Does anyone have any opinions (ha, that's a silly way to start this question, isn't it?) on the use of Aikido preamps with Gainclone amps?
Long story short, I need to downsize my living room setup and I've been burning to try both of these designs for some time. I'd like to put both the GC and Aikido in the same enclosure (approx 12" x x 8"), so space is somewhat of an issue. Reading through the documentation, I'm confident with my ability to construct these designs, though I may need advice in picking out ACF values/tubes if going that direction.
Any experience with Aikido designs feeding a Gainclone here? Would it be better to go with the buffer ACF-2 or the preamp 12VAC. I will be playing mostly vinyl through this system (with an appropriate phono pre, of course).
Long story short, I need to downsize my living room setup and I've been burning to try both of these designs for some time. I'd like to put both the GC and Aikido in the same enclosure (approx 12" x x 8"), so space is somewhat of an issue. Reading through the documentation, I'm confident with my ability to construct these designs, though I may need advice in picking out ACF values/tubes if going that direction.
Any experience with Aikido designs feeding a Gainclone here? Would it be better to go with the buffer ACF-2 or the preamp 12VAC. I will be playing mostly vinyl through this system (with an appropriate phono pre, of course).
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ACF-2 Buffer, I had the same problem, I built the Aikido 9-Pin All In One and I built an AudioSector LM4780.
Problem is that the LM4780 design has all the gain you need built in.
So.....What you really need is a buffer.
My Aikido with my LM4780 has WAAAAAYY too much gain.
Go with 6SN7's and the factory values that John recommends in the build manual, it will work very well I'm sure.
Problem is that the LM4780 design has all the gain you need built in.
So.....What you really need is a buffer.
My Aikido with my LM4780 has WAAAAAYY too much gain.
Go with 6SN7's and the factory values that John recommends in the build manual, it will work very well I'm sure.
Thanks, Einric! Reading through Gainclone posts, I suspected that may be the case.
The ACF-2 board is a little larger, and it requires a transformer, but I'm sure I can make do. Looks like JB recommends an Edcor here, which will save some space inside the enclosure vs a toroidal with the 12VAC.
Unfortunately, the ACF-2 board is out of stock and the link to the ACF pdf manual is busted. Anyone know if JB is still producing this kit?
The ACF-2 board is a little larger, and it requires a transformer, but I'm sure I can make do. Looks like JB recommends an Edcor here, which will save some space inside the enclosure vs a toroidal with the 12VAC.
Unfortunately, the ACF-2 board is out of stock and the link to the ACF pdf manual is busted. Anyone know if JB is still producing this kit?
Hmm, did some more research after seeing the ACF2 is out of stock and I'm reconsidering the 12VAC and thinking 3886 instead of 3875 (supposedly more stable into 4 ohms?).
For one thing, it's available; for another, it's a simple and fairly small preamp that I might want to use elsewhere in my DIY adventures.
So here's the slightly modified proposal:
-Go with a chipamp.com LM3886 kit and set the gain fairly low (maybe R3 of 1.5k for 15db?)
-Stick with the Aikido 12VAC, 6DJ8 for gain of 15db
-Total gain of 30db
Any thoughts? Warnings?
For one thing, it's available; for another, it's a simple and fairly small preamp that I might want to use elsewhere in my DIY adventures.
So here's the slightly modified proposal:
-Go with a chipamp.com LM3886 kit and set the gain fairly low (maybe R3 of 1.5k for 15db?)
-Stick with the Aikido 12VAC, 6DJ8 for gain of 15db
-Total gain of 30db
Any thoughts? Warnings?
See Decibel Dungeon for inverting mode gainclones that can be set for lower gain.
The Decibel Dungeon Gainclone index page with links to all chip amp articles.
The stability is high on both the t-network and ordinary inverting designs, and that's just the sort of thing that you can set to lower gain.
Also the TDA7293 has a power buffer (aka "slave") mode that disables its internal voltage amp: http://www.diyaudio.com/forums/chip-amps/197398-tda7293-single-bridge-parallel-3.html In that way it may be possible to do Aikido with Fet (tda7293) outputs. However, it is possible that discrete parts output buffer might be easier. Surely someone has published an Aikido hybrid already?
The Decibel Dungeon Gainclone index page with links to all chip amp articles.
The stability is high on both the t-network and ordinary inverting designs, and that's just the sort of thing that you can set to lower gain.
Also the TDA7293 has a power buffer (aka "slave") mode that disables its internal voltage amp: http://www.diyaudio.com/forums/chip-amps/197398-tda7293-single-bridge-parallel-3.html In that way it may be possible to do Aikido with Fet (tda7293) outputs. However, it is possible that discrete parts output buffer might be easier. Surely someone has published an Aikido hybrid already?
Hi Daniel-
Thank you for the info. I haven't seen any Aikido hybrids around the net, but maybe someone else chimes in? There were some Tubecad articles that touched on it, but they're so far over my head that I decided to ask here as well.
