Designing the biggest, most euphonic set of transformers?

[JohnRoberts]

Yup AMR Studio line had serious brand and distribution problems. Too many ugly stories, and TMI for this thread.

Yes, the VMP pre, and a companion tube compressor/limiter (VCL?) done around the same time were quite nice but burdened by a very wrong dealer base, wrong brand vibe, wrong everything. I suspect they are still getting used today by people who manged to listen past the brand name. I didn't do the tube designs but nudged them in a good direction.

I was hired to do recording products, but my best sellers were MI sound reinforcement gear, while I did all kinds of stuff. How many people on this list have designed, or will admit to, a Karaoke unit?

JR

 

[bcarso]

[quote author="JohnRoberts"] How many people on this list have designed, or will admit to, a Karaoke unit?
JR[/quote]

Well, Brad Plunkett once told me about a non-audio thing he did for someone that embarrassed him so much he said he'd prefer his kids think that he trafficked in slaves.

It really wasn't that bad IMO, but since he didn't believe in it he felt compromised.

I'm actually pretty happy with the computer audio stuff I did for Harman over the years. Things did deteriorate a bit when industrial design triumphed over the audio requirements. One time it actually worked out to advantage, with the curvaceous character of the enclosure reducing diffraction. It would have been a pretty nice nearfield system if it could have been married with a subwoofer, but the consensus was unless said box was bundled with the pair to begin with, virtually no one ever bought the add-on.

 

[Dan Kennedy]

I did a disco dance floor lighting controller.

Forgive me father...

 

[SonsOfThunder]

Sorry for crashing the thread, but this is great discussion that pertains to the same subject really.

You designer guys make me understand one thing clearly: the stupidity (or my perception therof) in the industry that I work in is just the same in other audio industries as well!

Subwoofer amps are the best illustration of this fact. The lower the impedance that the thing will handle, the better it will sell because kids like low damping factor (<50)...it sounds louder.

>>>It should sound glorious. F*&k accuracy.

Can I use that quote as my forum sig?

Peace!
Charlie

 

[JohnRoberts]

[quote author="Dan Kennedy"]I did a disco dance floor lighting controller.

Forgive me father...[/quote]

I did a DJ mixer "Kit" back in 1978 for my kit company...

I didn't personally design any DJ mixers at PV, but engineers who reported to me did... It's a real business spending real $$.

JR

 

[bcarso]

[quote author="SonsOfThunder"]
Subwoofer amps are the best illustration of this fact. The lower the impedance that the thing will handle, the better it will sell because kids like low damping factor (<50)...it sounds louder.
Charlie[/quote]

The most amusing thing I ever did with a sub amp was when someone said the competition just (insert appropriate phrase meaning "was superior to") all over us...

I measured their amp and their control inserted about a 23 dB boost at about 50 Hz. So I duplicated it and the customer was happy.

Following what Dan says, Lord have mercy upon my soul.

 

[JohnRoberts]

[quote author="bcarso"]

The most amusing thing I ever did with a sub amp was when someone said the competition just (insert appropriate phrase meaning "was superior to") all over us...

I measured their amp and their control inserted about a 23 dB boost at about 50 Hz. So I duplicated it and the customer was happy.

Following what Dan says, Lord have mercy upon my soul.[/quote]

That reminds me of an incident back at my old day job, when one of our big european distributors was complaining about our local competition over there having a "Euro" bass curve built in, that we should look at. I checked out the unit and it turns out the knobs on the tone control's splined shaft were tooled for vertical orientation and they were using them horizontal. Therefore the knob pointer was not pointing straight up at mid rotation and commanding boost when set for flat.

I suspect the consumers didn't mind the slight boom/sizzle but the distributor was suitably disspointed to learn his local product was too cheap to tool the correct parts and not tweaked for local market preferences.

JR

 

[PRR]

> I changed to a newer longer BBD, but it was from the same vendor and same technology so I expect only slightly lower distortion from that with similar characteristic.

BBD lines are a LOT of unity-gain amplifiers in cascade.

Distortion rises exponentially with number of stages.

0.01% per stage times 256 stages is 2.6%.

0.01% per stage times 1024 stages is 11%.

The New And Improved is very significantly worse.

I'm not sure that 0.01%/stage is even likely on low-volt CMOS. I dimly recall THD plots which were not good-looking, though not real "bad" if it were simple distortion: I could never listen to BBDs for long, all tizz-fuzz.

