Hi all,
I am after any information on Silicon Chip ULD 100 watt amp. I'd love to hear from anyone that has build one, or even if you have just heard one I'd be interested. I have all the Silicon Chip articles so I am really just after listening tests impressions.
I have done a search and only found one reference that was not very complimentary.
Here a link to the amp in question:
http://www.altronics.com.au/index.asp?area=item&id=K5155
If someone in Sydney has one, please drop me a PM.
Thanks
I am after any information on Silicon Chip ULD 100 watt amp. I'd love to hear from anyone that has build one, or even if you have just heard one I'd be interested. I have all the Silicon Chip articles so I am really just after listening tests impressions.
I have done a search and only found one reference that was not very complimentary.
Here a link to the amp in question:
http://www.altronics.com.au/index.asp?area=item&id=K5155
If someone in Sydney has one, please drop me a PM.
Thanks
Yes, I built the shortform kit a few years ago when I got interested in DIY power amps. It's quite a reasonable performer. Sonically, you would say that it's a little sterile sounding and the treble is a little cool and metalic, but it gives a very detailed presentation, particularly through the mid band, and an excellent soundstage. I use mine to power my mid and bass in a bi-amped system and it's excellent for that job. The circuit is similar to other SC project amps and at a glance not dissimilar to the Doug Self blameless amp. The CFP output stage is very linear but not particularly well suited to class B operation, particularly into low impedances (ie. < 6 ohms). The cascoded VAS is employed to lessen the effects of non linear VAS miller capacitance loading the input stage. In his articles, Douglas Self did not advocate a cascoded VAS for class B operation due to the high collector impedance. However, it would probably work very well with the protection of a well designed class A buffer stage, although I never got around to such a mod.
Hi David,
Thanks for taking the time to post. I assume by the "shortform kit" you mean you bought the separate amp kits and possibly the power supply kit rather than the "complete" amplifier kit. Did you use the standard components?
I noticed the Douglas Self blameless amp resemblance, also it's a bit like a slightly more complicated ESP P3A with the cascoded VAS and split regulated/unregulated power rails.
Good to hear you are happy with it. Have you compared it to other amps and what are you using for the tweeters.
I was beginning to wonder if anybody here had actually built one and I still hope a few more people will respond.
Thanks again.
Thanks for taking the time to post. I assume by the "shortform kit" you mean you bought the separate amp kits and possibly the power supply kit rather than the "complete" amplifier kit. Did you use the standard components?
I noticed the Douglas Self blameless amp resemblance, also it's a bit like a slightly more complicated ESP P3A with the cascoded VAS and split regulated/unregulated power rails.
Good to hear you are happy with it. Have you compared it to other amps and what are you using for the tweeters.
I was beginning to wonder if anybody here had actually built one and I still hope a few more people will respond.
Thanks again.
Greg,
Yes, I purchased the PCBs and parts, and I also sourced extra transistors in order to match vbe and beta in critical areas, and selected highest hfe. I built the power supply and amp modules in seperate cases and worked out a neat way of mounting (and insulating) high quality gold plated banana plugs to the underneath of the amp case and equivalent gold sockets on the top of the PSU case. The amp module can therefore be lifted on and off the PSU, and the PSU is of course magnetically shielded from the amp modules. For the unregulated supply rails I'm using 2 x 500VA (40-0-40) toroidals and 60,000 uF per voltage rail, per channel. I made up my own slow start or surge limiter which is powered from its own mini toroidal transformer. The regulated IS and VAS stages are also derived from a dedicated T T. And yes, I made up my own PSU PCB employing best practise layout.
So you see it's not exactly the same as the Altronics version. My bigger PSU probably gives the bass some extra authority but otherwise there's probably little audible difference to a well built Altronics kit.
My current tweeter amp is a low fb design with a push-pull Mosfet high bias Class AB output stage but I'm currently developing 2 new designs, one class A and the other 'AB'. They are still under development but if you like I can forward details when completed. I have a 24 bit AA so I can also let you see a distortion spectrogram and square wave performance too.
I'm going away for 4 days from early tomorrow so if you have further questions I'll be glad to answer them but it will be sometime mid next week.
