The T-Rex SET Amplifier DIY project - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 3rd February 2005, 06:16 AM   #11
diyAudio Member
 
audiousername's Avatar
 
Join Date: Jul 2004
Location: Melbourne, Victoria
Peter, the T-Rex is somewhat complex, but not unreasonably so. The signal circuitry only consists of two 5687s and a 300B!

If you are really looking for a challenge, have a look at Steve Bench's 813 Matrix Amplifier. Basically regulated everything, cute magic-eye indicators dancing in time with the music, and the warm glow that only transmitter valves' W-Th filaments can provide

It is very well thought out - to the extent of making sure that the HV disappears if bias is lost, and ensuring the ambient light is sufficient for the gas regulator valves to mainatin a constant voltage drop. But it is extremely complex.

Oh, and it's no slouch when it comes to output power either: 66W per channel.

Of course there's the obligatory safety warning. This thing uses an 800V supply
__________________
Jason
  Reply With Quote
Old 3rd February 2005, 06:58 AM   #12
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Default The T-Rex SET Amplifier DIY project

Quote:
Originally posted by Peter Daniel
I've been suggested to put together this amp. Since I don't have any experience whatsoever with tubes, I would be at least interested what do you think about the amp's concept. Is it worth the effort, considering that all the parts are practically available to me
Quote:
Originally posted by Peter Daniel
I'll be commisioned to build it, so it's not even for my personal use
So, go for it.
Quote:
Originally posted by Peter Daniel
I was under the impression that this is a complete and well tuned design. I'm not really planning to do any tweaking, just follow the schematic and parts choices used by the amp's designer
John Broskie is no fool when it comes to tube design, so I'd be surprised if it didn't work very well. And contrary to opinion, it's not that complex, no more so that something that sounds really mediocre like the Flesh and Blood. Shunt feedback works really well; I've been running a Pimm PP47 for a couple of years now and this amp, as well as a couple of others I've built to experiment with has completely changed my mind about FB and pentodes.

If it were PP, I'd try one myself; don't have the iron for SE and I generally don't like SE amps (though I do have a parafeed 813 under construction - mainly because I have the parts and only 3 STC813's). It'd also be interesting to see whether the partial FB works to negate some of the value of the expensive 300B's, ie would a Sovtek be closer to a WE in this amp?
Quote:
Originally posted by serengetiplains
Peter, go for it! Survey peoples' opinions about regulated output supplies. You'll probably see a majority saying regulation works sonically. Here are thoughts I've had about this issue, which preceded Olsher publishing his new amp. Most amps regulate every other supply to evidently good effect. I suppose the reason output supplies are not regulated is due to added complexity which, if solvable, leaves the problems of added cost and heat. I also note that the Lamm SE amp is receiving accolades from people who sound to me like they know how to listen (J. Valin, among others). The Lamm uses (probably shunt) regulation in its output supply. Also check out the Audio Note comments on a shunt regulated preamp --- AN says "oooh" regarding it.
Shunt yes, series no.

Peter, I'm looking forward to seeing what sort of chassis you come up with for this amp
  Reply With Quote
Old 3rd February 2005, 07:10 AM   #13
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Default Re: The T-Rex SET Amplifier DIY project

Quote:
Originally posted by Brett
Peter, I'm looking forward to seeing what sort of chassis you come up with for this amp
ditto that...

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 3rd February 2005, 07:18 AM   #14
diyAudio Member
 
serengetiplains's Avatar
 
Join Date: Feb 2004
Location: Canada
Default Re: The T-Rex SET Amplifier DIY project

Quote:
Originally posted by Brett
Shunt yes, series no.
Depends on the topology but, yes, for class A circuits, shunt, which be what the T-Rex offers.
  Reply With Quote
Old 3rd February 2005, 12:26 PM   #15
kmtang is offline kmtang  Canada
diyAudio Member
 
kmtang's Avatar
 
Join Date: Nov 2004
Location: Vancouver
I have read the same article too few weeks ago. It sound very interesting but I won't consider to build it in near future.

I have an idea. I think it would be nice to build the amp with separate HT power supply unit. All filament transformer are kept inside the chassis.

Just my 2 cents.

Johnny
  Reply With Quote
Old 3rd February 2005, 12:57 PM   #16
protos is offline protos  Greece
diyAudio Member
 
protos's Avatar
 
Join Date: Mar 2002
Location: Athens+Addis Ababa
Peter,
I was expecting one of these days you would try your hand at tubes.Anyway this amp seems to have the right pedigree.Of course there are some other ' advanced' set designs out there but then nobody will agree which is the best as always.
I am sure your chassis will be great although for me this guy here has done one of the best ever chassis I have ever seen:

http://www.jogis-roehrenbude.de/Lese...n-6C33-Amp.htm
But then who has access to big milling machines?
  Reply With Quote
Old 3rd February 2005, 02:27 PM   #17
paba is offline paba  Canada
diyAudio Member
 
Join Date: Sep 2004
Location: Montreal
Peter, by all means go for it. I believe the T-REX design is one of the better "newish" designs. The power supply has much more thought behind it than several top of the line commercial and DIY tube amps out there. Also little noise cancellation techniques used will make it very special.

