I have fired up my SSE and there are a severe hum in the speakers, I still hear it when I leave the room with the door open.

This is my first build and the setup are:

• Power: Hammond 374BX
• JJ 5AR4
• JJ 12AT7
• Russian 6L6GC equivalent (see pict)
• OPT: Edcor GXSE15-8-5
• No choke, R1 = 150 Ohm
• Speakers: No name 8” + 1” tweeters from the 1995-isch.

The amp are now configurated in triode without feedback (see pict)
The board are grounded via the PCB together with the zero point of T1, the center of 375-0-375.
Incoming signal are grounded via the PCB at the IN-connectors (pin 2 & 4)
Speakers are grounded via the PCB at connector T2&T3 sec
I have not grounded the power and OPT shields, it is on my ASAP to-do list.

Measurments:

• B+ = 454 V
• R17/R27 = 680 Ohm, wired to the outside of the PCB for easy exchange during the test period
• U_R17/R27 = 35 V
• I = 35/680 = 52 mA
• P = (454-35)*0,052 = 21,5 W
• VAC in idle on the OPT-sec are 24 mV on left channel and 54 mV on right channel, measured with my DVM.

My oscilloscope are not sensitive enough to measure mV and are only rated for 50V. Will try primary side of OPT with DVM before I hock up the oscilloscope on that side.

Things I consider to try out, in specific order

• Ground the casing of transformers
• Twist power wires (5, 6,3 and 375 V)
• Add a capacitor at T1 red/yel-GND

Will negative feedback help?
Shifting the sec of OPT?
I’m considering a choke. However are this related to cost (I have already exceeded my budget) and lead time, if I order today will I not receive it until next week, the weekend will be spoiled. Therefore is this not my primary solution, more like a backup.
Anything else, what have I missed?

Have recently bought some old Tannoy 613s that have seen better times.. Checking them over and comparing I have noticed the wires dual concentric drivers have been re-attached differently for each speaker. I don't know which, if any, are correct! I have searched extensively online with no success of the internal wiring.
Could anyone please advise me, or guide me to a logical result using the crossover. I am not very experienced with electronics.
Thanks

I am looking at building a 3 way speaker but wish to change the bass cabinet to slightly smaller size.
The design I am looking at uses an LCR circuit on the midrange unit and on the bass unit due to a low point of crossover and I have been told that if I change the bass tuning ie box size and port tuning that the LCR circuit would have to be changed also.
I dont know much about that sort of thing and although I can see that it may change the LCR circuit on the bass unit I assume the mid circuit would stay the same.
Also if I were to build it sealed I assume that the LCR would still need to be changed or am I wrong.

I've got a question about replacing the attenuator in the following circuit from a Denon pra1100 preamp. I like the preamp, and it sounds good. I am curious about changing out the attenuator, however it uses a 4 gang pot that is really 2 different pots with different resistance. The first pair, is atte50k and sits before the flat amp and tone controls. The second pair is 5k and sits before the buffer.

My question is, why is there a 5k attenuator before the buffer?
Because the attenuator pot is 2 different resistance, a replacement pot is not available that I can find. Maybe I should leave it as it is, but I can't understand why it is there, or needed... Could it be replaced with a resistor in the middle of the range? say 2.5k in line, and 2.5k to ground?

Thanks for the info... I'll probably leave it alone, but I was toying with the idea of putting a higher quality attenuator in, say a 50k alps blue velvet, just to play around with it.

My unit doesn't seem to have the cd direct input or relay 601.

Here is the circuit diagram.

Dear all

I am currently thinking about building a GU-46 push pull amplifier (two monoblocks).

As OPT I am thinking about a 5k Ohm 200W transformer, custom wound by ogonowski.eu, he already made several transformers for me. I am very satisfied with the quality of his work.

Can anybody comment in the impedance of 5k Ohm for a push pull OPT for a pair of GU-46? I have seen one other (russian single ended) project using a 5k OPT.

Intended anode voltage 1000-1100V (0.5A), grid 2 600V, neg. bias around -120V (to be evaluated).

I think about using the following set up for loading of the GU-46
First stage: phase splitter 6SN7
Second stage: for each phase a 12hg7 voltage amp (something like pmillet)
Feed into GU-46
I plan to use coupling capacitors between each stage.

I have not yet decided on the PSU.
The high voltage cirquit for the GUs shall have its own transformer (approx. 800-0-800V 1.2A), the rest of the tubes shall fed by a smaller (approx. 350-0-350V 0.3A, 6.3V CT for the heaters).
The heaters for the GUs requires 8.3V at 16A for a pair (will need to be decoupled in pp) coming from an LED Power supply most probably. The negative bias will have its own transformer (approx. 100V 0.3A).

I would love to use paralleled mercury rectifier tubes for the high voltage rectifier, but this would need additional iron. Alternatively the use of bridge rectifiers at 1600V/30A or so could be used. The lower voltages shall be rectified by one 5U4G per block and the neg. bias by diodes.

I have not yet drawn a schematic, but would be very interested in your professional feedbacks. This Project is a bit bigger than all I did before, early Input is very welcome.

Greetings from Switzerland.
Thomas

Hi,

I'm working on the amplifier of a subwoofer (Energy S8.2 , ~ 2002 build date)
(Mods, feel free to move if there's a better subforum)

The amp is fixed now, but I was curious to see how it was designed (class AB MOSFET amp, and an unusual transconductance amp LM13700 !?) so I traced some of the PA board.

I'm not done with the feedback network that involves the LM13700, but the power section should be complete. But part of it is making zero sense to me, despite rechecking the PCB multiple times.


T11 and T9 , current mirrors ?
D15+D16 mounted on the heatsinks, which in conjunction with the pot P3 look a lot like a temperature-compensated bias adjustment.

I can sortof see a kind of differential amplifier combining into T5, but the whole bottom part doesn't work.
T12 tells me "current source", but there's nowhere for the current to go !? Certainly not into T14's gate, and not backwards through D901...

It is not impossible D901 could be a zener (I could only read the last 2 digits "..48" on the glass body so I assumed 1N4148) but that doesn't make any more sense.

Is there anything obvious I overlooked, or some area I should review ?
Or if anyone has a "correct" schem of a similar topology that I could look at for inspiration... but it can't be that hard, this is a 2-layer through-hole PCB...

