So I am building a set of speakers which use altec 288c compression drivers with 115db of efficiency, and of course getting ahead of myself. These are playing above 500hz so i figured a tube amp would be a great project because I wont have to build a monster!
The speakers are 24 ohms and I own a pair of hammond 1609 output transformers which I would love to use:
http://www.hammondmfg.com/1608.htm
Looks like they recommend push pull, but i have heard good things about single ended designs...
so basically all i am asking is for you to design a tube amp for me! Or point me in a good direction please...
: )
Thanks
BTW stay with this thread, you will not be dissapointed.
The speakers are 24 ohms and I own a pair of hammond 1609 output transformers which I would love to use:
http://www.hammondmfg.com/1608.htm
Looks like they recommend push pull, but i have heard good things about single ended designs...
so basically all i am asking is for you to design a tube amp for me! Or point me in a good direction please...
: )
Thanks
BTW stay with this thread, you will not be dissapointed.
Those transformers would be perfect for a 6V6 push pull ultralinear (PP UL) design. You cannot use them for single-ended, because they are a different design (SE has an air-gap.)
6V6 is the smaller brother of the 6L6- preferred due to its higher power. However, the 6V6 sounds better, and is far cheaper to find NOS as many of them were produced for radio outputs.
You could also use EL84/6BQ5 push-pull.
Have a look at http://www.bonavolta.ch/hobby/en/audio/6v6_2.htm or
http://www.bonavolta.ch/hobby/en/audio/el84_6.htm for examples of simple PP amps
This would probably sound ok. Really you can use just about any PP design for a 6V6 or EL84, they aren't too hard to drive.
Just for a laugh, check this out: 101 6V6s on ebay! (not mine)
eBay
6V6 is the smaller brother of the 6L6- preferred due to its higher power. However, the 6V6 sounds better, and is far cheaper to find NOS as many of them were produced for radio outputs.
You could also use EL84/6BQ5 push-pull.
Have a look at http://www.bonavolta.ch/hobby/en/audio/6v6_2.htm or
http://www.bonavolta.ch/hobby/en/audio/el84_6.htm for examples of simple PP amps
This would probably sound ok. Really you can use just about any PP design for a 6V6 or EL84, they aren't too hard to drive.
Just for a laugh, check this out: 101 6V6s on ebay! (not mine)
eBay
looks good to me, should i bid?!
Imagine a tube driven line array or some high end driver. with a separate amp per speaker, Sweet!
Thanks for the links, more reading!
Imagine a tube driven line array or some high end driver. with a separate amp per speaker, Sweet!
Thanks for the links, more reading!
check out Eli's El Cheapo amp...reference to it here & on the Decware forum. Dhaen also started a thread here on a souped up one.
I'd think best would be a small OPT SE amp using a trioded EL84/6V6...
dave
I'd think best would be a small OPT SE amp using a trioded EL84/6V6...
dave
I would have to pick up different trafos? That isn't too big a deal though then this turns into any number of SE n008 threads on here...
But wait! this one is mine!
thanks for the info guys!
But wait! this one is mine!
thanks for the info guys!
tade said:
In an SE amp a large OPT is required to get good bass... as the size goes up the HF extension decreases (this is a generalization there are lots of other factors), so looking for some tiny EL84 OPTs from an old German hifi would be where i'd be looking (actually i already have a set from a Grundig). Pic is of a set of Nordmende (a bit larger than the Grundigs). The quality of construction is typically very high and they can be found cheap ($20-40/pr in my experience)
Typically thou these are 7-10k into 4 ohms so with your 24 ohm speakers you would have a huge reflected impedance -- but this might let you look at some unusal output tubes... like 12B4, 12BH7 (i don't know what these need but you get the idea). These typically have higher mus -- you might get away with a single stage amp. Add a small coupling cap up front to set the XO frequency and away you go.
dave
Attachments
you know i might actually have a pair of trafos for this very task. unfortunately they are at home so it will be a few weeks till i can get them. Ill keep in touch.
Thanks
Thanks
not the 12B4, even 12BH7 & 12AU7 have Ra lower than needed if you follow the 2.5-3.5x rule of thumb -- at least for the pictured OPTs (you'd want 12-20k Ra for a 24 ohm load)
dave
dave
what is ra? what are the important numbers for an opt?
I think I am getting in over my head! It seems that this is going to be a lot more challenging than i thought!
I think I am getting in over my head! It seems that this is going to be a lot more challenging than i thought!
Ra is the anode resistance, typical rule-of-thumb is to have an OPT with an impedance ratio of 2.5-3.5 x Ra. A higher ration (within limits) means less power with less distortion.
An OPT has a winding ratio that determines the reflected impedance. The example OPT i posted a picture of for instance, has a nominal 10K: 4.5 ohm impedance ratio. If we instead put a 24 ohm driver on this we get a reflected impedance of 24 x 10k/4.5 = 53k
An SE opt also has a DC current limit above which the inductance falls & the bass suffers.
dave
An OPT has a winding ratio that determines the reflected impedance. The example OPT i posted a picture of for instance, has a nominal 10K: 4.5 ohm impedance ratio. If we instead put a 24 ohm driver on this we get a reflected impedance of 24 x 10k/4.5 = 53k
An SE opt also has a DC current limit above which the inductance falls & the bass suffers.
dave
"El Cheapo" project here.
