Being a total beginner in unaided DIY I find that having read hundreds of pages on these forums that VERY little information/opinion is offered regarding the sound quality of published designs.
As I want to build a power amp which sounds as near as possible sweet as opposed to sterile, fast, accurate and which will drive Impulse H2 horns (about95Db) I will be very grateful if a music (mainly classical) will point me in the right direction.
I play mainly LPs on a highly modded Technics SP10Mk11, a Zeta arm carries an original Audionote Io cartridge , a very simple amplification system which has to do as my prototype Be Yamamura amplifiers have broken down. Be seems to have dissappeared again. (ANDREW T - I now live in Kelso!!!)
I can solder, build circuits but I know NO theory that you would notice. Any suggestions / help very much appreciated re. choice of circuit.
Regards to all,
Brianco
As I want to build a power amp which sounds as near as possible sweet as opposed to sterile, fast, accurate and which will drive Impulse H2 horns (about95Db) I will be very grateful if a music (mainly classical) will point me in the right direction.
I play mainly LPs on a highly modded Technics SP10Mk11, a Zeta arm carries an original Audionote Io cartridge , a very simple amplification system which has to do as my prototype Be Yamamura amplifiers have broken down. Be seems to have dissappeared again. (ANDREW T - I now live in Kelso!!!)
I can solder, build circuits but I know NO theory that you would notice. Any suggestions / help very much appreciated re. choice of circuit.
Regards to all,
Brianco
Welcome to the forums!
Re sweet-sounding power amps for your horns, my vote would go to something like F2 from Pass Labs. Pass amps are as sweet as you can get with a sand amp. And if you really have a sweet ear, you may wish to consider a tube amp project like Shawn suggested. Whatever you choose, it should be a Class A amplifier. 10W or so should suffice, IMO.
If it's not too much of a bother, I'd appreciate it if you could write a line or two on those Technics mods you've made.
Regards,
Milan
Re sweet-sounding power amps for your horns, my vote would go to something like F2 from Pass Labs. Pass amps are as sweet as you can get with a sand amp. And if you really have a sweet ear, you may wish to consider a tube amp project like Shawn suggested. Whatever you choose, it should be a Class A amplifier. 10W or so should suffice, IMO.
If it's not too much of a bother, I'd appreciate it if you could write a line or two on those Technics mods you've made.
Regards,
Milan
Hi Brianco,
As Milan said, Welcome to the forums!
I will suggest a rather broader range of amplifiers. Many sound very good, and bad with each technology. So now it really comes down to what you are comfortable building, and how loud you like it. The only time I peak my amps are when I'm playing classical music, rock not nearly as often.
The Symasym is a really nice sounding 50 watt solid state "kit", and board layouts are available. You can also buy some kits proper, including PCB's and parts.
On the tube front, you may want to look at a P-P 6BQ5 setup (10 ~ 14 watts). Most sound really nice. I you wish more power, then I'd suggest an ultralinear 6L6GC or EL-34 / 6CA7 type. Those can get up to 50 watts and 450 VDC supplies. Yes, you can go further.
So, can you give us a clue as to what you are comfortable with and how loud you are likely to turn it up. Be honest because it's only yourself you would be fooling.
-Chris
As Milan said, Welcome to the forums!
I will suggest a rather broader range of amplifiers. Many sound very good, and bad with each technology. So now it really comes down to what you are comfortable building, and how loud you like it. The only time I peak my amps are when I'm playing classical music, rock not nearly as often.
The Symasym is a really nice sounding 50 watt solid state "kit", and board layouts are available. You can also buy some kits proper, including PCB's and parts.
On the tube front, you may want to look at a P-P 6BQ5 setup (10 ~ 14 watts). Most sound really nice. I you wish more power, then I'd suggest an ultralinear 6L6GC or EL-34 / 6CA7 type. Those can get up to 50 watts and 450 VDC supplies. Yes, you can go further.
So, can you give us a clue as to what you are comfortable with and how loud you are likely to turn it up. Be honest because it's only yourself you would be fooling.
