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Old 18th Apr 2024, 8:47 pm   #1
BrettCrame
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Default Request for options for original Quad II's and Quad 22

Be Gentle! I have a pair of quad II's and a quad 22 pre-amp which look all original with no upgrades or replaced parts. They are working, but do not sound the best. I have changed the output taps as per Keith Snook's website to enable use with my floorstanding 8ohm speakers. I have the original ESL57's, but unfortunately I don't have the space for them, even though I love the sound!
I will be recapping and checking components on the II's, hopefully this will bring them back to their best but I'm a little hesitant to do this on the 22.
Here's the questions I would like your opinions on;
1, Should I attempt the works on the 22? or should I send away for a service to quad.
2, Should I ditch the 22 and look at another pre-amp that will offer easier options for CD's, DAC's connections etc (I would love to have the full original system working, but If there are much better sound options I need to consider it)
3, What Pre-amps would you recommend, not budget types but not the ridiculous priced units I have seen mentioned elsewhere. I understand there is an output voltage that needs to be compatible for the II's to work at their best, how does that match up with modern pre-amps?
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Old 18th Apr 2024, 8:56 pm   #2
paulsherwin
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Default Re: Request for options for original Quad II's and Quad 22

If these are unrestored, they will need a full refurbishment before they will work well. That's a specialist job if you want to preserve the value.
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Old 19th Apr 2024, 8:30 am   #3
BrettCrame
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Default Re: Request for options for original Quad II's and Quad 22

Thanks for the reply Paul, I will be refurbishing the II's myself, full strip back to shell etc etc. Im capable of that, the 22 is another matter, I really dont want to spend time on it if the general consensus is that a better pre-amp will benefit me more in terms of sound, connection options and less service hassle. On the other hand I have a donor 22 also which I can steal from as I think I have at least one pot that is in need of replacement. Really, just looking for a group consensus on best option going forward.
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Old 19th Apr 2024, 9:19 am   #4
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Default Re: Request for options for original Quad II's and Quad 22

So they basically work but badly.
On the QII's you mainly need to change the 0.1uF coupling caps. Any decent modern caps will be fine. Strictly speaking you should also add 18pF caps between the signal (control grid, grid 1) and ground, to simulate the original metal cases being clamped to ground. Even if you don't bother, they usually work Ok.
With the 22 pres you need to change all the black Wima caps as they also go electrically leaky. After that you should have good working amps. Keep an eye on the power transformers for undue temperature rises and also keep an eye on the KT66's for any excessive blue glowing which could indicate ingassing.
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Old 19th Apr 2024, 10:01 am   #5
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Default Re: Request for options for original Quad II's and Quad 22

Valve preamps of that era were all the weak points in their systems. In order to keep the number of valves down they wound up lacking in gain and circuits like Baxandall tone controls ran out of gain at the boost end. They were also fairly noisy. Once silicon transistors had become common and cheap, preamps improved quite significantly.

To stick with the Quad theme, how about tracking down a Quad 44 ?

I've got a long term project here, an amazing far-over-the-top preamp, a Revox B252.

David
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Old 19th Apr 2024, 10:18 am   #6
Gabe001
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Default Re: Request for options for original Quad II's and Quad 22

I use my valve amps with a raspberry pi 3 + Allo boss DAC HAT loaded with LMS software (volumio or moode work well too, but LMS is the best). It sounds more complicated than it looks and the output is high enough do drive the valve amp directly.

This allows me to use my phone/tablet to stream digital music from my NAS, Spotify, YouTube, BBC sounds, tune-in radio and Qobuz to any of the valve amps via the raspberry pi and a simple RCA cable. It works very well and I can listen to pretty much anything I like, including radio and podcasts. In addition, the raspberry pi is Bluetooth capable which opens a whole new host of connections - e.g I sometimes use Bluetooth to stream movie audio to my valve amp.

This would be my recommendation for a reasonably priced pre amp for your quads. There are Chinese Allo Boss clones which work well (tried and tested) and a second hand raspberry pi 3 should be reasonably priced at £35, or so

KR
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Last edited by Gabe001; 19th Apr 2024 at 10:37 am.
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Old 19th Apr 2024, 5:20 pm   #7
Richardgr
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Default Re: Request for options for original Quad II's and Quad 22

Seconding Gabriel's suggestion. My solution is even simpler (though not better), just a bluetooth receiver plugged in with RCA plugs.

However this will leave you with a dilemma, unless you are able to source an RCA adaptor for the Jones plugs that are the inputs to the Quads. The alternative is some minor surgery to add an RCA socket on each amp.

If you get this solution for just using the amps sorted then you might be pleasantly surprised at the sound at that point, but there are some parts in the Quads that have a finite life span or are impacted by operating conditions, i.e. some caps and possibly resistors too.

