My latest project - 60w per channel amp (just pics) - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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
Reply
 
Thread Tools Search this Thread
Old 8th January 2011, 06:07 PM   #1
diyAudio Member
 
Join Date: Aug 2004
Location: UK
Send a message via MSN to audio_tony
Default My latest project - 60w per channel amp (just pics)

After languishing in my project box for about 2 years, I finally got around to building this amp, based on two modules bought off that well known auction site.

My original intention was to make these into mono blocks, and I'm still undecided about doing that. As it stands here, it's built into a Cambridge A5 chassis that I had (amp was blown).

I still have some work to do, such as fitting some snubber caps across the rectifiers, and also some additional filtering on the PSU. I also have a set of four matched caps to replace the 'prototypes' you see here.

The sound is very good, which doesn't surprise me, as I believe these amps were based on a Musical Fidelity design.

I may also look at reducing the overall gain, as it currently seems a bit high when used with a preamp. This may or may not be a good thing..

All comments (bad or good!) welcome.
Attached Images
File Type: jpg Power-Amp-Overall.jpg (775.8 KB, 528 views)
File Type: jpg Power-Amp-boards.jpg (686.7 KB, 474 views)
File Type: jpg MX50X2-02.jpg (39.1 KB, 492 views)
__________________
Searchable DAC list (now in a database). * Easy searching of DAC chips / transport etc. *
  Reply With Quote
Old 8th January 2011, 09:56 PM   #2
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Looks good The problem with the Cambridge amps can be seen easily - that heatsink is rubbish and the Sanken SAP transistors used in the circuit blow up due to overheating.

I'd neaten up the power wiring a bit. The best thing to do is to twist together the +V, -V and GND wires and run them back to the psu. This keeps interference down. I'd use some screened cable for your signal inputs too.
  Reply With Quote
Old 8th January 2011, 10:49 PM   #3
Banned
 
Join Date: Jan 2005
Yes those heatsinks made from a thin aluminum plate and folded aluminum/steel sheet are the worst heatsinks you can find!! I HATE HATE HATE them!!
  Reply With Quote
Old 9th January 2011, 08:58 AM   #4
diyAudio Member
 
Join Date: Aug 2004
Location: UK
Send a message via MSN to audio_tony
Yes I had planned to tidy up the wiring. I used some quite thick 42 strand cable, and it's quite unmanageable really. I need to use something thinner I think.

And those heatsinks... yes, I know they are rubbish, and again I am looking to replace them. As I'm still undecided about whether or not to make this into monoblocks, I haven't yet decided which heatsinks to go for.
__________________
Searchable DAC list (now in a database). * Easy searching of DAC chips / transport etc. *
  Reply With Quote
Old 20th January 2013, 02:24 PM   #5
diyAudio Member
 
Join Date: Aug 2004
Location: UK
Send a message via MSN to audio_tony
Default Amp now has a new home.

As of this weekend, the project now has a new home.

A Rotel RB-956AX 6 channel amp gave up it's life for the cause

My first chassis (A Cambridge A5) used the Cambridge heat sinks which were grossly inadequate.

After some searching, I concluded that one of the Rotel power amps would have suitable heat sinks, and when the 956AX came up on Ebay at a good price, I bought it. After having listened through it for a few days, I decided it wouldn't be too much of a travesty if i used it for spares.

I had to bend the legs of the transistors to make them into the original Rotel heat sink holes, as I was reluctant to drill the heat sink - also the bolt holes in the transistors didn't line up with the spaces between the fins (so I would have needed to move the transistors anyway), so that was what prompted me to simply relocate the transistors. It doesn't look nice, but so what?

I also have 2 Cambridge A5 mains transformers that I was going to use for this - however, the Rotel has a rather large toroidal (24-0-24 Vac) which is pretty much perfect for these amps, given that my speakers are 4 ohms.

On our slightly high mains here, I'm seeing about 36-0-36 Vdc.

I also used the original Rotel rectifiers and smoothing caps (6800uF 50v Rubycon), which has kept the PSU nice and simple. There are 3 individual secondary windings (each 24-0-24) on the transformer, and the PSUs are completely separate from each other - so this is essentially 2 monoblocks in one box.

Even playing at relatively highish levels, the heat sinks now remain cold (perhaps too cold!).

So on to the pictures.
Attached Images
File Type: jpg P1010369.JPG (170.0 KB, 262 views)
File Type: jpg P1010371.JPG (149.4 KB, 220 views)
File Type: jpg P1010374.JPG (142.9 KB, 152 views)
File Type: jpg P1010375.JPG (149.9 KB, 133 views)
File Type: jpg P1010378.JPG (142.3 KB, 114 views)
File Type: jpg P1010379.JPG (99.3 KB, 107 views)
__________________
Searchable DAC list (now in a database). * Easy searching of DAC chips / transport etc. *
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
My latest project - DAC + headphone amp gmarsh Digital Line Level 105 13th December 2010 02:31 PM
My new project, 2 x KT88 60W amp zafira1981 Tubes / Valves 31 27th January 2007 09:37 PM
Sneak peak into my latest project... pics ;) Audiophilenoob Multi-Way 108 27th August 2005 10:19 PM
pics of latest project revisorn Multi-Way 3 5th September 2003 02:44 PM
My 4 channel car Amp distorting on 1 channel (large pics) MikeHunt79 Car Audio 9 3rd September 2003 06:41 AM


New To Site? Need Help?

All times are GMT. The time now is 10:17 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2