I just got these about 5 hours ago for free. They where in a trailer park down the street from my brothers house. 3 Grommes Precision G101A Power Amplifiers (Pretty long story about how I found out about them). Not in the best shape but at 100w mono on each and the free price tag how could I leave them to go in the trash. I was glad I could save them. Any opinion on these? are they worth the time to fix? 100 watt mono block tube amps sound interesting. Thanks
Just read the story on AK, great score! They are definitely worth restoring - would make good PA or guitar amps. The output tubes are 6GT5's with Novar sockets, which you may want to convert to octal's, so more common tubes can be used. Here is the schematic:
can not use as hifi or guitar .open and remove all like pot ...socket ....clean chassis and wiring again .some parts should replace .
ah - Al Hart's cascode front end - that and his cascode phono preamp probably spurred the Paragon and other tube preamps (such as Bruce Moore's stuff) Fantastic "gift" and very valuable amps .
I had a letter from Al with a hand sketch of his cascode 12ax7 RIAA feedback eq phono stage - he said he preferred his new op amp stuff - ha. (I have an old 6 channel diy tube mic mixer - each channel has a 12ax7 in cascode - it was very quiet with ribbon mics & its Altec mic transformers)
might take them completely apart and use naval jelly on the chassis. You could probably get it looking reasonably
good without full disassembly by carefully using Loctite naval jelly, Q-tips, etc. You have to get the jelly off somehow - paper towels damp rags - be careful not to touch the jelly as the phosphoric acid is pretty strong.
The transformers' cores look good - maybe lightly brush those, some folks recommend a "rust reformer" - then paint
Those are really impressive looking amplifiers.
I had a letter from Al with a hand sketch of his cascode 12ax7 RIAA feedback eq phono stage - he said he preferred his new op amp stuff - ha. (I have an old 6 channel diy tube mic mixer - each channel has a 12ax7 in cascode - it was very quiet with ribbon mics & its Altec mic transformers)
might take them completely apart and use naval jelly on the chassis. You could probably get it looking reasonably
good without full disassembly by carefully using Loctite naval jelly, Q-tips, etc. You have to get the jelly off somehow - paper towels damp rags - be careful not to touch the jelly as the phosphoric acid is pretty strong.
The transformers' cores look good - maybe lightly brush those, some folks recommend a "rust reformer" - then paint
Those are really impressive looking amplifiers.
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Here is the story of how I got them. I posted it on AK as well.
I first saw them on offer up and the guy wanted $25 for all 3 of them. That was 3 weeks ago. So I messaged him that I would take them but never heard anything back. I kept messaging him at least 2 times a week and yesterday he contacted me. He told me he no longer had them that he had to move quick and had to leave them when he left. That was 2 weeks ago when he moved. I asked him if he thought they might still be where he left them. He sent me the address of a rundown trailer park and said that they might still be there because the trailer was so bad that it could have been condemned. So i went to the trailer park at 8:00 yesterday night and after talking to the neighbors i found out who was in charge of the place. I knocked on his door and told him that the former tenant said I could get something from the trailer. He said that the trailer had been cleaned out. I then told him specifically what I was after, he said give me a minute and then came out. He walked down to the trailer and opened the front door and there they where. All 3 sitting right inside on a counter of a trashed out trailer. He said if you want them go ahead they are yours. He couldn't understand why I wanted those pieces of junk and thanked me for taking them so he did not have to carry them to the trash lol. I loaded them up thanked him. Just think how close these where to the trash can
I first saw them on offer up and the guy wanted $25 for all 3 of them. That was 3 weeks ago. So I messaged him that I would take them but never heard anything back. I kept messaging him at least 2 times a week and yesterday he contacted me. He told me he no longer had them that he had to move quick and had to leave them when he left. That was 2 weeks ago when he moved. I asked him if he thought they might still be where he left them. He sent me the address of a rundown trailer park and said that they might still be there because the trailer was so bad that it could have been condemned. So i went to the trailer park at 8:00 yesterday night and after talking to the neighbors i found out who was in charge of the place. I knocked on his door and told him that the former tenant said I could get something from the trailer. He said that the trailer had been cleaned out. I then told him specifically what I was after, he said give me a minute and then came out. He walked down to the trailer and opened the front door and there they where. All 3 sitting right inside on a counter of a trashed out trailer. He said if you want them go ahead they are yours. He couldn't understand why I wanted those pieces of junk and thanked me for taking them so he did not have to carry them to the trash lol. I loaded them up thanked him. Just think how close these where to the trash can
Cool story. I ended up with my 58 beetle years back in a similar story (barn on a run down property, but otherwise pretty close!) Definitely a good score, and worth the effort to clean up for sure. Personally I would ask the guy if he has an address to receive some cash, I would feel bad taking them for nothing, but it's all good.