What speakers are you using? I use bookshelf Canton's with mine, not especially sensitive, and my pair perform very well with those.
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Old 19th Apr 2024, 8:31 pm   #8
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Default Re: Request for options for original Quad II's and Quad 22

I'm assuming that someone who seems to have had Quad IIs, 22, and ESL57s for some time and likes the sound of them, might not be quick to jump into lossily-coded formats, and may be looking for a classic preamp.

CD players typically give enough output voltage that only a volume pot is really needed between a player and the power amps. This is minimalist and can reasonably be assumed to introduce no real degradation, but misses out on tone-shaping and switching facilities. Wanting to play vinyl/shellac discs would also force a preamp.

The Quad 33 was OK for its era, but their later models got a bit better as they learned that they didn't have to be stingy with the transistor count and that there were some opamps which were useable. The Quad 44 came an appreciable time after the 33, but it did represent a significant step onwards. It also retains much of the configurability for various sources.

There are other makes of preamps worthy of consideration, but I would definitely go solid-state myself. Another thought is that when Quad put the Quad II back into production, what preamp did they expect to pair them with? The 22 was out of production.

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Old 19th Apr 2024, 9:48 pm   #9
Gabe001
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Default Re: Request for options for original Quad II's and Quad 22

The OP did ask for a preamp with 'CD/DAC connections' in post 1, which pretty much excludes any of the classic pre-amps and almost everything manufactured prior to 2020. At least that was my interpretation of the original request, and of course I could be mistaken.

If digital music streaming is the OPs preferred music source, I still stand by my suggestion. I'm a firm believer of open source products as opposed to proprietary software which ends up unsupported after a couple of years, and my proposition is fairly inexpensive in as much as modern pre-amps and DAC streamers go.

On the other hand, if analogue music sources are preferred , that's a totally different ball game. A classic pre amp would be the way forward, and the first decision is to either go valve or solid state.

No reason why you can't have a classic pre amp and a separate digital system. I play both vinyl and digital music files and enjoy both.

Last edited by Gabe001; 19th Apr 2024 at 9:56 pm.
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Old 19th Apr 2024, 11:20 pm   #10
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Default Re: Request for options for original Quad II's and Quad 22

I think the thing to remember here is that this is a Vintage Radio/TV/Audio forum.
There's no issue suggesting sources such as streaming, I suspect a good percentage of the forum members use such sources, (I know I do) but their implementation perhaps belongs elsewhere.

This has been discussed in the moderator "staff room".

Cheers

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Old 20th Apr 2024, 12:45 am   #11
Ted Kendall
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Default Re: Request for options for original Quad II's and Quad 22

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Originally Posted by Radio Wrangler View Post
The Quad 44 came an appreciable time after the 33, but it did represent a significant step onwards. It also retains much of the configurability for various sources.
...and of course has a specific 1.6v output available for connection to Quad IIs!
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Old 20th Apr 2024, 1:52 pm   #12
Leon Crampin
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Default Re: Request for options for original Quad II's and Quad 22

The 44 unfortunately has proved to be far less reliable than other units such as the 33, due to its increased complexity coupled with Quad's disinterest in component quality.
The 33 has a 4 way plug in board for pu input equalisation, one side of which is uncommitted. By the addition of, I think 2 resistors per channel fitted to the board, it's possible to reconfigure the disc input to accept a 1V input from a cd player with a level response, such that the "disc" button operates correctly and the levels match those of the tuner inputs.
It was a very long time ago that I made this mod to a 33 but I remember it as being very simple to execute. I think the first 2 stages were bypassed in order to lower the gain. The actual 33 mainframe was unmodified - other than Rifaectomy to limit smoking....

Leon.
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Old 20th Apr 2024, 2:58 pm   #13
Richardgr
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Default Re: Request for options for original Quad II's and Quad 22

Quote:
Originally Posted by Radio Wrangler View Post
I'm assuming that someone who seems to have had Quad IIs, 22, and ESL57s for some time and likes the sound of them, might not be quick to jump into lossily-coded formats, and may be looking for a classic preamp.

...
Hi David, my suggestion was an idea to get the amplifiers up and running and give them the opportunity to be sorted out, independently of sourcing a preamp.

The OP will need to decide at some point how to attach another preamp using RCA plugs, or whether to persist with the 22 preamp and the Jones plugs.

Most modern digital sources would not need to be amplified for the Quads anyway, so unless they have a record player as well, or they need to control the volume, there is not a lot of need for a preamplifier.

There are RCA to Jones plugs adaptors, so probably that is the least intrusive solution.

Cheers, Richard
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Old 20th Apr 2024, 5:55 pm   #14
Craig Sawyers
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Default Re: Request for options for original Quad II's and Quad 22

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I Another thought is that when Quad put the Quad II back into production, what preamp did they expect to pair them with? The 22 was out of production.
David
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This https://www.quad-hifi.co.uk/qc-twenty-four/ . Valved. About a grand.

