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View Full Version : Amp upgrade: looking at an unusual solution....



Gazjam
11-08-2009, 10:53
Hey all..

Having recently "Caiminised" my 7520 Dac and been blown away by the improvements, I'm looking at other weaker areas of the chain that need to be upgraded for when funds allow.

My AE109 speakers...I love.
Big, ballsy very clear but not harsh in any way.
Would change them for something more natural sounding, more hear through clarity and soundstaging. More involvement I guess...

My Cambridge 640A amp......has developed a fault.
A dry joint on one of the channels is causing annoyance. Its fine from cold (when its not sounding its best) but when it warms up the dry joint problems arise causing the channel to switch off intermittantly.

I'm looking into getting it fixed, but having had reliability problems with CA kit before, I'm a bit pissed off its happened to my amp now as well.

Anyways, thats the background.

My next upgrade is my Amp, about, say, £500 or so to spend for something worthwhile over the Cambridge I've got just now.

Heres the thing, as the 7520 can act as a PRE AMP.....would I be better blowing my monkey (steady...!) on a Power Amp instead?

Would I get more for my money considering I've read how great the 7520 is as a preamp?

The only potential "gotcha" I guess is connecting it in to my system.

I use my 640A with my AV reciever driving the main channels using one of the line outputs, so if I was to use the power amp/Beresford combo I would need to be able to use the BDac as a Preamp AS WELL AS feed the two main L and R channels to the AV reciever for movies.

If this can be done it would be ideal, as I think a 2nd hand power amp with the Beresford as a Pre would be better sound quality that a £500 integrated.

Or am I talking nonsense and should change the speakers instead!


Ta for any help. :)

Gaz.

The Vinyl Adventure
11-08-2009, 11:09
im confused .. have you got that the right way round? do you play the squeeze box through the surround sound some times? if so the line outs on the dac will do that in the same way as the line outs on the cambridge

if you want to use the dac inbetween the ss amp and the the front channels then no its not possible as the beresford has no analogue input... although it could be done via the sqeeze box if that has a line in ... but you would be going digital - analoge - digital - analoge and im not sure that would treat the signal to well!!

unless you ss amp has a digital output??

The Vinyl Adventure
11-08-2009, 11:16
I use my 640A with my AV reciever driving the main channels using one of the line outputs, so if I was to use the power amp/Beresford combo I would need to be able to use the BDac as a Preamp AS WELL AS feed the two main L and R channels to the AV reciever for movies.


Gaz.

sorry .. i think i got it the wrong way round... does this mean you use the cambridge to power the front channels of the ss via the line outs of the ss amp

if so ignor the first part of my last post

Gazjam
11-08-2009, 12:50
Hey Hamish,

What I do is use a line out of my 640A amp into the Pre-In of the SS amp and set the 640A volume at 12 o'clock when watching films.

I dont know if you can use a power amp to power more than one "pre" so to speak.

If a power amp has more than one sets of outputs (i.e. power the 7520 AND the SS amp) that would be ideal.


Hope that makes sense, clear as mud?:)

The Vinyl Adventure
11-08-2009, 13:02
surly you mean pre-out of the ss amp into the input of the 640A - so the 640A powers the front speakers and the ss amp powers the rears and centre...

either way i know the situation you are describing, as i myself do it ...

you are unlikely to find a power amp with 2 inputs and a switch, as that, i think, technically makes it an integrated

you could put a simple 2 way switch box between the ss / beresford and the power amp.. i think stan was planning on building a input duplicator at one point? im not sure if anything came of it once he got his caiman plans underway you would have to ask him... or you could use a sony sb300 or sb 500 and add a bit of vintage to your system!!

either that or get a preamp ... or if you wannna keep it simple, a passive pre

The Vinyl Adventure
11-08-2009, 13:09
in fact, if you sought advice on connectors, wire, switch and case you might be able to find somone on here to wire up a simple 2 way switch box for you

Gazjam
11-08-2009, 14:20
thanks for that hamish me ole mucker.

gawd I need to do some reading!


That £500 integrated is sounding better all the time :)

Alex Nikitin
11-08-2009, 14:49
thanks for that hamish me ole mucker.

gawd I need to do some reading!


That £500 integrated is sounding better all the time :)

Hi Gaz,

Would you like to try a fully modified by the original designer (me, that's it :smoking:) Cambridge A3i? I am using one in my main system for last half a year and quite happy with it. I can make another for you, and it will cost you less than £200.

Alex

symon
11-08-2009, 15:27
Wow! It still amazes me how many people there are here who have such a deep involvement in designing and making hi-fi equipment, and who are so very generous with it!

Labarum
11-08-2009, 15:42
Gaz, try a quad 405 off eBay.

The 405-2 is the newer and better amp, but it may make little difference after the upgrade.

I bought a 405-2 and has it refurbished by 405man who sells on eBay - Search on his name.

