I'm testing some line level center tapped transformers today for how evenly they phase split a signal. I've never done this before so maybe someone can explain what I'm seeing. I'm using this transformer:

EDCOR - XSM Series

10k to 10k

I hooked the function generator to the primary and set the level to 1 volt. I hooked two channels of the scope to the split secondary so the scope shows the split signal very cleanly in perfect antiphase. Leaving the level the same I try out different frequencies. 1K, 5K, 10K, 15K, 20K...

Here is my question. As I stay below 15K the amplitude of the two phases is pretty much equal within 1%. But as I move above 15K to 20K one of the phases grows in amplitude over the other phase by a greater percentage.

Is this caused by the fact that the transformer is reaching its rated frequency limit? Or is it caused by the fact that a higher frequency is exposing maybe that 1 turn difference between the secondary halves? Or is it caused by core behavior at the higher frequency?

In any case the antiphase remains perfect, its just that at higher frequencies one side of the secondary grows noticeably taller on the scope.

Using this as a PP phase splitter would cause an imbalance at higher frequencies? There is not much musical content above 15K. Am I being too picky? I was expecting to see both phases stay identical in amplitude as frequency increases.

The Edcor transformer above is actually much better than some others I tested today. But they all exhibit this rising frequency brings on amplitude imbalance behavior. In fact one cheap radio replacement transformer I have started to show this imbalance as I approached 8K to 10K! This one (its a stepper-upper so maybe that makes it even more difficult to keep balance).

https://www.tubesandmore.com/products/transformer-audio-interstage-10-ma

Do you suspect a step-down splitter would probably not exhibit this behavior as much? I have not gotten to testing a few of those yet. I suspect they will maintain balance better just on a hunch, if so I'd probably want to use the
at as a PP phase splitter instead, then get back the gain in the driver.

OK I just tested the Edcor 10K to 600R. It exhibits the same behavior but not as bad, I start to see it begin at 13K but the percentage difference between the phases in amplitude is not nearly as far off as a step up or a 1:1 transformer.

Hello friends.

After a long time without posting due to work and other problems I bring a new amplifier that is still being developed and tested.

The PS80 darlington series is a small amplifier with darlington transistors at the output for a very simple purpose: to push my bass.

Simulator tests (the circuit is not yet definitive) have shown excellent performance at high frequencies as well, but I will use it to push my bass speakers.

I will still manufacture the pcb, 'tune' the amplifier and after that do the test using a QA401 audio analyzer, from QuantAsylum to better see the behavior of THD, IMD and the like.

Here in Brazil as always very hot and with good music !!! Hugs
(Paulo from PHS Audio)


Follows the provisional and still pending adjustment of values

View attachment PS80-NOVO-OPEN.pdf

I have searched, and found to no avail, anyone who has used the Scanspeak 10F/8424G00 as a full range? or possibly with a helper tweeter.

I have only really found these threads, but no actual listening opinions.
http://www.diyaudio.com/forums/full...-driver-scan-speak-discovery-10f-4424g00.html
HTGuide Forum - Low Budget Speaker Porn
As a mid range, and not full-range-
http://www.diyaudio.com/forums/multi-way/193689-build-thread-ardor-point-source-monitor.html

I have been looking into some mini monitors for a specific application-
http://www.diyaudio.com/forums/multi-way/193917-4-mini-monitor.html
And a previous thread with my impressions of other Full Range drivers-
http://www.diyaudio.com/forums/full-range/190888-replacment-veravox-5s.html
More recent (enough output) from a sealed BB3.AL-
http://www.diyaudio.com/forums/full-range/188987-hobby-hifi-bb3tl.html

And its been suggested that a full-range driver might suit me better.

This is for low level listening, in a small 8ft square room. SPL Output/bass depth is not an issue.

Thanks, Rob

Hi,

I have some radio gear that needs 13.8 VDC running off two linear PSUs. I understand if the voltage regulation fails then a higher voltage can appear at the outputs and burn up whatever is attached to the PSU.

I haven't been able to find a clear presentation of a crowbar circuit that shows how to calculate the component values for practical applications.

What are my options for building a black box than can go between the PSU and each radio?

If my question is too open-ended it is because I have been away from electronics for a long time and am getting back into it recently.

Thanks!

For Sale a a pair of the RTP3 Platine Tube preamp for sale. High quality pcb with for documentation (Schematics, detailled BOM, interconnect, etc). With these you can build the actual VSE RTP3 tube preamp, one pcb per channel. Each pcb contains everything for one channel, all power supplies, including the HV Shunt regulator, just connect the power transformers.

Very good preamp, probably one of the 10 top tube preamp, and one of the best for me, I have one. These pcb make building the preamp much easier. These pcb were a special order for one member but he changed his mind.

To complete the preamp you'll need the input source selector, and volume control. Take not ethat this preamp is full balanced, and that the original design was using one stereo source selector and one stereo volume step attenuator per channel.

If interested send me a private email.
SB

The term came up and someone was posting information that I found questionable.

Terms used to describe the intensity of the vacuous space within a vacuum tube’s glass envelope. A hard vacuum denotes a more complete vacuum is created in the tube manufacturing process. Hard vacuum tubes – like the 6L6 and 6550 – have a higher saturation threshold and therefore distort less easily then soft vacuum tubes. Soft vacuum tubes – such as the EL34 or 6CA7 – have a less intense vacuum (sometimes called a gassy vacuum), saturate more easily and therefore break up [distort] more quickly. - Sweetwater

Click to expand...

"The tube "hardness" or "softness" - as you justifiably name itDijimiWrey - is narrowly associated with the degree of vacuum in the tube itself.

Tight vacuum tubes sound "harder" when clipped, have more headroom and attack, less compression, can afford more plate dissipation, and last longer because they hold their tolerance tighter over time. This is often the prerogative of military or industrial tubes if they have been suitably stored over time.

Soft vacuum tubes sound "softer" when clipped, less headroom and beefy punch, more compression and sensivity, but they widhstand less plate dissipation (beware red plating) and have a shorter life duration because their tolerances degrade faster over time.

In the early days of Radio, it was well-known that lower vacuum tubes were better for receiver detection stages (where more sensivity was needed) and higher vacuum tubes were prefered for RF amplification stage (where gain stability was required)."

Click to expand...

