anyone familiar with valve amps?

DonMaico said:
Took the opportunity to email audio synthesis and have to say they were most helpful.i appaers I would need a RIAA phono stage to go with their passive amp in oder to bump up the sinal to line level.Dont think the Croft would need such a thing.

Hi Don....if you're simply running straight CD into the pre,then an RIAA eq'd phono stage would be unneccesary,but obviously for vinyl,you would need it....what did you have in mind?
 
alexs2 I have an alphason sonata t/t for which I would needf a phono stage . Although I dont use it so much these days I still like to have it for occasional viny use.l must admit I feel somewhat seduced by the Passion Ultimate/ phono. do you think it would work well with a valve amp? Whats the difference between gain and volume?On my A I its one and the same thing
 
Sadly the passion sells for considerably more than the £ 800 you mentioned- £ 1295, and the passion with phono -- a cool £ 2190. think if I spent that kind of money my wife would have a fit :nono:
 
I understand now....the Passion Ultimate and Phono combination will not be cheap,but the quality will be superb,and I personally couldnt see any problems in using it with a valve amp....you'd be looking at about £1300 each,and that will be quite a mismatch in price/quality terms with your speakers....on a cheaper note,the little Project Tube Box offers phono preamp for MC/MM at a very reasonable price and good quality also.
For some years I used my AS passive with a triamped active Krell/Linn system,as the attenuator between the CD and the active crossovers on that system,and also as the input to a pair of Tube Technology Genesis valve power amps.
As you know,I'm currently using it to control the level into an Earmax valve H/phone amp,and it's more than transparent enough for that sort of use.

Essentially gain can be used as another word for volume in many contexts,with low gain= low volume and vice versa.....the situation changes when describing whether or not a pre amp increases the level of an input by adding gain(or voltage) to the signal by amplifying it,but for most intents and purposes it can be thought of as the same thing.
 
I see from your equipment that you are very much into the high end. I f money was no object then I would certainly change my speakers to something like Lowther accolades 2 or Loth hornloaded. Think I would stick with valves though maybe an output tranformerless Croft power amp and a suitable pre. I also quite like the Loth T/T. Any way thats all hypothetical .Cant say I am all that unhappy with my HB! sand look forward to doing some of the tweaking londondecca suggested.I'd only change them if i could afford a hornloaded design
 
I see they hold their value very well . there is a used passion 8 for sale at £ 1100
 
DonMaico said:
I see from your equipment that you are very much into the high end. I f money was no object then I would certainly change my speakers to something like Lowther accolades 2 or Loth hornloaded. Think I would stick with valves though maybe an output tranformerless Croft power amp and a suitable pre. I also quite like the Loth T/T. Any way thats all hypothetical .Cant say I am all that unhappy with my HB! sand look forward to doing some of the tweaking londondecca suggested.I'd only change them if i could afford a hornloaded design

I wish!....more the product of years of collecting and telling the wife that it cost 10% of the actual(god help me if she ever finds out!).
The combination of low output valve amps and horns can be stunning in terms of dynamics,and some of the 300B and 845/211 designs I've heard are just lovely in the midrange,but for me anyway,don't offer the sort of bass power and control I wanted....hence the room heating Krells.
I'd certainly give the Project Tube Box a look though,as the looks are not dissimilar to AS's boxes,and the quality is good as well.
Your choice of the Passion Ultimate though,is never going to disappoint,as you'll be able to use it for years without ever having to consider upgrading.
In terms of sound quality though,your Leaks as you know are superb,and still very much sought after....I've got an old pair of Quad IIs which I use for late night low level listening with the AS,and they still have many qualities which rival some very expensive current amps.
 
The price I quoted was for the Passion,not the Ultimate,and some of these do crop up from time to time on the used listings,if that's any help.
 
Alexs2 i am not very good at telling porkies as i am bedevilled by a concience.I hav etoi do things by stealth> When my wife went on a riding holiday to Wyoming I took the opportunity to buy my AV equipment. upon her return she grumbled but having spent a fortune in the US she couldnt say much.
I will consider the AS but the Croft Vitale woud seem to represent far better value.They also do the Epoch for about £ 800( I think)
you probably wouldnt recognise( well you would but you know what I mean) my Leak as it is quite different to an original . I has this 4" tube where the rectifier was with a plastic cap on top which is connected to the underside. I am told its a supposed to be a regulator valve.
 