Your Hammond O/P trafos should work. Since you are planning on service >= 500 Hz., you could make the amp. switchable between triode and ultralinear modes. Power handling is increased at higher freqs.; so, UL mode will be fine.
While connecting a 24 Ohm load to the 16 Ohm tap will lower O/P power, it's a non-issue given the HIGH speaker efficiency.
Your Hammond O/P trafos should work. Since you are planning on service >= 500 Hz., you could make the amp. switchable between triode and ultralinear modes. Power handling is increased at higher freqs.; so, UL mode will be fine.
While connecting a 24 Ohm load to the 16 Ohm tap will lower O/P power, it's a non-issue given the HIGH speaker efficiency.
PP vs SE
I have owned both SE & PP power amps. I find when one is used to SE or PP they seem to stay with that design.
So, what are you used to? In most general terms SE has this sweet open midrange & PP is more of a fast dynamic sound per my experience. Either type can be jaw dropping if designed correctly. I do lean on the PP side, but SE removes the issue of having to use very close matched power tubes for best sonics.
SE are dependant upon a very good PS design with a large amount of stored energy in the capacitor that feeds the power tube. Who wants to skimp on a PS anyways.
I believe PP is more forgiving PS wise as it draws more constant current while producing music & has hum canceling due to the PP type design.
Also keep in mind most PP amps have a single-ended preamp tube(s). So, diehard PP audiophiles must like SE to some extent.
I have owned both SE & PP power amps. I find when one is used to SE or PP they seem to stay with that design.
So, what are you used to? In most general terms SE has this sweet open midrange & PP is more of a fast dynamic sound per my experience. Either type can be jaw dropping if designed correctly. I do lean on the PP side, but SE removes the issue of having to use very close matched power tubes for best sonics.
SE are dependant upon a very good PS design with a large amount of stored energy in the capacitor that feeds the power tube. Who wants to skimp on a PS anyways.
I believe PP is more forgiving PS wise as it draws more constant current while producing music & has hum canceling due to the PP type design.
Also keep in mind most PP amps have a single-ended preamp tube(s). So, diehard PP audiophiles must like SE to some extent.
planet ten, thanks for clearing that up. As i learn about electronics it amazes me how dynamic these systems are. The math can be but it usually simple, it is the concepts which stup me at the moment!
Ill keep reading!
Thanks
Ill keep reading!
Thanks
Tade,
I have two amps on the go right now for which the Hammond 1608 or 1609 would be suitable.
One using EL84 (the "Baby Huey" amp) which is posted here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=72536
The other using 6V6 in which I use Hammond 1608s in a unusual fashion in order to apply cathode feedback to the 6V6s. I had to pull a lot of tricks to get this amp anywhere near the performance of the EL84 amp.
The EL84 amp is superior and it is the one I would RECOMMEND.
Cheers,
Ginger
I have two amps on the go right now for which the Hammond 1608 or 1609 would be suitable.
One using EL84 (the "Baby Huey" amp) which is posted here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=72536
The other using 6V6 in which I use Hammond 1608s in a unusual fashion in order to apply cathode feedback to the 6V6s. I had to pull a lot of tricks to get this amp anywhere near the performance of the EL84 amp.
The EL84 amp is superior and it is the one I would RECOMMEND.
Cheers,
Ginger
ok, i am at home and have two old pieces of tube gear at my disposal. One is a really cool radio reciever which worked for about ten minutes then quit. I suppose I should have been more careful about powering it up but I think it was worth it. Not a very good demo for tube sound though. Ill try to fix this piece up when i know more about tube elctronics.
The other piece is something i think i can work with because at some point it was used to drive speakers. I pulled it out of a record player from a yard sale. It took the signal from what was probably a piezo stylus, and played it through two included speakers. There are volume and tone controls. There are three tubes; one is an 12ax7a which i presume was the first gain for the amp? The other two are 50EH5s.
Here is a website with somethinf very similar to what I would like to do:
http://home.att.net/~computer_pro/abraxas/50eh5/50eh5.html
And I would love to end up with something like this:
http://www.geocities.jp/oldrxjp/sakuhin/50EH5-1.jpg
Thanks
The other piece is something i think i can work with because at some point it was used to drive speakers. I pulled it out of a record player from a yard sale. It took the signal from what was probably a piezo stylus, and played it through two included speakers. There are volume and tone controls. There are three tubes; one is an 12ax7a which i presume was the first gain for the amp? The other two are 50EH5s.
Here is a website with somethinf very similar to what I would like to do:
http://home.att.net/~computer_pro/abraxas/50eh5/50eh5.html
And I would love to end up with something like this:
http://www.geocities.jp/oldrxjp/sakuhin/50EH5-1.jpg
Thanks
tade said:
Thanx for that. Jeffery talked to me about a 50EH5 amp, hadn't realized he had one up on the web. I added a link on my 50EH5 amp page. http://www.t-linespeakers.org/tubes/SEP_50EH5.html. There are 2 other amps you missed linked from there.
Do you have a URL for that one... it is quite pretty.
dave
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