Hi
I am thinking about building a stereo power amp. I have a pair of JM Lab Focal floor standing speaker. I only have a SS Acurus 200W amp that is totally not up to par. I cannot afford to spend $3000 to $5000 for an amp, I have experience in designing and building a few guitar tube amps already but I have never even touch a hifi amp, not to mention one at the price range I want. I am hoping to build one as a hobby and save money. Please give me suggestion and maybe schematic of what I am looking for.
Thanks
I am thinking about building a stereo power amp. I have a pair of JM Lab Focal floor standing speaker. I only have a SS Acurus 200W amp that is totally not up to par. I cannot afford to spend $3000 to $5000 for an amp, I have experience in designing and building a few guitar tube amps already but I have never even touch a hifi amp, not to mention one at the price range I want. I am hoping to build one as a hobby and save money. Please give me suggestion and maybe schematic of what I am looking for.
Thanks
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Here is a stereo amp project that does anywhere from 18 Watts to 250 Watts. Long, but interesting thread. Inexpensive, well liked.
http://www.diyaudio.com/forums/tubes-valves/151206-posted-new-p-p-power-amp-design.html
http://www.diyaudio.com/forums/tubes-valves/151206-posted-new-p-p-power-amp-design.html
Alan,
Assuming you have Focal 714s or something similar, considerable power will be needed. Don't be fooled by OEM claims. Notice the almost 50% impedance dip, as well as the 91 dB. sensitivity. When mated to a tube amp, those speakers should be connected to the 4 Ohm taps and the sensitivity derated to 88 dB.
Apply Paul Joppa's 102 dB. rule to the situation and you come up with at least 30 WPC. The tubes to look at are: 7591, EL34/6CA7, and 6L6. "Cloning" the Harman/Kardon Citation V, which employs Mullard style circuitry, is a definite possibility. Edcor's CXPP100-MS-6.6K O/P trafo seems suitable.
Assuming you have Focal 714s or something similar, considerable power will be needed. Don't be fooled by OEM claims. Notice the almost 50% impedance dip, as well as the 91 dB. sensitivity. When mated to a tube amp, those speakers should be connected to the 4 Ohm taps and the sensitivity derated to 88 dB.
Apply Paul Joppa's 102 dB. rule to the situation and you come up with at least 30 WPC. The tubes to look at are: 7591, EL34/6CA7, and 6L6. "Cloning" the Harman/Kardon Citation V, which employs Mullard style circuitry, is a definite possibility. Edcor's CXPP100-MS-6.6K O/P trafo seems suitable.
If that's the 716, then they should work quite well with an "uprated" version of Pete's DCPP amp in an average size room.
jeff
I recommend that before you commit on a big and expensive build (power is expensive, if fidelity is required), you make a small power amp maybe on a breadboard and try it out. You can use that amp as your preamp section later on. Anyway it will provide you with valuable information about your actual power requirements.
Thanks everybody. I am absolutely green in hifi arena, I am sure my OP must sound very ignorant. I just look at the exact model of my speaker the first time, the model is "Spectral 913.1", it is 250W, 4ohm. It has two 8" woofer, a 5"mid and a reverse dome tweeter.
I only want to build a power amp, I am thinking about using a schematic of a known amp like Cary or other brand that I don't even know of, to build an exact copy of the amp.
I know I should build a cheaper and smaller power amp as a practice run. I did design and built a few Guitar tube amp, I wonder whether I can skip the learning step and go for the ultimate one since I am not planning to be adventurous and experiment with mods? From the experience of guitar amps, I know there is so many intricate knowledge that it takes a long time to master. So I am planning to straight copy as I am more interested in getting a better amp for listening.
Thanks for all your time.
I only want to build a power amp, I am thinking about using a schematic of a known amp like Cary or other brand that I don't even know of, to build an exact copy of the amp.
I know I should build a cheaper and smaller power amp as a practice run. I did design and built a few Guitar tube amp, I wonder whether I can skip the learning step and go for the ultimate one since I am not planning to be adventurous and experiment with mods? From the experience of guitar amps, I know there is so many intricate knowledge that it takes a long time to master. So I am planning to straight copy as I am more interested in getting a better amp for listening.
Thanks for all your time.
