Kevin
I think you may be referring to the ETI5000 by David Tilbrook.
I no longer have the article, but having built this project, and the later AEM6000 by David Tilbrook, I can assure you that using the original design without modifications, the performance was nowhere nearly as good as the AEM6000, or it's little brother, the AEM6005.These are much better performers. The original ETI5000 could sound quite harsh, particularly until fully warmed up.
The EETI 477 was published in ETI (Australian edition) in February 1981, if that is of any help.
SandyK
I think you may be referring to the ETI5000 by David Tilbrook.
I no longer have the article, but having built this project, and the later AEM6000 by David Tilbrook, I can assure you that using the original design without modifications, the performance was nowhere nearly as good as the AEM6000, or it's little brother, the AEM6005.These are much better performers. The original ETI5000 could sound quite harsh, particularly until fully warmed up.
The EETI 477 was published in ETI (Australian edition) in February 1981, if that is of any help.
SandyK
Have you seen this site?
Suzyj has some interesting information about her version of the ETI477/AEM6000
http://www.littlefishbicycles.com/poweramp/index.html
There is also a thread concerning this amp. Search for suzyj.
regards
Suzyj has some interesting information about her version of the ETI477/AEM6000
http://www.littlefishbicycles.com/poweramp/index.html
There is also a thread concerning this amp. Search for suzyj.
regards
The ETI477 (used in the ETI5000 poweramp) used a bipolar input stage (BC550s), not JFETs. The later AEM6000 and AEM6005 amps used the ECG461 matched JFET.
I've got a scan of the ETI477, here .
The design has been discussed previously, see the ETI5000 thread.
I decided to do an amp based on the later AEM6000. I changed the input JFETs, as well as a few other transistors, and optimised the design for low THD using spice (as documented on my website). My amp has been running for a while, and I'm extremely happy with it.
I've got a scan of the ETI477, here .
The design has been discussed previously, see the ETI5000 thread.
I decided to do an amp based on the later AEM6000. I changed the input JFETs, as well as a few other transistors, and optimised the design for low THD using spice (as documented on my website). My amp has been running for a while, and I'm extremely happy with it.
ETI 477
I built both the ETI5000 and the AEM6000. I did not recommend the ETI5000 as I found it mediocre . It also had a design flaw which I was able to discuss personally with David Tilbrook. This (from memory) involved the 2nd stage pair being very unbalanced as far as heat dissipation was concerned, which in turn tended to unbalance the front end a little. I inserted an 18V zener diode in one side to equalise. David Tilbrook agreed, and this area was mentioned in the article about the 6000. I no longer have this circuit , so I can't be more specific. I also used separate transformers for each channel with improved results. This did not agree with Tilbrook's reasoning at the time. However he did this differently in the 6000. I also heard another ETI5000 at a Jaycar store, and again was less than impressed with the original unmodified amplifier.
SandyK
I built both the ETI5000 and the AEM6000. I did not recommend the ETI5000 as I found it mediocre . It also had a design flaw which I was able to discuss personally with David Tilbrook. This (from memory) involved the 2nd stage pair being very unbalanced as far as heat dissipation was concerned, which in turn tended to unbalance the front end a little. I inserted an 18V zener diode in one side to equalise. David Tilbrook agreed, and this area was mentioned in the article about the 6000. I no longer have this circuit , so I can't be more specific. I also used separate transformers for each channel with improved results. This did not agree with Tilbrook's reasoning at the time. However he did this differently in the 6000. I also heard another ETI5000 at a Jaycar store, and again was less than impressed with the original unmodified amplifier.
SandyK
If anyone requires a reasonable copy of the ETI 477 schematic for their personal records, please email me. I can't guarantee that all the component numbering is correct due to discolouration of paper with age. An educated guess had to be made with some numbering. The parts list should clear up any problems.
N.B. The file is about 2.2MB, as it was found to be needed for clarity.
SandyK
N.B. The file is about 2.2MB, as it was found to be needed for clarity.
SandyK
sandyK said:
Hi.
Yes you are completey correct that the NTE461 is very difficult to source.
However WHOLESALE ELECTRONICS in the US still has limited supplies of them. http://www.weisd.com
As an alternative to the 461 device, I believe that BFQ16 dual fet was a suitable alternative. However this one may be even more difficult to obtain.
Regards,
George.
ETI 477 schematic & pics
I am a friend of SandyK. Years ago he gave me his modified ETI 5000 amp with 477 modules, I still have it. Here is the circuit diagram (for an original, unmodified module) . I will also post some pictures, due to the size, one per post.
SuzyJ, I would be happy to loan you this amplifier to compare with yours, if you wish.
I am a friend of SandyK. Years ago he gave me his modified ETI 5000 amp with 477 modules, I still have it. Here is the circuit diagram (for an original, unmodified module) . I will also post some pictures, due to the size, one per post.
SuzyJ, I would be happy to loan you this amplifier to compare with yours, if you wish.
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