Good Article re Vinyl Renaissance

[MarkWComer]

the cheap stylus was a total turnoff

All of those junky ones are conical point. Absolutely horrible on the inner grooves. The tonearm offset is such that it won't hit any wrap of the spiral at 90° to begin with. They shouldn't be sold for more than $5. They shouldn't be sold- PERIOD!

A lot of them come with software to detect the silent sections of the groove and automatically cut the files into tracks. I needn't say any more about that... I wonder how many tracks I'd get from Tangerine Dream's "Rubycon"!

 

[laatsch55]

Thanks for that- off to the record store for LZII on Wednesday.

BTW- How did you get a WOPL 1000? I assume you started with a PL700 and changed (transistors?). 300 watts above specs!

Mark, 700's typically did 450 before clipping. The clipping spec can vary from 470-525 depending on rail voltage. D2's WOPL had rail voltage of +/- 108.7, one of the highest I've seen. His tested at 525 at clipping.There is a little extra gain in Joe's work and I'm just guessing it's around 15-20 watts a channel. Mostly it's rail voltage. I have a pair of mono blocs in the planning and parts acquisition stage that will have rail voltage right at +/- 120 volts. . That should put it around 600 WPC into 8 ohms. My push in the design is to double down into 4 ohms, as the present power supply only supports 775 watts per into 4 ohms. The power supplies in the mono's will be slightly larger for one channel than the power supply was for the stereo version. I will use a 700 chassis for each channel and parallel the two channels worth of outputs , using 22 output devices for one channel. Should deliver plenty of current even into a 2 ohm load.

 

[MarkWComer]

Mark, 700's typically did 450 before clipping. The clipping spec can vary from 470-525 depending on rail voltage. D2's WOPL had rail voltage of +/- 108.7, one of the highest I've seen. His tested at 525 at clipping.There is a little extra gain in Joe's work and I'm just guessing it's around 15-20 watts a channel. Mostly it's rail voltage. I have a pair of mono blocs in the planning and parts acquisition stage that will have rail voltage right at +/- 120 volts. . That should put it around 600 WPC into 8 ohms. My push in the design is to double down into 4 ohms, as the present power supply only supports 775 watts per into 4 ohms. The power supplies in the mono's will be slightly larger for one channel than the power supply was for the stereo version. I will use a 700 chassis for each channel and parallel the two channels worth of outputs , using 22 output devices for one channel. Should deliver plenty of current even into a 2 ohm load.

You're a sadistic speaker murderer, aren't you?
How many voice coils have you fused into solid rings of copper?

​

I continue to be impressed! Rail voltage- can be changed by altering the transformer, correct? But then, components further along the line will have to be able to handle the increased voltage. I'm not an expert in this, but understand what you're saying.

 

[laatsch55]

It's not so much about speaker destruction Mark as it is handling very large transients into a more difficult lower ohm load. My bud , Stephen in Phoenix has some hard to drive 4 ohmers with lots of dips into the 1-2 ohm range. He wanted an amp that will drive them at high levels all day long. The transformers will be 2-800va toroids and 4 35,000uf caps per channel. I have consulted with Joe about his driver board and backplanes being used with those voltages and all is good. Maybe a component change or two but nothing major. It will be an interesting build which i hope to get to later this spring, and have them done in time to take to the RMAF in October...

 

[MarkWComer]

The transformers will be 2-800va toroids and 4 35,000uf caps per channel.

...FrankenWOPL! Mazel Tov on the project!

Tell me if I'm correct here: Higher resistance (16Ω for example) should create a denser magnetic field in the coil, thereby greater cone excursions. Lesser resistance (4Ω) also means easier electron flow but lesser mag flux, and therefore, reduced volume. Is this the difficulty in hard driving lower impedance speaker systems? What are the advantages and disadvantages of either impedances? (as I said, I'm not an electronics engineer.)

 

[Lazarus Short]

I continue to be impressed! Rail voltage- can be changed by altering the transformer, correct? But then, components further along the line will have to be able to handle the increased voltage. I'm not an expert in this, but understand what you're saying.

At such levels of power, circuit traces, which are fusible elements, need to kept in mind as well as caps, resistors, etc...at least, I would worry about it.

 

[laatsch55]

Neither am i Mark, but from what I've learned, lower ohm loads increase the current loads on an amp. resistances in speakers coils represent winding length in the coils. Those wild dips in resistance on a freq response curve have a lot to do with resonance and a bunch of other things i don't quite understand. I do know lower ohm loads require more current while maintaining the same voltage, ergo more current...Joe could probably explain the current demands on an amp a lot better than i could....maybe I can get him over here...

 

[laatsch55]

At such levels of power, circuit traces, which are fusible elements, need to kept in mind as well as caps, resistors, etc...at least, I would worry about it.

Laz, Joe built so much robustness into his designs, there is no sweat on the added demands of the mono's.....

 

[MarkWComer]

Neither am i Mark, but from what I've learned, lower ohm loads increase the current loads on an amp. resistances in speakers coils represent winding length in the coils. Those wild dips in resistance on a freq response curve have a lot to do with resonance and a bunch of other things i don't quite understand. I do know lower ohm loads require more current while maintaining the same voltage, ergo more current...Joe could probably explain the current demands on an amp a lot better than i could....maybe I can get him over here...

More knowledge only shows that there's more to know.
Yes- got it (sorta). Higher current flow! Also, inductance plays a part in the whole equation, the voice coil being driven by opposing magnetic fields also creates a current of its own due to the coil moving in that selfsame magnetic field. Zoebel networks are intended to counteract that effect (a tip o' the hat to Don Imlay for that nugget!).

 

[MarkWComer]

At such levels of power, circuit traces, which are fusible elements, need to kept in mind as well as caps, resistors, etc...at least, I would worry about it.

Hmmm. A huge resistive grid, perfect for frying yer sausage 'n' eggs. Surely a cause for concern!

 

[derek92994]

Hmmm. A huge resistive grid, perfect for frying yer sausage 'n' eggs. Surely a cause for concern!

Haha, I've managed to hit nearly 200 watts of clean power driving into my 75 watt JBL 4311b's. I have experienced 'woofer crack' which is a warning not to go any harder. Its good to know the limit and stay below that for the sake of the voice coils/cones.

Here is the thread on the amp build. http://forums.phxaudiotape.com/showthread.php/5422-Derek92994-s-700-Ser-II-White-Oak-conversion

Lee is a very patient man. A clare brothers 700b which was in a truck roll over was shipped from melbourne australia to lee in the states without the transformer (big thanks to George), this was to save on shipping costs. The transformer was sent from melbourne to brisbane australia for me to attach once the completed amp got here (with the guidance of Lee over the forum, my soldering skills left something to be desired). The amp was given a full restore with new parts and chassis, a faceplate was also required. More details are in the thread I just linked above.

 

[Elite-ist]

Thanks for the heads-up on the article, Laz. In our small town of about 18,000 residents, records, old and new, are being purchased faster than I've ever seen. Last year, a store opened in town selling used records and new vinyl releases. I rarely buy new records and opt for originals. I do receive LPs, many of them remasters of older titles, for birthday and Christmas gifts. I am just not impressed by the new vinyl and that includes a few notable ones that have been recently released.

Nando.