Well, I guess its not technically DIY since its a kit, but I have my Bottlehead Paramour 2A3s and Foreplay preamp together and I think they sound really nice through my Fostex 206E backhorns.
I would like to try my hand at a tube phono preamplifier, but I was going to try and break away from the kits for this experiment. I have read and read and read and read the forums and I've seen some phono preamps that look pretty good, but I wanted to see if anyone has encountered a cheap and easy design that they would recommend for a moving magnet cartridge.
Right now I'm running a Hagerman Technologies ultra-super-Cheap-O Bugle Op Amp for my phono pre. I actually think this sounds pretty good, but I really wanted to go all tube.
Any suggestions? Remember-- cheap and easy. Like Mrs. Annan used to be. Hey-- you know I love ya, baby!
Kofi
I would like to try my hand at a tube phono preamplifier, but I was going to try and break away from the kits for this experiment. I have read and read and read and read the forums and I've seen some phono preamps that look pretty good, but I wanted to see if anyone has encountered a cheap and easy design that they would recommend for a moving magnet cartridge.
Right now I'm running a Hagerman Technologies ultra-super-Cheap-O Bugle Op Amp for my phono pre. I actually think this sounds pretty good, but I really wanted to go all tube.
Any suggestions? Remember-- cheap and easy. Like Mrs. Annan used to be. Hey-- you know I love ya, baby!
Kofi
I have built the RCA phono circuit several times with good success. There is a good write up on it on the JE Labs website. On that site Joseph recommends 6SL7s, but I found them to be too microphonic to work with. I've had better success with 12AX7's. One of the things I like about this phono stage is that the RIAA equilization is between two stages and is not in a feedback loop. Other DIY phono stages I've tried are the Curcio replacement for the PAS phono stage, okay, but sounds a bit congested to me; and the phono stage from the Audio Note M7. This is a nice little circuit and easy to build. Overall I think the RCA version is more musical. But YMMV.
Now I will add that I've recently been thinking of taking another run at a phono stage myself. And that is likely going to be the Marantz 7C (you can see it on the Fi Primer site) or a clone of the Fisher X-100 series style. I've heard the Fisher and really liked the sound. The only trouble with using clones of these old stages is that you have to "backwards engineer" it from a schematic that generally includes pretty intricate input selector switch configurations. Once you can trace it out, however, it should be pretty easy.
By the way, layout of this stuff is much more important than a line stage. I'd highly suggest you get a look into the bottom of something like a Fisher integrated and see how they layout the parts and grounding scheme. It is pretty important stuff. This also means you can borrow what others have learned in terms of layout, rather than be disappointed after stuffing in a bunch of expensive parts.
Now I will add that I've recently been thinking of taking another run at a phono stage myself. And that is likely going to be the Marantz 7C (you can see it on the Fi Primer site) or a clone of the Fisher X-100 series style. I've heard the Fisher and really liked the sound. The only trouble with using clones of these old stages is that you have to "backwards engineer" it from a schematic that generally includes pretty intricate input selector switch configurations. Once you can trace it out, however, it should be pretty easy.
By the way, layout of this stuff is much more important than a line stage. I'd highly suggest you get a look into the bottom of something like a Fisher integrated and see how they layout the parts and grounding scheme. It is pretty important stuff. This also means you can borrow what others have learned in terms of layout, rather than be disappointed after stuffing in a bunch of expensive parts.
Hi Guys,
Please be kind enough to post the links to the sites hosting the circuits of the pre-amps described above. I am in the market for a tube pre-amp which preferably used 12AX7s, EF86s or maybe 12AT7, as I have these valves available. I would like a variety of inputs, from phono to CD player.
TIA!
Please be kind enough to post the links to the sites hosting the circuits of the pre-amps described above. I am in the market for a tube pre-amp which preferably used 12AX7s, EF86s or maybe 12AT7, as I have these valves available. I would like a variety of inputs, from phono to CD player.
TIA!
The Fi Primer site is: http://tinpan.fortunecity.com/saints/668/primer/index.html
You should be able to find JE Labs from a Google.
Audio Note M7 here: http://www.drtube.com/audioamp.htm#AN
(also others like Conrad Johnson and HK Citation).
Scott here: http://hhscott.com/database/vhhs_00011.html
Fisher here: http://oldtech.net/Fisher.html
The X-101 C is the one I'm most interested in right now. Though you'll find a couple of errors there - a 22m resistor should be 2.2m and a 22k resistor should be 2.2k (cathod of the V1 vs. V2, and grid of V1 vs V2).
As for internal layouts, do some searching on ebay and you'll often find photos of the insides of old equipment. With a bit of luck you'll find one with enough clarity that you can figure out the general idea. Another source of info on layouts is to get the manuals for some kits, like a Heath AA-151, which has a pretty neat and orderly chassis layout including a buss bar grounding scheme.
Happy building!
You should be able to find JE Labs from a Google.
Audio Note M7 here: http://www.drtube.com/audioamp.htm#AN
(also others like Conrad Johnson and HK Citation).