First time I heard about soft and hard tubes. I looked it up and it sounded questionable to me.

I remember reading an Aspen Pittman article on how the vacuum within the output tube = degree of distortion. And thus the myth began...

Click to expand...

So I am questioning the most knowledgeable bunch of tube geeks (if I may say so) that I know of. So is the concept true? Or is it somehow mistaking tube geometry somehow? Inquiring minds, you know how it goes.

Hello

I have a Behringer NX600D amp that runs two DIY VBSS 18" subs.
I have heard of the possible benefits for having the subs connected to the high level inputs (especially if focusing on 2 channel audio, which I am) and thus I wanted to give it a try.

Anyways I was hoping to get some advice on wiring and what I was thinking is:
Receiver --> A level / speaker outputs --> Speakers
Receiver --> B level / speaker outputs --> Behringer --> Subs

Question #1
The speaker outputs from the receiver had to be converted to an XLR input for the Behringer and thus I wired the positive to the positive xlr pin and the negative to the negative xlr pin and have nothing connected to the ground pin. Is that the proper way to do it? Or should one bridge the negative and the ground?

Question #2
The main issue that I am having is that the high level outputs are L and R and the inputs on the Behringer are also only L and R and there is no obvious way to combine the signal.
Thus sub #1 gets only the L signal and sub #2 only gets the R signal.

This is probably not too big of a deal, but it would be nice if the L&R signal could go to each sub.

So I was wondering should I just bridge the positive and negative B level outputs together and then run them to the L&R inputs? Or would this have any downsides? I know that one should not bridge the outputs and run it to a speaker as the load will be different and could blow the speaker/amp, but is running a bridged signal to the Behringer amp the proper way to it?

Any advice would be much appreciated on the wiring itself and also how to get both signals to both subs.

Thanks!

Hi all,

I have recently became aware of trade-offs in loudspeaker design and couldn't find a thread about so here goes.

I've been reading here actively for past few years and somehow totally ignored/missed the importance of thinking through the trade-offs while designing a loudspeaker and I would have liked to realize it a lot sooner 🙂 I'd like this thread to help others to get the awareness early on.

A thread without content isn't very valuable so hopefully many members would share their thoughts. This is more philosophical subject than anything specific so I'm not sure if this thread leads anywhere. Anyway, here is my big insight.

There are some "main categories" of compromises in a DIY loudspeaker design project which in my view are cost, size, aesthetics, audio quality and having fun. Some decisions one have to make along a loudspeaker design process have trade-offs in more than one of these main categories. For example limiting the loudspeaker enclosure size might affect the bass extension, cost might limit options for the surface finishing and so on. I think prioritizing these main categories for a given project provides good basis for the decision making and gives confidence to successfully meet the project targets, or fail early if the project was too unrealistic. Ability to follow the set priority would define how many of the decisions, or compromises one was able to take, were actually good for the project.

Trade-offs seem to be everywhere and I find that being aware of their existence and what they are is very important for success of any project. IF one want's to make the best audio quality loudspeaker in the world, like many do, all trade-offs possible should be chosen from the cost, size and aesthetics categories and in this order. Trying to pursuit such project one should better be wealthy, have dedicated listening space and be blind which isn't fun at all so better relax from the goal a bit 😀 Now go and make the project you are involved successfully finished while having confidence on the decisions and lots of fun!

edit: I found out term "Designing from first principles" that would match what I'm trying to grasp here.

I ordered two SMPS off eBay, pictured as below. They are labeled as +/-30v, but the actual output under 10ma current load is +/-39v and +/-33v. I have emailed the seller but got no answer so far. I'd like to find a way to adjust the output voltages, maybe by changing some resistors? Any one is familiar with this particular model?

Thanks!

This NOS Dac which is causing something of a stir is getting soem very glowing reviews including in Hi Fi Critic. In all the threads and reviews I have read up to now there has never been a mention of the manufacturer or chip number that is actually used. It is often mentioned that it is not an audio but an industrial one used for other things. However it should still be easy to get the chip number and who made it ?

I mentioned this Dac to my audio repair engineer and he sent me an e-mail that they were using TDA1543 chips which I would find pretty hard to accept as these are nothing like what is being described and are just cheap replacements for TDA1541 chips.

Does anyone have one of these Dacs and have you looked at what chip is installed . Would be interested if anyone can shed any light on this.

Last time I made a guitar amp was 1975, and haven’t hardly played at all since then either. Time to get back into it! I want to make a small practice amp and I was wondering, would single ended class A be a better choice? I’m thinking of even harmonic production when you start to push it a bit. Only got a small handful of valves on hand, a 6DQ6A, two 6CA7s and a NOS 807. I’m leaning toward the 6DQ6A with about 120V on the plate. Not looking for high power output, just a setup that will ease into more “colour” as I wind the volume up. Low budget too. Any suggestions?

So I've got two amps on my desk right now that I've put together. One has a basic Sunn Model T style preamp, and one has a Marshall JCM800 style preamp. Both are push pull, although one's 4x6L6 and the other is just an ECC99.

Both amps use the phase inverter from this old ax84 document: https://ax84.com/archive/ax84.com/static/corepoweramps/20W_PP/AX84_20W_PP_Poweramp_Schematic.pdf

The preamps are of course somewhat different, but they both do have a gain stage with cathode follower right before the tone stack. Both amps have separate power supply nodes for the phase inverter tube and the gain/cf tube.

Both amps fundamentally work well, but in both amps, I'm having a problem where signal that seems to be bleeding out of the cathode follower and into the phase inverter.

It seems to be some kind of impedance node issue - from playing with various volume controls, it basically seems the higher resistance to ground there is on the preamp side of C13, the more signal bleeds in. Even if there is no connection from the output of the tone stack to the volume control, or i ground that out, the sound still bleeds through.

The bleed signal is bedroom volume loud, and very thin.

So, the signal is either bleeding through the ground, or bleeding through the power supply somehow. The grounding schemes are pretty standard, and the power supplies are standard as well, with a cap and dropping resistor for each node.

Have any of you guys seen something like that before? What would I do to solve it? I thought maybe I had made a silly mistake on the first amp, but the second amp is exhibiting the identical problem, so there has to be something design related.

hi,
recently i purchase 4 way JBL 4756 (2206,2402,2445,e155-sub)
now, i cross 8 CH with software and power the system with 8 CH amplifier.
i start to measure each speaker from 1 meter distance to find the best frequency to cross.

do i need to measure the speaker from the sweet spot (were i sit)?
or measure from 1 meter?

thanks

I need a home for my Zoudio amp and power supply.

