So I really want to buy and build a K-12G tube amp from tubedepot.com
Stereo Tube Amplifier Kit
Seems totally fine, great reviews and relatively easy to build unless you make some modifications which I probably will not do. However, in a review I read from audioXpress.com
http://diyaudioprojects.com/Tubes/K-12M/audioXpress-review-of-S5-Electronics-K-12M-Tube-Amp-Kit.pdf
the reviewer claims that the output is slightly lower than 8 W/channel which is fine, but...he also says he tested the kit on speakers which are rated for much higher RMS than that! Also, in another forum I read that one person put the speakers to Infinity P162's which are rated at 150W RMS. I know that it is possible to under power a speaker and trying to bump the levels up would eventually result in clipping because there isn't enough power to move the driver rated for that high of an input, but the author of that post claims to be getting wonderful sound at high enough levels. I am a little newb and this question is driving me crazy! Any answers?
Stereo Tube Amplifier Kit
Seems totally fine, great reviews and relatively easy to build unless you make some modifications which I probably will not do. However, in a review I read from audioXpress.com
http://diyaudioprojects.com/Tubes/K-12M/audioXpress-review-of-S5-Electronics-K-12M-Tube-Amp-Kit.pdf
the reviewer claims that the output is slightly lower than 8 W/channel which is fine, but...he also says he tested the kit on speakers which are rated for much higher RMS than that! Also, in another forum I read that one person put the speakers to Infinity P162's which are rated at 150W RMS. I know that it is possible to under power a speaker and trying to bump the levels up would eventually result in clipping because there isn't enough power to move the driver rated for that high of an input, but the author of that post claims to be getting wonderful sound at high enough levels. I am a little newb and this question is driving me crazy! Any answers?
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You have to use a high efficiency woofer (or a full-range speaker) with a 8W/channel amplifier, the more "dB per watt" (dB/W) is the best, ideally over 92dB/W (92 decibels at 1 watt RMS and 1 meter distance) no matter what maximum power it can handle. All speakers with the same SPL (sound pressure level) will play as loud with the same power, big or small.
Woofer like that habitually have a rigid suspension and not a soft one for "air suspension", but you need a much bigger enclosure which can be a "bass-reflex". For a 8 watts amplifier, you should use a speaker that can handle at least twice this power, a 15 watts model or more will be OK !
Some musical instrument speakers have a SPL over 105dB/W, they play very loud even at just one watt of power ... The sound pressure raise about 3dB each time the power double, so if you have a 92 dB/W speaker, at a power of 8 watts, the SPL will be about 101 dB, it is loud an off to disturb the neighbours ...
I plan to use a high efficiency woofer. I plan to use the Infinity 162's as I said earlier.
Infinity - Home Audio
I understand the concept in terms of loudness, but explain to me why I would use a speaker rated that high when I see all the time in books and forums that you should have at least 1.5*RMS for the speaker in amp power to have enough headroom to avoid clipping?
Infinity - Home Audio
I understand the concept in terms of loudness, but explain to me why I would use a speaker rated that high when I see all the time in books and forums that you should have at least 1.5*RMS for the speaker in amp power to have enough headroom to avoid clipping?
No.
Infinity Primus P162 Main / Stereo Speaker - Product details and features - DealTime
This speaker is pre built and 90dB 2.83 V/1 M. The RMS power handling is 150 W. How can that work with an 8 W/channel amp as I have been told to match the RMS power of the amp with the RMS power handling rating of the speaker?
Infinity Primus P162 Main / Stereo Speaker - Product details and features - DealTime
This speaker is pre built and 90dB 2.83 V/1 M. The RMS power handling is 150 W. How can that work with an 8 W/channel amp as I have been told to match the RMS power of the amp with the RMS power handling rating of the speaker?
don't worry about the RMS power handling. You need EFFICIENT and as flat an impedance curve as you can get. 90db is not terribly efficient - not bad, just not great. You can bet it was measured at the absolutely most advantageous point in the speakers efficiency profile, so expect a true efficiency less than this - perhaps 88db...
Is there any impedance curve data?
Is there any impedance curve data?