Before take on my main steer speakers rebuild, I thought I'd have some cheap experimental fun with my desktops and play with time alignment on a flat baffle.

I have not seen reference to the Bridged T filter being used. Only comments on the all-pass phase filter. Nor have I seen any handy-dandy WEB calculators for either.

Any experience?

Hi! I need some help with building a balanced 2.5kHz highpass filter as a inline filter for my Xlr power amp. I have a Tpa3255 which have 20kohm input impedance. Source has low impedance so it shouldn't matter. I put in some values into a online lowpass calculator with 20kohm impedance, and it said that I needed a 900mH inductor?! I know I need 2 inductors(one on each conductor) and a cap in paralell with the input. If someone would bother to check the values or point me to cheap source of the such an inductor that would be great!

I'm contemplating this kit:

JDS Labs - 3-Band Equalizer DIY Kit - DIY Kits

It appears to be able to support minimal mods:

Electronic Projects: JDS Labs Subjective3, Part 2

I've attached a schematic of the tone control "stack" as utilized by JDS Labs as well as the same schematic from the TI documentation for the OPA227 op amp. My questions are as follows:

1. What type of "tone stack" is this? It appears to be some kind of modified Baxandall?

2. I want to change the bass frequency and, with a conventional Baxandall circuit, this can be accomplished by changing the capacitors associated with the bass control. There appear to be no caps associated with the bass control or I am missing how this configuration operates.

3. Is there a LTspice model for the OPA227?

Hello - I am new to the forum and weeks of agonizing over which amp to build for my system has led me here.

I recently moved to a condo so I won't be able to blast the music like I would have been in the past - however, i'm taking this opportunity to focus on better sound quality. I figure 10-40 watts will be enough.

I looked at one of the popular Pass DIY's but I don't want to chase down unobtanium transistors...

Are there any well regarded, low power Class A or Class AB kits, boards, schematics, that use parts I can buy off DigiKey?

I have an AliExpress LM3886 board coming, which I suspect will I will toss in the bin.

Extra info:
I currently have a pair of JBL 4307s which are rated at 6 ohms and 91db sensitivity. They're being powered off a Sony TA-70 which goes plenty loud for my needs but I find that the bass isn't very tight which I'm guessing is a lack of damping factor with the integrated amp. To me bass tightness is important as I listen to a lot of house music and indie pop.

I have an enclosure for a Pioneer TX-500 tuner which I am going to hollow out and stuff an amp into and add VU meters. I have another Sony TA-70 which I'm converting into a preamp using a simplified (unnecessary parts depopulated) output board from a Pioneer DJM-500 mixer, and taking the power supply outboard.

Some odd choices here I know, but the goal is to have a nice looking, good sounding stereo that fits in an IKEA Kallax shelf

If sound is the main preference. Which is the best amps?

I have up to 30V available and it isnt neccesary with three figure watt. +/- 30 watt in 8 Ohm is enough.

Selling at US700 (not include shipment)
good condition and good sound
can ship worldwide

If interested, Please PM

hello there!

just recently i cleaned and recapped my inherited marantz 2270.
everything seems to work just fine, i sounds just great..

except that the speaker protection relais does not react propperly.
as i replaced the caps (with same uF-ratings but slightly higher V-ratings) on the power supply board -which seem to define the timing of the relais- i do not know how to fix this. i just dont have enough background to do the maths.

could someone please help me find a clue and or solution?

thanks in advance

Got here from Nelson Pass's video on the Audiophiliac, and boy is the DIY bug stirring within ever since!

As a first project, I decided to upgrade the crossovers on my Paradigm Prestige 75f's to DIY ones with higher quality components with stock values.
Some preliminary questions:
1. Any tips for reverse engineering the board using a continuity meter?
2. After the schematic is in hand, how do I choose between the different caps\coils\resistors brands and models?

Since this is my first time DIYing crossovers, any relevant tips will be appreciated.

Thanks in advance 🙂

Hello DIY Community

Let me introduce my pet project, I have been working for while. SlimStreamer (GitHub - gimesketvirtadieni/slimstreamer) is an audio streaming software for Linux with multiroom functionality. SlimStreamer captures audio playback from ALSA and broadcasts it to connected Squeezebox devices (real or ‘virtual’ like squeezelite) through SlimProto protocol. Moreover, while capturing, original sampling rate is preserved and PCM stream does not get resampled to a predefined frequency. Other solutions (like AirPlay, SnapCast, ...) use predefined sample rate, so original PCM stream is resampled in case sample rate does not match.

In other words, you can use any Linux software that outputs audio to the default ALSA device (MPD, Mopidy, Spotify client, ...) and SlimStreamer will capture it and redirect to connected Squeezebox players (for example squeezelite) in a transparent way.

I am still working on supporting SlimProto (it is still missing). However most tricky part, PCM capture in a bit-perfect way, is working fine, also single-threaded asynchronous TCP server is done.

Few more details:
-> SlimStreamer is written in C++17 (one should read it is very fast and lightweight)
-> It uses two ALSA plugins: SlimPlexor (GitHub - gimesketvirtadieni/slimplexor) and Loopback (Matrix:Module-aloop - AlsaProject)
-> SlimStreamer's source code is in Public Domain (Unlicensed)

Any comments / feedback about whether you find it relevant / interesting / useful are much appreciated



gimesketvirtadieni

Up for sale 45 samples of EF86 Tesla, new in original pristine packaging. This is probably the earliest version of it or around 1962, similar in construction and materials to Telefunkens.

Singles - 15 EUR + shipping
Quads - 50 EUR + shipping
Octets - 80 EUR + shipping
The whole lot of 45 - 400 EUR (shipping included)

Payment by PayPal Friends and Family or bank transfer, your choice. Payment can also be done in USD at the spot exchange rate.

More pictures and information available on request, but for that I kindly ask for a WhatsApp or Telegram mobile number to facilitate the communication.

Have plenty of other collectible tubes of US and EU origin.

Cheers!

i have just now recieved a pair of these and am intent on making a pair of bookshelf spkers using them, however i have been unable to find ANY specifications online and aurasound have been unable to help.

has anyone here had any expereince with them and any info they could give me on their specifications???

I recently purchased and received parts from a Russian seller of KP926B. The curve tracer says that they are all genuine SITs.

