Dev's Amp Building exercise

Following on from this thread , Lee came around about 3 weeks ago to help me to build the amp (which BTW arrived with the power supply already built, thanks to Andy).

The first step was to lay out all the main components in the chassis and mark out the holes to be drilled/cut for tube sockets, output transformers, speaker terminals etc.



Drill out the holes for tube sockets


Cut out holes for output transformers


Fit transformers, speaker and RCA input sockets. Before any hawk-eye points out, I deliberately chose to reverse the red and black face plates for the speaker terminals to distinguish between left and red (I mean right).


Unfortunately the progress on this DIY project has been very slow due to other commitments and it doesn't seem like that is about to change with most of my next few weekends already booked up. Also my teacher/trainer Lee is not feeling very well at the moment and without him, I fear being electrocuted. Hopefully he's on the mend and will make a speedy recovery, not just because I need him you understand.

 

fantastc to see the progress!

sorry to hear lee's not been well and i would still like to pop over with those tapes bt i've been doing silly hours at work and not really been free at weekends

atb

john
a

 

Good work. Will be interested to hear how this fares against the Leak.

Lee, if you're reading this, sorry to hear you're not well. You should take a bit less exercise, it's very bad for you.

-- Ian

 

Good work there Dev.

When mounting the sockets, always think about the wiring underneath.
The circuit is this for those interested.



PS - Yep, still got that bronchial infection, have got through about a dozen Anadin Extra packets just to keep the temp down and headaches away. Can't stop coughing

 

Get better soon Lee, and keep taking the pills

 

There was some progress last weekend

Fit Tube Sockets




Like the jig?


Connecting up the heaters, grid resisters etc:-

 

You sure you're not rushing ahead too fast?

Looking good so far.

-- Ian

 

I didn't think so, but you're right, can't be too careful. I'll slow down a bit.

BTW, here's your amp providing sterling service (IMO) via the SRM10Bs.

 

Right, all done.

Now for the exciting part, turn it on. I'm afraid I'm just not brave enough, so this'll wait until Lee can come around again .

Anyway, this is what it looks like:-

 

Don't be such a wimp!

 

It's far more fundamental than that. I don't know what I'm doing. I really couldn't have built it without Lee's help.

Besides, being a wimp isn't such a bad thing, in fact it can be quite healthy.

 

Mea Culpa - I made some mistakes in my instructions so we didn't quite finish it.

Also we did actually switch it on and there must be something wrong with the CCS circuit as the fuse blew. What an expert eh???

 

Doesn't it glow well in the dark?



Doesn't sound bad either .

 

Couldn't believe we spent 4 hours trying to work out why it kept blowing fuses, looking for a short at any and every location , when all it appeared to be was that the 500milliamp fast blow couldn't take the switch on surge. Put a 1amp one in and bingo away it went. Didn't take too many voltages but those I did looked OK.

The CCS does have something wrong, I suspect it's just the voltage regulator, so we just stuck a 1.5k 3w (what I had in the box, should be about right) on the cathode of the 14F7 and she sings, and not a sign of hum.

Well done to Dev for constructing this. I tried to leave him to his own devices with it and just helped with interpreting the schematic, and the wiring. As Dev said, if he had to do it again he would do it differently and it would look neater.

 

nice one dev, looks great - bet it sounds good too... have to come over and hear it sometime
cheers


julian.

 

Result. How does it compare to the Leak then?

Must come over for a listen some time after xmas.

-- Ian

 

First impressions are good. I haven't yet had a chance to listen properly. I thought I'll save that for a bake off in the New Year. You are obviously all welcome to ridicule it and tell me what a waste of time it was. Meanwhile here's another picture (I'll take some better ones when I get a chance).:-

 

Hi Dev,

Good stuff!

Well done for self building. I hope to get back into more DIY in the new year. A phono stage project will be on the cards.

I have just looked at your link to photos of your system. I have noticed on top of your rack, a turntable! Getting into vinyl?

SCIDB

 

It's a cheapo TT Dean, I've had it for years for some old scratched vinyl I still have.

Regarding the amp, I enjoyed the experience. For £150 I wasn't expecting a lot to be honest, I wanted to see what it was like and as expected it has given me confidence to build another. Whether I do or not is another matter.

A couple of problems I've noticed with this amp.

1) It blew another fuse today , six inch nail anyone?
2) Slight clicking sometimes, like you get on vinyl.

Otherwise sounds good to me.

 

The Leak rules, mainly in the bass AFAICT.

You are very welcome to Ian.