From larr–(at)–erakusa.com Tue Aug 22 09:24:54 CDT 1995
Article: 3032 of alt.guitar.amps
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From: larr–(at)–erakusa.com (Dr. Nuketopia)
Newsgroups: alt.guitar.amps,alt.guitar,rec.music.makers.guitar
Subject: Blues Deluxe review (update on Holy Grail)
Date: 21 Aug 1995 19:40:21 GMT
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Thanks for all the comments about my search for the Holy Grail sound.
Weighing all factors, I bought a Blues Deluxe on Friday. Traded my
Performer 650 in and walked out with a new-in-the-box Blues Deluxe for
under $300, tax included.
I have to say this is pretty darn nice sounding amp. It’s not the Holy
Grail, but its a good deal for a small price. At least it has the right
kind of tone. It does get a very legitimate classic tube tone. This amp
is also quite loud, and works very well at high volume levels. It has the
classic Fender tone, with a few modern updates to lower cost and provide
1995 features.
Noise levels, both hiss and hum were acceptabley low. This amp sounds ok
at low levels but gets really sweet when cranked. Though it is built well
enough for gigging and such, it lacks some features for hard-core road
warriors. One is the tubes are not held in by spring retainers or
sheilds. The outputs have base clips, while preamp tubes are partially
recessed for sheilding. It’s certainly tough enough for jamming, and
around-the-town gigs.
Here’s the tech review:
3 – 12AX7 Sovtek
2 – 5881 Sovtek
Signal path is all tube, though Reverb is driven by TL072 Audio chip. The
reverb pan is the long spring type.
The effects loop is bufferd by TL072’s. Not using the effects loop
bypasses the TL072 buffers, so the signal path is tube-to-tube.
One button footswitch control to switch between drive and normal channel.
Has 2 inputs, #1 is high-impedance, #2 is low-impedance, 1+2 together is
high impedance for both.
Chassis construction is a good quality fiberglass PC board, with tube
sockets soldered on a sub PC board. Component side of chassis is exposed
when the tube guard is removed. Single-sided PC board is well layed out,
road-mapped on top, solder masked on bottom. Board removal is about 5
screws, plus all the nuts from the top panel jacks and controls. Chassis
has *plenty* of room for mods. Transformers etc, attached by plugs to PC
board, should make servicing easier.
Cabinetry is particle wood, with a multi-core pine plywood speaker baffle
(either a 1/2 or 5/8 thickness just looking at it.) Baffle is attched by
6 nuts and screws to the cabinet.
Circuit features:
Power:
AC supply has an NTC thermistor in line to limit inrush current on turn
on.
Silicon diode full-wave bridge develops primary plate voltage of 427v,
loaded into to 100uf–(at)–50v caps (series for 50uf), then a choke, feeding
2 more 100uf caps which feeds the screen supply, then a resistor divider
network for the pream stages.
Filament and pilot are derived from a 6.7vac winding, ground balanced by
2-47ohm resistors.
A 50 volt winding supplies zener regulated power to the TL072 chips and
channel switching chips, along with the negative bias voltage for the
output grids. The negative bias is non-adjustable, taken between a 3k and
27k resistor divider. (this needs a tweek) Bias is fixed at about -46
volts.
Signal:
The amp offers 2 channels, with footswitch operation. The normal channel
is simple volume, tones, reverb. The drive channel includes a drive and
master volume as well. The preamp employs 3 gain stages, leaving one
section of 12AX7 unused.
The amp does not implement discrete channels for drive and normal, but
employs 2 small relays to switch the master volume and drive or the
normal volume controls. Switching also effects the gain parameters of the
pre-amp stage, adding a bit of boost in drive (though not too much).
The reverb is driven by TLO72 opamps, configured in a send/receive pair.
Reverb is after volume and tone, and mixes in at the phase inverter.
The amp has fixed level effects loop, with a non interrupting pre-amp out
and a interrupting amp in jack. The loop is buffered by a pair of TL072
op amps. However, if the amp-in jack is not used, the signal bypasses the
loop buffers for a tube-only signal path. (nice touch)
Phase inverter uses two sections of a 12AX7, configured in a differential
pair, rather than the more common single section voltage divider
inverter.
Output is provided by 2 Sovtek 5881/6L6 wired in a conventional push-pull
pair. No provision is made for measuring idle current or adjusting the
grid bias. Screens are powered through resistors to the choke side of the
power supply.
