards to all ,
I have many new lamps in boxes, I will post a price list.
My contact email is milosnesic606@gmail.com

These are not in the packaging, but are in very good condition.
I also have TUNG-SOL 5998
5U4G SOVTEK
6ASG7 SOVTEK

If anyone is interested, I will send pictures of the lamps.

Regards to all ,
I have many new lamps in boxes, I will post a price list.
My contact email is milosnesic606@gmail.com

These are not in the packaging, but are in very good condition.
I also have TUNG-SOL 5998
5U4G SOVTEK
6ASG7 SOVTEK

If anyone is interested, I will send pictures of the lamps.

I'm basing this on a 5e3 Fender Deluxe schematic, but making some significant changes. (It will not sound like a miniature Fender Deluxe).

What I've determined so far.

Hammond 269AX PT - 250V C.T. @ 115mA, 6.3V @ 2A (I want to push the voltage, I've seen lots of homebrew amps with Russian subminiatures used at lower voltages but I want to see what they can do pushing the limits.)

full bridge diode rectifier IN4007's - This is one of the changes that will make it sound less like a Fender Deluxe, but there is no subminiature rectifier tube that I'm aware of that will work and my transformer has no 5V winding. This SS rectifier will work fine.

Hammond 1750E output transformer - 8,500 C.T. primary, 8 ohm secondary for push-pull operation. (I did a lot of research and head-scratching on this one. I can't find a load resistance spec for 6p30b tube. I saw many builds with varying output transformers, most lower voltage, some SE. Eventually I found a "rule of thumb" formula that came out to around 4600 ohm per tube, so I think this 8,500 ohm primary will work okay. If I'm wrong about this, let me know.

6p30b power tubes in push-pull. Though small these tubes are rated @ 250V with 350V at cutoff, and flow 35+mA, so IMO they are about 1/2 the power of 6V6's and I intend to get all I can out of them.

6n17b in V1 and V2. At 75mu these dual triodes are about the closest thing to a 12ax7. The curves are a bit different, but follow the same general shape. Some of the capacitances are the same, so I'm hoping the Miller capacitance is also similar.

Mounting the tubes - I'm custom building an eyelet board, so I could put a row of eyelets and solder the leads directly to the board and have them stick through holes in the top of the chassis, but what I'm also considering is putting color coded shrink wrap on the leads. Then, on the ends of the leads, taking pieces of hypodermic needle stock and soldering the leads through it so they'll fit into a standard 9-pin miniature socket.

That's about all I got for now, please offer criticisms, suggestions, etc.... I will crunch the numbers and come up with values for the resistors and capacitors and my next post will have a schematic with all that.

hi friends,
I'm lookinf for YAMAHA AX-V401 service manual (or wiring diagram)
Can you help me?

From 120 million units in 2010 to 9 million units in 2021.

http://www.stevehuffphoto.com/2020/08/02/camera-sales-are-in-the-crapper/

Hi guys,
my right channel UcD has served me well for 9 years. A bit short lived but that's how it is. Then magic smoke and now it's a mono amp (was dual mono, PSU also has several burnt components).
Any used but working UcD400HG (HxR? maybe can salvage the ones I got), V3 on my PCB. Also interested by a SMPS400A400.
Or a used NCore NC500MP? Nahhh... cheap? Why not....
Time to empty your drawers for sleeping boards!

PM please, thanks,
Matthieu

Hi there,

I tried to design a negative version of the 21st century Maida regulator using a LT3090. It works, after a fashion, but whatever I try I can only generate a regulated voltage that is significantly smaller than the input. In the example here, the supply is -200V and the regulated output is -114V, so the dropout is huge. Any attempt to increase R5 or reduce R4 then causes the output to become unregulated because the LT3090 doesn't have the required voltage across it.

Is there something fundamental to the LT3090 that is causing this? Many thanks!

https://www.cbc.ca/radio/whitecoat/the-dose-noise-health-1.6889724



dave

Have at it friends:

Scan-Speak Newsletter – Scan-Speak A/S

Hi @David McBean

I’m getting to grips with using Hornresp to simulate Ripoles. I used your example of the settings for a Ripole and they make sense, with the front port being made up of 2 x the smaller volume and each rear port being the larger volume. The target being the smallest possible volume to move the resonance peak as far up the frequency range as possible (>300hz if possible)
I have attached your original screenshots from post #13372 which I used as the basis of entering the data for a Ripole.

My main issue is how to convert the settings into actual construction dimensions. Playing with PAR, as the only value that seems to alter the response by altering the front and rear volumes are the 2 PAR values. I’m not sure what point this is measuring from. I assume it’s cm? (Why is it “16” in your example?) e.g, Do I measure this from the port to the centre of the driver or is it the distance from the from the front port to the rear port (phase cancelation distance). The drawing elongates the port but I’m not sure how to interpret this.

For now my process has been the following:
1/ Set the minimum port width (1 front and 2 rear) that allows the drivers (a pair of peerless 12” 840500) to physically fit in the box. In my case this is 130mm for each port, which is too large for the response I’m targeting with regards the resonance peak.
2/ use the area of the baffle (inside) multiplied by the port width to find the port volume.
3/ Alter the PAR value to create the port volume to match the required volume.

I feel that essentially this is backwards to what the design process should be, where the software provides the optimal dimensions rather than the other way around.

Any help and clarification from anyone re PAR and the optimal process is welcomed!

Thanks, Gis

One Pair of as new unused Dayton RS225-8 8 Aluminium cone woofer.

More listing to follow

https://www.ebay.co.uk/itm/16621921...zvysmjvqyq&var=&widget_ver=artemis&media=COPY

For sale: 20 trays like the one pictured below, 25 pieces per tray, 100 euros plus shipment per tray. Do not sell piecewise. Shipment is from Germany and only tu EU (at least for the moment).

The McGee Radio thread got me recalling these folks, they were several years earlier IIRC.

Like McGee, these folks had a great catalog, not speakers but electronic surplus. They marketed a few kits too - Nixie clocks and such.

I’m trying to recreate the crossover used for the Electrovoice Patrician IV. I found a schematic of the crossover online (they’re potted) and this is it. Not shown in the crossover is a 16 ohm L-pad used on the midbass, tweeter, and super tweeter.


That “6 mH” inductor at the top that is in series with both the tweeter circuit and the 4.78 mH inductor for the midbass, someone pointed out that it made more sense for it to be a .6 mH. Which made more sense to me after doing the math, 0.6 would cross the tweeter to where it meets the super tweeter at 4250hz vs 425hz with 6 mH lol.

