You are here

D.I.Y. amp

Customising, building or repairing your own gear? Need help with acoustic treatment or soundproofing? Ask away…

Re: D.I.Y. amp

Postby Folderol » Sat Mar 26, 2016 12:19 am

blinddrew wrote:I've read all of this thread and found it fascinating whilst simultaneously not understanding a word.
Oh...


I like the pictures.
Well that's nice :)
User avatar
Folderol
Jedi Poster
Posts: 8768
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: D.I.Y. amp

Postby Martin Walker » Sun Mar 27, 2016 4:45 pm

blinddrew wrote:I like the pictures.

I see quite a few people standing for hours in newsagents who claim the same thing :roll:


Martin
User avatar
Martin Walker
Moderator
Posts: 14246
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: D.I.Y. amp

Postby zenguitar » Mon Mar 28, 2016 12:54 am

Martin Walker wrote:
blinddrew wrote:I like the pictures.

I see quite a few people standing for hours in newsagents who claim the same thing Image


Martin

Oi know where you live Martin...

It was either Farmers' Weekly or Guns & Ammo they were browsing ;)

Andy :beamup:
User avatar
zenguitar
Moderator
Posts: 9208
Joined: Thu Dec 05, 2002 1:00 am
Location: Devon
When you see a fork in the road, take it.
Yogi Berra

Re: D.I.Y. amp

Postby Folderol » Mon Mar 28, 2016 2:56 am

... and there was I thinking you'd come to comment on the latest update :frown:

Oh well {sigh}
User avatar
Folderol
Jedi Poster
Posts: 8768
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: D.I.Y. amp

Postby Martin Walker » Mon Mar 28, 2016 3:56 pm

Folderol wrote:Hi Martin,

Well it's nice to know someone reads back over this missive ;)

The new transformer is a toroidal one, and now I have the input isolators I use a 'hard' ground. The hum level from the speakers is now much lower than the mechanical hum from the transformer!

This is excellent news - hum levels are generally far lower with toroidal transformers (due to their weaker radiated magnetic field) than EI-frame designs.

OK Folderol?


Martin
User avatar
Martin Walker
Moderator
Posts: 14246
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: D.I.Y. amp

Postby Trevor Johnson » Mon Mar 28, 2016 4:19 pm

Another advantage of toroidal mains transformers is not having to source terminal covers for the primary and secondary winding terminals.
Trevor Johnson
Regular
Posts: 206
Joined: Sat May 15, 2010 12:00 am

Re: D.I.Y. amp

Postby Folderol » Mon Mar 28, 2016 4:47 pm

Thank you Martin :)

I'd have gone for a toroid at the start, had the input transformers been available when I started (and the info on how to wire them), but for safety you have to have a hard earth on the secondary. Isolation grade ones for low voltage are as rare as rocking-horse poo. Split bobins are pretty common on EI format, as are electrostatic shielded ones.
User avatar
Folderol
Jedi Poster
Posts: 8768
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: D.I.Y. amp

Postby Folderol » Wed Mar 01, 2017 5:48 pm

Ho Hum, back again.
As noted 'elsewhere', I now have a new proper Log pot for the volume control, and very nice it is too. However, I also wanted to try out a couple of mods, and need the excuse to make myself drag the amp into the workshop.

So, a quick health check before doing anything.
A visual inspection revealed no signs of stress anywhere - no hot-spot discolouration, and the sniff test confirms it's beginning to develop that 'aged electronics' aroma :)
Bias current, initially set at 200mA was within 10mA on all three channels, and DC offset was less than 50mV so I left all of these alone, and just fitted the new volume control - all done in about 15 minutes.

However, this made one of the mods I was considering moot - changing the input stage to a long-tailed pair to improve DC offset stability - a case of "If it ain't broke, don't fix it".