Any ideas for items to look for on Facebook marketplace or whatever that I could use for a chassis ???

small computer case ?? Old VCR ? lol

After building the Nobrainer power amp designed by Joachim Gerhard modded according to FdW ideas JG´s Nobrainer and Nobrainer Discrete - Page 33 - diyAudio I want to build a special version using a singleton input stage and double output devices so I can have more power and also verify the differences relative to the original opamp input.

Following Bigun work I asked his permission to use his input stage TGM8 - an amplifier based on Rod Elliot P3a - diyAudio

The resulting schematic sims ok but I would like to have the experts input regarding numerous doubts I have.

For reference I am posting the LTspice file as well as an initial schematic.

6 years ago I started this thread to develop a SE IPS power amp.

Now I am presenting the final evolution, the P200 model that uses Laterals on the output and a sziklai cascoded and ccs loaded on the input.

I was wondering if anyone else had experienced an issue with a Rotel Rb 1080 where 1 channel cut out I know they have 5 fuses but dont have the expertise to pull it apart to check them

Hello all,
I have a pair of Kef 104/2 speakers that I have owned for 32 years.
They have been very well loved and taken care of, however, recently I am noticing some distortion, unwanted noise, coming from the lower midrange on one speaker.
Visually both mid range are pristine.
The foam donut on the lower woofer is "tattered", and I see I can easily fix that;
but I doubt that would cause a problem with the lower mid range?
Any suggestions?
I'm sure it's time to replace the capacitors, could this be the problem?
Thanks for your ideas in advance, Dan.

Hello,

I'm looking for inexpensive dac. Found this
SA9027 ES9023 24bit 96kHz Asynchronous USB DAC HiFi Sound Decoder with Case | eBay
And DA3 SA9227 PCM5102A 32bit 384kHz USB DAC HiFi Asynchronous Decoder Case | eBay

They look like same but only dac chip is diferent. which one is better?

Another option is to make AMB "gamma2" dac and feed i2s with something like whis: WL High End CM6631A 7 Pin USB Daughter Card Free Shipping 1504A | eBay instead of 60$ AMB "asynchronous USB-I²S module".

+use external power supply.

Any advice?
Thank you

(Image of prototype)

The EC7293 uses 2 chip amps in parallel for high power with a discrete error correction frontend which reduces distortion; and has very low memory distortion. High sensitivity makes it perfect for a variety of sources with 8ohm and 4ohm speakers.

Input impedance: 27k
Gain: 32db
Distortion 1K; 8ohm; full power w/Antek AS-3225: <0.0005%
A short review.

At 8ohms:


At 4ohms:




Board size: 6.25x2.25"

*****There is not a mirrored left/right set because it would screw up the feedback layout*****

Discrete front end: 4 transistors

PVI: The frontend uses a photovoltaic power supply for galvanic isolation of the signal path. It uses a G4 LED bulb with a current source to disable the onboard driver of the G4.

Distortion: <0.0005%

High power: These are running in "modular" mode so that they can handle a 4 ohm load with some dips, while providing substantial power with a max output current of 20A. The Antek AS-3225 is a great fit for 60/120w. More power may be possible if you follow the guidelines of the TDA7293 datasheet and make provisions with higher voltage capacitors, and larger heatsinks.

Terminals: Happy to say we've found some that are based on a copper metallurgy, that accept decent sized wire, and don't strip too easily (I can torque them pretty good with screwdriver) that the boards are made to fit, and I recommend in the BOM.

Input Capacitor: This one is less sensitive to capacitors compared to the DIY7297. It has provisions for the same PHE426 and other caps. There is a slot-hole next to the pads so you can zip tie on larger caps and it has extra pads on the bottom to connect off board/long input capacitors.

CFC, smart PCB layout, & Copper Pours: Trace routing is optimized to improve performance and the power capacitors are placed for field cancellation (CFC); and copper pours are used for lower inductance.




Dualpole PSU PCB

Board Size: 4.25x3"

TO220 Diodes

CFC, smart PCB layout, & Copper Pours

Via holes for snap caps

RC and bypass: dampen the transformer & reduce noise


Suggested implementation with EC7293:

• 18000uF to 24000uF per rail
• Antek AS-3225 transformer
• Keratherm insulators from DIYAudio store. (Chip tabs are 1.1” apart).
• Heatsinks need to be larger than used on the 7297, nearly any enclosure with heatsinks for sides should work
• 3U enclosure from DIYAudio store is a good fit. **
• 2x Duapole's for dual mono with 2x transformers (Antek AS-2225)

**2U may work in dual mono with two smaller (shorter) transformers

Price & Amount needed to Print:

In order to print these up so I don't run out the day after, I'd like to see 12x pairs to get this going. To anyone that liked the DIY7297, this one is better, simply better.

EC7293+G4LEDR PCB $45ea (you'll need 2, to make a stereo amp)
DualPole PSU PCB $40ea

Shipping USA $8
Shipping International $16

And it will come with a BOM and some build details.

DeeJayBump 2,2
SAinet 2,2
shacketf 2,2
myl 2,2
mctavish 2,2
Stephen S. 2,2
jameshillj 2,0
drkingweeb 2,2
HaflerDh500Fan 2,2
genjamon 2,2
angchuck 4,1

Click to expand...

Anyone here upgraded from the 12inch Ferrite to the 12in Alnico drivers? I have had a pair of the ferrites for a few years and I love them. But have had them awhile so thinking about going up a notch.
Can anyone personally attest to the difference after break in?

Hi all,
Was wondering what Keysight/Agilent/HP VEE runtime program is everyone using under Windows 10? I can only get the VEE Pro 9.33 to install and it does seem to control the HP well, but I don't have $1k for this to be able to keep it past trial. This used to be free, as far as I know, and I'm just unsure what are the current options.

Secondly, is the Agilent/HP 82357B interface - which seems to be 100% genuine - supposed to come with the VEE program on it?

And, thirdly, any issues with Pete's tools running under 9.33? The VEE itself controls the HP perfectly well, but the programs were not doing anything. Just curious on the success rate there.

