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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 18th Jan 2008, 4:09 pm   #21
Cformat
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Default Re: Quad 2 Valve power amp questions

Ah yes, the ST25 was always a serious alternative to the Quad 2 and probably better in some ways if not ‘philosophically’ with the 57s.

And I take your point about trying to preserve the KT66s and lengthen life generally as prices seem to have entered the stratosphere lately. (I think ebay is a larf) For my part happily I have a few spare valves (bought from MO Valve for £15 each I recall) and a complete and un-modified amp for spares if an when needed (paid £25 for that one - long time ago).

Using a PC seriously is interesting: excellent convenience but very alien when you (like us) have been brought up on record decks, tape recorders and FM tuners. I have 3 audio systems at the moment, the main one (but not used very often) has the Quad speakers and amps together with a sprinkling of other fairly classic baubles. The 2nd set up has a pair of LS3/5As, a Leak Stereo 20 and sundry other bits, but again is hardly ever used. While the 3rd set up which is a laptop based headphone rig is on all day every day. Unfortunately I spend rather a lot of time these days at the hospital, and for these times I use a DAP into a good pair of phones via a headphone amp. I have to say once I got used to making hard disk recordings, converting them to Mp3s, and swapping files between machines, the old ways of the tape recorder seemed not just obsolete but pretty stone age by comparison. And while I was a bit ’you can’t beat analogue’ etc for a long time, to be perfectly honest I find Mp3 quite good enough for serious listening, provided of course it was encoded with a high (ish) bit rate. Tape is long dead, the CD is on its last legs and in a very few years the only source of music will be the computer.

Cue violin.

As regards live Jazz concerts, there seems to be some sort of evil conspiracy afoot to strangle any hope of a clean live sound. Most musicians these days seem to have forgotten how adequately loud acoustic instruments are, and the stuff all sorts of nasty PA kit around the stage. The end result is that even a modest home system will be considerably better than the live event. Well at least as far as the sound goes, perhaps losing out on atmosphere though.

Cheers
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Old 18th Jan 2008, 4:38 pm   #22
ppppenguin
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Default Re: Quad 2 Valve power amp questions

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Originally Posted by Cformat View Post
As regards live Jazz concerts, there seems to be some sort of evil conspiracy afoot to strangle any hope of a clean live sound. Most musicians these days seem to have forgotten how adequately loud acoustic instruments are, and the stuff all sorts of nasty PA kit around the stage. The end result is that even a modest home system will be considerably better than the live event. Well at least as far as the sound goes, perhaps losing out on atmosphere though.
Hear hear! Not just jazz either. Especially when the performance is in a venue that is already acoustically efficient, such as the Royal Festival Hall. The sound balancers are probably deaf, having spent too much time at rock gigs where louder=better.

As for protecting a Quad II, if you can't fuse the centre tap of the secondary then you can put a fuse in the cathode of the rectifier. I had a pair of Quad II long before they became highly collectable. My experience is that they are an incredibly tolerant design. I ran them with KT66, EL37 and even EL34 (strap g3 to cathode) with no apparent change in performance. I did of course measure the cathode current to ensure nothing nasty was happening and I think I may have changed the cathode resistor value slightly on occasion. I think of the pitiful amount I sold them for in about 1981 though it was a lot more than I paid for them
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Old 18th Jan 2008, 5:40 pm   #23
mastermanx2001
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Default Re: Quad 2 Valve power amp questions

Hi Cformat (like the name) and anyone interested, we may be going a little off topic here, The moderator may object, but all this stuff relates to Quad and British equipment. I have to confess that I am a bit of a speaker nut and yes also have LS3/5a (Chartwell 15 Ohm) bought for £90 many years ago from a friend who had them new. My Quad IIs+22+FM1+decoder was bought even longer ago for £10 from a friend who changed to 33/303/FM3. I also have home built LS3/5a clones, JR149, LS7, LS3/6, Spendor BC1, BC2, B&W DM1, DM2a, DM3, DM4, DM5, various old Celestion models and more, much more! It all started in the late 60s going down to the Rogers Factory (Jim Rogers) was a family friend and I used to be given some of his cast offs. With advent of ebay, a few years ago I could find some of the stuff that I could not afford years before. I have a Williamson built by my uncle at the Rogers factory in the early days (PX25 output valves). I avoided PCs up to about 8 years ago (possibly a wise decision) I would recommend trying one as the head of a hi fi. Beware, most PCs usually have good sound, but dont take it for granted, I use a Creatve Soundblaster card, even the cheapest of them seems very good. As mentioned the sound card feeds the power amps directly. The Quad 33/303 0r 44/303 alway sounded reasonable, but I only recently discovered how good the 303 is when connected without these pre amps. Same applies to the Quad II and Radford STA 25.

I agree, high bitrate MP3s are fine, but recently discovered that there is another format (Ha Ha!) Flac files. This is suposed to be even better, and I have to agree it is good. I listen to a lot of internet radio and that is improving almost daily (I prefer it to DAB tuner). I afraid the BBC is way behind in this internet radio, audio quality is no good. I'm afraid my FM tuner, preamp, reel to reel, casette, record deck are redundant.


Best regards, Paul
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Old 18th Jan 2008, 5:44 pm   #24
mastermanx2001
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Default Re: Quad 2 Valve power amp questions

Hi Ppppenguin

Thanks for this, seems a good idea will probably carry out this mod.

Regards, Paul


Quote:
Originally Posted by ppppenguin View Post
Hear hear! Not just jazz either. Especially when the performance is in a venue that is already acoustically efficient, such as the Royal Festival Hall. The sound balancers are probably deaf, having spent too much time at rock gigs where louder=better.

As for protecting a Quad II, if you can't fuse the centre tap of the secondary then you can put a fuse in the cathode of the rectifier. I had a pair of Quad II long before they became highly collectable. My experience is that they are an incredibly tolerant design. I ran them with KT66, EL37 and even EL34 (strap g3 to cathode) with no apparent change in performance. I did of course measure the cathode current to ensure nothing nasty was happening and I think I may have changed the cathode resistor value slightly on occasion. I think of the pitiful amount I sold them for in about 1981 though it was a lot more than I paid for them
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Old 19th Jan 2008, 12:04 am   #25
GrimJosef
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Default Re: Quad 2 Valve power amp questions

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Originally Posted by Herald1360 View Post
The 6L6 does take less heater current but it's a lower power valve too. I suspect to use it, ideally you would need to rebias the output stage and probably consider lowering the screen voltage ...
I agree Chris. 6L6-family and KT66-family valves will often work in the same equipment unless the HT supply is really high, when the ratings of some of the 6L6s can be greatly exceeded. Things are not so bad in the famously gentle-on-its-valves Quad II, but there are "Spinal Tap" type guitar amps which take no prisoners.

And there have always been cases of manufacturers pushing the labelling limits. The picture on the left shows a KT66. The picture on the right, in my opinion, shows a sheep in wolf's clothing.

Caveat emptor !

Cheers,

GJ
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