Hi guys

I will try to build a three way, I already have the mr13p mids and the satori tweeter .

I would like to use an 8 inch woofer and I have these under consideration.


Peerless hds 830869
Scanspeak discovery 22W/8534G00
sb acoustics sb23nrx
sb acoustics sb23cac
seas ca22rnx
Dayton rs225

This is a pcb removed from a mostly working unit. The headphone output was not operational and believed to be a bad OPA1622. This was replaced (badly) and didn't repair the fault, but it's likely an issue with bad hot air work. The board is mostly working, and great for a hobbiest to play with.

It contains a nice ESS DAC and a bunch of FDAs

$50.00

This is a commercial amp, 50W rating, runs off of +41 -41 v supply.
Has reasonable specs, etc., and seems like a good build.
Welcome to comment on it for any "slight improvments" such as increasing wattage to maybe 75 or 100W.

This single board is 2 amps in one. Two separate PSs, SG3525s, and outputs. Its dual mono amp. Looks like the board<s> are actually 2 channel boards that are bridged internally and then sent out as 2 channel. Seems like a 4-channel amp internally bridged. There are a bunch of faults such as all the missing and mis-matched outputs; I'll be able to easily work through, but I have a question pertaining to regulators.

When I first powered on this amp, only the LEFT side of the board produced output. The RIGHT side of the board had rail voltage but no regulated voltage hence no audio. Thats when I saw someone had removed the 15v regulators from the RIGHT side of the board. The Left & working side is using LM340T15 and LM7915CT - which I don't have any. I have LM337 and LM317 but those are not fixed +-15v.

So to be sure the non-working channel would possibly work; I temporarilly tied that side to the working regulators - and it worked. Both channels now produce audio. (Thin RED and BLACK wire)

Can I leave it like this? Amp Center Taps are tied together anyhow via the purple wire from the right Toroid to the Left non-bridging terminals. If so then I have all the parts to restore this amp fully, but I'll have to keep the regulated voltage tied, or just go ahead and order 15v regs.

Photo coming.

I sold my tube amp and want to build an SET to go with my Klipsch La Scalas. I used to be an electronics tech and can build from a schematic, and have done so many times.

Not looking for a kit, just a schematic that works. I thought of the Decware Zen but the schematics I found on line just don't look right.

There are plenty of good SET designs out there, can anyone here recommend one?

Thanks

The β22 stereo amplifier

2 modules fully populated and 1 half built PSU

100 euro + shipping

Greetings,


I finally put my hands on a pair of Marantz 4G/3 speakers. I am not sure when they were manufactured, however I see them on Marantz´s product line-up as late as 1978 or 1979. These are a three-way version of the older Imperial 4G as far as I could figure out.



The cabinets are in reasonably good shape, with the veneer peeling off a little on a few spots. Other than that they have the original and iconic foam which is fantastic





Here is a closer look at the speakers:





And here is the detail of the main speaker - definitely needs to be re-foamed:








I am trying to find the right (foam?) surrounds for them.



All and any advice is very welcome 🙂



M.

Hi all, I just picked up an abused Yamaha M-85. Here's a photo of the inside. I have since vacuumed and blow out the inside as best that I can but the main board, in particular, is still grungy.

My first thought is to spray it with isopropyl alcohol, maybe try to get a small brush in there for a light scrub, and then flush out as much of the filth as I can with more alcohol.

Is this the best way to go about it? I don't want to do any more damage than has already been done by the glue that was used to hold the larger caps down.

Thanks for your thoughts.

Hi.

I have acquired one of these.

Can anyone tell me how to dismantle it ?
I can get the turntable off but cannot see how to dismantle further.

The belt is off and it does not appear to have any life.

Any help is appreciated.

Andy

I had replaced the old 8-pin 2A3's with new 4-pin 2A3's for AI Second Audio mono blocks. And I have checked several components as recommended.

After the work, I found that the sound from the left block is noticeably weaker than the right, and I had to turn the balance nob to 10 o'clock direction to listen properly.

Here is what I have done.

1. Replace the tube socket from Octal to UX4
2. Replace 2A3 tubes with new ones
3. Change the rectifiers as recommended
4. Replace the electrolytic condensers for the heater.

During the work I have checked the electric characteristics of each step to make sure it is the same or within range, described in the First Audio schematics (which is the only reference I could get.)

When I faced the issue, I have exchanged all 2A3's of each monoblock and found the result the same. So I can guess I have issues on the left channel block.

I want any recommendation on what I need to check further or replace to fix the problem.

Thanks a lot.

Hi,

I've got an old Cambridge audio 540A amplifier. It has worked well for years, but now has a crackle from one channel. It happens about 5-10 minutes after switching on, lasts for a few seconds and then it clears back to normal.

No noise from the pots/switches/cables etc so from what I can gather it's probably one of the SAP15 output darlingtons on its way out. Googling suggests that I should replace the SAP15 with STD03 (with added 0.22ohms resistor). The plan would be to swap all 4 (SAP15N and SAP15P).

It doesn't look to be a hugely difficult job to do but I would like to know if anyone has done this mod and whether there are any pitfalls I'm going to experience (like how to set up the bias preset etc).

Or....is there another diagnosis/solution to this problem?

Many thanks

Ron

Hi!

Im workin on a active stup where I´m using an active crossover from kmtech (this NEW ! LR mono 2-way active filter by KMTech PCB DIY BALANCED/UNBALANCED INPUT | eBay) it´s essantialy this by Rod Elliot Linkwitz-Riley Electronic Crossover but no buffers on board. Since it´s recommended to use a buffer together with the 125asx2 I´m looking at adding one but then I´m wondering if it´s possible to just add one buffer before the xo instead of two per channel after the xo?