I've considered building it myself as well but was waiting for Audio Oassis to sell the PCB. They say it still not around the corner. Sounds like you have a good relationship with Piltron and AO so you are in a unique position because this no compromise amp will cost around $2K by my guess.

You will have a flag ship amp that deserves it's name. Don't forget all the man hours that has gone into this design by some very very respected names. I think they started thinking about it as fas back as 2001.

The parts list shows some very basic parts except for the Iron of course. Knowing you, you should tap into your pile of boutique caps and resistors.

Good luck and please keep us informed.
Paba
  Reply With Quote
Old 3rd February 2005, 02:30 PM   #18
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Re: The T-Rex SET Amplifier DIY project

Konnichiwa,

Quote:
Originally posted by Peter Daniel
I've been suggested to put together this amp. Since I don't have any experience whatsoever with tubes, I would be at least interested what do you think about the amp's concept. Is it worth the effort, considering that all the parts are practically available to me

http://www.enjoythemusic.com/magazin.../0105/trex.htm
I found the design interesting and an illustration of how you can use two very differnet pathways to attain the results.

I do see some oddities though, that would make me question the actual operation of some of the items and it appears a little as if someone took "building blocks" from a number of philosophies and strung them together somehow with a modest disregard for the inherent philosophies and principles behind the circuits.

Sort of like a horse designed by a comittee.

Some items that would concern me:

1) 300B Heater Supply. That particular approach taken is BAD. Even straight AC sounds better. AT THE VERY LEAST you should use Schottky Diodes and CRC Filtering, preferably some CMC Chokes as well.

2) Output Stage Feedback. Here a 47k feedback resistor sor shunt/parallel feedback is connected into the output of a 5687 SRPP (maybe 1K output), which means that other in terms of the textual writing virtually no NFB is actually present.

MUCH MORE milage and some actual sensible NFB use could be attained returning the 300B Cathode bypass capacitors to the output transformer secondary winding in the right polarity, then that particular cludge. Alternatively, returning the NFB (with the NFB resistor adjusted to suit) to the 5687 SRPP circuit cathode and leaving the bypass capacitor off there again would give some decent milage.

Alternatively you may omit the C8 & R15 with practically no change in measured and subjective performance (try it).

3) Main Powersupply. The signal return for our amplifier which is practically zero NFB is made through a high NFB circuit. In effect this makes the Amp more or less of a Push-Pull Amplifier in nature. Using such regulated supplies can nevertheless sound quite good, but usually requires some tweaking to get teh right sound, the regulators are often "too good" (and too non-linear) for their own good, managing to impose their own sound reliably on the signal.

I found that when comparing the (also noted and expounded by Broskie) optimised WE style output stage cathode decoupling the results where as good and/or better than any attained with extensive supply regulation.

Overall I think that the Amp could have done with a bit more "optimising and integrating the bits" which could have resulted in reducing the "material battle" this amp clearly is and at least based on my experience would have provided even better results. But that I have to agree is just me, so don't take me too serious.

If you like, you can build two pairs and I'll send you off-line some suggestions to "make it better" without departing too far from the spirit of the design.

Sayonara
  Reply With Quote
Old 3rd February 2005, 03:36 PM   #19
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Default Re: Re: The T-Rex SET Amplifier DIY project

Quote:
Originally posted by Kuei Yang Wang
If you like, you can build two pairs and I'll send you off-line some suggestions to "make it better" without departing too far from the spirit of the design.
I will be definitely interested in any suggestions. I don't neccessarily have to stick with the exact design, and if the changes bring improvement, I will surely implement them.

I was planning to build PS and the amp in separate enclosures. Should I go with monos or one chassis for the amp section?

Quote:
Originally posted by paba
I've considered building it myself as well but was waiting for Audio Oassis to sell the PCB. They say it still not around the corner.
If the boards will be offered by Audio Oasis, it will be based on my work here and I will be designing the layout. So again, any input is appreciated.

"The T-Rex is now in the public domain for the benefit of the DIY community", and since commercial rights are reserved, I will be not profiting on those boards.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 3rd February 2005, 04:12 PM   #20
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Here's the suggested layout for Plitron chassis (size is 22 x 17") This thing is quite big.
Attached Images
File Type: jpg pli.jpg (98.6 KB, 1412 views)
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  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
Amplifier Project gbowne1 Tubes / Valves 16 24th April 2008 10:55 PM
Pre-amplifier Project Help tumler Solid State 2 8th August 2007 10:15 PM
New Amplifier Project The Peasant Solid State 40 7th February 2005 11:15 AM
What is the best amplifier project...? Danyele82 Solid State 11 2nd May 2004 02:05 PM
My new amplifier project sajti Solid State 7 14th August 2003 02:15 PM


New To Site? Need Help?

All times are GMT. The time now is 07:12 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