I drew it out to a form that helped me visually.



So I’m confused about the midbass circuit. Having a .6 mH in series with a 4.78 mH and then a 35.4 uF cap (two 17.7 uF in parallel as shown in the original schematic), wouldn’t that make the midbass play a band pass of just 280 Hz to 470 Hz, 6db slope? That’s a tiny amount of the spectrum. Am I understanding this correctly? All drivers being 16 ohm loads I’m seeing the high pass the 18” woofer at roughly 533 Hz, the midbass plays the same frequencies as the woofer at 280-470 (??? Doesn’t seem right).

Lastly, what inductors should I get. I’m thinking with a low pass of 533 hz on the woofer I can go with a large iron core. I have one here with a dcr of about 0.3 ohms. I need two 0.6 mH coils which I can go air coil. Not a lot of power will be going through these, the one in series with the tweeter go maybe 19-20 awg? The one in parallel with the super tweeter, 21-22 awg?

What about the other two 4.78 mH coils I need, the one in series with the midbass and one in parallel with the tweeter. Going with air core on those the coils will be unnecessarily huge, if I go with a thinner wire the dcr starts to rise and goes about the 5% of the Re rule (0.8 ohms in this instance). Should I go iron core on those? Or go air core, using like 20 awg and accept the higher dcr?

I have a decent collection of coils and have a good amount of magnet wire so I can wind my own air core, but have no issue just buying some iron core.


Example for the woofer circuit, I was just planning on taking this 5.9 mH iron core and taking it down to 4.78 mH. Looks to be 15-16 awg. But would love direction on what I can get away with as far as the inductors. I can’t see the need for an 18 awg 4.78 mH air core that weighs a few pounds being wired in parallel with the tweeter.


Thank you so much,
Dan

This is to follow the idea to design a discrete opamp by joint effort, without hi-jacking John Curl's Blowtorch II thread.

The origin of the discussion can be found here :
http://www.diyaudio.com/forums/anal...rch-preamplifier-part-ii-537.html#post3136059


Patrick

I bought a pair of FE207E new in 2006 when I moved into my very first apartment! I ended up building an 8 foot tall folded voigt pipe. They sounded great and I used them all through college until I moved to an apartment where they would not fit. I happily remember seeing plans for the curvy chang in the past and I am now at a point in my life where I have time/money/wood to build them. I kept the drivers in a box all these years waiting to build a set of Curvy Chang. Unfortunately I am failing at finding any plans for these boxes. Been searching the internets and this forum for a while. I swear there was a very long thread for Curvy Chang with plans, but alas I can no longer find it.

Any help would be great.

Thank you.

Matt

I recently aquired a CD473 player which has a niggling problem I am struggling to fix. After a though clean up and replacement of the axial electrolytics and the 6800uF radial I have found that there is a range of focus offset adjustment where the TOC is easily read and usually the first track will play. If the first track does play the CD will play to the end if left alone. The problem comes when pressing 'next track' or 'previous'. Over a narrower range of focus adjustment some track changing works but there is always a number where the tracking is lost and ERR is displayed and the CD stops.

The other puzzling thing is tthat the voltage across the laser power sense resistor is 105 mV when playing and 84mV when not playing. The manual says it should be 50mV +-5mV.

Any suggestions/ideas welcome... . . . . .

Does anyone have information on the Pass Labs SIT/VFETS? Schematics of Pass Labs amplifiers that use the SIT/VFET?

His SIT amplifiers are the first of a new generation of audio amplifiers using Static Induction Transistors in a single-stage, single-ended, Class A circuit without feedback or degeneration.[13] The SIT chip combines a square-law input character with a low impedance output to form the only solid-state gain device, which Pass claims, "behaves like a triode tube." There is no output transformer on the SIT amps. The point of the SIT is that it behaves like a triode but at lower voltages and higher currents, so it doesn't need a matching transformer to deliver power to 8 Ohms. Like tubes, SITs have soft overload clipping. When brief bursts of musical energy occur, SITs react with rounded waveform tops instead of sharp and hard clipping of solid-state. SITs have a curve which looks a lot like a triode vacuum tube; low at first and climbs steadily. The distortion curve is similar, a steady rise instead of a valley with high distortion at both ends.

Is it possible Mr. Pass has invested $60m to create his SIT's?

Good day guys. I need some help please.
My Marantz SR5006 av receiver went into protection mode. Opened it up, foid 2 shorted output transistors, as well as open circuit emmiter resistors. I replaced them all today, and getting a horrible distortion sound from that channel and I cannot set idling current. In the video link, it is not my amp, but it is the exact saem distortion I am getting from my amplifier front left channel. Go to 1:36 for the distortion sound

Login to view embedded media
Replaced what I marked in red, still got the distortion

hey guys, i have a toroidal transformer from a home theater which started blowing fuse all of a sudden.
i found a sticker on the top of the toroidal here is a image of it
.

it is 67W transformer
which has a input of 220v primary
and 3 secondaries which are:
15.5v-0v-15.5v which as thickness as


24v-0v
3.6.v-0v
the remaining above 2 secondary and primary has same thickness


question1: what is the amp for all the secondary?
i found out it can be calculated by W=VA
which gives
4.3225A
2.791A
18.6A for each which iam not sure that its correct!.
question2: is the thickness of the copper wire associated with the ampere?
question3: can i change the thickness of the copper wire by like .10mm or even like drastically ?
question4: is there any alternative way for solving the problem other than doing the trivial rewinding job ?
question5: if rewinding is the only way how many turns should i do and how do i calculate the number of turns ?

