Hi Everyone, after a protracted hiatus from the forum and analogue audio, I decided to re-enter the fold! I got to dust off my Audio Electronic Supply SE-1 amp with 300B tubes and my AES AE-3 preamp, that I put together about 20 years ago.
Now that I have some free time on my hands, I realized that there must be loads of modifications that can be done on both units to enhance the sound. Does anyone have a list of mods or suggestions on how to re-energize these 2 great units?
Thanks for your help and advice!
Roger
Now that I have some free time on my hands, I realized that there must be loads of modifications that can be done on both units to enhance the sound. Does anyone have a list of mods or suggestions on how to re-energize these 2 great units?
Thanks for your help and advice!
Roger
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I also have an AE-1 that I built years ago. Great little preamp, I wish I had the power amp.
The preamp came with really nice capacitors and a good power supply so I don't know of any mods there. I did modify the amp with a single volume and balance set up. When I ordered the amp kit, Dennis Had himself answered the phone and set me up with the volume and balance pots. I would like to reduce the low level hum that can be heard with ears close to the speakers. I am not crazy about all of the grounded terminal strips, won't be easy to do single point grounding. Also, it will be difficult to incorporate a signal ground lift bridge rectifier/resistor. Future project I will think about.
The preamp came with really nice capacitors and a good power supply so I don't know of any mods there. I did modify the amp with a single volume and balance set up. When I ordered the amp kit, Dennis Had himself answered the phone and set me up with the volume and balance pots. I would like to reduce the low level hum that can be heard with ears close to the speakers. I am not crazy about all of the grounded terminal strips, won't be easy to do single point grounding. Also, it will be difficult to incorporate a signal ground lift bridge rectifier/resistor. Future project I will think about.
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Mod Man, thanks for the reply. Sorry about the confusion, but I have the AE-3 version. Not sure of the differences iff any, and whether that makes a difference in mods...
The AE-3 is about the most minimalistic preamp circuit you can conceive of. It has a choke filtered power supply, a 6SN7 voltage amp input stage and a 6SN7 cathode follower output stage, with a three-terminal monolithic regulator powering the filaments. That's it.
There were several factory upgrades you could order when ordering the kit:
Mine had hum initially which I traced down to the volume pot housing not being well grounded. After scraping away some of the powder coating on the inside of the chassis around the volume pot mount hole, it fixed that hum, and mine has been dead quiet ever since.
There is not a lot written (that I could find) about upgrades to this preamp, other than the factory upgrades mentioned above. However, after living with mine for maybe 10 years I did change the following things:
Also it appears Dennis added a last minute Zener shunt regulator in the power supply. It's drawn differently in the schematic which leads me to believe it was added after the original design was complete. It's two 110V Zener's strung together in series and wired in between the choke output and ground. But on my unit, the Zeners never shunt anything because the power supply voltage at the point of the Zener shunt connection is 215V (with 122V wall socket voltage). So I just let it be, knowing the shunt isn't actually regulating anything, because the preamp sounded so good as is.
There were several factory upgrades you could order when ordering the kit:
- Hexfred diodes in the power supply
- Upgraded AudioOne paper in oil coupling caps
- Upgraded 6SN7 tubes.
- There was also an option to use a tube rectifier instead of diodes
Mine had hum initially which I traced down to the volume pot housing not being well grounded. After scraping away some of the powder coating on the inside of the chassis around the volume pot mount hole, it fixed that hum, and mine has been dead quiet ever since.
There is not a lot written (that I could find) about upgrades to this preamp, other than the factory upgrades mentioned above. However, after living with mine for maybe 10 years I did change the following things:
- DC couple the input stage to the output stage. It was originally AC coupled, and the factory upgraded coupling cap I mentioned above changed out this particular cap to the AudioOne cap. The thing is, Dennis biased the output stage exactly at the position that would would be needed if you DC coupled the stages. It's almost like he had it direct coupled initially and then at the last minute decided to AC couple. So I removed the coupling cap, the 1M grid leak resistor and the 2k self bias resistor in the cathode of the output stage, and connected the plate of the input stage directly to the grid of the output stage, as well as wired the 27k cathode resistor directly to the cathode of the output tube. I did these mods because while the amp sounded very good in "upgraded" stock form, it had just a bit of bloom. Removing that coupling cap and DC coupling the stages was more of the neutral sound I was looking for.
- Upgrade the output stage coupling caps to Jupiter copper foil 0.22 uF 400V caps. These are a bit larger than the factory output stage caps, but they did fit--just barely.
Also it appears Dennis added a last minute Zener shunt regulator in the power supply. It's drawn differently in the schematic which leads me to believe it was added after the original design was complete. It's two 110V Zener's strung together in series and wired in between the choke output and ground. But on my unit, the Zeners never shunt anything because the power supply voltage at the point of the Zener shunt connection is 215V (with 122V wall socket voltage). So I just let it be, knowing the shunt isn't actually regulating anything, because the preamp sounded so good as is.
Thank you! I honestly don't remember what if any options I ordered with the original kit. At the time, money was a really big issue, and just buying the kit was a stretch! I will open up the unit, and see what I can upgrade based upon your recommendations.
By the way, does anyone have a link for the AE-3 schematic? I have the SE-1, but can't seem to find the pre-amp.
This thread has a cell phone pic of the schematic.
Also, I mistakenly said I replaced the output coupling caps with 0.22 uF Jupiters. In fact they are 1 uF Jupiters, so in other words the same size as was provided by the factory in that location.
Also, I mistakenly said I replaced the output coupling caps with 0.22 uF Jupiters. In fact they are 1 uF Jupiters, so in other words the same size as was provided by the factory in that location.
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