There is also a dedicated phono stage, solid state https://www.quad-hifi.co.uk/qc-twenty-four-p/ . Again about a grand.

Another from the Quad stable is the Artera Pre. That also includes the tilt control not seen since the 44 and 34. https://www.quad-hifi.co.uk/artera-pre/ . About - no surprise - a grand.

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Old 21st Apr 2024, 10:09 am   #15
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Default Re: Request for options for original Quad II's and Quad 22

Hello,

Keep thinking I should chime in…

I know the OP is looking for a ‘modern’ replacement for the Quad 22 preamplifier, but I feel the following ramblings could be of some interest.

A while back I sorted a Quad 22 system for a friend and to get the preamplifier up to specification, I replaced all the film capacitors, not just the coupling, bypass and the capacitor on the switch contacts, but also the capacitors in the tone controls and filter. The Polyester and similar capacitors were OK. There were a few rouge carbon comp resistors. Replacing the triple can electrolytic was a pain – I had three axial capacitors spread throughout the preamplifier! Thankfully the pots including the volume were still serviceable.

He now uses the system with separate ‘modern’ phono amplifier going into the Tuner 1 input [directly to the volume control] as this bypasses the first EF86 preamplifier stage and just uses the second ECC83 preamplifier stage and tone control and filter circuit. This gives the tone control and filter circuitry without the limitations associated with the first EF86 preamplifier.

The power amplifier work was as already described. I remember Phil Taylor saying about the 18pF a good few years ago.

Way, way back I did knock-up a preamplifier with a 1.4V output from a standard line input level based around a Wolfson WM8816 [MAS6116] and a high-performance FET OP amp to drive a pair of Quad IIs – but that’s a whole different story from a previous life.

Also, In the past to run pair of Quad IIs with lower-level preamplifier I’ve used a 10-15dB preamplifier between the Quad II amplifiers and preamplifier.

Personally, a limitation of the Quad 44 pre is the 4066 CMOS input switches. When I had a 44/405 system in the workshop, I ended up swapping the 44 for a 33 preamplifier, sadly that doesn’t have enough gain to drive the Quad IIs. The Quad 33 isn’t without its own limitations though.

Finally, some pro gear uses 1.4V levels to drive power amplifiers, so there may be some leads [no pun intended] there.

I think Craig is on the right track. I saw the Quad gear at the Bristol hi-fi show, sadly I can’t remember anything about the preamplifiers being used with them!

…Anyway, back to an Errant Rogers Cadet III I’m sorting out to do talk at social event end of May!

Regards
Terry.
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Old 21st Apr 2024, 2:08 pm   #16
toprepairman
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Default Re: Request for options for original Quad II's and Quad 22

The social event could be interesting, where would that be?
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Old 21st Apr 2024, 6:16 pm   #17
Leon Crampin
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Default Re: Request for options for original Quad II's and Quad 22

I spent a long time assessing 4066 devices which were needed for a military automotive job. The design of this device is such that it is easy to turn on a parasitic substrate diode in use, which then severely degrades the device.

The fix was very careful circuit design, and component testing which, in the end resulted in only one supplier being approved for this job.

In the 44, Quad fails my assessment on both counts. Despite limitations, the 33 is a better unit. My preference is for a unit that works reasonably well all the time rather than....

Leon.
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Old 21st Apr 2024, 6:58 pm   #18
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Default Re: Request for options for original Quad II's and Quad 22

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which then severely degrades the device.
Turns on a parasitic thyristor shorting the power supply direct to the ground (substrate ) pin. There is nothing to limit the current taken other than metallisation, bondwires, power supply. Kapow! Phut!

This is a common hazard in CMOS devices if inputs can stray just a Vbe outside the power and ground voltages.

It is a risk which has to be carefully considered even with proper, intentional analogue switch ICs. With logic ICs pressed into analogue service, you have to be borderline paranoid about it.

David
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Old 28th Apr 2024, 12:56 pm   #19
BrettCrame
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Default Re: Request for options for original Quad II's and Quad 22

Hi All,
OP here, thanks for all the info and advice, lots to take on board and process. Just to clear a few things up, I primarily use vinyl (a Technics sl1300 and a phono-stage) so this is definitely a requirement. I would like to have other digital input options, even a built in streamer would be desirable. Thinking more on this I believe a remote control and tone control is also essential which I think rules out the new quad pre-amps. It's a difficult one to try and solve, maybe recondition of the original 22 is the best solution and I will have to live with getting off my bum to adjust the volume!
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Old 29th Apr 2024, 12:06 pm   #20
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Default Re: Request for options for original Quad II's and Quad 22

I use either an Audiolab or NAD preamp with my Quad IIs which works well.

For streaming I've recently bought a Wiim Pro which I'm pleased with. It has an excellent DAC and gives good results with Spotify or Tidal (and internet radio) and it also supports Chromecast. I'm using a redundant tablet as a controller.

Won't sound as nice as your Technics though!
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