diyAudio - Blog Entries
Go Back   Home > Forums > Blogs
Home Forums Rules Articles diyAudio Store Gallery Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Old

EEVblog #626 - Ceramic Capacitor Voltage Dependency

Posted 8th June 2014 at 06:59 AM by hollowman

The popular YouTube channel hosted by Dave L. Jones (Sidney, Australia bloke) just released his latest episode:

EEVblog #626 - Ceramic Capacitor Voltage Dependency

https://www.youtube.com/watch?v=TDDoi70cxw0

Of course some of DIYA's know-it-all will claim that this is not new info at all ... well if all you do DIY-audio and tweak and breadboard (and you've gotta lab bench in the little engineer's room ... so you can defecate-n-DIY at the same time) ... well, I suppose you really must know it ALL.
hollowman's Avatar
diyAudio Member
Posted in Uncategorized
Views 776 Comments 0 hollowman is offline
Old

DIY for Dummies?

Posted 5th June 2014 at 04:37 PM by hollowman
Updated 6th June 2014 at 07:07 AM by hollowman

For those of you not familiar with the USA book scene ... yellow-cover "...for Dummies" series has been one of the most successful (=popular/best-selling) book series in U.S. history.
Click the image to open in full size.

It was so popular that the style was copied by several other publishers' series including:
"...for Complete Idiots".
The term "idiot" or "Dummies" is used as hyperbole in claiming ensured comprehension. The approach relies on explaining a topic via very basic terminology.

But that is not subject of this Blog post ... so stay tuned for a bit... I've gotta take a dump...
Click the image to open in full size.
...and need a cup o' tea, love ...
Click the image to open in full size.

....OK,...
hollowman's Avatar
diyAudio Member
Posted in Uncategorized
Views 750 Comments 1 hollowman is offline
Old

Linsley Hood amp on Taobao

Posted 4th June 2014 at 06:27 AM by abraxalito

Looks like a bargain, around $120. Sorely tempted to get one to play with - what do you think ?
Attached Thumbnails
Click image for larger version

Name:	JLH.jpg
Views:	1031
Size:	58.8 KB
ID:	1301  
abraxalito's Avatar
diyAudio Member
Posted in Uncategorized
Views 1898 Comments 8 abraxalito is online now
Old

A Better Audio Comparison Tool

Posted 2nd June 2014 at 08:25 AM by fas42
Updated 14th July 2014 at 03:01 AM by fas42

I've mentioned a few times the difficulty in using the software tool, DiffMaker - and others have experienced similar issues. So, I'm thinking seriously about attempting to put together a "better" utility, something that will be more intelligent in correlating between different versions of sampled waveforms, wherever they came from. And it will be specifically aimed at trying to ferret out the deep down differences, not the obvious stuff like frequency response, phase shifts and the like - but rather the low level, detail variations that seem to be so important in subjective quality evaluation.

To give an idea of the "challenge", consider taking 2 recordings from 2 vinyl plays of a particular record. Having already seen what results, this is impossible for the likes of DiffMaker to handle - the constant speed variation between the 2 captures completely defeats it. But this what I would aim to be able to deal with, to synchronise in meaningful ways between...
Banned
Posted in Uncategorized
Views 839 Comments 5 fas42 is offline
Old

Cubist Subwoofer to go with Ikea bowl Speakers - just looks wrong!

Posted 1st June 2014 at 01:20 PM by googlyone
Updated 1st June 2014 at 01:24 PM by googlyone

A while back I built some Ikea bowl speakers using Vifa bassmids and tweeters. The performance came out very good indeed, but when you are dealing with a 5 odd inch driver, there will never be masses of bass.

A subwoofer was always on the cards.

Click image for larger version

Name:	IMG_1490_small.jpg
Views:	1392
Size:	661.2 KB
ID:	1298

Given the spherical speakers perched on the retro "rocket like" stands, I initially thought of doing a spherical subwoofer - but in the end concluded that while I could do this, I was looking at using fibreglass on a "fit-ball", placement in the room was looking to be a challenge.

So I chose to do the absolute opposite - and came up with an off the wall approach to a conventional sub.

Click image for larger version

Name:	IMG_1483.jpg
Views:	1284
Size:	739.6 KB
ID:	1296

Click image for larger version

Name:	IMG_1487.jpg
Views:	831
Size:	631.9 KB
ID:	1297

The idea was to move the implementation of a conventional sub well away from the "box with a driver stuck on the front".

I find it fascinating that...
diyAudio Member
Posted in Uncategorized
Views 1350 Comments 1 googlyone is offline
Old

Cheapo passive speakers breaking in

Posted 1st June 2014 at 07:02 AM by abraxalito
Updated 2nd June 2014 at 04:54 AM by abraxalito

A pair of these were delivered yesterday. At first I thought their bass sucked and the top end was too 'phasy' - it was only after a while I realized I'd connected them out of phase

Now they're wired up correctly on my TDA1521 amps, they're starting to come on-stream. I rate them as a bargain at the asking price of 228rmb (around $35).

After they've fully broken in I plan to explore what the lowest hanging fruit is by way of tweaks to the crossover....

