Hi Sithlord2007,
There are many things you can do to improve your amplifier's sound quality. Bridging the output isn't one of them. As rrcain said, "WHY?".
I have restored these amplifiers and can tell you that they are much better than the appearance would suggest. These are a hidden gem if gone over properly. There are some other resistor choices that can be made for certain ones. Some transistors should be matched and certain capacitors need to be changed to different types. Once that is done you won't believe it is the same amplifier.
Just don't bridge amplifiers! This one isn't designed for that kind of abuse, and its too nice an amp to trash.
Ahhh, just curious. That's fine. If you have three of these, look after them and consider an active three way crossover. These amplifiers are well worth improving, but this is not something the average person can do at home. You need experience and the right test equipment
-Chris
There are many things you can do to improve your amplifier's sound quality. Bridging the output isn't one of them. As rrcain said, "WHY?".
I have restored these amplifiers and can tell you that they are much better than the appearance would suggest. These are a hidden gem if gone over properly. There are some other resistor choices that can be made for certain ones. Some transistors should be matched and certain capacitors need to be changed to different types. Once that is done you won't believe it is the same amplifier.
Just don't bridge amplifiers! This one isn't designed for that kind of abuse, and its too nice an amp to trash.
Ahhh, just curious. That's fine. If you have three of these, look after them and consider an active three way crossover. These amplifiers are well worth improving, but this is not something the average person can do at home. You need experience and the right test equipment
-Chris
Last edited:
Lol ... Guys, I appreciate the advice. But I'm not a 15 year old kid that got the keys to dad's 69 mustang and wants to joy ride.
I've been an audio enthusiasts for about 28 years. I've amassed a large collection of Heathkit and Speakerlab gear and am the type of audiophile that will never part with what I have even if I eventually stop using them.
Three AA 1800's and an AA-1600 ... All in impeccable condition and in my possession for nearly two decades. Not to mention the other stuff in the family.
Since I asked, I found the manual, but it doesn't mention bridging. However, I know what needs to be done in order to do it.
The question was just out of curiosity. But it's funny how people say to TRY something and if if sounds good to you, then that's fine. Lol!!!
I'm not gonna trash anything. I understand the design quality of these units. As a matter of fact, I love them so much, I've only considered replacing them with KRELL components ... Such as I have already done with my AP 1800 Preamp with a KRC HR. Meaning, I haven't come across much that can match them sonically except for some really high end stuff. And now that Krell is a bit more in my budget, I've been making some system upgrades. Those 1800's, I suspect, will be in service for another 5-10 years for me.
Thanks for the advice and the caution.
Ed
I've been an audio enthusiasts for about 28 years. I've amassed a large collection of Heathkit and Speakerlab gear and am the type of audiophile that will never part with what I have even if I eventually stop using them.
Three AA 1800's and an AA-1600 ... All in impeccable condition and in my possession for nearly two decades. Not to mention the other stuff in the family.
Since I asked, I found the manual, but it doesn't mention bridging. However, I know what needs to be done in order to do it.
The question was just out of curiosity. But it's funny how people say to TRY something and if if sounds good to you, then that's fine. Lol!!!
I'm not gonna trash anything. I understand the design quality of these units. As a matter of fact, I love them so much, I've only considered replacing them with KRELL components ... Such as I have already done with my AP 1800 Preamp with a KRC HR. Meaning, I haven't come across much that can match them sonically except for some really high end stuff. And now that Krell is a bit more in my budget, I've been making some system upgrades. Those 1800's, I suspect, will be in service for another 5-10 years for me.
Thanks for the advice and the caution.
Ed
Last edited:
Hi Ed,
Well, we just never know what your experience or intentions are. I come from this from a purely technical viewpoint. This next phrase sends shivers up my spine ...
I have rebuilt a few of those combinations of equipment, and they never fail to put a smile on my face. As you have noted, they sound better than most other equipment out there. A true sleeper.
-Chris
Well, we just never know what your experience or intentions are. I come from this from a purely technical viewpoint. This next phrase sends shivers up my spine ...
One of the most idiotic comments I commonly hear. Probably responsible for more damage out there, and hearing it makes me a little angry as well. Hey! I am a technician, that is where I come from.
I have rebuilt a few of those combinations of equipment, and they never fail to put a smile on my face. As you have noted, they sound better than most other equipment out there. A true sleeper.
-Chris
Do you know of anyone in the states that repairs/restores vintage Heathkit gear - especially the AA-1800's little brother the AA-1600? Sounds like you may have at one time. I've got one sitting in my basement that's been out of service now for about 3 years. It developed some static in one channel before we moved and I've got neither the inclination or equipment to bring back to its full glory. It sounded great though.
I've also got the matching pre-amp AP-1800 that works, but I suspect it's ready for a serious recapping. I got both pieces several years ago on trade because as a young grad student in the mid 70s I always coveted Heathkit's 'high-end' gear but was never able to afford any pieces.