There are three major classes of amplifiers, class A, A/B and D. Class A does not suffer from crossover distortion, nobody cares about it in class D, we actually put a dead time. Class A/B may suffer from it if not well biased. Intresting solutions to mimic class A include ibias by Krell. Attempts to shift the crossover point of a class A/B from zero such as class XD by Self, trying to mimic single ended class A. A good bias point does eliminate the problem in class A/B leading to better THD figures.
Electronic components do produce structural noises. Class A holds a steady current throughout the amplifier which is converted to heat, providing the much needed heating in winter. Many urban dwellers have nostalgic memories of winter nights spent huddled together around a class A master piece. This steady current also keeps the output transistors and rectifier capacitors structural noise in check. The birth of MOSFETs was what class A was waiting for.
Class A/B and class D share the relationship that the output devices are switched on/off , the difference is that class A/B is switched by the audio signal while in class D we switch the output devices on/off using a higher frequency than the audio frequency, keeping the devices cooler and shifting their structural noise, a side effect is bus pumping by the half bridge, creating an unintended boost converter. A class D amplifier will give you no warmth during winter, however a few cool LEDs might just fool you.
The choice between a switch mode power supply and linear power supply dictates the structural noise that the power supply produces. If your below the age of 25 years you may hear your computers switch mode power supply sing. Everything else around us hums at 50/60 Hz including the hum you see or hear emanating from your body when you touch an oscilloscopes probe or power amplifier input.
A linear power supply is bulky, heavy and expensive, but if well designed blends in with the environmental noise. A switch mode power supply is smaller, lighter and cheaper but sings at a different frequency from the environment probably necessitating EMI treatment.
The modern generation is more accustomed to class D sound from the modern electronic devices such as BT speakers, laptops, TVs, xphones, etc. It may be difficult to pickout a well designed class D amplifier from a class A amplifier. One might even argue that a young person is already conditioned to find class D sound more 'normal'. Class A/B amplifiers are the grail of simplicity and are often coupled with a high quality switch mode power supply with or without rail switching for cooler higher current operation. A popular setup for car audio and professional PA.



Feel free to share your expertise on this matter

Hello all,
I am planning to build a speaker box with front and rear baffles made of 18mm or 25mm MDF (or HDF) and top/bottom/sides made of teak solidwood. Is such a combination would work (both practically and acoustically)?
thanks

Hi there!

LW150-4 6" is not really a sub but there's some bass for my desk. I have 3 idle that I got a while ago, not something I just bought.

What people don't like about ripoles is good if you have them right in front of you. So I gave it a try and I'm liking a lot how it sounds, usually at 50cm from me. Just a prototype using the driver's box.

I wonder if I can use 3 of them for a small 4mx4m living room, listening 2.5m from it.

I was reading a recent thread about simulating a ripole with HornResp. I was wondering if you could model it as a 6th order bandpass. So I took some measurements 2cm from each opening and tried a simulation with the approximate data. It doesn't change much with small variations. I find it interesting that the peak is in the same place. 90Hz is the F3 for the suggested closed box.

Does it make sense to simulate it this way? Just wondering....

I can do measurements 50cm instead of 2cm from the openings later today, right now somebody else is sleeping in this room and I can not measure with more SPL.




This simulation has a 150 2nd order LP filter added. I think this amp I'm using now has this fixed crossover point set, from what I have measured in other tests.




The drive is inverted. No reason other than building fast.

A bit of black foam is separating the back of the driver from the cardboard, hard to see in the photo.

I'm not sure if this is the right place for this. If not please move or delete. I have an old Luxman R-3045 I received a long time ago. When I received it the power IC's had apparently been blown and replaced at one time. The board is Bakelite and the burnt smell is that I really can't use it. It works very well as I have fired it up a few times and the sound is excellent. Now I cleaned everything with 99.9% alcohol with a scrub brush where I could reach and got the rest with a stiff bristle paint brush. and did it twice about a week apart with no noticeable difference. Does any one have a better solution to get the smell out of the board? Mike

Hi. I am repairing a cheap blown amplifier which has two pairs of C5198 / A1941 output power transistors. It belongs to a friend of mine. Previous signs of a repair, someone soldered wires instead of fuses. A couple of 100 ohm 1/2 watt resistors, a 1/4 watt 1k ohm resistor, 2 x 5 watt resistors, A940 transistor, C2073 transistor, D669 transistor, 2 x C5198 2 x A1941 transistors were blown / shorted. The output transistors were shorted on all three pins, very bad since the wire fuses did not blow. I replaced all the damaged items. I failed to get the A940 and C2073 transistors, I got TIP41C and TIP42C, will they work? I also replaced D669 with BD139??? I tested it and it blew both fuses and 2 output transistors. I have tested everything, the bridge diodes, resistors, diodes, small transistors (5551 , 5401) all are fine. But somehow it keeps blowing fuses. There is one item I have not tested, an ic : upc1237 could it be causing this? Let me know. Thanks

Looking for a replacement option in my Hitachi HMA-6500 amp and not able to get specs of the relay on the web. The relay is made by Fujitsu, FRL-264 and D024/04AL -01 are the numbers on the relay.

Omron/TE connectivity and few other vendors seems to have some options on Mouser and Digi key but I cannot figure which one will be a good option and some guidance will be greatly appreciated.

Gentlemen, I need your help.
The volume controller does oscillate at certain volume levels (and always near mute) ~3...4Mhz. Happens without signal, but does not happen when power amp is disconnected.
The MAS and OpAmp (OPA1656) have ceramic and electrolytic capacitors at power lines. Below is diagram from datasheet:



I did not install C213,C214,C217,C218. But I have 47 Oms R201, R202. Will 100p in feedback fix the issue?

Thanks in advance!

Always into learning about audio, done some cabinet building, lotta guitar amp-related stuff. It's all good!
I recently received a AWA distortion meter F2423A, serial number 255 which has some problems. On the web the only service manual available is for serial numbers 586 and higher. And there clearly was an update in schematics, so I am stuck. i hope someone can help me out on this issue.

Hi people,

as it was my first try in DIY-Audio with small budget and mixed chances of success, I deceided to build rather small floorstanders, 2.5-ways driven fully active by chipamps. The drivers are two Gradient W130AL-8 for the midbass and a Peerless by Tymphany XT25TG30-04 ring radiator. Driven are the Chassis by three LM3886 chipamps.
I was really surprised, as the result of my efforts came out really nice, and it sounded, with the help of a subwoofer under 80Hz, for my uneducated ears, far better than expected.
As time went by, I noticed one thing which I didn't think of, when planning the speakers (because of a lack in experience): two 5.25" drivers with a linear max. of 2,6mm will not be moving really much air. Ok, they are loud (more than 50-60% is to loud) and they sound beautiful, but I cannot feel them. I realized this, when hearing such a mobile "boombox" (a bigger one ) and this thing made me feel the kicks of the upper bass in my stomach. Ok, I could build new speakers with 6.5 or 7" midbass, but a: expensive, b: no real tools (except of a router, which I got cheap from the supermarket), which means weeks of work.
As I saw my actual Gradient midbass drivers on sale for half the price, I deceided to cut my speakers open. I'm still far from done, but today I put the drivers back in the first box, and I'm really excited about how they might sound. I expect nothing, as always, but I hope for a little improvement. The two lower drivers will play from 80Hz to 600Hz, the upper one from 80Hz to 2200Hz.. The Speakers measure H: 1048mm x W: 190mm x D: 300mm.
At the moment I'm at putting a fourth LM3886 in the back of the speaker, and I'm thinking about class-D. 4 channels with each about 80W should do it. What do you think?
(before/ after)