Thank you!

yep - 1928. 😀

I don't have the patience to box things up, but I am setting up a new room and will be letting a lot of extra parts that I have fly to other pastures..

If there's anyone in the Mount Pleasant - Charleston area that is interested in lots of various parts, let me know.

S

Hi, a friend has c a pair of Wharfedale E30 speakers. The crossovers both have unidentifiable fried resistors. They appear large red resistors but a) no visible writing (blackened) and b) as both have failed, neither can be tested

Does anyone know the value of the resistor or have a schematic ?

many thanks

Yes you read that right! I have used a soldering iron and have recapped a few tube amps and one Magnavox console as a retirement hobby. A family member asked if I could do anything with their old console (Grants store Bradfod line).

By default, I plan on replacing all of the electrolytic caps to try and breath a bit more ghusto into this very small but suprizingly detailed sound stage of this very under powered unit.

My observation thus far:

FM pulls in quite a few stations with solid sounding signal.
tape monitor plays well with bluetooth input.

My question is predicated on the fact that the FM signal indicator light grows dim when the volume as gained up. Is there something other than Cap replacement that may need attention?

thanks for any and all input.

I am busy collecting parts to build Mr Millett's regulated tube high voltage Bench Power Supply. Link - High-voltage bench supply

Has anyone done a successful build. Any tips and tricks?

I am having problems with a NAD 1020 Preamp. The unit powers up fine and the 120V plugs in the back of the preamp also work as I can power a phono or CD.

The problem is that I get no output signal. If I turn up the volume all the way, you get some very distorted and scratchy thumps and pops that is generally coincident with the bass of the music being played.

I popped the unit open and there is nothing that looked obviously cooked.

Does anyone have any suggestions as to where the problem may be?

It does not seem to be a power supply problem. I fear that one of the transistors may be cooked in which case I doubt I would be able to track the bad one.

Any help would be appreciated.

Nearly new condition. Only used a few hours. Decided to buy rather than build my new speakers. $100 shipped or make an offer.

Eminence has introduced a monster woofer and I wanted to see how it performs.



Here's how it performs in a QB3 ported box. There's a little bit of droop on the low end due to the low qes and qts.



The NWS6021 is an interesting driver. If you put it in a conventional enclosure it's challenging to hit xmax, because the driver just has a RIDICULOUS amount of displacement. There are plenty of 12" woofers with 21mm of xmax, but a 21" is unheard of. B&C iPal is the only competition I'm aware of, and it's much more expensive.

So I made this horn by juggling the parameters to push the F3 as low as possible and no further. Basically the idea was that if the F3 was 35hz or 40hz, the Eminence NSW6021 would *never* get close to it's xmax. (This assumes a high pass filter is in the mix.)



24 cubic feet and an F3 of 22Hz. Five thousand watts of power handling. Yowza. 135dB of output.

Over at data-bass.com, the Zod Audio Maul rules the leaderboard, with four Rockford Fosgate nineteens. I think a couple of these Eminence woofers could likely beat it, for a fraction of the cost.



Here's the response before filters



Here's the excursion with and without filters. The filters are there to push the woofer right up to it's limits.



Here's the unfiltered response. This is kinda lump, admittedly, but I specifically pushed it lower than a conventional alignment so that I could use all of it's xmax. (If I'd used an F3 of 35 or 30hz, it wouldn't even get close to it's xmax.)



Here's the model

I'd like to ask for guidance on the type of phono pre-amp for a low output MM cart.

For example: Technics EPC-100c
output 1.3mv
DC resistance: 30 ohms
inductance: 33mH
impedance: 210 ohm, 1khz

This is not a typical MM cart so I wonder if it needs an unusual phono stage? Or just any good MM phono with enough gain? How much gain?

thanks!

I've been prototyping headphone amplifiers for some time now, using tubes I have on hand from TV pulls and whatnot. I currently have a more-or-less textbook 6FQ7 push-pull triode setup with a 12AT7 preamp and phase inverter. It's fed into a 10k:600 OPT and sounds good to my ear. B+ of 390v. Plate voltages and current are all in spec. I'm curious about its actual output impedance though. That OPT is almost certainly not ideal, the 600ohm secondary notwithstanding. I've attempted to learn how to figure it out, but so far it has eluded me. It'll get plenty loud for 98% of music out there, but I would appreciate a tad more headroom in case it's ever needed. I was looking online and found a good bit of praise for the 6H30. It has overall higher plate dissipation at 8W for both plates combined. The 6FQ7 is 4W each or 5.7W total. I've also read that the 6H30 has considerably lower output impedance. That being said, I have no idea what said impedance would be with two 6H30 triodes in PP. Can someone clue me in? Is it worth buying $70 worth of new tubes or should I look into a different OPT for what I currently have?

Hi all





Would you recommend and what result to expect if I use my car subwoofer CLS110RG-W7AE for home use as HiFi stereo and HT subwoofer??
I need only little help for my KEF R3 for stereo and aiming for bass quality not SPL.


It is original sealed JLAudio enclosure, I think 27 l volume but not sure



CLS110RG-W7AE - Car Audio - Subwoofer Systems - ProWedge™ - JL Audio


I was thinking on using Hypex 251 amp in separate small enclosure to drive it.
Room volume is 1525 cubic feet or 43cubic meters.





Driver specification:
Free Air Resonance (Fs)30.6

Hz Electrical “Q” (Qes) 0.578
Mechanical “Q” (Qms) 7.647
Total Speaker “Q” (Qts) 0.537
Equivalent Compliance (Vas) 1.28 cu ft / 36.1 L
One-Way Linear Excursion (Xmax)* 0.9 in / 23 mm
Reference Efficiency (no) 0.17%

Efficiency (1 W / 1 m)** 84.3 dB

SPL Effective Piston Area (Sd) 59.8 sq in / 0.0386 sq m
DC Resistance (Re)2.75 Ω


Thanks

I have a pair up for auction.

Rare Amperex Orange Label 7868 Vacuum Tubes Vintage Tested Matched Pair 82/83

Hi,
I´m looking for
- 1 pair of Dayton RS180-8S (the shielded version) or
- 2 pairs of the not shielded version RS180-8
in good technical and optical condition.

I´m located in Germany. Just offer me everything (with shipping costs), we will surely agree.