SoundStage! Measurements - Infinity Primus P162 Loudspeakers (11/2008)
They don't appear to be 90 db but more around 88 db. Do you have any suggestions for a better set of speakers under $400?
Also I still don't understand how you can not worry about RMS power handling. I know loudness is due in some part to efficiency, but I still fail to see how underpowering the speaker is not an issue at all, especially given that some have lower bounds for power on the data sheet?
Unless of course the theory is that the speakers can produce enough sound if they are high efficiency that regardless of RMS power handling capabilities you won't need to set the volume so high that you send the amp into clipping?
They don't appear to be 90 db but more around 88 db. Do you have any suggestions for a better set of speakers under $400?
Also I still don't understand how you can not worry about RMS power handling. I know loudness is due in some part to efficiency, but I still fail to see how underpowering the speaker is not an issue at all, especially given that some have lower bounds for power on the data sheet?
Unless of course the theory is that the speakers can produce enough sound if they are high efficiency that regardless of RMS power handling capabilities you won't need to set the volume so high that you send the amp into clipping?
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Hi milsman2,
You say you want to buy the K12G amp which uses 10GV8 tubes and run quite hard IIRC.
The review is of the K12M, a very similar amp by the same designer but uses the 11MS8 tubes.
Using different tubes can make an amp with an almost identical topology sound quite different so it may not be a good idea to judge the K12G from a review of the K12M.
Another version of this amp to consider is the K502, again almost identical except it uses the 11BM8 tube. This is an 11v heater version of the 6BM8 tube ( also known as the ECL82 ) and many manufacturers used it to good effect in their lower powered amps.
Brgds Bill
You say you want to buy the K12G amp which uses 10GV8 tubes and run quite hard IIRC.
The review is of the K12M, a very similar amp by the same designer but uses the 11MS8 tubes.
Using different tubes can make an amp with an almost identical topology sound quite different so it may not be a good idea to judge the K12G from a review of the K12M.
Another version of this amp to consider is the K502, again almost identical except it uses the 11BM8 tube. This is an 11v heater version of the 6BM8 tube ( also known as the ECL82 ) and many manufacturers used it to good effect in their lower powered amps.
Brgds Bill
They are a little pricey, but would work great with any low powered amp.
Audiophile Tube Amps and Tube Gear from DECWARE
Audiophile Tube Amps and Tube Gear from DECWARE
I'm nowheres near as knowledgeable as most here but, I do know there is no substitute for ample amp "power" as transients can eat up mucho watts in a instant and cause momentary clipping if there are not enought reserve watts.
It not just about overall volume
BTW, this reminds me of... ....why is there little mention of the "dynamic range" of any audio component anymore?
Is it now called something else?
It not just about overall volume
BTW, this reminds me of... ....why is there little mention of the "dynamic range" of any audio component anymore?
Is it now called something else?
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So they tell me but from what I have read the 8 W actually provides a decent amount of headroom for the transients.
The thing that you need to keep in mind is that sound pressure levels are measured on a logarithmic scale. This means that a 10W amp only peaks at 10dB higher than a 1W amp. A 150W amp only peaks at 17dB higher than a 10W amp or 27dB higher than a 1W amp.
So lets do a quick little thought experiment. Suppose that you have a 10W amp and a set of speakers with a 92dB efficiency rating. At 1W nominal output (about 1/2 volume) your speakers will produce a SPL of about 92dB at 1 meter (per channel). Both channels together will produce about 95dB. This is pretty good and music peaks that are up to 10dB higher will cleanly produce another 10dB or 105dB total SPL. But now lets up that amplifier to 100W. With the amplifier at half volume (about 10W) it will also produce 105dB. But musical peaks that are 10dB higher now produce 115dB SPL. This is close to the pain threshold. But at 1/4 volume (about 1 W) it will produce the same SPLs as your 10W amp at half volume but will be able to handle musical peaks that are 20dB instead of 10 dB without clipping. So what you've really bought with all that power is more headroom for volume excursions.
Here's a simple table assuming a stereo amplifier and a speaker efficiency of 90dB.