Encapsulated modules from Mark Levinson for John Curl's JC-1DC/JC-1AC/Mc Kinnie RO-III (RO-3) in faulty condition

Currently I have three defective encapsulated modules for the JC1-DC on the workbench for open and repair. I want to have some more and therefore I am looking arround for additional devices in faulty condition.
Maybe one of the members can make me an offer for such modules.
Thank you very much.

Here some links:
http://www.audiocostruzioni.com/r_s/giradischi/mark-levinson-mc-step-up/mark-levinson-step-up.htm
JC-1DC MARK LEVINSON ¥Þ¡¼¥¯¥ì¥Ó¥ó¥½¥ó ¹â²ÁÇã¼è¡¦ÈÎÇä ¥Ï¥¤¥Õ¥¡¥¤Æ² Ãæ¸Å¥ª¡¼¥Ç¥£¥ª/ Ãæ¸Å¥ì¥³¡¼¥É/Ãæ¸ÅCD/McIntosh/JBL/audio-technica/Jeff Rowland/Accuphase/¿¿¶õ´É¥¢¥ó¥×/¥È¥é¥ó¥¹Â¾¥ª¡¼¥Ç¥£¥ª¤Ê¤ó¤Ç¤âÇ㤤¤Þ¤¹ ²¼¼è¡¦ÄÌÈΡ¦°ÑÂ÷ÈÎÇä¤â¤ä¤ê¤Þ¤¹ 10-47015-67999-0
JC-1DC mark levinson ¥Þ¡¼¥¯¥ì¥Ó¥ó¥½¥ó ¹â²ÁÇã¼è¡¦ÈÎÇä ¥Ï¥¤¥Õ¥¡¥¤Æ² Ãæ¸Å¥ª¡¼¥Ç¥£¥ª/ Ãæ¸Å¥ì¥³¡¼¥É/Ãæ¸ÅCD/McIntosh/JBL/audio-technica/Jeff Rowland/Accuphase/¿¿¶õ´É¥¢¥ó¥×/¥È¥é¥ó¥¹Â¾¥ª¡¼¥Ç¥£¥ª¤Ê¤ó¤Ç¤âÇ㤤¤Þ¤¹ ²¼¼è¡¦ÄÌÈΡ¦°ÑÂ÷ÈÎÇä¤â¤ä¤ê¤Þ¤¹ 13-75831-96336-0
http://www.diyaudio.com/forums/solid-state/78843-john-curl-mc-kinnie-phono-pre-preamplifier.html
Edler Phono-Vorverstärker MC Kinnie RO 3 in Winterthur kaufen bei ricardo.ch
Mc Kinnie RO III front | Flickr - Photo Sharing!

Hello everyone,
I have acquired a first-generation ML JC-2, with a defective line output amplifier module. Tested by my technician, the module needs replacement.
Otherwise in good condition.

Could someone be so kind and point me toward directions where to find replacement modules? Or upgraded modules of some sort?
Is there someone out there who does good clones or upgrades?
That would be amazing, as I would love to make this unit play again.
Thanks so much.
Attached a photo of the faulty module in question (it's the left one).

I have a question about +/- power supplies for audio devices.
Is there a qualitative, sonic or audible difference between +/- power supplies that consist of a positive and a negative voltage regulator (regardless of whether 317/337 or +/- Superreg), or where the +/- supply consists of 2 positive voltage regulators?

It is clear to me that with a +/- supply from 2 positive voltage regulators, 2 separate taps must be available on the transformer and 2 rectifiers are required.

Is this wire factory or someone else’s work ?

This is my very first tube build ever. And I can't believe I did it!!

I'm only 22 years old, so I'm very young and new to this Tube design thing.

I have learned so mutch and now I'm addicted....

Now I can say without a doubt in my mind that my scratch built 6L6 Push Pull Stereo Tube Amplifier is finally complete with proper voltages and all!! All recycled parts. Stuff I found in parts boxes, ect. I paid nothing for the sound this amp puts out!

White steel Chassis was from head crashed 1980s hard drive😉 I drilled out by hand using just a hand drill and lots of time. As I have no punches...... yet🙂 but It kind of ended up with a "Utilitarian Vibe" which I really like.

Wiring is never final. Odds are I will never stop fiddling with this amp.

Running perfectly now at a proper on the dot, 450VDC on B+. 6L6/6P3s at 45Ma! And don't you go and say I'm exceeded the 6P3s tube specs. Most of you well know the 6P3s are touph as nails and perform well beyond listed specs. These ones I ran on my ST-70 for many months nonstop biased as if they where El34s.

Theoretically I could use the entirety of all my unused taps. And get B+ past 700V or even more if I ever needed too.

EL34s bias up and run great!! Look great!!
But I feel they don't sound quiet right with these little output trannies. Ile stick with 6L6 variants on the 6.8Kohm OPTs. And leave the EL34s too my Dynaco.

I can always swap OPT later I guess. They are very undersized anyhow and have 1x 8ohm tap. Bass could go a little deeper I think too. A slight LF rolloff for sure.

Everything else is glorious!!! Low mids/Mids are liquid gold!! The highs are actually mutch better than my early and stock Dynaco ST-70.

Very extensively detailed high end. Mabye due to 12AT7 variant Drivers, I'm not sure. But theirs a slight rolloff on my Dynaco in comparison using 6U8/7199 variants Compared to my DIY amp.

I also tried 6SN7 with an adapter. I have 2x entire Nos RCA Sleeves of short 6SN7 and Long 6SN7 I've never heared before. But it turns out 6SN7 sounds mutch better than 12AU7s in my opinion in this postion.

Something else ove noticed is how changing the driver tubes changes Feedback intensity on this amp as the resistor does 2x different things. A good way to "tune" the sound by changing tubes I guess.

