Its about as generic as there is, there are only so many ways to hook up these parts and still have them work.
DH 200
Hey:
Check out www.musicalconcepts.com for info on their mods. Makes a great sounding amp with their new boards and dual mono power supply conversions.
Hope this helps
Ed
Hey:
Check out www.musicalconcepts.com for info on their mods. Makes a great sounding amp with their new boards and dual mono power supply conversions.
Hope this helps
Ed
Re: DH 200
I looked into the musicalconcepts boards. By the time you buy all of the stuff you will have over $400 invested plust the original price you paid for the amp. When you say great sounding amp, just how great does it sound? Anything in the realm of Aleph or ESP?
Thanks, Terry
eds65gto said:
I looked into the musicalconcepts boards. By the time you buy all of the stuff you will have over $400 invested plust the original price you paid for the amp. When you say great sounding amp, just how great does it sound? Anything in the realm of Aleph or ESP?
Thanks, Terry
I live within 30 miles of Musical Concepts, and asked if I could bring in my unmodded DH-200 or my unmodded DH-500, and compare with some of his modded gear. He didn't sound too enthused about it... exchange was as follows...
me: Any chance of "A/Bing" between one of my amps and a modded one?
him: Not to act abrasive, but would you waste your time comparing a Chevy Malibu to a Ferrari?
That makes me nervous... Has anyone else done any comparisons? I mean, I should just fork over the $$$, and be happy?
me: Any chance of "A/Bing" between one of my amps and a modded one?
him: Not to act abrasive, but would you waste your time comparing a Chevy Malibu to a Ferrari?
That makes me nervous... Has anyone else done any comparisons? I mean, I should just fork over the $$$, and be happy?
Bogie:
How much money do you want to spend on an experiment?
That's what it boils down to.
I'd want to see how the basic Halfer design could be improved
through circuit upgrades or even new driver boards entirely.
Reworking an old amplifier with new parts may fix tired parts
and will probably improve the sound somewhat--especially if
there are genuinely bad parts--but I keep going back to the
basic design.
There are some good suggestions so far, but it's up to you how
to spend the money.
I would NOT spend several hundred dollars replacing the power
supply caps with Black Gates, however. Put the premium parts
in the input and feedback stages. On general principle I would
'shotgun' the whole amplifier with new metal film resistors and
good quality electrolytic caps, replace the input connectors with
gold-plated parts, and maybe replace the output transistors.
Pay particular attention to solder joints; my old projects still
sometimes embarrass me with cold solder joints.
How much money do you want to spend on an experiment?
That's what it boils down to.
I'd want to see how the basic Halfer design could be improved
through circuit upgrades or even new driver boards entirely.
Reworking an old amplifier with new parts may fix tired parts
and will probably improve the sound somewhat--especially if
there are genuinely bad parts--but I keep going back to the
basic design.
There are some good suggestions so far, but it's up to you how
to spend the money.
I would NOT spend several hundred dollars replacing the power
supply caps with Black Gates, however. Put the premium parts
in the input and feedback stages. On general principle I would
'shotgun' the whole amplifier with new metal film resistors and
good quality electrolytic caps, replace the input connectors with
gold-plated parts, and maybe replace the output transistors.
Pay particular attention to solder joints; my old projects still
sometimes embarrass me with cold solder joints.
A40 pcb into hafler dh-xxx
your experiance with musical concepts doesnt surprize me
their mod is awfully pricey!
still think the pass a 40 pcb maybe the best (and cheapest )way
I plan to try it sometime after christmas when i have more time
if anyone is interested i will post a schematic.
your experiance with musical concepts doesnt surprize me
their mod is awfully pricey!
still think the pass a 40 pcb maybe the best (and cheapest )way
I plan to try it sometime after christmas when i have more time
if anyone is interested i will post a schematic.
MC Mods
Still4Given,
"I looked into the musicalconcepts boards. By the time you buy all of the stuff you will have over $400 invested plus the original price you paid for the amp. When you say great sounding amp, just how great does it sound? Anything in the realm of Aleph or ESP?"
I have both a DH-200 amp and an MC modified amp with the PA-3B boards. The sound of an amp is mostly in the circuit card and, to a degree, in the power supply. The output MOSFETs produce whatever sound is given to them.
The MC PA-3B boards make for an amp with much smoother and more detailed and more "natural" sound than the stock DH-200 or DH-220 or P-225 or P-230 amps. I know which I prefer and the Hafler amps with their original circuit cards come out on the losing end. Many others claim that the PA-3B cards in an old Hafler chassis performs like a $1,000 amp. This assumes that you also include the updated PS caps.
