What sort of PP amp? A pentode/UL/Williamson arrangement with 20dB+ of feedback, or a proper 300B PP DHT like the Amity? If the first, then I agre to an extent. If the latter, then I don't at all (I have one running as I type, ie DHT, but not 300B), as it has all the good bits of a set, but actually has the frequency extremes and considerably more immunity to loads and PSU.dhaen said:
Paul A. ,
Thank you. I read the pages you reffered to and the building instructions are very comprehensive. This is very important for me, just as using the 300B tube, so I'm almost convinced this is a suitable project for me.
The only remaining question is if the power will be enough for my proac response 2.5 diy. Their sensibility is 86 dB but they are a easy load as they don't go below 8ohm.
What kind of loudspekers do people use with the JE Labs 300? Have you heared that a low sensibility is OK if the impedance is not too low or that kind of similar information?
"...I'm sure you know that 10 watts is only 3dB less powerful than 20 watts...." If the difference is really this small, as dhean sais, I guess I don't have anything to worry about. My references are mostly differences between SS amps. But I know that tube power is much more "powerful" than SS power so I guess 9 W tube power can be quite a lot.
regards,
Per S
Thank you. I read the pages you reffered to and the building instructions are very comprehensive. This is very important for me, just as using the 300B tube, so I'm almost convinced this is a suitable project for me.
The only remaining question is if the power will be enough for my proac response 2.5 diy. Their sensibility is 86 dB but they are a easy load as they don't go below 8ohm.
What kind of loudspekers do people use with the JE Labs 300? Have you heared that a low sensibility is OK if the impedance is not too low or that kind of similar information?
"...I'm sure you know that 10 watts is only 3dB less powerful than 20 watts...." If the difference is really this small, as dhean sais, I guess I don't have anything to worry about. My references are mostly differences between SS amps. But I know that tube power is much more "powerful" than SS power so I guess 9 W tube power can be quite a lot.
regards,
Per S
Per, before you committ to building an amp that low in power, please either borrow one from someone and try it, or get an SPL meter, and see what sort of levels you actually have at your listening chair at the sort of levels you like.perka said:
A basic calculation:
ProAc = 86dB/1W/1m
8 watt amp = 9dBW ( dBW = 10 x log(amp power in W) )
subtotal = 95 dB SPL for 1 speaker
............. = 98 dB SPL for 2 speakers (approx,depends on room etc)
loss for 2.5m listening distance = 8dB
therefore peak SPL at the listening position is about 90dB (+/- a couple of dB) when the amp clips. At clipping, assuming that music has a peak/average ratio of around 20dB, your average level is a mere 70dB. IMO, this isn't enough power, unless your room is small, you sit close to the speakers and listen at low volumes to chamber music. Music always sounds more realistic when the system isn't clipping.
You might be happy with this situation, but before you shell out $$ on an experiment that may not work, find some way to measure the SPL at your chair, or try a similar amp.
One of the things amny people forget is the leading edge of the waveform is what we evolved listening to for survival, and lots of the information we take from any sound we hear is contained there. If your amp/speaker/room/listening position combo isn't able to produce these leading edges and peaks propely, music will sound compressed and lifeless, and your system no more than a glorifed Bose Waveradio. Of course your living arangements might dictate much lower levels but be sure, first. A 300B SE will not produce more than about 8W, and it's not like you have a "wattage" control on your amp, so after you build it, you just turn the knob and get 50W. It will undoubtedly require building a new amp.
Pro SPL calculator
http://www.doctorproaudio.com/doctor/calculadores_en.htm#calc_spl
Cheers
Brett, you do have point.
However I will not have the possibilty to borrow a 9W 300B and you are right, It's maybe then it's unwise not to be on the safe side and add some extra power - if your calculations are valid for the 300B. I know my proacs works very fine with 20W SE 300B, as I have listened to that. The sound level was even very strong.
dibblethwaite,
"...300B PSE Valve Monobloc Amplifier without valves - £875.00 (UK price) £745.00 (overseas price, exc. carriage)..."
If the price is for two monoblocks, I find it interesting. Also for me there is no duty from a european supplier.
Do you know something more about this amplifier. Do you know somebody who owns some of their amplifiers or the reputation of this firm?
Per S
However I will not have the possibilty to borrow a 9W 300B and you are right, It's maybe then it's unwise not to be on the safe side and add some extra power - if your calculations are valid for the 300B. I know my proacs works very fine with 20W SE 300B, as I have listened to that. The sound level was even very strong.
dibblethwaite,
"...300B PSE Valve Monobloc Amplifier without valves - £875.00 (UK price) £745.00 (overseas price, exc. carriage)..."
If the price is for two monoblocks, I find it interesting. Also for me there is no duty from a european supplier.
Do you know something more about this amplifier. Do you know somebody who owns some of their amplifiers or the reputation of this firm?