I'm not upgrading that Dynaco in the video to the VTA so don't even mention it. It's a relic of time! Even with the slight high Fr rolloff. I enjoy it so mutch as is anyhow.

Anyway...
Their are 3x Total power transformers in it to get what I needed for current and voltages. Haha. But it's just about dead silent, I can't belive it. I do hear a very tiny "teensy" buz if I have my ear up to the tweeter. But only if my ear is litteraly an inch away with zero signal.

I Don't even have a choke yet, or proper capacity filter capacitors which I'm waiting for and are pretty mutch the only components I'm paying for. So this very well could just be DC not being smoothed out enough. Once I get my capacitors, and some other components ile be checking all that with my Oscilscope to "hone in" on the power supply. I'm not going to fine tune something I don't "quiet" have the parts for yet.

I have so many unused taps I could implement later on! I could get over 700V if I ever needed too. Many unused Fillament and HV taps.

Mabye a power light. Or tube VU meter. Idk yet.... any ideas? Also, I have no idea what I'm going to use as a bottom/side cover....

I have no way to accurately measure the output power. But if I had to guess. 20-25W-ish per channel
Lots of tools I will deffinitly be needing which will make my tube journey mutch easier!!

Song is "Chasing Cars By Snow Patrol". And driver tubes are RCA 12AT7s Black Plates Military.

I based my drivers and output stage on this schematic. But everything but the driver stage has been heavily changed for my own needs.

the Scheme for the drivers, feedback/bias is super weird....It's like that feedback resistor is doing double duty!! Interesing, but it works!!! DIY AUDIO PROJECTS - Do-It-Yourself Hi-Fi for Audiophiles




DIY 6L6 Stereo Tube Amplifier Sound Demo. Ohm Walsh 2XO Upgraded drivers! - YouTube

I’m interested in the Aviatrix kit from parts express which comes with its own crossover parts and design:
AviaTrix-RST MTM Components Only Speaker Kit Pair
I’d like to use this kit as the top end of a large floor speaker with an 8” woofer and a (possibly powered) 12” subwoofer. Is the kit crossover (design or parts) going to be of any use to me of should I just buy the drivers and start the XO design from scratch?

Hi

May be of interest/ value

Amount of volts needed to use Purifi amp without buffer | Audio Science Review (ASR) Forum

I was looking for a simple buffer circuit to replace the opamp in a unity gain stage of my active filter.
I found an old circuit by E. Borbely which has an advantage (to my opinion) because it uses only n-channel fets. Unfortunately the Jfets that are used were not easy to find and similar types were rather expensive.
After some searching I decided to use the J113 fets and adapt accordingly the values of the components.
The circuit was analysed with LTSpice and the final version that I built is shown in the attached file.
The measurement results were very good. After matching the two jfets, I measured the output offset at about 1mV. The maximum signal output is +/- 8 V peak and the frequency response more that 100 kHz. The distortion at 2.2 Vrms / 2 kOhm is very low, similar to the capability of my measurement system which is at about 0.015%. According to LTspice the THD is 0.003%.

Any remarks or comments are welcome.

I'm looking for good output transformers with a nice even frequency response. On the tubelabs page I've seen recommendations for Edcor, but the lead time is ridiculous. Are there equal or better options available, y'know, sooner?

I have a pair of output transformers burning a hole in my pocket, no rush to build with them but would prefer to come up with some ideas rather than selling.

They are Lundahl LL9202 gapped for 50mA. Can be wired for 6.5K, 11K, and 23K primaries. I breadboarded them in a 801A A2 design wired for 11K, but found the bandwidth due to parasitics unfavorable and have gone another direction.

More likely would use them wired for 6.5K, but sort of an oddball transformer in that case, 6.5K:8ohm at 50mA. Looking for some ideas on single-ended output tubes that might pair well with it. Despite the bandwidth issues they are good sounding transformers.

One that came to mind is the EL33 / EL3N / EL11 which I have seen used with this transformer before, although quite a wimpy amplifier even by SET standards. Another thought would be a triode-strapped directly-heated pentode, although I don't know which.

Any ideas welcome, thanks.

So I did not win the v-fet lotto and i'm trying to make lemonade out of my lemons.



I happened on a working / fully functional (measures good) Sony TAN-5550. I was going to just do some updates (caps, diodes etc), but i'm considering maybe building a new amp to try the vfets in... they are rank 58! Not giving up on the Sony, but I think a new design could do better.



I'm not a novice, but far from a expert. I probably need a design, with boards and some test points with voltages to check.



So what should I build?!

I have a JL Audio 500/1 that keeps burning up R608 a large 10ohm resistor. So I sub it with a large resistor and it heats up very quickly.

I wanted two HUF76639P Mosfets for an amplifier and found an established UK company which specialises in supplying obsolete components. They had listed Fairchild HUF76639P and after they reassured me via email they were genuine, I ordered two.

I gathered from diyaudio that a type of curve tracer is the way to go for testing, so I tested them and compared them against two original Fairchild HUF76639P.

I modified a standard component IV curve tracer (#49: Simple Component Tester using Oscilloscope - Octopus Curve Tracer - YouTube) and played around in LTSpice to get something for Mosfets. Circuit as attached. It seemed to work OK and is pretty straightforward, but should there be a film capacitor somewhere?

I initially had the 5V polarity reversed (yes, the arrow in the Mosfet symbol indicates the opposite direction to a transistor symbol arrow! 🙄) and it all took me a while, but here are the results, each screenshot is annotated. (x-axis is voltage applied to gate/source where 1 square = 1V, centre line is 0V, y-axis represents current through source/drain. Max current is seen at most negative voltage.)

Compared to two original Fairchild HUF76639P, the new Mosfets require rather more gate voltage before they respond, are not fully "on" at 3V and there is more variation between them than I would expect from genuine Fairchild devices. Fair comment? (They also look like recently manufactured devices.)