The reason I am interested in these parts is for the 400V Vce. They may serve well for an electrostatic headphone amplifier.

They devices are widely different from each other. You would need a large population to obtain a matched quad. Even one matched pair will require quite a few devices.

Up until just recently if anyone had told me that rectifiers sound differently I would have responded with something to the effect that they were crazy. But, I swear they do have different sonic qualities and no I haven't been drinking. I first thought I heard a difference when I experimented with different rectifiers in my 6SN7/6SN7 Aikido P-to-P line stage. I started off with a home made SS plug in rectifier and then progressed to a 5Y3. I thought the
SS sounded a little punchy. I then tried a 5AR4 a JJ that I had handy and then a Japaneese Mullard 5AR4. The Mullard sounded better. Then I tried a Chinese 5Z4P and it sounded really smooth. Then I tried a #80 in a octal to 4 pin adapter and it sounded the best of all.

I ordered (2) #83's to try.

So, the question is am I right? Do rectifiers really sound different. Even the wife admitted she heard some difference after telling me just play the damn thing.

I also tried different rectifiers in my Stereo 70. The Japaneese Mullard first followed by the JJ followed by the SS plug in followed by a 5U4. To my ears the Mullard sounded really good followed by the 5U4. The 5U4 has a really nice smooth midrange and this is after setting the bias to the correct setting because it was lower with the 5U4 than the 5AR4.

Am I totally nuts?

Tanks to smms73 I can show here novel Error Correction circuit used in Non GNFB class B power amp.
I tried before with classic Hawksford Error Correction, but with not so good result as with th is novel EC. I Think that smms73 came to this idea by himself, an latter has found that this is also already presented by Hawksford.
The THD can be seen on the schematic.
This is not ready to be used as a working amp, as it needs to be more simulated and improved in some areas.
BR Damir

Hi everybody, first post on here -happy to join the party!

I have an issue with my Fostex XR-7 multitrack cassette recorder that is driving me nuts and I was hoping the collective knowledge on here might be able to help. I would be incredibly grateful!

In the middle of recording yesterday it suddenly stopped recording/writing to the tape without any physical indication that it had stopped. The record indicator still lights up, and all meters show as if it is recording, but when I listen back to the tape nothing has been recorded. This happens for all tracks, and across different cassette tapes I've tried.

I opened the unit up and did not see anything immediately obvious:
-no snapped off/unconnected wires
-no obviously loose solder joints
-no burnt or exploded resistors or caps

I'd be happy to post detailed pictures, take voltage measurements, etc if that will help. Any advice is appreciated!

One pair of 10.3 new sealed in box will sell or swap for 10ps i have a set of xls with 10.3 in and would like to try the p as well this was my second pair of drivers that i was going to use for another project now not going ahead. Based in the uk

Make me a sensible offer

Who know the pdf download area for schematics of this manufacturer or can upload this schematic?

Thank you very much.

For sale 2 pairs of 2SK60/2SJ18 all in the same 55 rank.

I subscribed to this forum since my Sony Ta-5650 failed. I bought it about 25 years ago secondhand, I later found out that the precaution upgrades were made so I did not worry.Unfortunately now 4 of the 8 vfets are gone and I don't really have time or money to do something about it or even build a push-pull triode's amplifier.
Only thing I know that these are really hard to get these days.


I tested the Vfets according to Service Bulletin No.62. I do not have the equipment for deeper testing but according to registered user soundhappy they should be ok if they pass the diode test.


If you happen to be from Switzerland you can come and test them in Zurich.
Or I can redo the (limited) testings on a whatsapp video call.


I am selling them here because I think they will be in good hands then.


I really need some money because of the covid disaster, so price I ask is 250 € + shippingPayment with PayPal.


included:
- the 4 good Vfets
- 8 original thermo spacers (only four used), two of them are not so nice but probably ok, see photos
-16 original screews (only 8 used of course)



First person who PMs me will get them.


Cheers

My TEAC VRDS-10 is refusing to read a few discs - most notably hybrid SACD/CDs and CDRs. The problem seems to affect more discs when the player is switched on from cold. After a few minutes warm up some of the affected discs will then be read and will play OK.

The player had a full service two years ago, so the laser should be OK. Please can anyone suggest what I might need to look at first to solve the problem?

John

I began this project aiming for better lower midrange.

I was having lunch at a club, and in the room was a drummer tapping a cymbal. I noticed I didn't have to think about it.. below 1kHz was there with the treble with the same acoustic sense. I don't get this from most speakers, there is a fatigue element in deciphering the inconsistent reflection pattern. A common problem is usually near and below the baffle step, as this is where most designs decide to allow the sound to go free.

I've long tried to bridge the gap so there is no baffle step. This is not easy, but when done right it comes with the benefit of consistency that eliminates the room in certain different ways.

Being in the corner has multiple advantages, as well as significant disadvantages that are difficult to overcome. Hence most speaker builders build for placement into the room... It allows the room to be used to aid in directivity that helps bridge the region where the most variation usually happens. It also offers the widest stereo separation available along a wall, as well as the longest early reflection delay times.



The B&C 8PE21 is efficient and suitable for horn loading.



Cymbals reach down to the low hundreds of Hz and are a good test IMO as the above and below 1kHz region needs to have no interruptions. I've had baffle region improvements in the past by adjusting the reflections with speaker position and EQ, with a lot of absorption. The sound was generally good and less fatiguing, but I wanted to take it further.


* Midrange phase plug

Corner placement has a later far side, and floor or ceiling reflection and can negate the other three walls. Stereo separation is increased and each speaker is toed in front of the listening position.


* The toe-in, and the approximate centre depth of the soundstage.

A multi-way system
I've been listening this way for about a year. At first the midrange would come from above the tweeter. Fixing the crossover blended them but the source sounded elongated. I damped some resonances in the mid horn walls and have also changed the vertical profile, now mono sound locates strictly between the tweeters.

Now I can walk up to it. The region away from the middle is silent.


* Adjusting the midrange horn profile.

The rectangular cross-section on the mid horns helps at the room walls and makes them easier to build. They have a slow radius before offloading to the walls.

The tweeters are more narrow, and elliptical with a mouth radius before going back onto the wall.