Per S
Yep. Trouble is, people get attached to the inefficient little squeezeboxes.Joel said:I would just ditch the 89dB speakers! Problem solved. Hell, then you can use any amp on the planet, and be happy.
I'm running around 106dB and have 20W. No such thing as dynamic compression here. Or noise, or distortion.
I think its more difficult to find a speaker that is close to your sound ideal than a amplifier that is close to the sound ideal and besides I have already heared them sound marvelous with a 20W so I won't follow your advice. And spending 5000usd for getting an efficient speaker (they start at that price if you don't build them yourself)? No.
Perka,
a) You can get a good speaker for MUCH less than $5,000! I know the snobs will jump all over me, but Cerwin Vega's aren't half bad speakers, and they are 102dB efficient, and around $200 each.
b) Your "ideal" can (and should) change over time, and with experience. Writing off a topology, or speaker style is self-limiting.
a) You can get a good speaker for MUCH less than $5,000! I know the snobs will jump all over me, but Cerwin Vega's aren't half bad speakers, and they are 102dB efficient, and around $200 each.
b) Your "ideal" can (and should) change over time, and with experience. Writing off a topology, or speaker style is self-limiting.
I'll gladly admit that Cerwin Vega are not bad for the money but is it fair to compare them to ProAc? A better amp and worse speaker may be a lateral move at best. I have had quite a few speakers (including CV 
) and find that efficiency is often accompanied by colourations. Severe ones too. The possibility exists in my mind that a reasonably neutral high efficiency speaker exists but i've never encountered one. Let me admit that my experience with horns involves only Lowthers and these inevitably give me a headache after a short while. Headache notwithstanding, they have other absolutely great qualities. As a comromise it doesn't work for me though it clearly works for others.
cheers
peter
) and find that efficiency is often accompanied by colourations. Severe ones too. The possibility exists in my mind that a reasonably neutral high efficiency speaker exists but i've never encountered one. Let me admit that my experience with horns involves only Lowthers and these inevitably give me a headache after a short while. Headache notwithstanding, they have other absolutely great qualities. As a comromise it doesn't work for me though it clearly works for others. cheers
peter
Jeez Peter, don't write off horns and other high eff speakers because of some (presumably) rear loaded Lowthers. Yuk. Probably the very worst of the type. A modern design front loaded horn is stunning and very low in colouration, and extremely low in distortion compared to almost any DR, at a realistic level, and has dynamics throughout the range DRs can only dream of.analog_sa said:
However, much as I dislike ProAcs (I owned some for years), buying a cheap pair of CVs is definitely a lateral move, at best. Some Tannoy Golds (or Reds if you're rich) or DMTs (100db/W) are a huge improvement in a decent box with a new crossover.
Perka,
I suggest you consider cutting a deal with Mozfet for his PSE output transformers, for sale in the Trading Post:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=9888
Cheers,
I suggest you consider cutting a deal with Mozfet for his PSE output transformers, for sale in the Trading Post:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=9888
Cheers,
After considering your doubts on my speaker efficiency, I better go for a more powerful design. I found that the Cary 805C must be close to what I'm looking for. I have done some searching but couldn't find any kits or drawings for this kind of design. Is this a very rare design?
" ....The CAD 805-C is a 50 Watt/channel Single-Ended Mono Block Amplifyer providing pure Class A triode power. The Tubes consist of a 6SL7 Input, a 300B Driver, a 845 Output, and a 1629 Power Indicator...."
Perka
" ....The CAD 805-C is a 50 Watt/channel Single-Ended Mono Block Amplifyer providing pure Class A triode power. The Tubes consist of a 6SL7 Input, a 300B Driver, a 845 Output, and a 1629 Power Indicator...."
Perka
Hi Perka,
try this link:
http://www.ainamoi.com/805c.htm
I have a number of observations:
Very high voltages are used with these valves. Knowledge of high voltage work practice is essential.
It is a commercial product, as such, AFAIK the transformer specification is not available.
It uses global negative feedback. The use of G-NFB in a transformer coupled design is critically dependant on transformer specification.
What kind of watts? Even with the NFB, I do not believe it can output more than 30w, bearing in mind the supply voltage and cathode bias arrangement.
However, IMO the basic topology is good.
Of course I would say that, because It's very similar to my own OnRyoku design:
http://www.dhaen.org.uk/vdocs/onryoku.htm
You are welcome to take ideas from it if you want
I am adding information all the time....
Cheers,
try this link:
http://www.ainamoi.com/805c.htm
I have a number of observations:
Very high voltages are used with these valves. Knowledge of high voltage work practice is essential.
It is a commercial product, as such, AFAIK the transformer specification is not available.
It uses global negative feedback. The use of G-NFB in a transformer coupled design is critically dependant on transformer specification.
What kind of watts? Even with the NFB, I do not believe it can output more than 30w, bearing in mind the supply voltage and cathode bias arrangement.
However, IMO the basic topology is good.