Although rather higher gate capacitance, the IRL2910 is a suggested modern replacement for the HUF and it looks like they have pretty similar response curves.

Notes:





Thanks in advance for any helpful feedback...

hello, how are you doing?

Yes, a long time ago i bought these Ciare Full range speakers, thinking one day I would build there: Dacapo
I dont have workshop, and I am no handyman, so difficult for me to build these, but now I have got some work done 🙂

also this site about these open baffle got my motivation going Open Baffle con Ciare CH250

Trying to be creative and build my own design, well...wel...
Yesterday I had the prototype up against the wall, I was going to make sure that the speakers was allright efter been lying in a store room for some years, so I plug them in to a 100W chinese amp. Well, well, what can I say, is sounds like they have "a cold" no bass at all. At low volumes its worse, but when I crank up the volume something is happening - soundstage is good, piano, voices, etc...like a typical full range, but no bass :-( there is allso some distortion, but maybee my connections and the amp is not the right kind for this speaker. Im thinking I dont want to live without the bass from a speaker, so - what to do about it? yeah the baffle is too narrow, 40cm, but I have a small living room. Maybee someting in the middel to make the wide about 60 cm? I had allso been looking at the decware nfx enclosure DECWARE / High Efficiency speaker model NFX, hmm... too difficult for me, but maybee something like that.

I have a set of 18 PCB's I bought during the last GB. The set includes the two "extra" shunt regulator boards.
I have $145 into, so I'm selling for $145 plus shipping. In USA I will use USPS Priority Mail for $11.45. Overseas, your choice since you are paying.
PM me.

Hi,

In my easy listening room, I have a pair of Kef Concerto's driven by a Kenwood Supreme 500. I love the way they sound, but they have the original crossovers and I'm feeling that they may have deteriorated somewhat since they were manufactured somewhere between 1969 and 1977. Winter is on it's way, and I have decided it is a good time to rebuild the crossovers. I'll put in my ESS AMT 1 mini towers or my Wharfedale Dovedale 3's while the recap is being done.

Now, the question is, do I rebuild the crossovers to the original Kef design, or do I try to emulate the improvements that some say were done by Falcon Accoustics, Wilmslow Audio, or some other design? To be frank, I am looking for your help on this decision.

I will document the full recap with pictures every step of the way.

I really love these speakers, so I want to put in the best components possible to within reason for these beautiful sounding classics.

I've been reading a lot on rebuilding the crossovers on the Concerto's over the last few days. Some say the caps were seriously under rated for the power handling of the drivers. If that is the case, I want to put in higher power components so that I can benefit from the additional output. But I don't want to risk blowing the drivers.

What are your thoughts?

I also don't want to lose the balance between the drivers. As it stands right now, these speakers project beautifully at all volume levels I use in this room. This is where I tend to spend most of my listening to music time and entertaining. I have no plans to modify the cabinets unless they will be hidden changes.

I'm thinking quality caps and aircore inductors, and I also intend to build a whole new circuit board so that I can compare the original with the upgraded crossovers. What recommendations do you have?

Should I follow the schematic specs or the in-unit specs?

Seeking recommendations on a complete set of tubes for my SSE build. I'm a noob here, so I'm not sure what to pick. Also haven't picked my OTs yet, if that's an issue.
I read that it makes sense to use "Starter" tubes when building the amp, so if anything goes wrong you haven't sacrificed an expensive tube.
Any suggestions?

As stated in the title. Trying to gauge interest in this torroid based power supply pulled from a Denon amplifier. Massive torroisal converter and plenty of capacitance to deliver 600+ VA's actions and positive and negative rail. (Three main wire)


If interested let me know and I can send pics if required before you make an offer.

No price yet, waiting to see what interest there is.

Any Q's ask. Postage will be £8.80 UK only.

Thanks for your interest.

I am building a 300b amp, and am building it in two parts - PS and Amp.
The PS chassis has two power transformers (one for HT, one for Regulators), and one choke. The amp chassis has two OPTs and two chokes.
What orientation conditions do I need to consider?
On the PS chassis, do I align the two power transformers and put the choke at 90 degrees to them?
And on the amp chassis do I put the two OPTs 90 degrees to the chokes?
And should I align the chokes across both chasses as they will be close to each other, or is that not so important?
Many thanks for your help

I designed a USB scope that runs about 10 mega samples/second.
The prototype ran ok but with a little noise in the signal at lowest voltage setting. It was passable so I let it go.
I had to buy in some more a2d's which were about £10 at RS.
So looked around elsewhere for some cheaper.
I eventually found some on Ali Express for about £1.50 each.
I guessed they were worth a try.
After a couple of weeks they arrived and I tried one and it is a better output than the full price ones !
People usually warn you off fakes but these ones seem to be better than the real thing.

Hello!

Left (upper) channel on my 315 recently died but for some reason works when I short hot & cold on the output - which in its turn offsets balanced gear down the line. The following item loses 5-7 db on the left channel. I guess my short circuit makes it semi balanced, or something like that?

I will figure it out!

Anyway, since it's a 25 year old beast filled with ~60 Nover 16V 100 uf caps per channel I thought I might as well recap it. Actually it doesnt use any other cap than those Nover 16/100. In & out level stages, eq stages = all Nover 16/100. The power supply use two Nover 50V 4700 uf and one 16V 4700 uf.

Any tips on what to use instead? What cap would be suitable for audio and an upgrade. I'm looking at Elna (on Mouser) RFS-16V101MH3#5

Elna are 10 mm diameter instead of the Nover 6 mm but should fit. Spacing between legs are 5 mm on both the Elna and Nover.

Or would you recommend anything else?