The other mod, was to insert an additional resistor in the driver stage to make overload conditions more even, and hopefully get rid of the DC shift that occurs under these conditions. Well, I tried that on just the RH channel, and wound LH & RH up together with a mono signal and... it made absolutely no difference at all!

Clearly, I've misunderstood how it is developing, so I put things back as they were. However, I don't like mysteries, so I'll probably mock up an equivalent circuit at work sometime to see if I can find out what's actually happening.

Meanwhile...
I still haven't actually run it at full power - my near-fields were starting to wimp out :(
I still haven't got a proper front panel on it {sigh}

P.S.
Three and a half years and still counting :roll:
User avatar
Folderol
Jedi Poster
Posts: 8768
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: D.I.Y. amp

Postby Hugh Robjohns » Wed Mar 01, 2017 6:35 pm

:D
User avatar
Hugh Robjohns
Moderator
Posts: 24375
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: D.I.Y. amp

Postby Sahib » Wed Mar 08, 2017 8:25 pm

Weldone with the amp.

I would happily make the front panel for you. Below two are examples of custom stuff that I do. Drop me a mail at info@totalaudiocontrol.com

Dual tube compressor.
Image

1u tube guitar pre.
Image
Sahib
Poster
Posts: 18
Joined: Sat May 28, 2016 12:00 am
Location: Glasgow

Re: D.I.Y. amp

Postby Martin Walker » Thu Mar 09, 2017 10:39 pm

Sahib wrote:Weldone with the amp.

I would happily make the front panel for you. Below two are examples of custom stuff that I do.

Hi Sahib!

We don't normally allow people to advertise their own wares on the SOS Forums, as otherwise they would be awash with adverts :headbang:

However, I've created a few of my own one-off front panels (and therefore know just how hard they can be to design and fabricate to a professional standard).

I suspect therefore that others will agree with me that in this case (pun intended) your 'boutique ' front panel making service may well be very welcome to other DIYers.

So, unless anyone else objects I'll leave your post in place.

Lovely work by the way! 8-)


Martin
User avatar
Martin Walker
Moderator
Posts: 14246
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: D.I.Y. amp

Postby Folderol » Fri Mar 10, 2017 10:40 am

The idea, of getting a panel made had previously occurred to me but there are a number of problems with that.

First of all, the positions of controls etc. is quite tight. It was difficult to arrange them so that they looked reasonably evenly spaced yet had enough room behind for all the gubbins. - especially between the display and logic screening and the filter controls to the right. Things like display window alignment and control mountings have to be exact so it would hardly be a 5 minute job, which of course translates directly to cost.

Also, up to now, I've done absolutely everything myself - short of making the components! I do know a method of making the panel just as I want, but it's a case of getting the materials, then getting my brain in gear to actually get on with it (instead of more enjoyable things).

Finally, the amp is in daily use, and I think I'd have serious withdrawal symptoms if I was without it for any time now and had to temporarily use a {cough} inferior {cough} unit.
User avatar
Folderol
Jedi Poster
Posts: 8768
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: D.I.Y. amp

Postby Sahib » Fri Mar 10, 2017 3:19 pm

I deeply apologise for this, I absolutely did not know the rules. Please do delete that post.

However, just to say that the sum involved in such activity is so small that it often does not register as a commercial activity, but nevertheless it is. So my deep apologies again.

I am still happy to help and what you may consider my fee could be donated to the forum.
Sahib
Poster
Posts: 18
Joined: Sat May 28, 2016 12:00 am
Location: Glasgow

Re: D.I.Y. amp

Postby Martin Walker » Fri Mar 10, 2017 4:23 pm

Sahib wrote:I deeply apologise for this, I absolutely did not know the rules. Please do delete that post.

No worries Sahib!

As I said above, I do realise that yours wasn't a 'hard sell', and was also specifically intended for fellow DIYers, so I'm happy to leave your post in place.