Update1 - here's the XO, very simple 1st order. 250uH inductor on the bass (0.1ohm DCR, 6ohm bass/mid) and 1.5uF cap for the tweeter (8ohm). The NP cap for the tweeter has a rather high ESR (3ohms at 1kHz) so there might be some mileage in substituting this for a foil cap.

Plotting this arrangement on LTSpice gives a crossover frequency (if -6dB) around 7kHz which seems a little high. If we were to assume a -3dB crossover (because they're in quadrature for a 1st order) then it would...
Attached Thumbnails
Click image for larger version

Name:	Denon228s.jpg
Views:	157
Size:	12.4 KB
ID:	1295   Click image for larger version

Name:	DenonXO.JPG
Views:	214
Size:	678.4 KB
ID:	1299  
abraxalito's Avatar
diyAudio Member
Posted in Uncategorized
Views 605 Comments 6 abraxalito is online now
Old

Philosophy of boring DIY...

Posted 1st June 2014 at 06:02 AM by hollowman
Updated 1st June 2014 at 05:36 PM by hollowman

I've posted several topics on DIYA over the past few mos. All of them -- almost predictably now it seems -- dissolve into non-issues. I.e., not a lot of outside-the-box thinking ... methinks
Most of my "DIY" time is now on non-English sites like Player.ru and a few sites from Asia.
While the language barrier is large, and all I can do is read (just barely) using Google Translate, etc., -- and can't really post -- these obstacles seem worth the bennies. Namely, modding or building-from-scratch very inexpensive projects.
Many of the members of these non-English forums seem younger ... so maybe more fresh ideas, with more zest to experiment, and members seem to be genuinely cash-strapped (unlike the English-based forums) ... so the economies-of-scale are a lot bigger.
Comparatively, the English-speaking-forum "DIYers", being older, have their bank accounts and retirement incomes ... and, hence, a lot of drive/passion are diminished ......
hollowman's Avatar
diyAudio Member
Posted in Uncategorized
Views 834 Comments 2 hollowman is offline
Old

TDA8932 class D amp

Posted 27th May 2014 at 01:39 AM by abraxalito
Updated 16th June 2014 at 02:09 AM by abraxalito

One channel is completed - barring the off-board hexacap shunt - second channel under construction. Then for a comparison with the TDA1521s

Update1 - both channels running now, 160,000uF on each. Bass is tuneful but LF colourations noticeable on piano (Ashkenazy Diabelli Variations). Solution to this is simple - more caps

Update2 - an extra ring of caps around the original hexacaps now, so we're around 250,000uF. Bass is so much better than from the TPA3116 but the HF is more ragged, less transparency overall than the TPA3116. So I'll next try an outrageously decoupled implementation just to check I'm not limiting the chip with poor PSU hygiene....

Update3 - I have over 30 1206 10uF caps per side now as local decoupling - HF problems are slight. Makes me wonder if I use it only on the bass/mid and a TDA1521 for the tweeter duty we might reach audio nirvana.... Looking at the DS its easy to see why the HF's a bit of a mess - the PSRR is about...
Attached Thumbnails
Click image for larger version

Name:	P1010109.JPG
Views:	670
Size:	697.5 KB
ID:	1293   Click image for larger version

Name:	P1010110.JPG
Views:	780
Size:	719.9 KB
ID:	1294   Click image for larger version

Name:	extreme.jpg
Views:	604
Size:	67.8 KB
ID:	1300   Click image for larger version

Name:	P1010114.JPG
Views:	610
Size:	678.7 KB
ID:	1302   Click image for larger version

Name:	TDA8932taobao.jpg
Views:	647
Size:	63.8 KB
ID:	1306  

abraxalito's Avatar
diyAudio Member
Posted in Power chip amps
Views 2350 Comments 5 abraxalito is online now
Old

TDA1521 chip amps rock!

Posted 23rd May 2014 at 04:13 AM by abraxalito

Here's my prototype TDA1521 dual mono arrangement - two chips per channel in bridged/parallel, sat atop 400,000uF hexacaps. The neutrality has taken a while to get used to but I'm lovin' em....
Attached Thumbnails
Click image for larger version

Name:	P1010105.JPG
Views:	1157
Size:	711.2 KB
ID:	1292  
abraxalito's Avatar
diyAudio Member
Posted in Uncategorized
Views 1186 Comments 4 abraxalito is online now
Old

Technics SU-9070

Posted 20th May 2014 at 01:01 AM by rjm
Updated 20th May 2014 at 03:15 AM by rjm

The Technics SU-9070 is a 2U rack mount stereo preamplifier from 1977, matched to the SE-9060 amplifier. The preamp was sold as the SU-9070II in Japan.

The circuit is shown below, for educational purposes.

The power supply regulation is quite elegant, I hope to get to that in a future post. Here, just note that there are separate regulated lines for the MC stage, the input/VAS sections of the MM and line amps, and the output sections of the MM and line amps.
Attached Thumbnails
Click image for larger version

Name:	SU-9070 schematic edit.png
Views:	1477
Size:	328.0 KB
ID:	1290  
rjm's Avatar
rjm
diyAudio Member
Posted in The Lab
Views 1332 Comments 0 rjm is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 11:25 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2