(the 315 also uses a lot of Philips NE5534N opamps 🙂 )

Hi, I need some help, please.

I have two of these drivers. I can seem to calculate an ideal enclosure to make a sub with them.

I purchased these about 10 years ago, knowing what I know now, I wouldn't buy them again. From the response graph, they don't look like they go down low at all.


Woofer Speaker Driver - 10 Inch | Jaycar Electronics

Seems like a shame to chuck 'em in the bin, but am I just wasting my time with them?

Data in the attached .zip file

I'd appreciate any help or suggestions

SOLD.

Never made them.
12 page plans. One full size drawing.
$25 shipped usa lower 48.

FINISHED. WTB: Scan Speak (15m/4531) Sonus Faber Cremona midrange

No longer needed.
Speakers will be locally sold.

Hello.
I have a damaged Sonus Faber cremona Midrande (WOF30001)
Does anybody here has one or two original replacement units?

Although I know they are not standard versions, a pair of scan speak 15m/4531 could be interestig to try.

The problem in the midrange is that the coil wires are broken at soldering point with tinsel leads.
I have checked continuity at the voice coil and it is ok, but the soldering point is in bad condition.
Calle me crazy, but I managed to solder a pair of wires from the voice coil to the speaker terminals (I had nothing to loose) and the driver works good, but this is not a dewffinitive fix.

Another chance: Any of you here can make a good repair or knows where to do it at a reasonable price??





Thank you

Hi
I made the amplifier part of the device whose design I liked very much. It works successfully.

Since I don't have an oscilloscope, I can't do extensive testing. In my ear listening tests, I can say that I sounded better than any amplifier I had done before.

I apologize for not being able to use the English language well.

Hi everyone,

I’m looking to do individual output mods to my beloved Tascam portastudios (488, 488 mkII, 414 MKII).. I’m curious if anyone might be able to offer any guidance... I’m just getting a start with soldering... reading schematics... identifying/sourcing/ replacing components... and generally wrapping my head around audio electronics in general.

I’m looking for any info, but ideally, specifics would be most helpful. Service manuals for all three models mentioned are available..

Thanks!

I moded my 6th order bp idea to fix that air-compression thing and here it's (just a sketch, not scaled).

Could someone please sim this for me, cos I don't know how to...?

I'm now ready to build this and looking for dimensions.

If space is your concern, I have enough space in the room to place any large of a box.

For t/s reference, here's the driver I'm gonna use.
12TBX100 LF Drivers - B&C Speakers

Thanks in advance... 🙂

I originally made this preamp for a 6AS7. The gain was as expected only 1.7. I ended up needing more gain, so simply swapped the 6AS7 for a 6BX7. Got plenty of gain, almost 20dB (18.8x), and that with a much too low value for the plate resistor.
This sounded fine and I was happy, but I knew it was not optimal with the 2200ohm plate resistor (which is ok for the 6AS7) and I finally replaced the resistor with a 3900ohm value. I also replaced the 10uF! metallized film coupling cap with a proper 470nF value foil cap. (I paralleled 4 x 3.9nF COGs just for good measure).
Much better!
The plate load should actually be higher for the 6BX7, and if the 6BL7 is to be used it really really should be higher, more close to 10kohm. But it's a compromise with the available voltage, the current I want high, and so forth. As it is it sounds plenty good.
But if done again, and not just using parts at hand, I would get a proper tube rectified supply giving at least 250V. Alternative is of course choke load the plates, which I think will be my fix, enabling me to keep the lowish 175V supply rail.

Nothing special at all, just another pre. This can take 6SN7, 6BL7, 6BX7, and even the 6AS7.

Edit: the load lines shown are with a plate voltage of 175V, so that will be either with a higher b+ rail, or with choke load.

Hi there,


I have built couple of TABAQ variations, and quite like them. Especially the softness of MLTL. Have built none of multi-way units.


Requirements:


1. Two way with the main "star" being the woofer unit. Thinking ~6 inch woofer with tweeter or quality full-range. It can be 1.5 or 2.5 way, if it works.
2. Passive crossover.
3. Size is no limit! Any size, any size of the baffle, any shape of cabinet. Full size floor standers. No need to go high WAF but that does not mean that it has to look weird.
4. 40Hz F3 is ok, no need to go much lower, but will need to sound at least OK without woofer.
5. MLTL, TL, Horn or other. Everything works except open baffle or bass reflex. Also no line arrays for now. Pls no flame about this, this is personal preference, like color of cabinets. 🙂
6. The budget for drivers and crossovers is up to ~300-400EUR per pair, that is the same in USD, as the drivers tend to be cheaper on other side of the pond.
7. There has to be balance between the quantity and quality of sound, preference on... hmm.... maybe quality 60%, quantity 40%.
8. It will be driven by class D amp, but must sound well with others.
9. Drivers have to be available in EU.


Right now leaning to building 10F/8424 & RS225-8 FAST / WAW Ref Monitor MLTL version but still not decided. There is not much other on my mind...


Any advice is ok, be generous 🙂

Hello,
Could somebody know something about crossover for this ribbon Tweeter?
Key Features
Compact planar ribbon tweeter driver
High output and exceptional treble definition
Surface or flush mount installation
Potent neodymium magnetic design
Supports 4,000 Hz crossover, 12 dB/octave

Hi,

I replaced the 4 pin output socket of my unimproved 3009 with RCA jacks. Instead of connecting the ground wire to the ground socket I soldered it to the ground terminal of the left channel jack in order to avoid a separate ground wire from my preamp to the tonearm.

Is this correct, I want to avoid hums.

Cheers,

New In Box, Never Mounted

1 Pair Tang Bang W3 - 881SJF 3" Full Range Speakers

Asking $33 with USPS Priority Mail and PayPal fees included.