Hi again,Don....glad to find someone else who resorts to similar methods to finance his hobby!

The Croft Vitale is certainly very good value in sonic terms,it's just that the AS is superbly finished and constructed and does just what it says on the box,with NO colourations etc at all.

What you're describing on your Leaks sounds like a change to the type of rectifier being used,with a top-cap type valve now being used.....there are loads of different rectifiers around,and even some mods that use solid-state rectifiers to replace tubes,although most people reckon that tube regulation is the best.

If you're interested in the valve types and descriptions,the following sites may be of use...

www.tubecollector.org
www.r-type.org

Both are very extensive resources on valve types and equivalents.
 
Ty alexs2 dont want to delve too deep or else I shall end up confused . when one hasnt a technical mind it can be incredibly difficult ot understand theories especially when they are spouted by the likes of Hi Fi News and some dealers I have come across. its like they come from a different planet. Mindboggling.
Read this article that said what mattered, as far as transistor amps go,was the amperage output not wattage as the more amps the better the bass and the more it can work didficult loads( 4 ohms , 2ohms etc). the wattage is only important as far as the specs go when it clearly doubles as the load increases. this is why I bought the Hk which althoiugh it doesnt double there is a considerable percentage increase. Any I talked to some else and thay said " its not as simple as that" So there we are I am confused as ever. :D

Mind you i lke the look of that AS . Just asked them to send me a list of dealers :thumbsup:
 
DonMaico said:
Mindboggling.
Read this article that said what mattered, as far as transistor amps go,was the amperage output not wattage as the more amps the better the bass and the more it can work didficult loads( 4 ohms , 2ohms etc). the wattage is only important as far as the specs go when it clearly doubles as the load increases. this is why I bought the Hk which althoiugh it doesnt double there is a considerable percentage increase. Any I talked to some else and thay said " its not as simple as that" So there we are I am confused as ever. :D

Mind you i lke the look of that AS . Just asked them to send me a list of dealers :thumbsup:

LOL,I do understand what you mean...the characteristics of transistor amps are very different from valve amps in terms of output and load tolerance.
SET valve amps offer stunning midrange quality,but are entirely dependent on the combination of their output impedance(generally high)and their output transformers,plus the load offered by the speakers.
Push-Pull amps(most of them,incl your Leaks and my Quads)are much less load dependent,but both these and SET's have generally limited capabilities in terms of current delivery,but it doesnt stop them sounding good!....it merely means they may sound a bit soggy if partnered with a really difficult load.
A really heavily engineered Class A transistor amp,like an old Krell or some of the newer models etc,will continue to deliver increasing current and power into ever decreasing loads,and the old KMAs would deliver anything up to +/- 50 amps into 1 ohm loads with no problems...from mine that equates to 800w into 1ohm,but also very useful with nasty speaker loads.....my Quads sound lovely with the N805s,but have very limited bass drive without a sub doing most of the work,even at low levels,whereas one old Krell ad saw a KSA100 being used to run an electric jackhammer.

As for the AS....buy and enjoy,you know you want it... :D
 
Which is why its important to use efficient speakers with maximum sensitivity of about 90 db right?My kefs are supposed to be 90 db but sound cr#p with leak whereas the Hb!s sound fine to me????( just realised i am talking about something completey different - efficiency not Loads). I wonder how a pair of Rogers LS35 a would sound like? 15 ohms but only about 83 dbs- flat I guess!

Any way I notice transistor amp specs rarely mention amperage or for that matter wattage into 4 and 2 ohms - just 8 ohms. What are they hiding? They also tend be fairly lightweight suggesting small transformers which I guess would make them cheaper.the chap who said " its not as simple as that" was a dealer and I am guessing he thought I was the kind of guy who couldnt afford an amp with large transformer delivering plenty of amperage so he just shrugged my question off. :smoke:
 
DonMaico said:
Which is why its important to use efficient speakers with maximum sensitivity of about 90 db right?My kefs are supposed to be 90 db but sound cr#p with leak whereas the Hb!s sound fine to me????( just realised i am talking about something completey different - efficiency not Loads). I wonder how a pair of Rogers LS35 a would sound like? 15 ohms but only about 83 dbs- flat I guess!

