Hi All
I have picked up 2 Quad ii power amps.I have fired them up and they sound lovely.However as it was last serviced by Quad in 1984 (although used very little since then)
I guess some bits will probably need replacing.
I would like to keep the outside pretty standard looking and not cut any chassis so am looking into iec mains socket and phono input that can fit in the holes already there.
In terms of components I am going to replace R12 180R with a 6.5 watt Vishay Dale Wirewound and the C5 22uf with a modern electrolytic.
In terms of the valve coupling caps(0.1uf )are Ansar 630v ok to use?I understand I have to add a 1nf cap in parallel with R11 if i use non metal body caps for C2 and 3.
Also if anyone has experience does the quality of C2 and 3 affect the sound quality.
Many thanks for any help.I will measure the resistors tomorrow and poss the main caps might need doing.
I have had my multimeter and lots of transistor amps but as I have had a few shocks in my life I think a good regard for the voltages in the Quad may be advised..
Appreciated
John
I have picked up 2 Quad ii power amps.I have fired them up and they sound lovely.However as it was last serviced by Quad in 1984 (although used very little since then)
I guess some bits will probably need replacing.
I would like to keep the outside pretty standard looking and not cut any chassis so am looking into iec mains socket and phono input that can fit in the holes already there.
In terms of components I am going to replace R12 180R with a 6.5 watt Vishay Dale Wirewound and the C5 22uf with a modern electrolytic.
In terms of the valve coupling caps(0.1uf )are Ansar 630v ok to use?I understand I have to add a 1nf cap in parallel with R11 if i use non metal body caps for C2 and 3.
Also if anyone has experience does the quality of C2 and 3 affect the sound quality.
Many thanks for any help.I will measure the resistors tomorrow and poss the main caps might need doing.
I have had my multimeter and lots of transistor amps but as I have had a few shocks in my life I think a good regard for the voltages in the Quad may be advised..
Appreciated
John
If the amps works i would advice against tampering with them.Hi All
I have picked up 2 Quad ii power amps.I have fired them up and they sound lovely.However as it was last serviced by Quad in 1984 (although used very little since then)
I guess some bits will probably need replacing.
I would like to keep the outside pretty standard looking and not cut any chassis so am looking into iec mains socket and phono input that can fit in the holes already there.
In terms of components I am going to replace R12 180R with a 6.5 watt Vishay Dale Wirewound and the C5 22uf with a modern electrolytic.
In terms of the valve coupling caps(0.1uf )are Ansar 630v ok to use?I understand I have to add a 1nf cap in parallel with R11 if i use non metal body caps for C2 and 3.
Also if anyone has experience does the quality of C2 and 3 affect the sound quality.
Many thanks for any help.I will measure the resistors tomorrow and poss the main caps might need doing.
I have had my multimeter and lots of transistor amps but as I have had a few shocks in my life I think a good regard for the voltages in the Quad may be advised..
Appreciated
John
If you don't like my advice read
QUAD II Valve Power Amplifier Information
first to avoid the usual mistakes.
Quad II
Hi. Later a lot of search and builds this is my ultimate amp driving one wonderful ESL57. Both (amp and ESL) give me almost live music sensations (with limitations of course)
Hi. Later a lot of search and builds this is my ultimate amp driving one wonderful ESL57. Both (amp and ESL) give me almost live music sensations (with limitations of course)
Attachments
I would agree with Petertub, the Quad 11 was designed to work in harmony with old Quad electrostatics.
While components don't last forever -Dont say as seems to happen nowadays --"I will up-rate it by fitting --xxxx-yyy-zzz", keep values the same , I have the original designers thoughts on his design and a good bit of thought went into it .
If you ignore the advice it will no longer be classed as a "Quad 11 " but a "circuit off the internet ".
While components don't last forever -Dont say as seems to happen nowadays --"I will up-rate it by fitting --xxxx-yyy-zzz", keep values the same , I have the original designers thoughts on his design and a good bit of thought went into it .
If you ignore the advice it will no longer be classed as a "Quad 11 " but a "circuit off the internet ".
Don't change the circuit, but no reason not to have an earthed mains lead. I put a laptop style main connector behind the fuse hole, and fitted a fuse and one-off switch in the main voltage selection hole. A couple of small holes to hold the mains socket. The idea was no metal cutting, and to keep all the power connections at one end, by the transformer.
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Thanks for all the advice everyone.I think ill fit an iec socket and phono input.The speaker sockets can stay.I dont intend to change the circuit or any values anywhere.Im just a bit worried about some components failing and doing further damage.It was serviced by Quad in 1984 so that makes some components at least 37 years old.Thanks again.John
Hi Smiffy, as you can see at pics I change all parts (when I got both quad2 resistors were in bad state, some broken). So I got AMRG resistors and caps from old russian stock. The global sound is better than a lot of amps I built (VFETs, tubes) and now I have security that parts are new and must work years..
Detail, stage, and other very fuzzy audiophile terms that I do not understand are spectacular with old ESL57.
I am very very happy with global sound.
Best
Detail, stage, and other very fuzzy audiophile terms that I do not understand are spectacular with old ESL57.
I am very very happy with global sound.
Best
I will.Room is 11ft x 9ft i think.