Code:
Amp Power per channel SPL (dB)
1 W 93dB
5 W 100dB
10 W 103dB
50 W 110dB
100W 113dB
200W 116dB
400W 119dB
So clearly there is a point of diminished returns where big power amp really doesn't buy you that much more volume.
Does this make sense?
The thing that you need to keep in mind is that sound pressure levels are measured on a logarithmic scale. This means that a 10W amp only peaks at 10dB higher than a 1W amp. A 150W amp only peaks at 17dB higher than a 10W amp or 27dB higher than a 1W amp.
So lets do a quick little thought experiment. Suppose that you have a 10W amp and a set of speakers with a 92dB efficiency rating. At 1W nominal output (about 1/2 volume) your speakers will produce a SPL of about 92dB at 1 meter (per channel). Both channels together will produce about 95dB. This is pretty good and music peaks that are up to 10dB higher will cleanly produce another 10dB or 105dB total SPL. But now lets up that amplifier to 100W. With the amplifier at half volume (about 10W) it will also produce 105dB. But musical peaks that are 10dB higher now produce 115dB SPL. This is close to the pain threshold. But at 1/4 volume (about 1 W) it will produce the same SPLs as your 10W amp at half volume but will be able to handle musical peaks that are 20dB instead of 10 dB without clipping. So what you've really bought with all that power is more headroom for volume excursions.
Here's a simple table assuming a stereo amplifier and a speaker efficiency of 90dB.
Code:
Amp Power per channel SPL (dB)
1 W 93dB
5 W 100dB
10 W 103dB
50 W 110dB
100W 113dB
200W 116dB
400W 119dB
So clearly there is a point of diminished returns where big power amp really doesn't buy you that much more volume.
Does this make sense?
Room size and music choices matter too. I have been playing with a 4" full range system having efficiency of no more than about 88dB-W-m using SE KT-88s (8 or 10wpc I would guess) and it can get quite loud in my 12x12 listening area. It does have limitations though.
It is going to be hard to find affordable bookshelf speakers with much better sensitivity than 90dB so unless someone comes up with something I wouldn't stress too much about getting an extra dB or two. You can get more efficiency but physics comes into play at some point in that you can have small, efficient, deep bass but only two at a time.
One advantage you have over most SS amps is that the overload should be comparably graceful. It will compress quite a bit before you get hard clipping which means that even though you may miss some of the dynamics that a more efficient speaker would give you it shouldn't sound like &^&*#%^& every time they whack the bass drum.
Worst case is that you will eventually get the itch to build another amp or a set of speakers. Its all good.
It is going to be hard to find affordable bookshelf speakers with much better sensitivity than 90dB so unless someone comes up with something I wouldn't stress too much about getting an extra dB or two. You can get more efficiency but physics comes into play at some point in that you can have small, efficient, deep bass but only two at a time.
One advantage you have over most SS amps is that the overload should be comparably graceful. It will compress quite a bit before you get hard clipping which means that even though you may miss some of the dynamics that a more efficient speaker would give you it shouldn't sound like &^&*#%^& every time they whack the bass drum.
Worst case is that you will eventually get the itch to build another amp or a set of speakers. Its all good.
looks like your budgeting $400 for amp too? Take a look at the tubelab.com Simple PP EL84 amp and on this form under the commercial section. Gives 15W/CH in PP with tubes that are presently manufactured. Useful with more speakers. More power will be a bonus plus lots of help on the form. Though it's not mentioned on Georges's website as it needs work, he may have still available parts kits for an extra $65 on top of the the board price of $35. Sonics on all his amps are well liked. The Simple SE and PP ones would be easy builds too and you could do it for $400 with decent output transformers. JJ EL84 output tubes are nice sounding and affordable @$10 ea.
http://www.tubelab.com/
http://www.diyaudio.com/forums/tubelab/148694-tubelab-simple-p-p.html
The output transformers are kind of small on the amp you mentioned to keep the price down and that really determines a lot of the sonics, plus the tubes used may be hard to find down the road as they are no longer manufactured.
http://www.tubelab.com/
http://www.diyaudio.com/forums/tubelab/148694-tubelab-simple-p-p.html
The output transformers are kind of small on the amp you mentioned to keep the price down and that really determines a lot of the sonics, plus the tubes used may be hard to find down the road as they are no longer manufactured.