I'm open to ideas about how to tackle the post-Aikido portion of this project. The chassis I have to work with is very small (12" x 8") though and that's what lead me down the chipamp path.
I realize this is probably a very basic question, but could anyone briefly explain the hypothetical advantage of having the Aikido handle the voltage gain and the chip handle the current gain (hopefully I have that straight)? Is it just playing off the strengths of tubes vs chips?
Thank you for the info. I haven't seen any Aikido hybrids around the net, but maybe someone else chimes in? There were some Tubecad articles that touched on it, but they're so far over my head that I decided to ask here as well.
I'm open to ideas about how to tackle the post-Aikido portion of this project. The chassis I have to work with is very small (12" x 8") though and that's what lead me down the chipamp path.
I realize this is probably a very basic question, but could anyone briefly explain the hypothetical advantage of having the Aikido handle the voltage gain and the chip handle the current gain (hopefully I have that straight)? Is it just playing off the strengths of tubes vs chips?
My Aikido Drives a DIY store F4 and it is phenomenal.
In my application the F4 provides FAR superior experience across the board V.S. my LM4780 Parallel amp.
I understand this is apples and oranges, but If I could find a way to lower my 4780 gain I would.
However the idea of having a tube "front end" with a chip "output" is a great idea that the TDA7293 may be able to pull off for you.
Daniel probably has a picture of the 7293 on perfboard for P2P wiring.
This would make for a pretty straight forward application.
12x8 will barely be big enough since your transformer will take up 50% of your useable 8".
This will lead to the possibility of HUMMMMM that everybody hates.
In my application the F4 provides FAR superior experience across the board V.S. my LM4780 Parallel amp.
I understand this is apples and oranges, but If I could find a way to lower my 4780 gain I would.
However the idea of having a tube "front end" with a chip "output" is a great idea that the TDA7293 may be able to pull off for you.
Daniel probably has a picture of the 7293 on perfboard for P2P wiring.
This would make for a pretty straight forward application.
12x8 will barely be big enough since your transformer will take up 50% of your useable 8".
This will lead to the possibility of HUMMMMM that everybody hates.
After reading about the 41hz and GC amps, it's become fairly clear that something like the F4 is what I really should be building with the Aikido 12VAC (ie voltage follower buffer). Of course, that's going to be too big for my enclosure (and my wife's tastes)!
I'm going to have to either wait for the ACF2 to come back into stock, build the original ACF with a separate power supply (pushing size constraints again), or give up integrating a tube pre into this project. Sigh, nothing ever comes easy in DIY audio, does it?
I'm going to have to either wait for the ACF2 to come back into stock, build the original ACF with a separate power supply (pushing size constraints again), or give up integrating a tube pre into this project. Sigh, nothing ever comes easy in DIY audio, does it?
The only thing I can think of is to look at this: Tube Gainclone for DIY Buffs And then ask Joe Rasmussen.
Nice find, Daniel! Looks very promising and I will read through it.
At first glance, it appears that the LM3875 in the schematic is at 26db gain (before what's added by the 6922). Wouldn't this not be much different than running the 3886 kit at lower gain, say around 15db, and using the Aikido 12VAC kit to drive it at around another 15db for a total of 30db?
I'm open to PTP wiring from a schematic, but the tinkerer in me says boards will be easier to swap and play with in the future
Edit: Ah, nevermind. I read through the article and looks like the 6922 is used as a unity gain buffer, like the ACF (not the 12VAC).
At first glance, it appears that the LM3875 in the schematic is at 26db gain (before what's added by the 6922). Wouldn't this not be much different than running the 3886 kit at lower gain, say around 15db, and using the Aikido 12VAC kit to drive it at around another 15db for a total of 30db?
I'm open to PTP wiring from a schematic, but the tinkerer in me says boards will be easier to swap and play with in the future
Edit: Ah, nevermind. I read through the article and looks like the 6922 is used as a unity gain buffer, like the ACF (not the 12VAC).
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MrWagner-
I saw the same thing. This lead me to wonder whether I could use the gain of the Aikido 12VAC with a 3886/3875 run with lower gain (I believe this is set by a resistor ratio in Audio Sector and Chipamp.com kits). In total, it would not be difficult to achieve a net gain of 30db or so.
I'm really not qualified enough to say whether there is something inherently bad about this idea though. Is it always preferable to relegate the gain to one stage (with the other as a buffer) in this situation? Is there a reason to not run chip amps at lower gain? The end result, in terms of power, would be the same, wouldn't it? I may be missing something.
I saw the same thing. This lead me to wonder whether I could use the gain of the Aikido 12VAC with a 3886/3875 run with lower gain (I believe this is set by a resistor ratio in Audio Sector and Chipamp.com kits). In total, it would not be difficult to achieve a net gain of 30db or so.