You will end up with 120w per channel of sophisticated grunt.

A standard 405-2 should be selling for about £175 and (with postage) the rebuild will be under £100. You will have a box that will still be going in 20 years and sounds nearly as good as the current Quad 909.

405man does sell already refurbished 405s. (they go for more) You should be able to PM him via ebay or I can give you his email address.

Here's one (There are others if you search)

http://cgi.ebay.co.uk/VINTAGE-QUAD-405-MKII-AMPLIFIER-QUAD-405-2_W0QQitemZ320410855065QQcmdZViewItemQQptZUK_Audio TVElectronics_HomeAudioHiFi_Amplifiers?hash=item4a 99f9a699&_trksid=p3286.c0.m14

This one has been refurbished, but by whom and to what standard I don't know

http://cgi.ebay.co.uk/Vintage-Quad-405-2-Power-Amp-Very-Good_W0QQitemZ150365259487QQcmdZViewItemQQptZUK_Au dioTVElectronics_HomeAudioHiFi_Amplifiers?hash=ite m230277c6df&_trksid=p3286.c0.m14


Google "Quad 405" too for background reading

http://quad405.com/

http://www.hi-fi-insight.com/net-audio-modified-quad-405-2-amplifier.html

http://quadmodsusa.com/

Both my Standacs (7510 and Caiman) drive my 405 very well.

Gazjam
11-08-2009, 16:28
Brian the 405....

it looks as though its got two sets of outputs?
(4 phonos it looks like)

will that mean ir can drive my Caiman AND my AV amp front channels (obviously not at once!)


Thanks for the offer Alex, whats the advantages over the current crop of Azur amps, particularly my 640a?

(apart fromk not having a dry joint problem!)

thanks.

Alex Nikitin
11-08-2009, 16:48
Thanks for the offer Alex, whats the advantages over the current crop of Azur amps, particularly my 640a?

(apart fromk not having a dry joint problem!)

thanks.

Hi Gaz,

Cambridge A3i was a completely original design, the power amplifier circuit is unique and has nothing in common with either earlier or later Cambridge amps. Unfortunately, due to some poor quality parts and assembly problems it was not very reliable in the field. Occasionally I'm buying second-hand A3i amps from ebay and make these in what I would call a "designer's cut" version of A3i amplifier, replacing a number of parts, modifying the circuit in few places and fine-tuning the bias current. As a result modified A3i has extremely small distortion at low and mid frequencies (below -110 dB or 0.0003%) and very good sound too (sometimes these two things do not go together well ;) ). I think it can compete against any integrated amp of a similar power (2x50W into 8 Ohm) up to £1K, maybe more :smoking: .

Cheers

Alex

smithy
11-08-2009, 17:02
Find yourself a secondhand MC2 750,see what a big amp can do.If the slight fan noise doesnt bother you they are a bargain.

Labarum
11-08-2009, 17:05
Brian the 405....

it looks as though its got two sets of outputs?
(4 phonos it looks like)

will that mean ir can drive my Caiman AND my AV amp front channels (obviously not at once!)


All but the latest 405s had it's single input (L+R that is) on a 4 pin Din that connected from the pre-amp. The left and right outputs to the speakers were on 4 4mm banana plug sockets. (Two per loudspeaker, clearly.)

Most refurbs leave the 4 pin DIN where it is and parallel a pair of standard RCA phone sockets. You could loop from the DIN into you AV amp, but you might get some strange impedance effects. If you were having the amp ungraded maybe a resistive combiner could be added to the front end - what the quality cost would be I cannot say. The Quad power amps are rather more sensitive (330mV from memory) than modern power amps which have a standard line input of 2v (2000mV). That extra sensitivity would give you room for a few resistors. I had the input sensitivity of my Quad adjusted, which means if I choose I can run the Beresford into the Quad from its fixed outputs, and use the digital volume control on the Squeezebox. I don't, because my second digital input, the Virgin TV box has no volume control.

So yes, you could loop from the Quad to the AV amp, but might need some circuit mods to do it. But there is an easier way. Use the variable output of the Beresford to connect to the stereo power amp (whatever it is) and the Beresford fixed out put to connect to the AV amp which has its own volume control.

Spur07
11-08-2009, 18:01
I'm afraid I can only go with what I know - I haven't had the experience of listening to multiple products, valve amps, etc down the years like some of the other posters on this forum. So whether you pursue the pre/power or integrated route why not consider the Naim 'Olive' range if you want something clear, rhythmic and tight - or better still, check out the Avondale website. The Beresford is, after all, in its 'warts and all' conception very much akin to the 'Naim sound'.

Ali Tait
13-08-2009, 19:24
Hi Gaz,
If you would like to hear some valve amps,I'm not too far from you,being in Dunfermline.You'd be welcome to come over for a listen anytime.I have a WAD KEL 84 up here too,which would be my recommendation if you decided to go for a valve amp.