QUAD UPGRADE
Allan and Joyce Jose
I WAS WONDERING IF IT IS POSSIBLE TO UPGRADE A QUAD 405 AMP
THANK YOU FOR YOUR HELP
--=20
**********************************************************
Allan and Joyce Jos=E9 H: (703) 904-0293
1305 Northgate Square F: (703) 904-0294
Reston, VA 20190 C: (703) 909-0384
Wan Siu Chung & Louise Tung
In the circult has a coil, it can replaced by some hard core speaker
cable made coil. And someone say that replace the power capcitor with
higher grade products, but size may be is a big problem.
Allan and Joyce Jose <all...@erols.com> wrote in article
<5ud5mh$m...@canyon.sr.hp.com>...
Stephane Tsacas
Allan and Joyce Jose <all...@erols.com> writes:
> I WAS WONDERING IF IT IS POSSIBLE TO UPGRADE A QUAD 405 AMP
The 405mkII is an upgrade of the 405. Faster op amps etc. Maybe
upgrade kits are still available from Quad, but buying a 405.2 is
maybe the easiest solution.
,
Stephane
--
slt Stephane Tsacas, Institut Curie
@curie.fr 26 rue d'Ulm, 75248 cedex 5 Paris, France
@lpbc.jussieu.fr +33 01 - 42 34 6772 / 6758 (Fax)
http://www.curie.fr <<PUSHJ P, POPJ P, recursively>>
Leslie Wolstenholme
In message <5ud5mh$m...@canyon.sr.hp.com>
Allan and Joyce Jose <all...@erols.com> writes:
> I WAS WONDERING IF IT IS POSSIBLE TO UPGRADE A QUAD 405 AMP
> THANK YOU FOR YOUR HELP
The answer is an emphatic yes..!!
Begin by removing all the rather fragile wiring from the case and
making a new wiring harness using a thicker gauge of cable.
Remove all the input and output sockets and replace by some more
robust versions. At the same time, inputs may be converted to phonos.
The main caps will be quite old by now and the Philips 114 or newer
154 components will be found to be an exact replacement size for size
(80mm High X 52mm Dia).
The series 1 and series 2 boards differ very little in architecture so
to begin with, don't bother buying the newer boards if you have the
earlier model.
Begin the board mods by changing the op amp for an OP27GZ/GP,
preferably the one in the ceramic package. I know there are many and
various more expensive and sophisticated op amps on the market but
this one sounds just super in the 405.
Decouple the two zeners D1 & D2 to earth, these provide stabilisation
for the op amp voltage rails. A couple of 47uF 25volt Oscons across
both R7 and R8 (taking care to observe polarity) will reap dividends
here.
Remove and discard the two BC214Cs, TR5 and TR6, the associated diodes
D3 and D4, R25,26,27,28 and 29. These form the current limiting
circuitry and impose a very definite signature on to the performance
of the 405.
The inductor L2 is an essential component in the output bridge
arrangements and should *NOT* be altered.
Change the capacitor C2 for a 100uF Oscon and the associated feedback
resistor R5 for a bulk foil variant. C10 will best be renewed by a
non-polarised electrolytic.
Reseat the output transistors on ceramic pads using a slight amount of
fresh transfer compound.
Renew the ceramic caps in the circuits for polystyrene variants and
the input cap C1 for a good grade of polypropylene.
Rewire the loudspeaker outputs in silver plated PTFE insulated cable
of 19.030 gauge or similar and the input cables could be changed for
some 'far out' wire if desired.
Don't forget the earths, (grounds to our ex-colonial cousins) at the
input phonos or a hum on the output will result.
Carefully check all the work and in particular, the voltages of the
main rails. These should be in the order of plus and minus 50 volts.
A good move at this point is to remove the front heatsinks (2 off) and
renew the old dried up heatsink compound after a thorough cleaning.
Refit the boards using fresh heat transfer compound and new shakeproof
washers.
Insert some half Watt 3.3 Ohm resistors into the fuse holders and
power up the amp. Check that all is well at the outputs.
Fit some new fuses of around F5A to the boards and check that there is
less than 3mV offset at the loudspeaker terminals.
In following the above procedures, the 405 will show a clean pair of
heels to many well regarded commercial offerings.
Although the amp cannot be made totally neutral in absolute terms, the
performance of our upgraded 405 has suprised many a delighted owner
when returned to them.
For the more adventurous, this conversion may be taken even further by
changing the resistors for suitable metal film precision components
and by providing the op amps with a dedicated regulator system running
from a separate power source.
Wishing you good listening.
Les W......>>
Bernd Ludwig
Leslie Wolstenholme <avon...@zetnet.co.uk> writes:
>In message <5ud5mh$m...@canyon.sr.hp.com>
> Allan and Joyce Jose <all...@erols.com> writes:
>> I WAS WONDERING IF IT IS POSSIBLE TO UPGRADE A QUAD 405 AMP
>> THANK YOU FOR YOUR HELP
>The answer is an emphatic yes..!!