As with any of these mods the difference is not always a "wow." Much depends on the goodness of the rest of the system, how a person listens, what a person listens for, and what a person listens to.
Still4Given,
"I looked into the musicalconcepts boards. By the time you buy all of the stuff you will have over $400 invested plus the original price you paid for the amp. When you say great sounding amp, just how great does it sound? Anything in the realm of Aleph or ESP?"
I have both a DH-200 amp and an MC modified amp with the PA-3B boards. The sound of an amp is mostly in the circuit card and, to a degree, in the power supply. The output MOSFETs produce whatever sound is given to them.
The MC PA-3B boards make for an amp with much smoother and more detailed and more "natural" sound than the stock DH-200 or DH-220 or P-225 or P-230 amps. I know which I prefer and the Hafler amps with their original circuit cards come out on the losing end. Many others claim that the PA-3B cards in an old Hafler chassis performs like a $1,000 amp. This assumes that you also include the updated PS caps.
As with any of these mods the difference is not always a "wow." Much depends on the goodness of the rest of the system, how a person listens, what a person listens for, and what a person listens to.
Hi Dick,
Thanks for the reply. I hope I didn't come off negative in my post. I am honestly interested in just how big a difference the MC stuff makes. Do you think the MC boards and PSU upgrade bring the amp up to the sound quality of an Aleph?
I own the DH200, and a couple of P230's. They sound pretty much the same to me. The P230's are a little louder but that is about all the difference I hear. My Soundcraftsmen amps sound much better to my ears.
For $400 I can almost build an Aleph. If the MC stuff won't get me there, I'd be better off selling the Haflers and building something. What do you think?
Thanks, Terry
Thanks for the reply. I hope I didn't come off negative in my post. I am honestly interested in just how big a difference the MC stuff makes. Do you think the MC boards and PSU upgrade bring the amp up to the sound quality of an Aleph?
I own the DH200, and a couple of P230's. They sound pretty much the same to me. The P230's are a little louder but that is about all the difference I hear. My Soundcraftsmen amps sound much better to my ears.
For $400 I can almost build an Aleph. If the MC stuff won't get me there, I'd be better off selling the Haflers and building something. What do you think?
Thanks, Terry
I have never heard an Aleph so there is no way I can make a comparison.
All I can tell you is that the MC PA-3B is the best amp I have ever used in my home and others share my belief. Go to the Madisound message board and pose a question as I know at least two of the guys who hang there use MC products and swear by them. Ditto for the PartsExpress message board.
Check out reviews on the Aleph. There were some that said it had a "loose" almost "flabbby" bass. It shines in the midrange, much like a tube amp, but is lacking in the top and bottom of its range -- much like many tube amps do.
You have to sort out the over enthusiastic comments in the Aleph thread. No amp sounds as good as the one you build. Right? Read reviews on the Aleph at locations different from this web site. It was listed as a Product of the Year by Stereophile about 10 years ago. Perhaps you can still find this review in Stereophile's archives. Check AudioReview for comments. Go to AudioAsylum and dig around for some reviews or comments about the sound of the Aleph.
I don't know what you cherish in the way of sound. Some of your comments about watts and volume make me wonder if loudness is a main ingredient. On the other hand you mentioned Brubeck, Desmond and Mulligan, which helps me to believe you would really like the sound of the MC PA-3B.
Will you use this amp in your Home Theater or strictly for stereo listening? If in the HT room you will want 2-3 other amps just like it as all amps in an HT setting should be of similar topology. Amps do have a little phase shift, just as do speaker systems. For example, I found that a Hafler and an MC amp do not blend well in an HT 5.1 system.
Another consideration is the type of speaker you will use. The Aleph has a very poor damping factor for the bass, just as do many tube amps.
Well, that's about all the speculation I can make without sounding silly.
Good luck. Let us know what you do.
Dick
All I can tell you is that the MC PA-3B is the best amp I have ever used in my home and others share my belief. Go to the Madisound message board and pose a question as I know at least two of the guys who hang there use MC products and swear by them. Ditto for the PartsExpress message board.
Check out reviews on the Aleph. There were some that said it had a "loose" almost "flabbby" bass. It shines in the midrange, much like a tube amp, but is lacking in the top and bottom of its range -- much like many tube amps do.
You have to sort out the over enthusiastic comments in the Aleph thread. No amp sounds as good as the one you build. Right? Read reviews on the Aleph at locations different from this web site. It was listed as a Product of the Year by Stereophile about 10 years ago. Perhaps you can still find this review in Stereophile's archives. Check AudioReview for comments. Go to AudioAsylum and dig around for some reviews or comments about the sound of the Aleph.