Best regards
Andreas

Several years ago I rebuilt/restored a Dynaco FM-3 with the singe board from the FM3Zone, it all looks OK, but it won't tune and only hear a faint sound. Anyone of have any interest in taking a look? I am willing to pay. I am not experienced with radio issues but have no way to tune first IF stage or determining if if other transformers are working correctly. I realize this has limited value but have already spent enough time and money and would like to see thsi through. '
Many thanks for looking

SOLD

New pair of Lii Audio F-15 drivers. These are 15" full range drivers.

$380/pair or best offer

One Pair | Recommended 15" Full Range Speaker Driver | Fast High and Scaled Sound | F-15 - Lii Audio, unique speaker, amplfier, quality and cost-saving parts for HiFi DIY

Prefer local buyer in Seattle PNW. Will consider shipping in continental USA.
No trades.

Re: Cerwin Vega CV-1800

Protection light is on in one channel. No obvious damage. The P/S seems good and the other channel works fine. This unit was returned to the CV depot twice in the past before the warranty ran out for the same reason. I found a "Goob" job of a resistor piggybacked with another resistor still in circuit for some reason. (I wasn't impressed with the quality of the "Patch" job)

Where might a guy find a repair manual? I'm very capable to do the repair but I want the biasing procedure and test point voltages..

Forgive me if this is in the wrong section. Thanks in Advance!

This is a discussion of parallel tubes.
Read at your own risk.

Attachment is Here:

Hello all, newbie here.

I am contemplating building my first stereo hifi tube amplifier. I've been reading up on (guitar) tube amplifiers, watched way too many youtube clips and have (succesfully) built two guitar amps (Marshall JTM45 and JCM800). Despite that I find it hard to get started in the hifi amp world and that is the reason for this post.

I've got lots of question, but I'll limit myself to a few. Here they are: What amp do you guys suggest I should build? Are there any informative build threads or sites? Any must read books, articles or websites? I've read both tube preamp book by Merlin Blencowe and the power amp book by Richard Kuehnel.

Any advice is welcome. Thanks in advance.

SOLD Pair Anarchy Exodus 8 ohm woofers

Pair of Anarchy Exodus mid-woofers, like new condition. I used them in an audiophile system for two years in a tapped horn. 6,5 inch mid-woofer, excellent for tapped horn sub or in an easy two way speaker, 8 ohms impedance, 125 watts power, 35- 3000 Hz, U$ 66 each new. Sell a pair for U$ 75 or 95 CAD.
I live in Canada. Will split the shipping up to 15 U$\20CAD.

Despite the look on the pictures they are black.

SOLD Pair Eminence Delta 10 A woofers

Pair of Eminence DELTA 10A woofers, like new condition. I used them in an audiophile system for two years and replaced them with some 8”, so am selling these excellent woofers. 10 inch high efficiency woofer, 8 ohms impedance, 350 watts power, 98.8 db SPL. U$90 each new. Sell a pair for U$ 100 or 120 CAD. I l'am in Canada. Will split the shipping up to 15 U$\20CAD.

I've got a drill file that I need to change one of the drills on. Currently the line in the file is

T3C.05F107S55

which is tool 3 = 0.05 inch (1.27mm)

But what is the F107S55 relating to?

The part requires hole diameter 1.91 - 1.96 mm. Is 0.076 inch a valid drill size?

Since I'm converting my Stax SRM-007tA from 6CG7 to 6S4A tubes, I'm looking for a couple of the latter (6s4a).

Quads of 6S4A would be ideal, like actual matched tubes or matching date codes.

In order to provide something nice to look at, I've attached some pics of the ongoing conversion 🙂

I’m repairing an older PPI amp .

The gain pot was coming apart from someone else’s attempted repair .

The pot still works but 1 pin is missing and the other is badly bent to keep the pot together .

Wondering what do you use in this case to put the pot back together

Hi, would anyone know which company supplies the best replacement bulbs for the meter displays on this amp?
I believe they're 14V, 0.8A 'Stanley' lamps...?

New My NAD 3020A, with no turntable connected, has a loud "hiss" when 'phono' is selected, but all the other outputs are super quiet.
Any suggestions as to what would cause this?


Also, thinking of replacing the four main power supply caps with either Panasonic FC cap, or Nichicon KW or FW.
Would appreciate advice on this choice, and is there anywhere other than the big suppliers who supply authentic caps in the UK without high delivery or minimum order prices?

How is possible to search on forum 3 letter abbreviations like DSP, AMT, IIR, FIR, HPF, LPF, Qts, Qms, ....?
Currently I get message: The following words are either very common, too long, or too short and were not included in your search.

I put the new faitalPRO 3FE25 ("mud" cermet) 3" on the ~middle of the centers I cut out of my homey style 11 cu ft Stereo subwoofers (two 12" SB woofers in one big box. The only approach no one wants to attempt is one big box... 24"x25"x31" of BB 1/2" glued by WoodTiteIII.

Seems to work. The cascading crescendos in "Pines of Rome" by Ottorini Respighi brought tears to my ancient eyeballs. I never thought I could enjoy that monster in any place I could afford to live. Damn. I was SO young. once.

I am 73 and live in a tiny one bedroom apartment with my wife. We have two big windows, facing north. In Texas, that is the only way to survive "Texas weather". Snowstorms and hurricanes. Not on the same day, as a fool's rule.

Sound great through 5 each 1/2" holes that allow the drivers to breathe.

There are new Swiffers Heavy Duty on the back side of the 3". five 1/2" hole on the front sides.

Sounds much better than the drivers just interspersed with random Maple blocks. Mini city scape...

This guy got a very good price on heatsink

SOLD -Soekris DAM1021

For sale in perfect condition and working order:

DAM1021-05 - REV3 0.05% resistors upgraded with VREF caps.
Audiozen Mainboard fully built with Amenaro USB.
Audiozen display and encoder -

NOTE: while taking the DAC apart for the pics it seems I have damaged the ribbon cable for the display, now it doesn't light up. The DAC works perfectly well without the display and encoder except it is locked to USB input and max DB volume. A new ribbon is all that is needed.

SOLD

Hi guys, need some help. Just got a working A&R SA200 power amp.

I noticed that a previous owner had probably exchanged the +ve and -ve fuses with M4 screws (as you would..) and burnt the rail resistors and the pcb itself. Someone repaired it.

