BH car amp

[xcortes]

Is the car amp an idea that we can genuinely expect to materialize someday?

On the same lines: what would be the problem(s) of placing a mainline BH amp in the trunk of the car and connecting it to a "pure sine wave" inverter? Heat? Microphonics? None of the above?

[ssssly]

The first issue that comes to mind for me is speaker efficiency. Car audio largely relies on forcing large amounts of wattage into very inefficient speakers and enclosures to compensate for the lack of space in a car. Car audio speakers have also evolved to be very power hungry with huge magnets and super stiff suspensions.

The few manufacturers that I have seen that attempted in car tube gear implemented huge push pull amps. All of which encountered problems with excessive heat production in addition to sketchy sound due to vibration related tube microphonics.

You could probably make a system that would sound good while the car was sitting still but it probably wouldn't cut it once you started driving around.

That being said, I implore you to ignore my pessimism, give it a shot, and let me know how it works out for you. I would suggest using high efficiency speakers suitable for open baffle configurations and a huge bass horn in the trunk that can play well into the mid range (at least 3-400hz) since you will get almost no bass out of open baffle speakers in a car door that near field.

[xcortes]

I implore you to ignore my pessimism, give it a shot, and let me know how it works out for you. I would suggest using high efficiency speakers suitable for open baffle configurations

I already have a pair of Altec 775s so efficiency shouldn't be an issue. And I'm planning on putting them using the trunk as a box indeed. That should probably get me down to the 50s hz, more than enough for me.

There's these guys from Milbert that have been very successful with their push-pull amps claiming long life and no microphonics. They have been selling the amps for many years so they should do something right. I'm leaning towards one of them but I don't mind at all buying some "old shool" (that's how the car audio guys name them) cheapo SS amp while waiting for a BH product, if there's chances it will happen eventually.

[Mikey]

Hi Xavier,

As far as I know, Milbert is the only game in town for a true vacuum tube amp.
However, there are good hybrid alternatives out there, like the Tru Technology Copper series (no longer in production):

http://www.trutechnology.com/products/copper/c74_t.htm

I've used their products in the past, and John Yi is one of the good guys in car audio.
Prototype installation photo below:





I'm sure Paul B. will chime in with a few other suggestions.....

Mike

[Caucasian Blackplate]

I'm sure Paul B. will chime in with a few other suggestions.....

Yeah, the idea has been kicking around a bit.  Tru Tech had a push-pull EL84 amp in the copper series, but form factor and heat is always an issue.  (The Milbert amps are large with perforated chassis).  If you have the space, I would start by trying a power inverter and a 300B amp to see how you like it.  I will probably end up doing a 4 channel push-pull amp with 15 volt filament tubes, and lots of them.  It seems like I can get enough B+ off an inverter to an isolation transformer, and a doubler...

I wouldn't bother using tube amps for the bass.  In a setup I had some time ago, I had a 4 channel amp with 15 watts per channel driving midwoofs/tweets and a very, very large subwoofer amp.  Despite the power differences, the midwoof/tweeter combo was efficient enough that it wasn't a problem. 

[pboser]

Let's not forget Bob Danielak's tube amp in his Fiat x1/9 at NY Noise in 2001!  It was a variant of his Darling amp, IIRC.  There's a little picture here: http://www.enjoythemusic.com/nynoise2001/secondgroup.htm , but I thought there was more on the enjoythemusic.com site.  Also can't find Bob's site, because it was formerly on Geocities, which is now gone.

[xcortes]

Thanks guys.

I have enough parts to rebuild my Parabees so it looks like a nice project. I've read about the hybrids Tru Tech and should be nice. I also came across the US Amps hybrid and isn't that expensive to use while building/testing/repairing, etc the DIY amps. You familiar with them?

At least they are good at wording what to me seems like a voltage amplifier followed by a buffer:

You may know that a transistor is a
modern, efficient, less expensive version of
a vacuum tube, which is the device that made
sound recording and reproduction possible in the
first place. Now, the electronics industry has been
trying for many years to equal the sound quality available from tubes. They have
been able to make transistor amps louder, cooler, more abusable, and less expensive
than tubes, but to this day, they’ve been unable to make any solid state amp
sound as good as a tube amp.
So, our engineer got to wondering, “What if I combined the sonic character of a
vacuum tube with the drive capabilities of solid state?”
Well, the result is the U.S.Amps’ VTCSD hybrid amps. Using the signal path
directly out of the tubes as a “steering” signal and the following drive signal wave
from the transistors as the “motor,” with absolutely no negative feedback as a
corrective to the transistor’s waveform, we achieved the most detailed, pleasing,
articulated sound available in mobile audio today.
VTCSD “follows” the high voltage tube signal STRAIGHT INTO THE SPEAKERS,
adding only current in a form of “amplifier power steering” — free from voltage gain
or negative amplifier feedback!
Vaccum tubes are renowned for their high dynamic range and smooth emphasis
of even-order harmonics. The transformer-less VTCSD circuit brings out hidden
qualities of the vacuum tubes, including excellent frequency response, smooth
“clipping” and high signal-to-noise ratio.
VTCSD divides audio signal amplification in two separate areas, voltage and
current. By starting with the vacuum tube as a source of high voltage(vacuum
tubes operate at four times the voltage of transistors), VTCSD adds a second
solid-state “amperage amplifier.” The “amperage amplifier” is a null-gain circuit
driven by “current syncs” that mirror the voltage signal and provide “torque” to the
speakers in perfect synchronization with the voltage content, that neither distorts or
colors the original tube sound!
The result are astonishing. All of the intensity, transience, and frequency
response of the vacuum tube, which can operate at MUCH higher output voltage
than audio transistors.

As a source I'll be using a Nak TD-1200SE:

[Grainger49]

Xavier,

Cool Player ! ! !

Reading the clip you attached, I would say your assessment is far more on the nose than I would have come up with.  Sounds like a cathode follower, low gain all current drive, to me.

I'm probably wrong but I have always heard the voltage gain in most amps are in the driver stage(s).  I have heard that most output stages increase the "current drive" of the amp.

Like I said, I will probably be proved to be wrong.  

[TheSparkle]

I wonder what how a car system would sound with pre-outs running through a Quickie preamp then on to the rest of the system...