-Chris
moamps said:
Thank you all for your welcome & advice.
Regarding the SP10, it is an ex-BBC TT, so has the big PS unit, in which there is some spare room. Virtually all electronics have been removed from the TT into the PS enclosure. They are joined by an umbilical cord. The deck is in an obsidian plinth (The Technics heavier one) from which the spongy supports have been replaced with large blocks of of pure fine structure carbon. Underneath is a Yamamura "sliding" equipment base. The Zeta is mounted on a carbon armboard, but it is soon to be replaced with a homemade dual-pivot ceramic and carbon 12" arm. The cartridge is the very earliest Audionote Io and has been rebuilt by Kondo about 4/5 years ago and is still working well. All wiring is with Be Yamamura early types & prototypes. It works well. I have a carbon 12"o/d disc (x1.25" deep) which I hope to have machined asa replacement platter.
Hope this gives you a clue. I have no Pics as all my cameras are film cameras.
Best wishes,
Brianco.
Hi AndrewT,
Heriot - if you were within 10 miles - is the ONLY place one COULD arrive, take any other direction one wouldbe leaving...! And I thought I had led a remote existance when I lived in rural Ireland.
Thanks for your note - hope we can meet up sometime. I have to behave myself for a while until some big man allows me to eMail anyone - when I am out of quarantine I will send you my tel. no.
Kindest regards,
Brianco
Heriot - if you were within 10 miles - is the ONLY place one COULD arrive, take any other direction one wouldbe leaving...! And I thought I had led a remote existance when I lived in rural Ireland.
Thanks for your note - hope we can meet up sometime. I have to behave myself for a while until some big man allows me to eMail anyone - when I am out of quarantine I will send you my tel. no.
Kindest regards,
Brianco
I am getting too old to solder tiny parts onto circuit boards, so I chose the modular approach ... and stripped down an existing (broken) amp to save a little on chasing around for all the parts ...
So, here is what I did: http://3dotaudio.com/ampics.html
Setup driving a pair of 86db planar speakers : http://www.magnepan.com/model_MMG
This setup sure sound good IMOP.
So, here is what I did: http://3dotaudio.com/ampics.html
Setup driving a pair of 86db planar speakers : http://www.magnepan.com/model_MMG
This setup sure sound good IMOP.
Hi Brianco
Someone recently asked about Bailey designs from the 1960's. One of his circuits I built could be good, as a starting point. This circuit appeared to receive little attention as a power amplifier. It was a "DC laboratory amplifier" published in Electronic Engineering.
Today, the specification may be a little pedestrian (typical distortion 0.01%) but it certainly has a good sound quality. In the published circuit, a differential input stage fed a single-VAS and a complementary driver/output pair. In other words, quite basic.
The key to the sound quality I think lies in the use of phase-lead compensation. This is where a feedback capacitor is taken from the VAS collector to the feedback point rather than the base of the VAS. This has the effect of reducing transient distortion rather than exacerbating it. John Linsley Hood used this approach, as I believe has Nelson Pass.
However, to get the best results I have found that a 220 pF compensation capacitor is about optimum as this also provides loading to avoid high frequency oscillation ( a subtle effect).
But to achieve a useful bandwidth of say 200 kHz the feedback resistor has to be in the order of 1.5k rather than the usual 10 k used in many diff-input circuits. This unbalances the differential pair if 10k is used on the input side. I have added a separate bias transistor to offset the DC bias so that this is no longer an issue. The solution is not elegant, but the sound quality is comparable to tube amps.
None of the original transistors I think are now available. The 40361/40362 devices could be replaced by BD139-BD140's and these in fact are very good devices, with typical gains on todays production devices (from ST and ON semi for exampe) are about 100, and in fact the lower spec. appears to have been increased from when these were first introduced.