These usually retail for $35 each without shipping.



Typo: 3" not 3'

Just finished refurbishing my dad's pre/power amps and am hooked 🙂

For my next project I would like to build a pre/power amp combo, starting with a preamp. There are so many options that I am getting a bit lost. Can anyone recommend a preamp build with the following criteria:

1. transistor-based (not valve) and class A, obviously
2. no phono stage, tape monitors etc
3. bass and treble controls
4. preferably sonically compatible with a good class A/B power amp
5. good/high quality

Many thanks!

I was taking a look at the MA graphs for various drivers (as you do) and I was struck by how useful the CHR90 frequency response could be.
First you have the built in baffle step response which all MA fans will be familiar with. Then we have a dip that is centered around 4kHz which seems to match up to the Fletcher Munson curves. Then there is a bit of a boost at around 10kHz which may be useful depending on your age.
Anyone else think this dip at 4kHz may be a good thing?

Anyone have one they would part with?

Thanks.

Hello all,
I have moved into a new place and am concerned about line noise. I do NOT have a dedicated line for my audio /video system (all low level source electronics, amps, TV, cable box (TV, internet). But this line only supplies the above and a few lighting receptacles. In addition I am adding a noise filter receptacle (audioquest) on the 1st in this chain.

In a previous question (which I cannot locate) about how to hook up the audioquest receptacle someone had recommended another line treatment that could be installed (Cdm???). ANY recommendations is greatly appreciated.

Hi, since this forum offered such great advice on my last project I am turning to you again in hope for some help.

I had this amp for a year now and I am rather satisfied with it.

Joyo AC-40 - Google Photos

There is only one problem: A permanent background hiss as soon as I turn it on at around 30db (background at 20db). I usually play this amp at volume 2, so its no biggy. But I would like to understand and fix if possible.

IF I turn up the volume of the MIC channel, the hiss increases a bit (about 7db at max volume). That seems to be expected.

But hear comes the funny thing and that I REALLY would like to get rid of.

IF I turn up the guitar volume at 5 a zing (or beep) is added that changes frequency as I go further. It peeks (frequency and volume wise) at 7 at 42db and is gone back to the "normal" background noise at 9. It sounds a bit like tuning an old radio.

I tried to record it with my phone. CAREFUL LOUD!

Any help on diagnosing/fixing this is greatly appreciated!

I am sufficient with a soldering iron and a multimeter, if that is of any help.

Suppose a DAC is driven in such a way as the following:

Since a DAC essentially converts a binary string into a voltage or current, and this is done every time a binary string is presented at its input, it makes sense to hold all digital inputs at a logic 1 if the succeeding bit is also 1. This should avoid having the corresponding bit going down and up at the arrival of the next binary string. So, it goes something like this:

If the present bit is 1 and succeeding bit is 1, hold the input bit at 1. If the next bit is 0, drop the input to 0 normally. The same holds for successive 0 bits. This, according to my logic, should minimise some noise issues at the output.

I am selling a clone of the Norwegian amplifier Electrocompaniet AW180. A differential amplifier powered by stabilized voltage. It will play several thousand amplifiers. Bias 450mA. 40.000uF for channel.Toroid 450W for channel.Price for amp 1300€

Hi all.
Didn't post for some time, being busy with non related audio stuff.
Under what topic should I post my Open Baffle DIY constructions (Not for sale, at least, not for now, since I am now in Vietnam and will be returning to Montreal, Canada in one to two years.)
Need to know how to post pictures ?

Hi All,

i need to capture audio from an external amp into android.

I made a cable which connects mono out to mic, got a normal 4 pole to 4pole cable, chopped halfway then joined speaker from Source to mic on recorder side (Android phone)
its working fine but i have couple of issues and needed help to find a better stable solution

1: audio has noise, any way to cut it? (to be honest i can live with it, its not extremely critical, point 2 is more)
2: i have noticed weird behaviour, if i plug android side first then it uses the cable to record audio but if source side is plugged in first then android cable then it doesnt detect and uses builtin mic only.
is there any way or official cable i can use, this is quite annoying as this setup is not mostly used by tech people so they can plug cable in wrong sequence and app not to work.
thanks in advance.
kaleem

Hi all,
I have modelled a little 6080 amp with 5687 drivers and all is well in LTSpice.
However when analysing my results it is obvious that the 5687 is a bit marginal to get full power out of the 6080's, so I decided to try substituting a 6DJ8 for the 5687.
At this point the model refuses to run failing with "Time step to small". How can two valve models behave so differently in exactly the same circuit ?

Shoog

Well, you didn't win but here's a shot at building one of the "vfet-less" kits. I've got a pair of 2sk82 KD-33 vfets that I'd like to donate.

Rather than giving Papa or Jason any more work;

Procedure:
You: Respond to this thread, first come first served.

Me: If you're first in line, I will respond and give you my email.

You: Will donate $100 to one of the two charities, and email me your receipt and paypal me $1 (so I can print a shipping label with your address).

Donations to two great charities – diyAudio Store

Me: I ship them to you. CONUS only, because I'm also covering the cost of shipping here.

Hello, we have put together a port velocity calculator for round flared ports.

You can input port radius, flare radius, port tuning frequency, enclosure volume and velocity speed at an unflared port that I personally calculate on WinISD
The spreadsheet will then calculate port length for one flared end port or two flared end port and ofcourse the new port velocity.

Enjoy!
T5B Sound team

port_velocity_calculator_3.xlsx | Failiem.lv.

Just wondering,

I have a British DAC, a little Beresford Caiman SEG towards which I grew an antipathy, I don't need the headphone amp, don't like the external brick called Dorado nor I like the power brick, nor the led lights which make it look like a xmas tree, insomma, I don't like it any longer if not for the versatility of inputs, two SPDIFs, one USB and one Coax.