Any way I notice transistor amp specs rarely mention amperage or for that matter wattage into 4 and 2 ohms - just 8 ohms. What are they hiding? They also tend be fairly lightweight suggesting small transformers which I guess would make them cheaper.the chap who said " its not as simple as that" was a dealer and I am guessing he thought I was the kind of guy who couldnt afford an amp with large transformer delivering plenty of amperage so he just shrugged my question off. :smoke:

With lower output amps,valve or transistor,high sensitivity speakers are essential,and a lot of the horn designs run at over 96dB/W,whereas things like my N805s are allegedly 88dB/W but very current hungry designs.
As far as a valve amp is concerned,with proper output transformer matching,you will get the same output into 8 or 15 ohms if the taps are set correctly,and the LS3/5s would sound lovely,but you wont get high levels out of them...you wouldnt anyway,as they werent designed for that.

Transistor amps and output into lower loads.....always a contentious area,but you have to consider the cost of incorporating a power supply capable of delivering increasing output into decreasing loads.
It isn't an issue with most valve amps as it just doesnt happen,but in the early 80s a lot of manufacturers went a bit mad with claims of power output etc,and along came a wonderful old speaker called the Apogee Scintilla,which sounded superb(a ribbon speaker with an impedance of 1 ohm(!)),and about the only thing that would drive it was the Krell KSA100,with a 2kW transformer,and around about 150,000uF capacitance per channel.
The thing weighed a good 70kgs(I know as I had one)and thats the reason that most lesser designs are a bit cagey about decreasing load impedance.
It's not quite as simple as a bigger transformer,but includes either very large supply capacitors,or switch-mode supplies a la Linn or Chord,and none of those things are cheap to engineer properly,to be fair.
If you look at the transformers and power supplies in a lot of AV amps,they are just about able to sustain rated output into 8 ohms,never mind below that,although there are many decent exceptions.
 
so from your first para I deduce that for high levels high efficiency is required. As long as I set the taps to 15 0hms a rogers LS35a should work well?Funnily enough they were set there when I first bought the leak and it was suggested to me to leave them there.
on the transistors side I thought it had something to with cost. just thought of transformres as they appear to be the biggest and heaviest components. So thats why there are so many 8 ohms speakers around- easier top drive and requiring more modest amps? Just wish dealesr were a bit more honest about it.

Re AS naughty naughty you shouldnt tempt me :devil:
 
DonMaico said:
so from your first para I deduce that for high levels high efficiency is required. As long as I set the taps to 15 0hms a rogers LS35a should work well?Funnily enough they were set there when I first bought the leak and it was suggested to me to leave them there.
on the transistors side I thought it had something to with cost. just thought of transformres as they appear to be the biggest and heaviest components. So thats why there are so many 8 ohms speakers around- easier top drive and requiring more modest amps? Just wish dealesr were a bit more honest about it.

Re AS naughty naughty you shouldnt tempt me :devil:

With valve amps that have multiple transformer taps,it's very important that the correct tap is used relative to the speaker impedance,or power output may be diminished,and distortion potentially increased.
Thus if the LS3/5A's are 15 ohm models,then the 15 ohm tap should be used.

Power transformers and power supply components do add up as some of the highest cost items in transistor amps(and valve amps too of course,especially with SET amps,where good output transformer design is essential and costly),but in general terms,8 ohms is a relatively easy load for most amps,and power supply costs can be kept to reasonable levels.
Fully regulated designs capable of delivering constant voltage and increasing current into low loads are heavy and expensive(unless considering switch-mode supplies,in which case just expensive!).
A really good example is another of my favourites,the Levinson 20.5,a mono Class A design with fully regulated supplies and nominally 100W into 8 ohms,which weighed about 80kgs per channel,although that was outweighed easily by the Krell KSA250 at nearly 150kgs if I remember(but you're looking at over 1000W into 2 ohms there),and over 2kW of heat.
 