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If you just want an amp, not the construction experience, you'll be much better off and more likely to be happy
with the result if you buy a used amplifier that is suitable for your speakers. You can't just copy a commercial amp and turn it on.
Lots of factors. The exact PCB layout is important, and can even be critical. Semiconductor devices may need to be selected and/or matched.
Some devices or parts may not be commercially available in small quantities, or may be obsolete.
But I am building a tube amp. I am thinking about hand wire just like the high quality guitar amps. I don't know whether there are any particulars in layout of a hifi amp. But it it is about avoiding cross talk, noise etc. I do have experience in signal integrity, pcb layout and general electronic knowledge as I am an EE. But as I said, I am absolutely green in this field, so I don't dare to say I can do it. Just want some guidance here. Maybe you are right that after known the details, it might be better off buying a used one.
Thanks
Well, tube amps can be just as hard to copy, maybe more so if it's an older unit with parts that aren't available.
A used tube amp will often need extensive rebuilding though, but this is more straightforward than trying to copy it.
You might try an building an amp using Dynaco transformers, there are lots of used Dyna amps around, and even new transformers,
and also many DIY pcbs intended to work with these.
http://www.dynakitparts.com/index.php?route=common/home
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An old design will have compromises that are not necessary today in terms of cost effectiveness. Copying one verbatum is not wise if you are looking for fidelity. If nostalgia or some aesthetic values (no solid state devices etc.) are important in your project, then that is another thing entirely. It really depends on what your goals are.
OK, that's the really true reason for me looking into building the amp ( if it is feasible). If I go out and spend $2000 for a used amp, my big boss ( wife) is going to give me an instant review and it's not going to be diplomatic. But if I buy things $100 at a time like I do in my guitar amp, spreading out a little, so far she's ok on that!!!! I am sure those of you that have a big boss to answer to can sympathize with this!!!!
But this is really at a thinking stage, sounds like it's not as easy as guitar amp that we buy new parts and build.
. But if I buy things $100 at a time like I do in my guitar amp, spreading out a little, so far she's ok on that!!!! I am sure those of you that have a big boss to answer to can sympathize with this!!!!But this is really at a thinking stage, sounds like it's not as easy as guitar amp that we buy new parts and build.
Cary Amp Googled it, looking at some schematics right now.
I would start with collecting some basics. Like what amp do you want to emulate. Then start to collect the transformers. This is where the manufacturers save their $$ and get back their lost fidelity with time on the bench swapping wires & cheap components. You however may want to forgo that somewhat and simply purchase nice iron, which will make a huge difference in any design for the better. But you will have to know the schematic like the back of your hand, for instance the open circuit HV rating, available current for the power XMF, bandwidth of the finished power supply design. The input/output impedance of the output XMF as well. The Cary amp I just looked at has dual 5U4 rectifiers. Extra 5 volt load on the average power xmf. Don't forget, around here I believe the members are out to not only match a good design, but in many ways, exceed it in usability & versatility.
I for instance am exactly with you regarding my HiFi amp project. I've found "Franks Ultimate Pre-Amp". Which has sidelined my plans while I get comfortable with the whole separate Pre-Amp idea all together. I an also lucky to have my hands on a bunch of surplus 50 to 60- year old test equipment/tube chassis. So I'm transformer rich! Now what. Find an good ole design to copy. But around here there are so many who have perfected and upgraded the Dynaco & Heath Kit designs. I'll maybe go with the 6SN7 & EL34 or 6L6 since I have a bunch of these given to me from other amp building friends locally. Get w/ these folks in your area. Nothing like spending a few hours and a cup of coffee with someone who does not own a cure for a messy bench!
Doug
I would start with collecting some basics. Like what amp do you want to emulate. Then start to collect the transformers. This is where the manufacturers save their $$ and get back their lost fidelity with time on the bench swapping wires & cheap components. You however may want to forgo that somewhat and simply purchase nice iron, which will make a huge difference in any design for the better. But you will have to know the schematic like the back of your hand, for instance the open circuit HV rating, available current for the power XMF, bandwidth of the finished power supply design. The input/output impedance of the output XMF as well. The Cary amp I just looked at has dual 5U4 rectifiers. Extra 5 volt load on the average power xmf. Don't forget, around here I believe the members are out to not only match a good design, but in many ways, exceed it in usability & versatility.