Now, given I need no high-end nor whistles and bells, one box fitting it all with a decent number of inputs, unbalanced outputs, will feed signal through a MacMini for LossLess music via USB and a TV and AppleTV through SPDIF, very basic.

Is there anything which can be built at home with decent sound quality and meeting the above requirements?

Grazie


Giovanni

Hello all!

Since I've been shunned to far away lands without my usual gear I've been fooling around with some transistor-based circuits in an effort to learn and hopefully make something cool sounding.

After building some fuzzfaces and rangemasters I started 'hacking' together a schematic for a positive-ground germanium preamp. When I say 'hack', i really mean it. But, to my surprise, the dang thing works and already sounds pretty good, considering.

My current issues and questions are these:

1) The variable resistor between the two gain stages works just fine up until about 95% of maximum volume and then just squelches out until there's no volume. I tried different pot values (1k to 500k) and increasing voltage from 9v to 12v - no change.

2) The frequency chart below says that this circuit is inherently dropping off pretty quickly under 200hz or so - how can I lower this? I want 80hz. (Note, I am using 2N527 transistors).

3) Since this is a total hack job, what could I do to improve it? I'm getting some good, colorful gain out of it at this point, but what are some options to try out and what have i done here that might be redundant or counter-productive?

Thanks and hope everyone's been doing great

Had my 368 as my entry into hifi and its awesome....but after looking around for more power, options being a c268 to bridge 300w per ch OR go with the new tech (which I prefer) being purifi amps. So c298 or more economically something like the VTV eval 1........BUT

has anyone opened up a 368 and just replaced the amp module with purifi amps? would the stock power supply handle this or would you swap that out for the SMPS that they usually come with?

i like the idea of hot rodding an amp and making it a sleeper 😎

thanks in advance


dan

If a audio dual matched transistor pair is used at the i/p of a balanced amp and each half fed with the two differential phases of the i/p signal, will the alternate heating and cooling effects on each device cancel out due to their proximity.

can we assume that the two devices are close enough for this to occur ?

can anyone think of any drawbacks of such a scheme ?

would the cancelation cover all relevant frequencies ?

does anyone know about this kind of stuff ?

mike

Hello, I've just left every experiment in DIY and bought one beautiful brand pair of speakers with dual chamber reflex:

Given my modest experience, it seems to me that reflex frequency is quite high, being speakers a bit boomy if not far from rear wall, and I would appreciate a suggestion to try lowering it. For my knowledge, a dual chamber reflex is made by a little chamber where is driver with a high frequency tuned vent opening in a big chamber with a low frequency tuned vent, opening out. So the first vent lets pass a larger band of frequency, after reduced by the second one.
My new loudspeakers seems to me exactly opposite: a large chamber with driver opening in a small chamber, so my questions are:
- how are the low frequencies filtered by the first low-pass vent able to pass through the second high-pass vent?
- where have I to work around to decrease the lower tuning frequency of cabinet, on the first or on the second vent?
Thank you very much.

Hallo,
I want to know the new products from Bumper/Zeuz. The old website is to find about
splash

I find only this website with a example of transducer:
12'' DC FR Series Woofer 1250Wmax - www.cybermarket.co.uk
additional
EARTHQUAKE SOUND CORPORATION vs. BUMPER INDUSTRIES
EARTHQUAKE SOUND CORP. v. BUMPER INDUSTRIES - 352 F.3d 1210 :: PreCYdent Search Engine

The last Adress, what I know was follow
BUMPER INDUSTRIES INC. USA.
8113 NW 54th. ST. MIAMI, FL. 33166
TEL: 305-592-3999 FAX: 305-593-1499
E-MAIL: bumperind@aol.com
...........WEB SITE: bumperspeakers.com

My delivery source and Bumper's european distributor 10 years ago was "ALTAI" in U.K. In the attachement the correspondence regarded new distributor and similar models from Zeuz (not Zeus)

A special feature was the ultimate ratio of price/quality and 10 years warranty

Perhaps one of you can find out for me the currently website of Bumper/Zeuz transducer - Thank you very much

In the process of removing the PCB board from my 300B amp, I learned that the cheapo wire insulation melted at a MUCH lower temperature than needed to unsolder the damn things... On top of that, there was so little room to get the iron in.

I think its best to solder tails on the board using ptfe or silicone coated, and splice in the leads where there is a bit more room, with double heat shrink... Thing is, I may want to go in and out a few times... Got me thinking, does anyone know of any type of disconnect or barrel plug that can be used to facilitate easy connecting / disconnecting of wires in a tube amp ? The B+ is 450v and the amperage is relatively low. I see connectors for 1kv and much higher amperage for electric cars, but dont want to spend $80 per!

If you've spent enough time in the Pass Labs forum, you will undoubtedly see references to Greedy Boyz. Since it's 2021 we should revise this or at least be considerate and start calling this group Greedy Kidz but that's not the point of my post.

If you are a Greedy Boy or Girl, you already know you are but if you are unsure, how do you figure that out? 😕😕😕

Feel free to share why you consider yourself a member of this nefarious group and wear your badge of dishonour honourably (yes it's Canadian spelling).

Being a fan of Papa and Wayne also does not qualify you as a Greedy Kidz, in fact, it's a prerequisite but it's the ability to take this to the point of 'too far' that will gain you this privilege of joining the undeserving.

I am one of the Greedy Boyz (or Girlz or Kidz if you don't care to identify) because I think the best amp is the next one I haven't built yet and I"ve built at least 1 of Papa's creations, enjoyed it, basked in it's glorious sound and then started researching the next one.

Please note, using the accolade 'fugly' alone doesn't qualify you as a Greedy Kidz but if you disagree, please feel free to explain.