> I have never heard IM distortion that I found remotely euphonious.

It is a musical tool for simple few-tone sources and post-modern ears.

Ever use a Ring Modulator? There are more awful sounds in there than you can imagine, but occasionally you find a useful one.

Rock guitar amps can IM out the wazoo and be favored for "thick tone".

Heavymetal sounds can be nearly all IM, and while my ears tire quickly obviously the stuff is marketable.

On a related note: observing low-price speakers in high-level uses, and specifically dance rehearsal studios, I note that users turn-up to an acceptable (high!) level of Doppler FM, no matter what the speaker. If given a truly ample speaker, they run deafening power levels, while also being content to use few-watt one-way boomboxes at very modest acoustic power. They don't need 100dB SPL peaks, they need 25% FM peaks. May be a need to highlight the beat.

> even simple square law circuit ...will have 6dB higher IMD than THD. ...provide me with a link to magickal circuit that has substantial enough THD to be called euphonic but is almost IMD free.

You can slant the ratio of IM to HD by splitting the band into many small bands. I'm not sure there is a general solution for musical signals which would be remotely feasible.

 

[JohnRoberts]

I wasn't adequately precise.

I switched from 4x1024 to 1x4096 BBD. Parts were the same technology from same company. My suspicion is one long line probably similar and if anything better in practice, due to less I/O conversions, more consistent bias, etc.

I'm sure I looked at their specs at the time, but that was a few decades ago... My recollection is the overall circuit did measure better, but it was never what one would consider a pristine audio path.

JR

 

[dshay]

I'm a noob who lurks to soak up some of the rays around here, my input wouldn't normally be worth squat, and this is kind of a tangent, but....

I spent a short stint at a college radio station as chief engineer(which means engineer apprentice)...

Anyways, due to the physical limitations of the radio microwaves they can only go down to a certain frequency level.

High end processing/filters for radio by companies such as Orban have an option to take the frequencies below what radio can reproduce and induce 2nd harmonic distortion so the sub isn't completely lost. It's an effect also used by old style church pipe organs, ghosting notes, someone referenced to that earlier. It's an option usually employed by 'urban adult contemporary' stations. (ouch, I hate the demographics of the business.)

Some pop music producers/engineers and many mastering houses(Orban is common there) anticipate radio's limitations and induce this type of 2nd harmonic themselves. It also helps out boomboxes that wouldn't typically be able to carry those frequencies with their woofers.

But this is a totally different application, and like JRoberts suggests, in Orban's case it's an option/function with a bypass.

 

[bcarso]

Check out in this connection "MaxxBass", a patented process that looks at low frequency energy outside the system passband (or very attentuated) and adds harmonics, at least a few in the harmonic series. I don't much care for it myself.

 

[mikep]

[quote author="bcarso"] I don't much care for it myself.[/quote]

me either, but I did use it once. on a piece of electronic music I did for a TV commercial.

IMO there is a similarity between the maxxxbasss process and the type of LF distortion you get running thru transformers.

mike p

 

[bcarso]

And then the MaXXXbass process, for porn soundtracks...

 

[CJ]

now come on, Brad, I have three Sanyo ghetto blasters that i love so much, why?
they are all the same model, and they all have MaxxBass.
i even pulled one out of the dumpster that needed a new pwr jack.

sprayed it down, but nobody left.

 

[PRR]

> due to the physical limitations of the radio microwaves they can only go down to a certain frequency level.

Surely an economic limit.

Probably using "FM". FM can handle DC just fine.... except that stray DC appears to put you off your assigned carrier frequency and you get a ticket.

Probably no ticket if you stay in your band, but it adds uncertainty for no good audio purpose. They'd rather lock to a crystal. But then what is the definition of "locked" on a signal that is allowed to wander? A low-cut, obviously.

(Worse: they could be using Phase Modulation. Averaged over eternity, the carrier will BE the crystal frequency. But you can slip/push/lag the beat for a while. But the deficit accumulates. So an octave deeper bass means twice the apparatus.... you pick a bass cutoff number and stick with it.)

Since old FCC only required Proof to 50Hz (and no longer cares), and hardly any home speaker will do an honest 50Hz (bcarso's clients the rare exception), that's a fine number for the link designer.

Since a few DJs/PDs on a few tracks can hear the bass-loss over the link, there's a market for a button, something short of a link replacement, especially if it can be tossed in on something the PD was already lusting to buy (the latest over-processor).