best regards
Jochen

Started working on a new USB PC oscilloscope.
It uses a pair of A2D's and 50MHz PIC microcontroller.
I wanted to proceed slowly so I started off with channel 1 A2D IC fitted and it worked a treat.
I added channel 2 A2D and just got terrible noise.
The circuit looked fine to me.
Then spotted A2d on channel 2 enable was always low so making 2 A2D's data buses interfere with each other.
Turned out the A2D enable pin was also used as USB pin.
So disabled it as USB pin.
Still noise.
So back to datasheet on AD876 A2D.
Read it through slowly and carefully until I came across the tri state pin which enables databus output.
Then spotted delay from tri state changing state requires 150nS.
I was expecting just a few nS so that completely messed things up.
So moral of the story is read whole of data sheet first before using an IC.

These days SMPSUs are so ubiquitous and cheap that there really isn't another economical solution to powering a modest power-level amp. However they're all CM noise generators which leads to potential SQ issues with SE input connections as the noise current from the SMPSU travels down the shield of the input cable. An input transformer through providing galvanic isolation helps reduce the noise current substantially and thus reduces SQ degradation.

In this design the input transformer also provides signal attenuation seeing as the TDA8932 in BTL mode has way too high gain (36dB). Added to attenuation there's also SE-bal conversion and the final element is the creation of an input low-pass filter by virtue of the trafo's leakage inductance. The trafo thus realizes four design goals in a single component.

The other point of interest in this design is the use of two regulators - one for the signal supply and a second for the output power supply. Subjectively the regulators make a significant improvement in dynamics - an earlier iteration of this amp used an LC filter to derive the signal supply and there's no doubt that the SQ with the regulator was more enjoyable.

PCBs are due back in about 5 days. I estimate the BOM cost using parts from Taobao to be under $6 but there is the business of winding the transformer to be taken care of. Once I have the PCB working as expected, if there's interest I plan to open a thread in the Bazaar to make kits and finished/tested boards available.


<Update> I've already received interest so here is the thread where the kits are offered for sale : https://www.diyaudio.com/forums/ven...ed-tda8932-25w-8r-mono-amp-kits-new-post.html

Hey guys, I have several different components here for sale, pics to be added soon/upon request.

Faital Pro 8PR200 8ohm (3 available) - £180 for all 3

---

---

Faital Pro LTH102 horn (1 available) - £30


Faital Pro 6HX150 (2 available) - £200 for both

Hypex FA123 (3 available) - £950 for all 3.

Prices do NOT include shipping. Shipping to EU also possible.

Just joined today, currently rebuilding a Laney Pro Tube AOR 50w, hoping to gain some knowledge and advice from users on here.

Also got a Marshall Valvestate 8080 and an Ibanez rack delay il be working on soon too , il share some photos when the time comes.

Thanks!

SOLD

Goldmund Telos clown boards fully assembled and tested

I am selling my 2 completely assembled tested boards of Goldmund Telos “clones”. I call them “clowns” because they are not a copy of the EBay copy attempt of the original Goldmund board. I have modified the EBay “copy “ this way:

1. dual die output lateral mosfet (Alfet) instead of single. This allows only 4 transistors to mount per side which is more easier to implement than 8. All N channels come from the same lot tube. Same for P channels. Added they are double die then internally they cannot be better matched.
2. Use of matched 2SK170Bl for input stage with current biased at about 70% of IDSS. This provides more “triode » sound this way. Refer to Pass Labs forum.
3. Use of metal film resistors. Nichicon Muse B.P. caps for feedback.
4. Use Mundorf caps for PSU. Psu caps and rectifier diodes on amplifier board. Very wide traces for PSU.
5. pcb comes from EBay Jimsaudio and I must admit the layout and board quality is quite good.
6. Output bias current adjusted for 500ma (125ma per single transistors).
7. 100Wrms into 8 ohms (with +/-45VDC supply).
8. Separate supply wires for front end circuit. I recommend about 7VDC higher than power supply output stage. Can also connect front end and power stage with same supply for simplification.
9. THD is quite impressive for 1W to 100W. See curves taken this week just before dismantling the amp.
10. Have been demonstrated with great success during a DIY activities with audiophiles/diyers. It sounds marvellous.
11. I provide the modified schematics For reference since the boards are already assembled.
12. Price for 2 tested assembled boards: 250$ USD

Fab

The BA3884, separates the audio into low, mid and high, dephases the mids -180° and the highs -360° and adds them back. What does this make if it is implied on a three way speaker? Is it maybe a snake oil?

I'm currently repairing my SoundStream Reference 1000sx amplifier and there is an amber colored, semi-transparent sheet that is sandwiched between the huge Darlington array, the power mosfets, and the amplifier's heatsink. I know it works as an electrical insulator and to allow heat transfer, but i'm having a total brain fart as to what the material is actually called. There was also white thermal grease on all the components to help aid in heat transfer.

I'm looking to either replace it with a new piece or if there is another, more modern material that transfers heat better, perhaps i'll use that instead. I already flattened the inner surface of the heatsink for better heat transfer and it currently has a 1200grit surface. So.... comments? Suggestions? Thanks in advance.

Guys

Years ago i bumbled my way around anf FVP linestage. It did not work. It was sent to JoeR and he rescued it. It sounded great. I hardly used it though as life as a 20 year old can change so much.

In the last 12 months i moved from Sydney to a regional town and was blessed with a 5 car garage. So i started to get back into audio.

So the orivional FVP has been removed from service
I have now built a varient of the FVP and SVP with phono stages.

I varied it quite a bit using kandkaudio shunt reg and ccs. I have one per channel.

The SVP sounded a little better than the FVP. With either super reg or the kandk reg.

I ended up using 6922s in phono and 5687 in line. However i have found the 5687s that i have to be very microphonic and very very hot. I am about to try and make the linestage with 6922.

Apart from that i would like to talk to people who have made the phono stage. At the moment i am not happy with it. Relative to the linestage the phono is a little harsh and condensed sound stage. I am not sure i have it setup right. And the riaa has not been trimmed or tested. That is something i want to work on.

