graham67

Quadies Unite!

Recommended Posts

As for the 405, perhaps a Net-Audio 'full' upgrade - anyone had this done?

Paul

Hi paul, i think the answer to this question of which is better may depends a lot on the speakers being used. I have a lovely Quad serviced late 405-2 (the one in the first posting) and another virtually identical 405-2 but with the full Net Audio 405-3 mods.

Into a pair of 70's tannoy HPDs, IMO with a Quad 34 pre-amp, the stock 405-2 is definately better sounding then the Net Audio amp, with a more appealing flowing sound that is less dry and more energetic. Just realised the above statement needs to be clarified, However I have found these era Tannoys don't seem to favour transistor amps with a vice like grip, something a bit looser seems to suit them better.

(18/8 Of course my comments may not apply with a different pre-amp, perhaps it is just a synergy thing with the Quad 34.)

Which is one reason why I think the 405-2 makes a good match. It is not a high current amp, indeed it limits the current deliberately. If I remember right, the early 405-1 was about 4-5 amps, the later 405-2 was around double this. And so the damping factor of 80 is not very high for a 100w transistor amp.

Whereas the NA 405-3 uses much higher rated 30A transistors and the damping factor is over 200. So a 405-3 will drive speakers that a 405-2 will struggle with.

However in my experience it is all down to matching as the 405-2 can better suit older speakers that were designed for less powerful amps. As a trial, I will shortly be refitting the stock but serviced 405-2 boards with the Net Audio Dual Mono PSU which effectively doubles the capacitance of the power supply. I have tried this combination setup before to seeming good effect though my system has changed a fair bit since last I tried. I will post an update once I have given it a good listen.

I certainly agree with the comment above that the condition is important, I had an old 405-1 with bulging PSU caps and it sounded pretty awful until the caps were changed. A late 405-2 in particular can sound very nice if matched sympathetically.

If you travel to Surrey, please PM and you can come listen for yourself to my quad of Quads!

Share this post


Link to post
Share on other sites
Hi paul, i think the answer to this question of which is better may depends a lot on the speakers being used. I have a lovely Quad serviced late 405-2 (the one in the first posting) and another virtually identical 405-2 but with the full Net Audio 405-3 mods.

Into a pair of 70's tannoy HPDs, IMO the stock 405-2 is definately better sounding then the Net Audio amp, with a more appealing flowing sound that is less dry and more energetic. However I have found these era Tannoys don't seem to favour transistor amps with a vice like grip, something a bit looser seems to suit them better.

Which is one reason why I think the 405-2 makes a good match. It is not a high current amp, indeed it limits the current deliberately. If I remember right, the early 405-1 was about 4-5 amps, the later 405-2 was around double this. And so the damping factor of 80 is not very high for a 100w transistor amp.

Whereas the NA 405-3 uses much higher rated 30A transistors and the damping factor is over 200. So a 405-3 will drive speakers that a 405-2 will struggle with.

However in my experience it is all down to matching as the 405-2 can better suit older speakers that were designed for less powerful amps. As a trial, I will shortly be refitting the stock but serviced 405-2 boards with the Net Audio Dual Mono PSU which effectively doubles the capacitance of the power supply. I have tried this combination setup before to seeming good effect though my system has changed a fair bit since last I tried. I will post an update once I have given it a good listen.

I certainly agree with the comment above that the condition is important, I had an old 405-1 with bulging PSU caps and it sounded pretty awful until the caps were changed. A late 405-2 in particular can sound very nice if matched sympathetically.

If you travel to Surrey, please PM and you can come listen for yourself to my quad of Quads!