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Well ... here's one more opinion.
I am not a fan of diverting a thread from "I want to build this" to "You should build that".
Here's my experience.
In my bedroom, I have a Squeezebox Classic which drives a Bottlehead Foreplay (version 1) preamp (a buffer would be better) into a pair of Bottlehead Paramour (version 1) amps into a pair of ADS L1090 speakers (efficiency 89db).
Mostly I listen to what most would call "Folk Music" with the occasional Baroque or Aaron Copland diversion.
I am 59 years old - that system is the best I have ever owned.
The room is not huge - my king size bed takes up way too much of it.
If it was my money for your project - I would listen to rmyauck and visit the TubeLab section.
When the EL84's run out of gas they will still sound gorgeous.
Just my opinion - not humble, just somewhat experienced.
I am not a fan of diverting a thread from "I want to build this" to "You should build that".
Here's my experience.
In my bedroom, I have a Squeezebox Classic which drives a Bottlehead Foreplay (version 1) preamp (a buffer would be better) into a pair of Bottlehead Paramour (version 1) amps into a pair of ADS L1090 speakers (efficiency 89db).
Mostly I listen to what most would call "Folk Music" with the occasional Baroque or Aaron Copland diversion.
I am 59 years old - that system is the best I have ever owned.
The room is not huge - my king size bed takes up way too much of it.
If it was my money for your project - I would listen to rmyauck and visit the TubeLab section.
When the EL84's run out of gas they will still sound gorgeous.
Just my opinion - not humble, just somewhat experienced.
The bookshelf 90dB/W Infinity Primus P162 you was talking about is not enought sensitive for a 8 W RMS/channel amplifier. It's made for a power range of 10 to 150 watts ...
You should consider using a low power and high efficiency speaker like the Audio Nirvana Series ... They sale very good "full-range" loudspeakers alone and also bookshelf cabinet for them and if you like to build the cabinet yourself, they have the plan free when you buy them ... You can also see all the "Thiele and Small" parameters on their WEB site and calculate the perfect size of the cabinet with a free design software like Basta, it is very good and easy to use.
See what they say about the Super 6.5 for example (138$/pair + shipping) :
Audio Nirvana said:
The parameters and response curve of the Super 6.5
Look at their CommonSense Audio distributor WEB site, it is very complete and interesting. There must be some members of this forum who already know about those loudspeakers. They are perfect for a 8 watts/channel tubes amplifier and their price are affordable.
Cheers.
Alain.
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Unfortunately I really just want to get the ball rolling on this project. Also I really don't want to spend time currently in any building of speakers. I will most likely use these
http://www.amazon.com/gp/product/B00006JPDI/ref=nosim/102-0630389-9128166?n=172282
and based on the replies I've gotten so far I will still be fine. However, that being said, what does everyone think about the K-502 instead?
Tubelab Home
http://www.amazon.com/gp/product/B00006JPDI/ref=nosim/102-0630389-9128166?n=172282
and based on the replies I've gotten so far I will still be fine. However, that being said, what does everyone think about the K-502 instead?
Tubelab Home
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An alternative is a plan I call "just do it". I'm a little disappointed my plan name was misappropriated by a multinational sportswear company, but hey...
The Just do it plan is based on an old motorcycle racing ethos - "run what ya brung", or in other words use what you've got.
In your case, it means get the speakers that you think will suit - and lets face it even your first choice will do an ok job. Then get the amp you planned to build, put it together and play.
Because I can ensure you of one thing - once you've built one, more will follow. As will other speakers. So your start point is just that - a start point.
Begin.
The Just do it plan is based on an old motorcycle racing ethos - "run what ya brung", or in other words use what you've got.
In your case, it means get the speakers that you think will suit - and lets face it even your first choice will do an ok job. Then get the amp you planned to build, put it together and play.
Because I can ensure you of one thing - once you've built one, more will follow. As will other speakers. So your start point is just that - a start point.
Begin.
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