I don't know what you cherish in the way of sound. Some of your comments about watts and volume make me wonder if loudness is a main ingredient. On the other hand you mentioned Brubeck, Desmond and Mulligan, which helps me to believe you would really like the sound of the MC PA-3B.
Will you use this amp in your Home Theater or strictly for stereo listening? If in the HT room you will want 2-3 other amps just like it as all amps in an HT setting should be of similar topology. Amps do have a little phase shift, just as do speaker systems. For example, I found that a Hafler and an MC amp do not blend well in an HT 5.1 system.
Another consideration is the type of speaker you will use. The Aleph has a very poor damping factor for the bass, just as do many tube amps.
Well, that's about all the speculation I can make without sounding silly.
Good luck. Let us know what you do.
Dick
Thanks Dick,
I have never heard an Aleph either. I just keep hearing good things about them.
The reason I have talked about watts and power is because most of the systems that have really sounded pleasing to me, always had a lot of headroom. It seems like the lower powered stuff lost something in the separation. I haven't heard a lot of stereophile type systems though.
I'm not sure what I would be using the MC modded Hafler for right now. If the audio quality is quite improved, I would probably use it in my studio to drive my nearfield monitors. Right now my Haflers are just sitting because my Soundcraftsmen amps just sound better. I've assumed that is because of the added headroom, but I could be wrong about that.
The main speakers I drive right now are some JBL 4425's and 4412's. My nearfields are Event 20/20's.
Right now I am just interested in learning how to build amps. I'd like them to make me go "WOW" of course. I think tweaking existing amps would be helpful in learning as well. That's how I got interested in the first place.
Blessings, Terry
I have never heard an Aleph either. I just keep hearing good things about them.
The reason I have talked about watts and power is because most of the systems that have really sounded pleasing to me, always had a lot of headroom. It seems like the lower powered stuff lost something in the separation. I haven't heard a lot of stereophile type systems though.
I'm not sure what I would be using the MC modded Hafler for right now. If the audio quality is quite improved, I would probably use it in my studio to drive my nearfield monitors. Right now my Haflers are just sitting because my Soundcraftsmen amps just sound better. I've assumed that is because of the added headroom, but I could be wrong about that.
The main speakers I drive right now are some JBL 4425's and 4412's. My nearfields are Event 20/20's.
Right now I am just interested in learning how to build amps. I'd like them to make me go "WOW" of course. I think tweaking existing amps would be helpful in learning as well. That's how I got interested in the first place.
Blessings, Terry
Which Aleph?
Which Aleph are you considering? There are several of them in that series and then there is the X series of amps by Nelson Pass. The cheapest one to build I believe is the Aleph 3 or 30, don't know which. The Aleph 3 puts out 30 watts per channel. This would not provide much "headroom" as you define headroom, plus many who use this amp find a subwoofer crossed at around 150 is required. The little Aleph amps don't do bass very well.
I know nothing of the speakers you mention. How efficient are they? Speakers vary all over the place in efficiency. A speaker with an efficiency of 89db will play twice as loud as a speaker with 83db efficiency, with the same watts inputted. So "headroom" has a lot to do with the type of load the speaker presents to the amplifier.
I think the difference in sound is more to do with the topology of the card that holds the low level circuit. Your SC and Hafler amps all use MOSFETs as outputs but the Haflers do run on 65VDC rails whereas the SC runs on 70-75VDC rails, as I recall. The Haflers are 100-130 watts per channel whereas the SC is 200 watts per channel, as I recall. What are the differences in the typologies of the Hafler cards compared to those in the SC amp?
Have you read up on the "sound" of the different orders of harmonics? Single ended tube amplifiers and singled ended solid state circuits tend to have much more of the 2nd order harmonics in the output signal than do amps with a symmetrical circuit. Symmetrical circuits can get rid of almost all types of harmonics and distortion but they often times sound "dry" or "sterile" or overly "etched." Nelson Pass is quite candid about the fact that his single ended Aleph series have a lot of 2nd order harmonics in their output signal. Second order harmonics are usually interpreted by our ears/brains as "euphonic" and most people prefer the sound of an amp that has at least a certain percentage of 2nd order harmonics in its output.
The MC PA-3B circuit card is single-ended therefore it will sound different from the Hafler dual symmetrical circuit card. I prefer the sound of a single-ended circuit. The DH-120 amp has a single-ended circuit card as do the Hafler 9130 and 9180 amps, and they all sound very similar to each other and to the MC modded amp.
So, there is more to the sound of an amp than just "headroom."