Of course I would say that,
because It's very similar to my own OnRyoku design:http://www.dhaen.org.uk/vdocs/onryoku.htm
You are welcome to take ideas from it if you want
I am adding information all the time....
Cheers,
John,
Your 845 seems to be perfect for my needs!
As I understand it you are still evaluating the design and I'm waiting to see the final outcome.
I have a lot of soldering experience, but none in tube amplifiers, so the high voltage is scaring me a bit. I have done a lot of reading about this since two days, and it seems that even a lot of experienced builders got electric chocks of 700V. I understand it that un unexpected source of electric chocks is often remaining current in the capacitors even a long time after the power is cut.
Actually, because of this I also need a very easy to understand schematic and a step to step guide where to measure the different voltages and check that they are OK before I put in the tubes.
So one way to go could be to build a amplifier with less dangerous voltage just for the experience and fun and then proceed with your project.
What do you think about building the "300B PSE MK2 - Parallel Single Ended" by Andrea Ciuffoli. I know yoy refer to his 845 project at your homepage, so I guess you have confidence in his projects.
http://www.audiodesignguide.com/my/pse2.html
Even if I won't be able to enjoy high music volymes with my proacs, I guess this amplifier would be very good with certain kind of music like cello and female voices.
This project also have the advantage that I don't need a
preamplifier for the use with my cd player.
My second question is about the recommended Lundahl transfomers in "300B PSE MK2 - Parallel Single Ended". They seem to cost about 700usd. Is this very high quality transformers? Could I buy some cheaper ones at still good quality and in such case where do I find them? The reson I ask is that the total cost in this project seems to exceed the 1000pound for a finished kit like the one at worldaudiodesign.
Per
Your 845 seems to be perfect for my needs!
As I understand it you are still evaluating the design and I'm waiting to see the final outcome.
I have a lot of soldering experience, but none in tube amplifiers, so the high voltage is scaring me a bit. I have done a lot of reading about this since two days, and it seems that even a lot of experienced builders got electric chocks of 700V. I understand it that un unexpected source of electric chocks is often remaining current in the capacitors even a long time after the power is cut.
Actually, because of this I also need a very easy to understand schematic and a step to step guide where to measure the different voltages and check that they are OK before I put in the tubes.
So one way to go could be to build a amplifier with less dangerous voltage just for the experience and fun and then proceed with your project.
What do you think about building the "300B PSE MK2 - Parallel Single Ended" by Andrea Ciuffoli. I know yoy refer to his 845 project at your homepage, so I guess you have confidence in his projects.
http://www.audiodesignguide.com/my/pse2.html
Even if I won't be able to enjoy high music volymes with my proacs, I guess this amplifier would be very good with certain kind of music like cello and female voices.
This project also have the advantage that I don't need a
preamplifier for the use with my cd player.
My second question is about the recommended Lundahl transfomers in "300B PSE MK2 - Parallel Single Ended". They seem to cost about 700usd. Is this very high quality transformers? Could I buy some cheaper ones at still good quality and in such case where do I find them? The reson I ask is that the total cost in this project seems to exceed the 1000pound for a finished kit like the one at worldaudiodesign.
Per
Hi Perka,
Yes, I am fully satisfied with my 845SE amp, even though I'm still making refinements.
You are correct about the high voltages stored in the capacitors. The high voltages also cause extra problems with insulation compared with sub-600 volt equipment.
The "300B PSE MK2 - Parallel Single Ended" by Andrea Ciuffoli, looks interesting. I haven't studied it in any detail yet. I'm reasonably confident that the knows what he's doing - though all his "projects" seem to use large quantit'es of Lundahl transformers and chokes. I think he must be the local dealer
He certainly does give detailed construction information, though I've not used it.
One important thing to check, is the input sensitivity. You may need a preamplifier for some sources.
The Lunahl transformers are regarded as good quality. If you use other transformers, you must be careful about the choice.
Did you check on the link I gave you?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=9888
This member is selling some output transformers made by "Audionote" that might be suitable. You should ask him the power rating and the primary impedance, if you are interested.
Cheers,
Yes, I am fully satisfied with my 845SE amp, even though I'm still making refinements.
You are correct about the high voltages stored in the capacitors. The high voltages also cause extra problems with insulation compared with sub-600 volt equipment.
The "300B PSE MK2 - Parallel Single Ended" by Andrea Ciuffoli, looks interesting. I haven't studied it in any detail yet. I'm reasonably confident that the knows what he's doing - though all his "projects" seem to use large quantit'es of Lundahl transformers and chokes. I think he must be the local dealer
He certainly does give detailed construction information, though I've not used it.
One important thing to check, is the input sensitivity. You may need a preamplifier for some sources.
The Lunahl transformers are regarded as good quality. If you use other transformers, you must be careful about the choice.
Did you check on the link I gave you?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=9888
This member is selling some output transformers made by "Audionote" that might be suitable. You should ask him the power rating and the primary impedance, if you are interested.
Cheers,
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