I'm really not qualified enough to say whether there is something inherently bad about this idea though. Is it always preferable to relegate the gain to one stage (with the other as a buffer) in this situation? Is there a reason to not run chip amps at lower gain? The end result, in terms of power, would be the same, wouldn't it? I may be missing something.
I don't know about the Audio Sector kit so can't comment, the chipamp.com LM3886 kit i'm building has the gain set by varying R3 using the equation, Gain = 1 + RF/R3 the standard gain is set at 33dB. The manual says gain should be kept above 10dB to reduce the chance of the amp going into oscillation.
Increasing the value of R3 lowers the gain.
I see no problem with trying a few values to see which gives you the best sound and volume adjustment, you don't want to achieve full volume with only 20 degrees of volume pot rotation.
Increasing the value of R3 lowers the gain.
I see no problem with trying a few values to see which gives you the best sound and volume adjustment, you don't want to achieve full volume with only 20 degrees of volume pot rotation.
Go with that thought!!! It will serve you very well.
What experience do I have to say this? I've built LM3875, LM3886, F4, F5, F5T, Aleph J.
Build an F4 and an Aikido. I know you are looking to make something small... Forget that and build the F4.
Not to beat a dead horse but a fan cooled F4 can be made pretty small (Small For Pass Design).
With some clever building skills you could integrate the F4 and Aikido into a single chassis.
You'd just need a On Delay relay set to 30Sec. to allow the Aikido time to warm up before the F4 gets the sauce.
Then you'd have something quite special, 6DJ8's in Aikido will drive the F4 to clipping with the proper setup.
Tubes out the top and MosFET Sinks on the sides.
A similar thing probably could be done as Daniel suggested with the TDA7293 in "Slave Mode".
The nice thing about TDA7293 in slave mode is that you could parallel 2 or 3 of them per side for some serious power output into lower Ω's.
With some clever building skills you could integrate the F4 and Aikido into a single chassis.
You'd just need a On Delay relay set to 30Sec. to allow the Aikido time to warm up before the F4 gets the sauce.
Then you'd have something quite special, 6DJ8's in Aikido will drive the F4 to clipping with the proper setup.
Tubes out the top and MosFET Sinks on the sides.
A similar thing probably could be done as Daniel suggested with the TDA7293 in "Slave Mode".
The nice thing about TDA7293 in slave mode is that you could parallel 2 or 3 of them per side for some serious power output into lower Ω's.
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6L6, Einric-
What kind of size are you thinking would be possible? I have an enclosure that I bought quite a while ago just because it looks cool. It's 12w x 8d x 2h with aluminum front/back/top/bottom and walnut sides. It's a looker and so I'm trying to incorporate it in some way.
The design I'm looking for is constrained by the size of the credenza it will sit on along with my turntable (in the living room so WAF is important). How much heat does an F4 produce? Could this possibly be put inside of the credenza (doors on the front) with the preamp section sitting on top of it? That would allow me to keep the preamp/control portion on top in the open, with the power section hidden away inside. If heat isn't a big factor, that would give me plenty of real estate.
BTW, 6L6, your builds are awesome and I think I've looked through all of them.
What kind of size are you thinking would be possible? I have an enclosure that I bought quite a while ago just because it looks cool. It's 12w x 8d x 2h with aluminum front/back/top/bottom and walnut sides. It's a looker and so I'm trying to incorporate it in some way.
The design I'm looking for is constrained by the size of the credenza it will sit on along with my turntable (in the living room so WAF is important). How much heat does an F4 produce? Could this possibly be put inside of the credenza (doors on the front) with the preamp section sitting on top of it? That would allow me to keep the preamp/control portion on top in the open, with the power section hidden away inside. If heat isn't a big factor, that would give me plenty of real estate.
BTW, 6L6, your builds are awesome and I think I've looked through all of them.
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I'm running an Aikido 9 pin all in one with an F5 and it's very nice. Easily outperforms the chipamps that I've built (chipamp.com 3886, MyRefC). The F5 is also very easiy to build and shouldn't cost that much more than a chip amp. It is a bit larger though. I recommend building the Aikido in a separate enclosure, it gives you more options for other amps to try in the future. Very nice preamp.
PJN
PJN
PJN
I think I'm now leaning towards separate Aikido and power amp. I was a little too optimistic with what I could pull off in the single enclosure. I imagine that if I built a gainclone, I'd end up feeling underwhelmed or limited by the output. I'm intrigued reading through some of the Pass Labs info. Is there a single source for PCBs or kits?
Edit: Wow, I've never seen the DIY Audio store before! Has this always been here?!
I think I'm now leaning towards separate Aikido and power amp. I was a little too optimistic with what I could pull off in the single enclosure. I imagine that if I built a gainclone, I'd end up feeling underwhelmed or limited by the output. I'm intrigued reading through some of the Pass Labs info. Is there a single source for PCBs or kits?
Edit: Wow, I've never seen the DIY Audio store before! Has this always been here?!
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