The output devices were 2N3716/2N3792. I have built amps using 2N3055/MJ2955 pairs running happily from +/-35V power rails. The current production 2N3055/MJ2955 devices are epi and have fT's of around 5 MHz on those I have measured. Breakdown voltages have been over 80V, which I think may be due to the original RCA-2N3055 spec having BVcbo of 100V, which still has to be met.
Many people think that the 2N3055/MJ2955 are no longer the best, but they are on at least their 3rd major production revision, I think, and while the original 1 MHz RCA device was used in many amps, that really isn't hifi (as well as not being available anyway).
The biggest source of distortion seems to be from the gain non-linearity of the output devices, but even so 0.01% or thereabouts it quite respectable.
If you are interested, I will try to draw a circuit over the next few days.
Cheers
John
Someone recently asked about Bailey designs from the 1960's. One of his circuits I built could be good, as a starting point. This circuit appeared to receive little attention as a power amplifier. It was a "DC laboratory amplifier" published in Electronic Engineering.
Today, the specification may be a little pedestrian (typical distortion 0.01%) but it certainly has a good sound quality. In the published circuit, a differential input stage fed a single-VAS and a complementary driver/output pair. In other words, quite basic.
The key to the sound quality I think lies in the use of phase-lead compensation. This is where a feedback capacitor is taken from the VAS collector to the feedback point rather than the base of the VAS. This has the effect of reducing transient distortion rather than exacerbating it. John Linsley Hood used this approach, as I believe has Nelson Pass.
However, to get the best results I have found that a 220 pF compensation capacitor is about optimum as this also provides loading to avoid high frequency oscillation ( a subtle effect).
But to achieve a useful bandwidth of say 200 kHz the feedback resistor has to be in the order of 1.5k rather than the usual 10 k used in many diff-input circuits. This unbalances the differential pair if 10k is used on the input side. I have added a separate bias transistor to offset the DC bias so that this is no longer an issue. The solution is not elegant, but the sound quality is comparable to tube amps.
None of the original transistors I think are now available. The 40361/40362 devices could be replaced by BD139-BD140's and these in fact are very good devices, with typical gains on todays production devices (from ST and ON semi for exampe) are about 100, and in fact the lower spec. appears to have been increased from when these were first introduced.
The output devices were 2N3716/2N3792. I have built amps using 2N3055/MJ2955 pairs running happily from +/-35V power rails. The current production 2N3055/MJ2955 devices are epi and have fT's of around 5 MHz on those I have measured. Breakdown voltages have been over 80V, which I think may be due to the original RCA-2N3055 spec having BVcbo of 100V, which still has to be met.
Many people think that the 2N3055/MJ2955 are no longer the best, but they are on at least their 3rd major production revision, I think, and while the original 1 MHz RCA device was used in many amps, that really isn't hifi (as well as not being available anyway).
The biggest source of distortion seems to be from the gain non-linearity of the output devices, but even so 0.01% or thereabouts it quite respectable.
If you are interested, I will try to draw a circuit over the next few days.
Cheers
John
" as I believe has Nelson Pass."
Maybe he should consider the Pass A40. You can use either the darlingtons, or darlington connected drivers and outputs, and bias it any way you want (mount the Vbe on the heatsinks).
I have made some very high power versions of this (in class AB), the boards are still available for only $6 from AudioXpress.com
Maybe he should consider the Pass A40. You can use either the darlingtons, or darlington connected drivers and outputs, and bias it any way you want (mount the Vbe on the heatsinks).
I have made some very high power versions of this (in class AB), the boards are still available for only $6 from AudioXpress.com
Thank you all for your help. The Pass amp. would nterest me. I heard some of his amps in Italy a few years ago. They sounded very good indeed.
I have a pair of incomplete transformer in and out Class A amps - 2SK176 - in the garage. The first stage is missing as the transformers were used for something else. I cannot give the circuit as it is someone elses copyright. I have the full schematic in storage following a recent house move. In the meantime I want to get something better than the dreadful Oriental receiver into which I have attached a half decent pre amp. All the singers sound as if they are holding their noses throughout!!