I designed the tweeter horn to meet the mid at 700Hz. The vertical profile is narrower but longer, as both dimensions hold their directivity down to the same frequency. I then interpolated it to be ellipsoidal.

The woofer is baffled out of the corner but I want to push the woofer acoustic centre back. Behind the speakers and along the back wall has been lined with 100mm acoustic rockwool.

Tweeter

* Before using expanding foam.

The vertical profile is 45cm long, horizontal 30cm. The mouth width after the first roundovers is about 75cm around the ellipse. They are intended to be OS but I needed to interpolate some of the profile.

The tweeter and mid cross while around 80° H x 60° V.


* Rear view of the tweeter.

Acrylic (plexiglass) was used for the first 36mm. The next 20cm has a solid wooden outer layer with the profiles formed over this. At the start they are filled with plaster and further out by using ply and expanding foam. At the edges I'm using poly floor mats with rockwool packed behind them.

The driver is the B&C DE250.



Midrange
The horizontal profile is hyp-ex, and vertically they are T=0.8 LeCleach. Efficiency is around 107db/W/m.



The first part of the horn and the rear enclosure have been made from 36mm MDF. I used two 18mm sheets for this so I could have a constrained layer of PVA glue. The later parts of the horn use a plywood outer former with thin ply used for the profiles which I have filled with expanding foam.



The B&C 8PE21 is well made. I'm using a compression ratio of 3:1.

Woofer
This direct radiator was a part of my old system and uses the Eminence Delta15 in a closed box. These are around 96dB sensitive and can be EQ'ed to any response I need.


* The cabinet uses CLD, hardwood bracing and flexible driver mounting.


The best crossover frequencies seem to be 270Hz and 800Hz.


* A random crossover measurement including tilting of the treble.

The midrange horn is spaced from the ceiling and is involved in two of the earliest reflections. This screenshot shows: Blue - One mid driver gated to exclude the ceiling reflection. Brown - The ceiling reflection. Green - The ceiling and floor. This was not taken at the listening position.


All drivers have an opposite side wall reflection after 8ms. With the woofer it seems to be affecting the response only above the crossover point.

Amplfication
Midrange and treble are amplified by a DIY JLH 10W/ch class A amp.



The bass drivers are separately amped for their sensitivity using a Philips 360.

Hi there,

As Diy "buddy" group, we decided on pcm1704 without thinking about what is best in choosing a dac chip. Fortunately we found pcm1704 chip (j) on farnell.

This is first test video:

https://youtu.be/DJlK1UpE_c0

Details coming soon...

Here a new approach for an active crossover network (high pass): To get enhancement by the dynamic range in a very high quality audio system of one of my customers I have decided to introduce an active crossover network.
But the disadvantage is, that there are additional active components such operational amplifiers in the path of the signal.
But what about, if I use the ZEN topology itself as operational amplifier?
Because the ZEN isn't power source follower (it is a grounded source) I cannot use the "Sallen Key" topology. Instead of this I must use the so called "multiple feedback" topology.
But one disadvantage there is without additional operational amplifiers: a too low open loop gain. Therefore I have make a combination of both, i. e. active and passive network for the high pass.
The result is to see in the attachement. That work I have performed already 6 years ago. Now the PHL bass-midrange (Typ 1230) will be replaced by a pure midrange, again from PHL. For this reason, the crossover frequency must be increased to approximately 500 Hz and therefore I get back this single ended ZEN special amp to do this re-match. From this ZEN device I have make three photos (see below)

I would be interested to know whether there are experience with an active crossover by ZEN projects without additional operational amplifiers.

Thank you very much

I am going through a "use it or sell it!" phase! I have the major components to build Barbour's SV811-10 monoblock amps, AudioNote PT's, Electra-Print E18B SE OPT's and Transcendar chokes. I have a pair of SV811-10's and a few 6EM7 and 6EA7's. So a parts bin build seems pretty doable!

I have the Vacuum Tube Valley article covering the later revisions, but would like to read the original Glass Audio articles. (Glass Audio Volume 8, Number 3 (1996) and Volume 9, Number 5 (1997)) Anyone have access to those articles that they could share? I would really like to read the foundational work.

There was a thread a couple of years ago about a build and another person starting a build, but no follow-ups noting completion. I had an audio buddy in the San Francisco Bay Area build out the amps with the OBT-2 OPT's and military PT's. Sadly, he has passed. We both had Electro Voice Senty IVA horn speakers. (I still do, with major reworks!) I recall that I was really impressed with the Barbour amps when I heard them. Not quite the mid range of a 300B, but much better bass and dynamics.

Cheers,
Geary

Hi.

Anyone got any of these they are happy to sell?

I'm in Guildford, Surrey, UK.

Thank you, David

Hi diyA Folks

Can anyone shed light on this transformer? It's been in my parts bin for nearly 40 years and I seem to recall it was my father's before that. I'm wondering:

Is it an "auto transformer"?
What could it have been removed from?
Is it of use for tube (or other) audio?
How does one generally wire it up / use it (Australia = 240 line voltage)

Thanks for anything you can add ...
Simon

These measurements were taken at an output voltage of ~2.8V, 1000 Hz sine wave, no load.

The first in REW on my laptop through the internal sound card. The second is my Tektronix 2012. Neither are ideal, I know, but I don't think that affects what I'm seeing.

On the computer, there is a strong second harmonic (setting the THD), and the third+ are buried in the noise.

On the scope, the third harmonic is dominant, just 10 dB lower than the fundamental, while the second is half as high.

I understand the noise, and the lack of resolution, and all of that, but shouldn't the overall picture be more or less the same? These readings were taken simultaneously off the same output

Book "Beyond The Dial", Leonard Lander, has a passage of interest in this community.

This came up in connection with "Spiricom", a device to talk with the dead. I don't think all the facts presented are valid in our world, but maybe in the Beyond they are.

I have x3 Crown CTs8200 and one of them, often switches on/off.
I gather this must be to do with a relay switching to protect the amplifier.
Its not cross-wired each amp drives its own surround speaker.

So question for who knows more about this is what do you reckon/think is causing the amp to switching on/off.

I have pulled the amp cards out for visual inspection that appear fine? It doesn't appear to be overheated and most time the amplifier is running well under the maximum power rating often idle and still now and then switches off then back on again.

So it is an easy repair to maybe replace few certain components I just need to know which ones with some visual pictures so I can see where and what I need to replace.
Thank you.