Cheers,
Yes, I purchased the PCBs and parts, and I also sourced extra transistors in order to match vbe and beta in critical areas, and selected highest hfe. I built the power supply and amp modules in seperate cases and worked out a neat way of mounting (and insulating) high quality gold plated banana plugs to the underneath of the amp case and equivalent gold sockets on the top of the PSU case. The amp module can therefore be lifted on and off the PSU, and the PSU is of course magnetically shielded from the amp modules. For the unregulated supply rails I'm using 2 x 500VA (40-0-40) toroidals and 60,000 uF per voltage rail, per channel. I made up my own slow start or surge limiter which is powered from its own mini toroidal transformer. The regulated IS and VAS stages are also derived from a dedicated T T. And yes, I made up my own PSU PCB employing best practise layout.
So you see it's not exactly the same as the Altronics version. My bigger PSU probably gives the bass some extra authority but otherwise there's probably little audible difference to a well built Altronics kit.
My current tweeter amp is a low fb design with a push-pull Mosfet high bias Class AB output stage but I'm currently developing 2 new designs, one class A and the other 'AB'. They are still under development but if you like I can forward details when completed. I have a 24 bit AA so I can also let you see a distortion spectrogram and square wave performance too.
I'm going away for 4 days from early tomorrow so if you have further questions I'll be glad to answer them but it will be sometime mid next week.
Cheers,
Greg,
I forgot to mention, I have compared it to a Krell FPB 300 and an ME 1500 which Trevor Wilson carted over one evening. It wasn't as good as either but was in no way disgraced. Compared to the Krell it lacked hf resolution, and the transient attack and decay was a little less natural and life like. Compared with the ME 1500 it lacked some low end authority and dynamics. Of course both of those are far more expensive amplifiers and you would expect them to be better but the ULD was not disgraced and is a good 'all rounder'. It's probably comparable with something in the 3K - 4K price area.
I forgot to mention, I have compared it to a Krell FPB 300 and an ME 1500 which Trevor Wilson carted over one evening. It wasn't as good as either but was in no way disgraced. Compared to the Krell it lacked hf resolution, and the transient attack and decay was a little less natural and life like. Compared with the ME 1500 it lacked some low end authority and dynamics. Of course both of those are far more expensive amplifiers and you would expect them to be better but the ULD was not disgraced and is a good 'all rounder'. It's probably comparable with something in the 3K - 4K price area.
David,
Thanks again for your detailed response. You obviously have a nice setup.
Funny thing is, and I don't know if you're aware of it, I originally startup this post to try and get some independant feedback on the SC ULD amp. Over at aus.hi-fi just about ALL the information on the SC ULD has come from Trevor Wilson over many years. Now you bring him into the equation here.
Small world hey.
regards
Thanks again for your detailed response. You obviously have a nice setup.
Funny thing is, and I don't know if you're aware of it, I originally startup this post to try and get some independant feedback on the SC ULD amp. Over at aus.hi-fi just about ALL the information on the SC ULD has come from Trevor Wilson over many years. Now you bring him into the equation here.
Small world hey.regards
Thanks for the link, although I think that relates to the mk2 version of the ULD amp whereas the altronics kit is the mk1 version.
Hey, I just made one.
Matter of fact I just powered it up about 2 hours ago. Bought as a kit and it has a 5-star difficulty rating and they weren't kidding. I really didn't enjoy making this amp. It is to replace my old 50+50 watt 53 kilogram mosfet class A lump. In the 7 or so years since made that thing I have lost a lot of interest in hifi and also my ears have a bit of tinnitus. Turned on the new amp, played a single track to see that it worked and then went off to do something else. If I had realised how much work it would take to put this new amp together I think I would have paid someone else to do it.
Matter of fact I just powered it up about 2 hours ago. Bought as a kit and it has a 5-star difficulty rating and they weren't kidding. I really didn't enjoy making this amp. It is to replace my old 50+50 watt 53 kilogram mosfet class A lump. In the 7 or so years since made that thing I have lost a lot of interest in hifi and also my ears have a bit of tinnitus. Turned on the new amp, played a single track to see that it worked and then went off to do something else. If I had realised how much work it would take to put this new amp together I think I would have paid someone else to do it.
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A few comments fly in the face of the ULD Mk1 design brief in this thread. The ULD amp is an "8 ohm only" design, and yes, you would expect it to have problems supplying high current into 4 or even 6 ohm loads. That's an unfortunate choice and even the 300VA toroid, is only just enough for that.
The unusual design choices, I expect, were as much to avoid plagiarism as try other variants from Self's list of options. The design first appeared in 1999 as an electronic hobbyist's project, mounted in a mid-tower PC case for cost reasons. The concept was not what we now commonly seek in amps. As Greg referred to the later Altronics makeover kit, you can see how tight things are in Circlotron's kit build. At the special price, I think you still have a great amp and there's little stopping a retrofit of the newer ULD II EF thermaltrak modules and removing the regulated input stage PS, if the CF topology offends you.