The transformer has 4 and 8 ohm taps, though only 1 speaker jack is
provided, using the 8 ohm tap. The 4 and 8 ohm transformer taps are
easily swapped however, so changing speakers should not be too much
trouble. The output transformer is kind of smallish, but looks to be more
than adequate for the job. Power is rated at 38 watts RMS–(at)–khz with no
more than 5% THD.
Output stage negative feedback is coupled through the presence control,
which alters the frequency curve of the feedback signal. Feedback is
applied at the input of the phase inverter.
Speaker is one Gold Label Fender by Eminence “vintage re-issue” (tweek
candidate).
Overall quality of components and workmanship is pretty good. I’d have to
say this amp represents an excellent value. List price is around $650,
though street price is around $420. It’s also covered by a 3 year
warranty.
—
Dr. Nuketopia
Technology Director of the World-Wide Monetary Conspiracy
Opinions strictly reflect the party line
From larr–(at)–erakusa.com Thu Aug 24 15:03:14 CDT 1995
Article: 3099 of alt.guitar.amps
Path: geraldo.cc.utexas.edu!cs.utexas.edu!swrinde!news.uh.edu!uuneo.neosoft.com!usenet
From: larr–(at)–erakusa.com (Dr. Nuketopia)
Newsgroups: alt.guitar.amps,alt.guitar,rec.music.makers.guitar
Subject: Re: Blues Deluxe review (update on Holy Grail)
Date: 24 Aug 1995 16:55:41 GMT
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In article <41g6ti$qh--(at)--aygull.rtd.com>, bdaniel–(at)–td.com says…
>
>Solid state reverb in a Blues Deluxe? Wanna bet? I just checked my Blues
>DeVille (same setup as a Blues DeLuxe) and there a very nice Accutronics
>reverb pan in the bottom of the cab. Now, the reverb drivers and
>recovery in both of these are op-amps, instead of tubes, but this would
>not give the same sound as a solid-state reverb (I gots one of those,
>too, so I know the difference.) A tube send and recovery would be nice,
>but then the amp would probably sell for $75.00-$100.00 more with the
>tubes, and Fender’s price point would be missed by quite a large margin.
>
Yup. Adding a full tube reverb would easily add $100 to the price, maybe
more. A good audio IC can do a very competent job with reverb.
Maybe I wasn’t clear enough in the review.
TL072’s are high-quality, FET input, low-noise, high slew rate, small
signal audio op-amp chips made by Texas Instruments. As op-amps go, they
are pretty darn good, suitable for hi-fi and other demanding audio usage.
These chips are most definitely anolog IC’s. They perform the same
function as a tube section and a bunch of resisistors and caps and such.
Since they cost about a buck and do a pretty good job, I’d have to say
Fender was pretty smart to use them in this manner to save money.
The reverb pan in the Deluxe is the same one used in Fender’s better
amps. It’s the long Accutronics, not the skimpy little short one used in
the cheaper amps.
The reverb system is totally analog. It uses solid state IC’s to drive
and recover the reverb signal from the pan.
NO delay chips are used, analog or digital.
The TL072’s are used to bufer the effects loop jacks too. This too is a
smart idea, it cuts cost, and IC’s are better able to deal with the
widely varying impedances and loads external devices are likely to
present. The power amp-in jack is wired in such a way that if you don’t
plug in anything, the op-amps are bypassed, sending the signal from the
preamp tube stage on to the phase inverter tube. That’s a pretty nice
touch by the engineer. The Fender of the past would have just cheesed the
signal all the way through the IC’s.
Now, if you are a purist, the Blues Deluxe (and DeVille since they share
the same PCB and design) will pass the signal entirely through tubes if
you:
A: Do not use the effects loop.
B: Turn reverb control all the way down (or off)
Use it like this, and the circuit is very similiar to the early tweed
Bassman amps. Eerily similar actually.
Though I apreciate the sound of tubes, there are cases where IC’s make
sense. I think the Blues Deluxe design makes wise use of 1995 technology,
while still retaining a very legitimate tube design and sound.
Cheers, y’all
—
Dr. Nuketopia
Technology Director of the World-Wide Monetary Conspiracy
Opinions strictly reflect the party line
—
Dr. Nuketopia
Technology Director of the World-Wide Monetary Conspiracy
Opinions strictly reflect the party line