This is my new design of a level after amplifier.
It adopted VISHAY company produces the IRFP240 MOSFET. Each track six only.

This is a focus on low distortion of amplifiers, circuit structure asymmetrical sent fraction circuit. And must complementary structure.

After several times of modification and test. Main improvement is the reliability problems.

Now output can achieve + 65 V sine wave and good work.

Hi all,

Very glad to join the group have been an avid sound junkie since i got some SEAS Lotus speakers for my car about 15 years back.

I have recently acquired some Sansui gear from what i believe to be the 80s (Amplifier is 2x145 watt). If you want more info on the gear happy to share, but i am keen to build a pair of speaker to go with it.

Naturally i am choosing SEAS drivers, and the plan is to use:
Tweeter Seas Prestige H1499-06 27TBCD/GB-DXT (Tweeter Seas Prestige H1499-06 27TBCD/GB-DXT - Fidelity Components Shop)
Woofer Seas Prestige H1659-08 U22REX/P-SL (Woofer Seas Prestige H1659-08 U22REX/P-SL - Fidelity Components Shop)

I believe someone highly revered in this forum has used these components together, so glad to have made this marriage.

Being an abosulte noob on the speaker build side (i have fitted speaker system into my car, but had the pre-fab Crossover), dont really know where to start on the crossover. I noticed that in Gerhard's Arkadia build he used a 2600hz crossover frequency which i guess is a great place to start, but if anyone has any resources to help with with polarty and where to start on an actual cross build i would be ever so grateful.

Further to that, being in north america, does nayone have a best supplier to but these drivers from. I have so far seen Audiohobby.eu as a great supplier but open to other options based out of North America.

Thanks for your time, i look forward to sharing!

Bram from Claagry Alberta

Hi all

Brand new here, as a registered member at least. I'm hoping someone may be able to shine a light over my recent trouble with a Rotel RB-970BX.

I was working on the amp due to one channel having high DC on its output. The amp employs a differential input stage formed of two opposing LTP's, and is DC coupled from there to the output, including the feedback line back to the LTP's.

So I set about taking my measurements on the faulty channel and found some odd looking voltages (more odd than expected) and realised that this particular point being probed seemed to get the heat sinks warm.... So maybe an RF oscillation or something being introduced with the probe I thought.

For reference moved over to the healthy channel and measured the equivalent node and within 2 seconds the two DC fuses, 4 power trannies and one driver all went open/short. So I am now baffled as I don't see the measurement points as being that sensitive to cause anything beyond a further degree of offset at the output.

I have just checked the input impedance on the old meter I was using (currently travelling) and it is low at 1M, but I'm still not sure if this could be enough to pull the amp that far out of whack.... The failure moment is a bit of a blur but I'm fairly certain the problem point was measuring the voltage on one of the LTP's "tails" with reference to ground (or at least the amplifiers reference point to zero).

If anyone has any thoughts on what may have happened so I don't get a repeat I'd me most grateful as then I can go back to warm cosey tube land!!

Ta for reading!
Dave

I recently came across this 2001 thread "Replaycing an old transistor" regarding the replacement of output devices for the Technics SE-A3 amp, which Matsushita has long ago discontinued. Has anyone made headway and successfuly completed such repairs since the last post. I am trying to figure out the most effiecient progress. What was the best transistor choice? What was the most critical aspect of the repair. thanks dan

Anyone have recommendations on books for loudspeaker driver tech?
Olson and Beranek are classic but a bit old (haven't read the updated Beranek yet)
Geddes doesn't cover my area of interest, optimisation of voice coil, pole pieces, B/H circuit etc.
John Eargle's book is the closest to what I want but seems to have some errors and lacks depth.
IIRC there was a text in Deutsch but I don't remember the title..?

Hopefully
David

Hafler DH-220 Power Mosfet Amplifier - Very nice condition For Sale - Canuck Audio Mart

Asking price is in $Can so even cheaper for you guys in the US, shipping cost however will be higher than within Canada…

SB

My woo audio wa 2 is not a good match for low impedance headphones, so I thought that increasing the coupling cap might able to give me more LF for headphones like Audeze LCD2! and AKG K702 which 62ohm!

But I also have high impedance headphones HD650/HD800s, and ATH-R70X(470ohm)!

To use all kind of High End HP with different impedance Is it a good idea to use a Toggle Switch for specific Headphones?

right now I have few caps to try 330uf to 480uf( 100v to 250v).

I have a friend for whom weight is critical in terms of lifting. This led me to question the total weight of many tube amps. There are ways of cutting down weight like SMPS supplies, but one thing that interests me is ABS boxes. We are all familiar with the useful range of smaller ABS boxes but I don't remember anything larger until I came across these 1U, 2U and 3U ABS chassis available in black or grey. Very cheap too!

https://cpc.farnell.com/pro-power/g17082ubk/case-19-abs-2u-black-anti-static/dp/EN85543

My idea would be to add a 2mm SAA anodised aluminium top plate which would earth the components connected to it. I question, though, whether anodising would affect earthing, in which case a plain or "mill" aluminium top plate would be better. An anodised front plate could be added for looks.

This ABS chassis looks like a quick and cheap way of making a tube amp.

Thoughts?

Hi,

they're out of stock. Anybody selling these?
in EU

Does anyone here know why we settled on 6.3 V of all things? -Why not 6.0, or 3.1416 V? Some of the other higher "unusual" voltages I can almost understand, being more relating to current than voltage for series strung filament applications ("All American 5" design, Muntz TV receivers etc). But the unusual, seemingly random 6.3V seems an odd choice.

There has just got to be a good story behind this one...?

I used vintage, ex-Soviet Silver Mica capacitors (dipped type) to bypass the cathode in a RIAA circuit (EAR clone). Measured stated capacitance and shows up pretty accurate in my ESR meter. They are in parallel with an electrolytic and an axial polycarbonate film.

After adding them, I noticed some strange interference in both channels.
I investigated the effect by gently touching the cap with my finger. The interference increased.
Same thing happening when a mobile phone comes near it.

The interference is more severe in the right channel, so one cap must be more sensitive.

Before adding the Micas, I wasn't picking up interference.
At least not anything obvious.