There has been a huge amount of discussion and development since DIYAudio went online and popularised High-end design at budget prices. Commercial kits like this one are virtually as costly as a retail product so the price will reflect a lot of economies we may not, in our enthusiasm, wish to make. To supply a 100 W kit to current standards with the features of the ULD kit would cost more like $1,000 AU now.
I reckon you did well for the money there Circlotron, I hope it runs like a dream. I'm very happy with my "A" class choice for all the hassle the kit saved me. Now, we just need a few worthwhile simple mods to tweak it. If Sandyk is about, I'm sure he'd be willing to share.... .
The unusual design choices, I expect, were as much to avoid plagiarism as try other variants from Self's list of options. The design first appeared in 1999 as an electronic hobbyist's project, mounted in a mid-tower PC case for cost reasons. The concept was not what we now commonly seek in amps. As Greg referred to the later Altronics makeover kit, you can see how tight things are in Circlotron's kit build. At the special price, I think you still have a great amp and there's little stopping a retrofit of the newer ULD II EF thermaltrak modules and removing the regulated input stage PS, if the CF topology offends you.
There has been a huge amount of discussion and development since DIYAudio went online and popularised High-end design at budget prices. Commercial kits like this one are virtually as costly as a retail product so the price will reflect a lot of economies we may not, in our enthusiasm, wish to make. To supply a 100 W kit to current standards with the features of the ULD kit would cost more like $1,000 AU now.
I reckon you did well for the money there Circlotron, I hope it runs like a dream. I'm very happy with my "A" class choice for all the hassle the kit saved me. Now, we just need a few worthwhile simple mods to tweak it. If Sandyk is about, I'm sure he'd be willing to share.... .
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Looks very similar to the front-cover amp of April 1996 even.
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That's interesting and cetainly a real bargain, Agisthos. I guess you have the Altronics kit which was based on the first, rather complex, design. 'Nice kit though and many say it sounds better than version II with the simplified Thermaltrack output stage or even the newest, MKIII version.
I think there may have been some hasty conclusions drawn there since you can't simply swap the amplifier boards for fair comparison. There are separate. regulated supplies to the input and cascoded VAS stages for starters.
So - has anyone actually checked out the sound quality of this newest, Nicholas Vinen's, version yet?
I think there may have been some hasty conclusions drawn there since you can't simply swap the amplifier boards for fair comparison. There are separate. regulated supplies to the input and cascoded VAS stages for starters.
So - has anyone actually checked out the sound quality of this newest, Nicholas Vinen's, version yet?
ahhh... another ebay purchase that has a problem ...... wonderful.
The right channel volume is soft / or cuts in and out, until hitting about 10am on the knob. After that is fine... but any normal/low level listening is not possible.
Would this be a volume pot issue or a problem with one of the amplification modules?
The right channel volume is soft / or cuts in and out, until hitting about 10am on the knob. After that is fine... but any normal/low level listening is not possible.
Would this be a volume pot issue or a problem with one of the amplification modules?
ULD with a glitch
Assuming this is the Altronics Mk1 kit, there are no electronic switches in the signal path so the fault will be mechanical, unless accompanied by distortion in the right channel which should be obvious. Before getting serious, disconnect the left channel speaker and verify the sound quality of the right channel as you rotate the volume control. If it is faulty, the mechanical sound as you rotate it about the 10 0'clock position should demonstrate that cause more obviously.
If the switching in or out is more abrupt and sounding like an on/off switch, there is something mysterious to discover, indeed. All the same. wiggle the control about to make sure that weak soldering of the connections is not the culprit either.
Considering the probable age. use and budget quality of the pot. a replacement is the likely solution and I'll wager it's had a few knocks in it's exposed position too.
So, what do you find?
Assuming this is the Altronics Mk1 kit, there are no electronic switches in the signal path so the fault will be mechanical, unless accompanied by distortion in the right channel which should be obvious. Before getting serious, disconnect the left channel speaker and verify the sound quality of the right channel as you rotate the volume control. If it is faulty, the mechanical sound as you rotate it about the 10 0'clock position should demonstrate that cause more obviously.
If the switching in or out is more abrupt and sounding like an on/off switch, there is something mysterious to discover, indeed. All the same. wiggle the control about to make sure that weak soldering of the connections is not the culprit either.
Considering the probable age. use and budget quality of the pot. a replacement is the likely solution and I'll wager it's had a few knocks in it's exposed position too.
So, what do you find?
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