Scott here: http://hhscott.com/database/vhhs_00011.html
Fisher here: http://oldtech.net/Fisher.html
The X-101 C is the one I'm most interested in right now. Though you'll find a couple of errors there - a 22m resistor should be 2.2m and a 22k resistor should be 2.2k (cathod of the V1 vs. V2, and grid of V1 vs V2).
As for internal layouts, do some searching on ebay and you'll often find photos of the insides of old equipment. With a bit of luck you'll find one with enough clarity that you can figure out the general idea. Another source of info on layouts is to get the manuals for some kits, like a Heath AA-151, which has a pretty neat and orderly chassis layout including a buss bar grounding scheme.
Happy building!
Look for post #10 in the thread "dc phono", similar topology to the RCA circuit with 2nd stage using 6DJ8/ECC88 which has lower plate impedance for better output drive and grid leak bias for better LF response, also has 2nd stage input coupling capacitor after the RIAA eq network for DC on the eq caps which may improve sonic character. I want to build the "dc phono" myself but need to find time to do it.
I built the RCA circuit in the early 80's and the high output impedance didn't work well with my SS line stage at that time, if I were to try it again I would use 6072/12AY7 instead of 12AX7, lower gain but also lower noise, lower plate impedance, and less competition for quality NOS tubes, but the values of plate resistors and the 470k eq network resistor would have to be changed.
Another option is to buy the Bottlehead Seduction preamp kit for US$279 but special arrangements are needed for orders outside US and Canada.
The SP-6 clone which uses active RIAA eq would probably sound great (to me, anyway) but is more complicated than the "dc phono" thread or the RCA. Active RIAA eq seems to be out of fashion today anyway due to feedback affecting sonic character, and is more difficult to design for due to the eq accuracy being affected by the limited open loop gain available from two resistive-loaded triodes, one or both stages can be cascoded with more complexity..... Passive eq is simpler to design but eq network source and load impedances must be considered for best eq accuracy. I have tinkered with the Dyna PAS phono which is an active EQ design without output follower and HF extension is weak even into a high impedance load, OK if you like a "soft" sound.
I built the RCA circuit in the early 80's and the high output impedance didn't work well with my SS line stage at that time, if I were to try it again I would use 6072/12AY7 instead of 12AX7, lower gain but also lower noise, lower plate impedance, and less competition for quality NOS tubes, but the values of plate resistors and the 470k eq network resistor would have to be changed.
Another option is to buy the Bottlehead Seduction preamp kit for US$279 but special arrangements are needed for orders outside US and Canada.
The SP-6 clone which uses active RIAA eq would probably sound great (to me, anyway) but is more complicated than the "dc phono" thread or the RCA. Active RIAA eq seems to be out of fashion today anyway due to feedback affecting sonic character, and is more difficult to design for due to the eq accuracy being affected by the limited open loop gain available from two resistive-loaded triodes, one or both stages can be cascoded with more complexity..... Passive eq is simpler to design but eq network source and load impedances must be considered for best eq accuracy. I have tinkered with the Dyna PAS phono which is an active EQ design without output follower and HF extension is weak even into a high impedance load, OK if you like a "soft" sound.
Good idea. Cloning AR you can't go too wrong. At the time i cloned SP3, Sp6 and Sp10 and although none provided the exact sound i was looking for i could easily live with any of them. The Sp10 in particular impressed me with tremendous macro dynamics, great bass and amazing soundstage. Admittedly it had some weaknesses but the redeeming features were too many.
Thanks for all the responses!
I need to have this dumbed down a bit. I don't have that much experience with tube amps. Plus, I'm dumb.
Has anyone tried this phono preamp? It looks fairly simple (based on the RCA preamp). Can anyone point me to a power supply schematic for it (if its worth doing)?
Thanks,
Kofi
I need to have this dumbed down a bit. I don't have that much experience with tube amps. Plus, I'm dumb.
Has anyone tried this phono preamp? It looks fairly simple (based on the RCA preamp). Can anyone point me to a power supply schematic for it (if its worth doing)?
Thanks,
Kofi
Kofi Annan said:
Twice as many sections as the RCA one i posted (i haven't heard this one). If i was building a single-ended phono i'd probablt tackle this one:
An externally hosted image should be here but it was not working when we last tested it.
from Vacuum State web site.
You'd only need the 1st stage, but depending on what follows & how close you might need the follower stage. Some schema from earlier versions there too.
dave
OK, because I'm pretty green, can you recommend a regulated / well-filtered PSU for this (schematics would be much appreciated)?
Does the phono stage end at the grounded 1m resisitor and, if so, does that become the lead out?
My line stage will be the Bottlehead Foreplay. Anyone have any experience with this line stage and the proposed phono stage?
As you can see, I'm asking some pretty basic / dumb questions. I really appreciate all the responses-- I'm hoping to make this my first foray into non-kit tube amp building.
Thanks!
Kofi
Does the phono stage end at the grounded 1m resisitor and, if so, does that become the lead out?
My line stage will be the Bottlehead Foreplay. Anyone have any experience with this line stage and the proposed phono stage?