Are Silver Mica more sensitive to picking up interference?
Do they go bad with time?
Also, do they have a construction requiring one side tied to ground, for better shielding?

First time tube enthusiast, always been fascinated by tube technology and looking to dip my toes in for pennies by getting some affordable Chinese copies. Came across this 100 dollar pre-amp that's advertised as based on the McIntosh 2200 (questionable) and uses 6H3n tubes. Any information on what it really is and what to expect would be highly appreciated.

So there are a few threads here where people ask about stacking quad 63s - and as far as I can see, pretty much all of these threads die away after a few comments. Typically people comment to say how it might not work because of the delay line/point source thing, about how you place one speaker behind another at right angles, or to take the panels out and connect them all up together in a new frame.

Well folks, after nobody that I could find ever reporting on how it sounds, I want to report that I think it sounds wonderful!

Simply hooked up in parallel, both speakers at the same height (I prefer mine about a foot off the floor), with both speakers slightly angled so that they both point towards the listening chair. Impedance is halved, so a nominal 4 ohm capable amp is needed. It gives much better heft and impact, although as you'd expect it doesn't go lower. No smearing or soundstage problems that I could detect. In short if you have 2 pairs, and you have the amp, then there is nothing to lose to try this out - well bar the room that they take up!!

This probably works better in larger rooms, with both sets pulled out a bit from the back wall etc etc. Setup and angling makes a big difference, so do not neglect that.

Hello, my name is Adrien and I live in Marseille, France.
I have a sound system that includes a Yamaha receiver and Canton speakers. I'm getting a little deafer and got myself some earbuds so my wife can have the tv turned down as low as she wants and I can listen to music through the earphones via bluetooth, which I can turn up as loud as I want.

I considered spending some money to upgrade my speakers and receiver. After that, I stumbled across you and decided to build my own speakers. It appears to be somewhat complicated, but there are nice tutorials available, and I've ordered some books from the USA.

Apart from that, I am also a fan of old audio systems. I got an old jukebox that I'm trying to renovate with the help of some resources found here and there.

See you

Hope it is OK to ask this here in "Full Range" since to the best of my knowledge, the "WAW Institutional Knowledge" lives here in "Full Range"

I'm interested in setting up a WAW-type of arrangement in my Jeep - using Fountek FR59EXE 2" fullrange drivers in small sealed pods, facing the listener, on top of the dashbord and 6" KW-1 Morels down in the "knee-facing" location [I know that the knee facing location is far from ideal, but it's what I have to work with, which is why I'd like to extend the smaller drivers, above, as low in XO, as I safely can)

Fountek FR59EXE - 2.5" Full-range

I want to use __passive 6 dB series-configured__ crossovers and will be running 45WPC, Class D.

I am "set" on using passive series-configured XO-s -- I have enough going on in other parts of this project that I don't want to get into line level crossovers and extra amplification channels.

My goal here is sound quality and not max dB though I would like to be able to not have to curtail enthusiasm in turning it up, within reason (I don't need way loud, been there, done that with a Hafler 500 in my teens, trying to generally preserve the hearing that I have left).

The back of the FR59EXE are marked "15w" though some other data shows "10w" power handling. I assume that is in somewhere near full-range frequency spectrum.

My question is "how low can I go" in __crossover frequency__ at 45WPC, with the 6 dB series crossovers, at sane but satisfying listening levels, without being at high risk of either thermal damage or over-excursion damage to the FR59EXE 2" drivers?

I expect that my answer lies somewhere in the power distribution within music at the various frequencies, and partly in the fact that even a 6 dB crossover is actually starting to throttle off power throughput to the HF driver _above_ the nominal XO frequency, but I am not grokking it all fully-enough to really get where that gets me in the "how low can I go" answer for XO Hz.

Thanks very much in advance!

Hi, I have been looking around on the net for LU1014D to buy for a future little sweet and simple headphone amp, both eBay and AliExpress have a plenty of these, but virtually all of them have several minuscule details deviating from the original Lovoltech part.
I have been only able to verify with the technical drawing as seen in the Lovoltech datasheet, but it is my, perhaps limited, experience that known brand manufacturer never skimp on the package details, so the device ought to look quite exactly like the one in the technical drawing, see attached picture.

If anyone have a picture of these devices bought from a known source such as DigiKey, Farnell, Mouser etc., or directly acquired these devices from Lovoltech, please post a picture, preferably front + back + side + top view, thank you very much! 🙂

ps. Suggestions on other comparable devices I could replace the LU1014D with?

Hi,

Can anyone advise on alternatives for Nichicon LQ(M) 10000uf 63v.
I need 4no. to repair the power supply in my M&K sub. I don’t have test gear but assume it’s the caps as they are bulging… the sub was ok at low volume but started ‘hammering’ as the volume was increased.


Many thanks 🙏

Some ages ago I built the Elektor current dumping amplifier. It was a good amplifier, I liked it!

Last month I decided to revisit that circuit and after some research and several simulations I got to this improved circuit.

It has a class A stage followed by a class B and class C dumpers. And of course the famous Quad 405 bridge RLC network.

Now I have to order the PCBs and build the thing.

Mark Jordan

Hy,
I`m building pcb that will add usb and bluetooth to bmw e39 stock radio.
Pcb is made of arduino nano, pair of dip8 and pair of dip 16 ics, two linear voltage regulators DAC decoder board and few electrolytic capacitors / resistors.

Is there anything I should apply to protect the pcb? against moisture , vibrations and other shocks? It will get placed inside the radio above the main board (where tape player was).
There is nothing visible on main board from radio and that got me thinking if I need to use anything at all.

Looking for purifi modules , used or not. If someone wants to sell please let me know!
I am located in EU.

This is the famous Denon DL103 cartridge, to which they change the weak original plastic casing (one of the complaints of the users is that they do not allow a firm fit) for a solid and beautiful metal casing (anodized aluminum) and wood to choose .
All of which will make you enter a musical nirvana never imagined according to what the manufacturer promises.

The cost of the Denon cartridge is U$S 400 and the retail price of the Nitro 3200 U$S.

So does this fall into the category of the thread title ? 😀

Clear Anodized Aluminum Nitro 1 - Nitro Series Cartridges - Audio MusiKraft

Looking for a small and inexpensive amp for a desktop setup. Doesn't have to be micro-sized, but certainly not a full chassis -- think Rega Brio (which I would consider, though it certainly would stretch the budget.)