Problem I have is that I don't really 'need' the 405 at all as I'm happy with (and have been since 2008) my current set-up in the 'Shed' & in the main house we have a 34, FM4, 306 - the 34 has just been posted to IAG for repair and the early 34 I picked up recently is doing a fine job as a temporary stand in. Of the 2 FM4's that came with the 34, 306 & 405 one is perhaps viable to be professionally repaired (I've done as much as I can) & the 306 seems absolutely fine. Just had another look inside the 405 and along with the bulging main caps some of the other bits on the output boards are a bit furry(?)

p><p><img src=[/img]

p><p><img src=[/img]

Couple of things I didn't like about the Net-Audio upgrade was not the fact they remove the wiring to the DIN socket, but that it isn't blanked off (I know a minor point as I can easily get a grommet myself) and that it looses the multi-voltage functionality but again the selector is still available - again IMO should be removed and blanked off but all that's quite minor. As to the sound, well I think it is universally recognised that the early 405 wasn't really that good and the mk2 was really a step up in quality.

As for the speaker I'd use with the Quad, I have a really nice pair of low efficiency Minimax's from the same era as the 405. I've never been able get rid of and they continually surprise everyone who has heard them, they've also been in the family from new & I find them superbly musical. These are the front ported ones with a Japanese Coral bass/mid unit and a Philips soft dome tweeter.

Paul

Share this post


Link to post
Share on other sites
Guest

I wouldn't say you need to go as far as a net audio upgrade with that, though. An hour with a soldering iron to change all the caps and it will go on happily for another 36 years. I also don't see why net audio couldn't preserve the DIN connector and voltage selector for you on request.

The significant difference between the 405 and the 405-2 was that the current limiting circuit was refined to more closely track the output device's safe operating area on the 405-2, making it a bit less prone to kicking in when presented with a difficult load - so the "step up" in quality will only be evident if your speakers are a difficult load and you're driving them hard enough to get current limiting, IMHO.

Share this post


Link to post
Share on other sites
I wouldn't say you need to go as far as a net audio upgrade with that, though. An hour with a soldering iron to change all the caps and it will go on happily for another 36 years. I also don't see why net audio couldn't preserve the DIN connector and voltage selector for you on request.

The significant difference between the 405 and the 405-2 was that the current limiting circuit was refined to more closely track the output device's safe operating area on the 405-2, making it a bit less prone to kicking in when presented with a difficult load - so the "step up" in quality will only be evident if your speakers are a difficult load and you're driving them hard enough to get current limiting, IMHO.

I agree with above, this looks like an ideal candidate to go to Quad for a service and new BHC PSU caps and board caps. They also will fit new high good quality banana posts and RCA sockets (and there is no reason the RCA cannot be kept in parallel with the DIN if required).

You could even get Quad to fit new boards to upgrade the amp to 405-2 spec, last time I spoke to them they still sell new 405-2 boards!

A couple of years back I was quoted a cost of around 200 for all these mods and you effectively get a new amp.

Graham.

Share this post


Link to post
Share on other sites
I agree with above, this looks like an ideal candidate to go to Quad for a service and new BHC PSU caps and board caps. They also will fit new high good quality banana posts and RCA sockets (and there is no reason the RCA cannot be kept in parallel with the DIN if required).

You could even get Quad to fit new boards to upgrade the amp to 405-2 spec, last time I spoke to them they still sell new 405-2 boards!

A couple of years back I was quoted a cost of around 200 for all these mods and you effectively get a new amp.

Graham.

I'd was already erring on the option of just getting it serviced by IAG (but not too sure based on some of the above statements I'd bother getting it changed to a 405-2 spec) as I think I'd like to keep it as close to original spec as possible, I'll see how I feel when the 34 gets returned in a few weeks. Reason I'd like to retain the DIN socket is that the (spare) 34 Pre I have is an early DIN version and TBH I have no issue with this type of connector. Anyway as I seem to have a bit of a Quad amplification glut at the moment, don't need to be in a particular hurry to decide which way to go.

Paul

Share this post


Link to post
Share on other sites
I think I'd like to keep it as close to original spec as possible

Paul

Hi Paul, an over abundence of Quads seems to be a common affliction......