I also wish to just try other things and play with this circuit. I have buckets of 5842s, 5687 and 5670 even 5965. All bought 20 odd years ago. I even bought a couple of ec8010 to have a fiddle with. I might even look at an all tube MM phono.

I am also using a khozmo 50k attenuator but not sure if suitable. I do not know if it maintains a constant 50k across the range.

I would love some advice or shared experience on builds. I have read other guys posts and blogs mainly about the linestage but looking for more.

Anthony

A modern interpretation of a classic. Another flat-pak to increase diyers choice.

Fostex BK-12m Folded Horn Kit - Pair: Madisound Speaker Store



dave

Is it possible to open up the Pulse-Lok panel connector of a ML Prodigy to access the 3 wires without cutting the cable up? I need to test bypassing the connector but since it's just a test I hope I can do it in a reversible way.

Hello,
First post here! I arrived looking for info on line arrays. But let me explain my "problem".
Here is my living room/kitchen/office room in my flat (units in cm. 650cm is 31.3feet and 360cm is 10.8feet):

Dashed line are walls which do not go up to the ceiling and there are no doors. So the kitchen is open to the living room and the office room.
The TV cupboard contains the amplifier + TV. Two bookshelf loudspeakers are on top of it at 1.7m/5.6feet above the floor, behind plants, rather close together ... OK not great

When listening to broadcast radio, mostly speech, the setup is OK.
We listen to music at moderate level: the sound comes from a single point and does not "fill" the room. In addition the sound is a bit dull, but after all this not high end equipment. We enjoy music much more in our car 🤣
When watching movies we all are off-axis relative to TV. Main complain here is lack of speech clarity (I am hard of hearing). We do not care about spatialisation/surround as we seldom watch blockbusters.

Ultimately the goal is to have punchy sound that fills the room at moderate level, the clearer the better, and the setup MUST have a high WAF. After all my wife got a lot of things right in this flat so I have to make an effort. Budget is 1k€/$. My ideas:
1/ make 4 to 6 3D printed satellites + 1 3D printed sub (like Hexibase stuff). The speakers would be placed along two walls of the living room (making an upside-down L shape). I can easily hide the cabling, the sub and some of the satellites. I would drive them with my current amplifier at first. I think this is the most appropriate solution in my situation but I know no-one with experience with that.
2/ buy one line array (such as JBL - CBT 50LA 1 in white) and stick it in the corner of the living room + 1 sub. The music experience may be fine thanks to the horizontal beam pattern. TV experience would suffer. I don't know where I could put a second array though. Will that "fill" the room?
3/ buy a soundbar and put it in the TV cupboard. I have read great things about Samsung soundbars including on this site. Problem is bars in the Q-series do not fit the cupboard 😢 . Also I fear they are best enjoyed when sitting right in front of them.

Traditional floorstanding loudspeakers are not an option: no place for them, too low WAF.

Well that's it. Sorry for the long post. Suggestions much welcome 🙂

Sowter transformers for sale

8 pieces for $500 USD Shipped.

Payment by PayPal.

Check my reputation as a seller and contributor on Ebay, GroupDIY, DIYAudio and GearSpace (rafafredd username on all platforms). Buy with confidence.

Selling a collection of 8 pieces Sowter transformers. These are amongst the best transformers ever made for pro audio, on par with the vintage manufacturers like TRIAD, UTC or PEERLESS. Inductance values are amazing, with really low DCR!

Use this on your amplifiers, preamps or DACs for amazing sound and galvanic isolation benefits.

Or, if you are into proaudio, the 600:600 types are good for 1176 FET limiter input, discrete 990 type mic preamp, Spectrasonics mic pre, etc. The 10k:10k types are good for many Vari-Mu circuits, LA2A optical compressor, and nearly any ProAudio line inputs.

All tested and working!

Large size:

Sowter 3257 600 C.T. : 600 SPLIT (150+150)
Sowter 4791 600:600

Mid size:

Sowter 5937 10k:10k C.T.
Sowter 3575 10k:10k C.T.
Sowter 5153 600:600

Small size:

3x Sowter 5571 600:600

DM for details

hey guys, i have a toroidal transformer from a home theater which started blowing fuse all of a sudden.
i found a sticker on the top of the toroidal here is a image of it
.

it is 67W transformer
which has a input of 220v primary
and 3 secondaries which are:
15.5v-0v-15.5v which as thickness as


24v-0v
3.6.v-0v
the remaining above 2 secondary and primary has same thickness


question1: what is the amp for all the secondary?
i found out it can be calculated by W=VA
which gives
4.3225A
2.791A
18.6A for each which iam not sure that its correct!.
question2: is the thickness of the copper wire associated with the ampere?
question3: can i change the thickness of the copper wire by like .10mm or even like drastically ?
question4: is there any alternative way for solving the problem other than doing the trivial rewinding job ?
question5: if rewinding is the only way how many turns should i do and how do i calculate the number of turns ?

Received one unit from a friend for fix on "no sound" issue. After replaced the open circuit current limiting resistors for the pre-amp power supply, now it works just fine.

Out of curiosity, as the amplification circuitry seems a bit 'complex', schematics are reproduced, as a reference for service or DIY build purpose.Only the input buffer and power amplifier section schematics are available.

Big thanks to @osexm, a forum member for his work on the Tempo 1 schematic as it lay a foundation for my reverse engineering work (both design almost identical). All I have to do is just 'double confirm' all the connection.

Some technical details for the Tempo 2:
-signal flow : input relays -> input buffer -> CS3310 -> CFA power amp -> output relay.
-the input buffer which is a diamond, look similar to HDAM-SA2, with different arrangement for the first stage CCS.
-fully DC-coupled from input till speaker output.
-extensive of BC550C/BC560C are used for the small signal section.
-lots of red Wima caps.
-Resistors are mostly 6-band E96 50ppm 1% tolerance, except for higher wattage application.
-standard issue LM317/LM337 are used for voltage regulator for input buffer and first stage of the CFA power amp.
-amplification+volume+dc offset detection circuit and control+other protection+display circuit are electrically isolated using optocouplers.
-dc offset, over temperature, rail fuse detection are available for protection and will display status (in case being activated) on the main VFD display( which is actually a CD player display!).
-speaker output relay does not offer turn-off delay(which actually not needed for Tempo 2, almost silence), but merely just cut-off the speaker in case protection kick-in.

Stipulated: This is an exercise in wretched excess.

About a year ago, I built a string suspended TA which I have been using happily since. In discussions with Carlo (nocdplz), the possibility of a string suspended pivoting linear tonearm came up. I tried an experiment to see if a tensioned length of dyneema would support the weight of the arm without distorting badly. It did. I'd kinda hoped for failure.