It is working on that channel but I found that RV3 for the clip indicator is totally differently set in each of the identical channels. Whilst the one in the unrepaired channel is fully open (0.8ohm) the one in the repaired channel is set to 75k.

I am going to recap the amp and want to adjust but could do with some gudiance how this clip indicator circuit works and wha to set things to. Arcam are always good and helpful with schematics and I can find my way around their drawings but just lack the essential knowledge to work things out sometines.

The IC is an RCA 1458, the amp is from 1981 or thereabouts, it is a nice dual mono layout with proper discrete components in it.

I attach the schematic here, it's also available from HiFi Engine.

Any help, especially explaining how this part of the circuit works would be very welcome.

Many Thanks

I would like to present an Arduino-based soldering iron temperature controller that I have recently developed, and was asked by a member here to share.
It has been designed to control a 24v 50W iron, in my case an Antex TC50, although any iron with a thermocouple sensor should be suitable.



Features:

• Closed-loop temperature control, setting 25-450C (adjustable in code)
• IDLE mode maintains a lower temperature (set in code), also closed-loop
• OPEN loop mode with selectable constant power
• Display shows mode/set temperature, and current power level

The list of parts used is as follows:

• Arduino UNO R3 (any clone will do) + prototype shield
• MOSFET driver module (D4148)
• MAX6675 thermocouple interface (like this)
• 24v to 5v buck converter module (something like this)
• 16x2 LCD display with serial backpack (I used this)
• 3 buttons
• Connector for soldering iron
• Enclosure of your choice
• 24v 3A SMPS (such as this) + socket

The controller starts in IDLE mode, set to 150C.
A short press of the mode button toggles between this and ON mode, where the temperature can be adjusted via the up/down buttons.
A long press of the mode button selects toggles between these and OPEN loop mode, where the up/down buttons adjusts the power in the sequence 0-1-2-4-8-15, where 15 = full power.

If there is no valid temperature reading, closed-loop modes will set the power to zero and display 'OOR' (Out Of Range). Open-loop mode will work without a valid temperature reading, either as a backup or when manual control is desired.

The default temperatures and ranges can be modified in the code, as can the pins used for the various interfaces (The MOSFET driver should stay on pin9 as this is hardwired to the timer used).

Temperature/power plot, IDLE->ON plus some use of the iron, followed by ON-> IDLE



Example build:



Please see below for schematic and Arduino code (+ LCD library for the serial backpack I used).

Full details also on: my GitHub

Hi, everyone. First post here...
I am currently finishing the design of what i hope to be my 2.0 home theater speakers.
I have this down, so far: RSS265HF-8 in 3.5cuft ported enclosure tuned to 19Hz, another RSS265HF-8 in 1cuft sealed enclosure, sealed tweeter-mid combo (tweemid) Morel TM4055-8.
I already have the Dayton DSP 408, which i plan to use as a crossover: analog stereo in - split into "sub-bass", bass, mid and treble for left and right channels (mono bass with L-R delay correction), then feed the signal into 4 stereo amplifiers i already have.

Now... this is the setup for the testing and tweaking phase... I plan to make it pretty, which would mean hiding all those amps somehow.

I was browsing PA amps and ran into this - the t.amp quadro 500 dsp - a 4-channel amp with sufficient power and integrated DSP. The question is this - would there be any issue in using one of these for each speaker? I mean.. ignoring SQ issues with this particular amp, I am more worried about things blowing up, somehow.
Can the amp (or a typical amp, or any amp) handle such different loads on its channels? Is crosstalk an issue? Should I expect my tweeter to suddenly receive 100W worth of LFE and just go *poof*?

hi all. I'm new to this, but wanted to share my latest power amplifier project and solicit constructive comments and feedback.
my goals were to:
-design and build a fully symmetrical class A/B feedback amplifier with the simplest possible signal path.
-minimize the number of active components.
-still end up with a circuit that provides reasonable performance and sounds good.
-allow for easy upgrade to higher power output or??
Construction notes:
-D7 is mounted on one of the output transistors for thermal tracking.
-R33 is a trim pot for adjusting the output offset.
-The basic amplifier has +/- 50 volt supplies and puts out a little over 100 watts into 8 ohms.
-Optical isolator U1 controls the VAS idle current (about 10ma as drawn) allowing Q2 and Q4 to operate without emitter degeneration resistors.
-I've set the mosfet idle current to about 30-50 ma and I'm unable to detect any improvement by setting it higher.
Observations:
I've constructed the circuit as drawn and it seems to perform nicely. It sounds good to me and seems to be thermally stable with moderate heat sinking. I've also constructed a full two channel amp with two pairs of output mosfets and +/- 80 volt supplies. This amp also seems to work perfectly and the only other changes were increasing resistors R29 and 30 to 23k, and increasing the feedback resistors R4 and 31 to 4.1k.
I don't have the equipment to perform distortion testing, but it's quiet at idle and sounds good to me.
Has anyone seen a similar design using an optoisolater before?
comments welcome.

Thanks

Hi fanatics,
Having read and enjoyed a portion of the epic Giuseppe D'Appolito MTM 'Thor' thread, I hesitated more than once before registering, and hesitated again before posting this thread. My knowledge of Audio Physics extends to how to put 30 yr. old Naim connectors into their respective sockets - but I can make cabinets.
Can anyone reassure me that if I set out on an Ekta Mk11 build, there's a good chance that they will please me as much as, if not more than, my 30 yr old Epos es 22s? Are they an appropriate choice for my current amplification? i note that the DTQWTs can be built for a similar cost, but maybe they're less of a match to my system.

Naim 72 pre with Avondale Audio Audiophile 831 mod.
Avondale upgraded Hi Cap P.S.
Graham Slee Reflex M phono
Avondale Audio s100 80W(+/-)
Graham Slee Spatia speaker cables

I could use a word of advice please.

you know how it goes with the DIY "evolution"; one develops new tastes and ends up looking at his stock of parts and scratching head .

Imagine the following unlikely system: after experiencing a well tuned distributed bass at Earl Geddes's place, I decided to add two 12" subs driven by Dclass mono amps. the problem is that I now turned my 85L Elsinore speakers into mid/high units; and they do a lovely job at that (!), at the same time presenting an easy 8ohm load to an Aleph30 driven by an AlephP. the source is balanced, and my wife is not happy! (saving bold characters for what matters ).