Speakers are not especially efficient so your 8wpc SET project probably won't work, but I imagine anything 20wpc or greater should be OK.

Thanks.

Hello,

I've got this posted on the Dynaco tube forum but am also posting here to cast a wider net. This is about my M-125 monoblock build (tubes4hifi).

I am looking for some debugging advice to help me narrow down something that has been bothering me. My right monoblock is not as loud as my left one. I've been using the gain on my sp14 to compensate (about 4 clicks), but I want to figure out why it is softer. My conclusions so far:
- it's not just room acoustics - at low volume listening a foot from the speakers the right output is obviously softer
- it is not the speaker or speaker cable - I swapped them and it follows the monoblock
- it's not the input - I switched the rca cables
- it is not the output tubes - swapped all 4 KT-88s between monoblocks
- it is not the driver tubes - swapped them
- voltages at all 8 pins on the 4 output tubes are all within published range.

I don't hear any audio artifacts. They both sound great to my ears, it is only a volume difference. But I want to isolate what is different and am asking for advice on how to do that. Are there measurements I should be taking at the speaker binding posts? Could a bad soldering job there cause this? Could it be a wrong/bad component on the board?

Thank you

Hi,
Not sure if this is the right place as i am new to this forum, i have just completed build of whammy by hardwiring, and when hooked up with phones, sound is flat, low volume, muddy and just nor what it should be. Phones are Hifiman 400i, which can be driven reasonable well with another, less powerful headphone amp i have



Obviously there is a problem somewhere.


The signal is coming through ok, and the background is absolutely dead quite, so earthing would not appear to be the problem.


I have checked the wiring many times, re-soldered all joints, replaced the opamp and mosfets (and put on separate board).
The power supply seems ok, +17v and -17v (leds), and on no load the will sit for hours without any heat, when i connect the circuit the voltage regulators will heat up slowly until sinks are very hot (too hot in my opinion), yet the mosfets are barley warm.


I have built a number of tube amps in the past without problem, but frustrated i cant seem to find the problem with this.


Any help would be greatly appreciated.


Thanks

Some years ago I got some pieces of ICE power modules from a german car audio guy, who closed business by last time sale.

I remember that they do not offer modules to end customers and people like me with small demand, so I did not do any further designs with them.

Recently I recognized some modules named ICE125ASX2 from several suppliers on Aliexpress. Anybody knows about them?

Are these copies?

Hi everyone. I know the title is little bit confusing but i really want to know if there's a difference. I ordered some MJW21193/94 from a reputed parts supplier & they send me two each of different package. I mean to-264 for PNP & to-247 for NPN. According to datasheet they have similar thermal properties but in the mjl21193 datasheet there is no mention of junction to ambient thermal resistant like mjw package. Physically MJL package is significantly bigger. sorry for this dumb question.

I've been looking at some horn options for 600 Hz and up.

Either using a Faital HF146 or a small wide band like the Scan-Speak 10F or Kartesian Wib70_vPA.

For the Faital HF146 I've been looking at some measurements in B&C ME90 and 18Sound XR1464C found here: [Messung] Die grosse 1,4" Messorgie - DCX464/BMS4594/NSD4015N/HF146 @ XT1464/XR1464C/PH-305/ME90/J.Sound/China - Lautsprecherforum.eu

Both of these look fine down to 600 Hz distortion wise.
ME90 gives a flatter response, and the XR1464C has better polars.
Both of these horns are about as large as I can go with regards to WAF 😀

So either I go for a flatter response or better polars..

For the wide band drivers I would probably need to go with a 2 inch exit horn.
Although I expect there would be some cancellation issues without any phase plug.

hey guys

i got this unit a few days ago and it seems that nothing can be found online! anyone know anything about this unit? or better - anyone got the schematics?

all the pots are alps blue and it seems in pretty good shape.. beside the balance pot - it is unbalanced! when centered, the left channel bairly puts out anything - both channel are balanced only when the pot is turned almost all the way to the right. i hope a simple clean up will solve this but im bracing for worst because most likely the problem is on the board itself.

other then that, a 220 transformer will be great (its 110 right now).

it does sound great!

here are some pics:
https://picasaweb.google.com/111109714414066634160/Pre?authuser=0&feat=directlink

thank you all for your time and help!
Tank out.

Hi folks,

I have a Thomann the box 350w powered cabinet the box PA 502 A – Thomann UK that has recently developed a very nasty hum (after having returned from a repair shop that cannot fix it).

The hum is so loud that if I turn the volume to even the first notch it feels like the speaker might blow!

If no XLR cable is plugged in then the hum disappears, and if I plug-in an XLR to minijack cable (which probably has no grounding), there is also no hum. But if I use other XLR cables, the hum returns immediately, even if they are not plugged in.

Any ideas what this is and how to fix it?

Many thanks!

Good Evening. I was wondering if going up the Mark Audio line is worth it? I have had the Mark Audio’s CHN 50’s for over a year and I have had some time with them under my belt. I’m a huge fostex guy and I noticed strengths and weaknesses of the Mark Audio CHN 50’s drivers. Yes its only a 3 inch driver and it’s a great bang for the buck driver. So is going up the line worth it in the following questions?

1. Cost vs sound
2. Cone material
3. Design

I just don’t want to build and waste my time if it’s not worth the investment on moving up the mark Audio line. Please let know what you all think? Thanks JM

I'm repackaging my old turret-board Transcendent Grounded Grid and want to delay the HV to allow the tube warm-up and keep the output muted until HV is up.

It has two hv supplies: +200VDC and -200VDC. Those and the heater supply are all fed by their own secondaries from a single transformer. So if I delay HV, it has to be done on the secondary.

I have 4 channel relay board connected to an Arduino. The relays are rated for 10A 250VAC.

ANMBEST 2PCS 4 Channel 5V Relay Module with Optocoupler High or Low Level Trigger Expansion Board for Raspberry Pi Arduino

relay 1: Secondary 1 to NO - COM to +200VDC PSU
relay 2: Secondary 2 to NO - COM to -200VDC PSU
relay 3: Signal Output 1 NC - COM to ground
relay 4: Signal Output 1 NC - COM to ground

Relays 1 and 2 come on at 30 sec, relays 3 and 4 at 40 sec. I have a basic sketch that seems to work.