>Begin the board mods by changing the op amp for an OP27GZ/GP,
>preferably the one in the ceramic package. I know there are many and
>various more expensive and sophisticated op amps on the market but
>this one sounds just super in the 405.
Try also BurrBrowns OPA604 !
>Decouple the two zeners D1 & D2 to earth, these provide stabilisation
>for the op amp voltage rails. A couple of 47uF 25volt Oscons across
>both R7 and R8 (taking care to observe polarity) will reap dividends
>here.
Ooooops! Don't do that! The caps have to be across the diodes (I think
it was a slip of the 'pen'). The decoupling is absolutely necessary
indeed with fast OPs, otherwise they will oscillate. To my experience,
100nF do a very good job here.
Quad did a number of substantial corrections to the circuit during the
405-production. They should be checked. Above ser. Nr. 59000 the 405
is identical to the later 405-2 except for the protection-circuit (and
PCB-layout-details of course). There are only two interesting
innovations during the 405-2 production: An additional diode between
the bases of T9 and T8 and 75 Ohms across L2 (I have checked the
shematics up to issue 9).
If anyone is interested: I compiled all the mods I did with success.
Bye
--
Bernd....@UniBw-Muenchen.de
LIEUTENDGN
Replacing the power supply bridge with fast recovery diodes will improve
the PSRR.
Leslie Wolstenholme
In message <5v8f80$b...@agate.berkeley.edu>
s81b...@kommsrv.RZ.UniBw-Muenchen.de (Bernd Ludwig) writes:
I'm grateful to Bernd. for the suggestion of the Burr Brown OPA 604.
I've never tried this one but intend to do so as soon as I can.
The paragraph about the caps being across the resistors is indeed a
slip of the keyboard (serves me right for typing at two in the
morning) and the preceding instruction which refers to decoupling the
two zeners is the correct procedure.
Dunno about 100nF though, a bit low value in my experience (I have
converted 127 405s to date) although the majority have the extra power
supply for the +15 & -15 volt rails.
As I mentioned in the intro to the convesion data, the Quads vary very
little between MK1 and MK2 models and again Bernd. is indeed correct
in pointing out the additional diode which Quad slipped in for good
measure in the MK2. The extra diode BTW merely serve to increase the
quiescent current though the class A stage.
Sorry for any misleading info.
Good listening.
Les W.......>>
Avondale Audio.
Mike Ford
In article <5v8f80$b...@agate.berkeley.edu>,
s81b...@kommsrv.RZ.UniBw-Muenchen.de (Bernd Ludwig) wrote:
> Leslie Wolstenholme <avon...@zetnet.co.uk> writes:
[ quoted text deleted -- jmv ]
> >Begin the board mods by changing the op amp for an OP27GZ/GP,
> >preferably the one in the ceramic package. I know there are many and
> >various more expensive and sophisticated op amps on the market but
> >this one sounds just super in the 405.
>
> Try also BurrBrowns OPA604 !
What about just going to the 606 amp, or is it completely different, not
just improved?
How about updates to the 606?
Bernd Ludwig
micha...@usa.net (Mike Ford) writes:
Just an other cup of tea: more power, much more expensive and I never
heard anyone complain about the sound (while the 405 is often
characterized as a liveless performer). The 606 is hard to get second
hand at reasonable price (at least here in Germany).
>How about updates to the 606?
No idea, I never looked into it. There was a 606-2 two or three years
ago, and now it advertised as 707 (so it fits 'numerically to the new
77 series by quad). The 606/707 is the only piece of
pre-1995-quad-electronics that survived the fusion with mission.
NB
Quad-solid-state-amp-nomenclatura:
X0Y where X indicates the power-range and Y the 'generation':
303 (~1967, 45W), 405 (1975, 100W), 306 (~1985, 50W), 606 (~1985,
150W)
The '22'-tube-amp (second generation) was in production from 1956 to
1966 and replaced the amp without number, the Acoustical 'QU(ality)
A(mplifier) D(omestic)'. So we have now indeed the 7th generation of
Quad-amps after 50 years.
--
Bernd....@UniBw-Muenchen.de
Leslie Wolstenholme
In message <5vbssr$l...@jamesv.Warren.MENTORG.COM>
micha...@usa.net (Mike Ford) writes:
> What about just going to the 606 amp, or is it completely different, not
> just improved?
> How about updates to the 606?
Just as easy as the 405 he said, (reaching for the Quad Service Data)
if you can wield a soldering iron.
The main problem with the 606 is that the power supply is effectively
capacitor coupled to the loudpeaker. Although the circuit shows a
conventional plus and minus, dual rail supply, the actual centre tap
of the supply is manufactured electronically. The reason for this is
that the intrinsic design of the amplifier module does not clip
symmetrically and for the boffins at Quad, this will not do.
They therefore contrived to have rails of two different voltages so as
to ensure that clipping occurred at the same amplitude on both rails.
(To hell with the sound, just make sure it measures right..!!) seems
to be the official party line.
Right then, off we go.......