Thank you all,
Brianco
I have a pair of incomplete transformer in and out Class A amps - 2SK176 - in the garage. The first stage is missing as the transformers were used for something else. I cannot give the circuit as it is someone elses copyright. I have the full schematic in storage following a recent house move. In the meantime I want to get something better than the dreadful Oriental receiver into which I have attached a half decent pre amp. All the singers sound as if they are holding their noses throughout!!
Thank you all,
Brianco
brianco: " Thank you all for your help. The Pass amp. would nterest me. I heard some of his amps in Italy a few years ago. They sounded very good indeed. ... "
It will be very hard to beat the quality of the Pass Labs' amps .... following the very thorough and details support, service and upgrade discussions right here at DIYAudio, you could hardly go wrong. ( Other support links & DIY sites related to Nelson Pass' amps: http://www.passlabs.com/links.htm )
It will be very hard to beat the quality of the Pass Labs' amps .... following the very thorough and details support, service and upgrade discussions right here at DIYAudio, you could hardly go wrong. ( Other support links & DIY sites related to Nelson Pass' amps: http://www.passlabs.com/links.htm )
Hi Brianco
Bailey's amp (1968) as I proposed to update and Nelson Pass's A40 (1978?) are almost identical so I think this confirms the performance.
I checked Bailey's distortion and its 0.01% is only at 1W. Simualtions show it rises to 0.04% at 40W, so class A is definitely better.
But if you use a pair of MJL3281A/MJL1302A the simulated distortion gets to be .01% at 40W, in class AB.
It'sup to you, but I'd go for the MJL output devices and run in Class AB unless you really want <.005% distortion - you may be able to run the MJL's in class A too...
Nordic
As I recall, the original TIP3055s made by TI have a BVceo of 70, but everyone else's is 60V. Most older transistors have to be derated for SOA down to about 200 mA at Vceo (60/70V) but the latest ON Semi 2N3055's have 40V at 115W rating and about 1A at 60V. So I think while your TIP's will probably be OK I'd recommend ON metal cans.
Cheers
John
Bailey's amp (1968) as I proposed to update and Nelson Pass's A40 (1978?) are almost identical so I think this confirms the performance.
I checked Bailey's distortion and its 0.01% is only at 1W. Simualtions show it rises to 0.04% at 40W, so class A is definitely better.
But if you use a pair of MJL3281A/MJL1302A the simulated distortion gets to be .01% at 40W, in class AB.
It'sup to you, but I'd go for the MJL output devices and run in Class AB unless you really want <.005% distortion - you may be able to run the MJL's in class A too...
Nordic
As I recall, the original TIP3055s made by TI have a BVceo of 70, but everyone else's is 60V. Most older transistors have to be derated for SOA down to about 200 mA at Vceo (60/70V) but the latest ON Semi 2N3055's have 40V at 115W rating and about 1A at 60V. So I think while your TIP's will probably be OK I'd recommend ON metal cans.
Cheers
John
john_ellis said:
Thank you Nordic, John, Fast Eddie and all,
I have had a look at the Pass DIY pages and find that Mr Pass has issued a circuit of his version of the JLH amp. It looks easy enough for a first attempt. Has anyone tested this design variation?
I have always believed - due to the opinion of others that the JLH sounds very similar to 1970s amps from a late JV ofSailsbury ...that is a sound I never want in my home again!! I had one for a few months and it was the only amp I have ever heard which literally gave me a headache after an hour or so. But clearly my info. on the JLH was based on dubious grounds.
Kind regards,
Brian
" ... Has anyone tested this design variation? ..."
Refering the gentleman to the answers of some moments ago: " ... Other support links & DIY sites related to Nelson Pass' amps: http://www.passlabs.com/links.htm ..."
"Truth is one, paths are many ..." The Dali Lama
Refering the gentleman to the answers of some moments ago: " ... Other support links & DIY sites related to Nelson Pass' amps: http://www.passlabs.com/links.htm ..."
"Truth is one, paths are many ..." The Dali Lama
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