Funny that dealer I bought leak from should sety taps at 15 ohms.Her knew which speakers I had?? Maybe I should change them. aAl thes year and i hadnt noticed any distortion?? maybe my ears are shot! LOL

so why buy spewakers that have difficult loads ? Do they deliver better bass perhaps if partnered with suitable amp.Rember listening to an arcam amp thro a pair of celestions and they sounded dreadful sort of flat and lifeless. I am guessing they were 2 or 4 ohm speakers. needing much more power to get them going.
 
DonMaico said:
Funny that dealer I bought leak from should sety taps at 15 ohms.Her knew which speakers I had?? Maybe I should change them. aAl thes year and i hadnt noticed any distortion?? maybe my ears are shot! LOL

so why buy spewakers that have difficult loads ? Do they deliver better bass perhaps if partnered with suitable amp.Rember listening to an arcam amp thro a pair of celestions and they sounded dreadful sort of flat and lifeless. I am guessing they were 2 or 4 ohm speakers. needing much more power to get them going.

Very possibly was making an inspired guess!....

The reason behind some speakers being difficult to drive is a combination of driver/cabinet design,and the crossover design needed to deliver a relatively flat response.
I don't recall any Celestions being less than 6 ohm loads,but there are many speakers that need a good deal of power to produce a sound with some life...my N805's could be said to be in that category,in that they do sound best with a really hefty amp behind them,and they certainly ran a TAG 100x5 amp into clipping very easily.
Tailoring the crossover characteristics to get good extension from small boxes has long been an art,and often results in complex loads at low frequencies,exactly where a lot of amps struggle to deliver current and control.
Many of the speakers I've had have been loads like that(Linn,B&W etc),but there's no doubt about the bass extension and clarity that can be had...the Wilson System 5,6 and 7 speakers are also excellent examples in the high end.
 
so i guess the idea is if buying a transistor amp go for one that is really heavy, expensive and which delivers a substantial increase of wattage into 4 ohms and 2 0hms ( double?). What sort of price point should start looking at and which makes??Think I can discount Levinson and Chord. I'm only thinking if I everv decide to change my AV amp :)
 
Well...there's plenty of good AV amps,(and your HK is a good one,capable of decent power delivery into 4ohms),but if you were looking to receivers,then Denon and Pioneer seem to have little problem with 4 ohm loads,and the world of multichannel amps is huge...Rotel are good in the lower price ranges,and there are plenty around used also.
If I was looking for a good,relatively cheap multichannel amp thats also good for stereo,the Rotel range would be very high on my list.
 
What a lovely thread, especially when you own Croft super micro, AS Passion, croft modified Leak Stereo 20, KEF, Tags....

From my experience the croft pre is best with RIAA, I modded mine to feed the AS Passion directly and then to Stereo 20. This is the best combination. Croft as a pre is pretty decent but not in the class of the AS, even when pots are changed.
 
The Beekeeper said:
What a lovely thread, especially when you own Croft super micro, AS Passion, croft modified Leak Stereo 20, KEF, Tags....

From my experience the croft pre is best with RIAA, I modded mine to feed the AS Passion directly and then to Stereo 20. This is the best combination. Croft as a pre is pretty decent but not in the class of the AS, even when pots are changed.

Good to see you again....and nice to have another endorsement for AS....nothing will match one in terms of pots,unless you're using Vishay resistors in the pots....arent they lovely!
 
Dead pc at home, and hardly ever at work so time is limited at the moment, no more than that :) Still here, still causing trouble :)

yup Vishay are KING :smashin:
 
The Beekeeper said:
What a lovely thread, especially when you own Croft super micro, AS Passion, croft modified Leak Stereo 20, KEF, Tags....

From my experience the croft pre is best with RIAA, I modded mine to feed the AS Passion directly and then to Stereo 20. This is the best combination. Croft as a pre is pretty decent but not in the class of the AS, even when pots are changed.


Croft is tends to favour analogue reproduction so that figures. Never tought about using a croft as an RIAA . What sort of mods did you make?

Can I say thanks to all the postings in here - it has certainly given me something to think about :thumbsup: :thumbsup:
 

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