A local hardware store carries small pieces of Baltic birch plywood for model airplane building, with excellent strength to weight characteristics, which was helpful because I can only do limited metal work in my shop.

The twin arm geometry is from several years ago and is posted in the "Angling for 90 degrees" thread. All of the pivot points are string - there are no bearings anywhere. The rear control arm is string/magnet/attractor.

The arm actually works well and seems happy with both low and medium compliance carts. It tracks accurately, doesn't skip, allows the cartridge to do its job and the resulting music is quite nice. I haven't done tests yet. The first will be for resonances, which weill narrow cart choice and also show how much difference there is between horizontal and vertical masses.

Doug

Hello everyone, newbie here.

I want to make an art installation, wheras piezo-plates are used to pick up the sound from plastic planes, on which they are mounted on.
The signal needs to be amplified for every small touch to be audible, and until now i've been using mic-inputs from my audio interface which worked fine. Now on a bigger scale i want more active piezos and i really think arduino pre-amp modules would be the way to go.

The sheer option and my lack of experience working with everything arduino are overwhelming. Which one's should i consider and what should i look out for? Every feedback would be greatly appreciated!!

Best regards from Germany.

Hello. I am wondering if it’s okay to run two sets of 8 ohm speakers through this receiver. I have a set of PolkAudio shelf speakers, and a set of Advent Loudspeakers. These would be running in the same room. Is this worth pursuing? Will it damage the receiver? Any advice is appreciated!

I recently completed a pair of mono blocks with Erno Borbely's 6C33C-B SE triode amp, using power transformers from Kenwood receivers and output transformers from Lundahl. I started the project more than 20 years ago. 🙂

A friend is testing one of them for me. So far it has a great square wave and produces 12.5W output across the entire 20 Hz to 20 kHz band.

The power supply is a little funky so I have attached a schematic.

Hello, I want to make some speakers for a large room, 50m2, and I would like a full range design based on mark audio. I need an advice!
Thanks

Hello,

I'd like to build the Mullard 3-3 amp:
http://www.r-type.org/articles/art-003h.htm

I'd like to omit the rectifier tube. But when I use an original power transformer from a EL84 based radio, and the greater voltage drop (from what I saw e.g. 40..50V) vs. silicon 4-diode rectifier is missing, the anode voltages will be too high.
Just adding a higher series resistance is not the same as the effect of a diode - in the former case, the voltage at the tube anode will more directly depend on the current going through it.

How would one do this?
... save from trying to obtain a transformer that gives just the right voltages. I might have another one, where the seller claimed it has curious 259V output, still a bit high vs. 250, but it's a start...

Then there's also the us having 230V today, where the transformers are for 220V, adding to what I need to reduce (if I don't want to age things prematurely).

Hello, was listening to some streamed music this afternoon. The amp is a Separo amp that has 4xKT88 ouut valves. I was doing my ironing when my wife came in and said, “what’s that smell?”. At first Ithought it was the iron but I looked across at the valve amp and on of the KT88s was glowing much brighter than the others. The sides of the tube were going black too.

The volume was inly at 10 o’ clock bit I switched the power off immediately. So what do I do now? Is it likely to be one valve failing or is it likely to be something else? If it is just the valve, can I just replace it with another KT88 of the same make (Genelux) ordo I need to replace all the KT 88s?

How do I proceed from here to see whether it is just the valve failing or possibly the transformer or something else? I’m reluctant to even turn it on again before I receive advice. Thanks all.

thank you all .I have covered

At this moment I am testing a function generator from UNI-T, the UTG962E.
It has the advantage of having 2 output channels which parameters can be set individually.
I cannot detect the possibility to synchronize those 2 channels. For instance, I want to have
the possibility when changing the frequency, both channels will change to the new frequency.
Is there a function generator which can do this?

Hi, On my schematic, in the bias section, there are those two diodes array. The STV-4H are represented by 4 diodes and the STV-3H is represented by 3 diodes. Is it really the case, if yes, what kind of diodes could have approx. the same temp variation. Or could it be replace with another thermistor having a PTC (positive temperature coefficient) that could be glue to the heatsink. If I replace them with standard diode like 4148 or 914, do I have to put 4 and 3 of them in serie. Thanks for any advice.

Hi all DIY hifi lovers!

Just 2 days ago I have aquired an old Krell KSA250, sold as defective.
It turns out that the soft start board (mostly the capacitors on it) is toast. Working on that now.

I'd like to switch the unit from 220V ac to 240V ac. Could anyone help me with the correct position of the 2 switches for 240V ?

Also: Given the arrangement of the loudspeaker terminals, mine must be version 2 or 3. I have Googled a bit but can't find any information on the differences between the 3 existing versions.
It would be great if someone could lift this curtain for me.

Warm (when the amp works "hot"!) Regards from the Netherlands,


Jacques

Hi

I am planning my first meh horn.

What is clear to me is the position: position should be max lamda/4 from next diafragma of the tweeter and ports should be in the corner's.

But what about port size und port form? I found somebody who said: size max ~1/8 of SD is this correct?

In my case it could be necessary, to make the ports a bit longer and diagonal, to make sure, that i keep the max lambda/4 rule.

Is it OK to drill the holes not 90° into the plate?

I have attached a picture. The red part is a diagonal port. Frequency range would be 100Hz to 500Hz.

Thx a lot and greetings

Christian

Hello everyone on the forum!
I am a new member and I write from Sardinia.
In my city there are few technicians and therefore I decided to "specialize" in repairs, even if I'm just starting out!
I find myself with this hiwatt t40 combo with numerous problems.
listing I don't have the negative voltage of the bias in pin 2 of the el84, so when I mounted a new set of el84 tubes I immediately noticed red plate.
furthermore this amplifier has a diode bridge on the filaments which tends to get hot.
I honestly don't understand how it was designed or at least this is very ambiguous.
Since the wiring diagram is not available and they never reply on the hiwatt.uk site, I ask you for a huge help.
I find myself in the position of not being able to repair this amplifier.
I tried to follow the diagram to have a logic, but I don't know why there is no negative voltage of the bias and because the graetz point heats up so much.
thanks if you can.
Sorry for my english.
Caesar

Hi…is there a 6” 4ohm driver that can play in 10-12liters?