I don't feel bad for getting them for free. That guy left them for trash. They sat in a rundown trailer for 2 weeks. I was lucky that they where still there. Also when he found out that I really wanted them all he had to do was go and get them and I would have bought them from him. He was friends with the lady that lived directly across from his trailer, He called her and let her know I was coming, He could have just had her grab them and then sold them to me. He did not care about these at all.
More pics of the back of one. I have never owned a amp like these before so I am not exactly sure how to hook it up. I am sure I need some jumpers in certain places.
25V output would be fine for 70W on 8 Ohm.
Tubes are better than EL34 in Altec 1569a. I like also regulated G2.
Congratulations Don once more!
Tubes are better than EL34 in Altec 1569a. I like also regulated G2.
Congratulations Don once more!
I believe they can be configured for lower load impedances than 25V/70V line applications, but you will need to find the manual online to figure out how to strap the other secondaries.
Do not plug these in! These are in no sense safe or ready for a quick experiment, they need to be cleaned up and coupling caps and most likely all electrolytics replaced. Over the short term you might get away with reforming the electrolytic supply capacitors, but it appears they have probably been stored in a hot, damp Florida warehouse at some point, and I would expect a fair amount of deterioration to have occurred over the years.
The paper in those transformers may be wet as well, might be good to give them some time to dry out.
Do not plug these in! These are in no sense safe or ready for a quick experiment, they need to be cleaned up and coupling caps and most likely all electrolytics replaced. Over the short term you might get away with reforming the electrolytic supply capacitors, but it appears they have probably been stored in a hot, damp Florida warehouse at some point, and I would expect a fair amount of deterioration to have occurred over the years.
The paper in those transformers may be wet as well, might be good to give them some time to dry out.
Hi,
Wow, you are the lucky one. Neat pieces of equipment... I´m little bit envious 😀
73
Wolfgang
Wow, you are the lucky one. Neat pieces of equipment... I´m little bit envious 😀
73
Wolfgang
its kinda like someone throwing you freebie 3x Dyna MKVI (imo your Grommes has a much higher cool factor) or an ARC D150 - which may have some ideas from Hart's creations. Be gentle and slow with the Variac - fuse it too. Were they meant for drive-in theaters?
Thanks to everyone for all the great comments and info. I kind of wish there was a like button at the bottom of each post. I think I should be able to fix one by it's self and then take the 2 left and make one. Each of the other 2 have physical broken parts but different on each. So I will have 2 complete amps when done.
The aim would be to use as many of the separated output windings in parallel as possible - not sure if they are all the same 6.4 or 8.4 ??
Making the bias pot failsafe, and even doubling up the pot to allow bias setting of each side would make sense.
It will be interesting to see how the global feedback, and the doubled up 15Hz low fre RC corners and the 63kHz high final step response RC network work out.
Making the bias pot failsafe, and even doubling up the pot to allow bias setting of each side would make sense.
It will be interesting to see how the global feedback, and the doubled up 15Hz low fre RC corners and the 63kHz high final step response RC network work out.
I found a post on AK that had this small pic from a schematic on the Frazier F-106-c 3 which is the exact same amp with just the Frazier name put on it. It shows the proper hookups for the different ohm settings. Should I use the 1.4 ohm setting to run my Maggies.
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Okay I have been looking on the internet for all the info I can on these. Even though there are not that many of these to compair all of the others I have seen pics of have a different transformer configuration. Mine has 2 real large transformers. All the other ones I see pics of have 3 transformers. But all of those with 3 have 1 very large one just like mine, 1 a little smaller, and then 1 very small that mine does not have. Am I right thinking that mine does not have the 3rd very small one because the second one on mine is much bigger than the second one on all the others? All I know is the 3 I have are a totally different transformer setup than any I have seen. Also from looking at the 3 I have I see no evidence that a 3rd small transformer was ever on any of them. No marks of any kind where they would have been removed.
Mine. I have not found another that has the same transformers is these?
The pic of what all the other ones i see look like.
Mine. I have not found another that has the same transformers is these?
The pic of what all the other ones i see look like.
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