As you can see, I'm asking some pretty basic / dumb questions. I really appreciate all the responses-- I'm hoping to make this my first foray into non-kit tube amp building.
Thanks!
Kofi
Hi,
At the grounded 1M resistor, right before the selector switch.
What follows after that however is of the utmost importance to maintain accuracy of the RIAA correction curve as is stated on a note in the pic regarding the 50K pot.
Combining this phono stage with the Foreplay preamp would require it to have an input impedance of 50K (pot or constant impedance attenuator can do).
Brett already mentioned this in the previous post.
No idea what the Foreplay has for values there so check the manual for this info.
If it were to me building the preamp I'd build it as shown and put the Foreplay aside for the time being.
IMO the best way to proceed would be to order a Superreg (maybe two are needed?) for this pre as I don't think this part was released to the public.
Other than that I could post a link a 250 VDC series reg'ed supply, I have no idea how the two would combine sonically though. You'd need one per channel too, which is the better approach anyway...
Hope this helps,
At the grounded 1M resistor, right before the selector switch.
What follows after that however is of the utmost importance to maintain accuracy of the RIAA correction curve as is stated on a note in the pic regarding the 50K pot.
Combining this phono stage with the Foreplay preamp would require it to have an input impedance of 50K (pot or constant impedance attenuator can do).
Brett already mentioned this in the previous post.
No idea what the Foreplay has for values there so check the manual for this info.
If it were to me building the preamp I'd build it as shown and put the Foreplay aside for the time being.
IMO the best way to proceed would be to order a Superreg (maybe two are needed?) for this pre as I don't think this part was released to the public.
Other than that I could post a link a 250 VDC series reg'ed supply, I have no idea how the two would combine sonically though. You'd need one per channel too, which is the better approach anyway...
Hope this helps,
fdegrove said:
The line stage in the FVP is at least a bit better for sure...
You can buy the preamp cookbook and he tells you all about it. the reg is quite layout sensitive, so to my mnd ordering the kit, so that you don't have to debug an occilator is a no-brainer. With adequate heat sinking 1 super reg will supply up to 750 mA, so 1 will do.
dave
Konnichiwa,
I still think in your context the Bottlehead Seduction Kit would likely be a good choice, especially based on reviewing the thread.
Something that is a known quantity, very easy to copy DIY and usually very easy to get to work well is the EAR 834P. Here some links to EAR based DIY Projects:
http://www.jogis-roehrenbude.de/Leserbriefe/Carsten-RIAA/Carsten-RIAA.htm
http://www.jogis-roehrenbude.de/Leserbriefe/Doellmann-RIAA/Doellmann-RIAA.htm
I have attached the original EAR schematic which has been published repeatedly (IIRC this one came from HiFi-News).
Stereophile put the EAR into "Class B" and note it narrowly misses Class A. It does so because TdP's philosophy is to ue the cheapest, commonenst and nastiest components on the block to make his Amp's (Audio Transformers excluded). Which mean if you up the ante a little you can have an excellent Preamp.
Other than that I would recommend the Phonostage Design I presented previously as the "Valve El Cheapo"....
The whole DC Phono Thread contains a pretty extensive discussion of the why and many hint's on how to realise the circuit:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=28957&perpage=10&highlight=&pagenumber=1
Build it using a passive RC filtered supply as detailed below (simple RC filtered supplies are really hard to louse up):
http://www.diyaudio.com/forums/attachment.php?s=&postid=343849
Someone build the Phonostage recently and had a few good things to say:
http://www.diyaudio.com/forums/showthread.php?postid=349613#post349613
I hope this helps.
Sayonara
Kofi Annan said:
I still think in your context the Bottlehead Seduction Kit would likely be a good choice, especially based on reviewing the thread.
Kofi Annan said:
Something that is a known quantity, very easy to copy DIY and usually very easy to get to work well is the EAR 834P. Here some links to EAR based DIY Projects:
http://www.jogis-roehrenbude.de/Leserbriefe/Carsten-RIAA/Carsten-RIAA.htm
http://www.jogis-roehrenbude.de/Leserbriefe/Doellmann-RIAA/Doellmann-RIAA.htm
I have attached the original EAR schematic which has been published repeatedly (IIRC this one came from HiFi-News).
Stereophile put the EAR into "Class B" and note it narrowly misses Class A. It does so because TdP's philosophy is to ue the cheapest, commonenst and nastiest components on the block to make his Amp's (Audio Transformers excluded). Which mean if you up the ante a little you can have an excellent Preamp.
Other than that I would recommend the Phonostage Design I presented previously as the "Valve El Cheapo"....
The whole DC Phono Thread contains a pretty extensive discussion of the why and many hint's on how to realise the circuit:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=28957&perpage=10&highlight=&pagenumber=1
Build it using a passive RC filtered supply as detailed below (simple RC filtered supplies are really hard to louse up):
http://www.diyaudio.com/forums/attachment.php?s=&postid=343849
Someone build the Phonostage recently and had a few good things to say:
http://www.diyaudio.com/forums/showthread.php?postid=349613#post349613
I hope this helps.
Sayonara
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.