The original models of the 606 had installed a 'C' core transformer
and if one slits the waxy covering (where all the sleeved windings go)
along the centre and peel back, the ends of the secondary windings can
now be accessed. By a process of testing with a continuity buzzer,
the appropriate centre tap for each secondary may be located. Extend
these by soldering a cable and connect these to the appropriate pair
of capaictors - C12, C13 at the common ground.
Remove and replace the secondary fuses FS2 by links, if desired.
You have now constructed a conventional dual rail power supply whose
centre tap no longer relies solely on the impedence of the capacitor.
Remove and discard these components:
T15, T16, R36, R37, R38, R39. These form the original centre tap
generator circuit and are no longer required.
Take care that the two decoupling caps C9, C11 have a common ground
connection. This is acheived by soldering small links into the PCB at
appropriate places.
Ensure that a connection is made from the centre of the main caps to
the boards at the position where the orange cable exits the PCB.
At this point, the loudspeaker return (orange cable) should be given a
path direct back to the centre tap on the main caps and not follow
Quads senseless route from the PCB.
Decouple the two zeners, D2, D12 to ground by 10uF 20v Oscons,
observing polarity of course. The low voltage rails which supply the
servo IC1 must be of the highest integrity, this alone has perhaps the
greatest effect on the 'signature' of this amplifier.
Decouple D1 to ground by a 100n polyprop.
Change C4, C6 for polystyrene or silver mica versions.
C7 may be changed for an correctly rated non-polarised variant.
Replace the 100n input cap C2 by a 1uF polypropylene to improve bass
response.
Rewire the entire shooting match with some 'far out wire' and the
varmint goes like a train - it sounds beautifully sweet and natural.
For the purist, the only minus effect is that one peak clips before
the other however, you're not supposed to be that far up anyway.
Hope that helps.
Good listening,
Les W........>>
Avondale Audio.
Jan Didden
LIEUTENDGN wrote:
>
> Replacing the power supply bridge with fast recovery diodes will improve
The PSRR is a function on the opamps used, the amplifier topology etc,
but has nothing to do with the power supply. Generally, one would use
fast diodes to get a clean 'switch-off' of the diode current when the
diode voltage reverses as the input waveform starts to go down. A
cleaner switch-off makes for a cleaner supply line, which may or may not
be audible. When trying this, you want fast SOFT recovery diodes. Use
the DSEK 30-06 from IXYS for instance, 2 diodes, common kathode in a
TO247, 30A RMS, 600V max.
Jan Didden
Stephane Tsacas
s81b...@kommsrv.RZ.UniBw-Muenchen.de (Bernd Ludwig) writes:
[...]
> Quad-solid-state-amp-nomenclatura:
> X0Y where X indicates the power-range and Y the 'generation':
>
> 303 (~1967, 45W), 405 (1975, 100W), 306 (~1985, 50W), 606 (~1985,
> 150W)
http://www.quad-hifi.co.uk/history.htm
for some picts also.
The 50E (mono bloc, 50 W ?) is missing, and a few others <pro>
models I know they exists
Richard D Pierce
In article <5vm297$n...@jamesv.Warren.MENTORG.COM>,
Stephane Tsacas <s...@lpbcsun.lpbc.jussieu.fr> wrote:
>s81b...@kommsrv.RZ.UniBw-Muenchen.de (Bernd Ludwig) writes:
>
>[...]
>> Quad-solid-state-amp-nomenclatura:
>> X0Y where X indicates the power-range and Y the 'generation':
>>
>> 303 (~1967, 45W), 405 (1975, 100W), 306 (~1985, 50W), 606 (~1985,
>> 150W)
>
>models I know they exists
For the record: the 50E was a 50 watt mono transformer-coupled
laboratory amplifier providing 50 watts into any impedance (suitably
rewiring the secondary taps) from 2 to 200 ohms. Not particularily
low-distortion, not particularily good sounding, but absolutely
rock-stable into anything. I've used mine to directly drive a 120 VAC
synchronous motor, and in the high-impedance position, it will swing
almost 200 volts into a high impedance.
--
+---- Dick Pierce ---------------------------------------------+
| Professional Audio Product Development |
| Transducer Design and Measurement |
+---- (781) 826-4953 (Voice and FAX) DPi...@world.std.com -----+
Martin Leese - OMG
On 12 Sep 97 18:02:43 GMT Bernd Ludwig (s81b...@kommsrv.RZ.UniBw-Muenchen.de) wrote:
...
>> The '22'-tube-amp (second generation) was in production from 1956 to
>> 1966 and replaced the amp without number, the Acoustical 'QU(ality)
>> A(mplifier) D(omestic)'. So we have now indeed the 7th generation of
>> Quad-amps after 50 years.
Just to be anal about this, QUAD = Quality Unit Amplifier Domestic.
This is according to a QUAD brochure.
Regards,
Martin
* NEW * E-mail: mle...@unb.ca * NEW *
WWW: http://www.omg.unb.ca/~mleese/
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