Having said that, like Folderol I do know the amount of work that has to be done in designing and fabricating a good-looking front panel (I recently made one for a modded synth, and the front panel took me longer to make that all the synth modifications :headbang: )


Martin
User avatar
Martin Walker
Moderator
Posts: 14246
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: D.I.Y. amp

Postby Dynamic Mike » Sat Mar 11, 2017 1:25 am

Sahib wrote:I deeply apologise for this, I absolutely did not know the rules. Please do delete that post.

However, just to say that the sum involved in such activity is so small that it often does not register as a commercial activity, but nevertheless it is. So my deep apologies again.

I am still happy to help and what you may consider my fee could be donated to the forum.
So far as I'm aware it's fine to link to a commercial site under your signature (like Martin has done for his CD's) just not in free text. Incidentally I'd rather you didn't because when I looked up the Total Audio Control website (which incidentally links back to SOS!) I wanted everything. If you had a hand in designing the panels on the site, nice work, I think some of them are gorgeous.
Dynamic Mike
Frequent Poster (Level2)
Posts: 3091
Joined: Sun Dec 31, 2006 1:00 am
Guitars are like partners. You know within 10 seconds of picking one up whether or not it's a keeper. 

Re: D.I.Y. amp

Postby Sahib » Sat Mar 11, 2017 11:58 pm

Thank you Martin.

Mike,

Thank you for your comments too. Indeed I do the front panel designs myself.
Sahib
Poster
Posts: 18
Joined: Sat May 28, 2016 12:00 am
Location: Glasgow

Re: D.I.Y. amp

Postby Martin Walker » Sun Mar 12, 2017 5:21 pm

Dynamic Mike wrote:So far as I'm aware it's fine to link to a commercial site under your signature (like Martin has done for his CD's) just not in free text. Incidentally I'd rather you didn't because when I looked up the Total Audio Control website (which incidentally links back to SOS!) I wanted everything. If you had a hand in designing the panels on the site, nice work, I think some of them are gorgeous.

Just so, they are indeed gorgeous!

I've just discovered your web site as well Sahib, and as Dynamic Mike mentions, you really ought to put a link to it in your forum signature (as I do, and which is quite acceptable - a link to follow if anyone is interested in finding out more about a poster, without actually appearing to 'tout for business' :mrgreen: )


Martin
User avatar
Martin Walker
Moderator
Posts: 14246
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: D.I.Y. amp

Postby Folderol » Sun Mar 12, 2017 9:41 pm

I must agree, these are very nice work, but, well, you know :shh:
User avatar
Folderol
Jedi Poster
Posts: 8768
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: D.I.Y. amp

Postby Folderol » Fri Jun 15, 2018 5:41 pm

After a very enjoyable week in Berlin, with 4 days of the Linux Audio Conference in the middle, I got home late, tired but happy.

That was until a dropped my bags in the front room, and immediately saw the amp display was lit, along with a familiar buzz from the speakers. Wait! What? My amp doesn't buzz.

The display was showing everything normal so, had being left on for a week done some damage? Dried the main caps out or something. However, these are (rather expensive) honking great cans, with a very high ripple capability, so did it mean something else was wrong, either with the amp, or the sound card.

While worrying over the possibilities, I absently put the guitar back on its stand as it seemed to have fallen off, at which point the buzz dramatically reduced - to my great relief. It seems I'd left it plugged in :roll:

I shut down and went to bed.

Today was my first chance to have a play again, and everything seems hunky-dory... but.

I still haven't got a proper front panel.

I still haven't run it at full power.
User avatar
Folderol
Jedi Poster
Posts: 8768
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: D.I.Y. amp

Postby blinddrew » Fri Jun 15, 2018 7:14 pm

Have you still not got a front plate sorted out? :headbang: ;)
User avatar
blinddrew
Jedi Poster
Posts: 7914
Joined: Sun Jul 05, 2015 12:00 am
Location: York
Ignore the post count, I have no idea what I'm doing...

PreviousNext

Who is online

Users browsing this forum: No registered users