Which Aleph are you considering? There are several of them in that series and then there is the X series of amps by Nelson Pass. The cheapest one to build I believe is the Aleph 3 or 30, don't know which. The Aleph 3 puts out 30 watts per channel. This would not provide much "headroom" as you define headroom, plus many who use this amp find a subwoofer crossed at around 150 is required. The little Aleph amps don't do bass very well.
I know nothing of the speakers you mention. How efficient are they? Speakers vary all over the place in efficiency. A speaker with an efficiency of 89db will play twice as loud as a speaker with 83db efficiency, with the same watts inputted. So "headroom" has a lot to do with the type of load the speaker presents to the amplifier.
I think the difference in sound is more to do with the topology of the card that holds the low level circuit. Your SC and Hafler amps all use MOSFETs as outputs but the Haflers do run on 65VDC rails whereas the SC runs on 70-75VDC rails, as I recall. The Haflers are 100-130 watts per channel whereas the SC is 200 watts per channel, as I recall. What are the differences in the typologies of the Hafler cards compared to those in the SC amp?
Have you read up on the "sound" of the different orders of harmonics? Single ended tube amplifiers and singled ended solid state circuits tend to have much more of the 2nd order harmonics in the output signal than do amps with a symmetrical circuit. Symmetrical circuits can get rid of almost all types of harmonics and distortion but they often times sound "dry" or "sterile" or overly "etched." Nelson Pass is quite candid about the fact that his single ended Aleph series have a lot of 2nd order harmonics in their output signal. Second order harmonics are usually interpreted by our ears/brains as "euphonic" and most people prefer the sound of an amp that has at least a certain percentage of 2nd order harmonics in its output.
The MC PA-3B circuit card is single-ended therefore it will sound different from the Hafler dual symmetrical circuit card. I prefer the sound of a single-ended circuit. The DH-120 amp has a single-ended circuit card as do the Hafler 9130 and 9180 amps, and they all sound very similar to each other and to the MC modded amp.
So, there is more to the sound of an amp than just "headroom."
Hi Dick,
Thanks for the detailed explanition.
The Aleph that was recommended to me was the Aleph X
Here are the specs for my cabinets;
JBL 4425
Frequency Response: 40Hz – 16 kHz +/- 3dB
Sensitivity (1W @ 1m): 91dB-SPL
Efficiency (Half-space 0.8% reference)
Nominal Impedance: 8ohm
Maximum Power Input: 200W
Short Term Peak(,10ms): 1 kw
http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1985-4425.htm
JBL 4412
Frequency Response ( -6dB): 35Hz – 27 kHz
Frequency Response ( +/- 2dB): 45Hz – 20 kHz
Sensitivity : 90dB-SPL., 1 watt (2.83 V) at 1 meter
Nominal Impedance: 8ohm
Power Rating: 150 watts, pink noise
http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1986-4400.htm
Event 20/20 passive
Frequency Response: 50Hz – 20kHz, +/-2dB, Ref 500Hz
Power Handling: 150W Program, 200W peak
Nominal Impedance: 4ohm
Sensitivity: 88dB @ 1W, im
http://www.event1.com/Support/Manuals/20_20.pdf
I will definately look into the single ended amps.
Thanks for taking the time to answer my questions.
Hey Bogie,
I don't think I'll be getting any Maggies any time soon. 😀
Blessings, Terry
Thanks for the detailed explanition.
The Aleph that was recommended to me was the Aleph X
Here are the specs for my cabinets;
JBL 4425
Frequency Response: 40Hz – 16 kHz +/- 3dB
Sensitivity (1W @ 1m): 91dB-SPL
Efficiency (Half-space 0.8% reference)
Nominal Impedance: 8ohm
Maximum Power Input: 200W
Short Term Peak(,10ms): 1 kw
http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1985-4425.htm
JBL 4412
Frequency Response ( -6dB): 35Hz – 27 kHz
Frequency Response ( +/- 2dB): 45Hz – 20 kHz
Sensitivity : 90dB-SPL., 1 watt (2.83 V) at 1 meter
Nominal Impedance: 8ohm
Power Rating: 150 watts, pink noise
http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1986-4400.htm
Event 20/20 passive
Frequency Response: 50Hz – 20kHz, +/-2dB, Ref 500Hz
Power Handling: 150W Program, 200W peak
Nominal Impedance: 4ohm
Sensitivity: 88dB @ 1W, im
http://www.event1.com/Support/Manuals/20_20.pdf
I will definately look into the single ended amps.
Thanks for taking the time to answer my questions.