Here comes my question: I will be looking to replace Elsinores with something a bit smaller and hopefully even better at midrange/vocal reproduction. Looking at alternatives I seem to be developing a taste for 4ohm speakers, and could use a bit more power too (probably 50w classA would do it; 100w would be better!).

originally I was planning to convert my aleph30 into a balanced F4 mono block at +-24V rails and just add another one, but 4ohm load would present a problem there, right?

running F4 modules in parallel for more current does not jive well with the balanced input though.

so after all, an alephX (or F5X), would have been a better choice??? (which would make converting my Aleph30 w/ 25V rails not possible (i.e. a new Xformer and package may be required 🙁).

What do you gents think? please share>>

I've been doing a lot of reading on clocks & jitter lately, particularly the excellent Well Tempered Master Clock thread, but have some questions for which I have not been able to find answers.

The first is how to select a decent crystal, and whether this is possible from datasheets alone or only though testing. I am talking from the point of view of identifying a crystal with respectable performance from the myriad available through Mouser/Digikey, not to target the extreme state of the art performance which can only be achieved with custom crystals, but to attain decent performance in a design where extreme cost or custom parts are not justifiable. Throughout the TWTMC thread the importance of a good quality crystal is stressed, and that particular project uses custom polished crystals from Laptech. Andrea Mori also mentions TFC crystals as good quality for a lower cost.

But looking at datasheets for those parts, what actually tells you they are good crystals vs. run of the mill crystals?

Q seems to be a big factor (high Q results in lower close-in phase noise).

The Laptech and TFC datasheets are pretty much the only ones that I have seen with a specification for Q, so I suppose this indicates they may be better quality than other crystals but is there any other information to base the decision on?

From what I have read the only way to know the Q is by measurement (which I cannot do), but ESR is linked to Q so it seems that choosing a crystal with low ESR is a route to follow.

This MtronPTI document mentions that round quartz blanks will have a lower ESR than small strips, essentially the larger the blank the better, so it seems choosing crystal in a larger package will be beneficial.

In the TWTMC thread Andrea also mentions a preference for cold-welded packages, but I cannot find any explanation of this. What is the advantage of a cold welded package over a resistance welded package?

My final question is on buffering/fan-out/distribution. NB3L553 gets a lot of recommendations and appears to perform well based on the datasheet, but many of the high quality clock designs presented on this forum just use the 74HCU04.

What are the pros and cons of each?

The basic points I can see between the chips are:
- NB3L553 is higher cost
- 74HCU04 output-to-output skew is not directly defined. NB3L553 spec'd at 50ps across its temperature range
- NB3L553 has higher output current (80mA vs 25mA)
- NB3L553 provides a phase-noise plot in the datasheet.

It seems that except for cost, the NB3L553 hold all the advantages. If this is the case why is it not used in the cost-no-object clock designs? Is it simply the case that the 74HCU04 already offers excellent performance which matches the performance of the oscillators?

Thanks

Hi all, I am new to this forum. I've built several guitar amps from scratch using the information on the AX84 site, and now I want to build a tube stereo amp for my turntable. Last week I was given two organ amps and a bag full of tubes- one of the amps appears to be a stereo amp. I have been searching images to hopefully find a schematic for days now but I haven't found any images that match- do any of you recognize this one?

Here's a pair of OTL amps that were built in the early 60's by a small company named MP Concert Installations.
The system consists of 8 chassis: pre-amp, pre-amp power supply, power amp, power amp power supply and then X2 for stereo.
I acquired these about two years ago.

Hi Everyone, I have got a NAD C375 integrated amplifier, can i get the sound quality up a little bit by changing some components in it?
What would you suggest and with which?
attaches the service manual link
NAD C375BEE - Manual - Stereo Integrated Amplifier - HiFi Engine

ONE NOS 500V 100uF + 100uF Elna Cerafine Electrolytic Capacitor. $180.

Brand New Old Stock. Never used.

Tested and measured.104uF + 102uF actual capacity.

Free shipping for USA and Canada .

Hi,

I tried to search forum but i did not find much...

Anyway, I ordered this one:

24-bit 384khz PCM NOS R2R high precision resistor network DAC fever level decodi | eBay

Now I want to put that card and a Raspberry into the chassi for my preamp. I also want to be able to connect a CD-transport and maybe some device to play FLAC-files from SSD or USB.

I am totally novice to these kind of signals, but I dont want optical signals. And as I understand it i need to have my signals in XCMOS-mode I2S(?). How is the easiest way for me to connect these device to my DAC with priority to keep high quality on the signals from CD and "FLAC-player"?

I found ways to connect, but that is thru HDMI. If I could avoid that, it would be nice. 🙂

Thanks in advance!

Regards, from Sweden

I am going over 1001 schematics for what I want to try next. The amp I just finished up is about 5 watts per channel and it seems about half as loud as my "100 watts per channel 🙄" 5 channel surround system.
Is there a factor for tube watts vs. solid state watts? I am thinking there has to be some load of bull in rating the solid state gear, like maybe peak on one channel if all the others have no signal or some scam like that.
For a room in a house 25 watts per channel of tube watts would seem to me to be much more than adequate if 5 is loud. Maybe 8-10 is fine for the next one?

I have an old motherboard with that alc887 chip. I want to remove it from motherboard and use as an usb dac. What should i do ?

I recently bought a new toy. My very first oscilloscope.

Today I attached dummy loads to my SSE speaker terminals and ran some tests. Just playing around and learning how to use the o-scope.

I decided to measure output power with different rectifiers, output tubes, triode vs. UL, etc.

Mostly I got the results that I expected regarding output power.

One thing I noticed is that the bottom of the waves were starting to clip quite a bit before the top of the waves clipped. This happened regardless of other factors mentioned.

Based on the diagram and explanation (attached) it seems that my bias voltage needs to be higher? Does this mean I should increase my cathode bias resistor value (which should reduce cathode current but increase voltage)?

I am trying to understand the balancing act going on here. It seems like if I can shift the whole wave up, to a point where the top and bottom of the wave start to clip at the same time, that would be ideal. Maybe I don't understand it?

Hello! I have some spare i found that i want to use for a stereo passive DI-box. The first thing is, i would need to mount the transformers somehow. Im all new to this DIY but ive soldered a lot of cables and patchbays a in my days but never "building" any boxes though.



