BASIE pre-amp construction

Thought I'd drop a few notes on the construction of the 'Basie' pre-amp as I go along, for anyone thats interested.

The Basie is imported by DIY hifi supply, here' a link:

http://www.diyhifisupply.com/diy_kits/the_basie.html

It is a point to point wired, valve powered pre amp. The design includes star earthing and I believe the power supply is a valve rectified choke design.

Here's a pic.



One of the nice things about it is the audio asylum forum where the DIYers post tips on making it and their results of trying different resistors/valves/caps etc. http://www.audioasylum.com/forums/DIYHiFi/bbs.html

My kit includes the upgrades of kiwame resistors (below) improved output caps and cintinous cast copper wiring.



Later on, I may add a stepped attenuator - although the alps blue pot has a reputation of being one of the best 'standard' volume controls there is, so Im in too minds about that. If I do, it'll be the rather gorgeous goldpoint



I'll try and take some pictures of the insides as I go along, but its difficult because I havent got a digital camera.

Cheers
Chris

 

Is that a 5Y3GB rectifier tube?

I stuck one in my cornet phon stage, mainly for the coke bottle looks

Have you thought of useing 5N silver for the point to point?
.
I added a constant current supply on the phono amp by means of a mosfet, it was a classic drop down resistor circuit before. The mosfet addition has added a slightly more modern sound, seems slightly faster with a tighter sound.

 

Oh, Id forgotten to mention, Ive bought replacement valves too -

1 x E80cc (mullard NOS) - £20 yikes (for the cathode follower)
2 x E82cc (phillips RCA) - £7 each - more like it (left/right channels)

Im using the GZ32 equivelant provided, because Ive been told it is pretty good, despite being 'no name'

Chris

 

Here is a picture of the insides of one.. courtesy of someone else! hope they dont mind the link.

anyway, this is what they look like inside.




Hi Penance

Yes, I think the rectifier tube is the same, I think the code I quoted is just the Mullard stock number.

The kit came with continuous cast copper - which I generally prefer to the sound of to silver, I like the rounder sound of it - if that makes any sense.... mind you the great thing about the kit is theres loads of room so youve got space to change anything - I could even use shielded interconnect cable if I fancy it in the future... maybe just on the phono input, theres an idea...

I think the mosfet thing is a bit beyond me at the mo..sounds interesting though.

All the best
Chris

 

Hi mate
yup the copper thing makes sense

i have a schematic of the mosfet CC if you would like to see it, tho i would suggest building standard first and then try later

let me know how it sounds

 

well, the kit is complete!

...except for a couple of resistors which werent part of the kit, and testing.

Cant tell you what it sounds like yet, but I can say that the construction time was approximately 12-15 hours, and I would describe it as logical, easy to follow, but also lengthy and requiring skill with a soldering iron.

Cant wait to fire it up and hear it !


Chris

 

nice going mate, i wanna hear your full report

 

Well done Chris.

There is a sequence to switching on for the first time by BTW if you don't have a variac.

With no valves in
With just the Rectifier in
With all of the valves in

At each step you should do some measuring of voltages, if the test points and values have been provided.

All the best

 

Nah, just switch it on and see if you have any hair left when it fires up. If you do, it's working.

Good work Chris. I've had a WAD kit for about a year, and I've still barely started it.

-- Ian

 

oh well..

Ive completely finished it now (100%) and it doesnt work!! hahahaha thats so funny!

Anyway, Im taking it next week to a valve bloke I know who will get it going and he wont charge me much I dont think...

Still, I learnt something by doing it myself.. wonder where I went wrong? d'oh!


Chris

 

thats cheating !half the fun of biy is trying to get the dam things workin.

 

Time to cheat I think hippy!! - Im fumbling around in the dark with 400v capacitors, and I think it might be the best £30 I ever spend !!

NB Just noticed my GZ32 rectifier has a whole in the bottom (wonder if thats why it doesnt work!!!??!!).. but still, I didnt get the right voltage readings over the valve bases so its off to the expert it goes...

A new GZ32 will be £15-£45 depending on type OUCH

Chris

 

Since its excess to capacity, why not use it to power some speakers for the computer? - you could maybe rob PB of his crown of best sounding PC?? (seconds away, round 1, ding ding!)


Chris

 

Chris

Shame you won't have a go at problem solving, but I must admit it can be daunting.

The GZ32 is probably OK. It just has the centre pin missing. This make me wonder whether you have actually plugged it in the wrong way. Mind you if you haven't you would know as sending 300v up the heaters is not pretty.

 

u sure about the GZ32 lee?

the tube is no longer a vacuum - you can waggle a wire inside the glass... surely that means its stuffed?

I dont know that much about valves really...!


Chris

 

Ah, you didn't say that before, just that it had a hole in the middle.

Sounds stuffed to me

 

reckon you're right!

Have just bought a cheapy russian equivelant GZ32 for £7, going to stuff it in and either have success or a loud BANG! in my kitchen..

fingers crossed.... here's hoping it doesnt cause catastrophe...

 

Well - it didnt work with the cheap GZ32. £4 +vat and postage !!

Its at the menders getting fixed, should be back in about 3 weeks.

Anyone had much experience of tube rolling with GZ32's or other rectifier valves?

Im in 2 minds about keeping the cheapy GZ32 in or buying a posh Philips/mullard for it on its return.

Im well familiar with changing output valves and the differences in sound you get there - but Ive never had an amp with a GZ32 rectifier or similar in before, so I dont know if its an area where you get much sonic difference from tube rolling.

Anyone?


NB Ive read the stuff on DIY hifi supply on the subject, but am interested to hear from tubed people on here...


Chris

 

Hi Chris,
my experiance of rolling with rectifier tubes was that there can be a change in sonics, very subtle and maybe a change but not neccessarily an improvement.
I found rolling the pre-amp tubes (12AX7/AY7) to have a much more beneficial effect and more noticeable. Im sure youve tried this before tho.
I found an old NOS Mullard 12AU7 had the nicest effect

 

Well

The man has fixed my pre-amp - apparently my soldering was rubbish, and I even missed out a couple of very essential wires for the heater supply!!! hehehe (I think thats hysterical)

Well, I still enjoyed it.!

He's measured it, and it is apparently showing very good results on a distortion meter and frequency generator/oscilloscope etc.

Should be picking it up mid-week, and will let everyone know what its like

Chris