As the creator of the term, I defer to the Mighty Zen Mod (MZM) to arbitrate 😀

Moderators, if any of this is inappropriate, please feel free to remove/lock

A device to boost the low end depending on level for closed cabinet.
With circuit diagrams and examples.

Greetings to all!

After several years of yearning I finally put together a lab to unleash my love for 70's electronics, and why not, audio.

Today I put my hands on a pair of Marantz speakers and a Magnum stereo.

Let's see what surprises await us.

Seventies.

Hi guys,

I have for sale audio oscillator Leader LAG 126S
- the item to have some signs of cosmetic wear, but is fully operational and functions as intended
- included original printed user manual

ship to: only EU
price: 370 EURO ( ex-work incl. shipping and paypal fees )
payment options: paypal

contact: milandks at pobox.sk / slovakia

regards
milandks

Hi,

I'm about to buy a pair of vintage full range drivers from the late 50'
Both drivers are 8 ohm and were connected in parallel on a push-pull 6BQ5 mono amp. in a console with a turn table.

What I'm wondering is that the unit (Zenith console) is using 2 drivers which have differente cone construction even though they were both manufacturered the same year and by the same manufacturer.

One cone has a radial seam and the other cone is a one piece cone, no seam.

I have seem in many occasion this configuration in Zenith console, using 2 full range drivers located close to each other but with different cone construction…

Both drivers have the same basket, frame material, magnet type and size..

Why go to the trouble of using 2 slightly different drivers ? Any idea why would a manufacturer would do this ? I have some ideas but would like to hear yours first.

I'm probably making too much out of this but I keep wondering the reason for doing such a thing.

If there is sonic differences between the 2 cones, I would prefer to know now before moving ahead with this purchase.

Thanks,
Eric

How does this happen?......................................


content of message deleted by Moderation.

Just compare

Mundorf Mresist Ultra

https://hfc-fs.s3-eu-west-1.amazonaws.com/s3fs-public/mundorf_mreu_30_datasheet.pdf

Isabellenhütte PBH

https://www.isabellenhuette.de/fileadmin/Daten/Praezisionswiderstaende/Datenblaetter/PBH.PDF

Furthermore Mundorf is describing that the above mentioned resistor was developed together with a Resistor Company known for Laboratory Grade Production.

The used Alloy can be considered as Isabellenhütte Manganin

Everything fits.

p.s.: Price of course is not the same

Hi, I have traced my full range speaker and I simulated the baffle step diffraction using Loudspeaker Design Software . I want to blend it using FRD Blender and Minimum Phase Extractor . The problem is that I only have Excel 2011 and everytime I load the spreadsheet, I always got an error message and can't find the upload frd button.

Can anyone help me blend this file? The file for the woofer will be named woofer.frd and the file that I got from simulating using Loudspeaker Design Software will be named Baffle step diffraction set as loss.frd and Baffle step diffraction set as gain.frd

Thanks!

Today I plan to drink half a bottle Absolut Vodka.
Proud as I am it is a Swedish vodka.

So far I have taken 2/3 of half the bottle (375ml).
I feel rather good, as you can imagine.
Cheers or as we say in Swedish: Skål!

I'm building a balanced preamp using TI DRV134 receivers, OPA604 opamps, and OPA134 line drivers. I don't know what value of dual pot to use for the volume control bridging the DRV134's to the OPA604's? Thanks!

Hello,

I want to make a mono summing RCA cable to connect my audio interface/DAC to a mono amplifier. The input impedance of the amp is 30kΩ, the input sensitivity (2Ω, 100W, 1KHz) is 0.83V. The source max output level is +16dBu and i do not know its output impedance.

What value resistors should I use? Do I need a resistor on the summed output that goes to ground? What is the purpose of this resistor (can be seen in the schematic below)?



The amp is a wondom model WONDOM | STORE

The audio interface a Motu M4.

Does anyone know a company that carrier this tweeter online or otherwise. I am looking to buy two of them for a pair of two way tower speakers. Thanks in advance!

here is a schematic for a ocb that goes between my volume autoformer and the knobs. It uses Nixie tubes to display vol knob position. I have an option to use external 5 volt power you can set with a jumper. other than that its pretty straight forward. Just feel better if I get a few more eyes on it.
Thanks in advance!

Jeff

Hi guys, looking to upgrade my cayin 300b headphone amp anyone got this amp and tube rolled ? I want the best available. Thanks

I intended to do the right thing by replacing the old power supply caps in my model 3 amp. What I found were some caps that are much bigger in value and size, and voltage. The originals are 24,000 with a 60 volt surge rating. The new ones are 37,000 with a rating of 100V. After replacing the caps, the amp immediately blew the 8 amp main fuse. I then put a 6 amp current limiter in the incoming AC line after the fuse. It still blows the main fuse. I am thinking that I would be better off just getting 24,000 uf caps of the same voltage rating and calling it good. Any thoughts?

This is on a Harmon kardon Citation 11 Preamp. Replacing the Electrolytes I also tested the Jfeds with a Transistor tester. It is testing as 2 resistors consistently. The board still had output but engaging the EQ was noisy.\

It is Q506. It, Q508 and Q510 all are the same part number and test as P-Channel with symbol gate pointer close to the source lead.
As much as I have read tells me the company which made these was bought up years ago. The numbers are P1053 215 above Mfgr symbol 7233. Unable to cross reference.

I see lots of people put those cheap VU meters off ebay on their tube amps, but was wondering if it is possible to use a decibel meter for the same purpose, as i have some awesome vintage decibel meters and would love to incorporate them into a steampunk styled build.


Doesnt really need to accurately measure VU or anything, but just really to serve as a level meter to give some sort of indication to how much the amp is being driven.


Would they require shunting, or just hook up across the output?