Going to check some voltages in the Quads tomorrow.At the mo the main prob is the Quad 22 pre amp.Prob one is the interconnects keep falling out the back.Also the 6 pin Jones connectors dont stay in the Quad 2s very well.And I have different valves.One has 2 x Mullard EF86 and 2 X GEC KT66 and the other one Mullard EF86 and an Osram Z729 and 2 Miniwatt KT66s.Both have Zeitek GZ32s.Will post some pics later.Ta
Going to check some voltages in the Quads tomorrow.At the mo the main prob is the Quad 22 pre amp.Prob one is the interconnects keep falling out the back.Also the 6 pin Jones connectors dont stay in the Quad 2s very well.And I have different valves.One has 2 x Mullard EF86 and 2 X GEC KT66 and the other one Mullard EF86 and an Osram Z729 and 2 Miniwatt KT66s.Both have Zeitek GZ32s.Will post some pics later.Ta
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If you can, get out these in a few time faulty connections. I did it and happy with results. I think old connectors does not bring anything good. Tubes... I use tesla ef806s and kt66 gold lion. Gz32 from ebay, at 20pounds or so. Detail, definition, realism for me, for my pocket, never will be able improve.
I have never heard GE kt66 and original EF86, but I do not think be a lot better than my combination (sure that there is guys with golden ears that can do it).
I think that the real key is the speaker. So, Esl57 is spectacular with a lot of amps (i had a wonderful elekit tu8600 and sound very good, but with quad2, better)
Best
I have never heard GE kt66 and original EF86, but I do not think be a lot better than my combination (sure that there is guys with golden ears that can do it).
I think that the real key is the speaker. So, Esl57 is spectacular with a lot of amps (i had a wonderful elekit tu8600 and sound very good, but with quad2, better)
Best
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No you don't. This is urban myth. They are perfectly stable without reproducing the shunt capacitance of the original C2/3, which any case was only 30pF, not 1nF. The KT66s already have that much in Cgk, you don't need to add to it.
Thanks for the info EJP.
I have measured all the resistors.
Quad ii No 1
R1 1.764M
R2 1.07M
R4 693R
R5 220K
R6 203K
R7 731K
R8 2K84
R9 708K
R10 85.09R
R11 85.4R
R12 193.4R
Quad No 2
R1 1.632M
R2 1.081M
R3 1.035M
R4 711R
R5 201K
R6 219K
R7 705K
R8 2K79
R9 712K
R10 83.6R
R11 84R
R12 184.6R
I have measured all the resistors.
Quad ii No 1
R1 1.764M
R2 1.07M
R4 693R
R5 220K
R6 203K
R7 731K
R8 2K84
R9 708K
R10 85.09R
R11 85.4R
R12 193.4R
Quad No 2
R1 1.632M
R2 1.081M
R3 1.035M
R4 711R
R5 201K
R6 219K
R7 705K
R8 2K79
R9 712K
R10 83.6R
R11 84R
R12 184.6R
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You can see that some of these are spot-on and some are way off. Contrary to what you have been advised above, I would replace all 12 resistors and also C1/2/3/5 if they are original. If they look new, don't replace them. If you haven't done Quad IIs before, do them one at a time so you retain a reference implementation to check against.
Use 0.5W 1% metal film for the resistors (5W for R12) and axial polyester for the capacitors, or PIO or PP if you must. Leave the oil-filled capacitors C4/6 alone unless one of them is s/c, which happens occasionally. When you replace the cathode circuit (R12/C5), mount the resistor well up into the breeze, and keep the capacitor well away from the resistor, as in the original. You don't want the resistor boiling the capacitor, and the resistor runs at 3.8W here. Use a large axial electro for the capacitor, and its correct value is 25uF, not 22uF. These are obtainable from Element14. 50V rating.
Use 0.5W 1% metal film for the resistors (5W for R12) and axial polyester for the capacitors, or PIO or PP if you must. Leave the oil-filled capacitors C4/6 alone unless one of them is s/c, which happens occasionally. When you replace the cathode circuit (R12/C5), mount the resistor well up into the breeze, and keep the capacitor well away from the resistor, as in the original. You don't want the resistor boiling the capacitor, and the resistor runs at 3.8W here. Use a large axial electro for the capacitor, and its correct value is 25uF, not 22uF. These are obtainable from Element14. 50V rating.
If you need to desolder components from the tag board to replace them, the tags on Quads seem to be very brittle - my vacuum solder-sucker knocked one off.
Measuring components in-situ isn't reliable if the components are in a circuit, and not terminated on a valve pin, for example. I get the feeling you are relishing the opportunity to update all the passive components, and that comes down to personal choice. My Quad IIs were ex-Swedish Radio, and they had replaced all the passives plus removed the valve rectifiers as part of their standard in-house maintenance procedures, and these amps are over 60 years old in some cases, so I also think pre-emptive maintenance is a good philosophy.
I did some minor changes, as described by Patrick Turner ...
Quad II Updates
I also used 6N1P tubes on one, instead of EF86, switched to 5B-255M tubes, making up an adaptor for the Loctal to Octal pins, so that I could keep on using NOS tubes.
Measuring components in-situ isn't reliable if the components are in a circuit, and not terminated on a valve pin, for example. I get the feeling you are relishing the opportunity to update all the passive components, and that comes down to personal choice. My Quad IIs were ex-Swedish Radio, and they had replaced all the passives plus removed the valve rectifiers as part of their standard in-house maintenance procedures, and these amps are over 60 years old in some cases, so I also think pre-emptive maintenance is a good philosophy.
I did some minor changes, as described by Patrick Turner ...
Quad II Updates
I also used 6N1P tubes on one, instead of EF86, switched to 5B-255M tubes, making up an adaptor for the Loctal to Octal pins, so that I could keep on using NOS tubes.
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You can use half-watt but check the voltage ratings.
Click is abnormal. Renovate the 22 next: four axial electros (same as C5 in the power amp), all the resistors that are attached to the triple capacitor (and no others), about 8 film caps, and the 1.5M screen resistors. Also the spark suppressors on the power switch.
Click is abnormal. Renovate the 22 next: four axial electros (same as C5 in the power amp), all the resistors that are attached to the triple capacitor (and no others), about 8 film caps, and the 1.5M screen resistors. Also the spark suppressors on the power switch.