Hey Bogie,
I don't think I'll be getting any Maggies any time soon. 😀
Blessings, Terry
Well, I tried to get Nelson Pass interested again here:
http://www.diyaudio.com/forums/showthread.php?postid=528479#post528479
Read a few posts further to see that he requested that someone send him an old Hafler. I took him up on the offer as I mentioned in the latest post on that thread. I have no idea what he will do with it, but I have sent him my amp. If the results are exciting, we can organize an upgrade kit or something!
I hope he doesn't convert it into a doorstop or something...
http://www.diyaudio.com/forums/showthread.php?postid=528479#post528479
Read a few posts further to see that he requested that someone send him an old Hafler. I took him up on the offer as I mentioned in the latest post on that thread. I have no idea what he will do with it, but I have sent him my amp. If the results are exciting, we can organize an upgrade kit or something!
I hope he doesn't convert it into a doorstop or something...
Yeah, well, these things aren't happy unless your amp can double as a welder...
I've got a buddy with a monster stack of Pflame Linears, and he keeps threatening to bring one over for a test...
I've got a buddy with a monster stack of Pflame Linears, and he keeps threatening to bring one over for a test...
Variac:
A doorstop? Perhaps a benchmark, after the
Pass Treatment. My amplifier(s) is a Leach, but
I'm curious to see old iron forged anew. Always
things to be learned studying as many designs as
I can.
I wish I had the money to build several different
projects, so I could compare them directly against
each other. Would there be a clear winner?
A doorstop? Perhaps a benchmark, after the
Pass Treatment. My amplifier(s) is a Leach, but
I'm curious to see old iron forged anew. Always
things to be learned studying as many designs as
I can.
I wish I had the money to build several different
projects, so I could compare them directly against
each other. Would there be a clear winner?
Let me make it clear that all I meant was that I have no control over what he makes out of it. I am assuming that he will continue to keep it as a power amp!,😉 If so, I am sure it will be WELL worth my while. But if he decided to turn it into an expresso machine I couldn't complain!
The charm of this arrangement is that I sent it to him without any idea what he has in mind.
A deal with the
?
or
?
We shall see.... but I'm 😀
2 posts after my post he explains his previous idea, which fits the Pass philosophy perfectly. BUT the issue is that the transformer has way too high voltage and the case waaay too little heat sinking to convert it into a Typical class A amp
The charm of this arrangement is that I sent it to him without any idea what he has in mind.
A deal with the
?or
?We shall see.... but I'm 😀
2 posts after my post he explains his previous idea, which fits the Pass philosophy perfectly. BUT the issue is that the transformer has way too high voltage and the case waaay too little heat sinking to convert it into a Typical class A amp
There are so many old Hafler DH-200 amps floating around that it is a shame someone can't find an upgrade circuit board that is cheaper than the MC cards.
All the Haflers I have examined had the domestic transformer, however. To do a small class A amp one would need a different transformer. But, the old chassis and MOSFETs are cheap enough off eBay to make any project using them worthwhile.
Luckily, I just happen to have a pair of old Dynaco ST-150 transformers from the very early '80s. These transformers are just a tad larger than the Hafler transformer but same form factor and can be made to fit in a Hafler chassis. These transformers provided 50 VDC and 70 VDC +/- but they have dual sets of primary windings. Therefore, hooking up this transformer as if for 220VAC will provide either 25VDC or 35VDC, nice voltages for a small class A amp.
So, I am very interested. I hope Mr. Pass comes up with a good solution. And, I will probably sell the extra ST-150 transformer to someone who is interested. Should I post it on the "for sale" thread? It is Dynaco part number 464 090 and I am told it is the same transformer used in the ST-300 amp.
Whatta' hobby!
All the Haflers I have examined had the domestic transformer, however. To do a small class A amp one would need a different transformer. But, the old chassis and MOSFETs are cheap enough off eBay to make any project using them worthwhile.
Luckily, I just happen to have a pair of old Dynaco ST-150 transformers from the very early '80s. These transformers are just a tad larger than the Hafler transformer but same form factor and can be made to fit in a Hafler chassis. These transformers provided 50 VDC and 70 VDC +/- but they have dual sets of primary windings. Therefore, hooking up this transformer as if for 220VAC will provide either 25VDC or 35VDC, nice voltages for a small class A amp.
So, I am very interested. I hope Mr. Pass comes up with a good solution. And, I will probably sell the extra ST-150 transformer to someone who is interested. Should I post it on the "for sale" thread? It is Dynaco part number 464 090 and I am told it is the same transformer used in the ST-300 amp.
Whatta' hobby!
- Status
- Not open for further replies.