I for instance am exactly with you regarding my HiFi amp project. I've found "Franks Ultimate Pre-Amp". Which has sidelined my plans while I get comfortable with the whole separate Pre-Amp idea all together. I an also lucky to have my hands on a bunch of surplus 50 to 60- year old test equipment/tube chassis. So I'm transformer rich! Now what. Find an good ole design to copy. But around here there are so many who have perfected and upgraded the Dynaco & Heath Kit designs. I'll maybe go with the 6SN7 & EL34 or 6L6 since I have a bunch of these given to me from other amp building friends locally. Get w/ these folks in your area. Nothing like spending a few hours and a cup of coffee with someone who does not own a cure for a messy bench!
Doug
Hi Doug
I named Cary because that's the only one I know is high quality. What other brands should I look at? Is Conrad Johnson at par with Cary? I am definitely looking for at least 40W per channel or more. Maybe 6CA7/EL34 or 6L6 type as I have tubes already.
Is the OT the most important component? In guitar amp, OT is not that expensive as we only work to about 5KHz. Hifi needs to go up to 20KHz.
Thanks
I named Cary because that's the only one I know is high quality. What other brands should I look at? Is Conrad Johnson at par with Cary? I am definitely looking for at least 40W per channel or more. Maybe 6CA7/EL34 or 6L6 type as I have tubes already.
Is the OT the most important component? In guitar amp, OT is not that expensive as we only work to about 5KHz. Hifi needs to go up to 20KHz.
Thanks
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Alan,
That 4 Ohm number you mentioned for the 913.1 is a distinct warning. What does the spec. sheet say is the minimum impedance? If the impedance curve dips down to 2 Ohms or so, off the shelf O/P "iron" will not do. Tube power amps don't have the large damping factors "sand" amps exhibit and 2 Ohm speaker taps require custom winding.
Frankly, you may be better off building a nice tubed line stage, with good drive capability, and mating it to a superior SS power amp. Also, you did not state what the budget is. You indicated what was too high.
BTW, experience with tubed guitar amps is of use in tubed HIFI amp construction. Some time ago, a member suggested that a tubed HIFI amp is a guitar amp gussied up in lipstick and nylons.
Finally, I suggest you stay away from Cary designs. IMO, they are seriously flawed. Just look at how Cary ABUSES vacuum rectifiers.
That 4 Ohm number you mentioned for the 913.1 is a distinct warning. What does the spec. sheet say is the minimum impedance? If the impedance curve dips down to 2 Ohms or so, off the shelf O/P "iron" will not do. Tube power amps don't have the large damping factors "sand" amps exhibit and 2 Ohm speaker taps require custom winding.
Frankly, you may be better off building a nice tubed line stage, with good drive capability, and mating it to a superior SS power amp. Also, you did not state what the budget is. You indicated what was too high.
BTW, experience with tubed guitar amps is of use in tubed HIFI amp construction. Some time ago, a member suggested that a tubed HIFI amp is a guitar amp gussied up in lipstick and nylons.
Finally, I suggest you stay away from Cary designs. IMO, they are seriously flawed. Just look at how Cary ABUSES vacuum rectifiers.
As far as building an amp, I'm on the DIY side of the fence. You have the background and the ability to build hifi amp. Deciding what to build may take a while, which seems to be ok with you.
The speakers you have seem to be bi-ampable. You may want to consider running the woofers with your SS amp, and building a lower powered tube amp for the mids & tweeters. Just throwing that out there.
jeff
GuyZ? I'm using this thread to learn as well..........
For me, I will still use my Sub Bass class D FET amp, but for 50Hz and above is my project. Yes! The OT is extensively designed for HiFi. For me & my EL34/6L6 needs, somewhere around 3 to 5Kohm.
Good Amp design ? What does the Cary have the other's don't? Slew rate? Bandwidth? Life style? Good looks, that it has.....
For me, I will still use my Sub Bass class D FET amp, but for 50Hz and above is my project. Yes! The OT is extensively designed for HiFi. For me & my EL34/6L6 needs, somewhere around 3 to 5Kohm.
Good Amp design ? What does the Cary have the other's don't? Slew rate? Bandwidth? Life style? Good looks, that it has.....
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