Am I missing anything?

Hi,

I have a Velleman pcsgu250 dual channel USB device. I haven’t seen updates now for a few years.

I use it now only as a signal generator, as I use other software with a high end DAC to make measurements. The spectrum analyzer software from Velleman is not exactly state of the art. Guess it never was either…

There is a SDK for this device too, so I wonder if there is any alternative analyzing software available for this device. So far Google hasn’t found anything.

Regards, Gerrit

After a long while recovering from a fractured humerus at last I dusted up the soldering gun, and was able to put something together that surprisingly for me works quite well.

Attached the schematic and build. The point to point layout is a mess, I have never been a tidy builder, and is "great" to see things have not improved a lot in that area 😱

I get around 13.5V RMS on 8ohm before the distortion appears on the FFT, visually the signal looks and sounds quite good at up to 15V RMS. After that the first stage start drawing current (me guessing) from the LTP. The UL curves for a 5881 with Zp-p 6600 ohm and B+ 400V show a peak power around 29W so it seems to match quite well. 100 Hz hum is very quiet on my speakers (90db), need to go close to the speaker with volume pot to the maximum to hear it.

Things I'm thinking about before I build the second channel:
Adding the screen limiting resistors. Do we still need them for UL?
Adding a soft start to HV, it makes a relatively loud crack on the speaker when I turn it on (sign of something very wrong?)
CCS on the LTP. Does it improve things a lot?
Add a bigger capacitor to the power supply.

Any suggestions/criticism is very welcome.

I'd also like to thank the people in the forum for their very useful advice, especially (original thread: "Newbie looking for advice on stereo amp layout"):

@Eli Duttman for suggesting the Eico 89 as a fool proof starting point. Spot on!
@HighVoltageHit for layout recommendations and encouragement
@Tim Bavus for suggesting chassis reinforcement.

Regards,

Jose

Hi,


I have some older TO3 transistors that I am not going to use anymore so if anyone is interested, I can ship them anywhere in Europe for the price of postage. Shipping from Austria.



They are

130x Tesla KD605, NPN, 70W/40V/10A
50x Tesla KD615, PNP, 70W/40V/10A
50x Tesla KD366, Darlington PNP, 60W/60V/8A.

Current line stage employs one 5842 RF triode p/c > Magnequest "DS 050/600” OPT w/5K primary/600R secondary, three secondary outputs provide various gain/impedance.

I loved my preamp till a friend let me borrow his $6k commercial preamp with two each 12AU7 and 6SN7 (no output trans.) Conversely my 5842 outperformed a commercial 300B line stage and ditto another 6SN7 line stage. British Icon's LA5 TX employs one 6SN7 p/c > proprietary output trans.

I respectfully request schematics for the highest performing tube line stages, including circuits suitable for the above described output transformers.

Tx!

Hi,
I have come across a couple of these speakers, TC14SG29-08, from a old center channel. I'm looking to make a pair of bookshelf speakers out of them but don't have a datasheet. Does anyone have a datasheet? Could I possibly use the datasheet for Vifa TC14SG49-08, visually the only difference seems to be the truncated mounting frame.


Cheers,
Neug

I just listed these on eBay. If anyone is interested please read the description and shop with confidence. I list them to sell, not for profit.

The drivers are in excellent working condition and will ship from Canada.
Eton 26HD3 1" magnesium dome hi-end tweeters - PAIR | eBay

Hi,


I have 11x LM3886T and 14xLM3886TF. 5 Euro/piece plus postage or free pickup. Selling all of them together or all of the T together and all of the TF together. Bought from Mouser. Sending from Upper Austria (Europe).

Hello,

Need the power, ground and remote connector for the Audio Art 260.6XE.

Outside the amp:


Inside the amp:


Thanks for your help.

Hello, i have some questions.
Can i solder mosfet power amp and make it work with the avt50 instead of tda chip? Mosfet power amp from Marshall lead 100 mosfet.

Aesthetically the max size subs I can afford are about the size of Marty Cubes.

Price wise for passive cabinets my price for the 2 subs is ~$1,200, before amplification.

Other considerations;

Room size is about 3,400 cu. ft. (sorry, meant cubic feet not square feet)

My mains include 2 OB Servo subs which are good for music to about 20hz and HT SFX ~25-30hz.

Main freq range for new subs is up to 50hz.

My current consideration is Ultimax 18" in either a Marty Cube or sealed cabinet.

I will use some form of equalization. Currently have Crown XTI 2002 (built in EQ) driving a pair of down firing Dayton 10" Titanics in sealed enclosures.

So with the limiting factors of size & price and a focus on rather low frequencies, what is my best choice for a pair of Passive HT subs?

I am not opposed to other designs, like dual opposed 15s, or anything else which will maximize my low frequencies with decent SQ. As Mae West used to say, "Too much of a good thing (bass) is never enough."

HI folks, This is a reverse polarity damage ,
All the fuses on one side (f100-f107) are blown
Fet's seems to have survived ,
there is some exploded caps but prob from before this reverse polarity accident happen.
Board is covered in some form of liquid,
There is no shorts between the positive and negative terminals.
Might have a good outcome, ( well replacing them fuses is a big job 🙂 )

Any pointers, etc, you guys have a eye for this stuff, i'm merely a beginner.

will keep updated and will fallow instructions if any are given.
Many thanx.

I have tweaked my speakers to where they don't do anything specifically wrong I can tell, but they sound a little distant. Mostly listening to classical guitar. Good, but not quite right.

Any suggestions what I am missing? The room is pretty bright, so I do have a pretty gentle slope from 4K to 20K of about 3 dB dialed in. If brighter than that, then trumpets or Joni Mitchel get harsh. My wife still thinks a flute (Poem) is a bit bright.

System is based on Seas ER18 and 27TBFC/g tweeter. My crossover is around 2K, second electrical. Might be still a shade low for the tweeter, but the phase is pretty good through the crossover region and I don't play very loud. I do run a 12 inch low Q sub but that is not really in the equation.

Something new? Something used?

Any good kits/modules I should consider?

thanks in advance.
bob

Any leads on a repair/service manual, NOT users or owners manual for a Bowers & Wilkins DM605 S2 plate amp would be greatly appreciated.

Thanks,
Jeff