Someone said doublesided tape would do but i would preferable do something more sturdy. Do i need a veroboard or can i do this with something else?


Also, if someone have a good schematic for a passive transformer DI with ground to share so i can start my buildingprocess. The do and donts, It would be very apprecitaded!

Hello.
NAD C315BEE rest in Protect mode.
The led is red.
I shorted 7 & 8 pins on protection module
and I have -30v DC on left channel.
Right channel is OK.
Where I need control.
All power transistors are OK.
Thanks.

SM.
https://www.google.com/url?sa=t&sou...FjAAegQIARAB&usg=AOvVaw0rYZaOxU9MC691wtzT_epm

I would recommend the following transistors from Diodes Inc. for all stages preceding the output stage in an audio power amplifier:

ZTX653/753
ZTX658/558
ZTX696B/796A

Because of their very high beta, the last pair are excellent for use as clamping transistors in the SOA protection circuit.

Diodes Incorporated - Analog, Discrete, Logic, Mixed-Signal

i need help understanding my impedance curves.

i simulated a tapered QWTL with hornresp then i made a quick and dirty build of the simulated design with construction grade plywood and screws. i sealed all the joints with the aluminum tape used for insulation and should be relatively sealed tightly.

its relatively close to the design, within an inch or so in length id assume and CSA is within close a deviation of a square inch or so along its length and the driver offset should be within an inch or less. i am converting from metric and stuff 😀

hornresp gives me a impedance peak at 46hz of just over 40 ohm and another at 200hz at just under 35 ohm.View attachment Hornrespimp plot.pdf

when i run the finished speaker on my woofertester i get a strange result

i cant post the screen shots at the moment i forgot to save them to somewhere i can share them from so i just have a picture of the computer screen.



confused with this i went back to hornresp and cant simulate it to look like the measured curve. i can get the peak height to be similar by shortening the line length but i cant get the peaks to move up in frequency to from 46hz and 200hz to 55hz and 150hz.

can someone explain what happened here and if i should try something to get the simulation to match the measured.

could it be speaker wire ? i used some cheap zip cord for testing ?maybe the speaker leaking i didn't do anything to seal that up its just the screws so im sure it leaks a little bit around the rough surface of the plywood.

i haven't pulled out a microphone to do any comparisons on that yet so i cant post them.

Hi all, I was wondering if there are any serious tube amp builders out there in Europe(i'm located in Belgium), who accept build to order for push pull amps? I have a pair of Tamura transformers I would like to put to use! Much thanks for any info! cheers!

For sale in like new condition fullrange drivers,one of the best out there.I have original packing boxes,so they will be shipped secure.About one Year old.Price for new units is 1600eu pair.My price is 1000 eu for pair or best offer plus shipping about 30-40eu inside EU,this are heavy.For some info and sound plese look in internet.For more info or price offer plese contact me.

I bought a vintage citronic ppx900 power amplifier one channel is ok but there is some sound problem on 2nd channel when i opened the amplifier on that is channel there were 3 pairs of k176/j56 and 6 fuses at each fet drain.1 of that fuses was blown up. I checked the fets.1 of that fets was also not working.than i disconnected the a whole pair.Now only four fets are working. Amplifier is working ok but when i increase volume of this channel i feel whizzing sound.
Any one knows what the problem is ?
Also want to mention that before disconnecting blown fet there was more sound problem.After disconnecting the sound was clear but not 100% .With increasing volume disturbance also increases.

Hi all 😀

For my next project I'd like to build a DHT headphone amplifier. My primary requirement at this point is that it use only currently-manufactured tubes - reliably acquiring NOS tubes here is becoming harder and harder. So unfortunately the likes of the wonderful 45 are not an option. Plus I intend to tinker with the project a fair bit (trying various CCSes, filament regulators, etc) so tube casualties may occur. I've thus chosen the 2A3 - I adore the sound and plenty of companies still make them. I'm open to alternatives though.

I've spent many many hours looking over various schematics, including the TSEII, the Free Lunch, and many others. Most call for tubes that have been out of manufacture for ages.

So: what recommendations do the wise have for a core circuit that uses new tubes?

At first, I'll use a standard OPT with load resistors and once I'm happy with the circuit I'll have an appropriate transformer custom wound.

4.9 million samples/second USB PC scope.
2MHz analogue bandwidth.
+/-3v3 max input but can be made much bigger with x10 and x100 probes.
100uS max time base down to 50mS.
Trigger can be none, positive or negative.
Data logger for saving stream of captures.
FFT frequency spectrum display too.
Comes with Windows software.
£20 to UK. £34 to rest of world. Paypal taken.

35w + 35w hybrid valve/tda7376b audio power amplifier
Requires heatsink and power supply.
Requires 12ax7 or 12au7 valve.
£17 plus £4 p+p to UK

Not quite sure where to put this since it ticks the boxes for so many categories, but why not this one? 🙂

Ongoing build thread for my Aurora-based "everything" box. This will contain, at the very least, the following devices:

- freeDSP Aurora
- Mean Well RPS-30-7.5
- (2x) TPA3255EVM
- (TBD) (2x) TICore260BTL
- Connex SMPS800RS

The intended use is for the Aurora to act as a USB sound card in my PC so that I can feed a stereo 4-way monitor setup.

Hi All,

I have a hankering to build some 2-way Acoustic Suspension (although I use the term loosely) speakers, with 8" woofers.

I've narrowed my woofer shortlist to two:

SB Acoustics SB23CACS45-8, and the Human Pro005.

Both of these will get me down to 39 - 44Hz with an enclosure of 41 - 43.5 litres.

The question is a little open-ended for my liking, but am I missing any tricks here?... Before I bite the bullet, does anyone have any better suggestions for woofers? 😀

Simple answer?

My digital o-scope tops out at 20V.

If I want to measure AC ripple on a 400-sh VDC power supply, will the o-scope (in AC mode) simply "ignore" the DC and measure the AC ripple - or will the 400VDC fry my o-scope anyway?

My gut says it'll fry the o-scope.

Look for IRS2092S or substitute

Good evening

Looking for a reputable source for some IRS2092S IC's. There seems to be none anywhere right now... is there another IC that has same pin layout that can be used as sort of a "drop in" substitute?

Thanks in advance.

*** Edited the part number thanks zsjkuki for pointing that out. ***