Klimon said:
Sure, it only has 1 watt output per channel. Look at Hammond type 125ASE in http://www.hammondmfg.com/125SE.htm - at 3 watts it's not much bigger than the transformers shown in the picture.
The caveats for running a 6AU6 as a triode with grounded plate and grid 2 acting as the sole anode are:
1. Don't exceed the maximum grid 2 dissipation of 650 mw, and
2. Only use it with small signals, e.g. in a preamp, to avoid poor linearity.
I used it successfully like this in a preamp stage following a James-type tone stack, which has an attenuation factor of 12dB, thus the signal was very small.
1. Don't exceed the maximum grid 2 dissipation of 650 mw, and
2. Only use it with small signals, e.g. in a preamp, to avoid poor linearity.
I used it successfully like this in a preamp stage following a James-type tone stack, which has an attenuation factor of 12dB, thus the signal was very small.
I'll recommend the 3A5 - cheapest good sounding DHT, and a double at that. I bought 100 really cheap - they're slightly bright but very detailed and have that genuine DHT sound. You need a good filament supply as always with DHTs. I use them in diff pairs to reduce mcrophonics, and put a couple of cheap plumbers rubber rings on each. Definitely one to try out for peanuts, since the really good DHTs are getting scarce and going up in price.
the problem with this thread is that you worry may be you havent got enough before the prices go north...
or is that me?
letting the cat out what about the ec91? this will, at the moment, be my input stage. Unless its the 6AT6
and If I might be a little bold I didnt think the 6AU7 was that special from the plate curves. Am I missing something? - The triode curves are the first place I look no-matter-what If they arent evenly spaced then
And it didn't make my list.
should we (I) consider other factors? but for me if there's not good intrinsic linearity then consider something else. this is why the *sn7 are so well regarded, and the 300B (OK I have to admit it curves nice...)
Andy
or is that me?
letting the cat out what about the ec91? this will, at the moment, be my input stage. Unless its the 6AT6
and If I might be a little bold I didnt think the 6AU7 was that special from the plate curves. Am I missing something? - The triode curves are the first place I look no-matter-what If they arent evenly spaced then
And it didn't make my list.should we (I) consider other factors? but for me if there's not good intrinsic linearity then consider something else. this is why the *sn7 are so well regarded, and the 300B (OK I have to admit it curves nice...)
Andy
NFB is poison. Besides, now we're down 1dB at 25Hz. Big deal.
I have iron on my bench right now that is down less than 1dB (ref 1KHz) at less than 10Hz. These from Mikey (MQ), and my Thai pal Kittipol at SACThailand.
C'mon, guys, we're supposed to be pushing the envelope here, not promoting mediocricity. Everybody here has already seen mediocracy.
I lurk here to get eddjakated. C'mon,eddjakate me.
Aloha,
Poinz
I have iron on my bench right now that is down less than 1dB (ref 1KHz) at less than 10Hz. These from Mikey (MQ), and my Thai pal Kittipol at SACThailand.
C'mon, guys, we're supposed to be pushing the envelope here, not promoting mediocricity. Everybody here has already seen mediocracy.
I lurk here to get eddjakated. C'mon,eddjakate me.
Aloha,
Poinz
Poindexter said:
*shrug* I'm just pointing out the transformers on the impamp aren't unreasonably small by comparing them with existing stock.
Besides, I have a few envelope-expanders in construction here, but I won't mention them until such time as they're ready for public consumption. Suffice it to say prototype tests are not unpromising, although the cats run and hide when I crank up some full power runs.
Jeez,
Sorry about the tone of that post; it came out a lot harsher than I thought. I thought we were going to be talking about cool undiscovered devices, but it seems to have wandered a bit.
Another one I'm looking at right now is the 6T4, a lowish mu single triode. I want to replace the 6AQ5 in the preamp with it (or something) if possible because I have to select the power tubes so carefully for microphonics in the low signal application. The 6T4 has chars very much like the 6AQ5 (rp=2K, S=5.5, mu=11), only it's a lower power device (3.5W), uses a lot less heater, is about half the physical size (which is sort of a marketing disadvantage, actually), and they turn out to be pretty much completely unmicrophonic.
All is not completely well in duckburg, in the breadboard they're okay but not great, a little creamy and bland. I'll be fooling with the OP and load, maybe they'll wake up. Available; Jack was glad to scare me up a hundred RCAs from his stash, cheap.
Further research seems indicated, doesn't it always?
Aloha,
Poinz
Sorry about the tone of that post; it came out a lot harsher than I thought. I thought we were going to be talking about cool undiscovered devices, but it seems to have wandered a bit.
Another one I'm looking at right now is the 6T4, a lowish mu single triode. I want to replace the 6AQ5 in the preamp with it (or something) if possible because I have to select the power tubes so carefully for microphonics in the low signal application. The 6T4 has chars very much like the 6AQ5 (rp=2K, S=5.5, mu=11), only it's a lower power device (3.5W), uses a lot less heater, is about half the physical size (which is sort of a marketing disadvantage, actually), and they turn out to be pretty much completely unmicrophonic.
All is not completely well in duckburg, in the breadboard they're okay but not great, a little creamy and bland. I'll be fooling with the OP and load, maybe they'll wake up. Available; Jack was glad to scare me up a hundred RCAs from his stash, cheap.
Further research seems indicated, doesn't it always?
Aloha,
Poinz
The Machine isn't SET, but it's all triode, zero NFB, and takes a pretty high load on the outputs as well, 8-10K. Last one I made for a client had 10K Silk outputs and 0.33uF Mundorf Silver/Oils, and was down 1dB at 10Hz and 39KHz.
Since the grid circuit resistors on the outputs are 100K, this will define the -3dB point of delivery of signal to the outputs at 4.7Hz, so who knows where the inductance of the OT actually falls off? Now, these are PP trannies, and presumably very lightly gapped if at all, but it certainly points out the doability of the solution.
That guy sure has a cool thing in that handfull of amp though, if it sounds like anything at all.
Aloha,
Poinz
Since the grid circuit resistors on the outputs are 100K, this will define the -3dB point of delivery of signal to the outputs at 4.7Hz, so who knows where the inductance of the OT actually falls off? Now, these are PP trannies, and presumably very lightly gapped if at all, but it certainly points out the doability of the solution.
That guy sure has a cool thing in that handfull of amp though, if it sounds like anything at all.
Aloha,
Poinz
Poindexter said:
WHOA! Not to thread-jack, but 5965? interesting choice. i have only seen them DIY-ed in studio compressors and whatnot because of the cutoff charactaristic. I have always wanted to tinker with remote cutoff triodes at bend the transfer function a bit to see what kind of interesting harmonic spectrum I could milk from it...