Rick
I've also got the matching pre-amp AP-1800 that works, but I suspect it's ready for a serious recapping. I got both pieces several years ago on trade because as a young grad student in the mid 70s I always coveted Heathkit's 'high-end' gear but was never able to afford any pieces.
Rick
Hi Rick,
Try Terry DeWick. Your equipment is good enough to warrant his level of attention. If you can't use him, then the guy you want is in his 50's at the youngest. You need a good audio technician, not a TV, band equipment or computer technician. That person should recognize just how nice your equipment can sound and how to get it to that level.
I have serviced many Heathkit products over the years, and a few years ago a friend let me do whatever I felt would increase the sound quality to his Heathkit equipment. He gave me one of his (very) distressed preamps. I think I will service it and use it on the bench where good looks aren't that important. They do sound great! Too bad he didn't have a banged up amplifier to go with it. To give you perspective, I had also gone over his Marantz equipment, and I even made his Pioneer tuner sound good and perform much better. I got rid of that annoying Pioneer sound with the funny midrange thing going on. His McIntosh equipment was a little more straight forward to make sound good again.
I wish you luck on this. Too bad you don't live on this side of the border!
Best, Chris
Try Terry DeWick. Your equipment is good enough to warrant his level of attention. If you can't use him, then the guy you want is in his 50's at the youngest. You need a good audio technician, not a TV, band equipment or computer technician. That person should recognize just how nice your equipment can sound and how to get it to that level.
I have serviced many Heathkit products over the years, and a few years ago a friend let me do whatever I felt would increase the sound quality to his Heathkit equipment. He gave me one of his (very) distressed preamps. I think I will service it and use it on the bench where good looks aren't that important. They do sound great! Too bad he didn't have a banged up amplifier to go with it. To give you perspective, I had also gone over his Marantz equipment, and I even made his Pioneer tuner sound good and perform much better. I got rid of that annoying Pioneer sound with the funny midrange thing going on. His McIntosh equipment was a little more straight forward to make sound good again.
I wish you luck on this. Too bad you don't live on this side of the border!
Best, Chris
Does anyone know where I can find a service manual, owners manual or build manual for the Heathkit AP-1800 preamp? Thanks.
oldraider76@gmail.com
oldraider76@gmail.com
The AA-1640 kit manual is 160+ pages including the assy. manual for the little voltage meter you use during check out. Only Heathkit would do this. I wish I had been born about 10 years earlier as I missed the heyday of these kits. It's a shame kids don't get into this stuff anymore, it's all thumb exercises with texting and videos games.
Craig
Craig
Hi Craig,
Yes, you missed a great company with the kits. They were well thought out and very durable. You certainly did get your money's worth with a Heathkit. I built an IM-18 VTVM. Still have it and it still works fine. I also more recently got a Heathkit kit off Ebay for a transistor tester. So I was able to build another instrument doing something enjoyable. The biggest problem I had with that kit was oxidized switches. Now it works fine.
-Chris
Yes, you missed a great company with the kits. They were well thought out and very durable. You certainly did get your money's worth with a Heathkit. I built an IM-18 VTVM. Still have it and it still works fine. I also more recently got a Heathkit kit off Ebay for a transistor tester. So I was able to build another instrument doing something enjoyable. The biggest problem I had with that kit was oxidized switches. Now it works fine.
-Chris
I still have three unbuilt Heathkit tube kits I got at the swap meet years ago. A stereo FM generator, a HV regulated PS and a color pattern generator for TV service. Unfortunately none of them are worth building today. The specs aren't good enough for today's FM work and I already have three Heathkit HV power supplies. No comment on the TV generator. So what to do? Steal the Mullard tubes and use them elsewhere.
Craig
Craig
Those that want the schem. for the Heathkit AA1800 and AP1800 please email me at njvet01@yahoo.com I have some full size copies I made and If you want one please let me know. I would need your address to send the copies.
I have the full compliment of the Pro series components. AA 1800 ,AA1600 , AP 1800 , AJ1600 , AD1701 , all presently in use.
To fix the intermittent input jacks on the AP1800 I soldered the shell to the ground tab on the RCA jacks. The ground tabs are only crimped and the connection isn't really that good. Soldering the tab and the shell together fixes the intermittent input problem. I have not figured out what to replace the RCA's with as most connectors will not fit in the space that the original sockets are in. I would like to use BNC's but they are too big. Any suggestions about what to replace the RCA 's with ?
Hope this helps
Ed
I have the full compliment of the Pro series components. AA 1800 ,AA1600 , AP 1800 , AJ1600 , AD1701 , all presently in use.
To fix the intermittent input jacks on the AP1800 I soldered the shell to the ground tab on the RCA jacks. The ground tabs are only crimped and the connection isn't really that good. Soldering the tab and the shell together fixes the intermittent input problem. I have not figured out what to replace the RCA's with as most connectors will not fit in the space that the original sockets are in. I would like to use BNC's but they are too big. Any suggestions about what to replace the RCA 's with ?
Hope this helps
Ed