Tnx

There are 6 different LM1875T listed on Mouser including in stock: LF05,LB05,LF02,LB02,LB03. Please help me find the meaning of these suffixes.
The LF05 has .005% less THD than the others. They vary in price. These factors don't matter for this order.

I soldered a strip board with LF02. It worked well with single 19vdc supply. Now I working on a tidy version.

Hi, I have started my first speaker build and would like some help.

the idea looks like this, the speakers will be big, 4-ways, they will have active crossing with built-in final stages from icepower.
the construction will look like wwmtmww

the speaker elements that I currently have are:

2x Tweeter: Vifa XT-19 4
4x midrange: Dayton audio RS100 8
4x Midbass: Dayton audio RS225 8

I would like to have subelements that cross roughly around 60-70. I have been looking at the dayton audio RS210 HO/HF. How would two of those work in this setup?

How does the whole idea seem in general? disregard the cost issue, it has no bearing in this case. What I'm interested in knowing from those of you who are pros in the case is if it works?

My concern with the sub elements is that the sensitivity is so different to the other elements, how do you compensate for this?

sorry if the english is a bit weird, i had to use google translate.

Wanting to buy pair of seas t35c002, give me offer if you have one to sell.
Preferably from inside EU, but willing to consider also outside of it..

What is the actual material composition of the contacts inside Neutrik SpeakON connectors? They look to be a silver metal, possibly Nickel plated Copper. Anyone know?

Hi, I got my new oscilloscope up and running. Tested the Vac with an 8ohm dummy load resistor. Made some basic measures and took screen captures (see below).

1. The first image is a sine wave (1Khz) at about 0db (from the AVC) and as you can see, the bottom of the wave is doing something funky.
2. 2nd image is the same input/output levels except a triangle wave form
3. 3rd image is the same input/output levels except a square wave form

My system is a streamer (2V output) --> autoformer volume control --> amp. The sine wave form is clean until about -3db on the autoformer, then the bottom of the wave starts to flatten (as evidenced in the image #1). As the autoformer volume control moves up to a maximum of +5db, the bottom of the sine wave form flattening gets worse. So, I need help interpreting these images. Is the issue with the power amps, AVC or streamer?

Schematic of my amp is attached. This is the 35T SPUD/OTA experiment that I am running. BTW: the sound is wonderful at low and medium loudness. But once the AVC is at -3db thru +5db, the sound gets distorted. This correlates with the scope measurements. I am getting a 14K OPT to replace the 5K OPT, as this should help the bass which appears to be much of the distortion.

Any input would be appreciated.

Hey folks, I have some ready to crossovers for the Pit Viper speakers by Paul Carmody. The PCB's were made by Matt G (you all know the one, what a great guy). I made some modifications to my driver layout that unfortunately proved to be a little too much for the crossover and haven't had luck altering the xover parts to appease my layout.

I'll ship them to your door for $60.

A long shot I know , I’m trying to get a Philips cd207 working.



Thanks

Hi,

Could someone please confirm what the big picture general arrangement to drive a pair of SS Icepower Monoblocks with a tube preamp from a turntable phono signal? Looking to only use tubes and no solid state up until the poweramp input. Assumption; SS Amp has 10K impedance so preamp requies <1K impedance.

Example 1. - Preffered but cannot find design
Phono MM or MC cartrige > Class A Single End Tube Preamp (impedance <1K) > SS Monoblocks (10K impedance)
Can anyone recommed any Class A Single End preamp designs with an impedance of less than 1k that accepts a RIAA input?

Example 2.
Phono MM or MC cartrige > RIAA Tube Preamp > SS Monoblocks
such as http://diyaudioprojects.com/Tubes/RIAA-Phono-Preamp/

Example 3.
Phono MM or MC cartrige > Tube RIA converter > Class A Single End Tube Preamp > SS Monoblocks
I found this design but I think it does not accept a RIAA phono input
https://www.cascadetubes.com/the-12au7-cathode-follower-color-preamp/

Hi All ! Long time to see.😆
1、315V 330uF 30x35mm 105C Snap In Capacitor Lelon LSK331M2F--A3035（50pcs）
https://www.ebay.com/itm/234973151726
2、50V 470uF 16x16.5mm SMD Capacitor Lelon VEJ471M1HTR-1616（200pcs）
https://www.ebay.com/itm/234976089271
3、25V 100uF 8x10mm SMD Capacitor Lelon VEJ101M1HTR-0810（500Pcs）
https://www.ebay.com/itm/234976105848

I'm looking for a magnavox 8802 or 9302, something complete, not too ugly, even without tubes but above all that doesn't cost me a kidney and an arm.
of course the American market is full of them, but the shipping costs and customs fees greatly exceed the price of the amp alone.
it's not urgent, it's just amps to play and have fun.

I am building a clone of boenicki w5 with these driver:-
Tang band w5
Founteek FE85
Dayton TD20F

Can anyone help me with the crossover schematic for this setup. Please 🥺. I am attaching few schematic of which i found online with different tweeters.

I'm not going to pretend that I really understand this subject, but I'm intrigued by the idea of Zobel networks and would like to learn if it would improve my speakers, which are currently leaning toward a harsh top end.
They are small T-M-M towers, with the 25mm silk dome CSS LD25x XBL tweeter above a pair of CSS LDW7 7" midwoofers, crossed at 1800Hz. Crossovers have good quality components by Erse and Jantzen.
Actual construction of a Zobel network seems pretty simple, but I don't really understand how to design one that's right for my speakers. Can anyone help?
Thanks!

Hello everyone!.. i have this driver (b&c ps32) and i am thinking of building a sub ,specifically a horn type. I have built mth30s in the past, with great results, using ps32's smaller ''brothers'' the pz32's. I have seen martinsson's roar 12 sub plan, i find this very interesting design. I have done some reading and it seems that this design have some opposers , maybe it needs sove development maybe not, so it can reach the success of the mth30 or the tham 12, tham 15. I am open to ideas of course, since this site is a huge tank of knowledge with people that they really love what they do. thanks in advance and KEEP BUILDING....

I am writing this for the benefit of any Australians using this forum. It is now illegal to own sell mercury vapour tubes including 866 and 83 rectifier tubes in Australia. Included is a picture of a tube I handed in today, 17 tubes were sent to Northern Adelaide Waste Management, many of the tubes were brand new. Also included is a notice from a radio club magazine.

https://audioxpress.com/news/hypex-presents-new-nilai500-diy-audio-amplifier-module/

dave

I have a few spare PCB's. These are extra boards which I have left over from a fabrication run (due to minimum order requirements) and are therefore sold for DIY purposes only and not for commercial gain. They are to cover board, build and shipping costs to me, not for profit. Once they are gone, they are gone.