But in case you are worried about originality a lot of 405-1s were upgraded to 405-2 spec in the eighties. Quad even used to and still do (as best I know) change the nameplate to 405-2. This may explain why you can see 405-2 spec amps with serial numbers that show they started life as a 405-1.

In fact the very last 405-1s were actually fitted with early 405-2 12565 Issue 5 boards!

Share this post


Link to post
Share on other sites
What do people think is better. The 306 or the 405-2 ?

There's no strong consensus. The 306 is a less interesting design but I slightly preferred it - others will tell you different. The 606 onward were much better than either.

Share this post


Link to post
Share on other sites

I have two 303 amps which I was using vertically biamped but now sitting in their boxes unused for some time. I guess they will be going in the classifieds.

Share this post


Link to post
Share on other sites

Just a few photos of my modded Quad set up.

My modded Quad 22 feeding my Linn Intek it was in a poor state when I got it so it has been totally redesigned.

FinishedQuad22_01.jpg

I've revamped the back panel.

FinishedQuad22_02.jpg

Modified Quad II with power supply modifications.

QuadIIAmps05.jpg

My modded Quad 22 bought up to date I just use it as line preamp with the ECC83 in the first stage and mosfet source followers in the output stage to feed the amp.

Some photos of the mods.

Cap05.jpg

New balance control.

AfterBalanceControl01.jpg

Separate PSU.

PowerSupply02.jpg

Volume control replaced with an Alps pot also a view of the mosfet output stage.

MosfetBuffer02b.jpg

Sharif.

Share this post


Link to post
Share on other sites

I picked up a 405-2 in the summer and tried it with a Tisbury passive pre-amp and a modded Caiman DAC running from a laptop and it was... ok... but I loved the design and couldn't let it go (the super wammer that I bought it from had let me borrow it first).

Fairly recently though I finished making a DCB1 buffer for it (for those who don't know it's a Nelson Pass-inspired B1 buffer with a shunt regulated power supply) and it really started to sing between a PiDAC, the DCB1 and some Frugal Horn speakers. Still not quite right in the bass though and with a small pop through the speakers when turning it on and a very subtle hum. What I perceive as the bass deficiencies (a bit loose and sort of hinted at more than cleanly delivered) have been handled pretty well by crossing the Quad and Frugals over at either 80 or 100Hz and using a BK sub but I've heard Steve Jay's commercial electricbeach Frugals deliver amazing bass so I'm pretty sure the speakers weren't the whole problem.

The amp was described as modded by Keith Snook and Keith confirmed this - "modded to DCD Mod 3" but he also pointed out that the person who brought it to him asked him not to touch the PSU, presumably intending to ask Keith at a later date to add his dual mono design. So the amp section has been modded and otherwise reconditioned to last for decades but the PSU caps are original and must be 30 odd years old, crazy really.

Firmly on the DIY path by now but not up to Keith's standard I opted for the Net Audio dual mono PSU and that should arrive today. I'll let you know how I get on with it.

Share this post


Link to post
Share on other sites

I'm looking at getting a new quad power amp. I'm currently using a 303 with a 34 pre. I thought I'd pick up a 306 so it matches the 34 pre. I have seen that Quad 99 power amps are quite plentiful and wondered if I should be looking at one of these instead or are the difference between the 306 and 99 minimal. Opinions appreciated.

Share this post


Link to post
Share on other sites
I'm looking at getting a new quad power amp. I'm currently using a 303 with a 34 pre. I thought I'd pick up a 306 so it matches the 34 pre. I have seen that Quad 99 power amps are quite plentiful and wondered if I should be looking at one of these instead or are the difference between the 306 and 99 minimal. Opinions appreciated.

I doubt there's a minimal difference between the 306 and 99. The 99 is a great little power amp but if you can stretch to the 909 it's a lot better.

Share this post


Link to post
Share on other sites

The 909 is out of my price range at the moment. I guess it's a choice of aesthetics (the 306 matches the pre and tuner) or potential improved sound the 99.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.