pqrannes
Tubes warm your heart too
I won a Philips OTL (Output TransformerLess) tube amp, AG-9015, from about 1960, off a local auction earlier this winter. It came with a double pair of 800 ohms Philips speakers that fitted the 800 ohms OTL outputs.
I brought the amp up with a number of different lightbulbs (one at a time) in serial with the amp and it play very fine. The sound of the OTL amp and its speakers, and especially the strange little tweeter boxes, is magical although some might miss a deep and tight bass which the non-closed Philips main speaker boxes can’t deliver (there is a lot a bass though from such a little ‘paper’ cabinet. All together I’m very pleased with the ag-9015 which I got for a lot less that they go for on ebay in Germany.
This OTL amp has a pair of non-OTL outputs too, that will let you have the amp drive more ordinary speakers than the 800 ohms Philips. I’ve asked AK’s earlier about matching 4 ohm speakers with the 8 ohm outputs and got god answers.
I then tried my 4 ohm three-way horn speakers on the Philips, but didn’t like the result. And I tried a pair of 8 ohm AR-6 on the Philips, but the outcome wasn’t good this time either.
Then yesterday it was time for trying out my A-25. The immediate result was as bad as with the Jealvox horns and the AR-6s. Since I’m just getting back on my legs after a round of flu my hearing is a bit fuzzy and I gave the A-25 another shot this morning. Not much better. But I didn’t give up. Gave it a try this afternoon … and didn’t it sound just a little bit better? For an hour or two it the setup has been playing and I think – in the aftermath of the flu – that it is not bad at all. It is quite good!
But what happened? The amp has been used daily for about a month now so no turning point there.
My only (poor) explanation is that the non-OTL output section (and the caps there) hasn’t been broken back in without any load on the 8 ohms outputs and only started to sound decent until I started to use it. But is that possible?
I enclose pictures of the amp and speakers (from the auction) and one (bad) nude of the top of the amp showing the two output trannies (I think) and a number of caps next to them.
I know that I might have to recap the output part of the amp to bring it back to its former high end quality but like to hear what ya’ll think of my theory.
Peter, Denmark
I brought the amp up with a number of different lightbulbs (one at a time) in serial with the amp and it play very fine. The sound of the OTL amp and its speakers, and especially the strange little tweeter boxes, is magical although some might miss a deep and tight bass which the non-closed Philips main speaker boxes can’t deliver (there is a lot a bass though from such a little ‘paper’ cabinet. All together I’m very pleased with the ag-9015 which I got for a lot less that they go for on ebay in Germany.
This OTL amp has a pair of non-OTL outputs too, that will let you have the amp drive more ordinary speakers than the 800 ohms Philips. I’ve asked AK’s earlier about matching 4 ohm speakers with the 8 ohm outputs and got god answers.
I then tried my 4 ohm three-way horn speakers on the Philips, but didn’t like the result. And I tried a pair of 8 ohm AR-6 on the Philips, but the outcome wasn’t good this time either.
Then yesterday it was time for trying out my A-25. The immediate result was as bad as with the Jealvox horns and the AR-6s. Since I’m just getting back on my legs after a round of flu my hearing is a bit fuzzy and I gave the A-25 another shot this morning. Not much better. But I didn’t give up. Gave it a try this afternoon … and didn’t it sound just a little bit better? For an hour or two it the setup has been playing and I think – in the aftermath of the flu – that it is not bad at all. It is quite good!
But what happened? The amp has been used daily for about a month now so no turning point there.
My only (poor) explanation is that the non-OTL output section (and the caps there) hasn’t been broken back in without any load on the 8 ohms outputs and only started to sound decent until I started to use it. But is that possible?
I enclose pictures of the amp and speakers (from the auction) and one (bad) nude of the top of the amp showing the two output trannies (I think) and a number of caps next to them.
I know that I might have to recap the output part of the amp to bring it back to its former high end quality but like to hear what ya’ll think of my theory.
Peter, Denmark