PAYMENT AND SHIPPING:

• Payment by Paypal "Friends and Family".
• UK - Free untracked P&P for orders over £5, additional fee for Signed-For.
• EU / USA / Rest Of World - As per Royal Mail: Get a price | Royal Mail Group Ltd, additional fee for tracked.
• Payment within 48 hours before being released from reserve.
• Please reply here followed by a pm if interested.

Die-Noizator 5-36V Linear PSU, PCB designed by me, schematic by Elvee/diegomj1973
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Single rail positive PSU 5-36V.
Onboard transformer solution (Talema/Amveco/RS Pro toroidal series).
EMI filter, transformer snubber, CRC, LM317, Sziklai Pair Die-Noizator. Extremely low noise PSU.
These are my latest revision (2.1) with compatibility with 110V or 240V mains voltage.
Transformer secondaries can be jumpered parallel or series.
None available £7 each, 100g 'Letter'

• 2x kcom00 (AUS) Dispatched 20th August
• 2x jimk04 (UK) Dispatched 20th August
• 2x mgb1965 (GER) Dispatched 20th August
• 1x sq225917 (UK) Dispatched 7th September
• 1x Mituisho (UK) Dispatched 13th September

Die-Noizator 5-36V, PCB designed by tombo56, schematic by Elvee/diegomj1973
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Single rail positive PSU 5-36V
Offboard transformer.
None available £4 each, 100g 'Letter'

• 2x kcom00 (AUS) Dispatched 20th August
• 1x kffern (AUS) Dispatched 20th August

Objective 2 Headphone Amplifier designed by NwAvGuy
NwAvGuy: O2 Details
7x available £8 each, 100g 'Letter'


Passlabs ACP+ Headphone / Pre-Amplifier Clone, PCB designed by withmatt
Amp Camp Pre+Headphone Amp - ACP+
None available- £12 each, 200g 'Letter'

• 1x mgb1965 (GER) Dispatched 20th August
• 1x Peppe (SWE) Dispatched 1st September
• 1x Piisami (FIN) Dispatched 1st September
• 1x M_Balou (GER) Dispatched 1st September

MOD: Mini Output Delay for Headphone / Line-level Audio designed by me
MOD: Mini Output Delay - a headphone / line-level audio output delay retrofit PCB
A miniature 2x3cm retrofit board to protect headphones from turn-on/off power transients.
12-35V power input. 0-30 seconds adjustable delay time.
10+ available £4 each, 100g 'Letter'

• 2x mgb1965 (GER) Dispatched 20th August
• 2x Gregje (UK) Dispatched 10th September
• 2x Mituisho (UK) Dispatched 13th September
• 2x SigFire (GER) Dispatched 21st September
• 4x s666foto (NED) Awaiting Payment

Ground Breaking: Earth Loop / Audio Ground Isolator designed by me
A 2x3cm board that helps reduce hum in audio circuits that are attached to a mains earth connection.
x5 available £3 each, 100g 'Letter'

• 2x kcom00 (AUS) Dispatched 20th August
• 5x truepaul (USA) Dispatched 26th August
• 2x Neat Ripple (UK) Dispatched 28th August
• 2x Slinkymalinky (UK) Dispatched 4th September
• 2x avinunca (UK) Dispatched 5th September
• 2x sq225917 (UK) Dispatched 7th September
• 2x Mituisho (UK) Dispatched 13th September
• 2x SigFire (GER) Dispatched 21st September

Alps RK27 Blue Velvet Breakout / Mounting Board designed by Nisbeth
A breakout board for mounting Alps RK27 volume potentiometer.
10+ available £3 each, 100g 'Letter'

• 2x Neat Ripple (UK) Dispatched 28th August

8-Pin SOIC or MSOP/(T)SSOP to DIP Adapter
A miniature board to mount SOIC or MSOP/(T)SSOP integrated chips into DIP sockets. Perfect for op-amp rolling.
10+ available £2 each, 100g 'Letter'

• 2x mgb1965 (GER) Dispatched 20th August

CheapModo Snubber Calculator designed by Mark Johnson
CheapoModo: quick and dirty transformer snubber bellringer jig
A quick and dirty transformer snubber bellringer jig to calculate optimum snubber resistance values.
None available £4 each, 100g 'Letter'

• 1x kcom00 (AUS) Dispatched 20th August
• 1x M_Balou (GER) Dispatched 1st September

I have a pair of old speakers in which one of the C8MX drivers has failed. For nostalgic reasons I am hoping to restore them to their former glory...

The speaker has 57/8 stamped on the frame. The 57 refers to the cone material (F57) and the 8 refers to the nominal impedance (8 Ohms).

If anyone can help with a replacement driver I would be grateful.

...any of you use a mono OB speaker in your regular system? How do you think it compares to stereo OB or stereo box speakers?
I want to build a speaker similar to Reflector Audio P18 (but with a coax in place of the 2" compression driver). Two of those and the associated active amps and cabling would be unbearable in the living room. But just one is doable 🙂🙂🙂

I'm pretty new to higher end stuff 🙂 I have a pair of Energy Veritas 2.2 which have dual voice coils in each 6.5" woofer. The woofer is 3db down at 40hz (ported cabinet) and crosses over to a 2" aluminum dome midrange at 550hz. They are pretty transparent in the mids (edit: including the lower midrange spectrum that's covered by the woofer).

I'm planning on running them with a servo sub, crossed over at 80-85hz. The two voice coils are connected internally, so there are two wires brought out to connect to the crossover. Dual voice coils are supposed to help lower distortion at low frequencies and are used in some subs. I've seen dual VC midrange units for high power car audio, but I haven't found anything yet in the mid-high end audiophile market.

Here are a few details in a review of the Veritas 2.4 (3 of these mid/woofer units) from https://www.soundandvision.com/content/energy-veritas-v24-surround-speaker-system:

"The Veritas V2.4's 6.5-inch woofers have dual voice coils wound in opposite directions (thus the designation Dual-Hyperdrive). Each coil is situated in its own magnetic gap; operating them in tandem is said to significantly reduce distortion. The cone is made of a special composition designed to optimize weight, stiffness, and damping. A phase plug of solid aluminum eliminates the dustcap—a possible source of coloration—and helps dissipate heat."

So would a dual voice coil setup also improve the accuracy of the lower midrange? Or is it just mainly for the bass region?